multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::{HashMap, HashSet};
   7use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
   8use language::{
   9    Buffer, BufferChunks, BufferSnapshot, Chunk, DiagnosticEntry, Event, File, Language, Outline,
  10    OutlineItem, Selection, ToOffset as _, ToPoint as _, TransactionId,
  11};
  12use std::{
  13    cell::{Ref, RefCell},
  14    cmp, fmt, io,
  15    iter::{self, FromIterator},
  16    ops::{Range, Sub},
  17    str,
  18    sync::Arc,
  19    time::{Duration, Instant},
  20};
  21use sum_tree::{Bias, Cursor, SumTree};
  22use text::{
  23    locator::Locator,
  24    rope::TextDimension,
  25    subscription::{Subscription, Topic},
  26    AnchorRangeExt as _, Edit, Point, PointUtf16, TextSummary,
  27};
  28use theme::SyntaxTheme;
  29use util::post_inc;
  30
  31const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  32
  33pub type ExcerptId = Locator;
  34
  35pub struct MultiBuffer {
  36    snapshot: RefCell<MultiBufferSnapshot>,
  37    buffers: RefCell<HashMap<usize, BufferState>>,
  38    subscriptions: Topic,
  39    singleton: bool,
  40    replica_id: ReplicaId,
  41    history: History,
  42}
  43
  44struct History {
  45    next_transaction_id: usize,
  46    undo_stack: Vec<Transaction>,
  47    redo_stack: Vec<Transaction>,
  48    transaction_depth: usize,
  49    group_interval: Duration,
  50}
  51
  52struct Transaction {
  53    id: usize,
  54    buffer_transactions: HashSet<(usize, text::TransactionId)>,
  55    first_edit_at: Instant,
  56    last_edit_at: Instant,
  57}
  58
  59pub trait ToOffset: 'static + fmt::Debug {
  60    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  61}
  62
  63pub trait ToPoint: 'static + fmt::Debug {
  64    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  65}
  66
  67struct BufferState {
  68    buffer: ModelHandle<Buffer>,
  69    last_version: clock::Global,
  70    last_parse_count: usize,
  71    last_selections_update_count: usize,
  72    last_diagnostics_update_count: usize,
  73    excerpts: Vec<ExcerptId>,
  74    _subscriptions: [gpui::Subscription; 2],
  75}
  76
  77#[derive(Clone, Default)]
  78pub struct MultiBufferSnapshot {
  79    excerpts: SumTree<Excerpt>,
  80    parse_count: usize,
  81    diagnostics_update_count: usize,
  82    is_dirty: bool,
  83    has_conflict: bool,
  84}
  85
  86pub struct ExcerptProperties<'a, T> {
  87    pub buffer: &'a ModelHandle<Buffer>,
  88    pub range: Range<T>,
  89}
  90
  91#[derive(Clone)]
  92struct Excerpt {
  93    id: ExcerptId,
  94    buffer_id: usize,
  95    buffer: BufferSnapshot,
  96    range: Range<text::Anchor>,
  97    max_buffer_row: u32,
  98    text_summary: TextSummary,
  99    has_trailing_newline: bool,
 100}
 101
 102#[derive(Clone, Debug, Default)]
 103struct ExcerptSummary {
 104    excerpt_id: ExcerptId,
 105    max_buffer_row: u32,
 106    text: TextSummary,
 107}
 108
 109pub struct MultiBufferRows<'a> {
 110    buffer_row_range: Range<u32>,
 111    excerpts: Cursor<'a, Excerpt, Point>,
 112}
 113
 114pub struct MultiBufferChunks<'a> {
 115    range: Range<usize>,
 116    excerpts: Cursor<'a, Excerpt, usize>,
 117    excerpt_chunks: Option<ExcerptChunks<'a>>,
 118    theme: Option<&'a SyntaxTheme>,
 119}
 120
 121pub struct MultiBufferBytes<'a> {
 122    range: Range<usize>,
 123    excerpts: Cursor<'a, Excerpt, usize>,
 124    excerpt_bytes: Option<ExcerptBytes<'a>>,
 125    chunk: &'a [u8],
 126}
 127
 128struct ExcerptChunks<'a> {
 129    content_chunks: BufferChunks<'a>,
 130    footer_height: usize,
 131}
 132
 133struct ExcerptBytes<'a> {
 134    content_bytes: language::rope::Bytes<'a>,
 135    footer_height: usize,
 136}
 137
 138impl MultiBuffer {
 139    pub fn new(replica_id: ReplicaId) -> Self {
 140        Self {
 141            snapshot: Default::default(),
 142            buffers: Default::default(),
 143            subscriptions: Default::default(),
 144            singleton: false,
 145            replica_id,
 146            history: History {
 147                next_transaction_id: Default::default(),
 148                undo_stack: Default::default(),
 149                redo_stack: Default::default(),
 150                transaction_depth: 0,
 151                group_interval: Duration::from_millis(300),
 152            },
 153        }
 154    }
 155
 156    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 157        let mut this = Self::new(buffer.read(cx).replica_id());
 158        this.singleton = true;
 159        this.push_excerpt(
 160            ExcerptProperties {
 161                buffer: &buffer,
 162                range: text::Anchor::min()..text::Anchor::max(),
 163            },
 164            cx,
 165        );
 166        this
 167    }
 168
 169    #[cfg(any(test, feature = "test-support"))]
 170    pub fn build_simple(text: &str, cx: &mut gpui::MutableAppContext) -> ModelHandle<Self> {
 171        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
 172        cx.add_model(|cx| Self::singleton(buffer, cx))
 173    }
 174
 175    #[cfg(any(test, feature = "test-support"))]
 176    pub fn build_random(
 177        mut rng: &mut impl rand::Rng,
 178        cx: &mut gpui::MutableAppContext,
 179    ) -> ModelHandle<Self> {
 180        use rand::prelude::*;
 181        use std::env;
 182        use text::RandomCharIter;
 183
 184        let max_excerpts = env::var("MAX_EXCERPTS")
 185            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
 186            .unwrap_or(5);
 187        let excerpts = rng.gen_range(1..=max_excerpts);
 188
 189        cx.add_model(|cx| {
 190            let mut multibuffer = MultiBuffer::new(0);
 191            let mut buffers = Vec::new();
 192            for _ in 0..excerpts {
 193                let buffer_handle = if rng.gen() || buffers.is_empty() {
 194                    let text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
 195                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
 196                    let buffer = buffers.last().unwrap();
 197                    log::info!(
 198                        "Creating new buffer {} with text: {:?}",
 199                        buffer.id(),
 200                        buffer.read(cx).text()
 201                    );
 202                    buffers.last().unwrap()
 203                } else {
 204                    buffers.choose(rng).unwrap()
 205                };
 206
 207                let buffer = buffer_handle.read(cx);
 208                let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
 209                let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
 210                let header_height = rng.gen_range(0..=5);
 211                log::info!(
 212                    "Inserting excerpt from buffer {} with header height {} and range {:?}: {:?}",
 213                    buffer_handle.id(),
 214                    header_height,
 215                    start_ix..end_ix,
 216                    &buffer.text()[start_ix..end_ix]
 217                );
 218
 219                multibuffer.push_excerpt(
 220                    ExcerptProperties {
 221                        buffer: buffer_handle,
 222                        range: start_ix..end_ix,
 223                    },
 224                    cx,
 225                );
 226            }
 227            multibuffer
 228        })
 229    }
 230
 231    pub fn replica_id(&self) -> ReplicaId {
 232        self.replica_id
 233    }
 234
 235    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 236        self.sync(cx);
 237        self.snapshot.borrow().clone()
 238    }
 239
 240    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 241        self.sync(cx);
 242        self.snapshot.borrow()
 243    }
 244
 245    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 246        if self.singleton {
 247            return Some(
 248                self.buffers
 249                    .borrow()
 250                    .values()
 251                    .next()
 252                    .unwrap()
 253                    .buffer
 254                    .clone(),
 255            );
 256        } else {
 257            None
 258        }
 259    }
 260
 261    pub fn subscribe(&mut self) -> Subscription {
 262        self.subscriptions.subscribe()
 263    }
 264
 265    pub fn edit<I, S, T>(&mut self, ranges: I, new_text: T, cx: &mut ModelContext<Self>)
 266    where
 267        I: IntoIterator<Item = Range<S>>,
 268        S: ToOffset,
 269        T: Into<String>,
 270    {
 271        self.edit_internal(ranges, new_text, false, cx)
 272    }
 273
 274    pub fn edit_with_autoindent<I, S, T>(
 275        &mut self,
 276        ranges: I,
 277        new_text: T,
 278        cx: &mut ModelContext<Self>,
 279    ) where
 280        I: IntoIterator<Item = Range<S>>,
 281        S: ToOffset,
 282        T: Into<String>,
 283    {
 284        self.edit_internal(ranges, new_text, true, cx)
 285    }
 286
 287    pub fn edit_internal<I, S, T>(
 288        &mut self,
 289        ranges_iter: I,
 290        new_text: T,
 291        autoindent: bool,
 292        cx: &mut ModelContext<Self>,
 293    ) where
 294        I: IntoIterator<Item = Range<S>>,
 295        S: ToOffset,
 296        T: Into<String>,
 297    {
 298        if let Some(buffer) = self.as_singleton() {
 299            let snapshot = self.read(cx);
 300            let ranges = ranges_iter
 301                .into_iter()
 302                .map(|range| range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot));
 303            return buffer.update(cx, |buffer, cx| {
 304                if autoindent {
 305                    buffer.edit_with_autoindent(ranges, new_text, cx)
 306                } else {
 307                    buffer.edit(ranges, new_text, cx)
 308                }
 309            });
 310        }
 311
 312        let snapshot = self.read(cx);
 313        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, bool)>> = Default::default();
 314        let mut cursor = snapshot.excerpts.cursor::<usize>();
 315        for range in ranges_iter {
 316            let start = range.start.to_offset(&snapshot);
 317            let end = range.end.to_offset(&snapshot);
 318            cursor.seek(&start, Bias::Right, &());
 319            if cursor.item().is_none() && start == *cursor.start() {
 320                cursor.prev(&());
 321            }
 322            let start_excerpt = cursor.item().expect("start offset out of bounds");
 323            let start_overshoot = start - cursor.start();
 324            let buffer_start =
 325                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 326
 327            cursor.seek(&end, Bias::Right, &());
 328            if cursor.item().is_none() && end == *cursor.start() {
 329                cursor.prev(&());
 330            }
 331            let end_excerpt = cursor.item().expect("end offset out of bounds");
 332            let end_overshoot = end - cursor.start();
 333            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 334
 335            if start_excerpt.id == end_excerpt.id {
 336                buffer_edits
 337                    .entry(start_excerpt.buffer_id)
 338                    .or_insert(Vec::new())
 339                    .push((buffer_start..buffer_end, true));
 340            } else {
 341                let start_excerpt_range =
 342                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 343                let end_excerpt_range =
 344                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 345                buffer_edits
 346                    .entry(start_excerpt.buffer_id)
 347                    .or_insert(Vec::new())
 348                    .push((start_excerpt_range, true));
 349                buffer_edits
 350                    .entry(end_excerpt.buffer_id)
 351                    .or_insert(Vec::new())
 352                    .push((end_excerpt_range, false));
 353
 354                cursor.seek(&start, Bias::Right, &());
 355                cursor.next(&());
 356                while let Some(excerpt) = cursor.item() {
 357                    if excerpt.id == end_excerpt.id {
 358                        break;
 359                    }
 360                    buffer_edits
 361                        .entry(excerpt.buffer_id)
 362                        .or_insert(Vec::new())
 363                        .push((excerpt.range.to_offset(&excerpt.buffer), false));
 364                    cursor.next(&());
 365                }
 366            }
 367        }
 368
 369        let new_text = new_text.into();
 370        for (buffer_id, mut edits) in buffer_edits {
 371            edits.sort_unstable_by_key(|(range, _)| range.start);
 372            self.buffers.borrow()[&buffer_id]
 373                .buffer
 374                .update(cx, |buffer, cx| {
 375                    let mut edits = edits.into_iter().peekable();
 376                    let mut insertions = Vec::new();
 377                    let mut deletions = Vec::new();
 378                    while let Some((mut range, mut is_insertion)) = edits.next() {
 379                        while let Some((next_range, next_is_insertion)) = edits.peek() {
 380                            if range.end >= next_range.start {
 381                                range.end = cmp::max(next_range.end, range.end);
 382                                is_insertion |= *next_is_insertion;
 383                                edits.next();
 384                            } else {
 385                                break;
 386                            }
 387                        }
 388
 389                        if is_insertion {
 390                            insertions.push(
 391                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 392                            );
 393                        } else if !range.is_empty() {
 394                            deletions.push(
 395                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 396                            );
 397                        }
 398                    }
 399
 400                    if autoindent {
 401                        buffer.edit_with_autoindent(deletions, "", cx);
 402                        buffer.edit_with_autoindent(insertions, new_text.clone(), cx);
 403                    } else {
 404                        buffer.edit(deletions, "", cx);
 405                        buffer.edit(insertions, new_text.clone(), cx);
 406                    }
 407                })
 408        }
 409    }
 410
 411    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 412        self.start_transaction_at(Instant::now(), cx)
 413    }
 414
 415    pub(crate) fn start_transaction_at(
 416        &mut self,
 417        now: Instant,
 418        cx: &mut ModelContext<Self>,
 419    ) -> Option<TransactionId> {
 420        if let Some(buffer) = self.as_singleton() {
 421            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 422        }
 423
 424        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 425            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 426        }
 427        self.history.start_transaction(now)
 428    }
 429
 430    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 431        self.end_transaction_at(Instant::now(), cx)
 432    }
 433
 434    pub(crate) fn end_transaction_at(
 435        &mut self,
 436        now: Instant,
 437        cx: &mut ModelContext<Self>,
 438    ) -> Option<TransactionId> {
 439        if let Some(buffer) = self.as_singleton() {
 440            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 441        }
 442
 443        let mut buffer_transactions = HashSet::default();
 444        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 445            if let Some(transaction_id) =
 446                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 447            {
 448                buffer_transactions.insert((buffer.id(), transaction_id));
 449            }
 450        }
 451
 452        if self.history.end_transaction(now, buffer_transactions) {
 453            let transaction_id = self.history.group().unwrap();
 454            Some(transaction_id)
 455        } else {
 456            None
 457        }
 458    }
 459
 460    pub fn set_active_selections(
 461        &mut self,
 462        selections: &[Selection<Anchor>],
 463        cx: &mut ModelContext<Self>,
 464    ) {
 465        let mut selections_by_buffer: HashMap<usize, Vec<Selection<text::Anchor>>> =
 466            Default::default();
 467        let snapshot = self.read(cx);
 468        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 469        for selection in selections {
 470            cursor.seek(&Some(&selection.start.excerpt_id), Bias::Left, &());
 471            while let Some(excerpt) = cursor.item() {
 472                if excerpt.id > selection.end.excerpt_id {
 473                    break;
 474                }
 475
 476                let mut start = excerpt.range.start.clone();
 477                let mut end = excerpt.range.end.clone();
 478                if excerpt.id == selection.start.excerpt_id {
 479                    start = selection.start.text_anchor.clone();
 480                }
 481                if excerpt.id == selection.end.excerpt_id {
 482                    end = selection.end.text_anchor.clone();
 483                }
 484                selections_by_buffer
 485                    .entry(excerpt.buffer_id)
 486                    .or_default()
 487                    .push(Selection {
 488                        id: selection.id,
 489                        start,
 490                        end,
 491                        reversed: selection.reversed,
 492                        goal: selection.goal,
 493                    });
 494
 495                cursor.next(&());
 496            }
 497        }
 498
 499        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 500            if !selections_by_buffer.contains_key(buffer_id) {
 501                buffer_state
 502                    .buffer
 503                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 504            }
 505        }
 506
 507        for (buffer_id, mut selections) in selections_by_buffer {
 508            self.buffers.borrow()[&buffer_id]
 509                .buffer
 510                .update(cx, |buffer, cx| {
 511                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer).unwrap());
 512                    let mut selections = selections.into_iter().peekable();
 513                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 514                        let mut selection = selections.next()?;
 515                        while let Some(next_selection) = selections.peek() {
 516                            if selection
 517                                .end
 518                                .cmp(&next_selection.start, buffer)
 519                                .unwrap()
 520                                .is_ge()
 521                            {
 522                                let next_selection = selections.next().unwrap();
 523                                if next_selection
 524                                    .end
 525                                    .cmp(&selection.end, buffer)
 526                                    .unwrap()
 527                                    .is_ge()
 528                                {
 529                                    selection.end = next_selection.end;
 530                                }
 531                            } else {
 532                                break;
 533                            }
 534                        }
 535                        Some(selection)
 536                    }));
 537                    buffer.set_active_selections(merged_selections, cx);
 538                });
 539        }
 540    }
 541
 542    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 543        for buffer in self.buffers.borrow().values() {
 544            buffer
 545                .buffer
 546                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 547        }
 548    }
 549
 550    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 551        if let Some(buffer) = self.as_singleton() {
 552            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 553        }
 554
 555        while let Some(transaction) = self.history.pop_undo() {
 556            let mut undone = false;
 557            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 558                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 559                    undone |= buffer.update(cx, |buf, cx| {
 560                        buf.undo_transaction(*buffer_transaction_id, cx)
 561                    });
 562                }
 563            }
 564
 565            if undone {
 566                return Some(transaction.id);
 567            }
 568        }
 569
 570        None
 571    }
 572
 573    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 574        if let Some(buffer) = self.as_singleton() {
 575            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 576        }
 577
 578        while let Some(transaction) = self.history.pop_redo() {
 579            let mut redone = false;
 580            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 581                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 582                    redone |= buffer.update(cx, |buf, cx| {
 583                        buf.redo_transaction(*buffer_transaction_id, cx)
 584                    });
 585                }
 586            }
 587
 588            if redone {
 589                return Some(transaction.id);
 590            }
 591        }
 592
 593        None
 594    }
 595
 596    pub fn push_excerpt<O>(
 597        &mut self,
 598        props: ExcerptProperties<O>,
 599        cx: &mut ModelContext<Self>,
 600    ) -> ExcerptId
 601    where
 602        O: text::ToOffset,
 603    {
 604        self.insert_excerpt_after(&ExcerptId::max(), props, cx)
 605    }
 606
 607    pub fn insert_excerpt_after<O>(
 608        &mut self,
 609        prev_excerpt_id: &ExcerptId,
 610        props: ExcerptProperties<O>,
 611        cx: &mut ModelContext<Self>,
 612    ) -> ExcerptId
 613    where
 614        O: text::ToOffset,
 615    {
 616        assert_eq!(self.history.transaction_depth, 0);
 617        self.sync(cx);
 618
 619        let buffer_snapshot = props.buffer.read(cx).snapshot();
 620        let range = buffer_snapshot.anchor_before(&props.range.start)
 621            ..buffer_snapshot.anchor_after(&props.range.end);
 622        let mut snapshot = self.snapshot.borrow_mut();
 623        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 624        let mut new_excerpts = cursor.slice(&Some(prev_excerpt_id), Bias::Right, &());
 625
 626        let mut prev_id = ExcerptId::min();
 627        let edit_start = new_excerpts.summary().text.bytes;
 628        new_excerpts.update_last(
 629            |excerpt| {
 630                excerpt.has_trailing_newline = true;
 631                prev_id = excerpt.id.clone();
 632            },
 633            &(),
 634        );
 635
 636        let mut next_id = ExcerptId::max();
 637        if let Some(next_excerpt) = cursor.item() {
 638            next_id = next_excerpt.id.clone();
 639        }
 640
 641        let id = ExcerptId::between(&prev_id, &next_id);
 642
 643        let mut buffers = self.buffers.borrow_mut();
 644        let buffer_state = buffers
 645            .entry(props.buffer.id())
 646            .or_insert_with(|| BufferState {
 647                last_version: buffer_snapshot.version().clone(),
 648                last_parse_count: buffer_snapshot.parse_count(),
 649                last_selections_update_count: buffer_snapshot.selections_update_count(),
 650                last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 651                excerpts: Default::default(),
 652                _subscriptions: [
 653                    cx.observe(&props.buffer, |_, _, cx| cx.notify()),
 654                    cx.subscribe(&props.buffer, Self::on_buffer_event),
 655                ],
 656                buffer: props.buffer.clone(),
 657            });
 658        if let Err(ix) = buffer_state.excerpts.binary_search(&id) {
 659            buffer_state.excerpts.insert(ix, id.clone());
 660        }
 661
 662        let excerpt = Excerpt::new(
 663            id.clone(),
 664            props.buffer.id(),
 665            buffer_snapshot,
 666            range,
 667            cursor.item().is_some(),
 668        );
 669        new_excerpts.push(excerpt, &());
 670        let edit_end = new_excerpts.summary().text.bytes;
 671
 672        new_excerpts.push_tree(cursor.suffix(&()), &());
 673        drop(cursor);
 674        snapshot.excerpts = new_excerpts;
 675
 676        self.subscriptions.publish_mut([Edit {
 677            old: edit_start..edit_start,
 678            new: edit_start..edit_end,
 679        }]);
 680
 681        cx.notify();
 682        id
 683    }
 684
 685    pub fn excerpt_ids_for_buffer(&self, buffer: &ModelHandle<Buffer>) -> Vec<ExcerptId> {
 686        self.buffers
 687            .borrow()
 688            .get(&buffer.id())
 689            .map_or(Vec::new(), |state| state.excerpts.clone())
 690    }
 691
 692    pub fn excerpted_buffers<'a, T: ToOffset>(
 693        &'a self,
 694        range: Range<T>,
 695        cx: &AppContext,
 696    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 697        let snapshot = self.snapshot(cx);
 698        let start = range.start.to_offset(&snapshot);
 699        let end = range.end.to_offset(&snapshot);
 700
 701        let mut result = Vec::new();
 702        let mut cursor = snapshot.excerpts.cursor::<usize>();
 703        cursor.seek(&start, Bias::Right, &());
 704        while let Some(excerpt) = cursor.item() {
 705            if *cursor.start() > end {
 706                break;
 707            }
 708
 709            let mut end_before_newline = cursor.end(&());
 710            if excerpt.has_trailing_newline {
 711                end_before_newline -= 1;
 712            }
 713            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 714            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 715            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 716            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 717            result.push((buffer, start..end));
 718            cursor.next(&());
 719        }
 720
 721        result
 722    }
 723
 724    pub fn remove_excerpts<'a>(
 725        &mut self,
 726        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 727        cx: &mut ModelContext<Self>,
 728    ) {
 729        let mut buffers = self.buffers.borrow_mut();
 730        let mut snapshot = self.snapshot.borrow_mut();
 731        let mut new_excerpts = SumTree::new();
 732        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 733        let mut edits = Vec::new();
 734        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 735
 736        while let Some(mut excerpt_id) = excerpt_ids.next() {
 737            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 738            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 739            if let Some(mut excerpt) = cursor.item() {
 740                if excerpt.id != *excerpt_id {
 741                    continue;
 742                }
 743                let mut old_start = cursor.start().1;
 744
 745                // Skip over the removed excerpt.
 746                loop {
 747                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 748                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 749                        if buffer_state.excerpts.is_empty() {
 750                            buffers.remove(&excerpt.buffer_id);
 751                        }
 752                    }
 753                    cursor.next(&());
 754
 755                    // Skip over any subsequent excerpts that are also removed.
 756                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 757                        if let Some(next_excerpt) = cursor.item() {
 758                            if next_excerpt.id == *next_excerpt_id {
 759                                excerpt = next_excerpt;
 760                                excerpt_id = excerpt_ids.next().unwrap();
 761                                continue;
 762                            }
 763                        }
 764                    }
 765
 766                    break;
 767                }
 768
 769                // When removing the last excerpt, remove the trailing newline from
 770                // the previous excerpt.
 771                if cursor.item().is_none() && old_start > 0 {
 772                    old_start -= 1;
 773                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 774                }
 775
 776                // Push an edit for the removal of this run of excerpts.
 777                let old_end = cursor.start().1;
 778                let new_start = new_excerpts.summary().text.bytes;
 779                edits.push(Edit {
 780                    old: old_start..old_end,
 781                    new: new_start..new_start,
 782                });
 783            }
 784        }
 785        new_excerpts.push_tree(cursor.suffix(&()), &());
 786        drop(cursor);
 787        snapshot.excerpts = new_excerpts;
 788        self.subscriptions.publish_mut(edits);
 789        cx.notify();
 790    }
 791
 792    fn on_buffer_event(
 793        &mut self,
 794        _: ModelHandle<Buffer>,
 795        event: &Event,
 796        cx: &mut ModelContext<Self>,
 797    ) {
 798        cx.emit(event.clone());
 799    }
 800
 801    pub fn format(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 802        let mut format_tasks = Vec::new();
 803        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 804            format_tasks.push(buffer.update(cx, |buffer, cx| buffer.format(cx)));
 805        }
 806
 807        cx.spawn(|_, _| async move {
 808            for format in format_tasks {
 809                format.await?;
 810            }
 811            Ok(())
 812        })
 813    }
 814
 815    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Result<Task<Result<()>>> {
 816        let mut save_tasks = Vec::new();
 817        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 818            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx))?);
 819        }
 820
 821        Ok(cx.spawn(|_, _| async move {
 822            for save in save_tasks {
 823                save.await?;
 824            }
 825            Ok(())
 826        }))
 827    }
 828
 829    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 830        self.buffers
 831            .borrow()
 832            .values()
 833            .next()
 834            .and_then(|state| state.buffer.read(cx).language())
 835    }
 836
 837    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 838        self.as_singleton()?.read(cx).file()
 839    }
 840
 841    #[cfg(test)]
 842    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 843        self.as_singleton().unwrap().read(cx).is_parsing()
 844    }
 845
 846    fn sync(&self, cx: &AppContext) {
 847        let mut snapshot = self.snapshot.borrow_mut();
 848        let mut excerpts_to_edit = Vec::new();
 849        let mut reparsed = false;
 850        let mut diagnostics_updated = false;
 851        let mut is_dirty = false;
 852        let mut has_conflict = false;
 853        let mut buffers = self.buffers.borrow_mut();
 854        for buffer_state in buffers.values_mut() {
 855            let buffer = buffer_state.buffer.read(cx);
 856            let version = buffer.version();
 857            let parse_count = buffer.parse_count();
 858            let selections_update_count = buffer.selections_update_count();
 859            let diagnostics_update_count = buffer.diagnostics_update_count();
 860
 861            let buffer_edited = version.changed_since(&buffer_state.last_version);
 862            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
 863            let buffer_selections_updated =
 864                selections_update_count > buffer_state.last_selections_update_count;
 865            let buffer_diagnostics_updated =
 866                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
 867            if buffer_edited
 868                || buffer_reparsed
 869                || buffer_selections_updated
 870                || buffer_diagnostics_updated
 871            {
 872                buffer_state.last_version = version;
 873                buffer_state.last_parse_count = parse_count;
 874                buffer_state.last_selections_update_count = selections_update_count;
 875                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
 876                excerpts_to_edit.extend(
 877                    buffer_state
 878                        .excerpts
 879                        .iter()
 880                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
 881                );
 882            }
 883
 884            reparsed |= buffer_reparsed;
 885            diagnostics_updated |= buffer_diagnostics_updated;
 886            is_dirty |= buffer.is_dirty();
 887            has_conflict |= buffer.has_conflict();
 888        }
 889        if reparsed {
 890            snapshot.parse_count += 1;
 891        }
 892        if diagnostics_updated {
 893            snapshot.diagnostics_update_count += 1;
 894        }
 895        snapshot.is_dirty = is_dirty;
 896        snapshot.has_conflict = has_conflict;
 897
 898        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
 899
 900        let mut edits = Vec::new();
 901        let mut new_excerpts = SumTree::new();
 902        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 903
 904        for (id, buffer, buffer_edited) in excerpts_to_edit {
 905            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
 906            let old_excerpt = cursor.item().unwrap();
 907            let buffer_id = buffer.id();
 908            let buffer = buffer.read(cx);
 909
 910            let mut new_excerpt;
 911            if buffer_edited {
 912                edits.extend(
 913                    buffer
 914                        .edits_since_in_range::<usize>(
 915                            old_excerpt.buffer.version(),
 916                            old_excerpt.range.clone(),
 917                        )
 918                        .map(|mut edit| {
 919                            let excerpt_old_start = cursor.start().1;
 920                            let excerpt_new_start = new_excerpts.summary().text.bytes;
 921                            edit.old.start += excerpt_old_start;
 922                            edit.old.end += excerpt_old_start;
 923                            edit.new.start += excerpt_new_start;
 924                            edit.new.end += excerpt_new_start;
 925                            edit
 926                        }),
 927                );
 928
 929                new_excerpt = Excerpt::new(
 930                    id.clone(),
 931                    buffer_id,
 932                    buffer.snapshot(),
 933                    old_excerpt.range.clone(),
 934                    old_excerpt.has_trailing_newline,
 935                );
 936            } else {
 937                new_excerpt = old_excerpt.clone();
 938                new_excerpt.buffer = buffer.snapshot();
 939            }
 940
 941            new_excerpts.push(new_excerpt, &());
 942            cursor.next(&());
 943        }
 944        new_excerpts.push_tree(cursor.suffix(&()), &());
 945
 946        drop(cursor);
 947        snapshot.excerpts = new_excerpts;
 948
 949        self.subscriptions.publish(edits);
 950    }
 951}
 952
 953#[cfg(any(test, feature = "test-support"))]
 954impl MultiBuffer {
 955    pub fn randomly_edit(
 956        &mut self,
 957        rng: &mut impl rand::Rng,
 958        count: usize,
 959        cx: &mut ModelContext<Self>,
 960    ) {
 961        use text::RandomCharIter;
 962
 963        let snapshot = self.read(cx);
 964        let mut old_ranges: Vec<Range<usize>> = Vec::new();
 965        for _ in 0..count {
 966            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
 967            if last_end > snapshot.len() {
 968                break;
 969            }
 970            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
 971            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
 972            old_ranges.push(start_ix..end_ix);
 973        }
 974        let new_text_len = rng.gen_range(0..10);
 975        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
 976        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
 977        drop(snapshot);
 978
 979        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
 980    }
 981}
 982
 983impl Entity for MultiBuffer {
 984    type Event = language::Event;
 985}
 986
 987impl MultiBufferSnapshot {
 988    pub fn text(&self) -> String {
 989        self.chunks(0..self.len(), None)
 990            .map(|chunk| chunk.text)
 991            .collect()
 992    }
 993
 994    pub fn reversed_chars_at<'a, T: ToOffset>(
 995        &'a self,
 996        position: T,
 997    ) -> impl Iterator<Item = char> + 'a {
 998        let mut offset = position.to_offset(self);
 999        let mut cursor = self.excerpts.cursor::<usize>();
1000        cursor.seek(&offset, Bias::Left, &());
1001        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1002            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1003            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1004            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1005            excerpt.buffer.reversed_chunks_in_range(start..end)
1006        });
1007        iter::from_fn(move || {
1008            if offset == *cursor.start() {
1009                cursor.prev(&());
1010                let excerpt = cursor.item()?;
1011                excerpt_chunks = Some(
1012                    excerpt
1013                        .buffer
1014                        .reversed_chunks_in_range(excerpt.range.clone()),
1015                );
1016            }
1017
1018            let excerpt = cursor.item().unwrap();
1019            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1020                offset -= 1;
1021                Some("\n")
1022            } else {
1023                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1024                offset -= chunk.len();
1025                Some(chunk)
1026            }
1027        })
1028        .flat_map(|c| c.chars().rev())
1029    }
1030
1031    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1032        let offset = position.to_offset(self);
1033        self.text_for_range(offset..self.len())
1034            .flat_map(|chunk| chunk.chars())
1035    }
1036
1037    pub fn text_for_range<'a, T: ToOffset>(
1038        &'a self,
1039        range: Range<T>,
1040    ) -> impl Iterator<Item = &'a str> {
1041        self.chunks(range, None).map(|chunk| chunk.text)
1042    }
1043
1044    pub fn is_line_blank(&self, row: u32) -> bool {
1045        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1046            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1047    }
1048
1049    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1050    where
1051        T: ToOffset,
1052    {
1053        let position = position.to_offset(self);
1054        position == self.clip_offset(position, Bias::Left)
1055            && self
1056                .bytes_in_range(position..self.len())
1057                .flatten()
1058                .copied()
1059                .take(needle.len())
1060                .eq(needle.bytes())
1061    }
1062
1063    fn as_singleton(&self) -> Option<&BufferSnapshot> {
1064        let mut excerpts = self.excerpts.iter();
1065        let buffer = excerpts.next().map(|excerpt| &excerpt.buffer);
1066        if excerpts.next().is_none() {
1067            buffer
1068        } else {
1069            None
1070        }
1071    }
1072
1073    pub fn len(&self) -> usize {
1074        self.excerpts.summary().text.bytes
1075    }
1076
1077    pub fn max_buffer_row(&self) -> u32 {
1078        self.excerpts.summary().max_buffer_row
1079    }
1080
1081    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1082        let mut cursor = self.excerpts.cursor::<usize>();
1083        cursor.seek(&offset, Bias::Right, &());
1084        let overshoot = if let Some(excerpt) = cursor.item() {
1085            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1086            let buffer_offset = excerpt
1087                .buffer
1088                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1089            buffer_offset.saturating_sub(excerpt_start)
1090        } else {
1091            0
1092        };
1093        cursor.start() + overshoot
1094    }
1095
1096    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1097        let mut cursor = self.excerpts.cursor::<Point>();
1098        cursor.seek(&point, Bias::Right, &());
1099        let overshoot = if let Some(excerpt) = cursor.item() {
1100            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1101            let buffer_point = excerpt
1102                .buffer
1103                .clip_point(excerpt_start + (point - cursor.start()), bias);
1104            buffer_point.saturating_sub(excerpt_start)
1105        } else {
1106            Point::zero()
1107        };
1108        *cursor.start() + overshoot
1109    }
1110
1111    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1112        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1113        cursor.seek(&point, Bias::Right, &());
1114        let overshoot = if let Some(excerpt) = cursor.item() {
1115            let excerpt_start = excerpt
1116                .buffer
1117                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1118            let buffer_point = excerpt
1119                .buffer
1120                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1121            buffer_point.saturating_sub(excerpt_start)
1122        } else {
1123            PointUtf16::zero()
1124        };
1125        *cursor.start() + overshoot
1126    }
1127
1128    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1129        let range = range.start.to_offset(self)..range.end.to_offset(self);
1130        let mut excerpts = self.excerpts.cursor::<usize>();
1131        excerpts.seek(&range.start, Bias::Right, &());
1132
1133        let mut chunk = &[][..];
1134        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1135            let mut excerpt_bytes = excerpt
1136                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1137            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1138            Some(excerpt_bytes)
1139        } else {
1140            None
1141        };
1142
1143        MultiBufferBytes {
1144            range,
1145            excerpts,
1146            excerpt_bytes,
1147            chunk,
1148        }
1149    }
1150
1151    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1152        let mut result = MultiBufferRows {
1153            buffer_row_range: 0..0,
1154            excerpts: self.excerpts.cursor(),
1155        };
1156        result.seek(start_row);
1157        result
1158    }
1159
1160    pub fn chunks<'a, T: ToOffset>(
1161        &'a self,
1162        range: Range<T>,
1163        theme: Option<&'a SyntaxTheme>,
1164    ) -> MultiBufferChunks<'a> {
1165        let range = range.start.to_offset(self)..range.end.to_offset(self);
1166        let mut chunks = MultiBufferChunks {
1167            range: range.clone(),
1168            excerpts: self.excerpts.cursor(),
1169            excerpt_chunks: None,
1170            theme,
1171        };
1172        chunks.seek(range.start);
1173        chunks
1174    }
1175
1176    pub fn offset_to_point(&self, offset: usize) -> Point {
1177        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1178        cursor.seek(&offset, Bias::Right, &());
1179        if let Some(excerpt) = cursor.item() {
1180            let (start_offset, start_point) = cursor.start();
1181            let overshoot = offset - start_offset;
1182            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1183            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1184            let buffer_point = excerpt
1185                .buffer
1186                .offset_to_point(excerpt_start_offset + overshoot);
1187            *start_point + (buffer_point - excerpt_start_point)
1188        } else {
1189            self.excerpts.summary().text.lines
1190        }
1191    }
1192
1193    pub fn point_to_offset(&self, point: Point) -> usize {
1194        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1195        cursor.seek(&point, Bias::Right, &());
1196        if let Some(excerpt) = cursor.item() {
1197            let (start_point, start_offset) = cursor.start();
1198            let overshoot = point - start_point;
1199            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1200            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1201            let buffer_offset = excerpt
1202                .buffer
1203                .point_to_offset(excerpt_start_point + overshoot);
1204            *start_offset + buffer_offset - excerpt_start_offset
1205        } else {
1206            self.excerpts.summary().text.bytes
1207        }
1208    }
1209
1210    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1211        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1212        cursor.seek(&point, Bias::Right, &());
1213        if let Some(excerpt) = cursor.item() {
1214            let (start_point, start_offset) = cursor.start();
1215            let overshoot = point - start_point;
1216            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1217            let excerpt_start_point = excerpt
1218                .buffer
1219                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1220            let buffer_offset = excerpt
1221                .buffer
1222                .point_utf16_to_offset(excerpt_start_point + overshoot);
1223            *start_offset + (buffer_offset - excerpt_start_offset)
1224        } else {
1225            self.excerpts.summary().text.bytes
1226        }
1227    }
1228
1229    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1230        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1231            buffer
1232                .indent_column_for_line(range.start.row)
1233                .min(range.end.column)
1234                .saturating_sub(range.start.column)
1235        } else {
1236            0
1237        }
1238    }
1239
1240    pub fn line_len(&self, row: u32) -> u32 {
1241        if let Some((_, range)) = self.buffer_line_for_row(row) {
1242            range.end.column - range.start.column
1243        } else {
1244            0
1245        }
1246    }
1247
1248    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1249        let mut cursor = self.excerpts.cursor::<Point>();
1250        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1251        if let Some(excerpt) = cursor.item() {
1252            let overshoot = row - cursor.start().row;
1253            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1254            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1255            let buffer_row = excerpt_start.row + overshoot;
1256            let line_start = Point::new(buffer_row, 0);
1257            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1258            return Some((
1259                &excerpt.buffer,
1260                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1261            ));
1262        }
1263        None
1264    }
1265
1266    pub fn max_point(&self) -> Point {
1267        self.text_summary().lines
1268    }
1269
1270    pub fn text_summary(&self) -> TextSummary {
1271        self.excerpts.summary().text
1272    }
1273
1274    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1275    where
1276        D: TextDimension,
1277        O: ToOffset,
1278    {
1279        let mut summary = D::default();
1280        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1281        let mut cursor = self.excerpts.cursor::<usize>();
1282        cursor.seek(&range.start, Bias::Right, &());
1283        if let Some(excerpt) = cursor.item() {
1284            let mut end_before_newline = cursor.end(&());
1285            if excerpt.has_trailing_newline {
1286                end_before_newline -= 1;
1287            }
1288
1289            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1290            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1291            let end_in_excerpt =
1292                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1293            summary.add_assign(
1294                &excerpt
1295                    .buffer
1296                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1297            );
1298
1299            if range.end > end_before_newline {
1300                summary.add_assign(&D::from_text_summary(&TextSummary {
1301                    bytes: 1,
1302                    lines: Point::new(1 as u32, 0),
1303                    lines_utf16: PointUtf16::new(1 as u32, 0),
1304                    first_line_chars: 0,
1305                    last_line_chars: 0,
1306                    longest_row: 0,
1307                    longest_row_chars: 0,
1308                }));
1309            }
1310
1311            cursor.next(&());
1312        }
1313
1314        if range.end > *cursor.start() {
1315            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1316                &range.end,
1317                Bias::Right,
1318                &(),
1319            )));
1320            if let Some(excerpt) = cursor.item() {
1321                range.end = cmp::max(*cursor.start(), range.end);
1322
1323                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1324                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1325                summary.add_assign(
1326                    &excerpt
1327                        .buffer
1328                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1329                );
1330            }
1331        }
1332
1333        summary
1334    }
1335
1336    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1337    where
1338        D: TextDimension + Ord + Sub<D, Output = D>,
1339    {
1340        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1341        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1342        if cursor.item().is_none() {
1343            cursor.next(&());
1344        }
1345
1346        let mut position = D::from_text_summary(&cursor.start().text);
1347        if let Some(excerpt) = cursor.item() {
1348            if excerpt.id == anchor.excerpt_id && excerpt.buffer_id == anchor.buffer_id {
1349                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1350                let buffer_position = anchor.text_anchor.summary::<D>(&excerpt.buffer);
1351                if buffer_position > excerpt_buffer_start {
1352                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1353                }
1354            }
1355        }
1356        position
1357    }
1358
1359    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1360    where
1361        D: TextDimension + Ord + Sub<D, Output = D>,
1362        I: 'a + IntoIterator<Item = &'a Anchor>,
1363    {
1364        let mut anchors = anchors.into_iter().peekable();
1365        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1366        let mut summaries = Vec::new();
1367        while let Some(anchor) = anchors.peek() {
1368            let excerpt_id = &anchor.excerpt_id;
1369            let buffer_id = anchor.buffer_id;
1370            let excerpt_anchors = iter::from_fn(|| {
1371                let anchor = anchors.peek()?;
1372                if anchor.excerpt_id == *excerpt_id && anchor.buffer_id == buffer_id {
1373                    Some(&anchors.next().unwrap().text_anchor)
1374                } else {
1375                    None
1376                }
1377            });
1378
1379            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1380            if cursor.item().is_none() {
1381                cursor.next(&());
1382            }
1383
1384            let position = D::from_text_summary(&cursor.start().text);
1385            if let Some(excerpt) = cursor.item() {
1386                if excerpt.id == *excerpt_id && excerpt.buffer_id == buffer_id {
1387                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1388                    summaries.extend(
1389                        excerpt
1390                            .buffer
1391                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1392                            .map(move |summary| {
1393                                let mut position = position.clone();
1394                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1395                                if summary > excerpt_buffer_start {
1396                                    position.add_assign(&(summary - excerpt_buffer_start));
1397                                }
1398                                position
1399                            }),
1400                    );
1401                    continue;
1402                }
1403            }
1404
1405            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1406        }
1407
1408        summaries
1409    }
1410
1411    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1412    where
1413        I: 'a + IntoIterator<Item = &'a Anchor>,
1414    {
1415        let mut anchors = anchors.into_iter().enumerate().peekable();
1416        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1417        let mut result = Vec::new();
1418        while let Some((_, anchor)) = anchors.peek() {
1419            let old_excerpt_id = &anchor.excerpt_id;
1420
1421            // Find the location where this anchor's excerpt should be.
1422            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1423            if cursor.item().is_none() {
1424                cursor.next(&());
1425            }
1426
1427            let next_excerpt = cursor.item();
1428            let prev_excerpt = cursor.prev_item();
1429
1430            // Process all of the anchors for this excerpt.
1431            while let Some((_, anchor)) = anchors.peek() {
1432                if anchor.excerpt_id != *old_excerpt_id {
1433                    break;
1434                }
1435                let mut kept_position = false;
1436                let (anchor_ix, anchor) = anchors.next().unwrap();
1437                let mut anchor = anchor.clone();
1438
1439                // Leave min and max anchors unchanged.
1440                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1441                    kept_position = true;
1442                }
1443                // If the old excerpt still exists at this location, then leave
1444                // the anchor unchanged.
1445                else if next_excerpt.map_or(false, |excerpt| {
1446                    excerpt.id == *old_excerpt_id && excerpt.buffer_id == anchor.buffer_id
1447                }) {
1448                    kept_position = true;
1449                }
1450                // If the old excerpt no longer exists at this location, then attempt to
1451                // find an equivalent position for this anchor in an adjacent excerpt.
1452                else {
1453                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1454                        if excerpt.contains(&anchor) {
1455                            anchor.excerpt_id = excerpt.id.clone();
1456                            kept_position = true;
1457                            break;
1458                        }
1459                    }
1460                }
1461                // If there's no adjacent excerpt that contains the anchor's position,
1462                // then report that the anchor has lost its position.
1463                if !kept_position {
1464                    anchor = if let Some(excerpt) = next_excerpt {
1465                        Anchor {
1466                            buffer_id: excerpt.buffer_id,
1467                            excerpt_id: excerpt.id.clone(),
1468                            text_anchor: excerpt
1469                                .buffer
1470                                .anchor_at(&excerpt.range.start, anchor.text_anchor.bias),
1471                        }
1472                    } else if let Some(excerpt) = prev_excerpt {
1473                        Anchor {
1474                            buffer_id: excerpt.buffer_id,
1475                            excerpt_id: excerpt.id.clone(),
1476                            text_anchor: excerpt
1477                                .buffer
1478                                .anchor_at(&excerpt.range.end, anchor.text_anchor.bias),
1479                        }
1480                    } else if anchor.text_anchor.bias == Bias::Left {
1481                        Anchor::min()
1482                    } else {
1483                        Anchor::max()
1484                    };
1485                }
1486
1487                result.push((anchor_ix, anchor, kept_position));
1488            }
1489        }
1490        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self).unwrap());
1491        result
1492    }
1493
1494    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1495        self.anchor_at(position, Bias::Left)
1496    }
1497
1498    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1499        self.anchor_at(position, Bias::Right)
1500    }
1501
1502    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1503        let offset = position.to_offset(self);
1504        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1505        cursor.seek(&offset, Bias::Right, &());
1506        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1507            cursor.prev(&());
1508        }
1509        if let Some(excerpt) = cursor.item() {
1510            let mut overshoot = offset.saturating_sub(cursor.start().0);
1511            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1512                overshoot -= 1;
1513                bias = Bias::Right;
1514            }
1515
1516            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1517            let text_anchor =
1518                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1519            Anchor {
1520                buffer_id: excerpt.buffer_id,
1521                excerpt_id: excerpt.id.clone(),
1522                text_anchor,
1523            }
1524        } else if offset == 0 && bias == Bias::Left {
1525            Anchor::min()
1526        } else {
1527            Anchor::max()
1528        }
1529    }
1530
1531    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1532        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1533        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1534        if let Some(excerpt) = cursor.item() {
1535            if excerpt.id == excerpt_id {
1536                let text_anchor = excerpt.clip_anchor(text_anchor);
1537                drop(cursor);
1538                return Anchor {
1539                    buffer_id: excerpt.buffer_id,
1540                    excerpt_id,
1541                    text_anchor,
1542                };
1543            }
1544        }
1545        panic!("excerpt not found");
1546    }
1547
1548    pub fn range_contains_excerpt_boundary<T: ToOffset>(&self, range: Range<T>) -> bool {
1549        let start = range.start.to_offset(self);
1550        let end = range.end.to_offset(self);
1551        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1552        cursor.seek(&start, Bias::Right, &());
1553        let start_id = cursor
1554            .item()
1555            .or_else(|| cursor.prev_item())
1556            .map(|excerpt| &excerpt.id);
1557        cursor.seek_forward(&end, Bias::Right, &());
1558        let end_id = cursor
1559            .item()
1560            .or_else(|| cursor.prev_item())
1561            .map(|excerpt| &excerpt.id);
1562        start_id != end_id
1563    }
1564
1565    pub fn parse_count(&self) -> usize {
1566        self.parse_count
1567    }
1568
1569    pub fn enclosing_bracket_ranges<T: ToOffset>(
1570        &self,
1571        range: Range<T>,
1572    ) -> Option<(Range<usize>, Range<usize>)> {
1573        let range = range.start.to_offset(self)..range.end.to_offset(self);
1574
1575        let mut cursor = self.excerpts.cursor::<usize>();
1576        cursor.seek(&range.start, Bias::Right, &());
1577        let start_excerpt = cursor.item();
1578
1579        cursor.seek(&range.end, Bias::Right, &());
1580        let end_excerpt = cursor.item();
1581
1582        start_excerpt
1583            .zip(end_excerpt)
1584            .and_then(|(start_excerpt, end_excerpt)| {
1585                if start_excerpt.id != end_excerpt.id {
1586                    return None;
1587                }
1588
1589                let excerpt_buffer_start =
1590                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1591                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1592
1593                let start_in_buffer =
1594                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1595                let end_in_buffer =
1596                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1597                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
1598                    .buffer
1599                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
1600
1601                if start_bracket_range.start >= excerpt_buffer_start
1602                    && end_bracket_range.end < excerpt_buffer_end
1603                {
1604                    start_bracket_range.start =
1605                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
1606                    start_bracket_range.end =
1607                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
1608                    end_bracket_range.start =
1609                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
1610                    end_bracket_range.end =
1611                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
1612                    Some((start_bracket_range, end_bracket_range))
1613                } else {
1614                    None
1615                }
1616            })
1617    }
1618
1619    pub fn diagnostics_update_count(&self) -> usize {
1620        self.diagnostics_update_count
1621    }
1622
1623    pub fn language(&self) -> Option<&Arc<Language>> {
1624        self.excerpts
1625            .iter()
1626            .next()
1627            .and_then(|excerpt| excerpt.buffer.language())
1628    }
1629
1630    pub fn is_dirty(&self) -> bool {
1631        self.is_dirty
1632    }
1633
1634    pub fn has_conflict(&self) -> bool {
1635        self.has_conflict
1636    }
1637
1638    pub fn diagnostic_group<'a, O>(
1639        &'a self,
1640        group_id: usize,
1641    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1642    where
1643        O: text::FromAnchor + 'a,
1644    {
1645        self.as_singleton()
1646            .into_iter()
1647            .flat_map(move |buffer| buffer.diagnostic_group(group_id))
1648    }
1649
1650    pub fn diagnostics_in_range<'a, T, O>(
1651        &'a self,
1652        range: Range<T>,
1653    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1654    where
1655        T: 'a + ToOffset,
1656        O: 'a + text::FromAnchor,
1657    {
1658        self.as_singleton().into_iter().flat_map(move |buffer| {
1659            buffer.diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
1660        })
1661    }
1662
1663    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
1664        let range = range.start.to_offset(self)..range.end.to_offset(self);
1665
1666        let mut cursor = self.excerpts.cursor::<usize>();
1667        cursor.seek(&range.start, Bias::Right, &());
1668        let start_excerpt = cursor.item();
1669
1670        cursor.seek(&range.end, Bias::Right, &());
1671        let end_excerpt = cursor.item();
1672
1673        start_excerpt
1674            .zip(end_excerpt)
1675            .and_then(|(start_excerpt, end_excerpt)| {
1676                if start_excerpt.id != end_excerpt.id {
1677                    return None;
1678                }
1679
1680                let excerpt_buffer_start =
1681                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1682                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1683
1684                let start_in_buffer =
1685                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1686                let end_in_buffer =
1687                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1688                let mut ancestor_buffer_range = start_excerpt
1689                    .buffer
1690                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
1691                ancestor_buffer_range.start =
1692                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
1693                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
1694
1695                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
1696                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
1697                Some(start..end)
1698            })
1699    }
1700
1701    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
1702        let buffer = self.as_singleton()?;
1703        let outline = buffer.outline(theme)?;
1704        let excerpt_id = &self.excerpts.iter().next().unwrap().id;
1705        Some(Outline::new(
1706            outline
1707                .items
1708                .into_iter()
1709                .map(|item| OutlineItem {
1710                    depth: item.depth,
1711                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
1712                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
1713                    text: item.text,
1714                    highlight_ranges: item.highlight_ranges,
1715                    name_ranges: item.name_ranges,
1716                })
1717                .collect(),
1718        ))
1719    }
1720
1721    fn buffer_snapshot_for_excerpt<'a>(
1722        &'a self,
1723        excerpt_id: &'a ExcerptId,
1724    ) -> Option<(usize, &'a BufferSnapshot)> {
1725        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1726        cursor.seek(&Some(excerpt_id), Bias::Left, &());
1727        if let Some(excerpt) = cursor.item() {
1728            if excerpt.id == *excerpt_id {
1729                return Some((excerpt.buffer_id, &excerpt.buffer));
1730            }
1731        }
1732        None
1733    }
1734
1735    pub fn remote_selections_in_range<'a>(
1736        &'a self,
1737        range: &'a Range<Anchor>,
1738    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
1739        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1740        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
1741        cursor
1742            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
1743            .flat_map(move |excerpt| {
1744                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
1745                if excerpt.id == range.start.excerpt_id {
1746                    query_range.start = range.start.text_anchor.clone();
1747                }
1748                if excerpt.id == range.end.excerpt_id {
1749                    query_range.end = range.end.text_anchor.clone();
1750                }
1751
1752                excerpt
1753                    .buffer
1754                    .remote_selections_in_range(query_range)
1755                    .flat_map(move |(replica_id, selections)| {
1756                        selections.map(move |selection| {
1757                            let mut start = Anchor {
1758                                buffer_id: excerpt.buffer_id,
1759                                excerpt_id: excerpt.id.clone(),
1760                                text_anchor: selection.start.clone(),
1761                            };
1762                            let mut end = Anchor {
1763                                buffer_id: excerpt.buffer_id,
1764                                excerpt_id: excerpt.id.clone(),
1765                                text_anchor: selection.end.clone(),
1766                            };
1767                            if range.start.cmp(&start, self).unwrap().is_gt() {
1768                                start = range.start.clone();
1769                            }
1770                            if range.end.cmp(&end, self).unwrap().is_lt() {
1771                                end = range.end.clone();
1772                            }
1773
1774                            (
1775                                replica_id,
1776                                Selection {
1777                                    id: selection.id,
1778                                    start,
1779                                    end,
1780                                    reversed: selection.reversed,
1781                                    goal: selection.goal,
1782                                },
1783                            )
1784                        })
1785                    })
1786            })
1787    }
1788}
1789
1790impl History {
1791    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
1792        self.transaction_depth += 1;
1793        if self.transaction_depth == 1 {
1794            let id = post_inc(&mut self.next_transaction_id);
1795            self.undo_stack.push(Transaction {
1796                id,
1797                buffer_transactions: Default::default(),
1798                first_edit_at: now,
1799                last_edit_at: now,
1800            });
1801            Some(id)
1802        } else {
1803            None
1804        }
1805    }
1806
1807    fn end_transaction(
1808        &mut self,
1809        now: Instant,
1810        buffer_transactions: HashSet<(usize, TransactionId)>,
1811    ) -> bool {
1812        assert_ne!(self.transaction_depth, 0);
1813        self.transaction_depth -= 1;
1814        if self.transaction_depth == 0 {
1815            if buffer_transactions.is_empty() {
1816                self.undo_stack.pop();
1817                false
1818            } else {
1819                let transaction = self.undo_stack.last_mut().unwrap();
1820                transaction.last_edit_at = now;
1821                transaction.buffer_transactions.extend(buffer_transactions);
1822                true
1823            }
1824        } else {
1825            false
1826        }
1827    }
1828
1829    fn pop_undo(&mut self) -> Option<&Transaction> {
1830        assert_eq!(self.transaction_depth, 0);
1831        if let Some(transaction) = self.undo_stack.pop() {
1832            self.redo_stack.push(transaction);
1833            self.redo_stack.last()
1834        } else {
1835            None
1836        }
1837    }
1838
1839    fn pop_redo(&mut self) -> Option<&Transaction> {
1840        assert_eq!(self.transaction_depth, 0);
1841        if let Some(transaction) = self.redo_stack.pop() {
1842            self.undo_stack.push(transaction);
1843            self.undo_stack.last()
1844        } else {
1845            None
1846        }
1847    }
1848
1849    fn group(&mut self) -> Option<TransactionId> {
1850        let mut new_len = self.undo_stack.len();
1851        let mut transactions = self.undo_stack.iter_mut();
1852
1853        if let Some(mut transaction) = transactions.next_back() {
1854            while let Some(prev_transaction) = transactions.next_back() {
1855                if transaction.first_edit_at - prev_transaction.last_edit_at <= self.group_interval
1856                {
1857                    transaction = prev_transaction;
1858                    new_len -= 1;
1859                } else {
1860                    break;
1861                }
1862            }
1863        }
1864
1865        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
1866        if let Some(last_transaction) = transactions_to_keep.last_mut() {
1867            if let Some(transaction) = transactions_to_merge.last() {
1868                last_transaction.last_edit_at = transaction.last_edit_at;
1869            }
1870        }
1871
1872        self.undo_stack.truncate(new_len);
1873        self.undo_stack.last().map(|t| t.id)
1874    }
1875}
1876
1877impl Excerpt {
1878    fn new(
1879        id: ExcerptId,
1880        buffer_id: usize,
1881        buffer: BufferSnapshot,
1882        range: Range<text::Anchor>,
1883        has_trailing_newline: bool,
1884    ) -> Self {
1885        Excerpt {
1886            id,
1887            max_buffer_row: range.end.to_point(&buffer).row,
1888            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
1889            buffer_id,
1890            buffer,
1891            range,
1892            has_trailing_newline,
1893        }
1894    }
1895
1896    fn chunks_in_range<'a>(
1897        &'a self,
1898        range: Range<usize>,
1899        theme: Option<&'a SyntaxTheme>,
1900    ) -> ExcerptChunks<'a> {
1901        let content_start = self.range.start.to_offset(&self.buffer);
1902        let chunks_start = content_start + range.start;
1903        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1904
1905        let footer_height = if self.has_trailing_newline
1906            && range.start <= self.text_summary.bytes
1907            && range.end > self.text_summary.bytes
1908        {
1909            1
1910        } else {
1911            0
1912        };
1913
1914        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, theme);
1915
1916        ExcerptChunks {
1917            content_chunks,
1918            footer_height,
1919        }
1920    }
1921
1922    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
1923        let content_start = self.range.start.to_offset(&self.buffer);
1924        let bytes_start = content_start + range.start;
1925        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1926        let footer_height = if self.has_trailing_newline
1927            && range.start <= self.text_summary.bytes
1928            && range.end > self.text_summary.bytes
1929        {
1930            1
1931        } else {
1932            0
1933        };
1934        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
1935
1936        ExcerptBytes {
1937            content_bytes,
1938            footer_height,
1939        }
1940    }
1941
1942    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
1943        if text_anchor
1944            .cmp(&self.range.start, &self.buffer)
1945            .unwrap()
1946            .is_lt()
1947        {
1948            self.range.start.clone()
1949        } else if text_anchor
1950            .cmp(&self.range.end, &self.buffer)
1951            .unwrap()
1952            .is_gt()
1953        {
1954            self.range.end.clone()
1955        } else {
1956            text_anchor
1957        }
1958    }
1959
1960    fn contains(&self, anchor: &Anchor) -> bool {
1961        self.buffer_id == anchor.buffer_id
1962            && self
1963                .range
1964                .start
1965                .cmp(&anchor.text_anchor, &self.buffer)
1966                .unwrap()
1967                .is_le()
1968            && self
1969                .range
1970                .end
1971                .cmp(&anchor.text_anchor, &self.buffer)
1972                .unwrap()
1973                .is_ge()
1974    }
1975}
1976
1977impl fmt::Debug for Excerpt {
1978    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1979        f.debug_struct("Excerpt")
1980            .field("id", &self.id)
1981            .field("buffer_id", &self.buffer_id)
1982            .field("range", &self.range)
1983            .field("text_summary", &self.text_summary)
1984            .field("has_trailing_newline", &self.has_trailing_newline)
1985            .finish()
1986    }
1987}
1988
1989impl sum_tree::Item for Excerpt {
1990    type Summary = ExcerptSummary;
1991
1992    fn summary(&self) -> Self::Summary {
1993        let mut text = self.text_summary.clone();
1994        if self.has_trailing_newline {
1995            text += TextSummary::from("\n");
1996        }
1997        ExcerptSummary {
1998            excerpt_id: self.id.clone(),
1999            max_buffer_row: self.max_buffer_row,
2000            text,
2001        }
2002    }
2003}
2004
2005impl sum_tree::Summary for ExcerptSummary {
2006    type Context = ();
2007
2008    fn add_summary(&mut self, summary: &Self, _: &()) {
2009        debug_assert!(summary.excerpt_id > self.excerpt_id);
2010        self.excerpt_id = summary.excerpt_id.clone();
2011        self.text.add_summary(&summary.text, &());
2012        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2013    }
2014}
2015
2016impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2017    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2018        *self += &summary.text;
2019    }
2020}
2021
2022impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2023    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2024        *self += summary.text.bytes;
2025    }
2026}
2027
2028impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2029    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2030        Ord::cmp(self, &cursor_location.text.bytes)
2031    }
2032}
2033
2034impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2035    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2036        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2037    }
2038}
2039
2040impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2041    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2042        *self += summary.text.lines;
2043    }
2044}
2045
2046impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2047    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2048        *self += summary.text.lines_utf16
2049    }
2050}
2051
2052impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2053    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2054        *self = Some(&summary.excerpt_id);
2055    }
2056}
2057
2058impl<'a> MultiBufferRows<'a> {
2059    pub fn seek(&mut self, row: u32) {
2060        self.buffer_row_range = 0..0;
2061
2062        self.excerpts
2063            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2064        if self.excerpts.item().is_none() {
2065            self.excerpts.prev(&());
2066
2067            if self.excerpts.item().is_none() && row == 0 {
2068                self.buffer_row_range = 0..1;
2069                return;
2070            }
2071        }
2072
2073        if let Some(excerpt) = self.excerpts.item() {
2074            let overshoot = row - self.excerpts.start().row;
2075            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2076            self.buffer_row_range.start = excerpt_start + overshoot;
2077            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2078        }
2079    }
2080}
2081
2082impl<'a> Iterator for MultiBufferRows<'a> {
2083    type Item = Option<u32>;
2084
2085    fn next(&mut self) -> Option<Self::Item> {
2086        loop {
2087            if !self.buffer_row_range.is_empty() {
2088                let row = Some(self.buffer_row_range.start);
2089                self.buffer_row_range.start += 1;
2090                return Some(row);
2091            }
2092            self.excerpts.item()?;
2093            self.excerpts.next(&());
2094            let excerpt = self.excerpts.item()?;
2095            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2096            self.buffer_row_range.end =
2097                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2098        }
2099    }
2100}
2101
2102impl<'a> MultiBufferChunks<'a> {
2103    pub fn offset(&self) -> usize {
2104        self.range.start
2105    }
2106
2107    pub fn seek(&mut self, offset: usize) {
2108        self.range.start = offset;
2109        self.excerpts.seek(&offset, Bias::Right, &());
2110        if let Some(excerpt) = self.excerpts.item() {
2111            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2112                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2113                self.theme,
2114            ));
2115        } else {
2116            self.excerpt_chunks = None;
2117        }
2118    }
2119}
2120
2121impl<'a> Iterator for MultiBufferChunks<'a> {
2122    type Item = Chunk<'a>;
2123
2124    fn next(&mut self) -> Option<Self::Item> {
2125        if self.range.is_empty() {
2126            None
2127        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2128            self.range.start += chunk.text.len();
2129            Some(chunk)
2130        } else {
2131            self.excerpts.next(&());
2132            let excerpt = self.excerpts.item()?;
2133            self.excerpt_chunks = Some(
2134                excerpt.chunks_in_range(0..self.range.end - self.excerpts.start(), self.theme),
2135            );
2136            self.next()
2137        }
2138    }
2139}
2140
2141impl<'a> MultiBufferBytes<'a> {
2142    fn consume(&mut self, len: usize) {
2143        self.range.start += len;
2144        self.chunk = &self.chunk[len..];
2145
2146        if !self.range.is_empty() && self.chunk.is_empty() {
2147            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2148                self.chunk = chunk;
2149            } else {
2150                self.excerpts.next(&());
2151                if let Some(excerpt) = self.excerpts.item() {
2152                    let mut excerpt_bytes =
2153                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2154                    self.chunk = excerpt_bytes.next().unwrap();
2155                    self.excerpt_bytes = Some(excerpt_bytes);
2156                }
2157            }
2158        }
2159    }
2160}
2161
2162impl<'a> Iterator for MultiBufferBytes<'a> {
2163    type Item = &'a [u8];
2164
2165    fn next(&mut self) -> Option<Self::Item> {
2166        let chunk = self.chunk;
2167        if chunk.is_empty() {
2168            None
2169        } else {
2170            self.consume(chunk.len());
2171            Some(chunk)
2172        }
2173    }
2174}
2175
2176impl<'a> io::Read for MultiBufferBytes<'a> {
2177    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2178        let len = cmp::min(buf.len(), self.chunk.len());
2179        buf[..len].copy_from_slice(&self.chunk[..len]);
2180        if len > 0 {
2181            self.consume(len);
2182        }
2183        Ok(len)
2184    }
2185}
2186
2187impl<'a> Iterator for ExcerptBytes<'a> {
2188    type Item = &'a [u8];
2189
2190    fn next(&mut self) -> Option<Self::Item> {
2191        if let Some(chunk) = self.content_bytes.next() {
2192            if !chunk.is_empty() {
2193                return Some(chunk);
2194            }
2195        }
2196
2197        if self.footer_height > 0 {
2198            let result = &NEWLINES[..self.footer_height];
2199            self.footer_height = 0;
2200            return Some(result);
2201        }
2202
2203        None
2204    }
2205}
2206
2207impl<'a> Iterator for ExcerptChunks<'a> {
2208    type Item = Chunk<'a>;
2209
2210    fn next(&mut self) -> Option<Self::Item> {
2211        if let Some(chunk) = self.content_chunks.next() {
2212            return Some(chunk);
2213        }
2214
2215        if self.footer_height > 0 {
2216            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2217            self.footer_height = 0;
2218            return Some(Chunk {
2219                text,
2220                ..Default::default()
2221            });
2222        }
2223
2224        None
2225    }
2226}
2227
2228impl ToOffset for Point {
2229    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2230        snapshot.point_to_offset(*self)
2231    }
2232}
2233
2234impl ToOffset for PointUtf16 {
2235    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2236        snapshot.point_utf16_to_offset(*self)
2237    }
2238}
2239
2240impl ToOffset for usize {
2241    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2242        assert!(*self <= snapshot.len(), "offset is out of range");
2243        *self
2244    }
2245}
2246
2247impl ToPoint for usize {
2248    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2249        snapshot.offset_to_point(*self)
2250    }
2251}
2252
2253impl ToPoint for Point {
2254    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2255        *self
2256    }
2257}
2258
2259#[cfg(test)]
2260mod tests {
2261    use super::*;
2262    use gpui::MutableAppContext;
2263    use language::{Buffer, Rope};
2264    use rand::prelude::*;
2265    use std::env;
2266    use text::{Point, RandomCharIter};
2267    use util::test::sample_text;
2268
2269    #[gpui::test]
2270    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2271        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2272        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2273
2274        let snapshot = multibuffer.read(cx).snapshot(cx);
2275        assert_eq!(snapshot.text(), buffer.read(cx).text());
2276
2277        assert_eq!(
2278            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2279            (0..buffer.read(cx).row_count())
2280                .map(Some)
2281                .collect::<Vec<_>>()
2282        );
2283
2284        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2285        let snapshot = multibuffer.read(cx).snapshot(cx);
2286
2287        assert_eq!(snapshot.text(), buffer.read(cx).text());
2288        assert_eq!(
2289            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2290            (0..buffer.read(cx).row_count())
2291                .map(Some)
2292                .collect::<Vec<_>>()
2293        );
2294    }
2295
2296    #[gpui::test]
2297    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2298        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2299        let guest_buffer = cx.add_model(|cx| {
2300            let message = host_buffer.read(cx).to_proto();
2301            Buffer::from_proto(1, message, None, cx).unwrap()
2302        });
2303        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2304        let snapshot = multibuffer.read(cx).snapshot(cx);
2305        assert_eq!(snapshot.text(), "a");
2306
2307        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2308        let snapshot = multibuffer.read(cx).snapshot(cx);
2309        assert_eq!(snapshot.text(), "ab");
2310
2311        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2312        let snapshot = multibuffer.read(cx).snapshot(cx);
2313        assert_eq!(snapshot.text(), "abc");
2314    }
2315
2316    #[gpui::test]
2317    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2318        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2319        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2320        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2321
2322        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2323            let subscription = multibuffer.subscribe();
2324            multibuffer.push_excerpt(
2325                ExcerptProperties {
2326                    buffer: &buffer_1,
2327                    range: Point::new(1, 2)..Point::new(2, 5),
2328                },
2329                cx,
2330            );
2331            assert_eq!(
2332                subscription.consume().into_inner(),
2333                [Edit {
2334                    old: 0..0,
2335                    new: 0..10
2336                }]
2337            );
2338
2339            multibuffer.push_excerpt(
2340                ExcerptProperties {
2341                    buffer: &buffer_1,
2342                    range: Point::new(3, 3)..Point::new(4, 4),
2343                },
2344                cx,
2345            );
2346            multibuffer.push_excerpt(
2347                ExcerptProperties {
2348                    buffer: &buffer_2,
2349                    range: Point::new(3, 1)..Point::new(3, 3),
2350                },
2351                cx,
2352            );
2353            assert_eq!(
2354                subscription.consume().into_inner(),
2355                [Edit {
2356                    old: 10..10,
2357                    new: 10..22
2358                }]
2359            );
2360
2361            subscription
2362        });
2363
2364        let snapshot = multibuffer.read(cx).snapshot(cx);
2365        assert_eq!(
2366            snapshot.text(),
2367            concat!(
2368                "bbbb\n",  // Preserve newlines
2369                "ccccc\n", //
2370                "ddd\n",   //
2371                "eeee\n",  //
2372                "jj"       //
2373            )
2374        );
2375        assert_eq!(
2376            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2377            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2378        );
2379        assert_eq!(
2380            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2381            [Some(3), Some(4), Some(3)]
2382        );
2383        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2384        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2385        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(1, 5)));
2386        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(2, 0)));
2387        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(4, 0)));
2388        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(2, 0)..Point::new(3, 0)));
2389        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 0)..Point::new(4, 2)));
2390        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 2)..Point::new(4, 2)));
2391
2392        buffer_1.update(cx, |buffer, cx| {
2393            buffer.edit(
2394                [
2395                    Point::new(0, 0)..Point::new(0, 0),
2396                    Point::new(2, 1)..Point::new(2, 3),
2397                ],
2398                "\n",
2399                cx,
2400            );
2401        });
2402
2403        let snapshot = multibuffer.read(cx).snapshot(cx);
2404        assert_eq!(
2405            snapshot.text(),
2406            concat!(
2407                "bbbb\n", // Preserve newlines
2408                "c\n",    //
2409                "cc\n",   //
2410                "ddd\n",  //
2411                "eeee\n", //
2412                "jj"      //
2413            )
2414        );
2415
2416        assert_eq!(
2417            subscription.consume().into_inner(),
2418            [Edit {
2419                old: 6..8,
2420                new: 6..7
2421            }]
2422        );
2423
2424        let snapshot = multibuffer.read(cx).snapshot(cx);
2425        assert_eq!(
2426            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2427            Point::new(0, 4)
2428        );
2429        assert_eq!(
2430            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2431            Point::new(0, 4)
2432        );
2433        assert_eq!(
2434            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2435            Point::new(5, 1)
2436        );
2437        assert_eq!(
2438            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2439            Point::new(5, 2)
2440        );
2441        assert_eq!(
2442            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2443            Point::new(5, 2)
2444        );
2445
2446        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2447            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2448            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2449            multibuffer.snapshot(cx)
2450        });
2451
2452        assert_eq!(
2453            snapshot.text(),
2454            concat!(
2455                "bbbb\n", // Preserve newlines
2456                "c\n",    //
2457                "cc\n",   //
2458                "ddd\n",  //
2459                "eeee",   //
2460            )
2461        );
2462    }
2463
2464    #[gpui::test]
2465    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
2466        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2467
2468        let snapshot = multibuffer.read(cx).snapshot(cx);
2469        assert_eq!(snapshot.text(), "");
2470        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
2471        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
2472    }
2473
2474    #[gpui::test]
2475    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
2476        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2477        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2478        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2479        buffer.update(cx, |buffer, cx| {
2480            buffer.edit([0..0], "X", cx);
2481            buffer.edit([5..5], "Y", cx);
2482        });
2483        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2484
2485        assert_eq!(old_snapshot.text(), "abcd");
2486        assert_eq!(new_snapshot.text(), "XabcdY");
2487
2488        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2489        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2490        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
2491        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
2492    }
2493
2494    #[gpui::test]
2495    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
2496        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2497        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
2498        let multibuffer = cx.add_model(|cx| {
2499            let mut multibuffer = MultiBuffer::new(0);
2500            multibuffer.push_excerpt(
2501                ExcerptProperties {
2502                    buffer: &buffer_1,
2503                    range: 0..4,
2504                },
2505                cx,
2506            );
2507            multibuffer.push_excerpt(
2508                ExcerptProperties {
2509                    buffer: &buffer_2,
2510                    range: 0..5,
2511                },
2512                cx,
2513            );
2514            multibuffer
2515        });
2516        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2517
2518        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
2519        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
2520        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2521        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2522        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2523        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2524
2525        buffer_1.update(cx, |buffer, cx| {
2526            buffer.edit([0..0], "W", cx);
2527            buffer.edit([5..5], "X", cx);
2528        });
2529        buffer_2.update(cx, |buffer, cx| {
2530            buffer.edit([0..0], "Y", cx);
2531            buffer.edit([6..0], "Z", cx);
2532        });
2533        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2534
2535        assert_eq!(old_snapshot.text(), "abcd\nefghi");
2536        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
2537
2538        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2539        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2540        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
2541        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
2542        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
2543        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
2544        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
2545        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
2546        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
2547        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
2548    }
2549
2550    #[gpui::test]
2551    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
2552        cx: &mut MutableAppContext,
2553    ) {
2554        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2555        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
2556        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2557
2558        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
2559        // Add an excerpt from buffer 1 that spans this new insertion.
2560        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
2561        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
2562            multibuffer.push_excerpt(
2563                ExcerptProperties {
2564                    buffer: &buffer_1,
2565                    range: 0..7,
2566                },
2567                cx,
2568            )
2569        });
2570
2571        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
2572        assert_eq!(snapshot_1.text(), "abcd123");
2573
2574        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
2575        let (excerpt_id_2, excerpt_id_3, _) = multibuffer.update(cx, |multibuffer, cx| {
2576            multibuffer.remove_excerpts([&excerpt_id_1], cx);
2577            (
2578                multibuffer.push_excerpt(
2579                    ExcerptProperties {
2580                        buffer: &buffer_2,
2581                        range: 0..4,
2582                    },
2583                    cx,
2584                ),
2585                multibuffer.push_excerpt(
2586                    ExcerptProperties {
2587                        buffer: &buffer_2,
2588                        range: 6..10,
2589                    },
2590                    cx,
2591                ),
2592                multibuffer.push_excerpt(
2593                    ExcerptProperties {
2594                        buffer: &buffer_2,
2595                        range: 12..16,
2596                    },
2597                    cx,
2598                ),
2599            )
2600        });
2601        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
2602        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
2603
2604        // The old excerpt id has been reused.
2605        assert_eq!(excerpt_id_2, excerpt_id_1);
2606
2607        // Resolve some anchors from the previous snapshot in the new snapshot.
2608        // Although there is still an excerpt with the same id, it is for
2609        // a different buffer, so we don't attempt to resolve the old text
2610        // anchor in the new buffer.
2611        assert_eq!(
2612            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
2613            0
2614        );
2615        assert_eq!(
2616            snapshot_2.summaries_for_anchors::<usize, _>(&[
2617                snapshot_1.anchor_before(2),
2618                snapshot_1.anchor_after(3)
2619            ]),
2620            vec![0, 0]
2621        );
2622        let refresh =
2623            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
2624        assert_eq!(
2625            refresh,
2626            &[
2627                (0, snapshot_2.anchor_before(0), false),
2628                (1, snapshot_2.anchor_after(0), false),
2629            ]
2630        );
2631
2632        // Replace the middle excerpt with a smaller excerpt in buffer 2,
2633        // that intersects the old excerpt.
2634        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
2635            multibuffer.remove_excerpts([&excerpt_id_3], cx);
2636            multibuffer.insert_excerpt_after(
2637                &excerpt_id_3,
2638                ExcerptProperties {
2639                    buffer: &buffer_2,
2640                    range: 5..8,
2641                },
2642                cx,
2643            )
2644        });
2645
2646        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
2647        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
2648        assert_ne!(excerpt_id_5, excerpt_id_3);
2649
2650        // Resolve some anchors from the previous snapshot in the new snapshot.
2651        // The anchor in the middle excerpt snaps to the beginning of the
2652        // excerpt, since it is not
2653        let anchors = [
2654            snapshot_2.anchor_before(0),
2655            snapshot_2.anchor_after(2),
2656            snapshot_2.anchor_after(6),
2657            snapshot_2.anchor_after(14),
2658        ];
2659        assert_eq!(
2660            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
2661            &[0, 2, 9, 13]
2662        );
2663
2664        let new_anchors = snapshot_3.refresh_anchors(&anchors);
2665        assert_eq!(
2666            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
2667            &[(0, true), (1, true), (2, true), (3, true)]
2668        );
2669        assert_eq!(
2670            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
2671            &[0, 2, 7, 13]
2672        );
2673    }
2674
2675    #[gpui::test(iterations = 100)]
2676    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
2677        let operations = env::var("OPERATIONS")
2678            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2679            .unwrap_or(10);
2680
2681        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
2682        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2683        let mut excerpt_ids = Vec::new();
2684        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
2685        let mut anchors = Vec::new();
2686        let mut old_versions = Vec::new();
2687
2688        for _ in 0..operations {
2689            match rng.gen_range(0..100) {
2690                0..=19 if !buffers.is_empty() => {
2691                    let buffer = buffers.choose(&mut rng).unwrap();
2692                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
2693                }
2694                20..=29 if !expected_excerpts.is_empty() => {
2695                    let mut ids_to_remove = vec![];
2696                    for _ in 0..rng.gen_range(1..=3) {
2697                        if expected_excerpts.is_empty() {
2698                            break;
2699                        }
2700
2701                        let ix = rng.gen_range(0..expected_excerpts.len());
2702                        ids_to_remove.push(excerpt_ids.remove(ix));
2703                        let (buffer, range) = expected_excerpts.remove(ix);
2704                        let buffer = buffer.read(cx);
2705                        log::info!(
2706                            "Removing excerpt {}: {:?}",
2707                            ix,
2708                            buffer
2709                                .text_for_range(range.to_offset(&buffer))
2710                                .collect::<String>(),
2711                        );
2712                    }
2713                    ids_to_remove.sort_unstable();
2714                    multibuffer.update(cx, |multibuffer, cx| {
2715                        multibuffer.remove_excerpts(&ids_to_remove, cx)
2716                    });
2717                }
2718                30..=39 if !expected_excerpts.is_empty() => {
2719                    let multibuffer = multibuffer.read(cx).read(cx);
2720                    let offset =
2721                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
2722                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
2723                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
2724                    anchors.push(multibuffer.anchor_at(offset, bias));
2725                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
2726                }
2727                40..=44 if !anchors.is_empty() => {
2728                    let multibuffer = multibuffer.read(cx).read(cx);
2729                    anchors = multibuffer
2730                        .refresh_anchors(&anchors)
2731                        .into_iter()
2732                        .map(|a| a.1)
2733                        .collect();
2734                }
2735                _ => {
2736                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
2737                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
2738                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
2739                        buffers.last().unwrap()
2740                    } else {
2741                        buffers.choose(&mut rng).unwrap()
2742                    };
2743
2744                    let buffer = buffer_handle.read(cx);
2745                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2746                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2747                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
2748                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
2749                    let prev_excerpt_id = excerpt_ids
2750                        .get(prev_excerpt_ix)
2751                        .cloned()
2752                        .unwrap_or(ExcerptId::max());
2753                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
2754
2755                    log::info!(
2756                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
2757                        excerpt_ix,
2758                        expected_excerpts.len(),
2759                        buffer_handle.id(),
2760                        buffer.text(),
2761                        start_ix..end_ix,
2762                        &buffer.text()[start_ix..end_ix]
2763                    );
2764
2765                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
2766                        multibuffer.insert_excerpt_after(
2767                            &prev_excerpt_id,
2768                            ExcerptProperties {
2769                                buffer: &buffer_handle,
2770                                range: start_ix..end_ix,
2771                            },
2772                            cx,
2773                        )
2774                    });
2775
2776                    excerpt_ids.insert(excerpt_ix, excerpt_id);
2777                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
2778                }
2779            }
2780
2781            if rng.gen_bool(0.3) {
2782                multibuffer.update(cx, |multibuffer, cx| {
2783                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
2784                })
2785            }
2786
2787            let snapshot = multibuffer.read(cx).snapshot(cx);
2788
2789            let mut excerpt_starts = Vec::new();
2790            let mut expected_text = String::new();
2791            let mut expected_buffer_rows = Vec::new();
2792            for (buffer, range) in &expected_excerpts {
2793                let buffer = buffer.read(cx);
2794                let buffer_range = range.to_offset(buffer);
2795
2796                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
2797                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
2798                expected_text.push('\n');
2799
2800                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
2801                    ..=buffer.offset_to_point(buffer_range.end).row;
2802                for row in buffer_row_range {
2803                    expected_buffer_rows.push(Some(row));
2804                }
2805            }
2806            // Remove final trailing newline.
2807            if !expected_excerpts.is_empty() {
2808                expected_text.pop();
2809            }
2810
2811            // Always report one buffer row
2812            if expected_buffer_rows.is_empty() {
2813                expected_buffer_rows.push(Some(0));
2814            }
2815
2816            assert_eq!(snapshot.text(), expected_text);
2817            log::info!("MultiBuffer text: {:?}", expected_text);
2818
2819            assert_eq!(
2820                snapshot.buffer_rows(0).collect::<Vec<_>>(),
2821                expected_buffer_rows,
2822            );
2823
2824            for _ in 0..5 {
2825                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
2826                assert_eq!(
2827                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
2828                    &expected_buffer_rows[start_row..],
2829                    "buffer_rows({})",
2830                    start_row
2831                );
2832            }
2833
2834            assert_eq!(
2835                snapshot.max_buffer_row(),
2836                expected_buffer_rows
2837                    .into_iter()
2838                    .filter_map(|r| r)
2839                    .max()
2840                    .unwrap()
2841            );
2842
2843            let mut excerpt_starts = excerpt_starts.into_iter();
2844            for (buffer, range) in &expected_excerpts {
2845                let buffer_id = buffer.id();
2846                let buffer = buffer.read(cx);
2847                let buffer_range = range.to_offset(buffer);
2848                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
2849                let buffer_start_point_utf16 =
2850                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
2851
2852                let excerpt_start = excerpt_starts.next().unwrap();
2853                let mut offset = excerpt_start.bytes;
2854                let mut buffer_offset = buffer_range.start;
2855                let mut point = excerpt_start.lines;
2856                let mut buffer_point = buffer_start_point;
2857                let mut point_utf16 = excerpt_start.lines_utf16;
2858                let mut buffer_point_utf16 = buffer_start_point_utf16;
2859                for ch in buffer
2860                    .snapshot()
2861                    .chunks(buffer_range.clone(), None)
2862                    .flat_map(|c| c.text.chars())
2863                {
2864                    for _ in 0..ch.len_utf8() {
2865                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
2866                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
2867                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
2868                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
2869                        assert_eq!(
2870                            left_offset,
2871                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
2872                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
2873                            offset,
2874                            buffer_id,
2875                            buffer_offset,
2876                        );
2877                        assert_eq!(
2878                            right_offset,
2879                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
2880                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
2881                            offset,
2882                            buffer_id,
2883                            buffer_offset,
2884                        );
2885
2886                        let left_point = snapshot.clip_point(point, Bias::Left);
2887                        let right_point = snapshot.clip_point(point, Bias::Right);
2888                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
2889                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
2890                        assert_eq!(
2891                            left_point,
2892                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
2893                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
2894                            point,
2895                            buffer_id,
2896                            buffer_point,
2897                        );
2898                        assert_eq!(
2899                            right_point,
2900                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
2901                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
2902                            point,
2903                            buffer_id,
2904                            buffer_point,
2905                        );
2906
2907                        assert_eq!(
2908                            snapshot.point_to_offset(left_point),
2909                            left_offset,
2910                            "point_to_offset({:?})",
2911                            left_point,
2912                        );
2913                        assert_eq!(
2914                            snapshot.offset_to_point(left_offset),
2915                            left_point,
2916                            "offset_to_point({:?})",
2917                            left_offset,
2918                        );
2919
2920                        offset += 1;
2921                        buffer_offset += 1;
2922                        if ch == '\n' {
2923                            point += Point::new(1, 0);
2924                            buffer_point += Point::new(1, 0);
2925                        } else {
2926                            point += Point::new(0, 1);
2927                            buffer_point += Point::new(0, 1);
2928                        }
2929                    }
2930
2931                    for _ in 0..ch.len_utf16() {
2932                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
2933                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
2934                        let buffer_left_point_utf16 =
2935                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
2936                        let buffer_right_point_utf16 =
2937                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
2938                        assert_eq!(
2939                            left_point_utf16,
2940                            excerpt_start.lines_utf16
2941                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
2942                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
2943                            point_utf16,
2944                            buffer_id,
2945                            buffer_point_utf16,
2946                        );
2947                        assert_eq!(
2948                            right_point_utf16,
2949                            excerpt_start.lines_utf16
2950                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
2951                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
2952                            point_utf16,
2953                            buffer_id,
2954                            buffer_point_utf16,
2955                        );
2956
2957                        if ch == '\n' {
2958                            point_utf16 += PointUtf16::new(1, 0);
2959                            buffer_point_utf16 += PointUtf16::new(1, 0);
2960                        } else {
2961                            point_utf16 += PointUtf16::new(0, 1);
2962                            buffer_point_utf16 += PointUtf16::new(0, 1);
2963                        }
2964                    }
2965                }
2966            }
2967
2968            for (row, line) in expected_text.split('\n').enumerate() {
2969                assert_eq!(
2970                    snapshot.line_len(row as u32),
2971                    line.len() as u32,
2972                    "line_len({}).",
2973                    row
2974                );
2975            }
2976
2977            let text_rope = Rope::from(expected_text.as_str());
2978            for _ in 0..10 {
2979                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
2980                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2981
2982                let text_for_range = snapshot
2983                    .text_for_range(start_ix..end_ix)
2984                    .collect::<String>();
2985                assert_eq!(
2986                    text_for_range,
2987                    &expected_text[start_ix..end_ix],
2988                    "incorrect text for range {:?}",
2989                    start_ix..end_ix
2990                );
2991
2992                let excerpted_buffer_ranges =
2993                    multibuffer.read(cx).excerpted_buffers(start_ix..end_ix, cx);
2994                let excerpted_buffers_text = excerpted_buffer_ranges
2995                    .into_iter()
2996                    .map(|(buffer, buffer_range)| {
2997                        buffer
2998                            .read(cx)
2999                            .text_for_range(buffer_range)
3000                            .collect::<String>()
3001                    })
3002                    .collect::<Vec<_>>()
3003                    .join("\n");
3004                assert_eq!(excerpted_buffers_text, text_for_range);
3005
3006                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3007                assert_eq!(
3008                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3009                    expected_summary,
3010                    "incorrect summary for range {:?}",
3011                    start_ix..end_ix
3012                );
3013            }
3014
3015            // Anchor resolution
3016            for (anchor, resolved_offset) in anchors
3017                .iter()
3018                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3019            {
3020                assert_eq!(
3021                    snapshot.summary_for_anchor::<usize>(anchor),
3022                    resolved_offset
3023                );
3024            }
3025
3026            for _ in 0..10 {
3027                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3028                assert_eq!(
3029                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3030                    expected_text[..end_ix].chars().rev().collect::<String>(),
3031                );
3032            }
3033
3034            for _ in 0..10 {
3035                let end_ix = rng.gen_range(0..=text_rope.len());
3036                let start_ix = rng.gen_range(0..=end_ix);
3037                assert_eq!(
3038                    snapshot
3039                        .bytes_in_range(start_ix..end_ix)
3040                        .flatten()
3041                        .copied()
3042                        .collect::<Vec<_>>(),
3043                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3044                    "bytes_in_range({:?})",
3045                    start_ix..end_ix,
3046                );
3047            }
3048        }
3049
3050        let snapshot = multibuffer.read(cx).snapshot(cx);
3051        for (old_snapshot, subscription) in old_versions {
3052            let edits = subscription.consume().into_inner();
3053
3054            log::info!(
3055                "applying subscription edits to old text: {:?}: {:?}",
3056                old_snapshot.text(),
3057                edits,
3058            );
3059
3060            let mut text = old_snapshot.text();
3061            for edit in edits {
3062                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3063                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3064            }
3065            assert_eq!(text.to_string(), snapshot.text());
3066        }
3067    }
3068
3069    #[gpui::test]
3070    fn test_history(cx: &mut MutableAppContext) {
3071        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3072        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3073        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3074        let group_interval = multibuffer.read(cx).history.group_interval;
3075        multibuffer.update(cx, |multibuffer, cx| {
3076            multibuffer.push_excerpt(
3077                ExcerptProperties {
3078                    buffer: &buffer_1,
3079                    range: 0..buffer_1.read(cx).len(),
3080                },
3081                cx,
3082            );
3083            multibuffer.push_excerpt(
3084                ExcerptProperties {
3085                    buffer: &buffer_2,
3086                    range: 0..buffer_2.read(cx).len(),
3087                },
3088                cx,
3089            );
3090        });
3091
3092        let mut now = Instant::now();
3093
3094        multibuffer.update(cx, |multibuffer, cx| {
3095            multibuffer.start_transaction_at(now, cx);
3096            multibuffer.edit(
3097                [
3098                    Point::new(0, 0)..Point::new(0, 0),
3099                    Point::new(1, 0)..Point::new(1, 0),
3100                ],
3101                "A",
3102                cx,
3103            );
3104            multibuffer.edit(
3105                [
3106                    Point::new(0, 1)..Point::new(0, 1),
3107                    Point::new(1, 1)..Point::new(1, 1),
3108                ],
3109                "B",
3110                cx,
3111            );
3112            multibuffer.end_transaction_at(now, cx);
3113            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3114
3115            now += 2 * group_interval;
3116            multibuffer.start_transaction_at(now, cx);
3117            multibuffer.edit([2..2], "C", cx);
3118            multibuffer.end_transaction_at(now, cx);
3119            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3120
3121            multibuffer.undo(cx);
3122            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3123
3124            multibuffer.undo(cx);
3125            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3126
3127            multibuffer.redo(cx);
3128            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3129
3130            multibuffer.redo(cx);
3131            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3132
3133            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3134            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3135
3136            multibuffer.undo(cx);
3137            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3138
3139            multibuffer.redo(cx);
3140            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3141
3142            multibuffer.redo(cx);
3143            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3144
3145            multibuffer.undo(cx);
3146            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3147
3148            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3149            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3150
3151            multibuffer.undo(cx);
3152            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3153        });
3154    }
3155}