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