1mod anchor;
   2#[cfg(test)]
   3mod multi_buffer_tests;
   4mod position;
   5
   6pub use anchor::{Anchor, AnchorRangeExt, Offset};
   7pub use position::{TypedOffset, TypedPoint, TypedRow};
   8
   9use anyhow::{Result, anyhow};
  10use buffer_diff::{
  11    BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffHunkSecondaryStatus, DiffHunkStatus,
  12    DiffHunkStatusKind,
  13};
  14use clock::ReplicaId;
  15use collections::{BTreeMap, Bound, HashMap, HashSet};
  16use gpui::{App, AppContext as _, Context, Entity, EntityId, EventEmitter, Task};
  17use itertools::Itertools;
  18use language::{
  19    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharClassifier,
  20    CharKind, Chunk, CursorShape, DiagnosticEntry, DiskState, File, IndentSize, Language,
  21    LanguageScope, OffsetRangeExt, OffsetUtf16, Outline, OutlineItem, Point, PointUtf16, Selection,
  22    TextDimension, TextObject, ToOffset as _, ToPoint as _, TransactionId, TreeSitterOptions,
  23    Unclipped,
  24    language_settings::{IndentGuideSettings, LanguageSettings, language_settings},
  25};
  26
  27use rope::DimensionPair;
  28use smallvec::SmallVec;
  29use smol::future::yield_now;
  30use std::{
  31    any::type_name,
  32    borrow::Cow,
  33    cell::{Cell, Ref, RefCell},
  34    cmp, fmt,
  35    future::Future,
  36    io,
  37    iter::{self, FromIterator},
  38    mem,
  39    ops::{Range, RangeBounds, Sub},
  40    path::{Path, PathBuf},
  41    rc::Rc,
  42    str,
  43    sync::Arc,
  44    time::{Duration, Instant},
  45};
  46use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, Summary, TreeMap};
  47use text::{
  48    BufferId, Edit, LineIndent, TextSummary,
  49    locator::Locator,
  50    subscription::{Subscription, Topic},
  51};
  52use theme::SyntaxTheme;
  53use util::post_inc;
  54
  55const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  56
  57#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  58pub struct ExcerptId(usize);
  59
  60/// One or more [`Buffers`](Buffer) being edited in a single view.
  61///
  62/// See <https://zed.dev/features#multi-buffers>
  63pub struct MultiBuffer {
  64    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  65    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  66    snapshot: RefCell<MultiBufferSnapshot>,
  67    /// Contains the state of the buffers being edited
  68    buffers: RefCell<HashMap<BufferId, BufferState>>,
  69    // only used by consumers using `set_excerpts_for_buffer`
  70    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  71    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  72    diffs: HashMap<BufferId, DiffState>,
  73    // all_diff_hunks_expanded: bool,
  74    subscriptions: Topic,
  75    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  76    singleton: bool,
  77    history: History,
  78    title: Option<String>,
  79    capability: Capability,
  80    buffer_changed_since_sync: Rc<Cell<bool>>,
  81}
  82
  83#[derive(Clone, Debug, PartialEq, Eq)]
  84pub enum MultiOrSingleBufferOffsetRange {
  85    Single(Range<usize>),
  86    Multi(Range<usize>),
  87}
  88
  89#[derive(Clone, Debug, PartialEq, Eq)]
  90pub enum Event {
  91    ExcerptsAdded {
  92        buffer: Entity<Buffer>,
  93        predecessor: ExcerptId,
  94        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  95    },
  96    ExcerptsRemoved {
  97        ids: Vec<ExcerptId>,
  98        removed_buffer_ids: Vec<BufferId>,
  99    },
 100    ExcerptsExpanded {
 101        ids: Vec<ExcerptId>,
 102    },
 103    ExcerptsEdited {
 104        excerpt_ids: Vec<ExcerptId>,
 105        buffer_ids: Vec<BufferId>,
 106    },
 107    DiffHunksToggled,
 108    Edited {
 109        singleton_buffer_edited: bool,
 110        edited_buffer: Option<Entity<Buffer>>,
 111    },
 112    TransactionUndone {
 113        transaction_id: TransactionId,
 114    },
 115    Reloaded,
 116    ReloadNeeded,
 117
 118    LanguageChanged(BufferId),
 119    CapabilityChanged,
 120    Reparsed(BufferId),
 121    Saved,
 122    FileHandleChanged,
 123    Closed,
 124    Discarded,
 125    DirtyChanged,
 126    DiagnosticsUpdated,
 127    BufferDiffChanged,
 128}
 129
 130/// A diff hunk, representing a range of consequent lines in a multibuffer.
 131#[derive(Debug, Clone, PartialEq, Eq)]
 132pub struct MultiBufferDiffHunk {
 133    /// The row range in the multibuffer where this diff hunk appears.
 134    pub row_range: Range<MultiBufferRow>,
 135    /// The buffer ID that this hunk belongs to.
 136    pub buffer_id: BufferId,
 137    /// The range of the underlying buffer that this hunk corresponds to.
 138    pub buffer_range: Range<text::Anchor>,
 139    /// The excerpt that contains the diff hunk.
 140    pub excerpt_id: ExcerptId,
 141    /// The range within the buffer's diff base that this hunk corresponds to.
 142    pub diff_base_byte_range: Range<usize>,
 143    /// Whether or not this hunk also appears in the 'secondary diff'.
 144    pub secondary_status: DiffHunkSecondaryStatus,
 145}
 146
 147impl MultiBufferDiffHunk {
 148    pub fn status(&self) -> DiffHunkStatus {
 149        let kind = if self.buffer_range.start == self.buffer_range.end {
 150            DiffHunkStatusKind::Deleted
 151        } else if self.diff_base_byte_range.is_empty() {
 152            DiffHunkStatusKind::Added
 153        } else {
 154            DiffHunkStatusKind::Modified
 155        };
 156        DiffHunkStatus {
 157            kind,
 158            secondary: self.secondary_status,
 159        }
 160    }
 161
 162    pub fn is_created_file(&self) -> bool {
 163        self.diff_base_byte_range == (0..0)
 164            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 165    }
 166
 167    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 168        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 169        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 170        start..end
 171    }
 172}
 173
 174#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 175pub struct PathKey {
 176    namespace: u32,
 177    path: Arc<Path>,
 178}
 179
 180impl PathKey {
 181    pub fn namespaced(namespace: u32, path: Arc<Path>) -> Self {
 182        Self { namespace, path }
 183    }
 184
 185    pub fn for_buffer(buffer: &Entity<Buffer>, cx: &App) -> Self {
 186        if let Some(file) = buffer.read(cx).file() {
 187            Self::namespaced(1, Arc::from(file.full_path(cx)))
 188        } else {
 189            Self::namespaced(0, Arc::from(PathBuf::from(buffer.entity_id().to_string())))
 190        }
 191    }
 192
 193    pub fn path(&self) -> &Arc<Path> {
 194        &self.path
 195    }
 196}
 197
 198pub type MultiBufferPoint = Point;
 199type ExcerptOffset = TypedOffset<Excerpt>;
 200type ExcerptPoint = TypedPoint<Excerpt>;
 201
 202#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 203#[serde(transparent)]
 204pub struct MultiBufferRow(pub u32);
 205
 206impl MultiBufferRow {
 207    pub const MIN: Self = Self(0);
 208    pub const MAX: Self = Self(u32::MAX);
 209}
 210
 211impl std::ops::Add<usize> for MultiBufferRow {
 212    type Output = Self;
 213
 214    fn add(self, rhs: usize) -> Self::Output {
 215        MultiBufferRow(self.0 + rhs as u32)
 216    }
 217}
 218
 219#[derive(Clone)]
 220struct History {
 221    next_transaction_id: TransactionId,
 222    undo_stack: Vec<Transaction>,
 223    redo_stack: Vec<Transaction>,
 224    transaction_depth: usize,
 225    group_interval: Duration,
 226}
 227
 228#[derive(Clone)]
 229struct Transaction {
 230    id: TransactionId,
 231    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 232    first_edit_at: Instant,
 233    last_edit_at: Instant,
 234    suppress_grouping: bool,
 235}
 236
 237pub trait ToOffset: 'static + fmt::Debug {
 238    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 239}
 240
 241pub trait ToOffsetUtf16: 'static + fmt::Debug {
 242    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 243}
 244
 245pub trait ToPoint: 'static + fmt::Debug {
 246    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 247}
 248
 249pub trait ToPointUtf16: 'static + fmt::Debug {
 250    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 251}
 252
 253struct BufferState {
 254    buffer: Entity<Buffer>,
 255    last_version: clock::Global,
 256    last_non_text_state_update_count: usize,
 257    excerpts: Vec<Locator>,
 258    _subscriptions: [gpui::Subscription; 2],
 259}
 260
 261struct DiffState {
 262    diff: Entity<BufferDiff>,
 263    _subscription: gpui::Subscription,
 264}
 265
 266impl DiffState {
 267    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 268        DiffState {
 269            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 270                BufferDiffEvent::DiffChanged { changed_range } => {
 271                    if let Some(changed_range) = changed_range.clone() {
 272                        this.buffer_diff_changed(diff, changed_range, cx)
 273                    }
 274                    cx.emit(Event::BufferDiffChanged);
 275                }
 276                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 277                _ => {}
 278            }),
 279            diff,
 280        }
 281    }
 282}
 283
 284/// The contents of a [`MultiBuffer`] at a single point in time.
 285#[derive(Clone, Default)]
 286pub struct MultiBufferSnapshot {
 287    singleton: bool,
 288    excerpts: SumTree<Excerpt>,
 289    excerpt_ids: SumTree<ExcerptIdMapping>,
 290    diffs: TreeMap<BufferId, BufferDiffSnapshot>,
 291    diff_transforms: SumTree<DiffTransform>,
 292    replaced_excerpts: TreeMap<ExcerptId, ExcerptId>,
 293    trailing_excerpt_update_count: usize,
 294    all_diff_hunks_expanded: bool,
 295    non_text_state_update_count: usize,
 296    edit_count: usize,
 297    is_dirty: bool,
 298    has_deleted_file: bool,
 299    has_conflict: bool,
 300    show_headers: bool,
 301}
 302
 303#[derive(Debug, Clone)]
 304enum DiffTransform {
 305    BufferContent {
 306        summary: TextSummary,
 307        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 308    },
 309    DeletedHunk {
 310        summary: TextSummary,
 311        buffer_id: BufferId,
 312        hunk_info: DiffTransformHunkInfo,
 313        base_text_byte_range: Range<usize>,
 314        has_trailing_newline: bool,
 315    },
 316}
 317
 318#[derive(Clone, Copy, Debug)]
 319struct DiffTransformHunkInfo {
 320    excerpt_id: ExcerptId,
 321    hunk_start_anchor: text::Anchor,
 322    hunk_secondary_status: DiffHunkSecondaryStatus,
 323}
 324
 325impl Eq for DiffTransformHunkInfo {}
 326
 327impl PartialEq for DiffTransformHunkInfo {
 328    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 329        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 330    }
 331}
 332
 333impl std::hash::Hash for DiffTransformHunkInfo {
 334    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 335        self.excerpt_id.hash(state);
 336        self.hunk_start_anchor.hash(state);
 337    }
 338}
 339
 340#[derive(Clone)]
 341pub struct ExcerptInfo {
 342    pub id: ExcerptId,
 343    pub buffer: BufferSnapshot,
 344    pub buffer_id: BufferId,
 345    pub range: ExcerptRange<text::Anchor>,
 346    pub end_row: MultiBufferRow,
 347}
 348
 349impl std::fmt::Debug for ExcerptInfo {
 350    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 351        f.debug_struct(type_name::<Self>())
 352            .field("id", &self.id)
 353            .field("buffer_id", &self.buffer_id)
 354            .field("path", &self.buffer.file().map(|f| f.path()))
 355            .field("range", &self.range)
 356            .finish()
 357    }
 358}
 359
 360/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 361#[derive(Debug)]
 362pub struct ExcerptBoundary {
 363    pub prev: Option<ExcerptInfo>,
 364    pub next: ExcerptInfo,
 365    /// The row in the `MultiBuffer` where the boundary is located
 366    pub row: MultiBufferRow,
 367}
 368
 369impl ExcerptBoundary {
 370    pub fn starts_new_buffer(&self) -> bool {
 371        match (self.prev.as_ref(), &self.next) {
 372            (None, _) => true,
 373            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 374        }
 375    }
 376}
 377
 378#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 379pub struct ExpandInfo {
 380    pub direction: ExpandExcerptDirection,
 381    pub excerpt_id: ExcerptId,
 382}
 383
 384#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 385pub struct RowInfo {
 386    pub buffer_id: Option<BufferId>,
 387    pub buffer_row: Option<u32>,
 388    pub multibuffer_row: Option<MultiBufferRow>,
 389    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 390    pub expand_info: Option<ExpandInfo>,
 391}
 392
 393/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 394#[derive(Clone)]
 395struct Excerpt {
 396    /// The unique identifier for this excerpt
 397    id: ExcerptId,
 398    /// The location of the excerpt in the [`MultiBuffer`]
 399    locator: Locator,
 400    /// The buffer being excerpted
 401    buffer_id: BufferId,
 402    /// A snapshot of the buffer being excerpted
 403    buffer: BufferSnapshot,
 404    /// The range of the buffer to be shown in the excerpt
 405    range: ExcerptRange<text::Anchor>,
 406    /// The last row in the excerpted slice of the buffer
 407    max_buffer_row: BufferRow,
 408    /// A summary of the text in the excerpt
 409    text_summary: TextSummary,
 410    has_trailing_newline: bool,
 411}
 412
 413/// A public view into an `Excerpt` in a [`MultiBuffer`].
 414///
 415/// Contains methods for getting the [`Buffer`] of the excerpt,
 416/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 417#[derive(Clone)]
 418pub struct MultiBufferExcerpt<'a> {
 419    excerpt: &'a Excerpt,
 420    diff_transforms: sum_tree::Cursor<'a, DiffTransform, DiffTransforms<usize>>,
 421    offset: usize,
 422    excerpt_offset: ExcerptDimension<usize>,
 423    buffer_offset: usize,
 424}
 425
 426#[derive(Clone, Debug)]
 427struct ExcerptIdMapping {
 428    id: ExcerptId,
 429    locator: Locator,
 430}
 431
 432/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 433/// These ranges are relative to the buffer itself
 434#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 435pub struct ExcerptRange<T> {
 436    /// The full range of text to be shown in the excerpt.
 437    pub context: Range<T>,
 438    /// The primary range of text to be highlighted in the excerpt.
 439    /// In a multi-buffer search, this would be the text that matched the search
 440    pub primary: Range<T>,
 441}
 442
 443impl<T: Clone> ExcerptRange<T> {
 444    pub fn new(context: Range<T>) -> Self {
 445        Self {
 446            context: context.clone(),
 447            primary: context,
 448        }
 449    }
 450}
 451
 452#[derive(Clone, Debug, Default)]
 453pub struct ExcerptSummary {
 454    excerpt_id: ExcerptId,
 455    /// The location of the last [`Excerpt`] being summarized
 456    excerpt_locator: Locator,
 457    widest_line_number: u32,
 458    text: TextSummary,
 459}
 460
 461#[derive(Debug, Clone)]
 462pub struct DiffTransformSummary {
 463    input: TextSummary,
 464    output: TextSummary,
 465}
 466
 467#[derive(Clone)]
 468pub struct MultiBufferRows<'a> {
 469    point: Point,
 470    is_empty: bool,
 471    is_singleton: bool,
 472    cursor: MultiBufferCursor<'a, Point>,
 473}
 474
 475pub struct MultiBufferChunks<'a> {
 476    excerpts: Cursor<'a, Excerpt, ExcerptOffset>,
 477    diff_transforms: Cursor<'a, DiffTransform, Dimensions<usize, ExcerptOffset>>,
 478    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 479    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 480    buffer_chunk: Option<Chunk<'a>>,
 481    range: Range<usize>,
 482    excerpt_offset_range: Range<ExcerptOffset>,
 483    excerpt_chunks: Option<ExcerptChunks<'a>>,
 484    language_aware: bool,
 485}
 486
 487pub struct ReversedMultiBufferChunks<'a> {
 488    cursor: MultiBufferCursor<'a, usize>,
 489    current_chunks: Option<rope::Chunks<'a>>,
 490    start: usize,
 491    offset: usize,
 492}
 493
 494pub struct MultiBufferBytes<'a> {
 495    range: Range<usize>,
 496    cursor: MultiBufferCursor<'a, usize>,
 497    excerpt_bytes: Option<text::Bytes<'a>>,
 498    has_trailing_newline: bool,
 499    chunk: &'a [u8],
 500}
 501
 502pub struct ReversedMultiBufferBytes<'a> {
 503    range: Range<usize>,
 504    chunks: ReversedMultiBufferChunks<'a>,
 505    chunk: &'a [u8],
 506}
 507
 508#[derive(Clone)]
 509struct DiffTransforms<D> {
 510    output_dimension: OutputDimension<D>,
 511    excerpt_dimension: ExcerptDimension<D>,
 512}
 513
 514impl<'a, D: TextDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<D> {
 515    fn zero(cx: &<DiffTransformSummary as sum_tree::Summary>::Context) -> Self {
 516        Self {
 517            output_dimension: OutputDimension::zero(cx),
 518            excerpt_dimension: <ExcerptDimension<D> as Dimension<'a, DiffTransformSummary>>::zero(
 519                cx,
 520            ),
 521        }
 522    }
 523
 524    fn add_summary(
 525        &mut self,
 526        summary: &'a DiffTransformSummary,
 527        cx: &<DiffTransformSummary as sum_tree::Summary>::Context,
 528    ) {
 529        self.output_dimension.add_summary(summary, cx);
 530        self.excerpt_dimension.add_summary(summary, cx);
 531    }
 532}
 533
 534#[derive(Clone)]
 535struct MultiBufferCursor<'a, D: TextDimension> {
 536    excerpts: Cursor<'a, Excerpt, ExcerptDimension<D>>,
 537    diff_transforms: Cursor<'a, DiffTransform, DiffTransforms<D>>,
 538    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 539    cached_region: Option<MultiBufferRegion<'a, D>>,
 540}
 541
 542#[derive(Clone)]
 543struct MultiBufferRegion<'a, D: TextDimension> {
 544    buffer: &'a BufferSnapshot,
 545    is_main_buffer: bool,
 546    diff_hunk_status: Option<DiffHunkStatus>,
 547    excerpt: &'a Excerpt,
 548    buffer_range: Range<D>,
 549    range: Range<D>,
 550    has_trailing_newline: bool,
 551}
 552
 553struct ExcerptChunks<'a> {
 554    excerpt_id: ExcerptId,
 555    content_chunks: BufferChunks<'a>,
 556    footer_height: usize,
 557}
 558
 559#[derive(Debug)]
 560struct BufferEdit {
 561    range: Range<usize>,
 562    new_text: Arc<str>,
 563    is_insertion: bool,
 564    original_indent_column: Option<u32>,
 565    excerpt_id: ExcerptId,
 566}
 567
 568#[derive(Clone, Copy, Debug, PartialEq)]
 569enum DiffChangeKind {
 570    BufferEdited,
 571    DiffUpdated { base_changed: bool },
 572    ExpandOrCollapseHunks { expand: bool },
 573}
 574
 575#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 576pub enum ExpandExcerptDirection {
 577    Up,
 578    Down,
 579    UpAndDown,
 580}
 581
 582impl ExpandExcerptDirection {
 583    pub fn should_expand_up(&self) -> bool {
 584        match self {
 585            ExpandExcerptDirection::Up => true,
 586            ExpandExcerptDirection::Down => false,
 587            ExpandExcerptDirection::UpAndDown => true,
 588        }
 589    }
 590
 591    pub fn should_expand_down(&self) -> bool {
 592        match self {
 593            ExpandExcerptDirection::Up => false,
 594            ExpandExcerptDirection::Down => true,
 595            ExpandExcerptDirection::UpAndDown => true,
 596        }
 597    }
 598}
 599
 600#[derive(Clone, Debug, PartialEq)]
 601pub struct IndentGuide {
 602    pub buffer_id: BufferId,
 603    pub start_row: MultiBufferRow,
 604    pub end_row: MultiBufferRow,
 605    pub depth: u32,
 606    pub tab_size: u32,
 607    pub settings: IndentGuideSettings,
 608}
 609
 610impl IndentGuide {
 611    pub fn indent_level(&self) -> u32 {
 612        self.depth * self.tab_size
 613    }
 614}
 615
 616impl MultiBuffer {
 617    pub fn new(capability: Capability) -> Self {
 618        Self {
 619            snapshot: RefCell::new(MultiBufferSnapshot {
 620                show_headers: true,
 621                ..MultiBufferSnapshot::default()
 622            }),
 623            buffers: RefCell::default(),
 624            diffs: HashMap::default(),
 625            subscriptions: Topic::default(),
 626            singleton: false,
 627            capability,
 628            title: None,
 629            excerpts_by_path: Default::default(),
 630            paths_by_excerpt: Default::default(),
 631            buffer_changed_since_sync: Default::default(),
 632            history: History {
 633                next_transaction_id: clock::Lamport::default(),
 634                undo_stack: Vec::new(),
 635                redo_stack: Vec::new(),
 636                transaction_depth: 0,
 637                group_interval: Duration::from_millis(300),
 638            },
 639        }
 640    }
 641
 642    pub fn without_headers(capability: Capability) -> Self {
 643        Self {
 644            snapshot: Default::default(),
 645            buffers: Default::default(),
 646            excerpts_by_path: Default::default(),
 647            paths_by_excerpt: Default::default(),
 648            diffs: HashMap::default(),
 649            subscriptions: Default::default(),
 650            singleton: false,
 651            capability,
 652            buffer_changed_since_sync: Default::default(),
 653            history: History {
 654                next_transaction_id: Default::default(),
 655                undo_stack: Default::default(),
 656                redo_stack: Default::default(),
 657                transaction_depth: 0,
 658                group_interval: Duration::from_millis(300),
 659            },
 660            title: Default::default(),
 661        }
 662    }
 663
 664    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
 665        let mut buffers = HashMap::default();
 666        let buffer_changed_since_sync = Rc::new(Cell::new(false));
 667        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 668            buffer_state.buffer.update(new_cx, |buffer, _| {
 669                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
 670            });
 671            buffers.insert(
 672                *buffer_id,
 673                BufferState {
 674                    buffer: buffer_state.buffer.clone(),
 675                    last_version: buffer_state.last_version.clone(),
 676                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 677                    excerpts: buffer_state.excerpts.clone(),
 678                    _subscriptions: [
 679                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 680                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 681                    ],
 682                },
 683            );
 684        }
 685        let mut diff_bases = HashMap::default();
 686        for (buffer_id, diff) in self.diffs.iter() {
 687            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
 688        }
 689        Self {
 690            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 691            buffers: RefCell::new(buffers),
 692            excerpts_by_path: Default::default(),
 693            paths_by_excerpt: Default::default(),
 694            diffs: diff_bases,
 695            subscriptions: Default::default(),
 696            singleton: self.singleton,
 697            capability: self.capability,
 698            history: self.history.clone(),
 699            title: self.title.clone(),
 700            buffer_changed_since_sync,
 701        }
 702    }
 703
 704    pub fn with_title(mut self, title: String) -> Self {
 705        self.title = Some(title);
 706        self
 707    }
 708
 709    pub fn read_only(&self) -> bool {
 710        self.capability == Capability::ReadOnly
 711    }
 712
 713    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
 714        let mut this = Self::new(buffer.read(cx).capability());
 715        this.singleton = true;
 716        this.push_excerpts(
 717            buffer,
 718            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
 719            cx,
 720        );
 721        this.snapshot.borrow_mut().singleton = true;
 722        this
 723    }
 724
 725    /// Returns an up-to-date snapshot of the MultiBuffer.
 726    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
 727        self.sync(cx);
 728        self.snapshot.borrow().clone()
 729    }
 730
 731    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
 732        self.sync(cx);
 733        self.snapshot.borrow()
 734    }
 735
 736    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
 737        if self.singleton {
 738            return Some(
 739                self.buffers
 740                    .borrow()
 741                    .values()
 742                    .next()
 743                    .unwrap()
 744                    .buffer
 745                    .clone(),
 746            );
 747        } else {
 748            None
 749        }
 750    }
 751
 752    pub fn is_singleton(&self) -> bool {
 753        self.singleton
 754    }
 755
 756    pub fn subscribe(&mut self) -> Subscription {
 757        self.subscriptions.subscribe()
 758    }
 759
 760    pub fn is_dirty(&self, cx: &App) -> bool {
 761        self.read(cx).is_dirty()
 762    }
 763
 764    pub fn has_deleted_file(&self, cx: &App) -> bool {
 765        self.read(cx).has_deleted_file()
 766    }
 767
 768    pub fn has_conflict(&self, cx: &App) -> bool {
 769        self.read(cx).has_conflict()
 770    }
 771
 772    // The `is_empty` signature doesn't match what clippy expects
 773    #[allow(clippy::len_without_is_empty)]
 774    pub fn len(&self, cx: &App) -> usize {
 775        self.read(cx).len()
 776    }
 777
 778    pub fn is_empty(&self) -> bool {
 779        self.buffers.borrow().is_empty()
 780    }
 781
 782    pub fn symbols_containing<T: ToOffset>(
 783        &self,
 784        offset: T,
 785        theme: Option<&SyntaxTheme>,
 786        cx: &App,
 787    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 788        self.read(cx).symbols_containing(offset, theme)
 789    }
 790
 791    pub fn edit<I, S, T>(
 792        &self,
 793        edits: I,
 794        autoindent_mode: Option<AutoindentMode>,
 795        cx: &mut Context<Self>,
 796    ) where
 797        I: IntoIterator<Item = (Range<S>, T)>,
 798        S: ToOffset,
 799        T: Into<Arc<str>>,
 800    {
 801        let snapshot = self.read(cx);
 802        let edits = edits
 803            .into_iter()
 804            .map(|(range, new_text)| {
 805                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 806                if range.start > range.end {
 807                    mem::swap(&mut range.start, &mut range.end);
 808                }
 809                (range, new_text.into())
 810            })
 811            .collect::<Vec<_>>();
 812
 813        return edit_internal(self, snapshot, edits, autoindent_mode, cx);
 814
 815        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 816        fn edit_internal(
 817            this: &MultiBuffer,
 818            snapshot: Ref<MultiBufferSnapshot>,
 819            edits: Vec<(Range<usize>, Arc<str>)>,
 820            mut autoindent_mode: Option<AutoindentMode>,
 821            cx: &mut Context<MultiBuffer>,
 822        ) {
 823            if this.read_only() || this.buffers.borrow().is_empty() {
 824                return;
 825            }
 826
 827            let original_indent_columns = match &mut autoindent_mode {
 828                Some(AutoindentMode::Block {
 829                    original_indent_columns,
 830                }) => mem::take(original_indent_columns),
 831                _ => Default::default(),
 832            };
 833
 834            let (buffer_edits, edited_excerpt_ids) =
 835                this.convert_edits_to_buffer_edits(edits, &snapshot, &original_indent_columns);
 836            drop(snapshot);
 837
 838            let mut buffer_ids = Vec::new();
 839            for (buffer_id, mut edits) in buffer_edits {
 840                buffer_ids.push(buffer_id);
 841                edits.sort_by_key(|edit| edit.range.start);
 842                this.buffers.borrow()[&buffer_id]
 843                    .buffer
 844                    .update(cx, |buffer, cx| {
 845                        let mut edits = edits.into_iter().peekable();
 846                        let mut insertions = Vec::new();
 847                        let mut original_indent_columns = Vec::new();
 848                        let mut deletions = Vec::new();
 849                        let empty_str: Arc<str> = Arc::default();
 850                        while let Some(BufferEdit {
 851                            mut range,
 852                            mut new_text,
 853                            mut is_insertion,
 854                            original_indent_column,
 855                            excerpt_id,
 856                        }) = edits.next()
 857                        {
 858                            while let Some(BufferEdit {
 859                                range: next_range,
 860                                is_insertion: next_is_insertion,
 861                                new_text: next_new_text,
 862                                excerpt_id: next_excerpt_id,
 863                                ..
 864                            }) = edits.peek()
 865                            {
 866                                if range.end >= next_range.start {
 867                                    range.end = cmp::max(next_range.end, range.end);
 868                                    is_insertion |= *next_is_insertion;
 869                                    if excerpt_id == *next_excerpt_id {
 870                                        new_text = format!("{new_text}{next_new_text}").into();
 871                                    }
 872                                    edits.next();
 873                                } else {
 874                                    break;
 875                                }
 876                            }
 877
 878                            if is_insertion {
 879                                original_indent_columns.push(original_indent_column);
 880                                insertions.push((
 881                                    buffer.anchor_before(range.start)
 882                                        ..buffer.anchor_before(range.end),
 883                                    new_text.clone(),
 884                                ));
 885                            } else if !range.is_empty() {
 886                                deletions.push((
 887                                    buffer.anchor_before(range.start)
 888                                        ..buffer.anchor_before(range.end),
 889                                    empty_str.clone(),
 890                                ));
 891                            }
 892                        }
 893
 894                        let deletion_autoindent_mode =
 895                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 896                                Some(AutoindentMode::Block {
 897                                    original_indent_columns: Default::default(),
 898                                })
 899                            } else {
 900                                autoindent_mode.clone()
 901                            };
 902                        let insertion_autoindent_mode =
 903                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 904                                Some(AutoindentMode::Block {
 905                                    original_indent_columns,
 906                                })
 907                            } else {
 908                                autoindent_mode.clone()
 909                            };
 910
 911                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 912                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 913                    })
 914            }
 915
 916            cx.emit(Event::ExcerptsEdited {
 917                excerpt_ids: edited_excerpt_ids,
 918                buffer_ids,
 919            });
 920        }
 921    }
 922
 923    fn convert_edits_to_buffer_edits(
 924        &self,
 925        edits: Vec<(Range<usize>, Arc<str>)>,
 926        snapshot: &MultiBufferSnapshot,
 927        original_indent_columns: &[Option<u32>],
 928    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
 929        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 930        let mut edited_excerpt_ids = Vec::new();
 931        let mut cursor = snapshot.cursor::<usize>();
 932        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
 933            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
 934
 935            cursor.seek(&range.start);
 936            let mut start_region = cursor.region().expect("start offset out of bounds");
 937            if !start_region.is_main_buffer {
 938                cursor.next();
 939                if let Some(region) = cursor.region() {
 940                    start_region = region;
 941                } else {
 942                    continue;
 943                }
 944            }
 945
 946            if range.end < start_region.range.start {
 947                continue;
 948            }
 949
 950            if range.end > start_region.range.end {
 951                cursor.seek_forward(&range.end);
 952            }
 953            let mut end_region = cursor.region().expect("end offset out of bounds");
 954            if !end_region.is_main_buffer {
 955                cursor.prev();
 956                if let Some(region) = cursor.region() {
 957                    end_region = region;
 958                } else {
 959                    continue;
 960                }
 961            }
 962
 963            if range.start > end_region.range.end {
 964                continue;
 965            }
 966
 967            let start_overshoot = range.start.saturating_sub(start_region.range.start);
 968            let end_overshoot = range.end.saturating_sub(end_region.range.start);
 969            let buffer_start = (start_region.buffer_range.start + start_overshoot)
 970                .min(start_region.buffer_range.end);
 971            let buffer_end =
 972                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
 973
 974            if start_region.excerpt.id == end_region.excerpt.id {
 975                if start_region.is_main_buffer {
 976                    edited_excerpt_ids.push(start_region.excerpt.id);
 977                    buffer_edits
 978                        .entry(start_region.buffer.remote_id())
 979                        .or_default()
 980                        .push(BufferEdit {
 981                            range: buffer_start..buffer_end,
 982                            new_text,
 983                            is_insertion: true,
 984                            original_indent_column,
 985                            excerpt_id: start_region.excerpt.id,
 986                        });
 987                }
 988            } else {
 989                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
 990                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
 991                if start_region.is_main_buffer {
 992                    edited_excerpt_ids.push(start_region.excerpt.id);
 993                    buffer_edits
 994                        .entry(start_region.buffer.remote_id())
 995                        .or_default()
 996                        .push(BufferEdit {
 997                            range: start_excerpt_range,
 998                            new_text: new_text.clone(),
 999                            is_insertion: true,
1000                            original_indent_column,
1001                            excerpt_id: start_region.excerpt.id,
1002                        });
1003                }
1004                if end_region.is_main_buffer {
1005                    edited_excerpt_ids.push(end_region.excerpt.id);
1006                    buffer_edits
1007                        .entry(end_region.buffer.remote_id())
1008                        .or_default()
1009                        .push(BufferEdit {
1010                            range: end_excerpt_range,
1011                            new_text: new_text.clone(),
1012                            is_insertion: false,
1013                            original_indent_column,
1014                            excerpt_id: end_region.excerpt.id,
1015                        });
1016                }
1017
1018                cursor.seek(&range.start);
1019                cursor.next_excerpt();
1020                while let Some(region) = cursor.region() {
1021                    if region.excerpt.id == end_region.excerpt.id {
1022                        break;
1023                    }
1024                    if region.is_main_buffer {
1025                        edited_excerpt_ids.push(region.excerpt.id);
1026                        buffer_edits
1027                            .entry(region.buffer.remote_id())
1028                            .or_default()
1029                            .push(BufferEdit {
1030                                range: region.buffer_range,
1031                                new_text: new_text.clone(),
1032                                is_insertion: false,
1033                                original_indent_column,
1034                                excerpt_id: region.excerpt.id,
1035                            });
1036                    }
1037                    cursor.next_excerpt();
1038                }
1039            }
1040        }
1041        (buffer_edits, edited_excerpt_ids)
1042    }
1043
1044    pub fn autoindent_ranges<I, S>(&self, ranges: I, cx: &mut Context<Self>)
1045    where
1046        I: IntoIterator<Item = Range<S>>,
1047        S: ToOffset,
1048    {
1049        let snapshot = self.read(cx);
1050        let empty = Arc::<str>::from("");
1051        let edits = ranges
1052            .into_iter()
1053            .map(|range| {
1054                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
1055                if range.start > range.end {
1056                    mem::swap(&mut range.start, &mut range.end);
1057                }
1058                (range, empty.clone())
1059            })
1060            .collect::<Vec<_>>();
1061
1062        return autoindent_ranges_internal(self, snapshot, edits, cx);
1063
1064        fn autoindent_ranges_internal(
1065            this: &MultiBuffer,
1066            snapshot: Ref<MultiBufferSnapshot>,
1067            edits: Vec<(Range<usize>, Arc<str>)>,
1068            cx: &mut Context<MultiBuffer>,
1069        ) {
1070            if this.read_only() || this.buffers.borrow().is_empty() {
1071                return;
1072            }
1073
1074            let (buffer_edits, edited_excerpt_ids) =
1075                this.convert_edits_to_buffer_edits(edits, &snapshot, &[]);
1076            drop(snapshot);
1077
1078            let mut buffer_ids = Vec::new();
1079            for (buffer_id, mut edits) in buffer_edits {
1080                buffer_ids.push(buffer_id);
1081                edits.sort_unstable_by_key(|edit| edit.range.start);
1082
1083                let mut ranges: Vec<Range<usize>> = Vec::new();
1084                for edit in edits {
1085                    if let Some(last_range) = ranges.last_mut()
1086                        && edit.range.start <= last_range.end
1087                    {
1088                        last_range.end = last_range.end.max(edit.range.end);
1089                        continue;
1090                    }
1091                    ranges.push(edit.range);
1092                }
1093
1094                this.buffers.borrow()[&buffer_id]
1095                    .buffer
1096                    .update(cx, |buffer, cx| {
1097                        buffer.autoindent_ranges(ranges, cx);
1098                    })
1099            }
1100
1101            cx.emit(Event::ExcerptsEdited {
1102                excerpt_ids: edited_excerpt_ids,
1103                buffer_ids,
1104            });
1105        }
1106    }
1107
1108    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
1109    // You can also request the insertion of empty lines above and below the line starting at the returned point.
1110    // Panics if the given position is invalid.
1111    pub fn insert_empty_line(
1112        &mut self,
1113        position: impl ToPoint,
1114        space_above: bool,
1115        space_below: bool,
1116        cx: &mut Context<Self>,
1117    ) -> Point {
1118        let multibuffer_point = position.to_point(&self.read(cx));
1119        let (buffer, buffer_point, _) = self.point_to_buffer_point(multibuffer_point, cx).unwrap();
1120        self.start_transaction(cx);
1121        let empty_line_start = buffer.update(cx, |buffer, cx| {
1122            buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
1123        });
1124        self.end_transaction(cx);
1125        multibuffer_point + (empty_line_start - buffer_point)
1126    }
1127
1128    pub fn start_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1129        self.start_transaction_at(Instant::now(), cx)
1130    }
1131
1132    pub fn start_transaction_at(
1133        &mut self,
1134        now: Instant,
1135        cx: &mut Context<Self>,
1136    ) -> Option<TransactionId> {
1137        if let Some(buffer) = self.as_singleton() {
1138            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1139        }
1140
1141        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1142            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1143        }
1144        self.history.start_transaction(now)
1145    }
1146
1147    pub fn last_transaction_id(&self, cx: &App) -> Option<TransactionId> {
1148        if let Some(buffer) = self.as_singleton() {
1149            buffer
1150                .read(cx)
1151                .peek_undo_stack()
1152                .map(|history_entry| history_entry.transaction_id())
1153        } else {
1154            let last_transaction = self.history.undo_stack.last()?;
1155            Some(last_transaction.id)
1156        }
1157    }
1158
1159    pub fn end_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1160        self.end_transaction_at(Instant::now(), cx)
1161    }
1162
1163    pub fn end_transaction_at(
1164        &mut self,
1165        now: Instant,
1166        cx: &mut Context<Self>,
1167    ) -> Option<TransactionId> {
1168        if let Some(buffer) = self.as_singleton() {
1169            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
1170        }
1171
1172        let mut buffer_transactions = HashMap::default();
1173        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1174            if let Some(transaction_id) =
1175                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
1176            {
1177                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
1178            }
1179        }
1180
1181        if self.history.end_transaction(now, buffer_transactions) {
1182            let transaction_id = self.history.group().unwrap();
1183            Some(transaction_id)
1184        } else {
1185            None
1186        }
1187    }
1188
1189    pub fn edited_ranges_for_transaction<D>(
1190        &self,
1191        transaction_id: TransactionId,
1192        cx: &App,
1193    ) -> Vec<Range<D>>
1194    where
1195        D: TextDimension + Ord + Sub<D, Output = D>,
1196    {
1197        let Some(transaction) = self.history.transaction(transaction_id) else {
1198            return Vec::new();
1199        };
1200
1201        let mut ranges = Vec::new();
1202        let snapshot = self.read(cx);
1203        let buffers = self.buffers.borrow();
1204        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(&());
1205
1206        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
1207            let Some(buffer_state) = buffers.get(buffer_id) else {
1208                continue;
1209            };
1210
1211            let buffer = buffer_state.buffer.read(cx);
1212            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
1213                for excerpt_id in &buffer_state.excerpts {
1214                    cursor.seek(excerpt_id, Bias::Left);
1215                    if let Some(excerpt) = cursor.item()
1216                        && excerpt.locator == *excerpt_id
1217                    {
1218                        let excerpt_buffer_start = excerpt.range.context.start.summary::<D>(buffer);
1219                        let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
1220                        let excerpt_range = excerpt_buffer_start..excerpt_buffer_end;
1221                        if excerpt_range.contains(&range.start)
1222                            && excerpt_range.contains(&range.end)
1223                        {
1224                            let excerpt_start = D::from_text_summary(&cursor.start().text);
1225
1226                            let mut start = excerpt_start;
1227                            start.add_assign(&(range.start - excerpt_buffer_start));
1228                            let mut end = excerpt_start;
1229                            end.add_assign(&(range.end - excerpt_buffer_start));
1230
1231                            ranges.push(start..end);
1232                            break;
1233                        }
1234                    }
1235                }
1236            }
1237        }
1238
1239        ranges.sort_by_key(|range| range.start);
1240        ranges
1241    }
1242
1243    pub fn merge_transactions(
1244        &mut self,
1245        transaction: TransactionId,
1246        destination: TransactionId,
1247        cx: &mut Context<Self>,
1248    ) {
1249        if let Some(buffer) = self.as_singleton() {
1250            buffer.update(cx, |buffer, _| {
1251                buffer.merge_transactions(transaction, destination)
1252            });
1253        } else if let Some(transaction) = self.history.forget(transaction)
1254            && let Some(destination) = self.history.transaction_mut(destination)
1255        {
1256            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1257                if let Some(destination_buffer_transaction_id) =
1258                    destination.buffer_transactions.get(&buffer_id)
1259                {
1260                    if let Some(state) = self.buffers.borrow().get(&buffer_id) {
1261                        state.buffer.update(cx, |buffer, _| {
1262                            buffer.merge_transactions(
1263                                buffer_transaction_id,
1264                                *destination_buffer_transaction_id,
1265                            )
1266                        });
1267                    }
1268                } else {
1269                    destination
1270                        .buffer_transactions
1271                        .insert(buffer_id, buffer_transaction_id);
1272                }
1273            }
1274        }
1275    }
1276
1277    pub fn finalize_last_transaction(&mut self, cx: &mut Context<Self>) {
1278        self.history.finalize_last_transaction();
1279        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1280            buffer.update(cx, |buffer, _| {
1281                buffer.finalize_last_transaction();
1282            });
1283        }
1284    }
1285
1286    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &Context<Self>)
1287    where
1288        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
1289    {
1290        self.history
1291            .push_transaction(buffer_transactions, Instant::now(), cx);
1292        self.history.finalize_last_transaction();
1293    }
1294
1295    pub fn group_until_transaction(
1296        &mut self,
1297        transaction_id: TransactionId,
1298        cx: &mut Context<Self>,
1299    ) {
1300        if let Some(buffer) = self.as_singleton() {
1301            buffer.update(cx, |buffer, _| {
1302                buffer.group_until_transaction(transaction_id)
1303            });
1304        } else {
1305            self.history.group_until(transaction_id);
1306        }
1307    }
1308
1309    pub fn set_active_selections(
1310        &self,
1311        selections: &[Selection<Anchor>],
1312        line_mode: bool,
1313        cursor_shape: CursorShape,
1314        cx: &mut Context<Self>,
1315    ) {
1316        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1317            Default::default();
1318        let snapshot = self.read(cx);
1319        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1320        for selection in selections {
1321            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1322            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1323
1324            cursor.seek(&Some(start_locator), Bias::Left);
1325            while let Some(excerpt) = cursor.item() {
1326                if excerpt.locator > *end_locator {
1327                    break;
1328                }
1329
1330                let mut start = excerpt.range.context.start;
1331                let mut end = excerpt.range.context.end;
1332                if excerpt.id == selection.start.excerpt_id {
1333                    start = selection.start.text_anchor;
1334                }
1335                if excerpt.id == selection.end.excerpt_id {
1336                    end = selection.end.text_anchor;
1337                }
1338                selections_by_buffer
1339                    .entry(excerpt.buffer_id)
1340                    .or_default()
1341                    .push(Selection {
1342                        id: selection.id,
1343                        start,
1344                        end,
1345                        reversed: selection.reversed,
1346                        goal: selection.goal,
1347                    });
1348
1349                cursor.next();
1350            }
1351        }
1352
1353        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1354            if !selections_by_buffer.contains_key(buffer_id) {
1355                buffer_state
1356                    .buffer
1357                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1358            }
1359        }
1360
1361        for (buffer_id, mut selections) in selections_by_buffer {
1362            self.buffers.borrow()[&buffer_id]
1363                .buffer
1364                .update(cx, |buffer, cx| {
1365                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1366                    let mut selections = selections.into_iter().peekable();
1367                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1368                        let mut selection = selections.next()?;
1369                        while let Some(next_selection) = selections.peek() {
1370                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1371                                let next_selection = selections.next().unwrap();
1372                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1373                                    selection.end = next_selection.end;
1374                                }
1375                            } else {
1376                                break;
1377                            }
1378                        }
1379                        Some(selection)
1380                    }));
1381                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1382                });
1383        }
1384    }
1385
1386    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1387        for buffer in self.buffers.borrow().values() {
1388            buffer
1389                .buffer
1390                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1391        }
1392    }
1393
1394    pub fn undo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1395        let mut transaction_id = None;
1396        if let Some(buffer) = self.as_singleton() {
1397            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1398        } else {
1399            while let Some(transaction) = self.history.pop_undo() {
1400                let mut undone = false;
1401                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1402                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1403                        undone |= buffer.update(cx, |buffer, cx| {
1404                            let undo_to = *buffer_transaction_id;
1405                            if let Some(entry) = buffer.peek_undo_stack() {
1406                                *buffer_transaction_id = entry.transaction_id();
1407                            }
1408                            buffer.undo_to_transaction(undo_to, cx)
1409                        });
1410                    }
1411                }
1412
1413                if undone {
1414                    transaction_id = Some(transaction.id);
1415                    break;
1416                }
1417            }
1418        }
1419
1420        if let Some(transaction_id) = transaction_id {
1421            cx.emit(Event::TransactionUndone { transaction_id });
1422        }
1423
1424        transaction_id
1425    }
1426
1427    pub fn redo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1428        if let Some(buffer) = self.as_singleton() {
1429            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1430        }
1431
1432        while let Some(transaction) = self.history.pop_redo() {
1433            let mut redone = false;
1434            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1435                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1436                    redone |= buffer.update(cx, |buffer, cx| {
1437                        let redo_to = *buffer_transaction_id;
1438                        if let Some(entry) = buffer.peek_redo_stack() {
1439                            *buffer_transaction_id = entry.transaction_id();
1440                        }
1441                        buffer.redo_to_transaction(redo_to, cx)
1442                    });
1443                }
1444            }
1445
1446            if redone {
1447                return Some(transaction.id);
1448            }
1449        }
1450
1451        None
1452    }
1453
1454    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1455        if let Some(buffer) = self.as_singleton() {
1456            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1457        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1458            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1459                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1460                    buffer.update(cx, |buffer, cx| {
1461                        buffer.undo_transaction(*transaction_id, cx)
1462                    });
1463                }
1464            }
1465        }
1466    }
1467
1468    pub fn forget_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1469        if let Some(buffer) = self.as_singleton() {
1470            buffer.update(cx, |buffer, _| {
1471                buffer.forget_transaction(transaction_id);
1472            });
1473        } else if let Some(transaction) = self.history.forget(transaction_id) {
1474            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1475                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1476                    state.buffer.update(cx, |buffer, _| {
1477                        buffer.forget_transaction(buffer_transaction_id);
1478                    });
1479                }
1480            }
1481        }
1482    }
1483
1484    pub fn push_excerpts<O>(
1485        &mut self,
1486        buffer: Entity<Buffer>,
1487        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1488        cx: &mut Context<Self>,
1489    ) -> Vec<ExcerptId>
1490    where
1491        O: text::ToOffset,
1492    {
1493        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1494    }
1495
1496    pub fn location_for_path(&self, path: &PathKey, cx: &App) -> Option<Anchor> {
1497        let excerpt_id = self.excerpts_by_path.get(path)?.first()?;
1498        let snapshot = self.snapshot(cx);
1499        let excerpt = snapshot.excerpt(*excerpt_id)?;
1500        Some(Anchor::in_buffer(
1501            *excerpt_id,
1502            excerpt.buffer_id,
1503            excerpt.range.context.start,
1504        ))
1505    }
1506
1507    pub fn excerpt_paths(&self) -> impl Iterator<Item = &PathKey> {
1508        self.excerpts_by_path.keys()
1509    }
1510
1511    fn expand_excerpts_with_paths(
1512        &mut self,
1513        ids: impl IntoIterator<Item = ExcerptId>,
1514        line_count: u32,
1515        direction: ExpandExcerptDirection,
1516        cx: &mut Context<Self>,
1517    ) {
1518        let grouped = ids
1519            .into_iter()
1520            .chunk_by(|id| self.paths_by_excerpt.get(id).cloned())
1521            .into_iter()
1522            .flat_map(|(k, v)| Some((k?, v.into_iter().collect::<Vec<_>>())))
1523            .collect::<Vec<_>>();
1524        let snapshot = self.snapshot(cx);
1525
1526        for (path, ids) in grouped.into_iter() {
1527            let Some(excerpt_ids) = self.excerpts_by_path.get(&path) else {
1528                continue;
1529            };
1530
1531            let ids_to_expand = HashSet::from_iter(ids);
1532            let expanded_ranges = excerpt_ids.iter().filter_map(|excerpt_id| {
1533                let excerpt = snapshot.excerpt(*excerpt_id)?;
1534
1535                let mut context = excerpt.range.context.to_point(&excerpt.buffer);
1536                if ids_to_expand.contains(excerpt_id) {
1537                    match direction {
1538                        ExpandExcerptDirection::Up => {
1539                            context.start.row = context.start.row.saturating_sub(line_count);
1540                            context.start.column = 0;
1541                        }
1542                        ExpandExcerptDirection::Down => {
1543                            context.end.row =
1544                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1545                            context.end.column = excerpt.buffer.line_len(context.end.row);
1546                        }
1547                        ExpandExcerptDirection::UpAndDown => {
1548                            context.start.row = context.start.row.saturating_sub(line_count);
1549                            context.start.column = 0;
1550                            context.end.row =
1551                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1552                            context.end.column = excerpt.buffer.line_len(context.end.row);
1553                        }
1554                    }
1555                }
1556
1557                Some(ExcerptRange {
1558                    context,
1559                    primary: excerpt.range.primary.to_point(&excerpt.buffer),
1560                })
1561            });
1562            let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1563            for range in expanded_ranges {
1564                if let Some(last_range) = merged_ranges.last_mut()
1565                    && last_range.context.end >= range.context.start
1566                {
1567                    last_range.context.end = range.context.end;
1568                    continue;
1569                }
1570                merged_ranges.push(range)
1571            }
1572            let Some(excerpt_id) = excerpt_ids.first() else {
1573                continue;
1574            };
1575            let Some(buffer_id) = &snapshot.buffer_id_for_excerpt(*excerpt_id) else {
1576                continue;
1577            };
1578
1579            let Some(buffer) = self
1580                .buffers
1581                .borrow()
1582                .get(buffer_id)
1583                .map(|b| b.buffer.clone())
1584            else {
1585                continue;
1586            };
1587
1588            let buffer_snapshot = buffer.read(cx).snapshot();
1589            self.update_path_excerpts(path.clone(), buffer, &buffer_snapshot, merged_ranges, cx);
1590        }
1591    }
1592
1593    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1594    pub fn set_excerpts_for_path(
1595        &mut self,
1596        path: PathKey,
1597        buffer: Entity<Buffer>,
1598        ranges: impl IntoIterator<Item = Range<Point>>,
1599        context_line_count: u32,
1600        cx: &mut Context<Self>,
1601    ) -> (Vec<Range<Anchor>>, bool) {
1602        let buffer_snapshot = buffer.read(cx).snapshot();
1603        let excerpt_ranges = build_excerpt_ranges(ranges, context_line_count, &buffer_snapshot);
1604
1605        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1606        self.set_merged_excerpt_ranges_for_path(
1607            path,
1608            buffer,
1609            excerpt_ranges,
1610            &buffer_snapshot,
1611            new,
1612            counts,
1613            cx,
1614        )
1615    }
1616
1617    pub fn set_excerpt_ranges_for_path(
1618        &mut self,
1619        path: PathKey,
1620        buffer: Entity<Buffer>,
1621        buffer_snapshot: &BufferSnapshot,
1622        excerpt_ranges: Vec<ExcerptRange<Point>>,
1623        cx: &mut Context<Self>,
1624    ) -> (Vec<Range<Anchor>>, bool) {
1625        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1626        self.set_merged_excerpt_ranges_for_path(
1627            path,
1628            buffer,
1629            excerpt_ranges,
1630            buffer_snapshot,
1631            new,
1632            counts,
1633            cx,
1634        )
1635    }
1636
1637    pub fn set_anchored_excerpts_for_path(
1638        &self,
1639        buffer: Entity<Buffer>,
1640        ranges: Vec<Range<text::Anchor>>,
1641        context_line_count: u32,
1642        cx: &mut Context<Self>,
1643    ) -> Task<Vec<Range<Anchor>>> {
1644        let buffer_snapshot = buffer.read(cx).snapshot();
1645        let path_key = PathKey::for_buffer(&buffer, cx);
1646        cx.spawn(async move |multi_buffer, cx| {
1647            let snapshot = buffer_snapshot.clone();
1648            let (excerpt_ranges, new, counts) = cx
1649                .background_spawn(async move {
1650                    let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
1651                    let excerpt_ranges =
1652                        build_excerpt_ranges(ranges, context_line_count, &snapshot);
1653                    let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1654                    (excerpt_ranges, new, counts)
1655                })
1656                .await;
1657
1658            multi_buffer
1659                .update(cx, move |multi_buffer, cx| {
1660                    let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
1661                        path_key,
1662                        buffer,
1663                        excerpt_ranges,
1664                        &buffer_snapshot,
1665                        new,
1666                        counts,
1667                        cx,
1668                    );
1669                    ranges
1670                })
1671                .ok()
1672                .unwrap_or_default()
1673        })
1674    }
1675
1676    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1677    fn set_merged_excerpt_ranges_for_path(
1678        &mut self,
1679        path: PathKey,
1680        buffer: Entity<Buffer>,
1681        ranges: Vec<ExcerptRange<Point>>,
1682        buffer_snapshot: &BufferSnapshot,
1683        new: Vec<ExcerptRange<Point>>,
1684        counts: Vec<usize>,
1685        cx: &mut Context<Self>,
1686    ) -> (Vec<Range<Anchor>>, bool) {
1687        let (excerpt_ids, added_a_new_excerpt) =
1688            self.update_path_excerpts(path, buffer, buffer_snapshot, new, cx);
1689
1690        let mut result = Vec::new();
1691        let mut ranges = ranges.into_iter();
1692        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(counts.into_iter()) {
1693            for range in ranges.by_ref().take(range_count) {
1694                let range = Anchor::range_in_buffer(
1695                    excerpt_id,
1696                    buffer_snapshot.remote_id(),
1697                    buffer_snapshot.anchor_before(&range.primary.start)
1698                        ..buffer_snapshot.anchor_after(&range.primary.end),
1699                );
1700                result.push(range)
1701            }
1702        }
1703        (result, added_a_new_excerpt)
1704    }
1705
1706    fn merge_excerpt_ranges<'a>(
1707        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1708    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1709        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1710        let mut counts: Vec<usize> = Vec::new();
1711        for range in expanded_ranges {
1712            if let Some(last_range) = merged_ranges.last_mut() {
1713                debug_assert!(
1714                    last_range.context.start <= range.context.start,
1715                    "Last range: {last_range:?} Range: {range:?}"
1716                );
1717                if last_range.context.end >= range.context.start
1718                    || last_range.context.end.row + 1 == range.context.start.row
1719                {
1720                    last_range.context.end = range.context.end.max(last_range.context.end);
1721                    *counts.last_mut().unwrap() += 1;
1722                    continue;
1723                }
1724            }
1725            merged_ranges.push(range.clone());
1726            counts.push(1);
1727        }
1728        (merged_ranges, counts)
1729    }
1730
1731    fn update_path_excerpts(
1732        &mut self,
1733        path: PathKey,
1734        buffer: Entity<Buffer>,
1735        buffer_snapshot: &BufferSnapshot,
1736        new: Vec<ExcerptRange<Point>>,
1737        cx: &mut Context<Self>,
1738    ) -> (Vec<ExcerptId>, bool) {
1739        let mut insert_after = self
1740            .excerpts_by_path
1741            .range(..path.clone())
1742            .next_back()
1743            .map(|(_, value)| *value.last().unwrap())
1744            .unwrap_or(ExcerptId::min());
1745
1746        let existing = self
1747            .excerpts_by_path
1748            .get(&path)
1749            .cloned()
1750            .unwrap_or_default();
1751
1752        let mut new_iter = new.into_iter().peekable();
1753        let mut existing_iter = existing.into_iter().peekable();
1754
1755        let mut excerpt_ids = Vec::new();
1756        let mut to_remove = Vec::new();
1757        let mut to_insert: Vec<(ExcerptId, ExcerptRange<Point>)> = Vec::new();
1758        let mut added_a_new_excerpt = false;
1759        let snapshot = self.snapshot(cx);
1760
1761        let mut next_excerpt_id =
1762            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1763                last_entry.id.0 + 1
1764            } else {
1765                1
1766            };
1767
1768        let mut next_excerpt_id = move || ExcerptId(post_inc(&mut next_excerpt_id));
1769
1770        let mut excerpts_cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1771        excerpts_cursor.next();
1772
1773        loop {
1774            let new = new_iter.peek();
1775            let existing = if let Some(existing_id) = existing_iter.peek() {
1776                let locator = snapshot.excerpt_locator_for_id(*existing_id);
1777                excerpts_cursor.seek_forward(&Some(locator), Bias::Left);
1778                if let Some(excerpt) = excerpts_cursor.item() {
1779                    if excerpt.buffer_id != buffer_snapshot.remote_id() {
1780                        to_remove.push(*existing_id);
1781                        existing_iter.next();
1782                        continue;
1783                    }
1784                    Some((
1785                        *existing_id,
1786                        excerpt.range.context.to_point(buffer_snapshot),
1787                    ))
1788                } else {
1789                    None
1790                }
1791            } else {
1792                None
1793            };
1794
1795            if let Some((last_id, last)) = to_insert.last_mut() {
1796                if let Some(new) = new
1797                    && last.context.end >= new.context.start
1798                {
1799                    last.context.end = last.context.end.max(new.context.end);
1800                    excerpt_ids.push(*last_id);
1801                    new_iter.next();
1802                    continue;
1803                }
1804                if let Some((existing_id, existing_range)) = &existing
1805                    && last.context.end >= existing_range.start
1806                {
1807                    last.context.end = last.context.end.max(existing_range.end);
1808                    to_remove.push(*existing_id);
1809                    self.snapshot
1810                        .borrow_mut()
1811                        .replaced_excerpts
1812                        .insert(*existing_id, *last_id);
1813                    existing_iter.next();
1814                    continue;
1815                }
1816            }
1817
1818            match (new, existing) {
1819                (None, None) => break,
1820                (None, Some((existing_id, _))) => {
1821                    existing_iter.next();
1822                    to_remove.push(existing_id);
1823                    continue;
1824                }
1825                (Some(_), None) => {
1826                    added_a_new_excerpt = true;
1827                    let new_id = next_excerpt_id();
1828                    excerpt_ids.push(new_id);
1829                    to_insert.push((new_id, new_iter.next().unwrap()));
1830                    continue;
1831                }
1832                (Some(new), Some((_, existing_range))) => {
1833                    if existing_range.end < new.context.start {
1834                        let existing_id = existing_iter.next().unwrap();
1835                        to_remove.push(existing_id);
1836                        continue;
1837                    } else if existing_range.start > new.context.end {
1838                        let new_id = next_excerpt_id();
1839                        excerpt_ids.push(new_id);
1840                        to_insert.push((new_id, new_iter.next().unwrap()));
1841                        continue;
1842                    }
1843
1844                    if existing_range.start == new.context.start
1845                        && existing_range.end == new.context.end
1846                    {
1847                        self.insert_excerpts_with_ids_after(
1848                            insert_after,
1849                            buffer.clone(),
1850                            mem::take(&mut to_insert),
1851                            cx,
1852                        );
1853                        insert_after = existing_iter.next().unwrap();
1854                        excerpt_ids.push(insert_after);
1855                        new_iter.next();
1856                    } else {
1857                        let existing_id = existing_iter.next().unwrap();
1858                        let new_id = next_excerpt_id();
1859                        self.snapshot
1860                            .borrow_mut()
1861                            .replaced_excerpts
1862                            .insert(existing_id, new_id);
1863                        to_remove.push(existing_id);
1864                        let mut range = new_iter.next().unwrap();
1865                        range.context.start = range.context.start.min(existing_range.start);
1866                        range.context.end = range.context.end.max(existing_range.end);
1867                        excerpt_ids.push(new_id);
1868                        to_insert.push((new_id, range));
1869                    }
1870                }
1871            };
1872        }
1873
1874        self.insert_excerpts_with_ids_after(insert_after, buffer, to_insert, cx);
1875        self.remove_excerpts(to_remove, cx);
1876        if excerpt_ids.is_empty() {
1877            self.excerpts_by_path.remove(&path);
1878        } else {
1879            for excerpt_id in &excerpt_ids {
1880                self.paths_by_excerpt.insert(*excerpt_id, path.clone());
1881            }
1882            self.excerpts_by_path
1883                .insert(path, excerpt_ids.iter().dedup().cloned().collect());
1884        }
1885
1886        (excerpt_ids, added_a_new_excerpt)
1887    }
1888
1889    pub fn paths(&self) -> impl Iterator<Item = PathKey> + '_ {
1890        self.excerpts_by_path.keys().cloned()
1891    }
1892
1893    pub fn remove_excerpts_for_path(&mut self, path: PathKey, cx: &mut Context<Self>) {
1894        if let Some(to_remove) = self.excerpts_by_path.remove(&path) {
1895            self.remove_excerpts(to_remove, cx)
1896        }
1897    }
1898
1899    pub fn insert_excerpts_after<O>(
1900        &mut self,
1901        prev_excerpt_id: ExcerptId,
1902        buffer: Entity<Buffer>,
1903        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1904        cx: &mut Context<Self>,
1905    ) -> Vec<ExcerptId>
1906    where
1907        O: text::ToOffset,
1908    {
1909        let mut ids = Vec::new();
1910        let mut next_excerpt_id =
1911            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1912                last_entry.id.0 + 1
1913            } else {
1914                1
1915            };
1916        self.insert_excerpts_with_ids_after(
1917            prev_excerpt_id,
1918            buffer,
1919            ranges.into_iter().map(|range| {
1920                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1921                ids.push(id);
1922                (id, range)
1923            }),
1924            cx,
1925        );
1926        ids
1927    }
1928
1929    pub fn insert_excerpts_with_ids_after<O>(
1930        &mut self,
1931        prev_excerpt_id: ExcerptId,
1932        buffer: Entity<Buffer>,
1933        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1934        cx: &mut Context<Self>,
1935    ) where
1936        O: text::ToOffset,
1937    {
1938        assert_eq!(self.history.transaction_depth, 0);
1939        let mut ranges = ranges.into_iter().peekable();
1940        if ranges.peek().is_none() {
1941            return Default::default();
1942        }
1943
1944        self.sync(cx);
1945
1946        let buffer_snapshot = buffer.read(cx).snapshot();
1947        let buffer_id = buffer_snapshot.remote_id();
1948
1949        let mut buffers = self.buffers.borrow_mut();
1950        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| {
1951            self.buffer_changed_since_sync.replace(true);
1952            buffer.update(cx, |buffer, _| {
1953                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1954            });
1955            BufferState {
1956                last_version: buffer_snapshot.version().clone(),
1957                last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1958                excerpts: Default::default(),
1959                _subscriptions: [
1960                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1961                    cx.subscribe(&buffer, Self::on_buffer_event),
1962                ],
1963                buffer: buffer.clone(),
1964            }
1965        });
1966
1967        let mut snapshot = self.snapshot.borrow_mut();
1968
1969        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1970        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1971        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1972        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1973        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1974
1975        let edit_start = ExcerptOffset::new(new_excerpts.summary().text.len);
1976        new_excerpts.update_last(
1977            |excerpt| {
1978                excerpt.has_trailing_newline = true;
1979            },
1980            &(),
1981        );
1982
1983        let next_locator = if let Some(excerpt) = cursor.item() {
1984            excerpt.locator.clone()
1985        } else {
1986            Locator::max()
1987        };
1988
1989        let mut excerpts = Vec::new();
1990        while let Some((id, range)) = ranges.next() {
1991            let locator = Locator::between(&prev_locator, &next_locator);
1992            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1993                buffer_state.excerpts.insert(ix, locator.clone());
1994            }
1995            let range = ExcerptRange {
1996                context: buffer_snapshot.anchor_before(&range.context.start)
1997                    ..buffer_snapshot.anchor_after(&range.context.end),
1998                primary: buffer_snapshot.anchor_before(&range.primary.start)
1999                    ..buffer_snapshot.anchor_after(&range.primary.end),
2000            };
2001            excerpts.push((id, range.clone()));
2002            let excerpt = Excerpt::new(
2003                id,
2004                locator.clone(),
2005                buffer_id,
2006                buffer_snapshot.clone(),
2007                range,
2008                ranges.peek().is_some() || cursor.item().is_some(),
2009            );
2010            new_excerpts.push(excerpt, &());
2011            prev_locator = locator.clone();
2012
2013            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
2014                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
2015            }
2016            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
2017        }
2018
2019        let edit_end = ExcerptOffset::new(new_excerpts.summary().text.len);
2020
2021        let suffix = cursor.suffix();
2022        let changed_trailing_excerpt = suffix.is_empty();
2023        new_excerpts.append(suffix, &());
2024        drop(cursor);
2025        snapshot.excerpts = new_excerpts;
2026        snapshot.excerpt_ids = new_excerpt_ids;
2027        if changed_trailing_excerpt {
2028            snapshot.trailing_excerpt_update_count += 1;
2029        }
2030
2031        self.sync_diff_transforms(
2032            &mut snapshot,
2033            vec![Edit {
2034                old: edit_start..edit_start,
2035                new: edit_start..edit_end,
2036            }],
2037            DiffChangeKind::BufferEdited,
2038        );
2039        cx.emit(Event::Edited {
2040            singleton_buffer_edited: false,
2041            edited_buffer: None,
2042        });
2043        cx.emit(Event::ExcerptsAdded {
2044            buffer,
2045            predecessor: prev_excerpt_id,
2046            excerpts,
2047        });
2048        cx.notify();
2049    }
2050
2051    pub fn clear(&mut self, cx: &mut Context<Self>) {
2052        self.sync(cx);
2053        let ids = self.excerpt_ids();
2054        let removed_buffer_ids = self
2055            .buffers
2056            .borrow_mut()
2057            .drain()
2058            .map(|(id, _)| id)
2059            .collect();
2060        self.excerpts_by_path.clear();
2061        self.paths_by_excerpt.clear();
2062        let mut snapshot = self.snapshot.borrow_mut();
2063        let start = ExcerptOffset::new(0);
2064        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2065        snapshot.excerpts = Default::default();
2066        snapshot.trailing_excerpt_update_count += 1;
2067        snapshot.is_dirty = false;
2068        snapshot.has_deleted_file = false;
2069        snapshot.has_conflict = false;
2070        snapshot.replaced_excerpts.clear();
2071
2072        self.sync_diff_transforms(
2073            &mut snapshot,
2074            vec![Edit {
2075                old: start..prev_len,
2076                new: start..start,
2077            }],
2078            DiffChangeKind::BufferEdited,
2079        );
2080        cx.emit(Event::Edited {
2081            singleton_buffer_edited: false,
2082            edited_buffer: None,
2083        });
2084        cx.emit(Event::ExcerptsRemoved {
2085            ids,
2086            removed_buffer_ids,
2087        });
2088        cx.notify();
2089    }
2090
2091    pub fn excerpts_for_buffer(
2092        &self,
2093        buffer_id: BufferId,
2094        cx: &App,
2095    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2096        let mut excerpts = Vec::new();
2097        let snapshot = self.read(cx);
2098        let buffers = self.buffers.borrow();
2099        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
2100        for locator in buffers
2101            .get(&buffer_id)
2102            .map(|state| &state.excerpts)
2103            .into_iter()
2104            .flatten()
2105        {
2106            cursor.seek_forward(&Some(locator), Bias::Left);
2107            if let Some(excerpt) = cursor.item()
2108                && excerpt.locator == *locator
2109            {
2110                excerpts.push((excerpt.id, excerpt.range.clone()));
2111            }
2112        }
2113
2114        excerpts
2115    }
2116
2117    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2118        let snapshot = self.read(cx);
2119        let buffers = self.buffers.borrow();
2120        let mut excerpts = snapshot
2121            .excerpts
2122            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(&());
2123        let mut diff_transforms = snapshot
2124            .diff_transforms
2125            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(&());
2126        diff_transforms.next();
2127        let locators = buffers
2128            .get(&buffer_id)
2129            .into_iter()
2130            .flat_map(|state| &state.excerpts);
2131        let mut result = Vec::new();
2132        for locator in locators {
2133            excerpts.seek_forward(&Some(locator), Bias::Left);
2134            if let Some(excerpt) = excerpts.item()
2135                && excerpt.locator == *locator
2136            {
2137                let excerpt_start = excerpts.start().1.clone();
2138                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2139
2140                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2141                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2142                let start = diff_transforms.start().1.0 + overshoot;
2143
2144                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2145                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2146                let end = diff_transforms.start().1.0 + overshoot;
2147
2148                result.push(start..end)
2149            }
2150        }
2151        result
2152    }
2153
2154    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2155        self.snapshot
2156            .borrow()
2157            .excerpts
2158            .iter()
2159            .map(|entry| entry.buffer_id)
2160            .collect()
2161    }
2162
2163    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2164        self.snapshot
2165            .borrow()
2166            .excerpts
2167            .iter()
2168            .map(|entry| entry.id)
2169            .collect()
2170    }
2171
2172    pub fn excerpt_containing(
2173        &self,
2174        position: impl ToOffset,
2175        cx: &App,
2176    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2177        let snapshot = self.read(cx);
2178        let offset = position.to_offset(&snapshot);
2179
2180        let mut cursor = snapshot.cursor::<usize>();
2181        cursor.seek(&offset);
2182        cursor
2183            .excerpt()
2184            .or_else(|| snapshot.excerpts.last())
2185            .map(|excerpt| {
2186                (
2187                    excerpt.id,
2188                    self.buffers
2189                        .borrow()
2190                        .get(&excerpt.buffer_id)
2191                        .unwrap()
2192                        .buffer
2193                        .clone(),
2194                    excerpt.range.context.clone(),
2195                )
2196            })
2197    }
2198
2199    // If point is at the end of the buffer, the last excerpt is returned
2200    pub fn point_to_buffer_offset<T: ToOffset>(
2201        &self,
2202        point: T,
2203        cx: &App,
2204    ) -> Option<(Entity<Buffer>, usize)> {
2205        let snapshot = self.read(cx);
2206        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2207        Some((
2208            self.buffers
2209                .borrow()
2210                .get(&buffer.remote_id())?
2211                .buffer
2212                .clone(),
2213            offset,
2214        ))
2215    }
2216
2217    // If point is at the end of the buffer, the last excerpt is returned
2218    pub fn point_to_buffer_point<T: ToPoint>(
2219        &self,
2220        point: T,
2221        cx: &App,
2222    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2223        let snapshot = self.read(cx);
2224        let (buffer, point, is_main_buffer) =
2225            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2226        Some((
2227            self.buffers
2228                .borrow()
2229                .get(&buffer.remote_id())?
2230                .buffer
2231                .clone(),
2232            point,
2233            is_main_buffer,
2234        ))
2235    }
2236
2237    pub fn buffer_point_to_anchor(
2238        &self,
2239        buffer: &Entity<Buffer>,
2240        point: Point,
2241        cx: &App,
2242    ) -> Option<Anchor> {
2243        let mut found = None;
2244        let snapshot = buffer.read(cx).snapshot();
2245        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2246            let start = range.context.start.to_point(&snapshot);
2247            let end = range.context.end.to_point(&snapshot);
2248            if start <= point && point < end {
2249                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2250                break;
2251            }
2252            if point < start {
2253                found = Some((start, excerpt_id));
2254            }
2255            if point > end {
2256                found = Some((end, excerpt_id));
2257            }
2258        }
2259
2260        found.map(|(point, excerpt_id)| {
2261            let text_anchor = snapshot.anchor_after(point);
2262            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2263        })
2264    }
2265
2266    pub fn remove_excerpts(
2267        &mut self,
2268        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2269        cx: &mut Context<Self>,
2270    ) {
2271        self.sync(cx);
2272        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2273        if ids.is_empty() {
2274            return;
2275        }
2276
2277        let mut buffers = self.buffers.borrow_mut();
2278        let mut snapshot = self.snapshot.borrow_mut();
2279        let mut new_excerpts = SumTree::default();
2280        let mut cursor = snapshot
2281            .excerpts
2282            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
2283        let mut edits = Vec::new();
2284        let mut excerpt_ids = ids.iter().copied().peekable();
2285        let mut removed_buffer_ids = Vec::new();
2286
2287        while let Some(excerpt_id) = excerpt_ids.next() {
2288            self.paths_by_excerpt.remove(&excerpt_id);
2289            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2290            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2291            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), &());
2292
2293            if let Some(mut excerpt) = cursor.item() {
2294                if excerpt.id != excerpt_id {
2295                    continue;
2296                }
2297                let mut old_start = cursor.start().1;
2298
2299                // Skip over the removed excerpt.
2300                'remove_excerpts: loop {
2301                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2302                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2303                        if buffer_state.excerpts.is_empty() {
2304                            log::debug!(
2305                                "removing buffer and diff for buffer {}",
2306                                excerpt.buffer_id
2307                            );
2308                            buffers.remove(&excerpt.buffer_id);
2309                            removed_buffer_ids.push(excerpt.buffer_id);
2310                        }
2311                    }
2312                    cursor.next();
2313
2314                    // Skip over any subsequent excerpts that are also removed.
2315                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2316                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2317                        if let Some(next_excerpt) = cursor.item()
2318                            && next_excerpt.locator == *next_locator
2319                        {
2320                            excerpt_ids.next();
2321                            excerpt = next_excerpt;
2322                            continue 'remove_excerpts;
2323                        }
2324                    }
2325
2326                    break;
2327                }
2328
2329                // When removing the last excerpt, remove the trailing newline from
2330                // the previous excerpt.
2331                if cursor.item().is_none() && old_start.value > 0 {
2332                    old_start.value -= 1;
2333                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
2334                }
2335
2336                // Push an edit for the removal of this run of excerpts.
2337                let old_end = cursor.start().1;
2338                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2339                edits.push(Edit {
2340                    old: old_start..old_end,
2341                    new: new_start..new_start,
2342                });
2343            }
2344        }
2345        let suffix = cursor.suffix();
2346        let changed_trailing_excerpt = suffix.is_empty();
2347        new_excerpts.append(suffix, &());
2348        drop(cursor);
2349        snapshot.excerpts = new_excerpts;
2350        for buffer_id in &removed_buffer_ids {
2351            self.diffs.remove(buffer_id);
2352            snapshot.diffs.remove(buffer_id);
2353        }
2354
2355        if changed_trailing_excerpt {
2356            snapshot.trailing_excerpt_update_count += 1;
2357        }
2358
2359        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2360        self.buffer_changed_since_sync.replace(true);
2361        cx.emit(Event::Edited {
2362            singleton_buffer_edited: false,
2363            edited_buffer: None,
2364        });
2365        cx.emit(Event::ExcerptsRemoved {
2366            ids,
2367            removed_buffer_ids,
2368        });
2369        cx.notify();
2370    }
2371
2372    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2373        &self,
2374        anchors: Anchors,
2375        cx: &mut Context<Self>,
2376    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2377        let borrow = self.buffers.borrow();
2378        let mut error = None;
2379        let mut futures = Vec::new();
2380        for anchor in anchors {
2381            if let Some(buffer_id) = anchor.buffer_id {
2382                if let Some(buffer) = borrow.get(&buffer_id) {
2383                    buffer.buffer.update(cx, |buffer, _| {
2384                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2385                    });
2386                } else {
2387                    error = Some(anyhow!(
2388                        "buffer {buffer_id} is not part of this multi-buffer"
2389                    ));
2390                    break;
2391                }
2392            }
2393        }
2394        async move {
2395            if let Some(error) = error {
2396                Err(error)?;
2397            }
2398            for future in futures {
2399                future.await?;
2400            }
2401            Ok(())
2402        }
2403    }
2404
2405    pub fn text_anchor_for_position<T: ToOffset>(
2406        &self,
2407        position: T,
2408        cx: &App,
2409    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2410        let snapshot = self.read(cx);
2411        let anchor = snapshot.anchor_before(position);
2412        let buffer = self
2413            .buffers
2414            .borrow()
2415            .get(&anchor.buffer_id?)?
2416            .buffer
2417            .clone();
2418        Some((buffer, anchor.text_anchor))
2419    }
2420
2421    fn on_buffer_event(
2422        &mut self,
2423        buffer: Entity<Buffer>,
2424        event: &language::BufferEvent,
2425        cx: &mut Context<Self>,
2426    ) {
2427        cx.emit(match event {
2428            language::BufferEvent::Edited => Event::Edited {
2429                singleton_buffer_edited: true,
2430                edited_buffer: Some(buffer),
2431            },
2432            language::BufferEvent::DirtyChanged => Event::DirtyChanged,
2433            language::BufferEvent::Saved => Event::Saved,
2434            language::BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2435            language::BufferEvent::Reloaded => Event::Reloaded,
2436            language::BufferEvent::ReloadNeeded => Event::ReloadNeeded,
2437            language::BufferEvent::LanguageChanged => {
2438                Event::LanguageChanged(buffer.read(cx).remote_id())
2439            }
2440            language::BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2441            language::BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2442            language::BufferEvent::Closed => Event::Closed,
2443            language::BufferEvent::Discarded => Event::Discarded,
2444            language::BufferEvent::CapabilityChanged => {
2445                self.capability = buffer.read(cx).capability();
2446                Event::CapabilityChanged
2447            }
2448            language::BufferEvent::Operation { .. } => return,
2449        });
2450    }
2451
2452    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2453        self.sync(cx);
2454        let mut snapshot = self.snapshot.borrow_mut();
2455        let diff = diff.read(cx);
2456        let buffer_id = diff.buffer_id;
2457        let diff = diff.snapshot(cx);
2458        snapshot.diffs.insert(buffer_id, diff);
2459    }
2460
2461    fn buffer_diff_changed(
2462        &mut self,
2463        diff: Entity<BufferDiff>,
2464        range: Range<text::Anchor>,
2465        cx: &mut Context<Self>,
2466    ) {
2467        self.sync(cx);
2468        self.buffer_changed_since_sync.replace(true);
2469
2470        let diff = diff.read(cx);
2471        let buffer_id = diff.buffer_id;
2472        let buffers = self.buffers.borrow();
2473        let Some(buffer_state) = 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 new_diff = diff.snapshot(cx);
2481        let mut snapshot = self.snapshot.borrow_mut();
2482        let base_text_changed = snapshot
2483            .diffs
2484            .get(&buffer_id)
2485            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2486
2487        snapshot.diffs.insert(buffer_id, new_diff);
2488
2489        let mut excerpt_edits = Vec::new();
2490        for locator in &buffer_state.excerpts {
2491            let mut cursor = snapshot
2492                .excerpts
2493                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
2494            cursor.seek_forward(&Some(locator), Bias::Left);
2495            if let Some(excerpt) = cursor.item()
2496                && excerpt.locator == *locator
2497            {
2498                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2499                if diff_change_range.end < excerpt_buffer_range.start
2500                    || diff_change_range.start > excerpt_buffer_range.end
2501                {
2502                    continue;
2503                }
2504                let excerpt_start = cursor.start().1;
2505                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2506                let diff_change_start_in_excerpt = ExcerptOffset::new(
2507                    diff_change_range
2508                        .start
2509                        .saturating_sub(excerpt_buffer_range.start),
2510                );
2511                let diff_change_end_in_excerpt = ExcerptOffset::new(
2512                    diff_change_range
2513                        .end
2514                        .saturating_sub(excerpt_buffer_range.start),
2515                );
2516                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2517                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2518                excerpt_edits.push(Edit {
2519                    old: edit_start..edit_end,
2520                    new: edit_start..edit_end,
2521                });
2522            }
2523        }
2524
2525        self.sync_diff_transforms(
2526            &mut snapshot,
2527            excerpt_edits,
2528            DiffChangeKind::DiffUpdated {
2529                base_changed: base_text_changed,
2530            },
2531        );
2532        cx.emit(Event::Edited {
2533            singleton_buffer_edited: false,
2534            edited_buffer: None,
2535        });
2536    }
2537
2538    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2539        self.buffers
2540            .borrow()
2541            .values()
2542            .map(|state| state.buffer.clone())
2543            .collect()
2544    }
2545
2546    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2547        self.buffers
2548            .borrow()
2549            .get(&buffer_id)
2550            .map(|state| state.buffer.clone())
2551    }
2552
2553    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2554        self.point_to_buffer_offset(point, cx)
2555            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2556    }
2557
2558    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2559        let buffer_id = self
2560            .snapshot
2561            .borrow()
2562            .excerpts
2563            .first()
2564            .map(|excerpt| excerpt.buffer.remote_id());
2565        buffer_id
2566            .and_then(|buffer_id| self.buffer(buffer_id))
2567            .map(|buffer| {
2568                let buffer = buffer.read(cx);
2569                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2570            })
2571            .unwrap_or_else(move || self.language_settings_at(0, cx))
2572    }
2573
2574    pub fn language_settings_at<'a, T: ToOffset>(
2575        &'a self,
2576        point: T,
2577        cx: &'a App,
2578    ) -> Cow<'a, LanguageSettings> {
2579        let mut language = None;
2580        let mut file = None;
2581        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2582            let buffer = buffer.read(cx);
2583            language = buffer.language_at(offset);
2584            file = buffer.file();
2585        }
2586        language_settings(language.map(|l| l.name()), file, cx)
2587    }
2588
2589    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2590        self.buffers
2591            .borrow()
2592            .values()
2593            .for_each(|state| f(&state.buffer))
2594    }
2595
2596    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2597        if let Some(title) = self.title.as_ref() {
2598            return title.into();
2599        }
2600
2601        if let Some(buffer) = self.as_singleton() {
2602            let buffer = buffer.read(cx);
2603
2604            if let Some(file) = buffer.file() {
2605                return file.file_name(cx).to_string_lossy();
2606            }
2607
2608            if let Some(title) = self.buffer_content_title(buffer) {
2609                return title;
2610            }
2611        };
2612
2613        "untitled".into()
2614    }
2615
2616    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2617        let mut is_leading_whitespace = true;
2618        let mut count = 0;
2619        let mut prev_was_space = false;
2620        let mut title = String::new();
2621
2622        for ch in buffer.snapshot().chars() {
2623            if is_leading_whitespace && ch.is_whitespace() {
2624                continue;
2625            }
2626
2627            is_leading_whitespace = false;
2628
2629            if ch == '\n' || count >= 40 {
2630                break;
2631            }
2632
2633            if ch.is_whitespace() {
2634                if !prev_was_space {
2635                    title.push(' ');
2636                    count += 1;
2637                    prev_was_space = true;
2638                }
2639            } else {
2640                title.push(ch);
2641                count += 1;
2642                prev_was_space = false;
2643            }
2644        }
2645
2646        let title = title.trim_end().to_string();
2647
2648        if title.is_empty() {
2649            return None;
2650        }
2651
2652        Some(title.into())
2653    }
2654
2655    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2656        self.title = Some(title);
2657        cx.notify();
2658    }
2659
2660    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2661    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2662        for buffer_state in self.buffers.borrow().values() {
2663            buffer_state
2664                .buffer
2665                .update(cx, |buffer, _cx| buffer.refresh_preview());
2666        }
2667    }
2668
2669    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2670    pub fn preserve_preview(&self, cx: &App) -> bool {
2671        self.buffers
2672            .borrow()
2673            .values()
2674            .all(|state| state.buffer.read(cx).preserve_preview())
2675    }
2676
2677    #[cfg(any(test, feature = "test-support"))]
2678    pub fn is_parsing(&self, cx: &App) -> bool {
2679        self.as_singleton().unwrap().read(cx).is_parsing()
2680    }
2681
2682    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2683        let buffer_id = diff.read(cx).buffer_id;
2684        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2685        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2686    }
2687
2688    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2689        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2690    }
2691
2692    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2693        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2694    }
2695
2696    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2697        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2698    }
2699
2700    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2701        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2702        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2703    }
2704
2705    pub fn all_diff_hunks_expanded(&self) -> bool {
2706        self.snapshot.borrow().all_diff_hunks_expanded
2707    }
2708
2709    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2710        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2711        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2712    }
2713
2714    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2715        self.read(cx)
2716            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2717            .nth(1)
2718            .is_some()
2719    }
2720
2721    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2722        let snapshot = self.read(cx);
2723        let mut cursor = snapshot.diff_transforms.cursor::<usize>(&());
2724        let offset_range = range.to_offset(&snapshot);
2725        cursor.seek(&offset_range.start, Bias::Left);
2726        while let Some(item) = cursor.item() {
2727            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2728                break;
2729            }
2730            if item.hunk_info().is_some() {
2731                return true;
2732            }
2733            cursor.next();
2734        }
2735        false
2736    }
2737
2738    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2739        let snapshot = self.read(cx);
2740        let mut cursor = snapshot.diff_transforms.cursor::<usize>(&());
2741        for range in ranges {
2742            let range = range.to_point(&snapshot);
2743            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2744            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2745            let start = start.saturating_sub(1);
2746            let end = snapshot.len().min(end + 1);
2747            cursor.seek(&start, Bias::Right);
2748            while let Some(item) = cursor.item() {
2749                if *cursor.start() >= end {
2750                    break;
2751                }
2752                if item.hunk_info().is_some() {
2753                    return true;
2754                }
2755                cursor.next();
2756            }
2757        }
2758        false
2759    }
2760
2761    pub fn expand_or_collapse_diff_hunks_inner(
2762        &mut self,
2763        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2764        expand: bool,
2765        cx: &mut Context<Self>,
2766    ) {
2767        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2768            return;
2769        }
2770        self.sync(cx);
2771        let mut snapshot = self.snapshot.borrow_mut();
2772        let mut excerpt_edits = Vec::new();
2773        let mut last_hunk_row = None;
2774        for (range, end_excerpt_id) in ranges {
2775            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2776                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2777                    continue;
2778                }
2779                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2780                    continue;
2781                }
2782                let start = Anchor::in_buffer(
2783                    diff_hunk.excerpt_id,
2784                    diff_hunk.buffer_id,
2785                    diff_hunk.buffer_range.start,
2786                );
2787                let end = Anchor::in_buffer(
2788                    diff_hunk.excerpt_id,
2789                    diff_hunk.buffer_id,
2790                    diff_hunk.buffer_range.end,
2791                );
2792                let start = snapshot.excerpt_offset_for_anchor(&start);
2793                let end = snapshot.excerpt_offset_for_anchor(&end);
2794                last_hunk_row = Some(diff_hunk.row_range.start);
2795                excerpt_edits.push(text::Edit {
2796                    old: start..end,
2797                    new: start..end,
2798                });
2799            }
2800        }
2801
2802        self.sync_diff_transforms(
2803            &mut snapshot,
2804            excerpt_edits,
2805            DiffChangeKind::ExpandOrCollapseHunks { expand },
2806        );
2807        cx.emit(Event::DiffHunksToggled);
2808        cx.emit(Event::Edited {
2809            singleton_buffer_edited: false,
2810            edited_buffer: None,
2811        });
2812    }
2813
2814    pub fn expand_or_collapse_diff_hunks(
2815        &mut self,
2816        ranges: Vec<Range<Anchor>>,
2817        expand: bool,
2818        cx: &mut Context<Self>,
2819    ) {
2820        let snapshot = self.snapshot.borrow().clone();
2821        let ranges = ranges.iter().map(move |range| {
2822            let end_excerpt_id = range.end.excerpt_id;
2823            let range = range.to_point(&snapshot);
2824            let mut peek_end = range.end;
2825            if range.end.row < snapshot.max_row().0 {
2826                peek_end = Point::new(range.end.row + 1, 0);
2827            };
2828            (range.start..peek_end, end_excerpt_id)
2829        });
2830        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2831    }
2832
2833    pub fn resize_excerpt(
2834        &mut self,
2835        id: ExcerptId,
2836        range: Range<text::Anchor>,
2837        cx: &mut Context<Self>,
2838    ) {
2839        self.sync(cx);
2840
2841        let mut snapshot = self.snapshot.borrow_mut();
2842        let locator = snapshot.excerpt_locator_for_id(id);
2843        let mut new_excerpts = SumTree::default();
2844        let mut cursor = snapshot
2845            .excerpts
2846            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
2847        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2848
2849        let prefix = cursor.slice(&Some(locator), Bias::Left);
2850        new_excerpts.append(prefix, &());
2851
2852        let mut excerpt = cursor.item().unwrap().clone();
2853        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2854
2855        excerpt.range.context.start = range.start;
2856        excerpt.range.context.end = range.end;
2857        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2858
2859        excerpt.text_summary = excerpt
2860            .buffer
2861            .text_summary_for_range(excerpt.range.context.clone());
2862
2863        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2864        let old_start_offset = cursor.start().1;
2865        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2866        let edit = Edit {
2867            old: old_start_offset..old_start_offset + old_text_len,
2868            new: new_start_offset..new_start_offset + new_text_len,
2869        };
2870
2871        if let Some(last_edit) = edits.last_mut() {
2872            if last_edit.old.end == edit.old.start {
2873                last_edit.old.end = edit.old.end;
2874                last_edit.new.end = edit.new.end;
2875            } else {
2876                edits.push(edit);
2877            }
2878        } else {
2879            edits.push(edit);
2880        }
2881
2882        new_excerpts.push(excerpt, &());
2883
2884        cursor.next();
2885
2886        new_excerpts.append(cursor.suffix(), &());
2887
2888        drop(cursor);
2889        snapshot.excerpts = new_excerpts;
2890
2891        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2892        cx.emit(Event::Edited {
2893            singleton_buffer_edited: false,
2894            edited_buffer: None,
2895        });
2896        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2897        cx.notify();
2898    }
2899
2900    pub fn expand_excerpts(
2901        &mut self,
2902        ids: impl IntoIterator<Item = ExcerptId>,
2903        line_count: u32,
2904        direction: ExpandExcerptDirection,
2905        cx: &mut Context<Self>,
2906    ) {
2907        if line_count == 0 {
2908            return;
2909        }
2910        self.sync(cx);
2911        if !self.excerpts_by_path.is_empty() {
2912            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2913            return;
2914        }
2915        let mut snapshot = self.snapshot.borrow_mut();
2916
2917        let ids = ids.into_iter().collect::<Vec<_>>();
2918        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2919        let mut new_excerpts = SumTree::default();
2920        let mut cursor = snapshot
2921            .excerpts
2922            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
2923        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2924
2925        for locator in &locators {
2926            let prefix = cursor.slice(&Some(locator), Bias::Left);
2927            new_excerpts.append(prefix, &());
2928
2929            let mut excerpt = cursor.item().unwrap().clone();
2930            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2931
2932            let up_line_count = if direction.should_expand_up() {
2933                line_count
2934            } else {
2935                0
2936            };
2937
2938            let start_row = excerpt
2939                .range
2940                .context
2941                .start
2942                .to_point(&excerpt.buffer)
2943                .row
2944                .saturating_sub(up_line_count);
2945            let start_point = Point::new(start_row, 0);
2946            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2947
2948            let down_line_count = if direction.should_expand_down() {
2949                line_count
2950            } else {
2951                0
2952            };
2953
2954            let mut end_point = excerpt.buffer.clip_point(
2955                excerpt.range.context.end.to_point(&excerpt.buffer)
2956                    + Point::new(down_line_count, 0),
2957                Bias::Left,
2958            );
2959            end_point.column = excerpt.buffer.line_len(end_point.row);
2960            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2961            excerpt.max_buffer_row = end_point.row;
2962
2963            excerpt.text_summary = excerpt
2964                .buffer
2965                .text_summary_for_range(excerpt.range.context.clone());
2966
2967            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2968            let old_start_offset = cursor.start().1;
2969            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2970            let edit = Edit {
2971                old: old_start_offset..old_start_offset + old_text_len,
2972                new: new_start_offset..new_start_offset + new_text_len,
2973            };
2974
2975            if let Some(last_edit) = edits.last_mut() {
2976                if last_edit.old.end == edit.old.start {
2977                    last_edit.old.end = edit.old.end;
2978                    last_edit.new.end = edit.new.end;
2979                } else {
2980                    edits.push(edit);
2981                }
2982            } else {
2983                edits.push(edit);
2984            }
2985
2986            new_excerpts.push(excerpt, &());
2987
2988            cursor.next();
2989        }
2990
2991        new_excerpts.append(cursor.suffix(), &());
2992
2993        drop(cursor);
2994        snapshot.excerpts = new_excerpts;
2995
2996        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2997        cx.emit(Event::Edited {
2998            singleton_buffer_edited: false,
2999            edited_buffer: None,
3000        });
3001        cx.emit(Event::ExcerptsExpanded { ids });
3002        cx.notify();
3003    }
3004
3005    fn sync(&self, cx: &App) {
3006        let changed = self.buffer_changed_since_sync.replace(false);
3007        if !changed {
3008            return;
3009        }
3010
3011        let mut snapshot = self.snapshot.borrow_mut();
3012        let mut excerpts_to_edit = Vec::new();
3013        let mut non_text_state_updated = false;
3014        let mut is_dirty = false;
3015        let mut has_deleted_file = false;
3016        let mut has_conflict = false;
3017        let mut edited = false;
3018        let mut buffers = self.buffers.borrow_mut();
3019        for buffer_state in buffers.values_mut() {
3020            let buffer = buffer_state.buffer.read(cx);
3021            let version = buffer.version();
3022            let non_text_state_update_count = buffer.non_text_state_update_count();
3023
3024            let buffer_edited = version.changed_since(&buffer_state.last_version);
3025            let buffer_non_text_state_updated =
3026                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3027            if buffer_edited || buffer_non_text_state_updated {
3028                buffer_state.last_version = version;
3029                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3030                excerpts_to_edit.extend(
3031                    buffer_state
3032                        .excerpts
3033                        .iter()
3034                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3035                );
3036            }
3037
3038            edited |= buffer_edited;
3039            non_text_state_updated |= buffer_non_text_state_updated;
3040            is_dirty |= buffer.is_dirty();
3041            has_deleted_file |= buffer
3042                .file()
3043                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3044            has_conflict |= buffer.has_conflict();
3045        }
3046        if edited {
3047            snapshot.edit_count += 1;
3048        }
3049        if non_text_state_updated {
3050            snapshot.non_text_state_update_count += 1;
3051        }
3052        snapshot.is_dirty = is_dirty;
3053        snapshot.has_deleted_file = has_deleted_file;
3054        snapshot.has_conflict = has_conflict;
3055
3056        for (id, diff) in self.diffs.iter() {
3057            if snapshot.diffs.get(id).is_none() {
3058                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3059            }
3060        }
3061
3062        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3063
3064        let mut edits = Vec::new();
3065        let mut new_excerpts = SumTree::default();
3066        let mut cursor = snapshot
3067            .excerpts
3068            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
3069
3070        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3071            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), &());
3072            let old_excerpt = cursor.item().unwrap();
3073            let buffer = buffer.read(cx);
3074            let buffer_id = buffer.remote_id();
3075
3076            let mut new_excerpt;
3077            if buffer_edited {
3078                edits.extend(
3079                    buffer
3080                        .edits_since_in_range::<usize>(
3081                            old_excerpt.buffer.version(),
3082                            old_excerpt.range.context.clone(),
3083                        )
3084                        .map(|edit| {
3085                            let excerpt_old_start = cursor.start().1;
3086                            let excerpt_new_start =
3087                                ExcerptOffset::new(new_excerpts.summary().text.len);
3088                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3089                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3090                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3091                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3092                            Edit {
3093                                old: old_start..old_end,
3094                                new: new_start..new_end,
3095                            }
3096                        }),
3097                );
3098
3099                new_excerpt = Excerpt::new(
3100                    old_excerpt.id,
3101                    locator.clone(),
3102                    buffer_id,
3103                    buffer.snapshot(),
3104                    old_excerpt.range.clone(),
3105                    old_excerpt.has_trailing_newline,
3106                );
3107            } else {
3108                new_excerpt = old_excerpt.clone();
3109                new_excerpt.buffer = buffer.snapshot();
3110            }
3111
3112            new_excerpts.push(new_excerpt, &());
3113            cursor.next();
3114        }
3115        new_excerpts.append(cursor.suffix(), &());
3116
3117        drop(cursor);
3118        snapshot.excerpts = new_excerpts;
3119
3120        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3121    }
3122
3123    fn sync_diff_transforms(
3124        &self,
3125        snapshot: &mut MultiBufferSnapshot,
3126        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3127        change_kind: DiffChangeKind,
3128    ) {
3129        if excerpt_edits.is_empty() {
3130            return;
3131        }
3132
3133        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(&());
3134        let mut old_diff_transforms = snapshot
3135            .diff_transforms
3136            .cursor::<Dimensions<ExcerptOffset, usize>>(&());
3137        let mut new_diff_transforms = SumTree::default();
3138        let mut old_expanded_hunks = HashSet::default();
3139        let mut output_edits = Vec::new();
3140        let mut output_delta = 0_isize;
3141        let mut at_transform_boundary = true;
3142        let mut end_of_current_insert = None;
3143
3144        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3145        while let Some(edit) = excerpt_edits.next() {
3146            excerpts.seek_forward(&edit.new.start, Bias::Right);
3147            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3148                excerpts.prev();
3149            }
3150
3151            // Keep any transforms that are before the edit.
3152            if at_transform_boundary {
3153                at_transform_boundary = false;
3154                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3155                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3156                if let Some(transform) = old_diff_transforms.item()
3157                    && old_diff_transforms.end().0 == edit.old.start
3158                    && old_diff_transforms.start().0 < edit.old.start
3159                {
3160                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3161                    old_diff_transforms.next();
3162                }
3163            }
3164
3165            // Compute the start of the edit in output coordinates.
3166            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3167            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3168            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3169
3170            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3171                &edit,
3172                &mut excerpts,
3173                &mut old_diff_transforms,
3174                &mut new_diff_transforms,
3175                &mut end_of_current_insert,
3176                &mut old_expanded_hunks,
3177                snapshot,
3178                change_kind,
3179            );
3180
3181            // Compute the end of the edit in output coordinates.
3182            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3183            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3184            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3185            let edit_new_end =
3186                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3187            let output_edit = Edit {
3188                old: edit_old_start..edit_old_end,
3189                new: edit_new_start..edit_new_end,
3190            };
3191
3192            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3193            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3194            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3195                output_edits.push(output_edit);
3196            }
3197
3198            // If this is the last edit that intersects the current diff transform,
3199            // then recreate the content up to the end of this transform, to prepare
3200            // for reusing additional slices of the old transforms.
3201            if excerpt_edits
3202                .peek()
3203                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3204            {
3205                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3206                    && match old_diff_transforms.item() {
3207                        Some(DiffTransform::BufferContent {
3208                            inserted_hunk_info: Some(hunk),
3209                            ..
3210                        }) => excerpts.item().is_some_and(|excerpt| {
3211                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3212                        }),
3213                        _ => true,
3214                    };
3215
3216                let mut excerpt_offset = edit.new.end;
3217                if !keep_next_old_transform {
3218                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3219                    old_diff_transforms.next();
3220                }
3221
3222                old_expanded_hunks.clear();
3223                self.push_buffer_content_transform(
3224                    snapshot,
3225                    &mut new_diff_transforms,
3226                    excerpt_offset,
3227                    end_of_current_insert,
3228                );
3229                at_transform_boundary = true;
3230            }
3231        }
3232
3233        // Keep any transforms that are after the last edit.
3234        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3235
3236        // Ensure there's always at least one buffer content transform.
3237        if new_diff_transforms.is_empty() {
3238            new_diff_transforms.push(
3239                DiffTransform::BufferContent {
3240                    summary: Default::default(),
3241                    inserted_hunk_info: None,
3242                },
3243                &(),
3244            );
3245        }
3246
3247        self.subscriptions.publish(output_edits);
3248        drop(old_diff_transforms);
3249        drop(excerpts);
3250        snapshot.diff_transforms = new_diff_transforms;
3251        snapshot.edit_count += 1;
3252
3253        #[cfg(any(test, feature = "test-support"))]
3254        snapshot.check_invariants();
3255    }
3256
3257    fn recompute_diff_transforms_for_edit(
3258        &self,
3259        edit: &Edit<TypedOffset<Excerpt>>,
3260        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3261        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3262        new_diff_transforms: &mut SumTree<DiffTransform>,
3263        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3264        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3265        snapshot: &MultiBufferSnapshot,
3266        change_kind: DiffChangeKind,
3267    ) -> bool {
3268        log::trace!(
3269            "recomputing diff transform for edit {:?} => {:?}",
3270            edit.old.start.value..edit.old.end.value,
3271            edit.new.start.value..edit.new.end.value
3272        );
3273
3274        // Record which hunks were previously expanded.
3275        while let Some(item) = old_diff_transforms.item() {
3276            if let Some(hunk_info) = item.hunk_info() {
3277                log::trace!(
3278                    "previously expanded hunk at {}",
3279                    old_diff_transforms.start().0
3280                );
3281                old_expanded_hunks.insert(hunk_info);
3282            }
3283            if old_diff_transforms.end().0 > edit.old.end {
3284                break;
3285            }
3286            old_diff_transforms.next();
3287        }
3288
3289        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3290        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3291        if old_expanded_hunks.is_empty()
3292            && change_kind == DiffChangeKind::BufferEdited
3293            && !all_diff_hunks_expanded
3294        {
3295            return false;
3296        }
3297
3298        // Visit each excerpt that intersects the edit.
3299        let mut did_expand_hunks = false;
3300        while let Some(excerpt) = excerpts.item() {
3301            // Recompute the expanded hunks in the portion of the excerpt that
3302            // intersects the edit.
3303            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3304                let buffer = &excerpt.buffer;
3305                let excerpt_start = *excerpts.start();
3306                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3307                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3308                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3309                let edit_buffer_start =
3310                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3311                let edit_buffer_end =
3312                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3313                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3314                let edit_anchor_range =
3315                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3316
3317                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3318                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3319                        continue;
3320                    }
3321
3322                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3323                    if hunk_buffer_range.start < excerpt_buffer_start {
3324                        log::trace!("skipping hunk that starts before excerpt");
3325                        continue;
3326                    }
3327
3328                    let hunk_info = DiffTransformHunkInfo {
3329                        excerpt_id: excerpt.id,
3330                        hunk_start_anchor: hunk.buffer_range.start,
3331                        hunk_secondary_status: hunk.secondary_status,
3332                    };
3333
3334                    let hunk_excerpt_start = excerpt_start
3335                        + ExcerptOffset::new(
3336                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3337                        );
3338                    let hunk_excerpt_end = excerpt_end.min(
3339                        excerpt_start
3340                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3341                    );
3342
3343                    self.push_buffer_content_transform(
3344                        snapshot,
3345                        new_diff_transforms,
3346                        hunk_excerpt_start,
3347                        *end_of_current_insert,
3348                    );
3349
3350                    // For every existing hunk, determine if it was previously expanded
3351                    // and if it should currently be expanded.
3352                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3353                    let should_expand_hunk = match &change_kind {
3354                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3355                            was_previously_expanded || all_diff_hunks_expanded
3356                        }
3357                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3358                            let intersects = hunk_buffer_range.is_empty()
3359                                || hunk_buffer_range.end > edit_buffer_start;
3360                            if *expand {
3361                                intersects || was_previously_expanded || all_diff_hunks_expanded
3362                            } else {
3363                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3364                            }
3365                        }
3366                        _ => was_previously_expanded || all_diff_hunks_expanded,
3367                    };
3368
3369                    if should_expand_hunk {
3370                        did_expand_hunks = true;
3371                        log::trace!(
3372                            "expanding hunk {:?}, excerpt:{:?}",
3373                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3374                            excerpt.id
3375                        );
3376
3377                        if !hunk.diff_base_byte_range.is_empty()
3378                            && hunk_buffer_range.start >= edit_buffer_start
3379                            && hunk_buffer_range.start <= excerpt_buffer_end
3380                        {
3381                            let base_text = diff.base_text();
3382                            let mut text_cursor =
3383                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3384                            let mut base_text_summary =
3385                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3386
3387                            let mut has_trailing_newline = false;
3388                            if base_text_summary.last_line_chars > 0 {
3389                                base_text_summary += TextSummary::newline();
3390                                has_trailing_newline = true;
3391                            }
3392
3393                            new_diff_transforms.push(
3394                                DiffTransform::DeletedHunk {
3395                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3396                                    summary: base_text_summary,
3397                                    buffer_id: excerpt.buffer_id,
3398                                    hunk_info,
3399                                    has_trailing_newline,
3400                                },
3401                                &(),
3402                            );
3403                        }
3404
3405                        if !hunk_buffer_range.is_empty() {
3406                            *end_of_current_insert =
3407                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3408                        }
3409                    }
3410                }
3411            }
3412
3413            if excerpts.end() <= edit.new.end {
3414                excerpts.next();
3415            } else {
3416                break;
3417            }
3418        }
3419
3420        did_expand_hunks || !old_expanded_hunks.is_empty()
3421    }
3422
3423    fn append_diff_transforms(
3424        &self,
3425        new_transforms: &mut SumTree<DiffTransform>,
3426        subtree: SumTree<DiffTransform>,
3427    ) {
3428        if let Some(DiffTransform::BufferContent {
3429            inserted_hunk_info,
3430            summary,
3431        }) = subtree.first()
3432            && self.extend_last_buffer_content_transform(
3433                new_transforms,
3434                *inserted_hunk_info,
3435                *summary,
3436            )
3437        {
3438            let mut cursor = subtree.cursor::<()>(&());
3439            cursor.next();
3440            cursor.next();
3441            new_transforms.append(cursor.suffix(), &());
3442            return;
3443        }
3444        new_transforms.append(subtree, &());
3445    }
3446
3447    fn push_diff_transform(
3448        &self,
3449        new_transforms: &mut SumTree<DiffTransform>,
3450        transform: DiffTransform,
3451    ) {
3452        if let DiffTransform::BufferContent {
3453            inserted_hunk_info: inserted_hunk_anchor,
3454            summary,
3455        } = transform
3456            && self.extend_last_buffer_content_transform(
3457                new_transforms,
3458                inserted_hunk_anchor,
3459                summary,
3460            )
3461        {
3462            return;
3463        }
3464        new_transforms.push(transform, &());
3465    }
3466
3467    fn push_buffer_content_transform(
3468        &self,
3469        old_snapshot: &MultiBufferSnapshot,
3470        new_transforms: &mut SumTree<DiffTransform>,
3471        end_offset: ExcerptOffset,
3472        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3473    ) {
3474        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3475            (end_offset.min(insertion_end_offset), Some(hunk_info))
3476        });
3477        let unchanged_region = [(end_offset, None)];
3478
3479        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3480        {
3481            let start_offset = new_transforms.summary().excerpt_len();
3482            if end_offset <= start_offset {
3483                continue;
3484            }
3485            let summary_to_add = old_snapshot
3486                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3487
3488            if !self.extend_last_buffer_content_transform(
3489                new_transforms,
3490                inserted_hunk_info,
3491                summary_to_add,
3492            ) {
3493                new_transforms.push(
3494                    DiffTransform::BufferContent {
3495                        summary: summary_to_add,
3496                        inserted_hunk_info,
3497                    },
3498                    &(),
3499                )
3500            }
3501        }
3502    }
3503
3504    fn extend_last_buffer_content_transform(
3505        &self,
3506        new_transforms: &mut SumTree<DiffTransform>,
3507        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3508        summary_to_add: TextSummary,
3509    ) -> bool {
3510        let mut did_extend = false;
3511        new_transforms.update_last(
3512            |last_transform| {
3513                if let DiffTransform::BufferContent {
3514                    summary,
3515                    inserted_hunk_info: inserted_hunk_anchor,
3516                } = last_transform
3517                    && *inserted_hunk_anchor == new_inserted_hunk_info
3518                {
3519                    *summary += summary_to_add;
3520                    did_extend = true;
3521                }
3522            },
3523            &(),
3524        );
3525        did_extend
3526    }
3527}
3528
3529fn build_excerpt_ranges(
3530    ranges: impl IntoIterator<Item = Range<Point>>,
3531    context_line_count: u32,
3532    buffer_snapshot: &BufferSnapshot,
3533) -> Vec<ExcerptRange<Point>> {
3534    ranges
3535        .into_iter()
3536        .map(|range| {
3537            let start_row = range.start.row.saturating_sub(context_line_count);
3538            let start = Point::new(start_row, 0);
3539            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3540            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3541            ExcerptRange {
3542                context: start..end,
3543                primary: range,
3544            }
3545        })
3546        .collect()
3547}
3548
3549#[cfg(any(test, feature = "test-support"))]
3550impl MultiBuffer {
3551    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3552        let buffer = cx.new(|cx| Buffer::local(text, cx));
3553        cx.new(|cx| Self::singleton(buffer, cx))
3554    }
3555
3556    pub fn build_multi<const COUNT: usize>(
3557        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3558        cx: &mut gpui::App,
3559    ) -> Entity<Self> {
3560        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3561        for (text, ranges) in excerpts {
3562            let buffer = cx.new(|cx| Buffer::local(text, cx));
3563            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3564            multi.update(cx, |multi, cx| {
3565                multi.push_excerpts(buffer, excerpt_ranges, cx)
3566            });
3567        }
3568
3569        multi
3570    }
3571
3572    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3573        cx.new(|cx| Self::singleton(buffer, cx))
3574    }
3575
3576    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3577        cx.new(|cx| {
3578            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3579            let mutation_count = rng.gen_range(1..=5);
3580            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3581            multibuffer
3582        })
3583    }
3584
3585    pub fn randomly_edit(
3586        &mut self,
3587        rng: &mut impl rand::Rng,
3588        edit_count: usize,
3589        cx: &mut Context<Self>,
3590    ) {
3591        use util::RandomCharIter;
3592
3593        let snapshot = self.read(cx);
3594        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3595        let mut last_end = None;
3596        for _ in 0..edit_count {
3597            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3598                break;
3599            }
3600
3601            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3602            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
3603            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
3604            last_end = Some(end);
3605
3606            let mut range = start..end;
3607            if rng.gen_bool(0.2) {
3608                mem::swap(&mut range.start, &mut range.end);
3609            }
3610
3611            let new_text_len = rng.gen_range(0..10);
3612            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3613
3614            edits.push((range, new_text.into()));
3615        }
3616        log::info!("mutating multi-buffer with {:?}", edits);
3617        drop(snapshot);
3618
3619        self.edit(edits, None, cx);
3620    }
3621
3622    pub fn randomly_edit_excerpts(
3623        &mut self,
3624        rng: &mut impl rand::Rng,
3625        mutation_count: usize,
3626        cx: &mut Context<Self>,
3627    ) {
3628        use rand::prelude::*;
3629        use std::env;
3630        use util::RandomCharIter;
3631
3632        let max_excerpts = env::var("MAX_EXCERPTS")
3633            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3634            .unwrap_or(5);
3635
3636        let mut buffers = Vec::new();
3637        for _ in 0..mutation_count {
3638            if rng.gen_bool(0.05) {
3639                log::info!("Clearing multi-buffer");
3640                self.clear(cx);
3641                continue;
3642            } else if rng.gen_bool(0.1) && !self.excerpt_ids().is_empty() {
3643                let ids = self.excerpt_ids();
3644                let mut excerpts = HashSet::default();
3645                for _ in 0..rng.gen_range(0..ids.len()) {
3646                    excerpts.extend(ids.choose(rng).copied());
3647                }
3648
3649                let line_count = rng.gen_range(0..5);
3650
3651                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3652
3653                self.expand_excerpts(
3654                    excerpts.iter().cloned(),
3655                    line_count,
3656                    ExpandExcerptDirection::UpAndDown,
3657                    cx,
3658                );
3659                continue;
3660            }
3661
3662            let excerpt_ids = self.excerpt_ids();
3663            if excerpt_ids.is_empty() || (rng.r#gen() && excerpt_ids.len() < max_excerpts) {
3664                let buffer_handle = if rng.r#gen() || self.buffers.borrow().is_empty() {
3665                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3666                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3667                    let buffer = buffers.last().unwrap().read(cx);
3668                    log::info!(
3669                        "Creating new buffer {} with text: {:?}",
3670                        buffer.remote_id(),
3671                        buffer.text()
3672                    );
3673                    buffers.last().unwrap().clone()
3674                } else {
3675                    self.buffers
3676                        .borrow()
3677                        .values()
3678                        .choose(rng)
3679                        .unwrap()
3680                        .buffer
3681                        .clone()
3682                };
3683
3684                let buffer = buffer_handle.read(cx);
3685                let buffer_text = buffer.text();
3686                let ranges = (0..rng.gen_range(0..5))
3687                    .map(|_| {
3688                        let end_ix =
3689                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3690                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3691                        ExcerptRange::new(start_ix..end_ix)
3692                    })
3693                    .collect::<Vec<_>>();
3694                log::info!(
3695                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3696                    buffer_handle.read(cx).remote_id(),
3697                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3698                    ranges
3699                        .iter()
3700                        .map(|r| &buffer_text[r.context.clone()])
3701                        .collect::<Vec<_>>()
3702                );
3703
3704                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3705                log::info!("Inserted with ids: {:?}", excerpt_id);
3706            } else {
3707                let remove_count = rng.gen_range(1..=excerpt_ids.len());
3708                let mut excerpts_to_remove = excerpt_ids
3709                    .choose_multiple(rng, remove_count)
3710                    .cloned()
3711                    .collect::<Vec<_>>();
3712                let snapshot = self.snapshot.borrow();
3713                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3714                drop(snapshot);
3715                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3716                self.remove_excerpts(excerpts_to_remove, cx);
3717            }
3718        }
3719    }
3720
3721    pub fn randomly_mutate(
3722        &mut self,
3723        rng: &mut impl rand::Rng,
3724        mutation_count: usize,
3725        cx: &mut Context<Self>,
3726    ) {
3727        use rand::prelude::*;
3728
3729        if rng.gen_bool(0.7) || self.singleton {
3730            let buffer = self
3731                .buffers
3732                .borrow()
3733                .values()
3734                .choose(rng)
3735                .map(|state| state.buffer.clone());
3736
3737            if let Some(buffer) = buffer {
3738                buffer.update(cx, |buffer, cx| {
3739                    if rng.r#gen() {
3740                        buffer.randomly_edit(rng, mutation_count, cx);
3741                    } else {
3742                        buffer.randomly_undo_redo(rng, cx);
3743                    }
3744                });
3745            } else {
3746                self.randomly_edit(rng, mutation_count, cx);
3747            }
3748        } else {
3749            self.randomly_edit_excerpts(rng, mutation_count, cx);
3750        }
3751
3752        self.check_invariants(cx);
3753    }
3754
3755    fn check_invariants(&self, cx: &App) {
3756        self.read(cx).check_invariants();
3757    }
3758}
3759
3760impl EventEmitter<Event> for MultiBuffer {}
3761
3762impl MultiBufferSnapshot {
3763    pub fn text(&self) -> String {
3764        self.chunks(0..self.len(), false)
3765            .map(|chunk| chunk.text)
3766            .collect()
3767    }
3768
3769    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3770        self.reversed_chunks_in_range(0..position.to_offset(self))
3771            .flat_map(|c| c.chars().rev())
3772    }
3773
3774    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3775        let mut cursor = self.cursor::<usize>();
3776        cursor.seek(&range.end);
3777        let current_chunks = cursor.region().as_ref().map(|region| {
3778            let start_overshoot = range.start.saturating_sub(region.range.start);
3779            let end_overshoot = range.end - region.range.start;
3780            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3781            let start = region.buffer_range.start + start_overshoot;
3782            region.buffer.reversed_chunks_in_range(start..end)
3783        });
3784        ReversedMultiBufferChunks {
3785            cursor,
3786            current_chunks,
3787            start: range.start,
3788            offset: range.end,
3789        }
3790    }
3791
3792    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3793        let offset = position.to_offset(self);
3794        self.text_for_range(offset..self.len())
3795            .flat_map(|chunk| chunk.chars())
3796    }
3797
3798    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3799        self.chunks(range, false).map(|chunk| chunk.text)
3800    }
3801
3802    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3803        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3804            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3805    }
3806
3807    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3808    where
3809        T: ToOffset,
3810    {
3811        let position = position.to_offset(self);
3812        position == self.clip_offset(position, Bias::Left)
3813            && self
3814                .bytes_in_range(position..self.len())
3815                .flatten()
3816                .copied()
3817                .take(needle.len())
3818                .eq(needle.bytes())
3819    }
3820
3821    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3822        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3823    }
3824
3825    pub fn diff_hunks_in_range<T: ToPoint>(
3826        &self,
3827        range: Range<T>,
3828    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3829        let query_range = range.start.to_point(self)..range.end.to_point(self);
3830        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3831            let diff = self.diffs.get(&buffer.remote_id())?;
3832            let buffer_start = buffer.anchor_before(buffer_range.start);
3833            let buffer_end = buffer.anchor_after(buffer_range.end);
3834            Some(
3835                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3836                    .filter_map(|hunk| {
3837                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3838                            return None;
3839                        }
3840                        Some((hunk.range.clone(), hunk))
3841                    }),
3842            )
3843        })
3844        .filter_map(move |(range, hunk, excerpt)| {
3845            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3846            {
3847                return None;
3848            }
3849            let end_row = if range.end.column == 0 {
3850                range.end.row
3851            } else {
3852                range.end.row + 1
3853            };
3854            Some(MultiBufferDiffHunk {
3855                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3856                buffer_id: excerpt.buffer_id,
3857                excerpt_id: excerpt.id,
3858                buffer_range: hunk.buffer_range.clone(),
3859                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3860                secondary_status: hunk.secondary_status,
3861            })
3862        })
3863    }
3864
3865    pub fn excerpt_ids_for_range<T: ToOffset>(
3866        &self,
3867        range: Range<T>,
3868    ) -> impl Iterator<Item = ExcerptId> + '_ {
3869        let range = range.start.to_offset(self)..range.end.to_offset(self);
3870        let mut cursor = self.cursor::<usize>();
3871        cursor.seek(&range.start);
3872        std::iter::from_fn(move || {
3873            let region = cursor.region()?;
3874            if region.range.start >= range.end {
3875                return None;
3876            }
3877            cursor.next_excerpt();
3878            Some(region.excerpt.id)
3879        })
3880    }
3881
3882    pub fn buffer_ids_for_range<T: ToOffset>(
3883        &self,
3884        range: Range<T>,
3885    ) -> impl Iterator<Item = BufferId> + '_ {
3886        let range = range.start.to_offset(self)..range.end.to_offset(self);
3887        let mut cursor = self.cursor::<usize>();
3888        cursor.seek(&range.start);
3889        std::iter::from_fn(move || {
3890            let region = cursor.region()?;
3891            if region.range.start > range.end
3892                || region.range.start == range.end && region.range.start > range.start
3893            {
3894                return None;
3895            }
3896            cursor.next_excerpt();
3897            Some(region.excerpt.buffer_id)
3898        })
3899    }
3900
3901    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3902        &self,
3903        ranges: impl Iterator<Item = Range<T>>,
3904    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3905        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3906    }
3907
3908    pub fn range_to_buffer_ranges<T: ToOffset>(
3909        &self,
3910        range: Range<T>,
3911    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3912        let start = range.start.to_offset(self);
3913        let end = range.end.to_offset(self);
3914
3915        let mut cursor = self.cursor::<usize>();
3916        cursor.seek(&start);
3917
3918        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3919        while let Some(region) = cursor.region() {
3920            if region.range.start > end {
3921                break;
3922            }
3923            if region.is_main_buffer {
3924                let start_overshoot = start.saturating_sub(region.range.start);
3925                let end_overshoot = end.saturating_sub(region.range.start);
3926                let start = region
3927                    .buffer_range
3928                    .end
3929                    .min(region.buffer_range.start + start_overshoot);
3930                let end = region
3931                    .buffer_range
3932                    .end
3933                    .min(region.buffer_range.start + end_overshoot);
3934                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3935                    *excerpt_id == region.excerpt.id && prev_range.end == start
3936                }) {
3937                    prev.1.end = end;
3938                } else {
3939                    result.push((region.buffer, start..end, region.excerpt.id));
3940                }
3941            }
3942            cursor.next();
3943        }
3944        result
3945    }
3946
3947    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3948        &self,
3949        range: Range<T>,
3950    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3951        let start = range.start.to_offset(self);
3952        let end = range.end.to_offset(self);
3953
3954        let mut cursor = self.cursor::<usize>();
3955        cursor.seek(&start);
3956
3957        std::iter::from_fn(move || {
3958            let region = cursor.region()?;
3959            if region.range.start > end {
3960                return None;
3961            }
3962            let start_overshoot = start.saturating_sub(region.range.start);
3963            let end_overshoot = end.saturating_sub(region.range.start);
3964            let start = region
3965                .buffer_range
3966                .end
3967                .min(region.buffer_range.start + start_overshoot);
3968            let end = region
3969                .buffer_range
3970                .end
3971                .min(region.buffer_range.start + end_overshoot);
3972
3973            let region_excerpt_id = region.excerpt.id;
3974            let deleted_hunk_anchor = if region.is_main_buffer {
3975                None
3976            } else {
3977                Some(self.anchor_before(region.range.start))
3978            };
3979            let result = (
3980                region.buffer,
3981                start..end,
3982                region_excerpt_id,
3983                deleted_hunk_anchor,
3984            );
3985            cursor.next();
3986            Some(result)
3987        })
3988    }
3989
3990    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3991    /// coordinates.
3992    ///
3993    /// The given callback will be called for every excerpt intersecting the given range. It will
3994    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3995    /// The callback should return an iterator of metadata items from that buffer, each paired
3996    /// with a buffer range.
3997    ///
3998    /// The returned iterator yields each of these metadata items, paired with its range in
3999    /// multi-buffer coordinates.
4000    fn lift_buffer_metadata<'a, D, M, I>(
4001        &'a self,
4002        query_range: Range<D>,
4003        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
4004    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
4005    where
4006        I: Iterator<Item = (Range<D>, M)> + 'a,
4007        D: TextDimension + Ord + Sub<D, Output = D>,
4008    {
4009        let max_position = D::from_text_summary(&self.text_summary());
4010        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4011        let mut cursor = self.cursor::<D>();
4012
4013        // Find the excerpt and buffer offset where the given range ends.
4014        cursor.seek(&query_range.end);
4015        let mut range_end = None;
4016        while let Some(region) = cursor.region() {
4017            if region.is_main_buffer {
4018                let mut buffer_end = region.buffer_range.start;
4019                let overshoot = if query_range.end > region.range.start {
4020                    query_range.end - region.range.start
4021                } else {
4022                    D::default()
4023                };
4024                buffer_end.add_assign(&overshoot);
4025                range_end = Some((region.excerpt.id, buffer_end));
4026                break;
4027            }
4028            cursor.next();
4029        }
4030
4031        cursor.seek(&query_range.start);
4032
4033        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4034            && region.range.start > D::zero(&())
4035        {
4036            cursor.prev()
4037        }
4038
4039        iter::from_fn(move || {
4040            loop {
4041                let excerpt = cursor.excerpt()?;
4042
4043                // If we have already retrieved metadata for this excerpt, continue to use it.
4044                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4045                    .as_mut()
4046                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4047                {
4048                    Some(metadata)
4049                }
4050                // Otherwise, compute the intersection of the input range with the excerpt's range,
4051                // and retrieve the metadata for the resulting range.
4052                else {
4053                    let region = cursor.region()?;
4054                    let mut buffer_start;
4055                    if region.is_main_buffer {
4056                        buffer_start = region.buffer_range.start;
4057                        if query_range.start > region.range.start {
4058                            let overshoot = query_range.start - region.range.start;
4059                            buffer_start.add_assign(&overshoot);
4060                        }
4061                        buffer_start = buffer_start.min(region.buffer_range.end);
4062                    } else {
4063                        buffer_start = cursor.main_buffer_position()?;
4064                    };
4065                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4066                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4067                        && excerpt.id == end_excerpt_id
4068                    {
4069                        buffer_end = buffer_end.min(end_buffer_offset);
4070                    }
4071
4072                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4073                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4074                    })
4075                };
4076
4077                // Visit each metadata item.
4078                if let Some((metadata_buffer_range, metadata)) =
4079                    metadata_iter.and_then(Iterator::next)
4080                {
4081                    // Find the multibuffer regions that contain the start and end of
4082                    // the metadata item's range.
4083                    if metadata_buffer_range.start > D::default() {
4084                        while let Some(region) = cursor.region() {
4085                            if region.is_main_buffer
4086                                && (region.buffer_range.end >= metadata_buffer_range.start
4087                                    || cursor.is_at_end_of_excerpt())
4088                            {
4089                                break;
4090                            }
4091                            cursor.next();
4092                        }
4093                    }
4094                    let start_region = cursor.region()?;
4095                    while let Some(region) = cursor.region() {
4096                        if region.is_main_buffer
4097                            && (region.buffer_range.end > metadata_buffer_range.end
4098                                || cursor.is_at_end_of_excerpt())
4099                        {
4100                            break;
4101                        }
4102                        cursor.next();
4103                    }
4104                    let end_region = cursor.region();
4105
4106                    // Convert the metadata item's range into multibuffer coordinates.
4107                    let mut start_position = start_region.range.start;
4108                    let region_buffer_start = start_region.buffer_range.start;
4109                    if start_region.is_main_buffer
4110                        && metadata_buffer_range.start > region_buffer_start
4111                    {
4112                        start_position
4113                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4114                        start_position = start_position.min(start_region.range.end);
4115                    }
4116
4117                    let mut end_position = max_position;
4118                    if let Some(end_region) = &end_region {
4119                        end_position = end_region.range.start;
4120                        debug_assert!(end_region.is_main_buffer);
4121                        let region_buffer_start = end_region.buffer_range.start;
4122                        if metadata_buffer_range.end > region_buffer_start {
4123                            end_position
4124                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4125                        }
4126                        end_position = end_position.min(end_region.range.end);
4127                    }
4128
4129                    if start_position <= query_range.end && end_position >= query_range.start {
4130                        return Some((start_position..end_position, metadata, excerpt));
4131                    }
4132                }
4133                // When there are no more metadata items for this excerpt, move to the next excerpt.
4134                else {
4135                    current_excerpt_metadata.take();
4136                    if let Some((end_excerpt_id, _)) = range_end
4137                        && excerpt.id == end_excerpt_id
4138                    {
4139                        return None;
4140                    }
4141                    cursor.next_excerpt();
4142                }
4143            }
4144        })
4145    }
4146
4147    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4148        let offset = position.to_offset(self);
4149
4150        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4151        cursor.seek(&DimensionPair {
4152            key: offset,
4153            value: None,
4154        });
4155        cursor.seek_to_start_of_current_excerpt();
4156        let excerpt = cursor.excerpt()?;
4157
4158        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4159        let current_position = self
4160            .anchor_before(offset)
4161            .text_anchor
4162            .to_offset(&excerpt.buffer);
4163        let excerpt_end = excerpt
4164            .buffer
4165            .anchor_before(excerpt_end.min(current_position));
4166
4167        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4168            for hunk in diff.hunks_intersecting_range_rev(
4169                excerpt.range.context.start..excerpt_end,
4170                &excerpt.buffer,
4171            ) {
4172                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4173                if hunk_end >= current_position {
4174                    continue;
4175                }
4176                let start =
4177                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4178                        .to_point(self);
4179                return Some(MultiBufferRow(start.row));
4180            }
4181        }
4182
4183        loop {
4184            cursor.prev_excerpt();
4185            let excerpt = cursor.excerpt()?;
4186
4187            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4188                continue;
4189            };
4190            let mut hunks =
4191                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4192            let Some(hunk) = hunks.next() else {
4193                continue;
4194            };
4195            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4196                .to_point(self);
4197            return Some(MultiBufferRow(start.row));
4198        }
4199    }
4200
4201    pub fn has_diff_hunks(&self) -> bool {
4202        self.diffs.values().any(|diff| !diff.is_empty())
4203    }
4204
4205    pub fn is_inside_word<T: ToOffset>(&self, position: T, for_completion: bool) -> bool {
4206        let position = position.to_offset(self);
4207        let classifier = self
4208            .char_classifier_at(position)
4209            .for_completion(for_completion);
4210        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4211        let prev_char_kind = self
4212            .reversed_chars_at(position)
4213            .next()
4214            .map(|c| classifier.kind(c));
4215        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4216    }
4217
4218    pub fn surrounding_word<T: ToOffset>(
4219        &self,
4220        start: T,
4221        for_completion: bool,
4222    ) -> (Range<usize>, Option<CharKind>) {
4223        let mut start = start.to_offset(self);
4224        let mut end = start;
4225        let mut next_chars = self.chars_at(start).peekable();
4226        let mut prev_chars = self.reversed_chars_at(start).peekable();
4227
4228        let classifier = self
4229            .char_classifier_at(start)
4230            .for_completion(for_completion);
4231
4232        let word_kind = cmp::max(
4233            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4234            next_chars.peek().copied().map(|c| classifier.kind(c)),
4235        );
4236
4237        for ch in prev_chars {
4238            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4239                start -= ch.len_utf8();
4240            } else {
4241                break;
4242            }
4243        }
4244
4245        for ch in next_chars {
4246            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4247                end += ch.len_utf8();
4248            } else {
4249                break;
4250            }
4251        }
4252
4253        (start..end, word_kind)
4254    }
4255
4256    pub fn char_kind_before<T: ToOffset>(
4257        &self,
4258        start: T,
4259        for_completion: bool,
4260    ) -> Option<CharKind> {
4261        let start = start.to_offset(self);
4262        let classifier = self
4263            .char_classifier_at(start)
4264            .for_completion(for_completion);
4265        self.reversed_chars_at(start)
4266            .next()
4267            .map(|ch| classifier.kind(ch))
4268    }
4269
4270    pub fn is_singleton(&self) -> bool {
4271        self.singleton
4272    }
4273
4274    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4275        if self.singleton {
4276            self.excerpts
4277                .iter()
4278                .next()
4279                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4280        } else {
4281            None
4282        }
4283    }
4284
4285    pub fn len(&self) -> usize {
4286        self.diff_transforms.summary().output.len
4287    }
4288
4289    pub fn is_empty(&self) -> bool {
4290        self.excerpts.summary().text.len == 0
4291    }
4292
4293    pub fn widest_line_number(&self) -> u32 {
4294        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4295        self.excerpts.summary().widest_line_number + 1
4296    }
4297
4298    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4299        let range = range.start.to_offset(self)..range.end.to_offset(self);
4300        let mut excerpts = self.cursor::<usize>();
4301        excerpts.seek(&range.start);
4302
4303        let mut chunk;
4304        let mut has_trailing_newline;
4305        let excerpt_bytes;
4306        if let Some(region) = excerpts.region() {
4307            let mut bytes = region.buffer.bytes_in_range(
4308                region.buffer_range.start + range.start - region.range.start
4309                    ..(region.buffer_range.start + range.end - region.range.start)
4310                        .min(region.buffer_range.end),
4311            );
4312            chunk = bytes.next().unwrap_or(&[][..]);
4313            excerpt_bytes = Some(bytes);
4314            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4315            if chunk.is_empty() && has_trailing_newline {
4316                chunk = b"\n";
4317                has_trailing_newline = false;
4318            }
4319        } else {
4320            chunk = &[][..];
4321            excerpt_bytes = None;
4322            has_trailing_newline = false;
4323        };
4324
4325        MultiBufferBytes {
4326            range,
4327            cursor: excerpts,
4328            excerpt_bytes,
4329            has_trailing_newline,
4330            chunk,
4331        }
4332    }
4333
4334    pub fn reversed_bytes_in_range<T: ToOffset>(
4335        &self,
4336        range: Range<T>,
4337    ) -> ReversedMultiBufferBytes<'_> {
4338        let range = range.start.to_offset(self)..range.end.to_offset(self);
4339        let mut chunks = self.reversed_chunks_in_range(range.clone());
4340        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4341        ReversedMultiBufferBytes {
4342            range,
4343            chunks,
4344            chunk,
4345        }
4346    }
4347
4348    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4349        let mut cursor = self.cursor::<Point>();
4350        cursor.seek(&Point::new(start_row.0, 0));
4351        let mut result = MultiBufferRows {
4352            point: Point::new(0, 0),
4353            is_empty: self.excerpts.is_empty(),
4354            is_singleton: self.is_singleton(),
4355            cursor,
4356        };
4357        result.seek(start_row);
4358        result
4359    }
4360
4361    pub fn chunks<T: ToOffset>(
4362        &self,
4363        range: Range<T>,
4364        language_aware: bool,
4365    ) -> MultiBufferChunks<'_> {
4366        let mut chunks = MultiBufferChunks {
4367            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4368            range: 0..0,
4369            excerpts: self.excerpts.cursor(&()),
4370            diff_transforms: self.diff_transforms.cursor(&()),
4371            diffs: &self.diffs,
4372            diff_base_chunks: None,
4373            excerpt_chunks: None,
4374            buffer_chunk: None,
4375            language_aware,
4376        };
4377        let range = range.start.to_offset(self)..range.end.to_offset(self);
4378        chunks.seek(range);
4379        chunks
4380    }
4381
4382    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4383        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4384    }
4385
4386    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4387        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4388    }
4389
4390    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4391        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4392    }
4393
4394    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4395        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4396            buffer.clip_point_utf16(Unclipped(point), bias)
4397        })
4398    }
4399
4400    pub fn offset_to_point(&self, offset: usize) -> Point {
4401        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4402    }
4403
4404    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4405        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4406    }
4407
4408    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4409        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4410    }
4411
4412    pub fn point_to_offset(&self, point: Point) -> usize {
4413        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4414    }
4415
4416    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4417        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4418    }
4419
4420    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4421        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4422    }
4423
4424    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4425        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4426    }
4427
4428    fn clip_dimension<D>(
4429        &self,
4430        position: D,
4431        bias: Bias,
4432        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4433    ) -> D
4434    where
4435        D: TextDimension + Ord + Sub<D, Output = D>,
4436    {
4437        let mut cursor = self.cursor();
4438        cursor.seek(&position);
4439        if let Some(region) = cursor.region() {
4440            if position >= region.range.end {
4441                return region.range.end;
4442            }
4443            let overshoot = position - region.range.start;
4444            let mut buffer_position = region.buffer_range.start;
4445            buffer_position.add_assign(&overshoot);
4446            let clipped_buffer_position =
4447                clip_buffer_position(region.buffer, buffer_position, bias);
4448            let mut position = region.range.start;
4449            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4450            position
4451        } else {
4452            D::from_text_summary(&self.text_summary())
4453        }
4454    }
4455
4456    fn convert_dimension<D1, D2>(
4457        &self,
4458        key: D1,
4459        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4460    ) -> D2
4461    where
4462        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4463        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4464    {
4465        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4466        cursor.seek(&DimensionPair { key, value: None });
4467        if let Some(region) = cursor.region() {
4468            if key >= region.range.end.key {
4469                return region.range.end.value.unwrap();
4470            }
4471            let start_key = region.range.start.key;
4472            let start_value = region.range.start.value.unwrap();
4473            let buffer_start_key = region.buffer_range.start.key;
4474            let buffer_start_value = region.buffer_range.start.value.unwrap();
4475            let mut buffer_key = buffer_start_key;
4476            buffer_key.add_assign(&(key - start_key));
4477            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4478            let mut result = start_value;
4479            result.add_assign(&(buffer_value - buffer_start_value));
4480            result
4481        } else {
4482            D2::from_text_summary(&self.text_summary())
4483        }
4484    }
4485
4486    pub fn point_to_buffer_offset<T: ToOffset>(
4487        &self,
4488        point: T,
4489    ) -> Option<(&BufferSnapshot, usize)> {
4490        let offset = point.to_offset(self);
4491        let mut cursor = self.cursor::<usize>();
4492        cursor.seek(&offset);
4493        let region = cursor.region()?;
4494        let overshoot = offset - region.range.start;
4495        let buffer_offset = region.buffer_range.start + overshoot;
4496        if buffer_offset == region.buffer.len() + 1
4497            && region.has_trailing_newline
4498            && !region.is_main_buffer
4499        {
4500            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4501        } else if buffer_offset > region.buffer.len() {
4502            return None;
4503        }
4504        Some((region.buffer, buffer_offset))
4505    }
4506
4507    pub fn point_to_buffer_point(
4508        &self,
4509        point: Point,
4510    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4511        let mut cursor = self.cursor::<Point>();
4512        cursor.seek(&point);
4513        let region = cursor.region()?;
4514        let overshoot = point - region.range.start;
4515        let buffer_point = region.buffer_range.start + overshoot;
4516        let excerpt = cursor.excerpt()?;
4517        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4518            && region.has_trailing_newline
4519            && !region.is_main_buffer
4520        {
4521            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4522        } else if buffer_point > region.buffer.max_point() {
4523            return None;
4524        }
4525        Some((region.buffer, buffer_point, excerpt.id))
4526    }
4527
4528    pub fn suggested_indents(
4529        &self,
4530        rows: impl IntoIterator<Item = u32>,
4531        cx: &App,
4532    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4533        let mut result = BTreeMap::new();
4534
4535        let mut rows_for_excerpt = Vec::new();
4536        let mut cursor = self.cursor::<Point>();
4537        let mut rows = rows.into_iter().peekable();
4538        let mut prev_row = u32::MAX;
4539        let mut prev_language_indent_size = IndentSize::default();
4540
4541        while let Some(row) = rows.next() {
4542            cursor.seek(&Point::new(row, 0));
4543            let Some(region) = cursor.region() else {
4544                continue;
4545            };
4546
4547            // Retrieve the language and indent size once for each disjoint region being indented.
4548            let single_indent_size = if row.saturating_sub(1) == prev_row {
4549                prev_language_indent_size
4550            } else {
4551                region
4552                    .buffer
4553                    .language_indent_size_at(Point::new(row, 0), cx)
4554            };
4555            prev_language_indent_size = single_indent_size;
4556            prev_row = row;
4557
4558            let start_buffer_row = region.buffer_range.start.row;
4559            let start_multibuffer_row = region.range.start.row;
4560            let end_multibuffer_row = region.range.end.row;
4561
4562            rows_for_excerpt.push(row);
4563            while let Some(next_row) = rows.peek().copied() {
4564                if end_multibuffer_row > next_row {
4565                    rows_for_excerpt.push(next_row);
4566                    rows.next();
4567                } else {
4568                    break;
4569                }
4570            }
4571
4572            let buffer_rows = rows_for_excerpt
4573                .drain(..)
4574                .map(|row| start_buffer_row + row - start_multibuffer_row);
4575            let buffer_indents = region
4576                .buffer
4577                .suggested_indents(buffer_rows, single_indent_size);
4578            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4579                (
4580                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4581                    indent,
4582                )
4583            });
4584            result.extend(multibuffer_indents);
4585        }
4586
4587        result
4588    }
4589
4590    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4591        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4592            let mut size = buffer.indent_size_for_line(range.start.row);
4593            size.len = size
4594                .len
4595                .min(range.end.column)
4596                .saturating_sub(range.start.column);
4597            size
4598        } else {
4599            IndentSize::spaces(0)
4600        }
4601    }
4602
4603    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4604        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4605            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4606        } else {
4607            LineIndent::spaces(0)
4608        }
4609    }
4610
4611    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4612        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4613
4614        if self.language_settings(cx).extend_comment_on_newline
4615            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4616        {
4617            let delimiters = language_scope.line_comment_prefixes();
4618            for delimiter in delimiters {
4619                if *self
4620                    .chars_at(Point::new(row.0, indent.len() as u32))
4621                    .take(delimiter.chars().count())
4622                    .collect::<String>()
4623                    .as_str()
4624                    == **delimiter
4625                {
4626                    indent.push_str(delimiter);
4627                    break;
4628                }
4629            }
4630        }
4631
4632        indent
4633    }
4634
4635    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4636    where
4637        T: ToOffset,
4638    {
4639        for char in self.reversed_chars_at(position) {
4640            if !char.is_whitespace() {
4641                return false;
4642            }
4643            if char == '\n' {
4644                return true;
4645            }
4646        }
4647        true
4648    }
4649
4650    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4651        while row.0 > 0 {
4652            row.0 -= 1;
4653            if !self.is_line_blank(row) {
4654                return Some(row);
4655            }
4656        }
4657        None
4658    }
4659
4660    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4661        if let Some((_, range)) = self.buffer_line_for_row(row) {
4662            range.end.column - range.start.column
4663        } else {
4664            0
4665        }
4666    }
4667
4668    pub fn buffer_line_for_row(
4669        &self,
4670        row: MultiBufferRow,
4671    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4672        let mut cursor = self.cursor::<Point>();
4673        let point = Point::new(row.0, 0);
4674        cursor.seek(&point);
4675        let region = cursor.region()?;
4676        let overshoot = point.min(region.range.end) - region.range.start;
4677        let buffer_point = region.buffer_range.start + overshoot;
4678        if buffer_point.row > region.buffer_range.end.row {
4679            return None;
4680        }
4681        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4682        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4683            .min(region.buffer_range.end);
4684        Some((region.buffer, line_start..line_end))
4685    }
4686
4687    pub fn max_point(&self) -> Point {
4688        self.text_summary().lines
4689    }
4690
4691    pub fn max_row(&self) -> MultiBufferRow {
4692        MultiBufferRow(self.text_summary().lines.row)
4693    }
4694
4695    pub fn text_summary(&self) -> TextSummary {
4696        self.diff_transforms.summary().output
4697    }
4698
4699    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4700    where
4701        D: TextDimension,
4702        O: ToOffset,
4703    {
4704        let range = range.start.to_offset(self)..range.end.to_offset(self);
4705        let mut cursor = self
4706            .diff_transforms
4707            .cursor::<Dimensions<usize, ExcerptOffset>>(&());
4708        cursor.seek(&range.start, Bias::Right);
4709
4710        let Some(first_transform) = cursor.item() else {
4711            return D::from_text_summary(&TextSummary::default());
4712        };
4713
4714        let diff_transform_start = cursor.start().0;
4715        let diff_transform_end = cursor.end().0;
4716        let diff_start = range.start;
4717        let start_overshoot = diff_start - diff_transform_start;
4718        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4719
4720        let mut result = match first_transform {
4721            DiffTransform::BufferContent { .. } => {
4722                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4723                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4724                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4725            }
4726            DiffTransform::DeletedHunk {
4727                buffer_id,
4728                base_text_byte_range,
4729                has_trailing_newline,
4730                ..
4731            } => {
4732                let buffer_start = base_text_byte_range.start + start_overshoot;
4733                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4734                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4735                    panic!("{:?} is in non-existent deleted hunk", range.start)
4736                };
4737
4738                let include_trailing_newline =
4739                    *has_trailing_newline && range.end >= diff_transform_end;
4740                if include_trailing_newline {
4741                    buffer_end -= 1;
4742                }
4743
4744                let mut summary =
4745                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4746
4747                if include_trailing_newline {
4748                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4749                }
4750
4751                summary
4752            }
4753        };
4754        if range.end < diff_transform_end {
4755            return result;
4756        }
4757
4758        cursor.next();
4759        result.add_assign(&D::from_text_summary(
4760            &cursor.summary(&range.end, Bias::Right),
4761        ));
4762
4763        let Some(last_transform) = cursor.item() else {
4764            return result;
4765        };
4766
4767        let overshoot = range.end - cursor.start().0;
4768        let suffix = match last_transform {
4769            DiffTransform::BufferContent { .. } => {
4770                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4771                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4772            }
4773            DiffTransform::DeletedHunk {
4774                base_text_byte_range,
4775                buffer_id,
4776                has_trailing_newline,
4777                ..
4778            } => {
4779                let buffer_end = base_text_byte_range.start + overshoot;
4780                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4781                    panic!("{:?} is in non-existent deleted hunk", range.end)
4782                };
4783
4784                let mut suffix = base_text
4785                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4786                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4787                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4788                }
4789                suffix
4790            }
4791        };
4792
4793        result.add_assign(&suffix);
4794        result
4795    }
4796
4797    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4798    where
4799        D: TextDimension,
4800    {
4801        // let mut range = range.start..range.end;
4802        let mut summary = D::zero(&());
4803        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(&());
4804        cursor.seek(&range.start, Bias::Right);
4805        if let Some(excerpt) = cursor.item() {
4806            let mut end_before_newline = cursor.end();
4807            if excerpt.has_trailing_newline {
4808                end_before_newline -= ExcerptOffset::new(1);
4809            }
4810
4811            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4812            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4813            let end_in_excerpt =
4814                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4815            summary.add_assign(
4816                &excerpt
4817                    .buffer
4818                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4819            );
4820
4821            if range.end > end_before_newline {
4822                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4823            }
4824
4825            cursor.next();
4826        }
4827
4828        if range.end > *cursor.start() {
4829            summary.add_assign(
4830                &cursor
4831                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right)
4832                    .0,
4833            );
4834            if let Some(excerpt) = cursor.item() {
4835                range.end = cmp::max(*cursor.start(), range.end);
4836
4837                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4838                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4839                summary.add_assign(
4840                    &excerpt
4841                        .buffer
4842                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4843                );
4844            }
4845        }
4846
4847        summary
4848    }
4849
4850    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4851    where
4852        D: TextDimension + Ord + Sub<D, Output = D>,
4853    {
4854        self.summaries_for_anchors([anchor])[0]
4855    }
4856
4857    fn resolve_summary_for_anchor<D>(
4858        &self,
4859        anchor: &Anchor,
4860        excerpt_position: D,
4861        diff_transforms: &mut Cursor<
4862            DiffTransform,
4863            Dimensions<ExcerptDimension<D>, OutputDimension<D>>,
4864        >,
4865    ) -> D
4866    where
4867        D: TextDimension + Ord + Sub<D, Output = D>,
4868    {
4869        loop {
4870            let transform_end_position = diff_transforms.end().0.0;
4871            let at_transform_end =
4872                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4873            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4874                diff_transforms.next();
4875                continue;
4876            }
4877
4878            let mut position = diff_transforms.start().1.0;
4879            match diff_transforms.item() {
4880                Some(DiffTransform::DeletedHunk {
4881                    buffer_id,
4882                    base_text_byte_range,
4883                    ..
4884                }) => {
4885                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
4886                        && let Some(base_text) =
4887                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4888                        && base_text.can_resolve(diff_base_anchor)
4889                    {
4890                        let base_text_offset = diff_base_anchor.to_offset(base_text);
4891                        if base_text_offset >= base_text_byte_range.start
4892                            && base_text_offset <= base_text_byte_range.end
4893                        {
4894                            let position_in_hunk = base_text.text_summary_for_range::<D, _>(
4895                                base_text_byte_range.start..base_text_offset,
4896                            );
4897                            position.add_assign(&position_in_hunk);
4898                        } else if at_transform_end {
4899                            diff_transforms.next();
4900                            continue;
4901                        }
4902                    }
4903                }
4904                _ => {
4905                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4906                        diff_transforms.next();
4907                        continue;
4908                    }
4909                    let overshoot = excerpt_position - diff_transforms.start().0.0;
4910                    position.add_assign(&overshoot);
4911                }
4912            }
4913
4914            return position;
4915        }
4916    }
4917
4918    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4919        let mut cursor = self
4920            .excerpts
4921            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(&());
4922        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4923
4924        cursor.seek(&Some(locator), Bias::Left);
4925        if cursor.item().is_none() {
4926            cursor.next();
4927        }
4928
4929        let mut position = cursor.start().1;
4930        if let Some(excerpt) = cursor.item()
4931            && excerpt.id == anchor.excerpt_id
4932        {
4933            let excerpt_buffer_start = excerpt
4934                .buffer
4935                .offset_for_anchor(&excerpt.range.context.start);
4936            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4937            let buffer_position = cmp::min(
4938                excerpt_buffer_end,
4939                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4940            );
4941            if buffer_position > excerpt_buffer_start {
4942                position.value += buffer_position - excerpt_buffer_start;
4943            }
4944        }
4945        position
4946    }
4947
4948    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
4949        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
4950            excerpt_id = *replacement;
4951        }
4952        excerpt_id
4953    }
4954
4955    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4956    where
4957        D: TextDimension + Ord + Sub<D, Output = D>,
4958        I: 'a + IntoIterator<Item = &'a Anchor>,
4959    {
4960        let mut anchors = anchors.into_iter().peekable();
4961        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
4962        let mut diff_transforms_cursor = self
4963            .diff_transforms
4964            .cursor::<Dimensions<ExcerptDimension<D>, OutputDimension<D>>>(&());
4965        diff_transforms_cursor.next();
4966
4967        let mut summaries = Vec::new();
4968        while let Some(anchor) = anchors.peek() {
4969            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
4970            let excerpt_anchors = iter::from_fn(|| {
4971                let anchor = anchors.peek()?;
4972                if self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id {
4973                    Some(anchors.next().unwrap())
4974                } else {
4975                    None
4976                }
4977            });
4978
4979            let locator = self.excerpt_locator_for_id(excerpt_id);
4980            cursor.seek_forward(locator, Bias::Left);
4981            if cursor.item().is_none() {
4982                cursor.next();
4983            }
4984
4985            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4986            if let Some(excerpt) = cursor.item() {
4987                if excerpt.id != excerpt_id {
4988                    let position = self.resolve_summary_for_anchor(
4989                        &Anchor::min(),
4990                        excerpt_start_position,
4991                        &mut diff_transforms_cursor,
4992                    );
4993                    summaries.extend(excerpt_anchors.map(|_| position));
4994                    continue;
4995                }
4996                let excerpt_buffer_start =
4997                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4998                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4999                for (buffer_summary, anchor) in excerpt
5000                    .buffer
5001                    .summaries_for_anchors_with_payload::<D, _, _>(
5002                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
5003                    )
5004                {
5005                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5006                    let mut position = excerpt_start_position;
5007                    if summary > excerpt_buffer_start {
5008                        position.add_assign(&(summary - excerpt_buffer_start));
5009                    }
5010
5011                    if position > diff_transforms_cursor.start().0.0 {
5012                        diff_transforms_cursor
5013                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5014                    }
5015
5016                    summaries.push(self.resolve_summary_for_anchor(
5017                        anchor,
5018                        position,
5019                        &mut diff_transforms_cursor,
5020                    ));
5021                }
5022            } else {
5023                diff_transforms_cursor
5024                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5025                let position = self.resolve_summary_for_anchor(
5026                    &Anchor::max(),
5027                    excerpt_start_position,
5028                    &mut diff_transforms_cursor,
5029                );
5030                summaries.extend(excerpt_anchors.map(|_| position));
5031            }
5032        }
5033
5034        summaries
5035    }
5036
5037    pub fn dimensions_from_points<'a, D>(
5038        &'a self,
5039        points: impl 'a + IntoIterator<Item = Point>,
5040    ) -> impl 'a + Iterator<Item = D>
5041    where
5042        D: TextDimension + Sub<D, Output = D>,
5043    {
5044        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5045        cursor.seek(&DimensionPair {
5046            key: Point::default(),
5047            value: None,
5048        });
5049        let mut points = points.into_iter();
5050        iter::from_fn(move || {
5051            let point = points.next()?;
5052
5053            cursor.seek_forward(&DimensionPair {
5054                key: point,
5055                value: None,
5056            });
5057
5058            if let Some(region) = cursor.region() {
5059                let overshoot = point - region.range.start.key;
5060                let buffer_point = region.buffer_range.start.key + overshoot;
5061                let mut position = region.range.start.value.unwrap();
5062                position.add_assign(
5063                    &region
5064                        .buffer
5065                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5066                );
5067                if point == region.range.end.key && region.has_trailing_newline {
5068                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5069                }
5070                Some(position)
5071            } else {
5072                Some(D::from_text_summary(&self.text_summary()))
5073            }
5074        })
5075    }
5076
5077    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5078    where
5079        I: 'a + IntoIterator<Item = &'a Anchor>,
5080    {
5081        let mut anchors = anchors.into_iter().enumerate().peekable();
5082        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
5083        cursor.next();
5084
5085        let mut result = Vec::new();
5086
5087        while let Some((_, anchor)) = anchors.peek() {
5088            let old_excerpt_id = anchor.excerpt_id;
5089
5090            // Find the location where this anchor's excerpt should be.
5091            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5092            cursor.seek_forward(&Some(old_locator), Bias::Left);
5093
5094            if cursor.item().is_none() {
5095                cursor.next();
5096            }
5097
5098            let next_excerpt = cursor.item();
5099            let prev_excerpt = cursor.prev_item();
5100
5101            // Process all of the anchors for this excerpt.
5102            while let Some((_, anchor)) = anchors.peek() {
5103                if anchor.excerpt_id != old_excerpt_id {
5104                    break;
5105                }
5106                let (anchor_ix, anchor) = anchors.next().unwrap();
5107                let mut anchor = *anchor;
5108
5109                // Leave min and max anchors unchanged if invalid or
5110                // if the old excerpt still exists at this location
5111                let mut kept_position = next_excerpt
5112                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5113                    || old_excerpt_id == ExcerptId::max()
5114                    || old_excerpt_id == ExcerptId::min();
5115
5116                // If the old excerpt no longer exists at this location, then attempt to
5117                // find an equivalent position for this anchor in an adjacent excerpt.
5118                if !kept_position {
5119                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5120                        if excerpt.contains(&anchor) {
5121                            anchor.excerpt_id = excerpt.id;
5122                            kept_position = true;
5123                            break;
5124                        }
5125                    }
5126                }
5127
5128                // If there's no adjacent excerpt that contains the anchor's position,
5129                // then report that the anchor has lost its position.
5130                if !kept_position {
5131                    anchor = if let Some(excerpt) = next_excerpt {
5132                        let mut text_anchor = excerpt
5133                            .range
5134                            .context
5135                            .start
5136                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5137                        if text_anchor
5138                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5139                            .is_gt()
5140                        {
5141                            text_anchor = excerpt.range.context.end;
5142                        }
5143                        Anchor {
5144                            buffer_id: Some(excerpt.buffer_id),
5145                            excerpt_id: excerpt.id,
5146                            text_anchor,
5147                            diff_base_anchor: None,
5148                        }
5149                    } else if let Some(excerpt) = prev_excerpt {
5150                        let mut text_anchor = excerpt
5151                            .range
5152                            .context
5153                            .end
5154                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5155                        if text_anchor
5156                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5157                            .is_lt()
5158                        {
5159                            text_anchor = excerpt.range.context.start;
5160                        }
5161                        Anchor {
5162                            buffer_id: Some(excerpt.buffer_id),
5163                            excerpt_id: excerpt.id,
5164                            text_anchor,
5165                            diff_base_anchor: None,
5166                        }
5167                    } else if anchor.text_anchor.bias == Bias::Left {
5168                        Anchor::min()
5169                    } else {
5170                        Anchor::max()
5171                    };
5172                }
5173
5174                result.push((anchor_ix, anchor, kept_position));
5175            }
5176        }
5177        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5178        result
5179    }
5180
5181    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5182        self.anchor_at(position, Bias::Left)
5183    }
5184
5185    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5186        self.anchor_at(position, Bias::Right)
5187    }
5188
5189    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5190        let offset = position.to_offset(self);
5191
5192        // Find the given position in the diff transforms. Determine the corresponding
5193        // offset in the excerpts, and whether the position is within a deleted hunk.
5194        let mut diff_transforms = self
5195            .diff_transforms
5196            .cursor::<Dimensions<usize, ExcerptOffset>>(&());
5197        diff_transforms.seek(&offset, Bias::Right);
5198
5199        if offset == diff_transforms.start().0
5200            && bias == Bias::Left
5201            && let Some(prev_item) = diff_transforms.prev_item()
5202            && let DiffTransform::DeletedHunk { .. } = prev_item
5203        {
5204            diff_transforms.prev();
5205        }
5206        let offset_in_transform = offset - diff_transforms.start().0;
5207        let mut excerpt_offset = diff_transforms.start().1;
5208        let mut diff_base_anchor = None;
5209        if let Some(DiffTransform::DeletedHunk {
5210            buffer_id,
5211            base_text_byte_range,
5212            has_trailing_newline,
5213            ..
5214        }) = diff_transforms.item()
5215        {
5216            let diff = self.diffs.get(buffer_id).expect("missing diff");
5217            if offset_in_transform > base_text_byte_range.len() {
5218                debug_assert!(*has_trailing_newline);
5219                bias = Bias::Right;
5220            } else {
5221                diff_base_anchor = Some(
5222                    diff.base_text()
5223                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5224                );
5225                bias = Bias::Left;
5226            }
5227        } else {
5228            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5229        };
5230
5231        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
5232            return Anchor {
5233                buffer_id: Some(buffer_id),
5234                excerpt_id: *excerpt_id,
5235                text_anchor: buffer.anchor_at(excerpt_offset.value, bias),
5236                diff_base_anchor,
5237            };
5238        }
5239
5240        let mut excerpts = self
5241            .excerpts
5242            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(&());
5243        excerpts.seek(&excerpt_offset, Bias::Right);
5244        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5245            excerpts.prev();
5246        }
5247        if let Some(excerpt) = excerpts.item() {
5248            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5249            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5250                overshoot -= 1;
5251                bias = Bias::Right;
5252            }
5253
5254            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5255            let text_anchor =
5256                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5257            Anchor {
5258                buffer_id: Some(excerpt.buffer_id),
5259                excerpt_id: excerpt.id,
5260                text_anchor,
5261                diff_base_anchor,
5262            }
5263        } else if excerpt_offset.is_zero() && bias == Bias::Left {
5264            Anchor::min()
5265        } else {
5266            Anchor::max()
5267        }
5268    }
5269
5270    /// Returns an anchor for the given excerpt and text anchor,
5271    /// returns None if the excerpt_id is no longer valid.
5272    pub fn anchor_in_excerpt(
5273        &self,
5274        excerpt_id: ExcerptId,
5275        text_anchor: text::Anchor,
5276    ) -> Option<Anchor> {
5277        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5278        let locator = self.excerpt_locator_for_id(excerpt_id);
5279        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
5280        cursor.seek(locator, Bias::Left);
5281        if let Some(excerpt) = cursor.item()
5282            && excerpt.id == excerpt_id
5283        {
5284            let text_anchor = excerpt.clip_anchor(text_anchor);
5285            drop(cursor);
5286            return Some(Anchor {
5287                buffer_id: Some(excerpt.buffer_id),
5288                excerpt_id,
5289                text_anchor,
5290                diff_base_anchor: None,
5291            });
5292        }
5293        None
5294    }
5295
5296    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5297        Some(self.excerpt(excerpt_id)?.range.context.clone())
5298    }
5299
5300    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5301        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5302            true
5303        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5304            excerpt.buffer.can_resolve(&anchor.text_anchor)
5305        } else {
5306            false
5307        }
5308    }
5309
5310    pub fn excerpts(
5311        &self,
5312    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5313        self.excerpts
5314            .iter()
5315            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5316    }
5317
5318    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5319        let excerpts = self.excerpts.cursor(&());
5320        let diff_transforms = self.diff_transforms.cursor(&());
5321        MultiBufferCursor {
5322            excerpts,
5323            diff_transforms,
5324            diffs: &self.diffs,
5325            cached_region: None,
5326        }
5327    }
5328
5329    pub fn excerpt_before(&self, id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5330        let start_locator = self.excerpt_locator_for_id(id);
5331        let mut excerpts = self
5332            .excerpts
5333            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(&());
5334        excerpts.seek(&Some(start_locator), Bias::Left);
5335        excerpts.prev();
5336
5337        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(&());
5338        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5339        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5340            diff_transforms.next();
5341        }
5342
5343        let excerpt = excerpts.item()?;
5344        Some(MultiBufferExcerpt {
5345            excerpt,
5346            offset: diff_transforms.start().output_dimension.0,
5347            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5348            excerpt_offset: excerpts.start().1.clone(),
5349            diff_transforms,
5350        })
5351    }
5352
5353    pub fn excerpt_boundaries_in_range<R, T>(
5354        &self,
5355        range: R,
5356    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5357    where
5358        R: RangeBounds<T>,
5359        T: ToOffset,
5360    {
5361        let start_offset;
5362        let start = match range.start_bound() {
5363            Bound::Included(start) => {
5364                start_offset = start.to_offset(self);
5365                Bound::Included(start_offset)
5366            }
5367            Bound::Excluded(_) => {
5368                panic!("not supported")
5369            }
5370            Bound::Unbounded => {
5371                start_offset = 0;
5372                Bound::Unbounded
5373            }
5374        };
5375        let end = match range.end_bound() {
5376            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5377            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5378            Bound::Unbounded => Bound::Unbounded,
5379        };
5380        let bounds = (start, end);
5381
5382        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5383        cursor.seek(&DimensionPair {
5384            key: start_offset,
5385            value: None,
5386        });
5387
5388        if cursor
5389            .region()
5390            .is_some_and(|region| bounds.contains(&region.range.start.key))
5391        {
5392            cursor.prev_excerpt();
5393        } else {
5394            cursor.seek_to_start_of_current_excerpt();
5395        }
5396        let mut prev_region = cursor.region();
5397
5398        cursor.next_excerpt();
5399
5400        iter::from_fn(move || {
5401            loop {
5402                if self.singleton {
5403                    return None;
5404                }
5405
5406                let next_region = cursor.region()?;
5407                cursor.next_excerpt();
5408                if !bounds.contains(&next_region.range.start.key) {
5409                    prev_region = Some(next_region);
5410                    continue;
5411                }
5412
5413                let next_region_start = next_region.range.start.value.unwrap();
5414                let next_region_end = if let Some(region) = cursor.region() {
5415                    region.range.start.value.unwrap()
5416                } else {
5417                    self.max_point()
5418                };
5419
5420                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5421                    id: region.excerpt.id,
5422                    buffer: region.excerpt.buffer.clone(),
5423                    buffer_id: region.excerpt.buffer_id,
5424                    range: region.excerpt.range.clone(),
5425                    end_row: MultiBufferRow(next_region_start.row),
5426                });
5427
5428                let next = ExcerptInfo {
5429                    id: next_region.excerpt.id,
5430                    buffer: next_region.excerpt.buffer.clone(),
5431                    buffer_id: next_region.excerpt.buffer_id,
5432                    range: next_region.excerpt.range.clone(),
5433                    end_row: if next_region.excerpt.has_trailing_newline {
5434                        MultiBufferRow(next_region_end.row - 1)
5435                    } else {
5436                        MultiBufferRow(next_region_end.row)
5437                    },
5438                };
5439
5440                let row = MultiBufferRow(next_region_start.row);
5441
5442                prev_region = Some(next_region);
5443
5444                return Some(ExcerptBoundary { row, prev, next });
5445            }
5446        })
5447    }
5448
5449    pub fn edit_count(&self) -> usize {
5450        self.edit_count
5451    }
5452
5453    pub fn non_text_state_update_count(&self) -> usize {
5454        self.non_text_state_update_count
5455    }
5456
5457    /// Returns the smallest enclosing bracket ranges containing the given range or
5458    /// None if no brackets contain range or the range is not contained in a single
5459    /// excerpt
5460    ///
5461    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5462    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5463        &self,
5464        range: Range<T>,
5465        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5466    ) -> Option<(Range<usize>, Range<usize>)> {
5467        let range = range.start.to_offset(self)..range.end.to_offset(self);
5468        let mut excerpt = self.excerpt_containing(range.clone())?;
5469        let buffer = excerpt.buffer();
5470        let excerpt_buffer_range = excerpt.buffer_range();
5471
5472        // Filter to ranges contained in the excerpt
5473        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5474            excerpt_buffer_range.contains(&open.start)
5475                && excerpt_buffer_range.contains(&close.end)
5476                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5477        };
5478
5479        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5480            excerpt.map_range_to_buffer(range),
5481            Some(&range_filter),
5482        )?;
5483
5484        Some((
5485            excerpt.map_range_from_buffer(open),
5486            excerpt.map_range_from_buffer(close),
5487        ))
5488    }
5489
5490    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5491    /// not contained in a single excerpt
5492    pub fn enclosing_bracket_ranges<T: ToOffset>(
5493        &self,
5494        range: Range<T>,
5495    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5496        let range = range.start.to_offset(self)..range.end.to_offset(self);
5497        let mut excerpt = self.excerpt_containing(range.clone())?;
5498
5499        Some(
5500            excerpt
5501                .buffer()
5502                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5503                .filter_map(move |pair| {
5504                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5505                        Some((
5506                            excerpt.map_range_from_buffer(pair.open_range),
5507                            excerpt.map_range_from_buffer(pair.close_range),
5508                        ))
5509                    } else {
5510                        None
5511                    }
5512                }),
5513        )
5514    }
5515
5516    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5517    /// not contained in a single excerpt
5518    pub fn text_object_ranges<T: ToOffset>(
5519        &self,
5520        range: Range<T>,
5521        options: TreeSitterOptions,
5522    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5523        let range = range.start.to_offset(self)..range.end.to_offset(self);
5524        self.excerpt_containing(range.clone())
5525            .map(|mut excerpt| {
5526                excerpt
5527                    .buffer()
5528                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5529                    .filter_map(move |(range, text_object)| {
5530                        if excerpt.contains_buffer_range(range.clone()) {
5531                            Some((excerpt.map_range_from_buffer(range), text_object))
5532                        } else {
5533                            None
5534                        }
5535                    })
5536            })
5537            .into_iter()
5538            .flatten()
5539    }
5540
5541    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5542    /// not contained in a single excerpt
5543    pub fn bracket_ranges<T: ToOffset>(
5544        &self,
5545        range: Range<T>,
5546    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5547        let range = range.start.to_offset(self)..range.end.to_offset(self);
5548        let mut excerpt = self.excerpt_containing(range.clone())?;
5549
5550        Some(
5551            excerpt
5552                .buffer()
5553                .bracket_ranges(excerpt.map_range_to_buffer(range))
5554                .filter_map(move |pair| {
5555                    let buffer_range = pair.open_range.start..pair.close_range.end;
5556                    if excerpt.contains_buffer_range(buffer_range) {
5557                        Some((
5558                            excerpt.map_range_from_buffer(pair.open_range),
5559                            excerpt.map_range_from_buffer(pair.close_range),
5560                        ))
5561                    } else {
5562                        None
5563                    }
5564                }),
5565        )
5566    }
5567
5568    pub fn redacted_ranges<'a, T: ToOffset>(
5569        &'a self,
5570        range: Range<T>,
5571        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5572    ) -> impl Iterator<Item = Range<usize>> + 'a {
5573        let range = range.start.to_offset(self)..range.end.to_offset(self);
5574        self.lift_buffer_metadata(range, move |buffer, range| {
5575            if redaction_enabled(buffer.file()) {
5576                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5577            } else {
5578                None
5579            }
5580        })
5581        .map(|(range, _, _)| range)
5582    }
5583
5584    pub fn runnable_ranges(
5585        &self,
5586        range: Range<Anchor>,
5587    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5588        let range = range.start.to_offset(self)..range.end.to_offset(self);
5589        self.lift_buffer_metadata(range, move |buffer, range| {
5590            Some(
5591                buffer
5592                    .runnable_ranges(range.clone())
5593                    .filter(move |runnable| {
5594                        runnable.run_range.start >= range.start
5595                            && runnable.run_range.end < range.end
5596                    })
5597                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5598            )
5599        })
5600        .map(|(run_range, runnable, _)| language::RunnableRange {
5601            run_range,
5602            ..runnable
5603        })
5604    }
5605
5606    pub fn line_indents(
5607        &self,
5608        start_row: MultiBufferRow,
5609        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5610    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5611        let max_point = self.max_point();
5612        let mut cursor = self.cursor::<Point>();
5613        cursor.seek(&Point::new(start_row.0, 0));
5614        iter::from_fn(move || {
5615            let mut region = cursor.region()?;
5616            while !buffer_filter(&region.excerpt.buffer) {
5617                cursor.next();
5618                region = cursor.region()?;
5619            }
5620            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5621            let buffer_start_row =
5622                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5623
5624            let buffer_end_row = if region.is_main_buffer
5625                && (region.has_trailing_newline || region.range.end == max_point)
5626            {
5627                region.buffer_range.end.row
5628            } else {
5629                region.buffer_range.end.row.saturating_sub(1)
5630            };
5631
5632            let line_indents = region
5633                .buffer
5634                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5635            cursor.next();
5636            Some(line_indents.map(move |(buffer_row, indent)| {
5637                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5638                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5639            }))
5640        })
5641        .flatten()
5642    }
5643
5644    pub fn reversed_line_indents(
5645        &self,
5646        end_row: MultiBufferRow,
5647        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5648    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5649        let max_point = self.max_point();
5650        let mut cursor = self.cursor::<Point>();
5651        cursor.seek(&Point::new(end_row.0, 0));
5652        iter::from_fn(move || {
5653            let mut region = cursor.region()?;
5654            while !buffer_filter(&region.excerpt.buffer) {
5655                cursor.prev();
5656                region = cursor.region()?;
5657            }
5658
5659            let buffer_start_row = region.buffer_range.start.row;
5660            let buffer_end_row = if region.is_main_buffer
5661                && (region.has_trailing_newline || region.range.end == max_point)
5662            {
5663                region.buffer_range.end.row + 1
5664            } else {
5665                region.buffer_range.end.row
5666            };
5667
5668            let overshoot = end_row.0 - region.range.start.row;
5669            let buffer_end_row =
5670                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5671
5672            let line_indents = region
5673                .buffer
5674                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5675            cursor.prev();
5676            Some(line_indents.map(move |(buffer_row, indent)| {
5677                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5678                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5679            }))
5680        })
5681        .flatten()
5682    }
5683
5684    pub async fn enclosing_indent(
5685        &self,
5686        mut target_row: MultiBufferRow,
5687    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5688        let max_row = MultiBufferRow(self.max_point().row);
5689        if target_row >= max_row {
5690            return None;
5691        }
5692
5693        let mut target_indent = self.line_indent_for_row(target_row);
5694
5695        // If the current row is at the start of an indented block, we want to return this
5696        // block as the enclosing indent.
5697        if !target_indent.is_line_empty() && target_row < max_row {
5698            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5699            if !next_line_indent.is_line_empty()
5700                && target_indent.raw_len() < next_line_indent.raw_len()
5701            {
5702                target_indent = next_line_indent;
5703                target_row.0 += 1;
5704            }
5705        }
5706
5707        const SEARCH_ROW_LIMIT: u32 = 25000;
5708        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5709        const YIELD_INTERVAL: u32 = 100;
5710
5711        let mut accessed_row_counter = 0;
5712
5713        // If there is a blank line at the current row, search for the next non indented lines
5714        if target_indent.is_line_empty() {
5715            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5716            let end =
5717                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5718
5719            let mut non_empty_line_above = None;
5720            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5721                if row < start {
5722                    break;
5723                }
5724                accessed_row_counter += 1;
5725                if accessed_row_counter == YIELD_INTERVAL {
5726                    accessed_row_counter = 0;
5727                    yield_now().await;
5728                }
5729                if !indent.is_line_empty() {
5730                    non_empty_line_above = Some((row, indent));
5731                    break;
5732                }
5733            }
5734
5735            let mut non_empty_line_below = None;
5736            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5737                if row > end {
5738                    break;
5739                }
5740                accessed_row_counter += 1;
5741                if accessed_row_counter == YIELD_INTERVAL {
5742                    accessed_row_counter = 0;
5743                    yield_now().await;
5744                }
5745                if !indent.is_line_empty() {
5746                    non_empty_line_below = Some((row, indent));
5747                    break;
5748                }
5749            }
5750
5751            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5752                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5753                    if above_indent.raw_len() >= below_indent.raw_len() {
5754                        (above_row, above_indent)
5755                    } else {
5756                        (below_row, below_indent)
5757                    }
5758                }
5759                (Some(above), None) => above,
5760                (None, Some(below)) => below,
5761                _ => return None,
5762            };
5763
5764            target_indent = indent;
5765            target_row = row;
5766        }
5767
5768        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5769        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5770
5771        let mut start_indent = None;
5772        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5773            if row < start {
5774                break;
5775            }
5776            accessed_row_counter += 1;
5777            if accessed_row_counter == YIELD_INTERVAL {
5778                accessed_row_counter = 0;
5779                yield_now().await;
5780            }
5781            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5782                start_indent = Some((row, indent));
5783                break;
5784            }
5785        }
5786        let (start_row, start_indent_size) = start_indent?;
5787
5788        let mut end_indent = (end, None);
5789        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5790            if row > end {
5791                break;
5792            }
5793            accessed_row_counter += 1;
5794            if accessed_row_counter == YIELD_INTERVAL {
5795                accessed_row_counter = 0;
5796                yield_now().await;
5797            }
5798            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5799                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5800                break;
5801            }
5802        }
5803        let (end_row, end_indent_size) = end_indent;
5804
5805        let indent = if let Some(end_indent_size) = end_indent_size {
5806            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5807                start_indent_size
5808            } else {
5809                end_indent_size
5810            }
5811        } else {
5812            start_indent_size
5813        };
5814
5815        Some((start_row..end_row, indent))
5816    }
5817
5818    pub fn indent_guides_in_range<T: ToPoint>(
5819        &self,
5820        range: Range<T>,
5821        ignore_disabled_for_language: bool,
5822        cx: &App,
5823    ) -> impl Iterator<Item = IndentGuide> {
5824        let range = range.start.to_point(self)..range.end.to_point(self);
5825        let start_row = MultiBufferRow(range.start.row);
5826        let end_row = MultiBufferRow(range.end.row);
5827
5828        let mut row_indents = self.line_indents(start_row, |buffer| {
5829            let settings =
5830                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5831            settings.indent_guides.enabled || ignore_disabled_for_language
5832        });
5833
5834        let mut result = Vec::new();
5835        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5836
5837        let mut prev_settings = None;
5838        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5839            if first_row > end_row {
5840                break;
5841            }
5842            let current_depth = indent_stack.len() as u32;
5843
5844            // Avoid retrieving the language settings repeatedly for every buffer row.
5845            if let Some((prev_buffer_id, _)) = &prev_settings
5846                && prev_buffer_id != &buffer.remote_id()
5847            {
5848                prev_settings.take();
5849            }
5850            let settings = &prev_settings
5851                .get_or_insert_with(|| {
5852                    (
5853                        buffer.remote_id(),
5854                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5855                    )
5856                })
5857                .1;
5858            let tab_size = settings.tab_size.get();
5859
5860            // When encountering empty, continue until found useful line indent
5861            // then add to the indent stack with the depth found
5862            let mut found_indent = false;
5863            let mut last_row = first_row;
5864            if line_indent.is_line_blank() {
5865                while !found_indent {
5866                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5867                        break;
5868                    };
5869                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5870                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5871                        break;
5872                    }
5873
5874                    if new_line_indent.is_line_blank() {
5875                        continue;
5876                    }
5877                    last_row = target_row.min(end_row);
5878                    line_indent = new_line_indent;
5879                    found_indent = true;
5880                    break;
5881                }
5882            } else {
5883                found_indent = true
5884            }
5885
5886            let depth = if found_indent {
5887                line_indent.len(tab_size) / tab_size
5888            } else {
5889                0
5890            };
5891
5892            match depth.cmp(&current_depth) {
5893                cmp::Ordering::Less => {
5894                    for _ in 0..(current_depth - depth) {
5895                        let mut indent = indent_stack.pop().unwrap();
5896                        if last_row != first_row {
5897                            // In this case, we landed on an empty row, had to seek forward,
5898                            // and discovered that the indent we where on is ending.
5899                            // This means that the last display row must
5900                            // be on line that ends this indent range, so we
5901                            // should display the range up to the first non-empty line
5902                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5903                        }
5904
5905                        result.push(indent)
5906                    }
5907                }
5908                cmp::Ordering::Greater => {
5909                    for next_depth in current_depth..depth {
5910                        indent_stack.push(IndentGuide {
5911                            buffer_id: buffer.remote_id(),
5912                            start_row: first_row,
5913                            end_row: last_row,
5914                            depth: next_depth,
5915                            tab_size,
5916                            settings: settings.indent_guides,
5917                        });
5918                    }
5919                }
5920                _ => {}
5921            }
5922
5923            for indent in indent_stack.iter_mut() {
5924                indent.end_row = last_row;
5925            }
5926        }
5927
5928        result.extend(indent_stack);
5929        result.into_iter()
5930    }
5931
5932    pub fn trailing_excerpt_update_count(&self) -> usize {
5933        self.trailing_excerpt_update_count
5934    }
5935
5936    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5937        self.point_to_buffer_offset(point)
5938            .and_then(|(buffer, _)| buffer.file())
5939    }
5940
5941    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5942        self.point_to_buffer_offset(point)
5943            .and_then(|(buffer, offset)| buffer.language_at(offset))
5944    }
5945
5946    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5947        self.excerpts
5948            .first()
5949            .map(|excerpt| &excerpt.buffer)
5950            .map(|buffer| {
5951                language_settings(
5952                    buffer.language().map(|language| language.name()),
5953                    buffer.file(),
5954                    cx,
5955                )
5956            })
5957            .unwrap_or_else(move || self.language_settings_at(0, cx))
5958    }
5959
5960    pub fn language_settings_at<'a, T: ToOffset>(
5961        &'a self,
5962        point: T,
5963        cx: &'a App,
5964    ) -> Cow<'a, LanguageSettings> {
5965        let mut language = None;
5966        let mut file = None;
5967        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5968            language = buffer.language_at(offset);
5969            file = buffer.file();
5970        }
5971        language_settings(language.map(|l| l.name()), file, cx)
5972    }
5973
5974    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5975        self.point_to_buffer_offset(point)
5976            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5977    }
5978
5979    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5980        self.point_to_buffer_offset(point)
5981            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5982            .unwrap_or_default()
5983    }
5984
5985    pub fn language_indent_size_at<T: ToOffset>(
5986        &self,
5987        position: T,
5988        cx: &App,
5989    ) -> Option<IndentSize> {
5990        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5991        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5992    }
5993
5994    pub fn is_dirty(&self) -> bool {
5995        self.is_dirty
5996    }
5997
5998    pub fn has_deleted_file(&self) -> bool {
5999        self.has_deleted_file
6000    }
6001
6002    pub fn has_conflict(&self) -> bool {
6003        self.has_conflict
6004    }
6005
6006    pub fn has_diagnostics(&self) -> bool {
6007        self.excerpts
6008            .iter()
6009            .any(|excerpt| excerpt.buffer.has_diagnostics())
6010    }
6011
6012    pub fn diagnostic_group(
6013        &self,
6014        buffer_id: BufferId,
6015        group_id: usize,
6016    ) -> impl Iterator<Item = DiagnosticEntry<Point>> + '_ {
6017        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
6018            if buffer.remote_id() != buffer_id {
6019                return None;
6020            };
6021            Some(
6022                buffer
6023                    .diagnostics_in_range(range, false)
6024                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
6025                    .map(move |DiagnosticEntry { diagnostic, range }| (range, diagnostic)),
6026            )
6027        })
6028        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
6029    }
6030
6031    pub fn diagnostics_in_range<'a, T>(
6032        &'a self,
6033        range: Range<T>,
6034    ) -> impl Iterator<Item = DiagnosticEntry<T>> + 'a
6035    where
6036        T: 'a
6037            + text::ToOffset
6038            + text::FromAnchor
6039            + TextDimension
6040            + Ord
6041            + Sub<T, Output = T>
6042            + fmt::Debug,
6043    {
6044        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6045            Some(
6046                buffer
6047                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6048                    .map(|entry| (entry.range, entry.diagnostic)),
6049            )
6050        })
6051        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
6052    }
6053
6054    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6055        &'a self,
6056        range: Range<T>,
6057    ) -> impl Iterator<Item = (BufferId, DiagnosticEntry<T>)> + 'a
6058    where
6059        T: 'a
6060            + text::ToOffset
6061            + text::FromAnchor
6062            + TextDimension
6063            + Ord
6064            + Sub<T, Output = T>
6065            + fmt::Debug,
6066    {
6067        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6068            Some(
6069                buffer
6070                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6071                    .map(|entry| (entry.range, entry.diagnostic)),
6072            )
6073        })
6074        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntry { diagnostic, range }))
6075    }
6076
6077    pub fn syntax_ancestor<T: ToOffset>(
6078        &self,
6079        range: Range<T>,
6080    ) -> Option<(tree_sitter::Node<'_>, MultiOrSingleBufferOffsetRange)> {
6081        let range = range.start.to_offset(self)..range.end.to_offset(self);
6082        let mut excerpt = self.excerpt_containing(range.clone())?;
6083        let node = excerpt
6084            .buffer()
6085            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6086        let node_range = node.byte_range();
6087        let range = if excerpt.contains_buffer_range(node_range.clone()) {
6088            MultiOrSingleBufferOffsetRange::Multi(excerpt.map_range_from_buffer(node_range))
6089        } else {
6090            MultiOrSingleBufferOffsetRange::Single(node_range)
6091        };
6092        Some((node, range))
6093    }
6094
6095    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6096        let (excerpt_id, _, buffer) = self.as_singleton()?;
6097        let outline = buffer.outline(theme)?;
6098        Some(Outline::new(
6099            outline
6100                .items
6101                .into_iter()
6102                .flat_map(|item| {
6103                    Some(OutlineItem {
6104                        depth: item.depth,
6105                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6106                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6107                        text: item.text,
6108                        highlight_ranges: item.highlight_ranges,
6109                        name_ranges: item.name_ranges,
6110                        body_range: item.body_range.and_then(|body_range| {
6111                            Some(
6112                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6113                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6114                            )
6115                        }),
6116                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6117                            Some(
6118                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6119                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6120                            )
6121                        }),
6122                    })
6123                })
6124                .collect(),
6125        ))
6126    }
6127
6128    pub fn symbols_containing<T: ToOffset>(
6129        &self,
6130        offset: T,
6131        theme: Option<&SyntaxTheme>,
6132    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6133        let anchor = self.anchor_before(offset);
6134        let excerpt_id = anchor.excerpt_id;
6135        let excerpt = self.excerpt(excerpt_id)?;
6136        Some((
6137            excerpt.buffer_id,
6138            excerpt
6139                .buffer
6140                .symbols_containing(anchor.text_anchor, theme)
6141                .into_iter()
6142                .flatten()
6143                .flat_map(|item| {
6144                    Some(OutlineItem {
6145                        depth: item.depth,
6146                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
6147                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
6148                        text: item.text,
6149                        highlight_ranges: item.highlight_ranges,
6150                        name_ranges: item.name_ranges,
6151                        body_range: item.body_range.and_then(|body_range| {
6152                            Some(
6153                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
6154                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
6155                            )
6156                        }),
6157                        annotation_range: item.annotation_range.and_then(|body_range| {
6158                            Some(
6159                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
6160                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
6161                            )
6162                        }),
6163                    })
6164                })
6165                .collect(),
6166        ))
6167    }
6168
6169    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6170        if id == ExcerptId::min() {
6171            Locator::min_ref()
6172        } else if id == ExcerptId::max() {
6173            Locator::max_ref()
6174        } else {
6175            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
6176            cursor.seek(&id, Bias::Left);
6177            if let Some(entry) = cursor.item()
6178                && entry.id == id
6179            {
6180                return &entry.locator;
6181            }
6182            panic!("invalid excerpt id {id:?}")
6183        }
6184    }
6185
6186    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6187    fn excerpt_locators_for_ids(
6188        &self,
6189        ids: impl IntoIterator<Item = ExcerptId>,
6190    ) -> SmallVec<[Locator; 1]> {
6191        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6192        sorted_ids.sort_unstable();
6193        let mut locators = SmallVec::new();
6194
6195        while sorted_ids.last() == Some(&ExcerptId::max()) {
6196            sorted_ids.pop();
6197            if let Some(mapping) = self.excerpt_ids.last() {
6198                locators.push(mapping.locator.clone());
6199            }
6200        }
6201
6202        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6203        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6204            sorted_ids.next();
6205            if let Some(mapping) = self.excerpt_ids.first() {
6206                locators.push(mapping.locator.clone());
6207            }
6208        }
6209
6210        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
6211        for id in sorted_ids {
6212            if cursor.seek_forward(&id, Bias::Left) {
6213                locators.push(cursor.item().unwrap().locator.clone());
6214            } else {
6215                panic!("invalid excerpt id {:?}", id);
6216            }
6217        }
6218
6219        locators.sort_unstable();
6220        locators
6221    }
6222
6223    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6224        Some(self.excerpt(excerpt_id)?.buffer_id)
6225    }
6226
6227    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6228        Some(&self.excerpt(excerpt_id)?.buffer)
6229    }
6230
6231    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6232        let mut cursor = self
6233            .excerpts
6234            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(&());
6235        let locator = self.excerpt_locator_for_id(excerpt_id);
6236        if cursor.seek(&Some(locator), Bias::Left) {
6237            let start = cursor.start().1.clone();
6238            let end = cursor.end().1;
6239            let mut diff_transforms = self
6240                .diff_transforms
6241                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(&());
6242            diff_transforms.seek(&start, Bias::Left);
6243            let overshoot = start.0 - diff_transforms.start().0.0;
6244            let start = diff_transforms.start().1.0 + overshoot;
6245            diff_transforms.seek(&end, Bias::Right);
6246            let overshoot = end.0 - diff_transforms.start().0.0;
6247            let end = diff_transforms.start().1.0 + overshoot;
6248            Some(start..end)
6249        } else {
6250            None
6251        }
6252    }
6253
6254    pub fn buffer_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
6255        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
6256        let locator = self.excerpt_locator_for_id(excerpt_id);
6257        if cursor.seek(&Some(locator), Bias::Left)
6258            && let Some(excerpt) = cursor.item()
6259        {
6260            return Some(excerpt.range.context.clone());
6261        }
6262        None
6263    }
6264
6265    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6266        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
6267        let locator = self.excerpt_locator_for_id(excerpt_id);
6268        cursor.seek(&Some(locator), Bias::Left);
6269        if let Some(excerpt) = cursor.item()
6270            && excerpt.id == excerpt_id
6271        {
6272            return Some(excerpt);
6273        }
6274        None
6275    }
6276
6277    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6278    pub fn excerpt_containing<T: ToOffset>(
6279        &self,
6280        range: Range<T>,
6281    ) -> Option<MultiBufferExcerpt<'_>> {
6282        let range = range.start.to_offset(self)..range.end.to_offset(self);
6283        let mut cursor = self.cursor::<usize>();
6284        cursor.seek(&range.start);
6285
6286        let start_excerpt = cursor.excerpt()?;
6287        if range.end != range.start {
6288            cursor.seek_forward(&range.end);
6289            if cursor.excerpt()?.id != start_excerpt.id {
6290                return None;
6291            }
6292        }
6293
6294        cursor.seek_to_start_of_current_excerpt();
6295        let region = cursor.region()?;
6296        let offset = region.range.start;
6297        let buffer_offset = start_excerpt.buffer_start_offset();
6298        let excerpt_offset = cursor.excerpts.start().clone();
6299        Some(MultiBufferExcerpt {
6300            diff_transforms: cursor.diff_transforms,
6301            excerpt: start_excerpt,
6302            offset,
6303            buffer_offset,
6304            excerpt_offset,
6305        })
6306    }
6307
6308    pub fn selections_in_range<'a>(
6309        &'a self,
6310        range: &'a Range<Anchor>,
6311        include_local: bool,
6312    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6313        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
6314        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6315        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6316        cursor.seek(start_locator, Bias::Left);
6317        cursor
6318            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6319            .flat_map(move |excerpt| {
6320                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6321                if excerpt.id == range.start.excerpt_id {
6322                    query_range.start = range.start.text_anchor;
6323                }
6324                if excerpt.id == range.end.excerpt_id {
6325                    query_range.end = range.end.text_anchor;
6326                }
6327
6328                excerpt
6329                    .buffer
6330                    .selections_in_range(query_range, include_local)
6331                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6332                        selections.map(move |selection| {
6333                            let mut start = Anchor {
6334                                buffer_id: Some(excerpt.buffer_id),
6335                                excerpt_id: excerpt.id,
6336                                text_anchor: selection.start,
6337                                diff_base_anchor: None,
6338                            };
6339                            let mut end = Anchor {
6340                                buffer_id: Some(excerpt.buffer_id),
6341                                excerpt_id: excerpt.id,
6342                                text_anchor: selection.end,
6343                                diff_base_anchor: None,
6344                            };
6345                            if range.start.cmp(&start, self).is_gt() {
6346                                start = range.start;
6347                            }
6348                            if range.end.cmp(&end, self).is_lt() {
6349                                end = range.end;
6350                            }
6351
6352                            (
6353                                replica_id,
6354                                line_mode,
6355                                cursor_shape,
6356                                Selection {
6357                                    id: selection.id,
6358                                    start,
6359                                    end,
6360                                    reversed: selection.reversed,
6361                                    goal: selection.goal,
6362                                },
6363                            )
6364                        })
6365                    })
6366            })
6367    }
6368
6369    pub fn show_headers(&self) -> bool {
6370        self.show_headers
6371    }
6372
6373    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6374        self.diffs.get(&buffer_id)
6375    }
6376}
6377
6378#[cfg(any(test, feature = "test-support"))]
6379impl MultiBufferSnapshot {
6380    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6381        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
6382        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
6383        start..end
6384    }
6385
6386    #[cfg(any(test, feature = "test-support"))]
6387    fn check_invariants(&self) {
6388        let excerpts = self.excerpts.items(&());
6389        let excerpt_ids = self.excerpt_ids.items(&());
6390
6391        for (ix, excerpt) in excerpts.iter().enumerate() {
6392            if ix == 0 {
6393                if excerpt.locator <= Locator::min() {
6394                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6395                }
6396            } else if excerpt.locator <= excerpts[ix - 1].locator {
6397                panic!("excerpts are out-of-order: {:?}", excerpts);
6398            }
6399        }
6400
6401        for (ix, entry) in excerpt_ids.iter().enumerate() {
6402            if ix == 0 {
6403                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6404                    panic!("invalid first excerpt id {:?}", entry.id);
6405                }
6406            } else if entry.id <= excerpt_ids[ix - 1].id {
6407                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6408            }
6409        }
6410
6411        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6412            panic!(
6413                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6414                self.excerpts.summary().text.len,
6415                self.diff_transforms.summary().input,
6416                self.diff_transforms.items(&()),
6417            );
6418        }
6419
6420        let mut prev_transform: Option<&DiffTransform> = None;
6421        for item in self.diff_transforms.iter() {
6422            if let DiffTransform::BufferContent {
6423                summary,
6424                inserted_hunk_info,
6425            } = item
6426            {
6427                if let Some(DiffTransform::BufferContent {
6428                    inserted_hunk_info: prev_inserted_hunk_info,
6429                    ..
6430                }) = prev_transform
6431                    && *inserted_hunk_info == *prev_inserted_hunk_info
6432                {
6433                    panic!(
6434                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6435                        self.diff_transforms.items(&())
6436                    );
6437                }
6438                if summary.len == 0 && !self.is_empty() {
6439                    panic!("empty buffer content transform");
6440                }
6441            }
6442            prev_transform = Some(item);
6443        }
6444    }
6445}
6446
6447impl<'a, D> MultiBufferCursor<'a, D>
6448where
6449    D: TextDimension + Ord + Sub<D, Output = D>,
6450{
6451    fn seek(&mut self, position: &D) {
6452        self.cached_region.take();
6453        self.diff_transforms
6454            .seek(&OutputDimension(*position), Bias::Right);
6455        if self.diff_transforms.item().is_none()
6456            && *position == self.diff_transforms.start().output_dimension.0
6457        {
6458            self.diff_transforms.prev();
6459        }
6460
6461        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6462        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6463            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6464            excerpt_position.add_assign(&overshoot);
6465        }
6466
6467        self.excerpts
6468            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6469        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6470            self.excerpts.prev();
6471        }
6472    }
6473
6474    fn seek_forward(&mut self, position: &D) {
6475        self.cached_region.take();
6476        self.diff_transforms
6477            .seek_forward(&OutputDimension(*position), Bias::Right);
6478        if self.diff_transforms.item().is_none()
6479            && *position == self.diff_transforms.start().output_dimension.0
6480        {
6481            self.diff_transforms.prev();
6482        }
6483
6484        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6485        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6486        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6487            excerpt_position.add_assign(&overshoot);
6488        }
6489
6490        self.excerpts
6491            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6492        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6493            self.excerpts.prev();
6494        }
6495    }
6496
6497    fn next_excerpt(&mut self) {
6498        self.excerpts.next();
6499        self.seek_to_start_of_current_excerpt();
6500    }
6501
6502    fn prev_excerpt(&mut self) {
6503        self.excerpts.prev();
6504        self.seek_to_start_of_current_excerpt();
6505    }
6506
6507    fn seek_to_start_of_current_excerpt(&mut self) {
6508        self.cached_region.take();
6509        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6510        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6511            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6512            && self.diff_transforms.next_item().is_some()
6513        {
6514            self.diff_transforms.next();
6515        }
6516    }
6517
6518    fn next(&mut self) {
6519        self.cached_region.take();
6520        match self
6521            .diff_transforms
6522            .end()
6523            .excerpt_dimension
6524            .cmp(&self.excerpts.end())
6525        {
6526            cmp::Ordering::Less => self.diff_transforms.next(),
6527            cmp::Ordering::Greater => self.excerpts.next(),
6528            cmp::Ordering::Equal => {
6529                self.diff_transforms.next();
6530                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6531                    || self.diff_transforms.item().is_none()
6532                {
6533                    self.excerpts.next();
6534                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6535                    self.diff_transforms.item()
6536                    && self
6537                        .excerpts
6538                        .item()
6539                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6540                {
6541                    self.excerpts.next();
6542                }
6543            }
6544        }
6545    }
6546
6547    fn prev(&mut self) {
6548        self.cached_region.take();
6549        match self
6550            .diff_transforms
6551            .start()
6552            .excerpt_dimension
6553            .cmp(self.excerpts.start())
6554        {
6555            cmp::Ordering::Less => self.excerpts.prev(),
6556            cmp::Ordering::Greater => self.diff_transforms.prev(),
6557            cmp::Ordering::Equal => {
6558                self.diff_transforms.prev();
6559                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6560                    || self.diff_transforms.item().is_none()
6561                {
6562                    self.excerpts.prev();
6563                }
6564            }
6565        }
6566    }
6567
6568    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6569        if self.cached_region.is_none() {
6570            self.cached_region = self.build_region();
6571        }
6572        self.cached_region.clone()
6573    }
6574
6575    fn is_at_start_of_excerpt(&mut self) -> bool {
6576        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6577            return false;
6578        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6579            return true;
6580        }
6581
6582        self.diff_transforms.prev();
6583        let prev_transform = self.diff_transforms.item();
6584        self.diff_transforms.next();
6585
6586        prev_transform.is_none_or(|next_transform| {
6587            matches!(next_transform, DiffTransform::BufferContent { .. })
6588        })
6589    }
6590
6591    fn is_at_end_of_excerpt(&mut self) -> bool {
6592        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6593            return false;
6594        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6595            || self.diff_transforms.item().is_none()
6596        {
6597            return true;
6598        }
6599
6600        let next_transform = self.diff_transforms.next_item();
6601        next_transform.is_none_or(|next_transform| match next_transform {
6602            DiffTransform::BufferContent { .. } => true,
6603            DiffTransform::DeletedHunk { hunk_info, .. } => self
6604                .excerpts
6605                .item()
6606                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6607        })
6608    }
6609
6610    fn main_buffer_position(&self) -> Option<D> {
6611        let excerpt = self.excerpts.item()?;
6612        let buffer = &excerpt.buffer;
6613        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6614        let mut buffer_start = buffer_context_start;
6615        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6616        buffer_start.add_assign(&overshoot);
6617        Some(buffer_start)
6618    }
6619
6620    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6621        let excerpt = self.excerpts.item()?;
6622        match self.diff_transforms.item()? {
6623            DiffTransform::DeletedHunk {
6624                buffer_id,
6625                base_text_byte_range,
6626                has_trailing_newline,
6627                hunk_info,
6628                ..
6629            } => {
6630                let diff = self.diffs.get(buffer_id)?;
6631                let buffer = diff.base_text();
6632                let mut rope_cursor = buffer.as_rope().cursor(0);
6633                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6634                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6635                let mut buffer_end = buffer_start;
6636                buffer_end.add_assign(&buffer_range_len);
6637                let start = self.diff_transforms.start().output_dimension.0;
6638                let end = self.diff_transforms.end().output_dimension.0;
6639                Some(MultiBufferRegion {
6640                    buffer,
6641                    excerpt,
6642                    has_trailing_newline: *has_trailing_newline,
6643                    is_main_buffer: false,
6644                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6645                        hunk_info.hunk_secondary_status,
6646                    )),
6647                    buffer_range: buffer_start..buffer_end,
6648                    range: start..end,
6649                })
6650            }
6651            DiffTransform::BufferContent {
6652                inserted_hunk_info, ..
6653            } => {
6654                let buffer = &excerpt.buffer;
6655                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6656
6657                let mut start = self.diff_transforms.start().output_dimension.0;
6658                let mut buffer_start = buffer_context_start;
6659                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6660                    let overshoot =
6661                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6662                    start.add_assign(&overshoot);
6663                } else {
6664                    let overshoot =
6665                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6666                    buffer_start.add_assign(&overshoot);
6667                }
6668
6669                let mut end;
6670                let mut buffer_end;
6671                let has_trailing_newline;
6672                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6673                    let overshoot =
6674                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6675                    end = self.diff_transforms.end().output_dimension.0;
6676                    buffer_end = buffer_context_start;
6677                    buffer_end.add_assign(&overshoot);
6678                    has_trailing_newline = false;
6679                } else {
6680                    let overshoot =
6681                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6682                    end = self.diff_transforms.start().output_dimension.0;
6683                    end.add_assign(&overshoot);
6684                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6685                    has_trailing_newline = excerpt.has_trailing_newline;
6686                };
6687
6688                Some(MultiBufferRegion {
6689                    buffer,
6690                    excerpt,
6691                    has_trailing_newline,
6692                    is_main_buffer: true,
6693                    diff_hunk_status: inserted_hunk_info
6694                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6695                    buffer_range: buffer_start..buffer_end,
6696                    range: start..end,
6697                })
6698            }
6699        }
6700    }
6701
6702    fn excerpt(&self) -> Option<&'a Excerpt> {
6703        self.excerpts.item()
6704    }
6705}
6706
6707impl History {
6708    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6709        self.transaction_depth += 1;
6710        if self.transaction_depth == 1 {
6711            let id = self.next_transaction_id.tick();
6712            self.undo_stack.push(Transaction {
6713                id,
6714                buffer_transactions: Default::default(),
6715                first_edit_at: now,
6716                last_edit_at: now,
6717                suppress_grouping: false,
6718            });
6719            Some(id)
6720        } else {
6721            None
6722        }
6723    }
6724
6725    fn end_transaction(
6726        &mut self,
6727        now: Instant,
6728        buffer_transactions: HashMap<BufferId, TransactionId>,
6729    ) -> bool {
6730        assert_ne!(self.transaction_depth, 0);
6731        self.transaction_depth -= 1;
6732        if self.transaction_depth == 0 {
6733            if buffer_transactions.is_empty() {
6734                self.undo_stack.pop();
6735                false
6736            } else {
6737                self.redo_stack.clear();
6738                let transaction = self.undo_stack.last_mut().unwrap();
6739                transaction.last_edit_at = now;
6740                for (buffer_id, transaction_id) in buffer_transactions {
6741                    transaction
6742                        .buffer_transactions
6743                        .entry(buffer_id)
6744                        .or_insert(transaction_id);
6745                }
6746                true
6747            }
6748        } else {
6749            false
6750        }
6751    }
6752
6753    fn push_transaction<'a, T>(
6754        &mut self,
6755        buffer_transactions: T,
6756        now: Instant,
6757        cx: &Context<MultiBuffer>,
6758    ) where
6759        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6760    {
6761        assert_eq!(self.transaction_depth, 0);
6762        let transaction = Transaction {
6763            id: self.next_transaction_id.tick(),
6764            buffer_transactions: buffer_transactions
6765                .into_iter()
6766                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6767                .collect(),
6768            first_edit_at: now,
6769            last_edit_at: now,
6770            suppress_grouping: false,
6771        };
6772        if !transaction.buffer_transactions.is_empty() {
6773            self.undo_stack.push(transaction);
6774            self.redo_stack.clear();
6775        }
6776    }
6777
6778    fn finalize_last_transaction(&mut self) {
6779        if let Some(transaction) = self.undo_stack.last_mut() {
6780            transaction.suppress_grouping = true;
6781        }
6782    }
6783
6784    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6785        if let Some(ix) = self
6786            .undo_stack
6787            .iter()
6788            .rposition(|transaction| transaction.id == transaction_id)
6789        {
6790            Some(self.undo_stack.remove(ix))
6791        } else if let Some(ix) = self
6792            .redo_stack
6793            .iter()
6794            .rposition(|transaction| transaction.id == transaction_id)
6795        {
6796            Some(self.redo_stack.remove(ix))
6797        } else {
6798            None
6799        }
6800    }
6801
6802    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6803        self.undo_stack
6804            .iter()
6805            .find(|transaction| transaction.id == transaction_id)
6806            .or_else(|| {
6807                self.redo_stack
6808                    .iter()
6809                    .find(|transaction| transaction.id == transaction_id)
6810            })
6811    }
6812
6813    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6814        self.undo_stack
6815            .iter_mut()
6816            .find(|transaction| transaction.id == transaction_id)
6817            .or_else(|| {
6818                self.redo_stack
6819                    .iter_mut()
6820                    .find(|transaction| transaction.id == transaction_id)
6821            })
6822    }
6823
6824    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6825        assert_eq!(self.transaction_depth, 0);
6826        if let Some(transaction) = self.undo_stack.pop() {
6827            self.redo_stack.push(transaction);
6828            self.redo_stack.last_mut()
6829        } else {
6830            None
6831        }
6832    }
6833
6834    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6835        assert_eq!(self.transaction_depth, 0);
6836        if let Some(transaction) = self.redo_stack.pop() {
6837            self.undo_stack.push(transaction);
6838            self.undo_stack.last_mut()
6839        } else {
6840            None
6841        }
6842    }
6843
6844    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6845        let ix = self
6846            .undo_stack
6847            .iter()
6848            .rposition(|transaction| transaction.id == transaction_id)?;
6849        let transaction = self.undo_stack.remove(ix);
6850        self.redo_stack.push(transaction);
6851        self.redo_stack.last()
6852    }
6853
6854    fn group(&mut self) -> Option<TransactionId> {
6855        let mut count = 0;
6856        let mut transactions = self.undo_stack.iter();
6857        if let Some(mut transaction) = transactions.next_back() {
6858            while let Some(prev_transaction) = transactions.next_back() {
6859                if !prev_transaction.suppress_grouping
6860                    && transaction.first_edit_at - prev_transaction.last_edit_at
6861                        <= self.group_interval
6862                {
6863                    transaction = prev_transaction;
6864                    count += 1;
6865                } else {
6866                    break;
6867                }
6868            }
6869        }
6870        self.group_trailing(count)
6871    }
6872
6873    fn group_until(&mut self, transaction_id: TransactionId) {
6874        let mut count = 0;
6875        for transaction in self.undo_stack.iter().rev() {
6876            if transaction.id == transaction_id {
6877                self.group_trailing(count);
6878                break;
6879            } else if transaction.suppress_grouping {
6880                break;
6881            } else {
6882                count += 1;
6883            }
6884        }
6885    }
6886
6887    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6888        let new_len = self.undo_stack.len() - n;
6889        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6890        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6891            if let Some(transaction) = transactions_to_merge.last() {
6892                last_transaction.last_edit_at = transaction.last_edit_at;
6893            }
6894            for to_merge in transactions_to_merge {
6895                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6896                    last_transaction
6897                        .buffer_transactions
6898                        .entry(*buffer_id)
6899                        .or_insert(*transaction_id);
6900                }
6901            }
6902        }
6903
6904        self.undo_stack.truncate(new_len);
6905        self.undo_stack.last().map(|t| t.id)
6906    }
6907}
6908
6909impl Excerpt {
6910    fn new(
6911        id: ExcerptId,
6912        locator: Locator,
6913        buffer_id: BufferId,
6914        buffer: BufferSnapshot,
6915        range: ExcerptRange<text::Anchor>,
6916        has_trailing_newline: bool,
6917    ) -> Self {
6918        Excerpt {
6919            id,
6920            locator,
6921            max_buffer_row: range.context.end.to_point(&buffer).row,
6922            text_summary: buffer
6923                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6924            buffer_id,
6925            buffer,
6926            range,
6927            has_trailing_newline,
6928        }
6929    }
6930
6931    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6932        let content_start = self.range.context.start.to_offset(&self.buffer);
6933        let chunks_start = content_start + range.start;
6934        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6935
6936        let footer_height = if self.has_trailing_newline
6937            && range.start <= self.text_summary.len
6938            && range.end > self.text_summary.len
6939        {
6940            1
6941        } else {
6942            0
6943        };
6944
6945        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
6946
6947        ExcerptChunks {
6948            excerpt_id: self.id,
6949            content_chunks,
6950            footer_height,
6951        }
6952    }
6953
6954    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
6955        let content_start = self.range.context.start.to_offset(&self.buffer);
6956        let chunks_start = content_start + range.start;
6957        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6958        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
6959        excerpt_chunks.footer_height = if self.has_trailing_newline
6960            && range.start <= self.text_summary.len
6961            && range.end > self.text_summary.len
6962        {
6963            1
6964        } else {
6965            0
6966        };
6967    }
6968
6969    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
6970        if text_anchor
6971            .cmp(&self.range.context.start, &self.buffer)
6972            .is_lt()
6973        {
6974            self.range.context.start
6975        } else if text_anchor
6976            .cmp(&self.range.context.end, &self.buffer)
6977            .is_gt()
6978        {
6979            self.range.context.end
6980        } else {
6981            text_anchor
6982        }
6983    }
6984
6985    fn contains(&self, anchor: &Anchor) -> bool {
6986        Some(self.buffer_id) == anchor.buffer_id
6987            && self
6988                .range
6989                .context
6990                .start
6991                .cmp(&anchor.text_anchor, &self.buffer)
6992                .is_le()
6993            && self
6994                .range
6995                .context
6996                .end
6997                .cmp(&anchor.text_anchor, &self.buffer)
6998                .is_ge()
6999    }
7000
7001    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7002    fn buffer_start_offset(&self) -> usize {
7003        self.range.context.start.to_offset(&self.buffer)
7004    }
7005
7006    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7007    fn buffer_end_offset(&self) -> usize {
7008        self.buffer_start_offset() + self.text_summary.len
7009    }
7010}
7011
7012impl<'a> MultiBufferExcerpt<'a> {
7013    pub fn id(&self) -> ExcerptId {
7014        self.excerpt.id
7015    }
7016
7017    pub fn buffer_id(&self) -> BufferId {
7018        self.excerpt.buffer_id
7019    }
7020
7021    pub fn start_anchor(&self) -> Anchor {
7022        Anchor {
7023            buffer_id: Some(self.excerpt.buffer_id),
7024            excerpt_id: self.excerpt.id,
7025            text_anchor: self.excerpt.range.context.start,
7026            diff_base_anchor: None,
7027        }
7028    }
7029
7030    pub fn end_anchor(&self) -> Anchor {
7031        Anchor {
7032            buffer_id: Some(self.excerpt.buffer_id),
7033            excerpt_id: self.excerpt.id,
7034            text_anchor: self.excerpt.range.context.end,
7035            diff_base_anchor: None,
7036        }
7037    }
7038
7039    pub fn buffer(&self) -> &'a BufferSnapshot {
7040        &self.excerpt.buffer
7041    }
7042
7043    pub fn buffer_range(&self) -> Range<usize> {
7044        self.buffer_offset
7045            ..self
7046                .excerpt
7047                .range
7048                .context
7049                .end
7050                .to_offset(&self.excerpt.buffer.text)
7051    }
7052
7053    pub fn start_offset(&self) -> usize {
7054        self.offset
7055    }
7056
7057    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7058    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7059        self.map_range_to_buffer(offset..offset).start
7060    }
7061
7062    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7063    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7064        self.diff_transforms
7065            .seek(&OutputDimension(range.start), Bias::Right);
7066        let start = self.map_offset_to_buffer_internal(range.start);
7067        let end = if range.end > range.start {
7068            self.diff_transforms
7069                .seek_forward(&OutputDimension(range.end), Bias::Right);
7070            self.map_offset_to_buffer_internal(range.end)
7071        } else {
7072            start
7073        };
7074        start..end
7075    }
7076
7077    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7078        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7079        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7080            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7081        };
7082        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7083        self.buffer_offset + offset_in_excerpt
7084    }
7085
7086    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7087    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7088        self.map_range_from_buffer(buffer_offset..buffer_offset)
7089            .start
7090    }
7091
7092    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7093    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7094        if buffer_range.start < self.buffer_offset {
7095            log::warn!(
7096                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7097            );
7098            return buffer_range;
7099        }
7100        let overshoot = buffer_range.start - self.buffer_offset;
7101        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7102        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7103        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7104            log::warn!(
7105                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7106            );
7107            return buffer_range;
7108        }
7109        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7110        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7111
7112        let end = if buffer_range.end > buffer_range.start {
7113            let overshoot = buffer_range.end - self.buffer_offset;
7114            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7115            self.diff_transforms
7116                .seek_forward(&excerpt_offset, Bias::Right);
7117            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7118            self.diff_transforms.start().output_dimension.0 + overshoot
7119        } else {
7120            start
7121        };
7122
7123        start..end
7124    }
7125
7126    /// Returns true if the entirety of the given range is in the buffer's excerpt
7127    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7128        range.start >= self.excerpt.buffer_start_offset()
7129            && range.end <= self.excerpt.buffer_end_offset()
7130    }
7131
7132    pub fn max_buffer_row(&self) -> u32 {
7133        self.excerpt.max_buffer_row
7134    }
7135}
7136
7137impl ExcerptId {
7138    pub fn min() -> Self {
7139        Self(0)
7140    }
7141
7142    pub fn max() -> Self {
7143        Self(usize::MAX)
7144    }
7145
7146    pub fn to_proto(self) -> u64 {
7147        self.0 as _
7148    }
7149
7150    pub fn from_proto(proto: u64) -> Self {
7151        Self(proto as _)
7152    }
7153
7154    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7155        let a = snapshot.excerpt_locator_for_id(*self);
7156        let b = snapshot.excerpt_locator_for_id(*other);
7157        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7158    }
7159}
7160
7161impl From<ExcerptId> for usize {
7162    fn from(val: ExcerptId) -> Self {
7163        val.0
7164    }
7165}
7166
7167impl fmt::Debug for Excerpt {
7168    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7169        f.debug_struct("Excerpt")
7170            .field("id", &self.id)
7171            .field("locator", &self.locator)
7172            .field("buffer_id", &self.buffer_id)
7173            .field("range", &self.range)
7174            .field("text_summary", &self.text_summary)
7175            .field("has_trailing_newline", &self.has_trailing_newline)
7176            .finish()
7177    }
7178}
7179
7180impl sum_tree::Item for Excerpt {
7181    type Summary = ExcerptSummary;
7182
7183    fn summary(&self, _cx: &()) -> Self::Summary {
7184        let mut text = self.text_summary;
7185        if self.has_trailing_newline {
7186            text += TextSummary::from("\n");
7187        }
7188        ExcerptSummary {
7189            excerpt_id: self.id,
7190            excerpt_locator: self.locator.clone(),
7191            widest_line_number: self.max_buffer_row,
7192            text,
7193        }
7194    }
7195}
7196
7197impl sum_tree::Item for ExcerptIdMapping {
7198    type Summary = ExcerptId;
7199
7200    fn summary(&self, _cx: &()) -> Self::Summary {
7201        self.id
7202    }
7203}
7204
7205impl sum_tree::KeyedItem for ExcerptIdMapping {
7206    type Key = ExcerptId;
7207
7208    fn key(&self) -> Self::Key {
7209        self.id
7210    }
7211}
7212
7213impl DiffTransform {
7214    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7215        match self {
7216            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7217            DiffTransform::BufferContent {
7218                inserted_hunk_info, ..
7219            } => *inserted_hunk_info,
7220        }
7221    }
7222}
7223
7224impl sum_tree::Item for DiffTransform {
7225    type Summary = DiffTransformSummary;
7226
7227    fn summary(&self, _: &<Self::Summary as sum_tree::Summary>::Context) -> Self::Summary {
7228        match self {
7229            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7230                input: *summary,
7231                output: *summary,
7232            },
7233            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7234                input: TextSummary::default(),
7235                output: *summary,
7236            },
7237        }
7238    }
7239}
7240
7241impl DiffTransformSummary {
7242    fn excerpt_len(&self) -> ExcerptOffset {
7243        ExcerptOffset::new(self.input.len)
7244    }
7245}
7246
7247impl sum_tree::Summary for DiffTransformSummary {
7248    type Context = ();
7249
7250    fn zero(_: &Self::Context) -> Self {
7251        DiffTransformSummary {
7252            input: TextSummary::default(),
7253            output: TextSummary::default(),
7254        }
7255    }
7256
7257    fn add_summary(&mut self, summary: &Self, _: &Self::Context) {
7258        self.input += &summary.input;
7259        self.output += &summary.output;
7260    }
7261}
7262
7263impl sum_tree::Summary for ExcerptId {
7264    type Context = ();
7265
7266    fn zero(_cx: &()) -> Self {
7267        Default::default()
7268    }
7269
7270    fn add_summary(&mut self, other: &Self, _: &()) {
7271        *self = *other;
7272    }
7273}
7274
7275impl sum_tree::Summary for ExcerptSummary {
7276    type Context = ();
7277
7278    fn zero(_cx: &()) -> Self {
7279        Default::default()
7280    }
7281
7282    fn add_summary(&mut self, summary: &Self, _: &()) {
7283        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7284        self.excerpt_locator = summary.excerpt_locator.clone();
7285        Summary::add_summary(&mut self.text, &summary.text, &());
7286        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7287    }
7288}
7289
7290impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7291    fn zero(_cx: &()) -> Self {
7292        Default::default()
7293    }
7294
7295    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
7296        self.value += summary.text.len;
7297    }
7298}
7299
7300impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7301    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
7302        Ord::cmp(&self.value, &cursor_location.text.len)
7303    }
7304}
7305
7306impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7307    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
7308        Ord::cmp(&Some(self), cursor_location)
7309    }
7310}
7311
7312impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7313    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
7314        Ord::cmp(self, &cursor_location.excerpt_locator)
7315    }
7316}
7317
7318impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7319    fn zero(_cx: &()) -> Self {
7320        Default::default()
7321    }
7322
7323    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
7324        self.value += summary.text.lines;
7325    }
7326}
7327
7328impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7329    for ExcerptDimension<D>
7330{
7331    fn zero(_: &()) -> Self {
7332        ExcerptDimension(D::default())
7333    }
7334
7335    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
7336        self.0.add_assign(&D::from_text_summary(&summary.text))
7337    }
7338}
7339
7340impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7341    fn zero(_cx: &()) -> Self {
7342        Default::default()
7343    }
7344
7345    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
7346        *self = Some(&summary.excerpt_locator);
7347    }
7348}
7349
7350impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7351    fn zero(_cx: &()) -> Self {
7352        Default::default()
7353    }
7354
7355    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
7356        *self = Some(summary.excerpt_id);
7357    }
7358}
7359
7360#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7361struct ExcerptDimension<T>(T);
7362
7363#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7364struct OutputDimension<T>(T);
7365
7366impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7367    fn zero(_: &()) -> Self {
7368        ExcerptOffset::new(0)
7369    }
7370
7371    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7372        self.value += summary.input.len;
7373    }
7374}
7375
7376impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7377    fn zero(_: &()) -> Self {
7378        ExcerptPoint::new(0, 0)
7379    }
7380
7381    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7382        self.value += summary.input.lines;
7383    }
7384}
7385
7386impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7387    for ExcerptDimension<D>
7388{
7389    fn cmp(&self, cursor_location: &DiffTransformSummary, _: &()) -> cmp::Ordering {
7390        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7391    }
7392}
7393
7394impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7395    for ExcerptDimension<D>
7396{
7397    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: &()) -> cmp::Ordering {
7398        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7399    }
7400}
7401
7402impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7403    fn zero(_: &()) -> Self {
7404        ExcerptDimension(D::default())
7405    }
7406
7407    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7408        self.0.add_assign(&D::from_text_summary(&summary.input))
7409    }
7410}
7411
7412impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7413    for OutputDimension<D>
7414{
7415    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: &()) -> cmp::Ordering {
7416        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7417    }
7418}
7419
7420impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7421    fn zero(_: &()) -> Self {
7422        OutputDimension(D::default())
7423    }
7424
7425    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7426        self.0.add_assign(&D::from_text_summary(&summary.output))
7427    }
7428}
7429
7430impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7431    fn zero(_: &()) -> Self {
7432        TextSummary::default()
7433    }
7434
7435    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7436        *self += summary.output
7437    }
7438}
7439
7440impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7441    fn zero(_: &()) -> Self {
7442        0
7443    }
7444
7445    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7446        *self += summary.output.len
7447    }
7448}
7449
7450impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7451    fn zero(_: &()) -> Self {
7452        Point::new(0, 0)
7453    }
7454
7455    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
7456        *self += summary.output.lines
7457    }
7458}
7459
7460impl MultiBufferRows<'_> {
7461    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7462        self.point = Point::new(row, 0);
7463        self.cursor.seek(&self.point);
7464    }
7465}
7466
7467impl Iterator for MultiBufferRows<'_> {
7468    type Item = RowInfo;
7469
7470    fn next(&mut self) -> Option<Self::Item> {
7471        if self.is_empty && self.point.row == 0 {
7472            self.point += Point::new(1, 0);
7473            return Some(RowInfo {
7474                buffer_id: None,
7475                buffer_row: Some(0),
7476                multibuffer_row: Some(MultiBufferRow(0)),
7477                diff_status: None,
7478                expand_info: None,
7479            });
7480        }
7481
7482        let mut region = self.cursor.region()?;
7483        while self.point >= region.range.end {
7484            self.cursor.next();
7485            if let Some(next_region) = self.cursor.region() {
7486                region = next_region;
7487            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7488                let multibuffer_row = MultiBufferRow(self.point.row);
7489                let last_excerpt = self
7490                    .cursor
7491                    .excerpts
7492                    .item()
7493                    .or(self.cursor.excerpts.prev_item())?;
7494                let last_row = last_excerpt
7495                    .range
7496                    .context
7497                    .end
7498                    .to_point(&last_excerpt.buffer)
7499                    .row;
7500
7501                let first_row = last_excerpt
7502                    .range
7503                    .context
7504                    .start
7505                    .to_point(&last_excerpt.buffer)
7506                    .row;
7507
7508                let expand_info = if self.is_singleton {
7509                    None
7510                } else {
7511                    let needs_expand_up = first_row == last_row
7512                        && last_row > 0
7513                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7514                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
7515
7516                    if needs_expand_up && needs_expand_down {
7517                        Some(ExpandExcerptDirection::UpAndDown)
7518                    } else if needs_expand_up {
7519                        Some(ExpandExcerptDirection::Up)
7520                    } else if needs_expand_down {
7521                        Some(ExpandExcerptDirection::Down)
7522                    } else {
7523                        None
7524                    }
7525                    .map(|direction| ExpandInfo {
7526                        direction,
7527                        excerpt_id: last_excerpt.id,
7528                    })
7529                };
7530                self.point += Point::new(1, 0);
7531                return Some(RowInfo {
7532                    buffer_id: Some(last_excerpt.buffer_id),
7533                    buffer_row: Some(last_row),
7534                    multibuffer_row: Some(multibuffer_row),
7535                    diff_status: None,
7536                    expand_info,
7537                });
7538            } else {
7539                return None;
7540            };
7541        }
7542
7543        let overshoot = self.point - region.range.start;
7544        let buffer_point = region.buffer_range.start + overshoot;
7545        let expand_info = if self.is_singleton {
7546            None
7547        } else {
7548            let needs_expand_up = self.point.row == region.range.start.row
7549                && self.cursor.is_at_start_of_excerpt()
7550                && buffer_point.row > 0;
7551            let needs_expand_down = (region.excerpt.has_trailing_newline
7552                && self.point.row + 1 == region.range.end.row
7553                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7554                && self.cursor.is_at_end_of_excerpt()
7555                && buffer_point.row < region.buffer.max_point().row;
7556
7557            if needs_expand_up && needs_expand_down {
7558                Some(ExpandExcerptDirection::UpAndDown)
7559            } else if needs_expand_up {
7560                Some(ExpandExcerptDirection::Up)
7561            } else if needs_expand_down {
7562                Some(ExpandExcerptDirection::Down)
7563            } else {
7564                None
7565            }
7566            .map(|direction| ExpandInfo {
7567                direction,
7568                excerpt_id: region.excerpt.id,
7569            })
7570        };
7571
7572        let result = Some(RowInfo {
7573            buffer_id: Some(region.buffer.remote_id()),
7574            buffer_row: Some(buffer_point.row),
7575            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7576            diff_status: region
7577                .diff_hunk_status
7578                .filter(|_| self.point < region.range.end),
7579            expand_info,
7580        });
7581        self.point += Point::new(1, 0);
7582        result
7583    }
7584}
7585
7586impl<'a> MultiBufferChunks<'a> {
7587    pub fn offset(&self) -> usize {
7588        self.range.start
7589    }
7590
7591    pub fn seek(&mut self, range: Range<usize>) {
7592        self.diff_transforms.seek(&range.end, Bias::Right);
7593        let mut excerpt_end = self.diff_transforms.start().1;
7594        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7595            let overshoot = range.end - self.diff_transforms.start().0;
7596            excerpt_end.value += overshoot;
7597        }
7598
7599        self.diff_transforms.seek(&range.start, Bias::Right);
7600        let mut excerpt_start = self.diff_transforms.start().1;
7601        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7602            let overshoot = range.start - self.diff_transforms.start().0;
7603            excerpt_start.value += overshoot;
7604        }
7605
7606        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7607        self.buffer_chunk.take();
7608        self.range = range;
7609    }
7610
7611    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7612        self.excerpt_offset_range = new_range.clone();
7613        self.excerpts.seek(&new_range.start, Bias::Right);
7614        if let Some(excerpt) = self.excerpts.item() {
7615            let excerpt_start = *self.excerpts.start();
7616            if let Some(excerpt_chunks) = self
7617                .excerpt_chunks
7618                .as_mut()
7619                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7620            {
7621                excerpt.seek_chunks(
7622                    excerpt_chunks,
7623                    (self.excerpt_offset_range.start - excerpt_start).value
7624                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7625                );
7626            } else {
7627                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7628                    (self.excerpt_offset_range.start - excerpt_start).value
7629                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7630                    self.language_aware,
7631                ));
7632            }
7633        } else {
7634            self.excerpt_chunks = None;
7635        }
7636    }
7637
7638    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7639        loop {
7640            if self.excerpt_offset_range.is_empty() {
7641                return None;
7642            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7643                self.excerpt_offset_range.start.value += chunk.text.len();
7644                return Some(chunk);
7645            } else {
7646                self.excerpts.next();
7647                let excerpt = self.excerpts.item()?;
7648                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7649                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7650                    self.language_aware,
7651                ));
7652            }
7653        }
7654    }
7655}
7656
7657impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7658    type Item = &'a str;
7659
7660    fn next(&mut self) -> Option<Self::Item> {
7661        let mut region = self.cursor.region()?;
7662        if self.offset == region.range.start {
7663            self.cursor.prev();
7664            region = self.cursor.region()?;
7665            let start_overshoot = self.start.saturating_sub(region.range.start);
7666            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7667                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7668            ));
7669        }
7670
7671        if self.offset == region.range.end && region.has_trailing_newline {
7672            self.offset -= 1;
7673            Some("\n")
7674        } else {
7675            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7676            self.offset -= chunk.len();
7677            Some(chunk)
7678        }
7679    }
7680}
7681
7682impl<'a> Iterator for MultiBufferChunks<'a> {
7683    type Item = Chunk<'a>;
7684
7685    fn next(&mut self) -> Option<Chunk<'a>> {
7686        if self.range.start >= self.range.end {
7687            return None;
7688        }
7689        if self.range.start == self.diff_transforms.end().0 {
7690            self.diff_transforms.next();
7691        }
7692
7693        let diff_transform_start = self.diff_transforms.start().0;
7694        let diff_transform_end = self.diff_transforms.end().0;
7695        debug_assert!(self.range.start < diff_transform_end);
7696
7697        let diff_transform = self.diff_transforms.item()?;
7698        match diff_transform {
7699            DiffTransform::BufferContent { .. } => {
7700                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7701                    chunk
7702                } else {
7703                    let chunk = self.next_excerpt_chunk().unwrap();
7704                    self.buffer_chunk.insert(chunk)
7705                };
7706
7707                let chunk_end = self.range.start + chunk.text.len();
7708                let diff_transform_end = diff_transform_end.min(self.range.end);
7709
7710                if diff_transform_end < chunk_end {
7711                    let (before, after) =
7712                        chunk.text.split_at(diff_transform_end - self.range.start);
7713                    self.range.start = diff_transform_end;
7714                    chunk.text = after;
7715                    Some(Chunk {
7716                        text: before,
7717                        ..chunk.clone()
7718                    })
7719                } else {
7720                    self.range.start = chunk_end;
7721                    self.buffer_chunk.take()
7722                }
7723            }
7724            DiffTransform::DeletedHunk {
7725                buffer_id,
7726                base_text_byte_range,
7727                has_trailing_newline,
7728                ..
7729            } => {
7730                let base_text_start =
7731                    base_text_byte_range.start + self.range.start - diff_transform_start;
7732                let base_text_end =
7733                    base_text_byte_range.start + self.range.end - diff_transform_start;
7734                let base_text_end = base_text_end.min(base_text_byte_range.end);
7735
7736                let mut chunks = if let Some((_, mut chunks)) = self
7737                    .diff_base_chunks
7738                    .take()
7739                    .filter(|(id, _)| id == buffer_id)
7740                {
7741                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7742                    {
7743                        chunks.seek(base_text_start..base_text_end);
7744                    }
7745                    chunks
7746                } else {
7747                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7748                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7749                };
7750
7751                let chunk = if let Some(chunk) = chunks.next() {
7752                    self.range.start += chunk.text.len();
7753                    self.diff_base_chunks = Some((*buffer_id, chunks));
7754                    chunk
7755                } else {
7756                    debug_assert!(has_trailing_newline);
7757                    self.range.start += "\n".len();
7758                    Chunk {
7759                        text: "\n",
7760                        ..Default::default()
7761                    }
7762                };
7763                Some(chunk)
7764            }
7765        }
7766    }
7767}
7768
7769impl MultiBufferBytes<'_> {
7770    fn consume(&mut self, len: usize) {
7771        self.range.start += len;
7772        self.chunk = &self.chunk[len..];
7773
7774        if !self.range.is_empty() && self.chunk.is_empty() {
7775            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7776                self.chunk = chunk;
7777            } else if self.has_trailing_newline {
7778                self.has_trailing_newline = false;
7779                self.chunk = b"\n";
7780            } else {
7781                self.cursor.next();
7782                if let Some(region) = self.cursor.region() {
7783                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7784                        region.buffer_range.start
7785                            ..(region.buffer_range.start + self.range.end - region.range.start)
7786                                .min(region.buffer_range.end),
7787                    );
7788                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7789                    self.excerpt_bytes = Some(excerpt_bytes);
7790                    self.has_trailing_newline =
7791                        region.has_trailing_newline && self.range.end >= region.range.end;
7792                    if self.chunk.is_empty() && self.has_trailing_newline {
7793                        self.has_trailing_newline = false;
7794                        self.chunk = b"\n";
7795                    }
7796                }
7797            }
7798        }
7799    }
7800}
7801
7802impl<'a> Iterator for MultiBufferBytes<'a> {
7803    type Item = &'a [u8];
7804
7805    fn next(&mut self) -> Option<Self::Item> {
7806        let chunk = self.chunk;
7807        if chunk.is_empty() {
7808            None
7809        } else {
7810            self.consume(chunk.len());
7811            Some(chunk)
7812        }
7813    }
7814}
7815
7816impl io::Read for MultiBufferBytes<'_> {
7817    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7818        let len = cmp::min(buf.len(), self.chunk.len());
7819        buf[..len].copy_from_slice(&self.chunk[..len]);
7820        if len > 0 {
7821            self.consume(len);
7822        }
7823        Ok(len)
7824    }
7825}
7826
7827impl io::Read for ReversedMultiBufferBytes<'_> {
7828    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7829        let len = cmp::min(buf.len(), self.chunk.len());
7830        buf[..len].copy_from_slice(&self.chunk[..len]);
7831        buf[..len].reverse();
7832        if len > 0 {
7833            self.range.end -= len;
7834            self.chunk = &self.chunk[..self.chunk.len() - len];
7835            if !self.range.is_empty()
7836                && self.chunk.is_empty()
7837                && let Some(chunk) = self.chunks.next()
7838            {
7839                self.chunk = chunk.as_bytes();
7840            }
7841        }
7842        Ok(len)
7843    }
7844}
7845
7846impl<'a> Iterator for ExcerptChunks<'a> {
7847    type Item = Chunk<'a>;
7848
7849    fn next(&mut self) -> Option<Self::Item> {
7850        if let Some(chunk) = self.content_chunks.next() {
7851            return Some(chunk);
7852        }
7853
7854        if self.footer_height > 0 {
7855            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7856            self.footer_height = 0;
7857            return Some(Chunk {
7858                text,
7859                ..Default::default()
7860            });
7861        }
7862
7863        None
7864    }
7865}
7866
7867impl ToOffset for Point {
7868    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7869        snapshot.point_to_offset(*self)
7870    }
7871}
7872
7873impl ToOffset for usize {
7874    #[track_caller]
7875    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7876        assert!(
7877            *self <= snapshot.len(),
7878            "offset {} is greater than the snapshot.len() {}",
7879            *self,
7880            snapshot.len(),
7881        );
7882        *self
7883    }
7884}
7885
7886impl ToOffset for OffsetUtf16 {
7887    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7888        snapshot.offset_utf16_to_offset(*self)
7889    }
7890}
7891
7892impl ToOffset for PointUtf16 {
7893    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7894        snapshot.point_utf16_to_offset(*self)
7895    }
7896}
7897
7898impl ToOffsetUtf16 for OffsetUtf16 {
7899    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7900        *self
7901    }
7902}
7903
7904impl ToOffsetUtf16 for usize {
7905    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7906        snapshot.offset_to_offset_utf16(*self)
7907    }
7908}
7909
7910impl ToPoint for usize {
7911    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7912        snapshot.offset_to_point(*self)
7913    }
7914}
7915
7916impl ToPoint for Point {
7917    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7918        *self
7919    }
7920}
7921
7922impl ToPointUtf16 for usize {
7923    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7924        snapshot.offset_to_point_utf16(*self)
7925    }
7926}
7927
7928impl ToPointUtf16 for Point {
7929    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7930        snapshot.point_to_point_utf16(*self)
7931    }
7932}
7933
7934impl ToPointUtf16 for PointUtf16 {
7935    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7936        *self
7937    }
7938}
7939
7940impl From<ExcerptId> for EntityId {
7941    fn from(id: ExcerptId) -> Self {
7942        EntityId::from(id.0 as u64)
7943    }
7944}