multi_buffer.rs

   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        singleton_buffer_edited: bool,
 103        edited_buffer: Option<Entity<Buffer>>,
 104    },
 105    TransactionUndone {
 106        transaction_id: TransactionId,
 107    },
 108    Reloaded,
 109    LanguageChanged(BufferId),
 110    Reparsed(BufferId),
 111    Saved,
 112    FileHandleChanged,
 113    DirtyChanged,
 114    DiagnosticsUpdated,
 115    BufferDiffChanged,
 116}
 117
 118/// A diff hunk, representing a range of consequent lines in a multibuffer.
 119#[derive(Debug, Clone, PartialEq, Eq)]
 120pub struct MultiBufferDiffHunk {
 121    /// The row range in the multibuffer where this diff hunk appears.
 122    pub row_range: Range<MultiBufferRow>,
 123    /// The buffer ID that this hunk belongs to.
 124    pub buffer_id: BufferId,
 125    /// The range of the underlying buffer that this hunk corresponds to.
 126    pub buffer_range: Range<text::Anchor>,
 127    /// The excerpt that contains the diff hunk.
 128    pub excerpt_id: ExcerptId,
 129    /// The range within the buffer's diff base that this hunk corresponds to.
 130    pub diff_base_byte_range: Range<usize>,
 131    /// Whether or not this hunk also appears in the 'secondary diff'.
 132    pub secondary_status: DiffHunkSecondaryStatus,
 133}
 134
 135impl MultiBufferDiffHunk {
 136    pub fn status(&self) -> DiffHunkStatus {
 137        let kind = if self.buffer_range.start == self.buffer_range.end {
 138            DiffHunkStatusKind::Deleted
 139        } else if self.diff_base_byte_range.is_empty() {
 140            DiffHunkStatusKind::Added
 141        } else {
 142            DiffHunkStatusKind::Modified
 143        };
 144        DiffHunkStatus {
 145            kind,
 146            secondary: self.secondary_status,
 147        }
 148    }
 149
 150    pub fn is_created_file(&self) -> bool {
 151        self.diff_base_byte_range == (0..0)
 152            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 153    }
 154
 155    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 156        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 157        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 158        start..end
 159    }
 160}
 161
 162#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 163pub struct PathKey {
 164    namespace: Option<u64>,
 165    path: Arc<RelPath>,
 166}
 167
 168impl PathKey {
 169    pub fn namespaced(namespace: u64, path: Arc<RelPath>) -> Self {
 170        Self {
 171            namespace: Some(namespace),
 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::namespaced(file.worktree_id(cx).to_proto(), file.path().clone())
 179        } else {
 180            Self {
 181                namespace: 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            singleton_buffer_edited: false,
2036            edited_buffer: None,
2037        });
2038        cx.emit(Event::ExcerptsAdded {
2039            buffer,
2040            predecessor: prev_excerpt_id,
2041            excerpts,
2042        });
2043        cx.notify();
2044    }
2045
2046    pub fn clear(&mut self, cx: &mut Context<Self>) {
2047        self.sync(cx);
2048        let ids = self.excerpt_ids();
2049        let removed_buffer_ids = self
2050            .buffers
2051            .borrow_mut()
2052            .drain()
2053            .map(|(id, _)| id)
2054            .collect();
2055        self.excerpts_by_path.clear();
2056        self.paths_by_excerpt.clear();
2057        let mut snapshot = self.snapshot.borrow_mut();
2058        let start = ExcerptOffset::new(0);
2059        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2060        snapshot.excerpts = Default::default();
2061        snapshot.trailing_excerpt_update_count += 1;
2062        snapshot.is_dirty = false;
2063        snapshot.has_deleted_file = false;
2064        snapshot.has_conflict = false;
2065        snapshot.replaced_excerpts.clear();
2066
2067        self.sync_diff_transforms(
2068            &mut snapshot,
2069            vec![Edit {
2070                old: start..prev_len,
2071                new: start..start,
2072            }],
2073            DiffChangeKind::BufferEdited,
2074        );
2075        cx.emit(Event::Edited {
2076            singleton_buffer_edited: false,
2077            edited_buffer: None,
2078        });
2079        cx.emit(Event::ExcerptsRemoved {
2080            ids,
2081            removed_buffer_ids,
2082        });
2083        cx.notify();
2084    }
2085
2086    pub fn excerpts_for_buffer(
2087        &self,
2088        buffer_id: BufferId,
2089        cx: &App,
2090    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2091        let mut excerpts = Vec::new();
2092        let snapshot = self.read(cx);
2093        let buffers = self.buffers.borrow();
2094        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
2095        if let Some(locators) = buffers.get(&buffer_id).map(|state| &state.excerpts) {
2096            for locator in locators {
2097                cursor.seek_forward(&Some(locator), Bias::Left);
2098                if let Some(excerpt) = cursor.item()
2099                    && excerpt.locator == *locator
2100                {
2101                    excerpts.push((excerpt.id, excerpt.range.clone()));
2102                }
2103            }
2104        }
2105
2106        excerpts
2107    }
2108
2109    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2110        let snapshot = self.read(cx);
2111        let buffers = self.buffers.borrow();
2112        let mut excerpts = snapshot
2113            .excerpts
2114            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
2115        let mut diff_transforms = snapshot
2116            .diff_transforms
2117            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
2118        diff_transforms.next();
2119        let locators = buffers
2120            .get(&buffer_id)
2121            .into_iter()
2122            .flat_map(|state| &state.excerpts);
2123        let mut result = Vec::new();
2124        for locator in locators {
2125            excerpts.seek_forward(&Some(locator), Bias::Left);
2126            if let Some(excerpt) = excerpts.item()
2127                && excerpt.locator == *locator
2128            {
2129                let excerpt_start = excerpts.start().1.clone();
2130                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2131
2132                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2133                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2134                let start = diff_transforms.start().1.0 + overshoot;
2135
2136                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2137                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2138                let end = diff_transforms.start().1.0 + overshoot;
2139
2140                result.push(start..end)
2141            }
2142        }
2143        result
2144    }
2145
2146    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2147        self.snapshot
2148            .borrow()
2149            .excerpts
2150            .iter()
2151            .map(|entry| entry.buffer_id)
2152            .collect()
2153    }
2154
2155    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2156        self.snapshot
2157            .borrow()
2158            .excerpts
2159            .iter()
2160            .map(|entry| entry.id)
2161            .collect()
2162    }
2163
2164    pub fn excerpt_containing(
2165        &self,
2166        position: impl ToOffset,
2167        cx: &App,
2168    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2169        let snapshot = self.read(cx);
2170        let offset = position.to_offset(&snapshot);
2171
2172        let mut cursor = snapshot.cursor::<usize>();
2173        cursor.seek(&offset);
2174        cursor
2175            .excerpt()
2176            .or_else(|| snapshot.excerpts.last())
2177            .map(|excerpt| {
2178                (
2179                    excerpt.id,
2180                    self.buffers
2181                        .borrow()
2182                        .get(&excerpt.buffer_id)
2183                        .unwrap()
2184                        .buffer
2185                        .clone(),
2186                    excerpt.range.context.clone(),
2187                )
2188            })
2189    }
2190
2191    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2192        if let Some(buffer_id) = anchor.buffer_id {
2193            self.buffer(buffer_id)
2194        } else {
2195            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2196            Some(buffer)
2197        }
2198    }
2199
2200    // If point is at the end of the buffer, the last excerpt is returned
2201    pub fn point_to_buffer_offset<T: ToOffset>(
2202        &self,
2203        point: T,
2204        cx: &App,
2205    ) -> Option<(Entity<Buffer>, usize)> {
2206        let snapshot = self.read(cx);
2207        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2208        Some((
2209            self.buffers
2210                .borrow()
2211                .get(&buffer.remote_id())?
2212                .buffer
2213                .clone(),
2214            offset,
2215        ))
2216    }
2217
2218    // If point is at the end of the buffer, the last excerpt is returned
2219    pub fn point_to_buffer_point<T: ToPoint>(
2220        &self,
2221        point: T,
2222        cx: &App,
2223    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2224        let snapshot = self.read(cx);
2225        let (buffer, point, is_main_buffer) =
2226            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2227        Some((
2228            self.buffers
2229                .borrow()
2230                .get(&buffer.remote_id())?
2231                .buffer
2232                .clone(),
2233            point,
2234            is_main_buffer,
2235        ))
2236    }
2237
2238    pub fn buffer_point_to_anchor(
2239        &self,
2240        buffer: &Entity<Buffer>,
2241        point: Point,
2242        cx: &App,
2243    ) -> Option<Anchor> {
2244        let mut found = None;
2245        let snapshot = buffer.read(cx).snapshot();
2246        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2247            let start = range.context.start.to_point(&snapshot);
2248            let end = range.context.end.to_point(&snapshot);
2249            if start <= point && point < end {
2250                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2251                break;
2252            }
2253            if point < start {
2254                found = Some((start, excerpt_id));
2255            }
2256            if point > end {
2257                found = Some((end, excerpt_id));
2258            }
2259        }
2260
2261        found.map(|(point, excerpt_id)| {
2262            let text_anchor = snapshot.anchor_after(point);
2263            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2264        })
2265    }
2266
2267    pub fn remove_excerpts(
2268        &mut self,
2269        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2270        cx: &mut Context<Self>,
2271    ) {
2272        self.sync(cx);
2273        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2274        if ids.is_empty() {
2275            return;
2276        }
2277
2278        let mut buffers = self.buffers.borrow_mut();
2279        let mut snapshot = self.snapshot.borrow_mut();
2280        let mut new_excerpts = SumTree::default();
2281        let mut cursor = snapshot
2282            .excerpts
2283            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2284        let mut edits = Vec::new();
2285        let mut excerpt_ids = ids.iter().copied().peekable();
2286        let mut removed_buffer_ids = Vec::new();
2287
2288        while let Some(excerpt_id) = excerpt_ids.next() {
2289            self.paths_by_excerpt.remove(&excerpt_id);
2290            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2291            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2292            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2293
2294            if let Some(mut excerpt) = cursor.item() {
2295                if excerpt.id != excerpt_id {
2296                    continue;
2297                }
2298                let mut old_start = cursor.start().1;
2299
2300                // Skip over the removed excerpt.
2301                'remove_excerpts: loop {
2302                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2303                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2304                        if buffer_state.excerpts.is_empty() {
2305                            log::debug!(
2306                                "removing buffer and diff for buffer {}",
2307                                excerpt.buffer_id
2308                            );
2309                            buffers.remove(&excerpt.buffer_id);
2310                            removed_buffer_ids.push(excerpt.buffer_id);
2311                        }
2312                    }
2313                    cursor.next();
2314
2315                    // Skip over any subsequent excerpts that are also removed.
2316                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2317                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2318                        if let Some(next_excerpt) = cursor.item()
2319                            && next_excerpt.locator == *next_locator
2320                        {
2321                            excerpt_ids.next();
2322                            excerpt = next_excerpt;
2323                            continue 'remove_excerpts;
2324                        }
2325                    }
2326
2327                    break;
2328                }
2329
2330                // When removing the last excerpt, remove the trailing newline from
2331                // the previous excerpt.
2332                if cursor.item().is_none() && old_start.value > 0 {
2333                    old_start.value -= 1;
2334                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2335                }
2336
2337                // Push an edit for the removal of this run of excerpts.
2338                let old_end = cursor.start().1;
2339                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2340                edits.push(Edit {
2341                    old: old_start..old_end,
2342                    new: new_start..new_start,
2343                });
2344            }
2345        }
2346        let suffix = cursor.suffix();
2347        let changed_trailing_excerpt = suffix.is_empty();
2348        new_excerpts.append(suffix, ());
2349        drop(cursor);
2350        snapshot.excerpts = new_excerpts;
2351        for buffer_id in &removed_buffer_ids {
2352            self.diffs.remove(buffer_id);
2353            snapshot.diffs.remove(buffer_id);
2354        }
2355
2356        if changed_trailing_excerpt {
2357            snapshot.trailing_excerpt_update_count += 1;
2358        }
2359
2360        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2361        self.buffer_changed_since_sync.replace(true);
2362        cx.emit(Event::Edited {
2363            singleton_buffer_edited: false,
2364            edited_buffer: None,
2365        });
2366        cx.emit(Event::ExcerptsRemoved {
2367            ids,
2368            removed_buffer_ids,
2369        });
2370        cx.notify();
2371    }
2372
2373    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2374        &self,
2375        anchors: Anchors,
2376        cx: &mut Context<Self>,
2377    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2378        let borrow = self.buffers.borrow();
2379        let mut error = None;
2380        let mut futures = Vec::new();
2381        for anchor in anchors {
2382            if let Some(buffer_id) = anchor.buffer_id {
2383                if let Some(buffer) = borrow.get(&buffer_id) {
2384                    buffer.buffer.update(cx, |buffer, _| {
2385                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2386                    });
2387                } else {
2388                    error = Some(anyhow!(
2389                        "buffer {buffer_id} is not part of this multi-buffer"
2390                    ));
2391                    break;
2392                }
2393            }
2394        }
2395        async move {
2396            if let Some(error) = error {
2397                Err(error)?;
2398            }
2399            for future in futures {
2400                future.await?;
2401            }
2402            Ok(())
2403        }
2404    }
2405
2406    pub fn text_anchor_for_position<T: ToOffset>(
2407        &self,
2408        position: T,
2409        cx: &App,
2410    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2411        let snapshot = self.read(cx);
2412        let anchor = snapshot.anchor_before(position);
2413        let buffer = self
2414            .buffers
2415            .borrow()
2416            .get(&anchor.buffer_id?)?
2417            .buffer
2418            .clone();
2419        Some((buffer, anchor.text_anchor))
2420    }
2421
2422    fn on_buffer_event(
2423        &mut self,
2424        buffer: Entity<Buffer>,
2425        event: &language::BufferEvent,
2426        cx: &mut Context<Self>,
2427    ) {
2428        use language::BufferEvent;
2429        cx.emit(match event {
2430            BufferEvent::Edited => Event::Edited {
2431                singleton_buffer_edited: true,
2432                edited_buffer: Some(buffer),
2433            },
2434            BufferEvent::DirtyChanged => Event::DirtyChanged,
2435            BufferEvent::Saved => Event::Saved,
2436            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2437            BufferEvent::Reloaded => Event::Reloaded,
2438            BufferEvent::LanguageChanged => Event::LanguageChanged(buffer.read(cx).remote_id()),
2439            BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2440            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2441            BufferEvent::CapabilityChanged => {
2442                self.capability = buffer.read(cx).capability();
2443                return;
2444            }
2445            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2446        });
2447    }
2448
2449    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2450        self.sync(cx);
2451        let mut snapshot = self.snapshot.borrow_mut();
2452        let diff = diff.read(cx);
2453        let buffer_id = diff.buffer_id;
2454        let diff = diff.snapshot(cx);
2455        snapshot.diffs.insert(buffer_id, diff);
2456    }
2457
2458    fn buffer_diff_changed(
2459        &mut self,
2460        diff: Entity<BufferDiff>,
2461        range: Range<text::Anchor>,
2462        cx: &mut Context<Self>,
2463    ) {
2464        self.sync(cx);
2465        self.buffer_changed_since_sync.replace(true);
2466
2467        let diff = diff.read(cx);
2468        let buffer_id = diff.buffer_id;
2469        let buffers = self.buffers.borrow();
2470        let Some(buffer_state) = buffers.get(&buffer_id) else {
2471            return;
2472        };
2473
2474        let buffer = buffer_state.buffer.read(cx);
2475        let diff_change_range = range.to_offset(buffer);
2476
2477        let new_diff = diff.snapshot(cx);
2478        let mut snapshot = self.snapshot.borrow_mut();
2479        let base_text_changed = snapshot
2480            .diffs
2481            .get(&buffer_id)
2482            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2483
2484        snapshot.diffs.insert(buffer_id, new_diff);
2485
2486        let mut excerpt_edits = Vec::new();
2487        for locator in &buffer_state.excerpts {
2488            let mut cursor = snapshot
2489                .excerpts
2490                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2491            cursor.seek_forward(&Some(locator), Bias::Left);
2492            if let Some(excerpt) = cursor.item()
2493                && excerpt.locator == *locator
2494            {
2495                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2496                if diff_change_range.end < excerpt_buffer_range.start
2497                    || diff_change_range.start > excerpt_buffer_range.end
2498                {
2499                    continue;
2500                }
2501                let excerpt_start = cursor.start().1;
2502                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2503                let diff_change_start_in_excerpt = ExcerptOffset::new(
2504                    diff_change_range
2505                        .start
2506                        .saturating_sub(excerpt_buffer_range.start),
2507                );
2508                let diff_change_end_in_excerpt = ExcerptOffset::new(
2509                    diff_change_range
2510                        .end
2511                        .saturating_sub(excerpt_buffer_range.start),
2512                );
2513                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2514                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2515                excerpt_edits.push(Edit {
2516                    old: edit_start..edit_end,
2517                    new: edit_start..edit_end,
2518                });
2519            }
2520        }
2521
2522        self.sync_diff_transforms(
2523            &mut snapshot,
2524            excerpt_edits,
2525            DiffChangeKind::DiffUpdated {
2526                base_changed: base_text_changed,
2527            },
2528        );
2529        cx.emit(Event::Edited {
2530            singleton_buffer_edited: false,
2531            edited_buffer: None,
2532        });
2533    }
2534
2535    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2536        self.buffers
2537            .borrow()
2538            .values()
2539            .map(|state| state.buffer.clone())
2540            .collect()
2541    }
2542
2543    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2544        self.buffers.borrow().keys().copied().collect()
2545    }
2546
2547    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2548        self.buffers
2549            .borrow()
2550            .get(&buffer_id)
2551            .map(|state| state.buffer.clone())
2552    }
2553
2554    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2555        self.point_to_buffer_offset(point, cx)
2556            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2557    }
2558
2559    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2560        let buffer_id = self
2561            .snapshot
2562            .borrow()
2563            .excerpts
2564            .first()
2565            .map(|excerpt| excerpt.buffer.remote_id());
2566        buffer_id
2567            .and_then(|buffer_id| self.buffer(buffer_id))
2568            .map(|buffer| {
2569                let buffer = buffer.read(cx);
2570                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2571            })
2572            .unwrap_or_else(move || self.language_settings_at(0, cx))
2573    }
2574
2575    pub fn language_settings_at<'a, T: ToOffset>(
2576        &'a self,
2577        point: T,
2578        cx: &'a App,
2579    ) -> Cow<'a, LanguageSettings> {
2580        let mut language = None;
2581        let mut file = None;
2582        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2583            let buffer = buffer.read(cx);
2584            language = buffer.language_at(offset);
2585            file = buffer.file();
2586        }
2587        language_settings(language.map(|l| l.name()), file, cx)
2588    }
2589
2590    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2591        self.buffers
2592            .borrow()
2593            .values()
2594            .for_each(|state| f(&state.buffer))
2595    }
2596
2597    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2598        if let Some(title) = self.title.as_ref() {
2599            return title.into();
2600        }
2601
2602        if let Some(buffer) = self.as_singleton() {
2603            let buffer = buffer.read(cx);
2604
2605            if let Some(file) = buffer.file() {
2606                return file.file_name(cx).into();
2607            }
2608
2609            if let Some(title) = self.buffer_content_title(buffer) {
2610                return title;
2611            }
2612        };
2613
2614        "untitled".into()
2615    }
2616
2617    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2618        let mut is_leading_whitespace = true;
2619        let mut count = 0;
2620        let mut prev_was_space = false;
2621        let mut title = String::new();
2622
2623        for ch in buffer.snapshot().chars() {
2624            if is_leading_whitespace && ch.is_whitespace() {
2625                continue;
2626            }
2627
2628            is_leading_whitespace = false;
2629
2630            if ch == '\n' || count >= 40 {
2631                break;
2632            }
2633
2634            if ch.is_whitespace() {
2635                if !prev_was_space {
2636                    title.push(' ');
2637                    count += 1;
2638                    prev_was_space = true;
2639                }
2640            } else {
2641                title.push(ch);
2642                count += 1;
2643                prev_was_space = false;
2644            }
2645        }
2646
2647        let title = title.trim_end().to_string();
2648
2649        if title.is_empty() {
2650            return None;
2651        }
2652
2653        Some(title.into())
2654    }
2655
2656    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2657        self.title = Some(title);
2658        cx.notify();
2659    }
2660
2661    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2662    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2663        for buffer_state in self.buffers.borrow().values() {
2664            buffer_state
2665                .buffer
2666                .update(cx, |buffer, _cx| buffer.refresh_preview());
2667        }
2668    }
2669
2670    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2671    pub fn preserve_preview(&self, cx: &App) -> bool {
2672        self.buffers
2673            .borrow()
2674            .values()
2675            .all(|state| state.buffer.read(cx).preserve_preview())
2676    }
2677
2678    #[cfg(any(test, feature = "test-support"))]
2679    pub fn is_parsing(&self, cx: &App) -> bool {
2680        self.as_singleton().unwrap().read(cx).is_parsing()
2681    }
2682
2683    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2684        let buffer_id = diff.read(cx).buffer_id;
2685        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2686        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2687    }
2688
2689    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2690        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2691    }
2692
2693    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2694        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2695    }
2696
2697    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2698        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2699    }
2700
2701    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2702        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2703        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2704    }
2705
2706    pub fn all_diff_hunks_expanded(&self) -> bool {
2707        self.snapshot.borrow().all_diff_hunks_expanded
2708    }
2709
2710    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2711        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2712        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2713    }
2714
2715    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2716        self.read(cx)
2717            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2718            .nth(1)
2719            .is_some()
2720    }
2721
2722    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2723        let snapshot = self.read(cx);
2724        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2725        let offset_range = range.to_offset(&snapshot);
2726        cursor.seek(&offset_range.start, Bias::Left);
2727        while let Some(item) = cursor.item() {
2728            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2729                break;
2730            }
2731            if item.hunk_info().is_some() {
2732                return true;
2733            }
2734            cursor.next();
2735        }
2736        false
2737    }
2738
2739    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2740        let snapshot = self.read(cx);
2741        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2742        for range in ranges {
2743            let range = range.to_point(&snapshot);
2744            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2745            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2746            let start = start.saturating_sub(1);
2747            let end = snapshot.len().min(end + 1);
2748            cursor.seek(&start, Bias::Right);
2749            while let Some(item) = cursor.item() {
2750                if *cursor.start() >= end {
2751                    break;
2752                }
2753                if item.hunk_info().is_some() {
2754                    return true;
2755                }
2756                cursor.next();
2757            }
2758        }
2759        false
2760    }
2761
2762    pub fn expand_or_collapse_diff_hunks_inner(
2763        &mut self,
2764        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2765        expand: bool,
2766        cx: &mut Context<Self>,
2767    ) {
2768        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2769            return;
2770        }
2771        self.sync(cx);
2772        let mut snapshot = self.snapshot.borrow_mut();
2773        let mut excerpt_edits = Vec::new();
2774        let mut last_hunk_row = None;
2775        for (range, end_excerpt_id) in ranges {
2776            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2777                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2778                    continue;
2779                }
2780                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2781                    continue;
2782                }
2783                let start = Anchor::in_buffer(
2784                    diff_hunk.excerpt_id,
2785                    diff_hunk.buffer_id,
2786                    diff_hunk.buffer_range.start,
2787                );
2788                let end = Anchor::in_buffer(
2789                    diff_hunk.excerpt_id,
2790                    diff_hunk.buffer_id,
2791                    diff_hunk.buffer_range.end,
2792                );
2793                let start = snapshot.excerpt_offset_for_anchor(&start);
2794                let end = snapshot.excerpt_offset_for_anchor(&end);
2795                last_hunk_row = Some(diff_hunk.row_range.start);
2796                excerpt_edits.push(text::Edit {
2797                    old: start..end,
2798                    new: start..end,
2799                });
2800            }
2801        }
2802
2803        self.sync_diff_transforms(
2804            &mut snapshot,
2805            excerpt_edits,
2806            DiffChangeKind::ExpandOrCollapseHunks { expand },
2807        );
2808        cx.emit(Event::DiffHunksToggled);
2809        cx.emit(Event::Edited {
2810            singleton_buffer_edited: false,
2811            edited_buffer: None,
2812        });
2813    }
2814
2815    pub fn expand_or_collapse_diff_hunks(
2816        &mut self,
2817        ranges: Vec<Range<Anchor>>,
2818        expand: bool,
2819        cx: &mut Context<Self>,
2820    ) {
2821        let snapshot = self.snapshot.borrow().clone();
2822        let ranges = ranges.iter().map(move |range| {
2823            let end_excerpt_id = range.end.excerpt_id;
2824            let range = range.to_point(&snapshot);
2825            let mut peek_end = range.end;
2826            if range.end.row < snapshot.max_row().0 {
2827                peek_end = Point::new(range.end.row + 1, 0);
2828            };
2829            (range.start..peek_end, end_excerpt_id)
2830        });
2831        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2832    }
2833
2834    pub fn resize_excerpt(
2835        &mut self,
2836        id: ExcerptId,
2837        range: Range<text::Anchor>,
2838        cx: &mut Context<Self>,
2839    ) {
2840        self.sync(cx);
2841
2842        let mut snapshot = self.snapshot.borrow_mut();
2843        let locator = snapshot.excerpt_locator_for_id(id);
2844        let mut new_excerpts = SumTree::default();
2845        let mut cursor = snapshot
2846            .excerpts
2847            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2848        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2849
2850        let prefix = cursor.slice(&Some(locator), Bias::Left);
2851        new_excerpts.append(prefix, ());
2852
2853        let mut excerpt = cursor.item().unwrap().clone();
2854        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2855
2856        excerpt.range.context.start = range.start;
2857        excerpt.range.context.end = range.end;
2858        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2859
2860        excerpt.text_summary = excerpt
2861            .buffer
2862            .text_summary_for_range(excerpt.range.context.clone());
2863
2864        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2865        let old_start_offset = cursor.start().1;
2866        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2867        let edit = Edit {
2868            old: old_start_offset..old_start_offset + old_text_len,
2869            new: new_start_offset..new_start_offset + new_text_len,
2870        };
2871
2872        if let Some(last_edit) = edits.last_mut() {
2873            if last_edit.old.end == edit.old.start {
2874                last_edit.old.end = edit.old.end;
2875                last_edit.new.end = edit.new.end;
2876            } else {
2877                edits.push(edit);
2878            }
2879        } else {
2880            edits.push(edit);
2881        }
2882
2883        new_excerpts.push(excerpt, ());
2884
2885        cursor.next();
2886
2887        new_excerpts.append(cursor.suffix(), ());
2888
2889        drop(cursor);
2890        snapshot.excerpts = new_excerpts;
2891
2892        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2893        cx.emit(Event::Edited {
2894            singleton_buffer_edited: false,
2895            edited_buffer: None,
2896        });
2897        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2898        cx.notify();
2899    }
2900
2901    pub fn expand_excerpts(
2902        &mut self,
2903        ids: impl IntoIterator<Item = ExcerptId>,
2904        line_count: u32,
2905        direction: ExpandExcerptDirection,
2906        cx: &mut Context<Self>,
2907    ) {
2908        if line_count == 0 {
2909            return;
2910        }
2911        self.sync(cx);
2912        if !self.excerpts_by_path.is_empty() {
2913            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2914            return;
2915        }
2916        let mut snapshot = self.snapshot.borrow_mut();
2917
2918        let ids = ids.into_iter().collect::<Vec<_>>();
2919        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2920        let mut new_excerpts = SumTree::default();
2921        let mut cursor = snapshot
2922            .excerpts
2923            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2924        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2925
2926        for locator in &locators {
2927            let prefix = cursor.slice(&Some(locator), Bias::Left);
2928            new_excerpts.append(prefix, ());
2929
2930            let mut excerpt = cursor.item().unwrap().clone();
2931            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2932
2933            let up_line_count = if direction.should_expand_up() {
2934                line_count
2935            } else {
2936                0
2937            };
2938
2939            let start_row = excerpt
2940                .range
2941                .context
2942                .start
2943                .to_point(&excerpt.buffer)
2944                .row
2945                .saturating_sub(up_line_count);
2946            let start_point = Point::new(start_row, 0);
2947            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2948
2949            let down_line_count = if direction.should_expand_down() {
2950                line_count
2951            } else {
2952                0
2953            };
2954
2955            let mut end_point = excerpt.buffer.clip_point(
2956                excerpt.range.context.end.to_point(&excerpt.buffer)
2957                    + Point::new(down_line_count, 0),
2958                Bias::Left,
2959            );
2960            end_point.column = excerpt.buffer.line_len(end_point.row);
2961            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2962            excerpt.max_buffer_row = end_point.row;
2963
2964            excerpt.text_summary = excerpt
2965                .buffer
2966                .text_summary_for_range(excerpt.range.context.clone());
2967
2968            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2969            let old_start_offset = cursor.start().1;
2970            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2971            let edit = Edit {
2972                old: old_start_offset..old_start_offset + old_text_len,
2973                new: new_start_offset..new_start_offset + new_text_len,
2974            };
2975
2976            if let Some(last_edit) = edits.last_mut() {
2977                if last_edit.old.end == edit.old.start {
2978                    last_edit.old.end = edit.old.end;
2979                    last_edit.new.end = edit.new.end;
2980                } else {
2981                    edits.push(edit);
2982                }
2983            } else {
2984                edits.push(edit);
2985            }
2986
2987            new_excerpts.push(excerpt, ());
2988
2989            cursor.next();
2990        }
2991
2992        new_excerpts.append(cursor.suffix(), ());
2993
2994        drop(cursor);
2995        snapshot.excerpts = new_excerpts;
2996
2997        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2998        cx.emit(Event::Edited {
2999            singleton_buffer_edited: false,
3000            edited_buffer: None,
3001        });
3002        cx.emit(Event::ExcerptsExpanded { ids });
3003        cx.notify();
3004    }
3005
3006    fn sync(&self, cx: &App) {
3007        let changed = self.buffer_changed_since_sync.replace(false);
3008        if !changed {
3009            return;
3010        }
3011
3012        let mut snapshot = self.snapshot.borrow_mut();
3013        let mut excerpts_to_edit = Vec::new();
3014        let mut non_text_state_updated = false;
3015        let mut is_dirty = false;
3016        let mut has_deleted_file = false;
3017        let mut has_conflict = false;
3018        let mut edited = false;
3019        let mut buffers = self.buffers.borrow_mut();
3020        for buffer_state in buffers.values_mut() {
3021            let buffer = buffer_state.buffer.read(cx);
3022            let version = buffer.version();
3023            let non_text_state_update_count = buffer.non_text_state_update_count();
3024
3025            let buffer_edited = version.changed_since(&buffer_state.last_version);
3026            let buffer_non_text_state_updated =
3027                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3028            if buffer_edited || buffer_non_text_state_updated {
3029                buffer_state.last_version = version;
3030                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3031                excerpts_to_edit.extend(
3032                    buffer_state
3033                        .excerpts
3034                        .iter()
3035                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3036                );
3037            }
3038
3039            edited |= buffer_edited;
3040            non_text_state_updated |= buffer_non_text_state_updated;
3041            is_dirty |= buffer.is_dirty();
3042            has_deleted_file |= buffer
3043                .file()
3044                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3045            has_conflict |= buffer.has_conflict();
3046        }
3047        if edited {
3048            snapshot.edit_count += 1;
3049        }
3050        if non_text_state_updated {
3051            snapshot.non_text_state_update_count += 1;
3052        }
3053        snapshot.is_dirty = is_dirty;
3054        snapshot.has_deleted_file = has_deleted_file;
3055        snapshot.has_conflict = has_conflict;
3056
3057        for (id, diff) in self.diffs.iter() {
3058            if snapshot.diffs.get(id).is_none() {
3059                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3060            }
3061        }
3062
3063        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3064
3065        let mut edits = Vec::new();
3066        let mut new_excerpts = SumTree::default();
3067        let mut cursor = snapshot
3068            .excerpts
3069            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3070
3071        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3072            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3073            let old_excerpt = cursor.item().unwrap();
3074            let buffer = buffer.read(cx);
3075            let buffer_id = buffer.remote_id();
3076
3077            let mut new_excerpt;
3078            if buffer_edited {
3079                edits.extend(
3080                    buffer
3081                        .edits_since_in_range::<usize>(
3082                            old_excerpt.buffer.version(),
3083                            old_excerpt.range.context.clone(),
3084                        )
3085                        .map(|edit| {
3086                            let excerpt_old_start = cursor.start().1;
3087                            let excerpt_new_start =
3088                                ExcerptOffset::new(new_excerpts.summary().text.len);
3089                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3090                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3091                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3092                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3093                            Edit {
3094                                old: old_start..old_end,
3095                                new: new_start..new_end,
3096                            }
3097                        }),
3098                );
3099
3100                new_excerpt = Excerpt::new(
3101                    old_excerpt.id,
3102                    locator.clone(),
3103                    buffer_id,
3104                    buffer.snapshot(),
3105                    old_excerpt.range.clone(),
3106                    old_excerpt.has_trailing_newline,
3107                );
3108            } else {
3109                new_excerpt = old_excerpt.clone();
3110                new_excerpt.buffer = buffer.snapshot();
3111            }
3112
3113            new_excerpts.push(new_excerpt, ());
3114            cursor.next();
3115        }
3116        new_excerpts.append(cursor.suffix(), ());
3117
3118        drop(cursor);
3119        snapshot.excerpts = new_excerpts;
3120
3121        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3122    }
3123
3124    fn sync_diff_transforms(
3125        &self,
3126        snapshot: &mut MultiBufferSnapshot,
3127        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3128        change_kind: DiffChangeKind,
3129    ) {
3130        if excerpt_edits.is_empty() {
3131            return;
3132        }
3133
3134        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3135        let mut old_diff_transforms = snapshot
3136            .diff_transforms
3137            .cursor::<Dimensions<ExcerptOffset, usize>>(());
3138        let mut new_diff_transforms = SumTree::default();
3139        let mut old_expanded_hunks = HashSet::default();
3140        let mut output_edits = Vec::new();
3141        let mut output_delta = 0_isize;
3142        let mut at_transform_boundary = true;
3143        let mut end_of_current_insert = None;
3144
3145        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3146        while let Some(edit) = excerpt_edits.next() {
3147            excerpts.seek_forward(&edit.new.start, Bias::Right);
3148            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3149                excerpts.prev();
3150            }
3151
3152            // Keep any transforms that are before the edit.
3153            if at_transform_boundary {
3154                at_transform_boundary = false;
3155                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3156                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3157                if let Some(transform) = old_diff_transforms.item()
3158                    && old_diff_transforms.end().0 == edit.old.start
3159                    && old_diff_transforms.start().0 < edit.old.start
3160                {
3161                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3162                    old_diff_transforms.next();
3163                }
3164            }
3165
3166            // Compute the start of the edit in output coordinates.
3167            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3168            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3169            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3170
3171            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3172                &edit,
3173                &mut excerpts,
3174                &mut old_diff_transforms,
3175                &mut new_diff_transforms,
3176                &mut end_of_current_insert,
3177                &mut old_expanded_hunks,
3178                snapshot,
3179                change_kind,
3180            );
3181
3182            // Compute the end of the edit in output coordinates.
3183            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3184            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3185            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3186            let edit_new_end =
3187                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3188            let output_edit = Edit {
3189                old: edit_old_start..edit_old_end,
3190                new: edit_new_start..edit_new_end,
3191            };
3192
3193            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3194            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3195            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3196                output_edits.push(output_edit);
3197            }
3198
3199            // If this is the last edit that intersects the current diff transform,
3200            // then recreate the content up to the end of this transform, to prepare
3201            // for reusing additional slices of the old transforms.
3202            if excerpt_edits
3203                .peek()
3204                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3205            {
3206                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3207                    && match old_diff_transforms.item() {
3208                        Some(DiffTransform::BufferContent {
3209                            inserted_hunk_info: Some(hunk),
3210                            ..
3211                        }) => excerpts.item().is_some_and(|excerpt| {
3212                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3213                        }),
3214                        _ => true,
3215                    };
3216
3217                let mut excerpt_offset = edit.new.end;
3218                if !keep_next_old_transform {
3219                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3220                    old_diff_transforms.next();
3221                }
3222
3223                old_expanded_hunks.clear();
3224                self.push_buffer_content_transform(
3225                    snapshot,
3226                    &mut new_diff_transforms,
3227                    excerpt_offset,
3228                    end_of_current_insert,
3229                );
3230                at_transform_boundary = true;
3231            }
3232        }
3233
3234        // Keep any transforms that are after the last edit.
3235        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3236
3237        // Ensure there's always at least one buffer content transform.
3238        if new_diff_transforms.is_empty() {
3239            new_diff_transforms.push(
3240                DiffTransform::BufferContent {
3241                    summary: Default::default(),
3242                    inserted_hunk_info: None,
3243                },
3244                (),
3245            );
3246        }
3247
3248        self.subscriptions.publish(output_edits);
3249        drop(old_diff_transforms);
3250        drop(excerpts);
3251        snapshot.diff_transforms = new_diff_transforms;
3252        snapshot.edit_count += 1;
3253
3254        #[cfg(any(test, feature = "test-support"))]
3255        snapshot.check_invariants();
3256    }
3257
3258    fn recompute_diff_transforms_for_edit(
3259        &self,
3260        edit: &Edit<TypedOffset<Excerpt>>,
3261        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3262        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3263        new_diff_transforms: &mut SumTree<DiffTransform>,
3264        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3265        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3266        snapshot: &MultiBufferSnapshot,
3267        change_kind: DiffChangeKind,
3268    ) -> bool {
3269        log::trace!(
3270            "recomputing diff transform for edit {:?} => {:?}",
3271            edit.old.start.value..edit.old.end.value,
3272            edit.new.start.value..edit.new.end.value
3273        );
3274
3275        // Record which hunks were previously expanded.
3276        while let Some(item) = old_diff_transforms.item() {
3277            if let Some(hunk_info) = item.hunk_info() {
3278                log::trace!(
3279                    "previously expanded hunk at {}",
3280                    old_diff_transforms.start().0
3281                );
3282                old_expanded_hunks.insert(hunk_info);
3283            }
3284            if old_diff_transforms.end().0 > edit.old.end {
3285                break;
3286            }
3287            old_diff_transforms.next();
3288        }
3289
3290        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3291        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3292        if old_expanded_hunks.is_empty()
3293            && change_kind == DiffChangeKind::BufferEdited
3294            && !all_diff_hunks_expanded
3295        {
3296            return false;
3297        }
3298
3299        // Visit each excerpt that intersects the edit.
3300        let mut did_expand_hunks = false;
3301        while let Some(excerpt) = excerpts.item() {
3302            // Recompute the expanded hunks in the portion of the excerpt that
3303            // intersects the edit.
3304            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3305                let buffer = &excerpt.buffer;
3306                let excerpt_start = *excerpts.start();
3307                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3308                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3309                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3310                let edit_buffer_start =
3311                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3312                let edit_buffer_end =
3313                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3314                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3315                let edit_anchor_range =
3316                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3317
3318                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3319                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3320                        continue;
3321                    }
3322
3323                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3324                    if hunk_buffer_range.start < excerpt_buffer_start {
3325                        log::trace!("skipping hunk that starts before excerpt");
3326                        continue;
3327                    }
3328
3329                    let hunk_info = DiffTransformHunkInfo {
3330                        excerpt_id: excerpt.id,
3331                        hunk_start_anchor: hunk.buffer_range.start,
3332                        hunk_secondary_status: hunk.secondary_status,
3333                    };
3334
3335                    let hunk_excerpt_start = excerpt_start
3336                        + ExcerptOffset::new(
3337                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3338                        );
3339                    let hunk_excerpt_end = excerpt_end.min(
3340                        excerpt_start
3341                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3342                    );
3343
3344                    self.push_buffer_content_transform(
3345                        snapshot,
3346                        new_diff_transforms,
3347                        hunk_excerpt_start,
3348                        *end_of_current_insert,
3349                    );
3350
3351                    // For every existing hunk, determine if it was previously expanded
3352                    // and if it should currently be expanded.
3353                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3354                    let should_expand_hunk = match &change_kind {
3355                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3356                            was_previously_expanded || all_diff_hunks_expanded
3357                        }
3358                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3359                            let intersects = hunk_buffer_range.is_empty()
3360                                || hunk_buffer_range.end > edit_buffer_start;
3361                            if *expand {
3362                                intersects || was_previously_expanded || all_diff_hunks_expanded
3363                            } else {
3364                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3365                            }
3366                        }
3367                        _ => was_previously_expanded || all_diff_hunks_expanded,
3368                    };
3369
3370                    if should_expand_hunk {
3371                        did_expand_hunks = true;
3372                        log::trace!(
3373                            "expanding hunk {:?}, excerpt:{:?}",
3374                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3375                            excerpt.id
3376                        );
3377
3378                        if !hunk.diff_base_byte_range.is_empty()
3379                            && hunk_buffer_range.start >= edit_buffer_start
3380                            && hunk_buffer_range.start <= excerpt_buffer_end
3381                        {
3382                            let base_text = diff.base_text();
3383                            let mut text_cursor =
3384                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3385                            let mut base_text_summary =
3386                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3387
3388                            let mut has_trailing_newline = false;
3389                            if base_text_summary.last_line_chars > 0 {
3390                                base_text_summary += TextSummary::newline();
3391                                has_trailing_newline = true;
3392                            }
3393
3394                            new_diff_transforms.push(
3395                                DiffTransform::DeletedHunk {
3396                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3397                                    summary: base_text_summary,
3398                                    buffer_id: excerpt.buffer_id,
3399                                    hunk_info,
3400                                    has_trailing_newline,
3401                                },
3402                                (),
3403                            );
3404                        }
3405
3406                        if !hunk_buffer_range.is_empty() {
3407                            *end_of_current_insert =
3408                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3409                        }
3410                    }
3411                }
3412            }
3413
3414            if excerpts.end() <= edit.new.end {
3415                excerpts.next();
3416            } else {
3417                break;
3418            }
3419        }
3420
3421        did_expand_hunks || !old_expanded_hunks.is_empty()
3422    }
3423
3424    fn append_diff_transforms(
3425        &self,
3426        new_transforms: &mut SumTree<DiffTransform>,
3427        subtree: SumTree<DiffTransform>,
3428    ) {
3429        if let Some(DiffTransform::BufferContent {
3430            inserted_hunk_info,
3431            summary,
3432        }) = subtree.first()
3433            && self.extend_last_buffer_content_transform(
3434                new_transforms,
3435                *inserted_hunk_info,
3436                *summary,
3437            )
3438        {
3439            let mut cursor = subtree.cursor::<()>(());
3440            cursor.next();
3441            cursor.next();
3442            new_transforms.append(cursor.suffix(), ());
3443            return;
3444        }
3445        new_transforms.append(subtree, ());
3446    }
3447
3448    fn push_diff_transform(
3449        &self,
3450        new_transforms: &mut SumTree<DiffTransform>,
3451        transform: DiffTransform,
3452    ) {
3453        if let DiffTransform::BufferContent {
3454            inserted_hunk_info: inserted_hunk_anchor,
3455            summary,
3456        } = transform
3457            && self.extend_last_buffer_content_transform(
3458                new_transforms,
3459                inserted_hunk_anchor,
3460                summary,
3461            )
3462        {
3463            return;
3464        }
3465        new_transforms.push(transform, ());
3466    }
3467
3468    fn push_buffer_content_transform(
3469        &self,
3470        old_snapshot: &MultiBufferSnapshot,
3471        new_transforms: &mut SumTree<DiffTransform>,
3472        end_offset: ExcerptOffset,
3473        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3474    ) {
3475        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3476            (end_offset.min(insertion_end_offset), Some(hunk_info))
3477        });
3478        let unchanged_region = [(end_offset, None)];
3479
3480        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3481        {
3482            let start_offset = new_transforms.summary().excerpt_len();
3483            if end_offset <= start_offset {
3484                continue;
3485            }
3486            let summary_to_add = old_snapshot
3487                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3488
3489            if !self.extend_last_buffer_content_transform(
3490                new_transforms,
3491                inserted_hunk_info,
3492                summary_to_add,
3493            ) {
3494                new_transforms.push(
3495                    DiffTransform::BufferContent {
3496                        summary: summary_to_add,
3497                        inserted_hunk_info,
3498                    },
3499                    (),
3500                )
3501            }
3502        }
3503    }
3504
3505    fn extend_last_buffer_content_transform(
3506        &self,
3507        new_transforms: &mut SumTree<DiffTransform>,
3508        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3509        summary_to_add: TextSummary,
3510    ) -> bool {
3511        let mut did_extend = false;
3512        new_transforms.update_last(
3513            |last_transform| {
3514                if let DiffTransform::BufferContent {
3515                    summary,
3516                    inserted_hunk_info: inserted_hunk_anchor,
3517                } = last_transform
3518                    && *inserted_hunk_anchor == new_inserted_hunk_info
3519                {
3520                    *summary += summary_to_add;
3521                    did_extend = true;
3522                }
3523            },
3524            (),
3525        );
3526        did_extend
3527    }
3528}
3529
3530fn build_excerpt_ranges(
3531    ranges: impl IntoIterator<Item = Range<Point>>,
3532    context_line_count: u32,
3533    buffer_snapshot: &BufferSnapshot,
3534) -> Vec<ExcerptRange<Point>> {
3535    ranges
3536        .into_iter()
3537        .map(|range| {
3538            let start_row = range.start.row.saturating_sub(context_line_count);
3539            let start = Point::new(start_row, 0);
3540            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3541            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3542            ExcerptRange {
3543                context: start..end,
3544                primary: range,
3545            }
3546        })
3547        .collect()
3548}
3549
3550#[cfg(any(test, feature = "test-support"))]
3551impl MultiBuffer {
3552    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3553        let buffer = cx.new(|cx| Buffer::local(text, cx));
3554        cx.new(|cx| Self::singleton(buffer, cx))
3555    }
3556
3557    pub fn build_multi<const COUNT: usize>(
3558        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3559        cx: &mut gpui::App,
3560    ) -> Entity<Self> {
3561        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3562        for (text, ranges) in excerpts {
3563            let buffer = cx.new(|cx| Buffer::local(text, cx));
3564            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3565            multi.update(cx, |multi, cx| {
3566                multi.push_excerpts(buffer, excerpt_ranges, cx)
3567            });
3568        }
3569
3570        multi
3571    }
3572
3573    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3574        cx.new(|cx| Self::singleton(buffer, cx))
3575    }
3576
3577    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3578        cx.new(|cx| {
3579            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3580            let mutation_count = rng.random_range(1..=5);
3581            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3582            multibuffer
3583        })
3584    }
3585
3586    pub fn randomly_edit(
3587        &mut self,
3588        rng: &mut impl rand::Rng,
3589        edit_count: usize,
3590        cx: &mut Context<Self>,
3591    ) {
3592        use util::RandomCharIter;
3593
3594        let snapshot = self.read(cx);
3595        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3596        let mut last_end = None;
3597        for _ in 0..edit_count {
3598            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3599                break;
3600            }
3601
3602            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3603            let end =
3604                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3605            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3606            last_end = Some(end);
3607
3608            let mut range = start..end;
3609            if rng.random_bool(0.2) {
3610                mem::swap(&mut range.start, &mut range.end);
3611            }
3612
3613            let new_text_len = rng.random_range(0..10);
3614            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3615
3616            edits.push((range, new_text.into()));
3617        }
3618        log::info!("mutating multi-buffer with {:?}", edits);
3619        drop(snapshot);
3620
3621        self.edit(edits, None, cx);
3622    }
3623
3624    pub fn randomly_edit_excerpts(
3625        &mut self,
3626        rng: &mut impl rand::Rng,
3627        mutation_count: usize,
3628        cx: &mut Context<Self>,
3629    ) {
3630        use rand::prelude::*;
3631        use std::env;
3632        use util::RandomCharIter;
3633
3634        let max_excerpts = env::var("MAX_EXCERPTS")
3635            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3636            .unwrap_or(5);
3637
3638        let mut buffers = Vec::new();
3639        for _ in 0..mutation_count {
3640            if rng.random_bool(0.05) {
3641                log::info!("Clearing multi-buffer");
3642                self.clear(cx);
3643                continue;
3644            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3645                let ids = self.excerpt_ids();
3646                let mut excerpts = HashSet::default();
3647                for _ in 0..rng.random_range(0..ids.len()) {
3648                    excerpts.extend(ids.choose(rng).copied());
3649                }
3650
3651                let line_count = rng.random_range(0..5);
3652
3653                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3654
3655                self.expand_excerpts(
3656                    excerpts.iter().cloned(),
3657                    line_count,
3658                    ExpandExcerptDirection::UpAndDown,
3659                    cx,
3660                );
3661                continue;
3662            }
3663
3664            let excerpt_ids = self.excerpt_ids();
3665            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3666                let buffer_handle = if rng.random() || self.buffers.borrow().is_empty() {
3667                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3668                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3669                    let buffer = buffers.last().unwrap().read(cx);
3670                    log::info!(
3671                        "Creating new buffer {} with text: {:?}",
3672                        buffer.remote_id(),
3673                        buffer.text()
3674                    );
3675                    buffers.last().unwrap().clone()
3676                } else {
3677                    self.buffers
3678                        .borrow()
3679                        .values()
3680                        .choose(rng)
3681                        .unwrap()
3682                        .buffer
3683                        .clone()
3684                };
3685
3686                let buffer = buffer_handle.read(cx);
3687                let buffer_text = buffer.text();
3688                let ranges = (0..rng.random_range(0..5))
3689                    .map(|_| {
3690                        let end_ix =
3691                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3692                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3693                        ExcerptRange::new(start_ix..end_ix)
3694                    })
3695                    .collect::<Vec<_>>();
3696                log::info!(
3697                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3698                    buffer_handle.read(cx).remote_id(),
3699                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3700                    ranges
3701                        .iter()
3702                        .map(|r| &buffer_text[r.context.clone()])
3703                        .collect::<Vec<_>>()
3704                );
3705
3706                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3707                log::info!("Inserted with ids: {:?}", excerpt_id);
3708            } else {
3709                let remove_count = rng.random_range(1..=excerpt_ids.len());
3710                let mut excerpts_to_remove = excerpt_ids
3711                    .choose_multiple(rng, remove_count)
3712                    .cloned()
3713                    .collect::<Vec<_>>();
3714                let snapshot = self.snapshot.borrow();
3715                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3716                drop(snapshot);
3717                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3718                self.remove_excerpts(excerpts_to_remove, cx);
3719            }
3720        }
3721    }
3722
3723    pub fn randomly_mutate(
3724        &mut self,
3725        rng: &mut impl rand::Rng,
3726        mutation_count: usize,
3727        cx: &mut Context<Self>,
3728    ) {
3729        use rand::prelude::*;
3730
3731        if rng.random_bool(0.7) || self.singleton {
3732            let buffer = self
3733                .buffers
3734                .borrow()
3735                .values()
3736                .choose(rng)
3737                .map(|state| state.buffer.clone());
3738
3739            if let Some(buffer) = buffer {
3740                buffer.update(cx, |buffer, cx| {
3741                    if rng.random() {
3742                        buffer.randomly_edit(rng, mutation_count, cx);
3743                    } else {
3744                        buffer.randomly_undo_redo(rng, cx);
3745                    }
3746                });
3747            } else {
3748                self.randomly_edit(rng, mutation_count, cx);
3749            }
3750        } else {
3751            self.randomly_edit_excerpts(rng, mutation_count, cx);
3752        }
3753
3754        self.check_invariants(cx);
3755    }
3756
3757    fn check_invariants(&self, cx: &App) {
3758        self.read(cx).check_invariants();
3759    }
3760}
3761
3762impl EventEmitter<Event> for MultiBuffer {}
3763
3764impl MultiBufferSnapshot {
3765    pub fn text(&self) -> String {
3766        self.chunks(0..self.len(), false)
3767            .map(|chunk| chunk.text)
3768            .collect()
3769    }
3770
3771    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3772        self.reversed_chunks_in_range(0..position.to_offset(self))
3773            .flat_map(|c| c.chars().rev())
3774    }
3775
3776    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3777        let mut cursor = self.cursor::<usize>();
3778        cursor.seek(&range.end);
3779        let current_chunks = cursor.region().as_ref().map(|region| {
3780            let start_overshoot = range.start.saturating_sub(region.range.start);
3781            let end_overshoot = range.end - region.range.start;
3782            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3783            let start = region.buffer_range.start + start_overshoot;
3784            region.buffer.reversed_chunks_in_range(start..end)
3785        });
3786        ReversedMultiBufferChunks {
3787            cursor,
3788            current_chunks,
3789            start: range.start,
3790            offset: range.end,
3791        }
3792    }
3793
3794    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3795        let offset = position.to_offset(self);
3796        self.text_for_range(offset..self.len())
3797            .flat_map(|chunk| chunk.chars())
3798    }
3799
3800    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3801        self.chunks(range, false).map(|chunk| chunk.text)
3802    }
3803
3804    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3805        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3806            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3807    }
3808
3809    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3810    where
3811        T: ToOffset,
3812    {
3813        let position = position.to_offset(self);
3814        position == self.clip_offset(position, Bias::Left)
3815            && self
3816                .bytes_in_range(position..self.len())
3817                .flatten()
3818                .copied()
3819                .take(needle.len())
3820                .eq(needle.bytes())
3821    }
3822
3823    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3824        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3825    }
3826
3827    pub fn diff_hunks_in_range<T: ToPoint>(
3828        &self,
3829        range: Range<T>,
3830    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3831        let query_range = range.start.to_point(self)..range.end.to_point(self);
3832        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3833            let diff = self.diffs.get(&buffer.remote_id())?;
3834            let buffer_start = buffer.anchor_before(buffer_range.start);
3835            let buffer_end = buffer.anchor_after(buffer_range.end);
3836            Some(
3837                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3838                    .filter_map(|hunk| {
3839                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3840                            return None;
3841                        }
3842                        Some((hunk.range.clone(), hunk))
3843                    }),
3844            )
3845        })
3846        .filter_map(move |(range, hunk, excerpt)| {
3847            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3848            {
3849                return None;
3850            }
3851            let end_row = if range.end.column == 0 {
3852                range.end.row
3853            } else {
3854                range.end.row + 1
3855            };
3856            Some(MultiBufferDiffHunk {
3857                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3858                buffer_id: excerpt.buffer_id,
3859                excerpt_id: excerpt.id,
3860                buffer_range: hunk.buffer_range.clone(),
3861                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3862                secondary_status: hunk.secondary_status,
3863            })
3864        })
3865    }
3866
3867    pub fn excerpt_ids_for_range<T: ToOffset>(
3868        &self,
3869        range: Range<T>,
3870    ) -> impl Iterator<Item = ExcerptId> + '_ {
3871        let range = range.start.to_offset(self)..range.end.to_offset(self);
3872        let mut cursor = self.cursor::<usize>();
3873        cursor.seek(&range.start);
3874        std::iter::from_fn(move || {
3875            let region = cursor.region()?;
3876            if region.range.start >= range.end {
3877                return None;
3878            }
3879            cursor.next_excerpt();
3880            Some(region.excerpt.id)
3881        })
3882    }
3883
3884    pub fn buffer_ids_for_range<T: ToOffset>(
3885        &self,
3886        range: Range<T>,
3887    ) -> impl Iterator<Item = BufferId> + '_ {
3888        let range = range.start.to_offset(self)..range.end.to_offset(self);
3889        let mut cursor = self.cursor::<usize>();
3890        cursor.seek(&range.start);
3891        std::iter::from_fn(move || {
3892            let region = cursor.region()?;
3893            if region.range.start > range.end
3894                || region.range.start == range.end && region.range.start > range.start
3895            {
3896                return None;
3897            }
3898            cursor.next_excerpt();
3899            Some(region.excerpt.buffer_id)
3900        })
3901    }
3902
3903    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3904        &self,
3905        ranges: impl Iterator<Item = Range<T>>,
3906    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3907        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3908    }
3909
3910    pub fn range_to_buffer_ranges<T: ToOffset>(
3911        &self,
3912        range: Range<T>,
3913    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3914        let start = range.start.to_offset(self);
3915        let end = range.end.to_offset(self);
3916
3917        let mut cursor = self.cursor::<usize>();
3918        cursor.seek(&start);
3919
3920        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3921        while let Some(region) = cursor.region() {
3922            if region.range.start > end {
3923                break;
3924            }
3925            if region.is_main_buffer {
3926                let start_overshoot = start.saturating_sub(region.range.start);
3927                let end_overshoot = end.saturating_sub(region.range.start);
3928                let start = region
3929                    .buffer_range
3930                    .end
3931                    .min(region.buffer_range.start + start_overshoot);
3932                let end = region
3933                    .buffer_range
3934                    .end
3935                    .min(region.buffer_range.start + end_overshoot);
3936                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3937                    *excerpt_id == region.excerpt.id && prev_range.end == start
3938                }) {
3939                    prev.1.end = end;
3940                } else {
3941                    result.push((region.buffer, start..end, region.excerpt.id));
3942                }
3943            }
3944            cursor.next();
3945        }
3946        result
3947    }
3948
3949    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3950        &self,
3951        range: Range<T>,
3952    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3953        let start = range.start.to_offset(self);
3954        let end = range.end.to_offset(self);
3955
3956        let mut cursor = self.cursor::<usize>();
3957        cursor.seek(&start);
3958
3959        std::iter::from_fn(move || {
3960            let region = cursor.region()?;
3961            if region.range.start > end {
3962                return None;
3963            }
3964            let start_overshoot = start.saturating_sub(region.range.start);
3965            let end_overshoot = end.saturating_sub(region.range.start);
3966            let start = region
3967                .buffer_range
3968                .end
3969                .min(region.buffer_range.start + start_overshoot);
3970            let end = region
3971                .buffer_range
3972                .end
3973                .min(region.buffer_range.start + end_overshoot);
3974
3975            let region_excerpt_id = region.excerpt.id;
3976            let deleted_hunk_anchor = if region.is_main_buffer {
3977                None
3978            } else {
3979                Some(self.anchor_before(region.range.start))
3980            };
3981            let result = (
3982                region.buffer,
3983                start..end,
3984                region_excerpt_id,
3985                deleted_hunk_anchor,
3986            );
3987            cursor.next();
3988            Some(result)
3989        })
3990    }
3991
3992    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3993    /// coordinates.
3994    ///
3995    /// The given callback will be called for every excerpt intersecting the given range. It will
3996    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3997    /// The callback should return an iterator of metadata items from that buffer, each paired
3998    /// with a buffer range.
3999    ///
4000    /// The returned iterator yields each of these metadata items, paired with its range in
4001    /// multi-buffer coordinates.
4002    fn lift_buffer_metadata<'a, D, M, I>(
4003        &'a self,
4004        query_range: Range<D>,
4005        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
4006    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
4007    where
4008        I: Iterator<Item = (Range<D>, M)> + 'a,
4009        D: TextDimension + Ord + Sub<D, Output = D>,
4010    {
4011        let max_position = D::from_text_summary(&self.text_summary());
4012        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4013        let mut cursor = self.cursor::<D>();
4014
4015        // Find the excerpt and buffer offset where the given range ends.
4016        cursor.seek(&query_range.end);
4017        let mut range_end = None;
4018        while let Some(region) = cursor.region() {
4019            if region.is_main_buffer {
4020                let mut buffer_end = region.buffer_range.start;
4021                let overshoot = if query_range.end > region.range.start {
4022                    query_range.end - region.range.start
4023                } else {
4024                    D::default()
4025                };
4026                buffer_end.add_assign(&overshoot);
4027                range_end = Some((region.excerpt.id, buffer_end));
4028                break;
4029            }
4030            cursor.next();
4031        }
4032
4033        cursor.seek(&query_range.start);
4034
4035        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4036            && region.range.start > D::zero(())
4037        {
4038            cursor.prev()
4039        }
4040
4041        iter::from_fn(move || {
4042            loop {
4043                let excerpt = cursor.excerpt()?;
4044
4045                // If we have already retrieved metadata for this excerpt, continue to use it.
4046                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4047                    .as_mut()
4048                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4049                {
4050                    Some(metadata)
4051                }
4052                // Otherwise, compute the intersection of the input range with the excerpt's range,
4053                // and retrieve the metadata for the resulting range.
4054                else {
4055                    let region = cursor.region()?;
4056                    let mut buffer_start;
4057                    if region.is_main_buffer {
4058                        buffer_start = region.buffer_range.start;
4059                        if query_range.start > region.range.start {
4060                            let overshoot = query_range.start - region.range.start;
4061                            buffer_start.add_assign(&overshoot);
4062                        }
4063                        buffer_start = buffer_start.min(region.buffer_range.end);
4064                    } else {
4065                        buffer_start = cursor.main_buffer_position()?;
4066                    };
4067                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4068                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4069                        && excerpt.id == end_excerpt_id
4070                    {
4071                        buffer_end = buffer_end.min(end_buffer_offset);
4072                    }
4073
4074                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4075                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4076                    })
4077                };
4078
4079                // Visit each metadata item.
4080                if let Some((metadata_buffer_range, metadata)) =
4081                    metadata_iter.and_then(Iterator::next)
4082                {
4083                    // Find the multibuffer regions that contain the start and end of
4084                    // the metadata item's range.
4085                    if metadata_buffer_range.start > D::default() {
4086                        while let Some(region) = cursor.region() {
4087                            if region.is_main_buffer
4088                                && (region.buffer_range.end >= metadata_buffer_range.start
4089                                    || cursor.is_at_end_of_excerpt())
4090                            {
4091                                break;
4092                            }
4093                            cursor.next();
4094                        }
4095                    }
4096                    let start_region = cursor.region()?;
4097                    while let Some(region) = cursor.region() {
4098                        if region.is_main_buffer
4099                            && (region.buffer_range.end > metadata_buffer_range.end
4100                                || cursor.is_at_end_of_excerpt())
4101                        {
4102                            break;
4103                        }
4104                        cursor.next();
4105                    }
4106                    let end_region = cursor.region();
4107
4108                    // Convert the metadata item's range into multibuffer coordinates.
4109                    let mut start_position = start_region.range.start;
4110                    let region_buffer_start = start_region.buffer_range.start;
4111                    if start_region.is_main_buffer
4112                        && metadata_buffer_range.start > region_buffer_start
4113                    {
4114                        start_position
4115                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4116                        start_position = start_position.min(start_region.range.end);
4117                    }
4118
4119                    let mut end_position = max_position;
4120                    if let Some(end_region) = &end_region {
4121                        end_position = end_region.range.start;
4122                        debug_assert!(end_region.is_main_buffer);
4123                        let region_buffer_start = end_region.buffer_range.start;
4124                        if metadata_buffer_range.end > region_buffer_start {
4125                            end_position
4126                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4127                        }
4128                        end_position = end_position.min(end_region.range.end);
4129                    }
4130
4131                    if start_position <= query_range.end && end_position >= query_range.start {
4132                        return Some((start_position..end_position, metadata, excerpt));
4133                    }
4134                }
4135                // When there are no more metadata items for this excerpt, move to the next excerpt.
4136                else {
4137                    current_excerpt_metadata.take();
4138                    if let Some((end_excerpt_id, _)) = range_end
4139                        && excerpt.id == end_excerpt_id
4140                    {
4141                        return None;
4142                    }
4143                    cursor.next_excerpt();
4144                }
4145            }
4146        })
4147    }
4148
4149    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4150        let offset = position.to_offset(self);
4151
4152        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4153        cursor.seek(&DimensionPair {
4154            key: offset,
4155            value: None,
4156        });
4157        cursor.seek_to_start_of_current_excerpt();
4158        let excerpt = cursor.excerpt()?;
4159
4160        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4161        let current_position = self
4162            .anchor_before(offset)
4163            .text_anchor
4164            .to_offset(&excerpt.buffer);
4165        let excerpt_end = excerpt
4166            .buffer
4167            .anchor_before(excerpt_end.min(current_position));
4168
4169        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4170            for hunk in diff.hunks_intersecting_range_rev(
4171                excerpt.range.context.start..excerpt_end,
4172                &excerpt.buffer,
4173            ) {
4174                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4175                if hunk_end >= current_position {
4176                    continue;
4177                }
4178                let start =
4179                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4180                        .to_point(self);
4181                return Some(MultiBufferRow(start.row));
4182            }
4183        }
4184
4185        loop {
4186            cursor.prev_excerpt();
4187            let excerpt = cursor.excerpt()?;
4188
4189            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4190                continue;
4191            };
4192            let mut hunks =
4193                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4194            let Some(hunk) = hunks.next() else {
4195                continue;
4196            };
4197            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4198                .to_point(self);
4199            return Some(MultiBufferRow(start.row));
4200        }
4201    }
4202
4203    pub fn has_diff_hunks(&self) -> bool {
4204        self.diffs.values().any(|diff| !diff.is_empty())
4205    }
4206
4207    pub fn is_inside_word<T: ToOffset>(
4208        &self,
4209        position: T,
4210        scope_context: Option<CharScopeContext>,
4211    ) -> bool {
4212        let position = position.to_offset(self);
4213        let classifier = self
4214            .char_classifier_at(position)
4215            .scope_context(scope_context);
4216        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4217        let prev_char_kind = self
4218            .reversed_chars_at(position)
4219            .next()
4220            .map(|c| classifier.kind(c));
4221        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4222    }
4223
4224    pub fn surrounding_word<T: ToOffset>(
4225        &self,
4226        start: T,
4227        scope_context: Option<CharScopeContext>,
4228    ) -> (Range<usize>, Option<CharKind>) {
4229        let mut start = start.to_offset(self);
4230        let mut end = start;
4231        let mut next_chars = self.chars_at(start).peekable();
4232        let mut prev_chars = self.reversed_chars_at(start).peekable();
4233
4234        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4235
4236        let word_kind = cmp::max(
4237            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4238            next_chars.peek().copied().map(|c| classifier.kind(c)),
4239        );
4240
4241        for ch in prev_chars {
4242            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4243                start -= ch.len_utf8();
4244            } else {
4245                break;
4246            }
4247        }
4248
4249        for ch in next_chars {
4250            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4251                end += ch.len_utf8();
4252            } else {
4253                break;
4254            }
4255        }
4256
4257        (start..end, word_kind)
4258    }
4259
4260    pub fn char_kind_before<T: ToOffset>(
4261        &self,
4262        start: T,
4263        scope_context: Option<CharScopeContext>,
4264    ) -> Option<CharKind> {
4265        let start = start.to_offset(self);
4266        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4267        self.reversed_chars_at(start)
4268            .next()
4269            .map(|ch| classifier.kind(ch))
4270    }
4271
4272    pub fn is_singleton(&self) -> bool {
4273        self.singleton
4274    }
4275
4276    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4277        if self.singleton {
4278            self.excerpts
4279                .iter()
4280                .next()
4281                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4282        } else {
4283            None
4284        }
4285    }
4286
4287    pub fn len(&self) -> usize {
4288        self.diff_transforms.summary().output.len
4289    }
4290
4291    pub fn is_empty(&self) -> bool {
4292        self.excerpts.summary().text.len == 0
4293    }
4294
4295    pub fn widest_line_number(&self) -> u32 {
4296        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4297        self.excerpts.summary().widest_line_number + 1
4298    }
4299
4300    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4301        let range = range.start.to_offset(self)..range.end.to_offset(self);
4302        let mut excerpts = self.cursor::<usize>();
4303        excerpts.seek(&range.start);
4304
4305        let mut chunk;
4306        let mut has_trailing_newline;
4307        let excerpt_bytes;
4308        if let Some(region) = excerpts.region() {
4309            let mut bytes = region.buffer.bytes_in_range(
4310                region.buffer_range.start + range.start - region.range.start
4311                    ..(region.buffer_range.start + range.end - region.range.start)
4312                        .min(region.buffer_range.end),
4313            );
4314            chunk = bytes.next().unwrap_or(&[][..]);
4315            excerpt_bytes = Some(bytes);
4316            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4317            if chunk.is_empty() && has_trailing_newline {
4318                chunk = b"\n";
4319                has_trailing_newline = false;
4320            }
4321        } else {
4322            chunk = &[][..];
4323            excerpt_bytes = None;
4324            has_trailing_newline = false;
4325        };
4326
4327        MultiBufferBytes {
4328            range,
4329            cursor: excerpts,
4330            excerpt_bytes,
4331            has_trailing_newline,
4332            chunk,
4333        }
4334    }
4335
4336    pub fn reversed_bytes_in_range<T: ToOffset>(
4337        &self,
4338        range: Range<T>,
4339    ) -> ReversedMultiBufferBytes<'_> {
4340        let range = range.start.to_offset(self)..range.end.to_offset(self);
4341        let mut chunks = self.reversed_chunks_in_range(range.clone());
4342        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4343        ReversedMultiBufferBytes {
4344            range,
4345            chunks,
4346            chunk,
4347        }
4348    }
4349
4350    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4351        let mut cursor = self.cursor::<Point>();
4352        cursor.seek(&Point::new(start_row.0, 0));
4353        let mut result = MultiBufferRows {
4354            point: Point::new(0, 0),
4355            is_empty: self.excerpts.is_empty(),
4356            is_singleton: self.is_singleton(),
4357            cursor,
4358        };
4359        result.seek(start_row);
4360        result
4361    }
4362
4363    pub fn chunks<T: ToOffset>(
4364        &self,
4365        range: Range<T>,
4366        language_aware: bool,
4367    ) -> MultiBufferChunks<'_> {
4368        let mut chunks = MultiBufferChunks {
4369            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4370            range: 0..0,
4371            excerpts: self.excerpts.cursor(()),
4372            diff_transforms: self.diff_transforms.cursor(()),
4373            diffs: &self.diffs,
4374            diff_base_chunks: None,
4375            excerpt_chunks: None,
4376            buffer_chunk: None,
4377            language_aware,
4378        };
4379        let range = range.start.to_offset(self)..range.end.to_offset(self);
4380        chunks.seek(range);
4381        chunks
4382    }
4383
4384    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4385        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4386    }
4387
4388    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4389        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4390    }
4391
4392    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4393        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4394    }
4395
4396    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4397        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4398            buffer.clip_point_utf16(Unclipped(point), bias)
4399        })
4400    }
4401
4402    pub fn offset_to_point(&self, offset: usize) -> Point {
4403        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4404    }
4405
4406    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4407        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4408    }
4409
4410    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4411        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4412    }
4413
4414    pub fn point_to_offset(&self, point: Point) -> usize {
4415        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4416    }
4417
4418    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4419        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4420    }
4421
4422    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4423        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4424    }
4425
4426    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4427        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4428    }
4429
4430    fn clip_dimension<D>(
4431        &self,
4432        position: D,
4433        bias: Bias,
4434        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4435    ) -> D
4436    where
4437        D: TextDimension + Ord + Sub<D, Output = D>,
4438    {
4439        let mut cursor = self.cursor();
4440        cursor.seek(&position);
4441        if let Some(region) = cursor.region() {
4442            if position >= region.range.end {
4443                return region.range.end;
4444            }
4445            let overshoot = position - region.range.start;
4446            let mut buffer_position = region.buffer_range.start;
4447            buffer_position.add_assign(&overshoot);
4448            let clipped_buffer_position =
4449                clip_buffer_position(region.buffer, buffer_position, bias);
4450            let mut position = region.range.start;
4451            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4452            position
4453        } else {
4454            D::from_text_summary(&self.text_summary())
4455        }
4456    }
4457
4458    fn convert_dimension<D1, D2>(
4459        &self,
4460        key: D1,
4461        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4462    ) -> D2
4463    where
4464        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4465        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4466    {
4467        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4468        cursor.seek(&DimensionPair { key, value: None });
4469        if let Some(region) = cursor.region() {
4470            if key >= region.range.end.key {
4471                return region.range.end.value.unwrap();
4472            }
4473            let start_key = region.range.start.key;
4474            let start_value = region.range.start.value.unwrap();
4475            let buffer_start_key = region.buffer_range.start.key;
4476            let buffer_start_value = region.buffer_range.start.value.unwrap();
4477            let mut buffer_key = buffer_start_key;
4478            buffer_key.add_assign(&(key - start_key));
4479            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4480            let mut result = start_value;
4481            result.add_assign(&(buffer_value - buffer_start_value));
4482            result
4483        } else {
4484            D2::from_text_summary(&self.text_summary())
4485        }
4486    }
4487
4488    pub fn point_to_buffer_offset<T: ToOffset>(
4489        &self,
4490        point: T,
4491    ) -> Option<(&BufferSnapshot, usize)> {
4492        let offset = point.to_offset(self);
4493        let mut cursor = self.cursor::<usize>();
4494        cursor.seek(&offset);
4495        let region = cursor.region()?;
4496        let overshoot = offset - region.range.start;
4497        let buffer_offset = region.buffer_range.start + overshoot;
4498        if buffer_offset == region.buffer.len() + 1
4499            && region.has_trailing_newline
4500            && !region.is_main_buffer
4501        {
4502            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4503        } else if buffer_offset > region.buffer.len() {
4504            return None;
4505        }
4506        Some((region.buffer, buffer_offset))
4507    }
4508
4509    pub fn point_to_buffer_point(
4510        &self,
4511        point: Point,
4512    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4513        let mut cursor = self.cursor::<Point>();
4514        cursor.seek(&point);
4515        let region = cursor.region()?;
4516        let overshoot = point - region.range.start;
4517        let buffer_point = region.buffer_range.start + overshoot;
4518        let excerpt = cursor.excerpt()?;
4519        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4520            && region.has_trailing_newline
4521            && !region.is_main_buffer
4522        {
4523            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4524        } else if buffer_point > region.buffer.max_point() {
4525            return None;
4526        }
4527        Some((region.buffer, buffer_point, excerpt.id))
4528    }
4529
4530    pub fn suggested_indents(
4531        &self,
4532        rows: impl IntoIterator<Item = u32>,
4533        cx: &App,
4534    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4535        let mut result = BTreeMap::new();
4536
4537        let mut rows_for_excerpt = Vec::new();
4538        let mut cursor = self.cursor::<Point>();
4539        let mut rows = rows.into_iter().peekable();
4540        let mut prev_row = u32::MAX;
4541        let mut prev_language_indent_size = IndentSize::default();
4542
4543        while let Some(row) = rows.next() {
4544            cursor.seek(&Point::new(row, 0));
4545            let Some(region) = cursor.region() else {
4546                continue;
4547            };
4548
4549            // Retrieve the language and indent size once for each disjoint region being indented.
4550            let single_indent_size = if row.saturating_sub(1) == prev_row {
4551                prev_language_indent_size
4552            } else {
4553                region
4554                    .buffer
4555                    .language_indent_size_at(Point::new(row, 0), cx)
4556            };
4557            prev_language_indent_size = single_indent_size;
4558            prev_row = row;
4559
4560            let start_buffer_row = region.buffer_range.start.row;
4561            let start_multibuffer_row = region.range.start.row;
4562            let end_multibuffer_row = region.range.end.row;
4563
4564            rows_for_excerpt.push(row);
4565            while let Some(next_row) = rows.peek().copied() {
4566                if end_multibuffer_row > next_row {
4567                    rows_for_excerpt.push(next_row);
4568                    rows.next();
4569                } else {
4570                    break;
4571                }
4572            }
4573
4574            let buffer_rows = rows_for_excerpt
4575                .drain(..)
4576                .map(|row| start_buffer_row + row - start_multibuffer_row);
4577            let buffer_indents = region
4578                .buffer
4579                .suggested_indents(buffer_rows, single_indent_size);
4580            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4581                (
4582                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4583                    indent,
4584                )
4585            });
4586            result.extend(multibuffer_indents);
4587        }
4588
4589        result
4590    }
4591
4592    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4593        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4594            let mut size = buffer.indent_size_for_line(range.start.row);
4595            size.len = size
4596                .len
4597                .min(range.end.column)
4598                .saturating_sub(range.start.column);
4599            size
4600        } else {
4601            IndentSize::spaces(0)
4602        }
4603    }
4604
4605    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4606        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4607            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4608        } else {
4609            LineIndent::spaces(0)
4610        }
4611    }
4612
4613    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4614        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4615
4616        if self.language_settings(cx).extend_comment_on_newline
4617            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4618        {
4619            let delimiters = language_scope.line_comment_prefixes();
4620            for delimiter in delimiters {
4621                if *self
4622                    .chars_at(Point::new(row.0, indent.len() as u32))
4623                    .take(delimiter.chars().count())
4624                    .collect::<String>()
4625                    .as_str()
4626                    == **delimiter
4627                {
4628                    indent.push_str(delimiter);
4629                    break;
4630                }
4631            }
4632        }
4633
4634        indent
4635    }
4636
4637    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4638    where
4639        T: ToOffset,
4640    {
4641        for char in self.reversed_chars_at(position) {
4642            if !char.is_whitespace() {
4643                return false;
4644            }
4645            if char == '\n' {
4646                return true;
4647            }
4648        }
4649        true
4650    }
4651
4652    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4653        while row.0 > 0 {
4654            row.0 -= 1;
4655            if !self.is_line_blank(row) {
4656                return Some(row);
4657            }
4658        }
4659        None
4660    }
4661
4662    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4663        if let Some((_, range)) = self.buffer_line_for_row(row) {
4664            range.end.column - range.start.column
4665        } else {
4666            0
4667        }
4668    }
4669
4670    pub fn buffer_line_for_row(
4671        &self,
4672        row: MultiBufferRow,
4673    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4674        let mut cursor = self.cursor::<Point>();
4675        let point = Point::new(row.0, 0);
4676        cursor.seek(&point);
4677        let region = cursor.region()?;
4678        let overshoot = point.min(region.range.end) - region.range.start;
4679        let buffer_point = region.buffer_range.start + overshoot;
4680        if buffer_point.row > region.buffer_range.end.row {
4681            return None;
4682        }
4683        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4684        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4685            .min(region.buffer_range.end);
4686        Some((region.buffer, line_start..line_end))
4687    }
4688
4689    pub fn max_point(&self) -> Point {
4690        self.text_summary().lines
4691    }
4692
4693    pub fn max_row(&self) -> MultiBufferRow {
4694        MultiBufferRow(self.text_summary().lines.row)
4695    }
4696
4697    pub fn text_summary(&self) -> TextSummary {
4698        self.diff_transforms.summary().output
4699    }
4700
4701    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4702    where
4703        D: TextDimension,
4704        O: ToOffset,
4705    {
4706        let range = range.start.to_offset(self)..range.end.to_offset(self);
4707        let mut cursor = self
4708            .diff_transforms
4709            .cursor::<Dimensions<usize, ExcerptOffset>>(());
4710        cursor.seek(&range.start, Bias::Right);
4711
4712        let Some(first_transform) = cursor.item() else {
4713            return D::from_text_summary(&TextSummary::default());
4714        };
4715
4716        let diff_transform_start = cursor.start().0;
4717        let diff_transform_end = cursor.end().0;
4718        let diff_start = range.start;
4719        let start_overshoot = diff_start - diff_transform_start;
4720        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4721
4722        let mut result = match first_transform {
4723            DiffTransform::BufferContent { .. } => {
4724                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4725                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4726                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4727            }
4728            DiffTransform::DeletedHunk {
4729                buffer_id,
4730                base_text_byte_range,
4731                has_trailing_newline,
4732                ..
4733            } => {
4734                let buffer_start = base_text_byte_range.start + start_overshoot;
4735                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4736                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4737                    panic!("{:?} is in non-existent deleted hunk", range.start)
4738                };
4739
4740                let include_trailing_newline =
4741                    *has_trailing_newline && range.end >= diff_transform_end;
4742                if include_trailing_newline {
4743                    buffer_end -= 1;
4744                }
4745
4746                let mut summary =
4747                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4748
4749                if include_trailing_newline {
4750                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4751                }
4752
4753                summary
4754            }
4755        };
4756        if range.end < diff_transform_end {
4757            return result;
4758        }
4759
4760        cursor.next();
4761        result.add_assign(&D::from_text_summary(
4762            &cursor.summary(&range.end, Bias::Right),
4763        ));
4764
4765        let Some(last_transform) = cursor.item() else {
4766            return result;
4767        };
4768
4769        let overshoot = range.end - cursor.start().0;
4770        let suffix = match last_transform {
4771            DiffTransform::BufferContent { .. } => {
4772                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4773                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4774            }
4775            DiffTransform::DeletedHunk {
4776                base_text_byte_range,
4777                buffer_id,
4778                has_trailing_newline,
4779                ..
4780            } => {
4781                let buffer_end = base_text_byte_range.start + overshoot;
4782                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4783                    panic!("{:?} is in non-existent deleted hunk", range.end)
4784                };
4785
4786                let mut suffix = base_text
4787                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4788                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4789                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4790                }
4791                suffix
4792            }
4793        };
4794
4795        result.add_assign(&suffix);
4796        result
4797    }
4798
4799    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4800    where
4801        D: TextDimension,
4802    {
4803        let mut summary = D::zero(());
4804        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
4805        cursor.seek(&range.start, Bias::Right);
4806        if let Some(excerpt) = cursor.item() {
4807            let mut end_before_newline = cursor.end();
4808            if excerpt.has_trailing_newline {
4809                end_before_newline -= ExcerptOffset::new(1);
4810            }
4811
4812            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4813            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4814            let end_in_excerpt =
4815                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4816            summary.add_assign(
4817                &excerpt
4818                    .buffer
4819                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4820            );
4821
4822            if range.end > end_before_newline {
4823                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4824            }
4825
4826            cursor.next();
4827        }
4828
4829        if range.end > *cursor.start() {
4830            summary.add_assign(
4831                &cursor
4832                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right)
4833                    .0,
4834            );
4835            if let Some(excerpt) = cursor.item() {
4836                range.end = cmp::max(*cursor.start(), range.end);
4837
4838                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4839                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4840                summary.add_assign(
4841                    &excerpt
4842                        .buffer
4843                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4844                );
4845            }
4846        }
4847
4848        summary
4849    }
4850
4851    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4852    where
4853        D: TextDimension + Ord + Sub<D, Output = D>,
4854    {
4855        self.summaries_for_anchors([anchor])[0]
4856    }
4857
4858    fn resolve_summary_for_anchor<D>(
4859        &self,
4860        anchor: &Anchor,
4861        excerpt_position: D,
4862        diff_transforms: &mut Cursor<
4863            DiffTransform,
4864            Dimensions<ExcerptDimension<D>, OutputDimension<D>>,
4865        >,
4866    ) -> D
4867    where
4868        D: TextDimension + Ord + Sub<D, Output = D>,
4869    {
4870        loop {
4871            let transform_end_position = diff_transforms.end().0.0;
4872            let at_transform_end =
4873                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4874            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4875                diff_transforms.next();
4876                continue;
4877            }
4878
4879            let mut position = diff_transforms.start().1.0;
4880            match diff_transforms.item() {
4881                Some(DiffTransform::DeletedHunk {
4882                    buffer_id,
4883                    base_text_byte_range,
4884                    ..
4885                }) => {
4886                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
4887                        && let Some(base_text) =
4888                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4889                        && base_text.can_resolve(diff_base_anchor)
4890                    {
4891                        let base_text_offset = diff_base_anchor.to_offset(base_text);
4892                        if base_text_offset >= base_text_byte_range.start
4893                            && base_text_offset <= base_text_byte_range.end
4894                        {
4895                            let position_in_hunk = base_text.text_summary_for_range::<D, _>(
4896                                base_text_byte_range.start..base_text_offset,
4897                            );
4898                            position.add_assign(&position_in_hunk);
4899                        } else if at_transform_end {
4900                            diff_transforms.next();
4901                            continue;
4902                        }
4903                    }
4904                }
4905                _ => {
4906                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4907                        diff_transforms.next();
4908                        continue;
4909                    }
4910                    let overshoot = excerpt_position - diff_transforms.start().0.0;
4911                    position.add_assign(&overshoot);
4912                }
4913            }
4914
4915            return position;
4916        }
4917    }
4918
4919    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4920        let mut cursor = self
4921            .excerpts
4922            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
4923        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4924
4925        cursor.seek(&Some(locator), Bias::Left);
4926        if cursor.item().is_none() && anchor.excerpt_id == ExcerptId::max() {
4927            cursor.prev();
4928        }
4929
4930        let mut position = cursor.start().1;
4931        if let Some(excerpt) = cursor.item()
4932            && (excerpt.id == anchor.excerpt_id || anchor.excerpt_id == ExcerptId::max())
4933        {
4934            let excerpt_buffer_start = excerpt
4935                .buffer
4936                .offset_for_anchor(&excerpt.range.context.start);
4937            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4938            let buffer_position = cmp::min(
4939                excerpt_buffer_end,
4940                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4941            );
4942            if buffer_position > excerpt_buffer_start {
4943                position.value += buffer_position - excerpt_buffer_start;
4944            }
4945        }
4946        position
4947    }
4948
4949    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
4950        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
4951            excerpt_id = *replacement;
4952        }
4953        excerpt_id
4954    }
4955
4956    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4957    where
4958        D: TextDimension + Ord + Sub<D, Output = D>,
4959        I: 'a + IntoIterator<Item = &'a Anchor>,
4960    {
4961        let mut anchors = anchors.into_iter().peekable();
4962        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
4963        let mut diff_transforms_cursor = self
4964            .diff_transforms
4965            .cursor::<Dimensions<ExcerptDimension<D>, OutputDimension<D>>>(());
4966        diff_transforms_cursor.next();
4967
4968        let mut summaries = Vec::new();
4969        while let Some(anchor) = anchors.peek() {
4970            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
4971
4972            let excerpt_anchors = anchors.peeking_take_while(|anchor| {
4973                self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id
4974            });
4975
4976            let locator = self.excerpt_locator_for_id(excerpt_id);
4977            cursor.seek_forward(locator, Bias::Left);
4978            if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
4979                cursor.prev();
4980            }
4981
4982            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4983            if let Some(excerpt) = cursor.item() {
4984                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
4985                    let position = self.resolve_summary_for_anchor(
4986                        &Anchor::min(),
4987                        excerpt_start_position,
4988                        &mut diff_transforms_cursor,
4989                    );
4990                    summaries.extend(excerpt_anchors.map(|_| position));
4991                    continue;
4992                }
4993                let excerpt_buffer_start =
4994                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4995                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4996                for (buffer_summary, anchor) in excerpt
4997                    .buffer
4998                    .summaries_for_anchors_with_payload::<D, _, _>(
4999                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
5000                    )
5001                {
5002                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5003                    let mut position = excerpt_start_position;
5004                    if summary > excerpt_buffer_start {
5005                        position.add_assign(&(summary - excerpt_buffer_start));
5006                    }
5007
5008                    if position > diff_transforms_cursor.start().0.0 {
5009                        diff_transforms_cursor
5010                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5011                    }
5012
5013                    summaries.push(self.resolve_summary_for_anchor(
5014                        anchor,
5015                        position,
5016                        &mut diff_transforms_cursor,
5017                    ));
5018                }
5019            } else {
5020                diff_transforms_cursor
5021                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5022                let position = self.resolve_summary_for_anchor(
5023                    &Anchor::max(),
5024                    excerpt_start_position,
5025                    &mut diff_transforms_cursor,
5026                );
5027                summaries.extend(excerpt_anchors.map(|_| position));
5028            }
5029        }
5030
5031        summaries
5032    }
5033
5034    pub fn dimensions_from_points<'a, D>(
5035        &'a self,
5036        points: impl 'a + IntoIterator<Item = Point>,
5037    ) -> impl 'a + Iterator<Item = D>
5038    where
5039        D: TextDimension + Sub<D, Output = D>,
5040    {
5041        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5042        cursor.seek(&DimensionPair {
5043            key: Point::default(),
5044            value: None,
5045        });
5046        let mut points = points.into_iter();
5047        iter::from_fn(move || {
5048            let point = points.next()?;
5049
5050            cursor.seek_forward(&DimensionPair {
5051                key: point,
5052                value: None,
5053            });
5054
5055            if let Some(region) = cursor.region() {
5056                let overshoot = point - region.range.start.key;
5057                let buffer_point = region.buffer_range.start.key + overshoot;
5058                let mut position = region.range.start.value.unwrap();
5059                position.add_assign(
5060                    &region
5061                        .buffer
5062                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5063                );
5064                if point == region.range.end.key && region.has_trailing_newline {
5065                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5066                }
5067                Some(position)
5068            } else {
5069                Some(D::from_text_summary(&self.text_summary()))
5070            }
5071        })
5072    }
5073
5074    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5075    where
5076        I: 'a + IntoIterator<Item = &'a Anchor>,
5077    {
5078        let mut anchors = anchors.into_iter().enumerate().peekable();
5079        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5080        cursor.next();
5081
5082        let mut result = Vec::new();
5083
5084        while let Some((_, anchor)) = anchors.peek() {
5085            let old_excerpt_id = anchor.excerpt_id;
5086
5087            // Find the location where this anchor's excerpt should be.
5088            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5089            cursor.seek_forward(&Some(old_locator), Bias::Left);
5090
5091            let next_excerpt = cursor.item();
5092            let prev_excerpt = cursor.prev_item();
5093
5094            // Process all of the anchors for this excerpt.
5095            while let Some((anchor_ix, &anchor)) =
5096                anchors.next_if(|(_, anchor)| anchor.excerpt_id == old_excerpt_id)
5097            {
5098                let mut anchor = anchor;
5099
5100                // Leave min and max anchors unchanged if invalid or
5101                // if the old excerpt still exists at this location
5102                let mut kept_position = next_excerpt
5103                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5104                    || old_excerpt_id == ExcerptId::max()
5105                    || old_excerpt_id == ExcerptId::min();
5106
5107                // If the old excerpt no longer exists at this location, then attempt to
5108                // find an equivalent position for this anchor in an adjacent excerpt.
5109                if !kept_position {
5110                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5111                        if excerpt.contains(&anchor) {
5112                            anchor.excerpt_id = excerpt.id;
5113                            kept_position = true;
5114                            break;
5115                        }
5116                    }
5117                }
5118
5119                // If there's no adjacent excerpt that contains the anchor's position,
5120                // then report that the anchor has lost its position.
5121                if !kept_position {
5122                    anchor = if let Some(excerpt) = next_excerpt {
5123                        let mut text_anchor = excerpt
5124                            .range
5125                            .context
5126                            .start
5127                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5128                        if text_anchor
5129                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5130                            .is_gt()
5131                        {
5132                            text_anchor = excerpt.range.context.end;
5133                        }
5134                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5135                    } else if let Some(excerpt) = prev_excerpt {
5136                        let mut text_anchor = excerpt
5137                            .range
5138                            .context
5139                            .end
5140                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5141                        if text_anchor
5142                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5143                            .is_lt()
5144                        {
5145                            text_anchor = excerpt.range.context.start;
5146                        }
5147                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5148                    } else if anchor.text_anchor.bias == Bias::Left {
5149                        Anchor::min()
5150                    } else {
5151                        Anchor::max()
5152                    };
5153                }
5154
5155                result.push((anchor_ix, anchor, kept_position));
5156            }
5157        }
5158        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5159        result
5160    }
5161
5162    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5163        self.anchor_at(position, Bias::Left)
5164    }
5165
5166    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5167        self.anchor_at(position, Bias::Right)
5168    }
5169
5170    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5171        let offset = position.to_offset(self);
5172
5173        // Find the given position in the diff transforms. Determine the corresponding
5174        // offset in the excerpts, and whether the position is within a deleted hunk.
5175        let mut diff_transforms = self
5176            .diff_transforms
5177            .cursor::<Dimensions<usize, ExcerptOffset>>(());
5178        diff_transforms.seek(&offset, Bias::Right);
5179
5180        if offset == diff_transforms.start().0
5181            && bias == Bias::Left
5182            && let Some(prev_item) = diff_transforms.prev_item()
5183            && let DiffTransform::DeletedHunk { .. } = prev_item
5184        {
5185            diff_transforms.prev();
5186        }
5187        let offset_in_transform = offset - diff_transforms.start().0;
5188        let mut excerpt_offset = diff_transforms.start().1;
5189        let mut diff_base_anchor = None;
5190        if let Some(DiffTransform::DeletedHunk {
5191            buffer_id,
5192            base_text_byte_range,
5193            has_trailing_newline,
5194            ..
5195        }) = diff_transforms.item()
5196        {
5197            let diff = self.diffs.get(buffer_id).expect("missing diff");
5198            if offset_in_transform > base_text_byte_range.len() {
5199                debug_assert!(*has_trailing_newline);
5200                bias = Bias::Right;
5201            } else {
5202                diff_base_anchor = Some(
5203                    diff.base_text()
5204                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5205                );
5206                bias = Bias::Left;
5207            }
5208        } else {
5209            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5210        };
5211
5212        let mut excerpts = self
5213            .excerpts
5214            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5215        excerpts.seek(&excerpt_offset, Bias::Right);
5216        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5217            excerpts.prev();
5218        }
5219        if let Some(excerpt) = excerpts.item() {
5220            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5221            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5222                overshoot -= 1;
5223                bias = Bias::Right;
5224            }
5225
5226            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5227            let text_anchor =
5228                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5229            let anchor = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor);
5230            match diff_base_anchor {
5231                Some(diff_base_anchor) => anchor.with_diff_base_anchor(diff_base_anchor),
5232                None => anchor,
5233            }
5234        } else if excerpt_offset.is_zero() && bias == Bias::Left {
5235            Anchor::min()
5236        } else {
5237            Anchor::max()
5238        }
5239    }
5240
5241    /// Returns an anchor for the given excerpt and text anchor,
5242    /// returns None if the excerpt_id is no longer valid.
5243    pub fn anchor_in_excerpt(
5244        &self,
5245        excerpt_id: ExcerptId,
5246        text_anchor: text::Anchor,
5247    ) -> Option<Anchor> {
5248        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5249        let excerpt = self.excerpt(excerpt_id)?;
5250        Some(Anchor::in_buffer(
5251            excerpt_id,
5252            excerpt.buffer_id,
5253            text_anchor,
5254        ))
5255    }
5256
5257    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5258        Some(self.excerpt(excerpt_id)?.range.context.clone())
5259    }
5260
5261    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5262        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5263            true
5264        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5265            excerpt.buffer.can_resolve(&anchor.text_anchor)
5266        } else {
5267            false
5268        }
5269    }
5270
5271    pub fn excerpts(
5272        &self,
5273    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5274        self.excerpts
5275            .iter()
5276            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5277    }
5278
5279    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5280        let excerpts = self.excerpts.cursor(());
5281        let diff_transforms = self.diff_transforms.cursor(());
5282        MultiBufferCursor {
5283            excerpts,
5284            diff_transforms,
5285            diffs: &self.diffs,
5286            cached_region: None,
5287        }
5288    }
5289
5290    pub fn excerpt_before(&self, excerpt_id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5291        let start_locator = self.excerpt_locator_for_id(excerpt_id);
5292        let mut excerpts = self
5293            .excerpts
5294            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(());
5295        excerpts.seek(&Some(start_locator), Bias::Left);
5296        excerpts.prev();
5297
5298        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(());
5299        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5300        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5301            diff_transforms.next();
5302        }
5303
5304        let excerpt = excerpts.item()?;
5305        Some(MultiBufferExcerpt {
5306            excerpt,
5307            offset: diff_transforms.start().output_dimension.0,
5308            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5309            excerpt_offset: excerpts.start().1.clone(),
5310            diff_transforms,
5311        })
5312    }
5313
5314    pub fn excerpt_boundaries_in_range<R, T>(
5315        &self,
5316        range: R,
5317    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5318    where
5319        R: RangeBounds<T>,
5320        T: ToOffset,
5321    {
5322        let start_offset;
5323        let start = match range.start_bound() {
5324            Bound::Included(start) => {
5325                start_offset = start.to_offset(self);
5326                Bound::Included(start_offset)
5327            }
5328            Bound::Excluded(_) => {
5329                panic!("not supported")
5330            }
5331            Bound::Unbounded => {
5332                start_offset = 0;
5333                Bound::Unbounded
5334            }
5335        };
5336        let end = match range.end_bound() {
5337            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5338            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5339            Bound::Unbounded => Bound::Unbounded,
5340        };
5341        let bounds = (start, end);
5342
5343        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5344        cursor.seek(&DimensionPair {
5345            key: start_offset,
5346            value: None,
5347        });
5348
5349        if cursor
5350            .region()
5351            .is_some_and(|region| bounds.contains(&region.range.start.key))
5352        {
5353            cursor.prev_excerpt();
5354        } else {
5355            cursor.seek_to_start_of_current_excerpt();
5356        }
5357        let mut prev_region = cursor.region();
5358
5359        cursor.next_excerpt();
5360
5361        iter::from_fn(move || {
5362            loop {
5363                if self.singleton {
5364                    return None;
5365                }
5366
5367                let next_region = cursor.region()?;
5368                cursor.next_excerpt();
5369                if !bounds.contains(&next_region.range.start.key) {
5370                    prev_region = Some(next_region);
5371                    continue;
5372                }
5373
5374                let next_region_start = next_region.range.start.value.unwrap();
5375                let next_region_end = if let Some(region) = cursor.region() {
5376                    region.range.start.value.unwrap()
5377                } else {
5378                    self.max_point()
5379                };
5380
5381                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5382                    id: region.excerpt.id,
5383                    buffer: region.excerpt.buffer.clone(),
5384                    buffer_id: region.excerpt.buffer_id,
5385                    range: region.excerpt.range.clone(),
5386                    end_row: MultiBufferRow(next_region_start.row),
5387                });
5388
5389                let next = ExcerptInfo {
5390                    id: next_region.excerpt.id,
5391                    buffer: next_region.excerpt.buffer.clone(),
5392                    buffer_id: next_region.excerpt.buffer_id,
5393                    range: next_region.excerpt.range.clone(),
5394                    end_row: if next_region.excerpt.has_trailing_newline {
5395                        MultiBufferRow(next_region_end.row - 1)
5396                    } else {
5397                        MultiBufferRow(next_region_end.row)
5398                    },
5399                };
5400
5401                let row = MultiBufferRow(next_region_start.row);
5402
5403                prev_region = Some(next_region);
5404
5405                return Some(ExcerptBoundary { row, prev, next });
5406            }
5407        })
5408    }
5409
5410    pub fn edit_count(&self) -> usize {
5411        self.edit_count
5412    }
5413
5414    pub fn non_text_state_update_count(&self) -> usize {
5415        self.non_text_state_update_count
5416    }
5417
5418    /// Returns the smallest enclosing bracket ranges containing the given range or
5419    /// None if no brackets contain range or the range is not contained in a single
5420    /// excerpt
5421    ///
5422    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5423    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5424        &self,
5425        range: Range<T>,
5426        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5427    ) -> Option<(Range<usize>, Range<usize>)> {
5428        let range = range.start.to_offset(self)..range.end.to_offset(self);
5429        let mut excerpt = self.excerpt_containing(range.clone())?;
5430        let buffer = excerpt.buffer();
5431        let excerpt_buffer_range = excerpt.buffer_range();
5432
5433        // Filter to ranges contained in the excerpt
5434        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5435            excerpt_buffer_range.contains(&open.start)
5436                && excerpt_buffer_range.contains(&close.end)
5437                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5438        };
5439
5440        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5441            excerpt.map_range_to_buffer(range),
5442            Some(&range_filter),
5443        )?;
5444
5445        Some((
5446            excerpt.map_range_from_buffer(open),
5447            excerpt.map_range_from_buffer(close),
5448        ))
5449    }
5450
5451    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5452    /// not contained in a single excerpt
5453    pub fn enclosing_bracket_ranges<T: ToOffset>(
5454        &self,
5455        range: Range<T>,
5456    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5457        let range = range.start.to_offset(self)..range.end.to_offset(self);
5458        let mut excerpt = self.excerpt_containing(range.clone())?;
5459
5460        Some(
5461            excerpt
5462                .buffer()
5463                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5464                .filter_map(move |pair| {
5465                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5466                        Some((
5467                            excerpt.map_range_from_buffer(pair.open_range),
5468                            excerpt.map_range_from_buffer(pair.close_range),
5469                        ))
5470                    } else {
5471                        None
5472                    }
5473                }),
5474        )
5475    }
5476
5477    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5478    /// not contained in a single excerpt
5479    pub fn text_object_ranges<T: ToOffset>(
5480        &self,
5481        range: Range<T>,
5482        options: TreeSitterOptions,
5483    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5484        let range = range.start.to_offset(self)..range.end.to_offset(self);
5485        self.excerpt_containing(range.clone())
5486            .map(|mut excerpt| {
5487                excerpt
5488                    .buffer()
5489                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5490                    .filter_map(move |(range, text_object)| {
5491                        if excerpt.contains_buffer_range(range.clone()) {
5492                            Some((excerpt.map_range_from_buffer(range), text_object))
5493                        } else {
5494                            None
5495                        }
5496                    })
5497            })
5498            .into_iter()
5499            .flatten()
5500    }
5501
5502    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5503    /// not contained in a single excerpt
5504    pub fn bracket_ranges<T: ToOffset>(
5505        &self,
5506        range: Range<T>,
5507    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5508        let range = range.start.to_offset(self)..range.end.to_offset(self);
5509        let mut excerpt = self.excerpt_containing(range.clone())?;
5510
5511        Some(
5512            excerpt
5513                .buffer()
5514                .bracket_ranges(excerpt.map_range_to_buffer(range))
5515                .filter_map(move |pair| {
5516                    let buffer_range = pair.open_range.start..pair.close_range.end;
5517                    if excerpt.contains_buffer_range(buffer_range) {
5518                        Some((
5519                            excerpt.map_range_from_buffer(pair.open_range),
5520                            excerpt.map_range_from_buffer(pair.close_range),
5521                        ))
5522                    } else {
5523                        None
5524                    }
5525                }),
5526        )
5527    }
5528
5529    pub fn redacted_ranges<'a, T: ToOffset>(
5530        &'a self,
5531        range: Range<T>,
5532        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5533    ) -> impl Iterator<Item = Range<usize>> + 'a {
5534        let range = range.start.to_offset(self)..range.end.to_offset(self);
5535        self.lift_buffer_metadata(range, move |buffer, range| {
5536            if redaction_enabled(buffer.file()) {
5537                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5538            } else {
5539                None
5540            }
5541        })
5542        .map(|(range, _, _)| range)
5543    }
5544
5545    pub fn runnable_ranges(
5546        &self,
5547        range: Range<Anchor>,
5548    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5549        let range = range.start.to_offset(self)..range.end.to_offset(self);
5550        self.lift_buffer_metadata(range, move |buffer, range| {
5551            Some(
5552                buffer
5553                    .runnable_ranges(range.clone())
5554                    .filter(move |runnable| {
5555                        runnable.run_range.start >= range.start
5556                            && runnable.run_range.end < range.end
5557                    })
5558                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5559            )
5560        })
5561        .map(|(run_range, runnable, _)| language::RunnableRange {
5562            run_range,
5563            ..runnable
5564        })
5565    }
5566
5567    pub fn line_indents(
5568        &self,
5569        start_row: MultiBufferRow,
5570        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5571    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5572        let max_point = self.max_point();
5573        let mut cursor = self.cursor::<Point>();
5574        cursor.seek(&Point::new(start_row.0, 0));
5575        iter::from_fn(move || {
5576            let mut region = cursor.region()?;
5577            while !buffer_filter(&region.excerpt.buffer) {
5578                cursor.next();
5579                region = cursor.region()?;
5580            }
5581            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5582            let buffer_start_row =
5583                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5584
5585            let buffer_end_row = if region.is_main_buffer
5586                && (region.has_trailing_newline || region.range.end == max_point)
5587            {
5588                region.buffer_range.end.row
5589            } else {
5590                region.buffer_range.end.row.saturating_sub(1)
5591            };
5592
5593            let line_indents = region
5594                .buffer
5595                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5596            cursor.next();
5597            Some(line_indents.map(move |(buffer_row, indent)| {
5598                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5599                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5600            }))
5601        })
5602        .flatten()
5603    }
5604
5605    pub fn reversed_line_indents(
5606        &self,
5607        end_row: MultiBufferRow,
5608        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5609    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5610        let max_point = self.max_point();
5611        let mut cursor = self.cursor::<Point>();
5612        cursor.seek(&Point::new(end_row.0, 0));
5613        iter::from_fn(move || {
5614            let mut region = cursor.region()?;
5615            while !buffer_filter(&region.excerpt.buffer) {
5616                cursor.prev();
5617                region = cursor.region()?;
5618            }
5619
5620            let buffer_start_row = region.buffer_range.start.row;
5621            let buffer_end_row = if region.is_main_buffer
5622                && (region.has_trailing_newline || region.range.end == max_point)
5623            {
5624                region.buffer_range.end.row + 1
5625            } else {
5626                region.buffer_range.end.row
5627            };
5628
5629            let overshoot = end_row.0 - region.range.start.row;
5630            let buffer_end_row =
5631                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5632
5633            let line_indents = region
5634                .buffer
5635                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5636            cursor.prev();
5637            Some(line_indents.map(move |(buffer_row, indent)| {
5638                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5639                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5640            }))
5641        })
5642        .flatten()
5643    }
5644
5645    pub async fn enclosing_indent(
5646        &self,
5647        mut target_row: MultiBufferRow,
5648    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5649        let max_row = MultiBufferRow(self.max_point().row);
5650        if target_row >= max_row {
5651            return None;
5652        }
5653
5654        let mut target_indent = self.line_indent_for_row(target_row);
5655
5656        // If the current row is at the start of an indented block, we want to return this
5657        // block as the enclosing indent.
5658        if !target_indent.is_line_empty() && target_row < max_row {
5659            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5660            if !next_line_indent.is_line_empty()
5661                && target_indent.raw_len() < next_line_indent.raw_len()
5662            {
5663                target_indent = next_line_indent;
5664                target_row.0 += 1;
5665            }
5666        }
5667
5668        const SEARCH_ROW_LIMIT: u32 = 25000;
5669        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5670        const YIELD_INTERVAL: u32 = 100;
5671
5672        let mut accessed_row_counter = 0;
5673
5674        // If there is a blank line at the current row, search for the next non indented lines
5675        if target_indent.is_line_empty() {
5676            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5677            let end =
5678                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5679
5680            let mut non_empty_line_above = None;
5681            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5682                if row < start {
5683                    break;
5684                }
5685                accessed_row_counter += 1;
5686                if accessed_row_counter == YIELD_INTERVAL {
5687                    accessed_row_counter = 0;
5688                    yield_now().await;
5689                }
5690                if !indent.is_line_empty() {
5691                    non_empty_line_above = Some((row, indent));
5692                    break;
5693                }
5694            }
5695
5696            let mut non_empty_line_below = None;
5697            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5698                if row > end {
5699                    break;
5700                }
5701                accessed_row_counter += 1;
5702                if accessed_row_counter == YIELD_INTERVAL {
5703                    accessed_row_counter = 0;
5704                    yield_now().await;
5705                }
5706                if !indent.is_line_empty() {
5707                    non_empty_line_below = Some((row, indent));
5708                    break;
5709                }
5710            }
5711
5712            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5713                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5714                    if above_indent.raw_len() >= below_indent.raw_len() {
5715                        (above_row, above_indent)
5716                    } else {
5717                        (below_row, below_indent)
5718                    }
5719                }
5720                (Some(above), None) => above,
5721                (None, Some(below)) => below,
5722                _ => return None,
5723            };
5724
5725            target_indent = indent;
5726            target_row = row;
5727        }
5728
5729        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5730        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5731
5732        let mut start_indent = None;
5733        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5734            if row < start {
5735                break;
5736            }
5737            accessed_row_counter += 1;
5738            if accessed_row_counter == YIELD_INTERVAL {
5739                accessed_row_counter = 0;
5740                yield_now().await;
5741            }
5742            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5743                start_indent = Some((row, indent));
5744                break;
5745            }
5746        }
5747        let (start_row, start_indent_size) = start_indent?;
5748
5749        let mut end_indent = (end, None);
5750        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5751            if row > end {
5752                break;
5753            }
5754            accessed_row_counter += 1;
5755            if accessed_row_counter == YIELD_INTERVAL {
5756                accessed_row_counter = 0;
5757                yield_now().await;
5758            }
5759            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5760                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5761                break;
5762            }
5763        }
5764        let (end_row, end_indent_size) = end_indent;
5765
5766        let indent = if let Some(end_indent_size) = end_indent_size {
5767            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5768                start_indent_size
5769            } else {
5770                end_indent_size
5771            }
5772        } else {
5773            start_indent_size
5774        };
5775
5776        Some((start_row..end_row, indent))
5777    }
5778
5779    pub fn indent_guides_in_range<T: ToPoint>(
5780        &self,
5781        range: Range<T>,
5782        ignore_disabled_for_language: bool,
5783        cx: &App,
5784    ) -> impl Iterator<Item = IndentGuide> {
5785        let range = range.start.to_point(self)..range.end.to_point(self);
5786        let start_row = MultiBufferRow(range.start.row);
5787        let end_row = MultiBufferRow(range.end.row);
5788
5789        let mut row_indents = self.line_indents(start_row, |buffer| {
5790            let settings =
5791                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5792            settings.indent_guides.enabled || ignore_disabled_for_language
5793        });
5794
5795        let mut result = Vec::new();
5796        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5797
5798        let mut prev_settings = None;
5799        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5800            if first_row > end_row {
5801                break;
5802            }
5803            let current_depth = indent_stack.len() as u32;
5804
5805            // Avoid retrieving the language settings repeatedly for every buffer row.
5806            if let Some((prev_buffer_id, _)) = &prev_settings
5807                && prev_buffer_id != &buffer.remote_id()
5808            {
5809                prev_settings.take();
5810            }
5811            let settings = &prev_settings
5812                .get_or_insert_with(|| {
5813                    (
5814                        buffer.remote_id(),
5815                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5816                    )
5817                })
5818                .1;
5819            let tab_size = settings.tab_size.get();
5820
5821            // When encountering empty, continue until found useful line indent
5822            // then add to the indent stack with the depth found
5823            let mut found_indent = false;
5824            let mut last_row = first_row;
5825            if line_indent.is_line_blank() {
5826                while !found_indent {
5827                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5828                        break;
5829                    };
5830                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5831                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5832                        break;
5833                    }
5834
5835                    if new_line_indent.is_line_blank() {
5836                        continue;
5837                    }
5838                    last_row = target_row.min(end_row);
5839                    line_indent = new_line_indent;
5840                    found_indent = true;
5841                    break;
5842                }
5843            } else {
5844                found_indent = true
5845            }
5846
5847            let depth = if found_indent {
5848                line_indent.len(tab_size) / tab_size
5849            } else {
5850                0
5851            };
5852
5853            match depth.cmp(&current_depth) {
5854                cmp::Ordering::Less => {
5855                    for _ in 0..(current_depth - depth) {
5856                        let mut indent = indent_stack.pop().unwrap();
5857                        if last_row != first_row {
5858                            // In this case, we landed on an empty row, had to seek forward,
5859                            // and discovered that the indent we where on is ending.
5860                            // This means that the last display row must
5861                            // be on line that ends this indent range, so we
5862                            // should display the range up to the first non-empty line
5863                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5864                        }
5865
5866                        result.push(indent)
5867                    }
5868                }
5869                cmp::Ordering::Greater => {
5870                    for next_depth in current_depth..depth {
5871                        indent_stack.push(IndentGuide {
5872                            buffer_id: buffer.remote_id(),
5873                            start_row: first_row,
5874                            end_row: last_row,
5875                            depth: next_depth,
5876                            tab_size,
5877                            settings: settings.indent_guides.clone(),
5878                        });
5879                    }
5880                }
5881                _ => {}
5882            }
5883
5884            for indent in indent_stack.iter_mut() {
5885                indent.end_row = last_row;
5886            }
5887        }
5888
5889        result.extend(indent_stack);
5890        result.into_iter()
5891    }
5892
5893    pub fn trailing_excerpt_update_count(&self) -> usize {
5894        self.trailing_excerpt_update_count
5895    }
5896
5897    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5898        self.point_to_buffer_offset(point)
5899            .and_then(|(buffer, _)| buffer.file())
5900    }
5901
5902    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5903        self.point_to_buffer_offset(point)
5904            .and_then(|(buffer, offset)| buffer.language_at(offset))
5905    }
5906
5907    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5908        self.excerpts
5909            .first()
5910            .map(|excerpt| &excerpt.buffer)
5911            .map(|buffer| {
5912                language_settings(
5913                    buffer.language().map(|language| language.name()),
5914                    buffer.file(),
5915                    cx,
5916                )
5917            })
5918            .unwrap_or_else(move || self.language_settings_at(0, cx))
5919    }
5920
5921    pub fn language_settings_at<'a, T: ToOffset>(
5922        &'a self,
5923        point: T,
5924        cx: &'a App,
5925    ) -> Cow<'a, LanguageSettings> {
5926        let mut language = None;
5927        let mut file = None;
5928        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5929            language = buffer.language_at(offset);
5930            file = buffer.file();
5931        }
5932        language_settings(language.map(|l| l.name()), file, cx)
5933    }
5934
5935    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5936        self.point_to_buffer_offset(point)
5937            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5938    }
5939
5940    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5941        self.point_to_buffer_offset(point)
5942            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5943            .unwrap_or_default()
5944    }
5945
5946    pub fn language_indent_size_at<T: ToOffset>(
5947        &self,
5948        position: T,
5949        cx: &App,
5950    ) -> Option<IndentSize> {
5951        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5952        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5953    }
5954
5955    pub fn is_dirty(&self) -> bool {
5956        self.is_dirty
5957    }
5958
5959    pub fn has_deleted_file(&self) -> bool {
5960        self.has_deleted_file
5961    }
5962
5963    pub fn has_conflict(&self) -> bool {
5964        self.has_conflict
5965    }
5966
5967    pub fn has_diagnostics(&self) -> bool {
5968        self.excerpts
5969            .iter()
5970            .any(|excerpt| excerpt.buffer.has_diagnostics())
5971    }
5972
5973    pub fn diagnostic_group(
5974        &self,
5975        buffer_id: BufferId,
5976        group_id: usize,
5977    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
5978        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
5979            if buffer.remote_id() != buffer_id {
5980                return None;
5981            };
5982            Some(
5983                buffer
5984                    .diagnostics_in_range(range, false)
5985                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
5986                    .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
5987            )
5988        })
5989        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
5990    }
5991
5992    pub fn diagnostics_in_range<'a, T>(
5993        &'a self,
5994        range: Range<T>,
5995    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, T>> + 'a
5996    where
5997        T: 'a
5998            + text::ToOffset
5999            + text::FromAnchor
6000            + TextDimension
6001            + Ord
6002            + Sub<T, Output = T>
6003            + fmt::Debug,
6004    {
6005        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6006            Some(
6007                buffer
6008                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6009                    .map(|entry| (entry.range, entry.diagnostic)),
6010            )
6011        })
6012        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6013    }
6014
6015    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6016        &'a self,
6017        range: Range<T>,
6018    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, T>)> + 'a
6019    where
6020        T: 'a
6021            + text::ToOffset
6022            + text::FromAnchor
6023            + TextDimension
6024            + Ord
6025            + Sub<T, Output = T>
6026            + fmt::Debug,
6027    {
6028        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6029            Some(
6030                buffer
6031                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6032                    .map(|entry| (entry.range, entry.diagnostic)),
6033            )
6034        })
6035        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6036    }
6037
6038    pub fn syntax_ancestor<T: ToOffset>(
6039        &self,
6040        range: Range<T>,
6041    ) -> Option<(tree_sitter::Node<'_>, Range<usize>)> {
6042        let range = range.start.to_offset(self)..range.end.to_offset(self);
6043        let mut excerpt = self.excerpt_containing(range.clone())?;
6044        let node = excerpt
6045            .buffer()
6046            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6047        let node_range = node.byte_range();
6048        if !excerpt.contains_buffer_range(node_range.clone()) {
6049            return None;
6050        };
6051        Some((node, excerpt.map_range_from_buffer(node_range)))
6052    }
6053
6054    pub fn syntax_next_sibling<T: ToOffset>(
6055        &self,
6056        range: Range<T>,
6057    ) -> Option<tree_sitter::Node<'_>> {
6058        let range = range.start.to_offset(self)..range.end.to_offset(self);
6059        let mut excerpt = self.excerpt_containing(range.clone())?;
6060        excerpt
6061            .buffer()
6062            .syntax_next_sibling(excerpt.map_range_to_buffer(range))
6063    }
6064
6065    pub fn syntax_prev_sibling<T: ToOffset>(
6066        &self,
6067        range: Range<T>,
6068    ) -> Option<tree_sitter::Node<'_>> {
6069        let range = range.start.to_offset(self)..range.end.to_offset(self);
6070        let mut excerpt = self.excerpt_containing(range.clone())?;
6071        excerpt
6072            .buffer()
6073            .syntax_prev_sibling(excerpt.map_range_to_buffer(range))
6074    }
6075
6076    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6077        let (excerpt_id, _, buffer) = self.as_singleton()?;
6078        let outline = buffer.outline(theme);
6079        Some(Outline::new(
6080            outline
6081                .items
6082                .into_iter()
6083                .flat_map(|item| {
6084                    Some(OutlineItem {
6085                        depth: item.depth,
6086                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6087                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6088                        text: item.text,
6089                        highlight_ranges: item.highlight_ranges,
6090                        name_ranges: item.name_ranges,
6091                        body_range: item.body_range.and_then(|body_range| {
6092                            Some(
6093                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6094                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6095                            )
6096                        }),
6097                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6098                            Some(
6099                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6100                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6101                            )
6102                        }),
6103                    })
6104                })
6105                .collect(),
6106        ))
6107    }
6108
6109    pub fn symbols_containing<T: ToOffset>(
6110        &self,
6111        offset: T,
6112        theme: Option<&SyntaxTheme>,
6113    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6114        let anchor = self.anchor_before(offset);
6115        let excerpt_id = anchor.excerpt_id;
6116        let excerpt = self.excerpt(excerpt_id)?;
6117        let buffer_id = excerpt.buffer_id;
6118        Some((
6119            buffer_id,
6120            excerpt
6121                .buffer
6122                .symbols_containing(anchor.text_anchor, theme)
6123                .into_iter()
6124                .flat_map(|item| {
6125                    Some(OutlineItem {
6126                        depth: item.depth,
6127                        range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
6128                        text: item.text,
6129                        highlight_ranges: item.highlight_ranges,
6130                        name_ranges: item.name_ranges,
6131                        body_range: item.body_range.map(|body_range| {
6132                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6133                        }),
6134                        annotation_range: item.annotation_range.map(|body_range| {
6135                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6136                        }),
6137                    })
6138                })
6139                .collect(),
6140        ))
6141    }
6142
6143    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6144        if id == ExcerptId::min() {
6145            Locator::min_ref()
6146        } else if id == ExcerptId::max() {
6147            Locator::max_ref()
6148        } else {
6149            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6150            cursor.seek(&id, Bias::Left);
6151            if let Some(entry) = cursor.item()
6152                && entry.id == id
6153            {
6154                return &entry.locator;
6155            }
6156            panic!("invalid excerpt id {id:?}")
6157        }
6158    }
6159
6160    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6161    fn excerpt_locators_for_ids(
6162        &self,
6163        ids: impl IntoIterator<Item = ExcerptId>,
6164    ) -> SmallVec<[Locator; 1]> {
6165        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6166        sorted_ids.sort_unstable();
6167        let mut locators = SmallVec::new();
6168
6169        while sorted_ids.last() == Some(&ExcerptId::max()) {
6170            sorted_ids.pop();
6171            if let Some(mapping) = self.excerpt_ids.last() {
6172                locators.push(mapping.locator.clone());
6173            }
6174        }
6175
6176        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6177        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6178            sorted_ids.next();
6179            if let Some(mapping) = self.excerpt_ids.first() {
6180                locators.push(mapping.locator.clone());
6181            }
6182        }
6183
6184        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6185        for id in sorted_ids {
6186            if cursor.seek_forward(&id, Bias::Left) {
6187                locators.push(cursor.item().unwrap().locator.clone());
6188            } else {
6189                panic!("invalid excerpt id {:?}", id);
6190            }
6191        }
6192
6193        locators.sort_unstable();
6194        locators
6195    }
6196
6197    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6198        Some(self.excerpt(excerpt_id)?.buffer_id)
6199    }
6200
6201    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6202        Some(&self.excerpt(excerpt_id)?.buffer)
6203    }
6204
6205    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6206        let mut cursor = self
6207            .excerpts
6208            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
6209        let locator = self.excerpt_locator_for_id(excerpt_id);
6210        let mut sought_exact = cursor.seek(&Some(locator), Bias::Left);
6211        if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
6212            sought_exact = true;
6213            cursor.prev();
6214        } else if excerpt_id == ExcerptId::min() {
6215            sought_exact = true;
6216        }
6217        if sought_exact {
6218            let start = cursor.start().1.clone();
6219            let end = cursor.end().1;
6220            let mut diff_transforms = self
6221                .diff_transforms
6222                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
6223            diff_transforms.seek(&start, Bias::Left);
6224            let overshoot = start.0 - diff_transforms.start().0.0;
6225            let start = diff_transforms.start().1.0 + overshoot;
6226            diff_transforms.seek(&end, Bias::Right);
6227            let overshoot = end.0 - diff_transforms.start().0.0;
6228            let end = diff_transforms.start().1.0 + overshoot;
6229            Some(start..end)
6230        } else {
6231            None
6232        }
6233    }
6234
6235    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6236        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6237        let locator = self.excerpt_locator_for_id(excerpt_id);
6238        cursor.seek(&Some(locator), Bias::Left);
6239        if let Some(excerpt) = cursor.item()
6240            && excerpt.id == excerpt_id
6241        {
6242            return Some(excerpt);
6243        } else if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
6244            cursor.prev();
6245            return cursor.item();
6246        }
6247        None
6248    }
6249
6250    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6251    pub fn excerpt_containing<T: ToOffset>(
6252        &self,
6253        range: Range<T>,
6254    ) -> Option<MultiBufferExcerpt<'_>> {
6255        let range = range.start.to_offset(self)..range.end.to_offset(self);
6256        let mut cursor = self.cursor::<usize>();
6257        cursor.seek(&range.start);
6258
6259        let start_excerpt = cursor.excerpt()?;
6260        if range.end != range.start {
6261            cursor.seek_forward(&range.end);
6262            if cursor.excerpt()?.id != start_excerpt.id {
6263                return None;
6264            }
6265        }
6266
6267        cursor.seek_to_start_of_current_excerpt();
6268        let region = cursor.region()?;
6269        let offset = region.range.start;
6270        let buffer_offset = start_excerpt.buffer_start_offset();
6271        let excerpt_offset = cursor.excerpts.start().clone();
6272        Some(MultiBufferExcerpt {
6273            diff_transforms: cursor.diff_transforms,
6274            excerpt: start_excerpt,
6275            offset,
6276            buffer_offset,
6277            excerpt_offset,
6278        })
6279    }
6280
6281    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
6282        if let Some(id) = anchor.buffer_id {
6283            return Some(id);
6284        }
6285        let excerpt = self.excerpt_containing(anchor..anchor)?;
6286        Some(excerpt.buffer_id())
6287    }
6288
6289    pub fn selections_in_range<'a>(
6290        &'a self,
6291        range: &'a Range<Anchor>,
6292        include_local: bool,
6293    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6294        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
6295        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6296        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6297        cursor.seek(start_locator, Bias::Left);
6298        cursor
6299            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6300            .flat_map(move |excerpt| {
6301                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6302                if excerpt.id == range.start.excerpt_id {
6303                    query_range.start = range.start.text_anchor;
6304                }
6305                if excerpt.id == range.end.excerpt_id {
6306                    query_range.end = range.end.text_anchor;
6307                }
6308
6309                excerpt
6310                    .buffer
6311                    .selections_in_range(query_range, include_local)
6312                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6313                        selections.map(move |selection| {
6314                            let mut start =
6315                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.start);
6316                            let mut end =
6317                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.end);
6318                            if range.start.cmp(&start, self).is_gt() {
6319                                start = range.start;
6320                            }
6321                            if range.end.cmp(&end, self).is_lt() {
6322                                end = range.end;
6323                            }
6324
6325                            (
6326                                replica_id,
6327                                line_mode,
6328                                cursor_shape,
6329                                Selection {
6330                                    id: selection.id,
6331                                    start,
6332                                    end,
6333                                    reversed: selection.reversed,
6334                                    goal: selection.goal,
6335                                },
6336                            )
6337                        })
6338                    })
6339            })
6340    }
6341
6342    pub fn show_headers(&self) -> bool {
6343        self.show_headers
6344    }
6345
6346    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6347        self.diffs.get(&buffer_id)
6348    }
6349
6350    /// Visually annotates a position or range with the `Debug` representation of a value. The
6351    /// callsite of this function is used as a key - previous annotations will be removed.
6352    #[cfg(debug_assertions)]
6353    #[track_caller]
6354    pub fn debug<V, R>(&self, ranges: &R, value: V)
6355    where
6356        R: debug::ToMultiBufferDebugRanges,
6357        V: std::fmt::Debug,
6358    {
6359        self.debug_with_key(std::panic::Location::caller(), ranges, value);
6360    }
6361
6362    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
6363    /// debug annotations with the same key will be removed. The key is also used to determine the
6364    /// annotation's color.
6365    #[cfg(debug_assertions)]
6366    #[track_caller]
6367    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
6368    where
6369        K: std::hash::Hash + 'static,
6370        R: debug::ToMultiBufferDebugRanges,
6371        V: std::fmt::Debug,
6372    {
6373        let text_ranges = ranges
6374            .to_multi_buffer_debug_ranges(self)
6375            .into_iter()
6376            .flat_map(|range| {
6377                self.range_to_buffer_ranges(range).into_iter().map(
6378                    |(buffer, range, _excerpt_id)| {
6379                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
6380                    },
6381                )
6382            })
6383            .collect();
6384        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
6385            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
6386        });
6387    }
6388
6389    // used by line_mode selections and tries to match vim behavior
6390    pub fn expand_to_line(&self, range: Range<Point>) -> Range<Point> {
6391        let new_start = MultiBufferPoint::new(range.start.row, 0);
6392        let new_end = if range.end.column > 0 {
6393            MultiBufferPoint::new(range.end.row, self.line_len(MultiBufferRow(range.end.row)))
6394        } else {
6395            range.end
6396        };
6397        new_start..new_end
6398    }
6399}
6400
6401#[cfg(any(test, feature = "test-support"))]
6402impl MultiBufferSnapshot {
6403    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6404        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
6405        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
6406        start..end
6407    }
6408
6409    #[cfg(any(test, feature = "test-support"))]
6410    fn check_invariants(&self) {
6411        let excerpts = self.excerpts.items(());
6412        let excerpt_ids = self.excerpt_ids.items(());
6413
6414        for (ix, excerpt) in excerpts.iter().enumerate() {
6415            if ix == 0 {
6416                if excerpt.locator <= Locator::min() {
6417                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6418                }
6419            } else if excerpt.locator <= excerpts[ix - 1].locator {
6420                panic!("excerpts are out-of-order: {:?}", excerpts);
6421            }
6422        }
6423
6424        for (ix, entry) in excerpt_ids.iter().enumerate() {
6425            if ix == 0 {
6426                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6427                    panic!("invalid first excerpt id {:?}", entry.id);
6428                }
6429            } else if entry.id <= excerpt_ids[ix - 1].id {
6430                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6431            }
6432        }
6433
6434        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6435            panic!(
6436                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6437                self.excerpts.summary().text.len,
6438                self.diff_transforms.summary().input,
6439                self.diff_transforms.items(()),
6440            );
6441        }
6442
6443        let mut prev_transform: Option<&DiffTransform> = None;
6444        for item in self.diff_transforms.iter() {
6445            if let DiffTransform::BufferContent {
6446                summary,
6447                inserted_hunk_info,
6448            } = item
6449            {
6450                if let Some(DiffTransform::BufferContent {
6451                    inserted_hunk_info: prev_inserted_hunk_info,
6452                    ..
6453                }) = prev_transform
6454                    && *inserted_hunk_info == *prev_inserted_hunk_info
6455                {
6456                    panic!(
6457                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6458                        self.diff_transforms.items(())
6459                    );
6460                }
6461                if summary.len == 0 && !self.is_empty() {
6462                    panic!("empty buffer content transform");
6463                }
6464            }
6465            prev_transform = Some(item);
6466        }
6467    }
6468}
6469
6470impl<'a, D> MultiBufferCursor<'a, D>
6471where
6472    D: TextDimension + Ord + Sub<D, Output = D>,
6473{
6474    fn seek(&mut self, position: &D) {
6475        self.cached_region.take();
6476        self.diff_transforms
6477            .seek(&OutputDimension(*position), Bias::Right);
6478        if self.diff_transforms.item().is_none()
6479            && *position == self.diff_transforms.start().output_dimension.0
6480        {
6481            self.diff_transforms.prev();
6482        }
6483
6484        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6485        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6486            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6487            excerpt_position.add_assign(&overshoot);
6488        }
6489
6490        self.excerpts
6491            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6492        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6493            self.excerpts.prev();
6494        }
6495    }
6496
6497    fn seek_forward(&mut self, position: &D) {
6498        self.cached_region.take();
6499        self.diff_transforms
6500            .seek_forward(&OutputDimension(*position), Bias::Right);
6501        if self.diff_transforms.item().is_none()
6502            && *position == self.diff_transforms.start().output_dimension.0
6503        {
6504            self.diff_transforms.prev();
6505        }
6506
6507        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6508        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6509        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6510            excerpt_position.add_assign(&overshoot);
6511        }
6512
6513        self.excerpts
6514            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6515        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6516            self.excerpts.prev();
6517        }
6518    }
6519
6520    fn next_excerpt(&mut self) {
6521        self.excerpts.next();
6522        self.seek_to_start_of_current_excerpt();
6523    }
6524
6525    fn prev_excerpt(&mut self) {
6526        self.excerpts.prev();
6527        self.seek_to_start_of_current_excerpt();
6528    }
6529
6530    fn seek_to_start_of_current_excerpt(&mut self) {
6531        self.cached_region.take();
6532        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6533        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6534            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6535            && self.diff_transforms.next_item().is_some()
6536        {
6537            self.diff_transforms.next();
6538        }
6539    }
6540
6541    fn next(&mut self) {
6542        self.cached_region.take();
6543        match self
6544            .diff_transforms
6545            .end()
6546            .excerpt_dimension
6547            .cmp(&self.excerpts.end())
6548        {
6549            cmp::Ordering::Less => self.diff_transforms.next(),
6550            cmp::Ordering::Greater => self.excerpts.next(),
6551            cmp::Ordering::Equal => {
6552                self.diff_transforms.next();
6553                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6554                    || self.diff_transforms.item().is_none()
6555                {
6556                    self.excerpts.next();
6557                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6558                    self.diff_transforms.item()
6559                    && self
6560                        .excerpts
6561                        .item()
6562                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6563                {
6564                    self.excerpts.next();
6565                }
6566            }
6567        }
6568    }
6569
6570    fn prev(&mut self) {
6571        self.cached_region.take();
6572        match self
6573            .diff_transforms
6574            .start()
6575            .excerpt_dimension
6576            .cmp(self.excerpts.start())
6577        {
6578            cmp::Ordering::Less => self.excerpts.prev(),
6579            cmp::Ordering::Greater => self.diff_transforms.prev(),
6580            cmp::Ordering::Equal => {
6581                self.diff_transforms.prev();
6582                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6583                    || self.diff_transforms.item().is_none()
6584                {
6585                    self.excerpts.prev();
6586                }
6587            }
6588        }
6589    }
6590
6591    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6592        if self.cached_region.is_none() {
6593            self.cached_region = self.build_region();
6594        }
6595        self.cached_region.clone()
6596    }
6597
6598    fn is_at_start_of_excerpt(&mut self) -> bool {
6599        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6600            return false;
6601        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6602            return true;
6603        }
6604
6605        self.diff_transforms.prev();
6606        let prev_transform = self.diff_transforms.item();
6607        self.diff_transforms.next();
6608
6609        prev_transform.is_none_or(|next_transform| {
6610            matches!(next_transform, DiffTransform::BufferContent { .. })
6611        })
6612    }
6613
6614    fn is_at_end_of_excerpt(&mut self) -> bool {
6615        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6616            return false;
6617        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6618            || self.diff_transforms.item().is_none()
6619        {
6620            return true;
6621        }
6622
6623        let next_transform = self.diff_transforms.next_item();
6624        next_transform.is_none_or(|next_transform| match next_transform {
6625            DiffTransform::BufferContent { .. } => true,
6626            DiffTransform::DeletedHunk { hunk_info, .. } => self
6627                .excerpts
6628                .item()
6629                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6630        })
6631    }
6632
6633    fn main_buffer_position(&self) -> Option<D> {
6634        let excerpt = self.excerpts.item()?;
6635        let buffer = &excerpt.buffer;
6636        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6637        let mut buffer_start = buffer_context_start;
6638        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6639        buffer_start.add_assign(&overshoot);
6640        Some(buffer_start)
6641    }
6642
6643    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6644        let excerpt = self.excerpts.item()?;
6645        match self.diff_transforms.item()? {
6646            DiffTransform::DeletedHunk {
6647                buffer_id,
6648                base_text_byte_range,
6649                has_trailing_newline,
6650                hunk_info,
6651                ..
6652            } => {
6653                let diff = self.diffs.get(buffer_id)?;
6654                let buffer = diff.base_text();
6655                let mut rope_cursor = buffer.as_rope().cursor(0);
6656                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6657                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6658                let mut buffer_end = buffer_start;
6659                buffer_end.add_assign(&buffer_range_len);
6660                let start = self.diff_transforms.start().output_dimension.0;
6661                let end = self.diff_transforms.end().output_dimension.0;
6662                Some(MultiBufferRegion {
6663                    buffer,
6664                    excerpt,
6665                    has_trailing_newline: *has_trailing_newline,
6666                    is_main_buffer: false,
6667                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6668                        hunk_info.hunk_secondary_status,
6669                    )),
6670                    buffer_range: buffer_start..buffer_end,
6671                    range: start..end,
6672                })
6673            }
6674            DiffTransform::BufferContent {
6675                inserted_hunk_info, ..
6676            } => {
6677                let buffer = &excerpt.buffer;
6678                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6679
6680                let mut start = self.diff_transforms.start().output_dimension.0;
6681                let mut buffer_start = buffer_context_start;
6682                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6683                    let overshoot =
6684                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6685                    start.add_assign(&overshoot);
6686                } else {
6687                    let overshoot =
6688                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6689                    buffer_start.add_assign(&overshoot);
6690                }
6691
6692                let mut end;
6693                let mut buffer_end;
6694                let has_trailing_newline;
6695                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6696                    let overshoot =
6697                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6698                    end = self.diff_transforms.end().output_dimension.0;
6699                    buffer_end = buffer_context_start;
6700                    buffer_end.add_assign(&overshoot);
6701                    has_trailing_newline = false;
6702                } else {
6703                    let overshoot =
6704                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6705                    end = self.diff_transforms.start().output_dimension.0;
6706                    end.add_assign(&overshoot);
6707                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6708                    has_trailing_newline = excerpt.has_trailing_newline;
6709                };
6710
6711                Some(MultiBufferRegion {
6712                    buffer,
6713                    excerpt,
6714                    has_trailing_newline,
6715                    is_main_buffer: true,
6716                    diff_hunk_status: inserted_hunk_info
6717                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6718                    buffer_range: buffer_start..buffer_end,
6719                    range: start..end,
6720                })
6721            }
6722        }
6723    }
6724
6725    fn excerpt(&self) -> Option<&'a Excerpt> {
6726        self.excerpts.item()
6727    }
6728}
6729
6730impl History {
6731    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6732        self.transaction_depth += 1;
6733        if self.transaction_depth == 1 {
6734            let id = self.next_transaction_id.tick();
6735            self.undo_stack.push(Transaction {
6736                id,
6737                buffer_transactions: Default::default(),
6738                first_edit_at: now,
6739                last_edit_at: now,
6740                suppress_grouping: false,
6741            });
6742            Some(id)
6743        } else {
6744            None
6745        }
6746    }
6747
6748    fn end_transaction(
6749        &mut self,
6750        now: Instant,
6751        buffer_transactions: HashMap<BufferId, TransactionId>,
6752    ) -> bool {
6753        assert_ne!(self.transaction_depth, 0);
6754        self.transaction_depth -= 1;
6755        if self.transaction_depth == 0 {
6756            if buffer_transactions.is_empty() {
6757                self.undo_stack.pop();
6758                false
6759            } else {
6760                self.redo_stack.clear();
6761                let transaction = self.undo_stack.last_mut().unwrap();
6762                transaction.last_edit_at = now;
6763                for (buffer_id, transaction_id) in buffer_transactions {
6764                    transaction
6765                        .buffer_transactions
6766                        .entry(buffer_id)
6767                        .or_insert(transaction_id);
6768                }
6769                true
6770            }
6771        } else {
6772            false
6773        }
6774    }
6775
6776    fn push_transaction<'a, T>(
6777        &mut self,
6778        buffer_transactions: T,
6779        now: Instant,
6780        cx: &Context<MultiBuffer>,
6781    ) where
6782        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6783    {
6784        assert_eq!(self.transaction_depth, 0);
6785        let transaction = Transaction {
6786            id: self.next_transaction_id.tick(),
6787            buffer_transactions: buffer_transactions
6788                .into_iter()
6789                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6790                .collect(),
6791            first_edit_at: now,
6792            last_edit_at: now,
6793            suppress_grouping: false,
6794        };
6795        if !transaction.buffer_transactions.is_empty() {
6796            self.undo_stack.push(transaction);
6797            self.redo_stack.clear();
6798        }
6799    }
6800
6801    fn finalize_last_transaction(&mut self) {
6802        if let Some(transaction) = self.undo_stack.last_mut() {
6803            transaction.suppress_grouping = true;
6804        }
6805    }
6806
6807    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6808        if let Some(ix) = self
6809            .undo_stack
6810            .iter()
6811            .rposition(|transaction| transaction.id == transaction_id)
6812        {
6813            Some(self.undo_stack.remove(ix))
6814        } else if let Some(ix) = self
6815            .redo_stack
6816            .iter()
6817            .rposition(|transaction| transaction.id == transaction_id)
6818        {
6819            Some(self.redo_stack.remove(ix))
6820        } else {
6821            None
6822        }
6823    }
6824
6825    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6826        self.undo_stack
6827            .iter()
6828            .find(|transaction| transaction.id == transaction_id)
6829            .or_else(|| {
6830                self.redo_stack
6831                    .iter()
6832                    .find(|transaction| transaction.id == transaction_id)
6833            })
6834    }
6835
6836    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6837        self.undo_stack
6838            .iter_mut()
6839            .find(|transaction| transaction.id == transaction_id)
6840            .or_else(|| {
6841                self.redo_stack
6842                    .iter_mut()
6843                    .find(|transaction| transaction.id == transaction_id)
6844            })
6845    }
6846
6847    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6848        assert_eq!(self.transaction_depth, 0);
6849        if let Some(transaction) = self.undo_stack.pop() {
6850            self.redo_stack.push(transaction);
6851            self.redo_stack.last_mut()
6852        } else {
6853            None
6854        }
6855    }
6856
6857    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6858        assert_eq!(self.transaction_depth, 0);
6859        if let Some(transaction) = self.redo_stack.pop() {
6860            self.undo_stack.push(transaction);
6861            self.undo_stack.last_mut()
6862        } else {
6863            None
6864        }
6865    }
6866
6867    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6868        let ix = self
6869            .undo_stack
6870            .iter()
6871            .rposition(|transaction| transaction.id == transaction_id)?;
6872        let transaction = self.undo_stack.remove(ix);
6873        self.redo_stack.push(transaction);
6874        self.redo_stack.last()
6875    }
6876
6877    fn group(&mut self) -> Option<TransactionId> {
6878        let mut count = 0;
6879        let mut transactions = self.undo_stack.iter();
6880        if let Some(mut transaction) = transactions.next_back() {
6881            while let Some(prev_transaction) = transactions.next_back() {
6882                if !prev_transaction.suppress_grouping
6883                    && transaction.first_edit_at - prev_transaction.last_edit_at
6884                        <= self.group_interval
6885                {
6886                    transaction = prev_transaction;
6887                    count += 1;
6888                } else {
6889                    break;
6890                }
6891            }
6892        }
6893        self.group_trailing(count)
6894    }
6895
6896    fn group_until(&mut self, transaction_id: TransactionId) {
6897        let mut count = 0;
6898        for transaction in self.undo_stack.iter().rev() {
6899            if transaction.id == transaction_id {
6900                self.group_trailing(count);
6901                break;
6902            } else if transaction.suppress_grouping {
6903                break;
6904            } else {
6905                count += 1;
6906            }
6907        }
6908    }
6909
6910    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6911        let new_len = self.undo_stack.len() - n;
6912        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6913        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6914            if let Some(transaction) = transactions_to_merge.last() {
6915                last_transaction.last_edit_at = transaction.last_edit_at;
6916            }
6917            for to_merge in transactions_to_merge {
6918                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6919                    last_transaction
6920                        .buffer_transactions
6921                        .entry(*buffer_id)
6922                        .or_insert(*transaction_id);
6923                }
6924            }
6925        }
6926
6927        self.undo_stack.truncate(new_len);
6928        self.undo_stack.last().map(|t| t.id)
6929    }
6930}
6931
6932impl Excerpt {
6933    fn new(
6934        id: ExcerptId,
6935        locator: Locator,
6936        buffer_id: BufferId,
6937        buffer: BufferSnapshot,
6938        range: ExcerptRange<text::Anchor>,
6939        has_trailing_newline: bool,
6940    ) -> Self {
6941        Excerpt {
6942            id,
6943            locator,
6944            max_buffer_row: range.context.end.to_point(&buffer).row,
6945            text_summary: buffer
6946                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6947            buffer_id,
6948            buffer,
6949            range,
6950            has_trailing_newline,
6951        }
6952    }
6953
6954    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6955        let content_start = self.range.context.start.to_offset(&self.buffer);
6956        let chunks_start = content_start + range.start;
6957        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6958
6959        let footer_height = if self.has_trailing_newline
6960            && range.start <= self.text_summary.len
6961            && range.end > self.text_summary.len
6962        {
6963            1
6964        } else {
6965            0
6966        };
6967
6968        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
6969
6970        ExcerptChunks {
6971            excerpt_id: self.id,
6972            content_chunks,
6973            footer_height,
6974        }
6975    }
6976
6977    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
6978        let content_start = self.range.context.start.to_offset(&self.buffer);
6979        let chunks_start = content_start + range.start;
6980        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6981        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
6982        excerpt_chunks.footer_height = if self.has_trailing_newline
6983            && range.start <= self.text_summary.len
6984            && range.end > self.text_summary.len
6985        {
6986            1
6987        } else {
6988            0
6989        };
6990    }
6991
6992    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
6993        if text_anchor
6994            .cmp(&self.range.context.start, &self.buffer)
6995            .is_lt()
6996        {
6997            self.range.context.start
6998        } else if text_anchor
6999            .cmp(&self.range.context.end, &self.buffer)
7000            .is_gt()
7001        {
7002            self.range.context.end
7003        } else {
7004            text_anchor
7005        }
7006    }
7007
7008    fn contains(&self, anchor: &Anchor) -> bool {
7009        (anchor.buffer_id == None || anchor.buffer_id == Some(self.buffer_id))
7010            && self
7011                .range
7012                .context
7013                .start
7014                .cmp(&anchor.text_anchor, &self.buffer)
7015                .is_le()
7016            && self
7017                .range
7018                .context
7019                .end
7020                .cmp(&anchor.text_anchor, &self.buffer)
7021                .is_ge()
7022    }
7023
7024    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7025    fn buffer_start_offset(&self) -> usize {
7026        self.range.context.start.to_offset(&self.buffer)
7027    }
7028
7029    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7030    fn buffer_end_offset(&self) -> usize {
7031        self.buffer_start_offset() + self.text_summary.len
7032    }
7033}
7034
7035impl<'a> MultiBufferExcerpt<'a> {
7036    pub fn id(&self) -> ExcerptId {
7037        self.excerpt.id
7038    }
7039
7040    pub fn buffer_id(&self) -> BufferId {
7041        self.excerpt.buffer_id
7042    }
7043
7044    pub fn start_anchor(&self) -> Anchor {
7045        Anchor::in_buffer(
7046            self.excerpt.id,
7047            self.excerpt.buffer_id,
7048            self.excerpt.range.context.start,
7049        )
7050    }
7051
7052    pub fn end_anchor(&self) -> Anchor {
7053        Anchor::in_buffer(
7054            self.excerpt.id,
7055            self.excerpt.buffer_id,
7056            self.excerpt.range.context.end,
7057        )
7058    }
7059
7060    pub fn buffer(&self) -> &'a BufferSnapshot {
7061        &self.excerpt.buffer
7062    }
7063
7064    pub fn buffer_range(&self) -> Range<usize> {
7065        self.buffer_offset
7066            ..self
7067                .excerpt
7068                .range
7069                .context
7070                .end
7071                .to_offset(&self.excerpt.buffer.text)
7072    }
7073
7074    pub fn start_offset(&self) -> usize {
7075        self.offset
7076    }
7077
7078    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7079    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7080        self.map_range_to_buffer(offset..offset).start
7081    }
7082
7083    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7084    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7085        self.diff_transforms
7086            .seek(&OutputDimension(range.start), Bias::Right);
7087        let start = self.map_offset_to_buffer_internal(range.start);
7088        let end = if range.end > range.start {
7089            self.diff_transforms
7090                .seek_forward(&OutputDimension(range.end), Bias::Right);
7091            self.map_offset_to_buffer_internal(range.end)
7092        } else {
7093            start
7094        };
7095        start..end
7096    }
7097
7098    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7099        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7100        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7101            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7102        };
7103        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7104        self.buffer_offset + offset_in_excerpt
7105    }
7106
7107    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7108    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7109        self.map_range_from_buffer(buffer_offset..buffer_offset)
7110            .start
7111    }
7112
7113    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7114    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7115        if buffer_range.start < self.buffer_offset {
7116            log::warn!(
7117                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7118            );
7119            return buffer_range;
7120        }
7121        let overshoot = buffer_range.start - self.buffer_offset;
7122        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7123        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7124        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7125            log::warn!(
7126                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7127            );
7128            return buffer_range;
7129        }
7130        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7131        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7132
7133        let end = if buffer_range.end > buffer_range.start {
7134            let overshoot = buffer_range.end - self.buffer_offset;
7135            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7136            self.diff_transforms
7137                .seek_forward(&excerpt_offset, Bias::Right);
7138            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7139            self.diff_transforms.start().output_dimension.0 + overshoot
7140        } else {
7141            start
7142        };
7143
7144        start..end
7145    }
7146
7147    /// Returns true if the entirety of the given range is in the buffer's excerpt
7148    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7149        range.start >= self.excerpt.buffer_start_offset()
7150            && range.end <= self.excerpt.buffer_end_offset()
7151    }
7152
7153    pub fn max_buffer_row(&self) -> u32 {
7154        self.excerpt.max_buffer_row
7155    }
7156}
7157
7158impl ExcerptId {
7159    pub fn min() -> Self {
7160        Self(0)
7161    }
7162
7163    pub fn max() -> Self {
7164        Self(u32::MAX)
7165    }
7166
7167    pub fn to_proto(self) -> u64 {
7168        self.0 as _
7169    }
7170
7171    pub fn from_proto(proto: u64) -> Self {
7172        Self(proto as _)
7173    }
7174
7175    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7176        let a = snapshot.excerpt_locator_for_id(*self);
7177        let b = snapshot.excerpt_locator_for_id(*other);
7178        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7179    }
7180}
7181
7182impl From<ExcerptId> for usize {
7183    fn from(val: ExcerptId) -> Self {
7184        val.0 as usize
7185    }
7186}
7187
7188impl fmt::Debug for Excerpt {
7189    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7190        f.debug_struct("Excerpt")
7191            .field("id", &self.id)
7192            .field("locator", &self.locator)
7193            .field("buffer_id", &self.buffer_id)
7194            .field("range", &self.range)
7195            .field("text_summary", &self.text_summary)
7196            .field("has_trailing_newline", &self.has_trailing_newline)
7197            .finish()
7198    }
7199}
7200
7201impl sum_tree::Item for Excerpt {
7202    type Summary = ExcerptSummary;
7203
7204    fn summary(&self, _cx: ()) -> Self::Summary {
7205        let mut text = self.text_summary;
7206        if self.has_trailing_newline {
7207            text += TextSummary::from("\n");
7208        }
7209        ExcerptSummary {
7210            excerpt_id: self.id,
7211            excerpt_locator: self.locator.clone(),
7212            widest_line_number: self.max_buffer_row,
7213            text,
7214        }
7215    }
7216}
7217
7218impl sum_tree::Item for ExcerptIdMapping {
7219    type Summary = ExcerptId;
7220
7221    fn summary(&self, _cx: ()) -> Self::Summary {
7222        self.id
7223    }
7224}
7225
7226impl sum_tree::KeyedItem for ExcerptIdMapping {
7227    type Key = ExcerptId;
7228
7229    fn key(&self) -> Self::Key {
7230        self.id
7231    }
7232}
7233
7234impl DiffTransform {
7235    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7236        match self {
7237            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7238            DiffTransform::BufferContent {
7239                inserted_hunk_info, ..
7240            } => *inserted_hunk_info,
7241        }
7242    }
7243}
7244
7245impl sum_tree::Item for DiffTransform {
7246    type Summary = DiffTransformSummary;
7247
7248    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7249        match self {
7250            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7251                input: *summary,
7252                output: *summary,
7253            },
7254            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7255                input: TextSummary::default(),
7256                output: *summary,
7257            },
7258        }
7259    }
7260}
7261
7262impl DiffTransformSummary {
7263    fn excerpt_len(&self) -> ExcerptOffset {
7264        ExcerptOffset::new(self.input.len)
7265    }
7266}
7267
7268impl sum_tree::ContextLessSummary for DiffTransformSummary {
7269    fn zero() -> Self {
7270        DiffTransformSummary {
7271            input: TextSummary::default(),
7272            output: TextSummary::default(),
7273        }
7274    }
7275
7276    fn add_summary(&mut self, other: &Self) {
7277        self.input += other.input;
7278        self.output += other.output;
7279    }
7280}
7281
7282impl sum_tree::ContextLessSummary for ExcerptId {
7283    fn zero() -> Self {
7284        Self(0)
7285    }
7286
7287    fn add_summary(&mut self, summary: &Self) {
7288        *self = cmp::max(*self, *summary);
7289    }
7290}
7291
7292impl sum_tree::ContextLessSummary for ExcerptSummary {
7293    fn zero() -> Self {
7294        Self::default()
7295    }
7296
7297    fn add_summary(&mut self, summary: &Self) {
7298        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7299        self.excerpt_locator = summary.excerpt_locator.clone();
7300        Summary::add_summary(&mut self.text, &summary.text, ());
7301        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7302    }
7303}
7304
7305impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7306    fn zero(_cx: ()) -> Self {
7307        Default::default()
7308    }
7309
7310    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7311        self.value += summary.text.len;
7312    }
7313}
7314
7315impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7316    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7317        Ord::cmp(&self.value, &cursor_location.text.len)
7318    }
7319}
7320
7321impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7322    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
7323        Ord::cmp(&Some(self), cursor_location)
7324    }
7325}
7326
7327impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7328    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7329        Ord::cmp(self, &cursor_location.excerpt_locator)
7330    }
7331}
7332
7333impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7334    fn zero(_cx: ()) -> Self {
7335        Default::default()
7336    }
7337
7338    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7339        self.value += summary.text.lines;
7340    }
7341}
7342
7343impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7344    for ExcerptDimension<D>
7345{
7346    fn zero(_: ()) -> Self {
7347        ExcerptDimension(D::default())
7348    }
7349
7350    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7351        self.0.add_assign(&D::from_text_summary(&summary.text))
7352    }
7353}
7354
7355impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7356    fn zero(_cx: ()) -> Self {
7357        Default::default()
7358    }
7359
7360    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7361        *self = Some(&summary.excerpt_locator);
7362    }
7363}
7364
7365impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7366    fn zero(_cx: ()) -> Self {
7367        Default::default()
7368    }
7369
7370    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7371        *self = Some(summary.excerpt_id);
7372    }
7373}
7374
7375#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7376struct ExcerptDimension<T>(T);
7377
7378#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7379struct OutputDimension<T>(T);
7380
7381impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7382    fn zero(_: ()) -> Self {
7383        ExcerptOffset::new(0)
7384    }
7385
7386    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7387        self.value += summary.input.len;
7388    }
7389}
7390
7391impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7392    fn zero(_: ()) -> Self {
7393        ExcerptPoint::new(0, 0)
7394    }
7395
7396    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7397        self.value += summary.input.lines;
7398    }
7399}
7400
7401impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7402    for ExcerptDimension<D>
7403{
7404    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
7405        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7406    }
7407}
7408
7409impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7410    for ExcerptDimension<D>
7411{
7412    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7413        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7414    }
7415}
7416
7417impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7418    fn zero(_: ()) -> Self {
7419        ExcerptDimension(D::default())
7420    }
7421
7422    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7423        self.0.add_assign(&D::from_text_summary(&summary.input))
7424    }
7425}
7426
7427impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7428    for OutputDimension<D>
7429{
7430    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7431        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7432    }
7433}
7434
7435impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7436    fn zero(_: ()) -> Self {
7437        OutputDimension(D::default())
7438    }
7439
7440    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7441        self.0.add_assign(&D::from_text_summary(&summary.output))
7442    }
7443}
7444
7445impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7446    fn zero(_: ()) -> Self {
7447        TextSummary::default()
7448    }
7449
7450    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7451        *self += summary.output
7452    }
7453}
7454
7455impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7456    fn zero(_: ()) -> Self {
7457        0
7458    }
7459
7460    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7461        *self += summary.output.len
7462    }
7463}
7464
7465impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7466    fn zero(_: ()) -> Self {
7467        Point::new(0, 0)
7468    }
7469
7470    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7471        *self += summary.output.lines
7472    }
7473}
7474
7475impl MultiBufferRows<'_> {
7476    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7477        self.point = Point::new(row, 0);
7478        self.cursor.seek(&self.point);
7479    }
7480}
7481
7482impl Iterator for MultiBufferRows<'_> {
7483    type Item = RowInfo;
7484
7485    fn next(&mut self) -> Option<Self::Item> {
7486        if self.is_empty && self.point.row == 0 {
7487            self.point += Point::new(1, 0);
7488            return Some(RowInfo {
7489                buffer_id: None,
7490                buffer_row: Some(0),
7491                multibuffer_row: Some(MultiBufferRow(0)),
7492                diff_status: None,
7493                expand_info: None,
7494            });
7495        }
7496
7497        let mut region = self.cursor.region()?;
7498        while self.point >= region.range.end {
7499            self.cursor.next();
7500            if let Some(next_region) = self.cursor.region() {
7501                region = next_region;
7502            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7503                let multibuffer_row = MultiBufferRow(self.point.row);
7504                let last_excerpt = self
7505                    .cursor
7506                    .excerpts
7507                    .item()
7508                    .or(self.cursor.excerpts.prev_item())?;
7509                let last_row = last_excerpt
7510                    .range
7511                    .context
7512                    .end
7513                    .to_point(&last_excerpt.buffer)
7514                    .row;
7515
7516                let first_row = last_excerpt
7517                    .range
7518                    .context
7519                    .start
7520                    .to_point(&last_excerpt.buffer)
7521                    .row;
7522
7523                let expand_info = if self.is_singleton {
7524                    None
7525                } else {
7526                    let needs_expand_up = first_row == last_row
7527                        && last_row > 0
7528                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7529                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
7530
7531                    if needs_expand_up && needs_expand_down {
7532                        Some(ExpandExcerptDirection::UpAndDown)
7533                    } else if needs_expand_up {
7534                        Some(ExpandExcerptDirection::Up)
7535                    } else if needs_expand_down {
7536                        Some(ExpandExcerptDirection::Down)
7537                    } else {
7538                        None
7539                    }
7540                    .map(|direction| ExpandInfo {
7541                        direction,
7542                        excerpt_id: last_excerpt.id,
7543                    })
7544                };
7545                self.point += Point::new(1, 0);
7546                return Some(RowInfo {
7547                    buffer_id: Some(last_excerpt.buffer_id),
7548                    buffer_row: Some(last_row),
7549                    multibuffer_row: Some(multibuffer_row),
7550                    diff_status: None,
7551                    expand_info,
7552                });
7553            } else {
7554                return None;
7555            };
7556        }
7557
7558        let overshoot = self.point - region.range.start;
7559        let buffer_point = region.buffer_range.start + overshoot;
7560        let expand_info = if self.is_singleton {
7561            None
7562        } else {
7563            let needs_expand_up = self.point.row == region.range.start.row
7564                && self.cursor.is_at_start_of_excerpt()
7565                && buffer_point.row > 0;
7566            let needs_expand_down = (region.excerpt.has_trailing_newline
7567                && self.point.row + 1 == region.range.end.row
7568                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7569                && self.cursor.is_at_end_of_excerpt()
7570                && buffer_point.row < region.buffer.max_point().row;
7571
7572            if needs_expand_up && needs_expand_down {
7573                Some(ExpandExcerptDirection::UpAndDown)
7574            } else if needs_expand_up {
7575                Some(ExpandExcerptDirection::Up)
7576            } else if needs_expand_down {
7577                Some(ExpandExcerptDirection::Down)
7578            } else {
7579                None
7580            }
7581            .map(|direction| ExpandInfo {
7582                direction,
7583                excerpt_id: region.excerpt.id,
7584            })
7585        };
7586
7587        let result = Some(RowInfo {
7588            buffer_id: Some(region.buffer.remote_id()),
7589            buffer_row: Some(buffer_point.row),
7590            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7591            diff_status: region
7592                .diff_hunk_status
7593                .filter(|_| self.point < region.range.end),
7594            expand_info,
7595        });
7596        self.point += Point::new(1, 0);
7597        result
7598    }
7599}
7600
7601impl<'a> MultiBufferChunks<'a> {
7602    pub fn offset(&self) -> usize {
7603        self.range.start
7604    }
7605
7606    pub fn seek(&mut self, range: Range<usize>) {
7607        self.diff_transforms.seek(&range.end, Bias::Right);
7608        let mut excerpt_end = self.diff_transforms.start().1;
7609        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7610            let overshoot = range.end - self.diff_transforms.start().0;
7611            excerpt_end.value += overshoot;
7612        }
7613
7614        self.diff_transforms.seek(&range.start, Bias::Right);
7615        let mut excerpt_start = self.diff_transforms.start().1;
7616        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7617            let overshoot = range.start - self.diff_transforms.start().0;
7618            excerpt_start.value += overshoot;
7619        }
7620
7621        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7622        self.buffer_chunk.take();
7623        self.range = range;
7624    }
7625
7626    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7627        self.excerpt_offset_range = new_range.clone();
7628        self.excerpts.seek(&new_range.start, Bias::Right);
7629        if let Some(excerpt) = self.excerpts.item() {
7630            let excerpt_start = *self.excerpts.start();
7631            if let Some(excerpt_chunks) = self
7632                .excerpt_chunks
7633                .as_mut()
7634                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7635            {
7636                excerpt.seek_chunks(
7637                    excerpt_chunks,
7638                    (self.excerpt_offset_range.start - excerpt_start).value
7639                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7640                );
7641            } else {
7642                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7643                    (self.excerpt_offset_range.start - excerpt_start).value
7644                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7645                    self.language_aware,
7646                ));
7647            }
7648        } else {
7649            self.excerpt_chunks = None;
7650        }
7651    }
7652
7653    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7654        loop {
7655            if self.excerpt_offset_range.is_empty() {
7656                return None;
7657            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7658                self.excerpt_offset_range.start.value += chunk.text.len();
7659                return Some(chunk);
7660            } else {
7661                self.excerpts.next();
7662                let excerpt = self.excerpts.item()?;
7663                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7664                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7665                    self.language_aware,
7666                ));
7667            }
7668        }
7669    }
7670}
7671
7672impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7673    type Item = &'a str;
7674
7675    fn next(&mut self) -> Option<Self::Item> {
7676        let mut region = self.cursor.region()?;
7677        if self.offset == region.range.start {
7678            self.cursor.prev();
7679            region = self.cursor.region()?;
7680            let start_overshoot = self.start.saturating_sub(region.range.start);
7681            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7682                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7683            ));
7684        }
7685
7686        if self.offset == region.range.end && region.has_trailing_newline {
7687            self.offset -= 1;
7688            Some("\n")
7689        } else {
7690            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7691            self.offset -= chunk.len();
7692            Some(chunk)
7693        }
7694    }
7695}
7696
7697impl<'a> Iterator for MultiBufferChunks<'a> {
7698    type Item = Chunk<'a>;
7699
7700    fn next(&mut self) -> Option<Chunk<'a>> {
7701        if self.range.start >= self.range.end {
7702            return None;
7703        }
7704        if self.range.start == self.diff_transforms.end().0 {
7705            self.diff_transforms.next();
7706        }
7707
7708        let diff_transform_start = self.diff_transforms.start().0;
7709        let diff_transform_end = self.diff_transforms.end().0;
7710        debug_assert!(self.range.start < diff_transform_end);
7711
7712        let diff_transform = self.diff_transforms.item()?;
7713        match diff_transform {
7714            DiffTransform::BufferContent { .. } => {
7715                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7716                    chunk
7717                } else {
7718                    let chunk = self.next_excerpt_chunk().unwrap();
7719                    self.buffer_chunk.insert(chunk)
7720                };
7721
7722                let chunk_end = self.range.start + chunk.text.len();
7723                let diff_transform_end = diff_transform_end.min(self.range.end);
7724
7725                if diff_transform_end < chunk_end {
7726                    let split_idx = diff_transform_end - self.range.start;
7727                    let (before, after) = chunk.text.split_at(split_idx);
7728                    self.range.start = diff_transform_end;
7729                    let mask = (1 << split_idx) - 1;
7730                    let chars = chunk.chars & mask;
7731                    let tabs = chunk.tabs & mask;
7732
7733                    chunk.text = after;
7734                    chunk.chars = chunk.chars >> split_idx;
7735                    chunk.tabs = chunk.tabs >> split_idx;
7736
7737                    Some(Chunk {
7738                        text: before,
7739                        chars,
7740                        tabs,
7741                        ..chunk.clone()
7742                    })
7743                } else {
7744                    self.range.start = chunk_end;
7745                    self.buffer_chunk.take()
7746                }
7747            }
7748            DiffTransform::DeletedHunk {
7749                buffer_id,
7750                base_text_byte_range,
7751                has_trailing_newline,
7752                ..
7753            } => {
7754                let base_text_start =
7755                    base_text_byte_range.start + self.range.start - diff_transform_start;
7756                let base_text_end =
7757                    base_text_byte_range.start + self.range.end - diff_transform_start;
7758                let base_text_end = base_text_end.min(base_text_byte_range.end);
7759
7760                let mut chunks = if let Some((_, mut chunks)) = self
7761                    .diff_base_chunks
7762                    .take()
7763                    .filter(|(id, _)| id == buffer_id)
7764                {
7765                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7766                    {
7767                        chunks.seek(base_text_start..base_text_end);
7768                    }
7769                    chunks
7770                } else {
7771                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7772                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7773                };
7774
7775                let chunk = if let Some(chunk) = chunks.next() {
7776                    self.range.start += chunk.text.len();
7777                    self.diff_base_chunks = Some((*buffer_id, chunks));
7778                    chunk
7779                } else {
7780                    debug_assert!(has_trailing_newline);
7781                    self.range.start += "\n".len();
7782                    Chunk {
7783                        text: "\n",
7784                        chars: 1u128,
7785                        ..Default::default()
7786                    }
7787                };
7788                Some(chunk)
7789            }
7790        }
7791    }
7792}
7793
7794impl MultiBufferBytes<'_> {
7795    fn consume(&mut self, len: usize) {
7796        self.range.start += len;
7797        self.chunk = &self.chunk[len..];
7798
7799        if !self.range.is_empty() && self.chunk.is_empty() {
7800            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7801                self.chunk = chunk;
7802            } else if self.has_trailing_newline {
7803                self.has_trailing_newline = false;
7804                self.chunk = b"\n";
7805            } else {
7806                self.cursor.next();
7807                if let Some(region) = self.cursor.region() {
7808                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7809                        region.buffer_range.start
7810                            ..(region.buffer_range.start + self.range.end - region.range.start)
7811                                .min(region.buffer_range.end),
7812                    );
7813                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7814                    self.excerpt_bytes = Some(excerpt_bytes);
7815                    self.has_trailing_newline =
7816                        region.has_trailing_newline && self.range.end >= region.range.end;
7817                    if self.chunk.is_empty() && self.has_trailing_newline {
7818                        self.has_trailing_newline = false;
7819                        self.chunk = b"\n";
7820                    }
7821                }
7822            }
7823        }
7824    }
7825}
7826
7827impl<'a> Iterator for MultiBufferBytes<'a> {
7828    type Item = &'a [u8];
7829
7830    fn next(&mut self) -> Option<Self::Item> {
7831        let chunk = self.chunk;
7832        if chunk.is_empty() {
7833            None
7834        } else {
7835            self.consume(chunk.len());
7836            Some(chunk)
7837        }
7838    }
7839}
7840
7841impl io::Read for MultiBufferBytes<'_> {
7842    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7843        let len = cmp::min(buf.len(), self.chunk.len());
7844        buf[..len].copy_from_slice(&self.chunk[..len]);
7845        if len > 0 {
7846            self.consume(len);
7847        }
7848        Ok(len)
7849    }
7850}
7851
7852impl io::Read for ReversedMultiBufferBytes<'_> {
7853    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7854        let len = cmp::min(buf.len(), self.chunk.len());
7855        buf[..len].copy_from_slice(&self.chunk[..len]);
7856        buf[..len].reverse();
7857        if len > 0 {
7858            self.range.end -= len;
7859            self.chunk = &self.chunk[..self.chunk.len() - len];
7860            if !self.range.is_empty()
7861                && self.chunk.is_empty()
7862                && let Some(chunk) = self.chunks.next()
7863            {
7864                self.chunk = chunk.as_bytes();
7865            }
7866        }
7867        Ok(len)
7868    }
7869}
7870
7871impl<'a> Iterator for ExcerptChunks<'a> {
7872    type Item = Chunk<'a>;
7873
7874    fn next(&mut self) -> Option<Self::Item> {
7875        if let Some(chunk) = self.content_chunks.next() {
7876            return Some(chunk);
7877        }
7878
7879        if self.footer_height > 0 {
7880            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7881            let chars = (1 << self.footer_height) - 1;
7882            self.footer_height = 0;
7883            return Some(Chunk {
7884                text,
7885                chars,
7886                ..Default::default()
7887            });
7888        }
7889
7890        None
7891    }
7892}
7893
7894impl ToOffset for Point {
7895    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7896        snapshot.point_to_offset(*self)
7897    }
7898}
7899
7900impl ToOffset for usize {
7901    #[track_caller]
7902    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7903        assert!(
7904            *self <= snapshot.len(),
7905            "offset {} is greater than the snapshot.len() {}",
7906            *self,
7907            snapshot.len(),
7908        );
7909        *self
7910    }
7911}
7912
7913impl ToOffset for OffsetUtf16 {
7914    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7915        snapshot.offset_utf16_to_offset(*self)
7916    }
7917}
7918
7919impl ToOffset for PointUtf16 {
7920    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7921        snapshot.point_utf16_to_offset(*self)
7922    }
7923}
7924
7925impl ToOffsetUtf16 for OffsetUtf16 {
7926    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7927        *self
7928    }
7929}
7930
7931impl ToOffsetUtf16 for usize {
7932    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7933        snapshot.offset_to_offset_utf16(*self)
7934    }
7935}
7936
7937impl ToPoint for usize {
7938    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7939        snapshot.offset_to_point(*self)
7940    }
7941}
7942
7943impl ToPoint for Point {
7944    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7945        *self
7946    }
7947}
7948
7949impl ToPointUtf16 for usize {
7950    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7951        snapshot.offset_to_point_utf16(*self)
7952    }
7953}
7954
7955impl ToPointUtf16 for Point {
7956    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7957        snapshot.point_to_point_utf16(*self)
7958    }
7959}
7960
7961impl ToPointUtf16 for PointUtf16 {
7962    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7963        *self
7964    }
7965}
7966
7967impl From<ExcerptId> for EntityId {
7968    fn from(id: ExcerptId) -> Self {
7969        EntityId::from(id.0 as u64)
7970    }
7971}
7972
7973#[cfg(debug_assertions)]
7974pub mod debug {
7975    use super::*;
7976
7977    pub trait ToMultiBufferDebugRanges {
7978        fn to_multi_buffer_debug_ranges(&self, snapshot: &MultiBufferSnapshot)
7979        -> Vec<Range<usize>>;
7980    }
7981
7982    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
7983        fn to_multi_buffer_debug_ranges(
7984            &self,
7985            snapshot: &MultiBufferSnapshot,
7986        ) -> Vec<Range<usize>> {
7987            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
7988        }
7989    }
7990
7991    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
7992        fn to_multi_buffer_debug_ranges(
7993            &self,
7994            snapshot: &MultiBufferSnapshot,
7995        ) -> Vec<Range<usize>> {
7996            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
7997                .to_multi_buffer_debug_ranges(snapshot)
7998        }
7999    }
8000
8001    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
8002        fn to_multi_buffer_debug_ranges(
8003            &self,
8004            snapshot: &MultiBufferSnapshot,
8005        ) -> Vec<Range<usize>> {
8006            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8007        }
8008    }
8009
8010    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8011        fn to_multi_buffer_debug_ranges(
8012            &self,
8013            snapshot: &MultiBufferSnapshot,
8014        ) -> Vec<Range<usize>> {
8015            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8016        }
8017    }
8018
8019    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8020        fn to_multi_buffer_debug_ranges(
8021            &self,
8022            snapshot: &MultiBufferSnapshot,
8023        ) -> Vec<Range<usize>> {
8024            self.iter()
8025                .map(|item| {
8026                    let offset = item.to_offset(snapshot);
8027                    offset..offset
8028                })
8029                .collect()
8030        }
8031    }
8032
8033    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8034        fn to_multi_buffer_debug_ranges(
8035            &self,
8036            snapshot: &MultiBufferSnapshot,
8037        ) -> Vec<Range<usize>> {
8038            self.iter()
8039                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8040                .collect()
8041        }
8042    }
8043}