multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt, Offset};
   4use anyhow::{anyhow, Result};
   5use clock::ReplicaId;
   6use collections::{BTreeMap, Bound, HashMap, HashSet};
   7use futures::{channel::mpsc, SinkExt};
   8use gpui::{AppContext, EntityId, EventEmitter, Model, ModelContext, Task};
   9use itertools::Itertools;
  10use language::{
  11    language_settings::{language_settings, LanguageSettings},
  12    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharClassifier,
  13    CharKind, Chunk, CursorShape, DiagnosticEntry, File, IndentGuide, IndentSize, Language,
  14    LanguageScope, OffsetRangeExt, OffsetUtf16, Outline, OutlineItem, Point, PointUtf16, Selection,
  15    TextDimension, ToOffset as _, ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _,
  16    TransactionId, Unclipped,
  17};
  18use smallvec::SmallVec;
  19use std::{
  20    any::type_name,
  21    borrow::Cow,
  22    cell::{Ref, RefCell},
  23    cmp, fmt,
  24    future::Future,
  25    io,
  26    iter::{self, FromIterator},
  27    mem,
  28    ops::{Range, RangeBounds, Sub},
  29    str,
  30    sync::Arc,
  31    time::{Duration, Instant},
  32};
  33use sum_tree::{Bias, Cursor, SumTree};
  34use text::{
  35    locator::Locator,
  36    subscription::{Subscription, Topic},
  37    BufferId, Edit, TextSummary,
  38};
  39use theme::SyntaxTheme;
  40
  41use util::post_inc;
  42
  43#[cfg(any(test, feature = "test-support"))]
  44use gpui::Context;
  45
  46const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  47
  48#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  49pub struct ExcerptId(usize);
  50
  51impl From<ExcerptId> for EntityId {
  52    fn from(id: ExcerptId) -> Self {
  53        EntityId::from(id.0 as u64)
  54    }
  55}
  56
  57/// One or more [`Buffers`](Buffer) being edited in a single view.
  58///
  59/// See <https://zed.dev/features#multi-buffers>
  60pub struct MultiBuffer {
  61    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  62    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  63    snapshot: RefCell<MultiBufferSnapshot>,
  64    /// Contains the state of the buffers being edited
  65    buffers: RefCell<HashMap<BufferId, BufferState>>,
  66    subscriptions: Topic,
  67    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  68    singleton: bool,
  69    history: History,
  70    title: Option<String>,
  71    capability: Capability,
  72}
  73
  74#[derive(Clone, Debug, PartialEq, Eq)]
  75pub enum Event {
  76    ExcerptsAdded {
  77        buffer: Model<Buffer>,
  78        predecessor: ExcerptId,
  79        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  80    },
  81    ExcerptsRemoved {
  82        ids: Vec<ExcerptId>,
  83    },
  84    ExcerptsExpanded {
  85        ids: Vec<ExcerptId>,
  86    },
  87    ExcerptsEdited {
  88        ids: Vec<ExcerptId>,
  89    },
  90    Edited {
  91        singleton_buffer_edited: bool,
  92    },
  93    TransactionUndone {
  94        transaction_id: TransactionId,
  95    },
  96    Reloaded,
  97    ReloadNeeded,
  98    DiffBaseChanged,
  99    DiffUpdated {
 100        buffer: Model<Buffer>,
 101    },
 102    LanguageChanged(BufferId),
 103    CapabilityChanged,
 104    Reparsed(BufferId),
 105    Saved,
 106    FileHandleChanged,
 107    Closed,
 108    Discarded,
 109    DirtyChanged,
 110    DiagnosticsUpdated,
 111}
 112
 113/// A diff hunk, representing a range of consequent lines in a multibuffer.
 114#[derive(Debug, Clone, PartialEq, Eq)]
 115pub struct MultiBufferDiffHunk {
 116    /// The row range in the multibuffer where this diff hunk appears.
 117    pub row_range: Range<MultiBufferRow>,
 118    /// The buffer ID that this hunk belongs to.
 119    pub buffer_id: BufferId,
 120    /// The range of the underlying buffer that this hunk corresponds to.
 121    pub buffer_range: Range<text::Anchor>,
 122    /// The range within the buffer's diff base that this hunk corresponds to.
 123    pub diff_base_byte_range: Range<usize>,
 124}
 125
 126pub type MultiBufferPoint = Point;
 127
 128#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, serde::Deserialize)]
 129#[serde(transparent)]
 130pub struct MultiBufferRow(pub u32);
 131
 132impl MultiBufferRow {
 133    pub const MIN: Self = Self(0);
 134    pub const MAX: Self = Self(u32::MAX);
 135}
 136
 137#[derive(Clone)]
 138struct History {
 139    next_transaction_id: TransactionId,
 140    undo_stack: Vec<Transaction>,
 141    redo_stack: Vec<Transaction>,
 142    transaction_depth: usize,
 143    group_interval: Duration,
 144}
 145
 146#[derive(Clone)]
 147struct Transaction {
 148    id: TransactionId,
 149    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 150    first_edit_at: Instant,
 151    last_edit_at: Instant,
 152    suppress_grouping: bool,
 153}
 154
 155pub trait ToOffset: 'static + fmt::Debug {
 156    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 157}
 158
 159pub trait ToOffsetUtf16: 'static + fmt::Debug {
 160    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 161}
 162
 163pub trait ToPoint: 'static + fmt::Debug {
 164    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 165}
 166
 167pub trait ToPointUtf16: 'static + fmt::Debug {
 168    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 169}
 170
 171struct BufferState {
 172    buffer: Model<Buffer>,
 173    last_version: clock::Global,
 174    last_non_text_state_update_count: usize,
 175    excerpts: Vec<Locator>,
 176    _subscriptions: [gpui::Subscription; 2],
 177}
 178
 179/// The contents of a [`MultiBuffer`] at a single point in time.
 180#[derive(Clone, Default)]
 181pub struct MultiBufferSnapshot {
 182    singleton: bool,
 183    excerpts: SumTree<Excerpt>,
 184    excerpt_ids: SumTree<ExcerptIdMapping>,
 185    trailing_excerpt_update_count: usize,
 186    non_text_state_update_count: usize,
 187    edit_count: usize,
 188    is_dirty: bool,
 189    has_conflict: bool,
 190    show_headers: bool,
 191}
 192
 193#[derive(Clone)]
 194pub struct ExcerptInfo {
 195    pub id: ExcerptId,
 196    pub buffer: BufferSnapshot,
 197    pub buffer_id: BufferId,
 198    pub range: ExcerptRange<text::Anchor>,
 199}
 200
 201impl std::fmt::Debug for ExcerptInfo {
 202    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 203        f.debug_struct(type_name::<Self>())
 204            .field("id", &self.id)
 205            .field("buffer_id", &self.buffer_id)
 206            .field("path", &self.buffer.file().map(|f| f.path()))
 207            .field("range", &self.range)
 208            .finish()
 209    }
 210}
 211
 212/// A boundary between [`Excerpt`]s in a [`MultiBuffer`]
 213#[derive(Debug)]
 214pub struct ExcerptBoundary {
 215    pub prev: Option<ExcerptInfo>,
 216    pub next: Option<ExcerptInfo>,
 217    /// The row in the `MultiBuffer` where the boundary is located
 218    pub row: MultiBufferRow,
 219}
 220
 221impl ExcerptBoundary {
 222    pub fn starts_new_buffer(&self) -> bool {
 223        match (self.prev.as_ref(), self.next.as_ref()) {
 224            (None, _) => true,
 225            (Some(_), None) => false,
 226            (Some(prev), Some(next)) => prev.buffer_id != next.buffer_id,
 227        }
 228    }
 229}
 230
 231/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 232#[derive(Clone)]
 233struct Excerpt {
 234    /// The unique identifier for this excerpt
 235    id: ExcerptId,
 236    /// The location of the excerpt in the [`MultiBuffer`]
 237    locator: Locator,
 238    /// The buffer being excerpted
 239    buffer_id: BufferId,
 240    /// A snapshot of the buffer being excerpted
 241    buffer: BufferSnapshot,
 242    /// The range of the buffer to be shown in the excerpt
 243    range: ExcerptRange<text::Anchor>,
 244    /// The last row in the excerpted slice of the buffer
 245    max_buffer_row: BufferRow,
 246    /// A summary of the text in the excerpt
 247    text_summary: TextSummary,
 248    has_trailing_newline: bool,
 249}
 250
 251/// A public view into an [`Excerpt`] in a [`MultiBuffer`].
 252///
 253/// Contains methods for getting the [`Buffer`] of the excerpt,
 254/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 255#[derive(Clone)]
 256pub struct MultiBufferExcerpt<'a> {
 257    excerpt: &'a Excerpt,
 258    excerpt_offset: usize,
 259}
 260
 261#[derive(Clone, Debug)]
 262struct ExcerptIdMapping {
 263    id: ExcerptId,
 264    locator: Locator,
 265}
 266
 267/// A range of text from a single [`Buffer`], to be shown as an [`Excerpt`].
 268/// These ranges are relative to the buffer itself
 269#[derive(Clone, Debug, Eq, PartialEq)]
 270pub struct ExcerptRange<T> {
 271    /// The full range of text to be shown in the excerpt.
 272    pub context: Range<T>,
 273    /// The primary range of text to be highlighted in the excerpt.
 274    /// In a multi-buffer search, this would be the text that matched the search
 275    pub primary: Option<Range<T>>,
 276}
 277
 278#[derive(Clone, Debug, Default)]
 279pub struct ExcerptSummary {
 280    excerpt_id: ExcerptId,
 281    /// The location of the last [`Excerpt`] being summarized
 282    excerpt_locator: Locator,
 283    /// The maximum row of the [`Excerpt`]s being summarized
 284    max_buffer_row: MultiBufferRow,
 285    text: TextSummary,
 286}
 287
 288#[derive(Clone)]
 289pub struct MultiBufferRows<'a> {
 290    buffer_row_range: Range<u32>,
 291    excerpts: Cursor<'a, Excerpt, Point>,
 292}
 293
 294pub struct MultiBufferChunks<'a> {
 295    range: Range<usize>,
 296    excerpts: Cursor<'a, Excerpt, usize>,
 297    excerpt_chunks: Option<ExcerptChunks<'a>>,
 298    language_aware: bool,
 299}
 300
 301pub struct MultiBufferBytes<'a> {
 302    range: Range<usize>,
 303    excerpts: Cursor<'a, Excerpt, usize>,
 304    excerpt_bytes: Option<ExcerptBytes<'a>>,
 305    chunk: &'a [u8],
 306}
 307
 308pub struct ReversedMultiBufferBytes<'a> {
 309    range: Range<usize>,
 310    excerpts: Cursor<'a, Excerpt, usize>,
 311    excerpt_bytes: Option<ExcerptBytes<'a>>,
 312    chunk: &'a [u8],
 313}
 314
 315struct ExcerptChunks<'a> {
 316    excerpt_id: ExcerptId,
 317    content_chunks: BufferChunks<'a>,
 318    footer_height: usize,
 319}
 320
 321struct ExcerptBytes<'a> {
 322    content_bytes: text::Bytes<'a>,
 323    padding_height: usize,
 324    reversed: bool,
 325}
 326
 327#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 328pub enum ExpandExcerptDirection {
 329    Up,
 330    Down,
 331    UpAndDown,
 332}
 333
 334impl ExpandExcerptDirection {
 335    pub fn should_expand_up(&self) -> bool {
 336        match self {
 337            ExpandExcerptDirection::Up => true,
 338            ExpandExcerptDirection::Down => false,
 339            ExpandExcerptDirection::UpAndDown => true,
 340        }
 341    }
 342
 343    pub fn should_expand_down(&self) -> bool {
 344        match self {
 345            ExpandExcerptDirection::Up => false,
 346            ExpandExcerptDirection::Down => true,
 347            ExpandExcerptDirection::UpAndDown => true,
 348        }
 349    }
 350}
 351
 352#[derive(Clone, Debug, PartialEq)]
 353pub struct MultiBufferIndentGuide {
 354    pub multibuffer_row_range: Range<MultiBufferRow>,
 355    pub buffer: IndentGuide,
 356}
 357
 358impl std::ops::Deref for MultiBufferIndentGuide {
 359    type Target = IndentGuide;
 360
 361    fn deref(&self) -> &Self::Target {
 362        &self.buffer
 363    }
 364}
 365
 366impl MultiBuffer {
 367    pub fn new(capability: Capability) -> Self {
 368        Self {
 369            snapshot: RefCell::new(MultiBufferSnapshot {
 370                show_headers: true,
 371                ..MultiBufferSnapshot::default()
 372            }),
 373            buffers: RefCell::default(),
 374            subscriptions: Topic::default(),
 375            singleton: false,
 376            capability,
 377            title: None,
 378            history: History {
 379                next_transaction_id: clock::Lamport::default(),
 380                undo_stack: Vec::new(),
 381                redo_stack: Vec::new(),
 382                transaction_depth: 0,
 383                group_interval: Duration::from_millis(300),
 384            },
 385        }
 386    }
 387
 388    pub fn without_headers(capability: Capability) -> Self {
 389        Self {
 390            snapshot: Default::default(),
 391            buffers: Default::default(),
 392            subscriptions: Default::default(),
 393            singleton: false,
 394            capability,
 395            history: History {
 396                next_transaction_id: Default::default(),
 397                undo_stack: Default::default(),
 398                redo_stack: Default::default(),
 399                transaction_depth: 0,
 400                group_interval: Duration::from_millis(300),
 401            },
 402            title: Default::default(),
 403        }
 404    }
 405
 406    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 407        let mut buffers = HashMap::default();
 408        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 409            buffers.insert(
 410                *buffer_id,
 411                BufferState {
 412                    buffer: buffer_state.buffer.clone(),
 413                    last_version: buffer_state.last_version.clone(),
 414                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 415                    excerpts: buffer_state.excerpts.clone(),
 416                    _subscriptions: [
 417                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 418                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 419                    ],
 420                },
 421            );
 422        }
 423        Self {
 424            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 425            buffers: RefCell::new(buffers),
 426            subscriptions: Default::default(),
 427            singleton: self.singleton,
 428            capability: self.capability,
 429            history: self.history.clone(),
 430            title: self.title.clone(),
 431        }
 432    }
 433
 434    pub fn with_title(mut self, title: String) -> Self {
 435        self.title = Some(title);
 436        self
 437    }
 438
 439    pub fn read_only(&self) -> bool {
 440        self.capability == Capability::ReadOnly
 441    }
 442
 443    pub fn singleton(buffer: Model<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 444        let mut this = Self::new(buffer.read(cx).capability());
 445        this.singleton = true;
 446        this.push_excerpts(
 447            buffer,
 448            [ExcerptRange {
 449                context: text::Anchor::MIN..text::Anchor::MAX,
 450                primary: None,
 451            }],
 452            cx,
 453        );
 454        this.snapshot.borrow_mut().singleton = true;
 455        this
 456    }
 457
 458    /// Returns an up-to-date snapshot of the MultiBuffer.
 459    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 460        self.sync(cx);
 461        self.snapshot.borrow().clone()
 462    }
 463
 464    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 465        self.sync(cx);
 466        self.snapshot.borrow()
 467    }
 468
 469    pub fn as_singleton(&self) -> Option<Model<Buffer>> {
 470        if self.singleton {
 471            return Some(
 472                self.buffers
 473                    .borrow()
 474                    .values()
 475                    .next()
 476                    .unwrap()
 477                    .buffer
 478                    .clone(),
 479            );
 480        } else {
 481            None
 482        }
 483    }
 484
 485    pub fn is_singleton(&self) -> bool {
 486        self.singleton
 487    }
 488
 489    pub fn subscribe(&mut self) -> Subscription {
 490        self.subscriptions.subscribe()
 491    }
 492
 493    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 494        self.read(cx).is_dirty()
 495    }
 496
 497    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 498        self.read(cx).has_conflict()
 499    }
 500
 501    // The `is_empty` signature doesn't match what clippy expects
 502    #[allow(clippy::len_without_is_empty)]
 503    pub fn len(&self, cx: &AppContext) -> usize {
 504        self.read(cx).len()
 505    }
 506
 507    pub fn is_empty(&self, cx: &AppContext) -> bool {
 508        self.len(cx) != 0
 509    }
 510
 511    pub fn symbols_containing<T: ToOffset>(
 512        &self,
 513        offset: T,
 514        theme: Option<&SyntaxTheme>,
 515        cx: &AppContext,
 516    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 517        self.read(cx).symbols_containing(offset, theme)
 518    }
 519
 520    pub fn edit<I, S, T>(
 521        &self,
 522        edits: I,
 523        mut autoindent_mode: Option<AutoindentMode>,
 524        cx: &mut ModelContext<Self>,
 525    ) where
 526        I: IntoIterator<Item = (Range<S>, T)>,
 527        S: ToOffset,
 528        T: Into<Arc<str>>,
 529    {
 530        if self.read_only() {
 531            return;
 532        }
 533        if self.buffers.borrow().is_empty() {
 534            return;
 535        }
 536
 537        let snapshot = self.read(cx);
 538        let edits = edits.into_iter().map(|(range, new_text)| {
 539            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 540            if range.start > range.end {
 541                mem::swap(&mut range.start, &mut range.end);
 542            }
 543            (range, new_text)
 544        });
 545
 546        if let Some(buffer) = self.as_singleton() {
 547            buffer.update(cx, |buffer, cx| {
 548                buffer.edit(edits, autoindent_mode, cx);
 549            });
 550            cx.emit(Event::ExcerptsEdited {
 551                ids: self.excerpt_ids(),
 552            });
 553            return;
 554        }
 555
 556        let original_indent_columns = match &mut autoindent_mode {
 557            Some(AutoindentMode::Block {
 558                original_indent_columns,
 559            }) => mem::take(original_indent_columns),
 560            _ => Default::default(),
 561        };
 562
 563        struct BufferEdit {
 564            range: Range<usize>,
 565            new_text: Arc<str>,
 566            is_insertion: bool,
 567            original_indent_column: u32,
 568        }
 569        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 570        let mut edited_excerpt_ids = Vec::new();
 571        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
 572        for (ix, (range, new_text)) in edits.enumerate() {
 573            let new_text: Arc<str> = new_text.into();
 574            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 575            cursor.seek(&range.start, Bias::Right, &());
 576            if cursor.item().is_none() && range.start == *cursor.start() {
 577                cursor.prev(&());
 578            }
 579            let start_excerpt = cursor.item().expect("start offset out of bounds");
 580            let start_overshoot = range.start - cursor.start();
 581            let buffer_start = start_excerpt
 582                .range
 583                .context
 584                .start
 585                .to_offset(&start_excerpt.buffer)
 586                + start_overshoot;
 587            edited_excerpt_ids.push(start_excerpt.id);
 588
 589            cursor.seek(&range.end, Bias::Right, &());
 590            if cursor.item().is_none() && range.end == *cursor.start() {
 591                cursor.prev(&());
 592            }
 593            let end_excerpt = cursor.item().expect("end offset out of bounds");
 594            let end_overshoot = range.end - cursor.start();
 595            let buffer_end = end_excerpt
 596                .range
 597                .context
 598                .start
 599                .to_offset(&end_excerpt.buffer)
 600                + end_overshoot;
 601
 602            if start_excerpt.id == end_excerpt.id {
 603                buffer_edits
 604                    .entry(start_excerpt.buffer_id)
 605                    .or_default()
 606                    .push(BufferEdit {
 607                        range: buffer_start..buffer_end,
 608                        new_text,
 609                        is_insertion: true,
 610                        original_indent_column,
 611                    });
 612            } else {
 613                edited_excerpt_ids.push(end_excerpt.id);
 614                let start_excerpt_range = buffer_start
 615                    ..start_excerpt
 616                        .range
 617                        .context
 618                        .end
 619                        .to_offset(&start_excerpt.buffer);
 620                let end_excerpt_range = end_excerpt
 621                    .range
 622                    .context
 623                    .start
 624                    .to_offset(&end_excerpt.buffer)
 625                    ..buffer_end;
 626                buffer_edits
 627                    .entry(start_excerpt.buffer_id)
 628                    .or_default()
 629                    .push(BufferEdit {
 630                        range: start_excerpt_range,
 631                        new_text: new_text.clone(),
 632                        is_insertion: true,
 633                        original_indent_column,
 634                    });
 635                buffer_edits
 636                    .entry(end_excerpt.buffer_id)
 637                    .or_default()
 638                    .push(BufferEdit {
 639                        range: end_excerpt_range,
 640                        new_text: new_text.clone(),
 641                        is_insertion: false,
 642                        original_indent_column,
 643                    });
 644
 645                cursor.seek(&range.start, Bias::Right, &());
 646                cursor.next(&());
 647                while let Some(excerpt) = cursor.item() {
 648                    if excerpt.id == end_excerpt.id {
 649                        break;
 650                    }
 651                    buffer_edits
 652                        .entry(excerpt.buffer_id)
 653                        .or_default()
 654                        .push(BufferEdit {
 655                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 656                            new_text: new_text.clone(),
 657                            is_insertion: false,
 658                            original_indent_column,
 659                        });
 660                    edited_excerpt_ids.push(excerpt.id);
 661                    cursor.next(&());
 662                }
 663            }
 664        }
 665
 666        drop(cursor);
 667        drop(snapshot);
 668        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 669        fn tail(
 670            this: &MultiBuffer,
 671            buffer_edits: HashMap<BufferId, Vec<BufferEdit>>,
 672            autoindent_mode: Option<AutoindentMode>,
 673            edited_excerpt_ids: Vec<ExcerptId>,
 674            cx: &mut ModelContext<MultiBuffer>,
 675        ) {
 676            for (buffer_id, mut edits) in buffer_edits {
 677                edits.sort_unstable_by_key(|edit| edit.range.start);
 678                this.buffers.borrow()[&buffer_id]
 679                    .buffer
 680                    .update(cx, |buffer, cx| {
 681                        let mut edits = edits.into_iter().peekable();
 682                        let mut insertions = Vec::new();
 683                        let mut original_indent_columns = Vec::new();
 684                        let mut deletions = Vec::new();
 685                        let empty_str: Arc<str> = Arc::default();
 686                        while let Some(BufferEdit {
 687                            mut range,
 688                            new_text,
 689                            mut is_insertion,
 690                            original_indent_column,
 691                        }) = edits.next()
 692                        {
 693                            while let Some(BufferEdit {
 694                                range: next_range,
 695                                is_insertion: next_is_insertion,
 696                                ..
 697                            }) = edits.peek()
 698                            {
 699                                if range.end >= next_range.start {
 700                                    range.end = cmp::max(next_range.end, range.end);
 701                                    is_insertion |= *next_is_insertion;
 702                                    edits.next();
 703                                } else {
 704                                    break;
 705                                }
 706                            }
 707
 708                            if is_insertion {
 709                                original_indent_columns.push(original_indent_column);
 710                                insertions.push((
 711                                    buffer.anchor_before(range.start)
 712                                        ..buffer.anchor_before(range.end),
 713                                    new_text.clone(),
 714                                ));
 715                            } else if !range.is_empty() {
 716                                deletions.push((
 717                                    buffer.anchor_before(range.start)
 718                                        ..buffer.anchor_before(range.end),
 719                                    empty_str.clone(),
 720                                ));
 721                            }
 722                        }
 723
 724                        let deletion_autoindent_mode =
 725                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 726                                Some(AutoindentMode::Block {
 727                                    original_indent_columns: Default::default(),
 728                                })
 729                            } else {
 730                                autoindent_mode.clone()
 731                            };
 732                        let insertion_autoindent_mode =
 733                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 734                                Some(AutoindentMode::Block {
 735                                    original_indent_columns,
 736                                })
 737                            } else {
 738                                autoindent_mode.clone()
 739                            };
 740
 741                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 742                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 743                    })
 744            }
 745
 746            cx.emit(Event::ExcerptsEdited {
 747                ids: edited_excerpt_ids,
 748            });
 749        }
 750        tail(self, buffer_edits, autoindent_mode, edited_excerpt_ids, cx);
 751    }
 752
 753    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
 754    // You can also request the insertion of empty lines above and below the line starting at the returned point.
 755    // Panics if the given position is invalid.
 756    pub fn insert_empty_line(
 757        &mut self,
 758        position: impl ToPoint,
 759        space_above: bool,
 760        space_below: bool,
 761        cx: &mut ModelContext<Self>,
 762    ) -> Point {
 763        let multibuffer_point = position.to_point(&self.read(cx));
 764        if let Some(buffer) = self.as_singleton() {
 765            buffer.update(cx, |buffer, cx| {
 766                buffer.insert_empty_line(multibuffer_point, space_above, space_below, cx)
 767            })
 768        } else {
 769            let (buffer, buffer_point, _) =
 770                self.point_to_buffer_point(multibuffer_point, cx).unwrap();
 771            self.start_transaction(cx);
 772            let empty_line_start = buffer.update(cx, |buffer, cx| {
 773                buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
 774            });
 775            self.end_transaction(cx);
 776            multibuffer_point + (empty_line_start - buffer_point)
 777        }
 778    }
 779
 780    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 781        self.start_transaction_at(Instant::now(), cx)
 782    }
 783
 784    pub fn start_transaction_at(
 785        &mut self,
 786        now: Instant,
 787        cx: &mut ModelContext<Self>,
 788    ) -> Option<TransactionId> {
 789        if let Some(buffer) = self.as_singleton() {
 790            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 791        }
 792
 793        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 794            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 795        }
 796        self.history.start_transaction(now)
 797    }
 798
 799    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 800        self.end_transaction_at(Instant::now(), cx)
 801    }
 802
 803    pub fn end_transaction_at(
 804        &mut self,
 805        now: Instant,
 806        cx: &mut ModelContext<Self>,
 807    ) -> Option<TransactionId> {
 808        if let Some(buffer) = self.as_singleton() {
 809            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 810        }
 811
 812        let mut buffer_transactions = HashMap::default();
 813        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 814            if let Some(transaction_id) =
 815                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 816            {
 817                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 818            }
 819        }
 820
 821        if self.history.end_transaction(now, buffer_transactions) {
 822            let transaction_id = self.history.group().unwrap();
 823            Some(transaction_id)
 824        } else {
 825            None
 826        }
 827    }
 828
 829    pub fn edited_ranges_for_transaction<D>(
 830        &self,
 831        transaction_id: TransactionId,
 832        cx: &AppContext,
 833    ) -> Vec<Range<D>>
 834    where
 835        D: TextDimension + Ord + Sub<D, Output = D>,
 836    {
 837        if let Some(buffer) = self.as_singleton() {
 838            return buffer
 839                .read(cx)
 840                .edited_ranges_for_transaction_id(transaction_id)
 841                .collect::<Vec<_>>();
 842        }
 843
 844        let Some(transaction) = self.history.transaction(transaction_id) else {
 845            return Vec::new();
 846        };
 847
 848        let mut ranges = Vec::new();
 849        let snapshot = self.read(cx);
 850        let buffers = self.buffers.borrow();
 851        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(&());
 852
 853        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
 854            let Some(buffer_state) = buffers.get(buffer_id) else {
 855                continue;
 856            };
 857
 858            let buffer = buffer_state.buffer.read(cx);
 859            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
 860                for excerpt_id in &buffer_state.excerpts {
 861                    cursor.seek(excerpt_id, Bias::Left, &());
 862                    if let Some(excerpt) = cursor.item() {
 863                        if excerpt.locator == *excerpt_id {
 864                            let excerpt_buffer_start =
 865                                excerpt.range.context.start.summary::<D>(buffer);
 866                            let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
 867                            let excerpt_range = excerpt_buffer_start.clone()..excerpt_buffer_end;
 868                            if excerpt_range.contains(&range.start)
 869                                && excerpt_range.contains(&range.end)
 870                            {
 871                                let excerpt_start = D::from_text_summary(&cursor.start().text);
 872
 873                                let mut start = excerpt_start.clone();
 874                                start.add_assign(&(range.start - excerpt_buffer_start.clone()));
 875                                let mut end = excerpt_start;
 876                                end.add_assign(&(range.end - excerpt_buffer_start));
 877
 878                                ranges.push(start..end);
 879                                break;
 880                            }
 881                        }
 882                    }
 883                }
 884            }
 885        }
 886
 887        ranges.sort_by_key(|range| range.start.clone());
 888        ranges
 889    }
 890
 891    pub fn merge_transactions(
 892        &mut self,
 893        transaction: TransactionId,
 894        destination: TransactionId,
 895        cx: &mut ModelContext<Self>,
 896    ) {
 897        if let Some(buffer) = self.as_singleton() {
 898            buffer.update(cx, |buffer, _| {
 899                buffer.merge_transactions(transaction, destination)
 900            });
 901        } else if let Some(transaction) = self.history.forget(transaction) {
 902            if let Some(destination) = self.history.transaction_mut(destination) {
 903                for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
 904                    if let Some(destination_buffer_transaction_id) =
 905                        destination.buffer_transactions.get(&buffer_id)
 906                    {
 907                        if let Some(state) = self.buffers.borrow().get(&buffer_id) {
 908                            state.buffer.update(cx, |buffer, _| {
 909                                buffer.merge_transactions(
 910                                    buffer_transaction_id,
 911                                    *destination_buffer_transaction_id,
 912                                )
 913                            });
 914                        }
 915                    } else {
 916                        destination
 917                            .buffer_transactions
 918                            .insert(buffer_id, buffer_transaction_id);
 919                    }
 920                }
 921            }
 922        }
 923    }
 924
 925    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 926        self.history.finalize_last_transaction();
 927        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 928            buffer.update(cx, |buffer, _| {
 929                buffer.finalize_last_transaction();
 930            });
 931        }
 932    }
 933
 934    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &ModelContext<Self>)
 935    where
 936        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
 937    {
 938        self.history
 939            .push_transaction(buffer_transactions, Instant::now(), cx);
 940        self.history.finalize_last_transaction();
 941    }
 942
 943    pub fn group_until_transaction(
 944        &mut self,
 945        transaction_id: TransactionId,
 946        cx: &mut ModelContext<Self>,
 947    ) {
 948        if let Some(buffer) = self.as_singleton() {
 949            buffer.update(cx, |buffer, _| {
 950                buffer.group_until_transaction(transaction_id)
 951            });
 952        } else {
 953            self.history.group_until(transaction_id);
 954        }
 955    }
 956
 957    pub fn set_active_selections(
 958        &self,
 959        selections: &[Selection<Anchor>],
 960        line_mode: bool,
 961        cursor_shape: CursorShape,
 962        cx: &mut ModelContext<Self>,
 963    ) {
 964        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
 965            Default::default();
 966        let snapshot = self.read(cx);
 967        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
 968        for selection in selections {
 969            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 970            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 971
 972            cursor.seek(&Some(start_locator), Bias::Left, &());
 973            while let Some(excerpt) = cursor.item() {
 974                if excerpt.locator > *end_locator {
 975                    break;
 976                }
 977
 978                let mut start = excerpt.range.context.start;
 979                let mut end = excerpt.range.context.end;
 980                if excerpt.id == selection.start.excerpt_id {
 981                    start = selection.start.text_anchor;
 982                }
 983                if excerpt.id == selection.end.excerpt_id {
 984                    end = selection.end.text_anchor;
 985                }
 986                selections_by_buffer
 987                    .entry(excerpt.buffer_id)
 988                    .or_default()
 989                    .push(Selection {
 990                        id: selection.id,
 991                        start,
 992                        end,
 993                        reversed: selection.reversed,
 994                        goal: selection.goal,
 995                    });
 996
 997                cursor.next(&());
 998            }
 999        }
1000
1001        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1002            if !selections_by_buffer.contains_key(buffer_id) {
1003                buffer_state
1004                    .buffer
1005                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1006            }
1007        }
1008
1009        for (buffer_id, mut selections) in selections_by_buffer {
1010            self.buffers.borrow()[&buffer_id]
1011                .buffer
1012                .update(cx, |buffer, cx| {
1013                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1014                    let mut selections = selections.into_iter().peekable();
1015                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1016                        let mut selection = selections.next()?;
1017                        while let Some(next_selection) = selections.peek() {
1018                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1019                                let next_selection = selections.next().unwrap();
1020                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1021                                    selection.end = next_selection.end;
1022                                }
1023                            } else {
1024                                break;
1025                            }
1026                        }
1027                        Some(selection)
1028                    }));
1029                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1030                });
1031        }
1032    }
1033
1034    pub fn remove_active_selections(&self, cx: &mut ModelContext<Self>) {
1035        for buffer in self.buffers.borrow().values() {
1036            buffer
1037                .buffer
1038                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1039        }
1040    }
1041
1042    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
1043        let mut transaction_id = None;
1044        if let Some(buffer) = self.as_singleton() {
1045            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1046        } else {
1047            while let Some(transaction) = self.history.pop_undo() {
1048                let mut undone = false;
1049                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1050                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1051                        undone |= buffer.update(cx, |buffer, cx| {
1052                            let undo_to = *buffer_transaction_id;
1053                            if let Some(entry) = buffer.peek_undo_stack() {
1054                                *buffer_transaction_id = entry.transaction_id();
1055                            }
1056                            buffer.undo_to_transaction(undo_to, cx)
1057                        });
1058                    }
1059                }
1060
1061                if undone {
1062                    transaction_id = Some(transaction.id);
1063                    break;
1064                }
1065            }
1066        }
1067
1068        if let Some(transaction_id) = transaction_id {
1069            cx.emit(Event::TransactionUndone { transaction_id });
1070        }
1071
1072        transaction_id
1073    }
1074
1075    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
1076        if let Some(buffer) = self.as_singleton() {
1077            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1078        }
1079
1080        while let Some(transaction) = self.history.pop_redo() {
1081            let mut redone = false;
1082            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1083                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1084                    redone |= buffer.update(cx, |buffer, cx| {
1085                        let redo_to = *buffer_transaction_id;
1086                        if let Some(entry) = buffer.peek_redo_stack() {
1087                            *buffer_transaction_id = entry.transaction_id();
1088                        }
1089                        buffer.redo_to_transaction(redo_to, cx)
1090                    });
1091                }
1092            }
1093
1094            if redone {
1095                return Some(transaction.id);
1096            }
1097        }
1098
1099        None
1100    }
1101
1102    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
1103        if let Some(buffer) = self.as_singleton() {
1104            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1105        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1106            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1107                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1108                    buffer.update(cx, |buffer, cx| {
1109                        buffer.undo_transaction(*transaction_id, cx)
1110                    });
1111                }
1112            }
1113        }
1114    }
1115
1116    pub fn forget_transaction(
1117        &mut self,
1118        transaction_id: TransactionId,
1119        cx: &mut ModelContext<Self>,
1120    ) {
1121        if let Some(buffer) = self.as_singleton() {
1122            buffer.update(cx, |buffer, _| {
1123                buffer.forget_transaction(transaction_id);
1124            });
1125        } else if let Some(transaction) = self.history.forget(transaction_id) {
1126            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1127                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1128                    state.buffer.update(cx, |buffer, _| {
1129                        buffer.forget_transaction(buffer_transaction_id);
1130                    });
1131                }
1132            }
1133        }
1134    }
1135
1136    pub fn push_excerpts<O>(
1137        &mut self,
1138        buffer: Model<Buffer>,
1139        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1140        cx: &mut ModelContext<Self>,
1141    ) -> Vec<ExcerptId>
1142    where
1143        O: text::ToOffset,
1144    {
1145        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1146    }
1147
1148    pub fn push_excerpts_with_context_lines<O>(
1149        &mut self,
1150        buffer: Model<Buffer>,
1151        ranges: Vec<Range<O>>,
1152        context_line_count: u32,
1153        cx: &mut ModelContext<Self>,
1154    ) -> Vec<Range<Anchor>>
1155    where
1156        O: text::ToPoint + text::ToOffset,
1157    {
1158        let buffer_id = buffer.read(cx).remote_id();
1159        let buffer_snapshot = buffer.read(cx).snapshot();
1160        let (excerpt_ranges, range_counts) =
1161            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
1162
1163        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
1164
1165        let mut anchor_ranges = Vec::new();
1166        let mut ranges = ranges.into_iter();
1167        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
1168            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
1169                let start = Anchor {
1170                    buffer_id: Some(buffer_id),
1171                    excerpt_id,
1172                    text_anchor: buffer_snapshot.anchor_after(range.start),
1173                };
1174                let end = Anchor {
1175                    buffer_id: Some(buffer_id),
1176                    excerpt_id,
1177                    text_anchor: buffer_snapshot.anchor_after(range.end),
1178                };
1179                start..end
1180            }))
1181        }
1182        anchor_ranges
1183    }
1184
1185    pub fn push_multiple_excerpts_with_context_lines(
1186        &self,
1187        buffers_with_ranges: Vec<(Model<Buffer>, Vec<Range<text::Anchor>>)>,
1188        context_line_count: u32,
1189        cx: &mut ModelContext<Self>,
1190    ) -> Task<Vec<Range<Anchor>>> {
1191        use futures::StreamExt;
1192
1193        let (excerpt_ranges_tx, mut excerpt_ranges_rx) = mpsc::channel(256);
1194
1195        let mut buffer_ids = Vec::with_capacity(buffers_with_ranges.len());
1196
1197        for (buffer, ranges) in buffers_with_ranges {
1198            let (buffer_id, buffer_snapshot) =
1199                buffer.update(cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
1200
1201            buffer_ids.push(buffer_id);
1202
1203            cx.background_executor()
1204                .spawn({
1205                    let mut excerpt_ranges_tx = excerpt_ranges_tx.clone();
1206
1207                    async move {
1208                        let (excerpt_ranges, counts) =
1209                            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
1210                        excerpt_ranges_tx
1211                            .send((buffer_id, buffer.clone(), ranges, excerpt_ranges, counts))
1212                            .await
1213                            .ok();
1214                    }
1215                })
1216                .detach()
1217        }
1218
1219        cx.spawn(move |this, mut cx| async move {
1220            let mut results_by_buffer_id = HashMap::default();
1221            while let Some((buffer_id, buffer, ranges, excerpt_ranges, range_counts)) =
1222                excerpt_ranges_rx.next().await
1223            {
1224                results_by_buffer_id
1225                    .insert(buffer_id, (buffer, ranges, excerpt_ranges, range_counts));
1226            }
1227
1228            let mut multi_buffer_ranges = Vec::default();
1229            'outer: for buffer_id in buffer_ids {
1230                let Some((buffer, ranges, excerpt_ranges, range_counts)) =
1231                    results_by_buffer_id.remove(&buffer_id)
1232                else {
1233                    continue;
1234                };
1235
1236                let mut ranges = ranges.into_iter();
1237                let mut range_counts = range_counts.into_iter();
1238                for excerpt_ranges in excerpt_ranges.chunks(100) {
1239                    let excerpt_ids = match this.update(&mut cx, |this, cx| {
1240                        this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
1241                    }) {
1242                        Ok(excerpt_ids) => excerpt_ids,
1243                        Err(_) => continue 'outer,
1244                    };
1245
1246                    for (excerpt_id, range_count) in
1247                        excerpt_ids.into_iter().zip(range_counts.by_ref())
1248                    {
1249                        for range in ranges.by_ref().take(range_count) {
1250                            let start = Anchor {
1251                                buffer_id: Some(buffer_id),
1252                                excerpt_id,
1253                                text_anchor: range.start,
1254                            };
1255                            let end = Anchor {
1256                                buffer_id: Some(buffer_id),
1257                                excerpt_id,
1258                                text_anchor: range.end,
1259                            };
1260                            multi_buffer_ranges.push(start..end);
1261                        }
1262                    }
1263                }
1264            }
1265
1266            multi_buffer_ranges
1267        })
1268    }
1269
1270    pub fn insert_excerpts_after<O>(
1271        &mut self,
1272        prev_excerpt_id: ExcerptId,
1273        buffer: Model<Buffer>,
1274        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1275        cx: &mut ModelContext<Self>,
1276    ) -> Vec<ExcerptId>
1277    where
1278        O: text::ToOffset,
1279    {
1280        let mut ids = Vec::new();
1281        let mut next_excerpt_id =
1282            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1283                last_entry.id.0 + 1
1284            } else {
1285                1
1286            };
1287        self.insert_excerpts_with_ids_after(
1288            prev_excerpt_id,
1289            buffer,
1290            ranges.into_iter().map(|range| {
1291                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1292                ids.push(id);
1293                (id, range)
1294            }),
1295            cx,
1296        );
1297        ids
1298    }
1299
1300    pub fn insert_excerpts_with_ids_after<O>(
1301        &mut self,
1302        prev_excerpt_id: ExcerptId,
1303        buffer: Model<Buffer>,
1304        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1305        cx: &mut ModelContext<Self>,
1306    ) where
1307        O: text::ToOffset,
1308    {
1309        assert_eq!(self.history.transaction_depth, 0);
1310        let mut ranges = ranges.into_iter().peekable();
1311        if ranges.peek().is_none() {
1312            return Default::default();
1313        }
1314
1315        self.sync(cx);
1316
1317        let buffer_id = buffer.read(cx).remote_id();
1318        let buffer_snapshot = buffer.read(cx).snapshot();
1319
1320        let mut buffers = self.buffers.borrow_mut();
1321        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
1322            last_version: buffer_snapshot.version().clone(),
1323            last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1324            excerpts: Default::default(),
1325            _subscriptions: [
1326                cx.observe(&buffer, |_, _, cx| cx.notify()),
1327                cx.subscribe(&buffer, Self::on_buffer_event),
1328            ],
1329            buffer: buffer.clone(),
1330        });
1331
1332        let mut snapshot = self.snapshot.borrow_mut();
1333
1334        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1335        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1336        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1337        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
1338        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1339
1340        let edit_start = new_excerpts.summary().text.len;
1341        new_excerpts.update_last(
1342            |excerpt| {
1343                excerpt.has_trailing_newline = true;
1344            },
1345            &(),
1346        );
1347
1348        let next_locator = if let Some(excerpt) = cursor.item() {
1349            excerpt.locator.clone()
1350        } else {
1351            Locator::max()
1352        };
1353
1354        let mut excerpts = Vec::new();
1355        while let Some((id, range)) = ranges.next() {
1356            let locator = Locator::between(&prev_locator, &next_locator);
1357            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1358                buffer_state.excerpts.insert(ix, locator.clone());
1359            }
1360            let range = ExcerptRange {
1361                context: buffer_snapshot.anchor_before(&range.context.start)
1362                    ..buffer_snapshot.anchor_after(&range.context.end),
1363                primary: range.primary.map(|primary| {
1364                    buffer_snapshot.anchor_before(&primary.start)
1365                        ..buffer_snapshot.anchor_after(&primary.end)
1366                }),
1367            };
1368            excerpts.push((id, range.clone()));
1369            let excerpt = Excerpt::new(
1370                id,
1371                locator.clone(),
1372                buffer_id,
1373                buffer_snapshot.clone(),
1374                range,
1375                ranges.peek().is_some() || cursor.item().is_some(),
1376            );
1377            new_excerpts.push(excerpt, &());
1378            prev_locator = locator.clone();
1379
1380            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1381                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1382            }
1383            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
1384        }
1385
1386        let edit_end = new_excerpts.summary().text.len;
1387
1388        let suffix = cursor.suffix(&());
1389        let changed_trailing_excerpt = suffix.is_empty();
1390        new_excerpts.append(suffix, &());
1391        drop(cursor);
1392        snapshot.excerpts = new_excerpts;
1393        snapshot.excerpt_ids = new_excerpt_ids;
1394        if changed_trailing_excerpt {
1395            snapshot.trailing_excerpt_update_count += 1;
1396        }
1397
1398        self.subscriptions.publish_mut([Edit {
1399            old: edit_start..edit_start,
1400            new: edit_start..edit_end,
1401        }]);
1402        cx.emit(Event::Edited {
1403            singleton_buffer_edited: false,
1404        });
1405        cx.emit(Event::ExcerptsAdded {
1406            buffer,
1407            predecessor: prev_excerpt_id,
1408            excerpts,
1409        });
1410        cx.notify();
1411    }
1412
1413    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1414        self.sync(cx);
1415        let ids = self.excerpt_ids();
1416        self.buffers.borrow_mut().clear();
1417        let mut snapshot = self.snapshot.borrow_mut();
1418        let prev_len = snapshot.len();
1419        snapshot.excerpts = Default::default();
1420        snapshot.trailing_excerpt_update_count += 1;
1421        snapshot.is_dirty = false;
1422        snapshot.has_conflict = false;
1423
1424        self.subscriptions.publish_mut([Edit {
1425            old: 0..prev_len,
1426            new: 0..0,
1427        }]);
1428        cx.emit(Event::Edited {
1429            singleton_buffer_edited: false,
1430        });
1431        cx.emit(Event::ExcerptsRemoved { ids });
1432        cx.notify();
1433    }
1434
1435    pub fn excerpts_for_buffer(
1436        &self,
1437        buffer: &Model<Buffer>,
1438        cx: &AppContext,
1439    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1440        let mut excerpts = Vec::new();
1441        let snapshot = self.read(cx);
1442        let buffers = self.buffers.borrow();
1443        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1444        for locator in buffers
1445            .get(&buffer.read(cx).remote_id())
1446            .map(|state| &state.excerpts)
1447            .into_iter()
1448            .flatten()
1449        {
1450            cursor.seek_forward(&Some(locator), Bias::Left, &());
1451            if let Some(excerpt) = cursor.item() {
1452                if excerpt.locator == *locator {
1453                    excerpts.push((excerpt.id, excerpt.range.clone()));
1454                }
1455            }
1456        }
1457
1458        excerpts
1459    }
1460
1461    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
1462        self.snapshot
1463            .borrow()
1464            .excerpts
1465            .iter()
1466            .map(|entry| entry.buffer_id)
1467            .collect()
1468    }
1469
1470    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1471        self.snapshot
1472            .borrow()
1473            .excerpts
1474            .iter()
1475            .map(|entry| entry.id)
1476            .collect()
1477    }
1478
1479    pub fn excerpt_containing(
1480        &self,
1481        position: impl ToOffset,
1482        cx: &AppContext,
1483    ) -> Option<(ExcerptId, Model<Buffer>, Range<text::Anchor>)> {
1484        let snapshot = self.read(cx);
1485        let position = position.to_offset(&snapshot);
1486
1487        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1488        cursor.seek(&position, Bias::Right, &());
1489        cursor
1490            .item()
1491            .or_else(|| snapshot.excerpts.last())
1492            .map(|excerpt| {
1493                (
1494                    excerpt.id,
1495                    self.buffers
1496                        .borrow()
1497                        .get(&excerpt.buffer_id)
1498                        .unwrap()
1499                        .buffer
1500                        .clone(),
1501                    excerpt.range.context.clone(),
1502                )
1503            })
1504    }
1505
1506    // If point is at the end of the buffer, the last excerpt is returned
1507    pub fn point_to_buffer_offset<T: ToOffset>(
1508        &self,
1509        point: T,
1510        cx: &AppContext,
1511    ) -> Option<(Model<Buffer>, usize, ExcerptId)> {
1512        let snapshot = self.read(cx);
1513        let offset = point.to_offset(&snapshot);
1514        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1515        cursor.seek(&offset, Bias::Right, &());
1516        if cursor.item().is_none() {
1517            cursor.prev(&());
1518        }
1519
1520        cursor.item().map(|excerpt| {
1521            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1522            let buffer_point = excerpt_start + offset - *cursor.start();
1523            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1524
1525            (buffer, buffer_point, excerpt.id)
1526        })
1527    }
1528
1529    // If point is at the end of the buffer, the last excerpt is returned
1530    pub fn point_to_buffer_point<T: ToPoint>(
1531        &self,
1532        point: T,
1533        cx: &AppContext,
1534    ) -> Option<(Model<Buffer>, Point, ExcerptId)> {
1535        let snapshot = self.read(cx);
1536        let point = point.to_point(&snapshot);
1537        let mut cursor = snapshot.excerpts.cursor::<Point>(&());
1538        cursor.seek(&point, Bias::Right, &());
1539        if cursor.item().is_none() {
1540            cursor.prev(&());
1541        }
1542
1543        cursor.item().map(|excerpt| {
1544            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
1545            let buffer_point = excerpt_start + point - *cursor.start();
1546            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1547
1548            (buffer, buffer_point, excerpt.id)
1549        })
1550    }
1551
1552    pub fn range_to_buffer_ranges<T: ToOffset>(
1553        &self,
1554        range: Range<T>,
1555        cx: &AppContext,
1556    ) -> Vec<(Model<Buffer>, Range<usize>, ExcerptId)> {
1557        let snapshot = self.read(cx);
1558        let start = range.start.to_offset(&snapshot);
1559        let end = range.end.to_offset(&snapshot);
1560
1561        let mut result = Vec::new();
1562        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1563        cursor.seek(&start, Bias::Right, &());
1564        if cursor.item().is_none() {
1565            cursor.prev(&());
1566        }
1567
1568        while let Some(excerpt) = cursor.item() {
1569            if *cursor.start() > end {
1570                break;
1571            }
1572
1573            let mut end_before_newline = cursor.end(&());
1574            if excerpt.has_trailing_newline {
1575                end_before_newline -= 1;
1576            }
1577            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1578            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1579            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1580            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1581            result.push((buffer, start..end, excerpt.id));
1582            cursor.next(&());
1583        }
1584
1585        result
1586    }
1587
1588    pub fn remove_excerpts(
1589        &mut self,
1590        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1591        cx: &mut ModelContext<Self>,
1592    ) {
1593        self.sync(cx);
1594        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1595        if ids.is_empty() {
1596            return;
1597        }
1598
1599        let mut buffers = self.buffers.borrow_mut();
1600        let mut snapshot = self.snapshot.borrow_mut();
1601        let mut new_excerpts = SumTree::default();
1602        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1603        let mut edits = Vec::new();
1604        let mut excerpt_ids = ids.iter().copied().peekable();
1605
1606        while let Some(excerpt_id) = excerpt_ids.next() {
1607            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1608            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1609            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1610
1611            if let Some(mut excerpt) = cursor.item() {
1612                if excerpt.id != excerpt_id {
1613                    continue;
1614                }
1615                let mut old_start = cursor.start().1;
1616
1617                // Skip over the removed excerpt.
1618                'remove_excerpts: loop {
1619                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1620                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1621                        if buffer_state.excerpts.is_empty() {
1622                            buffers.remove(&excerpt.buffer_id);
1623                        }
1624                    }
1625                    cursor.next(&());
1626
1627                    // Skip over any subsequent excerpts that are also removed.
1628                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
1629                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1630                        if let Some(next_excerpt) = cursor.item() {
1631                            if next_excerpt.locator == *next_locator {
1632                                excerpt_ids.next();
1633                                excerpt = next_excerpt;
1634                                continue 'remove_excerpts;
1635                            }
1636                        }
1637                    }
1638
1639                    break;
1640                }
1641
1642                // When removing the last excerpt, remove the trailing newline from
1643                // the previous excerpt.
1644                if cursor.item().is_none() && old_start > 0 {
1645                    old_start -= 1;
1646                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1647                }
1648
1649                // Push an edit for the removal of this run of excerpts.
1650                let old_end = cursor.start().1;
1651                let new_start = new_excerpts.summary().text.len;
1652                edits.push(Edit {
1653                    old: old_start..old_end,
1654                    new: new_start..new_start,
1655                });
1656            }
1657        }
1658        let suffix = cursor.suffix(&());
1659        let changed_trailing_excerpt = suffix.is_empty();
1660        new_excerpts.append(suffix, &());
1661        drop(cursor);
1662        snapshot.excerpts = new_excerpts;
1663
1664        if changed_trailing_excerpt {
1665            snapshot.trailing_excerpt_update_count += 1;
1666        }
1667
1668        self.subscriptions.publish_mut(edits);
1669        cx.emit(Event::Edited {
1670            singleton_buffer_edited: false,
1671        });
1672        cx.emit(Event::ExcerptsRemoved { ids });
1673        cx.notify();
1674    }
1675
1676    pub fn wait_for_anchors<'a>(
1677        &self,
1678        anchors: impl 'a + Iterator<Item = Anchor>,
1679        cx: &mut ModelContext<Self>,
1680    ) -> impl 'static + Future<Output = Result<()>> {
1681        let borrow = self.buffers.borrow();
1682        let mut error = None;
1683        let mut futures = Vec::new();
1684        for anchor in anchors {
1685            if let Some(buffer_id) = anchor.buffer_id {
1686                if let Some(buffer) = borrow.get(&buffer_id) {
1687                    buffer.buffer.update(cx, |buffer, _| {
1688                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1689                    });
1690                } else {
1691                    error = Some(anyhow!(
1692                        "buffer {buffer_id} is not part of this multi-buffer"
1693                    ));
1694                    break;
1695                }
1696            }
1697        }
1698        async move {
1699            if let Some(error) = error {
1700                Err(error)?;
1701            }
1702            for future in futures {
1703                future.await?;
1704            }
1705            Ok(())
1706        }
1707    }
1708
1709    pub fn text_anchor_for_position<T: ToOffset>(
1710        &self,
1711        position: T,
1712        cx: &AppContext,
1713    ) -> Option<(Model<Buffer>, language::Anchor)> {
1714        let snapshot = self.read(cx);
1715        let anchor = snapshot.anchor_before(position);
1716        let buffer = self
1717            .buffers
1718            .borrow()
1719            .get(&anchor.buffer_id?)?
1720            .buffer
1721            .clone();
1722        Some((buffer, anchor.text_anchor))
1723    }
1724
1725    fn on_buffer_event(
1726        &mut self,
1727        buffer: Model<Buffer>,
1728        event: &language::BufferEvent,
1729        cx: &mut ModelContext<Self>,
1730    ) {
1731        cx.emit(match event {
1732            language::BufferEvent::Edited => Event::Edited {
1733                singleton_buffer_edited: true,
1734            },
1735            language::BufferEvent::DirtyChanged => Event::DirtyChanged,
1736            language::BufferEvent::Saved => Event::Saved,
1737            language::BufferEvent::FileHandleChanged => Event::FileHandleChanged,
1738            language::BufferEvent::Reloaded => Event::Reloaded,
1739            language::BufferEvent::ReloadNeeded => Event::ReloadNeeded,
1740            language::BufferEvent::DiffBaseChanged => Event::DiffBaseChanged,
1741            language::BufferEvent::DiffUpdated => Event::DiffUpdated { buffer },
1742            language::BufferEvent::LanguageChanged => {
1743                Event::LanguageChanged(buffer.read(cx).remote_id())
1744            }
1745            language::BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
1746            language::BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1747            language::BufferEvent::Closed => Event::Closed,
1748            language::BufferEvent::Discarded => Event::Discarded,
1749            language::BufferEvent::CapabilityChanged => {
1750                self.capability = buffer.read(cx).capability();
1751                Event::CapabilityChanged
1752            }
1753            //
1754            language::BufferEvent::Operation { .. } => return,
1755        });
1756    }
1757
1758    pub fn all_buffers(&self) -> HashSet<Model<Buffer>> {
1759        self.buffers
1760            .borrow()
1761            .values()
1762            .map(|state| state.buffer.clone())
1763            .collect()
1764    }
1765
1766    pub fn buffer(&self, buffer_id: BufferId) -> Option<Model<Buffer>> {
1767        self.buffers
1768            .borrow()
1769            .get(&buffer_id)
1770            .map(|state| state.buffer.clone())
1771    }
1772
1773    pub fn language_at<T: ToOffset>(&self, point: T, cx: &AppContext) -> Option<Arc<Language>> {
1774        self.point_to_buffer_offset(point, cx)
1775            .and_then(|(buffer, offset, _)| buffer.read(cx).language_at(offset))
1776    }
1777
1778    pub fn settings_at<'a, T: ToOffset>(
1779        &self,
1780        point: T,
1781        cx: &'a AppContext,
1782    ) -> Cow<'a, LanguageSettings> {
1783        let mut language = None;
1784        let mut file = None;
1785        if let Some((buffer, offset, _)) = self.point_to_buffer_offset(point, cx) {
1786            let buffer = buffer.read(cx);
1787            language = buffer.language_at(offset);
1788            file = buffer.file();
1789        }
1790        language_settings(language.map(|l| l.name()), file, cx)
1791    }
1792
1793    pub fn for_each_buffer(&self, mut f: impl FnMut(&Model<Buffer>)) {
1794        self.buffers
1795            .borrow()
1796            .values()
1797            .for_each(|state| f(&state.buffer))
1798    }
1799
1800    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1801        if let Some(title) = self.title.as_ref() {
1802            return title.into();
1803        }
1804
1805        if let Some(buffer) = self.as_singleton() {
1806            if let Some(file) = buffer.read(cx).file() {
1807                return file.file_name(cx).to_string_lossy();
1808            }
1809        }
1810
1811        "untitled".into()
1812    }
1813
1814    pub fn set_title(&mut self, title: String, cx: &mut ModelContext<Self>) {
1815        self.title = Some(title);
1816        cx.notify();
1817    }
1818
1819    /// Preserve preview tabs containing this multibuffer until additional edits occur.
1820    pub fn refresh_preview(&self, cx: &mut ModelContext<Self>) {
1821        for buffer_state in self.buffers.borrow().values() {
1822            buffer_state
1823                .buffer
1824                .update(cx, |buffer, _cx| buffer.refresh_preview());
1825        }
1826    }
1827
1828    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
1829    pub fn preserve_preview(&self, cx: &AppContext) -> bool {
1830        self.buffers
1831            .borrow()
1832            .values()
1833            .all(|state| state.buffer.read(cx).preserve_preview())
1834    }
1835
1836    #[cfg(any(test, feature = "test-support"))]
1837    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1838        self.as_singleton().unwrap().read(cx).is_parsing()
1839    }
1840
1841    pub fn resize_excerpt(
1842        &mut self,
1843        id: ExcerptId,
1844        range: Range<text::Anchor>,
1845        cx: &mut ModelContext<Self>,
1846    ) {
1847        self.sync(cx);
1848
1849        let snapshot = self.snapshot(cx);
1850        let locator = snapshot.excerpt_locator_for_id(id);
1851        let mut new_excerpts = SumTree::default();
1852        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1853        let mut edits = Vec::<Edit<usize>>::new();
1854
1855        let prefix = cursor.slice(&Some(locator), Bias::Left, &());
1856        new_excerpts.append(prefix, &());
1857
1858        let mut excerpt = cursor.item().unwrap().clone();
1859        let old_text_len = excerpt.text_summary.len;
1860
1861        excerpt.range.context.start = range.start;
1862        excerpt.range.context.end = range.end;
1863        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
1864
1865        excerpt.text_summary = excerpt
1866            .buffer
1867            .text_summary_for_range(excerpt.range.context.clone());
1868
1869        let new_start_offset = new_excerpts.summary().text.len;
1870        let old_start_offset = cursor.start().1;
1871        let edit = Edit {
1872            old: old_start_offset..old_start_offset + old_text_len,
1873            new: new_start_offset..new_start_offset + excerpt.text_summary.len,
1874        };
1875
1876        if let Some(last_edit) = edits.last_mut() {
1877            if last_edit.old.end == edit.old.start {
1878                last_edit.old.end = edit.old.end;
1879                last_edit.new.end = edit.new.end;
1880            } else {
1881                edits.push(edit);
1882            }
1883        } else {
1884            edits.push(edit);
1885        }
1886
1887        new_excerpts.push(excerpt, &());
1888
1889        cursor.next(&());
1890
1891        new_excerpts.append(cursor.suffix(&()), &());
1892
1893        drop(cursor);
1894        self.snapshot.borrow_mut().excerpts = new_excerpts;
1895
1896        self.subscriptions.publish_mut(edits);
1897        cx.emit(Event::Edited {
1898            singleton_buffer_edited: false,
1899        });
1900        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
1901        cx.notify();
1902    }
1903
1904    pub fn expand_excerpts(
1905        &mut self,
1906        ids: impl IntoIterator<Item = ExcerptId>,
1907        line_count: u32,
1908        direction: ExpandExcerptDirection,
1909        cx: &mut ModelContext<Self>,
1910    ) {
1911        if line_count == 0 {
1912            return;
1913        }
1914        self.sync(cx);
1915
1916        let ids = ids.into_iter().collect::<Vec<_>>();
1917        let snapshot = self.snapshot(cx);
1918        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
1919        let mut new_excerpts = SumTree::default();
1920        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1921        let mut edits = Vec::<Edit<usize>>::new();
1922
1923        for locator in &locators {
1924            let prefix = cursor.slice(&Some(locator), Bias::Left, &());
1925            new_excerpts.append(prefix, &());
1926
1927            let mut excerpt = cursor.item().unwrap().clone();
1928            let old_text_len = excerpt.text_summary.len;
1929
1930            let up_line_count = if direction.should_expand_up() {
1931                line_count
1932            } else {
1933                0
1934            };
1935
1936            let start_row = excerpt
1937                .range
1938                .context
1939                .start
1940                .to_point(&excerpt.buffer)
1941                .row
1942                .saturating_sub(up_line_count);
1943            let start_point = Point::new(start_row, 0);
1944            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
1945
1946            let down_line_count = if direction.should_expand_down() {
1947                line_count
1948            } else {
1949                0
1950            };
1951
1952            let mut end_point = excerpt.buffer.clip_point(
1953                excerpt.range.context.end.to_point(&excerpt.buffer)
1954                    + Point::new(down_line_count, 0),
1955                Bias::Left,
1956            );
1957            end_point.column = excerpt.buffer.line_len(end_point.row);
1958            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
1959            excerpt.max_buffer_row = end_point.row;
1960
1961            excerpt.text_summary = excerpt
1962                .buffer
1963                .text_summary_for_range(excerpt.range.context.clone());
1964
1965            let new_start_offset = new_excerpts.summary().text.len;
1966            let old_start_offset = cursor.start().1;
1967            let edit = Edit {
1968                old: old_start_offset..old_start_offset + old_text_len,
1969                new: new_start_offset..new_start_offset + excerpt.text_summary.len,
1970            };
1971
1972            if let Some(last_edit) = edits.last_mut() {
1973                if last_edit.old.end == edit.old.start {
1974                    last_edit.old.end = edit.old.end;
1975                    last_edit.new.end = edit.new.end;
1976                } else {
1977                    edits.push(edit);
1978                }
1979            } else {
1980                edits.push(edit);
1981            }
1982
1983            new_excerpts.push(excerpt, &());
1984
1985            cursor.next(&());
1986        }
1987
1988        new_excerpts.append(cursor.suffix(&()), &());
1989
1990        drop(cursor);
1991        self.snapshot.borrow_mut().excerpts = new_excerpts;
1992
1993        self.subscriptions.publish_mut(edits);
1994        cx.emit(Event::Edited {
1995            singleton_buffer_edited: false,
1996        });
1997        cx.emit(Event::ExcerptsExpanded { ids });
1998        cx.notify();
1999    }
2000
2001    fn sync(&self, cx: &AppContext) {
2002        let mut snapshot = self.snapshot.borrow_mut();
2003        let mut excerpts_to_edit = Vec::new();
2004        let mut non_text_state_updated = false;
2005        let mut is_dirty = false;
2006        let mut has_conflict = false;
2007        let mut edited = false;
2008        let mut buffers = self.buffers.borrow_mut();
2009        for buffer_state in buffers.values_mut() {
2010            let buffer = buffer_state.buffer.read(cx);
2011            let version = buffer.version();
2012            let non_text_state_update_count = buffer.non_text_state_update_count();
2013
2014            let buffer_edited = version.changed_since(&buffer_state.last_version);
2015            let buffer_non_text_state_updated =
2016                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
2017            if buffer_edited || buffer_non_text_state_updated {
2018                buffer_state.last_version = version;
2019                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
2020                excerpts_to_edit.extend(
2021                    buffer_state
2022                        .excerpts
2023                        .iter()
2024                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
2025                );
2026            }
2027
2028            edited |= buffer_edited;
2029            non_text_state_updated |= buffer_non_text_state_updated;
2030            is_dirty |= buffer.is_dirty();
2031            has_conflict |= buffer.has_conflict();
2032        }
2033        if edited {
2034            snapshot.edit_count += 1;
2035        }
2036        if non_text_state_updated {
2037            snapshot.non_text_state_update_count += 1;
2038        }
2039        snapshot.is_dirty = is_dirty;
2040        snapshot.has_conflict = has_conflict;
2041
2042        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
2043
2044        let mut edits = Vec::new();
2045        let mut new_excerpts = SumTree::default();
2046        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
2047
2048        for (locator, buffer, buffer_edited) in excerpts_to_edit {
2049            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
2050            let old_excerpt = cursor.item().unwrap();
2051            let buffer = buffer.read(cx);
2052            let buffer_id = buffer.remote_id();
2053
2054            let mut new_excerpt;
2055            if buffer_edited {
2056                edits.extend(
2057                    buffer
2058                        .edits_since_in_range::<usize>(
2059                            old_excerpt.buffer.version(),
2060                            old_excerpt.range.context.clone(),
2061                        )
2062                        .map(|mut edit| {
2063                            let excerpt_old_start = cursor.start().1;
2064                            let excerpt_new_start = new_excerpts.summary().text.len;
2065                            edit.old.start += excerpt_old_start;
2066                            edit.old.end += excerpt_old_start;
2067                            edit.new.start += excerpt_new_start;
2068                            edit.new.end += excerpt_new_start;
2069                            edit
2070                        }),
2071                );
2072
2073                new_excerpt = Excerpt::new(
2074                    old_excerpt.id,
2075                    locator.clone(),
2076                    buffer_id,
2077                    buffer.snapshot(),
2078                    old_excerpt.range.clone(),
2079                    old_excerpt.has_trailing_newline,
2080                );
2081            } else {
2082                new_excerpt = old_excerpt.clone();
2083                new_excerpt.buffer = buffer.snapshot();
2084            }
2085
2086            new_excerpts.push(new_excerpt, &());
2087            cursor.next(&());
2088        }
2089        new_excerpts.append(cursor.suffix(&()), &());
2090
2091        drop(cursor);
2092        snapshot.excerpts = new_excerpts;
2093
2094        self.subscriptions.publish(edits);
2095    }
2096}
2097
2098#[cfg(any(test, feature = "test-support"))]
2099impl MultiBuffer {
2100    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> Model<Self> {
2101        let buffer = cx.new_model(|cx| Buffer::local(text, cx));
2102        cx.new_model(|cx| Self::singleton(buffer, cx))
2103    }
2104
2105    pub fn build_multi<const COUNT: usize>(
2106        excerpts: [(&str, Vec<Range<Point>>); COUNT],
2107        cx: &mut gpui::AppContext,
2108    ) -> Model<Self> {
2109        let multi = cx.new_model(|_| Self::new(Capability::ReadWrite));
2110        for (text, ranges) in excerpts {
2111            let buffer = cx.new_model(|cx| Buffer::local(text, cx));
2112            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
2113                context: range,
2114                primary: None,
2115            });
2116            multi.update(cx, |multi, cx| {
2117                multi.push_excerpts(buffer, excerpt_ranges, cx)
2118            });
2119        }
2120
2121        multi
2122    }
2123
2124    pub fn build_from_buffer(buffer: Model<Buffer>, cx: &mut gpui::AppContext) -> Model<Self> {
2125        cx.new_model(|cx| Self::singleton(buffer, cx))
2126    }
2127
2128    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> Model<Self> {
2129        cx.new_model(|cx| {
2130            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
2131            let mutation_count = rng.gen_range(1..=5);
2132            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
2133            multibuffer
2134        })
2135    }
2136
2137    pub fn randomly_edit(
2138        &mut self,
2139        rng: &mut impl rand::Rng,
2140        edit_count: usize,
2141        cx: &mut ModelContext<Self>,
2142    ) {
2143        use util::RandomCharIter;
2144
2145        let snapshot = self.read(cx);
2146        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
2147        let mut last_end = None;
2148        for _ in 0..edit_count {
2149            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
2150                break;
2151            }
2152
2153            let new_start = last_end.map_or(0, |last_end| last_end + 1);
2154            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
2155            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
2156            last_end = Some(end);
2157
2158            let mut range = start..end;
2159            if rng.gen_bool(0.2) {
2160                mem::swap(&mut range.start, &mut range.end);
2161            }
2162
2163            let new_text_len = rng.gen_range(0..10);
2164            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
2165
2166            edits.push((range, new_text.into()));
2167        }
2168        log::info!("mutating multi-buffer with {:?}", edits);
2169        drop(snapshot);
2170
2171        self.edit(edits, None, cx);
2172    }
2173
2174    pub fn randomly_edit_excerpts(
2175        &mut self,
2176        rng: &mut impl rand::Rng,
2177        mutation_count: usize,
2178        cx: &mut ModelContext<Self>,
2179    ) {
2180        use rand::prelude::*;
2181        use std::env;
2182        use util::RandomCharIter;
2183
2184        let max_excerpts = env::var("MAX_EXCERPTS")
2185            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
2186            .unwrap_or(5);
2187
2188        let mut buffers = Vec::new();
2189        for _ in 0..mutation_count {
2190            if rng.gen_bool(0.05) {
2191                log::info!("Clearing multi-buffer");
2192                self.clear(cx);
2193                continue;
2194            } else if rng.gen_bool(0.1) && !self.excerpt_ids().is_empty() {
2195                let ids = self.excerpt_ids();
2196                let mut excerpts = HashSet::default();
2197                for _ in 0..rng.gen_range(0..ids.len()) {
2198                    excerpts.extend(ids.choose(rng).copied());
2199                }
2200
2201                let line_count = rng.gen_range(0..5);
2202
2203                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
2204
2205                self.expand_excerpts(
2206                    excerpts.iter().cloned(),
2207                    line_count,
2208                    ExpandExcerptDirection::UpAndDown,
2209                    cx,
2210                );
2211                continue;
2212            }
2213
2214            let excerpt_ids = self.excerpt_ids();
2215            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
2216                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
2217                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
2218                    buffers.push(cx.new_model(|cx| Buffer::local(text, cx)));
2219                    let buffer = buffers.last().unwrap().read(cx);
2220                    log::info!(
2221                        "Creating new buffer {} with text: {:?}",
2222                        buffer.remote_id(),
2223                        buffer.text()
2224                    );
2225                    buffers.last().unwrap().clone()
2226                } else {
2227                    self.buffers
2228                        .borrow()
2229                        .values()
2230                        .choose(rng)
2231                        .unwrap()
2232                        .buffer
2233                        .clone()
2234                };
2235
2236                let buffer = buffer_handle.read(cx);
2237                let buffer_text = buffer.text();
2238                let ranges = (0..rng.gen_range(0..5))
2239                    .map(|_| {
2240                        let end_ix =
2241                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2242                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2243                        ExcerptRange {
2244                            context: start_ix..end_ix,
2245                            primary: None,
2246                        }
2247                    })
2248                    .collect::<Vec<_>>();
2249                log::info!(
2250                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
2251                    buffer_handle.read(cx).remote_id(),
2252                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
2253                    ranges
2254                        .iter()
2255                        .map(|r| &buffer_text[r.context.clone()])
2256                        .collect::<Vec<_>>()
2257                );
2258
2259                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
2260                log::info!("Inserted with ids: {:?}", excerpt_id);
2261            } else {
2262                let remove_count = rng.gen_range(1..=excerpt_ids.len());
2263                let mut excerpts_to_remove = excerpt_ids
2264                    .choose_multiple(rng, remove_count)
2265                    .cloned()
2266                    .collect::<Vec<_>>();
2267                let snapshot = self.snapshot.borrow();
2268                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
2269                drop(snapshot);
2270                log::info!("Removing excerpts {:?}", excerpts_to_remove);
2271                self.remove_excerpts(excerpts_to_remove, cx);
2272            }
2273        }
2274    }
2275
2276    pub fn randomly_mutate(
2277        &mut self,
2278        rng: &mut impl rand::Rng,
2279        mutation_count: usize,
2280        cx: &mut ModelContext<Self>,
2281    ) {
2282        use rand::prelude::*;
2283
2284        if rng.gen_bool(0.7) || self.singleton {
2285            let buffer = self
2286                .buffers
2287                .borrow()
2288                .values()
2289                .choose(rng)
2290                .map(|state| state.buffer.clone());
2291
2292            if let Some(buffer) = buffer {
2293                buffer.update(cx, |buffer, cx| {
2294                    if rng.gen() {
2295                        buffer.randomly_edit(rng, mutation_count, cx);
2296                    } else {
2297                        buffer.randomly_undo_redo(rng, cx);
2298                    }
2299                });
2300            } else {
2301                self.randomly_edit(rng, mutation_count, cx);
2302            }
2303        } else {
2304            self.randomly_edit_excerpts(rng, mutation_count, cx);
2305        }
2306
2307        self.check_invariants(cx);
2308    }
2309
2310    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
2311        let snapshot = self.read(cx);
2312        let excerpts = snapshot.excerpts.items(&());
2313        let excerpt_ids = snapshot.excerpt_ids.items(&());
2314
2315        for (ix, excerpt) in excerpts.iter().enumerate() {
2316            if ix == 0 {
2317                if excerpt.locator <= Locator::min() {
2318                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
2319                }
2320            } else if excerpt.locator <= excerpts[ix - 1].locator {
2321                panic!("excerpts are out-of-order: {:?}", excerpts);
2322            }
2323        }
2324
2325        for (ix, entry) in excerpt_ids.iter().enumerate() {
2326            if ix == 0 {
2327                if entry.id.cmp(&ExcerptId::min(), &snapshot).is_le() {
2328                    panic!("invalid first excerpt id {:?}", entry.id);
2329                }
2330            } else if entry.id <= excerpt_ids[ix - 1].id {
2331                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
2332            }
2333        }
2334    }
2335}
2336
2337impl EventEmitter<Event> for MultiBuffer {}
2338
2339impl MultiBufferSnapshot {
2340    pub fn text(&self) -> String {
2341        self.chunks(0..self.len(), false)
2342            .map(|chunk| chunk.text)
2343            .collect()
2344    }
2345
2346    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2347        let mut offset = position.to_offset(self);
2348        let mut cursor = self.excerpts.cursor::<usize>(&());
2349        cursor.seek(&offset, Bias::Left, &());
2350        let mut excerpt_chunks = cursor.item().map(|excerpt| {
2351            let end_before_footer = cursor.start() + excerpt.text_summary.len;
2352            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2353            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
2354            excerpt.buffer.reversed_chunks_in_range(start..end)
2355        });
2356        iter::from_fn(move || {
2357            if offset == *cursor.start() {
2358                cursor.prev(&());
2359                let excerpt = cursor.item()?;
2360                excerpt_chunks = Some(
2361                    excerpt
2362                        .buffer
2363                        .reversed_chunks_in_range(excerpt.range.context.clone()),
2364                );
2365            }
2366
2367            let excerpt = cursor.item().unwrap();
2368            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
2369                offset -= 1;
2370                Some("\n")
2371            } else {
2372                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
2373                offset -= chunk.len();
2374                Some(chunk)
2375            }
2376        })
2377        .flat_map(|c| c.chars().rev())
2378    }
2379
2380    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2381        let offset = position.to_offset(self);
2382        self.text_for_range(offset..self.len())
2383            .flat_map(|chunk| chunk.chars())
2384    }
2385
2386    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
2387        self.chunks(range, false).map(|chunk| chunk.text)
2388    }
2389
2390    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
2391        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
2392            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
2393    }
2394
2395    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
2396    where
2397        T: ToOffset,
2398    {
2399        let position = position.to_offset(self);
2400        position == self.clip_offset(position, Bias::Left)
2401            && self
2402                .bytes_in_range(position..self.len())
2403                .flatten()
2404                .copied()
2405                .take(needle.len())
2406                .eq(needle.bytes())
2407    }
2408
2409    pub fn surrounding_word<T: ToOffset>(
2410        &self,
2411        start: T,
2412        for_completion: bool,
2413    ) -> (Range<usize>, Option<CharKind>) {
2414        let mut start = start.to_offset(self);
2415        let mut end = start;
2416        let mut next_chars = self.chars_at(start).peekable();
2417        let mut prev_chars = self.reversed_chars_at(start).peekable();
2418
2419        let classifier = self
2420            .char_classifier_at(start)
2421            .for_completion(for_completion);
2422
2423        let word_kind = cmp::max(
2424            prev_chars.peek().copied().map(|c| classifier.kind(c)),
2425            next_chars.peek().copied().map(|c| classifier.kind(c)),
2426        );
2427
2428        for ch in prev_chars {
2429            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
2430                start -= ch.len_utf8();
2431            } else {
2432                break;
2433            }
2434        }
2435
2436        for ch in next_chars {
2437            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
2438                end += ch.len_utf8();
2439            } else {
2440                break;
2441            }
2442        }
2443
2444        (start..end, word_kind)
2445    }
2446
2447    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
2448        if self.singleton {
2449            self.excerpts
2450                .iter()
2451                .next()
2452                .map(|e| (&e.id, e.buffer_id, &e.buffer))
2453        } else {
2454            None
2455        }
2456    }
2457
2458    pub fn len(&self) -> usize {
2459        self.excerpts.summary().text.len
2460    }
2461
2462    pub fn is_empty(&self) -> bool {
2463        self.excerpts.summary().text.len == 0
2464    }
2465
2466    pub fn max_buffer_row(&self) -> MultiBufferRow {
2467        self.excerpts.summary().max_buffer_row
2468    }
2469
2470    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2471        if let Some((_, _, buffer)) = self.as_singleton() {
2472            return buffer.clip_offset(offset, bias);
2473        }
2474
2475        let mut cursor = self.excerpts.cursor::<usize>(&());
2476        cursor.seek(&offset, Bias::Right, &());
2477        let overshoot = if let Some(excerpt) = cursor.item() {
2478            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2479            let buffer_offset = excerpt
2480                .buffer
2481                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
2482            buffer_offset.saturating_sub(excerpt_start)
2483        } else {
2484            0
2485        };
2486        cursor.start() + overshoot
2487    }
2488
2489    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2490        if let Some((_, _, buffer)) = self.as_singleton() {
2491            return buffer.clip_point(point, bias);
2492        }
2493
2494        let mut cursor = self.excerpts.cursor::<Point>(&());
2495        cursor.seek(&point, Bias::Right, &());
2496        let overshoot = if let Some(excerpt) = cursor.item() {
2497            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2498            let buffer_point = excerpt
2499                .buffer
2500                .clip_point(excerpt_start + (point - cursor.start()), bias);
2501            buffer_point.saturating_sub(excerpt_start)
2502        } else {
2503            Point::zero()
2504        };
2505        *cursor.start() + overshoot
2506    }
2507
2508    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2509        if let Some((_, _, buffer)) = self.as_singleton() {
2510            return buffer.clip_offset_utf16(offset, bias);
2511        }
2512
2513        let mut cursor = self.excerpts.cursor::<OffsetUtf16>(&());
2514        cursor.seek(&offset, Bias::Right, &());
2515        let overshoot = if let Some(excerpt) = cursor.item() {
2516            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2517            let buffer_offset = excerpt
2518                .buffer
2519                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
2520            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
2521        } else {
2522            OffsetUtf16(0)
2523        };
2524        *cursor.start() + overshoot
2525    }
2526
2527    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2528        if let Some((_, _, buffer)) = self.as_singleton() {
2529            return buffer.clip_point_utf16(point, bias);
2530        }
2531
2532        let mut cursor = self.excerpts.cursor::<PointUtf16>(&());
2533        cursor.seek(&point.0, Bias::Right, &());
2534        let overshoot = if let Some(excerpt) = cursor.item() {
2535            let excerpt_start = excerpt
2536                .buffer
2537                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2538            let buffer_point = excerpt
2539                .buffer
2540                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
2541            buffer_point.saturating_sub(excerpt_start)
2542        } else {
2543            PointUtf16::zero()
2544        };
2545        *cursor.start() + overshoot
2546    }
2547
2548    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
2549        let range = range.start.to_offset(self)..range.end.to_offset(self);
2550        let mut excerpts = self.excerpts.cursor::<usize>(&());
2551        excerpts.seek(&range.start, Bias::Right, &());
2552
2553        let mut chunk = &[][..];
2554        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2555            let mut excerpt_bytes = excerpt
2556                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
2557            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2558            Some(excerpt_bytes)
2559        } else {
2560            None
2561        };
2562        MultiBufferBytes {
2563            range,
2564            excerpts,
2565            excerpt_bytes,
2566            chunk,
2567        }
2568    }
2569
2570    pub fn reversed_bytes_in_range<T: ToOffset>(
2571        &self,
2572        range: Range<T>,
2573    ) -> ReversedMultiBufferBytes {
2574        let range = range.start.to_offset(self)..range.end.to_offset(self);
2575        let mut excerpts = self.excerpts.cursor::<usize>(&());
2576        excerpts.seek(&range.end, Bias::Left, &());
2577
2578        let mut chunk = &[][..];
2579        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2580            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
2581                range.start.saturating_sub(*excerpts.start())..range.end - *excerpts.start(),
2582            );
2583            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2584            Some(excerpt_bytes)
2585        } else {
2586            None
2587        };
2588
2589        ReversedMultiBufferBytes {
2590            range,
2591            excerpts,
2592            excerpt_bytes,
2593            chunk,
2594        }
2595    }
2596
2597    pub fn buffer_rows(&self, start_row: MultiBufferRow) -> MultiBufferRows {
2598        let mut result = MultiBufferRows {
2599            buffer_row_range: 0..0,
2600            excerpts: self.excerpts.cursor(&()),
2601        };
2602        result.seek(start_row);
2603        result
2604    }
2605
2606    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
2607        let range = range.start.to_offset(self)..range.end.to_offset(self);
2608        let mut chunks = MultiBufferChunks {
2609            range: range.clone(),
2610            excerpts: self.excerpts.cursor(&()),
2611            excerpt_chunks: None,
2612            language_aware,
2613        };
2614        chunks.seek(range);
2615        chunks
2616    }
2617
2618    pub fn offset_to_point(&self, offset: usize) -> Point {
2619        if let Some((_, _, buffer)) = self.as_singleton() {
2620            return buffer.offset_to_point(offset);
2621        }
2622
2623        let mut cursor = self.excerpts.cursor::<(usize, Point)>(&());
2624        cursor.seek(&offset, Bias::Right, &());
2625        if let Some(excerpt) = cursor.item() {
2626            let (start_offset, start_point) = cursor.start();
2627            let overshoot = offset - start_offset;
2628            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2629            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2630            let buffer_point = excerpt
2631                .buffer
2632                .offset_to_point(excerpt_start_offset + overshoot);
2633            *start_point + (buffer_point - excerpt_start_point)
2634        } else {
2635            self.excerpts.summary().text.lines
2636        }
2637    }
2638
2639    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2640        if let Some((_, _, buffer)) = self.as_singleton() {
2641            return buffer.offset_to_point_utf16(offset);
2642        }
2643
2644        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>(&());
2645        cursor.seek(&offset, Bias::Right, &());
2646        if let Some(excerpt) = cursor.item() {
2647            let (start_offset, start_point) = cursor.start();
2648            let overshoot = offset - start_offset;
2649            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2650            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2651            let buffer_point = excerpt
2652                .buffer
2653                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2654            *start_point + (buffer_point - excerpt_start_point)
2655        } else {
2656            self.excerpts.summary().text.lines_utf16()
2657        }
2658    }
2659
2660    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2661        if let Some((_, _, buffer)) = self.as_singleton() {
2662            return buffer.point_to_point_utf16(point);
2663        }
2664
2665        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>(&());
2666        cursor.seek(&point, Bias::Right, &());
2667        if let Some(excerpt) = cursor.item() {
2668            let (start_offset, start_point) = cursor.start();
2669            let overshoot = point - start_offset;
2670            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2671            let excerpt_start_point_utf16 =
2672                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2673            let buffer_point = excerpt
2674                .buffer
2675                .point_to_point_utf16(excerpt_start_point + overshoot);
2676            *start_point + (buffer_point - excerpt_start_point_utf16)
2677        } else {
2678            self.excerpts.summary().text.lines_utf16()
2679        }
2680    }
2681
2682    pub fn point_to_offset(&self, point: Point) -> usize {
2683        if let Some((_, _, buffer)) = self.as_singleton() {
2684            return buffer.point_to_offset(point);
2685        }
2686
2687        let mut cursor = self.excerpts.cursor::<(Point, usize)>(&());
2688        cursor.seek(&point, Bias::Right, &());
2689        if let Some(excerpt) = cursor.item() {
2690            let (start_point, start_offset) = cursor.start();
2691            let overshoot = point - start_point;
2692            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2693            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2694            let buffer_offset = excerpt
2695                .buffer
2696                .point_to_offset(excerpt_start_point + overshoot);
2697            *start_offset + buffer_offset - excerpt_start_offset
2698        } else {
2699            self.excerpts.summary().text.len
2700        }
2701    }
2702
2703    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2704        if let Some((_, _, buffer)) = self.as_singleton() {
2705            return buffer.offset_utf16_to_offset(offset_utf16);
2706        }
2707
2708        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>(&());
2709        cursor.seek(&offset_utf16, Bias::Right, &());
2710        if let Some(excerpt) = cursor.item() {
2711            let (start_offset_utf16, start_offset) = cursor.start();
2712            let overshoot = offset_utf16 - start_offset_utf16;
2713            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2714            let excerpt_start_offset_utf16 =
2715                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2716            let buffer_offset = excerpt
2717                .buffer
2718                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2719            *start_offset + (buffer_offset - excerpt_start_offset)
2720        } else {
2721            self.excerpts.summary().text.len
2722        }
2723    }
2724
2725    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2726        if let Some((_, _, buffer)) = self.as_singleton() {
2727            return buffer.offset_to_offset_utf16(offset);
2728        }
2729
2730        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>(&());
2731        cursor.seek(&offset, Bias::Right, &());
2732        if let Some(excerpt) = cursor.item() {
2733            let (start_offset, start_offset_utf16) = cursor.start();
2734            let overshoot = offset - start_offset;
2735            let excerpt_start_offset_utf16 =
2736                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2737            let excerpt_start_offset = excerpt
2738                .buffer
2739                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2740            let buffer_offset_utf16 = excerpt
2741                .buffer
2742                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2743            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2744        } else {
2745            self.excerpts.summary().text.len_utf16
2746        }
2747    }
2748
2749    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2750        if let Some((_, _, buffer)) = self.as_singleton() {
2751            return buffer.point_utf16_to_offset(point);
2752        }
2753
2754        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>(&());
2755        cursor.seek(&point, Bias::Right, &());
2756        if let Some(excerpt) = cursor.item() {
2757            let (start_point, start_offset) = cursor.start();
2758            let overshoot = point - start_point;
2759            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2760            let excerpt_start_point = excerpt
2761                .buffer
2762                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2763            let buffer_offset = excerpt
2764                .buffer
2765                .point_utf16_to_offset(excerpt_start_point + overshoot);
2766            *start_offset + (buffer_offset - excerpt_start_offset)
2767        } else {
2768            self.excerpts.summary().text.len
2769        }
2770    }
2771
2772    pub fn point_to_buffer_offset<T: ToOffset>(
2773        &self,
2774        point: T,
2775    ) -> Option<(&BufferSnapshot, usize)> {
2776        let offset = point.to_offset(self);
2777        let mut cursor = self.excerpts.cursor::<usize>(&());
2778        cursor.seek(&offset, Bias::Right, &());
2779        if cursor.item().is_none() {
2780            cursor.prev(&());
2781        }
2782
2783        cursor.item().map(|excerpt| {
2784            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2785            let buffer_point = excerpt_start + offset - *cursor.start();
2786            (&excerpt.buffer, buffer_point)
2787        })
2788    }
2789
2790    pub fn suggested_indents(
2791        &self,
2792        rows: impl IntoIterator<Item = u32>,
2793        cx: &AppContext,
2794    ) -> BTreeMap<MultiBufferRow, IndentSize> {
2795        let mut result = BTreeMap::new();
2796
2797        let mut rows_for_excerpt = Vec::new();
2798        let mut cursor = self.excerpts.cursor::<Point>(&());
2799        let mut rows = rows.into_iter().peekable();
2800        let mut prev_row = u32::MAX;
2801        let mut prev_language_indent_size = IndentSize::default();
2802
2803        while let Some(row) = rows.next() {
2804            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2805            let excerpt = match cursor.item() {
2806                Some(excerpt) => excerpt,
2807                _ => continue,
2808            };
2809
2810            // Retrieve the language and indent size once for each disjoint region being indented.
2811            let single_indent_size = if row.saturating_sub(1) == prev_row {
2812                prev_language_indent_size
2813            } else {
2814                excerpt
2815                    .buffer
2816                    .language_indent_size_at(Point::new(row, 0), cx)
2817            };
2818            prev_language_indent_size = single_indent_size;
2819            prev_row = row;
2820
2821            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2822            let start_multibuffer_row = cursor.start().row;
2823
2824            rows_for_excerpt.push(row);
2825            while let Some(next_row) = rows.peek().copied() {
2826                if cursor.end(&()).row > next_row {
2827                    rows_for_excerpt.push(next_row);
2828                    rows.next();
2829                } else {
2830                    break;
2831                }
2832            }
2833
2834            let buffer_rows = rows_for_excerpt
2835                .drain(..)
2836                .map(|row| start_buffer_row + row - start_multibuffer_row);
2837            let buffer_indents = excerpt
2838                .buffer
2839                .suggested_indents(buffer_rows, single_indent_size);
2840            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
2841                (
2842                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
2843                    indent,
2844                )
2845            });
2846            result.extend(multibuffer_indents);
2847        }
2848
2849        result
2850    }
2851
2852    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
2853        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2854            let mut size = buffer.indent_size_for_line(range.start.row);
2855            size.len = size
2856                .len
2857                .min(range.end.column)
2858                .saturating_sub(range.start.column);
2859            size
2860        } else {
2861            IndentSize::spaces(0)
2862        }
2863    }
2864
2865    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
2866        while row.0 > 0 {
2867            row.0 -= 1;
2868            if !self.is_line_blank(row) {
2869                return Some(row);
2870            }
2871        }
2872        None
2873    }
2874
2875    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
2876        if let Some((_, range)) = self.buffer_line_for_row(row) {
2877            range.end.column - range.start.column
2878        } else {
2879            0
2880        }
2881    }
2882
2883    pub fn buffer_line_for_row(
2884        &self,
2885        row: MultiBufferRow,
2886    ) -> Option<(&BufferSnapshot, Range<Point>)> {
2887        let mut cursor = self.excerpts.cursor::<Point>(&());
2888        let point = Point::new(row.0, 0);
2889        cursor.seek(&point, Bias::Right, &());
2890        if cursor.item().is_none() && *cursor.start() == point {
2891            cursor.prev(&());
2892        }
2893        if let Some(excerpt) = cursor.item() {
2894            let overshoot = row.0 - cursor.start().row;
2895            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2896            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2897            let buffer_row = excerpt_start.row + overshoot;
2898            let line_start = Point::new(buffer_row, 0);
2899            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2900            return Some((
2901                &excerpt.buffer,
2902                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2903            ));
2904        }
2905        None
2906    }
2907
2908    pub fn max_point(&self) -> Point {
2909        self.text_summary().lines
2910    }
2911
2912    pub fn text_summary(&self) -> TextSummary {
2913        self.excerpts.summary().text.clone()
2914    }
2915
2916    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2917    where
2918        D: TextDimension,
2919        O: ToOffset,
2920    {
2921        let mut summary = D::zero(&());
2922        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2923        let mut cursor = self.excerpts.cursor::<usize>(&());
2924        cursor.seek(&range.start, Bias::Right, &());
2925        if let Some(excerpt) = cursor.item() {
2926            let mut end_before_newline = cursor.end(&());
2927            if excerpt.has_trailing_newline {
2928                end_before_newline -= 1;
2929            }
2930
2931            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2932            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2933            let end_in_excerpt =
2934                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2935            summary.add_assign(
2936                &excerpt
2937                    .buffer
2938                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2939            );
2940
2941            if range.end > end_before_newline {
2942                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2943            }
2944
2945            cursor.next(&());
2946        }
2947
2948        if range.end > *cursor.start() {
2949            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2950                &range.end,
2951                Bias::Right,
2952                &(),
2953            )));
2954            if let Some(excerpt) = cursor.item() {
2955                range.end = cmp::max(*cursor.start(), range.end);
2956
2957                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2958                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2959                summary.add_assign(
2960                    &excerpt
2961                        .buffer
2962                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2963                );
2964            }
2965        }
2966
2967        summary
2968    }
2969
2970    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2971    where
2972        D: TextDimension + Ord + Sub<D, Output = D>,
2973    {
2974        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
2975        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
2976
2977        cursor.seek(locator, Bias::Left, &());
2978        if cursor.item().is_none() {
2979            cursor.next(&());
2980        }
2981
2982        let mut position = D::from_text_summary(&cursor.start().text);
2983        if let Some(excerpt) = cursor.item() {
2984            if excerpt.id == anchor.excerpt_id {
2985                let excerpt_buffer_start =
2986                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2987                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2988                let buffer_position = cmp::min(
2989                    excerpt_buffer_end,
2990                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
2991                );
2992                if buffer_position > excerpt_buffer_start {
2993                    position.add_assign(&(buffer_position - excerpt_buffer_start));
2994                }
2995            }
2996        }
2997        position
2998    }
2999
3000    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
3001    where
3002        D: TextDimension + Ord + Sub<D, Output = D>,
3003        I: 'a + IntoIterator<Item = &'a Anchor>,
3004    {
3005        if let Some((_, _, buffer)) = self.as_singleton() {
3006            return buffer
3007                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
3008                .collect();
3009        }
3010
3011        let mut anchors = anchors.into_iter().peekable();
3012        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
3013        let mut summaries = Vec::new();
3014        while let Some(anchor) = anchors.peek() {
3015            let excerpt_id = anchor.excerpt_id;
3016            let excerpt_anchors = iter::from_fn(|| {
3017                let anchor = anchors.peek()?;
3018                if anchor.excerpt_id == excerpt_id {
3019                    Some(&anchors.next().unwrap().text_anchor)
3020                } else {
3021                    None
3022                }
3023            });
3024
3025            let locator = self.excerpt_locator_for_id(excerpt_id);
3026            cursor.seek_forward(locator, Bias::Left, &());
3027            if cursor.item().is_none() {
3028                cursor.next(&());
3029            }
3030
3031            let position = D::from_text_summary(&cursor.start().text);
3032            if let Some(excerpt) = cursor.item() {
3033                if excerpt.id == excerpt_id {
3034                    let excerpt_buffer_start =
3035                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
3036                    let excerpt_buffer_end =
3037                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
3038                    summaries.extend(
3039                        excerpt
3040                            .buffer
3041                            .summaries_for_anchors::<D, _>(excerpt_anchors)
3042                            .map(move |summary| {
3043                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
3044                                let mut position = position.clone();
3045                                let excerpt_buffer_start = excerpt_buffer_start.clone();
3046                                if summary > excerpt_buffer_start {
3047                                    position.add_assign(&(summary - excerpt_buffer_start));
3048                                }
3049                                position
3050                            }),
3051                    );
3052                    continue;
3053                }
3054            }
3055
3056            summaries.extend(excerpt_anchors.map(|_| position.clone()));
3057        }
3058
3059        summaries
3060    }
3061
3062    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
3063    where
3064        I: 'a + IntoIterator<Item = &'a Anchor>,
3065    {
3066        let mut anchors = anchors.into_iter().enumerate().peekable();
3067        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3068        cursor.next(&());
3069
3070        let mut result = Vec::new();
3071
3072        while let Some((_, anchor)) = anchors.peek() {
3073            let old_excerpt_id = anchor.excerpt_id;
3074
3075            // Find the location where this anchor's excerpt should be.
3076            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
3077            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
3078
3079            if cursor.item().is_none() {
3080                cursor.next(&());
3081            }
3082
3083            let next_excerpt = cursor.item();
3084            let prev_excerpt = cursor.prev_item();
3085
3086            // Process all of the anchors for this excerpt.
3087            while let Some((_, anchor)) = anchors.peek() {
3088                if anchor.excerpt_id != old_excerpt_id {
3089                    break;
3090                }
3091                let (anchor_ix, anchor) = anchors.next().unwrap();
3092                let mut anchor = *anchor;
3093
3094                // Leave min and max anchors unchanged if invalid or
3095                // if the old excerpt still exists at this location
3096                let mut kept_position = next_excerpt
3097                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
3098                    || old_excerpt_id == ExcerptId::max()
3099                    || old_excerpt_id == ExcerptId::min();
3100
3101                // If the old excerpt no longer exists at this location, then attempt to
3102                // find an equivalent position for this anchor in an adjacent excerpt.
3103                if !kept_position {
3104                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
3105                        if excerpt.contains(&anchor) {
3106                            anchor.excerpt_id = excerpt.id;
3107                            kept_position = true;
3108                            break;
3109                        }
3110                    }
3111                }
3112
3113                // If there's no adjacent excerpt that contains the anchor's position,
3114                // then report that the anchor has lost its position.
3115                if !kept_position {
3116                    anchor = if let Some(excerpt) = next_excerpt {
3117                        let mut text_anchor = excerpt
3118                            .range
3119                            .context
3120                            .start
3121                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
3122                        if text_anchor
3123                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
3124                            .is_gt()
3125                        {
3126                            text_anchor = excerpt.range.context.end;
3127                        }
3128                        Anchor {
3129                            buffer_id: Some(excerpt.buffer_id),
3130                            excerpt_id: excerpt.id,
3131                            text_anchor,
3132                        }
3133                    } else if let Some(excerpt) = prev_excerpt {
3134                        let mut text_anchor = excerpt
3135                            .range
3136                            .context
3137                            .end
3138                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
3139                        if text_anchor
3140                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
3141                            .is_lt()
3142                        {
3143                            text_anchor = excerpt.range.context.start;
3144                        }
3145                        Anchor {
3146                            buffer_id: Some(excerpt.buffer_id),
3147                            excerpt_id: excerpt.id,
3148                            text_anchor,
3149                        }
3150                    } else if anchor.text_anchor.bias == Bias::Left {
3151                        Anchor::min()
3152                    } else {
3153                        Anchor::max()
3154                    };
3155                }
3156
3157                result.push((anchor_ix, anchor, kept_position));
3158            }
3159        }
3160        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
3161        result
3162    }
3163
3164    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
3165        self.anchor_at(position, Bias::Left)
3166    }
3167
3168    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
3169        self.anchor_at(position, Bias::Right)
3170    }
3171
3172    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
3173        let offset = position.to_offset(self);
3174        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
3175            return Anchor {
3176                buffer_id: Some(buffer_id),
3177                excerpt_id: *excerpt_id,
3178                text_anchor: buffer.anchor_at(offset, bias),
3179            };
3180        }
3181
3182        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>(&());
3183        cursor.seek(&offset, Bias::Right, &());
3184        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
3185            cursor.prev(&());
3186        }
3187        if let Some(excerpt) = cursor.item() {
3188            let mut overshoot = offset.saturating_sub(cursor.start().0);
3189            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
3190                overshoot -= 1;
3191                bias = Bias::Right;
3192            }
3193
3194            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3195            let text_anchor =
3196                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
3197            Anchor {
3198                buffer_id: Some(excerpt.buffer_id),
3199                excerpt_id: excerpt.id,
3200                text_anchor,
3201            }
3202        } else if offset == 0 && bias == Bias::Left {
3203            Anchor::min()
3204        } else {
3205            Anchor::max()
3206        }
3207    }
3208
3209    /// Returns an anchor for the given excerpt and text anchor,
3210    /// returns None if the excerpt_id is no longer valid.
3211    pub fn anchor_in_excerpt(
3212        &self,
3213        excerpt_id: ExcerptId,
3214        text_anchor: text::Anchor,
3215    ) -> Option<Anchor> {
3216        let locator = self.excerpt_locator_for_id(excerpt_id);
3217        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3218        cursor.seek(locator, Bias::Left, &());
3219        if let Some(excerpt) = cursor.item() {
3220            if excerpt.id == excerpt_id {
3221                let text_anchor = excerpt.clip_anchor(text_anchor);
3222                drop(cursor);
3223                return Some(Anchor {
3224                    buffer_id: Some(excerpt.buffer_id),
3225                    excerpt_id,
3226                    text_anchor,
3227                });
3228            }
3229        }
3230        None
3231    }
3232
3233    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
3234        Some(self.excerpt(excerpt_id)?.range.context.clone())
3235    }
3236
3237    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
3238        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
3239            true
3240        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
3241            excerpt.buffer.can_resolve(&anchor.text_anchor)
3242        } else {
3243            false
3244        }
3245    }
3246
3247    pub fn excerpts(
3248        &self,
3249    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
3250        self.excerpts
3251            .iter()
3252            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
3253    }
3254
3255    fn excerpts_for_range<T: ToOffset>(
3256        &self,
3257        range: Range<T>,
3258    ) -> impl Iterator<Item = (&Excerpt, usize)> + '_ {
3259        let range = range.start.to_offset(self)..range.end.to_offset(self);
3260
3261        let mut cursor = self.excerpts.cursor::<usize>(&());
3262        cursor.seek(&range.start, Bias::Right, &());
3263        cursor.prev(&());
3264
3265        iter::from_fn(move || {
3266            cursor.next(&());
3267            if cursor.start() < &range.end {
3268                cursor.item().map(|item| (item, *cursor.start()))
3269            } else {
3270                None
3271            }
3272        })
3273    }
3274
3275    pub fn excerpt_boundaries_in_range<R, T>(
3276        &self,
3277        range: R,
3278    ) -> impl Iterator<Item = ExcerptBoundary> + '_
3279    where
3280        R: RangeBounds<T>,
3281        T: ToOffset,
3282    {
3283        let start_offset;
3284        let start = match range.start_bound() {
3285            Bound::Included(start) => {
3286                start_offset = start.to_offset(self);
3287                Bound::Included(start_offset)
3288            }
3289            Bound::Excluded(start) => {
3290                start_offset = start.to_offset(self);
3291                Bound::Excluded(start_offset)
3292            }
3293            Bound::Unbounded => {
3294                start_offset = 0;
3295                Bound::Unbounded
3296            }
3297        };
3298        let end = match range.end_bound() {
3299            Bound::Included(end) => Bound::Included(end.to_offset(self)),
3300            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
3301            Bound::Unbounded => Bound::Unbounded,
3302        };
3303        let bounds = (start, end);
3304
3305        let mut cursor = self.excerpts.cursor::<(usize, Point)>(&());
3306        cursor.seek(&start_offset, Bias::Right, &());
3307        if cursor.item().is_none() {
3308            cursor.prev(&());
3309        }
3310        if !bounds.contains(&cursor.start().0) {
3311            cursor.next(&());
3312        }
3313
3314        let mut visited_end = false;
3315        std::iter::from_fn(move || {
3316            if self.singleton {
3317                None
3318            } else if bounds.contains(&cursor.start().0) {
3319                let next = cursor.item().map(|excerpt| ExcerptInfo {
3320                    id: excerpt.id,
3321                    buffer: excerpt.buffer.clone(),
3322                    buffer_id: excerpt.buffer_id,
3323                    range: excerpt.range.clone(),
3324                });
3325
3326                if next.is_none() {
3327                    if visited_end {
3328                        return None;
3329                    } else {
3330                        visited_end = true;
3331                    }
3332                }
3333
3334                let prev = cursor.prev_item().map(|prev_excerpt| ExcerptInfo {
3335                    id: prev_excerpt.id,
3336                    buffer: prev_excerpt.buffer.clone(),
3337                    buffer_id: prev_excerpt.buffer_id,
3338                    range: prev_excerpt.range.clone(),
3339                });
3340                let row = MultiBufferRow(cursor.start().1.row);
3341
3342                cursor.next(&());
3343
3344                Some(ExcerptBoundary { row, prev, next })
3345            } else {
3346                None
3347            }
3348        })
3349    }
3350
3351    pub fn edit_count(&self) -> usize {
3352        self.edit_count
3353    }
3354
3355    pub fn non_text_state_update_count(&self) -> usize {
3356        self.non_text_state_update_count
3357    }
3358
3359    /// Returns the smallest enclosing bracket ranges containing the given range or
3360    /// None if no brackets contain range or the range is not contained in a single
3361    /// excerpt
3362    ///
3363    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
3364    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
3365        &self,
3366        range: Range<T>,
3367        range_filter: Option<&dyn Fn(Range<usize>, Range<usize>) -> bool>,
3368    ) -> Option<(Range<usize>, Range<usize>)> {
3369        let range = range.start.to_offset(self)..range.end.to_offset(self);
3370        let excerpt = self.excerpt_containing(range.clone())?;
3371
3372        // Filter to ranges contained in the excerpt
3373        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
3374            excerpt.contains_buffer_range(open.start..close.end)
3375                && range_filter.map_or(true, |filter| {
3376                    filter(
3377                        excerpt.map_range_from_buffer(open),
3378                        excerpt.map_range_from_buffer(close),
3379                    )
3380                })
3381        };
3382
3383        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
3384            excerpt.map_range_to_buffer(range),
3385            Some(&range_filter),
3386        )?;
3387
3388        Some((
3389            excerpt.map_range_from_buffer(open),
3390            excerpt.map_range_from_buffer(close),
3391        ))
3392    }
3393
3394    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
3395    /// not contained in a single excerpt
3396    pub fn enclosing_bracket_ranges<T: ToOffset>(
3397        &self,
3398        range: Range<T>,
3399    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3400        let range = range.start.to_offset(self)..range.end.to_offset(self);
3401        let excerpt = self.excerpt_containing(range.clone())?;
3402
3403        Some(
3404            excerpt
3405                .buffer()
3406                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
3407                .filter_map(move |(open, close)| {
3408                    if excerpt.contains_buffer_range(open.start..close.end) {
3409                        Some((
3410                            excerpt.map_range_from_buffer(open),
3411                            excerpt.map_range_from_buffer(close),
3412                        ))
3413                    } else {
3414                        None
3415                    }
3416                }),
3417        )
3418    }
3419
3420    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
3421    /// not contained in a single excerpt
3422    pub fn bracket_ranges<T: ToOffset>(
3423        &self,
3424        range: Range<T>,
3425    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3426        let range = range.start.to_offset(self)..range.end.to_offset(self);
3427        let excerpt = self.excerpt_containing(range.clone())?;
3428
3429        Some(
3430            excerpt
3431                .buffer()
3432                .bracket_ranges(excerpt.map_range_to_buffer(range))
3433                .filter_map(move |(start_bracket_range, close_bracket_range)| {
3434                    let buffer_range = start_bracket_range.start..close_bracket_range.end;
3435                    if excerpt.contains_buffer_range(buffer_range) {
3436                        Some((
3437                            excerpt.map_range_from_buffer(start_bracket_range),
3438                            excerpt.map_range_from_buffer(close_bracket_range),
3439                        ))
3440                    } else {
3441                        None
3442                    }
3443                }),
3444        )
3445    }
3446
3447    pub fn redacted_ranges<'a, T: ToOffset>(
3448        &'a self,
3449        range: Range<T>,
3450        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
3451    ) -> impl Iterator<Item = Range<usize>> + 'a {
3452        let range = range.start.to_offset(self)..range.end.to_offset(self);
3453        self.excerpts_for_range(range.clone())
3454            .filter(move |&(excerpt, _)| redaction_enabled(excerpt.buffer.file()))
3455            .flat_map(move |(excerpt, excerpt_offset)| {
3456                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3457
3458                excerpt
3459                    .buffer
3460                    .redacted_ranges(excerpt.range.context.clone())
3461                    .map(move |mut redacted_range| {
3462                        // Re-base onto the excerpts coordinates in the multibuffer
3463                        redacted_range.start = excerpt_offset
3464                            + redacted_range.start.saturating_sub(excerpt_buffer_start);
3465                        redacted_range.end = excerpt_offset
3466                            + redacted_range.end.saturating_sub(excerpt_buffer_start);
3467
3468                        redacted_range
3469                    })
3470                    .skip_while(move |redacted_range| redacted_range.end < range.start)
3471                    .take_while(move |redacted_range| redacted_range.start < range.end)
3472            })
3473    }
3474
3475    pub fn runnable_ranges(
3476        &self,
3477        range: Range<Anchor>,
3478    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
3479        let range = range.start.to_offset(self)..range.end.to_offset(self);
3480        self.excerpts_for_range(range.clone())
3481            .flat_map(move |(excerpt, excerpt_offset)| {
3482                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3483
3484                excerpt
3485                    .buffer
3486                    .runnable_ranges(excerpt.range.context.clone())
3487                    .filter_map(move |mut runnable| {
3488                        // Re-base onto the excerpts coordinates in the multibuffer
3489                        //
3490                        // The node matching our runnables query might partially overlap with
3491                        // the provided range. If the run indicator is outside of excerpt bounds, do not actually show it.
3492                        if runnable.run_range.start < excerpt_buffer_start {
3493                            return None;
3494                        }
3495                        if language::ToPoint::to_point(&runnable.run_range.end, &excerpt.buffer).row
3496                            > excerpt.max_buffer_row
3497                        {
3498                            return None;
3499                        }
3500                        runnable.run_range.start =
3501                            excerpt_offset + runnable.run_range.start - excerpt_buffer_start;
3502                        runnable.run_range.end =
3503                            excerpt_offset + runnable.run_range.end - excerpt_buffer_start;
3504                        Some(runnable)
3505                    })
3506                    .skip_while(move |runnable| runnable.run_range.end < range.start)
3507                    .take_while(move |runnable| runnable.run_range.start < range.end)
3508            })
3509    }
3510
3511    pub fn indent_guides_in_range(
3512        &self,
3513        range: Range<Anchor>,
3514        ignore_disabled_for_language: bool,
3515        cx: &AppContext,
3516    ) -> Vec<MultiBufferIndentGuide> {
3517        // Fast path for singleton buffers, we can skip the conversion between offsets.
3518        if let Some((_, _, snapshot)) = self.as_singleton() {
3519            return snapshot
3520                .indent_guides_in_range(
3521                    range.start.text_anchor..range.end.text_anchor,
3522                    ignore_disabled_for_language,
3523                    cx,
3524                )
3525                .into_iter()
3526                .map(|guide| MultiBufferIndentGuide {
3527                    multibuffer_row_range: MultiBufferRow(guide.start_row)
3528                        ..MultiBufferRow(guide.end_row),
3529                    buffer: guide,
3530                })
3531                .collect();
3532        }
3533
3534        let range = range.start.to_offset(self)..range.end.to_offset(self);
3535
3536        self.excerpts_for_range(range.clone())
3537            .flat_map(move |(excerpt, excerpt_offset)| {
3538                let excerpt_buffer_start_row =
3539                    excerpt.range.context.start.to_point(&excerpt.buffer).row;
3540                let excerpt_offset_row = crate::ToPoint::to_point(&excerpt_offset, self).row;
3541
3542                excerpt
3543                    .buffer
3544                    .indent_guides_in_range(
3545                        excerpt.range.context.clone(),
3546                        ignore_disabled_for_language,
3547                        cx,
3548                    )
3549                    .into_iter()
3550                    .map(move |indent_guide| {
3551                        let start_row = excerpt_offset_row
3552                            + (indent_guide.start_row - excerpt_buffer_start_row);
3553                        let end_row =
3554                            excerpt_offset_row + (indent_guide.end_row - excerpt_buffer_start_row);
3555
3556                        MultiBufferIndentGuide {
3557                            multibuffer_row_range: MultiBufferRow(start_row)
3558                                ..MultiBufferRow(end_row),
3559                            buffer: indent_guide,
3560                        }
3561                    })
3562            })
3563            .collect()
3564    }
3565
3566    pub fn trailing_excerpt_update_count(&self) -> usize {
3567        self.trailing_excerpt_update_count
3568    }
3569
3570    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
3571        self.point_to_buffer_offset(point)
3572            .and_then(|(buffer, _)| buffer.file())
3573    }
3574
3575    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
3576        self.point_to_buffer_offset(point)
3577            .and_then(|(buffer, offset)| buffer.language_at(offset))
3578    }
3579
3580    pub fn settings_at<'a, T: ToOffset>(
3581        &'a self,
3582        point: T,
3583        cx: &'a AppContext,
3584    ) -> Cow<'a, LanguageSettings> {
3585        let mut language = None;
3586        let mut file = None;
3587        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
3588            language = buffer.language_at(offset);
3589            file = buffer.file();
3590        }
3591        language_settings(language.map(|l| l.name()), file, cx)
3592    }
3593
3594    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
3595        self.point_to_buffer_offset(point)
3596            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
3597    }
3598
3599    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
3600        self.point_to_buffer_offset(point)
3601            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
3602            .unwrap_or_default()
3603    }
3604
3605    pub fn language_indent_size_at<T: ToOffset>(
3606        &self,
3607        position: T,
3608        cx: &AppContext,
3609    ) -> Option<IndentSize> {
3610        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
3611        Some(buffer_snapshot.language_indent_size_at(offset, cx))
3612    }
3613
3614    pub fn is_dirty(&self) -> bool {
3615        self.is_dirty
3616    }
3617
3618    pub fn has_conflict(&self) -> bool {
3619        self.has_conflict
3620    }
3621
3622    pub fn has_diagnostics(&self) -> bool {
3623        self.excerpts
3624            .iter()
3625            .any(|excerpt| excerpt.buffer.has_diagnostics())
3626    }
3627
3628    pub fn diagnostic_group<'a, O>(
3629        &'a self,
3630        group_id: usize,
3631    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3632    where
3633        O: text::FromAnchor + 'a,
3634    {
3635        self.as_singleton()
3636            .into_iter()
3637            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
3638    }
3639
3640    pub fn diagnostics_in_range<'a, T, O>(
3641        &'a self,
3642        range: Range<T>,
3643        reversed: bool,
3644    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3645    where
3646        T: 'a + ToOffset,
3647        O: 'a + text::FromAnchor + Ord,
3648    {
3649        self.as_singleton()
3650            .into_iter()
3651            .flat_map(move |(_, _, buffer)| {
3652                buffer.diagnostics_in_range(
3653                    range.start.to_offset(self)..range.end.to_offset(self),
3654                    reversed,
3655                )
3656            })
3657    }
3658
3659    pub fn has_git_diffs(&self) -> bool {
3660        for excerpt in self.excerpts.iter() {
3661            if excerpt.buffer.has_git_diff() {
3662                return true;
3663            }
3664        }
3665        false
3666    }
3667
3668    pub fn git_diff_hunks_in_range_rev(
3669        &self,
3670        row_range: Range<MultiBufferRow>,
3671    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3672        let mut cursor = self.excerpts.cursor::<Point>(&());
3673
3674        cursor.seek(&Point::new(row_range.end.0, 0), Bias::Left, &());
3675        if cursor.item().is_none() {
3676            cursor.prev(&());
3677        }
3678
3679        std::iter::from_fn(move || {
3680            let excerpt = cursor.item()?;
3681            let multibuffer_start = *cursor.start();
3682            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3683            if multibuffer_start.row >= row_range.end.0 {
3684                return None;
3685            }
3686
3687            let mut buffer_start = excerpt.range.context.start;
3688            let mut buffer_end = excerpt.range.context.end;
3689            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3690            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3691
3692            if row_range.start.0 > multibuffer_start.row {
3693                let buffer_start_point =
3694                    excerpt_start_point + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3695                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3696            }
3697
3698            if row_range.end.0 < multibuffer_end.row {
3699                let buffer_end_point =
3700                    excerpt_start_point + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3701                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3702            }
3703
3704            let buffer_hunks = excerpt
3705                .buffer
3706                .git_diff_hunks_intersecting_range_rev(buffer_start..buffer_end)
3707                .map(move |hunk| {
3708                    let start = multibuffer_start.row
3709                        + hunk.row_range.start.saturating_sub(excerpt_start_point.row);
3710                    let end = multibuffer_start.row
3711                        + hunk
3712                            .row_range
3713                            .end
3714                            .min(excerpt_end_point.row + 1)
3715                            .saturating_sub(excerpt_start_point.row);
3716
3717                    MultiBufferDiffHunk {
3718                        row_range: MultiBufferRow(start)..MultiBufferRow(end),
3719                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3720                        buffer_range: hunk.buffer_range.clone(),
3721                        buffer_id: excerpt.buffer_id,
3722                    }
3723                });
3724
3725            cursor.prev(&());
3726
3727            Some(buffer_hunks)
3728        })
3729        .flatten()
3730    }
3731
3732    pub fn git_diff_hunks_in_range(
3733        &self,
3734        row_range: Range<MultiBufferRow>,
3735    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3736        let mut cursor = self.excerpts.cursor::<Point>(&());
3737
3738        cursor.seek(&Point::new(row_range.start.0, 0), Bias::Left, &());
3739
3740        std::iter::from_fn(move || {
3741            let excerpt = cursor.item()?;
3742            let multibuffer_start = *cursor.start();
3743            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3744            let mut buffer_start = excerpt.range.context.start;
3745            let mut buffer_end = excerpt.range.context.end;
3746
3747            let excerpt_rows = match multibuffer_start.row.cmp(&row_range.end.0) {
3748                cmp::Ordering::Less => {
3749                    let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3750                    let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3751
3752                    if row_range.start.0 > multibuffer_start.row {
3753                        let buffer_start_point = excerpt_start_point
3754                            + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3755                        buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3756                    }
3757
3758                    if row_range.end.0 < multibuffer_end.row {
3759                        let buffer_end_point = excerpt_start_point
3760                            + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3761                        buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3762                    }
3763                    excerpt_start_point.row..excerpt_end_point.row
3764                }
3765                cmp::Ordering::Equal if row_range.end.0 == 0 => {
3766                    buffer_end = buffer_start;
3767                    0..0
3768                }
3769                cmp::Ordering::Greater | cmp::Ordering::Equal => return None,
3770            };
3771
3772            let buffer_hunks = excerpt
3773                .buffer
3774                .git_diff_hunks_intersecting_range(buffer_start..buffer_end)
3775                .map(move |hunk| {
3776                    let buffer_range = if excerpt_rows.start == 0 && excerpt_rows.end == 0 {
3777                        MultiBufferRow(0)..MultiBufferRow(1)
3778                    } else {
3779                        let start = multibuffer_start.row
3780                            + hunk.row_range.start.saturating_sub(excerpt_rows.start);
3781                        let end = multibuffer_start.row
3782                            + hunk
3783                                .row_range
3784                                .end
3785                                .min(excerpt_rows.end + 1)
3786                                .saturating_sub(excerpt_rows.start);
3787                        MultiBufferRow(start)..MultiBufferRow(end)
3788                    };
3789                    MultiBufferDiffHunk {
3790                        row_range: buffer_range,
3791                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3792                        buffer_range: hunk.buffer_range.clone(),
3793                        buffer_id: excerpt.buffer_id,
3794                    }
3795                });
3796
3797            cursor.next(&());
3798
3799            Some(buffer_hunks)
3800        })
3801        .flatten()
3802    }
3803
3804    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
3805        let range = range.start.to_offset(self)..range.end.to_offset(self);
3806        let excerpt = self.excerpt_containing(range.clone())?;
3807
3808        let ancestor_buffer_range = excerpt
3809            .buffer()
3810            .range_for_syntax_ancestor(excerpt.map_range_to_buffer(range))?;
3811
3812        Some(excerpt.map_range_from_buffer(ancestor_buffer_range))
3813    }
3814
3815    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
3816        let (excerpt_id, _, buffer) = self.as_singleton()?;
3817        let outline = buffer.outline(theme)?;
3818        Some(Outline::new(
3819            outline
3820                .items
3821                .into_iter()
3822                .flat_map(|item| {
3823                    Some(OutlineItem {
3824                        depth: item.depth,
3825                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
3826                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
3827                        text: item.text,
3828                        highlight_ranges: item.highlight_ranges,
3829                        name_ranges: item.name_ranges,
3830                        body_range: item.body_range.and_then(|body_range| {
3831                            Some(
3832                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
3833                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
3834                            )
3835                        }),
3836                        annotation_range: item.annotation_range.and_then(|annotation_range| {
3837                            Some(
3838                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
3839                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
3840                            )
3841                        }),
3842                    })
3843                })
3844                .collect(),
3845        ))
3846    }
3847
3848    pub fn symbols_containing<T: ToOffset>(
3849        &self,
3850        offset: T,
3851        theme: Option<&SyntaxTheme>,
3852    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
3853        let anchor = self.anchor_before(offset);
3854        let excerpt_id = anchor.excerpt_id;
3855        let excerpt = self.excerpt(excerpt_id)?;
3856        Some((
3857            excerpt.buffer_id,
3858            excerpt
3859                .buffer
3860                .symbols_containing(anchor.text_anchor, theme)
3861                .into_iter()
3862                .flatten()
3863                .flat_map(|item| {
3864                    Some(OutlineItem {
3865                        depth: item.depth,
3866                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
3867                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
3868                        text: item.text,
3869                        highlight_ranges: item.highlight_ranges,
3870                        name_ranges: item.name_ranges,
3871                        body_range: item.body_range.and_then(|body_range| {
3872                            Some(
3873                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
3874                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
3875                            )
3876                        }),
3877                        annotation_range: item.annotation_range.and_then(|body_range| {
3878                            Some(
3879                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
3880                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
3881                            )
3882                        }),
3883                    })
3884                })
3885                .collect(),
3886        ))
3887    }
3888
3889    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
3890        if id == ExcerptId::min() {
3891            Locator::min_ref()
3892        } else if id == ExcerptId::max() {
3893            Locator::max_ref()
3894        } else {
3895            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
3896            cursor.seek(&id, Bias::Left, &());
3897            if let Some(entry) = cursor.item() {
3898                if entry.id == id {
3899                    return &entry.locator;
3900                }
3901            }
3902            panic!("invalid excerpt id {:?}", id)
3903        }
3904    }
3905
3906    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
3907    fn excerpt_locators_for_ids(
3908        &self,
3909        ids: impl IntoIterator<Item = ExcerptId>,
3910    ) -> SmallVec<[Locator; 1]> {
3911        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
3912        sorted_ids.sort_unstable();
3913        let mut locators = SmallVec::new();
3914
3915        while sorted_ids.last() == Some(&ExcerptId::max()) {
3916            sorted_ids.pop();
3917            if let Some(mapping) = self.excerpt_ids.last() {
3918                locators.push(mapping.locator.clone());
3919            }
3920        }
3921
3922        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
3923        if sorted_ids.peek() == Some(&ExcerptId::min()) {
3924            sorted_ids.next();
3925            if let Some(mapping) = self.excerpt_ids.first() {
3926                locators.push(mapping.locator.clone());
3927            }
3928        }
3929
3930        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
3931        for id in sorted_ids {
3932            if cursor.seek_forward(&id, Bias::Left, &()) {
3933                locators.push(cursor.item().unwrap().locator.clone());
3934            } else {
3935                panic!("invalid excerpt id {:?}", id);
3936            }
3937        }
3938
3939        locators.sort_unstable();
3940        locators
3941    }
3942
3943    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
3944        Some(self.excerpt(excerpt_id)?.buffer_id)
3945    }
3946
3947    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
3948        Some(&self.excerpt(excerpt_id)?.buffer)
3949    }
3950
3951    pub fn range_for_excerpt<'a, T: sum_tree::Dimension<'a, ExcerptSummary>>(
3952        &'a self,
3953        excerpt_id: ExcerptId,
3954    ) -> Option<Range<T>> {
3955        let mut cursor = self.excerpts.cursor::<(Option<&Locator>, T)>(&());
3956        let locator = self.excerpt_locator_for_id(excerpt_id);
3957        if cursor.seek(&Some(locator), Bias::Left, &()) {
3958            let start = cursor.start().1.clone();
3959            let end = cursor.end(&()).1;
3960            Some(start..end)
3961        } else {
3962            None
3963        }
3964    }
3965
3966    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
3967        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3968        let locator = self.excerpt_locator_for_id(excerpt_id);
3969        cursor.seek(&Some(locator), Bias::Left, &());
3970        if let Some(excerpt) = cursor.item() {
3971            if excerpt.id == excerpt_id {
3972                return Some(excerpt);
3973            }
3974        }
3975        None
3976    }
3977
3978    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
3979    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
3980        let range = range.start.to_offset(self)..range.end.to_offset(self);
3981
3982        let mut cursor = self.excerpts.cursor::<usize>(&());
3983        cursor.seek(&range.start, Bias::Right, &());
3984        let start_excerpt = cursor.item()?;
3985
3986        if range.start == range.end {
3987            return Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()));
3988        }
3989
3990        cursor.seek(&range.end, Bias::Right, &());
3991        let end_excerpt = cursor.item()?;
3992
3993        if start_excerpt.id == end_excerpt.id {
3994            Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()))
3995        } else {
3996            None
3997        }
3998    }
3999
4000    // Takes an iterator over anchor ranges and returns a new iterator over anchor ranges that don't
4001    // span across excerpt boundaries.
4002    pub fn split_ranges<'a, I>(&'a self, ranges: I) -> impl Iterator<Item = Range<Anchor>> + 'a
4003    where
4004        I: IntoIterator<Item = Range<Anchor>> + 'a,
4005    {
4006        let mut ranges = ranges.into_iter().map(|range| range.to_offset(self));
4007        let mut cursor = self.excerpts.cursor::<usize>(&());
4008        cursor.next(&());
4009        let mut current_range = ranges.next();
4010        iter::from_fn(move || {
4011            let range = current_range.clone()?;
4012            if range.start >= cursor.end(&()) {
4013                cursor.seek_forward(&range.start, Bias::Right, &());
4014                if range.start == self.len() {
4015                    cursor.prev(&());
4016                }
4017            }
4018
4019            let excerpt = cursor.item()?;
4020            let range_start_in_excerpt = cmp::max(range.start, *cursor.start());
4021            let range_end_in_excerpt = if excerpt.has_trailing_newline {
4022                cmp::min(range.end, cursor.end(&()) - 1)
4023            } else {
4024                cmp::min(range.end, cursor.end(&()))
4025            };
4026            let buffer_range = MultiBufferExcerpt::new(excerpt, *cursor.start())
4027                .map_range_to_buffer(range_start_in_excerpt..range_end_in_excerpt);
4028
4029            let subrange_start_anchor = Anchor {
4030                buffer_id: Some(excerpt.buffer_id),
4031                excerpt_id: excerpt.id,
4032                text_anchor: excerpt.buffer.anchor_before(buffer_range.start),
4033            };
4034            let subrange_end_anchor = Anchor {
4035                buffer_id: Some(excerpt.buffer_id),
4036                excerpt_id: excerpt.id,
4037                text_anchor: excerpt.buffer.anchor_after(buffer_range.end),
4038            };
4039
4040            if range.end > cursor.end(&()) {
4041                cursor.next(&());
4042            } else {
4043                current_range = ranges.next();
4044            }
4045
4046            Some(subrange_start_anchor..subrange_end_anchor)
4047        })
4048    }
4049
4050    /// Returns excerpts overlapping the given ranges. If range spans multiple excerpts returns one range for each excerpt
4051    ///
4052    /// The ranges are specified in the coordinate space of the multibuffer, not the individual excerpted buffers.
4053    /// Each returned excerpt's range is in the coordinate space of its source buffer.
4054    pub fn excerpts_in_ranges(
4055        &self,
4056        ranges: impl IntoIterator<Item = Range<Anchor>>,
4057    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, Range<usize>)> {
4058        let mut ranges = ranges.into_iter().map(|range| range.to_offset(self));
4059        let mut cursor = self.excerpts.cursor::<usize>(&());
4060        cursor.next(&());
4061        let mut current_range = ranges.next();
4062        iter::from_fn(move || {
4063            let range = current_range.clone()?;
4064            if range.start >= cursor.end(&()) {
4065                cursor.seek_forward(&range.start, Bias::Right, &());
4066                if range.start == self.len() {
4067                    cursor.prev(&());
4068                }
4069            }
4070
4071            let excerpt = cursor.item()?;
4072            let range_start_in_excerpt = cmp::max(range.start, *cursor.start());
4073            let range_end_in_excerpt = if excerpt.has_trailing_newline {
4074                cmp::min(range.end, cursor.end(&()) - 1)
4075            } else {
4076                cmp::min(range.end, cursor.end(&()))
4077            };
4078            let buffer_range = MultiBufferExcerpt::new(excerpt, *cursor.start())
4079                .map_range_to_buffer(range_start_in_excerpt..range_end_in_excerpt);
4080
4081            if range.end > cursor.end(&()) {
4082                cursor.next(&());
4083            } else {
4084                current_range = ranges.next();
4085            }
4086
4087            Some((excerpt.id, &excerpt.buffer, buffer_range))
4088        })
4089    }
4090
4091    pub fn selections_in_range<'a>(
4092        &'a self,
4093        range: &'a Range<Anchor>,
4094        include_local: bool,
4095    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
4096        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
4097        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
4098        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
4099        cursor.seek(start_locator, Bias::Left, &());
4100        cursor
4101            .take_while(move |excerpt| excerpt.locator <= *end_locator)
4102            .flat_map(move |excerpt| {
4103                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
4104                if excerpt.id == range.start.excerpt_id {
4105                    query_range.start = range.start.text_anchor;
4106                }
4107                if excerpt.id == range.end.excerpt_id {
4108                    query_range.end = range.end.text_anchor;
4109                }
4110
4111                excerpt
4112                    .buffer
4113                    .selections_in_range(query_range, include_local)
4114                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
4115                        selections.map(move |selection| {
4116                            let mut start = Anchor {
4117                                buffer_id: Some(excerpt.buffer_id),
4118                                excerpt_id: excerpt.id,
4119                                text_anchor: selection.start,
4120                            };
4121                            let mut end = Anchor {
4122                                buffer_id: Some(excerpt.buffer_id),
4123                                excerpt_id: excerpt.id,
4124                                text_anchor: selection.end,
4125                            };
4126                            if range.start.cmp(&start, self).is_gt() {
4127                                start = range.start;
4128                            }
4129                            if range.end.cmp(&end, self).is_lt() {
4130                                end = range.end;
4131                            }
4132
4133                            (
4134                                replica_id,
4135                                line_mode,
4136                                cursor_shape,
4137                                Selection {
4138                                    id: selection.id,
4139                                    start,
4140                                    end,
4141                                    reversed: selection.reversed,
4142                                    goal: selection.goal,
4143                                },
4144                            )
4145                        })
4146                    })
4147            })
4148    }
4149
4150    pub fn show_headers(&self) -> bool {
4151        self.show_headers
4152    }
4153}
4154
4155#[cfg(any(test, feature = "test-support"))]
4156impl MultiBufferSnapshot {
4157    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
4158        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
4159        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
4160        start..end
4161    }
4162}
4163
4164impl History {
4165    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
4166        self.transaction_depth += 1;
4167        if self.transaction_depth == 1 {
4168            let id = self.next_transaction_id.tick();
4169            self.undo_stack.push(Transaction {
4170                id,
4171                buffer_transactions: Default::default(),
4172                first_edit_at: now,
4173                last_edit_at: now,
4174                suppress_grouping: false,
4175            });
4176            Some(id)
4177        } else {
4178            None
4179        }
4180    }
4181
4182    fn end_transaction(
4183        &mut self,
4184        now: Instant,
4185        buffer_transactions: HashMap<BufferId, TransactionId>,
4186    ) -> bool {
4187        assert_ne!(self.transaction_depth, 0);
4188        self.transaction_depth -= 1;
4189        if self.transaction_depth == 0 {
4190            if buffer_transactions.is_empty() {
4191                self.undo_stack.pop();
4192                false
4193            } else {
4194                self.redo_stack.clear();
4195                let transaction = self.undo_stack.last_mut().unwrap();
4196                transaction.last_edit_at = now;
4197                for (buffer_id, transaction_id) in buffer_transactions {
4198                    transaction
4199                        .buffer_transactions
4200                        .entry(buffer_id)
4201                        .or_insert(transaction_id);
4202                }
4203                true
4204            }
4205        } else {
4206            false
4207        }
4208    }
4209
4210    fn push_transaction<'a, T>(
4211        &mut self,
4212        buffer_transactions: T,
4213        now: Instant,
4214        cx: &ModelContext<MultiBuffer>,
4215    ) where
4216        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
4217    {
4218        assert_eq!(self.transaction_depth, 0);
4219        let transaction = Transaction {
4220            id: self.next_transaction_id.tick(),
4221            buffer_transactions: buffer_transactions
4222                .into_iter()
4223                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
4224                .collect(),
4225            first_edit_at: now,
4226            last_edit_at: now,
4227            suppress_grouping: false,
4228        };
4229        if !transaction.buffer_transactions.is_empty() {
4230            self.undo_stack.push(transaction);
4231            self.redo_stack.clear();
4232        }
4233    }
4234
4235    fn finalize_last_transaction(&mut self) {
4236        if let Some(transaction) = self.undo_stack.last_mut() {
4237            transaction.suppress_grouping = true;
4238        }
4239    }
4240
4241    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
4242        if let Some(ix) = self
4243            .undo_stack
4244            .iter()
4245            .rposition(|transaction| transaction.id == transaction_id)
4246        {
4247            Some(self.undo_stack.remove(ix))
4248        } else if let Some(ix) = self
4249            .redo_stack
4250            .iter()
4251            .rposition(|transaction| transaction.id == transaction_id)
4252        {
4253            Some(self.redo_stack.remove(ix))
4254        } else {
4255            None
4256        }
4257    }
4258
4259    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
4260        self.undo_stack
4261            .iter()
4262            .find(|transaction| transaction.id == transaction_id)
4263            .or_else(|| {
4264                self.redo_stack
4265                    .iter()
4266                    .find(|transaction| transaction.id == transaction_id)
4267            })
4268    }
4269
4270    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
4271        self.undo_stack
4272            .iter_mut()
4273            .find(|transaction| transaction.id == transaction_id)
4274            .or_else(|| {
4275                self.redo_stack
4276                    .iter_mut()
4277                    .find(|transaction| transaction.id == transaction_id)
4278            })
4279    }
4280
4281    fn pop_undo(&mut self) -> Option<&mut Transaction> {
4282        assert_eq!(self.transaction_depth, 0);
4283        if let Some(transaction) = self.undo_stack.pop() {
4284            self.redo_stack.push(transaction);
4285            self.redo_stack.last_mut()
4286        } else {
4287            None
4288        }
4289    }
4290
4291    fn pop_redo(&mut self) -> Option<&mut Transaction> {
4292        assert_eq!(self.transaction_depth, 0);
4293        if let Some(transaction) = self.redo_stack.pop() {
4294            self.undo_stack.push(transaction);
4295            self.undo_stack.last_mut()
4296        } else {
4297            None
4298        }
4299    }
4300
4301    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
4302        let ix = self
4303            .undo_stack
4304            .iter()
4305            .rposition(|transaction| transaction.id == transaction_id)?;
4306        let transaction = self.undo_stack.remove(ix);
4307        self.redo_stack.push(transaction);
4308        self.redo_stack.last()
4309    }
4310
4311    fn group(&mut self) -> Option<TransactionId> {
4312        let mut count = 0;
4313        let mut transactions = self.undo_stack.iter();
4314        if let Some(mut transaction) = transactions.next_back() {
4315            while let Some(prev_transaction) = transactions.next_back() {
4316                if !prev_transaction.suppress_grouping
4317                    && transaction.first_edit_at - prev_transaction.last_edit_at
4318                        <= self.group_interval
4319                {
4320                    transaction = prev_transaction;
4321                    count += 1;
4322                } else {
4323                    break;
4324                }
4325            }
4326        }
4327        self.group_trailing(count)
4328    }
4329
4330    fn group_until(&mut self, transaction_id: TransactionId) {
4331        let mut count = 0;
4332        for transaction in self.undo_stack.iter().rev() {
4333            if transaction.id == transaction_id {
4334                self.group_trailing(count);
4335                break;
4336            } else if transaction.suppress_grouping {
4337                break;
4338            } else {
4339                count += 1;
4340            }
4341        }
4342    }
4343
4344    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
4345        let new_len = self.undo_stack.len() - n;
4346        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
4347        if let Some(last_transaction) = transactions_to_keep.last_mut() {
4348            if let Some(transaction) = transactions_to_merge.last() {
4349                last_transaction.last_edit_at = transaction.last_edit_at;
4350            }
4351            for to_merge in transactions_to_merge {
4352                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
4353                    last_transaction
4354                        .buffer_transactions
4355                        .entry(*buffer_id)
4356                        .or_insert(*transaction_id);
4357                }
4358            }
4359        }
4360
4361        self.undo_stack.truncate(new_len);
4362        self.undo_stack.last().map(|t| t.id)
4363    }
4364}
4365
4366impl Excerpt {
4367    fn new(
4368        id: ExcerptId,
4369        locator: Locator,
4370        buffer_id: BufferId,
4371        buffer: BufferSnapshot,
4372        range: ExcerptRange<text::Anchor>,
4373        has_trailing_newline: bool,
4374    ) -> Self {
4375        Excerpt {
4376            id,
4377            locator,
4378            max_buffer_row: range.context.end.to_point(&buffer).row,
4379            text_summary: buffer
4380                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
4381            buffer_id,
4382            buffer,
4383            range,
4384            has_trailing_newline,
4385        }
4386    }
4387
4388    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
4389        let content_start = self.range.context.start.to_offset(&self.buffer);
4390        let chunks_start = content_start + range.start;
4391        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
4392
4393        let footer_height = if self.has_trailing_newline
4394            && range.start <= self.text_summary.len
4395            && range.end > self.text_summary.len
4396        {
4397            1
4398        } else {
4399            0
4400        };
4401
4402        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
4403
4404        ExcerptChunks {
4405            excerpt_id: self.id,
4406            content_chunks,
4407            footer_height,
4408        }
4409    }
4410
4411    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
4412        let content_start = self.range.context.start.to_offset(&self.buffer);
4413        let chunks_start = content_start + range.start;
4414        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
4415        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
4416        excerpt_chunks.footer_height = if self.has_trailing_newline
4417            && range.start <= self.text_summary.len
4418            && range.end > self.text_summary.len
4419        {
4420            1
4421        } else {
4422            0
4423        };
4424    }
4425
4426    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
4427        let content_start = self.range.context.start.to_offset(&self.buffer);
4428        let bytes_start = content_start + range.start;
4429        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
4430        let footer_height = if self.has_trailing_newline
4431            && range.start <= self.text_summary.len
4432            && range.end > self.text_summary.len
4433        {
4434            1
4435        } else {
4436            0
4437        };
4438        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
4439
4440        ExcerptBytes {
4441            content_bytes,
4442            padding_height: footer_height,
4443            reversed: false,
4444        }
4445    }
4446
4447    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
4448        let content_start = self.range.context.start.to_offset(&self.buffer);
4449        let bytes_start = content_start + range.start;
4450        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
4451        let footer_height = if self.has_trailing_newline
4452            && range.start <= self.text_summary.len
4453            && range.end > self.text_summary.len
4454        {
4455            1
4456        } else {
4457            0
4458        };
4459        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
4460
4461        ExcerptBytes {
4462            content_bytes,
4463            padding_height: footer_height,
4464            reversed: true,
4465        }
4466    }
4467
4468    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
4469        if text_anchor
4470            .cmp(&self.range.context.start, &self.buffer)
4471            .is_lt()
4472        {
4473            self.range.context.start
4474        } else if text_anchor
4475            .cmp(&self.range.context.end, &self.buffer)
4476            .is_gt()
4477        {
4478            self.range.context.end
4479        } else {
4480            text_anchor
4481        }
4482    }
4483
4484    fn contains(&self, anchor: &Anchor) -> bool {
4485        Some(self.buffer_id) == anchor.buffer_id
4486            && self
4487                .range
4488                .context
4489                .start
4490                .cmp(&anchor.text_anchor, &self.buffer)
4491                .is_le()
4492            && self
4493                .range
4494                .context
4495                .end
4496                .cmp(&anchor.text_anchor, &self.buffer)
4497                .is_ge()
4498    }
4499
4500    /// The [`Excerpt`]'s start offset in its [`Buffer`]
4501    fn buffer_start_offset(&self) -> usize {
4502        self.range.context.start.to_offset(&self.buffer)
4503    }
4504
4505    /// The [`Excerpt`]'s end offset in its [`Buffer`]
4506    fn buffer_end_offset(&self) -> usize {
4507        self.buffer_start_offset() + self.text_summary.len
4508    }
4509}
4510
4511impl<'a> MultiBufferExcerpt<'a> {
4512    fn new(excerpt: &'a Excerpt, excerpt_offset: usize) -> Self {
4513        MultiBufferExcerpt {
4514            excerpt,
4515            excerpt_offset,
4516        }
4517    }
4518
4519    pub fn buffer(&self) -> &'a BufferSnapshot {
4520        &self.excerpt.buffer
4521    }
4522
4523    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
4524    pub fn map_offset_to_buffer(&self, offset: usize) -> usize {
4525        self.excerpt.buffer_start_offset() + offset.saturating_sub(self.excerpt_offset)
4526    }
4527
4528    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
4529    pub fn map_range_to_buffer(&self, range: Range<usize>) -> Range<usize> {
4530        self.map_offset_to_buffer(range.start)..self.map_offset_to_buffer(range.end)
4531    }
4532
4533    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
4534    pub fn map_offset_from_buffer(&self, buffer_offset: usize) -> usize {
4535        let mut buffer_offset_in_excerpt =
4536            buffer_offset.saturating_sub(self.excerpt.buffer_start_offset());
4537        buffer_offset_in_excerpt =
4538            cmp::min(buffer_offset_in_excerpt, self.excerpt.text_summary.len);
4539
4540        self.excerpt_offset + buffer_offset_in_excerpt
4541    }
4542
4543    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
4544    pub fn map_range_from_buffer(&self, buffer_range: Range<usize>) -> Range<usize> {
4545        self.map_offset_from_buffer(buffer_range.start)
4546            ..self.map_offset_from_buffer(buffer_range.end)
4547    }
4548
4549    /// Returns true if the entirety of the given range is in the buffer's excerpt
4550    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
4551        range.start >= self.excerpt.buffer_start_offset()
4552            && range.end <= self.excerpt.buffer_end_offset()
4553    }
4554}
4555
4556impl ExcerptId {
4557    pub fn min() -> Self {
4558        Self(0)
4559    }
4560
4561    pub fn max() -> Self {
4562        Self(usize::MAX)
4563    }
4564
4565    pub fn to_proto(&self) -> u64 {
4566        self.0 as _
4567    }
4568
4569    pub fn from_proto(proto: u64) -> Self {
4570        Self(proto as _)
4571    }
4572
4573    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
4574        let a = snapshot.excerpt_locator_for_id(*self);
4575        let b = snapshot.excerpt_locator_for_id(*other);
4576        a.cmp(b).then_with(|| self.0.cmp(&other.0))
4577    }
4578}
4579
4580impl From<ExcerptId> for usize {
4581    fn from(val: ExcerptId) -> Self {
4582        val.0
4583    }
4584}
4585
4586impl fmt::Debug for Excerpt {
4587    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4588        f.debug_struct("Excerpt")
4589            .field("id", &self.id)
4590            .field("locator", &self.locator)
4591            .field("buffer_id", &self.buffer_id)
4592            .field("range", &self.range)
4593            .field("text_summary", &self.text_summary)
4594            .field("has_trailing_newline", &self.has_trailing_newline)
4595            .finish()
4596    }
4597}
4598
4599impl sum_tree::Item for Excerpt {
4600    type Summary = ExcerptSummary;
4601
4602    fn summary(&self, _cx: &()) -> Self::Summary {
4603        let mut text = self.text_summary.clone();
4604        if self.has_trailing_newline {
4605            text += TextSummary::from("\n");
4606        }
4607        ExcerptSummary {
4608            excerpt_id: self.id,
4609            excerpt_locator: self.locator.clone(),
4610            max_buffer_row: MultiBufferRow(self.max_buffer_row),
4611            text,
4612        }
4613    }
4614}
4615
4616impl sum_tree::Item for ExcerptIdMapping {
4617    type Summary = ExcerptId;
4618
4619    fn summary(&self, _cx: &()) -> Self::Summary {
4620        self.id
4621    }
4622}
4623
4624impl sum_tree::KeyedItem for ExcerptIdMapping {
4625    type Key = ExcerptId;
4626
4627    fn key(&self) -> Self::Key {
4628        self.id
4629    }
4630}
4631
4632impl sum_tree::Summary for ExcerptId {
4633    type Context = ();
4634
4635    fn zero(_cx: &()) -> Self {
4636        Default::default()
4637    }
4638
4639    fn add_summary(&mut self, other: &Self, _: &()) {
4640        *self = *other;
4641    }
4642}
4643
4644impl sum_tree::Summary for ExcerptSummary {
4645    type Context = ();
4646
4647    fn zero(_cx: &()) -> Self {
4648        Default::default()
4649    }
4650
4651    fn add_summary(&mut self, summary: &Self, _: &()) {
4652        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
4653        self.excerpt_locator = summary.excerpt_locator.clone();
4654        self.text.add_summary(&summary.text, &());
4655        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
4656    }
4657}
4658
4659impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
4660    fn zero(_cx: &()) -> Self {
4661        Default::default()
4662    }
4663
4664    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4665        *self += &summary.text;
4666    }
4667}
4668
4669impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
4670    fn zero(_cx: &()) -> Self {
4671        Default::default()
4672    }
4673
4674    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4675        *self += summary.text.len;
4676    }
4677}
4678
4679impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
4680    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4681        Ord::cmp(self, &cursor_location.text.len)
4682    }
4683}
4684
4685impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
4686    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
4687        Ord::cmp(&Some(self), cursor_location)
4688    }
4689}
4690
4691impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
4692    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4693        Ord::cmp(self, &cursor_location.excerpt_locator)
4694    }
4695}
4696
4697impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
4698    fn zero(_cx: &()) -> Self {
4699        Default::default()
4700    }
4701
4702    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4703        *self += summary.text.len_utf16;
4704    }
4705}
4706
4707impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
4708    fn zero(_cx: &()) -> Self {
4709        Default::default()
4710    }
4711
4712    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4713        *self += summary.text.lines;
4714    }
4715}
4716
4717impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
4718    fn zero(_cx: &()) -> Self {
4719        Default::default()
4720    }
4721
4722    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4723        *self += summary.text.lines_utf16()
4724    }
4725}
4726
4727impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
4728    fn zero(_cx: &()) -> Self {
4729        Default::default()
4730    }
4731
4732    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4733        *self = Some(&summary.excerpt_locator);
4734    }
4735}
4736
4737impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
4738    fn zero(_cx: &()) -> Self {
4739        Default::default()
4740    }
4741
4742    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4743        *self = Some(summary.excerpt_id);
4744    }
4745}
4746
4747impl<'a> MultiBufferRows<'a> {
4748    pub fn seek(&mut self, row: MultiBufferRow) {
4749        self.buffer_row_range = 0..0;
4750
4751        self.excerpts
4752            .seek_forward(&Point::new(row.0, 0), Bias::Right, &());
4753        if self.excerpts.item().is_none() {
4754            self.excerpts.prev(&());
4755
4756            if self.excerpts.item().is_none() && row.0 == 0 {
4757                self.buffer_row_range = 0..1;
4758                return;
4759            }
4760        }
4761
4762        if let Some(excerpt) = self.excerpts.item() {
4763            let overshoot = row.0 - self.excerpts.start().row;
4764            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4765            self.buffer_row_range.start = excerpt_start + overshoot;
4766            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
4767        }
4768    }
4769}
4770
4771impl<'a> Iterator for MultiBufferRows<'a> {
4772    type Item = Option<u32>;
4773
4774    fn next(&mut self) -> Option<Self::Item> {
4775        loop {
4776            if !self.buffer_row_range.is_empty() {
4777                let row = Some(self.buffer_row_range.start);
4778                self.buffer_row_range.start += 1;
4779                return Some(row);
4780            }
4781            self.excerpts.item()?;
4782            self.excerpts.next(&());
4783            let excerpt = self.excerpts.item()?;
4784            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4785            self.buffer_row_range.end =
4786                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
4787        }
4788    }
4789}
4790
4791impl<'a> MultiBufferChunks<'a> {
4792    pub fn offset(&self) -> usize {
4793        self.range.start
4794    }
4795
4796    pub fn seek(&mut self, new_range: Range<usize>) {
4797        self.range = new_range.clone();
4798        self.excerpts.seek(&new_range.start, Bias::Right, &());
4799        if let Some(excerpt) = self.excerpts.item() {
4800            let excerpt_start = self.excerpts.start();
4801            if let Some(excerpt_chunks) = self
4802                .excerpt_chunks
4803                .as_mut()
4804                .filter(|chunks| excerpt.id == chunks.excerpt_id)
4805            {
4806                excerpt.seek_chunks(
4807                    excerpt_chunks,
4808                    self.range.start - excerpt_start..self.range.end - excerpt_start,
4809                );
4810            } else {
4811                self.excerpt_chunks = Some(excerpt.chunks_in_range(
4812                    self.range.start - excerpt_start..self.range.end - excerpt_start,
4813                    self.language_aware,
4814                ));
4815            }
4816        } else {
4817            self.excerpt_chunks = None;
4818        }
4819    }
4820}
4821
4822impl<'a> Iterator for MultiBufferChunks<'a> {
4823    type Item = Chunk<'a>;
4824
4825    fn next(&mut self) -> Option<Self::Item> {
4826        if self.range.is_empty() {
4827            None
4828        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
4829            self.range.start += chunk.text.len();
4830            Some(chunk)
4831        } else {
4832            self.excerpts.next(&());
4833            let excerpt = self.excerpts.item()?;
4834            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4835                0..self.range.end - self.excerpts.start(),
4836                self.language_aware,
4837            ));
4838            self.next()
4839        }
4840    }
4841}
4842
4843impl<'a> MultiBufferBytes<'a> {
4844    fn consume(&mut self, len: usize) {
4845        self.range.start += len;
4846        self.chunk = &self.chunk[len..];
4847
4848        if !self.range.is_empty() && self.chunk.is_empty() {
4849            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4850                self.chunk = chunk;
4851            } else {
4852                self.excerpts.next(&());
4853                if let Some(excerpt) = self.excerpts.item() {
4854                    let mut excerpt_bytes =
4855                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4856                    self.chunk = excerpt_bytes.next().unwrap();
4857                    self.excerpt_bytes = Some(excerpt_bytes);
4858                }
4859            }
4860        }
4861    }
4862}
4863
4864impl<'a> Iterator for MultiBufferBytes<'a> {
4865    type Item = &'a [u8];
4866
4867    fn next(&mut self) -> Option<Self::Item> {
4868        let chunk = self.chunk;
4869        if chunk.is_empty() {
4870            None
4871        } else {
4872            self.consume(chunk.len());
4873            Some(chunk)
4874        }
4875    }
4876}
4877
4878impl<'a> io::Read for MultiBufferBytes<'a> {
4879    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4880        let len = cmp::min(buf.len(), self.chunk.len());
4881        buf[..len].copy_from_slice(&self.chunk[..len]);
4882        if len > 0 {
4883            self.consume(len);
4884        }
4885        Ok(len)
4886    }
4887}
4888
4889impl<'a> ReversedMultiBufferBytes<'a> {
4890    fn consume(&mut self, len: usize) {
4891        self.range.end -= len;
4892        self.chunk = &self.chunk[..self.chunk.len() - len];
4893
4894        if !self.range.is_empty() && self.chunk.is_empty() {
4895            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4896                self.chunk = chunk;
4897            } else {
4898                self.excerpts.prev(&());
4899                if let Some(excerpt) = self.excerpts.item() {
4900                    let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
4901                        self.range.start.saturating_sub(*self.excerpts.start())..usize::MAX,
4902                    );
4903                    self.chunk = excerpt_bytes.next().unwrap();
4904                    self.excerpt_bytes = Some(excerpt_bytes);
4905                }
4906            }
4907        }
4908    }
4909}
4910
4911impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
4912    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4913        let len = cmp::min(buf.len(), self.chunk.len());
4914        buf[..len].copy_from_slice(&self.chunk[..len]);
4915        buf[..len].reverse();
4916        if len > 0 {
4917            self.consume(len);
4918        }
4919        Ok(len)
4920    }
4921}
4922impl<'a> Iterator for ExcerptBytes<'a> {
4923    type Item = &'a [u8];
4924
4925    fn next(&mut self) -> Option<Self::Item> {
4926        if self.reversed && self.padding_height > 0 {
4927            let result = &NEWLINES[..self.padding_height];
4928            self.padding_height = 0;
4929            return Some(result);
4930        }
4931
4932        if let Some(chunk) = self.content_bytes.next() {
4933            if !chunk.is_empty() {
4934                return Some(chunk);
4935            }
4936        }
4937
4938        if self.padding_height > 0 {
4939            let result = &NEWLINES[..self.padding_height];
4940            self.padding_height = 0;
4941            return Some(result);
4942        }
4943
4944        None
4945    }
4946}
4947
4948impl<'a> Iterator for ExcerptChunks<'a> {
4949    type Item = Chunk<'a>;
4950
4951    fn next(&mut self) -> Option<Self::Item> {
4952        if let Some(chunk) = self.content_chunks.next() {
4953            return Some(chunk);
4954        }
4955
4956        if self.footer_height > 0 {
4957            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
4958            self.footer_height = 0;
4959            return Some(Chunk {
4960                text,
4961                ..Default::default()
4962            });
4963        }
4964
4965        None
4966    }
4967}
4968
4969impl ToOffset for Point {
4970    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4971        snapshot.point_to_offset(*self)
4972    }
4973}
4974
4975impl ToOffset for usize {
4976    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4977        assert!(*self <= snapshot.len(), "offset is out of range");
4978        *self
4979    }
4980}
4981
4982impl ToOffset for OffsetUtf16 {
4983    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4984        snapshot.offset_utf16_to_offset(*self)
4985    }
4986}
4987
4988impl ToOffset for PointUtf16 {
4989    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4990        snapshot.point_utf16_to_offset(*self)
4991    }
4992}
4993
4994impl ToOffsetUtf16 for OffsetUtf16 {
4995    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4996        *self
4997    }
4998}
4999
5000impl ToOffsetUtf16 for usize {
5001    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
5002        snapshot.offset_to_offset_utf16(*self)
5003    }
5004}
5005
5006impl ToPoint for usize {
5007    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
5008        snapshot.offset_to_point(*self)
5009    }
5010}
5011
5012impl ToPoint for Point {
5013    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
5014        *self
5015    }
5016}
5017
5018impl ToPointUtf16 for usize {
5019    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
5020        snapshot.offset_to_point_utf16(*self)
5021    }
5022}
5023
5024impl ToPointUtf16 for Point {
5025    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
5026        snapshot.point_to_point_utf16(*self)
5027    }
5028}
5029
5030impl ToPointUtf16 for PointUtf16 {
5031    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
5032        *self
5033    }
5034}
5035
5036pub fn build_excerpt_ranges<T>(
5037    buffer: &BufferSnapshot,
5038    ranges: &[Range<T>],
5039    context_line_count: u32,
5040) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
5041where
5042    T: text::ToPoint,
5043{
5044    let max_point = buffer.max_point();
5045    let mut range_counts = Vec::new();
5046    let mut excerpt_ranges = Vec::new();
5047    let mut range_iter = ranges
5048        .iter()
5049        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
5050        .peekable();
5051    while let Some(range) = range_iter.next() {
5052        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
5053        let row = (range.end.row + context_line_count).min(max_point.row);
5054        let mut excerpt_end = Point::new(row, buffer.line_len(row));
5055
5056        let mut ranges_in_excerpt = 1;
5057
5058        while let Some(next_range) = range_iter.peek() {
5059            if next_range.start.row <= excerpt_end.row + context_line_count {
5060                let row = (next_range.end.row + context_line_count).min(max_point.row);
5061                excerpt_end = Point::new(row, buffer.line_len(row));
5062
5063                ranges_in_excerpt += 1;
5064                range_iter.next();
5065            } else {
5066                break;
5067            }
5068        }
5069
5070        excerpt_ranges.push(ExcerptRange {
5071            context: excerpt_start..excerpt_end,
5072            primary: Some(range),
5073        });
5074        range_counts.push(ranges_in_excerpt);
5075    }
5076
5077    (excerpt_ranges, range_counts)
5078}
5079
5080#[cfg(test)]
5081mod tests {
5082    use super::*;
5083    use gpui::{AppContext, Context, TestAppContext};
5084    use language::{Buffer, Rope};
5085    use parking_lot::RwLock;
5086    use rand::prelude::*;
5087    use settings::SettingsStore;
5088    use std::env;
5089    use util::test::sample_text;
5090
5091    #[ctor::ctor]
5092    fn init_logger() {
5093        if std::env::var("RUST_LOG").is_ok() {
5094            env_logger::init();
5095        }
5096    }
5097
5098    #[gpui::test]
5099    fn test_singleton(cx: &mut AppContext) {
5100        let buffer = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
5101        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
5102
5103        let snapshot = multibuffer.read(cx).snapshot(cx);
5104        assert_eq!(snapshot.text(), buffer.read(cx).text());
5105
5106        assert_eq!(
5107            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5108            (0..buffer.read(cx).row_count())
5109                .map(Some)
5110                .collect::<Vec<_>>()
5111        );
5112
5113        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
5114        let snapshot = multibuffer.read(cx).snapshot(cx);
5115
5116        assert_eq!(snapshot.text(), buffer.read(cx).text());
5117        assert_eq!(
5118            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5119            (0..buffer.read(cx).row_count())
5120                .map(Some)
5121                .collect::<Vec<_>>()
5122        );
5123    }
5124
5125    #[gpui::test]
5126    fn test_remote(cx: &mut AppContext) {
5127        let host_buffer = cx.new_model(|cx| Buffer::local("a", cx));
5128        let guest_buffer = cx.new_model(|cx| {
5129            let state = host_buffer.read(cx).to_proto(cx);
5130            let ops = cx
5131                .background_executor()
5132                .block(host_buffer.read(cx).serialize_ops(None, cx));
5133            let mut buffer = Buffer::from_proto(1, Capability::ReadWrite, state, None).unwrap();
5134            buffer.apply_ops(
5135                ops.into_iter()
5136                    .map(|op| language::proto::deserialize_operation(op).unwrap()),
5137                cx,
5138            );
5139            buffer
5140        });
5141        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
5142        let snapshot = multibuffer.read(cx).snapshot(cx);
5143        assert_eq!(snapshot.text(), "a");
5144
5145        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
5146        let snapshot = multibuffer.read(cx).snapshot(cx);
5147        assert_eq!(snapshot.text(), "ab");
5148
5149        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
5150        let snapshot = multibuffer.read(cx).snapshot(cx);
5151        assert_eq!(snapshot.text(), "abc");
5152    }
5153
5154    #[gpui::test]
5155    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
5156        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
5157        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
5158        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5159
5160        let events = Arc::new(RwLock::new(Vec::<Event>::new()));
5161        multibuffer.update(cx, |_, cx| {
5162            let events = events.clone();
5163            cx.subscribe(&multibuffer, move |_, _, event, _| {
5164                if let Event::Edited { .. } = event {
5165                    events.write().push(event.clone())
5166                }
5167            })
5168            .detach();
5169        });
5170
5171        let subscription = multibuffer.update(cx, |multibuffer, cx| {
5172            let subscription = multibuffer.subscribe();
5173            multibuffer.push_excerpts(
5174                buffer_1.clone(),
5175                [ExcerptRange {
5176                    context: Point::new(1, 2)..Point::new(2, 5),
5177                    primary: None,
5178                }],
5179                cx,
5180            );
5181            assert_eq!(
5182                subscription.consume().into_inner(),
5183                [Edit {
5184                    old: 0..0,
5185                    new: 0..10
5186                }]
5187            );
5188
5189            multibuffer.push_excerpts(
5190                buffer_1.clone(),
5191                [ExcerptRange {
5192                    context: Point::new(3, 3)..Point::new(4, 4),
5193                    primary: None,
5194                }],
5195                cx,
5196            );
5197            multibuffer.push_excerpts(
5198                buffer_2.clone(),
5199                [ExcerptRange {
5200                    context: Point::new(3, 1)..Point::new(3, 3),
5201                    primary: None,
5202                }],
5203                cx,
5204            );
5205            assert_eq!(
5206                subscription.consume().into_inner(),
5207                [Edit {
5208                    old: 10..10,
5209                    new: 10..22
5210                }]
5211            );
5212
5213            subscription
5214        });
5215
5216        // Adding excerpts emits an edited event.
5217        assert_eq!(
5218            events.read().as_slice(),
5219            &[
5220                Event::Edited {
5221                    singleton_buffer_edited: false
5222                },
5223                Event::Edited {
5224                    singleton_buffer_edited: false
5225                },
5226                Event::Edited {
5227                    singleton_buffer_edited: false
5228                }
5229            ]
5230        );
5231
5232        let snapshot = multibuffer.read(cx).snapshot(cx);
5233        assert_eq!(
5234            snapshot.text(),
5235            concat!(
5236                "bbbb\n",  // Preserve newlines
5237                "ccccc\n", //
5238                "ddd\n",   //
5239                "eeee\n",  //
5240                "jj"       //
5241            )
5242        );
5243        assert_eq!(
5244            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5245            [Some(1), Some(2), Some(3), Some(4), Some(3)]
5246        );
5247        assert_eq!(
5248            snapshot.buffer_rows(MultiBufferRow(2)).collect::<Vec<_>>(),
5249            [Some(3), Some(4), Some(3)]
5250        );
5251        assert_eq!(
5252            snapshot.buffer_rows(MultiBufferRow(4)).collect::<Vec<_>>(),
5253            [Some(3)]
5254        );
5255        assert_eq!(
5256            snapshot.buffer_rows(MultiBufferRow(5)).collect::<Vec<_>>(),
5257            []
5258        );
5259
5260        assert_eq!(
5261            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
5262            &[
5263                (MultiBufferRow(0), "bbbb\nccccc".to_string(), true),
5264                (MultiBufferRow(2), "ddd\neeee".to_string(), false),
5265                (MultiBufferRow(4), "jj".to_string(), true),
5266            ]
5267        );
5268        assert_eq!(
5269            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
5270            &[(MultiBufferRow(0), "bbbb\nccccc".to_string(), true)]
5271        );
5272        assert_eq!(
5273            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
5274            &[]
5275        );
5276        assert_eq!(
5277            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
5278            &[]
5279        );
5280        assert_eq!(
5281            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
5282            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5283        );
5284        assert_eq!(
5285            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
5286            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5287        );
5288        assert_eq!(
5289            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
5290            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5291        );
5292        assert_eq!(
5293            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
5294            &[(MultiBufferRow(4), "jj".to_string(), true)]
5295        );
5296        assert_eq!(
5297            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
5298            &[]
5299        );
5300
5301        buffer_1.update(cx, |buffer, cx| {
5302            let text = "\n";
5303            buffer.edit(
5304                [
5305                    (Point::new(0, 0)..Point::new(0, 0), text),
5306                    (Point::new(2, 1)..Point::new(2, 3), text),
5307                ],
5308                None,
5309                cx,
5310            );
5311        });
5312
5313        let snapshot = multibuffer.read(cx).snapshot(cx);
5314        assert_eq!(
5315            snapshot.text(),
5316            concat!(
5317                "bbbb\n", // Preserve newlines
5318                "c\n",    //
5319                "cc\n",   //
5320                "ddd\n",  //
5321                "eeee\n", //
5322                "jj"      //
5323            )
5324        );
5325
5326        assert_eq!(
5327            subscription.consume().into_inner(),
5328            [Edit {
5329                old: 6..8,
5330                new: 6..7
5331            }]
5332        );
5333
5334        let snapshot = multibuffer.read(cx).snapshot(cx);
5335        assert_eq!(
5336            snapshot.clip_point(Point::new(0, 5), Bias::Left),
5337            Point::new(0, 4)
5338        );
5339        assert_eq!(
5340            snapshot.clip_point(Point::new(0, 5), Bias::Right),
5341            Point::new(0, 4)
5342        );
5343        assert_eq!(
5344            snapshot.clip_point(Point::new(5, 1), Bias::Right),
5345            Point::new(5, 1)
5346        );
5347        assert_eq!(
5348            snapshot.clip_point(Point::new(5, 2), Bias::Right),
5349            Point::new(5, 2)
5350        );
5351        assert_eq!(
5352            snapshot.clip_point(Point::new(5, 3), Bias::Right),
5353            Point::new(5, 2)
5354        );
5355
5356        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
5357            let (buffer_2_excerpt_id, _) =
5358                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
5359            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
5360            multibuffer.snapshot(cx)
5361        });
5362
5363        assert_eq!(
5364            snapshot.text(),
5365            concat!(
5366                "bbbb\n", // Preserve newlines
5367                "c\n",    //
5368                "cc\n",   //
5369                "ddd\n",  //
5370                "eeee",   //
5371            )
5372        );
5373
5374        fn boundaries_in_range(
5375            range: Range<Point>,
5376            snapshot: &MultiBufferSnapshot,
5377        ) -> Vec<(MultiBufferRow, String, bool)> {
5378            snapshot
5379                .excerpt_boundaries_in_range(range)
5380                .filter_map(|boundary| {
5381                    let starts_new_buffer = boundary.starts_new_buffer();
5382                    boundary.next.map(|next| {
5383                        (
5384                            boundary.row,
5385                            next.buffer
5386                                .text_for_range(next.range.context)
5387                                .collect::<String>(),
5388                            starts_new_buffer,
5389                        )
5390                    })
5391                })
5392                .collect::<Vec<_>>()
5393        }
5394    }
5395
5396    #[gpui::test]
5397    fn test_excerpt_events(cx: &mut AppContext) {
5398        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'a'), cx));
5399        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'm'), cx));
5400
5401        let leader_multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5402        let follower_multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5403        let follower_edit_event_count = Arc::new(RwLock::new(0));
5404
5405        follower_multibuffer.update(cx, |_, cx| {
5406            let follower_edit_event_count = follower_edit_event_count.clone();
5407            cx.subscribe(
5408                &leader_multibuffer,
5409                move |follower, _, event, cx| match event.clone() {
5410                    Event::ExcerptsAdded {
5411                        buffer,
5412                        predecessor,
5413                        excerpts,
5414                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
5415                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
5416                    Event::Edited { .. } => {
5417                        *follower_edit_event_count.write() += 1;
5418                    }
5419                    _ => {}
5420                },
5421            )
5422            .detach();
5423        });
5424
5425        leader_multibuffer.update(cx, |leader, cx| {
5426            leader.push_excerpts(
5427                buffer_1.clone(),
5428                [
5429                    ExcerptRange {
5430                        context: 0..8,
5431                        primary: None,
5432                    },
5433                    ExcerptRange {
5434                        context: 12..16,
5435                        primary: None,
5436                    },
5437                ],
5438                cx,
5439            );
5440            leader.insert_excerpts_after(
5441                leader.excerpt_ids()[0],
5442                buffer_2.clone(),
5443                [
5444                    ExcerptRange {
5445                        context: 0..5,
5446                        primary: None,
5447                    },
5448                    ExcerptRange {
5449                        context: 10..15,
5450                        primary: None,
5451                    },
5452                ],
5453                cx,
5454            )
5455        });
5456        assert_eq!(
5457            leader_multibuffer.read(cx).snapshot(cx).text(),
5458            follower_multibuffer.read(cx).snapshot(cx).text(),
5459        );
5460        assert_eq!(*follower_edit_event_count.read(), 2);
5461
5462        leader_multibuffer.update(cx, |leader, cx| {
5463            let excerpt_ids = leader.excerpt_ids();
5464            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
5465        });
5466        assert_eq!(
5467            leader_multibuffer.read(cx).snapshot(cx).text(),
5468            follower_multibuffer.read(cx).snapshot(cx).text(),
5469        );
5470        assert_eq!(*follower_edit_event_count.read(), 3);
5471
5472        // Removing an empty set of excerpts is a noop.
5473        leader_multibuffer.update(cx, |leader, cx| {
5474            leader.remove_excerpts([], cx);
5475        });
5476        assert_eq!(
5477            leader_multibuffer.read(cx).snapshot(cx).text(),
5478            follower_multibuffer.read(cx).snapshot(cx).text(),
5479        );
5480        assert_eq!(*follower_edit_event_count.read(), 3);
5481
5482        // Adding an empty set of excerpts is a noop.
5483        leader_multibuffer.update(cx, |leader, cx| {
5484            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
5485        });
5486        assert_eq!(
5487            leader_multibuffer.read(cx).snapshot(cx).text(),
5488            follower_multibuffer.read(cx).snapshot(cx).text(),
5489        );
5490        assert_eq!(*follower_edit_event_count.read(), 3);
5491
5492        leader_multibuffer.update(cx, |leader, cx| {
5493            leader.clear(cx);
5494        });
5495        assert_eq!(
5496            leader_multibuffer.read(cx).snapshot(cx).text(),
5497            follower_multibuffer.read(cx).snapshot(cx).text(),
5498        );
5499        assert_eq!(*follower_edit_event_count.read(), 4);
5500    }
5501
5502    #[gpui::test]
5503    fn test_expand_excerpts(cx: &mut AppContext) {
5504        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5505        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5506
5507        multibuffer.update(cx, |multibuffer, cx| {
5508            multibuffer.push_excerpts_with_context_lines(
5509                buffer.clone(),
5510                vec![
5511                    // Note that in this test, this first excerpt
5512                    // does not contain a new line
5513                    Point::new(3, 2)..Point::new(3, 3),
5514                    Point::new(7, 1)..Point::new(7, 3),
5515                    Point::new(15, 0)..Point::new(15, 0),
5516                ],
5517                1,
5518                cx,
5519            )
5520        });
5521
5522        let snapshot = multibuffer.read(cx).snapshot(cx);
5523
5524        assert_eq!(
5525            snapshot.text(),
5526            concat!(
5527                "ccc\n", //
5528                "ddd\n", //
5529                "eee",   //
5530                "\n",    // End of excerpt
5531                "ggg\n", //
5532                "hhh\n", //
5533                "iii",   //
5534                "\n",    // End of excerpt
5535                "ooo\n", //
5536                "ppp\n", //
5537                "qqq",   // End of excerpt
5538            )
5539        );
5540        drop(snapshot);
5541
5542        multibuffer.update(cx, |multibuffer, cx| {
5543            multibuffer.expand_excerpts(
5544                multibuffer.excerpt_ids(),
5545                1,
5546                ExpandExcerptDirection::UpAndDown,
5547                cx,
5548            )
5549        });
5550
5551        let snapshot = multibuffer.read(cx).snapshot(cx);
5552
5553        // Expanding context lines causes the line containing 'fff' to appear in two different excerpts.
5554        // We don't attempt to merge them, because removing the excerpt could create inconsistency with other layers
5555        // that are tracking excerpt ids.
5556        assert_eq!(
5557            snapshot.text(),
5558            concat!(
5559                "bbb\n", //
5560                "ccc\n", //
5561                "ddd\n", //
5562                "eee\n", //
5563                "fff\n", // End of excerpt
5564                "fff\n", //
5565                "ggg\n", //
5566                "hhh\n", //
5567                "iii\n", //
5568                "jjj\n", // End of excerpt
5569                "nnn\n", //
5570                "ooo\n", //
5571                "ppp\n", //
5572                "qqq\n", //
5573                "rrr",   // End of excerpt
5574            )
5575        );
5576    }
5577
5578    #[gpui::test]
5579    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
5580        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5581        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5582        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
5583            multibuffer.push_excerpts_with_context_lines(
5584                buffer.clone(),
5585                vec![
5586                    // Note that in this test, this first excerpt
5587                    // does contain a new line
5588                    Point::new(3, 2)..Point::new(4, 2),
5589                    Point::new(7, 1)..Point::new(7, 3),
5590                    Point::new(15, 0)..Point::new(15, 0),
5591                ],
5592                2,
5593                cx,
5594            )
5595        });
5596
5597        let snapshot = multibuffer.read(cx).snapshot(cx);
5598        assert_eq!(
5599            snapshot.text(),
5600            concat!(
5601                "bbb\n", // Preserve newlines
5602                "ccc\n", //
5603                "ddd\n", //
5604                "eee\n", //
5605                "fff\n", //
5606                "ggg\n", //
5607                "hhh\n", //
5608                "iii\n", //
5609                "jjj\n", //
5610                "nnn\n", //
5611                "ooo\n", //
5612                "ppp\n", //
5613                "qqq\n", //
5614                "rrr",   //
5615            )
5616        );
5617
5618        assert_eq!(
5619            anchor_ranges
5620                .iter()
5621                .map(|range| range.to_point(&snapshot))
5622                .collect::<Vec<_>>(),
5623            vec![
5624                Point::new(2, 2)..Point::new(3, 2),
5625                Point::new(6, 1)..Point::new(6, 3),
5626                Point::new(11, 0)..Point::new(11, 0)
5627            ]
5628        );
5629    }
5630
5631    #[gpui::test(iterations = 100)]
5632    async fn test_push_multiple_excerpts_with_context_lines(cx: &mut TestAppContext) {
5633        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5634        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(15, 4, 'a'), cx));
5635        let snapshot_1 = buffer_1.update(cx, |buffer, _| buffer.snapshot());
5636        let snapshot_2 = buffer_2.update(cx, |buffer, _| buffer.snapshot());
5637        let ranges_1 = vec![
5638            snapshot_1.anchor_before(Point::new(3, 2))..snapshot_1.anchor_before(Point::new(4, 2)),
5639            snapshot_1.anchor_before(Point::new(7, 1))..snapshot_1.anchor_before(Point::new(7, 3)),
5640            snapshot_1.anchor_before(Point::new(15, 0))
5641                ..snapshot_1.anchor_before(Point::new(15, 0)),
5642        ];
5643        let ranges_2 = vec![
5644            snapshot_2.anchor_before(Point::new(2, 1))..snapshot_2.anchor_before(Point::new(3, 1)),
5645            snapshot_2.anchor_before(Point::new(10, 0))
5646                ..snapshot_2.anchor_before(Point::new(10, 2)),
5647        ];
5648
5649        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5650        let anchor_ranges = multibuffer
5651            .update(cx, |multibuffer, cx| {
5652                multibuffer.push_multiple_excerpts_with_context_lines(
5653                    vec![(buffer_1.clone(), ranges_1), (buffer_2.clone(), ranges_2)],
5654                    2,
5655                    cx,
5656                )
5657            })
5658            .await;
5659
5660        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
5661        assert_eq!(
5662            snapshot.text(),
5663            concat!(
5664                "bbb\n", // buffer_1
5665                "ccc\n", //
5666                "ddd\n", // <-- excerpt 1
5667                "eee\n", // <-- excerpt 1
5668                "fff\n", //
5669                "ggg\n", //
5670                "hhh\n", // <-- excerpt 2
5671                "iii\n", //
5672                "jjj\n", //
5673                //
5674                "nnn\n", //
5675                "ooo\n", //
5676                "ppp\n", // <-- excerpt 3
5677                "qqq\n", //
5678                "rrr\n", //
5679                //
5680                "aaaa\n", // buffer 2
5681                "bbbb\n", //
5682                "cccc\n", // <-- excerpt 4
5683                "dddd\n", // <-- excerpt 4
5684                "eeee\n", //
5685                "ffff\n", //
5686                //
5687                "iiii\n", //
5688                "jjjj\n", //
5689                "kkkk\n", // <-- excerpt 5
5690                "llll\n", //
5691                "mmmm",   //
5692            )
5693        );
5694
5695        assert_eq!(
5696            anchor_ranges
5697                .iter()
5698                .map(|range| range.to_point(&snapshot))
5699                .collect::<Vec<_>>(),
5700            vec![
5701                Point::new(2, 2)..Point::new(3, 2),
5702                Point::new(6, 1)..Point::new(6, 3),
5703                Point::new(11, 0)..Point::new(11, 0),
5704                Point::new(16, 1)..Point::new(17, 1),
5705                Point::new(22, 0)..Point::new(22, 2)
5706            ]
5707        );
5708    }
5709
5710    #[gpui::test]
5711    fn test_empty_multibuffer(cx: &mut AppContext) {
5712        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5713
5714        let snapshot = multibuffer.read(cx).snapshot(cx);
5715        assert_eq!(snapshot.text(), "");
5716        assert_eq!(
5717            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5718            &[Some(0)]
5719        );
5720        assert_eq!(
5721            snapshot.buffer_rows(MultiBufferRow(1)).collect::<Vec<_>>(),
5722            &[]
5723        );
5724    }
5725
5726    #[gpui::test]
5727    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
5728        let buffer = cx.new_model(|cx| Buffer::local("abcd", cx));
5729        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
5730        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5731        buffer.update(cx, |buffer, cx| {
5732            buffer.edit([(0..0, "X")], None, cx);
5733            buffer.edit([(5..5, "Y")], None, cx);
5734        });
5735        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5736
5737        assert_eq!(old_snapshot.text(), "abcd");
5738        assert_eq!(new_snapshot.text(), "XabcdY");
5739
5740        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5741        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5742        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
5743        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
5744    }
5745
5746    #[gpui::test]
5747    fn test_multibuffer_anchors(cx: &mut AppContext) {
5748        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5749        let buffer_2 = cx.new_model(|cx| Buffer::local("efghi", cx));
5750        let multibuffer = cx.new_model(|cx| {
5751            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
5752            multibuffer.push_excerpts(
5753                buffer_1.clone(),
5754                [ExcerptRange {
5755                    context: 0..4,
5756                    primary: None,
5757                }],
5758                cx,
5759            );
5760            multibuffer.push_excerpts(
5761                buffer_2.clone(),
5762                [ExcerptRange {
5763                    context: 0..5,
5764                    primary: None,
5765                }],
5766                cx,
5767            );
5768            multibuffer
5769        });
5770        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5771
5772        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
5773        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
5774        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5775        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5776        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5777        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5778
5779        buffer_1.update(cx, |buffer, cx| {
5780            buffer.edit([(0..0, "W")], None, cx);
5781            buffer.edit([(5..5, "X")], None, cx);
5782        });
5783        buffer_2.update(cx, |buffer, cx| {
5784            buffer.edit([(0..0, "Y")], None, cx);
5785            buffer.edit([(6..6, "Z")], None, cx);
5786        });
5787        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5788
5789        assert_eq!(old_snapshot.text(), "abcd\nefghi");
5790        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
5791
5792        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5793        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5794        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
5795        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
5796        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
5797        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
5798        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
5799        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
5800        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
5801        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
5802    }
5803
5804    #[gpui::test]
5805    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
5806        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5807        let buffer_2 = cx.new_model(|cx| Buffer::local("ABCDEFGHIJKLMNOP", cx));
5808        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5809
5810        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
5811        // Add an excerpt from buffer 1 that spans this new insertion.
5812        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
5813        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
5814            multibuffer
5815                .push_excerpts(
5816                    buffer_1.clone(),
5817                    [ExcerptRange {
5818                        context: 0..7,
5819                        primary: None,
5820                    }],
5821                    cx,
5822                )
5823                .pop()
5824                .unwrap()
5825        });
5826
5827        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
5828        assert_eq!(snapshot_1.text(), "abcd123");
5829
5830        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
5831        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
5832            multibuffer.remove_excerpts([excerpt_id_1], cx);
5833            let mut ids = multibuffer
5834                .push_excerpts(
5835                    buffer_2.clone(),
5836                    [
5837                        ExcerptRange {
5838                            context: 0..4,
5839                            primary: None,
5840                        },
5841                        ExcerptRange {
5842                            context: 6..10,
5843                            primary: None,
5844                        },
5845                        ExcerptRange {
5846                            context: 12..16,
5847                            primary: None,
5848                        },
5849                    ],
5850                    cx,
5851                )
5852                .into_iter();
5853            (ids.next().unwrap(), ids.next().unwrap())
5854        });
5855        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
5856        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
5857
5858        // The old excerpt id doesn't get reused.
5859        assert_ne!(excerpt_id_2, excerpt_id_1);
5860
5861        // Resolve some anchors from the previous snapshot in the new snapshot.
5862        // The current excerpts are from a different buffer, so we don't attempt to
5863        // resolve the old text anchor in the new buffer.
5864        assert_eq!(
5865            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
5866            0
5867        );
5868        assert_eq!(
5869            snapshot_2.summaries_for_anchors::<usize, _>(&[
5870                snapshot_1.anchor_before(2),
5871                snapshot_1.anchor_after(3)
5872            ]),
5873            vec![0, 0]
5874        );
5875
5876        // Refresh anchors from the old snapshot. The return value indicates that both
5877        // anchors lost their original excerpt.
5878        let refresh =
5879            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
5880        assert_eq!(
5881            refresh,
5882            &[
5883                (0, snapshot_2.anchor_before(0), false),
5884                (1, snapshot_2.anchor_after(0), false),
5885            ]
5886        );
5887
5888        // Replace the middle excerpt with a smaller excerpt in buffer 2,
5889        // that intersects the old excerpt.
5890        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
5891            multibuffer.remove_excerpts([excerpt_id_3], cx);
5892            multibuffer
5893                .insert_excerpts_after(
5894                    excerpt_id_2,
5895                    buffer_2.clone(),
5896                    [ExcerptRange {
5897                        context: 5..8,
5898                        primary: None,
5899                    }],
5900                    cx,
5901                )
5902                .pop()
5903                .unwrap()
5904        });
5905
5906        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
5907        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
5908        assert_ne!(excerpt_id_5, excerpt_id_3);
5909
5910        // Resolve some anchors from the previous snapshot in the new snapshot.
5911        // The third anchor can't be resolved, since its excerpt has been removed,
5912        // so it resolves to the same position as its predecessor.
5913        let anchors = [
5914            snapshot_2.anchor_before(0),
5915            snapshot_2.anchor_after(2),
5916            snapshot_2.anchor_after(6),
5917            snapshot_2.anchor_after(14),
5918        ];
5919        assert_eq!(
5920            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
5921            &[0, 2, 9, 13]
5922        );
5923
5924        let new_anchors = snapshot_3.refresh_anchors(&anchors);
5925        assert_eq!(
5926            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
5927            &[(0, true), (1, true), (2, true), (3, true)]
5928        );
5929        assert_eq!(
5930            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
5931            &[0, 2, 7, 13]
5932        );
5933    }
5934
5935    #[gpui::test(iterations = 100)]
5936    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
5937        let operations = env::var("OPERATIONS")
5938            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
5939            .unwrap_or(10);
5940
5941        let mut buffers: Vec<Model<Buffer>> = Vec::new();
5942        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5943        let mut excerpt_ids = Vec::<ExcerptId>::new();
5944        let mut expected_excerpts = Vec::<(Model<Buffer>, Range<text::Anchor>)>::new();
5945        let mut anchors = Vec::new();
5946        let mut old_versions = Vec::new();
5947
5948        for _ in 0..operations {
5949            match rng.gen_range(0..100) {
5950                0..=14 if !buffers.is_empty() => {
5951                    let buffer = buffers.choose(&mut rng).unwrap();
5952                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
5953                }
5954                15..=19 if !expected_excerpts.is_empty() => {
5955                    multibuffer.update(cx, |multibuffer, cx| {
5956                        let ids = multibuffer.excerpt_ids();
5957                        let mut excerpts = HashSet::default();
5958                        for _ in 0..rng.gen_range(0..ids.len()) {
5959                            excerpts.extend(ids.choose(&mut rng).copied());
5960                        }
5961
5962                        let line_count = rng.gen_range(0..5);
5963
5964                        let excerpt_ixs = excerpts
5965                            .iter()
5966                            .map(|id| excerpt_ids.iter().position(|i| i == id).unwrap())
5967                            .collect::<Vec<_>>();
5968                        log::info!("Expanding excerpts {excerpt_ixs:?} by {line_count} lines");
5969                        multibuffer.expand_excerpts(
5970                            excerpts.iter().cloned(),
5971                            line_count,
5972                            ExpandExcerptDirection::UpAndDown,
5973                            cx,
5974                        );
5975
5976                        if line_count > 0 {
5977                            for id in excerpts {
5978                                let excerpt_ix = excerpt_ids.iter().position(|&i| i == id).unwrap();
5979                                let (buffer, range) = &mut expected_excerpts[excerpt_ix];
5980                                let snapshot = buffer.read(cx).snapshot();
5981                                let mut point_range = range.to_point(&snapshot);
5982                                point_range.start =
5983                                    Point::new(point_range.start.row.saturating_sub(line_count), 0);
5984                                point_range.end = snapshot.clip_point(
5985                                    Point::new(point_range.end.row + line_count, 0),
5986                                    Bias::Left,
5987                                );
5988                                point_range.end.column = snapshot.line_len(point_range.end.row);
5989                                *range = snapshot.anchor_before(point_range.start)
5990                                    ..snapshot.anchor_after(point_range.end);
5991                            }
5992                        }
5993                    });
5994                }
5995                20..=29 if !expected_excerpts.is_empty() => {
5996                    let mut ids_to_remove = vec![];
5997                    for _ in 0..rng.gen_range(1..=3) {
5998                        if expected_excerpts.is_empty() {
5999                            break;
6000                        }
6001
6002                        let ix = rng.gen_range(0..expected_excerpts.len());
6003                        ids_to_remove.push(excerpt_ids.remove(ix));
6004                        let (buffer, range) = expected_excerpts.remove(ix);
6005                        let buffer = buffer.read(cx);
6006                        log::info!(
6007                            "Removing excerpt {}: {:?}",
6008                            ix,
6009                            buffer
6010                                .text_for_range(range.to_offset(buffer))
6011                                .collect::<String>(),
6012                        );
6013                    }
6014                    let snapshot = multibuffer.read(cx).read(cx);
6015                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
6016                    drop(snapshot);
6017                    multibuffer.update(cx, |multibuffer, cx| {
6018                        multibuffer.remove_excerpts(ids_to_remove, cx)
6019                    });
6020                }
6021                30..=39 if !expected_excerpts.is_empty() => {
6022                    let multibuffer = multibuffer.read(cx).read(cx);
6023                    let offset =
6024                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
6025                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
6026                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
6027                    anchors.push(multibuffer.anchor_at(offset, bias));
6028                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
6029                }
6030                40..=44 if !anchors.is_empty() => {
6031                    let multibuffer = multibuffer.read(cx).read(cx);
6032                    let prev_len = anchors.len();
6033                    anchors = multibuffer
6034                        .refresh_anchors(&anchors)
6035                        .into_iter()
6036                        .map(|a| a.1)
6037                        .collect();
6038
6039                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
6040                    // overshoot its boundaries.
6041                    assert_eq!(anchors.len(), prev_len);
6042                    for anchor in &anchors {
6043                        if anchor.excerpt_id == ExcerptId::min()
6044                            || anchor.excerpt_id == ExcerptId::max()
6045                        {
6046                            continue;
6047                        }
6048
6049                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
6050                        assert_eq!(excerpt.id, anchor.excerpt_id);
6051                        assert!(excerpt.contains(anchor));
6052                    }
6053                }
6054                _ => {
6055                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
6056                        let base_text = util::RandomCharIter::new(&mut rng)
6057                            .take(25)
6058                            .collect::<String>();
6059
6060                        buffers.push(cx.new_model(|cx| Buffer::local(base_text, cx)));
6061                        buffers.last().unwrap()
6062                    } else {
6063                        buffers.choose(&mut rng).unwrap()
6064                    };
6065
6066                    let buffer = buffer_handle.read(cx);
6067                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
6068                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
6069                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
6070                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
6071                    let prev_excerpt_id = excerpt_ids
6072                        .get(prev_excerpt_ix)
6073                        .cloned()
6074                        .unwrap_or_else(ExcerptId::max);
6075                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
6076
6077                    log::info!(
6078                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
6079                        excerpt_ix,
6080                        expected_excerpts.len(),
6081                        buffer_handle.read(cx).remote_id(),
6082                        buffer.text(),
6083                        start_ix..end_ix,
6084                        &buffer.text()[start_ix..end_ix]
6085                    );
6086
6087                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
6088                        multibuffer
6089                            .insert_excerpts_after(
6090                                prev_excerpt_id,
6091                                buffer_handle.clone(),
6092                                [ExcerptRange {
6093                                    context: start_ix..end_ix,
6094                                    primary: None,
6095                                }],
6096                                cx,
6097                            )
6098                            .pop()
6099                            .unwrap()
6100                    });
6101
6102                    excerpt_ids.insert(excerpt_ix, excerpt_id);
6103                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
6104                }
6105            }
6106
6107            if rng.gen_bool(0.3) {
6108                multibuffer.update(cx, |multibuffer, cx| {
6109                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
6110                })
6111            }
6112
6113            let snapshot = multibuffer.read(cx).snapshot(cx);
6114
6115            let mut excerpt_starts = Vec::new();
6116            let mut expected_text = String::new();
6117            let mut expected_buffer_rows = Vec::new();
6118            for (buffer, range) in &expected_excerpts {
6119                let buffer = buffer.read(cx);
6120                let buffer_range = range.to_offset(buffer);
6121
6122                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
6123                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
6124                expected_text.push('\n');
6125
6126                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
6127                    ..=buffer.offset_to_point(buffer_range.end).row;
6128                for row in buffer_row_range {
6129                    expected_buffer_rows.push(Some(row));
6130                }
6131            }
6132            // Remove final trailing newline.
6133            if !expected_excerpts.is_empty() {
6134                expected_text.pop();
6135            }
6136
6137            // Always report one buffer row
6138            if expected_buffer_rows.is_empty() {
6139                expected_buffer_rows.push(Some(0));
6140            }
6141
6142            assert_eq!(snapshot.text(), expected_text);
6143            log::info!("MultiBuffer text: {:?}", expected_text);
6144
6145            assert_eq!(
6146                snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
6147                expected_buffer_rows,
6148            );
6149
6150            for _ in 0..5 {
6151                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
6152                assert_eq!(
6153                    snapshot
6154                        .buffer_rows(MultiBufferRow(start_row as u32))
6155                        .collect::<Vec<_>>(),
6156                    &expected_buffer_rows[start_row..],
6157                    "buffer_rows({})",
6158                    start_row
6159                );
6160            }
6161
6162            assert_eq!(
6163                snapshot.max_buffer_row().0,
6164                expected_buffer_rows.into_iter().flatten().max().unwrap()
6165            );
6166
6167            let mut excerpt_starts = excerpt_starts.into_iter();
6168            for (buffer, range) in &expected_excerpts {
6169                let buffer = buffer.read(cx);
6170                let buffer_id = buffer.remote_id();
6171                let buffer_range = range.to_offset(buffer);
6172                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
6173                let buffer_start_point_utf16 =
6174                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
6175
6176                let excerpt_start = excerpt_starts.next().unwrap();
6177                let mut offset = excerpt_start.len;
6178                let mut buffer_offset = buffer_range.start;
6179                let mut point = excerpt_start.lines;
6180                let mut buffer_point = buffer_start_point;
6181                let mut point_utf16 = excerpt_start.lines_utf16();
6182                let mut buffer_point_utf16 = buffer_start_point_utf16;
6183                for ch in buffer
6184                    .snapshot()
6185                    .chunks(buffer_range.clone(), false)
6186                    .flat_map(|c| c.text.chars())
6187                {
6188                    for _ in 0..ch.len_utf8() {
6189                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
6190                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
6191                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
6192                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
6193                        assert_eq!(
6194                            left_offset,
6195                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
6196                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
6197                            offset,
6198                            buffer_id,
6199                            buffer_offset,
6200                        );
6201                        assert_eq!(
6202                            right_offset,
6203                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
6204                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
6205                            offset,
6206                            buffer_id,
6207                            buffer_offset,
6208                        );
6209
6210                        let left_point = snapshot.clip_point(point, Bias::Left);
6211                        let right_point = snapshot.clip_point(point, Bias::Right);
6212                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
6213                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
6214                        assert_eq!(
6215                            left_point,
6216                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
6217                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
6218                            point,
6219                            buffer_id,
6220                            buffer_point,
6221                        );
6222                        assert_eq!(
6223                            right_point,
6224                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
6225                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
6226                            point,
6227                            buffer_id,
6228                            buffer_point,
6229                        );
6230
6231                        assert_eq!(
6232                            snapshot.point_to_offset(left_point),
6233                            left_offset,
6234                            "point_to_offset({:?})",
6235                            left_point,
6236                        );
6237                        assert_eq!(
6238                            snapshot.offset_to_point(left_offset),
6239                            left_point,
6240                            "offset_to_point({:?})",
6241                            left_offset,
6242                        );
6243
6244                        offset += 1;
6245                        buffer_offset += 1;
6246                        if ch == '\n' {
6247                            point += Point::new(1, 0);
6248                            buffer_point += Point::new(1, 0);
6249                        } else {
6250                            point += Point::new(0, 1);
6251                            buffer_point += Point::new(0, 1);
6252                        }
6253                    }
6254
6255                    for _ in 0..ch.len_utf16() {
6256                        let left_point_utf16 =
6257                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
6258                        let right_point_utf16 =
6259                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
6260                        let buffer_left_point_utf16 =
6261                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
6262                        let buffer_right_point_utf16 =
6263                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
6264                        assert_eq!(
6265                            left_point_utf16,
6266                            excerpt_start.lines_utf16()
6267                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
6268                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
6269                            point_utf16,
6270                            buffer_id,
6271                            buffer_point_utf16,
6272                        );
6273                        assert_eq!(
6274                            right_point_utf16,
6275                            excerpt_start.lines_utf16()
6276                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
6277                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
6278                            point_utf16,
6279                            buffer_id,
6280                            buffer_point_utf16,
6281                        );
6282
6283                        if ch == '\n' {
6284                            point_utf16 += PointUtf16::new(1, 0);
6285                            buffer_point_utf16 += PointUtf16::new(1, 0);
6286                        } else {
6287                            point_utf16 += PointUtf16::new(0, 1);
6288                            buffer_point_utf16 += PointUtf16::new(0, 1);
6289                        }
6290                    }
6291                }
6292            }
6293
6294            for (row, line) in expected_text.split('\n').enumerate() {
6295                assert_eq!(
6296                    snapshot.line_len(MultiBufferRow(row as u32)),
6297                    line.len() as u32,
6298                    "line_len({}).",
6299                    row
6300                );
6301            }
6302
6303            let text_rope = Rope::from(expected_text.as_str());
6304            for _ in 0..10 {
6305                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
6306                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
6307
6308                let text_for_range = snapshot
6309                    .text_for_range(start_ix..end_ix)
6310                    .collect::<String>();
6311                assert_eq!(
6312                    text_for_range,
6313                    &expected_text[start_ix..end_ix],
6314                    "incorrect text for range {:?}",
6315                    start_ix..end_ix
6316                );
6317
6318                let excerpted_buffer_ranges = multibuffer
6319                    .read(cx)
6320                    .range_to_buffer_ranges(start_ix..end_ix, cx);
6321                let excerpted_buffers_text = excerpted_buffer_ranges
6322                    .iter()
6323                    .map(|(buffer, buffer_range, _)| {
6324                        buffer
6325                            .read(cx)
6326                            .text_for_range(buffer_range.clone())
6327                            .collect::<String>()
6328                    })
6329                    .collect::<Vec<_>>()
6330                    .join("\n");
6331                assert_eq!(excerpted_buffers_text, text_for_range);
6332                if !expected_excerpts.is_empty() {
6333                    assert!(!excerpted_buffer_ranges.is_empty());
6334                }
6335
6336                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
6337                assert_eq!(
6338                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
6339                    expected_summary,
6340                    "incorrect summary for range {:?}",
6341                    start_ix..end_ix
6342                );
6343            }
6344
6345            // Anchor resolution
6346            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
6347            assert_eq!(anchors.len(), summaries.len());
6348            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
6349                assert!(resolved_offset <= snapshot.len());
6350                assert_eq!(
6351                    snapshot.summary_for_anchor::<usize>(anchor),
6352                    resolved_offset
6353                );
6354            }
6355
6356            for _ in 0..10 {
6357                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
6358                assert_eq!(
6359                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
6360                    expected_text[..end_ix].chars().rev().collect::<String>(),
6361                );
6362            }
6363
6364            for _ in 0..10 {
6365                let end_ix = rng.gen_range(0..=text_rope.len());
6366                let start_ix = rng.gen_range(0..=end_ix);
6367                assert_eq!(
6368                    snapshot
6369                        .bytes_in_range(start_ix..end_ix)
6370                        .flatten()
6371                        .copied()
6372                        .collect::<Vec<_>>(),
6373                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
6374                    "bytes_in_range({:?})",
6375                    start_ix..end_ix,
6376                );
6377            }
6378        }
6379
6380        let snapshot = multibuffer.read(cx).snapshot(cx);
6381        for (old_snapshot, subscription) in old_versions {
6382            let edits = subscription.consume().into_inner();
6383
6384            log::info!(
6385                "applying subscription edits to old text: {:?}: {:?}",
6386                old_snapshot.text(),
6387                edits,
6388            );
6389
6390            let mut text = old_snapshot.text();
6391            for edit in edits {
6392                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
6393                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
6394            }
6395            assert_eq!(text.to_string(), snapshot.text());
6396        }
6397    }
6398
6399    #[gpui::test]
6400    fn test_history(cx: &mut AppContext) {
6401        let test_settings = SettingsStore::test(cx);
6402        cx.set_global(test_settings);
6403
6404        let buffer_1 = cx.new_model(|cx| Buffer::local("1234", cx));
6405        let buffer_2 = cx.new_model(|cx| Buffer::local("5678", cx));
6406        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6407        let group_interval = multibuffer.read(cx).history.group_interval;
6408        multibuffer.update(cx, |multibuffer, cx| {
6409            multibuffer.push_excerpts(
6410                buffer_1.clone(),
6411                [ExcerptRange {
6412                    context: 0..buffer_1.read(cx).len(),
6413                    primary: None,
6414                }],
6415                cx,
6416            );
6417            multibuffer.push_excerpts(
6418                buffer_2.clone(),
6419                [ExcerptRange {
6420                    context: 0..buffer_2.read(cx).len(),
6421                    primary: None,
6422                }],
6423                cx,
6424            );
6425        });
6426
6427        let mut now = Instant::now();
6428
6429        multibuffer.update(cx, |multibuffer, cx| {
6430            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
6431            multibuffer.edit(
6432                [
6433                    (Point::new(0, 0)..Point::new(0, 0), "A"),
6434                    (Point::new(1, 0)..Point::new(1, 0), "A"),
6435                ],
6436                None,
6437                cx,
6438            );
6439            multibuffer.edit(
6440                [
6441                    (Point::new(0, 1)..Point::new(0, 1), "B"),
6442                    (Point::new(1, 1)..Point::new(1, 1), "B"),
6443                ],
6444                None,
6445                cx,
6446            );
6447            multibuffer.end_transaction_at(now, cx);
6448            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6449
6450            // Verify edited ranges for transaction 1
6451            assert_eq!(
6452                multibuffer.edited_ranges_for_transaction(transaction_1, cx),
6453                &[
6454                    Point::new(0, 0)..Point::new(0, 2),
6455                    Point::new(1, 0)..Point::new(1, 2)
6456                ]
6457            );
6458
6459            // Edit buffer 1 through the multibuffer
6460            now += 2 * group_interval;
6461            multibuffer.start_transaction_at(now, cx);
6462            multibuffer.edit([(2..2, "C")], None, cx);
6463            multibuffer.end_transaction_at(now, cx);
6464            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
6465
6466            // Edit buffer 1 independently
6467            buffer_1.update(cx, |buffer_1, cx| {
6468                buffer_1.start_transaction_at(now);
6469                buffer_1.edit([(3..3, "D")], None, cx);
6470                buffer_1.end_transaction_at(now, cx);
6471
6472                now += 2 * group_interval;
6473                buffer_1.start_transaction_at(now);
6474                buffer_1.edit([(4..4, "E")], None, cx);
6475                buffer_1.end_transaction_at(now, cx);
6476            });
6477            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
6478
6479            // An undo in the multibuffer undoes the multibuffer transaction
6480            // and also any individual buffer edits that have occurred since
6481            // that transaction.
6482            multibuffer.undo(cx);
6483            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6484
6485            multibuffer.undo(cx);
6486            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6487
6488            multibuffer.redo(cx);
6489            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6490
6491            multibuffer.redo(cx);
6492            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
6493
6494            // Undo buffer 2 independently.
6495            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
6496            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
6497
6498            // An undo in the multibuffer undoes the components of the
6499            // the last multibuffer transaction that are not already undone.
6500            multibuffer.undo(cx);
6501            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
6502
6503            multibuffer.undo(cx);
6504            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6505
6506            multibuffer.redo(cx);
6507            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6508
6509            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
6510            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
6511
6512            // Redo stack gets cleared after an edit.
6513            now += 2 * group_interval;
6514            multibuffer.start_transaction_at(now, cx);
6515            multibuffer.edit([(0..0, "X")], None, cx);
6516            multibuffer.end_transaction_at(now, cx);
6517            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6518            multibuffer.redo(cx);
6519            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6520            multibuffer.undo(cx);
6521            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
6522            multibuffer.undo(cx);
6523            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6524
6525            // Transactions can be grouped manually.
6526            multibuffer.redo(cx);
6527            multibuffer.redo(cx);
6528            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6529            multibuffer.group_until_transaction(transaction_1, cx);
6530            multibuffer.undo(cx);
6531            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6532            multibuffer.redo(cx);
6533            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6534        });
6535    }
6536
6537    #[gpui::test]
6538    fn test_excerpts_in_ranges_no_ranges(cx: &mut AppContext) {
6539        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6540        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6541        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6542        multibuffer.update(cx, |multibuffer, cx| {
6543            multibuffer.push_excerpts(
6544                buffer_1.clone(),
6545                [ExcerptRange {
6546                    context: 0..buffer_1.read(cx).len(),
6547                    primary: None,
6548                }],
6549                cx,
6550            );
6551            multibuffer.push_excerpts(
6552                buffer_2.clone(),
6553                [ExcerptRange {
6554                    context: 0..buffer_2.read(cx).len(),
6555                    primary: None,
6556                }],
6557                cx,
6558            );
6559        });
6560
6561        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
6562
6563        let mut excerpts = snapshot.excerpts_in_ranges(iter::from_fn(|| None));
6564
6565        assert!(excerpts.next().is_none());
6566    }
6567
6568    fn validate_excerpts(
6569        actual: &[(ExcerptId, BufferId, Range<Anchor>)],
6570        expected: &Vec<(ExcerptId, BufferId, Range<Anchor>)>,
6571    ) {
6572        assert_eq!(actual.len(), expected.len());
6573
6574        actual
6575            .iter()
6576            .zip(expected)
6577            .map(|(actual, expected)| {
6578                assert_eq!(actual.0, expected.0);
6579                assert_eq!(actual.1, expected.1);
6580                assert_eq!(actual.2.start, expected.2.start);
6581                assert_eq!(actual.2.end, expected.2.end);
6582            })
6583            .collect_vec();
6584    }
6585
6586    fn map_range_from_excerpt(
6587        snapshot: &MultiBufferSnapshot,
6588        excerpt_id: ExcerptId,
6589        excerpt_buffer: &BufferSnapshot,
6590        range: Range<usize>,
6591    ) -> Range<Anchor> {
6592        snapshot
6593            .anchor_in_excerpt(excerpt_id, excerpt_buffer.anchor_before(range.start))
6594            .unwrap()
6595            ..snapshot
6596                .anchor_in_excerpt(excerpt_id, excerpt_buffer.anchor_after(range.end))
6597                .unwrap()
6598    }
6599
6600    fn make_expected_excerpt_info(
6601        snapshot: &MultiBufferSnapshot,
6602        cx: &mut AppContext,
6603        excerpt_id: ExcerptId,
6604        buffer: &Model<Buffer>,
6605        range: Range<usize>,
6606    ) -> (ExcerptId, BufferId, Range<Anchor>) {
6607        (
6608            excerpt_id,
6609            buffer.read(cx).remote_id(),
6610            map_range_from_excerpt(snapshot, excerpt_id, &buffer.read(cx).snapshot(), range),
6611        )
6612    }
6613
6614    #[gpui::test]
6615    fn test_excerpts_in_ranges_range_inside_the_excerpt(cx: &mut AppContext) {
6616        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6617        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6618        let buffer_len = buffer_1.read(cx).len();
6619        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6620        let mut expected_excerpt_id = ExcerptId(0);
6621
6622        multibuffer.update(cx, |multibuffer, cx| {
6623            expected_excerpt_id = multibuffer.push_excerpts(
6624                buffer_1.clone(),
6625                [ExcerptRange {
6626                    context: 0..buffer_1.read(cx).len(),
6627                    primary: None,
6628                }],
6629                cx,
6630            )[0];
6631            multibuffer.push_excerpts(
6632                buffer_2.clone(),
6633                [ExcerptRange {
6634                    context: 0..buffer_2.read(cx).len(),
6635                    primary: None,
6636                }],
6637                cx,
6638            );
6639        });
6640
6641        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
6642
6643        let range = snapshot
6644            .anchor_in_excerpt(expected_excerpt_id, buffer_1.read(cx).anchor_before(1))
6645            .unwrap()
6646            ..snapshot
6647                .anchor_in_excerpt(
6648                    expected_excerpt_id,
6649                    buffer_1.read(cx).anchor_after(buffer_len / 2),
6650                )
6651                .unwrap();
6652
6653        let expected_excerpts = vec![make_expected_excerpt_info(
6654            &snapshot,
6655            cx,
6656            expected_excerpt_id,
6657            &buffer_1,
6658            1..(buffer_len / 2),
6659        )];
6660
6661        let excerpts = snapshot
6662            .excerpts_in_ranges(vec![range.clone()].into_iter())
6663            .map(|(excerpt_id, buffer, actual_range)| {
6664                (
6665                    excerpt_id,
6666                    buffer.remote_id(),
6667                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6668                )
6669            })
6670            .collect_vec();
6671
6672        validate_excerpts(&excerpts, &expected_excerpts);
6673    }
6674
6675    #[gpui::test]
6676    fn test_excerpts_in_ranges_range_crosses_excerpts_boundary(cx: &mut AppContext) {
6677        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6678        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6679        let buffer_len = buffer_1.read(cx).len();
6680        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6681        let mut excerpt_1_id = ExcerptId(0);
6682        let mut excerpt_2_id = ExcerptId(0);
6683
6684        multibuffer.update(cx, |multibuffer, cx| {
6685            excerpt_1_id = multibuffer.push_excerpts(
6686                buffer_1.clone(),
6687                [ExcerptRange {
6688                    context: 0..buffer_1.read(cx).len(),
6689                    primary: None,
6690                }],
6691                cx,
6692            )[0];
6693            excerpt_2_id = multibuffer.push_excerpts(
6694                buffer_2.clone(),
6695                [ExcerptRange {
6696                    context: 0..buffer_2.read(cx).len(),
6697                    primary: None,
6698                }],
6699                cx,
6700            )[0];
6701        });
6702
6703        let snapshot = multibuffer.read(cx).snapshot(cx);
6704
6705        let expected_range = snapshot
6706            .anchor_in_excerpt(
6707                excerpt_1_id,
6708                buffer_1.read(cx).anchor_before(buffer_len / 2),
6709            )
6710            .unwrap()
6711            ..snapshot
6712                .anchor_in_excerpt(excerpt_2_id, buffer_2.read(cx).anchor_after(buffer_len / 2))
6713                .unwrap();
6714
6715        let expected_excerpts = vec![
6716            make_expected_excerpt_info(
6717                &snapshot,
6718                cx,
6719                excerpt_1_id,
6720                &buffer_1,
6721                (buffer_len / 2)..buffer_len,
6722            ),
6723            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, 0..buffer_len / 2),
6724        ];
6725
6726        let excerpts = snapshot
6727            .excerpts_in_ranges(vec![expected_range.clone()].into_iter())
6728            .map(|(excerpt_id, buffer, actual_range)| {
6729                (
6730                    excerpt_id,
6731                    buffer.remote_id(),
6732                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6733                )
6734            })
6735            .collect_vec();
6736
6737        validate_excerpts(&excerpts, &expected_excerpts);
6738    }
6739
6740    #[gpui::test]
6741    fn test_excerpts_in_ranges_range_encloses_excerpt(cx: &mut AppContext) {
6742        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6743        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6744        let buffer_3 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'r'), cx));
6745        let buffer_len = buffer_1.read(cx).len();
6746        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6747        let mut excerpt_1_id = ExcerptId(0);
6748        let mut excerpt_2_id = ExcerptId(0);
6749        let mut excerpt_3_id = ExcerptId(0);
6750
6751        multibuffer.update(cx, |multibuffer, cx| {
6752            excerpt_1_id = multibuffer.push_excerpts(
6753                buffer_1.clone(),
6754                [ExcerptRange {
6755                    context: 0..buffer_1.read(cx).len(),
6756                    primary: None,
6757                }],
6758                cx,
6759            )[0];
6760            excerpt_2_id = multibuffer.push_excerpts(
6761                buffer_2.clone(),
6762                [ExcerptRange {
6763                    context: 0..buffer_2.read(cx).len(),
6764                    primary: None,
6765                }],
6766                cx,
6767            )[0];
6768            excerpt_3_id = multibuffer.push_excerpts(
6769                buffer_3.clone(),
6770                [ExcerptRange {
6771                    context: 0..buffer_3.read(cx).len(),
6772                    primary: None,
6773                }],
6774                cx,
6775            )[0];
6776        });
6777
6778        let snapshot = multibuffer.read(cx).snapshot(cx);
6779
6780        let expected_range = snapshot
6781            .anchor_in_excerpt(
6782                excerpt_1_id,
6783                buffer_1.read(cx).anchor_before(buffer_len / 2),
6784            )
6785            .unwrap()
6786            ..snapshot
6787                .anchor_in_excerpt(excerpt_3_id, buffer_3.read(cx).anchor_after(buffer_len / 2))
6788                .unwrap();
6789
6790        let expected_excerpts = vec![
6791            make_expected_excerpt_info(
6792                &snapshot,
6793                cx,
6794                excerpt_1_id,
6795                &buffer_1,
6796                (buffer_len / 2)..buffer_len,
6797            ),
6798            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, 0..buffer_len),
6799            make_expected_excerpt_info(&snapshot, cx, excerpt_3_id, &buffer_3, 0..buffer_len / 2),
6800        ];
6801
6802        let excerpts = snapshot
6803            .excerpts_in_ranges(vec![expected_range.clone()].into_iter())
6804            .map(|(excerpt_id, buffer, actual_range)| {
6805                (
6806                    excerpt_id,
6807                    buffer.remote_id(),
6808                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6809                )
6810            })
6811            .collect_vec();
6812
6813        validate_excerpts(&excerpts, &expected_excerpts);
6814    }
6815
6816    #[gpui::test]
6817    fn test_excerpts_in_ranges_multiple_ranges(cx: &mut AppContext) {
6818        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6819        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6820        let buffer_len = buffer_1.read(cx).len();
6821        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6822        let mut excerpt_1_id = ExcerptId(0);
6823        let mut excerpt_2_id = ExcerptId(0);
6824
6825        multibuffer.update(cx, |multibuffer, cx| {
6826            excerpt_1_id = multibuffer.push_excerpts(
6827                buffer_1.clone(),
6828                [ExcerptRange {
6829                    context: 0..buffer_1.read(cx).len(),
6830                    primary: None,
6831                }],
6832                cx,
6833            )[0];
6834            excerpt_2_id = multibuffer.push_excerpts(
6835                buffer_2.clone(),
6836                [ExcerptRange {
6837                    context: 0..buffer_2.read(cx).len(),
6838                    primary: None,
6839                }],
6840                cx,
6841            )[0];
6842        });
6843
6844        let snapshot = multibuffer.read(cx).snapshot(cx);
6845
6846        let ranges = vec![
6847            1..(buffer_len / 4),
6848            (buffer_len / 3)..(buffer_len / 2),
6849            (buffer_len / 4 * 3)..(buffer_len),
6850        ];
6851
6852        let expected_excerpts = ranges
6853            .iter()
6854            .map(|range| {
6855                make_expected_excerpt_info(&snapshot, cx, excerpt_1_id, &buffer_1, range.clone())
6856            })
6857            .collect_vec();
6858
6859        let ranges = ranges.into_iter().map(|range| {
6860            map_range_from_excerpt(
6861                &snapshot,
6862                excerpt_1_id,
6863                &buffer_1.read(cx).snapshot(),
6864                range,
6865            )
6866        });
6867
6868        let excerpts = snapshot
6869            .excerpts_in_ranges(ranges)
6870            .map(|(excerpt_id, buffer, actual_range)| {
6871                (
6872                    excerpt_id,
6873                    buffer.remote_id(),
6874                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6875                )
6876            })
6877            .collect_vec();
6878
6879        validate_excerpts(&excerpts, &expected_excerpts);
6880    }
6881
6882    #[gpui::test]
6883    fn test_excerpts_in_ranges_range_ends_at_excerpt_end(cx: &mut AppContext) {
6884        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6885        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6886        let buffer_len = buffer_1.read(cx).len();
6887        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6888        let mut excerpt_1_id = ExcerptId(0);
6889        let mut excerpt_2_id = ExcerptId(0);
6890
6891        multibuffer.update(cx, |multibuffer, cx| {
6892            excerpt_1_id = multibuffer.push_excerpts(
6893                buffer_1.clone(),
6894                [ExcerptRange {
6895                    context: 0..buffer_1.read(cx).len(),
6896                    primary: None,
6897                }],
6898                cx,
6899            )[0];
6900            excerpt_2_id = multibuffer.push_excerpts(
6901                buffer_2.clone(),
6902                [ExcerptRange {
6903                    context: 0..buffer_2.read(cx).len(),
6904                    primary: None,
6905                }],
6906                cx,
6907            )[0];
6908        });
6909
6910        let snapshot = multibuffer.read(cx).snapshot(cx);
6911
6912        let ranges = [0..buffer_len, (buffer_len / 3)..(buffer_len / 2)];
6913
6914        let expected_excerpts = vec![
6915            make_expected_excerpt_info(&snapshot, cx, excerpt_1_id, &buffer_1, ranges[0].clone()),
6916            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, ranges[1].clone()),
6917        ];
6918
6919        let ranges = [
6920            map_range_from_excerpt(
6921                &snapshot,
6922                excerpt_1_id,
6923                &buffer_1.read(cx).snapshot(),
6924                ranges[0].clone(),
6925            ),
6926            map_range_from_excerpt(
6927                &snapshot,
6928                excerpt_2_id,
6929                &buffer_2.read(cx).snapshot(),
6930                ranges[1].clone(),
6931            ),
6932        ];
6933
6934        let excerpts = snapshot
6935            .excerpts_in_ranges(ranges.into_iter())
6936            .map(|(excerpt_id, buffer, actual_range)| {
6937                (
6938                    excerpt_id,
6939                    buffer.remote_id(),
6940                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6941                )
6942            })
6943            .collect_vec();
6944
6945        validate_excerpts(&excerpts, &expected_excerpts);
6946    }
6947
6948    #[gpui::test]
6949    fn test_split_ranges(cx: &mut AppContext) {
6950        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6951        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6952        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6953        multibuffer.update(cx, |multibuffer, cx| {
6954            multibuffer.push_excerpts(
6955                buffer_1.clone(),
6956                [ExcerptRange {
6957                    context: 0..buffer_1.read(cx).len(),
6958                    primary: None,
6959                }],
6960                cx,
6961            );
6962            multibuffer.push_excerpts(
6963                buffer_2.clone(),
6964                [ExcerptRange {
6965                    context: 0..buffer_2.read(cx).len(),
6966                    primary: None,
6967                }],
6968                cx,
6969            );
6970        });
6971
6972        let snapshot = multibuffer.read(cx).snapshot(cx);
6973
6974        let buffer_1_len = buffer_1.read(cx).len();
6975        let buffer_2_len = buffer_2.read(cx).len();
6976        let buffer_1_midpoint = buffer_1_len / 2;
6977        let buffer_2_start = buffer_1_len + '\n'.len_utf8();
6978        let buffer_2_midpoint = buffer_2_start + buffer_2_len / 2;
6979        let total_len = buffer_2_start + buffer_2_len;
6980
6981        let input_ranges = [
6982            0..buffer_1_midpoint,
6983            buffer_1_midpoint..buffer_2_midpoint,
6984            buffer_2_midpoint..total_len,
6985        ]
6986        .map(|range| snapshot.anchor_before(range.start)..snapshot.anchor_after(range.end));
6987
6988        let actual_ranges = snapshot
6989            .split_ranges(input_ranges.into_iter())
6990            .map(|range| range.to_offset(&snapshot))
6991            .collect::<Vec<_>>();
6992
6993        let expected_ranges = vec![
6994            0..buffer_1_midpoint,
6995            buffer_1_midpoint..buffer_1_len,
6996            buffer_2_start..buffer_2_midpoint,
6997            buffer_2_midpoint..total_len,
6998        ];
6999
7000        assert_eq!(actual_ranges, expected_ranges);
7001    }
7002
7003    #[gpui::test]
7004    fn test_split_ranges_single_range_spanning_three_excerpts(cx: &mut AppContext) {
7005        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
7006        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
7007        let buffer_3 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'm'), cx));
7008        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
7009        multibuffer.update(cx, |multibuffer, cx| {
7010            multibuffer.push_excerpts(
7011                buffer_1.clone(),
7012                [ExcerptRange {
7013                    context: 0..buffer_1.read(cx).len(),
7014                    primary: None,
7015                }],
7016                cx,
7017            );
7018            multibuffer.push_excerpts(
7019                buffer_2.clone(),
7020                [ExcerptRange {
7021                    context: 0..buffer_2.read(cx).len(),
7022                    primary: None,
7023                }],
7024                cx,
7025            );
7026            multibuffer.push_excerpts(
7027                buffer_3.clone(),
7028                [ExcerptRange {
7029                    context: 0..buffer_3.read(cx).len(),
7030                    primary: None,
7031                }],
7032                cx,
7033            );
7034        });
7035
7036        let snapshot = multibuffer.read(cx).snapshot(cx);
7037
7038        let buffer_1_len = buffer_1.read(cx).len();
7039        let buffer_2_len = buffer_2.read(cx).len();
7040        let buffer_3_len = buffer_3.read(cx).len();
7041        let buffer_2_start = buffer_1_len + '\n'.len_utf8();
7042        let buffer_3_start = buffer_2_start + buffer_2_len + '\n'.len_utf8();
7043        let buffer_1_midpoint = buffer_1_len / 2;
7044        let buffer_3_midpoint = buffer_3_start + buffer_3_len / 2;
7045
7046        let input_range =
7047            snapshot.anchor_before(buffer_1_midpoint)..snapshot.anchor_after(buffer_3_midpoint);
7048
7049        let actual_ranges = snapshot
7050            .split_ranges(std::iter::once(input_range))
7051            .map(|range| range.to_offset(&snapshot))
7052            .collect::<Vec<_>>();
7053
7054        let expected_ranges = vec![
7055            buffer_1_midpoint..buffer_1_len,
7056            buffer_2_start..buffer_2_start + buffer_2_len,
7057            buffer_3_start..buffer_3_midpoint,
7058        ];
7059
7060        assert_eq!(actual_ranges, expected_ranges);
7061    }
7062}