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, DiagnosticEntry, 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;
  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 MultiOrSingleBufferOffsetRange {
  84    Single(Range<usize>),
  85    Multi(Range<usize>),
  86}
  87
  88#[derive(Clone, Debug, PartialEq, Eq)]
  89pub enum Event {
  90    ExcerptsAdded {
  91        buffer: Entity<Buffer>,
  92        predecessor: ExcerptId,
  93        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  94    },
  95    ExcerptsRemoved {
  96        ids: Vec<ExcerptId>,
  97        removed_buffer_ids: Vec<BufferId>,
  98    },
  99    ExcerptsExpanded {
 100        ids: Vec<ExcerptId>,
 101    },
 102    ExcerptsEdited {
 103        excerpt_ids: Vec<ExcerptId>,
 104        buffer_ids: Vec<BufferId>,
 105    },
 106    DiffHunksToggled,
 107    Edited {
 108        singleton_buffer_edited: bool,
 109        edited_buffer: Option<Entity<Buffer>>,
 110    },
 111    TransactionUndone {
 112        transaction_id: TransactionId,
 113    },
 114    Reloaded,
 115    LanguageChanged(BufferId),
 116    Reparsed(BufferId),
 117    Saved,
 118    FileHandleChanged,
 119    DirtyChanged,
 120    DiagnosticsUpdated,
 121    BufferDiffChanged,
 122}
 123
 124/// A diff hunk, representing a range of consequent lines in a multibuffer.
 125#[derive(Debug, Clone, PartialEq, Eq)]
 126pub struct MultiBufferDiffHunk {
 127    /// The row range in the multibuffer where this diff hunk appears.
 128    pub row_range: Range<MultiBufferRow>,
 129    /// The buffer ID that this hunk belongs to.
 130    pub buffer_id: BufferId,
 131    /// The range of the underlying buffer that this hunk corresponds to.
 132    pub buffer_range: Range<text::Anchor>,
 133    /// The excerpt that contains the diff hunk.
 134    pub excerpt_id: ExcerptId,
 135    /// The range within the buffer's diff base that this hunk corresponds to.
 136    pub diff_base_byte_range: Range<usize>,
 137    /// Whether or not this hunk also appears in the 'secondary diff'.
 138    pub secondary_status: DiffHunkSecondaryStatus,
 139}
 140
 141impl MultiBufferDiffHunk {
 142    pub fn status(&self) -> DiffHunkStatus {
 143        let kind = if self.buffer_range.start == self.buffer_range.end {
 144            DiffHunkStatusKind::Deleted
 145        } else if self.diff_base_byte_range.is_empty() {
 146            DiffHunkStatusKind::Added
 147        } else {
 148            DiffHunkStatusKind::Modified
 149        };
 150        DiffHunkStatus {
 151            kind,
 152            secondary: self.secondary_status,
 153        }
 154    }
 155
 156    pub fn is_created_file(&self) -> bool {
 157        self.diff_base_byte_range == (0..0)
 158            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 159    }
 160
 161    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 162        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 163        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 164        start..end
 165    }
 166}
 167
 168#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 169pub struct PathKey {
 170    namespace: u32,
 171    path: Arc<str>,
 172}
 173
 174impl PathKey {
 175    pub fn namespaced(namespace: u32, path: Arc<str>) -> Self {
 176        Self { namespace, path }
 177    }
 178
 179    pub fn for_buffer(buffer: &Entity<Buffer>, cx: &App) -> Self {
 180        if let Some(file) = buffer.read(cx).file() {
 181            Self::namespaced(1, file.full_path(cx).to_string_lossy().into_owned().into())
 182        } else {
 183            Self::namespaced(0, buffer.entity_id().to_string().into())
 184        }
 185    }
 186
 187    pub fn path(&self) -> &Arc<str> {
 188        &self.path
 189    }
 190}
 191
 192pub type MultiBufferPoint = Point;
 193type ExcerptOffset = TypedOffset<Excerpt>;
 194type ExcerptPoint = TypedPoint<Excerpt>;
 195
 196#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 197#[serde(transparent)]
 198pub struct MultiBufferRow(pub u32);
 199
 200impl MultiBufferRow {
 201    pub const MIN: Self = Self(0);
 202    pub const MAX: Self = Self(u32::MAX);
 203}
 204
 205impl std::ops::Add<usize> for MultiBufferRow {
 206    type Output = Self;
 207
 208    fn add(self, rhs: usize) -> Self::Output {
 209        MultiBufferRow(self.0 + rhs as u32)
 210    }
 211}
 212
 213#[derive(Clone)]
 214struct History {
 215    next_transaction_id: TransactionId,
 216    undo_stack: Vec<Transaction>,
 217    redo_stack: Vec<Transaction>,
 218    transaction_depth: usize,
 219    group_interval: Duration,
 220}
 221
 222#[derive(Clone)]
 223struct Transaction {
 224    id: TransactionId,
 225    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 226    first_edit_at: Instant,
 227    last_edit_at: Instant,
 228    suppress_grouping: bool,
 229}
 230
 231pub trait ToOffset: 'static + fmt::Debug {
 232    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 233}
 234
 235pub trait ToOffsetUtf16: 'static + fmt::Debug {
 236    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 237}
 238
 239pub trait ToPoint: 'static + fmt::Debug {
 240    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 241}
 242
 243pub trait ToPointUtf16: 'static + fmt::Debug {
 244    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 245}
 246
 247struct BufferState {
 248    buffer: Entity<Buffer>,
 249    last_version: clock::Global,
 250    last_non_text_state_update_count: usize,
 251    excerpts: Vec<Locator>,
 252    _subscriptions: [gpui::Subscription; 2],
 253}
 254
 255struct DiffState {
 256    diff: Entity<BufferDiff>,
 257    _subscription: gpui::Subscription,
 258}
 259
 260impl DiffState {
 261    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 262        DiffState {
 263            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 264                BufferDiffEvent::DiffChanged { changed_range } => {
 265                    if let Some(changed_range) = changed_range.clone() {
 266                        this.buffer_diff_changed(diff, changed_range, cx)
 267                    }
 268                    cx.emit(Event::BufferDiffChanged);
 269                }
 270                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 271                _ => {}
 272            }),
 273            diff,
 274        }
 275    }
 276}
 277
 278/// The contents of a [`MultiBuffer`] at a single point in time.
 279#[derive(Clone, Default)]
 280pub struct MultiBufferSnapshot {
 281    singleton: bool,
 282    excerpts: SumTree<Excerpt>,
 283    excerpt_ids: SumTree<ExcerptIdMapping>,
 284    diffs: TreeMap<BufferId, BufferDiffSnapshot>,
 285    diff_transforms: SumTree<DiffTransform>,
 286    replaced_excerpts: TreeMap<ExcerptId, ExcerptId>,
 287    trailing_excerpt_update_count: usize,
 288    all_diff_hunks_expanded: bool,
 289    non_text_state_update_count: usize,
 290    edit_count: usize,
 291    is_dirty: bool,
 292    has_deleted_file: bool,
 293    has_conflict: bool,
 294    show_headers: bool,
 295}
 296
 297#[derive(Debug, Clone)]
 298enum DiffTransform {
 299    BufferContent {
 300        summary: TextSummary,
 301        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 302    },
 303    DeletedHunk {
 304        summary: TextSummary,
 305        buffer_id: BufferId,
 306        hunk_info: DiffTransformHunkInfo,
 307        base_text_byte_range: Range<usize>,
 308        has_trailing_newline: bool,
 309    },
 310}
 311
 312#[derive(Clone, Copy, Debug)]
 313struct DiffTransformHunkInfo {
 314    excerpt_id: ExcerptId,
 315    hunk_start_anchor: text::Anchor,
 316    hunk_secondary_status: DiffHunkSecondaryStatus,
 317}
 318
 319impl Eq for DiffTransformHunkInfo {}
 320
 321impl PartialEq for DiffTransformHunkInfo {
 322    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 323        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 324    }
 325}
 326
 327impl std::hash::Hash for DiffTransformHunkInfo {
 328    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 329        self.excerpt_id.hash(state);
 330        self.hunk_start_anchor.hash(state);
 331    }
 332}
 333
 334#[derive(Clone)]
 335pub struct ExcerptInfo {
 336    pub id: ExcerptId,
 337    pub buffer: BufferSnapshot,
 338    pub buffer_id: BufferId,
 339    pub range: ExcerptRange<text::Anchor>,
 340    pub end_row: MultiBufferRow,
 341}
 342
 343impl std::fmt::Debug for ExcerptInfo {
 344    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 345        f.debug_struct(type_name::<Self>())
 346            .field("id", &self.id)
 347            .field("buffer_id", &self.buffer_id)
 348            .field("path", &self.buffer.file().map(|f| f.path()))
 349            .field("range", &self.range)
 350            .finish()
 351    }
 352}
 353
 354/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 355#[derive(Debug)]
 356pub struct ExcerptBoundary {
 357    pub prev: Option<ExcerptInfo>,
 358    pub next: ExcerptInfo,
 359    /// The row in the `MultiBuffer` where the boundary is located
 360    pub row: MultiBufferRow,
 361}
 362
 363impl ExcerptBoundary {
 364    pub fn starts_new_buffer(&self) -> bool {
 365        match (self.prev.as_ref(), &self.next) {
 366            (None, _) => true,
 367            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 368        }
 369    }
 370}
 371
 372#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 373pub struct ExpandInfo {
 374    pub direction: ExpandExcerptDirection,
 375    pub excerpt_id: ExcerptId,
 376}
 377
 378#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 379pub struct RowInfo {
 380    pub buffer_id: Option<BufferId>,
 381    pub buffer_row: Option<u32>,
 382    pub multibuffer_row: Option<MultiBufferRow>,
 383    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 384    pub expand_info: Option<ExpandInfo>,
 385}
 386
 387/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 388#[derive(Clone)]
 389struct Excerpt {
 390    /// The unique identifier for this excerpt
 391    id: ExcerptId,
 392    /// The location of the excerpt in the [`MultiBuffer`]
 393    locator: Locator,
 394    /// The buffer being excerpted
 395    buffer_id: BufferId,
 396    /// A snapshot of the buffer being excerpted
 397    buffer: BufferSnapshot,
 398    /// The range of the buffer to be shown in the excerpt
 399    range: ExcerptRange<text::Anchor>,
 400    /// The last row in the excerpted slice of the buffer
 401    max_buffer_row: BufferRow,
 402    /// A summary of the text in the excerpt
 403    text_summary: TextSummary,
 404    has_trailing_newline: bool,
 405}
 406
 407/// A public view into an `Excerpt` in a [`MultiBuffer`].
 408///
 409/// Contains methods for getting the [`Buffer`] of the excerpt,
 410/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 411#[derive(Clone)]
 412pub struct MultiBufferExcerpt<'a> {
 413    excerpt: &'a Excerpt,
 414    diff_transforms: sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<usize>>,
 415    offset: usize,
 416    excerpt_offset: ExcerptDimension<usize>,
 417    buffer_offset: usize,
 418}
 419
 420#[derive(Clone, Debug)]
 421struct ExcerptIdMapping {
 422    id: ExcerptId,
 423    locator: Locator,
 424}
 425
 426/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 427/// These ranges are relative to the buffer itself
 428#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 429pub struct ExcerptRange<T> {
 430    /// The full range of text to be shown in the excerpt.
 431    pub context: Range<T>,
 432    /// The primary range of text to be highlighted in the excerpt.
 433    /// In a multi-buffer search, this would be the text that matched the search
 434    pub primary: Range<T>,
 435}
 436
 437impl<T: Clone> ExcerptRange<T> {
 438    pub fn new(context: Range<T>) -> Self {
 439        Self {
 440            context: context.clone(),
 441            primary: context,
 442        }
 443    }
 444}
 445
 446#[derive(Clone, Debug, Default)]
 447pub struct ExcerptSummary {
 448    excerpt_id: ExcerptId,
 449    /// The location of the last [`Excerpt`] being summarized
 450    excerpt_locator: Locator,
 451    widest_line_number: u32,
 452    text: TextSummary,
 453}
 454
 455#[derive(Debug, Clone)]
 456pub struct DiffTransformSummary {
 457    input: TextSummary,
 458    output: TextSummary,
 459}
 460
 461#[derive(Clone)]
 462pub struct MultiBufferRows<'a> {
 463    point: Point,
 464    is_empty: bool,
 465    is_singleton: bool,
 466    cursor: MultiBufferCursor<'a, Point>,
 467}
 468
 469pub struct MultiBufferChunks<'a> {
 470    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 471    diff_transforms: Cursor<'a, 'static, DiffTransform, Dimensions<usize, ExcerptOffset>>,
 472    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 473    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 474    buffer_chunk: Option<Chunk<'a>>,
 475    range: Range<usize>,
 476    excerpt_offset_range: Range<ExcerptOffset>,
 477    excerpt_chunks: Option<ExcerptChunks<'a>>,
 478    language_aware: bool,
 479}
 480
 481pub struct ReversedMultiBufferChunks<'a> {
 482    cursor: MultiBufferCursor<'a, usize>,
 483    current_chunks: Option<rope::Chunks<'a>>,
 484    start: usize,
 485    offset: usize,
 486}
 487
 488pub struct MultiBufferBytes<'a> {
 489    range: Range<usize>,
 490    cursor: MultiBufferCursor<'a, usize>,
 491    excerpt_bytes: Option<text::Bytes<'a>>,
 492    has_trailing_newline: bool,
 493    chunk: &'a [u8],
 494}
 495
 496pub struct ReversedMultiBufferBytes<'a> {
 497    range: Range<usize>,
 498    chunks: ReversedMultiBufferChunks<'a>,
 499    chunk: &'a [u8],
 500}
 501
 502#[derive(Clone)]
 503struct DiffTransforms<D> {
 504    output_dimension: OutputDimension<D>,
 505    excerpt_dimension: ExcerptDimension<D>,
 506}
 507
 508impl<'a, D: TextDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<D> {
 509    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
 510        Self {
 511            output_dimension: OutputDimension::zero(cx),
 512            excerpt_dimension: <ExcerptDimension<D> as Dimension<'a, DiffTransformSummary>>::zero(
 513                cx,
 514            ),
 515        }
 516    }
 517
 518    fn add_summary(
 519        &mut self,
 520        summary: &'a DiffTransformSummary,
 521        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
 522    ) {
 523        self.output_dimension.add_summary(summary, cx);
 524        self.excerpt_dimension.add_summary(summary, cx);
 525    }
 526}
 527
 528#[derive(Clone)]
 529struct MultiBufferCursor<'a, D: TextDimension> {
 530    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<D>>,
 531    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<D>>,
 532    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 533    cached_region: Option<MultiBufferRegion<'a, D>>,
 534}
 535
 536#[derive(Clone)]
 537struct MultiBufferRegion<'a, D: TextDimension> {
 538    buffer: &'a BufferSnapshot,
 539    is_main_buffer: bool,
 540    diff_hunk_status: Option<DiffHunkStatus>,
 541    excerpt: &'a Excerpt,
 542    buffer_range: Range<D>,
 543    range: Range<D>,
 544    has_trailing_newline: bool,
 545}
 546
 547struct ExcerptChunks<'a> {
 548    excerpt_id: ExcerptId,
 549    content_chunks: BufferChunks<'a>,
 550    footer_height: usize,
 551}
 552
 553#[derive(Debug)]
 554struct BufferEdit {
 555    range: Range<usize>,
 556    new_text: Arc<str>,
 557    is_insertion: bool,
 558    original_indent_column: Option<u32>,
 559    excerpt_id: ExcerptId,
 560}
 561
 562#[derive(Clone, Copy, Debug, PartialEq)]
 563enum DiffChangeKind {
 564    BufferEdited,
 565    DiffUpdated { base_changed: bool },
 566    ExpandOrCollapseHunks { expand: bool },
 567}
 568
 569#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 570pub enum ExpandExcerptDirection {
 571    Up,
 572    Down,
 573    UpAndDown,
 574}
 575
 576impl ExpandExcerptDirection {
 577    pub fn should_expand_up(&self) -> bool {
 578        match self {
 579            ExpandExcerptDirection::Up => true,
 580            ExpandExcerptDirection::Down => false,
 581            ExpandExcerptDirection::UpAndDown => true,
 582        }
 583    }
 584
 585    pub fn should_expand_down(&self) -> bool {
 586        match self {
 587            ExpandExcerptDirection::Up => false,
 588            ExpandExcerptDirection::Down => true,
 589            ExpandExcerptDirection::UpAndDown => true,
 590        }
 591    }
 592}
 593
 594#[derive(Clone, Debug, PartialEq)]
 595pub struct IndentGuide {
 596    pub buffer_id: BufferId,
 597    pub start_row: MultiBufferRow,
 598    pub end_row: MultiBufferRow,
 599    pub depth: u32,
 600    pub tab_size: u32,
 601    pub settings: IndentGuideSettings,
 602}
 603
 604impl IndentGuide {
 605    pub fn indent_level(&self) -> u32 {
 606        self.depth * self.tab_size
 607    }
 608}
 609
 610impl MultiBuffer {
 611    pub fn new(capability: Capability) -> Self {
 612        Self {
 613            snapshot: RefCell::new(MultiBufferSnapshot {
 614                show_headers: true,
 615                ..MultiBufferSnapshot::default()
 616            }),
 617            buffers: RefCell::default(),
 618            diffs: HashMap::default(),
 619            subscriptions: Topic::default(),
 620            singleton: false,
 621            capability,
 622            title: None,
 623            excerpts_by_path: Default::default(),
 624            paths_by_excerpt: Default::default(),
 625            buffer_changed_since_sync: Default::default(),
 626            history: History {
 627                next_transaction_id: clock::Lamport::default(),
 628                undo_stack: Vec::new(),
 629                redo_stack: Vec::new(),
 630                transaction_depth: 0,
 631                group_interval: Duration::from_millis(300),
 632            },
 633        }
 634    }
 635
 636    pub fn without_headers(capability: Capability) -> Self {
 637        Self {
 638            snapshot: Default::default(),
 639            buffers: Default::default(),
 640            excerpts_by_path: Default::default(),
 641            paths_by_excerpt: Default::default(),
 642            diffs: HashMap::default(),
 643            subscriptions: Default::default(),
 644            singleton: false,
 645            capability,
 646            buffer_changed_since_sync: Default::default(),
 647            history: History {
 648                next_transaction_id: Default::default(),
 649                undo_stack: Default::default(),
 650                redo_stack: Default::default(),
 651                transaction_depth: 0,
 652                group_interval: Duration::from_millis(300),
 653            },
 654            title: Default::default(),
 655        }
 656    }
 657
 658    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
 659        let mut buffers = HashMap::default();
 660        let buffer_changed_since_sync = Rc::new(Cell::new(false));
 661        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 662            buffer_state.buffer.update(new_cx, |buffer, _| {
 663                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
 664            });
 665            buffers.insert(
 666                *buffer_id,
 667                BufferState {
 668                    buffer: buffer_state.buffer.clone(),
 669                    last_version: buffer_state.last_version.clone(),
 670                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 671                    excerpts: buffer_state.excerpts.clone(),
 672                    _subscriptions: [
 673                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 674                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 675                    ],
 676                },
 677            );
 678        }
 679        let mut diff_bases = HashMap::default();
 680        for (buffer_id, diff) in self.diffs.iter() {
 681            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
 682        }
 683        Self {
 684            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 685            buffers: RefCell::new(buffers),
 686            excerpts_by_path: Default::default(),
 687            paths_by_excerpt: Default::default(),
 688            diffs: diff_bases,
 689            subscriptions: Default::default(),
 690            singleton: self.singleton,
 691            capability: self.capability,
 692            history: self.history.clone(),
 693            title: self.title.clone(),
 694            buffer_changed_since_sync,
 695        }
 696    }
 697
 698    pub fn with_title(mut self, title: String) -> Self {
 699        self.title = Some(title);
 700        self
 701    }
 702
 703    pub fn read_only(&self) -> bool {
 704        self.capability == Capability::ReadOnly
 705    }
 706
 707    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
 708        let mut this = Self::new(buffer.read(cx).capability());
 709        this.singleton = true;
 710        this.push_excerpts(
 711            buffer,
 712            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
 713            cx,
 714        );
 715        this.snapshot.borrow_mut().singleton = true;
 716        this
 717    }
 718
 719    /// Returns an up-to-date snapshot of the MultiBuffer.
 720    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
 721        self.sync(cx);
 722        self.snapshot.borrow().clone()
 723    }
 724
 725    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
 726        self.sync(cx);
 727        self.snapshot.borrow()
 728    }
 729
 730    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
 731        if self.singleton {
 732            Some(
 733                self.buffers
 734                    .borrow()
 735                    .values()
 736                    .next()
 737                    .unwrap()
 738                    .buffer
 739                    .clone(),
 740            )
 741        } else {
 742            None
 743        }
 744    }
 745
 746    pub fn is_singleton(&self) -> bool {
 747        self.singleton
 748    }
 749
 750    pub fn subscribe(&mut self) -> Subscription {
 751        self.subscriptions.subscribe()
 752    }
 753
 754    pub fn is_dirty(&self, cx: &App) -> bool {
 755        self.read(cx).is_dirty()
 756    }
 757
 758    pub fn has_deleted_file(&self, cx: &App) -> bool {
 759        self.read(cx).has_deleted_file()
 760    }
 761
 762    pub fn has_conflict(&self, cx: &App) -> bool {
 763        self.read(cx).has_conflict()
 764    }
 765
 766    // The `is_empty` signature doesn't match what clippy expects
 767    #[allow(clippy::len_without_is_empty)]
 768    pub fn len(&self, cx: &App) -> usize {
 769        self.read(cx).len()
 770    }
 771
 772    pub fn is_empty(&self) -> bool {
 773        self.buffers.borrow().is_empty()
 774    }
 775
 776    pub fn symbols_containing<T: ToOffset>(
 777        &self,
 778        offset: T,
 779        theme: Option<&SyntaxTheme>,
 780        cx: &App,
 781    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 782        self.read(cx).symbols_containing(offset, theme)
 783    }
 784
 785    pub fn edit<I, S, T>(
 786        &self,
 787        edits: I,
 788        autoindent_mode: Option<AutoindentMode>,
 789        cx: &mut Context<Self>,
 790    ) where
 791        I: IntoIterator<Item = (Range<S>, T)>,
 792        S: ToOffset,
 793        T: Into<Arc<str>>,
 794    {
 795        let snapshot = self.read(cx);
 796        let edits = edits
 797            .into_iter()
 798            .map(|(range, new_text)| {
 799                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 800                if range.start > range.end {
 801                    mem::swap(&mut range.start, &mut range.end);
 802                }
 803                (range, new_text.into())
 804            })
 805            .collect::<Vec<_>>();
 806
 807        return edit_internal(self, snapshot, edits, autoindent_mode, cx);
 808
 809        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 810        fn edit_internal(
 811            this: &MultiBuffer,
 812            snapshot: Ref<MultiBufferSnapshot>,
 813            edits: Vec<(Range<usize>, Arc<str>)>,
 814            mut autoindent_mode: Option<AutoindentMode>,
 815            cx: &mut Context<MultiBuffer>,
 816        ) {
 817            if this.read_only() || this.buffers.borrow().is_empty() {
 818                return;
 819            }
 820
 821            let original_indent_columns = match &mut autoindent_mode {
 822                Some(AutoindentMode::Block {
 823                    original_indent_columns,
 824                }) => mem::take(original_indent_columns),
 825                _ => Default::default(),
 826            };
 827
 828            let (buffer_edits, edited_excerpt_ids) =
 829                this.convert_edits_to_buffer_edits(edits, &snapshot, &original_indent_columns);
 830            drop(snapshot);
 831
 832            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
 833            for (buffer_id, mut edits) in buffer_edits {
 834                buffer_ids.push(buffer_id);
 835                edits.sort_by_key(|edit| edit.range.start);
 836                this.buffers.borrow()[&buffer_id]
 837                    .buffer
 838                    .update(cx, |buffer, cx| {
 839                        let mut edits = edits.into_iter().peekable();
 840                        let mut insertions = Vec::new();
 841                        let mut original_indent_columns = Vec::new();
 842                        let mut deletions = Vec::new();
 843                        let empty_str: Arc<str> = Arc::default();
 844                        while let Some(BufferEdit {
 845                            mut range,
 846                            mut new_text,
 847                            mut is_insertion,
 848                            original_indent_column,
 849                            excerpt_id,
 850                        }) = edits.next()
 851                        {
 852                            while let Some(BufferEdit {
 853                                range: next_range,
 854                                is_insertion: next_is_insertion,
 855                                new_text: next_new_text,
 856                                excerpt_id: next_excerpt_id,
 857                                ..
 858                            }) = edits.peek()
 859                            {
 860                                if range.end >= next_range.start {
 861                                    range.end = cmp::max(next_range.end, range.end);
 862                                    is_insertion |= *next_is_insertion;
 863                                    if excerpt_id == *next_excerpt_id {
 864                                        new_text = format!("{new_text}{next_new_text}").into();
 865                                    }
 866                                    edits.next();
 867                                } else {
 868                                    break;
 869                                }
 870                            }
 871
 872                            if is_insertion {
 873                                original_indent_columns.push(original_indent_column);
 874                                insertions.push((
 875                                    buffer.anchor_before(range.start)
 876                                        ..buffer.anchor_before(range.end),
 877                                    new_text.clone(),
 878                                ));
 879                            } else if !range.is_empty() {
 880                                deletions.push((
 881                                    buffer.anchor_before(range.start)
 882                                        ..buffer.anchor_before(range.end),
 883                                    empty_str.clone(),
 884                                ));
 885                            }
 886                        }
 887
 888                        let deletion_autoindent_mode =
 889                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 890                                Some(AutoindentMode::Block {
 891                                    original_indent_columns: Default::default(),
 892                                })
 893                            } else {
 894                                autoindent_mode.clone()
 895                            };
 896                        let insertion_autoindent_mode =
 897                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 898                                Some(AutoindentMode::Block {
 899                                    original_indent_columns,
 900                                })
 901                            } else {
 902                                autoindent_mode.clone()
 903                            };
 904
 905                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 906                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 907                    })
 908            }
 909
 910            cx.emit(Event::ExcerptsEdited {
 911                excerpt_ids: edited_excerpt_ids,
 912                buffer_ids,
 913            });
 914        }
 915    }
 916
 917    fn convert_edits_to_buffer_edits(
 918        &self,
 919        edits: Vec<(Range<usize>, Arc<str>)>,
 920        snapshot: &MultiBufferSnapshot,
 921        original_indent_columns: &[Option<u32>],
 922    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
 923        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 924        let mut edited_excerpt_ids = Vec::new();
 925        let mut cursor = snapshot.cursor::<usize>();
 926        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
 927            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
 928
 929            cursor.seek(&range.start);
 930            let mut start_region = cursor.region().expect("start offset out of bounds");
 931            if !start_region.is_main_buffer {
 932                cursor.next();
 933                if let Some(region) = cursor.region() {
 934                    start_region = region;
 935                } else {
 936                    continue;
 937                }
 938            }
 939
 940            if range.end < start_region.range.start {
 941                continue;
 942            }
 943
 944            if range.end > start_region.range.end {
 945                cursor.seek_forward(&range.end);
 946            }
 947            let mut end_region = cursor.region().expect("end offset out of bounds");
 948            if !end_region.is_main_buffer {
 949                cursor.prev();
 950                if let Some(region) = cursor.region() {
 951                    end_region = region;
 952                } else {
 953                    continue;
 954                }
 955            }
 956
 957            if range.start > end_region.range.end {
 958                continue;
 959            }
 960
 961            let start_overshoot = range.start.saturating_sub(start_region.range.start);
 962            let end_overshoot = range.end.saturating_sub(end_region.range.start);
 963            let buffer_start = (start_region.buffer_range.start + start_overshoot)
 964                .min(start_region.buffer_range.end);
 965            let buffer_end =
 966                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
 967
 968            if start_region.excerpt.id == end_region.excerpt.id {
 969                if start_region.is_main_buffer {
 970                    edited_excerpt_ids.push(start_region.excerpt.id);
 971                    buffer_edits
 972                        .entry(start_region.buffer.remote_id())
 973                        .or_default()
 974                        .push(BufferEdit {
 975                            range: buffer_start..buffer_end,
 976                            new_text,
 977                            is_insertion: true,
 978                            original_indent_column,
 979                            excerpt_id: start_region.excerpt.id,
 980                        });
 981                }
 982            } else {
 983                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
 984                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
 985                if start_region.is_main_buffer {
 986                    edited_excerpt_ids.push(start_region.excerpt.id);
 987                    buffer_edits
 988                        .entry(start_region.buffer.remote_id())
 989                        .or_default()
 990                        .push(BufferEdit {
 991                            range: start_excerpt_range,
 992                            new_text: new_text.clone(),
 993                            is_insertion: true,
 994                            original_indent_column,
 995                            excerpt_id: start_region.excerpt.id,
 996                        });
 997                }
 998                if end_region.is_main_buffer {
 999                    edited_excerpt_ids.push(end_region.excerpt.id);
1000                    buffer_edits
1001                        .entry(end_region.buffer.remote_id())
1002                        .or_default()
1003                        .push(BufferEdit {
1004                            range: end_excerpt_range,
1005                            new_text: new_text.clone(),
1006                            is_insertion: false,
1007                            original_indent_column,
1008                            excerpt_id: end_region.excerpt.id,
1009                        });
1010                }
1011
1012                cursor.seek(&range.start);
1013                cursor.next_excerpt();
1014                while let Some(region) = cursor.region() {
1015                    if region.excerpt.id == end_region.excerpt.id {
1016                        break;
1017                    }
1018                    if region.is_main_buffer {
1019                        edited_excerpt_ids.push(region.excerpt.id);
1020                        buffer_edits
1021                            .entry(region.buffer.remote_id())
1022                            .or_default()
1023                            .push(BufferEdit {
1024                                range: region.buffer_range,
1025                                new_text: new_text.clone(),
1026                                is_insertion: false,
1027                                original_indent_column,
1028                                excerpt_id: region.excerpt.id,
1029                            });
1030                    }
1031                    cursor.next_excerpt();
1032                }
1033            }
1034        }
1035        (buffer_edits, edited_excerpt_ids)
1036    }
1037
1038    pub fn autoindent_ranges<I, S>(&self, ranges: I, cx: &mut Context<Self>)
1039    where
1040        I: IntoIterator<Item = Range<S>>,
1041        S: ToOffset,
1042    {
1043        let snapshot = self.read(cx);
1044        let empty = Arc::<str>::from("");
1045        let edits = ranges
1046            .into_iter()
1047            .map(|range| {
1048                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
1049                if range.start > range.end {
1050                    mem::swap(&mut range.start, &mut range.end);
1051                }
1052                (range, empty.clone())
1053            })
1054            .collect::<Vec<_>>();
1055
1056        return autoindent_ranges_internal(self, snapshot, edits, cx);
1057
1058        fn autoindent_ranges_internal(
1059            this: &MultiBuffer,
1060            snapshot: Ref<MultiBufferSnapshot>,
1061            edits: Vec<(Range<usize>, Arc<str>)>,
1062            cx: &mut Context<MultiBuffer>,
1063        ) {
1064            if this.read_only() || this.buffers.borrow().is_empty() {
1065                return;
1066            }
1067
1068            let (buffer_edits, edited_excerpt_ids) =
1069                this.convert_edits_to_buffer_edits(edits, &snapshot, &[]);
1070            drop(snapshot);
1071
1072            let mut buffer_ids = Vec::new();
1073            for (buffer_id, mut edits) in buffer_edits {
1074                buffer_ids.push(buffer_id);
1075                edits.sort_unstable_by_key(|edit| edit.range.start);
1076
1077                let mut ranges: Vec<Range<usize>> = Vec::new();
1078                for edit in edits {
1079                    if let Some(last_range) = ranges.last_mut()
1080                        && edit.range.start <= last_range.end
1081                    {
1082                        last_range.end = last_range.end.max(edit.range.end);
1083                        continue;
1084                    }
1085                    ranges.push(edit.range);
1086                }
1087
1088                this.buffers.borrow()[&buffer_id]
1089                    .buffer
1090                    .update(cx, |buffer, cx| {
1091                        buffer.autoindent_ranges(ranges, cx);
1092                    })
1093            }
1094
1095            cx.emit(Event::ExcerptsEdited {
1096                excerpt_ids: edited_excerpt_ids,
1097                buffer_ids,
1098            });
1099        }
1100    }
1101
1102    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
1103    // You can also request the insertion of empty lines above and below the line starting at the returned point.
1104    // Panics if the given position is invalid.
1105    pub fn insert_empty_line(
1106        &mut self,
1107        position: impl ToPoint,
1108        space_above: bool,
1109        space_below: bool,
1110        cx: &mut Context<Self>,
1111    ) -> Point {
1112        let multibuffer_point = position.to_point(&self.read(cx));
1113        let (buffer, buffer_point, _) = self.point_to_buffer_point(multibuffer_point, cx).unwrap();
1114        self.start_transaction(cx);
1115        let empty_line_start = buffer.update(cx, |buffer, cx| {
1116            buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
1117        });
1118        self.end_transaction(cx);
1119        multibuffer_point + (empty_line_start - buffer_point)
1120    }
1121
1122    pub fn start_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1123        self.start_transaction_at(Instant::now(), cx)
1124    }
1125
1126    pub fn start_transaction_at(
1127        &mut self,
1128        now: Instant,
1129        cx: &mut Context<Self>,
1130    ) -> Option<TransactionId> {
1131        if let Some(buffer) = self.as_singleton() {
1132            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1133        }
1134
1135        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1136            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1137        }
1138        self.history.start_transaction(now)
1139    }
1140
1141    pub fn last_transaction_id(&self, cx: &App) -> Option<TransactionId> {
1142        if let Some(buffer) = self.as_singleton() {
1143            buffer
1144                .read(cx)
1145                .peek_undo_stack()
1146                .map(|history_entry| history_entry.transaction_id())
1147        } else {
1148            let last_transaction = self.history.undo_stack.last()?;
1149            Some(last_transaction.id)
1150        }
1151    }
1152
1153    pub fn end_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1154        self.end_transaction_at(Instant::now(), cx)
1155    }
1156
1157    pub fn end_transaction_at(
1158        &mut self,
1159        now: Instant,
1160        cx: &mut Context<Self>,
1161    ) -> Option<TransactionId> {
1162        if let Some(buffer) = self.as_singleton() {
1163            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
1164        }
1165
1166        let mut buffer_transactions = HashMap::default();
1167        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1168            if let Some(transaction_id) =
1169                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
1170            {
1171                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
1172            }
1173        }
1174
1175        if self.history.end_transaction(now, buffer_transactions) {
1176            let transaction_id = self.history.group().unwrap();
1177            Some(transaction_id)
1178        } else {
1179            None
1180        }
1181    }
1182
1183    pub fn edited_ranges_for_transaction<D>(
1184        &self,
1185        transaction_id: TransactionId,
1186        cx: &App,
1187    ) -> Vec<Range<D>>
1188    where
1189        D: TextDimension + Ord + Sub<D, Output = D>,
1190    {
1191        let Some(transaction) = self.history.transaction(transaction_id) else {
1192            return Vec::new();
1193        };
1194
1195        let mut ranges = Vec::new();
1196        let snapshot = self.read(cx);
1197        let buffers = self.buffers.borrow();
1198        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(());
1199
1200        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
1201            let Some(buffer_state) = buffers.get(buffer_id) else {
1202                continue;
1203            };
1204
1205            let buffer = buffer_state.buffer.read(cx);
1206            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
1207                for excerpt_id in &buffer_state.excerpts {
1208                    cursor.seek(excerpt_id, Bias::Left);
1209                    if let Some(excerpt) = cursor.item()
1210                        && excerpt.locator == *excerpt_id
1211                    {
1212                        let excerpt_buffer_start = excerpt.range.context.start.summary::<D>(buffer);
1213                        let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
1214                        let excerpt_range = excerpt_buffer_start..excerpt_buffer_end;
1215                        if excerpt_range.contains(&range.start)
1216                            && excerpt_range.contains(&range.end)
1217                        {
1218                            let excerpt_start = D::from_text_summary(&cursor.start().text);
1219
1220                            let mut start = excerpt_start;
1221                            start.add_assign(&(range.start - excerpt_buffer_start));
1222                            let mut end = excerpt_start;
1223                            end.add_assign(&(range.end - excerpt_buffer_start));
1224
1225                            ranges.push(start..end);
1226                            break;
1227                        }
1228                    }
1229                }
1230            }
1231        }
1232
1233        ranges.sort_by_key(|range| range.start);
1234        ranges
1235    }
1236
1237    pub fn merge_transactions(
1238        &mut self,
1239        transaction: TransactionId,
1240        destination: TransactionId,
1241        cx: &mut Context<Self>,
1242    ) {
1243        if let Some(buffer) = self.as_singleton() {
1244            buffer.update(cx, |buffer, _| {
1245                buffer.merge_transactions(transaction, destination)
1246            });
1247        } else if let Some(transaction) = self.history.forget(transaction)
1248            && let Some(destination) = self.history.transaction_mut(destination)
1249        {
1250            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1251                if let Some(destination_buffer_transaction_id) =
1252                    destination.buffer_transactions.get(&buffer_id)
1253                {
1254                    if let Some(state) = self.buffers.borrow().get(&buffer_id) {
1255                        state.buffer.update(cx, |buffer, _| {
1256                            buffer.merge_transactions(
1257                                buffer_transaction_id,
1258                                *destination_buffer_transaction_id,
1259                            )
1260                        });
1261                    }
1262                } else {
1263                    destination
1264                        .buffer_transactions
1265                        .insert(buffer_id, buffer_transaction_id);
1266                }
1267            }
1268        }
1269    }
1270
1271    pub fn finalize_last_transaction(&mut self, cx: &mut Context<Self>) {
1272        self.history.finalize_last_transaction();
1273        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1274            buffer.update(cx, |buffer, _| {
1275                buffer.finalize_last_transaction();
1276            });
1277        }
1278    }
1279
1280    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &Context<Self>)
1281    where
1282        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
1283    {
1284        self.history
1285            .push_transaction(buffer_transactions, Instant::now(), cx);
1286        self.history.finalize_last_transaction();
1287    }
1288
1289    pub fn group_until_transaction(
1290        &mut self,
1291        transaction_id: TransactionId,
1292        cx: &mut Context<Self>,
1293    ) {
1294        if let Some(buffer) = self.as_singleton() {
1295            buffer.update(cx, |buffer, _| {
1296                buffer.group_until_transaction(transaction_id)
1297            });
1298        } else {
1299            self.history.group_until(transaction_id);
1300        }
1301    }
1302
1303    pub fn set_active_selections(
1304        &self,
1305        selections: &[Selection<Anchor>],
1306        line_mode: bool,
1307        cursor_shape: CursorShape,
1308        cx: &mut Context<Self>,
1309    ) {
1310        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1311            Default::default();
1312        let snapshot = self.read(cx);
1313        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1314        for selection in selections {
1315            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1316            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1317
1318            cursor.seek(&Some(start_locator), Bias::Left);
1319            while let Some(excerpt) = cursor.item() {
1320                if excerpt.locator > *end_locator {
1321                    break;
1322                }
1323
1324                let mut start = excerpt.range.context.start;
1325                let mut end = excerpt.range.context.end;
1326                if excerpt.id == selection.start.excerpt_id {
1327                    start = selection.start.text_anchor;
1328                }
1329                if excerpt.id == selection.end.excerpt_id {
1330                    end = selection.end.text_anchor;
1331                }
1332                selections_by_buffer
1333                    .entry(excerpt.buffer_id)
1334                    .or_default()
1335                    .push(Selection {
1336                        id: selection.id,
1337                        start,
1338                        end,
1339                        reversed: selection.reversed,
1340                        goal: selection.goal,
1341                    });
1342
1343                cursor.next();
1344            }
1345        }
1346
1347        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1348            if !selections_by_buffer.contains_key(buffer_id) {
1349                buffer_state
1350                    .buffer
1351                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1352            }
1353        }
1354
1355        for (buffer_id, mut selections) in selections_by_buffer {
1356            self.buffers.borrow()[&buffer_id]
1357                .buffer
1358                .update(cx, |buffer, cx| {
1359                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1360                    let mut selections = selections.into_iter().peekable();
1361                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1362                        let mut selection = selections.next()?;
1363                        while let Some(next_selection) = selections.peek() {
1364                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1365                                let next_selection = selections.next().unwrap();
1366                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1367                                    selection.end = next_selection.end;
1368                                }
1369                            } else {
1370                                break;
1371                            }
1372                        }
1373                        Some(selection)
1374                    }));
1375                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1376                });
1377        }
1378    }
1379
1380    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1381        for buffer in self.buffers.borrow().values() {
1382            buffer
1383                .buffer
1384                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1385        }
1386    }
1387
1388    pub fn undo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1389        let mut transaction_id = None;
1390        if let Some(buffer) = self.as_singleton() {
1391            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1392        } else {
1393            while let Some(transaction) = self.history.pop_undo() {
1394                let mut undone = false;
1395                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1396                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1397                        undone |= buffer.update(cx, |buffer, cx| {
1398                            let undo_to = *buffer_transaction_id;
1399                            if let Some(entry) = buffer.peek_undo_stack() {
1400                                *buffer_transaction_id = entry.transaction_id();
1401                            }
1402                            buffer.undo_to_transaction(undo_to, cx)
1403                        });
1404                    }
1405                }
1406
1407                if undone {
1408                    transaction_id = Some(transaction.id);
1409                    break;
1410                }
1411            }
1412        }
1413
1414        if let Some(transaction_id) = transaction_id {
1415            cx.emit(Event::TransactionUndone { transaction_id });
1416        }
1417
1418        transaction_id
1419    }
1420
1421    pub fn redo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1422        if let Some(buffer) = self.as_singleton() {
1423            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1424        }
1425
1426        while let Some(transaction) = self.history.pop_redo() {
1427            let mut redone = false;
1428            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1429                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1430                    redone |= buffer.update(cx, |buffer, cx| {
1431                        let redo_to = *buffer_transaction_id;
1432                        if let Some(entry) = buffer.peek_redo_stack() {
1433                            *buffer_transaction_id = entry.transaction_id();
1434                        }
1435                        buffer.redo_to_transaction(redo_to, cx)
1436                    });
1437                }
1438            }
1439
1440            if redone {
1441                return Some(transaction.id);
1442            }
1443        }
1444
1445        None
1446    }
1447
1448    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1449        if let Some(buffer) = self.as_singleton() {
1450            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1451        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1452            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1453                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1454                    buffer.update(cx, |buffer, cx| {
1455                        buffer.undo_transaction(*transaction_id, cx)
1456                    });
1457                }
1458            }
1459        }
1460    }
1461
1462    pub fn forget_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1463        if let Some(buffer) = self.as_singleton() {
1464            buffer.update(cx, |buffer, _| {
1465                buffer.forget_transaction(transaction_id);
1466            });
1467        } else if let Some(transaction) = self.history.forget(transaction_id) {
1468            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1469                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1470                    state.buffer.update(cx, |buffer, _| {
1471                        buffer.forget_transaction(buffer_transaction_id);
1472                    });
1473                }
1474            }
1475        }
1476    }
1477
1478    pub fn push_excerpts<O>(
1479        &mut self,
1480        buffer: Entity<Buffer>,
1481        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1482        cx: &mut Context<Self>,
1483    ) -> Vec<ExcerptId>
1484    where
1485        O: text::ToOffset,
1486    {
1487        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1488    }
1489
1490    pub fn location_for_path(&self, path: &PathKey, cx: &App) -> Option<Anchor> {
1491        let excerpt_id = self.excerpts_by_path.get(path)?.first()?;
1492        let snapshot = self.snapshot(cx);
1493        let excerpt = snapshot.excerpt(*excerpt_id)?;
1494        Some(Anchor::in_buffer(
1495            *excerpt_id,
1496            excerpt.buffer_id,
1497            excerpt.range.context.start,
1498        ))
1499    }
1500
1501    pub fn excerpt_paths(&self) -> impl Iterator<Item = &PathKey> {
1502        self.excerpts_by_path.keys()
1503    }
1504
1505    fn expand_excerpts_with_paths(
1506        &mut self,
1507        ids: impl IntoIterator<Item = ExcerptId>,
1508        line_count: u32,
1509        direction: ExpandExcerptDirection,
1510        cx: &mut Context<Self>,
1511    ) {
1512        let grouped = ids
1513            .into_iter()
1514            .chunk_by(|id| self.paths_by_excerpt.get(id).cloned())
1515            .into_iter()
1516            .flat_map(|(k, v)| Some((k?, v.into_iter().collect::<Vec<_>>())))
1517            .collect::<Vec<_>>();
1518        let snapshot = self.snapshot(cx);
1519
1520        for (path, ids) in grouped.into_iter() {
1521            let Some(excerpt_ids) = self.excerpts_by_path.get(&path) else {
1522                continue;
1523            };
1524
1525            let ids_to_expand = HashSet::from_iter(ids);
1526            let expanded_ranges = excerpt_ids.iter().filter_map(|excerpt_id| {
1527                let excerpt = snapshot.excerpt(*excerpt_id)?;
1528
1529                let mut context = excerpt.range.context.to_point(&excerpt.buffer);
1530                if ids_to_expand.contains(excerpt_id) {
1531                    match direction {
1532                        ExpandExcerptDirection::Up => {
1533                            context.start.row = context.start.row.saturating_sub(line_count);
1534                            context.start.column = 0;
1535                        }
1536                        ExpandExcerptDirection::Down => {
1537                            context.end.row =
1538                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1539                            context.end.column = excerpt.buffer.line_len(context.end.row);
1540                        }
1541                        ExpandExcerptDirection::UpAndDown => {
1542                            context.start.row = context.start.row.saturating_sub(line_count);
1543                            context.start.column = 0;
1544                            context.end.row =
1545                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1546                            context.end.column = excerpt.buffer.line_len(context.end.row);
1547                        }
1548                    }
1549                }
1550
1551                Some(ExcerptRange {
1552                    context,
1553                    primary: excerpt.range.primary.to_point(&excerpt.buffer),
1554                })
1555            });
1556            let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1557            for range in expanded_ranges {
1558                if let Some(last_range) = merged_ranges.last_mut()
1559                    && last_range.context.end >= range.context.start
1560                {
1561                    last_range.context.end = range.context.end;
1562                    continue;
1563                }
1564                merged_ranges.push(range)
1565            }
1566            let Some(excerpt_id) = excerpt_ids.first() else {
1567                continue;
1568            };
1569            let Some(buffer_id) = &snapshot.buffer_id_for_excerpt(*excerpt_id) else {
1570                continue;
1571            };
1572
1573            let Some(buffer) = self
1574                .buffers
1575                .borrow()
1576                .get(buffer_id)
1577                .map(|b| b.buffer.clone())
1578            else {
1579                continue;
1580            };
1581
1582            let buffer_snapshot = buffer.read(cx).snapshot();
1583            self.update_path_excerpts(path.clone(), buffer, &buffer_snapshot, merged_ranges, cx);
1584        }
1585    }
1586
1587    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1588    pub fn set_excerpts_for_path(
1589        &mut self,
1590        path: PathKey,
1591        buffer: Entity<Buffer>,
1592        ranges: impl IntoIterator<Item = Range<Point>>,
1593        context_line_count: u32,
1594        cx: &mut Context<Self>,
1595    ) -> (Vec<Range<Anchor>>, bool) {
1596        let buffer_snapshot = buffer.read(cx).snapshot();
1597        let excerpt_ranges = build_excerpt_ranges(ranges, context_line_count, &buffer_snapshot);
1598
1599        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1600        self.set_merged_excerpt_ranges_for_path(
1601            path,
1602            buffer,
1603            excerpt_ranges,
1604            &buffer_snapshot,
1605            new,
1606            counts,
1607            cx,
1608        )
1609    }
1610
1611    pub fn set_excerpt_ranges_for_path(
1612        &mut self,
1613        path: PathKey,
1614        buffer: Entity<Buffer>,
1615        buffer_snapshot: &BufferSnapshot,
1616        excerpt_ranges: Vec<ExcerptRange<Point>>,
1617        cx: &mut Context<Self>,
1618    ) -> (Vec<Range<Anchor>>, bool) {
1619        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1620        self.set_merged_excerpt_ranges_for_path(
1621            path,
1622            buffer,
1623            excerpt_ranges,
1624            buffer_snapshot,
1625            new,
1626            counts,
1627            cx,
1628        )
1629    }
1630
1631    pub fn set_anchored_excerpts_for_path(
1632        &self,
1633        buffer: Entity<Buffer>,
1634        ranges: Vec<Range<text::Anchor>>,
1635        context_line_count: u32,
1636        cx: &mut Context<Self>,
1637    ) -> Task<Vec<Range<Anchor>>> {
1638        let buffer_snapshot = buffer.read(cx).snapshot();
1639        let path_key = PathKey::for_buffer(&buffer, cx);
1640        cx.spawn(async move |multi_buffer, cx| {
1641            let snapshot = buffer_snapshot.clone();
1642            let (excerpt_ranges, new, counts) = cx
1643                .background_spawn(async move {
1644                    let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
1645                    let excerpt_ranges =
1646                        build_excerpt_ranges(ranges, context_line_count, &snapshot);
1647                    let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1648                    (excerpt_ranges, new, counts)
1649                })
1650                .await;
1651
1652            multi_buffer
1653                .update(cx, move |multi_buffer, cx| {
1654                    let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
1655                        path_key,
1656                        buffer,
1657                        excerpt_ranges,
1658                        &buffer_snapshot,
1659                        new,
1660                        counts,
1661                        cx,
1662                    );
1663                    ranges
1664                })
1665                .ok()
1666                .unwrap_or_default()
1667        })
1668    }
1669
1670    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1671    fn set_merged_excerpt_ranges_for_path(
1672        &mut self,
1673        path: PathKey,
1674        buffer: Entity<Buffer>,
1675        ranges: Vec<ExcerptRange<Point>>,
1676        buffer_snapshot: &BufferSnapshot,
1677        new: Vec<ExcerptRange<Point>>,
1678        counts: Vec<usize>,
1679        cx: &mut Context<Self>,
1680    ) -> (Vec<Range<Anchor>>, bool) {
1681        let (excerpt_ids, added_a_new_excerpt) =
1682            self.update_path_excerpts(path, buffer, buffer_snapshot, new, cx);
1683
1684        let mut result = Vec::new();
1685        let mut ranges = ranges.into_iter();
1686        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(counts.into_iter()) {
1687            for range in ranges.by_ref().take(range_count) {
1688                let range = Anchor::range_in_buffer(
1689                    excerpt_id,
1690                    buffer_snapshot.remote_id(),
1691                    buffer_snapshot.anchor_before(&range.primary.start)
1692                        ..buffer_snapshot.anchor_after(&range.primary.end),
1693                );
1694                result.push(range)
1695            }
1696        }
1697        (result, added_a_new_excerpt)
1698    }
1699
1700    fn merge_excerpt_ranges<'a>(
1701        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1702    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1703        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1704        let mut counts: Vec<usize> = Vec::new();
1705        for range in expanded_ranges {
1706            if let Some(last_range) = merged_ranges.last_mut() {
1707                debug_assert!(
1708                    last_range.context.start <= range.context.start,
1709                    "Last range: {last_range:?} Range: {range:?}"
1710                );
1711                if last_range.context.end >= range.context.start
1712                    || last_range.context.end.row + 1 == range.context.start.row
1713                {
1714                    last_range.context.end = range.context.end.max(last_range.context.end);
1715                    *counts.last_mut().unwrap() += 1;
1716                    continue;
1717                }
1718            }
1719            merged_ranges.push(range.clone());
1720            counts.push(1);
1721        }
1722        (merged_ranges, counts)
1723    }
1724
1725    fn update_path_excerpts(
1726        &mut self,
1727        path: PathKey,
1728        buffer: Entity<Buffer>,
1729        buffer_snapshot: &BufferSnapshot,
1730        new: Vec<ExcerptRange<Point>>,
1731        cx: &mut Context<Self>,
1732    ) -> (Vec<ExcerptId>, bool) {
1733        let mut insert_after = self
1734            .excerpts_by_path
1735            .range(..path.clone())
1736            .next_back()
1737            .map(|(_, value)| *value.last().unwrap())
1738            .unwrap_or(ExcerptId::min());
1739
1740        let existing = self
1741            .excerpts_by_path
1742            .get(&path)
1743            .cloned()
1744            .unwrap_or_default();
1745
1746        let mut new_iter = new.into_iter().peekable();
1747        let mut existing_iter = existing.into_iter().peekable();
1748
1749        let mut excerpt_ids = Vec::new();
1750        let mut to_remove = Vec::new();
1751        let mut to_insert: Vec<(ExcerptId, ExcerptRange<Point>)> = Vec::new();
1752        let mut added_a_new_excerpt = false;
1753        let snapshot = self.snapshot(cx);
1754
1755        let mut next_excerpt_id =
1756            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1757                last_entry.id.0 + 1
1758            } else {
1759                1
1760            };
1761
1762        let mut next_excerpt_id = move || ExcerptId(post_inc(&mut next_excerpt_id));
1763
1764        let mut excerpts_cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1765        excerpts_cursor.next();
1766
1767        loop {
1768            let new = new_iter.peek();
1769            let existing = if let Some(existing_id) = existing_iter.peek() {
1770                let locator = snapshot.excerpt_locator_for_id(*existing_id);
1771                excerpts_cursor.seek_forward(&Some(locator), Bias::Left);
1772                if let Some(excerpt) = excerpts_cursor.item() {
1773                    if excerpt.buffer_id != buffer_snapshot.remote_id() {
1774                        to_remove.push(*existing_id);
1775                        existing_iter.next();
1776                        continue;
1777                    }
1778                    Some((
1779                        *existing_id,
1780                        excerpt.range.context.to_point(buffer_snapshot),
1781                    ))
1782                } else {
1783                    None
1784                }
1785            } else {
1786                None
1787            };
1788
1789            if let Some((last_id, last)) = to_insert.last_mut() {
1790                if let Some(new) = new
1791                    && last.context.end >= new.context.start
1792                {
1793                    last.context.end = last.context.end.max(new.context.end);
1794                    excerpt_ids.push(*last_id);
1795                    new_iter.next();
1796                    continue;
1797                }
1798                if let Some((existing_id, existing_range)) = &existing
1799                    && last.context.end >= existing_range.start
1800                {
1801                    last.context.end = last.context.end.max(existing_range.end);
1802                    to_remove.push(*existing_id);
1803                    self.snapshot
1804                        .borrow_mut()
1805                        .replaced_excerpts
1806                        .insert(*existing_id, *last_id);
1807                    existing_iter.next();
1808                    continue;
1809                }
1810            }
1811
1812            match (new, existing) {
1813                (None, None) => break,
1814                (None, Some((existing_id, _))) => {
1815                    existing_iter.next();
1816                    to_remove.push(existing_id);
1817                    continue;
1818                }
1819                (Some(_), None) => {
1820                    added_a_new_excerpt = true;
1821                    let new_id = next_excerpt_id();
1822                    excerpt_ids.push(new_id);
1823                    to_insert.push((new_id, new_iter.next().unwrap()));
1824                    continue;
1825                }
1826                (Some(new), Some((_, existing_range))) => {
1827                    if existing_range.end < new.context.start {
1828                        let existing_id = existing_iter.next().unwrap();
1829                        to_remove.push(existing_id);
1830                        continue;
1831                    } else if existing_range.start > new.context.end {
1832                        let new_id = next_excerpt_id();
1833                        excerpt_ids.push(new_id);
1834                        to_insert.push((new_id, new_iter.next().unwrap()));
1835                        continue;
1836                    }
1837
1838                    if existing_range.start == new.context.start
1839                        && existing_range.end == new.context.end
1840                    {
1841                        self.insert_excerpts_with_ids_after(
1842                            insert_after,
1843                            buffer.clone(),
1844                            mem::take(&mut to_insert),
1845                            cx,
1846                        );
1847                        insert_after = existing_iter.next().unwrap();
1848                        excerpt_ids.push(insert_after);
1849                        new_iter.next();
1850                    } else {
1851                        let existing_id = existing_iter.next().unwrap();
1852                        let new_id = next_excerpt_id();
1853                        self.snapshot
1854                            .borrow_mut()
1855                            .replaced_excerpts
1856                            .insert(existing_id, new_id);
1857                        to_remove.push(existing_id);
1858                        let mut range = new_iter.next().unwrap();
1859                        range.context.start = range.context.start.min(existing_range.start);
1860                        range.context.end = range.context.end.max(existing_range.end);
1861                        excerpt_ids.push(new_id);
1862                        to_insert.push((new_id, range));
1863                    }
1864                }
1865            };
1866        }
1867
1868        self.insert_excerpts_with_ids_after(insert_after, buffer, to_insert, cx);
1869        self.remove_excerpts(to_remove, cx);
1870        if excerpt_ids.is_empty() {
1871            self.excerpts_by_path.remove(&path);
1872        } else {
1873            for excerpt_id in &excerpt_ids {
1874                self.paths_by_excerpt.insert(*excerpt_id, path.clone());
1875            }
1876            self.excerpts_by_path
1877                .insert(path, excerpt_ids.iter().dedup().cloned().collect());
1878        }
1879
1880        (excerpt_ids, added_a_new_excerpt)
1881    }
1882
1883    pub fn paths(&self) -> impl Iterator<Item = PathKey> + '_ {
1884        self.excerpts_by_path.keys().cloned()
1885    }
1886
1887    pub fn remove_excerpts_for_path(&mut self, path: PathKey, cx: &mut Context<Self>) {
1888        if let Some(to_remove) = self.excerpts_by_path.remove(&path) {
1889            self.remove_excerpts(to_remove, cx)
1890        }
1891    }
1892
1893    pub fn insert_excerpts_after<O>(
1894        &mut self,
1895        prev_excerpt_id: ExcerptId,
1896        buffer: Entity<Buffer>,
1897        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1898        cx: &mut Context<Self>,
1899    ) -> Vec<ExcerptId>
1900    where
1901        O: text::ToOffset,
1902    {
1903        let mut ids = Vec::new();
1904        let mut next_excerpt_id =
1905            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1906                last_entry.id.0 + 1
1907            } else {
1908                1
1909            };
1910        self.insert_excerpts_with_ids_after(
1911            prev_excerpt_id,
1912            buffer,
1913            ranges.into_iter().map(|range| {
1914                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1915                ids.push(id);
1916                (id, range)
1917            }),
1918            cx,
1919        );
1920        ids
1921    }
1922
1923    pub fn insert_excerpts_with_ids_after<O>(
1924        &mut self,
1925        prev_excerpt_id: ExcerptId,
1926        buffer: Entity<Buffer>,
1927        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1928        cx: &mut Context<Self>,
1929    ) where
1930        O: text::ToOffset,
1931    {
1932        assert_eq!(self.history.transaction_depth, 0);
1933        let mut ranges = ranges.into_iter().peekable();
1934        if ranges.peek().is_none() {
1935            return Default::default();
1936        }
1937
1938        self.sync(cx);
1939
1940        let buffer_snapshot = buffer.read(cx).snapshot();
1941        let buffer_id = buffer_snapshot.remote_id();
1942
1943        let mut buffers = self.buffers.borrow_mut();
1944        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| {
1945            self.buffer_changed_since_sync.replace(true);
1946            buffer.update(cx, |buffer, _| {
1947                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1948            });
1949            BufferState {
1950                last_version: buffer_snapshot.version().clone(),
1951                last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1952                excerpts: Default::default(),
1953                _subscriptions: [
1954                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1955                    cx.subscribe(&buffer, Self::on_buffer_event),
1956                ],
1957                buffer: buffer.clone(),
1958            }
1959        });
1960
1961        let mut snapshot = self.snapshot.borrow_mut();
1962
1963        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1964        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1965        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1966        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1967        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1968
1969        let edit_start = ExcerptOffset::new(new_excerpts.summary().text.len);
1970        new_excerpts.update_last(
1971            |excerpt| {
1972                excerpt.has_trailing_newline = true;
1973            },
1974            (),
1975        );
1976
1977        let next_locator = if let Some(excerpt) = cursor.item() {
1978            excerpt.locator.clone()
1979        } else {
1980            Locator::max()
1981        };
1982
1983        let mut excerpts = Vec::new();
1984        while let Some((id, range)) = ranges.next() {
1985            let locator = Locator::between(&prev_locator, &next_locator);
1986            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1987                buffer_state.excerpts.insert(ix, locator.clone());
1988            }
1989            let range = ExcerptRange {
1990                context: buffer_snapshot.anchor_before(&range.context.start)
1991                    ..buffer_snapshot.anchor_after(&range.context.end),
1992                primary: buffer_snapshot.anchor_before(&range.primary.start)
1993                    ..buffer_snapshot.anchor_after(&range.primary.end),
1994            };
1995            excerpts.push((id, range.clone()));
1996            let excerpt = Excerpt::new(
1997                id,
1998                locator.clone(),
1999                buffer_id,
2000                buffer_snapshot.clone(),
2001                range,
2002                ranges.peek().is_some() || cursor.item().is_some(),
2003            );
2004            new_excerpts.push(excerpt, ());
2005            prev_locator = locator.clone();
2006
2007            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
2008                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
2009            }
2010            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
2011        }
2012
2013        let edit_end = ExcerptOffset::new(new_excerpts.summary().text.len);
2014
2015        let suffix = cursor.suffix();
2016        let changed_trailing_excerpt = suffix.is_empty();
2017        new_excerpts.append(suffix, ());
2018        drop(cursor);
2019        snapshot.excerpts = new_excerpts;
2020        snapshot.excerpt_ids = new_excerpt_ids;
2021        if changed_trailing_excerpt {
2022            snapshot.trailing_excerpt_update_count += 1;
2023        }
2024
2025        self.sync_diff_transforms(
2026            &mut snapshot,
2027            vec![Edit {
2028                old: edit_start..edit_start,
2029                new: edit_start..edit_end,
2030            }],
2031            DiffChangeKind::BufferEdited,
2032        );
2033        cx.emit(Event::Edited {
2034            singleton_buffer_edited: false,
2035            edited_buffer: None,
2036        });
2037        cx.emit(Event::ExcerptsAdded {
2038            buffer,
2039            predecessor: prev_excerpt_id,
2040            excerpts,
2041        });
2042        cx.notify();
2043    }
2044
2045    pub fn clear(&mut self, cx: &mut Context<Self>) {
2046        self.sync(cx);
2047        let ids = self.excerpt_ids();
2048        let removed_buffer_ids = self
2049            .buffers
2050            .borrow_mut()
2051            .drain()
2052            .map(|(id, _)| id)
2053            .collect();
2054        self.excerpts_by_path.clear();
2055        self.paths_by_excerpt.clear();
2056        let mut snapshot = self.snapshot.borrow_mut();
2057        let start = ExcerptOffset::new(0);
2058        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2059        snapshot.excerpts = Default::default();
2060        snapshot.trailing_excerpt_update_count += 1;
2061        snapshot.is_dirty = false;
2062        snapshot.has_deleted_file = false;
2063        snapshot.has_conflict = false;
2064        snapshot.replaced_excerpts.clear();
2065
2066        self.sync_diff_transforms(
2067            &mut snapshot,
2068            vec![Edit {
2069                old: start..prev_len,
2070                new: start..start,
2071            }],
2072            DiffChangeKind::BufferEdited,
2073        );
2074        cx.emit(Event::Edited {
2075            singleton_buffer_edited: false,
2076            edited_buffer: None,
2077        });
2078        cx.emit(Event::ExcerptsRemoved {
2079            ids,
2080            removed_buffer_ids,
2081        });
2082        cx.notify();
2083    }
2084
2085    pub fn excerpts_for_buffer(
2086        &self,
2087        buffer_id: BufferId,
2088        cx: &App,
2089    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2090        let mut excerpts = Vec::new();
2091        let snapshot = self.read(cx);
2092        let buffers = self.buffers.borrow();
2093        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
2094        if let Some(locators) = buffers.get(&buffer_id).map(|state| &state.excerpts) {
2095            for locator in locators {
2096                cursor.seek_forward(&Some(locator), Bias::Left);
2097                if let Some(excerpt) = cursor.item()
2098                    && excerpt.locator == *locator
2099                {
2100                    excerpts.push((excerpt.id, excerpt.range.clone()));
2101                }
2102            }
2103        }
2104
2105        excerpts
2106    }
2107
2108    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2109        let snapshot = self.read(cx);
2110        let buffers = self.buffers.borrow();
2111        let mut excerpts = snapshot
2112            .excerpts
2113            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
2114        let mut diff_transforms = snapshot
2115            .diff_transforms
2116            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
2117        diff_transforms.next();
2118        let locators = buffers
2119            .get(&buffer_id)
2120            .into_iter()
2121            .flat_map(|state| &state.excerpts);
2122        let mut result = Vec::new();
2123        for locator in locators {
2124            excerpts.seek_forward(&Some(locator), Bias::Left);
2125            if let Some(excerpt) = excerpts.item()
2126                && excerpt.locator == *locator
2127            {
2128                let excerpt_start = excerpts.start().1.clone();
2129                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2130
2131                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2132                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2133                let start = diff_transforms.start().1.0 + overshoot;
2134
2135                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2136                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2137                let end = diff_transforms.start().1.0 + overshoot;
2138
2139                result.push(start..end)
2140            }
2141        }
2142        result
2143    }
2144
2145    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2146        self.snapshot
2147            .borrow()
2148            .excerpts
2149            .iter()
2150            .map(|entry| entry.buffer_id)
2151            .collect()
2152    }
2153
2154    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2155        self.snapshot
2156            .borrow()
2157            .excerpts
2158            .iter()
2159            .map(|entry| entry.id)
2160            .collect()
2161    }
2162
2163    pub fn excerpt_containing(
2164        &self,
2165        position: impl ToOffset,
2166        cx: &App,
2167    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2168        let snapshot = self.read(cx);
2169        let offset = position.to_offset(&snapshot);
2170
2171        let mut cursor = snapshot.cursor::<usize>();
2172        cursor.seek(&offset);
2173        cursor
2174            .excerpt()
2175            .or_else(|| snapshot.excerpts.last())
2176            .map(|excerpt| {
2177                (
2178                    excerpt.id,
2179                    self.buffers
2180                        .borrow()
2181                        .get(&excerpt.buffer_id)
2182                        .unwrap()
2183                        .buffer
2184                        .clone(),
2185                    excerpt.range.context.clone(),
2186                )
2187            })
2188    }
2189
2190    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2191        if let Some(buffer_id) = anchor.buffer_id {
2192            self.buffer(buffer_id)
2193        } else {
2194            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2195            Some(buffer)
2196        }
2197    }
2198
2199    // If point is at the end of the buffer, the last excerpt is returned
2200    pub fn point_to_buffer_offset<T: ToOffset>(
2201        &self,
2202        point: T,
2203        cx: &App,
2204    ) -> Option<(Entity<Buffer>, usize)> {
2205        let snapshot = self.read(cx);
2206        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2207        Some((
2208            self.buffers
2209                .borrow()
2210                .get(&buffer.remote_id())?
2211                .buffer
2212                .clone(),
2213            offset,
2214        ))
2215    }
2216
2217    // If point is at the end of the buffer, the last excerpt is returned
2218    pub fn point_to_buffer_point<T: ToPoint>(
2219        &self,
2220        point: T,
2221        cx: &App,
2222    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2223        let snapshot = self.read(cx);
2224        let (buffer, point, is_main_buffer) =
2225            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2226        Some((
2227            self.buffers
2228                .borrow()
2229                .get(&buffer.remote_id())?
2230                .buffer
2231                .clone(),
2232            point,
2233            is_main_buffer,
2234        ))
2235    }
2236
2237    pub fn buffer_point_to_anchor(
2238        &self,
2239        buffer: &Entity<Buffer>,
2240        point: Point,
2241        cx: &App,
2242    ) -> Option<Anchor> {
2243        let mut found = None;
2244        let snapshot = buffer.read(cx).snapshot();
2245        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2246            let start = range.context.start.to_point(&snapshot);
2247            let end = range.context.end.to_point(&snapshot);
2248            if start <= point && point < end {
2249                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2250                break;
2251            }
2252            if point < start {
2253                found = Some((start, excerpt_id));
2254            }
2255            if point > end {
2256                found = Some((end, excerpt_id));
2257            }
2258        }
2259
2260        found.map(|(point, excerpt_id)| {
2261            let text_anchor = snapshot.anchor_after(point);
2262            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2263        })
2264    }
2265
2266    pub fn remove_excerpts(
2267        &mut self,
2268        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2269        cx: &mut Context<Self>,
2270    ) {
2271        self.sync(cx);
2272        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2273        if ids.is_empty() {
2274            return;
2275        }
2276
2277        let mut buffers = self.buffers.borrow_mut();
2278        let mut snapshot = self.snapshot.borrow_mut();
2279        let mut new_excerpts = SumTree::default();
2280        let mut cursor = snapshot
2281            .excerpts
2282            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2283        let mut edits = Vec::new();
2284        let mut excerpt_ids = ids.iter().copied().peekable();
2285        let mut removed_buffer_ids = Vec::new();
2286
2287        while let Some(excerpt_id) = excerpt_ids.next() {
2288            self.paths_by_excerpt.remove(&excerpt_id);
2289            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2290            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2291            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2292
2293            if let Some(mut excerpt) = cursor.item() {
2294                if excerpt.id != excerpt_id {
2295                    continue;
2296                }
2297                let mut old_start = cursor.start().1;
2298
2299                // Skip over the removed excerpt.
2300                'remove_excerpts: loop {
2301                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2302                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2303                        if buffer_state.excerpts.is_empty() {
2304                            log::debug!(
2305                                "removing buffer and diff for buffer {}",
2306                                excerpt.buffer_id
2307                            );
2308                            buffers.remove(&excerpt.buffer_id);
2309                            removed_buffer_ids.push(excerpt.buffer_id);
2310                        }
2311                    }
2312                    cursor.next();
2313
2314                    // Skip over any subsequent excerpts that are also removed.
2315                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2316                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2317                        if let Some(next_excerpt) = cursor.item()
2318                            && next_excerpt.locator == *next_locator
2319                        {
2320                            excerpt_ids.next();
2321                            excerpt = next_excerpt;
2322                            continue 'remove_excerpts;
2323                        }
2324                    }
2325
2326                    break;
2327                }
2328
2329                // When removing the last excerpt, remove the trailing newline from
2330                // the previous excerpt.
2331                if cursor.item().is_none() && old_start.value > 0 {
2332                    old_start.value -= 1;
2333                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2334                }
2335
2336                // Push an edit for the removal of this run of excerpts.
2337                let old_end = cursor.start().1;
2338                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2339                edits.push(Edit {
2340                    old: old_start..old_end,
2341                    new: new_start..new_start,
2342                });
2343            }
2344        }
2345        let suffix = cursor.suffix();
2346        let changed_trailing_excerpt = suffix.is_empty();
2347        new_excerpts.append(suffix, ());
2348        drop(cursor);
2349        snapshot.excerpts = new_excerpts;
2350        for buffer_id in &removed_buffer_ids {
2351            self.diffs.remove(buffer_id);
2352            snapshot.diffs.remove(buffer_id);
2353        }
2354
2355        if changed_trailing_excerpt {
2356            snapshot.trailing_excerpt_update_count += 1;
2357        }
2358
2359        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2360        self.buffer_changed_since_sync.replace(true);
2361        cx.emit(Event::Edited {
2362            singleton_buffer_edited: false,
2363            edited_buffer: None,
2364        });
2365        cx.emit(Event::ExcerptsRemoved {
2366            ids,
2367            removed_buffer_ids,
2368        });
2369        cx.notify();
2370    }
2371
2372    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2373        &self,
2374        anchors: Anchors,
2375        cx: &mut Context<Self>,
2376    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2377        let borrow = self.buffers.borrow();
2378        let mut error = None;
2379        let mut futures = Vec::new();
2380        for anchor in anchors {
2381            if let Some(buffer_id) = anchor.buffer_id {
2382                if let Some(buffer) = borrow.get(&buffer_id) {
2383                    buffer.buffer.update(cx, |buffer, _| {
2384                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2385                    });
2386                } else {
2387                    error = Some(anyhow!(
2388                        "buffer {buffer_id} is not part of this multi-buffer"
2389                    ));
2390                    break;
2391                }
2392            }
2393        }
2394        async move {
2395            if let Some(error) = error {
2396                Err(error)?;
2397            }
2398            for future in futures {
2399                future.await?;
2400            }
2401            Ok(())
2402        }
2403    }
2404
2405    pub fn text_anchor_for_position<T: ToOffset>(
2406        &self,
2407        position: T,
2408        cx: &App,
2409    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2410        let snapshot = self.read(cx);
2411        let anchor = snapshot.anchor_before(position);
2412        let buffer = self
2413            .buffers
2414            .borrow()
2415            .get(&anchor.buffer_id?)?
2416            .buffer
2417            .clone();
2418        Some((buffer, anchor.text_anchor))
2419    }
2420
2421    fn on_buffer_event(
2422        &mut self,
2423        buffer: Entity<Buffer>,
2424        event: &language::BufferEvent,
2425        cx: &mut Context<Self>,
2426    ) {
2427        use language::BufferEvent;
2428        cx.emit(match event {
2429            BufferEvent::Edited => Event::Edited {
2430                singleton_buffer_edited: true,
2431                edited_buffer: Some(buffer),
2432            },
2433            BufferEvent::DirtyChanged => Event::DirtyChanged,
2434            BufferEvent::Saved => Event::Saved,
2435            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2436            BufferEvent::Reloaded => Event::Reloaded,
2437            BufferEvent::LanguageChanged => Event::LanguageChanged(buffer.read(cx).remote_id()),
2438            BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2439            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2440            BufferEvent::CapabilityChanged => {
2441                self.capability = buffer.read(cx).capability();
2442                return;
2443            }
2444            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2445        });
2446    }
2447
2448    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2449        self.sync(cx);
2450        let mut snapshot = self.snapshot.borrow_mut();
2451        let diff = diff.read(cx);
2452        let buffer_id = diff.buffer_id;
2453        let diff = diff.snapshot(cx);
2454        snapshot.diffs.insert(buffer_id, diff);
2455    }
2456
2457    fn buffer_diff_changed(
2458        &mut self,
2459        diff: Entity<BufferDiff>,
2460        range: Range<text::Anchor>,
2461        cx: &mut Context<Self>,
2462    ) {
2463        self.sync(cx);
2464        self.buffer_changed_since_sync.replace(true);
2465
2466        let diff = diff.read(cx);
2467        let buffer_id = diff.buffer_id;
2468        let buffers = self.buffers.borrow();
2469        let Some(buffer_state) = buffers.get(&buffer_id) else {
2470            return;
2471        };
2472
2473        let buffer = buffer_state.buffer.read(cx);
2474        let diff_change_range = range.to_offset(buffer);
2475
2476        let new_diff = diff.snapshot(cx);
2477        let mut snapshot = self.snapshot.borrow_mut();
2478        let base_text_changed = snapshot
2479            .diffs
2480            .get(&buffer_id)
2481            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2482
2483        snapshot.diffs.insert(buffer_id, new_diff);
2484
2485        let mut excerpt_edits = Vec::new();
2486        for locator in &buffer_state.excerpts {
2487            let mut cursor = snapshot
2488                .excerpts
2489                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2490            cursor.seek_forward(&Some(locator), Bias::Left);
2491            if let Some(excerpt) = cursor.item()
2492                && excerpt.locator == *locator
2493            {
2494                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2495                if diff_change_range.end < excerpt_buffer_range.start
2496                    || diff_change_range.start > excerpt_buffer_range.end
2497                {
2498                    continue;
2499                }
2500                let excerpt_start = cursor.start().1;
2501                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2502                let diff_change_start_in_excerpt = ExcerptOffset::new(
2503                    diff_change_range
2504                        .start
2505                        .saturating_sub(excerpt_buffer_range.start),
2506                );
2507                let diff_change_end_in_excerpt = ExcerptOffset::new(
2508                    diff_change_range
2509                        .end
2510                        .saturating_sub(excerpt_buffer_range.start),
2511                );
2512                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2513                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2514                excerpt_edits.push(Edit {
2515                    old: edit_start..edit_end,
2516                    new: edit_start..edit_end,
2517                });
2518            }
2519        }
2520
2521        self.sync_diff_transforms(
2522            &mut snapshot,
2523            excerpt_edits,
2524            DiffChangeKind::DiffUpdated {
2525                base_changed: base_text_changed,
2526            },
2527        );
2528        cx.emit(Event::Edited {
2529            singleton_buffer_edited: false,
2530            edited_buffer: None,
2531        });
2532    }
2533
2534    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2535        self.buffers
2536            .borrow()
2537            .values()
2538            .map(|state| state.buffer.clone())
2539            .collect()
2540    }
2541
2542    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2543        self.buffers.borrow().keys().copied().collect()
2544    }
2545
2546    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2547        self.buffers
2548            .borrow()
2549            .get(&buffer_id)
2550            .map(|state| state.buffer.clone())
2551    }
2552
2553    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2554        self.point_to_buffer_offset(point, cx)
2555            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2556    }
2557
2558    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2559        let buffer_id = self
2560            .snapshot
2561            .borrow()
2562            .excerpts
2563            .first()
2564            .map(|excerpt| excerpt.buffer.remote_id());
2565        buffer_id
2566            .and_then(|buffer_id| self.buffer(buffer_id))
2567            .map(|buffer| {
2568                let buffer = buffer.read(cx);
2569                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2570            })
2571            .unwrap_or_else(move || self.language_settings_at(0, cx))
2572    }
2573
2574    pub fn language_settings_at<'a, T: ToOffset>(
2575        &'a self,
2576        point: T,
2577        cx: &'a App,
2578    ) -> Cow<'a, LanguageSettings> {
2579        let mut language = None;
2580        let mut file = None;
2581        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2582            let buffer = buffer.read(cx);
2583            language = buffer.language_at(offset);
2584            file = buffer.file();
2585        }
2586        language_settings(language.map(|l| l.name()), file, cx)
2587    }
2588
2589    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2590        self.buffers
2591            .borrow()
2592            .values()
2593            .for_each(|state| f(&state.buffer))
2594    }
2595
2596    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2597        if let Some(title) = self.title.as_ref() {
2598            return title.into();
2599        }
2600
2601        if let Some(buffer) = self.as_singleton() {
2602            let buffer = buffer.read(cx);
2603
2604            if let Some(file) = buffer.file() {
2605                return file.file_name(cx).into();
2606            }
2607
2608            if let Some(title) = self.buffer_content_title(buffer) {
2609                return title;
2610            }
2611        };
2612
2613        "untitled".into()
2614    }
2615
2616    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2617        let mut is_leading_whitespace = true;
2618        let mut count = 0;
2619        let mut prev_was_space = false;
2620        let mut title = String::new();
2621
2622        for ch in buffer.snapshot().chars() {
2623            if is_leading_whitespace && ch.is_whitespace() {
2624                continue;
2625            }
2626
2627            is_leading_whitespace = false;
2628
2629            if ch == '\n' || count >= 40 {
2630                break;
2631            }
2632
2633            if ch.is_whitespace() {
2634                if !prev_was_space {
2635                    title.push(' ');
2636                    count += 1;
2637                    prev_was_space = true;
2638                }
2639            } else {
2640                title.push(ch);
2641                count += 1;
2642                prev_was_space = false;
2643            }
2644        }
2645
2646        let title = title.trim_end().to_string();
2647
2648        if title.is_empty() {
2649            return None;
2650        }
2651
2652        Some(title.into())
2653    }
2654
2655    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2656        self.title = Some(title);
2657        cx.notify();
2658    }
2659
2660    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2661    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2662        for buffer_state in self.buffers.borrow().values() {
2663            buffer_state
2664                .buffer
2665                .update(cx, |buffer, _cx| buffer.refresh_preview());
2666        }
2667    }
2668
2669    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2670    pub fn preserve_preview(&self, cx: &App) -> bool {
2671        self.buffers
2672            .borrow()
2673            .values()
2674            .all(|state| state.buffer.read(cx).preserve_preview())
2675    }
2676
2677    #[cfg(any(test, feature = "test-support"))]
2678    pub fn is_parsing(&self, cx: &App) -> bool {
2679        self.as_singleton().unwrap().read(cx).is_parsing()
2680    }
2681
2682    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2683        let buffer_id = diff.read(cx).buffer_id;
2684        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2685        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2686    }
2687
2688    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2689        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2690    }
2691
2692    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2693        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2694    }
2695
2696    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2697        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2698    }
2699
2700    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2701        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2702        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2703    }
2704
2705    pub fn all_diff_hunks_expanded(&self) -> bool {
2706        self.snapshot.borrow().all_diff_hunks_expanded
2707    }
2708
2709    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2710        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2711        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2712    }
2713
2714    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2715        self.read(cx)
2716            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2717            .nth(1)
2718            .is_some()
2719    }
2720
2721    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2722        let snapshot = self.read(cx);
2723        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2724        let offset_range = range.to_offset(&snapshot);
2725        cursor.seek(&offset_range.start, Bias::Left);
2726        while let Some(item) = cursor.item() {
2727            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2728                break;
2729            }
2730            if item.hunk_info().is_some() {
2731                return true;
2732            }
2733            cursor.next();
2734        }
2735        false
2736    }
2737
2738    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2739        let snapshot = self.read(cx);
2740        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2741        for range in ranges {
2742            let range = range.to_point(&snapshot);
2743            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2744            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2745            let start = start.saturating_sub(1);
2746            let end = snapshot.len().min(end + 1);
2747            cursor.seek(&start, Bias::Right);
2748            while let Some(item) = cursor.item() {
2749                if *cursor.start() >= end {
2750                    break;
2751                }
2752                if item.hunk_info().is_some() {
2753                    return true;
2754                }
2755                cursor.next();
2756            }
2757        }
2758        false
2759    }
2760
2761    pub fn expand_or_collapse_diff_hunks_inner(
2762        &mut self,
2763        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2764        expand: bool,
2765        cx: &mut Context<Self>,
2766    ) {
2767        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2768            return;
2769        }
2770        self.sync(cx);
2771        let mut snapshot = self.snapshot.borrow_mut();
2772        let mut excerpt_edits = Vec::new();
2773        let mut last_hunk_row = None;
2774        for (range, end_excerpt_id) in ranges {
2775            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2776                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2777                    continue;
2778                }
2779                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2780                    continue;
2781                }
2782                let start = Anchor::in_buffer(
2783                    diff_hunk.excerpt_id,
2784                    diff_hunk.buffer_id,
2785                    diff_hunk.buffer_range.start,
2786                );
2787                let end = Anchor::in_buffer(
2788                    diff_hunk.excerpt_id,
2789                    diff_hunk.buffer_id,
2790                    diff_hunk.buffer_range.end,
2791                );
2792                let start = snapshot.excerpt_offset_for_anchor(&start);
2793                let end = snapshot.excerpt_offset_for_anchor(&end);
2794                last_hunk_row = Some(diff_hunk.row_range.start);
2795                excerpt_edits.push(text::Edit {
2796                    old: start..end,
2797                    new: start..end,
2798                });
2799            }
2800        }
2801
2802        self.sync_diff_transforms(
2803            &mut snapshot,
2804            excerpt_edits,
2805            DiffChangeKind::ExpandOrCollapseHunks { expand },
2806        );
2807        cx.emit(Event::DiffHunksToggled);
2808        cx.emit(Event::Edited {
2809            singleton_buffer_edited: false,
2810            edited_buffer: None,
2811        });
2812    }
2813
2814    pub fn expand_or_collapse_diff_hunks(
2815        &mut self,
2816        ranges: Vec<Range<Anchor>>,
2817        expand: bool,
2818        cx: &mut Context<Self>,
2819    ) {
2820        let snapshot = self.snapshot.borrow().clone();
2821        let ranges = ranges.iter().map(move |range| {
2822            let end_excerpt_id = range.end.excerpt_id;
2823            let range = range.to_point(&snapshot);
2824            let mut peek_end = range.end;
2825            if range.end.row < snapshot.max_row().0 {
2826                peek_end = Point::new(range.end.row + 1, 0);
2827            };
2828            (range.start..peek_end, end_excerpt_id)
2829        });
2830        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2831    }
2832
2833    pub fn resize_excerpt(
2834        &mut self,
2835        id: ExcerptId,
2836        range: Range<text::Anchor>,
2837        cx: &mut Context<Self>,
2838    ) {
2839        self.sync(cx);
2840
2841        let mut snapshot = self.snapshot.borrow_mut();
2842        let locator = snapshot.excerpt_locator_for_id(id);
2843        let mut new_excerpts = SumTree::default();
2844        let mut cursor = snapshot
2845            .excerpts
2846            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2847        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2848
2849        let prefix = cursor.slice(&Some(locator), Bias::Left);
2850        new_excerpts.append(prefix, ());
2851
2852        let mut excerpt = cursor.item().unwrap().clone();
2853        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2854
2855        excerpt.range.context.start = range.start;
2856        excerpt.range.context.end = range.end;
2857        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2858
2859        excerpt.text_summary = excerpt
2860            .buffer
2861            .text_summary_for_range(excerpt.range.context.clone());
2862
2863        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2864        let old_start_offset = cursor.start().1;
2865        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2866        let edit = Edit {
2867            old: old_start_offset..old_start_offset + old_text_len,
2868            new: new_start_offset..new_start_offset + new_text_len,
2869        };
2870
2871        if let Some(last_edit) = edits.last_mut() {
2872            if last_edit.old.end == edit.old.start {
2873                last_edit.old.end = edit.old.end;
2874                last_edit.new.end = edit.new.end;
2875            } else {
2876                edits.push(edit);
2877            }
2878        } else {
2879            edits.push(edit);
2880        }
2881
2882        new_excerpts.push(excerpt, ());
2883
2884        cursor.next();
2885
2886        new_excerpts.append(cursor.suffix(), ());
2887
2888        drop(cursor);
2889        snapshot.excerpts = new_excerpts;
2890
2891        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2892        cx.emit(Event::Edited {
2893            singleton_buffer_edited: false,
2894            edited_buffer: None,
2895        });
2896        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2897        cx.notify();
2898    }
2899
2900    pub fn expand_excerpts(
2901        &mut self,
2902        ids: impl IntoIterator<Item = ExcerptId>,
2903        line_count: u32,
2904        direction: ExpandExcerptDirection,
2905        cx: &mut Context<Self>,
2906    ) {
2907        if line_count == 0 {
2908            return;
2909        }
2910        self.sync(cx);
2911        if !self.excerpts_by_path.is_empty() {
2912            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2913            return;
2914        }
2915        let mut snapshot = self.snapshot.borrow_mut();
2916
2917        let ids = ids.into_iter().collect::<Vec<_>>();
2918        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2919        let mut new_excerpts = SumTree::default();
2920        let mut cursor = snapshot
2921            .excerpts
2922            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2923        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2924
2925        for locator in &locators {
2926            let prefix = cursor.slice(&Some(locator), Bias::Left);
2927            new_excerpts.append(prefix, ());
2928
2929            let mut excerpt = cursor.item().unwrap().clone();
2930            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2931
2932            let up_line_count = if direction.should_expand_up() {
2933                line_count
2934            } else {
2935                0
2936            };
2937
2938            let start_row = excerpt
2939                .range
2940                .context
2941                .start
2942                .to_point(&excerpt.buffer)
2943                .row
2944                .saturating_sub(up_line_count);
2945            let start_point = Point::new(start_row, 0);
2946            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2947
2948            let down_line_count = if direction.should_expand_down() {
2949                line_count
2950            } else {
2951                0
2952            };
2953
2954            let mut end_point = excerpt.buffer.clip_point(
2955                excerpt.range.context.end.to_point(&excerpt.buffer)
2956                    + Point::new(down_line_count, 0),
2957                Bias::Left,
2958            );
2959            end_point.column = excerpt.buffer.line_len(end_point.row);
2960            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2961            excerpt.max_buffer_row = end_point.row;
2962
2963            excerpt.text_summary = excerpt
2964                .buffer
2965                .text_summary_for_range(excerpt.range.context.clone());
2966
2967            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2968            let old_start_offset = cursor.start().1;
2969            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2970            let edit = Edit {
2971                old: old_start_offset..old_start_offset + old_text_len,
2972                new: new_start_offset..new_start_offset + new_text_len,
2973            };
2974
2975            if let Some(last_edit) = edits.last_mut() {
2976                if last_edit.old.end == edit.old.start {
2977                    last_edit.old.end = edit.old.end;
2978                    last_edit.new.end = edit.new.end;
2979                } else {
2980                    edits.push(edit);
2981                }
2982            } else {
2983                edits.push(edit);
2984            }
2985
2986            new_excerpts.push(excerpt, ());
2987
2988            cursor.next();
2989        }
2990
2991        new_excerpts.append(cursor.suffix(), ());
2992
2993        drop(cursor);
2994        snapshot.excerpts = new_excerpts;
2995
2996        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2997        cx.emit(Event::Edited {
2998            singleton_buffer_edited: false,
2999            edited_buffer: None,
3000        });
3001        cx.emit(Event::ExcerptsExpanded { ids });
3002        cx.notify();
3003    }
3004
3005    fn sync(&self, cx: &App) {
3006        let changed = self.buffer_changed_since_sync.replace(false);
3007        if !changed {
3008            return;
3009        }
3010
3011        let mut snapshot = self.snapshot.borrow_mut();
3012        let mut excerpts_to_edit = Vec::new();
3013        let mut non_text_state_updated = false;
3014        let mut is_dirty = false;
3015        let mut has_deleted_file = false;
3016        let mut has_conflict = false;
3017        let mut edited = false;
3018        let mut buffers = self.buffers.borrow_mut();
3019        for buffer_state in buffers.values_mut() {
3020            let buffer = buffer_state.buffer.read(cx);
3021            let version = buffer.version();
3022            let non_text_state_update_count = buffer.non_text_state_update_count();
3023
3024            let buffer_edited = version.changed_since(&buffer_state.last_version);
3025            let buffer_non_text_state_updated =
3026                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3027            if buffer_edited || buffer_non_text_state_updated {
3028                buffer_state.last_version = version;
3029                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3030                excerpts_to_edit.extend(
3031                    buffer_state
3032                        .excerpts
3033                        .iter()
3034                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3035                );
3036            }
3037
3038            edited |= buffer_edited;
3039            non_text_state_updated |= buffer_non_text_state_updated;
3040            is_dirty |= buffer.is_dirty();
3041            has_deleted_file |= buffer
3042                .file()
3043                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3044            has_conflict |= buffer.has_conflict();
3045        }
3046        if edited {
3047            snapshot.edit_count += 1;
3048        }
3049        if non_text_state_updated {
3050            snapshot.non_text_state_update_count += 1;
3051        }
3052        snapshot.is_dirty = is_dirty;
3053        snapshot.has_deleted_file = has_deleted_file;
3054        snapshot.has_conflict = has_conflict;
3055
3056        for (id, diff) in self.diffs.iter() {
3057            if snapshot.diffs.get(id).is_none() {
3058                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3059            }
3060        }
3061
3062        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3063
3064        let mut edits = Vec::new();
3065        let mut new_excerpts = SumTree::default();
3066        let mut cursor = snapshot
3067            .excerpts
3068            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3069
3070        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3071            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3072            let old_excerpt = cursor.item().unwrap();
3073            let buffer = buffer.read(cx);
3074            let buffer_id = buffer.remote_id();
3075
3076            let mut new_excerpt;
3077            if buffer_edited {
3078                edits.extend(
3079                    buffer
3080                        .edits_since_in_range::<usize>(
3081                            old_excerpt.buffer.version(),
3082                            old_excerpt.range.context.clone(),
3083                        )
3084                        .map(|edit| {
3085                            let excerpt_old_start = cursor.start().1;
3086                            let excerpt_new_start =
3087                                ExcerptOffset::new(new_excerpts.summary().text.len);
3088                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3089                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3090                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3091                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3092                            Edit {
3093                                old: old_start..old_end,
3094                                new: new_start..new_end,
3095                            }
3096                        }),
3097                );
3098
3099                new_excerpt = Excerpt::new(
3100                    old_excerpt.id,
3101                    locator.clone(),
3102                    buffer_id,
3103                    buffer.snapshot(),
3104                    old_excerpt.range.clone(),
3105                    old_excerpt.has_trailing_newline,
3106                );
3107            } else {
3108                new_excerpt = old_excerpt.clone();
3109                new_excerpt.buffer = buffer.snapshot();
3110            }
3111
3112            new_excerpts.push(new_excerpt, ());
3113            cursor.next();
3114        }
3115        new_excerpts.append(cursor.suffix(), ());
3116
3117        drop(cursor);
3118        snapshot.excerpts = new_excerpts;
3119
3120        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3121    }
3122
3123    fn sync_diff_transforms(
3124        &self,
3125        snapshot: &mut MultiBufferSnapshot,
3126        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3127        change_kind: DiffChangeKind,
3128    ) {
3129        if excerpt_edits.is_empty() {
3130            return;
3131        }
3132
3133        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3134        let mut old_diff_transforms = snapshot
3135            .diff_transforms
3136            .cursor::<Dimensions<ExcerptOffset, usize>>(());
3137        let mut new_diff_transforms = SumTree::default();
3138        let mut old_expanded_hunks = HashSet::default();
3139        let mut output_edits = Vec::new();
3140        let mut output_delta = 0_isize;
3141        let mut at_transform_boundary = true;
3142        let mut end_of_current_insert = None;
3143
3144        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3145        while let Some(edit) = excerpt_edits.next() {
3146            excerpts.seek_forward(&edit.new.start, Bias::Right);
3147            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3148                excerpts.prev();
3149            }
3150
3151            // Keep any transforms that are before the edit.
3152            if at_transform_boundary {
3153                at_transform_boundary = false;
3154                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3155                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3156                if let Some(transform) = old_diff_transforms.item()
3157                    && old_diff_transforms.end().0 == edit.old.start
3158                    && old_diff_transforms.start().0 < edit.old.start
3159                {
3160                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3161                    old_diff_transforms.next();
3162                }
3163            }
3164
3165            // Compute the start of the edit in output coordinates.
3166            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3167            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3168            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3169
3170            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3171                &edit,
3172                &mut excerpts,
3173                &mut old_diff_transforms,
3174                &mut new_diff_transforms,
3175                &mut end_of_current_insert,
3176                &mut old_expanded_hunks,
3177                snapshot,
3178                change_kind,
3179            );
3180
3181            // Compute the end of the edit in output coordinates.
3182            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3183            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3184            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3185            let edit_new_end =
3186                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3187            let output_edit = Edit {
3188                old: edit_old_start..edit_old_end,
3189                new: edit_new_start..edit_new_end,
3190            };
3191
3192            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3193            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3194            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3195                output_edits.push(output_edit);
3196            }
3197
3198            // If this is the last edit that intersects the current diff transform,
3199            // then recreate the content up to the end of this transform, to prepare
3200            // for reusing additional slices of the old transforms.
3201            if excerpt_edits
3202                .peek()
3203                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3204            {
3205                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3206                    && match old_diff_transforms.item() {
3207                        Some(DiffTransform::BufferContent {
3208                            inserted_hunk_info: Some(hunk),
3209                            ..
3210                        }) => excerpts.item().is_some_and(|excerpt| {
3211                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3212                        }),
3213                        _ => true,
3214                    };
3215
3216                let mut excerpt_offset = edit.new.end;
3217                if !keep_next_old_transform {
3218                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3219                    old_diff_transforms.next();
3220                }
3221
3222                old_expanded_hunks.clear();
3223                self.push_buffer_content_transform(
3224                    snapshot,
3225                    &mut new_diff_transforms,
3226                    excerpt_offset,
3227                    end_of_current_insert,
3228                );
3229                at_transform_boundary = true;
3230            }
3231        }
3232
3233        // Keep any transforms that are after the last edit.
3234        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3235
3236        // Ensure there's always at least one buffer content transform.
3237        if new_diff_transforms.is_empty() {
3238            new_diff_transforms.push(
3239                DiffTransform::BufferContent {
3240                    summary: Default::default(),
3241                    inserted_hunk_info: None,
3242                },
3243                (),
3244            );
3245        }
3246
3247        self.subscriptions.publish(output_edits);
3248        drop(old_diff_transforms);
3249        drop(excerpts);
3250        snapshot.diff_transforms = new_diff_transforms;
3251        snapshot.edit_count += 1;
3252
3253        #[cfg(any(test, feature = "test-support"))]
3254        snapshot.check_invariants();
3255    }
3256
3257    fn recompute_diff_transforms_for_edit(
3258        &self,
3259        edit: &Edit<TypedOffset<Excerpt>>,
3260        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3261        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3262        new_diff_transforms: &mut SumTree<DiffTransform>,
3263        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3264        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3265        snapshot: &MultiBufferSnapshot,
3266        change_kind: DiffChangeKind,
3267    ) -> bool {
3268        log::trace!(
3269            "recomputing diff transform for edit {:?} => {:?}",
3270            edit.old.start.value..edit.old.end.value,
3271            edit.new.start.value..edit.new.end.value
3272        );
3273
3274        // Record which hunks were previously expanded.
3275        while let Some(item) = old_diff_transforms.item() {
3276            if let Some(hunk_info) = item.hunk_info() {
3277                log::trace!(
3278                    "previously expanded hunk at {}",
3279                    old_diff_transforms.start().0
3280                );
3281                old_expanded_hunks.insert(hunk_info);
3282            }
3283            if old_diff_transforms.end().0 > edit.old.end {
3284                break;
3285            }
3286            old_diff_transforms.next();
3287        }
3288
3289        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3290        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3291        if old_expanded_hunks.is_empty()
3292            && change_kind == DiffChangeKind::BufferEdited
3293            && !all_diff_hunks_expanded
3294        {
3295            return false;
3296        }
3297
3298        // Visit each excerpt that intersects the edit.
3299        let mut did_expand_hunks = false;
3300        while let Some(excerpt) = excerpts.item() {
3301            // Recompute the expanded hunks in the portion of the excerpt that
3302            // intersects the edit.
3303            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3304                let buffer = &excerpt.buffer;
3305                let excerpt_start = *excerpts.start();
3306                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3307                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3308                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3309                let edit_buffer_start =
3310                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3311                let edit_buffer_end =
3312                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3313                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3314                let edit_anchor_range =
3315                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3316
3317                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3318                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3319                        continue;
3320                    }
3321
3322                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3323                    if hunk_buffer_range.start < excerpt_buffer_start {
3324                        log::trace!("skipping hunk that starts before excerpt");
3325                        continue;
3326                    }
3327
3328                    let hunk_info = DiffTransformHunkInfo {
3329                        excerpt_id: excerpt.id,
3330                        hunk_start_anchor: hunk.buffer_range.start,
3331                        hunk_secondary_status: hunk.secondary_status,
3332                    };
3333
3334                    let hunk_excerpt_start = excerpt_start
3335                        + ExcerptOffset::new(
3336                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3337                        );
3338                    let hunk_excerpt_end = excerpt_end.min(
3339                        excerpt_start
3340                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3341                    );
3342
3343                    self.push_buffer_content_transform(
3344                        snapshot,
3345                        new_diff_transforms,
3346                        hunk_excerpt_start,
3347                        *end_of_current_insert,
3348                    );
3349
3350                    // For every existing hunk, determine if it was previously expanded
3351                    // and if it should currently be expanded.
3352                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3353                    let should_expand_hunk = match &change_kind {
3354                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3355                            was_previously_expanded || all_diff_hunks_expanded
3356                        }
3357                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3358                            let intersects = hunk_buffer_range.is_empty()
3359                                || hunk_buffer_range.end > edit_buffer_start;
3360                            if *expand {
3361                                intersects || was_previously_expanded || all_diff_hunks_expanded
3362                            } else {
3363                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3364                            }
3365                        }
3366                        _ => was_previously_expanded || all_diff_hunks_expanded,
3367                    };
3368
3369                    if should_expand_hunk {
3370                        did_expand_hunks = true;
3371                        log::trace!(
3372                            "expanding hunk {:?}, excerpt:{:?}",
3373                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3374                            excerpt.id
3375                        );
3376
3377                        if !hunk.diff_base_byte_range.is_empty()
3378                            && hunk_buffer_range.start >= edit_buffer_start
3379                            && hunk_buffer_range.start <= excerpt_buffer_end
3380                        {
3381                            let base_text = diff.base_text();
3382                            let mut text_cursor =
3383                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3384                            let mut base_text_summary =
3385                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3386
3387                            let mut has_trailing_newline = false;
3388                            if base_text_summary.last_line_chars > 0 {
3389                                base_text_summary += TextSummary::newline();
3390                                has_trailing_newline = true;
3391                            }
3392
3393                            new_diff_transforms.push(
3394                                DiffTransform::DeletedHunk {
3395                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3396                                    summary: base_text_summary,
3397                                    buffer_id: excerpt.buffer_id,
3398                                    hunk_info,
3399                                    has_trailing_newline,
3400                                },
3401                                (),
3402                            );
3403                        }
3404
3405                        if !hunk_buffer_range.is_empty() {
3406                            *end_of_current_insert =
3407                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3408                        }
3409                    }
3410                }
3411            }
3412
3413            if excerpts.end() <= edit.new.end {
3414                excerpts.next();
3415            } else {
3416                break;
3417            }
3418        }
3419
3420        did_expand_hunks || !old_expanded_hunks.is_empty()
3421    }
3422
3423    fn append_diff_transforms(
3424        &self,
3425        new_transforms: &mut SumTree<DiffTransform>,
3426        subtree: SumTree<DiffTransform>,
3427    ) {
3428        if let Some(DiffTransform::BufferContent {
3429            inserted_hunk_info,
3430            summary,
3431        }) = subtree.first()
3432            && self.extend_last_buffer_content_transform(
3433                new_transforms,
3434                *inserted_hunk_info,
3435                *summary,
3436            )
3437        {
3438            let mut cursor = subtree.cursor::<()>(());
3439            cursor.next();
3440            cursor.next();
3441            new_transforms.append(cursor.suffix(), ());
3442            return;
3443        }
3444        new_transforms.append(subtree, ());
3445    }
3446
3447    fn push_diff_transform(
3448        &self,
3449        new_transforms: &mut SumTree<DiffTransform>,
3450        transform: DiffTransform,
3451    ) {
3452        if let DiffTransform::BufferContent {
3453            inserted_hunk_info: inserted_hunk_anchor,
3454            summary,
3455        } = transform
3456            && self.extend_last_buffer_content_transform(
3457                new_transforms,
3458                inserted_hunk_anchor,
3459                summary,
3460            )
3461        {
3462            return;
3463        }
3464        new_transforms.push(transform, ());
3465    }
3466
3467    fn push_buffer_content_transform(
3468        &self,
3469        old_snapshot: &MultiBufferSnapshot,
3470        new_transforms: &mut SumTree<DiffTransform>,
3471        end_offset: ExcerptOffset,
3472        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3473    ) {
3474        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3475            (end_offset.min(insertion_end_offset), Some(hunk_info))
3476        });
3477        let unchanged_region = [(end_offset, None)];
3478
3479        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3480        {
3481            let start_offset = new_transforms.summary().excerpt_len();
3482            if end_offset <= start_offset {
3483                continue;
3484            }
3485            let summary_to_add = old_snapshot
3486                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3487
3488            if !self.extend_last_buffer_content_transform(
3489                new_transforms,
3490                inserted_hunk_info,
3491                summary_to_add,
3492            ) {
3493                new_transforms.push(
3494                    DiffTransform::BufferContent {
3495                        summary: summary_to_add,
3496                        inserted_hunk_info,
3497                    },
3498                    (),
3499                )
3500            }
3501        }
3502    }
3503
3504    fn extend_last_buffer_content_transform(
3505        &self,
3506        new_transforms: &mut SumTree<DiffTransform>,
3507        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3508        summary_to_add: TextSummary,
3509    ) -> bool {
3510        let mut did_extend = false;
3511        new_transforms.update_last(
3512            |last_transform| {
3513                if let DiffTransform::BufferContent {
3514                    summary,
3515                    inserted_hunk_info: inserted_hunk_anchor,
3516                } = last_transform
3517                    && *inserted_hunk_anchor == new_inserted_hunk_info
3518                {
3519                    *summary += summary_to_add;
3520                    did_extend = true;
3521                }
3522            },
3523            (),
3524        );
3525        did_extend
3526    }
3527}
3528
3529fn build_excerpt_ranges(
3530    ranges: impl IntoIterator<Item = Range<Point>>,
3531    context_line_count: u32,
3532    buffer_snapshot: &BufferSnapshot,
3533) -> Vec<ExcerptRange<Point>> {
3534    ranges
3535        .into_iter()
3536        .map(|range| {
3537            let start_row = range.start.row.saturating_sub(context_line_count);
3538            let start = Point::new(start_row, 0);
3539            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3540            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3541            ExcerptRange {
3542                context: start..end,
3543                primary: range,
3544            }
3545        })
3546        .collect()
3547}
3548
3549#[cfg(any(test, feature = "test-support"))]
3550impl MultiBuffer {
3551    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3552        let buffer = cx.new(|cx| Buffer::local(text, cx));
3553        cx.new(|cx| Self::singleton(buffer, cx))
3554    }
3555
3556    pub fn build_multi<const COUNT: usize>(
3557        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3558        cx: &mut gpui::App,
3559    ) -> Entity<Self> {
3560        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3561        for (text, ranges) in excerpts {
3562            let buffer = cx.new(|cx| Buffer::local(text, cx));
3563            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3564            multi.update(cx, |multi, cx| {
3565                multi.push_excerpts(buffer, excerpt_ranges, cx)
3566            });
3567        }
3568
3569        multi
3570    }
3571
3572    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3573        cx.new(|cx| Self::singleton(buffer, cx))
3574    }
3575
3576    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3577        cx.new(|cx| {
3578            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3579            let mutation_count = rng.random_range(1..=5);
3580            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3581            multibuffer
3582        })
3583    }
3584
3585    pub fn randomly_edit(
3586        &mut self,
3587        rng: &mut impl rand::Rng,
3588        edit_count: usize,
3589        cx: &mut Context<Self>,
3590    ) {
3591        use util::RandomCharIter;
3592
3593        let snapshot = self.read(cx);
3594        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3595        let mut last_end = None;
3596        for _ in 0..edit_count {
3597            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3598                break;
3599            }
3600
3601            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3602            let end =
3603                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3604            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3605            last_end = Some(end);
3606
3607            let mut range = start..end;
3608            if rng.random_bool(0.2) {
3609                mem::swap(&mut range.start, &mut range.end);
3610            }
3611
3612            let new_text_len = rng.random_range(0..10);
3613            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3614
3615            edits.push((range, new_text.into()));
3616        }
3617        log::info!("mutating multi-buffer with {:?}", edits);
3618        drop(snapshot);
3619
3620        self.edit(edits, None, cx);
3621    }
3622
3623    pub fn randomly_edit_excerpts(
3624        &mut self,
3625        rng: &mut impl rand::Rng,
3626        mutation_count: usize,
3627        cx: &mut Context<Self>,
3628    ) {
3629        use rand::prelude::*;
3630        use std::env;
3631        use util::RandomCharIter;
3632
3633        let max_excerpts = env::var("MAX_EXCERPTS")
3634            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3635            .unwrap_or(5);
3636
3637        let mut buffers = Vec::new();
3638        for _ in 0..mutation_count {
3639            if rng.random_bool(0.05) {
3640                log::info!("Clearing multi-buffer");
3641                self.clear(cx);
3642                continue;
3643            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3644                let ids = self.excerpt_ids();
3645                let mut excerpts = HashSet::default();
3646                for _ in 0..rng.random_range(0..ids.len()) {
3647                    excerpts.extend(ids.choose(rng).copied());
3648                }
3649
3650                let line_count = rng.random_range(0..5);
3651
3652                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3653
3654                self.expand_excerpts(
3655                    excerpts.iter().cloned(),
3656                    line_count,
3657                    ExpandExcerptDirection::UpAndDown,
3658                    cx,
3659                );
3660                continue;
3661            }
3662
3663            let excerpt_ids = self.excerpt_ids();
3664            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3665                let buffer_handle = if rng.random() || self.buffers.borrow().is_empty() {
3666                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3667                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3668                    let buffer = buffers.last().unwrap().read(cx);
3669                    log::info!(
3670                        "Creating new buffer {} with text: {:?}",
3671                        buffer.remote_id(),
3672                        buffer.text()
3673                    );
3674                    buffers.last().unwrap().clone()
3675                } else {
3676                    self.buffers
3677                        .borrow()
3678                        .values()
3679                        .choose(rng)
3680                        .unwrap()
3681                        .buffer
3682                        .clone()
3683                };
3684
3685                let buffer = buffer_handle.read(cx);
3686                let buffer_text = buffer.text();
3687                let ranges = (0..rng.random_range(0..5))
3688                    .map(|_| {
3689                        let end_ix =
3690                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3691                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3692                        ExcerptRange::new(start_ix..end_ix)
3693                    })
3694                    .collect::<Vec<_>>();
3695                log::info!(
3696                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3697                    buffer_handle.read(cx).remote_id(),
3698                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3699                    ranges
3700                        .iter()
3701                        .map(|r| &buffer_text[r.context.clone()])
3702                        .collect::<Vec<_>>()
3703                );
3704
3705                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3706                log::info!("Inserted with ids: {:?}", excerpt_id);
3707            } else {
3708                let remove_count = rng.random_range(1..=excerpt_ids.len());
3709                let mut excerpts_to_remove = excerpt_ids
3710                    .choose_multiple(rng, remove_count)
3711                    .cloned()
3712                    .collect::<Vec<_>>();
3713                let snapshot = self.snapshot.borrow();
3714                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3715                drop(snapshot);
3716                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3717                self.remove_excerpts(excerpts_to_remove, cx);
3718            }
3719        }
3720    }
3721
3722    pub fn randomly_mutate(
3723        &mut self,
3724        rng: &mut impl rand::Rng,
3725        mutation_count: usize,
3726        cx: &mut Context<Self>,
3727    ) {
3728        use rand::prelude::*;
3729
3730        if rng.random_bool(0.7) || self.singleton {
3731            let buffer = self
3732                .buffers
3733                .borrow()
3734                .values()
3735                .choose(rng)
3736                .map(|state| state.buffer.clone());
3737
3738            if let Some(buffer) = buffer {
3739                buffer.update(cx, |buffer, cx| {
3740                    if rng.random() {
3741                        buffer.randomly_edit(rng, mutation_count, cx);
3742                    } else {
3743                        buffer.randomly_undo_redo(rng, cx);
3744                    }
3745                });
3746            } else {
3747                self.randomly_edit(rng, mutation_count, cx);
3748            }
3749        } else {
3750            self.randomly_edit_excerpts(rng, mutation_count, cx);
3751        }
3752
3753        self.check_invariants(cx);
3754    }
3755
3756    fn check_invariants(&self, cx: &App) {
3757        self.read(cx).check_invariants();
3758    }
3759}
3760
3761impl EventEmitter<Event> for MultiBuffer {}
3762
3763impl MultiBufferSnapshot {
3764    pub fn text(&self) -> String {
3765        self.chunks(0..self.len(), false)
3766            .map(|chunk| chunk.text)
3767            .collect()
3768    }
3769
3770    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3771        self.reversed_chunks_in_range(0..position.to_offset(self))
3772            .flat_map(|c| c.chars().rev())
3773    }
3774
3775    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3776        let mut cursor = self.cursor::<usize>();
3777        cursor.seek(&range.end);
3778        let current_chunks = cursor.region().as_ref().map(|region| {
3779            let start_overshoot = range.start.saturating_sub(region.range.start);
3780            let end_overshoot = range.end - region.range.start;
3781            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3782            let start = region.buffer_range.start + start_overshoot;
3783            region.buffer.reversed_chunks_in_range(start..end)
3784        });
3785        ReversedMultiBufferChunks {
3786            cursor,
3787            current_chunks,
3788            start: range.start,
3789            offset: range.end,
3790        }
3791    }
3792
3793    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3794        let offset = position.to_offset(self);
3795        self.text_for_range(offset..self.len())
3796            .flat_map(|chunk| chunk.chars())
3797    }
3798
3799    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3800        self.chunks(range, false).map(|chunk| chunk.text)
3801    }
3802
3803    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3804        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3805            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3806    }
3807
3808    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3809    where
3810        T: ToOffset,
3811    {
3812        let position = position.to_offset(self);
3813        position == self.clip_offset(position, Bias::Left)
3814            && self
3815                .bytes_in_range(position..self.len())
3816                .flatten()
3817                .copied()
3818                .take(needle.len())
3819                .eq(needle.bytes())
3820    }
3821
3822    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3823        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3824    }
3825
3826    pub fn diff_hunks_in_range<T: ToPoint>(
3827        &self,
3828        range: Range<T>,
3829    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3830        let query_range = range.start.to_point(self)..range.end.to_point(self);
3831        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3832            let diff = self.diffs.get(&buffer.remote_id())?;
3833            let buffer_start = buffer.anchor_before(buffer_range.start);
3834            let buffer_end = buffer.anchor_after(buffer_range.end);
3835            Some(
3836                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3837                    .filter_map(|hunk| {
3838                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3839                            return None;
3840                        }
3841                        Some((hunk.range.clone(), hunk))
3842                    }),
3843            )
3844        })
3845        .filter_map(move |(range, hunk, excerpt)| {
3846            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3847            {
3848                return None;
3849            }
3850            let end_row = if range.end.column == 0 {
3851                range.end.row
3852            } else {
3853                range.end.row + 1
3854            };
3855            Some(MultiBufferDiffHunk {
3856                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3857                buffer_id: excerpt.buffer_id,
3858                excerpt_id: excerpt.id,
3859                buffer_range: hunk.buffer_range.clone(),
3860                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3861                secondary_status: hunk.secondary_status,
3862            })
3863        })
3864    }
3865
3866    pub fn excerpt_ids_for_range<T: ToOffset>(
3867        &self,
3868        range: Range<T>,
3869    ) -> impl Iterator<Item = ExcerptId> + '_ {
3870        let range = range.start.to_offset(self)..range.end.to_offset(self);
3871        let mut cursor = self.cursor::<usize>();
3872        cursor.seek(&range.start);
3873        std::iter::from_fn(move || {
3874            let region = cursor.region()?;
3875            if region.range.start >= range.end {
3876                return None;
3877            }
3878            cursor.next_excerpt();
3879            Some(region.excerpt.id)
3880        })
3881    }
3882
3883    pub fn buffer_ids_for_range<T: ToOffset>(
3884        &self,
3885        range: Range<T>,
3886    ) -> impl Iterator<Item = BufferId> + '_ {
3887        let range = range.start.to_offset(self)..range.end.to_offset(self);
3888        let mut cursor = self.cursor::<usize>();
3889        cursor.seek(&range.start);
3890        std::iter::from_fn(move || {
3891            let region = cursor.region()?;
3892            if region.range.start > range.end
3893                || region.range.start == range.end && region.range.start > range.start
3894            {
3895                return None;
3896            }
3897            cursor.next_excerpt();
3898            Some(region.excerpt.buffer_id)
3899        })
3900    }
3901
3902    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3903        &self,
3904        ranges: impl Iterator<Item = Range<T>>,
3905    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3906        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3907    }
3908
3909    pub fn range_to_buffer_ranges<T: ToOffset>(
3910        &self,
3911        range: Range<T>,
3912    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3913        let start = range.start.to_offset(self);
3914        let end = range.end.to_offset(self);
3915
3916        let mut cursor = self.cursor::<usize>();
3917        cursor.seek(&start);
3918
3919        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3920        while let Some(region) = cursor.region() {
3921            if region.range.start > end {
3922                break;
3923            }
3924            if region.is_main_buffer {
3925                let start_overshoot = start.saturating_sub(region.range.start);
3926                let end_overshoot = end.saturating_sub(region.range.start);
3927                let start = region
3928                    .buffer_range
3929                    .end
3930                    .min(region.buffer_range.start + start_overshoot);
3931                let end = region
3932                    .buffer_range
3933                    .end
3934                    .min(region.buffer_range.start + end_overshoot);
3935                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3936                    *excerpt_id == region.excerpt.id && prev_range.end == start
3937                }) {
3938                    prev.1.end = end;
3939                } else {
3940                    result.push((region.buffer, start..end, region.excerpt.id));
3941                }
3942            }
3943            cursor.next();
3944        }
3945        result
3946    }
3947
3948    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3949        &self,
3950        range: Range<T>,
3951    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3952        let start = range.start.to_offset(self);
3953        let end = range.end.to_offset(self);
3954
3955        let mut cursor = self.cursor::<usize>();
3956        cursor.seek(&start);
3957
3958        std::iter::from_fn(move || {
3959            let region = cursor.region()?;
3960            if region.range.start > end {
3961                return None;
3962            }
3963            let start_overshoot = start.saturating_sub(region.range.start);
3964            let end_overshoot = end.saturating_sub(region.range.start);
3965            let start = region
3966                .buffer_range
3967                .end
3968                .min(region.buffer_range.start + start_overshoot);
3969            let end = region
3970                .buffer_range
3971                .end
3972                .min(region.buffer_range.start + end_overshoot);
3973
3974            let region_excerpt_id = region.excerpt.id;
3975            let deleted_hunk_anchor = if region.is_main_buffer {
3976                None
3977            } else {
3978                Some(self.anchor_before(region.range.start))
3979            };
3980            let result = (
3981                region.buffer,
3982                start..end,
3983                region_excerpt_id,
3984                deleted_hunk_anchor,
3985            );
3986            cursor.next();
3987            Some(result)
3988        })
3989    }
3990
3991    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3992    /// coordinates.
3993    ///
3994    /// The given callback will be called for every excerpt intersecting the given range. It will
3995    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3996    /// The callback should return an iterator of metadata items from that buffer, each paired
3997    /// with a buffer range.
3998    ///
3999    /// The returned iterator yields each of these metadata items, paired with its range in
4000    /// multi-buffer coordinates.
4001    fn lift_buffer_metadata<'a, D, M, I>(
4002        &'a self,
4003        query_range: Range<D>,
4004        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
4005    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
4006    where
4007        I: Iterator<Item = (Range<D>, M)> + 'a,
4008        D: TextDimension + Ord + Sub<D, Output = D>,
4009    {
4010        let max_position = D::from_text_summary(&self.text_summary());
4011        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4012        let mut cursor = self.cursor::<D>();
4013
4014        // Find the excerpt and buffer offset where the given range ends.
4015        cursor.seek(&query_range.end);
4016        let mut range_end = None;
4017        while let Some(region) = cursor.region() {
4018            if region.is_main_buffer {
4019                let mut buffer_end = region.buffer_range.start;
4020                let overshoot = if query_range.end > region.range.start {
4021                    query_range.end - region.range.start
4022                } else {
4023                    D::default()
4024                };
4025                buffer_end.add_assign(&overshoot);
4026                range_end = Some((region.excerpt.id, buffer_end));
4027                break;
4028            }
4029            cursor.next();
4030        }
4031
4032        cursor.seek(&query_range.start);
4033
4034        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4035            && region.range.start > D::zero(())
4036        {
4037            cursor.prev()
4038        }
4039
4040        iter::from_fn(move || {
4041            loop {
4042                let excerpt = cursor.excerpt()?;
4043
4044                // If we have already retrieved metadata for this excerpt, continue to use it.
4045                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4046                    .as_mut()
4047                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4048                {
4049                    Some(metadata)
4050                }
4051                // Otherwise, compute the intersection of the input range with the excerpt's range,
4052                // and retrieve the metadata for the resulting range.
4053                else {
4054                    let region = cursor.region()?;
4055                    let mut buffer_start;
4056                    if region.is_main_buffer {
4057                        buffer_start = region.buffer_range.start;
4058                        if query_range.start > region.range.start {
4059                            let overshoot = query_range.start - region.range.start;
4060                            buffer_start.add_assign(&overshoot);
4061                        }
4062                        buffer_start = buffer_start.min(region.buffer_range.end);
4063                    } else {
4064                        buffer_start = cursor.main_buffer_position()?;
4065                    };
4066                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4067                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4068                        && excerpt.id == end_excerpt_id
4069                    {
4070                        buffer_end = buffer_end.min(end_buffer_offset);
4071                    }
4072
4073                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4074                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4075                    })
4076                };
4077
4078                // Visit each metadata item.
4079                if let Some((metadata_buffer_range, metadata)) =
4080                    metadata_iter.and_then(Iterator::next)
4081                {
4082                    // Find the multibuffer regions that contain the start and end of
4083                    // the metadata item's range.
4084                    if metadata_buffer_range.start > D::default() {
4085                        while let Some(region) = cursor.region() {
4086                            if region.is_main_buffer
4087                                && (region.buffer_range.end >= metadata_buffer_range.start
4088                                    || cursor.is_at_end_of_excerpt())
4089                            {
4090                                break;
4091                            }
4092                            cursor.next();
4093                        }
4094                    }
4095                    let start_region = cursor.region()?;
4096                    while let Some(region) = cursor.region() {
4097                        if region.is_main_buffer
4098                            && (region.buffer_range.end > metadata_buffer_range.end
4099                                || cursor.is_at_end_of_excerpt())
4100                        {
4101                            break;
4102                        }
4103                        cursor.next();
4104                    }
4105                    let end_region = cursor.region();
4106
4107                    // Convert the metadata item's range into multibuffer coordinates.
4108                    let mut start_position = start_region.range.start;
4109                    let region_buffer_start = start_region.buffer_range.start;
4110                    if start_region.is_main_buffer
4111                        && metadata_buffer_range.start > region_buffer_start
4112                    {
4113                        start_position
4114                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4115                        start_position = start_position.min(start_region.range.end);
4116                    }
4117
4118                    let mut end_position = max_position;
4119                    if let Some(end_region) = &end_region {
4120                        end_position = end_region.range.start;
4121                        debug_assert!(end_region.is_main_buffer);
4122                        let region_buffer_start = end_region.buffer_range.start;
4123                        if metadata_buffer_range.end > region_buffer_start {
4124                            end_position
4125                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4126                        }
4127                        end_position = end_position.min(end_region.range.end);
4128                    }
4129
4130                    if start_position <= query_range.end && end_position >= query_range.start {
4131                        return Some((start_position..end_position, metadata, excerpt));
4132                    }
4133                }
4134                // When there are no more metadata items for this excerpt, move to the next excerpt.
4135                else {
4136                    current_excerpt_metadata.take();
4137                    if let Some((end_excerpt_id, _)) = range_end
4138                        && excerpt.id == end_excerpt_id
4139                    {
4140                        return None;
4141                    }
4142                    cursor.next_excerpt();
4143                }
4144            }
4145        })
4146    }
4147
4148    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4149        let offset = position.to_offset(self);
4150
4151        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4152        cursor.seek(&DimensionPair {
4153            key: offset,
4154            value: None,
4155        });
4156        cursor.seek_to_start_of_current_excerpt();
4157        let excerpt = cursor.excerpt()?;
4158
4159        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4160        let current_position = self
4161            .anchor_before(offset)
4162            .text_anchor
4163            .to_offset(&excerpt.buffer);
4164        let excerpt_end = excerpt
4165            .buffer
4166            .anchor_before(excerpt_end.min(current_position));
4167
4168        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4169            for hunk in diff.hunks_intersecting_range_rev(
4170                excerpt.range.context.start..excerpt_end,
4171                &excerpt.buffer,
4172            ) {
4173                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4174                if hunk_end >= current_position {
4175                    continue;
4176                }
4177                let start =
4178                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4179                        .to_point(self);
4180                return Some(MultiBufferRow(start.row));
4181            }
4182        }
4183
4184        loop {
4185            cursor.prev_excerpt();
4186            let excerpt = cursor.excerpt()?;
4187
4188            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4189                continue;
4190            };
4191            let mut hunks =
4192                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4193            let Some(hunk) = hunks.next() else {
4194                continue;
4195            };
4196            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4197                .to_point(self);
4198            return Some(MultiBufferRow(start.row));
4199        }
4200    }
4201
4202    pub fn has_diff_hunks(&self) -> bool {
4203        self.diffs.values().any(|diff| !diff.is_empty())
4204    }
4205
4206    pub fn is_inside_word<T: ToOffset>(
4207        &self,
4208        position: T,
4209        scope_context: Option<CharScopeContext>,
4210    ) -> bool {
4211        let position = position.to_offset(self);
4212        let classifier = self
4213            .char_classifier_at(position)
4214            .scope_context(scope_context);
4215        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4216        let prev_char_kind = self
4217            .reversed_chars_at(position)
4218            .next()
4219            .map(|c| classifier.kind(c));
4220        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4221    }
4222
4223    pub fn surrounding_word<T: ToOffset>(
4224        &self,
4225        start: T,
4226        scope_context: Option<CharScopeContext>,
4227    ) -> (Range<usize>, Option<CharKind>) {
4228        let mut start = start.to_offset(self);
4229        let mut end = start;
4230        let mut next_chars = self.chars_at(start).peekable();
4231        let mut prev_chars = self.reversed_chars_at(start).peekable();
4232
4233        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4234
4235        let word_kind = cmp::max(
4236            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4237            next_chars.peek().copied().map(|c| classifier.kind(c)),
4238        );
4239
4240        for ch in prev_chars {
4241            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4242                start -= ch.len_utf8();
4243            } else {
4244                break;
4245            }
4246        }
4247
4248        for ch in next_chars {
4249            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4250                end += ch.len_utf8();
4251            } else {
4252                break;
4253            }
4254        }
4255
4256        (start..end, word_kind)
4257    }
4258
4259    pub fn char_kind_before<T: ToOffset>(
4260        &self,
4261        start: T,
4262        scope_context: Option<CharScopeContext>,
4263    ) -> Option<CharKind> {
4264        let start = start.to_offset(self);
4265        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4266        self.reversed_chars_at(start)
4267            .next()
4268            .map(|ch| classifier.kind(ch))
4269    }
4270
4271    pub fn is_singleton(&self) -> bool {
4272        self.singleton
4273    }
4274
4275    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4276        if self.singleton {
4277            self.excerpts
4278                .iter()
4279                .next()
4280                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4281        } else {
4282            None
4283        }
4284    }
4285
4286    pub fn len(&self) -> usize {
4287        self.diff_transforms.summary().output.len
4288    }
4289
4290    pub fn is_empty(&self) -> bool {
4291        self.excerpts.summary().text.len == 0
4292    }
4293
4294    pub fn widest_line_number(&self) -> u32 {
4295        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4296        self.excerpts.summary().widest_line_number + 1
4297    }
4298
4299    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4300        let range = range.start.to_offset(self)..range.end.to_offset(self);
4301        let mut excerpts = self.cursor::<usize>();
4302        excerpts.seek(&range.start);
4303
4304        let mut chunk;
4305        let mut has_trailing_newline;
4306        let excerpt_bytes;
4307        if let Some(region) = excerpts.region() {
4308            let mut bytes = region.buffer.bytes_in_range(
4309                region.buffer_range.start + range.start - region.range.start
4310                    ..(region.buffer_range.start + range.end - region.range.start)
4311                        .min(region.buffer_range.end),
4312            );
4313            chunk = bytes.next().unwrap_or(&[][..]);
4314            excerpt_bytes = Some(bytes);
4315            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4316            if chunk.is_empty() && has_trailing_newline {
4317                chunk = b"\n";
4318                has_trailing_newline = false;
4319            }
4320        } else {
4321            chunk = &[][..];
4322            excerpt_bytes = None;
4323            has_trailing_newline = false;
4324        };
4325
4326        MultiBufferBytes {
4327            range,
4328            cursor: excerpts,
4329            excerpt_bytes,
4330            has_trailing_newline,
4331            chunk,
4332        }
4333    }
4334
4335    pub fn reversed_bytes_in_range<T: ToOffset>(
4336        &self,
4337        range: Range<T>,
4338    ) -> ReversedMultiBufferBytes<'_> {
4339        let range = range.start.to_offset(self)..range.end.to_offset(self);
4340        let mut chunks = self.reversed_chunks_in_range(range.clone());
4341        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4342        ReversedMultiBufferBytes {
4343            range,
4344            chunks,
4345            chunk,
4346        }
4347    }
4348
4349    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4350        let mut cursor = self.cursor::<Point>();
4351        cursor.seek(&Point::new(start_row.0, 0));
4352        let mut result = MultiBufferRows {
4353            point: Point::new(0, 0),
4354            is_empty: self.excerpts.is_empty(),
4355            is_singleton: self.is_singleton(),
4356            cursor,
4357        };
4358        result.seek(start_row);
4359        result
4360    }
4361
4362    pub fn chunks<T: ToOffset>(
4363        &self,
4364        range: Range<T>,
4365        language_aware: bool,
4366    ) -> MultiBufferChunks<'_> {
4367        let mut chunks = MultiBufferChunks {
4368            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4369            range: 0..0,
4370            excerpts: self.excerpts.cursor(()),
4371            diff_transforms: self.diff_transforms.cursor(()),
4372            diffs: &self.diffs,
4373            diff_base_chunks: None,
4374            excerpt_chunks: None,
4375            buffer_chunk: None,
4376            language_aware,
4377        };
4378        let range = range.start.to_offset(self)..range.end.to_offset(self);
4379        chunks.seek(range);
4380        chunks
4381    }
4382
4383    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4384        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4385    }
4386
4387    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4388        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4389    }
4390
4391    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4392        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4393    }
4394
4395    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4396        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4397            buffer.clip_point_utf16(Unclipped(point), bias)
4398        })
4399    }
4400
4401    pub fn offset_to_point(&self, offset: usize) -> Point {
4402        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4403    }
4404
4405    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4406        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4407    }
4408
4409    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4410        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4411    }
4412
4413    pub fn point_to_offset(&self, point: Point) -> usize {
4414        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4415    }
4416
4417    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4418        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4419    }
4420
4421    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4422        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4423    }
4424
4425    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4426        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4427    }
4428
4429    fn clip_dimension<D>(
4430        &self,
4431        position: D,
4432        bias: Bias,
4433        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4434    ) -> D
4435    where
4436        D: TextDimension + Ord + Sub<D, Output = D>,
4437    {
4438        let mut cursor = self.cursor();
4439        cursor.seek(&position);
4440        if let Some(region) = cursor.region() {
4441            if position >= region.range.end {
4442                return region.range.end;
4443            }
4444            let overshoot = position - region.range.start;
4445            let mut buffer_position = region.buffer_range.start;
4446            buffer_position.add_assign(&overshoot);
4447            let clipped_buffer_position =
4448                clip_buffer_position(region.buffer, buffer_position, bias);
4449            let mut position = region.range.start;
4450            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4451            position
4452        } else {
4453            D::from_text_summary(&self.text_summary())
4454        }
4455    }
4456
4457    fn convert_dimension<D1, D2>(
4458        &self,
4459        key: D1,
4460        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4461    ) -> D2
4462    where
4463        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4464        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4465    {
4466        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4467        cursor.seek(&DimensionPair { key, value: None });
4468        if let Some(region) = cursor.region() {
4469            if key >= region.range.end.key {
4470                return region.range.end.value.unwrap();
4471            }
4472            let start_key = region.range.start.key;
4473            let start_value = region.range.start.value.unwrap();
4474            let buffer_start_key = region.buffer_range.start.key;
4475            let buffer_start_value = region.buffer_range.start.value.unwrap();
4476            let mut buffer_key = buffer_start_key;
4477            buffer_key.add_assign(&(key - start_key));
4478            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4479            let mut result = start_value;
4480            result.add_assign(&(buffer_value - buffer_start_value));
4481            result
4482        } else {
4483            D2::from_text_summary(&self.text_summary())
4484        }
4485    }
4486
4487    pub fn point_to_buffer_offset<T: ToOffset>(
4488        &self,
4489        point: T,
4490    ) -> Option<(&BufferSnapshot, usize)> {
4491        let offset = point.to_offset(self);
4492        let mut cursor = self.cursor::<usize>();
4493        cursor.seek(&offset);
4494        let region = cursor.region()?;
4495        let overshoot = offset - region.range.start;
4496        let buffer_offset = region.buffer_range.start + overshoot;
4497        if buffer_offset == region.buffer.len() + 1
4498            && region.has_trailing_newline
4499            && !region.is_main_buffer
4500        {
4501            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4502        } else if buffer_offset > region.buffer.len() {
4503            return None;
4504        }
4505        Some((region.buffer, buffer_offset))
4506    }
4507
4508    pub fn point_to_buffer_point(
4509        &self,
4510        point: Point,
4511    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4512        let mut cursor = self.cursor::<Point>();
4513        cursor.seek(&point);
4514        let region = cursor.region()?;
4515        let overshoot = point - region.range.start;
4516        let buffer_point = region.buffer_range.start + overshoot;
4517        let excerpt = cursor.excerpt()?;
4518        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4519            && region.has_trailing_newline
4520            && !region.is_main_buffer
4521        {
4522            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4523        } else if buffer_point > region.buffer.max_point() {
4524            return None;
4525        }
4526        Some((region.buffer, buffer_point, excerpt.id))
4527    }
4528
4529    pub fn suggested_indents(
4530        &self,
4531        rows: impl IntoIterator<Item = u32>,
4532        cx: &App,
4533    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4534        let mut result = BTreeMap::new();
4535
4536        let mut rows_for_excerpt = Vec::new();
4537        let mut cursor = self.cursor::<Point>();
4538        let mut rows = rows.into_iter().peekable();
4539        let mut prev_row = u32::MAX;
4540        let mut prev_language_indent_size = IndentSize::default();
4541
4542        while let Some(row) = rows.next() {
4543            cursor.seek(&Point::new(row, 0));
4544            let Some(region) = cursor.region() else {
4545                continue;
4546            };
4547
4548            // Retrieve the language and indent size once for each disjoint region being indented.
4549            let single_indent_size = if row.saturating_sub(1) == prev_row {
4550                prev_language_indent_size
4551            } else {
4552                region
4553                    .buffer
4554                    .language_indent_size_at(Point::new(row, 0), cx)
4555            };
4556            prev_language_indent_size = single_indent_size;
4557            prev_row = row;
4558
4559            let start_buffer_row = region.buffer_range.start.row;
4560            let start_multibuffer_row = region.range.start.row;
4561            let end_multibuffer_row = region.range.end.row;
4562
4563            rows_for_excerpt.push(row);
4564            while let Some(next_row) = rows.peek().copied() {
4565                if end_multibuffer_row > next_row {
4566                    rows_for_excerpt.push(next_row);
4567                    rows.next();
4568                } else {
4569                    break;
4570                }
4571            }
4572
4573            let buffer_rows = rows_for_excerpt
4574                .drain(..)
4575                .map(|row| start_buffer_row + row - start_multibuffer_row);
4576            let buffer_indents = region
4577                .buffer
4578                .suggested_indents(buffer_rows, single_indent_size);
4579            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4580                (
4581                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4582                    indent,
4583                )
4584            });
4585            result.extend(multibuffer_indents);
4586        }
4587
4588        result
4589    }
4590
4591    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4592        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4593            let mut size = buffer.indent_size_for_line(range.start.row);
4594            size.len = size
4595                .len
4596                .min(range.end.column)
4597                .saturating_sub(range.start.column);
4598            size
4599        } else {
4600            IndentSize::spaces(0)
4601        }
4602    }
4603
4604    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4605        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4606            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4607        } else {
4608            LineIndent::spaces(0)
4609        }
4610    }
4611
4612    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4613        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4614
4615        if self.language_settings(cx).extend_comment_on_newline
4616            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4617        {
4618            let delimiters = language_scope.line_comment_prefixes();
4619            for delimiter in delimiters {
4620                if *self
4621                    .chars_at(Point::new(row.0, indent.len() as u32))
4622                    .take(delimiter.chars().count())
4623                    .collect::<String>()
4624                    .as_str()
4625                    == **delimiter
4626                {
4627                    indent.push_str(delimiter);
4628                    break;
4629                }
4630            }
4631        }
4632
4633        indent
4634    }
4635
4636    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4637    where
4638        T: ToOffset,
4639    {
4640        for char in self.reversed_chars_at(position) {
4641            if !char.is_whitespace() {
4642                return false;
4643            }
4644            if char == '\n' {
4645                return true;
4646            }
4647        }
4648        true
4649    }
4650
4651    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4652        while row.0 > 0 {
4653            row.0 -= 1;
4654            if !self.is_line_blank(row) {
4655                return Some(row);
4656            }
4657        }
4658        None
4659    }
4660
4661    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4662        if let Some((_, range)) = self.buffer_line_for_row(row) {
4663            range.end.column - range.start.column
4664        } else {
4665            0
4666        }
4667    }
4668
4669    pub fn buffer_line_for_row(
4670        &self,
4671        row: MultiBufferRow,
4672    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4673        let mut cursor = self.cursor::<Point>();
4674        let point = Point::new(row.0, 0);
4675        cursor.seek(&point);
4676        let region = cursor.region()?;
4677        let overshoot = point.min(region.range.end) - region.range.start;
4678        let buffer_point = region.buffer_range.start + overshoot;
4679        if buffer_point.row > region.buffer_range.end.row {
4680            return None;
4681        }
4682        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4683        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4684            .min(region.buffer_range.end);
4685        Some((region.buffer, line_start..line_end))
4686    }
4687
4688    pub fn max_point(&self) -> Point {
4689        self.text_summary().lines
4690    }
4691
4692    pub fn max_row(&self) -> MultiBufferRow {
4693        MultiBufferRow(self.text_summary().lines.row)
4694    }
4695
4696    pub fn text_summary(&self) -> TextSummary {
4697        self.diff_transforms.summary().output
4698    }
4699
4700    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4701    where
4702        D: TextDimension,
4703        O: ToOffset,
4704    {
4705        let range = range.start.to_offset(self)..range.end.to_offset(self);
4706        let mut cursor = self
4707            .diff_transforms
4708            .cursor::<Dimensions<usize, ExcerptOffset>>(());
4709        cursor.seek(&range.start, Bias::Right);
4710
4711        let Some(first_transform) = cursor.item() else {
4712            return D::from_text_summary(&TextSummary::default());
4713        };
4714
4715        let diff_transform_start = cursor.start().0;
4716        let diff_transform_end = cursor.end().0;
4717        let diff_start = range.start;
4718        let start_overshoot = diff_start - diff_transform_start;
4719        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4720
4721        let mut result = match first_transform {
4722            DiffTransform::BufferContent { .. } => {
4723                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4724                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4725                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4726            }
4727            DiffTransform::DeletedHunk {
4728                buffer_id,
4729                base_text_byte_range,
4730                has_trailing_newline,
4731                ..
4732            } => {
4733                let buffer_start = base_text_byte_range.start + start_overshoot;
4734                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4735                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4736                    panic!("{:?} is in non-existent deleted hunk", range.start)
4737                };
4738
4739                let include_trailing_newline =
4740                    *has_trailing_newline && range.end >= diff_transform_end;
4741                if include_trailing_newline {
4742                    buffer_end -= 1;
4743                }
4744
4745                let mut summary =
4746                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4747
4748                if include_trailing_newline {
4749                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4750                }
4751
4752                summary
4753            }
4754        };
4755        if range.end < diff_transform_end {
4756            return result;
4757        }
4758
4759        cursor.next();
4760        result.add_assign(&D::from_text_summary(
4761            &cursor.summary(&range.end, Bias::Right),
4762        ));
4763
4764        let Some(last_transform) = cursor.item() else {
4765            return result;
4766        };
4767
4768        let overshoot = range.end - cursor.start().0;
4769        let suffix = match last_transform {
4770            DiffTransform::BufferContent { .. } => {
4771                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4772                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4773            }
4774            DiffTransform::DeletedHunk {
4775                base_text_byte_range,
4776                buffer_id,
4777                has_trailing_newline,
4778                ..
4779            } => {
4780                let buffer_end = base_text_byte_range.start + overshoot;
4781                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4782                    panic!("{:?} is in non-existent deleted hunk", range.end)
4783                };
4784
4785                let mut suffix = base_text
4786                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4787                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4788                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4789                }
4790                suffix
4791            }
4792        };
4793
4794        result.add_assign(&suffix);
4795        result
4796    }
4797
4798    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4799    where
4800        D: TextDimension,
4801    {
4802        // let mut range = range.start..range.end;
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() {
4927            cursor.next();
4928        }
4929
4930        let mut position = cursor.start().1;
4931        if let Some(excerpt) = cursor.item()
4932            && excerpt.id == anchor.excerpt_id
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            let excerpt_anchors = iter::from_fn(|| {
4972                let anchor = anchors.peek()?;
4973                if self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id {
4974                    Some(anchors.next().unwrap())
4975                } else {
4976                    None
4977                }
4978            });
4979
4980            let locator = self.excerpt_locator_for_id(excerpt_id);
4981            cursor.seek_forward(locator, Bias::Left);
4982            if cursor.item().is_none() {
4983                cursor.next();
4984            }
4985
4986            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4987            if let Some(excerpt) = cursor.item() {
4988                if excerpt.id != excerpt_id {
4989                    let position = self.resolve_summary_for_anchor(
4990                        &Anchor::min(),
4991                        excerpt_start_position,
4992                        &mut diff_transforms_cursor,
4993                    );
4994                    summaries.extend(excerpt_anchors.map(|_| position));
4995                    continue;
4996                }
4997                let excerpt_buffer_start =
4998                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4999                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
5000                for (buffer_summary, anchor) in excerpt
5001                    .buffer
5002                    .summaries_for_anchors_with_payload::<D, _, _>(
5003                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
5004                    )
5005                {
5006                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5007                    let mut position = excerpt_start_position;
5008                    if summary > excerpt_buffer_start {
5009                        position.add_assign(&(summary - excerpt_buffer_start));
5010                    }
5011
5012                    if position > diff_transforms_cursor.start().0.0 {
5013                        diff_transforms_cursor
5014                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5015                    }
5016
5017                    summaries.push(self.resolve_summary_for_anchor(
5018                        anchor,
5019                        position,
5020                        &mut diff_transforms_cursor,
5021                    ));
5022                }
5023            } else {
5024                diff_transforms_cursor
5025                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5026                let position = self.resolve_summary_for_anchor(
5027                    &Anchor::max(),
5028                    excerpt_start_position,
5029                    &mut diff_transforms_cursor,
5030                );
5031                summaries.extend(excerpt_anchors.map(|_| position));
5032            }
5033        }
5034
5035        summaries
5036    }
5037
5038    pub fn dimensions_from_points<'a, D>(
5039        &'a self,
5040        points: impl 'a + IntoIterator<Item = Point>,
5041    ) -> impl 'a + Iterator<Item = D>
5042    where
5043        D: TextDimension + Sub<D, Output = D>,
5044    {
5045        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5046        cursor.seek(&DimensionPair {
5047            key: Point::default(),
5048            value: None,
5049        });
5050        let mut points = points.into_iter();
5051        iter::from_fn(move || {
5052            let point = points.next()?;
5053
5054            cursor.seek_forward(&DimensionPair {
5055                key: point,
5056                value: None,
5057            });
5058
5059            if let Some(region) = cursor.region() {
5060                let overshoot = point - region.range.start.key;
5061                let buffer_point = region.buffer_range.start.key + overshoot;
5062                let mut position = region.range.start.value.unwrap();
5063                position.add_assign(
5064                    &region
5065                        .buffer
5066                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5067                );
5068                if point == region.range.end.key && region.has_trailing_newline {
5069                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5070                }
5071                Some(position)
5072            } else {
5073                Some(D::from_text_summary(&self.text_summary()))
5074            }
5075        })
5076    }
5077
5078    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5079    where
5080        I: 'a + IntoIterator<Item = &'a Anchor>,
5081    {
5082        let mut anchors = anchors.into_iter().enumerate().peekable();
5083        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5084        cursor.next();
5085
5086        let mut result = Vec::new();
5087
5088        while let Some((_, anchor)) = anchors.peek() {
5089            let old_excerpt_id = anchor.excerpt_id;
5090
5091            // Find the location where this anchor's excerpt should be.
5092            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5093            cursor.seek_forward(&Some(old_locator), Bias::Left);
5094
5095            if cursor.item().is_none() {
5096                cursor.next();
5097            }
5098
5099            let next_excerpt = cursor.item();
5100            let prev_excerpt = cursor.prev_item();
5101
5102            // Process all of the anchors for this excerpt.
5103            while let Some((_, anchor)) = anchors.peek() {
5104                if anchor.excerpt_id != old_excerpt_id {
5105                    break;
5106                }
5107                let (anchor_ix, anchor) = anchors.next().unwrap();
5108                let mut anchor = *anchor;
5109
5110                // Leave min and max anchors unchanged if invalid or
5111                // if the old excerpt still exists at this location
5112                let mut kept_position = next_excerpt
5113                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5114                    || old_excerpt_id == ExcerptId::max()
5115                    || old_excerpt_id == ExcerptId::min();
5116
5117                // If the old excerpt no longer exists at this location, then attempt to
5118                // find an equivalent position for this anchor in an adjacent excerpt.
5119                if !kept_position {
5120                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5121                        if excerpt.contains(&anchor) {
5122                            anchor.excerpt_id = excerpt.id;
5123                            kept_position = true;
5124                            break;
5125                        }
5126                    }
5127                }
5128
5129                // If there's no adjacent excerpt that contains the anchor's position,
5130                // then report that the anchor has lost its position.
5131                if !kept_position {
5132                    anchor = if let Some(excerpt) = next_excerpt {
5133                        let mut text_anchor = excerpt
5134                            .range
5135                            .context
5136                            .start
5137                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5138                        if text_anchor
5139                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5140                            .is_gt()
5141                        {
5142                            text_anchor = excerpt.range.context.end;
5143                        }
5144                        Anchor {
5145                            buffer_id: Some(excerpt.buffer_id),
5146                            excerpt_id: excerpt.id,
5147                            text_anchor,
5148                            diff_base_anchor: None,
5149                        }
5150                    } else if let Some(excerpt) = prev_excerpt {
5151                        let mut text_anchor = excerpt
5152                            .range
5153                            .context
5154                            .end
5155                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5156                        if text_anchor
5157                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5158                            .is_lt()
5159                        {
5160                            text_anchor = excerpt.range.context.start;
5161                        }
5162                        Anchor {
5163                            buffer_id: Some(excerpt.buffer_id),
5164                            excerpt_id: excerpt.id,
5165                            text_anchor,
5166                            diff_base_anchor: None,
5167                        }
5168                    } else if anchor.text_anchor.bias == Bias::Left {
5169                        Anchor::min()
5170                    } else {
5171                        Anchor::max()
5172                    };
5173                }
5174
5175                result.push((anchor_ix, anchor, kept_position));
5176            }
5177        }
5178        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5179        result
5180    }
5181
5182    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5183        self.anchor_at(position, Bias::Left)
5184    }
5185
5186    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5187        self.anchor_at(position, Bias::Right)
5188    }
5189
5190    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5191        let offset = position.to_offset(self);
5192
5193        // Find the given position in the diff transforms. Determine the corresponding
5194        // offset in the excerpts, and whether the position is within a deleted hunk.
5195        let mut diff_transforms = self
5196            .diff_transforms
5197            .cursor::<Dimensions<usize, ExcerptOffset>>(());
5198        diff_transforms.seek(&offset, Bias::Right);
5199
5200        if offset == diff_transforms.start().0
5201            && bias == Bias::Left
5202            && let Some(prev_item) = diff_transforms.prev_item()
5203            && let DiffTransform::DeletedHunk { .. } = prev_item
5204        {
5205            diff_transforms.prev();
5206        }
5207        let offset_in_transform = offset - diff_transforms.start().0;
5208        let mut excerpt_offset = diff_transforms.start().1;
5209        let mut diff_base_anchor = None;
5210        if let Some(DiffTransform::DeletedHunk {
5211            buffer_id,
5212            base_text_byte_range,
5213            has_trailing_newline,
5214            ..
5215        }) = diff_transforms.item()
5216        {
5217            let diff = self.diffs.get(buffer_id).expect("missing diff");
5218            if offset_in_transform > base_text_byte_range.len() {
5219                debug_assert!(*has_trailing_newline);
5220                bias = Bias::Right;
5221            } else {
5222                diff_base_anchor = Some(
5223                    diff.base_text()
5224                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5225                );
5226                bias = Bias::Left;
5227            }
5228        } else {
5229            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5230        };
5231
5232        let mut excerpts = self
5233            .excerpts
5234            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5235        excerpts.seek(&excerpt_offset, Bias::Right);
5236        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5237            excerpts.prev();
5238        }
5239        if let Some(excerpt) = excerpts.item() {
5240            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5241            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5242                overshoot -= 1;
5243                bias = Bias::Right;
5244            }
5245
5246            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5247            let text_anchor =
5248                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5249            Anchor {
5250                buffer_id: Some(excerpt.buffer_id),
5251                excerpt_id: excerpt.id,
5252                text_anchor,
5253                diff_base_anchor,
5254            }
5255        } else {
5256            let mut anchor = if excerpt_offset.is_zero() && bias == Bias::Left {
5257                Anchor::min()
5258            } else {
5259                Anchor::max()
5260            };
5261
5262            // TODO this is a hack, because all APIs should be able to handle ExcerptId::min and max.
5263            if let Some((excerpt_id, _, _)) = self.as_singleton() {
5264                anchor.excerpt_id = *excerpt_id;
5265            }
5266            anchor
5267        }
5268    }
5269
5270    /// Returns an anchor for the given excerpt and text anchor,
5271    /// returns None if the excerpt_id is no longer valid.
5272    pub fn anchor_in_excerpt(
5273        &self,
5274        excerpt_id: ExcerptId,
5275        text_anchor: text::Anchor,
5276    ) -> Option<Anchor> {
5277        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5278        let locator = self.excerpt_locator_for_id(excerpt_id);
5279        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5280        cursor.seek(locator, Bias::Left);
5281        if let Some(excerpt) = cursor.item()
5282            && excerpt.id == excerpt_id
5283        {
5284            let text_anchor = excerpt.clip_anchor(text_anchor);
5285            drop(cursor);
5286            return Some(Anchor {
5287                buffer_id: Some(excerpt.buffer_id),
5288                excerpt_id,
5289                text_anchor,
5290                diff_base_anchor: None,
5291            });
5292        }
5293        None
5294    }
5295
5296    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5297        Some(self.excerpt(excerpt_id)?.range.context.clone())
5298    }
5299
5300    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5301        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5302            true
5303        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5304            excerpt.buffer.can_resolve(&anchor.text_anchor)
5305        } else {
5306            false
5307        }
5308    }
5309
5310    pub fn excerpts(
5311        &self,
5312    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5313        self.excerpts
5314            .iter()
5315            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5316    }
5317
5318    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5319        let excerpts = self.excerpts.cursor(());
5320        let diff_transforms = self.diff_transforms.cursor(());
5321        MultiBufferCursor {
5322            excerpts,
5323            diff_transforms,
5324            diffs: &self.diffs,
5325            cached_region: None,
5326        }
5327    }
5328
5329    pub fn excerpt_before(&self, id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5330        let start_locator = self.excerpt_locator_for_id(id);
5331        let mut excerpts = self
5332            .excerpts
5333            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(());
5334        excerpts.seek(&Some(start_locator), Bias::Left);
5335        excerpts.prev();
5336
5337        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(());
5338        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5339        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5340            diff_transforms.next();
5341        }
5342
5343        let excerpt = excerpts.item()?;
5344        Some(MultiBufferExcerpt {
5345            excerpt,
5346            offset: diff_transforms.start().output_dimension.0,
5347            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5348            excerpt_offset: excerpts.start().1.clone(),
5349            diff_transforms,
5350        })
5351    }
5352
5353    pub fn excerpt_boundaries_in_range<R, T>(
5354        &self,
5355        range: R,
5356    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5357    where
5358        R: RangeBounds<T>,
5359        T: ToOffset,
5360    {
5361        let start_offset;
5362        let start = match range.start_bound() {
5363            Bound::Included(start) => {
5364                start_offset = start.to_offset(self);
5365                Bound::Included(start_offset)
5366            }
5367            Bound::Excluded(_) => {
5368                panic!("not supported")
5369            }
5370            Bound::Unbounded => {
5371                start_offset = 0;
5372                Bound::Unbounded
5373            }
5374        };
5375        let end = match range.end_bound() {
5376            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5377            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5378            Bound::Unbounded => Bound::Unbounded,
5379        };
5380        let bounds = (start, end);
5381
5382        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5383        cursor.seek(&DimensionPair {
5384            key: start_offset,
5385            value: None,
5386        });
5387
5388        if cursor
5389            .region()
5390            .is_some_and(|region| bounds.contains(&region.range.start.key))
5391        {
5392            cursor.prev_excerpt();
5393        } else {
5394            cursor.seek_to_start_of_current_excerpt();
5395        }
5396        let mut prev_region = cursor.region();
5397
5398        cursor.next_excerpt();
5399
5400        iter::from_fn(move || {
5401            loop {
5402                if self.singleton {
5403                    return None;
5404                }
5405
5406                let next_region = cursor.region()?;
5407                cursor.next_excerpt();
5408                if !bounds.contains(&next_region.range.start.key) {
5409                    prev_region = Some(next_region);
5410                    continue;
5411                }
5412
5413                let next_region_start = next_region.range.start.value.unwrap();
5414                let next_region_end = if let Some(region) = cursor.region() {
5415                    region.range.start.value.unwrap()
5416                } else {
5417                    self.max_point()
5418                };
5419
5420                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5421                    id: region.excerpt.id,
5422                    buffer: region.excerpt.buffer.clone(),
5423                    buffer_id: region.excerpt.buffer_id,
5424                    range: region.excerpt.range.clone(),
5425                    end_row: MultiBufferRow(next_region_start.row),
5426                });
5427
5428                let next = ExcerptInfo {
5429                    id: next_region.excerpt.id,
5430                    buffer: next_region.excerpt.buffer.clone(),
5431                    buffer_id: next_region.excerpt.buffer_id,
5432                    range: next_region.excerpt.range.clone(),
5433                    end_row: if next_region.excerpt.has_trailing_newline {
5434                        MultiBufferRow(next_region_end.row - 1)
5435                    } else {
5436                        MultiBufferRow(next_region_end.row)
5437                    },
5438                };
5439
5440                let row = MultiBufferRow(next_region_start.row);
5441
5442                prev_region = Some(next_region);
5443
5444                return Some(ExcerptBoundary { row, prev, next });
5445            }
5446        })
5447    }
5448
5449    pub fn edit_count(&self) -> usize {
5450        self.edit_count
5451    }
5452
5453    pub fn non_text_state_update_count(&self) -> usize {
5454        self.non_text_state_update_count
5455    }
5456
5457    /// Returns the smallest enclosing bracket ranges containing the given range or
5458    /// None if no brackets contain range or the range is not contained in a single
5459    /// excerpt
5460    ///
5461    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5462    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5463        &self,
5464        range: Range<T>,
5465        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5466    ) -> Option<(Range<usize>, Range<usize>)> {
5467        let range = range.start.to_offset(self)..range.end.to_offset(self);
5468        let mut excerpt = self.excerpt_containing(range.clone())?;
5469        let buffer = excerpt.buffer();
5470        let excerpt_buffer_range = excerpt.buffer_range();
5471
5472        // Filter to ranges contained in the excerpt
5473        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5474            excerpt_buffer_range.contains(&open.start)
5475                && excerpt_buffer_range.contains(&close.end)
5476                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5477        };
5478
5479        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5480            excerpt.map_range_to_buffer(range),
5481            Some(&range_filter),
5482        )?;
5483
5484        Some((
5485            excerpt.map_range_from_buffer(open),
5486            excerpt.map_range_from_buffer(close),
5487        ))
5488    }
5489
5490    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5491    /// not contained in a single excerpt
5492    pub fn enclosing_bracket_ranges<T: ToOffset>(
5493        &self,
5494        range: Range<T>,
5495    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5496        let range = range.start.to_offset(self)..range.end.to_offset(self);
5497        let mut excerpt = self.excerpt_containing(range.clone())?;
5498
5499        Some(
5500            excerpt
5501                .buffer()
5502                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5503                .filter_map(move |pair| {
5504                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5505                        Some((
5506                            excerpt.map_range_from_buffer(pair.open_range),
5507                            excerpt.map_range_from_buffer(pair.close_range),
5508                        ))
5509                    } else {
5510                        None
5511                    }
5512                }),
5513        )
5514    }
5515
5516    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5517    /// not contained in a single excerpt
5518    pub fn text_object_ranges<T: ToOffset>(
5519        &self,
5520        range: Range<T>,
5521        options: TreeSitterOptions,
5522    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5523        let range = range.start.to_offset(self)..range.end.to_offset(self);
5524        self.excerpt_containing(range.clone())
5525            .map(|mut excerpt| {
5526                excerpt
5527                    .buffer()
5528                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5529                    .filter_map(move |(range, text_object)| {
5530                        if excerpt.contains_buffer_range(range.clone()) {
5531                            Some((excerpt.map_range_from_buffer(range), text_object))
5532                        } else {
5533                            None
5534                        }
5535                    })
5536            })
5537            .into_iter()
5538            .flatten()
5539    }
5540
5541    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5542    /// not contained in a single excerpt
5543    pub fn bracket_ranges<T: ToOffset>(
5544        &self,
5545        range: Range<T>,
5546    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5547        let range = range.start.to_offset(self)..range.end.to_offset(self);
5548        let mut excerpt = self.excerpt_containing(range.clone())?;
5549
5550        Some(
5551            excerpt
5552                .buffer()
5553                .bracket_ranges(excerpt.map_range_to_buffer(range))
5554                .filter_map(move |pair| {
5555                    let buffer_range = pair.open_range.start..pair.close_range.end;
5556                    if excerpt.contains_buffer_range(buffer_range) {
5557                        Some((
5558                            excerpt.map_range_from_buffer(pair.open_range),
5559                            excerpt.map_range_from_buffer(pair.close_range),
5560                        ))
5561                    } else {
5562                        None
5563                    }
5564                }),
5565        )
5566    }
5567
5568    pub fn redacted_ranges<'a, T: ToOffset>(
5569        &'a self,
5570        range: Range<T>,
5571        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5572    ) -> impl Iterator<Item = Range<usize>> + 'a {
5573        let range = range.start.to_offset(self)..range.end.to_offset(self);
5574        self.lift_buffer_metadata(range, move |buffer, range| {
5575            if redaction_enabled(buffer.file()) {
5576                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5577            } else {
5578                None
5579            }
5580        })
5581        .map(|(range, _, _)| range)
5582    }
5583
5584    pub fn runnable_ranges(
5585        &self,
5586        range: Range<Anchor>,
5587    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5588        let range = range.start.to_offset(self)..range.end.to_offset(self);
5589        self.lift_buffer_metadata(range, move |buffer, range| {
5590            Some(
5591                buffer
5592                    .runnable_ranges(range.clone())
5593                    .filter(move |runnable| {
5594                        runnable.run_range.start >= range.start
5595                            && runnable.run_range.end < range.end
5596                    })
5597                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5598            )
5599        })
5600        .map(|(run_range, runnable, _)| language::RunnableRange {
5601            run_range,
5602            ..runnable
5603        })
5604    }
5605
5606    pub fn line_indents(
5607        &self,
5608        start_row: MultiBufferRow,
5609        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5610    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5611        let max_point = self.max_point();
5612        let mut cursor = self.cursor::<Point>();
5613        cursor.seek(&Point::new(start_row.0, 0));
5614        iter::from_fn(move || {
5615            let mut region = cursor.region()?;
5616            while !buffer_filter(&region.excerpt.buffer) {
5617                cursor.next();
5618                region = cursor.region()?;
5619            }
5620            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5621            let buffer_start_row =
5622                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5623
5624            let buffer_end_row = if region.is_main_buffer
5625                && (region.has_trailing_newline || region.range.end == max_point)
5626            {
5627                region.buffer_range.end.row
5628            } else {
5629                region.buffer_range.end.row.saturating_sub(1)
5630            };
5631
5632            let line_indents = region
5633                .buffer
5634                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5635            cursor.next();
5636            Some(line_indents.map(move |(buffer_row, indent)| {
5637                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5638                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5639            }))
5640        })
5641        .flatten()
5642    }
5643
5644    pub fn reversed_line_indents(
5645        &self,
5646        end_row: MultiBufferRow,
5647        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5648    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5649        let max_point = self.max_point();
5650        let mut cursor = self.cursor::<Point>();
5651        cursor.seek(&Point::new(end_row.0, 0));
5652        iter::from_fn(move || {
5653            let mut region = cursor.region()?;
5654            while !buffer_filter(&region.excerpt.buffer) {
5655                cursor.prev();
5656                region = cursor.region()?;
5657            }
5658
5659            let buffer_start_row = region.buffer_range.start.row;
5660            let buffer_end_row = if region.is_main_buffer
5661                && (region.has_trailing_newline || region.range.end == max_point)
5662            {
5663                region.buffer_range.end.row + 1
5664            } else {
5665                region.buffer_range.end.row
5666            };
5667
5668            let overshoot = end_row.0 - region.range.start.row;
5669            let buffer_end_row =
5670                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5671
5672            let line_indents = region
5673                .buffer
5674                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5675            cursor.prev();
5676            Some(line_indents.map(move |(buffer_row, indent)| {
5677                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5678                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5679            }))
5680        })
5681        .flatten()
5682    }
5683
5684    pub async fn enclosing_indent(
5685        &self,
5686        mut target_row: MultiBufferRow,
5687    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5688        let max_row = MultiBufferRow(self.max_point().row);
5689        if target_row >= max_row {
5690            return None;
5691        }
5692
5693        let mut target_indent = self.line_indent_for_row(target_row);
5694
5695        // If the current row is at the start of an indented block, we want to return this
5696        // block as the enclosing indent.
5697        if !target_indent.is_line_empty() && target_row < max_row {
5698            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5699            if !next_line_indent.is_line_empty()
5700                && target_indent.raw_len() < next_line_indent.raw_len()
5701            {
5702                target_indent = next_line_indent;
5703                target_row.0 += 1;
5704            }
5705        }
5706
5707        const SEARCH_ROW_LIMIT: u32 = 25000;
5708        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5709        const YIELD_INTERVAL: u32 = 100;
5710
5711        let mut accessed_row_counter = 0;
5712
5713        // If there is a blank line at the current row, search for the next non indented lines
5714        if target_indent.is_line_empty() {
5715            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5716            let end =
5717                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5718
5719            let mut non_empty_line_above = None;
5720            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5721                if row < start {
5722                    break;
5723                }
5724                accessed_row_counter += 1;
5725                if accessed_row_counter == YIELD_INTERVAL {
5726                    accessed_row_counter = 0;
5727                    yield_now().await;
5728                }
5729                if !indent.is_line_empty() {
5730                    non_empty_line_above = Some((row, indent));
5731                    break;
5732                }
5733            }
5734
5735            let mut non_empty_line_below = None;
5736            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5737                if row > end {
5738                    break;
5739                }
5740                accessed_row_counter += 1;
5741                if accessed_row_counter == YIELD_INTERVAL {
5742                    accessed_row_counter = 0;
5743                    yield_now().await;
5744                }
5745                if !indent.is_line_empty() {
5746                    non_empty_line_below = Some((row, indent));
5747                    break;
5748                }
5749            }
5750
5751            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5752                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5753                    if above_indent.raw_len() >= below_indent.raw_len() {
5754                        (above_row, above_indent)
5755                    } else {
5756                        (below_row, below_indent)
5757                    }
5758                }
5759                (Some(above), None) => above,
5760                (None, Some(below)) => below,
5761                _ => return None,
5762            };
5763
5764            target_indent = indent;
5765            target_row = row;
5766        }
5767
5768        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5769        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5770
5771        let mut start_indent = None;
5772        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5773            if row < start {
5774                break;
5775            }
5776            accessed_row_counter += 1;
5777            if accessed_row_counter == YIELD_INTERVAL {
5778                accessed_row_counter = 0;
5779                yield_now().await;
5780            }
5781            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5782                start_indent = Some((row, indent));
5783                break;
5784            }
5785        }
5786        let (start_row, start_indent_size) = start_indent?;
5787
5788        let mut end_indent = (end, None);
5789        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5790            if row > end {
5791                break;
5792            }
5793            accessed_row_counter += 1;
5794            if accessed_row_counter == YIELD_INTERVAL {
5795                accessed_row_counter = 0;
5796                yield_now().await;
5797            }
5798            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5799                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5800                break;
5801            }
5802        }
5803        let (end_row, end_indent_size) = end_indent;
5804
5805        let indent = if let Some(end_indent_size) = end_indent_size {
5806            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5807                start_indent_size
5808            } else {
5809                end_indent_size
5810            }
5811        } else {
5812            start_indent_size
5813        };
5814
5815        Some((start_row..end_row, indent))
5816    }
5817
5818    pub fn indent_guides_in_range<T: ToPoint>(
5819        &self,
5820        range: Range<T>,
5821        ignore_disabled_for_language: bool,
5822        cx: &App,
5823    ) -> impl Iterator<Item = IndentGuide> {
5824        let range = range.start.to_point(self)..range.end.to_point(self);
5825        let start_row = MultiBufferRow(range.start.row);
5826        let end_row = MultiBufferRow(range.end.row);
5827
5828        let mut row_indents = self.line_indents(start_row, |buffer| {
5829            let settings =
5830                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5831            settings.indent_guides.enabled || ignore_disabled_for_language
5832        });
5833
5834        let mut result = Vec::new();
5835        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5836
5837        let mut prev_settings = None;
5838        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5839            if first_row > end_row {
5840                break;
5841            }
5842            let current_depth = indent_stack.len() as u32;
5843
5844            // Avoid retrieving the language settings repeatedly for every buffer row.
5845            if let Some((prev_buffer_id, _)) = &prev_settings
5846                && prev_buffer_id != &buffer.remote_id()
5847            {
5848                prev_settings.take();
5849            }
5850            let settings = &prev_settings
5851                .get_or_insert_with(|| {
5852                    (
5853                        buffer.remote_id(),
5854                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5855                    )
5856                })
5857                .1;
5858            let tab_size = settings.tab_size.get();
5859
5860            // When encountering empty, continue until found useful line indent
5861            // then add to the indent stack with the depth found
5862            let mut found_indent = false;
5863            let mut last_row = first_row;
5864            if line_indent.is_line_blank() {
5865                while !found_indent {
5866                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5867                        break;
5868                    };
5869                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5870                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5871                        break;
5872                    }
5873
5874                    if new_line_indent.is_line_blank() {
5875                        continue;
5876                    }
5877                    last_row = target_row.min(end_row);
5878                    line_indent = new_line_indent;
5879                    found_indent = true;
5880                    break;
5881                }
5882            } else {
5883                found_indent = true
5884            }
5885
5886            let depth = if found_indent {
5887                line_indent.len(tab_size) / tab_size
5888            } else {
5889                0
5890            };
5891
5892            match depth.cmp(&current_depth) {
5893                cmp::Ordering::Less => {
5894                    for _ in 0..(current_depth - depth) {
5895                        let mut indent = indent_stack.pop().unwrap();
5896                        if last_row != first_row {
5897                            // In this case, we landed on an empty row, had to seek forward,
5898                            // and discovered that the indent we where on is ending.
5899                            // This means that the last display row must
5900                            // be on line that ends this indent range, so we
5901                            // should display the range up to the first non-empty line
5902                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5903                        }
5904
5905                        result.push(indent)
5906                    }
5907                }
5908                cmp::Ordering::Greater => {
5909                    for next_depth in current_depth..depth {
5910                        indent_stack.push(IndentGuide {
5911                            buffer_id: buffer.remote_id(),
5912                            start_row: first_row,
5913                            end_row: last_row,
5914                            depth: next_depth,
5915                            tab_size,
5916                            settings: settings.indent_guides.clone(),
5917                        });
5918                    }
5919                }
5920                _ => {}
5921            }
5922
5923            for indent in indent_stack.iter_mut() {
5924                indent.end_row = last_row;
5925            }
5926        }
5927
5928        result.extend(indent_stack);
5929        result.into_iter()
5930    }
5931
5932    pub fn trailing_excerpt_update_count(&self) -> usize {
5933        self.trailing_excerpt_update_count
5934    }
5935
5936    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5937        self.point_to_buffer_offset(point)
5938            .and_then(|(buffer, _)| buffer.file())
5939    }
5940
5941    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5942        self.point_to_buffer_offset(point)
5943            .and_then(|(buffer, offset)| buffer.language_at(offset))
5944    }
5945
5946    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5947        self.excerpts
5948            .first()
5949            .map(|excerpt| &excerpt.buffer)
5950            .map(|buffer| {
5951                language_settings(
5952                    buffer.language().map(|language| language.name()),
5953                    buffer.file(),
5954                    cx,
5955                )
5956            })
5957            .unwrap_or_else(move || self.language_settings_at(0, cx))
5958    }
5959
5960    pub fn language_settings_at<'a, T: ToOffset>(
5961        &'a self,
5962        point: T,
5963        cx: &'a App,
5964    ) -> Cow<'a, LanguageSettings> {
5965        let mut language = None;
5966        let mut file = None;
5967        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5968            language = buffer.language_at(offset);
5969            file = buffer.file();
5970        }
5971        language_settings(language.map(|l| l.name()), file, cx)
5972    }
5973
5974    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5975        self.point_to_buffer_offset(point)
5976            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5977    }
5978
5979    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5980        self.point_to_buffer_offset(point)
5981            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5982            .unwrap_or_default()
5983    }
5984
5985    pub fn language_indent_size_at<T: ToOffset>(
5986        &self,
5987        position: T,
5988        cx: &App,
5989    ) -> Option<IndentSize> {
5990        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5991        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5992    }
5993
5994    pub fn is_dirty(&self) -> bool {
5995        self.is_dirty
5996    }
5997
5998    pub fn has_deleted_file(&self) -> bool {
5999        self.has_deleted_file
6000    }
6001
6002    pub fn has_conflict(&self) -> bool {
6003        self.has_conflict
6004    }
6005
6006    pub fn has_diagnostics(&self) -> bool {
6007        self.excerpts
6008            .iter()
6009            .any(|excerpt| excerpt.buffer.has_diagnostics())
6010    }
6011
6012    pub fn diagnostic_group(
6013        &self,
6014        buffer_id: BufferId,
6015        group_id: usize,
6016    ) -> impl Iterator<Item = DiagnosticEntry<Point>> + '_ {
6017        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
6018            if buffer.remote_id() != buffer_id {
6019                return None;
6020            };
6021            Some(
6022                buffer
6023                    .diagnostics_in_range(range, false)
6024                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
6025                    .map(move |DiagnosticEntry { diagnostic, range }| (range, diagnostic)),
6026            )
6027        })
6028        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
6029    }
6030
6031    pub fn diagnostics_in_range<'a, T>(
6032        &'a self,
6033        range: Range<T>,
6034    ) -> impl Iterator<Item = DiagnosticEntry<T>> + 'a
6035    where
6036        T: 'a
6037            + text::ToOffset
6038            + text::FromAnchor
6039            + TextDimension
6040            + Ord
6041            + Sub<T, Output = T>
6042            + fmt::Debug,
6043    {
6044        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6045            Some(
6046                buffer
6047                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6048                    .map(|entry| (entry.range, entry.diagnostic)),
6049            )
6050        })
6051        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
6052    }
6053
6054    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6055        &'a self,
6056        range: Range<T>,
6057    ) -> impl Iterator<Item = (BufferId, DiagnosticEntry<T>)> + 'a
6058    where
6059        T: 'a
6060            + text::ToOffset
6061            + text::FromAnchor
6062            + TextDimension
6063            + Ord
6064            + Sub<T, Output = T>
6065            + fmt::Debug,
6066    {
6067        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6068            Some(
6069                buffer
6070                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6071                    .map(|entry| (entry.range, entry.diagnostic)),
6072            )
6073        })
6074        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntry { diagnostic, range }))
6075    }
6076
6077    pub fn syntax_ancestor<T: ToOffset>(
6078        &self,
6079        range: Range<T>,
6080    ) -> Option<(tree_sitter::Node<'_>, MultiOrSingleBufferOffsetRange)> {
6081        let range = range.start.to_offset(self)..range.end.to_offset(self);
6082        let mut excerpt = self.excerpt_containing(range.clone())?;
6083        let node = excerpt
6084            .buffer()
6085            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6086        let node_range = node.byte_range();
6087        let range = if excerpt.contains_buffer_range(node_range.clone()) {
6088            MultiOrSingleBufferOffsetRange::Multi(excerpt.map_range_from_buffer(node_range))
6089        } else {
6090            MultiOrSingleBufferOffsetRange::Single(node_range)
6091        };
6092        Some((node, range))
6093    }
6094
6095    pub fn syntax_next_sibling<T: ToOffset>(
6096        &self,
6097        range: Range<T>,
6098    ) -> Option<tree_sitter::Node<'_>> {
6099        let range = range.start.to_offset(self)..range.end.to_offset(self);
6100        let mut excerpt = self.excerpt_containing(range.clone())?;
6101        excerpt
6102            .buffer()
6103            .syntax_next_sibling(excerpt.map_range_to_buffer(range))
6104    }
6105
6106    pub fn syntax_prev_sibling<T: ToOffset>(
6107        &self,
6108        range: Range<T>,
6109    ) -> Option<tree_sitter::Node<'_>> {
6110        let range = range.start.to_offset(self)..range.end.to_offset(self);
6111        let mut excerpt = self.excerpt_containing(range.clone())?;
6112        excerpt
6113            .buffer()
6114            .syntax_prev_sibling(excerpt.map_range_to_buffer(range))
6115    }
6116
6117    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6118        let (excerpt_id, _, buffer) = self.as_singleton()?;
6119        let outline = buffer.outline(theme);
6120        Some(Outline::new(
6121            outline
6122                .items
6123                .into_iter()
6124                .flat_map(|item| {
6125                    Some(OutlineItem {
6126                        depth: item.depth,
6127                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6128                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6129                        text: item.text,
6130                        highlight_ranges: item.highlight_ranges,
6131                        name_ranges: item.name_ranges,
6132                        body_range: item.body_range.and_then(|body_range| {
6133                            Some(
6134                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6135                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6136                            )
6137                        }),
6138                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6139                            Some(
6140                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6141                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6142                            )
6143                        }),
6144                    })
6145                })
6146                .collect(),
6147        ))
6148    }
6149
6150    pub fn symbols_containing<T: ToOffset>(
6151        &self,
6152        offset: T,
6153        theme: Option<&SyntaxTheme>,
6154    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6155        let anchor = self.anchor_before(offset);
6156        let excerpt_id = anchor.excerpt_id;
6157        let excerpt = self.excerpt(excerpt_id)?;
6158        let buffer_id = excerpt.buffer_id;
6159        Some((
6160            buffer_id,
6161            excerpt
6162                .buffer
6163                .symbols_containing(anchor.text_anchor, theme)
6164                .into_iter()
6165                .flat_map(|item| {
6166                    Some(OutlineItem {
6167                        depth: item.depth,
6168                        range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
6169                        text: item.text,
6170                        highlight_ranges: item.highlight_ranges,
6171                        name_ranges: item.name_ranges,
6172                        body_range: item.body_range.map(|body_range| {
6173                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6174                        }),
6175                        annotation_range: item.annotation_range.map(|body_range| {
6176                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6177                        }),
6178                    })
6179                })
6180                .collect(),
6181        ))
6182    }
6183
6184    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6185        if id == ExcerptId::min() {
6186            Locator::min_ref()
6187        } else if id == ExcerptId::max() {
6188            Locator::max_ref()
6189        } else {
6190            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6191            cursor.seek(&id, Bias::Left);
6192            if let Some(entry) = cursor.item()
6193                && entry.id == id
6194            {
6195                return &entry.locator;
6196            }
6197            panic!("invalid excerpt id {id:?}")
6198        }
6199    }
6200
6201    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6202    fn excerpt_locators_for_ids(
6203        &self,
6204        ids: impl IntoIterator<Item = ExcerptId>,
6205    ) -> SmallVec<[Locator; 1]> {
6206        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6207        sorted_ids.sort_unstable();
6208        let mut locators = SmallVec::new();
6209
6210        while sorted_ids.last() == Some(&ExcerptId::max()) {
6211            sorted_ids.pop();
6212            if let Some(mapping) = self.excerpt_ids.last() {
6213                locators.push(mapping.locator.clone());
6214            }
6215        }
6216
6217        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6218        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6219            sorted_ids.next();
6220            if let Some(mapping) = self.excerpt_ids.first() {
6221                locators.push(mapping.locator.clone());
6222            }
6223        }
6224
6225        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6226        for id in sorted_ids {
6227            if cursor.seek_forward(&id, Bias::Left) {
6228                locators.push(cursor.item().unwrap().locator.clone());
6229            } else {
6230                panic!("invalid excerpt id {:?}", id);
6231            }
6232        }
6233
6234        locators.sort_unstable();
6235        locators
6236    }
6237
6238    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6239        Some(self.excerpt(excerpt_id)?.buffer_id)
6240    }
6241
6242    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6243        Some(&self.excerpt(excerpt_id)?.buffer)
6244    }
6245
6246    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6247        let mut cursor = self
6248            .excerpts
6249            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
6250        let locator = self.excerpt_locator_for_id(excerpt_id);
6251        if cursor.seek(&Some(locator), Bias::Left) {
6252            let start = cursor.start().1.clone();
6253            let end = cursor.end().1;
6254            let mut diff_transforms = self
6255                .diff_transforms
6256                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
6257            diff_transforms.seek(&start, Bias::Left);
6258            let overshoot = start.0 - diff_transforms.start().0.0;
6259            let start = diff_transforms.start().1.0 + overshoot;
6260            diff_transforms.seek(&end, Bias::Right);
6261            let overshoot = end.0 - diff_transforms.start().0.0;
6262            let end = diff_transforms.start().1.0 + overshoot;
6263            Some(start..end)
6264        } else {
6265            None
6266        }
6267    }
6268
6269    pub fn buffer_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
6270        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6271        let locator = self.excerpt_locator_for_id(excerpt_id);
6272        if cursor.seek(&Some(locator), Bias::Left)
6273            && let Some(excerpt) = cursor.item()
6274        {
6275            return Some(excerpt.range.context.clone());
6276        }
6277        None
6278    }
6279
6280    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6281        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6282        let locator = self.excerpt_locator_for_id(excerpt_id);
6283        cursor.seek(&Some(locator), Bias::Left);
6284        if let Some(excerpt) = cursor.item()
6285            && excerpt.id == excerpt_id
6286        {
6287            return Some(excerpt);
6288        }
6289        None
6290    }
6291
6292    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6293    pub fn excerpt_containing<T: ToOffset>(
6294        &self,
6295        range: Range<T>,
6296    ) -> Option<MultiBufferExcerpt<'_>> {
6297        let range = range.start.to_offset(self)..range.end.to_offset(self);
6298        let mut cursor = self.cursor::<usize>();
6299        cursor.seek(&range.start);
6300
6301        let start_excerpt = cursor.excerpt()?;
6302        if range.end != range.start {
6303            cursor.seek_forward(&range.end);
6304            if cursor.excerpt()?.id != start_excerpt.id {
6305                return None;
6306            }
6307        }
6308
6309        cursor.seek_to_start_of_current_excerpt();
6310        let region = cursor.region()?;
6311        let offset = region.range.start;
6312        let buffer_offset = start_excerpt.buffer_start_offset();
6313        let excerpt_offset = cursor.excerpts.start().clone();
6314        Some(MultiBufferExcerpt {
6315            diff_transforms: cursor.diff_transforms,
6316            excerpt: start_excerpt,
6317            offset,
6318            buffer_offset,
6319            excerpt_offset,
6320        })
6321    }
6322
6323    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
6324        if let Some(id) = anchor.buffer_id {
6325            return Some(id);
6326        }
6327        let excerpt = self.excerpt_containing(anchor..anchor)?;
6328        Some(excerpt.buffer_id())
6329    }
6330
6331    pub fn selections_in_range<'a>(
6332        &'a self,
6333        range: &'a Range<Anchor>,
6334        include_local: bool,
6335    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6336        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
6337        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6338        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6339        cursor.seek(start_locator, Bias::Left);
6340        cursor
6341            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6342            .flat_map(move |excerpt| {
6343                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6344                if excerpt.id == range.start.excerpt_id {
6345                    query_range.start = range.start.text_anchor;
6346                }
6347                if excerpt.id == range.end.excerpt_id {
6348                    query_range.end = range.end.text_anchor;
6349                }
6350
6351                excerpt
6352                    .buffer
6353                    .selections_in_range(query_range, include_local)
6354                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6355                        selections.map(move |selection| {
6356                            let mut start = Anchor {
6357                                buffer_id: Some(excerpt.buffer_id),
6358                                excerpt_id: excerpt.id,
6359                                text_anchor: selection.start,
6360                                diff_base_anchor: None,
6361                            };
6362                            let mut end = Anchor {
6363                                buffer_id: Some(excerpt.buffer_id),
6364                                excerpt_id: excerpt.id,
6365                                text_anchor: selection.end,
6366                                diff_base_anchor: None,
6367                            };
6368                            if range.start.cmp(&start, self).is_gt() {
6369                                start = range.start;
6370                            }
6371                            if range.end.cmp(&end, self).is_lt() {
6372                                end = range.end;
6373                            }
6374
6375                            (
6376                                replica_id,
6377                                line_mode,
6378                                cursor_shape,
6379                                Selection {
6380                                    id: selection.id,
6381                                    start,
6382                                    end,
6383                                    reversed: selection.reversed,
6384                                    goal: selection.goal,
6385                                },
6386                            )
6387                        })
6388                    })
6389            })
6390    }
6391
6392    pub fn show_headers(&self) -> bool {
6393        self.show_headers
6394    }
6395
6396    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6397        self.diffs.get(&buffer_id)
6398    }
6399
6400    /// Visually annotates a position or range with the `Debug` representation of a value. The
6401    /// callsite of this function is used as a key - previous annotations will be removed.
6402    #[cfg(debug_assertions)]
6403    #[track_caller]
6404    pub fn debug<V, R>(&self, ranges: &R, value: V)
6405    where
6406        R: debug::ToMultiBufferDebugRanges,
6407        V: std::fmt::Debug,
6408    {
6409        self.debug_with_key(std::panic::Location::caller(), ranges, value);
6410    }
6411
6412    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
6413    /// debug annotations with the same key will be removed. The key is also used to determine the
6414    /// annotation's color.
6415    #[cfg(debug_assertions)]
6416    #[track_caller]
6417    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
6418    where
6419        K: std::hash::Hash + 'static,
6420        R: debug::ToMultiBufferDebugRanges,
6421        V: std::fmt::Debug,
6422    {
6423        let text_ranges = ranges
6424            .to_multi_buffer_debug_ranges(self)
6425            .into_iter()
6426            .flat_map(|range| {
6427                self.range_to_buffer_ranges(range).into_iter().map(
6428                    |(buffer, range, _excerpt_id)| {
6429                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
6430                    },
6431                )
6432            })
6433            .collect();
6434        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
6435            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
6436        });
6437    }
6438}
6439
6440#[cfg(any(test, feature = "test-support"))]
6441impl MultiBufferSnapshot {
6442    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6443        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
6444        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
6445        start..end
6446    }
6447
6448    #[cfg(any(test, feature = "test-support"))]
6449    fn check_invariants(&self) {
6450        let excerpts = self.excerpts.items(());
6451        let excerpt_ids = self.excerpt_ids.items(());
6452
6453        for (ix, excerpt) in excerpts.iter().enumerate() {
6454            if ix == 0 {
6455                if excerpt.locator <= Locator::min() {
6456                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6457                }
6458            } else if excerpt.locator <= excerpts[ix - 1].locator {
6459                panic!("excerpts are out-of-order: {:?}", excerpts);
6460            }
6461        }
6462
6463        for (ix, entry) in excerpt_ids.iter().enumerate() {
6464            if ix == 0 {
6465                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6466                    panic!("invalid first excerpt id {:?}", entry.id);
6467                }
6468            } else if entry.id <= excerpt_ids[ix - 1].id {
6469                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6470            }
6471        }
6472
6473        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6474            panic!(
6475                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6476                self.excerpts.summary().text.len,
6477                self.diff_transforms.summary().input,
6478                self.diff_transforms.items(()),
6479            );
6480        }
6481
6482        let mut prev_transform: Option<&DiffTransform> = None;
6483        for item in self.diff_transforms.iter() {
6484            if let DiffTransform::BufferContent {
6485                summary,
6486                inserted_hunk_info,
6487            } = item
6488            {
6489                if let Some(DiffTransform::BufferContent {
6490                    inserted_hunk_info: prev_inserted_hunk_info,
6491                    ..
6492                }) = prev_transform
6493                    && *inserted_hunk_info == *prev_inserted_hunk_info
6494                {
6495                    panic!(
6496                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6497                        self.diff_transforms.items(())
6498                    );
6499                }
6500                if summary.len == 0 && !self.is_empty() {
6501                    panic!("empty buffer content transform");
6502                }
6503            }
6504            prev_transform = Some(item);
6505        }
6506    }
6507}
6508
6509impl<'a, D> MultiBufferCursor<'a, D>
6510where
6511    D: TextDimension + Ord + Sub<D, Output = D>,
6512{
6513    fn seek(&mut self, position: &D) {
6514        self.cached_region.take();
6515        self.diff_transforms
6516            .seek(&OutputDimension(*position), Bias::Right);
6517        if self.diff_transforms.item().is_none()
6518            && *position == self.diff_transforms.start().output_dimension.0
6519        {
6520            self.diff_transforms.prev();
6521        }
6522
6523        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6524        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6525            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6526            excerpt_position.add_assign(&overshoot);
6527        }
6528
6529        self.excerpts
6530            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6531        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6532            self.excerpts.prev();
6533        }
6534    }
6535
6536    fn seek_forward(&mut self, position: &D) {
6537        self.cached_region.take();
6538        self.diff_transforms
6539            .seek_forward(&OutputDimension(*position), Bias::Right);
6540        if self.diff_transforms.item().is_none()
6541            && *position == self.diff_transforms.start().output_dimension.0
6542        {
6543            self.diff_transforms.prev();
6544        }
6545
6546        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6547        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6548        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6549            excerpt_position.add_assign(&overshoot);
6550        }
6551
6552        self.excerpts
6553            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6554        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6555            self.excerpts.prev();
6556        }
6557    }
6558
6559    fn next_excerpt(&mut self) {
6560        self.excerpts.next();
6561        self.seek_to_start_of_current_excerpt();
6562    }
6563
6564    fn prev_excerpt(&mut self) {
6565        self.excerpts.prev();
6566        self.seek_to_start_of_current_excerpt();
6567    }
6568
6569    fn seek_to_start_of_current_excerpt(&mut self) {
6570        self.cached_region.take();
6571        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6572        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6573            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6574            && self.diff_transforms.next_item().is_some()
6575        {
6576            self.diff_transforms.next();
6577        }
6578    }
6579
6580    fn next(&mut self) {
6581        self.cached_region.take();
6582        match self
6583            .diff_transforms
6584            .end()
6585            .excerpt_dimension
6586            .cmp(&self.excerpts.end())
6587        {
6588            cmp::Ordering::Less => self.diff_transforms.next(),
6589            cmp::Ordering::Greater => self.excerpts.next(),
6590            cmp::Ordering::Equal => {
6591                self.diff_transforms.next();
6592                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6593                    || self.diff_transforms.item().is_none()
6594                {
6595                    self.excerpts.next();
6596                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6597                    self.diff_transforms.item()
6598                    && self
6599                        .excerpts
6600                        .item()
6601                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6602                {
6603                    self.excerpts.next();
6604                }
6605            }
6606        }
6607    }
6608
6609    fn prev(&mut self) {
6610        self.cached_region.take();
6611        match self
6612            .diff_transforms
6613            .start()
6614            .excerpt_dimension
6615            .cmp(self.excerpts.start())
6616        {
6617            cmp::Ordering::Less => self.excerpts.prev(),
6618            cmp::Ordering::Greater => self.diff_transforms.prev(),
6619            cmp::Ordering::Equal => {
6620                self.diff_transforms.prev();
6621                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6622                    || self.diff_transforms.item().is_none()
6623                {
6624                    self.excerpts.prev();
6625                }
6626            }
6627        }
6628    }
6629
6630    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6631        if self.cached_region.is_none() {
6632            self.cached_region = self.build_region();
6633        }
6634        self.cached_region.clone()
6635    }
6636
6637    fn is_at_start_of_excerpt(&mut self) -> bool {
6638        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6639            return false;
6640        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6641            return true;
6642        }
6643
6644        self.diff_transforms.prev();
6645        let prev_transform = self.diff_transforms.item();
6646        self.diff_transforms.next();
6647
6648        prev_transform.is_none_or(|next_transform| {
6649            matches!(next_transform, DiffTransform::BufferContent { .. })
6650        })
6651    }
6652
6653    fn is_at_end_of_excerpt(&mut self) -> bool {
6654        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6655            return false;
6656        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6657            || self.diff_transforms.item().is_none()
6658        {
6659            return true;
6660        }
6661
6662        let next_transform = self.diff_transforms.next_item();
6663        next_transform.is_none_or(|next_transform| match next_transform {
6664            DiffTransform::BufferContent { .. } => true,
6665            DiffTransform::DeletedHunk { hunk_info, .. } => self
6666                .excerpts
6667                .item()
6668                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6669        })
6670    }
6671
6672    fn main_buffer_position(&self) -> Option<D> {
6673        let excerpt = self.excerpts.item()?;
6674        let buffer = &excerpt.buffer;
6675        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6676        let mut buffer_start = buffer_context_start;
6677        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6678        buffer_start.add_assign(&overshoot);
6679        Some(buffer_start)
6680    }
6681
6682    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6683        let excerpt = self.excerpts.item()?;
6684        match self.diff_transforms.item()? {
6685            DiffTransform::DeletedHunk {
6686                buffer_id,
6687                base_text_byte_range,
6688                has_trailing_newline,
6689                hunk_info,
6690                ..
6691            } => {
6692                let diff = self.diffs.get(buffer_id)?;
6693                let buffer = diff.base_text();
6694                let mut rope_cursor = buffer.as_rope().cursor(0);
6695                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6696                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6697                let mut buffer_end = buffer_start;
6698                buffer_end.add_assign(&buffer_range_len);
6699                let start = self.diff_transforms.start().output_dimension.0;
6700                let end = self.diff_transforms.end().output_dimension.0;
6701                Some(MultiBufferRegion {
6702                    buffer,
6703                    excerpt,
6704                    has_trailing_newline: *has_trailing_newline,
6705                    is_main_buffer: false,
6706                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6707                        hunk_info.hunk_secondary_status,
6708                    )),
6709                    buffer_range: buffer_start..buffer_end,
6710                    range: start..end,
6711                })
6712            }
6713            DiffTransform::BufferContent {
6714                inserted_hunk_info, ..
6715            } => {
6716                let buffer = &excerpt.buffer;
6717                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6718
6719                let mut start = self.diff_transforms.start().output_dimension.0;
6720                let mut buffer_start = buffer_context_start;
6721                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6722                    let overshoot =
6723                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6724                    start.add_assign(&overshoot);
6725                } else {
6726                    let overshoot =
6727                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6728                    buffer_start.add_assign(&overshoot);
6729                }
6730
6731                let mut end;
6732                let mut buffer_end;
6733                let has_trailing_newline;
6734                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6735                    let overshoot =
6736                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6737                    end = self.diff_transforms.end().output_dimension.0;
6738                    buffer_end = buffer_context_start;
6739                    buffer_end.add_assign(&overshoot);
6740                    has_trailing_newline = false;
6741                } else {
6742                    let overshoot =
6743                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6744                    end = self.diff_transforms.start().output_dimension.0;
6745                    end.add_assign(&overshoot);
6746                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6747                    has_trailing_newline = excerpt.has_trailing_newline;
6748                };
6749
6750                Some(MultiBufferRegion {
6751                    buffer,
6752                    excerpt,
6753                    has_trailing_newline,
6754                    is_main_buffer: true,
6755                    diff_hunk_status: inserted_hunk_info
6756                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6757                    buffer_range: buffer_start..buffer_end,
6758                    range: start..end,
6759                })
6760            }
6761        }
6762    }
6763
6764    fn excerpt(&self) -> Option<&'a Excerpt> {
6765        self.excerpts.item()
6766    }
6767}
6768
6769impl History {
6770    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6771        self.transaction_depth += 1;
6772        if self.transaction_depth == 1 {
6773            let id = self.next_transaction_id.tick();
6774            self.undo_stack.push(Transaction {
6775                id,
6776                buffer_transactions: Default::default(),
6777                first_edit_at: now,
6778                last_edit_at: now,
6779                suppress_grouping: false,
6780            });
6781            Some(id)
6782        } else {
6783            None
6784        }
6785    }
6786
6787    fn end_transaction(
6788        &mut self,
6789        now: Instant,
6790        buffer_transactions: HashMap<BufferId, TransactionId>,
6791    ) -> bool {
6792        assert_ne!(self.transaction_depth, 0);
6793        self.transaction_depth -= 1;
6794        if self.transaction_depth == 0 {
6795            if buffer_transactions.is_empty() {
6796                self.undo_stack.pop();
6797                false
6798            } else {
6799                self.redo_stack.clear();
6800                let transaction = self.undo_stack.last_mut().unwrap();
6801                transaction.last_edit_at = now;
6802                for (buffer_id, transaction_id) in buffer_transactions {
6803                    transaction
6804                        .buffer_transactions
6805                        .entry(buffer_id)
6806                        .or_insert(transaction_id);
6807                }
6808                true
6809            }
6810        } else {
6811            false
6812        }
6813    }
6814
6815    fn push_transaction<'a, T>(
6816        &mut self,
6817        buffer_transactions: T,
6818        now: Instant,
6819        cx: &Context<MultiBuffer>,
6820    ) where
6821        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6822    {
6823        assert_eq!(self.transaction_depth, 0);
6824        let transaction = Transaction {
6825            id: self.next_transaction_id.tick(),
6826            buffer_transactions: buffer_transactions
6827                .into_iter()
6828                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6829                .collect(),
6830            first_edit_at: now,
6831            last_edit_at: now,
6832            suppress_grouping: false,
6833        };
6834        if !transaction.buffer_transactions.is_empty() {
6835            self.undo_stack.push(transaction);
6836            self.redo_stack.clear();
6837        }
6838    }
6839
6840    fn finalize_last_transaction(&mut self) {
6841        if let Some(transaction) = self.undo_stack.last_mut() {
6842            transaction.suppress_grouping = true;
6843        }
6844    }
6845
6846    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6847        if let Some(ix) = self
6848            .undo_stack
6849            .iter()
6850            .rposition(|transaction| transaction.id == transaction_id)
6851        {
6852            Some(self.undo_stack.remove(ix))
6853        } else if let Some(ix) = self
6854            .redo_stack
6855            .iter()
6856            .rposition(|transaction| transaction.id == transaction_id)
6857        {
6858            Some(self.redo_stack.remove(ix))
6859        } else {
6860            None
6861        }
6862    }
6863
6864    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6865        self.undo_stack
6866            .iter()
6867            .find(|transaction| transaction.id == transaction_id)
6868            .or_else(|| {
6869                self.redo_stack
6870                    .iter()
6871                    .find(|transaction| transaction.id == transaction_id)
6872            })
6873    }
6874
6875    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6876        self.undo_stack
6877            .iter_mut()
6878            .find(|transaction| transaction.id == transaction_id)
6879            .or_else(|| {
6880                self.redo_stack
6881                    .iter_mut()
6882                    .find(|transaction| transaction.id == transaction_id)
6883            })
6884    }
6885
6886    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6887        assert_eq!(self.transaction_depth, 0);
6888        if let Some(transaction) = self.undo_stack.pop() {
6889            self.redo_stack.push(transaction);
6890            self.redo_stack.last_mut()
6891        } else {
6892            None
6893        }
6894    }
6895
6896    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6897        assert_eq!(self.transaction_depth, 0);
6898        if let Some(transaction) = self.redo_stack.pop() {
6899            self.undo_stack.push(transaction);
6900            self.undo_stack.last_mut()
6901        } else {
6902            None
6903        }
6904    }
6905
6906    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6907        let ix = self
6908            .undo_stack
6909            .iter()
6910            .rposition(|transaction| transaction.id == transaction_id)?;
6911        let transaction = self.undo_stack.remove(ix);
6912        self.redo_stack.push(transaction);
6913        self.redo_stack.last()
6914    }
6915
6916    fn group(&mut self) -> Option<TransactionId> {
6917        let mut count = 0;
6918        let mut transactions = self.undo_stack.iter();
6919        if let Some(mut transaction) = transactions.next_back() {
6920            while let Some(prev_transaction) = transactions.next_back() {
6921                if !prev_transaction.suppress_grouping
6922                    && transaction.first_edit_at - prev_transaction.last_edit_at
6923                        <= self.group_interval
6924                {
6925                    transaction = prev_transaction;
6926                    count += 1;
6927                } else {
6928                    break;
6929                }
6930            }
6931        }
6932        self.group_trailing(count)
6933    }
6934
6935    fn group_until(&mut self, transaction_id: TransactionId) {
6936        let mut count = 0;
6937        for transaction in self.undo_stack.iter().rev() {
6938            if transaction.id == transaction_id {
6939                self.group_trailing(count);
6940                break;
6941            } else if transaction.suppress_grouping {
6942                break;
6943            } else {
6944                count += 1;
6945            }
6946        }
6947    }
6948
6949    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6950        let new_len = self.undo_stack.len() - n;
6951        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6952        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6953            if let Some(transaction) = transactions_to_merge.last() {
6954                last_transaction.last_edit_at = transaction.last_edit_at;
6955            }
6956            for to_merge in transactions_to_merge {
6957                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6958                    last_transaction
6959                        .buffer_transactions
6960                        .entry(*buffer_id)
6961                        .or_insert(*transaction_id);
6962                }
6963            }
6964        }
6965
6966        self.undo_stack.truncate(new_len);
6967        self.undo_stack.last().map(|t| t.id)
6968    }
6969}
6970
6971impl Excerpt {
6972    fn new(
6973        id: ExcerptId,
6974        locator: Locator,
6975        buffer_id: BufferId,
6976        buffer: BufferSnapshot,
6977        range: ExcerptRange<text::Anchor>,
6978        has_trailing_newline: bool,
6979    ) -> Self {
6980        Excerpt {
6981            id,
6982            locator,
6983            max_buffer_row: range.context.end.to_point(&buffer).row,
6984            text_summary: buffer
6985                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6986            buffer_id,
6987            buffer,
6988            range,
6989            has_trailing_newline,
6990        }
6991    }
6992
6993    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6994        let content_start = self.range.context.start.to_offset(&self.buffer);
6995        let chunks_start = content_start + range.start;
6996        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6997
6998        let footer_height = if self.has_trailing_newline
6999            && range.start <= self.text_summary.len
7000            && range.end > self.text_summary.len
7001        {
7002            1
7003        } else {
7004            0
7005        };
7006
7007        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
7008
7009        ExcerptChunks {
7010            excerpt_id: self.id,
7011            content_chunks,
7012            footer_height,
7013        }
7014    }
7015
7016    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
7017        let content_start = self.range.context.start.to_offset(&self.buffer);
7018        let chunks_start = content_start + range.start;
7019        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7020        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
7021        excerpt_chunks.footer_height = if self.has_trailing_newline
7022            && range.start <= self.text_summary.len
7023            && range.end > self.text_summary.len
7024        {
7025            1
7026        } else {
7027            0
7028        };
7029    }
7030
7031    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
7032        if text_anchor
7033            .cmp(&self.range.context.start, &self.buffer)
7034            .is_lt()
7035        {
7036            self.range.context.start
7037        } else if text_anchor
7038            .cmp(&self.range.context.end, &self.buffer)
7039            .is_gt()
7040        {
7041            self.range.context.end
7042        } else {
7043            text_anchor
7044        }
7045    }
7046
7047    fn contains(&self, anchor: &Anchor) -> bool {
7048        (anchor.buffer_id == None || anchor.buffer_id == Some(self.buffer_id))
7049            && self
7050                .range
7051                .context
7052                .start
7053                .cmp(&anchor.text_anchor, &self.buffer)
7054                .is_le()
7055            && self
7056                .range
7057                .context
7058                .end
7059                .cmp(&anchor.text_anchor, &self.buffer)
7060                .is_ge()
7061    }
7062
7063    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7064    fn buffer_start_offset(&self) -> usize {
7065        self.range.context.start.to_offset(&self.buffer)
7066    }
7067
7068    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7069    fn buffer_end_offset(&self) -> usize {
7070        self.buffer_start_offset() + self.text_summary.len
7071    }
7072}
7073
7074impl<'a> MultiBufferExcerpt<'a> {
7075    pub fn id(&self) -> ExcerptId {
7076        self.excerpt.id
7077    }
7078
7079    pub fn buffer_id(&self) -> BufferId {
7080        self.excerpt.buffer_id
7081    }
7082
7083    pub fn start_anchor(&self) -> Anchor {
7084        Anchor {
7085            buffer_id: Some(self.excerpt.buffer_id),
7086            excerpt_id: self.excerpt.id,
7087            text_anchor: self.excerpt.range.context.start,
7088            diff_base_anchor: None,
7089        }
7090    }
7091
7092    pub fn end_anchor(&self) -> Anchor {
7093        Anchor {
7094            buffer_id: Some(self.excerpt.buffer_id),
7095            excerpt_id: self.excerpt.id,
7096            text_anchor: self.excerpt.range.context.end,
7097            diff_base_anchor: None,
7098        }
7099    }
7100
7101    pub fn buffer(&self) -> &'a BufferSnapshot {
7102        &self.excerpt.buffer
7103    }
7104
7105    pub fn buffer_range(&self) -> Range<usize> {
7106        self.buffer_offset
7107            ..self
7108                .excerpt
7109                .range
7110                .context
7111                .end
7112                .to_offset(&self.excerpt.buffer.text)
7113    }
7114
7115    pub fn start_offset(&self) -> usize {
7116        self.offset
7117    }
7118
7119    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7120    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7121        self.map_range_to_buffer(offset..offset).start
7122    }
7123
7124    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7125    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7126        self.diff_transforms
7127            .seek(&OutputDimension(range.start), Bias::Right);
7128        let start = self.map_offset_to_buffer_internal(range.start);
7129        let end = if range.end > range.start {
7130            self.diff_transforms
7131                .seek_forward(&OutputDimension(range.end), Bias::Right);
7132            self.map_offset_to_buffer_internal(range.end)
7133        } else {
7134            start
7135        };
7136        start..end
7137    }
7138
7139    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7140        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7141        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7142            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7143        };
7144        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7145        self.buffer_offset + offset_in_excerpt
7146    }
7147
7148    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7149    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7150        self.map_range_from_buffer(buffer_offset..buffer_offset)
7151            .start
7152    }
7153
7154    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7155    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7156        if buffer_range.start < self.buffer_offset {
7157            log::warn!(
7158                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7159            );
7160            return buffer_range;
7161        }
7162        let overshoot = buffer_range.start - self.buffer_offset;
7163        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7164        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7165        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7166            log::warn!(
7167                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7168            );
7169            return buffer_range;
7170        }
7171        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7172        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7173
7174        let end = if buffer_range.end > buffer_range.start {
7175            let overshoot = buffer_range.end - self.buffer_offset;
7176            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7177            self.diff_transforms
7178                .seek_forward(&excerpt_offset, Bias::Right);
7179            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7180            self.diff_transforms.start().output_dimension.0 + overshoot
7181        } else {
7182            start
7183        };
7184
7185        start..end
7186    }
7187
7188    /// Returns true if the entirety of the given range is in the buffer's excerpt
7189    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7190        range.start >= self.excerpt.buffer_start_offset()
7191            && range.end <= self.excerpt.buffer_end_offset()
7192    }
7193
7194    pub fn max_buffer_row(&self) -> u32 {
7195        self.excerpt.max_buffer_row
7196    }
7197}
7198
7199impl ExcerptId {
7200    pub fn min() -> Self {
7201        Self(0)
7202    }
7203
7204    pub fn max() -> Self {
7205        Self(u32::MAX)
7206    }
7207
7208    pub fn to_proto(self) -> u64 {
7209        self.0 as _
7210    }
7211
7212    pub fn from_proto(proto: u64) -> Self {
7213        Self(proto as _)
7214    }
7215
7216    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7217        let a = snapshot.excerpt_locator_for_id(*self);
7218        let b = snapshot.excerpt_locator_for_id(*other);
7219        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7220    }
7221}
7222
7223impl From<ExcerptId> for usize {
7224    fn from(val: ExcerptId) -> Self {
7225        val.0 as usize
7226    }
7227}
7228
7229impl fmt::Debug for Excerpt {
7230    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7231        f.debug_struct("Excerpt")
7232            .field("id", &self.id)
7233            .field("locator", &self.locator)
7234            .field("buffer_id", &self.buffer_id)
7235            .field("range", &self.range)
7236            .field("text_summary", &self.text_summary)
7237            .field("has_trailing_newline", &self.has_trailing_newline)
7238            .finish()
7239    }
7240}
7241
7242impl sum_tree::Item for Excerpt {
7243    type Summary = ExcerptSummary;
7244
7245    fn summary(&self, _cx: ()) -> Self::Summary {
7246        let mut text = self.text_summary;
7247        if self.has_trailing_newline {
7248            text += TextSummary::from("\n");
7249        }
7250        ExcerptSummary {
7251            excerpt_id: self.id,
7252            excerpt_locator: self.locator.clone(),
7253            widest_line_number: self.max_buffer_row,
7254            text,
7255        }
7256    }
7257}
7258
7259impl sum_tree::Item for ExcerptIdMapping {
7260    type Summary = ExcerptId;
7261
7262    fn summary(&self, _cx: ()) -> Self::Summary {
7263        self.id
7264    }
7265}
7266
7267impl sum_tree::KeyedItem for ExcerptIdMapping {
7268    type Key = ExcerptId;
7269
7270    fn key(&self) -> Self::Key {
7271        self.id
7272    }
7273}
7274
7275impl DiffTransform {
7276    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7277        match self {
7278            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7279            DiffTransform::BufferContent {
7280                inserted_hunk_info, ..
7281            } => *inserted_hunk_info,
7282        }
7283    }
7284}
7285
7286impl sum_tree::Item for DiffTransform {
7287    type Summary = DiffTransformSummary;
7288
7289    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7290        match self {
7291            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7292                input: *summary,
7293                output: *summary,
7294            },
7295            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7296                input: TextSummary::default(),
7297                output: *summary,
7298            },
7299        }
7300    }
7301}
7302
7303impl DiffTransformSummary {
7304    fn excerpt_len(&self) -> ExcerptOffset {
7305        ExcerptOffset::new(self.input.len)
7306    }
7307}
7308
7309impl sum_tree::ContextLessSummary for DiffTransformSummary {
7310    fn zero() -> Self {
7311        DiffTransformSummary {
7312            input: TextSummary::default(),
7313            output: TextSummary::default(),
7314        }
7315    }
7316
7317    fn add_summary(&mut self, other: &Self) {
7318        self.input += other.input;
7319        self.output += other.output;
7320    }
7321}
7322
7323impl sum_tree::ContextLessSummary for ExcerptId {
7324    fn zero() -> Self {
7325        Self(0)
7326    }
7327
7328    fn add_summary(&mut self, summary: &Self) {
7329        *self = cmp::max(*self, *summary);
7330    }
7331}
7332
7333impl sum_tree::ContextLessSummary for ExcerptSummary {
7334    fn zero() -> Self {
7335        Self::default()
7336    }
7337
7338    fn add_summary(&mut self, summary: &Self) {
7339        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7340        self.excerpt_locator = summary.excerpt_locator.clone();
7341        Summary::add_summary(&mut self.text, &summary.text, ());
7342        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7343    }
7344}
7345
7346impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7347    fn zero(_cx: ()) -> Self {
7348        Default::default()
7349    }
7350
7351    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7352        self.value += summary.text.len;
7353    }
7354}
7355
7356impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7357    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7358        Ord::cmp(&self.value, &cursor_location.text.len)
7359    }
7360}
7361
7362impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7363    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
7364        Ord::cmp(&Some(self), cursor_location)
7365    }
7366}
7367
7368impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7369    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7370        Ord::cmp(self, &cursor_location.excerpt_locator)
7371    }
7372}
7373
7374impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7375    fn zero(_cx: ()) -> Self {
7376        Default::default()
7377    }
7378
7379    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7380        self.value += summary.text.lines;
7381    }
7382}
7383
7384impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7385    for ExcerptDimension<D>
7386{
7387    fn zero(_: ()) -> Self {
7388        ExcerptDimension(D::default())
7389    }
7390
7391    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7392        self.0.add_assign(&D::from_text_summary(&summary.text))
7393    }
7394}
7395
7396impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7397    fn zero(_cx: ()) -> Self {
7398        Default::default()
7399    }
7400
7401    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7402        *self = Some(&summary.excerpt_locator);
7403    }
7404}
7405
7406impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7407    fn zero(_cx: ()) -> Self {
7408        Default::default()
7409    }
7410
7411    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7412        *self = Some(summary.excerpt_id);
7413    }
7414}
7415
7416#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7417struct ExcerptDimension<T>(T);
7418
7419#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7420struct OutputDimension<T>(T);
7421
7422impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7423    fn zero(_: ()) -> Self {
7424        ExcerptOffset::new(0)
7425    }
7426
7427    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7428        self.value += summary.input.len;
7429    }
7430}
7431
7432impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7433    fn zero(_: ()) -> Self {
7434        ExcerptPoint::new(0, 0)
7435    }
7436
7437    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7438        self.value += summary.input.lines;
7439    }
7440}
7441
7442impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7443    for ExcerptDimension<D>
7444{
7445    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
7446        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7447    }
7448}
7449
7450impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7451    for ExcerptDimension<D>
7452{
7453    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7454        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7455    }
7456}
7457
7458impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7459    fn zero(_: ()) -> Self {
7460        ExcerptDimension(D::default())
7461    }
7462
7463    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7464        self.0.add_assign(&D::from_text_summary(&summary.input))
7465    }
7466}
7467
7468impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7469    for OutputDimension<D>
7470{
7471    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7472        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7473    }
7474}
7475
7476impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7477    fn zero(_: ()) -> Self {
7478        OutputDimension(D::default())
7479    }
7480
7481    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7482        self.0.add_assign(&D::from_text_summary(&summary.output))
7483    }
7484}
7485
7486impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7487    fn zero(_: ()) -> Self {
7488        TextSummary::default()
7489    }
7490
7491    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7492        *self += summary.output
7493    }
7494}
7495
7496impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7497    fn zero(_: ()) -> Self {
7498        0
7499    }
7500
7501    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7502        *self += summary.output.len
7503    }
7504}
7505
7506impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7507    fn zero(_: ()) -> Self {
7508        Point::new(0, 0)
7509    }
7510
7511    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7512        *self += summary.output.lines
7513    }
7514}
7515
7516impl MultiBufferRows<'_> {
7517    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7518        self.point = Point::new(row, 0);
7519        self.cursor.seek(&self.point);
7520    }
7521}
7522
7523impl Iterator for MultiBufferRows<'_> {
7524    type Item = RowInfo;
7525
7526    fn next(&mut self) -> Option<Self::Item> {
7527        if self.is_empty && self.point.row == 0 {
7528            self.point += Point::new(1, 0);
7529            return Some(RowInfo {
7530                buffer_id: None,
7531                buffer_row: Some(0),
7532                multibuffer_row: Some(MultiBufferRow(0)),
7533                diff_status: None,
7534                expand_info: None,
7535            });
7536        }
7537
7538        let mut region = self.cursor.region()?;
7539        while self.point >= region.range.end {
7540            self.cursor.next();
7541            if let Some(next_region) = self.cursor.region() {
7542                region = next_region;
7543            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7544                let multibuffer_row = MultiBufferRow(self.point.row);
7545                let last_excerpt = self
7546                    .cursor
7547                    .excerpts
7548                    .item()
7549                    .or(self.cursor.excerpts.prev_item())?;
7550                let last_row = last_excerpt
7551                    .range
7552                    .context
7553                    .end
7554                    .to_point(&last_excerpt.buffer)
7555                    .row;
7556
7557                let first_row = last_excerpt
7558                    .range
7559                    .context
7560                    .start
7561                    .to_point(&last_excerpt.buffer)
7562                    .row;
7563
7564                let expand_info = if self.is_singleton {
7565                    None
7566                } else {
7567                    let needs_expand_up = first_row == last_row
7568                        && last_row > 0
7569                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7570                    let needs_expand_down = last_row < last_excerpt.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: last_excerpt.id,
7584                    })
7585                };
7586                self.point += Point::new(1, 0);
7587                return Some(RowInfo {
7588                    buffer_id: Some(last_excerpt.buffer_id),
7589                    buffer_row: Some(last_row),
7590                    multibuffer_row: Some(multibuffer_row),
7591                    diff_status: None,
7592                    expand_info,
7593                });
7594            } else {
7595                return None;
7596            };
7597        }
7598
7599        let overshoot = self.point - region.range.start;
7600        let buffer_point = region.buffer_range.start + overshoot;
7601        let expand_info = if self.is_singleton {
7602            None
7603        } else {
7604            let needs_expand_up = self.point.row == region.range.start.row
7605                && self.cursor.is_at_start_of_excerpt()
7606                && buffer_point.row > 0;
7607            let needs_expand_down = (region.excerpt.has_trailing_newline
7608                && self.point.row + 1 == region.range.end.row
7609                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7610                && self.cursor.is_at_end_of_excerpt()
7611                && buffer_point.row < region.buffer.max_point().row;
7612
7613            if needs_expand_up && needs_expand_down {
7614                Some(ExpandExcerptDirection::UpAndDown)
7615            } else if needs_expand_up {
7616                Some(ExpandExcerptDirection::Up)
7617            } else if needs_expand_down {
7618                Some(ExpandExcerptDirection::Down)
7619            } else {
7620                None
7621            }
7622            .map(|direction| ExpandInfo {
7623                direction,
7624                excerpt_id: region.excerpt.id,
7625            })
7626        };
7627
7628        let result = Some(RowInfo {
7629            buffer_id: Some(region.buffer.remote_id()),
7630            buffer_row: Some(buffer_point.row),
7631            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7632            diff_status: region
7633                .diff_hunk_status
7634                .filter(|_| self.point < region.range.end),
7635            expand_info,
7636        });
7637        self.point += Point::new(1, 0);
7638        result
7639    }
7640}
7641
7642impl<'a> MultiBufferChunks<'a> {
7643    pub fn offset(&self) -> usize {
7644        self.range.start
7645    }
7646
7647    pub fn seek(&mut self, range: Range<usize>) {
7648        self.diff_transforms.seek(&range.end, Bias::Right);
7649        let mut excerpt_end = self.diff_transforms.start().1;
7650        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7651            let overshoot = range.end - self.diff_transforms.start().0;
7652            excerpt_end.value += overshoot;
7653        }
7654
7655        self.diff_transforms.seek(&range.start, Bias::Right);
7656        let mut excerpt_start = self.diff_transforms.start().1;
7657        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7658            let overshoot = range.start - self.diff_transforms.start().0;
7659            excerpt_start.value += overshoot;
7660        }
7661
7662        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7663        self.buffer_chunk.take();
7664        self.range = range;
7665    }
7666
7667    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7668        self.excerpt_offset_range = new_range.clone();
7669        self.excerpts.seek(&new_range.start, Bias::Right);
7670        if let Some(excerpt) = self.excerpts.item() {
7671            let excerpt_start = *self.excerpts.start();
7672            if let Some(excerpt_chunks) = self
7673                .excerpt_chunks
7674                .as_mut()
7675                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7676            {
7677                excerpt.seek_chunks(
7678                    excerpt_chunks,
7679                    (self.excerpt_offset_range.start - excerpt_start).value
7680                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7681                );
7682            } else {
7683                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7684                    (self.excerpt_offset_range.start - excerpt_start).value
7685                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7686                    self.language_aware,
7687                ));
7688            }
7689        } else {
7690            self.excerpt_chunks = None;
7691        }
7692    }
7693
7694    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7695        loop {
7696            if self.excerpt_offset_range.is_empty() {
7697                return None;
7698            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7699                self.excerpt_offset_range.start.value += chunk.text.len();
7700                return Some(chunk);
7701            } else {
7702                self.excerpts.next();
7703                let excerpt = self.excerpts.item()?;
7704                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7705                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7706                    self.language_aware,
7707                ));
7708            }
7709        }
7710    }
7711}
7712
7713impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7714    type Item = &'a str;
7715
7716    fn next(&mut self) -> Option<Self::Item> {
7717        let mut region = self.cursor.region()?;
7718        if self.offset == region.range.start {
7719            self.cursor.prev();
7720            region = self.cursor.region()?;
7721            let start_overshoot = self.start.saturating_sub(region.range.start);
7722            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7723                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7724            ));
7725        }
7726
7727        if self.offset == region.range.end && region.has_trailing_newline {
7728            self.offset -= 1;
7729            Some("\n")
7730        } else {
7731            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7732            self.offset -= chunk.len();
7733            Some(chunk)
7734        }
7735    }
7736}
7737
7738impl<'a> Iterator for MultiBufferChunks<'a> {
7739    type Item = Chunk<'a>;
7740
7741    fn next(&mut self) -> Option<Chunk<'a>> {
7742        if self.range.start >= self.range.end {
7743            return None;
7744        }
7745        if self.range.start == self.diff_transforms.end().0 {
7746            self.diff_transforms.next();
7747        }
7748
7749        let diff_transform_start = self.diff_transforms.start().0;
7750        let diff_transform_end = self.diff_transforms.end().0;
7751        debug_assert!(self.range.start < diff_transform_end);
7752
7753        let diff_transform = self.diff_transforms.item()?;
7754        match diff_transform {
7755            DiffTransform::BufferContent { .. } => {
7756                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7757                    chunk
7758                } else {
7759                    let chunk = self.next_excerpt_chunk().unwrap();
7760                    self.buffer_chunk.insert(chunk)
7761                };
7762
7763                let chunk_end = self.range.start + chunk.text.len();
7764                let diff_transform_end = diff_transform_end.min(self.range.end);
7765
7766                if diff_transform_end < chunk_end {
7767                    let split_idx = diff_transform_end - self.range.start;
7768                    let (before, after) = chunk.text.split_at(split_idx);
7769                    self.range.start = diff_transform_end;
7770                    let mask = (1 << split_idx) - 1;
7771                    let chars = chunk.chars & mask;
7772                    let tabs = chunk.tabs & mask;
7773
7774                    chunk.text = after;
7775                    chunk.chars = chunk.chars >> split_idx;
7776                    chunk.tabs = chunk.tabs >> split_idx;
7777
7778                    Some(Chunk {
7779                        text: before,
7780                        chars,
7781                        tabs,
7782                        ..chunk.clone()
7783                    })
7784                } else {
7785                    self.range.start = chunk_end;
7786                    self.buffer_chunk.take()
7787                }
7788            }
7789            DiffTransform::DeletedHunk {
7790                buffer_id,
7791                base_text_byte_range,
7792                has_trailing_newline,
7793                ..
7794            } => {
7795                let base_text_start =
7796                    base_text_byte_range.start + self.range.start - diff_transform_start;
7797                let base_text_end =
7798                    base_text_byte_range.start + self.range.end - diff_transform_start;
7799                let base_text_end = base_text_end.min(base_text_byte_range.end);
7800
7801                let mut chunks = if let Some((_, mut chunks)) = self
7802                    .diff_base_chunks
7803                    .take()
7804                    .filter(|(id, _)| id == buffer_id)
7805                {
7806                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7807                    {
7808                        chunks.seek(base_text_start..base_text_end);
7809                    }
7810                    chunks
7811                } else {
7812                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7813                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7814                };
7815
7816                let chunk = if let Some(chunk) = chunks.next() {
7817                    self.range.start += chunk.text.len();
7818                    self.diff_base_chunks = Some((*buffer_id, chunks));
7819                    chunk
7820                } else {
7821                    debug_assert!(has_trailing_newline);
7822                    self.range.start += "\n".len();
7823                    Chunk {
7824                        text: "\n",
7825                        chars: 1u128,
7826                        ..Default::default()
7827                    }
7828                };
7829                Some(chunk)
7830            }
7831        }
7832    }
7833}
7834
7835impl MultiBufferBytes<'_> {
7836    fn consume(&mut self, len: usize) {
7837        self.range.start += len;
7838        self.chunk = &self.chunk[len..];
7839
7840        if !self.range.is_empty() && self.chunk.is_empty() {
7841            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7842                self.chunk = chunk;
7843            } else if self.has_trailing_newline {
7844                self.has_trailing_newline = false;
7845                self.chunk = b"\n";
7846            } else {
7847                self.cursor.next();
7848                if let Some(region) = self.cursor.region() {
7849                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7850                        region.buffer_range.start
7851                            ..(region.buffer_range.start + self.range.end - region.range.start)
7852                                .min(region.buffer_range.end),
7853                    );
7854                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7855                    self.excerpt_bytes = Some(excerpt_bytes);
7856                    self.has_trailing_newline =
7857                        region.has_trailing_newline && self.range.end >= region.range.end;
7858                    if self.chunk.is_empty() && self.has_trailing_newline {
7859                        self.has_trailing_newline = false;
7860                        self.chunk = b"\n";
7861                    }
7862                }
7863            }
7864        }
7865    }
7866}
7867
7868impl<'a> Iterator for MultiBufferBytes<'a> {
7869    type Item = &'a [u8];
7870
7871    fn next(&mut self) -> Option<Self::Item> {
7872        let chunk = self.chunk;
7873        if chunk.is_empty() {
7874            None
7875        } else {
7876            self.consume(chunk.len());
7877            Some(chunk)
7878        }
7879    }
7880}
7881
7882impl io::Read for MultiBufferBytes<'_> {
7883    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7884        let len = cmp::min(buf.len(), self.chunk.len());
7885        buf[..len].copy_from_slice(&self.chunk[..len]);
7886        if len > 0 {
7887            self.consume(len);
7888        }
7889        Ok(len)
7890    }
7891}
7892
7893impl io::Read for ReversedMultiBufferBytes<'_> {
7894    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7895        let len = cmp::min(buf.len(), self.chunk.len());
7896        buf[..len].copy_from_slice(&self.chunk[..len]);
7897        buf[..len].reverse();
7898        if len > 0 {
7899            self.range.end -= len;
7900            self.chunk = &self.chunk[..self.chunk.len() - len];
7901            if !self.range.is_empty()
7902                && self.chunk.is_empty()
7903                && let Some(chunk) = self.chunks.next()
7904            {
7905                self.chunk = chunk.as_bytes();
7906            }
7907        }
7908        Ok(len)
7909    }
7910}
7911
7912impl<'a> Iterator for ExcerptChunks<'a> {
7913    type Item = Chunk<'a>;
7914
7915    fn next(&mut self) -> Option<Self::Item> {
7916        if let Some(chunk) = self.content_chunks.next() {
7917            return Some(chunk);
7918        }
7919
7920        if self.footer_height > 0 {
7921            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7922            let chars = (1 << self.footer_height) - 1;
7923            self.footer_height = 0;
7924            return Some(Chunk {
7925                text,
7926                chars,
7927                ..Default::default()
7928            });
7929        }
7930
7931        None
7932    }
7933}
7934
7935impl ToOffset for Point {
7936    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7937        snapshot.point_to_offset(*self)
7938    }
7939}
7940
7941impl ToOffset for usize {
7942    #[track_caller]
7943    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7944        assert!(
7945            *self <= snapshot.len(),
7946            "offset {} is greater than the snapshot.len() {}",
7947            *self,
7948            snapshot.len(),
7949        );
7950        *self
7951    }
7952}
7953
7954impl ToOffset for OffsetUtf16 {
7955    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7956        snapshot.offset_utf16_to_offset(*self)
7957    }
7958}
7959
7960impl ToOffset for PointUtf16 {
7961    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7962        snapshot.point_utf16_to_offset(*self)
7963    }
7964}
7965
7966impl ToOffsetUtf16 for OffsetUtf16 {
7967    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7968        *self
7969    }
7970}
7971
7972impl ToOffsetUtf16 for usize {
7973    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7974        snapshot.offset_to_offset_utf16(*self)
7975    }
7976}
7977
7978impl ToPoint for usize {
7979    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7980        snapshot.offset_to_point(*self)
7981    }
7982}
7983
7984impl ToPoint for Point {
7985    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7986        *self
7987    }
7988}
7989
7990impl ToPointUtf16 for usize {
7991    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7992        snapshot.offset_to_point_utf16(*self)
7993    }
7994}
7995
7996impl ToPointUtf16 for Point {
7997    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7998        snapshot.point_to_point_utf16(*self)
7999    }
8000}
8001
8002impl ToPointUtf16 for PointUtf16 {
8003    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
8004        *self
8005    }
8006}
8007
8008impl From<ExcerptId> for EntityId {
8009    fn from(id: ExcerptId) -> Self {
8010        EntityId::from(id.0 as u64)
8011    }
8012}
8013
8014#[cfg(debug_assertions)]
8015pub mod debug {
8016    use super::*;
8017
8018    pub trait ToMultiBufferDebugRanges {
8019        fn to_multi_buffer_debug_ranges(&self, snapshot: &MultiBufferSnapshot)
8020        -> Vec<Range<usize>>;
8021    }
8022
8023    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
8024        fn to_multi_buffer_debug_ranges(
8025            &self,
8026            snapshot: &MultiBufferSnapshot,
8027        ) -> Vec<Range<usize>> {
8028            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
8029        }
8030    }
8031
8032    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
8033        fn to_multi_buffer_debug_ranges(
8034            &self,
8035            snapshot: &MultiBufferSnapshot,
8036        ) -> Vec<Range<usize>> {
8037            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
8038                .to_multi_buffer_debug_ranges(snapshot)
8039        }
8040    }
8041
8042    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
8043        fn to_multi_buffer_debug_ranges(
8044            &self,
8045            snapshot: &MultiBufferSnapshot,
8046        ) -> Vec<Range<usize>> {
8047            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8048        }
8049    }
8050
8051    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8052        fn to_multi_buffer_debug_ranges(
8053            &self,
8054            snapshot: &MultiBufferSnapshot,
8055        ) -> Vec<Range<usize>> {
8056            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8057        }
8058    }
8059
8060    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8061        fn to_multi_buffer_debug_ranges(
8062            &self,
8063            snapshot: &MultiBufferSnapshot,
8064        ) -> Vec<Range<usize>> {
8065            self.iter()
8066                .map(|item| {
8067                    let offset = item.to_offset(snapshot);
8068                    offset..offset
8069                })
8070                .collect()
8071        }
8072    }
8073
8074    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8075        fn to_multi_buffer_debug_ranges(
8076            &self,
8077            snapshot: &MultiBufferSnapshot,
8078        ) -> Vec<Range<usize>> {
8079            self.iter()
8080                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8081                .collect()
8082        }
8083    }
8084}