multi_buffer.rs

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