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