multi_buffer.rs

   1mod anchor;
   2#[cfg(test)]
   3mod multi_buffer_tests;
   4mod position;
   5
   6pub use anchor::{Anchor, AnchorRangeExt, Offset};
   7pub use position::{TypedOffset, TypedPoint, TypedRow};
   8
   9use anyhow::{Result, anyhow};
  10use buffer_diff::{
  11    BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffHunkSecondaryStatus, DiffHunkStatus,
  12    DiffHunkStatusKind,
  13};
  14use clock::ReplicaId;
  15use collections::{BTreeMap, Bound, HashMap, HashSet};
  16use gpui::{App, AppContext as _, Context, Entity, EntityId, EventEmitter, Task};
  17use itertools::Itertools;
  18use language::{
  19    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharClassifier,
  20    CharKind, CharScopeContext, Chunk, CursorShape, DiagnosticEntryRef, DiskState, File,
  21    IndentGuideSettings, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16, Outline,
  22    OutlineItem, Point, PointUtf16, Selection, TextDimension, TextObject, ToOffset as _,
  23    ToPoint as _, TransactionId, TreeSitterOptions, Unclipped,
  24    language_settings::{LanguageSettings, language_settings},
  25};
  26
  27use rope::DimensionPair;
  28use smallvec::SmallVec;
  29use smol::future::yield_now;
  30use std::{
  31    any::type_name,
  32    borrow::Cow,
  33    cell::{Cell, Ref, RefCell},
  34    cmp, fmt,
  35    future::Future,
  36    io,
  37    iter::{self, FromIterator},
  38    mem,
  39    ops::{Range, RangeBounds, Sub},
  40    rc::Rc,
  41    str,
  42    sync::Arc,
  43    time::{Duration, Instant},
  44};
  45use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, Summary, TreeMap};
  46use text::{
  47    BufferId, Edit, LineIndent, TextSummary,
  48    locator::Locator,
  49    subscription::{Subscription, Topic},
  50};
  51use theme::SyntaxTheme;
  52use util::post_inc;
  53
  54const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  55
  56#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  57pub struct ExcerptId(u32);
  58
  59/// One or more [`Buffers`](Buffer) being edited in a single view.
  60///
  61/// See <https://zed.dev/features#multi-buffers>
  62pub struct MultiBuffer {
  63    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  64    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  65    snapshot: RefCell<MultiBufferSnapshot>,
  66    /// Contains the state of the buffers being edited
  67    buffers: RefCell<HashMap<BufferId, BufferState>>,
  68    // only used by consumers using `set_excerpts_for_buffer`
  69    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  70    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  71    diffs: HashMap<BufferId, DiffState>,
  72    // all_diff_hunks_expanded: bool,
  73    subscriptions: Topic,
  74    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  75    singleton: bool,
  76    history: History,
  77    title: Option<String>,
  78    capability: Capability,
  79    buffer_changed_since_sync: Rc<Cell<bool>>,
  80}
  81
  82#[derive(Clone, Debug, PartialEq, Eq)]
  83pub enum Event {
  84    ExcerptsAdded {
  85        buffer: Entity<Buffer>,
  86        predecessor: ExcerptId,
  87        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  88    },
  89    ExcerptsRemoved {
  90        ids: Vec<ExcerptId>,
  91        removed_buffer_ids: Vec<BufferId>,
  92    },
  93    ExcerptsExpanded {
  94        ids: Vec<ExcerptId>,
  95    },
  96    ExcerptsEdited {
  97        excerpt_ids: Vec<ExcerptId>,
  98        buffer_ids: Vec<BufferId>,
  99    },
 100    DiffHunksToggled,
 101    Edited {
 102        singleton_buffer_edited: bool,
 103        edited_buffer: Option<Entity<Buffer>>,
 104    },
 105    TransactionUndone {
 106        transaction_id: TransactionId,
 107    },
 108    Reloaded,
 109    LanguageChanged(BufferId),
 110    Reparsed(BufferId),
 111    Saved,
 112    FileHandleChanged,
 113    DirtyChanged,
 114    DiagnosticsUpdated,
 115    BufferDiffChanged,
 116}
 117
 118/// A diff hunk, representing a range of consequent lines in a multibuffer.
 119#[derive(Debug, Clone, PartialEq, Eq)]
 120pub struct MultiBufferDiffHunk {
 121    /// The row range in the multibuffer where this diff hunk appears.
 122    pub row_range: Range<MultiBufferRow>,
 123    /// The buffer ID that this hunk belongs to.
 124    pub buffer_id: BufferId,
 125    /// The range of the underlying buffer that this hunk corresponds to.
 126    pub buffer_range: Range<text::Anchor>,
 127    /// The excerpt that contains the diff hunk.
 128    pub excerpt_id: ExcerptId,
 129    /// The range within the buffer's diff base that this hunk corresponds to.
 130    pub diff_base_byte_range: Range<usize>,
 131    /// Whether or not this hunk also appears in the 'secondary diff'.
 132    pub secondary_status: DiffHunkSecondaryStatus,
 133}
 134
 135impl MultiBufferDiffHunk {
 136    pub fn status(&self) -> DiffHunkStatus {
 137        let kind = if self.buffer_range.start == self.buffer_range.end {
 138            DiffHunkStatusKind::Deleted
 139        } else if self.diff_base_byte_range.is_empty() {
 140            DiffHunkStatusKind::Added
 141        } else {
 142            DiffHunkStatusKind::Modified
 143        };
 144        DiffHunkStatus {
 145            kind,
 146            secondary: self.secondary_status,
 147        }
 148    }
 149
 150    pub fn is_created_file(&self) -> bool {
 151        self.diff_base_byte_range == (0..0)
 152            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 153    }
 154
 155    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 156        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 157        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 158        start..end
 159    }
 160}
 161
 162#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 163pub struct PathKey {
 164    namespace: u32,
 165    path: Arc<str>,
 166}
 167
 168impl PathKey {
 169    pub fn namespaced(namespace: u32, path: Arc<str>) -> Self {
 170        Self { namespace, path }
 171    }
 172
 173    pub fn for_buffer(buffer: &Entity<Buffer>, cx: &App) -> Self {
 174        if let Some(file) = buffer.read(cx).file() {
 175            Self::namespaced(1, file.full_path(cx).to_string_lossy().into_owned().into())
 176        } else {
 177            Self::namespaced(0, buffer.entity_id().to_string().into())
 178        }
 179    }
 180
 181    pub fn path(&self) -> &Arc<str> {
 182        &self.path
 183    }
 184}
 185
 186pub type MultiBufferPoint = Point;
 187type ExcerptOffset = TypedOffset<Excerpt>;
 188type ExcerptPoint = TypedPoint<Excerpt>;
 189
 190#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 191#[serde(transparent)]
 192pub struct MultiBufferRow(pub u32);
 193
 194impl MultiBufferRow {
 195    pub const MIN: Self = Self(0);
 196    pub const MAX: Self = Self(u32::MAX);
 197}
 198
 199impl std::ops::Add<usize> for MultiBufferRow {
 200    type Output = Self;
 201
 202    fn add(self, rhs: usize) -> Self::Output {
 203        MultiBufferRow(self.0 + rhs as u32)
 204    }
 205}
 206
 207#[derive(Clone)]
 208struct History {
 209    next_transaction_id: TransactionId,
 210    undo_stack: Vec<Transaction>,
 211    redo_stack: Vec<Transaction>,
 212    transaction_depth: usize,
 213    group_interval: Duration,
 214}
 215
 216#[derive(Clone)]
 217struct Transaction {
 218    id: TransactionId,
 219    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 220    first_edit_at: Instant,
 221    last_edit_at: Instant,
 222    suppress_grouping: bool,
 223}
 224
 225pub trait ToOffset: 'static + fmt::Debug {
 226    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 227}
 228
 229pub trait ToOffsetUtf16: 'static + fmt::Debug {
 230    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 231}
 232
 233pub trait ToPoint: 'static + fmt::Debug {
 234    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 235}
 236
 237pub trait ToPointUtf16: 'static + fmt::Debug {
 238    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 239}
 240
 241struct BufferState {
 242    buffer: Entity<Buffer>,
 243    last_version: clock::Global,
 244    last_non_text_state_update_count: usize,
 245    excerpts: Vec<Locator>,
 246    _subscriptions: [gpui::Subscription; 2],
 247}
 248
 249struct DiffState {
 250    diff: Entity<BufferDiff>,
 251    _subscription: gpui::Subscription,
 252}
 253
 254impl DiffState {
 255    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 256        DiffState {
 257            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 258                BufferDiffEvent::DiffChanged { changed_range } => {
 259                    if let Some(changed_range) = changed_range.clone() {
 260                        this.buffer_diff_changed(diff, changed_range, cx)
 261                    }
 262                    cx.emit(Event::BufferDiffChanged);
 263                }
 264                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 265                _ => {}
 266            }),
 267            diff,
 268        }
 269    }
 270}
 271
 272/// The contents of a [`MultiBuffer`] at a single point in time.
 273#[derive(Clone, Default)]
 274pub struct MultiBufferSnapshot {
 275    singleton: bool,
 276    excerpts: SumTree<Excerpt>,
 277    excerpt_ids: SumTree<ExcerptIdMapping>,
 278    diffs: TreeMap<BufferId, BufferDiffSnapshot>,
 279    diff_transforms: SumTree<DiffTransform>,
 280    replaced_excerpts: TreeMap<ExcerptId, ExcerptId>,
 281    trailing_excerpt_update_count: usize,
 282    all_diff_hunks_expanded: bool,
 283    non_text_state_update_count: usize,
 284    edit_count: usize,
 285    is_dirty: bool,
 286    has_deleted_file: bool,
 287    has_conflict: bool,
 288    show_headers: bool,
 289}
 290
 291#[derive(Debug, Clone)]
 292enum DiffTransform {
 293    BufferContent {
 294        summary: TextSummary,
 295        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 296    },
 297    DeletedHunk {
 298        summary: TextSummary,
 299        buffer_id: BufferId,
 300        hunk_info: DiffTransformHunkInfo,
 301        base_text_byte_range: Range<usize>,
 302        has_trailing_newline: bool,
 303    },
 304}
 305
 306#[derive(Clone, Copy, Debug)]
 307struct DiffTransformHunkInfo {
 308    excerpt_id: ExcerptId,
 309    hunk_start_anchor: text::Anchor,
 310    hunk_secondary_status: DiffHunkSecondaryStatus,
 311}
 312
 313impl Eq for DiffTransformHunkInfo {}
 314
 315impl PartialEq for DiffTransformHunkInfo {
 316    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 317        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 318    }
 319}
 320
 321impl std::hash::Hash for DiffTransformHunkInfo {
 322    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 323        self.excerpt_id.hash(state);
 324        self.hunk_start_anchor.hash(state);
 325    }
 326}
 327
 328#[derive(Clone)]
 329pub struct ExcerptInfo {
 330    pub id: ExcerptId,
 331    pub buffer: BufferSnapshot,
 332    pub buffer_id: BufferId,
 333    pub range: ExcerptRange<text::Anchor>,
 334    pub end_row: MultiBufferRow,
 335}
 336
 337impl std::fmt::Debug for ExcerptInfo {
 338    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 339        f.debug_struct(type_name::<Self>())
 340            .field("id", &self.id)
 341            .field("buffer_id", &self.buffer_id)
 342            .field("path", &self.buffer.file().map(|f| f.path()))
 343            .field("range", &self.range)
 344            .finish()
 345    }
 346}
 347
 348/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 349#[derive(Debug)]
 350pub struct ExcerptBoundary {
 351    pub prev: Option<ExcerptInfo>,
 352    pub next: ExcerptInfo,
 353    /// The row in the `MultiBuffer` where the boundary is located
 354    pub row: MultiBufferRow,
 355}
 356
 357impl ExcerptBoundary {
 358    pub fn starts_new_buffer(&self) -> bool {
 359        match (self.prev.as_ref(), &self.next) {
 360            (None, _) => true,
 361            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 362        }
 363    }
 364}
 365
 366#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 367pub struct ExpandInfo {
 368    pub direction: ExpandExcerptDirection,
 369    pub excerpt_id: ExcerptId,
 370}
 371
 372#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 373pub struct RowInfo {
 374    pub buffer_id: Option<BufferId>,
 375    pub buffer_row: Option<u32>,
 376    pub multibuffer_row: Option<MultiBufferRow>,
 377    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 378    pub expand_info: Option<ExpandInfo>,
 379}
 380
 381/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 382#[derive(Clone)]
 383struct Excerpt {
 384    /// The unique identifier for this excerpt
 385    id: ExcerptId,
 386    /// The location of the excerpt in the [`MultiBuffer`]
 387    locator: Locator,
 388    /// The buffer being excerpted
 389    buffer_id: BufferId,
 390    /// A snapshot of the buffer being excerpted
 391    buffer: BufferSnapshot,
 392    /// The range of the buffer to be shown in the excerpt
 393    range: ExcerptRange<text::Anchor>,
 394    /// The last row in the excerpted slice of the buffer
 395    max_buffer_row: BufferRow,
 396    /// A summary of the text in the excerpt
 397    text_summary: TextSummary,
 398    has_trailing_newline: bool,
 399}
 400
 401/// A public view into an `Excerpt` in a [`MultiBuffer`].
 402///
 403/// Contains methods for getting the [`Buffer`] of the excerpt,
 404/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 405#[derive(Clone)]
 406pub struct MultiBufferExcerpt<'a> {
 407    excerpt: &'a Excerpt,
 408    diff_transforms: sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<usize>>,
 409    offset: usize,
 410    excerpt_offset: ExcerptDimension<usize>,
 411    buffer_offset: usize,
 412}
 413
 414#[derive(Clone, Debug)]
 415struct ExcerptIdMapping {
 416    id: ExcerptId,
 417    locator: Locator,
 418}
 419
 420/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 421/// These ranges are relative to the buffer itself
 422#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 423pub struct ExcerptRange<T> {
 424    /// The full range of text to be shown in the excerpt.
 425    pub context: Range<T>,
 426    /// The primary range of text to be highlighted in the excerpt.
 427    /// In a multi-buffer search, this would be the text that matched the search
 428    pub primary: Range<T>,
 429}
 430
 431impl<T: Clone> ExcerptRange<T> {
 432    pub fn new(context: Range<T>) -> Self {
 433        Self {
 434            context: context.clone(),
 435            primary: context,
 436        }
 437    }
 438}
 439
 440#[derive(Clone, Debug, Default)]
 441pub struct ExcerptSummary {
 442    excerpt_id: ExcerptId,
 443    /// The location of the last [`Excerpt`] being summarized
 444    excerpt_locator: Locator,
 445    widest_line_number: u32,
 446    text: TextSummary,
 447}
 448
 449#[derive(Debug, Clone)]
 450pub struct DiffTransformSummary {
 451    input: TextSummary,
 452    output: TextSummary,
 453}
 454
 455#[derive(Clone)]
 456pub struct MultiBufferRows<'a> {
 457    point: Point,
 458    is_empty: bool,
 459    is_singleton: bool,
 460    cursor: MultiBufferCursor<'a, Point>,
 461}
 462
 463pub struct MultiBufferChunks<'a> {
 464    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 465    diff_transforms: Cursor<'a, 'static, DiffTransform, Dimensions<usize, ExcerptOffset>>,
 466    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 467    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 468    buffer_chunk: Option<Chunk<'a>>,
 469    range: Range<usize>,
 470    excerpt_offset_range: Range<ExcerptOffset>,
 471    excerpt_chunks: Option<ExcerptChunks<'a>>,
 472    language_aware: bool,
 473}
 474
 475pub struct ReversedMultiBufferChunks<'a> {
 476    cursor: MultiBufferCursor<'a, usize>,
 477    current_chunks: Option<rope::Chunks<'a>>,
 478    start: usize,
 479    offset: usize,
 480}
 481
 482pub struct MultiBufferBytes<'a> {
 483    range: Range<usize>,
 484    cursor: MultiBufferCursor<'a, usize>,
 485    excerpt_bytes: Option<text::Bytes<'a>>,
 486    has_trailing_newline: bool,
 487    chunk: &'a [u8],
 488}
 489
 490pub struct ReversedMultiBufferBytes<'a> {
 491    range: Range<usize>,
 492    chunks: ReversedMultiBufferChunks<'a>,
 493    chunk: &'a [u8],
 494}
 495
 496#[derive(Clone)]
 497struct DiffTransforms<D> {
 498    output_dimension: OutputDimension<D>,
 499    excerpt_dimension: ExcerptDimension<D>,
 500}
 501
 502impl<'a, D: TextDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<D> {
 503    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
 504        Self {
 505            output_dimension: OutputDimension::zero(cx),
 506            excerpt_dimension: <ExcerptDimension<D> as Dimension<'a, DiffTransformSummary>>::zero(
 507                cx,
 508            ),
 509        }
 510    }
 511
 512    fn add_summary(
 513        &mut self,
 514        summary: &'a DiffTransformSummary,
 515        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
 516    ) {
 517        self.output_dimension.add_summary(summary, cx);
 518        self.excerpt_dimension.add_summary(summary, cx);
 519    }
 520}
 521
 522#[derive(Clone)]
 523struct MultiBufferCursor<'a, D: TextDimension> {
 524    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<D>>,
 525    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<D>>,
 526    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 527    cached_region: Option<MultiBufferRegion<'a, D>>,
 528}
 529
 530#[derive(Clone)]
 531struct MultiBufferRegion<'a, D: TextDimension> {
 532    buffer: &'a BufferSnapshot,
 533    is_main_buffer: bool,
 534    diff_hunk_status: Option<DiffHunkStatus>,
 535    excerpt: &'a Excerpt,
 536    buffer_range: Range<D>,
 537    range: Range<D>,
 538    has_trailing_newline: bool,
 539}
 540
 541struct ExcerptChunks<'a> {
 542    excerpt_id: ExcerptId,
 543    content_chunks: BufferChunks<'a>,
 544    footer_height: usize,
 545}
 546
 547#[derive(Debug)]
 548struct BufferEdit {
 549    range: Range<usize>,
 550    new_text: Arc<str>,
 551    is_insertion: bool,
 552    original_indent_column: Option<u32>,
 553    excerpt_id: ExcerptId,
 554}
 555
 556#[derive(Clone, Copy, Debug, PartialEq)]
 557enum DiffChangeKind {
 558    BufferEdited,
 559    DiffUpdated { base_changed: bool },
 560    ExpandOrCollapseHunks { expand: bool },
 561}
 562
 563#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 564pub enum ExpandExcerptDirection {
 565    Up,
 566    Down,
 567    UpAndDown,
 568}
 569
 570impl ExpandExcerptDirection {
 571    pub fn should_expand_up(&self) -> bool {
 572        match self {
 573            ExpandExcerptDirection::Up => true,
 574            ExpandExcerptDirection::Down => false,
 575            ExpandExcerptDirection::UpAndDown => true,
 576        }
 577    }
 578
 579    pub fn should_expand_down(&self) -> bool {
 580        match self {
 581            ExpandExcerptDirection::Up => false,
 582            ExpandExcerptDirection::Down => true,
 583            ExpandExcerptDirection::UpAndDown => true,
 584        }
 585    }
 586}
 587
 588#[derive(Clone, Debug, PartialEq)]
 589pub struct IndentGuide {
 590    pub buffer_id: BufferId,
 591    pub start_row: MultiBufferRow,
 592    pub end_row: MultiBufferRow,
 593    pub depth: u32,
 594    pub tab_size: u32,
 595    pub settings: IndentGuideSettings,
 596}
 597
 598impl IndentGuide {
 599    pub fn indent_level(&self) -> u32 {
 600        self.depth * self.tab_size
 601    }
 602}
 603
 604impl MultiBuffer {
 605    pub fn new(capability: Capability) -> Self {
 606        Self {
 607            snapshot: RefCell::new(MultiBufferSnapshot {
 608                show_headers: true,
 609                ..MultiBufferSnapshot::default()
 610            }),
 611            buffers: RefCell::default(),
 612            diffs: HashMap::default(),
 613            subscriptions: Topic::default(),
 614            singleton: false,
 615            capability,
 616            title: None,
 617            excerpts_by_path: Default::default(),
 618            paths_by_excerpt: Default::default(),
 619            buffer_changed_since_sync: Default::default(),
 620            history: History {
 621                next_transaction_id: clock::Lamport::default(),
 622                undo_stack: Vec::new(),
 623                redo_stack: Vec::new(),
 624                transaction_depth: 0,
 625                group_interval: Duration::from_millis(300),
 626            },
 627        }
 628    }
 629
 630    pub fn without_headers(capability: Capability) -> Self {
 631        Self {
 632            snapshot: Default::default(),
 633            buffers: Default::default(),
 634            excerpts_by_path: Default::default(),
 635            paths_by_excerpt: Default::default(),
 636            diffs: HashMap::default(),
 637            subscriptions: Default::default(),
 638            singleton: false,
 639            capability,
 640            buffer_changed_since_sync: Default::default(),
 641            history: History {
 642                next_transaction_id: Default::default(),
 643                undo_stack: Default::default(),
 644                redo_stack: Default::default(),
 645                transaction_depth: 0,
 646                group_interval: Duration::from_millis(300),
 647            },
 648            title: Default::default(),
 649        }
 650    }
 651
 652    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
 653        let mut buffers = HashMap::default();
 654        let buffer_changed_since_sync = Rc::new(Cell::new(false));
 655        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 656            buffer_state.buffer.update(new_cx, |buffer, _| {
 657                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
 658            });
 659            buffers.insert(
 660                *buffer_id,
 661                BufferState {
 662                    buffer: buffer_state.buffer.clone(),
 663                    last_version: buffer_state.last_version.clone(),
 664                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 665                    excerpts: buffer_state.excerpts.clone(),
 666                    _subscriptions: [
 667                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 668                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 669                    ],
 670                },
 671            );
 672        }
 673        let mut diff_bases = HashMap::default();
 674        for (buffer_id, diff) in self.diffs.iter() {
 675            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
 676        }
 677        Self {
 678            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 679            buffers: RefCell::new(buffers),
 680            excerpts_by_path: Default::default(),
 681            paths_by_excerpt: Default::default(),
 682            diffs: diff_bases,
 683            subscriptions: Default::default(),
 684            singleton: self.singleton,
 685            capability: self.capability,
 686            history: self.history.clone(),
 687            title: self.title.clone(),
 688            buffer_changed_since_sync,
 689        }
 690    }
 691
 692    pub fn with_title(mut self, title: String) -> Self {
 693        self.title = Some(title);
 694        self
 695    }
 696
 697    pub fn read_only(&self) -> bool {
 698        self.capability == Capability::ReadOnly
 699    }
 700
 701    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
 702        let mut this = Self::new(buffer.read(cx).capability());
 703        this.singleton = true;
 704        this.push_excerpts(
 705            buffer,
 706            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
 707            cx,
 708        );
 709        this.snapshot.borrow_mut().singleton = true;
 710        this
 711    }
 712
 713    /// Returns an up-to-date snapshot of the MultiBuffer.
 714    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
 715        self.sync(cx);
 716        self.snapshot.borrow().clone()
 717    }
 718
 719    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
 720        self.sync(cx);
 721        self.snapshot.borrow()
 722    }
 723
 724    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
 725        if self.singleton {
 726            Some(
 727                self.buffers
 728                    .borrow()
 729                    .values()
 730                    .next()
 731                    .unwrap()
 732                    .buffer
 733                    .clone(),
 734            )
 735        } else {
 736            None
 737        }
 738    }
 739
 740    pub fn is_singleton(&self) -> bool {
 741        self.singleton
 742    }
 743
 744    pub fn subscribe(&mut self) -> Subscription {
 745        self.subscriptions.subscribe()
 746    }
 747
 748    pub fn is_dirty(&self, cx: &App) -> bool {
 749        self.read(cx).is_dirty()
 750    }
 751
 752    pub fn has_deleted_file(&self, cx: &App) -> bool {
 753        self.read(cx).has_deleted_file()
 754    }
 755
 756    pub fn has_conflict(&self, cx: &App) -> bool {
 757        self.read(cx).has_conflict()
 758    }
 759
 760    // The `is_empty` signature doesn't match what clippy expects
 761    #[allow(clippy::len_without_is_empty)]
 762    pub fn len(&self, cx: &App) -> usize {
 763        self.read(cx).len()
 764    }
 765
 766    pub fn is_empty(&self) -> bool {
 767        self.buffers.borrow().is_empty()
 768    }
 769
 770    pub fn symbols_containing<T: ToOffset>(
 771        &self,
 772        offset: T,
 773        theme: Option<&SyntaxTheme>,
 774        cx: &App,
 775    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 776        self.read(cx).symbols_containing(offset, theme)
 777    }
 778
 779    pub fn edit<I, S, T>(
 780        &self,
 781        edits: I,
 782        autoindent_mode: Option<AutoindentMode>,
 783        cx: &mut Context<Self>,
 784    ) where
 785        I: IntoIterator<Item = (Range<S>, T)>,
 786        S: ToOffset,
 787        T: Into<Arc<str>>,
 788    {
 789        let snapshot = self.read(cx);
 790        let edits = edits
 791            .into_iter()
 792            .map(|(range, new_text)| {
 793                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 794                if range.start > range.end {
 795                    mem::swap(&mut range.start, &mut range.end);
 796                }
 797                (range, new_text.into())
 798            })
 799            .collect::<Vec<_>>();
 800
 801        return edit_internal(self, snapshot, edits, autoindent_mode, cx);
 802
 803        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 804        fn edit_internal(
 805            this: &MultiBuffer,
 806            snapshot: Ref<MultiBufferSnapshot>,
 807            edits: Vec<(Range<usize>, Arc<str>)>,
 808            mut autoindent_mode: Option<AutoindentMode>,
 809            cx: &mut Context<MultiBuffer>,
 810        ) {
 811            if this.read_only() || this.buffers.borrow().is_empty() {
 812                return;
 813            }
 814
 815            let original_indent_columns = match &mut autoindent_mode {
 816                Some(AutoindentMode::Block {
 817                    original_indent_columns,
 818                }) => mem::take(original_indent_columns),
 819                _ => Default::default(),
 820            };
 821
 822            let (buffer_edits, edited_excerpt_ids) =
 823                this.convert_edits_to_buffer_edits(edits, &snapshot, &original_indent_columns);
 824            drop(snapshot);
 825
 826            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
 827            for (buffer_id, mut edits) in buffer_edits {
 828                buffer_ids.push(buffer_id);
 829                edits.sort_by_key(|edit| edit.range.start);
 830                this.buffers.borrow()[&buffer_id]
 831                    .buffer
 832                    .update(cx, |buffer, cx| {
 833                        let mut edits = edits.into_iter().peekable();
 834                        let mut insertions = Vec::new();
 835                        let mut original_indent_columns = Vec::new();
 836                        let mut deletions = Vec::new();
 837                        let empty_str: Arc<str> = Arc::default();
 838                        while let Some(BufferEdit {
 839                            mut range,
 840                            mut new_text,
 841                            mut is_insertion,
 842                            original_indent_column,
 843                            excerpt_id,
 844                        }) = edits.next()
 845                        {
 846                            while let Some(BufferEdit {
 847                                range: next_range,
 848                                is_insertion: next_is_insertion,
 849                                new_text: next_new_text,
 850                                excerpt_id: next_excerpt_id,
 851                                ..
 852                            }) = edits.peek()
 853                            {
 854                                if range.end >= next_range.start {
 855                                    range.end = cmp::max(next_range.end, range.end);
 856                                    is_insertion |= *next_is_insertion;
 857                                    if excerpt_id == *next_excerpt_id {
 858                                        new_text = format!("{new_text}{next_new_text}").into();
 859                                    }
 860                                    edits.next();
 861                                } else {
 862                                    break;
 863                                }
 864                            }
 865
 866                            if is_insertion {
 867                                original_indent_columns.push(original_indent_column);
 868                                insertions.push((
 869                                    buffer.anchor_before(range.start)
 870                                        ..buffer.anchor_before(range.end),
 871                                    new_text.clone(),
 872                                ));
 873                            } else if !range.is_empty() {
 874                                deletions.push((
 875                                    buffer.anchor_before(range.start)
 876                                        ..buffer.anchor_before(range.end),
 877                                    empty_str.clone(),
 878                                ));
 879                            }
 880                        }
 881
 882                        let deletion_autoindent_mode =
 883                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 884                                Some(AutoindentMode::Block {
 885                                    original_indent_columns: Default::default(),
 886                                })
 887                            } else {
 888                                autoindent_mode.clone()
 889                            };
 890                        let insertion_autoindent_mode =
 891                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 892                                Some(AutoindentMode::Block {
 893                                    original_indent_columns,
 894                                })
 895                            } else {
 896                                autoindent_mode.clone()
 897                            };
 898
 899                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 900                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 901                    })
 902            }
 903
 904            cx.emit(Event::ExcerptsEdited {
 905                excerpt_ids: edited_excerpt_ids,
 906                buffer_ids,
 907            });
 908        }
 909    }
 910
 911    fn convert_edits_to_buffer_edits(
 912        &self,
 913        edits: Vec<(Range<usize>, Arc<str>)>,
 914        snapshot: &MultiBufferSnapshot,
 915        original_indent_columns: &[Option<u32>],
 916    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
 917        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 918        let mut edited_excerpt_ids = Vec::new();
 919        let mut cursor = snapshot.cursor::<usize>();
 920        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
 921            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
 922
 923            cursor.seek(&range.start);
 924            let mut start_region = cursor.region().expect("start offset out of bounds");
 925            if !start_region.is_main_buffer {
 926                cursor.next();
 927                if let Some(region) = cursor.region() {
 928                    start_region = region;
 929                } else {
 930                    continue;
 931                }
 932            }
 933
 934            if range.end < start_region.range.start {
 935                continue;
 936            }
 937
 938            if range.end > start_region.range.end {
 939                cursor.seek_forward(&range.end);
 940            }
 941            let mut end_region = cursor.region().expect("end offset out of bounds");
 942            if !end_region.is_main_buffer {
 943                cursor.prev();
 944                if let Some(region) = cursor.region() {
 945                    end_region = region;
 946                } else {
 947                    continue;
 948                }
 949            }
 950
 951            if range.start > end_region.range.end {
 952                continue;
 953            }
 954
 955            let start_overshoot = range.start.saturating_sub(start_region.range.start);
 956            let end_overshoot = range.end.saturating_sub(end_region.range.start);
 957            let buffer_start = (start_region.buffer_range.start + start_overshoot)
 958                .min(start_region.buffer_range.end);
 959            let buffer_end =
 960                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
 961
 962            if start_region.excerpt.id == end_region.excerpt.id {
 963                if start_region.is_main_buffer {
 964                    edited_excerpt_ids.push(start_region.excerpt.id);
 965                    buffer_edits
 966                        .entry(start_region.buffer.remote_id())
 967                        .or_default()
 968                        .push(BufferEdit {
 969                            range: buffer_start..buffer_end,
 970                            new_text,
 971                            is_insertion: true,
 972                            original_indent_column,
 973                            excerpt_id: start_region.excerpt.id,
 974                        });
 975                }
 976            } else {
 977                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
 978                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
 979                if start_region.is_main_buffer {
 980                    edited_excerpt_ids.push(start_region.excerpt.id);
 981                    buffer_edits
 982                        .entry(start_region.buffer.remote_id())
 983                        .or_default()
 984                        .push(BufferEdit {
 985                            range: start_excerpt_range,
 986                            new_text: new_text.clone(),
 987                            is_insertion: true,
 988                            original_indent_column,
 989                            excerpt_id: start_region.excerpt.id,
 990                        });
 991                }
 992                if end_region.is_main_buffer {
 993                    edited_excerpt_ids.push(end_region.excerpt.id);
 994                    buffer_edits
 995                        .entry(end_region.buffer.remote_id())
 996                        .or_default()
 997                        .push(BufferEdit {
 998                            range: end_excerpt_range,
 999                            new_text: new_text.clone(),
1000                            is_insertion: false,
1001                            original_indent_column,
1002                            excerpt_id: end_region.excerpt.id,
1003                        });
1004                }
1005
1006                cursor.seek(&range.start);
1007                cursor.next_excerpt();
1008                while let Some(region) = cursor.region() {
1009                    if region.excerpt.id == end_region.excerpt.id {
1010                        break;
1011                    }
1012                    if region.is_main_buffer {
1013                        edited_excerpt_ids.push(region.excerpt.id);
1014                        buffer_edits
1015                            .entry(region.buffer.remote_id())
1016                            .or_default()
1017                            .push(BufferEdit {
1018                                range: region.buffer_range,
1019                                new_text: new_text.clone(),
1020                                is_insertion: false,
1021                                original_indent_column,
1022                                excerpt_id: region.excerpt.id,
1023                            });
1024                    }
1025                    cursor.next_excerpt();
1026                }
1027            }
1028        }
1029        (buffer_edits, edited_excerpt_ids)
1030    }
1031
1032    pub fn autoindent_ranges<I, S>(&self, ranges: I, cx: &mut Context<Self>)
1033    where
1034        I: IntoIterator<Item = Range<S>>,
1035        S: ToOffset,
1036    {
1037        let snapshot = self.read(cx);
1038        let empty = Arc::<str>::from("");
1039        let edits = ranges
1040            .into_iter()
1041            .map(|range| {
1042                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
1043                if range.start > range.end {
1044                    mem::swap(&mut range.start, &mut range.end);
1045                }
1046                (range, empty.clone())
1047            })
1048            .collect::<Vec<_>>();
1049
1050        return autoindent_ranges_internal(self, snapshot, edits, cx);
1051
1052        fn autoindent_ranges_internal(
1053            this: &MultiBuffer,
1054            snapshot: Ref<MultiBufferSnapshot>,
1055            edits: Vec<(Range<usize>, Arc<str>)>,
1056            cx: &mut Context<MultiBuffer>,
1057        ) {
1058            if this.read_only() || this.buffers.borrow().is_empty() {
1059                return;
1060            }
1061
1062            let (buffer_edits, edited_excerpt_ids) =
1063                this.convert_edits_to_buffer_edits(edits, &snapshot, &[]);
1064            drop(snapshot);
1065
1066            let mut buffer_ids = Vec::new();
1067            for (buffer_id, mut edits) in buffer_edits {
1068                buffer_ids.push(buffer_id);
1069                edits.sort_unstable_by_key(|edit| edit.range.start);
1070
1071                let mut ranges: Vec<Range<usize>> = Vec::new();
1072                for edit in edits {
1073                    if let Some(last_range) = ranges.last_mut()
1074                        && edit.range.start <= last_range.end
1075                    {
1076                        last_range.end = last_range.end.max(edit.range.end);
1077                        continue;
1078                    }
1079                    ranges.push(edit.range);
1080                }
1081
1082                this.buffers.borrow()[&buffer_id]
1083                    .buffer
1084                    .update(cx, |buffer, cx| {
1085                        buffer.autoindent_ranges(ranges, cx);
1086                    })
1087            }
1088
1089            cx.emit(Event::ExcerptsEdited {
1090                excerpt_ids: edited_excerpt_ids,
1091                buffer_ids,
1092            });
1093        }
1094    }
1095
1096    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
1097    // You can also request the insertion of empty lines above and below the line starting at the returned point.
1098    // Panics if the given position is invalid.
1099    pub fn insert_empty_line(
1100        &mut self,
1101        position: impl ToPoint,
1102        space_above: bool,
1103        space_below: bool,
1104        cx: &mut Context<Self>,
1105    ) -> Point {
1106        let multibuffer_point = position.to_point(&self.read(cx));
1107        let (buffer, buffer_point, _) = self.point_to_buffer_point(multibuffer_point, cx).unwrap();
1108        self.start_transaction(cx);
1109        let empty_line_start = buffer.update(cx, |buffer, cx| {
1110            buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
1111        });
1112        self.end_transaction(cx);
1113        multibuffer_point + (empty_line_start - buffer_point)
1114    }
1115
1116    pub fn start_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1117        self.start_transaction_at(Instant::now(), cx)
1118    }
1119
1120    pub fn start_transaction_at(
1121        &mut self,
1122        now: Instant,
1123        cx: &mut Context<Self>,
1124    ) -> Option<TransactionId> {
1125        if let Some(buffer) = self.as_singleton() {
1126            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1127        }
1128
1129        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1130            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1131        }
1132        self.history.start_transaction(now)
1133    }
1134
1135    pub fn last_transaction_id(&self, cx: &App) -> Option<TransactionId> {
1136        if let Some(buffer) = self.as_singleton() {
1137            buffer
1138                .read(cx)
1139                .peek_undo_stack()
1140                .map(|history_entry| history_entry.transaction_id())
1141        } else {
1142            let last_transaction = self.history.undo_stack.last()?;
1143            Some(last_transaction.id)
1144        }
1145    }
1146
1147    pub fn end_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1148        self.end_transaction_at(Instant::now(), cx)
1149    }
1150
1151    pub fn end_transaction_at(
1152        &mut self,
1153        now: Instant,
1154        cx: &mut Context<Self>,
1155    ) -> Option<TransactionId> {
1156        if let Some(buffer) = self.as_singleton() {
1157            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
1158        }
1159
1160        let mut buffer_transactions = HashMap::default();
1161        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1162            if let Some(transaction_id) =
1163                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
1164            {
1165                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
1166            }
1167        }
1168
1169        if self.history.end_transaction(now, buffer_transactions) {
1170            let transaction_id = self.history.group().unwrap();
1171            Some(transaction_id)
1172        } else {
1173            None
1174        }
1175    }
1176
1177    pub fn edited_ranges_for_transaction<D>(
1178        &self,
1179        transaction_id: TransactionId,
1180        cx: &App,
1181    ) -> Vec<Range<D>>
1182    where
1183        D: TextDimension + Ord + Sub<D, Output = D>,
1184    {
1185        let Some(transaction) = self.history.transaction(transaction_id) else {
1186            return Vec::new();
1187        };
1188
1189        let mut ranges = Vec::new();
1190        let snapshot = self.read(cx);
1191        let buffers = self.buffers.borrow();
1192        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(());
1193
1194        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
1195            let Some(buffer_state) = buffers.get(buffer_id) else {
1196                continue;
1197            };
1198
1199            let buffer = buffer_state.buffer.read(cx);
1200            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
1201                for excerpt_id in &buffer_state.excerpts {
1202                    cursor.seek(excerpt_id, Bias::Left);
1203                    if let Some(excerpt) = cursor.item()
1204                        && excerpt.locator == *excerpt_id
1205                    {
1206                        let excerpt_buffer_start = excerpt.range.context.start.summary::<D>(buffer);
1207                        let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
1208                        let excerpt_range = excerpt_buffer_start..excerpt_buffer_end;
1209                        if excerpt_range.contains(&range.start)
1210                            && excerpt_range.contains(&range.end)
1211                        {
1212                            let excerpt_start = D::from_text_summary(&cursor.start().text);
1213
1214                            let mut start = excerpt_start;
1215                            start.add_assign(&(range.start - excerpt_buffer_start));
1216                            let mut end = excerpt_start;
1217                            end.add_assign(&(range.end - excerpt_buffer_start));
1218
1219                            ranges.push(start..end);
1220                            break;
1221                        }
1222                    }
1223                }
1224            }
1225        }
1226
1227        ranges.sort_by_key(|range| range.start);
1228        ranges
1229    }
1230
1231    pub fn merge_transactions(
1232        &mut self,
1233        transaction: TransactionId,
1234        destination: TransactionId,
1235        cx: &mut Context<Self>,
1236    ) {
1237        if let Some(buffer) = self.as_singleton() {
1238            buffer.update(cx, |buffer, _| {
1239                buffer.merge_transactions(transaction, destination)
1240            });
1241        } else if let Some(transaction) = self.history.forget(transaction)
1242            && let Some(destination) = self.history.transaction_mut(destination)
1243        {
1244            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1245                if let Some(destination_buffer_transaction_id) =
1246                    destination.buffer_transactions.get(&buffer_id)
1247                {
1248                    if let Some(state) = self.buffers.borrow().get(&buffer_id) {
1249                        state.buffer.update(cx, |buffer, _| {
1250                            buffer.merge_transactions(
1251                                buffer_transaction_id,
1252                                *destination_buffer_transaction_id,
1253                            )
1254                        });
1255                    }
1256                } else {
1257                    destination
1258                        .buffer_transactions
1259                        .insert(buffer_id, buffer_transaction_id);
1260                }
1261            }
1262        }
1263    }
1264
1265    pub fn finalize_last_transaction(&mut self, cx: &mut Context<Self>) {
1266        self.history.finalize_last_transaction();
1267        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1268            buffer.update(cx, |buffer, _| {
1269                buffer.finalize_last_transaction();
1270            });
1271        }
1272    }
1273
1274    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &Context<Self>)
1275    where
1276        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
1277    {
1278        self.history
1279            .push_transaction(buffer_transactions, Instant::now(), cx);
1280        self.history.finalize_last_transaction();
1281    }
1282
1283    pub fn group_until_transaction(
1284        &mut self,
1285        transaction_id: TransactionId,
1286        cx: &mut Context<Self>,
1287    ) {
1288        if let Some(buffer) = self.as_singleton() {
1289            buffer.update(cx, |buffer, _| {
1290                buffer.group_until_transaction(transaction_id)
1291            });
1292        } else {
1293            self.history.group_until(transaction_id);
1294        }
1295    }
1296
1297    pub fn set_active_selections(
1298        &self,
1299        selections: &[Selection<Anchor>],
1300        line_mode: bool,
1301        cursor_shape: CursorShape,
1302        cx: &mut Context<Self>,
1303    ) {
1304        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1305            Default::default();
1306        let snapshot = self.read(cx);
1307        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1308        for selection in selections {
1309            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1310            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1311
1312            cursor.seek(&Some(start_locator), Bias::Left);
1313            while let Some(excerpt) = cursor.item()
1314                && excerpt.locator <= *end_locator
1315            {
1316                let mut start = excerpt.range.context.start;
1317                let mut end = excerpt.range.context.end;
1318                if excerpt.id == selection.start.excerpt_id {
1319                    start = selection.start.text_anchor;
1320                }
1321                if excerpt.id == selection.end.excerpt_id {
1322                    end = selection.end.text_anchor;
1323                }
1324                selections_by_buffer
1325                    .entry(excerpt.buffer_id)
1326                    .or_default()
1327                    .push(Selection {
1328                        id: selection.id,
1329                        start,
1330                        end,
1331                        reversed: selection.reversed,
1332                        goal: selection.goal,
1333                    });
1334
1335                cursor.next();
1336            }
1337        }
1338
1339        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1340            if !selections_by_buffer.contains_key(buffer_id) {
1341                buffer_state
1342                    .buffer
1343                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1344            }
1345        }
1346
1347        for (buffer_id, mut selections) in selections_by_buffer {
1348            self.buffers.borrow()[&buffer_id]
1349                .buffer
1350                .update(cx, |buffer, cx| {
1351                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1352                    let mut selections = selections.into_iter().peekable();
1353                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1354                        let mut selection = selections.next()?;
1355                        while let Some(next_selection) = selections.peek() {
1356                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1357                                let next_selection = selections.next().unwrap();
1358                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1359                                    selection.end = next_selection.end;
1360                                }
1361                            } else {
1362                                break;
1363                            }
1364                        }
1365                        Some(selection)
1366                    }));
1367                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1368                });
1369        }
1370    }
1371
1372    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1373        for buffer in self.buffers.borrow().values() {
1374            buffer
1375                .buffer
1376                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1377        }
1378    }
1379
1380    pub fn undo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1381        let mut transaction_id = None;
1382        if let Some(buffer) = self.as_singleton() {
1383            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1384        } else {
1385            while let Some(transaction) = self.history.pop_undo() {
1386                let mut undone = false;
1387                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1388                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1389                        undone |= buffer.update(cx, |buffer, cx| {
1390                            let undo_to = *buffer_transaction_id;
1391                            if let Some(entry) = buffer.peek_undo_stack() {
1392                                *buffer_transaction_id = entry.transaction_id();
1393                            }
1394                            buffer.undo_to_transaction(undo_to, cx)
1395                        });
1396                    }
1397                }
1398
1399                if undone {
1400                    transaction_id = Some(transaction.id);
1401                    break;
1402                }
1403            }
1404        }
1405
1406        if let Some(transaction_id) = transaction_id {
1407            cx.emit(Event::TransactionUndone { transaction_id });
1408        }
1409
1410        transaction_id
1411    }
1412
1413    pub fn redo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1414        if let Some(buffer) = self.as_singleton() {
1415            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1416        }
1417
1418        while let Some(transaction) = self.history.pop_redo() {
1419            let mut redone = false;
1420            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1421                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1422                    redone |= buffer.update(cx, |buffer, cx| {
1423                        let redo_to = *buffer_transaction_id;
1424                        if let Some(entry) = buffer.peek_redo_stack() {
1425                            *buffer_transaction_id = entry.transaction_id();
1426                        }
1427                        buffer.redo_to_transaction(redo_to, cx)
1428                    });
1429                }
1430            }
1431
1432            if redone {
1433                return Some(transaction.id);
1434            }
1435        }
1436
1437        None
1438    }
1439
1440    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1441        if let Some(buffer) = self.as_singleton() {
1442            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1443        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1444            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1445                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1446                    buffer.update(cx, |buffer, cx| {
1447                        buffer.undo_transaction(*transaction_id, cx)
1448                    });
1449                }
1450            }
1451        }
1452    }
1453
1454    pub fn forget_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1455        if let Some(buffer) = self.as_singleton() {
1456            buffer.update(cx, |buffer, _| {
1457                buffer.forget_transaction(transaction_id);
1458            });
1459        } else if let Some(transaction) = self.history.forget(transaction_id) {
1460            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1461                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1462                    state.buffer.update(cx, |buffer, _| {
1463                        buffer.forget_transaction(buffer_transaction_id);
1464                    });
1465                }
1466            }
1467        }
1468    }
1469
1470    pub fn push_excerpts<O>(
1471        &mut self,
1472        buffer: Entity<Buffer>,
1473        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1474        cx: &mut Context<Self>,
1475    ) -> Vec<ExcerptId>
1476    where
1477        O: text::ToOffset,
1478    {
1479        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1480    }
1481
1482    pub fn location_for_path(&self, path: &PathKey, cx: &App) -> Option<Anchor> {
1483        let excerpt_id = self.excerpts_by_path.get(path)?.first()?;
1484        let snapshot = self.snapshot(cx);
1485        let excerpt = snapshot.excerpt(*excerpt_id)?;
1486        Some(Anchor::in_buffer(
1487            *excerpt_id,
1488            excerpt.buffer_id,
1489            excerpt.range.context.start,
1490        ))
1491    }
1492
1493    pub fn excerpt_paths(&self) -> impl Iterator<Item = &PathKey> {
1494        self.excerpts_by_path.keys()
1495    }
1496
1497    fn expand_excerpts_with_paths(
1498        &mut self,
1499        ids: impl IntoIterator<Item = ExcerptId>,
1500        line_count: u32,
1501        direction: ExpandExcerptDirection,
1502        cx: &mut Context<Self>,
1503    ) {
1504        let grouped = ids
1505            .into_iter()
1506            .chunk_by(|id| self.paths_by_excerpt.get(id).cloned())
1507            .into_iter()
1508            .flat_map(|(k, v)| Some((k?, v.into_iter().collect::<Vec<_>>())))
1509            .collect::<Vec<_>>();
1510        let snapshot = self.snapshot(cx);
1511
1512        for (path, ids) in grouped.into_iter() {
1513            let Some(excerpt_ids) = self.excerpts_by_path.get(&path) else {
1514                continue;
1515            };
1516
1517            let ids_to_expand = HashSet::from_iter(ids);
1518            let expanded_ranges = excerpt_ids.iter().filter_map(|excerpt_id| {
1519                let excerpt = snapshot.excerpt(*excerpt_id)?;
1520
1521                let mut context = excerpt.range.context.to_point(&excerpt.buffer);
1522                if ids_to_expand.contains(excerpt_id) {
1523                    match direction {
1524                        ExpandExcerptDirection::Up => {
1525                            context.start.row = context.start.row.saturating_sub(line_count);
1526                            context.start.column = 0;
1527                        }
1528                        ExpandExcerptDirection::Down => {
1529                            context.end.row =
1530                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1531                            context.end.column = excerpt.buffer.line_len(context.end.row);
1532                        }
1533                        ExpandExcerptDirection::UpAndDown => {
1534                            context.start.row = context.start.row.saturating_sub(line_count);
1535                            context.start.column = 0;
1536                            context.end.row =
1537                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1538                            context.end.column = excerpt.buffer.line_len(context.end.row);
1539                        }
1540                    }
1541                }
1542
1543                Some(ExcerptRange {
1544                    context,
1545                    primary: excerpt.range.primary.to_point(&excerpt.buffer),
1546                })
1547            });
1548            let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1549            for range in expanded_ranges {
1550                if let Some(last_range) = merged_ranges.last_mut()
1551                    && last_range.context.end >= range.context.start
1552                {
1553                    last_range.context.end = range.context.end;
1554                    continue;
1555                }
1556                merged_ranges.push(range)
1557            }
1558            let Some(excerpt_id) = excerpt_ids.first() else {
1559                continue;
1560            };
1561            let Some(buffer_id) = &snapshot.buffer_id_for_excerpt(*excerpt_id) else {
1562                continue;
1563            };
1564
1565            let Some(buffer) = self
1566                .buffers
1567                .borrow()
1568                .get(buffer_id)
1569                .map(|b| b.buffer.clone())
1570            else {
1571                continue;
1572            };
1573
1574            let buffer_snapshot = buffer.read(cx).snapshot();
1575            self.update_path_excerpts(path.clone(), buffer, &buffer_snapshot, merged_ranges, cx);
1576        }
1577    }
1578
1579    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1580    pub fn set_excerpts_for_path(
1581        &mut self,
1582        path: PathKey,
1583        buffer: Entity<Buffer>,
1584        ranges: impl IntoIterator<Item = Range<Point>>,
1585        context_line_count: u32,
1586        cx: &mut Context<Self>,
1587    ) -> (Vec<Range<Anchor>>, bool) {
1588        let buffer_snapshot = buffer.read(cx).snapshot();
1589        let excerpt_ranges = build_excerpt_ranges(ranges, context_line_count, &buffer_snapshot);
1590
1591        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1592        self.set_merged_excerpt_ranges_for_path(
1593            path,
1594            buffer,
1595            excerpt_ranges,
1596            &buffer_snapshot,
1597            new,
1598            counts,
1599            cx,
1600        )
1601    }
1602
1603    pub fn set_excerpt_ranges_for_path(
1604        &mut self,
1605        path: PathKey,
1606        buffer: Entity<Buffer>,
1607        buffer_snapshot: &BufferSnapshot,
1608        excerpt_ranges: Vec<ExcerptRange<Point>>,
1609        cx: &mut Context<Self>,
1610    ) -> (Vec<Range<Anchor>>, bool) {
1611        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1612        self.set_merged_excerpt_ranges_for_path(
1613            path,
1614            buffer,
1615            excerpt_ranges,
1616            buffer_snapshot,
1617            new,
1618            counts,
1619            cx,
1620        )
1621    }
1622
1623    pub fn set_anchored_excerpts_for_path(
1624        &self,
1625        buffer: Entity<Buffer>,
1626        ranges: Vec<Range<text::Anchor>>,
1627        context_line_count: u32,
1628        cx: &mut Context<Self>,
1629    ) -> Task<Vec<Range<Anchor>>> {
1630        let buffer_snapshot = buffer.read(cx).snapshot();
1631        let path_key = PathKey::for_buffer(&buffer, cx);
1632        cx.spawn(async move |multi_buffer, cx| {
1633            let snapshot = buffer_snapshot.clone();
1634            let (excerpt_ranges, new, counts) = cx
1635                .background_spawn(async move {
1636                    let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
1637                    let excerpt_ranges =
1638                        build_excerpt_ranges(ranges, context_line_count, &snapshot);
1639                    let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1640                    (excerpt_ranges, new, counts)
1641                })
1642                .await;
1643
1644            multi_buffer
1645                .update(cx, move |multi_buffer, cx| {
1646                    let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
1647                        path_key,
1648                        buffer,
1649                        excerpt_ranges,
1650                        &buffer_snapshot,
1651                        new,
1652                        counts,
1653                        cx,
1654                    );
1655                    ranges
1656                })
1657                .ok()
1658                .unwrap_or_default()
1659        })
1660    }
1661
1662    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1663    fn set_merged_excerpt_ranges_for_path(
1664        &mut self,
1665        path: PathKey,
1666        buffer: Entity<Buffer>,
1667        ranges: Vec<ExcerptRange<Point>>,
1668        buffer_snapshot: &BufferSnapshot,
1669        new: Vec<ExcerptRange<Point>>,
1670        counts: Vec<usize>,
1671        cx: &mut Context<Self>,
1672    ) -> (Vec<Range<Anchor>>, bool) {
1673        let (excerpt_ids, added_a_new_excerpt) =
1674            self.update_path_excerpts(path, buffer, buffer_snapshot, new, cx);
1675
1676        let mut result = Vec::new();
1677        let mut ranges = ranges.into_iter();
1678        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(counts.into_iter()) {
1679            for range in ranges.by_ref().take(range_count) {
1680                let range = Anchor::range_in_buffer(
1681                    excerpt_id,
1682                    buffer_snapshot.remote_id(),
1683                    buffer_snapshot.anchor_before(&range.primary.start)
1684                        ..buffer_snapshot.anchor_after(&range.primary.end),
1685                );
1686                result.push(range)
1687            }
1688        }
1689        (result, added_a_new_excerpt)
1690    }
1691
1692    fn merge_excerpt_ranges<'a>(
1693        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1694    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1695        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1696        let mut counts: Vec<usize> = Vec::new();
1697        for range in expanded_ranges {
1698            if let Some(last_range) = merged_ranges.last_mut() {
1699                debug_assert!(
1700                    last_range.context.start <= range.context.start,
1701                    "Last range: {last_range:?} Range: {range:?}"
1702                );
1703                if last_range.context.end >= range.context.start
1704                    || last_range.context.end.row + 1 == range.context.start.row
1705                {
1706                    last_range.context.end = range.context.end.max(last_range.context.end);
1707                    *counts.last_mut().unwrap() += 1;
1708                    continue;
1709                }
1710            }
1711            merged_ranges.push(range.clone());
1712            counts.push(1);
1713        }
1714        (merged_ranges, counts)
1715    }
1716
1717    fn update_path_excerpts(
1718        &mut self,
1719        path: PathKey,
1720        buffer: Entity<Buffer>,
1721        buffer_snapshot: &BufferSnapshot,
1722        new: Vec<ExcerptRange<Point>>,
1723        cx: &mut Context<Self>,
1724    ) -> (Vec<ExcerptId>, bool) {
1725        let mut insert_after = self
1726            .excerpts_by_path
1727            .range(..path.clone())
1728            .next_back()
1729            .map(|(_, value)| *value.last().unwrap())
1730            .unwrap_or(ExcerptId::min());
1731
1732        let existing = self
1733            .excerpts_by_path
1734            .get(&path)
1735            .cloned()
1736            .unwrap_or_default();
1737
1738        let mut new_iter = new.into_iter().peekable();
1739        let mut existing_iter = existing.into_iter().peekable();
1740
1741        let mut excerpt_ids = Vec::new();
1742        let mut to_remove = Vec::new();
1743        let mut to_insert: Vec<(ExcerptId, ExcerptRange<Point>)> = Vec::new();
1744        let mut added_a_new_excerpt = false;
1745        let snapshot = self.snapshot(cx);
1746
1747        let mut next_excerpt_id =
1748            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1749                last_entry.id.0 + 1
1750            } else {
1751                1
1752            };
1753
1754        let mut next_excerpt_id = move || ExcerptId(post_inc(&mut next_excerpt_id));
1755
1756        let mut excerpts_cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1757        excerpts_cursor.next();
1758
1759        loop {
1760            let new = new_iter.peek();
1761            let existing = if let Some(existing_id) = existing_iter.peek() {
1762                let locator = snapshot.excerpt_locator_for_id(*existing_id);
1763                excerpts_cursor.seek_forward(&Some(locator), Bias::Left);
1764                if let Some(excerpt) = excerpts_cursor.item() {
1765                    if excerpt.buffer_id != buffer_snapshot.remote_id() {
1766                        to_remove.push(*existing_id);
1767                        existing_iter.next();
1768                        continue;
1769                    }
1770                    Some((
1771                        *existing_id,
1772                        excerpt.range.context.to_point(buffer_snapshot),
1773                    ))
1774                } else {
1775                    None
1776                }
1777            } else {
1778                None
1779            };
1780
1781            if let Some((last_id, last)) = to_insert.last_mut() {
1782                if let Some(new) = new
1783                    && last.context.end >= new.context.start
1784                {
1785                    last.context.end = last.context.end.max(new.context.end);
1786                    excerpt_ids.push(*last_id);
1787                    new_iter.next();
1788                    continue;
1789                }
1790                if let Some((existing_id, existing_range)) = &existing
1791                    && last.context.end >= existing_range.start
1792                {
1793                    last.context.end = last.context.end.max(existing_range.end);
1794                    to_remove.push(*existing_id);
1795                    self.snapshot
1796                        .borrow_mut()
1797                        .replaced_excerpts
1798                        .insert(*existing_id, *last_id);
1799                    existing_iter.next();
1800                    continue;
1801                }
1802            }
1803
1804            match (new, existing) {
1805                (None, None) => break,
1806                (None, Some((existing_id, _))) => {
1807                    existing_iter.next();
1808                    to_remove.push(existing_id);
1809                    continue;
1810                }
1811                (Some(_), None) => {
1812                    added_a_new_excerpt = true;
1813                    let new_id = next_excerpt_id();
1814                    excerpt_ids.push(new_id);
1815                    to_insert.push((new_id, new_iter.next().unwrap()));
1816                    continue;
1817                }
1818                (Some(new), Some((_, existing_range))) => {
1819                    if existing_range.end < new.context.start {
1820                        let existing_id = existing_iter.next().unwrap();
1821                        to_remove.push(existing_id);
1822                        continue;
1823                    } else if existing_range.start > new.context.end {
1824                        let new_id = next_excerpt_id();
1825                        excerpt_ids.push(new_id);
1826                        to_insert.push((new_id, new_iter.next().unwrap()));
1827                        continue;
1828                    }
1829
1830                    if existing_range.start == new.context.start
1831                        && existing_range.end == new.context.end
1832                    {
1833                        self.insert_excerpts_with_ids_after(
1834                            insert_after,
1835                            buffer.clone(),
1836                            mem::take(&mut to_insert),
1837                            cx,
1838                        );
1839                        insert_after = existing_iter.next().unwrap();
1840                        excerpt_ids.push(insert_after);
1841                        new_iter.next();
1842                    } else {
1843                        let existing_id = existing_iter.next().unwrap();
1844                        let new_id = next_excerpt_id();
1845                        self.snapshot
1846                            .borrow_mut()
1847                            .replaced_excerpts
1848                            .insert(existing_id, new_id);
1849                        to_remove.push(existing_id);
1850                        let mut range = new_iter.next().unwrap();
1851                        range.context.start = range.context.start.min(existing_range.start);
1852                        range.context.end = range.context.end.max(existing_range.end);
1853                        excerpt_ids.push(new_id);
1854                        to_insert.push((new_id, range));
1855                    }
1856                }
1857            };
1858        }
1859
1860        self.insert_excerpts_with_ids_after(insert_after, buffer, to_insert, cx);
1861        self.remove_excerpts(to_remove, cx);
1862        if excerpt_ids.is_empty() {
1863            self.excerpts_by_path.remove(&path);
1864        } else {
1865            for excerpt_id in &excerpt_ids {
1866                self.paths_by_excerpt.insert(*excerpt_id, path.clone());
1867            }
1868            self.excerpts_by_path
1869                .insert(path, excerpt_ids.iter().dedup().cloned().collect());
1870        }
1871
1872        (excerpt_ids, added_a_new_excerpt)
1873    }
1874
1875    pub fn paths(&self) -> impl Iterator<Item = PathKey> + '_ {
1876        self.excerpts_by_path.keys().cloned()
1877    }
1878
1879    pub fn remove_excerpts_for_path(&mut self, path: PathKey, cx: &mut Context<Self>) {
1880        if let Some(to_remove) = self.excerpts_by_path.remove(&path) {
1881            self.remove_excerpts(to_remove, cx)
1882        }
1883    }
1884
1885    pub fn insert_excerpts_after<O>(
1886        &mut self,
1887        prev_excerpt_id: ExcerptId,
1888        buffer: Entity<Buffer>,
1889        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1890        cx: &mut Context<Self>,
1891    ) -> Vec<ExcerptId>
1892    where
1893        O: text::ToOffset,
1894    {
1895        let mut ids = Vec::new();
1896        let mut next_excerpt_id =
1897            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1898                last_entry.id.0 + 1
1899            } else {
1900                1
1901            };
1902        self.insert_excerpts_with_ids_after(
1903            prev_excerpt_id,
1904            buffer,
1905            ranges.into_iter().map(|range| {
1906                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1907                ids.push(id);
1908                (id, range)
1909            }),
1910            cx,
1911        );
1912        ids
1913    }
1914
1915    pub fn insert_excerpts_with_ids_after<O>(
1916        &mut self,
1917        prev_excerpt_id: ExcerptId,
1918        buffer: Entity<Buffer>,
1919        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1920        cx: &mut Context<Self>,
1921    ) where
1922        O: text::ToOffset,
1923    {
1924        assert_eq!(self.history.transaction_depth, 0);
1925        let mut ranges = ranges.into_iter().peekable();
1926        if ranges.peek().is_none() {
1927            return Default::default();
1928        }
1929
1930        self.sync(cx);
1931
1932        let buffer_snapshot = buffer.read(cx).snapshot();
1933        let buffer_id = buffer_snapshot.remote_id();
1934
1935        let mut buffers = self.buffers.borrow_mut();
1936        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| {
1937            self.buffer_changed_since_sync.replace(true);
1938            buffer.update(cx, |buffer, _| {
1939                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1940            });
1941            BufferState {
1942                last_version: buffer_snapshot.version().clone(),
1943                last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1944                excerpts: Default::default(),
1945                _subscriptions: [
1946                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1947                    cx.subscribe(&buffer, Self::on_buffer_event),
1948                ],
1949                buffer: buffer.clone(),
1950            }
1951        });
1952
1953        let mut snapshot = self.snapshot.borrow_mut();
1954
1955        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1956        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1957        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1958        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1959        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1960
1961        let edit_start = ExcerptOffset::new(new_excerpts.summary().text.len);
1962        new_excerpts.update_last(
1963            |excerpt| {
1964                excerpt.has_trailing_newline = true;
1965            },
1966            (),
1967        );
1968
1969        let next_locator = if let Some(excerpt) = cursor.item() {
1970            excerpt.locator.clone()
1971        } else {
1972            Locator::max()
1973        };
1974
1975        let mut excerpts = Vec::new();
1976        while let Some((id, range)) = ranges.next() {
1977            let locator = Locator::between(&prev_locator, &next_locator);
1978            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1979                buffer_state.excerpts.insert(ix, locator.clone());
1980            }
1981            let range = ExcerptRange {
1982                context: buffer_snapshot.anchor_before(&range.context.start)
1983                    ..buffer_snapshot.anchor_after(&range.context.end),
1984                primary: buffer_snapshot.anchor_before(&range.primary.start)
1985                    ..buffer_snapshot.anchor_after(&range.primary.end),
1986            };
1987            excerpts.push((id, range.clone()));
1988            let excerpt = Excerpt::new(
1989                id,
1990                locator.clone(),
1991                buffer_id,
1992                buffer_snapshot.clone(),
1993                range,
1994                ranges.peek().is_some() || cursor.item().is_some(),
1995            );
1996            new_excerpts.push(excerpt, ());
1997            prev_locator = locator.clone();
1998
1999            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
2000                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
2001            }
2002            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
2003        }
2004
2005        let edit_end = ExcerptOffset::new(new_excerpts.summary().text.len);
2006
2007        let suffix = cursor.suffix();
2008        let changed_trailing_excerpt = suffix.is_empty();
2009        new_excerpts.append(suffix, ());
2010        drop(cursor);
2011        snapshot.excerpts = new_excerpts;
2012        snapshot.excerpt_ids = new_excerpt_ids;
2013        if changed_trailing_excerpt {
2014            snapshot.trailing_excerpt_update_count += 1;
2015        }
2016
2017        self.sync_diff_transforms(
2018            &mut snapshot,
2019            vec![Edit {
2020                old: edit_start..edit_start,
2021                new: edit_start..edit_end,
2022            }],
2023            DiffChangeKind::BufferEdited,
2024        );
2025        cx.emit(Event::Edited {
2026            singleton_buffer_edited: false,
2027            edited_buffer: None,
2028        });
2029        cx.emit(Event::ExcerptsAdded {
2030            buffer,
2031            predecessor: prev_excerpt_id,
2032            excerpts,
2033        });
2034        cx.notify();
2035    }
2036
2037    pub fn clear(&mut self, cx: &mut Context<Self>) {
2038        self.sync(cx);
2039        let ids = self.excerpt_ids();
2040        let removed_buffer_ids = self
2041            .buffers
2042            .borrow_mut()
2043            .drain()
2044            .map(|(id, _)| id)
2045            .collect();
2046        self.excerpts_by_path.clear();
2047        self.paths_by_excerpt.clear();
2048        let mut snapshot = self.snapshot.borrow_mut();
2049        let start = ExcerptOffset::new(0);
2050        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2051        snapshot.excerpts = Default::default();
2052        snapshot.trailing_excerpt_update_count += 1;
2053        snapshot.is_dirty = false;
2054        snapshot.has_deleted_file = false;
2055        snapshot.has_conflict = false;
2056        snapshot.replaced_excerpts.clear();
2057
2058        self.sync_diff_transforms(
2059            &mut snapshot,
2060            vec![Edit {
2061                old: start..prev_len,
2062                new: start..start,
2063            }],
2064            DiffChangeKind::BufferEdited,
2065        );
2066        cx.emit(Event::Edited {
2067            singleton_buffer_edited: false,
2068            edited_buffer: None,
2069        });
2070        cx.emit(Event::ExcerptsRemoved {
2071            ids,
2072            removed_buffer_ids,
2073        });
2074        cx.notify();
2075    }
2076
2077    pub fn excerpts_for_buffer(
2078        &self,
2079        buffer_id: BufferId,
2080        cx: &App,
2081    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2082        let mut excerpts = Vec::new();
2083        let snapshot = self.read(cx);
2084        let buffers = self.buffers.borrow();
2085        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
2086        if let Some(locators) = buffers.get(&buffer_id).map(|state| &state.excerpts) {
2087            for locator in locators {
2088                cursor.seek_forward(&Some(locator), Bias::Left);
2089                if let Some(excerpt) = cursor.item()
2090                    && excerpt.locator == *locator
2091                {
2092                    excerpts.push((excerpt.id, excerpt.range.clone()));
2093                }
2094            }
2095        }
2096
2097        excerpts
2098    }
2099
2100    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2101        let snapshot = self.read(cx);
2102        let buffers = self.buffers.borrow();
2103        let mut excerpts = snapshot
2104            .excerpts
2105            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
2106        let mut diff_transforms = snapshot
2107            .diff_transforms
2108            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
2109        diff_transforms.next();
2110        let locators = buffers
2111            .get(&buffer_id)
2112            .into_iter()
2113            .flat_map(|state| &state.excerpts);
2114        let mut result = Vec::new();
2115        for locator in locators {
2116            excerpts.seek_forward(&Some(locator), Bias::Left);
2117            if let Some(excerpt) = excerpts.item()
2118                && excerpt.locator == *locator
2119            {
2120                let excerpt_start = excerpts.start().1.clone();
2121                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2122
2123                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2124                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2125                let start = diff_transforms.start().1.0 + overshoot;
2126
2127                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2128                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2129                let end = diff_transforms.start().1.0 + overshoot;
2130
2131                result.push(start..end)
2132            }
2133        }
2134        result
2135    }
2136
2137    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2138        self.snapshot
2139            .borrow()
2140            .excerpts
2141            .iter()
2142            .map(|entry| entry.buffer_id)
2143            .collect()
2144    }
2145
2146    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2147        self.snapshot
2148            .borrow()
2149            .excerpts
2150            .iter()
2151            .map(|entry| entry.id)
2152            .collect()
2153    }
2154
2155    pub fn excerpt_containing(
2156        &self,
2157        position: impl ToOffset,
2158        cx: &App,
2159    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2160        let snapshot = self.read(cx);
2161        let offset = position.to_offset(&snapshot);
2162
2163        let mut cursor = snapshot.cursor::<usize>();
2164        cursor.seek(&offset);
2165        cursor
2166            .excerpt()
2167            .or_else(|| snapshot.excerpts.last())
2168            .map(|excerpt| {
2169                (
2170                    excerpt.id,
2171                    self.buffers
2172                        .borrow()
2173                        .get(&excerpt.buffer_id)
2174                        .unwrap()
2175                        .buffer
2176                        .clone(),
2177                    excerpt.range.context.clone(),
2178                )
2179            })
2180    }
2181
2182    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2183        if let Some(buffer_id) = anchor.buffer_id {
2184            self.buffer(buffer_id)
2185        } else {
2186            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2187            Some(buffer)
2188        }
2189    }
2190
2191    // If point is at the end of the buffer, the last excerpt is returned
2192    pub fn point_to_buffer_offset<T: ToOffset>(
2193        &self,
2194        point: T,
2195        cx: &App,
2196    ) -> Option<(Entity<Buffer>, usize)> {
2197        let snapshot = self.read(cx);
2198        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2199        Some((
2200            self.buffers
2201                .borrow()
2202                .get(&buffer.remote_id())?
2203                .buffer
2204                .clone(),
2205            offset,
2206        ))
2207    }
2208
2209    // If point is at the end of the buffer, the last excerpt is returned
2210    pub fn point_to_buffer_point<T: ToPoint>(
2211        &self,
2212        point: T,
2213        cx: &App,
2214    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2215        let snapshot = self.read(cx);
2216        let (buffer, point, is_main_buffer) =
2217            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2218        Some((
2219            self.buffers
2220                .borrow()
2221                .get(&buffer.remote_id())?
2222                .buffer
2223                .clone(),
2224            point,
2225            is_main_buffer,
2226        ))
2227    }
2228
2229    pub fn buffer_point_to_anchor(
2230        &self,
2231        buffer: &Entity<Buffer>,
2232        point: Point,
2233        cx: &App,
2234    ) -> Option<Anchor> {
2235        let mut found = None;
2236        let snapshot = buffer.read(cx).snapshot();
2237        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2238            let start = range.context.start.to_point(&snapshot);
2239            let end = range.context.end.to_point(&snapshot);
2240            if start <= point && point < end {
2241                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2242                break;
2243            }
2244            if point < start {
2245                found = Some((start, excerpt_id));
2246            }
2247            if point > end {
2248                found = Some((end, excerpt_id));
2249            }
2250        }
2251
2252        found.map(|(point, excerpt_id)| {
2253            let text_anchor = snapshot.anchor_after(point);
2254            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2255        })
2256    }
2257
2258    pub fn remove_excerpts(
2259        &mut self,
2260        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2261        cx: &mut Context<Self>,
2262    ) {
2263        self.sync(cx);
2264        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2265        if ids.is_empty() {
2266            return;
2267        }
2268
2269        let mut buffers = self.buffers.borrow_mut();
2270        let mut snapshot = self.snapshot.borrow_mut();
2271        let mut new_excerpts = SumTree::default();
2272        let mut cursor = snapshot
2273            .excerpts
2274            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2275        let mut edits = Vec::new();
2276        let mut excerpt_ids = ids.iter().copied().peekable();
2277        let mut removed_buffer_ids = Vec::new();
2278
2279        while let Some(excerpt_id) = excerpt_ids.next() {
2280            self.paths_by_excerpt.remove(&excerpt_id);
2281            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2282            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2283            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2284
2285            if let Some(mut excerpt) = cursor.item() {
2286                if excerpt.id != excerpt_id {
2287                    continue;
2288                }
2289                let mut old_start = cursor.start().1;
2290
2291                // Skip over the removed excerpt.
2292                'remove_excerpts: loop {
2293                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2294                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2295                        if buffer_state.excerpts.is_empty() {
2296                            log::debug!(
2297                                "removing buffer and diff for buffer {}",
2298                                excerpt.buffer_id
2299                            );
2300                            buffers.remove(&excerpt.buffer_id);
2301                            removed_buffer_ids.push(excerpt.buffer_id);
2302                        }
2303                    }
2304                    cursor.next();
2305
2306                    // Skip over any subsequent excerpts that are also removed.
2307                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2308                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2309                        if let Some(next_excerpt) = cursor.item()
2310                            && next_excerpt.locator == *next_locator
2311                        {
2312                            excerpt_ids.next();
2313                            excerpt = next_excerpt;
2314                            continue 'remove_excerpts;
2315                        }
2316                    }
2317
2318                    break;
2319                }
2320
2321                // When removing the last excerpt, remove the trailing newline from
2322                // the previous excerpt.
2323                if cursor.item().is_none() && old_start.value > 0 {
2324                    old_start.value -= 1;
2325                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2326                }
2327
2328                // Push an edit for the removal of this run of excerpts.
2329                let old_end = cursor.start().1;
2330                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2331                edits.push(Edit {
2332                    old: old_start..old_end,
2333                    new: new_start..new_start,
2334                });
2335            }
2336        }
2337        let suffix = cursor.suffix();
2338        let changed_trailing_excerpt = suffix.is_empty();
2339        new_excerpts.append(suffix, ());
2340        drop(cursor);
2341        snapshot.excerpts = new_excerpts;
2342        for buffer_id in &removed_buffer_ids {
2343            self.diffs.remove(buffer_id);
2344            snapshot.diffs.remove(buffer_id);
2345        }
2346
2347        if changed_trailing_excerpt {
2348            snapshot.trailing_excerpt_update_count += 1;
2349        }
2350
2351        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2352        self.buffer_changed_since_sync.replace(true);
2353        cx.emit(Event::Edited {
2354            singleton_buffer_edited: false,
2355            edited_buffer: None,
2356        });
2357        cx.emit(Event::ExcerptsRemoved {
2358            ids,
2359            removed_buffer_ids,
2360        });
2361        cx.notify();
2362    }
2363
2364    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2365        &self,
2366        anchors: Anchors,
2367        cx: &mut Context<Self>,
2368    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2369        let borrow = self.buffers.borrow();
2370        let mut error = None;
2371        let mut futures = Vec::new();
2372        for anchor in anchors {
2373            if let Some(buffer_id) = anchor.buffer_id {
2374                if let Some(buffer) = borrow.get(&buffer_id) {
2375                    buffer.buffer.update(cx, |buffer, _| {
2376                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2377                    });
2378                } else {
2379                    error = Some(anyhow!(
2380                        "buffer {buffer_id} is not part of this multi-buffer"
2381                    ));
2382                    break;
2383                }
2384            }
2385        }
2386        async move {
2387            if let Some(error) = error {
2388                Err(error)?;
2389            }
2390            for future in futures {
2391                future.await?;
2392            }
2393            Ok(())
2394        }
2395    }
2396
2397    pub fn text_anchor_for_position<T: ToOffset>(
2398        &self,
2399        position: T,
2400        cx: &App,
2401    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2402        let snapshot = self.read(cx);
2403        let anchor = snapshot.anchor_before(position);
2404        let buffer = self
2405            .buffers
2406            .borrow()
2407            .get(&anchor.buffer_id?)?
2408            .buffer
2409            .clone();
2410        Some((buffer, anchor.text_anchor))
2411    }
2412
2413    fn on_buffer_event(
2414        &mut self,
2415        buffer: Entity<Buffer>,
2416        event: &language::BufferEvent,
2417        cx: &mut Context<Self>,
2418    ) {
2419        use language::BufferEvent;
2420        cx.emit(match event {
2421            BufferEvent::Edited => Event::Edited {
2422                singleton_buffer_edited: true,
2423                edited_buffer: Some(buffer),
2424            },
2425            BufferEvent::DirtyChanged => Event::DirtyChanged,
2426            BufferEvent::Saved => Event::Saved,
2427            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2428            BufferEvent::Reloaded => Event::Reloaded,
2429            BufferEvent::LanguageChanged => Event::LanguageChanged(buffer.read(cx).remote_id()),
2430            BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2431            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2432            BufferEvent::CapabilityChanged => {
2433                self.capability = buffer.read(cx).capability();
2434                return;
2435            }
2436            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2437        });
2438    }
2439
2440    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2441        self.sync(cx);
2442        let mut snapshot = self.snapshot.borrow_mut();
2443        let diff = diff.read(cx);
2444        let buffer_id = diff.buffer_id;
2445        let diff = diff.snapshot(cx);
2446        snapshot.diffs.insert(buffer_id, diff);
2447    }
2448
2449    fn buffer_diff_changed(
2450        &mut self,
2451        diff: Entity<BufferDiff>,
2452        range: Range<text::Anchor>,
2453        cx: &mut Context<Self>,
2454    ) {
2455        self.sync(cx);
2456        self.buffer_changed_since_sync.replace(true);
2457
2458        let diff = diff.read(cx);
2459        let buffer_id = diff.buffer_id;
2460        let buffers = self.buffers.borrow();
2461        let Some(buffer_state) = buffers.get(&buffer_id) else {
2462            return;
2463        };
2464
2465        let buffer = buffer_state.buffer.read(cx);
2466        let diff_change_range = range.to_offset(buffer);
2467
2468        let new_diff = diff.snapshot(cx);
2469        let mut snapshot = self.snapshot.borrow_mut();
2470        let base_text_changed = snapshot
2471            .diffs
2472            .get(&buffer_id)
2473            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2474
2475        snapshot.diffs.insert(buffer_id, new_diff);
2476
2477        let mut excerpt_edits = Vec::new();
2478        for locator in &buffer_state.excerpts {
2479            let mut cursor = snapshot
2480                .excerpts
2481                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2482            cursor.seek_forward(&Some(locator), Bias::Left);
2483            if let Some(excerpt) = cursor.item()
2484                && excerpt.locator == *locator
2485            {
2486                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2487                if diff_change_range.end < excerpt_buffer_range.start
2488                    || diff_change_range.start > excerpt_buffer_range.end
2489                {
2490                    continue;
2491                }
2492                let excerpt_start = cursor.start().1;
2493                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2494                let diff_change_start_in_excerpt = ExcerptOffset::new(
2495                    diff_change_range
2496                        .start
2497                        .saturating_sub(excerpt_buffer_range.start),
2498                );
2499                let diff_change_end_in_excerpt = ExcerptOffset::new(
2500                    diff_change_range
2501                        .end
2502                        .saturating_sub(excerpt_buffer_range.start),
2503                );
2504                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2505                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2506                excerpt_edits.push(Edit {
2507                    old: edit_start..edit_end,
2508                    new: edit_start..edit_end,
2509                });
2510            }
2511        }
2512
2513        self.sync_diff_transforms(
2514            &mut snapshot,
2515            excerpt_edits,
2516            DiffChangeKind::DiffUpdated {
2517                base_changed: base_text_changed,
2518            },
2519        );
2520        cx.emit(Event::Edited {
2521            singleton_buffer_edited: false,
2522            edited_buffer: None,
2523        });
2524    }
2525
2526    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2527        self.buffers
2528            .borrow()
2529            .values()
2530            .map(|state| state.buffer.clone())
2531            .collect()
2532    }
2533
2534    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2535        self.buffers.borrow().keys().copied().collect()
2536    }
2537
2538    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2539        self.buffers
2540            .borrow()
2541            .get(&buffer_id)
2542            .map(|state| state.buffer.clone())
2543    }
2544
2545    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2546        self.point_to_buffer_offset(point, cx)
2547            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2548    }
2549
2550    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2551        let buffer_id = self
2552            .snapshot
2553            .borrow()
2554            .excerpts
2555            .first()
2556            .map(|excerpt| excerpt.buffer.remote_id());
2557        buffer_id
2558            .and_then(|buffer_id| self.buffer(buffer_id))
2559            .map(|buffer| {
2560                let buffer = buffer.read(cx);
2561                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2562            })
2563            .unwrap_or_else(move || self.language_settings_at(0, cx))
2564    }
2565
2566    pub fn language_settings_at<'a, T: ToOffset>(
2567        &'a self,
2568        point: T,
2569        cx: &'a App,
2570    ) -> Cow<'a, LanguageSettings> {
2571        let mut language = None;
2572        let mut file = None;
2573        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2574            let buffer = buffer.read(cx);
2575            language = buffer.language_at(offset);
2576            file = buffer.file();
2577        }
2578        language_settings(language.map(|l| l.name()), file, cx)
2579    }
2580
2581    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2582        self.buffers
2583            .borrow()
2584            .values()
2585            .for_each(|state| f(&state.buffer))
2586    }
2587
2588    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2589        if let Some(title) = self.title.as_ref() {
2590            return title.into();
2591        }
2592
2593        if let Some(buffer) = self.as_singleton() {
2594            let buffer = buffer.read(cx);
2595
2596            if let Some(file) = buffer.file() {
2597                return file.file_name(cx).into();
2598            }
2599
2600            if let Some(title) = self.buffer_content_title(buffer) {
2601                return title;
2602            }
2603        };
2604
2605        "untitled".into()
2606    }
2607
2608    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2609        let mut is_leading_whitespace = true;
2610        let mut count = 0;
2611        let mut prev_was_space = false;
2612        let mut title = String::new();
2613
2614        for ch in buffer.snapshot().chars() {
2615            if is_leading_whitespace && ch.is_whitespace() {
2616                continue;
2617            }
2618
2619            is_leading_whitespace = false;
2620
2621            if ch == '\n' || count >= 40 {
2622                break;
2623            }
2624
2625            if ch.is_whitespace() {
2626                if !prev_was_space {
2627                    title.push(' ');
2628                    count += 1;
2629                    prev_was_space = true;
2630                }
2631            } else {
2632                title.push(ch);
2633                count += 1;
2634                prev_was_space = false;
2635            }
2636        }
2637
2638        let title = title.trim_end().to_string();
2639
2640        if title.is_empty() {
2641            return None;
2642        }
2643
2644        Some(title.into())
2645    }
2646
2647    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2648        self.title = Some(title);
2649        cx.notify();
2650    }
2651
2652    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2653    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2654        for buffer_state in self.buffers.borrow().values() {
2655            buffer_state
2656                .buffer
2657                .update(cx, |buffer, _cx| buffer.refresh_preview());
2658        }
2659    }
2660
2661    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2662    pub fn preserve_preview(&self, cx: &App) -> bool {
2663        self.buffers
2664            .borrow()
2665            .values()
2666            .all(|state| state.buffer.read(cx).preserve_preview())
2667    }
2668
2669    #[cfg(any(test, feature = "test-support"))]
2670    pub fn is_parsing(&self, cx: &App) -> bool {
2671        self.as_singleton().unwrap().read(cx).is_parsing()
2672    }
2673
2674    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2675        let buffer_id = diff.read(cx).buffer_id;
2676        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2677        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2678    }
2679
2680    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2681        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2682    }
2683
2684    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2685        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2686    }
2687
2688    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2689        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2690    }
2691
2692    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2693        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2694        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2695    }
2696
2697    pub fn all_diff_hunks_expanded(&self) -> bool {
2698        self.snapshot.borrow().all_diff_hunks_expanded
2699    }
2700
2701    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2702        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2703        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2704    }
2705
2706    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2707        self.read(cx)
2708            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2709            .nth(1)
2710            .is_some()
2711    }
2712
2713    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2714        let snapshot = self.read(cx);
2715        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2716        let offset_range = range.to_offset(&snapshot);
2717        cursor.seek(&offset_range.start, Bias::Left);
2718        while let Some(item) = cursor.item() {
2719            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2720                break;
2721            }
2722            if item.hunk_info().is_some() {
2723                return true;
2724            }
2725            cursor.next();
2726        }
2727        false
2728    }
2729
2730    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2731        let snapshot = self.read(cx);
2732        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2733        for range in ranges {
2734            let range = range.to_point(&snapshot);
2735            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2736            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2737            let start = start.saturating_sub(1);
2738            let end = snapshot.len().min(end + 1);
2739            cursor.seek(&start, Bias::Right);
2740            while let Some(item) = cursor.item() {
2741                if *cursor.start() >= end {
2742                    break;
2743                }
2744                if item.hunk_info().is_some() {
2745                    return true;
2746                }
2747                cursor.next();
2748            }
2749        }
2750        false
2751    }
2752
2753    pub fn expand_or_collapse_diff_hunks_inner(
2754        &mut self,
2755        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2756        expand: bool,
2757        cx: &mut Context<Self>,
2758    ) {
2759        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2760            return;
2761        }
2762        self.sync(cx);
2763        let mut snapshot = self.snapshot.borrow_mut();
2764        let mut excerpt_edits = Vec::new();
2765        let mut last_hunk_row = None;
2766        for (range, end_excerpt_id) in ranges {
2767            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2768                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2769                    continue;
2770                }
2771                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2772                    continue;
2773                }
2774                let start = Anchor::in_buffer(
2775                    diff_hunk.excerpt_id,
2776                    diff_hunk.buffer_id,
2777                    diff_hunk.buffer_range.start,
2778                );
2779                let end = Anchor::in_buffer(
2780                    diff_hunk.excerpt_id,
2781                    diff_hunk.buffer_id,
2782                    diff_hunk.buffer_range.end,
2783                );
2784                let start = snapshot.excerpt_offset_for_anchor(&start);
2785                let end = snapshot.excerpt_offset_for_anchor(&end);
2786                last_hunk_row = Some(diff_hunk.row_range.start);
2787                excerpt_edits.push(text::Edit {
2788                    old: start..end,
2789                    new: start..end,
2790                });
2791            }
2792        }
2793
2794        self.sync_diff_transforms(
2795            &mut snapshot,
2796            excerpt_edits,
2797            DiffChangeKind::ExpandOrCollapseHunks { expand },
2798        );
2799        cx.emit(Event::DiffHunksToggled);
2800        cx.emit(Event::Edited {
2801            singleton_buffer_edited: false,
2802            edited_buffer: None,
2803        });
2804    }
2805
2806    pub fn expand_or_collapse_diff_hunks(
2807        &mut self,
2808        ranges: Vec<Range<Anchor>>,
2809        expand: bool,
2810        cx: &mut Context<Self>,
2811    ) {
2812        let snapshot = self.snapshot.borrow().clone();
2813        let ranges = ranges.iter().map(move |range| {
2814            let end_excerpt_id = range.end.excerpt_id;
2815            let range = range.to_point(&snapshot);
2816            let mut peek_end = range.end;
2817            if range.end.row < snapshot.max_row().0 {
2818                peek_end = Point::new(range.end.row + 1, 0);
2819            };
2820            (range.start..peek_end, end_excerpt_id)
2821        });
2822        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2823    }
2824
2825    pub fn resize_excerpt(
2826        &mut self,
2827        id: ExcerptId,
2828        range: Range<text::Anchor>,
2829        cx: &mut Context<Self>,
2830    ) {
2831        self.sync(cx);
2832
2833        let mut snapshot = self.snapshot.borrow_mut();
2834        let locator = snapshot.excerpt_locator_for_id(id);
2835        let mut new_excerpts = SumTree::default();
2836        let mut cursor = snapshot
2837            .excerpts
2838            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2839        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2840
2841        let prefix = cursor.slice(&Some(locator), Bias::Left);
2842        new_excerpts.append(prefix, ());
2843
2844        let mut excerpt = cursor.item().unwrap().clone();
2845        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2846
2847        excerpt.range.context.start = range.start;
2848        excerpt.range.context.end = range.end;
2849        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2850
2851        excerpt.text_summary = excerpt
2852            .buffer
2853            .text_summary_for_range(excerpt.range.context.clone());
2854
2855        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2856        let old_start_offset = cursor.start().1;
2857        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2858        let edit = Edit {
2859            old: old_start_offset..old_start_offset + old_text_len,
2860            new: new_start_offset..new_start_offset + new_text_len,
2861        };
2862
2863        if let Some(last_edit) = edits.last_mut() {
2864            if last_edit.old.end == edit.old.start {
2865                last_edit.old.end = edit.old.end;
2866                last_edit.new.end = edit.new.end;
2867            } else {
2868                edits.push(edit);
2869            }
2870        } else {
2871            edits.push(edit);
2872        }
2873
2874        new_excerpts.push(excerpt, ());
2875
2876        cursor.next();
2877
2878        new_excerpts.append(cursor.suffix(), ());
2879
2880        drop(cursor);
2881        snapshot.excerpts = new_excerpts;
2882
2883        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2884        cx.emit(Event::Edited {
2885            singleton_buffer_edited: false,
2886            edited_buffer: None,
2887        });
2888        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2889        cx.notify();
2890    }
2891
2892    pub fn expand_excerpts(
2893        &mut self,
2894        ids: impl IntoIterator<Item = ExcerptId>,
2895        line_count: u32,
2896        direction: ExpandExcerptDirection,
2897        cx: &mut Context<Self>,
2898    ) {
2899        if line_count == 0 {
2900            return;
2901        }
2902        self.sync(cx);
2903        if !self.excerpts_by_path.is_empty() {
2904            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2905            return;
2906        }
2907        let mut snapshot = self.snapshot.borrow_mut();
2908
2909        let ids = ids.into_iter().collect::<Vec<_>>();
2910        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2911        let mut new_excerpts = SumTree::default();
2912        let mut cursor = snapshot
2913            .excerpts
2914            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2915        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2916
2917        for locator in &locators {
2918            let prefix = cursor.slice(&Some(locator), Bias::Left);
2919            new_excerpts.append(prefix, ());
2920
2921            let mut excerpt = cursor.item().unwrap().clone();
2922            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2923
2924            let up_line_count = if direction.should_expand_up() {
2925                line_count
2926            } else {
2927                0
2928            };
2929
2930            let start_row = excerpt
2931                .range
2932                .context
2933                .start
2934                .to_point(&excerpt.buffer)
2935                .row
2936                .saturating_sub(up_line_count);
2937            let start_point = Point::new(start_row, 0);
2938            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2939
2940            let down_line_count = if direction.should_expand_down() {
2941                line_count
2942            } else {
2943                0
2944            };
2945
2946            let mut end_point = excerpt.buffer.clip_point(
2947                excerpt.range.context.end.to_point(&excerpt.buffer)
2948                    + Point::new(down_line_count, 0),
2949                Bias::Left,
2950            );
2951            end_point.column = excerpt.buffer.line_len(end_point.row);
2952            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2953            excerpt.max_buffer_row = end_point.row;
2954
2955            excerpt.text_summary = excerpt
2956                .buffer
2957                .text_summary_for_range(excerpt.range.context.clone());
2958
2959            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2960            let old_start_offset = cursor.start().1;
2961            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2962            let edit = Edit {
2963                old: old_start_offset..old_start_offset + old_text_len,
2964                new: new_start_offset..new_start_offset + new_text_len,
2965            };
2966
2967            if let Some(last_edit) = edits.last_mut() {
2968                if last_edit.old.end == edit.old.start {
2969                    last_edit.old.end = edit.old.end;
2970                    last_edit.new.end = edit.new.end;
2971                } else {
2972                    edits.push(edit);
2973                }
2974            } else {
2975                edits.push(edit);
2976            }
2977
2978            new_excerpts.push(excerpt, ());
2979
2980            cursor.next();
2981        }
2982
2983        new_excerpts.append(cursor.suffix(), ());
2984
2985        drop(cursor);
2986        snapshot.excerpts = new_excerpts;
2987
2988        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2989        cx.emit(Event::Edited {
2990            singleton_buffer_edited: false,
2991            edited_buffer: None,
2992        });
2993        cx.emit(Event::ExcerptsExpanded { ids });
2994        cx.notify();
2995    }
2996
2997    fn sync(&self, cx: &App) {
2998        let changed = self.buffer_changed_since_sync.replace(false);
2999        if !changed {
3000            return;
3001        }
3002
3003        let mut snapshot = self.snapshot.borrow_mut();
3004        let mut excerpts_to_edit = Vec::new();
3005        let mut non_text_state_updated = false;
3006        let mut is_dirty = false;
3007        let mut has_deleted_file = false;
3008        let mut has_conflict = false;
3009        let mut edited = false;
3010        let mut buffers = self.buffers.borrow_mut();
3011        for buffer_state in buffers.values_mut() {
3012            let buffer = buffer_state.buffer.read(cx);
3013            let version = buffer.version();
3014            let non_text_state_update_count = buffer.non_text_state_update_count();
3015
3016            let buffer_edited = version.changed_since(&buffer_state.last_version);
3017            let buffer_non_text_state_updated =
3018                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3019            if buffer_edited || buffer_non_text_state_updated {
3020                buffer_state.last_version = version;
3021                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3022                excerpts_to_edit.extend(
3023                    buffer_state
3024                        .excerpts
3025                        .iter()
3026                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3027                );
3028            }
3029
3030            edited |= buffer_edited;
3031            non_text_state_updated |= buffer_non_text_state_updated;
3032            is_dirty |= buffer.is_dirty();
3033            has_deleted_file |= buffer
3034                .file()
3035                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3036            has_conflict |= buffer.has_conflict();
3037        }
3038        if edited {
3039            snapshot.edit_count += 1;
3040        }
3041        if non_text_state_updated {
3042            snapshot.non_text_state_update_count += 1;
3043        }
3044        snapshot.is_dirty = is_dirty;
3045        snapshot.has_deleted_file = has_deleted_file;
3046        snapshot.has_conflict = has_conflict;
3047
3048        for (id, diff) in self.diffs.iter() {
3049            if snapshot.diffs.get(id).is_none() {
3050                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3051            }
3052        }
3053
3054        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3055
3056        let mut edits = Vec::new();
3057        let mut new_excerpts = SumTree::default();
3058        let mut cursor = snapshot
3059            .excerpts
3060            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3061
3062        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3063            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3064            let old_excerpt = cursor.item().unwrap();
3065            let buffer = buffer.read(cx);
3066            let buffer_id = buffer.remote_id();
3067
3068            let mut new_excerpt;
3069            if buffer_edited {
3070                edits.extend(
3071                    buffer
3072                        .edits_since_in_range::<usize>(
3073                            old_excerpt.buffer.version(),
3074                            old_excerpt.range.context.clone(),
3075                        )
3076                        .map(|edit| {
3077                            let excerpt_old_start = cursor.start().1;
3078                            let excerpt_new_start =
3079                                ExcerptOffset::new(new_excerpts.summary().text.len);
3080                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3081                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3082                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3083                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3084                            Edit {
3085                                old: old_start..old_end,
3086                                new: new_start..new_end,
3087                            }
3088                        }),
3089                );
3090
3091                new_excerpt = Excerpt::new(
3092                    old_excerpt.id,
3093                    locator.clone(),
3094                    buffer_id,
3095                    buffer.snapshot(),
3096                    old_excerpt.range.clone(),
3097                    old_excerpt.has_trailing_newline,
3098                );
3099            } else {
3100                new_excerpt = old_excerpt.clone();
3101                new_excerpt.buffer = buffer.snapshot();
3102            }
3103
3104            new_excerpts.push(new_excerpt, ());
3105            cursor.next();
3106        }
3107        new_excerpts.append(cursor.suffix(), ());
3108
3109        drop(cursor);
3110        snapshot.excerpts = new_excerpts;
3111
3112        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3113    }
3114
3115    fn sync_diff_transforms(
3116        &self,
3117        snapshot: &mut MultiBufferSnapshot,
3118        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3119        change_kind: DiffChangeKind,
3120    ) {
3121        if excerpt_edits.is_empty() {
3122            return;
3123        }
3124
3125        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3126        let mut old_diff_transforms = snapshot
3127            .diff_transforms
3128            .cursor::<Dimensions<ExcerptOffset, usize>>(());
3129        let mut new_diff_transforms = SumTree::default();
3130        let mut old_expanded_hunks = HashSet::default();
3131        let mut output_edits = Vec::new();
3132        let mut output_delta = 0_isize;
3133        let mut at_transform_boundary = true;
3134        let mut end_of_current_insert = None;
3135
3136        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3137        while let Some(edit) = excerpt_edits.next() {
3138            excerpts.seek_forward(&edit.new.start, Bias::Right);
3139            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3140                excerpts.prev();
3141            }
3142
3143            // Keep any transforms that are before the edit.
3144            if at_transform_boundary {
3145                at_transform_boundary = false;
3146                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3147                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3148                if let Some(transform) = old_diff_transforms.item()
3149                    && old_diff_transforms.end().0 == edit.old.start
3150                    && old_diff_transforms.start().0 < edit.old.start
3151                {
3152                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3153                    old_diff_transforms.next();
3154                }
3155            }
3156
3157            // Compute the start of the edit in output coordinates.
3158            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3159            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3160            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3161
3162            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3163                &edit,
3164                &mut excerpts,
3165                &mut old_diff_transforms,
3166                &mut new_diff_transforms,
3167                &mut end_of_current_insert,
3168                &mut old_expanded_hunks,
3169                snapshot,
3170                change_kind,
3171            );
3172
3173            // Compute the end of the edit in output coordinates.
3174            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3175            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3176            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3177            let edit_new_end =
3178                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3179            let output_edit = Edit {
3180                old: edit_old_start..edit_old_end,
3181                new: edit_new_start..edit_new_end,
3182            };
3183
3184            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3185            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3186            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3187                output_edits.push(output_edit);
3188            }
3189
3190            // If this is the last edit that intersects the current diff transform,
3191            // then recreate the content up to the end of this transform, to prepare
3192            // for reusing additional slices of the old transforms.
3193            if excerpt_edits
3194                .peek()
3195                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3196            {
3197                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3198                    && match old_diff_transforms.item() {
3199                        Some(DiffTransform::BufferContent {
3200                            inserted_hunk_info: Some(hunk),
3201                            ..
3202                        }) => excerpts.item().is_some_and(|excerpt| {
3203                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3204                        }),
3205                        _ => true,
3206                    };
3207
3208                let mut excerpt_offset = edit.new.end;
3209                if !keep_next_old_transform {
3210                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3211                    old_diff_transforms.next();
3212                }
3213
3214                old_expanded_hunks.clear();
3215                self.push_buffer_content_transform(
3216                    snapshot,
3217                    &mut new_diff_transforms,
3218                    excerpt_offset,
3219                    end_of_current_insert,
3220                );
3221                at_transform_boundary = true;
3222            }
3223        }
3224
3225        // Keep any transforms that are after the last edit.
3226        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3227
3228        // Ensure there's always at least one buffer content transform.
3229        if new_diff_transforms.is_empty() {
3230            new_diff_transforms.push(
3231                DiffTransform::BufferContent {
3232                    summary: Default::default(),
3233                    inserted_hunk_info: None,
3234                },
3235                (),
3236            );
3237        }
3238
3239        self.subscriptions.publish(output_edits);
3240        drop(old_diff_transforms);
3241        drop(excerpts);
3242        snapshot.diff_transforms = new_diff_transforms;
3243        snapshot.edit_count += 1;
3244
3245        #[cfg(any(test, feature = "test-support"))]
3246        snapshot.check_invariants();
3247    }
3248
3249    fn recompute_diff_transforms_for_edit(
3250        &self,
3251        edit: &Edit<TypedOffset<Excerpt>>,
3252        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3253        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3254        new_diff_transforms: &mut SumTree<DiffTransform>,
3255        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3256        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3257        snapshot: &MultiBufferSnapshot,
3258        change_kind: DiffChangeKind,
3259    ) -> bool {
3260        log::trace!(
3261            "recomputing diff transform for edit {:?} => {:?}",
3262            edit.old.start.value..edit.old.end.value,
3263            edit.new.start.value..edit.new.end.value
3264        );
3265
3266        // Record which hunks were previously expanded.
3267        while let Some(item) = old_diff_transforms.item() {
3268            if let Some(hunk_info) = item.hunk_info() {
3269                log::trace!(
3270                    "previously expanded hunk at {}",
3271                    old_diff_transforms.start().0
3272                );
3273                old_expanded_hunks.insert(hunk_info);
3274            }
3275            if old_diff_transforms.end().0 > edit.old.end {
3276                break;
3277            }
3278            old_diff_transforms.next();
3279        }
3280
3281        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3282        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3283        if old_expanded_hunks.is_empty()
3284            && change_kind == DiffChangeKind::BufferEdited
3285            && !all_diff_hunks_expanded
3286        {
3287            return false;
3288        }
3289
3290        // Visit each excerpt that intersects the edit.
3291        let mut did_expand_hunks = false;
3292        while let Some(excerpt) = excerpts.item() {
3293            // Recompute the expanded hunks in the portion of the excerpt that
3294            // intersects the edit.
3295            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3296                let buffer = &excerpt.buffer;
3297                let excerpt_start = *excerpts.start();
3298                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3299                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3300                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3301                let edit_buffer_start =
3302                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3303                let edit_buffer_end =
3304                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3305                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3306                let edit_anchor_range =
3307                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3308
3309                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3310                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3311                        continue;
3312                    }
3313
3314                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3315                    if hunk_buffer_range.start < excerpt_buffer_start {
3316                        log::trace!("skipping hunk that starts before excerpt");
3317                        continue;
3318                    }
3319
3320                    let hunk_info = DiffTransformHunkInfo {
3321                        excerpt_id: excerpt.id,
3322                        hunk_start_anchor: hunk.buffer_range.start,
3323                        hunk_secondary_status: hunk.secondary_status,
3324                    };
3325
3326                    let hunk_excerpt_start = excerpt_start
3327                        + ExcerptOffset::new(
3328                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3329                        );
3330                    let hunk_excerpt_end = excerpt_end.min(
3331                        excerpt_start
3332                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3333                    );
3334
3335                    self.push_buffer_content_transform(
3336                        snapshot,
3337                        new_diff_transforms,
3338                        hunk_excerpt_start,
3339                        *end_of_current_insert,
3340                    );
3341
3342                    // For every existing hunk, determine if it was previously expanded
3343                    // and if it should currently be expanded.
3344                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3345                    let should_expand_hunk = match &change_kind {
3346                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3347                            was_previously_expanded || all_diff_hunks_expanded
3348                        }
3349                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3350                            let intersects = hunk_buffer_range.is_empty()
3351                                || hunk_buffer_range.end > edit_buffer_start;
3352                            if *expand {
3353                                intersects || was_previously_expanded || all_diff_hunks_expanded
3354                            } else {
3355                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3356                            }
3357                        }
3358                        _ => was_previously_expanded || all_diff_hunks_expanded,
3359                    };
3360
3361                    if should_expand_hunk {
3362                        did_expand_hunks = true;
3363                        log::trace!(
3364                            "expanding hunk {:?}, excerpt:{:?}",
3365                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3366                            excerpt.id
3367                        );
3368
3369                        if !hunk.diff_base_byte_range.is_empty()
3370                            && hunk_buffer_range.start >= edit_buffer_start
3371                            && hunk_buffer_range.start <= excerpt_buffer_end
3372                        {
3373                            let base_text = diff.base_text();
3374                            let mut text_cursor =
3375                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3376                            let mut base_text_summary =
3377                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3378
3379                            let mut has_trailing_newline = false;
3380                            if base_text_summary.last_line_chars > 0 {
3381                                base_text_summary += TextSummary::newline();
3382                                has_trailing_newline = true;
3383                            }
3384
3385                            new_diff_transforms.push(
3386                                DiffTransform::DeletedHunk {
3387                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3388                                    summary: base_text_summary,
3389                                    buffer_id: excerpt.buffer_id,
3390                                    hunk_info,
3391                                    has_trailing_newline,
3392                                },
3393                                (),
3394                            );
3395                        }
3396
3397                        if !hunk_buffer_range.is_empty() {
3398                            *end_of_current_insert =
3399                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3400                        }
3401                    }
3402                }
3403            }
3404
3405            if excerpts.end() <= edit.new.end {
3406                excerpts.next();
3407            } else {
3408                break;
3409            }
3410        }
3411
3412        did_expand_hunks || !old_expanded_hunks.is_empty()
3413    }
3414
3415    fn append_diff_transforms(
3416        &self,
3417        new_transforms: &mut SumTree<DiffTransform>,
3418        subtree: SumTree<DiffTransform>,
3419    ) {
3420        if let Some(DiffTransform::BufferContent {
3421            inserted_hunk_info,
3422            summary,
3423        }) = subtree.first()
3424            && self.extend_last_buffer_content_transform(
3425                new_transforms,
3426                *inserted_hunk_info,
3427                *summary,
3428            )
3429        {
3430            let mut cursor = subtree.cursor::<()>(());
3431            cursor.next();
3432            cursor.next();
3433            new_transforms.append(cursor.suffix(), ());
3434            return;
3435        }
3436        new_transforms.append(subtree, ());
3437    }
3438
3439    fn push_diff_transform(
3440        &self,
3441        new_transforms: &mut SumTree<DiffTransform>,
3442        transform: DiffTransform,
3443    ) {
3444        if let DiffTransform::BufferContent {
3445            inserted_hunk_info: inserted_hunk_anchor,
3446            summary,
3447        } = transform
3448            && self.extend_last_buffer_content_transform(
3449                new_transforms,
3450                inserted_hunk_anchor,
3451                summary,
3452            )
3453        {
3454            return;
3455        }
3456        new_transforms.push(transform, ());
3457    }
3458
3459    fn push_buffer_content_transform(
3460        &self,
3461        old_snapshot: &MultiBufferSnapshot,
3462        new_transforms: &mut SumTree<DiffTransform>,
3463        end_offset: ExcerptOffset,
3464        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3465    ) {
3466        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3467            (end_offset.min(insertion_end_offset), Some(hunk_info))
3468        });
3469        let unchanged_region = [(end_offset, None)];
3470
3471        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3472        {
3473            let start_offset = new_transforms.summary().excerpt_len();
3474            if end_offset <= start_offset {
3475                continue;
3476            }
3477            let summary_to_add = old_snapshot
3478                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3479
3480            if !self.extend_last_buffer_content_transform(
3481                new_transforms,
3482                inserted_hunk_info,
3483                summary_to_add,
3484            ) {
3485                new_transforms.push(
3486                    DiffTransform::BufferContent {
3487                        summary: summary_to_add,
3488                        inserted_hunk_info,
3489                    },
3490                    (),
3491                )
3492            }
3493        }
3494    }
3495
3496    fn extend_last_buffer_content_transform(
3497        &self,
3498        new_transforms: &mut SumTree<DiffTransform>,
3499        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3500        summary_to_add: TextSummary,
3501    ) -> bool {
3502        let mut did_extend = false;
3503        new_transforms.update_last(
3504            |last_transform| {
3505                if let DiffTransform::BufferContent {
3506                    summary,
3507                    inserted_hunk_info: inserted_hunk_anchor,
3508                } = last_transform
3509                    && *inserted_hunk_anchor == new_inserted_hunk_info
3510                {
3511                    *summary += summary_to_add;
3512                    did_extend = true;
3513                }
3514            },
3515            (),
3516        );
3517        did_extend
3518    }
3519}
3520
3521fn build_excerpt_ranges(
3522    ranges: impl IntoIterator<Item = Range<Point>>,
3523    context_line_count: u32,
3524    buffer_snapshot: &BufferSnapshot,
3525) -> Vec<ExcerptRange<Point>> {
3526    ranges
3527        .into_iter()
3528        .map(|range| {
3529            let start_row = range.start.row.saturating_sub(context_line_count);
3530            let start = Point::new(start_row, 0);
3531            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3532            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3533            ExcerptRange {
3534                context: start..end,
3535                primary: range,
3536            }
3537        })
3538        .collect()
3539}
3540
3541#[cfg(any(test, feature = "test-support"))]
3542impl MultiBuffer {
3543    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3544        let buffer = cx.new(|cx| Buffer::local(text, cx));
3545        cx.new(|cx| Self::singleton(buffer, cx))
3546    }
3547
3548    pub fn build_multi<const COUNT: usize>(
3549        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3550        cx: &mut gpui::App,
3551    ) -> Entity<Self> {
3552        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3553        for (text, ranges) in excerpts {
3554            let buffer = cx.new(|cx| Buffer::local(text, cx));
3555            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3556            multi.update(cx, |multi, cx| {
3557                multi.push_excerpts(buffer, excerpt_ranges, cx)
3558            });
3559        }
3560
3561        multi
3562    }
3563
3564    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3565        cx.new(|cx| Self::singleton(buffer, cx))
3566    }
3567
3568    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3569        cx.new(|cx| {
3570            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3571            let mutation_count = rng.random_range(1..=5);
3572            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3573            multibuffer
3574        })
3575    }
3576
3577    pub fn randomly_edit(
3578        &mut self,
3579        rng: &mut impl rand::Rng,
3580        edit_count: usize,
3581        cx: &mut Context<Self>,
3582    ) {
3583        use util::RandomCharIter;
3584
3585        let snapshot = self.read(cx);
3586        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3587        let mut last_end = None;
3588        for _ in 0..edit_count {
3589            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3590                break;
3591            }
3592
3593            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3594            let end =
3595                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3596            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3597            last_end = Some(end);
3598
3599            let mut range = start..end;
3600            if rng.random_bool(0.2) {
3601                mem::swap(&mut range.start, &mut range.end);
3602            }
3603
3604            let new_text_len = rng.random_range(0..10);
3605            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3606
3607            edits.push((range, new_text.into()));
3608        }
3609        log::info!("mutating multi-buffer with {:?}", edits);
3610        drop(snapshot);
3611
3612        self.edit(edits, None, cx);
3613    }
3614
3615    pub fn randomly_edit_excerpts(
3616        &mut self,
3617        rng: &mut impl rand::Rng,
3618        mutation_count: usize,
3619        cx: &mut Context<Self>,
3620    ) {
3621        use rand::prelude::*;
3622        use std::env;
3623        use util::RandomCharIter;
3624
3625        let max_excerpts = env::var("MAX_EXCERPTS")
3626            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3627            .unwrap_or(5);
3628
3629        let mut buffers = Vec::new();
3630        for _ in 0..mutation_count {
3631            if rng.random_bool(0.05) {
3632                log::info!("Clearing multi-buffer");
3633                self.clear(cx);
3634                continue;
3635            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3636                let ids = self.excerpt_ids();
3637                let mut excerpts = HashSet::default();
3638                for _ in 0..rng.random_range(0..ids.len()) {
3639                    excerpts.extend(ids.choose(rng).copied());
3640                }
3641
3642                let line_count = rng.random_range(0..5);
3643
3644                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3645
3646                self.expand_excerpts(
3647                    excerpts.iter().cloned(),
3648                    line_count,
3649                    ExpandExcerptDirection::UpAndDown,
3650                    cx,
3651                );
3652                continue;
3653            }
3654
3655            let excerpt_ids = self.excerpt_ids();
3656            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3657                let buffer_handle = if rng.random() || self.buffers.borrow().is_empty() {
3658                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3659                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3660                    let buffer = buffers.last().unwrap().read(cx);
3661                    log::info!(
3662                        "Creating new buffer {} with text: {:?}",
3663                        buffer.remote_id(),
3664                        buffer.text()
3665                    );
3666                    buffers.last().unwrap().clone()
3667                } else {
3668                    self.buffers
3669                        .borrow()
3670                        .values()
3671                        .choose(rng)
3672                        .unwrap()
3673                        .buffer
3674                        .clone()
3675                };
3676
3677                let buffer = buffer_handle.read(cx);
3678                let buffer_text = buffer.text();
3679                let ranges = (0..rng.random_range(0..5))
3680                    .map(|_| {
3681                        let end_ix =
3682                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3683                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3684                        ExcerptRange::new(start_ix..end_ix)
3685                    })
3686                    .collect::<Vec<_>>();
3687                log::info!(
3688                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3689                    buffer_handle.read(cx).remote_id(),
3690                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3691                    ranges
3692                        .iter()
3693                        .map(|r| &buffer_text[r.context.clone()])
3694                        .collect::<Vec<_>>()
3695                );
3696
3697                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3698                log::info!("Inserted with ids: {:?}", excerpt_id);
3699            } else {
3700                let remove_count = rng.random_range(1..=excerpt_ids.len());
3701                let mut excerpts_to_remove = excerpt_ids
3702                    .choose_multiple(rng, remove_count)
3703                    .cloned()
3704                    .collect::<Vec<_>>();
3705                let snapshot = self.snapshot.borrow();
3706                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3707                drop(snapshot);
3708                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3709                self.remove_excerpts(excerpts_to_remove, cx);
3710            }
3711        }
3712    }
3713
3714    pub fn randomly_mutate(
3715        &mut self,
3716        rng: &mut impl rand::Rng,
3717        mutation_count: usize,
3718        cx: &mut Context<Self>,
3719    ) {
3720        use rand::prelude::*;
3721
3722        if rng.random_bool(0.7) || self.singleton {
3723            let buffer = self
3724                .buffers
3725                .borrow()
3726                .values()
3727                .choose(rng)
3728                .map(|state| state.buffer.clone());
3729
3730            if let Some(buffer) = buffer {
3731                buffer.update(cx, |buffer, cx| {
3732                    if rng.random() {
3733                        buffer.randomly_edit(rng, mutation_count, cx);
3734                    } else {
3735                        buffer.randomly_undo_redo(rng, cx);
3736                    }
3737                });
3738            } else {
3739                self.randomly_edit(rng, mutation_count, cx);
3740            }
3741        } else {
3742            self.randomly_edit_excerpts(rng, mutation_count, cx);
3743        }
3744
3745        self.check_invariants(cx);
3746    }
3747
3748    fn check_invariants(&self, cx: &App) {
3749        self.read(cx).check_invariants();
3750    }
3751}
3752
3753impl EventEmitter<Event> for MultiBuffer {}
3754
3755impl MultiBufferSnapshot {
3756    pub fn text(&self) -> String {
3757        self.chunks(0..self.len(), false)
3758            .map(|chunk| chunk.text)
3759            .collect()
3760    }
3761
3762    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3763        self.reversed_chunks_in_range(0..position.to_offset(self))
3764            .flat_map(|c| c.chars().rev())
3765    }
3766
3767    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3768        let mut cursor = self.cursor::<usize>();
3769        cursor.seek(&range.end);
3770        let current_chunks = cursor.region().as_ref().map(|region| {
3771            let start_overshoot = range.start.saturating_sub(region.range.start);
3772            let end_overshoot = range.end - region.range.start;
3773            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3774            let start = region.buffer_range.start + start_overshoot;
3775            region.buffer.reversed_chunks_in_range(start..end)
3776        });
3777        ReversedMultiBufferChunks {
3778            cursor,
3779            current_chunks,
3780            start: range.start,
3781            offset: range.end,
3782        }
3783    }
3784
3785    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3786        let offset = position.to_offset(self);
3787        self.text_for_range(offset..self.len())
3788            .flat_map(|chunk| chunk.chars())
3789    }
3790
3791    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3792        self.chunks(range, false).map(|chunk| chunk.text)
3793    }
3794
3795    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3796        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3797            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3798    }
3799
3800    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3801    where
3802        T: ToOffset,
3803    {
3804        let position = position.to_offset(self);
3805        position == self.clip_offset(position, Bias::Left)
3806            && self
3807                .bytes_in_range(position..self.len())
3808                .flatten()
3809                .copied()
3810                .take(needle.len())
3811                .eq(needle.bytes())
3812    }
3813
3814    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3815        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3816    }
3817
3818    pub fn diff_hunks_in_range<T: ToPoint>(
3819        &self,
3820        range: Range<T>,
3821    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3822        let query_range = range.start.to_point(self)..range.end.to_point(self);
3823        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3824            let diff = self.diffs.get(&buffer.remote_id())?;
3825            let buffer_start = buffer.anchor_before(buffer_range.start);
3826            let buffer_end = buffer.anchor_after(buffer_range.end);
3827            Some(
3828                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3829                    .filter_map(|hunk| {
3830                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3831                            return None;
3832                        }
3833                        Some((hunk.range.clone(), hunk))
3834                    }),
3835            )
3836        })
3837        .filter_map(move |(range, hunk, excerpt)| {
3838            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3839            {
3840                return None;
3841            }
3842            let end_row = if range.end.column == 0 {
3843                range.end.row
3844            } else {
3845                range.end.row + 1
3846            };
3847            Some(MultiBufferDiffHunk {
3848                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3849                buffer_id: excerpt.buffer_id,
3850                excerpt_id: excerpt.id,
3851                buffer_range: hunk.buffer_range.clone(),
3852                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3853                secondary_status: hunk.secondary_status,
3854            })
3855        })
3856    }
3857
3858    pub fn excerpt_ids_for_range<T: ToOffset>(
3859        &self,
3860        range: Range<T>,
3861    ) -> impl Iterator<Item = ExcerptId> + '_ {
3862        let range = range.start.to_offset(self)..range.end.to_offset(self);
3863        let mut cursor = self.cursor::<usize>();
3864        cursor.seek(&range.start);
3865        std::iter::from_fn(move || {
3866            let region = cursor.region()?;
3867            if region.range.start >= range.end {
3868                return None;
3869            }
3870            cursor.next_excerpt();
3871            Some(region.excerpt.id)
3872        })
3873    }
3874
3875    pub fn buffer_ids_for_range<T: ToOffset>(
3876        &self,
3877        range: Range<T>,
3878    ) -> impl Iterator<Item = BufferId> + '_ {
3879        let range = range.start.to_offset(self)..range.end.to_offset(self);
3880        let mut cursor = self.cursor::<usize>();
3881        cursor.seek(&range.start);
3882        std::iter::from_fn(move || {
3883            let region = cursor.region()?;
3884            if region.range.start > range.end
3885                || region.range.start == range.end && region.range.start > range.start
3886            {
3887                return None;
3888            }
3889            cursor.next_excerpt();
3890            Some(region.excerpt.buffer_id)
3891        })
3892    }
3893
3894    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3895        &self,
3896        ranges: impl Iterator<Item = Range<T>>,
3897    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3898        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3899    }
3900
3901    pub fn range_to_buffer_ranges<T: ToOffset>(
3902        &self,
3903        range: Range<T>,
3904    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3905        let start = range.start.to_offset(self);
3906        let end = range.end.to_offset(self);
3907
3908        let mut cursor = self.cursor::<usize>();
3909        cursor.seek(&start);
3910
3911        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3912        while let Some(region) = cursor.region() {
3913            if region.range.start > end {
3914                break;
3915            }
3916            if region.is_main_buffer {
3917                let start_overshoot = start.saturating_sub(region.range.start);
3918                let end_overshoot = end.saturating_sub(region.range.start);
3919                let start = region
3920                    .buffer_range
3921                    .end
3922                    .min(region.buffer_range.start + start_overshoot);
3923                let end = region
3924                    .buffer_range
3925                    .end
3926                    .min(region.buffer_range.start + end_overshoot);
3927                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3928                    *excerpt_id == region.excerpt.id && prev_range.end == start
3929                }) {
3930                    prev.1.end = end;
3931                } else {
3932                    result.push((region.buffer, start..end, region.excerpt.id));
3933                }
3934            }
3935            cursor.next();
3936        }
3937        result
3938    }
3939
3940    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3941        &self,
3942        range: Range<T>,
3943    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3944        let start = range.start.to_offset(self);
3945        let end = range.end.to_offset(self);
3946
3947        let mut cursor = self.cursor::<usize>();
3948        cursor.seek(&start);
3949
3950        std::iter::from_fn(move || {
3951            let region = cursor.region()?;
3952            if region.range.start > end {
3953                return None;
3954            }
3955            let start_overshoot = start.saturating_sub(region.range.start);
3956            let end_overshoot = end.saturating_sub(region.range.start);
3957            let start = region
3958                .buffer_range
3959                .end
3960                .min(region.buffer_range.start + start_overshoot);
3961            let end = region
3962                .buffer_range
3963                .end
3964                .min(region.buffer_range.start + end_overshoot);
3965
3966            let region_excerpt_id = region.excerpt.id;
3967            let deleted_hunk_anchor = if region.is_main_buffer {
3968                None
3969            } else {
3970                Some(self.anchor_before(region.range.start))
3971            };
3972            let result = (
3973                region.buffer,
3974                start..end,
3975                region_excerpt_id,
3976                deleted_hunk_anchor,
3977            );
3978            cursor.next();
3979            Some(result)
3980        })
3981    }
3982
3983    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3984    /// coordinates.
3985    ///
3986    /// The given callback will be called for every excerpt intersecting the given range. It will
3987    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3988    /// The callback should return an iterator of metadata items from that buffer, each paired
3989    /// with a buffer range.
3990    ///
3991    /// The returned iterator yields each of these metadata items, paired with its range in
3992    /// multi-buffer coordinates.
3993    fn lift_buffer_metadata<'a, D, M, I>(
3994        &'a self,
3995        query_range: Range<D>,
3996        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
3997    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
3998    where
3999        I: Iterator<Item = (Range<D>, M)> + 'a,
4000        D: TextDimension + Ord + Sub<D, Output = D>,
4001    {
4002        let max_position = D::from_text_summary(&self.text_summary());
4003        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4004        let mut cursor = self.cursor::<D>();
4005
4006        // Find the excerpt and buffer offset where the given range ends.
4007        cursor.seek(&query_range.end);
4008        let mut range_end = None;
4009        while let Some(region) = cursor.region() {
4010            if region.is_main_buffer {
4011                let mut buffer_end = region.buffer_range.start;
4012                let overshoot = if query_range.end > region.range.start {
4013                    query_range.end - region.range.start
4014                } else {
4015                    D::default()
4016                };
4017                buffer_end.add_assign(&overshoot);
4018                range_end = Some((region.excerpt.id, buffer_end));
4019                break;
4020            }
4021            cursor.next();
4022        }
4023
4024        cursor.seek(&query_range.start);
4025
4026        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4027            && region.range.start > D::zero(())
4028        {
4029            cursor.prev()
4030        }
4031
4032        iter::from_fn(move || {
4033            loop {
4034                let excerpt = cursor.excerpt()?;
4035
4036                // If we have already retrieved metadata for this excerpt, continue to use it.
4037                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4038                    .as_mut()
4039                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4040                {
4041                    Some(metadata)
4042                }
4043                // Otherwise, compute the intersection of the input range with the excerpt's range,
4044                // and retrieve the metadata for the resulting range.
4045                else {
4046                    let region = cursor.region()?;
4047                    let mut buffer_start;
4048                    if region.is_main_buffer {
4049                        buffer_start = region.buffer_range.start;
4050                        if query_range.start > region.range.start {
4051                            let overshoot = query_range.start - region.range.start;
4052                            buffer_start.add_assign(&overshoot);
4053                        }
4054                        buffer_start = buffer_start.min(region.buffer_range.end);
4055                    } else {
4056                        buffer_start = cursor.main_buffer_position()?;
4057                    };
4058                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4059                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4060                        && excerpt.id == end_excerpt_id
4061                    {
4062                        buffer_end = buffer_end.min(end_buffer_offset);
4063                    }
4064
4065                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4066                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4067                    })
4068                };
4069
4070                // Visit each metadata item.
4071                if let Some((metadata_buffer_range, metadata)) =
4072                    metadata_iter.and_then(Iterator::next)
4073                {
4074                    // Find the multibuffer regions that contain the start and end of
4075                    // the metadata item's range.
4076                    if metadata_buffer_range.start > D::default() {
4077                        while let Some(region) = cursor.region() {
4078                            if region.is_main_buffer
4079                                && (region.buffer_range.end >= metadata_buffer_range.start
4080                                    || cursor.is_at_end_of_excerpt())
4081                            {
4082                                break;
4083                            }
4084                            cursor.next();
4085                        }
4086                    }
4087                    let start_region = cursor.region()?;
4088                    while let Some(region) = cursor.region() {
4089                        if region.is_main_buffer
4090                            && (region.buffer_range.end > metadata_buffer_range.end
4091                                || cursor.is_at_end_of_excerpt())
4092                        {
4093                            break;
4094                        }
4095                        cursor.next();
4096                    }
4097                    let end_region = cursor.region();
4098
4099                    // Convert the metadata item's range into multibuffer coordinates.
4100                    let mut start_position = start_region.range.start;
4101                    let region_buffer_start = start_region.buffer_range.start;
4102                    if start_region.is_main_buffer
4103                        && metadata_buffer_range.start > region_buffer_start
4104                    {
4105                        start_position
4106                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4107                        start_position = start_position.min(start_region.range.end);
4108                    }
4109
4110                    let mut end_position = max_position;
4111                    if let Some(end_region) = &end_region {
4112                        end_position = end_region.range.start;
4113                        debug_assert!(end_region.is_main_buffer);
4114                        let region_buffer_start = end_region.buffer_range.start;
4115                        if metadata_buffer_range.end > region_buffer_start {
4116                            end_position
4117                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4118                        }
4119                        end_position = end_position.min(end_region.range.end);
4120                    }
4121
4122                    if start_position <= query_range.end && end_position >= query_range.start {
4123                        return Some((start_position..end_position, metadata, excerpt));
4124                    }
4125                }
4126                // When there are no more metadata items for this excerpt, move to the next excerpt.
4127                else {
4128                    current_excerpt_metadata.take();
4129                    if let Some((end_excerpt_id, _)) = range_end
4130                        && excerpt.id == end_excerpt_id
4131                    {
4132                        return None;
4133                    }
4134                    cursor.next_excerpt();
4135                }
4136            }
4137        })
4138    }
4139
4140    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4141        let offset = position.to_offset(self);
4142
4143        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4144        cursor.seek(&DimensionPair {
4145            key: offset,
4146            value: None,
4147        });
4148        cursor.seek_to_start_of_current_excerpt();
4149        let excerpt = cursor.excerpt()?;
4150
4151        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4152        let current_position = self
4153            .anchor_before(offset)
4154            .text_anchor
4155            .to_offset(&excerpt.buffer);
4156        let excerpt_end = excerpt
4157            .buffer
4158            .anchor_before(excerpt_end.min(current_position));
4159
4160        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4161            for hunk in diff.hunks_intersecting_range_rev(
4162                excerpt.range.context.start..excerpt_end,
4163                &excerpt.buffer,
4164            ) {
4165                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4166                if hunk_end >= current_position {
4167                    continue;
4168                }
4169                let start =
4170                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4171                        .to_point(self);
4172                return Some(MultiBufferRow(start.row));
4173            }
4174        }
4175
4176        loop {
4177            cursor.prev_excerpt();
4178            let excerpt = cursor.excerpt()?;
4179
4180            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4181                continue;
4182            };
4183            let mut hunks =
4184                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4185            let Some(hunk) = hunks.next() else {
4186                continue;
4187            };
4188            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4189                .to_point(self);
4190            return Some(MultiBufferRow(start.row));
4191        }
4192    }
4193
4194    pub fn has_diff_hunks(&self) -> bool {
4195        self.diffs.values().any(|diff| !diff.is_empty())
4196    }
4197
4198    pub fn is_inside_word<T: ToOffset>(
4199        &self,
4200        position: T,
4201        scope_context: Option<CharScopeContext>,
4202    ) -> bool {
4203        let position = position.to_offset(self);
4204        let classifier = self
4205            .char_classifier_at(position)
4206            .scope_context(scope_context);
4207        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4208        let prev_char_kind = self
4209            .reversed_chars_at(position)
4210            .next()
4211            .map(|c| classifier.kind(c));
4212        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4213    }
4214
4215    pub fn surrounding_word<T: ToOffset>(
4216        &self,
4217        start: T,
4218        scope_context: Option<CharScopeContext>,
4219    ) -> (Range<usize>, Option<CharKind>) {
4220        let mut start = start.to_offset(self);
4221        let mut end = start;
4222        let mut next_chars = self.chars_at(start).peekable();
4223        let mut prev_chars = self.reversed_chars_at(start).peekable();
4224
4225        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4226
4227        let word_kind = cmp::max(
4228            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4229            next_chars.peek().copied().map(|c| classifier.kind(c)),
4230        );
4231
4232        for ch in prev_chars {
4233            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4234                start -= ch.len_utf8();
4235            } else {
4236                break;
4237            }
4238        }
4239
4240        for ch in next_chars {
4241            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4242                end += ch.len_utf8();
4243            } else {
4244                break;
4245            }
4246        }
4247
4248        (start..end, word_kind)
4249    }
4250
4251    pub fn char_kind_before<T: ToOffset>(
4252        &self,
4253        start: T,
4254        scope_context: Option<CharScopeContext>,
4255    ) -> Option<CharKind> {
4256        let start = start.to_offset(self);
4257        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4258        self.reversed_chars_at(start)
4259            .next()
4260            .map(|ch| classifier.kind(ch))
4261    }
4262
4263    pub fn is_singleton(&self) -> bool {
4264        self.singleton
4265    }
4266
4267    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4268        if self.singleton {
4269            self.excerpts
4270                .iter()
4271                .next()
4272                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4273        } else {
4274            None
4275        }
4276    }
4277
4278    pub fn len(&self) -> usize {
4279        self.diff_transforms.summary().output.len
4280    }
4281
4282    pub fn is_empty(&self) -> bool {
4283        self.excerpts.summary().text.len == 0
4284    }
4285
4286    pub fn widest_line_number(&self) -> u32 {
4287        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4288        self.excerpts.summary().widest_line_number + 1
4289    }
4290
4291    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4292        let range = range.start.to_offset(self)..range.end.to_offset(self);
4293        let mut excerpts = self.cursor::<usize>();
4294        excerpts.seek(&range.start);
4295
4296        let mut chunk;
4297        let mut has_trailing_newline;
4298        let excerpt_bytes;
4299        if let Some(region) = excerpts.region() {
4300            let mut bytes = region.buffer.bytes_in_range(
4301                region.buffer_range.start + range.start - region.range.start
4302                    ..(region.buffer_range.start + range.end - region.range.start)
4303                        .min(region.buffer_range.end),
4304            );
4305            chunk = bytes.next().unwrap_or(&[][..]);
4306            excerpt_bytes = Some(bytes);
4307            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4308            if chunk.is_empty() && has_trailing_newline {
4309                chunk = b"\n";
4310                has_trailing_newline = false;
4311            }
4312        } else {
4313            chunk = &[][..];
4314            excerpt_bytes = None;
4315            has_trailing_newline = false;
4316        };
4317
4318        MultiBufferBytes {
4319            range,
4320            cursor: excerpts,
4321            excerpt_bytes,
4322            has_trailing_newline,
4323            chunk,
4324        }
4325    }
4326
4327    pub fn reversed_bytes_in_range<T: ToOffset>(
4328        &self,
4329        range: Range<T>,
4330    ) -> ReversedMultiBufferBytes<'_> {
4331        let range = range.start.to_offset(self)..range.end.to_offset(self);
4332        let mut chunks = self.reversed_chunks_in_range(range.clone());
4333        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4334        ReversedMultiBufferBytes {
4335            range,
4336            chunks,
4337            chunk,
4338        }
4339    }
4340
4341    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4342        let mut cursor = self.cursor::<Point>();
4343        cursor.seek(&Point::new(start_row.0, 0));
4344        let mut result = MultiBufferRows {
4345            point: Point::new(0, 0),
4346            is_empty: self.excerpts.is_empty(),
4347            is_singleton: self.is_singleton(),
4348            cursor,
4349        };
4350        result.seek(start_row);
4351        result
4352    }
4353
4354    pub fn chunks<T: ToOffset>(
4355        &self,
4356        range: Range<T>,
4357        language_aware: bool,
4358    ) -> MultiBufferChunks<'_> {
4359        let mut chunks = MultiBufferChunks {
4360            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4361            range: 0..0,
4362            excerpts: self.excerpts.cursor(()),
4363            diff_transforms: self.diff_transforms.cursor(()),
4364            diffs: &self.diffs,
4365            diff_base_chunks: None,
4366            excerpt_chunks: None,
4367            buffer_chunk: None,
4368            language_aware,
4369        };
4370        let range = range.start.to_offset(self)..range.end.to_offset(self);
4371        chunks.seek(range);
4372        chunks
4373    }
4374
4375    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4376        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4377    }
4378
4379    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4380        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4381    }
4382
4383    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4384        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4385    }
4386
4387    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4388        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4389            buffer.clip_point_utf16(Unclipped(point), bias)
4390        })
4391    }
4392
4393    pub fn offset_to_point(&self, offset: usize) -> Point {
4394        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4395    }
4396
4397    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4398        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4399    }
4400
4401    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4402        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4403    }
4404
4405    pub fn point_to_offset(&self, point: Point) -> usize {
4406        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4407    }
4408
4409    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4410        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4411    }
4412
4413    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4414        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4415    }
4416
4417    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4418        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4419    }
4420
4421    fn clip_dimension<D>(
4422        &self,
4423        position: D,
4424        bias: Bias,
4425        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4426    ) -> D
4427    where
4428        D: TextDimension + Ord + Sub<D, Output = D>,
4429    {
4430        let mut cursor = self.cursor();
4431        cursor.seek(&position);
4432        if let Some(region) = cursor.region() {
4433            if position >= region.range.end {
4434                return region.range.end;
4435            }
4436            let overshoot = position - region.range.start;
4437            let mut buffer_position = region.buffer_range.start;
4438            buffer_position.add_assign(&overshoot);
4439            let clipped_buffer_position =
4440                clip_buffer_position(region.buffer, buffer_position, bias);
4441            let mut position = region.range.start;
4442            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4443            position
4444        } else {
4445            D::from_text_summary(&self.text_summary())
4446        }
4447    }
4448
4449    fn convert_dimension<D1, D2>(
4450        &self,
4451        key: D1,
4452        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4453    ) -> D2
4454    where
4455        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4456        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4457    {
4458        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4459        cursor.seek(&DimensionPair { key, value: None });
4460        if let Some(region) = cursor.region() {
4461            if key >= region.range.end.key {
4462                return region.range.end.value.unwrap();
4463            }
4464            let start_key = region.range.start.key;
4465            let start_value = region.range.start.value.unwrap();
4466            let buffer_start_key = region.buffer_range.start.key;
4467            let buffer_start_value = region.buffer_range.start.value.unwrap();
4468            let mut buffer_key = buffer_start_key;
4469            buffer_key.add_assign(&(key - start_key));
4470            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4471            let mut result = start_value;
4472            result.add_assign(&(buffer_value - buffer_start_value));
4473            result
4474        } else {
4475            D2::from_text_summary(&self.text_summary())
4476        }
4477    }
4478
4479    pub fn point_to_buffer_offset<T: ToOffset>(
4480        &self,
4481        point: T,
4482    ) -> Option<(&BufferSnapshot, usize)> {
4483        let offset = point.to_offset(self);
4484        let mut cursor = self.cursor::<usize>();
4485        cursor.seek(&offset);
4486        let region = cursor.region()?;
4487        let overshoot = offset - region.range.start;
4488        let buffer_offset = region.buffer_range.start + overshoot;
4489        if buffer_offset == region.buffer.len() + 1
4490            && region.has_trailing_newline
4491            && !region.is_main_buffer
4492        {
4493            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4494        } else if buffer_offset > region.buffer.len() {
4495            return None;
4496        }
4497        Some((region.buffer, buffer_offset))
4498    }
4499
4500    pub fn point_to_buffer_point(
4501        &self,
4502        point: Point,
4503    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4504        let mut cursor = self.cursor::<Point>();
4505        cursor.seek(&point);
4506        let region = cursor.region()?;
4507        let overshoot = point - region.range.start;
4508        let buffer_point = region.buffer_range.start + overshoot;
4509        let excerpt = cursor.excerpt()?;
4510        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4511            && region.has_trailing_newline
4512            && !region.is_main_buffer
4513        {
4514            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4515        } else if buffer_point > region.buffer.max_point() {
4516            return None;
4517        }
4518        Some((region.buffer, buffer_point, excerpt.id))
4519    }
4520
4521    pub fn suggested_indents(
4522        &self,
4523        rows: impl IntoIterator<Item = u32>,
4524        cx: &App,
4525    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4526        let mut result = BTreeMap::new();
4527
4528        let mut rows_for_excerpt = Vec::new();
4529        let mut cursor = self.cursor::<Point>();
4530        let mut rows = rows.into_iter().peekable();
4531        let mut prev_row = u32::MAX;
4532        let mut prev_language_indent_size = IndentSize::default();
4533
4534        while let Some(row) = rows.next() {
4535            cursor.seek(&Point::new(row, 0));
4536            let Some(region) = cursor.region() else {
4537                continue;
4538            };
4539
4540            // Retrieve the language and indent size once for each disjoint region being indented.
4541            let single_indent_size = if row.saturating_sub(1) == prev_row {
4542                prev_language_indent_size
4543            } else {
4544                region
4545                    .buffer
4546                    .language_indent_size_at(Point::new(row, 0), cx)
4547            };
4548            prev_language_indent_size = single_indent_size;
4549            prev_row = row;
4550
4551            let start_buffer_row = region.buffer_range.start.row;
4552            let start_multibuffer_row = region.range.start.row;
4553            let end_multibuffer_row = region.range.end.row;
4554
4555            rows_for_excerpt.push(row);
4556            while let Some(next_row) = rows.peek().copied() {
4557                if end_multibuffer_row > next_row {
4558                    rows_for_excerpt.push(next_row);
4559                    rows.next();
4560                } else {
4561                    break;
4562                }
4563            }
4564
4565            let buffer_rows = rows_for_excerpt
4566                .drain(..)
4567                .map(|row| start_buffer_row + row - start_multibuffer_row);
4568            let buffer_indents = region
4569                .buffer
4570                .suggested_indents(buffer_rows, single_indent_size);
4571            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4572                (
4573                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4574                    indent,
4575                )
4576            });
4577            result.extend(multibuffer_indents);
4578        }
4579
4580        result
4581    }
4582
4583    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4584        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4585            let mut size = buffer.indent_size_for_line(range.start.row);
4586            size.len = size
4587                .len
4588                .min(range.end.column)
4589                .saturating_sub(range.start.column);
4590            size
4591        } else {
4592            IndentSize::spaces(0)
4593        }
4594    }
4595
4596    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4597        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4598            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4599        } else {
4600            LineIndent::spaces(0)
4601        }
4602    }
4603
4604    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4605        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4606
4607        if self.language_settings(cx).extend_comment_on_newline
4608            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4609        {
4610            let delimiters = language_scope.line_comment_prefixes();
4611            for delimiter in delimiters {
4612                if *self
4613                    .chars_at(Point::new(row.0, indent.len() as u32))
4614                    .take(delimiter.chars().count())
4615                    .collect::<String>()
4616                    .as_str()
4617                    == **delimiter
4618                {
4619                    indent.push_str(delimiter);
4620                    break;
4621                }
4622            }
4623        }
4624
4625        indent
4626    }
4627
4628    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4629    where
4630        T: ToOffset,
4631    {
4632        for char in self.reversed_chars_at(position) {
4633            if !char.is_whitespace() {
4634                return false;
4635            }
4636            if char == '\n' {
4637                return true;
4638            }
4639        }
4640        true
4641    }
4642
4643    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4644        while row.0 > 0 {
4645            row.0 -= 1;
4646            if !self.is_line_blank(row) {
4647                return Some(row);
4648            }
4649        }
4650        None
4651    }
4652
4653    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4654        if let Some((_, range)) = self.buffer_line_for_row(row) {
4655            range.end.column - range.start.column
4656        } else {
4657            0
4658        }
4659    }
4660
4661    pub fn buffer_line_for_row(
4662        &self,
4663        row: MultiBufferRow,
4664    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4665        let mut cursor = self.cursor::<Point>();
4666        let point = Point::new(row.0, 0);
4667        cursor.seek(&point);
4668        let region = cursor.region()?;
4669        let overshoot = point.min(region.range.end) - region.range.start;
4670        let buffer_point = region.buffer_range.start + overshoot;
4671        if buffer_point.row > region.buffer_range.end.row {
4672            return None;
4673        }
4674        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4675        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4676            .min(region.buffer_range.end);
4677        Some((region.buffer, line_start..line_end))
4678    }
4679
4680    pub fn max_point(&self) -> Point {
4681        self.text_summary().lines
4682    }
4683
4684    pub fn max_row(&self) -> MultiBufferRow {
4685        MultiBufferRow(self.text_summary().lines.row)
4686    }
4687
4688    pub fn text_summary(&self) -> TextSummary {
4689        self.diff_transforms.summary().output
4690    }
4691
4692    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4693    where
4694        D: TextDimension,
4695        O: ToOffset,
4696    {
4697        let range = range.start.to_offset(self)..range.end.to_offset(self);
4698        let mut cursor = self
4699            .diff_transforms
4700            .cursor::<Dimensions<usize, ExcerptOffset>>(());
4701        cursor.seek(&range.start, Bias::Right);
4702
4703        let Some(first_transform) = cursor.item() else {
4704            return D::from_text_summary(&TextSummary::default());
4705        };
4706
4707        let diff_transform_start = cursor.start().0;
4708        let diff_transform_end = cursor.end().0;
4709        let diff_start = range.start;
4710        let start_overshoot = diff_start - diff_transform_start;
4711        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4712
4713        let mut result = match first_transform {
4714            DiffTransform::BufferContent { .. } => {
4715                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4716                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4717                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4718            }
4719            DiffTransform::DeletedHunk {
4720                buffer_id,
4721                base_text_byte_range,
4722                has_trailing_newline,
4723                ..
4724            } => {
4725                let buffer_start = base_text_byte_range.start + start_overshoot;
4726                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4727                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4728                    panic!("{:?} is in non-existent deleted hunk", range.start)
4729                };
4730
4731                let include_trailing_newline =
4732                    *has_trailing_newline && range.end >= diff_transform_end;
4733                if include_trailing_newline {
4734                    buffer_end -= 1;
4735                }
4736
4737                let mut summary =
4738                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4739
4740                if include_trailing_newline {
4741                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4742                }
4743
4744                summary
4745            }
4746        };
4747        if range.end < diff_transform_end {
4748            return result;
4749        }
4750
4751        cursor.next();
4752        result.add_assign(&D::from_text_summary(
4753            &cursor.summary(&range.end, Bias::Right),
4754        ));
4755
4756        let Some(last_transform) = cursor.item() else {
4757            return result;
4758        };
4759
4760        let overshoot = range.end - cursor.start().0;
4761        let suffix = match last_transform {
4762            DiffTransform::BufferContent { .. } => {
4763                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4764                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4765            }
4766            DiffTransform::DeletedHunk {
4767                base_text_byte_range,
4768                buffer_id,
4769                has_trailing_newline,
4770                ..
4771            } => {
4772                let buffer_end = base_text_byte_range.start + overshoot;
4773                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4774                    panic!("{:?} is in non-existent deleted hunk", range.end)
4775                };
4776
4777                let mut suffix = base_text
4778                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4779                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4780                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4781                }
4782                suffix
4783            }
4784        };
4785
4786        result.add_assign(&suffix);
4787        result
4788    }
4789
4790    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4791    where
4792        D: TextDimension,
4793    {
4794        let mut summary = D::zero(());
4795        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
4796        cursor.seek(&range.start, Bias::Right);
4797        if let Some(excerpt) = cursor.item() {
4798            let mut end_before_newline = cursor.end();
4799            if excerpt.has_trailing_newline {
4800                end_before_newline -= ExcerptOffset::new(1);
4801            }
4802
4803            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4804            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4805            let end_in_excerpt =
4806                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4807            summary.add_assign(
4808                &excerpt
4809                    .buffer
4810                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4811            );
4812
4813            if range.end > end_before_newline {
4814                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4815            }
4816
4817            cursor.next();
4818        }
4819
4820        if range.end > *cursor.start() {
4821            summary.add_assign(
4822                &cursor
4823                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right)
4824                    .0,
4825            );
4826            if let Some(excerpt) = cursor.item() {
4827                range.end = cmp::max(*cursor.start(), range.end);
4828
4829                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4830                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4831                summary.add_assign(
4832                    &excerpt
4833                        .buffer
4834                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4835                );
4836            }
4837        }
4838
4839        summary
4840    }
4841
4842    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4843    where
4844        D: TextDimension + Ord + Sub<D, Output = D>,
4845    {
4846        self.summaries_for_anchors([anchor])[0]
4847    }
4848
4849    fn resolve_summary_for_anchor<D>(
4850        &self,
4851        anchor: &Anchor,
4852        excerpt_position: D,
4853        diff_transforms: &mut Cursor<
4854            DiffTransform,
4855            Dimensions<ExcerptDimension<D>, OutputDimension<D>>,
4856        >,
4857    ) -> D
4858    where
4859        D: TextDimension + Ord + Sub<D, Output = D>,
4860    {
4861        loop {
4862            let transform_end_position = diff_transforms.end().0.0;
4863            let at_transform_end =
4864                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4865            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4866                diff_transforms.next();
4867                continue;
4868            }
4869
4870            let mut position = diff_transforms.start().1.0;
4871            match diff_transforms.item() {
4872                Some(DiffTransform::DeletedHunk {
4873                    buffer_id,
4874                    base_text_byte_range,
4875                    ..
4876                }) => {
4877                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
4878                        && let Some(base_text) =
4879                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4880                        && base_text.can_resolve(diff_base_anchor)
4881                    {
4882                        let base_text_offset = diff_base_anchor.to_offset(base_text);
4883                        if base_text_offset >= base_text_byte_range.start
4884                            && base_text_offset <= base_text_byte_range.end
4885                        {
4886                            let position_in_hunk = base_text.text_summary_for_range::<D, _>(
4887                                base_text_byte_range.start..base_text_offset,
4888                            );
4889                            position.add_assign(&position_in_hunk);
4890                        } else if at_transform_end {
4891                            diff_transforms.next();
4892                            continue;
4893                        }
4894                    }
4895                }
4896                _ => {
4897                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4898                        diff_transforms.next();
4899                        continue;
4900                    }
4901                    let overshoot = excerpt_position - diff_transforms.start().0.0;
4902                    position.add_assign(&overshoot);
4903                }
4904            }
4905
4906            return position;
4907        }
4908    }
4909
4910    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4911        let mut cursor = self
4912            .excerpts
4913            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
4914        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4915
4916        cursor.seek(&Some(locator), Bias::Left);
4917        if cursor.item().is_none() && anchor.excerpt_id == ExcerptId::max() {
4918            cursor.prev();
4919        }
4920
4921        let mut position = cursor.start().1;
4922        if let Some(excerpt) = cursor.item()
4923            && (excerpt.id == anchor.excerpt_id || anchor.excerpt_id == ExcerptId::max())
4924        {
4925            let excerpt_buffer_start = excerpt
4926                .buffer
4927                .offset_for_anchor(&excerpt.range.context.start);
4928            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4929            let buffer_position = cmp::min(
4930                excerpt_buffer_end,
4931                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4932            );
4933            if buffer_position > excerpt_buffer_start {
4934                position.value += buffer_position - excerpt_buffer_start;
4935            }
4936        }
4937        position
4938    }
4939
4940    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
4941        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
4942            excerpt_id = *replacement;
4943        }
4944        excerpt_id
4945    }
4946
4947    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4948    where
4949        D: TextDimension + Ord + Sub<D, Output = D>,
4950        I: 'a + IntoIterator<Item = &'a Anchor>,
4951    {
4952        let mut anchors = anchors.into_iter().peekable();
4953        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
4954        let mut diff_transforms_cursor = self
4955            .diff_transforms
4956            .cursor::<Dimensions<ExcerptDimension<D>, OutputDimension<D>>>(());
4957        diff_transforms_cursor.next();
4958
4959        let mut summaries = Vec::new();
4960        while let Some(anchor) = anchors.peek() {
4961            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
4962            let excerpt_anchors = iter::from_fn(|| {
4963                let anchor = anchors.peek()?;
4964                if self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id {
4965                    Some(anchors.next().unwrap())
4966                } else {
4967                    None
4968                }
4969            });
4970
4971            let locator = self.excerpt_locator_for_id(excerpt_id);
4972            cursor.seek_forward(locator, Bias::Left);
4973            if cursor.item().is_none() {
4974                cursor.next();
4975            }
4976
4977            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4978            if let Some(excerpt) = cursor.item() {
4979                if excerpt.id != excerpt_id {
4980                    let position = self.resolve_summary_for_anchor(
4981                        &Anchor::min(),
4982                        excerpt_start_position,
4983                        &mut diff_transforms_cursor,
4984                    );
4985                    summaries.extend(excerpt_anchors.map(|_| position));
4986                    continue;
4987                }
4988                let excerpt_buffer_start =
4989                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4990                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4991                for (buffer_summary, anchor) in excerpt
4992                    .buffer
4993                    .summaries_for_anchors_with_payload::<D, _, _>(
4994                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
4995                    )
4996                {
4997                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
4998                    let mut position = excerpt_start_position;
4999                    if summary > excerpt_buffer_start {
5000                        position.add_assign(&(summary - excerpt_buffer_start));
5001                    }
5002
5003                    if position > diff_transforms_cursor.start().0.0 {
5004                        diff_transforms_cursor
5005                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5006                    }
5007
5008                    summaries.push(self.resolve_summary_for_anchor(
5009                        anchor,
5010                        position,
5011                        &mut diff_transforms_cursor,
5012                    ));
5013                }
5014            } else {
5015                diff_transforms_cursor
5016                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5017                let position = self.resolve_summary_for_anchor(
5018                    &Anchor::max(),
5019                    excerpt_start_position,
5020                    &mut diff_transforms_cursor,
5021                );
5022                summaries.extend(excerpt_anchors.map(|_| position));
5023            }
5024        }
5025
5026        summaries
5027    }
5028
5029    pub fn dimensions_from_points<'a, D>(
5030        &'a self,
5031        points: impl 'a + IntoIterator<Item = Point>,
5032    ) -> impl 'a + Iterator<Item = D>
5033    where
5034        D: TextDimension + Sub<D, Output = D>,
5035    {
5036        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5037        cursor.seek(&DimensionPair {
5038            key: Point::default(),
5039            value: None,
5040        });
5041        let mut points = points.into_iter();
5042        iter::from_fn(move || {
5043            let point = points.next()?;
5044
5045            cursor.seek_forward(&DimensionPair {
5046                key: point,
5047                value: None,
5048            });
5049
5050            if let Some(region) = cursor.region() {
5051                let overshoot = point - region.range.start.key;
5052                let buffer_point = region.buffer_range.start.key + overshoot;
5053                let mut position = region.range.start.value.unwrap();
5054                position.add_assign(
5055                    &region
5056                        .buffer
5057                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5058                );
5059                if point == region.range.end.key && region.has_trailing_newline {
5060                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5061                }
5062                Some(position)
5063            } else {
5064                Some(D::from_text_summary(&self.text_summary()))
5065            }
5066        })
5067    }
5068
5069    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5070    where
5071        I: 'a + IntoIterator<Item = &'a Anchor>,
5072    {
5073        let mut anchors = anchors.into_iter().enumerate().peekable();
5074        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5075        cursor.next();
5076
5077        let mut result = Vec::new();
5078
5079        while let Some((_, anchor)) = anchors.peek() {
5080            let old_excerpt_id = anchor.excerpt_id;
5081
5082            // Find the location where this anchor's excerpt should be.
5083            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5084            cursor.seek_forward(&Some(old_locator), Bias::Left);
5085
5086            let next_excerpt = cursor.item();
5087            let prev_excerpt = cursor.prev_item();
5088
5089            // Process all of the anchors for this excerpt.
5090            while let Some((anchor_ix, &anchor)) =
5091                anchors.next_if(|(_, anchor)| anchor.excerpt_id == old_excerpt_id)
5092            {
5093                let mut anchor = anchor;
5094
5095                // Leave min and max anchors unchanged if invalid or
5096                // if the old excerpt still exists at this location
5097                let mut kept_position = next_excerpt
5098                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5099                    || old_excerpt_id == ExcerptId::max()
5100                    || old_excerpt_id == ExcerptId::min();
5101
5102                // If the old excerpt no longer exists at this location, then attempt to
5103                // find an equivalent position for this anchor in an adjacent excerpt.
5104                if !kept_position {
5105                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5106                        if excerpt.contains(&anchor) {
5107                            anchor.excerpt_id = excerpt.id;
5108                            kept_position = true;
5109                            break;
5110                        }
5111                    }
5112                }
5113
5114                // If there's no adjacent excerpt that contains the anchor's position,
5115                // then report that the anchor has lost its position.
5116                if !kept_position {
5117                    anchor = if let Some(excerpt) = next_excerpt {
5118                        let mut text_anchor = excerpt
5119                            .range
5120                            .context
5121                            .start
5122                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5123                        if text_anchor
5124                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5125                            .is_gt()
5126                        {
5127                            text_anchor = excerpt.range.context.end;
5128                        }
5129                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5130                    } else if let Some(excerpt) = prev_excerpt {
5131                        let mut text_anchor = excerpt
5132                            .range
5133                            .context
5134                            .end
5135                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5136                        if text_anchor
5137                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5138                            .is_lt()
5139                        {
5140                            text_anchor = excerpt.range.context.start;
5141                        }
5142                        Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor)
5143                    } else if anchor.text_anchor.bias == Bias::Left {
5144                        Anchor::min()
5145                    } else {
5146                        Anchor::max()
5147                    };
5148                }
5149
5150                result.push((anchor_ix, anchor, kept_position));
5151            }
5152        }
5153        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5154        result
5155    }
5156
5157    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5158        self.anchor_at(position, Bias::Left)
5159    }
5160
5161    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5162        self.anchor_at(position, Bias::Right)
5163    }
5164
5165    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5166        let offset = position.to_offset(self);
5167
5168        // Find the given position in the diff transforms. Determine the corresponding
5169        // offset in the excerpts, and whether the position is within a deleted hunk.
5170        let mut diff_transforms = self
5171            .diff_transforms
5172            .cursor::<Dimensions<usize, ExcerptOffset>>(());
5173        diff_transforms.seek(&offset, Bias::Right);
5174
5175        if offset == diff_transforms.start().0
5176            && bias == Bias::Left
5177            && let Some(prev_item) = diff_transforms.prev_item()
5178            && let DiffTransform::DeletedHunk { .. } = prev_item
5179        {
5180            diff_transforms.prev();
5181        }
5182        let offset_in_transform = offset - diff_transforms.start().0;
5183        let mut excerpt_offset = diff_transforms.start().1;
5184        let mut diff_base_anchor = None;
5185        if let Some(DiffTransform::DeletedHunk {
5186            buffer_id,
5187            base_text_byte_range,
5188            has_trailing_newline,
5189            ..
5190        }) = diff_transforms.item()
5191        {
5192            let diff = self.diffs.get(buffer_id).expect("missing diff");
5193            if offset_in_transform > base_text_byte_range.len() {
5194                debug_assert!(*has_trailing_newline);
5195                bias = Bias::Right;
5196            } else {
5197                diff_base_anchor = Some(
5198                    diff.base_text()
5199                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5200                );
5201                bias = Bias::Left;
5202            }
5203        } else {
5204            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5205        };
5206
5207        let mut excerpts = self
5208            .excerpts
5209            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5210        excerpts.seek(&excerpt_offset, Bias::Right);
5211        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5212            excerpts.prev();
5213        }
5214        if let Some(excerpt) = excerpts.item() {
5215            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5216            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5217                overshoot -= 1;
5218                bias = Bias::Right;
5219            }
5220
5221            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5222            let text_anchor =
5223                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5224            let anchor = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, text_anchor);
5225            match diff_base_anchor {
5226                Some(diff_base_anchor) => anchor.with_diff_base_anchor(diff_base_anchor),
5227                None => anchor,
5228            }
5229        } else if excerpt_offset.is_zero() && bias == Bias::Left {
5230            Anchor::min()
5231        } else {
5232            Anchor::max()
5233        }
5234    }
5235
5236    /// Returns an anchor for the given excerpt and text anchor,
5237    /// returns None if the excerpt_id is no longer valid.
5238    pub fn anchor_in_excerpt(
5239        &self,
5240        excerpt_id: ExcerptId,
5241        text_anchor: text::Anchor,
5242    ) -> Option<Anchor> {
5243        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5244        let excerpt = self.excerpt(excerpt_id)?;
5245        Some(Anchor::in_buffer(
5246            excerpt_id,
5247            excerpt.buffer_id,
5248            text_anchor,
5249        ))
5250    }
5251
5252    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5253        Some(self.excerpt(excerpt_id)?.range.context.clone())
5254    }
5255
5256    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5257        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5258            true
5259        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5260            excerpt.buffer.can_resolve(&anchor.text_anchor)
5261        } else {
5262            false
5263        }
5264    }
5265
5266    pub fn excerpts(
5267        &self,
5268    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5269        self.excerpts
5270            .iter()
5271            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5272    }
5273
5274    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5275        let excerpts = self.excerpts.cursor(());
5276        let diff_transforms = self.diff_transforms.cursor(());
5277        MultiBufferCursor {
5278            excerpts,
5279            diff_transforms,
5280            diffs: &self.diffs,
5281            cached_region: None,
5282        }
5283    }
5284
5285    pub fn excerpt_before(&self, excerpt_id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5286        let start_locator = self.excerpt_locator_for_id(excerpt_id);
5287        let mut excerpts = self
5288            .excerpts
5289            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(());
5290        excerpts.seek(&Some(start_locator), Bias::Left);
5291        excerpts.prev();
5292
5293        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(());
5294        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5295        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5296            diff_transforms.next();
5297        }
5298
5299        let excerpt = excerpts.item()?;
5300        Some(MultiBufferExcerpt {
5301            excerpt,
5302            offset: diff_transforms.start().output_dimension.0,
5303            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5304            excerpt_offset: excerpts.start().1.clone(),
5305            diff_transforms,
5306        })
5307    }
5308
5309    pub fn excerpt_boundaries_in_range<R, T>(
5310        &self,
5311        range: R,
5312    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5313    where
5314        R: RangeBounds<T>,
5315        T: ToOffset,
5316    {
5317        let start_offset;
5318        let start = match range.start_bound() {
5319            Bound::Included(start) => {
5320                start_offset = start.to_offset(self);
5321                Bound::Included(start_offset)
5322            }
5323            Bound::Excluded(_) => {
5324                panic!("not supported")
5325            }
5326            Bound::Unbounded => {
5327                start_offset = 0;
5328                Bound::Unbounded
5329            }
5330        };
5331        let end = match range.end_bound() {
5332            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5333            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5334            Bound::Unbounded => Bound::Unbounded,
5335        };
5336        let bounds = (start, end);
5337
5338        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5339        cursor.seek(&DimensionPair {
5340            key: start_offset,
5341            value: None,
5342        });
5343
5344        if cursor
5345            .region()
5346            .is_some_and(|region| bounds.contains(&region.range.start.key))
5347        {
5348            cursor.prev_excerpt();
5349        } else {
5350            cursor.seek_to_start_of_current_excerpt();
5351        }
5352        let mut prev_region = cursor.region();
5353
5354        cursor.next_excerpt();
5355
5356        iter::from_fn(move || {
5357            loop {
5358                if self.singleton {
5359                    return None;
5360                }
5361
5362                let next_region = cursor.region()?;
5363                cursor.next_excerpt();
5364                if !bounds.contains(&next_region.range.start.key) {
5365                    prev_region = Some(next_region);
5366                    continue;
5367                }
5368
5369                let next_region_start = next_region.range.start.value.unwrap();
5370                let next_region_end = if let Some(region) = cursor.region() {
5371                    region.range.start.value.unwrap()
5372                } else {
5373                    self.max_point()
5374                };
5375
5376                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5377                    id: region.excerpt.id,
5378                    buffer: region.excerpt.buffer.clone(),
5379                    buffer_id: region.excerpt.buffer_id,
5380                    range: region.excerpt.range.clone(),
5381                    end_row: MultiBufferRow(next_region_start.row),
5382                });
5383
5384                let next = ExcerptInfo {
5385                    id: next_region.excerpt.id,
5386                    buffer: next_region.excerpt.buffer.clone(),
5387                    buffer_id: next_region.excerpt.buffer_id,
5388                    range: next_region.excerpt.range.clone(),
5389                    end_row: if next_region.excerpt.has_trailing_newline {
5390                        MultiBufferRow(next_region_end.row - 1)
5391                    } else {
5392                        MultiBufferRow(next_region_end.row)
5393                    },
5394                };
5395
5396                let row = MultiBufferRow(next_region_start.row);
5397
5398                prev_region = Some(next_region);
5399
5400                return Some(ExcerptBoundary { row, prev, next });
5401            }
5402        })
5403    }
5404
5405    pub fn edit_count(&self) -> usize {
5406        self.edit_count
5407    }
5408
5409    pub fn non_text_state_update_count(&self) -> usize {
5410        self.non_text_state_update_count
5411    }
5412
5413    /// Returns the smallest enclosing bracket ranges containing the given range or
5414    /// None if no brackets contain range or the range is not contained in a single
5415    /// excerpt
5416    ///
5417    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5418    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5419        &self,
5420        range: Range<T>,
5421        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5422    ) -> Option<(Range<usize>, Range<usize>)> {
5423        let range = range.start.to_offset(self)..range.end.to_offset(self);
5424        let mut excerpt = self.excerpt_containing(range.clone())?;
5425        let buffer = excerpt.buffer();
5426        let excerpt_buffer_range = excerpt.buffer_range();
5427
5428        // Filter to ranges contained in the excerpt
5429        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5430            excerpt_buffer_range.contains(&open.start)
5431                && excerpt_buffer_range.contains(&close.end)
5432                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5433        };
5434
5435        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5436            excerpt.map_range_to_buffer(range),
5437            Some(&range_filter),
5438        )?;
5439
5440        Some((
5441            excerpt.map_range_from_buffer(open),
5442            excerpt.map_range_from_buffer(close),
5443        ))
5444    }
5445
5446    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5447    /// not contained in a single excerpt
5448    pub fn enclosing_bracket_ranges<T: ToOffset>(
5449        &self,
5450        range: Range<T>,
5451    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5452        let range = range.start.to_offset(self)..range.end.to_offset(self);
5453        let mut excerpt = self.excerpt_containing(range.clone())?;
5454
5455        Some(
5456            excerpt
5457                .buffer()
5458                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5459                .filter_map(move |pair| {
5460                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5461                        Some((
5462                            excerpt.map_range_from_buffer(pair.open_range),
5463                            excerpt.map_range_from_buffer(pair.close_range),
5464                        ))
5465                    } else {
5466                        None
5467                    }
5468                }),
5469        )
5470    }
5471
5472    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5473    /// not contained in a single excerpt
5474    pub fn text_object_ranges<T: ToOffset>(
5475        &self,
5476        range: Range<T>,
5477        options: TreeSitterOptions,
5478    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5479        let range = range.start.to_offset(self)..range.end.to_offset(self);
5480        self.excerpt_containing(range.clone())
5481            .map(|mut excerpt| {
5482                excerpt
5483                    .buffer()
5484                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5485                    .filter_map(move |(range, text_object)| {
5486                        if excerpt.contains_buffer_range(range.clone()) {
5487                            Some((excerpt.map_range_from_buffer(range), text_object))
5488                        } else {
5489                            None
5490                        }
5491                    })
5492            })
5493            .into_iter()
5494            .flatten()
5495    }
5496
5497    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5498    /// not contained in a single excerpt
5499    pub fn bracket_ranges<T: ToOffset>(
5500        &self,
5501        range: Range<T>,
5502    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5503        let range = range.start.to_offset(self)..range.end.to_offset(self);
5504        let mut excerpt = self.excerpt_containing(range.clone())?;
5505
5506        Some(
5507            excerpt
5508                .buffer()
5509                .bracket_ranges(excerpt.map_range_to_buffer(range))
5510                .filter_map(move |pair| {
5511                    let buffer_range = pair.open_range.start..pair.close_range.end;
5512                    if excerpt.contains_buffer_range(buffer_range) {
5513                        Some((
5514                            excerpt.map_range_from_buffer(pair.open_range),
5515                            excerpt.map_range_from_buffer(pair.close_range),
5516                        ))
5517                    } else {
5518                        None
5519                    }
5520                }),
5521        )
5522    }
5523
5524    pub fn redacted_ranges<'a, T: ToOffset>(
5525        &'a self,
5526        range: Range<T>,
5527        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5528    ) -> impl Iterator<Item = Range<usize>> + 'a {
5529        let range = range.start.to_offset(self)..range.end.to_offset(self);
5530        self.lift_buffer_metadata(range, move |buffer, range| {
5531            if redaction_enabled(buffer.file()) {
5532                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5533            } else {
5534                None
5535            }
5536        })
5537        .map(|(range, _, _)| range)
5538    }
5539
5540    pub fn runnable_ranges(
5541        &self,
5542        range: Range<Anchor>,
5543    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5544        let range = range.start.to_offset(self)..range.end.to_offset(self);
5545        self.lift_buffer_metadata(range, move |buffer, range| {
5546            Some(
5547                buffer
5548                    .runnable_ranges(range.clone())
5549                    .filter(move |runnable| {
5550                        runnable.run_range.start >= range.start
5551                            && runnable.run_range.end < range.end
5552                    })
5553                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5554            )
5555        })
5556        .map(|(run_range, runnable, _)| language::RunnableRange {
5557            run_range,
5558            ..runnable
5559        })
5560    }
5561
5562    pub fn line_indents(
5563        &self,
5564        start_row: MultiBufferRow,
5565        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5566    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5567        let max_point = self.max_point();
5568        let mut cursor = self.cursor::<Point>();
5569        cursor.seek(&Point::new(start_row.0, 0));
5570        iter::from_fn(move || {
5571            let mut region = cursor.region()?;
5572            while !buffer_filter(&region.excerpt.buffer) {
5573                cursor.next();
5574                region = cursor.region()?;
5575            }
5576            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5577            let buffer_start_row =
5578                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5579
5580            let buffer_end_row = if region.is_main_buffer
5581                && (region.has_trailing_newline || region.range.end == max_point)
5582            {
5583                region.buffer_range.end.row
5584            } else {
5585                region.buffer_range.end.row.saturating_sub(1)
5586            };
5587
5588            let line_indents = region
5589                .buffer
5590                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5591            cursor.next();
5592            Some(line_indents.map(move |(buffer_row, indent)| {
5593                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5594                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5595            }))
5596        })
5597        .flatten()
5598    }
5599
5600    pub fn reversed_line_indents(
5601        &self,
5602        end_row: MultiBufferRow,
5603        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5604    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5605        let max_point = self.max_point();
5606        let mut cursor = self.cursor::<Point>();
5607        cursor.seek(&Point::new(end_row.0, 0));
5608        iter::from_fn(move || {
5609            let mut region = cursor.region()?;
5610            while !buffer_filter(&region.excerpt.buffer) {
5611                cursor.prev();
5612                region = cursor.region()?;
5613            }
5614
5615            let buffer_start_row = region.buffer_range.start.row;
5616            let buffer_end_row = if region.is_main_buffer
5617                && (region.has_trailing_newline || region.range.end == max_point)
5618            {
5619                region.buffer_range.end.row + 1
5620            } else {
5621                region.buffer_range.end.row
5622            };
5623
5624            let overshoot = end_row.0 - region.range.start.row;
5625            let buffer_end_row =
5626                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5627
5628            let line_indents = region
5629                .buffer
5630                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5631            cursor.prev();
5632            Some(line_indents.map(move |(buffer_row, indent)| {
5633                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5634                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5635            }))
5636        })
5637        .flatten()
5638    }
5639
5640    pub async fn enclosing_indent(
5641        &self,
5642        mut target_row: MultiBufferRow,
5643    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5644        let max_row = MultiBufferRow(self.max_point().row);
5645        if target_row >= max_row {
5646            return None;
5647        }
5648
5649        let mut target_indent = self.line_indent_for_row(target_row);
5650
5651        // If the current row is at the start of an indented block, we want to return this
5652        // block as the enclosing indent.
5653        if !target_indent.is_line_empty() && target_row < max_row {
5654            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5655            if !next_line_indent.is_line_empty()
5656                && target_indent.raw_len() < next_line_indent.raw_len()
5657            {
5658                target_indent = next_line_indent;
5659                target_row.0 += 1;
5660            }
5661        }
5662
5663        const SEARCH_ROW_LIMIT: u32 = 25000;
5664        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5665        const YIELD_INTERVAL: u32 = 100;
5666
5667        let mut accessed_row_counter = 0;
5668
5669        // If there is a blank line at the current row, search for the next non indented lines
5670        if target_indent.is_line_empty() {
5671            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5672            let end =
5673                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5674
5675            let mut non_empty_line_above = None;
5676            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5677                if row < start {
5678                    break;
5679                }
5680                accessed_row_counter += 1;
5681                if accessed_row_counter == YIELD_INTERVAL {
5682                    accessed_row_counter = 0;
5683                    yield_now().await;
5684                }
5685                if !indent.is_line_empty() {
5686                    non_empty_line_above = Some((row, indent));
5687                    break;
5688                }
5689            }
5690
5691            let mut non_empty_line_below = None;
5692            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5693                if row > end {
5694                    break;
5695                }
5696                accessed_row_counter += 1;
5697                if accessed_row_counter == YIELD_INTERVAL {
5698                    accessed_row_counter = 0;
5699                    yield_now().await;
5700                }
5701                if !indent.is_line_empty() {
5702                    non_empty_line_below = Some((row, indent));
5703                    break;
5704                }
5705            }
5706
5707            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5708                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5709                    if above_indent.raw_len() >= below_indent.raw_len() {
5710                        (above_row, above_indent)
5711                    } else {
5712                        (below_row, below_indent)
5713                    }
5714                }
5715                (Some(above), None) => above,
5716                (None, Some(below)) => below,
5717                _ => return None,
5718            };
5719
5720            target_indent = indent;
5721            target_row = row;
5722        }
5723
5724        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5725        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5726
5727        let mut start_indent = None;
5728        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5729            if row < start {
5730                break;
5731            }
5732            accessed_row_counter += 1;
5733            if accessed_row_counter == YIELD_INTERVAL {
5734                accessed_row_counter = 0;
5735                yield_now().await;
5736            }
5737            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5738                start_indent = Some((row, indent));
5739                break;
5740            }
5741        }
5742        let (start_row, start_indent_size) = start_indent?;
5743
5744        let mut end_indent = (end, None);
5745        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5746            if row > end {
5747                break;
5748            }
5749            accessed_row_counter += 1;
5750            if accessed_row_counter == YIELD_INTERVAL {
5751                accessed_row_counter = 0;
5752                yield_now().await;
5753            }
5754            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5755                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5756                break;
5757            }
5758        }
5759        let (end_row, end_indent_size) = end_indent;
5760
5761        let indent = if let Some(end_indent_size) = end_indent_size {
5762            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5763                start_indent_size
5764            } else {
5765                end_indent_size
5766            }
5767        } else {
5768            start_indent_size
5769        };
5770
5771        Some((start_row..end_row, indent))
5772    }
5773
5774    pub fn indent_guides_in_range<T: ToPoint>(
5775        &self,
5776        range: Range<T>,
5777        ignore_disabled_for_language: bool,
5778        cx: &App,
5779    ) -> impl Iterator<Item = IndentGuide> {
5780        let range = range.start.to_point(self)..range.end.to_point(self);
5781        let start_row = MultiBufferRow(range.start.row);
5782        let end_row = MultiBufferRow(range.end.row);
5783
5784        let mut row_indents = self.line_indents(start_row, |buffer| {
5785            let settings =
5786                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5787            settings.indent_guides.enabled || ignore_disabled_for_language
5788        });
5789
5790        let mut result = Vec::new();
5791        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5792
5793        let mut prev_settings = None;
5794        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5795            if first_row > end_row {
5796                break;
5797            }
5798            let current_depth = indent_stack.len() as u32;
5799
5800            // Avoid retrieving the language settings repeatedly for every buffer row.
5801            if let Some((prev_buffer_id, _)) = &prev_settings
5802                && prev_buffer_id != &buffer.remote_id()
5803            {
5804                prev_settings.take();
5805            }
5806            let settings = &prev_settings
5807                .get_or_insert_with(|| {
5808                    (
5809                        buffer.remote_id(),
5810                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5811                    )
5812                })
5813                .1;
5814            let tab_size = settings.tab_size.get();
5815
5816            // When encountering empty, continue until found useful line indent
5817            // then add to the indent stack with the depth found
5818            let mut found_indent = false;
5819            let mut last_row = first_row;
5820            if line_indent.is_line_blank() {
5821                while !found_indent {
5822                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5823                        break;
5824                    };
5825                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5826                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5827                        break;
5828                    }
5829
5830                    if new_line_indent.is_line_blank() {
5831                        continue;
5832                    }
5833                    last_row = target_row.min(end_row);
5834                    line_indent = new_line_indent;
5835                    found_indent = true;
5836                    break;
5837                }
5838            } else {
5839                found_indent = true
5840            }
5841
5842            let depth = if found_indent {
5843                line_indent.len(tab_size) / tab_size
5844            } else {
5845                0
5846            };
5847
5848            match depth.cmp(&current_depth) {
5849                cmp::Ordering::Less => {
5850                    for _ in 0..(current_depth - depth) {
5851                        let mut indent = indent_stack.pop().unwrap();
5852                        if last_row != first_row {
5853                            // In this case, we landed on an empty row, had to seek forward,
5854                            // and discovered that the indent we where on is ending.
5855                            // This means that the last display row must
5856                            // be on line that ends this indent range, so we
5857                            // should display the range up to the first non-empty line
5858                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5859                        }
5860
5861                        result.push(indent)
5862                    }
5863                }
5864                cmp::Ordering::Greater => {
5865                    for next_depth in current_depth..depth {
5866                        indent_stack.push(IndentGuide {
5867                            buffer_id: buffer.remote_id(),
5868                            start_row: first_row,
5869                            end_row: last_row,
5870                            depth: next_depth,
5871                            tab_size,
5872                            settings: settings.indent_guides.clone(),
5873                        });
5874                    }
5875                }
5876                _ => {}
5877            }
5878
5879            for indent in indent_stack.iter_mut() {
5880                indent.end_row = last_row;
5881            }
5882        }
5883
5884        result.extend(indent_stack);
5885        result.into_iter()
5886    }
5887
5888    pub fn trailing_excerpt_update_count(&self) -> usize {
5889        self.trailing_excerpt_update_count
5890    }
5891
5892    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5893        self.point_to_buffer_offset(point)
5894            .and_then(|(buffer, _)| buffer.file())
5895    }
5896
5897    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5898        self.point_to_buffer_offset(point)
5899            .and_then(|(buffer, offset)| buffer.language_at(offset))
5900    }
5901
5902    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5903        self.excerpts
5904            .first()
5905            .map(|excerpt| &excerpt.buffer)
5906            .map(|buffer| {
5907                language_settings(
5908                    buffer.language().map(|language| language.name()),
5909                    buffer.file(),
5910                    cx,
5911                )
5912            })
5913            .unwrap_or_else(move || self.language_settings_at(0, cx))
5914    }
5915
5916    pub fn language_settings_at<'a, T: ToOffset>(
5917        &'a self,
5918        point: T,
5919        cx: &'a App,
5920    ) -> Cow<'a, LanguageSettings> {
5921        let mut language = None;
5922        let mut file = None;
5923        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5924            language = buffer.language_at(offset);
5925            file = buffer.file();
5926        }
5927        language_settings(language.map(|l| l.name()), file, cx)
5928    }
5929
5930    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5931        self.point_to_buffer_offset(point)
5932            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5933    }
5934
5935    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5936        self.point_to_buffer_offset(point)
5937            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5938            .unwrap_or_default()
5939    }
5940
5941    pub fn language_indent_size_at<T: ToOffset>(
5942        &self,
5943        position: T,
5944        cx: &App,
5945    ) -> Option<IndentSize> {
5946        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5947        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5948    }
5949
5950    pub fn is_dirty(&self) -> bool {
5951        self.is_dirty
5952    }
5953
5954    pub fn has_deleted_file(&self) -> bool {
5955        self.has_deleted_file
5956    }
5957
5958    pub fn has_conflict(&self) -> bool {
5959        self.has_conflict
5960    }
5961
5962    pub fn has_diagnostics(&self) -> bool {
5963        self.excerpts
5964            .iter()
5965            .any(|excerpt| excerpt.buffer.has_diagnostics())
5966    }
5967
5968    pub fn diagnostic_group(
5969        &self,
5970        buffer_id: BufferId,
5971        group_id: usize,
5972    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
5973        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
5974            if buffer.remote_id() != buffer_id {
5975                return None;
5976            };
5977            Some(
5978                buffer
5979                    .diagnostics_in_range(range, false)
5980                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
5981                    .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
5982            )
5983        })
5984        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
5985    }
5986
5987    pub fn diagnostics_in_range<'a, T>(
5988        &'a self,
5989        range: Range<T>,
5990    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, T>> + 'a
5991    where
5992        T: 'a
5993            + text::ToOffset
5994            + text::FromAnchor
5995            + TextDimension
5996            + Ord
5997            + Sub<T, Output = T>
5998            + fmt::Debug,
5999    {
6000        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6001            Some(
6002                buffer
6003                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6004                    .map(|entry| (entry.range, entry.diagnostic)),
6005            )
6006        })
6007        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6008    }
6009
6010    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6011        &'a self,
6012        range: Range<T>,
6013    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, T>)> + 'a
6014    where
6015        T: 'a
6016            + text::ToOffset
6017            + text::FromAnchor
6018            + TextDimension
6019            + Ord
6020            + Sub<T, Output = T>
6021            + fmt::Debug,
6022    {
6023        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6024            Some(
6025                buffer
6026                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6027                    .map(|entry| (entry.range, entry.diagnostic)),
6028            )
6029        })
6030        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6031    }
6032
6033    pub fn syntax_ancestor<T: ToOffset>(
6034        &self,
6035        range: Range<T>,
6036    ) -> Option<(tree_sitter::Node<'_>, Range<usize>)> {
6037        let range = range.start.to_offset(self)..range.end.to_offset(self);
6038        let mut excerpt = self.excerpt_containing(range.clone())?;
6039        let node = excerpt
6040            .buffer()
6041            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6042        let node_range = node.byte_range();
6043        if !excerpt.contains_buffer_range(node_range.clone()) {
6044            return None;
6045        };
6046        Some((node, excerpt.map_range_from_buffer(node_range)))
6047    }
6048
6049    pub fn syntax_next_sibling<T: ToOffset>(
6050        &self,
6051        range: Range<T>,
6052    ) -> Option<tree_sitter::Node<'_>> {
6053        let range = range.start.to_offset(self)..range.end.to_offset(self);
6054        let mut excerpt = self.excerpt_containing(range.clone())?;
6055        excerpt
6056            .buffer()
6057            .syntax_next_sibling(excerpt.map_range_to_buffer(range))
6058    }
6059
6060    pub fn syntax_prev_sibling<T: ToOffset>(
6061        &self,
6062        range: Range<T>,
6063    ) -> Option<tree_sitter::Node<'_>> {
6064        let range = range.start.to_offset(self)..range.end.to_offset(self);
6065        let mut excerpt = self.excerpt_containing(range.clone())?;
6066        excerpt
6067            .buffer()
6068            .syntax_prev_sibling(excerpt.map_range_to_buffer(range))
6069    }
6070
6071    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6072        let (excerpt_id, _, buffer) = self.as_singleton()?;
6073        let outline = buffer.outline(theme);
6074        Some(Outline::new(
6075            outline
6076                .items
6077                .into_iter()
6078                .flat_map(|item| {
6079                    Some(OutlineItem {
6080                        depth: item.depth,
6081                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6082                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6083                        text: item.text,
6084                        highlight_ranges: item.highlight_ranges,
6085                        name_ranges: item.name_ranges,
6086                        body_range: item.body_range.and_then(|body_range| {
6087                            Some(
6088                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6089                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6090                            )
6091                        }),
6092                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6093                            Some(
6094                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6095                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6096                            )
6097                        }),
6098                    })
6099                })
6100                .collect(),
6101        ))
6102    }
6103
6104    pub fn symbols_containing<T: ToOffset>(
6105        &self,
6106        offset: T,
6107        theme: Option<&SyntaxTheme>,
6108    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6109        let anchor = self.anchor_before(offset);
6110        let excerpt_id = anchor.excerpt_id;
6111        let excerpt = self.excerpt(excerpt_id)?;
6112        let buffer_id = excerpt.buffer_id;
6113        Some((
6114            buffer_id,
6115            excerpt
6116                .buffer
6117                .symbols_containing(anchor.text_anchor, theme)
6118                .into_iter()
6119                .flat_map(|item| {
6120                    Some(OutlineItem {
6121                        depth: item.depth,
6122                        range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
6123                        text: item.text,
6124                        highlight_ranges: item.highlight_ranges,
6125                        name_ranges: item.name_ranges,
6126                        body_range: item.body_range.map(|body_range| {
6127                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6128                        }),
6129                        annotation_range: item.annotation_range.map(|body_range| {
6130                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6131                        }),
6132                    })
6133                })
6134                .collect(),
6135        ))
6136    }
6137
6138    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6139        if id == ExcerptId::min() {
6140            Locator::min_ref()
6141        } else if id == ExcerptId::max() {
6142            Locator::max_ref()
6143        } else {
6144            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6145            cursor.seek(&id, Bias::Left);
6146            if let Some(entry) = cursor.item()
6147                && entry.id == id
6148            {
6149                return &entry.locator;
6150            }
6151            panic!("invalid excerpt id {id:?}")
6152        }
6153    }
6154
6155    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6156    fn excerpt_locators_for_ids(
6157        &self,
6158        ids: impl IntoIterator<Item = ExcerptId>,
6159    ) -> SmallVec<[Locator; 1]> {
6160        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6161        sorted_ids.sort_unstable();
6162        let mut locators = SmallVec::new();
6163
6164        while sorted_ids.last() == Some(&ExcerptId::max()) {
6165            sorted_ids.pop();
6166            if let Some(mapping) = self.excerpt_ids.last() {
6167                locators.push(mapping.locator.clone());
6168            }
6169        }
6170
6171        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6172        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6173            sorted_ids.next();
6174            if let Some(mapping) = self.excerpt_ids.first() {
6175                locators.push(mapping.locator.clone());
6176            }
6177        }
6178
6179        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6180        for id in sorted_ids {
6181            if cursor.seek_forward(&id, Bias::Left) {
6182                locators.push(cursor.item().unwrap().locator.clone());
6183            } else {
6184                panic!("invalid excerpt id {:?}", id);
6185            }
6186        }
6187
6188        locators.sort_unstable();
6189        locators
6190    }
6191
6192    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6193        Some(self.excerpt(excerpt_id)?.buffer_id)
6194    }
6195
6196    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6197        Some(&self.excerpt(excerpt_id)?.buffer)
6198    }
6199
6200    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6201        let mut cursor = self
6202            .excerpts
6203            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
6204        let locator = self.excerpt_locator_for_id(excerpt_id);
6205        let mut sought_exact = cursor.seek(&Some(locator), Bias::Left);
6206        if excerpt_id == ExcerptId::max() {
6207            sought_exact = true;
6208            cursor.prev();
6209        } else if excerpt_id == ExcerptId::min() {
6210            sought_exact = true;
6211        }
6212        if sought_exact {
6213            let start = cursor.start().1.clone();
6214            let end = cursor.end().1;
6215            let mut diff_transforms = self
6216                .diff_transforms
6217                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
6218            diff_transforms.seek(&start, Bias::Left);
6219            let overshoot = start.0 - diff_transforms.start().0.0;
6220            let start = diff_transforms.start().1.0 + overshoot;
6221            diff_transforms.seek(&end, Bias::Right);
6222            let overshoot = end.0 - diff_transforms.start().0.0;
6223            let end = diff_transforms.start().1.0 + overshoot;
6224            Some(start..end)
6225        } else {
6226            None
6227        }
6228    }
6229
6230    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6231        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6232        let locator = self.excerpt_locator_for_id(excerpt_id);
6233        cursor.seek(&Some(locator), Bias::Left);
6234        if let Some(excerpt) = cursor.item()
6235            && excerpt.id == excerpt_id
6236        {
6237            return Some(excerpt);
6238        } else if excerpt_id == ExcerptId::max() {
6239            cursor.prev();
6240            return cursor.item();
6241        }
6242        None
6243    }
6244
6245    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6246    pub fn excerpt_containing<T: ToOffset>(
6247        &self,
6248        range: Range<T>,
6249    ) -> Option<MultiBufferExcerpt<'_>> {
6250        let range = range.start.to_offset(self)..range.end.to_offset(self);
6251        let mut cursor = self.cursor::<usize>();
6252        cursor.seek(&range.start);
6253
6254        let start_excerpt = cursor.excerpt()?;
6255        if range.end != range.start {
6256            cursor.seek_forward(&range.end);
6257            if cursor.excerpt()?.id != start_excerpt.id {
6258                return None;
6259            }
6260        }
6261
6262        cursor.seek_to_start_of_current_excerpt();
6263        let region = cursor.region()?;
6264        let offset = region.range.start;
6265        let buffer_offset = start_excerpt.buffer_start_offset();
6266        let excerpt_offset = cursor.excerpts.start().clone();
6267        Some(MultiBufferExcerpt {
6268            diff_transforms: cursor.diff_transforms,
6269            excerpt: start_excerpt,
6270            offset,
6271            buffer_offset,
6272            excerpt_offset,
6273        })
6274    }
6275
6276    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
6277        if let Some(id) = anchor.buffer_id {
6278            return Some(id);
6279        }
6280        let excerpt = self.excerpt_containing(anchor..anchor)?;
6281        Some(excerpt.buffer_id())
6282    }
6283
6284    pub fn selections_in_range<'a>(
6285        &'a self,
6286        range: &'a Range<Anchor>,
6287        include_local: bool,
6288    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6289        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
6290        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6291        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6292        cursor.seek(start_locator, Bias::Left);
6293        cursor
6294            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6295            .flat_map(move |excerpt| {
6296                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6297                if excerpt.id == range.start.excerpt_id {
6298                    query_range.start = range.start.text_anchor;
6299                }
6300                if excerpt.id == range.end.excerpt_id {
6301                    query_range.end = range.end.text_anchor;
6302                }
6303
6304                excerpt
6305                    .buffer
6306                    .selections_in_range(query_range, include_local)
6307                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6308                        selections.map(move |selection| {
6309                            let mut start =
6310                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.start);
6311                            let mut end =
6312                                Anchor::in_buffer(excerpt.id, excerpt.buffer_id, selection.end);
6313                            if range.start.cmp(&start, self).is_gt() {
6314                                start = range.start;
6315                            }
6316                            if range.end.cmp(&end, self).is_lt() {
6317                                end = range.end;
6318                            }
6319
6320                            (
6321                                replica_id,
6322                                line_mode,
6323                                cursor_shape,
6324                                Selection {
6325                                    id: selection.id,
6326                                    start,
6327                                    end,
6328                                    reversed: selection.reversed,
6329                                    goal: selection.goal,
6330                                },
6331                            )
6332                        })
6333                    })
6334            })
6335    }
6336
6337    pub fn show_headers(&self) -> bool {
6338        self.show_headers
6339    }
6340
6341    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6342        self.diffs.get(&buffer_id)
6343    }
6344
6345    /// Visually annotates a position or range with the `Debug` representation of a value. The
6346    /// callsite of this function is used as a key - previous annotations will be removed.
6347    #[cfg(debug_assertions)]
6348    #[track_caller]
6349    pub fn debug<V, R>(&self, ranges: &R, value: V)
6350    where
6351        R: debug::ToMultiBufferDebugRanges,
6352        V: std::fmt::Debug,
6353    {
6354        self.debug_with_key(std::panic::Location::caller(), ranges, value);
6355    }
6356
6357    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
6358    /// debug annotations with the same key will be removed. The key is also used to determine the
6359    /// annotation's color.
6360    #[cfg(debug_assertions)]
6361    #[track_caller]
6362    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
6363    where
6364        K: std::hash::Hash + 'static,
6365        R: debug::ToMultiBufferDebugRanges,
6366        V: std::fmt::Debug,
6367    {
6368        let text_ranges = ranges
6369            .to_multi_buffer_debug_ranges(self)
6370            .into_iter()
6371            .flat_map(|range| {
6372                self.range_to_buffer_ranges(range).into_iter().map(
6373                    |(buffer, range, _excerpt_id)| {
6374                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
6375                    },
6376                )
6377            })
6378            .collect();
6379        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
6380            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
6381        });
6382    }
6383}
6384
6385#[cfg(any(test, feature = "test-support"))]
6386impl MultiBufferSnapshot {
6387    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6388        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
6389        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
6390        start..end
6391    }
6392
6393    #[cfg(any(test, feature = "test-support"))]
6394    fn check_invariants(&self) {
6395        let excerpts = self.excerpts.items(());
6396        let excerpt_ids = self.excerpt_ids.items(());
6397
6398        for (ix, excerpt) in excerpts.iter().enumerate() {
6399            if ix == 0 {
6400                if excerpt.locator <= Locator::min() {
6401                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6402                }
6403            } else if excerpt.locator <= excerpts[ix - 1].locator {
6404                panic!("excerpts are out-of-order: {:?}", excerpts);
6405            }
6406        }
6407
6408        for (ix, entry) in excerpt_ids.iter().enumerate() {
6409            if ix == 0 {
6410                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6411                    panic!("invalid first excerpt id {:?}", entry.id);
6412                }
6413            } else if entry.id <= excerpt_ids[ix - 1].id {
6414                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6415            }
6416        }
6417
6418        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6419            panic!(
6420                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6421                self.excerpts.summary().text.len,
6422                self.diff_transforms.summary().input,
6423                self.diff_transforms.items(()),
6424            );
6425        }
6426
6427        let mut prev_transform: Option<&DiffTransform> = None;
6428        for item in self.diff_transforms.iter() {
6429            if let DiffTransform::BufferContent {
6430                summary,
6431                inserted_hunk_info,
6432            } = item
6433            {
6434                if let Some(DiffTransform::BufferContent {
6435                    inserted_hunk_info: prev_inserted_hunk_info,
6436                    ..
6437                }) = prev_transform
6438                    && *inserted_hunk_info == *prev_inserted_hunk_info
6439                {
6440                    panic!(
6441                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6442                        self.diff_transforms.items(())
6443                    );
6444                }
6445                if summary.len == 0 && !self.is_empty() {
6446                    panic!("empty buffer content transform");
6447                }
6448            }
6449            prev_transform = Some(item);
6450        }
6451    }
6452}
6453
6454impl<'a, D> MultiBufferCursor<'a, D>
6455where
6456    D: TextDimension + Ord + Sub<D, Output = D>,
6457{
6458    fn seek(&mut self, position: &D) {
6459        self.cached_region.take();
6460        self.diff_transforms
6461            .seek(&OutputDimension(*position), Bias::Right);
6462        if self.diff_transforms.item().is_none()
6463            && *position == self.diff_transforms.start().output_dimension.0
6464        {
6465            self.diff_transforms.prev();
6466        }
6467
6468        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6469        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6470            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6471            excerpt_position.add_assign(&overshoot);
6472        }
6473
6474        self.excerpts
6475            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6476        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6477            self.excerpts.prev();
6478        }
6479    }
6480
6481    fn seek_forward(&mut self, position: &D) {
6482        self.cached_region.take();
6483        self.diff_transforms
6484            .seek_forward(&OutputDimension(*position), Bias::Right);
6485        if self.diff_transforms.item().is_none()
6486            && *position == self.diff_transforms.start().output_dimension.0
6487        {
6488            self.diff_transforms.prev();
6489        }
6490
6491        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6492        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6493        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6494            excerpt_position.add_assign(&overshoot);
6495        }
6496
6497        self.excerpts
6498            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6499        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6500            self.excerpts.prev();
6501        }
6502    }
6503
6504    fn next_excerpt(&mut self) {
6505        self.excerpts.next();
6506        self.seek_to_start_of_current_excerpt();
6507    }
6508
6509    fn prev_excerpt(&mut self) {
6510        self.excerpts.prev();
6511        self.seek_to_start_of_current_excerpt();
6512    }
6513
6514    fn seek_to_start_of_current_excerpt(&mut self) {
6515        self.cached_region.take();
6516        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6517        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6518            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6519            && self.diff_transforms.next_item().is_some()
6520        {
6521            self.diff_transforms.next();
6522        }
6523    }
6524
6525    fn next(&mut self) {
6526        self.cached_region.take();
6527        match self
6528            .diff_transforms
6529            .end()
6530            .excerpt_dimension
6531            .cmp(&self.excerpts.end())
6532        {
6533            cmp::Ordering::Less => self.diff_transforms.next(),
6534            cmp::Ordering::Greater => self.excerpts.next(),
6535            cmp::Ordering::Equal => {
6536                self.diff_transforms.next();
6537                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6538                    || self.diff_transforms.item().is_none()
6539                {
6540                    self.excerpts.next();
6541                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6542                    self.diff_transforms.item()
6543                    && self
6544                        .excerpts
6545                        .item()
6546                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6547                {
6548                    self.excerpts.next();
6549                }
6550            }
6551        }
6552    }
6553
6554    fn prev(&mut self) {
6555        self.cached_region.take();
6556        match self
6557            .diff_transforms
6558            .start()
6559            .excerpt_dimension
6560            .cmp(self.excerpts.start())
6561        {
6562            cmp::Ordering::Less => self.excerpts.prev(),
6563            cmp::Ordering::Greater => self.diff_transforms.prev(),
6564            cmp::Ordering::Equal => {
6565                self.diff_transforms.prev();
6566                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6567                    || self.diff_transforms.item().is_none()
6568                {
6569                    self.excerpts.prev();
6570                }
6571            }
6572        }
6573    }
6574
6575    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6576        if self.cached_region.is_none() {
6577            self.cached_region = self.build_region();
6578        }
6579        self.cached_region.clone()
6580    }
6581
6582    fn is_at_start_of_excerpt(&mut self) -> bool {
6583        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6584            return false;
6585        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6586            return true;
6587        }
6588
6589        self.diff_transforms.prev();
6590        let prev_transform = self.diff_transforms.item();
6591        self.diff_transforms.next();
6592
6593        prev_transform.is_none_or(|next_transform| {
6594            matches!(next_transform, DiffTransform::BufferContent { .. })
6595        })
6596    }
6597
6598    fn is_at_end_of_excerpt(&mut self) -> bool {
6599        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6600            return false;
6601        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6602            || self.diff_transforms.item().is_none()
6603        {
6604            return true;
6605        }
6606
6607        let next_transform = self.diff_transforms.next_item();
6608        next_transform.is_none_or(|next_transform| match next_transform {
6609            DiffTransform::BufferContent { .. } => true,
6610            DiffTransform::DeletedHunk { hunk_info, .. } => self
6611                .excerpts
6612                .item()
6613                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6614        })
6615    }
6616
6617    fn main_buffer_position(&self) -> Option<D> {
6618        let excerpt = self.excerpts.item()?;
6619        let buffer = &excerpt.buffer;
6620        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6621        let mut buffer_start = buffer_context_start;
6622        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6623        buffer_start.add_assign(&overshoot);
6624        Some(buffer_start)
6625    }
6626
6627    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6628        let excerpt = self.excerpts.item()?;
6629        match self.diff_transforms.item()? {
6630            DiffTransform::DeletedHunk {
6631                buffer_id,
6632                base_text_byte_range,
6633                has_trailing_newline,
6634                hunk_info,
6635                ..
6636            } => {
6637                let diff = self.diffs.get(buffer_id)?;
6638                let buffer = diff.base_text();
6639                let mut rope_cursor = buffer.as_rope().cursor(0);
6640                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6641                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6642                let mut buffer_end = buffer_start;
6643                buffer_end.add_assign(&buffer_range_len);
6644                let start = self.diff_transforms.start().output_dimension.0;
6645                let end = self.diff_transforms.end().output_dimension.0;
6646                Some(MultiBufferRegion {
6647                    buffer,
6648                    excerpt,
6649                    has_trailing_newline: *has_trailing_newline,
6650                    is_main_buffer: false,
6651                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6652                        hunk_info.hunk_secondary_status,
6653                    )),
6654                    buffer_range: buffer_start..buffer_end,
6655                    range: start..end,
6656                })
6657            }
6658            DiffTransform::BufferContent {
6659                inserted_hunk_info, ..
6660            } => {
6661                let buffer = &excerpt.buffer;
6662                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6663
6664                let mut start = self.diff_transforms.start().output_dimension.0;
6665                let mut buffer_start = buffer_context_start;
6666                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6667                    let overshoot =
6668                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6669                    start.add_assign(&overshoot);
6670                } else {
6671                    let overshoot =
6672                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6673                    buffer_start.add_assign(&overshoot);
6674                }
6675
6676                let mut end;
6677                let mut buffer_end;
6678                let has_trailing_newline;
6679                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6680                    let overshoot =
6681                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6682                    end = self.diff_transforms.end().output_dimension.0;
6683                    buffer_end = buffer_context_start;
6684                    buffer_end.add_assign(&overshoot);
6685                    has_trailing_newline = false;
6686                } else {
6687                    let overshoot =
6688                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6689                    end = self.diff_transforms.start().output_dimension.0;
6690                    end.add_assign(&overshoot);
6691                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6692                    has_trailing_newline = excerpt.has_trailing_newline;
6693                };
6694
6695                Some(MultiBufferRegion {
6696                    buffer,
6697                    excerpt,
6698                    has_trailing_newline,
6699                    is_main_buffer: true,
6700                    diff_hunk_status: inserted_hunk_info
6701                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6702                    buffer_range: buffer_start..buffer_end,
6703                    range: start..end,
6704                })
6705            }
6706        }
6707    }
6708
6709    fn excerpt(&self) -> Option<&'a Excerpt> {
6710        self.excerpts.item()
6711    }
6712}
6713
6714impl History {
6715    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6716        self.transaction_depth += 1;
6717        if self.transaction_depth == 1 {
6718            let id = self.next_transaction_id.tick();
6719            self.undo_stack.push(Transaction {
6720                id,
6721                buffer_transactions: Default::default(),
6722                first_edit_at: now,
6723                last_edit_at: now,
6724                suppress_grouping: false,
6725            });
6726            Some(id)
6727        } else {
6728            None
6729        }
6730    }
6731
6732    fn end_transaction(
6733        &mut self,
6734        now: Instant,
6735        buffer_transactions: HashMap<BufferId, TransactionId>,
6736    ) -> bool {
6737        assert_ne!(self.transaction_depth, 0);
6738        self.transaction_depth -= 1;
6739        if self.transaction_depth == 0 {
6740            if buffer_transactions.is_empty() {
6741                self.undo_stack.pop();
6742                false
6743            } else {
6744                self.redo_stack.clear();
6745                let transaction = self.undo_stack.last_mut().unwrap();
6746                transaction.last_edit_at = now;
6747                for (buffer_id, transaction_id) in buffer_transactions {
6748                    transaction
6749                        .buffer_transactions
6750                        .entry(buffer_id)
6751                        .or_insert(transaction_id);
6752                }
6753                true
6754            }
6755        } else {
6756            false
6757        }
6758    }
6759
6760    fn push_transaction<'a, T>(
6761        &mut self,
6762        buffer_transactions: T,
6763        now: Instant,
6764        cx: &Context<MultiBuffer>,
6765    ) where
6766        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6767    {
6768        assert_eq!(self.transaction_depth, 0);
6769        let transaction = Transaction {
6770            id: self.next_transaction_id.tick(),
6771            buffer_transactions: buffer_transactions
6772                .into_iter()
6773                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6774                .collect(),
6775            first_edit_at: now,
6776            last_edit_at: now,
6777            suppress_grouping: false,
6778        };
6779        if !transaction.buffer_transactions.is_empty() {
6780            self.undo_stack.push(transaction);
6781            self.redo_stack.clear();
6782        }
6783    }
6784
6785    fn finalize_last_transaction(&mut self) {
6786        if let Some(transaction) = self.undo_stack.last_mut() {
6787            transaction.suppress_grouping = true;
6788        }
6789    }
6790
6791    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6792        if let Some(ix) = self
6793            .undo_stack
6794            .iter()
6795            .rposition(|transaction| transaction.id == transaction_id)
6796        {
6797            Some(self.undo_stack.remove(ix))
6798        } else if let Some(ix) = self
6799            .redo_stack
6800            .iter()
6801            .rposition(|transaction| transaction.id == transaction_id)
6802        {
6803            Some(self.redo_stack.remove(ix))
6804        } else {
6805            None
6806        }
6807    }
6808
6809    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6810        self.undo_stack
6811            .iter()
6812            .find(|transaction| transaction.id == transaction_id)
6813            .or_else(|| {
6814                self.redo_stack
6815                    .iter()
6816                    .find(|transaction| transaction.id == transaction_id)
6817            })
6818    }
6819
6820    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6821        self.undo_stack
6822            .iter_mut()
6823            .find(|transaction| transaction.id == transaction_id)
6824            .or_else(|| {
6825                self.redo_stack
6826                    .iter_mut()
6827                    .find(|transaction| transaction.id == transaction_id)
6828            })
6829    }
6830
6831    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6832        assert_eq!(self.transaction_depth, 0);
6833        if let Some(transaction) = self.undo_stack.pop() {
6834            self.redo_stack.push(transaction);
6835            self.redo_stack.last_mut()
6836        } else {
6837            None
6838        }
6839    }
6840
6841    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6842        assert_eq!(self.transaction_depth, 0);
6843        if let Some(transaction) = self.redo_stack.pop() {
6844            self.undo_stack.push(transaction);
6845            self.undo_stack.last_mut()
6846        } else {
6847            None
6848        }
6849    }
6850
6851    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6852        let ix = self
6853            .undo_stack
6854            .iter()
6855            .rposition(|transaction| transaction.id == transaction_id)?;
6856        let transaction = self.undo_stack.remove(ix);
6857        self.redo_stack.push(transaction);
6858        self.redo_stack.last()
6859    }
6860
6861    fn group(&mut self) -> Option<TransactionId> {
6862        let mut count = 0;
6863        let mut transactions = self.undo_stack.iter();
6864        if let Some(mut transaction) = transactions.next_back() {
6865            while let Some(prev_transaction) = transactions.next_back() {
6866                if !prev_transaction.suppress_grouping
6867                    && transaction.first_edit_at - prev_transaction.last_edit_at
6868                        <= self.group_interval
6869                {
6870                    transaction = prev_transaction;
6871                    count += 1;
6872                } else {
6873                    break;
6874                }
6875            }
6876        }
6877        self.group_trailing(count)
6878    }
6879
6880    fn group_until(&mut self, transaction_id: TransactionId) {
6881        let mut count = 0;
6882        for transaction in self.undo_stack.iter().rev() {
6883            if transaction.id == transaction_id {
6884                self.group_trailing(count);
6885                break;
6886            } else if transaction.suppress_grouping {
6887                break;
6888            } else {
6889                count += 1;
6890            }
6891        }
6892    }
6893
6894    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6895        let new_len = self.undo_stack.len() - n;
6896        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6897        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6898            if let Some(transaction) = transactions_to_merge.last() {
6899                last_transaction.last_edit_at = transaction.last_edit_at;
6900            }
6901            for to_merge in transactions_to_merge {
6902                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6903                    last_transaction
6904                        .buffer_transactions
6905                        .entry(*buffer_id)
6906                        .or_insert(*transaction_id);
6907                }
6908            }
6909        }
6910
6911        self.undo_stack.truncate(new_len);
6912        self.undo_stack.last().map(|t| t.id)
6913    }
6914}
6915
6916impl Excerpt {
6917    fn new(
6918        id: ExcerptId,
6919        locator: Locator,
6920        buffer_id: BufferId,
6921        buffer: BufferSnapshot,
6922        range: ExcerptRange<text::Anchor>,
6923        has_trailing_newline: bool,
6924    ) -> Self {
6925        Excerpt {
6926            id,
6927            locator,
6928            max_buffer_row: range.context.end.to_point(&buffer).row,
6929            text_summary: buffer
6930                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6931            buffer_id,
6932            buffer,
6933            range,
6934            has_trailing_newline,
6935        }
6936    }
6937
6938    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6939        let content_start = self.range.context.start.to_offset(&self.buffer);
6940        let chunks_start = content_start + range.start;
6941        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6942
6943        let footer_height = if self.has_trailing_newline
6944            && range.start <= self.text_summary.len
6945            && range.end > self.text_summary.len
6946        {
6947            1
6948        } else {
6949            0
6950        };
6951
6952        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
6953
6954        ExcerptChunks {
6955            excerpt_id: self.id,
6956            content_chunks,
6957            footer_height,
6958        }
6959    }
6960
6961    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
6962        let content_start = self.range.context.start.to_offset(&self.buffer);
6963        let chunks_start = content_start + range.start;
6964        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6965        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
6966        excerpt_chunks.footer_height = if self.has_trailing_newline
6967            && range.start <= self.text_summary.len
6968            && range.end > self.text_summary.len
6969        {
6970            1
6971        } else {
6972            0
6973        };
6974    }
6975
6976    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
6977        if text_anchor
6978            .cmp(&self.range.context.start, &self.buffer)
6979            .is_lt()
6980        {
6981            self.range.context.start
6982        } else if text_anchor
6983            .cmp(&self.range.context.end, &self.buffer)
6984            .is_gt()
6985        {
6986            self.range.context.end
6987        } else {
6988            text_anchor
6989        }
6990    }
6991
6992    fn contains(&self, anchor: &Anchor) -> bool {
6993        (anchor.buffer_id == None || anchor.buffer_id == Some(self.buffer_id))
6994            && self
6995                .range
6996                .context
6997                .start
6998                .cmp(&anchor.text_anchor, &self.buffer)
6999                .is_le()
7000            && self
7001                .range
7002                .context
7003                .end
7004                .cmp(&anchor.text_anchor, &self.buffer)
7005                .is_ge()
7006    }
7007
7008    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7009    fn buffer_start_offset(&self) -> usize {
7010        self.range.context.start.to_offset(&self.buffer)
7011    }
7012
7013    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7014    fn buffer_end_offset(&self) -> usize {
7015        self.buffer_start_offset() + self.text_summary.len
7016    }
7017}
7018
7019impl<'a> MultiBufferExcerpt<'a> {
7020    pub fn id(&self) -> ExcerptId {
7021        self.excerpt.id
7022    }
7023
7024    pub fn buffer_id(&self) -> BufferId {
7025        self.excerpt.buffer_id
7026    }
7027
7028    pub fn start_anchor(&self) -> Anchor {
7029        Anchor::in_buffer(
7030            self.excerpt.id,
7031            self.excerpt.buffer_id,
7032            self.excerpt.range.context.start,
7033        )
7034    }
7035
7036    pub fn end_anchor(&self) -> Anchor {
7037        Anchor::in_buffer(
7038            self.excerpt.id,
7039            self.excerpt.buffer_id,
7040            self.excerpt.range.context.end,
7041        )
7042    }
7043
7044    pub fn buffer(&self) -> &'a BufferSnapshot {
7045        &self.excerpt.buffer
7046    }
7047
7048    pub fn buffer_range(&self) -> Range<usize> {
7049        self.buffer_offset
7050            ..self
7051                .excerpt
7052                .range
7053                .context
7054                .end
7055                .to_offset(&self.excerpt.buffer.text)
7056    }
7057
7058    pub fn start_offset(&self) -> usize {
7059        self.offset
7060    }
7061
7062    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7063    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7064        self.map_range_to_buffer(offset..offset).start
7065    }
7066
7067    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7068    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7069        self.diff_transforms
7070            .seek(&OutputDimension(range.start), Bias::Right);
7071        let start = self.map_offset_to_buffer_internal(range.start);
7072        let end = if range.end > range.start {
7073            self.diff_transforms
7074                .seek_forward(&OutputDimension(range.end), Bias::Right);
7075            self.map_offset_to_buffer_internal(range.end)
7076        } else {
7077            start
7078        };
7079        start..end
7080    }
7081
7082    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7083        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7084        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7085            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7086        };
7087        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7088        self.buffer_offset + offset_in_excerpt
7089    }
7090
7091    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7092    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7093        self.map_range_from_buffer(buffer_offset..buffer_offset)
7094            .start
7095    }
7096
7097    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7098    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7099        if buffer_range.start < self.buffer_offset {
7100            log::warn!(
7101                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7102            );
7103            return buffer_range;
7104        }
7105        let overshoot = buffer_range.start - self.buffer_offset;
7106        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7107        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7108        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7109            log::warn!(
7110                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7111            );
7112            return buffer_range;
7113        }
7114        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7115        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7116
7117        let end = if buffer_range.end > buffer_range.start {
7118            let overshoot = buffer_range.end - self.buffer_offset;
7119            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7120            self.diff_transforms
7121                .seek_forward(&excerpt_offset, Bias::Right);
7122            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7123            self.diff_transforms.start().output_dimension.0 + overshoot
7124        } else {
7125            start
7126        };
7127
7128        start..end
7129    }
7130
7131    /// Returns true if the entirety of the given range is in the buffer's excerpt
7132    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7133        range.start >= self.excerpt.buffer_start_offset()
7134            && range.end <= self.excerpt.buffer_end_offset()
7135    }
7136
7137    pub fn max_buffer_row(&self) -> u32 {
7138        self.excerpt.max_buffer_row
7139    }
7140}
7141
7142impl ExcerptId {
7143    pub fn min() -> Self {
7144        Self(0)
7145    }
7146
7147    pub fn max() -> Self {
7148        Self(u32::MAX)
7149    }
7150
7151    pub fn to_proto(self) -> u64 {
7152        self.0 as _
7153    }
7154
7155    pub fn from_proto(proto: u64) -> Self {
7156        Self(proto as _)
7157    }
7158
7159    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7160        let a = snapshot.excerpt_locator_for_id(*self);
7161        let b = snapshot.excerpt_locator_for_id(*other);
7162        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7163    }
7164}
7165
7166impl From<ExcerptId> for usize {
7167    fn from(val: ExcerptId) -> Self {
7168        val.0 as usize
7169    }
7170}
7171
7172impl fmt::Debug for Excerpt {
7173    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7174        f.debug_struct("Excerpt")
7175            .field("id", &self.id)
7176            .field("locator", &self.locator)
7177            .field("buffer_id", &self.buffer_id)
7178            .field("range", &self.range)
7179            .field("text_summary", &self.text_summary)
7180            .field("has_trailing_newline", &self.has_trailing_newline)
7181            .finish()
7182    }
7183}
7184
7185impl sum_tree::Item for Excerpt {
7186    type Summary = ExcerptSummary;
7187
7188    fn summary(&self, _cx: ()) -> Self::Summary {
7189        let mut text = self.text_summary;
7190        if self.has_trailing_newline {
7191            text += TextSummary::from("\n");
7192        }
7193        ExcerptSummary {
7194            excerpt_id: self.id,
7195            excerpt_locator: self.locator.clone(),
7196            widest_line_number: self.max_buffer_row,
7197            text,
7198        }
7199    }
7200}
7201
7202impl sum_tree::Item for ExcerptIdMapping {
7203    type Summary = ExcerptId;
7204
7205    fn summary(&self, _cx: ()) -> Self::Summary {
7206        self.id
7207    }
7208}
7209
7210impl sum_tree::KeyedItem for ExcerptIdMapping {
7211    type Key = ExcerptId;
7212
7213    fn key(&self) -> Self::Key {
7214        self.id
7215    }
7216}
7217
7218impl DiffTransform {
7219    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7220        match self {
7221            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7222            DiffTransform::BufferContent {
7223                inserted_hunk_info, ..
7224            } => *inserted_hunk_info,
7225        }
7226    }
7227}
7228
7229impl sum_tree::Item for DiffTransform {
7230    type Summary = DiffTransformSummary;
7231
7232    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7233        match self {
7234            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7235                input: *summary,
7236                output: *summary,
7237            },
7238            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7239                input: TextSummary::default(),
7240                output: *summary,
7241            },
7242        }
7243    }
7244}
7245
7246impl DiffTransformSummary {
7247    fn excerpt_len(&self) -> ExcerptOffset {
7248        ExcerptOffset::new(self.input.len)
7249    }
7250}
7251
7252impl sum_tree::ContextLessSummary for DiffTransformSummary {
7253    fn zero() -> Self {
7254        DiffTransformSummary {
7255            input: TextSummary::default(),
7256            output: TextSummary::default(),
7257        }
7258    }
7259
7260    fn add_summary(&mut self, other: &Self) {
7261        self.input += other.input;
7262        self.output += other.output;
7263    }
7264}
7265
7266impl sum_tree::ContextLessSummary for ExcerptId {
7267    fn zero() -> Self {
7268        Self(0)
7269    }
7270
7271    fn add_summary(&mut self, summary: &Self) {
7272        *self = cmp::max(*self, *summary);
7273    }
7274}
7275
7276impl sum_tree::ContextLessSummary for ExcerptSummary {
7277    fn zero() -> Self {
7278        Self::default()
7279    }
7280
7281    fn add_summary(&mut self, summary: &Self) {
7282        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7283        self.excerpt_locator = summary.excerpt_locator.clone();
7284        Summary::add_summary(&mut self.text, &summary.text, ());
7285        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7286    }
7287}
7288
7289impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7290    fn zero(_cx: ()) -> Self {
7291        Default::default()
7292    }
7293
7294    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7295        self.value += summary.text.len;
7296    }
7297}
7298
7299impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7300    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7301        Ord::cmp(&self.value, &cursor_location.text.len)
7302    }
7303}
7304
7305impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7306    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
7307        Ord::cmp(&Some(self), cursor_location)
7308    }
7309}
7310
7311impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7312    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7313        Ord::cmp(self, &cursor_location.excerpt_locator)
7314    }
7315}
7316
7317impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7318    fn zero(_cx: ()) -> Self {
7319        Default::default()
7320    }
7321
7322    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7323        self.value += summary.text.lines;
7324    }
7325}
7326
7327impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7328    for ExcerptDimension<D>
7329{
7330    fn zero(_: ()) -> Self {
7331        ExcerptDimension(D::default())
7332    }
7333
7334    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7335        self.0.add_assign(&D::from_text_summary(&summary.text))
7336    }
7337}
7338
7339impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7340    fn zero(_cx: ()) -> Self {
7341        Default::default()
7342    }
7343
7344    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7345        *self = Some(&summary.excerpt_locator);
7346    }
7347}
7348
7349impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7350    fn zero(_cx: ()) -> Self {
7351        Default::default()
7352    }
7353
7354    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7355        *self = Some(summary.excerpt_id);
7356    }
7357}
7358
7359#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7360struct ExcerptDimension<T>(T);
7361
7362#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7363struct OutputDimension<T>(T);
7364
7365impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7366    fn zero(_: ()) -> Self {
7367        ExcerptOffset::new(0)
7368    }
7369
7370    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7371        self.value += summary.input.len;
7372    }
7373}
7374
7375impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7376    fn zero(_: ()) -> Self {
7377        ExcerptPoint::new(0, 0)
7378    }
7379
7380    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7381        self.value += summary.input.lines;
7382    }
7383}
7384
7385impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7386    for ExcerptDimension<D>
7387{
7388    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
7389        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7390    }
7391}
7392
7393impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7394    for ExcerptDimension<D>
7395{
7396    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7397        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7398    }
7399}
7400
7401impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7402    fn zero(_: ()) -> Self {
7403        ExcerptDimension(D::default())
7404    }
7405
7406    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7407        self.0.add_assign(&D::from_text_summary(&summary.input))
7408    }
7409}
7410
7411impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7412    for OutputDimension<D>
7413{
7414    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7415        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7416    }
7417}
7418
7419impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7420    fn zero(_: ()) -> Self {
7421        OutputDimension(D::default())
7422    }
7423
7424    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7425        self.0.add_assign(&D::from_text_summary(&summary.output))
7426    }
7427}
7428
7429impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7430    fn zero(_: ()) -> Self {
7431        TextSummary::default()
7432    }
7433
7434    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7435        *self += summary.output
7436    }
7437}
7438
7439impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7440    fn zero(_: ()) -> Self {
7441        0
7442    }
7443
7444    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7445        *self += summary.output.len
7446    }
7447}
7448
7449impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7450    fn zero(_: ()) -> Self {
7451        Point::new(0, 0)
7452    }
7453
7454    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7455        *self += summary.output.lines
7456    }
7457}
7458
7459impl MultiBufferRows<'_> {
7460    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7461        self.point = Point::new(row, 0);
7462        self.cursor.seek(&self.point);
7463    }
7464}
7465
7466impl Iterator for MultiBufferRows<'_> {
7467    type Item = RowInfo;
7468
7469    fn next(&mut self) -> Option<Self::Item> {
7470        if self.is_empty && self.point.row == 0 {
7471            self.point += Point::new(1, 0);
7472            return Some(RowInfo {
7473                buffer_id: None,
7474                buffer_row: Some(0),
7475                multibuffer_row: Some(MultiBufferRow(0)),
7476                diff_status: None,
7477                expand_info: None,
7478            });
7479        }
7480
7481        let mut region = self.cursor.region()?;
7482        while self.point >= region.range.end {
7483            self.cursor.next();
7484            if let Some(next_region) = self.cursor.region() {
7485                region = next_region;
7486            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7487                let multibuffer_row = MultiBufferRow(self.point.row);
7488                let last_excerpt = self
7489                    .cursor
7490                    .excerpts
7491                    .item()
7492                    .or(self.cursor.excerpts.prev_item())?;
7493                let last_row = last_excerpt
7494                    .range
7495                    .context
7496                    .end
7497                    .to_point(&last_excerpt.buffer)
7498                    .row;
7499
7500                let first_row = last_excerpt
7501                    .range
7502                    .context
7503                    .start
7504                    .to_point(&last_excerpt.buffer)
7505                    .row;
7506
7507                let expand_info = if self.is_singleton {
7508                    None
7509                } else {
7510                    let needs_expand_up = first_row == last_row
7511                        && last_row > 0
7512                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7513                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
7514
7515                    if needs_expand_up && needs_expand_down {
7516                        Some(ExpandExcerptDirection::UpAndDown)
7517                    } else if needs_expand_up {
7518                        Some(ExpandExcerptDirection::Up)
7519                    } else if needs_expand_down {
7520                        Some(ExpandExcerptDirection::Down)
7521                    } else {
7522                        None
7523                    }
7524                    .map(|direction| ExpandInfo {
7525                        direction,
7526                        excerpt_id: last_excerpt.id,
7527                    })
7528                };
7529                self.point += Point::new(1, 0);
7530                return Some(RowInfo {
7531                    buffer_id: Some(last_excerpt.buffer_id),
7532                    buffer_row: Some(last_row),
7533                    multibuffer_row: Some(multibuffer_row),
7534                    diff_status: None,
7535                    expand_info,
7536                });
7537            } else {
7538                return None;
7539            };
7540        }
7541
7542        let overshoot = self.point - region.range.start;
7543        let buffer_point = region.buffer_range.start + overshoot;
7544        let expand_info = if self.is_singleton {
7545            None
7546        } else {
7547            let needs_expand_up = self.point.row == region.range.start.row
7548                && self.cursor.is_at_start_of_excerpt()
7549                && buffer_point.row > 0;
7550            let needs_expand_down = (region.excerpt.has_trailing_newline
7551                && self.point.row + 1 == region.range.end.row
7552                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7553                && self.cursor.is_at_end_of_excerpt()
7554                && buffer_point.row < region.buffer.max_point().row;
7555
7556            if needs_expand_up && needs_expand_down {
7557                Some(ExpandExcerptDirection::UpAndDown)
7558            } else if needs_expand_up {
7559                Some(ExpandExcerptDirection::Up)
7560            } else if needs_expand_down {
7561                Some(ExpandExcerptDirection::Down)
7562            } else {
7563                None
7564            }
7565            .map(|direction| ExpandInfo {
7566                direction,
7567                excerpt_id: region.excerpt.id,
7568            })
7569        };
7570
7571        let result = Some(RowInfo {
7572            buffer_id: Some(region.buffer.remote_id()),
7573            buffer_row: Some(buffer_point.row),
7574            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7575            diff_status: region
7576                .diff_hunk_status
7577                .filter(|_| self.point < region.range.end),
7578            expand_info,
7579        });
7580        self.point += Point::new(1, 0);
7581        result
7582    }
7583}
7584
7585impl<'a> MultiBufferChunks<'a> {
7586    pub fn offset(&self) -> usize {
7587        self.range.start
7588    }
7589
7590    pub fn seek(&mut self, range: Range<usize>) {
7591        self.diff_transforms.seek(&range.end, Bias::Right);
7592        let mut excerpt_end = self.diff_transforms.start().1;
7593        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7594            let overshoot = range.end - self.diff_transforms.start().0;
7595            excerpt_end.value += overshoot;
7596        }
7597
7598        self.diff_transforms.seek(&range.start, Bias::Right);
7599        let mut excerpt_start = self.diff_transforms.start().1;
7600        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7601            let overshoot = range.start - self.diff_transforms.start().0;
7602            excerpt_start.value += overshoot;
7603        }
7604
7605        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7606        self.buffer_chunk.take();
7607        self.range = range;
7608    }
7609
7610    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7611        self.excerpt_offset_range = new_range.clone();
7612        self.excerpts.seek(&new_range.start, Bias::Right);
7613        if let Some(excerpt) = self.excerpts.item() {
7614            let excerpt_start = *self.excerpts.start();
7615            if let Some(excerpt_chunks) = self
7616                .excerpt_chunks
7617                .as_mut()
7618                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7619            {
7620                excerpt.seek_chunks(
7621                    excerpt_chunks,
7622                    (self.excerpt_offset_range.start - excerpt_start).value
7623                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7624                );
7625            } else {
7626                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7627                    (self.excerpt_offset_range.start - excerpt_start).value
7628                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7629                    self.language_aware,
7630                ));
7631            }
7632        } else {
7633            self.excerpt_chunks = None;
7634        }
7635    }
7636
7637    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7638        loop {
7639            if self.excerpt_offset_range.is_empty() {
7640                return None;
7641            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7642                self.excerpt_offset_range.start.value += chunk.text.len();
7643                return Some(chunk);
7644            } else {
7645                self.excerpts.next();
7646                let excerpt = self.excerpts.item()?;
7647                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7648                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7649                    self.language_aware,
7650                ));
7651            }
7652        }
7653    }
7654}
7655
7656impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7657    type Item = &'a str;
7658
7659    fn next(&mut self) -> Option<Self::Item> {
7660        let mut region = self.cursor.region()?;
7661        if self.offset == region.range.start {
7662            self.cursor.prev();
7663            region = self.cursor.region()?;
7664            let start_overshoot = self.start.saturating_sub(region.range.start);
7665            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7666                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7667            ));
7668        }
7669
7670        if self.offset == region.range.end && region.has_trailing_newline {
7671            self.offset -= 1;
7672            Some("\n")
7673        } else {
7674            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7675            self.offset -= chunk.len();
7676            Some(chunk)
7677        }
7678    }
7679}
7680
7681impl<'a> Iterator for MultiBufferChunks<'a> {
7682    type Item = Chunk<'a>;
7683
7684    fn next(&mut self) -> Option<Chunk<'a>> {
7685        if self.range.start >= self.range.end {
7686            return None;
7687        }
7688        if self.range.start == self.diff_transforms.end().0 {
7689            self.diff_transforms.next();
7690        }
7691
7692        let diff_transform_start = self.diff_transforms.start().0;
7693        let diff_transform_end = self.diff_transforms.end().0;
7694        debug_assert!(self.range.start < diff_transform_end);
7695
7696        let diff_transform = self.diff_transforms.item()?;
7697        match diff_transform {
7698            DiffTransform::BufferContent { .. } => {
7699                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7700                    chunk
7701                } else {
7702                    let chunk = self.next_excerpt_chunk().unwrap();
7703                    self.buffer_chunk.insert(chunk)
7704                };
7705
7706                let chunk_end = self.range.start + chunk.text.len();
7707                let diff_transform_end = diff_transform_end.min(self.range.end);
7708
7709                if diff_transform_end < chunk_end {
7710                    let split_idx = diff_transform_end - self.range.start;
7711                    let (before, after) = chunk.text.split_at(split_idx);
7712                    self.range.start = diff_transform_end;
7713                    let mask = (1 << split_idx) - 1;
7714                    let chars = chunk.chars & mask;
7715                    let tabs = chunk.tabs & mask;
7716
7717                    chunk.text = after;
7718                    chunk.chars = chunk.chars >> split_idx;
7719                    chunk.tabs = chunk.tabs >> split_idx;
7720
7721                    Some(Chunk {
7722                        text: before,
7723                        chars,
7724                        tabs,
7725                        ..chunk.clone()
7726                    })
7727                } else {
7728                    self.range.start = chunk_end;
7729                    self.buffer_chunk.take()
7730                }
7731            }
7732            DiffTransform::DeletedHunk {
7733                buffer_id,
7734                base_text_byte_range,
7735                has_trailing_newline,
7736                ..
7737            } => {
7738                let base_text_start =
7739                    base_text_byte_range.start + self.range.start - diff_transform_start;
7740                let base_text_end =
7741                    base_text_byte_range.start + self.range.end - diff_transform_start;
7742                let base_text_end = base_text_end.min(base_text_byte_range.end);
7743
7744                let mut chunks = if let Some((_, mut chunks)) = self
7745                    .diff_base_chunks
7746                    .take()
7747                    .filter(|(id, _)| id == buffer_id)
7748                {
7749                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7750                    {
7751                        chunks.seek(base_text_start..base_text_end);
7752                    }
7753                    chunks
7754                } else {
7755                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7756                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7757                };
7758
7759                let chunk = if let Some(chunk) = chunks.next() {
7760                    self.range.start += chunk.text.len();
7761                    self.diff_base_chunks = Some((*buffer_id, chunks));
7762                    chunk
7763                } else {
7764                    debug_assert!(has_trailing_newline);
7765                    self.range.start += "\n".len();
7766                    Chunk {
7767                        text: "\n",
7768                        chars: 1u128,
7769                        ..Default::default()
7770                    }
7771                };
7772                Some(chunk)
7773            }
7774        }
7775    }
7776}
7777
7778impl MultiBufferBytes<'_> {
7779    fn consume(&mut self, len: usize) {
7780        self.range.start += len;
7781        self.chunk = &self.chunk[len..];
7782
7783        if !self.range.is_empty() && self.chunk.is_empty() {
7784            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7785                self.chunk = chunk;
7786            } else if self.has_trailing_newline {
7787                self.has_trailing_newline = false;
7788                self.chunk = b"\n";
7789            } else {
7790                self.cursor.next();
7791                if let Some(region) = self.cursor.region() {
7792                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7793                        region.buffer_range.start
7794                            ..(region.buffer_range.start + self.range.end - region.range.start)
7795                                .min(region.buffer_range.end),
7796                    );
7797                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7798                    self.excerpt_bytes = Some(excerpt_bytes);
7799                    self.has_trailing_newline =
7800                        region.has_trailing_newline && self.range.end >= region.range.end;
7801                    if self.chunk.is_empty() && self.has_trailing_newline {
7802                        self.has_trailing_newline = false;
7803                        self.chunk = b"\n";
7804                    }
7805                }
7806            }
7807        }
7808    }
7809}
7810
7811impl<'a> Iterator for MultiBufferBytes<'a> {
7812    type Item = &'a [u8];
7813
7814    fn next(&mut self) -> Option<Self::Item> {
7815        let chunk = self.chunk;
7816        if chunk.is_empty() {
7817            None
7818        } else {
7819            self.consume(chunk.len());
7820            Some(chunk)
7821        }
7822    }
7823}
7824
7825impl io::Read for MultiBufferBytes<'_> {
7826    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7827        let len = cmp::min(buf.len(), self.chunk.len());
7828        buf[..len].copy_from_slice(&self.chunk[..len]);
7829        if len > 0 {
7830            self.consume(len);
7831        }
7832        Ok(len)
7833    }
7834}
7835
7836impl io::Read for ReversedMultiBufferBytes<'_> {
7837    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7838        let len = cmp::min(buf.len(), self.chunk.len());
7839        buf[..len].copy_from_slice(&self.chunk[..len]);
7840        buf[..len].reverse();
7841        if len > 0 {
7842            self.range.end -= len;
7843            self.chunk = &self.chunk[..self.chunk.len() - len];
7844            if !self.range.is_empty()
7845                && self.chunk.is_empty()
7846                && let Some(chunk) = self.chunks.next()
7847            {
7848                self.chunk = chunk.as_bytes();
7849            }
7850        }
7851        Ok(len)
7852    }
7853}
7854
7855impl<'a> Iterator for ExcerptChunks<'a> {
7856    type Item = Chunk<'a>;
7857
7858    fn next(&mut self) -> Option<Self::Item> {
7859        if let Some(chunk) = self.content_chunks.next() {
7860            return Some(chunk);
7861        }
7862
7863        if self.footer_height > 0 {
7864            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7865            let chars = (1 << self.footer_height) - 1;
7866            self.footer_height = 0;
7867            return Some(Chunk {
7868                text,
7869                chars,
7870                ..Default::default()
7871            });
7872        }
7873
7874        None
7875    }
7876}
7877
7878impl ToOffset for Point {
7879    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7880        snapshot.point_to_offset(*self)
7881    }
7882}
7883
7884impl ToOffset for usize {
7885    #[track_caller]
7886    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7887        assert!(
7888            *self <= snapshot.len(),
7889            "offset {} is greater than the snapshot.len() {}",
7890            *self,
7891            snapshot.len(),
7892        );
7893        *self
7894    }
7895}
7896
7897impl ToOffset for OffsetUtf16 {
7898    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7899        snapshot.offset_utf16_to_offset(*self)
7900    }
7901}
7902
7903impl ToOffset for PointUtf16 {
7904    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7905        snapshot.point_utf16_to_offset(*self)
7906    }
7907}
7908
7909impl ToOffsetUtf16 for OffsetUtf16 {
7910    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7911        *self
7912    }
7913}
7914
7915impl ToOffsetUtf16 for usize {
7916    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7917        snapshot.offset_to_offset_utf16(*self)
7918    }
7919}
7920
7921impl ToPoint for usize {
7922    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7923        snapshot.offset_to_point(*self)
7924    }
7925}
7926
7927impl ToPoint for Point {
7928    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7929        *self
7930    }
7931}
7932
7933impl ToPointUtf16 for usize {
7934    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7935        snapshot.offset_to_point_utf16(*self)
7936    }
7937}
7938
7939impl ToPointUtf16 for Point {
7940    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7941        snapshot.point_to_point_utf16(*self)
7942    }
7943}
7944
7945impl ToPointUtf16 for PointUtf16 {
7946    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7947        *self
7948    }
7949}
7950
7951impl From<ExcerptId> for EntityId {
7952    fn from(id: ExcerptId) -> Self {
7953        EntityId::from(id.0 as u64)
7954    }
7955}
7956
7957#[cfg(debug_assertions)]
7958pub mod debug {
7959    use super::*;
7960
7961    pub trait ToMultiBufferDebugRanges {
7962        fn to_multi_buffer_debug_ranges(&self, snapshot: &MultiBufferSnapshot)
7963        -> Vec<Range<usize>>;
7964    }
7965
7966    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
7967        fn to_multi_buffer_debug_ranges(
7968            &self,
7969            snapshot: &MultiBufferSnapshot,
7970        ) -> Vec<Range<usize>> {
7971            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
7972        }
7973    }
7974
7975    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
7976        fn to_multi_buffer_debug_ranges(
7977            &self,
7978            snapshot: &MultiBufferSnapshot,
7979        ) -> Vec<Range<usize>> {
7980            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
7981                .to_multi_buffer_debug_ranges(snapshot)
7982        }
7983    }
7984
7985    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
7986        fn to_multi_buffer_debug_ranges(
7987            &self,
7988            snapshot: &MultiBufferSnapshot,
7989        ) -> Vec<Range<usize>> {
7990            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
7991        }
7992    }
7993
7994    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
7995        fn to_multi_buffer_debug_ranges(
7996            &self,
7997            snapshot: &MultiBufferSnapshot,
7998        ) -> Vec<Range<usize>> {
7999            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8000        }
8001    }
8002
8003    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8004        fn to_multi_buffer_debug_ranges(
8005            &self,
8006            snapshot: &MultiBufferSnapshot,
8007        ) -> Vec<Range<usize>> {
8008            self.iter()
8009                .map(|item| {
8010                    let offset = item.to_offset(snapshot);
8011                    offset..offset
8012                })
8013                .collect()
8014        }
8015    }
8016
8017    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8018        fn to_multi_buffer_debug_ranges(
8019            &self,
8020            snapshot: &MultiBufferSnapshot,
8021        ) -> Vec<Range<usize>> {
8022            self.iter()
8023                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8024                .collect()
8025        }
8026    }
8027}