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