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