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