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