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