multi_buffer.rs

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