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        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 693
 694        while let Some(mut excerpt_id) = excerpt_ids.next() {
 695            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 696            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 697            if let Some(mut excerpt) = cursor.item() {
 698                if excerpt.id != *excerpt_id {
 699                    continue;
 700                }
 701                let mut old_start = cursor.start().1;
 702
 703                // Skip over the removed excerpt.
 704                loop {
 705                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 706                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 707                    }
 708                    cursor.next(&());
 709
 710                    // Skip over any subsequent excerpts that are also removed.
 711                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 712                        if let Some(next_excerpt) = cursor.item() {
 713                            if next_excerpt.id == *next_excerpt_id {
 714                                excerpt = next_excerpt;
 715                                excerpt_id = excerpt_ids.next().unwrap();
 716                                continue;
 717                            }
 718                        }
 719                    }
 720
 721                    break;
 722                }
 723
 724                // When removing the last excerpt, remove the trailing newline from
 725                // the previous excerpt.
 726                if cursor.item().is_none() && old_start > 0 {
 727                    old_start -= 1;
 728                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 729                }
 730
 731                // Push an edit for the removal of this run of excerpts.
 732                let old_end = cursor.start().1;
 733                let new_start = new_excerpts.summary().text.bytes;
 734                edits.push(Edit {
 735                    old: old_start..old_end,
 736                    new: new_start..new_start,
 737                });
 738            }
 739        }
 740        new_excerpts.push_tree(cursor.suffix(&()), &());
 741        drop(cursor);
 742        snapshot.excerpts = new_excerpts;
 743        self.subscriptions.publish_mut(edits);
 744        cx.notify();
 745    }
 746
 747    fn on_buffer_event(
 748        &mut self,
 749        _: ModelHandle<Buffer>,
 750        event: &Event,
 751        cx: &mut ModelContext<Self>,
 752    ) {
 753        cx.emit(event.clone());
 754    }
 755
 756    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Result<Task<Result<()>>> {
 757        let mut save_tasks = Vec::new();
 758        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 759            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx))?);
 760        }
 761
 762        Ok(cx.spawn(|_, _| async move {
 763            for save in save_tasks {
 764                save.await?;
 765            }
 766            Ok(())
 767        }))
 768    }
 769
 770    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 771        self.buffers
 772            .borrow()
 773            .values()
 774            .next()
 775            .and_then(|state| state.buffer.read(cx).language())
 776    }
 777
 778    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 779        self.as_singleton()?.read(cx).file()
 780    }
 781
 782    #[cfg(test)]
 783    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 784        self.as_singleton().unwrap().read(cx).is_parsing()
 785    }
 786
 787    fn sync(&self, cx: &AppContext) {
 788        let mut snapshot = self.snapshot.borrow_mut();
 789        let mut excerpts_to_edit = Vec::new();
 790        let mut reparsed = false;
 791        let mut diagnostics_updated = false;
 792        let mut is_dirty = false;
 793        let mut has_conflict = false;
 794        let mut buffers = self.buffers.borrow_mut();
 795        for buffer_state in buffers.values_mut() {
 796            let buffer = buffer_state.buffer.read(cx);
 797            let version = buffer.version();
 798            let parse_count = buffer.parse_count();
 799            let diagnostics_update_count = buffer.diagnostics_update_count();
 800
 801            let buffer_edited = version.gt(&buffer_state.last_version);
 802            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
 803            let buffer_diagnostics_updated =
 804                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
 805            if buffer_edited || buffer_reparsed || buffer_diagnostics_updated {
 806                buffer_state.last_version = version;
 807                buffer_state.last_parse_count = parse_count;
 808                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
 809                excerpts_to_edit.extend(
 810                    buffer_state
 811                        .excerpts
 812                        .iter()
 813                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
 814                );
 815            }
 816
 817            reparsed |= buffer_reparsed;
 818            diagnostics_updated |= buffer_diagnostics_updated;
 819            is_dirty |= buffer.is_dirty();
 820            has_conflict |= buffer.has_conflict();
 821        }
 822        if reparsed {
 823            snapshot.parse_count += 1;
 824        }
 825        if diagnostics_updated {
 826            snapshot.diagnostics_update_count += 1;
 827        }
 828        snapshot.is_dirty = is_dirty;
 829        snapshot.has_conflict = has_conflict;
 830
 831        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
 832
 833        let mut edits = Vec::new();
 834        let mut new_excerpts = SumTree::new();
 835        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 836
 837        for (id, buffer, buffer_edited) in excerpts_to_edit {
 838            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
 839            let old_excerpt = cursor.item().unwrap();
 840            let buffer_id = buffer.id();
 841            let buffer = buffer.read(cx);
 842
 843            let mut new_excerpt;
 844            if buffer_edited {
 845                edits.extend(
 846                    buffer
 847                        .edits_since_in_range::<usize>(
 848                            old_excerpt.buffer.version(),
 849                            old_excerpt.range.clone(),
 850                        )
 851                        .map(|mut edit| {
 852                            let excerpt_old_start = cursor.start().1;
 853                            let excerpt_new_start = new_excerpts.summary().text.bytes;
 854                            edit.old.start += excerpt_old_start;
 855                            edit.old.end += excerpt_old_start;
 856                            edit.new.start += excerpt_new_start;
 857                            edit.new.end += excerpt_new_start;
 858                            edit
 859                        }),
 860                );
 861
 862                new_excerpt = Excerpt::new(
 863                    id.clone(),
 864                    buffer_id,
 865                    buffer.snapshot(),
 866                    old_excerpt.range.clone(),
 867                    old_excerpt.has_trailing_newline,
 868                );
 869            } else {
 870                new_excerpt = old_excerpt.clone();
 871                new_excerpt.buffer = buffer.snapshot();
 872            }
 873
 874            new_excerpts.push(new_excerpt, &());
 875            cursor.next(&());
 876        }
 877        new_excerpts.push_tree(cursor.suffix(&()), &());
 878
 879        drop(cursor);
 880        snapshot.excerpts = new_excerpts;
 881
 882        self.subscriptions.publish(edits);
 883    }
 884}
 885
 886#[cfg(any(test, feature = "test-support"))]
 887impl MultiBuffer {
 888    pub fn randomly_edit(
 889        &mut self,
 890        rng: &mut impl rand::Rng,
 891        count: usize,
 892        cx: &mut ModelContext<Self>,
 893    ) {
 894        use text::RandomCharIter;
 895
 896        let snapshot = self.read(cx);
 897        let mut old_ranges: Vec<Range<usize>> = Vec::new();
 898        for _ in 0..count {
 899            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
 900            if last_end > snapshot.len() {
 901                break;
 902            }
 903            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
 904            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
 905            old_ranges.push(start_ix..end_ix);
 906        }
 907        let new_text_len = rng.gen_range(0..10);
 908        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
 909        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
 910        drop(snapshot);
 911
 912        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
 913    }
 914}
 915
 916impl Entity for MultiBuffer {
 917    type Event = language::Event;
 918}
 919
 920impl MultiBufferSnapshot {
 921    pub fn text(&self) -> String {
 922        self.chunks(0..self.len(), None)
 923            .map(|chunk| chunk.text)
 924            .collect()
 925    }
 926
 927    pub fn reversed_chars_at<'a, T: ToOffset>(
 928        &'a self,
 929        position: T,
 930    ) -> impl Iterator<Item = char> + 'a {
 931        let mut offset = position.to_offset(self);
 932        let mut cursor = self.excerpts.cursor::<usize>();
 933        cursor.seek(&offset, Bias::Left, &());
 934        let mut excerpt_chunks = cursor.item().map(|excerpt| {
 935            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
 936            let start = excerpt.range.start.to_offset(&excerpt.buffer);
 937            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
 938            excerpt.buffer.reversed_chunks_in_range(start..end)
 939        });
 940        iter::from_fn(move || {
 941            if offset == *cursor.start() {
 942                cursor.prev(&());
 943                let excerpt = cursor.item()?;
 944                excerpt_chunks = Some(
 945                    excerpt
 946                        .buffer
 947                        .reversed_chunks_in_range(excerpt.range.clone()),
 948                );
 949            }
 950
 951            let excerpt = cursor.item().unwrap();
 952            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
 953                offset -= 1;
 954                Some("\n")
 955            } else {
 956                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
 957                offset -= chunk.len();
 958                Some(chunk)
 959            }
 960        })
 961        .flat_map(|c| c.chars().rev())
 962    }
 963
 964    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
 965        let offset = position.to_offset(self);
 966        self.text_for_range(offset..self.len())
 967            .flat_map(|chunk| chunk.chars())
 968    }
 969
 970    pub fn text_for_range<'a, T: ToOffset>(
 971        &'a self,
 972        range: Range<T>,
 973    ) -> impl Iterator<Item = &'a str> {
 974        self.chunks(range, None).map(|chunk| chunk.text)
 975    }
 976
 977    pub fn is_line_blank(&self, row: u32) -> bool {
 978        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
 979            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
 980    }
 981
 982    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
 983    where
 984        T: ToOffset,
 985    {
 986        let position = position.to_offset(self);
 987        position == self.clip_offset(position, Bias::Left)
 988            && self
 989                .bytes_in_range(position..self.len())
 990                .flatten()
 991                .copied()
 992                .take(needle.len())
 993                .eq(needle.bytes())
 994    }
 995
 996    fn as_singleton(&self) -> Option<&BufferSnapshot> {
 997        let mut excerpts = self.excerpts.iter();
 998        let buffer = excerpts.next().map(|excerpt| &excerpt.buffer);
 999        if excerpts.next().is_none() {
1000            buffer
1001        } else {
1002            None
1003        }
1004    }
1005
1006    pub fn len(&self) -> usize {
1007        self.excerpts.summary().text.bytes
1008    }
1009
1010    pub fn max_buffer_row(&self) -> u32 {
1011        self.excerpts.summary().max_buffer_row
1012    }
1013
1014    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1015        let mut cursor = self.excerpts.cursor::<usize>();
1016        cursor.seek(&offset, Bias::Right, &());
1017        let overshoot = if let Some(excerpt) = cursor.item() {
1018            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1019            let buffer_offset = excerpt
1020                .buffer
1021                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1022            buffer_offset.saturating_sub(excerpt_start)
1023        } else {
1024            0
1025        };
1026        cursor.start() + overshoot
1027    }
1028
1029    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1030        let mut cursor = self.excerpts.cursor::<Point>();
1031        cursor.seek(&point, Bias::Right, &());
1032        let overshoot = if let Some(excerpt) = cursor.item() {
1033            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1034            let buffer_point = excerpt
1035                .buffer
1036                .clip_point(excerpt_start + (point - cursor.start()), bias);
1037            buffer_point.saturating_sub(excerpt_start)
1038        } else {
1039            Point::zero()
1040        };
1041        *cursor.start() + overshoot
1042    }
1043
1044    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1045        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1046        cursor.seek(&point, Bias::Right, &());
1047        let overshoot = if let Some(excerpt) = cursor.item() {
1048            let excerpt_start = excerpt
1049                .buffer
1050                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1051            let buffer_point = excerpt
1052                .buffer
1053                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1054            buffer_point.saturating_sub(excerpt_start)
1055        } else {
1056            PointUtf16::zero()
1057        };
1058        *cursor.start() + overshoot
1059    }
1060
1061    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1062        let range = range.start.to_offset(self)..range.end.to_offset(self);
1063        let mut excerpts = self.excerpts.cursor::<usize>();
1064        excerpts.seek(&range.start, Bias::Right, &());
1065
1066        let mut chunk = &[][..];
1067        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1068            let mut excerpt_bytes = excerpt
1069                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1070            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1071            Some(excerpt_bytes)
1072        } else {
1073            None
1074        };
1075
1076        MultiBufferBytes {
1077            range,
1078            excerpts,
1079            excerpt_bytes,
1080            chunk,
1081        }
1082    }
1083
1084    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1085        let mut result = MultiBufferRows {
1086            buffer_row_range: 0..0,
1087            excerpts: self.excerpts.cursor(),
1088        };
1089        result.seek(start_row);
1090        result
1091    }
1092
1093    pub fn chunks<'a, T: ToOffset>(
1094        &'a self,
1095        range: Range<T>,
1096        theme: Option<&'a SyntaxTheme>,
1097    ) -> MultiBufferChunks<'a> {
1098        let range = range.start.to_offset(self)..range.end.to_offset(self);
1099        let mut chunks = MultiBufferChunks {
1100            range: range.clone(),
1101            excerpts: self.excerpts.cursor(),
1102            excerpt_chunks: None,
1103            theme,
1104        };
1105        chunks.seek(range.start);
1106        chunks
1107    }
1108
1109    pub fn offset_to_point(&self, offset: usize) -> Point {
1110        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1111        cursor.seek(&offset, Bias::Right, &());
1112        if let Some(excerpt) = cursor.item() {
1113            let (start_offset, start_point) = cursor.start();
1114            let overshoot = offset - start_offset;
1115            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1116            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1117            let buffer_point = excerpt
1118                .buffer
1119                .offset_to_point(excerpt_start_offset + overshoot);
1120            *start_point + (buffer_point - excerpt_start_point)
1121        } else {
1122            self.excerpts.summary().text.lines
1123        }
1124    }
1125
1126    pub fn point_to_offset(&self, point: Point) -> usize {
1127        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1128        cursor.seek(&point, Bias::Right, &());
1129        if let Some(excerpt) = cursor.item() {
1130            let (start_point, start_offset) = cursor.start();
1131            let overshoot = point - start_point;
1132            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1133            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1134            let buffer_offset = excerpt
1135                .buffer
1136                .point_to_offset(excerpt_start_point + overshoot);
1137            *start_offset + buffer_offset - excerpt_start_offset
1138        } else {
1139            self.excerpts.summary().text.bytes
1140        }
1141    }
1142
1143    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1144        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1145        cursor.seek(&point, Bias::Right, &());
1146        if let Some(excerpt) = cursor.item() {
1147            let (start_point, start_offset) = cursor.start();
1148            let overshoot = point - start_point;
1149            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1150            let excerpt_start_point = excerpt
1151                .buffer
1152                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1153            let buffer_offset = excerpt
1154                .buffer
1155                .point_utf16_to_offset(excerpt_start_point + overshoot);
1156            *start_offset + (buffer_offset - excerpt_start_offset)
1157        } else {
1158            self.excerpts.summary().text.bytes
1159        }
1160    }
1161
1162    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1163        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1164            buffer
1165                .indent_column_for_line(range.start.row)
1166                .min(range.end.column)
1167                .saturating_sub(range.start.column)
1168        } else {
1169            0
1170        }
1171    }
1172
1173    pub fn line_len(&self, row: u32) -> u32 {
1174        if let Some((_, range)) = self.buffer_line_for_row(row) {
1175            range.end.column - range.start.column
1176        } else {
1177            0
1178        }
1179    }
1180
1181    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1182        let mut cursor = self.excerpts.cursor::<Point>();
1183        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1184        if let Some(excerpt) = cursor.item() {
1185            let overshoot = row - cursor.start().row;
1186            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1187            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1188            let buffer_row = excerpt_start.row + overshoot;
1189            let line_start = Point::new(buffer_row, 0);
1190            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1191            return Some((
1192                &excerpt.buffer,
1193                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1194            ));
1195        }
1196        None
1197    }
1198
1199    pub fn max_point(&self) -> Point {
1200        self.text_summary().lines
1201    }
1202
1203    pub fn text_summary(&self) -> TextSummary {
1204        self.excerpts.summary().text
1205    }
1206
1207    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1208    where
1209        D: TextDimension,
1210        O: ToOffset,
1211    {
1212        let mut summary = D::default();
1213        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1214        let mut cursor = self.excerpts.cursor::<usize>();
1215        cursor.seek(&range.start, Bias::Right, &());
1216        if let Some(excerpt) = cursor.item() {
1217            let mut end_before_newline = cursor.end(&());
1218            if excerpt.has_trailing_newline {
1219                end_before_newline -= 1;
1220            }
1221
1222            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1223            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1224            let end_in_excerpt =
1225                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1226            summary.add_assign(
1227                &excerpt
1228                    .buffer
1229                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1230            );
1231
1232            if range.end > end_before_newline {
1233                summary.add_assign(&D::from_text_summary(&TextSummary {
1234                    bytes: 1,
1235                    lines: Point::new(1 as u32, 0),
1236                    lines_utf16: PointUtf16::new(1 as u32, 0),
1237                    first_line_chars: 0,
1238                    last_line_chars: 0,
1239                    longest_row: 0,
1240                    longest_row_chars: 0,
1241                }));
1242            }
1243
1244            cursor.next(&());
1245        }
1246
1247        if range.end > *cursor.start() {
1248            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1249                &range.end,
1250                Bias::Right,
1251                &(),
1252            )));
1253            if let Some(excerpt) = cursor.item() {
1254                range.end = cmp::max(*cursor.start(), range.end);
1255
1256                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1257                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1258                summary.add_assign(
1259                    &excerpt
1260                        .buffer
1261                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1262                );
1263            }
1264        }
1265
1266        summary
1267    }
1268
1269    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1270    where
1271        D: TextDimension + Ord + Sub<D, Output = D>,
1272    {
1273        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1274        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1275        if cursor.item().is_none() {
1276            cursor.next(&());
1277        }
1278
1279        let mut position = D::from_text_summary(&cursor.start().text);
1280        if let Some(excerpt) = cursor.item() {
1281            if excerpt.id == anchor.excerpt_id {
1282                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1283                let buffer_position = anchor.text_anchor.summary::<D>(&excerpt.buffer);
1284                if buffer_position > excerpt_buffer_start {
1285                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1286                }
1287            }
1288        }
1289        position
1290    }
1291
1292    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1293    where
1294        D: TextDimension + Ord + Sub<D, Output = D>,
1295        I: 'a + IntoIterator<Item = &'a Anchor>,
1296    {
1297        let mut anchors = anchors.into_iter().peekable();
1298        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1299        let mut summaries = Vec::new();
1300        while let Some(anchor) = anchors.peek() {
1301            let excerpt_id = &anchor.excerpt_id;
1302            let excerpt_anchors = iter::from_fn(|| {
1303                let anchor = anchors.peek()?;
1304                if anchor.excerpt_id == *excerpt_id {
1305                    Some(&anchors.next().unwrap().text_anchor)
1306                } else {
1307                    None
1308                }
1309            });
1310
1311            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1312            if cursor.item().is_none() {
1313                cursor.next(&());
1314            }
1315
1316            let position = D::from_text_summary(&cursor.start().text);
1317            if let Some(excerpt) = cursor.item() {
1318                if excerpt.id == *excerpt_id {
1319                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1320                    summaries.extend(
1321                        excerpt
1322                            .buffer
1323                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1324                            .map(move |summary| {
1325                                let mut position = position.clone();
1326                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1327                                if summary > excerpt_buffer_start {
1328                                    position.add_assign(&(summary - excerpt_buffer_start));
1329                                }
1330                                position
1331                            }),
1332                    );
1333                    continue;
1334                }
1335            }
1336
1337            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1338        }
1339
1340        summaries
1341    }
1342
1343    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1344        self.anchor_at(position, Bias::Left)
1345    }
1346
1347    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1348        self.anchor_at(position, Bias::Right)
1349    }
1350
1351    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1352        let offset = position.to_offset(self);
1353        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1354        cursor.seek(&offset, Bias::Right, &());
1355        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1356            cursor.prev(&());
1357        }
1358        if let Some(excerpt) = cursor.item() {
1359            let mut overshoot = offset.saturating_sub(cursor.start().0);
1360            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1361                overshoot -= 1;
1362                bias = Bias::Right;
1363            }
1364
1365            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1366            let text_anchor =
1367                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1368            Anchor {
1369                excerpt_id: excerpt.id.clone(),
1370                text_anchor,
1371            }
1372        } else if offset == 0 && bias == Bias::Left {
1373            Anchor::min()
1374        } else {
1375            Anchor::max()
1376        }
1377    }
1378
1379    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1380        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1381        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1382        if let Some(excerpt) = cursor.item() {
1383            if excerpt.id == excerpt_id {
1384                let text_anchor = excerpt.clip_anchor(text_anchor);
1385                drop(cursor);
1386                return Anchor {
1387                    excerpt_id,
1388                    text_anchor,
1389                };
1390            }
1391        }
1392        panic!("excerpt not found");
1393    }
1394
1395    pub fn parse_count(&self) -> usize {
1396        self.parse_count
1397    }
1398
1399    pub fn enclosing_bracket_ranges<T: ToOffset>(
1400        &self,
1401        range: Range<T>,
1402    ) -> Option<(Range<usize>, Range<usize>)> {
1403        let range = range.start.to_offset(self)..range.end.to_offset(self);
1404
1405        let mut cursor = self.excerpts.cursor::<usize>();
1406        cursor.seek(&range.start, Bias::Right, &());
1407        let start_excerpt = cursor.item();
1408
1409        cursor.seek(&range.end, Bias::Right, &());
1410        let end_excerpt = cursor.item();
1411
1412        start_excerpt
1413            .zip(end_excerpt)
1414            .and_then(|(start_excerpt, end_excerpt)| {
1415                if start_excerpt.id != end_excerpt.id {
1416                    return None;
1417                }
1418
1419                let excerpt_buffer_start =
1420                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1421                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1422
1423                let start_in_buffer =
1424                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1425                let end_in_buffer =
1426                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1427                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
1428                    .buffer
1429                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
1430
1431                if start_bracket_range.start >= excerpt_buffer_start
1432                    && end_bracket_range.end < excerpt_buffer_end
1433                {
1434                    start_bracket_range.start =
1435                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
1436                    start_bracket_range.end =
1437                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
1438                    end_bracket_range.start =
1439                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
1440                    end_bracket_range.end =
1441                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
1442                    Some((start_bracket_range, end_bracket_range))
1443                } else {
1444                    None
1445                }
1446            })
1447    }
1448
1449    pub fn diagnostics_update_count(&self) -> usize {
1450        self.diagnostics_update_count
1451    }
1452
1453    pub fn language(&self) -> Option<&Arc<Language>> {
1454        self.excerpts
1455            .iter()
1456            .next()
1457            .and_then(|excerpt| excerpt.buffer.language())
1458    }
1459
1460    pub fn is_dirty(&self) -> bool {
1461        self.is_dirty
1462    }
1463
1464    pub fn has_conflict(&self) -> bool {
1465        self.has_conflict
1466    }
1467
1468    pub fn diagnostic_group<'a, O>(
1469        &'a self,
1470        group_id: usize,
1471    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1472    where
1473        O: text::FromAnchor + 'a,
1474    {
1475        self.as_singleton()
1476            .into_iter()
1477            .flat_map(move |buffer| buffer.diagnostic_group(group_id))
1478    }
1479
1480    pub fn diagnostics_in_range<'a, T, O>(
1481        &'a self,
1482        range: Range<T>,
1483    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1484    where
1485        T: 'a + ToOffset,
1486        O: 'a + text::FromAnchor,
1487    {
1488        self.as_singleton().into_iter().flat_map(move |buffer| {
1489            buffer.diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
1490        })
1491    }
1492
1493    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
1494        let range = range.start.to_offset(self)..range.end.to_offset(self);
1495
1496        let mut cursor = self.excerpts.cursor::<usize>();
1497        cursor.seek(&range.start, Bias::Right, &());
1498        let start_excerpt = cursor.item();
1499
1500        cursor.seek(&range.end, Bias::Right, &());
1501        let end_excerpt = cursor.item();
1502
1503        start_excerpt
1504            .zip(end_excerpt)
1505            .and_then(|(start_excerpt, end_excerpt)| {
1506                if start_excerpt.id != end_excerpt.id {
1507                    return None;
1508                }
1509
1510                let excerpt_buffer_start =
1511                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1512                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1513
1514                let start_in_buffer =
1515                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1516                let end_in_buffer =
1517                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1518                let mut ancestor_buffer_range = start_excerpt
1519                    .buffer
1520                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
1521                ancestor_buffer_range.start =
1522                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
1523                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
1524
1525                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
1526                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
1527                Some(start..end)
1528            })
1529    }
1530
1531    fn buffer_snapshot_for_excerpt<'a>(
1532        &'a self,
1533        excerpt_id: &'a ExcerptId,
1534    ) -> Option<&'a BufferSnapshot> {
1535        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1536        cursor.seek(&Some(excerpt_id), Bias::Left, &());
1537        if let Some(excerpt) = cursor.item() {
1538            if excerpt.id == *excerpt_id {
1539                return Some(&excerpt.buffer);
1540            }
1541        }
1542        None
1543    }
1544
1545    pub fn remote_selections_in_range<'a>(
1546        &'a self,
1547        range: &'a Range<Anchor>,
1548    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
1549        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1550        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
1551        cursor
1552            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
1553            .flat_map(move |excerpt| {
1554                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
1555                if excerpt.id == range.start.excerpt_id {
1556                    query_range.start = range.start.text_anchor.clone();
1557                }
1558                if excerpt.id == range.end.excerpt_id {
1559                    query_range.end = range.end.text_anchor.clone();
1560                }
1561
1562                excerpt
1563                    .buffer
1564                    .remote_selections_in_range(query_range)
1565                    .flat_map(move |(replica_id, selections)| {
1566                        selections.map(move |selection| {
1567                            let mut start = Anchor {
1568                                excerpt_id: excerpt.id.clone(),
1569                                text_anchor: selection.start.clone(),
1570                            };
1571                            let mut end = Anchor {
1572                                excerpt_id: excerpt.id.clone(),
1573                                text_anchor: selection.end.clone(),
1574                            };
1575                            if range.start.cmp(&start, self).unwrap().is_gt() {
1576                                start = range.start.clone();
1577                            }
1578                            if range.end.cmp(&end, self).unwrap().is_lt() {
1579                                end = range.end.clone();
1580                            }
1581
1582                            (
1583                                replica_id,
1584                                Selection {
1585                                    id: selection.id,
1586                                    start,
1587                                    end,
1588                                    reversed: selection.reversed,
1589                                    goal: selection.goal,
1590                                },
1591                            )
1592                        })
1593                    })
1594            })
1595    }
1596}
1597
1598impl History {
1599    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
1600        self.transaction_depth += 1;
1601        if self.transaction_depth == 1 {
1602            let id = post_inc(&mut self.next_transaction_id);
1603            self.undo_stack.push(Transaction {
1604                id,
1605                buffer_transactions: Default::default(),
1606                first_edit_at: now,
1607                last_edit_at: now,
1608            });
1609            Some(id)
1610        } else {
1611            None
1612        }
1613    }
1614
1615    fn end_transaction(
1616        &mut self,
1617        now: Instant,
1618        buffer_transactions: HashSet<(usize, TransactionId)>,
1619    ) -> bool {
1620        assert_ne!(self.transaction_depth, 0);
1621        self.transaction_depth -= 1;
1622        if self.transaction_depth == 0 {
1623            if buffer_transactions.is_empty() {
1624                self.undo_stack.pop();
1625                false
1626            } else {
1627                let transaction = self.undo_stack.last_mut().unwrap();
1628                transaction.last_edit_at = now;
1629                transaction.buffer_transactions.extend(buffer_transactions);
1630                true
1631            }
1632        } else {
1633            false
1634        }
1635    }
1636
1637    fn pop_undo(&mut self) -> Option<&Transaction> {
1638        assert_eq!(self.transaction_depth, 0);
1639        if let Some(transaction) = self.undo_stack.pop() {
1640            self.redo_stack.push(transaction);
1641            self.redo_stack.last()
1642        } else {
1643            None
1644        }
1645    }
1646
1647    fn pop_redo(&mut self) -> Option<&Transaction> {
1648        assert_eq!(self.transaction_depth, 0);
1649        if let Some(transaction) = self.redo_stack.pop() {
1650            self.undo_stack.push(transaction);
1651            self.undo_stack.last()
1652        } else {
1653            None
1654        }
1655    }
1656
1657    fn group(&mut self) -> Option<TransactionId> {
1658        let mut new_len = self.undo_stack.len();
1659        let mut transactions = self.undo_stack.iter_mut();
1660
1661        if let Some(mut transaction) = transactions.next_back() {
1662            while let Some(prev_transaction) = transactions.next_back() {
1663                if transaction.first_edit_at - prev_transaction.last_edit_at <= self.group_interval
1664                {
1665                    transaction = prev_transaction;
1666                    new_len -= 1;
1667                } else {
1668                    break;
1669                }
1670            }
1671        }
1672
1673        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
1674        if let Some(last_transaction) = transactions_to_keep.last_mut() {
1675            if let Some(transaction) = transactions_to_merge.last() {
1676                last_transaction.last_edit_at = transaction.last_edit_at;
1677            }
1678        }
1679
1680        self.undo_stack.truncate(new_len);
1681        self.undo_stack.last().map(|t| t.id)
1682    }
1683}
1684
1685impl Excerpt {
1686    fn new(
1687        id: ExcerptId,
1688        buffer_id: usize,
1689        buffer: BufferSnapshot,
1690        range: Range<text::Anchor>,
1691        has_trailing_newline: bool,
1692    ) -> Self {
1693        Excerpt {
1694            id,
1695            max_buffer_row: range.end.to_point(&buffer).row,
1696            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
1697            buffer_id,
1698            buffer,
1699            range,
1700            has_trailing_newline,
1701        }
1702    }
1703
1704    fn chunks_in_range<'a>(
1705        &'a self,
1706        range: Range<usize>,
1707        theme: Option<&'a SyntaxTheme>,
1708    ) -> ExcerptChunks<'a> {
1709        let content_start = self.range.start.to_offset(&self.buffer);
1710        let chunks_start = content_start + range.start;
1711        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1712
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
1722        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, theme);
1723
1724        ExcerptChunks {
1725            content_chunks,
1726            footer_height,
1727        }
1728    }
1729
1730    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
1731        let content_start = self.range.start.to_offset(&self.buffer);
1732        let bytes_start = content_start + range.start;
1733        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
1734        let footer_height = if self.has_trailing_newline
1735            && range.start <= self.text_summary.bytes
1736            && range.end > self.text_summary.bytes
1737        {
1738            1
1739        } else {
1740            0
1741        };
1742        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
1743
1744        ExcerptBytes {
1745            content_bytes,
1746            footer_height,
1747        }
1748    }
1749
1750    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
1751        if text_anchor
1752            .cmp(&self.range.start, &self.buffer)
1753            .unwrap()
1754            .is_lt()
1755        {
1756            self.range.start.clone()
1757        } else if text_anchor
1758            .cmp(&self.range.end, &self.buffer)
1759            .unwrap()
1760            .is_gt()
1761        {
1762            self.range.end.clone()
1763        } else {
1764            text_anchor
1765        }
1766    }
1767}
1768
1769impl fmt::Debug for Excerpt {
1770    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1771        f.debug_struct("Excerpt")
1772            .field("id", &self.id)
1773            .field("buffer_id", &self.buffer_id)
1774            .field("range", &self.range)
1775            .field("text_summary", &self.text_summary)
1776            .field("has_trailing_newline", &self.has_trailing_newline)
1777            .finish()
1778    }
1779}
1780
1781impl sum_tree::Item for Excerpt {
1782    type Summary = ExcerptSummary;
1783
1784    fn summary(&self) -> Self::Summary {
1785        let mut text = self.text_summary.clone();
1786        if self.has_trailing_newline {
1787            text += TextSummary::from("\n");
1788        }
1789        ExcerptSummary {
1790            excerpt_id: self.id.clone(),
1791            max_buffer_row: self.max_buffer_row,
1792            text,
1793        }
1794    }
1795}
1796
1797impl sum_tree::Summary for ExcerptSummary {
1798    type Context = ();
1799
1800    fn add_summary(&mut self, summary: &Self, _: &()) {
1801        debug_assert!(summary.excerpt_id > self.excerpt_id);
1802        self.excerpt_id = summary.excerpt_id.clone();
1803        self.text.add_summary(&summary.text, &());
1804        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
1805    }
1806}
1807
1808impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
1809    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1810        *self += &summary.text;
1811    }
1812}
1813
1814impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
1815    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1816        *self += summary.text.bytes;
1817    }
1818}
1819
1820impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
1821    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
1822        Ord::cmp(self, &cursor_location.text.bytes)
1823    }
1824}
1825
1826impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
1827    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
1828        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
1829    }
1830}
1831
1832impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
1833    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1834        *self += summary.text.lines;
1835    }
1836}
1837
1838impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
1839    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1840        *self += summary.text.lines_utf16
1841    }
1842}
1843
1844impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
1845    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1846        *self = Some(&summary.excerpt_id);
1847    }
1848}
1849
1850impl<'a> MultiBufferRows<'a> {
1851    pub fn seek(&mut self, row: u32) {
1852        self.buffer_row_range = 0..0;
1853
1854        self.excerpts
1855            .seek_forward(&Point::new(row, 0), Bias::Right, &());
1856        if self.excerpts.item().is_none() {
1857            self.excerpts.prev(&());
1858
1859            if self.excerpts.item().is_none() && row == 0 {
1860                self.buffer_row_range = 0..1;
1861                return;
1862            }
1863        }
1864
1865        if let Some(excerpt) = self.excerpts.item() {
1866            let overshoot = row - self.excerpts.start().row;
1867            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
1868            self.buffer_row_range.start = excerpt_start + overshoot;
1869            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
1870        }
1871    }
1872}
1873
1874impl<'a> Iterator for MultiBufferRows<'a> {
1875    type Item = Option<u32>;
1876
1877    fn next(&mut self) -> Option<Self::Item> {
1878        loop {
1879            if !self.buffer_row_range.is_empty() {
1880                let row = Some(self.buffer_row_range.start);
1881                self.buffer_row_range.start += 1;
1882                return Some(row);
1883            }
1884            self.excerpts.item()?;
1885            self.excerpts.next(&());
1886            let excerpt = self.excerpts.item()?;
1887            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
1888            self.buffer_row_range.end =
1889                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
1890        }
1891    }
1892}
1893
1894impl<'a> MultiBufferChunks<'a> {
1895    pub fn offset(&self) -> usize {
1896        self.range.start
1897    }
1898
1899    pub fn seek(&mut self, offset: usize) {
1900        self.range.start = offset;
1901        self.excerpts.seek(&offset, Bias::Right, &());
1902        if let Some(excerpt) = self.excerpts.item() {
1903            self.excerpt_chunks = Some(excerpt.chunks_in_range(
1904                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
1905                self.theme,
1906            ));
1907        } else {
1908            self.excerpt_chunks = None;
1909        }
1910    }
1911}
1912
1913impl<'a> Iterator for MultiBufferChunks<'a> {
1914    type Item = Chunk<'a>;
1915
1916    fn next(&mut self) -> Option<Self::Item> {
1917        if self.range.is_empty() {
1918            None
1919        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
1920            self.range.start += chunk.text.len();
1921            Some(chunk)
1922        } else {
1923            self.excerpts.next(&());
1924            let excerpt = self.excerpts.item()?;
1925            self.excerpt_chunks = Some(
1926                excerpt.chunks_in_range(0..self.range.end - self.excerpts.start(), self.theme),
1927            );
1928            self.next()
1929        }
1930    }
1931}
1932
1933impl<'a> MultiBufferBytes<'a> {
1934    fn consume(&mut self, len: usize) {
1935        self.range.start += len;
1936        self.chunk = &self.chunk[len..];
1937
1938        if !self.range.is_empty() && self.chunk.is_empty() {
1939            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
1940                self.chunk = chunk;
1941            } else {
1942                self.excerpts.next(&());
1943                if let Some(excerpt) = self.excerpts.item() {
1944                    let mut excerpt_bytes =
1945                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
1946                    self.chunk = excerpt_bytes.next().unwrap();
1947                    self.excerpt_bytes = Some(excerpt_bytes);
1948                }
1949            }
1950        }
1951    }
1952}
1953
1954impl<'a> Iterator for MultiBufferBytes<'a> {
1955    type Item = &'a [u8];
1956
1957    fn next(&mut self) -> Option<Self::Item> {
1958        let chunk = self.chunk;
1959        if chunk.is_empty() {
1960            None
1961        } else {
1962            self.consume(chunk.len());
1963            Some(chunk)
1964        }
1965    }
1966}
1967
1968impl<'a> io::Read for MultiBufferBytes<'a> {
1969    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
1970        let len = cmp::min(buf.len(), self.chunk.len());
1971        buf[..len].copy_from_slice(&self.chunk[..len]);
1972        if len > 0 {
1973            self.consume(len);
1974        }
1975        Ok(len)
1976    }
1977}
1978
1979impl<'a> Iterator for ExcerptBytes<'a> {
1980    type Item = &'a [u8];
1981
1982    fn next(&mut self) -> Option<Self::Item> {
1983        if let Some(chunk) = self.content_bytes.next() {
1984            if !chunk.is_empty() {
1985                return Some(chunk);
1986            }
1987        }
1988
1989        if self.footer_height > 0 {
1990            let result = &NEWLINES[..self.footer_height];
1991            self.footer_height = 0;
1992            return Some(result);
1993        }
1994
1995        None
1996    }
1997}
1998
1999impl<'a> Iterator for ExcerptChunks<'a> {
2000    type Item = Chunk<'a>;
2001
2002    fn next(&mut self) -> Option<Self::Item> {
2003        if let Some(chunk) = self.content_chunks.next() {
2004            return Some(chunk);
2005        }
2006
2007        if self.footer_height > 0 {
2008            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2009            self.footer_height = 0;
2010            return Some(Chunk {
2011                text,
2012                ..Default::default()
2013            });
2014        }
2015
2016        None
2017    }
2018}
2019
2020impl ToOffset for Point {
2021    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2022        snapshot.point_to_offset(*self)
2023    }
2024}
2025
2026impl ToOffset for PointUtf16 {
2027    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2028        snapshot.point_utf16_to_offset(*self)
2029    }
2030}
2031
2032impl ToOffset for usize {
2033    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2034        assert!(*self <= snapshot.len(), "offset is out of range");
2035        *self
2036    }
2037}
2038
2039impl ToPoint for usize {
2040    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2041        snapshot.offset_to_point(*self)
2042    }
2043}
2044
2045impl ToPoint for Point {
2046    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2047        *self
2048    }
2049}
2050
2051#[cfg(test)]
2052mod tests {
2053    use super::*;
2054    use gpui::MutableAppContext;
2055    use language::{Buffer, Rope};
2056    use rand::prelude::*;
2057    use std::env;
2058    use text::{Point, RandomCharIter};
2059    use util::test::sample_text;
2060
2061    #[gpui::test]
2062    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2063        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2064        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2065
2066        let snapshot = multibuffer.read(cx).snapshot(cx);
2067        assert_eq!(snapshot.text(), buffer.read(cx).text());
2068
2069        assert_eq!(
2070            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2071            (0..buffer.read(cx).row_count())
2072                .map(Some)
2073                .collect::<Vec<_>>()
2074        );
2075
2076        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2077        let snapshot = multibuffer.read(cx).snapshot(cx);
2078
2079        assert_eq!(snapshot.text(), buffer.read(cx).text());
2080        assert_eq!(
2081            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2082            (0..buffer.read(cx).row_count())
2083                .map(Some)
2084                .collect::<Vec<_>>()
2085        );
2086    }
2087
2088    #[gpui::test]
2089    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2090        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2091        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2092        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2093
2094        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2095            let subscription = multibuffer.subscribe();
2096            multibuffer.push_excerpt(
2097                ExcerptProperties {
2098                    buffer: &buffer_1,
2099                    range: Point::new(1, 2)..Point::new(2, 5),
2100                },
2101                cx,
2102            );
2103            assert_eq!(
2104                subscription.consume().into_inner(),
2105                [Edit {
2106                    old: 0..0,
2107                    new: 0..10
2108                }]
2109            );
2110
2111            multibuffer.push_excerpt(
2112                ExcerptProperties {
2113                    buffer: &buffer_1,
2114                    range: Point::new(3, 3)..Point::new(4, 4),
2115                },
2116                cx,
2117            );
2118            multibuffer.push_excerpt(
2119                ExcerptProperties {
2120                    buffer: &buffer_2,
2121                    range: Point::new(3, 1)..Point::new(3, 3),
2122                },
2123                cx,
2124            );
2125            assert_eq!(
2126                subscription.consume().into_inner(),
2127                [Edit {
2128                    old: 10..10,
2129                    new: 10..22
2130                }]
2131            );
2132
2133            subscription
2134        });
2135
2136        let snapshot = multibuffer.read(cx).snapshot(cx);
2137        assert_eq!(
2138            snapshot.text(),
2139            concat!(
2140                "bbbb\n",  // Preserve newlines
2141                "ccccc\n", //
2142                "ddd\n",   //
2143                "eeee\n",  //
2144                "jj"       //
2145            )
2146        );
2147        assert_eq!(
2148            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2149            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2150        );
2151        assert_eq!(
2152            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2153            [Some(3), Some(4), Some(3)]
2154        );
2155        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2156        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2157
2158        buffer_1.update(cx, |buffer, cx| {
2159            buffer.edit(
2160                [
2161                    Point::new(0, 0)..Point::new(0, 0),
2162                    Point::new(2, 1)..Point::new(2, 3),
2163                ],
2164                "\n",
2165                cx,
2166            );
2167        });
2168
2169        let snapshot = multibuffer.read(cx).snapshot(cx);
2170        assert_eq!(
2171            snapshot.text(),
2172            concat!(
2173                "bbbb\n", // Preserve newlines
2174                "c\n",    //
2175                "cc\n",   //
2176                "ddd\n",  //
2177                "eeee\n", //
2178                "jj"      //
2179            )
2180        );
2181
2182        assert_eq!(
2183            subscription.consume().into_inner(),
2184            [Edit {
2185                old: 6..8,
2186                new: 6..7
2187            }]
2188        );
2189
2190        let snapshot = multibuffer.read(cx).snapshot(cx);
2191        assert_eq!(
2192            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2193            Point::new(0, 4)
2194        );
2195        assert_eq!(
2196            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2197            Point::new(0, 4)
2198        );
2199        assert_eq!(
2200            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2201            Point::new(5, 1)
2202        );
2203        assert_eq!(
2204            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2205            Point::new(5, 2)
2206        );
2207        assert_eq!(
2208            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2209            Point::new(5, 2)
2210        );
2211
2212        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2213            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2214            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2215            multibuffer.snapshot(cx)
2216        });
2217
2218        assert_eq!(
2219            snapshot.text(),
2220            concat!(
2221                "bbbb\n", // Preserve newlines
2222                "c\n",    //
2223                "cc\n",   //
2224                "ddd\n",  //
2225                "eeee",   //
2226            )
2227        );
2228    }
2229
2230    #[gpui::test]
2231    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
2232        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2233
2234        let snapshot = multibuffer.read(cx).snapshot(cx);
2235        assert_eq!(snapshot.text(), "");
2236        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
2237        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
2238    }
2239
2240    #[gpui::test]
2241    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
2242        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2243        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2244        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2245        buffer.update(cx, |buffer, cx| {
2246            buffer.edit([0..0], "X", cx);
2247            buffer.edit([5..5], "Y", cx);
2248        });
2249        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2250
2251        assert_eq!(old_snapshot.text(), "abcd");
2252        assert_eq!(new_snapshot.text(), "XabcdY");
2253
2254        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2255        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2256        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
2257        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
2258    }
2259
2260    #[gpui::test]
2261    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
2262        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2263        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
2264        let multibuffer = cx.add_model(|cx| {
2265            let mut multibuffer = MultiBuffer::new(0);
2266            multibuffer.push_excerpt(
2267                ExcerptProperties {
2268                    buffer: &buffer_1,
2269                    range: 0..4,
2270                },
2271                cx,
2272            );
2273            multibuffer.push_excerpt(
2274                ExcerptProperties {
2275                    buffer: &buffer_2,
2276                    range: 0..5,
2277                },
2278                cx,
2279            );
2280            multibuffer
2281        });
2282        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2283
2284        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
2285        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
2286        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2287        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2288        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2289        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2290
2291        buffer_1.update(cx, |buffer, cx| {
2292            buffer.edit([0..0], "W", cx);
2293            buffer.edit([5..5], "X", cx);
2294        });
2295        buffer_2.update(cx, |buffer, cx| {
2296            buffer.edit([0..0], "Y", cx);
2297            buffer.edit([6..0], "Z", cx);
2298        });
2299        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2300
2301        assert_eq!(old_snapshot.text(), "abcd\nefghi");
2302        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
2303
2304        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2305        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2306        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
2307        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
2308        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
2309        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
2310        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
2311        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
2312        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
2313        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
2314    }
2315
2316    #[gpui::test(iterations = 100)]
2317    fn test_random_excerpts(cx: &mut MutableAppContext, mut rng: StdRng) {
2318        let operations = env::var("OPERATIONS")
2319            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2320            .unwrap_or(10);
2321
2322        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
2323        let list = cx.add_model(|_| MultiBuffer::new(0));
2324        let mut excerpt_ids = Vec::new();
2325        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
2326        let mut old_versions = Vec::new();
2327
2328        for _ in 0..operations {
2329            match rng.gen_range(0..100) {
2330                0..=19 if !buffers.is_empty() => {
2331                    let buffer = buffers.choose(&mut rng).unwrap();
2332                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
2333                }
2334                20..=29 if !expected_excerpts.is_empty() => {
2335                    let mut ids_to_remove = vec![];
2336                    for _ in 0..rng.gen_range(1..=3) {
2337                        if expected_excerpts.is_empty() {
2338                            break;
2339                        }
2340
2341                        let ix = rng.gen_range(0..expected_excerpts.len());
2342                        ids_to_remove.push(excerpt_ids.remove(ix));
2343                        let (buffer, range) = expected_excerpts.remove(ix);
2344                        let buffer = buffer.read(cx);
2345                        log::info!(
2346                            "Removing excerpt {}: {:?}",
2347                            ix,
2348                            buffer
2349                                .text_for_range(range.to_offset(&buffer))
2350                                .collect::<String>(),
2351                        );
2352                    }
2353                    ids_to_remove.sort_unstable();
2354                    list.update(cx, |list, cx| list.remove_excerpts(&ids_to_remove, cx));
2355                }
2356                _ => {
2357                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
2358                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
2359                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
2360                        buffers.last().unwrap()
2361                    } else {
2362                        buffers.choose(&mut rng).unwrap()
2363                    };
2364
2365                    let buffer = buffer_handle.read(cx);
2366                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2367                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2368                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
2369                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
2370                    let prev_excerpt_id = excerpt_ids
2371                        .get(prev_excerpt_ix)
2372                        .cloned()
2373                        .unwrap_or(ExcerptId::max());
2374                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
2375
2376                    log::info!(
2377                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
2378                        excerpt_ix,
2379                        expected_excerpts.len(),
2380                        buffer_handle.id(),
2381                        buffer.text(),
2382                        start_ix..end_ix,
2383                        &buffer.text()[start_ix..end_ix]
2384                    );
2385
2386                    let excerpt_id = list.update(cx, |list, cx| {
2387                        list.insert_excerpt_after(
2388                            &prev_excerpt_id,
2389                            ExcerptProperties {
2390                                buffer: &buffer_handle,
2391                                range: start_ix..end_ix,
2392                            },
2393                            cx,
2394                        )
2395                    });
2396
2397                    excerpt_ids.insert(excerpt_ix, excerpt_id);
2398                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
2399                }
2400            }
2401
2402            if rng.gen_bool(0.3) {
2403                list.update(cx, |list, cx| {
2404                    old_versions.push((list.snapshot(cx), list.subscribe()));
2405                })
2406            }
2407
2408            let snapshot = list.read(cx).snapshot(cx);
2409
2410            let mut excerpt_starts = Vec::new();
2411            let mut expected_text = String::new();
2412            let mut expected_buffer_rows = Vec::new();
2413            for (buffer, range) in &expected_excerpts {
2414                let buffer = buffer.read(cx);
2415                let buffer_range = range.to_offset(buffer);
2416
2417                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
2418                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
2419                expected_text.push('\n');
2420
2421                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
2422                    ..=buffer.offset_to_point(buffer_range.end).row;
2423                for row in buffer_row_range {
2424                    expected_buffer_rows.push(Some(row));
2425                }
2426            }
2427            // Remove final trailing newline.
2428            if !expected_excerpts.is_empty() {
2429                expected_text.pop();
2430            }
2431
2432            // Always report one buffer row
2433            if expected_buffer_rows.is_empty() {
2434                expected_buffer_rows.push(Some(0));
2435            }
2436
2437            assert_eq!(snapshot.text(), expected_text);
2438            log::info!("MultiBuffer text: {:?}", expected_text);
2439
2440            assert_eq!(
2441                snapshot.buffer_rows(0).collect::<Vec<_>>(),
2442                expected_buffer_rows,
2443            );
2444
2445            for _ in 0..5 {
2446                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
2447                assert_eq!(
2448                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
2449                    &expected_buffer_rows[start_row..],
2450                    "buffer_rows({})",
2451                    start_row
2452                );
2453            }
2454
2455            assert_eq!(
2456                snapshot.max_buffer_row(),
2457                expected_buffer_rows
2458                    .into_iter()
2459                    .filter_map(|r| r)
2460                    .max()
2461                    .unwrap()
2462            );
2463
2464            let mut excerpt_starts = excerpt_starts.into_iter();
2465            for (buffer, range) in &expected_excerpts {
2466                let buffer_id = buffer.id();
2467                let buffer = buffer.read(cx);
2468                let buffer_range = range.to_offset(buffer);
2469                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
2470                let buffer_start_point_utf16 =
2471                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
2472
2473                let excerpt_start = excerpt_starts.next().unwrap();
2474                let mut offset = excerpt_start.bytes;
2475                let mut buffer_offset = buffer_range.start;
2476                let mut point = excerpt_start.lines;
2477                let mut buffer_point = buffer_start_point;
2478                let mut point_utf16 = excerpt_start.lines_utf16;
2479                let mut buffer_point_utf16 = buffer_start_point_utf16;
2480                for ch in buffer
2481                    .snapshot()
2482                    .chunks(buffer_range.clone(), None)
2483                    .flat_map(|c| c.text.chars())
2484                {
2485                    for _ in 0..ch.len_utf8() {
2486                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
2487                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
2488                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
2489                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
2490                        assert_eq!(
2491                            left_offset,
2492                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
2493                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
2494                            offset,
2495                            buffer_id,
2496                            buffer_offset,
2497                        );
2498                        assert_eq!(
2499                            right_offset,
2500                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
2501                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
2502                            offset,
2503                            buffer_id,
2504                            buffer_offset,
2505                        );
2506
2507                        let left_point = snapshot.clip_point(point, Bias::Left);
2508                        let right_point = snapshot.clip_point(point, Bias::Right);
2509                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
2510                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
2511                        assert_eq!(
2512                            left_point,
2513                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
2514                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
2515                            point,
2516                            buffer_id,
2517                            buffer_point,
2518                        );
2519                        assert_eq!(
2520                            right_point,
2521                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
2522                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
2523                            point,
2524                            buffer_id,
2525                            buffer_point,
2526                        );
2527
2528                        assert_eq!(
2529                            snapshot.point_to_offset(left_point),
2530                            left_offset,
2531                            "point_to_offset({:?})",
2532                            left_point,
2533                        );
2534                        assert_eq!(
2535                            snapshot.offset_to_point(left_offset),
2536                            left_point,
2537                            "offset_to_point({:?})",
2538                            left_offset,
2539                        );
2540
2541                        offset += 1;
2542                        buffer_offset += 1;
2543                        if ch == '\n' {
2544                            point += Point::new(1, 0);
2545                            buffer_point += Point::new(1, 0);
2546                        } else {
2547                            point += Point::new(0, 1);
2548                            buffer_point += Point::new(0, 1);
2549                        }
2550                    }
2551
2552                    for _ in 0..ch.len_utf16() {
2553                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
2554                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
2555                        let buffer_left_point_utf16 =
2556                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
2557                        let buffer_right_point_utf16 =
2558                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
2559                        assert_eq!(
2560                            left_point_utf16,
2561                            excerpt_start.lines_utf16
2562                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
2563                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
2564                            point_utf16,
2565                            buffer_id,
2566                            buffer_point_utf16,
2567                        );
2568                        assert_eq!(
2569                            right_point_utf16,
2570                            excerpt_start.lines_utf16
2571                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
2572                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
2573                            point_utf16,
2574                            buffer_id,
2575                            buffer_point_utf16,
2576                        );
2577
2578                        if ch == '\n' {
2579                            point_utf16 += PointUtf16::new(1, 0);
2580                            buffer_point_utf16 += PointUtf16::new(1, 0);
2581                        } else {
2582                            point_utf16 += PointUtf16::new(0, 1);
2583                            buffer_point_utf16 += PointUtf16::new(0, 1);
2584                        }
2585                    }
2586                }
2587            }
2588
2589            for (row, line) in expected_text.split('\n').enumerate() {
2590                assert_eq!(
2591                    snapshot.line_len(row as u32),
2592                    line.len() as u32,
2593                    "line_len({}).",
2594                    row
2595                );
2596            }
2597
2598            let text_rope = Rope::from(expected_text.as_str());
2599            for _ in 0..10 {
2600                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
2601                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2602
2603                assert_eq!(
2604                    snapshot
2605                        .text_for_range(start_ix..end_ix)
2606                        .collect::<String>(),
2607                    &expected_text[start_ix..end_ix],
2608                    "incorrect text for range {:?}",
2609                    start_ix..end_ix
2610                );
2611
2612                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
2613                assert_eq!(
2614                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
2615                    expected_summary,
2616                    "incorrect summary for range {:?}",
2617                    start_ix..end_ix
2618                );
2619            }
2620
2621            for _ in 0..10 {
2622                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
2623                assert_eq!(
2624                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
2625                    expected_text[..end_ix].chars().rev().collect::<String>(),
2626                );
2627            }
2628
2629            for _ in 0..10 {
2630                let end_ix = rng.gen_range(0..=text_rope.len());
2631                let start_ix = rng.gen_range(0..=end_ix);
2632                assert_eq!(
2633                    snapshot
2634                        .bytes_in_range(start_ix..end_ix)
2635                        .flatten()
2636                        .copied()
2637                        .collect::<Vec<_>>(),
2638                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
2639                    "bytes_in_range({:?})",
2640                    start_ix..end_ix,
2641                );
2642            }
2643        }
2644
2645        let snapshot = list.read(cx).snapshot(cx);
2646        for (old_snapshot, subscription) in old_versions {
2647            let edits = subscription.consume().into_inner();
2648
2649            log::info!(
2650                "applying subscription edits to old text: {:?}: {:?}",
2651                old_snapshot.text(),
2652                edits,
2653            );
2654
2655            let mut text = old_snapshot.text();
2656            for edit in edits {
2657                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
2658                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
2659            }
2660            assert_eq!(text.to_string(), snapshot.text());
2661        }
2662    }
2663
2664    #[gpui::test]
2665    fn test_history(cx: &mut MutableAppContext) {
2666        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
2667        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
2668        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2669        let group_interval = multibuffer.read(cx).history.group_interval;
2670        multibuffer.update(cx, |multibuffer, cx| {
2671            multibuffer.push_excerpt(
2672                ExcerptProperties {
2673                    buffer: &buffer_1,
2674                    range: 0..buffer_1.read(cx).len(),
2675                },
2676                cx,
2677            );
2678            multibuffer.push_excerpt(
2679                ExcerptProperties {
2680                    buffer: &buffer_2,
2681                    range: 0..buffer_2.read(cx).len(),
2682                },
2683                cx,
2684            );
2685        });
2686
2687        let mut now = Instant::now();
2688
2689        multibuffer.update(cx, |multibuffer, cx| {
2690            multibuffer.start_transaction_at(now, cx);
2691            multibuffer.edit(
2692                [
2693                    Point::new(0, 0)..Point::new(0, 0),
2694                    Point::new(1, 0)..Point::new(1, 0),
2695                ],
2696                "A",
2697                cx,
2698            );
2699            multibuffer.edit(
2700                [
2701                    Point::new(0, 1)..Point::new(0, 1),
2702                    Point::new(1, 1)..Point::new(1, 1),
2703                ],
2704                "B",
2705                cx,
2706            );
2707            multibuffer.end_transaction_at(now, cx);
2708            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2709
2710            now += 2 * group_interval;
2711            multibuffer.start_transaction_at(now, cx);
2712            multibuffer.edit([2..2], "C", cx);
2713            multibuffer.end_transaction_at(now, cx);
2714            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
2715
2716            multibuffer.undo(cx);
2717            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2718
2719            multibuffer.undo(cx);
2720            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
2721
2722            multibuffer.redo(cx);
2723            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2724
2725            multibuffer.redo(cx);
2726            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
2727
2728            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
2729            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2730
2731            multibuffer.undo(cx);
2732            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
2733
2734            multibuffer.redo(cx);
2735            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2736
2737            multibuffer.redo(cx);
2738            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
2739
2740            multibuffer.undo(cx);
2741            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
2742
2743            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
2744            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
2745
2746            multibuffer.undo(cx);
2747            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
2748        });
2749    }
2750}