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 settings_at<'a, T: ToOffset>(&self, point: T, cx: &'a App) -> Cow<'a, LanguageSettings> {
2317        let mut language = None;
2318        let mut file = None;
2319        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2320            let buffer = buffer.read(cx);
2321            language = buffer.language_at(offset);
2322            file = buffer.file();
2323        }
2324        language_settings(language.map(|l| l.name()), file, cx)
2325    }
2326
2327    pub fn for_each_buffer(&self, mut f: impl FnMut(&Entity<Buffer>)) {
2328        self.buffers
2329            .borrow()
2330            .values()
2331            .for_each(|state| f(&state.buffer))
2332    }
2333
2334    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2335        if let Some(title) = self.title.as_ref() {
2336            return title.into();
2337        }
2338
2339        if let Some(buffer) = self.as_singleton() {
2340            if let Some(file) = buffer.read(cx).file() {
2341                return file.file_name(cx).to_string_lossy();
2342            }
2343        }
2344
2345        "untitled".into()
2346    }
2347
2348    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2349        self.title = Some(title);
2350        cx.notify();
2351    }
2352
2353    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2354    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2355        for buffer_state in self.buffers.borrow().values() {
2356            buffer_state
2357                .buffer
2358                .update(cx, |buffer, _cx| buffer.refresh_preview());
2359        }
2360    }
2361
2362    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2363    pub fn preserve_preview(&self, cx: &App) -> bool {
2364        self.buffers
2365            .borrow()
2366            .values()
2367            .all(|state| state.buffer.read(cx).preserve_preview())
2368    }
2369
2370    #[cfg(any(test, feature = "test-support"))]
2371    pub fn is_parsing(&self, cx: &App) -> bool {
2372        self.as_singleton().unwrap().read(cx).is_parsing()
2373    }
2374
2375    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2376        let buffer_id = diff.read(cx).buffer_id;
2377        self.buffer_diff_changed(diff.clone(), text::Anchor::MIN..text::Anchor::MAX, cx);
2378        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2379    }
2380
2381    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2382        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2383    }
2384
2385    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2386        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2387    }
2388
2389    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2390        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2391    }
2392
2393    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2394        self.snapshot.borrow_mut().all_diff_hunks_expanded = true;
2395        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2396    }
2397
2398    pub fn all_diff_hunks_expanded(&self) -> bool {
2399        self.snapshot.borrow().all_diff_hunks_expanded
2400    }
2401
2402    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2403        self.read(cx)
2404            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2405            .nth(1)
2406            .is_some()
2407    }
2408
2409    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2410        let snapshot = self.read(cx);
2411        let mut cursor = snapshot.diff_transforms.cursor::<usize>(&());
2412        let offset_range = range.to_offset(&snapshot);
2413        cursor.seek(&offset_range.start, Bias::Left, &());
2414        while let Some(item) = cursor.item() {
2415            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2416                break;
2417            }
2418            if item.hunk_info().is_some() {
2419                return true;
2420            }
2421            cursor.next(&());
2422        }
2423        false
2424    }
2425
2426    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2427        let snapshot = self.read(cx);
2428        let mut cursor = snapshot.diff_transforms.cursor::<usize>(&());
2429        for range in ranges {
2430            let range = range.to_point(&snapshot);
2431            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2432            let end = snapshot.point_to_offset(Point::new(range.end.row + 1, 0));
2433            let start = start.saturating_sub(1);
2434            let end = snapshot.len().min(end + 1);
2435            cursor.seek(&start, Bias::Right, &());
2436            while let Some(item) = cursor.item() {
2437                if *cursor.start() >= end {
2438                    break;
2439                }
2440                if item.hunk_info().is_some() {
2441                    return true;
2442                }
2443                cursor.next(&());
2444            }
2445        }
2446        false
2447    }
2448
2449    pub fn expand_or_collapse_diff_hunks_inner(
2450        &mut self,
2451        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2452        expand: bool,
2453        cx: &mut Context<Self>,
2454    ) {
2455        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2456            return;
2457        }
2458        self.sync(cx);
2459        let mut snapshot = self.snapshot.borrow_mut();
2460        let mut excerpt_edits = Vec::new();
2461        for (range, end_excerpt_id) in ranges {
2462            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2463                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2464                    continue;
2465                }
2466                let start = Anchor::in_buffer(
2467                    diff_hunk.excerpt_id,
2468                    diff_hunk.buffer_id,
2469                    diff_hunk.buffer_range.start,
2470                );
2471                let end = Anchor::in_buffer(
2472                    diff_hunk.excerpt_id,
2473                    diff_hunk.buffer_id,
2474                    diff_hunk.buffer_range.end,
2475                );
2476                let start = snapshot.excerpt_offset_for_anchor(&start);
2477                let end = snapshot.excerpt_offset_for_anchor(&end);
2478                excerpt_edits.push(text::Edit {
2479                    old: start..end,
2480                    new: start..end,
2481                });
2482            }
2483        }
2484
2485        self.sync_diff_transforms(
2486            &mut snapshot,
2487            excerpt_edits,
2488            DiffChangeKind::ExpandOrCollapseHunks { expand },
2489        );
2490        cx.emit(Event::DiffHunksToggled);
2491        cx.emit(Event::Edited {
2492            singleton_buffer_edited: false,
2493            edited_buffer: None,
2494        });
2495    }
2496
2497    pub fn expand_or_collapse_diff_hunks(
2498        &mut self,
2499        ranges: Vec<Range<Anchor>>,
2500        expand: bool,
2501        cx: &mut Context<Self>,
2502    ) {
2503        let snapshot = self.snapshot.borrow().clone();
2504        let ranges = ranges.iter().map(move |range| {
2505            let end_excerpt_id = range.end.excerpt_id;
2506            let range = range.to_point(&snapshot);
2507            let mut peek_end = range.end;
2508            if range.end.row < snapshot.max_row().0 {
2509                peek_end = Point::new(range.end.row + 1, 0);
2510            };
2511            (range.start..peek_end, end_excerpt_id)
2512        });
2513        self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2514    }
2515
2516    pub fn resize_excerpt(
2517        &mut self,
2518        id: ExcerptId,
2519        range: Range<text::Anchor>,
2520        cx: &mut Context<Self>,
2521    ) {
2522        self.sync(cx);
2523
2524        let mut snapshot = self.snapshot.borrow_mut();
2525        let locator = snapshot.excerpt_locator_for_id(id);
2526        let mut new_excerpts = SumTree::default();
2527        let mut cursor = snapshot
2528            .excerpts
2529            .cursor::<(Option<&Locator>, ExcerptOffset)>(&());
2530        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2531
2532        let prefix = cursor.slice(&Some(locator), Bias::Left, &());
2533        new_excerpts.append(prefix, &());
2534
2535        let mut excerpt = cursor.item().unwrap().clone();
2536        let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2537
2538        excerpt.range.context.start = range.start;
2539        excerpt.range.context.end = range.end;
2540        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2541
2542        excerpt.text_summary = excerpt
2543            .buffer
2544            .text_summary_for_range(excerpt.range.context.clone());
2545
2546        let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2547        let old_start_offset = cursor.start().1;
2548        let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2549        let edit = Edit {
2550            old: old_start_offset..old_start_offset + old_text_len,
2551            new: new_start_offset..new_start_offset + new_text_len,
2552        };
2553
2554        if let Some(last_edit) = edits.last_mut() {
2555            if last_edit.old.end == edit.old.start {
2556                last_edit.old.end = edit.old.end;
2557                last_edit.new.end = edit.new.end;
2558            } else {
2559                edits.push(edit);
2560            }
2561        } else {
2562            edits.push(edit);
2563        }
2564
2565        new_excerpts.push(excerpt, &());
2566
2567        cursor.next(&());
2568
2569        new_excerpts.append(cursor.suffix(&()), &());
2570
2571        drop(cursor);
2572        snapshot.excerpts = new_excerpts;
2573
2574        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2575        cx.emit(Event::Edited {
2576            singleton_buffer_edited: false,
2577            edited_buffer: None,
2578        });
2579        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2580        cx.notify();
2581    }
2582
2583    pub fn expand_excerpts(
2584        &mut self,
2585        ids: impl IntoIterator<Item = ExcerptId>,
2586        line_count: u32,
2587        direction: ExpandExcerptDirection,
2588        cx: &mut Context<Self>,
2589    ) {
2590        if line_count == 0 {
2591            return;
2592        }
2593        self.sync(cx);
2594        let mut snapshot = self.snapshot.borrow_mut();
2595
2596        let ids = ids.into_iter().collect::<Vec<_>>();
2597        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2598        let mut new_excerpts = SumTree::default();
2599        let mut cursor = snapshot
2600            .excerpts
2601            .cursor::<(Option<&Locator>, ExcerptOffset)>(&());
2602        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2603
2604        for locator in &locators {
2605            let prefix = cursor.slice(&Some(locator), Bias::Left, &());
2606            new_excerpts.append(prefix, &());
2607
2608            let mut excerpt = cursor.item().unwrap().clone();
2609            let old_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2610
2611            let up_line_count = if direction.should_expand_up() {
2612                line_count
2613            } else {
2614                0
2615            };
2616
2617            let start_row = excerpt
2618                .range
2619                .context
2620                .start
2621                .to_point(&excerpt.buffer)
2622                .row
2623                .saturating_sub(up_line_count);
2624            let start_point = Point::new(start_row, 0);
2625            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
2626
2627            let down_line_count = if direction.should_expand_down() {
2628                line_count
2629            } else {
2630                0
2631            };
2632
2633            let mut end_point = excerpt.buffer.clip_point(
2634                excerpt.range.context.end.to_point(&excerpt.buffer)
2635                    + Point::new(down_line_count, 0),
2636                Bias::Left,
2637            );
2638            end_point.column = excerpt.buffer.line_len(end_point.row);
2639            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
2640            excerpt.max_buffer_row = end_point.row;
2641
2642            excerpt.text_summary = excerpt
2643                .buffer
2644                .text_summary_for_range(excerpt.range.context.clone());
2645
2646            let new_start_offset = ExcerptOffset::new(new_excerpts.summary().text.len);
2647            let old_start_offset = cursor.start().1;
2648            let new_text_len = ExcerptOffset::new(excerpt.text_summary.len);
2649            let edit = Edit {
2650                old: old_start_offset..old_start_offset + old_text_len,
2651                new: new_start_offset..new_start_offset + new_text_len,
2652            };
2653
2654            if let Some(last_edit) = edits.last_mut() {
2655                if last_edit.old.end == edit.old.start {
2656                    last_edit.old.end = edit.old.end;
2657                    last_edit.new.end = edit.new.end;
2658                } else {
2659                    edits.push(edit);
2660                }
2661            } else {
2662                edits.push(edit);
2663            }
2664
2665            new_excerpts.push(excerpt, &());
2666
2667            cursor.next(&());
2668        }
2669
2670        new_excerpts.append(cursor.suffix(&()), &());
2671
2672        drop(cursor);
2673        snapshot.excerpts = new_excerpts;
2674
2675        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2676        cx.emit(Event::Edited {
2677            singleton_buffer_edited: false,
2678            edited_buffer: None,
2679        });
2680        cx.emit(Event::ExcerptsExpanded { ids });
2681        cx.notify();
2682    }
2683
2684    fn sync(&self, cx: &App) {
2685        let mut snapshot = self.snapshot.borrow_mut();
2686        let mut excerpts_to_edit = Vec::new();
2687        let mut non_text_state_updated = false;
2688        let mut is_dirty = false;
2689        let mut has_deleted_file = false;
2690        let mut has_conflict = false;
2691        let mut edited = false;
2692        let mut buffers = self.buffers.borrow_mut();
2693        for buffer_state in buffers.values_mut() {
2694            let buffer = buffer_state.buffer.read(cx);
2695            let version = buffer.version();
2696            let non_text_state_update_count = buffer.non_text_state_update_count();
2697
2698            let buffer_edited = version.changed_since(&buffer_state.last_version);
2699            let buffer_non_text_state_updated =
2700                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
2701            if buffer_edited || buffer_non_text_state_updated {
2702                buffer_state.last_version = version;
2703                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
2704                excerpts_to_edit.extend(
2705                    buffer_state
2706                        .excerpts
2707                        .iter()
2708                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
2709                );
2710            }
2711
2712            edited |= buffer_edited;
2713            non_text_state_updated |= buffer_non_text_state_updated;
2714            is_dirty |= buffer.is_dirty();
2715            has_deleted_file |= buffer
2716                .file()
2717                .map_or(false, |file| file.disk_state() == DiskState::Deleted);
2718            has_conflict |= buffer.has_conflict();
2719        }
2720        if edited {
2721            snapshot.edit_count += 1;
2722        }
2723        if non_text_state_updated {
2724            snapshot.non_text_state_update_count += 1;
2725        }
2726        snapshot.is_dirty = is_dirty;
2727        snapshot.has_deleted_file = has_deleted_file;
2728        snapshot.has_conflict = has_conflict;
2729
2730        for (id, diff) in self.diffs.iter() {
2731            if snapshot.diffs.get(&id).is_none() {
2732                snapshot.diffs.insert(*id, diff.diff.read(cx).snapshot(cx));
2733            }
2734        }
2735
2736        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
2737
2738        let mut edits = Vec::new();
2739        let mut new_excerpts = SumTree::default();
2740        let mut cursor = snapshot
2741            .excerpts
2742            .cursor::<(Option<&Locator>, ExcerptOffset)>(&());
2743
2744        for (locator, buffer, buffer_edited) in excerpts_to_edit {
2745            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
2746            let old_excerpt = cursor.item().unwrap();
2747            let buffer = buffer.read(cx);
2748            let buffer_id = buffer.remote_id();
2749
2750            let mut new_excerpt;
2751            if buffer_edited {
2752                edits.extend(
2753                    buffer
2754                        .edits_since_in_range::<usize>(
2755                            old_excerpt.buffer.version(),
2756                            old_excerpt.range.context.clone(),
2757                        )
2758                        .map(|edit| {
2759                            let excerpt_old_start = cursor.start().1;
2760                            let excerpt_new_start =
2761                                ExcerptOffset::new(new_excerpts.summary().text.len);
2762                            let old_start = excerpt_old_start + ExcerptOffset::new(edit.old.start);
2763                            let old_end = excerpt_old_start + ExcerptOffset::new(edit.old.end);
2764                            let new_start = excerpt_new_start + ExcerptOffset::new(edit.new.start);
2765                            let new_end = excerpt_new_start + ExcerptOffset::new(edit.new.end);
2766                            Edit {
2767                                old: old_start..old_end,
2768                                new: new_start..new_end,
2769                            }
2770                        }),
2771                );
2772
2773                new_excerpt = Excerpt::new(
2774                    old_excerpt.id,
2775                    locator.clone(),
2776                    buffer_id,
2777                    buffer.snapshot(),
2778                    old_excerpt.range.clone(),
2779                    old_excerpt.has_trailing_newline,
2780                );
2781            } else {
2782                new_excerpt = old_excerpt.clone();
2783                new_excerpt.buffer = buffer.snapshot();
2784            }
2785
2786            new_excerpts.push(new_excerpt, &());
2787            cursor.next(&());
2788        }
2789        new_excerpts.append(cursor.suffix(&()), &());
2790
2791        drop(cursor);
2792        snapshot.excerpts = new_excerpts;
2793
2794        self.sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2795    }
2796
2797    fn sync_diff_transforms(
2798        &self,
2799        snapshot: &mut MultiBufferSnapshot,
2800        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
2801        change_kind: DiffChangeKind,
2802    ) {
2803        if excerpt_edits.is_empty() {
2804            return;
2805        }
2806
2807        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(&());
2808        let mut old_diff_transforms = snapshot
2809            .diff_transforms
2810            .cursor::<(ExcerptOffset, usize)>(&());
2811        let mut new_diff_transforms = SumTree::default();
2812        let mut old_expanded_hunks = HashSet::default();
2813        let mut output_edits = Vec::new();
2814        let mut output_delta = 0_isize;
2815        let mut at_transform_boundary = true;
2816        let mut end_of_current_insert = None;
2817
2818        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
2819        while let Some(edit) = excerpt_edits.next() {
2820            excerpts.seek_forward(&edit.new.start, Bias::Right, &());
2821            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
2822                excerpts.prev(&());
2823            }
2824
2825            // Keep any transforms that are before the edit.
2826            if at_transform_boundary {
2827                at_transform_boundary = false;
2828                let transforms_before_edit =
2829                    old_diff_transforms.slice(&edit.old.start, Bias::Left, &());
2830                self.append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
2831                if let Some(transform) = old_diff_transforms.item() {
2832                    if old_diff_transforms.end(&()).0 == edit.old.start
2833                        && old_diff_transforms.start().0 < edit.old.start
2834                    {
2835                        self.push_diff_transform(&mut new_diff_transforms, transform.clone());
2836                        old_diff_transforms.next(&());
2837                    }
2838                }
2839            }
2840
2841            // Compute the start of the edit in output coordinates.
2842            let edit_start_overshoot = (edit.old.start - old_diff_transforms.start().0).value;
2843            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
2844            let edit_new_start = (edit_old_start as isize + output_delta) as usize;
2845
2846            let changed_diff_hunks = self.recompute_diff_transforms_for_edit(
2847                &edit,
2848                &mut excerpts,
2849                &mut old_diff_transforms,
2850                &mut new_diff_transforms,
2851                &mut end_of_current_insert,
2852                &mut old_expanded_hunks,
2853                &snapshot,
2854                change_kind,
2855            );
2856
2857            // Compute the end of the edit in output coordinates.
2858            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
2859            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
2860            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot.value;
2861            let edit_new_end =
2862                new_diff_transforms.summary().output.len + edit_new_end_overshoot.value;
2863            let output_edit = Edit {
2864                old: edit_old_start..edit_old_end,
2865                new: edit_new_start..edit_new_end,
2866            };
2867
2868            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
2869            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
2870            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
2871                output_edits.push(output_edit);
2872            }
2873
2874            // If this is the last edit that intersects the current diff transform,
2875            // then recreate the content up to the end of this transform, to prepare
2876            // for reusing additional slices of the old transforms.
2877            if excerpt_edits.peek().map_or(true, |next_edit| {
2878                next_edit.old.start >= old_diff_transforms.end(&()).0
2879            }) {
2880                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
2881                    && match old_diff_transforms.item() {
2882                        Some(DiffTransform::BufferContent {
2883                            inserted_hunk_info: Some(hunk),
2884                            ..
2885                        }) => excerpts.item().is_some_and(|excerpt| {
2886                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
2887                        }),
2888                        _ => true,
2889                    };
2890
2891                let mut excerpt_offset = edit.new.end;
2892                if !keep_next_old_transform {
2893                    excerpt_offset += old_diff_transforms.end(&()).0 - edit.old.end;
2894                    old_diff_transforms.next(&());
2895                }
2896
2897                old_expanded_hunks.clear();
2898                self.push_buffer_content_transform(
2899                    &snapshot,
2900                    &mut new_diff_transforms,
2901                    excerpt_offset,
2902                    end_of_current_insert,
2903                );
2904                at_transform_boundary = true;
2905            }
2906        }
2907
2908        // Keep any transforms that are after the last edit.
2909        self.append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix(&()));
2910
2911        // Ensure there's always at least one buffer content transform.
2912        if new_diff_transforms.is_empty() {
2913            new_diff_transforms.push(
2914                DiffTransform::BufferContent {
2915                    summary: Default::default(),
2916                    inserted_hunk_info: None,
2917                },
2918                &(),
2919            );
2920        }
2921
2922        self.subscriptions.publish(output_edits);
2923        drop(old_diff_transforms);
2924        drop(excerpts);
2925        snapshot.diff_transforms = new_diff_transforms;
2926        snapshot.edit_count += 1;
2927
2928        #[cfg(any(test, feature = "test-support"))]
2929        snapshot.check_invariants();
2930    }
2931
2932    #[allow(clippy::too_many_arguments)]
2933    fn recompute_diff_transforms_for_edit(
2934        &self,
2935        edit: &Edit<TypedOffset<Excerpt>>,
2936        excerpts: &mut Cursor<Excerpt, TypedOffset<Excerpt>>,
2937        old_diff_transforms: &mut Cursor<DiffTransform, (TypedOffset<Excerpt>, usize)>,
2938        new_diff_transforms: &mut SumTree<DiffTransform>,
2939        end_of_current_insert: &mut Option<(TypedOffset<Excerpt>, DiffTransformHunkInfo)>,
2940        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
2941        snapshot: &MultiBufferSnapshot,
2942        change_kind: DiffChangeKind,
2943    ) -> bool {
2944        log::trace!(
2945            "recomputing diff transform for edit {:?} => {:?}",
2946            edit.old.start.value..edit.old.end.value,
2947            edit.new.start.value..edit.new.end.value
2948        );
2949
2950        // Record which hunks were previously expanded.
2951        while let Some(item) = old_diff_transforms.item() {
2952            if let Some(hunk_info) = item.hunk_info() {
2953                log::trace!(
2954                    "previously expanded hunk at {}",
2955                    old_diff_transforms.start().0
2956                );
2957                old_expanded_hunks.insert(hunk_info);
2958            }
2959            if old_diff_transforms.end(&()).0 > edit.old.end {
2960                break;
2961            }
2962            old_diff_transforms.next(&());
2963        }
2964
2965        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
2966        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
2967        if old_expanded_hunks.is_empty()
2968            && change_kind == DiffChangeKind::BufferEdited
2969            && !all_diff_hunks_expanded
2970        {
2971            return false;
2972        }
2973
2974        // Visit each excerpt that intersects the edit.
2975        let mut did_expand_hunks = false;
2976        while let Some(excerpt) = excerpts.item() {
2977            // Recompute the expanded hunks in the portion of the excerpt that
2978            // intersects the edit.
2979            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
2980                let buffer = &excerpt.buffer;
2981                let excerpt_start = *excerpts.start();
2982                let excerpt_end = excerpt_start + ExcerptOffset::new(excerpt.text_summary.len);
2983                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
2984                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
2985                let edit_buffer_start =
2986                    excerpt_buffer_start + edit.new.start.value.saturating_sub(excerpt_start.value);
2987                let edit_buffer_end =
2988                    excerpt_buffer_start + edit.new.end.value.saturating_sub(excerpt_start.value);
2989                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
2990                let edit_anchor_range =
2991                    buffer.anchor_before(edit_buffer_start)..buffer.anchor_after(edit_buffer_end);
2992
2993                for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
2994                    if hunk.is_created_file() && !all_diff_hunks_expanded {
2995                        continue;
2996                    }
2997
2998                    let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
2999                    if hunk_buffer_range.start < excerpt_buffer_start {
3000                        log::trace!("skipping hunk that starts before excerpt");
3001                        continue;
3002                    }
3003
3004                    let hunk_info = DiffTransformHunkInfo {
3005                        excerpt_id: excerpt.id,
3006                        hunk_start_anchor: hunk.buffer_range.start,
3007                        hunk_secondary_status: hunk.secondary_status,
3008                    };
3009
3010                    let hunk_excerpt_start = excerpt_start
3011                        + ExcerptOffset::new(
3012                            hunk_buffer_range.start.saturating_sub(excerpt_buffer_start),
3013                        );
3014                    let hunk_excerpt_end = excerpt_end.min(
3015                        excerpt_start
3016                            + ExcerptOffset::new(hunk_buffer_range.end - excerpt_buffer_start),
3017                    );
3018
3019                    self.push_buffer_content_transform(
3020                        snapshot,
3021                        new_diff_transforms,
3022                        hunk_excerpt_start,
3023                        *end_of_current_insert,
3024                    );
3025
3026                    // For every existing hunk, determine if it was previously expanded
3027                    // and if it should currently be expanded.
3028                    let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3029                    let should_expand_hunk = match &change_kind {
3030                        DiffChangeKind::DiffUpdated { base_changed: true } => {
3031                            was_previously_expanded || all_diff_hunks_expanded
3032                        }
3033                        DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3034                            let intersects = hunk_buffer_range.is_empty()
3035                                || hunk_buffer_range.end > edit_buffer_start;
3036                            if *expand {
3037                                intersects || was_previously_expanded || all_diff_hunks_expanded
3038                            } else {
3039                                !intersects && (was_previously_expanded || all_diff_hunks_expanded)
3040                            }
3041                        }
3042                        _ => was_previously_expanded || all_diff_hunks_expanded,
3043                    };
3044
3045                    if should_expand_hunk {
3046                        did_expand_hunks = true;
3047                        log::trace!(
3048                            "expanding hunk {:?}, excerpt:{:?}",
3049                            hunk_excerpt_start.value..hunk_excerpt_end.value,
3050                            excerpt.id
3051                        );
3052
3053                        if !hunk.diff_base_byte_range.is_empty()
3054                            && hunk_buffer_range.start >= edit_buffer_start
3055                            && hunk_buffer_range.start <= excerpt_buffer_end
3056                        {
3057                            let base_text = diff.base_text();
3058                            let mut text_cursor =
3059                                base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3060                            let mut base_text_summary =
3061                                text_cursor.summary::<TextSummary>(hunk.diff_base_byte_range.end);
3062
3063                            let mut has_trailing_newline = false;
3064                            if base_text_summary.last_line_chars > 0 {
3065                                base_text_summary += TextSummary::newline();
3066                                has_trailing_newline = true;
3067                            }
3068
3069                            new_diff_transforms.push(
3070                                DiffTransform::DeletedHunk {
3071                                    base_text_byte_range: hunk.diff_base_byte_range.clone(),
3072                                    summary: base_text_summary,
3073                                    buffer_id: excerpt.buffer_id,
3074                                    hunk_info,
3075                                    has_trailing_newline,
3076                                },
3077                                &(),
3078                            );
3079                        }
3080
3081                        if !hunk_buffer_range.is_empty() {
3082                            *end_of_current_insert =
3083                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3084                        }
3085                    }
3086                }
3087            }
3088
3089            if excerpts.end(&()) <= edit.new.end {
3090                excerpts.next(&());
3091            } else {
3092                break;
3093            }
3094        }
3095
3096        did_expand_hunks || !old_expanded_hunks.is_empty()
3097    }
3098
3099    fn append_diff_transforms(
3100        &self,
3101        new_transforms: &mut SumTree<DiffTransform>,
3102        subtree: SumTree<DiffTransform>,
3103    ) {
3104        if let Some(DiffTransform::BufferContent {
3105            inserted_hunk_info,
3106            summary,
3107        }) = subtree.first()
3108        {
3109            if self.extend_last_buffer_content_transform(
3110                new_transforms,
3111                *inserted_hunk_info,
3112                *summary,
3113            ) {
3114                let mut cursor = subtree.cursor::<()>(&());
3115                cursor.next(&());
3116                cursor.next(&());
3117                new_transforms.append(cursor.suffix(&()), &());
3118                return;
3119            }
3120        }
3121        new_transforms.append(subtree, &());
3122    }
3123
3124    fn push_diff_transform(
3125        &self,
3126        new_transforms: &mut SumTree<DiffTransform>,
3127        transform: DiffTransform,
3128    ) {
3129        if let DiffTransform::BufferContent {
3130            inserted_hunk_info: inserted_hunk_anchor,
3131            summary,
3132        } = transform
3133        {
3134            if self.extend_last_buffer_content_transform(
3135                new_transforms,
3136                inserted_hunk_anchor,
3137                summary,
3138            ) {
3139                return;
3140            }
3141        }
3142        new_transforms.push(transform, &());
3143    }
3144
3145    fn push_buffer_content_transform(
3146        &self,
3147        old_snapshot: &MultiBufferSnapshot,
3148        new_transforms: &mut SumTree<DiffTransform>,
3149        end_offset: ExcerptOffset,
3150        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3151    ) {
3152        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3153            (end_offset.min(insertion_end_offset), Some(hunk_info))
3154        });
3155        let unchanged_region = [(end_offset, None)];
3156
3157        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3158        {
3159            let start_offset = new_transforms.summary().excerpt_len();
3160            if end_offset <= start_offset {
3161                continue;
3162            }
3163            let summary_to_add = old_snapshot
3164                .text_summary_for_excerpt_offset_range::<TextSummary>(start_offset..end_offset);
3165
3166            if !self.extend_last_buffer_content_transform(
3167                new_transforms,
3168                inserted_hunk_info,
3169                summary_to_add,
3170            ) {
3171                new_transforms.push(
3172                    DiffTransform::BufferContent {
3173                        summary: summary_to_add,
3174                        inserted_hunk_info,
3175                    },
3176                    &(),
3177                )
3178            }
3179        }
3180    }
3181
3182    fn extend_last_buffer_content_transform(
3183        &self,
3184        new_transforms: &mut SumTree<DiffTransform>,
3185        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3186        summary_to_add: TextSummary,
3187    ) -> bool {
3188        let mut did_extend = false;
3189        new_transforms.update_last(
3190            |last_transform| {
3191                if let DiffTransform::BufferContent {
3192                    summary,
3193                    inserted_hunk_info: inserted_hunk_anchor,
3194                } = last_transform
3195                {
3196                    if *inserted_hunk_anchor == new_inserted_hunk_info {
3197                        *summary += summary_to_add;
3198                        did_extend = true;
3199                    }
3200                }
3201            },
3202            &(),
3203        );
3204        did_extend
3205    }
3206}
3207
3208#[cfg(any(test, feature = "test-support"))]
3209impl MultiBuffer {
3210    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3211        let buffer = cx.new(|cx| Buffer::local(text, cx));
3212        cx.new(|cx| Self::singleton(buffer, cx))
3213    }
3214
3215    pub fn build_multi<const COUNT: usize>(
3216        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3217        cx: &mut gpui::App,
3218    ) -> Entity<Self> {
3219        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3220        for (text, ranges) in excerpts {
3221            let buffer = cx.new(|cx| Buffer::local(text, cx));
3222            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
3223                context: range,
3224                primary: None,
3225            });
3226            multi.update(cx, |multi, cx| {
3227                multi.push_excerpts(buffer, excerpt_ranges, cx)
3228            });
3229        }
3230
3231        multi
3232    }
3233
3234    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3235        cx.new(|cx| Self::singleton(buffer, cx))
3236    }
3237
3238    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3239        cx.new(|cx| {
3240            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3241            let mutation_count = rng.gen_range(1..=5);
3242            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3243            multibuffer
3244        })
3245    }
3246
3247    pub fn randomly_edit(
3248        &mut self,
3249        rng: &mut impl rand::Rng,
3250        edit_count: usize,
3251        cx: &mut Context<Self>,
3252    ) {
3253        use util::RandomCharIter;
3254
3255        let snapshot = self.read(cx);
3256        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
3257        let mut last_end = None;
3258        for _ in 0..edit_count {
3259            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
3260                break;
3261            }
3262
3263            let new_start = last_end.map_or(0, |last_end| last_end + 1);
3264            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
3265            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
3266            last_end = Some(end);
3267
3268            let mut range = start..end;
3269            if rng.gen_bool(0.2) {
3270                mem::swap(&mut range.start, &mut range.end);
3271            }
3272
3273            let new_text_len = rng.gen_range(0..10);
3274            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3275
3276            edits.push((range, new_text.into()));
3277        }
3278        log::info!("mutating multi-buffer with {:?}", edits);
3279        drop(snapshot);
3280
3281        self.edit(edits, None, cx);
3282    }
3283
3284    pub fn randomly_edit_excerpts(
3285        &mut self,
3286        rng: &mut impl rand::Rng,
3287        mutation_count: usize,
3288        cx: &mut Context<Self>,
3289    ) {
3290        use rand::prelude::*;
3291        use std::env;
3292        use util::RandomCharIter;
3293
3294        let max_excerpts = env::var("MAX_EXCERPTS")
3295            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3296            .unwrap_or(5);
3297
3298        let mut buffers = Vec::new();
3299        for _ in 0..mutation_count {
3300            if rng.gen_bool(0.05) {
3301                log::info!("Clearing multi-buffer");
3302                self.clear(cx);
3303                continue;
3304            } else if rng.gen_bool(0.1) && !self.excerpt_ids().is_empty() {
3305                let ids = self.excerpt_ids();
3306                let mut excerpts = HashSet::default();
3307                for _ in 0..rng.gen_range(0..ids.len()) {
3308                    excerpts.extend(ids.choose(rng).copied());
3309                }
3310
3311                let line_count = rng.gen_range(0..5);
3312
3313                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3314
3315                self.expand_excerpts(
3316                    excerpts.iter().cloned(),
3317                    line_count,
3318                    ExpandExcerptDirection::UpAndDown,
3319                    cx,
3320                );
3321                continue;
3322            }
3323
3324            let excerpt_ids = self.excerpt_ids();
3325            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
3326                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
3327                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3328                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3329                    let buffer = buffers.last().unwrap().read(cx);
3330                    log::info!(
3331                        "Creating new buffer {} with text: {:?}",
3332                        buffer.remote_id(),
3333                        buffer.text()
3334                    );
3335                    buffers.last().unwrap().clone()
3336                } else {
3337                    self.buffers
3338                        .borrow()
3339                        .values()
3340                        .choose(rng)
3341                        .unwrap()
3342                        .buffer
3343                        .clone()
3344                };
3345
3346                let buffer = buffer_handle.read(cx);
3347                let buffer_text = buffer.text();
3348                let ranges = (0..rng.gen_range(0..5))
3349                    .map(|_| {
3350                        let end_ix =
3351                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3352                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3353                        ExcerptRange {
3354                            context: start_ix..end_ix,
3355                            primary: None,
3356                        }
3357                    })
3358                    .collect::<Vec<_>>();
3359                log::info!(
3360                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3361                    buffer_handle.read(cx).remote_id(),
3362                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3363                    ranges
3364                        .iter()
3365                        .map(|r| &buffer_text[r.context.clone()])
3366                        .collect::<Vec<_>>()
3367                );
3368
3369                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
3370                log::info!("Inserted with ids: {:?}", excerpt_id);
3371            } else {
3372                let remove_count = rng.gen_range(1..=excerpt_ids.len());
3373                let mut excerpts_to_remove = excerpt_ids
3374                    .choose_multiple(rng, remove_count)
3375                    .cloned()
3376                    .collect::<Vec<_>>();
3377                let snapshot = self.snapshot.borrow();
3378                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3379                drop(snapshot);
3380                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3381                self.remove_excerpts(excerpts_to_remove, cx);
3382            }
3383        }
3384    }
3385
3386    pub fn randomly_mutate(
3387        &mut self,
3388        rng: &mut impl rand::Rng,
3389        mutation_count: usize,
3390        cx: &mut Context<Self>,
3391    ) {
3392        use rand::prelude::*;
3393
3394        if rng.gen_bool(0.7) || self.singleton {
3395            let buffer = self
3396                .buffers
3397                .borrow()
3398                .values()
3399                .choose(rng)
3400                .map(|state| state.buffer.clone());
3401
3402            if let Some(buffer) = buffer {
3403                buffer.update(cx, |buffer, cx| {
3404                    if rng.gen() {
3405                        buffer.randomly_edit(rng, mutation_count, cx);
3406                    } else {
3407                        buffer.randomly_undo_redo(rng, cx);
3408                    }
3409                });
3410            } else {
3411                self.randomly_edit(rng, mutation_count, cx);
3412            }
3413        } else {
3414            self.randomly_edit_excerpts(rng, mutation_count, cx);
3415        }
3416
3417        self.check_invariants(cx);
3418    }
3419
3420    fn check_invariants(&self, cx: &App) {
3421        self.read(cx).check_invariants();
3422    }
3423}
3424
3425impl EventEmitter<Event> for MultiBuffer {}
3426
3427impl MultiBufferSnapshot {
3428    pub fn text(&self) -> String {
3429        self.chunks(0..self.len(), false)
3430            .map(|chunk| chunk.text)
3431            .collect()
3432    }
3433
3434    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3435        self.reversed_chunks_in_range(0..position.to_offset(self))
3436            .flat_map(|c| c.chars().rev())
3437    }
3438
3439    fn reversed_chunks_in_range(&self, range: Range<usize>) -> ReversedMultiBufferChunks {
3440        let mut cursor = self.cursor::<usize>();
3441        cursor.seek(&range.end);
3442        let current_chunks = cursor.region().as_ref().map(|region| {
3443            let start_overshoot = range.start.saturating_sub(region.range.start);
3444            let end_overshoot = range.end - region.range.start;
3445            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3446            let start = region.buffer_range.start + start_overshoot;
3447            region.buffer.reversed_chunks_in_range(start..end)
3448        });
3449        ReversedMultiBufferChunks {
3450            cursor,
3451            current_chunks,
3452            start: range.start,
3453            offset: range.end,
3454        }
3455    }
3456
3457    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3458        let offset = position.to_offset(self);
3459        self.text_for_range(offset..self.len())
3460            .flat_map(|chunk| chunk.chars())
3461    }
3462
3463    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3464        self.chunks(range, false).map(|chunk| chunk.text)
3465    }
3466
3467    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3468        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3469            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3470    }
3471
3472    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3473    where
3474        T: ToOffset,
3475    {
3476        let position = position.to_offset(self);
3477        position == self.clip_offset(position, Bias::Left)
3478            && self
3479                .bytes_in_range(position..self.len())
3480                .flatten()
3481                .copied()
3482                .take(needle.len())
3483                .eq(needle.bytes())
3484    }
3485
3486    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3487        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
3488    }
3489
3490    pub fn diff_hunks_in_range<T: ToPoint>(
3491        &self,
3492        range: Range<T>,
3493    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3494        let query_range = range.start.to_point(self)..range.end.to_point(self);
3495        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
3496            let Some(diff) = self.diffs.get(&buffer.remote_id()) else {
3497                log::debug!("no diff found for {:?}", buffer.remote_id());
3498                return None;
3499            };
3500            let buffer_start = buffer.anchor_before(buffer_range.start);
3501            let buffer_end = buffer.anchor_after(buffer_range.end);
3502            Some(
3503                diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
3504                    .filter_map(|hunk| {
3505                        if hunk.is_created_file() && !self.all_diff_hunks_expanded {
3506                            return None;
3507                        }
3508                        Some((hunk.range.clone(), hunk))
3509                    }),
3510            )
3511        })
3512        .filter_map(move |(range, hunk, excerpt)| {
3513            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
3514            {
3515                return None;
3516            }
3517            let end_row = if range.end.column == 0 {
3518                range.end.row
3519            } else {
3520                range.end.row + 1
3521            };
3522            Some(MultiBufferDiffHunk {
3523                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
3524                buffer_id: excerpt.buffer_id,
3525                excerpt_id: excerpt.id,
3526                buffer_range: hunk.buffer_range.clone(),
3527                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3528                secondary_status: hunk.secondary_status,
3529            })
3530        })
3531    }
3532
3533    pub fn excerpt_ids_for_range<T: ToOffset>(
3534        &self,
3535        range: Range<T>,
3536    ) -> impl Iterator<Item = ExcerptId> + '_ {
3537        let range = range.start.to_offset(self)..range.end.to_offset(self);
3538        let mut cursor = self.cursor::<usize>();
3539        cursor.seek(&range.start);
3540        std::iter::from_fn(move || {
3541            let region = cursor.region()?;
3542            if region.range.start >= range.end {
3543                return None;
3544            }
3545            cursor.next_excerpt();
3546            Some(region.excerpt.id)
3547        })
3548    }
3549
3550    pub fn buffer_ids_for_range<T: ToOffset>(
3551        &self,
3552        range: Range<T>,
3553    ) -> impl Iterator<Item = BufferId> + '_ {
3554        let range = range.start.to_offset(self)..range.end.to_offset(self);
3555        let mut cursor = self.cursor::<usize>();
3556        cursor.seek(&range.start);
3557        std::iter::from_fn(move || {
3558            let region = cursor.region()?;
3559            if region.range.start > range.end
3560                || region.range.start == range.end && region.range.start > range.start
3561            {
3562                return None;
3563            }
3564            cursor.next_excerpt();
3565            Some(region.excerpt.buffer_id)
3566        })
3567    }
3568
3569    pub fn ranges_to_buffer_ranges<T: ToOffset>(
3570        &self,
3571        ranges: impl Iterator<Item = Range<T>>,
3572    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId)> {
3573        ranges.flat_map(|range| self.range_to_buffer_ranges(range).into_iter())
3574    }
3575
3576    pub fn range_to_buffer_ranges<T: ToOffset>(
3577        &self,
3578        range: Range<T>,
3579    ) -> Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> {
3580        let start = range.start.to_offset(&self);
3581        let end = range.end.to_offset(&self);
3582
3583        let mut cursor = self.cursor::<usize>();
3584        cursor.seek(&start);
3585
3586        let mut result: Vec<(&BufferSnapshot, Range<usize>, ExcerptId)> = Vec::new();
3587        while let Some(region) = cursor.region() {
3588            if region.range.start > end {
3589                break;
3590            }
3591            if region.is_main_buffer {
3592                let start_overshoot = start.saturating_sub(region.range.start);
3593                let end_overshoot = end.saturating_sub(region.range.start);
3594                let start = region
3595                    .buffer_range
3596                    .end
3597                    .min(region.buffer_range.start + start_overshoot);
3598                let end = region
3599                    .buffer_range
3600                    .end
3601                    .min(region.buffer_range.start + end_overshoot);
3602                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id)| {
3603                    *excerpt_id == region.excerpt.id && prev_range.end == start
3604                }) {
3605                    prev.1.end = end;
3606                } else {
3607                    result.push((region.buffer, start..end, region.excerpt.id));
3608                }
3609            }
3610            cursor.next();
3611        }
3612        result
3613    }
3614
3615    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
3616        &self,
3617        range: Range<T>,
3618    ) -> impl Iterator<Item = (&BufferSnapshot, Range<usize>, ExcerptId, Option<Anchor>)> + '_ {
3619        let start = range.start.to_offset(&self);
3620        let end = range.end.to_offset(&self);
3621
3622        let mut cursor = self.cursor::<usize>();
3623        cursor.seek(&start);
3624
3625        std::iter::from_fn(move || {
3626            let region = cursor.region()?;
3627            if region.range.start > end {
3628                return None;
3629            }
3630            let start_overshoot = start.saturating_sub(region.range.start);
3631            let end_overshoot = end.saturating_sub(region.range.start);
3632            let start = region
3633                .buffer_range
3634                .end
3635                .min(region.buffer_range.start + start_overshoot);
3636            let end = region
3637                .buffer_range
3638                .end
3639                .min(region.buffer_range.start + end_overshoot);
3640
3641            let region_excerpt_id = region.excerpt.id;
3642            let deleted_hunk_anchor = if region.is_main_buffer {
3643                None
3644            } else {
3645                Some(self.anchor_before(region.range.start))
3646            };
3647            let result = (
3648                region.buffer,
3649                start..end,
3650                region_excerpt_id,
3651                deleted_hunk_anchor,
3652            );
3653            cursor.next();
3654            Some(result)
3655        })
3656    }
3657
3658    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
3659    /// coordinates.
3660    ///
3661    /// The given callback will be called for every excerpt intersecting the given range. It will
3662    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
3663    /// The callback should return an iterator of metadata items from that buffer, each paired
3664    /// with a buffer range.
3665    ///
3666    /// The returned iterator yields each of these metadata items, paired with its range in
3667    /// multi-buffer coordinates.
3668    fn lift_buffer_metadata<'a, D, M, I>(
3669        &'a self,
3670        query_range: Range<D>,
3671        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<D>) -> Option<I>,
3672    ) -> impl Iterator<Item = (Range<D>, M, &'a Excerpt)> + 'a
3673    where
3674        I: Iterator<Item = (Range<D>, M)> + 'a,
3675        D: TextDimension + Ord + Sub<D, Output = D>,
3676    {
3677        let max_position = D::from_text_summary(&self.text_summary());
3678        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
3679        let mut cursor = self.cursor::<D>();
3680
3681        // Find the excerpt and buffer offset where the given range ends.
3682        cursor.seek(&query_range.end);
3683        let mut range_end = None;
3684        while let Some(region) = cursor.region() {
3685            if region.is_main_buffer {
3686                let mut buffer_end = region.buffer_range.start;
3687                let overshoot = if query_range.end > region.range.start {
3688                    query_range.end - region.range.start
3689                } else {
3690                    D::default()
3691                };
3692                buffer_end.add_assign(&overshoot);
3693                range_end = Some((region.excerpt.id, buffer_end));
3694                break;
3695            }
3696            cursor.next();
3697        }
3698
3699        cursor.seek(&query_range.start);
3700
3701        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer) {
3702            if region.range.start > D::zero(&()) {
3703                cursor.prev()
3704            }
3705        }
3706
3707        iter::from_fn(move || loop {
3708            let excerpt = cursor.excerpt()?;
3709
3710            // If we have already retrieved metadata for this excerpt, continue to use it.
3711            let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
3712                .as_mut()
3713                .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
3714            {
3715                Some(metadata)
3716            }
3717            // Otherwise, compute the intersection of the input range with the excerpt's range,
3718            // and retrieve the metadata for the resulting range.
3719            else {
3720                let region = cursor.region()?;
3721                let mut buffer_start;
3722                if region.is_main_buffer {
3723                    buffer_start = region.buffer_range.start;
3724                    if query_range.start > region.range.start {
3725                        let overshoot = query_range.start - region.range.start;
3726                        buffer_start.add_assign(&overshoot);
3727                    }
3728                    buffer_start = buffer_start.min(region.buffer_range.end);
3729                } else {
3730                    buffer_start = cursor.main_buffer_position()?;
3731                };
3732                let mut buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
3733                if let Some((end_excerpt_id, end_buffer_offset)) = range_end {
3734                    if excerpt.id == end_excerpt_id {
3735                        buffer_end = buffer_end.min(end_buffer_offset);
3736                    }
3737                }
3738
3739                if let Some(iterator) =
3740                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end)
3741                {
3742                    Some(&mut current_excerpt_metadata.insert((excerpt.id, iterator)).1)
3743                } else {
3744                    None
3745                }
3746            };
3747
3748            // Visit each metadata item.
3749            if let Some((metadata_buffer_range, metadata)) = metadata_iter.and_then(Iterator::next)
3750            {
3751                // Find the multibuffer regions that contain the start and end of
3752                // the metadata item's range.
3753                if metadata_buffer_range.start > D::default() {
3754                    while let Some(region) = cursor.region() {
3755                        if region.is_main_buffer
3756                            && (region.buffer_range.end >= metadata_buffer_range.start
3757                                || cursor.is_at_end_of_excerpt())
3758                        {
3759                            break;
3760                        }
3761                        cursor.next();
3762                    }
3763                }
3764                let start_region = cursor.region()?;
3765                while let Some(region) = cursor.region() {
3766                    if region.is_main_buffer
3767                        && (region.buffer_range.end > metadata_buffer_range.end
3768                            || cursor.is_at_end_of_excerpt())
3769                    {
3770                        break;
3771                    }
3772                    cursor.next();
3773                }
3774                let end_region = cursor.region();
3775
3776                // Convert the metadata item's range into multibuffer coordinates.
3777                let mut start_position = start_region.range.start;
3778                let region_buffer_start = start_region.buffer_range.start;
3779                if start_region.is_main_buffer && metadata_buffer_range.start > region_buffer_start
3780                {
3781                    start_position.add_assign(&(metadata_buffer_range.start - region_buffer_start));
3782                    start_position = start_position.min(start_region.range.end);
3783                }
3784
3785                let mut end_position = max_position;
3786                if let Some(end_region) = &end_region {
3787                    end_position = end_region.range.start;
3788                    debug_assert!(end_region.is_main_buffer);
3789                    let region_buffer_start = end_region.buffer_range.start;
3790                    if metadata_buffer_range.end > region_buffer_start {
3791                        end_position.add_assign(&(metadata_buffer_range.end - region_buffer_start));
3792                    }
3793                    end_position = end_position.min(end_region.range.end);
3794                }
3795
3796                if start_position <= query_range.end && end_position >= query_range.start {
3797                    return Some((start_position..end_position, metadata, excerpt));
3798                }
3799            }
3800            // When there are no more metadata items for this excerpt, move to the next excerpt.
3801            else {
3802                current_excerpt_metadata.take();
3803                cursor.next_excerpt();
3804            }
3805        })
3806    }
3807
3808    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
3809        let offset = position.to_offset(self);
3810
3811        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
3812        cursor.seek(&DimensionPair {
3813            key: offset,
3814            value: None,
3815        });
3816        cursor.seek_to_start_of_current_excerpt();
3817        let excerpt = cursor.excerpt()?;
3818
3819        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
3820        let current_position = self
3821            .anchor_before(offset)
3822            .text_anchor
3823            .to_offset(&excerpt.buffer);
3824        let excerpt_end = excerpt
3825            .buffer
3826            .anchor_before(excerpt_end.min(current_position));
3827
3828        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
3829            for hunk in diff.hunks_intersecting_range_rev(
3830                excerpt.range.context.start..excerpt_end,
3831                &excerpt.buffer,
3832            ) {
3833                let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
3834                if hunk_end >= current_position {
3835                    continue;
3836                }
3837                let start =
3838                    Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
3839                        .to_point(&self);
3840                return Some(MultiBufferRow(start.row));
3841            }
3842        }
3843
3844        loop {
3845            cursor.prev_excerpt();
3846            let excerpt = cursor.excerpt()?;
3847
3848            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
3849                continue;
3850            };
3851            let mut hunks =
3852                diff.hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer);
3853            let Some(hunk) = hunks.next() else {
3854                continue;
3855            };
3856            let start = Anchor::in_buffer(excerpt.id, excerpt.buffer_id, hunk.buffer_range.start)
3857                .to_point(&self);
3858            return Some(MultiBufferRow(start.row));
3859        }
3860    }
3861
3862    pub fn has_diff_hunks(&self) -> bool {
3863        self.diffs.values().any(|diff| !diff.is_empty())
3864    }
3865
3866    pub fn surrounding_word<T: ToOffset>(
3867        &self,
3868        start: T,
3869        for_completion: bool,
3870    ) -> (Range<usize>, Option<CharKind>) {
3871        let mut start = start.to_offset(self);
3872        let mut end = start;
3873        let mut next_chars = self.chars_at(start).peekable();
3874        let mut prev_chars = self.reversed_chars_at(start).peekable();
3875
3876        let classifier = self
3877            .char_classifier_at(start)
3878            .for_completion(for_completion);
3879
3880        let word_kind = cmp::max(
3881            prev_chars.peek().copied().map(|c| classifier.kind(c)),
3882            next_chars.peek().copied().map(|c| classifier.kind(c)),
3883        );
3884
3885        for ch in prev_chars {
3886            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
3887                start -= ch.len_utf8();
3888            } else {
3889                break;
3890            }
3891        }
3892
3893        for ch in next_chars {
3894            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
3895                end += ch.len_utf8();
3896            } else {
3897                break;
3898            }
3899        }
3900
3901        (start..end, word_kind)
3902    }
3903
3904    pub fn is_singleton(&self) -> bool {
3905        self.singleton
3906    }
3907
3908    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
3909        if self.singleton {
3910            self.excerpts
3911                .iter()
3912                .next()
3913                .map(|e| (&e.id, e.buffer_id, &e.buffer))
3914        } else {
3915            None
3916        }
3917    }
3918
3919    pub fn len(&self) -> usize {
3920        self.diff_transforms.summary().output.len
3921    }
3922
3923    pub fn is_empty(&self) -> bool {
3924        self.excerpts.summary().text.len == 0
3925    }
3926
3927    pub fn widest_line_number(&self) -> u32 {
3928        self.excerpts.summary().widest_line_number + 1
3929    }
3930
3931    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
3932        let range = range.start.to_offset(self)..range.end.to_offset(self);
3933        let mut excerpts = self.cursor::<usize>();
3934        excerpts.seek(&range.start);
3935
3936        let mut chunk;
3937        let mut has_trailing_newline;
3938        let excerpt_bytes;
3939        if let Some(region) = excerpts.region() {
3940            let mut bytes = region.buffer.bytes_in_range(
3941                region.buffer_range.start + range.start - region.range.start
3942                    ..(region.buffer_range.start + range.end - region.range.start)
3943                        .min(region.buffer_range.end),
3944            );
3945            chunk = bytes.next().unwrap_or(&[][..]);
3946            excerpt_bytes = Some(bytes);
3947            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
3948            if chunk.is_empty() && has_trailing_newline {
3949                chunk = b"\n";
3950                has_trailing_newline = false;
3951            }
3952        } else {
3953            chunk = &[][..];
3954            excerpt_bytes = None;
3955            has_trailing_newline = false;
3956        };
3957
3958        MultiBufferBytes {
3959            range,
3960            cursor: excerpts,
3961            excerpt_bytes,
3962            has_trailing_newline,
3963            chunk,
3964        }
3965    }
3966
3967    pub fn reversed_bytes_in_range<T: ToOffset>(
3968        &self,
3969        range: Range<T>,
3970    ) -> ReversedMultiBufferBytes {
3971        let range = range.start.to_offset(self)..range.end.to_offset(self);
3972        let mut chunks = self.reversed_chunks_in_range(range.clone());
3973        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
3974        ReversedMultiBufferBytes {
3975            range,
3976            chunks,
3977            chunk,
3978        }
3979    }
3980
3981    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows {
3982        let mut cursor = self.cursor::<Point>();
3983        cursor.seek(&Point::new(start_row.0, 0));
3984        let mut result = MultiBufferRows {
3985            point: Point::new(0, 0),
3986            is_empty: self.excerpts.is_empty(),
3987            cursor,
3988        };
3989        result.seek(start_row);
3990        result
3991    }
3992
3993    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
3994        let mut chunks = MultiBufferChunks {
3995            excerpt_offset_range: ExcerptOffset::new(0)..ExcerptOffset::new(0),
3996            range: 0..0,
3997            excerpts: self.excerpts.cursor(&()),
3998            diff_transforms: self.diff_transforms.cursor(&()),
3999            diffs: &self.diffs,
4000            diff_base_chunks: None,
4001            excerpt_chunks: None,
4002            buffer_chunk: None,
4003            language_aware,
4004        };
4005        let range = range.start.to_offset(self)..range.end.to_offset(self);
4006        chunks.seek(range);
4007        chunks
4008    }
4009
4010    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
4011        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4012    }
4013
4014    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4015        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4016    }
4017
4018    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
4019        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4020    }
4021
4022    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4023        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4024            buffer.clip_point_utf16(Unclipped(point), bias)
4025        })
4026    }
4027
4028    pub fn offset_to_point(&self, offset: usize) -> Point {
4029        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4030    }
4031
4032    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
4033        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4034    }
4035
4036    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4037        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4038    }
4039
4040    pub fn point_to_offset(&self, point: Point) -> usize {
4041        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4042    }
4043
4044    pub fn offset_utf16_to_offset(&self, offset: OffsetUtf16) -> usize {
4045        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4046    }
4047
4048    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
4049        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4050    }
4051
4052    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
4053        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4054    }
4055
4056    fn clip_dimension<D>(
4057        &self,
4058        position: D,
4059        bias: Bias,
4060        clip_buffer_position: fn(&text::BufferSnapshot, D, Bias) -> D,
4061    ) -> D
4062    where
4063        D: TextDimension + Ord + Sub<D, Output = D>,
4064    {
4065        let mut cursor = self.cursor();
4066        cursor.seek(&position);
4067        if let Some(region) = cursor.region() {
4068            if position >= region.range.end {
4069                return region.range.end;
4070            }
4071            let overshoot = position - region.range.start;
4072            let mut buffer_position = region.buffer_range.start;
4073            buffer_position.add_assign(&overshoot);
4074            let clipped_buffer_position =
4075                clip_buffer_position(&region.buffer, buffer_position, bias);
4076            let mut position = region.range.start;
4077            position.add_assign(&(clipped_buffer_position - region.buffer_range.start));
4078            position
4079        } else {
4080            D::from_text_summary(&self.text_summary())
4081        }
4082    }
4083
4084    fn convert_dimension<D1, D2>(
4085        &self,
4086        key: D1,
4087        convert_buffer_dimension: fn(&text::BufferSnapshot, D1) -> D2,
4088    ) -> D2
4089    where
4090        D1: TextDimension + Ord + Sub<D1, Output = D1>,
4091        D2: TextDimension + Ord + Sub<D2, Output = D2>,
4092    {
4093        let mut cursor = self.cursor::<DimensionPair<D1, D2>>();
4094        cursor.seek(&DimensionPair { key, value: None });
4095        if let Some(region) = cursor.region() {
4096            if key >= region.range.end.key {
4097                return region.range.end.value.unwrap();
4098            }
4099            let start_key = region.range.start.key;
4100            let start_value = region.range.start.value.unwrap();
4101            let buffer_start_key = region.buffer_range.start.key;
4102            let buffer_start_value = region.buffer_range.start.value.unwrap();
4103            let mut buffer_key = buffer_start_key;
4104            buffer_key.add_assign(&(key - start_key));
4105            let buffer_value = convert_buffer_dimension(&region.buffer, buffer_key);
4106            let mut result = start_value;
4107            result.add_assign(&(buffer_value - buffer_start_value));
4108            result
4109        } else {
4110            D2::from_text_summary(&self.text_summary())
4111        }
4112    }
4113
4114    pub fn point_to_buffer_offset<T: ToOffset>(
4115        &self,
4116        point: T,
4117    ) -> Option<(&BufferSnapshot, usize)> {
4118        let offset = point.to_offset(self);
4119        let mut cursor = self.cursor::<usize>();
4120        cursor.seek(&offset);
4121        let region = cursor.region()?;
4122        let overshoot = offset - region.range.start;
4123        let buffer_offset = region.buffer_range.start + overshoot;
4124        Some((region.buffer, buffer_offset))
4125    }
4126
4127    pub fn point_to_buffer_point(&self, point: Point) -> Option<(&BufferSnapshot, Point, bool)> {
4128        let mut cursor = self.cursor::<Point>();
4129        cursor.seek(&point);
4130        let region = cursor.region()?;
4131        let overshoot = point - region.range.start;
4132        let buffer_offset = region.buffer_range.start + overshoot;
4133        Some((region.buffer, buffer_offset, region.is_main_buffer))
4134    }
4135
4136    pub fn suggested_indents(
4137        &self,
4138        rows: impl IntoIterator<Item = u32>,
4139        cx: &App,
4140    ) -> BTreeMap<MultiBufferRow, IndentSize> {
4141        let mut result = BTreeMap::new();
4142
4143        let mut rows_for_excerpt = Vec::new();
4144        let mut cursor = self.cursor::<Point>();
4145        let mut rows = rows.into_iter().peekable();
4146        let mut prev_row = u32::MAX;
4147        let mut prev_language_indent_size = IndentSize::default();
4148
4149        while let Some(row) = rows.next() {
4150            cursor.seek(&Point::new(row, 0));
4151            let Some(region) = cursor.region() else {
4152                continue;
4153            };
4154
4155            // Retrieve the language and indent size once for each disjoint region being indented.
4156            let single_indent_size = if row.saturating_sub(1) == prev_row {
4157                prev_language_indent_size
4158            } else {
4159                region
4160                    .buffer
4161                    .language_indent_size_at(Point::new(row, 0), cx)
4162            };
4163            prev_language_indent_size = single_indent_size;
4164            prev_row = row;
4165
4166            let start_buffer_row = region.buffer_range.start.row;
4167            let start_multibuffer_row = region.range.start.row;
4168            let end_multibuffer_row = region.range.end.row;
4169
4170            rows_for_excerpt.push(row);
4171            while let Some(next_row) = rows.peek().copied() {
4172                if end_multibuffer_row > next_row {
4173                    rows_for_excerpt.push(next_row);
4174                    rows.next();
4175                } else {
4176                    break;
4177                }
4178            }
4179
4180            let buffer_rows = rows_for_excerpt
4181                .drain(..)
4182                .map(|row| start_buffer_row + row - start_multibuffer_row);
4183            let buffer_indents = region
4184                .buffer
4185                .suggested_indents(buffer_rows, single_indent_size);
4186            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
4187                (
4188                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
4189                    indent,
4190                )
4191            });
4192            result.extend(multibuffer_indents);
4193        }
4194
4195        result
4196    }
4197
4198    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
4199        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4200            let mut size = buffer.indent_size_for_line(range.start.row);
4201            size.len = size
4202                .len
4203                .min(range.end.column)
4204                .saturating_sub(range.start.column);
4205            size
4206        } else {
4207            IndentSize::spaces(0)
4208        }
4209    }
4210
4211    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
4212        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
4213            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
4214        } else {
4215            LineIndent::spaces(0)
4216        }
4217    }
4218
4219    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
4220        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
4221
4222        if self.settings_at(0, cx).extend_comment_on_newline {
4223            if let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0)) {
4224                let delimiters = language_scope.line_comment_prefixes();
4225                for delimiter in delimiters {
4226                    if *self
4227                        .chars_at(Point::new(row.0, indent.len() as u32))
4228                        .take(delimiter.chars().count())
4229                        .collect::<String>()
4230                        .as_str()
4231                        == **delimiter
4232                    {
4233                        indent.push_str(&delimiter);
4234                        break;
4235                    }
4236                }
4237            }
4238        }
4239
4240        indent
4241    }
4242
4243    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
4244    where
4245        T: ToOffset,
4246    {
4247        for char in self.reversed_chars_at(position) {
4248            if !char.is_whitespace() {
4249                return false;
4250            }
4251            if char == '\n' {
4252                return true;
4253            }
4254        }
4255        return true;
4256    }
4257
4258    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
4259        while row.0 > 0 {
4260            row.0 -= 1;
4261            if !self.is_line_blank(row) {
4262                return Some(row);
4263            }
4264        }
4265        None
4266    }
4267
4268    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
4269        if let Some((_, range)) = self.buffer_line_for_row(row) {
4270            range.end.column - range.start.column
4271        } else {
4272            0
4273        }
4274    }
4275
4276    pub fn buffer_line_for_row(
4277        &self,
4278        row: MultiBufferRow,
4279    ) -> Option<(&BufferSnapshot, Range<Point>)> {
4280        let mut cursor = self.cursor::<Point>();
4281        let point = Point::new(row.0, 0);
4282        cursor.seek(&point);
4283        let region = cursor.region()?;
4284        let overshoot = point.min(region.range.end) - region.range.start;
4285        let buffer_point = region.buffer_range.start + overshoot;
4286        if buffer_point.row > region.buffer_range.end.row {
4287            return None;
4288        }
4289        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
4290        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
4291            .min(region.buffer_range.end);
4292        Some((region.buffer, line_start..line_end))
4293    }
4294
4295    pub fn max_point(&self) -> Point {
4296        self.text_summary().lines
4297    }
4298
4299    pub fn max_row(&self) -> MultiBufferRow {
4300        MultiBufferRow(self.text_summary().lines.row)
4301    }
4302
4303    pub fn text_summary(&self) -> TextSummary {
4304        self.diff_transforms.summary().output
4305    }
4306
4307    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
4308    where
4309        D: TextDimension,
4310        O: ToOffset,
4311    {
4312        let range = range.start.to_offset(self)..range.end.to_offset(self);
4313        let mut cursor = self.diff_transforms.cursor::<(usize, ExcerptOffset)>(&());
4314        cursor.seek(&range.start, Bias::Right, &());
4315
4316        let Some(first_transform) = cursor.item() else {
4317            return D::from_text_summary(&TextSummary::default());
4318        };
4319
4320        let diff_transform_start = cursor.start().0;
4321        let diff_transform_end = cursor.end(&()).0;
4322        let diff_start = range.start;
4323        let start_overshoot = diff_start - diff_transform_start;
4324        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
4325
4326        let mut result = match first_transform {
4327            DiffTransform::BufferContent { .. } => {
4328                let excerpt_start = cursor.start().1 + ExcerptOffset::new(start_overshoot);
4329                let excerpt_end = cursor.start().1 + ExcerptOffset::new(end_overshoot);
4330                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
4331            }
4332            DiffTransform::DeletedHunk {
4333                buffer_id,
4334                base_text_byte_range,
4335                has_trailing_newline,
4336                ..
4337            } => {
4338                let buffer_start = base_text_byte_range.start + start_overshoot;
4339                let mut buffer_end = base_text_byte_range.start + end_overshoot;
4340                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4341                    panic!("{:?} is in non-existent deleted hunk", range.start)
4342                };
4343
4344                let include_trailing_newline =
4345                    *has_trailing_newline && range.end >= diff_transform_end;
4346                if include_trailing_newline {
4347                    buffer_end -= 1;
4348                }
4349
4350                let mut summary =
4351                    base_text.text_summary_for_range::<D, _>(buffer_start..buffer_end);
4352
4353                if include_trailing_newline {
4354                    summary.add_assign(&D::from_text_summary(&TextSummary::newline()))
4355                }
4356
4357                summary
4358            }
4359        };
4360        if range.end < diff_transform_end {
4361            return result;
4362        }
4363
4364        cursor.next(&());
4365        result.add_assign(&D::from_text_summary(&cursor.summary(
4366            &range.end,
4367            Bias::Right,
4368            &(),
4369        )));
4370
4371        let Some(last_transform) = cursor.item() else {
4372            return result;
4373        };
4374
4375        let overshoot = range.end - cursor.start().0;
4376        let suffix = match last_transform {
4377            DiffTransform::BufferContent { .. } => {
4378                let end = cursor.start().1 + ExcerptOffset::new(overshoot);
4379                self.text_summary_for_excerpt_offset_range::<D>(cursor.start().1..end)
4380            }
4381            DiffTransform::DeletedHunk {
4382                base_text_byte_range,
4383                buffer_id,
4384                has_trailing_newline,
4385                ..
4386            } => {
4387                let buffer_end = base_text_byte_range.start + overshoot;
4388                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
4389                    panic!("{:?} is in non-existent deleted hunk", range.end)
4390                };
4391
4392                let mut suffix = base_text
4393                    .text_summary_for_range::<D, _>(base_text_byte_range.start..buffer_end);
4394                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
4395                    suffix.add_assign(&D::from_text_summary(&TextSummary::newline()))
4396                }
4397                suffix
4398            }
4399        };
4400
4401        result.add_assign(&suffix);
4402        result
4403    }
4404
4405    fn text_summary_for_excerpt_offset_range<D>(&self, mut range: Range<ExcerptOffset>) -> D
4406    where
4407        D: TextDimension,
4408    {
4409        // let mut range = range.start..range.end;
4410        let mut summary = D::zero(&());
4411        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(&());
4412        cursor.seek(&range.start, Bias::Right, &());
4413        if let Some(excerpt) = cursor.item() {
4414            let mut end_before_newline = cursor.end(&());
4415            if excerpt.has_trailing_newline {
4416                end_before_newline -= ExcerptOffset::new(1);
4417            }
4418
4419            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4420            let start_in_excerpt = excerpt_start + (range.start - *cursor.start()).value;
4421            let end_in_excerpt =
4422                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start()).value;
4423            summary.add_assign(
4424                &excerpt
4425                    .buffer
4426                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
4427            );
4428
4429            if range.end > end_before_newline {
4430                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
4431            }
4432
4433            cursor.next(&());
4434        }
4435
4436        if range.end > *cursor.start() {
4437            summary.add_assign(
4438                &cursor
4439                    .summary::<_, ExcerptDimension<D>>(&range.end, Bias::Right, &())
4440                    .0,
4441            );
4442            if let Some(excerpt) = cursor.item() {
4443                range.end = cmp::max(*cursor.start(), range.end);
4444
4445                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4446                let end_in_excerpt = excerpt_start + (range.end - *cursor.start()).value;
4447                summary.add_assign(
4448                    &excerpt
4449                        .buffer
4450                        .text_summary_for_range(excerpt_start..end_in_excerpt),
4451                );
4452            }
4453        }
4454
4455        summary
4456    }
4457
4458    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
4459    where
4460        D: TextDimension + Ord + Sub<D, Output = D>,
4461    {
4462        self.summaries_for_anchors([anchor])[0]
4463    }
4464
4465    fn resolve_summary_for_anchor<D>(
4466        &self,
4467        anchor: &Anchor,
4468        excerpt_position: D,
4469        diff_transforms: &mut Cursor<DiffTransform, (ExcerptDimension<D>, OutputDimension<D>)>,
4470    ) -> D
4471    where
4472        D: TextDimension + Ord + Sub<D, Output = D>,
4473    {
4474        loop {
4475            let transform_end_position = diff_transforms.end(&()).0 .0;
4476            let at_transform_end =
4477                excerpt_position == transform_end_position && diff_transforms.item().is_some();
4478            if at_transform_end && anchor.text_anchor.bias == Bias::Right {
4479                diff_transforms.next(&());
4480                continue;
4481            }
4482
4483            let mut position = diff_transforms.start().1 .0;
4484            match diff_transforms.item() {
4485                Some(DiffTransform::DeletedHunk {
4486                    buffer_id,
4487                    base_text_byte_range,
4488                    ..
4489                }) => {
4490                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor {
4491                        if let Some(base_text) =
4492                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
4493                        {
4494                            if base_text.can_resolve(&diff_base_anchor) {
4495                                let base_text_offset = diff_base_anchor.to_offset(&base_text);
4496                                if base_text_offset >= base_text_byte_range.start
4497                                    && base_text_offset <= base_text_byte_range.end
4498                                {
4499                                    let position_in_hunk = base_text
4500                                        .text_summary_for_range::<D, _>(
4501                                            base_text_byte_range.start..base_text_offset,
4502                                        );
4503                                    position.add_assign(&position_in_hunk);
4504                                } else if at_transform_end {
4505                                    diff_transforms.next(&());
4506                                    continue;
4507                                }
4508                            }
4509                        }
4510                    }
4511                }
4512                _ => {
4513                    if at_transform_end && anchor.diff_base_anchor.is_some() {
4514                        diff_transforms.next(&());
4515                        continue;
4516                    }
4517                    let overshoot = excerpt_position - diff_transforms.start().0 .0;
4518                    position.add_assign(&overshoot);
4519                }
4520            }
4521
4522            return position;
4523        }
4524    }
4525
4526    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
4527        let mut cursor = self
4528            .excerpts
4529            .cursor::<(Option<&Locator>, ExcerptOffset)>(&());
4530        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
4531
4532        cursor.seek(&Some(locator), Bias::Left, &());
4533        if cursor.item().is_none() {
4534            cursor.next(&());
4535        }
4536
4537        let mut position = cursor.start().1;
4538        if let Some(excerpt) = cursor.item() {
4539            if excerpt.id == anchor.excerpt_id {
4540                let excerpt_buffer_start = excerpt
4541                    .buffer
4542                    .offset_for_anchor(&excerpt.range.context.start);
4543                let excerpt_buffer_end =
4544                    excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
4545                let buffer_position = cmp::min(
4546                    excerpt_buffer_end,
4547                    excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
4548                );
4549                if buffer_position > excerpt_buffer_start {
4550                    position.value += buffer_position - excerpt_buffer_start;
4551                }
4552            }
4553        }
4554        position
4555    }
4556
4557    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
4558    where
4559        D: TextDimension + Ord + Sub<D, Output = D>,
4560        I: 'a + IntoIterator<Item = &'a Anchor>,
4561    {
4562        let mut anchors = anchors.into_iter().peekable();
4563        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
4564        let mut diff_transforms_cursor = self
4565            .diff_transforms
4566            .cursor::<(ExcerptDimension<D>, OutputDimension<D>)>(&());
4567        diff_transforms_cursor.next(&());
4568
4569        let mut summaries = Vec::new();
4570        while let Some(anchor) = anchors.peek() {
4571            let excerpt_id = anchor.excerpt_id;
4572            let excerpt_anchors = iter::from_fn(|| {
4573                let anchor = anchors.peek()?;
4574                if anchor.excerpt_id == excerpt_id {
4575                    Some(anchors.next().unwrap())
4576                } else {
4577                    None
4578                }
4579            });
4580
4581            let locator = self.excerpt_locator_for_id(excerpt_id);
4582            cursor.seek_forward(locator, Bias::Left, &());
4583            if cursor.item().is_none() {
4584                cursor.next(&());
4585            }
4586
4587            let excerpt_start_position = D::from_text_summary(&cursor.start().text);
4588            if let Some(excerpt) = cursor.item() {
4589                if excerpt.id != excerpt_id {
4590                    let position = self.resolve_summary_for_anchor(
4591                        &Anchor::min(),
4592                        excerpt_start_position,
4593                        &mut diff_transforms_cursor,
4594                    );
4595                    summaries.extend(excerpt_anchors.map(|_| position));
4596                    continue;
4597                }
4598                let excerpt_buffer_start =
4599                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
4600                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
4601                for (buffer_summary, anchor) in excerpt
4602                    .buffer
4603                    .summaries_for_anchors_with_payload::<D, _, _>(
4604                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
4605                    )
4606                {
4607                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
4608                    let mut position = excerpt_start_position;
4609                    if summary > excerpt_buffer_start {
4610                        position.add_assign(&(summary - excerpt_buffer_start));
4611                    }
4612
4613                    if position > diff_transforms_cursor.start().0 .0 {
4614                        diff_transforms_cursor.seek_forward(
4615                            &ExcerptDimension(position),
4616                            Bias::Left,
4617                            &(),
4618                        );
4619                    }
4620
4621                    summaries.push(self.resolve_summary_for_anchor(
4622                        anchor,
4623                        position,
4624                        &mut diff_transforms_cursor,
4625                    ));
4626                }
4627            } else {
4628                diff_transforms_cursor.seek_forward(
4629                    &ExcerptDimension(excerpt_start_position),
4630                    Bias::Left,
4631                    &(),
4632                );
4633                let position = self.resolve_summary_for_anchor(
4634                    &Anchor::max(),
4635                    excerpt_start_position,
4636                    &mut diff_transforms_cursor,
4637                );
4638                summaries.extend(excerpt_anchors.map(|_| position));
4639            }
4640        }
4641
4642        summaries
4643    }
4644
4645    pub fn dimensions_from_points<'a, D>(
4646        &'a self,
4647        points: impl 'a + IntoIterator<Item = Point>,
4648    ) -> impl 'a + Iterator<Item = D>
4649    where
4650        D: TextDimension + Sub<D, Output = D>,
4651    {
4652        let mut cursor = self.cursor::<DimensionPair<Point, D>>();
4653        cursor.seek(&DimensionPair {
4654            key: Point::default(),
4655            value: None,
4656        });
4657        let mut points = points.into_iter();
4658        iter::from_fn(move || {
4659            let point = points.next()?;
4660
4661            cursor.seek_forward(&DimensionPair {
4662                key: point,
4663                value: None,
4664            });
4665
4666            if let Some(region) = cursor.region() {
4667                let overshoot = point - region.range.start.key;
4668                let buffer_point = region.buffer_range.start.key + overshoot;
4669                let mut position = region.range.start.value.unwrap();
4670                position.add_assign(
4671                    &region
4672                        .buffer
4673                        .text_summary_for_range(region.buffer_range.start.key..buffer_point),
4674                );
4675                return Some(position);
4676            } else {
4677                return Some(D::from_text_summary(&self.text_summary()));
4678            }
4679        })
4680    }
4681
4682    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
4683    where
4684        I: 'a + IntoIterator<Item = &'a Anchor>,
4685    {
4686        let mut anchors = anchors.into_iter().enumerate().peekable();
4687        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
4688        cursor.next(&());
4689
4690        let mut result = Vec::new();
4691
4692        while let Some((_, anchor)) = anchors.peek() {
4693            let old_excerpt_id = anchor.excerpt_id;
4694
4695            // Find the location where this anchor's excerpt should be.
4696            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
4697            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
4698
4699            if cursor.item().is_none() {
4700                cursor.next(&());
4701            }
4702
4703            let next_excerpt = cursor.item();
4704            let prev_excerpt = cursor.prev_item();
4705
4706            // Process all of the anchors for this excerpt.
4707            while let Some((_, anchor)) = anchors.peek() {
4708                if anchor.excerpt_id != old_excerpt_id {
4709                    break;
4710                }
4711                let (anchor_ix, anchor) = anchors.next().unwrap();
4712                let mut anchor = *anchor;
4713
4714                // Leave min and max anchors unchanged if invalid or
4715                // if the old excerpt still exists at this location
4716                let mut kept_position = next_excerpt
4717                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
4718                    || old_excerpt_id == ExcerptId::max()
4719                    || old_excerpt_id == ExcerptId::min();
4720
4721                // If the old excerpt no longer exists at this location, then attempt to
4722                // find an equivalent position for this anchor in an adjacent excerpt.
4723                if !kept_position {
4724                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
4725                        if excerpt.contains(&anchor) {
4726                            anchor.excerpt_id = excerpt.id;
4727                            kept_position = true;
4728                            break;
4729                        }
4730                    }
4731                }
4732
4733                // If there's no adjacent excerpt that contains the anchor's position,
4734                // then report that the anchor has lost its position.
4735                if !kept_position {
4736                    anchor = if let Some(excerpt) = next_excerpt {
4737                        let mut text_anchor = excerpt
4738                            .range
4739                            .context
4740                            .start
4741                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
4742                        if text_anchor
4743                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
4744                            .is_gt()
4745                        {
4746                            text_anchor = excerpt.range.context.end;
4747                        }
4748                        Anchor {
4749                            buffer_id: Some(excerpt.buffer_id),
4750                            excerpt_id: excerpt.id,
4751                            text_anchor,
4752                            diff_base_anchor: None,
4753                        }
4754                    } else if let Some(excerpt) = prev_excerpt {
4755                        let mut text_anchor = excerpt
4756                            .range
4757                            .context
4758                            .end
4759                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
4760                        if text_anchor
4761                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
4762                            .is_lt()
4763                        {
4764                            text_anchor = excerpt.range.context.start;
4765                        }
4766                        Anchor {
4767                            buffer_id: Some(excerpt.buffer_id),
4768                            excerpt_id: excerpt.id,
4769                            text_anchor,
4770                            diff_base_anchor: None,
4771                        }
4772                    } else if anchor.text_anchor.bias == Bias::Left {
4773                        Anchor::min()
4774                    } else {
4775                        Anchor::max()
4776                    };
4777                }
4778
4779                result.push((anchor_ix, anchor, kept_position));
4780            }
4781        }
4782        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
4783        result
4784    }
4785
4786    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
4787        self.anchor_at(position, Bias::Left)
4788    }
4789
4790    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
4791        self.anchor_at(position, Bias::Right)
4792    }
4793
4794    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
4795        let offset = position.to_offset(self);
4796
4797        // Find the given position in the diff transforms. Determine the corresponding
4798        // offset in the excerpts, and whether the position is within a deleted hunk.
4799        let mut diff_transforms = self.diff_transforms.cursor::<(usize, ExcerptOffset)>(&());
4800        diff_transforms.seek(&offset, Bias::Right, &());
4801
4802        if offset == diff_transforms.start().0 && bias == Bias::Left {
4803            if let Some(prev_item) = diff_transforms.prev_item() {
4804                match prev_item {
4805                    DiffTransform::DeletedHunk { .. } => {
4806                        diff_transforms.prev(&());
4807                    }
4808                    _ => {}
4809                }
4810            }
4811        }
4812        let offset_in_transform = offset - diff_transforms.start().0;
4813        let mut excerpt_offset = diff_transforms.start().1;
4814        let mut diff_base_anchor = None;
4815        if let Some(DiffTransform::DeletedHunk {
4816            buffer_id,
4817            base_text_byte_range,
4818            has_trailing_newline,
4819            ..
4820        }) = diff_transforms.item()
4821        {
4822            let diff = self.diffs.get(buffer_id).expect("missing diff");
4823            if offset_in_transform > base_text_byte_range.len() {
4824                debug_assert!(*has_trailing_newline);
4825                bias = Bias::Right;
4826            } else {
4827                diff_base_anchor = Some(
4828                    diff.base_text()
4829                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
4830                );
4831                bias = Bias::Left;
4832            }
4833        } else {
4834            excerpt_offset += ExcerptOffset::new(offset_in_transform);
4835        };
4836
4837        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
4838            return Anchor {
4839                buffer_id: Some(buffer_id),
4840                excerpt_id: *excerpt_id,
4841                text_anchor: buffer.anchor_at(excerpt_offset.value, bias),
4842                diff_base_anchor,
4843            };
4844        }
4845
4846        let mut excerpts = self
4847            .excerpts
4848            .cursor::<(ExcerptOffset, Option<ExcerptId>)>(&());
4849        excerpts.seek(&excerpt_offset, Bias::Right, &());
4850        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
4851            excerpts.prev(&());
4852        }
4853        if let Some(excerpt) = excerpts.item() {
4854            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0).value;
4855            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end(&()).0 {
4856                overshoot -= 1;
4857                bias = Bias::Right;
4858            }
4859
4860            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4861            let text_anchor =
4862                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
4863            Anchor {
4864                buffer_id: Some(excerpt.buffer_id),
4865                excerpt_id: excerpt.id,
4866                text_anchor,
4867                diff_base_anchor,
4868            }
4869        } else if excerpt_offset.is_zero() && bias == Bias::Left {
4870            Anchor::min()
4871        } else {
4872            Anchor::max()
4873        }
4874    }
4875
4876    /// Returns an anchor for the given excerpt and text anchor,
4877    /// returns None if the excerpt_id is no longer valid.
4878    pub fn anchor_in_excerpt(
4879        &self,
4880        excerpt_id: ExcerptId,
4881        text_anchor: text::Anchor,
4882    ) -> Option<Anchor> {
4883        let locator = self.excerpt_locator_for_id(excerpt_id);
4884        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
4885        cursor.seek(locator, Bias::Left, &());
4886        if let Some(excerpt) = cursor.item() {
4887            if excerpt.id == excerpt_id {
4888                let text_anchor = excerpt.clip_anchor(text_anchor);
4889                drop(cursor);
4890                return Some(Anchor {
4891                    buffer_id: Some(excerpt.buffer_id),
4892                    excerpt_id,
4893                    text_anchor,
4894                    diff_base_anchor: None,
4895                });
4896            }
4897        }
4898        None
4899    }
4900
4901    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
4902        Some(self.excerpt(excerpt_id)?.range.context.clone())
4903    }
4904
4905    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
4906        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
4907            true
4908        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
4909            excerpt.buffer.can_resolve(&anchor.text_anchor)
4910        } else {
4911            false
4912        }
4913    }
4914
4915    pub fn excerpts(
4916        &self,
4917    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
4918        self.excerpts
4919            .iter()
4920            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
4921    }
4922
4923    fn cursor<D: TextDimension + Default>(&self) -> MultiBufferCursor<D> {
4924        let excerpts = self.excerpts.cursor(&());
4925        let diff_transforms = self.diff_transforms.cursor(&());
4926        MultiBufferCursor {
4927            excerpts,
4928            diff_transforms,
4929            diffs: &self.diffs,
4930            cached_region: None,
4931        }
4932    }
4933
4934    pub fn excerpt_before(&self, id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
4935        let start_locator = self.excerpt_locator_for_id(id);
4936        let mut excerpts = self
4937            .excerpts
4938            .cursor::<(Option<&Locator>, ExcerptDimension<usize>)>(&());
4939        excerpts.seek(&Some(start_locator), Bias::Left, &());
4940        excerpts.prev(&());
4941
4942        let mut diff_transforms = self
4943            .diff_transforms
4944            .cursor::<(OutputDimension<usize>, ExcerptDimension<usize>)>(&());
4945        diff_transforms.seek(&excerpts.start().1, Bias::Left, &());
4946        if diff_transforms.end(&()).1 < excerpts.start().1 {
4947            diff_transforms.next(&());
4948        }
4949
4950        let excerpt = excerpts.item()?;
4951        Some(MultiBufferExcerpt {
4952            excerpt,
4953            offset: diff_transforms.start().0 .0,
4954            buffer_offset: excerpt.range.context.start.to_offset(&excerpt.buffer),
4955            excerpt_offset: excerpts.start().1.clone(),
4956            diff_transforms,
4957        })
4958    }
4959
4960    pub fn excerpt_boundaries_in_range<R, T>(
4961        &self,
4962        range: R,
4963    ) -> impl Iterator<Item = ExcerptBoundary> + '_
4964    where
4965        R: RangeBounds<T>,
4966        T: ToOffset,
4967    {
4968        let start_offset;
4969        let start = match range.start_bound() {
4970            Bound::Included(start) => {
4971                start_offset = start.to_offset(self);
4972                Bound::Included(start_offset)
4973            }
4974            Bound::Excluded(_) => {
4975                panic!("not supported")
4976            }
4977            Bound::Unbounded => {
4978                start_offset = 0;
4979                Bound::Unbounded
4980            }
4981        };
4982        let end = match range.end_bound() {
4983            Bound::Included(end) => Bound::Included(end.to_offset(self)),
4984            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
4985            Bound::Unbounded => Bound::Unbounded,
4986        };
4987        let bounds = (start, end);
4988
4989        let mut cursor = self.cursor::<DimensionPair<usize, Point>>();
4990        cursor.seek(&DimensionPair {
4991            key: start_offset,
4992            value: None,
4993        });
4994
4995        if cursor
4996            .region()
4997            .is_some_and(|region| bounds.contains(&region.range.start.key))
4998        {
4999            cursor.prev_excerpt();
5000        } else {
5001            cursor.seek_to_start_of_current_excerpt();
5002        }
5003        let mut prev_region = cursor.region();
5004
5005        cursor.next_excerpt();
5006
5007        let mut visited_end = false;
5008        iter::from_fn(move || loop {
5009            if self.singleton {
5010                return None;
5011            }
5012
5013            let next_region = cursor.region();
5014            cursor.next_excerpt();
5015
5016            let next_region_start = if let Some(region) = &next_region {
5017                if !bounds.contains(&region.range.start.key) {
5018                    prev_region = next_region;
5019                    continue;
5020                }
5021                region.range.start.value.unwrap()
5022            } else {
5023                if !bounds.contains(&self.len()) {
5024                    return None;
5025                }
5026                self.max_point()
5027            };
5028            let next_region_end = if let Some(region) = cursor.region() {
5029                region.range.start.value.unwrap()
5030            } else {
5031                self.max_point()
5032            };
5033
5034            let prev = prev_region.as_ref().map(|region| ExcerptInfo {
5035                id: region.excerpt.id,
5036                buffer: region.excerpt.buffer.clone(),
5037                buffer_id: region.excerpt.buffer_id,
5038                range: region.excerpt.range.clone(),
5039                end_row: MultiBufferRow(next_region_start.row),
5040            });
5041
5042            let next = next_region.as_ref().map(|region| ExcerptInfo {
5043                id: region.excerpt.id,
5044                buffer: region.excerpt.buffer.clone(),
5045                buffer_id: region.excerpt.buffer_id,
5046                range: region.excerpt.range.clone(),
5047                end_row: if region.excerpt.has_trailing_newline {
5048                    MultiBufferRow(next_region_end.row - 1)
5049                } else {
5050                    MultiBufferRow(next_region_end.row)
5051                },
5052            });
5053
5054            if next.is_none() {
5055                if visited_end {
5056                    return None;
5057                } else {
5058                    visited_end = true;
5059                }
5060            }
5061
5062            let row = MultiBufferRow(next_region_start.row);
5063
5064            prev_region = next_region;
5065
5066            return Some(ExcerptBoundary { row, prev, next });
5067        })
5068    }
5069
5070    pub fn edit_count(&self) -> usize {
5071        self.edit_count
5072    }
5073
5074    pub fn non_text_state_update_count(&self) -> usize {
5075        self.non_text_state_update_count
5076    }
5077
5078    /// Returns the smallest enclosing bracket ranges containing the given range or
5079    /// None if no brackets contain range or the range is not contained in a single
5080    /// excerpt
5081    ///
5082    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
5083    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
5084        &self,
5085        range: Range<T>,
5086        range_filter: Option<&dyn Fn(&BufferSnapshot, Range<usize>, Range<usize>) -> bool>,
5087    ) -> Option<(Range<usize>, Range<usize>)> {
5088        let range = range.start.to_offset(self)..range.end.to_offset(self);
5089        let mut excerpt = self.excerpt_containing(range.clone())?;
5090        let buffer = excerpt.buffer();
5091        let excerpt_buffer_range = excerpt.buffer_range();
5092
5093        // Filter to ranges contained in the excerpt
5094        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
5095            excerpt_buffer_range.contains(&open.start)
5096                && excerpt_buffer_range.contains(&close.end)
5097                && range_filter.map_or(true, |filter| filter(buffer, open, close))
5098        };
5099
5100        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
5101            excerpt.map_range_to_buffer(range),
5102            Some(&range_filter),
5103        )?;
5104
5105        Some((
5106            excerpt.map_range_from_buffer(open),
5107            excerpt.map_range_from_buffer(close),
5108        ))
5109    }
5110
5111    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5112    /// not contained in a single excerpt
5113    pub fn enclosing_bracket_ranges<T: ToOffset>(
5114        &self,
5115        range: Range<T>,
5116    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5117        let range = range.start.to_offset(self)..range.end.to_offset(self);
5118        let mut excerpt = self.excerpt_containing(range.clone())?;
5119
5120        Some(
5121            excerpt
5122                .buffer()
5123                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
5124                .filter_map(move |pair| {
5125                    if excerpt.contains_buffer_range(pair.open_range.start..pair.close_range.end) {
5126                        Some((
5127                            excerpt.map_range_from_buffer(pair.open_range),
5128                            excerpt.map_range_from_buffer(pair.close_range),
5129                        ))
5130                    } else {
5131                        None
5132                    }
5133                }),
5134        )
5135    }
5136
5137    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
5138    /// not contained in a single excerpt
5139    pub fn text_object_ranges<T: ToOffset>(
5140        &self,
5141        range: Range<T>,
5142        options: TreeSitterOptions,
5143    ) -> impl Iterator<Item = (Range<usize>, TextObject)> + '_ {
5144        let range = range.start.to_offset(self)..range.end.to_offset(self);
5145        self.excerpt_containing(range.clone())
5146            .map(|mut excerpt| {
5147                excerpt
5148                    .buffer()
5149                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
5150                    .filter_map(move |(range, text_object)| {
5151                        if excerpt.contains_buffer_range(range.clone()) {
5152                            Some((excerpt.map_range_from_buffer(range), text_object))
5153                        } else {
5154                            None
5155                        }
5156                    })
5157            })
5158            .into_iter()
5159            .flatten()
5160    }
5161
5162    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
5163    /// not contained in a single excerpt
5164    pub fn bracket_ranges<T: ToOffset>(
5165        &self,
5166        range: Range<T>,
5167    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
5168        let range = range.start.to_offset(self)..range.end.to_offset(self);
5169        let mut excerpt = self.excerpt_containing(range.clone())?;
5170
5171        Some(
5172            excerpt
5173                .buffer()
5174                .bracket_ranges(excerpt.map_range_to_buffer(range))
5175                .filter_map(move |pair| {
5176                    let buffer_range = pair.open_range.start..pair.close_range.end;
5177                    if excerpt.contains_buffer_range(buffer_range) {
5178                        Some((
5179                            excerpt.map_range_from_buffer(pair.open_range),
5180                            excerpt.map_range_from_buffer(pair.close_range),
5181                        ))
5182                    } else {
5183                        None
5184                    }
5185                }),
5186        )
5187    }
5188
5189    pub fn redacted_ranges<'a, T: ToOffset>(
5190        &'a self,
5191        range: Range<T>,
5192        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
5193    ) -> impl Iterator<Item = Range<usize>> + 'a {
5194        let range = range.start.to_offset(self)..range.end.to_offset(self);
5195        self.lift_buffer_metadata(range, move |buffer, range| {
5196            if redaction_enabled(buffer.file()) {
5197                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
5198            } else {
5199                None
5200            }
5201        })
5202        .map(|(range, _, _)| range)
5203    }
5204
5205    pub fn runnable_ranges(
5206        &self,
5207        range: Range<Anchor>,
5208    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
5209        let range = range.start.to_offset(self)..range.end.to_offset(self);
5210        self.lift_buffer_metadata(range, move |buffer, range| {
5211            Some(
5212                buffer
5213                    .runnable_ranges(range.clone())
5214                    .filter(move |runnable| {
5215                        runnable.run_range.start >= range.start
5216                            && runnable.run_range.end < range.end
5217                    })
5218                    .map(|runnable| (runnable.run_range.clone(), runnable)),
5219            )
5220        })
5221        .map(|(run_range, runnable, _)| language::RunnableRange {
5222            run_range,
5223            ..runnable
5224        })
5225    }
5226
5227    pub fn line_indents(
5228        &self,
5229        start_row: MultiBufferRow,
5230        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5231    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5232        let max_point = self.max_point();
5233        let mut cursor = self.cursor::<Point>();
5234        cursor.seek(&Point::new(start_row.0, 0));
5235        iter::from_fn(move || {
5236            let mut region = cursor.region()?;
5237            while !buffer_filter(&region.excerpt.buffer) {
5238                cursor.next();
5239                region = cursor.region()?;
5240            }
5241            let overshoot = start_row.0.saturating_sub(region.range.start.row);
5242            let buffer_start_row =
5243                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
5244
5245            let buffer_end_row = if region.is_main_buffer
5246                && (region.has_trailing_newline || region.range.end == max_point)
5247            {
5248                region.buffer_range.end.row
5249            } else {
5250                region.buffer_range.end.row.saturating_sub(1)
5251            };
5252
5253            let line_indents = region
5254                .buffer
5255                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
5256            cursor.next();
5257            return Some(line_indents.map(move |(buffer_row, indent)| {
5258                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5259                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5260            }));
5261        })
5262        .flatten()
5263    }
5264
5265    pub fn reversed_line_indents(
5266        &self,
5267        end_row: MultiBufferRow,
5268        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
5269    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
5270        let max_point = self.max_point();
5271        let mut cursor = self.cursor::<Point>();
5272        cursor.seek(&Point::new(end_row.0, 0));
5273        iter::from_fn(move || {
5274            let mut region = cursor.region()?;
5275            while !buffer_filter(&region.excerpt.buffer) {
5276                cursor.prev();
5277                region = cursor.region()?;
5278            }
5279
5280            let buffer_start_row = region.buffer_range.start.row;
5281            let buffer_end_row = if region.is_main_buffer
5282                && (region.has_trailing_newline || region.range.end == max_point)
5283            {
5284                region.buffer_range.end.row + 1
5285            } else {
5286                region.buffer_range.end.row
5287            };
5288
5289            let overshoot = end_row.0 - region.range.start.row;
5290            let buffer_end_row =
5291                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
5292
5293            let line_indents = region
5294                .buffer
5295                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
5296            cursor.prev();
5297            return Some(line_indents.map(move |(buffer_row, indent)| {
5298                let row = region.range.start.row + (buffer_row - region.buffer_range.start.row);
5299                (MultiBufferRow(row), indent, &region.excerpt.buffer)
5300            }));
5301        })
5302        .flatten()
5303    }
5304
5305    pub async fn enclosing_indent(
5306        &self,
5307        mut target_row: MultiBufferRow,
5308    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
5309        let max_row = MultiBufferRow(self.max_point().row);
5310        if target_row >= max_row {
5311            return None;
5312        }
5313
5314        let mut target_indent = self.line_indent_for_row(target_row);
5315
5316        // If the current row is at the start of an indented block, we want to return this
5317        // block as the enclosing indent.
5318        if !target_indent.is_line_empty() && target_row < max_row {
5319            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
5320            if !next_line_indent.is_line_empty()
5321                && target_indent.raw_len() < next_line_indent.raw_len()
5322            {
5323                target_indent = next_line_indent;
5324                target_row.0 += 1;
5325            }
5326        }
5327
5328        const SEARCH_ROW_LIMIT: u32 = 25000;
5329        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
5330        const YIELD_INTERVAL: u32 = 100;
5331
5332        let mut accessed_row_counter = 0;
5333
5334        // If there is a blank line at the current row, search for the next non indented lines
5335        if target_indent.is_line_empty() {
5336            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
5337            let end =
5338                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
5339
5340            let mut non_empty_line_above = None;
5341            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5342                if row < start {
5343                    break;
5344                }
5345                accessed_row_counter += 1;
5346                if accessed_row_counter == YIELD_INTERVAL {
5347                    accessed_row_counter = 0;
5348                    yield_now().await;
5349                }
5350                if !indent.is_line_empty() {
5351                    non_empty_line_above = Some((row, indent));
5352                    break;
5353                }
5354            }
5355
5356            let mut non_empty_line_below = None;
5357            for (row, indent, _) in self.line_indents(target_row, |_| true) {
5358                if row > end {
5359                    break;
5360                }
5361                accessed_row_counter += 1;
5362                if accessed_row_counter == YIELD_INTERVAL {
5363                    accessed_row_counter = 0;
5364                    yield_now().await;
5365                }
5366                if !indent.is_line_empty() {
5367                    non_empty_line_below = Some((row, indent));
5368                    break;
5369                }
5370            }
5371
5372            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
5373                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
5374                    if above_indent.raw_len() >= below_indent.raw_len() {
5375                        (above_row, above_indent)
5376                    } else {
5377                        (below_row, below_indent)
5378                    }
5379                }
5380                (Some(above), None) => above,
5381                (None, Some(below)) => below,
5382                _ => return None,
5383            };
5384
5385            target_indent = indent;
5386            target_row = row;
5387        }
5388
5389        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
5390        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
5391
5392        let mut start_indent = None;
5393        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
5394            if row < start {
5395                break;
5396            }
5397            accessed_row_counter += 1;
5398            if accessed_row_counter == YIELD_INTERVAL {
5399                accessed_row_counter = 0;
5400                yield_now().await;
5401            }
5402            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5403                start_indent = Some((row, indent));
5404                break;
5405            }
5406        }
5407        let (start_row, start_indent_size) = start_indent?;
5408
5409        let mut end_indent = (end, None);
5410        for (row, indent, _) in self.line_indents(target_row, |_| true) {
5411            if row > end {
5412                break;
5413            }
5414            accessed_row_counter += 1;
5415            if accessed_row_counter == YIELD_INTERVAL {
5416                accessed_row_counter = 0;
5417                yield_now().await;
5418            }
5419            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
5420                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
5421                break;
5422            }
5423        }
5424        let (end_row, end_indent_size) = end_indent;
5425
5426        let indent = if let Some(end_indent_size) = end_indent_size {
5427            if start_indent_size.raw_len() > end_indent_size.raw_len() {
5428                start_indent_size
5429            } else {
5430                end_indent_size
5431            }
5432        } else {
5433            start_indent_size
5434        };
5435
5436        Some((start_row..end_row, indent))
5437    }
5438
5439    pub fn indent_guides_in_range<T: ToPoint>(
5440        &self,
5441        range: Range<T>,
5442        ignore_disabled_for_language: bool,
5443        cx: &App,
5444    ) -> impl Iterator<Item = IndentGuide> {
5445        let range = range.start.to_point(self)..range.end.to_point(self);
5446        let start_row = MultiBufferRow(range.start.row);
5447        let end_row = MultiBufferRow(range.end.row);
5448
5449        let mut row_indents = self.line_indents(start_row, |buffer| {
5450            let settings =
5451                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5452            settings.indent_guides.enabled || ignore_disabled_for_language
5453        });
5454
5455        let mut result = Vec::new();
5456        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
5457
5458        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
5459            if first_row > end_row {
5460                break;
5461            }
5462            let current_depth = indent_stack.len() as u32;
5463
5464            let settings =
5465                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
5466            let tab_size = settings.tab_size.get() as u32;
5467
5468            // When encountering empty, continue until found useful line indent
5469            // then add to the indent stack with the depth found
5470            let mut found_indent = false;
5471            let mut last_row = first_row;
5472            if line_indent.is_line_empty() {
5473                while !found_indent {
5474                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
5475                        break;
5476                    };
5477                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
5478                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
5479                        break;
5480                    }
5481
5482                    if new_line_indent.is_line_empty() {
5483                        continue;
5484                    }
5485                    last_row = target_row.min(end_row);
5486                    line_indent = new_line_indent;
5487                    found_indent = true;
5488                    break;
5489                }
5490            } else {
5491                found_indent = true
5492            }
5493
5494            let depth = if found_indent {
5495                line_indent.len(tab_size) / tab_size
5496                    + ((line_indent.len(tab_size) % tab_size) > 0) as u32
5497            } else {
5498                current_depth
5499            };
5500
5501            match depth.cmp(&current_depth) {
5502                cmp::Ordering::Less => {
5503                    for _ in 0..(current_depth - depth) {
5504                        let mut indent = indent_stack.pop().unwrap();
5505                        if last_row != first_row {
5506                            // In this case, we landed on an empty row, had to seek forward,
5507                            // and discovered that the indent we where on is ending.
5508                            // This means that the last display row must
5509                            // be on line that ends this indent range, so we
5510                            // should display the range up to the first non-empty line
5511                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
5512                        }
5513
5514                        result.push(indent)
5515                    }
5516                }
5517                cmp::Ordering::Greater => {
5518                    for next_depth in current_depth..depth {
5519                        indent_stack.push(IndentGuide {
5520                            buffer_id: buffer.remote_id(),
5521                            start_row: first_row,
5522                            end_row: last_row,
5523                            depth: next_depth,
5524                            tab_size,
5525                            settings: settings.indent_guides,
5526                        });
5527                    }
5528                }
5529                _ => {}
5530            }
5531
5532            for indent in indent_stack.iter_mut() {
5533                indent.end_row = last_row;
5534            }
5535        }
5536
5537        result.extend(indent_stack);
5538        result.into_iter()
5539    }
5540
5541    pub fn trailing_excerpt_update_count(&self) -> usize {
5542        self.trailing_excerpt_update_count
5543    }
5544
5545    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
5546        self.point_to_buffer_offset(point)
5547            .and_then(|(buffer, _)| buffer.file())
5548    }
5549
5550    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
5551        self.point_to_buffer_offset(point)
5552            .and_then(|(buffer, offset)| buffer.language_at(offset))
5553    }
5554
5555    pub fn settings_at<'a, T: ToOffset>(
5556        &'a self,
5557        point: T,
5558        cx: &'a App,
5559    ) -> Cow<'a, LanguageSettings> {
5560        let mut language = None;
5561        let mut file = None;
5562        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
5563            language = buffer.language_at(offset);
5564            file = buffer.file();
5565        }
5566        language_settings(language.map(|l| l.name()), file, cx)
5567    }
5568
5569    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
5570        self.point_to_buffer_offset(point)
5571            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
5572    }
5573
5574    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
5575        self.point_to_buffer_offset(point)
5576            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
5577            .unwrap_or_default()
5578    }
5579
5580    pub fn language_indent_size_at<T: ToOffset>(
5581        &self,
5582        position: T,
5583        cx: &App,
5584    ) -> Option<IndentSize> {
5585        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
5586        Some(buffer_snapshot.language_indent_size_at(offset, cx))
5587    }
5588
5589    pub fn is_dirty(&self) -> bool {
5590        self.is_dirty
5591    }
5592
5593    pub fn has_deleted_file(&self) -> bool {
5594        self.has_deleted_file
5595    }
5596
5597    pub fn has_conflict(&self) -> bool {
5598        self.has_conflict
5599    }
5600
5601    pub fn has_diagnostics(&self) -> bool {
5602        self.excerpts
5603            .iter()
5604            .any(|excerpt| excerpt.buffer.has_diagnostics())
5605    }
5606
5607    pub fn diagnostic_group(
5608        &self,
5609        buffer_id: BufferId,
5610        group_id: usize,
5611    ) -> impl Iterator<Item = DiagnosticEntry<Point>> + '_ {
5612        self.lift_buffer_metadata(Point::zero()..self.max_point(), move |buffer, _| {
5613            if buffer.remote_id() != buffer_id {
5614                return None;
5615            };
5616            Some(
5617                buffer
5618                    .diagnostic_group(group_id)
5619                    .map(move |DiagnosticEntry { diagnostic, range }| (range, diagnostic)),
5620            )
5621        })
5622        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
5623    }
5624
5625    pub fn diagnostics_in_range<'a, T>(
5626        &'a self,
5627        range: Range<T>,
5628    ) -> impl Iterator<Item = DiagnosticEntry<T>> + 'a
5629    where
5630        T: 'a
5631            + text::ToOffset
5632            + text::FromAnchor
5633            + TextDimension
5634            + Ord
5635            + Sub<T, Output = T>
5636            + fmt::Debug,
5637    {
5638        self.lift_buffer_metadata(range, move |buffer, buffer_range| {
5639            Some(
5640                buffer
5641                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
5642                    .map(|entry| (entry.range, entry.diagnostic)),
5643            )
5644        })
5645        .map(|(range, diagnostic, _)| DiagnosticEntry { diagnostic, range })
5646    }
5647
5648    pub fn syntax_ancestor<T: ToOffset>(
5649        &self,
5650        range: Range<T>,
5651    ) -> Option<(tree_sitter::Node, MultiOrSingleBufferOffsetRange)> {
5652        let range = range.start.to_offset(self)..range.end.to_offset(self);
5653        let mut excerpt = self.excerpt_containing(range.clone())?;
5654        let node = excerpt
5655            .buffer()
5656            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
5657        let node_range = node.byte_range();
5658        let range = if excerpt.contains_buffer_range(node_range.clone()) {
5659            MultiOrSingleBufferOffsetRange::Multi(excerpt.map_range_from_buffer(node_range))
5660        } else {
5661            MultiOrSingleBufferOffsetRange::Single(node_range)
5662        };
5663        Some((node, range))
5664    }
5665
5666    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
5667        let (excerpt_id, _, buffer) = self.as_singleton()?;
5668        let outline = buffer.outline(theme)?;
5669        Some(Outline::new(
5670            outline
5671                .items
5672                .into_iter()
5673                .flat_map(|item| {
5674                    Some(OutlineItem {
5675                        depth: item.depth,
5676                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
5677                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
5678                        text: item.text,
5679                        highlight_ranges: item.highlight_ranges,
5680                        name_ranges: item.name_ranges,
5681                        body_range: item.body_range.and_then(|body_range| {
5682                            Some(
5683                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
5684                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
5685                            )
5686                        }),
5687                        annotation_range: item.annotation_range.and_then(|annotation_range| {
5688                            Some(
5689                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
5690                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
5691                            )
5692                        }),
5693                    })
5694                })
5695                .collect(),
5696        ))
5697    }
5698
5699    pub fn symbols_containing<T: ToOffset>(
5700        &self,
5701        offset: T,
5702        theme: Option<&SyntaxTheme>,
5703    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
5704        let anchor = self.anchor_before(offset);
5705        let excerpt_id = anchor.excerpt_id;
5706        let excerpt = self.excerpt(excerpt_id)?;
5707        Some((
5708            excerpt.buffer_id,
5709            excerpt
5710                .buffer
5711                .symbols_containing(anchor.text_anchor, theme)
5712                .into_iter()
5713                .flatten()
5714                .flat_map(|item| {
5715                    Some(OutlineItem {
5716                        depth: item.depth,
5717                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
5718                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
5719                        text: item.text,
5720                        highlight_ranges: item.highlight_ranges,
5721                        name_ranges: item.name_ranges,
5722                        body_range: item.body_range.and_then(|body_range| {
5723                            Some(
5724                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
5725                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
5726                            )
5727                        }),
5728                        annotation_range: item.annotation_range.and_then(|body_range| {
5729                            Some(
5730                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
5731                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
5732                            )
5733                        }),
5734                    })
5735                })
5736                .collect(),
5737        ))
5738    }
5739
5740    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
5741        if id == ExcerptId::min() {
5742            Locator::min_ref()
5743        } else if id == ExcerptId::max() {
5744            Locator::max_ref()
5745        } else {
5746            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
5747            cursor.seek(&id, Bias::Left, &());
5748            if let Some(entry) = cursor.item() {
5749                if entry.id == id {
5750                    return &entry.locator;
5751                }
5752            }
5753            panic!("invalid excerpt id {:?}", id)
5754        }
5755    }
5756
5757    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
5758    fn excerpt_locators_for_ids(
5759        &self,
5760        ids: impl IntoIterator<Item = ExcerptId>,
5761    ) -> SmallVec<[Locator; 1]> {
5762        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
5763        sorted_ids.sort_unstable();
5764        let mut locators = SmallVec::new();
5765
5766        while sorted_ids.last() == Some(&ExcerptId::max()) {
5767            sorted_ids.pop();
5768            if let Some(mapping) = self.excerpt_ids.last() {
5769                locators.push(mapping.locator.clone());
5770            }
5771        }
5772
5773        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
5774        if sorted_ids.peek() == Some(&ExcerptId::min()) {
5775            sorted_ids.next();
5776            if let Some(mapping) = self.excerpt_ids.first() {
5777                locators.push(mapping.locator.clone());
5778            }
5779        }
5780
5781        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
5782        for id in sorted_ids {
5783            if cursor.seek_forward(&id, Bias::Left, &()) {
5784                locators.push(cursor.item().unwrap().locator.clone());
5785            } else {
5786                panic!("invalid excerpt id {:?}", id);
5787            }
5788        }
5789
5790        locators.sort_unstable();
5791        locators
5792    }
5793
5794    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
5795        Some(self.excerpt(excerpt_id)?.buffer_id)
5796    }
5797
5798    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
5799        Some(&self.excerpt(excerpt_id)?.buffer)
5800    }
5801
5802    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
5803        let mut cursor = self
5804            .excerpts
5805            .cursor::<(Option<&Locator>, ExcerptDimension<Point>)>(&());
5806        let locator = self.excerpt_locator_for_id(excerpt_id);
5807        if cursor.seek(&Some(locator), Bias::Left, &()) {
5808            let start = cursor.start().1.clone();
5809            let end = cursor.end(&()).1;
5810            let mut diff_transforms = self
5811                .diff_transforms
5812                .cursor::<(ExcerptDimension<Point>, OutputDimension<Point>)>(&());
5813            diff_transforms.seek(&start, Bias::Left, &());
5814            let overshoot = start.0 - diff_transforms.start().0 .0;
5815            let start = diff_transforms.start().1 .0 + overshoot;
5816            diff_transforms.seek(&end, Bias::Right, &());
5817            let overshoot = end.0 - diff_transforms.start().0 .0;
5818            let end = diff_transforms.start().1 .0 + overshoot;
5819            Some(start..end)
5820        } else {
5821            None
5822        }
5823    }
5824
5825    pub fn buffer_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
5826        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
5827        let locator = self.excerpt_locator_for_id(excerpt_id);
5828        if cursor.seek(&Some(locator), Bias::Left, &()) {
5829            if let Some(excerpt) = cursor.item() {
5830                return Some(excerpt.range.context.clone());
5831            }
5832        }
5833        None
5834    }
5835
5836    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
5837        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
5838        let locator = self.excerpt_locator_for_id(excerpt_id);
5839        cursor.seek(&Some(locator), Bias::Left, &());
5840        if let Some(excerpt) = cursor.item() {
5841            if excerpt.id == excerpt_id {
5842                return Some(excerpt);
5843            }
5844        }
5845        None
5846    }
5847
5848    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
5849    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
5850        let range = range.start.to_offset(self)..range.end.to_offset(self);
5851        let mut cursor = self.cursor::<usize>();
5852        cursor.seek(&range.start);
5853
5854        let start_excerpt = cursor.excerpt()?;
5855        if range.end != range.start {
5856            cursor.seek_forward(&range.end);
5857            if cursor.excerpt()?.id != start_excerpt.id {
5858                return None;
5859            }
5860        }
5861
5862        cursor.seek_to_start_of_current_excerpt();
5863        let region = cursor.region()?;
5864        let offset = region.range.start;
5865        let buffer_offset = region.buffer_range.start;
5866        let excerpt_offset = cursor.excerpts.start().clone();
5867        Some(MultiBufferExcerpt {
5868            diff_transforms: cursor.diff_transforms,
5869            excerpt: start_excerpt,
5870            offset,
5871            buffer_offset,
5872            excerpt_offset,
5873        })
5874    }
5875
5876    pub fn selections_in_range<'a>(
5877        &'a self,
5878        range: &'a Range<Anchor>,
5879        include_local: bool,
5880    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
5881        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
5882        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
5883        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
5884        cursor.seek(start_locator, Bias::Left, &());
5885        cursor
5886            .take_while(move |excerpt| excerpt.locator <= *end_locator)
5887            .flat_map(move |excerpt| {
5888                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
5889                if excerpt.id == range.start.excerpt_id {
5890                    query_range.start = range.start.text_anchor;
5891                }
5892                if excerpt.id == range.end.excerpt_id {
5893                    query_range.end = range.end.text_anchor;
5894                }
5895
5896                excerpt
5897                    .buffer
5898                    .selections_in_range(query_range, include_local)
5899                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
5900                        selections.map(move |selection| {
5901                            let mut start = Anchor {
5902                                buffer_id: Some(excerpt.buffer_id),
5903                                excerpt_id: excerpt.id,
5904                                text_anchor: selection.start,
5905                                diff_base_anchor: None,
5906                            };
5907                            let mut end = Anchor {
5908                                buffer_id: Some(excerpt.buffer_id),
5909                                excerpt_id: excerpt.id,
5910                                text_anchor: selection.end,
5911                                diff_base_anchor: None,
5912                            };
5913                            if range.start.cmp(&start, self).is_gt() {
5914                                start = range.start;
5915                            }
5916                            if range.end.cmp(&end, self).is_lt() {
5917                                end = range.end;
5918                            }
5919
5920                            (
5921                                replica_id,
5922                                line_mode,
5923                                cursor_shape,
5924                                Selection {
5925                                    id: selection.id,
5926                                    start,
5927                                    end,
5928                                    reversed: selection.reversed,
5929                                    goal: selection.goal,
5930                                },
5931                            )
5932                        })
5933                    })
5934            })
5935    }
5936
5937    pub fn show_headers(&self) -> bool {
5938        self.show_headers
5939    }
5940
5941    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
5942        self.diffs.get(&buffer_id)
5943    }
5944}
5945
5946#[cfg(any(test, feature = "test-support"))]
5947impl MultiBufferSnapshot {
5948    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
5949        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
5950        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
5951        start..end
5952    }
5953
5954    #[cfg(any(test, feature = "test-support"))]
5955    fn check_invariants(&self) {
5956        let excerpts = self.excerpts.items(&());
5957        let excerpt_ids = self.excerpt_ids.items(&());
5958
5959        for (ix, excerpt) in excerpts.iter().enumerate() {
5960            if ix == 0 {
5961                if excerpt.locator <= Locator::min() {
5962                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
5963                }
5964            } else if excerpt.locator <= excerpts[ix - 1].locator {
5965                panic!("excerpts are out-of-order: {:?}", excerpts);
5966            }
5967        }
5968
5969        for (ix, entry) in excerpt_ids.iter().enumerate() {
5970            if ix == 0 {
5971                if entry.id.cmp(&ExcerptId::min(), &self).is_le() {
5972                    panic!("invalid first excerpt id {:?}", entry.id);
5973                }
5974            } else if entry.id <= excerpt_ids[ix - 1].id {
5975                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
5976            }
5977        }
5978
5979        if self.diff_transforms.summary().input != self.excerpts.summary().text {
5980            panic!(
5981                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
5982                self.excerpts.summary().text.len,
5983                self.diff_transforms.summary().input,
5984                self.diff_transforms.items(&()),
5985            );
5986        }
5987
5988        let mut prev_transform: Option<&DiffTransform> = None;
5989        for item in self.diff_transforms.iter() {
5990            if let DiffTransform::BufferContent {
5991                summary,
5992                inserted_hunk_info,
5993            } = item
5994            {
5995                if let Some(DiffTransform::BufferContent {
5996                    inserted_hunk_info: prev_inserted_hunk_info,
5997                    ..
5998                }) = prev_transform
5999                {
6000                    if *inserted_hunk_info == *prev_inserted_hunk_info {
6001                        panic!(
6002                            "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
6003                            self.diff_transforms.items(&()));
6004                    }
6005                }
6006                if summary.len == 0 && !self.is_empty() {
6007                    panic!("empty buffer content transform");
6008                }
6009            }
6010            prev_transform = Some(item);
6011        }
6012    }
6013}
6014
6015impl<'a, D> MultiBufferCursor<'a, D>
6016where
6017    D: TextDimension + Ord + Sub<D, Output = D>,
6018{
6019    fn seek(&mut self, position: &D) {
6020        self.cached_region.take();
6021        self.diff_transforms
6022            .seek(&OutputDimension(*position), Bias::Right, &());
6023        if self.diff_transforms.item().is_none() && *position == self.diff_transforms.start().0 .0 {
6024            self.diff_transforms.prev(&());
6025        }
6026
6027        let mut excerpt_position = self.diff_transforms.start().1 .0;
6028        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6029            let overshoot = *position - self.diff_transforms.start().0 .0;
6030            excerpt_position.add_assign(&overshoot);
6031        }
6032
6033        self.excerpts
6034            .seek(&ExcerptDimension(excerpt_position), Bias::Right, &());
6035        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6036            self.excerpts.prev(&());
6037        }
6038    }
6039
6040    fn seek_forward(&mut self, position: &D) {
6041        self.cached_region.take();
6042        self.diff_transforms
6043            .seek_forward(&OutputDimension(*position), Bias::Right, &());
6044        if self.diff_transforms.item().is_none() && *position == self.diff_transforms.start().0 .0 {
6045            self.diff_transforms.prev(&());
6046        }
6047
6048        let overshoot = *position - self.diff_transforms.start().0 .0;
6049        let mut excerpt_position = self.diff_transforms.start().1 .0;
6050        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6051            excerpt_position.add_assign(&overshoot);
6052        }
6053
6054        self.excerpts
6055            .seek_forward(&ExcerptDimension(excerpt_position), Bias::Right, &());
6056        if self.excerpts.item().is_none() && excerpt_position == self.excerpts.start().0 {
6057            self.excerpts.prev(&());
6058        }
6059    }
6060
6061    fn next_excerpt(&mut self) {
6062        self.excerpts.next(&());
6063        self.seek_to_start_of_current_excerpt();
6064    }
6065
6066    fn prev_excerpt(&mut self) {
6067        self.excerpts.prev(&());
6068        self.seek_to_start_of_current_excerpt();
6069    }
6070
6071    fn seek_to_start_of_current_excerpt(&mut self) {
6072        self.cached_region.take();
6073        self.diff_transforms
6074            .seek(self.excerpts.start(), Bias::Left, &());
6075        if self.diff_transforms.end(&()).1 == *self.excerpts.start()
6076            && self.diff_transforms.start().1 < *self.excerpts.start()
6077            && self.diff_transforms.next_item().is_some()
6078        {
6079            self.diff_transforms.next(&());
6080        }
6081    }
6082
6083    fn next(&mut self) {
6084        self.cached_region.take();
6085        match self.diff_transforms.end(&()).1.cmp(&self.excerpts.end(&())) {
6086            cmp::Ordering::Less => self.diff_transforms.next(&()),
6087            cmp::Ordering::Greater => self.excerpts.next(&()),
6088            cmp::Ordering::Equal => {
6089                self.diff_transforms.next(&());
6090                if self.diff_transforms.end(&()).1 > self.excerpts.end(&())
6091                    || self.diff_transforms.item().is_none()
6092                {
6093                    self.excerpts.next(&());
6094                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
6095                    self.diff_transforms.item()
6096                {
6097                    if self
6098                        .excerpts
6099                        .item()
6100                        .map_or(false, |excerpt| excerpt.id != hunk_info.excerpt_id)
6101                    {
6102                        self.excerpts.next(&());
6103                    }
6104                }
6105            }
6106        }
6107    }
6108
6109    fn prev(&mut self) {
6110        self.cached_region.take();
6111        match self.diff_transforms.start().1.cmp(self.excerpts.start()) {
6112            cmp::Ordering::Less => self.excerpts.prev(&()),
6113            cmp::Ordering::Greater => self.diff_transforms.prev(&()),
6114            cmp::Ordering::Equal => {
6115                self.diff_transforms.prev(&());
6116                if self.diff_transforms.start().1 < *self.excerpts.start()
6117                    || self.diff_transforms.item().is_none()
6118                {
6119                    self.excerpts.prev(&());
6120                }
6121            }
6122        }
6123    }
6124
6125    fn region(&mut self) -> Option<MultiBufferRegion<'a, D>> {
6126        if self.cached_region.is_none() {
6127            self.cached_region = self.build_region();
6128        }
6129        self.cached_region.clone()
6130    }
6131
6132    fn is_at_end_of_excerpt(&mut self) -> bool {
6133        if self.diff_transforms.end(&()).1 < self.excerpts.end(&()) {
6134            return false;
6135        } else if self.diff_transforms.end(&()).1 > self.excerpts.end(&())
6136            || self.diff_transforms.item().is_none()
6137        {
6138            return true;
6139        }
6140
6141        let next_transform = self.diff_transforms.next_item();
6142        next_transform.map_or(true, |next_transform| match next_transform {
6143            DiffTransform::BufferContent { .. } => true,
6144            DiffTransform::DeletedHunk { hunk_info, .. } => self
6145                .excerpts
6146                .item()
6147                .map_or(false, |excerpt| excerpt.id != hunk_info.excerpt_id),
6148        })
6149    }
6150
6151    fn main_buffer_position(&self) -> Option<D> {
6152        let excerpt = self.excerpts.item()?;
6153        let buffer = &excerpt.buffer;
6154        let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6155        let mut buffer_start = buffer_context_start;
6156        let overshoot = self.diff_transforms.end(&()).1 .0 - self.excerpts.start().0;
6157        buffer_start.add_assign(&overshoot);
6158        Some(buffer_start)
6159    }
6160
6161    fn build_region(&self) -> Option<MultiBufferRegion<'a, D>> {
6162        let excerpt = self.excerpts.item()?;
6163        match self.diff_transforms.item()? {
6164            DiffTransform::DeletedHunk {
6165                buffer_id,
6166                base_text_byte_range,
6167                has_trailing_newline,
6168                hunk_info,
6169                ..
6170            } => {
6171                let diff = self.diffs.get(&buffer_id)?;
6172                let buffer = diff.base_text();
6173                let mut rope_cursor = buffer.as_rope().cursor(0);
6174                let buffer_start = rope_cursor.summary::<D>(base_text_byte_range.start);
6175                let buffer_range_len = rope_cursor.summary::<D>(base_text_byte_range.end);
6176                let mut buffer_end = buffer_start;
6177                buffer_end.add_assign(&buffer_range_len);
6178                let start = self.diff_transforms.start().0 .0;
6179                let end = self.diff_transforms.end(&()).0 .0;
6180                return Some(MultiBufferRegion {
6181                    buffer,
6182                    excerpt,
6183                    has_trailing_newline: *has_trailing_newline,
6184                    is_main_buffer: false,
6185                    diff_hunk_status: Some(DiffHunkStatus::deleted(
6186                        hunk_info.hunk_secondary_status,
6187                    )),
6188                    buffer_range: buffer_start..buffer_end,
6189                    range: start..end,
6190                });
6191            }
6192            DiffTransform::BufferContent {
6193                inserted_hunk_info, ..
6194            } => {
6195                let buffer = &excerpt.buffer;
6196                let buffer_context_start = excerpt.range.context.start.summary::<D>(buffer);
6197
6198                let mut start = self.diff_transforms.start().0 .0;
6199                let mut buffer_start = buffer_context_start;
6200                if self.diff_transforms.start().1 < *self.excerpts.start() {
6201                    let overshoot = self.excerpts.start().0 - self.diff_transforms.start().1 .0;
6202                    start.add_assign(&overshoot);
6203                } else {
6204                    let overshoot = self.diff_transforms.start().1 .0 - self.excerpts.start().0;
6205                    buffer_start.add_assign(&overshoot);
6206                }
6207
6208                let mut end;
6209                let mut buffer_end;
6210                let has_trailing_newline;
6211                if self.diff_transforms.end(&()).1 .0 < self.excerpts.end(&()).0 {
6212                    let overshoot = self.diff_transforms.end(&()).1 .0 - self.excerpts.start().0;
6213                    end = self.diff_transforms.end(&()).0 .0;
6214                    buffer_end = buffer_context_start;
6215                    buffer_end.add_assign(&overshoot);
6216                    has_trailing_newline = false;
6217                } else {
6218                    let overshoot = self.excerpts.end(&()).0 - self.diff_transforms.start().1 .0;
6219                    end = self.diff_transforms.start().0 .0;
6220                    end.add_assign(&overshoot);
6221                    buffer_end = excerpt.range.context.end.summary::<D>(buffer);
6222                    has_trailing_newline = excerpt.has_trailing_newline;
6223                };
6224
6225                Some(MultiBufferRegion {
6226                    buffer,
6227                    excerpt,
6228                    has_trailing_newline,
6229                    is_main_buffer: true,
6230                    diff_hunk_status: inserted_hunk_info
6231                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
6232                    buffer_range: buffer_start..buffer_end,
6233                    range: start..end,
6234                })
6235            }
6236        }
6237    }
6238
6239    fn excerpt(&self) -> Option<&'a Excerpt> {
6240        self.excerpts.item()
6241    }
6242}
6243
6244impl History {
6245    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
6246        self.transaction_depth += 1;
6247        if self.transaction_depth == 1 {
6248            let id = self.next_transaction_id.tick();
6249            self.undo_stack.push(Transaction {
6250                id,
6251                buffer_transactions: Default::default(),
6252                first_edit_at: now,
6253                last_edit_at: now,
6254                suppress_grouping: false,
6255            });
6256            Some(id)
6257        } else {
6258            None
6259        }
6260    }
6261
6262    fn end_transaction(
6263        &mut self,
6264        now: Instant,
6265        buffer_transactions: HashMap<BufferId, TransactionId>,
6266    ) -> bool {
6267        assert_ne!(self.transaction_depth, 0);
6268        self.transaction_depth -= 1;
6269        if self.transaction_depth == 0 {
6270            if buffer_transactions.is_empty() {
6271                self.undo_stack.pop();
6272                false
6273            } else {
6274                self.redo_stack.clear();
6275                let transaction = self.undo_stack.last_mut().unwrap();
6276                transaction.last_edit_at = now;
6277                for (buffer_id, transaction_id) in buffer_transactions {
6278                    transaction
6279                        .buffer_transactions
6280                        .entry(buffer_id)
6281                        .or_insert(transaction_id);
6282                }
6283                true
6284            }
6285        } else {
6286            false
6287        }
6288    }
6289
6290    fn push_transaction<'a, T>(
6291        &mut self,
6292        buffer_transactions: T,
6293        now: Instant,
6294        cx: &Context<MultiBuffer>,
6295    ) where
6296        T: IntoIterator<Item = (&'a Entity<Buffer>, &'a language::Transaction)>,
6297    {
6298        assert_eq!(self.transaction_depth, 0);
6299        let transaction = Transaction {
6300            id: self.next_transaction_id.tick(),
6301            buffer_transactions: buffer_transactions
6302                .into_iter()
6303                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
6304                .collect(),
6305            first_edit_at: now,
6306            last_edit_at: now,
6307            suppress_grouping: false,
6308        };
6309        if !transaction.buffer_transactions.is_empty() {
6310            self.undo_stack.push(transaction);
6311            self.redo_stack.clear();
6312        }
6313    }
6314
6315    fn finalize_last_transaction(&mut self) {
6316        if let Some(transaction) = self.undo_stack.last_mut() {
6317            transaction.suppress_grouping = true;
6318        }
6319    }
6320
6321    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
6322        if let Some(ix) = self
6323            .undo_stack
6324            .iter()
6325            .rposition(|transaction| transaction.id == transaction_id)
6326        {
6327            Some(self.undo_stack.remove(ix))
6328        } else if let Some(ix) = self
6329            .redo_stack
6330            .iter()
6331            .rposition(|transaction| transaction.id == transaction_id)
6332        {
6333            Some(self.redo_stack.remove(ix))
6334        } else {
6335            None
6336        }
6337    }
6338
6339    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
6340        self.undo_stack
6341            .iter()
6342            .find(|transaction| transaction.id == transaction_id)
6343            .or_else(|| {
6344                self.redo_stack
6345                    .iter()
6346                    .find(|transaction| transaction.id == transaction_id)
6347            })
6348    }
6349
6350    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
6351        self.undo_stack
6352            .iter_mut()
6353            .find(|transaction| transaction.id == transaction_id)
6354            .or_else(|| {
6355                self.redo_stack
6356                    .iter_mut()
6357                    .find(|transaction| transaction.id == transaction_id)
6358            })
6359    }
6360
6361    fn pop_undo(&mut self) -> Option<&mut Transaction> {
6362        assert_eq!(self.transaction_depth, 0);
6363        if let Some(transaction) = self.undo_stack.pop() {
6364            self.redo_stack.push(transaction);
6365            self.redo_stack.last_mut()
6366        } else {
6367            None
6368        }
6369    }
6370
6371    fn pop_redo(&mut self) -> Option<&mut Transaction> {
6372        assert_eq!(self.transaction_depth, 0);
6373        if let Some(transaction) = self.redo_stack.pop() {
6374            self.undo_stack.push(transaction);
6375            self.undo_stack.last_mut()
6376        } else {
6377            None
6378        }
6379    }
6380
6381    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
6382        let ix = self
6383            .undo_stack
6384            .iter()
6385            .rposition(|transaction| transaction.id == transaction_id)?;
6386        let transaction = self.undo_stack.remove(ix);
6387        self.redo_stack.push(transaction);
6388        self.redo_stack.last()
6389    }
6390
6391    fn group(&mut self) -> Option<TransactionId> {
6392        let mut count = 0;
6393        let mut transactions = self.undo_stack.iter();
6394        if let Some(mut transaction) = transactions.next_back() {
6395            while let Some(prev_transaction) = transactions.next_back() {
6396                if !prev_transaction.suppress_grouping
6397                    && transaction.first_edit_at - prev_transaction.last_edit_at
6398                        <= self.group_interval
6399                {
6400                    transaction = prev_transaction;
6401                    count += 1;
6402                } else {
6403                    break;
6404                }
6405            }
6406        }
6407        self.group_trailing(count)
6408    }
6409
6410    fn group_until(&mut self, transaction_id: TransactionId) {
6411        let mut count = 0;
6412        for transaction in self.undo_stack.iter().rev() {
6413            if transaction.id == transaction_id {
6414                self.group_trailing(count);
6415                break;
6416            } else if transaction.suppress_grouping {
6417                break;
6418            } else {
6419                count += 1;
6420            }
6421        }
6422    }
6423
6424    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
6425        let new_len = self.undo_stack.len() - n;
6426        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
6427        if let Some(last_transaction) = transactions_to_keep.last_mut() {
6428            if let Some(transaction) = transactions_to_merge.last() {
6429                last_transaction.last_edit_at = transaction.last_edit_at;
6430            }
6431            for to_merge in transactions_to_merge {
6432                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
6433                    last_transaction
6434                        .buffer_transactions
6435                        .entry(*buffer_id)
6436                        .or_insert(*transaction_id);
6437                }
6438            }
6439        }
6440
6441        self.undo_stack.truncate(new_len);
6442        self.undo_stack.last().map(|t| t.id)
6443    }
6444}
6445
6446impl Excerpt {
6447    fn new(
6448        id: ExcerptId,
6449        locator: Locator,
6450        buffer_id: BufferId,
6451        buffer: BufferSnapshot,
6452        range: ExcerptRange<text::Anchor>,
6453        has_trailing_newline: bool,
6454    ) -> Self {
6455        Excerpt {
6456            id,
6457            locator,
6458            max_buffer_row: range.context.end.to_point(&buffer).row,
6459            text_summary: buffer
6460                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
6461            buffer_id,
6462            buffer,
6463            range,
6464            has_trailing_newline,
6465        }
6466    }
6467
6468    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
6469        let content_start = self.range.context.start.to_offset(&self.buffer);
6470        let chunks_start = content_start + range.start;
6471        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6472
6473        let footer_height = if self.has_trailing_newline
6474            && range.start <= self.text_summary.len
6475            && range.end > self.text_summary.len
6476        {
6477            1
6478        } else {
6479            0
6480        };
6481
6482        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
6483
6484        ExcerptChunks {
6485            excerpt_id: self.id,
6486            content_chunks,
6487            footer_height,
6488        }
6489    }
6490
6491    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
6492        let content_start = self.range.context.start.to_offset(&self.buffer);
6493        let chunks_start = content_start + range.start;
6494        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
6495        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
6496        excerpt_chunks.footer_height = if self.has_trailing_newline
6497            && range.start <= self.text_summary.len
6498            && range.end > self.text_summary.len
6499        {
6500            1
6501        } else {
6502            0
6503        };
6504    }
6505
6506    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
6507        if text_anchor
6508            .cmp(&self.range.context.start, &self.buffer)
6509            .is_lt()
6510        {
6511            self.range.context.start
6512        } else if text_anchor
6513            .cmp(&self.range.context.end, &self.buffer)
6514            .is_gt()
6515        {
6516            self.range.context.end
6517        } else {
6518            text_anchor
6519        }
6520    }
6521
6522    fn contains(&self, anchor: &Anchor) -> bool {
6523        Some(self.buffer_id) == anchor.buffer_id
6524            && self
6525                .range
6526                .context
6527                .start
6528                .cmp(&anchor.text_anchor, &self.buffer)
6529                .is_le()
6530            && self
6531                .range
6532                .context
6533                .end
6534                .cmp(&anchor.text_anchor, &self.buffer)
6535                .is_ge()
6536    }
6537
6538    /// The [`Excerpt`]'s start offset in its [`Buffer`]
6539    fn buffer_start_offset(&self) -> usize {
6540        self.range.context.start.to_offset(&self.buffer)
6541    }
6542
6543    /// The [`Excerpt`]'s end offset in its [`Buffer`]
6544    fn buffer_end_offset(&self) -> usize {
6545        self.buffer_start_offset() + self.text_summary.len
6546    }
6547}
6548
6549impl<'a> MultiBufferExcerpt<'a> {
6550    pub fn id(&self) -> ExcerptId {
6551        self.excerpt.id
6552    }
6553
6554    pub fn buffer_id(&self) -> BufferId {
6555        self.excerpt.buffer_id
6556    }
6557
6558    pub fn start_anchor(&self) -> Anchor {
6559        Anchor {
6560            buffer_id: Some(self.excerpt.buffer_id),
6561            excerpt_id: self.excerpt.id,
6562            text_anchor: self.excerpt.range.context.start,
6563            diff_base_anchor: None,
6564        }
6565    }
6566
6567    pub fn end_anchor(&self) -> Anchor {
6568        Anchor {
6569            buffer_id: Some(self.excerpt.buffer_id),
6570            excerpt_id: self.excerpt.id,
6571            text_anchor: self.excerpt.range.context.end,
6572            diff_base_anchor: None,
6573        }
6574    }
6575
6576    pub fn buffer(&self) -> &'a BufferSnapshot {
6577        &self.excerpt.buffer
6578    }
6579
6580    pub fn buffer_range(&self) -> Range<usize> {
6581        self.buffer_offset
6582            ..self
6583                .excerpt
6584                .range
6585                .context
6586                .end
6587                .to_offset(&self.excerpt.buffer.text)
6588    }
6589
6590    pub fn start_offset(&self) -> usize {
6591        self.offset
6592    }
6593
6594    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
6595    pub fn map_offset_to_buffer(&mut self, offset: usize) -> usize {
6596        self.map_range_to_buffer(offset..offset).start
6597    }
6598
6599    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
6600    pub fn map_range_to_buffer(&mut self, range: Range<usize>) -> Range<usize> {
6601        self.diff_transforms
6602            .seek(&OutputDimension(range.start), Bias::Right, &());
6603        let start = self.map_offset_to_buffer_internal(range.start);
6604        let end = if range.end > range.start {
6605            self.diff_transforms
6606                .seek_forward(&OutputDimension(range.end), Bias::Right, &());
6607            self.map_offset_to_buffer_internal(range.end)
6608        } else {
6609            start
6610        };
6611        start..end
6612    }
6613
6614    fn map_offset_to_buffer_internal(&self, offset: usize) -> usize {
6615        let mut excerpt_offset = self.diff_transforms.start().1.clone();
6616        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
6617            excerpt_offset.0 += offset - self.diff_transforms.start().0 .0;
6618        };
6619        let offset_in_excerpt = excerpt_offset.0.saturating_sub(self.excerpt_offset.0);
6620        self.buffer_offset + offset_in_excerpt
6621    }
6622
6623    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
6624    pub fn map_offset_from_buffer(&mut self, buffer_offset: usize) -> usize {
6625        self.map_range_from_buffer(buffer_offset..buffer_offset)
6626            .start
6627    }
6628
6629    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
6630    pub fn map_range_from_buffer(&mut self, buffer_range: Range<usize>) -> Range<usize> {
6631        if buffer_range.start < self.buffer_offset {
6632            log::warn!("Attempting to map a range from a buffer offset that starts before the current buffer offset");
6633            return buffer_range;
6634        }
6635        let overshoot = buffer_range.start - self.buffer_offset;
6636        let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
6637        self.diff_transforms.seek(&excerpt_offset, Bias::Right, &());
6638        if excerpt_offset.0 < self.diff_transforms.start().1 .0 {
6639            log::warn!("Attempting to map a range from a buffer offset that starts before the current buffer offset");
6640            return buffer_range;
6641        }
6642        let overshoot = excerpt_offset.0 - self.diff_transforms.start().1 .0;
6643        let start = self.diff_transforms.start().0 .0 + overshoot;
6644
6645        let end = if buffer_range.end > buffer_range.start {
6646            let overshoot = buffer_range.end - self.buffer_offset;
6647            let excerpt_offset = ExcerptDimension(self.excerpt_offset.0 + overshoot);
6648            self.diff_transforms
6649                .seek_forward(&excerpt_offset, Bias::Right, &());
6650            let overshoot = excerpt_offset.0 - self.diff_transforms.start().1 .0;
6651            self.diff_transforms.start().0 .0 + overshoot
6652        } else {
6653            start
6654        };
6655
6656        start..end
6657    }
6658
6659    /// Returns true if the entirety of the given range is in the buffer's excerpt
6660    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
6661        range.start >= self.excerpt.buffer_start_offset()
6662            && range.end <= self.excerpt.buffer_end_offset()
6663    }
6664
6665    pub fn max_buffer_row(&self) -> u32 {
6666        self.excerpt.max_buffer_row
6667    }
6668}
6669
6670impl ExcerptId {
6671    pub fn min() -> Self {
6672        Self(0)
6673    }
6674
6675    pub fn max() -> Self {
6676        Self(usize::MAX)
6677    }
6678
6679    pub fn to_proto(&self) -> u64 {
6680        self.0 as _
6681    }
6682
6683    pub fn from_proto(proto: u64) -> Self {
6684        Self(proto as _)
6685    }
6686
6687    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
6688        let a = snapshot.excerpt_locator_for_id(*self);
6689        let b = snapshot.excerpt_locator_for_id(*other);
6690        a.cmp(b).then_with(|| self.0.cmp(&other.0))
6691    }
6692}
6693
6694impl From<ExcerptId> for usize {
6695    fn from(val: ExcerptId) -> Self {
6696        val.0
6697    }
6698}
6699
6700impl fmt::Debug for Excerpt {
6701    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
6702        f.debug_struct("Excerpt")
6703            .field("id", &self.id)
6704            .field("locator", &self.locator)
6705            .field("buffer_id", &self.buffer_id)
6706            .field("range", &self.range)
6707            .field("text_summary", &self.text_summary)
6708            .field("has_trailing_newline", &self.has_trailing_newline)
6709            .finish()
6710    }
6711}
6712
6713impl sum_tree::Item for Excerpt {
6714    type Summary = ExcerptSummary;
6715
6716    fn summary(&self, _cx: &()) -> Self::Summary {
6717        let mut text = self.text_summary;
6718        if self.has_trailing_newline {
6719            text += TextSummary::from("\n");
6720        }
6721        ExcerptSummary {
6722            excerpt_id: self.id,
6723            excerpt_locator: self.locator.clone(),
6724            widest_line_number: self.max_buffer_row,
6725            text,
6726        }
6727    }
6728}
6729
6730impl sum_tree::Item for ExcerptIdMapping {
6731    type Summary = ExcerptId;
6732
6733    fn summary(&self, _cx: &()) -> Self::Summary {
6734        self.id
6735    }
6736}
6737
6738impl sum_tree::KeyedItem for ExcerptIdMapping {
6739    type Key = ExcerptId;
6740
6741    fn key(&self) -> Self::Key {
6742        self.id
6743    }
6744}
6745
6746impl DiffTransform {
6747    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
6748        match self {
6749            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
6750            DiffTransform::BufferContent {
6751                inserted_hunk_info, ..
6752            } => *inserted_hunk_info,
6753        }
6754    }
6755}
6756
6757impl sum_tree::Item for DiffTransform {
6758    type Summary = DiffTransformSummary;
6759
6760    fn summary(&self, _: &<Self::Summary as sum_tree::Summary>::Context) -> Self::Summary {
6761        match self {
6762            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
6763                input: *summary,
6764                output: *summary,
6765            },
6766            DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
6767                input: TextSummary::default(),
6768                output: *summary,
6769            },
6770        }
6771    }
6772}
6773
6774impl DiffTransformSummary {
6775    fn excerpt_len(&self) -> ExcerptOffset {
6776        ExcerptOffset::new(self.input.len)
6777    }
6778}
6779
6780impl sum_tree::Summary for DiffTransformSummary {
6781    type Context = ();
6782
6783    fn zero(_: &Self::Context) -> Self {
6784        DiffTransformSummary {
6785            input: TextSummary::default(),
6786            output: TextSummary::default(),
6787        }
6788    }
6789
6790    fn add_summary(&mut self, summary: &Self, _: &Self::Context) {
6791        self.input += &summary.input;
6792        self.output += &summary.output;
6793    }
6794}
6795
6796impl sum_tree::Summary for ExcerptId {
6797    type Context = ();
6798
6799    fn zero(_cx: &()) -> Self {
6800        Default::default()
6801    }
6802
6803    fn add_summary(&mut self, other: &Self, _: &()) {
6804        *self = *other;
6805    }
6806}
6807
6808impl sum_tree::Summary for ExcerptSummary {
6809    type Context = ();
6810
6811    fn zero(_cx: &()) -> Self {
6812        Default::default()
6813    }
6814
6815    fn add_summary(&mut self, summary: &Self, _: &()) {
6816        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
6817        self.excerpt_locator = summary.excerpt_locator.clone();
6818        self.text.add_summary(&summary.text, &());
6819        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
6820    }
6821}
6822
6823impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptOffset {
6824    fn zero(_cx: &()) -> Self {
6825        Default::default()
6826    }
6827
6828    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
6829        self.value += summary.text.len;
6830    }
6831}
6832
6833impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for ExcerptOffset {
6834    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
6835        Ord::cmp(&self.value, &cursor_location.text.len)
6836    }
6837}
6838
6839impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
6840    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
6841        Ord::cmp(&Some(self), cursor_location)
6842    }
6843}
6844
6845impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
6846    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
6847        Ord::cmp(self, &cursor_location.excerpt_locator)
6848    }
6849}
6850
6851impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptPoint {
6852    fn zero(_cx: &()) -> Self {
6853        Default::default()
6854    }
6855
6856    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
6857        self.value += summary.text.lines;
6858    }
6859}
6860
6861impl<'a, D: TextDimension + Default> sum_tree::Dimension<'a, ExcerptSummary>
6862    for ExcerptDimension<D>
6863{
6864    fn zero(_: &()) -> Self {
6865        ExcerptDimension(D::default())
6866    }
6867
6868    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
6869        self.0.add_assign(&D::from_text_summary(&summary.text))
6870    }
6871}
6872
6873impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
6874    fn zero(_cx: &()) -> Self {
6875        Default::default()
6876    }
6877
6878    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
6879        *self = Some(&summary.excerpt_locator);
6880    }
6881}
6882
6883impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
6884    fn zero(_cx: &()) -> Self {
6885        Default::default()
6886    }
6887
6888    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
6889        *self = Some(summary.excerpt_id);
6890    }
6891}
6892
6893#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
6894struct ExcerptDimension<T>(T);
6895
6896#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
6897struct OutputDimension<T>(T);
6898
6899impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptOffset {
6900    fn zero(_: &()) -> Self {
6901        ExcerptOffset::new(0)
6902    }
6903
6904    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6905        self.value += summary.input.len;
6906    }
6907}
6908
6909impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptPoint {
6910    fn zero(_: &()) -> Self {
6911        ExcerptPoint::new(0, 0)
6912    }
6913
6914    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6915        self.value += summary.input.lines;
6916    }
6917}
6918
6919impl<D: TextDimension + Ord> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
6920    for ExcerptDimension<D>
6921{
6922    fn cmp(&self, cursor_location: &DiffTransformSummary, _: &()) -> cmp::Ordering {
6923        Ord::cmp(&self.0, &D::from_text_summary(&cursor_location.input))
6924    }
6925}
6926
6927impl<D: TextDimension + Ord>
6928    sum_tree::SeekTarget<'_, DiffTransformSummary, (OutputDimension<D>, ExcerptDimension<D>)>
6929    for ExcerptDimension<D>
6930{
6931    fn cmp(
6932        &self,
6933        cursor_location: &(OutputDimension<D>, ExcerptDimension<D>),
6934        _: &(),
6935    ) -> cmp::Ordering {
6936        Ord::cmp(&self.0, &cursor_location.1 .0)
6937    }
6938}
6939
6940impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for ExcerptDimension<D> {
6941    fn zero(_: &()) -> Self {
6942        ExcerptDimension(D::default())
6943    }
6944
6945    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6946        self.0.add_assign(&D::from_text_summary(&summary.input))
6947    }
6948}
6949
6950impl<'a, D: TextDimension> sum_tree::Dimension<'a, DiffTransformSummary> for OutputDimension<D> {
6951    fn zero(_: &()) -> Self {
6952        OutputDimension(D::default())
6953    }
6954
6955    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6956        self.0.add_assign(&D::from_text_summary(&summary.output))
6957    }
6958}
6959
6960impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for TextSummary {
6961    fn zero(_: &()) -> Self {
6962        TextSummary::default()
6963    }
6964
6965    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6966        *self += summary.output
6967    }
6968}
6969
6970impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for usize {
6971    fn zero(_: &()) -> Self {
6972        0
6973    }
6974
6975    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6976        *self += summary.output.len
6977    }
6978}
6979
6980impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for Point {
6981    fn zero(_: &()) -> Self {
6982        Point::new(0, 0)
6983    }
6984
6985    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: &()) {
6986        *self += summary.output.lines
6987    }
6988}
6989
6990impl MultiBufferRows<'_> {
6991    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
6992        self.point = Point::new(row, 0);
6993        self.cursor.seek(&self.point);
6994    }
6995}
6996
6997impl Iterator for MultiBufferRows<'_> {
6998    type Item = RowInfo;
6999
7000    fn next(&mut self) -> Option<Self::Item> {
7001        if self.is_empty && self.point.row == 0 {
7002            self.point += Point::new(1, 0);
7003            return Some(RowInfo {
7004                buffer_id: None,
7005                buffer_row: Some(0),
7006                multibuffer_row: Some(MultiBufferRow(0)),
7007                diff_status: None,
7008            });
7009        }
7010
7011        let mut region = self.cursor.region()?;
7012        while self.point >= region.range.end {
7013            self.cursor.next();
7014            if let Some(next_region) = self.cursor.region() {
7015                region = next_region;
7016            } else {
7017                if self.point == self.cursor.diff_transforms.end(&()).0 .0 {
7018                    let multibuffer_row = MultiBufferRow(self.point.row);
7019                    self.point += Point::new(1, 0);
7020                    let last_excerpt = self
7021                        .cursor
7022                        .excerpts
7023                        .item()
7024                        .or(self.cursor.excerpts.prev_item())?;
7025                    let last_row = last_excerpt
7026                        .range
7027                        .context
7028                        .end
7029                        .to_point(&last_excerpt.buffer)
7030                        .row;
7031                    return Some(RowInfo {
7032                        buffer_id: Some(last_excerpt.buffer_id),
7033                        buffer_row: Some(last_row),
7034                        multibuffer_row: Some(multibuffer_row),
7035                        diff_status: None,
7036                    });
7037                } else {
7038                    return None;
7039                }
7040            };
7041        }
7042
7043        let overshoot = self.point - region.range.start;
7044        let buffer_point = region.buffer_range.start + overshoot;
7045        let result = Some(RowInfo {
7046            buffer_id: Some(region.buffer.remote_id()),
7047            buffer_row: Some(buffer_point.row),
7048            multibuffer_row: Some(MultiBufferRow(self.point.row)),
7049            diff_status: region
7050                .diff_hunk_status
7051                .filter(|_| self.point < region.range.end),
7052        });
7053        self.point += Point::new(1, 0);
7054        result
7055    }
7056}
7057
7058impl<'a> MultiBufferChunks<'a> {
7059    pub fn offset(&self) -> usize {
7060        self.range.start
7061    }
7062
7063    pub fn seek(&mut self, range: Range<usize>) {
7064        self.diff_transforms.seek(&range.end, Bias::Right, &());
7065        let mut excerpt_end = self.diff_transforms.start().1;
7066        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7067            let overshoot = range.end - self.diff_transforms.start().0;
7068            excerpt_end.value += overshoot;
7069        }
7070
7071        self.diff_transforms.seek(&range.start, Bias::Right, &());
7072        let mut excerpt_start = self.diff_transforms.start().1;
7073        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7074            let overshoot = range.start - self.diff_transforms.start().0;
7075            excerpt_start.value += overshoot;
7076        }
7077
7078        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
7079        self.buffer_chunk.take();
7080        self.range = range;
7081    }
7082
7083    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
7084        self.excerpt_offset_range = new_range.clone();
7085        self.excerpts.seek(&new_range.start, Bias::Right, &());
7086        if let Some(excerpt) = self.excerpts.item() {
7087            let excerpt_start = *self.excerpts.start();
7088            if let Some(excerpt_chunks) = self
7089                .excerpt_chunks
7090                .as_mut()
7091                .filter(|chunks| excerpt.id == chunks.excerpt_id)
7092            {
7093                excerpt.seek_chunks(
7094                    excerpt_chunks,
7095                    (self.excerpt_offset_range.start - excerpt_start).value
7096                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7097                );
7098            } else {
7099                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7100                    (self.excerpt_offset_range.start - excerpt_start).value
7101                        ..(self.excerpt_offset_range.end - excerpt_start).value,
7102                    self.language_aware,
7103                ));
7104            }
7105        } else {
7106            self.excerpt_chunks = None;
7107        }
7108    }
7109
7110    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
7111        loop {
7112            if self.excerpt_offset_range.is_empty() {
7113                return None;
7114            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
7115                self.excerpt_offset_range.start.value += chunk.text.len();
7116                return Some(chunk);
7117            } else {
7118                self.excerpts.next(&());
7119                let excerpt = self.excerpts.item()?;
7120                self.excerpt_chunks = Some(excerpt.chunks_in_range(
7121                    0..(self.excerpt_offset_range.end - *self.excerpts.start()).value,
7122                    self.language_aware,
7123                ));
7124            }
7125        }
7126    }
7127}
7128
7129impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
7130    type Item = &'a str;
7131
7132    fn next(&mut self) -> Option<Self::Item> {
7133        let mut region = self.cursor.region()?;
7134        if self.offset == region.range.start {
7135            self.cursor.prev();
7136            region = self.cursor.region()?;
7137            let start_overshoot = self.start.saturating_sub(region.range.start);
7138            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
7139                region.buffer_range.start + start_overshoot..region.buffer_range.end,
7140            ));
7141        }
7142
7143        if self.offset == region.range.end && region.has_trailing_newline {
7144            self.offset -= 1;
7145            Some("\n")
7146        } else {
7147            let chunk = self.current_chunks.as_mut().unwrap().next()?;
7148            self.offset -= chunk.len();
7149            Some(chunk)
7150        }
7151    }
7152}
7153
7154impl<'a> Iterator for MultiBufferChunks<'a> {
7155    type Item = Chunk<'a>;
7156
7157    fn next(&mut self) -> Option<Chunk<'a>> {
7158        if self.range.start >= self.range.end {
7159            return None;
7160        }
7161        if self.range.start == self.diff_transforms.end(&()).0 {
7162            self.diff_transforms.next(&());
7163        }
7164
7165        let diff_transform_start = self.diff_transforms.start().0;
7166        let diff_transform_end = self.diff_transforms.end(&()).0;
7167        debug_assert!(self.range.start < diff_transform_end);
7168
7169        let diff_transform = self.diff_transforms.item()?;
7170        match diff_transform {
7171            DiffTransform::BufferContent { .. } => {
7172                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
7173                    chunk
7174                } else {
7175                    let chunk = self.next_excerpt_chunk().unwrap();
7176                    self.buffer_chunk.insert(chunk)
7177                };
7178
7179                let chunk_end = self.range.start + chunk.text.len();
7180                let diff_transform_end = diff_transform_end.min(self.range.end);
7181
7182                if diff_transform_end < chunk_end {
7183                    let (before, after) =
7184                        chunk.text.split_at(diff_transform_end - self.range.start);
7185                    self.range.start = diff_transform_end;
7186                    chunk.text = after;
7187                    Some(Chunk {
7188                        text: before,
7189                        ..chunk.clone()
7190                    })
7191                } else {
7192                    self.range.start = chunk_end;
7193                    self.buffer_chunk.take()
7194                }
7195            }
7196            DiffTransform::DeletedHunk {
7197                buffer_id,
7198                base_text_byte_range,
7199                has_trailing_newline,
7200                ..
7201            } => {
7202                let base_text_start =
7203                    base_text_byte_range.start + self.range.start - diff_transform_start;
7204                let base_text_end =
7205                    base_text_byte_range.start + self.range.end - diff_transform_start;
7206                let base_text_end = base_text_end.min(base_text_byte_range.end);
7207
7208                let mut chunks = if let Some((_, mut chunks)) = self
7209                    .diff_base_chunks
7210                    .take()
7211                    .filter(|(id, _)| id == buffer_id)
7212                {
7213                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
7214                    {
7215                        chunks.seek(base_text_start..base_text_end);
7216                    }
7217                    chunks
7218                } else {
7219                    let base_buffer = &self.diffs.get(&buffer_id)?.base_text();
7220                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
7221                };
7222
7223                let chunk = if let Some(chunk) = chunks.next() {
7224                    self.range.start += chunk.text.len();
7225                    self.diff_base_chunks = Some((*buffer_id, chunks));
7226                    chunk
7227                } else {
7228                    debug_assert!(has_trailing_newline);
7229                    self.range.start += "\n".len();
7230                    Chunk {
7231                        text: "\n",
7232                        ..Default::default()
7233                    }
7234                };
7235                Some(chunk)
7236            }
7237        }
7238    }
7239}
7240
7241impl MultiBufferBytes<'_> {
7242    fn consume(&mut self, len: usize) {
7243        self.range.start += len;
7244        self.chunk = &self.chunk[len..];
7245
7246        if !self.range.is_empty() && self.chunk.is_empty() {
7247            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
7248                self.chunk = chunk;
7249            } else if self.has_trailing_newline {
7250                self.has_trailing_newline = false;
7251                self.chunk = b"\n";
7252            } else {
7253                self.cursor.next();
7254                if let Some(region) = self.cursor.region() {
7255                    let mut excerpt_bytes = region.buffer.bytes_in_range(
7256                        region.buffer_range.start
7257                            ..(region.buffer_range.start + self.range.end - region.range.start)
7258                                .min(region.buffer_range.end),
7259                    );
7260                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
7261                    self.excerpt_bytes = Some(excerpt_bytes);
7262                    self.has_trailing_newline =
7263                        region.has_trailing_newline && self.range.end >= region.range.end;
7264                    if self.chunk.is_empty() && self.has_trailing_newline {
7265                        self.has_trailing_newline = false;
7266                        self.chunk = b"\n";
7267                    }
7268                }
7269            }
7270        }
7271    }
7272}
7273
7274impl<'a> Iterator for MultiBufferBytes<'a> {
7275    type Item = &'a [u8];
7276
7277    fn next(&mut self) -> Option<Self::Item> {
7278        let chunk = self.chunk;
7279        if chunk.is_empty() {
7280            None
7281        } else {
7282            self.consume(chunk.len());
7283            Some(chunk)
7284        }
7285    }
7286}
7287
7288impl io::Read for MultiBufferBytes<'_> {
7289    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7290        let len = cmp::min(buf.len(), self.chunk.len());
7291        buf[..len].copy_from_slice(&self.chunk[..len]);
7292        if len > 0 {
7293            self.consume(len);
7294        }
7295        Ok(len)
7296    }
7297}
7298
7299impl io::Read for ReversedMultiBufferBytes<'_> {
7300    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
7301        let len = cmp::min(buf.len(), self.chunk.len());
7302        buf[..len].copy_from_slice(&self.chunk[..len]);
7303        buf[..len].reverse();
7304        if len > 0 {
7305            self.range.end -= len;
7306            self.chunk = &self.chunk[..self.chunk.len() - len];
7307            if !self.range.is_empty() && self.chunk.is_empty() {
7308                if let Some(chunk) = self.chunks.next() {
7309                    self.chunk = chunk.as_bytes();
7310                }
7311            }
7312        }
7313        Ok(len)
7314    }
7315}
7316
7317impl<'a> Iterator for ExcerptChunks<'a> {
7318    type Item = Chunk<'a>;
7319
7320    fn next(&mut self) -> Option<Self::Item> {
7321        if let Some(chunk) = self.content_chunks.next() {
7322            return Some(chunk);
7323        }
7324
7325        if self.footer_height > 0 {
7326            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
7327            self.footer_height = 0;
7328            return Some(Chunk {
7329                text,
7330                ..Default::default()
7331            });
7332        }
7333
7334        None
7335    }
7336}
7337
7338impl ToOffset for Point {
7339    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7340        snapshot.point_to_offset(*self)
7341    }
7342}
7343
7344impl ToOffset for usize {
7345    #[track_caller]
7346    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7347        assert!(*self <= snapshot.len(), "offset is out of range");
7348        *self
7349    }
7350}
7351
7352impl ToOffset for OffsetUtf16 {
7353    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7354        snapshot.offset_utf16_to_offset(*self)
7355    }
7356}
7357
7358impl ToOffset for PointUtf16 {
7359    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
7360        snapshot.point_utf16_to_offset(*self)
7361    }
7362}
7363
7364impl ToOffsetUtf16 for OffsetUtf16 {
7365    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7366        *self
7367    }
7368}
7369
7370impl ToOffsetUtf16 for usize {
7371    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
7372        snapshot.offset_to_offset_utf16(*self)
7373    }
7374}
7375
7376impl ToPoint for usize {
7377    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
7378        snapshot.offset_to_point(*self)
7379    }
7380}
7381
7382impl ToPoint for Point {
7383    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
7384        *self
7385    }
7386}
7387
7388impl ToPointUtf16 for usize {
7389    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7390        snapshot.offset_to_point_utf16(*self)
7391    }
7392}
7393
7394impl ToPointUtf16 for Point {
7395    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
7396        snapshot.point_to_point_utf16(*self)
7397    }
7398}
7399
7400impl ToPointUtf16 for PointUtf16 {
7401    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
7402        *self
7403    }
7404}
7405
7406impl From<ExcerptId> for EntityId {
7407    fn from(id: ExcerptId) -> Self {
7408        EntityId::from(id.0 as u64)
7409    }
7410}
7411
7412pub fn build_excerpt_ranges<T>(
7413    buffer: &BufferSnapshot,
7414    ranges: &[Range<T>],
7415    context_line_count: u32,
7416) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
7417where
7418    T: text::ToPoint,
7419{
7420    let max_point = buffer.max_point();
7421    let mut range_counts = Vec::new();
7422    let mut excerpt_ranges = Vec::new();
7423    let mut range_iter = ranges
7424        .iter()
7425        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
7426        .peekable();
7427    while let Some(range) = range_iter.next() {
7428        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
7429        let row = (range.end.row + context_line_count).min(max_point.row);
7430        let mut excerpt_end = Point::new(row, buffer.line_len(row));
7431
7432        let mut ranges_in_excerpt = 1;
7433
7434        while let Some(next_range) = range_iter.peek() {
7435            if next_range.start.row <= excerpt_end.row + context_line_count {
7436                let row = (next_range.end.row + context_line_count).min(max_point.row);
7437                excerpt_end = Point::new(row, buffer.line_len(row));
7438
7439                ranges_in_excerpt += 1;
7440                range_iter.next();
7441            } else {
7442                break;
7443            }
7444        }
7445
7446        excerpt_ranges.push(ExcerptRange {
7447            context: excerpt_start..excerpt_end,
7448            primary: Some(range),
7449        });
7450        range_counts.push(ranges_in_excerpt);
7451    }
7452
7453    (excerpt_ranges, range_counts)
7454}