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