multi_buffer.rs

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