1mod anchor;
   2#[cfg(test)]
   3mod multi_buffer_tests;
   4mod position;
   5
   6pub use anchor::{Anchor, AnchorRangeExt, Offset};
   7pub use position::{TypedOffset, TypedPoint, TypedRow};
   8
   9use anyhow::{Result, anyhow};
  10use buffer_diff::{
  11    BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffHunkSecondaryStatus, DiffHunkStatus,
  12    DiffHunkStatusKind,
  13};
  14use clock::ReplicaId;
  15use collections::{BTreeMap, Bound, HashMap, HashSet};
  16use gpui::{App, AppContext as _, Context, Entity, EntityId, EventEmitter, Task};
  17use itertools::Itertools;
  18use language::{
  19    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharClassifier,
  20    CharKind, CharScopeContext, Chunk, CursorShape, DiagnosticEntryRef, DiskState, File,
  21    IndentGuideSettings, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16, Outline,
  22    OutlineItem, Point, PointUtf16, Selection, TextDimension, TextObject, ToOffset as _,
  23    ToPoint as _, TransactionId, TreeSitterOptions, Unclipped,
  24    language_settings::{LanguageSettings, language_settings},
  25};
  26
  27use rope::DimensionPair;
  28use smallvec::SmallVec;
  29use smol::future::yield_now;
  30use std::{
  31    any::type_name,
  32    borrow::Cow,
  33    cell::{Cell, Ref, RefCell},
  34    cmp, fmt,
  35    future::Future,
  36    io,
  37    iter::{self, FromIterator},
  38    mem,
  39    ops::{Range, RangeBounds, Sub},
  40    rc::Rc,
  41    str,
  42    sync::Arc,
  43    time::{Duration, Instant},
  44};
  45use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, Summary, TreeMap};
  46use text::{
  47    BufferId, Edit, LineIndent, TextSummary,
  48    locator::Locator,
  49    subscription::{Subscription, Topic},
  50};
  51use theme::SyntaxTheme;
  52use util::post_inc;
  53
  54const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  55
  56#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  57pub struct ExcerptId(u32);
  58
  59/// One or more [`Buffers`](Buffer) being edited in a single view.
  60///
  61/// See <https://zed.dev/features#multi-buffers>
  62pub struct MultiBuffer {
  63    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  64    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  65    snapshot: RefCell<MultiBufferSnapshot>,
  66    /// Contains the state of the buffers being edited
  67    buffers: RefCell<HashMap<BufferId, BufferState>>,
  68    // only used by consumers using `set_excerpts_for_buffer`
  69    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  70    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  71    diffs: HashMap<BufferId, DiffState>,
  72    // all_diff_hunks_expanded: bool,
  73    subscriptions: Topic,
  74    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  75    singleton: bool,
  76    history: History,
  77    title: Option<String>,
  78    capability: Capability,
  79    buffer_changed_since_sync: Rc<Cell<bool>>,
  80}
  81
  82#[derive(Clone, Debug, PartialEq, Eq)]
  83pub enum Event {
  84    ExcerptsAdded {
  85        buffer: Entity<Buffer>,
  86        predecessor: ExcerptId,
  87        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  88    },
  89    ExcerptsRemoved {
  90        ids: Vec<ExcerptId>,
  91        removed_buffer_ids: Vec<BufferId>,
  92    },
  93    ExcerptsExpanded {
  94        ids: Vec<ExcerptId>,
  95    },
  96    ExcerptsEdited {
  97        excerpt_ids: Vec<ExcerptId>,
  98        buffer_ids: Vec<BufferId>,
  99    },
 100    DiffHunksToggled,
 101    Edited {
 102        singleton_buffer_edited: bool,
 103        edited_buffer: Option<Entity<Buffer>>,
 104    },
 105    TransactionUndone {
 106        transaction_id: TransactionId,
 107    },
 108    Reloaded,
 109    LanguageChanged(BufferId),
 110    Reparsed(BufferId),
 111    Saved,
 112    FileHandleChanged,
 113    DirtyChanged,
 114    DiagnosticsUpdated,
 115    BufferDiffChanged,
 116}
 117
 118/// A diff hunk, representing a range of consequent lines in a multibuffer.
 119#[derive(Debug, Clone, PartialEq, Eq)]
 120pub struct MultiBufferDiffHunk {
 121    /// The row range in the multibuffer where this diff hunk appears.
 122    pub row_range: Range<MultiBufferRow>,
 123    /// The buffer ID that this hunk belongs to.
 124    pub buffer_id: BufferId,
 125    /// The range of the underlying buffer that this hunk corresponds to.
 126    pub buffer_range: Range<text::Anchor>,
 127    /// The excerpt that contains the diff hunk.
 128    pub excerpt_id: ExcerptId,
 129    /// The range within the buffer's diff base that this hunk corresponds to.
 130    pub diff_base_byte_range: Range<usize>,
 131    /// Whether or not this hunk also appears in the 'secondary diff'.
 132    pub secondary_status: DiffHunkSecondaryStatus,
 133}
 134
 135impl MultiBufferDiffHunk {
 136    pub fn status(&self) -> DiffHunkStatus {
 137        let kind = if self.buffer_range.start == self.buffer_range.end {
 138            DiffHunkStatusKind::Deleted
 139        } else if self.diff_base_byte_range.is_empty() {
 140            DiffHunkStatusKind::Added
 141        } else {
 142            DiffHunkStatusKind::Modified
 143        };
 144        DiffHunkStatus {
 145            kind,
 146            secondary: self.secondary_status,
 147        }
 148    }
 149
 150    pub fn is_created_file(&self) -> bool {
 151        self.diff_base_byte_range == (0..0)
 152            && self.buffer_range == (text::Anchor::MIN..text::Anchor::MAX)
 153    }
 154
 155    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 156        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.start);
 157        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_id, self.buffer_range.end);
 158        start..end
 159    }
 160}
 161
 162#[derive(PartialEq, Eq, Ord, PartialOrd, Clone, Hash, Debug)]
 163pub struct PathKey {
 164    namespace: u32,
 165    path: Arc<str>,
 166}
 167
 168impl PathKey {
 169    pub fn namespaced(namespace: u32, path: Arc<str>) -> Self {
 170        Self { namespace, path }
 171    }
 172
 173    pub fn for_buffer(buffer: &Entity<Buffer>, cx: &App) -> Self {
 174        if let Some(file) = buffer.read(cx).file() {
 175            Self::namespaced(1, file.full_path(cx).to_string_lossy().into_owned().into())
 176        } else {
 177            Self::namespaced(0, buffer.entity_id().to_string().into())
 178        }
 179    }
 180
 181    pub fn path(&self) -> &Arc<str> {
 182        &self.path
 183    }
 184}
 185
 186pub type MultiBufferPoint = Point;
 187type ExcerptOffset = TypedOffset<Excerpt>;
 188type ExcerptPoint = TypedPoint<Excerpt>;
 189
 190#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 191#[serde(transparent)]
 192pub struct MultiBufferRow(pub u32);
 193
 194impl MultiBufferRow {
 195    pub const MIN: Self = Self(0);
 196    pub const MAX: Self = Self(u32::MAX);
 197}
 198
 199impl std::ops::Add<usize> for MultiBufferRow {
 200    type Output = Self;
 201
 202    fn add(self, rhs: usize) -> Self::Output {
 203        MultiBufferRow(self.0 + rhs as u32)
 204    }
 205}
 206
 207#[derive(Clone)]
 208struct History {
 209    next_transaction_id: TransactionId,
 210    undo_stack: Vec<Transaction>,
 211    redo_stack: Vec<Transaction>,
 212    transaction_depth: usize,
 213    group_interval: Duration,
 214}
 215
 216#[derive(Clone)]
 217struct Transaction {
 218    id: TransactionId,
 219    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 220    first_edit_at: Instant,
 221    last_edit_at: Instant,
 222    suppress_grouping: bool,
 223}
 224
 225pub trait ToOffset: 'static + fmt::Debug {
 226    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 227}
 228
 229pub trait ToOffsetUtf16: 'static + fmt::Debug {
 230    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 231}
 232
 233pub trait ToPoint: 'static + fmt::Debug {
 234    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 235}
 236
 237pub trait ToPointUtf16: 'static + fmt::Debug {
 238    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 239}
 240
 241struct BufferState {
 242    buffer: Entity<Buffer>,
 243    last_version: clock::Global,
 244    last_non_text_state_update_count: usize,
 245    excerpts: Vec<Locator>,
 246    _subscriptions: [gpui::Subscription; 2],
 247}
 248
 249struct DiffState {
 250    diff: Entity<BufferDiff>,
 251    _subscription: gpui::Subscription,
 252}
 253
 254impl DiffState {
 255    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 256        DiffState {
 257            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 258                BufferDiffEvent::DiffChanged { changed_range } => {
 259                    if let Some(changed_range) = changed_range.clone() {
 260                        this.buffer_diff_changed(diff, changed_range, cx)
 261                    }
 262                    cx.emit(Event::BufferDiffChanged);
 263                }
 264                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 265                _ => {}
 266            }),
 267            diff,
 268        }
 269    }
 270}
 271
 272/// The contents of a [`MultiBuffer`] at a single point in time.
 273#[derive(Clone, Default)]
 274pub struct MultiBufferSnapshot {
 275    singleton: bool,
 276    excerpts: SumTree<Excerpt>,
 277    excerpt_ids: SumTree<ExcerptIdMapping>,
 278    diffs: TreeMap<BufferId, BufferDiffSnapshot>,
 279    diff_transforms: SumTree<DiffTransform>,
 280    replaced_excerpts: TreeMap<ExcerptId, ExcerptId>,
 281    trailing_excerpt_update_count: usize,
 282    all_diff_hunks_expanded: bool,
 283    non_text_state_update_count: usize,
 284    edit_count: usize,
 285    is_dirty: bool,
 286    has_deleted_file: bool,
 287    has_conflict: bool,
 288    show_headers: bool,
 289}
 290
 291#[derive(Debug, Clone)]
 292enum DiffTransform {
 293    BufferContent {
 294        summary: TextSummary,
 295        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 296    },
 297    DeletedHunk {
 298        summary: TextSummary,
 299        buffer_id: BufferId,
 300        hunk_info: DiffTransformHunkInfo,
 301        base_text_byte_range: Range<usize>,
 302        has_trailing_newline: bool,
 303    },
 304}
 305
 306#[derive(Clone, Copy, Debug)]
 307struct DiffTransformHunkInfo {
 308    excerpt_id: ExcerptId,
 309    hunk_start_anchor: text::Anchor,
 310    hunk_secondary_status: DiffHunkSecondaryStatus,
 311}
 312
 313impl Eq for DiffTransformHunkInfo {}
 314
 315impl PartialEq for DiffTransformHunkInfo {
 316    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 317        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 318    }
 319}
 320
 321impl std::hash::Hash for DiffTransformHunkInfo {
 322    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 323        self.excerpt_id.hash(state);
 324        self.hunk_start_anchor.hash(state);
 325    }
 326}
 327
 328#[derive(Clone)]
 329pub struct ExcerptInfo {
 330    pub id: ExcerptId,
 331    pub buffer: BufferSnapshot,
 332    pub buffer_id: BufferId,
 333    pub range: ExcerptRange<text::Anchor>,
 334    pub end_row: MultiBufferRow,
 335}
 336
 337impl std::fmt::Debug for ExcerptInfo {
 338    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 339        f.debug_struct(type_name::<Self>())
 340            .field("id", &self.id)
 341            .field("buffer_id", &self.buffer_id)
 342            .field("path", &self.buffer.file().map(|f| f.path()))
 343            .field("range", &self.range)
 344            .finish()
 345    }
 346}
 347
 348/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 349#[derive(Debug)]
 350pub struct ExcerptBoundary {
 351    pub prev: Option<ExcerptInfo>,
 352    pub next: ExcerptInfo,
 353    /// The row in the `MultiBuffer` where the boundary is located
 354    pub row: MultiBufferRow,
 355}
 356
 357impl ExcerptBoundary {
 358    pub fn starts_new_buffer(&self) -> bool {
 359        match (self.prev.as_ref(), &self.next) {
 360            (None, _) => true,
 361            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 362        }
 363    }
 364}
 365
 366#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 367pub struct ExpandInfo {
 368    pub direction: ExpandExcerptDirection,
 369    pub excerpt_id: ExcerptId,
 370}
 371
 372#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 373pub struct RowInfo {
 374    pub buffer_id: Option<BufferId>,
 375    pub buffer_row: Option<u32>,
 376    pub multibuffer_row: Option<MultiBufferRow>,
 377    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 378    pub expand_info: Option<ExpandInfo>,
 379}
 380
 381/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 382#[derive(Clone)]
 383struct Excerpt {
 384    /// The unique identifier for this excerpt
 385    id: ExcerptId,
 386    /// The location of the excerpt in the [`MultiBuffer`]
 387    locator: Locator,
 388    /// The buffer being excerpted
 389    buffer_id: BufferId,
 390    /// A snapshot of the buffer being excerpted
 391    buffer: BufferSnapshot,
 392    /// The range of the buffer to be shown in the excerpt
 393    range: ExcerptRange<text::Anchor>,
 394    /// The last row in the excerpted slice of the buffer
 395    max_buffer_row: BufferRow,
 396    /// A summary of the text in the excerpt
 397    text_summary: TextSummary,
 398    has_trailing_newline: bool,
 399}
 400
 401/// A public view into an `Excerpt` in a [`MultiBuffer`].
 402///
 403/// Contains methods for getting the [`Buffer`] of the excerpt,
 404/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 405#[derive(Clone)]
 406pub struct MultiBufferExcerpt<'a> {
 407    excerpt: &'a Excerpt,
 408    diff_transforms: sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<usize>>,
 409    offset: usize,
 410    excerpt_offset: ExcerptDimension<usize>,
 411    buffer_offset: usize,
 412}
 413
 414#[derive(Clone, Debug)]
 415struct ExcerptIdMapping {
 416    id: ExcerptId,
 417    locator: Locator,
 418}
 419
 420/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 421/// These ranges are relative to the buffer itself
 422#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 423pub struct ExcerptRange<T> {
 424    /// The full range of text to be shown in the excerpt.
 425    pub context: Range<T>,
 426    /// The primary range of text to be highlighted in the excerpt.
 427    /// In a multi-buffer search, this would be the text that matched the search
 428    pub primary: Range<T>,
 429}
 430
 431impl<T: Clone> ExcerptRange<T> {
 432    pub fn new(context: Range<T>) -> Self {
 433        Self {
 434            context: context.clone(),
 435            primary: context,
 436        }
 437    }
 438}
 439
 440#[derive(Clone, Debug, Default)]
 441pub struct ExcerptSummary {
 442    excerpt_id: ExcerptId,
 443    /// The location of the last [`Excerpt`] being summarized
 444    excerpt_locator: Locator,
 445    widest_line_number: u32,
 446    text: TextSummary,
 447}
 448
 449#[derive(Debug, Clone)]
 450pub struct DiffTransformSummary {
 451    input: TextSummary,
 452    output: TextSummary,
 453}
 454
 455#[derive(Clone)]
 456pub struct MultiBufferRows<'a> {
 457    point: Point,
 458    is_empty: bool,
 459    is_singleton: bool,
 460    cursor: MultiBufferCursor<'a, Point>,
 461}
 462
 463pub struct MultiBufferChunks<'a> {
 464    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 465    diff_transforms: Cursor<'a, 'static, DiffTransform, Dimensions<usize, ExcerptOffset>>,
 466    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 467    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 468    buffer_chunk: Option<Chunk<'a>>,
 469    range: Range<usize>,
 470    excerpt_offset_range: Range<ExcerptOffset>,
 471    excerpt_chunks: Option<ExcerptChunks<'a>>,
 472    language_aware: bool,
 473}
 474
 475pub struct ReversedMultiBufferChunks<'a> {
 476    cursor: MultiBufferCursor<'a, usize>,
 477    current_chunks: Option<rope::Chunks<'a>>,
 478    start: usize,
 479    offset: usize,
 480}
 481
 482pub struct MultiBufferBytes<'a> {
 483    range: Range<usize>,
 484    cursor: MultiBufferCursor<'a, usize>,
 485    excerpt_bytes: Option<text::Bytes<'a>>,
 486    has_trailing_newline: bool,
 487    chunk: &'a [u8],
 488}
 489
 490pub struct ReversedMultiBufferBytes<'a> {
 491    range: Range<usize>,
 492    chunks: ReversedMultiBufferChunks<'a>,
 493    chunk: &'a [u8],
 494}
 495
 496#[derive(Clone)]
 497struct DiffTransforms<D> {
 498    output_dimension: OutputDimension<D>,
 499    excerpt_dimension: ExcerptDimension<D>,
 500}
 501
 502impl<'a, D: TextDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<D> {
 503    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
 504        Self {
 505            output_dimension: OutputDimension::zero(cx),
 506            excerpt_dimension: <ExcerptDimension<D> as Dimension<'a, DiffTransformSummary>>::zero(
 507                cx,
 508            ),
 509        }
 510    }
 511
 512    fn add_summary(
 513        &mut self,
 514        summary: &'a DiffTransformSummary,
 515        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
 516    ) {
 517        self.output_dimension.add_summary(summary, cx);
 518        self.excerpt_dimension.add_summary(summary, cx);
 519    }
 520}
 521
 522#[derive(Clone)]
 523struct MultiBufferCursor<'a, D: TextDimension> {
 524    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<D>>,
 525    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<D>>,
 526    diffs: &'a TreeMap<BufferId, BufferDiffSnapshot>,
 527    cached_region: Option<MultiBufferRegion<'a, D>>,
 528}
 529
 530#[derive(Clone)]
 531struct MultiBufferRegion<'a, D: TextDimension> {
 532    buffer: &'a BufferSnapshot,
 533    is_main_buffer: bool,
 534    diff_hunk_status: Option<DiffHunkStatus>,
 535    excerpt: &'a Excerpt,
 536    buffer_range: Range<D>,
 537    range: Range<D>,
 538    has_trailing_newline: bool,
 539}
 540
 541struct ExcerptChunks<'a> {
 542    excerpt_id: ExcerptId,
 543    content_chunks: BufferChunks<'a>,
 544    footer_height: usize,
 545}
 546
 547#[derive(Debug)]
 548struct BufferEdit {
 549    range: Range<usize>,
 550    new_text: Arc<str>,
 551    is_insertion: bool,
 552    original_indent_column: Option<u32>,
 553    excerpt_id: ExcerptId,
 554}
 555
 556#[derive(Clone, Copy, Debug, PartialEq)]
 557enum DiffChangeKind {
 558    BufferEdited,
 559    DiffUpdated { base_changed: bool },
 560    ExpandOrCollapseHunks { expand: bool },
 561}
 562
 563#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 564pub enum ExpandExcerptDirection {
 565    Up,
 566    Down,
 567    UpAndDown,
 568}
 569
 570impl ExpandExcerptDirection {
 571    pub fn should_expand_up(&self) -> bool {
 572        match self {
 573            ExpandExcerptDirection::Up => true,
 574            ExpandExcerptDirection::Down => false,
 575            ExpandExcerptDirection::UpAndDown => true,
 576        }
 577    }
 578
 579    pub fn should_expand_down(&self) -> bool {
 580        match self {
 581            ExpandExcerptDirection::Up => false,
 582            ExpandExcerptDirection::Down => true,
 583            ExpandExcerptDirection::UpAndDown => true,
 584        }
 585    }
 586}
 587
 588#[derive(Clone, Debug, PartialEq)]
 589pub struct IndentGuide {
 590    pub buffer_id: BufferId,
 591    pub start_row: MultiBufferRow,
 592    pub end_row: MultiBufferRow,
 593    pub depth: u32,
 594    pub tab_size: u32,
 595    pub settings: IndentGuideSettings,
 596}
 597
 598impl IndentGuide {
 599    pub fn indent_level(&self) -> u32 {
 600        self.depth * self.tab_size
 601    }
 602}
 603
 604impl MultiBuffer {
 605    pub fn new(capability: Capability) -> Self {
 606        Self {
 607            snapshot: RefCell::new(MultiBufferSnapshot {
 608                show_headers: true,
 609                ..MultiBufferSnapshot::default()
 610            }),
 611            buffers: RefCell::default(),
 612            diffs: HashMap::default(),
 613            subscriptions: Topic::default(),
 614            singleton: false,
 615            capability,
 616            title: None,
 617            excerpts_by_path: Default::default(),
 618            paths_by_excerpt: Default::default(),
 619            buffer_changed_since_sync: Default::default(),
 620            history: History {
 621                next_transaction_id: clock::Lamport::default(),
 622                undo_stack: Vec::new(),
 623                redo_stack: Vec::new(),
 624                transaction_depth: 0,
 625                group_interval: Duration::from_millis(300),
 626            },
 627        }
 628    }
 629
 630    pub fn without_headers(capability: Capability) -> Self {
 631        Self {
 632            snapshot: Default::default(),
 633            buffers: Default::default(),
 634            excerpts_by_path: Default::default(),
 635            paths_by_excerpt: Default::default(),
 636            diffs: HashMap::default(),
 637            subscriptions: Default::default(),
 638            singleton: false,
 639            capability,
 640            buffer_changed_since_sync: Default::default(),
 641            history: History {
 642                next_transaction_id: Default::default(),
 643                undo_stack: Default::default(),
 644                redo_stack: Default::default(),
 645                transaction_depth: 0,
 646                group_interval: Duration::from_millis(300),
 647            },
 648            title: Default::default(),
 649        }
 650    }
 651
 652    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
 653        let mut buffers = HashMap::default();
 654        let buffer_changed_since_sync = Rc::new(Cell::new(false));
 655        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 656            buffer_state.buffer.update(new_cx, |buffer, _| {
 657                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
 658            });
 659            buffers.insert(
 660                *buffer_id,
 661                BufferState {
 662                    buffer: buffer_state.buffer.clone(),
 663                    last_version: buffer_state.last_version.clone(),
 664                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 665                    excerpts: buffer_state.excerpts.clone(),
 666                    _subscriptions: [
 667                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 668                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 669                    ],
 670                },
 671            );
 672        }
 673        let mut diff_bases = HashMap::default();
 674        for (buffer_id, diff) in self.diffs.iter() {
 675            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
 676        }
 677        Self {
 678            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 679            buffers: RefCell::new(buffers),
 680            excerpts_by_path: Default::default(),
 681            paths_by_excerpt: Default::default(),
 682            diffs: diff_bases,
 683            subscriptions: Default::default(),
 684            singleton: self.singleton,
 685            capability: self.capability,
 686            history: self.history.clone(),
 687            title: self.title.clone(),
 688            buffer_changed_since_sync,
 689        }
 690    }
 691
 692    pub fn with_title(mut self, title: String) -> Self {
 693        self.title = Some(title);
 694        self
 695    }
 696
 697    pub fn read_only(&self) -> bool {
 698        self.capability == Capability::ReadOnly
 699    }
 700
 701    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
 702        let mut this = Self::new(buffer.read(cx).capability());
 703        this.singleton = true;
 704        this.push_excerpts(
 705            buffer,
 706            [ExcerptRange::new(text::Anchor::MIN..text::Anchor::MAX)],
 707            cx,
 708        );
 709        this.snapshot.borrow_mut().singleton = true;
 710        this
 711    }
 712
 713    /// Returns an up-to-date snapshot of the MultiBuffer.
 714    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
 715        self.sync(cx);
 716        self.snapshot.borrow().clone()
 717    }
 718
 719    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
 720        self.sync(cx);
 721        self.snapshot.borrow()
 722    }
 723
 724    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
 725        if self.singleton {
 726            Some(
 727                self.buffers
 728                    .borrow()
 729                    .values()
 730                    .next()
 731                    .unwrap()
 732                    .buffer
 733                    .clone(),
 734            )
 735        } else {
 736            None
 737        }
 738    }
 739
 740    pub fn is_singleton(&self) -> bool {
 741        self.singleton
 742    }
 743
 744    pub fn subscribe(&mut self) -> Subscription {
 745        self.subscriptions.subscribe()
 746    }
 747
 748    pub fn is_dirty(&self, cx: &App) -> bool {
 749        self.read(cx).is_dirty()
 750    }
 751
 752    pub fn has_deleted_file(&self, cx: &App) -> bool {
 753        self.read(cx).has_deleted_file()
 754    }
 755
 756    pub fn has_conflict(&self, cx: &App) -> bool {
 757        self.read(cx).has_conflict()
 758    }
 759
 760    // The `is_empty` signature doesn't match what clippy expects
 761    #[allow(clippy::len_without_is_empty)]
 762    pub fn len(&self, cx: &App) -> usize {
 763        self.read(cx).len()
 764    }
 765
 766    pub fn is_empty(&self) -> bool {
 767        self.buffers.borrow().is_empty()
 768    }
 769
 770    pub fn symbols_containing<T: ToOffset>(
 771        &self,
 772        offset: T,
 773        theme: Option<&SyntaxTheme>,
 774        cx: &App,
 775    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 776        self.read(cx).symbols_containing(offset, theme)
 777    }
 778
 779    pub fn edit<I, S, T>(
 780        &self,
 781        edits: I,
 782        autoindent_mode: Option<AutoindentMode>,
 783        cx: &mut Context<Self>,
 784    ) where
 785        I: IntoIterator<Item = (Range<S>, T)>,
 786        S: ToOffset,
 787        T: Into<Arc<str>>,
 788    {
 789        let snapshot = self.read(cx);
 790        let edits = edits
 791            .into_iter()
 792            .map(|(range, new_text)| {
 793                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 794                if range.start > range.end {
 795                    mem::swap(&mut range.start, &mut range.end);
 796                }
 797                (range, new_text.into())
 798            })
 799            .collect::<Vec<_>>();
 800
 801        return edit_internal(self, snapshot, edits, autoindent_mode, cx);
 802
 803        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 804        fn edit_internal(
 805            this: &MultiBuffer,
 806            snapshot: Ref<MultiBufferSnapshot>,
 807            edits: Vec<(Range<usize>, Arc<str>)>,
 808            mut autoindent_mode: Option<AutoindentMode>,
 809            cx: &mut Context<MultiBuffer>,
 810        ) {
 811            if this.read_only() || this.buffers.borrow().is_empty() {
 812                return;
 813            }
 814
 815            let original_indent_columns = match &mut autoindent_mode {
 816                Some(AutoindentMode::Block {
 817                    original_indent_columns,
 818                }) => mem::take(original_indent_columns),
 819                _ => Default::default(),
 820            };
 821
 822            let (buffer_edits, edited_excerpt_ids) =
 823                this.convert_edits_to_buffer_edits(edits, &snapshot, &original_indent_columns);
 824            drop(snapshot);
 825
 826            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
 827            for (buffer_id, mut edits) in buffer_edits {
 828                buffer_ids.push(buffer_id);
 829                edits.sort_by_key(|edit| edit.range.start);
 830                this.buffers.borrow()[&buffer_id]
 831                    .buffer
 832                    .update(cx, |buffer, cx| {
 833                        let mut edits = edits.into_iter().peekable();
 834                        let mut insertions = Vec::new();
 835                        let mut original_indent_columns = Vec::new();
 836                        let mut deletions = Vec::new();
 837                        let empty_str: Arc<str> = Arc::default();
 838                        while let Some(BufferEdit {
 839                            mut range,
 840                            mut new_text,
 841                            mut is_insertion,
 842                            original_indent_column,
 843                            excerpt_id,
 844                        }) = edits.next()
 845                        {
 846                            while let Some(BufferEdit {
 847                                range: next_range,
 848                                is_insertion: next_is_insertion,
 849                                new_text: next_new_text,
 850                                excerpt_id: next_excerpt_id,
 851                                ..
 852                            }) = edits.peek()
 853                            {
 854                                if range.end >= next_range.start {
 855                                    range.end = cmp::max(next_range.end, range.end);
 856                                    is_insertion |= *next_is_insertion;
 857                                    if excerpt_id == *next_excerpt_id {
 858                                        new_text = format!("{new_text}{next_new_text}").into();
 859                                    }
 860                                    edits.next();
 861                                } else {
 862                                    break;
 863                                }
 864                            }
 865
 866                            if is_insertion {
 867                                original_indent_columns.push(original_indent_column);
 868                                insertions.push((
 869                                    buffer.anchor_before(range.start)
 870                                        ..buffer.anchor_before(range.end),
 871                                    new_text.clone(),
 872                                ));
 873                            } else if !range.is_empty() {
 874                                deletions.push((
 875                                    buffer.anchor_before(range.start)
 876                                        ..buffer.anchor_before(range.end),
 877                                    empty_str.clone(),
 878                                ));
 879                            }
 880                        }
 881
 882                        let deletion_autoindent_mode =
 883                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 884                                Some(AutoindentMode::Block {
 885                                    original_indent_columns: Default::default(),
 886                                })
 887                            } else {
 888                                autoindent_mode.clone()
 889                            };
 890                        let insertion_autoindent_mode =
 891                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 892                                Some(AutoindentMode::Block {
 893                                    original_indent_columns,
 894                                })
 895                            } else {
 896                                autoindent_mode.clone()
 897                            };
 898
 899                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 900                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 901                    })
 902            }
 903
 904            cx.emit(Event::ExcerptsEdited {
 905                excerpt_ids: edited_excerpt_ids,
 906                buffer_ids,
 907            });
 908        }
 909    }
 910
 911    fn convert_edits_to_buffer_edits(
 912        &self,
 913        edits: Vec<(Range<usize>, Arc<str>)>,
 914        snapshot: &MultiBufferSnapshot,
 915        original_indent_columns: &[Option<u32>],
 916    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
 917        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 918        let mut edited_excerpt_ids = Vec::new();
 919        let mut cursor = snapshot.cursor::<usize>();
 920        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
 921            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
 922
 923            cursor.seek(&range.start);
 924            let mut start_region = cursor.region().expect("start offset out of bounds");
 925            if !start_region.is_main_buffer {
 926                cursor.next();
 927                if let Some(region) = cursor.region() {
 928                    start_region = region;
 929                } else {
 930                    continue;
 931                }
 932            }
 933
 934            if range.end < start_region.range.start {
 935                continue;
 936            }
 937
 938            if range.end > start_region.range.end {
 939                cursor.seek_forward(&range.end);
 940            }
 941            let mut end_region = cursor.region().expect("end offset out of bounds");
 942            if !end_region.is_main_buffer {
 943                cursor.prev();
 944                if let Some(region) = cursor.region() {
 945                    end_region = region;
 946                } else {
 947                    continue;
 948                }
 949            }
 950
 951            if range.start > end_region.range.end {
 952                continue;
 953            }
 954
 955            let start_overshoot = range.start.saturating_sub(start_region.range.start);
 956            let end_overshoot = range.end.saturating_sub(end_region.range.start);
 957            let buffer_start = (start_region.buffer_range.start + start_overshoot)
 958                .min(start_region.buffer_range.end);
 959            let buffer_end =
 960                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
 961
 962            if start_region.excerpt.id == end_region.excerpt.id {
 963                if start_region.is_main_buffer {
 964                    edited_excerpt_ids.push(start_region.excerpt.id);
 965                    buffer_edits
 966                        .entry(start_region.buffer.remote_id())
 967                        .or_default()
 968                        .push(BufferEdit {
 969                            range: buffer_start..buffer_end,
 970                            new_text,
 971                            is_insertion: true,
 972                            original_indent_column,
 973                            excerpt_id: start_region.excerpt.id,
 974                        });
 975                }
 976            } else {
 977                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
 978                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
 979                if start_region.is_main_buffer {
 980                    edited_excerpt_ids.push(start_region.excerpt.id);
 981                    buffer_edits
 982                        .entry(start_region.buffer.remote_id())
 983                        .or_default()
 984                        .push(BufferEdit {
 985                            range: start_excerpt_range,
 986                            new_text: new_text.clone(),
 987                            is_insertion: true,
 988                            original_indent_column,
 989                            excerpt_id: start_region.excerpt.id,
 990                        });
 991                }
 992                if end_region.is_main_buffer {
 993                    edited_excerpt_ids.push(end_region.excerpt.id);
 994                    buffer_edits
 995                        .entry(end_region.buffer.remote_id())
 996                        .or_default()
 997                        .push(BufferEdit {
 998                            range: end_excerpt_range,
 999                            new_text: new_text.clone(),
1000                            is_insertion: false,
1001                            original_indent_column,
1002                            excerpt_id: end_region.excerpt.id,
1003                        });
1004                }
1005
1006                cursor.seek(&range.start);
1007                cursor.next_excerpt();
1008                while let Some(region) = cursor.region() {
1009                    if region.excerpt.id == end_region.excerpt.id {
1010                        break;
1011                    }
1012                    if region.is_main_buffer {
1013                        edited_excerpt_ids.push(region.excerpt.id);
1014                        buffer_edits
1015                            .entry(region.buffer.remote_id())
1016                            .or_default()
1017                            .push(BufferEdit {
1018                                range: region.buffer_range,
1019                                new_text: new_text.clone(),
1020                                is_insertion: false,
1021                                original_indent_column,
1022                                excerpt_id: region.excerpt.id,
1023                            });
1024                    }
1025                    cursor.next_excerpt();
1026                }
1027            }
1028        }
1029        (buffer_edits, edited_excerpt_ids)
1030    }
1031
1032    pub fn autoindent_ranges<I, S>(&self, ranges: I, cx: &mut Context<Self>)
1033    where
1034        I: IntoIterator<Item = Range<S>>,
1035        S: ToOffset,
1036    {
1037        let snapshot = self.read(cx);
1038        let empty = Arc::<str>::from("");
1039        let edits = ranges
1040            .into_iter()
1041            .map(|range| {
1042                let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
1043                if range.start > range.end {
1044                    mem::swap(&mut range.start, &mut range.end);
1045                }
1046                (range, empty.clone())
1047            })
1048            .collect::<Vec<_>>();
1049
1050        return autoindent_ranges_internal(self, snapshot, edits, cx);
1051
1052        fn autoindent_ranges_internal(
1053            this: &MultiBuffer,
1054            snapshot: Ref<MultiBufferSnapshot>,
1055            edits: Vec<(Range<usize>, Arc<str>)>,
1056            cx: &mut Context<MultiBuffer>,
1057        ) {
1058            if this.read_only() || this.buffers.borrow().is_empty() {
1059                return;
1060            }
1061
1062            let (buffer_edits, edited_excerpt_ids) =
1063                this.convert_edits_to_buffer_edits(edits, &snapshot, &[]);
1064            drop(snapshot);
1065
1066            let mut buffer_ids = Vec::new();
1067            for (buffer_id, mut edits) in buffer_edits {
1068                buffer_ids.push(buffer_id);
1069                edits.sort_unstable_by_key(|edit| edit.range.start);
1070
1071                let mut ranges: Vec<Range<usize>> = Vec::new();
1072                for edit in edits {
1073                    if let Some(last_range) = ranges.last_mut()
1074                        && edit.range.start <= last_range.end
1075                    {
1076                        last_range.end = last_range.end.max(edit.range.end);
1077                        continue;
1078                    }
1079                    ranges.push(edit.range);
1080                }
1081
1082                this.buffers.borrow()[&buffer_id]
1083                    .buffer
1084                    .update(cx, |buffer, cx| {
1085                        buffer.autoindent_ranges(ranges, cx);
1086                    })
1087            }
1088
1089            cx.emit(Event::ExcerptsEdited {
1090                excerpt_ids: edited_excerpt_ids,
1091                buffer_ids,
1092            });
1093        }
1094    }
1095
1096    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
1097    // You can also request the insertion of empty lines above and below the line starting at the returned point.
1098    // Panics if the given position is invalid.
1099    pub fn insert_empty_line(
1100        &mut self,
1101        position: impl ToPoint,
1102        space_above: bool,
1103        space_below: bool,
1104        cx: &mut Context<Self>,
1105    ) -> Point {
1106        let multibuffer_point = position.to_point(&self.read(cx));
1107        let (buffer, buffer_point, _) = self.point_to_buffer_point(multibuffer_point, cx).unwrap();
1108        self.start_transaction(cx);
1109        let empty_line_start = buffer.update(cx, |buffer, cx| {
1110            buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
1111        });
1112        self.end_transaction(cx);
1113        multibuffer_point + (empty_line_start - buffer_point)
1114    }
1115
1116    pub fn start_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1117        self.start_transaction_at(Instant::now(), cx)
1118    }
1119
1120    pub fn start_transaction_at(
1121        &mut self,
1122        now: Instant,
1123        cx: &mut Context<Self>,
1124    ) -> Option<TransactionId> {
1125        if let Some(buffer) = self.as_singleton() {
1126            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1127        }
1128
1129        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1130            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
1131        }
1132        self.history.start_transaction(now)
1133    }
1134
1135    pub fn last_transaction_id(&self, cx: &App) -> Option<TransactionId> {
1136        if let Some(buffer) = self.as_singleton() {
1137            buffer
1138                .read(cx)
1139                .peek_undo_stack()
1140                .map(|history_entry| history_entry.transaction_id())
1141        } else {
1142            let last_transaction = self.history.undo_stack.last()?;
1143            Some(last_transaction.id)
1144        }
1145    }
1146
1147    pub fn end_transaction(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1148        self.end_transaction_at(Instant::now(), cx)
1149    }
1150
1151    pub fn end_transaction_at(
1152        &mut self,
1153        now: Instant,
1154        cx: &mut Context<Self>,
1155    ) -> Option<TransactionId> {
1156        if let Some(buffer) = self.as_singleton() {
1157            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
1158        }
1159
1160        let mut buffer_transactions = HashMap::default();
1161        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1162            if let Some(transaction_id) =
1163                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
1164            {
1165                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
1166            }
1167        }
1168
1169        if self.history.end_transaction(now, buffer_transactions) {
1170            let transaction_id = self.history.group().unwrap();
1171            Some(transaction_id)
1172        } else {
1173            None
1174        }
1175    }
1176
1177    pub fn edited_ranges_for_transaction<D>(
1178        &self,
1179        transaction_id: TransactionId,
1180        cx: &App,
1181    ) -> Vec<Range<D>>
1182    where
1183        D: TextDimension + Ord + Sub<D, Output = D>,
1184    {
1185        let Some(transaction) = self.history.transaction(transaction_id) else {
1186            return Vec::new();
1187        };
1188
1189        let mut ranges = Vec::new();
1190        let snapshot = self.read(cx);
1191        let buffers = self.buffers.borrow();
1192        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(());
1193
1194        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
1195            let Some(buffer_state) = buffers.get(buffer_id) else {
1196                continue;
1197            };
1198
1199            let buffer = buffer_state.buffer.read(cx);
1200            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
1201                for excerpt_id in &buffer_state.excerpts {
1202                    cursor.seek(excerpt_id, Bias::Left);
1203                    if let Some(excerpt) = cursor.item()
1204                        && excerpt.locator == *excerpt_id
1205                    {
1206                        let excerpt_buffer_start = excerpt.range.context.start.summary::<D>(buffer);
1207                        let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
1208                        let excerpt_range = excerpt_buffer_start..excerpt_buffer_end;
1209                        if excerpt_range.contains(&range.start)
1210                            && excerpt_range.contains(&range.end)
1211                        {
1212                            let excerpt_start = D::from_text_summary(&cursor.start().text);
1213
1214                            let mut start = excerpt_start;
1215                            start.add_assign(&(range.start - excerpt_buffer_start));
1216                            let mut end = excerpt_start;
1217                            end.add_assign(&(range.end - excerpt_buffer_start));
1218
1219                            ranges.push(start..end);
1220                            break;
1221                        }
1222                    }
1223                }
1224            }
1225        }
1226
1227        ranges.sort_by_key(|range| range.start);
1228        ranges
1229    }
1230
1231    pub fn merge_transactions(
1232        &mut self,
1233        transaction: TransactionId,
1234        destination: TransactionId,
1235        cx: &mut Context<Self>,
1236    ) {
1237        if let Some(buffer) = self.as_singleton() {
1238            buffer.update(cx, |buffer, _| {
1239                buffer.merge_transactions(transaction, destination)
1240            });
1241        } else if let Some(transaction) = self.history.forget(transaction)
1242            && let Some(destination) = self.history.transaction_mut(destination)
1243        {
1244            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1245                if let Some(destination_buffer_transaction_id) =
1246                    destination.buffer_transactions.get(&buffer_id)
1247                {
1248                    if let Some(state) = self.buffers.borrow().get(&buffer_id) {
1249                        state.buffer.update(cx, |buffer, _| {
1250                            buffer.merge_transactions(
1251                                buffer_transaction_id,
1252                                *destination_buffer_transaction_id,
1253                            )
1254                        });
1255                    }
1256                } else {
1257                    destination
1258                        .buffer_transactions
1259                        .insert(buffer_id, buffer_transaction_id);
1260                }
1261            }
1262        }
1263    }
1264
1265    pub fn finalize_last_transaction(&mut self, cx: &mut Context<Self>) {
1266        self.history.finalize_last_transaction();
1267        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1268            buffer.update(cx, |buffer, _| {
1269                buffer.finalize_last_transaction();
1270            });
1271        }
1272    }
1273
1274    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &Context<Self>)
1275    where
1276        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
1277    {
1278        self.history
1279            .push_transaction(buffer_transactions, Instant::now(), cx);
1280        self.history.finalize_last_transaction();
1281    }
1282
1283    pub fn group_until_transaction(
1284        &mut self,
1285        transaction_id: TransactionId,
1286        cx: &mut Context<Self>,
1287    ) {
1288        if let Some(buffer) = self.as_singleton() {
1289            buffer.update(cx, |buffer, _| {
1290                buffer.group_until_transaction(transaction_id)
1291            });
1292        } else {
1293            self.history.group_until(transaction_id);
1294        }
1295    }
1296
1297    pub fn set_active_selections(
1298        &self,
1299        selections: &[Selection<Anchor>],
1300        line_mode: bool,
1301        cursor_shape: CursorShape,
1302        cx: &mut Context<Self>,
1303    ) {
1304        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1305            Default::default();
1306        let snapshot = self.read(cx);
1307        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1308        for selection in selections {
1309            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1310            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1311
1312            cursor.seek(&Some(start_locator), Bias::Left);
1313            while let Some(excerpt) = cursor.item() {
1314                if excerpt.locator > *end_locator {
1315                    break;
1316                }
1317
1318                let mut start = excerpt.range.context.start;
1319                let mut end = excerpt.range.context.end;
1320                if excerpt.id == selection.start.excerpt_id {
1321                    start = selection.start.text_anchor;
1322                }
1323                if excerpt.id == selection.end.excerpt_id {
1324                    end = selection.end.text_anchor;
1325                }
1326                selections_by_buffer
1327                    .entry(excerpt.buffer_id)
1328                    .or_default()
1329                    .push(Selection {
1330                        id: selection.id,
1331                        start,
1332                        end,
1333                        reversed: selection.reversed,
1334                        goal: selection.goal,
1335                    });
1336
1337                cursor.next();
1338            }
1339        }
1340
1341        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1342            if !selections_by_buffer.contains_key(buffer_id) {
1343                buffer_state
1344                    .buffer
1345                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1346            }
1347        }
1348
1349        for (buffer_id, mut selections) in selections_by_buffer {
1350            self.buffers.borrow()[&buffer_id]
1351                .buffer
1352                .update(cx, |buffer, cx| {
1353                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1354                    let mut selections = selections.into_iter().peekable();
1355                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1356                        let mut selection = selections.next()?;
1357                        while let Some(next_selection) = selections.peek() {
1358                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1359                                let next_selection = selections.next().unwrap();
1360                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1361                                    selection.end = next_selection.end;
1362                                }
1363                            } else {
1364                                break;
1365                            }
1366                        }
1367                        Some(selection)
1368                    }));
1369                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1370                });
1371        }
1372    }
1373
1374    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1375        for buffer in self.buffers.borrow().values() {
1376            buffer
1377                .buffer
1378                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1379        }
1380    }
1381
1382    pub fn undo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1383        let mut transaction_id = None;
1384        if let Some(buffer) = self.as_singleton() {
1385            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1386        } else {
1387            while let Some(transaction) = self.history.pop_undo() {
1388                let mut undone = false;
1389                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1390                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1391                        undone |= buffer.update(cx, |buffer, cx| {
1392                            let undo_to = *buffer_transaction_id;
1393                            if let Some(entry) = buffer.peek_undo_stack() {
1394                                *buffer_transaction_id = entry.transaction_id();
1395                            }
1396                            buffer.undo_to_transaction(undo_to, cx)
1397                        });
1398                    }
1399                }
1400
1401                if undone {
1402                    transaction_id = Some(transaction.id);
1403                    break;
1404                }
1405            }
1406        }
1407
1408        if let Some(transaction_id) = transaction_id {
1409            cx.emit(Event::TransactionUndone { transaction_id });
1410        }
1411
1412        transaction_id
1413    }
1414
1415    pub fn redo(&mut self, cx: &mut Context<Self>) -> Option<TransactionId> {
1416        if let Some(buffer) = self.as_singleton() {
1417            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1418        }
1419
1420        while let Some(transaction) = self.history.pop_redo() {
1421            let mut redone = false;
1422            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1423                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1424                    redone |= buffer.update(cx, |buffer, cx| {
1425                        let redo_to = *buffer_transaction_id;
1426                        if let Some(entry) = buffer.peek_redo_stack() {
1427                            *buffer_transaction_id = entry.transaction_id();
1428                        }
1429                        buffer.redo_to_transaction(redo_to, cx)
1430                    });
1431                }
1432            }
1433
1434            if redone {
1435                return Some(transaction.id);
1436            }
1437        }
1438
1439        None
1440    }
1441
1442    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1443        if let Some(buffer) = self.as_singleton() {
1444            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1445        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1446            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1447                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1448                    buffer.update(cx, |buffer, cx| {
1449                        buffer.undo_transaction(*transaction_id, cx)
1450                    });
1451                }
1452            }
1453        }
1454    }
1455
1456    pub fn forget_transaction(&mut self, transaction_id: TransactionId, cx: &mut Context<Self>) {
1457        if let Some(buffer) = self.as_singleton() {
1458            buffer.update(cx, |buffer, _| {
1459                buffer.forget_transaction(transaction_id);
1460            });
1461        } else if let Some(transaction) = self.history.forget(transaction_id) {
1462            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1463                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1464                    state.buffer.update(cx, |buffer, _| {
1465                        buffer.forget_transaction(buffer_transaction_id);
1466                    });
1467                }
1468            }
1469        }
1470    }
1471
1472    pub fn push_excerpts<O>(
1473        &mut self,
1474        buffer: Entity<Buffer>,
1475        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1476        cx: &mut Context<Self>,
1477    ) -> Vec<ExcerptId>
1478    where
1479        O: text::ToOffset,
1480    {
1481        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1482    }
1483
1484    pub fn location_for_path(&self, path: &PathKey, cx: &App) -> Option<Anchor> {
1485        let excerpt_id = self.excerpts_by_path.get(path)?.first()?;
1486        let snapshot = self.snapshot(cx);
1487        let excerpt = snapshot.excerpt(*excerpt_id)?;
1488        Some(Anchor::in_buffer(
1489            *excerpt_id,
1490            excerpt.buffer_id,
1491            excerpt.range.context.start,
1492        ))
1493    }
1494
1495    pub fn excerpt_paths(&self) -> impl Iterator<Item = &PathKey> {
1496        self.excerpts_by_path.keys()
1497    }
1498
1499    fn expand_excerpts_with_paths(
1500        &mut self,
1501        ids: impl IntoIterator<Item = ExcerptId>,
1502        line_count: u32,
1503        direction: ExpandExcerptDirection,
1504        cx: &mut Context<Self>,
1505    ) {
1506        let grouped = ids
1507            .into_iter()
1508            .chunk_by(|id| self.paths_by_excerpt.get(id).cloned())
1509            .into_iter()
1510            .flat_map(|(k, v)| Some((k?, v.into_iter().collect::<Vec<_>>())))
1511            .collect::<Vec<_>>();
1512        let snapshot = self.snapshot(cx);
1513
1514        for (path, ids) in grouped.into_iter() {
1515            let Some(excerpt_ids) = self.excerpts_by_path.get(&path) else {
1516                continue;
1517            };
1518
1519            let ids_to_expand = HashSet::from_iter(ids);
1520            let expanded_ranges = excerpt_ids.iter().filter_map(|excerpt_id| {
1521                let excerpt = snapshot.excerpt(*excerpt_id)?;
1522
1523                let mut context = excerpt.range.context.to_point(&excerpt.buffer);
1524                if ids_to_expand.contains(excerpt_id) {
1525                    match direction {
1526                        ExpandExcerptDirection::Up => {
1527                            context.start.row = context.start.row.saturating_sub(line_count);
1528                            context.start.column = 0;
1529                        }
1530                        ExpandExcerptDirection::Down => {
1531                            context.end.row =
1532                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1533                            context.end.column = excerpt.buffer.line_len(context.end.row);
1534                        }
1535                        ExpandExcerptDirection::UpAndDown => {
1536                            context.start.row = context.start.row.saturating_sub(line_count);
1537                            context.start.column = 0;
1538                            context.end.row =
1539                                (context.end.row + line_count).min(excerpt.buffer.max_point().row);
1540                            context.end.column = excerpt.buffer.line_len(context.end.row);
1541                        }
1542                    }
1543                }
1544
1545                Some(ExcerptRange {
1546                    context,
1547                    primary: excerpt.range.primary.to_point(&excerpt.buffer),
1548                })
1549            });
1550            let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1551            for range in expanded_ranges {
1552                if let Some(last_range) = merged_ranges.last_mut()
1553                    && last_range.context.end >= range.context.start
1554                {
1555                    last_range.context.end = range.context.end;
1556                    continue;
1557                }
1558                merged_ranges.push(range)
1559            }
1560            let Some(excerpt_id) = excerpt_ids.first() else {
1561                continue;
1562            };
1563            let Some(buffer_id) = &snapshot.buffer_id_for_excerpt(*excerpt_id) else {
1564                continue;
1565            };
1566
1567            let Some(buffer) = self
1568                .buffers
1569                .borrow()
1570                .get(buffer_id)
1571                .map(|b| b.buffer.clone())
1572            else {
1573                continue;
1574            };
1575
1576            let buffer_snapshot = buffer.read(cx).snapshot();
1577            self.update_path_excerpts(path.clone(), buffer, &buffer_snapshot, merged_ranges, cx);
1578        }
1579    }
1580
1581    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1582    pub fn set_excerpts_for_path(
1583        &mut self,
1584        path: PathKey,
1585        buffer: Entity<Buffer>,
1586        ranges: impl IntoIterator<Item = Range<Point>>,
1587        context_line_count: u32,
1588        cx: &mut Context<Self>,
1589    ) -> (Vec<Range<Anchor>>, bool) {
1590        let buffer_snapshot = buffer.read(cx).snapshot();
1591        let excerpt_ranges = build_excerpt_ranges(ranges, context_line_count, &buffer_snapshot);
1592
1593        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1594        self.set_merged_excerpt_ranges_for_path(
1595            path,
1596            buffer,
1597            excerpt_ranges,
1598            &buffer_snapshot,
1599            new,
1600            counts,
1601            cx,
1602        )
1603    }
1604
1605    pub fn set_excerpt_ranges_for_path(
1606        &mut self,
1607        path: PathKey,
1608        buffer: Entity<Buffer>,
1609        buffer_snapshot: &BufferSnapshot,
1610        excerpt_ranges: Vec<ExcerptRange<Point>>,
1611        cx: &mut Context<Self>,
1612    ) -> (Vec<Range<Anchor>>, bool) {
1613        let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1614        self.set_merged_excerpt_ranges_for_path(
1615            path,
1616            buffer,
1617            excerpt_ranges,
1618            buffer_snapshot,
1619            new,
1620            counts,
1621            cx,
1622        )
1623    }
1624
1625    pub fn set_anchored_excerpts_for_path(
1626        &self,
1627        buffer: Entity<Buffer>,
1628        ranges: Vec<Range<text::Anchor>>,
1629        context_line_count: u32,
1630        cx: &mut Context<Self>,
1631    ) -> Task<Vec<Range<Anchor>>> {
1632        let buffer_snapshot = buffer.read(cx).snapshot();
1633        let path_key = PathKey::for_buffer(&buffer, cx);
1634        cx.spawn(async move |multi_buffer, cx| {
1635            let snapshot = buffer_snapshot.clone();
1636            let (excerpt_ranges, new, counts) = cx
1637                .background_spawn(async move {
1638                    let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
1639                    let excerpt_ranges =
1640                        build_excerpt_ranges(ranges, context_line_count, &snapshot);
1641                    let (new, counts) = Self::merge_excerpt_ranges(&excerpt_ranges);
1642                    (excerpt_ranges, new, counts)
1643                })
1644                .await;
1645
1646            multi_buffer
1647                .update(cx, move |multi_buffer, cx| {
1648                    let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
1649                        path_key,
1650                        buffer,
1651                        excerpt_ranges,
1652                        &buffer_snapshot,
1653                        new,
1654                        counts,
1655                        cx,
1656                    );
1657                    ranges
1658                })
1659                .ok()
1660                .unwrap_or_default()
1661        })
1662    }
1663
1664    /// Sets excerpts, returns `true` if at least one new excerpt was added.
1665    fn set_merged_excerpt_ranges_for_path(
1666        &mut self,
1667        path: PathKey,
1668        buffer: Entity<Buffer>,
1669        ranges: Vec<ExcerptRange<Point>>,
1670        buffer_snapshot: &BufferSnapshot,
1671        new: Vec<ExcerptRange<Point>>,
1672        counts: Vec<usize>,
1673        cx: &mut Context<Self>,
1674    ) -> (Vec<Range<Anchor>>, bool) {
1675        let (excerpt_ids, added_a_new_excerpt) =
1676            self.update_path_excerpts(path, buffer, buffer_snapshot, new, cx);
1677
1678        let mut result = Vec::new();
1679        let mut ranges = ranges.into_iter();
1680        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(counts.into_iter()) {
1681            for range in ranges.by_ref().take(range_count) {
1682                let range = Anchor::range_in_buffer(
1683                    excerpt_id,
1684                    buffer_snapshot.remote_id(),
1685                    buffer_snapshot.anchor_before(&range.primary.start)
1686                        ..buffer_snapshot.anchor_after(&range.primary.end),
1687                );
1688                result.push(range)
1689            }
1690        }
1691        (result, added_a_new_excerpt)
1692    }
1693
1694    fn merge_excerpt_ranges<'a>(
1695        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1696    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1697        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1698        let mut counts: Vec<usize> = Vec::new();
1699        for range in expanded_ranges {
1700            if let Some(last_range) = merged_ranges.last_mut() {
1701                debug_assert!(
1702                    last_range.context.start <= range.context.start,
1703                    "Last range: {last_range:?} Range: {range:?}"
1704                );
1705                if last_range.context.end >= range.context.start
1706                    || last_range.context.end.row + 1 == range.context.start.row
1707                {
1708                    last_range.context.end = range.context.end.max(last_range.context.end);
1709                    *counts.last_mut().unwrap() += 1;
1710                    continue;
1711                }
1712            }
1713            merged_ranges.push(range.clone());
1714            counts.push(1);
1715        }
1716        (merged_ranges, counts)
1717    }
1718
1719    fn update_path_excerpts(
1720        &mut self,
1721        path: PathKey,
1722        buffer: Entity<Buffer>,
1723        buffer_snapshot: &BufferSnapshot,
1724        new: Vec<ExcerptRange<Point>>,
1725        cx: &mut Context<Self>,
1726    ) -> (Vec<ExcerptId>, bool) {
1727        let mut insert_after = self
1728            .excerpts_by_path
1729            .range(..path.clone())
1730            .next_back()
1731            .map(|(_, value)| *value.last().unwrap())
1732            .unwrap_or(ExcerptId::min());
1733
1734        let existing = self
1735            .excerpts_by_path
1736            .get(&path)
1737            .cloned()
1738            .unwrap_or_default();
1739
1740        let mut new_iter = new.into_iter().peekable();
1741        let mut existing_iter = existing.into_iter().peekable();
1742
1743        let mut excerpt_ids = Vec::new();
1744        let mut to_remove = Vec::new();
1745        let mut to_insert: Vec<(ExcerptId, ExcerptRange<Point>)> = Vec::new();
1746        let mut added_a_new_excerpt = false;
1747        let snapshot = self.snapshot(cx);
1748
1749        let mut next_excerpt_id =
1750            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1751                last_entry.id.0 + 1
1752            } else {
1753                1
1754            };
1755
1756        let mut next_excerpt_id = move || ExcerptId(post_inc(&mut next_excerpt_id));
1757
1758        let mut excerpts_cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1759        excerpts_cursor.next();
1760
1761        loop {
1762            let new = new_iter.peek();
1763            let existing = if let Some(existing_id) = existing_iter.peek() {
1764                let locator = snapshot.excerpt_locator_for_id(*existing_id);
1765                excerpts_cursor.seek_forward(&Some(locator), Bias::Left);
1766                if let Some(excerpt) = excerpts_cursor.item() {
1767                    if excerpt.buffer_id != buffer_snapshot.remote_id() {
1768                        to_remove.push(*existing_id);
1769                        existing_iter.next();
1770                        continue;
1771                    }
1772                    Some((
1773                        *existing_id,
1774                        excerpt.range.context.to_point(buffer_snapshot),
1775                    ))
1776                } else {
1777                    None
1778                }
1779            } else {
1780                None
1781            };
1782
1783            if let Some((last_id, last)) = to_insert.last_mut() {
1784                if let Some(new) = new
1785                    && last.context.end >= new.context.start
1786                {
1787                    last.context.end = last.context.end.max(new.context.end);
1788                    excerpt_ids.push(*last_id);
1789                    new_iter.next();
1790                    continue;
1791                }
1792                if let Some((existing_id, existing_range)) = &existing
1793                    && last.context.end >= existing_range.start
1794                {
1795                    last.context.end = last.context.end.max(existing_range.end);
1796                    to_remove.push(*existing_id);
1797                    self.snapshot
1798                        .borrow_mut()
1799                        .replaced_excerpts
1800                        .insert(*existing_id, *last_id);
1801                    existing_iter.next();
1802                    continue;
1803                }
1804            }
1805
1806            match (new, existing) {
1807                (None, None) => break,
1808                (None, Some((existing_id, _))) => {
1809                    existing_iter.next();
1810                    to_remove.push(existing_id);
1811                    continue;
1812                }
1813                (Some(_), None) => {
1814                    added_a_new_excerpt = true;
1815                    let new_id = next_excerpt_id();
1816                    excerpt_ids.push(new_id);
1817                    to_insert.push((new_id, new_iter.next().unwrap()));
1818                    continue;
1819                }
1820                (Some(new), Some((_, existing_range))) => {
1821                    if existing_range.end < new.context.start {
1822                        let existing_id = existing_iter.next().unwrap();
1823                        to_remove.push(existing_id);
1824                        continue;
1825                    } else if existing_range.start > new.context.end {
1826                        let new_id = next_excerpt_id();
1827                        excerpt_ids.push(new_id);
1828                        to_insert.push((new_id, new_iter.next().unwrap()));
1829                        continue;
1830                    }
1831
1832                    if existing_range.start == new.context.start
1833                        && existing_range.end == new.context.end
1834                    {
1835                        self.insert_excerpts_with_ids_after(
1836                            insert_after,
1837                            buffer.clone(),
1838                            mem::take(&mut to_insert),
1839                            cx,
1840                        );
1841                        insert_after = existing_iter.next().unwrap();
1842                        excerpt_ids.push(insert_after);
1843                        new_iter.next();
1844                    } else {
1845                        let existing_id = existing_iter.next().unwrap();
1846                        let new_id = next_excerpt_id();
1847                        self.snapshot
1848                            .borrow_mut()
1849                            .replaced_excerpts
1850                            .insert(existing_id, new_id);
1851                        to_remove.push(existing_id);
1852                        let mut range = new_iter.next().unwrap();
1853                        range.context.start = range.context.start.min(existing_range.start);
1854                        range.context.end = range.context.end.max(existing_range.end);
1855                        excerpt_ids.push(new_id);
1856                        to_insert.push((new_id, range));
1857                    }
1858                }
1859            };
1860        }
1861
1862        self.insert_excerpts_with_ids_after(insert_after, buffer, to_insert, cx);
1863        self.remove_excerpts(to_remove, cx);
1864        if excerpt_ids.is_empty() {
1865            self.excerpts_by_path.remove(&path);
1866        } else {
1867            for excerpt_id in &excerpt_ids {
1868                self.paths_by_excerpt.insert(*excerpt_id, path.clone());
1869            }
1870            self.excerpts_by_path
1871                .insert(path, excerpt_ids.iter().dedup().cloned().collect());
1872        }
1873
1874        (excerpt_ids, added_a_new_excerpt)
1875    }
1876
1877    pub fn paths(&self) -> impl Iterator<Item = PathKey> + '_ {
1878        self.excerpts_by_path.keys().cloned()
1879    }
1880
1881    pub fn remove_excerpts_for_path(&mut self, path: PathKey, cx: &mut Context<Self>) {
1882        if let Some(to_remove) = self.excerpts_by_path.remove(&path) {
1883            self.remove_excerpts(to_remove, cx)
1884        }
1885    }
1886
1887    pub fn insert_excerpts_after<O>(
1888        &mut self,
1889        prev_excerpt_id: ExcerptId,
1890        buffer: Entity<Buffer>,
1891        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1892        cx: &mut Context<Self>,
1893    ) -> Vec<ExcerptId>
1894    where
1895        O: text::ToOffset,
1896    {
1897        let mut ids = Vec::new();
1898        let mut next_excerpt_id =
1899            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1900                last_entry.id.0 + 1
1901            } else {
1902                1
1903            };
1904        self.insert_excerpts_with_ids_after(
1905            prev_excerpt_id,
1906            buffer,
1907            ranges.into_iter().map(|range| {
1908                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1909                ids.push(id);
1910                (id, range)
1911            }),
1912            cx,
1913        );
1914        ids
1915    }
1916
1917    pub fn insert_excerpts_with_ids_after<O>(
1918        &mut self,
1919        prev_excerpt_id: ExcerptId,
1920        buffer: Entity<Buffer>,
1921        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1922        cx: &mut Context<Self>,
1923    ) where
1924        O: text::ToOffset,
1925    {
1926        assert_eq!(self.history.transaction_depth, 0);
1927        let mut ranges = ranges.into_iter().peekable();
1928        if ranges.peek().is_none() {
1929            return Default::default();
1930        }
1931
1932        self.sync(cx);
1933
1934        let buffer_snapshot = buffer.read(cx).snapshot();
1935        let buffer_id = buffer_snapshot.remote_id();
1936
1937        let mut buffers = self.buffers.borrow_mut();
1938        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| {
1939            self.buffer_changed_since_sync.replace(true);
1940            buffer.update(cx, |buffer, _| {
1941                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1942            });
1943            BufferState {
1944                last_version: buffer_snapshot.version().clone(),
1945                last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1946                excerpts: Default::default(),
1947                _subscriptions: [
1948                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1949                    cx.subscribe(&buffer, Self::on_buffer_event),
1950                ],
1951                buffer: buffer.clone(),
1952            }
1953        });
1954
1955        let mut snapshot = self.snapshot.borrow_mut();
1956
1957        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1958        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1959        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1960        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1961        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1962
1963        let edit_start = ExcerptOffset::new(new_excerpts.summary().text.len);
1964        new_excerpts.update_last(
1965            |excerpt| {
1966                excerpt.has_trailing_newline = true;
1967            },
1968            (),
1969        );
1970
1971        let next_locator = if let Some(excerpt) = cursor.item() {
1972            excerpt.locator.clone()
1973        } else {
1974            Locator::max()
1975        };
1976
1977        let mut excerpts = Vec::new();
1978        while let Some((id, range)) = ranges.next() {
1979            let locator = Locator::between(&prev_locator, &next_locator);
1980            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1981                buffer_state.excerpts.insert(ix, locator.clone());
1982            }
1983            let range = ExcerptRange {
1984                context: buffer_snapshot.anchor_before(&range.context.start)
1985                    ..buffer_snapshot.anchor_after(&range.context.end),
1986                primary: buffer_snapshot.anchor_before(&range.primary.start)
1987                    ..buffer_snapshot.anchor_after(&range.primary.end),
1988            };
1989            excerpts.push((id, range.clone()));
1990            let excerpt = Excerpt::new(
1991                id,
1992                locator.clone(),
1993                buffer_id,
1994                buffer_snapshot.clone(),
1995                range,
1996                ranges.peek().is_some() || cursor.item().is_some(),
1997            );
1998            new_excerpts.push(excerpt, ());
1999            prev_locator = locator.clone();
2000
2001            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
2002                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
2003            }
2004            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
2005        }
2006
2007        let edit_end = ExcerptOffset::new(new_excerpts.summary().text.len);
2008
2009        let suffix = cursor.suffix();
2010        let changed_trailing_excerpt = suffix.is_empty();
2011        new_excerpts.append(suffix, ());
2012        drop(cursor);
2013        snapshot.excerpts = new_excerpts;
2014        snapshot.excerpt_ids = new_excerpt_ids;
2015        if changed_trailing_excerpt {
2016            snapshot.trailing_excerpt_update_count += 1;
2017        }
2018
2019        self.sync_diff_transforms(
2020            &mut snapshot,
2021            vec![Edit {
2022                old: edit_start..edit_start,
2023                new: edit_start..edit_end,
2024            }],
2025            DiffChangeKind::BufferEdited,
2026        );
2027        cx.emit(Event::Edited {
2028            singleton_buffer_edited: false,
2029            edited_buffer: None,
2030        });
2031        cx.emit(Event::ExcerptsAdded {
2032            buffer,
2033            predecessor: prev_excerpt_id,
2034            excerpts,
2035        });
2036        cx.notify();
2037    }
2038
2039    pub fn clear(&mut self, cx: &mut Context<Self>) {
2040        self.sync(cx);
2041        let ids = self.excerpt_ids();
2042        let removed_buffer_ids = self
2043            .buffers
2044            .borrow_mut()
2045            .drain()
2046            .map(|(id, _)| id)
2047            .collect();
2048        self.excerpts_by_path.clear();
2049        self.paths_by_excerpt.clear();
2050        let mut snapshot = self.snapshot.borrow_mut();
2051        let start = ExcerptOffset::new(0);
2052        let prev_len = ExcerptOffset::new(snapshot.excerpts.summary().text.len);
2053        snapshot.excerpts = Default::default();
2054        snapshot.trailing_excerpt_update_count += 1;
2055        snapshot.is_dirty = false;
2056        snapshot.has_deleted_file = false;
2057        snapshot.has_conflict = false;
2058        snapshot.replaced_excerpts.clear();
2059
2060        self.sync_diff_transforms(
2061            &mut snapshot,
2062            vec![Edit {
2063                old: start..prev_len,
2064                new: start..start,
2065            }],
2066            DiffChangeKind::BufferEdited,
2067        );
2068        cx.emit(Event::Edited {
2069            singleton_buffer_edited: false,
2070            edited_buffer: None,
2071        });
2072        cx.emit(Event::ExcerptsRemoved {
2073            ids,
2074            removed_buffer_ids,
2075        });
2076        cx.notify();
2077    }
2078
2079    pub fn excerpts_for_buffer(
2080        &self,
2081        buffer_id: BufferId,
2082        cx: &App,
2083    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
2084        let mut excerpts = Vec::new();
2085        let snapshot = self.read(cx);
2086        let buffers = self.buffers.borrow();
2087        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
2088        if let Some(locators) = buffers.get(&buffer_id).map(|state| &state.excerpts) {
2089            for locator in locators {
2090                cursor.seek_forward(&Some(locator), Bias::Left);
2091                if let Some(excerpt) = cursor.item()
2092                    && excerpt.locator == *locator
2093                {
2094                    excerpts.push((excerpt.id, excerpt.range.clone()));
2095                }
2096            }
2097        }
2098
2099        excerpts
2100    }
2101
2102    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2103        let snapshot = self.read(cx);
2104        let buffers = self.buffers.borrow();
2105        let mut excerpts = snapshot
2106            .excerpts
2107            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
2108        let mut diff_transforms = snapshot
2109            .diff_transforms
2110            .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
2111        diff_transforms.next();
2112        let locators = buffers
2113            .get(&buffer_id)
2114            .into_iter()
2115            .flat_map(|state| &state.excerpts);
2116        let mut result = Vec::new();
2117        for locator in locators {
2118            excerpts.seek_forward(&Some(locator), Bias::Left);
2119            if let Some(excerpt) = excerpts.item()
2120                && excerpt.locator == *locator
2121            {
2122                let excerpt_start = excerpts.start().1.clone();
2123                let excerpt_end = ExcerptDimension(excerpt_start.0 + excerpt.text_summary.lines);
2124
2125                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2126                let overshoot = excerpt_start.0 - diff_transforms.start().0.0;
2127                let start = diff_transforms.start().1.0 + overshoot;
2128
2129                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2130                let overshoot = excerpt_end.0 - diff_transforms.start().0.0;
2131                let end = diff_transforms.start().1.0 + overshoot;
2132
2133                result.push(start..end)
2134            }
2135        }
2136        result
2137    }
2138
2139    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2140        self.snapshot
2141            .borrow()
2142            .excerpts
2143            .iter()
2144            .map(|entry| entry.buffer_id)
2145            .collect()
2146    }
2147
2148    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2149        self.snapshot
2150            .borrow()
2151            .excerpts
2152            .iter()
2153            .map(|entry| entry.id)
2154            .collect()
2155    }
2156
2157    pub fn excerpt_containing(
2158        &self,
2159        position: impl ToOffset,
2160        cx: &App,
2161    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2162        let snapshot = self.read(cx);
2163        let offset = position.to_offset(&snapshot);
2164
2165        let mut cursor = snapshot.cursor::<usize>();
2166        cursor.seek(&offset);
2167        cursor
2168            .excerpt()
2169            .or_else(|| snapshot.excerpts.last())
2170            .map(|excerpt| {
2171                (
2172                    excerpt.id,
2173                    self.buffers
2174                        .borrow()
2175                        .get(&excerpt.buffer_id)
2176                        .unwrap()
2177                        .buffer
2178                        .clone(),
2179                    excerpt.range.context.clone(),
2180                )
2181            })
2182    }
2183
2184    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2185        if let Some(buffer_id) = anchor.buffer_id {
2186            self.buffer(buffer_id)
2187        } else {
2188            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2189            Some(buffer)
2190        }
2191    }
2192
2193    // If point is at the end of the buffer, the last excerpt is returned
2194    pub fn point_to_buffer_offset<T: ToOffset>(
2195        &self,
2196        point: T,
2197        cx: &App,
2198    ) -> Option<(Entity<Buffer>, usize)> {
2199        let snapshot = self.read(cx);
2200        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2201        Some((
2202            self.buffers
2203                .borrow()
2204                .get(&buffer.remote_id())?
2205                .buffer
2206                .clone(),
2207            offset,
2208        ))
2209    }
2210
2211    // If point is at the end of the buffer, the last excerpt is returned
2212    pub fn point_to_buffer_point<T: ToPoint>(
2213        &self,
2214        point: T,
2215        cx: &App,
2216    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2217        let snapshot = self.read(cx);
2218        let (buffer, point, is_main_buffer) =
2219            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2220        Some((
2221            self.buffers
2222                .borrow()
2223                .get(&buffer.remote_id())?
2224                .buffer
2225                .clone(),
2226            point,
2227            is_main_buffer,
2228        ))
2229    }
2230
2231    pub fn buffer_point_to_anchor(
2232        &self,
2233        buffer: &Entity<Buffer>,
2234        point: Point,
2235        cx: &App,
2236    ) -> Option<Anchor> {
2237        let mut found = None;
2238        let snapshot = buffer.read(cx).snapshot();
2239        for (excerpt_id, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2240            let start = range.context.start.to_point(&snapshot);
2241            let end = range.context.end.to_point(&snapshot);
2242            if start <= point && point < end {
2243                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2244                break;
2245            }
2246            if point < start {
2247                found = Some((start, excerpt_id));
2248            }
2249            if point > end {
2250                found = Some((end, excerpt_id));
2251            }
2252        }
2253
2254        found.map(|(point, excerpt_id)| {
2255            let text_anchor = snapshot.anchor_after(point);
2256            Anchor::in_buffer(excerpt_id, snapshot.remote_id(), text_anchor)
2257        })
2258    }
2259
2260    pub fn remove_excerpts(
2261        &mut self,
2262        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2263        cx: &mut Context<Self>,
2264    ) {
2265        self.sync(cx);
2266        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2267        if ids.is_empty() {
2268            return;
2269        }
2270
2271        let mut buffers = self.buffers.borrow_mut();
2272        let mut snapshot = self.snapshot.borrow_mut();
2273        let mut new_excerpts = SumTree::default();
2274        let mut cursor = snapshot
2275            .excerpts
2276            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2277        let mut edits = Vec::new();
2278        let mut excerpt_ids = ids.iter().copied().peekable();
2279        let mut removed_buffer_ids = Vec::new();
2280
2281        while let Some(excerpt_id) = excerpt_ids.next() {
2282            self.paths_by_excerpt.remove(&excerpt_id);
2283            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2284            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2285            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2286
2287            if let Some(mut excerpt) = cursor.item() {
2288                if excerpt.id != excerpt_id {
2289                    continue;
2290                }
2291                let mut old_start = cursor.start().1;
2292
2293                // Skip over the removed excerpt.
2294                'remove_excerpts: loop {
2295                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
2296                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2297                        if buffer_state.excerpts.is_empty() {
2298                            log::debug!(
2299                                "removing buffer and diff for buffer {}",
2300                                excerpt.buffer_id
2301                            );
2302                            buffers.remove(&excerpt.buffer_id);
2303                            removed_buffer_ids.push(excerpt.buffer_id);
2304                        }
2305                    }
2306                    cursor.next();
2307
2308                    // Skip over any subsequent excerpts that are also removed.
2309                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2310                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2311                        if let Some(next_excerpt) = cursor.item()
2312                            && next_excerpt.locator == *next_locator
2313                        {
2314                            excerpt_ids.next();
2315                            excerpt = next_excerpt;
2316                            continue 'remove_excerpts;
2317                        }
2318                    }
2319
2320                    break;
2321                }
2322
2323                // When removing the last excerpt, remove the trailing newline from
2324                // the previous excerpt.
2325                if cursor.item().is_none() && old_start.value > 0 {
2326                    old_start.value -= 1;
2327                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2328                }
2329
2330                // Push an edit for the removal of this run of excerpts.
2331                let old_end = cursor.start().1;
2332                let new_start = ExcerptOffset::new(new_excerpts.summary().text.len);
2333                edits.push(Edit {
2334                    old: old_start..old_end,
2335                    new: new_start..new_start,
2336                });
2337            }
2338        }
2339        let suffix = cursor.suffix();
2340        let changed_trailing_excerpt = suffix.is_empty();
2341        new_excerpts.append(suffix, ());
2342        drop(cursor);
2343        snapshot.excerpts = new_excerpts;
2344        for buffer_id in &removed_buffer_ids {
2345            self.diffs.remove(buffer_id);
2346            snapshot.diffs.remove(buffer_id);
2347        }
2348
2349        if changed_trailing_excerpt {
2350            snapshot.trailing_excerpt_update_count += 1;
2351        }
2352
2353        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2354        self.buffer_changed_since_sync.replace(true);
2355        cx.emit(Event::Edited {
2356            singleton_buffer_edited: false,
2357            edited_buffer: None,
2358        });
2359        cx.emit(Event::ExcerptsRemoved {
2360            ids,
2361            removed_buffer_ids,
2362        });
2363        cx.notify();
2364    }
2365
2366    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2367        &self,
2368        anchors: Anchors,
2369        cx: &mut Context<Self>,
2370    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2371        let borrow = self.buffers.borrow();
2372        let mut error = None;
2373        let mut futures = Vec::new();
2374        for anchor in anchors {
2375            if let Some(buffer_id) = anchor.buffer_id {
2376                if let Some(buffer) = borrow.get(&buffer_id) {
2377                    buffer.buffer.update(cx, |buffer, _| {
2378                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2379                    });
2380                } else {
2381                    error = Some(anyhow!(
2382                        "buffer {buffer_id} is not part of this multi-buffer"
2383                    ));
2384                    break;
2385                }
2386            }
2387        }
2388        async move {
2389            if let Some(error) = error {
2390                Err(error)?;
2391            }
2392            for future in futures {
2393                future.await?;
2394            }
2395            Ok(())
2396        }
2397    }
2398
2399    pub fn text_anchor_for_position<T: ToOffset>(
2400        &self,
2401        position: T,
2402        cx: &App,
2403    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2404        let snapshot = self.read(cx);
2405        let anchor = snapshot.anchor_before(position);
2406        let buffer = self
2407            .buffers
2408            .borrow()
2409            .get(&anchor.buffer_id?)?
2410            .buffer
2411            .clone();
2412        Some((buffer, anchor.text_anchor))
2413    }
2414
2415    fn on_buffer_event(
2416        &mut self,
2417        buffer: Entity<Buffer>,
2418        event: &language::BufferEvent,
2419        cx: &mut Context<Self>,
2420    ) {
2421        use language::BufferEvent;
2422        cx.emit(match event {
2423            BufferEvent::Edited => Event::Edited {
2424                singleton_buffer_edited: true,
2425                edited_buffer: Some(buffer),
2426            },
2427            BufferEvent::DirtyChanged => Event::DirtyChanged,
2428            BufferEvent::Saved => Event::Saved,
2429            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2430            BufferEvent::Reloaded => Event::Reloaded,
2431            BufferEvent::LanguageChanged => Event::LanguageChanged(buffer.read(cx).remote_id()),
2432            BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
2433            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2434            BufferEvent::CapabilityChanged => {
2435                self.capability = buffer.read(cx).capability();
2436                return;
2437            }
2438            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2439        });
2440    }
2441
2442    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2443        self.sync(cx);
2444        let mut snapshot = self.snapshot.borrow_mut();
2445        let diff = diff.read(cx);
2446        let buffer_id = diff.buffer_id;
2447        let diff = diff.snapshot(cx);
2448        snapshot.diffs.insert(buffer_id, diff);
2449    }
2450
2451    fn buffer_diff_changed(
2452        &mut self,
2453        diff: Entity<BufferDiff>,
2454        range: Range<text::Anchor>,
2455        cx: &mut Context<Self>,
2456    ) {
2457        self.sync(cx);
2458        self.buffer_changed_since_sync.replace(true);
2459
2460        let diff = diff.read(cx);
2461        let buffer_id = diff.buffer_id;
2462        let buffers = self.buffers.borrow();
2463        let Some(buffer_state) = buffers.get(&buffer_id) else {
2464            return;
2465        };
2466
2467        let buffer = buffer_state.buffer.read(cx);
2468        let diff_change_range = range.to_offset(buffer);
2469
2470        let new_diff = diff.snapshot(cx);
2471        let mut snapshot = self.snapshot.borrow_mut();
2472        let base_text_changed = snapshot
2473            .diffs
2474            .get(&buffer_id)
2475            .is_none_or(|old_diff| !new_diff.base_texts_eq(old_diff));
2476
2477        snapshot.diffs.insert(buffer_id, new_diff);
2478
2479        let mut excerpt_edits = Vec::new();
2480        for locator in &buffer_state.excerpts {
2481            let mut cursor = snapshot
2482                .excerpts
2483                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2484            cursor.seek_forward(&Some(locator), Bias::Left);
2485            if let Some(excerpt) = cursor.item()
2486                && excerpt.locator == *locator
2487            {
2488                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
2489                if diff_change_range.end < excerpt_buffer_range.start
2490                    || diff_change_range.start > excerpt_buffer_range.end
2491                {
2492                    continue;
2493                }
2494                let excerpt_start = cursor.start().1;
2495                let excerpt_len = ExcerptOffset::new(excerpt.text_summary.len);
2496                let diff_change_start_in_excerpt = ExcerptOffset::new(
2497                    diff_change_range
2498                        .start
2499                        .saturating_sub(excerpt_buffer_range.start),
2500                );
2501                let diff_change_end_in_excerpt = ExcerptOffset::new(
2502                    diff_change_range
2503                        .end
2504                        .saturating_sub(excerpt_buffer_range.start),
2505                );
2506                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
2507                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
2508                excerpt_edits.push(Edit {
2509                    old: edit_start..edit_end,
2510                    new: edit_start..edit_end,
2511                });
2512            }
2513        }
2514
2515        self.sync_diff_transforms(
2516            &mut snapshot,
2517            excerpt_edits,
2518            DiffChangeKind::DiffUpdated {
2519                base_changed: base_text_changed,
2520            },
2521        );
2522        cx.emit(Event::Edited {
2523            singleton_buffer_edited: false,
2524            edited_buffer: None,
2525        });
2526    }
2527
2528    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2529        self.buffers
2530            .borrow()
2531            .values()
2532            .map(|state| state.buffer.clone())
2533            .collect()
2534    }
2535
2536    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2537        self.buffers.borrow().keys().copied().collect()
2538    }
2539
2540    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2541        self.buffers
2542            .borrow()
2543            .get(&buffer_id)
2544            .map(|state| state.buffer.clone())
2545    }
2546
2547    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2548        self.point_to_buffer_offset(point, cx)
2549            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2550    }
2551
2552    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2553        let buffer_id = self
2554            .snapshot
2555            .borrow()
2556            .excerpts
2557            .first()
2558            .map(|excerpt| excerpt.buffer.remote_id());
2559        buffer_id
2560            .and_then(|buffer_id| self.buffer(buffer_id))
2561            .map(|buffer| {
2562                let buffer = buffer.read(cx);
2563                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2564            })
2565            .unwrap_or_else(move || self.language_settings_at(0, cx))
2566    }
2567
2568    pub fn language_settings_at<'a, T: ToOffset>(
2569        &'a self,
2570        point: T,
2571        cx: &'a App,
2572    ) -> Cow<'a, LanguageSettings> {
2573        let mut language = None;
2574        let mut file = None;
2575        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2576            let buffer = buffer.read(cx);
2577            language = buffer.language_at(offset);
2578            file = buffer.file();
2579        }
2580        language_settings(language.map(|l| l.name()), file, cx)
2581    }
2582
2583    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2584        self.buffers
2585            .borrow()
2586            .values()
2587            .for_each(|state| f(&state.buffer))
2588    }
2589
2590    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2591        if let Some(title) = self.title.as_ref() {
2592            return title.into();
2593        }
2594
2595        if let Some(buffer) = self.as_singleton() {
2596            let buffer = buffer.read(cx);
2597
2598            if let Some(file) = buffer.file() {
2599                return file.file_name(cx).into();
2600            }
2601
2602            if let Some(title) = self.buffer_content_title(buffer) {
2603                return title;
2604            }
2605        };
2606
2607        "untitled".into()
2608    }
2609
2610    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2611        let mut is_leading_whitespace = true;
2612        let mut count = 0;
2613        let mut prev_was_space = false;
2614        let mut title = String::new();
2615
2616        for ch in buffer.snapshot().chars() {
2617            if is_leading_whitespace && ch.is_whitespace() {
2618                continue;
2619            }
2620
2621            is_leading_whitespace = false;
2622
2623            if ch == '\n' || count >= 40 {
2624                break;
2625            }
2626
2627            if ch.is_whitespace() {
2628                if !prev_was_space {
2629                    title.push(' ');
2630                    count += 1;
2631                    prev_was_space = true;
2632                }
2633            } else {
2634                title.push(ch);
2635                count += 1;
2636                prev_was_space = false;
2637            }
2638        }
2639
2640        let title = title.trim_end().to_string();
2641
2642        if title.is_empty() {
2643            return None;
2644        }
2645
2646        Some(title.into())
2647    }
2648
2649    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2650        self.title = Some(title);
2651        cx.notify();
2652    }
2653
2654    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2655    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2656        for buffer_state in self.buffers.borrow().values() {
2657            buffer_state
2658                .buffer
2659                .update(cx, |buffer, _cx| buffer.refresh_preview());
2660        }
2661    }
2662
2663    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2664    pub fn preserve_preview(&self, cx: &App) -> bool {
2665        self.buffers
2666            .borrow()
2667            .values()
2668            .all(|state| state.buffer.read(cx).preserve_preview())
2669    }
2670
2671    #[cfg(any(test, feature = "test-support"))]
2672    pub fn is_parsing(&self, cx: &App) -> bool {
2673        self.as_singleton().unwrap().read(cx).is_parsing()
2674    }
2675
2676    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2677        let buffer_id = diff.read(cx).buffer_id;
2678        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2679        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2680    }
2681
2682    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2683        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2684    }
2685
2686    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2687        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2688    }
2689
2690    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2691        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2692    }
2693
2694    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2695        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2696        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2697    }
2698
2699    pub fn all_diff_hunks_expanded(&self) -> bool {
2700        self.snapshot.borrow().all_diff_hunks_expanded
2701    }
2702
2703    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2704        self.snapshot.borrow_mut().all_diff_hunks_expanded = false;
2705        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2706    }
2707
2708    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2709        self.read(cx)
2710            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2711            .nth(1)
2712            .is_some()
2713    }
2714
2715    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2716        let snapshot = self.read(cx);
2717        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2718        let offset_range = range.to_offset(&snapshot);
2719        cursor.seek(&offset_range.start, Bias::Left);
2720        while let Some(item) = cursor.item() {
2721            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2722                break;
2723            }
2724            if item.hunk_info().is_some() {
2725                return true;
2726            }
2727            cursor.next();
2728        }
2729        false
2730    }
2731
2732    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2733        let snapshot = self.read(cx);
2734        let mut cursor = snapshot.diff_transforms.cursor::<usize>(());
2735        for range in ranges {
2736            let range = range.to_point(&snapshot);
2737            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2738            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2739            let start = start.saturating_sub(1);
2740            let end = snapshot.len().min(end + 1);
2741            cursor.seek(&start, Bias::Right);
2742            while let Some(item) = cursor.item() {
2743                if *cursor.start() >= end {
2744                    break;
2745                }
2746                if item.hunk_info().is_some() {
2747                    return true;
2748                }
2749                cursor.next();
2750            }
2751        }
2752        false
2753    }
2754
2755    pub fn expand_or_collapse_diff_hunks_inner(
2756        &mut self,
2757        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2758        expand: bool,
2759        cx: &mut Context<Self>,
2760    ) {
2761        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2762            return;
2763        }
2764        self.sync(cx);
2765        let mut snapshot = self.snapshot.borrow_mut();
2766        let mut excerpt_edits = Vec::new();
2767        let mut last_hunk_row = None;
2768        for (range, end_excerpt_id) in ranges {
2769            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2770                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2771                    continue;
2772                }
2773                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2774                    continue;
2775                }
2776                let start = Anchor::in_buffer(
2777                    diff_hunk.excerpt_id,
2778                    diff_hunk.buffer_id,
2779                    diff_hunk.buffer_range.start,
2780                );
2781                let end = Anchor::in_buffer(
2782                    diff_hunk.excerpt_id,
2783                    diff_hunk.buffer_id,
2784                    diff_hunk.buffer_range.end,
2785                );
2786                let start = snapshot.excerpt_offset_for_anchor(&start);
2787                let end = snapshot.excerpt_offset_for_anchor(&end);
2788                last_hunk_row = Some(diff_hunk.row_range.start);
2789                excerpt_edits.push(text::Edit {
2790                    old: start..end,
2791                    new: start..end,
2792                });
2793            }
2794        }
2795
2796        self.sync_diff_transforms(
2797            &mut snapshot,
2798            excerpt_edits,
2799            DiffChangeKind::ExpandOrCollapseHunks { expand },
2800        );
2801        cx.emit(Event::DiffHunksToggled);
2802        cx.emit(Event::Edited {
2803            singleton_buffer_edited: false,
2804            edited_buffer: None,
2805        });
2806    }
2807
2808    pub fn expand_or_collapse_diff_hunks(
2809        &mut self,
2810        ranges: Vec<Range<Anchor>>,
2811        expand: bool,
2812        cx: &mut Context<Self>,
2813    ) {
2814        let snapshot = self.snapshot.borrow().clone();
2815        let ranges = ranges.iter().map(move |range| {
2816            let end_excerpt_id = range.end.excerpt_id;
2817            let range = range.to_point(&snapshot);
2818            let mut peek_end = range.end;
2819            if range.end.row < snapshot.max_row().0 {
2820                peek_end = Point::new(range.end.row + 1, 0);
2821            };
2822            (range.start..peek_end, end_excerpt_id)
2823        });
2824        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2825    }
2826
2827    pub fn resize_excerpt(
2828        &mut self,
2829        id: ExcerptId,
2830        range: Range<text::Anchor>,
2831        cx: &mut Context<Self>,
2832    ) {
2833        self.sync(cx);
2834
2835        let mut snapshot = self.snapshot.borrow_mut();
2836        let locator = snapshot.excerpt_locator_for_id(id);
2837        let mut new_excerpts = SumTree::default();
2838        let mut cursor = snapshot
2839            .excerpts
2840            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2841        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2842
2843        let prefix = cursor.slice(&Some(locator), Bias::Left);
2844        new_excerpts.append(prefix, ());
2845
2846        let mut excerpt = cursor.item().unwrap().clone();
2847        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2848
2849        excerpt.range.context.start = range.start;
2850        excerpt.range.context.end = range.end;
2851        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2852
2853        excerpt.text_summary = excerpt
2854            .buffer
2855            .text_summary_for_range(excerpt.range.context.clone());
2856
2857        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2858        let old_start_offset = cursor.start().1;
2859        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2860        let edit = Edit {
2861            old: old_start_offset..old_start_offset + old_text_len,
2862            new: new_start_offset..new_start_offset + new_text_len,
2863        };
2864
2865        if let Some(last_edit) = edits.last_mut() {
2866            if last_edit.old.end == edit.old.start {
2867                last_edit.old.end = edit.old.end;
2868                last_edit.new.end = edit.new.end;
2869            } else {
2870                edits.push(edit);
2871            }
2872        } else {
2873            edits.push(edit);
2874        }
2875
2876        new_excerpts.push(excerpt, ());
2877
2878        cursor.next();
2879
2880        new_excerpts.append(cursor.suffix(), ());
2881
2882        drop(cursor);
2883        snapshot.excerpts = new_excerpts;
2884
2885        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2886        cx.emit(Event::Edited {
2887            singleton_buffer_edited: false,
2888            edited_buffer: None,
2889        });
2890        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2891        cx.notify();
2892    }
2893
2894    pub fn expand_excerpts(
2895        &mut self,
2896        ids: impl IntoIterator<Item = ExcerptId>,
2897        line_count: u32,
2898        direction: ExpandExcerptDirection,
2899        cx: &mut Context<Self>,
2900    ) {
2901        if line_count == 0 {
2902            return;
2903        }
2904        self.sync(cx);
2905        if !self.excerpts_by_path.is_empty() {
2906            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2907            return;
2908        }
2909        let mut snapshot = self.snapshot.borrow_mut();
2910
2911        let ids = ids.into_iter().collect::<Vec<_>>();
2912        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2913        let mut new_excerpts = SumTree::default();
2914        let mut cursor = snapshot
2915            .excerpts
2916            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2917        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2918
2919        for locator in &locators {
2920            let prefix = cursor.slice(&Some(locator), Bias::Left);
2921            new_excerpts.append(prefix, ());
2922
2923            let mut excerpt = cursor.item().unwrap().clone();
2924            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2925
2926            let up_line_count = if direction.should_expand_up() {
2927                line_count
2928            } else {
2929                0
2930            };
2931
2932            let start_row = excerpt
2933                .range
2934                .context
2935                .start
2936                .to_point(&excerpt.buffer)
2937                .row
2938                .saturating_sub(up_line_count);
2939            let start_point = Point::new(start_row, 0);
2940            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2941
2942            let down_line_count = if direction.should_expand_down() {
2943                line_count
2944            } else {
2945                0
2946            };
2947
2948            let mut end_point = excerpt.buffer.clip_point(
2949                excerpt.range.context.end.to_point(&excerpt.buffer)
2950                    + Point::new(down_line_count, 0),
2951                Bias::Left,
2952            );
2953            end_point.column = excerpt.buffer.line_len(end_point.row);
2954            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2955            excerpt.max_buffer_row = end_point.row;
2956
2957            excerpt.text_summary = excerpt
2958                .buffer
2959                .text_summary_for_range(excerpt.range.context.clone());
2960
2961            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2962            let old_start_offset = cursor.start().1;
2963            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2964            let edit = Edit {
2965                old: old_start_offset..old_start_offset + old_text_len,
2966                new: new_start_offset..new_start_offset + new_text_len,
2967            };
2968
2969            if let Some(last_edit) = edits.last_mut() {
2970                if last_edit.old.end == edit.old.start {
2971                    last_edit.old.end = edit.old.end;
2972                    last_edit.new.end = edit.new.end;
2973                } else {
2974                    edits.push(edit);
2975                }
2976            } else {
2977                edits.push(edit);
2978            }
2979
2980            new_excerpts.push(excerpt, ());
2981
2982            cursor.next();
2983        }
2984
2985        new_excerpts.append(cursor.suffix(), ());
2986
2987        drop(cursor);
2988        snapshot.excerpts = new_excerpts;
2989
2990        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2991        cx.emit(Event::Edited {
2992            singleton_buffer_edited: false,
2993            edited_buffer: None,
2994        });
2995        cx.emit(Event::ExcerptsExpanded { ids });
2996        cx.notify();
2997    }
2998
2999    fn sync(&self, cx: &App) {
3000        let changed = self.buffer_changed_since_sync.replace(false);
3001        if !changed {
3002            return;
3003        }
3004
3005        let mut snapshot = self.snapshot.borrow_mut();
3006        let mut excerpts_to_edit = Vec::new();
3007        let mut non_text_state_updated = false;
3008        let mut is_dirty = false;
3009        let mut has_deleted_file = false;
3010        let mut has_conflict = false;
3011        let mut edited = false;
3012        let mut buffers = self.buffers.borrow_mut();
3013        for buffer_state in buffers.values_mut() {
3014            let buffer = buffer_state.buffer.read(cx);
3015            let version = buffer.version();
3016            let non_text_state_update_count = buffer.non_text_state_update_count();
3017
3018            let buffer_edited = version.changed_since(&buffer_state.last_version);
3019            let buffer_non_text_state_updated =
3020                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
3021            if buffer_edited || buffer_non_text_state_updated {
3022                buffer_state.last_version = version;
3023                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
3024                excerpts_to_edit.extend(
3025                    buffer_state
3026                        .excerpts
3027                        .iter()
3028                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3029                );
3030            }
3031
3032            edited |= buffer_edited;
3033            non_text_state_updated |= buffer_non_text_state_updated;
3034            is_dirty |= buffer.is_dirty();
3035            has_deleted_file |= buffer
3036                .file()
3037                .is_some_and(|file| file.disk_state() == DiskState::Deleted);
3038            has_conflict |= buffer.has_conflict();
3039        }
3040        if edited {
3041            snapshot.edit_count += 1;
3042        }
3043        if non_text_state_updated {
3044            snapshot.non_text_state_update_count += 1;
3045        }
3046        snapshot.is_dirty = is_dirty;
3047        snapshot.has_deleted_file = has_deleted_file;
3048        snapshot.has_conflict = has_conflict;
3049
3050        for (id, diff) in self.diffs.iter() {
3051            if snapshot.diffs.get(id).is_none() {
3052                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
3053            }
3054        }
3055
3056        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
3057
3058        let mut edits = Vec::new();
3059        let mut new_excerpts = SumTree::default();
3060        let mut cursor = snapshot
3061            .excerpts
3062            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3063
3064        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3065            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3066            let old_excerpt = cursor.item().unwrap();
3067            let buffer = buffer.read(cx);
3068            let buffer_id = buffer.remote_id();
3069
3070            let mut new_excerpt;
3071            if buffer_edited {
3072                edits.extend(
3073                    buffer
3074                        .edits_since_in_range::<usize>(
3075                            old_excerpt.buffer.version(),
3076                            old_excerpt.range.context.clone(),
3077                        )
3078                        .map(|edit| {
3079                            let excerpt_old_start = cursor.start().1;
3080                            let excerpt_new_start =
3081                                ExcerptOffset::new(new_excerpts.summary().text.len);
3082                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
3083                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
3084                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
3085                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
3086                            Edit {
3087                                old: old_start..old_end,
3088                                new: new_start..new_end,
3089                            }
3090                        }),
3091                );
3092
3093                new_excerpt = Excerpt::new(
3094                    old_excerpt.id,
3095                    locator.clone(),
3096                    buffer_id,
3097                    buffer.snapshot(),
3098                    old_excerpt.range.clone(),
3099                    old_excerpt.has_trailing_newline,
3100                );
3101            } else {
3102                new_excerpt = old_excerpt.clone();
3103                new_excerpt.buffer = buffer.snapshot();
3104            }
3105
3106            new_excerpts.push(new_excerpt, ());
3107            cursor.next();
3108        }
3109        new_excerpts.append(cursor.suffix(), ());
3110
3111        drop(cursor);
3112        snapshot.excerpts = new_excerpts;
3113
3114        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3115    }
3116
3117    fn sync_diff_transforms(
3118        &self,
3119        snapshot: &mut MultiBufferSnapshot,
3120        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3121        change_kind: DiffChangeKind,
3122    ) {
3123        if excerpt_edits.is_empty() {
3124            return;
3125        }
3126
3127        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3128        let mut old_diff_transforms = snapshot
3129            .diff_transforms
3130            .cursor::<Dimensions<ExcerptOffset, usize>>(());
3131        let mut new_diff_transforms = SumTree::default();
3132        let mut old_expanded_hunks = HashSet::default();
3133        let mut output_edits = Vec::new();
3134        let mut output_delta = 0_isize;
3135        let mut at_transform_boundary = true;
3136        let mut end_of_current_insert = None;
3137
3138        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3139        while let Some(edit) = excerpt_edits.next() {
3140            excerpts.seek_forward(&edit.new.start, Bias::Right);
3141            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3142                excerpts.prev();
3143            }
3144
3145            // Keep any transforms that are before the edit.
3146            if at_transform_boundary {
3147                at_transform_boundary = false;
3148                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3149                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3150                if let Some(transform) = old_diff_transforms.item()
3151                    && old_diff_transforms.end().0 == edit.old.start
3152                    && old_diff_transforms.start().0 < edit.old.start
3153                {
3154                    self.push_diff_transform(&mut new_diff_transforms, transform.clone());
3155                    old_diff_transforms.next();
3156                }
3157            }
3158
3159            // Compute the start of the edit in output coordinates.
3160            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
3161            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3162            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
3163
3164            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
3165                &edit,
3166                &mut excerpts,
3167                &mut old_diff_transforms,
3168                &mut new_diff_transforms,
3169                &mut end_of_current_insert,
3170                &mut old_expanded_hunks,
3171                snapshot,
3172                change_kind,
3173            );
3174
3175            // Compute the end of the edit in output coordinates.
3176            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3177            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3178            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
3179            let edit_new_end =
3180                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
3181            let output_edit = Edit {
3182                old: edit_old_start..edit_old_end,
3183                new: edit_new_start..edit_new_end,
3184            };
3185
3186            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3187            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3188            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3189                output_edits.push(output_edit);
3190            }
3191
3192            // If this is the last edit that intersects the current diff transform,
3193            // then recreate the content up to the end of this transform, to prepare
3194            // for reusing additional slices of the old transforms.
3195            if excerpt_edits
3196                .peek()
3197                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3198            {
3199                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3200                    && match old_diff_transforms.item() {
3201                        Some(DiffTransform::BufferContent {
3202                            inserted_hunk_info: Some(hunk),
3203                            ..
3204                        }) => excerpts.item().is_some_and(|excerpt| {
3205                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3206                        }),
3207                        _ => true,
3208                    };
3209
3210                let mut excerpt_offset = edit.new.end;
3211                if !keep_next_old_transform {
3212                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3213                    old_diff_transforms.next();
3214                }
3215
3216                old_expanded_hunks.clear();
3217                self.push_buffer_content_transform(
3218                    snapshot,
3219                    &mut new_diff_transforms,
3220                    excerpt_offset,
3221                    end_of_current_insert,
3222                );
3223                at_transform_boundary = true;
3224            }
3225        }
3226
3227        // Keep any transforms that are after the last edit.
3228        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3229
3230        // Ensure there's always at least one buffer content transform.
3231        if new_diff_transforms.is_empty() {
3232            new_diff_transforms.push(
3233                DiffTransform::BufferContent {
3234                    summary: Default::default(),
3235                    inserted_hunk_info: None,
3236                },
3237                (),
3238            );
3239        }
3240
3241        self.subscriptions.publish(output_edits);
3242        drop(old_diff_transforms);
3243        drop(excerpts);
3244        snapshot.diff_transforms = new_diff_transforms;
3245        snapshot.edit_count += 1;
3246
3247        #[cfg(any(test, feature = "test-support"))]
3248        snapshot.check_invariants();
3249    }
3250
3251    fn recompute_diff_transforms_for_edit(
3252        &self,
3253        edit: &Edit<TypedOffset<Excerpt>>,
3254        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
3255        old_diff_transforms: &mut Cursor<DiffTransform, Dimensions<TypedOffset<Excerpt>, usize>>,
3256        new_diff_transforms: &mut SumTree<DiffTransform>,
3257        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
3258        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3259        snapshot: &MultiBufferSnapshot,
3260        change_kind: DiffChangeKind,
3261    ) -> bool {
3262        log::trace!(
3263            "recomputing diff transform for edit {:?} => {:?}",
3264            edit.old.start.value..edit.old.end.value,
3265            edit.new.start.value..edit.new.end.value
3266        );
3267
3268        // Record which hunks were previously expanded.
3269        while let Some(item) = old_diff_transforms.item() {
3270            if let Some(hunk_info) = item.hunk_info() {
3271                log::trace!(
3272                    "previously expanded hunk at {}",
3273                    old_diff_transforms.start().0
3274                );
3275                old_expanded_hunks.insert(hunk_info);
3276            }
3277            if old_diff_transforms.end().0 > edit.old.end {
3278                break;
3279            }
3280            old_diff_transforms.next();
3281        }
3282
3283        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3284        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3285        if old_expanded_hunks.is_empty()
3286            && change_kind == DiffChangeKind::BufferEdited
3287            && !all_diff_hunks_expanded
3288        {
3289            return false;
3290        }
3291
3292        // Visit each excerpt that intersects the edit.
3293        let mut did_expand_hunks = false;
3294        while let Some(excerpt) = excerpts.item() {
3295            // Recompute the expanded hunks in the portion of the excerpt that
3296            // intersects the edit.
3297            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3298                let buffer = &excerpt.buffer;
3299                let excerpt_start = *excerpts.start();
3300                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
3301                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3302                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3303                let edit_buffer_start =
3304                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
3305                let edit_buffer_end =
3306                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
3307                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3308                let edit_anchor_range =
3309                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
3310
3311                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3312                    if hunk.is_created_file() && !all_diff_hunks_expanded {
3313                        continue;
3314                    }
3315
3316                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3317                    if hunk_buffer_range.start < excerpt_buffer_start {
3318                        log::trace!("skipping hunk that starts before excerpt");
3319                        continue;
3320                    }
3321
3322                    let hunk_info = DiffTransformHunkInfo {
3323                        excerpt_id: excerpt.id,
3324                        hunk_start_anchor: hunk.buffer_range.start,
3325                        hunk_secondary_status: hunk.secondary_status,
3326                    };
3327
3328                    let hunk_excerpt_start = excerpt_start
3329                        + ExcerptOffset::new(
3330                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3331                        );
3332                    let hunk_excerpt_end = excerpt_end.min(
3333                        excerpt_start
3334                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3335                    );
3336
3337                    self.push_buffer_content_transform(
3338                        snapshot,
3339                        new_diff_transforms,
3340                        hunk_excerpt_start,
3341                        *end_of_current_insert,
3342                    );
3343
3344                    // For every existing hunk, determine if it was previously expanded
3345                    // and if it should currently be expanded.
3346                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3347                    let should_expand_hunk = match &change_kind {
3348                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3349                            was_previously_expanded || all_diff_hunks_expanded
3350                        }
3351                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3352                            let intersects = hunk_buffer_range.is_empty()
3353                                || hunk_buffer_range.end > edit_buffer_start;
3354                            if *expand {
3355                                intersects || was_previously_expanded || all_diff_hunks_expanded
3356                            } else {
3357                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3358                            }
3359                        }
3360                        _ => was_previously_expanded || all_diff_hunks_expanded,
3361                    };
3362
3363                    if should_expand_hunk {
3364                        did_expand_hunks = true;
3365                        log::trace!(
3366                            "expanding hunk {:?}, excerpt:{:?}",
3367                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3368                            excerpt.id
3369                        );
3370
3371                        if !hunk.diff_base_byte_range.is_empty()
3372                            && hunk_buffer_range.start >= edit_buffer_start
3373                            && hunk_buffer_range.start <= excerpt_buffer_end
3374                        {
3375                            let base_text = diff.base_text();
3376                            let mut text_cursor =
3377                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3378                            let mut base_text_summary =
3379                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3380
3381                            let mut has_trailing_newline = false;
3382                            if base_text_summary.last_line_chars > 0 {
3383                                base_text_summary += TextSummary::newline();
3384                                has_trailing_newline = true;
3385                            }
3386
3387                            new_diff_transforms.push(
3388                                DiffTransform::DeletedHunk {
3389                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3390                                    summary: base_text_summary,
3391                                    buffer_id: excerpt.buffer_id,
3392                                    hunk_info,
3393                                    has_trailing_newline,
3394                                },
3395                                (),
3396                            );
3397                        }
3398
3399                        if !hunk_buffer_range.is_empty() {
3400                            *end_of_current_insert =
3401                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3402                        }
3403                    }
3404                }
3405            }
3406
3407            if excerpts.end() <= edit.new.end {
3408                excerpts.next();
3409            } else {
3410                break;
3411            }
3412        }
3413
3414        did_expand_hunks || !old_expanded_hunks.is_empty()
3415    }
3416
3417    fn append_diff_transforms(
3418        &self,
3419        new_transforms: &mut SumTree<DiffTransform>,
3420        subtree: SumTree<DiffTransform>,
3421    ) {
3422        if let Some(DiffTransform::BufferContent {
3423            inserted_hunk_info,
3424            summary,
3425        }) = subtree.first()
3426            && self.extend_last_buffer_content_transform(
3427                new_transforms,
3428                *inserted_hunk_info,
3429                *summary,
3430            )
3431        {
3432            let mut cursor = subtree.cursor::<()>(());
3433            cursor.next();
3434            cursor.next();
3435            new_transforms.append(cursor.suffix(), ());
3436            return;
3437        }
3438        new_transforms.append(subtree, ());
3439    }
3440
3441    fn push_diff_transform(
3442        &self,
3443        new_transforms: &mut SumTree<DiffTransform>,
3444        transform: DiffTransform,
3445    ) {
3446        if let DiffTransform::BufferContent {
3447            inserted_hunk_info: inserted_hunk_anchor,
3448            summary,
3449        } = transform
3450            && self.extend_last_buffer_content_transform(
3451                new_transforms,
3452                inserted_hunk_anchor,
3453                summary,
3454            )
3455        {
3456            return;
3457        }
3458        new_transforms.push(transform, ());
3459    }
3460
3461    fn push_buffer_content_transform(
3462        &self,
3463        old_snapshot: &MultiBufferSnapshot,
3464        new_transforms: &mut SumTree<DiffTransform>,
3465        end_offset: ExcerptOffset,
3466        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3467    ) {
3468        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3469            (end_offset.min(insertion_end_offset), Some(hunk_info))
3470        });
3471        let unchanged_region = [(end_offset, None)];
3472
3473        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3474        {
3475            let start_offset = new_transforms.summary().excerpt_len();
3476            if end_offset <= start_offset {
3477                continue;
3478            }
3479            let summary_to_add = old_snapshot
3480                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3481
3482            if !self.extend_last_buffer_content_transform(
3483                new_transforms,
3484                inserted_hunk_info,
3485                summary_to_add,
3486            ) {
3487                new_transforms.push(
3488                    DiffTransform::BufferContent {
3489                        summary: summary_to_add,
3490                        inserted_hunk_info,
3491                    },
3492                    (),
3493                )
3494            }
3495        }
3496    }
3497
3498    fn extend_last_buffer_content_transform(
3499        &self,
3500        new_transforms: &mut SumTree<DiffTransform>,
3501        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3502        summary_to_add: TextSummary,
3503    ) -> bool {
3504        let mut did_extend = false;
3505        new_transforms.update_last(
3506            |last_transform| {
3507                if let DiffTransform::BufferContent {
3508                    summary,
3509                    inserted_hunk_info: inserted_hunk_anchor,
3510                } = last_transform
3511                    && *inserted_hunk_anchor == new_inserted_hunk_info
3512                {
3513                    *summary += summary_to_add;
3514                    did_extend = true;
3515                }
3516            },
3517            (),
3518        );
3519        did_extend
3520    }
3521}
3522
3523fn build_excerpt_ranges(
3524    ranges: impl IntoIterator<Item = Range<Point>>,
3525    context_line_count: u32,
3526    buffer_snapshot: &BufferSnapshot,
3527) -> Vec<ExcerptRange<Point>> {
3528    ranges
3529        .into_iter()
3530        .map(|range| {
3531            let start_row = range.start.row.saturating_sub(context_line_count);
3532            let start = Point::new(start_row, 0);
3533            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3534            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3535            ExcerptRange {
3536                context: start..end,
3537                primary: range,
3538            }
3539        })
3540        .collect()
3541}
3542
3543#[cfg(any(test, feature = "test-support"))]
3544impl MultiBuffer {
3545    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3546        let buffer = cx.new(|cx| Buffer::local(text, cx));
3547        cx.new(|cx| Self::singleton(buffer, cx))
3548    }
3549
3550    pub fn build_multi<const COUNT: usize>(
3551        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3552        cx: &mut gpui::App,
3553    ) -> Entity<Self> {
3554        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3555        for (text, ranges) in excerpts {
3556            let buffer = cx.new(|cx| Buffer::local(text, cx));
3557            let excerpt_ranges = ranges.into_iter().map(ExcerptRange::new);
3558            multi.update(cx, |multi, cx| {
3559                multi.push_excerpts(buffer, excerpt_ranges, cx)
3560            });
3561        }
3562
3563        multi
3564    }
3565
3566    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3567        cx.new(|cx| Self::singleton(buffer, cx))
3568    }
3569
3570    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3571        cx.new(|cx| {
3572            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3573            let mutation_count = rng.random_range(1..=5);
3574            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3575            multibuffer
3576        })
3577    }
3578
3579    pub fn randomly_edit(
3580        &mut self,
3581        rng: &mut impl rand::Rng,
3582        edit_count: usize,
3583        cx: &mut Context<Self>,
3584    ) {
3585        use util::RandomCharIter;
3586
3587        let snapshot = self.read(cx);
3588        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3589        let mut last_end = None;
3590        for _ in 0..edit_count {
3591            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3592                break;
3593            }
3594
3595            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3596            let end =
3597                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3598            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3599            last_end = Some(end);
3600
3601            let mut range = start..end;
3602            if rng.random_bool(0.2) {
3603                mem::swap(&mut range.start, &mut range.end);
3604            }
3605
3606            let new_text_len = rng.random_range(0..10);
3607            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3608
3609            edits.push((range, new_text.into()));
3610        }
3611        log::info!("mutating multi-buffer with {:?}", edits);
3612        drop(snapshot);
3613
3614        self.edit(edits, None, cx);
3615    }
3616
3617    pub fn randomly_edit_excerpts(
3618        &mut self,
3619        rng: &mut impl rand::Rng,
3620        mutation_count: usize,
3621        cx: &mut Context<Self>,
3622    ) {
3623        use rand::prelude::*;
3624        use std::env;
3625        use util::RandomCharIter;
3626
3627        let max_excerpts = env::var("MAX_EXCERPTS")
3628            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3629            .unwrap_or(5);
3630
3631        let mut buffers = Vec::new();
3632        for _ in 0..mutation_count {
3633            if rng.random_bool(0.05) {
3634                log::info!("Clearing multi-buffer");
3635                self.clear(cx);
3636                continue;
3637            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3638                let ids = self.excerpt_ids();
3639                let mut excerpts = HashSet::default();
3640                for _ in 0..rng.random_range(0..ids.len()) {
3641                    excerpts.extend(ids.choose(rng).copied());
3642                }
3643
3644                let line_count = rng.random_range(0..5);
3645
3646                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3647
3648                self.expand_excerpts(
3649                    excerpts.iter().cloned(),
3650                    line_count,
3651                    ExpandExcerptDirection::UpAndDown,
3652                    cx,
3653                );
3654                continue;
3655            }
3656
3657            let excerpt_ids = self.excerpt_ids();
3658            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3659                let buffer_handle = if rng.random() || self.buffers.borrow().is_empty() {
3660                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3661                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3662                    let buffer = buffers.last().unwrap().read(cx);
3663                    log::info!(
3664                        "Creating new buffer {} with text: {:?}",
3665                        buffer.remote_id(),
3666                        buffer.text()
3667                    );
3668                    buffers.last().unwrap().clone()
3669                } else {
3670                    self.buffers
3671                        .borrow()
3672                        .values()
3673                        .choose(rng)
3674                        .unwrap()
3675                        .buffer
3676                        .clone()
3677                };
3678
3679                let buffer = buffer_handle.read(cx);
3680                let buffer_text = buffer.text();
3681                let ranges = (0..rng.random_range(0..5))
3682                    .map(|_| {
3683                        let end_ix =
3684                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3685                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3686                        ExcerptRange::new(start_ix..end_ix)
3687                    })
3688                    .collect::<Vec<_>>();
3689                log::info!(
3690                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3691                    buffer_handle.read(cx).remote_id(),
3692                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3693                    ranges
3694                        .iter()
3695                        .map(|r| &buffer_text[r.context.clone()])
3696                        .collect::<Vec<_>>()
3697                );
3698
3699                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3700                log::info!("Inserted with ids: {:?}", excerpt_id);
3701            } else {
3702                let remove_count = rng.random_range(1..=excerpt_ids.len());
3703                let mut excerpts_to_remove = excerpt_ids
3704                    .choose_multiple(rng, remove_count)
3705                    .cloned()
3706                    .collect::<Vec<_>>();
3707                let snapshot = self.snapshot.borrow();
3708                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3709                drop(snapshot);
3710                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3711                self.remove_excerpts(excerpts_to_remove, cx);
3712            }
3713        }
3714    }
3715
3716    pub fn randomly_mutate(
3717        &mut self,
3718        rng: &mut impl rand::Rng,
3719        mutation_count: usize,
3720        cx: &mut Context<Self>,
3721    ) {
3722        use rand::prelude::*;
3723
3724        if rng.random_bool(0.7) || self.singleton {
3725            let buffer = self
3726                .buffers
3727                .borrow()
3728                .values()
3729                .choose(rng)
3730                .map(|state| state.buffer.clone());
3731
3732            if let Some(buffer) = buffer {
3733                buffer.update(cx, |buffer, cx| {
3734                    if rng.random() {
3735                        buffer.randomly_edit(rng, mutation_count, cx);
3736                    } else {
3737                        buffer.randomly_undo_redo(rng, cx);
3738                    }
3739                });
3740            } else {
3741                self.randomly_edit(rng, mutation_count, cx);
3742            }
3743        } else {
3744            self.randomly_edit_excerpts(rng, mutation_count, cx);
3745        }
3746
3747        self.check_invariants(cx);
3748    }
3749
3750    fn check_invariants(&self, cx: &App) {
3751        self.read(cx).check_invariants();
3752    }
3753}
3754
3755impl EventEmitter<Event> for MultiBuffer {}
3756
3757impl MultiBufferSnapshot {
3758    pub fn text(&self) -> String {
3759        self.chunks(0..self.len(), false)
3760            .map(|chunk| chunk.text)
3761            .collect()
3762    }
3763
3764    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3765        self.reversed_chunks_in_range(0..position.to_offset(self))
3766            .flat_map(|c| c.chars().rev())
3767    }
3768
3769    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks<'_> {
3770        let mut cursor = self.cursor::<usize>();
3771        cursor.seek(&range.end);
3772        let current_chunks = cursor.region().as_ref().map(|region| {
3773            let start_overshoot = range.start.saturating_sub(region.range.start);
3774            let end_overshoot = range.end - region.range.start;
3775            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3776            let start = region.buffer_range.start + start_overshoot;
3777            region.buffer.reversed_chunks_in_range(start..end)
3778        });
3779        ReversedMultiBufferChunks {
3780            cursor,
3781            current_chunks,
3782            start: range.start,
3783            offset: range.end,
3784        }
3785    }
3786
3787    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3788        let offset = position.to_offset(self);
3789        self.text_for_range(offset..self.len())
3790            .flat_map(|chunk| chunk.chars())
3791    }
3792
3793    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3794        self.chunks(range, false).map(|chunk| chunk.text)
3795    }
3796
3797    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3798        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3799            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3800    }
3801
3802    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3803    where
3804        T: ToOffset,
3805    {
3806        let position = position.to_offset(self);
3807        position == self.clip_offset(position, Bias::Left)
3808            && self
3809                .bytes_in_range(position..self.len())
3810                .flatten()
3811                .copied()
3812                .take(needle.len())
3813                .eq(needle.bytes())
3814    }
3815
3816    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3817        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3818    }
3819
3820    pub fn diff_hunks_in_range<T: ToPoint>(
3821        &self,
3822        range: Range<T>,
3823    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3824        let query_range = range.start.to_point(self)..range.end.to_point(self);
3825        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3826            let diff = self.diffs.get(&buffer.remote_id())?;
3827            let buffer_start = buffer.anchor_before(buffer_range.start);
3828            let buffer_end = buffer.anchor_after(buffer_range.end);
3829            Some(
3830                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3831                    .filter_map(|hunk| {
3832                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3833                            return None;
3834                        }
3835                        Some((hunk.range.clone(), hunk))
3836                    }),
3837            )
3838        })
3839        .filter_map(move |(range, hunk, excerpt)| {
3840            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3841            {
3842                return None;
3843            }
3844            let end_row = if range.end.column == 0 {
3845                range.end.row
3846            } else {
3847                range.end.row + 1
3848            };
3849            Some(MultiBufferDiffHunk {
3850                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3851                buffer_id: excerpt.buffer_id,
3852                excerpt_id: excerpt.id,
3853                buffer_range: hunk.buffer_range.clone(),
3854                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3855                secondary_status: hunk.secondary_status,
3856            })
3857        })
3858    }
3859
3860    pub fn excerpt_ids_for_range<T: ToOffset>(
3861        &self,
3862        range: Range<T>,
3863    ) -> impl Iterator<Item = ExcerptId> + '_ {
3864        let range = range.start.to_offset(self)..range.end.to_offset(self);
3865        let mut cursor = self.cursor::<usize>();
3866        cursor.seek(&range.start);
3867        std::iter::from_fn(move || {
3868            let region = cursor.region()?;
3869            if region.range.start >= range.end {
3870                return None;
3871            }
3872            cursor.next_excerpt();
3873            Some(region.excerpt.id)
3874        })
3875    }
3876
3877    pub fn buffer_ids_for_range<T: ToOffset>(
3878        &self,
3879        range: Range<T>,
3880    ) -> impl Iterator<Item = BufferId> + '_ {
3881        let range = range.start.to_offset(self)..range.end.to_offset(self);
3882        let mut cursor = self.cursor::<usize>();
3883        cursor.seek(&range.start);
3884        std::iter::from_fn(move || {
3885            let region = cursor.region()?;
3886            if region.range.start > range.end
3887                || region.range.start == range.end && region.range.start > range.start
3888            {
3889                return None;
3890            }
3891            cursor.next_excerpt();
3892            Some(region.excerpt.buffer_id)
3893        })
3894    }
3895
3896    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3897        &self,
3898        ranges: impl Iterator<Item = Range<T>>,
3899    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3900        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3901    }
3902
3903    pub fn range_to_buffer_ranges<T: ToOffset>(
3904        &self,
3905        range: Range<T>,
3906    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3907        let start = range.start.to_offset(self);
3908        let end = range.end.to_offset(self);
3909
3910        let mut cursor = self.cursor::<usize>();
3911        cursor.seek(&start);
3912
3913        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3914        while let Some(region) = cursor.region() {
3915            if region.range.start > end {
3916                break;
3917            }
3918            if region.is_main_buffer {
3919                let start_overshoot = start.saturating_sub(region.range.start);
3920                let end_overshoot = end.saturating_sub(region.range.start);
3921                let start = region
3922                    .buffer_range
3923                    .end
3924                    .min(region.buffer_range.start + start_overshoot);
3925                let end = region
3926                    .buffer_range
3927                    .end
3928                    .min(region.buffer_range.start + end_overshoot);
3929                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3930                    *excerpt_id == region.excerpt.id && prev_range.end == start
3931                }) {
3932                    prev.1.end = end;
3933                } else {
3934                    result.push((region.buffer, start..end, region.excerpt.id));
3935                }
3936            }
3937            cursor.next();
3938        }
3939        result
3940    }
3941
3942    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3943        &self,
3944        range: Range<T>,
3945    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3946        let start = range.start.to_offset(self);
3947        let end = range.end.to_offset(self);
3948
3949        let mut cursor = self.cursor::<usize>();
3950        cursor.seek(&start);
3951
3952        std::iter::from_fn(move || {
3953            let region = cursor.region()?;
3954            if region.range.start > end {
3955                return None;
3956            }
3957            let start_overshoot = start.saturating_sub(region.range.start);
3958            let end_overshoot = end.saturating_sub(region.range.start);
3959            let start = region
3960                .buffer_range
3961                .end
3962                .min(region.buffer_range.start + start_overshoot);
3963            let end = region
3964                .buffer_range
3965                .end
3966                .min(region.buffer_range.start + end_overshoot);
3967
3968            let region_excerpt_id = region.excerpt.id;
3969            let deleted_hunk_anchor = if region.is_main_buffer {
3970                None
3971            } else {
3972                Some(self.anchor_before(region.range.start))
3973            };
3974            let result = (
3975                region.buffer,
3976                start..end,
3977                region_excerpt_id,
3978                deleted_hunk_anchor,
3979            );
3980            cursor.next();
3981            Some(result)
3982        })
3983    }
3984
3985    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3986    /// coordinates.
3987    ///
3988    /// The given callback will be called for every excerpt intersecting the given range. It will
3989    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3990    /// The callback should return an iterator of metadata items from that buffer, each paired
3991    /// with a buffer range.
3992    ///
3993    /// The returned iterator yields each of these metadata items, paired with its range in
3994    /// multi-buffer coordinates.
3995    fn lift_buffer_metadata<'a, D, M, I>(
3996        &'a self,
3997        query_range: Range<D>,
3998        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
3999    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
4000    where
4001        I: Iterator<Item = (Range<D>, M)> + 'a,
4002        D: TextDimension + Ord + Sub<D, Output = D>,
4003    {
4004        let max_position = D::from_text_summary(&self.text_summary());
4005        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4006        let mut cursor = self.cursor::<D>();
4007
4008        // Find the excerpt and buffer offset where the given range ends.
4009        cursor.seek(&query_range.end);
4010        let mut range_end = None;
4011        while let Some(region) = cursor.region() {
4012            if region.is_main_buffer {
4013                let mut buffer_end = region.buffer_range.start;
4014                let overshoot = if query_range.end > region.range.start {
4015                    query_range.end - region.range.start
4016                } else {
4017                    D::default()
4018                };
4019                buffer_end.add_assign(&overshoot);
4020                range_end = Some((region.excerpt.id, buffer_end));
4021                break;
4022            }
4023            cursor.next();
4024        }
4025
4026        cursor.seek(&query_range.start);
4027
4028        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4029            && region.range.start > D::zero(())
4030        {
4031            cursor.prev()
4032        }
4033
4034        iter::from_fn(move || {
4035            loop {
4036                let excerpt = cursor.excerpt()?;
4037
4038                // If we have already retrieved metadata for this excerpt, continue to use it.
4039                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4040                    .as_mut()
4041                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4042                {
4043                    Some(metadata)
4044                }
4045                // Otherwise, compute the intersection of the input range with the excerpt's range,
4046                // and retrieve the metadata for the resulting range.
4047                else {
4048                    let region = cursor.region()?;
4049                    let mut buffer_start;
4050                    if region.is_main_buffer {
4051                        buffer_start = region.buffer_range.start;
4052                        if query_range.start > region.range.start {
4053                            let overshoot = query_range.start - region.range.start;
4054                            buffer_start.add_assign(&overshoot);
4055                        }
4056                        buffer_start = buffer_start.min(region.buffer_range.end);
4057                    } else {
4058                        buffer_start = cursor.main_buffer_position()?;
4059                    };
4060                    let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4061                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4062                        && excerpt.id == end_excerpt_id
4063                    {
4064                        buffer_end = buffer_end.min(end_buffer_offset);
4065                    }
4066
4067                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4068                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4069                    })
4070                };
4071
4072                // Visit each metadata item.
4073                if let Some((metadata_buffer_range, metadata)) =
4074                    metadata_iter.and_then(Iterator::next)
4075                {
4076                    // Find the multibuffer regions that contain the start and end of
4077                    // the metadata item's range.
4078                    if metadata_buffer_range.start > D::default() {
4079                        while let Some(region) = cursor.region() {
4080                            if region.is_main_buffer
4081                                && (region.buffer_range.end >= metadata_buffer_range.start
4082                                    || cursor.is_at_end_of_excerpt())
4083                            {
4084                                break;
4085                            }
4086                            cursor.next();
4087                        }
4088                    }
4089                    let start_region = cursor.region()?;
4090                    while let Some(region) = cursor.region() {
4091                        if region.is_main_buffer
4092                            && (region.buffer_range.end > metadata_buffer_range.end
4093                                || cursor.is_at_end_of_excerpt())
4094                        {
4095                            break;
4096                        }
4097                        cursor.next();
4098                    }
4099                    let end_region = cursor.region();
4100
4101                    // Convert the metadata item's range into multibuffer coordinates.
4102                    let mut start_position = start_region.range.start;
4103                    let region_buffer_start = start_region.buffer_range.start;
4104                    if start_region.is_main_buffer
4105                        && metadata_buffer_range.start > region_buffer_start
4106                    {
4107                        start_position
4108                            .add_assign(&(metadata_buffer_range.start - region_buffer_start));
4109                        start_position = start_position.min(start_region.range.end);
4110                    }
4111
4112                    let mut end_position = max_position;
4113                    if let Some(end_region) = &end_region {
4114                        end_position = end_region.range.start;
4115                        debug_assert!(end_region.is_main_buffer);
4116                        let region_buffer_start = end_region.buffer_range.start;
4117                        if metadata_buffer_range.end > region_buffer_start {
4118                            end_position
4119                                .add_assign(&(metadata_buffer_range.end - region_buffer_start));
4120                        }
4121                        end_position = end_position.min(end_region.range.end);
4122                    }
4123
4124                    if start_position <= query_range.end && end_position >= query_range.start {
4125                        return Some((start_position..end_position, metadata, excerpt));
4126                    }
4127                }
4128                // When there are no more metadata items for this excerpt, move to the next excerpt.
4129                else {
4130                    current_excerpt_metadata.take();
4131                    if let Some((end_excerpt_id, _)) = range_end
4132                        && excerpt.id == end_excerpt_id
4133                    {
4134                        return None;
4135                    }
4136                    cursor.next_excerpt();
4137                }
4138            }
4139        })
4140    }
4141
4142    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4143        let offset = position.to_offset(self);
4144
4145        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4146        cursor.seek(&DimensionPair {
4147            key: offset,
4148            value: None,
4149        });
4150        cursor.seek_to_start_of_current_excerpt();
4151        let excerpt = cursor.excerpt()?;
4152
4153        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4154        let current_position = self
4155            .anchor_before(offset)
4156            .text_anchor
4157            .to_offset(&excerpt.buffer);
4158        let excerpt_end = excerpt
4159            .buffer
4160            .anchor_before(excerpt_end.min(current_position));
4161
4162        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4163            for hunk in diff.hunks_intersecting_range_rev(
4164                excerpt.range.context.start..excerpt_end,
4165                &excerpt.buffer,
4166            ) {
4167                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4168                if hunk_end >= current_position {
4169                    continue;
4170                }
4171                let start =
4172                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4173                        .to_point(self);
4174                return Some(MultiBufferRow(start.row));
4175            }
4176        }
4177
4178        loop {
4179            cursor.prev_excerpt();
4180            let excerpt = cursor.excerpt()?;
4181
4182            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4183                continue;
4184            };
4185            let mut hunks =
4186                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
4187            let Some(hunk) = hunks.next() else {
4188                continue;
4189            };
4190            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
4191                .to_point(self);
4192            return Some(MultiBufferRow(start.row));
4193        }
4194    }
4195
4196    pub fn has_diff_hunks(&self) -> bool {
4197        self.diffs.values().any(|diff| !diff.is_empty())
4198    }
4199
4200    pub fn is_inside_word<T: ToOffset>(
4201        &self,
4202        position: T,
4203        scope_context: Option<CharScopeContext>,
4204    ) -> bool {
4205        let position = position.to_offset(self);
4206        let classifier = self
4207            .char_classifier_at(position)
4208            .scope_context(scope_context);
4209        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4210        let prev_char_kind = self
4211            .reversed_chars_at(position)
4212            .next()
4213            .map(|c| classifier.kind(c));
4214        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4215    }
4216
4217    pub fn surrounding_word<T: ToOffset>(
4218        &self,
4219        start: T,
4220        scope_context: Option<CharScopeContext>,
4221    ) -> (Range<usize>, Option<CharKind>) {
4222        let mut start = start.to_offset(self);
4223        let mut end = start;
4224        let mut next_chars = self.chars_at(start).peekable();
4225        let mut prev_chars = self.reversed_chars_at(start).peekable();
4226
4227        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4228
4229        let word_kind = cmp::max(
4230            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4231            next_chars.peek().copied().map(|c| classifier.kind(c)),
4232        );
4233
4234        for ch in prev_chars {
4235            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4236                start -= ch.len_utf8();
4237            } else {
4238                break;
4239            }
4240        }
4241
4242        for ch in next_chars {
4243            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4244                end += ch.len_utf8();
4245            } else {
4246                break;
4247            }
4248        }
4249
4250        (start..end, word_kind)
4251    }
4252
4253    pub fn char_kind_before<T: ToOffset>(
4254        &self,
4255        start: T,
4256        scope_context: Option<CharScopeContext>,
4257    ) -> Option<CharKind> {
4258        let start = start.to_offset(self);
4259        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4260        self.reversed_chars_at(start)
4261            .next()
4262            .map(|ch| classifier.kind(ch))
4263    }
4264
4265    pub fn is_singleton(&self) -> bool {
4266        self.singleton
4267    }
4268
4269    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
4270        if self.singleton {
4271            self.excerpts
4272                .iter()
4273                .next()
4274                .map(|e| (&e.id, e.buffer_id, &e.buffer))
4275        } else {
4276            None
4277        }
4278    }
4279
4280    pub fn len(&self) -> usize {
4281        self.diff_transforms.summary().output.len
4282    }
4283
4284    pub fn is_empty(&self) -> bool {
4285        self.excerpts.summary().text.len == 0
4286    }
4287
4288    pub fn widest_line_number(&self) -> u32 {
4289        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4290        self.excerpts.summary().widest_line_number + 1
4291    }
4292
4293    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4294        let range = range.start.to_offset(self)..range.end.to_offset(self);
4295        let mut excerpts = self.cursor::<usize>();
4296        excerpts.seek(&range.start);
4297
4298        let mut chunk;
4299        let mut has_trailing_newline;
4300        let excerpt_bytes;
4301        if let Some(region) = excerpts.region() {
4302            let mut bytes = region.buffer.bytes_in_range(
4303                region.buffer_range.start + range.start - region.range.start
4304                    ..(region.buffer_range.start + range.end - region.range.start)
4305                        .min(region.buffer_range.end),
4306            );
4307            chunk = bytes.next().unwrap_or(&[][..]);
4308            excerpt_bytes = Some(bytes);
4309            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4310            if chunk.is_empty() && has_trailing_newline {
4311                chunk = b"\n";
4312                has_trailing_newline = false;
4313            }
4314        } else {
4315            chunk = &[][..];
4316            excerpt_bytes = None;
4317            has_trailing_newline = false;
4318        };
4319
4320        MultiBufferBytes {
4321            range,
4322            cursor: excerpts,
4323            excerpt_bytes,
4324            has_trailing_newline,
4325            chunk,
4326        }
4327    }
4328
4329    pub fn reversed_bytes_in_range<T: ToOffset>(
4330        &self,
4331        range: Range<T>,
4332    ) -> ReversedMultiBufferBytes<'_> {
4333        let range = range.start.to_offset(self)..range.end.to_offset(self);
4334        let mut chunks = self.reversed_chunks_in_range(range.clone());
4335        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4336        ReversedMultiBufferBytes {
4337            range,
4338            chunks,
4339            chunk,
4340        }
4341    }
4342
4343    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4344        let mut cursor = self.cursor::<Point>();
4345        cursor.seek(&Point::new(start_row.0, 0));
4346        let mut result = MultiBufferRows {
4347            point: Point::new(0, 0),
4348            is_empty: self.excerpts.is_empty(),
4349            is_singleton: self.is_singleton(),
4350            cursor,
4351        };
4352        result.seek(start_row);
4353        result
4354    }
4355
4356    pub fn chunks<T: ToOffset>(
4357        &self,
4358        range: Range<T>,
4359        language_aware: bool,
4360    ) -> MultiBufferChunks<'_> {
4361        let mut chunks = MultiBufferChunks {
4362            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
4363            range: 0..0,
4364            excerpts: self.excerpts.cursor(()),
4365            diff_transforms: self.diff_transforms.cursor(()),
4366            diffs: &self.diffs,
4367            diff_base_chunks: None,
4368            excerpt_chunks: None,
4369            buffer_chunk: None,
4370            language_aware,
4371        };
4372        let range = range.start.to_offset(self)..range.end.to_offset(self);
4373        chunks.seek(range);
4374        chunks
4375    }
4376
4377    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4378        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4379    }
4380
4381    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4382        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4383    }
4384
4385    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4386        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4387    }
4388
4389    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4390        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4391            buffer.clip_point_utf16(Unclipped(point), bias)
4392        })
4393    }
4394
4395    pub fn offset_to_point(&self, offset: usize) -> Point {
4396        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4397    }
4398
4399    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4400        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4401    }
4402
4403    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4404        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4405    }
4406
4407    pub fn point_to_offset(&self, point: Point) -> usize {
4408        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4409    }
4410
4411    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4412        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4413    }
4414
4415    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4416        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4417    }
4418
4419    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4420        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4421    }
4422
4423    fn clip_dimension<D>(
4424        &self,
4425        position: D,
4426        bias: Bias,
4427        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4428    ) -> D
4429    where
4430        D: TextDimension + Ord + Sub<D, Output = D>,
4431    {
4432        let mut cursor = self.cursor();
4433        cursor.seek(&position);
4434        if let Some(region) = cursor.region() {
4435            if position >= region.range.end {
4436                return region.range.end;
4437            }
4438            let overshoot = position - region.range.start;
4439            let mut buffer_position = region.buffer_range.start;
4440            buffer_position.add_assign(&overshoot);
4441            let clipped_buffer_position =
4442                clip_buffer_position(region.buffer, buffer_position, bias);
4443            let mut position = region.range.start;
4444            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4445            position
4446        } else {
4447            D::from_text_summary(&self.text_summary())
4448        }
4449    }
4450
4451    fn convert_dimension<D1, D2>(
4452        &self,
4453        key: D1,
4454        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4455    ) -> D2
4456    where
4457        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4458        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4459    {
4460        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4461        cursor.seek(&DimensionPair { key, value: None });
4462        if let Some(region) = cursor.region() {
4463            if key >= region.range.end.key {
4464                return region.range.end.value.unwrap();
4465            }
4466            let start_key = region.range.start.key;
4467            let start_value = region.range.start.value.unwrap();
4468            let buffer_start_key = region.buffer_range.start.key;
4469            let buffer_start_value = region.buffer_range.start.value.unwrap();
4470            let mut buffer_key = buffer_start_key;
4471            buffer_key.add_assign(&(key - start_key));
4472            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4473            let mut result = start_value;
4474            result.add_assign(&(buffer_value - buffer_start_value));
4475            result
4476        } else {
4477            D2::from_text_summary(&self.text_summary())
4478        }
4479    }
4480
4481    pub fn point_to_buffer_offset<T: ToOffset>(
4482        &self,
4483        point: T,
4484    ) -> Option<(&BufferSnapshot, usize)> {
4485        let offset = point.to_offset(self);
4486        let mut cursor = self.cursor::<usize>();
4487        cursor.seek(&offset);
4488        let region = cursor.region()?;
4489        let overshoot = offset - region.range.start;
4490        let buffer_offset = region.buffer_range.start + overshoot;
4491        if buffer_offset == region.buffer.len() + 1
4492            && region.has_trailing_newline
4493            && !region.is_main_buffer
4494        {
4495            return Some((&cursor.excerpt()?.buffer, cursor.main_buffer_position()?));
4496        } else if buffer_offset > region.buffer.len() {
4497            return None;
4498        }
4499        Some((region.buffer, buffer_offset))
4500    }
4501
4502    pub fn point_to_buffer_point(
4503        &self,
4504        point: Point,
4505    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
4506        let mut cursor = self.cursor::<Point>();
4507        cursor.seek(&point);
4508        let region = cursor.region()?;
4509        let overshoot = point - region.range.start;
4510        let buffer_point = region.buffer_range.start + overshoot;
4511        let excerpt = cursor.excerpt()?;
4512        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
4513            && region.has_trailing_newline
4514            && !region.is_main_buffer
4515        {
4516            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
4517        } else if buffer_point > region.buffer.max_point() {
4518            return None;
4519        }
4520        Some((region.buffer, buffer_point, excerpt.id))
4521    }
4522
4523    pub fn suggested_indents(
4524        &self,
4525        rows: impl IntoIterator<Item = u32>,
4526        cx: &App,
4527    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4528        let mut result = BTreeMap::new();
4529
4530        let mut rows_for_excerpt = Vec::new();
4531        let mut cursor = self.cursor::<Point>();
4532        let mut rows = rows.into_iter().peekable();
4533        let mut prev_row = u32::MAX;
4534        let mut prev_language_indent_size = IndentSize::default();
4535
4536        while let Some(row) = rows.next() {
4537            cursor.seek(&Point::new(row, 0));
4538            let Some(region) = cursor.region() else {
4539                continue;
4540            };
4541
4542            // Retrieve the language and indent size once for each disjoint region being indented.
4543            let single_indent_size = if row.saturating_sub(1) == prev_row {
4544                prev_language_indent_size
4545            } else {
4546                region
4547                    .buffer
4548                    .language_indent_size_at(Point::new(row, 0), cx)
4549            };
4550            prev_language_indent_size = single_indent_size;
4551            prev_row = row;
4552
4553            let start_buffer_row = region.buffer_range.start.row;
4554            let start_multibuffer_row = region.range.start.row;
4555            let end_multibuffer_row = region.range.end.row;
4556
4557            rows_for_excerpt.push(row);
4558            while let Some(next_row) = rows.peek().copied() {
4559                if end_multibuffer_row > next_row {
4560                    rows_for_excerpt.push(next_row);
4561                    rows.next();
4562                } else {
4563                    break;
4564                }
4565            }
4566
4567            let buffer_rows = rows_for_excerpt
4568                .drain(..)
4569                .map(|row| start_buffer_row + row - start_multibuffer_row);
4570            let buffer_indents = region
4571                .buffer
4572                .suggested_indents(buffer_rows, single_indent_size);
4573            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4574                (
4575                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4576                    indent,
4577                )
4578            });
4579            result.extend(multibuffer_indents);
4580        }
4581
4582        result
4583    }
4584
4585    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4586        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4587            let mut size = buffer.indent_size_for_line(range.start.row);
4588            size.len = size
4589                .len
4590                .min(range.end.column)
4591                .saturating_sub(range.start.column);
4592            size
4593        } else {
4594            IndentSize::spaces(0)
4595        }
4596    }
4597
4598    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4599        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4600            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4601        } else {
4602            LineIndent::spaces(0)
4603        }
4604    }
4605
4606    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4607        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4608
4609        if self.language_settings(cx).extend_comment_on_newline
4610            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
4611        {
4612            let delimiters = language_scope.line_comment_prefixes();
4613            for delimiter in delimiters {
4614                if *self
4615                    .chars_at(Point::new(row.0, indent.len() as u32))
4616                    .take(delimiter.chars().count())
4617                    .collect::<String>()
4618                    .as_str()
4619                    == **delimiter
4620                {
4621                    indent.push_str(delimiter);
4622                    break;
4623                }
4624            }
4625        }
4626
4627        indent
4628    }
4629
4630    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4631    where
4632        T: ToOffset,
4633    {
4634        for char in self.reversed_chars_at(position) {
4635            if !char.is_whitespace() {
4636                return false;
4637            }
4638            if char == '\n' {
4639                return true;
4640            }
4641        }
4642        true
4643    }
4644
4645    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4646        while row.0 > 0 {
4647            row.0 -= 1;
4648            if !self.is_line_blank(row) {
4649                return Some(row);
4650            }
4651        }
4652        None
4653    }
4654
4655    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4656        if let Some((_, range)) = self.buffer_line_for_row(row) {
4657            range.end.column - range.start.column
4658        } else {
4659            0
4660        }
4661    }
4662
4663    pub fn buffer_line_for_row(
4664        &self,
4665        row: MultiBufferRow,
4666    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4667        let mut cursor = self.cursor::<Point>();
4668        let point = Point::new(row.0, 0);
4669        cursor.seek(&point);
4670        let region = cursor.region()?;
4671        let overshoot = point.min(region.range.end) - region.range.start;
4672        let buffer_point = region.buffer_range.start + overshoot;
4673        if buffer_point.row > region.buffer_range.end.row {
4674            return None;
4675        }
4676        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4677        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4678            .min(region.buffer_range.end);
4679        Some((region.buffer, line_start..line_end))
4680    }
4681
4682    pub fn max_point(&self) -> Point {
4683        self.text_summary().lines
4684    }
4685
4686    pub fn max_row(&self) -> MultiBufferRow {
4687        MultiBufferRow(self.text_summary().lines.row)
4688    }
4689
4690    pub fn text_summary(&self) -> TextSummary {
4691        self.diff_transforms.summary().output
4692    }
4693
4694    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4695    where
4696        D: TextDimension,
4697        O: ToOffset,
4698    {
4699        let range = range.start.to_offset(self)..range.end.to_offset(self);
4700        let mut cursor = self
4701            .diff_transforms
4702            .cursor::<Dimensions<usize, ExcerptOffset>>(());
4703        cursor.seek(&range.start, Bias::Right);
4704
4705        let Some(first_transform) = cursor.item() else {
4706            return D::from_text_summary(&TextSummary::default());
4707        };
4708
4709        let diff_transform_start = cursor.start().0;
4710        let diff_transform_end = cursor.end().0;
4711        let diff_start = range.start;
4712        let start_overshoot = diff_start - diff_transform_start;
4713        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4714
4715        let mut result = match first_transform {
4716            DiffTransform::BufferContent { .. } => {
4717                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4718                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4719                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4720            }
4721            DiffTransform::DeletedHunk {
4722                buffer_id,
4723                base_text_byte_range,
4724                has_trailing_newline,
4725                ..
4726            } => {
4727                let buffer_start = base_text_byte_range.start + start_overshoot;
4728                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4729                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4730                    panic!("{:?} is in non-existent deleted hunk", range.start)
4731                };
4732
4733                let include_trailing_newline =
4734                    *has_trailing_newline && range.end >= diff_transform_end;
4735                if include_trailing_newline {
4736                    buffer_end -= 1;
4737                }
4738
4739                let mut summary =
4740                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4741
4742                if include_trailing_newline {
4743                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4744                }
4745
4746                summary
4747            }
4748        };
4749        if range.end < diff_transform_end {
4750            return result;
4751        }
4752
4753        cursor.next();
4754        result.add_assign(&D::from_text_summary(
4755            &cursor.summary(&range.end, Bias::Right),
4756        ));
4757
4758        let Some(last_transform) = cursor.item() else {
4759            return result;
4760        };
4761
4762        let overshoot = range.end - cursor.start().0;
4763        let suffix = match last_transform {
4764            DiffTransform::BufferContent { .. } => {
4765                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4766                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4767            }
4768            DiffTransform::DeletedHunk {
4769                base_text_byte_range,
4770                buffer_id,
4771                has_trailing_newline,
4772                ..
4773            } => {
4774                let buffer_end = base_text_byte_range.start + overshoot;
4775                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4776                    panic!("{:?} is in non-existent deleted hunk", range.end)
4777                };
4778
4779                let mut suffix = base_text
4780                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4781                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4782                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4783                }
4784                suffix
4785            }
4786        };
4787
4788        result.add_assign(&suffix);
4789        result
4790    }
4791
4792    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4793    where
4794        D: TextDimension,
4795    {
4796        // let mut range = range.start..range.end;
4797        let mut summary = D::zero(());
4798        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
4799        cursor.seek(&range.start, Bias::Right);
4800        if let Some(excerpt) = cursor.item() {
4801            let mut end_before_newline = cursor.end();
4802            if excerpt.has_trailing_newline {
4803                end_before_newline -= ExcerptOffset::new(1);
4804            }
4805
4806            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4807            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4808            let end_in_excerpt =
4809                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4810            summary.add_assign(
4811                &excerpt
4812                    .buffer
4813                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4814            );
4815
4816            if range.end > end_before_newline {
4817                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4818            }
4819
4820            cursor.next();
4821        }
4822
4823        if range.end > *cursor.start() {
4824            summary.add_assign(
4825                &cursor
4826                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right)
4827                    .0,
4828            );
4829            if let Some(excerpt) = cursor.item() {
4830                range.end = cmp::max(*cursor.start(), range.end);
4831
4832                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4833                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4834                summary.add_assign(
4835                    &excerpt
4836                        .buffer
4837                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4838                );
4839            }
4840        }
4841
4842        summary
4843    }
4844
4845    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4846    where
4847        D: TextDimension + Ord + Sub<D, Output = D>,
4848    {
4849        self.summaries_for_anchors([anchor])[0]
4850    }
4851
4852    fn resolve_summary_for_anchor<D>(
4853        &self,
4854        anchor: &Anchor,
4855        excerpt_position: D,
4856        diff_transforms: &mut Cursor<
4857            DiffTransform,
4858            Dimensions<ExcerptDimension<D>, OutputDimension<D>>,
4859        >,
4860    ) -> D
4861    where
4862        D: TextDimension + Ord + Sub<D, Output = D>,
4863    {
4864        loop {
4865            let transform_end_position = diff_transforms.end().0.0;
4866            let at_transform_end =
4867                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4868            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4869                diff_transforms.next();
4870                continue;
4871            }
4872
4873            let mut position = diff_transforms.start().1.0;
4874            match diff_transforms.item() {
4875                Some(DiffTransform::DeletedHunk {
4876                    buffer_id,
4877                    base_text_byte_range,
4878                    ..
4879                }) => {
4880                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
4881                        && let Some(base_text) =
4882                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4883                        && base_text.can_resolve(diff_base_anchor)
4884                    {
4885                        let base_text_offset = diff_base_anchor.to_offset(base_text);
4886                        if base_text_offset >= base_text_byte_range.start
4887                            && base_text_offset <= base_text_byte_range.end
4888                        {
4889                            let position_in_hunk = base_text.text_summary_for_range::<D, _>(
4890                                base_text_byte_range.start..base_text_offset,
4891                            );
4892                            position.add_assign(&position_in_hunk);
4893                        } else if at_transform_end {
4894                            diff_transforms.next();
4895                            continue;
4896                        }
4897                    }
4898                }
4899                _ => {
4900                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4901                        diff_transforms.next();
4902                        continue;
4903                    }
4904                    let overshoot = excerpt_position - diff_transforms.start().0.0;
4905                    position.add_assign(&overshoot);
4906                }
4907            }
4908
4909            return position;
4910        }
4911    }
4912
4913    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4914        let mut cursor = self
4915            .excerpts
4916            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
4917        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4918
4919        cursor.seek(&Some(locator), Bias::Left);
4920        if cursor.item().is_none() {
4921            cursor.next();
4922        }
4923
4924        let mut position = cursor.start().1;
4925        if let Some(excerpt) = cursor.item()
4926            && excerpt.id == anchor.excerpt_id
4927        {
4928            let excerpt_buffer_start = excerpt
4929                .buffer
4930                .offset_for_anchor(&excerpt.range.context.start);
4931            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4932            let buffer_position = cmp::min(
4933                excerpt_buffer_end,
4934                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4935            );
4936            if buffer_position > excerpt_buffer_start {
4937                position.value += buffer_position - excerpt_buffer_start;
4938            }
4939        }
4940        position
4941    }
4942
4943    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
4944        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
4945            excerpt_id = *replacement;
4946        }
4947        excerpt_id
4948    }
4949
4950    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4951    where
4952        D: TextDimension + Ord + Sub<D, Output = D>,
4953        I: 'a + IntoIterator<Item = &'a Anchor>,
4954    {
4955        let mut anchors = anchors.into_iter().peekable();
4956        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
4957        let mut diff_transforms_cursor = self
4958            .diff_transforms
4959            .cursor::<Dimensions<ExcerptDimension<D>, OutputDimension<D>>>(());
4960        diff_transforms_cursor.next();
4961
4962        let mut summaries = Vec::new();
4963        while let Some(anchor) = anchors.peek() {
4964            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
4965            let excerpt_anchors = iter::from_fn(|| {
4966                let anchor = anchors.peek()?;
4967                if self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id {
4968                    Some(anchors.next().unwrap())
4969                } else {
4970                    None
4971                }
4972            });
4973
4974            let locator = self.excerpt_locator_for_id(excerpt_id);
4975            cursor.seek_forward(locator, Bias::Left);
4976            if cursor.item().is_none() {
4977                cursor.next();
4978            }
4979
4980            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4981            if let Some(excerpt) = cursor.item() {
4982                if excerpt.id != excerpt_id {
4983                    let position = self.resolve_summary_for_anchor(
4984                        &Anchor::min(),
4985                        excerpt_start_position,
4986                        &mut diff_transforms_cursor,
4987                    );
4988                    summaries.extend(excerpt_anchors.map(|_| position));
4989                    continue;
4990                }
4991                let excerpt_buffer_start =
4992                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4993                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4994                for (buffer_summary, anchor) in excerpt
4995                    .buffer
4996                    .summaries_for_anchors_with_payload::<D, _, _>(
4997                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
4998                    )
4999                {
5000                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5001                    let mut position = excerpt_start_position;
5002                    if summary > excerpt_buffer_start {
5003                        position.add_assign(&(summary - excerpt_buffer_start));
5004                    }
5005
5006                    if position > diff_transforms_cursor.start().0.0 {
5007                        diff_transforms_cursor
5008                            .seek_forward(&ExcerptDimension(position), Bias::Left);
5009                    }
5010
5011                    summaries.push(self.resolve_summary_for_anchor(
5012                        anchor,
5013                        position,
5014                        &mut diff_transforms_cursor,
5015                    ));
5016                }
5017            } else {
5018                diff_transforms_cursor
5019                    .seek_forward(&ExcerptDimension(excerpt_start_position), Bias::Left);
5020                let position = self.resolve_summary_for_anchor(
5021                    &Anchor::max(),
5022                    excerpt_start_position,
5023                    &mut diff_transforms_cursor,
5024                );
5025                summaries.extend(excerpt_anchors.map(|_| position));
5026            }
5027        }
5028
5029        summaries
5030    }
5031
5032    pub fn dimensions_from_points<'a, D>(
5033        &'a self,
5034        points: impl 'a + IntoIterator<Item = Point>,
5035    ) -> impl 'a + Iterator<Item = D>
5036    where
5037        D: TextDimension + Sub<D, Output = D>,
5038    {
5039        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
5040        cursor.seek(&DimensionPair {
5041            key: Point::default(),
5042            value: None,
5043        });
5044        let mut points = points.into_iter();
5045        iter::from_fn(move || {
5046            let point = points.next()?;
5047
5048            cursor.seek_forward(&DimensionPair {
5049                key: point,
5050                value: None,
5051            });
5052
5053            if let Some(region) = cursor.region() {
5054                let overshoot = point - region.range.start.key;
5055                let buffer_point = region.buffer_range.start.key + overshoot;
5056                let mut position = region.range.start.value.unwrap();
5057                position.add_assign(
5058                    &region
5059                        .buffer
5060                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
5061                );
5062                if point == region.range.end.key && region.has_trailing_newline {
5063                    position.add_assign(&D::from_text_summary(&TextSummary::newline()));
5064                }
5065                Some(position)
5066            } else {
5067                Some(D::from_text_summary(&self.text_summary()))
5068            }
5069        })
5070    }
5071
5072    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5073    where
5074        I: 'a + IntoIterator<Item = &'a Anchor>,
5075    {
5076        let mut anchors = anchors.into_iter().enumerate().peekable();
5077        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5078        cursor.next();
5079
5080        let mut result = Vec::new();
5081
5082        while let Some((_, anchor)) = anchors.peek() {
5083            let old_excerpt_id = anchor.excerpt_id;
5084
5085            // Find the location where this anchor's excerpt should be.
5086            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5087            cursor.seek_forward(&Some(old_locator), Bias::Left);
5088
5089            if cursor.item().is_none() {
5090                cursor.next();
5091            }
5092
5093            let next_excerpt = cursor.item();
5094            let prev_excerpt = cursor.prev_item();
5095
5096            // Process all of the anchors for this excerpt.
5097            while let Some((_, anchor)) = anchors.peek() {
5098                if anchor.excerpt_id != old_excerpt_id {
5099                    break;
5100                }
5101                let (anchor_ix, anchor) = anchors.next().unwrap();
5102                let mut anchor = *anchor;
5103
5104                // Leave min and max anchors unchanged if invalid or
5105                // if the old excerpt still exists at this location
5106                let mut kept_position = next_excerpt
5107                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5108                    || old_excerpt_id == ExcerptId::max()
5109                    || old_excerpt_id == ExcerptId::min();
5110
5111                // If the old excerpt no longer exists at this location, then attempt to
5112                // find an equivalent position for this anchor in an adjacent excerpt.
5113                if !kept_position {
5114                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5115                        if excerpt.contains(&anchor) {
5116                            anchor.excerpt_id = excerpt.id;
5117                            kept_position = true;
5118                            break;
5119                        }
5120                    }
5121                }
5122
5123                // If there's no adjacent excerpt that contains the anchor's position,
5124                // then report that the anchor has lost its position.
5125                if !kept_position {
5126                    anchor = if let Some(excerpt) = next_excerpt {
5127                        let mut text_anchor = excerpt
5128                            .range
5129                            .context
5130                            .start
5131                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5132                        if text_anchor
5133                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5134                            .is_gt()
5135                        {
5136                            text_anchor = excerpt.range.context.end;
5137                        }
5138                        Anchor {
5139                            buffer_id: Some(excerpt.buffer_id),
5140                            excerpt_id: excerpt.id,
5141                            text_anchor,
5142                            diff_base_anchor: None,
5143                        }
5144                    } else if let Some(excerpt) = prev_excerpt {
5145                        let mut text_anchor = excerpt
5146                            .range
5147                            .context
5148                            .end
5149                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5150                        if text_anchor
5151                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5152                            .is_lt()
5153                        {
5154                            text_anchor = excerpt.range.context.start;
5155                        }
5156                        Anchor {
5157                            buffer_id: Some(excerpt.buffer_id),
5158                            excerpt_id: excerpt.id,
5159                            text_anchor,
5160                            diff_base_anchor: None,
5161                        }
5162                    } else if anchor.text_anchor.bias == Bias::Left {
5163                        Anchor::min()
5164                    } else {
5165                        Anchor::max()
5166                    };
5167                }
5168
5169                result.push((anchor_ix, anchor, kept_position));
5170            }
5171        }
5172        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5173        result
5174    }
5175
5176    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5177        self.anchor_at(position, Bias::Left)
5178    }
5179
5180    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5181        self.anchor_at(position, Bias::Right)
5182    }
5183
5184    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5185        let offset = position.to_offset(self);
5186
5187        // Find the given position in the diff transforms. Determine the corresponding
5188        // offset in the excerpts, and whether the position is within a deleted hunk.
5189        let mut diff_transforms = self
5190            .diff_transforms
5191            .cursor::<Dimensions<usize, ExcerptOffset>>(());
5192        diff_transforms.seek(&offset, Bias::Right);
5193
5194        if offset == diff_transforms.start().0
5195            && bias == Bias::Left
5196            && let Some(prev_item) = diff_transforms.prev_item()
5197            && let DiffTransform::DeletedHunk { .. } = prev_item
5198        {
5199            diff_transforms.prev();
5200        }
5201        let offset_in_transform = offset - diff_transforms.start().0;
5202        let mut excerpt_offset = diff_transforms.start().1;
5203        let mut diff_base_anchor = None;
5204        if let Some(DiffTransform::DeletedHunk {
5205            buffer_id,
5206            base_text_byte_range,
5207            has_trailing_newline,
5208            ..
5209        }) = diff_transforms.item()
5210        {
5211            let diff = self.diffs.get(buffer_id).expect("missing diff");
5212            if offset_in_transform > base_text_byte_range.len() {
5213                debug_assert!(*has_trailing_newline);
5214                bias = Bias::Right;
5215            } else {
5216                diff_base_anchor = Some(
5217                    diff.base_text()
5218                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5219                );
5220                bias = Bias::Left;
5221            }
5222        } else {
5223            excerpt_offset += ExcerptOffset::new(offset_in_transform);
5224        };
5225
5226        let mut excerpts = self
5227            .excerpts
5228            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5229        excerpts.seek(&excerpt_offset, Bias::Right);
5230        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5231            excerpts.prev();
5232        }
5233        if let Some(excerpt) = excerpts.item() {
5234            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
5235            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5236                overshoot -= 1;
5237                bias = Bias::Right;
5238            }
5239
5240            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5241            let text_anchor =
5242                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5243            Anchor {
5244                buffer_id: Some(excerpt.buffer_id),
5245                excerpt_id: excerpt.id,
5246                text_anchor,
5247                diff_base_anchor,
5248            }
5249        } else {
5250            let mut anchor = if excerpt_offset.is_zero() && bias == Bias::Left {
5251                Anchor::min()
5252            } else {
5253                Anchor::max()
5254            };
5255
5256            // TODO this is a hack, because all APIs should be able to handle ExcerptId::min and max.
5257            if let Some((excerpt_id, _, _)) = self.as_singleton() {
5258                anchor.excerpt_id = *excerpt_id;
5259            }
5260            anchor
5261        }
5262    }
5263
5264    /// Returns an anchor for the given excerpt and text anchor,
5265    /// returns None if the excerpt_id is no longer valid.
5266    pub fn anchor_in_excerpt(
5267        &self,
5268        excerpt_id: ExcerptId,
5269        text_anchor: text::Anchor,
5270    ) -> Option<Anchor> {
5271        let excerpt_id = self.latest_excerpt_id(excerpt_id);
5272        let locator = self.excerpt_locator_for_id(excerpt_id);
5273        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5274        cursor.seek(locator, Bias::Left);
5275        if let Some(excerpt) = cursor.item()
5276            && excerpt.id == excerpt_id
5277        {
5278            let text_anchor = excerpt.clip_anchor(text_anchor);
5279            drop(cursor);
5280            return Some(Anchor {
5281                buffer_id: Some(excerpt.buffer_id),
5282                excerpt_id,
5283                text_anchor,
5284                diff_base_anchor: None,
5285            });
5286        }
5287        None
5288    }
5289
5290    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5291        Some(self.excerpt(excerpt_id)?.range.context.clone())
5292    }
5293
5294    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
5295        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
5296            true
5297        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
5298            excerpt.buffer.can_resolve(&anchor.text_anchor)
5299        } else {
5300            false
5301        }
5302    }
5303
5304    pub fn excerpts(
5305        &self,
5306    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
5307        self.excerpts
5308            .iter()
5309            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
5310    }
5311
5312    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<'_, D> {
5313        let excerpts = self.excerpts.cursor(());
5314        let diff_transforms = self.diff_transforms.cursor(());
5315        MultiBufferCursor {
5316            excerpts,
5317            diff_transforms,
5318            diffs: &self.diffs,
5319            cached_region: None,
5320        }
5321    }
5322
5323    pub fn excerpt_before(&self, id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
5324        let start_locator = self.excerpt_locator_for_id(id);
5325        let mut excerpts = self
5326            .excerpts
5327            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<usize>>>(());
5328        excerpts.seek(&Some(start_locator), Bias::Left);
5329        excerpts.prev();
5330
5331        let mut diff_transforms = self.diff_transforms.cursor::<DiffTransforms<usize>>(());
5332        diff_transforms.seek(&excerpts.start().1, Bias::Left);
5333        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
5334            diff_transforms.next();
5335        }
5336
5337        let excerpt = excerpts.item()?;
5338        Some(MultiBufferExcerpt {
5339            excerpt,
5340            offset: diff_transforms.start().output_dimension.0,
5341            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
5342            excerpt_offset: excerpts.start().1.clone(),
5343            diff_transforms,
5344        })
5345    }
5346
5347    pub fn excerpt_boundaries_in_range<R, T>(
5348        &self,
5349        range: R,
5350    ) -> impl Iterator<Item = ExcerptBoundary> + '_
5351    where
5352        R: RangeBounds<T>,
5353        T: ToOffset,
5354    {
5355        let start_offset;
5356        let start = match range.start_bound() {
5357            Bound::Included(start) => {
5358                start_offset = start.to_offset(self);
5359                Bound::Included(start_offset)
5360            }
5361            Bound::Excluded(_) => {
5362                panic!("not supported")
5363            }
5364            Bound::Unbounded => {
5365                start_offset = 0;
5366                Bound::Unbounded
5367            }
5368        };
5369        let end = match range.end_bound() {
5370            Bound::Included(end) => Bound::Included(end.to_offset(self)),
5371            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
5372            Bound::Unbounded => Bound::Unbounded,
5373        };
5374        let bounds = (start, end);
5375
5376        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
5377        cursor.seek(&DimensionPair {
5378            key: start_offset,
5379            value: None,
5380        });
5381
5382        if cursor
5383            .region()
5384            .is_some_and(|region| bounds.contains(&region.range.start.key))
5385        {
5386            cursor.prev_excerpt();
5387        } else {
5388            cursor.seek_to_start_of_current_excerpt();
5389        }
5390        let mut prev_region = cursor.region();
5391
5392        cursor.next_excerpt();
5393
5394        iter::from_fn(move || {
5395            loop {
5396                if self.singleton {
5397                    return None;
5398                }
5399
5400                let next_region = cursor.region()?;
5401                cursor.next_excerpt();
5402                if !bounds.contains(&next_region.range.start.key) {
5403                    prev_region = Some(next_region);
5404                    continue;
5405                }
5406
5407                let next_region_start = next_region.range.start.value.unwrap();
5408                let next_region_end = if let Some(region) = cursor.region() {
5409                    region.range.start.value.unwrap()
5410                } else {
5411                    self.max_point()
5412                };
5413
5414                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5415                    id: region.excerpt.id,
5416                    buffer: region.excerpt.buffer.clone(),
5417                    buffer_id: region.excerpt.buffer_id,
5418                    range: region.excerpt.range.clone(),
5419                    end_row: MultiBufferRow(next_region_start.row),
5420                });
5421
5422                let next = ExcerptInfo {
5423                    id: next_region.excerpt.id,
5424                    buffer: next_region.excerpt.buffer.clone(),
5425                    buffer_id: next_region.excerpt.buffer_id,
5426                    range: next_region.excerpt.range.clone(),
5427                    end_row: if next_region.excerpt.has_trailing_newline {
5428                        MultiBufferRow(next_region_end.row - 1)
5429                    } else {
5430                        MultiBufferRow(next_region_end.row)
5431                    },
5432                };
5433
5434                let row = MultiBufferRow(next_region_start.row);
5435
5436                prev_region = Some(next_region);
5437
5438                return Some(ExcerptBoundary { row, prev, next });
5439            }
5440        })
5441    }
5442
5443    pub fn edit_count(&self) -> usize {
5444        self.edit_count
5445    }
5446
5447    pub fn non_text_state_update_count(&self) -> usize {
5448        self.non_text_state_update_count
5449    }
5450
5451    /// Returns the smallest enclosing bracket ranges containing the given range or
5452    /// None if no brackets contain range or the range is not contained in a single
5453    /// excerpt
5454    ///
5455    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5456    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5457        &self,
5458        range: Range<T>,
5459        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5460    ) -> Option<(Range<usize>, Range<usize>)> {
5461        let range = range.start.to_offset(self)..range.end.to_offset(self);
5462        let mut excerpt = self.excerpt_containing(range.clone())?;
5463        let buffer = excerpt.buffer();
5464        let excerpt_buffer_range = excerpt.buffer_range();
5465
5466        // Filter to ranges contained in the excerpt
5467        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5468            excerpt_buffer_range.contains(&open.start)
5469                && excerpt_buffer_range.contains(&close.end)
5470                && range_filter.is_none_or(|filter| filter(buffer, open, close))
5471        };
5472
5473        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5474            excerpt.map_range_to_buffer(range),
5475            Some(&range_filter),
5476        )?;
5477
5478        Some((
5479            excerpt.map_range_from_buffer(open),
5480            excerpt.map_range_from_buffer(close),
5481        ))
5482    }
5483
5484    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5485    /// not contained in a single excerpt
5486    pub fn enclosing_bracket_ranges<T: ToOffset>(
5487        &self,
5488        range: Range<T>,
5489    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5490        let range = range.start.to_offset(self)..range.end.to_offset(self);
5491        let mut excerpt = self.excerpt_containing(range.clone())?;
5492
5493        Some(
5494            excerpt
5495                .buffer()
5496                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5497                .filter_map(move |pair| {
5498                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5499                        Some((
5500                            excerpt.map_range_from_buffer(pair.open_range),
5501                            excerpt.map_range_from_buffer(pair.close_range),
5502                        ))
5503                    } else {
5504                        None
5505                    }
5506                }),
5507        )
5508    }
5509
5510    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5511    /// not contained in a single excerpt
5512    pub fn text_object_ranges<T: ToOffset>(
5513        &self,
5514        range: Range<T>,
5515        options: TreeSitterOptions,
5516    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5517        let range = range.start.to_offset(self)..range.end.to_offset(self);
5518        self.excerpt_containing(range.clone())
5519            .map(|mut excerpt| {
5520                excerpt
5521                    .buffer()
5522                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5523                    .filter_map(move |(range, text_object)| {
5524                        if excerpt.contains_buffer_range(range.clone()) {
5525                            Some((excerpt.map_range_from_buffer(range), text_object))
5526                        } else {
5527                            None
5528                        }
5529                    })
5530            })
5531            .into_iter()
5532            .flatten()
5533    }
5534
5535    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5536    /// not contained in a single excerpt
5537    pub fn bracket_ranges<T: ToOffset>(
5538        &self,
5539        range: Range<T>,
5540    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5541        let range = range.start.to_offset(self)..range.end.to_offset(self);
5542        let mut excerpt = self.excerpt_containing(range.clone())?;
5543
5544        Some(
5545            excerpt
5546                .buffer()
5547                .bracket_ranges(excerpt.map_range_to_buffer(range))
5548                .filter_map(move |pair| {
5549                    let buffer_range = pair.open_range.start..pair.close_range.end;
5550                    if excerpt.contains_buffer_range(buffer_range) {
5551                        Some((
5552                            excerpt.map_range_from_buffer(pair.open_range),
5553                            excerpt.map_range_from_buffer(pair.close_range),
5554                        ))
5555                    } else {
5556                        None
5557                    }
5558                }),
5559        )
5560    }
5561
5562    pub fn redacted_ranges<'a, T: ToOffset>(
5563        &'a self,
5564        range: Range<T>,
5565        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5566    ) -> impl Iterator<Item = Range<usize>> + 'a {
5567        let range = range.start.to_offset(self)..range.end.to_offset(self);
5568        self.lift_buffer_metadata(range, move |buffer, range| {
5569            if redaction_enabled(buffer.file()) {
5570                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5571            } else {
5572                None
5573            }
5574        })
5575        .map(|(range, _, _)| range)
5576    }
5577
5578    pub fn runnable_ranges(
5579        &self,
5580        range: Range<Anchor>,
5581    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5582        let range = range.start.to_offset(self)..range.end.to_offset(self);
5583        self.lift_buffer_metadata(range, move |buffer, range| {
5584            Some(
5585                buffer
5586                    .runnable_ranges(range.clone())
5587                    .filter(move |runnable| {
5588                        runnable.run_range.start >= range.start
5589                            && runnable.run_range.end < range.end
5590                    })
5591                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5592            )
5593        })
5594        .map(|(run_range, runnable, _)| language::RunnableRange {
5595            run_range,
5596            ..runnable
5597        })
5598    }
5599
5600    pub fn line_indents(
5601        &self,
5602        start_row: MultiBufferRow,
5603        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5604    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5605        let max_point = self.max_point();
5606        let mut cursor = self.cursor::<Point>();
5607        cursor.seek(&Point::new(start_row.0, 0));
5608        iter::from_fn(move || {
5609            let mut region = cursor.region()?;
5610            while !buffer_filter(&region.excerpt.buffer) {
5611                cursor.next();
5612                region = cursor.region()?;
5613            }
5614            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5615            let buffer_start_row =
5616                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5617
5618            let buffer_end_row = if region.is_main_buffer
5619                && (region.has_trailing_newline || region.range.end == max_point)
5620            {
5621                region.buffer_range.end.row
5622            } else {
5623                region.buffer_range.end.row.saturating_sub(1)
5624            };
5625
5626            let line_indents = region
5627                .buffer
5628                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5629            cursor.next();
5630            Some(line_indents.map(move |(buffer_row, indent)| {
5631                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5632                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5633            }))
5634        })
5635        .flatten()
5636    }
5637
5638    pub fn reversed_line_indents(
5639        &self,
5640        end_row: MultiBufferRow,
5641        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5642    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5643        let max_point = self.max_point();
5644        let mut cursor = self.cursor::<Point>();
5645        cursor.seek(&Point::new(end_row.0, 0));
5646        iter::from_fn(move || {
5647            let mut region = cursor.region()?;
5648            while !buffer_filter(&region.excerpt.buffer) {
5649                cursor.prev();
5650                region = cursor.region()?;
5651            }
5652
5653            let buffer_start_row = region.buffer_range.start.row;
5654            let buffer_end_row = if region.is_main_buffer
5655                && (region.has_trailing_newline || region.range.end == max_point)
5656            {
5657                region.buffer_range.end.row + 1
5658            } else {
5659                region.buffer_range.end.row
5660            };
5661
5662            let overshoot = end_row.0 - region.range.start.row;
5663            let buffer_end_row =
5664                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5665
5666            let line_indents = region
5667                .buffer
5668                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5669            cursor.prev();
5670            Some(line_indents.map(move |(buffer_row, indent)| {
5671                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5672                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5673            }))
5674        })
5675        .flatten()
5676    }
5677
5678    pub async fn enclosing_indent(
5679        &self,
5680        mut target_row: MultiBufferRow,
5681    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5682        let max_row = MultiBufferRow(self.max_point().row);
5683        if target_row >= max_row {
5684            return None;
5685        }
5686
5687        let mut target_indent = self.line_indent_for_row(target_row);
5688
5689        // If the current row is at the start of an indented block, we want to return this
5690        // block as the enclosing indent.
5691        if !target_indent.is_line_empty() && target_row < max_row {
5692            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5693            if !next_line_indent.is_line_empty()
5694                && target_indent.raw_len() < next_line_indent.raw_len()
5695            {
5696                target_indent = next_line_indent;
5697                target_row.0 += 1;
5698            }
5699        }
5700
5701        const SEARCH_ROW_LIMIT: u32 = 25000;
5702        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5703        const YIELD_INTERVAL: u32 = 100;
5704
5705        let mut accessed_row_counter = 0;
5706
5707        // If there is a blank line at the current row, search for the next non indented lines
5708        if target_indent.is_line_empty() {
5709            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5710            let end =
5711                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5712
5713            let mut non_empty_line_above = None;
5714            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5715                if row < start {
5716                    break;
5717                }
5718                accessed_row_counter += 1;
5719                if accessed_row_counter == YIELD_INTERVAL {
5720                    accessed_row_counter = 0;
5721                    yield_now().await;
5722                }
5723                if !indent.is_line_empty() {
5724                    non_empty_line_above = Some((row, indent));
5725                    break;
5726                }
5727            }
5728
5729            let mut non_empty_line_below = None;
5730            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5731                if row > end {
5732                    break;
5733                }
5734                accessed_row_counter += 1;
5735                if accessed_row_counter == YIELD_INTERVAL {
5736                    accessed_row_counter = 0;
5737                    yield_now().await;
5738                }
5739                if !indent.is_line_empty() {
5740                    non_empty_line_below = Some((row, indent));
5741                    break;
5742                }
5743            }
5744
5745            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5746                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5747                    if above_indent.raw_len() >= below_indent.raw_len() {
5748                        (above_row, above_indent)
5749                    } else {
5750                        (below_row, below_indent)
5751                    }
5752                }
5753                (Some(above), None) => above,
5754                (None, Some(below)) => below,
5755                _ => return None,
5756            };
5757
5758            target_indent = indent;
5759            target_row = row;
5760        }
5761
5762        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5763        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5764
5765        let mut start_indent = None;
5766        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5767            if row < start {
5768                break;
5769            }
5770            accessed_row_counter += 1;
5771            if accessed_row_counter == YIELD_INTERVAL {
5772                accessed_row_counter = 0;
5773                yield_now().await;
5774            }
5775            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5776                start_indent = Some((row, indent));
5777                break;
5778            }
5779        }
5780        let (start_row, start_indent_size) = start_indent?;
5781
5782        let mut end_indent = (end, None);
5783        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5784            if row > end {
5785                break;
5786            }
5787            accessed_row_counter += 1;
5788            if accessed_row_counter == YIELD_INTERVAL {
5789                accessed_row_counter = 0;
5790                yield_now().await;
5791            }
5792            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5793                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5794                break;
5795            }
5796        }
5797        let (end_row, end_indent_size) = end_indent;
5798
5799        let indent = if let Some(end_indent_size) = end_indent_size {
5800            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5801                start_indent_size
5802            } else {
5803                end_indent_size
5804            }
5805        } else {
5806            start_indent_size
5807        };
5808
5809        Some((start_row..end_row, indent))
5810    }
5811
5812    pub fn indent_guides_in_range<T: ToPoint>(
5813        &self,
5814        range: Range<T>,
5815        ignore_disabled_for_language: bool,
5816        cx: &App,
5817    ) -> impl Iterator<Item = IndentGuide> {
5818        let range = range.start.to_point(self)..range.end.to_point(self);
5819        let start_row = MultiBufferRow(range.start.row);
5820        let end_row = MultiBufferRow(range.end.row);
5821
5822        let mut row_indents = self.line_indents(start_row, |buffer| {
5823            let settings =
5824                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5825            settings.indent_guides.enabled || ignore_disabled_for_language
5826        });
5827
5828        let mut result = Vec::new();
5829        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5830
5831        let mut prev_settings = None;
5832        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5833            if first_row > end_row {
5834                break;
5835            }
5836            let current_depth = indent_stack.len() as u32;
5837
5838            // Avoid retrieving the language settings repeatedly for every buffer row.
5839            if let Some((prev_buffer_id, _)) = &prev_settings
5840                && prev_buffer_id != &buffer.remote_id()
5841            {
5842                prev_settings.take();
5843            }
5844            let settings = &prev_settings
5845                .get_or_insert_with(|| {
5846                    (
5847                        buffer.remote_id(),
5848                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
5849                    )
5850                })
5851                .1;
5852            let tab_size = settings.tab_size.get();
5853
5854            // When encountering empty, continue until found useful line indent
5855            // then add to the indent stack with the depth found
5856            let mut found_indent = false;
5857            let mut last_row = first_row;
5858            if line_indent.is_line_blank() {
5859                while !found_indent {
5860                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5861                        break;
5862                    };
5863                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5864                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5865                        break;
5866                    }
5867
5868                    if new_line_indent.is_line_blank() {
5869                        continue;
5870                    }
5871                    last_row = target_row.min(end_row);
5872                    line_indent = new_line_indent;
5873                    found_indent = true;
5874                    break;
5875                }
5876            } else {
5877                found_indent = true
5878            }
5879
5880            let depth = if found_indent {
5881                line_indent.len(tab_size) / tab_size
5882            } else {
5883                0
5884            };
5885
5886            match depth.cmp(&current_depth) {
5887                cmp::Ordering::Less => {
5888                    for _ in 0..(current_depth - depth) {
5889                        let mut indent = indent_stack.pop().unwrap();
5890                        if last_row != first_row {
5891                            // In this case, we landed on an empty row, had to seek forward,
5892                            // and discovered that the indent we where on is ending.
5893                            // This means that the last display row must
5894                            // be on line that ends this indent range, so we
5895                            // should display the range up to the first non-empty line
5896                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5897                        }
5898
5899                        result.push(indent)
5900                    }
5901                }
5902                cmp::Ordering::Greater => {
5903                    for next_depth in current_depth..depth {
5904                        indent_stack.push(IndentGuide {
5905                            buffer_id: buffer.remote_id(),
5906                            start_row: first_row,
5907                            end_row: last_row,
5908                            depth: next_depth,
5909                            tab_size,
5910                            settings: settings.indent_guides.clone(),
5911                        });
5912                    }
5913                }
5914                _ => {}
5915            }
5916
5917            for indent in indent_stack.iter_mut() {
5918                indent.end_row = last_row;
5919            }
5920        }
5921
5922        result.extend(indent_stack);
5923        result.into_iter()
5924    }
5925
5926    pub fn trailing_excerpt_update_count(&self) -> usize {
5927        self.trailing_excerpt_update_count
5928    }
5929
5930    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5931        self.point_to_buffer_offset(point)
5932            .and_then(|(buffer, _)| buffer.file())
5933    }
5934
5935    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5936        self.point_to_buffer_offset(point)
5937            .and_then(|(buffer, offset)| buffer.language_at(offset))
5938    }
5939
5940    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
5941        self.excerpts
5942            .first()
5943            .map(|excerpt| &excerpt.buffer)
5944            .map(|buffer| {
5945                language_settings(
5946                    buffer.language().map(|language| language.name()),
5947                    buffer.file(),
5948                    cx,
5949                )
5950            })
5951            .unwrap_or_else(move || self.language_settings_at(0, cx))
5952    }
5953
5954    pub fn language_settings_at<'a, T: ToOffset>(
5955        &'a self,
5956        point: T,
5957        cx: &'a App,
5958    ) -> Cow<'a, LanguageSettings> {
5959        let mut language = None;
5960        let mut file = None;
5961        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5962            language = buffer.language_at(offset);
5963            file = buffer.file();
5964        }
5965        language_settings(language.map(|l| l.name()), file, cx)
5966    }
5967
5968    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5969        self.point_to_buffer_offset(point)
5970            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5971    }
5972
5973    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5974        self.point_to_buffer_offset(point)
5975            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5976            .unwrap_or_default()
5977    }
5978
5979    pub fn language_indent_size_at<T: ToOffset>(
5980        &self,
5981        position: T,
5982        cx: &App,
5983    ) -> Option<IndentSize> {
5984        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5985        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5986    }
5987
5988    pub fn is_dirty(&self) -> bool {
5989        self.is_dirty
5990    }
5991
5992    pub fn has_deleted_file(&self) -> bool {
5993        self.has_deleted_file
5994    }
5995
5996    pub fn has_conflict(&self) -> bool {
5997        self.has_conflict
5998    }
5999
6000    pub fn has_diagnostics(&self) -> bool {
6001        self.excerpts
6002            .iter()
6003            .any(|excerpt| excerpt.buffer.has_diagnostics())
6004    }
6005
6006    pub fn diagnostic_group(
6007        &self,
6008        buffer_id: BufferId,
6009        group_id: usize,
6010    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
6011        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, range| {
6012            if buffer.remote_id() != buffer_id {
6013                return None;
6014            };
6015            Some(
6016                buffer
6017                    .diagnostics_in_range(range, false)
6018                    .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
6019                    .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
6020            )
6021        })
6022        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6023    }
6024
6025    pub fn diagnostics_in_range<'a, T>(
6026        &'a self,
6027        range: Range<T>,
6028    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, T>> + 'a
6029    where
6030        T: 'a
6031            + text::ToOffset
6032            + text::FromAnchor
6033            + TextDimension
6034            + Ord
6035            + Sub<T, Output = T>
6036            + fmt::Debug,
6037    {
6038        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6039            Some(
6040                buffer
6041                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6042                    .map(|entry| (entry.range, entry.diagnostic)),
6043            )
6044        })
6045        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6046    }
6047
6048    pub fn diagnostics_with_buffer_ids_in_range<'a, T>(
6049        &'a self,
6050        range: Range<T>,
6051    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, T>)> + 'a
6052    where
6053        T: 'a
6054            + text::ToOffset
6055            + text::FromAnchor
6056            + TextDimension
6057            + Ord
6058            + Sub<T, Output = T>
6059            + fmt::Debug,
6060    {
6061        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
6062            Some(
6063                buffer
6064                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6065                    .map(|entry| (entry.range, entry.diagnostic)),
6066            )
6067        })
6068        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6069    }
6070
6071    pub fn syntax_ancestor<T: ToOffset>(
6072        &self,
6073        range: Range<T>,
6074    ) -> Option<(tree_sitter::Node<'_>, Range<usize>)> {
6075        let range = range.start.to_offset(self)..range.end.to_offset(self);
6076        let mut excerpt = self.excerpt_containing(range.clone())?;
6077        let node = excerpt
6078            .buffer()
6079            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6080        let node_range = node.byte_range();
6081        if !excerpt.contains_buffer_range(node_range.clone()) {
6082            return None;
6083        };
6084        Some((node, excerpt.map_range_from_buffer(node_range)))
6085    }
6086
6087    pub fn syntax_next_sibling<T: ToOffset>(
6088        &self,
6089        range: Range<T>,
6090    ) -> Option<tree_sitter::Node<'_>> {
6091        let range = range.start.to_offset(self)..range.end.to_offset(self);
6092        let mut excerpt = self.excerpt_containing(range.clone())?;
6093        excerpt
6094            .buffer()
6095            .syntax_next_sibling(excerpt.map_range_to_buffer(range))
6096    }
6097
6098    pub fn syntax_prev_sibling<T: ToOffset>(
6099        &self,
6100        range: Range<T>,
6101    ) -> Option<tree_sitter::Node<'_>> {
6102        let range = range.start.to_offset(self)..range.end.to_offset(self);
6103        let mut excerpt = self.excerpt_containing(range.clone())?;
6104        excerpt
6105            .buffer()
6106            .syntax_prev_sibling(excerpt.map_range_to_buffer(range))
6107    }
6108
6109    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6110        let (excerpt_id, _, buffer) = self.as_singleton()?;
6111        let outline = buffer.outline(theme);
6112        Some(Outline::new(
6113            outline
6114                .items
6115                .into_iter()
6116                .flat_map(|item| {
6117                    Some(OutlineItem {
6118                        depth: item.depth,
6119                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
6120                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
6121                        text: item.text,
6122                        highlight_ranges: item.highlight_ranges,
6123                        name_ranges: item.name_ranges,
6124                        body_range: item.body_range.and_then(|body_range| {
6125                            Some(
6126                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
6127                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
6128                            )
6129                        }),
6130                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6131                            Some(
6132                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
6133                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
6134                            )
6135                        }),
6136                    })
6137                })
6138                .collect(),
6139        ))
6140    }
6141
6142    pub fn symbols_containing<T: ToOffset>(
6143        &self,
6144        offset: T,
6145        theme: Option<&SyntaxTheme>,
6146    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6147        let anchor = self.anchor_before(offset);
6148        let excerpt_id = anchor.excerpt_id;
6149        let excerpt = self.excerpt(excerpt_id)?;
6150        let buffer_id = excerpt.buffer_id;
6151        Some((
6152            buffer_id,
6153            excerpt
6154                .buffer
6155                .symbols_containing(anchor.text_anchor, theme)
6156                .into_iter()
6157                .flat_map(|item| {
6158                    Some(OutlineItem {
6159                        depth: item.depth,
6160                        range: Anchor::range_in_buffer(excerpt_id, buffer_id, item.range),
6161                        text: item.text,
6162                        highlight_ranges: item.highlight_ranges,
6163                        name_ranges: item.name_ranges,
6164                        body_range: item.body_range.map(|body_range| {
6165                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6166                        }),
6167                        annotation_range: item.annotation_range.map(|body_range| {
6168                            Anchor::range_in_buffer(excerpt_id, buffer_id, body_range)
6169                        }),
6170                    })
6171                })
6172                .collect(),
6173        ))
6174    }
6175
6176    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6177        if id == ExcerptId::min() {
6178            Locator::min_ref()
6179        } else if id == ExcerptId::max() {
6180            Locator::max_ref()
6181        } else {
6182            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6183            cursor.seek(&id, Bias::Left);
6184            if let Some(entry) = cursor.item()
6185                && entry.id == id
6186            {
6187                return &entry.locator;
6188            }
6189            panic!("invalid excerpt id {id:?}")
6190        }
6191    }
6192
6193    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6194    fn excerpt_locators_for_ids(
6195        &self,
6196        ids: impl IntoIterator<Item = ExcerptId>,
6197    ) -> SmallVec<[Locator; 1]> {
6198        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6199        sorted_ids.sort_unstable();
6200        let mut locators = SmallVec::new();
6201
6202        while sorted_ids.last() == Some(&ExcerptId::max()) {
6203            sorted_ids.pop();
6204            if let Some(mapping) = self.excerpt_ids.last() {
6205                locators.push(mapping.locator.clone());
6206            }
6207        }
6208
6209        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
6210        if sorted_ids.peek() == Some(&ExcerptId::min()) {
6211            sorted_ids.next();
6212            if let Some(mapping) = self.excerpt_ids.first() {
6213                locators.push(mapping.locator.clone());
6214            }
6215        }
6216
6217        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6218        for id in sorted_ids {
6219            if cursor.seek_forward(&id, Bias::Left) {
6220                locators.push(cursor.item().unwrap().locator.clone());
6221            } else {
6222                panic!("invalid excerpt id {:?}", id);
6223            }
6224        }
6225
6226        locators.sort_unstable();
6227        locators
6228    }
6229
6230    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
6231        Some(self.excerpt(excerpt_id)?.buffer_id)
6232    }
6233
6234    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
6235        Some(&self.excerpt(excerpt_id)?.buffer)
6236    }
6237
6238    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
6239        let mut cursor = self
6240            .excerpts
6241            .cursor::<Dimensions<Option<&Locator>, ExcerptDimension<Point>>>(());
6242        let locator = self.excerpt_locator_for_id(excerpt_id);
6243        if cursor.seek(&Some(locator), Bias::Left) {
6244            let start = cursor.start().1.clone();
6245            let end = cursor.end().1;
6246            let mut diff_transforms = self
6247                .diff_transforms
6248                .cursor::<Dimensions<ExcerptDimension<Point>, OutputDimension<Point>>>(());
6249            diff_transforms.seek(&start, Bias::Left);
6250            let overshoot = start.0 - diff_transforms.start().0.0;
6251            let start = diff_transforms.start().1.0 + overshoot;
6252            diff_transforms.seek(&end, Bias::Right);
6253            let overshoot = end.0 - diff_transforms.start().0.0;
6254            let end = diff_transforms.start().1.0 + overshoot;
6255            Some(start..end)
6256        } else {
6257            None
6258        }
6259    }
6260
6261    pub fn buffer_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
6262        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6263        let locator = self.excerpt_locator_for_id(excerpt_id);
6264        if cursor.seek(&Some(locator), Bias::Left)
6265            && let Some(excerpt) = cursor.item()
6266        {
6267            return Some(excerpt.range.context.clone());
6268        }
6269        None
6270    }
6271
6272    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
6273        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
6274        let locator = self.excerpt_locator_for_id(excerpt_id);
6275        cursor.seek(&Some(locator), Bias::Left);
6276        if let Some(excerpt) = cursor.item()
6277            && excerpt.id == excerpt_id
6278        {
6279            return Some(excerpt);
6280        }
6281        None
6282    }
6283
6284    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
6285    pub fn excerpt_containing<T: ToOffset>(
6286        &self,
6287        range: Range<T>,
6288    ) -> Option<MultiBufferExcerpt<'_>> {
6289        let range = range.start.to_offset(self)..range.end.to_offset(self);
6290        let mut cursor = self.cursor::<usize>();
6291        cursor.seek(&range.start);
6292
6293        let start_excerpt = cursor.excerpt()?;
6294        if range.end != range.start {
6295            cursor.seek_forward(&range.end);
6296            if cursor.excerpt()?.id != start_excerpt.id {
6297                return None;
6298            }
6299        }
6300
6301        cursor.seek_to_start_of_current_excerpt();
6302        let region = cursor.region()?;
6303        let offset = region.range.start;
6304        let buffer_offset = start_excerpt.buffer_start_offset();
6305        let excerpt_offset = cursor.excerpts.start().clone();
6306        Some(MultiBufferExcerpt {
6307            diff_transforms: cursor.diff_transforms,
6308            excerpt: start_excerpt,
6309            offset,
6310            buffer_offset,
6311            excerpt_offset,
6312        })
6313    }
6314
6315    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
6316        if let Some(id) = anchor.buffer_id {
6317            return Some(id);
6318        }
6319        let excerpt = self.excerpt_containing(anchor..anchor)?;
6320        Some(excerpt.buffer_id())
6321    }
6322
6323    pub fn selections_in_range<'a>(
6324        &'a self,
6325        range: &'a Range<Anchor>,
6326        include_local: bool,
6327    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
6328        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
6329        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
6330        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
6331        cursor.seek(start_locator, Bias::Left);
6332        cursor
6333            .take_while(move |excerpt| excerpt.locator <= *end_locator)
6334            .flat_map(move |excerpt| {
6335                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
6336                if excerpt.id == range.start.excerpt_id {
6337                    query_range.start = range.start.text_anchor;
6338                }
6339                if excerpt.id == range.end.excerpt_id {
6340                    query_range.end = range.end.text_anchor;
6341                }
6342
6343                excerpt
6344                    .buffer
6345                    .selections_in_range(query_range, include_local)
6346                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
6347                        selections.map(move |selection| {
6348                            let mut start = Anchor {
6349                                buffer_id: Some(excerpt.buffer_id),
6350                                excerpt_id: excerpt.id,
6351                                text_anchor: selection.start,
6352                                diff_base_anchor: None,
6353                            };
6354                            let mut end = Anchor {
6355                                buffer_id: Some(excerpt.buffer_id),
6356                                excerpt_id: excerpt.id,
6357                                text_anchor: selection.end,
6358                                diff_base_anchor: None,
6359                            };
6360                            if range.start.cmp(&start, self).is_gt() {
6361                                start = range.start;
6362                            }
6363                            if range.end.cmp(&end, self).is_lt() {
6364                                end = range.end;
6365                            }
6366
6367                            (
6368                                replica_id,
6369                                line_mode,
6370                                cursor_shape,
6371                                Selection {
6372                                    id: selection.id,
6373                                    start,
6374                                    end,
6375                                    reversed: selection.reversed,
6376                                    goal: selection.goal,
6377                                },
6378                            )
6379                        })
6380                    })
6381            })
6382    }
6383
6384    pub fn show_headers(&self) -> bool {
6385        self.show_headers
6386    }
6387
6388    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
6389        self.diffs.get(&buffer_id)
6390    }
6391
6392    /// Visually annotates a position or range with the `Debug` representation of a value. The
6393    /// callsite of this function is used as a key - previous annotations will be removed.
6394    #[cfg(debug_assertions)]
6395    #[track_caller]
6396    pub fn debug<V, R>(&self, ranges: &R, value: V)
6397    where
6398        R: debug::ToMultiBufferDebugRanges,
6399        V: std::fmt::Debug,
6400    {
6401        self.debug_with_key(std::panic::Location::caller(), ranges, value);
6402    }
6403
6404    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
6405    /// debug annotations with the same key will be removed. The key is also used to determine the
6406    /// annotation's color.
6407    #[cfg(debug_assertions)]
6408    #[track_caller]
6409    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
6410    where
6411        K: std::hash::Hash + 'static,
6412        R: debug::ToMultiBufferDebugRanges,
6413        V: std::fmt::Debug,
6414    {
6415        let text_ranges = ranges
6416            .to_multi_buffer_debug_ranges(self)
6417            .into_iter()
6418            .flat_map(|range| {
6419                self.range_to_buffer_ranges(range).into_iter().map(
6420                    |(buffer, range, _excerpt_id)| {
6421                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
6422                    },
6423                )
6424            })
6425            .collect();
6426        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
6427            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
6428        });
6429    }
6430}
6431
6432#[cfg(any(test, feature = "test-support"))]
6433impl MultiBufferSnapshot {
6434    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
6435        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
6436        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
6437        start..end
6438    }
6439
6440    #[cfg(any(test, feature = "test-support"))]
6441    fn check_invariants(&self) {
6442        let excerpts = self.excerpts.items(());
6443        let excerpt_ids = self.excerpt_ids.items(());
6444
6445        for (ix, excerpt) in excerpts.iter().enumerate() {
6446            if ix == 0 {
6447                if excerpt.locator <= Locator::min() {
6448                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
6449                }
6450            } else if excerpt.locator <= excerpts[ix - 1].locator {
6451                panic!("excerpts are out-of-order: {:?}", excerpts);
6452            }
6453        }
6454
6455        for (ix, entry) in excerpt_ids.iter().enumerate() {
6456            if ix == 0 {
6457                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
6458                    panic!("invalid first excerpt id {:?}", entry.id);
6459                }
6460            } else if entry.id <= excerpt_ids[ix - 1].id {
6461                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
6462            }
6463        }
6464
6465        if self.diff_transforms.summary().input != self.excerpts.summary().text {
6466            panic!(
6467                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
6468                self.excerpts.summary().text.len,
6469                self.diff_transforms.summary().input,
6470                self.diff_transforms.items(()),
6471            );
6472        }
6473
6474        let mut prev_transform: Option<&DiffTransform> = None;
6475        for item in self.diff_transforms.iter() {
6476            if let DiffTransform::BufferContent {
6477                summary,
6478                inserted_hunk_info,
6479            } = item
6480            {
6481                if let Some(DiffTransform::BufferContent {
6482                    inserted_hunk_info: prev_inserted_hunk_info,
6483                    ..
6484                }) = prev_transform
6485                    && *inserted_hunk_info == *prev_inserted_hunk_info
6486                {
6487                    panic!(
6488                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6489                        self.diff_transforms.items(())
6490                    );
6491                }
6492                if summary.len == 0 && !self.is_empty() {
6493                    panic!("empty buffer content transform");
6494                }
6495            }
6496            prev_transform = Some(item);
6497        }
6498    }
6499}
6500
6501impl<'a, D> MultiBufferCursor<'a, D>
6502where
6503    D: TextDimension + Ord + Sub<D, Output = D>,
6504{
6505    fn seek(&mut self, position: &D) {
6506        self.cached_region.take();
6507        self.diff_transforms
6508            .seek(&OutputDimension(*position), Bias::Right);
6509        if self.diff_transforms.item().is_none()
6510            && *position == self.diff_transforms.start().output_dimension.0
6511        {
6512            self.diff_transforms.prev();
6513        }
6514
6515        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6516        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6517            let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6518            excerpt_position.add_assign(&overshoot);
6519        }
6520
6521        self.excerpts
6522            .seek(&ExcerptDimension(excerpt_position), Bias::Right);
6523        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6524            self.excerpts.prev();
6525        }
6526    }
6527
6528    fn seek_forward(&mut self, position: &D) {
6529        self.cached_region.take();
6530        self.diff_transforms
6531            .seek_forward(&OutputDimension(*position), Bias::Right);
6532        if self.diff_transforms.item().is_none()
6533            && *position == self.diff_transforms.start().output_dimension.0
6534        {
6535            self.diff_transforms.prev();
6536        }
6537
6538        let overshoot = *position - self.diff_transforms.start().output_dimension.0;
6539        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension.0;
6540        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6541            excerpt_position.add_assign(&overshoot);
6542        }
6543
6544        self.excerpts
6545            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right);
6546        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6547            self.excerpts.prev();
6548        }
6549    }
6550
6551    fn next_excerpt(&mut self) {
6552        self.excerpts.next();
6553        self.seek_to_start_of_current_excerpt();
6554    }
6555
6556    fn prev_excerpt(&mut self) {
6557        self.excerpts.prev();
6558        self.seek_to_start_of_current_excerpt();
6559    }
6560
6561    fn seek_to_start_of_current_excerpt(&mut self) {
6562        self.cached_region.take();
6563        self.diff_transforms.seek(self.excerpts.start(), Bias::Left);
6564        if self.diff_transforms.end().excerpt_dimension == *self.excerpts.start()
6565            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6566            && self.diff_transforms.next_item().is_some()
6567        {
6568            self.diff_transforms.next();
6569        }
6570    }
6571
6572    fn next(&mut self) {
6573        self.cached_region.take();
6574        match self
6575            .diff_transforms
6576            .end()
6577            .excerpt_dimension
6578            .cmp(&self.excerpts.end())
6579        {
6580            cmp::Ordering::Less => self.diff_transforms.next(),
6581            cmp::Ordering::Greater => self.excerpts.next(),
6582            cmp::Ordering::Equal => {
6583                self.diff_transforms.next();
6584                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6585                    || self.diff_transforms.item().is_none()
6586                {
6587                    self.excerpts.next();
6588                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6589                    self.diff_transforms.item()
6590                    && self
6591                        .excerpts
6592                        .item()
6593                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
6594                {
6595                    self.excerpts.next();
6596                }
6597            }
6598        }
6599    }
6600
6601    fn prev(&mut self) {
6602        self.cached_region.take();
6603        match self
6604            .diff_transforms
6605            .start()
6606            .excerpt_dimension
6607            .cmp(self.excerpts.start())
6608        {
6609            cmp::Ordering::Less => self.excerpts.prev(),
6610            cmp::Ordering::Greater => self.diff_transforms.prev(),
6611            cmp::Ordering::Equal => {
6612                self.diff_transforms.prev();
6613                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
6614                    || self.diff_transforms.item().is_none()
6615                {
6616                    self.excerpts.prev();
6617                }
6618            }
6619        }
6620    }
6621
6622    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6623        if self.cached_region.is_none() {
6624            self.cached_region = self.build_region();
6625        }
6626        self.cached_region.clone()
6627    }
6628
6629    fn is_at_start_of_excerpt(&mut self) -> bool {
6630        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
6631            return false;
6632        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6633            return true;
6634        }
6635
6636        self.diff_transforms.prev();
6637        let prev_transform = self.diff_transforms.item();
6638        self.diff_transforms.next();
6639
6640        prev_transform.is_none_or(|next_transform| {
6641            matches!(next_transform, DiffTransform::BufferContent { .. })
6642        })
6643    }
6644
6645    fn is_at_end_of_excerpt(&mut self) -> bool {
6646        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
6647            return false;
6648        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
6649            || self.diff_transforms.item().is_none()
6650        {
6651            return true;
6652        }
6653
6654        let next_transform = self.diff_transforms.next_item();
6655        next_transform.is_none_or(|next_transform| match next_transform {
6656            DiffTransform::BufferContent { .. } => true,
6657            DiffTransform::DeletedHunk { hunk_info, .. } => self
6658                .excerpts
6659                .item()
6660                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
6661        })
6662    }
6663
6664    fn main_buffer_position(&self) -> Option<D> {
6665        let excerpt = self.excerpts.item()?;
6666        let buffer = &excerpt.buffer;
6667        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6668        let mut buffer_start = buffer_context_start;
6669        let overshoot = self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6670        buffer_start.add_assign(&overshoot);
6671        Some(buffer_start)
6672    }
6673
6674    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6675        let excerpt = self.excerpts.item()?;
6676        match self.diff_transforms.item()? {
6677            DiffTransform::DeletedHunk {
6678                buffer_id,
6679                base_text_byte_range,
6680                has_trailing_newline,
6681                hunk_info,
6682                ..
6683            } => {
6684                let diff = self.diffs.get(buffer_id)?;
6685                let buffer = diff.base_text();
6686                let mut rope_cursor = buffer.as_rope().cursor(0);
6687                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6688                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6689                let mut buffer_end = buffer_start;
6690                buffer_end.add_assign(&buffer_range_len);
6691                let start = self.diff_transforms.start().output_dimension.0;
6692                let end = self.diff_transforms.end().output_dimension.0;
6693                Some(MultiBufferRegion {
6694                    buffer,
6695                    excerpt,
6696                    has_trailing_newline: *has_trailing_newline,
6697                    is_main_buffer: false,
6698                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6699                        hunk_info.hunk_secondary_status,
6700                    )),
6701                    buffer_range: buffer_start..buffer_end,
6702                    range: start..end,
6703                })
6704            }
6705            DiffTransform::BufferContent {
6706                inserted_hunk_info, ..
6707            } => {
6708                let buffer = &excerpt.buffer;
6709                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6710
6711                let mut start = self.diff_transforms.start().output_dimension.0;
6712                let mut buffer_start = buffer_context_start;
6713                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
6714                    let overshoot =
6715                        self.excerpts.start().0 - self.diff_transforms.start().excerpt_dimension.0;
6716                    start.add_assign(&overshoot);
6717                } else {
6718                    let overshoot =
6719                        self.diff_transforms.start().excerpt_dimension.0 - self.excerpts.start().0;
6720                    buffer_start.add_assign(&overshoot);
6721                }
6722
6723                let mut end;
6724                let mut buffer_end;
6725                let has_trailing_newline;
6726                if self.diff_transforms.end().excerpt_dimension.0 < self.excerpts.end().0 {
6727                    let overshoot =
6728                        self.diff_transforms.end().excerpt_dimension.0 - self.excerpts.start().0;
6729                    end = self.diff_transforms.end().output_dimension.0;
6730                    buffer_end = buffer_context_start;
6731                    buffer_end.add_assign(&overshoot);
6732                    has_trailing_newline = false;
6733                } else {
6734                    let overshoot =
6735                        self.excerpts.end().0 - self.diff_transforms.start().excerpt_dimension.0;
6736                    end = self.diff_transforms.start().output_dimension.0;
6737                    end.add_assign(&overshoot);
6738                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6739                    has_trailing_newline = excerpt.has_trailing_newline;
6740                };
6741
6742                Some(MultiBufferRegion {
6743                    buffer,
6744                    excerpt,
6745                    has_trailing_newline,
6746                    is_main_buffer: true,
6747                    diff_hunk_status: inserted_hunk_info
6748                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6749                    buffer_range: buffer_start..buffer_end,
6750                    range: start..end,
6751                })
6752            }
6753        }
6754    }
6755
6756    fn excerpt(&self) -> Option<&'a Excerpt> {
6757        self.excerpts.item()
6758    }
6759}
6760
6761impl History {
6762    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6763        self.transaction_depth += 1;
6764        if self.transaction_depth == 1 {
6765            let id = self.next_transaction_id.tick();
6766            self.undo_stack.push(Transaction {
6767                id,
6768                buffer_transactions: Default::default(),
6769                first_edit_at: now,
6770                last_edit_at: now,
6771                suppress_grouping: false,
6772            });
6773            Some(id)
6774        } else {
6775            None
6776        }
6777    }
6778
6779    fn end_transaction(
6780        &mut self,
6781        now: Instant,
6782        buffer_transactions: HashMap<BufferId, TransactionId>,
6783    ) -> bool {
6784        assert_ne!(self.transaction_depth, 0);
6785        self.transaction_depth -= 1;
6786        if self.transaction_depth == 0 {
6787            if buffer_transactions.is_empty() {
6788                self.undo_stack.pop();
6789                false
6790            } else {
6791                self.redo_stack.clear();
6792                let transaction = self.undo_stack.last_mut().unwrap();
6793                transaction.last_edit_at = now;
6794                for (buffer_id, transaction_id) in buffer_transactions {
6795                    transaction
6796                        .buffer_transactions
6797                        .entry(buffer_id)
6798                        .or_insert(transaction_id);
6799                }
6800                true
6801            }
6802        } else {
6803            false
6804        }
6805    }
6806
6807    fn push_transaction<'a, T>(
6808        &mut self,
6809        buffer_transactions: T,
6810        now: Instant,
6811        cx: &Context<MultiBuffer>,
6812    ) where
6813        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6814    {
6815        assert_eq!(self.transaction_depth, 0);
6816        let transaction = Transaction {
6817            id: self.next_transaction_id.tick(),
6818            buffer_transactions: buffer_transactions
6819                .into_iter()
6820                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6821                .collect(),
6822            first_edit_at: now,
6823            last_edit_at: now,
6824            suppress_grouping: false,
6825        };
6826        if !transaction.buffer_transactions.is_empty() {
6827            self.undo_stack.push(transaction);
6828            self.redo_stack.clear();
6829        }
6830    }
6831
6832    fn finalize_last_transaction(&mut self) {
6833        if let Some(transaction) = self.undo_stack.last_mut() {
6834            transaction.suppress_grouping = true;
6835        }
6836    }
6837
6838    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6839        if let Some(ix) = self
6840            .undo_stack
6841            .iter()
6842            .rposition(|transaction| transaction.id == transaction_id)
6843        {
6844            Some(self.undo_stack.remove(ix))
6845        } else if let Some(ix) = self
6846            .redo_stack
6847            .iter()
6848            .rposition(|transaction| transaction.id == transaction_id)
6849        {
6850            Some(self.redo_stack.remove(ix))
6851        } else {
6852            None
6853        }
6854    }
6855
6856    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6857        self.undo_stack
6858            .iter()
6859            .find(|transaction| transaction.id == transaction_id)
6860            .or_else(|| {
6861                self.redo_stack
6862                    .iter()
6863                    .find(|transaction| transaction.id == transaction_id)
6864            })
6865    }
6866
6867    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6868        self.undo_stack
6869            .iter_mut()
6870            .find(|transaction| transaction.id == transaction_id)
6871            .or_else(|| {
6872                self.redo_stack
6873                    .iter_mut()
6874                    .find(|transaction| transaction.id == transaction_id)
6875            })
6876    }
6877
6878    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6879        assert_eq!(self.transaction_depth, 0);
6880        if let Some(transaction) = self.undo_stack.pop() {
6881            self.redo_stack.push(transaction);
6882            self.redo_stack.last_mut()
6883        } else {
6884            None
6885        }
6886    }
6887
6888    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6889        assert_eq!(self.transaction_depth, 0);
6890        if let Some(transaction) = self.redo_stack.pop() {
6891            self.undo_stack.push(transaction);
6892            self.undo_stack.last_mut()
6893        } else {
6894            None
6895        }
6896    }
6897
6898    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6899        let ix = self
6900            .undo_stack
6901            .iter()
6902            .rposition(|transaction| transaction.id == transaction_id)?;
6903        let transaction = self.undo_stack.remove(ix);
6904        self.redo_stack.push(transaction);
6905        self.redo_stack.last()
6906    }
6907
6908    fn group(&mut self) -> Option<TransactionId> {
6909        let mut count = 0;
6910        let mut transactions = self.undo_stack.iter();
6911        if let Some(mut transaction) = transactions.next_back() {
6912            while let Some(prev_transaction) = transactions.next_back() {
6913                if !prev_transaction.suppress_grouping
6914                    && transaction.first_edit_at - prev_transaction.last_edit_at
6915                        <= self.group_interval
6916                {
6917                    transaction = prev_transaction;
6918                    count += 1;
6919                } else {
6920                    break;
6921                }
6922            }
6923        }
6924        self.group_trailing(count)
6925    }
6926
6927    fn group_until(&mut self, transaction_id: TransactionId) {
6928        let mut count = 0;
6929        for transaction in self.undo_stack.iter().rev() {
6930            if transaction.id == transaction_id {
6931                self.group_trailing(count);
6932                break;
6933            } else if transaction.suppress_grouping {
6934                break;
6935            } else {
6936                count += 1;
6937            }
6938        }
6939    }
6940
6941    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6942        let new_len = self.undo_stack.len() - n;
6943        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6944        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6945            if let Some(transaction) = transactions_to_merge.last() {
6946                last_transaction.last_edit_at = transaction.last_edit_at;
6947            }
6948            for to_merge in transactions_to_merge {
6949                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6950                    last_transaction
6951                        .buffer_transactions
6952                        .entry(*buffer_id)
6953                        .or_insert(*transaction_id);
6954                }
6955            }
6956        }
6957
6958        self.undo_stack.truncate(new_len);
6959        self.undo_stack.last().map(|t| t.id)
6960    }
6961}
6962
6963impl Excerpt {
6964    fn new(
6965        id: ExcerptId,
6966        locator: Locator,
6967        buffer_id: BufferId,
6968        buffer: BufferSnapshot,
6969        range: ExcerptRange<text::Anchor>,
6970        has_trailing_newline: bool,
6971    ) -> Self {
6972        Excerpt {
6973            id,
6974            locator,
6975            max_buffer_row: range.context.end.to_point(&buffer).row,
6976            text_summary: buffer
6977                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6978            buffer_id,
6979            buffer,
6980            range,
6981            has_trailing_newline,
6982        }
6983    }
6984
6985    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
6986        let content_start = self.range.context.start.to_offset(&self.buffer);
6987        let chunks_start = content_start + range.start;
6988        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6989
6990        let footer_height = if self.has_trailing_newline
6991            && range.start <= self.text_summary.len
6992            && range.end > self.text_summary.len
6993        {
6994            1
6995        } else {
6996            0
6997        };
6998
6999        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
7000
7001        ExcerptChunks {
7002            excerpt_id: self.id,
7003            content_chunks,
7004            footer_height,
7005        }
7006    }
7007
7008    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
7009        let content_start = self.range.context.start.to_offset(&self.buffer);
7010        let chunks_start = content_start + range.start;
7011        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7012        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
7013        excerpt_chunks.footer_height = if self.has_trailing_newline
7014            && range.start <= self.text_summary.len
7015            && range.end > self.text_summary.len
7016        {
7017            1
7018        } else {
7019            0
7020        };
7021    }
7022
7023    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
7024        if text_anchor
7025            .cmp(&self.range.context.start, &self.buffer)
7026            .is_lt()
7027        {
7028            self.range.context.start
7029        } else if text_anchor
7030            .cmp(&self.range.context.end, &self.buffer)
7031            .is_gt()
7032        {
7033            self.range.context.end
7034        } else {
7035            text_anchor
7036        }
7037    }
7038
7039    fn contains(&self, anchor: &Anchor) -> bool {
7040        (anchor.buffer_id == None || anchor.buffer_id == Some(self.buffer_id))
7041            && self
7042                .range
7043                .context
7044                .start
7045                .cmp(&anchor.text_anchor, &self.buffer)
7046                .is_le()
7047            && self
7048                .range
7049                .context
7050                .end
7051                .cmp(&anchor.text_anchor, &self.buffer)
7052                .is_ge()
7053    }
7054
7055    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7056    fn buffer_start_offset(&self) -> usize {
7057        self.range.context.start.to_offset(&self.buffer)
7058    }
7059
7060    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7061    fn buffer_end_offset(&self) -> usize {
7062        self.buffer_start_offset() + self.text_summary.len
7063    }
7064}
7065
7066impl<'a> MultiBufferExcerpt<'a> {
7067    pub fn id(&self) -> ExcerptId {
7068        self.excerpt.id
7069    }
7070
7071    pub fn buffer_id(&self) -> BufferId {
7072        self.excerpt.buffer_id
7073    }
7074
7075    pub fn start_anchor(&self) -> Anchor {
7076        Anchor {
7077            buffer_id: Some(self.excerpt.buffer_id),
7078            excerpt_id: self.excerpt.id,
7079            text_anchor: self.excerpt.range.context.start,
7080            diff_base_anchor: None,
7081        }
7082    }
7083
7084    pub fn end_anchor(&self) -> Anchor {
7085        Anchor {
7086            buffer_id: Some(self.excerpt.buffer_id),
7087            excerpt_id: self.excerpt.id,
7088            text_anchor: self.excerpt.range.context.end,
7089            diff_base_anchor: None,
7090        }
7091    }
7092
7093    pub fn buffer(&self) -> &'a BufferSnapshot {
7094        &self.excerpt.buffer
7095    }
7096
7097    pub fn buffer_range(&self) -> Range<usize> {
7098        self.buffer_offset
7099            ..self
7100                .excerpt
7101                .range
7102                .context
7103                .end
7104                .to_offset(&self.excerpt.buffer.text)
7105    }
7106
7107    pub fn start_offset(&self) -> usize {
7108        self.offset
7109    }
7110
7111    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7112    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
7113        self.map_range_to_buffer(offset..offset).start
7114    }
7115
7116    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7117    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
7118        self.diff_transforms
7119            .seek(&OutputDimension(range.start), Bias::Right);
7120        let start = self.map_offset_to_buffer_internal(range.start);
7121        let end = if range.end > range.start {
7122            self.diff_transforms
7123                .seek_forward(&OutputDimension(range.end), Bias::Right);
7124            self.map_offset_to_buffer_internal(range.end)
7125        } else {
7126            start
7127        };
7128        start..end
7129    }
7130
7131    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
7132        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension.clone();
7133        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7134            excerpt_offset.0 += offset - self.diff_transforms.start().output_dimension.0;
7135        };
7136        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
7137        self.buffer_offset + offset_in_excerpt
7138    }
7139
7140    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7141    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
7142        self.map_range_from_buffer(buffer_offset..buffer_offset)
7143            .start
7144    }
7145
7146    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7147    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
7148        if buffer_range.start < self.buffer_offset {
7149            log::warn!(
7150                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7151            );
7152            return buffer_range;
7153        }
7154        let overshoot = buffer_range.start - self.buffer_offset;
7155        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7156        self.diff_transforms.seek(&excerpt_offset, Bias::Right);
7157        if excerpt_offset.0 < self.diff_transforms.start().excerpt_dimension.0 {
7158            log::warn!(
7159                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7160            );
7161            return buffer_range;
7162        }
7163        let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7164        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7165
7166        let end = if buffer_range.end > buffer_range.start {
7167            let overshoot = buffer_range.end - self.buffer_offset;
7168            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
7169            self.diff_transforms
7170                .seek_forward(&excerpt_offset, Bias::Right);
7171            let overshoot = excerpt_offset.0 - self.diff_transforms.start().excerpt_dimension.0;
7172            self.diff_transforms.start().output_dimension.0 + overshoot
7173        } else {
7174            start
7175        };
7176
7177        start..end
7178    }
7179
7180    /// Returns true if the entirety of the given range is in the buffer's excerpt
7181    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
7182        range.start >= self.excerpt.buffer_start_offset()
7183            && range.end <= self.excerpt.buffer_end_offset()
7184    }
7185
7186    pub fn max_buffer_row(&self) -> u32 {
7187        self.excerpt.max_buffer_row
7188    }
7189}
7190
7191impl ExcerptId {
7192    pub fn min() -> Self {
7193        Self(0)
7194    }
7195
7196    pub fn max() -> Self {
7197        Self(u32::MAX)
7198    }
7199
7200    pub fn to_proto(self) -> u64 {
7201        self.0 as _
7202    }
7203
7204    pub fn from_proto(proto: u64) -> Self {
7205        Self(proto as _)
7206    }
7207
7208    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7209        let a = snapshot.excerpt_locator_for_id(*self);
7210        let b = snapshot.excerpt_locator_for_id(*other);
7211        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7212    }
7213}
7214
7215impl From<ExcerptId> for usize {
7216    fn from(val: ExcerptId) -> Self {
7217        val.0 as usize
7218    }
7219}
7220
7221impl fmt::Debug for Excerpt {
7222    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7223        f.debug_struct("Excerpt")
7224            .field("id", &self.id)
7225            .field("locator", &self.locator)
7226            .field("buffer_id", &self.buffer_id)
7227            .field("range", &self.range)
7228            .field("text_summary", &self.text_summary)
7229            .field("has_trailing_newline", &self.has_trailing_newline)
7230            .finish()
7231    }
7232}
7233
7234impl sum_tree::Item for Excerpt {
7235    type Summary = ExcerptSummary;
7236
7237    fn summary(&self, _cx: ()) -> Self::Summary {
7238        let mut text = self.text_summary;
7239        if self.has_trailing_newline {
7240            text += TextSummary::from("\n");
7241        }
7242        ExcerptSummary {
7243            excerpt_id: self.id,
7244            excerpt_locator: self.locator.clone(),
7245            widest_line_number: self.max_buffer_row,
7246            text,
7247        }
7248    }
7249}
7250
7251impl sum_tree::Item for ExcerptIdMapping {
7252    type Summary = ExcerptId;
7253
7254    fn summary(&self, _cx: ()) -> Self::Summary {
7255        self.id
7256    }
7257}
7258
7259impl sum_tree::KeyedItem for ExcerptIdMapping {
7260    type Key = ExcerptId;
7261
7262    fn key(&self) -> Self::Key {
7263        self.id
7264    }
7265}
7266
7267impl DiffTransform {
7268    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7269        match self {
7270            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7271            DiffTransform::BufferContent {
7272                inserted_hunk_info, ..
7273            } => *inserted_hunk_info,
7274        }
7275    }
7276}
7277
7278impl sum_tree::Item for DiffTransform {
7279    type Summary = DiffTransformSummary;
7280
7281    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7282        match self {
7283            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7284                input: *summary,
7285                output: *summary,
7286            },
7287            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7288                input: TextSummary::default(),
7289                output: *summary,
7290            },
7291        }
7292    }
7293}
7294
7295impl DiffTransformSummary {
7296    fn excerpt_len(&self) -> ExcerptOffset {
7297        ExcerptOffset::new(self.input.len)
7298    }
7299}
7300
7301impl sum_tree::ContextLessSummary for DiffTransformSummary {
7302    fn zero() -> Self {
7303        DiffTransformSummary {
7304            input: TextSummary::default(),
7305            output: TextSummary::default(),
7306        }
7307    }
7308
7309    fn add_summary(&mut self, other: &Self) {
7310        self.input += other.input;
7311        self.output += other.output;
7312    }
7313}
7314
7315impl sum_tree::ContextLessSummary for ExcerptId {
7316    fn zero() -> Self {
7317        Self(0)
7318    }
7319
7320    fn add_summary(&mut self, summary: &Self) {
7321        *self = cmp::max(*self, *summary);
7322    }
7323}
7324
7325impl sum_tree::ContextLessSummary for ExcerptSummary {
7326    fn zero() -> Self {
7327        Self::default()
7328    }
7329
7330    fn add_summary(&mut self, summary: &Self) {
7331        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
7332        self.excerpt_locator = summary.excerpt_locator.clone();
7333        Summary::add_summary(&mut self.text, &summary.text, ());
7334        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
7335    }
7336}
7337
7338impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
7339    fn zero(_cx: ()) -> Self {
7340        Default::default()
7341    }
7342
7343    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7344        self.value += summary.text.len;
7345    }
7346}
7347
7348impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
7349    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7350        Ord::cmp(&self.value, &cursor_location.text.len)
7351    }
7352}
7353
7354impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
7355    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
7356        Ord::cmp(&Some(self), cursor_location)
7357    }
7358}
7359
7360impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
7361    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
7362        Ord::cmp(self, &cursor_location.excerpt_locator)
7363    }
7364}
7365
7366impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
7367    fn zero(_cx: ()) -> Self {
7368        Default::default()
7369    }
7370
7371    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7372        self.value += summary.text.lines;
7373    }
7374}
7375
7376impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
7377    for ExcerptDimension<D>
7378{
7379    fn zero(_: ()) -> Self {
7380        ExcerptDimension(D::default())
7381    }
7382
7383    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7384        self.0.add_assign(&D::from_text_summary(&summary.text))
7385    }
7386}
7387
7388impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
7389    fn zero(_cx: ()) -> Self {
7390        Default::default()
7391    }
7392
7393    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7394        *self = Some(&summary.excerpt_locator);
7395    }
7396}
7397
7398impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
7399    fn zero(_cx: ()) -> Self {
7400        Default::default()
7401    }
7402
7403    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
7404        *self = Some(summary.excerpt_id);
7405    }
7406}
7407
7408#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7409struct ExcerptDimension<T>(T);
7410
7411#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
7412struct OutputDimension<T>(T);
7413
7414impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
7415    fn zero(_: ()) -> Self {
7416        ExcerptOffset::new(0)
7417    }
7418
7419    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7420        self.value += summary.input.len;
7421    }
7422}
7423
7424impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
7425    fn zero(_: ()) -> Self {
7426        ExcerptPoint::new(0, 0)
7427    }
7428
7429    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7430        self.value += summary.input.lines;
7431    }
7432}
7433
7434impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
7435    for ExcerptDimension<D>
7436{
7437    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
7438        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
7439    }
7440}
7441
7442impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7443    for ExcerptDimension<D>
7444{
7445    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7446        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
7447    }
7448}
7449
7450impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
7451    fn zero(_: ()) -> Self {
7452        ExcerptDimension(D::default())
7453    }
7454
7455    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7456        self.0.add_assign(&D::from_text_summary(&summary.input))
7457    }
7458}
7459
7460impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransforms<D>>
7461    for OutputDimension<D>
7462{
7463    fn cmp(&self, cursor_location: &DiffTransforms<D>, _: ()) -> cmp::Ordering {
7464        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
7465    }
7466}
7467
7468impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
7469    fn zero(_: ()) -> Self {
7470        OutputDimension(D::default())
7471    }
7472
7473    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7474        self.0.add_assign(&D::from_text_summary(&summary.output))
7475    }
7476}
7477
7478impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
7479    fn zero(_: ()) -> Self {
7480        TextSummary::default()
7481    }
7482
7483    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7484        *self += summary.output
7485    }
7486}
7487
7488impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
7489    fn zero(_: ()) -> Self {
7490        0
7491    }
7492
7493    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7494        *self += summary.output.len
7495    }
7496}
7497
7498impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
7499    fn zero(_: ()) -> Self {
7500        Point::new(0, 0)
7501    }
7502
7503    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
7504        *self += summary.output.lines
7505    }
7506}
7507
7508impl MultiBufferRows<'_> {
7509    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
7510        self.point = Point::new(row, 0);
7511        self.cursor.seek(&self.point);
7512    }
7513}
7514
7515impl Iterator for MultiBufferRows<'_> {
7516    type Item = RowInfo;
7517
7518    fn next(&mut self) -> Option<Self::Item> {
7519        if self.is_empty && self.point.row == 0 {
7520            self.point += Point::new(1, 0);
7521            return Some(RowInfo {
7522                buffer_id: None,
7523                buffer_row: Some(0),
7524                multibuffer_row: Some(MultiBufferRow(0)),
7525                diff_status: None,
7526                expand_info: None,
7527            });
7528        }
7529
7530        let mut region = self.cursor.region()?;
7531        while self.point >= region.range.end {
7532            self.cursor.next();
7533            if let Some(next_region) = self.cursor.region() {
7534                region = next_region;
7535            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
7536                let multibuffer_row = MultiBufferRow(self.point.row);
7537                let last_excerpt = self
7538                    .cursor
7539                    .excerpts
7540                    .item()
7541                    .or(self.cursor.excerpts.prev_item())?;
7542                let last_row = last_excerpt
7543                    .range
7544                    .context
7545                    .end
7546                    .to_point(&last_excerpt.buffer)
7547                    .row;
7548
7549                let first_row = last_excerpt
7550                    .range
7551                    .context
7552                    .start
7553                    .to_point(&last_excerpt.buffer)
7554                    .row;
7555
7556                let expand_info = if self.is_singleton {
7557                    None
7558                } else {
7559                    let needs_expand_up = first_row == last_row
7560                        && last_row > 0
7561                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
7562                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
7563
7564                    if needs_expand_up && needs_expand_down {
7565                        Some(ExpandExcerptDirection::UpAndDown)
7566                    } else if needs_expand_up {
7567                        Some(ExpandExcerptDirection::Up)
7568                    } else if needs_expand_down {
7569                        Some(ExpandExcerptDirection::Down)
7570                    } else {
7571                        None
7572                    }
7573                    .map(|direction| ExpandInfo {
7574                        direction,
7575                        excerpt_id: last_excerpt.id,
7576                    })
7577                };
7578                self.point += Point::new(1, 0);
7579                return Some(RowInfo {
7580                    buffer_id: Some(last_excerpt.buffer_id),
7581                    buffer_row: Some(last_row),
7582                    multibuffer_row: Some(multibuffer_row),
7583                    diff_status: None,
7584                    expand_info,
7585                });
7586            } else {
7587                return None;
7588            };
7589        }
7590
7591        let overshoot = self.point - region.range.start;
7592        let buffer_point = region.buffer_range.start + overshoot;
7593        let expand_info = if self.is_singleton {
7594            None
7595        } else {
7596            let needs_expand_up = self.point.row == region.range.start.row
7597                && self.cursor.is_at_start_of_excerpt()
7598                && buffer_point.row > 0;
7599            let needs_expand_down = (region.excerpt.has_trailing_newline
7600                && self.point.row + 1 == region.range.end.row
7601                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
7602                && self.cursor.is_at_end_of_excerpt()
7603                && buffer_point.row < region.buffer.max_point().row;
7604
7605            if needs_expand_up && needs_expand_down {
7606                Some(ExpandExcerptDirection::UpAndDown)
7607            } else if needs_expand_up {
7608                Some(ExpandExcerptDirection::Up)
7609            } else if needs_expand_down {
7610                Some(ExpandExcerptDirection::Down)
7611            } else {
7612                None
7613            }
7614            .map(|direction| ExpandInfo {
7615                direction,
7616                excerpt_id: region.excerpt.id,
7617            })
7618        };
7619
7620        let result = Some(RowInfo {
7621            buffer_id: Some(region.buffer.remote_id()),
7622            buffer_row: Some(buffer_point.row),
7623            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7624            diff_status: region
7625                .diff_hunk_status
7626                .filter(|_| self.point < region.range.end),
7627            expand_info,
7628        });
7629        self.point += Point::new(1, 0);
7630        result
7631    }
7632}
7633
7634impl<'a> MultiBufferChunks<'a> {
7635    pub fn offset(&self) -> usize {
7636        self.range.start
7637    }
7638
7639    pub fn seek(&mut self, range: Range<usize>) {
7640        self.diff_transforms.seek(&range.end, Bias::Right);
7641        let mut excerpt_end = self.diff_transforms.start().1;
7642        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7643            let overshoot = range.end - self.diff_transforms.start().0;
7644            excerpt_end.value += overshoot;
7645        }
7646
7647        self.diff_transforms.seek(&range.start, Bias::Right);
7648        let mut excerpt_start = self.diff_transforms.start().1;
7649        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7650            let overshoot = range.start - self.diff_transforms.start().0;
7651            excerpt_start.value += overshoot;
7652        }
7653
7654        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7655        self.buffer_chunk.take();
7656        self.range = range;
7657    }
7658
7659    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7660        self.excerpt_offset_range = new_range.clone();
7661        self.excerpts.seek(&new_range.start, Bias::Right);
7662        if let Some(excerpt) = self.excerpts.item() {
7663            let excerpt_start = *self.excerpts.start();
7664            if let Some(excerpt_chunks) = self
7665                .excerpt_chunks
7666                .as_mut()
7667                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7668            {
7669                excerpt.seek_chunks(
7670                    excerpt_chunks,
7671                    (self.excerpt_offset_range.start - excerpt_start).value
7672                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7673                );
7674            } else {
7675                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7676                    (self.excerpt_offset_range.start - excerpt_start).value
7677                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7678                    self.language_aware,
7679                ));
7680            }
7681        } else {
7682            self.excerpt_chunks = None;
7683        }
7684    }
7685
7686    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7687        loop {
7688            if self.excerpt_offset_range.is_empty() {
7689                return None;
7690            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7691                self.excerpt_offset_range.start.value += chunk.text.len();
7692                return Some(chunk);
7693            } else {
7694                self.excerpts.next();
7695                let excerpt = self.excerpts.item()?;
7696                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7697                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7698                    self.language_aware,
7699                ));
7700            }
7701        }
7702    }
7703}
7704
7705impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7706    type Item = &'a str;
7707
7708    fn next(&mut self) -> Option<Self::Item> {
7709        let mut region = self.cursor.region()?;
7710        if self.offset == region.range.start {
7711            self.cursor.prev();
7712            region = self.cursor.region()?;
7713            let start_overshoot = self.start.saturating_sub(region.range.start);
7714            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7715                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7716            ));
7717        }
7718
7719        if self.offset == region.range.end && region.has_trailing_newline {
7720            self.offset -= 1;
7721            Some("\n")
7722        } else {
7723            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7724            self.offset -= chunk.len();
7725            Some(chunk)
7726        }
7727    }
7728}
7729
7730impl<'a> Iterator for MultiBufferChunks<'a> {
7731    type Item = Chunk<'a>;
7732
7733    fn next(&mut self) -> Option<Chunk<'a>> {
7734        if self.range.start >= self.range.end {
7735            return None;
7736        }
7737        if self.range.start == self.diff_transforms.end().0 {
7738            self.diff_transforms.next();
7739        }
7740
7741        let diff_transform_start = self.diff_transforms.start().0;
7742        let diff_transform_end = self.diff_transforms.end().0;
7743        debug_assert!(self.range.start < diff_transform_end);
7744
7745        let diff_transform = self.diff_transforms.item()?;
7746        match diff_transform {
7747            DiffTransform::BufferContent { .. } => {
7748                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7749                    chunk
7750                } else {
7751                    let chunk = self.next_excerpt_chunk().unwrap();
7752                    self.buffer_chunk.insert(chunk)
7753                };
7754
7755                let chunk_end = self.range.start + chunk.text.len();
7756                let diff_transform_end = diff_transform_end.min(self.range.end);
7757
7758                if diff_transform_end < chunk_end {
7759                    let split_idx = diff_transform_end - self.range.start;
7760                    let (before, after) = chunk.text.split_at(split_idx);
7761                    self.range.start = diff_transform_end;
7762                    let mask = (1 << split_idx) - 1;
7763                    let chars = chunk.chars & mask;
7764                    let tabs = chunk.tabs & mask;
7765
7766                    chunk.text = after;
7767                    chunk.chars = chunk.chars >> split_idx;
7768                    chunk.tabs = chunk.tabs >> split_idx;
7769
7770                    Some(Chunk {
7771                        text: before,
7772                        chars,
7773                        tabs,
7774                        ..chunk.clone()
7775                    })
7776                } else {
7777                    self.range.start = chunk_end;
7778                    self.buffer_chunk.take()
7779                }
7780            }
7781            DiffTransform::DeletedHunk {
7782                buffer_id,
7783                base_text_byte_range,
7784                has_trailing_newline,
7785                ..
7786            } => {
7787                let base_text_start =
7788                    base_text_byte_range.start + self.range.start - diff_transform_start;
7789                let base_text_end =
7790                    base_text_byte_range.start + self.range.end - diff_transform_start;
7791                let base_text_end = base_text_end.min(base_text_byte_range.end);
7792
7793                let mut chunks = if let Some((_, mut chunks)) = self
7794                    .diff_base_chunks
7795                    .take()
7796                    .filter(|(id, _)| id == buffer_id)
7797                {
7798                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7799                    {
7800                        chunks.seek(base_text_start..base_text_end);
7801                    }
7802                    chunks
7803                } else {
7804                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
7805                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7806                };
7807
7808                let chunk = if let Some(chunk) = chunks.next() {
7809                    self.range.start += chunk.text.len();
7810                    self.diff_base_chunks = Some((*buffer_id, chunks));
7811                    chunk
7812                } else {
7813                    debug_assert!(has_trailing_newline);
7814                    self.range.start += "\n".len();
7815                    Chunk {
7816                        text: "\n",
7817                        chars: 1u128,
7818                        ..Default::default()
7819                    }
7820                };
7821                Some(chunk)
7822            }
7823        }
7824    }
7825}
7826
7827impl MultiBufferBytes<'_> {
7828    fn consume(&mut self, len: usize) {
7829        self.range.start += len;
7830        self.chunk = &self.chunk[len..];
7831
7832        if !self.range.is_empty() && self.chunk.is_empty() {
7833            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7834                self.chunk = chunk;
7835            } else if self.has_trailing_newline {
7836                self.has_trailing_newline = false;
7837                self.chunk = b"\n";
7838            } else {
7839                self.cursor.next();
7840                if let Some(region) = self.cursor.region() {
7841                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7842                        region.buffer_range.start
7843                            ..(region.buffer_range.start + self.range.end - region.range.start)
7844                                .min(region.buffer_range.end),
7845                    );
7846                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7847                    self.excerpt_bytes = Some(excerpt_bytes);
7848                    self.has_trailing_newline =
7849                        region.has_trailing_newline && self.range.end >= region.range.end;
7850                    if self.chunk.is_empty() && self.has_trailing_newline {
7851                        self.has_trailing_newline = false;
7852                        self.chunk = b"\n";
7853                    }
7854                }
7855            }
7856        }
7857    }
7858}
7859
7860impl<'a> Iterator for MultiBufferBytes<'a> {
7861    type Item = &'a [u8];
7862
7863    fn next(&mut self) -> Option<Self::Item> {
7864        let chunk = self.chunk;
7865        if chunk.is_empty() {
7866            None
7867        } else {
7868            self.consume(chunk.len());
7869            Some(chunk)
7870        }
7871    }
7872}
7873
7874impl io::Read for MultiBufferBytes<'_> {
7875    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7876        let len = cmp::min(buf.len(), self.chunk.len());
7877        buf[..len].copy_from_slice(&self.chunk[..len]);
7878        if len > 0 {
7879            self.consume(len);
7880        }
7881        Ok(len)
7882    }
7883}
7884
7885impl io::Read for ReversedMultiBufferBytes<'_> {
7886    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7887        let len = cmp::min(buf.len(), self.chunk.len());
7888        buf[..len].copy_from_slice(&self.chunk[..len]);
7889        buf[..len].reverse();
7890        if len > 0 {
7891            self.range.end -= len;
7892            self.chunk = &self.chunk[..self.chunk.len() - len];
7893            if !self.range.is_empty()
7894                && self.chunk.is_empty()
7895                && let Some(chunk) = self.chunks.next()
7896            {
7897                self.chunk = chunk.as_bytes();
7898            }
7899        }
7900        Ok(len)
7901    }
7902}
7903
7904impl<'a> Iterator for ExcerptChunks<'a> {
7905    type Item = Chunk<'a>;
7906
7907    fn next(&mut self) -> Option<Self::Item> {
7908        if let Some(chunk) = self.content_chunks.next() {
7909            return Some(chunk);
7910        }
7911
7912        if self.footer_height > 0 {
7913            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7914            let chars = (1 << self.footer_height) - 1;
7915            self.footer_height = 0;
7916            return Some(Chunk {
7917                text,
7918                chars,
7919                ..Default::default()
7920            });
7921        }
7922
7923        None
7924    }
7925}
7926
7927impl ToOffset for Point {
7928    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7929        snapshot.point_to_offset(*self)
7930    }
7931}
7932
7933impl ToOffset for usize {
7934    #[track_caller]
7935    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7936        assert!(
7937            *self <= snapshot.len(),
7938            "offset {} is greater than the snapshot.len() {}",
7939            *self,
7940            snapshot.len(),
7941        );
7942        *self
7943    }
7944}
7945
7946impl ToOffset for OffsetUtf16 {
7947    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7948        snapshot.offset_utf16_to_offset(*self)
7949    }
7950}
7951
7952impl ToOffset for PointUtf16 {
7953    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7954        snapshot.point_utf16_to_offset(*self)
7955    }
7956}
7957
7958impl ToOffsetUtf16 for OffsetUtf16 {
7959    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7960        *self
7961    }
7962}
7963
7964impl ToOffsetUtf16 for usize {
7965    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7966        snapshot.offset_to_offset_utf16(*self)
7967    }
7968}
7969
7970impl ToPoint for usize {
7971    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7972        snapshot.offset_to_point(*self)
7973    }
7974}
7975
7976impl ToPoint for Point {
7977    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7978        *self
7979    }
7980}
7981
7982impl ToPointUtf16 for usize {
7983    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7984        snapshot.offset_to_point_utf16(*self)
7985    }
7986}
7987
7988impl ToPointUtf16 for Point {
7989    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7990        snapshot.point_to_point_utf16(*self)
7991    }
7992}
7993
7994impl ToPointUtf16 for PointUtf16 {
7995    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7996        *self
7997    }
7998}
7999
8000impl From<ExcerptId> for EntityId {
8001    fn from(id: ExcerptId) -> Self {
8002        EntityId::from(id.0 as u64)
8003    }
8004}
8005
8006#[cfg(debug_assertions)]
8007pub mod debug {
8008    use super::*;
8009
8010    pub trait ToMultiBufferDebugRanges {
8011        fn to_multi_buffer_debug_ranges(&self, snapshot: &MultiBufferSnapshot)
8012        -> Vec<Range<usize>>;
8013    }
8014
8015    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
8016        fn to_multi_buffer_debug_ranges(
8017            &self,
8018            snapshot: &MultiBufferSnapshot,
8019        ) -> Vec<Range<usize>> {
8020            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
8021        }
8022    }
8023
8024    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
8025        fn to_multi_buffer_debug_ranges(
8026            &self,
8027            snapshot: &MultiBufferSnapshot,
8028        ) -> Vec<Range<usize>> {
8029            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
8030                .to_multi_buffer_debug_ranges(snapshot)
8031        }
8032    }
8033
8034    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
8035        fn to_multi_buffer_debug_ranges(
8036            &self,
8037            snapshot: &MultiBufferSnapshot,
8038        ) -> Vec<Range<usize>> {
8039            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8040        }
8041    }
8042
8043    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8044        fn to_multi_buffer_debug_ranges(
8045            &self,
8046            snapshot: &MultiBufferSnapshot,
8047        ) -> Vec<Range<usize>> {
8048            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8049        }
8050    }
8051
8052    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8053        fn to_multi_buffer_debug_ranges(
8054            &self,
8055            snapshot: &MultiBufferSnapshot,
8056        ) -> Vec<Range<usize>> {
8057            self.iter()
8058                .map(|item| {
8059                    let offset = item.to_offset(snapshot);
8060                    offset..offset
8061                })
8062                .collect()
8063        }
8064    }
8065
8066    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8067        fn to_multi_buffer_debug_ranges(
8068            &self,
8069            snapshot: &MultiBufferSnapshot,
8070        ) -> Vec<Range<usize>> {
8071            self.iter()
8072                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8073                .collect()
8074        }
8075    }
8076}