multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt, Offset};
   4use anyhow::{anyhow, Result};
   5use clock::ReplicaId;
   6use collections::{BTreeMap, Bound, HashMap, HashSet};
   7use futures::{channel::mpsc, SinkExt};
   8use gpui::{AppContext, EntityId, EventEmitter, Model, ModelContext, Task};
   9use itertools::Itertools;
  10use language::{
  11    language_settings::{language_settings, LanguageSettings},
  12    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharClassifier,
  13    CharKind, Chunk, CursorShape, DiagnosticEntry, File, IndentGuide, IndentSize, Language,
  14    LanguageScope, OffsetRangeExt, OffsetUtf16, Outline, OutlineItem, Point, PointUtf16, Selection,
  15    TextDimension, ToOffset as _, ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _,
  16    TransactionId, Unclipped,
  17};
  18use smallvec::SmallVec;
  19use std::{
  20    any::type_name,
  21    borrow::Cow,
  22    cell::{Ref, RefCell},
  23    cmp, fmt,
  24    future::Future,
  25    io,
  26    iter::{self, FromIterator},
  27    mem,
  28    ops::{Range, RangeBounds, Sub},
  29    str,
  30    sync::Arc,
  31    time::{Duration, Instant},
  32};
  33use sum_tree::{Bias, Cursor, SumTree};
  34use text::{
  35    locator::Locator,
  36    subscription::{Subscription, Topic},
  37    BufferId, Edit, TextSummary,
  38};
  39use theme::SyntaxTheme;
  40
  41use util::post_inc;
  42
  43#[cfg(any(test, feature = "test-support"))]
  44use gpui::Context;
  45
  46const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  47
  48#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  49pub struct ExcerptId(usize);
  50
  51impl From<ExcerptId> for EntityId {
  52    fn from(id: ExcerptId) -> Self {
  53        EntityId::from(id.0 as u64)
  54    }
  55}
  56
  57/// One or more [`Buffers`](Buffer) being edited in a single view.
  58///
  59/// See <https://zed.dev/features#multi-buffers>
  60pub struct MultiBuffer {
  61    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  62    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  63    snapshot: RefCell<MultiBufferSnapshot>,
  64    /// Contains the state of the buffers being edited
  65    buffers: RefCell<HashMap<BufferId, BufferState>>,
  66    subscriptions: Topic,
  67    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  68    singleton: bool,
  69    history: History,
  70    title: Option<String>,
  71    capability: Capability,
  72}
  73
  74#[derive(Clone, Debug, PartialEq, Eq)]
  75pub enum Event {
  76    ExcerptsAdded {
  77        buffer: Model<Buffer>,
  78        predecessor: ExcerptId,
  79        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  80    },
  81    ExcerptsRemoved {
  82        ids: Vec<ExcerptId>,
  83    },
  84    ExcerptsExpanded {
  85        ids: Vec<ExcerptId>,
  86    },
  87    ExcerptsEdited {
  88        ids: Vec<ExcerptId>,
  89    },
  90    Edited {
  91        singleton_buffer_edited: bool,
  92    },
  93    TransactionUndone {
  94        transaction_id: TransactionId,
  95    },
  96    Reloaded,
  97    ReloadNeeded,
  98    DiffBaseChanged,
  99    DiffUpdated {
 100        buffer: Model<Buffer>,
 101    },
 102    LanguageChanged(BufferId),
 103    CapabilityChanged,
 104    Reparsed(BufferId),
 105    Saved,
 106    FileHandleChanged,
 107    Closed,
 108    Discarded,
 109    DirtyChanged,
 110    DiagnosticsUpdated,
 111}
 112
 113/// A diff hunk, representing a range of consequent lines in a multibuffer.
 114#[derive(Debug, Clone, PartialEq, Eq)]
 115pub struct MultiBufferDiffHunk {
 116    /// The row range in the multibuffer where this diff hunk appears.
 117    pub row_range: Range<MultiBufferRow>,
 118    /// The buffer ID that this hunk belongs to.
 119    pub buffer_id: BufferId,
 120    /// The range of the underlying buffer that this hunk corresponds to.
 121    pub buffer_range: Range<text::Anchor>,
 122    /// The range within the buffer's diff base that this hunk corresponds to.
 123    pub diff_base_byte_range: Range<usize>,
 124}
 125
 126pub type MultiBufferPoint = Point;
 127
 128#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, serde::Deserialize)]
 129#[serde(transparent)]
 130pub struct MultiBufferRow(pub u32);
 131
 132impl MultiBufferRow {
 133    pub const MIN: Self = Self(0);
 134    pub const MAX: Self = Self(u32::MAX);
 135}
 136
 137#[derive(Clone)]
 138struct History {
 139    next_transaction_id: TransactionId,
 140    undo_stack: Vec<Transaction>,
 141    redo_stack: Vec<Transaction>,
 142    transaction_depth: usize,
 143    group_interval: Duration,
 144}
 145
 146#[derive(Clone)]
 147struct Transaction {
 148    id: TransactionId,
 149    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 150    first_edit_at: Instant,
 151    last_edit_at: Instant,
 152    suppress_grouping: bool,
 153}
 154
 155pub trait ToOffset: 'static + fmt::Debug {
 156    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 157}
 158
 159pub trait ToOffsetUtf16: 'static + fmt::Debug {
 160    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 161}
 162
 163pub trait ToPoint: 'static + fmt::Debug {
 164    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 165}
 166
 167pub trait ToPointUtf16: 'static + fmt::Debug {
 168    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 169}
 170
 171struct BufferState {
 172    buffer: Model<Buffer>,
 173    last_version: clock::Global,
 174    last_non_text_state_update_count: usize,
 175    excerpts: Vec<Locator>,
 176    _subscriptions: [gpui::Subscription; 2],
 177}
 178
 179/// The contents of a [`MultiBuffer`] at a single point in time.
 180#[derive(Clone, Default)]
 181pub struct MultiBufferSnapshot {
 182    singleton: bool,
 183    excerpts: SumTree<Excerpt>,
 184    excerpt_ids: SumTree<ExcerptIdMapping>,
 185    trailing_excerpt_update_count: usize,
 186    non_text_state_update_count: usize,
 187    edit_count: usize,
 188    is_dirty: bool,
 189    has_conflict: bool,
 190    show_headers: bool,
 191}
 192
 193#[derive(Clone)]
 194pub struct ExcerptInfo {
 195    pub id: ExcerptId,
 196    pub buffer: BufferSnapshot,
 197    pub buffer_id: BufferId,
 198    pub range: ExcerptRange<text::Anchor>,
 199}
 200
 201impl std::fmt::Debug for ExcerptInfo {
 202    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 203        f.debug_struct(type_name::<Self>())
 204            .field("id", &self.id)
 205            .field("buffer_id", &self.buffer_id)
 206            .field("path", &self.buffer.file().map(|f| f.path()))
 207            .field("range", &self.range)
 208            .finish()
 209    }
 210}
 211
 212/// A boundary between [`Excerpt`]s in a [`MultiBuffer`]
 213#[derive(Debug)]
 214pub struct ExcerptBoundary {
 215    pub prev: Option<ExcerptInfo>,
 216    pub next: Option<ExcerptInfo>,
 217    /// The row in the `MultiBuffer` where the boundary is located
 218    pub row: MultiBufferRow,
 219}
 220
 221impl ExcerptBoundary {
 222    pub fn starts_new_buffer(&self) -> bool {
 223        match (self.prev.as_ref(), self.next.as_ref()) {
 224            (None, _) => true,
 225            (Some(_), None) => false,
 226            (Some(prev), Some(next)) => prev.buffer_id != next.buffer_id,
 227        }
 228    }
 229}
 230
 231/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 232#[derive(Clone)]
 233struct Excerpt {
 234    /// The unique identifier for this excerpt
 235    id: ExcerptId,
 236    /// The location of the excerpt in the [`MultiBuffer`]
 237    locator: Locator,
 238    /// The buffer being excerpted
 239    buffer_id: BufferId,
 240    /// A snapshot of the buffer being excerpted
 241    buffer: BufferSnapshot,
 242    /// The range of the buffer to be shown in the excerpt
 243    range: ExcerptRange<text::Anchor>,
 244    /// The last row in the excerpted slice of the buffer
 245    max_buffer_row: BufferRow,
 246    /// A summary of the text in the excerpt
 247    text_summary: TextSummary,
 248    has_trailing_newline: bool,
 249}
 250
 251/// A public view into an [`Excerpt`] in a [`MultiBuffer`].
 252///
 253/// Contains methods for getting the [`Buffer`] of the excerpt,
 254/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 255#[derive(Clone)]
 256pub struct MultiBufferExcerpt<'a> {
 257    excerpt: &'a Excerpt,
 258    excerpt_offset: usize,
 259}
 260
 261#[derive(Clone, Debug)]
 262struct ExcerptIdMapping {
 263    id: ExcerptId,
 264    locator: Locator,
 265}
 266
 267/// A range of text from a single [`Buffer`], to be shown as an [`Excerpt`].
 268/// These ranges are relative to the buffer itself
 269#[derive(Clone, Debug, Eq, PartialEq)]
 270pub struct ExcerptRange<T> {
 271    /// The full range of text to be shown in the excerpt.
 272    pub context: Range<T>,
 273    /// The primary range of text to be highlighted in the excerpt.
 274    /// In a multi-buffer search, this would be the text that matched the search
 275    pub primary: Option<Range<T>>,
 276}
 277
 278#[derive(Clone, Debug, Default)]
 279pub struct ExcerptSummary {
 280    excerpt_id: ExcerptId,
 281    /// The location of the last [`Excerpt`] being summarized
 282    excerpt_locator: Locator,
 283    /// The maximum row of the [`Excerpt`]s being summarized
 284    max_buffer_row: MultiBufferRow,
 285    text: TextSummary,
 286}
 287
 288#[derive(Clone)]
 289pub struct MultiBufferRows<'a> {
 290    buffer_row_range: Range<u32>,
 291    excerpts: Cursor<'a, Excerpt, Point>,
 292}
 293
 294pub struct MultiBufferChunks<'a> {
 295    range: Range<usize>,
 296    excerpts: Cursor<'a, Excerpt, usize>,
 297    excerpt_chunks: Option<ExcerptChunks<'a>>,
 298    language_aware: bool,
 299}
 300
 301pub struct MultiBufferBytes<'a> {
 302    range: Range<usize>,
 303    excerpts: Cursor<'a, Excerpt, usize>,
 304    excerpt_bytes: Option<ExcerptBytes<'a>>,
 305    chunk: &'a [u8],
 306}
 307
 308pub struct ReversedMultiBufferBytes<'a> {
 309    range: Range<usize>,
 310    excerpts: Cursor<'a, Excerpt, usize>,
 311    excerpt_bytes: Option<ExcerptBytes<'a>>,
 312    chunk: &'a [u8],
 313}
 314
 315struct ExcerptChunks<'a> {
 316    excerpt_id: ExcerptId,
 317    content_chunks: BufferChunks<'a>,
 318    footer_height: usize,
 319}
 320
 321struct ExcerptBytes<'a> {
 322    content_bytes: text::Bytes<'a>,
 323    padding_height: usize,
 324    reversed: bool,
 325}
 326
 327#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 328pub enum ExpandExcerptDirection {
 329    Up,
 330    Down,
 331    UpAndDown,
 332}
 333
 334impl ExpandExcerptDirection {
 335    pub fn should_expand_up(&self) -> bool {
 336        match self {
 337            ExpandExcerptDirection::Up => true,
 338            ExpandExcerptDirection::Down => false,
 339            ExpandExcerptDirection::UpAndDown => true,
 340        }
 341    }
 342
 343    pub fn should_expand_down(&self) -> bool {
 344        match self {
 345            ExpandExcerptDirection::Up => false,
 346            ExpandExcerptDirection::Down => true,
 347            ExpandExcerptDirection::UpAndDown => true,
 348        }
 349    }
 350}
 351
 352#[derive(Clone, Debug, PartialEq)]
 353pub struct MultiBufferIndentGuide {
 354    pub multibuffer_row_range: Range<MultiBufferRow>,
 355    pub buffer: IndentGuide,
 356}
 357
 358impl std::ops::Deref for MultiBufferIndentGuide {
 359    type Target = IndentGuide;
 360
 361    fn deref(&self) -> &Self::Target {
 362        &self.buffer
 363    }
 364}
 365
 366impl MultiBuffer {
 367    pub fn new(capability: Capability) -> Self {
 368        Self {
 369            snapshot: RefCell::new(MultiBufferSnapshot {
 370                show_headers: true,
 371                ..MultiBufferSnapshot::default()
 372            }),
 373            buffers: RefCell::default(),
 374            subscriptions: Topic::default(),
 375            singleton: false,
 376            capability,
 377            title: None,
 378            history: History {
 379                next_transaction_id: clock::Lamport::default(),
 380                undo_stack: Vec::new(),
 381                redo_stack: Vec::new(),
 382                transaction_depth: 0,
 383                group_interval: Duration::from_millis(300),
 384            },
 385        }
 386    }
 387
 388    pub fn without_headers(capability: Capability) -> Self {
 389        Self {
 390            snapshot: Default::default(),
 391            buffers: Default::default(),
 392            subscriptions: Default::default(),
 393            singleton: false,
 394            capability,
 395            history: History {
 396                next_transaction_id: Default::default(),
 397                undo_stack: Default::default(),
 398                redo_stack: Default::default(),
 399                transaction_depth: 0,
 400                group_interval: Duration::from_millis(300),
 401            },
 402            title: Default::default(),
 403        }
 404    }
 405
 406    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 407        let mut buffers = HashMap::default();
 408        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 409            buffers.insert(
 410                *buffer_id,
 411                BufferState {
 412                    buffer: buffer_state.buffer.clone(),
 413                    last_version: buffer_state.last_version.clone(),
 414                    last_non_text_state_update_count: buffer_state.last_non_text_state_update_count,
 415                    excerpts: buffer_state.excerpts.clone(),
 416                    _subscriptions: [
 417                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 418                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 419                    ],
 420                },
 421            );
 422        }
 423        Self {
 424            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 425            buffers: RefCell::new(buffers),
 426            subscriptions: Default::default(),
 427            singleton: self.singleton,
 428            capability: self.capability,
 429            history: self.history.clone(),
 430            title: self.title.clone(),
 431        }
 432    }
 433
 434    pub fn with_title(mut self, title: String) -> Self {
 435        self.title = Some(title);
 436        self
 437    }
 438
 439    pub fn read_only(&self) -> bool {
 440        self.capability == Capability::ReadOnly
 441    }
 442
 443    pub fn singleton(buffer: Model<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 444        let mut this = Self::new(buffer.read(cx).capability());
 445        this.singleton = true;
 446        this.push_excerpts(
 447            buffer,
 448            [ExcerptRange {
 449                context: text::Anchor::MIN..text::Anchor::MAX,
 450                primary: None,
 451            }],
 452            cx,
 453        );
 454        this.snapshot.borrow_mut().singleton = true;
 455        this
 456    }
 457
 458    /// Returns an up-to-date snapshot of the MultiBuffer.
 459    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 460        self.sync(cx);
 461        self.snapshot.borrow().clone()
 462    }
 463
 464    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 465        self.sync(cx);
 466        self.snapshot.borrow()
 467    }
 468
 469    pub fn as_singleton(&self) -> Option<Model<Buffer>> {
 470        if self.singleton {
 471            return Some(
 472                self.buffers
 473                    .borrow()
 474                    .values()
 475                    .next()
 476                    .unwrap()
 477                    .buffer
 478                    .clone(),
 479            );
 480        } else {
 481            None
 482        }
 483    }
 484
 485    pub fn is_singleton(&self) -> bool {
 486        self.singleton
 487    }
 488
 489    pub fn subscribe(&mut self) -> Subscription {
 490        self.subscriptions.subscribe()
 491    }
 492
 493    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 494        self.read(cx).is_dirty()
 495    }
 496
 497    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 498        self.read(cx).has_conflict()
 499    }
 500
 501    // The `is_empty` signature doesn't match what clippy expects
 502    #[allow(clippy::len_without_is_empty)]
 503    pub fn len(&self, cx: &AppContext) -> usize {
 504        self.read(cx).len()
 505    }
 506
 507    pub fn is_empty(&self, cx: &AppContext) -> bool {
 508        self.len(cx) != 0
 509    }
 510
 511    pub fn symbols_containing<T: ToOffset>(
 512        &self,
 513        offset: T,
 514        theme: Option<&SyntaxTheme>,
 515        cx: &AppContext,
 516    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 517        self.read(cx).symbols_containing(offset, theme)
 518    }
 519
 520    pub fn edit<I, S, T>(
 521        &self,
 522        edits: I,
 523        mut autoindent_mode: Option<AutoindentMode>,
 524        cx: &mut ModelContext<Self>,
 525    ) where
 526        I: IntoIterator<Item = (Range<S>, T)>,
 527        S: ToOffset,
 528        T: Into<Arc<str>>,
 529    {
 530        if self.read_only() {
 531            return;
 532        }
 533        if self.buffers.borrow().is_empty() {
 534            return;
 535        }
 536
 537        let snapshot = self.read(cx);
 538        let edits = edits.into_iter().map(|(range, new_text)| {
 539            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 540            if range.start > range.end {
 541                mem::swap(&mut range.start, &mut range.end);
 542            }
 543            (range, new_text)
 544        });
 545
 546        if let Some(buffer) = self.as_singleton() {
 547            buffer.update(cx, |buffer, cx| {
 548                buffer.edit(edits, autoindent_mode, cx);
 549            });
 550            cx.emit(Event::ExcerptsEdited {
 551                ids: self.excerpt_ids(),
 552            });
 553            return;
 554        }
 555
 556        let original_indent_columns = match &mut autoindent_mode {
 557            Some(AutoindentMode::Block {
 558                original_indent_columns,
 559            }) => mem::take(original_indent_columns),
 560            _ => Default::default(),
 561        };
 562
 563        struct BufferEdit {
 564            range: Range<usize>,
 565            new_text: Arc<str>,
 566            is_insertion: bool,
 567            original_indent_column: u32,
 568        }
 569        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 570        let mut edited_excerpt_ids = Vec::new();
 571        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
 572        for (ix, (range, new_text)) in edits.enumerate() {
 573            let new_text: Arc<str> = new_text.into();
 574            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 575            cursor.seek(&range.start, Bias::Right, &());
 576            if cursor.item().is_none() && range.start == *cursor.start() {
 577                cursor.prev(&());
 578            }
 579            let start_excerpt = cursor.item().expect("start offset out of bounds");
 580            let start_overshoot = range.start - cursor.start();
 581            let buffer_start = start_excerpt
 582                .range
 583                .context
 584                .start
 585                .to_offset(&start_excerpt.buffer)
 586                + start_overshoot;
 587            edited_excerpt_ids.push(start_excerpt.id);
 588
 589            cursor.seek(&range.end, Bias::Right, &());
 590            if cursor.item().is_none() && range.end == *cursor.start() {
 591                cursor.prev(&());
 592            }
 593            let end_excerpt = cursor.item().expect("end offset out of bounds");
 594            let end_overshoot = range.end - cursor.start();
 595            let buffer_end = end_excerpt
 596                .range
 597                .context
 598                .start
 599                .to_offset(&end_excerpt.buffer)
 600                + end_overshoot;
 601
 602            if start_excerpt.id == end_excerpt.id {
 603                buffer_edits
 604                    .entry(start_excerpt.buffer_id)
 605                    .or_default()
 606                    .push(BufferEdit {
 607                        range: buffer_start..buffer_end,
 608                        new_text,
 609                        is_insertion: true,
 610                        original_indent_column,
 611                    });
 612            } else {
 613                edited_excerpt_ids.push(end_excerpt.id);
 614                let start_excerpt_range = buffer_start
 615                    ..start_excerpt
 616                        .range
 617                        .context
 618                        .end
 619                        .to_offset(&start_excerpt.buffer);
 620                let end_excerpt_range = end_excerpt
 621                    .range
 622                    .context
 623                    .start
 624                    .to_offset(&end_excerpt.buffer)
 625                    ..buffer_end;
 626                buffer_edits
 627                    .entry(start_excerpt.buffer_id)
 628                    .or_default()
 629                    .push(BufferEdit {
 630                        range: start_excerpt_range,
 631                        new_text: new_text.clone(),
 632                        is_insertion: true,
 633                        original_indent_column,
 634                    });
 635                buffer_edits
 636                    .entry(end_excerpt.buffer_id)
 637                    .or_default()
 638                    .push(BufferEdit {
 639                        range: end_excerpt_range,
 640                        new_text: new_text.clone(),
 641                        is_insertion: false,
 642                        original_indent_column,
 643                    });
 644
 645                cursor.seek(&range.start, Bias::Right, &());
 646                cursor.next(&());
 647                while let Some(excerpt) = cursor.item() {
 648                    if excerpt.id == end_excerpt.id {
 649                        break;
 650                    }
 651                    buffer_edits
 652                        .entry(excerpt.buffer_id)
 653                        .or_default()
 654                        .push(BufferEdit {
 655                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 656                            new_text: new_text.clone(),
 657                            is_insertion: false,
 658                            original_indent_column,
 659                        });
 660                    edited_excerpt_ids.push(excerpt.id);
 661                    cursor.next(&());
 662                }
 663            }
 664        }
 665
 666        drop(cursor);
 667        drop(snapshot);
 668        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 669        fn tail(
 670            this: &MultiBuffer,
 671            buffer_edits: HashMap<BufferId, Vec<BufferEdit>>,
 672            autoindent_mode: Option<AutoindentMode>,
 673            edited_excerpt_ids: Vec<ExcerptId>,
 674            cx: &mut ModelContext<MultiBuffer>,
 675        ) {
 676            for (buffer_id, mut edits) in buffer_edits {
 677                edits.sort_unstable_by_key(|edit| edit.range.start);
 678                this.buffers.borrow()[&buffer_id]
 679                    .buffer
 680                    .update(cx, |buffer, cx| {
 681                        let mut edits = edits.into_iter().peekable();
 682                        let mut insertions = Vec::new();
 683                        let mut original_indent_columns = Vec::new();
 684                        let mut deletions = Vec::new();
 685                        let empty_str: Arc<str> = Arc::default();
 686                        while let Some(BufferEdit {
 687                            mut range,
 688                            new_text,
 689                            mut is_insertion,
 690                            original_indent_column,
 691                        }) = edits.next()
 692                        {
 693                            while let Some(BufferEdit {
 694                                range: next_range,
 695                                is_insertion: next_is_insertion,
 696                                ..
 697                            }) = edits.peek()
 698                            {
 699                                if range.end >= next_range.start {
 700                                    range.end = cmp::max(next_range.end, range.end);
 701                                    is_insertion |= *next_is_insertion;
 702                                    edits.next();
 703                                } else {
 704                                    break;
 705                                }
 706                            }
 707
 708                            if is_insertion {
 709                                original_indent_columns.push(original_indent_column);
 710                                insertions.push((
 711                                    buffer.anchor_before(range.start)
 712                                        ..buffer.anchor_before(range.end),
 713                                    new_text.clone(),
 714                                ));
 715                            } else if !range.is_empty() {
 716                                deletions.push((
 717                                    buffer.anchor_before(range.start)
 718                                        ..buffer.anchor_before(range.end),
 719                                    empty_str.clone(),
 720                                ));
 721                            }
 722                        }
 723
 724                        let deletion_autoindent_mode =
 725                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 726                                Some(AutoindentMode::Block {
 727                                    original_indent_columns: Default::default(),
 728                                })
 729                            } else {
 730                                autoindent_mode.clone()
 731                            };
 732                        let insertion_autoindent_mode =
 733                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 734                                Some(AutoindentMode::Block {
 735                                    original_indent_columns,
 736                                })
 737                            } else {
 738                                autoindent_mode.clone()
 739                            };
 740
 741                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 742                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 743                    })
 744            }
 745
 746            cx.emit(Event::ExcerptsEdited {
 747                ids: edited_excerpt_ids,
 748            });
 749        }
 750        tail(self, buffer_edits, autoindent_mode, edited_excerpt_ids, cx);
 751    }
 752
 753    // Inserts newlines at the given position to create an empty line, returning the start of the new line.
 754    // You can also request the insertion of empty lines above and below the line starting at the returned point.
 755    // Panics if the given position is invalid.
 756    pub fn insert_empty_line(
 757        &mut self,
 758        position: impl ToPoint,
 759        space_above: bool,
 760        space_below: bool,
 761        cx: &mut ModelContext<Self>,
 762    ) -> Point {
 763        let multibuffer_point = position.to_point(&self.read(cx));
 764        if let Some(buffer) = self.as_singleton() {
 765            buffer.update(cx, |buffer, cx| {
 766                buffer.insert_empty_line(multibuffer_point, space_above, space_below, cx)
 767            })
 768        } else {
 769            let (buffer, buffer_point, _) =
 770                self.point_to_buffer_point(multibuffer_point, cx).unwrap();
 771            self.start_transaction(cx);
 772            let empty_line_start = buffer.update(cx, |buffer, cx| {
 773                buffer.insert_empty_line(buffer_point, space_above, space_below, cx)
 774            });
 775            self.end_transaction(cx);
 776            multibuffer_point + (empty_line_start - buffer_point)
 777        }
 778    }
 779
 780    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 781        self.start_transaction_at(Instant::now(), cx)
 782    }
 783
 784    pub fn start_transaction_at(
 785        &mut self,
 786        now: Instant,
 787        cx: &mut ModelContext<Self>,
 788    ) -> Option<TransactionId> {
 789        if let Some(buffer) = self.as_singleton() {
 790            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 791        }
 792
 793        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 794            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 795        }
 796        self.history.start_transaction(now)
 797    }
 798
 799    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 800        self.end_transaction_at(Instant::now(), cx)
 801    }
 802
 803    pub fn end_transaction_at(
 804        &mut self,
 805        now: Instant,
 806        cx: &mut ModelContext<Self>,
 807    ) -> Option<TransactionId> {
 808        if let Some(buffer) = self.as_singleton() {
 809            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 810        }
 811
 812        let mut buffer_transactions = HashMap::default();
 813        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 814            if let Some(transaction_id) =
 815                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 816            {
 817                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 818            }
 819        }
 820
 821        if self.history.end_transaction(now, buffer_transactions) {
 822            let transaction_id = self.history.group().unwrap();
 823            Some(transaction_id)
 824        } else {
 825            None
 826        }
 827    }
 828
 829    pub fn edited_ranges_for_transaction<D>(
 830        &self,
 831        transaction_id: TransactionId,
 832        cx: &AppContext,
 833    ) -> Vec<Range<D>>
 834    where
 835        D: TextDimension + Ord + Sub<D, Output = D>,
 836    {
 837        if let Some(buffer) = self.as_singleton() {
 838            return buffer
 839                .read(cx)
 840                .edited_ranges_for_transaction_id(transaction_id)
 841                .collect::<Vec<_>>();
 842        }
 843
 844        let Some(transaction) = self.history.transaction(transaction_id) else {
 845            return Vec::new();
 846        };
 847
 848        let mut ranges = Vec::new();
 849        let snapshot = self.read(cx);
 850        let buffers = self.buffers.borrow();
 851        let mut cursor = snapshot.excerpts.cursor::<ExcerptSummary>(&());
 852
 853        for (buffer_id, buffer_transaction) in &transaction.buffer_transactions {
 854            let Some(buffer_state) = buffers.get(buffer_id) else {
 855                continue;
 856            };
 857
 858            let buffer = buffer_state.buffer.read(cx);
 859            for range in buffer.edited_ranges_for_transaction_id::<D>(*buffer_transaction) {
 860                for excerpt_id in &buffer_state.excerpts {
 861                    cursor.seek(excerpt_id, Bias::Left, &());
 862                    if let Some(excerpt) = cursor.item() {
 863                        if excerpt.locator == *excerpt_id {
 864                            let excerpt_buffer_start =
 865                                excerpt.range.context.start.summary::<D>(buffer);
 866                            let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(buffer);
 867                            let excerpt_range = excerpt_buffer_start.clone()..excerpt_buffer_end;
 868                            if excerpt_range.contains(&range.start)
 869                                && excerpt_range.contains(&range.end)
 870                            {
 871                                let excerpt_start = D::from_text_summary(&cursor.start().text);
 872
 873                                let mut start = excerpt_start.clone();
 874                                start.add_assign(&(range.start - excerpt_buffer_start.clone()));
 875                                let mut end = excerpt_start;
 876                                end.add_assign(&(range.end - excerpt_buffer_start));
 877
 878                                ranges.push(start..end);
 879                                break;
 880                            }
 881                        }
 882                    }
 883                }
 884            }
 885        }
 886
 887        ranges.sort_by_key(|range| range.start.clone());
 888        ranges
 889    }
 890
 891    pub fn merge_transactions(
 892        &mut self,
 893        transaction: TransactionId,
 894        destination: TransactionId,
 895        cx: &mut ModelContext<Self>,
 896    ) {
 897        if let Some(buffer) = self.as_singleton() {
 898            buffer.update(cx, |buffer, _| {
 899                buffer.merge_transactions(transaction, destination)
 900            });
 901        } else if let Some(transaction) = self.history.forget(transaction) {
 902            if let Some(destination) = self.history.transaction_mut(destination) {
 903                for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
 904                    if let Some(destination_buffer_transaction_id) =
 905                        destination.buffer_transactions.get(&buffer_id)
 906                    {
 907                        if let Some(state) = self.buffers.borrow().get(&buffer_id) {
 908                            state.buffer.update(cx, |buffer, _| {
 909                                buffer.merge_transactions(
 910                                    buffer_transaction_id,
 911                                    *destination_buffer_transaction_id,
 912                                )
 913                            });
 914                        }
 915                    } else {
 916                        destination
 917                            .buffer_transactions
 918                            .insert(buffer_id, buffer_transaction_id);
 919                    }
 920                }
 921            }
 922        }
 923    }
 924
 925    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 926        self.history.finalize_last_transaction();
 927        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 928            buffer.update(cx, |buffer, _| {
 929                buffer.finalize_last_transaction();
 930            });
 931        }
 932    }
 933
 934    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &ModelContext<Self>)
 935    where
 936        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
 937    {
 938        self.history
 939            .push_transaction(buffer_transactions, Instant::now(), cx);
 940        self.history.finalize_last_transaction();
 941    }
 942
 943    pub fn group_until_transaction(
 944        &mut self,
 945        transaction_id: TransactionId,
 946        cx: &mut ModelContext<Self>,
 947    ) {
 948        if let Some(buffer) = self.as_singleton() {
 949            buffer.update(cx, |buffer, _| {
 950                buffer.group_until_transaction(transaction_id)
 951            });
 952        } else {
 953            self.history.group_until(transaction_id);
 954        }
 955    }
 956
 957    pub fn set_active_selections(
 958        &self,
 959        selections: &[Selection<Anchor>],
 960        line_mode: bool,
 961        cursor_shape: CursorShape,
 962        cx: &mut ModelContext<Self>,
 963    ) {
 964        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
 965            Default::default();
 966        let snapshot = self.read(cx);
 967        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
 968        for selection in selections {
 969            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 970            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 971
 972            cursor.seek(&Some(start_locator), Bias::Left, &());
 973            while let Some(excerpt) = cursor.item() {
 974                if excerpt.locator > *end_locator {
 975                    break;
 976                }
 977
 978                let mut start = excerpt.range.context.start;
 979                let mut end = excerpt.range.context.end;
 980                if excerpt.id == selection.start.excerpt_id {
 981                    start = selection.start.text_anchor;
 982                }
 983                if excerpt.id == selection.end.excerpt_id {
 984                    end = selection.end.text_anchor;
 985                }
 986                selections_by_buffer
 987                    .entry(excerpt.buffer_id)
 988                    .or_default()
 989                    .push(Selection {
 990                        id: selection.id,
 991                        start,
 992                        end,
 993                        reversed: selection.reversed,
 994                        goal: selection.goal,
 995                    });
 996
 997                cursor.next(&());
 998            }
 999        }
1000
1001        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
1002            if !selections_by_buffer.contains_key(buffer_id) {
1003                buffer_state
1004                    .buffer
1005                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1006            }
1007        }
1008
1009        for (buffer_id, mut selections) in selections_by_buffer {
1010            self.buffers.borrow()[&buffer_id]
1011                .buffer
1012                .update(cx, |buffer, cx| {
1013                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1014                    let mut selections = selections.into_iter().peekable();
1015                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
1016                        let mut selection = selections.next()?;
1017                        while let Some(next_selection) = selections.peek() {
1018                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1019                                let next_selection = selections.next().unwrap();
1020                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1021                                    selection.end = next_selection.end;
1022                                }
1023                            } else {
1024                                break;
1025                            }
1026                        }
1027                        Some(selection)
1028                    }));
1029                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1030                });
1031        }
1032    }
1033
1034    pub fn remove_active_selections(&self, cx: &mut ModelContext<Self>) {
1035        for buffer in self.buffers.borrow().values() {
1036            buffer
1037                .buffer
1038                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1039        }
1040    }
1041
1042    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
1043        let mut transaction_id = None;
1044        if let Some(buffer) = self.as_singleton() {
1045            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
1046        } else {
1047            while let Some(transaction) = self.history.pop_undo() {
1048                let mut undone = false;
1049                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1050                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1051                        undone |= buffer.update(cx, |buffer, cx| {
1052                            let undo_to = *buffer_transaction_id;
1053                            if let Some(entry) = buffer.peek_undo_stack() {
1054                                *buffer_transaction_id = entry.transaction_id();
1055                            }
1056                            buffer.undo_to_transaction(undo_to, cx)
1057                        });
1058                    }
1059                }
1060
1061                if undone {
1062                    transaction_id = Some(transaction.id);
1063                    break;
1064                }
1065            }
1066        }
1067
1068        if let Some(transaction_id) = transaction_id {
1069            cx.emit(Event::TransactionUndone { transaction_id });
1070        }
1071
1072        transaction_id
1073    }
1074
1075    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
1076        if let Some(buffer) = self.as_singleton() {
1077            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
1078        }
1079
1080        while let Some(transaction) = self.history.pop_redo() {
1081            let mut redone = false;
1082            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
1083                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1084                    redone |= buffer.update(cx, |buffer, cx| {
1085                        let redo_to = *buffer_transaction_id;
1086                        if let Some(entry) = buffer.peek_redo_stack() {
1087                            *buffer_transaction_id = entry.transaction_id();
1088                        }
1089                        buffer.redo_to_transaction(redo_to, cx)
1090                    });
1091                }
1092            }
1093
1094            if redone {
1095                return Some(transaction.id);
1096            }
1097        }
1098
1099        None
1100    }
1101
1102    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
1103        if let Some(buffer) = self.as_singleton() {
1104            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
1105        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
1106            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
1107                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
1108                    buffer.update(cx, |buffer, cx| {
1109                        buffer.undo_transaction(*transaction_id, cx)
1110                    });
1111                }
1112            }
1113        }
1114    }
1115
1116    pub fn forget_transaction(
1117        &mut self,
1118        transaction_id: TransactionId,
1119        cx: &mut ModelContext<Self>,
1120    ) {
1121        if let Some(buffer) = self.as_singleton() {
1122            buffer.update(cx, |buffer, _| {
1123                buffer.forget_transaction(transaction_id);
1124            });
1125        } else if let Some(transaction) = self.history.forget(transaction_id) {
1126            for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
1127                if let Some(state) = self.buffers.borrow_mut().get_mut(&buffer_id) {
1128                    state.buffer.update(cx, |buffer, _| {
1129                        buffer.forget_transaction(buffer_transaction_id);
1130                    });
1131                }
1132            }
1133        }
1134    }
1135
1136    pub fn push_excerpts<O>(
1137        &mut self,
1138        buffer: Model<Buffer>,
1139        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1140        cx: &mut ModelContext<Self>,
1141    ) -> Vec<ExcerptId>
1142    where
1143        O: text::ToOffset,
1144    {
1145        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1146    }
1147
1148    pub fn push_excerpts_with_context_lines<O>(
1149        &mut self,
1150        buffer: Model<Buffer>,
1151        ranges: Vec<Range<O>>,
1152        context_line_count: u32,
1153        cx: &mut ModelContext<Self>,
1154    ) -> Vec<Range<Anchor>>
1155    where
1156        O: text::ToPoint + text::ToOffset,
1157    {
1158        let buffer_id = buffer.read(cx).remote_id();
1159        let buffer_snapshot = buffer.read(cx).snapshot();
1160        let (excerpt_ranges, range_counts) =
1161            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
1162
1163        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
1164
1165        let mut anchor_ranges = Vec::new();
1166        let mut ranges = ranges.into_iter();
1167        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
1168            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
1169                let start = Anchor {
1170                    buffer_id: Some(buffer_id),
1171                    excerpt_id,
1172                    text_anchor: buffer_snapshot.anchor_after(range.start),
1173                };
1174                let end = Anchor {
1175                    buffer_id: Some(buffer_id),
1176                    excerpt_id,
1177                    text_anchor: buffer_snapshot.anchor_after(range.end),
1178                };
1179                start..end
1180            }))
1181        }
1182        anchor_ranges
1183    }
1184
1185    pub fn push_multiple_excerpts_with_context_lines(
1186        &self,
1187        buffers_with_ranges: Vec<(Model<Buffer>, Vec<Range<text::Anchor>>)>,
1188        context_line_count: u32,
1189        cx: &mut ModelContext<Self>,
1190    ) -> Task<Vec<Range<Anchor>>> {
1191        use futures::StreamExt;
1192
1193        let (excerpt_ranges_tx, mut excerpt_ranges_rx) = mpsc::channel(256);
1194
1195        let mut buffer_ids = Vec::with_capacity(buffers_with_ranges.len());
1196
1197        for (buffer, ranges) in buffers_with_ranges {
1198            let (buffer_id, buffer_snapshot) =
1199                buffer.update(cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
1200
1201            buffer_ids.push(buffer_id);
1202
1203            cx.background_executor()
1204                .spawn({
1205                    let mut excerpt_ranges_tx = excerpt_ranges_tx.clone();
1206
1207                    async move {
1208                        let (excerpt_ranges, counts) =
1209                            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
1210                        excerpt_ranges_tx
1211                            .send((buffer_id, buffer.clone(), ranges, excerpt_ranges, counts))
1212                            .await
1213                            .ok();
1214                    }
1215                })
1216                .detach()
1217        }
1218
1219        cx.spawn(move |this, mut cx| async move {
1220            let mut results_by_buffer_id = HashMap::default();
1221            while let Some((buffer_id, buffer, ranges, excerpt_ranges, range_counts)) =
1222                excerpt_ranges_rx.next().await
1223            {
1224                results_by_buffer_id
1225                    .insert(buffer_id, (buffer, ranges, excerpt_ranges, range_counts));
1226            }
1227
1228            let mut multi_buffer_ranges = Vec::default();
1229            'outer: for buffer_id in buffer_ids {
1230                let Some((buffer, ranges, excerpt_ranges, range_counts)) =
1231                    results_by_buffer_id.remove(&buffer_id)
1232                else {
1233                    continue;
1234                };
1235
1236                let mut ranges = ranges.into_iter();
1237                let mut range_counts = range_counts.into_iter();
1238                for excerpt_ranges in excerpt_ranges.chunks(100) {
1239                    let excerpt_ids = match this.update(&mut cx, |this, cx| {
1240                        this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
1241                    }) {
1242                        Ok(excerpt_ids) => excerpt_ids,
1243                        Err(_) => continue 'outer,
1244                    };
1245
1246                    for (excerpt_id, range_count) in
1247                        excerpt_ids.into_iter().zip(range_counts.by_ref())
1248                    {
1249                        for range in ranges.by_ref().take(range_count) {
1250                            let start = Anchor {
1251                                buffer_id: Some(buffer_id),
1252                                excerpt_id,
1253                                text_anchor: range.start,
1254                            };
1255                            let end = Anchor {
1256                                buffer_id: Some(buffer_id),
1257                                excerpt_id,
1258                                text_anchor: range.end,
1259                            };
1260                            multi_buffer_ranges.push(start..end);
1261                        }
1262                    }
1263                }
1264            }
1265
1266            multi_buffer_ranges
1267        })
1268    }
1269
1270    pub fn insert_excerpts_after<O>(
1271        &mut self,
1272        prev_excerpt_id: ExcerptId,
1273        buffer: Model<Buffer>,
1274        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1275        cx: &mut ModelContext<Self>,
1276    ) -> Vec<ExcerptId>
1277    where
1278        O: text::ToOffset,
1279    {
1280        let mut ids = Vec::new();
1281        let mut next_excerpt_id =
1282            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1283                last_entry.id.0 + 1
1284            } else {
1285                1
1286            };
1287        self.insert_excerpts_with_ids_after(
1288            prev_excerpt_id,
1289            buffer,
1290            ranges.into_iter().map(|range| {
1291                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1292                ids.push(id);
1293                (id, range)
1294            }),
1295            cx,
1296        );
1297        ids
1298    }
1299
1300    pub fn insert_excerpts_with_ids_after<O>(
1301        &mut self,
1302        prev_excerpt_id: ExcerptId,
1303        buffer: Model<Buffer>,
1304        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1305        cx: &mut ModelContext<Self>,
1306    ) where
1307        O: text::ToOffset,
1308    {
1309        assert_eq!(self.history.transaction_depth, 0);
1310        let mut ranges = ranges.into_iter().peekable();
1311        if ranges.peek().is_none() {
1312            return Default::default();
1313        }
1314
1315        self.sync(cx);
1316
1317        let buffer_id = buffer.read(cx).remote_id();
1318        let buffer_snapshot = buffer.read(cx).snapshot();
1319
1320        let mut buffers = self.buffers.borrow_mut();
1321        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
1322            last_version: buffer_snapshot.version().clone(),
1323            last_non_text_state_update_count: buffer_snapshot.non_text_state_update_count(),
1324            excerpts: Default::default(),
1325            _subscriptions: [
1326                cx.observe(&buffer, |_, _, cx| cx.notify()),
1327                cx.subscribe(&buffer, Self::on_buffer_event),
1328            ],
1329            buffer: buffer.clone(),
1330        });
1331
1332        let mut snapshot = self.snapshot.borrow_mut();
1333
1334        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1335        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1336        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1337        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
1338        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1339
1340        let edit_start = new_excerpts.summary().text.len;
1341        new_excerpts.update_last(
1342            |excerpt| {
1343                excerpt.has_trailing_newline = true;
1344            },
1345            &(),
1346        );
1347
1348        let next_locator = if let Some(excerpt) = cursor.item() {
1349            excerpt.locator.clone()
1350        } else {
1351            Locator::max()
1352        };
1353
1354        let mut excerpts = Vec::new();
1355        while let Some((id, range)) = ranges.next() {
1356            let locator = Locator::between(&prev_locator, &next_locator);
1357            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1358                buffer_state.excerpts.insert(ix, locator.clone());
1359            }
1360            let range = ExcerptRange {
1361                context: buffer_snapshot.anchor_before(&range.context.start)
1362                    ..buffer_snapshot.anchor_after(&range.context.end),
1363                primary: range.primary.map(|primary| {
1364                    buffer_snapshot.anchor_before(&primary.start)
1365                        ..buffer_snapshot.anchor_after(&primary.end)
1366                }),
1367            };
1368            excerpts.push((id, range.clone()));
1369            let excerpt = Excerpt::new(
1370                id,
1371                locator.clone(),
1372                buffer_id,
1373                buffer_snapshot.clone(),
1374                range,
1375                ranges.peek().is_some() || cursor.item().is_some(),
1376            );
1377            new_excerpts.push(excerpt, &());
1378            prev_locator = locator.clone();
1379
1380            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1381                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1382            }
1383            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
1384        }
1385
1386        let edit_end = new_excerpts.summary().text.len;
1387
1388        let suffix = cursor.suffix(&());
1389        let changed_trailing_excerpt = suffix.is_empty();
1390        new_excerpts.append(suffix, &());
1391        drop(cursor);
1392        snapshot.excerpts = new_excerpts;
1393        snapshot.excerpt_ids = new_excerpt_ids;
1394        if changed_trailing_excerpt {
1395            snapshot.trailing_excerpt_update_count += 1;
1396        }
1397
1398        self.subscriptions.publish_mut([Edit {
1399            old: edit_start..edit_start,
1400            new: edit_start..edit_end,
1401        }]);
1402        cx.emit(Event::Edited {
1403            singleton_buffer_edited: false,
1404        });
1405        cx.emit(Event::ExcerptsAdded {
1406            buffer,
1407            predecessor: prev_excerpt_id,
1408            excerpts,
1409        });
1410        cx.notify();
1411    }
1412
1413    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1414        self.sync(cx);
1415        let ids = self.excerpt_ids();
1416        self.buffers.borrow_mut().clear();
1417        let mut snapshot = self.snapshot.borrow_mut();
1418        let prev_len = snapshot.len();
1419        snapshot.excerpts = Default::default();
1420        snapshot.trailing_excerpt_update_count += 1;
1421        snapshot.is_dirty = false;
1422        snapshot.has_conflict = false;
1423
1424        self.subscriptions.publish_mut([Edit {
1425            old: 0..prev_len,
1426            new: 0..0,
1427        }]);
1428        cx.emit(Event::Edited {
1429            singleton_buffer_edited: false,
1430        });
1431        cx.emit(Event::ExcerptsRemoved { ids });
1432        cx.notify();
1433    }
1434
1435    pub fn excerpts_for_buffer(
1436        &self,
1437        buffer: &Model<Buffer>,
1438        cx: &AppContext,
1439    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1440        let mut excerpts = Vec::new();
1441        let snapshot = self.read(cx);
1442        let buffers = self.buffers.borrow();
1443        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(&());
1444        for locator in buffers
1445            .get(&buffer.read(cx).remote_id())
1446            .map(|state| &state.excerpts)
1447            .into_iter()
1448            .flatten()
1449        {
1450            cursor.seek_forward(&Some(locator), Bias::Left, &());
1451            if let Some(excerpt) = cursor.item() {
1452                if excerpt.locator == *locator {
1453                    excerpts.push((excerpt.id, excerpt.range.clone()));
1454                }
1455            }
1456        }
1457
1458        excerpts
1459    }
1460
1461    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
1462        self.snapshot
1463            .borrow()
1464            .excerpts
1465            .iter()
1466            .map(|entry| entry.buffer_id)
1467            .collect()
1468    }
1469
1470    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1471        self.snapshot
1472            .borrow()
1473            .excerpts
1474            .iter()
1475            .map(|entry| entry.id)
1476            .collect()
1477    }
1478
1479    pub fn excerpt_containing(
1480        &self,
1481        position: impl ToOffset,
1482        cx: &AppContext,
1483    ) -> Option<(ExcerptId, Model<Buffer>, Range<text::Anchor>)> {
1484        let snapshot = self.read(cx);
1485        let position = position.to_offset(&snapshot);
1486
1487        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1488        cursor.seek(&position, Bias::Right, &());
1489        cursor
1490            .item()
1491            .or_else(|| snapshot.excerpts.last())
1492            .map(|excerpt| {
1493                (
1494                    excerpt.id,
1495                    self.buffers
1496                        .borrow()
1497                        .get(&excerpt.buffer_id)
1498                        .unwrap()
1499                        .buffer
1500                        .clone(),
1501                    excerpt.range.context.clone(),
1502                )
1503            })
1504    }
1505
1506    // If point is at the end of the buffer, the last excerpt is returned
1507    pub fn point_to_buffer_offset<T: ToOffset>(
1508        &self,
1509        point: T,
1510        cx: &AppContext,
1511    ) -> Option<(Model<Buffer>, usize, ExcerptId)> {
1512        let snapshot = self.read(cx);
1513        let offset = point.to_offset(&snapshot);
1514        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1515        cursor.seek(&offset, Bias::Right, &());
1516        if cursor.item().is_none() {
1517            cursor.prev(&());
1518        }
1519
1520        cursor.item().map(|excerpt| {
1521            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1522            let buffer_point = excerpt_start + offset - *cursor.start();
1523            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1524
1525            (buffer, buffer_point, excerpt.id)
1526        })
1527    }
1528
1529    // If point is at the end of the buffer, the last excerpt is returned
1530    pub fn point_to_buffer_point<T: ToPoint>(
1531        &self,
1532        point: T,
1533        cx: &AppContext,
1534    ) -> Option<(Model<Buffer>, Point, ExcerptId)> {
1535        let snapshot = self.read(cx);
1536        let point = point.to_point(&snapshot);
1537        let mut cursor = snapshot.excerpts.cursor::<Point>(&());
1538        cursor.seek(&point, Bias::Right, &());
1539        if cursor.item().is_none() {
1540            cursor.prev(&());
1541        }
1542
1543        cursor.item().map(|excerpt| {
1544            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
1545            let buffer_point = excerpt_start + point - *cursor.start();
1546            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1547
1548            (buffer, buffer_point, excerpt.id)
1549        })
1550    }
1551
1552    pub fn range_to_buffer_ranges<T: ToOffset>(
1553        &self,
1554        range: Range<T>,
1555        cx: &AppContext,
1556    ) -> Vec<(Model<Buffer>, Range<usize>, ExcerptId)> {
1557        let snapshot = self.read(cx);
1558        let start = range.start.to_offset(&snapshot);
1559        let end = range.end.to_offset(&snapshot);
1560
1561        let mut result = Vec::new();
1562        let mut cursor = snapshot.excerpts.cursor::<usize>(&());
1563        cursor.seek(&start, Bias::Right, &());
1564        if cursor.item().is_none() {
1565            cursor.prev(&());
1566        }
1567
1568        while let Some(excerpt) = cursor.item() {
1569            if *cursor.start() > end {
1570                break;
1571            }
1572
1573            let mut end_before_newline = cursor.end(&());
1574            if excerpt.has_trailing_newline {
1575                end_before_newline -= 1;
1576            }
1577            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1578            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1579            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1580            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1581            result.push((buffer, start..end, excerpt.id));
1582            cursor.next(&());
1583        }
1584
1585        result
1586    }
1587
1588    pub fn remove_excerpts(
1589        &mut self,
1590        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1591        cx: &mut ModelContext<Self>,
1592    ) {
1593        self.sync(cx);
1594        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1595        if ids.is_empty() {
1596            return;
1597        }
1598
1599        let mut buffers = self.buffers.borrow_mut();
1600        let mut snapshot = self.snapshot.borrow_mut();
1601        let mut new_excerpts = SumTree::default();
1602        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1603        let mut edits = Vec::new();
1604        let mut excerpt_ids = ids.iter().copied().peekable();
1605
1606        while let Some(excerpt_id) = excerpt_ids.next() {
1607            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1608            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1609            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1610
1611            if let Some(mut excerpt) = cursor.item() {
1612                if excerpt.id != excerpt_id {
1613                    continue;
1614                }
1615                let mut old_start = cursor.start().1;
1616
1617                // Skip over the removed excerpt.
1618                'remove_excerpts: loop {
1619                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1620                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1621                        if buffer_state.excerpts.is_empty() {
1622                            buffers.remove(&excerpt.buffer_id);
1623                        }
1624                    }
1625                    cursor.next(&());
1626
1627                    // Skip over any subsequent excerpts that are also removed.
1628                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
1629                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1630                        if let Some(next_excerpt) = cursor.item() {
1631                            if next_excerpt.locator == *next_locator {
1632                                excerpt_ids.next();
1633                                excerpt = next_excerpt;
1634                                continue 'remove_excerpts;
1635                            }
1636                        }
1637                    }
1638
1639                    break;
1640                }
1641
1642                // When removing the last excerpt, remove the trailing newline from
1643                // the previous excerpt.
1644                if cursor.item().is_none() && old_start > 0 {
1645                    old_start -= 1;
1646                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1647                }
1648
1649                // Push an edit for the removal of this run of excerpts.
1650                let old_end = cursor.start().1;
1651                let new_start = new_excerpts.summary().text.len;
1652                edits.push(Edit {
1653                    old: old_start..old_end,
1654                    new: new_start..new_start,
1655                });
1656            }
1657        }
1658        let suffix = cursor.suffix(&());
1659        let changed_trailing_excerpt = suffix.is_empty();
1660        new_excerpts.append(suffix, &());
1661        drop(cursor);
1662        snapshot.excerpts = new_excerpts;
1663
1664        if changed_trailing_excerpt {
1665            snapshot.trailing_excerpt_update_count += 1;
1666        }
1667
1668        self.subscriptions.publish_mut(edits);
1669        cx.emit(Event::Edited {
1670            singleton_buffer_edited: false,
1671        });
1672        cx.emit(Event::ExcerptsRemoved { ids });
1673        cx.notify();
1674    }
1675
1676    pub fn wait_for_anchors<'a>(
1677        &self,
1678        anchors: impl 'a + Iterator<Item = Anchor>,
1679        cx: &mut ModelContext<Self>,
1680    ) -> impl 'static + Future<Output = Result<()>> {
1681        let borrow = self.buffers.borrow();
1682        let mut error = None;
1683        let mut futures = Vec::new();
1684        for anchor in anchors {
1685            if let Some(buffer_id) = anchor.buffer_id {
1686                if let Some(buffer) = borrow.get(&buffer_id) {
1687                    buffer.buffer.update(cx, |buffer, _| {
1688                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1689                    });
1690                } else {
1691                    error = Some(anyhow!(
1692                        "buffer {buffer_id} is not part of this multi-buffer"
1693                    ));
1694                    break;
1695                }
1696            }
1697        }
1698        async move {
1699            if let Some(error) = error {
1700                Err(error)?;
1701            }
1702            for future in futures {
1703                future.await?;
1704            }
1705            Ok(())
1706        }
1707    }
1708
1709    pub fn text_anchor_for_position<T: ToOffset>(
1710        &self,
1711        position: T,
1712        cx: &AppContext,
1713    ) -> Option<(Model<Buffer>, language::Anchor)> {
1714        let snapshot = self.read(cx);
1715        let anchor = snapshot.anchor_before(position);
1716        let buffer = self
1717            .buffers
1718            .borrow()
1719            .get(&anchor.buffer_id?)?
1720            .buffer
1721            .clone();
1722        Some((buffer, anchor.text_anchor))
1723    }
1724
1725    fn on_buffer_event(
1726        &mut self,
1727        buffer: Model<Buffer>,
1728        event: &language::BufferEvent,
1729        cx: &mut ModelContext<Self>,
1730    ) {
1731        cx.emit(match event {
1732            language::BufferEvent::Edited => Event::Edited {
1733                singleton_buffer_edited: true,
1734            },
1735            language::BufferEvent::DirtyChanged => Event::DirtyChanged,
1736            language::BufferEvent::Saved => Event::Saved,
1737            language::BufferEvent::FileHandleChanged => Event::FileHandleChanged,
1738            language::BufferEvent::Reloaded => Event::Reloaded,
1739            language::BufferEvent::ReloadNeeded => Event::ReloadNeeded,
1740            language::BufferEvent::DiffBaseChanged => Event::DiffBaseChanged,
1741            language::BufferEvent::DiffUpdated => Event::DiffUpdated { buffer },
1742            language::BufferEvent::LanguageChanged => {
1743                Event::LanguageChanged(buffer.read(cx).remote_id())
1744            }
1745            language::BufferEvent::Reparsed => Event::Reparsed(buffer.read(cx).remote_id()),
1746            language::BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1747            language::BufferEvent::Closed => Event::Closed,
1748            language::BufferEvent::Discarded => Event::Discarded,
1749            language::BufferEvent::CapabilityChanged => {
1750                self.capability = buffer.read(cx).capability();
1751                Event::CapabilityChanged
1752            }
1753            //
1754            language::BufferEvent::Operation { .. } => return,
1755        });
1756    }
1757
1758    pub fn all_buffers(&self) -> HashSet<Model<Buffer>> {
1759        self.buffers
1760            .borrow()
1761            .values()
1762            .map(|state| state.buffer.clone())
1763            .collect()
1764    }
1765
1766    pub fn buffer(&self, buffer_id: BufferId) -> Option<Model<Buffer>> {
1767        self.buffers
1768            .borrow()
1769            .get(&buffer_id)
1770            .map(|state| state.buffer.clone())
1771    }
1772
1773    pub fn language_at<T: ToOffset>(&self, point: T, cx: &AppContext) -> Option<Arc<Language>> {
1774        self.point_to_buffer_offset(point, cx)
1775            .and_then(|(buffer, offset, _)| buffer.read(cx).language_at(offset))
1776    }
1777
1778    pub fn settings_at<'a, T: ToOffset>(
1779        &self,
1780        point: T,
1781        cx: &'a AppContext,
1782    ) -> Cow<'a, LanguageSettings> {
1783        let mut language = None;
1784        let mut file = None;
1785        if let Some((buffer, offset, _)) = self.point_to_buffer_offset(point, cx) {
1786            let buffer = buffer.read(cx);
1787            language = buffer.language_at(offset);
1788            file = buffer.file();
1789        }
1790        language_settings(language.map(|l| l.name()), file, cx)
1791    }
1792
1793    pub fn for_each_buffer(&self, mut f: impl FnMut(&Model<Buffer>)) {
1794        self.buffers
1795            .borrow()
1796            .values()
1797            .for_each(|state| f(&state.buffer))
1798    }
1799
1800    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1801        if let Some(title) = self.title.as_ref() {
1802            return title.into();
1803        }
1804
1805        if let Some(buffer) = self.as_singleton() {
1806            if let Some(file) = buffer.read(cx).file() {
1807                return file.file_name(cx).to_string_lossy();
1808            }
1809        }
1810
1811        "untitled".into()
1812    }
1813
1814    pub fn set_title(&mut self, title: String, cx: &mut ModelContext<Self>) {
1815        self.title = Some(title);
1816        cx.notify();
1817    }
1818
1819    /// Preserve preview tabs containing this multibuffer until additional edits occur.
1820    pub fn refresh_preview(&self, cx: &mut ModelContext<Self>) {
1821        for buffer_state in self.buffers.borrow().values() {
1822            buffer_state
1823                .buffer
1824                .update(cx, |buffer, _cx| buffer.refresh_preview());
1825        }
1826    }
1827
1828    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
1829    pub fn preserve_preview(&self, cx: &AppContext) -> bool {
1830        self.buffers
1831            .borrow()
1832            .values()
1833            .all(|state| state.buffer.read(cx).preserve_preview())
1834    }
1835
1836    #[cfg(any(test, feature = "test-support"))]
1837    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1838        self.as_singleton().unwrap().read(cx).is_parsing()
1839    }
1840
1841    pub fn resize_excerpt(
1842        &mut self,
1843        id: ExcerptId,
1844        range: Range<text::Anchor>,
1845        cx: &mut ModelContext<Self>,
1846    ) {
1847        self.sync(cx);
1848
1849        let snapshot = self.snapshot(cx);
1850        let locator = snapshot.excerpt_locator_for_id(id);
1851        let mut new_excerpts = SumTree::default();
1852        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1853        let mut edits = Vec::<Edit<usize>>::new();
1854
1855        let prefix = cursor.slice(&Some(locator), Bias::Left, &());
1856        new_excerpts.append(prefix, &());
1857
1858        let mut excerpt = cursor.item().unwrap().clone();
1859        let old_text_len = excerpt.text_summary.len;
1860
1861        excerpt.range.context.start = range.start;
1862        excerpt.range.context.end = range.end;
1863        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
1864
1865        excerpt.text_summary = excerpt
1866            .buffer
1867            .text_summary_for_range(excerpt.range.context.clone());
1868
1869        let new_start_offset = new_excerpts.summary().text.len;
1870        let old_start_offset = cursor.start().1;
1871        let edit = Edit {
1872            old: old_start_offset..old_start_offset + old_text_len,
1873            new: new_start_offset..new_start_offset + excerpt.text_summary.len,
1874        };
1875
1876        if let Some(last_edit) = edits.last_mut() {
1877            if last_edit.old.end == edit.old.start {
1878                last_edit.old.end = edit.old.end;
1879                last_edit.new.end = edit.new.end;
1880            } else {
1881                edits.push(edit);
1882            }
1883        } else {
1884            edits.push(edit);
1885        }
1886
1887        new_excerpts.push(excerpt, &());
1888
1889        cursor.next(&());
1890
1891        new_excerpts.append(cursor.suffix(&()), &());
1892
1893        drop(cursor);
1894        self.snapshot.borrow_mut().excerpts = new_excerpts;
1895
1896        self.subscriptions.publish_mut(edits);
1897        cx.emit(Event::Edited {
1898            singleton_buffer_edited: false,
1899        });
1900        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
1901        cx.notify();
1902    }
1903
1904    pub fn expand_excerpts(
1905        &mut self,
1906        ids: impl IntoIterator<Item = ExcerptId>,
1907        line_count: u32,
1908        direction: ExpandExcerptDirection,
1909        cx: &mut ModelContext<Self>,
1910    ) {
1911        if line_count == 0 {
1912            return;
1913        }
1914        self.sync(cx);
1915
1916        let ids = ids.into_iter().collect::<Vec<_>>();
1917        let snapshot = self.snapshot(cx);
1918        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
1919        let mut new_excerpts = SumTree::default();
1920        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
1921        let mut edits = Vec::<Edit<usize>>::new();
1922
1923        for locator in &locators {
1924            let prefix = cursor.slice(&Some(locator), Bias::Left, &());
1925            new_excerpts.append(prefix, &());
1926
1927            let mut excerpt = cursor.item().unwrap().clone();
1928            let old_text_len = excerpt.text_summary.len;
1929
1930            let up_line_count = if direction.should_expand_up() {
1931                line_count
1932            } else {
1933                0
1934            };
1935
1936            let start_row = excerpt
1937                .range
1938                .context
1939                .start
1940                .to_point(&excerpt.buffer)
1941                .row
1942                .saturating_sub(up_line_count);
1943            let start_point = Point::new(start_row, 0);
1944            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
1945
1946            let down_line_count = if direction.should_expand_down() {
1947                line_count
1948            } else {
1949                0
1950            };
1951
1952            let mut end_point = excerpt.buffer.clip_point(
1953                excerpt.range.context.end.to_point(&excerpt.buffer)
1954                    + Point::new(down_line_count, 0),
1955                Bias::Left,
1956            );
1957            end_point.column = excerpt.buffer.line_len(end_point.row);
1958            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
1959            excerpt.max_buffer_row = end_point.row;
1960
1961            excerpt.text_summary = excerpt
1962                .buffer
1963                .text_summary_for_range(excerpt.range.context.clone());
1964
1965            let new_start_offset = new_excerpts.summary().text.len;
1966            let old_start_offset = cursor.start().1;
1967            let edit = Edit {
1968                old: old_start_offset..old_start_offset + old_text_len,
1969                new: new_start_offset..new_start_offset + excerpt.text_summary.len,
1970            };
1971
1972            if let Some(last_edit) = edits.last_mut() {
1973                if last_edit.old.end == edit.old.start {
1974                    last_edit.old.end = edit.old.end;
1975                    last_edit.new.end = edit.new.end;
1976                } else {
1977                    edits.push(edit);
1978                }
1979            } else {
1980                edits.push(edit);
1981            }
1982
1983            new_excerpts.push(excerpt, &());
1984
1985            cursor.next(&());
1986        }
1987
1988        new_excerpts.append(cursor.suffix(&()), &());
1989
1990        drop(cursor);
1991        self.snapshot.borrow_mut().excerpts = new_excerpts;
1992
1993        self.subscriptions.publish_mut(edits);
1994        cx.emit(Event::Edited {
1995            singleton_buffer_edited: false,
1996        });
1997        cx.emit(Event::ExcerptsExpanded { ids });
1998        cx.notify();
1999    }
2000
2001    fn sync(&self, cx: &AppContext) {
2002        let mut snapshot = self.snapshot.borrow_mut();
2003        let mut excerpts_to_edit = Vec::new();
2004        let mut non_text_state_updated = false;
2005        let mut is_dirty = false;
2006        let mut has_conflict = false;
2007        let mut edited = false;
2008        let mut buffers = self.buffers.borrow_mut();
2009        for buffer_state in buffers.values_mut() {
2010            let buffer = buffer_state.buffer.read(cx);
2011            let version = buffer.version();
2012            let non_text_state_update_count = buffer.non_text_state_update_count();
2013
2014            let buffer_edited = version.changed_since(&buffer_state.last_version);
2015            let buffer_non_text_state_updated =
2016                non_text_state_update_count > buffer_state.last_non_text_state_update_count;
2017            if buffer_edited || buffer_non_text_state_updated {
2018                buffer_state.last_version = version;
2019                buffer_state.last_non_text_state_update_count = non_text_state_update_count;
2020                excerpts_to_edit.extend(
2021                    buffer_state
2022                        .excerpts
2023                        .iter()
2024                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
2025                );
2026            }
2027
2028            edited |= buffer_edited;
2029            non_text_state_updated |= buffer_non_text_state_updated;
2030            is_dirty |= buffer.is_dirty();
2031            has_conflict |= buffer.has_conflict();
2032        }
2033        if edited {
2034            snapshot.edit_count += 1;
2035        }
2036        if non_text_state_updated {
2037            snapshot.non_text_state_update_count += 1;
2038        }
2039        snapshot.is_dirty = is_dirty;
2040        snapshot.has_conflict = has_conflict;
2041
2042        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
2043
2044        let mut edits = Vec::new();
2045        let mut new_excerpts = SumTree::default();
2046        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>(&());
2047
2048        for (locator, buffer, buffer_edited) in excerpts_to_edit {
2049            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
2050            let old_excerpt = cursor.item().unwrap();
2051            let buffer = buffer.read(cx);
2052            let buffer_id = buffer.remote_id();
2053
2054            let mut new_excerpt;
2055            if buffer_edited {
2056                edits.extend(
2057                    buffer
2058                        .edits_since_in_range::<usize>(
2059                            old_excerpt.buffer.version(),
2060                            old_excerpt.range.context.clone(),
2061                        )
2062                        .map(|mut edit| {
2063                            let excerpt_old_start = cursor.start().1;
2064                            let excerpt_new_start = new_excerpts.summary().text.len;
2065                            edit.old.start += excerpt_old_start;
2066                            edit.old.end += excerpt_old_start;
2067                            edit.new.start += excerpt_new_start;
2068                            edit.new.end += excerpt_new_start;
2069                            edit
2070                        }),
2071                );
2072
2073                new_excerpt = Excerpt::new(
2074                    old_excerpt.id,
2075                    locator.clone(),
2076                    buffer_id,
2077                    buffer.snapshot(),
2078                    old_excerpt.range.clone(),
2079                    old_excerpt.has_trailing_newline,
2080                );
2081            } else {
2082                new_excerpt = old_excerpt.clone();
2083                new_excerpt.buffer = buffer.snapshot();
2084            }
2085
2086            new_excerpts.push(new_excerpt, &());
2087            cursor.next(&());
2088        }
2089        new_excerpts.append(cursor.suffix(&()), &());
2090
2091        drop(cursor);
2092        snapshot.excerpts = new_excerpts;
2093
2094        self.subscriptions.publish(edits);
2095    }
2096}
2097
2098#[cfg(any(test, feature = "test-support"))]
2099impl MultiBuffer {
2100    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> Model<Self> {
2101        let buffer = cx.new_model(|cx| Buffer::local(text, cx));
2102        cx.new_model(|cx| Self::singleton(buffer, cx))
2103    }
2104
2105    pub fn build_multi<const COUNT: usize>(
2106        excerpts: [(&str, Vec<Range<Point>>); COUNT],
2107        cx: &mut gpui::AppContext,
2108    ) -> Model<Self> {
2109        let multi = cx.new_model(|_| Self::new(Capability::ReadWrite));
2110        for (text, ranges) in excerpts {
2111            let buffer = cx.new_model(|cx| Buffer::local(text, cx));
2112            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
2113                context: range,
2114                primary: None,
2115            });
2116            multi.update(cx, |multi, cx| {
2117                multi.push_excerpts(buffer, excerpt_ranges, cx)
2118            });
2119        }
2120
2121        multi
2122    }
2123
2124    pub fn build_from_buffer(buffer: Model<Buffer>, cx: &mut gpui::AppContext) -> Model<Self> {
2125        cx.new_model(|cx| Self::singleton(buffer, cx))
2126    }
2127
2128    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> Model<Self> {
2129        cx.new_model(|cx| {
2130            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
2131            let mutation_count = rng.gen_range(1..=5);
2132            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
2133            multibuffer
2134        })
2135    }
2136
2137    pub fn randomly_edit(
2138        &mut self,
2139        rng: &mut impl rand::Rng,
2140        edit_count: usize,
2141        cx: &mut ModelContext<Self>,
2142    ) {
2143        use util::RandomCharIter;
2144
2145        let snapshot = self.read(cx);
2146        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
2147        let mut last_end = None;
2148        for _ in 0..edit_count {
2149            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
2150                break;
2151            }
2152
2153            let new_start = last_end.map_or(0, |last_end| last_end + 1);
2154            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
2155            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
2156            last_end = Some(end);
2157
2158            let mut range = start..end;
2159            if rng.gen_bool(0.2) {
2160                mem::swap(&mut range.start, &mut range.end);
2161            }
2162
2163            let new_text_len = rng.gen_range(0..10);
2164            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
2165
2166            edits.push((range, new_text.into()));
2167        }
2168        log::info!("mutating multi-buffer with {:?}", edits);
2169        drop(snapshot);
2170
2171        self.edit(edits, None, cx);
2172    }
2173
2174    pub fn randomly_edit_excerpts(
2175        &mut self,
2176        rng: &mut impl rand::Rng,
2177        mutation_count: usize,
2178        cx: &mut ModelContext<Self>,
2179    ) {
2180        use rand::prelude::*;
2181        use std::env;
2182        use util::RandomCharIter;
2183
2184        let max_excerpts = env::var("MAX_EXCERPTS")
2185            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
2186            .unwrap_or(5);
2187
2188        let mut buffers = Vec::new();
2189        for _ in 0..mutation_count {
2190            if rng.gen_bool(0.05) {
2191                log::info!("Clearing multi-buffer");
2192                self.clear(cx);
2193                continue;
2194            } else if rng.gen_bool(0.1) && !self.excerpt_ids().is_empty() {
2195                let ids = self.excerpt_ids();
2196                let mut excerpts = HashSet::default();
2197                for _ in 0..rng.gen_range(0..ids.len()) {
2198                    excerpts.extend(ids.choose(rng).copied());
2199                }
2200
2201                let line_count = rng.gen_range(0..5);
2202
2203                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
2204
2205                self.expand_excerpts(
2206                    excerpts.iter().cloned(),
2207                    line_count,
2208                    ExpandExcerptDirection::UpAndDown,
2209                    cx,
2210                );
2211                continue;
2212            }
2213
2214            let excerpt_ids = self.excerpt_ids();
2215            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
2216                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
2217                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
2218                    buffers.push(cx.new_model(|cx| Buffer::local(text, cx)));
2219                    let buffer = buffers.last().unwrap().read(cx);
2220                    log::info!(
2221                        "Creating new buffer {} with text: {:?}",
2222                        buffer.remote_id(),
2223                        buffer.text()
2224                    );
2225                    buffers.last().unwrap().clone()
2226                } else {
2227                    self.buffers
2228                        .borrow()
2229                        .values()
2230                        .choose(rng)
2231                        .unwrap()
2232                        .buffer
2233                        .clone()
2234                };
2235
2236                let buffer = buffer_handle.read(cx);
2237                let buffer_text = buffer.text();
2238                let ranges = (0..rng.gen_range(0..5))
2239                    .map(|_| {
2240                        let end_ix =
2241                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2242                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2243                        ExcerptRange {
2244                            context: start_ix..end_ix,
2245                            primary: None,
2246                        }
2247                    })
2248                    .collect::<Vec<_>>();
2249                log::info!(
2250                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
2251                    buffer_handle.read(cx).remote_id(),
2252                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
2253                    ranges
2254                        .iter()
2255                        .map(|r| &buffer_text[r.context.clone()])
2256                        .collect::<Vec<_>>()
2257                );
2258
2259                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
2260                log::info!("Inserted with ids: {:?}", excerpt_id);
2261            } else {
2262                let remove_count = rng.gen_range(1..=excerpt_ids.len());
2263                let mut excerpts_to_remove = excerpt_ids
2264                    .choose_multiple(rng, remove_count)
2265                    .cloned()
2266                    .collect::<Vec<_>>();
2267                let snapshot = self.snapshot.borrow();
2268                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
2269                drop(snapshot);
2270                log::info!("Removing excerpts {:?}", excerpts_to_remove);
2271                self.remove_excerpts(excerpts_to_remove, cx);
2272            }
2273        }
2274    }
2275
2276    pub fn randomly_mutate(
2277        &mut self,
2278        rng: &mut impl rand::Rng,
2279        mutation_count: usize,
2280        cx: &mut ModelContext<Self>,
2281    ) {
2282        use rand::prelude::*;
2283
2284        if rng.gen_bool(0.7) || self.singleton {
2285            let buffer = self
2286                .buffers
2287                .borrow()
2288                .values()
2289                .choose(rng)
2290                .map(|state| state.buffer.clone());
2291
2292            if let Some(buffer) = buffer {
2293                buffer.update(cx, |buffer, cx| {
2294                    if rng.gen() {
2295                        buffer.randomly_edit(rng, mutation_count, cx);
2296                    } else {
2297                        buffer.randomly_undo_redo(rng, cx);
2298                    }
2299                });
2300            } else {
2301                self.randomly_edit(rng, mutation_count, cx);
2302            }
2303        } else {
2304            self.randomly_edit_excerpts(rng, mutation_count, cx);
2305        }
2306
2307        self.check_invariants(cx);
2308    }
2309
2310    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
2311        let snapshot = self.read(cx);
2312        let excerpts = snapshot.excerpts.items(&());
2313        let excerpt_ids = snapshot.excerpt_ids.items(&());
2314
2315        for (ix, excerpt) in excerpts.iter().enumerate() {
2316            if ix == 0 {
2317                if excerpt.locator <= Locator::min() {
2318                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
2319                }
2320            } else if excerpt.locator <= excerpts[ix - 1].locator {
2321                panic!("excerpts are out-of-order: {:?}", excerpts);
2322            }
2323        }
2324
2325        for (ix, entry) in excerpt_ids.iter().enumerate() {
2326            if ix == 0 {
2327                if entry.id.cmp(&ExcerptId::min(), &snapshot).is_le() {
2328                    panic!("invalid first excerpt id {:?}", entry.id);
2329                }
2330            } else if entry.id <= excerpt_ids[ix - 1].id {
2331                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
2332            }
2333        }
2334    }
2335}
2336
2337impl EventEmitter<Event> for MultiBuffer {}
2338
2339impl MultiBufferSnapshot {
2340    pub fn text(&self) -> String {
2341        self.chunks(0..self.len(), false)
2342            .map(|chunk| chunk.text)
2343            .collect()
2344    }
2345
2346    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2347        let mut offset = position.to_offset(self);
2348        let mut cursor = self.excerpts.cursor::<usize>(&());
2349        cursor.seek(&offset, Bias::Left, &());
2350        let mut excerpt_chunks = cursor.item().map(|excerpt| {
2351            let end_before_footer = cursor.start() + excerpt.text_summary.len;
2352            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2353            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
2354            excerpt.buffer.reversed_chunks_in_range(start..end)
2355        });
2356        iter::from_fn(move || {
2357            if offset == *cursor.start() {
2358                cursor.prev(&());
2359                let excerpt = cursor.item()?;
2360                excerpt_chunks = Some(
2361                    excerpt
2362                        .buffer
2363                        .reversed_chunks_in_range(excerpt.range.context.clone()),
2364                );
2365            }
2366
2367            let excerpt = cursor.item().unwrap();
2368            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
2369                offset -= 1;
2370                Some("\n")
2371            } else {
2372                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
2373                offset -= chunk.len();
2374                Some(chunk)
2375            }
2376        })
2377        .flat_map(|c| c.chars().rev())
2378    }
2379
2380    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2381        let offset = position.to_offset(self);
2382        self.text_for_range(offset..self.len())
2383            .flat_map(|chunk| chunk.chars())
2384    }
2385
2386    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
2387        self.chunks(range, false).map(|chunk| chunk.text)
2388    }
2389
2390    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
2391        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
2392            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
2393    }
2394
2395    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
2396    where
2397        T: ToOffset,
2398    {
2399        let position = position.to_offset(self);
2400        position == self.clip_offset(position, Bias::Left)
2401            && self
2402                .bytes_in_range(position..self.len())
2403                .flatten()
2404                .copied()
2405                .take(needle.len())
2406                .eq(needle.bytes())
2407    }
2408
2409    pub fn surrounding_word<T: ToOffset>(
2410        &self,
2411        start: T,
2412        for_completion: bool,
2413    ) -> (Range<usize>, Option<CharKind>) {
2414        let mut start = start.to_offset(self);
2415        let mut end = start;
2416        let mut next_chars = self.chars_at(start).peekable();
2417        let mut prev_chars = self.reversed_chars_at(start).peekable();
2418
2419        let classifier = self
2420            .char_classifier_at(start)
2421            .for_completion(for_completion);
2422
2423        let word_kind = cmp::max(
2424            prev_chars.peek().copied().map(|c| classifier.kind(c)),
2425            next_chars.peek().copied().map(|c| classifier.kind(c)),
2426        );
2427
2428        for ch in prev_chars {
2429            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
2430                start -= ch.len_utf8();
2431            } else {
2432                break;
2433            }
2434        }
2435
2436        for ch in next_chars {
2437            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
2438                end += ch.len_utf8();
2439            } else {
2440                break;
2441            }
2442        }
2443
2444        (start..end, word_kind)
2445    }
2446
2447    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
2448        if self.singleton {
2449            self.excerpts
2450                .iter()
2451                .next()
2452                .map(|e| (&e.id, e.buffer_id, &e.buffer))
2453        } else {
2454            None
2455        }
2456    }
2457
2458    pub fn len(&self) -> usize {
2459        self.excerpts.summary().text.len
2460    }
2461
2462    pub fn is_empty(&self) -> bool {
2463        self.excerpts.summary().text.len == 0
2464    }
2465
2466    pub fn max_buffer_row(&self) -> MultiBufferRow {
2467        self.excerpts.summary().max_buffer_row
2468    }
2469
2470    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2471        if let Some((_, _, buffer)) = self.as_singleton() {
2472            return buffer.clip_offset(offset, bias);
2473        }
2474
2475        let mut cursor = self.excerpts.cursor::<usize>(&());
2476        cursor.seek(&offset, Bias::Right, &());
2477        let overshoot = if let Some(excerpt) = cursor.item() {
2478            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2479            let buffer_offset = excerpt
2480                .buffer
2481                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
2482            buffer_offset.saturating_sub(excerpt_start)
2483        } else {
2484            0
2485        };
2486        cursor.start() + overshoot
2487    }
2488
2489    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2490        if let Some((_, _, buffer)) = self.as_singleton() {
2491            return buffer.clip_point(point, bias);
2492        }
2493
2494        let mut cursor = self.excerpts.cursor::<Point>(&());
2495        cursor.seek(&point, Bias::Right, &());
2496        let overshoot = if let Some(excerpt) = cursor.item() {
2497            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2498            let buffer_point = excerpt
2499                .buffer
2500                .clip_point(excerpt_start + (point - cursor.start()), bias);
2501            buffer_point.saturating_sub(excerpt_start)
2502        } else {
2503            Point::zero()
2504        };
2505        *cursor.start() + overshoot
2506    }
2507
2508    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2509        if let Some((_, _, buffer)) = self.as_singleton() {
2510            return buffer.clip_offset_utf16(offset, bias);
2511        }
2512
2513        let mut cursor = self.excerpts.cursor::<OffsetUtf16>(&());
2514        cursor.seek(&offset, Bias::Right, &());
2515        let overshoot = if let Some(excerpt) = cursor.item() {
2516            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2517            let buffer_offset = excerpt
2518                .buffer
2519                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
2520            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
2521        } else {
2522            OffsetUtf16(0)
2523        };
2524        *cursor.start() + overshoot
2525    }
2526
2527    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2528        if let Some((_, _, buffer)) = self.as_singleton() {
2529            return buffer.clip_point_utf16(point, bias);
2530        }
2531
2532        let mut cursor = self.excerpts.cursor::<PointUtf16>(&());
2533        cursor.seek(&point.0, Bias::Right, &());
2534        let overshoot = if let Some(excerpt) = cursor.item() {
2535            let excerpt_start = excerpt
2536                .buffer
2537                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2538            let buffer_point = excerpt
2539                .buffer
2540                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
2541            buffer_point.saturating_sub(excerpt_start)
2542        } else {
2543            PointUtf16::zero()
2544        };
2545        *cursor.start() + overshoot
2546    }
2547
2548    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
2549        let range = range.start.to_offset(self)..range.end.to_offset(self);
2550        let mut excerpts = self.excerpts.cursor::<usize>(&());
2551        excerpts.seek(&range.start, Bias::Right, &());
2552
2553        let mut chunk = &[][..];
2554        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2555            let mut excerpt_bytes = excerpt
2556                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
2557            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2558            Some(excerpt_bytes)
2559        } else {
2560            None
2561        };
2562        MultiBufferBytes {
2563            range,
2564            excerpts,
2565            excerpt_bytes,
2566            chunk,
2567        }
2568    }
2569
2570    pub fn reversed_bytes_in_range<T: ToOffset>(
2571        &self,
2572        range: Range<T>,
2573    ) -> ReversedMultiBufferBytes {
2574        let range = range.start.to_offset(self)..range.end.to_offset(self);
2575        let mut excerpts = self.excerpts.cursor::<usize>(&());
2576        excerpts.seek(&range.end, Bias::Left, &());
2577
2578        let mut chunk = &[][..];
2579        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2580            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
2581                range.start.saturating_sub(*excerpts.start())..range.end - *excerpts.start(),
2582            );
2583            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2584            Some(excerpt_bytes)
2585        } else {
2586            None
2587        };
2588
2589        ReversedMultiBufferBytes {
2590            range,
2591            excerpts,
2592            excerpt_bytes,
2593            chunk,
2594        }
2595    }
2596
2597    pub fn buffer_rows(&self, start_row: MultiBufferRow) -> MultiBufferRows {
2598        let mut result = MultiBufferRows {
2599            buffer_row_range: 0..0,
2600            excerpts: self.excerpts.cursor(&()),
2601        };
2602        result.seek(start_row);
2603        result
2604    }
2605
2606    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
2607        let range = range.start.to_offset(self)..range.end.to_offset(self);
2608        let mut chunks = MultiBufferChunks {
2609            range: range.clone(),
2610            excerpts: self.excerpts.cursor(&()),
2611            excerpt_chunks: None,
2612            language_aware,
2613        };
2614        chunks.seek(range);
2615        chunks
2616    }
2617
2618    pub fn offset_to_point(&self, offset: usize) -> Point {
2619        if let Some((_, _, buffer)) = self.as_singleton() {
2620            return buffer.offset_to_point(offset);
2621        }
2622
2623        let mut cursor = self.excerpts.cursor::<(usize, Point)>(&());
2624        cursor.seek(&offset, Bias::Right, &());
2625        if let Some(excerpt) = cursor.item() {
2626            let (start_offset, start_point) = cursor.start();
2627            let overshoot = offset - start_offset;
2628            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2629            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2630            let buffer_point = excerpt
2631                .buffer
2632                .offset_to_point(excerpt_start_offset + overshoot);
2633            *start_point + (buffer_point - excerpt_start_point)
2634        } else {
2635            self.excerpts.summary().text.lines
2636        }
2637    }
2638
2639    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2640        if let Some((_, _, buffer)) = self.as_singleton() {
2641            return buffer.offset_to_point_utf16(offset);
2642        }
2643
2644        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>(&());
2645        cursor.seek(&offset, Bias::Right, &());
2646        if let Some(excerpt) = cursor.item() {
2647            let (start_offset, start_point) = cursor.start();
2648            let overshoot = offset - start_offset;
2649            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2650            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2651            let buffer_point = excerpt
2652                .buffer
2653                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2654            *start_point + (buffer_point - excerpt_start_point)
2655        } else {
2656            self.excerpts.summary().text.lines_utf16()
2657        }
2658    }
2659
2660    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2661        if let Some((_, _, buffer)) = self.as_singleton() {
2662            return buffer.point_to_point_utf16(point);
2663        }
2664
2665        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>(&());
2666        cursor.seek(&point, Bias::Right, &());
2667        if let Some(excerpt) = cursor.item() {
2668            let (start_offset, start_point) = cursor.start();
2669            let overshoot = point - start_offset;
2670            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2671            let excerpt_start_point_utf16 =
2672                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2673            let buffer_point = excerpt
2674                .buffer
2675                .point_to_point_utf16(excerpt_start_point + overshoot);
2676            *start_point + (buffer_point - excerpt_start_point_utf16)
2677        } else {
2678            self.excerpts.summary().text.lines_utf16()
2679        }
2680    }
2681
2682    pub fn point_to_offset(&self, point: Point) -> usize {
2683        if let Some((_, _, buffer)) = self.as_singleton() {
2684            return buffer.point_to_offset(point);
2685        }
2686
2687        let mut cursor = self.excerpts.cursor::<(Point, usize)>(&());
2688        cursor.seek(&point, Bias::Right, &());
2689        if let Some(excerpt) = cursor.item() {
2690            let (start_point, start_offset) = cursor.start();
2691            let overshoot = point - start_point;
2692            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2693            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2694            let buffer_offset = excerpt
2695                .buffer
2696                .point_to_offset(excerpt_start_point + overshoot);
2697            *start_offset + buffer_offset - excerpt_start_offset
2698        } else {
2699            self.excerpts.summary().text.len
2700        }
2701    }
2702
2703    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2704        if let Some((_, _, buffer)) = self.as_singleton() {
2705            return buffer.offset_utf16_to_offset(offset_utf16);
2706        }
2707
2708        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>(&());
2709        cursor.seek(&offset_utf16, Bias::Right, &());
2710        if let Some(excerpt) = cursor.item() {
2711            let (start_offset_utf16, start_offset) = cursor.start();
2712            let overshoot = offset_utf16 - start_offset_utf16;
2713            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2714            let excerpt_start_offset_utf16 =
2715                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2716            let buffer_offset = excerpt
2717                .buffer
2718                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2719            *start_offset + (buffer_offset - excerpt_start_offset)
2720        } else {
2721            self.excerpts.summary().text.len
2722        }
2723    }
2724
2725    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2726        if let Some((_, _, buffer)) = self.as_singleton() {
2727            return buffer.offset_to_offset_utf16(offset);
2728        }
2729
2730        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>(&());
2731        cursor.seek(&offset, Bias::Right, &());
2732        if let Some(excerpt) = cursor.item() {
2733            let (start_offset, start_offset_utf16) = cursor.start();
2734            let overshoot = offset - start_offset;
2735            let excerpt_start_offset_utf16 =
2736                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2737            let excerpt_start_offset = excerpt
2738                .buffer
2739                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2740            let buffer_offset_utf16 = excerpt
2741                .buffer
2742                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2743            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2744        } else {
2745            self.excerpts.summary().text.len_utf16
2746        }
2747    }
2748
2749    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2750        if let Some((_, _, buffer)) = self.as_singleton() {
2751            return buffer.point_utf16_to_offset(point);
2752        }
2753
2754        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>(&());
2755        cursor.seek(&point, Bias::Right, &());
2756        if let Some(excerpt) = cursor.item() {
2757            let (start_point, start_offset) = cursor.start();
2758            let overshoot = point - start_point;
2759            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2760            let excerpt_start_point = excerpt
2761                .buffer
2762                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2763            let buffer_offset = excerpt
2764                .buffer
2765                .point_utf16_to_offset(excerpt_start_point + overshoot);
2766            *start_offset + (buffer_offset - excerpt_start_offset)
2767        } else {
2768            self.excerpts.summary().text.len
2769        }
2770    }
2771
2772    pub fn point_to_buffer_offset<T: ToOffset>(
2773        &self,
2774        point: T,
2775    ) -> Option<(&BufferSnapshot, usize)> {
2776        let offset = point.to_offset(self);
2777        let mut cursor = self.excerpts.cursor::<usize>(&());
2778        cursor.seek(&offset, Bias::Right, &());
2779        if cursor.item().is_none() {
2780            cursor.prev(&());
2781        }
2782
2783        cursor.item().map(|excerpt| {
2784            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2785            let buffer_point = excerpt_start + offset - *cursor.start();
2786            (&excerpt.buffer, buffer_point)
2787        })
2788    }
2789
2790    pub fn suggested_indents(
2791        &self,
2792        rows: impl IntoIterator<Item = u32>,
2793        cx: &AppContext,
2794    ) -> BTreeMap<MultiBufferRow, IndentSize> {
2795        let mut result = BTreeMap::new();
2796
2797        let mut rows_for_excerpt = Vec::new();
2798        let mut cursor = self.excerpts.cursor::<Point>(&());
2799        let mut rows = rows.into_iter().peekable();
2800        let mut prev_row = u32::MAX;
2801        let mut prev_language_indent_size = IndentSize::default();
2802
2803        while let Some(row) = rows.next() {
2804            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2805            let excerpt = match cursor.item() {
2806                Some(excerpt) => excerpt,
2807                _ => continue,
2808            };
2809
2810            // Retrieve the language and indent size once for each disjoint region being indented.
2811            let single_indent_size = if row.saturating_sub(1) == prev_row {
2812                prev_language_indent_size
2813            } else {
2814                excerpt
2815                    .buffer
2816                    .language_indent_size_at(Point::new(row, 0), cx)
2817            };
2818            prev_language_indent_size = single_indent_size;
2819            prev_row = row;
2820
2821            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2822            let start_multibuffer_row = cursor.start().row;
2823
2824            rows_for_excerpt.push(row);
2825            while let Some(next_row) = rows.peek().copied() {
2826                if cursor.end(&()).row > next_row {
2827                    rows_for_excerpt.push(next_row);
2828                    rows.next();
2829                } else {
2830                    break;
2831                }
2832            }
2833
2834            let buffer_rows = rows_for_excerpt
2835                .drain(..)
2836                .map(|row| start_buffer_row + row - start_multibuffer_row);
2837            let buffer_indents = excerpt
2838                .buffer
2839                .suggested_indents(buffer_rows, single_indent_size);
2840            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
2841                (
2842                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
2843                    indent,
2844                )
2845            });
2846            result.extend(multibuffer_indents);
2847        }
2848
2849        result
2850    }
2851
2852    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
2853        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2854            let mut size = buffer.indent_size_for_line(range.start.row);
2855            size.len = size
2856                .len
2857                .min(range.end.column)
2858                .saturating_sub(range.start.column);
2859            size
2860        } else {
2861            IndentSize::spaces(0)
2862        }
2863    }
2864
2865    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &AppContext) -> String {
2866        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
2867
2868        if self.settings_at(0, cx).extend_comment_on_newline {
2869            if let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0)) {
2870                let delimiters = language_scope.line_comment_prefixes();
2871                for delimiter in delimiters {
2872                    if *self
2873                        .chars_at(Point::new(row.0, indent.len() as u32))
2874                        .take(delimiter.chars().count())
2875                        .collect::<String>()
2876                        .as_str()
2877                        == **delimiter
2878                    {
2879                        indent.push_str(&delimiter);
2880                        break;
2881                    }
2882                }
2883            }
2884        }
2885
2886        indent
2887    }
2888
2889    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
2890        while row.0 > 0 {
2891            row.0 -= 1;
2892            if !self.is_line_blank(row) {
2893                return Some(row);
2894            }
2895        }
2896        None
2897    }
2898
2899    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
2900        if let Some((_, range)) = self.buffer_line_for_row(row) {
2901            range.end.column - range.start.column
2902        } else {
2903            0
2904        }
2905    }
2906
2907    pub fn buffer_line_for_row(
2908        &self,
2909        row: MultiBufferRow,
2910    ) -> Option<(&BufferSnapshot, Range<Point>)> {
2911        let mut cursor = self.excerpts.cursor::<Point>(&());
2912        let point = Point::new(row.0, 0);
2913        cursor.seek(&point, Bias::Right, &());
2914        if cursor.item().is_none() && *cursor.start() == point {
2915            cursor.prev(&());
2916        }
2917        if let Some(excerpt) = cursor.item() {
2918            let overshoot = row.0 - cursor.start().row;
2919            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2920            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2921            let buffer_row = excerpt_start.row + overshoot;
2922            let line_start = Point::new(buffer_row, 0);
2923            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2924            return Some((
2925                &excerpt.buffer,
2926                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2927            ));
2928        }
2929        None
2930    }
2931
2932    pub fn max_point(&self) -> Point {
2933        self.text_summary().lines
2934    }
2935
2936    pub fn text_summary(&self) -> TextSummary {
2937        self.excerpts.summary().text.clone()
2938    }
2939
2940    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2941    where
2942        D: TextDimension,
2943        O: ToOffset,
2944    {
2945        let mut summary = D::zero(&());
2946        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2947        let mut cursor = self.excerpts.cursor::<usize>(&());
2948        cursor.seek(&range.start, Bias::Right, &());
2949        if let Some(excerpt) = cursor.item() {
2950            let mut end_before_newline = cursor.end(&());
2951            if excerpt.has_trailing_newline {
2952                end_before_newline -= 1;
2953            }
2954
2955            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2956            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2957            let end_in_excerpt =
2958                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2959            summary.add_assign(
2960                &excerpt
2961                    .buffer
2962                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2963            );
2964
2965            if range.end > end_before_newline {
2966                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2967            }
2968
2969            cursor.next(&());
2970        }
2971
2972        if range.end > *cursor.start() {
2973            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2974                &range.end,
2975                Bias::Right,
2976                &(),
2977            )));
2978            if let Some(excerpt) = cursor.item() {
2979                range.end = cmp::max(*cursor.start(), range.end);
2980
2981                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2982                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2983                summary.add_assign(
2984                    &excerpt
2985                        .buffer
2986                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2987                );
2988            }
2989        }
2990
2991        summary
2992    }
2993
2994    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2995    where
2996        D: TextDimension + Ord + Sub<D, Output = D>,
2997    {
2998        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
2999        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
3000
3001        cursor.seek(locator, Bias::Left, &());
3002        if cursor.item().is_none() {
3003            cursor.next(&());
3004        }
3005
3006        let mut position = D::from_text_summary(&cursor.start().text);
3007        if let Some(excerpt) = cursor.item() {
3008            if excerpt.id == anchor.excerpt_id {
3009                let excerpt_buffer_start =
3010                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
3011                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
3012                let buffer_position = cmp::min(
3013                    excerpt_buffer_end,
3014                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
3015                );
3016                if buffer_position > excerpt_buffer_start {
3017                    position.add_assign(&(buffer_position - excerpt_buffer_start));
3018                }
3019            }
3020        }
3021        position
3022    }
3023
3024    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
3025    where
3026        D: TextDimension + Ord + Sub<D, Output = D>,
3027        I: 'a + IntoIterator<Item = &'a Anchor>,
3028    {
3029        if let Some((_, _, buffer)) = self.as_singleton() {
3030            return buffer
3031                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
3032                .collect();
3033        }
3034
3035        let mut anchors = anchors.into_iter().peekable();
3036        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
3037        let mut summaries = Vec::new();
3038        while let Some(anchor) = anchors.peek() {
3039            let excerpt_id = anchor.excerpt_id;
3040            let excerpt_anchors = iter::from_fn(|| {
3041                let anchor = anchors.peek()?;
3042                if anchor.excerpt_id == excerpt_id {
3043                    Some(&anchors.next().unwrap().text_anchor)
3044                } else {
3045                    None
3046                }
3047            });
3048
3049            let locator = self.excerpt_locator_for_id(excerpt_id);
3050            cursor.seek_forward(locator, Bias::Left, &());
3051            if cursor.item().is_none() {
3052                cursor.next(&());
3053            }
3054
3055            let position = D::from_text_summary(&cursor.start().text);
3056            if let Some(excerpt) = cursor.item() {
3057                if excerpt.id == excerpt_id {
3058                    let excerpt_buffer_start =
3059                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
3060                    let excerpt_buffer_end =
3061                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
3062                    summaries.extend(
3063                        excerpt
3064                            .buffer
3065                            .summaries_for_anchors::<D, _>(excerpt_anchors)
3066                            .map(move |summary| {
3067                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
3068                                let mut position = position.clone();
3069                                let excerpt_buffer_start = excerpt_buffer_start.clone();
3070                                if summary > excerpt_buffer_start {
3071                                    position.add_assign(&(summary - excerpt_buffer_start));
3072                                }
3073                                position
3074                            }),
3075                    );
3076                    continue;
3077                }
3078            }
3079
3080            summaries.extend(excerpt_anchors.map(|_| position.clone()));
3081        }
3082
3083        summaries
3084    }
3085
3086    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
3087    where
3088        I: 'a + IntoIterator<Item = &'a Anchor>,
3089    {
3090        let mut anchors = anchors.into_iter().enumerate().peekable();
3091        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3092        cursor.next(&());
3093
3094        let mut result = Vec::new();
3095
3096        while let Some((_, anchor)) = anchors.peek() {
3097            let old_excerpt_id = anchor.excerpt_id;
3098
3099            // Find the location where this anchor's excerpt should be.
3100            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
3101            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
3102
3103            if cursor.item().is_none() {
3104                cursor.next(&());
3105            }
3106
3107            let next_excerpt = cursor.item();
3108            let prev_excerpt = cursor.prev_item();
3109
3110            // Process all of the anchors for this excerpt.
3111            while let Some((_, anchor)) = anchors.peek() {
3112                if anchor.excerpt_id != old_excerpt_id {
3113                    break;
3114                }
3115                let (anchor_ix, anchor) = anchors.next().unwrap();
3116                let mut anchor = *anchor;
3117
3118                // Leave min and max anchors unchanged if invalid or
3119                // if the old excerpt still exists at this location
3120                let mut kept_position = next_excerpt
3121                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
3122                    || old_excerpt_id == ExcerptId::max()
3123                    || old_excerpt_id == ExcerptId::min();
3124
3125                // If the old excerpt no longer exists at this location, then attempt to
3126                // find an equivalent position for this anchor in an adjacent excerpt.
3127                if !kept_position {
3128                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
3129                        if excerpt.contains(&anchor) {
3130                            anchor.excerpt_id = excerpt.id;
3131                            kept_position = true;
3132                            break;
3133                        }
3134                    }
3135                }
3136
3137                // If there's no adjacent excerpt that contains the anchor's position,
3138                // then report that the anchor has lost its position.
3139                if !kept_position {
3140                    anchor = if let Some(excerpt) = next_excerpt {
3141                        let mut text_anchor = excerpt
3142                            .range
3143                            .context
3144                            .start
3145                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
3146                        if text_anchor
3147                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
3148                            .is_gt()
3149                        {
3150                            text_anchor = excerpt.range.context.end;
3151                        }
3152                        Anchor {
3153                            buffer_id: Some(excerpt.buffer_id),
3154                            excerpt_id: excerpt.id,
3155                            text_anchor,
3156                        }
3157                    } else if let Some(excerpt) = prev_excerpt {
3158                        let mut text_anchor = excerpt
3159                            .range
3160                            .context
3161                            .end
3162                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
3163                        if text_anchor
3164                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
3165                            .is_lt()
3166                        {
3167                            text_anchor = excerpt.range.context.start;
3168                        }
3169                        Anchor {
3170                            buffer_id: Some(excerpt.buffer_id),
3171                            excerpt_id: excerpt.id,
3172                            text_anchor,
3173                        }
3174                    } else if anchor.text_anchor.bias == Bias::Left {
3175                        Anchor::min()
3176                    } else {
3177                        Anchor::max()
3178                    };
3179                }
3180
3181                result.push((anchor_ix, anchor, kept_position));
3182            }
3183        }
3184        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
3185        result
3186    }
3187
3188    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
3189        self.anchor_at(position, Bias::Left)
3190    }
3191
3192    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
3193        self.anchor_at(position, Bias::Right)
3194    }
3195
3196    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
3197        let offset = position.to_offset(self);
3198        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
3199            return Anchor {
3200                buffer_id: Some(buffer_id),
3201                excerpt_id: *excerpt_id,
3202                text_anchor: buffer.anchor_at(offset, bias),
3203            };
3204        }
3205
3206        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>(&());
3207        cursor.seek(&offset, Bias::Right, &());
3208        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
3209            cursor.prev(&());
3210        }
3211        if let Some(excerpt) = cursor.item() {
3212            let mut overshoot = offset.saturating_sub(cursor.start().0);
3213            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
3214                overshoot -= 1;
3215                bias = Bias::Right;
3216            }
3217
3218            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3219            let text_anchor =
3220                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
3221            Anchor {
3222                buffer_id: Some(excerpt.buffer_id),
3223                excerpt_id: excerpt.id,
3224                text_anchor,
3225            }
3226        } else if offset == 0 && bias == Bias::Left {
3227            Anchor::min()
3228        } else {
3229            Anchor::max()
3230        }
3231    }
3232
3233    /// Returns an anchor for the given excerpt and text anchor,
3234    /// returns None if the excerpt_id is no longer valid.
3235    pub fn anchor_in_excerpt(
3236        &self,
3237        excerpt_id: ExcerptId,
3238        text_anchor: text::Anchor,
3239    ) -> Option<Anchor> {
3240        let locator = self.excerpt_locator_for_id(excerpt_id);
3241        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3242        cursor.seek(locator, Bias::Left, &());
3243        if let Some(excerpt) = cursor.item() {
3244            if excerpt.id == excerpt_id {
3245                let text_anchor = excerpt.clip_anchor(text_anchor);
3246                drop(cursor);
3247                return Some(Anchor {
3248                    buffer_id: Some(excerpt.buffer_id),
3249                    excerpt_id,
3250                    text_anchor,
3251                });
3252            }
3253        }
3254        None
3255    }
3256
3257    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
3258        Some(self.excerpt(excerpt_id)?.range.context.clone())
3259    }
3260
3261    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
3262        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
3263            true
3264        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
3265            excerpt.buffer.can_resolve(&anchor.text_anchor)
3266        } else {
3267            false
3268        }
3269    }
3270
3271    pub fn excerpts(
3272        &self,
3273    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
3274        self.excerpts
3275            .iter()
3276            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
3277    }
3278
3279    fn excerpts_for_range<T: ToOffset>(
3280        &self,
3281        range: Range<T>,
3282    ) -> impl Iterator<Item = (&Excerpt, usize)> + '_ {
3283        let range = range.start.to_offset(self)..range.end.to_offset(self);
3284
3285        let mut cursor = self.excerpts.cursor::<usize>(&());
3286        cursor.seek(&range.start, Bias::Right, &());
3287        cursor.prev(&());
3288
3289        iter::from_fn(move || {
3290            cursor.next(&());
3291            if cursor.start() < &range.end {
3292                cursor.item().map(|item| (item, *cursor.start()))
3293            } else {
3294                None
3295            }
3296        })
3297    }
3298
3299    pub fn excerpt_boundaries_in_range<R, T>(
3300        &self,
3301        range: R,
3302    ) -> impl Iterator<Item = ExcerptBoundary> + '_
3303    where
3304        R: RangeBounds<T>,
3305        T: ToOffset,
3306    {
3307        let start_offset;
3308        let start = match range.start_bound() {
3309            Bound::Included(start) => {
3310                start_offset = start.to_offset(self);
3311                Bound::Included(start_offset)
3312            }
3313            Bound::Excluded(start) => {
3314                start_offset = start.to_offset(self);
3315                Bound::Excluded(start_offset)
3316            }
3317            Bound::Unbounded => {
3318                start_offset = 0;
3319                Bound::Unbounded
3320            }
3321        };
3322        let end = match range.end_bound() {
3323            Bound::Included(end) => Bound::Included(end.to_offset(self)),
3324            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
3325            Bound::Unbounded => Bound::Unbounded,
3326        };
3327        let bounds = (start, end);
3328
3329        let mut cursor = self.excerpts.cursor::<(usize, Point)>(&());
3330        cursor.seek(&start_offset, Bias::Right, &());
3331        if cursor.item().is_none() {
3332            cursor.prev(&());
3333        }
3334        if !bounds.contains(&cursor.start().0) {
3335            cursor.next(&());
3336        }
3337
3338        let mut visited_end = false;
3339        std::iter::from_fn(move || {
3340            if self.singleton {
3341                None
3342            } else if bounds.contains(&cursor.start().0) {
3343                let next = cursor.item().map(|excerpt| ExcerptInfo {
3344                    id: excerpt.id,
3345                    buffer: excerpt.buffer.clone(),
3346                    buffer_id: excerpt.buffer_id,
3347                    range: excerpt.range.clone(),
3348                });
3349
3350                if next.is_none() {
3351                    if visited_end {
3352                        return None;
3353                    } else {
3354                        visited_end = true;
3355                    }
3356                }
3357
3358                let prev = cursor.prev_item().map(|prev_excerpt| ExcerptInfo {
3359                    id: prev_excerpt.id,
3360                    buffer: prev_excerpt.buffer.clone(),
3361                    buffer_id: prev_excerpt.buffer_id,
3362                    range: prev_excerpt.range.clone(),
3363                });
3364                let row = MultiBufferRow(cursor.start().1.row);
3365
3366                cursor.next(&());
3367
3368                Some(ExcerptBoundary { row, prev, next })
3369            } else {
3370                None
3371            }
3372        })
3373    }
3374
3375    pub fn edit_count(&self) -> usize {
3376        self.edit_count
3377    }
3378
3379    pub fn non_text_state_update_count(&self) -> usize {
3380        self.non_text_state_update_count
3381    }
3382
3383    /// Returns the smallest enclosing bracket ranges containing the given range or
3384    /// None if no brackets contain range or the range is not contained in a single
3385    /// excerpt
3386    ///
3387    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
3388    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
3389        &self,
3390        range: Range<T>,
3391        range_filter: Option<&dyn Fn(Range<usize>, Range<usize>) -> bool>,
3392    ) -> Option<(Range<usize>, Range<usize>)> {
3393        let range = range.start.to_offset(self)..range.end.to_offset(self);
3394        let excerpt = self.excerpt_containing(range.clone())?;
3395
3396        // Filter to ranges contained in the excerpt
3397        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
3398            excerpt.contains_buffer_range(open.start..close.end)
3399                && range_filter.map_or(true, |filter| {
3400                    filter(
3401                        excerpt.map_range_from_buffer(open),
3402                        excerpt.map_range_from_buffer(close),
3403                    )
3404                })
3405        };
3406
3407        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
3408            excerpt.map_range_to_buffer(range),
3409            Some(&range_filter),
3410        )?;
3411
3412        Some((
3413            excerpt.map_range_from_buffer(open),
3414            excerpt.map_range_from_buffer(close),
3415        ))
3416    }
3417
3418    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
3419    /// not contained in a single excerpt
3420    pub fn enclosing_bracket_ranges<T: ToOffset>(
3421        &self,
3422        range: Range<T>,
3423    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3424        let range = range.start.to_offset(self)..range.end.to_offset(self);
3425        let excerpt = self.excerpt_containing(range.clone())?;
3426
3427        Some(
3428            excerpt
3429                .buffer()
3430                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
3431                .filter_map(move |(open, close)| {
3432                    if excerpt.contains_buffer_range(open.start..close.end) {
3433                        Some((
3434                            excerpt.map_range_from_buffer(open),
3435                            excerpt.map_range_from_buffer(close),
3436                        ))
3437                    } else {
3438                        None
3439                    }
3440                }),
3441        )
3442    }
3443
3444    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
3445    /// not contained in a single excerpt
3446    pub fn bracket_ranges<T: ToOffset>(
3447        &self,
3448        range: Range<T>,
3449    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3450        let range = range.start.to_offset(self)..range.end.to_offset(self);
3451        let excerpt = self.excerpt_containing(range.clone())?;
3452
3453        Some(
3454            excerpt
3455                .buffer()
3456                .bracket_ranges(excerpt.map_range_to_buffer(range))
3457                .filter_map(move |(start_bracket_range, close_bracket_range)| {
3458                    let buffer_range = start_bracket_range.start..close_bracket_range.end;
3459                    if excerpt.contains_buffer_range(buffer_range) {
3460                        Some((
3461                            excerpt.map_range_from_buffer(start_bracket_range),
3462                            excerpt.map_range_from_buffer(close_bracket_range),
3463                        ))
3464                    } else {
3465                        None
3466                    }
3467                }),
3468        )
3469    }
3470
3471    pub fn redacted_ranges<'a, T: ToOffset>(
3472        &'a self,
3473        range: Range<T>,
3474        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
3475    ) -> impl Iterator<Item = Range<usize>> + 'a {
3476        let range = range.start.to_offset(self)..range.end.to_offset(self);
3477        self.excerpts_for_range(range.clone())
3478            .filter(move |&(excerpt, _)| redaction_enabled(excerpt.buffer.file()))
3479            .flat_map(move |(excerpt, excerpt_offset)| {
3480                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3481
3482                excerpt
3483                    .buffer
3484                    .redacted_ranges(excerpt.range.context.clone())
3485                    .map(move |mut redacted_range| {
3486                        // Re-base onto the excerpts coordinates in the multibuffer
3487                        redacted_range.start = excerpt_offset
3488                            + redacted_range.start.saturating_sub(excerpt_buffer_start);
3489                        redacted_range.end = excerpt_offset
3490                            + redacted_range.end.saturating_sub(excerpt_buffer_start);
3491
3492                        redacted_range
3493                    })
3494                    .skip_while(move |redacted_range| redacted_range.end < range.start)
3495                    .take_while(move |redacted_range| redacted_range.start < range.end)
3496            })
3497    }
3498
3499    pub fn runnable_ranges(
3500        &self,
3501        range: Range<Anchor>,
3502    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
3503        let range = range.start.to_offset(self)..range.end.to_offset(self);
3504        self.excerpts_for_range(range.clone())
3505            .flat_map(move |(excerpt, excerpt_offset)| {
3506                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3507
3508                excerpt
3509                    .buffer
3510                    .runnable_ranges(excerpt.range.context.clone())
3511                    .filter_map(move |mut runnable| {
3512                        // Re-base onto the excerpts coordinates in the multibuffer
3513                        //
3514                        // The node matching our runnables query might partially overlap with
3515                        // the provided range. If the run indicator is outside of excerpt bounds, do not actually show it.
3516                        if runnable.run_range.start < excerpt_buffer_start {
3517                            return None;
3518                        }
3519                        if language::ToPoint::to_point(&runnable.run_range.end, &excerpt.buffer).row
3520                            > excerpt.max_buffer_row
3521                        {
3522                            return None;
3523                        }
3524                        runnable.run_range.start =
3525                            excerpt_offset + runnable.run_range.start - excerpt_buffer_start;
3526                        runnable.run_range.end =
3527                            excerpt_offset + runnable.run_range.end - excerpt_buffer_start;
3528                        Some(runnable)
3529                    })
3530                    .skip_while(move |runnable| runnable.run_range.end < range.start)
3531                    .take_while(move |runnable| runnable.run_range.start < range.end)
3532            })
3533    }
3534
3535    pub fn indent_guides_in_range(
3536        &self,
3537        range: Range<Anchor>,
3538        ignore_disabled_for_language: bool,
3539        cx: &AppContext,
3540    ) -> Vec<MultiBufferIndentGuide> {
3541        // Fast path for singleton buffers, we can skip the conversion between offsets.
3542        if let Some((_, _, snapshot)) = self.as_singleton() {
3543            return snapshot
3544                .indent_guides_in_range(
3545                    range.start.text_anchor..range.end.text_anchor,
3546                    ignore_disabled_for_language,
3547                    cx,
3548                )
3549                .into_iter()
3550                .map(|guide| MultiBufferIndentGuide {
3551                    multibuffer_row_range: MultiBufferRow(guide.start_row)
3552                        ..MultiBufferRow(guide.end_row),
3553                    buffer: guide,
3554                })
3555                .collect();
3556        }
3557
3558        let range = range.start.to_offset(self)..range.end.to_offset(self);
3559
3560        self.excerpts_for_range(range.clone())
3561            .flat_map(move |(excerpt, excerpt_offset)| {
3562                let excerpt_buffer_start_row =
3563                    excerpt.range.context.start.to_point(&excerpt.buffer).row;
3564                let excerpt_offset_row = crate::ToPoint::to_point(&excerpt_offset, self).row;
3565
3566                excerpt
3567                    .buffer
3568                    .indent_guides_in_range(
3569                        excerpt.range.context.clone(),
3570                        ignore_disabled_for_language,
3571                        cx,
3572                    )
3573                    .into_iter()
3574                    .map(move |indent_guide| {
3575                        let start_row = excerpt_offset_row
3576                            + (indent_guide.start_row - excerpt_buffer_start_row);
3577                        let end_row =
3578                            excerpt_offset_row + (indent_guide.end_row - excerpt_buffer_start_row);
3579
3580                        MultiBufferIndentGuide {
3581                            multibuffer_row_range: MultiBufferRow(start_row)
3582                                ..MultiBufferRow(end_row),
3583                            buffer: indent_guide,
3584                        }
3585                    })
3586            })
3587            .collect()
3588    }
3589
3590    pub fn trailing_excerpt_update_count(&self) -> usize {
3591        self.trailing_excerpt_update_count
3592    }
3593
3594    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
3595        self.point_to_buffer_offset(point)
3596            .and_then(|(buffer, _)| buffer.file())
3597    }
3598
3599    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
3600        self.point_to_buffer_offset(point)
3601            .and_then(|(buffer, offset)| buffer.language_at(offset))
3602    }
3603
3604    pub fn settings_at<'a, T: ToOffset>(
3605        &'a self,
3606        point: T,
3607        cx: &'a AppContext,
3608    ) -> Cow<'a, LanguageSettings> {
3609        let mut language = None;
3610        let mut file = None;
3611        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
3612            language = buffer.language_at(offset);
3613            file = buffer.file();
3614        }
3615        language_settings(language.map(|l| l.name()), file, cx)
3616    }
3617
3618    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
3619        self.point_to_buffer_offset(point)
3620            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
3621    }
3622
3623    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
3624        self.point_to_buffer_offset(point)
3625            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
3626            .unwrap_or_default()
3627    }
3628
3629    pub fn language_indent_size_at<T: ToOffset>(
3630        &self,
3631        position: T,
3632        cx: &AppContext,
3633    ) -> Option<IndentSize> {
3634        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
3635        Some(buffer_snapshot.language_indent_size_at(offset, cx))
3636    }
3637
3638    pub fn is_dirty(&self) -> bool {
3639        self.is_dirty
3640    }
3641
3642    pub fn has_conflict(&self) -> bool {
3643        self.has_conflict
3644    }
3645
3646    pub fn has_diagnostics(&self) -> bool {
3647        self.excerpts
3648            .iter()
3649            .any(|excerpt| excerpt.buffer.has_diagnostics())
3650    }
3651
3652    pub fn diagnostic_group<'a, O>(
3653        &'a self,
3654        group_id: usize,
3655    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3656    where
3657        O: text::FromAnchor + 'a,
3658    {
3659        self.as_singleton()
3660            .into_iter()
3661            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
3662    }
3663
3664    pub fn diagnostics_in_range<'a, T, O>(
3665        &'a self,
3666        range: Range<T>,
3667        reversed: bool,
3668    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3669    where
3670        T: 'a + ToOffset,
3671        O: 'a + text::FromAnchor + Ord,
3672    {
3673        self.as_singleton()
3674            .into_iter()
3675            .flat_map(move |(_, _, buffer)| {
3676                buffer.diagnostics_in_range(
3677                    range.start.to_offset(self)..range.end.to_offset(self),
3678                    reversed,
3679                )
3680            })
3681    }
3682
3683    pub fn has_git_diffs(&self) -> bool {
3684        for excerpt in self.excerpts.iter() {
3685            if excerpt.buffer.has_git_diff() {
3686                return true;
3687            }
3688        }
3689        false
3690    }
3691
3692    pub fn git_diff_hunks_in_range_rev(
3693        &self,
3694        row_range: Range<MultiBufferRow>,
3695    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3696        let mut cursor = self.excerpts.cursor::<Point>(&());
3697
3698        cursor.seek(&Point::new(row_range.end.0, 0), Bias::Left, &());
3699        if cursor.item().is_none() {
3700            cursor.prev(&());
3701        }
3702
3703        std::iter::from_fn(move || {
3704            let excerpt = cursor.item()?;
3705            let multibuffer_start = *cursor.start();
3706            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3707            if multibuffer_start.row >= row_range.end.0 {
3708                return None;
3709            }
3710
3711            let mut buffer_start = excerpt.range.context.start;
3712            let mut buffer_end = excerpt.range.context.end;
3713            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3714            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3715
3716            if row_range.start.0 > multibuffer_start.row {
3717                let buffer_start_point =
3718                    excerpt_start_point + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3719                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3720            }
3721
3722            if row_range.end.0 < multibuffer_end.row {
3723                let buffer_end_point =
3724                    excerpt_start_point + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3725                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3726            }
3727
3728            let buffer_hunks = excerpt
3729                .buffer
3730                .git_diff_hunks_intersecting_range_rev(buffer_start..buffer_end)
3731                .map(move |hunk| {
3732                    let start = multibuffer_start.row
3733                        + hunk.row_range.start.saturating_sub(excerpt_start_point.row);
3734                    let end = multibuffer_start.row
3735                        + hunk
3736                            .row_range
3737                            .end
3738                            .min(excerpt_end_point.row + 1)
3739                            .saturating_sub(excerpt_start_point.row);
3740
3741                    MultiBufferDiffHunk {
3742                        row_range: MultiBufferRow(start)..MultiBufferRow(end),
3743                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3744                        buffer_range: hunk.buffer_range.clone(),
3745                        buffer_id: excerpt.buffer_id,
3746                    }
3747                });
3748
3749            cursor.prev(&());
3750
3751            Some(buffer_hunks)
3752        })
3753        .flatten()
3754    }
3755
3756    pub fn git_diff_hunks_in_range(
3757        &self,
3758        row_range: Range<MultiBufferRow>,
3759    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
3760        let mut cursor = self.excerpts.cursor::<Point>(&());
3761
3762        cursor.seek(&Point::new(row_range.start.0, 0), Bias::Left, &());
3763
3764        std::iter::from_fn(move || {
3765            let excerpt = cursor.item()?;
3766            let multibuffer_start = *cursor.start();
3767            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3768            let mut buffer_start = excerpt.range.context.start;
3769            let mut buffer_end = excerpt.range.context.end;
3770
3771            let excerpt_rows = match multibuffer_start.row.cmp(&row_range.end.0) {
3772                cmp::Ordering::Less => {
3773                    let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3774                    let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3775
3776                    if row_range.start.0 > multibuffer_start.row {
3777                        let buffer_start_point = excerpt_start_point
3778                            + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3779                        buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3780                    }
3781
3782                    if row_range.end.0 < multibuffer_end.row {
3783                        let buffer_end_point = excerpt_start_point
3784                            + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3785                        buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3786                    }
3787                    excerpt_start_point.row..excerpt_end_point.row
3788                }
3789                cmp::Ordering::Equal if row_range.end.0 == 0 => {
3790                    buffer_end = buffer_start;
3791                    0..0
3792                }
3793                cmp::Ordering::Greater | cmp::Ordering::Equal => return None,
3794            };
3795
3796            let buffer_hunks = excerpt
3797                .buffer
3798                .git_diff_hunks_intersecting_range(buffer_start..buffer_end)
3799                .map(move |hunk| {
3800                    let buffer_range = if excerpt_rows.start == 0 && excerpt_rows.end == 0 {
3801                        MultiBufferRow(0)..MultiBufferRow(1)
3802                    } else {
3803                        let start = multibuffer_start.row
3804                            + hunk.row_range.start.saturating_sub(excerpt_rows.start);
3805                        let end = multibuffer_start.row
3806                            + hunk
3807                                .row_range
3808                                .end
3809                                .min(excerpt_rows.end + 1)
3810                                .saturating_sub(excerpt_rows.start);
3811                        MultiBufferRow(start)..MultiBufferRow(end)
3812                    };
3813                    MultiBufferDiffHunk {
3814                        row_range: buffer_range,
3815                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3816                        buffer_range: hunk.buffer_range.clone(),
3817                        buffer_id: excerpt.buffer_id,
3818                    }
3819                });
3820
3821            cursor.next(&());
3822
3823            Some(buffer_hunks)
3824        })
3825        .flatten()
3826    }
3827
3828    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
3829        let range = range.start.to_offset(self)..range.end.to_offset(self);
3830        let excerpt = self.excerpt_containing(range.clone())?;
3831
3832        let ancestor_buffer_range = excerpt
3833            .buffer()
3834            .range_for_syntax_ancestor(excerpt.map_range_to_buffer(range))?;
3835
3836        Some(excerpt.map_range_from_buffer(ancestor_buffer_range))
3837    }
3838
3839    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
3840        let (excerpt_id, _, buffer) = self.as_singleton()?;
3841        let outline = buffer.outline(theme)?;
3842        Some(Outline::new(
3843            outline
3844                .items
3845                .into_iter()
3846                .flat_map(|item| {
3847                    Some(OutlineItem {
3848                        depth: item.depth,
3849                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
3850                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
3851                        text: item.text,
3852                        highlight_ranges: item.highlight_ranges,
3853                        name_ranges: item.name_ranges,
3854                        body_range: item.body_range.and_then(|body_range| {
3855                            Some(
3856                                self.anchor_in_excerpt(*excerpt_id, body_range.start)?
3857                                    ..self.anchor_in_excerpt(*excerpt_id, body_range.end)?,
3858                            )
3859                        }),
3860                        annotation_range: item.annotation_range.and_then(|annotation_range| {
3861                            Some(
3862                                self.anchor_in_excerpt(*excerpt_id, annotation_range.start)?
3863                                    ..self.anchor_in_excerpt(*excerpt_id, annotation_range.end)?,
3864                            )
3865                        }),
3866                    })
3867                })
3868                .collect(),
3869        ))
3870    }
3871
3872    pub fn symbols_containing<T: ToOffset>(
3873        &self,
3874        offset: T,
3875        theme: Option<&SyntaxTheme>,
3876    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
3877        let anchor = self.anchor_before(offset);
3878        let excerpt_id = anchor.excerpt_id;
3879        let excerpt = self.excerpt(excerpt_id)?;
3880        Some((
3881            excerpt.buffer_id,
3882            excerpt
3883                .buffer
3884                .symbols_containing(anchor.text_anchor, theme)
3885                .into_iter()
3886                .flatten()
3887                .flat_map(|item| {
3888                    Some(OutlineItem {
3889                        depth: item.depth,
3890                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
3891                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
3892                        text: item.text,
3893                        highlight_ranges: item.highlight_ranges,
3894                        name_ranges: item.name_ranges,
3895                        body_range: item.body_range.and_then(|body_range| {
3896                            Some(
3897                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
3898                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
3899                            )
3900                        }),
3901                        annotation_range: item.annotation_range.and_then(|body_range| {
3902                            Some(
3903                                self.anchor_in_excerpt(excerpt_id, body_range.start)?
3904                                    ..self.anchor_in_excerpt(excerpt_id, body_range.end)?,
3905                            )
3906                        }),
3907                    })
3908                })
3909                .collect(),
3910        ))
3911    }
3912
3913    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
3914        if id == ExcerptId::min() {
3915            Locator::min_ref()
3916        } else if id == ExcerptId::max() {
3917            Locator::max_ref()
3918        } else {
3919            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
3920            cursor.seek(&id, Bias::Left, &());
3921            if let Some(entry) = cursor.item() {
3922                if entry.id == id {
3923                    return &entry.locator;
3924                }
3925            }
3926            panic!("invalid excerpt id {:?}", id)
3927        }
3928    }
3929
3930    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
3931    fn excerpt_locators_for_ids(
3932        &self,
3933        ids: impl IntoIterator<Item = ExcerptId>,
3934    ) -> SmallVec<[Locator; 1]> {
3935        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
3936        sorted_ids.sort_unstable();
3937        let mut locators = SmallVec::new();
3938
3939        while sorted_ids.last() == Some(&ExcerptId::max()) {
3940            sorted_ids.pop();
3941            if let Some(mapping) = self.excerpt_ids.last() {
3942                locators.push(mapping.locator.clone());
3943            }
3944        }
3945
3946        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
3947        if sorted_ids.peek() == Some(&ExcerptId::min()) {
3948            sorted_ids.next();
3949            if let Some(mapping) = self.excerpt_ids.first() {
3950                locators.push(mapping.locator.clone());
3951            }
3952        }
3953
3954        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(&());
3955        for id in sorted_ids {
3956            if cursor.seek_forward(&id, Bias::Left, &()) {
3957                locators.push(cursor.item().unwrap().locator.clone());
3958            } else {
3959                panic!("invalid excerpt id {:?}", id);
3960            }
3961        }
3962
3963        locators.sort_unstable();
3964        locators
3965    }
3966
3967    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
3968        Some(self.excerpt(excerpt_id)?.buffer_id)
3969    }
3970
3971    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
3972        Some(&self.excerpt(excerpt_id)?.buffer)
3973    }
3974
3975    pub fn range_for_excerpt<'a, T: sum_tree::Dimension<'a, ExcerptSummary>>(
3976        &'a self,
3977        excerpt_id: ExcerptId,
3978    ) -> Option<Range<T>> {
3979        let mut cursor = self.excerpts.cursor::<(Option<&Locator>, T)>(&());
3980        let locator = self.excerpt_locator_for_id(excerpt_id);
3981        if cursor.seek(&Some(locator), Bias::Left, &()) {
3982            let start = cursor.start().1.clone();
3983            let end = cursor.end(&()).1;
3984            Some(start..end)
3985        } else {
3986            None
3987        }
3988    }
3989
3990    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
3991        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(&());
3992        let locator = self.excerpt_locator_for_id(excerpt_id);
3993        cursor.seek(&Some(locator), Bias::Left, &());
3994        if let Some(excerpt) = cursor.item() {
3995            if excerpt.id == excerpt_id {
3996                return Some(excerpt);
3997            }
3998        }
3999        None
4000    }
4001
4002    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
4003    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
4004        let range = range.start.to_offset(self)..range.end.to_offset(self);
4005
4006        let mut cursor = self.excerpts.cursor::<usize>(&());
4007        cursor.seek(&range.start, Bias::Right, &());
4008        let start_excerpt = cursor.item()?;
4009
4010        if range.start == range.end {
4011            return Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()));
4012        }
4013
4014        cursor.seek(&range.end, Bias::Right, &());
4015        let end_excerpt = cursor.item()?;
4016
4017        if start_excerpt.id == end_excerpt.id {
4018            Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()))
4019        } else {
4020            None
4021        }
4022    }
4023
4024    // Takes an iterator over anchor ranges and returns a new iterator over anchor ranges that don't
4025    // span across excerpt boundaries.
4026    pub fn split_ranges<'a, I>(&'a self, ranges: I) -> impl Iterator<Item = Range<Anchor>> + 'a
4027    where
4028        I: IntoIterator<Item = Range<Anchor>> + 'a,
4029    {
4030        let mut ranges = ranges.into_iter().map(|range| range.to_offset(self));
4031        let mut cursor = self.excerpts.cursor::<usize>(&());
4032        cursor.next(&());
4033        let mut current_range = ranges.next();
4034        iter::from_fn(move || {
4035            let range = current_range.clone()?;
4036            if range.start >= cursor.end(&()) {
4037                cursor.seek_forward(&range.start, Bias::Right, &());
4038                if range.start == self.len() {
4039                    cursor.prev(&());
4040                }
4041            }
4042
4043            let excerpt = cursor.item()?;
4044            let range_start_in_excerpt = cmp::max(range.start, *cursor.start());
4045            let range_end_in_excerpt = if excerpt.has_trailing_newline {
4046                cmp::min(range.end, cursor.end(&()) - 1)
4047            } else {
4048                cmp::min(range.end, cursor.end(&()))
4049            };
4050            let buffer_range = MultiBufferExcerpt::new(excerpt, *cursor.start())
4051                .map_range_to_buffer(range_start_in_excerpt..range_end_in_excerpt);
4052
4053            let subrange_start_anchor = Anchor {
4054                buffer_id: Some(excerpt.buffer_id),
4055                excerpt_id: excerpt.id,
4056                text_anchor: excerpt.buffer.anchor_before(buffer_range.start),
4057            };
4058            let subrange_end_anchor = Anchor {
4059                buffer_id: Some(excerpt.buffer_id),
4060                excerpt_id: excerpt.id,
4061                text_anchor: excerpt.buffer.anchor_after(buffer_range.end),
4062            };
4063
4064            if range.end > cursor.end(&()) {
4065                cursor.next(&());
4066            } else {
4067                current_range = ranges.next();
4068            }
4069
4070            Some(subrange_start_anchor..subrange_end_anchor)
4071        })
4072    }
4073
4074    /// Returns excerpts overlapping the given ranges. If range spans multiple excerpts returns one range for each excerpt
4075    ///
4076    /// The ranges are specified in the coordinate space of the multibuffer, not the individual excerpted buffers.
4077    /// Each returned excerpt's range is in the coordinate space of its source buffer.
4078    pub fn excerpts_in_ranges(
4079        &self,
4080        ranges: impl IntoIterator<Item = Range<Anchor>>,
4081    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, Range<usize>)> {
4082        let mut ranges = ranges.into_iter().map(|range| range.to_offset(self));
4083        let mut cursor = self.excerpts.cursor::<usize>(&());
4084        cursor.next(&());
4085        let mut current_range = ranges.next();
4086        iter::from_fn(move || {
4087            let range = current_range.clone()?;
4088            if range.start >= cursor.end(&()) {
4089                cursor.seek_forward(&range.start, Bias::Right, &());
4090                if range.start == self.len() {
4091                    cursor.prev(&());
4092                }
4093            }
4094
4095            let excerpt = cursor.item()?;
4096            let range_start_in_excerpt = cmp::max(range.start, *cursor.start());
4097            let range_end_in_excerpt = if excerpt.has_trailing_newline {
4098                cmp::min(range.end, cursor.end(&()) - 1)
4099            } else {
4100                cmp::min(range.end, cursor.end(&()))
4101            };
4102            let buffer_range = MultiBufferExcerpt::new(excerpt, *cursor.start())
4103                .map_range_to_buffer(range_start_in_excerpt..range_end_in_excerpt);
4104
4105            if range.end > cursor.end(&()) {
4106                cursor.next(&());
4107            } else {
4108                current_range = ranges.next();
4109            }
4110
4111            Some((excerpt.id, &excerpt.buffer, buffer_range))
4112        })
4113    }
4114
4115    pub fn selections_in_range<'a>(
4116        &'a self,
4117        range: &'a Range<Anchor>,
4118        include_local: bool,
4119    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
4120        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(&());
4121        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
4122        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
4123        cursor.seek(start_locator, Bias::Left, &());
4124        cursor
4125            .take_while(move |excerpt| excerpt.locator <= *end_locator)
4126            .flat_map(move |excerpt| {
4127                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
4128                if excerpt.id == range.start.excerpt_id {
4129                    query_range.start = range.start.text_anchor;
4130                }
4131                if excerpt.id == range.end.excerpt_id {
4132                    query_range.end = range.end.text_anchor;
4133                }
4134
4135                excerpt
4136                    .buffer
4137                    .selections_in_range(query_range, include_local)
4138                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
4139                        selections.map(move |selection| {
4140                            let mut start = Anchor {
4141                                buffer_id: Some(excerpt.buffer_id),
4142                                excerpt_id: excerpt.id,
4143                                text_anchor: selection.start,
4144                            };
4145                            let mut end = Anchor {
4146                                buffer_id: Some(excerpt.buffer_id),
4147                                excerpt_id: excerpt.id,
4148                                text_anchor: selection.end,
4149                            };
4150                            if range.start.cmp(&start, self).is_gt() {
4151                                start = range.start;
4152                            }
4153                            if range.end.cmp(&end, self).is_lt() {
4154                                end = range.end;
4155                            }
4156
4157                            (
4158                                replica_id,
4159                                line_mode,
4160                                cursor_shape,
4161                                Selection {
4162                                    id: selection.id,
4163                                    start,
4164                                    end,
4165                                    reversed: selection.reversed,
4166                                    goal: selection.goal,
4167                                },
4168                            )
4169                        })
4170                    })
4171            })
4172    }
4173
4174    pub fn show_headers(&self) -> bool {
4175        self.show_headers
4176    }
4177}
4178
4179#[cfg(any(test, feature = "test-support"))]
4180impl MultiBufferSnapshot {
4181    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
4182        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
4183        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
4184        start..end
4185    }
4186}
4187
4188impl History {
4189    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
4190        self.transaction_depth += 1;
4191        if self.transaction_depth == 1 {
4192            let id = self.next_transaction_id.tick();
4193            self.undo_stack.push(Transaction {
4194                id,
4195                buffer_transactions: Default::default(),
4196                first_edit_at: now,
4197                last_edit_at: now,
4198                suppress_grouping: false,
4199            });
4200            Some(id)
4201        } else {
4202            None
4203        }
4204    }
4205
4206    fn end_transaction(
4207        &mut self,
4208        now: Instant,
4209        buffer_transactions: HashMap<BufferId, TransactionId>,
4210    ) -> bool {
4211        assert_ne!(self.transaction_depth, 0);
4212        self.transaction_depth -= 1;
4213        if self.transaction_depth == 0 {
4214            if buffer_transactions.is_empty() {
4215                self.undo_stack.pop();
4216                false
4217            } else {
4218                self.redo_stack.clear();
4219                let transaction = self.undo_stack.last_mut().unwrap();
4220                transaction.last_edit_at = now;
4221                for (buffer_id, transaction_id) in buffer_transactions {
4222                    transaction
4223                        .buffer_transactions
4224                        .entry(buffer_id)
4225                        .or_insert(transaction_id);
4226                }
4227                true
4228            }
4229        } else {
4230            false
4231        }
4232    }
4233
4234    fn push_transaction<'a, T>(
4235        &mut self,
4236        buffer_transactions: T,
4237        now: Instant,
4238        cx: &ModelContext<MultiBuffer>,
4239    ) where
4240        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
4241    {
4242        assert_eq!(self.transaction_depth, 0);
4243        let transaction = Transaction {
4244            id: self.next_transaction_id.tick(),
4245            buffer_transactions: buffer_transactions
4246                .into_iter()
4247                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
4248                .collect(),
4249            first_edit_at: now,
4250            last_edit_at: now,
4251            suppress_grouping: false,
4252        };
4253        if !transaction.buffer_transactions.is_empty() {
4254            self.undo_stack.push(transaction);
4255            self.redo_stack.clear();
4256        }
4257    }
4258
4259    fn finalize_last_transaction(&mut self) {
4260        if let Some(transaction) = self.undo_stack.last_mut() {
4261            transaction.suppress_grouping = true;
4262        }
4263    }
4264
4265    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
4266        if let Some(ix) = self
4267            .undo_stack
4268            .iter()
4269            .rposition(|transaction| transaction.id == transaction_id)
4270        {
4271            Some(self.undo_stack.remove(ix))
4272        } else if let Some(ix) = self
4273            .redo_stack
4274            .iter()
4275            .rposition(|transaction| transaction.id == transaction_id)
4276        {
4277            Some(self.redo_stack.remove(ix))
4278        } else {
4279            None
4280        }
4281    }
4282
4283    fn transaction(&self, transaction_id: TransactionId) -> Option<&Transaction> {
4284        self.undo_stack
4285            .iter()
4286            .find(|transaction| transaction.id == transaction_id)
4287            .or_else(|| {
4288                self.redo_stack
4289                    .iter()
4290                    .find(|transaction| transaction.id == transaction_id)
4291            })
4292    }
4293
4294    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
4295        self.undo_stack
4296            .iter_mut()
4297            .find(|transaction| transaction.id == transaction_id)
4298            .or_else(|| {
4299                self.redo_stack
4300                    .iter_mut()
4301                    .find(|transaction| transaction.id == transaction_id)
4302            })
4303    }
4304
4305    fn pop_undo(&mut self) -> Option<&mut Transaction> {
4306        assert_eq!(self.transaction_depth, 0);
4307        if let Some(transaction) = self.undo_stack.pop() {
4308            self.redo_stack.push(transaction);
4309            self.redo_stack.last_mut()
4310        } else {
4311            None
4312        }
4313    }
4314
4315    fn pop_redo(&mut self) -> Option<&mut Transaction> {
4316        assert_eq!(self.transaction_depth, 0);
4317        if let Some(transaction) = self.redo_stack.pop() {
4318            self.undo_stack.push(transaction);
4319            self.undo_stack.last_mut()
4320        } else {
4321            None
4322        }
4323    }
4324
4325    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
4326        let ix = self
4327            .undo_stack
4328            .iter()
4329            .rposition(|transaction| transaction.id == transaction_id)?;
4330        let transaction = self.undo_stack.remove(ix);
4331        self.redo_stack.push(transaction);
4332        self.redo_stack.last()
4333    }
4334
4335    fn group(&mut self) -> Option<TransactionId> {
4336        let mut count = 0;
4337        let mut transactions = self.undo_stack.iter();
4338        if let Some(mut transaction) = transactions.next_back() {
4339            while let Some(prev_transaction) = transactions.next_back() {
4340                if !prev_transaction.suppress_grouping
4341                    && transaction.first_edit_at - prev_transaction.last_edit_at
4342                        <= self.group_interval
4343                {
4344                    transaction = prev_transaction;
4345                    count += 1;
4346                } else {
4347                    break;
4348                }
4349            }
4350        }
4351        self.group_trailing(count)
4352    }
4353
4354    fn group_until(&mut self, transaction_id: TransactionId) {
4355        let mut count = 0;
4356        for transaction in self.undo_stack.iter().rev() {
4357            if transaction.id == transaction_id {
4358                self.group_trailing(count);
4359                break;
4360            } else if transaction.suppress_grouping {
4361                break;
4362            } else {
4363                count += 1;
4364            }
4365        }
4366    }
4367
4368    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
4369        let new_len = self.undo_stack.len() - n;
4370        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
4371        if let Some(last_transaction) = transactions_to_keep.last_mut() {
4372            if let Some(transaction) = transactions_to_merge.last() {
4373                last_transaction.last_edit_at = transaction.last_edit_at;
4374            }
4375            for to_merge in transactions_to_merge {
4376                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
4377                    last_transaction
4378                        .buffer_transactions
4379                        .entry(*buffer_id)
4380                        .or_insert(*transaction_id);
4381                }
4382            }
4383        }
4384
4385        self.undo_stack.truncate(new_len);
4386        self.undo_stack.last().map(|t| t.id)
4387    }
4388}
4389
4390impl Excerpt {
4391    fn new(
4392        id: ExcerptId,
4393        locator: Locator,
4394        buffer_id: BufferId,
4395        buffer: BufferSnapshot,
4396        range: ExcerptRange<text::Anchor>,
4397        has_trailing_newline: bool,
4398    ) -> Self {
4399        Excerpt {
4400            id,
4401            locator,
4402            max_buffer_row: range.context.end.to_point(&buffer).row,
4403            text_summary: buffer
4404                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
4405            buffer_id,
4406            buffer,
4407            range,
4408            has_trailing_newline,
4409        }
4410    }
4411
4412    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
4413        let content_start = self.range.context.start.to_offset(&self.buffer);
4414        let chunks_start = content_start + range.start;
4415        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
4416
4417        let footer_height = if self.has_trailing_newline
4418            && range.start <= self.text_summary.len
4419            && range.end > self.text_summary.len
4420        {
4421            1
4422        } else {
4423            0
4424        };
4425
4426        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
4427
4428        ExcerptChunks {
4429            excerpt_id: self.id,
4430            content_chunks,
4431            footer_height,
4432        }
4433    }
4434
4435    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
4436        let content_start = self.range.context.start.to_offset(&self.buffer);
4437        let chunks_start = content_start + range.start;
4438        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
4439        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
4440        excerpt_chunks.footer_height = if self.has_trailing_newline
4441            && range.start <= self.text_summary.len
4442            && range.end > self.text_summary.len
4443        {
4444            1
4445        } else {
4446            0
4447        };
4448    }
4449
4450    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
4451        let content_start = self.range.context.start.to_offset(&self.buffer);
4452        let bytes_start = content_start + range.start;
4453        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
4454        let footer_height = if self.has_trailing_newline
4455            && range.start <= self.text_summary.len
4456            && range.end > self.text_summary.len
4457        {
4458            1
4459        } else {
4460            0
4461        };
4462        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
4463
4464        ExcerptBytes {
4465            content_bytes,
4466            padding_height: footer_height,
4467            reversed: false,
4468        }
4469    }
4470
4471    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
4472        let content_start = self.range.context.start.to_offset(&self.buffer);
4473        let bytes_start = content_start + range.start;
4474        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
4475        let footer_height = if self.has_trailing_newline
4476            && range.start <= self.text_summary.len
4477            && range.end > self.text_summary.len
4478        {
4479            1
4480        } else {
4481            0
4482        };
4483        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
4484
4485        ExcerptBytes {
4486            content_bytes,
4487            padding_height: footer_height,
4488            reversed: true,
4489        }
4490    }
4491
4492    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
4493        if text_anchor
4494            .cmp(&self.range.context.start, &self.buffer)
4495            .is_lt()
4496        {
4497            self.range.context.start
4498        } else if text_anchor
4499            .cmp(&self.range.context.end, &self.buffer)
4500            .is_gt()
4501        {
4502            self.range.context.end
4503        } else {
4504            text_anchor
4505        }
4506    }
4507
4508    fn contains(&self, anchor: &Anchor) -> bool {
4509        Some(self.buffer_id) == anchor.buffer_id
4510            && self
4511                .range
4512                .context
4513                .start
4514                .cmp(&anchor.text_anchor, &self.buffer)
4515                .is_le()
4516            && self
4517                .range
4518                .context
4519                .end
4520                .cmp(&anchor.text_anchor, &self.buffer)
4521                .is_ge()
4522    }
4523
4524    /// The [`Excerpt`]'s start offset in its [`Buffer`]
4525    fn buffer_start_offset(&self) -> usize {
4526        self.range.context.start.to_offset(&self.buffer)
4527    }
4528
4529    /// The [`Excerpt`]'s end offset in its [`Buffer`]
4530    fn buffer_end_offset(&self) -> usize {
4531        self.buffer_start_offset() + self.text_summary.len
4532    }
4533}
4534
4535impl<'a> MultiBufferExcerpt<'a> {
4536    fn new(excerpt: &'a Excerpt, excerpt_offset: usize) -> Self {
4537        MultiBufferExcerpt {
4538            excerpt,
4539            excerpt_offset,
4540        }
4541    }
4542
4543    pub fn buffer(&self) -> &'a BufferSnapshot {
4544        &self.excerpt.buffer
4545    }
4546
4547    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
4548    pub fn map_offset_to_buffer(&self, offset: usize) -> usize {
4549        self.excerpt.buffer_start_offset() + offset.saturating_sub(self.excerpt_offset)
4550    }
4551
4552    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
4553    pub fn map_range_to_buffer(&self, range: Range<usize>) -> Range<usize> {
4554        self.map_offset_to_buffer(range.start)..self.map_offset_to_buffer(range.end)
4555    }
4556
4557    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
4558    pub fn map_offset_from_buffer(&self, buffer_offset: usize) -> usize {
4559        let mut buffer_offset_in_excerpt =
4560            buffer_offset.saturating_sub(self.excerpt.buffer_start_offset());
4561        buffer_offset_in_excerpt =
4562            cmp::min(buffer_offset_in_excerpt, self.excerpt.text_summary.len);
4563
4564        self.excerpt_offset + buffer_offset_in_excerpt
4565    }
4566
4567    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
4568    pub fn map_range_from_buffer(&self, buffer_range: Range<usize>) -> Range<usize> {
4569        self.map_offset_from_buffer(buffer_range.start)
4570            ..self.map_offset_from_buffer(buffer_range.end)
4571    }
4572
4573    /// Returns true if the entirety of the given range is in the buffer's excerpt
4574    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
4575        range.start >= self.excerpt.buffer_start_offset()
4576            && range.end <= self.excerpt.buffer_end_offset()
4577    }
4578}
4579
4580impl ExcerptId {
4581    pub fn min() -> Self {
4582        Self(0)
4583    }
4584
4585    pub fn max() -> Self {
4586        Self(usize::MAX)
4587    }
4588
4589    pub fn to_proto(&self) -> u64 {
4590        self.0 as _
4591    }
4592
4593    pub fn from_proto(proto: u64) -> Self {
4594        Self(proto as _)
4595    }
4596
4597    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
4598        let a = snapshot.excerpt_locator_for_id(*self);
4599        let b = snapshot.excerpt_locator_for_id(*other);
4600        a.cmp(b).then_with(|| self.0.cmp(&other.0))
4601    }
4602}
4603
4604impl From<ExcerptId> for usize {
4605    fn from(val: ExcerptId) -> Self {
4606        val.0
4607    }
4608}
4609
4610impl fmt::Debug for Excerpt {
4611    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4612        f.debug_struct("Excerpt")
4613            .field("id", &self.id)
4614            .field("locator", &self.locator)
4615            .field("buffer_id", &self.buffer_id)
4616            .field("range", &self.range)
4617            .field("text_summary", &self.text_summary)
4618            .field("has_trailing_newline", &self.has_trailing_newline)
4619            .finish()
4620    }
4621}
4622
4623impl sum_tree::Item for Excerpt {
4624    type Summary = ExcerptSummary;
4625
4626    fn summary(&self, _cx: &()) -> Self::Summary {
4627        let mut text = self.text_summary.clone();
4628        if self.has_trailing_newline {
4629            text += TextSummary::from("\n");
4630        }
4631        ExcerptSummary {
4632            excerpt_id: self.id,
4633            excerpt_locator: self.locator.clone(),
4634            max_buffer_row: MultiBufferRow(self.max_buffer_row),
4635            text,
4636        }
4637    }
4638}
4639
4640impl sum_tree::Item for ExcerptIdMapping {
4641    type Summary = ExcerptId;
4642
4643    fn summary(&self, _cx: &()) -> Self::Summary {
4644        self.id
4645    }
4646}
4647
4648impl sum_tree::KeyedItem for ExcerptIdMapping {
4649    type Key = ExcerptId;
4650
4651    fn key(&self) -> Self::Key {
4652        self.id
4653    }
4654}
4655
4656impl sum_tree::Summary for ExcerptId {
4657    type Context = ();
4658
4659    fn zero(_cx: &()) -> Self {
4660        Default::default()
4661    }
4662
4663    fn add_summary(&mut self, other: &Self, _: &()) {
4664        *self = *other;
4665    }
4666}
4667
4668impl sum_tree::Summary for ExcerptSummary {
4669    type Context = ();
4670
4671    fn zero(_cx: &()) -> Self {
4672        Default::default()
4673    }
4674
4675    fn add_summary(&mut self, summary: &Self, _: &()) {
4676        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
4677        self.excerpt_locator = summary.excerpt_locator.clone();
4678        self.text.add_summary(&summary.text, &());
4679        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
4680    }
4681}
4682
4683impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
4684    fn zero(_cx: &()) -> Self {
4685        Default::default()
4686    }
4687
4688    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4689        *self += &summary.text;
4690    }
4691}
4692
4693impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
4694    fn zero(_cx: &()) -> Self {
4695        Default::default()
4696    }
4697
4698    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4699        *self += summary.text.len;
4700    }
4701}
4702
4703impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
4704    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4705        Ord::cmp(self, &cursor_location.text.len)
4706    }
4707}
4708
4709impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
4710    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
4711        Ord::cmp(&Some(self), cursor_location)
4712    }
4713}
4714
4715impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
4716    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4717        Ord::cmp(self, &cursor_location.excerpt_locator)
4718    }
4719}
4720
4721impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
4722    fn zero(_cx: &()) -> Self {
4723        Default::default()
4724    }
4725
4726    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4727        *self += summary.text.len_utf16;
4728    }
4729}
4730
4731impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
4732    fn zero(_cx: &()) -> Self {
4733        Default::default()
4734    }
4735
4736    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4737        *self += summary.text.lines;
4738    }
4739}
4740
4741impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
4742    fn zero(_cx: &()) -> Self {
4743        Default::default()
4744    }
4745
4746    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4747        *self += summary.text.lines_utf16()
4748    }
4749}
4750
4751impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
4752    fn zero(_cx: &()) -> Self {
4753        Default::default()
4754    }
4755
4756    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4757        *self = Some(&summary.excerpt_locator);
4758    }
4759}
4760
4761impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
4762    fn zero(_cx: &()) -> Self {
4763        Default::default()
4764    }
4765
4766    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4767        *self = Some(summary.excerpt_id);
4768    }
4769}
4770
4771impl<'a> MultiBufferRows<'a> {
4772    pub fn seek(&mut self, row: MultiBufferRow) {
4773        self.buffer_row_range = 0..0;
4774
4775        self.excerpts
4776            .seek_forward(&Point::new(row.0, 0), Bias::Right, &());
4777        if self.excerpts.item().is_none() {
4778            self.excerpts.prev(&());
4779
4780            if self.excerpts.item().is_none() && row.0 == 0 {
4781                self.buffer_row_range = 0..1;
4782                return;
4783            }
4784        }
4785
4786        if let Some(excerpt) = self.excerpts.item() {
4787            let overshoot = row.0 - self.excerpts.start().row;
4788            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4789            self.buffer_row_range.start = excerpt_start + overshoot;
4790            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
4791        }
4792    }
4793}
4794
4795impl<'a> Iterator for MultiBufferRows<'a> {
4796    type Item = Option<u32>;
4797
4798    fn next(&mut self) -> Option<Self::Item> {
4799        loop {
4800            if !self.buffer_row_range.is_empty() {
4801                let row = Some(self.buffer_row_range.start);
4802                self.buffer_row_range.start += 1;
4803                return Some(row);
4804            }
4805            self.excerpts.item()?;
4806            self.excerpts.next(&());
4807            let excerpt = self.excerpts.item()?;
4808            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4809            self.buffer_row_range.end =
4810                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
4811        }
4812    }
4813}
4814
4815impl<'a> MultiBufferChunks<'a> {
4816    pub fn offset(&self) -> usize {
4817        self.range.start
4818    }
4819
4820    pub fn seek(&mut self, new_range: Range<usize>) {
4821        self.range = new_range.clone();
4822        self.excerpts.seek(&new_range.start, Bias::Right, &());
4823        if let Some(excerpt) = self.excerpts.item() {
4824            let excerpt_start = self.excerpts.start();
4825            if let Some(excerpt_chunks) = self
4826                .excerpt_chunks
4827                .as_mut()
4828                .filter(|chunks| excerpt.id == chunks.excerpt_id)
4829            {
4830                excerpt.seek_chunks(
4831                    excerpt_chunks,
4832                    self.range.start - excerpt_start..self.range.end - excerpt_start,
4833                );
4834            } else {
4835                self.excerpt_chunks = Some(excerpt.chunks_in_range(
4836                    self.range.start - excerpt_start..self.range.end - excerpt_start,
4837                    self.language_aware,
4838                ));
4839            }
4840        } else {
4841            self.excerpt_chunks = None;
4842        }
4843    }
4844}
4845
4846impl<'a> Iterator for MultiBufferChunks<'a> {
4847    type Item = Chunk<'a>;
4848
4849    fn next(&mut self) -> Option<Self::Item> {
4850        if self.range.is_empty() {
4851            None
4852        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
4853            self.range.start += chunk.text.len();
4854            Some(chunk)
4855        } else {
4856            self.excerpts.next(&());
4857            let excerpt = self.excerpts.item()?;
4858            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4859                0..self.range.end - self.excerpts.start(),
4860                self.language_aware,
4861            ));
4862            self.next()
4863        }
4864    }
4865}
4866
4867impl<'a> MultiBufferBytes<'a> {
4868    fn consume(&mut self, len: usize) {
4869        self.range.start += len;
4870        self.chunk = &self.chunk[len..];
4871
4872        if !self.range.is_empty() && self.chunk.is_empty() {
4873            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4874                self.chunk = chunk;
4875            } else {
4876                self.excerpts.next(&());
4877                if let Some(excerpt) = self.excerpts.item() {
4878                    let mut excerpt_bytes =
4879                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4880                    self.chunk = excerpt_bytes.next().unwrap();
4881                    self.excerpt_bytes = Some(excerpt_bytes);
4882                }
4883            }
4884        }
4885    }
4886}
4887
4888impl<'a> Iterator for MultiBufferBytes<'a> {
4889    type Item = &'a [u8];
4890
4891    fn next(&mut self) -> Option<Self::Item> {
4892        let chunk = self.chunk;
4893        if chunk.is_empty() {
4894            None
4895        } else {
4896            self.consume(chunk.len());
4897            Some(chunk)
4898        }
4899    }
4900}
4901
4902impl<'a> io::Read for MultiBufferBytes<'a> {
4903    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4904        let len = cmp::min(buf.len(), self.chunk.len());
4905        buf[..len].copy_from_slice(&self.chunk[..len]);
4906        if len > 0 {
4907            self.consume(len);
4908        }
4909        Ok(len)
4910    }
4911}
4912
4913impl<'a> ReversedMultiBufferBytes<'a> {
4914    fn consume(&mut self, len: usize) {
4915        self.range.end -= len;
4916        self.chunk = &self.chunk[..self.chunk.len() - len];
4917
4918        if !self.range.is_empty() && self.chunk.is_empty() {
4919            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4920                self.chunk = chunk;
4921            } else {
4922                self.excerpts.prev(&());
4923                if let Some(excerpt) = self.excerpts.item() {
4924                    let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
4925                        self.range.start.saturating_sub(*self.excerpts.start())..usize::MAX,
4926                    );
4927                    self.chunk = excerpt_bytes.next().unwrap();
4928                    self.excerpt_bytes = Some(excerpt_bytes);
4929                }
4930            }
4931        }
4932    }
4933}
4934
4935impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
4936    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4937        let len = cmp::min(buf.len(), self.chunk.len());
4938        buf[..len].copy_from_slice(&self.chunk[..len]);
4939        buf[..len].reverse();
4940        if len > 0 {
4941            self.consume(len);
4942        }
4943        Ok(len)
4944    }
4945}
4946impl<'a> Iterator for ExcerptBytes<'a> {
4947    type Item = &'a [u8];
4948
4949    fn next(&mut self) -> Option<Self::Item> {
4950        if self.reversed && self.padding_height > 0 {
4951            let result = &NEWLINES[..self.padding_height];
4952            self.padding_height = 0;
4953            return Some(result);
4954        }
4955
4956        if let Some(chunk) = self.content_bytes.next() {
4957            if !chunk.is_empty() {
4958                return Some(chunk);
4959            }
4960        }
4961
4962        if self.padding_height > 0 {
4963            let result = &NEWLINES[..self.padding_height];
4964            self.padding_height = 0;
4965            return Some(result);
4966        }
4967
4968        None
4969    }
4970}
4971
4972impl<'a> Iterator for ExcerptChunks<'a> {
4973    type Item = Chunk<'a>;
4974
4975    fn next(&mut self) -> Option<Self::Item> {
4976        if let Some(chunk) = self.content_chunks.next() {
4977            return Some(chunk);
4978        }
4979
4980        if self.footer_height > 0 {
4981            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
4982            self.footer_height = 0;
4983            return Some(Chunk {
4984                text,
4985                ..Default::default()
4986            });
4987        }
4988
4989        None
4990    }
4991}
4992
4993impl ToOffset for Point {
4994    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4995        snapshot.point_to_offset(*self)
4996    }
4997}
4998
4999impl ToOffset for usize {
5000    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
5001        assert!(*self <= snapshot.len(), "offset is out of range");
5002        *self
5003    }
5004}
5005
5006impl ToOffset for OffsetUtf16 {
5007    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
5008        snapshot.offset_utf16_to_offset(*self)
5009    }
5010}
5011
5012impl ToOffset for PointUtf16 {
5013    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
5014        snapshot.point_utf16_to_offset(*self)
5015    }
5016}
5017
5018impl ToOffsetUtf16 for OffsetUtf16 {
5019    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
5020        *self
5021    }
5022}
5023
5024impl ToOffsetUtf16 for usize {
5025    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
5026        snapshot.offset_to_offset_utf16(*self)
5027    }
5028}
5029
5030impl ToPoint for usize {
5031    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
5032        snapshot.offset_to_point(*self)
5033    }
5034}
5035
5036impl ToPoint for Point {
5037    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
5038        *self
5039    }
5040}
5041
5042impl ToPointUtf16 for usize {
5043    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
5044        snapshot.offset_to_point_utf16(*self)
5045    }
5046}
5047
5048impl ToPointUtf16 for Point {
5049    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
5050        snapshot.point_to_point_utf16(*self)
5051    }
5052}
5053
5054impl ToPointUtf16 for PointUtf16 {
5055    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
5056        *self
5057    }
5058}
5059
5060pub fn build_excerpt_ranges<T>(
5061    buffer: &BufferSnapshot,
5062    ranges: &[Range<T>],
5063    context_line_count: u32,
5064) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
5065where
5066    T: text::ToPoint,
5067{
5068    let max_point = buffer.max_point();
5069    let mut range_counts = Vec::new();
5070    let mut excerpt_ranges = Vec::new();
5071    let mut range_iter = ranges
5072        .iter()
5073        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
5074        .peekable();
5075    while let Some(range) = range_iter.next() {
5076        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
5077        let row = (range.end.row + context_line_count).min(max_point.row);
5078        let mut excerpt_end = Point::new(row, buffer.line_len(row));
5079
5080        let mut ranges_in_excerpt = 1;
5081
5082        while let Some(next_range) = range_iter.peek() {
5083            if next_range.start.row <= excerpt_end.row + context_line_count {
5084                let row = (next_range.end.row + context_line_count).min(max_point.row);
5085                excerpt_end = Point::new(row, buffer.line_len(row));
5086
5087                ranges_in_excerpt += 1;
5088                range_iter.next();
5089            } else {
5090                break;
5091            }
5092        }
5093
5094        excerpt_ranges.push(ExcerptRange {
5095            context: excerpt_start..excerpt_end,
5096            primary: Some(range),
5097        });
5098        range_counts.push(ranges_in_excerpt);
5099    }
5100
5101    (excerpt_ranges, range_counts)
5102}
5103
5104#[cfg(test)]
5105mod tests {
5106    use super::*;
5107    use gpui::{AppContext, Context, TestAppContext};
5108    use language::{Buffer, Rope};
5109    use parking_lot::RwLock;
5110    use rand::prelude::*;
5111    use settings::SettingsStore;
5112    use std::env;
5113    use util::test::sample_text;
5114
5115    #[ctor::ctor]
5116    fn init_logger() {
5117        if std::env::var("RUST_LOG").is_ok() {
5118            env_logger::init();
5119        }
5120    }
5121
5122    #[gpui::test]
5123    fn test_singleton(cx: &mut AppContext) {
5124        let buffer = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
5125        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
5126
5127        let snapshot = multibuffer.read(cx).snapshot(cx);
5128        assert_eq!(snapshot.text(), buffer.read(cx).text());
5129
5130        assert_eq!(
5131            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5132            (0..buffer.read(cx).row_count())
5133                .map(Some)
5134                .collect::<Vec<_>>()
5135        );
5136
5137        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
5138        let snapshot = multibuffer.read(cx).snapshot(cx);
5139
5140        assert_eq!(snapshot.text(), buffer.read(cx).text());
5141        assert_eq!(
5142            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5143            (0..buffer.read(cx).row_count())
5144                .map(Some)
5145                .collect::<Vec<_>>()
5146        );
5147    }
5148
5149    #[gpui::test]
5150    fn test_remote(cx: &mut AppContext) {
5151        let host_buffer = cx.new_model(|cx| Buffer::local("a", cx));
5152        let guest_buffer = cx.new_model(|cx| {
5153            let state = host_buffer.read(cx).to_proto(cx);
5154            let ops = cx
5155                .background_executor()
5156                .block(host_buffer.read(cx).serialize_ops(None, cx));
5157            let mut buffer = Buffer::from_proto(1, Capability::ReadWrite, state, None).unwrap();
5158            buffer.apply_ops(
5159                ops.into_iter()
5160                    .map(|op| language::proto::deserialize_operation(op).unwrap()),
5161                cx,
5162            );
5163            buffer
5164        });
5165        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
5166        let snapshot = multibuffer.read(cx).snapshot(cx);
5167        assert_eq!(snapshot.text(), "a");
5168
5169        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
5170        let snapshot = multibuffer.read(cx).snapshot(cx);
5171        assert_eq!(snapshot.text(), "ab");
5172
5173        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
5174        let snapshot = multibuffer.read(cx).snapshot(cx);
5175        assert_eq!(snapshot.text(), "abc");
5176    }
5177
5178    #[gpui::test]
5179    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
5180        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
5181        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
5182        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5183
5184        let events = Arc::new(RwLock::new(Vec::<Event>::new()));
5185        multibuffer.update(cx, |_, cx| {
5186            let events = events.clone();
5187            cx.subscribe(&multibuffer, move |_, _, event, _| {
5188                if let Event::Edited { .. } = event {
5189                    events.write().push(event.clone())
5190                }
5191            })
5192            .detach();
5193        });
5194
5195        let subscription = multibuffer.update(cx, |multibuffer, cx| {
5196            let subscription = multibuffer.subscribe();
5197            multibuffer.push_excerpts(
5198                buffer_1.clone(),
5199                [ExcerptRange {
5200                    context: Point::new(1, 2)..Point::new(2, 5),
5201                    primary: None,
5202                }],
5203                cx,
5204            );
5205            assert_eq!(
5206                subscription.consume().into_inner(),
5207                [Edit {
5208                    old: 0..0,
5209                    new: 0..10
5210                }]
5211            );
5212
5213            multibuffer.push_excerpts(
5214                buffer_1.clone(),
5215                [ExcerptRange {
5216                    context: Point::new(3, 3)..Point::new(4, 4),
5217                    primary: None,
5218                }],
5219                cx,
5220            );
5221            multibuffer.push_excerpts(
5222                buffer_2.clone(),
5223                [ExcerptRange {
5224                    context: Point::new(3, 1)..Point::new(3, 3),
5225                    primary: None,
5226                }],
5227                cx,
5228            );
5229            assert_eq!(
5230                subscription.consume().into_inner(),
5231                [Edit {
5232                    old: 10..10,
5233                    new: 10..22
5234                }]
5235            );
5236
5237            subscription
5238        });
5239
5240        // Adding excerpts emits an edited event.
5241        assert_eq!(
5242            events.read().as_slice(),
5243            &[
5244                Event::Edited {
5245                    singleton_buffer_edited: false
5246                },
5247                Event::Edited {
5248                    singleton_buffer_edited: false
5249                },
5250                Event::Edited {
5251                    singleton_buffer_edited: false
5252                }
5253            ]
5254        );
5255
5256        let snapshot = multibuffer.read(cx).snapshot(cx);
5257        assert_eq!(
5258            snapshot.text(),
5259            concat!(
5260                "bbbb\n",  // Preserve newlines
5261                "ccccc\n", //
5262                "ddd\n",   //
5263                "eeee\n",  //
5264                "jj"       //
5265            )
5266        );
5267        assert_eq!(
5268            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5269            [Some(1), Some(2), Some(3), Some(4), Some(3)]
5270        );
5271        assert_eq!(
5272            snapshot.buffer_rows(MultiBufferRow(2)).collect::<Vec<_>>(),
5273            [Some(3), Some(4), Some(3)]
5274        );
5275        assert_eq!(
5276            snapshot.buffer_rows(MultiBufferRow(4)).collect::<Vec<_>>(),
5277            [Some(3)]
5278        );
5279        assert_eq!(
5280            snapshot.buffer_rows(MultiBufferRow(5)).collect::<Vec<_>>(),
5281            []
5282        );
5283
5284        assert_eq!(
5285            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
5286            &[
5287                (MultiBufferRow(0), "bbbb\nccccc".to_string(), true),
5288                (MultiBufferRow(2), "ddd\neeee".to_string(), false),
5289                (MultiBufferRow(4), "jj".to_string(), true),
5290            ]
5291        );
5292        assert_eq!(
5293            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
5294            &[(MultiBufferRow(0), "bbbb\nccccc".to_string(), true)]
5295        );
5296        assert_eq!(
5297            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
5298            &[]
5299        );
5300        assert_eq!(
5301            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
5302            &[]
5303        );
5304        assert_eq!(
5305            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
5306            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5307        );
5308        assert_eq!(
5309            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
5310            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5311        );
5312        assert_eq!(
5313            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
5314            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
5315        );
5316        assert_eq!(
5317            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
5318            &[(MultiBufferRow(4), "jj".to_string(), true)]
5319        );
5320        assert_eq!(
5321            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
5322            &[]
5323        );
5324
5325        buffer_1.update(cx, |buffer, cx| {
5326            let text = "\n";
5327            buffer.edit(
5328                [
5329                    (Point::new(0, 0)..Point::new(0, 0), text),
5330                    (Point::new(2, 1)..Point::new(2, 3), text),
5331                ],
5332                None,
5333                cx,
5334            );
5335        });
5336
5337        let snapshot = multibuffer.read(cx).snapshot(cx);
5338        assert_eq!(
5339            snapshot.text(),
5340            concat!(
5341                "bbbb\n", // Preserve newlines
5342                "c\n",    //
5343                "cc\n",   //
5344                "ddd\n",  //
5345                "eeee\n", //
5346                "jj"      //
5347            )
5348        );
5349
5350        assert_eq!(
5351            subscription.consume().into_inner(),
5352            [Edit {
5353                old: 6..8,
5354                new: 6..7
5355            }]
5356        );
5357
5358        let snapshot = multibuffer.read(cx).snapshot(cx);
5359        assert_eq!(
5360            snapshot.clip_point(Point::new(0, 5), Bias::Left),
5361            Point::new(0, 4)
5362        );
5363        assert_eq!(
5364            snapshot.clip_point(Point::new(0, 5), Bias::Right),
5365            Point::new(0, 4)
5366        );
5367        assert_eq!(
5368            snapshot.clip_point(Point::new(5, 1), Bias::Right),
5369            Point::new(5, 1)
5370        );
5371        assert_eq!(
5372            snapshot.clip_point(Point::new(5, 2), Bias::Right),
5373            Point::new(5, 2)
5374        );
5375        assert_eq!(
5376            snapshot.clip_point(Point::new(5, 3), Bias::Right),
5377            Point::new(5, 2)
5378        );
5379
5380        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
5381            let (buffer_2_excerpt_id, _) =
5382                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
5383            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
5384            multibuffer.snapshot(cx)
5385        });
5386
5387        assert_eq!(
5388            snapshot.text(),
5389            concat!(
5390                "bbbb\n", // Preserve newlines
5391                "c\n",    //
5392                "cc\n",   //
5393                "ddd\n",  //
5394                "eeee",   //
5395            )
5396        );
5397
5398        fn boundaries_in_range(
5399            range: Range<Point>,
5400            snapshot: &MultiBufferSnapshot,
5401        ) -> Vec<(MultiBufferRow, String, bool)> {
5402            snapshot
5403                .excerpt_boundaries_in_range(range)
5404                .filter_map(|boundary| {
5405                    let starts_new_buffer = boundary.starts_new_buffer();
5406                    boundary.next.map(|next| {
5407                        (
5408                            boundary.row,
5409                            next.buffer
5410                                .text_for_range(next.range.context)
5411                                .collect::<String>(),
5412                            starts_new_buffer,
5413                        )
5414                    })
5415                })
5416                .collect::<Vec<_>>()
5417        }
5418    }
5419
5420    #[gpui::test]
5421    fn test_excerpt_events(cx: &mut AppContext) {
5422        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'a'), cx));
5423        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'm'), cx));
5424
5425        let leader_multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5426        let follower_multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5427        let follower_edit_event_count = Arc::new(RwLock::new(0));
5428
5429        follower_multibuffer.update(cx, |_, cx| {
5430            let follower_edit_event_count = follower_edit_event_count.clone();
5431            cx.subscribe(
5432                &leader_multibuffer,
5433                move |follower, _, event, cx| match event.clone() {
5434                    Event::ExcerptsAdded {
5435                        buffer,
5436                        predecessor,
5437                        excerpts,
5438                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
5439                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
5440                    Event::Edited { .. } => {
5441                        *follower_edit_event_count.write() += 1;
5442                    }
5443                    _ => {}
5444                },
5445            )
5446            .detach();
5447        });
5448
5449        leader_multibuffer.update(cx, |leader, cx| {
5450            leader.push_excerpts(
5451                buffer_1.clone(),
5452                [
5453                    ExcerptRange {
5454                        context: 0..8,
5455                        primary: None,
5456                    },
5457                    ExcerptRange {
5458                        context: 12..16,
5459                        primary: None,
5460                    },
5461                ],
5462                cx,
5463            );
5464            leader.insert_excerpts_after(
5465                leader.excerpt_ids()[0],
5466                buffer_2.clone(),
5467                [
5468                    ExcerptRange {
5469                        context: 0..5,
5470                        primary: None,
5471                    },
5472                    ExcerptRange {
5473                        context: 10..15,
5474                        primary: None,
5475                    },
5476                ],
5477                cx,
5478            )
5479        });
5480        assert_eq!(
5481            leader_multibuffer.read(cx).snapshot(cx).text(),
5482            follower_multibuffer.read(cx).snapshot(cx).text(),
5483        );
5484        assert_eq!(*follower_edit_event_count.read(), 2);
5485
5486        leader_multibuffer.update(cx, |leader, cx| {
5487            let excerpt_ids = leader.excerpt_ids();
5488            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
5489        });
5490        assert_eq!(
5491            leader_multibuffer.read(cx).snapshot(cx).text(),
5492            follower_multibuffer.read(cx).snapshot(cx).text(),
5493        );
5494        assert_eq!(*follower_edit_event_count.read(), 3);
5495
5496        // Removing an empty set of excerpts is a noop.
5497        leader_multibuffer.update(cx, |leader, cx| {
5498            leader.remove_excerpts([], cx);
5499        });
5500        assert_eq!(
5501            leader_multibuffer.read(cx).snapshot(cx).text(),
5502            follower_multibuffer.read(cx).snapshot(cx).text(),
5503        );
5504        assert_eq!(*follower_edit_event_count.read(), 3);
5505
5506        // Adding an empty set of excerpts is a noop.
5507        leader_multibuffer.update(cx, |leader, cx| {
5508            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
5509        });
5510        assert_eq!(
5511            leader_multibuffer.read(cx).snapshot(cx).text(),
5512            follower_multibuffer.read(cx).snapshot(cx).text(),
5513        );
5514        assert_eq!(*follower_edit_event_count.read(), 3);
5515
5516        leader_multibuffer.update(cx, |leader, cx| {
5517            leader.clear(cx);
5518        });
5519        assert_eq!(
5520            leader_multibuffer.read(cx).snapshot(cx).text(),
5521            follower_multibuffer.read(cx).snapshot(cx).text(),
5522        );
5523        assert_eq!(*follower_edit_event_count.read(), 4);
5524    }
5525
5526    #[gpui::test]
5527    fn test_expand_excerpts(cx: &mut AppContext) {
5528        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5529        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5530
5531        multibuffer.update(cx, |multibuffer, cx| {
5532            multibuffer.push_excerpts_with_context_lines(
5533                buffer.clone(),
5534                vec![
5535                    // Note that in this test, this first excerpt
5536                    // does not contain a new line
5537                    Point::new(3, 2)..Point::new(3, 3),
5538                    Point::new(7, 1)..Point::new(7, 3),
5539                    Point::new(15, 0)..Point::new(15, 0),
5540                ],
5541                1,
5542                cx,
5543            )
5544        });
5545
5546        let snapshot = multibuffer.read(cx).snapshot(cx);
5547
5548        assert_eq!(
5549            snapshot.text(),
5550            concat!(
5551                "ccc\n", //
5552                "ddd\n", //
5553                "eee",   //
5554                "\n",    // End of excerpt
5555                "ggg\n", //
5556                "hhh\n", //
5557                "iii",   //
5558                "\n",    // End of excerpt
5559                "ooo\n", //
5560                "ppp\n", //
5561                "qqq",   // End of excerpt
5562            )
5563        );
5564        drop(snapshot);
5565
5566        multibuffer.update(cx, |multibuffer, cx| {
5567            multibuffer.expand_excerpts(
5568                multibuffer.excerpt_ids(),
5569                1,
5570                ExpandExcerptDirection::UpAndDown,
5571                cx,
5572            )
5573        });
5574
5575        let snapshot = multibuffer.read(cx).snapshot(cx);
5576
5577        // Expanding context lines causes the line containing 'fff' to appear in two different excerpts.
5578        // We don't attempt to merge them, because removing the excerpt could create inconsistency with other layers
5579        // that are tracking excerpt ids.
5580        assert_eq!(
5581            snapshot.text(),
5582            concat!(
5583                "bbb\n", //
5584                "ccc\n", //
5585                "ddd\n", //
5586                "eee\n", //
5587                "fff\n", // End of excerpt
5588                "fff\n", //
5589                "ggg\n", //
5590                "hhh\n", //
5591                "iii\n", //
5592                "jjj\n", // End of excerpt
5593                "nnn\n", //
5594                "ooo\n", //
5595                "ppp\n", //
5596                "qqq\n", //
5597                "rrr",   // End of excerpt
5598            )
5599        );
5600    }
5601
5602    #[gpui::test]
5603    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
5604        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5605        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5606        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
5607            multibuffer.push_excerpts_with_context_lines(
5608                buffer.clone(),
5609                vec![
5610                    // Note that in this test, this first excerpt
5611                    // does contain a new line
5612                    Point::new(3, 2)..Point::new(4, 2),
5613                    Point::new(7, 1)..Point::new(7, 3),
5614                    Point::new(15, 0)..Point::new(15, 0),
5615                ],
5616                2,
5617                cx,
5618            )
5619        });
5620
5621        let snapshot = multibuffer.read(cx).snapshot(cx);
5622        assert_eq!(
5623            snapshot.text(),
5624            concat!(
5625                "bbb\n", // Preserve newlines
5626                "ccc\n", //
5627                "ddd\n", //
5628                "eee\n", //
5629                "fff\n", //
5630                "ggg\n", //
5631                "hhh\n", //
5632                "iii\n", //
5633                "jjj\n", //
5634                "nnn\n", //
5635                "ooo\n", //
5636                "ppp\n", //
5637                "qqq\n", //
5638                "rrr",   //
5639            )
5640        );
5641
5642        assert_eq!(
5643            anchor_ranges
5644                .iter()
5645                .map(|range| range.to_point(&snapshot))
5646                .collect::<Vec<_>>(),
5647            vec![
5648                Point::new(2, 2)..Point::new(3, 2),
5649                Point::new(6, 1)..Point::new(6, 3),
5650                Point::new(11, 0)..Point::new(11, 0)
5651            ]
5652        );
5653    }
5654
5655    #[gpui::test(iterations = 100)]
5656    async fn test_push_multiple_excerpts_with_context_lines(cx: &mut TestAppContext) {
5657        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5658        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(15, 4, 'a'), cx));
5659        let snapshot_1 = buffer_1.update(cx, |buffer, _| buffer.snapshot());
5660        let snapshot_2 = buffer_2.update(cx, |buffer, _| buffer.snapshot());
5661        let ranges_1 = vec![
5662            snapshot_1.anchor_before(Point::new(3, 2))..snapshot_1.anchor_before(Point::new(4, 2)),
5663            snapshot_1.anchor_before(Point::new(7, 1))..snapshot_1.anchor_before(Point::new(7, 3)),
5664            snapshot_1.anchor_before(Point::new(15, 0))
5665                ..snapshot_1.anchor_before(Point::new(15, 0)),
5666        ];
5667        let ranges_2 = vec![
5668            snapshot_2.anchor_before(Point::new(2, 1))..snapshot_2.anchor_before(Point::new(3, 1)),
5669            snapshot_2.anchor_before(Point::new(10, 0))
5670                ..snapshot_2.anchor_before(Point::new(10, 2)),
5671        ];
5672
5673        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5674        let anchor_ranges = multibuffer
5675            .update(cx, |multibuffer, cx| {
5676                multibuffer.push_multiple_excerpts_with_context_lines(
5677                    vec![(buffer_1.clone(), ranges_1), (buffer_2.clone(), ranges_2)],
5678                    2,
5679                    cx,
5680                )
5681            })
5682            .await;
5683
5684        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
5685        assert_eq!(
5686            snapshot.text(),
5687            concat!(
5688                "bbb\n", // buffer_1
5689                "ccc\n", //
5690                "ddd\n", // <-- excerpt 1
5691                "eee\n", // <-- excerpt 1
5692                "fff\n", //
5693                "ggg\n", //
5694                "hhh\n", // <-- excerpt 2
5695                "iii\n", //
5696                "jjj\n", //
5697                //
5698                "nnn\n", //
5699                "ooo\n", //
5700                "ppp\n", // <-- excerpt 3
5701                "qqq\n", //
5702                "rrr\n", //
5703                //
5704                "aaaa\n", // buffer 2
5705                "bbbb\n", //
5706                "cccc\n", // <-- excerpt 4
5707                "dddd\n", // <-- excerpt 4
5708                "eeee\n", //
5709                "ffff\n", //
5710                //
5711                "iiii\n", //
5712                "jjjj\n", //
5713                "kkkk\n", // <-- excerpt 5
5714                "llll\n", //
5715                "mmmm",   //
5716            )
5717        );
5718
5719        assert_eq!(
5720            anchor_ranges
5721                .iter()
5722                .map(|range| range.to_point(&snapshot))
5723                .collect::<Vec<_>>(),
5724            vec![
5725                Point::new(2, 2)..Point::new(3, 2),
5726                Point::new(6, 1)..Point::new(6, 3),
5727                Point::new(11, 0)..Point::new(11, 0),
5728                Point::new(16, 1)..Point::new(17, 1),
5729                Point::new(22, 0)..Point::new(22, 2)
5730            ]
5731        );
5732    }
5733
5734    #[gpui::test]
5735    fn test_empty_multibuffer(cx: &mut AppContext) {
5736        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5737
5738        let snapshot = multibuffer.read(cx).snapshot(cx);
5739        assert_eq!(snapshot.text(), "");
5740        assert_eq!(
5741            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5742            &[Some(0)]
5743        );
5744        assert_eq!(
5745            snapshot.buffer_rows(MultiBufferRow(1)).collect::<Vec<_>>(),
5746            &[]
5747        );
5748    }
5749
5750    #[gpui::test]
5751    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
5752        let buffer = cx.new_model(|cx| Buffer::local("abcd", cx));
5753        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
5754        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5755        buffer.update(cx, |buffer, cx| {
5756            buffer.edit([(0..0, "X")], None, cx);
5757            buffer.edit([(5..5, "Y")], None, cx);
5758        });
5759        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5760
5761        assert_eq!(old_snapshot.text(), "abcd");
5762        assert_eq!(new_snapshot.text(), "XabcdY");
5763
5764        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5765        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5766        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
5767        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
5768    }
5769
5770    #[gpui::test]
5771    fn test_multibuffer_anchors(cx: &mut AppContext) {
5772        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5773        let buffer_2 = cx.new_model(|cx| Buffer::local("efghi", cx));
5774        let multibuffer = cx.new_model(|cx| {
5775            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
5776            multibuffer.push_excerpts(
5777                buffer_1.clone(),
5778                [ExcerptRange {
5779                    context: 0..4,
5780                    primary: None,
5781                }],
5782                cx,
5783            );
5784            multibuffer.push_excerpts(
5785                buffer_2.clone(),
5786                [ExcerptRange {
5787                    context: 0..5,
5788                    primary: None,
5789                }],
5790                cx,
5791            );
5792            multibuffer
5793        });
5794        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5795
5796        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
5797        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
5798        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5799        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5800        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5801        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5802
5803        buffer_1.update(cx, |buffer, cx| {
5804            buffer.edit([(0..0, "W")], None, cx);
5805            buffer.edit([(5..5, "X")], None, cx);
5806        });
5807        buffer_2.update(cx, |buffer, cx| {
5808            buffer.edit([(0..0, "Y")], None, cx);
5809            buffer.edit([(6..6, "Z")], None, cx);
5810        });
5811        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5812
5813        assert_eq!(old_snapshot.text(), "abcd\nefghi");
5814        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
5815
5816        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5817        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5818        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
5819        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
5820        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
5821        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
5822        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
5823        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
5824        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
5825        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
5826    }
5827
5828    #[gpui::test]
5829    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
5830        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5831        let buffer_2 = cx.new_model(|cx| Buffer::local("ABCDEFGHIJKLMNOP", cx));
5832        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5833
5834        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
5835        // Add an excerpt from buffer 1 that spans this new insertion.
5836        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
5837        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
5838            multibuffer
5839                .push_excerpts(
5840                    buffer_1.clone(),
5841                    [ExcerptRange {
5842                        context: 0..7,
5843                        primary: None,
5844                    }],
5845                    cx,
5846                )
5847                .pop()
5848                .unwrap()
5849        });
5850
5851        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
5852        assert_eq!(snapshot_1.text(), "abcd123");
5853
5854        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
5855        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
5856            multibuffer.remove_excerpts([excerpt_id_1], cx);
5857            let mut ids = multibuffer
5858                .push_excerpts(
5859                    buffer_2.clone(),
5860                    [
5861                        ExcerptRange {
5862                            context: 0..4,
5863                            primary: None,
5864                        },
5865                        ExcerptRange {
5866                            context: 6..10,
5867                            primary: None,
5868                        },
5869                        ExcerptRange {
5870                            context: 12..16,
5871                            primary: None,
5872                        },
5873                    ],
5874                    cx,
5875                )
5876                .into_iter();
5877            (ids.next().unwrap(), ids.next().unwrap())
5878        });
5879        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
5880        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
5881
5882        // The old excerpt id doesn't get reused.
5883        assert_ne!(excerpt_id_2, excerpt_id_1);
5884
5885        // Resolve some anchors from the previous snapshot in the new snapshot.
5886        // The current excerpts are from a different buffer, so we don't attempt to
5887        // resolve the old text anchor in the new buffer.
5888        assert_eq!(
5889            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
5890            0
5891        );
5892        assert_eq!(
5893            snapshot_2.summaries_for_anchors::<usize, _>(&[
5894                snapshot_1.anchor_before(2),
5895                snapshot_1.anchor_after(3)
5896            ]),
5897            vec![0, 0]
5898        );
5899
5900        // Refresh anchors from the old snapshot. The return value indicates that both
5901        // anchors lost their original excerpt.
5902        let refresh =
5903            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
5904        assert_eq!(
5905            refresh,
5906            &[
5907                (0, snapshot_2.anchor_before(0), false),
5908                (1, snapshot_2.anchor_after(0), false),
5909            ]
5910        );
5911
5912        // Replace the middle excerpt with a smaller excerpt in buffer 2,
5913        // that intersects the old excerpt.
5914        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
5915            multibuffer.remove_excerpts([excerpt_id_3], cx);
5916            multibuffer
5917                .insert_excerpts_after(
5918                    excerpt_id_2,
5919                    buffer_2.clone(),
5920                    [ExcerptRange {
5921                        context: 5..8,
5922                        primary: None,
5923                    }],
5924                    cx,
5925                )
5926                .pop()
5927                .unwrap()
5928        });
5929
5930        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
5931        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
5932        assert_ne!(excerpt_id_5, excerpt_id_3);
5933
5934        // Resolve some anchors from the previous snapshot in the new snapshot.
5935        // The third anchor can't be resolved, since its excerpt has been removed,
5936        // so it resolves to the same position as its predecessor.
5937        let anchors = [
5938            snapshot_2.anchor_before(0),
5939            snapshot_2.anchor_after(2),
5940            snapshot_2.anchor_after(6),
5941            snapshot_2.anchor_after(14),
5942        ];
5943        assert_eq!(
5944            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
5945            &[0, 2, 9, 13]
5946        );
5947
5948        let new_anchors = snapshot_3.refresh_anchors(&anchors);
5949        assert_eq!(
5950            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
5951            &[(0, true), (1, true), (2, true), (3, true)]
5952        );
5953        assert_eq!(
5954            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
5955            &[0, 2, 7, 13]
5956        );
5957    }
5958
5959    #[gpui::test(iterations = 100)]
5960    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
5961        let operations = env::var("OPERATIONS")
5962            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
5963            .unwrap_or(10);
5964
5965        let mut buffers: Vec<Model<Buffer>> = Vec::new();
5966        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
5967        let mut excerpt_ids = Vec::<ExcerptId>::new();
5968        let mut expected_excerpts = Vec::<(Model<Buffer>, Range<text::Anchor>)>::new();
5969        let mut anchors = Vec::new();
5970        let mut old_versions = Vec::new();
5971
5972        for _ in 0..operations {
5973            match rng.gen_range(0..100) {
5974                0..=14 if !buffers.is_empty() => {
5975                    let buffer = buffers.choose(&mut rng).unwrap();
5976                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
5977                }
5978                15..=19 if !expected_excerpts.is_empty() => {
5979                    multibuffer.update(cx, |multibuffer, cx| {
5980                        let ids = multibuffer.excerpt_ids();
5981                        let mut excerpts = HashSet::default();
5982                        for _ in 0..rng.gen_range(0..ids.len()) {
5983                            excerpts.extend(ids.choose(&mut rng).copied());
5984                        }
5985
5986                        let line_count = rng.gen_range(0..5);
5987
5988                        let excerpt_ixs = excerpts
5989                            .iter()
5990                            .map(|id| excerpt_ids.iter().position(|i| i == id).unwrap())
5991                            .collect::<Vec<_>>();
5992                        log::info!("Expanding excerpts {excerpt_ixs:?} by {line_count} lines");
5993                        multibuffer.expand_excerpts(
5994                            excerpts.iter().cloned(),
5995                            line_count,
5996                            ExpandExcerptDirection::UpAndDown,
5997                            cx,
5998                        );
5999
6000                        if line_count > 0 {
6001                            for id in excerpts {
6002                                let excerpt_ix = excerpt_ids.iter().position(|&i| i == id).unwrap();
6003                                let (buffer, range) = &mut expected_excerpts[excerpt_ix];
6004                                let snapshot = buffer.read(cx).snapshot();
6005                                let mut point_range = range.to_point(&snapshot);
6006                                point_range.start =
6007                                    Point::new(point_range.start.row.saturating_sub(line_count), 0);
6008                                point_range.end = snapshot.clip_point(
6009                                    Point::new(point_range.end.row + line_count, 0),
6010                                    Bias::Left,
6011                                );
6012                                point_range.end.column = snapshot.line_len(point_range.end.row);
6013                                *range = snapshot.anchor_before(point_range.start)
6014                                    ..snapshot.anchor_after(point_range.end);
6015                            }
6016                        }
6017                    });
6018                }
6019                20..=29 if !expected_excerpts.is_empty() => {
6020                    let mut ids_to_remove = vec![];
6021                    for _ in 0..rng.gen_range(1..=3) {
6022                        if expected_excerpts.is_empty() {
6023                            break;
6024                        }
6025
6026                        let ix = rng.gen_range(0..expected_excerpts.len());
6027                        ids_to_remove.push(excerpt_ids.remove(ix));
6028                        let (buffer, range) = expected_excerpts.remove(ix);
6029                        let buffer = buffer.read(cx);
6030                        log::info!(
6031                            "Removing excerpt {}: {:?}",
6032                            ix,
6033                            buffer
6034                                .text_for_range(range.to_offset(buffer))
6035                                .collect::<String>(),
6036                        );
6037                    }
6038                    let snapshot = multibuffer.read(cx).read(cx);
6039                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
6040                    drop(snapshot);
6041                    multibuffer.update(cx, |multibuffer, cx| {
6042                        multibuffer.remove_excerpts(ids_to_remove, cx)
6043                    });
6044                }
6045                30..=39 if !expected_excerpts.is_empty() => {
6046                    let multibuffer = multibuffer.read(cx).read(cx);
6047                    let offset =
6048                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
6049                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
6050                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
6051                    anchors.push(multibuffer.anchor_at(offset, bias));
6052                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
6053                }
6054                40..=44 if !anchors.is_empty() => {
6055                    let multibuffer = multibuffer.read(cx).read(cx);
6056                    let prev_len = anchors.len();
6057                    anchors = multibuffer
6058                        .refresh_anchors(&anchors)
6059                        .into_iter()
6060                        .map(|a| a.1)
6061                        .collect();
6062
6063                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
6064                    // overshoot its boundaries.
6065                    assert_eq!(anchors.len(), prev_len);
6066                    for anchor in &anchors {
6067                        if anchor.excerpt_id == ExcerptId::min()
6068                            || anchor.excerpt_id == ExcerptId::max()
6069                        {
6070                            continue;
6071                        }
6072
6073                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
6074                        assert_eq!(excerpt.id, anchor.excerpt_id);
6075                        assert!(excerpt.contains(anchor));
6076                    }
6077                }
6078                _ => {
6079                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
6080                        let base_text = util::RandomCharIter::new(&mut rng)
6081                            .take(25)
6082                            .collect::<String>();
6083
6084                        buffers.push(cx.new_model(|cx| Buffer::local(base_text, cx)));
6085                        buffers.last().unwrap()
6086                    } else {
6087                        buffers.choose(&mut rng).unwrap()
6088                    };
6089
6090                    let buffer = buffer_handle.read(cx);
6091                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
6092                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
6093                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
6094                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
6095                    let prev_excerpt_id = excerpt_ids
6096                        .get(prev_excerpt_ix)
6097                        .cloned()
6098                        .unwrap_or_else(ExcerptId::max);
6099                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
6100
6101                    log::info!(
6102                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
6103                        excerpt_ix,
6104                        expected_excerpts.len(),
6105                        buffer_handle.read(cx).remote_id(),
6106                        buffer.text(),
6107                        start_ix..end_ix,
6108                        &buffer.text()[start_ix..end_ix]
6109                    );
6110
6111                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
6112                        multibuffer
6113                            .insert_excerpts_after(
6114                                prev_excerpt_id,
6115                                buffer_handle.clone(),
6116                                [ExcerptRange {
6117                                    context: start_ix..end_ix,
6118                                    primary: None,
6119                                }],
6120                                cx,
6121                            )
6122                            .pop()
6123                            .unwrap()
6124                    });
6125
6126                    excerpt_ids.insert(excerpt_ix, excerpt_id);
6127                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
6128                }
6129            }
6130
6131            if rng.gen_bool(0.3) {
6132                multibuffer.update(cx, |multibuffer, cx| {
6133                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
6134                })
6135            }
6136
6137            let snapshot = multibuffer.read(cx).snapshot(cx);
6138
6139            let mut excerpt_starts = Vec::new();
6140            let mut expected_text = String::new();
6141            let mut expected_buffer_rows = Vec::new();
6142            for (buffer, range) in &expected_excerpts {
6143                let buffer = buffer.read(cx);
6144                let buffer_range = range.to_offset(buffer);
6145
6146                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
6147                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
6148                expected_text.push('\n');
6149
6150                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
6151                    ..=buffer.offset_to_point(buffer_range.end).row;
6152                for row in buffer_row_range {
6153                    expected_buffer_rows.push(Some(row));
6154                }
6155            }
6156            // Remove final trailing newline.
6157            if !expected_excerpts.is_empty() {
6158                expected_text.pop();
6159            }
6160
6161            // Always report one buffer row
6162            if expected_buffer_rows.is_empty() {
6163                expected_buffer_rows.push(Some(0));
6164            }
6165
6166            assert_eq!(snapshot.text(), expected_text);
6167            log::info!("MultiBuffer text: {:?}", expected_text);
6168
6169            assert_eq!(
6170                snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
6171                expected_buffer_rows,
6172            );
6173
6174            for _ in 0..5 {
6175                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
6176                assert_eq!(
6177                    snapshot
6178                        .buffer_rows(MultiBufferRow(start_row as u32))
6179                        .collect::<Vec<_>>(),
6180                    &expected_buffer_rows[start_row..],
6181                    "buffer_rows({})",
6182                    start_row
6183                );
6184            }
6185
6186            assert_eq!(
6187                snapshot.max_buffer_row().0,
6188                expected_buffer_rows.into_iter().flatten().max().unwrap()
6189            );
6190
6191            let mut excerpt_starts = excerpt_starts.into_iter();
6192            for (buffer, range) in &expected_excerpts {
6193                let buffer = buffer.read(cx);
6194                let buffer_id = buffer.remote_id();
6195                let buffer_range = range.to_offset(buffer);
6196                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
6197                let buffer_start_point_utf16 =
6198                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
6199
6200                let excerpt_start = excerpt_starts.next().unwrap();
6201                let mut offset = excerpt_start.len;
6202                let mut buffer_offset = buffer_range.start;
6203                let mut point = excerpt_start.lines;
6204                let mut buffer_point = buffer_start_point;
6205                let mut point_utf16 = excerpt_start.lines_utf16();
6206                let mut buffer_point_utf16 = buffer_start_point_utf16;
6207                for ch in buffer
6208                    .snapshot()
6209                    .chunks(buffer_range.clone(), false)
6210                    .flat_map(|c| c.text.chars())
6211                {
6212                    for _ in 0..ch.len_utf8() {
6213                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
6214                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
6215                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
6216                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
6217                        assert_eq!(
6218                            left_offset,
6219                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
6220                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
6221                            offset,
6222                            buffer_id,
6223                            buffer_offset,
6224                        );
6225                        assert_eq!(
6226                            right_offset,
6227                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
6228                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
6229                            offset,
6230                            buffer_id,
6231                            buffer_offset,
6232                        );
6233
6234                        let left_point = snapshot.clip_point(point, Bias::Left);
6235                        let right_point = snapshot.clip_point(point, Bias::Right);
6236                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
6237                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
6238                        assert_eq!(
6239                            left_point,
6240                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
6241                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
6242                            point,
6243                            buffer_id,
6244                            buffer_point,
6245                        );
6246                        assert_eq!(
6247                            right_point,
6248                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
6249                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
6250                            point,
6251                            buffer_id,
6252                            buffer_point,
6253                        );
6254
6255                        assert_eq!(
6256                            snapshot.point_to_offset(left_point),
6257                            left_offset,
6258                            "point_to_offset({:?})",
6259                            left_point,
6260                        );
6261                        assert_eq!(
6262                            snapshot.offset_to_point(left_offset),
6263                            left_point,
6264                            "offset_to_point({:?})",
6265                            left_offset,
6266                        );
6267
6268                        offset += 1;
6269                        buffer_offset += 1;
6270                        if ch == '\n' {
6271                            point += Point::new(1, 0);
6272                            buffer_point += Point::new(1, 0);
6273                        } else {
6274                            point += Point::new(0, 1);
6275                            buffer_point += Point::new(0, 1);
6276                        }
6277                    }
6278
6279                    for _ in 0..ch.len_utf16() {
6280                        let left_point_utf16 =
6281                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
6282                        let right_point_utf16 =
6283                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
6284                        let buffer_left_point_utf16 =
6285                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
6286                        let buffer_right_point_utf16 =
6287                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
6288                        assert_eq!(
6289                            left_point_utf16,
6290                            excerpt_start.lines_utf16()
6291                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
6292                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
6293                            point_utf16,
6294                            buffer_id,
6295                            buffer_point_utf16,
6296                        );
6297                        assert_eq!(
6298                            right_point_utf16,
6299                            excerpt_start.lines_utf16()
6300                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
6301                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
6302                            point_utf16,
6303                            buffer_id,
6304                            buffer_point_utf16,
6305                        );
6306
6307                        if ch == '\n' {
6308                            point_utf16 += PointUtf16::new(1, 0);
6309                            buffer_point_utf16 += PointUtf16::new(1, 0);
6310                        } else {
6311                            point_utf16 += PointUtf16::new(0, 1);
6312                            buffer_point_utf16 += PointUtf16::new(0, 1);
6313                        }
6314                    }
6315                }
6316            }
6317
6318            for (row, line) in expected_text.split('\n').enumerate() {
6319                assert_eq!(
6320                    snapshot.line_len(MultiBufferRow(row as u32)),
6321                    line.len() as u32,
6322                    "line_len({}).",
6323                    row
6324                );
6325            }
6326
6327            let text_rope = Rope::from(expected_text.as_str());
6328            for _ in 0..10 {
6329                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
6330                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
6331
6332                let text_for_range = snapshot
6333                    .text_for_range(start_ix..end_ix)
6334                    .collect::<String>();
6335                assert_eq!(
6336                    text_for_range,
6337                    &expected_text[start_ix..end_ix],
6338                    "incorrect text for range {:?}",
6339                    start_ix..end_ix
6340                );
6341
6342                let excerpted_buffer_ranges = multibuffer
6343                    .read(cx)
6344                    .range_to_buffer_ranges(start_ix..end_ix, cx);
6345                let excerpted_buffers_text = excerpted_buffer_ranges
6346                    .iter()
6347                    .map(|(buffer, buffer_range, _)| {
6348                        buffer
6349                            .read(cx)
6350                            .text_for_range(buffer_range.clone())
6351                            .collect::<String>()
6352                    })
6353                    .collect::<Vec<_>>()
6354                    .join("\n");
6355                assert_eq!(excerpted_buffers_text, text_for_range);
6356                if !expected_excerpts.is_empty() {
6357                    assert!(!excerpted_buffer_ranges.is_empty());
6358                }
6359
6360                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
6361                assert_eq!(
6362                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
6363                    expected_summary,
6364                    "incorrect summary for range {:?}",
6365                    start_ix..end_ix
6366                );
6367            }
6368
6369            // Anchor resolution
6370            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
6371            assert_eq!(anchors.len(), summaries.len());
6372            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
6373                assert!(resolved_offset <= snapshot.len());
6374                assert_eq!(
6375                    snapshot.summary_for_anchor::<usize>(anchor),
6376                    resolved_offset
6377                );
6378            }
6379
6380            for _ in 0..10 {
6381                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
6382                assert_eq!(
6383                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
6384                    expected_text[..end_ix].chars().rev().collect::<String>(),
6385                );
6386            }
6387
6388            for _ in 0..10 {
6389                let end_ix = rng.gen_range(0..=text_rope.len());
6390                let start_ix = rng.gen_range(0..=end_ix);
6391                assert_eq!(
6392                    snapshot
6393                        .bytes_in_range(start_ix..end_ix)
6394                        .flatten()
6395                        .copied()
6396                        .collect::<Vec<_>>(),
6397                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
6398                    "bytes_in_range({:?})",
6399                    start_ix..end_ix,
6400                );
6401            }
6402        }
6403
6404        let snapshot = multibuffer.read(cx).snapshot(cx);
6405        for (old_snapshot, subscription) in old_versions {
6406            let edits = subscription.consume().into_inner();
6407
6408            log::info!(
6409                "applying subscription edits to old text: {:?}: {:?}",
6410                old_snapshot.text(),
6411                edits,
6412            );
6413
6414            let mut text = old_snapshot.text();
6415            for edit in edits {
6416                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
6417                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
6418            }
6419            assert_eq!(text.to_string(), snapshot.text());
6420        }
6421    }
6422
6423    #[gpui::test]
6424    fn test_history(cx: &mut AppContext) {
6425        let test_settings = SettingsStore::test(cx);
6426        cx.set_global(test_settings);
6427
6428        let buffer_1 = cx.new_model(|cx| Buffer::local("1234", cx));
6429        let buffer_2 = cx.new_model(|cx| Buffer::local("5678", cx));
6430        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6431        let group_interval = multibuffer.read(cx).history.group_interval;
6432        multibuffer.update(cx, |multibuffer, cx| {
6433            multibuffer.push_excerpts(
6434                buffer_1.clone(),
6435                [ExcerptRange {
6436                    context: 0..buffer_1.read(cx).len(),
6437                    primary: None,
6438                }],
6439                cx,
6440            );
6441            multibuffer.push_excerpts(
6442                buffer_2.clone(),
6443                [ExcerptRange {
6444                    context: 0..buffer_2.read(cx).len(),
6445                    primary: None,
6446                }],
6447                cx,
6448            );
6449        });
6450
6451        let mut now = Instant::now();
6452
6453        multibuffer.update(cx, |multibuffer, cx| {
6454            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
6455            multibuffer.edit(
6456                [
6457                    (Point::new(0, 0)..Point::new(0, 0), "A"),
6458                    (Point::new(1, 0)..Point::new(1, 0), "A"),
6459                ],
6460                None,
6461                cx,
6462            );
6463            multibuffer.edit(
6464                [
6465                    (Point::new(0, 1)..Point::new(0, 1), "B"),
6466                    (Point::new(1, 1)..Point::new(1, 1), "B"),
6467                ],
6468                None,
6469                cx,
6470            );
6471            multibuffer.end_transaction_at(now, cx);
6472            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6473
6474            // Verify edited ranges for transaction 1
6475            assert_eq!(
6476                multibuffer.edited_ranges_for_transaction(transaction_1, cx),
6477                &[
6478                    Point::new(0, 0)..Point::new(0, 2),
6479                    Point::new(1, 0)..Point::new(1, 2)
6480                ]
6481            );
6482
6483            // Edit buffer 1 through the multibuffer
6484            now += 2 * group_interval;
6485            multibuffer.start_transaction_at(now, cx);
6486            multibuffer.edit([(2..2, "C")], None, cx);
6487            multibuffer.end_transaction_at(now, cx);
6488            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
6489
6490            // Edit buffer 1 independently
6491            buffer_1.update(cx, |buffer_1, cx| {
6492                buffer_1.start_transaction_at(now);
6493                buffer_1.edit([(3..3, "D")], None, cx);
6494                buffer_1.end_transaction_at(now, cx);
6495
6496                now += 2 * group_interval;
6497                buffer_1.start_transaction_at(now);
6498                buffer_1.edit([(4..4, "E")], None, cx);
6499                buffer_1.end_transaction_at(now, cx);
6500            });
6501            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
6502
6503            // An undo in the multibuffer undoes the multibuffer transaction
6504            // and also any individual buffer edits that have occurred since
6505            // that transaction.
6506            multibuffer.undo(cx);
6507            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6508
6509            multibuffer.undo(cx);
6510            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6511
6512            multibuffer.redo(cx);
6513            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6514
6515            multibuffer.redo(cx);
6516            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
6517
6518            // Undo buffer 2 independently.
6519            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
6520            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
6521
6522            // An undo in the multibuffer undoes the components of the
6523            // the last multibuffer transaction that are not already undone.
6524            multibuffer.undo(cx);
6525            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
6526
6527            multibuffer.undo(cx);
6528            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6529
6530            multibuffer.redo(cx);
6531            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
6532
6533            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
6534            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
6535
6536            // Redo stack gets cleared after an edit.
6537            now += 2 * group_interval;
6538            multibuffer.start_transaction_at(now, cx);
6539            multibuffer.edit([(0..0, "X")], None, cx);
6540            multibuffer.end_transaction_at(now, cx);
6541            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6542            multibuffer.redo(cx);
6543            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6544            multibuffer.undo(cx);
6545            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
6546            multibuffer.undo(cx);
6547            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6548
6549            // Transactions can be grouped manually.
6550            multibuffer.redo(cx);
6551            multibuffer.redo(cx);
6552            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6553            multibuffer.group_until_transaction(transaction_1, cx);
6554            multibuffer.undo(cx);
6555            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
6556            multibuffer.redo(cx);
6557            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
6558        });
6559    }
6560
6561    #[gpui::test]
6562    fn test_excerpts_in_ranges_no_ranges(cx: &mut AppContext) {
6563        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6564        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6565        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6566        multibuffer.update(cx, |multibuffer, cx| {
6567            multibuffer.push_excerpts(
6568                buffer_1.clone(),
6569                [ExcerptRange {
6570                    context: 0..buffer_1.read(cx).len(),
6571                    primary: None,
6572                }],
6573                cx,
6574            );
6575            multibuffer.push_excerpts(
6576                buffer_2.clone(),
6577                [ExcerptRange {
6578                    context: 0..buffer_2.read(cx).len(),
6579                    primary: None,
6580                }],
6581                cx,
6582            );
6583        });
6584
6585        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
6586
6587        let mut excerpts = snapshot.excerpts_in_ranges(iter::from_fn(|| None));
6588
6589        assert!(excerpts.next().is_none());
6590    }
6591
6592    fn validate_excerpts(
6593        actual: &[(ExcerptId, BufferId, Range<Anchor>)],
6594        expected: &Vec<(ExcerptId, BufferId, Range<Anchor>)>,
6595    ) {
6596        assert_eq!(actual.len(), expected.len());
6597
6598        actual
6599            .iter()
6600            .zip(expected)
6601            .map(|(actual, expected)| {
6602                assert_eq!(actual.0, expected.0);
6603                assert_eq!(actual.1, expected.1);
6604                assert_eq!(actual.2.start, expected.2.start);
6605                assert_eq!(actual.2.end, expected.2.end);
6606            })
6607            .collect_vec();
6608    }
6609
6610    fn map_range_from_excerpt(
6611        snapshot: &MultiBufferSnapshot,
6612        excerpt_id: ExcerptId,
6613        excerpt_buffer: &BufferSnapshot,
6614        range: Range<usize>,
6615    ) -> Range<Anchor> {
6616        snapshot
6617            .anchor_in_excerpt(excerpt_id, excerpt_buffer.anchor_before(range.start))
6618            .unwrap()
6619            ..snapshot
6620                .anchor_in_excerpt(excerpt_id, excerpt_buffer.anchor_after(range.end))
6621                .unwrap()
6622    }
6623
6624    fn make_expected_excerpt_info(
6625        snapshot: &MultiBufferSnapshot,
6626        cx: &mut AppContext,
6627        excerpt_id: ExcerptId,
6628        buffer: &Model<Buffer>,
6629        range: Range<usize>,
6630    ) -> (ExcerptId, BufferId, Range<Anchor>) {
6631        (
6632            excerpt_id,
6633            buffer.read(cx).remote_id(),
6634            map_range_from_excerpt(snapshot, excerpt_id, &buffer.read(cx).snapshot(), range),
6635        )
6636    }
6637
6638    #[gpui::test]
6639    fn test_excerpts_in_ranges_range_inside_the_excerpt(cx: &mut AppContext) {
6640        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6641        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6642        let buffer_len = buffer_1.read(cx).len();
6643        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6644        let mut expected_excerpt_id = ExcerptId(0);
6645
6646        multibuffer.update(cx, |multibuffer, cx| {
6647            expected_excerpt_id = multibuffer.push_excerpts(
6648                buffer_1.clone(),
6649                [ExcerptRange {
6650                    context: 0..buffer_1.read(cx).len(),
6651                    primary: None,
6652                }],
6653                cx,
6654            )[0];
6655            multibuffer.push_excerpts(
6656                buffer_2.clone(),
6657                [ExcerptRange {
6658                    context: 0..buffer_2.read(cx).len(),
6659                    primary: None,
6660                }],
6661                cx,
6662            );
6663        });
6664
6665        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
6666
6667        let range = snapshot
6668            .anchor_in_excerpt(expected_excerpt_id, buffer_1.read(cx).anchor_before(1))
6669            .unwrap()
6670            ..snapshot
6671                .anchor_in_excerpt(
6672                    expected_excerpt_id,
6673                    buffer_1.read(cx).anchor_after(buffer_len / 2),
6674                )
6675                .unwrap();
6676
6677        let expected_excerpts = vec![make_expected_excerpt_info(
6678            &snapshot,
6679            cx,
6680            expected_excerpt_id,
6681            &buffer_1,
6682            1..(buffer_len / 2),
6683        )];
6684
6685        let excerpts = snapshot
6686            .excerpts_in_ranges(vec![range.clone()].into_iter())
6687            .map(|(excerpt_id, buffer, actual_range)| {
6688                (
6689                    excerpt_id,
6690                    buffer.remote_id(),
6691                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6692                )
6693            })
6694            .collect_vec();
6695
6696        validate_excerpts(&excerpts, &expected_excerpts);
6697    }
6698
6699    #[gpui::test]
6700    fn test_excerpts_in_ranges_range_crosses_excerpts_boundary(cx: &mut AppContext) {
6701        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6702        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6703        let buffer_len = buffer_1.read(cx).len();
6704        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6705        let mut excerpt_1_id = ExcerptId(0);
6706        let mut excerpt_2_id = ExcerptId(0);
6707
6708        multibuffer.update(cx, |multibuffer, cx| {
6709            excerpt_1_id = multibuffer.push_excerpts(
6710                buffer_1.clone(),
6711                [ExcerptRange {
6712                    context: 0..buffer_1.read(cx).len(),
6713                    primary: None,
6714                }],
6715                cx,
6716            )[0];
6717            excerpt_2_id = multibuffer.push_excerpts(
6718                buffer_2.clone(),
6719                [ExcerptRange {
6720                    context: 0..buffer_2.read(cx).len(),
6721                    primary: None,
6722                }],
6723                cx,
6724            )[0];
6725        });
6726
6727        let snapshot = multibuffer.read(cx).snapshot(cx);
6728
6729        let expected_range = snapshot
6730            .anchor_in_excerpt(
6731                excerpt_1_id,
6732                buffer_1.read(cx).anchor_before(buffer_len / 2),
6733            )
6734            .unwrap()
6735            ..snapshot
6736                .anchor_in_excerpt(excerpt_2_id, buffer_2.read(cx).anchor_after(buffer_len / 2))
6737                .unwrap();
6738
6739        let expected_excerpts = vec![
6740            make_expected_excerpt_info(
6741                &snapshot,
6742                cx,
6743                excerpt_1_id,
6744                &buffer_1,
6745                (buffer_len / 2)..buffer_len,
6746            ),
6747            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, 0..buffer_len / 2),
6748        ];
6749
6750        let excerpts = snapshot
6751            .excerpts_in_ranges(vec![expected_range.clone()].into_iter())
6752            .map(|(excerpt_id, buffer, actual_range)| {
6753                (
6754                    excerpt_id,
6755                    buffer.remote_id(),
6756                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6757                )
6758            })
6759            .collect_vec();
6760
6761        validate_excerpts(&excerpts, &expected_excerpts);
6762    }
6763
6764    #[gpui::test]
6765    fn test_excerpts_in_ranges_range_encloses_excerpt(cx: &mut AppContext) {
6766        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6767        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6768        let buffer_3 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'r'), cx));
6769        let buffer_len = buffer_1.read(cx).len();
6770        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6771        let mut excerpt_1_id = ExcerptId(0);
6772        let mut excerpt_2_id = ExcerptId(0);
6773        let mut excerpt_3_id = ExcerptId(0);
6774
6775        multibuffer.update(cx, |multibuffer, cx| {
6776            excerpt_1_id = multibuffer.push_excerpts(
6777                buffer_1.clone(),
6778                [ExcerptRange {
6779                    context: 0..buffer_1.read(cx).len(),
6780                    primary: None,
6781                }],
6782                cx,
6783            )[0];
6784            excerpt_2_id = multibuffer.push_excerpts(
6785                buffer_2.clone(),
6786                [ExcerptRange {
6787                    context: 0..buffer_2.read(cx).len(),
6788                    primary: None,
6789                }],
6790                cx,
6791            )[0];
6792            excerpt_3_id = multibuffer.push_excerpts(
6793                buffer_3.clone(),
6794                [ExcerptRange {
6795                    context: 0..buffer_3.read(cx).len(),
6796                    primary: None,
6797                }],
6798                cx,
6799            )[0];
6800        });
6801
6802        let snapshot = multibuffer.read(cx).snapshot(cx);
6803
6804        let expected_range = snapshot
6805            .anchor_in_excerpt(
6806                excerpt_1_id,
6807                buffer_1.read(cx).anchor_before(buffer_len / 2),
6808            )
6809            .unwrap()
6810            ..snapshot
6811                .anchor_in_excerpt(excerpt_3_id, buffer_3.read(cx).anchor_after(buffer_len / 2))
6812                .unwrap();
6813
6814        let expected_excerpts = vec![
6815            make_expected_excerpt_info(
6816                &snapshot,
6817                cx,
6818                excerpt_1_id,
6819                &buffer_1,
6820                (buffer_len / 2)..buffer_len,
6821            ),
6822            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, 0..buffer_len),
6823            make_expected_excerpt_info(&snapshot, cx, excerpt_3_id, &buffer_3, 0..buffer_len / 2),
6824        ];
6825
6826        let excerpts = snapshot
6827            .excerpts_in_ranges(vec![expected_range.clone()].into_iter())
6828            .map(|(excerpt_id, buffer, actual_range)| {
6829                (
6830                    excerpt_id,
6831                    buffer.remote_id(),
6832                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6833                )
6834            })
6835            .collect_vec();
6836
6837        validate_excerpts(&excerpts, &expected_excerpts);
6838    }
6839
6840    #[gpui::test]
6841    fn test_excerpts_in_ranges_multiple_ranges(cx: &mut AppContext) {
6842        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6843        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6844        let buffer_len = buffer_1.read(cx).len();
6845        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6846        let mut excerpt_1_id = ExcerptId(0);
6847        let mut excerpt_2_id = ExcerptId(0);
6848
6849        multibuffer.update(cx, |multibuffer, cx| {
6850            excerpt_1_id = multibuffer.push_excerpts(
6851                buffer_1.clone(),
6852                [ExcerptRange {
6853                    context: 0..buffer_1.read(cx).len(),
6854                    primary: None,
6855                }],
6856                cx,
6857            )[0];
6858            excerpt_2_id = multibuffer.push_excerpts(
6859                buffer_2.clone(),
6860                [ExcerptRange {
6861                    context: 0..buffer_2.read(cx).len(),
6862                    primary: None,
6863                }],
6864                cx,
6865            )[0];
6866        });
6867
6868        let snapshot = multibuffer.read(cx).snapshot(cx);
6869
6870        let ranges = vec![
6871            1..(buffer_len / 4),
6872            (buffer_len / 3)..(buffer_len / 2),
6873            (buffer_len / 4 * 3)..(buffer_len),
6874        ];
6875
6876        let expected_excerpts = ranges
6877            .iter()
6878            .map(|range| {
6879                make_expected_excerpt_info(&snapshot, cx, excerpt_1_id, &buffer_1, range.clone())
6880            })
6881            .collect_vec();
6882
6883        let ranges = ranges.into_iter().map(|range| {
6884            map_range_from_excerpt(
6885                &snapshot,
6886                excerpt_1_id,
6887                &buffer_1.read(cx).snapshot(),
6888                range,
6889            )
6890        });
6891
6892        let excerpts = snapshot
6893            .excerpts_in_ranges(ranges)
6894            .map(|(excerpt_id, buffer, actual_range)| {
6895                (
6896                    excerpt_id,
6897                    buffer.remote_id(),
6898                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6899                )
6900            })
6901            .collect_vec();
6902
6903        validate_excerpts(&excerpts, &expected_excerpts);
6904    }
6905
6906    #[gpui::test]
6907    fn test_excerpts_in_ranges_range_ends_at_excerpt_end(cx: &mut AppContext) {
6908        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6909        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6910        let buffer_len = buffer_1.read(cx).len();
6911        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6912        let mut excerpt_1_id = ExcerptId(0);
6913        let mut excerpt_2_id = ExcerptId(0);
6914
6915        multibuffer.update(cx, |multibuffer, cx| {
6916            excerpt_1_id = multibuffer.push_excerpts(
6917                buffer_1.clone(),
6918                [ExcerptRange {
6919                    context: 0..buffer_1.read(cx).len(),
6920                    primary: None,
6921                }],
6922                cx,
6923            )[0];
6924            excerpt_2_id = multibuffer.push_excerpts(
6925                buffer_2.clone(),
6926                [ExcerptRange {
6927                    context: 0..buffer_2.read(cx).len(),
6928                    primary: None,
6929                }],
6930                cx,
6931            )[0];
6932        });
6933
6934        let snapshot = multibuffer.read(cx).snapshot(cx);
6935
6936        let ranges = [0..buffer_len, (buffer_len / 3)..(buffer_len / 2)];
6937
6938        let expected_excerpts = vec![
6939            make_expected_excerpt_info(&snapshot, cx, excerpt_1_id, &buffer_1, ranges[0].clone()),
6940            make_expected_excerpt_info(&snapshot, cx, excerpt_2_id, &buffer_2, ranges[1].clone()),
6941        ];
6942
6943        let ranges = [
6944            map_range_from_excerpt(
6945                &snapshot,
6946                excerpt_1_id,
6947                &buffer_1.read(cx).snapshot(),
6948                ranges[0].clone(),
6949            ),
6950            map_range_from_excerpt(
6951                &snapshot,
6952                excerpt_2_id,
6953                &buffer_2.read(cx).snapshot(),
6954                ranges[1].clone(),
6955            ),
6956        ];
6957
6958        let excerpts = snapshot
6959            .excerpts_in_ranges(ranges.into_iter())
6960            .map(|(excerpt_id, buffer, actual_range)| {
6961                (
6962                    excerpt_id,
6963                    buffer.remote_id(),
6964                    map_range_from_excerpt(&snapshot, excerpt_id, buffer, actual_range),
6965                )
6966            })
6967            .collect_vec();
6968
6969        validate_excerpts(&excerpts, &expected_excerpts);
6970    }
6971
6972    #[gpui::test]
6973    fn test_split_ranges(cx: &mut AppContext) {
6974        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
6975        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
6976        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
6977        multibuffer.update(cx, |multibuffer, cx| {
6978            multibuffer.push_excerpts(
6979                buffer_1.clone(),
6980                [ExcerptRange {
6981                    context: 0..buffer_1.read(cx).len(),
6982                    primary: None,
6983                }],
6984                cx,
6985            );
6986            multibuffer.push_excerpts(
6987                buffer_2.clone(),
6988                [ExcerptRange {
6989                    context: 0..buffer_2.read(cx).len(),
6990                    primary: None,
6991                }],
6992                cx,
6993            );
6994        });
6995
6996        let snapshot = multibuffer.read(cx).snapshot(cx);
6997
6998        let buffer_1_len = buffer_1.read(cx).len();
6999        let buffer_2_len = buffer_2.read(cx).len();
7000        let buffer_1_midpoint = buffer_1_len / 2;
7001        let buffer_2_start = buffer_1_len + '\n'.len_utf8();
7002        let buffer_2_midpoint = buffer_2_start + buffer_2_len / 2;
7003        let total_len = buffer_2_start + buffer_2_len;
7004
7005        let input_ranges = [
7006            0..buffer_1_midpoint,
7007            buffer_1_midpoint..buffer_2_midpoint,
7008            buffer_2_midpoint..total_len,
7009        ]
7010        .map(|range| snapshot.anchor_before(range.start)..snapshot.anchor_after(range.end));
7011
7012        let actual_ranges = snapshot
7013            .split_ranges(input_ranges.into_iter())
7014            .map(|range| range.to_offset(&snapshot))
7015            .collect::<Vec<_>>();
7016
7017        let expected_ranges = vec![
7018            0..buffer_1_midpoint,
7019            buffer_1_midpoint..buffer_1_len,
7020            buffer_2_start..buffer_2_midpoint,
7021            buffer_2_midpoint..total_len,
7022        ];
7023
7024        assert_eq!(actual_ranges, expected_ranges);
7025    }
7026
7027    #[gpui::test]
7028    fn test_split_ranges_single_range_spanning_three_excerpts(cx: &mut AppContext) {
7029        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
7030        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
7031        let buffer_3 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'm'), cx));
7032        let multibuffer = cx.new_model(|_| MultiBuffer::new(Capability::ReadWrite));
7033        multibuffer.update(cx, |multibuffer, cx| {
7034            multibuffer.push_excerpts(
7035                buffer_1.clone(),
7036                [ExcerptRange {
7037                    context: 0..buffer_1.read(cx).len(),
7038                    primary: None,
7039                }],
7040                cx,
7041            );
7042            multibuffer.push_excerpts(
7043                buffer_2.clone(),
7044                [ExcerptRange {
7045                    context: 0..buffer_2.read(cx).len(),
7046                    primary: None,
7047                }],
7048                cx,
7049            );
7050            multibuffer.push_excerpts(
7051                buffer_3.clone(),
7052                [ExcerptRange {
7053                    context: 0..buffer_3.read(cx).len(),
7054                    primary: None,
7055                }],
7056                cx,
7057            );
7058        });
7059
7060        let snapshot = multibuffer.read(cx).snapshot(cx);
7061
7062        let buffer_1_len = buffer_1.read(cx).len();
7063        let buffer_2_len = buffer_2.read(cx).len();
7064        let buffer_3_len = buffer_3.read(cx).len();
7065        let buffer_2_start = buffer_1_len + '\n'.len_utf8();
7066        let buffer_3_start = buffer_2_start + buffer_2_len + '\n'.len_utf8();
7067        let buffer_1_midpoint = buffer_1_len / 2;
7068        let buffer_3_midpoint = buffer_3_start + buffer_3_len / 2;
7069
7070        let input_range =
7071            snapshot.anchor_before(buffer_1_midpoint)..snapshot.anchor_after(buffer_3_midpoint);
7072
7073        let actual_ranges = snapshot
7074            .split_ranges(std::iter::once(input_range))
7075            .map(|range| range.to_offset(&snapshot))
7076            .collect::<Vec<_>>();
7077
7078        let expected_ranges = vec![
7079            buffer_1_midpoint..buffer_1_len,
7080            buffer_2_start..buffer_2_start + buffer_2_len,
7081            buffer_3_start..buffer_3_midpoint,
7082        ];
7083
7084        assert_eq!(actual_ranges, expected_ranges);
7085    }
7086}