multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::{anyhow, Result};
   5use clock::ReplicaId;
   6use collections::{BTreeMap, Bound, HashMap, HashSet};
   7use futures::{channel::mpsc, SinkExt};
   8use git::diff::DiffHunk;
   9use gpui::{AppContext, EventEmitter, Model, ModelContext};
  10pub use language::Completion;
  11use language::{
  12    char_kind,
  13    language_settings::{language_settings, LanguageSettings},
  14    AutoindentMode, Buffer, BufferChunks, BufferSnapshot, Capability, CharKind, Chunk, CursorShape,
  15    DiagnosticEntry, File, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16,
  16    Outline, OutlineItem, Point, PointUtf16, Selection, TextDimension, ToOffset as _,
  17    ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _, TransactionId, Unclipped,
  18};
  19use std::{
  20    borrow::Cow,
  21    cell::{Ref, RefCell},
  22    cmp, fmt,
  23    future::Future,
  24    io,
  25    iter::{self, FromIterator},
  26    mem,
  27    ops::{Range, RangeBounds, Sub},
  28    str,
  29    sync::Arc,
  30    time::{Duration, Instant},
  31};
  32use sum_tree::{Bias, Cursor, SumTree};
  33use text::{
  34    locator::Locator,
  35    subscription::{Subscription, Topic},
  36    BufferId, Edit, TextSummary,
  37};
  38use theme::SyntaxTheme;
  39
  40use util::post_inc;
  41
  42#[cfg(any(test, feature = "test-support"))]
  43use gpui::Context;
  44
  45const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  46
  47#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  48pub struct ExcerptId(usize);
  49
  50/// One or more [`Buffers`](Buffer) being edited in a single view.
  51///
  52/// See <https://zed.dev/features#multi-buffers>
  53pub struct MultiBuffer {
  54    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  55    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  56    snapshot: RefCell<MultiBufferSnapshot>,
  57    /// Contains the state of the buffers being edited
  58    buffers: RefCell<HashMap<BufferId, BufferState>>,
  59    subscriptions: Topic,
  60    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  61    singleton: bool,
  62    replica_id: ReplicaId,
  63    history: History,
  64    title: Option<String>,
  65    capability: Capability,
  66}
  67
  68#[derive(Clone, Debug, PartialEq, Eq)]
  69pub enum Event {
  70    ExcerptsAdded {
  71        buffer: Model<Buffer>,
  72        predecessor: ExcerptId,
  73        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  74    },
  75    ExcerptsRemoved {
  76        ids: Vec<ExcerptId>,
  77    },
  78    ExcerptsEdited {
  79        ids: Vec<ExcerptId>,
  80    },
  81    Edited {
  82        singleton_buffer_edited: bool,
  83    },
  84    TransactionUndone {
  85        transaction_id: TransactionId,
  86    },
  87    Reloaded,
  88    DiffBaseChanged,
  89    LanguageChanged,
  90    CapabilityChanged,
  91    Reparsed,
  92    Saved,
  93    FileHandleChanged,
  94    Closed,
  95    DirtyChanged,
  96    DiagnosticsUpdated,
  97}
  98
  99#[derive(Clone)]
 100struct History {
 101    next_transaction_id: TransactionId,
 102    undo_stack: Vec<Transaction>,
 103    redo_stack: Vec<Transaction>,
 104    transaction_depth: usize,
 105    group_interval: Duration,
 106}
 107
 108#[derive(Clone)]
 109struct Transaction {
 110    id: TransactionId,
 111    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 112    first_edit_at: Instant,
 113    last_edit_at: Instant,
 114    suppress_grouping: bool,
 115}
 116
 117pub trait ToOffset: 'static + fmt::Debug {
 118    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 119}
 120
 121pub trait ToOffsetUtf16: 'static + fmt::Debug {
 122    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 123}
 124
 125pub trait ToPoint: 'static + fmt::Debug {
 126    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 127}
 128
 129pub trait ToPointUtf16: 'static + fmt::Debug {
 130    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 131}
 132
 133struct BufferState {
 134    buffer: Model<Buffer>,
 135    last_version: clock::Global,
 136    last_parse_count: usize,
 137    last_selections_update_count: usize,
 138    last_diagnostics_update_count: usize,
 139    last_file_update_count: usize,
 140    last_git_diff_update_count: usize,
 141    excerpts: Vec<Locator>,
 142    _subscriptions: [gpui::Subscription; 2],
 143}
 144
 145/// The contents of a [`MultiBuffer`] at a single point in time.
 146#[derive(Clone, Default)]
 147pub struct MultiBufferSnapshot {
 148    singleton: bool,
 149    excerpts: SumTree<Excerpt>,
 150    excerpt_ids: SumTree<ExcerptIdMapping>,
 151    parse_count: usize,
 152    diagnostics_update_count: usize,
 153    trailing_excerpt_update_count: usize,
 154    git_diff_update_count: usize,
 155    edit_count: usize,
 156    is_dirty: bool,
 157    has_conflict: bool,
 158}
 159
 160/// A boundary between [`Excerpt`]s in a [`MultiBuffer`]
 161pub struct ExcerptBoundary {
 162    pub id: ExcerptId,
 163    /// The row in the `MultiBuffer` where the boundary is located
 164    pub row: u32,
 165    pub buffer: BufferSnapshot,
 166    pub range: ExcerptRange<text::Anchor>,
 167    /// It's possible to have multiple excerpts in the same buffer,
 168    /// and they are rendered together without a new File header.
 169    ///
 170    /// This flag indicates that the excerpt is the first one in the buffer.
 171    pub starts_new_buffer: bool,
 172}
 173
 174/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 175#[derive(Clone)]
 176struct Excerpt {
 177    /// The unique identifier for this excerpt
 178    id: ExcerptId,
 179    /// The location of the excerpt in the [`MultiBuffer`]
 180    locator: Locator,
 181    /// The buffer being excerpted
 182    buffer_id: BufferId,
 183    /// A snapshot of the buffer being excerpted
 184    buffer: BufferSnapshot,
 185    /// The range of the buffer to be shown in the excerpt
 186    range: ExcerptRange<text::Anchor>,
 187    /// The last row in the excerpted slice of the buffer
 188    max_buffer_row: u32,
 189    /// A summary of the text in the excerpt
 190    text_summary: TextSummary,
 191    has_trailing_newline: bool,
 192}
 193
 194/// A public view into an [`Excerpt`] in a [`MultiBuffer`].
 195///
 196/// Contains methods for getting the [`Buffer`] of the excerpt,
 197/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 198#[derive(Clone)]
 199pub struct MultiBufferExcerpt<'a> {
 200    excerpt: &'a Excerpt,
 201    excerpt_offset: usize,
 202}
 203
 204#[derive(Clone, Debug)]
 205struct ExcerptIdMapping {
 206    id: ExcerptId,
 207    locator: Locator,
 208}
 209
 210/// A range of text from a single [`Buffer`], to be shown as an [`Excerpt`].
 211/// These ranges are relative to the buffer itself
 212#[derive(Clone, Debug, Eq, PartialEq)]
 213pub struct ExcerptRange<T> {
 214    /// The full range of text to be shown in the excerpt.
 215    pub context: Range<T>,
 216    /// The primary range of text to be highlighted in the excerpt.
 217    /// In a multi-buffer search, this would be the text that matched the search
 218    pub primary: Option<Range<T>>,
 219}
 220
 221#[derive(Clone, Debug, Default)]
 222struct ExcerptSummary {
 223    excerpt_id: ExcerptId,
 224    /// The location of the last [`Excerpt`] being summarized
 225    excerpt_locator: Locator,
 226    /// The maximum row of the [`Excerpt`]s being summarized
 227    max_buffer_row: u32,
 228    text: TextSummary,
 229}
 230
 231#[derive(Clone)]
 232pub struct MultiBufferRows<'a> {
 233    buffer_row_range: Range<u32>,
 234    excerpts: Cursor<'a, Excerpt, Point>,
 235}
 236
 237pub struct MultiBufferChunks<'a> {
 238    range: Range<usize>,
 239    excerpts: Cursor<'a, Excerpt, usize>,
 240    excerpt_chunks: Option<ExcerptChunks<'a>>,
 241    language_aware: bool,
 242}
 243
 244pub struct MultiBufferBytes<'a> {
 245    range: Range<usize>,
 246    excerpts: Cursor<'a, Excerpt, usize>,
 247    excerpt_bytes: Option<ExcerptBytes<'a>>,
 248    chunk: &'a [u8],
 249}
 250
 251pub struct ReversedMultiBufferBytes<'a> {
 252    range: Range<usize>,
 253    excerpts: Cursor<'a, Excerpt, usize>,
 254    excerpt_bytes: Option<ExcerptBytes<'a>>,
 255    chunk: &'a [u8],
 256}
 257
 258struct ExcerptChunks<'a> {
 259    content_chunks: BufferChunks<'a>,
 260    footer_height: usize,
 261}
 262
 263struct ExcerptBytes<'a> {
 264    content_bytes: text::Bytes<'a>,
 265    footer_height: usize,
 266}
 267
 268impl MultiBuffer {
 269    pub fn new(replica_id: ReplicaId, capability: Capability) -> Self {
 270        Self {
 271            snapshot: Default::default(),
 272            buffers: Default::default(),
 273            subscriptions: Default::default(),
 274            singleton: false,
 275            capability,
 276            replica_id,
 277            history: History {
 278                next_transaction_id: Default::default(),
 279                undo_stack: Default::default(),
 280                redo_stack: Default::default(),
 281                transaction_depth: 0,
 282                group_interval: Duration::from_millis(300),
 283            },
 284            title: Default::default(),
 285        }
 286    }
 287
 288    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 289        let mut buffers = HashMap::default();
 290        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 291            buffers.insert(
 292                *buffer_id,
 293                BufferState {
 294                    buffer: buffer_state.buffer.clone(),
 295                    last_version: buffer_state.last_version.clone(),
 296                    last_parse_count: buffer_state.last_parse_count,
 297                    last_selections_update_count: buffer_state.last_selections_update_count,
 298                    last_diagnostics_update_count: buffer_state.last_diagnostics_update_count,
 299                    last_file_update_count: buffer_state.last_file_update_count,
 300                    last_git_diff_update_count: buffer_state.last_git_diff_update_count,
 301                    excerpts: buffer_state.excerpts.clone(),
 302                    _subscriptions: [
 303                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 304                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 305                    ],
 306                },
 307            );
 308        }
 309        Self {
 310            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 311            buffers: RefCell::new(buffers),
 312            subscriptions: Default::default(),
 313            singleton: self.singleton,
 314            capability: self.capability,
 315            replica_id: self.replica_id,
 316            history: self.history.clone(),
 317            title: self.title.clone(),
 318        }
 319    }
 320
 321    pub fn with_title(mut self, title: String) -> Self {
 322        self.title = Some(title);
 323        self
 324    }
 325
 326    pub fn read_only(&self) -> bool {
 327        self.capability == Capability::ReadOnly
 328    }
 329
 330    pub fn singleton(buffer: Model<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 331        let mut this = Self::new(buffer.read(cx).replica_id(), buffer.read(cx).capability());
 332        this.singleton = true;
 333        this.push_excerpts(
 334            buffer,
 335            [ExcerptRange {
 336                context: text::Anchor::MIN..text::Anchor::MAX,
 337                primary: None,
 338            }],
 339            cx,
 340        );
 341        this.snapshot.borrow_mut().singleton = true;
 342        this
 343    }
 344
 345    pub fn replica_id(&self) -> ReplicaId {
 346        self.replica_id
 347    }
 348
 349    /// Returns an up-to-date snapshot of the MultiBuffer.
 350    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 351        self.sync(cx);
 352        self.snapshot.borrow().clone()
 353    }
 354
 355    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 356        self.sync(cx);
 357        self.snapshot.borrow()
 358    }
 359
 360    pub fn as_singleton(&self) -> Option<Model<Buffer>> {
 361        if self.singleton {
 362            return Some(
 363                self.buffers
 364                    .borrow()
 365                    .values()
 366                    .next()
 367                    .unwrap()
 368                    .buffer
 369                    .clone(),
 370            );
 371        } else {
 372            None
 373        }
 374    }
 375
 376    pub fn is_singleton(&self) -> bool {
 377        self.singleton
 378    }
 379
 380    pub fn subscribe(&mut self) -> Subscription {
 381        self.subscriptions.subscribe()
 382    }
 383
 384    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 385        self.read(cx).is_dirty()
 386    }
 387
 388    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 389        self.read(cx).has_conflict()
 390    }
 391
 392    // The `is_empty` signature doesn't match what clippy expects
 393    #[allow(clippy::len_without_is_empty)]
 394    pub fn len(&self, cx: &AppContext) -> usize {
 395        self.read(cx).len()
 396    }
 397
 398    pub fn is_empty(&self, cx: &AppContext) -> bool {
 399        self.len(cx) != 0
 400    }
 401
 402    pub fn symbols_containing<T: ToOffset>(
 403        &self,
 404        offset: T,
 405        theme: Option<&SyntaxTheme>,
 406        cx: &AppContext,
 407    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 408        self.read(cx).symbols_containing(offset, theme)
 409    }
 410
 411    pub fn edit<I, S, T>(
 412        &mut self,
 413        edits: I,
 414        mut autoindent_mode: Option<AutoindentMode>,
 415        cx: &mut ModelContext<Self>,
 416    ) where
 417        I: IntoIterator<Item = (Range<S>, T)>,
 418        S: ToOffset,
 419        T: Into<Arc<str>>,
 420    {
 421        if self.buffers.borrow().is_empty() {
 422            return;
 423        }
 424
 425        let snapshot = self.read(cx);
 426        let edits = edits.into_iter().map(|(range, new_text)| {
 427            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 428            if range.start > range.end {
 429                mem::swap(&mut range.start, &mut range.end);
 430            }
 431            (range, new_text)
 432        });
 433
 434        if let Some(buffer) = self.as_singleton() {
 435            return buffer.update(cx, |buffer, cx| {
 436                buffer.edit(edits, autoindent_mode, cx);
 437            });
 438        }
 439
 440        let original_indent_columns = match &mut autoindent_mode {
 441            Some(AutoindentMode::Block {
 442                original_indent_columns,
 443            }) => mem::take(original_indent_columns),
 444            _ => Default::default(),
 445        };
 446
 447        struct BufferEdit {
 448            range: Range<usize>,
 449            new_text: Arc<str>,
 450            is_insertion: bool,
 451            original_indent_column: u32,
 452        }
 453        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 454        let mut edited_excerpt_ids = Vec::new();
 455        let mut cursor = snapshot.excerpts.cursor::<usize>();
 456        for (ix, (range, new_text)) in edits.enumerate() {
 457            let new_text: Arc<str> = new_text.into();
 458            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 459            cursor.seek(&range.start, Bias::Right, &());
 460            if cursor.item().is_none() && range.start == *cursor.start() {
 461                cursor.prev(&());
 462            }
 463            let start_excerpt = cursor.item().expect("start offset out of bounds");
 464            let start_overshoot = range.start - cursor.start();
 465            let buffer_start = start_excerpt
 466                .range
 467                .context
 468                .start
 469                .to_offset(&start_excerpt.buffer)
 470                + start_overshoot;
 471            edited_excerpt_ids.push(start_excerpt.id);
 472
 473            cursor.seek(&range.end, Bias::Right, &());
 474            if cursor.item().is_none() && range.end == *cursor.start() {
 475                cursor.prev(&());
 476            }
 477            let end_excerpt = cursor.item().expect("end offset out of bounds");
 478            let end_overshoot = range.end - cursor.start();
 479            let buffer_end = end_excerpt
 480                .range
 481                .context
 482                .start
 483                .to_offset(&end_excerpt.buffer)
 484                + end_overshoot;
 485
 486            if start_excerpt.id == end_excerpt.id {
 487                buffer_edits
 488                    .entry(start_excerpt.buffer_id)
 489                    .or_insert(Vec::new())
 490                    .push(BufferEdit {
 491                        range: buffer_start..buffer_end,
 492                        new_text,
 493                        is_insertion: true,
 494                        original_indent_column,
 495                    });
 496            } else {
 497                edited_excerpt_ids.push(end_excerpt.id);
 498                let start_excerpt_range = buffer_start
 499                    ..start_excerpt
 500                        .range
 501                        .context
 502                        .end
 503                        .to_offset(&start_excerpt.buffer);
 504                let end_excerpt_range = end_excerpt
 505                    .range
 506                    .context
 507                    .start
 508                    .to_offset(&end_excerpt.buffer)
 509                    ..buffer_end;
 510                buffer_edits
 511                    .entry(start_excerpt.buffer_id)
 512                    .or_insert(Vec::new())
 513                    .push(BufferEdit {
 514                        range: start_excerpt_range,
 515                        new_text: new_text.clone(),
 516                        is_insertion: true,
 517                        original_indent_column,
 518                    });
 519                buffer_edits
 520                    .entry(end_excerpt.buffer_id)
 521                    .or_insert(Vec::new())
 522                    .push(BufferEdit {
 523                        range: end_excerpt_range,
 524                        new_text: new_text.clone(),
 525                        is_insertion: false,
 526                        original_indent_column,
 527                    });
 528
 529                cursor.seek(&range.start, Bias::Right, &());
 530                cursor.next(&());
 531                while let Some(excerpt) = cursor.item() {
 532                    if excerpt.id == end_excerpt.id {
 533                        break;
 534                    }
 535                    buffer_edits
 536                        .entry(excerpt.buffer_id)
 537                        .or_insert(Vec::new())
 538                        .push(BufferEdit {
 539                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 540                            new_text: new_text.clone(),
 541                            is_insertion: false,
 542                            original_indent_column,
 543                        });
 544                    edited_excerpt_ids.push(excerpt.id);
 545                    cursor.next(&());
 546                }
 547            }
 548        }
 549
 550        drop(cursor);
 551        drop(snapshot);
 552        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 553        fn tail(
 554            this: &mut MultiBuffer,
 555            buffer_edits: HashMap<BufferId, Vec<BufferEdit>>,
 556            autoindent_mode: Option<AutoindentMode>,
 557            edited_excerpt_ids: Vec<ExcerptId>,
 558            cx: &mut ModelContext<MultiBuffer>,
 559        ) {
 560            for (buffer_id, mut edits) in buffer_edits {
 561                edits.sort_unstable_by_key(|edit| edit.range.start);
 562                this.buffers.borrow()[&buffer_id]
 563                    .buffer
 564                    .update(cx, |buffer, cx| {
 565                        let mut edits = edits.into_iter().peekable();
 566                        let mut insertions = Vec::new();
 567                        let mut original_indent_columns = Vec::new();
 568                        let mut deletions = Vec::new();
 569                        let empty_str: Arc<str> = "".into();
 570                        while let Some(BufferEdit {
 571                            mut range,
 572                            new_text,
 573                            mut is_insertion,
 574                            original_indent_column,
 575                        }) = edits.next()
 576                        {
 577                            while let Some(BufferEdit {
 578                                range: next_range,
 579                                is_insertion: next_is_insertion,
 580                                ..
 581                            }) = edits.peek()
 582                            {
 583                                if range.end >= next_range.start {
 584                                    range.end = cmp::max(next_range.end, range.end);
 585                                    is_insertion |= *next_is_insertion;
 586                                    edits.next();
 587                                } else {
 588                                    break;
 589                                }
 590                            }
 591
 592                            if is_insertion {
 593                                original_indent_columns.push(original_indent_column);
 594                                insertions.push((
 595                                    buffer.anchor_before(range.start)
 596                                        ..buffer.anchor_before(range.end),
 597                                    new_text.clone(),
 598                                ));
 599                            } else if !range.is_empty() {
 600                                deletions.push((
 601                                    buffer.anchor_before(range.start)
 602                                        ..buffer.anchor_before(range.end),
 603                                    empty_str.clone(),
 604                                ));
 605                            }
 606                        }
 607
 608                        let deletion_autoindent_mode =
 609                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 610                                Some(AutoindentMode::Block {
 611                                    original_indent_columns: Default::default(),
 612                                })
 613                            } else {
 614                                None
 615                            };
 616                        let insertion_autoindent_mode =
 617                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 618                                Some(AutoindentMode::Block {
 619                                    original_indent_columns,
 620                                })
 621                            } else {
 622                                None
 623                            };
 624
 625                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 626                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 627                    })
 628            }
 629
 630            cx.emit(Event::ExcerptsEdited {
 631                ids: edited_excerpt_ids,
 632            });
 633        }
 634        tail(self, buffer_edits, autoindent_mode, edited_excerpt_ids, cx);
 635    }
 636
 637    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 638        self.start_transaction_at(Instant::now(), cx)
 639    }
 640
 641    pub fn start_transaction_at(
 642        &mut self,
 643        now: Instant,
 644        cx: &mut ModelContext<Self>,
 645    ) -> Option<TransactionId> {
 646        if let Some(buffer) = self.as_singleton() {
 647            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 648        }
 649
 650        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 651            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 652        }
 653        self.history.start_transaction(now)
 654    }
 655
 656    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 657        self.end_transaction_at(Instant::now(), cx)
 658    }
 659
 660    pub fn end_transaction_at(
 661        &mut self,
 662        now: Instant,
 663        cx: &mut ModelContext<Self>,
 664    ) -> Option<TransactionId> {
 665        if let Some(buffer) = self.as_singleton() {
 666            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 667        }
 668
 669        let mut buffer_transactions = HashMap::default();
 670        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 671            if let Some(transaction_id) =
 672                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 673            {
 674                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 675            }
 676        }
 677
 678        if self.history.end_transaction(now, buffer_transactions) {
 679            let transaction_id = self.history.group().unwrap();
 680            Some(transaction_id)
 681        } else {
 682            None
 683        }
 684    }
 685
 686    pub fn merge_transactions(
 687        &mut self,
 688        transaction: TransactionId,
 689        destination: TransactionId,
 690        cx: &mut ModelContext<Self>,
 691    ) {
 692        if let Some(buffer) = self.as_singleton() {
 693            buffer.update(cx, |buffer, _| {
 694                buffer.merge_transactions(transaction, destination)
 695            });
 696        } else {
 697            if let Some(transaction) = self.history.forget(transaction) {
 698                if let Some(destination) = self.history.transaction_mut(destination) {
 699                    for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
 700                        if let Some(destination_buffer_transaction_id) =
 701                            destination.buffer_transactions.get(&buffer_id)
 702                        {
 703                            if let Some(state) = self.buffers.borrow().get(&buffer_id) {
 704                                state.buffer.update(cx, |buffer, _| {
 705                                    buffer.merge_transactions(
 706                                        buffer_transaction_id,
 707                                        *destination_buffer_transaction_id,
 708                                    )
 709                                });
 710                            }
 711                        } else {
 712                            destination
 713                                .buffer_transactions
 714                                .insert(buffer_id, buffer_transaction_id);
 715                        }
 716                    }
 717                }
 718            }
 719        }
 720    }
 721
 722    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 723        self.history.finalize_last_transaction();
 724        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 725            buffer.update(cx, |buffer, _| {
 726                buffer.finalize_last_transaction();
 727            });
 728        }
 729    }
 730
 731    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &mut ModelContext<Self>)
 732    where
 733        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
 734    {
 735        self.history
 736            .push_transaction(buffer_transactions, Instant::now(), cx);
 737        self.history.finalize_last_transaction();
 738    }
 739
 740    pub fn group_until_transaction(
 741        &mut self,
 742        transaction_id: TransactionId,
 743        cx: &mut ModelContext<Self>,
 744    ) {
 745        if let Some(buffer) = self.as_singleton() {
 746            buffer.update(cx, |buffer, _| {
 747                buffer.group_until_transaction(transaction_id)
 748            });
 749        } else {
 750            self.history.group_until(transaction_id);
 751        }
 752    }
 753
 754    pub fn set_active_selections(
 755        &mut self,
 756        selections: &[Selection<Anchor>],
 757        line_mode: bool,
 758        cursor_shape: CursorShape,
 759        cx: &mut ModelContext<Self>,
 760    ) {
 761        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
 762            Default::default();
 763        let snapshot = self.read(cx);
 764        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
 765        for selection in selections {
 766            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 767            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 768
 769            cursor.seek(&Some(start_locator), Bias::Left, &());
 770            while let Some(excerpt) = cursor.item() {
 771                if excerpt.locator > *end_locator {
 772                    break;
 773                }
 774
 775                let mut start = excerpt.range.context.start;
 776                let mut end = excerpt.range.context.end;
 777                if excerpt.id == selection.start.excerpt_id {
 778                    start = selection.start.text_anchor;
 779                }
 780                if excerpt.id == selection.end.excerpt_id {
 781                    end = selection.end.text_anchor;
 782                }
 783                selections_by_buffer
 784                    .entry(excerpt.buffer_id)
 785                    .or_default()
 786                    .push(Selection {
 787                        id: selection.id,
 788                        start,
 789                        end,
 790                        reversed: selection.reversed,
 791                        goal: selection.goal,
 792                    });
 793
 794                cursor.next(&());
 795            }
 796        }
 797
 798        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 799            if !selections_by_buffer.contains_key(buffer_id) {
 800                buffer_state
 801                    .buffer
 802                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 803            }
 804        }
 805
 806        for (buffer_id, mut selections) in selections_by_buffer {
 807            self.buffers.borrow()[&buffer_id]
 808                .buffer
 809                .update(cx, |buffer, cx| {
 810                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
 811                    let mut selections = selections.into_iter().peekable();
 812                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 813                        let mut selection = selections.next()?;
 814                        while let Some(next_selection) = selections.peek() {
 815                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
 816                                let next_selection = selections.next().unwrap();
 817                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
 818                                    selection.end = next_selection.end;
 819                                }
 820                            } else {
 821                                break;
 822                            }
 823                        }
 824                        Some(selection)
 825                    }));
 826                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
 827                });
 828        }
 829    }
 830
 831    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 832        for buffer in self.buffers.borrow().values() {
 833            buffer
 834                .buffer
 835                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 836        }
 837    }
 838
 839    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 840        let mut transaction_id = None;
 841        if let Some(buffer) = self.as_singleton() {
 842            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
 843        } else {
 844            while let Some(transaction) = self.history.pop_undo() {
 845                let mut undone = false;
 846                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 847                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 848                        undone |= buffer.update(cx, |buffer, cx| {
 849                            let undo_to = *buffer_transaction_id;
 850                            if let Some(entry) = buffer.peek_undo_stack() {
 851                                *buffer_transaction_id = entry.transaction_id();
 852                            }
 853                            buffer.undo_to_transaction(undo_to, cx)
 854                        });
 855                    }
 856                }
 857
 858                if undone {
 859                    transaction_id = Some(transaction.id);
 860                    break;
 861                }
 862            }
 863        }
 864
 865        if let Some(transaction_id) = transaction_id {
 866            cx.emit(Event::TransactionUndone { transaction_id });
 867        }
 868
 869        transaction_id
 870    }
 871
 872    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 873        if let Some(buffer) = self.as_singleton() {
 874            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 875        }
 876
 877        while let Some(transaction) = self.history.pop_redo() {
 878            let mut redone = false;
 879            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 880                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 881                    redone |= buffer.update(cx, |buffer, cx| {
 882                        let redo_to = *buffer_transaction_id;
 883                        if let Some(entry) = buffer.peek_redo_stack() {
 884                            *buffer_transaction_id = entry.transaction_id();
 885                        }
 886                        buffer.redo_to_transaction(redo_to, cx)
 887                    });
 888                }
 889            }
 890
 891            if redone {
 892                return Some(transaction.id);
 893            }
 894        }
 895
 896        None
 897    }
 898
 899    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
 900        if let Some(buffer) = self.as_singleton() {
 901            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
 902        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
 903            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
 904                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 905                    buffer.update(cx, |buffer, cx| {
 906                        buffer.undo_transaction(*transaction_id, cx)
 907                    });
 908                }
 909            }
 910        }
 911    }
 912
 913    pub fn stream_excerpts_with_context_lines(
 914        &mut self,
 915        buffer: Model<Buffer>,
 916        ranges: Vec<Range<text::Anchor>>,
 917        context_line_count: u32,
 918        cx: &mut ModelContext<Self>,
 919    ) -> mpsc::Receiver<Range<Anchor>> {
 920        let (buffer_id, buffer_snapshot) =
 921            buffer.update(cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
 922
 923        let (mut tx, rx) = mpsc::channel(256);
 924        cx.spawn(move |this, mut cx| async move {
 925            let mut excerpt_ranges = Vec::new();
 926            let mut range_counts = Vec::new();
 927            cx.background_executor()
 928                .scoped(|scope| {
 929                    scope.spawn(async {
 930                        let (ranges, counts) =
 931                            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 932                        excerpt_ranges = ranges;
 933                        range_counts = counts;
 934                    });
 935                })
 936                .await;
 937
 938            let mut ranges = ranges.into_iter();
 939            let mut range_counts = range_counts.into_iter();
 940            for excerpt_ranges in excerpt_ranges.chunks(100) {
 941                let excerpt_ids = match this.update(&mut cx, |this, cx| {
 942                    this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
 943                }) {
 944                    Ok(excerpt_ids) => excerpt_ids,
 945                    Err(_) => return,
 946                };
 947
 948                for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.by_ref())
 949                {
 950                    for range in ranges.by_ref().take(range_count) {
 951                        let start = Anchor {
 952                            buffer_id: Some(buffer_id),
 953                            excerpt_id: excerpt_id,
 954                            text_anchor: range.start,
 955                        };
 956                        let end = Anchor {
 957                            buffer_id: Some(buffer_id),
 958                            excerpt_id: excerpt_id,
 959                            text_anchor: range.end,
 960                        };
 961                        if tx.send(start..end).await.is_err() {
 962                            break;
 963                        }
 964                    }
 965                }
 966            }
 967        })
 968        .detach();
 969
 970        rx
 971    }
 972
 973    pub fn push_excerpts<O>(
 974        &mut self,
 975        buffer: Model<Buffer>,
 976        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
 977        cx: &mut ModelContext<Self>,
 978    ) -> Vec<ExcerptId>
 979    where
 980        O: text::ToOffset,
 981    {
 982        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
 983    }
 984
 985    pub fn push_excerpts_with_context_lines<O>(
 986        &mut self,
 987        buffer: Model<Buffer>,
 988        ranges: Vec<Range<O>>,
 989        context_line_count: u32,
 990        cx: &mut ModelContext<Self>,
 991    ) -> Vec<Range<Anchor>>
 992    where
 993        O: text::ToPoint + text::ToOffset,
 994    {
 995        let buffer_id = buffer.read(cx).remote_id();
 996        let buffer_snapshot = buffer.read(cx).snapshot();
 997        let (excerpt_ranges, range_counts) =
 998            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 999
1000        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
1001
1002        let mut anchor_ranges = Vec::new();
1003        let mut ranges = ranges.into_iter();
1004        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
1005            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
1006                let start = Anchor {
1007                    buffer_id: Some(buffer_id),
1008                    excerpt_id: excerpt_id,
1009                    text_anchor: buffer_snapshot.anchor_after(range.start),
1010                };
1011                let end = Anchor {
1012                    buffer_id: Some(buffer_id),
1013                    excerpt_id: excerpt_id,
1014                    text_anchor: buffer_snapshot.anchor_after(range.end),
1015                };
1016                start..end
1017            }))
1018        }
1019        anchor_ranges
1020    }
1021
1022    pub fn insert_excerpts_after<O>(
1023        &mut self,
1024        prev_excerpt_id: ExcerptId,
1025        buffer: Model<Buffer>,
1026        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1027        cx: &mut ModelContext<Self>,
1028    ) -> Vec<ExcerptId>
1029    where
1030        O: text::ToOffset,
1031    {
1032        let mut ids = Vec::new();
1033        let mut next_excerpt_id =
1034            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1035                last_entry.id.0 + 1
1036            } else {
1037                1
1038            };
1039        self.insert_excerpts_with_ids_after(
1040            prev_excerpt_id,
1041            buffer,
1042            ranges.into_iter().map(|range| {
1043                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1044                ids.push(id);
1045                (id, range)
1046            }),
1047            cx,
1048        );
1049        ids
1050    }
1051
1052    pub fn insert_excerpts_with_ids_after<O>(
1053        &mut self,
1054        prev_excerpt_id: ExcerptId,
1055        buffer: Model<Buffer>,
1056        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1057        cx: &mut ModelContext<Self>,
1058    ) where
1059        O: text::ToOffset,
1060    {
1061        assert_eq!(self.history.transaction_depth, 0);
1062        let mut ranges = ranges.into_iter().peekable();
1063        if ranges.peek().is_none() {
1064            return Default::default();
1065        }
1066
1067        self.sync(cx);
1068
1069        let buffer_id = buffer.read(cx).remote_id();
1070        let buffer_snapshot = buffer.read(cx).snapshot();
1071
1072        let mut buffers = self.buffers.borrow_mut();
1073        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
1074            last_version: buffer_snapshot.version().clone(),
1075            last_parse_count: buffer_snapshot.parse_count(),
1076            last_selections_update_count: buffer_snapshot.selections_update_count(),
1077            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
1078            last_file_update_count: buffer_snapshot.file_update_count(),
1079            last_git_diff_update_count: buffer_snapshot.git_diff_update_count(),
1080            excerpts: Default::default(),
1081            _subscriptions: [
1082                cx.observe(&buffer, |_, _, cx| cx.notify()),
1083                cx.subscribe(&buffer, Self::on_buffer_event),
1084            ],
1085            buffer: buffer.clone(),
1086        });
1087
1088        let mut snapshot = self.snapshot.borrow_mut();
1089
1090        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1091        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1092        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1093        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
1094        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1095
1096        let edit_start = new_excerpts.summary().text.len;
1097        new_excerpts.update_last(
1098            |excerpt| {
1099                excerpt.has_trailing_newline = true;
1100            },
1101            &(),
1102        );
1103
1104        let next_locator = if let Some(excerpt) = cursor.item() {
1105            excerpt.locator.clone()
1106        } else {
1107            Locator::max()
1108        };
1109
1110        let mut excerpts = Vec::new();
1111        while let Some((id, range)) = ranges.next() {
1112            let locator = Locator::between(&prev_locator, &next_locator);
1113            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1114                buffer_state.excerpts.insert(ix, locator.clone());
1115            }
1116            let range = ExcerptRange {
1117                context: buffer_snapshot.anchor_before(&range.context.start)
1118                    ..buffer_snapshot.anchor_after(&range.context.end),
1119                primary: range.primary.map(|primary| {
1120                    buffer_snapshot.anchor_before(&primary.start)
1121                        ..buffer_snapshot.anchor_after(&primary.end)
1122                }),
1123            };
1124            excerpts.push((id, range.clone()));
1125            let excerpt = Excerpt::new(
1126                id,
1127                locator.clone(),
1128                buffer_id,
1129                buffer_snapshot.clone(),
1130                range,
1131                ranges.peek().is_some() || cursor.item().is_some(),
1132            );
1133            new_excerpts.push(excerpt, &());
1134            prev_locator = locator.clone();
1135
1136            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1137                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1138            }
1139            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
1140        }
1141
1142        let edit_end = new_excerpts.summary().text.len;
1143
1144        let suffix = cursor.suffix(&());
1145        let changed_trailing_excerpt = suffix.is_empty();
1146        new_excerpts.append(suffix, &());
1147        drop(cursor);
1148        snapshot.excerpts = new_excerpts;
1149        snapshot.excerpt_ids = new_excerpt_ids;
1150        if changed_trailing_excerpt {
1151            snapshot.trailing_excerpt_update_count += 1;
1152        }
1153
1154        self.subscriptions.publish_mut([Edit {
1155            old: edit_start..edit_start,
1156            new: edit_start..edit_end,
1157        }]);
1158        cx.emit(Event::Edited {
1159            singleton_buffer_edited: false,
1160        });
1161        cx.emit(Event::ExcerptsAdded {
1162            buffer,
1163            predecessor: prev_excerpt_id,
1164            excerpts,
1165        });
1166        cx.notify();
1167    }
1168
1169    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1170        self.sync(cx);
1171        let ids = self.excerpt_ids();
1172        self.buffers.borrow_mut().clear();
1173        let mut snapshot = self.snapshot.borrow_mut();
1174        let prev_len = snapshot.len();
1175        snapshot.excerpts = Default::default();
1176        snapshot.trailing_excerpt_update_count += 1;
1177        snapshot.is_dirty = false;
1178        snapshot.has_conflict = false;
1179
1180        self.subscriptions.publish_mut([Edit {
1181            old: 0..prev_len,
1182            new: 0..0,
1183        }]);
1184        cx.emit(Event::Edited {
1185            singleton_buffer_edited: false,
1186        });
1187        cx.emit(Event::ExcerptsRemoved { ids });
1188        cx.notify();
1189    }
1190
1191    pub fn excerpts_for_buffer(
1192        &self,
1193        buffer: &Model<Buffer>,
1194        cx: &AppContext,
1195    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1196        let mut excerpts = Vec::new();
1197        let snapshot = self.read(cx);
1198        let buffers = self.buffers.borrow();
1199        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1200        for locator in buffers
1201            .get(&buffer.read(cx).remote_id())
1202            .map(|state| &state.excerpts)
1203            .into_iter()
1204            .flatten()
1205        {
1206            cursor.seek_forward(&Some(locator), Bias::Left, &());
1207            if let Some(excerpt) = cursor.item() {
1208                if excerpt.locator == *locator {
1209                    excerpts.push((excerpt.id, excerpt.range.clone()));
1210                }
1211            }
1212        }
1213
1214        excerpts
1215    }
1216
1217    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1218        self.snapshot
1219            .borrow()
1220            .excerpts
1221            .iter()
1222            .map(|entry| entry.id)
1223            .collect()
1224    }
1225
1226    pub fn excerpt_containing(
1227        &self,
1228        position: impl ToOffset,
1229        cx: &AppContext,
1230    ) -> Option<(ExcerptId, Model<Buffer>, Range<text::Anchor>)> {
1231        let snapshot = self.read(cx);
1232        let position = position.to_offset(&snapshot);
1233
1234        let mut cursor = snapshot.excerpts.cursor::<usize>();
1235        cursor.seek(&position, Bias::Right, &());
1236        cursor
1237            .item()
1238            .or_else(|| snapshot.excerpts.last())
1239            .map(|excerpt| {
1240                (
1241                    excerpt.id,
1242                    self.buffers
1243                        .borrow()
1244                        .get(&excerpt.buffer_id)
1245                        .unwrap()
1246                        .buffer
1247                        .clone(),
1248                    excerpt.range.context.clone(),
1249                )
1250            })
1251    }
1252
1253    // If point is at the end of the buffer, the last excerpt is returned
1254    pub fn point_to_buffer_offset<T: ToOffset>(
1255        &self,
1256        point: T,
1257        cx: &AppContext,
1258    ) -> Option<(Model<Buffer>, usize, ExcerptId)> {
1259        let snapshot = self.read(cx);
1260        let offset = point.to_offset(&snapshot);
1261        let mut cursor = snapshot.excerpts.cursor::<usize>();
1262        cursor.seek(&offset, Bias::Right, &());
1263        if cursor.item().is_none() {
1264            cursor.prev(&());
1265        }
1266
1267        cursor.item().map(|excerpt| {
1268            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1269            let buffer_point = excerpt_start + offset - *cursor.start();
1270            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1271
1272            (buffer, buffer_point, excerpt.id)
1273        })
1274    }
1275
1276    pub fn range_to_buffer_ranges<T: ToOffset>(
1277        &self,
1278        range: Range<T>,
1279        cx: &AppContext,
1280    ) -> Vec<(Model<Buffer>, Range<usize>, ExcerptId)> {
1281        let snapshot = self.read(cx);
1282        let start = range.start.to_offset(&snapshot);
1283        let end = range.end.to_offset(&snapshot);
1284
1285        let mut result = Vec::new();
1286        let mut cursor = snapshot.excerpts.cursor::<usize>();
1287        cursor.seek(&start, Bias::Right, &());
1288        if cursor.item().is_none() {
1289            cursor.prev(&());
1290        }
1291
1292        while let Some(excerpt) = cursor.item() {
1293            if *cursor.start() > end {
1294                break;
1295            }
1296
1297            let mut end_before_newline = cursor.end(&());
1298            if excerpt.has_trailing_newline {
1299                end_before_newline -= 1;
1300            }
1301            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1302            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1303            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1304            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1305            result.push((buffer, start..end, excerpt.id));
1306            cursor.next(&());
1307        }
1308
1309        result
1310    }
1311
1312    pub fn remove_excerpts(
1313        &mut self,
1314        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1315        cx: &mut ModelContext<Self>,
1316    ) {
1317        self.sync(cx);
1318        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1319        if ids.is_empty() {
1320            return;
1321        }
1322
1323        let mut buffers = self.buffers.borrow_mut();
1324        let mut snapshot = self.snapshot.borrow_mut();
1325        let mut new_excerpts = SumTree::new();
1326        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1327        let mut edits = Vec::new();
1328        let mut excerpt_ids = ids.iter().copied().peekable();
1329
1330        while let Some(excerpt_id) = excerpt_ids.next() {
1331            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1332            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1333            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1334
1335            if let Some(mut excerpt) = cursor.item() {
1336                if excerpt.id != excerpt_id {
1337                    continue;
1338                }
1339                let mut old_start = cursor.start().1;
1340
1341                // Skip over the removed excerpt.
1342                'remove_excerpts: loop {
1343                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1344                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1345                        if buffer_state.excerpts.is_empty() {
1346                            buffers.remove(&excerpt.buffer_id);
1347                        }
1348                    }
1349                    cursor.next(&());
1350
1351                    // Skip over any subsequent excerpts that are also removed.
1352                    while let Some(&next_excerpt_id) = excerpt_ids.peek() {
1353                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1354                        if let Some(next_excerpt) = cursor.item() {
1355                            if next_excerpt.locator == *next_locator {
1356                                excerpt_ids.next();
1357                                excerpt = next_excerpt;
1358                                continue 'remove_excerpts;
1359                            }
1360                        }
1361                        break;
1362                    }
1363
1364                    break;
1365                }
1366
1367                // When removing the last excerpt, remove the trailing newline from
1368                // the previous excerpt.
1369                if cursor.item().is_none() && old_start > 0 {
1370                    old_start -= 1;
1371                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1372                }
1373
1374                // Push an edit for the removal of this run of excerpts.
1375                let old_end = cursor.start().1;
1376                let new_start = new_excerpts.summary().text.len;
1377                edits.push(Edit {
1378                    old: old_start..old_end,
1379                    new: new_start..new_start,
1380                });
1381            }
1382        }
1383        let suffix = cursor.suffix(&());
1384        let changed_trailing_excerpt = suffix.is_empty();
1385        new_excerpts.append(suffix, &());
1386        drop(cursor);
1387        snapshot.excerpts = new_excerpts;
1388
1389        if changed_trailing_excerpt {
1390            snapshot.trailing_excerpt_update_count += 1;
1391        }
1392
1393        self.subscriptions.publish_mut(edits);
1394        cx.emit(Event::Edited {
1395            singleton_buffer_edited: false,
1396        });
1397        cx.emit(Event::ExcerptsRemoved { ids });
1398        cx.notify();
1399    }
1400
1401    pub fn wait_for_anchors<'a>(
1402        &self,
1403        anchors: impl 'a + Iterator<Item = Anchor>,
1404        cx: &mut ModelContext<Self>,
1405    ) -> impl 'static + Future<Output = Result<()>> {
1406        let borrow = self.buffers.borrow();
1407        let mut error = None;
1408        let mut futures = Vec::new();
1409        for anchor in anchors {
1410            if let Some(buffer_id) = anchor.buffer_id {
1411                if let Some(buffer) = borrow.get(&buffer_id) {
1412                    buffer.buffer.update(cx, |buffer, _| {
1413                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1414                    });
1415                } else {
1416                    error = Some(anyhow!(
1417                        "buffer {buffer_id} is not part of this multi-buffer"
1418                    ));
1419                    break;
1420                }
1421            }
1422        }
1423        async move {
1424            if let Some(error) = error {
1425                Err(error)?;
1426            }
1427            for future in futures {
1428                future.await?;
1429            }
1430            Ok(())
1431        }
1432    }
1433
1434    pub fn text_anchor_for_position<T: ToOffset>(
1435        &self,
1436        position: T,
1437        cx: &AppContext,
1438    ) -> Option<(Model<Buffer>, language::Anchor)> {
1439        let snapshot = self.read(cx);
1440        let anchor = snapshot.anchor_before(position);
1441        let buffer = self
1442            .buffers
1443            .borrow()
1444            .get(&anchor.buffer_id?)?
1445            .buffer
1446            .clone();
1447        Some((buffer, anchor.text_anchor))
1448    }
1449
1450    fn on_buffer_event(
1451        &mut self,
1452        buffer: Model<Buffer>,
1453        event: &language::Event,
1454        cx: &mut ModelContext<Self>,
1455    ) {
1456        cx.emit(match event {
1457            language::Event::Edited => Event::Edited {
1458                singleton_buffer_edited: true,
1459            },
1460            language::Event::DirtyChanged => Event::DirtyChanged,
1461            language::Event::Saved => Event::Saved,
1462            language::Event::FileHandleChanged => Event::FileHandleChanged,
1463            language::Event::Reloaded => Event::Reloaded,
1464            language::Event::DiffBaseChanged => Event::DiffBaseChanged,
1465            language::Event::LanguageChanged => Event::LanguageChanged,
1466            language::Event::Reparsed => Event::Reparsed,
1467            language::Event::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1468            language::Event::Closed => Event::Closed,
1469            language::Event::CapabilityChanged => {
1470                self.capability = buffer.read(cx).capability();
1471                Event::CapabilityChanged
1472            }
1473
1474            //
1475            language::Event::Operation(_) => return,
1476        });
1477    }
1478
1479    pub fn all_buffers(&self) -> HashSet<Model<Buffer>> {
1480        self.buffers
1481            .borrow()
1482            .values()
1483            .map(|state| state.buffer.clone())
1484            .collect()
1485    }
1486
1487    pub fn buffer(&self, buffer_id: BufferId) -> Option<Model<Buffer>> {
1488        self.buffers
1489            .borrow()
1490            .get(&buffer_id)
1491            .map(|state| state.buffer.clone())
1492    }
1493
1494    pub fn is_completion_trigger(&self, position: Anchor, text: &str, cx: &AppContext) -> bool {
1495        let mut chars = text.chars();
1496        let char = if let Some(char) = chars.next() {
1497            char
1498        } else {
1499            return false;
1500        };
1501        if chars.next().is_some() {
1502            return false;
1503        }
1504
1505        let snapshot = self.snapshot(cx);
1506        let position = position.to_offset(&snapshot);
1507        let scope = snapshot.language_scope_at(position);
1508        if char_kind(&scope, char) == CharKind::Word {
1509            return true;
1510        }
1511
1512        let anchor = snapshot.anchor_before(position);
1513        anchor
1514            .buffer_id
1515            .and_then(|buffer_id| {
1516                let buffer = self.buffers.borrow().get(&buffer_id)?.buffer.clone();
1517                Some(
1518                    buffer
1519                        .read(cx)
1520                        .completion_triggers()
1521                        .iter()
1522                        .any(|string| string == text),
1523                )
1524            })
1525            .unwrap_or(false)
1526    }
1527
1528    pub fn language_at<T: ToOffset>(&self, point: T, cx: &AppContext) -> Option<Arc<Language>> {
1529        self.point_to_buffer_offset(point, cx)
1530            .and_then(|(buffer, offset, _)| buffer.read(cx).language_at(offset))
1531    }
1532
1533    pub fn settings_at<'a, T: ToOffset>(
1534        &self,
1535        point: T,
1536        cx: &'a AppContext,
1537    ) -> &'a LanguageSettings {
1538        let mut language = None;
1539        let mut file = None;
1540        if let Some((buffer, offset, _)) = self.point_to_buffer_offset(point, cx) {
1541            let buffer = buffer.read(cx);
1542            language = buffer.language_at(offset);
1543            file = buffer.file();
1544        }
1545        language_settings(language.as_ref(), file, cx)
1546    }
1547
1548    pub fn for_each_buffer(&self, mut f: impl FnMut(&Model<Buffer>)) {
1549        self.buffers
1550            .borrow()
1551            .values()
1552            .for_each(|state| f(&state.buffer))
1553    }
1554
1555    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1556        if let Some(title) = self.title.as_ref() {
1557            return title.into();
1558        }
1559
1560        if let Some(buffer) = self.as_singleton() {
1561            if let Some(file) = buffer.read(cx).file() {
1562                return file.file_name(cx).to_string_lossy();
1563            }
1564        }
1565
1566        "untitled".into()
1567    }
1568
1569    #[cfg(any(test, feature = "test-support"))]
1570    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1571        self.as_singleton().unwrap().read(cx).is_parsing()
1572    }
1573
1574    fn sync(&self, cx: &AppContext) {
1575        let mut snapshot = self.snapshot.borrow_mut();
1576        let mut excerpts_to_edit = Vec::new();
1577        let mut reparsed = false;
1578        let mut diagnostics_updated = false;
1579        let mut git_diff_updated = false;
1580        let mut is_dirty = false;
1581        let mut has_conflict = false;
1582        let mut edited = false;
1583        let mut buffers = self.buffers.borrow_mut();
1584        for buffer_state in buffers.values_mut() {
1585            let buffer = buffer_state.buffer.read(cx);
1586            let version = buffer.version();
1587            let parse_count = buffer.parse_count();
1588            let selections_update_count = buffer.selections_update_count();
1589            let diagnostics_update_count = buffer.diagnostics_update_count();
1590            let file_update_count = buffer.file_update_count();
1591            let git_diff_update_count = buffer.git_diff_update_count();
1592
1593            let buffer_edited = version.changed_since(&buffer_state.last_version);
1594            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1595            let buffer_selections_updated =
1596                selections_update_count > buffer_state.last_selections_update_count;
1597            let buffer_diagnostics_updated =
1598                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1599            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1600            let buffer_git_diff_updated =
1601                git_diff_update_count > buffer_state.last_git_diff_update_count;
1602            if buffer_edited
1603                || buffer_reparsed
1604                || buffer_selections_updated
1605                || buffer_diagnostics_updated
1606                || buffer_file_updated
1607                || buffer_git_diff_updated
1608            {
1609                buffer_state.last_version = version;
1610                buffer_state.last_parse_count = parse_count;
1611                buffer_state.last_selections_update_count = selections_update_count;
1612                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1613                buffer_state.last_file_update_count = file_update_count;
1614                buffer_state.last_git_diff_update_count = git_diff_update_count;
1615                excerpts_to_edit.extend(
1616                    buffer_state
1617                        .excerpts
1618                        .iter()
1619                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
1620                );
1621            }
1622
1623            edited |= buffer_edited;
1624            reparsed |= buffer_reparsed;
1625            diagnostics_updated |= buffer_diagnostics_updated;
1626            git_diff_updated |= buffer_git_diff_updated;
1627            is_dirty |= buffer.is_dirty();
1628            has_conflict |= buffer.has_conflict();
1629        }
1630        if edited {
1631            snapshot.edit_count += 1;
1632        }
1633        if reparsed {
1634            snapshot.parse_count += 1;
1635        }
1636        if diagnostics_updated {
1637            snapshot.diagnostics_update_count += 1;
1638        }
1639        if git_diff_updated {
1640            snapshot.git_diff_update_count += 1;
1641        }
1642        snapshot.is_dirty = is_dirty;
1643        snapshot.has_conflict = has_conflict;
1644
1645        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
1646
1647        let mut edits = Vec::new();
1648        let mut new_excerpts = SumTree::new();
1649        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1650
1651        for (locator, buffer, buffer_edited) in excerpts_to_edit {
1652            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1653            let old_excerpt = cursor.item().unwrap();
1654            let buffer = buffer.read(cx);
1655            let buffer_id = buffer.remote_id();
1656
1657            let mut new_excerpt;
1658            if buffer_edited {
1659                edits.extend(
1660                    buffer
1661                        .edits_since_in_range::<usize>(
1662                            old_excerpt.buffer.version(),
1663                            old_excerpt.range.context.clone(),
1664                        )
1665                        .map(|mut edit| {
1666                            let excerpt_old_start = cursor.start().1;
1667                            let excerpt_new_start = new_excerpts.summary().text.len;
1668                            edit.old.start += excerpt_old_start;
1669                            edit.old.end += excerpt_old_start;
1670                            edit.new.start += excerpt_new_start;
1671                            edit.new.end += excerpt_new_start;
1672                            edit
1673                        }),
1674                );
1675
1676                new_excerpt = Excerpt::new(
1677                    old_excerpt.id,
1678                    locator.clone(),
1679                    buffer_id,
1680                    buffer.snapshot(),
1681                    old_excerpt.range.clone(),
1682                    old_excerpt.has_trailing_newline,
1683                );
1684            } else {
1685                new_excerpt = old_excerpt.clone();
1686                new_excerpt.buffer = buffer.snapshot();
1687            }
1688
1689            new_excerpts.push(new_excerpt, &());
1690            cursor.next(&());
1691        }
1692        new_excerpts.append(cursor.suffix(&()), &());
1693
1694        drop(cursor);
1695        snapshot.excerpts = new_excerpts;
1696
1697        self.subscriptions.publish(edits);
1698    }
1699}
1700
1701#[cfg(any(test, feature = "test-support"))]
1702impl MultiBuffer {
1703    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> Model<Self> {
1704        let buffer = cx
1705            .new_model(|cx| Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text));
1706        cx.new_model(|cx| Self::singleton(buffer, cx))
1707    }
1708
1709    pub fn build_multi<const COUNT: usize>(
1710        excerpts: [(&str, Vec<Range<Point>>); COUNT],
1711        cx: &mut gpui::AppContext,
1712    ) -> Model<Self> {
1713        let multi = cx.new_model(|_| Self::new(0, Capability::ReadWrite));
1714        for (text, ranges) in excerpts {
1715            let buffer = cx.new_model(|cx| {
1716                Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text)
1717            });
1718            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
1719                context: range,
1720                primary: None,
1721            });
1722            multi.update(cx, |multi, cx| {
1723                multi.push_excerpts(buffer, excerpt_ranges, cx)
1724            });
1725        }
1726
1727        multi
1728    }
1729
1730    pub fn build_from_buffer(buffer: Model<Buffer>, cx: &mut gpui::AppContext) -> Model<Self> {
1731        cx.new_model(|cx| Self::singleton(buffer, cx))
1732    }
1733
1734    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> Model<Self> {
1735        cx.new_model(|cx| {
1736            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
1737            let mutation_count = rng.gen_range(1..=5);
1738            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
1739            multibuffer
1740        })
1741    }
1742
1743    pub fn randomly_edit(
1744        &mut self,
1745        rng: &mut impl rand::Rng,
1746        edit_count: usize,
1747        cx: &mut ModelContext<Self>,
1748    ) {
1749        use util::RandomCharIter;
1750
1751        let snapshot = self.read(cx);
1752        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1753        let mut last_end = None;
1754        for _ in 0..edit_count {
1755            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
1756                break;
1757            }
1758
1759            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1760            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
1761            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
1762            last_end = Some(end);
1763
1764            let mut range = start..end;
1765            if rng.gen_bool(0.2) {
1766                mem::swap(&mut range.start, &mut range.end);
1767            }
1768
1769            let new_text_len = rng.gen_range(0..10);
1770            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1771
1772            edits.push((range, new_text.into()));
1773        }
1774        log::info!("mutating multi-buffer with {:?}", edits);
1775        drop(snapshot);
1776
1777        self.edit(edits, None, cx);
1778    }
1779
1780    pub fn randomly_edit_excerpts(
1781        &mut self,
1782        rng: &mut impl rand::Rng,
1783        mutation_count: usize,
1784        cx: &mut ModelContext<Self>,
1785    ) {
1786        use rand::prelude::*;
1787        use std::env;
1788        use util::RandomCharIter;
1789
1790        let max_excerpts = env::var("MAX_EXCERPTS")
1791            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1792            .unwrap_or(5);
1793
1794        let mut buffers = Vec::new();
1795        for _ in 0..mutation_count {
1796            if rng.gen_bool(0.05) {
1797                log::info!("Clearing multi-buffer");
1798                self.clear(cx);
1799                continue;
1800            }
1801
1802            let excerpt_ids = self.excerpt_ids();
1803            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1804                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1805                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1806                    buffers.push(cx.new_model(|cx| {
1807                        Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text)
1808                    }));
1809                    let buffer = buffers.last().unwrap().read(cx);
1810                    log::info!(
1811                        "Creating new buffer {} with text: {:?}",
1812                        buffer.remote_id(),
1813                        buffer.text()
1814                    );
1815                    buffers.last().unwrap().clone()
1816                } else {
1817                    self.buffers
1818                        .borrow()
1819                        .values()
1820                        .choose(rng)
1821                        .unwrap()
1822                        .buffer
1823                        .clone()
1824                };
1825
1826                let buffer = buffer_handle.read(cx);
1827                let buffer_text = buffer.text();
1828                let ranges = (0..rng.gen_range(0..5))
1829                    .map(|_| {
1830                        let end_ix =
1831                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1832                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1833                        ExcerptRange {
1834                            context: start_ix..end_ix,
1835                            primary: None,
1836                        }
1837                    })
1838                    .collect::<Vec<_>>();
1839                log::info!(
1840                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
1841                    buffer_handle.read(cx).remote_id(),
1842                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
1843                    ranges
1844                        .iter()
1845                        .map(|r| &buffer_text[r.context.clone()])
1846                        .collect::<Vec<_>>()
1847                );
1848
1849                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
1850                log::info!("Inserted with ids: {:?}", excerpt_id);
1851            } else {
1852                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1853                let mut excerpts_to_remove = excerpt_ids
1854                    .choose_multiple(rng, remove_count)
1855                    .cloned()
1856                    .collect::<Vec<_>>();
1857                let snapshot = self.snapshot.borrow();
1858                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
1859                drop(snapshot);
1860                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1861                self.remove_excerpts(excerpts_to_remove, cx);
1862            }
1863        }
1864    }
1865
1866    pub fn randomly_mutate(
1867        &mut self,
1868        rng: &mut impl rand::Rng,
1869        mutation_count: usize,
1870        cx: &mut ModelContext<Self>,
1871    ) {
1872        use rand::prelude::*;
1873
1874        if rng.gen_bool(0.7) || self.singleton {
1875            let buffer = self
1876                .buffers
1877                .borrow()
1878                .values()
1879                .choose(rng)
1880                .map(|state| state.buffer.clone());
1881
1882            if let Some(buffer) = buffer {
1883                buffer.update(cx, |buffer, cx| {
1884                    if rng.gen() {
1885                        buffer.randomly_edit(rng, mutation_count, cx);
1886                    } else {
1887                        buffer.randomly_undo_redo(rng, cx);
1888                    }
1889                });
1890            } else {
1891                self.randomly_edit(rng, mutation_count, cx);
1892            }
1893        } else {
1894            self.randomly_edit_excerpts(rng, mutation_count, cx);
1895        }
1896
1897        self.check_invariants(cx);
1898    }
1899
1900    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
1901        let snapshot = self.read(cx);
1902        let excerpts = snapshot.excerpts.items(&());
1903        let excerpt_ids = snapshot.excerpt_ids.items(&());
1904
1905        for (ix, excerpt) in excerpts.iter().enumerate() {
1906            if ix == 0 {
1907                if excerpt.locator <= Locator::min() {
1908                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
1909                }
1910            } else {
1911                if excerpt.locator <= excerpts[ix - 1].locator {
1912                    panic!("excerpts are out-of-order: {:?}", excerpts);
1913                }
1914            }
1915        }
1916
1917        for (ix, entry) in excerpt_ids.iter().enumerate() {
1918            if ix == 0 {
1919                if entry.id.cmp(&ExcerptId::min(), &snapshot).is_le() {
1920                    panic!("invalid first excerpt id {:?}", entry.id);
1921                }
1922            } else {
1923                if entry.id <= excerpt_ids[ix - 1].id {
1924                    panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
1925                }
1926            }
1927        }
1928    }
1929}
1930
1931impl EventEmitter<Event> for MultiBuffer {}
1932
1933impl MultiBufferSnapshot {
1934    pub fn text(&self) -> String {
1935        self.chunks(0..self.len(), false)
1936            .map(|chunk| chunk.text)
1937            .collect()
1938    }
1939
1940    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1941        let mut offset = position.to_offset(self);
1942        let mut cursor = self.excerpts.cursor::<usize>();
1943        cursor.seek(&offset, Bias::Left, &());
1944        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1945            let end_before_footer = cursor.start() + excerpt.text_summary.len;
1946            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1947            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1948            excerpt.buffer.reversed_chunks_in_range(start..end)
1949        });
1950        iter::from_fn(move || {
1951            if offset == *cursor.start() {
1952                cursor.prev(&());
1953                let excerpt = cursor.item()?;
1954                excerpt_chunks = Some(
1955                    excerpt
1956                        .buffer
1957                        .reversed_chunks_in_range(excerpt.range.context.clone()),
1958                );
1959            }
1960
1961            let excerpt = cursor.item().unwrap();
1962            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1963                offset -= 1;
1964                Some("\n")
1965            } else {
1966                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1967                offset -= chunk.len();
1968                Some(chunk)
1969            }
1970        })
1971        .flat_map(|c| c.chars().rev())
1972    }
1973
1974    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1975        let offset = position.to_offset(self);
1976        self.text_for_range(offset..self.len())
1977            .flat_map(|chunk| chunk.chars())
1978    }
1979
1980    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
1981        self.chunks(range, false).map(|chunk| chunk.text)
1982    }
1983
1984    pub fn is_line_blank(&self, row: u32) -> bool {
1985        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1986            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1987    }
1988
1989    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1990    where
1991        T: ToOffset,
1992    {
1993        let position = position.to_offset(self);
1994        position == self.clip_offset(position, Bias::Left)
1995            && self
1996                .bytes_in_range(position..self.len())
1997                .flatten()
1998                .copied()
1999                .take(needle.len())
2000                .eq(needle.bytes())
2001    }
2002
2003    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
2004        let mut start = start.to_offset(self);
2005        let mut end = start;
2006        let mut next_chars = self.chars_at(start).peekable();
2007        let mut prev_chars = self.reversed_chars_at(start).peekable();
2008
2009        let scope = self.language_scope_at(start);
2010        let kind = |c| char_kind(&scope, c);
2011        let word_kind = cmp::max(
2012            prev_chars.peek().copied().map(kind),
2013            next_chars.peek().copied().map(kind),
2014        );
2015
2016        for ch in prev_chars {
2017            if Some(kind(ch)) == word_kind && ch != '\n' {
2018                start -= ch.len_utf8();
2019            } else {
2020                break;
2021            }
2022        }
2023
2024        for ch in next_chars {
2025            if Some(kind(ch)) == word_kind && ch != '\n' {
2026                end += ch.len_utf8();
2027            } else {
2028                break;
2029            }
2030        }
2031
2032        (start..end, word_kind)
2033    }
2034
2035    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
2036        if self.singleton {
2037            self.excerpts
2038                .iter()
2039                .next()
2040                .map(|e| (&e.id, e.buffer_id, &e.buffer))
2041        } else {
2042            None
2043        }
2044    }
2045
2046    pub fn len(&self) -> usize {
2047        self.excerpts.summary().text.len
2048    }
2049
2050    pub fn is_empty(&self) -> bool {
2051        self.excerpts.summary().text.len == 0
2052    }
2053
2054    pub fn max_buffer_row(&self) -> u32 {
2055        self.excerpts.summary().max_buffer_row
2056    }
2057
2058    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2059        if let Some((_, _, buffer)) = self.as_singleton() {
2060            return buffer.clip_offset(offset, bias);
2061        }
2062
2063        let mut cursor = self.excerpts.cursor::<usize>();
2064        cursor.seek(&offset, Bias::Right, &());
2065        let overshoot = if let Some(excerpt) = cursor.item() {
2066            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2067            let buffer_offset = excerpt
2068                .buffer
2069                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
2070            buffer_offset.saturating_sub(excerpt_start)
2071        } else {
2072            0
2073        };
2074        cursor.start() + overshoot
2075    }
2076
2077    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2078        if let Some((_, _, buffer)) = self.as_singleton() {
2079            return buffer.clip_point(point, bias);
2080        }
2081
2082        let mut cursor = self.excerpts.cursor::<Point>();
2083        cursor.seek(&point, Bias::Right, &());
2084        let overshoot = if let Some(excerpt) = cursor.item() {
2085            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2086            let buffer_point = excerpt
2087                .buffer
2088                .clip_point(excerpt_start + (point - cursor.start()), bias);
2089            buffer_point.saturating_sub(excerpt_start)
2090        } else {
2091            Point::zero()
2092        };
2093        *cursor.start() + overshoot
2094    }
2095
2096    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2097        if let Some((_, _, buffer)) = self.as_singleton() {
2098            return buffer.clip_offset_utf16(offset, bias);
2099        }
2100
2101        let mut cursor = self.excerpts.cursor::<OffsetUtf16>();
2102        cursor.seek(&offset, Bias::Right, &());
2103        let overshoot = if let Some(excerpt) = cursor.item() {
2104            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2105            let buffer_offset = excerpt
2106                .buffer
2107                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
2108            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
2109        } else {
2110            OffsetUtf16(0)
2111        };
2112        *cursor.start() + overshoot
2113    }
2114
2115    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2116        if let Some((_, _, buffer)) = self.as_singleton() {
2117            return buffer.clip_point_utf16(point, bias);
2118        }
2119
2120        let mut cursor = self.excerpts.cursor::<PointUtf16>();
2121        cursor.seek(&point.0, Bias::Right, &());
2122        let overshoot = if let Some(excerpt) = cursor.item() {
2123            let excerpt_start = excerpt
2124                .buffer
2125                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2126            let buffer_point = excerpt
2127                .buffer
2128                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
2129            buffer_point.saturating_sub(excerpt_start)
2130        } else {
2131            PointUtf16::zero()
2132        };
2133        *cursor.start() + overshoot
2134    }
2135
2136    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
2137        let range = range.start.to_offset(self)..range.end.to_offset(self);
2138        let mut excerpts = self.excerpts.cursor::<usize>();
2139        excerpts.seek(&range.start, Bias::Right, &());
2140
2141        let mut chunk = &[][..];
2142        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2143            let mut excerpt_bytes = excerpt
2144                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
2145            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2146            Some(excerpt_bytes)
2147        } else {
2148            None
2149        };
2150        MultiBufferBytes {
2151            range,
2152            excerpts,
2153            excerpt_bytes,
2154            chunk,
2155        }
2156    }
2157
2158    pub fn reversed_bytes_in_range<T: ToOffset>(
2159        &self,
2160        range: Range<T>,
2161    ) -> ReversedMultiBufferBytes {
2162        let range = range.start.to_offset(self)..range.end.to_offset(self);
2163        let mut excerpts = self.excerpts.cursor::<usize>();
2164        excerpts.seek(&range.end, Bias::Left, &());
2165
2166        let mut chunk = &[][..];
2167        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2168            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
2169                range.start - excerpts.start()..range.end - excerpts.start(),
2170            );
2171            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2172            Some(excerpt_bytes)
2173        } else {
2174            None
2175        };
2176
2177        ReversedMultiBufferBytes {
2178            range,
2179            excerpts,
2180            excerpt_bytes,
2181            chunk,
2182        }
2183    }
2184
2185    pub fn buffer_rows(&self, start_row: u32) -> MultiBufferRows {
2186        let mut result = MultiBufferRows {
2187            buffer_row_range: 0..0,
2188            excerpts: self.excerpts.cursor(),
2189        };
2190        result.seek(start_row);
2191        result
2192    }
2193
2194    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
2195        let range = range.start.to_offset(self)..range.end.to_offset(self);
2196        let mut chunks = MultiBufferChunks {
2197            range: range.clone(),
2198            excerpts: self.excerpts.cursor(),
2199            excerpt_chunks: None,
2200            language_aware,
2201        };
2202        chunks.seek(range.start);
2203        chunks
2204    }
2205
2206    pub fn offset_to_point(&self, offset: usize) -> Point {
2207        if let Some((_, _, buffer)) = self.as_singleton() {
2208            return buffer.offset_to_point(offset);
2209        }
2210
2211        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2212        cursor.seek(&offset, Bias::Right, &());
2213        if let Some(excerpt) = cursor.item() {
2214            let (start_offset, start_point) = cursor.start();
2215            let overshoot = offset - start_offset;
2216            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2217            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2218            let buffer_point = excerpt
2219                .buffer
2220                .offset_to_point(excerpt_start_offset + overshoot);
2221            *start_point + (buffer_point - excerpt_start_point)
2222        } else {
2223            self.excerpts.summary().text.lines
2224        }
2225    }
2226
2227    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2228        if let Some((_, _, buffer)) = self.as_singleton() {
2229            return buffer.offset_to_point_utf16(offset);
2230        }
2231
2232        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
2233        cursor.seek(&offset, Bias::Right, &());
2234        if let Some(excerpt) = cursor.item() {
2235            let (start_offset, start_point) = cursor.start();
2236            let overshoot = offset - start_offset;
2237            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2238            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2239            let buffer_point = excerpt
2240                .buffer
2241                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2242            *start_point + (buffer_point - excerpt_start_point)
2243        } else {
2244            self.excerpts.summary().text.lines_utf16()
2245        }
2246    }
2247
2248    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2249        if let Some((_, _, buffer)) = self.as_singleton() {
2250            return buffer.point_to_point_utf16(point);
2251        }
2252
2253        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
2254        cursor.seek(&point, Bias::Right, &());
2255        if let Some(excerpt) = cursor.item() {
2256            let (start_offset, start_point) = cursor.start();
2257            let overshoot = point - start_offset;
2258            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2259            let excerpt_start_point_utf16 =
2260                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2261            let buffer_point = excerpt
2262                .buffer
2263                .point_to_point_utf16(excerpt_start_point + overshoot);
2264            *start_point + (buffer_point - excerpt_start_point_utf16)
2265        } else {
2266            self.excerpts.summary().text.lines_utf16()
2267        }
2268    }
2269
2270    pub fn point_to_offset(&self, point: Point) -> usize {
2271        if let Some((_, _, buffer)) = self.as_singleton() {
2272            return buffer.point_to_offset(point);
2273        }
2274
2275        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
2276        cursor.seek(&point, Bias::Right, &());
2277        if let Some(excerpt) = cursor.item() {
2278            let (start_point, start_offset) = cursor.start();
2279            let overshoot = point - start_point;
2280            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2281            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2282            let buffer_offset = excerpt
2283                .buffer
2284                .point_to_offset(excerpt_start_point + overshoot);
2285            *start_offset + buffer_offset - excerpt_start_offset
2286        } else {
2287            self.excerpts.summary().text.len
2288        }
2289    }
2290
2291    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2292        if let Some((_, _, buffer)) = self.as_singleton() {
2293            return buffer.offset_utf16_to_offset(offset_utf16);
2294        }
2295
2296        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>();
2297        cursor.seek(&offset_utf16, Bias::Right, &());
2298        if let Some(excerpt) = cursor.item() {
2299            let (start_offset_utf16, start_offset) = cursor.start();
2300            let overshoot = offset_utf16 - start_offset_utf16;
2301            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2302            let excerpt_start_offset_utf16 =
2303                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2304            let buffer_offset = excerpt
2305                .buffer
2306                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2307            *start_offset + (buffer_offset - excerpt_start_offset)
2308        } else {
2309            self.excerpts.summary().text.len
2310        }
2311    }
2312
2313    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2314        if let Some((_, _, buffer)) = self.as_singleton() {
2315            return buffer.offset_to_offset_utf16(offset);
2316        }
2317
2318        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>();
2319        cursor.seek(&offset, Bias::Right, &());
2320        if let Some(excerpt) = cursor.item() {
2321            let (start_offset, start_offset_utf16) = cursor.start();
2322            let overshoot = offset - start_offset;
2323            let excerpt_start_offset_utf16 =
2324                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2325            let excerpt_start_offset = excerpt
2326                .buffer
2327                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2328            let buffer_offset_utf16 = excerpt
2329                .buffer
2330                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2331            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2332        } else {
2333            self.excerpts.summary().text.len_utf16
2334        }
2335    }
2336
2337    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2338        if let Some((_, _, buffer)) = self.as_singleton() {
2339            return buffer.point_utf16_to_offset(point);
2340        }
2341
2342        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
2343        cursor.seek(&point, Bias::Right, &());
2344        if let Some(excerpt) = cursor.item() {
2345            let (start_point, start_offset) = cursor.start();
2346            let overshoot = point - start_point;
2347            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2348            let excerpt_start_point = excerpt
2349                .buffer
2350                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2351            let buffer_offset = excerpt
2352                .buffer
2353                .point_utf16_to_offset(excerpt_start_point + overshoot);
2354            *start_offset + (buffer_offset - excerpt_start_offset)
2355        } else {
2356            self.excerpts.summary().text.len
2357        }
2358    }
2359
2360    pub fn point_to_buffer_offset<T: ToOffset>(
2361        &self,
2362        point: T,
2363    ) -> Option<(&BufferSnapshot, usize)> {
2364        let offset = point.to_offset(self);
2365        let mut cursor = self.excerpts.cursor::<usize>();
2366        cursor.seek(&offset, Bias::Right, &());
2367        if cursor.item().is_none() {
2368            cursor.prev(&());
2369        }
2370
2371        cursor.item().map(|excerpt| {
2372            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2373            let buffer_point = excerpt_start + offset - *cursor.start();
2374            (&excerpt.buffer, buffer_point)
2375        })
2376    }
2377
2378    pub fn suggested_indents(
2379        &self,
2380        rows: impl IntoIterator<Item = u32>,
2381        cx: &AppContext,
2382    ) -> BTreeMap<u32, IndentSize> {
2383        let mut result = BTreeMap::new();
2384
2385        let mut rows_for_excerpt = Vec::new();
2386        let mut cursor = self.excerpts.cursor::<Point>();
2387        let mut rows = rows.into_iter().peekable();
2388        let mut prev_row = u32::MAX;
2389        let mut prev_language_indent_size = IndentSize::default();
2390
2391        while let Some(row) = rows.next() {
2392            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2393            let excerpt = match cursor.item() {
2394                Some(excerpt) => excerpt,
2395                _ => continue,
2396            };
2397
2398            // Retrieve the language and indent size once for each disjoint region being indented.
2399            let single_indent_size = if row.saturating_sub(1) == prev_row {
2400                prev_language_indent_size
2401            } else {
2402                excerpt
2403                    .buffer
2404                    .language_indent_size_at(Point::new(row, 0), cx)
2405            };
2406            prev_language_indent_size = single_indent_size;
2407            prev_row = row;
2408
2409            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2410            let start_multibuffer_row = cursor.start().row;
2411
2412            rows_for_excerpt.push(row);
2413            while let Some(next_row) = rows.peek().copied() {
2414                if cursor.end(&()).row > next_row {
2415                    rows_for_excerpt.push(next_row);
2416                    rows.next();
2417                } else {
2418                    break;
2419                }
2420            }
2421
2422            let buffer_rows = rows_for_excerpt
2423                .drain(..)
2424                .map(|row| start_buffer_row + row - start_multibuffer_row);
2425            let buffer_indents = excerpt
2426                .buffer
2427                .suggested_indents(buffer_rows, single_indent_size);
2428            let multibuffer_indents = buffer_indents
2429                .into_iter()
2430                .map(|(row, indent)| (start_multibuffer_row + row - start_buffer_row, indent));
2431            result.extend(multibuffer_indents);
2432        }
2433
2434        result
2435    }
2436
2437    pub fn indent_size_for_line(&self, row: u32) -> IndentSize {
2438        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2439            let mut size = buffer.indent_size_for_line(range.start.row);
2440            size.len = size
2441                .len
2442                .min(range.end.column)
2443                .saturating_sub(range.start.column);
2444            size
2445        } else {
2446            IndentSize::spaces(0)
2447        }
2448    }
2449
2450    pub fn prev_non_blank_row(&self, mut row: u32) -> Option<u32> {
2451        while row > 0 {
2452            row -= 1;
2453            if !self.is_line_blank(row) {
2454                return Some(row);
2455            }
2456        }
2457        None
2458    }
2459
2460    pub fn line_len(&self, row: u32) -> u32 {
2461        if let Some((_, range)) = self.buffer_line_for_row(row) {
2462            range.end.column - range.start.column
2463        } else {
2464            0
2465        }
2466    }
2467
2468    pub fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
2469        let mut cursor = self.excerpts.cursor::<Point>();
2470        let point = Point::new(row, 0);
2471        cursor.seek(&point, Bias::Right, &());
2472        if cursor.item().is_none() && *cursor.start() == point {
2473            cursor.prev(&());
2474        }
2475        if let Some(excerpt) = cursor.item() {
2476            let overshoot = row - cursor.start().row;
2477            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2478            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2479            let buffer_row = excerpt_start.row + overshoot;
2480            let line_start = Point::new(buffer_row, 0);
2481            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2482            return Some((
2483                &excerpt.buffer,
2484                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2485            ));
2486        }
2487        None
2488    }
2489
2490    pub fn max_point(&self) -> Point {
2491        self.text_summary().lines
2492    }
2493
2494    pub fn text_summary(&self) -> TextSummary {
2495        self.excerpts.summary().text.clone()
2496    }
2497
2498    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2499    where
2500        D: TextDimension,
2501        O: ToOffset,
2502    {
2503        let mut summary = D::default();
2504        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2505        let mut cursor = self.excerpts.cursor::<usize>();
2506        cursor.seek(&range.start, Bias::Right, &());
2507        if let Some(excerpt) = cursor.item() {
2508            let mut end_before_newline = cursor.end(&());
2509            if excerpt.has_trailing_newline {
2510                end_before_newline -= 1;
2511            }
2512
2513            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2514            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2515            let end_in_excerpt =
2516                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2517            summary.add_assign(
2518                &excerpt
2519                    .buffer
2520                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2521            );
2522
2523            if range.end > end_before_newline {
2524                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2525            }
2526
2527            cursor.next(&());
2528        }
2529
2530        if range.end > *cursor.start() {
2531            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2532                &range.end,
2533                Bias::Right,
2534                &(),
2535            )));
2536            if let Some(excerpt) = cursor.item() {
2537                range.end = cmp::max(*cursor.start(), range.end);
2538
2539                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2540                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2541                summary.add_assign(
2542                    &excerpt
2543                        .buffer
2544                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2545                );
2546            }
2547        }
2548
2549        summary
2550    }
2551
2552    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2553    where
2554        D: TextDimension + Ord + Sub<D, Output = D>,
2555    {
2556        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2557        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
2558
2559        cursor.seek(locator, Bias::Left, &());
2560        if cursor.item().is_none() {
2561            cursor.next(&());
2562        }
2563
2564        let mut position = D::from_text_summary(&cursor.start().text);
2565        if let Some(excerpt) = cursor.item() {
2566            if excerpt.id == anchor.excerpt_id {
2567                let excerpt_buffer_start =
2568                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2569                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2570                let buffer_position = cmp::min(
2571                    excerpt_buffer_end,
2572                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
2573                );
2574                if buffer_position > excerpt_buffer_start {
2575                    position.add_assign(&(buffer_position - excerpt_buffer_start));
2576                }
2577            }
2578        }
2579        position
2580    }
2581
2582    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
2583    where
2584        D: TextDimension + Ord + Sub<D, Output = D>,
2585        I: 'a + IntoIterator<Item = &'a Anchor>,
2586    {
2587        if let Some((_, _, buffer)) = self.as_singleton() {
2588            return buffer
2589                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
2590                .collect();
2591        }
2592
2593        let mut anchors = anchors.into_iter().peekable();
2594        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2595        let mut summaries = Vec::new();
2596        while let Some(anchor) = anchors.peek() {
2597            let excerpt_id = anchor.excerpt_id;
2598            let excerpt_anchors = iter::from_fn(|| {
2599                let anchor = anchors.peek()?;
2600                if anchor.excerpt_id == excerpt_id {
2601                    Some(&anchors.next().unwrap().text_anchor)
2602                } else {
2603                    None
2604                }
2605            });
2606
2607            let locator = self.excerpt_locator_for_id(excerpt_id);
2608            cursor.seek_forward(locator, Bias::Left, &());
2609            if cursor.item().is_none() {
2610                cursor.next(&());
2611            }
2612
2613            let position = D::from_text_summary(&cursor.start().text);
2614            if let Some(excerpt) = cursor.item() {
2615                if excerpt.id == excerpt_id {
2616                    let excerpt_buffer_start =
2617                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2618                    let excerpt_buffer_end =
2619                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2620                    summaries.extend(
2621                        excerpt
2622                            .buffer
2623                            .summaries_for_anchors::<D, _>(excerpt_anchors)
2624                            .map(move |summary| {
2625                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
2626                                let mut position = position.clone();
2627                                let excerpt_buffer_start = excerpt_buffer_start.clone();
2628                                if summary > excerpt_buffer_start {
2629                                    position.add_assign(&(summary - excerpt_buffer_start));
2630                                }
2631                                position
2632                            }),
2633                    );
2634                    continue;
2635                }
2636            }
2637
2638            summaries.extend(excerpt_anchors.map(|_| position.clone()));
2639        }
2640
2641        summaries
2642    }
2643
2644    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
2645    where
2646        I: 'a + IntoIterator<Item = &'a Anchor>,
2647    {
2648        let mut anchors = anchors.into_iter().enumerate().peekable();
2649        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2650        cursor.next(&());
2651
2652        let mut result = Vec::new();
2653
2654        while let Some((_, anchor)) = anchors.peek() {
2655            let old_excerpt_id = anchor.excerpt_id;
2656
2657            // Find the location where this anchor's excerpt should be.
2658            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
2659            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
2660
2661            if cursor.item().is_none() {
2662                cursor.next(&());
2663            }
2664
2665            let next_excerpt = cursor.item();
2666            let prev_excerpt = cursor.prev_item();
2667
2668            // Process all of the anchors for this excerpt.
2669            while let Some((_, anchor)) = anchors.peek() {
2670                if anchor.excerpt_id != old_excerpt_id {
2671                    break;
2672                }
2673                let (anchor_ix, anchor) = anchors.next().unwrap();
2674                let mut anchor = *anchor;
2675
2676                // Leave min and max anchors unchanged if invalid or
2677                // if the old excerpt still exists at this location
2678                let mut kept_position = next_excerpt
2679                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
2680                    || old_excerpt_id == ExcerptId::max()
2681                    || old_excerpt_id == ExcerptId::min();
2682
2683                // If the old excerpt no longer exists at this location, then attempt to
2684                // find an equivalent position for this anchor in an adjacent excerpt.
2685                if !kept_position {
2686                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
2687                        if excerpt.contains(&anchor) {
2688                            anchor.excerpt_id = excerpt.id;
2689                            kept_position = true;
2690                            break;
2691                        }
2692                    }
2693                }
2694
2695                // If there's no adjacent excerpt that contains the anchor's position,
2696                // then report that the anchor has lost its position.
2697                if !kept_position {
2698                    anchor = if let Some(excerpt) = next_excerpt {
2699                        let mut text_anchor = excerpt
2700                            .range
2701                            .context
2702                            .start
2703                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2704                        if text_anchor
2705                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
2706                            .is_gt()
2707                        {
2708                            text_anchor = excerpt.range.context.end;
2709                        }
2710                        Anchor {
2711                            buffer_id: Some(excerpt.buffer_id),
2712                            excerpt_id: excerpt.id,
2713                            text_anchor,
2714                        }
2715                    } else if let Some(excerpt) = prev_excerpt {
2716                        let mut text_anchor = excerpt
2717                            .range
2718                            .context
2719                            .end
2720                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2721                        if text_anchor
2722                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
2723                            .is_lt()
2724                        {
2725                            text_anchor = excerpt.range.context.start;
2726                        }
2727                        Anchor {
2728                            buffer_id: Some(excerpt.buffer_id),
2729                            excerpt_id: excerpt.id,
2730                            text_anchor,
2731                        }
2732                    } else if anchor.text_anchor.bias == Bias::Left {
2733                        Anchor::min()
2734                    } else {
2735                        Anchor::max()
2736                    };
2737                }
2738
2739                result.push((anchor_ix, anchor, kept_position));
2740            }
2741        }
2742        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
2743        result
2744    }
2745
2746    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2747        self.anchor_at(position, Bias::Left)
2748    }
2749
2750    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2751        self.anchor_at(position, Bias::Right)
2752    }
2753
2754    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
2755        let offset = position.to_offset(self);
2756        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
2757            return Anchor {
2758                buffer_id: Some(buffer_id),
2759                excerpt_id: *excerpt_id,
2760                text_anchor: buffer.anchor_at(offset, bias),
2761            };
2762        }
2763
2764        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>();
2765        cursor.seek(&offset, Bias::Right, &());
2766        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
2767            cursor.prev(&());
2768        }
2769        if let Some(excerpt) = cursor.item() {
2770            let mut overshoot = offset.saturating_sub(cursor.start().0);
2771            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
2772                overshoot -= 1;
2773                bias = Bias::Right;
2774            }
2775
2776            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2777            let text_anchor =
2778                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
2779            Anchor {
2780                buffer_id: Some(excerpt.buffer_id),
2781                excerpt_id: excerpt.id,
2782                text_anchor,
2783            }
2784        } else if offset == 0 && bias == Bias::Left {
2785            Anchor::min()
2786        } else {
2787            Anchor::max()
2788        }
2789    }
2790
2791    /// Returns an anchor for the given excerpt and text anchor,
2792    /// returns None if the excerpt_id is no longer valid.
2793    pub fn anchor_in_excerpt(
2794        &self,
2795        excerpt_id: ExcerptId,
2796        text_anchor: text::Anchor,
2797    ) -> Option<Anchor> {
2798        let locator = self.excerpt_locator_for_id(excerpt_id);
2799        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2800        cursor.seek(locator, Bias::Left, &());
2801        if let Some(excerpt) = cursor.item() {
2802            if excerpt.id == excerpt_id {
2803                let text_anchor = excerpt.clip_anchor(text_anchor);
2804                drop(cursor);
2805                return Some(Anchor {
2806                    buffer_id: Some(excerpt.buffer_id),
2807                    excerpt_id,
2808                    text_anchor,
2809                });
2810            }
2811        }
2812        None
2813    }
2814
2815    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2816        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
2817            true
2818        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
2819            excerpt.buffer.can_resolve(&anchor.text_anchor)
2820        } else {
2821            false
2822        }
2823    }
2824
2825    pub fn excerpts(
2826        &self,
2827    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
2828        self.excerpts
2829            .iter()
2830            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
2831    }
2832
2833    fn excerpts_for_range<T: ToOffset>(
2834        &self,
2835        range: Range<T>,
2836    ) -> impl Iterator<Item = (&Excerpt, usize)> + '_ {
2837        let range = range.start.to_offset(self)..range.end.to_offset(self);
2838
2839        let mut cursor = self.excerpts.cursor::<usize>();
2840        cursor.seek(&range.start, Bias::Right, &());
2841        cursor.prev(&());
2842
2843        iter::from_fn(move || {
2844            cursor.next(&());
2845            if cursor.start() < &range.end {
2846                cursor.item().map(|item| (item, *cursor.start()))
2847            } else {
2848                None
2849            }
2850        })
2851    }
2852
2853    pub fn excerpt_boundaries_in_range<R, T>(
2854        &self,
2855        range: R,
2856    ) -> impl Iterator<Item = ExcerptBoundary> + '_
2857    where
2858        R: RangeBounds<T>,
2859        T: ToOffset,
2860    {
2861        let start_offset;
2862        let start = match range.start_bound() {
2863            Bound::Included(start) => {
2864                start_offset = start.to_offset(self);
2865                Bound::Included(start_offset)
2866            }
2867            Bound::Excluded(start) => {
2868                start_offset = start.to_offset(self);
2869                Bound::Excluded(start_offset)
2870            }
2871            Bound::Unbounded => {
2872                start_offset = 0;
2873                Bound::Unbounded
2874            }
2875        };
2876        let end = match range.end_bound() {
2877            Bound::Included(end) => Bound::Included(end.to_offset(self)),
2878            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
2879            Bound::Unbounded => Bound::Unbounded,
2880        };
2881        let bounds = (start, end);
2882
2883        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2884        cursor.seek(&start_offset, Bias::Right, &());
2885        if cursor.item().is_none() {
2886            cursor.prev(&());
2887        }
2888        if !bounds.contains(&cursor.start().0) {
2889            cursor.next(&());
2890        }
2891
2892        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
2893        std::iter::from_fn(move || {
2894            if self.singleton {
2895                None
2896            } else if bounds.contains(&cursor.start().0) {
2897                let excerpt = cursor.item()?;
2898                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
2899                let boundary = ExcerptBoundary {
2900                    id: excerpt.id,
2901                    row: cursor.start().1.row,
2902                    buffer: excerpt.buffer.clone(),
2903                    range: excerpt.range.clone(),
2904                    starts_new_buffer,
2905                };
2906
2907                prev_buffer_id = Some(excerpt.buffer_id);
2908                cursor.next(&());
2909                Some(boundary)
2910            } else {
2911                None
2912            }
2913        })
2914    }
2915
2916    pub fn edit_count(&self) -> usize {
2917        self.edit_count
2918    }
2919
2920    pub fn parse_count(&self) -> usize {
2921        self.parse_count
2922    }
2923
2924    /// Returns the smallest enclosing bracket ranges containing the given range or
2925    /// None if no brackets contain range or the range is not contained in a single
2926    /// excerpt
2927    ///
2928    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
2929    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
2930        &self,
2931        range: Range<T>,
2932        range_filter: Option<&dyn Fn(Range<usize>, Range<usize>) -> bool>,
2933    ) -> Option<(Range<usize>, Range<usize>)> {
2934        let range = range.start.to_offset(self)..range.end.to_offset(self);
2935        let excerpt = self.excerpt_containing(range.clone())?;
2936
2937        // Filter to ranges contained in the excerpt
2938        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
2939            excerpt.contains_buffer_range(open.start..close.end)
2940                && range_filter.map_or(true, |filter| {
2941                    filter(
2942                        excerpt.map_range_from_buffer(open),
2943                        excerpt.map_range_from_buffer(close),
2944                    )
2945                })
2946        };
2947
2948        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
2949            excerpt.map_range_to_buffer(range),
2950            Some(&range_filter),
2951        )?;
2952
2953        Some((
2954            excerpt.map_range_from_buffer(open),
2955            excerpt.map_range_from_buffer(close),
2956        ))
2957    }
2958
2959    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
2960    /// not contained in a single excerpt
2961    pub fn enclosing_bracket_ranges<T: ToOffset>(
2962        &self,
2963        range: Range<T>,
2964    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
2965        let range = range.start.to_offset(self)..range.end.to_offset(self);
2966        let excerpt = self.excerpt_containing(range.clone())?;
2967
2968        Some(
2969            excerpt
2970                .buffer()
2971                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
2972                .filter_map(move |(open, close)| {
2973                    if excerpt.contains_buffer_range(open.start..close.end) {
2974                        Some((
2975                            excerpt.map_range_from_buffer(open),
2976                            excerpt.map_range_from_buffer(close),
2977                        ))
2978                    } else {
2979                        None
2980                    }
2981                }),
2982        )
2983    }
2984
2985    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
2986    /// not contained in a single excerpt
2987    pub fn bracket_ranges<T: ToOffset>(
2988        &self,
2989        range: Range<T>,
2990    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
2991        let range = range.start.to_offset(self)..range.end.to_offset(self);
2992        let excerpt = self.excerpt_containing(range.clone())?;
2993
2994        Some(
2995            excerpt
2996                .buffer()
2997                .bracket_ranges(excerpt.map_range_to_buffer(range))
2998                .filter_map(move |(start_bracket_range, close_bracket_range)| {
2999                    let buffer_range = start_bracket_range.start..close_bracket_range.end;
3000                    if excerpt.contains_buffer_range(buffer_range) {
3001                        Some((
3002                            excerpt.map_range_from_buffer(start_bracket_range),
3003                            excerpt.map_range_from_buffer(close_bracket_range),
3004                        ))
3005                    } else {
3006                        None
3007                    }
3008                }),
3009        )
3010    }
3011
3012    pub fn redacted_ranges<'a, T: ToOffset>(
3013        &'a self,
3014        range: Range<T>,
3015        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
3016    ) -> impl Iterator<Item = Range<usize>> + 'a {
3017        let range = range.start.to_offset(self)..range.end.to_offset(self);
3018        self.excerpts_for_range(range.clone())
3019            .filter_map(move |(excerpt, excerpt_offset)| {
3020                redaction_enabled(excerpt.buffer.file()).then(move || {
3021                    let excerpt_buffer_start =
3022                        excerpt.range.context.start.to_offset(&excerpt.buffer);
3023
3024                    excerpt
3025                        .buffer
3026                        .redacted_ranges(excerpt.range.context.clone())
3027                        .map(move |mut redacted_range| {
3028                            // Re-base onto the excerpts coordinates in the multibuffer
3029                            redacted_range.start =
3030                                excerpt_offset + (redacted_range.start - excerpt_buffer_start);
3031                            redacted_range.end =
3032                                excerpt_offset + (redacted_range.end - excerpt_buffer_start);
3033
3034                            redacted_range
3035                        })
3036                        .skip_while(move |redacted_range| redacted_range.end < range.start)
3037                        .take_while(move |redacted_range| redacted_range.start < range.end)
3038                })
3039            })
3040            .flatten()
3041    }
3042
3043    pub fn diagnostics_update_count(&self) -> usize {
3044        self.diagnostics_update_count
3045    }
3046
3047    pub fn git_diff_update_count(&self) -> usize {
3048        self.git_diff_update_count
3049    }
3050
3051    pub fn trailing_excerpt_update_count(&self) -> usize {
3052        self.trailing_excerpt_update_count
3053    }
3054
3055    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
3056        self.point_to_buffer_offset(point)
3057            .and_then(|(buffer, _)| buffer.file())
3058    }
3059
3060    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
3061        self.point_to_buffer_offset(point)
3062            .and_then(|(buffer, offset)| buffer.language_at(offset))
3063    }
3064
3065    pub fn settings_at<'a, T: ToOffset>(
3066        &'a self,
3067        point: T,
3068        cx: &'a AppContext,
3069    ) -> &'a LanguageSettings {
3070        let mut language = None;
3071        let mut file = None;
3072        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
3073            language = buffer.language_at(offset);
3074            file = buffer.file();
3075        }
3076        language_settings(language, file, cx)
3077    }
3078
3079    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
3080        self.point_to_buffer_offset(point)
3081            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
3082    }
3083
3084    pub fn language_indent_size_at<T: ToOffset>(
3085        &self,
3086        position: T,
3087        cx: &AppContext,
3088    ) -> Option<IndentSize> {
3089        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
3090        Some(buffer_snapshot.language_indent_size_at(offset, cx))
3091    }
3092
3093    pub fn is_dirty(&self) -> bool {
3094        self.is_dirty
3095    }
3096
3097    pub fn has_conflict(&self) -> bool {
3098        self.has_conflict
3099    }
3100
3101    pub fn has_diagnostics(&self) -> bool {
3102        self.excerpts
3103            .iter()
3104            .any(|excerpt| excerpt.buffer.has_diagnostics())
3105    }
3106
3107    pub fn diagnostic_group<'a, O>(
3108        &'a self,
3109        group_id: usize,
3110    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3111    where
3112        O: text::FromAnchor + 'a,
3113    {
3114        self.as_singleton()
3115            .into_iter()
3116            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
3117    }
3118
3119    pub fn diagnostics_in_range<'a, T, O>(
3120        &'a self,
3121        range: Range<T>,
3122        reversed: bool,
3123    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3124    where
3125        T: 'a + ToOffset,
3126        O: 'a + text::FromAnchor + Ord,
3127    {
3128        self.as_singleton()
3129            .into_iter()
3130            .flat_map(move |(_, _, buffer)| {
3131                buffer.diagnostics_in_range(
3132                    range.start.to_offset(self)..range.end.to_offset(self),
3133                    reversed,
3134                )
3135            })
3136    }
3137
3138    pub fn has_git_diffs(&self) -> bool {
3139        for excerpt in self.excerpts.iter() {
3140            if excerpt.buffer.has_git_diff() {
3141                return true;
3142            }
3143        }
3144        false
3145    }
3146
3147    pub fn git_diff_hunks_in_range_rev(
3148        &self,
3149        row_range: Range<u32>,
3150    ) -> impl Iterator<Item = DiffHunk<u32>> + '_ {
3151        let mut cursor = self.excerpts.cursor::<Point>();
3152
3153        cursor.seek(&Point::new(row_range.end, 0), Bias::Left, &());
3154        if cursor.item().is_none() {
3155            cursor.prev(&());
3156        }
3157
3158        std::iter::from_fn(move || {
3159            let excerpt = cursor.item()?;
3160            let multibuffer_start = *cursor.start();
3161            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3162            if multibuffer_start.row >= row_range.end {
3163                return None;
3164            }
3165
3166            let mut buffer_start = excerpt.range.context.start;
3167            let mut buffer_end = excerpt.range.context.end;
3168            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3169            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3170
3171            if row_range.start > multibuffer_start.row {
3172                let buffer_start_point =
3173                    excerpt_start_point + Point::new(row_range.start - multibuffer_start.row, 0);
3174                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3175            }
3176
3177            if row_range.end < multibuffer_end.row {
3178                let buffer_end_point =
3179                    excerpt_start_point + Point::new(row_range.end - multibuffer_start.row, 0);
3180                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3181            }
3182
3183            let buffer_hunks = excerpt
3184                .buffer
3185                .git_diff_hunks_intersecting_range_rev(buffer_start..buffer_end)
3186                .map(move |hunk| {
3187                    let start = multibuffer_start.row
3188                        + hunk
3189                            .associated_range
3190                            .start
3191                            .saturating_sub(excerpt_start_point.row);
3192                    let end = multibuffer_start.row
3193                        + hunk
3194                            .associated_range
3195                            .end
3196                            .min(excerpt_end_point.row + 1)
3197                            .saturating_sub(excerpt_start_point.row);
3198
3199                    DiffHunk {
3200                        associated_range: start..end,
3201                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3202                        buffer_range: hunk.buffer_range.clone(),
3203                        buffer_id: hunk.buffer_id,
3204                    }
3205                });
3206
3207            cursor.prev(&());
3208
3209            Some(buffer_hunks)
3210        })
3211        .flatten()
3212    }
3213
3214    pub fn git_diff_hunks_in_range(
3215        &self,
3216        row_range: Range<u32>,
3217    ) -> impl Iterator<Item = DiffHunk<u32>> + '_ {
3218        let mut cursor = self.excerpts.cursor::<Point>();
3219
3220        cursor.seek(&Point::new(row_range.start, 0), Bias::Left, &());
3221
3222        std::iter::from_fn(move || {
3223            let excerpt = cursor.item()?;
3224            let multibuffer_start = *cursor.start();
3225            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3226            let mut buffer_start = excerpt.range.context.start;
3227            let mut buffer_end = excerpt.range.context.end;
3228
3229            let excerpt_rows = match multibuffer_start.row.cmp(&row_range.end) {
3230                cmp::Ordering::Less => {
3231                    let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3232                    let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3233
3234                    if row_range.start > multibuffer_start.row {
3235                        let buffer_start_point = excerpt_start_point
3236                            + Point::new(row_range.start - multibuffer_start.row, 0);
3237                        buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3238                    }
3239
3240                    if row_range.end < multibuffer_end.row {
3241                        let buffer_end_point = excerpt_start_point
3242                            + Point::new(row_range.end - multibuffer_start.row, 0);
3243                        buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3244                    }
3245                    excerpt_start_point.row..excerpt_end_point.row
3246                }
3247                cmp::Ordering::Equal if row_range.end == 0 => {
3248                    buffer_end = buffer_start;
3249                    0..0
3250                }
3251                cmp::Ordering::Greater | cmp::Ordering::Equal => return None,
3252            };
3253
3254            let buffer_hunks = excerpt
3255                .buffer
3256                .git_diff_hunks_intersecting_range(buffer_start..buffer_end)
3257                .map(move |hunk| {
3258                    let buffer_range = if excerpt_rows.start == 0 && excerpt_rows.end == 0 {
3259                        0..1
3260                    } else {
3261                        let start = multibuffer_start.row
3262                            + hunk
3263                                .associated_range
3264                                .start
3265                                .saturating_sub(excerpt_rows.start);
3266                        let end = multibuffer_start.row
3267                            + hunk
3268                                .associated_range
3269                                .end
3270                                .min(excerpt_rows.end + 1)
3271                                .saturating_sub(excerpt_rows.start);
3272                        start..end
3273                    };
3274                    DiffHunk {
3275                        associated_range: buffer_range,
3276                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3277                        buffer_range: hunk.buffer_range.clone(),
3278                        buffer_id: hunk.buffer_id,
3279                    }
3280                });
3281
3282            cursor.next(&());
3283
3284            Some(buffer_hunks)
3285        })
3286        .flatten()
3287    }
3288
3289    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
3290        let range = range.start.to_offset(self)..range.end.to_offset(self);
3291        let excerpt = self.excerpt_containing(range.clone())?;
3292
3293        let ancestor_buffer_range = excerpt
3294            .buffer()
3295            .range_for_syntax_ancestor(excerpt.map_range_to_buffer(range))?;
3296
3297        Some(excerpt.map_range_from_buffer(ancestor_buffer_range))
3298    }
3299
3300    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
3301        let (excerpt_id, _, buffer) = self.as_singleton()?;
3302        let outline = buffer.outline(theme)?;
3303        Some(Outline::new(
3304            outline
3305                .items
3306                .into_iter()
3307                .flat_map(|item| {
3308                    Some(OutlineItem {
3309                        depth: item.depth,
3310                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
3311                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
3312                        text: item.text,
3313                        highlight_ranges: item.highlight_ranges,
3314                        name_ranges: item.name_ranges,
3315                    })
3316                })
3317                .collect(),
3318        ))
3319    }
3320
3321    pub fn symbols_containing<T: ToOffset>(
3322        &self,
3323        offset: T,
3324        theme: Option<&SyntaxTheme>,
3325    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
3326        let anchor = self.anchor_before(offset);
3327        let excerpt_id = anchor.excerpt_id;
3328        let excerpt = self.excerpt(excerpt_id)?;
3329        Some((
3330            excerpt.buffer_id,
3331            excerpt
3332                .buffer
3333                .symbols_containing(anchor.text_anchor, theme)
3334                .into_iter()
3335                .flatten()
3336                .flat_map(|item| {
3337                    Some(OutlineItem {
3338                        depth: item.depth,
3339                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
3340                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
3341                        text: item.text,
3342                        highlight_ranges: item.highlight_ranges,
3343                        name_ranges: item.name_ranges,
3344                    })
3345                })
3346                .collect(),
3347        ))
3348    }
3349
3350    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
3351        if id == ExcerptId::min() {
3352            Locator::min_ref()
3353        } else if id == ExcerptId::max() {
3354            Locator::max_ref()
3355        } else {
3356            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
3357            cursor.seek(&id, Bias::Left, &());
3358            if let Some(entry) = cursor.item() {
3359                if entry.id == id {
3360                    return &entry.locator;
3361                }
3362            }
3363            panic!("invalid excerpt id {:?}", id)
3364        }
3365    }
3366
3367    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
3368        Some(self.excerpt(excerpt_id)?.buffer_id)
3369    }
3370
3371    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
3372        Some(&self.excerpt(excerpt_id)?.buffer)
3373    }
3374
3375    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
3376        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
3377        let locator = self.excerpt_locator_for_id(excerpt_id);
3378        cursor.seek(&Some(locator), Bias::Left, &());
3379        if let Some(excerpt) = cursor.item() {
3380            if excerpt.id == excerpt_id {
3381                return Some(excerpt);
3382            }
3383        }
3384        None
3385    }
3386
3387    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
3388    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
3389        let range = range.start.to_offset(self)..range.end.to_offset(self);
3390
3391        let mut cursor = self.excerpts.cursor::<usize>();
3392        cursor.seek(&range.start, Bias::Right, &());
3393        let start_excerpt = cursor.item()?;
3394
3395        if range.start == range.end {
3396            return Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()));
3397        }
3398
3399        cursor.seek(&range.end, Bias::Right, &());
3400        let end_excerpt = cursor.item()?;
3401
3402        if start_excerpt.id != end_excerpt.id {
3403            None
3404        } else {
3405            Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()))
3406        }
3407    }
3408
3409    pub fn remote_selections_in_range<'a>(
3410        &'a self,
3411        range: &'a Range<Anchor>,
3412    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
3413        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
3414        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
3415        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
3416        cursor.seek(start_locator, Bias::Left, &());
3417        cursor
3418            .take_while(move |excerpt| excerpt.locator <= *end_locator)
3419            .flat_map(move |excerpt| {
3420                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
3421                if excerpt.id == range.start.excerpt_id {
3422                    query_range.start = range.start.text_anchor;
3423                }
3424                if excerpt.id == range.end.excerpt_id {
3425                    query_range.end = range.end.text_anchor;
3426                }
3427
3428                excerpt
3429                    .buffer
3430                    .remote_selections_in_range(query_range)
3431                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
3432                        selections.map(move |selection| {
3433                            let mut start = Anchor {
3434                                buffer_id: Some(excerpt.buffer_id),
3435                                excerpt_id: excerpt.id,
3436                                text_anchor: selection.start,
3437                            };
3438                            let mut end = Anchor {
3439                                buffer_id: Some(excerpt.buffer_id),
3440                                excerpt_id: excerpt.id,
3441                                text_anchor: selection.end,
3442                            };
3443                            if range.start.cmp(&start, self).is_gt() {
3444                                start = range.start;
3445                            }
3446                            if range.end.cmp(&end, self).is_lt() {
3447                                end = range.end;
3448                            }
3449
3450                            (
3451                                replica_id,
3452                                line_mode,
3453                                cursor_shape,
3454                                Selection {
3455                                    id: selection.id,
3456                                    start,
3457                                    end,
3458                                    reversed: selection.reversed,
3459                                    goal: selection.goal,
3460                                },
3461                            )
3462                        })
3463                    })
3464            })
3465    }
3466}
3467
3468#[cfg(any(test, feature = "test-support"))]
3469impl MultiBufferSnapshot {
3470    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
3471        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
3472        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
3473        start..end
3474    }
3475}
3476
3477impl History {
3478    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
3479        self.transaction_depth += 1;
3480        if self.transaction_depth == 1 {
3481            let id = self.next_transaction_id.tick();
3482            self.undo_stack.push(Transaction {
3483                id,
3484                buffer_transactions: Default::default(),
3485                first_edit_at: now,
3486                last_edit_at: now,
3487                suppress_grouping: false,
3488            });
3489            Some(id)
3490        } else {
3491            None
3492        }
3493    }
3494
3495    fn end_transaction(
3496        &mut self,
3497        now: Instant,
3498        buffer_transactions: HashMap<BufferId, TransactionId>,
3499    ) -> bool {
3500        assert_ne!(self.transaction_depth, 0);
3501        self.transaction_depth -= 1;
3502        if self.transaction_depth == 0 {
3503            if buffer_transactions.is_empty() {
3504                self.undo_stack.pop();
3505                false
3506            } else {
3507                self.redo_stack.clear();
3508                let transaction = self.undo_stack.last_mut().unwrap();
3509                transaction.last_edit_at = now;
3510                for (buffer_id, transaction_id) in buffer_transactions {
3511                    transaction
3512                        .buffer_transactions
3513                        .entry(buffer_id)
3514                        .or_insert(transaction_id);
3515                }
3516                true
3517            }
3518        } else {
3519            false
3520        }
3521    }
3522
3523    fn push_transaction<'a, T>(
3524        &mut self,
3525        buffer_transactions: T,
3526        now: Instant,
3527        cx: &mut ModelContext<MultiBuffer>,
3528    ) where
3529        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
3530    {
3531        assert_eq!(self.transaction_depth, 0);
3532        let transaction = Transaction {
3533            id: self.next_transaction_id.tick(),
3534            buffer_transactions: buffer_transactions
3535                .into_iter()
3536                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
3537                .collect(),
3538            first_edit_at: now,
3539            last_edit_at: now,
3540            suppress_grouping: false,
3541        };
3542        if !transaction.buffer_transactions.is_empty() {
3543            self.undo_stack.push(transaction);
3544            self.redo_stack.clear();
3545        }
3546    }
3547
3548    fn finalize_last_transaction(&mut self) {
3549        if let Some(transaction) = self.undo_stack.last_mut() {
3550            transaction.suppress_grouping = true;
3551        }
3552    }
3553
3554    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
3555        if let Some(ix) = self
3556            .undo_stack
3557            .iter()
3558            .rposition(|transaction| transaction.id == transaction_id)
3559        {
3560            Some(self.undo_stack.remove(ix))
3561        } else if let Some(ix) = self
3562            .redo_stack
3563            .iter()
3564            .rposition(|transaction| transaction.id == transaction_id)
3565        {
3566            Some(self.redo_stack.remove(ix))
3567        } else {
3568            None
3569        }
3570    }
3571
3572    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
3573        self.undo_stack
3574            .iter_mut()
3575            .find(|transaction| transaction.id == transaction_id)
3576            .or_else(|| {
3577                self.redo_stack
3578                    .iter_mut()
3579                    .find(|transaction| transaction.id == transaction_id)
3580            })
3581    }
3582
3583    fn pop_undo(&mut self) -> Option<&mut Transaction> {
3584        assert_eq!(self.transaction_depth, 0);
3585        if let Some(transaction) = self.undo_stack.pop() {
3586            self.redo_stack.push(transaction);
3587            self.redo_stack.last_mut()
3588        } else {
3589            None
3590        }
3591    }
3592
3593    fn pop_redo(&mut self) -> Option<&mut Transaction> {
3594        assert_eq!(self.transaction_depth, 0);
3595        if let Some(transaction) = self.redo_stack.pop() {
3596            self.undo_stack.push(transaction);
3597            self.undo_stack.last_mut()
3598        } else {
3599            None
3600        }
3601    }
3602
3603    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
3604        let ix = self
3605            .undo_stack
3606            .iter()
3607            .rposition(|transaction| transaction.id == transaction_id)?;
3608        let transaction = self.undo_stack.remove(ix);
3609        self.redo_stack.push(transaction);
3610        self.redo_stack.last()
3611    }
3612
3613    fn group(&mut self) -> Option<TransactionId> {
3614        let mut count = 0;
3615        let mut transactions = self.undo_stack.iter();
3616        if let Some(mut transaction) = transactions.next_back() {
3617            while let Some(prev_transaction) = transactions.next_back() {
3618                if !prev_transaction.suppress_grouping
3619                    && transaction.first_edit_at - prev_transaction.last_edit_at
3620                        <= self.group_interval
3621                {
3622                    transaction = prev_transaction;
3623                    count += 1;
3624                } else {
3625                    break;
3626                }
3627            }
3628        }
3629        self.group_trailing(count)
3630    }
3631
3632    fn group_until(&mut self, transaction_id: TransactionId) {
3633        let mut count = 0;
3634        for transaction in self.undo_stack.iter().rev() {
3635            if transaction.id == transaction_id {
3636                self.group_trailing(count);
3637                break;
3638            } else if transaction.suppress_grouping {
3639                break;
3640            } else {
3641                count += 1;
3642            }
3643        }
3644    }
3645
3646    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
3647        let new_len = self.undo_stack.len() - n;
3648        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
3649        if let Some(last_transaction) = transactions_to_keep.last_mut() {
3650            if let Some(transaction) = transactions_to_merge.last() {
3651                last_transaction.last_edit_at = transaction.last_edit_at;
3652            }
3653            for to_merge in transactions_to_merge {
3654                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
3655                    last_transaction
3656                        .buffer_transactions
3657                        .entry(*buffer_id)
3658                        .or_insert(*transaction_id);
3659                }
3660            }
3661        }
3662
3663        self.undo_stack.truncate(new_len);
3664        self.undo_stack.last().map(|t| t.id)
3665    }
3666}
3667
3668impl Excerpt {
3669    fn new(
3670        id: ExcerptId,
3671        locator: Locator,
3672        buffer_id: BufferId,
3673        buffer: BufferSnapshot,
3674        range: ExcerptRange<text::Anchor>,
3675        has_trailing_newline: bool,
3676    ) -> Self {
3677        Excerpt {
3678            id,
3679            locator,
3680            max_buffer_row: range.context.end.to_point(&buffer).row,
3681            text_summary: buffer
3682                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
3683            buffer_id,
3684            buffer,
3685            range,
3686            has_trailing_newline,
3687        }
3688    }
3689
3690    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
3691        let content_start = self.range.context.start.to_offset(&self.buffer);
3692        let chunks_start = content_start + range.start;
3693        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
3694
3695        let footer_height = if self.has_trailing_newline
3696            && range.start <= self.text_summary.len
3697            && range.end > self.text_summary.len
3698        {
3699            1
3700        } else {
3701            0
3702        };
3703
3704        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
3705
3706        ExcerptChunks {
3707            content_chunks,
3708            footer_height,
3709        }
3710    }
3711
3712    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3713        let content_start = self.range.context.start.to_offset(&self.buffer);
3714        let bytes_start = content_start + range.start;
3715        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3716        let footer_height = if self.has_trailing_newline
3717            && range.start <= self.text_summary.len
3718            && range.end > self.text_summary.len
3719        {
3720            1
3721        } else {
3722            0
3723        };
3724        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
3725
3726        ExcerptBytes {
3727            content_bytes,
3728            footer_height,
3729        }
3730    }
3731
3732    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3733        let content_start = self.range.context.start.to_offset(&self.buffer);
3734        let bytes_start = content_start + range.start;
3735        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3736        let footer_height = if self.has_trailing_newline
3737            && range.start <= self.text_summary.len
3738            && range.end > self.text_summary.len
3739        {
3740            1
3741        } else {
3742            0
3743        };
3744        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
3745
3746        ExcerptBytes {
3747            content_bytes,
3748            footer_height,
3749        }
3750    }
3751
3752    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
3753        if text_anchor
3754            .cmp(&self.range.context.start, &self.buffer)
3755            .is_lt()
3756        {
3757            self.range.context.start
3758        } else if text_anchor
3759            .cmp(&self.range.context.end, &self.buffer)
3760            .is_gt()
3761        {
3762            self.range.context.end
3763        } else {
3764            text_anchor
3765        }
3766    }
3767
3768    fn contains(&self, anchor: &Anchor) -> bool {
3769        Some(self.buffer_id) == anchor.buffer_id
3770            && self
3771                .range
3772                .context
3773                .start
3774                .cmp(&anchor.text_anchor, &self.buffer)
3775                .is_le()
3776            && self
3777                .range
3778                .context
3779                .end
3780                .cmp(&anchor.text_anchor, &self.buffer)
3781                .is_ge()
3782    }
3783
3784    /// The [`Excerpt`]'s start offset in its [`Buffer`]
3785    fn buffer_start_offset(&self) -> usize {
3786        self.range.context.start.to_offset(&self.buffer)
3787    }
3788
3789    /// The [`Excerpt`]'s end offset in its [`Buffer`]
3790    fn buffer_end_offset(&self) -> usize {
3791        self.buffer_start_offset() + self.text_summary.len
3792    }
3793}
3794
3795impl<'a> MultiBufferExcerpt<'a> {
3796    fn new(excerpt: &'a Excerpt, excerpt_offset: usize) -> Self {
3797        MultiBufferExcerpt {
3798            excerpt,
3799            excerpt_offset,
3800        }
3801    }
3802
3803    pub fn buffer(&self) -> &'a BufferSnapshot {
3804        &self.excerpt.buffer
3805    }
3806
3807    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
3808    pub fn map_offset_to_buffer(&self, offset: usize) -> usize {
3809        self.excerpt.buffer_start_offset() + offset.saturating_sub(self.excerpt_offset)
3810    }
3811
3812    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
3813    pub fn map_range_to_buffer(&self, range: Range<usize>) -> Range<usize> {
3814        self.map_offset_to_buffer(range.start)..self.map_offset_to_buffer(range.end)
3815    }
3816
3817    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
3818    pub fn map_offset_from_buffer(&self, buffer_offset: usize) -> usize {
3819        let mut buffer_offset_in_excerpt =
3820            buffer_offset.saturating_sub(self.excerpt.buffer_start_offset());
3821        buffer_offset_in_excerpt =
3822            cmp::min(buffer_offset_in_excerpt, self.excerpt.text_summary.len);
3823
3824        self.excerpt_offset + buffer_offset_in_excerpt
3825    }
3826
3827    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
3828    pub fn map_range_from_buffer(&self, buffer_range: Range<usize>) -> Range<usize> {
3829        self.map_offset_from_buffer(buffer_range.start)
3830            ..self.map_offset_from_buffer(buffer_range.end)
3831    }
3832
3833    /// Returns true if the entirety of the given range is in the buffer's excerpt
3834    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
3835        range.start >= self.excerpt.buffer_start_offset()
3836            && range.end <= self.excerpt.buffer_end_offset()
3837    }
3838}
3839
3840impl ExcerptId {
3841    pub fn min() -> Self {
3842        Self(0)
3843    }
3844
3845    pub fn max() -> Self {
3846        Self(usize::MAX)
3847    }
3848
3849    pub fn to_proto(&self) -> u64 {
3850        self.0 as _
3851    }
3852
3853    pub fn from_proto(proto: u64) -> Self {
3854        Self(proto as _)
3855    }
3856
3857    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
3858        let a = snapshot.excerpt_locator_for_id(*self);
3859        let b = snapshot.excerpt_locator_for_id(*other);
3860        a.cmp(b).then_with(|| self.0.cmp(&other.0))
3861    }
3862}
3863
3864impl Into<usize> for ExcerptId {
3865    fn into(self) -> usize {
3866        self.0
3867    }
3868}
3869
3870impl fmt::Debug for Excerpt {
3871    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3872        f.debug_struct("Excerpt")
3873            .field("id", &self.id)
3874            .field("locator", &self.locator)
3875            .field("buffer_id", &self.buffer_id)
3876            .field("range", &self.range)
3877            .field("text_summary", &self.text_summary)
3878            .field("has_trailing_newline", &self.has_trailing_newline)
3879            .finish()
3880    }
3881}
3882
3883impl sum_tree::Item for Excerpt {
3884    type Summary = ExcerptSummary;
3885
3886    fn summary(&self) -> Self::Summary {
3887        let mut text = self.text_summary.clone();
3888        if self.has_trailing_newline {
3889            text += TextSummary::from("\n");
3890        }
3891        ExcerptSummary {
3892            excerpt_id: self.id,
3893            excerpt_locator: self.locator.clone(),
3894            max_buffer_row: self.max_buffer_row,
3895            text,
3896        }
3897    }
3898}
3899
3900impl sum_tree::Item for ExcerptIdMapping {
3901    type Summary = ExcerptId;
3902
3903    fn summary(&self) -> Self::Summary {
3904        self.id
3905    }
3906}
3907
3908impl sum_tree::KeyedItem for ExcerptIdMapping {
3909    type Key = ExcerptId;
3910
3911    fn key(&self) -> Self::Key {
3912        self.id
3913    }
3914}
3915
3916impl sum_tree::Summary for ExcerptId {
3917    type Context = ();
3918
3919    fn add_summary(&mut self, other: &Self, _: &()) {
3920        *self = *other;
3921    }
3922}
3923
3924impl sum_tree::Summary for ExcerptSummary {
3925    type Context = ();
3926
3927    fn add_summary(&mut self, summary: &Self, _: &()) {
3928        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
3929        self.excerpt_locator = summary.excerpt_locator.clone();
3930        self.text.add_summary(&summary.text, &());
3931        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
3932    }
3933}
3934
3935impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
3936    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3937        *self += &summary.text;
3938    }
3939}
3940
3941impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
3942    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3943        *self += summary.text.len;
3944    }
3945}
3946
3947impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
3948    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3949        Ord::cmp(self, &cursor_location.text.len)
3950    }
3951}
3952
3953impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
3954    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
3955        Ord::cmp(&Some(self), cursor_location)
3956    }
3957}
3958
3959impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
3960    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3961        Ord::cmp(self, &cursor_location.excerpt_locator)
3962    }
3963}
3964
3965impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
3966    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3967        *self += summary.text.len_utf16;
3968    }
3969}
3970
3971impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
3972    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3973        *self += summary.text.lines;
3974    }
3975}
3976
3977impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
3978    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3979        *self += summary.text.lines_utf16()
3980    }
3981}
3982
3983impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
3984    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3985        *self = Some(&summary.excerpt_locator);
3986    }
3987}
3988
3989impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
3990    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3991        *self = Some(summary.excerpt_id);
3992    }
3993}
3994
3995impl<'a> MultiBufferRows<'a> {
3996    pub fn seek(&mut self, row: u32) {
3997        self.buffer_row_range = 0..0;
3998
3999        self.excerpts
4000            .seek_forward(&Point::new(row, 0), Bias::Right, &());
4001        if self.excerpts.item().is_none() {
4002            self.excerpts.prev(&());
4003
4004            if self.excerpts.item().is_none() && row == 0 {
4005                self.buffer_row_range = 0..1;
4006                return;
4007            }
4008        }
4009
4010        if let Some(excerpt) = self.excerpts.item() {
4011            let overshoot = row - self.excerpts.start().row;
4012            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4013            self.buffer_row_range.start = excerpt_start + overshoot;
4014            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
4015        }
4016    }
4017}
4018
4019impl<'a> Iterator for MultiBufferRows<'a> {
4020    type Item = Option<u32>;
4021
4022    fn next(&mut self) -> Option<Self::Item> {
4023        loop {
4024            if !self.buffer_row_range.is_empty() {
4025                let row = Some(self.buffer_row_range.start);
4026                self.buffer_row_range.start += 1;
4027                return Some(row);
4028            }
4029            self.excerpts.item()?;
4030            self.excerpts.next(&());
4031            let excerpt = self.excerpts.item()?;
4032            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4033            self.buffer_row_range.end =
4034                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
4035        }
4036    }
4037}
4038
4039impl<'a> MultiBufferChunks<'a> {
4040    pub fn offset(&self) -> usize {
4041        self.range.start
4042    }
4043
4044    pub fn seek(&mut self, offset: usize) {
4045        self.range.start = offset;
4046        self.excerpts.seek(&offset, Bias::Right, &());
4047        if let Some(excerpt) = self.excerpts.item() {
4048            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4049                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
4050                self.language_aware,
4051            ));
4052        } else {
4053            self.excerpt_chunks = None;
4054        }
4055    }
4056}
4057
4058impl<'a> Iterator for MultiBufferChunks<'a> {
4059    type Item = Chunk<'a>;
4060
4061    fn next(&mut self) -> Option<Self::Item> {
4062        if self.range.is_empty() {
4063            None
4064        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
4065            self.range.start += chunk.text.len();
4066            Some(chunk)
4067        } else {
4068            self.excerpts.next(&());
4069            let excerpt = self.excerpts.item()?;
4070            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4071                0..self.range.end - self.excerpts.start(),
4072                self.language_aware,
4073            ));
4074            self.next()
4075        }
4076    }
4077}
4078
4079impl<'a> MultiBufferBytes<'a> {
4080    fn consume(&mut self, len: usize) {
4081        self.range.start += len;
4082        self.chunk = &self.chunk[len..];
4083
4084        if !self.range.is_empty() && self.chunk.is_empty() {
4085            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4086                self.chunk = chunk;
4087            } else {
4088                self.excerpts.next(&());
4089                if let Some(excerpt) = self.excerpts.item() {
4090                    let mut excerpt_bytes =
4091                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4092                    self.chunk = excerpt_bytes.next().unwrap();
4093                    self.excerpt_bytes = Some(excerpt_bytes);
4094                }
4095            }
4096        }
4097    }
4098}
4099
4100impl<'a> Iterator for MultiBufferBytes<'a> {
4101    type Item = &'a [u8];
4102
4103    fn next(&mut self) -> Option<Self::Item> {
4104        let chunk = self.chunk;
4105        if chunk.is_empty() {
4106            None
4107        } else {
4108            self.consume(chunk.len());
4109            Some(chunk)
4110        }
4111    }
4112}
4113
4114impl<'a> io::Read for MultiBufferBytes<'a> {
4115    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4116        let len = cmp::min(buf.len(), self.chunk.len());
4117        buf[..len].copy_from_slice(&self.chunk[..len]);
4118        if len > 0 {
4119            self.consume(len);
4120        }
4121        Ok(len)
4122    }
4123}
4124
4125impl<'a> ReversedMultiBufferBytes<'a> {
4126    fn consume(&mut self, len: usize) {
4127        self.range.end -= len;
4128        self.chunk = &self.chunk[..self.chunk.len() - len];
4129
4130        if !self.range.is_empty() && self.chunk.is_empty() {
4131            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4132                self.chunk = chunk;
4133            } else {
4134                self.excerpts.next(&());
4135                if let Some(excerpt) = self.excerpts.item() {
4136                    let mut excerpt_bytes =
4137                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4138                    self.chunk = excerpt_bytes.next().unwrap();
4139                    self.excerpt_bytes = Some(excerpt_bytes);
4140                }
4141            }
4142        }
4143    }
4144}
4145
4146impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
4147    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4148        let len = cmp::min(buf.len(), self.chunk.len());
4149        buf[..len].copy_from_slice(&self.chunk[..len]);
4150        buf[..len].reverse();
4151        if len > 0 {
4152            self.consume(len);
4153        }
4154        Ok(len)
4155    }
4156}
4157impl<'a> Iterator for ExcerptBytes<'a> {
4158    type Item = &'a [u8];
4159
4160    fn next(&mut self) -> Option<Self::Item> {
4161        if let Some(chunk) = self.content_bytes.next() {
4162            if !chunk.is_empty() {
4163                return Some(chunk);
4164            }
4165        }
4166
4167        if self.footer_height > 0 {
4168            let result = &NEWLINES[..self.footer_height];
4169            self.footer_height = 0;
4170            return Some(result);
4171        }
4172
4173        None
4174    }
4175}
4176
4177impl<'a> Iterator for ExcerptChunks<'a> {
4178    type Item = Chunk<'a>;
4179
4180    fn next(&mut self) -> Option<Self::Item> {
4181        if let Some(chunk) = self.content_chunks.next() {
4182            return Some(chunk);
4183        }
4184
4185        if self.footer_height > 0 {
4186            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
4187            self.footer_height = 0;
4188            return Some(Chunk {
4189                text,
4190                ..Default::default()
4191            });
4192        }
4193
4194        None
4195    }
4196}
4197
4198impl ToOffset for Point {
4199    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4200        snapshot.point_to_offset(*self)
4201    }
4202}
4203
4204impl ToOffset for usize {
4205    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4206        assert!(*self <= snapshot.len(), "offset is out of range");
4207        *self
4208    }
4209}
4210
4211impl ToOffset for OffsetUtf16 {
4212    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4213        snapshot.offset_utf16_to_offset(*self)
4214    }
4215}
4216
4217impl ToOffset for PointUtf16 {
4218    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4219        snapshot.point_utf16_to_offset(*self)
4220    }
4221}
4222
4223impl ToOffsetUtf16 for OffsetUtf16 {
4224    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4225        *self
4226    }
4227}
4228
4229impl ToOffsetUtf16 for usize {
4230    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4231        snapshot.offset_to_offset_utf16(*self)
4232    }
4233}
4234
4235impl ToPoint for usize {
4236    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
4237        snapshot.offset_to_point(*self)
4238    }
4239}
4240
4241impl ToPoint for Point {
4242    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
4243        *self
4244    }
4245}
4246
4247impl ToPointUtf16 for usize {
4248    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4249        snapshot.offset_to_point_utf16(*self)
4250    }
4251}
4252
4253impl ToPointUtf16 for Point {
4254    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4255        snapshot.point_to_point_utf16(*self)
4256    }
4257}
4258
4259impl ToPointUtf16 for PointUtf16 {
4260    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
4261        *self
4262    }
4263}
4264
4265fn build_excerpt_ranges<T>(
4266    buffer: &BufferSnapshot,
4267    ranges: &[Range<T>],
4268    context_line_count: u32,
4269) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
4270where
4271    T: text::ToPoint,
4272{
4273    let max_point = buffer.max_point();
4274    let mut range_counts = Vec::new();
4275    let mut excerpt_ranges = Vec::new();
4276    let mut range_iter = ranges
4277        .iter()
4278        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
4279        .peekable();
4280    while let Some(range) = range_iter.next() {
4281        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
4282        let mut excerpt_end = Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
4283        let mut ranges_in_excerpt = 1;
4284
4285        while let Some(next_range) = range_iter.peek() {
4286            if next_range.start.row <= excerpt_end.row + context_line_count {
4287                excerpt_end =
4288                    Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
4289                ranges_in_excerpt += 1;
4290                range_iter.next();
4291            } else {
4292                break;
4293            }
4294        }
4295
4296        excerpt_ranges.push(ExcerptRange {
4297            context: excerpt_start..excerpt_end,
4298            primary: Some(range),
4299        });
4300        range_counts.push(ranges_in_excerpt);
4301    }
4302
4303    (excerpt_ranges, range_counts)
4304}
4305
4306#[cfg(test)]
4307mod tests {
4308    use super::*;
4309    use futures::StreamExt;
4310    use gpui::{AppContext, Context, TestAppContext};
4311    use language::{Buffer, Rope};
4312    use parking_lot::RwLock;
4313    use rand::prelude::*;
4314    use settings::SettingsStore;
4315    use std::env;
4316    use util::test::sample_text;
4317
4318    #[gpui::test]
4319    fn test_singleton(cx: &mut AppContext) {
4320        let buffer = cx.new_model(|cx| {
4321            Buffer::new(
4322                0,
4323                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4324                sample_text(6, 6, 'a'),
4325            )
4326        });
4327        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4328
4329        let snapshot = multibuffer.read(cx).snapshot(cx);
4330        assert_eq!(snapshot.text(), buffer.read(cx).text());
4331
4332        assert_eq!(
4333            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4334            (0..buffer.read(cx).row_count())
4335                .map(Some)
4336                .collect::<Vec<_>>()
4337        );
4338
4339        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
4340        let snapshot = multibuffer.read(cx).snapshot(cx);
4341
4342        assert_eq!(snapshot.text(), buffer.read(cx).text());
4343        assert_eq!(
4344            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4345            (0..buffer.read(cx).row_count())
4346                .map(Some)
4347                .collect::<Vec<_>>()
4348        );
4349    }
4350
4351    #[gpui::test]
4352    fn test_remote(cx: &mut AppContext) {
4353        let host_buffer =
4354            cx.new_model(|cx| Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "a"));
4355        let guest_buffer = cx.new_model(|cx| {
4356            let state = host_buffer.read(cx).to_proto();
4357            let ops = cx
4358                .background_executor()
4359                .block(host_buffer.read(cx).serialize_ops(None, cx));
4360            let mut buffer = Buffer::from_proto(1, Capability::ReadWrite, state, None).unwrap();
4361            buffer
4362                .apply_ops(
4363                    ops.into_iter()
4364                        .map(|op| language::proto::deserialize_operation(op).unwrap()),
4365                    cx,
4366                )
4367                .unwrap();
4368            buffer
4369        });
4370        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
4371        let snapshot = multibuffer.read(cx).snapshot(cx);
4372        assert_eq!(snapshot.text(), "a");
4373
4374        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
4375        let snapshot = multibuffer.read(cx).snapshot(cx);
4376        assert_eq!(snapshot.text(), "ab");
4377
4378        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
4379        let snapshot = multibuffer.read(cx).snapshot(cx);
4380        assert_eq!(snapshot.text(), "abc");
4381    }
4382
4383    #[gpui::test]
4384    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
4385        let buffer_1 = cx.new_model(|cx| {
4386            Buffer::new(
4387                0,
4388                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4389                sample_text(6, 6, 'a'),
4390            )
4391        });
4392        let buffer_2 = cx.new_model(|cx| {
4393            Buffer::new(
4394                0,
4395                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4396                sample_text(6, 6, 'g'),
4397            )
4398        });
4399        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4400
4401        let events = Arc::new(RwLock::new(Vec::<Event>::new()));
4402        multibuffer.update(cx, |_, cx| {
4403            let events = events.clone();
4404            cx.subscribe(&multibuffer, move |_, _, event, _| {
4405                if let Event::Edited { .. } = event {
4406                    events.write().push(event.clone())
4407                }
4408            })
4409            .detach();
4410        });
4411
4412        let subscription = multibuffer.update(cx, |multibuffer, cx| {
4413            let subscription = multibuffer.subscribe();
4414            multibuffer.push_excerpts(
4415                buffer_1.clone(),
4416                [ExcerptRange {
4417                    context: Point::new(1, 2)..Point::new(2, 5),
4418                    primary: None,
4419                }],
4420                cx,
4421            );
4422            assert_eq!(
4423                subscription.consume().into_inner(),
4424                [Edit {
4425                    old: 0..0,
4426                    new: 0..10
4427                }]
4428            );
4429
4430            multibuffer.push_excerpts(
4431                buffer_1.clone(),
4432                [ExcerptRange {
4433                    context: Point::new(3, 3)..Point::new(4, 4),
4434                    primary: None,
4435                }],
4436                cx,
4437            );
4438            multibuffer.push_excerpts(
4439                buffer_2.clone(),
4440                [ExcerptRange {
4441                    context: Point::new(3, 1)..Point::new(3, 3),
4442                    primary: None,
4443                }],
4444                cx,
4445            );
4446            assert_eq!(
4447                subscription.consume().into_inner(),
4448                [Edit {
4449                    old: 10..10,
4450                    new: 10..22
4451                }]
4452            );
4453
4454            subscription
4455        });
4456
4457        // Adding excerpts emits an edited event.
4458        assert_eq!(
4459            events.read().as_slice(),
4460            &[
4461                Event::Edited {
4462                    singleton_buffer_edited: false
4463                },
4464                Event::Edited {
4465                    singleton_buffer_edited: false
4466                },
4467                Event::Edited {
4468                    singleton_buffer_edited: false
4469                }
4470            ]
4471        );
4472
4473        let snapshot = multibuffer.read(cx).snapshot(cx);
4474        assert_eq!(
4475            snapshot.text(),
4476            concat!(
4477                "bbbb\n",  // Preserve newlines
4478                "ccccc\n", //
4479                "ddd\n",   //
4480                "eeee\n",  //
4481                "jj"       //
4482            )
4483        );
4484        assert_eq!(
4485            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4486            [Some(1), Some(2), Some(3), Some(4), Some(3)]
4487        );
4488        assert_eq!(
4489            snapshot.buffer_rows(2).collect::<Vec<_>>(),
4490            [Some(3), Some(4), Some(3)]
4491        );
4492        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
4493        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
4494
4495        assert_eq!(
4496            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
4497            &[
4498                (0, "bbbb\nccccc".to_string(), true),
4499                (2, "ddd\neeee".to_string(), false),
4500                (4, "jj".to_string(), true),
4501            ]
4502        );
4503        assert_eq!(
4504            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
4505            &[(0, "bbbb\nccccc".to_string(), true)]
4506        );
4507        assert_eq!(
4508            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
4509            &[]
4510        );
4511        assert_eq!(
4512            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
4513            &[]
4514        );
4515        assert_eq!(
4516            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4517            &[(2, "ddd\neeee".to_string(), false)]
4518        );
4519        assert_eq!(
4520            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4521            &[(2, "ddd\neeee".to_string(), false)]
4522        );
4523        assert_eq!(
4524            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
4525            &[(2, "ddd\neeee".to_string(), false)]
4526        );
4527        assert_eq!(
4528            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
4529            &[(4, "jj".to_string(), true)]
4530        );
4531        assert_eq!(
4532            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
4533            &[]
4534        );
4535
4536        buffer_1.update(cx, |buffer, cx| {
4537            let text = "\n";
4538            buffer.edit(
4539                [
4540                    (Point::new(0, 0)..Point::new(0, 0), text),
4541                    (Point::new(2, 1)..Point::new(2, 3), text),
4542                ],
4543                None,
4544                cx,
4545            );
4546        });
4547
4548        let snapshot = multibuffer.read(cx).snapshot(cx);
4549        assert_eq!(
4550            snapshot.text(),
4551            concat!(
4552                "bbbb\n", // Preserve newlines
4553                "c\n",    //
4554                "cc\n",   //
4555                "ddd\n",  //
4556                "eeee\n", //
4557                "jj"      //
4558            )
4559        );
4560
4561        assert_eq!(
4562            subscription.consume().into_inner(),
4563            [Edit {
4564                old: 6..8,
4565                new: 6..7
4566            }]
4567        );
4568
4569        let snapshot = multibuffer.read(cx).snapshot(cx);
4570        assert_eq!(
4571            snapshot.clip_point(Point::new(0, 5), Bias::Left),
4572            Point::new(0, 4)
4573        );
4574        assert_eq!(
4575            snapshot.clip_point(Point::new(0, 5), Bias::Right),
4576            Point::new(0, 4)
4577        );
4578        assert_eq!(
4579            snapshot.clip_point(Point::new(5, 1), Bias::Right),
4580            Point::new(5, 1)
4581        );
4582        assert_eq!(
4583            snapshot.clip_point(Point::new(5, 2), Bias::Right),
4584            Point::new(5, 2)
4585        );
4586        assert_eq!(
4587            snapshot.clip_point(Point::new(5, 3), Bias::Right),
4588            Point::new(5, 2)
4589        );
4590
4591        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
4592            let (buffer_2_excerpt_id, _) =
4593                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
4594            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
4595            multibuffer.snapshot(cx)
4596        });
4597
4598        assert_eq!(
4599            snapshot.text(),
4600            concat!(
4601                "bbbb\n", // Preserve newlines
4602                "c\n",    //
4603                "cc\n",   //
4604                "ddd\n",  //
4605                "eeee",   //
4606            )
4607        );
4608
4609        fn boundaries_in_range(
4610            range: Range<Point>,
4611            snapshot: &MultiBufferSnapshot,
4612        ) -> Vec<(u32, String, bool)> {
4613            snapshot
4614                .excerpt_boundaries_in_range(range)
4615                .map(|boundary| {
4616                    (
4617                        boundary.row,
4618                        boundary
4619                            .buffer
4620                            .text_for_range(boundary.range.context)
4621                            .collect::<String>(),
4622                        boundary.starts_new_buffer,
4623                    )
4624                })
4625                .collect::<Vec<_>>()
4626        }
4627    }
4628
4629    #[gpui::test]
4630    fn test_excerpt_events(cx: &mut AppContext) {
4631        let buffer_1 = cx.new_model(|cx| {
4632            Buffer::new(
4633                0,
4634                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4635                sample_text(10, 3, 'a'),
4636            )
4637        });
4638        let buffer_2 = cx.new_model(|cx| {
4639            Buffer::new(
4640                0,
4641                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4642                sample_text(10, 3, 'm'),
4643            )
4644        });
4645
4646        let leader_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4647        let follower_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4648        let follower_edit_event_count = Arc::new(RwLock::new(0));
4649
4650        follower_multibuffer.update(cx, |_, cx| {
4651            let follower_edit_event_count = follower_edit_event_count.clone();
4652            cx.subscribe(
4653                &leader_multibuffer,
4654                move |follower, _, event, cx| match event.clone() {
4655                    Event::ExcerptsAdded {
4656                        buffer,
4657                        predecessor,
4658                        excerpts,
4659                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
4660                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
4661                    Event::Edited { .. } => {
4662                        *follower_edit_event_count.write() += 1;
4663                    }
4664                    _ => {}
4665                },
4666            )
4667            .detach();
4668        });
4669
4670        leader_multibuffer.update(cx, |leader, cx| {
4671            leader.push_excerpts(
4672                buffer_1.clone(),
4673                [
4674                    ExcerptRange {
4675                        context: 0..8,
4676                        primary: None,
4677                    },
4678                    ExcerptRange {
4679                        context: 12..16,
4680                        primary: None,
4681                    },
4682                ],
4683                cx,
4684            );
4685            leader.insert_excerpts_after(
4686                leader.excerpt_ids()[0],
4687                buffer_2.clone(),
4688                [
4689                    ExcerptRange {
4690                        context: 0..5,
4691                        primary: None,
4692                    },
4693                    ExcerptRange {
4694                        context: 10..15,
4695                        primary: None,
4696                    },
4697                ],
4698                cx,
4699            )
4700        });
4701        assert_eq!(
4702            leader_multibuffer.read(cx).snapshot(cx).text(),
4703            follower_multibuffer.read(cx).snapshot(cx).text(),
4704        );
4705        assert_eq!(*follower_edit_event_count.read(), 2);
4706
4707        leader_multibuffer.update(cx, |leader, cx| {
4708            let excerpt_ids = leader.excerpt_ids();
4709            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
4710        });
4711        assert_eq!(
4712            leader_multibuffer.read(cx).snapshot(cx).text(),
4713            follower_multibuffer.read(cx).snapshot(cx).text(),
4714        );
4715        assert_eq!(*follower_edit_event_count.read(), 3);
4716
4717        // Removing an empty set of excerpts is a noop.
4718        leader_multibuffer.update(cx, |leader, cx| {
4719            leader.remove_excerpts([], cx);
4720        });
4721        assert_eq!(
4722            leader_multibuffer.read(cx).snapshot(cx).text(),
4723            follower_multibuffer.read(cx).snapshot(cx).text(),
4724        );
4725        assert_eq!(*follower_edit_event_count.read(), 3);
4726
4727        // Adding an empty set of excerpts is a noop.
4728        leader_multibuffer.update(cx, |leader, cx| {
4729            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
4730        });
4731        assert_eq!(
4732            leader_multibuffer.read(cx).snapshot(cx).text(),
4733            follower_multibuffer.read(cx).snapshot(cx).text(),
4734        );
4735        assert_eq!(*follower_edit_event_count.read(), 3);
4736
4737        leader_multibuffer.update(cx, |leader, cx| {
4738            leader.clear(cx);
4739        });
4740        assert_eq!(
4741            leader_multibuffer.read(cx).snapshot(cx).text(),
4742            follower_multibuffer.read(cx).snapshot(cx).text(),
4743        );
4744        assert_eq!(*follower_edit_event_count.read(), 4);
4745    }
4746
4747    #[gpui::test]
4748    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
4749        let buffer = cx.new_model(|cx| {
4750            Buffer::new(
4751                0,
4752                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4753                sample_text(20, 3, 'a'),
4754            )
4755        });
4756        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4757        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
4758            multibuffer.push_excerpts_with_context_lines(
4759                buffer.clone(),
4760                vec![
4761                    Point::new(3, 2)..Point::new(4, 2),
4762                    Point::new(7, 1)..Point::new(7, 3),
4763                    Point::new(15, 0)..Point::new(15, 0),
4764                ],
4765                2,
4766                cx,
4767            )
4768        });
4769
4770        let snapshot = multibuffer.read(cx).snapshot(cx);
4771        assert_eq!(
4772            snapshot.text(),
4773            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4774        );
4775
4776        assert_eq!(
4777            anchor_ranges
4778                .iter()
4779                .map(|range| range.to_point(&snapshot))
4780                .collect::<Vec<_>>(),
4781            vec![
4782                Point::new(2, 2)..Point::new(3, 2),
4783                Point::new(6, 1)..Point::new(6, 3),
4784                Point::new(12, 0)..Point::new(12, 0)
4785            ]
4786        );
4787    }
4788
4789    #[gpui::test]
4790    async fn test_stream_excerpts_with_context_lines(cx: &mut TestAppContext) {
4791        let buffer = cx.new_model(|cx| {
4792            Buffer::new(
4793                0,
4794                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4795                sample_text(20, 3, 'a'),
4796            )
4797        });
4798        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4799        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
4800            let snapshot = buffer.read(cx);
4801            let ranges = vec![
4802                snapshot.anchor_before(Point::new(3, 2))..snapshot.anchor_before(Point::new(4, 2)),
4803                snapshot.anchor_before(Point::new(7, 1))..snapshot.anchor_before(Point::new(7, 3)),
4804                snapshot.anchor_before(Point::new(15, 0))
4805                    ..snapshot.anchor_before(Point::new(15, 0)),
4806            ];
4807            multibuffer.stream_excerpts_with_context_lines(buffer.clone(), ranges, 2, cx)
4808        });
4809
4810        let anchor_ranges = anchor_ranges.collect::<Vec<_>>().await;
4811
4812        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
4813        assert_eq!(
4814            snapshot.text(),
4815            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4816        );
4817
4818        assert_eq!(
4819            anchor_ranges
4820                .iter()
4821                .map(|range| range.to_point(&snapshot))
4822                .collect::<Vec<_>>(),
4823            vec![
4824                Point::new(2, 2)..Point::new(3, 2),
4825                Point::new(6, 1)..Point::new(6, 3),
4826                Point::new(12, 0)..Point::new(12, 0)
4827            ]
4828        );
4829    }
4830
4831    #[gpui::test]
4832    fn test_empty_multibuffer(cx: &mut AppContext) {
4833        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4834
4835        let snapshot = multibuffer.read(cx).snapshot(cx);
4836        assert_eq!(snapshot.text(), "");
4837        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
4838        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
4839    }
4840
4841    #[gpui::test]
4842    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
4843        let buffer = cx.new_model(|cx| {
4844            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4845        });
4846        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4847        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4848        buffer.update(cx, |buffer, cx| {
4849            buffer.edit([(0..0, "X")], None, cx);
4850            buffer.edit([(5..5, "Y")], None, cx);
4851        });
4852        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4853
4854        assert_eq!(old_snapshot.text(), "abcd");
4855        assert_eq!(new_snapshot.text(), "XabcdY");
4856
4857        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4858        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4859        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
4860        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
4861    }
4862
4863    #[gpui::test]
4864    fn test_multibuffer_anchors(cx: &mut AppContext) {
4865        let buffer_1 = cx.new_model(|cx| {
4866            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4867        });
4868        let buffer_2 = cx.new_model(|cx| {
4869            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "efghi")
4870        });
4871        let multibuffer = cx.new_model(|cx| {
4872            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
4873            multibuffer.push_excerpts(
4874                buffer_1.clone(),
4875                [ExcerptRange {
4876                    context: 0..4,
4877                    primary: None,
4878                }],
4879                cx,
4880            );
4881            multibuffer.push_excerpts(
4882                buffer_2.clone(),
4883                [ExcerptRange {
4884                    context: 0..5,
4885                    primary: None,
4886                }],
4887                cx,
4888            );
4889            multibuffer
4890        });
4891        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4892
4893        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
4894        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
4895        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4896        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4897        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4898        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4899
4900        buffer_1.update(cx, |buffer, cx| {
4901            buffer.edit([(0..0, "W")], None, cx);
4902            buffer.edit([(5..5, "X")], None, cx);
4903        });
4904        buffer_2.update(cx, |buffer, cx| {
4905            buffer.edit([(0..0, "Y")], None, cx);
4906            buffer.edit([(6..6, "Z")], None, cx);
4907        });
4908        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4909
4910        assert_eq!(old_snapshot.text(), "abcd\nefghi");
4911        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
4912
4913        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4914        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4915        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
4916        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
4917        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
4918        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
4919        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
4920        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
4921        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
4922        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
4923    }
4924
4925    #[gpui::test]
4926    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
4927        let buffer_1 = cx.new_model(|cx| {
4928            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4929        });
4930        let buffer_2 = cx.new_model(|cx| {
4931            Buffer::new(
4932                0,
4933                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4934                "ABCDEFGHIJKLMNOP",
4935            )
4936        });
4937        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4938
4939        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
4940        // Add an excerpt from buffer 1 that spans this new insertion.
4941        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
4942        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
4943            multibuffer
4944                .push_excerpts(
4945                    buffer_1.clone(),
4946                    [ExcerptRange {
4947                        context: 0..7,
4948                        primary: None,
4949                    }],
4950                    cx,
4951                )
4952                .pop()
4953                .unwrap()
4954        });
4955
4956        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
4957        assert_eq!(snapshot_1.text(), "abcd123");
4958
4959        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
4960        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
4961            multibuffer.remove_excerpts([excerpt_id_1], cx);
4962            let mut ids = multibuffer
4963                .push_excerpts(
4964                    buffer_2.clone(),
4965                    [
4966                        ExcerptRange {
4967                            context: 0..4,
4968                            primary: None,
4969                        },
4970                        ExcerptRange {
4971                            context: 6..10,
4972                            primary: None,
4973                        },
4974                        ExcerptRange {
4975                            context: 12..16,
4976                            primary: None,
4977                        },
4978                    ],
4979                    cx,
4980                )
4981                .into_iter();
4982            (ids.next().unwrap(), ids.next().unwrap())
4983        });
4984        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
4985        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
4986
4987        // The old excerpt id doesn't get reused.
4988        assert_ne!(excerpt_id_2, excerpt_id_1);
4989
4990        // Resolve some anchors from the previous snapshot in the new snapshot.
4991        // The current excerpts are from a different buffer, so we don't attempt to
4992        // resolve the old text anchor in the new buffer.
4993        assert_eq!(
4994            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
4995            0
4996        );
4997        assert_eq!(
4998            snapshot_2.summaries_for_anchors::<usize, _>(&[
4999                snapshot_1.anchor_before(2),
5000                snapshot_1.anchor_after(3)
5001            ]),
5002            vec![0, 0]
5003        );
5004
5005        // Refresh anchors from the old snapshot. The return value indicates that both
5006        // anchors lost their original excerpt.
5007        let refresh =
5008            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
5009        assert_eq!(
5010            refresh,
5011            &[
5012                (0, snapshot_2.anchor_before(0), false),
5013                (1, snapshot_2.anchor_after(0), false),
5014            ]
5015        );
5016
5017        // Replace the middle excerpt with a smaller excerpt in buffer 2,
5018        // that intersects the old excerpt.
5019        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
5020            multibuffer.remove_excerpts([excerpt_id_3], cx);
5021            multibuffer
5022                .insert_excerpts_after(
5023                    excerpt_id_2,
5024                    buffer_2.clone(),
5025                    [ExcerptRange {
5026                        context: 5..8,
5027                        primary: None,
5028                    }],
5029                    cx,
5030                )
5031                .pop()
5032                .unwrap()
5033        });
5034
5035        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
5036        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
5037        assert_ne!(excerpt_id_5, excerpt_id_3);
5038
5039        // Resolve some anchors from the previous snapshot in the new snapshot.
5040        // The third anchor can't be resolved, since its excerpt has been removed,
5041        // so it resolves to the same position as its predecessor.
5042        let anchors = [
5043            snapshot_2.anchor_before(0),
5044            snapshot_2.anchor_after(2),
5045            snapshot_2.anchor_after(6),
5046            snapshot_2.anchor_after(14),
5047        ];
5048        assert_eq!(
5049            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
5050            &[0, 2, 9, 13]
5051        );
5052
5053        let new_anchors = snapshot_3.refresh_anchors(&anchors);
5054        assert_eq!(
5055            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
5056            &[(0, true), (1, true), (2, true), (3, true)]
5057        );
5058        assert_eq!(
5059            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
5060            &[0, 2, 7, 13]
5061        );
5062    }
5063
5064    #[gpui::test(iterations = 100)]
5065    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
5066        let operations = env::var("OPERATIONS")
5067            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
5068            .unwrap_or(10);
5069
5070        let mut buffers: Vec<Model<Buffer>> = Vec::new();
5071        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5072        let mut excerpt_ids = Vec::<ExcerptId>::new();
5073        let mut expected_excerpts = Vec::<(Model<Buffer>, Range<text::Anchor>)>::new();
5074        let mut anchors = Vec::new();
5075        let mut old_versions = Vec::new();
5076
5077        for _ in 0..operations {
5078            match rng.gen_range(0..100) {
5079                0..=19 if !buffers.is_empty() => {
5080                    let buffer = buffers.choose(&mut rng).unwrap();
5081                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
5082                }
5083                20..=29 if !expected_excerpts.is_empty() => {
5084                    let mut ids_to_remove = vec![];
5085                    for _ in 0..rng.gen_range(1..=3) {
5086                        if expected_excerpts.is_empty() {
5087                            break;
5088                        }
5089
5090                        let ix = rng.gen_range(0..expected_excerpts.len());
5091                        ids_to_remove.push(excerpt_ids.remove(ix));
5092                        let (buffer, range) = expected_excerpts.remove(ix);
5093                        let buffer = buffer.read(cx);
5094                        log::info!(
5095                            "Removing excerpt {}: {:?}",
5096                            ix,
5097                            buffer
5098                                .text_for_range(range.to_offset(buffer))
5099                                .collect::<String>(),
5100                        );
5101                    }
5102                    let snapshot = multibuffer.read(cx).read(cx);
5103                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(&b, &snapshot));
5104                    drop(snapshot);
5105                    multibuffer.update(cx, |multibuffer, cx| {
5106                        multibuffer.remove_excerpts(ids_to_remove, cx)
5107                    });
5108                }
5109                30..=39 if !expected_excerpts.is_empty() => {
5110                    let multibuffer = multibuffer.read(cx).read(cx);
5111                    let offset =
5112                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
5113                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
5114                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
5115                    anchors.push(multibuffer.anchor_at(offset, bias));
5116                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
5117                }
5118                40..=44 if !anchors.is_empty() => {
5119                    let multibuffer = multibuffer.read(cx).read(cx);
5120                    let prev_len = anchors.len();
5121                    anchors = multibuffer
5122                        .refresh_anchors(&anchors)
5123                        .into_iter()
5124                        .map(|a| a.1)
5125                        .collect();
5126
5127                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
5128                    // overshoot its boundaries.
5129                    assert_eq!(anchors.len(), prev_len);
5130                    for anchor in &anchors {
5131                        if anchor.excerpt_id == ExcerptId::min()
5132                            || anchor.excerpt_id == ExcerptId::max()
5133                        {
5134                            continue;
5135                        }
5136
5137                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
5138                        assert_eq!(excerpt.id, anchor.excerpt_id);
5139                        assert!(excerpt.contains(anchor));
5140                    }
5141                }
5142                _ => {
5143                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
5144                        let base_text = util::RandomCharIter::new(&mut rng)
5145                            .take(10)
5146                            .collect::<String>();
5147                        buffers.push(cx.new_model(|cx| {
5148                            Buffer::new(
5149                                0,
5150                                BufferId::new(cx.entity_id().as_u64()).unwrap(),
5151                                base_text,
5152                            )
5153                        }));
5154                        buffers.last().unwrap()
5155                    } else {
5156                        buffers.choose(&mut rng).unwrap()
5157                    };
5158
5159                    let buffer = buffer_handle.read(cx);
5160                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
5161                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5162                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
5163                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
5164                    let prev_excerpt_id = excerpt_ids
5165                        .get(prev_excerpt_ix)
5166                        .cloned()
5167                        .unwrap_or_else(ExcerptId::max);
5168                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
5169
5170                    log::info!(
5171                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
5172                        excerpt_ix,
5173                        expected_excerpts.len(),
5174                        buffer_handle.read(cx).remote_id(),
5175                        buffer.text(),
5176                        start_ix..end_ix,
5177                        &buffer.text()[start_ix..end_ix]
5178                    );
5179
5180                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
5181                        multibuffer
5182                            .insert_excerpts_after(
5183                                prev_excerpt_id,
5184                                buffer_handle.clone(),
5185                                [ExcerptRange {
5186                                    context: start_ix..end_ix,
5187                                    primary: None,
5188                                }],
5189                                cx,
5190                            )
5191                            .pop()
5192                            .unwrap()
5193                    });
5194
5195                    excerpt_ids.insert(excerpt_ix, excerpt_id);
5196                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
5197                }
5198            }
5199
5200            if rng.gen_bool(0.3) {
5201                multibuffer.update(cx, |multibuffer, cx| {
5202                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
5203                })
5204            }
5205
5206            let snapshot = multibuffer.read(cx).snapshot(cx);
5207
5208            let mut excerpt_starts = Vec::new();
5209            let mut expected_text = String::new();
5210            let mut expected_buffer_rows = Vec::new();
5211            for (buffer, range) in &expected_excerpts {
5212                let buffer = buffer.read(cx);
5213                let buffer_range = range.to_offset(buffer);
5214
5215                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
5216                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
5217                expected_text.push('\n');
5218
5219                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
5220                    ..=buffer.offset_to_point(buffer_range.end).row;
5221                for row in buffer_row_range {
5222                    expected_buffer_rows.push(Some(row));
5223                }
5224            }
5225            // Remove final trailing newline.
5226            if !expected_excerpts.is_empty() {
5227                expected_text.pop();
5228            }
5229
5230            // Always report one buffer row
5231            if expected_buffer_rows.is_empty() {
5232                expected_buffer_rows.push(Some(0));
5233            }
5234
5235            assert_eq!(snapshot.text(), expected_text);
5236            log::info!("MultiBuffer text: {:?}", expected_text);
5237
5238            assert_eq!(
5239                snapshot.buffer_rows(0).collect::<Vec<_>>(),
5240                expected_buffer_rows,
5241            );
5242
5243            for _ in 0..5 {
5244                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
5245                assert_eq!(
5246                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
5247                    &expected_buffer_rows[start_row..],
5248                    "buffer_rows({})",
5249                    start_row
5250                );
5251            }
5252
5253            assert_eq!(
5254                snapshot.max_buffer_row(),
5255                expected_buffer_rows.into_iter().flatten().max().unwrap()
5256            );
5257
5258            let mut excerpt_starts = excerpt_starts.into_iter();
5259            for (buffer, range) in &expected_excerpts {
5260                let buffer = buffer.read(cx);
5261                let buffer_id = buffer.remote_id();
5262                let buffer_range = range.to_offset(buffer);
5263                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
5264                let buffer_start_point_utf16 =
5265                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
5266
5267                let excerpt_start = excerpt_starts.next().unwrap();
5268                let mut offset = excerpt_start.len;
5269                let mut buffer_offset = buffer_range.start;
5270                let mut point = excerpt_start.lines;
5271                let mut buffer_point = buffer_start_point;
5272                let mut point_utf16 = excerpt_start.lines_utf16();
5273                let mut buffer_point_utf16 = buffer_start_point_utf16;
5274                for ch in buffer
5275                    .snapshot()
5276                    .chunks(buffer_range.clone(), false)
5277                    .flat_map(|c| c.text.chars())
5278                {
5279                    for _ in 0..ch.len_utf8() {
5280                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
5281                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
5282                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
5283                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
5284                        assert_eq!(
5285                            left_offset,
5286                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
5287                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
5288                            offset,
5289                            buffer_id,
5290                            buffer_offset,
5291                        );
5292                        assert_eq!(
5293                            right_offset,
5294                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
5295                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
5296                            offset,
5297                            buffer_id,
5298                            buffer_offset,
5299                        );
5300
5301                        let left_point = snapshot.clip_point(point, Bias::Left);
5302                        let right_point = snapshot.clip_point(point, Bias::Right);
5303                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
5304                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
5305                        assert_eq!(
5306                            left_point,
5307                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
5308                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
5309                            point,
5310                            buffer_id,
5311                            buffer_point,
5312                        );
5313                        assert_eq!(
5314                            right_point,
5315                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
5316                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
5317                            point,
5318                            buffer_id,
5319                            buffer_point,
5320                        );
5321
5322                        assert_eq!(
5323                            snapshot.point_to_offset(left_point),
5324                            left_offset,
5325                            "point_to_offset({:?})",
5326                            left_point,
5327                        );
5328                        assert_eq!(
5329                            snapshot.offset_to_point(left_offset),
5330                            left_point,
5331                            "offset_to_point({:?})",
5332                            left_offset,
5333                        );
5334
5335                        offset += 1;
5336                        buffer_offset += 1;
5337                        if ch == '\n' {
5338                            point += Point::new(1, 0);
5339                            buffer_point += Point::new(1, 0);
5340                        } else {
5341                            point += Point::new(0, 1);
5342                            buffer_point += Point::new(0, 1);
5343                        }
5344                    }
5345
5346                    for _ in 0..ch.len_utf16() {
5347                        let left_point_utf16 =
5348                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
5349                        let right_point_utf16 =
5350                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
5351                        let buffer_left_point_utf16 =
5352                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
5353                        let buffer_right_point_utf16 =
5354                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
5355                        assert_eq!(
5356                            left_point_utf16,
5357                            excerpt_start.lines_utf16()
5358                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
5359                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
5360                            point_utf16,
5361                            buffer_id,
5362                            buffer_point_utf16,
5363                        );
5364                        assert_eq!(
5365                            right_point_utf16,
5366                            excerpt_start.lines_utf16()
5367                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
5368                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
5369                            point_utf16,
5370                            buffer_id,
5371                            buffer_point_utf16,
5372                        );
5373
5374                        if ch == '\n' {
5375                            point_utf16 += PointUtf16::new(1, 0);
5376                            buffer_point_utf16 += PointUtf16::new(1, 0);
5377                        } else {
5378                            point_utf16 += PointUtf16::new(0, 1);
5379                            buffer_point_utf16 += PointUtf16::new(0, 1);
5380                        }
5381                    }
5382                }
5383            }
5384
5385            for (row, line) in expected_text.split('\n').enumerate() {
5386                assert_eq!(
5387                    snapshot.line_len(row as u32),
5388                    line.len() as u32,
5389                    "line_len({}).",
5390                    row
5391                );
5392            }
5393
5394            let text_rope = Rope::from(expected_text.as_str());
5395            for _ in 0..10 {
5396                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5397                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5398
5399                let text_for_range = snapshot
5400                    .text_for_range(start_ix..end_ix)
5401                    .collect::<String>();
5402                assert_eq!(
5403                    text_for_range,
5404                    &expected_text[start_ix..end_ix],
5405                    "incorrect text for range {:?}",
5406                    start_ix..end_ix
5407                );
5408
5409                let excerpted_buffer_ranges = multibuffer
5410                    .read(cx)
5411                    .range_to_buffer_ranges(start_ix..end_ix, cx);
5412                let excerpted_buffers_text = excerpted_buffer_ranges
5413                    .iter()
5414                    .map(|(buffer, buffer_range, _)| {
5415                        buffer
5416                            .read(cx)
5417                            .text_for_range(buffer_range.clone())
5418                            .collect::<String>()
5419                    })
5420                    .collect::<Vec<_>>()
5421                    .join("\n");
5422                assert_eq!(excerpted_buffers_text, text_for_range);
5423                if !expected_excerpts.is_empty() {
5424                    assert!(!excerpted_buffer_ranges.is_empty());
5425                }
5426
5427                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
5428                assert_eq!(
5429                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
5430                    expected_summary,
5431                    "incorrect summary for range {:?}",
5432                    start_ix..end_ix
5433                );
5434            }
5435
5436            // Anchor resolution
5437            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
5438            assert_eq!(anchors.len(), summaries.len());
5439            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
5440                assert!(resolved_offset <= snapshot.len());
5441                assert_eq!(
5442                    snapshot.summary_for_anchor::<usize>(anchor),
5443                    resolved_offset
5444                );
5445            }
5446
5447            for _ in 0..10 {
5448                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5449                assert_eq!(
5450                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
5451                    expected_text[..end_ix].chars().rev().collect::<String>(),
5452                );
5453            }
5454
5455            for _ in 0..10 {
5456                let end_ix = rng.gen_range(0..=text_rope.len());
5457                let start_ix = rng.gen_range(0..=end_ix);
5458                assert_eq!(
5459                    snapshot
5460                        .bytes_in_range(start_ix..end_ix)
5461                        .flatten()
5462                        .copied()
5463                        .collect::<Vec<_>>(),
5464                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
5465                    "bytes_in_range({:?})",
5466                    start_ix..end_ix,
5467                );
5468            }
5469        }
5470
5471        let snapshot = multibuffer.read(cx).snapshot(cx);
5472        for (old_snapshot, subscription) in old_versions {
5473            let edits = subscription.consume().into_inner();
5474
5475            log::info!(
5476                "applying subscription edits to old text: {:?}: {:?}",
5477                old_snapshot.text(),
5478                edits,
5479            );
5480
5481            let mut text = old_snapshot.text();
5482            for edit in edits {
5483                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
5484                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
5485            }
5486            assert_eq!(text.to_string(), snapshot.text());
5487        }
5488    }
5489
5490    #[gpui::test]
5491    fn test_history(cx: &mut AppContext) {
5492        let test_settings = SettingsStore::test(cx);
5493        cx.set_global(test_settings);
5494
5495        let buffer_1 = cx.new_model(|cx| {
5496            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "1234")
5497        });
5498        let buffer_2 = cx.new_model(|cx| {
5499            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "5678")
5500        });
5501        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5502        let group_interval = multibuffer.read(cx).history.group_interval;
5503        multibuffer.update(cx, |multibuffer, cx| {
5504            multibuffer.push_excerpts(
5505                buffer_1.clone(),
5506                [ExcerptRange {
5507                    context: 0..buffer_1.read(cx).len(),
5508                    primary: None,
5509                }],
5510                cx,
5511            );
5512            multibuffer.push_excerpts(
5513                buffer_2.clone(),
5514                [ExcerptRange {
5515                    context: 0..buffer_2.read(cx).len(),
5516                    primary: None,
5517                }],
5518                cx,
5519            );
5520        });
5521
5522        let mut now = Instant::now();
5523
5524        multibuffer.update(cx, |multibuffer, cx| {
5525            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
5526            multibuffer.edit(
5527                [
5528                    (Point::new(0, 0)..Point::new(0, 0), "A"),
5529                    (Point::new(1, 0)..Point::new(1, 0), "A"),
5530                ],
5531                None,
5532                cx,
5533            );
5534            multibuffer.edit(
5535                [
5536                    (Point::new(0, 1)..Point::new(0, 1), "B"),
5537                    (Point::new(1, 1)..Point::new(1, 1), "B"),
5538                ],
5539                None,
5540                cx,
5541            );
5542            multibuffer.end_transaction_at(now, cx);
5543            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5544
5545            // Edit buffer 1 through the multibuffer
5546            now += 2 * group_interval;
5547            multibuffer.start_transaction_at(now, cx);
5548            multibuffer.edit([(2..2, "C")], None, cx);
5549            multibuffer.end_transaction_at(now, cx);
5550            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
5551
5552            // Edit buffer 1 independently
5553            buffer_1.update(cx, |buffer_1, cx| {
5554                buffer_1.start_transaction_at(now);
5555                buffer_1.edit([(3..3, "D")], None, cx);
5556                buffer_1.end_transaction_at(now, cx);
5557
5558                now += 2 * group_interval;
5559                buffer_1.start_transaction_at(now);
5560                buffer_1.edit([(4..4, "E")], None, cx);
5561                buffer_1.end_transaction_at(now, cx);
5562            });
5563            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5564
5565            // An undo in the multibuffer undoes the multibuffer transaction
5566            // and also any individual buffer edits that have occurred since
5567            // that transaction.
5568            multibuffer.undo(cx);
5569            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5570
5571            multibuffer.undo(cx);
5572            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5573
5574            multibuffer.redo(cx);
5575            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5576
5577            multibuffer.redo(cx);
5578            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5579
5580            // Undo buffer 2 independently.
5581            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
5582            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
5583
5584            // An undo in the multibuffer undoes the components of the
5585            // the last multibuffer transaction that are not already undone.
5586            multibuffer.undo(cx);
5587            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
5588
5589            multibuffer.undo(cx);
5590            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5591
5592            multibuffer.redo(cx);
5593            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5594
5595            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
5596            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5597
5598            // Redo stack gets cleared after an edit.
5599            now += 2 * group_interval;
5600            multibuffer.start_transaction_at(now, cx);
5601            multibuffer.edit([(0..0, "X")], None, cx);
5602            multibuffer.end_transaction_at(now, cx);
5603            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5604            multibuffer.redo(cx);
5605            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5606            multibuffer.undo(cx);
5607            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5608            multibuffer.undo(cx);
5609            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5610
5611            // Transactions can be grouped manually.
5612            multibuffer.redo(cx);
5613            multibuffer.redo(cx);
5614            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5615            multibuffer.group_until_transaction(transaction_1, cx);
5616            multibuffer.undo(cx);
5617            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5618            multibuffer.redo(cx);
5619            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5620        });
5621    }
5622}