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;
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        let mut lines_advance = 0;
2639        let mut cursor = self.excerpts.filter::<_, ExcerptSummary>(move |summary| {
2640            let filter = summary.text.lines.row + lines_advance >= row_range.start
2641                && lines_advance <= row_range.end;
2642            lines_advance += summary.text.lines.row;
2643            filter
2644        });
2645
2646        let mut lines_advance = 0;
2647        std::iter::from_fn(move || {
2648            cursor.next(&());
2649            let excerpt = cursor.item()?;
2650            let summary = cursor.item_summary()?;
2651
2652            let range = excerpt.range.context.clone();
2653            let range_start_row = range.start.to_point(&excerpt.buffer).row;
2654            let range_end_row = range.end.to_point(&excerpt.buffer).row;
2655
2656            let hunks = excerpt.buffer.git_diff_hunks_in_range(range, reversed).map(
2657                move |mut hunk| {
2658                    hunk.buffer_range.start = hunk.buffer_range.start.max(range_start_row)
2659                        - range_start_row
2660                        + lines_advance;
2661                    hunk.buffer_range.end = hunk.buffer_range.end.min(range_end_row + 1)
2662                        - range_start_row
2663                        + lines_advance;
2664                    hunk
2665                },
2666            );
2667
2668            lines_advance += summary.text.lines.row;
2669            Some(hunks)
2670        })
2671        .flatten()
2672    }
2673
2674    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2675        let range = range.start.to_offset(self)..range.end.to_offset(self);
2676
2677        let mut cursor = self.excerpts.cursor::<usize>();
2678        cursor.seek(&range.start, Bias::Right, &());
2679        let start_excerpt = cursor.item();
2680
2681        cursor.seek(&range.end, Bias::Right, &());
2682        let end_excerpt = cursor.item();
2683
2684        start_excerpt
2685            .zip(end_excerpt)
2686            .and_then(|(start_excerpt, end_excerpt)| {
2687                if start_excerpt.id != end_excerpt.id {
2688                    return None;
2689                }
2690
2691                let excerpt_buffer_start = start_excerpt
2692                    .range
2693                    .context
2694                    .start
2695                    .to_offset(&start_excerpt.buffer);
2696                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.len;
2697
2698                let start_in_buffer =
2699                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2700                let end_in_buffer =
2701                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2702                let mut ancestor_buffer_range = start_excerpt
2703                    .buffer
2704                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2705                ancestor_buffer_range.start =
2706                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2707                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2708
2709                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
2710                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
2711                Some(start..end)
2712            })
2713    }
2714
2715    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2716        let (excerpt_id, _, buffer) = self.as_singleton()?;
2717        let outline = buffer.outline(theme)?;
2718        Some(Outline::new(
2719            outline
2720                .items
2721                .into_iter()
2722                .map(|item| OutlineItem {
2723                    depth: item.depth,
2724                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
2725                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
2726                    text: item.text,
2727                    highlight_ranges: item.highlight_ranges,
2728                    name_ranges: item.name_ranges,
2729                })
2730                .collect(),
2731        ))
2732    }
2733
2734    pub fn symbols_containing<T: ToOffset>(
2735        &self,
2736        offset: T,
2737        theme: Option<&SyntaxTheme>,
2738    ) -> Option<(usize, Vec<OutlineItem<Anchor>>)> {
2739        let anchor = self.anchor_before(offset);
2740        let excerpt_id = anchor.excerpt_id();
2741        let excerpt = self.excerpt(excerpt_id)?;
2742        Some((
2743            excerpt.buffer_id,
2744            excerpt
2745                .buffer
2746                .symbols_containing(anchor.text_anchor, theme)
2747                .into_iter()
2748                .flatten()
2749                .map(|item| OutlineItem {
2750                    depth: item.depth,
2751                    range: self.anchor_in_excerpt(excerpt_id, item.range.start)
2752                        ..self.anchor_in_excerpt(excerpt_id, item.range.end),
2753                    text: item.text,
2754                    highlight_ranges: item.highlight_ranges,
2755                    name_ranges: item.name_ranges,
2756                })
2757                .collect(),
2758        ))
2759    }
2760
2761    fn excerpt_locator_for_id<'a>(&'a self, id: ExcerptId) -> &'a Locator {
2762        if id == ExcerptId::min() {
2763            Locator::min_ref()
2764        } else if id == ExcerptId::max() {
2765            Locator::max_ref()
2766        } else {
2767            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
2768            cursor.seek(&id, Bias::Left, &());
2769            if let Some(entry) = cursor.item() {
2770                if entry.id == id {
2771                    return &entry.locator;
2772                }
2773            }
2774            panic!("invalid excerpt id {:?}", id)
2775        }
2776    }
2777
2778    fn excerpt<'a>(&'a self, excerpt_id: ExcerptId) -> Option<&'a Excerpt> {
2779        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2780        let locator = self.excerpt_locator_for_id(excerpt_id);
2781        cursor.seek(&Some(locator), Bias::Left, &());
2782        if let Some(excerpt) = cursor.item() {
2783            if excerpt.id == excerpt_id {
2784                return Some(excerpt);
2785            }
2786        }
2787        None
2788    }
2789
2790    pub fn remote_selections_in_range<'a>(
2791        &'a self,
2792        range: &'a Range<Anchor>,
2793    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
2794        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2795        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
2796        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
2797        cursor.seek(start_locator, Bias::Left, &());
2798        cursor
2799            .take_while(move |excerpt| excerpt.locator <= *end_locator)
2800            .flat_map(move |excerpt| {
2801                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
2802                if excerpt.id == range.start.excerpt_id {
2803                    query_range.start = range.start.text_anchor;
2804                }
2805                if excerpt.id == range.end.excerpt_id {
2806                    query_range.end = range.end.text_anchor;
2807                }
2808
2809                excerpt
2810                    .buffer
2811                    .remote_selections_in_range(query_range)
2812                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
2813                        selections.map(move |selection| {
2814                            let mut start = Anchor {
2815                                buffer_id: Some(excerpt.buffer_id),
2816                                excerpt_id: excerpt.id.clone(),
2817                                text_anchor: selection.start,
2818                            };
2819                            let mut end = Anchor {
2820                                buffer_id: Some(excerpt.buffer_id),
2821                                excerpt_id: excerpt.id.clone(),
2822                                text_anchor: selection.end,
2823                            };
2824                            if range.start.cmp(&start, self).is_gt() {
2825                                start = range.start.clone();
2826                            }
2827                            if range.end.cmp(&end, self).is_lt() {
2828                                end = range.end.clone();
2829                            }
2830
2831                            (
2832                                replica_id,
2833                                line_mode,
2834                                cursor_shape,
2835                                Selection {
2836                                    id: selection.id,
2837                                    start,
2838                                    end,
2839                                    reversed: selection.reversed,
2840                                    goal: selection.goal,
2841                                },
2842                            )
2843                        })
2844                    })
2845            })
2846    }
2847}
2848
2849#[cfg(any(test, feature = "test-support"))]
2850impl MultiBufferSnapshot {
2851    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
2852        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
2853        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
2854        start..end
2855    }
2856}
2857
2858impl History {
2859    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
2860        self.transaction_depth += 1;
2861        if self.transaction_depth == 1 {
2862            let id = self.next_transaction_id.tick();
2863            self.undo_stack.push(Transaction {
2864                id,
2865                buffer_transactions: Default::default(),
2866                first_edit_at: now,
2867                last_edit_at: now,
2868                suppress_grouping: false,
2869            });
2870            Some(id)
2871        } else {
2872            None
2873        }
2874    }
2875
2876    fn end_transaction(
2877        &mut self,
2878        now: Instant,
2879        buffer_transactions: HashMap<usize, TransactionId>,
2880    ) -> bool {
2881        assert_ne!(self.transaction_depth, 0);
2882        self.transaction_depth -= 1;
2883        if self.transaction_depth == 0 {
2884            if buffer_transactions.is_empty() {
2885                self.undo_stack.pop();
2886                false
2887            } else {
2888                self.redo_stack.clear();
2889                let transaction = self.undo_stack.last_mut().unwrap();
2890                transaction.last_edit_at = now;
2891                for (buffer_id, transaction_id) in buffer_transactions {
2892                    transaction
2893                        .buffer_transactions
2894                        .entry(buffer_id)
2895                        .or_insert(transaction_id);
2896                }
2897                true
2898            }
2899        } else {
2900            false
2901        }
2902    }
2903
2904    fn push_transaction<'a, T>(&mut self, buffer_transactions: T, now: Instant)
2905    where
2906        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
2907    {
2908        assert_eq!(self.transaction_depth, 0);
2909        let transaction = Transaction {
2910            id: self.next_transaction_id.tick(),
2911            buffer_transactions: buffer_transactions
2912                .into_iter()
2913                .map(|(buffer, transaction)| (buffer.id(), transaction.id))
2914                .collect(),
2915            first_edit_at: now,
2916            last_edit_at: now,
2917            suppress_grouping: false,
2918        };
2919        if !transaction.buffer_transactions.is_empty() {
2920            self.undo_stack.push(transaction);
2921            self.redo_stack.clear();
2922        }
2923    }
2924
2925    fn finalize_last_transaction(&mut self) {
2926        if let Some(transaction) = self.undo_stack.last_mut() {
2927            transaction.suppress_grouping = true;
2928        }
2929    }
2930
2931    fn pop_undo(&mut self) -> Option<&mut Transaction> {
2932        assert_eq!(self.transaction_depth, 0);
2933        if let Some(transaction) = self.undo_stack.pop() {
2934            self.redo_stack.push(transaction);
2935            self.redo_stack.last_mut()
2936        } else {
2937            None
2938        }
2939    }
2940
2941    fn pop_redo(&mut self) -> Option<&mut Transaction> {
2942        assert_eq!(self.transaction_depth, 0);
2943        if let Some(transaction) = self.redo_stack.pop() {
2944            self.undo_stack.push(transaction);
2945            self.undo_stack.last_mut()
2946        } else {
2947            None
2948        }
2949    }
2950
2951    fn group(&mut self) -> Option<TransactionId> {
2952        let mut count = 0;
2953        let mut transactions = self.undo_stack.iter();
2954        if let Some(mut transaction) = transactions.next_back() {
2955            while let Some(prev_transaction) = transactions.next_back() {
2956                if !prev_transaction.suppress_grouping
2957                    && transaction.first_edit_at - prev_transaction.last_edit_at
2958                        <= self.group_interval
2959                {
2960                    transaction = prev_transaction;
2961                    count += 1;
2962                } else {
2963                    break;
2964                }
2965            }
2966        }
2967        self.group_trailing(count)
2968    }
2969
2970    fn group_until(&mut self, transaction_id: TransactionId) {
2971        let mut count = 0;
2972        for transaction in self.undo_stack.iter().rev() {
2973            if transaction.id == transaction_id {
2974                self.group_trailing(count);
2975                break;
2976            } else if transaction.suppress_grouping {
2977                break;
2978            } else {
2979                count += 1;
2980            }
2981        }
2982    }
2983
2984    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
2985        let new_len = self.undo_stack.len() - n;
2986        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
2987        if let Some(last_transaction) = transactions_to_keep.last_mut() {
2988            if let Some(transaction) = transactions_to_merge.last() {
2989                last_transaction.last_edit_at = transaction.last_edit_at;
2990            }
2991            for to_merge in transactions_to_merge {
2992                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
2993                    last_transaction
2994                        .buffer_transactions
2995                        .entry(*buffer_id)
2996                        .or_insert(*transaction_id);
2997                }
2998            }
2999        }
3000
3001        self.undo_stack.truncate(new_len);
3002        self.undo_stack.last().map(|t| t.id)
3003    }
3004}
3005
3006impl Excerpt {
3007    fn new(
3008        id: ExcerptId,
3009        locator: Locator,
3010        buffer_id: usize,
3011        buffer: BufferSnapshot,
3012        range: ExcerptRange<text::Anchor>,
3013        has_trailing_newline: bool,
3014    ) -> Self {
3015        Excerpt {
3016            id,
3017            locator,
3018            max_buffer_row: range.context.end.to_point(&buffer).row,
3019            text_summary: buffer
3020                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
3021            buffer_id,
3022            buffer,
3023            range,
3024            has_trailing_newline,
3025        }
3026    }
3027
3028    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
3029        let content_start = self.range.context.start.to_offset(&self.buffer);
3030        let chunks_start = content_start + range.start;
3031        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
3032
3033        let footer_height = if self.has_trailing_newline
3034            && range.start <= self.text_summary.len
3035            && range.end > self.text_summary.len
3036        {
3037            1
3038        } else {
3039            0
3040        };
3041
3042        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
3043
3044        ExcerptChunks {
3045            content_chunks,
3046            footer_height,
3047        }
3048    }
3049
3050    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3051        let content_start = self.range.context.start.to_offset(&self.buffer);
3052        let bytes_start = content_start + range.start;
3053        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3054        let footer_height = if self.has_trailing_newline
3055            && range.start <= self.text_summary.len
3056            && range.end > self.text_summary.len
3057        {
3058            1
3059        } else {
3060            0
3061        };
3062        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
3063
3064        ExcerptBytes {
3065            content_bytes,
3066            footer_height,
3067        }
3068    }
3069
3070    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
3071        if text_anchor
3072            .cmp(&self.range.context.start, &self.buffer)
3073            .is_lt()
3074        {
3075            self.range.context.start
3076        } else if text_anchor
3077            .cmp(&self.range.context.end, &self.buffer)
3078            .is_gt()
3079        {
3080            self.range.context.end
3081        } else {
3082            text_anchor
3083        }
3084    }
3085
3086    fn contains(&self, anchor: &Anchor) -> bool {
3087        Some(self.buffer_id) == anchor.buffer_id
3088            && self
3089                .range
3090                .context
3091                .start
3092                .cmp(&anchor.text_anchor, &self.buffer)
3093                .is_le()
3094            && self
3095                .range
3096                .context
3097                .end
3098                .cmp(&anchor.text_anchor, &self.buffer)
3099                .is_ge()
3100    }
3101}
3102
3103impl ExcerptId {
3104    pub fn min() -> Self {
3105        Self(0)
3106    }
3107
3108    pub fn max() -> Self {
3109        Self(usize::MAX)
3110    }
3111
3112    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
3113        let a = snapshot.excerpt_locator_for_id(*self);
3114        let b = snapshot.excerpt_locator_for_id(*other);
3115        a.cmp(&b).then_with(|| self.0.cmp(&other.0))
3116    }
3117}
3118
3119impl Into<usize> for ExcerptId {
3120    fn into(self) -> usize {
3121        self.0
3122    }
3123}
3124
3125impl fmt::Debug for Excerpt {
3126    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3127        f.debug_struct("Excerpt")
3128            .field("id", &self.id)
3129            .field("locator", &self.locator)
3130            .field("buffer_id", &self.buffer_id)
3131            .field("range", &self.range)
3132            .field("text_summary", &self.text_summary)
3133            .field("has_trailing_newline", &self.has_trailing_newline)
3134            .finish()
3135    }
3136}
3137
3138impl sum_tree::Item for Excerpt {
3139    type Summary = ExcerptSummary;
3140
3141    fn summary(&self) -> Self::Summary {
3142        let mut text = self.text_summary.clone();
3143        if self.has_trailing_newline {
3144            text += TextSummary::from("\n");
3145        }
3146        ExcerptSummary {
3147            excerpt_id: self.id,
3148            excerpt_locator: self.locator.clone(),
3149            max_buffer_row: self.max_buffer_row,
3150            text,
3151        }
3152    }
3153}
3154
3155impl sum_tree::Item for ExcerptIdMapping {
3156    type Summary = ExcerptId;
3157
3158    fn summary(&self) -> Self::Summary {
3159        self.id
3160    }
3161}
3162
3163impl sum_tree::KeyedItem for ExcerptIdMapping {
3164    type Key = ExcerptId;
3165
3166    fn key(&self) -> Self::Key {
3167        self.id
3168    }
3169}
3170
3171impl sum_tree::Summary for ExcerptId {
3172    type Context = ();
3173
3174    fn add_summary(&mut self, other: &Self, _: &()) {
3175        *self = *other;
3176    }
3177}
3178
3179impl sum_tree::Summary for ExcerptSummary {
3180    type Context = ();
3181
3182    fn add_summary(&mut self, summary: &Self, _: &()) {
3183        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
3184        self.excerpt_locator = summary.excerpt_locator.clone();
3185        self.text.add_summary(&summary.text, &());
3186        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
3187    }
3188}
3189
3190impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
3191    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3192        *self += &summary.text;
3193    }
3194}
3195
3196impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
3197    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3198        *self += summary.text.len;
3199    }
3200}
3201
3202impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
3203    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3204        Ord::cmp(self, &cursor_location.text.len)
3205    }
3206}
3207
3208impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
3209    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
3210        Ord::cmp(&Some(self), cursor_location)
3211    }
3212}
3213
3214impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
3215    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3216        Ord::cmp(self, &cursor_location.excerpt_locator)
3217    }
3218}
3219
3220impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
3221    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3222        *self += summary.text.len_utf16;
3223    }
3224}
3225
3226impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
3227    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3228        *self += summary.text.lines;
3229    }
3230}
3231
3232impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
3233    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3234        *self += summary.text.lines_utf16()
3235    }
3236}
3237
3238impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
3239    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3240        *self = Some(&summary.excerpt_locator);
3241    }
3242}
3243
3244impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
3245    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3246        *self = Some(summary.excerpt_id);
3247    }
3248}
3249
3250impl<'a> MultiBufferRows<'a> {
3251    pub fn seek(&mut self, row: u32) {
3252        self.buffer_row_range = 0..0;
3253
3254        self.excerpts
3255            .seek_forward(&Point::new(row, 0), Bias::Right, &());
3256        if self.excerpts.item().is_none() {
3257            self.excerpts.prev(&());
3258
3259            if self.excerpts.item().is_none() && row == 0 {
3260                self.buffer_row_range = 0..1;
3261                return;
3262            }
3263        }
3264
3265        if let Some(excerpt) = self.excerpts.item() {
3266            let overshoot = row - self.excerpts.start().row;
3267            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3268            self.buffer_row_range.start = excerpt_start + overshoot;
3269            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
3270        }
3271    }
3272}
3273
3274impl<'a> Iterator for MultiBufferRows<'a> {
3275    type Item = Option<u32>;
3276
3277    fn next(&mut self) -> Option<Self::Item> {
3278        loop {
3279            if !self.buffer_row_range.is_empty() {
3280                let row = Some(self.buffer_row_range.start);
3281                self.buffer_row_range.start += 1;
3282                return Some(row);
3283            }
3284            self.excerpts.item()?;
3285            self.excerpts.next(&());
3286            let excerpt = self.excerpts.item()?;
3287            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3288            self.buffer_row_range.end =
3289                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
3290        }
3291    }
3292}
3293
3294impl<'a> MultiBufferChunks<'a> {
3295    pub fn offset(&self) -> usize {
3296        self.range.start
3297    }
3298
3299    pub fn seek(&mut self, offset: usize) {
3300        self.range.start = offset;
3301        self.excerpts.seek(&offset, Bias::Right, &());
3302        if let Some(excerpt) = self.excerpts.item() {
3303            self.excerpt_chunks = Some(excerpt.chunks_in_range(
3304                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
3305                self.language_aware,
3306            ));
3307        } else {
3308            self.excerpt_chunks = None;
3309        }
3310    }
3311}
3312
3313impl<'a> Iterator for MultiBufferChunks<'a> {
3314    type Item = Chunk<'a>;
3315
3316    fn next(&mut self) -> Option<Self::Item> {
3317        if self.range.is_empty() {
3318            None
3319        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
3320            self.range.start += chunk.text.len();
3321            Some(chunk)
3322        } else {
3323            self.excerpts.next(&());
3324            let excerpt = self.excerpts.item()?;
3325            self.excerpt_chunks = Some(excerpt.chunks_in_range(
3326                0..self.range.end - self.excerpts.start(),
3327                self.language_aware,
3328            ));
3329            self.next()
3330        }
3331    }
3332}
3333
3334impl<'a> MultiBufferBytes<'a> {
3335    fn consume(&mut self, len: usize) {
3336        self.range.start += len;
3337        self.chunk = &self.chunk[len..];
3338
3339        if !self.range.is_empty() && self.chunk.is_empty() {
3340            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
3341                self.chunk = chunk;
3342            } else {
3343                self.excerpts.next(&());
3344                if let Some(excerpt) = self.excerpts.item() {
3345                    let mut excerpt_bytes =
3346                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
3347                    self.chunk = excerpt_bytes.next().unwrap();
3348                    self.excerpt_bytes = Some(excerpt_bytes);
3349                }
3350            }
3351        }
3352    }
3353}
3354
3355impl<'a> Iterator for MultiBufferBytes<'a> {
3356    type Item = &'a [u8];
3357
3358    fn next(&mut self) -> Option<Self::Item> {
3359        let chunk = self.chunk;
3360        if chunk.is_empty() {
3361            None
3362        } else {
3363            self.consume(chunk.len());
3364            Some(chunk)
3365        }
3366    }
3367}
3368
3369impl<'a> io::Read for MultiBufferBytes<'a> {
3370    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
3371        let len = cmp::min(buf.len(), self.chunk.len());
3372        buf[..len].copy_from_slice(&self.chunk[..len]);
3373        if len > 0 {
3374            self.consume(len);
3375        }
3376        Ok(len)
3377    }
3378}
3379
3380impl<'a> Iterator for ExcerptBytes<'a> {
3381    type Item = &'a [u8];
3382
3383    fn next(&mut self) -> Option<Self::Item> {
3384        if let Some(chunk) = self.content_bytes.next() {
3385            if !chunk.is_empty() {
3386                return Some(chunk);
3387            }
3388        }
3389
3390        if self.footer_height > 0 {
3391            let result = &NEWLINES[..self.footer_height];
3392            self.footer_height = 0;
3393            return Some(result);
3394        }
3395
3396        None
3397    }
3398}
3399
3400impl<'a> Iterator for ExcerptChunks<'a> {
3401    type Item = Chunk<'a>;
3402
3403    fn next(&mut self) -> Option<Self::Item> {
3404        if let Some(chunk) = self.content_chunks.next() {
3405            return Some(chunk);
3406        }
3407
3408        if self.footer_height > 0 {
3409            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
3410            self.footer_height = 0;
3411            return Some(Chunk {
3412                text,
3413                ..Default::default()
3414            });
3415        }
3416
3417        None
3418    }
3419}
3420
3421impl ToOffset for Point {
3422    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3423        snapshot.point_to_offset(*self)
3424    }
3425}
3426
3427impl ToOffset for usize {
3428    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3429        assert!(*self <= snapshot.len(), "offset is out of range");
3430        *self
3431    }
3432}
3433
3434impl ToOffset for OffsetUtf16 {
3435    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3436        snapshot.offset_utf16_to_offset(*self)
3437    }
3438}
3439
3440impl ToOffset for PointUtf16 {
3441    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3442        snapshot.point_utf16_to_offset(*self)
3443    }
3444}
3445
3446impl ToOffsetUtf16 for OffsetUtf16 {
3447    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
3448        *self
3449    }
3450}
3451
3452impl ToOffsetUtf16 for usize {
3453    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
3454        snapshot.offset_to_offset_utf16(*self)
3455    }
3456}
3457
3458impl ToPoint for usize {
3459    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
3460        snapshot.offset_to_point(*self)
3461    }
3462}
3463
3464impl ToPoint for Point {
3465    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
3466        *self
3467    }
3468}
3469
3470impl ToPointUtf16 for usize {
3471    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
3472        snapshot.offset_to_point_utf16(*self)
3473    }
3474}
3475
3476impl ToPointUtf16 for Point {
3477    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
3478        snapshot.point_to_point_utf16(*self)
3479    }
3480}
3481
3482impl ToPointUtf16 for PointUtf16 {
3483    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
3484        *self
3485    }
3486}
3487
3488#[cfg(test)]
3489mod tests {
3490    use super::*;
3491    use gpui::MutableAppContext;
3492    use language::{Buffer, Rope};
3493    use rand::prelude::*;
3494    use settings::Settings;
3495    use std::{env, rc::Rc};
3496
3497    use util::test::sample_text;
3498
3499    #[gpui::test]
3500    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
3501        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
3502        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3503
3504        let snapshot = multibuffer.read(cx).snapshot(cx);
3505        assert_eq!(snapshot.text(), buffer.read(cx).text());
3506
3507        assert_eq!(
3508            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3509            (0..buffer.read(cx).row_count())
3510                .map(Some)
3511                .collect::<Vec<_>>()
3512        );
3513
3514        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
3515        let snapshot = multibuffer.read(cx).snapshot(cx);
3516
3517        assert_eq!(snapshot.text(), buffer.read(cx).text());
3518        assert_eq!(
3519            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3520            (0..buffer.read(cx).row_count())
3521                .map(Some)
3522                .collect::<Vec<_>>()
3523        );
3524    }
3525
3526    #[gpui::test]
3527    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
3528        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
3529        let guest_buffer = cx.add_model(|cx| {
3530            let state = host_buffer.read(cx).to_proto();
3531            let ops = cx
3532                .background()
3533                .block(host_buffer.read(cx).serialize_ops(cx));
3534            let mut buffer = Buffer::from_proto(1, state, None).unwrap();
3535            buffer
3536                .apply_ops(
3537                    ops.into_iter()
3538                        .map(|op| language::proto::deserialize_operation(op).unwrap()),
3539                    cx,
3540                )
3541                .unwrap();
3542            buffer
3543        });
3544        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
3545        let snapshot = multibuffer.read(cx).snapshot(cx);
3546        assert_eq!(snapshot.text(), "a");
3547
3548        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
3549        let snapshot = multibuffer.read(cx).snapshot(cx);
3550        assert_eq!(snapshot.text(), "ab");
3551
3552        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
3553        let snapshot = multibuffer.read(cx).snapshot(cx);
3554        assert_eq!(snapshot.text(), "abc");
3555    }
3556
3557    #[gpui::test]
3558    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
3559        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
3560        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
3561        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3562
3563        let events = Rc::new(RefCell::new(Vec::<Event>::new()));
3564        multibuffer.update(cx, |_, cx| {
3565            let events = events.clone();
3566            cx.subscribe(&multibuffer, move |_, _, event, _| {
3567                events.borrow_mut().push(event.clone())
3568            })
3569            .detach();
3570        });
3571
3572        let subscription = multibuffer.update(cx, |multibuffer, cx| {
3573            let subscription = multibuffer.subscribe();
3574            multibuffer.push_excerpts(
3575                buffer_1.clone(),
3576                [ExcerptRange {
3577                    context: Point::new(1, 2)..Point::new(2, 5),
3578                    primary: None,
3579                }],
3580                cx,
3581            );
3582            assert_eq!(
3583                subscription.consume().into_inner(),
3584                [Edit {
3585                    old: 0..0,
3586                    new: 0..10
3587                }]
3588            );
3589
3590            multibuffer.push_excerpts(
3591                buffer_1.clone(),
3592                [ExcerptRange {
3593                    context: Point::new(3, 3)..Point::new(4, 4),
3594                    primary: None,
3595                }],
3596                cx,
3597            );
3598            multibuffer.push_excerpts(
3599                buffer_2.clone(),
3600                [ExcerptRange {
3601                    context: Point::new(3, 1)..Point::new(3, 3),
3602                    primary: None,
3603                }],
3604                cx,
3605            );
3606            assert_eq!(
3607                subscription.consume().into_inner(),
3608                [Edit {
3609                    old: 10..10,
3610                    new: 10..22
3611                }]
3612            );
3613
3614            subscription
3615        });
3616
3617        // Adding excerpts emits an edited event.
3618        assert_eq!(
3619            events.borrow().as_slice(),
3620            &[Event::Edited, Event::Edited, Event::Edited]
3621        );
3622
3623        let snapshot = multibuffer.read(cx).snapshot(cx);
3624        assert_eq!(
3625            snapshot.text(),
3626            concat!(
3627                "bbbb\n",  // Preserve newlines
3628                "ccccc\n", //
3629                "ddd\n",   //
3630                "eeee\n",  //
3631                "jj"       //
3632            )
3633        );
3634        assert_eq!(
3635            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3636            [Some(1), Some(2), Some(3), Some(4), Some(3)]
3637        );
3638        assert_eq!(
3639            snapshot.buffer_rows(2).collect::<Vec<_>>(),
3640            [Some(3), Some(4), Some(3)]
3641        );
3642        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
3643        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
3644
3645        assert_eq!(
3646            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
3647            &[
3648                (0, "bbbb\nccccc".to_string(), true),
3649                (2, "ddd\neeee".to_string(), false),
3650                (4, "jj".to_string(), true),
3651            ]
3652        );
3653        assert_eq!(
3654            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
3655            &[(0, "bbbb\nccccc".to_string(), true)]
3656        );
3657        assert_eq!(
3658            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
3659            &[]
3660        );
3661        assert_eq!(
3662            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
3663            &[]
3664        );
3665        assert_eq!(
3666            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3667            &[(2, "ddd\neeee".to_string(), false)]
3668        );
3669        assert_eq!(
3670            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3671            &[(2, "ddd\neeee".to_string(), false)]
3672        );
3673        assert_eq!(
3674            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
3675            &[(2, "ddd\neeee".to_string(), false)]
3676        );
3677        assert_eq!(
3678            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
3679            &[(4, "jj".to_string(), true)]
3680        );
3681        assert_eq!(
3682            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
3683            &[]
3684        );
3685
3686        buffer_1.update(cx, |buffer, cx| {
3687            let text = "\n";
3688            buffer.edit(
3689                [
3690                    (Point::new(0, 0)..Point::new(0, 0), text),
3691                    (Point::new(2, 1)..Point::new(2, 3), text),
3692                ],
3693                None,
3694                cx,
3695            );
3696        });
3697
3698        let snapshot = multibuffer.read(cx).snapshot(cx);
3699        assert_eq!(
3700            snapshot.text(),
3701            concat!(
3702                "bbbb\n", // Preserve newlines
3703                "c\n",    //
3704                "cc\n",   //
3705                "ddd\n",  //
3706                "eeee\n", //
3707                "jj"      //
3708            )
3709        );
3710
3711        assert_eq!(
3712            subscription.consume().into_inner(),
3713            [Edit {
3714                old: 6..8,
3715                new: 6..7
3716            }]
3717        );
3718
3719        let snapshot = multibuffer.read(cx).snapshot(cx);
3720        assert_eq!(
3721            snapshot.clip_point(Point::new(0, 5), Bias::Left),
3722            Point::new(0, 4)
3723        );
3724        assert_eq!(
3725            snapshot.clip_point(Point::new(0, 5), Bias::Right),
3726            Point::new(0, 4)
3727        );
3728        assert_eq!(
3729            snapshot.clip_point(Point::new(5, 1), Bias::Right),
3730            Point::new(5, 1)
3731        );
3732        assert_eq!(
3733            snapshot.clip_point(Point::new(5, 2), Bias::Right),
3734            Point::new(5, 2)
3735        );
3736        assert_eq!(
3737            snapshot.clip_point(Point::new(5, 3), Bias::Right),
3738            Point::new(5, 2)
3739        );
3740
3741        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
3742            let (buffer_2_excerpt_id, _) =
3743                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
3744            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
3745            multibuffer.snapshot(cx)
3746        });
3747
3748        assert_eq!(
3749            snapshot.text(),
3750            concat!(
3751                "bbbb\n", // Preserve newlines
3752                "c\n",    //
3753                "cc\n",   //
3754                "ddd\n",  //
3755                "eeee",   //
3756            )
3757        );
3758
3759        fn boundaries_in_range(
3760            range: Range<Point>,
3761            snapshot: &MultiBufferSnapshot,
3762        ) -> Vec<(u32, String, bool)> {
3763            snapshot
3764                .excerpt_boundaries_in_range(range)
3765                .map(|boundary| {
3766                    (
3767                        boundary.row,
3768                        boundary
3769                            .buffer
3770                            .text_for_range(boundary.range.context)
3771                            .collect::<String>(),
3772                        boundary.starts_new_buffer,
3773                    )
3774                })
3775                .collect::<Vec<_>>()
3776        }
3777    }
3778
3779    #[gpui::test]
3780    fn test_excerpts_with_context_lines(cx: &mut MutableAppContext) {
3781        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
3782        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3783        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
3784            multibuffer.push_excerpts_with_context_lines(
3785                buffer.clone(),
3786                vec![
3787                    Point::new(3, 2)..Point::new(4, 2),
3788                    Point::new(7, 1)..Point::new(7, 3),
3789                    Point::new(15, 0)..Point::new(15, 0),
3790                ],
3791                2,
3792                cx,
3793            )
3794        });
3795
3796        let snapshot = multibuffer.read(cx).snapshot(cx);
3797        assert_eq!(
3798            snapshot.text(),
3799            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
3800        );
3801
3802        assert_eq!(
3803            anchor_ranges
3804                .iter()
3805                .map(|range| range.to_point(&snapshot))
3806                .collect::<Vec<_>>(),
3807            vec![
3808                Point::new(2, 2)..Point::new(3, 2),
3809                Point::new(6, 1)..Point::new(6, 3),
3810                Point::new(12, 0)..Point::new(12, 0)
3811            ]
3812        );
3813    }
3814
3815    #[gpui::test]
3816    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
3817        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3818
3819        let snapshot = multibuffer.read(cx).snapshot(cx);
3820        assert_eq!(snapshot.text(), "");
3821        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
3822        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
3823    }
3824
3825    #[gpui::test]
3826    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
3827        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3828        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3829        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3830        buffer.update(cx, |buffer, cx| {
3831            buffer.edit([(0..0, "X")], None, cx);
3832            buffer.edit([(5..5, "Y")], None, cx);
3833        });
3834        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3835
3836        assert_eq!(old_snapshot.text(), "abcd");
3837        assert_eq!(new_snapshot.text(), "XabcdY");
3838
3839        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3840        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3841        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
3842        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
3843    }
3844
3845    #[gpui::test]
3846    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
3847        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3848        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
3849        let multibuffer = cx.add_model(|cx| {
3850            let mut multibuffer = MultiBuffer::new(0);
3851            multibuffer.push_excerpts(
3852                buffer_1.clone(),
3853                [ExcerptRange {
3854                    context: 0..4,
3855                    primary: None,
3856                }],
3857                cx,
3858            );
3859            multibuffer.push_excerpts(
3860                buffer_2.clone(),
3861                [ExcerptRange {
3862                    context: 0..5,
3863                    primary: None,
3864                }],
3865                cx,
3866            );
3867            multibuffer
3868        });
3869        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3870
3871        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
3872        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
3873        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3874        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3875        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3876        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3877
3878        buffer_1.update(cx, |buffer, cx| {
3879            buffer.edit([(0..0, "W")], None, cx);
3880            buffer.edit([(5..5, "X")], None, cx);
3881        });
3882        buffer_2.update(cx, |buffer, cx| {
3883            buffer.edit([(0..0, "Y")], None, cx);
3884            buffer.edit([(6..6, "Z")], None, cx);
3885        });
3886        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3887
3888        assert_eq!(old_snapshot.text(), "abcd\nefghi");
3889        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
3890
3891        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3892        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3893        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
3894        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
3895        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
3896        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
3897        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
3898        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
3899        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
3900        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
3901    }
3902
3903    #[gpui::test]
3904    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
3905        cx: &mut MutableAppContext,
3906    ) {
3907        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3908        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
3909        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3910
3911        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
3912        // Add an excerpt from buffer 1 that spans this new insertion.
3913        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
3914        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
3915            multibuffer
3916                .push_excerpts(
3917                    buffer_1.clone(),
3918                    [ExcerptRange {
3919                        context: 0..7,
3920                        primary: None,
3921                    }],
3922                    cx,
3923                )
3924                .pop()
3925                .unwrap()
3926        });
3927
3928        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
3929        assert_eq!(snapshot_1.text(), "abcd123");
3930
3931        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
3932        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
3933            multibuffer.remove_excerpts([excerpt_id_1], cx);
3934            let mut ids = multibuffer
3935                .push_excerpts(
3936                    buffer_2.clone(),
3937                    [
3938                        ExcerptRange {
3939                            context: 0..4,
3940                            primary: None,
3941                        },
3942                        ExcerptRange {
3943                            context: 6..10,
3944                            primary: None,
3945                        },
3946                        ExcerptRange {
3947                            context: 12..16,
3948                            primary: None,
3949                        },
3950                    ],
3951                    cx,
3952                )
3953                .into_iter();
3954            (ids.next().unwrap(), ids.next().unwrap())
3955        });
3956        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
3957        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
3958
3959        // The old excerpt id doesn't get reused.
3960        assert_ne!(excerpt_id_2, excerpt_id_1);
3961
3962        // Resolve some anchors from the previous snapshot in the new snapshot.
3963        // The current excerpts are from a different buffer, so we don't attempt to
3964        // resolve the old text anchor in the new buffer.
3965        assert_eq!(
3966            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
3967            0
3968        );
3969        assert_eq!(
3970            snapshot_2.summaries_for_anchors::<usize, _>(&[
3971                snapshot_1.anchor_before(2),
3972                snapshot_1.anchor_after(3)
3973            ]),
3974            vec![0, 0]
3975        );
3976
3977        // Refresh anchors from the old snapshot. The return value indicates that both
3978        // anchors lost their original excerpt.
3979        let refresh =
3980            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
3981        assert_eq!(
3982            refresh,
3983            &[
3984                (0, snapshot_2.anchor_before(0), false),
3985                (1, snapshot_2.anchor_after(0), false),
3986            ]
3987        );
3988
3989        // Replace the middle excerpt with a smaller excerpt in buffer 2,
3990        // that intersects the old excerpt.
3991        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
3992            multibuffer.remove_excerpts([excerpt_id_3], cx);
3993            multibuffer
3994                .insert_excerpts_after(
3995                    excerpt_id_2,
3996                    buffer_2.clone(),
3997                    [ExcerptRange {
3998                        context: 5..8,
3999                        primary: None,
4000                    }],
4001                    cx,
4002                )
4003                .pop()
4004                .unwrap()
4005        });
4006
4007        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
4008        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
4009        assert_ne!(excerpt_id_5, excerpt_id_3);
4010
4011        // Resolve some anchors from the previous snapshot in the new snapshot.
4012        // The third anchor can't be resolved, since its excerpt has been removed,
4013        // so it resolves to the same position as its predecessor.
4014        let anchors = [
4015            snapshot_2.anchor_before(0),
4016            snapshot_2.anchor_after(2),
4017            snapshot_2.anchor_after(6),
4018            snapshot_2.anchor_after(14),
4019        ];
4020        assert_eq!(
4021            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
4022            &[0, 2, 9, 13]
4023        );
4024
4025        let new_anchors = snapshot_3.refresh_anchors(&anchors);
4026        assert_eq!(
4027            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
4028            &[(0, true), (1, true), (2, true), (3, true)]
4029        );
4030        assert_eq!(
4031            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
4032            &[0, 2, 7, 13]
4033        );
4034    }
4035
4036    #[gpui::test(iterations = 100)]
4037    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
4038        let operations = env::var("OPERATIONS")
4039            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
4040            .unwrap_or(10);
4041
4042        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
4043        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4044        let mut excerpt_ids = Vec::<ExcerptId>::new();
4045        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
4046        let mut anchors = Vec::new();
4047        let mut old_versions = Vec::new();
4048
4049        for _ in 0..operations {
4050            match rng.gen_range(0..100) {
4051                0..=19 if !buffers.is_empty() => {
4052                    let buffer = buffers.choose(&mut rng).unwrap();
4053                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
4054                }
4055                20..=29 if !expected_excerpts.is_empty() => {
4056                    let mut ids_to_remove = vec![];
4057                    for _ in 0..rng.gen_range(1..=3) {
4058                        if expected_excerpts.is_empty() {
4059                            break;
4060                        }
4061
4062                        let ix = rng.gen_range(0..expected_excerpts.len());
4063                        ids_to_remove.push(excerpt_ids.remove(ix));
4064                        let (buffer, range) = expected_excerpts.remove(ix);
4065                        let buffer = buffer.read(cx);
4066                        log::info!(
4067                            "Removing excerpt {}: {:?}",
4068                            ix,
4069                            buffer
4070                                .text_for_range(range.to_offset(buffer))
4071                                .collect::<String>(),
4072                        );
4073                    }
4074                    let snapshot = multibuffer.read(cx).read(cx);
4075                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(&b, &snapshot));
4076                    drop(snapshot);
4077                    multibuffer.update(cx, |multibuffer, cx| {
4078                        multibuffer.remove_excerpts(ids_to_remove, cx)
4079                    });
4080                }
4081                30..=39 if !expected_excerpts.is_empty() => {
4082                    let multibuffer = multibuffer.read(cx).read(cx);
4083                    let offset =
4084                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
4085                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
4086                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
4087                    anchors.push(multibuffer.anchor_at(offset, bias));
4088                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
4089                }
4090                40..=44 if !anchors.is_empty() => {
4091                    let multibuffer = multibuffer.read(cx).read(cx);
4092                    let prev_len = anchors.len();
4093                    anchors = multibuffer
4094                        .refresh_anchors(&anchors)
4095                        .into_iter()
4096                        .map(|a| a.1)
4097                        .collect();
4098
4099                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
4100                    // overshoot its boundaries.
4101                    assert_eq!(anchors.len(), prev_len);
4102                    for anchor in &anchors {
4103                        if anchor.excerpt_id == ExcerptId::min()
4104                            || anchor.excerpt_id == ExcerptId::max()
4105                        {
4106                            continue;
4107                        }
4108
4109                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
4110                        assert_eq!(excerpt.id, anchor.excerpt_id);
4111                        assert!(excerpt.contains(anchor));
4112                    }
4113                }
4114                _ => {
4115                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
4116                        let base_text = util::RandomCharIter::new(&mut rng)
4117                            .take(10)
4118                            .collect::<String>();
4119                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
4120                        buffers.last().unwrap()
4121                    } else {
4122                        buffers.choose(&mut rng).unwrap()
4123                    };
4124
4125                    let buffer = buffer_handle.read(cx);
4126                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
4127                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
4128                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
4129                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
4130                    let prev_excerpt_id = excerpt_ids
4131                        .get(prev_excerpt_ix)
4132                        .cloned()
4133                        .unwrap_or_else(ExcerptId::max);
4134                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
4135
4136                    log::info!(
4137                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
4138                        excerpt_ix,
4139                        expected_excerpts.len(),
4140                        buffer_handle.id(),
4141                        buffer.text(),
4142                        start_ix..end_ix,
4143                        &buffer.text()[start_ix..end_ix]
4144                    );
4145
4146                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
4147                        multibuffer
4148                            .insert_excerpts_after(
4149                                prev_excerpt_id,
4150                                buffer_handle.clone(),
4151                                [ExcerptRange {
4152                                    context: start_ix..end_ix,
4153                                    primary: None,
4154                                }],
4155                                cx,
4156                            )
4157                            .pop()
4158                            .unwrap()
4159                    });
4160
4161                    excerpt_ids.insert(excerpt_ix, excerpt_id);
4162                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
4163                }
4164            }
4165
4166            if rng.gen_bool(0.3) {
4167                multibuffer.update(cx, |multibuffer, cx| {
4168                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
4169                })
4170            }
4171
4172            let snapshot = multibuffer.read(cx).snapshot(cx);
4173
4174            let mut excerpt_starts = Vec::new();
4175            let mut expected_text = String::new();
4176            let mut expected_buffer_rows = Vec::new();
4177            for (buffer, range) in &expected_excerpts {
4178                let buffer = buffer.read(cx);
4179                let buffer_range = range.to_offset(buffer);
4180
4181                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
4182                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
4183                expected_text.push('\n');
4184
4185                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
4186                    ..=buffer.offset_to_point(buffer_range.end).row;
4187                for row in buffer_row_range {
4188                    expected_buffer_rows.push(Some(row));
4189                }
4190            }
4191            // Remove final trailing newline.
4192            if !expected_excerpts.is_empty() {
4193                expected_text.pop();
4194            }
4195
4196            // Always report one buffer row
4197            if expected_buffer_rows.is_empty() {
4198                expected_buffer_rows.push(Some(0));
4199            }
4200
4201            assert_eq!(snapshot.text(), expected_text);
4202            log::info!("MultiBuffer text: {:?}", expected_text);
4203
4204            assert_eq!(
4205                snapshot.buffer_rows(0).collect::<Vec<_>>(),
4206                expected_buffer_rows,
4207            );
4208
4209            for _ in 0..5 {
4210                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
4211                assert_eq!(
4212                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
4213                    &expected_buffer_rows[start_row..],
4214                    "buffer_rows({})",
4215                    start_row
4216                );
4217            }
4218
4219            assert_eq!(
4220                snapshot.max_buffer_row(),
4221                expected_buffer_rows.into_iter().flatten().max().unwrap()
4222            );
4223
4224            let mut excerpt_starts = excerpt_starts.into_iter();
4225            for (buffer, range) in &expected_excerpts {
4226                let buffer_id = buffer.id();
4227                let buffer = buffer.read(cx);
4228                let buffer_range = range.to_offset(buffer);
4229                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
4230                let buffer_start_point_utf16 =
4231                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
4232
4233                let excerpt_start = excerpt_starts.next().unwrap();
4234                let mut offset = excerpt_start.len;
4235                let mut buffer_offset = buffer_range.start;
4236                let mut point = excerpt_start.lines;
4237                let mut buffer_point = buffer_start_point;
4238                let mut point_utf16 = excerpt_start.lines_utf16();
4239                let mut buffer_point_utf16 = buffer_start_point_utf16;
4240                for ch in buffer
4241                    .snapshot()
4242                    .chunks(buffer_range.clone(), false)
4243                    .flat_map(|c| c.text.chars())
4244                {
4245                    for _ in 0..ch.len_utf8() {
4246                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
4247                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
4248                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
4249                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
4250                        assert_eq!(
4251                            left_offset,
4252                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
4253                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
4254                            offset,
4255                            buffer_id,
4256                            buffer_offset,
4257                        );
4258                        assert_eq!(
4259                            right_offset,
4260                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
4261                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
4262                            offset,
4263                            buffer_id,
4264                            buffer_offset,
4265                        );
4266
4267                        let left_point = snapshot.clip_point(point, Bias::Left);
4268                        let right_point = snapshot.clip_point(point, Bias::Right);
4269                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
4270                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
4271                        assert_eq!(
4272                            left_point,
4273                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
4274                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
4275                            point,
4276                            buffer_id,
4277                            buffer_point,
4278                        );
4279                        assert_eq!(
4280                            right_point,
4281                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
4282                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
4283                            point,
4284                            buffer_id,
4285                            buffer_point,
4286                        );
4287
4288                        assert_eq!(
4289                            snapshot.point_to_offset(left_point),
4290                            left_offset,
4291                            "point_to_offset({:?})",
4292                            left_point,
4293                        );
4294                        assert_eq!(
4295                            snapshot.offset_to_point(left_offset),
4296                            left_point,
4297                            "offset_to_point({:?})",
4298                            left_offset,
4299                        );
4300
4301                        offset += 1;
4302                        buffer_offset += 1;
4303                        if ch == '\n' {
4304                            point += Point::new(1, 0);
4305                            buffer_point += Point::new(1, 0);
4306                        } else {
4307                            point += Point::new(0, 1);
4308                            buffer_point += Point::new(0, 1);
4309                        }
4310                    }
4311
4312                    for _ in 0..ch.len_utf16() {
4313                        let left_point_utf16 =
4314                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
4315                        let right_point_utf16 =
4316                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
4317                        let buffer_left_point_utf16 =
4318                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
4319                        let buffer_right_point_utf16 =
4320                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
4321                        assert_eq!(
4322                            left_point_utf16,
4323                            excerpt_start.lines_utf16()
4324                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
4325                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
4326                            point_utf16,
4327                            buffer_id,
4328                            buffer_point_utf16,
4329                        );
4330                        assert_eq!(
4331                            right_point_utf16,
4332                            excerpt_start.lines_utf16()
4333                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
4334                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
4335                            point_utf16,
4336                            buffer_id,
4337                            buffer_point_utf16,
4338                        );
4339
4340                        if ch == '\n' {
4341                            point_utf16 += PointUtf16::new(1, 0);
4342                            buffer_point_utf16 += PointUtf16::new(1, 0);
4343                        } else {
4344                            point_utf16 += PointUtf16::new(0, 1);
4345                            buffer_point_utf16 += PointUtf16::new(0, 1);
4346                        }
4347                    }
4348                }
4349            }
4350
4351            for (row, line) in expected_text.split('\n').enumerate() {
4352                assert_eq!(
4353                    snapshot.line_len(row as u32),
4354                    line.len() as u32,
4355                    "line_len({}).",
4356                    row
4357                );
4358            }
4359
4360            let text_rope = Rope::from(expected_text.as_str());
4361            for _ in 0..10 {
4362                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
4363                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
4364
4365                let text_for_range = snapshot
4366                    .text_for_range(start_ix..end_ix)
4367                    .collect::<String>();
4368                assert_eq!(
4369                    text_for_range,
4370                    &expected_text[start_ix..end_ix],
4371                    "incorrect text for range {:?}",
4372                    start_ix..end_ix
4373                );
4374
4375                let excerpted_buffer_ranges = multibuffer
4376                    .read(cx)
4377                    .range_to_buffer_ranges(start_ix..end_ix, cx);
4378                let excerpted_buffers_text = excerpted_buffer_ranges
4379                    .into_iter()
4380                    .map(|(buffer, buffer_range)| {
4381                        buffer
4382                            .read(cx)
4383                            .text_for_range(buffer_range)
4384                            .collect::<String>()
4385                    })
4386                    .collect::<Vec<_>>()
4387                    .join("\n");
4388                assert_eq!(excerpted_buffers_text, text_for_range);
4389
4390                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
4391                assert_eq!(
4392                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
4393                    expected_summary,
4394                    "incorrect summary for range {:?}",
4395                    start_ix..end_ix
4396                );
4397            }
4398
4399            // Anchor resolution
4400            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
4401            assert_eq!(anchors.len(), summaries.len());
4402            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
4403                assert!(resolved_offset <= snapshot.len());
4404                assert_eq!(
4405                    snapshot.summary_for_anchor::<usize>(anchor),
4406                    resolved_offset
4407                );
4408            }
4409
4410            for _ in 0..10 {
4411                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
4412                assert_eq!(
4413                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
4414                    expected_text[..end_ix].chars().rev().collect::<String>(),
4415                );
4416            }
4417
4418            for _ in 0..10 {
4419                let end_ix = rng.gen_range(0..=text_rope.len());
4420                let start_ix = rng.gen_range(0..=end_ix);
4421                assert_eq!(
4422                    snapshot
4423                        .bytes_in_range(start_ix..end_ix)
4424                        .flatten()
4425                        .copied()
4426                        .collect::<Vec<_>>(),
4427                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
4428                    "bytes_in_range({:?})",
4429                    start_ix..end_ix,
4430                );
4431            }
4432        }
4433
4434        let snapshot = multibuffer.read(cx).snapshot(cx);
4435        for (old_snapshot, subscription) in old_versions {
4436            let edits = subscription.consume().into_inner();
4437
4438            log::info!(
4439                "applying subscription edits to old text: {:?}: {:?}",
4440                old_snapshot.text(),
4441                edits,
4442            );
4443
4444            let mut text = old_snapshot.text();
4445            for edit in edits {
4446                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
4447                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
4448            }
4449            assert_eq!(text.to_string(), snapshot.text());
4450        }
4451    }
4452
4453    #[gpui::test]
4454    fn test_history(cx: &mut MutableAppContext) {
4455        cx.set_global(Settings::test(cx));
4456        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
4457        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
4458        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4459        let group_interval = multibuffer.read(cx).history.group_interval;
4460        multibuffer.update(cx, |multibuffer, cx| {
4461            multibuffer.push_excerpts(
4462                buffer_1.clone(),
4463                [ExcerptRange {
4464                    context: 0..buffer_1.read(cx).len(),
4465                    primary: None,
4466                }],
4467                cx,
4468            );
4469            multibuffer.push_excerpts(
4470                buffer_2.clone(),
4471                [ExcerptRange {
4472                    context: 0..buffer_2.read(cx).len(),
4473                    primary: None,
4474                }],
4475                cx,
4476            );
4477        });
4478
4479        let mut now = Instant::now();
4480
4481        multibuffer.update(cx, |multibuffer, cx| {
4482            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
4483            multibuffer.edit(
4484                [
4485                    (Point::new(0, 0)..Point::new(0, 0), "A"),
4486                    (Point::new(1, 0)..Point::new(1, 0), "A"),
4487                ],
4488                None,
4489                cx,
4490            );
4491            multibuffer.edit(
4492                [
4493                    (Point::new(0, 1)..Point::new(0, 1), "B"),
4494                    (Point::new(1, 1)..Point::new(1, 1), "B"),
4495                ],
4496                None,
4497                cx,
4498            );
4499            multibuffer.end_transaction_at(now, cx);
4500            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
4501
4502            // Edit buffer 1 through the multibuffer
4503            now += 2 * group_interval;
4504            multibuffer.start_transaction_at(now, cx);
4505            multibuffer.edit([(2..2, "C")], None, cx);
4506            multibuffer.end_transaction_at(now, cx);
4507            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
4508
4509            // Edit buffer 1 independently
4510            buffer_1.update(cx, |buffer_1, cx| {
4511                buffer_1.start_transaction_at(now);
4512                buffer_1.edit([(3..3, "D")], None, cx);
4513                buffer_1.end_transaction_at(now, cx);
4514
4515                now += 2 * group_interval;
4516                buffer_1.start_transaction_at(now);
4517                buffer_1.edit([(4..4, "E")], None, cx);
4518                buffer_1.end_transaction_at(now, cx);
4519            });
4520            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
4521
4522            // An undo in the multibuffer undoes the multibuffer transaction
4523            // and also any individual buffer edits that have occured since
4524            // that transaction.
4525            multibuffer.undo(cx);
4526            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
4527
4528            multibuffer.undo(cx);
4529            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
4530
4531            multibuffer.redo(cx);
4532            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
4533
4534            multibuffer.redo(cx);
4535            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
4536
4537            // Undo buffer 2 independently.
4538            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
4539            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
4540
4541            // An undo in the multibuffer undoes the components of the
4542            // the last multibuffer transaction that are not already undone.
4543            multibuffer.undo(cx);
4544            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
4545
4546            multibuffer.undo(cx);
4547            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
4548
4549            multibuffer.redo(cx);
4550            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
4551
4552            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
4553            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
4554
4555            // Redo stack gets cleared after an edit.
4556            now += 2 * group_interval;
4557            multibuffer.start_transaction_at(now, cx);
4558            multibuffer.edit([(0..0, "X")], None, cx);
4559            multibuffer.end_transaction_at(now, cx);
4560            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
4561            multibuffer.redo(cx);
4562            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
4563            multibuffer.undo(cx);
4564            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
4565            multibuffer.undo(cx);
4566            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
4567
4568            // Transactions can be grouped manually.
4569            multibuffer.redo(cx);
4570            multibuffer.redo(cx);
4571            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
4572            multibuffer.group_until_transaction(transaction_1, cx);
4573            multibuffer.undo(cx);
4574            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
4575            multibuffer.redo(cx);
4576            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
4577        });
4578    }
4579}