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, CharScopeContext, Chunk, CursorShape, DiagnosticEntryRef, DiskState, File,
  21    IndentGuideSettings, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16, Outline,
  22    OutlineItem, Point, PointUtf16, Selection, TextDimension, TextObject, ToOffset as _,
  23    ToPoint as _, TransactionId, TreeSitterOptions, Unclipped,
  24    language_settings::{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    rc::Rc,
  41    str,
  42    sync::Arc,
  43    time::{Duration, Instant},
  44};
  45use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, Summary, TreeMap};
  46use text::{
  47    BufferId, Edit, LineIndent, TextSummary,
  48    locator::Locator,
  49    subscription::{Subscription, Topic},
  50};
  51use theme::SyntaxTheme;
  52use util::{post_inc, rel_path::RelPath};
  53
  54const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  55
  56#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  57pub struct ExcerptId(u32);
  58
  59/// One or more [`Buffers`](Buffer) being edited in a single view.
  60///
  61/// See <https://zed.dev/features#multi-buffers>
  62pub struct MultiBuffer {
  63    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  64    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  65    snapshot: RefCell<MultiBufferSnapshot>,
  66    /// Contains the state of the buffers being edited
  67    buffers: RefCell<HashMap<BufferId, BufferState>>,
  68    // only used by consumers using `set_excerpts_for_buffer`
  69    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  70    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  71    diffs: HashMap<BufferId, DiffState>,
  72    // all_diff_hunks_expanded: bool,
  73    subscriptions: Topic,
  74    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  75    singleton: bool,
  76    history: History,
  77    title: Option<String>,
  78    capability: Capability,
  79    buffer_changed_since_sync: Rc<Cell<bool>>,
  80}
  81
  82#[derive(Clone, Debug, PartialEq, Eq)]
  83pub enum Event {
  84    ExcerptsAdded {
  85        buffer: Entity<Buffer>,
  86        predecessor: ExcerptId,
  87        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  88    },
  89    ExcerptsRemoved {
  90        ids: Vec<ExcerptId>,
  91        removed_buffer_ids: Vec<BufferId>,
  92    },
  93    ExcerptsExpanded {
  94        ids: Vec<ExcerptId>,
  95    },
  96    ExcerptsEdited {
  97        excerpt_ids: Vec<ExcerptId>,
  98        buffer_ids: Vec<BufferId>,
  99    },
 100    DiffHunksToggled,
 101    Edited {
 102        edited_buffer: Option<Entity<Buffer>>,
 103    },
 104    TransactionUndone {
 105        transaction_id: TransactionId,
 106    },
 107    Reloaded,
 108    LanguageChanged(BufferId),
 109    Reparsed(BufferId),
 110    Saved,
 111    FileHandleChanged,
 112    DirtyChanged,
 113    DiagnosticsUpdated,
 114    BufferDiffChanged,
 115}
 116
 117/// A diff hunk, representing a range of consequent lines in a multibuffer.
 118#[derive(Debug, Clone, PartialEq, Eq)]
 119pub struct MultiBufferDiffHunk {
 120    /// The row range in the multibuffer where this diff hunk appears.
 121    pub row_range: Range<MultiBufferRow>,
 122    /// The buffer ID that this hunk belongs to.
 123    pub buffer_id: BufferId,
 124    /// The range of the underlying buffer that this hunk corresponds to.
 125    pub buffer_range: Range<text::Anchor>,
 126    /// The excerpt that contains the diff hunk.
 127    pub excerpt_id: ExcerptId,
 128    /// The range within the buffer's diff base that this hunk corresponds to.
 129    pub diff_base_byte_range: Range<usize>,
 130    /// Whether or not this hunk also appears in the 'secondary diff'.
 131    pub secondary_status: DiffHunkSecondaryStatus,
 132}
 133
 134impl MultiBufferDiffHunk {
 135    pub fn status(&self) -> DiffHunkStatus {
 136        let kind = if self.buffer_range.start == self.buffer_range.end {
 137            DiffHunkStatusKind::Deleted
 138        } else if self.diff_base_byte_range.is_empty() {
 139            DiffHunkStatusKind::Added
 140        } else {
 141            DiffHunkStatusKind::Modified
 142        };
 143        DiffHunkStatus {
 144            kind,
 145            secondary: self.secondary_status,
 146        }
 147    }
 148
 149    pub fn is_created_file(&self) -> bool {
 150        self.diff_base_byte_range == (0..0)
 151            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 152    }
 153
 154    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 155        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 156        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 157        start..end
 158    }
 159}
 160
 161#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 162pub struct PathKey {
 163    // Used by the derived PartialOrd & Ord
 164    sort_prefix: Option<u64>,
 165    path: Arc<RelPath>,
 166}
 167
 168impl PathKey {
 169    pub fn with_sort_prefix(sort_prefix: u64, path: Arc<RelPath>) -> Self {
 170        Self {
 171            sort_prefix: Some(sort_prefix),
 172            path,
 173        }
 174    }
 175
 176    pub fn for_buffer(buffer: &Entity<Buffer>, cx: &App) -> Self {
 177        if let Some(file) = buffer.read(cx).file() {
 178            Self::with_sort_prefix(file.worktree_id(cx).to_proto(), file.path().clone())
 179        } else {
 180            Self {
 181                sort_prefix: None,
 182                path: RelPath::unix(&buffer.entity_id().to_string())
 183                    .unwrap()
 184                    .into_arc(),
 185            }
 186        }
 187    }
 188
 189    #[cfg(any(test, feature = "test-support"))]
 190    pub fn path(&self) -> &Arc<RelPath> {
 191        &self.path
 192    }
 193}
 194
 195pub type MultiBufferPoint = Point;
 196type ExcerptOffset = TypedOffset<Excerpt>;
 197type ExcerptPoint = TypedPoint<Excerpt>;
 198
 199#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 200#[serde(transparent)]
 201pub struct MultiBufferRow(pub u32);
 202
 203impl MultiBufferRow {
 204    pub const MIN: Self = Self(0);
 205    pub const MAX: Self = Self(u32::MAX);
 206}
 207
 208impl std::ops::Add<usize> for MultiBufferRow {
 209    type Output = Self;
 210
 211    fn add(self, rhs: usize) -> Self::Output {
 212        MultiBufferRow(self.0 + rhs as u32)
 213    }
 214}
 215
 216#[derive(Clone)]
 217struct History {
 218    next_transaction_id: TransactionId,
 219    undo_stack: Vec<Transaction>,
 220    redo_stack: Vec<Transaction>,
 221    transaction_depth: usize,
 222    group_interval: Duration,
 223}
 224
 225#[derive(Clone)]
 226struct Transaction {
 227    id: TransactionId,
 228    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 229    first_edit_at: Instant,
 230    last_edit_at: Instant,
 231    suppress_grouping: bool,
 232}
 233
 234pub trait ToOffset: 'static + fmt::Debug {
 235    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 236}
 237
 238pub trait ToOffsetUtf16: 'static + fmt::Debug {
 239    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 240}
 241
 242pub trait ToPoint: 'static + fmt::Debug {
 243    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 244}
 245
 246pub trait ToPointUtf16: 'static + fmt::Debug {
 247    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 248}
 249
 250struct BufferState {
 251    buffer: Entity<Buffer>,
 252    last_version: clock::Global,
 253    last_non_text_state_update_count: usize,
 254    excerpts: Vec<Locator>,
 255    _subscriptions: [gpui::Subscription; 2],
 256}
 257
 258struct DiffState {
 259    diff: Entity<BufferDiff>,
 260    _subscription: gpui::Subscription,
 261}
 262
 263impl DiffState {
 264    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 265        DiffState {
 266            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 267                BufferDiffEvent::DiffChanged { changed_range } => {
 268                    if let Some(changed_range) = changed_range.clone() {
 269                        this.buffer_diff_changed(diff, changed_range, cx)
 270                    }
 271                    cx.emit(Event::BufferDiffChanged);
 272                }
 273                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 274                _ => {}
 275            }),
 276            diff,
 277        }
 278    }
 279}
 280
 281/// The contents of a [`MultiBuffer`] at a single point in time.
 282#[derive(Clone, Default)]
 283pub struct MultiBufferSnapshot {
 284    singleton: bool,
 285    excerpts: SumTree<Excerpt>,
 286    excerpt_ids: SumTree<ExcerptIdMapping>,
 287    diffs: TreeMap<BufferId, BufferDiffSnapshot>,
 288    diff_transforms: SumTree<DiffTransform>,
 289    replaced_excerpts: TreeMap<ExcerptId, ExcerptId>,
 290    trailing_excerpt_update_count: usize,
 291    all_diff_hunks_expanded: bool,
 292    non_text_state_update_count: usize,
 293    edit_count: usize,
 294    is_dirty: bool,
 295    has_deleted_file: bool,
 296    has_conflict: bool,
 297    show_headers: bool,
 298}
 299
 300#[derive(Debug, Clone)]
 301enum DiffTransform {
 302    BufferContent {
 303        summary: TextSummary,
 304        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 305    },
 306    DeletedHunk {
 307        summary: TextSummary,
 308        buffer_id: BufferId,
 309        hunk_info: DiffTransformHunkInfo,
 310        base_text_byte_range: Range<usize>,
 311        has_trailing_newline: bool,
 312    },
 313}
 314
 315#[derive(Clone, Copy, Debug)]
 316struct DiffTransformHunkInfo {
 317    excerpt_id: ExcerptId,
 318    hunk_start_anchor: text::Anchor,
 319    hunk_secondary_status: DiffHunkSecondaryStatus,
 320}
 321
 322impl Eq for DiffTransformHunkInfo {}
 323
 324impl PartialEq for DiffTransformHunkInfo {
 325    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 326        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 327    }
 328}
 329
 330impl std::hash::Hash for DiffTransformHunkInfo {
 331    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 332        self.excerpt_id.hash(state);
 333        self.hunk_start_anchor.hash(state);
 334    }
 335}
 336
 337#[derive(Clone)]
 338pub struct ExcerptInfo {
 339    pub id: ExcerptId,
 340    pub buffer: BufferSnapshot,
 341    pub buffer_id: BufferId,
 342    pub range: ExcerptRange<text::Anchor>,
 343    pub end_row: MultiBufferRow,
 344}
 345
 346impl std::fmt::Debug for ExcerptInfo {
 347    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 348        f.debug_struct(type_name::<Self>())
 349            .field("id", &self.id)
 350            .field("buffer_id", &self.buffer_id)
 351            .field("path", &self.buffer.file().map(|f| f.path()))
 352            .field("range", &self.range)
 353            .finish()
 354    }
 355}
 356
 357/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 358#[derive(Debug)]
 359pub struct ExcerptBoundary {
 360    pub prev: Option<ExcerptInfo>,
 361    pub next: ExcerptInfo,
 362    /// The row in the `MultiBuffer` where the boundary is located
 363    pub row: MultiBufferRow,
 364}
 365
 366impl ExcerptBoundary {
 367    pub fn starts_new_buffer(&self) -> bool {
 368        match (self.prev.as_ref(), &self.next) {
 369            (None, _) => true,
 370            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 371        }
 372    }
 373}
 374
 375#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 376pub struct ExpandInfo {
 377    pub direction: ExpandExcerptDirection,
 378    pub excerpt_id: ExcerptId,
 379}
 380
 381#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 382pub struct RowInfo {
 383    pub buffer_id: Option<BufferId>,
 384    pub buffer_row: Option<u32>,
 385    pub multibuffer_row: Option<MultiBufferRow>,
 386    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 387    pub expand_info: Option<ExpandInfo>,
 388}
 389
 390/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 391#[derive(Clone)]
 392struct Excerpt {
 393    /// The unique identifier for this excerpt
 394    id: ExcerptId,
 395    /// The location of the excerpt in the [`MultiBuffer`]
 396    locator: Locator,
 397    /// The buffer being excerpted
 398    buffer_id: BufferId,
 399    /// A snapshot of the buffer being excerpted
 400    buffer: BufferSnapshot,
 401    /// The range of the buffer to be shown in the excerpt
 402    range: ExcerptRange<text::Anchor>,
 403    /// The last row in the excerpted slice of the buffer
 404    max_buffer_row: BufferRow,
 405    /// A summary of the text in the excerpt
 406    text_summary: TextSummary,
 407    has_trailing_newline: bool,
 408}
 409
 410/// A public view into an `Excerpt` in a [`MultiBuffer`].
 411///
 412/// Contains methods for getting the [`Buffer`] of the excerpt,
 413/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 414#[derive(Clone)]
 415pub struct MultiBufferExcerpt<'a> {
 416    excerpt: &'a Excerpt,
 417    diff_transforms: sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<usize>>,
 418    offset: usize,
 419    excerpt_offset: ExcerptDimension<usize>,
 420    buffer_offset: usize,
 421}
 422
 423#[derive(Clone, Debug)]
 424struct ExcerptIdMapping {
 425    id: ExcerptId,
 426    locator: Locator,
 427}
 428
 429/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 430/// These ranges are relative to the buffer itself
 431#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 432pub struct ExcerptRange<T> {
 433    /// The full range of text to be shown in the excerpt.
 434    pub context: Range<T>,
 435    /// The primary range of text to be highlighted in the excerpt.
 436    /// In a multi-buffer search, this would be the text that matched the search
 437    pub primary: Range<T>,
 438}
 439
 440impl<T: Clone> ExcerptRange<T> {
 441    pub fn new(context: Range<T>) -> Self {
 442        Self {
 443            context: context.clone(),
 444            primary: context,
 445        }
 446    }
 447}
 448
 449#[derive(Clone, Debug, Default)]
 450pub struct ExcerptSummary {
 451    excerpt_id: ExcerptId,
 452    /// The location of the last [`Excerpt`] being summarized
 453    excerpt_locator: Locator,
 454    widest_line_number: u32,
 455    text: TextSummary,
 456}
 457
 458#[derive(Debug, Clone)]
 459pub struct DiffTransformSummary {
 460    input: TextSummary,
 461    output: TextSummary,
 462}
 463
 464#[derive(Clone)]
 465pub struct MultiBufferRows<'a> {
 466    point: Point,
 467    is_empty: bool,
 468    is_singleton: bool,
 469    cursor: MultiBufferCursor<'a, Point>,
 470}
 471
 472pub struct MultiBufferChunks<'a> {
 473    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 474    diff_transforms: Cursor<'a, 'static, DiffTransform, Dimensions<usize, ExcerptOffset>>,
 475    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 476    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 477    buffer_chunk: Option<Chunk<'a>>,
 478    range: Range<usize>,
 479    excerpt_offset_range: Range<ExcerptOffset>,
 480    excerpt_chunks: Option<ExcerptChunks<'a>>,
 481    language_aware: bool,
 482}
 483
 484pub struct ReversedMultiBufferChunks<'a> {
 485    cursor: MultiBufferCursor<'a, usize>,
 486    current_chunks: Option<rope::Chunks<'a>>,
 487    start: usize,
 488    offset: usize,
 489}
 490
 491pub struct MultiBufferBytes<'a> {
 492    range: Range<usize>,
 493    cursor: MultiBufferCursor<'a, usize>,
 494    excerpt_bytes: Option<text::Bytes<'a>>,
 495    has_trailing_newline: bool,
 496    chunk: &'a [u8],
 497}
 498
 499pub struct ReversedMultiBufferBytes<'a> {
 500    range: Range<usize>,
 501    chunks: ReversedMultiBufferChunks<'a>,
 502    chunk: &'a [u8],
 503}
 504
 505#[derive(Clone)]
 506struct DiffTransforms<D> {
 507    output_dimension: OutputDimension<D>,
 508    excerpt_dimension: ExcerptDimension<D>,
 509}
 510
 511impl<'a, D: TextDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<D> {
 512    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
 513        Self {
 514            output_dimension: OutputDimension::zero(cx),
 515            excerpt_dimension: <ExcerptDimension<D> as Dimension<'a, DiffTransformSummary>>::zero(
 516                cx,
 517            ),
 518        }
 519    }
 520
 521    fn add_summary(
 522        &mut self,
 523        summary: &'a DiffTransformSummary,
 524        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
 525    ) {
 526        self.output_dimension.add_summary(summary, cx);
 527        self.excerpt_dimension.add_summary(summary, cx);
 528    }
 529}
 530
 531#[derive(Clone)]
 532struct MultiBufferCursor<'a, D: TextDimension> {
 533    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<D>>,
 534    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<D>>,
 535    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 536    cached_region: Option<MultiBufferRegion<'a, D>>,
 537}
 538
 539#[derive(Clone)]
 540struct MultiBufferRegion<'a, D: TextDimension> {
 541    buffer: &'a BufferSnapshot,
 542    is_main_buffer: bool,
 543    diff_hunk_status: Option<DiffHunkStatus>,
 544    excerpt: &'a Excerpt,
 545    buffer_range: Range<D>,
 546    range: Range<D>,
 547    has_trailing_newline: bool,
 548}
 549
 550struct ExcerptChunks<'a> {
 551    excerpt_id: ExcerptId,
 552    content_chunks: BufferChunks<'a>,
 553    footer_height: usize,
 554}
 555
 556#[derive(Debug)]
 557struct BufferEdit {
 558    range: Range<usize>,
 559    new_text: Arc<str>,
 560    is_insertion: bool,
 561    original_indent_column: Option<u32>,
 562    excerpt_id: ExcerptId,
 563}
 564
 565#[derive(Clone, Copy, Debug, PartialEq)]
 566enum DiffChangeKind {
 567    BufferEdited,
 568    DiffUpdated { base_changed: bool },
 569    ExpandOrCollapseHunks { expand: bool },
 570}
 571
 572#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 573pub enum ExpandExcerptDirection {
 574    Up,
 575    Down,
 576    UpAndDown,
 577}
 578
 579impl ExpandExcerptDirection {
 580    pub fn should_expand_up(&self) -> bool {
 581        match self {
 582            ExpandExcerptDirection::Up => true,
 583            ExpandExcerptDirection::Down => false,
 584            ExpandExcerptDirection::UpAndDown => true,
 585        }
 586    }
 587
 588    pub fn should_expand_down(&self) -> bool {
 589        match self {
 590            ExpandExcerptDirection::Up => false,
 591            ExpandExcerptDirection::Down => true,
 592            ExpandExcerptDirection::UpAndDown => true,
 593        }
 594    }
 595}
 596
 597#[derive(Clone, Debug, PartialEq)]
 598pub struct IndentGuide {
 599    pub buffer_id: BufferId,
 600    pub start_row: MultiBufferRow,
 601    pub end_row: MultiBufferRow,
 602    pub depth: u32,
 603    pub tab_size: u32,
 604    pub settings: IndentGuideSettings,
 605}
 606
 607impl IndentGuide {
 608    pub fn indent_level(&self) -> u32 {
 609        self.depth * self.tab_size
 610    }
 611}
 612
 613impl MultiBuffer {
 614    pub fn new(capability: Capability) -> Self {
 615        Self {
 616            snapshot: RefCell::new(MultiBufferSnapshot {
 617                show_headers: true,
 618                ..MultiBufferSnapshot::default()
 619            }),
 620            buffers: RefCell::default(),
 621            diffs: HashMap::default(),
 622            subscriptions: Topic::default(),
 623            singleton: false,
 624            capability,
 625            title: None,
 626            excerpts_by_path: Default::default(),
 627            paths_by_excerpt: Default::default(),
 628            buffer_changed_since_sync: Default::default(),
 629            history: History {
 630                next_transaction_id: clock::Lamport::default(),
 631                undo_stack: Vec::new(),
 632                redo_stack: Vec::new(),
 633                transaction_depth: 0,
 634                group_interval: Duration::from_millis(300),
 635            },
 636        }
 637    }
 638
 639    pub fn without_headers(capability: Capability) -> Self {
 640        Self {
 641            snapshot: Default::default(),
 642            buffers: Default::default(),
 643            excerpts_by_path: Default::default(),
 644            paths_by_excerpt: Default::default(),
 645            diffs: HashMap::default(),
 646            subscriptions: Default::default(),
 647            singleton: false,
 648            capability,
 649            buffer_changed_since_sync: Default::default(),
 650            history: History {
 651                next_transaction_id: Default::default(),
 652                undo_stack: Default::default(),
 653                redo_stack: Default::default(),
 654                transaction_depth: 0,
 655                group_interval: Duration::from_millis(300),
 656            },
 657            title: Default::default(),
 658        }
 659    }
 660
 661    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
 662        let mut buffers = HashMap::default();
 663        let buffer_changed_since_sync = Rc::new(Cell::new(false));
 664        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 665            buffer_state.buffer.update(new_cx, |buffer, _| {
 666                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
 667            });
 668            buffers.insert(
 669                *buffer_id,
 670                BufferState {
 671                    buffer: buffer_state.buffer.clone(),
 672                    last_version: buffer_state.last_version.clone(),
 673                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 674                    excerpts: buffer_state.excerpts.clone(),
 675                    _subscriptions: [
 676                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 677                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 678                    ],
 679                },
 680            );
 681        }
 682        let mut diff_bases = HashMap::default();
 683        for (buffer_id, diff) in self.diffs.iter() {
 684            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
 685        }
 686        Self {
 687            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 688            buffers: RefCell::new(buffers),
 689            excerpts_by_path: Default::default(),
 690            paths_by_excerpt: Default::default(),
 691            diffs: diff_bases,
 692            subscriptions: Default::default(),
 693            singleton: self.singleton,
 694            capability: self.capability,
 695            history: self.history.clone(),
 696            title: self.title.clone(),
 697            buffer_changed_since_sync,
 698        }
 699    }
 700
 701    pub fn with_title(mut self, title: String) -> Self {
 702        self.title = Some(title);
 703        self
 704    }
 705
 706    pub fn read_only(&self) -> bool {
 707        self.capability == Capability::ReadOnly
 708    }
 709
 710    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
 711        let mut this = Self::new(buffer.read(cx).capability());
 712        this.singleton = true;
 713        this.push_excerpts(
 714            buffer,
 715            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
 716            cx,
 717        );
 718        this.snapshot.borrow_mut().singleton = true;
 719        this
 720    }
 721
 722    /// Returns an up-to-date snapshot of the MultiBuffer.
 723    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
 724        self.sync(cx);
 725        self.snapshot.borrow().clone()
 726    }
 727
 728    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
 729        self.sync(cx);
 730        self.snapshot.borrow()
 731    }
 732
 733    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
 734        if self.singleton {
 735            Some(
 736                self.buffers
 737                    .borrow()
 738                    .values()
 739                    .next()
 740                    .unwrap()
 741                    .buffer
 742                    .clone(),
 743            )
 744        } else {
 745            None
 746        }
 747    }
 748
 749    pub fn is_singleton(&self) -> bool {
 750        self.singleton
 751    }
 752
 753    pub fn subscribe(&mut self) -> Subscription {
 754        self.subscriptions.subscribe()
 755    }
 756
 757    pub fn is_dirty(&self, cx: &App) -> bool {
 758        self.read(cx).is_dirty()
 759    }
 760
 761    pub fn has_deleted_file(&self, cx: &App) -> bool {
 762        self.read(cx).has_deleted_file()
 763    }
 764
 765    pub fn has_conflict(&self, cx: &App) -> bool {
 766        self.read(cx).has_conflict()
 767    }
 768
 769    // The `is_empty` signature doesn't match what clippy expects
 770    #[allow(clippy::len_without_is_empty)]
 771    pub fn len(&self, cx: &App) -> usize {
 772        self.read(cx).len()
 773    }
 774
 775    pub fn is_empty(&self) -> bool {
 776        self.buffers.borrow().is_empty()
 777    }
 778
 779    pub fn symbols_containing<T: ToOffset>(
 780        &self,
 781        offset: T,
 782        theme: Option<&SyntaxTheme>,
 783        cx: &App,
 784    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 785        self.read(cx).symbols_containing(offset, theme)
 786    }
 787
 788    pub fn edit<I, S, T>(
 789        &self,
 790        edits: I,
 791        autoindent_mode: Option<AutoindentMode>,
 792        cx: &mut Context<Self>,
 793    ) where
 794        I: IntoIterator<Item = (Range<S>, T)>,
 795        S: ToOffset,
 796        T: Into<Arc<str>>,
 797    {
 798        let snapshot = self.read(cx);
 799        let edits = edits
 800            .into_iter()
 801            .map(|(range, new_text)| {
 802                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 803                if range.start > range.end {
 804                    mem::swap(&mut range.start, &mut range.end);
 805                }
 806                (range, new_text.into())
 807            })
 808            .collect::<Vec<_>>();
 809
 810        return edit_internal(self, snapshot, edits, autoindent_mode, cx);
 811
 812        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 813        fn edit_internal(
 814            this: &MultiBuffer,
 815            snapshot: Ref<MultiBufferSnapshot>,
 816            edits: Vec<(Range<usize>, Arc<str>)>,
 817            mut autoindent_mode: Option<AutoindentMode>,
 818            cx: &mut Context<MultiBuffer>,
 819        ) {
 820            if this.read_only() || this.buffers.borrow().is_empty() {
 821                return;
 822            }
 823
 824            let original_indent_columns = match &mut autoindent_mode {
 825                Some(AutoindentMode::Block {
 826                    original_indent_columns,
 827                }) => mem::take(original_indent_columns),
 828                _ => Default::default(),
 829            };
 830
 831            let (buffer_edits, edited_excerpt_ids) =
 832                this.convert_edits_to_buffer_edits(edits, &snapshot, &original_indent_columns);
 833            drop(snapshot);
 834
 835            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
 836            for (buffer_id, mut edits) in buffer_edits {
 837                buffer_ids.push(buffer_id);
 838                edits.sort_by_key(|edit| edit.range.start);
 839                this.buffers.borrow()[&buffer_id]
 840                    .buffer
 841                    .update(cx, |buffer, cx| {
 842                        let mut edits = edits.into_iter().peekable();
 843                        let mut insertions = Vec::new();
 844                        let mut original_indent_columns = Vec::new();
 845                        let mut deletions = Vec::new();
 846                        let empty_str: Arc<str> = Arc::default();
 847                        while let Some(BufferEdit {
 848                            mut range,
 849                            mut new_text,
 850                            mut is_insertion,
 851                            original_indent_column,
 852                            excerpt_id,
 853                        }) = edits.next()
 854                        {
 855                            while let Some(BufferEdit {
 856                                range: next_range,
 857                                is_insertion: next_is_insertion,
 858                                new_text: next_new_text,
 859                                excerpt_id: next_excerpt_id,
 860                                ..
 861                            }) = edits.peek()
 862                            {
 863                                if range.end >= next_range.start {
 864                                    range.end = cmp::max(next_range.end, range.end);
 865                                    is_insertion |= *next_is_insertion;
 866                                    if excerpt_id == *next_excerpt_id {
 867                                        new_text = format!("{new_text}{next_new_text}").into();
 868                                    }
 869                                    edits.next();
 870                                } else {
 871                                    break;
 872                                }
 873                            }
 874
 875                            if is_insertion {
 876                                original_indent_columns.push(original_indent_column);
 877                                insertions.push((
 878                                    buffer.anchor_before(range.start)
 879                                        ..buffer.anchor_before(range.end),
 880                                    new_text.clone(),
 881                                ));
 882                            } else if !range.is_empty() {
 883                                deletions.push((
 884                                    buffer.anchor_before(range.start)
 885                                        ..buffer.anchor_before(range.end),
 886                                    empty_str.clone(),
 887                                ));
 888                            }
 889                        }
 890
 891                        let deletion_autoindent_mode =
 892                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 893                                Some(AutoindentMode::Block {
 894                                    original_indent_columns: Default::default(),
 895                                })
 896                            } else {
 897                                autoindent_mode.clone()
 898                            };
 899                        let insertion_autoindent_mode =
 900                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 901                                Some(AutoindentMode::Block {
 902                                    original_indent_columns,
 903                                })
 904                            } else {
 905                                autoindent_mode.clone()
 906                            };
 907
 908                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 909                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 910                    })
 911            }
 912
 913            cx.emit(Event::ExcerptsEdited {
 914                excerpt_ids: edited_excerpt_ids,
 915                buffer_ids,
 916            });
 917        }
 918    }
 919
 920    fn convert_edits_to_buffer_edits(
 921        &self,
 922        edits: Vec<(Range<usize>, Arc<str>)>,
 923        snapshot: &MultiBufferSnapshot,
 924        original_indent_columns: &[Option<u32>],
 925    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
 926        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 927        let mut edited_excerpt_ids = Vec::new();
 928        let mut cursor = snapshot.cursor::<usize>();
 929        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
 930            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
 931
 932            cursor.seek(&range.start);
 933            let mut start_region = cursor.region().expect("start offset out of bounds");
 934            if !start_region.is_main_buffer {
 935                cursor.next();
 936                if let Some(region) = cursor.region() {
 937                    start_region = region;
 938                } else {
 939                    continue;
 940                }
 941            }
 942
 943            if range.end < start_region.range.start {
 944                continue;
 945            }
 946
 947            if range.end > start_region.range.end {
 948                cursor.seek_forward(&range.end);
 949            }
 950            let mut end_region = cursor.region().expect("end offset out of bounds");
 951            if !end_region.is_main_buffer {
 952                cursor.prev();
 953                if let Some(region) = cursor.region() {
 954                    end_region = region;
 955                } else {
 956                    continue;
 957                }
 958            }
 959
 960            if range.start > end_region.range.end {
 961                continue;
 962            }
 963
 964            let start_overshoot = range.start.saturating_sub(start_region.range.start);
 965            let end_overshoot = range.end.saturating_sub(end_region.range.start);
 966            let buffer_start = (start_region.buffer_range.start + start_overshoot)
 967                .min(start_region.buffer_range.end);
 968            let buffer_end =
 969                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
 970
 971            if start_region.excerpt.id == end_region.excerpt.id {
 972                if start_region.is_main_buffer {
 973                    edited_excerpt_ids.push(start_region.excerpt.id);
 974                    buffer_edits
 975                        .entry(start_region.buffer.remote_id())
 976                        .or_default()
 977                        .push(BufferEdit {
 978                            range: buffer_start..buffer_end,
 979                            new_text,
 980                            is_insertion: true,
 981                            original_indent_column,
 982                            excerpt_id: start_region.excerpt.id,
 983                        });
 984                }
 985            } else {
 986                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
 987                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
 988                if start_region.is_main_buffer {
 989                    edited_excerpt_ids.push(start_region.excerpt.id);
 990                    buffer_edits
 991                        .entry(start_region.buffer.remote_id())
 992                        .or_default()
 993                        .push(BufferEdit {
 994                            range: start_excerpt_range,
 995                            new_text: new_text.clone(),
 996                            is_insertion: true,
 997                            original_indent_column,
 998                            excerpt_id: start_region.excerpt.id,
 999                        });
1000                }
1001                if end_region.is_main_buffer {
1002                    edited_excerpt_ids.push(end_region.excerpt.id);
1003                    buffer_edits
1004                        .entry(end_region.buffer.remote_id())
1005                        .or_default()
1006                        .push(BufferEdit {
1007                            range: end_excerpt_range,
1008                            new_text: new_text.clone(),
1009                            is_insertion: false,
1010                            original_indent_column,
1011                            excerpt_id: end_region.excerpt.id,
1012                        });
1013                }
1014
1015                cursor.seek(&range.start);
1016                cursor.next_excerpt();
1017                while let Some(region) = cursor.region() {
1018                    if region.excerpt.id == end_region.excerpt.id {
1019                        break;
1020                    }
1021                    if region.is_main_buffer {
1022                        edited_excerpt_ids.push(region.excerpt.id);
1023                        buffer_edits
1024                            .entry(region.buffer.remote_id())
1025                            .or_default()
1026                            .push(BufferEdit {
1027                                range: region.buffer_range,
1028                                new_text: new_text.clone(),
1029                                is_insertion: false,
1030                                original_indent_column,
1031                                excerpt_id: region.excerpt.id,
1032                            });
1033                    }
1034                    cursor.next_excerpt();
1035                }
1036            }
1037        }
1038        (buffer_edits, edited_excerpt_ids)
1039    }
1040
1041    pub fn autoindent_ranges<I, S>(&self, ranges: I, cx: &mut Context<Self>)
1042    where
1043        I: IntoIterator<Item = Range<S>>,
1044        S: ToOffset,
1045    {
1046        let snapshot = self.read(cx);
1047        let empty = Arc::<str>::from("");
1048        let edits = ranges
1049            .into_iter()
1050            .map(|range| {
1051                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
1052                if range.start > range.end {
1053                    mem::swap(&mut range.start, &mut range.end);
1054                }
1055                (range, empty.clone())
1056            })
1057            .collect::<Vec<_>>();
1058
1059        return autoindent_ranges_internal(self, snapshot, edits, cx);
1060
1061        fn autoindent_ranges_internal(
1062            this: &MultiBuffer,
1063            snapshot: Ref<MultiBufferSnapshot>,
1064            edits: Vec<(Range<usize>, Arc<str>)>,
1065            cx: &mut Context<MultiBuffer>,
1066        ) {
1067            if this.read_only() || this.buffers.borrow().is_empty() {
1068                return;
1069            }
1070
1071            let (buffer_edits, edited_excerpt_ids) =
1072                this.convert_edits_to_buffer_edits(edits, &snapshot, &[]);
1073            drop(snapshot);
1074
1075            let mut buffer_ids = Vec::new();
1076            for (buffer_id, mut edits) in buffer_edits {
1077                buffer_ids.push(buffer_id);
1078                edits.sort_unstable_by_key(|edit| edit.range.start);
1079
1080                let mut ranges: Vec<Range<usize>> = Vec::new();
1081                for edit in edits {
1082                    if let Some(last_range) = ranges.last_mut()
1083                        && edit.range.start <= last_range.end
1084                    {
1085                        last_range.end = last_range.end.max(edit.range.end);
1086                        continue;
1087                    }
1088                    ranges.push(edit.range);
1089                }
1090
1091                this.buffers.borrow()[&buffer_id]
1092                    .buffer
1093                    .update(cx, |buffer, cx| {
1094                        buffer.autoindent_ranges(ranges, cx);
1095                    })
1096            }
1097
1098            cx.emit(Event::ExcerptsEdited {
1099                excerpt_ids: edited_excerpt_ids,
1100                buffer_ids,
1101            });
1102        }
1103    }
1104
1105    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
1106    // You can also request the insertion of empty lines above and below the line starting at the returned point.
1107    // Panics if the given position is invalid.
1108    pub fn insert_empty_line(
1109        &mut self,
1110        position: impl ToPoint,
1111        space_above: bool,
1112        space_below: bool,
1113        cx: &mut Context<Self>,
1114    ) -> Point {
1115        let multibuffer_point = position.to_point(&self.read(cx));
1116        let (buffer, buffer_point, _) = self.point_to_buffer_point(multibuffer_point, cx).unwrap();
1117        self.start_transaction(cx);
1118        let empty_line_start = buffer.update(cx, |buffer, cx| {
1119            buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
1120        });
1121        self.end_transaction(cx);
1122        multibuffer_point + (empty_line_start - buffer_point)
1123    }
1124
1125    pub fn start_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1126        self.start_transaction_at(Instant::now(), cx)
1127    }
1128
1129    pub fn start_transaction_at(
1130        &mut self,
1131        now: Instant,
1132        cx: &mut Context<Self>,
1133    ) -> Option<TransactionId> {
1134        if let Some(buffer) = self.as_singleton() {
1135            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1136        }
1137
1138        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1139            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1140        }
1141        self.history.start_transaction(now)
1142    }
1143
1144    pub fn last_transaction_id(&self, cx: &App) -> Option<TransactionId> {
1145        if let Some(buffer) = self.as_singleton() {
1146            buffer
1147                .read(cx)
1148                .peek_undo_stack()
1149                .map(|history_entry| history_entry.transaction_id())
1150        } else {
1151            let last_transaction = self.history.undo_stack.last()?;
1152            Some(last_transaction.id)
1153        }
1154    }
1155
1156    pub fn end_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1157        self.end_transaction_at(Instant::now(), cx)
1158    }
1159
1160    pub fn end_transaction_at(
1161        &mut self,
1162        now: Instant,
1163        cx: &mut Context<Self>,
1164    ) -> Option<TransactionId> {
1165        if let Some(buffer) = self.as_singleton() {
1166            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
1167        }
1168
1169        let mut buffer_transactions = HashMap::default();
1170        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1171            if let Some(transaction_id) =
1172                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
1173            {
1174                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
1175            }
1176        }
1177
1178        if self.history.end_transaction(now, buffer_transactions) {
1179            let transaction_id = self.history.group().unwrap();
1180            Some(transaction_id)
1181        } else {
1182            None
1183        }
1184    }
1185
1186    pub fn edited_ranges_for_transaction<D>(
1187        &self,
1188        transaction_id: TransactionId,
1189        cx: &App,
1190    ) -> Vec<Range<D>>
1191    where
1192        D: TextDimension + Ord + Sub<D, Output = D>,
1193    {
1194        let Some(transaction) = self.history.transaction(transaction_id) else {
1195            return Vec::new();
1196        };
1197
1198        let mut ranges = Vec::new();
1199        let snapshot = self.read(cx);
1200        let buffers = self.buffers.borrow();
1201        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(());
1202
1203        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
1204            let Some(buffer_state) = buffers.get(buffer_id) else {
1205                continue;
1206            };
1207
1208            let buffer = buffer_state.buffer.read(cx);
1209            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
1210                for excerpt_id in &buffer_state.excerpts {
1211                    cursor.seek(excerpt_id, Bias::Left);
1212                    if let Some(excerpt) = cursor.item()
1213                        && excerpt.locator == *excerpt_id
1214                    {
1215                        let excerpt_buffer_start = excerpt.range.context.start.summary::<D>(buffer);
1216                        let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
1217                        let excerpt_range = excerpt_buffer_start..excerpt_buffer_end;
1218                        if excerpt_range.contains(&range.start)
1219                            && excerpt_range.contains(&range.end)
1220                        {
1221                            let excerpt_start = D::from_text_summary(&cursor.start().text);
1222
1223                            let mut start = excerpt_start;
1224                            start.add_assign(&(range.start - excerpt_buffer_start));
1225                            let mut end = excerpt_start;
1226                            end.add_assign(&(range.end - excerpt_buffer_start));
1227
1228                            ranges.push(start..end);
1229                            break;
1230                        }
1231                    }
1232                }
1233            }
1234        }
1235
1236        ranges.sort_by_key(|range| range.start);
1237        ranges
1238    }
1239
1240    pub fn merge_transactions(
1241        &mut self,
1242        transaction: TransactionId,
1243        destination: TransactionId,
1244        cx: &mut Context<Self>,
1245    ) {
1246        if let Some(buffer) = self.as_singleton() {
1247            buffer.update(cx, |buffer, _| {
1248                buffer.merge_transactions(transaction, destination)
1249            });
1250        } else if let Some(transaction) = self.history.forget(transaction)
1251            && let Some(destination) = self.history.transaction_mut(destination)
1252        {
1253            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1254                if let Some(destination_buffer_transaction_id) =
1255                    destination.buffer_transactions.get(&buffer_id)
1256                {
1257                    if let Some(state) = self.buffers.borrow().get(&buffer_id) {
1258                        state.buffer.update(cx, |buffer, _| {
1259                            buffer.merge_transactions(
1260                                buffer_transaction_id,
1261                                *destination_buffer_transaction_id,
1262                            )
1263                        });
1264                    }
1265                } else {
1266                    destination
1267                        .buffer_transactions
1268                        .insert(buffer_id, buffer_transaction_id);
1269                }
1270            }
1271        }
1272    }
1273
1274    pub fn finalize_last_transaction(&mut self, cx: &mut Context<Self>) {
1275        self.history.finalize_last_transaction();
1276        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1277            buffer.update(cx, |buffer, _| {
1278                buffer.finalize_last_transaction();
1279            });
1280        }
1281    }
1282
1283    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &Context<Self>)
1284    where
1285        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
1286    {
1287        self.history
1288            .push_transaction(buffer_transactions, Instant::now(), cx);
1289        self.history.finalize_last_transaction();
1290    }
1291
1292    pub fn group_until_transaction(
1293        &mut self,
1294        transaction_id: TransactionId,
1295        cx: &mut Context<Self>,
1296    ) {
1297        if let Some(buffer) = self.as_singleton() {
1298            buffer.update(cx, |buffer, _| {
1299                buffer.group_until_transaction(transaction_id)
1300            });
1301        } else {
1302            self.history.group_until(transaction_id);
1303        }
1304    }
1305
1306    pub fn set_active_selections(
1307        &self,
1308        selections: &[Selection<Anchor>],
1309        line_mode: bool,
1310        cursor_shape: CursorShape,
1311        cx: &mut Context<Self>,
1312    ) {
1313        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1314            Default::default();
1315        let snapshot = self.read(cx);
1316        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1317        for selection in selections {
1318            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1319            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1320
1321            cursor.seek(&Some(start_locator), Bias::Left);
1322            while let Some(excerpt) = cursor.item()
1323                && excerpt.locator <= *end_locator
1324            {
1325                let mut start = excerpt.range.context.start;
1326                let mut end = excerpt.range.context.end;
1327                if excerpt.id == selection.start.excerpt_id {
1328                    start = selection.start.text_anchor;
1329                }
1330                if excerpt.id == selection.end.excerpt_id {
1331                    end = selection.end.text_anchor;
1332                }
1333                selections_by_buffer
1334                    .entry(excerpt.buffer_id)
1335                    .or_default()
1336                    .push(Selection {
1337                        id: selection.id,
1338                        start,
1339                        end,
1340                        reversed: selection.reversed,
1341                        goal: selection.goal,
1342                    });
1343
1344                cursor.next();
1345            }
1346        }
1347
1348        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1349            if !selections_by_buffer.contains_key(buffer_id) {
1350                buffer_state
1351                    .buffer
1352                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1353            }
1354        }
1355
1356        for (buffer_id, mut selections) in selections_by_buffer {
1357            self.buffers.borrow()[&buffer_id]
1358                .buffer
1359                .update(cx, |buffer, cx| {
1360                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1361                    let mut selections = selections.into_iter().peekable();
1362                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1363                        let mut selection = selections.next()?;
1364                        while let Some(next_selection) = selections.peek() {
1365                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1366                                let next_selection = selections.next().unwrap();
1367                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1368                                    selection.end = next_selection.end;
1369                                }
1370                            } else {
1371                                break;
1372                            }
1373                        }
1374                        Some(selection)
1375                    }));
1376                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1377                });
1378        }
1379    }
1380
1381    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1382        for buffer in self.buffers.borrow().values() {
1383            buffer
1384                .buffer
1385                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1386        }
1387    }
1388
1389    pub fn undo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1390        let mut transaction_id = None;
1391        if let Some(buffer) = self.as_singleton() {
1392            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1393        } else {
1394            while let Some(transaction) = self.history.pop_undo() {
1395                let mut undone = false;
1396                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1397                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1398                        undone |= buffer.update(cx, |buffer, cx| {
1399                            let undo_to = *buffer_transaction_id;
1400                            if let Some(entry) = buffer.peek_undo_stack() {
1401                                *buffer_transaction_id = entry.transaction_id();
1402                            }
1403                            buffer.undo_to_transaction(undo_to, cx)
1404                        });
1405                    }
1406                }
1407
1408                if undone {
1409                    transaction_id = Some(transaction.id);
1410                    break;
1411                }
1412            }
1413        }
1414
1415        if let Some(transaction_id) = transaction_id {
1416            cx.emit(Event::TransactionUndone { transaction_id });
1417        }
1418
1419        transaction_id
1420    }
1421
1422    pub fn redo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1423        if let Some(buffer) = self.as_singleton() {
1424            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1425        }
1426
1427        while let Some(transaction) = self.history.pop_redo() {
1428            let mut redone = false;
1429            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1430                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1431                    redone |= buffer.update(cx, |buffer, cx| {
1432                        let redo_to = *buffer_transaction_id;
1433                        if let Some(entry) = buffer.peek_redo_stack() {
1434                            *buffer_transaction_id = entry.transaction_id();
1435                        }
1436                        buffer.redo_to_transaction(redo_to, cx)
1437                    });
1438                }
1439            }
1440
1441            if redone {
1442                return Some(transaction.id);
1443            }
1444        }
1445
1446        None
1447    }
1448
1449    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1450        if let Some(buffer) = self.as_singleton() {
1451            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1452        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1453            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1454                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1455                    buffer.update(cx, |buffer, cx| {
1456                        buffer.undo_transaction(*transaction_id, cx)
1457                    });
1458                }
1459            }
1460        }
1461    }
1462
1463    pub fn forget_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1464        if let Some(buffer) = self.as_singleton() {
1465            buffer.update(cx, |buffer, _| {
1466                buffer.forget_transaction(transaction_id);
1467            });
1468        } else if let Some(transaction) = self.history.forget(transaction_id) {
1469            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1470                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1471                    state.buffer.update(cx, |buffer, _| {
1472                        buffer.forget_transaction(buffer_transaction_id);
1473                    });
1474                }
1475            }
1476        }
1477    }
1478
1479    pub fn push_excerpts<O>(
1480        &mut self,
1481        buffer: Entity<Buffer>,
1482        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1483        cx: &mut Context<Self>,
1484    ) -> Vec<ExcerptId>
1485    where
1486        O: text::ToOffset,
1487    {
1488        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1489    }
1490
1491    pub fn location_for_path(&self, path: &PathKey, cx: &App) -> Option<Anchor> {
1492        let excerpt_id = self.excerpts_by_path.get(path)?.first()?;
1493        let snapshot = self.snapshot(cx);
1494        let excerpt = snapshot.excerpt(*excerpt_id)?;
1495        Some(Anchor::in_buffer(
1496            *excerpt_id,
1497            excerpt.buffer_id,
1498            excerpt.range.context.start,
1499        ))
1500    }
1501
1502    pub fn excerpt_paths(&self) -> impl Iterator<Item = &PathKey> {
1503        self.excerpts_by_path.keys()
1504    }
1505
1506    fn expand_excerpts_with_paths(
1507        &mut self,
1508        ids: impl IntoIterator<Item = ExcerptId>,
1509        line_count: u32,
1510        direction: ExpandExcerptDirection,
1511        cx: &mut Context<Self>,
1512    ) {
1513        let grouped = ids
1514            .into_iter()
1515            .chunk_by(|id| self.paths_by_excerpt.get(id).cloned())
1516            .into_iter()
1517            .flat_map(|(k, v)| Some((k?, v.into_iter().collect::<Vec<_>>())))
1518            .collect::<Vec<_>>();
1519        let snapshot = self.snapshot(cx);
1520
1521        for (path, ids) in grouped.into_iter() {
1522            let Some(excerpt_ids) = self.excerpts_by_path.get(&path) else {
1523                continue;
1524            };
1525
1526            let ids_to_expand = HashSet::from_iter(ids);
1527            let expanded_ranges = excerpt_ids.iter().filter_map(|excerpt_id| {
1528                let excerpt = snapshot.excerpt(*excerpt_id)?;
1529
1530                let mut context = excerpt.range.context.to_point(&excerpt.buffer);
1531                if ids_to_expand.contains(excerpt_id) {
1532                    match direction {
1533                        ExpandExcerptDirection::Up => {
1534                            context.start.row = context.start.row.saturating_sub(line_count);
1535                            context.start.column = 0;
1536                        }
1537                        ExpandExcerptDirection::Down => {
1538                            context.end.row =
1539                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1540                            context.end.column = excerpt.buffer.line_len(context.end.row);
1541                        }
1542                        ExpandExcerptDirection::UpAndDown => {
1543                            context.start.row = context.start.row.saturating_sub(line_count);
1544                            context.start.column = 0;
1545                            context.end.row =
1546                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1547                            context.end.column = excerpt.buffer.line_len(context.end.row);
1548                        }
1549                    }
1550                }
1551
1552                Some(ExcerptRange {
1553                    context,
1554                    primary: excerpt.range.primary.to_point(&excerpt.buffer),
1555                })
1556            });
1557            let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1558            for range in expanded_ranges {
1559                if let Some(last_range) = merged_ranges.last_mut()
1560                    && last_range.context.end >= range.context.start
1561                {
1562                    last_range.context.end = range.context.end;
1563                    continue;
1564                }
1565                merged_ranges.push(range)
1566            }
1567            let Some(excerpt_id) = excerpt_ids.first() else {
1568                continue;
1569            };
1570            let Some(buffer_id) = &snapshot.buffer_id_for_excerpt(*excerpt_id) else {
1571                continue;
1572            };
1573
1574            let Some(buffer) = self
1575                .buffers
1576                .borrow()
1577                .get(buffer_id)
1578                .map(|b| b.buffer.clone())
1579            else {
1580                continue;
1581            };
1582
1583            let buffer_snapshot = buffer.read(cx).snapshot();
1584            self.update_path_excerpts(path.clone(), buffer, &buffer_snapshot, merged_ranges, cx);
1585        }
1586    }
1587
1588    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1589    pub fn set_excerpts_for_path(
1590        &mut self,
1591        path: PathKey,
1592        buffer: Entity<Buffer>,
1593        ranges: impl IntoIterator<Item = Range<Point>>,
1594        context_line_count: u32,
1595        cx: &mut Context<Self>,
1596    ) -> (Vec<Range<Anchor>>, bool) {
1597        let buffer_snapshot = buffer.read(cx).snapshot();
1598        let excerpt_ranges = build_excerpt_ranges(ranges, context_line_count, &buffer_snapshot);
1599
1600        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1601        self.set_merged_excerpt_ranges_for_path(
1602            path,
1603            buffer,
1604            excerpt_ranges,
1605            &buffer_snapshot,
1606            new,
1607            counts,
1608            cx,
1609        )
1610    }
1611
1612    pub fn set_excerpt_ranges_for_path(
1613        &mut self,
1614        path: PathKey,
1615        buffer: Entity<Buffer>,
1616        buffer_snapshot: &BufferSnapshot,
1617        excerpt_ranges: Vec<ExcerptRange<Point>>,
1618        cx: &mut Context<Self>,
1619    ) -> (Vec<Range<Anchor>>, bool) {
1620        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1621        self.set_merged_excerpt_ranges_for_path(
1622            path,
1623            buffer,
1624            excerpt_ranges,
1625            buffer_snapshot,
1626            new,
1627            counts,
1628            cx,
1629        )
1630    }
1631
1632    pub fn set_anchored_excerpts_for_path(
1633        &self,
1634        buffer: Entity<Buffer>,
1635        ranges: Vec<Range<text::Anchor>>,
1636        context_line_count: u32,
1637        cx: &mut Context<Self>,
1638    ) -> Task<Vec<Range<Anchor>>> {
1639        let buffer_snapshot = buffer.read(cx).snapshot();
1640        let path_key = PathKey::for_buffer(&buffer, cx);
1641        cx.spawn(async move |multi_buffer, cx| {
1642            let snapshot = buffer_snapshot.clone();
1643            let (excerpt_ranges, new, counts) = cx
1644                .background_spawn(async move {
1645                    let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
1646                    let excerpt_ranges =
1647                        build_excerpt_ranges(ranges, context_line_count, &snapshot);
1648                    let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1649                    (excerpt_ranges, new, counts)
1650                })
1651                .await;
1652
1653            multi_buffer
1654                .update(cx, move |multi_buffer, cx| {
1655                    let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
1656                        path_key,
1657                        buffer,
1658                        excerpt_ranges,
1659                        &buffer_snapshot,
1660                        new,
1661                        counts,
1662                        cx,
1663                    );
1664                    ranges
1665                })
1666                .ok()
1667                .unwrap_or_default()
1668        })
1669    }
1670
1671    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1672    fn set_merged_excerpt_ranges_for_path(
1673        &mut self,
1674        path: PathKey,
1675        buffer: Entity<Buffer>,
1676        ranges: Vec<ExcerptRange<Point>>,
1677        buffer_snapshot: &BufferSnapshot,
1678        new: Vec<ExcerptRange<Point>>,
1679        counts: Vec<usize>,
1680        cx: &mut Context<Self>,
1681    ) -> (Vec<Range<Anchor>>, bool) {
1682        let (excerpt_ids, added_a_new_excerpt) =
1683            self.update_path_excerpts(path, buffer, buffer_snapshot, new, cx);
1684
1685        let mut result = Vec::new();
1686        let mut ranges = ranges.into_iter();
1687        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(counts.into_iter()) {
1688            for range in ranges.by_ref().take(range_count) {
1689                let range = Anchor::range_in_buffer(
1690                    excerpt_id,
1691                    buffer_snapshot.remote_id(),
1692                    buffer_snapshot.anchor_before(&range.primary.start)
1693                        ..buffer_snapshot.anchor_after(&range.primary.end),
1694                );
1695                result.push(range)
1696            }
1697        }
1698        (result, added_a_new_excerpt)
1699    }
1700
1701    fn merge_excerpt_ranges<'a>(
1702        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1703    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1704        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1705        let mut counts: Vec<usize> = Vec::new();
1706        for range in expanded_ranges {
1707            if let Some(last_range) = merged_ranges.last_mut() {
1708                debug_assert!(
1709                    last_range.context.start <= range.context.start,
1710                    "Last range: {last_range:?} Range: {range:?}"
1711                );
1712                if last_range.context.end >= range.context.start
1713                    || last_range.context.end.row + 1 == range.context.start.row
1714                {
1715                    last_range.context.end = range.context.end.max(last_range.context.end);
1716                    *counts.last_mut().unwrap() += 1;
1717                    continue;
1718                }
1719            }
1720            merged_ranges.push(range.clone());
1721            counts.push(1);
1722        }
1723        (merged_ranges, counts)
1724    }
1725
1726    fn update_path_excerpts(
1727        &mut self,
1728        path: PathKey,
1729        buffer: Entity<Buffer>,
1730        buffer_snapshot: &BufferSnapshot,
1731        new: Vec<ExcerptRange<Point>>,
1732        cx: &mut Context<Self>,
1733    ) -> (Vec<ExcerptId>, bool) {
1734        let mut insert_after = self
1735            .excerpts_by_path
1736            .range(..path.clone())
1737            .next_back()
1738            .map(|(_, value)| *value.last().unwrap())
1739            .unwrap_or(ExcerptId::min());
1740
1741        let existing = self
1742            .excerpts_by_path
1743            .get(&path)
1744            .cloned()
1745            .unwrap_or_default();
1746
1747        let mut new_iter = new.into_iter().peekable();
1748        let mut existing_iter = existing.into_iter().peekable();
1749
1750        let mut excerpt_ids = Vec::new();
1751        let mut to_remove = Vec::new();
1752        let mut to_insert: Vec<(ExcerptId, ExcerptRange<Point>)> = Vec::new();
1753        let mut added_a_new_excerpt = false;
1754        let snapshot = self.snapshot(cx);
1755
1756        let mut next_excerpt_id =
1757            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1758                last_entry.id.0 + 1
1759            } else {
1760                1
1761            };
1762
1763        let mut next_excerpt_id = move || ExcerptId(post_inc(&mut next_excerpt_id));
1764
1765        let mut excerpts_cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1766        excerpts_cursor.next();
1767
1768        loop {
1769            let new = new_iter.peek();
1770            let existing = if let Some(existing_id) = existing_iter.peek() {
1771                let locator = snapshot.excerpt_locator_for_id(*existing_id);
1772                excerpts_cursor.seek_forward(&Some(locator), Bias::Left);
1773                if let Some(excerpt) = excerpts_cursor.item() {
1774                    if excerpt.buffer_id != buffer_snapshot.remote_id() {
1775                        to_remove.push(*existing_id);
1776                        existing_iter.next();
1777                        continue;
1778                    }
1779                    Some((
1780                        *existing_id,
1781                        excerpt.range.context.to_point(buffer_snapshot),
1782                    ))
1783                } else {
1784                    None
1785                }
1786            } else {
1787                None
1788            };
1789
1790            if let Some((last_id, last)) = to_insert.last_mut() {
1791                if let Some(new) = new
1792                    && last.context.end >= new.context.start
1793                {
1794                    last.context.end = last.context.end.max(new.context.end);
1795                    excerpt_ids.push(*last_id);
1796                    new_iter.next();
1797                    continue;
1798                }
1799                if let Some((existing_id, existing_range)) = &existing
1800                    && last.context.end >= existing_range.start
1801                {
1802                    last.context.end = last.context.end.max(existing_range.end);
1803                    to_remove.push(*existing_id);
1804                    self.snapshot
1805                        .borrow_mut()
1806                        .replaced_excerpts
1807                        .insert(*existing_id, *last_id);
1808                    existing_iter.next();
1809                    continue;
1810                }
1811            }
1812
1813            match (new, existing) {
1814                (None, None) => break,
1815                (None, Some((existing_id, _))) => {
1816                    existing_iter.next();
1817                    to_remove.push(existing_id);
1818                    continue;
1819                }
1820                (Some(_), None) => {
1821                    added_a_new_excerpt = true;
1822                    let new_id = next_excerpt_id();
1823                    excerpt_ids.push(new_id);
1824                    to_insert.push((new_id, new_iter.next().unwrap()));
1825                    continue;
1826                }
1827                (Some(new), Some((_, existing_range))) => {
1828                    if existing_range.end < new.context.start {
1829                        let existing_id = existing_iter.next().unwrap();
1830                        to_remove.push(existing_id);
1831                        continue;
1832                    } else if existing_range.start > new.context.end {
1833                        let new_id = next_excerpt_id();
1834                        excerpt_ids.push(new_id);
1835                        to_insert.push((new_id, new_iter.next().unwrap()));
1836                        continue;
1837                    }
1838
1839                    if existing_range.start == new.context.start
1840                        && existing_range.end == new.context.end
1841                    {
1842                        self.insert_excerpts_with_ids_after(
1843                            insert_after,
1844                            buffer.clone(),
1845                            mem::take(&mut to_insert),
1846                            cx,
1847                        );
1848                        insert_after = existing_iter.next().unwrap();
1849                        excerpt_ids.push(insert_after);
1850                        new_iter.next();
1851                    } else {
1852                        let existing_id = existing_iter.next().unwrap();
1853                        let new_id = next_excerpt_id();
1854                        self.snapshot
1855                            .borrow_mut()
1856                            .replaced_excerpts
1857                            .insert(existing_id, new_id);
1858                        to_remove.push(existing_id);
1859                        let mut range = new_iter.next().unwrap();
1860                        range.context.start = range.context.start.min(existing_range.start);
1861                        range.context.end = range.context.end.max(existing_range.end);
1862                        excerpt_ids.push(new_id);
1863                        to_insert.push((new_id, range));
1864                    }
1865                }
1866            };
1867        }
1868
1869        self.insert_excerpts_with_ids_after(insert_after, buffer, to_insert, cx);
1870        self.remove_excerpts(to_remove, cx);
1871        if excerpt_ids.is_empty() {
1872            self.excerpts_by_path.remove(&path);
1873        } else {
1874            for excerpt_id in &excerpt_ids {
1875                self.paths_by_excerpt.insert(*excerpt_id, path.clone());
1876            }
1877            self.excerpts_by_path
1878                .insert(path, excerpt_ids.iter().dedup().cloned().collect());
1879        }
1880
1881        (excerpt_ids, added_a_new_excerpt)
1882    }
1883
1884    pub fn paths(&self) -> impl Iterator<Item = PathKey> + '_ {
1885        self.excerpts_by_path.keys().cloned()
1886    }
1887
1888    pub fn remove_excerpts_for_path(&mut self, path: PathKey, cx: &mut Context<Self>) {
1889        if let Some(to_remove) = self.excerpts_by_path.remove(&path) {
1890            self.remove_excerpts(to_remove, cx)
1891        }
1892    }
1893
1894    pub fn insert_excerpts_after<O>(
1895        &mut self,
1896        prev_excerpt_id: ExcerptId,
1897        buffer: Entity<Buffer>,
1898        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1899        cx: &mut Context<Self>,
1900    ) -> Vec<ExcerptId>
1901    where
1902        O: text::ToOffset,
1903    {
1904        let mut ids = Vec::new();
1905        let mut next_excerpt_id =
1906            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1907                last_entry.id.0 + 1
1908            } else {
1909                1
1910            };
1911        self.insert_excerpts_with_ids_after(
1912            prev_excerpt_id,
1913            buffer,
1914            ranges.into_iter().map(|range| {
1915                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1916                ids.push(id);
1917                (id, range)
1918            }),
1919            cx,
1920        );
1921        ids
1922    }
1923
1924    pub fn insert_excerpts_with_ids_after<O>(
1925        &mut self,
1926        prev_excerpt_id: ExcerptId,
1927        buffer: Entity<Buffer>,
1928        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1929        cx: &mut Context<Self>,
1930    ) where
1931        O: text::ToOffset,
1932    {
1933        assert_eq!(self.history.transaction_depth, 0);
1934        let mut ranges = ranges.into_iter().peekable();
1935        if ranges.peek().is_none() {
1936            return Default::default();
1937        }
1938
1939        self.sync(cx);
1940
1941        let buffer_snapshot = buffer.read(cx).snapshot();
1942        let buffer_id = buffer_snapshot.remote_id();
1943
1944        let mut buffers = self.buffers.borrow_mut();
1945        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| {
1946            self.buffer_changed_since_sync.replace(true);
1947            buffer.update(cx, |buffer, _| {
1948                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1949            });
1950            BufferState {
1951                last_version: buffer_snapshot.version().clone(),
1952                last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1953                excerpts: Default::default(),
1954                _subscriptions: [
1955                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1956                    cx.subscribe(&buffer, Self::on_buffer_event),
1957                ],
1958                buffer: buffer.clone(),
1959            }
1960        });
1961
1962        let mut snapshot = self.snapshot.borrow_mut();
1963
1964        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1965        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1966        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1967        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1968        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1969
1970        let edit_start = ExcerptOffset::new(new_excerpts.summary().text.len);
1971        new_excerpts.update_last(
1972            |excerpt| {
1973                excerpt.has_trailing_newline = true;
1974            },
1975            (),
1976        );
1977
1978        let next_locator = if let Some(excerpt) = cursor.item() {
1979            excerpt.locator.clone()
1980        } else {
1981            Locator::max()
1982        };
1983
1984        let mut excerpts = Vec::new();
1985        while let Some((id, range)) = ranges.next() {
1986            let locator = Locator::between(&prev_locator, &next_locator);
1987            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1988                buffer_state.excerpts.insert(ix, locator.clone());
1989            }
1990            let range = ExcerptRange {
1991                context: buffer_snapshot.anchor_before(&range.context.start)
1992                    ..buffer_snapshot.anchor_after(&range.context.end),
1993                primary: buffer_snapshot.anchor_before(&range.primary.start)
1994                    ..buffer_snapshot.anchor_after(&range.primary.end),
1995            };
1996            excerpts.push((id, range.clone()));
1997            let excerpt = Excerpt::new(
1998                id,
1999                locator.clone(),
2000                buffer_id,
2001                buffer_snapshot.clone(),
2002                range,
2003                ranges.peek().is_some() || cursor.item().is_some(),
2004            );
2005            new_excerpts.push(excerpt, ());
2006            prev_locator = locator.clone();
2007
2008            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
2009                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
2010            }
2011            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
2012        }
2013
2014        let edit_end = ExcerptOffset::new(new_excerpts.summary().text.len);
2015
2016        let suffix = cursor.suffix();
2017        let changed_trailing_excerpt = suffix.is_empty();
2018        new_excerpts.append(suffix, ());
2019        drop(cursor);
2020        snapshot.excerpts = new_excerpts;
2021        snapshot.excerpt_ids = new_excerpt_ids;
2022        if changed_trailing_excerpt {
2023            snapshot.trailing_excerpt_update_count += 1;
2024        }
2025
2026        self.sync_diff_transforms(
2027            &mut snapshot,
2028            vec![Edit {
2029                old: edit_start..edit_start,
2030                new: edit_start..edit_end,
2031            }],
2032            DiffChangeKind::BufferEdited,
2033        );
2034        cx.emit(Event::Edited {
2035            edited_buffer: None,
2036        });
2037        cx.emit(Event::ExcerptsAdded {
2038            buffer,
2039            predecessor: prev_excerpt_id,
2040            excerpts,
2041        });
2042        cx.notify();
2043    }
2044
2045    pub fn clear(&mut self, cx: &mut Context<Self>) {
2046        self.sync(cx);
2047        let ids = self.excerpt_ids();
2048        let removed_buffer_ids = self
2049            .buffers
2050            .borrow_mut()
2051            .drain()
2052            .map(|(id, _)| id)
2053            .collect();
2054        self.excerpts_by_path.clear();
2055        self.paths_by_excerpt.clear();
2056        let mut snapshot = self.snapshot.borrow_mut();
2057        let start = ExcerptOffset::new(0);
2058        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2059        snapshot.excerpts = Default::default();
2060        snapshot.trailing_excerpt_update_count += 1;
2061        snapshot.is_dirty = false;
2062        snapshot.has_deleted_file = false;
2063        snapshot.has_conflict = false;
2064        snapshot.replaced_excerpts.clear();
2065
2066        self.sync_diff_transforms(
2067            &mut snapshot,
2068            vec![Edit {
2069                old: start..prev_len,
2070                new: start..start,
2071            }],
2072            DiffChangeKind::BufferEdited,
2073        );
2074        cx.emit(Event::Edited {
2075            edited_buffer: None,
2076        });
2077        cx.emit(Event::ExcerptsRemoved {
2078            ids,
2079            removed_buffer_ids,
2080        });
2081        cx.notify();
2082    }
2083
2084    pub fn excerpts_for_buffer(
2085        &self,
2086        buffer_id: BufferId,
2087        cx: &App,
2088    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2089        let mut excerpts = Vec::new();
2090        let snapshot = self.read(cx);
2091        let buffers = self.buffers.borrow();
2092        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
2093        if let Some(locators) = buffers.get(&buffer_id).map(|state| &state.excerpts) {
2094            for locator in locators {
2095                cursor.seek_forward(&Some(locator), Bias::Left);
2096                if let Some(excerpt) = cursor.item()
2097                    && excerpt.locator == *locator
2098                {
2099                    excerpts.push((excerpt.id, excerpt.range.clone()));
2100                }
2101            }
2102        }
2103
2104        excerpts
2105    }
2106
2107    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2108        let snapshot = self.read(cx);
2109        let buffers = self.buffers.borrow();
2110        let mut excerpts = snapshot
2111            .excerpts
2112            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
2113        let mut diff_transforms = snapshot
2114            .diff_transforms
2115            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
2116        diff_transforms.next();
2117        let locators = buffers
2118            .get(&buffer_id)
2119            .into_iter()
2120            .flat_map(|state| &state.excerpts);
2121        let mut result = Vec::new();
2122        for locator in locators {
2123            excerpts.seek_forward(&Some(locator), Bias::Left);
2124            if let Some(excerpt) = excerpts.item()
2125                && excerpt.locator == *locator
2126            {
2127                let excerpt_start = excerpts.start().1.clone();
2128                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2129
2130                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2131                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2132                let start = diff_transforms.start().1.0 + overshoot;
2133
2134                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2135                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2136                let end = diff_transforms.start().1.0 + overshoot;
2137
2138                result.push(start..end)
2139            }
2140        }
2141        result
2142    }
2143
2144    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2145        self.snapshot
2146            .borrow()
2147            .excerpts
2148            .iter()
2149            .map(|entry| entry.buffer_id)
2150            .collect()
2151    }
2152
2153    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2154        self.snapshot
2155            .borrow()
2156            .excerpts
2157            .iter()
2158            .map(|entry| entry.id)
2159            .collect()
2160    }
2161
2162    pub fn excerpt_containing(
2163        &self,
2164        position: impl ToOffset,
2165        cx: &App,
2166    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2167        let snapshot = self.read(cx);
2168        let offset = position.to_offset(&snapshot);
2169
2170        let mut cursor = snapshot.cursor::<usize>();
2171        cursor.seek(&offset);
2172        cursor
2173            .excerpt()
2174            .or_else(|| snapshot.excerpts.last())
2175            .map(|excerpt| {
2176                (
2177                    excerpt.id,
2178                    self.buffers
2179                        .borrow()
2180                        .get(&excerpt.buffer_id)
2181                        .unwrap()
2182                        .buffer
2183                        .clone(),
2184                    excerpt.range.context.clone(),
2185                )
2186            })
2187    }
2188
2189    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2190        if let Some(buffer_id) = anchor.buffer_id {
2191            self.buffer(buffer_id)
2192        } else {
2193            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2194            Some(buffer)
2195        }
2196    }
2197
2198    // If point is at the end of the buffer, the last excerpt is returned
2199    pub fn point_to_buffer_offset<T: ToOffset>(
2200        &self,
2201        point: T,
2202        cx: &App,
2203    ) -> Option<(Entity<Buffer>, usize)> {
2204        let snapshot = self.read(cx);
2205        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2206        Some((
2207            self.buffers
2208                .borrow()
2209                .get(&buffer.remote_id())?
2210                .buffer
2211                .clone(),
2212            offset,
2213        ))
2214    }
2215
2216    // If point is at the end of the buffer, the last excerpt is returned
2217    pub fn point_to_buffer_point<T: ToPoint>(
2218        &self,
2219        point: T,
2220        cx: &App,
2221    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2222        let snapshot = self.read(cx);
2223        let (buffer, point, is_main_buffer) =
2224            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2225        Some((
2226            self.buffers
2227                .borrow()
2228                .get(&buffer.remote_id())?
2229                .buffer
2230                .clone(),
2231            point,
2232            is_main_buffer,
2233        ))
2234    }
2235
2236    pub fn buffer_point_to_anchor(
2237        &self,
2238        buffer: &Entity<Buffer>,
2239        point: Point,
2240        cx: &App,
2241    ) -> Option<Anchor> {
2242        let mut found = None;
2243        let snapshot = buffer.read(cx).snapshot();
2244        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2245            let start = range.context.start.to_point(&snapshot);
2246            let end = range.context.end.to_point(&snapshot);
2247            if start <= point && point < end {
2248                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2249                break;
2250            }
2251            if point < start {
2252                found = Some((start, excerpt_id));
2253            }
2254            if point > end {
2255                found = Some((end, excerpt_id));
2256            }
2257        }
2258
2259        found.map(|(point, excerpt_id)| {
2260            let text_anchor = snapshot.anchor_after(point);
2261            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2262        })
2263    }
2264
2265    pub fn remove_excerpts(
2266        &mut self,
2267        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2268        cx: &mut Context<Self>,
2269    ) {
2270        self.sync(cx);
2271        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2272        if ids.is_empty() {
2273            return;
2274        }
2275
2276        let mut buffers = self.buffers.borrow_mut();
2277        let mut snapshot = self.snapshot.borrow_mut();
2278        let mut new_excerpts = SumTree::default();
2279        let mut cursor = snapshot
2280            .excerpts
2281            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2282        let mut edits = Vec::new();
2283        let mut excerpt_ids = ids.iter().copied().peekable();
2284        let mut removed_buffer_ids = Vec::new();
2285
2286        while let Some(excerpt_id) = excerpt_ids.next() {
2287            self.paths_by_excerpt.remove(&excerpt_id);
2288            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2289            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2290            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2291
2292            if let Some(mut excerpt) = cursor.item() {
2293                if excerpt.id != excerpt_id {
2294                    continue;
2295                }
2296                let mut old_start = cursor.start().1;
2297
2298                // Skip over the removed excerpt.
2299                'remove_excerpts: loop {
2300                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2301                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2302                        if buffer_state.excerpts.is_empty() {
2303                            log::debug!(
2304                                "removing buffer and diff for buffer {}",
2305                                excerpt.buffer_id
2306                            );
2307                            buffers.remove(&excerpt.buffer_id);
2308                            removed_buffer_ids.push(excerpt.buffer_id);
2309                        }
2310                    }
2311                    cursor.next();
2312
2313                    // Skip over any subsequent excerpts that are also removed.
2314                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2315                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2316                        if let Some(next_excerpt) = cursor.item()
2317                            && next_excerpt.locator == *next_locator
2318                        {
2319                            excerpt_ids.next();
2320                            excerpt = next_excerpt;
2321                            continue 'remove_excerpts;
2322                        }
2323                    }
2324
2325                    break;
2326                }
2327
2328                // When removing the last excerpt, remove the trailing newline from
2329                // the previous excerpt.
2330                if cursor.item().is_none() && old_start.value > 0 {
2331                    old_start.value -= 1;
2332                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2333                }
2334
2335                // Push an edit for the removal of this run of excerpts.
2336                let old_end = cursor.start().1;
2337                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2338                edits.push(Edit {
2339                    old: old_start..old_end,
2340                    new: new_start..new_start,
2341                });
2342            }
2343        }
2344        let suffix = cursor.suffix();
2345        let changed_trailing_excerpt = suffix.is_empty();
2346        new_excerpts.append(suffix, ());
2347        drop(cursor);
2348        snapshot.excerpts = new_excerpts;
2349        for buffer_id in &removed_buffer_ids {
2350            self.diffs.remove(buffer_id);
2351            snapshot.diffs.remove(buffer_id);
2352        }
2353
2354        if changed_trailing_excerpt {
2355            snapshot.trailing_excerpt_update_count += 1;
2356        }
2357
2358        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2359        self.buffer_changed_since_sync.replace(true);
2360        cx.emit(Event::Edited {
2361            edited_buffer: None,
2362        });
2363        cx.emit(Event::ExcerptsRemoved {
2364            ids,
2365            removed_buffer_ids,
2366        });
2367        cx.notify();
2368    }
2369
2370    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2371        &self,
2372        anchors: Anchors,
2373        cx: &mut Context<Self>,
2374    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2375        let borrow = self.buffers.borrow();
2376        let mut error = None;
2377        let mut futures = Vec::new();
2378        for anchor in anchors {
2379            if let Some(buffer_id) = anchor.buffer_id {
2380                if let Some(buffer) = borrow.get(&buffer_id) {
2381                    buffer.buffer.update(cx, |buffer, _| {
2382                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2383                    });
2384                } else {
2385                    error = Some(anyhow!(
2386                        "buffer {buffer_id} is not part of this multi-buffer"
2387                    ));
2388                    break;
2389                }
2390            }
2391        }
2392        async move {
2393            if let Some(error) = error {
2394                Err(error)?;
2395            }
2396            for future in futures {
2397                future.await?;
2398            }
2399            Ok(())
2400        }
2401    }
2402
2403    pub fn text_anchor_for_position<T: ToOffset>(
2404        &self,
2405        position: T,
2406        cx: &App,
2407    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2408        let snapshot = self.read(cx);
2409        let anchor = snapshot.anchor_before(position);
2410        let buffer = self
2411            .buffers
2412            .borrow()
2413            .get(&anchor.buffer_id?)?
2414            .buffer
2415            .clone();
2416        Some((buffer, anchor.text_anchor))
2417    }
2418
2419    fn on_buffer_event(
2420        &mut self,
2421        buffer: Entity<Buffer>,
2422        event: &language::BufferEvent,
2423        cx: &mut Context<Self>,
2424    ) {
2425        use language::BufferEvent;
2426        cx.emit(match event {
2427            BufferEvent::Edited => Event::Edited {
2428                edited_buffer: Some(buffer),
2429            },
2430            BufferEvent::DirtyChanged => Event::DirtyChanged,
2431            BufferEvent::Saved => Event::Saved,
2432            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2433            BufferEvent::Reloaded => Event::Reloaded,
2434            BufferEvent::LanguageChanged => Event::LanguageChanged(buffer.read(cx).remote_id()),
2435            BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2436            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2437            BufferEvent::CapabilityChanged => {
2438                self.capability = buffer.read(cx).capability();
2439                return;
2440            }
2441            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2442        });
2443    }
2444
2445    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2446        self.sync(cx);
2447        let mut snapshot = self.snapshot.borrow_mut();
2448        let diff = diff.read(cx);
2449        let buffer_id = diff.buffer_id;
2450        let diff = diff.snapshot(cx);
2451        snapshot.diffs.insert(buffer_id, diff);
2452    }
2453
2454    fn buffer_diff_changed(
2455        &mut self,
2456        diff: Entity<BufferDiff>,
2457        range: Range<text::Anchor>,
2458        cx: &mut Context<Self>,
2459    ) {
2460        self.sync(cx);
2461        self.buffer_changed_since_sync.replace(true);
2462
2463        let diff = diff.read(cx);
2464        let buffer_id = diff.buffer_id;
2465        let buffers = self.buffers.borrow();
2466        let Some(buffer_state) = buffers.get(&buffer_id) else {
2467            return;
2468        };
2469
2470        let buffer = buffer_state.buffer.read(cx);
2471        let diff_change_range = range.to_offset(buffer);
2472
2473        let new_diff = diff.snapshot(cx);
2474        let mut snapshot = self.snapshot.borrow_mut();
2475        let base_text_changed = snapshot
2476            .diffs
2477            .get(&buffer_id)
2478            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2479
2480        snapshot.diffs.insert(buffer_id, new_diff);
2481
2482        let mut excerpt_edits = Vec::new();
2483        for locator in &buffer_state.excerpts {
2484            let mut cursor = snapshot
2485                .excerpts
2486                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2487            cursor.seek_forward(&Some(locator), Bias::Left);
2488            if let Some(excerpt) = cursor.item()
2489                && excerpt.locator == *locator
2490            {
2491                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2492                if diff_change_range.end < excerpt_buffer_range.start
2493                    || diff_change_range.start > excerpt_buffer_range.end
2494                {
2495                    continue;
2496                }
2497                let excerpt_start = cursor.start().1;
2498                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2499                let diff_change_start_in_excerpt = ExcerptOffset::new(
2500                    diff_change_range
2501                        .start
2502                        .saturating_sub(excerpt_buffer_range.start),
2503                );
2504                let diff_change_end_in_excerpt = ExcerptOffset::new(
2505                    diff_change_range
2506                        .end
2507                        .saturating_sub(excerpt_buffer_range.start),
2508                );
2509                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2510                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2511                excerpt_edits.push(Edit {
2512                    old: edit_start..edit_end,
2513                    new: edit_start..edit_end,
2514                });
2515            }
2516        }
2517
2518        self.sync_diff_transforms(
2519            &mut snapshot,
2520            excerpt_edits,
2521            DiffChangeKind::DiffUpdated {
2522                base_changed: base_text_changed,
2523            },
2524        );
2525        cx.emit(Event::Edited {
2526            edited_buffer: None,
2527        });
2528    }
2529
2530    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2531        self.buffers
2532            .borrow()
2533            .values()
2534            .map(|state| state.buffer.clone())
2535            .collect()
2536    }
2537
2538    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2539        self.buffers.borrow().keys().copied().collect()
2540    }
2541
2542    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2543        self.buffers
2544            .borrow()
2545            .get(&buffer_id)
2546            .map(|state| state.buffer.clone())
2547    }
2548
2549    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2550        self.point_to_buffer_offset(point, cx)
2551            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2552    }
2553
2554    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2555        let buffer_id = self
2556            .snapshot
2557            .borrow()
2558            .excerpts
2559            .first()
2560            .map(|excerpt| excerpt.buffer.remote_id());
2561        buffer_id
2562            .and_then(|buffer_id| self.buffer(buffer_id))
2563            .map(|buffer| {
2564                let buffer = buffer.read(cx);
2565                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2566            })
2567            .unwrap_or_else(move || self.language_settings_at(0, cx))
2568    }
2569
2570    pub fn language_settings_at<'a, T: ToOffset>(
2571        &'a self,
2572        point: T,
2573        cx: &'a App,
2574    ) -> Cow<'a, LanguageSettings> {
2575        let mut language = None;
2576        let mut file = None;
2577        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2578            let buffer = buffer.read(cx);
2579            language = buffer.language_at(offset);
2580            file = buffer.file();
2581        }
2582        language_settings(language.map(|l| l.name()), file, cx)
2583    }
2584
2585    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2586        self.buffers
2587            .borrow()
2588            .values()
2589            .for_each(|state| f(&state.buffer))
2590    }
2591
2592    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2593        if let Some(title) = self.title.as_ref() {
2594            return title.into();
2595        }
2596
2597        if let Some(buffer) = self.as_singleton() {
2598            let buffer = buffer.read(cx);
2599
2600            if let Some(file) = buffer.file() {
2601                return file.file_name(cx).into();
2602            }
2603
2604            if let Some(title) = self.buffer_content_title(buffer) {
2605                return title;
2606            }
2607        };
2608
2609        "untitled".into()
2610    }
2611
2612    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2613        let mut is_leading_whitespace = true;
2614        let mut count = 0;
2615        let mut prev_was_space = false;
2616        let mut title = String::new();
2617
2618        for ch in buffer.snapshot().chars() {
2619            if is_leading_whitespace && ch.is_whitespace() {
2620                continue;
2621            }
2622
2623            is_leading_whitespace = false;
2624
2625            if ch == '\n' || count >= 40 {
2626                break;
2627            }
2628
2629            if ch.is_whitespace() {
2630                if !prev_was_space {
2631                    title.push(' ');
2632                    count += 1;
2633                    prev_was_space = true;
2634                }
2635            } else {
2636                title.push(ch);
2637                count += 1;
2638                prev_was_space = false;
2639            }
2640        }
2641
2642        let title = title.trim_end().to_string();
2643
2644        if title.is_empty() {
2645            return None;
2646        }
2647
2648        Some(title.into())
2649    }
2650
2651    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2652        self.title = Some(title);
2653        cx.notify();
2654    }
2655
2656    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2657    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2658        for buffer_state in self.buffers.borrow().values() {
2659            buffer_state
2660                .buffer
2661                .update(cx, |buffer, _cx| buffer.refresh_preview());
2662        }
2663    }
2664
2665    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2666    pub fn preserve_preview(&self, cx: &App) -> bool {
2667        self.buffers
2668            .borrow()
2669            .values()
2670            .all(|state| state.buffer.read(cx).preserve_preview())
2671    }
2672
2673    #[cfg(any(test, feature = "test-support"))]
2674    pub fn is_parsing(&self, cx: &App) -> bool {
2675        self.as_singleton().unwrap().read(cx).is_parsing()
2676    }
2677
2678    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2679        let buffer_id = diff.read(cx).buffer_id;
2680        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2681        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2682    }
2683
2684    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2685        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2686    }
2687
2688    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2689        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2690    }
2691
2692    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2693        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2694    }
2695
2696    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2697        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2698        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2699    }
2700
2701    pub fn all_diff_hunks_expanded(&self) -> bool {
2702        self.snapshot.borrow().all_diff_hunks_expanded
2703    }
2704
2705    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2706        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2707        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2708    }
2709
2710    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2711        self.read(cx)
2712            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2713            .nth(1)
2714            .is_some()
2715    }
2716
2717    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2718        let snapshot = self.read(cx);
2719        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2720        let offset_range = range.to_offset(&snapshot);
2721        cursor.seek(&offset_range.start, Bias::Left);
2722        while let Some(item) = cursor.item() {
2723            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2724                break;
2725            }
2726            if item.hunk_info().is_some() {
2727                return true;
2728            }
2729            cursor.next();
2730        }
2731        false
2732    }
2733
2734    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2735        let snapshot = self.read(cx);
2736        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2737        for range in ranges {
2738            let range = range.to_point(&snapshot);
2739            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2740            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2741            let start = start.saturating_sub(1);
2742            let end = snapshot.len().min(end + 1);
2743            cursor.seek(&start, Bias::Right);
2744            while let Some(item) = cursor.item() {
2745                if *cursor.start() >= end {
2746                    break;
2747                }
2748                if item.hunk_info().is_some() {
2749                    return true;
2750                }
2751                cursor.next();
2752            }
2753        }
2754        false
2755    }
2756
2757    pub fn expand_or_collapse_diff_hunks_inner(
2758        &mut self,
2759        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2760        expand: bool,
2761        cx: &mut Context<Self>,
2762    ) {
2763        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2764            return;
2765        }
2766        self.sync(cx);
2767        let mut snapshot = self.snapshot.borrow_mut();
2768        let mut excerpt_edits = Vec::new();
2769        let mut last_hunk_row = None;
2770        for (range, end_excerpt_id) in ranges {
2771            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2772                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2773                    continue;
2774                }
2775                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2776                    continue;
2777                }
2778                let start = Anchor::in_buffer(
2779                    diff_hunk.excerpt_id,
2780                    diff_hunk.buffer_id,
2781                    diff_hunk.buffer_range.start,
2782                );
2783                let end = Anchor::in_buffer(
2784                    diff_hunk.excerpt_id,
2785                    diff_hunk.buffer_id,
2786                    diff_hunk.buffer_range.end,
2787                );
2788                let start = snapshot.excerpt_offset_for_anchor(&start);
2789                let end = snapshot.excerpt_offset_for_anchor(&end);
2790                last_hunk_row = Some(diff_hunk.row_range.start);
2791                excerpt_edits.push(text::Edit {
2792                    old: start..end,
2793                    new: start..end,
2794                });
2795            }
2796        }
2797
2798        self.sync_diff_transforms(
2799            &mut snapshot,
2800            excerpt_edits,
2801            DiffChangeKind::ExpandOrCollapseHunks { expand },
2802        );
2803        cx.emit(Event::DiffHunksToggled);
2804        cx.emit(Event::Edited {
2805            edited_buffer: None,
2806        });
2807    }
2808
2809    pub fn expand_or_collapse_diff_hunks(
2810        &mut self,
2811        ranges: Vec<Range<Anchor>>,
2812        expand: bool,
2813        cx: &mut Context<Self>,
2814    ) {
2815        let snapshot = self.snapshot.borrow().clone();
2816        let ranges = ranges.iter().map(move |range| {
2817            let end_excerpt_id = range.end.excerpt_id;
2818            let range = range.to_point(&snapshot);
2819            let mut peek_end = range.end;
2820            if range.end.row < snapshot.max_row().0 {
2821                peek_end = Point::new(range.end.row + 1, 0);
2822            };
2823            (range.start..peek_end, end_excerpt_id)
2824        });
2825        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2826    }
2827
2828    pub fn resize_excerpt(
2829        &mut self,
2830        id: ExcerptId,
2831        range: Range<text::Anchor>,
2832        cx: &mut Context<Self>,
2833    ) {
2834        self.sync(cx);
2835
2836        let mut snapshot = self.snapshot.borrow_mut();
2837        let locator = snapshot.excerpt_locator_for_id(id);
2838        let mut new_excerpts = SumTree::default();
2839        let mut cursor = snapshot
2840            .excerpts
2841            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2842        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2843
2844        let prefix = cursor.slice(&Some(locator), Bias::Left);
2845        new_excerpts.append(prefix, ());
2846
2847        let mut excerpt = cursor.item().unwrap().clone();
2848        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2849
2850        excerpt.range.context.start = range.start;
2851        excerpt.range.context.end = range.end;
2852        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2853
2854        excerpt.text_summary = excerpt
2855            .buffer
2856            .text_summary_for_range(excerpt.range.context.clone());
2857
2858        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2859        let old_start_offset = cursor.start().1;
2860        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2861        let edit = Edit {
2862            old: old_start_offset..old_start_offset + old_text_len,
2863            new: new_start_offset..new_start_offset + new_text_len,
2864        };
2865
2866        if let Some(last_edit) = edits.last_mut() {
2867            if last_edit.old.end == edit.old.start {
2868                last_edit.old.end = edit.old.end;
2869                last_edit.new.end = edit.new.end;
2870            } else {
2871                edits.push(edit);
2872            }
2873        } else {
2874            edits.push(edit);
2875        }
2876
2877        new_excerpts.push(excerpt, ());
2878
2879        cursor.next();
2880
2881        new_excerpts.append(cursor.suffix(), ());
2882
2883        drop(cursor);
2884        snapshot.excerpts = new_excerpts;
2885
2886        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2887        cx.emit(Event::Edited {
2888            edited_buffer: None,
2889        });
2890        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2891        cx.notify();
2892    }
2893
2894    pub fn expand_excerpts(
2895        &mut self,
2896        ids: impl IntoIterator<Item = ExcerptId>,
2897        line_count: u32,
2898        direction: ExpandExcerptDirection,
2899        cx: &mut Context<Self>,
2900    ) {
2901        if line_count == 0 {
2902            return;
2903        }
2904        self.sync(cx);
2905        if !self.excerpts_by_path.is_empty() {
2906            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2907            return;
2908        }
2909        let mut snapshot = self.snapshot.borrow_mut();
2910
2911        let ids = ids.into_iter().collect::<Vec<_>>();
2912        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2913        let mut new_excerpts = SumTree::default();
2914        let mut cursor = snapshot
2915            .excerpts
2916            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2917        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2918
2919        for locator in &locators {
2920            let prefix = cursor.slice(&Some(locator), Bias::Left);
2921            new_excerpts.append(prefix, ());
2922
2923            let mut excerpt = cursor.item().unwrap().clone();
2924            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2925
2926            let up_line_count = if direction.should_expand_up() {
2927                line_count
2928            } else {
2929                0
2930            };
2931
2932            let start_row = excerpt
2933                .range
2934                .context
2935                .start
2936                .to_point(&excerpt.buffer)
2937                .row
2938                .saturating_sub(up_line_count);
2939            let start_point = Point::new(start_row, 0);
2940            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2941
2942            let down_line_count = if direction.should_expand_down() {
2943                line_count
2944            } else {
2945                0
2946            };
2947
2948            let mut end_point = excerpt.buffer.clip_point(
2949                excerpt.range.context.end.to_point(&excerpt.buffer)
2950                    + Point::new(down_line_count, 0),
2951                Bias::Left,
2952            );
2953            end_point.column = excerpt.buffer.line_len(end_point.row);
2954            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2955            excerpt.max_buffer_row = end_point.row;
2956
2957            excerpt.text_summary = excerpt
2958                .buffer
2959                .text_summary_for_range(excerpt.range.context.clone());
2960
2961            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2962            let old_start_offset = cursor.start().1;
2963            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2964            let edit = Edit {
2965                old: old_start_offset..old_start_offset + old_text_len,
2966                new: new_start_offset..new_start_offset + new_text_len,
2967            };
2968
2969            if let Some(last_edit) = edits.last_mut() {
2970                if last_edit.old.end == edit.old.start {
2971                    last_edit.old.end = edit.old.end;
2972                    last_edit.new.end = edit.new.end;
2973                } else {
2974                    edits.push(edit);
2975                }
2976            } else {
2977                edits.push(edit);
2978            }
2979
2980            new_excerpts.push(excerpt, ());
2981
2982            cursor.next();
2983        }
2984
2985        new_excerpts.append(cursor.suffix(), ());
2986
2987        drop(cursor);
2988        snapshot.excerpts = new_excerpts;
2989
2990        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2991        cx.emit(Event::Edited {
2992            edited_buffer: None,
2993        });
2994        cx.emit(Event::ExcerptsExpanded { ids });
2995        cx.notify();
2996    }
2997
2998    fn sync(&self, cx: &App) {
2999        let changed = self.buffer_changed_since_sync.replace(false);
3000        if !changed {
3001            return;
3002        }
3003
3004        let mut snapshot = self.snapshot.borrow_mut();
3005        let mut excerpts_to_edit = Vec::new();
3006        let mut non_text_state_updated = false;
3007        let mut is_dirty = false;
3008        let mut has_deleted_file = false;
3009        let mut has_conflict = false;
3010        let mut edited = false;
3011        let mut buffers = self.buffers.borrow_mut();
3012        for buffer_state in buffers.values_mut() {
3013            let buffer = buffer_state.buffer.read(cx);
3014            let version = buffer.version();
3015            let non_text_state_update_count = buffer.non_text_state_update_count();
3016
3017            let buffer_edited = version.changed_since(&buffer_state.last_version);
3018            let buffer_non_text_state_updated =
3019                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3020            if buffer_edited || buffer_non_text_state_updated {
3021                buffer_state.last_version = version;
3022                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3023                excerpts_to_edit.extend(
3024                    buffer_state
3025                        .excerpts
3026                        .iter()
3027                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3028                );
3029            }
3030
3031            edited |= buffer_edited;
3032            non_text_state_updated |= buffer_non_text_state_updated;
3033            is_dirty |= buffer.is_dirty();
3034            has_deleted_file |= buffer
3035                .file()
3036                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3037            has_conflict |= buffer.has_conflict();
3038        }
3039        if edited {
3040            snapshot.edit_count += 1;
3041        }
3042        if non_text_state_updated {
3043            snapshot.non_text_state_update_count += 1;
3044        }
3045        snapshot.is_dirty = is_dirty;
3046        snapshot.has_deleted_file = has_deleted_file;
3047        snapshot.has_conflict = has_conflict;
3048
3049        for (id, diff) in self.diffs.iter() {
3050            if snapshot.diffs.get(id).is_none() {
3051                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3052            }
3053        }
3054
3055        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3056
3057        let mut edits = Vec::new();
3058        let mut new_excerpts = SumTree::default();
3059        let mut cursor = snapshot
3060            .excerpts
3061            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3062
3063        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3064            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3065            let old_excerpt = cursor.item().unwrap();
3066            let buffer = buffer.read(cx);
3067            let buffer_id = buffer.remote_id();
3068
3069            let mut new_excerpt;
3070            if buffer_edited {
3071                edits.extend(
3072                    buffer
3073                        .edits_since_in_range::<usize>(
3074                            old_excerpt.buffer.version(),
3075                            old_excerpt.range.context.clone(),
3076                        )
3077                        .map(|edit| {
3078                            let excerpt_old_start = cursor.start().1;
3079                            let excerpt_new_start =
3080                                ExcerptOffset::new(new_excerpts.summary().text.len);
3081                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3082                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3083                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3084                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3085                            Edit {
3086                                old: old_start..old_end,
3087                                new: new_start..new_end,
3088                            }
3089                        }),
3090                );
3091
3092                new_excerpt = Excerpt::new(
3093                    old_excerpt.id,
3094                    locator.clone(),
3095                    buffer_id,
3096                    buffer.snapshot(),
3097                    old_excerpt.range.clone(),
3098                    old_excerpt.has_trailing_newline,
3099                );
3100            } else {
3101                new_excerpt = old_excerpt.clone();
3102                new_excerpt.buffer = buffer.snapshot();
3103            }
3104
3105            new_excerpts.push(new_excerpt, ());
3106            cursor.next();
3107        }
3108        new_excerpts.append(cursor.suffix(), ());
3109
3110        drop(cursor);
3111        snapshot.excerpts = new_excerpts;
3112
3113        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3114    }
3115
3116    fn sync_diff_transforms(
3117        &self,
3118        snapshot: &mut MultiBufferSnapshot,
3119        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3120        change_kind: DiffChangeKind,
3121    ) {
3122        if excerpt_edits.is_empty() {
3123            return;
3124        }
3125
3126        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3127        let mut old_diff_transforms = snapshot
3128            .diff_transforms
3129            .cursor::<Dimensions<ExcerptOffset, usize>>(());
3130        let mut new_diff_transforms = SumTree::default();
3131        let mut old_expanded_hunks = HashSet::default();
3132        let mut output_edits = Vec::new();
3133        let mut output_delta = 0_isize;
3134        let mut at_transform_boundary = true;
3135        let mut end_of_current_insert = None;
3136
3137        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3138        while let Some(edit) = excerpt_edits.next() {
3139            excerpts.seek_forward(&edit.new.start, Bias::Right);
3140            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3141                excerpts.prev();
3142            }
3143
3144            // Keep any transforms that are before the edit.
3145            if at_transform_boundary {
3146                at_transform_boundary = false;
3147                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3148                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3149                if let Some(transform) = old_diff_transforms.item()
3150                    && old_diff_transforms.end().0 == edit.old.start
3151                    && old_diff_transforms.start().0 < edit.old.start
3152                {
3153                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3154                    old_diff_transforms.next();
3155                }
3156            }
3157
3158            // Compute the start of the edit in output coordinates.
3159            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3160            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3161            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3162
3163            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3164                &edit,
3165                &mut excerpts,
3166                &mut old_diff_transforms,
3167                &mut new_diff_transforms,
3168                &mut end_of_current_insert,
3169                &mut old_expanded_hunks,
3170                snapshot,
3171                change_kind,
3172            );
3173
3174            // Compute the end of the edit in output coordinates.
3175            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3176            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3177            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3178            let edit_new_end =
3179                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3180            let output_edit = Edit {
3181                old: edit_old_start..edit_old_end,
3182                new: edit_new_start..edit_new_end,
3183            };
3184
3185            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3186            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3187            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3188                output_edits.push(output_edit);
3189            }
3190
3191            // If this is the last edit that intersects the current diff transform,
3192            // then recreate the content up to the end of this transform, to prepare
3193            // for reusing additional slices of the old transforms.
3194            if excerpt_edits
3195                .peek()
3196                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3197            {
3198                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3199                    && match old_diff_transforms.item() {
3200                        Some(DiffTransform::BufferContent {
3201                            inserted_hunk_info: Some(hunk),
3202                            ..
3203                        }) => excerpts.item().is_some_and(|excerpt| {
3204                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3205                        }),
3206                        _ => true,
3207                    };
3208
3209                let mut excerpt_offset = edit.new.end;
3210                if !keep_next_old_transform {
3211                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3212                    old_diff_transforms.next();
3213                }
3214
3215                old_expanded_hunks.clear();
3216                self.push_buffer_content_transform(
3217                    snapshot,
3218                    &mut new_diff_transforms,
3219                    excerpt_offset,
3220                    end_of_current_insert,
3221                );
3222                at_transform_boundary = true;
3223            }
3224        }
3225
3226        // Keep any transforms that are after the last edit.
3227        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3228
3229        // Ensure there's always at least one buffer content transform.
3230        if new_diff_transforms.is_empty() {
3231            new_diff_transforms.push(
3232                DiffTransform::BufferContent {
3233                    summary: Default::default(),
3234                    inserted_hunk_info: None,
3235                },
3236                (),
3237            );
3238        }
3239
3240        self.subscriptions.publish(output_edits);
3241        drop(old_diff_transforms);
3242        drop(excerpts);
3243        snapshot.diff_transforms = new_diff_transforms;
3244        snapshot.edit_count += 1;
3245
3246        #[cfg(any(test, feature = "test-support"))]
3247        snapshot.check_invariants();
3248    }
3249
3250    fn recompute_diff_transforms_for_edit(
3251        &self,
3252        edit: &Edit<TypedOffset<Excerpt>>,
3253        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3254        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3255        new_diff_transforms: &mut SumTree<DiffTransform>,
3256        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3257        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3258        snapshot: &MultiBufferSnapshot,
3259        change_kind: DiffChangeKind,
3260    ) -> bool {
3261        log::trace!(
3262            "recomputing diff transform for edit {:?} => {:?}",
3263            edit.old.start.value..edit.old.end.value,
3264            edit.new.start.value..edit.new.end.value
3265        );
3266
3267        // Record which hunks were previously expanded.
3268        while let Some(item) = old_diff_transforms.item() {
3269            if let Some(hunk_info) = item.hunk_info() {
3270                log::trace!(
3271                    "previously expanded hunk at {}",
3272                    old_diff_transforms.start().0
3273                );
3274                old_expanded_hunks.insert(hunk_info);
3275            }
3276            if old_diff_transforms.end().0 > edit.old.end {
3277                break;
3278            }
3279            old_diff_transforms.next();
3280        }
3281
3282        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3283        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3284        if old_expanded_hunks.is_empty()
3285            && change_kind == DiffChangeKind::BufferEdited
3286            && !all_diff_hunks_expanded
3287        {
3288            return false;
3289        }
3290
3291        // Visit each excerpt that intersects the edit.
3292        let mut did_expand_hunks = false;
3293        while let Some(excerpt) = excerpts.item() {
3294            // Recompute the expanded hunks in the portion of the excerpt that
3295            // intersects the edit.
3296            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3297                let buffer = &excerpt.buffer;
3298                let excerpt_start = *excerpts.start();
3299                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3300                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3301                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3302                let edit_buffer_start =
3303                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3304                let edit_buffer_end =
3305                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3306                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3307                let edit_anchor_range =
3308                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3309
3310                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3311                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3312                        continue;
3313                    }
3314
3315                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3316                    if hunk_buffer_range.start < excerpt_buffer_start {
3317                        log::trace!("skipping hunk that starts before excerpt");
3318                        continue;
3319                    }
3320
3321                    let hunk_info = DiffTransformHunkInfo {
3322                        excerpt_id: excerpt.id,
3323                        hunk_start_anchor: hunk.buffer_range.start,
3324                        hunk_secondary_status: hunk.secondary_status,
3325                    };
3326
3327                    let hunk_excerpt_start = excerpt_start
3328                        + ExcerptOffset::new(
3329                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3330                        );
3331                    let hunk_excerpt_end = excerpt_end.min(
3332                        excerpt_start
3333                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3334                    );
3335
3336                    self.push_buffer_content_transform(
3337                        snapshot,
3338                        new_diff_transforms,
3339                        hunk_excerpt_start,
3340                        *end_of_current_insert,
3341                    );
3342
3343                    // For every existing hunk, determine if it was previously expanded
3344                    // and if it should currently be expanded.
3345                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3346                    let should_expand_hunk = match &change_kind {
3347                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3348                            was_previously_expanded || all_diff_hunks_expanded
3349                        }
3350                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3351                            let intersects = hunk_buffer_range.is_empty()
3352                                || hunk_buffer_range.end > edit_buffer_start;
3353                            if *expand {
3354                                intersects || was_previously_expanded || all_diff_hunks_expanded
3355                            } else {
3356                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3357                            }
3358                        }
3359                        _ => was_previously_expanded || all_diff_hunks_expanded,
3360                    };
3361
3362                    if should_expand_hunk {
3363                        did_expand_hunks = true;
3364                        log::trace!(
3365                            "expanding hunk {:?}, excerpt:{:?}",
3366                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3367                            excerpt.id
3368                        );
3369
3370                        if !hunk.diff_base_byte_range.is_empty()
3371                            && hunk_buffer_range.start >= edit_buffer_start
3372                            && hunk_buffer_range.start <= excerpt_buffer_end
3373                        {
3374                            let base_text = diff.base_text();
3375                            let mut text_cursor =
3376                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3377                            let mut base_text_summary =
3378                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3379
3380                            let mut has_trailing_newline = false;
3381                            if base_text_summary.last_line_chars > 0 {
3382                                base_text_summary += TextSummary::newline();
3383                                has_trailing_newline = true;
3384                            }
3385
3386                            new_diff_transforms.push(
3387                                DiffTransform::DeletedHunk {
3388                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3389                                    summary: base_text_summary,
3390                                    buffer_id: excerpt.buffer_id,
3391                                    hunk_info,
3392                                    has_trailing_newline,
3393                                },
3394                                (),
3395                            );
3396                        }
3397
3398                        if !hunk_buffer_range.is_empty() {
3399                            *end_of_current_insert =
3400                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3401                        }
3402                    }
3403                }
3404            }
3405
3406            if excerpts.end() <= edit.new.end {
3407                excerpts.next();
3408            } else {
3409                break;
3410            }
3411        }
3412
3413        did_expand_hunks || !old_expanded_hunks.is_empty()
3414    }
3415
3416    fn append_diff_transforms(
3417        &self,
3418        new_transforms: &mut SumTree<DiffTransform>,
3419        subtree: SumTree<DiffTransform>,
3420    ) {
3421        if let Some(DiffTransform::BufferContent {
3422            inserted_hunk_info,
3423            summary,
3424        }) = subtree.first()
3425            && self.extend_last_buffer_content_transform(
3426                new_transforms,
3427                *inserted_hunk_info,
3428                *summary,
3429            )
3430        {
3431            let mut cursor = subtree.cursor::<()>(());
3432            cursor.next();
3433            cursor.next();
3434            new_transforms.append(cursor.suffix(), ());
3435            return;
3436        }
3437        new_transforms.append(subtree, ());
3438    }
3439
3440    fn push_diff_transform(
3441        &self,
3442        new_transforms: &mut SumTree<DiffTransform>,
3443        transform: DiffTransform,
3444    ) {
3445        if let DiffTransform::BufferContent {
3446            inserted_hunk_info: inserted_hunk_anchor,
3447            summary,
3448        } = transform
3449            && self.extend_last_buffer_content_transform(
3450                new_transforms,
3451                inserted_hunk_anchor,
3452                summary,
3453            )
3454        {
3455            return;
3456        }
3457        new_transforms.push(transform, ());
3458    }
3459
3460    fn push_buffer_content_transform(
3461        &self,
3462        old_snapshot: &MultiBufferSnapshot,
3463        new_transforms: &mut SumTree<DiffTransform>,
3464        end_offset: ExcerptOffset,
3465        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3466    ) {
3467        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3468            (end_offset.min(insertion_end_offset), Some(hunk_info))
3469        });
3470        let unchanged_region = [(end_offset, None)];
3471
3472        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3473        {
3474            let start_offset = new_transforms.summary().excerpt_len();
3475            if end_offset <= start_offset {
3476                continue;
3477            }
3478            let summary_to_add = old_snapshot
3479                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3480
3481            if !self.extend_last_buffer_content_transform(
3482                new_transforms,
3483                inserted_hunk_info,
3484                summary_to_add,
3485            ) {
3486                new_transforms.push(
3487                    DiffTransform::BufferContent {
3488                        summary: summary_to_add,
3489                        inserted_hunk_info,
3490                    },
3491                    (),
3492                )
3493            }
3494        }
3495    }
3496
3497    fn extend_last_buffer_content_transform(
3498        &self,
3499        new_transforms: &mut SumTree<DiffTransform>,
3500        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3501        summary_to_add: TextSummary,
3502    ) -> bool {
3503        let mut did_extend = false;
3504        new_transforms.update_last(
3505            |last_transform| {
3506                if let DiffTransform::BufferContent {
3507                    summary,
3508                    inserted_hunk_info: inserted_hunk_anchor,
3509                } = last_transform
3510                    && *inserted_hunk_anchor == new_inserted_hunk_info
3511                {
3512                    *summary += summary_to_add;
3513                    did_extend = true;
3514                }
3515            },
3516            (),
3517        );
3518        did_extend
3519    }
3520}
3521
3522fn build_excerpt_ranges(
3523    ranges: impl IntoIterator<Item = Range<Point>>,
3524    context_line_count: u32,
3525    buffer_snapshot: &BufferSnapshot,
3526) -> Vec<ExcerptRange<Point>> {
3527    ranges
3528        .into_iter()
3529        .map(|range| {
3530            let start_row = range.start.row.saturating_sub(context_line_count);
3531            let start = Point::new(start_row, 0);
3532            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3533            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3534            ExcerptRange {
3535                context: start..end,
3536                primary: range,
3537            }
3538        })
3539        .collect()
3540}
3541
3542#[cfg(any(test, feature = "test-support"))]
3543impl MultiBuffer {
3544    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3545        let buffer = cx.new(|cx| Buffer::local(text, cx));
3546        cx.new(|cx| Self::singleton(buffer, cx))
3547    }
3548
3549    pub fn build_multi<const COUNT: usize>(
3550        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3551        cx: &mut gpui::App,
3552    ) -> Entity<Self> {
3553        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3554        for (text, ranges) in excerpts {
3555            let buffer = cx.new(|cx| Buffer::local(text, cx));
3556            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3557            multi.update(cx, |multi, cx| {
3558                multi.push_excerpts(buffer, excerpt_ranges, cx)
3559            });
3560        }
3561
3562        multi
3563    }
3564
3565    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3566        cx.new(|cx| Self::singleton(buffer, cx))
3567    }
3568
3569    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3570        cx.new(|cx| {
3571            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3572            let mutation_count = rng.random_range(1..=5);
3573            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3574            multibuffer
3575        })
3576    }
3577
3578    pub fn randomly_edit(
3579        &mut self,
3580        rng: &mut impl rand::Rng,
3581        edit_count: usize,
3582        cx: &mut Context<Self>,
3583    ) {
3584        use util::RandomCharIter;
3585
3586        let snapshot = self.read(cx);
3587        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3588        let mut last_end = None;
3589        for _ in 0..edit_count {
3590            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3591                break;
3592            }
3593
3594            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3595            let end =
3596                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3597            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3598            last_end = Some(end);
3599
3600            let mut range = start..end;
3601            if rng.random_bool(0.2) {
3602                mem::swap(&mut range.start, &mut range.end);
3603            }
3604
3605            let new_text_len = rng.random_range(0..10);
3606            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3607
3608            edits.push((range, new_text.into()));
3609        }
3610        log::info!("mutating multi-buffer with {:?}", edits);
3611        drop(snapshot);
3612
3613        self.edit(edits, None, cx);
3614    }
3615
3616    pub fn randomly_edit_excerpts(
3617        &mut self,
3618        rng: &mut impl rand::Rng,
3619        mutation_count: usize,
3620        cx: &mut Context<Self>,
3621    ) {
3622        use rand::prelude::*;
3623        use std::env;
3624        use util::RandomCharIter;
3625
3626        let max_excerpts = env::var("MAX_EXCERPTS")
3627            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3628            .unwrap_or(5);
3629
3630        let mut buffers = Vec::new();
3631        for _ in 0..mutation_count {
3632            if rng.random_bool(0.05) {
3633                log::info!("Clearing multi-buffer");
3634                self.clear(cx);
3635                continue;
3636            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3637                let ids = self.excerpt_ids();
3638                let mut excerpts = HashSet::default();
3639                for _ in 0..rng.random_range(0..ids.len()) {
3640                    excerpts.extend(ids.choose(rng).copied());
3641                }
3642
3643                let line_count = rng.random_range(0..5);
3644
3645                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3646
3647                self.expand_excerpts(
3648                    excerpts.iter().cloned(),
3649                    line_count,
3650                    ExpandExcerptDirection::UpAndDown,
3651                    cx,
3652                );
3653                continue;
3654            }
3655
3656            let excerpt_ids = self.excerpt_ids();
3657            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3658                let buffer_handle = if rng.random() || self.buffers.borrow().is_empty() {
3659                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3660                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3661                    let buffer = buffers.last().unwrap().read(cx);
3662                    log::info!(
3663                        "Creating new buffer {} with text: {:?}",
3664                        buffer.remote_id(),
3665                        buffer.text()
3666                    );
3667                    buffers.last().unwrap().clone()
3668                } else {
3669                    self.buffers
3670                        .borrow()
3671                        .values()
3672                        .choose(rng)
3673                        .unwrap()
3674                        .buffer
3675                        .clone()
3676                };
3677
3678                let buffer = buffer_handle.read(cx);
3679                let buffer_text = buffer.text();
3680                let ranges = (0..rng.random_range(0..5))
3681                    .map(|_| {
3682                        let end_ix =
3683                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3684                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3685                        ExcerptRange::new(start_ix..end_ix)
3686                    })
3687                    .collect::<Vec<_>>();
3688                log::info!(
3689                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3690                    buffer_handle.read(cx).remote_id(),
3691                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3692                    ranges
3693                        .iter()
3694                        .map(|r| &buffer_text[r.context.clone()])
3695                        .collect::<Vec<_>>()
3696                );
3697
3698                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3699                log::info!("Inserted with ids: {:?}", excerpt_id);
3700            } else {
3701                let remove_count = rng.random_range(1..=excerpt_ids.len());
3702                let mut excerpts_to_remove = excerpt_ids
3703                    .choose_multiple(rng, remove_count)
3704                    .cloned()
3705                    .collect::<Vec<_>>();
3706                let snapshot = self.snapshot.borrow();
3707                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3708                drop(snapshot);
3709                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3710                self.remove_excerpts(excerpts_to_remove, cx);
3711            }
3712        }
3713    }
3714
3715    pub fn randomly_mutate(
3716        &mut self,
3717        rng: &mut impl rand::Rng,
3718        mutation_count: usize,
3719        cx: &mut Context<Self>,
3720    ) {
3721        use rand::prelude::*;
3722
3723        if rng.random_bool(0.7) || self.singleton {
3724            let buffer = self
3725                .buffers
3726                .borrow()
3727                .values()
3728                .choose(rng)
3729                .map(|state| state.buffer.clone());
3730
3731            if let Some(buffer) = buffer {
3732                buffer.update(cx, |buffer, cx| {
3733                    if rng.random() {
3734                        buffer.randomly_edit(rng, mutation_count, cx);
3735                    } else {
3736                        buffer.randomly_undo_redo(rng, cx);
3737                    }
3738                });
3739            } else {
3740                self.randomly_edit(rng, mutation_count, cx);
3741            }
3742        } else {
3743            self.randomly_edit_excerpts(rng, mutation_count, cx);
3744        }
3745
3746        self.check_invariants(cx);
3747    }
3748
3749    fn check_invariants(&self, cx: &App) {
3750        self.read(cx).check_invariants();
3751    }
3752}
3753
3754impl EventEmitter<Event> for MultiBuffer {}
3755
3756impl MultiBufferSnapshot {
3757    pub fn text(&self) -> String {
3758        self.chunks(0..self.len(), false)
3759            .map(|chunk| chunk.text)
3760            .collect()
3761    }
3762
3763    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3764        self.reversed_chunks_in_range(0..position.to_offset(self))
3765            .flat_map(|c| c.chars().rev())
3766    }
3767
3768    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3769        let mut cursor = self.cursor::<usize>();
3770        cursor.seek(&range.end);
3771        let current_chunks = cursor.region().as_ref().map(|region| {
3772            let start_overshoot = range.start.saturating_sub(region.range.start);
3773            let end_overshoot = range.end - region.range.start;
3774            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3775            let start = region.buffer_range.start + start_overshoot;
3776            region.buffer.reversed_chunks_in_range(start..end)
3777        });
3778        ReversedMultiBufferChunks {
3779            cursor,
3780            current_chunks,
3781            start: range.start,
3782            offset: range.end,
3783        }
3784    }
3785
3786    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3787        let offset = position.to_offset(self);
3788        self.text_for_range(offset..self.len())
3789            .flat_map(|chunk| chunk.chars())
3790    }
3791
3792    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3793        self.chunks(range, false).map(|chunk| chunk.text)
3794    }
3795
3796    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3797        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3798            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3799    }
3800
3801    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3802    where
3803        T: ToOffset,
3804    {
3805        let position = position.to_offset(self);
3806        position == self.clip_offset(position, Bias::Left)
3807            && self
3808                .bytes_in_range(position..self.len())
3809                .flatten()
3810                .copied()
3811                .take(needle.len())
3812                .eq(needle.bytes())
3813    }
3814
3815    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3816        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3817    }
3818
3819    pub fn diff_hunks_in_range<T: ToPoint>(
3820        &self,
3821        range: Range<T>,
3822    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3823        let query_range = range.start.to_point(self)..range.end.to_point(self);
3824        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3825            let diff = self.diffs.get(&buffer.remote_id())?;
3826            let buffer_start = buffer.anchor_before(buffer_range.start);
3827            let buffer_end = buffer.anchor_after(buffer_range.end);
3828            Some(
3829                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3830                    .filter_map(|hunk| {
3831                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3832                            return None;
3833                        }
3834                        Some((hunk.range.clone(), hunk))
3835                    }),
3836            )
3837        })
3838        .filter_map(move |(range, hunk, excerpt)| {
3839            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3840            {
3841                return None;
3842            }
3843            let end_row = if range.end.column == 0 {
3844                range.end.row
3845            } else {
3846                range.end.row + 1
3847            };
3848            Some(MultiBufferDiffHunk {
3849                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3850                buffer_id: excerpt.buffer_id,
3851                excerpt_id: excerpt.id,
3852                buffer_range: hunk.buffer_range.clone(),
3853                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3854                secondary_status: hunk.secondary_status,
3855            })
3856        })
3857    }
3858
3859    pub fn excerpt_ids_for_range<T: ToOffset>(
3860        &self,
3861        range: Range<T>,
3862    ) -> impl Iterator<Item = ExcerptId> + '_ {
3863        let range = range.start.to_offset(self)..range.end.to_offset(self);
3864        let mut cursor = self.cursor::<usize>();
3865        cursor.seek(&range.start);
3866        std::iter::from_fn(move || {
3867            let region = cursor.region()?;
3868            if region.range.start >= range.end {
3869                return None;
3870            }
3871            cursor.next_excerpt();
3872            Some(region.excerpt.id)
3873        })
3874    }
3875
3876    pub fn buffer_ids_for_range<T: ToOffset>(
3877        &self,
3878        range: Range<T>,
3879    ) -> impl Iterator<Item = BufferId> + '_ {
3880        let range = range.start.to_offset(self)..range.end.to_offset(self);
3881        let mut cursor = self.cursor::<usize>();
3882        cursor.seek(&range.start);
3883        std::iter::from_fn(move || {
3884            let region = cursor.region()?;
3885            if region.range.start > range.end
3886                || region.range.start == range.end && region.range.start > range.start
3887            {
3888                return None;
3889            }
3890            cursor.next_excerpt();
3891            Some(region.excerpt.buffer_id)
3892        })
3893    }
3894
3895    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3896        &self,
3897        ranges: impl Iterator<Item = Range<T>>,
3898    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3899        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3900    }
3901
3902    pub fn range_to_buffer_ranges<T: ToOffset>(
3903        &self,
3904        range: Range<T>,
3905    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3906        let start = range.start.to_offset(self);
3907        let end = range.end.to_offset(self);
3908
3909        let mut cursor = self.cursor::<usize>();
3910        cursor.seek(&start);
3911
3912        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3913        while let Some(region) = cursor.region() {
3914            if region.range.start > end {
3915                break;
3916            }
3917            if region.is_main_buffer {
3918                let start_overshoot = start.saturating_sub(region.range.start);
3919                let end_overshoot = end.saturating_sub(region.range.start);
3920                let start = region
3921                    .buffer_range
3922                    .end
3923                    .min(region.buffer_range.start + start_overshoot);
3924                let end = region
3925                    .buffer_range
3926                    .end
3927                    .min(region.buffer_range.start + end_overshoot);
3928                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3929                    *excerpt_id == region.excerpt.id && prev_range.end == start
3930                }) {
3931                    prev.1.end = end;
3932                } else {
3933                    result.push((region.buffer, start..end, region.excerpt.id));
3934                }
3935            }
3936            cursor.next();
3937        }
3938        result
3939    }
3940
3941    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3942        &self,
3943        range: Range<T>,
3944    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3945        let start = range.start.to_offset(self);
3946        let end = range.end.to_offset(self);
3947
3948        let mut cursor = self.cursor::<usize>();
3949        cursor.seek(&start);
3950
3951        std::iter::from_fn(move || {
3952            let region = cursor.region()?;
3953            if region.range.start > end {
3954                return None;
3955            }
3956            let start_overshoot = start.saturating_sub(region.range.start);
3957            let end_overshoot = end.saturating_sub(region.range.start);
3958            let start = region
3959                .buffer_range
3960                .end
3961                .min(region.buffer_range.start + start_overshoot);
3962            let end = region
3963                .buffer_range
3964                .end
3965                .min(region.buffer_range.start + end_overshoot);
3966
3967            let region_excerpt_id = region.excerpt.id;
3968            let deleted_hunk_anchor = if region.is_main_buffer {
3969                None
3970            } else {
3971                Some(self.anchor_before(region.range.start))
3972            };
3973            let result = (
3974                region.buffer,
3975                start..end,
3976                region_excerpt_id,
3977                deleted_hunk_anchor,
3978            );
3979            cursor.next();
3980            Some(result)
3981        })
3982    }
3983
3984    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3985    /// coordinates.
3986    ///
3987    /// The given callback will be called for every excerpt intersecting the given range. It will
3988    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3989    /// The callback should return an iterator of metadata items from that buffer, each paired
3990    /// with a buffer range.
3991    ///
3992    /// The returned iterator yields each of these metadata items, paired with its range in
3993    /// multi-buffer coordinates.
3994    fn lift_buffer_metadata<'a, D, M, I>(
3995        &'a self,
3996        query_range: Range<D>,
3997        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
3998    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
3999    where
4000        I: Iterator<Item = (Range<D>, M)> + 'a,
4001        D: TextDimension + Ord + Sub<D, Output = D>,
4002    {
4003        let max_position = D::from_text_summary(&self.text_summary());
4004        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4005        let mut cursor = self.cursor::<D>();
4006
4007        // Find the excerpt and buffer offset where the given range ends.
4008        cursor.seek(&query_range.end);
4009        let mut range_end = None;
4010        while let Some(region) = cursor.region() {
4011            if region.is_main_buffer {
4012                let mut buffer_end = region.buffer_range.start;
4013                let overshoot = if query_range.end > region.range.start {
4014                    query_range.end - region.range.start
4015                } else {
4016                    D::default()
4017                };
4018                buffer_end.add_assign(&overshoot);
4019                range_end = Some((region.excerpt.id, buffer_end));
4020                break;
4021            }
4022            cursor.next();
4023        }
4024
4025        cursor.seek(&query_range.start);
4026
4027        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4028            && region.range.start > D::zero(())
4029        {
4030            cursor.prev()
4031        }
4032
4033        iter::from_fn(move || {
4034            loop {
4035                let excerpt = cursor.excerpt()?;
4036
4037                // If we have already retrieved metadata for this excerpt, continue to use it.
4038                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4039                    .as_mut()
4040                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4041                {
4042                    Some(metadata)
4043                }
4044                // Otherwise, compute the intersection of the input range with the excerpt's range,
4045                // and retrieve the metadata for the resulting range.
4046                else {
4047                    let region = cursor.region()?;
4048                    let mut buffer_start;
4049                    if region.is_main_buffer {
4050                        buffer_start = region.buffer_range.start;
4051                        if query_range.start > region.range.start {
4052                            let overshoot = query_range.start - region.range.start;
4053                            buffer_start.add_assign(&overshoot);
4054                        }
4055                        buffer_start = buffer_start.min(region.buffer_range.end);
4056                    } else {
4057                        buffer_start = cursor.main_buffer_position()?;
4058                    };
4059                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4060                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4061                        && excerpt.id == end_excerpt_id
4062                    {
4063                        buffer_end = buffer_end.min(end_buffer_offset);
4064                    }
4065
4066                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4067                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4068                    })
4069                };
4070
4071                // Visit each metadata item.
4072                if let Some((metadata_buffer_range, metadata)) =
4073                    metadata_iter.and_then(Iterator::next)
4074                {
4075                    // Find the multibuffer regions that contain the start and end of
4076                    // the metadata item's range.
4077                    if metadata_buffer_range.start > D::default() {
4078                        while let Some(region) = cursor.region() {
4079                            if region.is_main_buffer
4080                                && (region.buffer_range.end >= metadata_buffer_range.start
4081                                    || cursor.is_at_end_of_excerpt())
4082                            {
4083                                break;
4084                            }
4085                            cursor.next();
4086                        }
4087                    }
4088                    let start_region = cursor.region()?;
4089                    while let Some(region) = cursor.region() {
4090                        if region.is_main_buffer
4091                            && (region.buffer_range.end > metadata_buffer_range.end
4092                                || cursor.is_at_end_of_excerpt())
4093                        {
4094                            break;
4095                        }
4096                        cursor.next();
4097                    }
4098                    let end_region = cursor.region();
4099
4100                    // Convert the metadata item's range into multibuffer coordinates.
4101                    let mut start_position = start_region.range.start;
4102                    let region_buffer_start = start_region.buffer_range.start;
4103                    if start_region.is_main_buffer
4104                        && metadata_buffer_range.start > region_buffer_start
4105                    {
4106                        start_position
4107                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4108                        start_position = start_position.min(start_region.range.end);
4109                    }
4110
4111                    let mut end_position = max_position;
4112                    if let Some(end_region) = &end_region {
4113                        end_position = end_region.range.start;
4114                        debug_assert!(end_region.is_main_buffer);
4115                        let region_buffer_start = end_region.buffer_range.start;
4116                        if metadata_buffer_range.end > region_buffer_start {
4117                            end_position
4118                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4119                        }
4120                        end_position = end_position.min(end_region.range.end);
4121                    }
4122
4123                    if start_position <= query_range.end && end_position >= query_range.start {
4124                        return Some((start_position..end_position, metadata, excerpt));
4125                    }
4126                }
4127                // When there are no more metadata items for this excerpt, move to the next excerpt.
4128                else {
4129                    current_excerpt_metadata.take();
4130                    if let Some((end_excerpt_id, _)) = range_end
4131                        && excerpt.id == end_excerpt_id
4132                    {
4133                        return None;
4134                    }
4135                    cursor.next_excerpt();
4136                }
4137            }
4138        })
4139    }
4140
4141    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4142        let offset = position.to_offset(self);
4143
4144        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4145        cursor.seek(&DimensionPair {
4146            key: offset,
4147            value: None,
4148        });
4149        cursor.seek_to_start_of_current_excerpt();
4150        let excerpt = cursor.excerpt()?;
4151
4152        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4153        let current_position = self
4154            .anchor_before(offset)
4155            .text_anchor
4156            .to_offset(&excerpt.buffer);
4157        let excerpt_end = excerpt
4158            .buffer
4159            .anchor_before(excerpt_end.min(current_position));
4160
4161        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4162            for hunk in diff.hunks_intersecting_range_rev(
4163                excerpt.range.context.start..excerpt_end,
4164                &excerpt.buffer,
4165            ) {
4166                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4167                if hunk_end >= current_position {
4168                    continue;
4169                }
4170                let start =
4171                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4172                        .to_point(self);
4173                return Some(MultiBufferRow(start.row));
4174            }
4175        }
4176
4177        loop {
4178            cursor.prev_excerpt();
4179            let excerpt = cursor.excerpt()?;
4180
4181            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4182                continue;
4183            };
4184            let mut hunks =
4185                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4186            let Some(hunk) = hunks.next() else {
4187                continue;
4188            };
4189            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4190                .to_point(self);
4191            return Some(MultiBufferRow(start.row));
4192        }
4193    }
4194
4195    pub fn has_diff_hunks(&self) -> bool {
4196        self.diffs.values().any(|diff| !diff.is_empty())
4197    }
4198
4199    pub fn is_inside_word<T: ToOffset>(
4200        &self,
4201        position: T,
4202        scope_context: Option<CharScopeContext>,
4203    ) -> bool {
4204        let position = position.to_offset(self);
4205        let classifier = self
4206            .char_classifier_at(position)
4207            .scope_context(scope_context);
4208        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4209        let prev_char_kind = self
4210            .reversed_chars_at(position)
4211            .next()
4212            .map(|c| classifier.kind(c));
4213        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4214    }
4215
4216    pub fn surrounding_word<T: ToOffset>(
4217        &self,
4218        start: T,
4219        scope_context: Option<CharScopeContext>,
4220    ) -> (Range<usize>, Option<CharKind>) {
4221        let mut start = start.to_offset(self);
4222        let mut end = start;
4223        let mut next_chars = self.chars_at(start).peekable();
4224        let mut prev_chars = self.reversed_chars_at(start).peekable();
4225
4226        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4227
4228        let word_kind = cmp::max(
4229            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4230            next_chars.peek().copied().map(|c| classifier.kind(c)),
4231        );
4232
4233        for ch in prev_chars {
4234            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4235                start -= ch.len_utf8();
4236            } else {
4237                break;
4238            }
4239        }
4240
4241        for ch in next_chars {
4242            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4243                end += ch.len_utf8();
4244            } else {
4245                break;
4246            }
4247        }
4248
4249        (start..end, word_kind)
4250    }
4251
4252    pub fn char_kind_before<T: ToOffset>(
4253        &self,
4254        start: T,
4255        scope_context: Option<CharScopeContext>,
4256    ) -> Option<CharKind> {
4257        let start = start.to_offset(self);
4258        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4259        self.reversed_chars_at(start)
4260            .next()
4261            .map(|ch| classifier.kind(ch))
4262    }
4263
4264    pub fn is_singleton(&self) -> bool {
4265        self.singleton
4266    }
4267
4268    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4269        if self.singleton {
4270            self.excerpts
4271                .iter()
4272                .next()
4273                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4274        } else {
4275            None
4276        }
4277    }
4278
4279    pub fn len(&self) -> usize {
4280        self.diff_transforms.summary().output.len
4281    }
4282
4283    pub fn is_empty(&self) -> bool {
4284        self.excerpts.summary().text.len == 0
4285    }
4286
4287    pub fn widest_line_number(&self) -> u32 {
4288        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4289        self.excerpts.summary().widest_line_number + 1
4290    }
4291
4292    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4293        let range = range.start.to_offset(self)..range.end.to_offset(self);
4294        let mut excerpts = self.cursor::<usize>();
4295        excerpts.seek(&range.start);
4296
4297        let mut chunk;
4298        let mut has_trailing_newline;
4299        let excerpt_bytes;
4300        if let Some(region) = excerpts.region() {
4301            let mut bytes = region.buffer.bytes_in_range(
4302                region.buffer_range.start + range.start - region.range.start
4303                    ..(region.buffer_range.start + range.end - region.range.start)
4304                        .min(region.buffer_range.end),
4305            );
4306            chunk = bytes.next().unwrap_or(&[][..]);
4307            excerpt_bytes = Some(bytes);
4308            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4309            if chunk.is_empty() && has_trailing_newline {
4310                chunk = b"\n";
4311                has_trailing_newline = false;
4312            }
4313        } else {
4314            chunk = &[][..];
4315            excerpt_bytes = None;
4316            has_trailing_newline = false;
4317        };
4318
4319        MultiBufferBytes {
4320            range,
4321            cursor: excerpts,
4322            excerpt_bytes,
4323            has_trailing_newline,
4324            chunk,
4325        }
4326    }
4327
4328    pub fn reversed_bytes_in_range<T: ToOffset>(
4329        &self,
4330        range: Range<T>,
4331    ) -> ReversedMultiBufferBytes<'_> {
4332        let range = range.start.to_offset(self)..range.end.to_offset(self);
4333        let mut chunks = self.reversed_chunks_in_range(range.clone());
4334        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4335        ReversedMultiBufferBytes {
4336            range,
4337            chunks,
4338            chunk,
4339        }
4340    }
4341
4342    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4343        let mut cursor = self.cursor::<Point>();
4344        cursor.seek(&Point::new(start_row.0, 0));
4345        let mut result = MultiBufferRows {
4346            point: Point::new(0, 0),
4347            is_empty: self.excerpts.is_empty(),
4348            is_singleton: self.is_singleton(),
4349            cursor,
4350        };
4351        result.seek(start_row);
4352        result
4353    }
4354
4355    pub fn chunks<T: ToOffset>(
4356        &self,
4357        range: Range<T>,
4358        language_aware: bool,
4359    ) -> MultiBufferChunks<'_> {
4360        let mut chunks = MultiBufferChunks {
4361            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4362            range: 0..0,
4363            excerpts: self.excerpts.cursor(()),
4364            diff_transforms: self.diff_transforms.cursor(()),
4365            diffs: &self.diffs,
4366            diff_base_chunks: None,
4367            excerpt_chunks: None,
4368            buffer_chunk: None,
4369            language_aware,
4370        };
4371        let range = range.start.to_offset(self)..range.end.to_offset(self);
4372        chunks.seek(range);
4373        chunks
4374    }
4375
4376    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4377        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4378    }
4379
4380    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4381        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4382    }
4383
4384    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4385        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4386    }
4387
4388    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4389        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4390            buffer.clip_point_utf16(Unclipped(point), bias)
4391        })
4392    }
4393
4394    pub fn offset_to_point(&self, offset: usize) -> Point {
4395        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4396    }
4397
4398    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4399        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4400    }
4401
4402    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4403        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4404    }
4405
4406    pub fn point_to_offset(&self, point: Point) -> usize {
4407        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4408    }
4409
4410    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4411        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4412    }
4413
4414    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4415        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4416    }
4417
4418    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4419        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4420    }
4421
4422    fn clip_dimension<D>(
4423        &self,
4424        position: D,
4425        bias: Bias,
4426        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4427    ) -> D
4428    where
4429        D: TextDimension + Ord + Sub<D, Output = D>,
4430    {
4431        let mut cursor = self.cursor();
4432        cursor.seek(&position);
4433        if let Some(region) = cursor.region() {
4434            if position >= region.range.end {
4435                return region.range.end;
4436            }
4437            let overshoot = position - region.range.start;
4438            let mut buffer_position = region.buffer_range.start;
4439            buffer_position.add_assign(&overshoot);
4440            let clipped_buffer_position =
4441                clip_buffer_position(region.buffer, buffer_position, bias);
4442            let mut position = region.range.start;
4443            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4444            position
4445        } else {
4446            D::from_text_summary(&self.text_summary())
4447        }
4448    }
4449
4450    fn convert_dimension<D1, D2>(
4451        &self,
4452        key: D1,
4453        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4454    ) -> D2
4455    where
4456        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4457        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4458    {
4459        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4460        cursor.seek(&DimensionPair { key, value: None });
4461        if let Some(region) = cursor.region() {
4462            if key >= region.range.end.key {
4463                return region.range.end.value.unwrap();
4464            }
4465            let start_key = region.range.start.key;
4466            let start_value = region.range.start.value.unwrap();
4467            let buffer_start_key = region.buffer_range.start.key;
4468            let buffer_start_value = region.buffer_range.start.value.unwrap();
4469            let mut buffer_key = buffer_start_key;
4470            buffer_key.add_assign(&(key - start_key));
4471            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4472            let mut result = start_value;
4473            result.add_assign(&(buffer_value - buffer_start_value));
4474            result
4475        } else {
4476            D2::from_text_summary(&self.text_summary())
4477        }
4478    }
4479
4480    pub fn point_to_buffer_offset<T: ToOffset>(
4481        &self,
4482        point: T,
4483    ) -> Option<(&BufferSnapshot, usize)> {
4484        let offset = point.to_offset(self);
4485        let mut cursor = self.cursor::<usize>();
4486        cursor.seek(&offset);
4487        let region = cursor.region()?;
4488        let overshoot = offset - region.range.start;
4489        let buffer_offset = region.buffer_range.start + overshoot;
4490        if buffer_offset == region.buffer.len() + 1
4491            && region.has_trailing_newline
4492            && !region.is_main_buffer
4493        {
4494            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4495        } else if buffer_offset > region.buffer.len() {
4496            return None;
4497        }
4498        Some((region.buffer, buffer_offset))
4499    }
4500
4501    pub fn point_to_buffer_point(
4502        &self,
4503        point: Point,
4504    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4505        let mut cursor = self.cursor::<Point>();
4506        cursor.seek(&point);
4507        let region = cursor.region()?;
4508        let overshoot = point - region.range.start;
4509        let buffer_point = region.buffer_range.start + overshoot;
4510        let excerpt = cursor.excerpt()?;
4511        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4512            && region.has_trailing_newline
4513            && !region.is_main_buffer
4514        {
4515            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4516        } else if buffer_point > region.buffer.max_point() {
4517            return None;
4518        }
4519        Some((region.buffer, buffer_point, excerpt.id))
4520    }
4521
4522    pub fn suggested_indents(
4523        &self,
4524        rows: impl IntoIterator<Item = u32>,
4525        cx: &App,
4526    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4527        let mut result = BTreeMap::new();
4528
4529        let mut rows_for_excerpt = Vec::new();
4530        let mut cursor = self.cursor::<Point>();
4531        let mut rows = rows.into_iter().peekable();
4532        let mut prev_row = u32::MAX;
4533        let mut prev_language_indent_size = IndentSize::default();
4534
4535        while let Some(row) = rows.next() {
4536            cursor.seek(&Point::new(row, 0));
4537            let Some(region) = cursor.region() else {
4538                continue;
4539            };
4540
4541            // Retrieve the language and indent size once for each disjoint region being indented.
4542            let single_indent_size = if row.saturating_sub(1) == prev_row {
4543                prev_language_indent_size
4544            } else {
4545                region
4546                    .buffer
4547                    .language_indent_size_at(Point::new(row, 0), cx)
4548            };
4549            prev_language_indent_size = single_indent_size;
4550            prev_row = row;
4551
4552            let start_buffer_row = region.buffer_range.start.row;
4553            let start_multibuffer_row = region.range.start.row;
4554            let end_multibuffer_row = region.range.end.row;
4555
4556            rows_for_excerpt.push(row);
4557            while let Some(next_row) = rows.peek().copied() {
4558                if end_multibuffer_row > next_row {
4559                    rows_for_excerpt.push(next_row);
4560                    rows.next();
4561                } else {
4562                    break;
4563                }
4564            }
4565
4566            let buffer_rows = rows_for_excerpt
4567                .drain(..)
4568                .map(|row| start_buffer_row + row - start_multibuffer_row);
4569            let buffer_indents = region
4570                .buffer
4571                .suggested_indents(buffer_rows, single_indent_size);
4572            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4573                (
4574                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4575                    indent,
4576                )
4577            });
4578            result.extend(multibuffer_indents);
4579        }
4580
4581        result
4582    }
4583
4584    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4585        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4586            let mut size = buffer.indent_size_for_line(range.start.row);
4587            size.len = size
4588                .len
4589                .min(range.end.column)
4590                .saturating_sub(range.start.column);
4591            size
4592        } else {
4593            IndentSize::spaces(0)
4594        }
4595    }
4596
4597    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4598        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4599            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4600        } else {
4601            LineIndent::spaces(0)
4602        }
4603    }
4604
4605    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4606        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4607
4608        if self.language_settings(cx).extend_comment_on_newline
4609            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4610        {
4611            let delimiters = language_scope.line_comment_prefixes();
4612            for delimiter in delimiters {
4613                if *self
4614                    .chars_at(Point::new(row.0, indent.len() as u32))
4615                    .take(delimiter.chars().count())
4616                    .collect::<String>()
4617                    .as_str()
4618                    == **delimiter
4619                {
4620                    indent.push_str(delimiter);
4621                    break;
4622                }
4623            }
4624        }
4625
4626        indent
4627    }
4628
4629    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4630    where
4631        T: ToOffset,
4632    {
4633        for char in self.reversed_chars_at(position) {
4634            if !char.is_whitespace() {
4635                return false;
4636            }
4637            if char == '\n' {
4638                return true;
4639            }
4640        }
4641        true
4642    }
4643
4644    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4645        while row.0 > 0 {
4646            row.0 -= 1;
4647            if !self.is_line_blank(row) {
4648                return Some(row);
4649            }
4650        }
4651        None
4652    }
4653
4654    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4655        if let Some((_, range)) = self.buffer_line_for_row(row) {
4656            range.end.column - range.start.column
4657        } else {
4658            0
4659        }
4660    }
4661
4662    pub fn buffer_line_for_row(
4663        &self,
4664        row: MultiBufferRow,
4665    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4666        let mut cursor = self.cursor::<Point>();
4667        let point = Point::new(row.0, 0);
4668        cursor.seek(&point);
4669        let region = cursor.region()?;
4670        let overshoot = point.min(region.range.end) - region.range.start;
4671        let buffer_point = region.buffer_range.start + overshoot;
4672        if buffer_point.row > region.buffer_range.end.row {
4673            return None;
4674        }
4675        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4676        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4677            .min(region.buffer_range.end);
4678        Some((region.buffer, line_start..line_end))
4679    }
4680
4681    pub fn max_point(&self) -> Point {
4682        self.text_summary().lines
4683    }
4684
4685    pub fn max_row(&self) -> MultiBufferRow {
4686        MultiBufferRow(self.text_summary().lines.row)
4687    }
4688
4689    pub fn text_summary(&self) -> TextSummary {
4690        self.diff_transforms.summary().output
4691    }
4692
4693    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4694    where
4695        D: TextDimension,
4696        O: ToOffset,
4697    {
4698        let range = range.start.to_offset(self)..range.end.to_offset(self);
4699        let mut cursor = self
4700            .diff_transforms
4701            .cursor::<Dimensions<usize, ExcerptOffset>>(());
4702        cursor.seek(&range.start, Bias::Right);
4703
4704        let Some(first_transform) = cursor.item() else {
4705            return D::from_text_summary(&TextSummary::default());
4706        };
4707
4708        let diff_transform_start = cursor.start().0;
4709        let diff_transform_end = cursor.end().0;
4710        let diff_start = range.start;
4711        let start_overshoot = diff_start - diff_transform_start;
4712        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4713
4714        let mut result = match first_transform {
4715            DiffTransform::BufferContent { .. } => {
4716                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4717                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4718                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4719            }
4720            DiffTransform::DeletedHunk {
4721                buffer_id,
4722                base_text_byte_range,
4723                has_trailing_newline,
4724                ..
4725            } => {
4726                let buffer_start = base_text_byte_range.start + start_overshoot;
4727                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4728                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4729                    panic!("{:?} is in non-existent deleted hunk", range.start)
4730                };
4731
4732                let include_trailing_newline =
4733                    *has_trailing_newline && range.end >= diff_transform_end;
4734                if include_trailing_newline {
4735                    buffer_end -= 1;
4736                }
4737
4738                let mut summary =
4739                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4740
4741                if include_trailing_newline {
4742                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4743                }
4744
4745                summary
4746            }
4747        };
4748        if range.end < diff_transform_end {
4749            return result;
4750        }
4751
4752        cursor.next();
4753        result.add_assign(&D::from_text_summary(
4754            &cursor.summary(&range.end, Bias::Right),
4755        ));
4756
4757        let Some(last_transform) = cursor.item() else {
4758            return result;
4759        };
4760
4761        let overshoot = range.end - cursor.start().0;
4762        let suffix = match last_transform {
4763            DiffTransform::BufferContent { .. } => {
4764                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4765                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4766            }
4767            DiffTransform::DeletedHunk {
4768                base_text_byte_range,
4769                buffer_id,
4770                has_trailing_newline,
4771                ..
4772            } => {
4773                let buffer_end = base_text_byte_range.start + overshoot;
4774                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4775                    panic!("{:?} is in non-existent deleted hunk", range.end)
4776                };
4777
4778                let mut suffix = base_text
4779                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4780                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4781                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4782                }
4783                suffix
4784            }
4785        };
4786
4787        result.add_assign(&suffix);
4788        result
4789    }
4790
4791    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4792    where
4793        D: TextDimension,
4794    {
4795        let mut summary = D::zero(());
4796        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
4797        cursor.seek(&range.start, Bias::Right);
4798        if let Some(excerpt) = cursor.item() {
4799            let mut end_before_newline = cursor.end();
4800            if excerpt.has_trailing_newline {
4801                end_before_newline -= ExcerptOffset::new(1);
4802            }
4803
4804            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4805            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4806            let end_in_excerpt =
4807                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4808            summary.add_assign(
4809                &excerpt
4810                    .buffer
4811                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4812            );
4813
4814            if range.end > end_before_newline {
4815                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4816            }
4817
4818            cursor.next();
4819        }
4820
4821        if range.end > *cursor.start() {
4822            summary.add_assign(
4823                &cursor
4824                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right)
4825                    .0,
4826            );
4827            if let Some(excerpt) = cursor.item() {
4828                range.end = cmp::max(*cursor.start(), range.end);
4829
4830                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4831                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4832                summary.add_assign(
4833                    &excerpt
4834                        .buffer
4835                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4836                );
4837            }
4838        }
4839
4840        summary
4841    }
4842
4843    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4844    where
4845        D: TextDimension + Ord + Sub<D, Output = D>,
4846    {
4847        self.summaries_for_anchors([anchor])[0]
4848    }
4849
4850    fn resolve_summary_for_anchor<D>(
4851        &self,
4852        anchor: &Anchor,
4853        excerpt_position: D,
4854        diff_transforms: &mut Cursor<
4855            DiffTransform,
4856            Dimensions<ExcerptDimension<D>, OutputDimension<D>>,
4857        >,
4858    ) -> D
4859    where
4860        D: TextDimension + Ord + Sub<D, Output = D>,
4861    {
4862        loop {
4863            let transform_end_position = diff_transforms.end().0.0;
4864            let at_transform_end =
4865                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4866            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4867                diff_transforms.next();
4868                continue;
4869            }
4870
4871            let mut position = diff_transforms.start().1.0;
4872            match diff_transforms.item() {
4873                Some(DiffTransform::DeletedHunk {
4874                    buffer_id,
4875                    base_text_byte_range,
4876                    ..
4877                }) => {
4878                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
4879                        && let Some(base_text) =
4880                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4881                        && base_text.can_resolve(diff_base_anchor)
4882                    {
4883                        let base_text_offset = diff_base_anchor.to_offset(base_text);
4884                        if base_text_offset >= base_text_byte_range.start
4885                            && base_text_offset <= base_text_byte_range.end
4886                        {
4887                            let position_in_hunk = base_text.text_summary_for_range::<D, _>(
4888                                base_text_byte_range.start..base_text_offset,
4889                            );
4890                            position.add_assign(&position_in_hunk);
4891                        } else if at_transform_end {
4892                            diff_transforms.next();
4893                            continue;
4894                        }
4895                    }
4896                }
4897                _ => {
4898                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4899                        diff_transforms.next();
4900                        continue;
4901                    }
4902                    let overshoot = excerpt_position - diff_transforms.start().0.0;
4903                    position.add_assign(&overshoot);
4904                }
4905            }
4906
4907            return position;
4908        }
4909    }
4910
4911    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4912        let mut cursor = self
4913            .excerpts
4914            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
4915        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4916
4917        cursor.seek(&Some(locator), Bias::Left);
4918        if cursor.item().is_none() && anchor.excerpt_id == ExcerptId::max() {
4919            cursor.prev();
4920        }
4921
4922        let mut position = cursor.start().1;
4923        if let Some(excerpt) = cursor.item()
4924            && (excerpt.id == anchor.excerpt_id || anchor.excerpt_id == ExcerptId::max())
4925        {
4926            let excerpt_buffer_start = excerpt
4927                .buffer
4928                .offset_for_anchor(&excerpt.range.context.start);
4929            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4930            let buffer_position = cmp::min(
4931                excerpt_buffer_end,
4932                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4933            );
4934            if buffer_position > excerpt_buffer_start {
4935                position.value += buffer_position - excerpt_buffer_start;
4936            }
4937        }
4938        position
4939    }
4940
4941    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
4942        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
4943            excerpt_id = *replacement;
4944        }
4945        excerpt_id
4946    }
4947
4948    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4949    where
4950        D: TextDimension + Ord + Sub<D, Output = D>,
4951        I: 'a + IntoIterator<Item = &'a Anchor>,
4952    {
4953        let mut anchors = anchors.into_iter().peekable();
4954        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
4955        let mut diff_transforms_cursor = self
4956            .diff_transforms
4957            .cursor::<Dimensions<ExcerptDimension<D>, OutputDimension<D>>>(());
4958        diff_transforms_cursor.next();
4959
4960        let mut summaries = Vec::new();
4961        while let Some(anchor) = anchors.peek() {
4962            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
4963
4964            let excerpt_anchors = anchors.peeking_take_while(|anchor| {
4965                self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id
4966            });
4967
4968            let locator = self.excerpt_locator_for_id(excerpt_id);
4969            cursor.seek_forward(locator, Bias::Left);
4970            if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
4971                cursor.prev();
4972            }
4973
4974            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4975            if let Some(excerpt) = cursor.item() {
4976                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
4977                    let position = self.resolve_summary_for_anchor(
4978                        &Anchor::min(),
4979                        excerpt_start_position,
4980                        &mut diff_transforms_cursor,
4981                    );
4982                    summaries.extend(excerpt_anchors.map(|_| position));
4983                    continue;
4984                }
4985                let excerpt_buffer_start =
4986                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4987                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4988                for (buffer_summary, anchor) in excerpt
4989                    .buffer
4990                    .summaries_for_anchors_with_payload::<D, _, _>(
4991                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
4992                    )
4993                {
4994                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
4995                    let mut position = excerpt_start_position;
4996                    if summary > excerpt_buffer_start {
4997                        position.add_assign(&(summary - excerpt_buffer_start));
4998                    }
4999
5000                    if position > diff_transforms_cursor.start().0.0 {
5001                        diff_transforms_cursor
5002                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5003                    }
5004
5005                    summaries.push(self.resolve_summary_for_anchor(
5006                        anchor,
5007                        position,
5008                        &mut diff_transforms_cursor,
5009                    ));
5010                }
5011            } else {
5012                diff_transforms_cursor
5013                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5014                let position = self.resolve_summary_for_anchor(
5015                    &Anchor::max(),
5016                    excerpt_start_position,
5017                    &mut diff_transforms_cursor,
5018                );
5019                summaries.extend(excerpt_anchors.map(|_| position));
5020            }
5021        }
5022
5023        summaries
5024    }
5025
5026    pub fn dimensions_from_points<'a, D>(
5027        &'a self,
5028        points: impl 'a + IntoIterator<Item = Point>,
5029    ) -> impl 'a + Iterator<Item = D>
5030    where
5031        D: TextDimension + Sub<D, Output = D>,
5032    {
5033        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5034        cursor.seek(&DimensionPair {
5035            key: Point::default(),
5036            value: None,
5037        });
5038        let mut points = points.into_iter();
5039        iter::from_fn(move || {
5040            let point = points.next()?;
5041
5042            cursor.seek_forward(&DimensionPair {
5043                key: point,
5044                value: None,
5045            });
5046
5047            if let Some(region) = cursor.region() {
5048                let overshoot = point - region.range.start.key;
5049                let buffer_point = region.buffer_range.start.key + overshoot;
5050                let mut position = region.range.start.value.unwrap();
5051                position.add_assign(
5052                    &region
5053                        .buffer
5054                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5055                );
5056                if point == region.range.end.key && region.has_trailing_newline {
5057                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5058                }
5059                Some(position)
5060            } else {
5061                Some(D::from_text_summary(&self.text_summary()))
5062            }
5063        })
5064    }
5065
5066    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5067    where
5068        I: 'a + IntoIterator<Item = &'a Anchor>,
5069    {
5070        let mut anchors = anchors.into_iter().enumerate().peekable();
5071        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5072        cursor.next();
5073
5074        let mut result = Vec::new();
5075
5076        while let Some((_, anchor)) = anchors.peek() {
5077            let old_excerpt_id = anchor.excerpt_id;
5078
5079            // Find the location where this anchor's excerpt should be.
5080            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5081            cursor.seek_forward(&Some(old_locator), Bias::Left);
5082
5083            let next_excerpt = cursor.item();
5084            let prev_excerpt = cursor.prev_item();
5085
5086            // Process all of the anchors for this excerpt.
5087            while let Some((anchor_ix, &anchor)) =
5088                anchors.next_if(|(_, anchor)| anchor.excerpt_id == old_excerpt_id)
5089            {
5090                let mut anchor = anchor;
5091
5092                // Leave min and max anchors unchanged if invalid or
5093                // if the old excerpt still exists at this location
5094                let mut kept_position = next_excerpt
5095                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5096                    || old_excerpt_id == ExcerptId::max()
5097                    || old_excerpt_id == ExcerptId::min();
5098
5099                // If the old excerpt no longer exists at this location, then attempt to
5100                // find an equivalent position for this anchor in an adjacent excerpt.
5101                if !kept_position {
5102                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5103                        if excerpt.contains(&anchor) {
5104                            anchor.excerpt_id = excerpt.id;
5105                            kept_position = true;
5106                            break;
5107                        }
5108                    }
5109                }
5110
5111                // If there's no adjacent excerpt that contains the anchor's position,
5112                // then report that the anchor has lost its position.
5113                if !kept_position {
5114                    anchor = if let Some(excerpt) = next_excerpt {
5115                        let mut text_anchor = excerpt
5116                            .range
5117                            .context
5118                            .start
5119                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5120                        if text_anchor
5121                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5122                            .is_gt()
5123                        {
5124                            text_anchor = excerpt.range.context.end;
5125                        }
5126                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5127                    } else if let Some(excerpt) = prev_excerpt {
5128                        let mut text_anchor = excerpt
5129                            .range
5130                            .context
5131                            .end
5132                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5133                        if text_anchor
5134                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5135                            .is_lt()
5136                        {
5137                            text_anchor = excerpt.range.context.start;
5138                        }
5139                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5140                    } else if anchor.text_anchor.bias == Bias::Left {
5141                        Anchor::min()
5142                    } else {
5143                        Anchor::max()
5144                    };
5145                }
5146
5147                result.push((anchor_ix, anchor, kept_position));
5148            }
5149        }
5150        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5151        result
5152    }
5153
5154    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5155        self.anchor_at(position, Bias::Left)
5156    }
5157
5158    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5159        self.anchor_at(position, Bias::Right)
5160    }
5161
5162    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5163        let offset = position.to_offset(self);
5164
5165        // Find the given position in the diff transforms. Determine the corresponding
5166        // offset in the excerpts, and whether the position is within a deleted hunk.
5167        let mut diff_transforms = self
5168            .diff_transforms
5169            .cursor::<Dimensions<usize, ExcerptOffset>>(());
5170        diff_transforms.seek(&offset, Bias::Right);
5171
5172        if offset == diff_transforms.start().0
5173            && bias == Bias::Left
5174            && let Some(prev_item) = diff_transforms.prev_item()
5175            && let DiffTransform::DeletedHunk { .. } = prev_item
5176        {
5177            diff_transforms.prev();
5178        }
5179        let offset_in_transform = offset - diff_transforms.start().0;
5180        let mut excerpt_offset = diff_transforms.start().1;
5181        let mut diff_base_anchor = None;
5182        if let Some(DiffTransform::DeletedHunk {
5183            buffer_id,
5184            base_text_byte_range,
5185            has_trailing_newline,
5186            ..
5187        }) = diff_transforms.item()
5188        {
5189            let diff = self.diffs.get(buffer_id).expect("missing diff");
5190            if offset_in_transform > base_text_byte_range.len() {
5191                debug_assert!(*has_trailing_newline);
5192                bias = Bias::Right;
5193            } else {
5194                diff_base_anchor = Some(
5195                    diff.base_text()
5196                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5197                );
5198                bias = Bias::Left;
5199            }
5200        } else {
5201            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5202        };
5203
5204        let mut excerpts = self
5205            .excerpts
5206            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5207        excerpts.seek(&excerpt_offset, Bias::Right);
5208        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5209            excerpts.prev();
5210        }
5211        if let Some(excerpt) = excerpts.item() {
5212            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5213            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5214                overshoot -= 1;
5215                bias = Bias::Right;
5216            }
5217
5218            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5219            let text_anchor =
5220                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5221            let anchor = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor);
5222            match diff_base_anchor {
5223                Some(diff_base_anchor) => anchor.with_diff_base_anchor(diff_base_anchor),
5224                None => anchor,
5225            }
5226        } else if excerpt_offset.is_zero() && bias == Bias::Left {
5227            Anchor::min()
5228        } else {
5229            Anchor::max()
5230        }
5231    }
5232
5233    /// Returns an anchor for the given excerpt and text anchor,
5234    /// returns None if the excerpt_id is no longer valid.
5235    pub fn anchor_in_excerpt(
5236        &self,
5237        excerpt_id: ExcerptId,
5238        text_anchor: text::Anchor,
5239    ) -> Option<Anchor> {
5240        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5241        let excerpt = self.excerpt(excerpt_id)?;
5242        Some(Anchor::in_buffer(
5243            excerpt_id,
5244            excerpt.buffer_id,
5245            text_anchor,
5246        ))
5247    }
5248
5249    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5250        Some(self.excerpt(excerpt_id)?.range.context.clone())
5251    }
5252
5253    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5254        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5255            true
5256        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5257            excerpt.buffer.can_resolve(&anchor.text_anchor)
5258        } else {
5259            false
5260        }
5261    }
5262
5263    pub fn excerpts(
5264        &self,
5265    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5266        self.excerpts
5267            .iter()
5268            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5269    }
5270
5271    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5272        let excerpts = self.excerpts.cursor(());
5273        let diff_transforms = self.diff_transforms.cursor(());
5274        MultiBufferCursor {
5275            excerpts,
5276            diff_transforms,
5277            diffs: &self.diffs,
5278            cached_region: None,
5279        }
5280    }
5281
5282    pub fn excerpt_before(&self, excerpt_id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5283        let start_locator = self.excerpt_locator_for_id(excerpt_id);
5284        let mut excerpts = self
5285            .excerpts
5286            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(());
5287        excerpts.seek(&Some(start_locator), Bias::Left);
5288        excerpts.prev();
5289
5290        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(());
5291        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5292        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5293            diff_transforms.next();
5294        }
5295
5296        let excerpt = excerpts.item()?;
5297        Some(MultiBufferExcerpt {
5298            excerpt,
5299            offset: diff_transforms.start().output_dimension.0,
5300            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5301            excerpt_offset: excerpts.start().1.clone(),
5302            diff_transforms,
5303        })
5304    }
5305
5306    pub fn excerpt_boundaries_in_range<R, T>(
5307        &self,
5308        range: R,
5309    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5310    where
5311        R: RangeBounds<T>,
5312        T: ToOffset,
5313    {
5314        let start_offset;
5315        let start = match range.start_bound() {
5316            Bound::Included(start) => {
5317                start_offset = start.to_offset(self);
5318                Bound::Included(start_offset)
5319            }
5320            Bound::Excluded(_) => {
5321                panic!("not supported")
5322            }
5323            Bound::Unbounded => {
5324                start_offset = 0;
5325                Bound::Unbounded
5326            }
5327        };
5328        let end = match range.end_bound() {
5329            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5330            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5331            Bound::Unbounded => Bound::Unbounded,
5332        };
5333        let bounds = (start, end);
5334
5335        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5336        cursor.seek(&DimensionPair {
5337            key: start_offset,
5338            value: None,
5339        });
5340
5341        if cursor
5342            .region()
5343            .is_some_and(|region| bounds.contains(&region.range.start.key))
5344        {
5345            cursor.prev_excerpt();
5346        } else {
5347            cursor.seek_to_start_of_current_excerpt();
5348        }
5349        let mut prev_region = cursor.region();
5350
5351        cursor.next_excerpt();
5352
5353        iter::from_fn(move || {
5354            loop {
5355                if self.singleton {
5356                    return None;
5357                }
5358
5359                let next_region = cursor.region()?;
5360                cursor.next_excerpt();
5361                if !bounds.contains(&next_region.range.start.key) {
5362                    prev_region = Some(next_region);
5363                    continue;
5364                }
5365
5366                let next_region_start = next_region.range.start.value.unwrap();
5367                let next_region_end = if let Some(region) = cursor.region() {
5368                    region.range.start.value.unwrap()
5369                } else {
5370                    self.max_point()
5371                };
5372
5373                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5374                    id: region.excerpt.id,
5375                    buffer: region.excerpt.buffer.clone(),
5376                    buffer_id: region.excerpt.buffer_id,
5377                    range: region.excerpt.range.clone(),
5378                    end_row: MultiBufferRow(next_region_start.row),
5379                });
5380
5381                let next = ExcerptInfo {
5382                    id: next_region.excerpt.id,
5383                    buffer: next_region.excerpt.buffer.clone(),
5384                    buffer_id: next_region.excerpt.buffer_id,
5385                    range: next_region.excerpt.range.clone(),
5386                    end_row: if next_region.excerpt.has_trailing_newline {
5387                        MultiBufferRow(next_region_end.row - 1)
5388                    } else {
5389                        MultiBufferRow(next_region_end.row)
5390                    },
5391                };
5392
5393                let row = MultiBufferRow(next_region_start.row);
5394
5395                prev_region = Some(next_region);
5396
5397                return Some(ExcerptBoundary { row, prev, next });
5398            }
5399        })
5400    }
5401
5402    pub fn edit_count(&self) -> usize {
5403        self.edit_count
5404    }
5405
5406    pub fn non_text_state_update_count(&self) -> usize {
5407        self.non_text_state_update_count
5408    }
5409
5410    /// Returns the smallest enclosing bracket ranges containing the given range or
5411    /// None if no brackets contain range or the range is not contained in a single
5412    /// excerpt
5413    ///
5414    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5415    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5416        &self,
5417        range: Range<T>,
5418        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5419    ) -> Option<(Range<usize>, Range<usize>)> {
5420        let range = range.start.to_offset(self)..range.end.to_offset(self);
5421        let mut excerpt = self.excerpt_containing(range.clone())?;
5422        let buffer = excerpt.buffer();
5423        let excerpt_buffer_range = excerpt.buffer_range();
5424
5425        // Filter to ranges contained in the excerpt
5426        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5427            excerpt_buffer_range.contains(&open.start)
5428                && excerpt_buffer_range.contains(&close.end)
5429                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5430        };
5431
5432        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5433            excerpt.map_range_to_buffer(range),
5434            Some(&range_filter),
5435        )?;
5436
5437        Some((
5438            excerpt.map_range_from_buffer(open),
5439            excerpt.map_range_from_buffer(close),
5440        ))
5441    }
5442
5443    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5444    /// not contained in a single excerpt
5445    pub fn enclosing_bracket_ranges<T: ToOffset>(
5446        &self,
5447        range: Range<T>,
5448    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5449        let range = range.start.to_offset(self)..range.end.to_offset(self);
5450        let mut excerpt = self.excerpt_containing(range.clone())?;
5451
5452        Some(
5453            excerpt
5454                .buffer()
5455                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5456                .filter_map(move |pair| {
5457                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5458                        Some((
5459                            excerpt.map_range_from_buffer(pair.open_range),
5460                            excerpt.map_range_from_buffer(pair.close_range),
5461                        ))
5462                    } else {
5463                        None
5464                    }
5465                }),
5466        )
5467    }
5468
5469    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5470    /// not contained in a single excerpt
5471    pub fn text_object_ranges<T: ToOffset>(
5472        &self,
5473        range: Range<T>,
5474        options: TreeSitterOptions,
5475    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5476        let range = range.start.to_offset(self)..range.end.to_offset(self);
5477        self.excerpt_containing(range.clone())
5478            .map(|mut excerpt| {
5479                excerpt
5480                    .buffer()
5481                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5482                    .filter_map(move |(range, text_object)| {
5483                        if excerpt.contains_buffer_range(range.clone()) {
5484                            Some((excerpt.map_range_from_buffer(range), text_object))
5485                        } else {
5486                            None
5487                        }
5488                    })
5489            })
5490            .into_iter()
5491            .flatten()
5492    }
5493
5494    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5495    /// not contained in a single excerpt
5496    pub fn bracket_ranges<T: ToOffset>(
5497        &self,
5498        range: Range<T>,
5499    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5500        let range = range.start.to_offset(self)..range.end.to_offset(self);
5501        let mut excerpt = self.excerpt_containing(range.clone())?;
5502
5503        Some(
5504            excerpt
5505                .buffer()
5506                .bracket_ranges(excerpt.map_range_to_buffer(range))
5507                .filter_map(move |pair| {
5508                    let buffer_range = pair.open_range.start..pair.close_range.end;
5509                    if excerpt.contains_buffer_range(buffer_range) {
5510                        Some((
5511                            excerpt.map_range_from_buffer(pair.open_range),
5512                            excerpt.map_range_from_buffer(pair.close_range),
5513                        ))
5514                    } else {
5515                        None
5516                    }
5517                }),
5518        )
5519    }
5520
5521    pub fn redacted_ranges<'a, T: ToOffset>(
5522        &'a self,
5523        range: Range<T>,
5524        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5525    ) -> impl Iterator<Item = Range<usize>> + 'a {
5526        let range = range.start.to_offset(self)..range.end.to_offset(self);
5527        self.lift_buffer_metadata(range, move |buffer, range| {
5528            if redaction_enabled(buffer.file()) {
5529                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5530            } else {
5531                None
5532            }
5533        })
5534        .map(|(range, _, _)| range)
5535    }
5536
5537    pub fn runnable_ranges(
5538        &self,
5539        range: Range<Anchor>,
5540    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5541        let range = range.start.to_offset(self)..range.end.to_offset(self);
5542        self.lift_buffer_metadata(range, move |buffer, range| {
5543            Some(
5544                buffer
5545                    .runnable_ranges(range.clone())
5546                    .filter(move |runnable| {
5547                        runnable.run_range.start >= range.start
5548                            && runnable.run_range.end < range.end
5549                    })
5550                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5551            )
5552        })
5553        .map(|(run_range, runnable, _)| language::RunnableRange {
5554            run_range,
5555            ..runnable
5556        })
5557    }
5558
5559    pub fn line_indents(
5560        &self,
5561        start_row: MultiBufferRow,
5562        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5563    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5564        let max_point = self.max_point();
5565        let mut cursor = self.cursor::<Point>();
5566        cursor.seek(&Point::new(start_row.0, 0));
5567        iter::from_fn(move || {
5568            let mut region = cursor.region()?;
5569            while !buffer_filter(&region.excerpt.buffer) {
5570                cursor.next();
5571                region = cursor.region()?;
5572            }
5573            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5574            let buffer_start_row =
5575                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5576
5577            let buffer_end_row = if region.is_main_buffer
5578                && (region.has_trailing_newline || region.range.end == max_point)
5579            {
5580                region.buffer_range.end.row
5581            } else {
5582                region.buffer_range.end.row.saturating_sub(1)
5583            };
5584
5585            let line_indents = region
5586                .buffer
5587                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5588            cursor.next();
5589            Some(line_indents.map(move |(buffer_row, indent)| {
5590                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5591                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5592            }))
5593        })
5594        .flatten()
5595    }
5596
5597    pub fn reversed_line_indents(
5598        &self,
5599        end_row: MultiBufferRow,
5600        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5601    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5602        let max_point = self.max_point();
5603        let mut cursor = self.cursor::<Point>();
5604        cursor.seek(&Point::new(end_row.0, 0));
5605        iter::from_fn(move || {
5606            let mut region = cursor.region()?;
5607            while !buffer_filter(&region.excerpt.buffer) {
5608                cursor.prev();
5609                region = cursor.region()?;
5610            }
5611
5612            let buffer_start_row = region.buffer_range.start.row;
5613            let buffer_end_row = if region.is_main_buffer
5614                && (region.has_trailing_newline || region.range.end == max_point)
5615            {
5616                region.buffer_range.end.row + 1
5617            } else {
5618                region.buffer_range.end.row
5619            };
5620
5621            let overshoot = end_row.0 - region.range.start.row;
5622            let buffer_end_row =
5623                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5624
5625            let line_indents = region
5626                .buffer
5627                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5628            cursor.prev();
5629            Some(line_indents.map(move |(buffer_row, indent)| {
5630                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5631                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5632            }))
5633        })
5634        .flatten()
5635    }
5636
5637    pub async fn enclosing_indent(
5638        &self,
5639        mut target_row: MultiBufferRow,
5640    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5641        let max_row = MultiBufferRow(self.max_point().row);
5642        if target_row >= max_row {
5643            return None;
5644        }
5645
5646        let mut target_indent = self.line_indent_for_row(target_row);
5647
5648        // If the current row is at the start of an indented block, we want to return this
5649        // block as the enclosing indent.
5650        if !target_indent.is_line_empty() && target_row < max_row {
5651            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5652            if !next_line_indent.is_line_empty()
5653                && target_indent.raw_len() < next_line_indent.raw_len()
5654            {
5655                target_indent = next_line_indent;
5656                target_row.0 += 1;
5657            }
5658        }
5659
5660        const SEARCH_ROW_LIMIT: u32 = 25000;
5661        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5662        const YIELD_INTERVAL: u32 = 100;
5663
5664        let mut accessed_row_counter = 0;
5665
5666        // If there is a blank line at the current row, search for the next non indented lines
5667        if target_indent.is_line_empty() {
5668            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5669            let end =
5670                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5671
5672            let mut non_empty_line_above = None;
5673            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5674                if row < start {
5675                    break;
5676                }
5677                accessed_row_counter += 1;
5678                if accessed_row_counter == YIELD_INTERVAL {
5679                    accessed_row_counter = 0;
5680                    yield_now().await;
5681                }
5682                if !indent.is_line_empty() {
5683                    non_empty_line_above = Some((row, indent));
5684                    break;
5685                }
5686            }
5687
5688            let mut non_empty_line_below = None;
5689            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5690                if row > end {
5691                    break;
5692                }
5693                accessed_row_counter += 1;
5694                if accessed_row_counter == YIELD_INTERVAL {
5695                    accessed_row_counter = 0;
5696                    yield_now().await;
5697                }
5698                if !indent.is_line_empty() {
5699                    non_empty_line_below = Some((row, indent));
5700                    break;
5701                }
5702            }
5703
5704            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5705                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5706                    if above_indent.raw_len() >= below_indent.raw_len() {
5707                        (above_row, above_indent)
5708                    } else {
5709                        (below_row, below_indent)
5710                    }
5711                }
5712                (Some(above), None) => above,
5713                (None, Some(below)) => below,
5714                _ => return None,
5715            };
5716
5717            target_indent = indent;
5718            target_row = row;
5719        }
5720
5721        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5722        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5723
5724        let mut start_indent = None;
5725        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5726            if row < start {
5727                break;
5728            }
5729            accessed_row_counter += 1;
5730            if accessed_row_counter == YIELD_INTERVAL {
5731                accessed_row_counter = 0;
5732                yield_now().await;
5733            }
5734            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5735                start_indent = Some((row, indent));
5736                break;
5737            }
5738        }
5739        let (start_row, start_indent_size) = start_indent?;
5740
5741        let mut end_indent = (end, None);
5742        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5743            if row > end {
5744                break;
5745            }
5746            accessed_row_counter += 1;
5747            if accessed_row_counter == YIELD_INTERVAL {
5748                accessed_row_counter = 0;
5749                yield_now().await;
5750            }
5751            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5752                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5753                break;
5754            }
5755        }
5756        let (end_row, end_indent_size) = end_indent;
5757
5758        let indent = if let Some(end_indent_size) = end_indent_size {
5759            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5760                start_indent_size
5761            } else {
5762                end_indent_size
5763            }
5764        } else {
5765            start_indent_size
5766        };
5767
5768        Some((start_row..end_row, indent))
5769    }
5770
5771    pub fn indent_guides_in_range<T: ToPoint>(
5772        &self,
5773        range: Range<T>,
5774        ignore_disabled_for_language: bool,
5775        cx: &App,
5776    ) -> impl Iterator<Item = IndentGuide> {
5777        let range = range.start.to_point(self)..range.end.to_point(self);
5778        let start_row = MultiBufferRow(range.start.row);
5779        let end_row = MultiBufferRow(range.end.row);
5780
5781        let mut row_indents = self.line_indents(start_row, |buffer| {
5782            let settings =
5783                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5784            settings.indent_guides.enabled || ignore_disabled_for_language
5785        });
5786
5787        let mut result = Vec::new();
5788        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5789
5790        let mut prev_settings = None;
5791        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5792            if first_row > end_row {
5793                break;
5794            }
5795            let current_depth = indent_stack.len() as u32;
5796
5797            // Avoid retrieving the language settings repeatedly for every buffer row.
5798            if let Some((prev_buffer_id, _)) = &prev_settings
5799                && prev_buffer_id != &buffer.remote_id()
5800            {
5801                prev_settings.take();
5802            }
5803            let settings = &prev_settings
5804                .get_or_insert_with(|| {
5805                    (
5806                        buffer.remote_id(),
5807                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5808                    )
5809                })
5810                .1;
5811            let tab_size = settings.tab_size.get();
5812
5813            // When encountering empty, continue until found useful line indent
5814            // then add to the indent stack with the depth found
5815            let mut found_indent = false;
5816            let mut last_row = first_row;
5817            if line_indent.is_line_blank() {
5818                while !found_indent {
5819                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5820                        break;
5821                    };
5822                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5823                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5824                        break;
5825                    }
5826
5827                    if new_line_indent.is_line_blank() {
5828                        continue;
5829                    }
5830                    last_row = target_row.min(end_row);
5831                    line_indent = new_line_indent;
5832                    found_indent = true;
5833                    break;
5834                }
5835            } else {
5836                found_indent = true
5837            }
5838
5839            let depth = if found_indent {
5840                line_indent.len(tab_size) / tab_size
5841            } else {
5842                0
5843            };
5844
5845            match depth.cmp(&current_depth) {
5846                cmp::Ordering::Less => {
5847                    for _ in 0..(current_depth - depth) {
5848                        let mut indent = indent_stack.pop().unwrap();
5849                        if last_row != first_row {
5850                            // In this case, we landed on an empty row, had to seek forward,
5851                            // and discovered that the indent we where on is ending.
5852                            // This means that the last display row must
5853                            // be on line that ends this indent range, so we
5854                            // should display the range up to the first non-empty line
5855                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5856                        }
5857
5858                        result.push(indent)
5859                    }
5860                }
5861                cmp::Ordering::Greater => {
5862                    for next_depth in current_depth..depth {
5863                        indent_stack.push(IndentGuide {
5864                            buffer_id: buffer.remote_id(),
5865                            start_row: first_row,
5866                            end_row: last_row,
5867                            depth: next_depth,
5868                            tab_size,
5869                            settings: settings.indent_guides.clone(),
5870                        });
5871                    }
5872                }
5873                _ => {}
5874            }
5875
5876            for indent in indent_stack.iter_mut() {
5877                indent.end_row = last_row;
5878            }
5879        }
5880
5881        result.extend(indent_stack);
5882        result.into_iter()
5883    }
5884
5885    pub fn trailing_excerpt_update_count(&self) -> usize {
5886        self.trailing_excerpt_update_count
5887    }
5888
5889    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5890        self.point_to_buffer_offset(point)
5891            .and_then(|(buffer, _)| buffer.file())
5892    }
5893
5894    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5895        self.point_to_buffer_offset(point)
5896            .and_then(|(buffer, offset)| buffer.language_at(offset))
5897    }
5898
5899    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5900        self.excerpts
5901            .first()
5902            .map(|excerpt| &excerpt.buffer)
5903            .map(|buffer| {
5904                language_settings(
5905                    buffer.language().map(|language| language.name()),
5906                    buffer.file(),
5907                    cx,
5908                )
5909            })
5910            .unwrap_or_else(move || self.language_settings_at(0, cx))
5911    }
5912
5913    pub fn language_settings_at<'a, T: ToOffset>(
5914        &'a self,
5915        point: T,
5916        cx: &'a App,
5917    ) -> Cow<'a, LanguageSettings> {
5918        let mut language = None;
5919        let mut file = None;
5920        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5921            language = buffer.language_at(offset);
5922            file = buffer.file();
5923        }
5924        language_settings(language.map(|l| l.name()), file, cx)
5925    }
5926
5927    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5928        self.point_to_buffer_offset(point)
5929            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5930    }
5931
5932    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5933        self.point_to_buffer_offset(point)
5934            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5935            .unwrap_or_default()
5936    }
5937
5938    pub fn language_indent_size_at<T: ToOffset>(
5939        &self,
5940        position: T,
5941        cx: &App,
5942    ) -> Option<IndentSize> {
5943        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5944        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5945    }
5946
5947    pub fn is_dirty(&self) -> bool {
5948        self.is_dirty
5949    }
5950
5951    pub fn has_deleted_file(&self) -> bool {
5952        self.has_deleted_file
5953    }
5954
5955    pub fn has_conflict(&self) -> bool {
5956        self.has_conflict
5957    }
5958
5959    pub fn has_diagnostics(&self) -> bool {
5960        self.excerpts
5961            .iter()
5962            .any(|excerpt| excerpt.buffer.has_diagnostics())
5963    }
5964
5965    pub fn diagnostic_group(
5966        &self,
5967        buffer_id: BufferId,
5968        group_id: usize,
5969    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
5970        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
5971            if buffer.remote_id() != buffer_id {
5972                return None;
5973            };
5974            Some(
5975                buffer
5976                    .diagnostics_in_range(range, false)
5977                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
5978                    .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
5979            )
5980        })
5981        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
5982    }
5983
5984    pub fn diagnostics_in_range<'a, T>(
5985        &'a self,
5986        range: Range<T>,
5987    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, T>> + 'a
5988    where
5989        T: 'a
5990            + text::ToOffset
5991            + text::FromAnchor
5992            + TextDimension
5993            + Ord
5994            + Sub<T, Output = T>
5995            + fmt::Debug,
5996    {
5997        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
5998            Some(
5999                buffer
6000                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6001                    .map(|entry| (entry.range, entry.diagnostic)),
6002            )
6003        })
6004        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6005    }
6006
6007    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6008        &'a self,
6009        range: Range<T>,
6010    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, T>)> + 'a
6011    where
6012        T: 'a
6013            + text::ToOffset
6014            + text::FromAnchor
6015            + TextDimension
6016            + Ord
6017            + Sub<T, Output = T>
6018            + fmt::Debug,
6019    {
6020        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6021            Some(
6022                buffer
6023                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6024                    .map(|entry| (entry.range, entry.diagnostic)),
6025            )
6026        })
6027        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6028    }
6029
6030    pub fn syntax_ancestor<T: ToOffset>(
6031        &self,
6032        range: Range<T>,
6033    ) -> Option<(tree_sitter::Node<'_>, Range<usize>)> {
6034        let range = range.start.to_offset(self)..range.end.to_offset(self);
6035        let mut excerpt = self.excerpt_containing(range.clone())?;
6036        let node = excerpt
6037            .buffer()
6038            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6039        let node_range = node.byte_range();
6040        if !excerpt.contains_buffer_range(node_range.clone()) {
6041            return None;
6042        };
6043        Some((node, excerpt.map_range_from_buffer(node_range)))
6044    }
6045
6046    pub fn syntax_next_sibling<T: ToOffset>(
6047        &self,
6048        range: Range<T>,
6049    ) -> Option<tree_sitter::Node<'_>> {
6050        let range = range.start.to_offset(self)..range.end.to_offset(self);
6051        let mut excerpt = self.excerpt_containing(range.clone())?;
6052        excerpt
6053            .buffer()
6054            .syntax_next_sibling(excerpt.map_range_to_buffer(range))
6055    }
6056
6057    pub fn syntax_prev_sibling<T: ToOffset>(
6058        &self,
6059        range: Range<T>,
6060    ) -> Option<tree_sitter::Node<'_>> {
6061        let range = range.start.to_offset(self)..range.end.to_offset(self);
6062        let mut excerpt = self.excerpt_containing(range.clone())?;
6063        excerpt
6064            .buffer()
6065            .syntax_prev_sibling(excerpt.map_range_to_buffer(range))
6066    }
6067
6068    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6069        let (excerpt_id, _, buffer) = self.as_singleton()?;
6070        let outline = buffer.outline(theme);
6071        Some(Outline::new(
6072            outline
6073                .items
6074                .into_iter()
6075                .flat_map(|item| {
6076                    Some(OutlineItem {
6077                        depth: item.depth,
6078                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6079                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6080                        text: item.text,
6081                        highlight_ranges: item.highlight_ranges,
6082                        name_ranges: item.name_ranges,
6083                        body_range: item.body_range.and_then(|body_range| {
6084                            Some(
6085                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6086                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6087                            )
6088                        }),
6089                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6090                            Some(
6091                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6092                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6093                            )
6094                        }),
6095                    })
6096                })
6097                .collect(),
6098        ))
6099    }
6100
6101    pub fn symbols_containing<T: ToOffset>(
6102        &self,
6103        offset: T,
6104        theme: Option<&SyntaxTheme>,
6105    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6106        let anchor = self.anchor_before(offset);
6107        let excerpt_id = anchor.excerpt_id;
6108        let excerpt = self.excerpt(excerpt_id)?;
6109        let buffer_id = excerpt.buffer_id;
6110        Some((
6111            buffer_id,
6112            excerpt
6113                .buffer
6114                .symbols_containing(anchor.text_anchor, theme)
6115                .into_iter()
6116                .flat_map(|item| {
6117                    Some(OutlineItem {
6118                        depth: item.depth,
6119                        range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
6120                        text: item.text,
6121                        highlight_ranges: item.highlight_ranges,
6122                        name_ranges: item.name_ranges,
6123                        body_range: item.body_range.map(|body_range| {
6124                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6125                        }),
6126                        annotation_range: item.annotation_range.map(|body_range| {
6127                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6128                        }),
6129                    })
6130                })
6131                .collect(),
6132        ))
6133    }
6134
6135    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6136        if id == ExcerptId::min() {
6137            Locator::min_ref()
6138        } else if id == ExcerptId::max() {
6139            Locator::max_ref()
6140        } else {
6141            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6142            cursor.seek(&id, Bias::Left);
6143            if let Some(entry) = cursor.item()
6144                && entry.id == id
6145            {
6146                return &entry.locator;
6147            }
6148            panic!("invalid excerpt id {id:?}")
6149        }
6150    }
6151
6152    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6153    fn excerpt_locators_for_ids(
6154        &self,
6155        ids: impl IntoIterator<Item = ExcerptId>,
6156    ) -> SmallVec<[Locator; 1]> {
6157        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6158        sorted_ids.sort_unstable();
6159        let mut locators = SmallVec::new();
6160
6161        while sorted_ids.last() == Some(&ExcerptId::max()) {
6162            sorted_ids.pop();
6163            if let Some(mapping) = self.excerpt_ids.last() {
6164                locators.push(mapping.locator.clone());
6165            }
6166        }
6167
6168        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6169        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6170            sorted_ids.next();
6171            if let Some(mapping) = self.excerpt_ids.first() {
6172                locators.push(mapping.locator.clone());
6173            }
6174        }
6175
6176        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6177        for id in sorted_ids {
6178            if cursor.seek_forward(&id, Bias::Left) {
6179                locators.push(cursor.item().unwrap().locator.clone());
6180            } else {
6181                panic!("invalid excerpt id {:?}", id);
6182            }
6183        }
6184
6185        locators.sort_unstable();
6186        locators
6187    }
6188
6189    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6190        Some(self.excerpt(excerpt_id)?.buffer_id)
6191    }
6192
6193    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6194        Some(&self.excerpt(excerpt_id)?.buffer)
6195    }
6196
6197    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6198        let mut cursor = self
6199            .excerpts
6200            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
6201        let locator = self.excerpt_locator_for_id(excerpt_id);
6202        let mut sought_exact = cursor.seek(&Some(locator), Bias::Left);
6203        if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
6204            sought_exact = true;
6205            cursor.prev();
6206        } else if excerpt_id == ExcerptId::min() {
6207            sought_exact = true;
6208        }
6209        if sought_exact {
6210            let start = cursor.start().1.clone();
6211            let end = cursor.end().1;
6212            let mut diff_transforms = self
6213                .diff_transforms
6214                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
6215            diff_transforms.seek(&start, Bias::Left);
6216            let overshoot = start.0 - diff_transforms.start().0.0;
6217            let start = diff_transforms.start().1.0 + overshoot;
6218            diff_transforms.seek(&end, Bias::Right);
6219            let overshoot = end.0 - diff_transforms.start().0.0;
6220            let end = diff_transforms.start().1.0 + overshoot;
6221            Some(start..end)
6222        } else {
6223            None
6224        }
6225    }
6226
6227    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6228        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6229        let locator = self.excerpt_locator_for_id(excerpt_id);
6230        cursor.seek(&Some(locator), Bias::Left);
6231        if let Some(excerpt) = cursor.item()
6232            && excerpt.id == excerpt_id
6233        {
6234            return Some(excerpt);
6235        } else if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
6236            cursor.prev();
6237            return cursor.item();
6238        }
6239        None
6240    }
6241
6242    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6243    pub fn excerpt_containing<T: ToOffset>(
6244        &self,
6245        range: Range<T>,
6246    ) -> Option<MultiBufferExcerpt<'_>> {
6247        let range = range.start.to_offset(self)..range.end.to_offset(self);
6248        let mut cursor = self.cursor::<usize>();
6249        cursor.seek(&range.start);
6250
6251        let start_excerpt = cursor.excerpt()?;
6252        if range.end != range.start {
6253            cursor.seek_forward(&range.end);
6254            if cursor.excerpt()?.id != start_excerpt.id {
6255                return None;
6256            }
6257        }
6258
6259        cursor.seek_to_start_of_current_excerpt();
6260        let region = cursor.region()?;
6261        let offset = region.range.start;
6262        let buffer_offset = start_excerpt.buffer_start_offset();
6263        let excerpt_offset = cursor.excerpts.start().clone();
6264        Some(MultiBufferExcerpt {
6265            diff_transforms: cursor.diff_transforms,
6266            excerpt: start_excerpt,
6267            offset,
6268            buffer_offset,
6269            excerpt_offset,
6270        })
6271    }
6272
6273    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
6274        if let Some(id) = anchor.buffer_id {
6275            return Some(id);
6276        }
6277        let excerpt = self.excerpt_containing(anchor..anchor)?;
6278        Some(excerpt.buffer_id())
6279    }
6280
6281    pub fn selections_in_range<'a>(
6282        &'a self,
6283        range: &'a Range<Anchor>,
6284        include_local: bool,
6285    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6286        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
6287        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6288        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6289        cursor.seek(start_locator, Bias::Left);
6290        cursor
6291            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6292            .flat_map(move |excerpt| {
6293                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6294                if excerpt.id == range.start.excerpt_id {
6295                    query_range.start = range.start.text_anchor;
6296                }
6297                if excerpt.id == range.end.excerpt_id {
6298                    query_range.end = range.end.text_anchor;
6299                }
6300
6301                excerpt
6302                    .buffer
6303                    .selections_in_range(query_range, include_local)
6304                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6305                        selections.map(move |selection| {
6306                            let mut start =
6307                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.start);
6308                            let mut end =
6309                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.end);
6310                            if range.start.cmp(&start, self).is_gt() {
6311                                start = range.start;
6312                            }
6313                            if range.end.cmp(&end, self).is_lt() {
6314                                end = range.end;
6315                            }
6316
6317                            (
6318                                replica_id,
6319                                line_mode,
6320                                cursor_shape,
6321                                Selection {
6322                                    id: selection.id,
6323                                    start,
6324                                    end,
6325                                    reversed: selection.reversed,
6326                                    goal: selection.goal,
6327                                },
6328                            )
6329                        })
6330                    })
6331            })
6332    }
6333
6334    pub fn show_headers(&self) -> bool {
6335        self.show_headers
6336    }
6337
6338    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6339        self.diffs.get(&buffer_id)
6340    }
6341
6342    /// Visually annotates a position or range with the `Debug` representation of a value. The
6343    /// callsite of this function is used as a key - previous annotations will be removed.
6344    #[cfg(debug_assertions)]
6345    #[track_caller]
6346    pub fn debug<V, R>(&self, ranges: &R, value: V)
6347    where
6348        R: debug::ToMultiBufferDebugRanges,
6349        V: std::fmt::Debug,
6350    {
6351        self.debug_with_key(std::panic::Location::caller(), ranges, value);
6352    }
6353
6354    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
6355    /// debug annotations with the same key will be removed. The key is also used to determine the
6356    /// annotation's color.
6357    #[cfg(debug_assertions)]
6358    #[track_caller]
6359    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
6360    where
6361        K: std::hash::Hash + 'static,
6362        R: debug::ToMultiBufferDebugRanges,
6363        V: std::fmt::Debug,
6364    {
6365        let text_ranges = ranges
6366            .to_multi_buffer_debug_ranges(self)
6367            .into_iter()
6368            .flat_map(|range| {
6369                self.range_to_buffer_ranges(range).into_iter().map(
6370                    |(buffer, range, _excerpt_id)| {
6371                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
6372                    },
6373                )
6374            })
6375            .collect();
6376        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
6377            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
6378        });
6379    }
6380
6381    // used by line_mode selections and tries to match vim behavior
6382    pub fn expand_to_line(&self, range: Range<Point>) -> Range<Point> {
6383        let new_start = MultiBufferPoint::new(range.start.row, 0);
6384        let new_end = if range.end.column > 0 {
6385            MultiBufferPoint::new(range.end.row, self.line_len(MultiBufferRow(range.end.row)))
6386        } else {
6387            range.end
6388        };
6389        new_start..new_end
6390    }
6391}
6392
6393#[cfg(any(test, feature = "test-support"))]
6394impl MultiBufferSnapshot {
6395    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6396        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
6397        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
6398        start..end
6399    }
6400
6401    #[cfg(any(test, feature = "test-support"))]
6402    fn check_invariants(&self) {
6403        let excerpts = self.excerpts.items(());
6404        let excerpt_ids = self.excerpt_ids.items(());
6405
6406        for (ix, excerpt) in excerpts.iter().enumerate() {
6407            if ix == 0 {
6408                if excerpt.locator <= Locator::min() {
6409                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6410                }
6411            } else if excerpt.locator <= excerpts[ix - 1].locator {
6412                panic!("excerpts are out-of-order: {:?}", excerpts);
6413            }
6414        }
6415
6416        for (ix, entry) in excerpt_ids.iter().enumerate() {
6417            if ix == 0 {
6418                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6419                    panic!("invalid first excerpt id {:?}", entry.id);
6420                }
6421            } else if entry.id <= excerpt_ids[ix - 1].id {
6422                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6423            }
6424        }
6425
6426        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6427            panic!(
6428                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6429                self.excerpts.summary().text.len,
6430                self.diff_transforms.summary().input,
6431                self.diff_transforms.items(()),
6432            );
6433        }
6434
6435        let mut prev_transform: Option<&DiffTransform> = None;
6436        for item in self.diff_transforms.iter() {
6437            if let DiffTransform::BufferContent {
6438                summary,
6439                inserted_hunk_info,
6440            } = item
6441            {
6442                if let Some(DiffTransform::BufferContent {
6443                    inserted_hunk_info: prev_inserted_hunk_info,
6444                    ..
6445                }) = prev_transform
6446                    && *inserted_hunk_info == *prev_inserted_hunk_info
6447                {
6448                    panic!(
6449                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6450                        self.diff_transforms.items(())
6451                    );
6452                }
6453                if summary.len == 0 && !self.is_empty() {
6454                    panic!("empty buffer content transform");
6455                }
6456            }
6457            prev_transform = Some(item);
6458        }
6459    }
6460}
6461
6462impl<'a, D> MultiBufferCursor<'a, D>
6463where
6464    D: TextDimension + Ord + Sub<D, Output = D>,
6465{
6466    fn seek(&mut self, position: &D) {
6467        self.cached_region.take();
6468        self.diff_transforms
6469            .seek(&OutputDimension(*position), Bias::Right);
6470        if self.diff_transforms.item().is_none()
6471            && *position == self.diff_transforms.start().output_dimension.0
6472        {
6473            self.diff_transforms.prev();
6474        }
6475
6476        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6477        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6478            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6479            excerpt_position.add_assign(&overshoot);
6480        }
6481
6482        self.excerpts
6483            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6484        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6485            self.excerpts.prev();
6486        }
6487    }
6488
6489    fn seek_forward(&mut self, position: &D) {
6490        self.cached_region.take();
6491        self.diff_transforms
6492            .seek_forward(&OutputDimension(*position), Bias::Right);
6493        if self.diff_transforms.item().is_none()
6494            && *position == self.diff_transforms.start().output_dimension.0
6495        {
6496            self.diff_transforms.prev();
6497        }
6498
6499        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6500        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6501        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6502            excerpt_position.add_assign(&overshoot);
6503        }
6504
6505        self.excerpts
6506            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6507        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6508            self.excerpts.prev();
6509        }
6510    }
6511
6512    fn next_excerpt(&mut self) {
6513        self.excerpts.next();
6514        self.seek_to_start_of_current_excerpt();
6515    }
6516
6517    fn prev_excerpt(&mut self) {
6518        self.excerpts.prev();
6519        self.seek_to_start_of_current_excerpt();
6520    }
6521
6522    fn seek_to_start_of_current_excerpt(&mut self) {
6523        self.cached_region.take();
6524        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6525        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6526            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6527            && self.diff_transforms.next_item().is_some()
6528        {
6529            self.diff_transforms.next();
6530        }
6531    }
6532
6533    fn next(&mut self) {
6534        self.cached_region.take();
6535        match self
6536            .diff_transforms
6537            .end()
6538            .excerpt_dimension
6539            .cmp(&self.excerpts.end())
6540        {
6541            cmp::Ordering::Less => self.diff_transforms.next(),
6542            cmp::Ordering::Greater => self.excerpts.next(),
6543            cmp::Ordering::Equal => {
6544                self.diff_transforms.next();
6545                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6546                    || self.diff_transforms.item().is_none()
6547                {
6548                    self.excerpts.next();
6549                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6550                    self.diff_transforms.item()
6551                    && self
6552                        .excerpts
6553                        .item()
6554                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6555                {
6556                    self.excerpts.next();
6557                }
6558            }
6559        }
6560    }
6561
6562    fn prev(&mut self) {
6563        self.cached_region.take();
6564        match self
6565            .diff_transforms
6566            .start()
6567            .excerpt_dimension
6568            .cmp(self.excerpts.start())
6569        {
6570            cmp::Ordering::Less => self.excerpts.prev(),
6571            cmp::Ordering::Greater => self.diff_transforms.prev(),
6572            cmp::Ordering::Equal => {
6573                self.diff_transforms.prev();
6574                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6575                    || self.diff_transforms.item().is_none()
6576                {
6577                    self.excerpts.prev();
6578                }
6579            }
6580        }
6581    }
6582
6583    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6584        if self.cached_region.is_none() {
6585            self.cached_region = self.build_region();
6586        }
6587        self.cached_region.clone()
6588    }
6589
6590    fn is_at_start_of_excerpt(&mut self) -> bool {
6591        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6592            return false;
6593        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6594            return true;
6595        }
6596
6597        self.diff_transforms.prev();
6598        let prev_transform = self.diff_transforms.item();
6599        self.diff_transforms.next();
6600
6601        prev_transform.is_none_or(|next_transform| {
6602            matches!(next_transform, DiffTransform::BufferContent { .. })
6603        })
6604    }
6605
6606    fn is_at_end_of_excerpt(&mut self) -> bool {
6607        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6608            return false;
6609        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6610            || self.diff_transforms.item().is_none()
6611        {
6612            return true;
6613        }
6614
6615        let next_transform = self.diff_transforms.next_item();
6616        next_transform.is_none_or(|next_transform| match next_transform {
6617            DiffTransform::BufferContent { .. } => true,
6618            DiffTransform::DeletedHunk { hunk_info, .. } => self
6619                .excerpts
6620                .item()
6621                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6622        })
6623    }
6624
6625    fn main_buffer_position(&self) -> Option<D> {
6626        let excerpt = self.excerpts.item()?;
6627        let buffer = &excerpt.buffer;
6628        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6629        let mut buffer_start = buffer_context_start;
6630        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6631        buffer_start.add_assign(&overshoot);
6632        Some(buffer_start)
6633    }
6634
6635    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6636        let excerpt = self.excerpts.item()?;
6637        match self.diff_transforms.item()? {
6638            DiffTransform::DeletedHunk {
6639                buffer_id,
6640                base_text_byte_range,
6641                has_trailing_newline,
6642                hunk_info,
6643                ..
6644            } => {
6645                let diff = self.diffs.get(buffer_id)?;
6646                let buffer = diff.base_text();
6647                let mut rope_cursor = buffer.as_rope().cursor(0);
6648                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6649                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6650                let mut buffer_end = buffer_start;
6651                buffer_end.add_assign(&buffer_range_len);
6652                let start = self.diff_transforms.start().output_dimension.0;
6653                let end = self.diff_transforms.end().output_dimension.0;
6654                Some(MultiBufferRegion {
6655                    buffer,
6656                    excerpt,
6657                    has_trailing_newline: *has_trailing_newline,
6658                    is_main_buffer: false,
6659                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6660                        hunk_info.hunk_secondary_status,
6661                    )),
6662                    buffer_range: buffer_start..buffer_end,
6663                    range: start..end,
6664                })
6665            }
6666            DiffTransform::BufferContent {
6667                inserted_hunk_info, ..
6668            } => {
6669                let buffer = &excerpt.buffer;
6670                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6671
6672                let mut start = self.diff_transforms.start().output_dimension.0;
6673                let mut buffer_start = buffer_context_start;
6674                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6675                    let overshoot =
6676                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6677                    start.add_assign(&overshoot);
6678                } else {
6679                    let overshoot =
6680                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6681                    buffer_start.add_assign(&overshoot);
6682                }
6683
6684                let mut end;
6685                let mut buffer_end;
6686                let has_trailing_newline;
6687                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6688                    let overshoot =
6689                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6690                    end = self.diff_transforms.end().output_dimension.0;
6691                    buffer_end = buffer_context_start;
6692                    buffer_end.add_assign(&overshoot);
6693                    has_trailing_newline = false;
6694                } else {
6695                    let overshoot =
6696                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6697                    end = self.diff_transforms.start().output_dimension.0;
6698                    end.add_assign(&overshoot);
6699                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6700                    has_trailing_newline = excerpt.has_trailing_newline;
6701                };
6702
6703                Some(MultiBufferRegion {
6704                    buffer,
6705                    excerpt,
6706                    has_trailing_newline,
6707                    is_main_buffer: true,
6708                    diff_hunk_status: inserted_hunk_info
6709                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6710                    buffer_range: buffer_start..buffer_end,
6711                    range: start..end,
6712                })
6713            }
6714        }
6715    }
6716
6717    fn excerpt(&self) -> Option<&'a Excerpt> {
6718        self.excerpts.item()
6719    }
6720}
6721
6722impl History {
6723    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6724        self.transaction_depth += 1;
6725        if self.transaction_depth == 1 {
6726            let id = self.next_transaction_id.tick();
6727            self.undo_stack.push(Transaction {
6728                id,
6729                buffer_transactions: Default::default(),
6730                first_edit_at: now,
6731                last_edit_at: now,
6732                suppress_grouping: false,
6733            });
6734            Some(id)
6735        } else {
6736            None
6737        }
6738    }
6739
6740    fn end_transaction(
6741        &mut self,
6742        now: Instant,
6743        buffer_transactions: HashMap<BufferId, TransactionId>,
6744    ) -> bool {
6745        assert_ne!(self.transaction_depth, 0);
6746        self.transaction_depth -= 1;
6747        if self.transaction_depth == 0 {
6748            if buffer_transactions.is_empty() {
6749                self.undo_stack.pop();
6750                false
6751            } else {
6752                self.redo_stack.clear();
6753                let transaction = self.undo_stack.last_mut().unwrap();
6754                transaction.last_edit_at = now;
6755                for (buffer_id, transaction_id) in buffer_transactions {
6756                    transaction
6757                        .buffer_transactions
6758                        .entry(buffer_id)
6759                        .or_insert(transaction_id);
6760                }
6761                true
6762            }
6763        } else {
6764            false
6765        }
6766    }
6767
6768    fn push_transaction<'a, T>(
6769        &mut self,
6770        buffer_transactions: T,
6771        now: Instant,
6772        cx: &Context<MultiBuffer>,
6773    ) where
6774        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6775    {
6776        assert_eq!(self.transaction_depth, 0);
6777        let transaction = Transaction {
6778            id: self.next_transaction_id.tick(),
6779            buffer_transactions: buffer_transactions
6780                .into_iter()
6781                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6782                .collect(),
6783            first_edit_at: now,
6784            last_edit_at: now,
6785            suppress_grouping: false,
6786        };
6787        if !transaction.buffer_transactions.is_empty() {
6788            self.undo_stack.push(transaction);
6789            self.redo_stack.clear();
6790        }
6791    }
6792
6793    fn finalize_last_transaction(&mut self) {
6794        if let Some(transaction) = self.undo_stack.last_mut() {
6795            transaction.suppress_grouping = true;
6796        }
6797    }
6798
6799    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6800        if let Some(ix) = self
6801            .undo_stack
6802            .iter()
6803            .rposition(|transaction| transaction.id == transaction_id)
6804        {
6805            Some(self.undo_stack.remove(ix))
6806        } else if let Some(ix) = self
6807            .redo_stack
6808            .iter()
6809            .rposition(|transaction| transaction.id == transaction_id)
6810        {
6811            Some(self.redo_stack.remove(ix))
6812        } else {
6813            None
6814        }
6815    }
6816
6817    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6818        self.undo_stack
6819            .iter()
6820            .find(|transaction| transaction.id == transaction_id)
6821            .or_else(|| {
6822                self.redo_stack
6823                    .iter()
6824                    .find(|transaction| transaction.id == transaction_id)
6825            })
6826    }
6827
6828    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6829        self.undo_stack
6830            .iter_mut()
6831            .find(|transaction| transaction.id == transaction_id)
6832            .or_else(|| {
6833                self.redo_stack
6834                    .iter_mut()
6835                    .find(|transaction| transaction.id == transaction_id)
6836            })
6837    }
6838
6839    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6840        assert_eq!(self.transaction_depth, 0);
6841        if let Some(transaction) = self.undo_stack.pop() {
6842            self.redo_stack.push(transaction);
6843            self.redo_stack.last_mut()
6844        } else {
6845            None
6846        }
6847    }
6848
6849    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6850        assert_eq!(self.transaction_depth, 0);
6851        if let Some(transaction) = self.redo_stack.pop() {
6852            self.undo_stack.push(transaction);
6853            self.undo_stack.last_mut()
6854        } else {
6855            None
6856        }
6857    }
6858
6859    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6860        let ix = self
6861            .undo_stack
6862            .iter()
6863            .rposition(|transaction| transaction.id == transaction_id)?;
6864        let transaction = self.undo_stack.remove(ix);
6865        self.redo_stack.push(transaction);
6866        self.redo_stack.last()
6867    }
6868
6869    fn group(&mut self) -> Option<TransactionId> {
6870        let mut count = 0;
6871        let mut transactions = self.undo_stack.iter();
6872        if let Some(mut transaction) = transactions.next_back() {
6873            while let Some(prev_transaction) = transactions.next_back() {
6874                if !prev_transaction.suppress_grouping
6875                    && transaction.first_edit_at - prev_transaction.last_edit_at
6876                        <= self.group_interval
6877                {
6878                    transaction = prev_transaction;
6879                    count += 1;
6880                } else {
6881                    break;
6882                }
6883            }
6884        }
6885        self.group_trailing(count)
6886    }
6887
6888    fn group_until(&mut self, transaction_id: TransactionId) {
6889        let mut count = 0;
6890        for transaction in self.undo_stack.iter().rev() {
6891            if transaction.id == transaction_id {
6892                self.group_trailing(count);
6893                break;
6894            } else if transaction.suppress_grouping {
6895                break;
6896            } else {
6897                count += 1;
6898            }
6899        }
6900    }
6901
6902    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6903        let new_len = self.undo_stack.len() - n;
6904        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6905        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6906            if let Some(transaction) = transactions_to_merge.last() {
6907                last_transaction.last_edit_at = transaction.last_edit_at;
6908            }
6909            for to_merge in transactions_to_merge {
6910                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6911                    last_transaction
6912                        .buffer_transactions
6913                        .entry(*buffer_id)
6914                        .or_insert(*transaction_id);
6915                }
6916            }
6917        }
6918
6919        self.undo_stack.truncate(new_len);
6920        self.undo_stack.last().map(|t| t.id)
6921    }
6922}
6923
6924impl Excerpt {
6925    fn new(
6926        id: ExcerptId,
6927        locator: Locator,
6928        buffer_id: BufferId,
6929        buffer: BufferSnapshot,
6930        range: ExcerptRange<text::Anchor>,
6931        has_trailing_newline: bool,
6932    ) -> Self {
6933        Excerpt {
6934            id,
6935            locator,
6936            max_buffer_row: range.context.end.to_point(&buffer).row,
6937            text_summary: buffer
6938                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6939            buffer_id,
6940            buffer,
6941            range,
6942            has_trailing_newline,
6943        }
6944    }
6945
6946    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6947        let content_start = self.range.context.start.to_offset(&self.buffer);
6948        let chunks_start = content_start + range.start;
6949        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6950
6951        let footer_height = if self.has_trailing_newline
6952            && range.start <= self.text_summary.len
6953            && range.end > self.text_summary.len
6954        {
6955            1
6956        } else {
6957            0
6958        };
6959
6960        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
6961
6962        ExcerptChunks {
6963            excerpt_id: self.id,
6964            content_chunks,
6965            footer_height,
6966        }
6967    }
6968
6969    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
6970        let content_start = self.range.context.start.to_offset(&self.buffer);
6971        let chunks_start = content_start + range.start;
6972        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6973        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
6974        excerpt_chunks.footer_height = if self.has_trailing_newline
6975            && range.start <= self.text_summary.len
6976            && range.end > self.text_summary.len
6977        {
6978            1
6979        } else {
6980            0
6981        };
6982    }
6983
6984    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
6985        if text_anchor
6986            .cmp(&self.range.context.start, &self.buffer)
6987            .is_lt()
6988        {
6989            self.range.context.start
6990        } else if text_anchor
6991            .cmp(&self.range.context.end, &self.buffer)
6992            .is_gt()
6993        {
6994            self.range.context.end
6995        } else {
6996            text_anchor
6997        }
6998    }
6999
7000    fn contains(&self, anchor: &Anchor) -> bool {
7001        (anchor.buffer_id == None || anchor.buffer_id == Some(self.buffer_id))
7002            && self
7003                .range
7004                .context
7005                .start
7006                .cmp(&anchor.text_anchor, &self.buffer)
7007                .is_le()
7008            && self
7009                .range
7010                .context
7011                .end
7012                .cmp(&anchor.text_anchor, &self.buffer)
7013                .is_ge()
7014    }
7015
7016    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7017    fn buffer_start_offset(&self) -> usize {
7018        self.range.context.start.to_offset(&self.buffer)
7019    }
7020
7021    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7022    fn buffer_end_offset(&self) -> usize {
7023        self.buffer_start_offset() + self.text_summary.len
7024    }
7025}
7026
7027impl<'a> MultiBufferExcerpt<'a> {
7028    pub fn id(&self) -> ExcerptId {
7029        self.excerpt.id
7030    }
7031
7032    pub fn buffer_id(&self) -> BufferId {
7033        self.excerpt.buffer_id
7034    }
7035
7036    pub fn start_anchor(&self) -> Anchor {
7037        Anchor::in_buffer(
7038            self.excerpt.id,
7039            self.excerpt.buffer_id,
7040            self.excerpt.range.context.start,
7041        )
7042    }
7043
7044    pub fn end_anchor(&self) -> Anchor {
7045        Anchor::in_buffer(
7046            self.excerpt.id,
7047            self.excerpt.buffer_id,
7048            self.excerpt.range.context.end,
7049        )
7050    }
7051
7052    pub fn buffer(&self) -> &'a BufferSnapshot {
7053        &self.excerpt.buffer
7054    }
7055
7056    pub fn buffer_range(&self) -> Range<usize> {
7057        self.buffer_offset
7058            ..self
7059                .excerpt
7060                .range
7061                .context
7062                .end
7063                .to_offset(&self.excerpt.buffer.text)
7064    }
7065
7066    pub fn start_offset(&self) -> usize {
7067        self.offset
7068    }
7069
7070    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7071    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7072        self.map_range_to_buffer(offset..offset).start
7073    }
7074
7075    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7076    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7077        self.diff_transforms
7078            .seek(&OutputDimension(range.start), Bias::Right);
7079        let start = self.map_offset_to_buffer_internal(range.start);
7080        let end = if range.end > range.start {
7081            self.diff_transforms
7082                .seek_forward(&OutputDimension(range.end), Bias::Right);
7083            self.map_offset_to_buffer_internal(range.end)
7084        } else {
7085            start
7086        };
7087        start..end
7088    }
7089
7090    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7091        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7092        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7093            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7094        };
7095        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7096        self.buffer_offset + offset_in_excerpt
7097    }
7098
7099    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7100    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7101        self.map_range_from_buffer(buffer_offset..buffer_offset)
7102            .start
7103    }
7104
7105    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7106    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7107        if buffer_range.start < self.buffer_offset {
7108            log::warn!(
7109                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7110            );
7111            return buffer_range;
7112        }
7113        let overshoot = buffer_range.start - self.buffer_offset;
7114        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7115        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7116        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7117            log::warn!(
7118                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7119            );
7120            return buffer_range;
7121        }
7122        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7123        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7124
7125        let end = if buffer_range.end > buffer_range.start {
7126            let overshoot = buffer_range.end - self.buffer_offset;
7127            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7128            self.diff_transforms
7129                .seek_forward(&excerpt_offset, Bias::Right);
7130            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7131            self.diff_transforms.start().output_dimension.0 + overshoot
7132        } else {
7133            start
7134        };
7135
7136        start..end
7137    }
7138
7139    /// Returns true if the entirety of the given range is in the buffer's excerpt
7140    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7141        range.start >= self.excerpt.buffer_start_offset()
7142            && range.end <= self.excerpt.buffer_end_offset()
7143    }
7144
7145    pub fn max_buffer_row(&self) -> u32 {
7146        self.excerpt.max_buffer_row
7147    }
7148}
7149
7150impl ExcerptId {
7151    pub fn min() -> Self {
7152        Self(0)
7153    }
7154
7155    pub fn max() -> Self {
7156        Self(u32::MAX)
7157    }
7158
7159    pub fn to_proto(self) -> u64 {
7160        self.0 as _
7161    }
7162
7163    pub fn from_proto(proto: u64) -> Self {
7164        Self(proto as _)
7165    }
7166
7167    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7168        let a = snapshot.excerpt_locator_for_id(*self);
7169        let b = snapshot.excerpt_locator_for_id(*other);
7170        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7171    }
7172}
7173
7174impl From<ExcerptId> for usize {
7175    fn from(val: ExcerptId) -> Self {
7176        val.0 as usize
7177    }
7178}
7179
7180impl fmt::Debug for Excerpt {
7181    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7182        f.debug_struct("Excerpt")
7183            .field("id", &self.id)
7184            .field("locator", &self.locator)
7185            .field("buffer_id", &self.buffer_id)
7186            .field("range", &self.range)
7187            .field("text_summary", &self.text_summary)
7188            .field("has_trailing_newline", &self.has_trailing_newline)
7189            .finish()
7190    }
7191}
7192
7193impl sum_tree::Item for Excerpt {
7194    type Summary = ExcerptSummary;
7195
7196    fn summary(&self, _cx: ()) -> Self::Summary {
7197        let mut text = self.text_summary;
7198        if self.has_trailing_newline {
7199            text += TextSummary::from("\n");
7200        }
7201        ExcerptSummary {
7202            excerpt_id: self.id,
7203            excerpt_locator: self.locator.clone(),
7204            widest_line_number: self.max_buffer_row,
7205            text,
7206        }
7207    }
7208}
7209
7210impl sum_tree::Item for ExcerptIdMapping {
7211    type Summary = ExcerptId;
7212
7213    fn summary(&self, _cx: ()) -> Self::Summary {
7214        self.id
7215    }
7216}
7217
7218impl sum_tree::KeyedItem for ExcerptIdMapping {
7219    type Key = ExcerptId;
7220
7221    fn key(&self) -> Self::Key {
7222        self.id
7223    }
7224}
7225
7226impl DiffTransform {
7227    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7228        match self {
7229            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7230            DiffTransform::BufferContent {
7231                inserted_hunk_info, ..
7232            } => *inserted_hunk_info,
7233        }
7234    }
7235}
7236
7237impl sum_tree::Item for DiffTransform {
7238    type Summary = DiffTransformSummary;
7239
7240    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7241        match self {
7242            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7243                input: *summary,
7244                output: *summary,
7245            },
7246            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7247                input: TextSummary::default(),
7248                output: *summary,
7249            },
7250        }
7251    }
7252}
7253
7254impl DiffTransformSummary {
7255    fn excerpt_len(&self) -> ExcerptOffset {
7256        ExcerptOffset::new(self.input.len)
7257    }
7258}
7259
7260impl sum_tree::ContextLessSummary for DiffTransformSummary {
7261    fn zero() -> Self {
7262        DiffTransformSummary {
7263            input: TextSummary::default(),
7264            output: TextSummary::default(),
7265        }
7266    }
7267
7268    fn add_summary(&mut self, other: &Self) {
7269        self.input += other.input;
7270        self.output += other.output;
7271    }
7272}
7273
7274impl sum_tree::ContextLessSummary for ExcerptId {
7275    fn zero() -> Self {
7276        Self(0)
7277    }
7278
7279    fn add_summary(&mut self, summary: &Self) {
7280        *self = cmp::max(*self, *summary);
7281    }
7282}
7283
7284impl sum_tree::ContextLessSummary for ExcerptSummary {
7285    fn zero() -> Self {
7286        Self::default()
7287    }
7288
7289    fn add_summary(&mut self, summary: &Self) {
7290        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7291        self.excerpt_locator = summary.excerpt_locator.clone();
7292        Summary::add_summary(&mut self.text, &summary.text, ());
7293        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7294    }
7295}
7296
7297impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7298    fn zero(_cx: ()) -> Self {
7299        Default::default()
7300    }
7301
7302    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7303        self.value += summary.text.len;
7304    }
7305}
7306
7307impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7308    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7309        Ord::cmp(&self.value, &cursor_location.text.len)
7310    }
7311}
7312
7313impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7314    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
7315        Ord::cmp(&Some(self), cursor_location)
7316    }
7317}
7318
7319impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7320    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7321        Ord::cmp(self, &cursor_location.excerpt_locator)
7322    }
7323}
7324
7325impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7326    fn zero(_cx: ()) -> Self {
7327        Default::default()
7328    }
7329
7330    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7331        self.value += summary.text.lines;
7332    }
7333}
7334
7335impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7336    for ExcerptDimension<D>
7337{
7338    fn zero(_: ()) -> Self {
7339        ExcerptDimension(D::default())
7340    }
7341
7342    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7343        self.0.add_assign(&D::from_text_summary(&summary.text))
7344    }
7345}
7346
7347impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7348    fn zero(_cx: ()) -> Self {
7349        Default::default()
7350    }
7351
7352    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7353        *self = Some(&summary.excerpt_locator);
7354    }
7355}
7356
7357impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7358    fn zero(_cx: ()) -> Self {
7359        Default::default()
7360    }
7361
7362    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7363        *self = Some(summary.excerpt_id);
7364    }
7365}
7366
7367#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7368struct ExcerptDimension<T>(T);
7369
7370#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7371struct OutputDimension<T>(T);
7372
7373impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7374    fn zero(_: ()) -> Self {
7375        ExcerptOffset::new(0)
7376    }
7377
7378    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7379        self.value += summary.input.len;
7380    }
7381}
7382
7383impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7384    fn zero(_: ()) -> Self {
7385        ExcerptPoint::new(0, 0)
7386    }
7387
7388    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7389        self.value += summary.input.lines;
7390    }
7391}
7392
7393impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7394    for ExcerptDimension<D>
7395{
7396    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
7397        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7398    }
7399}
7400
7401impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7402    for ExcerptDimension<D>
7403{
7404    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7405        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7406    }
7407}
7408
7409impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7410    fn zero(_: ()) -> Self {
7411        ExcerptDimension(D::default())
7412    }
7413
7414    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7415        self.0.add_assign(&D::from_text_summary(&summary.input))
7416    }
7417}
7418
7419impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7420    for OutputDimension<D>
7421{
7422    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7423        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7424    }
7425}
7426
7427impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7428    fn zero(_: ()) -> Self {
7429        OutputDimension(D::default())
7430    }
7431
7432    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7433        self.0.add_assign(&D::from_text_summary(&summary.output))
7434    }
7435}
7436
7437impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7438    fn zero(_: ()) -> Self {
7439        TextSummary::default()
7440    }
7441
7442    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7443        *self += summary.output
7444    }
7445}
7446
7447impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7448    fn zero(_: ()) -> Self {
7449        0
7450    }
7451
7452    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7453        *self += summary.output.len
7454    }
7455}
7456
7457impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7458    fn zero(_: ()) -> Self {
7459        Point::new(0, 0)
7460    }
7461
7462    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7463        *self += summary.output.lines
7464    }
7465}
7466
7467impl MultiBufferRows<'_> {
7468    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7469        self.point = Point::new(row, 0);
7470        self.cursor.seek(&self.point);
7471    }
7472}
7473
7474impl Iterator for MultiBufferRows<'_> {
7475    type Item = RowInfo;
7476
7477    fn next(&mut self) -> Option<Self::Item> {
7478        if self.is_empty && self.point.row == 0 {
7479            self.point += Point::new(1, 0);
7480            return Some(RowInfo {
7481                buffer_id: None,
7482                buffer_row: Some(0),
7483                multibuffer_row: Some(MultiBufferRow(0)),
7484                diff_status: None,
7485                expand_info: None,
7486            });
7487        }
7488
7489        let mut region = self.cursor.region()?;
7490        while self.point >= region.range.end {
7491            self.cursor.next();
7492            if let Some(next_region) = self.cursor.region() {
7493                region = next_region;
7494            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7495                let multibuffer_row = MultiBufferRow(self.point.row);
7496                let last_excerpt = self
7497                    .cursor
7498                    .excerpts
7499                    .item()
7500                    .or(self.cursor.excerpts.prev_item())?;
7501                let last_row = last_excerpt
7502                    .range
7503                    .context
7504                    .end
7505                    .to_point(&last_excerpt.buffer)
7506                    .row;
7507
7508                let first_row = last_excerpt
7509                    .range
7510                    .context
7511                    .start
7512                    .to_point(&last_excerpt.buffer)
7513                    .row;
7514
7515                let expand_info = if self.is_singleton {
7516                    None
7517                } else {
7518                    let needs_expand_up = first_row == last_row
7519                        && last_row > 0
7520                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7521                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
7522
7523                    if needs_expand_up && needs_expand_down {
7524                        Some(ExpandExcerptDirection::UpAndDown)
7525                    } else if needs_expand_up {
7526                        Some(ExpandExcerptDirection::Up)
7527                    } else if needs_expand_down {
7528                        Some(ExpandExcerptDirection::Down)
7529                    } else {
7530                        None
7531                    }
7532                    .map(|direction| ExpandInfo {
7533                        direction,
7534                        excerpt_id: last_excerpt.id,
7535                    })
7536                };
7537                self.point += Point::new(1, 0);
7538                return Some(RowInfo {
7539                    buffer_id: Some(last_excerpt.buffer_id),
7540                    buffer_row: Some(last_row),
7541                    multibuffer_row: Some(multibuffer_row),
7542                    diff_status: None,
7543                    expand_info,
7544                });
7545            } else {
7546                return None;
7547            };
7548        }
7549
7550        let overshoot = self.point - region.range.start;
7551        let buffer_point = region.buffer_range.start + overshoot;
7552        let expand_info = if self.is_singleton {
7553            None
7554        } else {
7555            let needs_expand_up = self.point.row == region.range.start.row
7556                && self.cursor.is_at_start_of_excerpt()
7557                && buffer_point.row > 0;
7558            let needs_expand_down = (region.excerpt.has_trailing_newline
7559                && self.point.row + 1 == region.range.end.row
7560                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7561                && self.cursor.is_at_end_of_excerpt()
7562                && buffer_point.row < region.buffer.max_point().row;
7563
7564            if needs_expand_up && needs_expand_down {
7565                Some(ExpandExcerptDirection::UpAndDown)
7566            } else if needs_expand_up {
7567                Some(ExpandExcerptDirection::Up)
7568            } else if needs_expand_down {
7569                Some(ExpandExcerptDirection::Down)
7570            } else {
7571                None
7572            }
7573            .map(|direction| ExpandInfo {
7574                direction,
7575                excerpt_id: region.excerpt.id,
7576            })
7577        };
7578
7579        let result = Some(RowInfo {
7580            buffer_id: Some(region.buffer.remote_id()),
7581            buffer_row: Some(buffer_point.row),
7582            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7583            diff_status: region
7584                .diff_hunk_status
7585                .filter(|_| self.point < region.range.end),
7586            expand_info,
7587        });
7588        self.point += Point::new(1, 0);
7589        result
7590    }
7591}
7592
7593impl<'a> MultiBufferChunks<'a> {
7594    pub fn offset(&self) -> usize {
7595        self.range.start
7596    }
7597
7598    pub fn seek(&mut self, range: Range<usize>) {
7599        self.diff_transforms.seek(&range.end, Bias::Right);
7600        let mut excerpt_end = self.diff_transforms.start().1;
7601        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7602            let overshoot = range.end - self.diff_transforms.start().0;
7603            excerpt_end.value += overshoot;
7604        }
7605
7606        self.diff_transforms.seek(&range.start, Bias::Right);
7607        let mut excerpt_start = self.diff_transforms.start().1;
7608        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7609            let overshoot = range.start - self.diff_transforms.start().0;
7610            excerpt_start.value += overshoot;
7611        }
7612
7613        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7614        self.buffer_chunk.take();
7615        self.range = range;
7616    }
7617
7618    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7619        self.excerpt_offset_range = new_range.clone();
7620        self.excerpts.seek(&new_range.start, Bias::Right);
7621        if let Some(excerpt) = self.excerpts.item() {
7622            let excerpt_start = *self.excerpts.start();
7623            if let Some(excerpt_chunks) = self
7624                .excerpt_chunks
7625                .as_mut()
7626                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7627            {
7628                excerpt.seek_chunks(
7629                    excerpt_chunks,
7630                    (self.excerpt_offset_range.start - excerpt_start).value
7631                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7632                );
7633            } else {
7634                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7635                    (self.excerpt_offset_range.start - excerpt_start).value
7636                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7637                    self.language_aware,
7638                ));
7639            }
7640        } else {
7641            self.excerpt_chunks = None;
7642        }
7643    }
7644
7645    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7646        loop {
7647            if self.excerpt_offset_range.is_empty() {
7648                return None;
7649            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7650                self.excerpt_offset_range.start.value += chunk.text.len();
7651                return Some(chunk);
7652            } else {
7653                self.excerpts.next();
7654                let excerpt = self.excerpts.item()?;
7655                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7656                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7657                    self.language_aware,
7658                ));
7659            }
7660        }
7661    }
7662}
7663
7664impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7665    type Item = &'a str;
7666
7667    fn next(&mut self) -> Option<Self::Item> {
7668        let mut region = self.cursor.region()?;
7669        if self.offset == region.range.start {
7670            self.cursor.prev();
7671            region = self.cursor.region()?;
7672            let start_overshoot = self.start.saturating_sub(region.range.start);
7673            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7674                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7675            ));
7676        }
7677
7678        if self.offset == region.range.end && region.has_trailing_newline {
7679            self.offset -= 1;
7680            Some("\n")
7681        } else {
7682            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7683            self.offset -= chunk.len();
7684            Some(chunk)
7685        }
7686    }
7687}
7688
7689impl<'a> Iterator for MultiBufferChunks<'a> {
7690    type Item = Chunk<'a>;
7691
7692    fn next(&mut self) -> Option<Chunk<'a>> {
7693        if self.range.start >= self.range.end {
7694            return None;
7695        }
7696        if self.range.start == self.diff_transforms.end().0 {
7697            self.diff_transforms.next();
7698        }
7699
7700        let diff_transform_start = self.diff_transforms.start().0;
7701        let diff_transform_end = self.diff_transforms.end().0;
7702        debug_assert!(self.range.start < diff_transform_end);
7703
7704        let diff_transform = self.diff_transforms.item()?;
7705        match diff_transform {
7706            DiffTransform::BufferContent { .. } => {
7707                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7708                    chunk
7709                } else {
7710                    let chunk = self.next_excerpt_chunk().unwrap();
7711                    self.buffer_chunk.insert(chunk)
7712                };
7713
7714                let chunk_end = self.range.start + chunk.text.len();
7715                let diff_transform_end = diff_transform_end.min(self.range.end);
7716
7717                if diff_transform_end < chunk_end {
7718                    let split_idx = diff_transform_end - self.range.start;
7719                    let (before, after) = chunk.text.split_at(split_idx);
7720                    self.range.start = diff_transform_end;
7721                    let mask = (1 << split_idx) - 1;
7722                    let chars = chunk.chars & mask;
7723                    let tabs = chunk.tabs & mask;
7724
7725                    chunk.text = after;
7726                    chunk.chars = chunk.chars >> split_idx;
7727                    chunk.tabs = chunk.tabs >> split_idx;
7728
7729                    Some(Chunk {
7730                        text: before,
7731                        chars,
7732                        tabs,
7733                        ..chunk.clone()
7734                    })
7735                } else {
7736                    self.range.start = chunk_end;
7737                    self.buffer_chunk.take()
7738                }
7739            }
7740            DiffTransform::DeletedHunk {
7741                buffer_id,
7742                base_text_byte_range,
7743                has_trailing_newline,
7744                ..
7745            } => {
7746                let base_text_start =
7747                    base_text_byte_range.start + self.range.start - diff_transform_start;
7748                let base_text_end =
7749                    base_text_byte_range.start + self.range.end - diff_transform_start;
7750                let base_text_end = base_text_end.min(base_text_byte_range.end);
7751
7752                let mut chunks = if let Some((_, mut chunks)) = self
7753                    .diff_base_chunks
7754                    .take()
7755                    .filter(|(id, _)| id == buffer_id)
7756                {
7757                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7758                    {
7759                        chunks.seek(base_text_start..base_text_end);
7760                    }
7761                    chunks
7762                } else {
7763                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7764                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7765                };
7766
7767                let chunk = if let Some(chunk) = chunks.next() {
7768                    self.range.start += chunk.text.len();
7769                    self.diff_base_chunks = Some((*buffer_id, chunks));
7770                    chunk
7771                } else {
7772                    debug_assert!(has_trailing_newline);
7773                    self.range.start += "\n".len();
7774                    Chunk {
7775                        text: "\n",
7776                        chars: 1u128,
7777                        ..Default::default()
7778                    }
7779                };
7780                Some(chunk)
7781            }
7782        }
7783    }
7784}
7785
7786impl MultiBufferBytes<'_> {
7787    fn consume(&mut self, len: usize) {
7788        self.range.start += len;
7789        self.chunk = &self.chunk[len..];
7790
7791        if !self.range.is_empty() && self.chunk.is_empty() {
7792            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7793                self.chunk = chunk;
7794            } else if self.has_trailing_newline {
7795                self.has_trailing_newline = false;
7796                self.chunk = b"\n";
7797            } else {
7798                self.cursor.next();
7799                if let Some(region) = self.cursor.region() {
7800                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7801                        region.buffer_range.start
7802                            ..(region.buffer_range.start + self.range.end - region.range.start)
7803                                .min(region.buffer_range.end),
7804                    );
7805                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7806                    self.excerpt_bytes = Some(excerpt_bytes);
7807                    self.has_trailing_newline =
7808                        region.has_trailing_newline && self.range.end >= region.range.end;
7809                    if self.chunk.is_empty() && self.has_trailing_newline {
7810                        self.has_trailing_newline = false;
7811                        self.chunk = b"\n";
7812                    }
7813                }
7814            }
7815        }
7816    }
7817}
7818
7819impl<'a> Iterator for MultiBufferBytes<'a> {
7820    type Item = &'a [u8];
7821
7822    fn next(&mut self) -> Option<Self::Item> {
7823        let chunk = self.chunk;
7824        if chunk.is_empty() {
7825            None
7826        } else {
7827            self.consume(chunk.len());
7828            Some(chunk)
7829        }
7830    }
7831}
7832
7833impl io::Read for MultiBufferBytes<'_> {
7834    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7835        let len = cmp::min(buf.len(), self.chunk.len());
7836        buf[..len].copy_from_slice(&self.chunk[..len]);
7837        if len > 0 {
7838            self.consume(len);
7839        }
7840        Ok(len)
7841    }
7842}
7843
7844impl io::Read for ReversedMultiBufferBytes<'_> {
7845    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7846        let len = cmp::min(buf.len(), self.chunk.len());
7847        buf[..len].copy_from_slice(&self.chunk[..len]);
7848        buf[..len].reverse();
7849        if len > 0 {
7850            self.range.end -= len;
7851            self.chunk = &self.chunk[..self.chunk.len() - len];
7852            if !self.range.is_empty()
7853                && self.chunk.is_empty()
7854                && let Some(chunk) = self.chunks.next()
7855            {
7856                self.chunk = chunk.as_bytes();
7857            }
7858        }
7859        Ok(len)
7860    }
7861}
7862
7863impl<'a> Iterator for ExcerptChunks<'a> {
7864    type Item = Chunk<'a>;
7865
7866    fn next(&mut self) -> Option<Self::Item> {
7867        if let Some(chunk) = self.content_chunks.next() {
7868            return Some(chunk);
7869        }
7870
7871        if self.footer_height > 0 {
7872            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7873            let chars = (1 << self.footer_height) - 1;
7874            self.footer_height = 0;
7875            return Some(Chunk {
7876                text,
7877                chars,
7878                ..Default::default()
7879            });
7880        }
7881
7882        None
7883    }
7884}
7885
7886impl ToOffset for Point {
7887    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7888        snapshot.point_to_offset(*self)
7889    }
7890}
7891
7892impl ToOffset for usize {
7893    #[track_caller]
7894    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7895        assert!(
7896            *self <= snapshot.len(),
7897            "offset {} is greater than the snapshot.len() {}",
7898            *self,
7899            snapshot.len(),
7900        );
7901        *self
7902    }
7903}
7904
7905impl ToOffset for OffsetUtf16 {
7906    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7907        snapshot.offset_utf16_to_offset(*self)
7908    }
7909}
7910
7911impl ToOffset for PointUtf16 {
7912    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7913        snapshot.point_utf16_to_offset(*self)
7914    }
7915}
7916
7917impl ToOffsetUtf16 for OffsetUtf16 {
7918    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7919        *self
7920    }
7921}
7922
7923impl ToOffsetUtf16 for usize {
7924    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7925        snapshot.offset_to_offset_utf16(*self)
7926    }
7927}
7928
7929impl ToPoint for usize {
7930    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7931        snapshot.offset_to_point(*self)
7932    }
7933}
7934
7935impl ToPoint for Point {
7936    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7937        *self
7938    }
7939}
7940
7941impl ToPointUtf16 for usize {
7942    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7943        snapshot.offset_to_point_utf16(*self)
7944    }
7945}
7946
7947impl ToPointUtf16 for Point {
7948    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7949        snapshot.point_to_point_utf16(*self)
7950    }
7951}
7952
7953impl ToPointUtf16 for PointUtf16 {
7954    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7955        *self
7956    }
7957}
7958
7959impl From<ExcerptId> for EntityId {
7960    fn from(id: ExcerptId) -> Self {
7961        EntityId::from(id.0 as u64)
7962    }
7963}
7964
7965#[cfg(debug_assertions)]
7966pub mod debug {
7967    use super::*;
7968
7969    pub trait ToMultiBufferDebugRanges {
7970        fn to_multi_buffer_debug_ranges(&self, snapshot: &MultiBufferSnapshot)
7971        -> Vec<Range<usize>>;
7972    }
7973
7974    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
7975        fn to_multi_buffer_debug_ranges(
7976            &self,
7977            snapshot: &MultiBufferSnapshot,
7978        ) -> Vec<Range<usize>> {
7979            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
7980        }
7981    }
7982
7983    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
7984        fn to_multi_buffer_debug_ranges(
7985            &self,
7986            snapshot: &MultiBufferSnapshot,
7987        ) -> Vec<Range<usize>> {
7988            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
7989                .to_multi_buffer_debug_ranges(snapshot)
7990        }
7991    }
7992
7993    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
7994        fn to_multi_buffer_debug_ranges(
7995            &self,
7996            snapshot: &MultiBufferSnapshot,
7997        ) -> Vec<Range<usize>> {
7998            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
7999        }
8000    }
8001
8002    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8003        fn to_multi_buffer_debug_ranges(
8004            &self,
8005            snapshot: &MultiBufferSnapshot,
8006        ) -> Vec<Range<usize>> {
8007            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8008        }
8009    }
8010
8011    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8012        fn to_multi_buffer_debug_ranges(
8013            &self,
8014            snapshot: &MultiBufferSnapshot,
8015        ) -> Vec<Range<usize>> {
8016            self.iter()
8017                .map(|item| {
8018                    let offset = item.to_offset(snapshot);
8019                    offset..offset
8020                })
8021                .collect()
8022        }
8023    }
8024
8025    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8026        fn to_multi_buffer_debug_ranges(
8027            &self,
8028            snapshot: &MultiBufferSnapshot,
8029        ) -> Vec<Range<usize>> {
8030            self.iter()
8031                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8032                .collect()
8033        }
8034    }
8035}