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