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 can_resolve(&self, anchor: &Anchor) -> bool {
1549        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
1550            true
1551        } else if let Some((buffer_id, buffer_snapshot)) =
1552            self.buffer_snapshot_for_excerpt(&anchor.excerpt_id)
1553        {
1554            anchor.buffer_id == buffer_id && buffer_snapshot.can_resolve(&anchor.text_anchor)
1555        } else {
1556            false
1557        }
1558    }
1559
1560    pub fn range_contains_excerpt_boundary<T: ToOffset>(&self, range: Range<T>) -> bool {
1561        let start = range.start.to_offset(self);
1562        let end = range.end.to_offset(self);
1563        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1564        cursor.seek(&start, Bias::Right, &());
1565        let start_id = cursor
1566            .item()
1567            .or_else(|| cursor.prev_item())
1568            .map(|excerpt| &excerpt.id);
1569        cursor.seek_forward(&end, Bias::Right, &());
1570        let end_id = cursor
1571            .item()
1572            .or_else(|| cursor.prev_item())
1573            .map(|excerpt| &excerpt.id);
1574        start_id != end_id
1575    }
1576
1577    pub fn parse_count(&self) -> usize {
1578        self.parse_count
1579    }
1580
1581    pub fn enclosing_bracket_ranges<T: ToOffset>(
1582        &self,
1583        range: Range<T>,
1584    ) -> Option<(Range<usize>, Range<usize>)> {
1585        let range = range.start.to_offset(self)..range.end.to_offset(self);
1586
1587        let mut cursor = self.excerpts.cursor::<usize>();
1588        cursor.seek(&range.start, Bias::Right, &());
1589        let start_excerpt = cursor.item();
1590
1591        cursor.seek(&range.end, Bias::Right, &());
1592        let end_excerpt = cursor.item();
1593
1594        start_excerpt
1595            .zip(end_excerpt)
1596            .and_then(|(start_excerpt, end_excerpt)| {
1597                if start_excerpt.id != end_excerpt.id {
1598                    return None;
1599                }
1600
1601                let excerpt_buffer_start =
1602                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1603                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1604
1605                let start_in_buffer =
1606                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1607                let end_in_buffer =
1608                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1609                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
1610                    .buffer
1611                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
1612
1613                if start_bracket_range.start >= excerpt_buffer_start
1614                    && end_bracket_range.end < excerpt_buffer_end
1615                {
1616                    start_bracket_range.start =
1617                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
1618                    start_bracket_range.end =
1619                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
1620                    end_bracket_range.start =
1621                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
1622                    end_bracket_range.end =
1623                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
1624                    Some((start_bracket_range, end_bracket_range))
1625                } else {
1626                    None
1627                }
1628            })
1629    }
1630
1631    pub fn diagnostics_update_count(&self) -> usize {
1632        self.diagnostics_update_count
1633    }
1634
1635    pub fn language(&self) -> Option<&Arc<Language>> {
1636        self.excerpts
1637            .iter()
1638            .next()
1639            .and_then(|excerpt| excerpt.buffer.language())
1640    }
1641
1642    pub fn is_dirty(&self) -> bool {
1643        self.is_dirty
1644    }
1645
1646    pub fn has_conflict(&self) -> bool {
1647        self.has_conflict
1648    }
1649
1650    pub fn diagnostic_group<'a, O>(
1651        &'a self,
1652        group_id: usize,
1653    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1654    where
1655        O: text::FromAnchor + 'a,
1656    {
1657        self.as_singleton()
1658            .into_iter()
1659            .flat_map(move |buffer| buffer.diagnostic_group(group_id))
1660    }
1661
1662    pub fn diagnostics_in_range<'a, T, O>(
1663        &'a self,
1664        range: Range<T>,
1665    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1666    where
1667        T: 'a + ToOffset,
1668        O: 'a + text::FromAnchor,
1669    {
1670        self.as_singleton().into_iter().flat_map(move |buffer| {
1671            buffer.diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
1672        })
1673    }
1674
1675    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
1676        let range = range.start.to_offset(self)..range.end.to_offset(self);
1677
1678        let mut cursor = self.excerpts.cursor::<usize>();
1679        cursor.seek(&range.start, Bias::Right, &());
1680        let start_excerpt = cursor.item();
1681
1682        cursor.seek(&range.end, Bias::Right, &());
1683        let end_excerpt = cursor.item();
1684
1685        start_excerpt
1686            .zip(end_excerpt)
1687            .and_then(|(start_excerpt, end_excerpt)| {
1688                if start_excerpt.id != end_excerpt.id {
1689                    return None;
1690                }
1691
1692                let excerpt_buffer_start =
1693                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1694                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1695
1696                let start_in_buffer =
1697                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1698                let end_in_buffer =
1699                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1700                let mut ancestor_buffer_range = start_excerpt
1701                    .buffer
1702                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
1703                ancestor_buffer_range.start =
1704                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
1705                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
1706
1707                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
1708                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
1709                Some(start..end)
1710            })
1711    }
1712
1713    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
1714        let buffer = self.as_singleton()?;
1715        let outline = buffer.outline(theme)?;
1716        let excerpt_id = &self.excerpts.iter().next().unwrap().id;
1717        Some(Outline::new(
1718            outline
1719                .items
1720                .into_iter()
1721                .map(|item| OutlineItem {
1722                    depth: item.depth,
1723                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
1724                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
1725                    text: item.text,
1726                    highlight_ranges: item.highlight_ranges,
1727                    name_ranges: item.name_ranges,
1728                })
1729                .collect(),
1730        ))
1731    }
1732
1733    fn buffer_snapshot_for_excerpt<'a>(
1734        &'a self,
1735        excerpt_id: &'a ExcerptId,
1736    ) -> Option<(usize, &'a BufferSnapshot)> {
1737        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1738        cursor.seek(&Some(excerpt_id), Bias::Left, &());
1739        if let Some(excerpt) = cursor.item() {
1740            if excerpt.id == *excerpt_id {
1741                return Some((excerpt.buffer_id, &excerpt.buffer));
1742            }
1743        }
1744        None
1745    }
1746
1747    pub fn remote_selections_in_range<'a>(
1748        &'a self,
1749        range: &'a Range<Anchor>,
1750    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
1751        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1752        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
1753        cursor
1754            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
1755            .flat_map(move |excerpt| {
1756                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
1757                if excerpt.id == range.start.excerpt_id {
1758                    query_range.start = range.start.text_anchor.clone();
1759                }
1760                if excerpt.id == range.end.excerpt_id {
1761                    query_range.end = range.end.text_anchor.clone();
1762                }
1763
1764                excerpt
1765                    .buffer
1766                    .remote_selections_in_range(query_range)
1767                    .flat_map(move |(replica_id, selections)| {
1768                        selections.map(move |selection| {
1769                            let mut start = Anchor {
1770                                buffer_id: excerpt.buffer_id,
1771                                excerpt_id: excerpt.id.clone(),
1772                                text_anchor: selection.start.clone(),
1773                            };
1774                            let mut end = Anchor {
1775                                buffer_id: excerpt.buffer_id,
1776                                excerpt_id: excerpt.id.clone(),
1777                                text_anchor: selection.end.clone(),
1778                            };
1779                            if range.start.cmp(&start, self).unwrap().is_gt() {
1780                                start = range.start.clone();
1781                            }
1782                            if range.end.cmp(&end, self).unwrap().is_lt() {
1783                                end = range.end.clone();
1784                            }
1785
1786                            (
1787                                replica_id,
1788                                Selection {
1789                                    id: selection.id,
1790                                    start,
1791                                    end,
1792                                    reversed: selection.reversed,
1793                                    goal: selection.goal,
1794                                },
1795                            )
1796                        })
1797                    })
1798            })
1799    }
1800}
1801
1802impl History {
1803    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
1804        self.transaction_depth += 1;
1805        if self.transaction_depth == 1 {
1806            let id = post_inc(&mut self.next_transaction_id);
1807            self.undo_stack.push(Transaction {
1808                id,
1809                buffer_transactions: Default::default(),
1810                first_edit_at: now,
1811                last_edit_at: now,
1812            });
1813            Some(id)
1814        } else {
1815            None
1816        }
1817    }
1818
1819    fn end_transaction(
1820        &mut self,
1821        now: Instant,
1822        buffer_transactions: HashSet<(usize, TransactionId)>,
1823    ) -> bool {
1824        assert_ne!(self.transaction_depth, 0);
1825        self.transaction_depth -= 1;
1826        if self.transaction_depth == 0 {
1827            if buffer_transactions.is_empty() {
1828                self.undo_stack.pop();
1829                false
1830            } else {
1831                let transaction = self.undo_stack.last_mut().unwrap();
1832                transaction.last_edit_at = now;
1833                transaction.buffer_transactions.extend(buffer_transactions);
1834                true
1835            }
1836        } else {
1837            false
1838        }
1839    }
1840
1841    fn pop_undo(&mut self) -> Option<&Transaction> {
1842        assert_eq!(self.transaction_depth, 0);
1843        if let Some(transaction) = self.undo_stack.pop() {
1844            self.redo_stack.push(transaction);
1845            self.redo_stack.last()
1846        } else {
1847            None
1848        }
1849    }
1850
1851    fn pop_redo(&mut self) -> Option<&Transaction> {
1852        assert_eq!(self.transaction_depth, 0);
1853        if let Some(transaction) = self.redo_stack.pop() {
1854            self.undo_stack.push(transaction);
1855            self.undo_stack.last()
1856        } else {
1857            None
1858        }
1859    }
1860
1861    fn group(&mut self) -> Option<TransactionId> {
1862        let mut new_len = self.undo_stack.len();
1863        let mut transactions = self.undo_stack.iter_mut();
1864
1865        if let Some(mut transaction) = transactions.next_back() {
1866            while let Some(prev_transaction) = transactions.next_back() {
1867                if transaction.first_edit_at - prev_transaction.last_edit_at <= self.group_interval
1868                {
1869                    transaction = prev_transaction;
1870                    new_len -= 1;
1871                } else {
1872                    break;
1873                }
1874            }
1875        }
1876
1877        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
1878        if let Some(last_transaction) = transactions_to_keep.last_mut() {
1879            if let Some(transaction) = transactions_to_merge.last() {
1880                last_transaction.last_edit_at = transaction.last_edit_at;
1881            }
1882        }
1883
1884        self.undo_stack.truncate(new_len);
1885        self.undo_stack.last().map(|t| t.id)
1886    }
1887}
1888
1889impl Excerpt {
1890    fn new(
1891        id: ExcerptId,
1892        buffer_id: usize,
1893        buffer: BufferSnapshot,
1894        range: Range<text::Anchor>,
1895        has_trailing_newline: bool,
1896    ) -> Self {
1897        Excerpt {
1898            id,
1899            max_buffer_row: range.end.to_point(&buffer).row,
1900            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
1901            buffer_id,
1902            buffer,
1903            range,
1904            has_trailing_newline,
1905        }
1906    }
1907
1908    fn chunks_in_range<'a>(
1909        &'a self,
1910        range: Range<usize>,
1911        theme: Option<&'a SyntaxTheme>,
1912    ) -> ExcerptChunks<'a> {
1913        let content_start = self.range.start.to_offset(&self.buffer);
1914        let chunks_start = content_start + range.start;
1915        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1916
1917        let footer_height = if self.has_trailing_newline
1918            && range.start <= self.text_summary.bytes
1919            && range.end > self.text_summary.bytes
1920        {
1921            1
1922        } else {
1923            0
1924        };
1925
1926        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, theme);
1927
1928        ExcerptChunks {
1929            content_chunks,
1930            footer_height,
1931        }
1932    }
1933
1934    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
1935        let content_start = self.range.start.to_offset(&self.buffer);
1936        let bytes_start = content_start + range.start;
1937        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1938        let footer_height = if self.has_trailing_newline
1939            && range.start <= self.text_summary.bytes
1940            && range.end > self.text_summary.bytes
1941        {
1942            1
1943        } else {
1944            0
1945        };
1946        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
1947
1948        ExcerptBytes {
1949            content_bytes,
1950            footer_height,
1951        }
1952    }
1953
1954    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
1955        if text_anchor
1956            .cmp(&self.range.start, &self.buffer)
1957            .unwrap()
1958            .is_lt()
1959        {
1960            self.range.start.clone()
1961        } else if text_anchor
1962            .cmp(&self.range.end, &self.buffer)
1963            .unwrap()
1964            .is_gt()
1965        {
1966            self.range.end.clone()
1967        } else {
1968            text_anchor
1969        }
1970    }
1971
1972    fn contains(&self, anchor: &Anchor) -> bool {
1973        self.buffer_id == anchor.buffer_id
1974            && self
1975                .range
1976                .start
1977                .cmp(&anchor.text_anchor, &self.buffer)
1978                .unwrap()
1979                .is_le()
1980            && self
1981                .range
1982                .end
1983                .cmp(&anchor.text_anchor, &self.buffer)
1984                .unwrap()
1985                .is_ge()
1986    }
1987}
1988
1989impl fmt::Debug for Excerpt {
1990    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1991        f.debug_struct("Excerpt")
1992            .field("id", &self.id)
1993            .field("buffer_id", &self.buffer_id)
1994            .field("range", &self.range)
1995            .field("text_summary", &self.text_summary)
1996            .field("has_trailing_newline", &self.has_trailing_newline)
1997            .finish()
1998    }
1999}
2000
2001impl sum_tree::Item for Excerpt {
2002    type Summary = ExcerptSummary;
2003
2004    fn summary(&self) -> Self::Summary {
2005        let mut text = self.text_summary.clone();
2006        if self.has_trailing_newline {
2007            text += TextSummary::from("\n");
2008        }
2009        ExcerptSummary {
2010            excerpt_id: self.id.clone(),
2011            max_buffer_row: self.max_buffer_row,
2012            text,
2013        }
2014    }
2015}
2016
2017impl sum_tree::Summary for ExcerptSummary {
2018    type Context = ();
2019
2020    fn add_summary(&mut self, summary: &Self, _: &()) {
2021        debug_assert!(summary.excerpt_id > self.excerpt_id);
2022        self.excerpt_id = summary.excerpt_id.clone();
2023        self.text.add_summary(&summary.text, &());
2024        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2025    }
2026}
2027
2028impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2029    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2030        *self += &summary.text;
2031    }
2032}
2033
2034impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2035    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2036        *self += summary.text.bytes;
2037    }
2038}
2039
2040impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2041    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2042        Ord::cmp(self, &cursor_location.text.bytes)
2043    }
2044}
2045
2046impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2047    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2048        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2049    }
2050}
2051
2052impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2053    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2054        *self += summary.text.lines;
2055    }
2056}
2057
2058impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2059    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2060        *self += summary.text.lines_utf16
2061    }
2062}
2063
2064impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2065    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2066        *self = Some(&summary.excerpt_id);
2067    }
2068}
2069
2070impl<'a> MultiBufferRows<'a> {
2071    pub fn seek(&mut self, row: u32) {
2072        self.buffer_row_range = 0..0;
2073
2074        self.excerpts
2075            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2076        if self.excerpts.item().is_none() {
2077            self.excerpts.prev(&());
2078
2079            if self.excerpts.item().is_none() && row == 0 {
2080                self.buffer_row_range = 0..1;
2081                return;
2082            }
2083        }
2084
2085        if let Some(excerpt) = self.excerpts.item() {
2086            let overshoot = row - self.excerpts.start().row;
2087            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2088            self.buffer_row_range.start = excerpt_start + overshoot;
2089            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2090        }
2091    }
2092}
2093
2094impl<'a> Iterator for MultiBufferRows<'a> {
2095    type Item = Option<u32>;
2096
2097    fn next(&mut self) -> Option<Self::Item> {
2098        loop {
2099            if !self.buffer_row_range.is_empty() {
2100                let row = Some(self.buffer_row_range.start);
2101                self.buffer_row_range.start += 1;
2102                return Some(row);
2103            }
2104            self.excerpts.item()?;
2105            self.excerpts.next(&());
2106            let excerpt = self.excerpts.item()?;
2107            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2108            self.buffer_row_range.end =
2109                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2110        }
2111    }
2112}
2113
2114impl<'a> MultiBufferChunks<'a> {
2115    pub fn offset(&self) -> usize {
2116        self.range.start
2117    }
2118
2119    pub fn seek(&mut self, offset: usize) {
2120        self.range.start = offset;
2121        self.excerpts.seek(&offset, Bias::Right, &());
2122        if let Some(excerpt) = self.excerpts.item() {
2123            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2124                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2125                self.theme,
2126            ));
2127        } else {
2128            self.excerpt_chunks = None;
2129        }
2130    }
2131}
2132
2133impl<'a> Iterator for MultiBufferChunks<'a> {
2134    type Item = Chunk<'a>;
2135
2136    fn next(&mut self) -> Option<Self::Item> {
2137        if self.range.is_empty() {
2138            None
2139        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2140            self.range.start += chunk.text.len();
2141            Some(chunk)
2142        } else {
2143            self.excerpts.next(&());
2144            let excerpt = self.excerpts.item()?;
2145            self.excerpt_chunks = Some(
2146                excerpt.chunks_in_range(0..self.range.end - self.excerpts.start(), self.theme),
2147            );
2148            self.next()
2149        }
2150    }
2151}
2152
2153impl<'a> MultiBufferBytes<'a> {
2154    fn consume(&mut self, len: usize) {
2155        self.range.start += len;
2156        self.chunk = &self.chunk[len..];
2157
2158        if !self.range.is_empty() && self.chunk.is_empty() {
2159            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2160                self.chunk = chunk;
2161            } else {
2162                self.excerpts.next(&());
2163                if let Some(excerpt) = self.excerpts.item() {
2164                    let mut excerpt_bytes =
2165                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2166                    self.chunk = excerpt_bytes.next().unwrap();
2167                    self.excerpt_bytes = Some(excerpt_bytes);
2168                }
2169            }
2170        }
2171    }
2172}
2173
2174impl<'a> Iterator for MultiBufferBytes<'a> {
2175    type Item = &'a [u8];
2176
2177    fn next(&mut self) -> Option<Self::Item> {
2178        let chunk = self.chunk;
2179        if chunk.is_empty() {
2180            None
2181        } else {
2182            self.consume(chunk.len());
2183            Some(chunk)
2184        }
2185    }
2186}
2187
2188impl<'a> io::Read for MultiBufferBytes<'a> {
2189    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2190        let len = cmp::min(buf.len(), self.chunk.len());
2191        buf[..len].copy_from_slice(&self.chunk[..len]);
2192        if len > 0 {
2193            self.consume(len);
2194        }
2195        Ok(len)
2196    }
2197}
2198
2199impl<'a> Iterator for ExcerptBytes<'a> {
2200    type Item = &'a [u8];
2201
2202    fn next(&mut self) -> Option<Self::Item> {
2203        if let Some(chunk) = self.content_bytes.next() {
2204            if !chunk.is_empty() {
2205                return Some(chunk);
2206            }
2207        }
2208
2209        if self.footer_height > 0 {
2210            let result = &NEWLINES[..self.footer_height];
2211            self.footer_height = 0;
2212            return Some(result);
2213        }
2214
2215        None
2216    }
2217}
2218
2219impl<'a> Iterator for ExcerptChunks<'a> {
2220    type Item = Chunk<'a>;
2221
2222    fn next(&mut self) -> Option<Self::Item> {
2223        if let Some(chunk) = self.content_chunks.next() {
2224            return Some(chunk);
2225        }
2226
2227        if self.footer_height > 0 {
2228            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2229            self.footer_height = 0;
2230            return Some(Chunk {
2231                text,
2232                ..Default::default()
2233            });
2234        }
2235
2236        None
2237    }
2238}
2239
2240impl ToOffset for Point {
2241    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2242        snapshot.point_to_offset(*self)
2243    }
2244}
2245
2246impl ToOffset for PointUtf16 {
2247    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2248        snapshot.point_utf16_to_offset(*self)
2249    }
2250}
2251
2252impl ToOffset for usize {
2253    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2254        assert!(*self <= snapshot.len(), "offset is out of range");
2255        *self
2256    }
2257}
2258
2259impl ToPoint for usize {
2260    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2261        snapshot.offset_to_point(*self)
2262    }
2263}
2264
2265impl ToPoint for Point {
2266    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2267        *self
2268    }
2269}
2270
2271#[cfg(test)]
2272mod tests {
2273    use super::*;
2274    use gpui::MutableAppContext;
2275    use language::{Buffer, Rope};
2276    use rand::prelude::*;
2277    use std::env;
2278    use text::{Point, RandomCharIter};
2279    use util::test::sample_text;
2280
2281    #[gpui::test]
2282    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2283        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2284        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2285
2286        let snapshot = multibuffer.read(cx).snapshot(cx);
2287        assert_eq!(snapshot.text(), buffer.read(cx).text());
2288
2289        assert_eq!(
2290            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2291            (0..buffer.read(cx).row_count())
2292                .map(Some)
2293                .collect::<Vec<_>>()
2294        );
2295
2296        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2297        let snapshot = multibuffer.read(cx).snapshot(cx);
2298
2299        assert_eq!(snapshot.text(), buffer.read(cx).text());
2300        assert_eq!(
2301            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2302            (0..buffer.read(cx).row_count())
2303                .map(Some)
2304                .collect::<Vec<_>>()
2305        );
2306    }
2307
2308    #[gpui::test]
2309    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2310        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2311        let guest_buffer = cx.add_model(|cx| {
2312            let message = host_buffer.read(cx).to_proto();
2313            Buffer::from_proto(1, message, None, cx).unwrap()
2314        });
2315        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2316        let snapshot = multibuffer.read(cx).snapshot(cx);
2317        assert_eq!(snapshot.text(), "a");
2318
2319        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2320        let snapshot = multibuffer.read(cx).snapshot(cx);
2321        assert_eq!(snapshot.text(), "ab");
2322
2323        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2324        let snapshot = multibuffer.read(cx).snapshot(cx);
2325        assert_eq!(snapshot.text(), "abc");
2326    }
2327
2328    #[gpui::test]
2329    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2330        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2331        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2332        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2333
2334        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2335            let subscription = multibuffer.subscribe();
2336            multibuffer.push_excerpt(
2337                ExcerptProperties {
2338                    buffer: &buffer_1,
2339                    range: Point::new(1, 2)..Point::new(2, 5),
2340                },
2341                cx,
2342            );
2343            assert_eq!(
2344                subscription.consume().into_inner(),
2345                [Edit {
2346                    old: 0..0,
2347                    new: 0..10
2348                }]
2349            );
2350
2351            multibuffer.push_excerpt(
2352                ExcerptProperties {
2353                    buffer: &buffer_1,
2354                    range: Point::new(3, 3)..Point::new(4, 4),
2355                },
2356                cx,
2357            );
2358            multibuffer.push_excerpt(
2359                ExcerptProperties {
2360                    buffer: &buffer_2,
2361                    range: Point::new(3, 1)..Point::new(3, 3),
2362                },
2363                cx,
2364            );
2365            assert_eq!(
2366                subscription.consume().into_inner(),
2367                [Edit {
2368                    old: 10..10,
2369                    new: 10..22
2370                }]
2371            );
2372
2373            subscription
2374        });
2375
2376        let snapshot = multibuffer.read(cx).snapshot(cx);
2377        assert_eq!(
2378            snapshot.text(),
2379            concat!(
2380                "bbbb\n",  // Preserve newlines
2381                "ccccc\n", //
2382                "ddd\n",   //
2383                "eeee\n",  //
2384                "jj"       //
2385            )
2386        );
2387        assert_eq!(
2388            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2389            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2390        );
2391        assert_eq!(
2392            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2393            [Some(3), Some(4), Some(3)]
2394        );
2395        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2396        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2397        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(1, 5)));
2398        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(2, 0)));
2399        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(4, 0)));
2400        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(2, 0)..Point::new(3, 0)));
2401        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 0)..Point::new(4, 2)));
2402        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 2)..Point::new(4, 2)));
2403
2404        buffer_1.update(cx, |buffer, cx| {
2405            buffer.edit(
2406                [
2407                    Point::new(0, 0)..Point::new(0, 0),
2408                    Point::new(2, 1)..Point::new(2, 3),
2409                ],
2410                "\n",
2411                cx,
2412            );
2413        });
2414
2415        let snapshot = multibuffer.read(cx).snapshot(cx);
2416        assert_eq!(
2417            snapshot.text(),
2418            concat!(
2419                "bbbb\n", // Preserve newlines
2420                "c\n",    //
2421                "cc\n",   //
2422                "ddd\n",  //
2423                "eeee\n", //
2424                "jj"      //
2425            )
2426        );
2427
2428        assert_eq!(
2429            subscription.consume().into_inner(),
2430            [Edit {
2431                old: 6..8,
2432                new: 6..7
2433            }]
2434        );
2435
2436        let snapshot = multibuffer.read(cx).snapshot(cx);
2437        assert_eq!(
2438            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2439            Point::new(0, 4)
2440        );
2441        assert_eq!(
2442            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2443            Point::new(0, 4)
2444        );
2445        assert_eq!(
2446            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2447            Point::new(5, 1)
2448        );
2449        assert_eq!(
2450            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2451            Point::new(5, 2)
2452        );
2453        assert_eq!(
2454            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2455            Point::new(5, 2)
2456        );
2457
2458        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2459            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2460            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2461            multibuffer.snapshot(cx)
2462        });
2463
2464        assert_eq!(
2465            snapshot.text(),
2466            concat!(
2467                "bbbb\n", // Preserve newlines
2468                "c\n",    //
2469                "cc\n",   //
2470                "ddd\n",  //
2471                "eeee",   //
2472            )
2473        );
2474    }
2475
2476    #[gpui::test]
2477    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
2478        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2479
2480        let snapshot = multibuffer.read(cx).snapshot(cx);
2481        assert_eq!(snapshot.text(), "");
2482        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
2483        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
2484    }
2485
2486    #[gpui::test]
2487    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
2488        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2489        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2490        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2491        buffer.update(cx, |buffer, cx| {
2492            buffer.edit([0..0], "X", cx);
2493            buffer.edit([5..5], "Y", cx);
2494        });
2495        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2496
2497        assert_eq!(old_snapshot.text(), "abcd");
2498        assert_eq!(new_snapshot.text(), "XabcdY");
2499
2500        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2501        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2502        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
2503        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
2504    }
2505
2506    #[gpui::test]
2507    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
2508        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2509        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
2510        let multibuffer = cx.add_model(|cx| {
2511            let mut multibuffer = MultiBuffer::new(0);
2512            multibuffer.push_excerpt(
2513                ExcerptProperties {
2514                    buffer: &buffer_1,
2515                    range: 0..4,
2516                },
2517                cx,
2518            );
2519            multibuffer.push_excerpt(
2520                ExcerptProperties {
2521                    buffer: &buffer_2,
2522                    range: 0..5,
2523                },
2524                cx,
2525            );
2526            multibuffer
2527        });
2528        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2529
2530        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
2531        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
2532        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2533        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2534        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2535        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2536
2537        buffer_1.update(cx, |buffer, cx| {
2538            buffer.edit([0..0], "W", cx);
2539            buffer.edit([5..5], "X", cx);
2540        });
2541        buffer_2.update(cx, |buffer, cx| {
2542            buffer.edit([0..0], "Y", cx);
2543            buffer.edit([6..0], "Z", cx);
2544        });
2545        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2546
2547        assert_eq!(old_snapshot.text(), "abcd\nefghi");
2548        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
2549
2550        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2551        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2552        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
2553        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
2554        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
2555        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
2556        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
2557        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
2558        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
2559        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
2560    }
2561
2562    #[gpui::test]
2563    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
2564        cx: &mut MutableAppContext,
2565    ) {
2566        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2567        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
2568        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2569
2570        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
2571        // Add an excerpt from buffer 1 that spans this new insertion.
2572        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
2573        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
2574            multibuffer.push_excerpt(
2575                ExcerptProperties {
2576                    buffer: &buffer_1,
2577                    range: 0..7,
2578                },
2579                cx,
2580            )
2581        });
2582
2583        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
2584        assert_eq!(snapshot_1.text(), "abcd123");
2585
2586        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
2587        let (excerpt_id_2, excerpt_id_3, _) = multibuffer.update(cx, |multibuffer, cx| {
2588            multibuffer.remove_excerpts([&excerpt_id_1], cx);
2589            (
2590                multibuffer.push_excerpt(
2591                    ExcerptProperties {
2592                        buffer: &buffer_2,
2593                        range: 0..4,
2594                    },
2595                    cx,
2596                ),
2597                multibuffer.push_excerpt(
2598                    ExcerptProperties {
2599                        buffer: &buffer_2,
2600                        range: 6..10,
2601                    },
2602                    cx,
2603                ),
2604                multibuffer.push_excerpt(
2605                    ExcerptProperties {
2606                        buffer: &buffer_2,
2607                        range: 12..16,
2608                    },
2609                    cx,
2610                ),
2611            )
2612        });
2613        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
2614        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
2615
2616        // The old excerpt id has been reused.
2617        assert_eq!(excerpt_id_2, excerpt_id_1);
2618
2619        // Resolve some anchors from the previous snapshot in the new snapshot.
2620        // Although there is still an excerpt with the same id, it is for
2621        // a different buffer, so we don't attempt to resolve the old text
2622        // anchor in the new buffer.
2623        assert_eq!(
2624            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
2625            0
2626        );
2627        assert_eq!(
2628            snapshot_2.summaries_for_anchors::<usize, _>(&[
2629                snapshot_1.anchor_before(2),
2630                snapshot_1.anchor_after(3)
2631            ]),
2632            vec![0, 0]
2633        );
2634        let refresh =
2635            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
2636        assert_eq!(
2637            refresh,
2638            &[
2639                (0, snapshot_2.anchor_before(0), false),
2640                (1, snapshot_2.anchor_after(0), false),
2641            ]
2642        );
2643
2644        // Replace the middle excerpt with a smaller excerpt in buffer 2,
2645        // that intersects the old excerpt.
2646        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
2647            multibuffer.remove_excerpts([&excerpt_id_3], cx);
2648            multibuffer.insert_excerpt_after(
2649                &excerpt_id_3,
2650                ExcerptProperties {
2651                    buffer: &buffer_2,
2652                    range: 5..8,
2653                },
2654                cx,
2655            )
2656        });
2657
2658        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
2659        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
2660        assert_ne!(excerpt_id_5, excerpt_id_3);
2661
2662        // Resolve some anchors from the previous snapshot in the new snapshot.
2663        // The anchor in the middle excerpt snaps to the beginning of the
2664        // excerpt, since it is not
2665        let anchors = [
2666            snapshot_2.anchor_before(0),
2667            snapshot_2.anchor_after(2),
2668            snapshot_2.anchor_after(6),
2669            snapshot_2.anchor_after(14),
2670        ];
2671        assert_eq!(
2672            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
2673            &[0, 2, 9, 13]
2674        );
2675
2676        let new_anchors = snapshot_3.refresh_anchors(&anchors);
2677        assert_eq!(
2678            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
2679            &[(0, true), (1, true), (2, true), (3, true)]
2680        );
2681        assert_eq!(
2682            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
2683            &[0, 2, 7, 13]
2684        );
2685    }
2686
2687    #[gpui::test(iterations = 100)]
2688    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
2689        let operations = env::var("OPERATIONS")
2690            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2691            .unwrap_or(10);
2692
2693        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
2694        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2695        let mut excerpt_ids = Vec::new();
2696        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
2697        let mut anchors = Vec::new();
2698        let mut old_versions = Vec::new();
2699
2700        for _ in 0..operations {
2701            match rng.gen_range(0..100) {
2702                0..=19 if !buffers.is_empty() => {
2703                    let buffer = buffers.choose(&mut rng).unwrap();
2704                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
2705                }
2706                20..=29 if !expected_excerpts.is_empty() => {
2707                    let mut ids_to_remove = vec![];
2708                    for _ in 0..rng.gen_range(1..=3) {
2709                        if expected_excerpts.is_empty() {
2710                            break;
2711                        }
2712
2713                        let ix = rng.gen_range(0..expected_excerpts.len());
2714                        ids_to_remove.push(excerpt_ids.remove(ix));
2715                        let (buffer, range) = expected_excerpts.remove(ix);
2716                        let buffer = buffer.read(cx);
2717                        log::info!(
2718                            "Removing excerpt {}: {:?}",
2719                            ix,
2720                            buffer
2721                                .text_for_range(range.to_offset(&buffer))
2722                                .collect::<String>(),
2723                        );
2724                    }
2725                    ids_to_remove.sort_unstable();
2726                    multibuffer.update(cx, |multibuffer, cx| {
2727                        multibuffer.remove_excerpts(&ids_to_remove, cx)
2728                    });
2729                }
2730                30..=39 if !expected_excerpts.is_empty() => {
2731                    let multibuffer = multibuffer.read(cx).read(cx);
2732                    let offset =
2733                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
2734                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
2735                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
2736                    anchors.push(multibuffer.anchor_at(offset, bias));
2737                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
2738                }
2739                40..=44 if !anchors.is_empty() => {
2740                    let multibuffer = multibuffer.read(cx).read(cx);
2741                    anchors = multibuffer
2742                        .refresh_anchors(&anchors)
2743                        .into_iter()
2744                        .map(|a| a.1)
2745                        .collect();
2746                }
2747                _ => {
2748                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
2749                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
2750                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
2751                        buffers.last().unwrap()
2752                    } else {
2753                        buffers.choose(&mut rng).unwrap()
2754                    };
2755
2756                    let buffer = buffer_handle.read(cx);
2757                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2758                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2759                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
2760                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
2761                    let prev_excerpt_id = excerpt_ids
2762                        .get(prev_excerpt_ix)
2763                        .cloned()
2764                        .unwrap_or(ExcerptId::max());
2765                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
2766
2767                    log::info!(
2768                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
2769                        excerpt_ix,
2770                        expected_excerpts.len(),
2771                        buffer_handle.id(),
2772                        buffer.text(),
2773                        start_ix..end_ix,
2774                        &buffer.text()[start_ix..end_ix]
2775                    );
2776
2777                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
2778                        multibuffer.insert_excerpt_after(
2779                            &prev_excerpt_id,
2780                            ExcerptProperties {
2781                                buffer: &buffer_handle,
2782                                range: start_ix..end_ix,
2783                            },
2784                            cx,
2785                        )
2786                    });
2787
2788                    excerpt_ids.insert(excerpt_ix, excerpt_id);
2789                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
2790                }
2791            }
2792
2793            if rng.gen_bool(0.3) {
2794                multibuffer.update(cx, |multibuffer, cx| {
2795                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
2796                })
2797            }
2798
2799            let snapshot = multibuffer.read(cx).snapshot(cx);
2800
2801            let mut excerpt_starts = Vec::new();
2802            let mut expected_text = String::new();
2803            let mut expected_buffer_rows = Vec::new();
2804            for (buffer, range) in &expected_excerpts {
2805                let buffer = buffer.read(cx);
2806                let buffer_range = range.to_offset(buffer);
2807
2808                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
2809                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
2810                expected_text.push('\n');
2811
2812                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
2813                    ..=buffer.offset_to_point(buffer_range.end).row;
2814                for row in buffer_row_range {
2815                    expected_buffer_rows.push(Some(row));
2816                }
2817            }
2818            // Remove final trailing newline.
2819            if !expected_excerpts.is_empty() {
2820                expected_text.pop();
2821            }
2822
2823            // Always report one buffer row
2824            if expected_buffer_rows.is_empty() {
2825                expected_buffer_rows.push(Some(0));
2826            }
2827
2828            assert_eq!(snapshot.text(), expected_text);
2829            log::info!("MultiBuffer text: {:?}", expected_text);
2830
2831            assert_eq!(
2832                snapshot.buffer_rows(0).collect::<Vec<_>>(),
2833                expected_buffer_rows,
2834            );
2835
2836            for _ in 0..5 {
2837                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
2838                assert_eq!(
2839                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
2840                    &expected_buffer_rows[start_row..],
2841                    "buffer_rows({})",
2842                    start_row
2843                );
2844            }
2845
2846            assert_eq!(
2847                snapshot.max_buffer_row(),
2848                expected_buffer_rows
2849                    .into_iter()
2850                    .filter_map(|r| r)
2851                    .max()
2852                    .unwrap()
2853            );
2854
2855            let mut excerpt_starts = excerpt_starts.into_iter();
2856            for (buffer, range) in &expected_excerpts {
2857                let buffer_id = buffer.id();
2858                let buffer = buffer.read(cx);
2859                let buffer_range = range.to_offset(buffer);
2860                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
2861                let buffer_start_point_utf16 =
2862                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
2863
2864                let excerpt_start = excerpt_starts.next().unwrap();
2865                let mut offset = excerpt_start.bytes;
2866                let mut buffer_offset = buffer_range.start;
2867                let mut point = excerpt_start.lines;
2868                let mut buffer_point = buffer_start_point;
2869                let mut point_utf16 = excerpt_start.lines_utf16;
2870                let mut buffer_point_utf16 = buffer_start_point_utf16;
2871                for ch in buffer
2872                    .snapshot()
2873                    .chunks(buffer_range.clone(), None)
2874                    .flat_map(|c| c.text.chars())
2875                {
2876                    for _ in 0..ch.len_utf8() {
2877                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
2878                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
2879                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
2880                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
2881                        assert_eq!(
2882                            left_offset,
2883                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
2884                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
2885                            offset,
2886                            buffer_id,
2887                            buffer_offset,
2888                        );
2889                        assert_eq!(
2890                            right_offset,
2891                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
2892                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
2893                            offset,
2894                            buffer_id,
2895                            buffer_offset,
2896                        );
2897
2898                        let left_point = snapshot.clip_point(point, Bias::Left);
2899                        let right_point = snapshot.clip_point(point, Bias::Right);
2900                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
2901                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
2902                        assert_eq!(
2903                            left_point,
2904                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
2905                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
2906                            point,
2907                            buffer_id,
2908                            buffer_point,
2909                        );
2910                        assert_eq!(
2911                            right_point,
2912                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
2913                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
2914                            point,
2915                            buffer_id,
2916                            buffer_point,
2917                        );
2918
2919                        assert_eq!(
2920                            snapshot.point_to_offset(left_point),
2921                            left_offset,
2922                            "point_to_offset({:?})",
2923                            left_point,
2924                        );
2925                        assert_eq!(
2926                            snapshot.offset_to_point(left_offset),
2927                            left_point,
2928                            "offset_to_point({:?})",
2929                            left_offset,
2930                        );
2931
2932                        offset += 1;
2933                        buffer_offset += 1;
2934                        if ch == '\n' {
2935                            point += Point::new(1, 0);
2936                            buffer_point += Point::new(1, 0);
2937                        } else {
2938                            point += Point::new(0, 1);
2939                            buffer_point += Point::new(0, 1);
2940                        }
2941                    }
2942
2943                    for _ in 0..ch.len_utf16() {
2944                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
2945                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
2946                        let buffer_left_point_utf16 =
2947                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
2948                        let buffer_right_point_utf16 =
2949                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
2950                        assert_eq!(
2951                            left_point_utf16,
2952                            excerpt_start.lines_utf16
2953                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
2954                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
2955                            point_utf16,
2956                            buffer_id,
2957                            buffer_point_utf16,
2958                        );
2959                        assert_eq!(
2960                            right_point_utf16,
2961                            excerpt_start.lines_utf16
2962                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
2963                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
2964                            point_utf16,
2965                            buffer_id,
2966                            buffer_point_utf16,
2967                        );
2968
2969                        if ch == '\n' {
2970                            point_utf16 += PointUtf16::new(1, 0);
2971                            buffer_point_utf16 += PointUtf16::new(1, 0);
2972                        } else {
2973                            point_utf16 += PointUtf16::new(0, 1);
2974                            buffer_point_utf16 += PointUtf16::new(0, 1);
2975                        }
2976                    }
2977                }
2978            }
2979
2980            for (row, line) in expected_text.split('\n').enumerate() {
2981                assert_eq!(
2982                    snapshot.line_len(row as u32),
2983                    line.len() as u32,
2984                    "line_len({}).",
2985                    row
2986                );
2987            }
2988
2989            let text_rope = Rope::from(expected_text.as_str());
2990            for _ in 0..10 {
2991                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
2992                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2993
2994                let text_for_range = snapshot
2995                    .text_for_range(start_ix..end_ix)
2996                    .collect::<String>();
2997                assert_eq!(
2998                    text_for_range,
2999                    &expected_text[start_ix..end_ix],
3000                    "incorrect text for range {:?}",
3001                    start_ix..end_ix
3002                );
3003
3004                let excerpted_buffer_ranges =
3005                    multibuffer.read(cx).excerpted_buffers(start_ix..end_ix, cx);
3006                let excerpted_buffers_text = excerpted_buffer_ranges
3007                    .into_iter()
3008                    .map(|(buffer, buffer_range)| {
3009                        buffer
3010                            .read(cx)
3011                            .text_for_range(buffer_range)
3012                            .collect::<String>()
3013                    })
3014                    .collect::<Vec<_>>()
3015                    .join("\n");
3016                assert_eq!(excerpted_buffers_text, text_for_range);
3017
3018                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3019                assert_eq!(
3020                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3021                    expected_summary,
3022                    "incorrect summary for range {:?}",
3023                    start_ix..end_ix
3024                );
3025            }
3026
3027            // Anchor resolution
3028            for (anchor, resolved_offset) in anchors
3029                .iter()
3030                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3031            {
3032                assert_eq!(
3033                    snapshot.summary_for_anchor::<usize>(anchor),
3034                    resolved_offset
3035                );
3036            }
3037
3038            for _ in 0..10 {
3039                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3040                assert_eq!(
3041                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3042                    expected_text[..end_ix].chars().rev().collect::<String>(),
3043                );
3044            }
3045
3046            for _ in 0..10 {
3047                let end_ix = rng.gen_range(0..=text_rope.len());
3048                let start_ix = rng.gen_range(0..=end_ix);
3049                assert_eq!(
3050                    snapshot
3051                        .bytes_in_range(start_ix..end_ix)
3052                        .flatten()
3053                        .copied()
3054                        .collect::<Vec<_>>(),
3055                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3056                    "bytes_in_range({:?})",
3057                    start_ix..end_ix,
3058                );
3059            }
3060        }
3061
3062        let snapshot = multibuffer.read(cx).snapshot(cx);
3063        for (old_snapshot, subscription) in old_versions {
3064            let edits = subscription.consume().into_inner();
3065
3066            log::info!(
3067                "applying subscription edits to old text: {:?}: {:?}",
3068                old_snapshot.text(),
3069                edits,
3070            );
3071
3072            let mut text = old_snapshot.text();
3073            for edit in edits {
3074                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3075                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3076            }
3077            assert_eq!(text.to_string(), snapshot.text());
3078        }
3079    }
3080
3081    #[gpui::test]
3082    fn test_history(cx: &mut MutableAppContext) {
3083        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3084        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3085        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3086        let group_interval = multibuffer.read(cx).history.group_interval;
3087        multibuffer.update(cx, |multibuffer, cx| {
3088            multibuffer.push_excerpt(
3089                ExcerptProperties {
3090                    buffer: &buffer_1,
3091                    range: 0..buffer_1.read(cx).len(),
3092                },
3093                cx,
3094            );
3095            multibuffer.push_excerpt(
3096                ExcerptProperties {
3097                    buffer: &buffer_2,
3098                    range: 0..buffer_2.read(cx).len(),
3099                },
3100                cx,
3101            );
3102        });
3103
3104        let mut now = Instant::now();
3105
3106        multibuffer.update(cx, |multibuffer, cx| {
3107            multibuffer.start_transaction_at(now, cx);
3108            multibuffer.edit(
3109                [
3110                    Point::new(0, 0)..Point::new(0, 0),
3111                    Point::new(1, 0)..Point::new(1, 0),
3112                ],
3113                "A",
3114                cx,
3115            );
3116            multibuffer.edit(
3117                [
3118                    Point::new(0, 1)..Point::new(0, 1),
3119                    Point::new(1, 1)..Point::new(1, 1),
3120                ],
3121                "B",
3122                cx,
3123            );
3124            multibuffer.end_transaction_at(now, cx);
3125            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3126
3127            now += 2 * group_interval;
3128            multibuffer.start_transaction_at(now, cx);
3129            multibuffer.edit([2..2], "C", cx);
3130            multibuffer.end_transaction_at(now, cx);
3131            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3132
3133            multibuffer.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            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3146            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3147
3148            multibuffer.undo(cx);
3149            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3150
3151            multibuffer.redo(cx);
3152            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3153
3154            multibuffer.redo(cx);
3155            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3156
3157            multibuffer.undo(cx);
3158            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3159
3160            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3161            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3162
3163            multibuffer.undo(cx);
3164            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3165        });
3166    }
3167}