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