multi_buffer.rs

   1mod anchor;
   2#[cfg(test)]
   3mod multi_buffer_tests;
   4mod path_key;
   5mod transaction;
   6
   7use self::transaction::History;
   8
   9pub use anchor::{Anchor, AnchorRangeExt};
  10
  11use anyhow::{Result, anyhow};
  12use buffer_diff::{
  13    BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffChanged, DiffHunkSecondaryStatus,
  14    DiffHunkStatus, DiffHunkStatusKind,
  15};
  16use clock::ReplicaId;
  17use collections::{BTreeMap, Bound, HashMap, HashSet};
  18use gpui::{App, Context, Entity, EntityId, EventEmitter};
  19use itertools::Itertools;
  20use language::{
  21    AutoindentMode, BracketMatch, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability,
  22    CharClassifier, CharKind, CharScopeContext, Chunk, CursorShape, DiagnosticEntryRef, File,
  23    IndentGuideSettings, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16, Outline,
  24    OutlineItem, Point, PointUtf16, Selection, TextDimension, TextObject, ToOffset as _,
  25    ToPoint as _, TransactionId, TreeSitterOptions, Unclipped,
  26    language_settings::{LanguageSettings, language_settings},
  27};
  28
  29#[cfg(any(test, feature = "test-support"))]
  30use gpui::AppContext as _;
  31
  32use rope::DimensionPair;
  33use smallvec::SmallVec;
  34use smol::future::yield_now;
  35use std::{
  36    any::type_name,
  37    borrow::Cow,
  38    cell::{Cell, OnceCell, Ref, RefCell},
  39    cmp, fmt,
  40    future::Future,
  41    io,
  42    iter::{self, FromIterator},
  43    mem,
  44    ops::{self, Add, AddAssign, ControlFlow, Range, RangeBounds, Sub, SubAssign},
  45    rc::Rc,
  46    str,
  47    sync::{Arc, OnceLock},
  48    time::Duration,
  49};
  50use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, TreeMap};
  51use text::{
  52    BufferId, Edit, LineIndent, TextSummary,
  53    locator::Locator,
  54    subscription::{Subscription, Topic},
  55};
  56use theme::SyntaxTheme;
  57use util::post_inc;
  58use ztracing::instrument;
  59
  60pub use self::path_key::{PathExcerptInsertResult, PathKey};
  61
  62pub static EXCERPT_CONTEXT_LINES: OnceLock<fn(&App) -> u32> = OnceLock::new();
  63
  64pub fn excerpt_context_lines(cx: &App) -> u32 {
  65    EXCERPT_CONTEXT_LINES.get().map(|f| f(cx)).unwrap_or(2)
  66}
  67
  68#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  69pub struct ExcerptId(u32);
  70
  71/// One or more [`Buffers`](Buffer) being edited in a single view.
  72///
  73/// See <https://zed.dev/features#multi-buffers>
  74pub struct MultiBuffer {
  75    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  76    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  77    snapshot: RefCell<MultiBufferSnapshot>,
  78    /// Contains the state of the buffers being edited
  79    buffers: BTreeMap<BufferId, BufferState>,
  80    /// Mapping from path keys to their excerpts.
  81    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  82    /// Mapping from excerpt IDs to their path key.
  83    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  84    /// Mapping from buffer IDs to their diff states
  85    diffs: HashMap<BufferId, DiffState>,
  86    subscriptions: Topic<MultiBufferOffset>,
  87    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  88    singleton: bool,
  89    /// The history of the multi-buffer.
  90    history: History,
  91    /// The explicit title of the multi-buffer.
  92    /// If `None`, it will be derived from the underlying path or content.
  93    title: Option<String>,
  94    /// The writing capability of the multi-buffer.
  95    capability: Capability,
  96    buffer_changed_since_sync: Rc<Cell<bool>>,
  97}
  98
  99#[derive(Clone, Debug, PartialEq, Eq)]
 100pub enum Event {
 101    ExcerptsAdded {
 102        buffer: Entity<Buffer>,
 103        predecessor: ExcerptId,
 104        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
 105    },
 106    ExcerptsRemoved {
 107        ids: Vec<ExcerptId>,
 108        /// Contains only buffer IDs for which all excerpts have been removed.
 109        /// Buffers that still have remaining excerpts are never included.
 110        removed_buffer_ids: Vec<BufferId>,
 111    },
 112    ExcerptsExpanded {
 113        ids: Vec<ExcerptId>,
 114    },
 115    ExcerptsEdited {
 116        excerpt_ids: Vec<ExcerptId>,
 117        buffer_ids: Vec<BufferId>,
 118    },
 119    DiffHunksToggled,
 120    Edited {
 121        edited_buffer: Option<Entity<Buffer>>,
 122        is_local: bool,
 123    },
 124    TransactionUndone {
 125        transaction_id: TransactionId,
 126    },
 127    Reloaded,
 128    LanguageChanged(BufferId, bool),
 129    Reparsed(BufferId),
 130    Saved,
 131    FileHandleChanged,
 132    DirtyChanged,
 133    DiagnosticsUpdated,
 134    BufferDiffChanged,
 135}
 136
 137/// A diff hunk, representing a range of consequent lines in a multibuffer.
 138#[derive(Debug, Clone, PartialEq, Eq)]
 139pub struct MultiBufferDiffHunk {
 140    /// The row range in the multibuffer where this diff hunk appears.
 141    pub row_range: Range<MultiBufferRow>,
 142    /// The buffer ID that this hunk belongs to.
 143    pub buffer_id: BufferId,
 144    /// The range of the underlying buffer that this hunk corresponds to.
 145    pub buffer_range: Range<text::Anchor>,
 146    /// The excerpt that contains the diff hunk.
 147    pub excerpt_id: ExcerptId,
 148    /// The range within the buffer's diff base that this hunk corresponds to.
 149    pub diff_base_byte_range: Range<BufferOffset>,
 150    /// The status of this hunk (added/modified/deleted and secondary status).
 151    pub status: DiffHunkStatus,
 152    /// The word diffs for this hunk.
 153    pub word_diffs: Vec<Range<MultiBufferOffset>>,
 154}
 155
 156impl MultiBufferDiffHunk {
 157    pub fn status(&self) -> DiffHunkStatus {
 158        self.status
 159    }
 160
 161    pub fn is_created_file(&self) -> bool {
 162        self.diff_base_byte_range == (BufferOffset(0)..BufferOffset(0))
 163            && self.buffer_range.start.is_min()
 164            && self.buffer_range.end.is_max()
 165    }
 166
 167    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 168        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_range.start);
 169        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_range.end);
 170        start..end
 171    }
 172}
 173
 174pub type MultiBufferPoint = Point;
 175type ExcerptOffset = ExcerptDimension<MultiBufferOffset>;
 176type ExcerptPoint = ExcerptDimension<Point>;
 177
 178#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 179#[serde(transparent)]
 180pub struct MultiBufferRow(pub u32);
 181
 182impl MultiBufferRow {
 183    pub const MIN: Self = Self(0);
 184    pub const MAX: Self = Self(u32::MAX);
 185}
 186
 187impl ops::Add<usize> for MultiBufferRow {
 188    type Output = Self;
 189
 190    fn add(self, rhs: usize) -> Self::Output {
 191        MultiBufferRow(self.0 + rhs as u32)
 192    }
 193}
 194
 195pub trait MultiBufferDimension: 'static + Copy + Default + std::fmt::Debug {
 196    type TextDimension: TextDimension;
 197    fn from_summary(summary: &MBTextSummary) -> Self;
 198
 199    fn add_text_dim(&mut self, summary: &Self::TextDimension);
 200
 201    fn add_mb_text_summary(&mut self, summary: &MBTextSummary);
 202}
 203
 204// todo(lw): MultiBufferPoint
 205impl MultiBufferDimension for Point {
 206    type TextDimension = Point;
 207    fn from_summary(summary: &MBTextSummary) -> Self {
 208        summary.lines
 209    }
 210
 211    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 212        *self += *other;
 213    }
 214
 215    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 216        *self += summary.lines;
 217    }
 218}
 219
 220// todo(lw): MultiBufferPointUtf16
 221impl MultiBufferDimension for PointUtf16 {
 222    type TextDimension = PointUtf16;
 223    fn from_summary(summary: &MBTextSummary) -> Self {
 224        summary.lines_utf16()
 225    }
 226
 227    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 228        *self += *other;
 229    }
 230
 231    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 232        *self += summary.lines_utf16();
 233    }
 234}
 235
 236#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 237pub struct MultiBufferOffset(pub usize);
 238
 239impl fmt::Display for MultiBufferOffset {
 240    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 241        write!(f, "{}", self.0)
 242    }
 243}
 244
 245impl rand::distr::uniform::SampleUniform for MultiBufferOffset {
 246    type Sampler = MultiBufferOffsetUniformSampler;
 247}
 248
 249pub struct MultiBufferOffsetUniformSampler {
 250    sampler: rand::distr::uniform::UniformUsize,
 251}
 252
 253impl rand::distr::uniform::UniformSampler for MultiBufferOffsetUniformSampler {
 254    type X = MultiBufferOffset;
 255
 256    fn new<B1, B2>(low_b: B1, high_b: B2) -> Result<Self, rand::distr::uniform::Error>
 257    where
 258        B1: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 259        B2: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 260    {
 261        let low = *low_b.borrow();
 262        let high = *high_b.borrow();
 263        let sampler = rand::distr::uniform::UniformUsize::new(low.0, high.0);
 264        sampler.map(|sampler| MultiBufferOffsetUniformSampler { sampler })
 265    }
 266
 267    #[inline] // if the range is constant, this helps LLVM to do the
 268    // calculations at compile-time.
 269    fn new_inclusive<B1, B2>(low_b: B1, high_b: B2) -> Result<Self, rand::distr::uniform::Error>
 270    where
 271        B1: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 272        B2: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 273    {
 274        let low = *low_b.borrow();
 275        let high = *high_b.borrow();
 276        let sampler = rand::distr::uniform::UniformUsize::new_inclusive(low.0, high.0);
 277        sampler.map(|sampler| MultiBufferOffsetUniformSampler { sampler })
 278    }
 279
 280    fn sample<R: rand::Rng + ?Sized>(&self, rng: &mut R) -> Self::X {
 281        MultiBufferOffset(self.sampler.sample(rng))
 282    }
 283}
 284impl MultiBufferDimension for MultiBufferOffset {
 285    type TextDimension = usize;
 286    fn from_summary(summary: &MBTextSummary) -> Self {
 287        summary.len
 288    }
 289
 290    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 291        self.0 += *other;
 292    }
 293
 294    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 295        *self += summary.len;
 296    }
 297}
 298impl MultiBufferDimension for MultiBufferOffsetUtf16 {
 299    type TextDimension = OffsetUtf16;
 300    fn from_summary(summary: &MBTextSummary) -> Self {
 301        MultiBufferOffsetUtf16(summary.len_utf16)
 302    }
 303
 304    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 305        self.0 += *other;
 306    }
 307
 308    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 309        self.0 += summary.len_utf16;
 310    }
 311}
 312
 313#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 314pub struct BufferOffset(pub usize);
 315
 316impl TextDimension for BufferOffset {
 317    fn from_text_summary(summary: &TextSummary) -> Self {
 318        BufferOffset(usize::from_text_summary(summary))
 319    }
 320    fn from_chunk(chunk: rope::ChunkSlice) -> Self {
 321        BufferOffset(usize::from_chunk(chunk))
 322    }
 323    fn add_assign(&mut self, other: &Self) {
 324        TextDimension::add_assign(&mut self.0, &other.0);
 325    }
 326}
 327impl<'a> sum_tree::Dimension<'a, rope::ChunkSummary> for BufferOffset {
 328    fn zero(cx: ()) -> Self {
 329        BufferOffset(<usize as sum_tree::Dimension<'a, rope::ChunkSummary>>::zero(cx))
 330    }
 331
 332    fn add_summary(&mut self, summary: &'a rope::ChunkSummary, cx: ()) {
 333        usize::add_summary(&mut self.0, summary, cx);
 334    }
 335}
 336
 337impl Sub for BufferOffset {
 338    type Output = usize;
 339
 340    fn sub(self, other: BufferOffset) -> Self::Output {
 341        self.0 - other.0
 342    }
 343}
 344
 345impl AddAssign<DimensionPair<usize, Point>> for BufferOffset {
 346    fn add_assign(&mut self, other: DimensionPair<usize, Point>) {
 347        self.0 += other.key;
 348    }
 349}
 350
 351impl language::ToPoint for BufferOffset {
 352    fn to_point(&self, snapshot: &text::BufferSnapshot) -> Point {
 353        self.0.to_point(snapshot)
 354    }
 355}
 356
 357impl language::ToPointUtf16 for BufferOffset {
 358    fn to_point_utf16(&self, snapshot: &text::BufferSnapshot) -> PointUtf16 {
 359        self.0.to_point_utf16(snapshot)
 360    }
 361}
 362
 363impl language::ToOffset for BufferOffset {
 364    fn to_offset(&self, snapshot: &text::BufferSnapshot) -> usize {
 365        self.0.to_offset(snapshot)
 366    }
 367}
 368
 369impl language::ToOffsetUtf16 for BufferOffset {
 370    fn to_offset_utf16(&self, snapshot: &text::BufferSnapshot) -> OffsetUtf16 {
 371        self.0.to_offset_utf16(snapshot)
 372    }
 373}
 374
 375#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
 376pub struct MultiBufferOffsetUtf16(pub OffsetUtf16);
 377
 378impl ops::Add<usize> for MultiBufferOffsetUtf16 {
 379    type Output = MultiBufferOffsetUtf16;
 380
 381    fn add(self, rhs: usize) -> Self::Output {
 382        MultiBufferOffsetUtf16(OffsetUtf16(self.0.0 + rhs))
 383    }
 384}
 385
 386impl ops::Add<OffsetUtf16> for MultiBufferOffsetUtf16 {
 387    type Output = Self;
 388
 389    fn add(self, rhs: OffsetUtf16) -> Self::Output {
 390        MultiBufferOffsetUtf16(self.0 + rhs)
 391    }
 392}
 393
 394impl AddAssign<OffsetUtf16> for MultiBufferOffsetUtf16 {
 395    fn add_assign(&mut self, rhs: OffsetUtf16) {
 396        self.0 += rhs;
 397    }
 398}
 399
 400impl AddAssign<usize> for MultiBufferOffsetUtf16 {
 401    fn add_assign(&mut self, rhs: usize) {
 402        self.0.0 += rhs;
 403    }
 404}
 405
 406impl Sub for MultiBufferOffsetUtf16 {
 407    type Output = OffsetUtf16;
 408
 409    fn sub(self, other: MultiBufferOffsetUtf16) -> Self::Output {
 410        self.0 - other.0
 411    }
 412}
 413
 414impl Sub<OffsetUtf16> for MultiBufferOffsetUtf16 {
 415    type Output = MultiBufferOffsetUtf16;
 416
 417    fn sub(self, other: OffsetUtf16) -> Self::Output {
 418        MultiBufferOffsetUtf16(self.0 - other)
 419    }
 420}
 421
 422#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
 423pub struct BufferOffsetUtf16(pub OffsetUtf16);
 424
 425impl MultiBufferOffset {
 426    const ZERO: Self = Self(0);
 427    pub fn saturating_sub(self, other: MultiBufferOffset) -> usize {
 428        self.0.saturating_sub(other.0)
 429    }
 430    pub fn saturating_sub_usize(self, other: usize) -> MultiBufferOffset {
 431        MultiBufferOffset(self.0.saturating_sub(other))
 432    }
 433}
 434
 435impl ops::Sub for MultiBufferOffset {
 436    type Output = usize;
 437
 438    fn sub(self, other: MultiBufferOffset) -> Self::Output {
 439        self.0 - other.0
 440    }
 441}
 442
 443impl ops::Sub<usize> for MultiBufferOffset {
 444    type Output = Self;
 445
 446    fn sub(self, other: usize) -> Self::Output {
 447        MultiBufferOffset(self.0 - other)
 448    }
 449}
 450
 451impl ops::SubAssign<usize> for MultiBufferOffset {
 452    fn sub_assign(&mut self, other: usize) {
 453        self.0 -= other;
 454    }
 455}
 456
 457impl ops::Add<usize> for BufferOffset {
 458    type Output = Self;
 459
 460    fn add(self, rhs: usize) -> Self::Output {
 461        BufferOffset(self.0 + rhs)
 462    }
 463}
 464
 465impl ops::AddAssign<usize> for BufferOffset {
 466    fn add_assign(&mut self, other: usize) {
 467        self.0 += other;
 468    }
 469}
 470
 471impl ops::Add<usize> for MultiBufferOffset {
 472    type Output = Self;
 473
 474    fn add(self, rhs: usize) -> Self::Output {
 475        MultiBufferOffset(self.0 + rhs)
 476    }
 477}
 478
 479impl ops::AddAssign<usize> for MultiBufferOffset {
 480    fn add_assign(&mut self, other: usize) {
 481        self.0 += other;
 482    }
 483}
 484
 485impl ops::Add<isize> for MultiBufferOffset {
 486    type Output = Self;
 487
 488    fn add(self, rhs: isize) -> Self::Output {
 489        MultiBufferOffset((self.0 as isize + rhs) as usize)
 490    }
 491}
 492
 493impl ops::Add for MultiBufferOffset {
 494    type Output = Self;
 495
 496    fn add(self, rhs: MultiBufferOffset) -> Self::Output {
 497        MultiBufferOffset(self.0 + rhs.0)
 498    }
 499}
 500
 501impl ops::AddAssign<MultiBufferOffset> for MultiBufferOffset {
 502    fn add_assign(&mut self, other: MultiBufferOffset) {
 503        self.0 += other.0;
 504    }
 505}
 506
 507pub trait ToOffset: 'static + fmt::Debug {
 508    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset;
 509    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16;
 510}
 511
 512pub trait ToPoint: 'static + fmt::Debug {
 513    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 514    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 515}
 516
 517struct BufferState {
 518    buffer: Entity<Buffer>,
 519    last_version: RefCell<clock::Global>,
 520    last_non_text_state_update_count: Cell<usize>,
 521    // Note, any changes to this field value require updating snapshot.buffer_locators as well
 522    excerpts: Vec<Locator>,
 523    _subscriptions: [gpui::Subscription; 2],
 524}
 525
 526struct DiffState {
 527    diff: Entity<BufferDiff>,
 528    main_buffer: Option<Entity<language::Buffer>>,
 529    _subscription: gpui::Subscription,
 530}
 531
 532impl DiffState {
 533    fn snapshot(&self, cx: &App) -> DiffStateSnapshot {
 534        DiffStateSnapshot {
 535            diff: self.diff.read(cx).snapshot(cx),
 536            main_buffer: self.main_buffer.as_ref().map(|b| b.read(cx).snapshot()),
 537        }
 538    }
 539}
 540
 541#[derive(Clone)]
 542struct DiffStateSnapshot {
 543    diff: BufferDiffSnapshot,
 544    main_buffer: Option<language::BufferSnapshot>,
 545}
 546
 547impl std::ops::Deref for DiffStateSnapshot {
 548    type Target = BufferDiffSnapshot;
 549
 550    fn deref(&self) -> &Self::Target {
 551        &self.diff
 552    }
 553}
 554
 555impl DiffState {
 556    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 557        DiffState {
 558            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 559                BufferDiffEvent::DiffChanged(DiffChanged {
 560                    changed_range,
 561                    base_text_changed_range: _,
 562                    extended_range,
 563                }) => {
 564                    let use_extended = this.snapshot.borrow().use_extended_diff_range;
 565                    let range = if use_extended {
 566                        extended_range.clone()
 567                    } else {
 568                        changed_range.clone()
 569                    };
 570                    if let Some(range) = range {
 571                        this.buffer_diff_changed(diff, range, cx)
 572                    }
 573                    cx.emit(Event::BufferDiffChanged);
 574                }
 575                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 576                _ => {}
 577            }),
 578            diff,
 579            main_buffer: None,
 580        }
 581    }
 582
 583    fn new_inverted(
 584        diff: Entity<BufferDiff>,
 585        main_buffer: Entity<language::Buffer>,
 586        cx: &mut Context<MultiBuffer>,
 587    ) -> Self {
 588        let weak_main_buffer = main_buffer.downgrade();
 589        DiffState {
 590            _subscription: cx.subscribe(&diff, {
 591                move |this, diff, event, cx| {
 592                    let Some(main_buffer) = weak_main_buffer.upgrade() else {
 593                        return;
 594                    };
 595                    match event {
 596                        BufferDiffEvent::DiffChanged(DiffChanged {
 597                            changed_range: _,
 598                            base_text_changed_range,
 599                            extended_range: _,
 600                        }) => {
 601                            this.inverted_buffer_diff_changed(
 602                                diff,
 603                                main_buffer,
 604                                base_text_changed_range.clone(),
 605                                cx,
 606                            );
 607                            cx.emit(Event::BufferDiffChanged);
 608                        }
 609                        BufferDiffEvent::LanguageChanged => {
 610                            this.inverted_buffer_diff_language_changed(diff, main_buffer, cx)
 611                        }
 612                        _ => {}
 613                    }
 614                }
 615            }),
 616            diff,
 617            main_buffer: Some(main_buffer),
 618        }
 619    }
 620}
 621
 622/// The contents of a [`MultiBuffer`] at a single point in time.
 623#[derive(Clone, Default)]
 624pub struct MultiBufferSnapshot {
 625    excerpts: SumTree<Excerpt>,
 626    buffer_locators: TreeMap<BufferId, Arc<[Locator]>>,
 627    diffs: TreeMap<BufferId, DiffStateSnapshot>,
 628    diff_transforms: SumTree<DiffTransform>,
 629    excerpt_ids: SumTree<ExcerptIdMapping>,
 630    replaced_excerpts: Arc<HashMap<ExcerptId, ExcerptId>>,
 631    non_text_state_update_count: usize,
 632    edit_count: usize,
 633    is_dirty: bool,
 634    has_deleted_file: bool,
 635    has_conflict: bool,
 636    has_inverted_diff: bool,
 637    singleton: bool,
 638    trailing_excerpt_update_count: usize,
 639    all_diff_hunks_expanded: bool,
 640    show_deleted_hunks: bool,
 641    use_extended_diff_range: bool,
 642    show_headers: bool,
 643}
 644
 645// follower: None
 646// - BufferContent(Some)
 647// - BufferContent(None)
 648// - DeletedHunk
 649//
 650// follower: Some
 651// - BufferContent(Some)
 652// - BufferContent(None)
 653
 654#[derive(Debug, Clone)]
 655enum DiffTransform {
 656    // RealText
 657    BufferContent {
 658        summary: MBTextSummary,
 659        // modified_hunk_info
 660        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 661    },
 662    // ExpandedHunkText
 663    DeletedHunk {
 664        summary: TextSummary,
 665        buffer_id: BufferId,
 666        hunk_info: DiffTransformHunkInfo,
 667        base_text_byte_range: Range<usize>,
 668        has_trailing_newline: bool,
 669    },
 670}
 671
 672#[derive(Clone, Copy, Debug)]
 673struct DiffTransformHunkInfo {
 674    excerpt_id: ExcerptId,
 675    hunk_start_anchor: text::Anchor,
 676    hunk_secondary_status: DiffHunkSecondaryStatus,
 677    is_logically_deleted: bool,
 678}
 679
 680impl Eq for DiffTransformHunkInfo {}
 681
 682impl PartialEq for DiffTransformHunkInfo {
 683    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 684        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 685    }
 686}
 687
 688impl std::hash::Hash for DiffTransformHunkInfo {
 689    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 690        self.excerpt_id.hash(state);
 691        self.hunk_start_anchor.hash(state);
 692    }
 693}
 694
 695#[derive(Clone)]
 696pub struct ExcerptInfo {
 697    pub id: ExcerptId,
 698    pub buffer: Arc<BufferSnapshot>,
 699    pub buffer_id: BufferId,
 700    pub range: ExcerptRange<text::Anchor>,
 701    pub end_row: MultiBufferRow,
 702}
 703
 704impl std::fmt::Debug for ExcerptInfo {
 705    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 706        f.debug_struct(type_name::<Self>())
 707            .field("id", &self.id)
 708            .field("buffer_id", &self.buffer_id)
 709            .field("path", &self.buffer.file().map(|f| f.path()))
 710            .field("range", &self.range)
 711            .finish()
 712    }
 713}
 714
 715/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 716#[derive(Debug)]
 717pub struct ExcerptBoundary {
 718    pub prev: Option<ExcerptInfo>,
 719    pub next: ExcerptInfo,
 720    /// The row in the `MultiBuffer` where the boundary is located
 721    pub row: MultiBufferRow,
 722}
 723
 724impl ExcerptBoundary {
 725    pub fn starts_new_buffer(&self) -> bool {
 726        match (self.prev.as_ref(), &self.next) {
 727            (None, _) => true,
 728            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 729        }
 730    }
 731}
 732
 733#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 734pub struct ExpandInfo {
 735    pub direction: ExpandExcerptDirection,
 736    pub excerpt_id: ExcerptId,
 737}
 738
 739#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 740pub struct RowInfo {
 741    pub buffer_id: Option<BufferId>,
 742    pub buffer_row: Option<u32>,
 743    pub multibuffer_row: Option<MultiBufferRow>,
 744    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 745    pub expand_info: Option<ExpandInfo>,
 746    pub wrapped_buffer_row: Option<u32>,
 747}
 748
 749/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 750#[derive(Clone)]
 751struct Excerpt {
 752    /// The unique identifier for this excerpt
 753    id: ExcerptId,
 754    /// The location of the excerpt in the [`MultiBuffer`]
 755    locator: Locator,
 756    /// The buffer being excerpted
 757    buffer_id: BufferId,
 758    /// A snapshot of the buffer being excerpted
 759    buffer: Arc<BufferSnapshot>,
 760    /// The range of the buffer to be shown in the excerpt
 761    range: ExcerptRange<text::Anchor>,
 762    /// The last row in the excerpted slice of the buffer
 763    max_buffer_row: BufferRow,
 764    /// A summary of the text in the excerpt
 765    text_summary: TextSummary,
 766    has_trailing_newline: bool,
 767}
 768
 769/// A public view into an `Excerpt` in a [`MultiBuffer`].
 770///
 771/// Contains methods for getting the [`Buffer`] of the excerpt,
 772/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 773#[derive(Clone)]
 774pub struct MultiBufferExcerpt<'a> {
 775    excerpt: &'a Excerpt,
 776    diff_transforms:
 777        sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<MultiBufferOffset>>,
 778    /// The offset in the multibuffer considering diff transforms.
 779    offset: MultiBufferOffset,
 780    /// The offset in the multibuffer without diff transforms.
 781    excerpt_offset: ExcerptOffset,
 782    buffer_offset: BufferOffset,
 783}
 784
 785#[derive(Clone, Debug)]
 786struct ExcerptIdMapping {
 787    id: ExcerptId,
 788    locator: Locator,
 789}
 790
 791/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 792/// These ranges are relative to the buffer itself
 793#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 794pub struct ExcerptRange<T> {
 795    /// The full range of text to be shown in the excerpt.
 796    pub context: Range<T>,
 797    /// The primary range of text to be highlighted in the excerpt.
 798    /// In a multi-buffer search, this would be the text that matched the search
 799    pub primary: Range<T>,
 800}
 801
 802impl<T: Clone> ExcerptRange<T> {
 803    pub fn new(context: Range<T>) -> Self {
 804        Self {
 805            context: context.clone(),
 806            primary: context,
 807        }
 808    }
 809}
 810
 811#[derive(Clone, Debug, Default)]
 812pub struct ExcerptSummary {
 813    excerpt_id: ExcerptId,
 814    /// The location of the last [`Excerpt`] being summarized
 815    excerpt_locator: Locator,
 816    widest_line_number: u32,
 817    text: MBTextSummary,
 818    count: usize,
 819}
 820
 821#[derive(Debug, Clone)]
 822pub struct DiffTransformSummary {
 823    input: MBTextSummary,
 824    output: MBTextSummary,
 825}
 826
 827/// Summary of a string of text.
 828#[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
 829pub struct MBTextSummary {
 830    /// Length in bytes.
 831    pub len: MultiBufferOffset,
 832    /// Length in UTF-8.
 833    pub chars: usize,
 834    /// Length in UTF-16 code units
 835    pub len_utf16: OffsetUtf16,
 836    /// A point representing the number of lines and the length of the last line.
 837    ///
 838    /// In other words, it marks the point after the last byte in the text, (if
 839    /// EOF was a character, this would be its position).
 840    pub lines: Point,
 841    /// How many `char`s are in the first line
 842    pub first_line_chars: u32,
 843    /// How many `char`s are in the last line
 844    pub last_line_chars: u32,
 845    /// How many UTF-16 code units are in the last line
 846    pub last_line_len_utf16: u32,
 847    /// The row idx of the longest row
 848    pub longest_row: u32,
 849    /// How many `char`s are in the longest row
 850    pub longest_row_chars: u32,
 851}
 852
 853impl From<TextSummary> for MBTextSummary {
 854    fn from(summary: TextSummary) -> Self {
 855        MBTextSummary {
 856            len: MultiBufferOffset(summary.len),
 857            chars: summary.chars,
 858            len_utf16: summary.len_utf16,
 859            lines: summary.lines,
 860            first_line_chars: summary.first_line_chars,
 861            last_line_chars: summary.last_line_chars,
 862            last_line_len_utf16: summary.last_line_len_utf16,
 863            longest_row: summary.longest_row,
 864            longest_row_chars: summary.longest_row_chars,
 865        }
 866    }
 867}
 868
 869impl From<MBTextSummary> for TextSummary {
 870    fn from(summary: MBTextSummary) -> Self {
 871        TextSummary {
 872            len: summary.len.0,
 873            chars: summary.chars,
 874            len_utf16: summary.len_utf16,
 875            lines: summary.lines,
 876            first_line_chars: summary.first_line_chars,
 877            last_line_chars: summary.last_line_chars,
 878            last_line_len_utf16: summary.last_line_len_utf16,
 879            longest_row: summary.longest_row,
 880            longest_row_chars: summary.longest_row_chars,
 881        }
 882    }
 883}
 884
 885impl From<&str> for MBTextSummary {
 886    fn from(text: &str) -> Self {
 887        MBTextSummary::from(TextSummary::from(text))
 888    }
 889}
 890
 891impl MultiBufferDimension for MBTextSummary {
 892    type TextDimension = TextSummary;
 893
 894    fn from_summary(summary: &MBTextSummary) -> Self {
 895        *summary
 896    }
 897
 898    fn add_text_dim(&mut self, summary: &Self::TextDimension) {
 899        *self += *summary;
 900    }
 901
 902    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 903        *self += *summary;
 904    }
 905}
 906
 907impl AddAssign for MBTextSummary {
 908    fn add_assign(&mut self, other: MBTextSummary) {
 909        let joined_chars = self.last_line_chars + other.first_line_chars;
 910        if joined_chars > self.longest_row_chars {
 911            self.longest_row = self.lines.row;
 912            self.longest_row_chars = joined_chars;
 913        }
 914        if other.longest_row_chars > self.longest_row_chars {
 915            self.longest_row = self.lines.row + other.longest_row;
 916            self.longest_row_chars = other.longest_row_chars;
 917        }
 918
 919        if self.lines.row == 0 {
 920            self.first_line_chars += other.first_line_chars;
 921        }
 922
 923        if other.lines.row == 0 {
 924            self.last_line_chars += other.first_line_chars;
 925            self.last_line_len_utf16 += other.last_line_len_utf16;
 926        } else {
 927            self.last_line_chars = other.last_line_chars;
 928            self.last_line_len_utf16 = other.last_line_len_utf16;
 929        }
 930
 931        self.chars += other.chars;
 932        self.len += other.len;
 933        self.len_utf16 += other.len_utf16;
 934        self.lines += other.lines;
 935    }
 936}
 937
 938impl AddAssign<TextSummary> for MBTextSummary {
 939    fn add_assign(&mut self, other: TextSummary) {
 940        *self += MBTextSummary::from(other);
 941    }
 942}
 943
 944impl MBTextSummary {
 945    pub fn lines_utf16(&self) -> PointUtf16 {
 946        PointUtf16 {
 947            row: self.lines.row,
 948            column: self.last_line_len_utf16,
 949        }
 950    }
 951}
 952
 953impl<K, V> MultiBufferDimension for DimensionPair<K, V>
 954where
 955    K: MultiBufferDimension,
 956    V: MultiBufferDimension,
 957{
 958    type TextDimension = DimensionPair<K::TextDimension, V::TextDimension>;
 959
 960    fn from_summary(summary: &MBTextSummary) -> Self {
 961        Self {
 962            key: K::from_summary(summary),
 963            value: Some(V::from_summary(summary)),
 964        }
 965    }
 966
 967    fn add_text_dim(&mut self, summary: &Self::TextDimension) {
 968        self.key.add_text_dim(&summary.key);
 969        if let Some(value) = &mut self.value {
 970            if let Some(other_value) = summary.value.as_ref() {
 971                value.add_text_dim(other_value);
 972            }
 973        }
 974    }
 975
 976    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 977        self.key.add_mb_text_summary(summary);
 978        if let Some(value) = &mut self.value {
 979            value.add_mb_text_summary(summary);
 980        }
 981    }
 982}
 983
 984#[derive(Clone)]
 985pub struct MultiBufferRows<'a> {
 986    point: Point,
 987    is_empty: bool,
 988    is_singleton: bool,
 989    cursor: MultiBufferCursor<'a, Point, Point>,
 990}
 991
 992pub struct MultiBufferChunks<'a> {
 993    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 994    diff_transforms:
 995        Cursor<'a, 'static, DiffTransform, Dimensions<MultiBufferOffset, ExcerptOffset>>,
 996    diffs: &'a TreeMap<BufferId, DiffStateSnapshot>,
 997    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 998    buffer_chunk: Option<Chunk<'a>>,
 999    range: Range<MultiBufferOffset>,
1000    excerpt_offset_range: Range<ExcerptOffset>,
1001    excerpt_chunks: Option<ExcerptChunks<'a>>,
1002    language_aware: bool,
1003}
1004
1005pub struct ReversedMultiBufferChunks<'a> {
1006    cursor: MultiBufferCursor<'a, MultiBufferOffset, BufferOffset>,
1007    current_chunks: Option<rope::Chunks<'a>>,
1008    start: MultiBufferOffset,
1009    offset: MultiBufferOffset,
1010}
1011
1012pub struct MultiBufferBytes<'a> {
1013    range: Range<MultiBufferOffset>,
1014    cursor: MultiBufferCursor<'a, MultiBufferOffset, BufferOffset>,
1015    excerpt_bytes: Option<text::Bytes<'a>>,
1016    has_trailing_newline: bool,
1017    chunk: &'a [u8],
1018}
1019
1020pub struct ReversedMultiBufferBytes<'a> {
1021    range: Range<MultiBufferOffset>,
1022    chunks: ReversedMultiBufferChunks<'a>,
1023    chunk: &'a [u8],
1024}
1025
1026#[derive(Clone)]
1027struct DiffTransforms<MBD> {
1028    output_dimension: OutputDimension<MBD>,
1029    excerpt_dimension: ExcerptDimension<MBD>,
1030}
1031
1032impl<'a, MBD: MultiBufferDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<MBD> {
1033    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
1034        Self {
1035            output_dimension: OutputDimension::zero(cx),
1036            excerpt_dimension: <ExcerptDimension<MBD> as Dimension<'a, DiffTransformSummary>>::zero(
1037                cx,
1038            ),
1039        }
1040    }
1041
1042    fn add_summary(
1043        &mut self,
1044        summary: &'a DiffTransformSummary,
1045        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
1046    ) {
1047        self.output_dimension.add_summary(summary, cx);
1048        self.excerpt_dimension.add_summary(summary, cx);
1049    }
1050}
1051
1052#[derive(Clone)]
1053struct MultiBufferCursor<'a, MBD, BD> {
1054    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<MBD>>,
1055    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<MBD>>,
1056    diffs: &'a TreeMap<BufferId, DiffStateSnapshot>,
1057    cached_region: OnceCell<Option<MultiBufferRegion<'a, MBD, BD>>>,
1058}
1059
1060#[derive(Clone)]
1061struct MultiBufferRegion<'a, MBD, BD> {
1062    buffer: &'a BufferSnapshot,
1063    is_main_buffer: bool,
1064    diff_hunk_status: Option<DiffHunkStatus>,
1065    excerpt: &'a Excerpt,
1066    buffer_range: Range<BD>,
1067    range: Range<MBD>,
1068    has_trailing_newline: bool,
1069}
1070
1071struct ExcerptChunks<'a> {
1072    excerpt_id: ExcerptId,
1073    content_chunks: BufferChunks<'a>,
1074    has_footer: bool,
1075}
1076
1077#[derive(Debug)]
1078struct BufferEdit {
1079    range: Range<BufferOffset>,
1080    new_text: Arc<str>,
1081    is_insertion: bool,
1082    original_indent_column: Option<u32>,
1083    excerpt_id: ExcerptId,
1084}
1085
1086#[derive(Clone, Copy, Debug, PartialEq)]
1087enum DiffChangeKind {
1088    BufferEdited,
1089    DiffUpdated { base_changed: bool },
1090    ExpandOrCollapseHunks { expand: bool },
1091}
1092
1093#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1094pub enum ExpandExcerptDirection {
1095    Up,
1096    Down,
1097    UpAndDown,
1098}
1099
1100impl ExpandExcerptDirection {
1101    pub fn should_expand_up(&self) -> bool {
1102        match self {
1103            ExpandExcerptDirection::Up => true,
1104            ExpandExcerptDirection::Down => false,
1105            ExpandExcerptDirection::UpAndDown => true,
1106        }
1107    }
1108
1109    pub fn should_expand_down(&self) -> bool {
1110        match self {
1111            ExpandExcerptDirection::Up => false,
1112            ExpandExcerptDirection::Down => true,
1113            ExpandExcerptDirection::UpAndDown => true,
1114        }
1115    }
1116}
1117
1118#[derive(Clone, Debug, PartialEq)]
1119pub struct IndentGuide {
1120    pub buffer_id: BufferId,
1121    pub start_row: MultiBufferRow,
1122    pub end_row: MultiBufferRow,
1123    pub depth: u32,
1124    pub tab_size: u32,
1125    pub settings: IndentGuideSettings,
1126}
1127
1128impl IndentGuide {
1129    pub fn indent_level(&self) -> u32 {
1130        self.depth * self.tab_size
1131    }
1132}
1133
1134impl MultiBuffer {
1135    pub fn new(capability: Capability) -> Self {
1136        Self::new_(
1137            capability,
1138            MultiBufferSnapshot {
1139                show_headers: true,
1140                show_deleted_hunks: true,
1141                ..MultiBufferSnapshot::default()
1142            },
1143        )
1144    }
1145
1146    pub fn without_headers(capability: Capability) -> Self {
1147        Self::new_(
1148            capability,
1149            MultiBufferSnapshot {
1150                show_deleted_hunks: true,
1151                ..MultiBufferSnapshot::default()
1152            },
1153        )
1154    }
1155
1156    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
1157        let mut this = Self::new_(
1158            buffer.read(cx).capability(),
1159            MultiBufferSnapshot {
1160                singleton: true,
1161                show_deleted_hunks: true,
1162                ..MultiBufferSnapshot::default()
1163            },
1164        );
1165        this.singleton = true;
1166        this.set_excerpts_for_path(
1167            PathKey::sorted(0),
1168            buffer.clone(),
1169            [Point::zero()..buffer.read(cx).max_point()],
1170            0,
1171            cx,
1172        );
1173        this
1174    }
1175
1176    #[inline]
1177    pub fn new_(capability: Capability, snapshot: MultiBufferSnapshot) -> Self {
1178        Self {
1179            snapshot: RefCell::new(snapshot),
1180            buffers: Default::default(),
1181            diffs: HashMap::default(),
1182            subscriptions: Topic::default(),
1183            singleton: false,
1184            capability,
1185            title: None,
1186            excerpts_by_path: Default::default(),
1187            paths_by_excerpt: Default::default(),
1188            buffer_changed_since_sync: Default::default(),
1189            history: History::default(),
1190        }
1191    }
1192
1193    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
1194        let mut buffers = BTreeMap::default();
1195        let buffer_changed_since_sync = Rc::new(Cell::new(false));
1196        for (buffer_id, buffer_state) in self.buffers.iter() {
1197            buffer_state.buffer.update(new_cx, |buffer, _| {
1198                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
1199            });
1200            buffers.insert(
1201                *buffer_id,
1202                BufferState {
1203                    buffer: buffer_state.buffer.clone(),
1204                    last_version: buffer_state.last_version.clone(),
1205                    last_non_text_state_update_count: buffer_state
1206                        .last_non_text_state_update_count
1207                        .clone(),
1208                    excerpts: buffer_state.excerpts.clone(),
1209                    _subscriptions: [
1210                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
1211                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
1212                    ],
1213                },
1214            );
1215        }
1216        let mut diff_bases = HashMap::default();
1217        for (buffer_id, diff) in self.diffs.iter() {
1218            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
1219        }
1220        Self {
1221            snapshot: RefCell::new(self.snapshot.borrow().clone()),
1222            buffers,
1223            excerpts_by_path: Default::default(),
1224            paths_by_excerpt: Default::default(),
1225            diffs: diff_bases,
1226            subscriptions: Default::default(),
1227            singleton: self.singleton,
1228            capability: self.capability,
1229            history: self.history.clone(),
1230            title: self.title.clone(),
1231            buffer_changed_since_sync,
1232        }
1233    }
1234
1235    pub fn set_group_interval(&mut self, group_interval: Duration) {
1236        self.history.set_group_interval(group_interval);
1237    }
1238
1239    pub fn with_title(mut self, title: String) -> Self {
1240        self.title = Some(title);
1241        self
1242    }
1243
1244    pub fn read_only(&self) -> bool {
1245        !self.capability.editable()
1246    }
1247
1248    pub fn capability(&self) -> Capability {
1249        self.capability
1250    }
1251
1252    /// Returns an up-to-date snapshot of the MultiBuffer.
1253    #[ztracing::instrument(skip_all)]
1254    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
1255        self.sync(cx);
1256        self.snapshot.borrow().clone()
1257    }
1258
1259    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
1260        self.sync(cx);
1261        self.snapshot.borrow()
1262    }
1263
1264    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
1265        if self.singleton {
1266            Some(self.buffers.values().next().unwrap().buffer.clone())
1267        } else {
1268            None
1269        }
1270    }
1271
1272    pub fn is_singleton(&self) -> bool {
1273        self.singleton
1274    }
1275
1276    pub fn subscribe(&mut self) -> Subscription<MultiBufferOffset> {
1277        self.subscriptions.subscribe()
1278    }
1279
1280    pub fn is_dirty(&self, cx: &App) -> bool {
1281        self.read(cx).is_dirty()
1282    }
1283
1284    pub fn has_deleted_file(&self, cx: &App) -> bool {
1285        self.read(cx).has_deleted_file()
1286    }
1287
1288    pub fn has_conflict(&self, cx: &App) -> bool {
1289        self.read(cx).has_conflict()
1290    }
1291
1292    // The `is_empty` signature doesn't match what clippy expects
1293    #[allow(clippy::len_without_is_empty)]
1294    pub fn len(&self, cx: &App) -> MultiBufferOffset {
1295        self.read(cx).len()
1296    }
1297
1298    pub fn is_empty(&self) -> bool {
1299        self.buffers.is_empty()
1300    }
1301
1302    pub fn edit<I, S, T>(
1303        &mut self,
1304        edits: I,
1305        autoindent_mode: Option<AutoindentMode>,
1306        cx: &mut Context<Self>,
1307    ) where
1308        I: IntoIterator<Item = (Range<S>, T)>,
1309        S: ToOffset,
1310        T: Into<Arc<str>>,
1311    {
1312        self.edit_internal(edits, autoindent_mode, true, cx);
1313    }
1314
1315    pub fn edit_non_coalesce<I, S, T>(
1316        &mut self,
1317        edits: I,
1318        autoindent_mode: Option<AutoindentMode>,
1319        cx: &mut Context<Self>,
1320    ) where
1321        I: IntoIterator<Item = (Range<S>, T)>,
1322        S: ToOffset,
1323        T: Into<Arc<str>>,
1324    {
1325        self.edit_internal(edits, autoindent_mode, false, cx);
1326    }
1327
1328    fn edit_internal<I, S, T>(
1329        &mut self,
1330        edits: I,
1331        autoindent_mode: Option<AutoindentMode>,
1332        coalesce_adjacent: bool,
1333        cx: &mut Context<Self>,
1334    ) where
1335        I: IntoIterator<Item = (Range<S>, T)>,
1336        S: ToOffset,
1337        T: Into<Arc<str>>,
1338    {
1339        if self.read_only() || self.buffers.is_empty() {
1340            return;
1341        }
1342        self.sync_mut(cx);
1343        let edits = edits
1344            .into_iter()
1345            .map(|(range, new_text)| {
1346                let mut range = range.start.to_offset(self.snapshot.get_mut())
1347                    ..range.end.to_offset(self.snapshot.get_mut());
1348                if range.start > range.end {
1349                    mem::swap(&mut range.start, &mut range.end);
1350                }
1351                (range, new_text.into())
1352            })
1353            .collect::<Vec<_>>();
1354
1355        return edit_internal(self, edits, autoindent_mode, coalesce_adjacent, cx);
1356
1357        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
1358        fn edit_internal(
1359            this: &mut MultiBuffer,
1360            edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1361            mut autoindent_mode: Option<AutoindentMode>,
1362            coalesce_adjacent: bool,
1363            cx: &mut Context<MultiBuffer>,
1364        ) {
1365            let original_indent_columns = match &mut autoindent_mode {
1366                Some(AutoindentMode::Block {
1367                    original_indent_columns,
1368                }) => mem::take(original_indent_columns),
1369                _ => Default::default(),
1370            };
1371
1372            let (buffer_edits, edited_excerpt_ids) = MultiBuffer::convert_edits_to_buffer_edits(
1373                edits,
1374                this.snapshot.get_mut(),
1375                &original_indent_columns,
1376            );
1377
1378            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
1379            for (buffer_id, mut edits) in buffer_edits {
1380                buffer_ids.push(buffer_id);
1381                edits.sort_by_key(|edit| edit.range.start);
1382                this.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1383                    let mut edits = edits.into_iter().peekable();
1384                    let mut insertions = Vec::new();
1385                    let mut original_indent_columns = Vec::new();
1386                    let mut deletions = Vec::new();
1387                    let empty_str: Arc<str> = Arc::default();
1388                    while let Some(BufferEdit {
1389                        mut range,
1390                        mut new_text,
1391                        mut is_insertion,
1392                        original_indent_column,
1393                        excerpt_id,
1394                    }) = edits.next()
1395                    {
1396                        while let Some(BufferEdit {
1397                            range: next_range,
1398                            is_insertion: next_is_insertion,
1399                            new_text: next_new_text,
1400                            excerpt_id: next_excerpt_id,
1401                            ..
1402                        }) = edits.peek()
1403                        {
1404                            let should_coalesce = if coalesce_adjacent {
1405                                range.end >= next_range.start
1406                            } else {
1407                                range.end > next_range.start
1408                            };
1409
1410                            if should_coalesce {
1411                                range.end = cmp::max(next_range.end, range.end);
1412                                is_insertion |= *next_is_insertion;
1413                                if excerpt_id == *next_excerpt_id {
1414                                    new_text = format!("{new_text}{next_new_text}").into();
1415                                }
1416                                edits.next();
1417                            } else {
1418                                break;
1419                            }
1420                        }
1421
1422                        if is_insertion {
1423                            original_indent_columns.push(original_indent_column);
1424                            insertions.push((
1425                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
1426                                new_text.clone(),
1427                            ));
1428                        } else if !range.is_empty() {
1429                            deletions.push((
1430                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
1431                                empty_str.clone(),
1432                            ));
1433                        }
1434                    }
1435
1436                    let deletion_autoindent_mode =
1437                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
1438                            Some(AutoindentMode::Block {
1439                                original_indent_columns: Default::default(),
1440                            })
1441                        } else {
1442                            autoindent_mode.clone()
1443                        };
1444                    let insertion_autoindent_mode =
1445                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
1446                            Some(AutoindentMode::Block {
1447                                original_indent_columns,
1448                            })
1449                        } else {
1450                            autoindent_mode.clone()
1451                        };
1452
1453                    if coalesce_adjacent {
1454                        buffer.edit(deletions, deletion_autoindent_mode, cx);
1455                        buffer.edit(insertions, insertion_autoindent_mode, cx);
1456                    } else {
1457                        buffer.edit_non_coalesce(deletions, deletion_autoindent_mode, cx);
1458                        buffer.edit_non_coalesce(insertions, insertion_autoindent_mode, cx);
1459                    }
1460                })
1461            }
1462
1463            cx.emit(Event::ExcerptsEdited {
1464                excerpt_ids: edited_excerpt_ids,
1465                buffer_ids,
1466            });
1467        }
1468    }
1469
1470    fn convert_edits_to_buffer_edits(
1471        edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1472        snapshot: &MultiBufferSnapshot,
1473        original_indent_columns: &[Option<u32>],
1474    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
1475        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
1476        let mut edited_excerpt_ids = Vec::new();
1477        let mut cursor = snapshot.cursor::<MultiBufferOffset, BufferOffset>();
1478        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
1479            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
1480
1481            cursor.seek(&range.start);
1482            let mut start_region = cursor.region().expect("start offset out of bounds");
1483            if !start_region.is_main_buffer {
1484                cursor.next();
1485                if let Some(region) = cursor.region() {
1486                    start_region = region;
1487                } else {
1488                    continue;
1489                }
1490            }
1491
1492            if range.end < start_region.range.start {
1493                continue;
1494            }
1495
1496            let start_region = start_region.clone();
1497            if range.end > start_region.range.end {
1498                cursor.seek_forward(&range.end);
1499            }
1500            let mut end_region = cursor.region().expect("end offset out of bounds");
1501            if !end_region.is_main_buffer {
1502                cursor.prev();
1503                if let Some(region) = cursor.region() {
1504                    end_region = region;
1505                } else {
1506                    continue;
1507                }
1508            }
1509
1510            if range.start > end_region.range.end {
1511                continue;
1512            }
1513
1514            let start_overshoot = range.start.saturating_sub(start_region.range.start);
1515            let end_overshoot = range.end.saturating_sub(end_region.range.start);
1516            let buffer_start = (start_region.buffer_range.start + start_overshoot)
1517                .min(start_region.buffer_range.end);
1518            let buffer_end =
1519                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
1520
1521            if start_region.excerpt.id == end_region.excerpt.id {
1522                if start_region.buffer.capability == Capability::ReadWrite
1523                    && start_region.is_main_buffer
1524                {
1525                    edited_excerpt_ids.push(start_region.excerpt.id);
1526                    buffer_edits
1527                        .entry(start_region.buffer.remote_id())
1528                        .or_default()
1529                        .push(BufferEdit {
1530                            range: buffer_start..buffer_end,
1531                            new_text,
1532                            is_insertion: true,
1533                            original_indent_column,
1534                            excerpt_id: start_region.excerpt.id,
1535                        });
1536                }
1537            } else {
1538                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
1539                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
1540                if start_region.buffer.capability == Capability::ReadWrite
1541                    && start_region.is_main_buffer
1542                {
1543                    edited_excerpt_ids.push(start_region.excerpt.id);
1544                    buffer_edits
1545                        .entry(start_region.buffer.remote_id())
1546                        .or_default()
1547                        .push(BufferEdit {
1548                            range: start_excerpt_range,
1549                            new_text: new_text.clone(),
1550                            is_insertion: true,
1551                            original_indent_column,
1552                            excerpt_id: start_region.excerpt.id,
1553                        });
1554                }
1555                let excerpt_id = end_region.excerpt.id;
1556                if end_region.buffer.capability == Capability::ReadWrite
1557                    && end_region.is_main_buffer
1558                {
1559                    edited_excerpt_ids.push(excerpt_id);
1560                    buffer_edits
1561                        .entry(end_region.buffer.remote_id())
1562                        .or_default()
1563                        .push(BufferEdit {
1564                            range: end_excerpt_range,
1565                            new_text: new_text.clone(),
1566                            is_insertion: false,
1567                            original_indent_column,
1568                            excerpt_id,
1569                        });
1570                }
1571
1572                cursor.seek(&range.start);
1573                cursor.next_excerpt();
1574                while let Some(region) = cursor.region() {
1575                    if region.excerpt.id == excerpt_id {
1576                        break;
1577                    }
1578                    if region.buffer.capability == Capability::ReadWrite && region.is_main_buffer {
1579                        edited_excerpt_ids.push(region.excerpt.id);
1580                        buffer_edits
1581                            .entry(region.buffer.remote_id())
1582                            .or_default()
1583                            .push(BufferEdit {
1584                                range: region.buffer_range.clone(),
1585                                new_text: new_text.clone(),
1586                                is_insertion: false,
1587                                original_indent_column,
1588                                excerpt_id: region.excerpt.id,
1589                            });
1590                    }
1591                    cursor.next_excerpt();
1592                }
1593            }
1594        }
1595        (buffer_edits, edited_excerpt_ids)
1596    }
1597
1598    pub fn autoindent_ranges<I, S>(&mut self, ranges: I, cx: &mut Context<Self>)
1599    where
1600        I: IntoIterator<Item = Range<S>>,
1601        S: ToOffset,
1602    {
1603        if self.read_only() || self.buffers.is_empty() {
1604            return;
1605        }
1606        self.sync_mut(cx);
1607        let empty = Arc::<str>::from("");
1608        let edits = ranges
1609            .into_iter()
1610            .map(|range| {
1611                let mut range = range.start.to_offset(self.snapshot.get_mut())
1612                    ..range.end.to_offset(&self.snapshot.get_mut());
1613                if range.start > range.end {
1614                    mem::swap(&mut range.start, &mut range.end);
1615                }
1616                (range, empty.clone())
1617            })
1618            .collect::<Vec<_>>();
1619
1620        return autoindent_ranges_internal(self, edits, cx);
1621
1622        fn autoindent_ranges_internal(
1623            this: &mut MultiBuffer,
1624            edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1625            cx: &mut Context<MultiBuffer>,
1626        ) {
1627            let (buffer_edits, edited_excerpt_ids) =
1628                MultiBuffer::convert_edits_to_buffer_edits(edits, this.snapshot.get_mut(), &[]);
1629
1630            let mut buffer_ids = Vec::new();
1631            for (buffer_id, mut edits) in buffer_edits {
1632                buffer_ids.push(buffer_id);
1633                edits.sort_unstable_by_key(|edit| edit.range.start);
1634
1635                let mut ranges: Vec<Range<BufferOffset>> = Vec::new();
1636                for edit in edits {
1637                    if let Some(last_range) = ranges.last_mut()
1638                        && edit.range.start <= last_range.end
1639                    {
1640                        last_range.end = last_range.end.max(edit.range.end);
1641                        continue;
1642                    }
1643                    ranges.push(edit.range);
1644                }
1645
1646                this.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1647                    buffer.autoindent_ranges(ranges, cx);
1648                })
1649            }
1650
1651            cx.emit(Event::ExcerptsEdited {
1652                excerpt_ids: edited_excerpt_ids,
1653                buffer_ids,
1654            });
1655        }
1656    }
1657
1658    pub fn set_active_selections(
1659        &self,
1660        selections: &[Selection<Anchor>],
1661        line_mode: bool,
1662        cursor_shape: CursorShape,
1663        cx: &mut Context<Self>,
1664    ) {
1665        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1666            Default::default();
1667        let snapshot = self.read(cx);
1668        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1669        for selection in selections {
1670            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1671            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1672
1673            cursor.seek(&Some(start_locator), Bias::Left);
1674            while let Some(excerpt) = cursor.item()
1675                && excerpt.locator <= *end_locator
1676            {
1677                let mut start = excerpt.range.context.start;
1678                let mut end = excerpt.range.context.end;
1679                if excerpt.id == selection.start.excerpt_id {
1680                    start = selection.start.text_anchor;
1681                }
1682                if excerpt.id == selection.end.excerpt_id {
1683                    end = selection.end.text_anchor;
1684                }
1685                selections_by_buffer
1686                    .entry(excerpt.buffer_id)
1687                    .or_default()
1688                    .push(Selection {
1689                        id: selection.id,
1690                        start,
1691                        end,
1692                        reversed: selection.reversed,
1693                        goal: selection.goal,
1694                    });
1695
1696                cursor.next();
1697            }
1698        }
1699
1700        for (buffer_id, buffer_state) in self.buffers.iter() {
1701            if !selections_by_buffer.contains_key(buffer_id) {
1702                buffer_state
1703                    .buffer
1704                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1705            }
1706        }
1707
1708        for (buffer_id, mut selections) in selections_by_buffer {
1709            self.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1710                selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1711                let mut selections = selections.into_iter().peekable();
1712                let merged_selections = Arc::from_iter(iter::from_fn(|| {
1713                    let mut selection = selections.next()?;
1714                    while let Some(next_selection) = selections.peek() {
1715                        if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1716                            let next_selection = selections.next().unwrap();
1717                            if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1718                                selection.end = next_selection.end;
1719                            }
1720                        } else {
1721                            break;
1722                        }
1723                    }
1724                    Some(selection)
1725                }));
1726                buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1727            });
1728        }
1729    }
1730
1731    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1732        for buffer in self.buffers.values() {
1733            buffer
1734                .buffer
1735                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1736        }
1737    }
1738
1739    #[instrument(skip_all)]
1740    fn merge_excerpt_ranges<'a>(
1741        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1742    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1743        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1744        let mut counts: Vec<usize> = Vec::new();
1745        for range in expanded_ranges {
1746            if let Some(last_range) = merged_ranges.last_mut() {
1747                assert!(
1748                    last_range.context.start <= range.context.start,
1749                    "ranges must be sorted: {last_range:?} <= {range:?}"
1750                );
1751                if last_range.context.end >= range.context.start
1752                    || last_range.context.end.row + 1 == range.context.start.row
1753                {
1754                    last_range.context.end = range.context.end.max(last_range.context.end);
1755                    *counts.last_mut().unwrap() += 1;
1756                    continue;
1757                }
1758            }
1759            merged_ranges.push(range.clone());
1760            counts.push(1);
1761        }
1762        (merged_ranges, counts)
1763    }
1764
1765    pub fn insert_excerpts_after<O>(
1766        &mut self,
1767        prev_excerpt_id: ExcerptId,
1768        buffer: Entity<Buffer>,
1769        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1770        cx: &mut Context<Self>,
1771    ) -> Vec<ExcerptId>
1772    where
1773        O: text::ToOffset,
1774    {
1775        let mut ids = Vec::new();
1776        let mut next_excerpt_id =
1777            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1778                last_entry.id.0 + 1
1779            } else {
1780                1
1781            };
1782        self.insert_excerpts_with_ids_after(
1783            prev_excerpt_id,
1784            buffer,
1785            ranges.into_iter().map(|range| {
1786                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1787                ids.push(id);
1788                (id, range)
1789            }),
1790            cx,
1791        );
1792        ids
1793    }
1794
1795    pub fn insert_excerpts_with_ids_after<O>(
1796        &mut self,
1797        prev_excerpt_id: ExcerptId,
1798        buffer: Entity<Buffer>,
1799        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1800        cx: &mut Context<Self>,
1801    ) where
1802        O: text::ToOffset,
1803    {
1804        assert_eq!(self.history.transaction_depth(), 0);
1805        let mut ranges = ranges.into_iter().peekable();
1806        if ranges.peek().is_none() {
1807            return Default::default();
1808        }
1809
1810        self.sync_mut(cx);
1811
1812        let buffer_snapshot = buffer.read(cx).snapshot();
1813        let buffer_id = buffer_snapshot.remote_id();
1814
1815        let buffer_state = self.buffers.entry(buffer_id).or_insert_with(|| {
1816            self.buffer_changed_since_sync.replace(true);
1817            buffer.update(cx, |buffer, _| {
1818                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1819            });
1820            BufferState {
1821                last_version: RefCell::new(buffer_snapshot.version().clone()),
1822                last_non_text_state_update_count: Cell::new(
1823                    buffer_snapshot.non_text_state_update_count(),
1824                ),
1825                excerpts: Default::default(),
1826                _subscriptions: [
1827                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1828                    cx.subscribe(&buffer, Self::on_buffer_event),
1829                ],
1830                buffer: buffer.clone(),
1831            }
1832        });
1833
1834        let mut snapshot = self.snapshot.get_mut();
1835
1836        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1837        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1838        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1839        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1840        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1841
1842        let edit_start = ExcerptDimension(new_excerpts.summary().text.len);
1843        new_excerpts.update_last(
1844            |excerpt| {
1845                excerpt.has_trailing_newline = true;
1846            },
1847            (),
1848        );
1849
1850        let next_locator = if let Some(excerpt) = cursor.item() {
1851            excerpt.locator.clone()
1852        } else {
1853            Locator::max()
1854        };
1855
1856        let mut excerpts = Vec::new();
1857        let buffer_snapshot = Arc::new(buffer_snapshot);
1858        while let Some((id, range)) = ranges.next() {
1859            let locator = Locator::between(&prev_locator, &next_locator);
1860            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1861                buffer_state.excerpts.insert(ix, locator.clone());
1862            }
1863            let range = ExcerptRange {
1864                context: buffer_snapshot.anchor_before(&range.context.start)
1865                    ..buffer_snapshot.anchor_after(&range.context.end),
1866                primary: buffer_snapshot.anchor_before(&range.primary.start)
1867                    ..buffer_snapshot.anchor_after(&range.primary.end),
1868            };
1869            excerpts.push((id, range.clone()));
1870            let excerpt = Excerpt::new(
1871                id,
1872                locator.clone(),
1873                buffer_id,
1874                buffer_snapshot.clone(),
1875                range,
1876                ranges.peek().is_some() || cursor.item().is_some(),
1877            );
1878            new_excerpts.push(excerpt, ());
1879            prev_locator = locator.clone();
1880
1881            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1882                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1883            }
1884            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
1885        }
1886        snapshot
1887            .buffer_locators
1888            .insert(buffer_id, buffer_state.excerpts.iter().cloned().collect());
1889
1890        let edit_end = ExcerptDimension(new_excerpts.summary().text.len);
1891
1892        let suffix = cursor.suffix();
1893        let changed_trailing_excerpt = suffix.is_empty();
1894        new_excerpts.append(suffix, ());
1895        drop(cursor);
1896        snapshot.excerpts = new_excerpts;
1897        snapshot.excerpt_ids = new_excerpt_ids;
1898        if changed_trailing_excerpt {
1899            snapshot.trailing_excerpt_update_count += 1;
1900        }
1901
1902        let edits = Self::sync_diff_transforms(
1903            &mut snapshot,
1904            vec![Edit {
1905                old: edit_start..edit_start,
1906                new: edit_start..edit_end,
1907            }],
1908            DiffChangeKind::BufferEdited,
1909        );
1910        if !edits.is_empty() {
1911            self.subscriptions.publish(edits);
1912        }
1913
1914        cx.emit(Event::Edited {
1915            edited_buffer: None,
1916            is_local: true,
1917        });
1918        cx.emit(Event::ExcerptsAdded {
1919            buffer,
1920            predecessor: prev_excerpt_id,
1921            excerpts,
1922        });
1923        cx.notify();
1924    }
1925
1926    pub fn clear(&mut self, cx: &mut Context<Self>) {
1927        self.sync_mut(cx);
1928        let ids = self.excerpt_ids();
1929        let removed_buffer_ids = std::mem::take(&mut self.buffers).into_keys().collect();
1930        self.excerpts_by_path.clear();
1931        self.paths_by_excerpt.clear();
1932        let MultiBufferSnapshot {
1933            excerpts,
1934            buffer_locators,
1935            diffs: _,
1936            diff_transforms: _,
1937            non_text_state_update_count: _,
1938            edit_count: _,
1939            is_dirty,
1940            has_deleted_file,
1941            has_conflict,
1942            has_inverted_diff,
1943            singleton: _,
1944            excerpt_ids: _,
1945            replaced_excerpts,
1946            trailing_excerpt_update_count,
1947            all_diff_hunks_expanded: _,
1948            show_deleted_hunks: _,
1949            use_extended_diff_range: _,
1950            show_headers: _,
1951        } = self.snapshot.get_mut();
1952        buffer_locators.clear();
1953        let start = ExcerptDimension(MultiBufferOffset::ZERO);
1954        let prev_len = ExcerptDimension(excerpts.summary().text.len);
1955        *excerpts = Default::default();
1956        *trailing_excerpt_update_count += 1;
1957        *is_dirty = false;
1958        *has_deleted_file = false;
1959        *has_conflict = false;
1960        *has_inverted_diff = false;
1961        match Arc::get_mut(replaced_excerpts) {
1962            Some(replaced_excerpts) => replaced_excerpts.clear(),
1963            None => *replaced_excerpts = Default::default(),
1964        }
1965
1966        let edits = Self::sync_diff_transforms(
1967            self.snapshot.get_mut(),
1968            vec![Edit {
1969                old: start..prev_len,
1970                new: start..start,
1971            }],
1972            DiffChangeKind::BufferEdited,
1973        );
1974        if !edits.is_empty() {
1975            self.subscriptions.publish(edits);
1976        }
1977        cx.emit(Event::Edited {
1978            edited_buffer: None,
1979            is_local: true,
1980        });
1981        cx.emit(Event::ExcerptsRemoved {
1982            ids,
1983            removed_buffer_ids,
1984        });
1985        cx.notify();
1986    }
1987
1988    #[ztracing::instrument(skip_all)]
1989    pub fn excerpts_for_buffer(
1990        &self,
1991        buffer_id: BufferId,
1992        cx: &App,
1993    ) -> Vec<(ExcerptId, Arc<BufferSnapshot>, ExcerptRange<text::Anchor>)> {
1994        let mut excerpts = Vec::new();
1995        let snapshot = self.read(cx);
1996        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1997        if let Some(locators) = snapshot.buffer_locators.get(&buffer_id) {
1998            for locator in &**locators {
1999                cursor.seek_forward(&Some(locator), Bias::Left);
2000                if let Some(excerpt) = cursor.item()
2001                    && excerpt.locator == *locator
2002                {
2003                    excerpts.push((excerpt.id, excerpt.buffer.clone(), excerpt.range.clone()));
2004                }
2005            }
2006        }
2007
2008        excerpts
2009    }
2010
2011    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2012        let snapshot = self.read(cx);
2013        let mut excerpts = snapshot
2014            .excerpts
2015            .cursor::<Dimensions<Option<&Locator>, ExcerptPoint>>(());
2016        let mut diff_transforms = snapshot
2017            .diff_transforms
2018            .cursor::<Dimensions<ExcerptPoint, OutputDimension<Point>>>(());
2019        diff_transforms.next();
2020        let locators = snapshot
2021            .buffer_locators
2022            .get(&buffer_id)
2023            .into_iter()
2024            .flat_map(|v| &**v);
2025        let mut result = Vec::new();
2026        for locator in locators {
2027            excerpts.seek_forward(&Some(locator), Bias::Left);
2028            if let Some(excerpt) = excerpts.item()
2029                && excerpt.locator == *locator
2030            {
2031                let excerpt_start = excerpts.start().1;
2032                let excerpt_end = excerpt_start + excerpt.text_summary.lines;
2033
2034                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2035                let overshoot = excerpt_start - diff_transforms.start().0;
2036                let start = diff_transforms.start().1 + overshoot;
2037
2038                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2039                let overshoot = excerpt_end - diff_transforms.start().0;
2040                let end = diff_transforms.start().1 + overshoot;
2041
2042                result.push(start.0..end.0)
2043            }
2044        }
2045        result
2046    }
2047
2048    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2049        self.snapshot
2050            .borrow()
2051            .excerpts
2052            .iter()
2053            .map(|entry| entry.buffer_id)
2054            .collect()
2055    }
2056
2057    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2058        let snapshot = self.snapshot.borrow();
2059        let mut ids = Vec::with_capacity(snapshot.excerpts.summary().count);
2060        ids.extend(snapshot.excerpts.iter().map(|entry| entry.id));
2061        ids
2062    }
2063
2064    pub fn excerpt_containing(
2065        &self,
2066        position: impl ToOffset,
2067        cx: &App,
2068    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2069        let snapshot = self.read(cx);
2070        let offset = position.to_offset(&snapshot);
2071
2072        let mut cursor = snapshot.cursor::<MultiBufferOffset, BufferOffset>();
2073        cursor.seek(&offset);
2074        cursor
2075            .excerpt()
2076            .or_else(|| snapshot.excerpts.last())
2077            .map(|excerpt| {
2078                (
2079                    excerpt.id,
2080                    self.buffers.get(&excerpt.buffer_id).unwrap().buffer.clone(),
2081                    excerpt.range.context.clone(),
2082                )
2083            })
2084    }
2085
2086    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2087        if let Some(buffer_id) = anchor.text_anchor.buffer_id {
2088            self.buffer(buffer_id)
2089        } else {
2090            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2091            Some(buffer)
2092        }
2093    }
2094
2095    // If point is at the end of the buffer, the last excerpt is returned
2096    pub fn point_to_buffer_offset<T: ToOffset>(
2097        &self,
2098        point: T,
2099        cx: &App,
2100    ) -> Option<(Entity<Buffer>, BufferOffset)> {
2101        let snapshot = self.read(cx);
2102        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2103        Some((
2104            self.buffers.get(&buffer.remote_id())?.buffer.clone(),
2105            offset,
2106        ))
2107    }
2108
2109    // If point is at the end of the buffer, the last excerpt is returned
2110    pub fn point_to_buffer_point<T: ToPoint>(
2111        &self,
2112        point: T,
2113        cx: &App,
2114    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2115        let snapshot = self.read(cx);
2116        let (buffer, point, is_main_buffer) =
2117            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2118        Some((
2119            self.buffers.get(&buffer.remote_id())?.buffer.clone(),
2120            point,
2121            is_main_buffer,
2122        ))
2123    }
2124
2125    pub fn buffer_point_to_anchor(
2126        &self,
2127        // todo(lw): We shouldn't need this?
2128        buffer: &Entity<Buffer>,
2129        point: Point,
2130        cx: &App,
2131    ) -> Option<Anchor> {
2132        let mut found = None;
2133        let snapshot = buffer.read(cx).snapshot();
2134        for (excerpt_id, _, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2135            let start = range.context.start.to_point(&snapshot);
2136            let end = range.context.end.to_point(&snapshot);
2137            if start <= point && point < end {
2138                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2139                break;
2140            }
2141            if point < start {
2142                found = Some((start, excerpt_id));
2143            }
2144            if point >= end {
2145                found = Some((end, excerpt_id));
2146            }
2147        }
2148
2149        found.map(|(point, excerpt_id)| {
2150            let text_anchor = snapshot.anchor_after(point);
2151            Anchor::in_buffer(excerpt_id, text_anchor)
2152        })
2153    }
2154
2155    pub fn buffer_anchor_to_anchor(
2156        &self,
2157        // todo(lw): We shouldn't need this?
2158        buffer: &Entity<Buffer>,
2159        anchor: text::Anchor,
2160        cx: &App,
2161    ) -> Option<Anchor> {
2162        let snapshot = buffer.read(cx).snapshot();
2163        for (excerpt_id, _, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2164            if range.context.start.cmp(&anchor, &snapshot).is_le()
2165                && range.context.end.cmp(&anchor, &snapshot).is_ge()
2166            {
2167                return Some(Anchor::in_buffer(excerpt_id, anchor));
2168            }
2169        }
2170
2171        None
2172    }
2173
2174    pub fn merge_excerpts(
2175        &mut self,
2176        excerpt_ids: &[ExcerptId],
2177        cx: &mut Context<Self>,
2178    ) -> ExcerptId {
2179        debug_assert!(!excerpt_ids.is_empty());
2180        if excerpt_ids.len() == 1 {
2181            return excerpt_ids[0];
2182        }
2183
2184        let snapshot = self.snapshot(cx);
2185
2186        let first_range = snapshot
2187            .context_range_for_excerpt(excerpt_ids[0])
2188            .expect("first excerpt must exist");
2189        let last_range = snapshot
2190            .context_range_for_excerpt(*excerpt_ids.last().unwrap())
2191            .expect("last excerpt must exist");
2192
2193        let union_range = first_range.start..last_range.end;
2194
2195        drop(snapshot);
2196
2197        self.resize_excerpt(excerpt_ids[0], union_range, cx);
2198        let removed = &excerpt_ids[1..];
2199        for &excerpt_id in removed {
2200            if let Some(path) = self.paths_by_excerpt.get(&excerpt_id) {
2201                if let Some(excerpt_list) = self.excerpts_by_path.get_mut(path) {
2202                    excerpt_list.retain(|id| *id != excerpt_id);
2203                    if excerpt_list.is_empty() {
2204                        let path = path.clone();
2205                        self.excerpts_by_path.remove(&path);
2206                    }
2207                }
2208            }
2209        }
2210        self.remove_excerpts(removed.iter().copied(), cx);
2211
2212        excerpt_ids[0]
2213    }
2214
2215    pub fn remove_excerpts(
2216        &mut self,
2217        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2218        cx: &mut Context<Self>,
2219    ) {
2220        self.sync_mut(cx);
2221        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2222        if ids.is_empty() {
2223            return;
2224        }
2225        self.buffer_changed_since_sync.replace(true);
2226
2227        let mut snapshot = self.snapshot.get_mut();
2228        let mut new_excerpts = SumTree::default();
2229        let mut cursor = snapshot
2230            .excerpts
2231            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2232        let mut edits = Vec::new();
2233        let mut excerpt_ids = ids.iter().copied().peekable();
2234        let mut removed_buffer_ids = Vec::new();
2235        let mut removed_excerpts_for_buffers = HashSet::default();
2236
2237        while let Some(excerpt_id) = excerpt_ids.next() {
2238            self.paths_by_excerpt.remove(&excerpt_id);
2239            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2240            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2241            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2242
2243            if let Some(mut excerpt) = cursor.item() {
2244                if excerpt.id != excerpt_id {
2245                    continue;
2246                }
2247                let mut old_start = cursor.start().1;
2248
2249                // Skip over the removed excerpt.
2250                'remove_excerpts: loop {
2251                    if let Some(buffer_state) = self.buffers.get_mut(&excerpt.buffer_id) {
2252                        removed_excerpts_for_buffers.insert(excerpt.buffer_id);
2253                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2254                        if buffer_state.excerpts.is_empty() {
2255                            log::debug!(
2256                                "removing buffer and diff for buffer {}",
2257                                excerpt.buffer_id
2258                            );
2259                            self.buffers.remove(&excerpt.buffer_id);
2260                            removed_buffer_ids.push(excerpt.buffer_id);
2261                        }
2262                    }
2263                    cursor.next();
2264
2265                    // Skip over any subsequent excerpts that are also removed.
2266                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2267                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2268                        if let Some(next_excerpt) = cursor.item()
2269                            && next_excerpt.locator == *next_locator
2270                        {
2271                            excerpt_ids.next();
2272                            excerpt = next_excerpt;
2273                            continue 'remove_excerpts;
2274                        }
2275                    }
2276
2277                    break;
2278                }
2279
2280                // When removing the last excerpt, remove the trailing newline from
2281                // the previous excerpt.
2282                if cursor.item().is_none() && old_start > MultiBufferOffset::ZERO {
2283                    old_start -= 1;
2284                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2285                }
2286
2287                // Push an edit for the removal of this run of excerpts.
2288                let old_end = cursor.start().1;
2289                let new_start = ExcerptDimension(new_excerpts.summary().text.len);
2290                edits.push(Edit {
2291                    old: old_start..old_end,
2292                    new: new_start..new_start,
2293                });
2294            }
2295        }
2296        let suffix = cursor.suffix();
2297        let changed_trailing_excerpt = suffix.is_empty();
2298        new_excerpts.append(suffix, ());
2299        drop(cursor);
2300        for buffer_id in removed_excerpts_for_buffers {
2301            match self.buffers.get(&buffer_id) {
2302                Some(buffer_state) => {
2303                    snapshot
2304                        .buffer_locators
2305                        .insert(buffer_id, buffer_state.excerpts.iter().cloned().collect());
2306                }
2307                None => {
2308                    snapshot.buffer_locators.remove(&buffer_id);
2309                }
2310            }
2311        }
2312        snapshot.excerpts = new_excerpts;
2313        for buffer_id in &removed_buffer_ids {
2314            self.diffs.remove(buffer_id);
2315            snapshot.diffs.remove(buffer_id);
2316        }
2317
2318        // Recalculate has_inverted_diff after removing diffs
2319        if !removed_buffer_ids.is_empty() {
2320            snapshot.has_inverted_diff = snapshot
2321                .diffs
2322                .iter()
2323                .any(|(_, diff)| diff.main_buffer.is_some());
2324        }
2325
2326        if changed_trailing_excerpt {
2327            snapshot.trailing_excerpt_update_count += 1;
2328        }
2329
2330        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2331        if !edits.is_empty() {
2332            self.subscriptions.publish(edits);
2333        }
2334        cx.emit(Event::Edited {
2335            edited_buffer: None,
2336            is_local: true,
2337        });
2338        cx.emit(Event::ExcerptsRemoved {
2339            ids,
2340            removed_buffer_ids,
2341        });
2342        cx.notify();
2343    }
2344
2345    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2346        &self,
2347        anchors: Anchors,
2348        cx: &mut Context<Self>,
2349    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2350        let mut error = None;
2351        let mut futures = Vec::new();
2352        for anchor in anchors {
2353            if let Some(buffer_id) = anchor.text_anchor.buffer_id {
2354                if let Some(buffer) = self.buffers.get(&buffer_id) {
2355                    buffer.buffer.update(cx, |buffer, _| {
2356                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2357                    });
2358                } else {
2359                    error = Some(anyhow!(
2360                        "buffer {buffer_id} is not part of this multi-buffer"
2361                    ));
2362                    break;
2363                }
2364            }
2365        }
2366        async move {
2367            if let Some(error) = error {
2368                Err(error)?;
2369            }
2370            for future in futures {
2371                future.await?;
2372            }
2373            Ok(())
2374        }
2375    }
2376
2377    pub fn text_anchor_for_position<T: ToOffset>(
2378        &self,
2379        position: T,
2380        cx: &App,
2381    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2382        let snapshot = self.read(cx);
2383        let anchor = snapshot.anchor_before(position);
2384        let buffer = self
2385            .buffers
2386            .get(&anchor.text_anchor.buffer_id?)?
2387            .buffer
2388            .clone();
2389        Some((buffer, anchor.text_anchor))
2390    }
2391
2392    fn on_buffer_event(
2393        &mut self,
2394        buffer: Entity<Buffer>,
2395        event: &language::BufferEvent,
2396        cx: &mut Context<Self>,
2397    ) {
2398        use language::BufferEvent;
2399        let buffer_id = buffer.read(cx).remote_id();
2400        cx.emit(match event {
2401            &BufferEvent::Edited { is_local } => Event::Edited {
2402                edited_buffer: Some(buffer),
2403                is_local,
2404            },
2405            BufferEvent::DirtyChanged => Event::DirtyChanged,
2406            BufferEvent::Saved => Event::Saved,
2407            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2408            BufferEvent::Reloaded => Event::Reloaded,
2409            BufferEvent::LanguageChanged(has_language) => {
2410                Event::LanguageChanged(buffer_id, *has_language)
2411            }
2412            BufferEvent::Reparsed => Event::Reparsed(buffer_id),
2413            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2414            BufferEvent::CapabilityChanged => {
2415                self.capability = buffer.read(cx).capability();
2416                return;
2417            }
2418            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2419        });
2420    }
2421
2422    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2423        let diff = diff.read(cx);
2424        let buffer_id = diff.buffer_id;
2425        let diff = DiffStateSnapshot {
2426            diff: diff.snapshot(cx),
2427            main_buffer: None,
2428        };
2429        self.snapshot.get_mut().diffs.insert(buffer_id, diff);
2430    }
2431
2432    fn inverted_buffer_diff_language_changed(
2433        &mut self,
2434        diff: Entity<BufferDiff>,
2435        main_buffer: Entity<language::Buffer>,
2436        cx: &mut Context<Self>,
2437    ) {
2438        let base_text_buffer_id = diff.read(cx).base_text_buffer().read(cx).remote_id();
2439        let main_buffer_snapshot = main_buffer.read(cx).snapshot();
2440        let diff = diff.read(cx);
2441        let diff = DiffStateSnapshot {
2442            diff: diff.snapshot(cx),
2443            main_buffer: Some(main_buffer_snapshot),
2444        };
2445        self.snapshot
2446            .get_mut()
2447            .diffs
2448            .insert(base_text_buffer_id, diff);
2449    }
2450
2451    fn buffer_diff_changed(
2452        &mut self,
2453        diff: Entity<BufferDiff>,
2454        range: Range<text::Anchor>,
2455        cx: &mut Context<Self>,
2456    ) {
2457        self.sync_mut(cx);
2458
2459        let diff = diff.read(cx);
2460        let buffer_id = diff.buffer_id;
2461
2462        let new_diff = DiffStateSnapshot {
2463            diff: diff.snapshot(cx),
2464            main_buffer: None,
2465        };
2466        let mut snapshot = self.snapshot.get_mut();
2467        let base_text_changed = snapshot
2468            .diffs
2469            .get(&buffer_id)
2470            .is_none_or(|old_diff| !new_diff.base_texts_definitely_eq(old_diff));
2471        snapshot.diffs.insert_or_replace(buffer_id, new_diff);
2472
2473        let Some(buffer_state) = self.buffers.get(&buffer_id) else {
2474            return;
2475        };
2476
2477        let buffer = buffer_state.buffer.read(cx);
2478        let diff_change_range = range.to_offset(buffer);
2479
2480        let excerpt_edits = snapshot.excerpt_edits_for_diff_change(buffer_state, diff_change_range);
2481        let edits = Self::sync_diff_transforms(
2482            &mut snapshot,
2483            excerpt_edits,
2484            DiffChangeKind::DiffUpdated {
2485                base_changed: base_text_changed,
2486            },
2487        );
2488        if !edits.is_empty() {
2489            self.subscriptions.publish(edits);
2490        }
2491        cx.emit(Event::Edited {
2492            edited_buffer: None,
2493            is_local: true,
2494        });
2495    }
2496
2497    fn inverted_buffer_diff_changed(
2498        &mut self,
2499        diff: Entity<BufferDiff>,
2500        main_buffer: Entity<language::Buffer>,
2501        diff_change_range: Option<Range<usize>>,
2502        cx: &mut Context<Self>,
2503    ) {
2504        self.sync_mut(cx);
2505
2506        let base_text_buffer_id = diff.read(cx).base_text_buffer().read(cx).remote_id();
2507        let Some(buffer_state) = self.buffers.get(&base_text_buffer_id) else {
2508            return;
2509        };
2510
2511        let main_buffer_snapshot = main_buffer.read(cx).snapshot();
2512        let diff = diff.read(cx);
2513        let new_diff = DiffStateSnapshot {
2514            diff: diff.snapshot(cx),
2515            main_buffer: Some(main_buffer_snapshot),
2516        };
2517        let mut snapshot = self.snapshot.get_mut();
2518        snapshot
2519            .diffs
2520            .insert_or_replace(base_text_buffer_id, new_diff);
2521
2522        let Some(diff_change_range) = diff_change_range else {
2523            return;
2524        };
2525
2526        let excerpt_edits = snapshot.excerpt_edits_for_diff_change(buffer_state, diff_change_range);
2527        let edits = Self::sync_diff_transforms(
2528            &mut snapshot,
2529            excerpt_edits,
2530            DiffChangeKind::DiffUpdated {
2531                // We don't read this field for inverted diffs.
2532                base_changed: false,
2533            },
2534        );
2535        if !edits.is_empty() {
2536            self.subscriptions.publish(edits);
2537        }
2538        cx.emit(Event::Edited {
2539            edited_buffer: None,
2540            is_local: true,
2541        });
2542    }
2543
2544    pub fn all_buffers_iter(&self) -> impl Iterator<Item = Entity<Buffer>> {
2545        self.buffers.values().map(|state| state.buffer.clone())
2546    }
2547
2548    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2549        self.all_buffers_iter().collect()
2550    }
2551
2552    pub fn all_buffer_ids_iter(&self) -> impl Iterator<Item = BufferId> {
2553        self.buffers.keys().copied()
2554    }
2555
2556    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2557        self.all_buffer_ids_iter().collect()
2558    }
2559
2560    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2561        self.buffers
2562            .get(&buffer_id)
2563            .map(|state| state.buffer.clone())
2564    }
2565
2566    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2567        self.point_to_buffer_offset(point, cx)
2568            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2569    }
2570
2571    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2572        let buffer_id = self
2573            .snapshot
2574            .borrow()
2575            .excerpts
2576            .first()
2577            .map(|excerpt| excerpt.buffer.remote_id());
2578        buffer_id
2579            .and_then(|buffer_id| self.buffer(buffer_id))
2580            .map(|buffer| {
2581                let buffer = buffer.read(cx);
2582                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2583            })
2584            .unwrap_or_else(move || self.language_settings_at(MultiBufferOffset::default(), cx))
2585    }
2586
2587    pub fn language_settings_at<'a, T: ToOffset>(
2588        &'a self,
2589        point: T,
2590        cx: &'a App,
2591    ) -> Cow<'a, LanguageSettings> {
2592        let mut language = None;
2593        let mut file = None;
2594        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2595            let buffer = buffer.read(cx);
2596            language = buffer.language_at(offset);
2597            file = buffer.file();
2598        }
2599        language_settings(language.map(|l| l.name()), file, cx)
2600    }
2601
2602    pub fn for_each_buffer(&self, f: &mut dyn FnMut(&Entity<Buffer>)) {
2603        self.buffers.values().for_each(|state| f(&state.buffer))
2604    }
2605
2606    pub fn explicit_title(&self) -> Option<&str> {
2607        self.title.as_deref()
2608    }
2609
2610    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2611        if let Some(title) = self.title.as_ref() {
2612            return title.into();
2613        }
2614
2615        if let Some(buffer) = self.as_singleton() {
2616            let buffer = buffer.read(cx);
2617
2618            if let Some(file) = buffer.file() {
2619                return file.file_name(cx).into();
2620            }
2621
2622            if let Some(title) = self.buffer_content_title(buffer) {
2623                return title;
2624            }
2625        };
2626
2627        "untitled".into()
2628    }
2629
2630    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2631        let mut is_leading_whitespace = true;
2632        let mut count = 0;
2633        let mut prev_was_space = false;
2634        let mut title = String::new();
2635
2636        for ch in buffer.snapshot().chars() {
2637            if is_leading_whitespace && ch.is_whitespace() {
2638                continue;
2639            }
2640
2641            is_leading_whitespace = false;
2642
2643            if ch == '\n' || count >= 40 {
2644                break;
2645            }
2646
2647            if ch.is_whitespace() {
2648                if !prev_was_space {
2649                    title.push(' ');
2650                    count += 1;
2651                    prev_was_space = true;
2652                }
2653            } else {
2654                title.push(ch);
2655                count += 1;
2656                prev_was_space = false;
2657            }
2658        }
2659
2660        let title = title.trim_end().to_string();
2661
2662        if title.is_empty() {
2663            return None;
2664        }
2665
2666        Some(title.into())
2667    }
2668
2669    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2670        self.title = Some(title);
2671        cx.notify();
2672    }
2673
2674    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2675    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2676        for buffer_state in self.buffers.values() {
2677            buffer_state
2678                .buffer
2679                .update(cx, |buffer, _cx| buffer.refresh_preview());
2680        }
2681    }
2682
2683    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2684    pub fn preserve_preview(&self, cx: &App) -> bool {
2685        self.buffers
2686            .values()
2687            .all(|state| state.buffer.read(cx).preserve_preview())
2688    }
2689
2690    #[cfg(any(test, feature = "test-support"))]
2691    pub fn is_parsing(&self, cx: &App) -> bool {
2692        self.as_singleton().unwrap().read(cx).is_parsing()
2693    }
2694
2695    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2696        let buffer_id = diff.read(cx).buffer_id;
2697
2698        if let Some(existing_diff) = self.diff_for(buffer_id)
2699            && diff.entity_id() == existing_diff.entity_id()
2700        {
2701            return;
2702        }
2703
2704        self.buffer_diff_changed(
2705            diff.clone(),
2706            text::Anchor::min_max_range_for_buffer(buffer_id),
2707            cx,
2708        );
2709        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2710    }
2711
2712    pub fn add_inverted_diff(
2713        &mut self,
2714        diff: Entity<BufferDiff>,
2715        main_buffer: Entity<language::Buffer>,
2716        cx: &mut Context<Self>,
2717    ) {
2718        let snapshot = diff.read(cx).base_text(cx);
2719        let base_text_buffer_id = snapshot.remote_id();
2720        let diff_change_range = 0..snapshot.len();
2721        self.snapshot.get_mut().has_inverted_diff = true;
2722        self.inverted_buffer_diff_changed(
2723            diff.clone(),
2724            main_buffer.clone(),
2725            Some(diff_change_range),
2726            cx,
2727        );
2728        self.diffs.insert(
2729            base_text_buffer_id,
2730            DiffState::new_inverted(diff, main_buffer, cx),
2731        );
2732    }
2733
2734    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2735        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2736    }
2737
2738    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2739        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2740    }
2741
2742    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2743        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2744    }
2745
2746    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2747        self.snapshot.get_mut().all_diff_hunks_expanded = true;
2748        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2749    }
2750
2751    pub fn all_diff_hunks_expanded(&self) -> bool {
2752        self.snapshot.borrow().all_diff_hunks_expanded
2753    }
2754
2755    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2756        self.snapshot.get_mut().all_diff_hunks_expanded = false;
2757        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2758    }
2759
2760    pub fn set_show_deleted_hunks(&mut self, show: bool, cx: &mut Context<Self>) {
2761        self.snapshot.get_mut().show_deleted_hunks = show;
2762
2763        self.sync_mut(cx);
2764
2765        let old_len = self.snapshot.borrow().len();
2766
2767        let ranges = std::iter::once((Point::zero()..Point::MAX, ExcerptId::max()));
2768        let _ = self.expand_or_collapse_diff_hunks_inner(ranges, true, cx);
2769
2770        let new_len = self.snapshot.borrow().len();
2771
2772        self.subscriptions.publish(vec![Edit {
2773            old: MultiBufferOffset(0)..old_len,
2774            new: MultiBufferOffset(0)..new_len,
2775        }]);
2776
2777        cx.emit(Event::DiffHunksToggled);
2778        cx.emit(Event::Edited {
2779            edited_buffer: None,
2780            is_local: true,
2781        });
2782    }
2783
2784    pub fn set_use_extended_diff_range(&mut self, use_extended: bool, _cx: &mut Context<Self>) {
2785        self.snapshot.get_mut().use_extended_diff_range = use_extended;
2786    }
2787
2788    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2789        self.read(cx)
2790            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2791            .nth(1)
2792            .is_some()
2793    }
2794
2795    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2796        let snapshot = self.read(cx);
2797        let mut cursor = snapshot.diff_transforms.cursor::<MultiBufferOffset>(());
2798        let offset_range = range.to_offset(&snapshot);
2799        cursor.seek(&offset_range.start, Bias::Left);
2800        while let Some(item) = cursor.item() {
2801            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2802                break;
2803            }
2804            if item.hunk_info().is_some() {
2805                return true;
2806            }
2807            cursor.next();
2808        }
2809        false
2810    }
2811
2812    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2813        let snapshot = self.read(cx);
2814        let mut cursor = snapshot.diff_transforms.cursor::<MultiBufferOffset>(());
2815        for range in ranges {
2816            let range = range.to_point(&snapshot);
2817            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2818            let end = (snapshot.point_to_offset(Point::new(range.end.row + 1, 0)) + 1usize)
2819                .min(snapshot.len());
2820            cursor.seek(&start, Bias::Right);
2821            while let Some(item) = cursor.item() {
2822                if *cursor.start() >= end {
2823                    break;
2824                }
2825                if item.hunk_info().is_some() {
2826                    return true;
2827                }
2828                cursor.next();
2829            }
2830        }
2831        false
2832    }
2833
2834    pub fn expand_or_collapse_diff_hunks_inner(
2835        &mut self,
2836        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2837        expand: bool,
2838        cx: &mut Context<Self>,
2839    ) -> Vec<Edit<MultiBufferOffset>> {
2840        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2841            return Vec::new();
2842        }
2843        self.sync_mut(cx);
2844        let mut snapshot = self.snapshot.get_mut();
2845        let mut excerpt_edits = Vec::new();
2846        let mut last_hunk_row = None;
2847        for (range, end_excerpt_id) in ranges {
2848            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2849                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2850                    continue;
2851                }
2852                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2853                    continue;
2854                }
2855                let start = Anchor::in_buffer(diff_hunk.excerpt_id, diff_hunk.buffer_range.start);
2856                let end = Anchor::in_buffer(diff_hunk.excerpt_id, diff_hunk.buffer_range.end);
2857                let start = snapshot.excerpt_offset_for_anchor(&start);
2858                let end = snapshot.excerpt_offset_for_anchor(&end);
2859                last_hunk_row = Some(diff_hunk.row_range.start);
2860                excerpt_edits.push(text::Edit {
2861                    old: start..end,
2862                    new: start..end,
2863                });
2864            }
2865        }
2866
2867        Self::sync_diff_transforms(
2868            &mut snapshot,
2869            excerpt_edits,
2870            DiffChangeKind::ExpandOrCollapseHunks { expand },
2871        )
2872    }
2873
2874    pub fn expand_or_collapse_diff_hunks(
2875        &mut self,
2876        ranges: Vec<Range<Anchor>>,
2877        expand: bool,
2878        cx: &mut Context<Self>,
2879    ) {
2880        let snapshot = self.snapshot.borrow().clone();
2881        let ranges = ranges.iter().map(move |range| {
2882            let end_excerpt_id = range.end.excerpt_id;
2883            let range = range.to_point(&snapshot);
2884            let mut peek_end = range.end;
2885            if range.end.row < snapshot.max_row().0 {
2886                peek_end = Point::new(range.end.row + 1, 0);
2887            };
2888            (range.start..peek_end, end_excerpt_id)
2889        });
2890        let edits = self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2891        if !edits.is_empty() {
2892            self.subscriptions.publish(edits);
2893        }
2894        cx.emit(Event::DiffHunksToggled);
2895        cx.emit(Event::Edited {
2896            edited_buffer: None,
2897            is_local: true,
2898        });
2899    }
2900
2901    pub fn resize_excerpt(
2902        &mut self,
2903        id: ExcerptId,
2904        range: Range<text::Anchor>,
2905        cx: &mut Context<Self>,
2906    ) {
2907        self.sync_mut(cx);
2908
2909        let mut snapshot = self.snapshot.get_mut();
2910        let locator = snapshot.excerpt_locator_for_id(id);
2911        let mut new_excerpts = SumTree::default();
2912        let mut cursor = snapshot
2913            .excerpts
2914            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2915        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2916
2917        let prefix = cursor.slice(&Some(locator), Bias::Left);
2918        new_excerpts.append(prefix, ());
2919
2920        let mut excerpt = cursor.item().unwrap().clone();
2921        let old_text_len = excerpt.text_summary.len;
2922
2923        excerpt.range.context.start = range.start;
2924        excerpt.range.context.end = range.end;
2925        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2926
2927        excerpt.text_summary = excerpt
2928            .buffer
2929            .text_summary_for_range(excerpt.range.context.clone());
2930
2931        let new_start_offset = ExcerptDimension(new_excerpts.summary().text.len);
2932        let old_start_offset = cursor.start().1;
2933        let new_text_len = excerpt.text_summary.len;
2934        let edit = Edit {
2935            old: old_start_offset..old_start_offset + old_text_len,
2936            new: new_start_offset..new_start_offset + new_text_len,
2937        };
2938
2939        if let Some(last_edit) = edits.last_mut() {
2940            if last_edit.old.end == edit.old.start {
2941                last_edit.old.end = edit.old.end;
2942                last_edit.new.end = edit.new.end;
2943            } else {
2944                edits.push(edit);
2945            }
2946        } else {
2947            edits.push(edit);
2948        }
2949
2950        new_excerpts.push(excerpt, ());
2951
2952        cursor.next();
2953
2954        new_excerpts.append(cursor.suffix(), ());
2955
2956        drop(cursor);
2957        snapshot.excerpts = new_excerpts;
2958
2959        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2960        if !edits.is_empty() {
2961            self.subscriptions.publish(edits);
2962        }
2963        cx.emit(Event::Edited {
2964            edited_buffer: None,
2965            is_local: true,
2966        });
2967        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2968        cx.notify();
2969    }
2970
2971    pub fn expand_excerpts(
2972        &mut self,
2973        ids: impl IntoIterator<Item = ExcerptId>,
2974        line_count: u32,
2975        direction: ExpandExcerptDirection,
2976        cx: &mut Context<Self>,
2977    ) {
2978        if line_count == 0 {
2979            return;
2980        }
2981        self.sync_mut(cx);
2982        if !self.excerpts_by_path.is_empty() {
2983            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2984            return;
2985        }
2986        let mut snapshot = self.snapshot.get_mut();
2987
2988        let ids = ids.into_iter().collect::<Vec<_>>();
2989        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2990        let mut new_excerpts = SumTree::default();
2991        let mut cursor = snapshot
2992            .excerpts
2993            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2994        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2995
2996        for locator in &locators {
2997            let prefix = cursor.slice(&Some(locator), Bias::Left);
2998            new_excerpts.append(prefix, ());
2999
3000            let mut excerpt = cursor.item().unwrap().clone();
3001            let old_text_len = excerpt.text_summary.len;
3002
3003            let up_line_count = if direction.should_expand_up() {
3004                line_count
3005            } else {
3006                0
3007            };
3008
3009            let start_row = excerpt
3010                .range
3011                .context
3012                .start
3013                .to_point(&excerpt.buffer)
3014                .row
3015                .saturating_sub(up_line_count);
3016            let start_point = Point::new(start_row, 0);
3017            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
3018
3019            let down_line_count = if direction.should_expand_down() {
3020                line_count
3021            } else {
3022                0
3023            };
3024
3025            let mut end_point = excerpt.buffer.clip_point(
3026                excerpt.range.context.end.to_point(&excerpt.buffer)
3027                    + Point::new(down_line_count, 0),
3028                Bias::Left,
3029            );
3030            end_point.column = excerpt.buffer.line_len(end_point.row);
3031            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
3032            excerpt.max_buffer_row = end_point.row;
3033
3034            excerpt.text_summary = excerpt
3035                .buffer
3036                .text_summary_for_range(excerpt.range.context.clone());
3037
3038            let new_start_offset = ExcerptDimension(new_excerpts.summary().text.len);
3039            let old_start_offset = cursor.start().1;
3040            let new_text_len = excerpt.text_summary.len;
3041            let edit = Edit {
3042                old: old_start_offset..old_start_offset + old_text_len,
3043                new: new_start_offset..new_start_offset + new_text_len,
3044            };
3045
3046            if let Some(last_edit) = edits.last_mut() {
3047                if last_edit.old.end == edit.old.start {
3048                    last_edit.old.end = edit.old.end;
3049                    last_edit.new.end = edit.new.end;
3050                } else {
3051                    edits.push(edit);
3052                }
3053            } else {
3054                edits.push(edit);
3055            }
3056
3057            new_excerpts.push(excerpt, ());
3058
3059            cursor.next();
3060        }
3061
3062        new_excerpts.append(cursor.suffix(), ());
3063
3064        drop(cursor);
3065        snapshot.excerpts = new_excerpts;
3066
3067        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3068        if !edits.is_empty() {
3069            self.subscriptions.publish(edits);
3070        }
3071        cx.emit(Event::Edited {
3072            edited_buffer: None,
3073            is_local: true,
3074        });
3075        cx.emit(Event::ExcerptsExpanded { ids });
3076        cx.notify();
3077    }
3078
3079    #[ztracing::instrument(skip_all)]
3080    fn sync(&self, cx: &App) {
3081        let changed = self.buffer_changed_since_sync.replace(false);
3082        if !changed {
3083            return;
3084        }
3085        let edits = Self::sync_from_buffer_changes(
3086            &mut self.snapshot.borrow_mut(),
3087            &self.buffers,
3088            &self.diffs,
3089            cx,
3090        );
3091        if !edits.is_empty() {
3092            self.subscriptions.publish(edits);
3093        }
3094    }
3095
3096    fn sync_mut(&mut self, cx: &App) {
3097        let changed = self.buffer_changed_since_sync.replace(false);
3098        if !changed {
3099            return;
3100        }
3101        let edits =
3102            Self::sync_from_buffer_changes(self.snapshot.get_mut(), &self.buffers, &self.diffs, cx);
3103
3104        if !edits.is_empty() {
3105            self.subscriptions.publish(edits);
3106        }
3107    }
3108
3109    fn sync_from_buffer_changes(
3110        snapshot: &mut MultiBufferSnapshot,
3111        buffers: &BTreeMap<BufferId, BufferState>,
3112        diffs: &HashMap<BufferId, DiffState>,
3113        cx: &App,
3114    ) -> Vec<Edit<MultiBufferOffset>> {
3115        let MultiBufferSnapshot {
3116            excerpts,
3117            buffer_locators: _,
3118            diffs: buffer_diff,
3119            diff_transforms: _,
3120            non_text_state_update_count,
3121            edit_count,
3122            is_dirty,
3123            has_deleted_file,
3124            has_conflict,
3125            has_inverted_diff: _,
3126            singleton: _,
3127            excerpt_ids: _,
3128            replaced_excerpts: _,
3129            trailing_excerpt_update_count: _,
3130            all_diff_hunks_expanded: _,
3131            show_deleted_hunks: _,
3132            use_extended_diff_range: _,
3133            show_headers: _,
3134        } = snapshot;
3135        *is_dirty = false;
3136        *has_deleted_file = false;
3137        *has_conflict = false;
3138
3139        if !diffs.is_empty() {
3140            let mut diffs_to_add = Vec::new();
3141            for (id, diff) in diffs {
3142                // For inverted diffs, we excerpt the diff base texts in the multibuffer
3143                // and use the diff hunk base text ranges to compute diff transforms.
3144                // Those base text ranges are usize, so make sure if the base text changed
3145                // we also update the diff snapshot so that we don't use stale offsets
3146                if buffer_diff.get(id).is_none_or(|existing_diff| {
3147                    if existing_diff.main_buffer.is_none() {
3148                        return false;
3149                    }
3150                    let base_text = diff.diff.read(cx).base_text_buffer().read(cx);
3151                    base_text.remote_id() != existing_diff.base_text().remote_id()
3152                        || base_text
3153                            .version()
3154                            .changed_since(existing_diff.base_text().version())
3155                }) {
3156                    if diffs_to_add.capacity() == 0 {
3157                        // we'd rather overallocate than reallocate as buffer diffs are quite big
3158                        // meaning re-allocations will be fairly expensive
3159                        diffs_to_add.reserve(diffs.len());
3160                    }
3161                    diffs_to_add.push((*id, diff.snapshot(cx)));
3162                }
3163            }
3164            buffer_diff.extend(diffs_to_add);
3165        }
3166
3167        let mut excerpts_to_edit = Vec::new();
3168        let mut non_text_state_updated = false;
3169        let mut edited = false;
3170        for buffer_state in buffers.values() {
3171            let buffer = buffer_state.buffer.read(cx);
3172            let version = buffer.version();
3173            let non_text_state_update_count = buffer.non_text_state_update_count();
3174
3175            let buffer_edited = version.changed_since(&buffer_state.last_version.borrow());
3176            let buffer_non_text_state_updated =
3177                non_text_state_update_count > buffer_state.last_non_text_state_update_count.get();
3178            if buffer_edited || buffer_non_text_state_updated {
3179                *buffer_state.last_version.borrow_mut() = version;
3180                buffer_state
3181                    .last_non_text_state_update_count
3182                    .set(non_text_state_update_count);
3183                excerpts_to_edit.extend(
3184                    buffer_state
3185                        .excerpts
3186                        .iter()
3187                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3188                );
3189            }
3190
3191            edited |= buffer_edited;
3192            non_text_state_updated |= buffer_non_text_state_updated;
3193            *is_dirty |= buffer.is_dirty();
3194            *has_deleted_file |= buffer
3195                .file()
3196                .is_some_and(|file| file.disk_state().is_deleted());
3197            *has_conflict |= buffer.has_conflict();
3198        }
3199        if edited {
3200            *edit_count += 1;
3201        }
3202        if non_text_state_updated {
3203            *non_text_state_update_count += 1;
3204        }
3205
3206        excerpts_to_edit.sort_unstable_by_key(|&(locator, _, _)| locator);
3207
3208        let mut edits = Vec::new();
3209        let mut new_excerpts = SumTree::default();
3210        let mut cursor = excerpts.cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3211
3212        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3213            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3214            let old_excerpt = cursor.item().unwrap();
3215            let buffer = buffer.read(cx);
3216            let buffer_id = buffer.remote_id();
3217            let mut new_excerpt;
3218            if buffer_edited {
3219                edits.extend(
3220                    buffer
3221                        .edits_since_in_range::<usize>(
3222                            old_excerpt.buffer.version(),
3223                            old_excerpt.range.context.clone(),
3224                        )
3225                        .map(|edit| {
3226                            let excerpt_old_start = cursor.start().1;
3227                            let excerpt_new_start =
3228                                ExcerptDimension(new_excerpts.summary().text.len);
3229                            let old_start = excerpt_old_start + edit.old.start;
3230                            let old_end = excerpt_old_start + edit.old.end;
3231                            let new_start = excerpt_new_start + edit.new.start;
3232                            let new_end = excerpt_new_start + edit.new.end;
3233                            Edit {
3234                                old: old_start..old_end,
3235                                new: new_start..new_end,
3236                            }
3237                        }),
3238                );
3239
3240                new_excerpt = Excerpt::new(
3241                    old_excerpt.id,
3242                    locator.clone(),
3243                    buffer_id,
3244                    Arc::new(buffer.snapshot()),
3245                    old_excerpt.range.clone(),
3246                    old_excerpt.has_trailing_newline,
3247                );
3248            } else {
3249                new_excerpt = old_excerpt.clone();
3250                new_excerpt.buffer = Arc::new(buffer.snapshot());
3251            }
3252
3253            new_excerpts.push(new_excerpt, ());
3254            cursor.next();
3255        }
3256        new_excerpts.append(cursor.suffix(), ());
3257
3258        drop(cursor);
3259        *excerpts = new_excerpts;
3260
3261        Self::sync_diff_transforms(snapshot, edits, DiffChangeKind::BufferEdited)
3262    }
3263
3264    fn sync_diff_transforms(
3265        snapshot: &mut MultiBufferSnapshot,
3266        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3267        change_kind: DiffChangeKind,
3268    ) -> Vec<Edit<MultiBufferOffset>> {
3269        if excerpt_edits.is_empty() {
3270            return vec![];
3271        }
3272
3273        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3274        let mut old_diff_transforms = snapshot
3275            .diff_transforms
3276            .cursor::<Dimensions<ExcerptOffset, MultiBufferOffset>>(());
3277        let mut new_diff_transforms = SumTree::default();
3278        let mut old_expanded_hunks = HashSet::default();
3279        let mut output_edits = Vec::new();
3280        let mut output_delta = 0_isize;
3281        let mut at_transform_boundary = true;
3282        let mut end_of_current_insert = None;
3283
3284        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3285        while let Some(edit) = excerpt_edits.next() {
3286            excerpts.seek_forward(&edit.new.start, Bias::Right);
3287            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3288                excerpts.prev();
3289            }
3290
3291            // Keep any transforms that are before the edit.
3292            if at_transform_boundary {
3293                at_transform_boundary = false;
3294                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3295                Self::append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3296                if let Some(transform) = old_diff_transforms.item()
3297                    && old_diff_transforms.end().0 == edit.old.start
3298                    && old_diff_transforms.start().0 < edit.old.start
3299                {
3300                    Self::push_diff_transform(&mut new_diff_transforms, transform.clone());
3301                    old_diff_transforms.next();
3302                }
3303            }
3304
3305            // Compute the start of the edit in output coordinates.
3306            let edit_start_overshoot = edit.old.start - old_diff_transforms.start().0;
3307            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3308            let edit_new_start =
3309                MultiBufferOffset((edit_old_start.0 as isize + output_delta) as usize);
3310
3311            let changed_diff_hunks = Self::recompute_diff_transforms_for_edit(
3312                &edit,
3313                &mut excerpts,
3314                &mut old_diff_transforms,
3315                &mut new_diff_transforms,
3316                &mut end_of_current_insert,
3317                &mut old_expanded_hunks,
3318                snapshot,
3319                change_kind,
3320            );
3321
3322            // Compute the end of the edit in output coordinates.
3323            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3324            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3325            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot;
3326            let edit_new_end = new_diff_transforms.summary().output.len + edit_new_end_overshoot;
3327            let output_edit = Edit {
3328                old: edit_old_start..edit_old_end,
3329                new: edit_new_start..edit_new_end,
3330            };
3331
3332            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3333            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3334            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3335                output_edits.push(output_edit);
3336            }
3337
3338            // If this is the last edit that intersects the current diff transform,
3339            // then recreate the content up to the end of this transform, to prepare
3340            // for reusing additional slices of the old transforms.
3341            if excerpt_edits
3342                .peek()
3343                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3344            {
3345                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3346                    && match old_diff_transforms.item() {
3347                        Some(DiffTransform::BufferContent {
3348                            inserted_hunk_info: Some(hunk),
3349                            ..
3350                        }) => excerpts.item().is_some_and(|excerpt| {
3351                            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id)
3352                                && diff.main_buffer.is_some()
3353                            {
3354                                return true;
3355                            }
3356                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3357                        }),
3358                        _ => true,
3359                    };
3360
3361                let mut excerpt_offset = edit.new.end;
3362                if !keep_next_old_transform {
3363                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3364                    old_diff_transforms.next();
3365                }
3366
3367                old_expanded_hunks.clear();
3368                Self::push_buffer_content_transform(
3369                    snapshot,
3370                    &mut new_diff_transforms,
3371                    excerpt_offset,
3372                    end_of_current_insert,
3373                );
3374                at_transform_boundary = true;
3375            }
3376        }
3377
3378        // Keep any transforms that are after the last edit.
3379        Self::append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3380
3381        // Ensure there's always at least one buffer content transform.
3382        if new_diff_transforms.is_empty() {
3383            new_diff_transforms.push(
3384                DiffTransform::BufferContent {
3385                    summary: Default::default(),
3386                    inserted_hunk_info: None,
3387                },
3388                (),
3389            );
3390        }
3391
3392        drop(old_diff_transforms);
3393        drop(excerpts);
3394        snapshot.diff_transforms = new_diff_transforms;
3395        snapshot.edit_count += 1;
3396
3397        #[cfg(any(test, feature = "test-support"))]
3398        snapshot.check_invariants();
3399        output_edits
3400    }
3401
3402    fn recompute_diff_transforms_for_edit(
3403        edit: &Edit<ExcerptOffset>,
3404        excerpts: &mut Cursor<Excerpt, ExcerptOffset>,
3405        old_diff_transforms: &mut Cursor<
3406            DiffTransform,
3407            Dimensions<ExcerptOffset, MultiBufferOffset>,
3408        >,
3409        new_diff_transforms: &mut SumTree<DiffTransform>,
3410        end_of_current_insert: &mut Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3411        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3412        snapshot: &MultiBufferSnapshot,
3413        change_kind: DiffChangeKind,
3414    ) -> bool {
3415        log::trace!(
3416            "recomputing diff transform for edit {:?} => {:?}",
3417            edit.old.start..edit.old.end,
3418            edit.new.start..edit.new.end
3419        );
3420
3421        // Record which hunks were previously expanded.
3422        while let Some(item) = old_diff_transforms.item() {
3423            if let Some(hunk_info) = item.hunk_info() {
3424                log::trace!(
3425                    "previously expanded hunk at {:?}",
3426                    old_diff_transforms.start()
3427                );
3428                old_expanded_hunks.insert(hunk_info);
3429            }
3430            if old_diff_transforms.end().0 > edit.old.end {
3431                break;
3432            }
3433            old_diff_transforms.next();
3434        }
3435
3436        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3437        // For inverted diffs, hunks are always shown, so we can't skip this.
3438        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3439        if old_expanded_hunks.is_empty()
3440            && change_kind == DiffChangeKind::BufferEdited
3441            && !all_diff_hunks_expanded
3442            && !snapshot.has_inverted_diff
3443        {
3444            return false;
3445        }
3446
3447        // Visit each excerpt that intersects the edit.
3448        let mut did_expand_hunks = false;
3449        while let Some(excerpt) = excerpts.item() {
3450            // Recompute the expanded hunks in the portion of the excerpt that
3451            // intersects the edit.
3452            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3453                let buffer = &excerpt.buffer;
3454                let excerpt_start = *excerpts.start();
3455                let excerpt_end = excerpt_start + excerpt.text_summary.len;
3456                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3457                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3458                let edit_buffer_start =
3459                    excerpt_buffer_start + edit.new.start.saturating_sub(excerpt_start);
3460                let edit_buffer_end =
3461                    excerpt_buffer_start + edit.new.end.saturating_sub(excerpt_start);
3462                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3463
3464                if let Some(main_buffer) = &diff.main_buffer {
3465                    for hunk in diff.hunks_intersecting_base_text_range(
3466                        edit_buffer_start..edit_buffer_end,
3467                        main_buffer,
3468                    ) {
3469                        did_expand_hunks = true;
3470                        let hunk_buffer_range = hunk.diff_base_byte_range.clone();
3471                        if hunk_buffer_range.start < excerpt_buffer_start {
3472                            log::trace!("skipping hunk that starts before excerpt");
3473                            continue;
3474                        }
3475                        hunk_buffer_range.end.to_point(&excerpt.buffer);
3476                        let hunk_excerpt_start = excerpt_start
3477                            + hunk_buffer_range.start.saturating_sub(excerpt_buffer_start);
3478                        let hunk_excerpt_end = excerpt_end
3479                            .min(excerpt_start + (hunk_buffer_range.end - excerpt_buffer_start));
3480                        Self::push_buffer_content_transform(
3481                            snapshot,
3482                            new_diff_transforms,
3483                            hunk_excerpt_start,
3484                            *end_of_current_insert,
3485                        );
3486                        if !hunk_buffer_range.is_empty() {
3487                            let hunk_info = DiffTransformHunkInfo {
3488                                excerpt_id: excerpt.id,
3489                                hunk_start_anchor: hunk.buffer_range.start,
3490                                hunk_secondary_status: hunk.secondary_status,
3491                                is_logically_deleted: true,
3492                            };
3493                            *end_of_current_insert =
3494                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3495                        }
3496                    }
3497                } else {
3498                    let edit_anchor_range = buffer.anchor_before(edit_buffer_start)
3499                        ..buffer.anchor_after(edit_buffer_end);
3500                    for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3501                        if hunk.is_created_file() && !all_diff_hunks_expanded {
3502                            continue;
3503                        }
3504
3505                        let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3506                        if hunk_buffer_range.start < excerpt_buffer_start {
3507                            log::trace!("skipping hunk that starts before excerpt");
3508                            continue;
3509                        }
3510
3511                        let hunk_info = DiffTransformHunkInfo {
3512                            excerpt_id: excerpt.id,
3513                            hunk_start_anchor: hunk.buffer_range.start,
3514                            hunk_secondary_status: hunk.secondary_status,
3515                            is_logically_deleted: false,
3516                        };
3517
3518                        let hunk_excerpt_start = excerpt_start
3519                            + hunk_buffer_range.start.saturating_sub(excerpt_buffer_start);
3520                        let hunk_excerpt_end = excerpt_end
3521                            .min(excerpt_start + (hunk_buffer_range.end - excerpt_buffer_start));
3522
3523                        Self::push_buffer_content_transform(
3524                            snapshot,
3525                            new_diff_transforms,
3526                            hunk_excerpt_start,
3527                            *end_of_current_insert,
3528                        );
3529
3530                        // For every existing hunk, determine if it was previously expanded
3531                        // and if it should currently be expanded.
3532                        let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3533                        let should_expand_hunk = match &change_kind {
3534                            DiffChangeKind::DiffUpdated { base_changed: true } => {
3535                                was_previously_expanded || all_diff_hunks_expanded
3536                            }
3537                            DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3538                                let intersects = hunk_buffer_range.is_empty()
3539                                    || hunk_buffer_range.end > edit_buffer_start;
3540                                if *expand {
3541                                    intersects || was_previously_expanded || all_diff_hunks_expanded
3542                                } else {
3543                                    !intersects
3544                                        && (was_previously_expanded || all_diff_hunks_expanded)
3545                                }
3546                            }
3547                            _ => was_previously_expanded || all_diff_hunks_expanded,
3548                        };
3549
3550                        if should_expand_hunk {
3551                            did_expand_hunks = true;
3552                            log::trace!(
3553                                "expanding hunk {:?}, excerpt:{:?}",
3554                                hunk_excerpt_start..hunk_excerpt_end,
3555                                excerpt.id
3556                            );
3557
3558                            if !hunk.diff_base_byte_range.is_empty()
3559                                && hunk_buffer_range.start >= edit_buffer_start
3560                                && hunk_buffer_range.start <= excerpt_buffer_end
3561                                && snapshot.show_deleted_hunks
3562                            {
3563                                let base_text = diff.base_text();
3564                                let mut text_cursor =
3565                                    base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3566                                let mut base_text_summary = text_cursor
3567                                    .summary::<TextSummary>(hunk.diff_base_byte_range.end);
3568
3569                                let mut has_trailing_newline = false;
3570                                if base_text_summary.last_line_chars > 0 {
3571                                    base_text_summary += TextSummary::newline();
3572                                    has_trailing_newline = true;
3573                                }
3574
3575                                new_diff_transforms.push(
3576                                    DiffTransform::DeletedHunk {
3577                                        base_text_byte_range: hunk.diff_base_byte_range.clone(),
3578                                        summary: base_text_summary,
3579                                        buffer_id: excerpt.buffer_id,
3580                                        hunk_info,
3581                                        has_trailing_newline,
3582                                    },
3583                                    (),
3584                                );
3585                            }
3586
3587                            if !hunk_buffer_range.is_empty() {
3588                                *end_of_current_insert =
3589                                    Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3590                            }
3591                        }
3592                    }
3593                }
3594            }
3595
3596            if excerpts.end() <= edit.new.end {
3597                excerpts.next();
3598            } else {
3599                break;
3600            }
3601        }
3602
3603        did_expand_hunks || !old_expanded_hunks.is_empty()
3604    }
3605
3606    fn append_diff_transforms(
3607        new_transforms: &mut SumTree<DiffTransform>,
3608        subtree: SumTree<DiffTransform>,
3609    ) {
3610        if let Some(DiffTransform::BufferContent {
3611            inserted_hunk_info,
3612            summary,
3613        }) = subtree.first()
3614            && Self::extend_last_buffer_content_transform(
3615                new_transforms,
3616                *inserted_hunk_info,
3617                *summary,
3618            )
3619        {
3620            let mut cursor = subtree.cursor::<()>(());
3621            cursor.next();
3622            cursor.next();
3623            new_transforms.append(cursor.suffix(), ());
3624            return;
3625        }
3626        new_transforms.append(subtree, ());
3627    }
3628
3629    fn push_diff_transform(new_transforms: &mut SumTree<DiffTransform>, transform: DiffTransform) {
3630        if let DiffTransform::BufferContent {
3631            inserted_hunk_info: inserted_hunk_anchor,
3632            summary,
3633        } = transform
3634            && Self::extend_last_buffer_content_transform(
3635                new_transforms,
3636                inserted_hunk_anchor,
3637                summary,
3638            )
3639        {
3640            return;
3641        }
3642        new_transforms.push(transform, ());
3643    }
3644
3645    fn push_buffer_content_transform(
3646        old_snapshot: &MultiBufferSnapshot,
3647        new_transforms: &mut SumTree<DiffTransform>,
3648        end_offset: ExcerptOffset,
3649        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3650    ) {
3651        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3652            (end_offset.min(insertion_end_offset), Some(hunk_info))
3653        });
3654        let unchanged_region = [(end_offset, None)];
3655
3656        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3657        {
3658            let start_offset = new_transforms.summary().excerpt_len();
3659            if end_offset <= start_offset {
3660                continue;
3661            }
3662            let summary_to_add = old_snapshot
3663                .text_summary_for_excerpt_offset_range::<MBTextSummary>(start_offset..end_offset);
3664
3665            if !Self::extend_last_buffer_content_transform(
3666                new_transforms,
3667                inserted_hunk_info,
3668                summary_to_add,
3669            ) {
3670                new_transforms.push(
3671                    DiffTransform::BufferContent {
3672                        summary: summary_to_add,
3673                        inserted_hunk_info,
3674                    },
3675                    (),
3676                )
3677            }
3678        }
3679    }
3680
3681    fn extend_last_buffer_content_transform(
3682        new_transforms: &mut SumTree<DiffTransform>,
3683        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3684        summary_to_add: MBTextSummary,
3685    ) -> bool {
3686        let mut did_extend = false;
3687        new_transforms.update_last(
3688            |last_transform| {
3689                if let DiffTransform::BufferContent {
3690                    summary,
3691                    inserted_hunk_info: inserted_hunk_anchor,
3692                } = last_transform
3693                    && *inserted_hunk_anchor == new_inserted_hunk_info
3694                {
3695                    *summary += summary_to_add;
3696                    did_extend = true;
3697                }
3698            },
3699            (),
3700        );
3701        did_extend
3702    }
3703
3704    pub fn toggle_single_diff_hunk(&mut self, range: Range<Anchor>, cx: &mut Context<Self>) {
3705        let snapshot = self.snapshot(cx);
3706        let excerpt_id = range.end.excerpt_id;
3707        let point_range = range.to_point(&snapshot);
3708        let expand = !self.single_hunk_is_expanded(range, cx);
3709        let edits =
3710            self.expand_or_collapse_diff_hunks_inner([(point_range, excerpt_id)], expand, cx);
3711        if !edits.is_empty() {
3712            self.subscriptions.publish(edits);
3713        }
3714        cx.emit(Event::DiffHunksToggled);
3715        cx.emit(Event::Edited {
3716            edited_buffer: None,
3717            is_local: true,
3718        });
3719    }
3720}
3721
3722fn build_excerpt_ranges(
3723    ranges: impl IntoIterator<Item = Range<Point>>,
3724    context_line_count: u32,
3725    buffer_snapshot: &BufferSnapshot,
3726) -> Vec<ExcerptRange<Point>> {
3727    ranges
3728        .into_iter()
3729        .map(|range| {
3730            let start_row = range.start.row.saturating_sub(context_line_count);
3731            let start = Point::new(start_row, 0);
3732            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3733            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3734            ExcerptRange {
3735                context: start..end,
3736                primary: range,
3737            }
3738        })
3739        .collect()
3740}
3741
3742#[cfg(any(test, feature = "test-support"))]
3743impl MultiBuffer {
3744    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3745        let buffer = cx.new(|cx| Buffer::local(text, cx));
3746        cx.new(|cx| Self::singleton(buffer, cx))
3747    }
3748
3749    pub fn build_multi<const COUNT: usize>(
3750        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3751        cx: &mut gpui::App,
3752    ) -> Entity<Self> {
3753        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3754        for (ix, (text, ranges)) in excerpts.into_iter().enumerate() {
3755            let buffer = cx.new(|cx| Buffer::local(text, cx));
3756            let snapshot = buffer.read(cx).snapshot();
3757            let excerpt_ranges = ranges
3758                .into_iter()
3759                .map(ExcerptRange::new)
3760                .collect::<Vec<_>>();
3761            multi.update(cx, |multi, cx| {
3762                multi.set_excerpt_ranges_for_path(
3763                    PathKey::sorted(ix as u64),
3764                    buffer,
3765                    &snapshot,
3766                    excerpt_ranges,
3767                    cx,
3768                )
3769            });
3770        }
3771
3772        multi
3773    }
3774
3775    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3776        cx.new(|cx| Self::singleton(buffer, cx))
3777    }
3778
3779    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3780        cx.new(|cx| {
3781            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3782            let mutation_count = rng.random_range(1..=5);
3783            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3784            multibuffer
3785        })
3786    }
3787
3788    pub fn randomly_edit(
3789        &mut self,
3790        rng: &mut impl rand::Rng,
3791        edit_count: usize,
3792        cx: &mut Context<Self>,
3793    ) {
3794        use util::RandomCharIter;
3795
3796        let snapshot = self.read(cx);
3797        let mut edits: Vec<(Range<MultiBufferOffset>, Arc<str>)> = Vec::new();
3798        let mut last_end = None;
3799        for _ in 0..edit_count {
3800            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3801                break;
3802            }
3803
3804            let new_start = last_end.map_or(MultiBufferOffset::ZERO, |last_end| last_end + 1usize);
3805            let end =
3806                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3807            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3808            last_end = Some(end);
3809
3810            let mut range = start..end;
3811            if rng.random_bool(0.2) {
3812                mem::swap(&mut range.start, &mut range.end);
3813            }
3814
3815            let new_text_len = rng.random_range(0..10);
3816            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3817
3818            edits.push((range, new_text.into()));
3819        }
3820        log::info!("mutating multi-buffer with {:?}", edits);
3821        drop(snapshot);
3822
3823        self.edit(edits, None, cx);
3824    }
3825
3826    pub fn randomly_edit_excerpts(
3827        &mut self,
3828        rng: &mut impl rand::Rng,
3829        mutation_count: usize,
3830        cx: &mut Context<Self>,
3831    ) {
3832        use rand::prelude::*;
3833        use std::env;
3834        use util::RandomCharIter;
3835
3836        let max_excerpts = env::var("MAX_EXCERPTS")
3837            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3838            .unwrap_or(5);
3839
3840        let mut buffers = Vec::new();
3841        for _ in 0..mutation_count {
3842            if rng.random_bool(0.05) {
3843                log::info!("Clearing multi-buffer");
3844                self.clear(cx);
3845                continue;
3846            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3847                let ids = self.excerpt_ids();
3848                let mut excerpts = HashSet::default();
3849                for _ in 0..rng.random_range(0..ids.len()) {
3850                    excerpts.extend(ids.choose(rng).copied());
3851                }
3852
3853                let line_count = rng.random_range(0..5);
3854
3855                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3856
3857                self.expand_excerpts(
3858                    excerpts.iter().cloned(),
3859                    line_count,
3860                    ExpandExcerptDirection::UpAndDown,
3861                    cx,
3862                );
3863                continue;
3864            }
3865
3866            let excerpt_ids = self.excerpt_ids();
3867            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3868                let buffer_handle = if rng.random() || self.buffers.is_empty() {
3869                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3870                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3871                    let buffer = buffers.last().unwrap().read(cx);
3872                    log::info!(
3873                        "Creating new buffer {} with text: {:?}",
3874                        buffer.remote_id(),
3875                        buffer.text()
3876                    );
3877                    buffers.last().unwrap().clone()
3878                } else {
3879                    self.buffers.values().choose(rng).unwrap().buffer.clone()
3880                };
3881
3882                let buffer = buffer_handle.read(cx);
3883                let buffer_text = buffer.text();
3884                let ranges = (0..rng.random_range(0..5))
3885                    .map(|_| {
3886                        let end_ix =
3887                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3888                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3889                        ExcerptRange::new(start_ix..end_ix)
3890                    })
3891                    .collect::<Vec<_>>();
3892                log::info!(
3893                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3894                    buffer_handle.read(cx).remote_id(),
3895                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3896                    ranges
3897                        .iter()
3898                        .map(|r| &buffer_text[r.context.clone()])
3899                        .collect::<Vec<_>>()
3900                );
3901
3902                let excerpt_id =
3903                    self.insert_excerpts_after(ExcerptId::max(), buffer_handle, ranges, cx);
3904                log::info!("Inserted with ids: {:?}", excerpt_id);
3905            } else {
3906                let remove_count = rng.random_range(1..=excerpt_ids.len());
3907                let mut excerpts_to_remove = excerpt_ids
3908                    .choose_multiple(rng, remove_count)
3909                    .cloned()
3910                    .collect::<Vec<_>>();
3911                let snapshot = self.snapshot.borrow();
3912                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3913                drop(snapshot);
3914                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3915                self.remove_excerpts(excerpts_to_remove, cx);
3916            }
3917        }
3918    }
3919
3920    pub fn randomly_mutate(
3921        &mut self,
3922        rng: &mut impl rand::Rng,
3923        mutation_count: usize,
3924        cx: &mut Context<Self>,
3925    ) {
3926        use rand::prelude::*;
3927
3928        if rng.random_bool(0.7) || self.singleton {
3929            let buffer = self
3930                .buffers
3931                .values()
3932                .choose(rng)
3933                .map(|state| state.buffer.clone());
3934
3935            if let Some(buffer) = buffer {
3936                buffer.update(cx, |buffer, cx| {
3937                    if rng.random() {
3938                        buffer.randomly_edit(rng, mutation_count, cx);
3939                    } else {
3940                        buffer.randomly_undo_redo(rng, cx);
3941                    }
3942                });
3943            } else {
3944                self.randomly_edit(rng, mutation_count, cx);
3945            }
3946        } else {
3947            self.randomly_edit_excerpts(rng, mutation_count, cx);
3948        }
3949
3950        self.check_invariants(cx);
3951    }
3952
3953    fn check_invariants(&self, cx: &App) {
3954        self.read(cx).check_invariants();
3955    }
3956}
3957
3958impl EventEmitter<Event> for MultiBuffer {}
3959
3960impl MultiBufferSnapshot {
3961    pub fn text(&self) -> String {
3962        self.chunks(MultiBufferOffset::ZERO..self.len(), false)
3963            .map(|chunk| chunk.text)
3964            .collect()
3965    }
3966
3967    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3968        self.reversed_chunks_in_range(MultiBufferOffset::ZERO..position.to_offset(self))
3969            .flat_map(|c| c.chars().rev())
3970    }
3971
3972    fn reversed_chunks_in_range(
3973        &self,
3974        range: Range<MultiBufferOffset>,
3975    ) -> ReversedMultiBufferChunks<'_> {
3976        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
3977        cursor.seek(&range.end);
3978        let current_chunks = cursor.region().as_ref().map(|region| {
3979            let start_overshoot = range.start.saturating_sub(region.range.start);
3980            let end_overshoot = range.end - region.range.start;
3981            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3982            let start = region.buffer_range.start + start_overshoot;
3983            region.buffer.reversed_chunks_in_range(start..end)
3984        });
3985        ReversedMultiBufferChunks {
3986            cursor,
3987            current_chunks,
3988            start: range.start,
3989            offset: range.end,
3990        }
3991    }
3992
3993    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3994        let offset = position.to_offset(self);
3995        self.text_for_range(offset..self.len())
3996            .flat_map(|chunk| chunk.chars())
3997    }
3998
3999    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
4000        self.chunks(range, false).map(|chunk| chunk.text)
4001    }
4002
4003    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
4004        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
4005            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
4006    }
4007
4008    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
4009    where
4010        T: ToOffset,
4011    {
4012        let position = position.to_offset(self);
4013        position == self.clip_offset(position, Bias::Left)
4014            && self
4015                .bytes_in_range(position..self.len())
4016                .flatten()
4017                .copied()
4018                .take(needle.len())
4019                .eq(needle.bytes())
4020    }
4021
4022    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
4023        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
4024    }
4025
4026    pub fn diff_hunks_in_range<T: ToPoint>(
4027        &self,
4028        range: Range<T>,
4029    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
4030        let query_range = range.start.to_point(self)..range.end.to_point(self);
4031        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
4032            let diff = self.diffs.get(&buffer.remote_id())?;
4033            let iter = if let Some(main_buffer) = &diff.main_buffer {
4034                let buffer_start = buffer.point_to_offset(buffer_range.start);
4035                let buffer_end = buffer.point_to_offset(buffer_range.end);
4036                itertools::Either::Left(
4037                    diff.hunks_intersecting_base_text_range(buffer_start..buffer_end, main_buffer)
4038                        .map(move |hunk| (hunk, buffer, true)),
4039                )
4040            } else {
4041                let buffer_start = buffer.anchor_before(buffer_range.start);
4042                let buffer_end = buffer.anchor_after(buffer_range.end);
4043                itertools::Either::Right(
4044                    diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
4045                        .map(move |hunk| (hunk, buffer, false)),
4046                )
4047            };
4048            Some(iter.filter_map(|(hunk, buffer, is_inverted)| {
4049                if hunk.is_created_file() && !self.all_diff_hunks_expanded {
4050                    return None;
4051                }
4052                let range = if is_inverted {
4053                    hunk.diff_base_byte_range.to_point(&buffer)
4054                } else {
4055                    hunk.range.clone()
4056                };
4057                Some((range, (hunk, is_inverted)))
4058            }))
4059        })
4060        .filter_map(move |(range, (hunk, is_inverted), excerpt)| {
4061            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
4062            {
4063                return None;
4064            }
4065            let end_row = if range.end.column == 0 {
4066                range.end.row
4067            } else {
4068                range.end.row + 1
4069            };
4070
4071            let word_diffs =
4072                (!hunk.base_word_diffs.is_empty() || !hunk.buffer_word_diffs.is_empty())
4073                    .then(|| {
4074                        let mut word_diffs = Vec::new();
4075
4076                        if self.show_deleted_hunks || is_inverted {
4077                            let hunk_start_offset = if is_inverted {
4078                                Anchor::in_buffer(
4079                                    excerpt.id,
4080                                    excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start),
4081                                )
4082                                .to_offset(self)
4083                            } else {
4084                                Anchor::in_buffer(excerpt.id, hunk.buffer_range.start)
4085                                    .to_offset(self)
4086                            };
4087
4088                            word_diffs.extend(hunk.base_word_diffs.iter().map(|diff| {
4089                                hunk_start_offset + diff.start..hunk_start_offset + diff.end
4090                            }));
4091                        }
4092
4093                        if !is_inverted {
4094                            word_diffs.extend(hunk.buffer_word_diffs.into_iter().map(|diff| {
4095                                Anchor::range_in_buffer(excerpt.id, diff).to_offset(self)
4096                            }));
4097                        }
4098                        word_diffs
4099                    })
4100                    .unwrap_or_default();
4101
4102            let buffer_range = if is_inverted {
4103                excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start)
4104                    ..excerpt.buffer.anchor_before(hunk.diff_base_byte_range.end)
4105            } else {
4106                hunk.buffer_range.clone()
4107            };
4108            let status_kind = if hunk.buffer_range.start == hunk.buffer_range.end {
4109                DiffHunkStatusKind::Deleted
4110            } else if hunk.diff_base_byte_range.is_empty() {
4111                DiffHunkStatusKind::Added
4112            } else {
4113                DiffHunkStatusKind::Modified
4114            };
4115            Some(MultiBufferDiffHunk {
4116                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
4117                buffer_id: excerpt.buffer_id,
4118                excerpt_id: excerpt.id,
4119                buffer_range,
4120                word_diffs,
4121                diff_base_byte_range: BufferOffset(hunk.diff_base_byte_range.start)
4122                    ..BufferOffset(hunk.diff_base_byte_range.end),
4123                status: DiffHunkStatus {
4124                    kind: status_kind,
4125                    secondary: hunk.secondary_status,
4126                },
4127            })
4128        })
4129    }
4130
4131    fn excerpts_for_range<T: ToOffset>(
4132        &self,
4133        range: Range<T>,
4134    ) -> impl Iterator<Item = &Excerpt> + '_ {
4135        let range = range.start.to_offset(self)..range.end.to_offset(self);
4136        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4137        cursor.seek(&range.start);
4138        std::iter::from_fn(move || {
4139            let region = cursor.region()?;
4140            if region.range.start > range.end
4141                || region.range.start == range.end && region.range.start > range.start
4142            {
4143                return None;
4144            }
4145            let excerpt = region.excerpt;
4146            cursor.next_excerpt_forwards();
4147            Some(excerpt)
4148        })
4149    }
4150
4151    pub fn excerpt_ids_for_range<T: ToOffset>(
4152        &self,
4153        range: Range<T>,
4154    ) -> impl Iterator<Item = ExcerptId> + '_ {
4155        self.excerpts_for_range(range).map(|excerpt| excerpt.id)
4156    }
4157
4158    pub fn buffer_ids_for_range<T: ToOffset>(
4159        &self,
4160        range: Range<T>,
4161    ) -> impl Iterator<Item = BufferId> + '_ {
4162        self.excerpts_for_range(range)
4163            .map(|excerpt| excerpt.buffer_id)
4164    }
4165
4166    /// Resolves the given [`text::Anchor`]s to [`crate::Anchor`]s if the anchor is within a visible excerpt.
4167    ///
4168    /// The passed in anchors must be ordered.
4169    pub fn text_anchors_to_visible_anchors(
4170        &self,
4171        anchors: impl IntoIterator<Item = text::Anchor>,
4172    ) -> Vec<Option<Anchor>> {
4173        let anchors = anchors.into_iter();
4174        let mut result = Vec::with_capacity(anchors.size_hint().0);
4175        let mut anchors = anchors.peekable();
4176        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
4177        'anchors: while let Some(anchor) = anchors.peek() {
4178            let Some(buffer_id) = anchor.buffer_id else {
4179                anchors.next();
4180                result.push(None);
4181                continue 'anchors;
4182            };
4183            let mut same_buffer_anchors =
4184                anchors.peeking_take_while(|a| a.buffer_id.is_some_and(|b| buffer_id == b));
4185
4186            if let Some(locators) = self.buffer_locators.get(&buffer_id) {
4187                let Some(mut next) = same_buffer_anchors.next() else {
4188                    continue 'anchors;
4189                };
4190                'excerpts: for locator in locators.iter() {
4191                    if cursor.seek_forward(&Some(locator), Bias::Left)
4192                        && let Some(excerpt) = cursor.item()
4193                    {
4194                        loop {
4195                            // anchor is before the first excerpt
4196                            if excerpt
4197                                .range
4198                                .context
4199                                .start
4200                                .cmp(&next, &excerpt.buffer)
4201                                .is_gt()
4202                            {
4203                                // so we skip it and try the next anchor
4204                                result.push(None);
4205                                match same_buffer_anchors.next() {
4206                                    Some(anchor) => next = anchor,
4207                                    None => continue 'anchors,
4208                                }
4209                            // anchor is within the excerpt
4210                            } else if excerpt
4211                                .range
4212                                .context
4213                                .end
4214                                .cmp(&next, &excerpt.buffer)
4215                                .is_ge()
4216                            {
4217                                // record it and all following anchors that are within
4218                                result.push(Some(Anchor::in_buffer(excerpt.id, next)));
4219                                result.extend(
4220                                    same_buffer_anchors
4221                                        .peeking_take_while(|a| {
4222                                            excerpt
4223                                                .range
4224                                                .context
4225                                                .end
4226                                                .cmp(a, &excerpt.buffer)
4227                                                .is_ge()
4228                                        })
4229                                        .map(|a| Some(Anchor::in_buffer(excerpt.id, a))),
4230                                );
4231                                match same_buffer_anchors.next() {
4232                                    Some(anchor) => next = anchor,
4233                                    None => continue 'anchors,
4234                                }
4235                            // anchor is after the excerpt, try the next one
4236                            } else {
4237                                continue 'excerpts;
4238                            }
4239                        }
4240                    }
4241                }
4242                // account for `next`
4243                result.push(None);
4244            }
4245            result.extend(same_buffer_anchors.map(|_| None));
4246        }
4247
4248        result
4249    }
4250
4251    pub fn ranges_to_buffer_ranges<T: ToOffset>(
4252        &self,
4253        ranges: impl Iterator<Item = Range<T>>,
4254    ) -> impl Iterator<Item = (&BufferSnapshot, Range<BufferOffset>, ExcerptId)> {
4255        ranges.flat_map(|range| {
4256            self.range_to_buffer_ranges((Bound::Included(range.start), Bound::Included(range.end)))
4257                .into_iter()
4258        })
4259    }
4260
4261    pub fn range_to_buffer_ranges<R, T>(
4262        &self,
4263        range: R,
4264    ) -> Vec<(&BufferSnapshot, Range<BufferOffset>, ExcerptId)>
4265    where
4266        R: RangeBounds<T>,
4267        T: ToOffset,
4268    {
4269        self.range_to_buffer_ranges_with_context(range)
4270            .into_iter()
4271            .map(|(buffer, range, id, _context)| (buffer, range, id))
4272            .collect()
4273    }
4274
4275    pub fn range_to_buffer_ranges_with_context<R, T>(
4276        &self,
4277        range: R,
4278    ) -> Vec<(
4279        &BufferSnapshot,
4280        Range<BufferOffset>,
4281        ExcerptId,
4282        Range<text::Anchor>,
4283    )>
4284    where
4285        R: RangeBounds<T>,
4286        T: ToOffset,
4287    {
4288        let start = match range.start_bound() {
4289            Bound::Included(start) => start.to_offset(self),
4290            Bound::Excluded(_) => panic!("excluded start bound not supported"),
4291            Bound::Unbounded => MultiBufferOffset::ZERO,
4292        };
4293        let end_bound = match range.end_bound() {
4294            Bound::Included(end) => Bound::Included(end.to_offset(self)),
4295            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
4296            Bound::Unbounded => Bound::Unbounded,
4297        };
4298        let bounds = (Bound::Included(start), end_bound);
4299
4300        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4301        cursor.seek(&start);
4302
4303        let mut result: Vec<(
4304            &BufferSnapshot,
4305            Range<BufferOffset>,
4306            ExcerptId,
4307            Range<text::Anchor>,
4308        )> = Vec::new();
4309        while let Some(region) = cursor.region() {
4310            let dominated_by_end_bound = match end_bound {
4311                Bound::Included(end) => region.range.start > end,
4312                Bound::Excluded(end) => region.range.start >= end,
4313                Bound::Unbounded => false,
4314            };
4315            if dominated_by_end_bound {
4316                break;
4317            }
4318            if region.is_main_buffer {
4319                let start_overshoot = start.saturating_sub(region.range.start);
4320                let end_offset = match end_bound {
4321                    Bound::Included(end) | Bound::Excluded(end) => end,
4322                    Bound::Unbounded => region.range.end,
4323                };
4324                let end_overshoot = end_offset.saturating_sub(region.range.start);
4325                let start = region
4326                    .buffer_range
4327                    .end
4328                    .min(region.buffer_range.start + start_overshoot);
4329                let end = region
4330                    .buffer_range
4331                    .end
4332                    .min(region.buffer_range.start + end_overshoot);
4333                let context = region.excerpt.range.context.clone();
4334                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id, _)| {
4335                    *excerpt_id == region.excerpt.id && prev_range.end == start
4336                }) {
4337                    prev.1.end = end;
4338                } else {
4339                    result.push((region.buffer, start..end, region.excerpt.id, context));
4340                }
4341            }
4342            cursor.next();
4343        }
4344
4345        if let Some(excerpt) = cursor.excerpt() {
4346            let dominated_by_prev_excerpt =
4347                result.last().is_some_and(|(_, _, id, _)| *id == excerpt.id);
4348            if !dominated_by_prev_excerpt && excerpt.text_summary.len == 0 {
4349                let excerpt_position = self.len();
4350                if bounds.contains(&excerpt_position) {
4351                    let buffer_offset =
4352                        BufferOffset(excerpt.range.context.start.to_offset(&excerpt.buffer));
4353                    let context = excerpt.range.context.clone();
4354                    result.push((
4355                        &excerpt.buffer,
4356                        buffer_offset..buffer_offset,
4357                        excerpt.id,
4358                        context,
4359                    ));
4360                }
4361            }
4362        }
4363
4364        result
4365    }
4366
4367    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
4368        &self,
4369        range: Range<T>,
4370    ) -> impl Iterator<
4371        Item = (
4372            &BufferSnapshot,
4373            Range<BufferOffset>,
4374            ExcerptId,
4375            Option<Anchor>,
4376        ),
4377    > + '_ {
4378        let start = range.start.to_offset(self);
4379        let end = range.end.to_offset(self);
4380
4381        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4382        cursor.seek(&start);
4383
4384        std::iter::from_fn(move || {
4385            let region = cursor.region()?;
4386            if region.range.start > end {
4387                return None;
4388            }
4389            let start_overshoot = start.saturating_sub(region.range.start);
4390            let end_overshoot = end.saturating_sub(region.range.start);
4391            let start = region
4392                .buffer_range
4393                .end
4394                .min(region.buffer_range.start + start_overshoot);
4395            let end = region
4396                .buffer_range
4397                .end
4398                .min(region.buffer_range.start + end_overshoot);
4399
4400            let region_excerpt_id = region.excerpt.id;
4401            let deleted_hunk_anchor = if region.is_main_buffer {
4402                None
4403            } else {
4404                Some(self.anchor_before(region.range.start))
4405            };
4406            let result = (
4407                region.buffer,
4408                start..end,
4409                region_excerpt_id,
4410                deleted_hunk_anchor,
4411            );
4412            cursor.next();
4413            Some(result)
4414        })
4415    }
4416
4417    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
4418    /// coordinates.
4419    ///
4420    /// The given callback will be called for every excerpt intersecting the given range. It will
4421    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
4422    /// The callback should return an iterator of metadata items from that buffer, each paired
4423    /// with a buffer range.
4424    ///
4425    /// The returned iterator yields each of these metadata items, paired with its range in
4426    /// multi-buffer coordinates.
4427    fn lift_buffer_metadata<'a, MBD, M, I>(
4428        &'a self,
4429        query_range: Range<MBD>,
4430        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<MBD::TextDimension>) -> Option<I>,
4431    ) -> impl Iterator<Item = (Range<MBD>, M, &'a Excerpt)> + 'a
4432    where
4433        I: Iterator<Item = (Range<MBD::TextDimension>, M)> + 'a,
4434        MBD: MultiBufferDimension
4435            + Ord
4436            + Sub<Output = MBD::TextDimension>
4437            + ops::Add<MBD::TextDimension, Output = MBD>
4438            + ops::AddAssign<MBD::TextDimension>,
4439        MBD::TextDimension: Sub<Output = MBD::TextDimension>
4440            + ops::Add<Output = MBD::TextDimension>
4441            + AddAssign<MBD::TextDimension>
4442            + Ord,
4443    {
4444        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4445        let mut cursor = self.cursor::<MBD, MBD::TextDimension>();
4446
4447        // Find the excerpt and buffer offset where the given range ends.
4448        cursor.seek(&query_range.end);
4449        let mut range_end = None;
4450        while let Some(region) = cursor.region() {
4451            if region.is_main_buffer {
4452                let mut buffer_end = region.buffer_range.start;
4453                let overshoot = if query_range.end > region.range.start {
4454                    query_range.end - region.range.start
4455                } else {
4456                    <MBD::TextDimension>::default()
4457                };
4458                buffer_end = buffer_end + overshoot;
4459                range_end = Some((region.excerpt.id, buffer_end));
4460                break;
4461            }
4462            cursor.next();
4463        }
4464
4465        cursor.seek(&query_range.start);
4466
4467        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4468            && region.range.start > MBD::default()
4469        {
4470            cursor.prev()
4471        } else if let Some(region) = cursor.region()
4472            && region.is_main_buffer
4473            && region.diff_hunk_status.is_some()
4474        {
4475            cursor.prev();
4476            if cursor.region().is_none_or(|region| region.is_main_buffer) {
4477                cursor.next();
4478            }
4479        }
4480
4481        iter::from_fn(move || {
4482            loop {
4483                let excerpt = cursor.excerpt()?;
4484
4485                // If we have already retrieved metadata for this excerpt, continue to use it.
4486                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4487                    .as_mut()
4488                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4489                {
4490                    Some(metadata)
4491                }
4492                // Otherwise, compute the intersection of the input range with the excerpt's range,
4493                // and retrieve the metadata for the resulting range.
4494                else {
4495                    let region = cursor.region()?;
4496                    let mut buffer_start;
4497                    if region.is_main_buffer {
4498                        buffer_start = region.buffer_range.start;
4499                        if query_range.start > region.range.start {
4500                            let overshoot = query_range.start - region.range.start;
4501                            buffer_start = buffer_start + overshoot;
4502                        }
4503                        buffer_start = buffer_start.min(region.buffer_range.end);
4504                    } else {
4505                        buffer_start = cursor.main_buffer_position()?;
4506                    };
4507                    let mut buffer_end = excerpt
4508                        .range
4509                        .context
4510                        .end
4511                        .summary::<MBD::TextDimension>(&excerpt.buffer);
4512                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4513                        && excerpt.id == end_excerpt_id
4514                    {
4515                        buffer_end = buffer_end.min(end_buffer_offset);
4516                    }
4517
4518                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4519                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4520                    })
4521                };
4522
4523                // Visit each metadata item.
4524                if let Some((metadata_buffer_range, metadata)) =
4525                    metadata_iter.and_then(Iterator::next)
4526                {
4527                    // Find the multibuffer regions that contain the start and end of
4528                    // the metadata item's range.
4529                    if metadata_buffer_range.start > <MBD::TextDimension>::default() {
4530                        while let Some(region) = cursor.region() {
4531                            if (region.is_main_buffer
4532                                && (region.buffer_range.end >= metadata_buffer_range.start
4533                                    || cursor.is_at_end_of_excerpt()))
4534                                || (!region.is_main_buffer
4535                                    && region.buffer_range.start == metadata_buffer_range.start)
4536                            {
4537                                break;
4538                            }
4539                            cursor.next();
4540                        }
4541                    }
4542                    let start_region = cursor.region()?.clone();
4543                    while let Some(region) = cursor.region() {
4544                        if region.is_main_buffer
4545                            && (region.buffer_range.end > metadata_buffer_range.end
4546                                || cursor.is_at_end_of_excerpt())
4547                        {
4548                            break;
4549                        }
4550                        cursor.next();
4551                    }
4552                    let end_region = cursor.region();
4553
4554                    // Convert the metadata item's range into multibuffer coordinates.
4555                    let mut start_position = start_region.range.start;
4556                    let region_buffer_start = start_region.buffer_range.start;
4557                    if start_region.is_main_buffer
4558                        && metadata_buffer_range.start > region_buffer_start
4559                    {
4560                        start_position =
4561                            start_position + (metadata_buffer_range.start - region_buffer_start);
4562                        start_position = start_position.min(start_region.range.end);
4563                    }
4564
4565                    let mut end_position = self.max_position();
4566                    if let Some(end_region) = &end_region {
4567                        end_position = end_region.range.start;
4568                        debug_assert!(end_region.is_main_buffer);
4569                        let region_buffer_start = end_region.buffer_range.start;
4570                        if metadata_buffer_range.end > region_buffer_start {
4571                            end_position =
4572                                end_position + (metadata_buffer_range.end - region_buffer_start);
4573                        }
4574                        end_position = end_position.min(end_region.range.end);
4575                    }
4576
4577                    if start_position <= query_range.end && end_position >= query_range.start {
4578                        return Some((start_position..end_position, metadata, excerpt));
4579                    }
4580                }
4581                // When there are no more metadata items for this excerpt, move to the next excerpt.
4582                else {
4583                    current_excerpt_metadata.take();
4584                    if let Some((end_excerpt_id, _)) = range_end
4585                        && excerpt.id == end_excerpt_id
4586                    {
4587                        return None;
4588                    }
4589                    cursor.next_excerpt_forwards();
4590                }
4591            }
4592        })
4593    }
4594
4595    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4596        let offset = position.to_offset(self);
4597
4598        let mut cursor = self
4599            .cursor::<DimensionPair<MultiBufferOffset, Point>, DimensionPair<BufferOffset, Point>>(
4600            );
4601        cursor.seek(&DimensionPair {
4602            key: offset,
4603            value: None,
4604        });
4605        cursor.seek_to_start_of_current_excerpt();
4606        let excerpt = cursor.excerpt()?;
4607
4608        let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4609        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4610        let current_position = self
4611            .anchor_before(offset)
4612            .text_anchor
4613            .to_offset(&excerpt.buffer);
4614
4615        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4616            if let Some(main_buffer) = &diff.main_buffer {
4617                for hunk in diff
4618                    .hunks_intersecting_base_text_range_rev(excerpt_start..excerpt_end, main_buffer)
4619                {
4620                    if hunk.diff_base_byte_range.end >= current_position {
4621                        continue;
4622                    }
4623                    let hunk_start = excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start);
4624                    let start = Anchor::in_buffer(excerpt.id, hunk_start).to_point(self);
4625                    return Some(MultiBufferRow(start.row));
4626                }
4627            } else {
4628                let excerpt_end = excerpt
4629                    .buffer
4630                    .anchor_before(excerpt_end.min(current_position));
4631                for hunk in diff.hunks_intersecting_range_rev(
4632                    excerpt.range.context.start..excerpt_end,
4633                    &excerpt.buffer,
4634                ) {
4635                    let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4636                    if hunk_end >= current_position {
4637                        continue;
4638                    }
4639                    let start =
4640                        Anchor::in_buffer(excerpt.id, hunk.buffer_range.start).to_point(self);
4641                    return Some(MultiBufferRow(start.row));
4642                }
4643            }
4644        }
4645
4646        loop {
4647            cursor.prev_excerpt();
4648            let excerpt = cursor.excerpt()?;
4649
4650            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4651                continue;
4652            };
4653            if let Some(main_buffer) = &diff.main_buffer {
4654                let Some(hunk) = diff
4655                    .hunks_intersecting_base_text_range_rev(
4656                        excerpt.range.context.to_offset(&excerpt.buffer),
4657                        main_buffer,
4658                    )
4659                    .next()
4660                else {
4661                    continue;
4662                };
4663                let hunk_start = excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start);
4664                let start = Anchor::in_buffer(excerpt.id, hunk_start).to_point(self);
4665                return Some(MultiBufferRow(start.row));
4666            } else {
4667                let Some(hunk) = diff
4668                    .hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer)
4669                    .next()
4670                else {
4671                    continue;
4672                };
4673                let start = Anchor::in_buffer(excerpt.id, hunk.buffer_range.start).to_point(self);
4674                return Some(MultiBufferRow(start.row));
4675            }
4676        }
4677    }
4678
4679    pub fn has_diff_hunks(&self) -> bool {
4680        self.diffs.values().any(|diff| !diff.is_empty())
4681    }
4682
4683    pub fn is_inside_word<T: ToOffset>(
4684        &self,
4685        position: T,
4686        scope_context: Option<CharScopeContext>,
4687    ) -> bool {
4688        let position = position.to_offset(self);
4689        let classifier = self
4690            .char_classifier_at(position)
4691            .scope_context(scope_context);
4692        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4693        let prev_char_kind = self
4694            .reversed_chars_at(position)
4695            .next()
4696            .map(|c| classifier.kind(c));
4697        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4698    }
4699
4700    pub fn surrounding_word<T: ToOffset>(
4701        &self,
4702        start: T,
4703        scope_context: Option<CharScopeContext>,
4704    ) -> (Range<MultiBufferOffset>, Option<CharKind>) {
4705        let mut start = start.to_offset(self);
4706        let mut end = start;
4707        let mut next_chars = self.chars_at(start).peekable();
4708        let mut prev_chars = self.reversed_chars_at(start).peekable();
4709
4710        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4711
4712        let word_kind = cmp::max(
4713            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4714            next_chars.peek().copied().map(|c| classifier.kind(c)),
4715        );
4716
4717        for ch in prev_chars {
4718            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4719                start -= ch.len_utf8();
4720            } else {
4721                break;
4722            }
4723        }
4724
4725        for ch in next_chars {
4726            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4727                end += ch.len_utf8();
4728            } else {
4729                break;
4730            }
4731        }
4732
4733        (start..end, word_kind)
4734    }
4735
4736    pub fn char_kind_before<T: ToOffset>(
4737        &self,
4738        start: T,
4739        scope_context: Option<CharScopeContext>,
4740    ) -> Option<CharKind> {
4741        let start = start.to_offset(self);
4742        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4743        self.reversed_chars_at(start)
4744            .next()
4745            .map(|ch| classifier.kind(ch))
4746    }
4747
4748    pub fn is_singleton(&self) -> bool {
4749        self.singleton
4750    }
4751
4752    pub fn as_singleton(&self) -> Option<(ExcerptId, BufferId, &BufferSnapshot)> {
4753        if self.singleton {
4754            self.excerpts
4755                .iter()
4756                .next()
4757                .map(|e| (e.id, e.buffer_id, &*e.buffer))
4758        } else {
4759            None
4760        }
4761    }
4762
4763    pub fn len(&self) -> MultiBufferOffset {
4764        self.diff_transforms.summary().output.len
4765    }
4766
4767    pub fn max_position<MBD: MultiBufferDimension>(&self) -> MBD {
4768        MBD::from_summary(&self.text_summary())
4769    }
4770
4771    pub fn is_empty(&self) -> bool {
4772        self.diff_transforms.summary().output.len == MultiBufferOffset(0)
4773    }
4774
4775    pub fn widest_line_number(&self) -> u32 {
4776        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4777        self.excerpts.summary().widest_line_number + 1
4778    }
4779
4780    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4781        let range = range.start.to_offset(self)..range.end.to_offset(self);
4782        let mut excerpts = self.cursor::<MultiBufferOffset, BufferOffset>();
4783        excerpts.seek(&range.start);
4784
4785        let mut chunk;
4786        let mut has_trailing_newline;
4787        let excerpt_bytes;
4788        if let Some(region) = excerpts.region() {
4789            let mut bytes = region.buffer.bytes_in_range(
4790                region.buffer_range.start + (range.start - region.range.start)
4791                    ..(region.buffer_range.start + (range.end - region.range.start))
4792                        .min(region.buffer_range.end),
4793            );
4794            chunk = bytes.next().unwrap_or(&[][..]);
4795            excerpt_bytes = Some(bytes);
4796            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4797            if chunk.is_empty() && has_trailing_newline {
4798                chunk = b"\n";
4799                has_trailing_newline = false;
4800            }
4801        } else {
4802            chunk = &[][..];
4803            excerpt_bytes = None;
4804            has_trailing_newline = false;
4805        };
4806
4807        MultiBufferBytes {
4808            range,
4809            cursor: excerpts,
4810            excerpt_bytes,
4811            has_trailing_newline,
4812            chunk,
4813        }
4814    }
4815
4816    pub fn reversed_bytes_in_range<T: ToOffset>(
4817        &self,
4818        range: Range<T>,
4819    ) -> ReversedMultiBufferBytes<'_> {
4820        let range = range.start.to_offset(self)..range.end.to_offset(self);
4821        let mut chunks = self.reversed_chunks_in_range(range.clone());
4822        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4823        ReversedMultiBufferBytes {
4824            range,
4825            chunks,
4826            chunk,
4827        }
4828    }
4829
4830    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4831        let mut cursor = self.cursor::<Point, Point>();
4832        cursor.seek(&Point::new(start_row.0, 0));
4833        let mut result = MultiBufferRows {
4834            point: Point::new(0, 0),
4835            is_empty: self.excerpts.is_empty(),
4836            is_singleton: self.is_singleton(),
4837            cursor,
4838        };
4839        result.seek(start_row);
4840        result
4841    }
4842
4843    pub fn chunks<T: ToOffset>(
4844        &self,
4845        range: Range<T>,
4846        language_aware: bool,
4847    ) -> MultiBufferChunks<'_> {
4848        let mut chunks = MultiBufferChunks {
4849            excerpt_offset_range: ExcerptDimension(MultiBufferOffset::ZERO)
4850                ..ExcerptDimension(MultiBufferOffset::ZERO),
4851            range: MultiBufferOffset::ZERO..MultiBufferOffset::ZERO,
4852            excerpts: self.excerpts.cursor(()),
4853            diff_transforms: self.diff_transforms.cursor(()),
4854            diffs: &self.diffs,
4855            diff_base_chunks: None,
4856            excerpt_chunks: None,
4857            buffer_chunk: None,
4858            language_aware,
4859        };
4860        let range = range.start.to_offset(self)..range.end.to_offset(self);
4861        chunks.seek(range);
4862        chunks
4863    }
4864
4865    pub fn clip_offset(&self, offset: MultiBufferOffset, bias: Bias) -> MultiBufferOffset {
4866        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4867    }
4868
4869    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4870        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4871    }
4872
4873    pub fn clip_offset_utf16(
4874        &self,
4875        offset: MultiBufferOffsetUtf16,
4876        bias: Bias,
4877    ) -> MultiBufferOffsetUtf16 {
4878        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4879    }
4880
4881    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4882        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4883            buffer.clip_point_utf16(Unclipped(point), bias)
4884        })
4885    }
4886
4887    pub fn offset_to_point(&self, offset: MultiBufferOffset) -> Point {
4888        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4889    }
4890
4891    pub fn offset_to_point_utf16(&self, offset: MultiBufferOffset) -> PointUtf16 {
4892        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4893    }
4894
4895    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4896        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4897    }
4898
4899    pub fn point_utf16_to_point(&self, point: PointUtf16) -> Point {
4900        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_point)
4901    }
4902
4903    #[instrument(skip_all)]
4904    pub fn point_to_offset(&self, point: Point) -> MultiBufferOffset {
4905        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4906    }
4907
4908    pub fn point_to_offset_utf16(&self, point: Point) -> MultiBufferOffsetUtf16 {
4909        self.convert_dimension(point, text::BufferSnapshot::point_to_offset_utf16)
4910    }
4911
4912    pub fn offset_utf16_to_offset(&self, offset: MultiBufferOffsetUtf16) -> MultiBufferOffset {
4913        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4914    }
4915
4916    pub fn offset_to_offset_utf16(&self, offset: MultiBufferOffset) -> MultiBufferOffsetUtf16 {
4917        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4918    }
4919
4920    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> MultiBufferOffset {
4921        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4922    }
4923
4924    pub fn point_utf16_to_offset_utf16(&self, point: PointUtf16) -> MultiBufferOffsetUtf16 {
4925        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset_utf16)
4926    }
4927
4928    fn clip_dimension<MBD, BD>(
4929        &self,
4930        position: MBD,
4931        bias: Bias,
4932        clip_buffer_position: fn(&text::BufferSnapshot, BD, Bias) -> BD,
4933    ) -> MBD
4934    where
4935        MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
4936        BD: TextDimension + Sub<Output = <MBD as Sub>::Output> + AddAssign<<MBD as Sub>::Output>,
4937    {
4938        let mut cursor = self.cursor::<MBD, BD>();
4939        cursor.seek(&position);
4940        if let Some(region) = cursor.region() {
4941            if position >= region.range.end {
4942                return region.range.end;
4943            }
4944            let overshoot = position - region.range.start;
4945            let mut buffer_position = region.buffer_range.start;
4946            buffer_position += overshoot;
4947            let clipped_buffer_position =
4948                clip_buffer_position(region.buffer, buffer_position, bias);
4949            let mut position = region.range.start;
4950            position += clipped_buffer_position - region.buffer_range.start;
4951            position
4952        } else {
4953            self.max_position()
4954        }
4955    }
4956
4957    #[instrument(skip_all)]
4958    fn convert_dimension<MBR1, MBR2, BR1, BR2>(
4959        &self,
4960        key: MBR1,
4961        convert_buffer_dimension: fn(&text::BufferSnapshot, BR1) -> BR2,
4962    ) -> MBR2
4963    where
4964        MBR1: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBR1 as Sub>::Output>,
4965        BR1: TextDimension + Sub<Output = <MBR1 as Sub>::Output> + AddAssign<<MBR1 as Sub>::Output>,
4966        MBR2: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBR2 as Sub>::Output>,
4967        BR2: TextDimension + Sub<Output = <MBR2 as Sub>::Output> + AddAssign<<MBR2 as Sub>::Output>,
4968    {
4969        let mut cursor = self.cursor::<DimensionPair<MBR1, MBR2>, DimensionPair<BR1, BR2>>();
4970        cursor.seek(&DimensionPair { key, value: None });
4971        if let Some(region) = cursor.region() {
4972            if key >= region.range.end.key {
4973                return region.range.end.value.unwrap();
4974            }
4975            let start_key = region.range.start.key;
4976            let start_value = region.range.start.value.unwrap();
4977            let buffer_start_key = region.buffer_range.start.key;
4978            let buffer_start_value = region.buffer_range.start.value.unwrap();
4979            let mut buffer_key = buffer_start_key;
4980            buffer_key += key - start_key;
4981            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4982            let mut result = start_value;
4983            result += buffer_value - buffer_start_value;
4984            result
4985        } else {
4986            self.max_position()
4987        }
4988    }
4989
4990    pub fn point_to_buffer_offset<T: ToOffset>(
4991        &self,
4992        point: T,
4993    ) -> Option<(&BufferSnapshot, BufferOffset)> {
4994        let offset = point.to_offset(self);
4995        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4996        cursor.seek(&offset);
4997        let region = cursor.region()?;
4998        let overshoot = offset - region.range.start;
4999        let buffer_offset = region.buffer_range.start + overshoot;
5000        if buffer_offset == BufferOffset(region.buffer.len() + 1)
5001            && region.has_trailing_newline
5002            && !region.is_main_buffer
5003        {
5004            let main_buffer_position = cursor.main_buffer_position()?;
5005            let buffer_snapshot = &cursor.excerpt()?.buffer;
5006            return Some((buffer_snapshot, main_buffer_position));
5007        } else if buffer_offset > BufferOffset(region.buffer.len()) {
5008            return None;
5009        }
5010        Some((region.buffer, buffer_offset))
5011    }
5012
5013    pub fn point_to_buffer_point(
5014        &self,
5015        point: Point,
5016    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
5017        let mut cursor = self.cursor::<Point, Point>();
5018        cursor.seek(&point);
5019        let region = cursor.region()?;
5020        let overshoot = point - region.range.start;
5021        let buffer_point = region.buffer_range.start + overshoot;
5022        let excerpt = cursor.excerpt()?;
5023        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
5024            && region.has_trailing_newline
5025            && !region.is_main_buffer
5026        {
5027            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
5028        } else if buffer_point > region.buffer.max_point() {
5029            return None;
5030        }
5031        Some((region.buffer, buffer_point, excerpt.id))
5032    }
5033
5034    pub fn suggested_indents(
5035        &self,
5036        rows: impl IntoIterator<Item = u32>,
5037        cx: &App,
5038    ) -> BTreeMap<MultiBufferRow, IndentSize> {
5039        let mut result = BTreeMap::new();
5040        self.suggested_indents_callback(
5041            rows,
5042            &mut |row, indent| {
5043                result.insert(row, indent);
5044                ControlFlow::Continue(())
5045            },
5046            cx,
5047        );
5048        result
5049    }
5050
5051    // move this to be a generator once those are a thing
5052    pub fn suggested_indents_callback(
5053        &self,
5054        rows: impl IntoIterator<Item = u32>,
5055        cb: &mut dyn FnMut(MultiBufferRow, IndentSize) -> ControlFlow<()>,
5056        cx: &App,
5057    ) {
5058        let mut rows_for_excerpt = Vec::new();
5059        let mut cursor = self.cursor::<Point, Point>();
5060        let mut rows = rows.into_iter().peekable();
5061        let mut prev_row = u32::MAX;
5062        let mut prev_language_indent_size = IndentSize::default();
5063
5064        while let Some(row) = rows.next() {
5065            cursor.seek(&Point::new(row, 0));
5066            let Some(region) = cursor.region() else {
5067                continue;
5068            };
5069
5070            // Retrieve the language and indent size once for each disjoint region being indented.
5071            let single_indent_size = if row.saturating_sub(1) == prev_row {
5072                prev_language_indent_size
5073            } else {
5074                region
5075                    .buffer
5076                    .language_indent_size_at(Point::new(row, 0), cx)
5077            };
5078            prev_language_indent_size = single_indent_size;
5079            prev_row = row;
5080
5081            let start_buffer_row = region.buffer_range.start.row;
5082            let start_multibuffer_row = region.range.start.row;
5083            let end_multibuffer_row = region.range.end.row;
5084
5085            rows_for_excerpt.push(row);
5086            while let Some(next_row) = rows.peek().copied() {
5087                if end_multibuffer_row > next_row {
5088                    rows_for_excerpt.push(next_row);
5089                    rows.next();
5090                } else {
5091                    break;
5092                }
5093            }
5094
5095            let buffer_rows = rows_for_excerpt
5096                .drain(..)
5097                .map(|row| start_buffer_row + row - start_multibuffer_row);
5098            let buffer_indents = region
5099                .buffer
5100                .suggested_indents(buffer_rows, single_indent_size);
5101            for (row, indent) in buffer_indents {
5102                if cb(
5103                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
5104                    indent,
5105                )
5106                .is_break()
5107                {
5108                    return;
5109                }
5110            }
5111        }
5112    }
5113
5114    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
5115        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
5116            let mut size = buffer.indent_size_for_line(range.start.row);
5117            size.len = size
5118                .len
5119                .min(range.end.column)
5120                .saturating_sub(range.start.column);
5121            size
5122        } else {
5123            IndentSize::spaces(0)
5124        }
5125    }
5126
5127    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
5128        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
5129            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
5130        } else {
5131            LineIndent::spaces(0)
5132        }
5133    }
5134
5135    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
5136        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
5137
5138        if self.language_settings(cx).extend_comment_on_newline
5139            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
5140        {
5141            let delimiters = language_scope.line_comment_prefixes();
5142            for delimiter in delimiters {
5143                if *self
5144                    .chars_at(Point::new(row.0, indent.len() as u32))
5145                    .take(delimiter.chars().count())
5146                    .collect::<String>()
5147                    .as_str()
5148                    == **delimiter
5149                {
5150                    indent.push_str(delimiter);
5151                    break;
5152                }
5153            }
5154        }
5155
5156        indent
5157    }
5158
5159    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
5160    where
5161        T: ToOffset,
5162    {
5163        for char in self.reversed_chars_at(position) {
5164            if !char.is_whitespace() {
5165                return false;
5166            }
5167            if char == '\n' {
5168                return true;
5169            }
5170        }
5171        true
5172    }
5173
5174    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
5175        while row.0 > 0 {
5176            row.0 -= 1;
5177            if !self.is_line_blank(row) {
5178                return Some(row);
5179            }
5180        }
5181        None
5182    }
5183
5184    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
5185        if let Some((_, range)) = self.buffer_line_for_row(row) {
5186            range.end.column - range.start.column
5187        } else {
5188            0
5189        }
5190    }
5191
5192    pub fn line_len_utf16(&self, row: MultiBufferRow) -> u32 {
5193        self.clip_point_utf16(Unclipped(PointUtf16::new(row.0, u32::MAX)), Bias::Left)
5194            .column
5195    }
5196
5197    pub fn buffer_line_for_row(
5198        &self,
5199        row: MultiBufferRow,
5200    ) -> Option<(&BufferSnapshot, Range<Point>)> {
5201        let mut cursor = self.cursor::<Point, Point>();
5202        let point = Point::new(row.0, 0);
5203        cursor.seek(&point);
5204        let region = cursor.region()?;
5205        let overshoot = point.min(region.range.end) - region.range.start;
5206        let buffer_point = region.buffer_range.start + overshoot;
5207        if buffer_point.row > region.buffer_range.end.row {
5208            return None;
5209        }
5210        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
5211        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
5212            .min(region.buffer_range.end);
5213        Some((region.buffer, line_start..line_end))
5214    }
5215
5216    pub fn max_point(&self) -> Point {
5217        self.text_summary().lines
5218    }
5219
5220    pub fn max_row(&self) -> MultiBufferRow {
5221        MultiBufferRow(self.text_summary().lines.row)
5222    }
5223
5224    pub fn text_summary(&self) -> MBTextSummary {
5225        self.diff_transforms.summary().output
5226    }
5227
5228    pub fn text_summary_for_range<MBD, O>(&self, range: Range<O>) -> MBD
5229    where
5230        MBD: MultiBufferDimension + AddAssign,
5231        O: ToOffset,
5232    {
5233        let range = range.start.to_offset(self)..range.end.to_offset(self);
5234        let mut cursor = self
5235            .diff_transforms
5236            .cursor::<Dimensions<MultiBufferOffset, ExcerptOffset>>(());
5237        cursor.seek(&range.start, Bias::Right);
5238
5239        let Some(first_transform) = cursor.item() else {
5240            return MBD::from_summary(&MBTextSummary::default());
5241        };
5242
5243        let diff_transform_start = cursor.start().0;
5244        let diff_transform_end = cursor.end().0;
5245        let diff_start = range.start;
5246        let start_overshoot = diff_start - diff_transform_start;
5247        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
5248
5249        let mut result = match first_transform {
5250            DiffTransform::BufferContent { .. } => {
5251                let excerpt_start = cursor.start().1 + start_overshoot;
5252                let excerpt_end = cursor.start().1 + end_overshoot;
5253                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
5254            }
5255            DiffTransform::DeletedHunk {
5256                buffer_id,
5257                base_text_byte_range,
5258                has_trailing_newline,
5259                ..
5260            } => {
5261                let buffer_start = base_text_byte_range.start + start_overshoot;
5262                let mut buffer_end = base_text_byte_range.start + end_overshoot;
5263                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
5264                    panic!("{:?} is in non-existent deleted hunk", range.start)
5265                };
5266
5267                let include_trailing_newline =
5268                    *has_trailing_newline && range.end >= diff_transform_end;
5269                if include_trailing_newline {
5270                    buffer_end -= 1;
5271                }
5272
5273                let mut summary = base_text
5274                    .text_summary_for_range::<MBD::TextDimension, _>(buffer_start..buffer_end);
5275
5276                if include_trailing_newline {
5277                    summary.add_assign(&<MBD::TextDimension>::from_text_summary(
5278                        &TextSummary::newline(),
5279                    ))
5280                }
5281
5282                let mut result = MBD::default();
5283                result.add_text_dim(&summary);
5284                result
5285            }
5286        };
5287        if range.end < diff_transform_end {
5288            return result;
5289        }
5290
5291        cursor.next();
5292        result.add_mb_text_summary(
5293            &cursor
5294                .summary::<_, OutputDimension<_>>(&range.end, Bias::Right)
5295                .0,
5296        );
5297
5298        let Some(last_transform) = cursor.item() else {
5299            return result;
5300        };
5301
5302        let overshoot = range.end - cursor.start().0;
5303        let suffix = match last_transform {
5304            DiffTransform::BufferContent { .. } => {
5305                let end = cursor.start().1 + overshoot;
5306                self.text_summary_for_excerpt_offset_range::<MBD>(cursor.start().1..end)
5307            }
5308            DiffTransform::DeletedHunk {
5309                base_text_byte_range,
5310                buffer_id,
5311                has_trailing_newline,
5312                ..
5313            } => {
5314                let buffer_end = base_text_byte_range.start + overshoot;
5315                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
5316                    panic!("{:?} is in non-existent deleted hunk", range.end)
5317                };
5318
5319                let mut suffix = base_text.text_summary_for_range::<MBD::TextDimension, _>(
5320                    base_text_byte_range.start..buffer_end,
5321                );
5322                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
5323                    suffix.add_assign(&<MBD::TextDimension>::from_text_summary(
5324                        &TextSummary::from("\n"),
5325                    ))
5326                }
5327
5328                let mut result = MBD::default();
5329                result.add_text_dim(&suffix);
5330                result
5331            }
5332        };
5333
5334        result += suffix;
5335        result
5336    }
5337
5338    fn text_summary_for_excerpt_offset_range<MBD>(&self, mut range: Range<ExcerptOffset>) -> MBD
5339    where
5340        MBD: MultiBufferDimension + AddAssign,
5341    {
5342        let mut summary = MBD::default();
5343        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
5344        cursor.seek(&range.start, Bias::Right);
5345        if let Some(excerpt) = cursor.item() {
5346            let mut end_before_newline = cursor.end();
5347            if excerpt.has_trailing_newline {
5348                end_before_newline -= 1;
5349            }
5350
5351            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5352            let start_in_excerpt = excerpt_start + (range.start - *cursor.start());
5353            let end_in_excerpt =
5354                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start());
5355            summary.add_text_dim(
5356                &excerpt
5357                    .buffer
5358                    .text_summary_for_range::<MBD::TextDimension, _>(
5359                        start_in_excerpt..end_in_excerpt,
5360                    ),
5361            );
5362
5363            if range.end > end_before_newline {
5364                summary.add_mb_text_summary(&MBTextSummary::from(TextSummary::newline()));
5365            }
5366
5367            cursor.next();
5368        }
5369
5370        if range.end > *cursor.start() {
5371            summary += cursor
5372                .summary::<_, ExcerptDimension<MBD>>(&range.end, Bias::Right)
5373                .0;
5374            if let Some(excerpt) = cursor.item() {
5375                range.end = cmp::max(*cursor.start(), range.end);
5376
5377                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5378                let end_in_excerpt = excerpt_start + (range.end - *cursor.start());
5379                summary.add_text_dim(
5380                    &excerpt
5381                        .buffer
5382                        .text_summary_for_range::<MBD::TextDimension, _>(
5383                            excerpt_start..end_in_excerpt,
5384                        ),
5385                );
5386            }
5387        }
5388
5389        summary
5390    }
5391
5392    pub fn summary_for_anchor<MBD>(&self, anchor: &Anchor) -> MBD
5393    where
5394        MBD: MultiBufferDimension
5395            + Ord
5396            + Sub<Output = MBD::TextDimension>
5397            + Sub<MBD::TextDimension, Output = MBD>
5398            + AddAssign<MBD::TextDimension>
5399            + Add<MBD::TextDimension, Output = MBD>,
5400        MBD::TextDimension: Sub<Output = MBD::TextDimension> + Ord,
5401    {
5402        let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
5403        let locator = self.excerpt_locator_for_id(excerpt_id);
5404        let (start, _, mut item) = self
5405            .excerpts
5406            .find::<ExcerptSummary, _>((), locator, Bias::Left);
5407        let mut start = MBD::from_summary(&start.text);
5408        if item.is_none() && excerpt_id == ExcerptId::max() {
5409            item = self.excerpts.last();
5410            if let Some(last_summary) = self.excerpts.last_summary() {
5411                start = start - <MBD::TextDimension>::from_text_summary(&last_summary.text.into());
5412            }
5413        }
5414
5415        let excerpt_start_position = ExcerptDimension(start);
5416        if self.diff_transforms.is_empty() {
5417            if let Some(excerpt) = item {
5418                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5419                    return excerpt_start_position.0;
5420                }
5421                let excerpt_buffer_start = excerpt
5422                    .range
5423                    .context
5424                    .start
5425                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5426                let excerpt_buffer_end = excerpt
5427                    .range
5428                    .context
5429                    .end
5430                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5431                let buffer_summary = anchor
5432                    .text_anchor
5433                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5434                let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5435                let mut position = excerpt_start_position;
5436                if summary > excerpt_buffer_start {
5437                    position += summary - excerpt_buffer_start;
5438                }
5439
5440                position.0
5441            } else {
5442                excerpt_start_position.0
5443            }
5444        } else {
5445            let mut diff_transforms_cursor = self
5446                .diff_transforms
5447                .cursor::<Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>>(());
5448            diff_transforms_cursor.next();
5449
5450            if let Some(excerpt) = item {
5451                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5452                    return self.resolve_summary_for_min_or_max_anchor(
5453                        &Anchor::min(),
5454                        excerpt_start_position,
5455                        &mut diff_transforms_cursor,
5456                    );
5457                }
5458                let excerpt_buffer_start = excerpt
5459                    .range
5460                    .context
5461                    .start
5462                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5463                let excerpt_buffer_end = excerpt
5464                    .range
5465                    .context
5466                    .end
5467                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5468                let buffer_summary = anchor
5469                    .text_anchor
5470                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5471                let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5472                let mut position = excerpt_start_position;
5473                if summary > excerpt_buffer_start {
5474                    position += summary - excerpt_buffer_start;
5475                }
5476
5477                if diff_transforms_cursor.start().0 < position {
5478                    diff_transforms_cursor.seek_forward(&position, Bias::Left);
5479                }
5480                self.resolve_summary_for_anchor(
5481                    &anchor,
5482                    position,
5483                    &mut diff_transforms_cursor,
5484                    &excerpt.buffer,
5485                )
5486            } else {
5487                diff_transforms_cursor.seek_forward(&excerpt_start_position, Bias::Left);
5488                self.resolve_summary_for_min_or_max_anchor(
5489                    &Anchor::max(),
5490                    excerpt_start_position,
5491                    &mut diff_transforms_cursor,
5492                )
5493            }
5494        }
5495    }
5496
5497    /// Maps an anchor's excerpt-space position to its output-space position by
5498    /// walking the diff transforms. The cursor is shared across consecutive
5499    /// calls, so it may already be partway through the transform list.
5500    fn resolve_summary_for_anchor<MBD>(
5501        &self,
5502        anchor: &Anchor,
5503        excerpt_position: ExcerptDimension<MBD>,
5504        diff_transforms: &mut Cursor<
5505            DiffTransform,
5506            Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>,
5507        >,
5508        excerpt_buffer: &text::BufferSnapshot,
5509    ) -> MBD
5510    where
5511        MBD: MultiBufferDimension + Ord + Sub + AddAssign<<MBD as Sub>::Output>,
5512    {
5513        loop {
5514            let transform_end_position = diff_transforms.end().0;
5515            let item = diff_transforms.item();
5516            let at_transform_end = transform_end_position == excerpt_position && item.is_some();
5517
5518            // A right-biased anchor at a transform boundary belongs to the
5519            // *next* transform, so advance past the current one.
5520            if anchor.text_anchor.bias == Bias::Right && at_transform_end {
5521                diff_transforms.next();
5522                continue;
5523            }
5524
5525            let mut position = diff_transforms.start().1;
5526            match item {
5527                Some(DiffTransform::DeletedHunk {
5528                    buffer_id,
5529                    base_text_byte_range,
5530                    hunk_info,
5531                    ..
5532                }) => {
5533                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
5534                        && let Some(base_text) =
5535                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
5536                        && diff_base_anchor.is_valid(&base_text)
5537                    {
5538                        // The anchor carries a diff-base position — resolve it
5539                        // to a location inside the deleted hunk.
5540                        let base_text_offset = diff_base_anchor.to_offset(base_text);
5541                        if base_text_offset >= base_text_byte_range.start
5542                            && base_text_offset <= base_text_byte_range.end
5543                        {
5544                            let position_in_hunk = base_text
5545                                .text_summary_for_range::<MBD::TextDimension, _>(
5546                                    base_text_byte_range.start..base_text_offset,
5547                                );
5548                            position.0.add_text_dim(&position_in_hunk);
5549                        } else if at_transform_end {
5550                            // diff_base offset falls outside this hunk's range;
5551                            // advance to see if the next transform is a better fit.
5552                            diff_transforms.next();
5553                            continue;
5554                        }
5555                    } else if at_transform_end
5556                        && anchor
5557                            .text_anchor
5558                            .cmp(&hunk_info.hunk_start_anchor, excerpt_buffer)
5559                            .is_gt()
5560                    {
5561                        // The anchor has no (valid) diff-base position, so it
5562                        // belongs in the buffer content, not in the deleted
5563                        // hunk. However, after an edit deletes the text between
5564                        // the hunk boundary and this anchor, both resolve to
5565                        // the same excerpt_position—landing us here on the
5566                        // DeletedHunk left behind by the shared cursor. Use the
5567                        // CRDT ordering to detect that the anchor is strictly
5568                        // *past* the hunk boundary and skip to the following
5569                        // BufferContent.
5570                        diff_transforms.next();
5571                        continue;
5572                    }
5573                }
5574                _ => {
5575                    // On a BufferContent (or no transform). If the anchor
5576                    // carries a diff_base_anchor it needs a DeletedHunk, so
5577                    // advance to find one.
5578                    if at_transform_end && anchor.diff_base_anchor.is_some() {
5579                        diff_transforms.next();
5580                        continue;
5581                    }
5582                    let overshoot = excerpt_position - diff_transforms.start().0;
5583                    position += overshoot;
5584                }
5585            }
5586
5587            return position.0;
5588        }
5589    }
5590
5591    /// Like `resolve_summary_for_anchor` but optimized for min/max anchors.
5592    fn resolve_summary_for_min_or_max_anchor<MBD>(
5593        &self,
5594        anchor: &Anchor,
5595        excerpt_position: ExcerptDimension<MBD>,
5596        diff_transforms: &mut Cursor<
5597            DiffTransform,
5598            Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>,
5599        >,
5600    ) -> MBD
5601    where
5602        MBD: MultiBufferDimension + Ord + Sub + AddAssign<<MBD as Sub>::Output>,
5603    {
5604        loop {
5605            let transform_end_position = diff_transforms.end().0;
5606            let item = diff_transforms.item();
5607            let at_transform_end = transform_end_position == excerpt_position && item.is_some();
5608
5609            // A right-biased anchor at a transform boundary belongs to the
5610            // *next* transform, so advance past the current one.
5611            if anchor.text_anchor.bias == Bias::Right && at_transform_end {
5612                diff_transforms.next();
5613                continue;
5614            }
5615
5616            let mut position = diff_transforms.start().1;
5617            if let Some(DiffTransform::BufferContent { .. }) | None = item {
5618                let overshoot = excerpt_position - diff_transforms.start().0;
5619                position += overshoot;
5620            }
5621
5622            return position.0;
5623        }
5624    }
5625
5626    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
5627        let mut cursor = self
5628            .excerpts
5629            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
5630        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
5631
5632        cursor.seek(&Some(locator), Bias::Left);
5633        if cursor.item().is_none() && anchor.excerpt_id == ExcerptId::max() {
5634            cursor.prev();
5635        }
5636
5637        let mut position = cursor.start().1;
5638        if let Some(excerpt) = cursor.item()
5639            && (excerpt.id == anchor.excerpt_id || anchor.excerpt_id == ExcerptId::max())
5640        {
5641            let excerpt_buffer_start = excerpt
5642                .buffer
5643                .offset_for_anchor(&excerpt.range.context.start);
5644            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
5645            let buffer_position = cmp::min(
5646                excerpt_buffer_end,
5647                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
5648            );
5649            if buffer_position > excerpt_buffer_start {
5650                position += buffer_position - excerpt_buffer_start;
5651            }
5652        }
5653        position
5654    }
5655
5656    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
5657        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
5658            excerpt_id = *replacement;
5659        }
5660        excerpt_id
5661    }
5662
5663    pub fn summaries_for_anchors<'a, MBD, I>(&'a self, anchors: I) -> Vec<MBD>
5664    where
5665        MBD: MultiBufferDimension
5666            + Ord
5667            + Sub<Output = MBD::TextDimension>
5668            + AddAssign<MBD::TextDimension>,
5669        MBD::TextDimension: Sub<Output = MBD::TextDimension> + Ord,
5670        I: 'a + IntoIterator<Item = &'a Anchor>,
5671    {
5672        let mut anchors = anchors.into_iter().peekable();
5673        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
5674        let mut diff_transforms_cursor = self
5675            .diff_transforms
5676            .cursor::<Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>>(());
5677        diff_transforms_cursor.next();
5678
5679        let mut summaries = Vec::new();
5680        while let Some(anchor) = anchors.peek() {
5681            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
5682
5683            let excerpt_anchors = anchors.peeking_take_while(|anchor| {
5684                self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id
5685            });
5686
5687            let locator = self.excerpt_locator_for_id(excerpt_id);
5688            cursor.seek_forward(locator, Bias::Left);
5689            if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
5690                cursor.prev();
5691            }
5692
5693            let excerpt_start_position = ExcerptDimension(MBD::from_summary(&cursor.start().text));
5694            if let Some(excerpt) = cursor.item() {
5695                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5696                    let position = self.resolve_summary_for_min_or_max_anchor(
5697                        &Anchor::min(),
5698                        excerpt_start_position,
5699                        &mut diff_transforms_cursor,
5700                    );
5701                    summaries.extend(excerpt_anchors.map(|_| position));
5702                    continue;
5703                }
5704                let excerpt_buffer_start = excerpt
5705                    .range
5706                    .context
5707                    .start
5708                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5709                let excerpt_buffer_end = excerpt
5710                    .range
5711                    .context
5712                    .end
5713                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5714                for (buffer_summary, anchor) in excerpt
5715                    .buffer
5716                    .summaries_for_anchors_with_payload::<MBD::TextDimension, _, _>(
5717                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
5718                    )
5719                {
5720                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5721                    let mut position = excerpt_start_position;
5722                    if summary > excerpt_buffer_start {
5723                        position += summary - excerpt_buffer_start;
5724                    }
5725
5726                    if diff_transforms_cursor.start().0 < position {
5727                        diff_transforms_cursor.seek_forward(&position, Bias::Left);
5728                    }
5729
5730                    summaries.push(self.resolve_summary_for_anchor(
5731                        anchor,
5732                        position,
5733                        &mut diff_transforms_cursor,
5734                        &excerpt.buffer,
5735                    ));
5736                }
5737            } else {
5738                diff_transforms_cursor.seek_forward(&excerpt_start_position, Bias::Left);
5739                let position = self.resolve_summary_for_min_or_max_anchor(
5740                    &Anchor::max(),
5741                    excerpt_start_position,
5742                    &mut diff_transforms_cursor,
5743                );
5744                summaries.extend(excerpt_anchors.map(|_| position));
5745            }
5746        }
5747
5748        summaries
5749    }
5750
5751    pub fn dimensions_from_points<'a, MBD>(
5752        &'a self,
5753        points: impl 'a + IntoIterator<Item = Point>,
5754    ) -> impl 'a + Iterator<Item = MBD>
5755    where
5756        MBD: MultiBufferDimension + Sub + AddAssign<<MBD as Sub>::Output>,
5757    {
5758        let mut cursor = self.cursor::<DimensionPair<Point, MBD>, Point>();
5759        cursor.seek(&DimensionPair {
5760            key: Point::default(),
5761            value: None,
5762        });
5763        let mut points = points.into_iter();
5764        iter::from_fn(move || {
5765            let point = points.next()?;
5766
5767            cursor.seek_forward(&DimensionPair {
5768                key: point,
5769                value: None,
5770            });
5771
5772            if let Some(region) = cursor.region() {
5773                let overshoot = point - region.range.start.key;
5774                let buffer_point = region.buffer_range.start + overshoot;
5775                let mut position = region.range.start.value.unwrap();
5776                position.add_text_dim(
5777                    &region
5778                        .buffer
5779                        .text_summary_for_range(region.buffer_range.start..buffer_point),
5780                );
5781                if point == region.range.end.key && region.has_trailing_newline {
5782                    position.add_mb_text_summary(&MBTextSummary::from(TextSummary::newline()));
5783                }
5784                Some(position)
5785            } else {
5786                Some(MBD::from_summary(&self.text_summary()))
5787            }
5788        })
5789    }
5790
5791    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5792    where
5793        I: 'a + IntoIterator<Item = &'a Anchor>,
5794    {
5795        let mut anchors = anchors.into_iter().enumerate().peekable();
5796        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5797        cursor.next();
5798
5799        let mut result = Vec::new();
5800
5801        while let Some((_, anchor)) = anchors.peek() {
5802            let old_excerpt_id = anchor.excerpt_id;
5803
5804            // Find the location where this anchor's excerpt should be.
5805            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5806            cursor.seek_forward(&Some(old_locator), Bias::Left);
5807
5808            let next_excerpt = cursor.item();
5809            let prev_excerpt = cursor.prev_item();
5810
5811            // Process all of the anchors for this excerpt.
5812            while let Some((anchor_ix, &anchor)) =
5813                anchors.next_if(|(_, anchor)| anchor.excerpt_id == old_excerpt_id)
5814            {
5815                let mut anchor = anchor;
5816
5817                // Leave min and max anchors unchanged if invalid or
5818                // if the old excerpt still exists at this location
5819                let mut kept_position = next_excerpt
5820                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5821                    || old_excerpt_id == ExcerptId::max()
5822                    || old_excerpt_id == ExcerptId::min();
5823
5824                // If the old excerpt no longer exists at this location, then attempt to
5825                // find an equivalent position for this anchor in an adjacent excerpt.
5826                if !kept_position {
5827                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5828                        if excerpt.contains(&anchor) {
5829                            anchor.excerpt_id = excerpt.id;
5830                            kept_position = true;
5831                            break;
5832                        }
5833                    }
5834                }
5835
5836                // If there's no adjacent excerpt that contains the anchor's position,
5837                // then report that the anchor has lost its position.
5838                if !kept_position {
5839                    anchor = if let Some(excerpt) = next_excerpt {
5840                        let mut text_anchor = excerpt
5841                            .range
5842                            .context
5843                            .start
5844                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5845                        if text_anchor
5846                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5847                            .is_gt()
5848                        {
5849                            text_anchor = excerpt.range.context.end;
5850                        }
5851                        Anchor::in_buffer(excerpt.id, text_anchor)
5852                    } else if let Some(excerpt) = prev_excerpt {
5853                        let mut text_anchor = excerpt
5854                            .range
5855                            .context
5856                            .end
5857                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5858                        if text_anchor
5859                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5860                            .is_lt()
5861                        {
5862                            text_anchor = excerpt.range.context.start;
5863                        }
5864                        Anchor::in_buffer(excerpt.id, text_anchor)
5865                    } else if anchor.text_anchor.bias == Bias::Left {
5866                        Anchor::min()
5867                    } else {
5868                        Anchor::max()
5869                    };
5870                }
5871
5872                result.push((anchor_ix, anchor, kept_position));
5873            }
5874        }
5875        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5876        result
5877    }
5878
5879    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5880        self.anchor_at(position, Bias::Left)
5881    }
5882
5883    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5884        self.anchor_at(position, Bias::Right)
5885    }
5886
5887    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5888        let offset = position.to_offset(self);
5889
5890        // Find the given position in the diff transforms. Determine the corresponding
5891        // offset in the excerpts, and whether the position is within a deleted hunk.
5892        let mut diff_transforms = self
5893            .diff_transforms
5894            .cursor::<Dimensions<MultiBufferOffset, ExcerptOffset>>(());
5895        diff_transforms.seek(&offset, Bias::Right);
5896
5897        if offset == diff_transforms.start().0
5898            && bias == Bias::Left
5899            && let Some(prev_item) = diff_transforms.prev_item()
5900            && let DiffTransform::DeletedHunk { .. } = prev_item
5901        {
5902            diff_transforms.prev();
5903        }
5904        let offset_in_transform = offset - diff_transforms.start().0;
5905        let mut excerpt_offset = diff_transforms.start().1;
5906        let mut diff_base_anchor = None;
5907        if let Some(DiffTransform::DeletedHunk {
5908            buffer_id,
5909            base_text_byte_range,
5910            has_trailing_newline,
5911            ..
5912        }) = diff_transforms.item()
5913        {
5914            let diff = self.diffs.get(buffer_id).expect("missing diff");
5915            if offset_in_transform > base_text_byte_range.len() {
5916                debug_assert!(*has_trailing_newline);
5917                bias = Bias::Right;
5918            } else {
5919                diff_base_anchor = Some(
5920                    diff.base_text()
5921                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5922                );
5923                bias = Bias::Left;
5924            }
5925        } else {
5926            excerpt_offset += MultiBufferOffset(offset_in_transform);
5927        };
5928
5929        let mut excerpts = self
5930            .excerpts
5931            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5932        excerpts.seek(&excerpt_offset, Bias::Right);
5933        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5934            excerpts.prev();
5935        }
5936        if let Some(excerpt) = excerpts.item() {
5937            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0);
5938            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5939                overshoot -= 1;
5940                bias = Bias::Right;
5941            }
5942
5943            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5944            let text_anchor =
5945                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5946            let anchor = Anchor::in_buffer(excerpt.id, text_anchor);
5947            match diff_base_anchor {
5948                Some(diff_base_anchor) => anchor.with_diff_base_anchor(diff_base_anchor),
5949                None => anchor,
5950            }
5951        } else if excerpt_offset == ExcerptDimension(MultiBufferOffset::ZERO) && bias == Bias::Left
5952        {
5953            Anchor::min()
5954        } else {
5955            Anchor::max()
5956        }
5957    }
5958
5959    /// Wraps the [`text::Anchor`] in a [`crate::Anchor`] if this multi-buffer is a singleton.
5960    pub fn as_singleton_anchor(&self, text_anchor: text::Anchor) -> Option<Anchor> {
5961        let (excerpt, buffer, _) = self.as_singleton()?;
5962        if text_anchor.buffer_id.is_none_or(|id| id == buffer) {
5963            Some(Anchor::in_buffer(excerpt, text_anchor))
5964        } else {
5965            None
5966        }
5967    }
5968
5969    /// Returns an anchor for the given excerpt and text anchor,
5970    /// Returns [`None`] if the excerpt_id is no longer valid or the text anchor range is out of excerpt's bounds.
5971    pub fn anchor_range_in_excerpt(
5972        &self,
5973        excerpt_id: ExcerptId,
5974        text_anchor: Range<text::Anchor>,
5975    ) -> Option<Range<Anchor>> {
5976        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
5977
5978        Some(
5979            Self::anchor_in_excerpt_(excerpt, text_anchor.start)?
5980                ..Self::anchor_in_excerpt_(excerpt, text_anchor.end)?,
5981        )
5982    }
5983
5984    /// Returns an anchor for the given excerpt and text anchor,
5985    /// Returns [`None`] if the excerpt_id is no longer valid or the text anchor range is out of excerpt's bounds.
5986    pub fn anchor_in_excerpt(
5987        &self,
5988        excerpt_id: ExcerptId,
5989        text_anchor: text::Anchor,
5990    ) -> Option<Anchor> {
5991        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
5992        Self::anchor_in_excerpt_(excerpt, text_anchor)
5993    }
5994
5995    /// Same as [`MultiBuffer::anchor_in_excerpt`], but more efficient than calling it multiple times.
5996    pub fn anchors_in_excerpt(
5997        &self,
5998        excerpt_id: ExcerptId,
5999        text_anchors: impl IntoIterator<Item = text::Anchor>,
6000    ) -> Option<impl Iterator<Item = Option<Anchor>>> {
6001        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
6002        Some(
6003            text_anchors
6004                .into_iter()
6005                .map(|text_anchor| Self::anchor_in_excerpt_(excerpt, text_anchor)),
6006        )
6007    }
6008
6009    fn anchor_in_excerpt_(excerpt: &Excerpt, text_anchor: text::Anchor) -> Option<Anchor> {
6010        match text_anchor.buffer_id {
6011            Some(buffer_id) if buffer_id == excerpt.buffer_id => (),
6012            Some(_) => return None,
6013            None if text_anchor.is_max() || text_anchor.is_min() => {
6014                return Some(Anchor::in_buffer(excerpt.id, text_anchor));
6015            }
6016            None => return None,
6017        }
6018
6019        let context = &excerpt.range.context;
6020        if context.start.cmp(&text_anchor, &excerpt.buffer).is_gt()
6021            || context.end.cmp(&text_anchor, &excerpt.buffer).is_lt()
6022        {
6023            return None;
6024        }
6025
6026        Some(Anchor::in_buffer(excerpt.id, text_anchor))
6027    }
6028
6029    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
6030        Some(self.excerpt(excerpt_id)?.range.context.clone())
6031    }
6032
6033    pub fn excerpt_range_for_excerpt(
6034        &self,
6035        excerpt_id: ExcerptId,
6036    ) -> Option<ExcerptRange<text::Anchor>> {
6037        Some(self.excerpt(excerpt_id)?.range.clone())
6038    }
6039
6040    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
6041        if anchor.is_min() || anchor.is_max() {
6042            // todo(lw): should be `!self.is_empty()`
6043            true
6044        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
6045            excerpt.buffer.can_resolve(&anchor.text_anchor)
6046        } else {
6047            false
6048        }
6049    }
6050
6051    pub fn excerpts(
6052        &self,
6053    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
6054        self.excerpts
6055            .iter()
6056            .map(|excerpt| (excerpt.id, &*excerpt.buffer, excerpt.range.clone()))
6057    }
6058
6059    fn cursor<'a, MBD, BD>(&'a self) -> MultiBufferCursor<'a, MBD, BD>
6060    where
6061        MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
6062        BD: TextDimension + AddAssign<<MBD as Sub>::Output>,
6063    {
6064        let excerpts = self.excerpts.cursor(());
6065        let diff_transforms = self.diff_transforms.cursor(());
6066        MultiBufferCursor {
6067            excerpts,
6068            diff_transforms,
6069            diffs: &self.diffs,
6070            cached_region: OnceCell::new(),
6071        }
6072    }
6073
6074    pub fn excerpt_before(&self, excerpt_id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
6075        let start_locator = self.excerpt_locator_for_id(excerpt_id);
6076        let mut excerpts = self
6077            .excerpts
6078            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
6079        excerpts.seek(&Some(start_locator), Bias::Left);
6080        excerpts.prev();
6081
6082        let mut diff_transforms = self
6083            .diff_transforms
6084            .cursor::<DiffTransforms<MultiBufferOffset>>(());
6085        diff_transforms.seek(&excerpts.start().1, Bias::Left);
6086        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
6087            diff_transforms.next();
6088        }
6089
6090        let excerpt = excerpts.item()?;
6091        Some(MultiBufferExcerpt {
6092            excerpt,
6093            offset: diff_transforms.start().output_dimension.0,
6094            buffer_offset: BufferOffset(excerpt.range.context.start.to_offset(&excerpt.buffer)),
6095            excerpt_offset: excerpts.start().1,
6096            diff_transforms,
6097        })
6098    }
6099
6100    pub fn excerpt_boundaries_in_range<R, T>(
6101        &self,
6102        range: R,
6103    ) -> impl Iterator<Item = ExcerptBoundary> + '_
6104    where
6105        R: RangeBounds<T>,
6106        T: ToOffset,
6107    {
6108        let start_offset;
6109        let start = match range.start_bound() {
6110            Bound::Included(start) => {
6111                start_offset = start.to_offset(self);
6112                Bound::Included(start_offset)
6113            }
6114            Bound::Excluded(_) => {
6115                panic!("not supported")
6116            }
6117            Bound::Unbounded => {
6118                start_offset = MultiBufferOffset::ZERO;
6119                Bound::Unbounded
6120            }
6121        };
6122        let end = match range.end_bound() {
6123            Bound::Included(end) => Bound::Included(end.to_offset(self)),
6124            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
6125            Bound::Unbounded => Bound::Unbounded,
6126        };
6127        let bounds = (start, end);
6128        let mut cursor = self.cursor::<DimensionPair<MultiBufferOffset, Point>, BufferOffset>();
6129        cursor.seek(&DimensionPair {
6130            key: start_offset,
6131            value: None,
6132        });
6133
6134        if cursor
6135            .fetch_excerpt_with_range()
6136            .is_some_and(|(_, range)| bounds.contains(&range.start.key))
6137        {
6138            cursor.prev_excerpt();
6139        } else {
6140            cursor.seek_to_start_of_current_excerpt();
6141        }
6142        let mut prev_region = cursor
6143            .fetch_excerpt_with_range()
6144            .map(|(excerpt, _)| excerpt);
6145
6146        cursor.next_excerpt_forwards();
6147
6148        iter::from_fn(move || {
6149            loop {
6150                if self.singleton {
6151                    return None;
6152                }
6153
6154                let (next_excerpt, next_range) = cursor.fetch_excerpt_with_range()?;
6155                cursor.next_excerpt_forwards();
6156                if !bounds.contains(&next_range.start.key) {
6157                    prev_region = Some(next_excerpt);
6158                    continue;
6159                }
6160
6161                let next_region_start = next_range.start.value.unwrap();
6162                let next_region_end = if let Some((_, range)) = cursor.fetch_excerpt_with_range() {
6163                    range.start.value.unwrap()
6164                } else {
6165                    self.max_point()
6166                };
6167
6168                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
6169                    id: region.id,
6170                    buffer: region.buffer.clone(),
6171                    buffer_id: region.buffer_id,
6172                    range: region.range.clone(),
6173                    end_row: MultiBufferRow(next_region_start.row),
6174                });
6175
6176                let next = ExcerptInfo {
6177                    id: next_excerpt.id,
6178                    buffer: next_excerpt.buffer.clone(),
6179                    buffer_id: next_excerpt.buffer_id,
6180                    range: next_excerpt.range.clone(),
6181                    end_row: if next_excerpt.has_trailing_newline {
6182                        MultiBufferRow(next_region_end.row - 1)
6183                    } else {
6184                        MultiBufferRow(next_region_end.row)
6185                    },
6186                };
6187
6188                let row = MultiBufferRow(next_region_start.row);
6189
6190                prev_region = Some(next_excerpt);
6191
6192                return Some(ExcerptBoundary { row, prev, next });
6193            }
6194        })
6195    }
6196
6197    pub fn edit_count(&self) -> usize {
6198        self.edit_count
6199    }
6200
6201    pub fn non_text_state_update_count(&self) -> usize {
6202        self.non_text_state_update_count
6203    }
6204
6205    /// Returns the smallest enclosing bracket ranges containing the given range or
6206    /// None if no brackets contain range or the range is not contained in a single
6207    /// excerpt
6208    ///
6209    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
6210    #[ztracing::instrument(skip_all)]
6211    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
6212        &self,
6213        range: Range<T>,
6214        range_filter: Option<
6215            &dyn Fn(&BufferSnapshot, Range<BufferOffset>, Range<BufferOffset>) -> bool,
6216        >,
6217    ) -> Option<(Range<MultiBufferOffset>, Range<MultiBufferOffset>)> {
6218        let range = range.start.to_offset(self)..range.end.to_offset(self);
6219        let mut excerpt = self.excerpt_containing(range.clone())?;
6220        let buffer = excerpt.buffer();
6221        let excerpt_buffer_range = excerpt.buffer_range();
6222
6223        // Filter to ranges contained in the excerpt
6224        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
6225            excerpt_buffer_range.contains(&BufferOffset(open.start))
6226                && excerpt_buffer_range.contains(&BufferOffset(close.end))
6227                && range_filter.is_none_or(|filter| {
6228                    filter(
6229                        buffer,
6230                        BufferOffset(open.start)..BufferOffset(close.end),
6231                        BufferOffset(close.start)..BufferOffset(close.end),
6232                    )
6233                })
6234        };
6235
6236        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
6237            excerpt.map_range_to_buffer(range),
6238            Some(&range_filter),
6239        )?;
6240
6241        Some((
6242            excerpt.map_range_from_buffer(BufferOffset(open.start)..BufferOffset(open.end)),
6243            excerpt.map_range_from_buffer(BufferOffset(close.start)..BufferOffset(close.end)),
6244        ))
6245    }
6246
6247    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
6248    /// not contained in a single excerpt
6249    pub fn enclosing_bracket_ranges<T: ToOffset>(
6250        &self,
6251        range: Range<T>,
6252    ) -> Option<impl Iterator<Item = (Range<MultiBufferOffset>, Range<MultiBufferOffset>)> + '_>
6253    {
6254        let range = range.start.to_offset(self)..range.end.to_offset(self);
6255        let mut excerpt = self.excerpt_containing(range.clone())?;
6256
6257        Some(
6258            excerpt
6259                .buffer()
6260                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
6261                .filter_map(move |pair| {
6262                    let open_range =
6263                        BufferOffset(pair.open_range.start)..BufferOffset(pair.open_range.end);
6264                    let close_range =
6265                        BufferOffset(pair.close_range.start)..BufferOffset(pair.close_range.end);
6266                    if excerpt.contains_buffer_range(open_range.start..close_range.end) {
6267                        Some((
6268                            excerpt.map_range_from_buffer(open_range),
6269                            excerpt.map_range_from_buffer(close_range),
6270                        ))
6271                    } else {
6272                        None
6273                    }
6274                }),
6275        )
6276    }
6277
6278    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
6279    /// not contained in a single excerpt
6280    pub fn text_object_ranges<T: ToOffset>(
6281        &self,
6282        range: Range<T>,
6283        options: TreeSitterOptions,
6284    ) -> impl Iterator<Item = (Range<MultiBufferOffset>, TextObject)> + '_ {
6285        let range = range.start.to_offset(self)..range.end.to_offset(self);
6286        self.excerpt_containing(range.clone())
6287            .map(|mut excerpt| {
6288                excerpt
6289                    .buffer()
6290                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
6291                    .filter_map(move |(range, text_object)| {
6292                        let range = BufferOffset(range.start)..BufferOffset(range.end);
6293                        if excerpt.contains_buffer_range(range.clone()) {
6294                            Some((excerpt.map_range_from_buffer(range), text_object))
6295                        } else {
6296                            None
6297                        }
6298                    })
6299            })
6300            .into_iter()
6301            .flatten()
6302    }
6303
6304    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
6305    /// not contained in a single excerpt
6306    pub fn bracket_ranges<T: ToOffset>(
6307        &self,
6308        range: Range<T>,
6309    ) -> Option<impl Iterator<Item = (Range<MultiBufferOffset>, Range<MultiBufferOffset>)> + '_>
6310    {
6311        let range = range.start.to_offset(self)..range.end.to_offset(self);
6312        let mut excerpt = self.excerpt_containing(range.clone())?;
6313        Some(
6314            excerpt
6315                .buffer()
6316                .bracket_ranges(excerpt.map_range_to_buffer(range))
6317                .filter_map(move |pair| {
6318                    let open_range =
6319                        BufferOffset(pair.open_range.start)..BufferOffset(pair.open_range.end);
6320                    let close_range =
6321                        BufferOffset(pair.close_range.start)..BufferOffset(pair.close_range.end);
6322                    excerpt
6323                        .contains_buffer_range(open_range.start..close_range.end)
6324                        .then(|| BracketMatch {
6325                            open_range: excerpt.map_range_from_buffer(open_range),
6326                            close_range: excerpt.map_range_from_buffer(close_range),
6327                            color_index: pair.color_index,
6328                            newline_only: pair.newline_only,
6329                            syntax_layer_depth: pair.syntax_layer_depth,
6330                        })
6331                })
6332                .map(BracketMatch::bracket_ranges),
6333        )
6334    }
6335
6336    pub fn redacted_ranges<'a, T: ToOffset>(
6337        &'a self,
6338        range: Range<T>,
6339        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
6340    ) -> impl Iterator<Item = Range<MultiBufferOffset>> + 'a {
6341        let range = range.start.to_offset(self)..range.end.to_offset(self);
6342        self.lift_buffer_metadata(range, move |buffer, range| {
6343            if redaction_enabled(buffer.file()) {
6344                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
6345            } else {
6346                None
6347            }
6348        })
6349        .map(|(range, _, _)| range)
6350    }
6351
6352    pub fn runnable_ranges(
6353        &self,
6354        range: Range<Anchor>,
6355    ) -> impl Iterator<Item = (Range<Anchor>, language::RunnableRange)> + '_ {
6356        let range = range.start.to_offset(self)..range.end.to_offset(self);
6357        self.lift_buffer_metadata(range, move |buffer, range| {
6358            Some(
6359                buffer
6360                    .runnable_ranges(range.clone())
6361                    .filter(move |runnable| {
6362                        runnable.run_range.start >= range.start
6363                            && runnable.run_range.end < range.end
6364                    })
6365                    .map(|runnable| (runnable.run_range.clone(), runnable)),
6366            )
6367        })
6368        .map(|(run_range, runnable, _)| {
6369            (
6370                self.anchor_after(run_range.start)..self.anchor_before(run_range.end),
6371                runnable,
6372            )
6373        })
6374    }
6375
6376    pub fn line_indents(
6377        &self,
6378        start_row: MultiBufferRow,
6379        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
6380    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
6381        let max_point = self.max_point();
6382        let mut cursor = self.cursor::<Point, Point>();
6383        cursor.seek(&Point::new(start_row.0, 0));
6384        iter::from_fn(move || {
6385            let mut region = cursor.region()?;
6386            while !buffer_filter(&region.excerpt.buffer) {
6387                cursor.next();
6388                region = cursor.region()?;
6389            }
6390            let region = cursor.region()?;
6391            let overshoot = start_row.0.saturating_sub(region.range.start.row);
6392            let buffer_start_row =
6393                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
6394
6395            let buffer_end_row = if region.is_main_buffer
6396                && (region.has_trailing_newline || region.range.end == max_point)
6397            {
6398                region.buffer_range.end.row
6399            } else {
6400                region.buffer_range.end.row.saturating_sub(1)
6401            };
6402
6403            let line_indents = region
6404                .buffer
6405                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
6406            let region_buffer_row = region.buffer_range.start.row;
6407            let region_row = region.range.start.row;
6408            let region_buffer = &region.excerpt.buffer;
6409            cursor.next();
6410            Some(line_indents.map(move |(buffer_row, indent)| {
6411                let row = region_row + (buffer_row - region_buffer_row);
6412                (MultiBufferRow(row), indent, region_buffer.as_ref())
6413            }))
6414        })
6415        .flatten()
6416    }
6417
6418    pub fn reversed_line_indents(
6419        &self,
6420        end_row: MultiBufferRow,
6421        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
6422    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
6423        let max_point = self.max_point();
6424        let mut cursor = self.cursor::<Point, Point>();
6425        cursor.seek(&Point::new(end_row.0, 0));
6426        iter::from_fn(move || {
6427            let mut region = cursor.region()?;
6428            while !buffer_filter(&region.excerpt.buffer) {
6429                cursor.prev();
6430                region = cursor.region()?;
6431            }
6432            let region = cursor.region()?;
6433
6434            let buffer_start_row = region.buffer_range.start.row;
6435            let buffer_end_row = if region.is_main_buffer
6436                && (region.has_trailing_newline || region.range.end == max_point)
6437            {
6438                region.buffer_range.end.row + 1
6439            } else {
6440                region.buffer_range.end.row
6441            };
6442
6443            let overshoot = end_row.0 - region.range.start.row;
6444            let buffer_end_row =
6445                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
6446
6447            let line_indents = region
6448                .buffer
6449                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
6450            let region_buffer_row = region.buffer_range.start.row;
6451            let region_row = region.range.start.row;
6452            let region_buffer = &region.excerpt.buffer;
6453            cursor.prev();
6454            Some(line_indents.map(move |(buffer_row, indent)| {
6455                let row = region_row + (buffer_row - region_buffer_row);
6456                (MultiBufferRow(row), indent, region_buffer.as_ref())
6457            }))
6458        })
6459        .flatten()
6460    }
6461
6462    pub async fn enclosing_indent(
6463        &self,
6464        mut target_row: MultiBufferRow,
6465    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
6466        let max_row = MultiBufferRow(self.max_point().row);
6467        if target_row >= max_row {
6468            return None;
6469        }
6470
6471        let mut target_indent = self.line_indent_for_row(target_row);
6472
6473        // If the current row is at the start of an indented block, we want to return this
6474        // block as the enclosing indent.
6475        if !target_indent.is_line_empty() && target_row < max_row {
6476            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
6477            if !next_line_indent.is_line_empty()
6478                && target_indent.raw_len() < next_line_indent.raw_len()
6479            {
6480                target_indent = next_line_indent;
6481                target_row.0 += 1;
6482            }
6483        }
6484
6485        const SEARCH_ROW_LIMIT: u32 = 25000;
6486        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
6487        const YIELD_INTERVAL: u32 = 100;
6488
6489        let mut accessed_row_counter = 0;
6490
6491        // If there is a blank line at the current row, search for the next non indented lines
6492        if target_indent.is_line_empty() {
6493            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
6494            let end =
6495                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
6496
6497            let mut non_empty_line_above = None;
6498            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
6499                if row < start {
6500                    break;
6501                }
6502                accessed_row_counter += 1;
6503                if accessed_row_counter == YIELD_INTERVAL {
6504                    accessed_row_counter = 0;
6505                    yield_now().await;
6506                }
6507                if !indent.is_line_empty() {
6508                    non_empty_line_above = Some((row, indent));
6509                    break;
6510                }
6511            }
6512
6513            let mut non_empty_line_below = None;
6514            for (row, indent, _) in self.line_indents(target_row, |_| true) {
6515                if row > end {
6516                    break;
6517                }
6518                accessed_row_counter += 1;
6519                if accessed_row_counter == YIELD_INTERVAL {
6520                    accessed_row_counter = 0;
6521                    yield_now().await;
6522                }
6523                if !indent.is_line_empty() {
6524                    non_empty_line_below = Some((row, indent));
6525                    break;
6526                }
6527            }
6528
6529            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
6530                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
6531                    if above_indent.raw_len() >= below_indent.raw_len() {
6532                        (above_row, above_indent)
6533                    } else {
6534                        (below_row, below_indent)
6535                    }
6536                }
6537                (Some(above), None) => above,
6538                (None, Some(below)) => below,
6539                _ => return None,
6540            };
6541
6542            target_indent = indent;
6543            target_row = row;
6544        }
6545
6546        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
6547        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
6548
6549        let mut start_indent = None;
6550        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
6551            if row < start {
6552                break;
6553            }
6554            accessed_row_counter += 1;
6555            if accessed_row_counter == YIELD_INTERVAL {
6556                accessed_row_counter = 0;
6557                yield_now().await;
6558            }
6559            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
6560                start_indent = Some((row, indent));
6561                break;
6562            }
6563        }
6564        let (start_row, start_indent_size) = start_indent?;
6565
6566        let mut end_indent = (end, None);
6567        for (row, indent, _) in self.line_indents(target_row, |_| true) {
6568            if row > end {
6569                break;
6570            }
6571            accessed_row_counter += 1;
6572            if accessed_row_counter == YIELD_INTERVAL {
6573                accessed_row_counter = 0;
6574                yield_now().await;
6575            }
6576            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
6577                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
6578                break;
6579            }
6580        }
6581        let (end_row, end_indent_size) = end_indent;
6582
6583        let indent = if let Some(end_indent_size) = end_indent_size {
6584            if start_indent_size.raw_len() > end_indent_size.raw_len() {
6585                start_indent_size
6586            } else {
6587                end_indent_size
6588            }
6589        } else {
6590            start_indent_size
6591        };
6592
6593        Some((start_row..end_row, indent))
6594    }
6595
6596    pub fn indent_guides_in_range<T: ToPoint>(
6597        &self,
6598        range: Range<T>,
6599        ignore_disabled_for_language: bool,
6600        cx: &App,
6601    ) -> impl Iterator<Item = IndentGuide> {
6602        let range = range.start.to_point(self)..range.end.to_point(self);
6603        let start_row = MultiBufferRow(range.start.row);
6604        let end_row = MultiBufferRow(range.end.row);
6605
6606        let mut row_indents = self.line_indents(start_row, |buffer| {
6607            let settings =
6608                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
6609            settings.indent_guides.enabled || ignore_disabled_for_language
6610        });
6611
6612        let mut result = Vec::new();
6613        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
6614
6615        let mut prev_settings = None;
6616        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
6617            if first_row > end_row {
6618                break;
6619            }
6620            let current_depth = indent_stack.len() as u32;
6621
6622            // Avoid retrieving the language settings repeatedly for every buffer row.
6623            if let Some((prev_buffer_id, _)) = &prev_settings
6624                && prev_buffer_id != &buffer.remote_id()
6625            {
6626                prev_settings.take();
6627            }
6628            let settings = &prev_settings
6629                .get_or_insert_with(|| {
6630                    (
6631                        buffer.remote_id(),
6632                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
6633                    )
6634                })
6635                .1;
6636            let tab_size = settings.tab_size.get();
6637
6638            // When encountering empty, continue until found useful line indent
6639            // then add to the indent stack with the depth found
6640            let mut found_indent = false;
6641            let mut last_row = first_row;
6642            if line_indent.is_line_blank() {
6643                while !found_indent {
6644                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
6645                        break;
6646                    };
6647                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
6648                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
6649                        break;
6650                    }
6651
6652                    if new_line_indent.is_line_blank() {
6653                        continue;
6654                    }
6655                    last_row = target_row.min(end_row);
6656                    line_indent = new_line_indent;
6657                    found_indent = true;
6658                    break;
6659                }
6660            } else {
6661                found_indent = true
6662            }
6663
6664            let depth = if found_indent {
6665                line_indent.len(tab_size) / tab_size
6666            } else {
6667                0
6668            };
6669
6670            match depth.cmp(&current_depth) {
6671                cmp::Ordering::Less => {
6672                    for _ in 0..(current_depth - depth) {
6673                        let mut indent = indent_stack.pop().unwrap();
6674                        if last_row != first_row {
6675                            // In this case, we landed on an empty row, had to seek forward,
6676                            // and discovered that the indent we where on is ending.
6677                            // This means that the last display row must
6678                            // be on line that ends this indent range, so we
6679                            // should display the range up to the first non-empty line
6680                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
6681                        }
6682
6683                        result.push(indent)
6684                    }
6685                }
6686                cmp::Ordering::Greater => {
6687                    for next_depth in current_depth..depth {
6688                        indent_stack.push(IndentGuide {
6689                            buffer_id: buffer.remote_id(),
6690                            start_row: first_row,
6691                            end_row: last_row,
6692                            depth: next_depth,
6693                            tab_size,
6694                            settings: settings.indent_guides.clone(),
6695                        });
6696                    }
6697                }
6698                _ => {}
6699            }
6700
6701            for indent in indent_stack.iter_mut() {
6702                indent.end_row = last_row;
6703            }
6704        }
6705
6706        result.extend(indent_stack);
6707        result.into_iter()
6708    }
6709
6710    pub fn trailing_excerpt_update_count(&self) -> usize {
6711        self.trailing_excerpt_update_count
6712    }
6713
6714    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
6715        self.point_to_buffer_offset(point)
6716            .and_then(|(buffer, _)| buffer.file())
6717    }
6718
6719    pub fn language_at<T: ToOffset>(&self, offset: T) -> Option<&Arc<Language>> {
6720        self.point_to_buffer_offset(offset)
6721            .and_then(|(buffer, offset)| buffer.language_at(offset))
6722    }
6723
6724    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
6725        self.excerpts
6726            .first()
6727            .map(|excerpt| &excerpt.buffer)
6728            .map(|buffer| {
6729                language_settings(
6730                    buffer.language().map(|language| language.name()),
6731                    buffer.file(),
6732                    cx,
6733                )
6734            })
6735            .unwrap_or_else(move || self.language_settings_at(MultiBufferOffset::ZERO, cx))
6736    }
6737
6738    pub fn language_settings_at<'a, T: ToOffset>(
6739        &'a self,
6740        point: T,
6741        cx: &'a App,
6742    ) -> Cow<'a, LanguageSettings> {
6743        let mut language = None;
6744        let mut file = None;
6745        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
6746            language = buffer.language_at(offset);
6747            file = buffer.file();
6748        }
6749        language_settings(language.map(|l| l.name()), file, cx)
6750    }
6751
6752    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
6753        self.point_to_buffer_offset(point)
6754            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
6755    }
6756
6757    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
6758        self.point_to_buffer_offset(point)
6759            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
6760            .unwrap_or_default()
6761    }
6762
6763    pub fn language_indent_size_at<T: ToOffset>(
6764        &self,
6765        position: T,
6766        cx: &App,
6767    ) -> Option<IndentSize> {
6768        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
6769        Some(buffer_snapshot.language_indent_size_at(offset, cx))
6770    }
6771
6772    pub fn is_dirty(&self) -> bool {
6773        self.is_dirty
6774    }
6775
6776    pub fn has_deleted_file(&self) -> bool {
6777        self.has_deleted_file
6778    }
6779
6780    pub fn has_conflict(&self) -> bool {
6781        self.has_conflict
6782    }
6783
6784    pub fn has_diagnostics(&self) -> bool {
6785        self.excerpts
6786            .iter()
6787            .any(|excerpt| excerpt.buffer.has_diagnostics())
6788    }
6789
6790    pub fn diagnostic_group(
6791        &self,
6792        buffer_id: BufferId,
6793        group_id: usize,
6794    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
6795        self.lift_buffer_metadata::<Point, _, _>(
6796            Point::zero()..self.max_point(),
6797            move |buffer, range| {
6798                if buffer.remote_id() != buffer_id {
6799                    return None;
6800                };
6801                Some(
6802                    buffer
6803                        .diagnostics_in_range(range, false)
6804                        .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
6805                        .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
6806                )
6807            },
6808        )
6809        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6810    }
6811
6812    pub fn diagnostics_in_range<'a, MBD>(
6813        &'a self,
6814        range: Range<MBD>,
6815    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, MBD>> + 'a
6816    where
6817        MBD::TextDimension: 'a
6818            + text::ToOffset
6819            + text::FromAnchor
6820            + Sub<Output = MBD::TextDimension>
6821            + fmt::Debug
6822            + ops::Add<Output = MBD::TextDimension>
6823            + ops::AddAssign
6824            + Ord,
6825        MBD: MultiBufferDimension
6826            + Ord
6827            + Sub<Output = MBD::TextDimension>
6828            + ops::Add<MBD::TextDimension, Output = MBD>
6829            + ops::AddAssign<MBD::TextDimension>
6830            + 'a,
6831    {
6832        self.lift_buffer_metadata::<MBD, _, _>(range, move |buffer, buffer_range| {
6833            Some(
6834                buffer
6835                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6836                    .map(|entry| (entry.range, entry.diagnostic)),
6837            )
6838        })
6839        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6840    }
6841
6842    pub fn diagnostics_with_buffer_ids_in_range<'a, MBD>(
6843        &'a self,
6844        range: Range<MBD>,
6845    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, MBD>)> + 'a
6846    where
6847        MBD: MultiBufferDimension
6848            + Ord
6849            + Sub<Output = MBD::TextDimension>
6850            + ops::Add<MBD::TextDimension, Output = MBD>
6851            + ops::AddAssign<MBD::TextDimension>,
6852        MBD::TextDimension: Sub<Output = MBD::TextDimension>
6853            + ops::Add<Output = MBD::TextDimension>
6854            + text::ToOffset
6855            + text::FromAnchor
6856            + AddAssign<MBD::TextDimension>
6857            + Ord,
6858    {
6859        self.lift_buffer_metadata::<MBD, _, _>(range, move |buffer, buffer_range| {
6860            Some(
6861                buffer
6862                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6863                    .map(|entry| (entry.range, entry.diagnostic)),
6864            )
6865        })
6866        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6867    }
6868
6869    pub fn syntax_ancestor<T: ToOffset>(
6870        &self,
6871        range: Range<T>,
6872    ) -> Option<(tree_sitter::Node<'_>, Range<MultiBufferOffset>)> {
6873        let range = range.start.to_offset(self)..range.end.to_offset(self);
6874        let mut excerpt = self.excerpt_containing(range.clone())?;
6875        let node = excerpt
6876            .buffer()
6877            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6878        let node_range = node.byte_range();
6879        let node_range = BufferOffset(node_range.start)..BufferOffset(node_range.end);
6880        if !excerpt.contains_buffer_range(node_range.clone()) {
6881            return None;
6882        };
6883        Some((node, excerpt.map_range_from_buffer(node_range)))
6884    }
6885
6886    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6887        let (excerpt_id, _, buffer) = self.as_singleton()?;
6888        let outline = buffer.outline(theme);
6889        Some(Outline::new(
6890            outline
6891                .items
6892                .into_iter()
6893                .flat_map(|item| {
6894                    Some(OutlineItem {
6895                        depth: item.depth,
6896                        range: self.anchor_range_in_excerpt(excerpt_id, item.range)?,
6897                        source_range_for_text: self
6898                            .anchor_range_in_excerpt(excerpt_id, item.source_range_for_text)?,
6899                        text: item.text,
6900                        highlight_ranges: item.highlight_ranges,
6901                        name_ranges: item.name_ranges,
6902                        body_range: item.body_range.and_then(|body_range| {
6903                            self.anchor_range_in_excerpt(excerpt_id, body_range)
6904                        }),
6905                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6906                            self.anchor_range_in_excerpt(excerpt_id, annotation_range)
6907                        }),
6908                    })
6909                })
6910                .collect(),
6911        ))
6912    }
6913
6914    pub fn symbols_containing<T: ToOffset>(
6915        &self,
6916        offset: T,
6917        theme: Option<&SyntaxTheme>,
6918    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6919        let anchor = self.anchor_before(offset);
6920        let excerpt @ &Excerpt {
6921            id: excerpt_id,
6922            buffer_id,
6923            ref buffer,
6924            ..
6925        } = self.excerpt(anchor.excerpt_id)?;
6926        if cfg!(debug_assertions) {
6927            match anchor.text_anchor.buffer_id {
6928                // we clearly are hitting this according to sentry, but in what situations can this occur?
6929                Some(anchor_buffer_id) => {
6930                    assert_eq!(
6931                        anchor_buffer_id, buffer_id,
6932                        "anchor {anchor:?} does not match with resolved excerpt {excerpt:?}"
6933                    )
6934                }
6935                None => assert!(anchor.is_max()),
6936            }
6937        };
6938        Some((
6939            buffer_id,
6940            buffer
6941                .symbols_containing(anchor.text_anchor, theme)
6942                .into_iter()
6943                .flat_map(|item| {
6944                    Some(OutlineItem {
6945                        depth: item.depth,
6946                        source_range_for_text: Anchor::range_in_buffer(
6947                            excerpt_id,
6948                            item.source_range_for_text,
6949                        ),
6950                        range: Anchor::range_in_buffer(excerpt_id, item.range),
6951                        text: item.text,
6952                        highlight_ranges: item.highlight_ranges,
6953                        name_ranges: item.name_ranges,
6954                        body_range: item
6955                            .body_range
6956                            .map(|body_range| Anchor::range_in_buffer(excerpt_id, body_range)),
6957                        annotation_range: item
6958                            .annotation_range
6959                            .map(|body_range| Anchor::range_in_buffer(excerpt_id, body_range)),
6960                    })
6961                })
6962                .collect(),
6963        ))
6964    }
6965
6966    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6967        self.try_excerpt_locator_for_id(id)
6968            .unwrap_or_else(|| panic!("invalid excerpt id {id:?}"))
6969    }
6970
6971    fn try_excerpt_locator_for_id(&self, id: ExcerptId) -> Option<&Locator> {
6972        if id == ExcerptId::min() {
6973            Some(Locator::min_ref())
6974        } else if id == ExcerptId::max() {
6975            Some(Locator::max_ref())
6976        } else {
6977            let (_, _, item) = self.excerpt_ids.find::<ExcerptId, _>((), &id, Bias::Left);
6978            if let Some(entry) = item
6979                && entry.id == id
6980            {
6981                return Some(&entry.locator);
6982            }
6983            None
6984        }
6985    }
6986
6987    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6988    fn excerpt_locators_for_ids(
6989        &self,
6990        ids: impl IntoIterator<Item = ExcerptId>,
6991    ) -> SmallVec<[Locator; 1]> {
6992        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6993        sorted_ids.sort_unstable();
6994        sorted_ids.dedup();
6995        let mut locators = SmallVec::new();
6996
6997        while sorted_ids.last() == Some(&ExcerptId::max()) {
6998            sorted_ids.pop();
6999            locators.push(Locator::max());
7000        }
7001
7002        let mut sorted_ids = sorted_ids.into_iter().peekable();
7003        locators.extend(
7004            sorted_ids
7005                .peeking_take_while(|excerpt| *excerpt == ExcerptId::min())
7006                .map(|_| Locator::min()),
7007        );
7008
7009        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
7010        for id in sorted_ids {
7011            if cursor.seek_forward(&id, Bias::Left) {
7012                locators.push(cursor.item().unwrap().locator.clone());
7013            } else {
7014                panic!("invalid excerpt id {:?}", id);
7015            }
7016        }
7017
7018        locators.sort_unstable();
7019        locators
7020    }
7021
7022    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
7023        Some(self.excerpt(excerpt_id)?.buffer_id)
7024    }
7025
7026    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
7027        Some(&self.excerpt(excerpt_id)?.buffer)
7028    }
7029
7030    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
7031        let mut cursor = self
7032            .excerpts
7033            .cursor::<Dimensions<Option<&Locator>, ExcerptPoint>>(());
7034        let locator = self.excerpt_locator_for_id(excerpt_id);
7035        let mut sought_exact = cursor.seek(&Some(locator), Bias::Left);
7036        if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
7037            sought_exact = true;
7038            cursor.prev();
7039        } else if excerpt_id == ExcerptId::min() {
7040            sought_exact = true;
7041        }
7042        if sought_exact {
7043            let start = cursor.start().1;
7044            let end = cursor.end().1;
7045            let mut diff_transforms = self
7046                .diff_transforms
7047                .cursor::<Dimensions<ExcerptPoint, OutputDimension<Point>>>(());
7048            diff_transforms.seek(&start, Bias::Left);
7049            let overshoot = start - diff_transforms.start().0;
7050            let start = diff_transforms.start().1 + overshoot;
7051            diff_transforms.seek(&end, Bias::Right);
7052            let overshoot = end - diff_transforms.start().0;
7053            let end = diff_transforms.start().1 + overshoot;
7054            Some(start.0..end.0)
7055        } else {
7056            None
7057        }
7058    }
7059
7060    /// Returns the excerpt for the given id. The returned excerpt is guaranteed
7061    /// to have the latest excerpt id for the one passed in and will also remap
7062    /// `ExcerptId::max()` to the corresponding excertp ID.
7063    ///
7064    /// Callers of this function should generally use the resulting excerpt's `id` field
7065    /// afterwards.
7066    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
7067        let excerpt_id = self.latest_excerpt_id(excerpt_id);
7068        let locator = self.try_excerpt_locator_for_id(excerpt_id)?;
7069        let (_, _, item) =
7070            self.excerpts
7071                .find::<Option<&Locator>, _>((), &Some(locator), Bias::Left);
7072        if let Some(excerpt) = item
7073            && excerpt.id == excerpt_id
7074        {
7075            return Some(excerpt);
7076        } else if item.is_none() && excerpt_id == ExcerptId::max() {
7077            return self.excerpts.last();
7078        }
7079        None
7080    }
7081
7082    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
7083    pub fn excerpt_containing<T: ToOffset>(
7084        &self,
7085        range: Range<T>,
7086    ) -> Option<MultiBufferExcerpt<'_>> {
7087        let range = range.start.to_offset(self)..range.end.to_offset(self);
7088        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
7089        cursor.seek(&range.start);
7090
7091        let start_excerpt = cursor.excerpt()?;
7092        if range.end != range.start {
7093            cursor.seek_forward(&range.end);
7094            if cursor.excerpt()?.id != start_excerpt.id {
7095                return None;
7096            }
7097        }
7098
7099        cursor.seek_to_start_of_current_excerpt();
7100        let region = cursor.region()?;
7101        let offset = region.range.start;
7102        let buffer_offset = start_excerpt.buffer_start_offset();
7103        let excerpt_offset = *cursor.excerpts.start();
7104        Some(MultiBufferExcerpt {
7105            diff_transforms: cursor.diff_transforms,
7106            excerpt: start_excerpt,
7107            offset,
7108            buffer_offset,
7109            excerpt_offset,
7110        })
7111    }
7112
7113    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
7114        if let Some(id) = anchor.text_anchor.buffer_id {
7115            return Some(id);
7116        }
7117        let excerpt = self.excerpt_containing(anchor..anchor)?;
7118        Some(excerpt.buffer_id())
7119    }
7120
7121    pub fn selections_in_range<'a>(
7122        &'a self,
7123        range: &'a Range<Anchor>,
7124        include_local: bool,
7125    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
7126        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
7127        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
7128        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
7129        cursor.seek(start_locator, Bias::Left);
7130        cursor
7131            .take_while(move |excerpt| excerpt.locator <= *end_locator)
7132            .flat_map(move |excerpt| {
7133                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
7134                if excerpt.id == range.start.excerpt_id {
7135                    query_range.start = range.start.text_anchor;
7136                }
7137                if excerpt.id == range.end.excerpt_id {
7138                    query_range.end = range.end.text_anchor;
7139                }
7140
7141                excerpt
7142                    .buffer
7143                    .selections_in_range(query_range, include_local)
7144                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
7145                        selections.map(move |selection| {
7146                            let mut start = Anchor::in_buffer(excerpt.id, selection.start);
7147                            let mut end = Anchor::in_buffer(excerpt.id, selection.end);
7148                            if range.start.cmp(&start, self).is_gt() {
7149                                start = range.start;
7150                            }
7151                            if range.end.cmp(&end, self).is_lt() {
7152                                end = range.end;
7153                            }
7154
7155                            (
7156                                replica_id,
7157                                line_mode,
7158                                cursor_shape,
7159                                Selection {
7160                                    id: selection.id,
7161                                    start,
7162                                    end,
7163                                    reversed: selection.reversed,
7164                                    goal: selection.goal,
7165                                },
7166                            )
7167                        })
7168                    })
7169            })
7170    }
7171
7172    pub fn show_headers(&self) -> bool {
7173        self.show_headers
7174    }
7175
7176    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
7177        self.diffs.get(&buffer_id).map(|diff| &diff.diff)
7178    }
7179
7180    pub fn all_diff_hunks_expanded(&self) -> bool {
7181        self.all_diff_hunks_expanded
7182    }
7183
7184    /// Visually annotates a position or range with the `Debug` representation of a value. The
7185    /// callsite of this function is used as a key - previous annotations will be removed.
7186    #[cfg(debug_assertions)]
7187    #[track_caller]
7188    pub fn debug<V, R>(&self, ranges: &R, value: V)
7189    where
7190        R: debug::ToMultiBufferDebugRanges,
7191        V: std::fmt::Debug,
7192    {
7193        self.debug_with_key(std::panic::Location::caller(), ranges, value);
7194    }
7195
7196    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
7197    /// debug annotations with the same key will be removed. The key is also used to determine the
7198    /// annotation's color.
7199    #[cfg(debug_assertions)]
7200    #[track_caller]
7201    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
7202    where
7203        K: std::hash::Hash + 'static,
7204        R: debug::ToMultiBufferDebugRanges,
7205        V: std::fmt::Debug,
7206    {
7207        let text_ranges = ranges
7208            .to_multi_buffer_debug_ranges(self)
7209            .into_iter()
7210            .flat_map(|range| {
7211                self.range_to_buffer_ranges(range.start..=range.end)
7212                    .into_iter()
7213                    .map(|(buffer, range, _excerpt_id)| {
7214                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
7215                    })
7216            })
7217            .collect();
7218        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
7219            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
7220        });
7221    }
7222
7223    fn excerpt_edits_for_diff_change(
7224        &self,
7225        buffer_state: &BufferState,
7226        diff_change_range: Range<usize>,
7227    ) -> Vec<Edit<ExcerptDimension<MultiBufferOffset>>> {
7228        let mut excerpt_edits = Vec::new();
7229        for locator in &buffer_state.excerpts {
7230            let mut cursor = self
7231                .excerpts
7232                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
7233            cursor.seek_forward(&Some(locator), Bias::Left);
7234            if let Some(excerpt) = cursor.item()
7235                && excerpt.locator == *locator
7236            {
7237                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
7238                if diff_change_range.end < excerpt_buffer_range.start
7239                    || diff_change_range.start > excerpt_buffer_range.end
7240                {
7241                    continue;
7242                }
7243                let excerpt_start = cursor.start().1;
7244                let excerpt_len = excerpt.text_summary.len;
7245                let diff_change_start_in_excerpt = diff_change_range
7246                    .start
7247                    .saturating_sub(excerpt_buffer_range.start);
7248                let diff_change_end_in_excerpt = diff_change_range
7249                    .end
7250                    .saturating_sub(excerpt_buffer_range.start);
7251                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
7252                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
7253                excerpt_edits.push(Edit {
7254                    old: edit_start..edit_end,
7255                    new: edit_start..edit_end,
7256                });
7257            }
7258        }
7259        excerpt_edits
7260    }
7261}
7262
7263#[cfg(any(test, feature = "test-support"))]
7264impl MultiBufferSnapshot {
7265    pub fn random_byte_range(
7266        &self,
7267        start_offset: MultiBufferOffset,
7268        rng: &mut impl rand::Rng,
7269    ) -> Range<MultiBufferOffset> {
7270        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
7271        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
7272        start..end
7273    }
7274
7275    #[cfg(any(test, feature = "test-support"))]
7276    fn check_invariants(&self) {
7277        let excerpts = self.excerpts.items(());
7278        let excerpt_ids = self.excerpt_ids.items(());
7279
7280        for (ix, excerpt) in excerpts.iter().enumerate() {
7281            if ix == 0 {
7282                if excerpt.locator <= Locator::min() {
7283                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
7284                }
7285            } else if excerpt.locator <= excerpts[ix - 1].locator {
7286                panic!("excerpts are out-of-order: {:?}", excerpts);
7287            }
7288        }
7289
7290        for (ix, entry) in excerpt_ids.iter().enumerate() {
7291            if ix == 0 {
7292                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
7293                    panic!("invalid first excerpt id {:?}", entry.id);
7294                }
7295            } else if entry.id <= excerpt_ids[ix - 1].id {
7296                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
7297            }
7298        }
7299
7300        if self.diff_transforms.summary().input != self.excerpts.summary().text {
7301            panic!(
7302                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
7303                self.excerpts.summary().text,
7304                self.diff_transforms.summary().input,
7305                self.diff_transforms.items(()),
7306            );
7307        }
7308
7309        let mut prev_transform: Option<&DiffTransform> = None;
7310        for item in self.diff_transforms.iter() {
7311            if let DiffTransform::BufferContent {
7312                summary,
7313                inserted_hunk_info,
7314            } = item
7315            {
7316                if let Some(DiffTransform::BufferContent {
7317                    inserted_hunk_info: prev_inserted_hunk_info,
7318                    ..
7319                }) = prev_transform
7320                    && *inserted_hunk_info == *prev_inserted_hunk_info
7321                {
7322                    panic!(
7323                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
7324                        self.diff_transforms.items(())
7325                    );
7326                }
7327                if summary.len == MultiBufferOffset(0) && !self.is_empty() {
7328                    panic!("empty buffer content transform");
7329                }
7330            }
7331            prev_transform = Some(item);
7332        }
7333    }
7334}
7335
7336impl<'a, MBD, BD> MultiBufferCursor<'a, MBD, BD>
7337where
7338    MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
7339    BD: TextDimension + AddAssign<<MBD as Sub>::Output>,
7340{
7341    #[instrument(skip_all)]
7342    fn seek(&mut self, position: &MBD) {
7343        let position = OutputDimension(*position);
7344        self.cached_region.take();
7345        self.diff_transforms.seek(&position, Bias::Right);
7346        if self.diff_transforms.item().is_none()
7347            && self.diff_transforms.start().output_dimension == position
7348        {
7349            self.diff_transforms.prev();
7350        }
7351
7352        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension;
7353        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7354            let overshoot = position - self.diff_transforms.start().output_dimension;
7355            excerpt_position += overshoot;
7356        }
7357
7358        self.excerpts.seek(&excerpt_position, Bias::Right);
7359        if self.excerpts.item().is_none() && excerpt_position == *self.excerpts.start() {
7360            self.excerpts.prev();
7361        }
7362    }
7363
7364    fn seek_forward(&mut self, position: &MBD) {
7365        let position = OutputDimension(*position);
7366        self.cached_region.take();
7367        self.diff_transforms.seek_forward(&position, Bias::Right);
7368        if self.diff_transforms.item().is_none()
7369            && self.diff_transforms.start().output_dimension == position
7370        {
7371            self.diff_transforms.prev();
7372        }
7373
7374        let overshoot = position - self.diff_transforms.start().output_dimension;
7375        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension;
7376        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7377            excerpt_position += overshoot;
7378        }
7379
7380        self.excerpts.seek_forward(&excerpt_position, Bias::Right);
7381        if self.excerpts.item().is_none() && excerpt_position == *self.excerpts.start() {
7382            self.excerpts.prev();
7383        }
7384    }
7385
7386    fn next_excerpt(&mut self) {
7387        self.excerpts.next();
7388        self.seek_to_start_of_current_excerpt();
7389    }
7390
7391    fn prev_excerpt(&mut self) {
7392        self.excerpts.prev();
7393        self.seek_to_start_of_current_excerpt();
7394    }
7395
7396    fn seek_to_start_of_current_excerpt(&mut self) {
7397        self.cached_region.take();
7398
7399        if self.diff_transforms.seek(self.excerpts.start(), Bias::Left)
7400            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7401            && self.diff_transforms.next_item().is_some()
7402        {
7403            self.diff_transforms.next();
7404        }
7405    }
7406
7407    fn next_excerpt_forwards(&mut self) {
7408        self.excerpts.next();
7409        self.seek_to_start_of_current_excerpt_forward();
7410    }
7411
7412    fn seek_to_start_of_current_excerpt_forward(&mut self) {
7413        self.cached_region.take();
7414
7415        if self
7416            .diff_transforms
7417            .seek_forward(self.excerpts.start(), Bias::Left)
7418            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7419            && self.diff_transforms.next_item().is_some()
7420        {
7421            self.diff_transforms.next();
7422        }
7423    }
7424
7425    fn next(&mut self) {
7426        self.cached_region.take();
7427        match self
7428            .diff_transforms
7429            .end()
7430            .excerpt_dimension
7431            .cmp(&self.excerpts.end())
7432        {
7433            cmp::Ordering::Less => self.diff_transforms.next(),
7434            cmp::Ordering::Greater => self.excerpts.next(),
7435            cmp::Ordering::Equal => {
7436                self.diff_transforms.next();
7437                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
7438                    || self.diff_transforms.item().is_none()
7439                {
7440                    self.excerpts.next();
7441                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
7442                    self.diff_transforms.item()
7443                    && self
7444                        .excerpts
7445                        .item()
7446                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
7447                {
7448                    self.excerpts.next();
7449                }
7450            }
7451        }
7452    }
7453
7454    fn prev(&mut self) {
7455        self.cached_region.take();
7456        match self
7457            .diff_transforms
7458            .start()
7459            .excerpt_dimension
7460            .cmp(self.excerpts.start())
7461        {
7462            cmp::Ordering::Less => self.excerpts.prev(),
7463            cmp::Ordering::Greater => self.diff_transforms.prev(),
7464            cmp::Ordering::Equal => {
7465                self.diff_transforms.prev();
7466                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7467                    || self.diff_transforms.item().is_none()
7468                {
7469                    self.excerpts.prev();
7470                }
7471            }
7472        }
7473    }
7474
7475    fn region(&self) -> Option<&MultiBufferRegion<'a, MBD, BD>> {
7476        self.cached_region
7477            .get_or_init(|| self.build_region())
7478            .as_ref()
7479    }
7480
7481    fn is_at_start_of_excerpt(&mut self) -> bool {
7482        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
7483            return false;
7484        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7485            return true;
7486        }
7487
7488        self.diff_transforms.prev();
7489        let prev_transform = self.diff_transforms.item();
7490        self.diff_transforms.next();
7491
7492        prev_transform.is_none_or(|next_transform| {
7493            matches!(next_transform, DiffTransform::BufferContent { .. })
7494        })
7495    }
7496
7497    fn is_at_end_of_excerpt(&self) -> bool {
7498        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
7499            return false;
7500        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
7501            || self.diff_transforms.item().is_none()
7502        {
7503            return true;
7504        }
7505
7506        let next_transform = self.diff_transforms.next_item();
7507        next_transform.is_none_or(|next_transform| match next_transform {
7508            DiffTransform::BufferContent { .. } => true,
7509            DiffTransform::DeletedHunk { hunk_info, .. } => self
7510                .excerpts
7511                .item()
7512                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
7513        })
7514    }
7515
7516    fn main_buffer_position(&self) -> Option<BD> {
7517        let excerpt = self.excerpts.item()?;
7518        let buffer = &excerpt.buffer;
7519        let buffer_context_start = excerpt.range.context.start.summary::<BD>(buffer);
7520        let mut buffer_start = buffer_context_start;
7521        let overshoot = self.diff_transforms.end().excerpt_dimension - *self.excerpts.start();
7522        buffer_start += overshoot;
7523        Some(buffer_start)
7524    }
7525
7526    fn build_region(&self) -> Option<MultiBufferRegion<'a, MBD, BD>> {
7527        let excerpt = self.excerpts.item()?;
7528        match self.diff_transforms.item()? {
7529            DiffTransform::DeletedHunk {
7530                buffer_id,
7531                base_text_byte_range,
7532                has_trailing_newline,
7533                hunk_info,
7534                ..
7535            } => {
7536                let diff = self.diffs.get(buffer_id)?;
7537                let buffer = diff.base_text();
7538                let mut rope_cursor = buffer.as_rope().cursor(0);
7539                let buffer_start = rope_cursor.summary::<BD>(base_text_byte_range.start);
7540                let buffer_range_len = rope_cursor.summary::<BD>(base_text_byte_range.end);
7541                let mut buffer_end = buffer_start;
7542                TextDimension::add_assign(&mut buffer_end, &buffer_range_len);
7543                let start = self.diff_transforms.start().output_dimension.0;
7544                let end = self.diff_transforms.end().output_dimension.0;
7545                Some(MultiBufferRegion {
7546                    buffer,
7547                    excerpt,
7548                    has_trailing_newline: *has_trailing_newline,
7549                    is_main_buffer: false,
7550                    diff_hunk_status: Some(DiffHunkStatus::deleted(
7551                        hunk_info.hunk_secondary_status,
7552                    )),
7553                    buffer_range: buffer_start..buffer_end,
7554                    range: start..end,
7555                })
7556            }
7557            DiffTransform::BufferContent {
7558                inserted_hunk_info, ..
7559            } => {
7560                let buffer = &excerpt.buffer;
7561                let buffer_context_start = excerpt.range.context.start.summary::<BD>(buffer);
7562
7563                let mut start = self.diff_transforms.start().output_dimension.0;
7564                let mut buffer_start = buffer_context_start;
7565                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7566                    let overshoot =
7567                        *self.excerpts.start() - self.diff_transforms.start().excerpt_dimension;
7568                    start += overshoot;
7569                } else {
7570                    let overshoot =
7571                        self.diff_transforms.start().excerpt_dimension - *self.excerpts.start();
7572                    buffer_start += overshoot;
7573                }
7574
7575                let mut end;
7576                let mut buffer_end;
7577                let has_trailing_newline;
7578                let transform_end = self.diff_transforms.end();
7579                if transform_end.excerpt_dimension < self.excerpts.end() {
7580                    let overshoot = transform_end.excerpt_dimension - *self.excerpts.start();
7581                    end = transform_end.output_dimension.0;
7582                    buffer_end = buffer_context_start;
7583                    buffer_end += overshoot;
7584                    has_trailing_newline = false;
7585                } else {
7586                    let overshoot =
7587                        self.excerpts.end() - self.diff_transforms.start().excerpt_dimension;
7588                    end = self.diff_transforms.start().output_dimension.0;
7589                    end += overshoot;
7590                    buffer_end = excerpt.range.context.end.summary::<BD>(buffer);
7591                    has_trailing_newline = excerpt.has_trailing_newline;
7592                };
7593
7594                let diff_hunk_status = inserted_hunk_info.map(|info| {
7595                    if info.is_logically_deleted {
7596                        DiffHunkStatus::deleted(info.hunk_secondary_status)
7597                    } else {
7598                        DiffHunkStatus::added(info.hunk_secondary_status)
7599                    }
7600                });
7601
7602                Some(MultiBufferRegion {
7603                    buffer,
7604                    excerpt,
7605                    has_trailing_newline,
7606                    is_main_buffer: true,
7607                    diff_hunk_status,
7608                    buffer_range: buffer_start..buffer_end,
7609                    range: start..end,
7610                })
7611            }
7612        }
7613    }
7614
7615    fn fetch_excerpt_with_range(&self) -> Option<(&'a Excerpt, Range<MBD>)> {
7616        let excerpt = self.excerpts.item()?;
7617        match self.diff_transforms.item()? {
7618            &DiffTransform::DeletedHunk { .. } => {
7619                let start = self.diff_transforms.start().output_dimension.0;
7620                let end = self.diff_transforms.end().output_dimension.0;
7621                Some((excerpt, start..end))
7622            }
7623            DiffTransform::BufferContent { .. } => {
7624                let mut start = self.diff_transforms.start().output_dimension.0;
7625                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7626                    let overshoot =
7627                        *self.excerpts.start() - self.diff_transforms.start().excerpt_dimension;
7628                    start += overshoot;
7629                }
7630
7631                let mut end;
7632                let transform_end = self.diff_transforms.end();
7633                if transform_end.excerpt_dimension < self.excerpts.end() {
7634                    end = transform_end.output_dimension.0;
7635                } else {
7636                    let overshoot =
7637                        self.excerpts.end() - self.diff_transforms.start().excerpt_dimension;
7638                    end = self.diff_transforms.start().output_dimension.0;
7639                    end += overshoot;
7640                };
7641
7642                Some((excerpt, start..end))
7643            }
7644        }
7645    }
7646
7647    fn excerpt(&self) -> Option<&'a Excerpt> {
7648        self.excerpts.item()
7649    }
7650}
7651
7652impl Excerpt {
7653    fn new(
7654        id: ExcerptId,
7655        locator: Locator,
7656        buffer_id: BufferId,
7657        buffer: Arc<BufferSnapshot>,
7658        range: ExcerptRange<text::Anchor>,
7659        has_trailing_newline: bool,
7660    ) -> Self {
7661        Excerpt {
7662            id,
7663            locator,
7664            max_buffer_row: range.context.end.to_point(&buffer).row,
7665            text_summary: buffer
7666                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
7667            buffer_id,
7668            buffer,
7669            range,
7670            has_trailing_newline,
7671        }
7672    }
7673
7674    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
7675        let content_start = self.range.context.start.to_offset(&self.buffer);
7676        let chunks_start = content_start + range.start;
7677        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7678
7679        let has_footer = self.has_trailing_newline
7680            && range.start <= self.text_summary.len
7681            && range.end > self.text_summary.len;
7682
7683        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
7684
7685        ExcerptChunks {
7686            excerpt_id: self.id,
7687            content_chunks,
7688            has_footer,
7689        }
7690    }
7691
7692    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
7693        let content_start = self.range.context.start.to_offset(&self.buffer);
7694        let chunks_start = content_start + range.start;
7695        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7696        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
7697        excerpt_chunks.has_footer = self.has_trailing_newline
7698            && range.start <= self.text_summary.len
7699            && range.end > self.text_summary.len;
7700    }
7701
7702    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
7703        if text_anchor
7704            .cmp(&self.range.context.start, &self.buffer)
7705            .is_lt()
7706        {
7707            self.range.context.start
7708        } else if text_anchor
7709            .cmp(&self.range.context.end, &self.buffer)
7710            .is_gt()
7711        {
7712            self.range.context.end
7713        } else {
7714            text_anchor
7715        }
7716    }
7717
7718    fn contains(&self, anchor: &Anchor) -> bool {
7719        (anchor.text_anchor.buffer_id == None
7720            || anchor.text_anchor.buffer_id == Some(self.buffer_id))
7721            && self
7722                .range
7723                .context
7724                .start
7725                .cmp(&anchor.text_anchor, &self.buffer)
7726                .is_le()
7727            && self
7728                .range
7729                .context
7730                .end
7731                .cmp(&anchor.text_anchor, &self.buffer)
7732                .is_ge()
7733    }
7734
7735    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7736    fn buffer_start_offset(&self) -> BufferOffset {
7737        BufferOffset(self.range.context.start.to_offset(&self.buffer))
7738    }
7739
7740    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7741    fn buffer_end_offset(&self) -> BufferOffset {
7742        self.buffer_start_offset() + self.text_summary.len
7743    }
7744}
7745
7746impl<'a> MultiBufferExcerpt<'a> {
7747    pub fn id(&self) -> ExcerptId {
7748        self.excerpt.id
7749    }
7750
7751    pub fn buffer_id(&self) -> BufferId {
7752        self.excerpt.buffer_id
7753    }
7754
7755    pub fn start_anchor(&self) -> Anchor {
7756        Anchor::in_buffer(self.excerpt.id, self.excerpt.range.context.start)
7757    }
7758
7759    pub fn end_anchor(&self) -> Anchor {
7760        Anchor::in_buffer(self.excerpt.id, self.excerpt.range.context.end)
7761    }
7762
7763    pub fn buffer(&self) -> &'a BufferSnapshot {
7764        &self.excerpt.buffer
7765    }
7766
7767    pub fn buffer_range(&self) -> Range<BufferOffset> {
7768        self.buffer_offset
7769            ..BufferOffset(
7770                self.excerpt
7771                    .range
7772                    .context
7773                    .end
7774                    .to_offset(&self.excerpt.buffer.text),
7775            )
7776    }
7777
7778    pub fn start_offset(&self) -> MultiBufferOffset {
7779        self.offset
7780    }
7781
7782    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7783    pub fn map_offset_to_buffer(&mut self, offset: MultiBufferOffset) -> BufferOffset {
7784        self.map_range_to_buffer(offset..offset).start
7785    }
7786
7787    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7788    pub fn map_range_to_buffer(&mut self, range: Range<MultiBufferOffset>) -> Range<BufferOffset> {
7789        self.diff_transforms
7790            .seek(&OutputDimension(range.start), Bias::Right);
7791        let start = self.map_offset_to_buffer_internal(range.start);
7792        let end = if range.end > range.start {
7793            self.diff_transforms
7794                .seek_forward(&OutputDimension(range.end), Bias::Right);
7795            self.map_offset_to_buffer_internal(range.end)
7796        } else {
7797            start
7798        };
7799        start..end
7800    }
7801
7802    fn map_offset_to_buffer_internal(&self, offset: MultiBufferOffset) -> BufferOffset {
7803        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension;
7804        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7805            excerpt_offset += offset - self.diff_transforms.start().output_dimension.0;
7806        };
7807        let offset_in_excerpt = excerpt_offset.saturating_sub(self.excerpt_offset);
7808        self.buffer_offset + offset_in_excerpt
7809    }
7810
7811    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7812    pub fn map_offset_from_buffer(&mut self, buffer_offset: BufferOffset) -> MultiBufferOffset {
7813        self.map_range_from_buffer(buffer_offset..buffer_offset)
7814            .start
7815    }
7816
7817    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7818    pub fn map_range_from_buffer(
7819        &mut self,
7820        buffer_range: Range<BufferOffset>,
7821    ) -> Range<MultiBufferOffset> {
7822        if buffer_range.start < self.buffer_offset {
7823            log::warn!(
7824                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7825            );
7826            return self.offset..self.offset;
7827        }
7828        let overshoot = buffer_range.start - self.buffer_offset;
7829        let excerpt_offset = self.excerpt_offset + overshoot;
7830        let excerpt_seek_dim = excerpt_offset;
7831        self.diff_transforms.seek(&excerpt_seek_dim, Bias::Right);
7832        if self.diff_transforms.start().excerpt_dimension > excerpt_offset {
7833            log::warn!(
7834                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7835            );
7836            return self.offset..self.offset;
7837        }
7838        let overshoot = excerpt_offset - self.diff_transforms.start().excerpt_dimension;
7839        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7840
7841        let end = if buffer_range.start < buffer_range.end {
7842            let overshoot = buffer_range.end - self.buffer_offset;
7843            let excerpt_offset = self.excerpt_offset + overshoot;
7844            let excerpt_seek_dim = excerpt_offset;
7845            self.diff_transforms
7846                .seek_forward(&excerpt_seek_dim, Bias::Right);
7847            let overshoot = excerpt_offset - self.diff_transforms.start().excerpt_dimension;
7848            // todo(lw): Clamp end to the excerpt boundaries
7849            self.diff_transforms.start().output_dimension.0 + overshoot
7850        } else {
7851            start
7852        };
7853
7854        start..end
7855    }
7856
7857    /// Returns true if the entirety of the given range is in the buffer's excerpt
7858    pub fn contains_buffer_range(&self, range: Range<BufferOffset>) -> bool {
7859        range.start >= self.excerpt.buffer_start_offset()
7860            && range.end <= self.excerpt.buffer_end_offset()
7861    }
7862
7863    /// Returns true if any part of the given range is in the buffer's excerpt
7864    pub fn contains_partial_buffer_range(&self, range: Range<BufferOffset>) -> bool {
7865        range.start <= self.excerpt.buffer_end_offset()
7866            && range.end >= self.excerpt.buffer_start_offset()
7867    }
7868
7869    pub fn max_buffer_row(&self) -> u32 {
7870        self.excerpt.max_buffer_row
7871    }
7872}
7873
7874impl ExcerptId {
7875    pub fn min() -> Self {
7876        Self(0)
7877    }
7878
7879    pub fn max() -> Self {
7880        Self(u32::MAX)
7881    }
7882
7883    pub fn to_proto(self) -> u64 {
7884        self.0 as _
7885    }
7886
7887    pub fn from_proto(proto: u64) -> Self {
7888        Self(proto as _)
7889    }
7890
7891    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7892        let a = snapshot.excerpt_locator_for_id(*self);
7893        let b = snapshot.excerpt_locator_for_id(*other);
7894        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7895    }
7896}
7897
7898impl From<ExcerptId> for usize {
7899    fn from(val: ExcerptId) -> Self {
7900        val.0 as usize
7901    }
7902}
7903
7904impl fmt::Debug for Excerpt {
7905    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7906        f.debug_struct("Excerpt")
7907            .field("id", &self.id)
7908            .field("locator", &self.locator)
7909            .field("buffer_id", &self.buffer_id)
7910            .field("range", &self.range)
7911            .field("text_summary", &self.text_summary)
7912            .field("has_trailing_newline", &self.has_trailing_newline)
7913            .finish()
7914    }
7915}
7916
7917impl sum_tree::Item for Excerpt {
7918    type Summary = ExcerptSummary;
7919
7920    fn summary(&self, _cx: ()) -> Self::Summary {
7921        let mut text = self.text_summary;
7922        if self.has_trailing_newline {
7923            text += TextSummary::from("\n");
7924        }
7925        ExcerptSummary {
7926            excerpt_id: self.id,
7927            excerpt_locator: self.locator.clone(),
7928            widest_line_number: self.max_buffer_row,
7929            text: text.into(),
7930            count: 1,
7931        }
7932    }
7933}
7934
7935impl sum_tree::Item for ExcerptIdMapping {
7936    type Summary = ExcerptId;
7937
7938    fn summary(&self, _cx: ()) -> Self::Summary {
7939        self.id
7940    }
7941}
7942
7943impl sum_tree::KeyedItem for ExcerptIdMapping {
7944    type Key = ExcerptId;
7945
7946    fn key(&self) -> Self::Key {
7947        self.id
7948    }
7949}
7950
7951impl DiffTransform {
7952    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7953        match self {
7954            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7955            DiffTransform::BufferContent {
7956                inserted_hunk_info, ..
7957            } => *inserted_hunk_info,
7958        }
7959    }
7960}
7961
7962impl sum_tree::Item for DiffTransform {
7963    type Summary = DiffTransformSummary;
7964
7965    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7966        match self {
7967            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7968                input: *summary,
7969                output: *summary,
7970            },
7971            &DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7972                input: MBTextSummary::default(),
7973                output: summary.into(),
7974            },
7975        }
7976    }
7977}
7978
7979impl DiffTransformSummary {
7980    fn excerpt_len(&self) -> ExcerptOffset {
7981        ExcerptDimension(self.input.len)
7982    }
7983}
7984
7985impl sum_tree::ContextLessSummary for DiffTransformSummary {
7986    fn zero() -> Self {
7987        DiffTransformSummary {
7988            input: MBTextSummary::default(),
7989            output: MBTextSummary::default(),
7990        }
7991    }
7992
7993    fn add_summary(&mut self, other: &Self) {
7994        self.input += other.input;
7995        self.output += other.output;
7996    }
7997}
7998
7999impl sum_tree::ContextLessSummary for ExcerptId {
8000    fn zero() -> Self {
8001        Self(0)
8002    }
8003
8004    fn add_summary(&mut self, summary: &Self) {
8005        *self = cmp::max(*self, *summary);
8006    }
8007}
8008
8009impl sum_tree::ContextLessSummary for ExcerptSummary {
8010    fn zero() -> Self {
8011        Self::default()
8012    }
8013
8014    fn add_summary(&mut self, summary: &Self) {
8015        debug_assert!(
8016            summary.excerpt_locator > self.excerpt_locator
8017                || self.excerpt_locator == Locator::min(),
8018            "Excerpt locators must be in ascending order: {:?} > {:?}",
8019            summary.excerpt_locator,
8020            self.excerpt_locator
8021        );
8022        self.excerpt_locator = summary.excerpt_locator.clone();
8023        self.text += summary.text;
8024        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
8025        self.count += summary.count;
8026    }
8027}
8028
8029impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
8030    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
8031        Ord::cmp(&Some(self), cursor_location)
8032    }
8033}
8034
8035impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
8036    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
8037        Ord::cmp(self, &cursor_location.excerpt_locator)
8038    }
8039}
8040
8041impl<'a, MBD> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptDimension<MBD>
8042where
8043    MBD: MultiBufferDimension + Default,
8044{
8045    fn zero(_: ()) -> Self {
8046        ExcerptDimension(MBD::default())
8047    }
8048
8049    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8050        MultiBufferDimension::add_mb_text_summary(&mut self.0, &summary.text)
8051    }
8052}
8053
8054impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
8055    fn zero(_cx: ()) -> Self {
8056        Default::default()
8057    }
8058
8059    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8060        *self = Some(&summary.excerpt_locator);
8061    }
8062}
8063
8064impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
8065    fn zero(_cx: ()) -> Self {
8066        Default::default()
8067    }
8068
8069    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8070        *self = Some(summary.excerpt_id);
8071    }
8072}
8073
8074#[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
8075struct OutputDimension<T>(T);
8076
8077impl<T: PartialEq> PartialEq<T> for OutputDimension<T> {
8078    fn eq(&self, other: &T) -> bool {
8079        self.0 == *other
8080    }
8081}
8082
8083impl<T: PartialOrd> PartialOrd<T> for OutputDimension<T> {
8084    fn partial_cmp(&self, other: &T) -> Option<cmp::Ordering> {
8085        self.0.partial_cmp(other)
8086    }
8087}
8088
8089impl<R, T, U> ops::Sub<OutputDimension<U>> for OutputDimension<T>
8090where
8091    T: ops::Sub<U, Output = R>,
8092{
8093    type Output = R;
8094
8095    fn sub(self, other: OutputDimension<U>) -> Self::Output {
8096        self.0 - other.0
8097    }
8098}
8099
8100impl<R, T, U> ops::Add<U> for OutputDimension<T>
8101where
8102    T: ops::Add<U, Output = R>,
8103{
8104    type Output = OutputDimension<R>;
8105
8106    fn add(self, other: U) -> Self::Output {
8107        OutputDimension(self.0 + other)
8108    }
8109}
8110
8111impl<T, U> AddAssign<U> for OutputDimension<T>
8112where
8113    T: AddAssign<U>,
8114{
8115    fn add_assign(&mut self, other: U) {
8116        self.0 += other;
8117    }
8118}
8119
8120impl<T, U> SubAssign<U> for OutputDimension<T>
8121where
8122    T: SubAssign<U>,
8123{
8124    fn sub_assign(&mut self, other: U) {
8125        self.0 -= other;
8126    }
8127}
8128
8129#[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
8130struct ExcerptDimension<T>(T);
8131
8132impl<T: PartialEq> PartialEq<T> for ExcerptDimension<T> {
8133    fn eq(&self, other: &T) -> bool {
8134        self.0 == *other
8135    }
8136}
8137
8138impl<T: PartialOrd> PartialOrd<T> for ExcerptDimension<T> {
8139    fn partial_cmp(&self, other: &T) -> Option<cmp::Ordering> {
8140        self.0.partial_cmp(other)
8141    }
8142}
8143
8144impl ExcerptOffset {
8145    fn saturating_sub(self, other: ExcerptOffset) -> usize {
8146        self.0.saturating_sub(other.0)
8147    }
8148}
8149
8150impl<R, T, U> ops::Sub<ExcerptDimension<U>> for ExcerptDimension<T>
8151where
8152    T: ops::Sub<U, Output = R>,
8153{
8154    type Output = R;
8155
8156    fn sub(self, other: ExcerptDimension<U>) -> Self::Output {
8157        self.0 - other.0
8158    }
8159}
8160
8161impl<R, T, U> ops::Add<U> for ExcerptDimension<T>
8162where
8163    T: ops::Add<U, Output = R>,
8164{
8165    type Output = ExcerptDimension<R>;
8166
8167    fn add(self, other: U) -> Self::Output {
8168        ExcerptDimension(self.0 + other)
8169    }
8170}
8171
8172impl<T, U> AddAssign<U> for ExcerptDimension<T>
8173where
8174    T: AddAssign<U>,
8175{
8176    fn add_assign(&mut self, other: U) {
8177        self.0 += other;
8178    }
8179}
8180
8181impl<T, U> SubAssign<U> for ExcerptDimension<T>
8182where
8183    T: SubAssign<U>,
8184{
8185    fn sub_assign(&mut self, other: U) {
8186        self.0 -= other;
8187    }
8188}
8189
8190impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for MultiBufferOffset {
8191    fn zero(_: ()) -> Self {
8192        MultiBufferOffset::ZERO
8193    }
8194
8195    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8196        *self += summary.output.len;
8197    }
8198}
8199
8200impl<MBD> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
8201    for ExcerptDimension<MBD>
8202where
8203    MBD: MultiBufferDimension + Ord,
8204{
8205    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
8206        Ord::cmp(&self.0, &MBD::from_summary(&cursor_location.input))
8207    }
8208}
8209
8210impl<'a, MBD> sum_tree::SeekTarget<'a, DiffTransformSummary, DiffTransforms<MBD>>
8211    for ExcerptDimension<MBD>
8212where
8213    MBD: MultiBufferDimension + Ord,
8214{
8215    fn cmp(&self, cursor_location: &DiffTransforms<MBD>, _: ()) -> cmp::Ordering {
8216        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
8217    }
8218}
8219
8220impl<'a, MBD: MultiBufferDimension> sum_tree::Dimension<'a, DiffTransformSummary>
8221    for ExcerptDimension<MBD>
8222{
8223    fn zero(_: ()) -> Self {
8224        ExcerptDimension(MBD::default())
8225    }
8226
8227    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8228        self.0.add_mb_text_summary(&summary.input)
8229    }
8230}
8231
8232impl<'a, MBD> sum_tree::SeekTarget<'a, DiffTransformSummary, DiffTransforms<MBD>>
8233    for OutputDimension<MBD>
8234where
8235    MBD: MultiBufferDimension + Ord,
8236{
8237    fn cmp(&self, cursor_location: &DiffTransforms<MBD>, _: ()) -> cmp::Ordering {
8238        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
8239    }
8240}
8241
8242impl<'a, MBD: MultiBufferDimension> sum_tree::Dimension<'a, DiffTransformSummary>
8243    for OutputDimension<MBD>
8244{
8245    fn zero(_: ()) -> Self {
8246        OutputDimension(MBD::default())
8247    }
8248
8249    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8250        self.0.add_mb_text_summary(&summary.output)
8251    }
8252}
8253
8254impl MultiBufferRows<'_> {
8255    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
8256        self.point = Point::new(row, 0);
8257        self.cursor.seek(&self.point);
8258    }
8259}
8260
8261impl Iterator for MultiBufferRows<'_> {
8262    type Item = RowInfo;
8263
8264    fn next(&mut self) -> Option<Self::Item> {
8265        if self.is_empty && self.point.row == 0 {
8266            self.point += Point::new(1, 0);
8267            return Some(RowInfo {
8268                buffer_id: None,
8269                buffer_row: Some(0),
8270                multibuffer_row: Some(MultiBufferRow(0)),
8271                diff_status: None,
8272                expand_info: None,
8273                wrapped_buffer_row: None,
8274            });
8275        }
8276
8277        let mut region = self.cursor.region()?.clone();
8278        while self.point >= region.range.end {
8279            self.cursor.next();
8280            if let Some(next_region) = self.cursor.region() {
8281                region = next_region.clone();
8282            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
8283                let multibuffer_row = MultiBufferRow(self.point.row);
8284                let last_excerpt = self
8285                    .cursor
8286                    .excerpts
8287                    .item()
8288                    .or(self.cursor.excerpts.prev_item())?;
8289                let last_row = last_excerpt
8290                    .range
8291                    .context
8292                    .end
8293                    .to_point(&last_excerpt.buffer)
8294                    .row;
8295
8296                let first_row = last_excerpt
8297                    .range
8298                    .context
8299                    .start
8300                    .to_point(&last_excerpt.buffer)
8301                    .row;
8302
8303                let expand_info = if self.is_singleton {
8304                    None
8305                } else {
8306                    let needs_expand_up = first_row == last_row
8307                        && last_row > 0
8308                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
8309                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
8310
8311                    if needs_expand_up && needs_expand_down {
8312                        Some(ExpandExcerptDirection::UpAndDown)
8313                    } else if needs_expand_up {
8314                        Some(ExpandExcerptDirection::Up)
8315                    } else if needs_expand_down {
8316                        Some(ExpandExcerptDirection::Down)
8317                    } else {
8318                        None
8319                    }
8320                    .map(|direction| ExpandInfo {
8321                        direction,
8322                        excerpt_id: last_excerpt.id,
8323                    })
8324                };
8325                self.point += Point::new(1, 0);
8326                return Some(RowInfo {
8327                    buffer_id: Some(last_excerpt.buffer_id),
8328                    buffer_row: Some(last_row),
8329                    multibuffer_row: Some(multibuffer_row),
8330                    diff_status: None,
8331                    wrapped_buffer_row: None,
8332                    expand_info,
8333                });
8334            } else {
8335                return None;
8336            };
8337        }
8338
8339        let overshoot = self.point - region.range.start;
8340        let buffer_point = region.buffer_range.start + overshoot;
8341        let expand_info = if self.is_singleton {
8342            None
8343        } else {
8344            let needs_expand_up = self.point.row == region.range.start.row
8345                && self.cursor.is_at_start_of_excerpt()
8346                && buffer_point.row > 0;
8347            let needs_expand_down = (region.excerpt.has_trailing_newline
8348                && self.point.row + 1 == region.range.end.row
8349                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
8350                && self.cursor.is_at_end_of_excerpt()
8351                && buffer_point.row < region.buffer.max_point().row;
8352
8353            if needs_expand_up && needs_expand_down {
8354                Some(ExpandExcerptDirection::UpAndDown)
8355            } else if needs_expand_up {
8356                Some(ExpandExcerptDirection::Up)
8357            } else if needs_expand_down {
8358                Some(ExpandExcerptDirection::Down)
8359            } else {
8360                None
8361            }
8362            .map(|direction| ExpandInfo {
8363                direction,
8364                excerpt_id: region.excerpt.id,
8365            })
8366        };
8367
8368        let result = Some(RowInfo {
8369            buffer_id: Some(region.buffer.remote_id()),
8370            buffer_row: Some(buffer_point.row),
8371            multibuffer_row: Some(MultiBufferRow(self.point.row)),
8372            diff_status: region
8373                .diff_hunk_status
8374                .filter(|_| self.point < region.range.end),
8375            expand_info,
8376            wrapped_buffer_row: None,
8377        });
8378        self.point += Point::new(1, 0);
8379        result
8380    }
8381}
8382
8383impl<'a> MultiBufferChunks<'a> {
8384    pub fn offset(&self) -> MultiBufferOffset {
8385        self.range.start
8386    }
8387
8388    pub fn seek(&mut self, range: Range<MultiBufferOffset>) {
8389        self.diff_transforms.seek(&range.end, Bias::Right);
8390        let mut excerpt_end = self.diff_transforms.start().1;
8391        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
8392            let overshoot = range.end - self.diff_transforms.start().0;
8393            excerpt_end += overshoot;
8394        }
8395
8396        self.diff_transforms.seek(&range.start, Bias::Right);
8397        let mut excerpt_start = self.diff_transforms.start().1;
8398        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
8399            let overshoot = range.start - self.diff_transforms.start().0;
8400            excerpt_start += overshoot;
8401        }
8402
8403        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
8404        self.buffer_chunk.take();
8405        self.range = range;
8406    }
8407
8408    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
8409        self.excerpt_offset_range = new_range.clone();
8410        self.excerpts.seek(&new_range.start, Bias::Right);
8411        if let Some(excerpt) = self.excerpts.item() {
8412            let excerpt_start = *self.excerpts.start();
8413            if let Some(excerpt_chunks) = self
8414                .excerpt_chunks
8415                .as_mut()
8416                .filter(|chunks| excerpt.id == chunks.excerpt_id)
8417            {
8418                excerpt.seek_chunks(
8419                    excerpt_chunks,
8420                    (self.excerpt_offset_range.start - excerpt_start)
8421                        ..(self.excerpt_offset_range.end - excerpt_start),
8422                );
8423            } else {
8424                self.excerpt_chunks = Some(excerpt.chunks_in_range(
8425                    (self.excerpt_offset_range.start - excerpt_start)
8426                        ..(self.excerpt_offset_range.end - excerpt_start),
8427                    self.language_aware,
8428                ));
8429            }
8430        } else {
8431            self.excerpt_chunks = None;
8432        }
8433    }
8434
8435    #[ztracing::instrument(skip_all)]
8436    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
8437        loop {
8438            if self.excerpt_offset_range.is_empty() {
8439                return None;
8440            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
8441                self.excerpt_offset_range.start += chunk.text.len();
8442                return Some(chunk);
8443            } else {
8444                self.excerpts.next();
8445                let excerpt = self.excerpts.item()?;
8446                self.excerpt_chunks = Some(excerpt.chunks_in_range(
8447                    0..(self.excerpt_offset_range.end - *self.excerpts.start()),
8448                    self.language_aware,
8449                ));
8450            }
8451        }
8452    }
8453}
8454
8455impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
8456    type Item = &'a str;
8457
8458    fn next(&mut self) -> Option<Self::Item> {
8459        let mut region = self.cursor.region()?;
8460        if self.offset == region.range.start {
8461            self.cursor.prev();
8462            region = self.cursor.region()?;
8463            let start_overshoot = self.start.saturating_sub(region.range.start);
8464            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
8465                region.buffer_range.start + start_overshoot..region.buffer_range.end,
8466            ));
8467        }
8468
8469        if self.offset == region.range.end && region.has_trailing_newline {
8470            self.offset -= 1;
8471            Some("\n")
8472        } else {
8473            let chunk = self.current_chunks.as_mut().unwrap().next()?;
8474            self.offset -= chunk.len();
8475            Some(chunk)
8476        }
8477    }
8478}
8479
8480impl<'a> Iterator for MultiBufferChunks<'a> {
8481    type Item = Chunk<'a>;
8482
8483    #[ztracing::instrument(skip_all)]
8484    fn next(&mut self) -> Option<Chunk<'a>> {
8485        if self.range.start >= self.range.end {
8486            return None;
8487        }
8488        if self.range.start == self.diff_transforms.end().0 {
8489            self.diff_transforms.next();
8490        }
8491
8492        let diff_transform_start = self.diff_transforms.start().0;
8493        let diff_transform_end = self.diff_transforms.end().0;
8494        debug_assert!(
8495            self.range.start < diff_transform_end,
8496            "{:?} < {:?} of ({1:?}..{2:?})",
8497            self.range.start,
8498            diff_transform_end,
8499            diff_transform_start
8500        );
8501
8502        let diff_transform = self.diff_transforms.item()?;
8503        match diff_transform {
8504            DiffTransform::BufferContent { .. } => {
8505                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
8506                    chunk
8507                } else {
8508                    let chunk = self.next_excerpt_chunk().unwrap();
8509                    self.buffer_chunk.insert(chunk)
8510                };
8511
8512                let chunk_end = self.range.start + chunk.text.len();
8513                let diff_transform_end = diff_transform_end.min(self.range.end);
8514
8515                if diff_transform_end < chunk_end {
8516                    let split_idx = diff_transform_end - self.range.start;
8517                    let (before, after) = chunk.text.split_at(split_idx);
8518                    self.range.start = diff_transform_end;
8519                    let mask = 1u128.unbounded_shl(split_idx as u32).wrapping_sub(1);
8520                    let chars = chunk.chars & mask;
8521                    let tabs = chunk.tabs & mask;
8522                    let newlines = chunk.newlines & mask;
8523
8524                    chunk.text = after;
8525                    chunk.chars = chunk.chars >> split_idx;
8526                    chunk.tabs = chunk.tabs >> split_idx;
8527                    chunk.newlines = chunk.newlines >> split_idx;
8528
8529                    Some(Chunk {
8530                        text: before,
8531                        chars,
8532                        tabs,
8533                        newlines,
8534                        ..chunk.clone()
8535                    })
8536                } else {
8537                    self.range.start = chunk_end;
8538                    self.buffer_chunk.take()
8539                }
8540            }
8541            DiffTransform::DeletedHunk {
8542                buffer_id,
8543                base_text_byte_range,
8544                has_trailing_newline,
8545                ..
8546            } => {
8547                let base_text_start =
8548                    base_text_byte_range.start + (self.range.start - diff_transform_start);
8549                let base_text_end =
8550                    base_text_byte_range.start + (self.range.end - diff_transform_start);
8551                let base_text_end = base_text_end.min(base_text_byte_range.end);
8552
8553                let mut chunks = if let Some((_, mut chunks)) = self
8554                    .diff_base_chunks
8555                    .take()
8556                    .filter(|(id, _)| id == buffer_id)
8557                {
8558                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
8559                    {
8560                        chunks.seek(base_text_start..base_text_end);
8561                    }
8562                    chunks
8563                } else {
8564                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
8565                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
8566                };
8567
8568                let chunk = if let Some(chunk) = chunks.next() {
8569                    self.range.start += chunk.text.len();
8570                    self.diff_base_chunks = Some((*buffer_id, chunks));
8571                    chunk
8572                } else {
8573                    debug_assert!(has_trailing_newline);
8574                    self.range.start += "\n".len();
8575                    Chunk {
8576                        text: "\n",
8577                        chars: 1u128,
8578                        newlines: 1u128,
8579                        ..Default::default()
8580                    }
8581                };
8582                Some(chunk)
8583            }
8584        }
8585    }
8586}
8587
8588impl MultiBufferBytes<'_> {
8589    fn consume(&mut self, len: usize) {
8590        self.range.start += len;
8591        self.chunk = &self.chunk[len..];
8592
8593        if !self.range.is_empty() && self.chunk.is_empty() {
8594            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
8595                self.chunk = chunk;
8596            } else if self.has_trailing_newline {
8597                self.has_trailing_newline = false;
8598                self.chunk = b"\n";
8599            } else {
8600                self.cursor.next();
8601                if let Some(region) = self.cursor.region() {
8602                    let mut excerpt_bytes = region.buffer.bytes_in_range(
8603                        region.buffer_range.start
8604                            ..(region.buffer_range.start + (self.range.end - region.range.start))
8605                                .min(region.buffer_range.end),
8606                    );
8607                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
8608                    self.excerpt_bytes = Some(excerpt_bytes);
8609                    self.has_trailing_newline =
8610                        region.has_trailing_newline && self.range.end >= region.range.end;
8611                    if self.chunk.is_empty() && self.has_trailing_newline {
8612                        self.has_trailing_newline = false;
8613                        self.chunk = b"\n";
8614                    }
8615                }
8616            }
8617        }
8618    }
8619}
8620
8621impl<'a> Iterator for MultiBufferBytes<'a> {
8622    type Item = &'a [u8];
8623
8624    fn next(&mut self) -> Option<Self::Item> {
8625        let chunk = self.chunk;
8626        if chunk.is_empty() {
8627            None
8628        } else {
8629            self.consume(chunk.len());
8630            Some(chunk)
8631        }
8632    }
8633}
8634
8635impl io::Read for MultiBufferBytes<'_> {
8636    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
8637        let len = cmp::min(buf.len(), self.chunk.len());
8638        buf[..len].copy_from_slice(&self.chunk[..len]);
8639        if len > 0 {
8640            self.consume(len);
8641        }
8642        Ok(len)
8643    }
8644}
8645
8646impl io::Read for ReversedMultiBufferBytes<'_> {
8647    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
8648        let len = cmp::min(buf.len(), self.chunk.len());
8649        buf[..len].copy_from_slice(&self.chunk[..len]);
8650        buf[..len].reverse();
8651        if len > 0 {
8652            self.range.end -= len;
8653            self.chunk = &self.chunk[..self.chunk.len() - len];
8654            if !self.range.is_empty()
8655                && self.chunk.is_empty()
8656                && let Some(chunk) = self.chunks.next()
8657            {
8658                self.chunk = chunk.as_bytes();
8659            }
8660        }
8661        Ok(len)
8662    }
8663}
8664
8665impl<'a> Iterator for ExcerptChunks<'a> {
8666    type Item = Chunk<'a>;
8667
8668    fn next(&mut self) -> Option<Self::Item> {
8669        if let Some(chunk) = self.content_chunks.next() {
8670            return Some(chunk);
8671        }
8672
8673        if self.has_footer {
8674            let text = "\n";
8675            let chars = 0b1;
8676            let newlines = 0b1;
8677            self.has_footer = false;
8678            return Some(Chunk {
8679                text,
8680                chars,
8681                newlines,
8682                ..Default::default()
8683            });
8684        }
8685
8686        None
8687    }
8688}
8689
8690impl ToOffset for Point {
8691    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8692        snapshot.point_to_offset(*self)
8693    }
8694    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8695        snapshot.point_to_offset_utf16(*self)
8696    }
8697}
8698
8699impl ToOffset for MultiBufferOffset {
8700    #[track_caller]
8701    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8702        assert!(
8703            *self <= snapshot.len(),
8704            "offset {} is greater than the snapshot.len() {}",
8705            self.0,
8706            snapshot.len().0,
8707        );
8708        *self
8709    }
8710    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8711        snapshot.offset_to_offset_utf16(*self)
8712    }
8713}
8714
8715impl ToOffset for MultiBufferOffsetUtf16 {
8716    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8717        snapshot.offset_utf16_to_offset(*self)
8718    }
8719
8720    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8721        *self
8722    }
8723}
8724
8725impl ToOffset for PointUtf16 {
8726    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8727        snapshot.point_utf16_to_offset(*self)
8728    }
8729    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8730        snapshot.point_utf16_to_offset_utf16(*self)
8731    }
8732}
8733
8734impl ToPoint for MultiBufferOffset {
8735    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
8736        snapshot.offset_to_point(*self)
8737    }
8738    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
8739        snapshot.offset_to_point_utf16(*self)
8740    }
8741}
8742
8743impl ToPoint for Point {
8744    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
8745        *self
8746    }
8747    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
8748        snapshot.point_to_point_utf16(*self)
8749    }
8750}
8751
8752impl ToPoint for PointUtf16 {
8753    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
8754        snapshot.point_utf16_to_point(*self)
8755    }
8756    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
8757        *self
8758    }
8759}
8760
8761impl From<ExcerptId> for EntityId {
8762    fn from(id: ExcerptId) -> Self {
8763        EntityId::from(id.0 as u64)
8764    }
8765}
8766
8767#[cfg(debug_assertions)]
8768pub mod debug {
8769    use super::*;
8770
8771    pub trait ToMultiBufferDebugRanges {
8772        fn to_multi_buffer_debug_ranges(
8773            &self,
8774            snapshot: &MultiBufferSnapshot,
8775        ) -> Vec<Range<MultiBufferOffset>>;
8776    }
8777
8778    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
8779        fn to_multi_buffer_debug_ranges(
8780            &self,
8781            snapshot: &MultiBufferSnapshot,
8782        ) -> Vec<Range<MultiBufferOffset>> {
8783            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
8784        }
8785    }
8786
8787    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
8788        fn to_multi_buffer_debug_ranges(
8789            &self,
8790            snapshot: &MultiBufferSnapshot,
8791        ) -> Vec<Range<MultiBufferOffset>> {
8792            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
8793                .to_multi_buffer_debug_ranges(snapshot)
8794        }
8795    }
8796
8797    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
8798        fn to_multi_buffer_debug_ranges(
8799            &self,
8800            snapshot: &MultiBufferSnapshot,
8801        ) -> Vec<Range<MultiBufferOffset>> {
8802            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8803        }
8804    }
8805
8806    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8807        fn to_multi_buffer_debug_ranges(
8808            &self,
8809            snapshot: &MultiBufferSnapshot,
8810        ) -> Vec<Range<MultiBufferOffset>> {
8811            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8812        }
8813    }
8814
8815    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8816        fn to_multi_buffer_debug_ranges(
8817            &self,
8818            snapshot: &MultiBufferSnapshot,
8819        ) -> Vec<Range<MultiBufferOffset>> {
8820            self.iter()
8821                .map(|item| {
8822                    let offset = item.to_offset(snapshot);
8823                    offset..offset
8824                })
8825                .collect()
8826        }
8827    }
8828
8829    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8830        fn to_multi_buffer_debug_ranges(
8831            &self,
8832            snapshot: &MultiBufferSnapshot,
8833        ) -> Vec<Range<MultiBufferOffset>> {
8834            self.iter()
8835                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8836                .collect()
8837        }
8838    }
8839}