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};
   8pub use language::Completion;
   9use language::{
  10    Buffer, BufferChunks, BufferSnapshot, Chunk, DiagnosticEntry, Event, File, Language, Outline,
  11    OutlineItem, Selection, ToOffset as _, ToPoint as _, TransactionId,
  12};
  13use std::{
  14    cell::{Ref, RefCell},
  15    cmp, fmt, io,
  16    iter::{self, FromIterator},
  17    ops::{Range, Sub},
  18    str,
  19    sync::Arc,
  20    time::{Duration, Instant},
  21};
  22use sum_tree::{Bias, Cursor, SumTree};
  23use text::{
  24    locator::Locator,
  25    rope::TextDimension,
  26    subscription::{Subscription, Topic},
  27    AnchorRangeExt as _, Edit, Point, PointUtf16, TextSummary,
  28};
  29use theme::SyntaxTheme;
  30use util::post_inc;
  31
  32const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  33
  34pub type ExcerptId = Locator;
  35
  36pub struct MultiBuffer {
  37    snapshot: RefCell<MultiBufferSnapshot>,
  38    buffers: RefCell<HashMap<usize, BufferState>>,
  39    subscriptions: Topic,
  40    singleton: bool,
  41    replica_id: ReplicaId,
  42    history: History,
  43}
  44
  45struct History {
  46    next_transaction_id: usize,
  47    undo_stack: Vec<Transaction>,
  48    redo_stack: Vec<Transaction>,
  49    transaction_depth: usize,
  50    group_interval: Duration,
  51}
  52
  53struct Transaction {
  54    id: usize,
  55    buffer_transactions: HashSet<(usize, text::TransactionId)>,
  56    first_edit_at: Instant,
  57    last_edit_at: Instant,
  58}
  59
  60pub trait ToOffset: 'static + fmt::Debug {
  61    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  62}
  63
  64pub trait ToPoint: 'static + fmt::Debug {
  65    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  66}
  67
  68struct BufferState {
  69    buffer: ModelHandle<Buffer>,
  70    last_version: clock::Global,
  71    last_parse_count: usize,
  72    last_selections_update_count: usize,
  73    last_diagnostics_update_count: usize,
  74    excerpts: Vec<ExcerptId>,
  75    _subscriptions: [gpui::Subscription; 2],
  76}
  77
  78#[derive(Clone, Default)]
  79pub struct MultiBufferSnapshot {
  80    singleton: bool,
  81    excerpts: SumTree<Excerpt>,
  82    parse_count: usize,
  83    diagnostics_update_count: usize,
  84    is_dirty: bool,
  85    has_conflict: bool,
  86}
  87
  88pub struct ExcerptProperties<'a, T> {
  89    pub buffer: &'a ModelHandle<Buffer>,
  90    pub range: Range<T>,
  91}
  92
  93#[derive(Clone)]
  94struct Excerpt {
  95    id: ExcerptId,
  96    buffer_id: usize,
  97    buffer: BufferSnapshot,
  98    range: Range<text::Anchor>,
  99    max_buffer_row: u32,
 100    text_summary: TextSummary,
 101    has_trailing_newline: bool,
 102}
 103
 104#[derive(Clone, Debug, Default)]
 105struct ExcerptSummary {
 106    excerpt_id: ExcerptId,
 107    max_buffer_row: u32,
 108    text: TextSummary,
 109}
 110
 111pub struct MultiBufferRows<'a> {
 112    buffer_row_range: Range<u32>,
 113    excerpts: Cursor<'a, Excerpt, Point>,
 114}
 115
 116pub struct MultiBufferChunks<'a> {
 117    range: Range<usize>,
 118    excerpts: Cursor<'a, Excerpt, usize>,
 119    excerpt_chunks: Option<ExcerptChunks<'a>>,
 120    theme: Option<&'a SyntaxTheme>,
 121}
 122
 123pub struct MultiBufferBytes<'a> {
 124    range: Range<usize>,
 125    excerpts: Cursor<'a, Excerpt, usize>,
 126    excerpt_bytes: Option<ExcerptBytes<'a>>,
 127    chunk: &'a [u8],
 128}
 129
 130struct ExcerptChunks<'a> {
 131    content_chunks: BufferChunks<'a>,
 132    footer_height: usize,
 133}
 134
 135struct ExcerptBytes<'a> {
 136    content_bytes: language::rope::Bytes<'a>,
 137    footer_height: usize,
 138}
 139
 140impl MultiBuffer {
 141    pub fn new(replica_id: ReplicaId) -> Self {
 142        Self {
 143            snapshot: Default::default(),
 144            buffers: Default::default(),
 145            subscriptions: Default::default(),
 146            singleton: false,
 147            replica_id,
 148            history: History {
 149                next_transaction_id: Default::default(),
 150                undo_stack: Default::default(),
 151                redo_stack: Default::default(),
 152                transaction_depth: 0,
 153                group_interval: Duration::from_millis(300),
 154            },
 155        }
 156    }
 157
 158    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 159        let mut this = Self::new(buffer.read(cx).replica_id());
 160        this.singleton = true;
 161        this.push_excerpt(
 162            ExcerptProperties {
 163                buffer: &buffer,
 164                range: text::Anchor::min()..text::Anchor::max(),
 165            },
 166            cx,
 167        );
 168        this.snapshot.borrow_mut().singleton = true;
 169        this
 170    }
 171
 172    #[cfg(any(test, feature = "test-support"))]
 173    pub fn build_simple(text: &str, cx: &mut gpui::MutableAppContext) -> ModelHandle<Self> {
 174        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
 175        cx.add_model(|cx| Self::singleton(buffer, cx))
 176    }
 177
 178    #[cfg(any(test, feature = "test-support"))]
 179    pub fn build_random(
 180        mut rng: &mut impl rand::Rng,
 181        cx: &mut gpui::MutableAppContext,
 182    ) -> ModelHandle<Self> {
 183        use rand::prelude::*;
 184        use std::env;
 185        use text::RandomCharIter;
 186
 187        let max_excerpts = env::var("MAX_EXCERPTS")
 188            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
 189            .unwrap_or(5);
 190        let excerpts = rng.gen_range(1..=max_excerpts);
 191
 192        cx.add_model(|cx| {
 193            let mut multibuffer = MultiBuffer::new(0);
 194            let mut buffers = Vec::new();
 195            for _ in 0..excerpts {
 196                let buffer_handle = if rng.gen() || buffers.is_empty() {
 197                    let text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
 198                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
 199                    let buffer = buffers.last().unwrap();
 200                    log::info!(
 201                        "Creating new buffer {} with text: {:?}",
 202                        buffer.id(),
 203                        buffer.read(cx).text()
 204                    );
 205                    buffers.last().unwrap()
 206                } else {
 207                    buffers.choose(rng).unwrap()
 208                };
 209
 210                let buffer = buffer_handle.read(cx);
 211                let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
 212                let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
 213                let header_height = rng.gen_range(0..=5);
 214                log::info!(
 215                    "Inserting excerpt from buffer {} with header height {} and range {:?}: {:?}",
 216                    buffer_handle.id(),
 217                    header_height,
 218                    start_ix..end_ix,
 219                    &buffer.text()[start_ix..end_ix]
 220                );
 221
 222                multibuffer.push_excerpt(
 223                    ExcerptProperties {
 224                        buffer: buffer_handle,
 225                        range: start_ix..end_ix,
 226                    },
 227                    cx,
 228                );
 229            }
 230            multibuffer
 231        })
 232    }
 233
 234    pub fn replica_id(&self) -> ReplicaId {
 235        self.replica_id
 236    }
 237
 238    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 239        self.sync(cx);
 240        self.snapshot.borrow().clone()
 241    }
 242
 243    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 244        self.sync(cx);
 245        self.snapshot.borrow()
 246    }
 247
 248    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 249        if self.singleton {
 250            return Some(
 251                self.buffers
 252                    .borrow()
 253                    .values()
 254                    .next()
 255                    .unwrap()
 256                    .buffer
 257                    .clone(),
 258            );
 259        } else {
 260            None
 261        }
 262    }
 263
 264    pub fn subscribe(&mut self) -> Subscription {
 265        self.subscriptions.subscribe()
 266    }
 267
 268    pub fn edit<I, S, T>(&mut self, ranges: I, new_text: T, cx: &mut ModelContext<Self>)
 269    where
 270        I: IntoIterator<Item = Range<S>>,
 271        S: ToOffset,
 272        T: Into<String>,
 273    {
 274        self.edit_internal(ranges, new_text, false, cx)
 275    }
 276
 277    pub fn edit_with_autoindent<I, S, T>(
 278        &mut self,
 279        ranges: I,
 280        new_text: T,
 281        cx: &mut ModelContext<Self>,
 282    ) where
 283        I: IntoIterator<Item = Range<S>>,
 284        S: ToOffset,
 285        T: Into<String>,
 286    {
 287        self.edit_internal(ranges, new_text, true, cx)
 288    }
 289
 290    pub fn edit_internal<I, S, T>(
 291        &mut self,
 292        ranges_iter: I,
 293        new_text: T,
 294        autoindent: bool,
 295        cx: &mut ModelContext<Self>,
 296    ) where
 297        I: IntoIterator<Item = Range<S>>,
 298        S: ToOffset,
 299        T: Into<String>,
 300    {
 301        if let Some(buffer) = self.as_singleton() {
 302            let snapshot = self.read(cx);
 303            let ranges = ranges_iter
 304                .into_iter()
 305                .map(|range| range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot));
 306            return buffer.update(cx, |buffer, cx| {
 307                if autoindent {
 308                    buffer.edit_with_autoindent(ranges, new_text, cx)
 309                } else {
 310                    buffer.edit(ranges, new_text, cx)
 311                }
 312            });
 313        }
 314
 315        let snapshot = self.read(cx);
 316        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, bool)>> = Default::default();
 317        let mut cursor = snapshot.excerpts.cursor::<usize>();
 318        for range in ranges_iter {
 319            let start = range.start.to_offset(&snapshot);
 320            let end = range.end.to_offset(&snapshot);
 321            cursor.seek(&start, Bias::Right, &());
 322            if cursor.item().is_none() && start == *cursor.start() {
 323                cursor.prev(&());
 324            }
 325            let start_excerpt = cursor.item().expect("start offset out of bounds");
 326            let start_overshoot = start - cursor.start();
 327            let buffer_start =
 328                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 329
 330            cursor.seek(&end, Bias::Right, &());
 331            if cursor.item().is_none() && end == *cursor.start() {
 332                cursor.prev(&());
 333            }
 334            let end_excerpt = cursor.item().expect("end offset out of bounds");
 335            let end_overshoot = end - cursor.start();
 336            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 337
 338            if start_excerpt.id == end_excerpt.id {
 339                buffer_edits
 340                    .entry(start_excerpt.buffer_id)
 341                    .or_insert(Vec::new())
 342                    .push((buffer_start..buffer_end, true));
 343            } else {
 344                let start_excerpt_range =
 345                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 346                let end_excerpt_range =
 347                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 348                buffer_edits
 349                    .entry(start_excerpt.buffer_id)
 350                    .or_insert(Vec::new())
 351                    .push((start_excerpt_range, true));
 352                buffer_edits
 353                    .entry(end_excerpt.buffer_id)
 354                    .or_insert(Vec::new())
 355                    .push((end_excerpt_range, false));
 356
 357                cursor.seek(&start, Bias::Right, &());
 358                cursor.next(&());
 359                while let Some(excerpt) = cursor.item() {
 360                    if excerpt.id == end_excerpt.id {
 361                        break;
 362                    }
 363                    buffer_edits
 364                        .entry(excerpt.buffer_id)
 365                        .or_insert(Vec::new())
 366                        .push((excerpt.range.to_offset(&excerpt.buffer), false));
 367                    cursor.next(&());
 368                }
 369            }
 370        }
 371
 372        let new_text = new_text.into();
 373        for (buffer_id, mut edits) in buffer_edits {
 374            edits.sort_unstable_by_key(|(range, _)| range.start);
 375            self.buffers.borrow()[&buffer_id]
 376                .buffer
 377                .update(cx, |buffer, cx| {
 378                    let mut edits = edits.into_iter().peekable();
 379                    let mut insertions = Vec::new();
 380                    let mut deletions = Vec::new();
 381                    while let Some((mut range, mut is_insertion)) = edits.next() {
 382                        while let Some((next_range, next_is_insertion)) = edits.peek() {
 383                            if range.end >= next_range.start {
 384                                range.end = cmp::max(next_range.end, range.end);
 385                                is_insertion |= *next_is_insertion;
 386                                edits.next();
 387                            } else {
 388                                break;
 389                            }
 390                        }
 391
 392                        if is_insertion {
 393                            insertions.push(
 394                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 395                            );
 396                        } else if !range.is_empty() {
 397                            deletions.push(
 398                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 399                            );
 400                        }
 401                    }
 402
 403                    if autoindent {
 404                        buffer.edit_with_autoindent(deletions, "", cx);
 405                        buffer.edit_with_autoindent(insertions, new_text.clone(), cx);
 406                    } else {
 407                        buffer.edit(deletions, "", cx);
 408                        buffer.edit(insertions, new_text.clone(), cx);
 409                    }
 410                })
 411        }
 412    }
 413
 414    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 415        self.start_transaction_at(Instant::now(), cx)
 416    }
 417
 418    pub(crate) fn start_transaction_at(
 419        &mut self,
 420        now: Instant,
 421        cx: &mut ModelContext<Self>,
 422    ) -> Option<TransactionId> {
 423        if let Some(buffer) = self.as_singleton() {
 424            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 425        }
 426
 427        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 428            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 429        }
 430        self.history.start_transaction(now)
 431    }
 432
 433    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 434        self.end_transaction_at(Instant::now(), cx)
 435    }
 436
 437    pub(crate) fn end_transaction_at(
 438        &mut self,
 439        now: Instant,
 440        cx: &mut ModelContext<Self>,
 441    ) -> Option<TransactionId> {
 442        if let Some(buffer) = self.as_singleton() {
 443            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 444        }
 445
 446        let mut buffer_transactions = HashSet::default();
 447        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 448            if let Some(transaction_id) =
 449                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 450            {
 451                buffer_transactions.insert((buffer.id(), transaction_id));
 452            }
 453        }
 454
 455        if self.history.end_transaction(now, buffer_transactions) {
 456            let transaction_id = self.history.group().unwrap();
 457            Some(transaction_id)
 458        } else {
 459            None
 460        }
 461    }
 462
 463    pub fn avoid_grouping_next_transaction(&mut self, cx: &mut ModelContext<Self>) {
 464        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 465            buffer.update(cx, |buffer, _| buffer.avoid_grouping_next_transaction());
 466        }
 467    }
 468
 469    pub fn set_active_selections(
 470        &mut self,
 471        selections: &[Selection<Anchor>],
 472        cx: &mut ModelContext<Self>,
 473    ) {
 474        let mut selections_by_buffer: HashMap<usize, Vec<Selection<text::Anchor>>> =
 475            Default::default();
 476        let snapshot = self.read(cx);
 477        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 478        for selection in selections {
 479            cursor.seek(&Some(&selection.start.excerpt_id), Bias::Left, &());
 480            while let Some(excerpt) = cursor.item() {
 481                if excerpt.id > selection.end.excerpt_id {
 482                    break;
 483                }
 484
 485                let mut start = excerpt.range.start.clone();
 486                let mut end = excerpt.range.end.clone();
 487                if excerpt.id == selection.start.excerpt_id {
 488                    start = selection.start.text_anchor.clone();
 489                }
 490                if excerpt.id == selection.end.excerpt_id {
 491                    end = selection.end.text_anchor.clone();
 492                }
 493                selections_by_buffer
 494                    .entry(excerpt.buffer_id)
 495                    .or_default()
 496                    .push(Selection {
 497                        id: selection.id,
 498                        start,
 499                        end,
 500                        reversed: selection.reversed,
 501                        goal: selection.goal,
 502                    });
 503
 504                cursor.next(&());
 505            }
 506        }
 507
 508        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 509            if !selections_by_buffer.contains_key(buffer_id) {
 510                buffer_state
 511                    .buffer
 512                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 513            }
 514        }
 515
 516        for (buffer_id, mut selections) in selections_by_buffer {
 517            self.buffers.borrow()[&buffer_id]
 518                .buffer
 519                .update(cx, |buffer, cx| {
 520                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer).unwrap());
 521                    let mut selections = selections.into_iter().peekable();
 522                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 523                        let mut selection = selections.next()?;
 524                        while let Some(next_selection) = selections.peek() {
 525                            if selection
 526                                .end
 527                                .cmp(&next_selection.start, buffer)
 528                                .unwrap()
 529                                .is_ge()
 530                            {
 531                                let next_selection = selections.next().unwrap();
 532                                if next_selection
 533                                    .end
 534                                    .cmp(&selection.end, buffer)
 535                                    .unwrap()
 536                                    .is_ge()
 537                                {
 538                                    selection.end = next_selection.end;
 539                                }
 540                            } else {
 541                                break;
 542                            }
 543                        }
 544                        Some(selection)
 545                    }));
 546                    buffer.set_active_selections(merged_selections, cx);
 547                });
 548        }
 549    }
 550
 551    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 552        for buffer in self.buffers.borrow().values() {
 553            buffer
 554                .buffer
 555                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 556        }
 557    }
 558
 559    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 560        if let Some(buffer) = self.as_singleton() {
 561            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 562        }
 563
 564        while let Some(transaction) = self.history.pop_undo() {
 565            let mut undone = false;
 566            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 567                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 568                    undone |= buffer.update(cx, |buf, cx| {
 569                        buf.undo_transaction(*buffer_transaction_id, cx)
 570                    });
 571                }
 572            }
 573
 574            if undone {
 575                return Some(transaction.id);
 576            }
 577        }
 578
 579        None
 580    }
 581
 582    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 583        if let Some(buffer) = self.as_singleton() {
 584            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 585        }
 586
 587        while let Some(transaction) = self.history.pop_redo() {
 588            let mut redone = false;
 589            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 590                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 591                    redone |= buffer.update(cx, |buf, cx| {
 592                        buf.redo_transaction(*buffer_transaction_id, cx)
 593                    });
 594                }
 595            }
 596
 597            if redone {
 598                return Some(transaction.id);
 599            }
 600        }
 601
 602        None
 603    }
 604
 605    pub fn push_excerpt<O>(
 606        &mut self,
 607        props: ExcerptProperties<O>,
 608        cx: &mut ModelContext<Self>,
 609    ) -> ExcerptId
 610    where
 611        O: text::ToOffset,
 612    {
 613        self.insert_excerpt_after(&ExcerptId::max(), props, cx)
 614    }
 615
 616    pub fn insert_excerpt_after<O>(
 617        &mut self,
 618        prev_excerpt_id: &ExcerptId,
 619        props: ExcerptProperties<O>,
 620        cx: &mut ModelContext<Self>,
 621    ) -> ExcerptId
 622    where
 623        O: text::ToOffset,
 624    {
 625        assert_eq!(self.history.transaction_depth, 0);
 626        self.sync(cx);
 627
 628        let buffer_snapshot = props.buffer.read(cx).snapshot();
 629        let range = buffer_snapshot.anchor_before(&props.range.start)
 630            ..buffer_snapshot.anchor_after(&props.range.end);
 631        let mut snapshot = self.snapshot.borrow_mut();
 632        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 633        let mut new_excerpts = cursor.slice(&Some(prev_excerpt_id), Bias::Right, &());
 634
 635        let mut prev_id = ExcerptId::min();
 636        let edit_start = new_excerpts.summary().text.bytes;
 637        new_excerpts.update_last(
 638            |excerpt| {
 639                excerpt.has_trailing_newline = true;
 640                prev_id = excerpt.id.clone();
 641            },
 642            &(),
 643        );
 644
 645        let mut next_id = ExcerptId::max();
 646        if let Some(next_excerpt) = cursor.item() {
 647            next_id = next_excerpt.id.clone();
 648        }
 649
 650        let id = ExcerptId::between(&prev_id, &next_id);
 651
 652        let mut buffers = self.buffers.borrow_mut();
 653        let buffer_state = buffers
 654            .entry(props.buffer.id())
 655            .or_insert_with(|| BufferState {
 656                last_version: buffer_snapshot.version().clone(),
 657                last_parse_count: buffer_snapshot.parse_count(),
 658                last_selections_update_count: buffer_snapshot.selections_update_count(),
 659                last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 660                excerpts: Default::default(),
 661                _subscriptions: [
 662                    cx.observe(&props.buffer, |_, _, cx| cx.notify()),
 663                    cx.subscribe(&props.buffer, Self::on_buffer_event),
 664                ],
 665                buffer: props.buffer.clone(),
 666            });
 667        if let Err(ix) = buffer_state.excerpts.binary_search(&id) {
 668            buffer_state.excerpts.insert(ix, id.clone());
 669        }
 670
 671        let excerpt = Excerpt::new(
 672            id.clone(),
 673            props.buffer.id(),
 674            buffer_snapshot,
 675            range,
 676            cursor.item().is_some(),
 677        );
 678        new_excerpts.push(excerpt, &());
 679        let edit_end = new_excerpts.summary().text.bytes;
 680
 681        new_excerpts.push_tree(cursor.suffix(&()), &());
 682        drop(cursor);
 683        snapshot.excerpts = new_excerpts;
 684
 685        self.subscriptions.publish_mut([Edit {
 686            old: edit_start..edit_start,
 687            new: edit_start..edit_end,
 688        }]);
 689
 690        cx.notify();
 691        id
 692    }
 693
 694    pub fn excerpt_ids_for_buffer(&self, buffer: &ModelHandle<Buffer>) -> Vec<ExcerptId> {
 695        self.buffers
 696            .borrow()
 697            .get(&buffer.id())
 698            .map_or(Vec::new(), |state| state.excerpts.clone())
 699    }
 700
 701    pub fn excerpted_buffers<'a, T: ToOffset>(
 702        &'a self,
 703        range: Range<T>,
 704        cx: &AppContext,
 705    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 706        let snapshot = self.snapshot(cx);
 707        let start = range.start.to_offset(&snapshot);
 708        let end = range.end.to_offset(&snapshot);
 709
 710        let mut result = Vec::new();
 711        let mut cursor = snapshot.excerpts.cursor::<usize>();
 712        cursor.seek(&start, Bias::Right, &());
 713        while let Some(excerpt) = cursor.item() {
 714            if *cursor.start() > end {
 715                break;
 716            }
 717
 718            let mut end_before_newline = cursor.end(&());
 719            if excerpt.has_trailing_newline {
 720                end_before_newline -= 1;
 721            }
 722            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 723            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 724            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 725            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 726            result.push((buffer, start..end));
 727            cursor.next(&());
 728        }
 729
 730        result
 731    }
 732
 733    pub fn remove_excerpts<'a>(
 734        &mut self,
 735        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 736        cx: &mut ModelContext<Self>,
 737    ) {
 738        let mut buffers = self.buffers.borrow_mut();
 739        let mut snapshot = self.snapshot.borrow_mut();
 740        let mut new_excerpts = SumTree::new();
 741        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 742        let mut edits = Vec::new();
 743        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 744
 745        while let Some(mut excerpt_id) = excerpt_ids.next() {
 746            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 747            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 748            if let Some(mut excerpt) = cursor.item() {
 749                if excerpt.id != *excerpt_id {
 750                    continue;
 751                }
 752                let mut old_start = cursor.start().1;
 753
 754                // Skip over the removed excerpt.
 755                loop {
 756                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 757                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 758                        if buffer_state.excerpts.is_empty() {
 759                            buffers.remove(&excerpt.buffer_id);
 760                        }
 761                    }
 762                    cursor.next(&());
 763
 764                    // Skip over any subsequent excerpts that are also removed.
 765                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 766                        if let Some(next_excerpt) = cursor.item() {
 767                            if next_excerpt.id == *next_excerpt_id {
 768                                excerpt = next_excerpt;
 769                                excerpt_id = excerpt_ids.next().unwrap();
 770                                continue;
 771                            }
 772                        }
 773                    }
 774
 775                    break;
 776                }
 777
 778                // When removing the last excerpt, remove the trailing newline from
 779                // the previous excerpt.
 780                if cursor.item().is_none() && old_start > 0 {
 781                    old_start -= 1;
 782                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 783                }
 784
 785                // Push an edit for the removal of this run of excerpts.
 786                let old_end = cursor.start().1;
 787                let new_start = new_excerpts.summary().text.bytes;
 788                edits.push(Edit {
 789                    old: old_start..old_end,
 790                    new: new_start..new_start,
 791                });
 792            }
 793        }
 794        new_excerpts.push_tree(cursor.suffix(&()), &());
 795        drop(cursor);
 796        snapshot.excerpts = new_excerpts;
 797        self.subscriptions.publish_mut(edits);
 798        cx.notify();
 799    }
 800
 801    pub fn text_anchor_for_position<'a, T: ToOffset>(
 802        &'a self,
 803        position: T,
 804        cx: &AppContext,
 805    ) -> (ModelHandle<Buffer>, language::Anchor) {
 806        let snapshot = self.read(cx);
 807        let anchor = snapshot.anchor_before(position);
 808        (
 809            self.buffers.borrow()[&anchor.buffer_id].buffer.clone(),
 810            anchor.text_anchor,
 811        )
 812    }
 813
 814    fn on_buffer_event(
 815        &mut self,
 816        _: ModelHandle<Buffer>,
 817        event: &Event,
 818        cx: &mut ModelContext<Self>,
 819    ) {
 820        cx.emit(event.clone());
 821    }
 822
 823    pub fn format(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 824        let mut format_tasks = Vec::new();
 825        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 826            format_tasks.push(buffer.update(cx, |buffer, cx| buffer.format(cx)));
 827        }
 828
 829        cx.spawn(|_, _| async move {
 830            for format in format_tasks {
 831                format.await?;
 832            }
 833            Ok(())
 834        })
 835    }
 836
 837    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 838        let mut save_tasks = Vec::new();
 839        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 840            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx)));
 841        }
 842
 843        cx.spawn(|_, _| async move {
 844            for save in save_tasks {
 845                save.await?;
 846            }
 847            Ok(())
 848        })
 849    }
 850
 851    pub fn completions<T>(
 852        &self,
 853        position: T,
 854        cx: &mut ModelContext<Self>,
 855    ) -> Task<Result<Vec<Completion>>>
 856    where
 857        T: ToOffset,
 858    {
 859        let (buffer, text_anchor) = self.text_anchor_for_position(position, cx);
 860        buffer.update(cx, |buffer, cx| buffer.completions(text_anchor, cx))
 861    }
 862
 863    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 864        self.buffers
 865            .borrow()
 866            .values()
 867            .next()
 868            .and_then(|state| state.buffer.read(cx).language())
 869    }
 870
 871    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 872        self.as_singleton()?.read(cx).file()
 873    }
 874
 875    #[cfg(test)]
 876    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 877        self.as_singleton().unwrap().read(cx).is_parsing()
 878    }
 879
 880    fn sync(&self, cx: &AppContext) {
 881        let mut snapshot = self.snapshot.borrow_mut();
 882        let mut excerpts_to_edit = Vec::new();
 883        let mut reparsed = false;
 884        let mut diagnostics_updated = false;
 885        let mut is_dirty = false;
 886        let mut has_conflict = false;
 887        let mut buffers = self.buffers.borrow_mut();
 888        for buffer_state in buffers.values_mut() {
 889            let buffer = buffer_state.buffer.read(cx);
 890            let version = buffer.version();
 891            let parse_count = buffer.parse_count();
 892            let selections_update_count = buffer.selections_update_count();
 893            let diagnostics_update_count = buffer.diagnostics_update_count();
 894
 895            let buffer_edited = version.changed_since(&buffer_state.last_version);
 896            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
 897            let buffer_selections_updated =
 898                selections_update_count > buffer_state.last_selections_update_count;
 899            let buffer_diagnostics_updated =
 900                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
 901            if buffer_edited
 902                || buffer_reparsed
 903                || buffer_selections_updated
 904                || buffer_diagnostics_updated
 905            {
 906                buffer_state.last_version = version;
 907                buffer_state.last_parse_count = parse_count;
 908                buffer_state.last_selections_update_count = selections_update_count;
 909                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
 910                excerpts_to_edit.extend(
 911                    buffer_state
 912                        .excerpts
 913                        .iter()
 914                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
 915                );
 916            }
 917
 918            reparsed |= buffer_reparsed;
 919            diagnostics_updated |= buffer_diagnostics_updated;
 920            is_dirty |= buffer.is_dirty();
 921            has_conflict |= buffer.has_conflict();
 922        }
 923        if reparsed {
 924            snapshot.parse_count += 1;
 925        }
 926        if diagnostics_updated {
 927            snapshot.diagnostics_update_count += 1;
 928        }
 929        snapshot.is_dirty = is_dirty;
 930        snapshot.has_conflict = has_conflict;
 931
 932        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
 933
 934        let mut edits = Vec::new();
 935        let mut new_excerpts = SumTree::new();
 936        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 937
 938        for (id, buffer, buffer_edited) in excerpts_to_edit {
 939            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
 940            let old_excerpt = cursor.item().unwrap();
 941            let buffer_id = buffer.id();
 942            let buffer = buffer.read(cx);
 943
 944            let mut new_excerpt;
 945            if buffer_edited {
 946                edits.extend(
 947                    buffer
 948                        .edits_since_in_range::<usize>(
 949                            old_excerpt.buffer.version(),
 950                            old_excerpt.range.clone(),
 951                        )
 952                        .map(|mut edit| {
 953                            let excerpt_old_start = cursor.start().1;
 954                            let excerpt_new_start = new_excerpts.summary().text.bytes;
 955                            edit.old.start += excerpt_old_start;
 956                            edit.old.end += excerpt_old_start;
 957                            edit.new.start += excerpt_new_start;
 958                            edit.new.end += excerpt_new_start;
 959                            edit
 960                        }),
 961                );
 962
 963                new_excerpt = Excerpt::new(
 964                    id.clone(),
 965                    buffer_id,
 966                    buffer.snapshot(),
 967                    old_excerpt.range.clone(),
 968                    old_excerpt.has_trailing_newline,
 969                );
 970            } else {
 971                new_excerpt = old_excerpt.clone();
 972                new_excerpt.buffer = buffer.snapshot();
 973            }
 974
 975            new_excerpts.push(new_excerpt, &());
 976            cursor.next(&());
 977        }
 978        new_excerpts.push_tree(cursor.suffix(&()), &());
 979
 980        drop(cursor);
 981        snapshot.excerpts = new_excerpts;
 982
 983        self.subscriptions.publish(edits);
 984    }
 985}
 986
 987#[cfg(any(test, feature = "test-support"))]
 988impl MultiBuffer {
 989    pub fn randomly_edit(
 990        &mut self,
 991        rng: &mut impl rand::Rng,
 992        count: usize,
 993        cx: &mut ModelContext<Self>,
 994    ) {
 995        use text::RandomCharIter;
 996
 997        let snapshot = self.read(cx);
 998        let mut old_ranges: Vec<Range<usize>> = Vec::new();
 999        for _ in 0..count {
1000            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
1001            if last_end > snapshot.len() {
1002                break;
1003            }
1004            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
1005            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1006            old_ranges.push(start_ix..end_ix);
1007        }
1008        let new_text_len = rng.gen_range(0..10);
1009        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1010        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
1011        drop(snapshot);
1012
1013        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
1014    }
1015}
1016
1017impl Entity for MultiBuffer {
1018    type Event = language::Event;
1019}
1020
1021impl MultiBufferSnapshot {
1022    pub fn text(&self) -> String {
1023        self.chunks(0..self.len(), None)
1024            .map(|chunk| chunk.text)
1025            .collect()
1026    }
1027
1028    pub fn reversed_chars_at<'a, T: ToOffset>(
1029        &'a self,
1030        position: T,
1031    ) -> impl Iterator<Item = char> + 'a {
1032        let mut offset = position.to_offset(self);
1033        let mut cursor = self.excerpts.cursor::<usize>();
1034        cursor.seek(&offset, Bias::Left, &());
1035        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1036            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1037            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1038            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1039            excerpt.buffer.reversed_chunks_in_range(start..end)
1040        });
1041        iter::from_fn(move || {
1042            if offset == *cursor.start() {
1043                cursor.prev(&());
1044                let excerpt = cursor.item()?;
1045                excerpt_chunks = Some(
1046                    excerpt
1047                        .buffer
1048                        .reversed_chunks_in_range(excerpt.range.clone()),
1049                );
1050            }
1051
1052            let excerpt = cursor.item().unwrap();
1053            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1054                offset -= 1;
1055                Some("\n")
1056            } else {
1057                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1058                offset -= chunk.len();
1059                Some(chunk)
1060            }
1061        })
1062        .flat_map(|c| c.chars().rev())
1063    }
1064
1065    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1066        let offset = position.to_offset(self);
1067        self.text_for_range(offset..self.len())
1068            .flat_map(|chunk| chunk.chars())
1069    }
1070
1071    pub fn text_for_range<'a, T: ToOffset>(
1072        &'a self,
1073        range: Range<T>,
1074    ) -> impl Iterator<Item = &'a str> {
1075        self.chunks(range, None).map(|chunk| chunk.text)
1076    }
1077
1078    pub fn is_line_blank(&self, row: u32) -> bool {
1079        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1080            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1081    }
1082
1083    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1084    where
1085        T: ToOffset,
1086    {
1087        let position = position.to_offset(self);
1088        position == self.clip_offset(position, Bias::Left)
1089            && self
1090                .bytes_in_range(position..self.len())
1091                .flatten()
1092                .copied()
1093                .take(needle.len())
1094                .eq(needle.bytes())
1095    }
1096
1097    fn as_singleton(&self) -> Option<&Excerpt> {
1098        if self.singleton {
1099            self.excerpts.iter().next()
1100        } else {
1101            None
1102        }
1103    }
1104
1105    pub fn len(&self) -> usize {
1106        self.excerpts.summary().text.bytes
1107    }
1108
1109    pub fn max_buffer_row(&self) -> u32 {
1110        self.excerpts.summary().max_buffer_row
1111    }
1112
1113    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1114        if let Some(excerpt) = self.as_singleton() {
1115            return excerpt.buffer.clip_offset(offset, bias);
1116        }
1117
1118        let mut cursor = self.excerpts.cursor::<usize>();
1119        cursor.seek(&offset, Bias::Right, &());
1120        let overshoot = if let Some(excerpt) = cursor.item() {
1121            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1122            let buffer_offset = excerpt
1123                .buffer
1124                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1125            buffer_offset.saturating_sub(excerpt_start)
1126        } else {
1127            0
1128        };
1129        cursor.start() + overshoot
1130    }
1131
1132    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1133        if let Some(excerpt) = self.as_singleton() {
1134            return excerpt.buffer.clip_point(point, bias);
1135        }
1136
1137        let mut cursor = self.excerpts.cursor::<Point>();
1138        cursor.seek(&point, Bias::Right, &());
1139        let overshoot = if let Some(excerpt) = cursor.item() {
1140            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1141            let buffer_point = excerpt
1142                .buffer
1143                .clip_point(excerpt_start + (point - cursor.start()), bias);
1144            buffer_point.saturating_sub(excerpt_start)
1145        } else {
1146            Point::zero()
1147        };
1148        *cursor.start() + overshoot
1149    }
1150
1151    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1152        if let Some(excerpt) = self.as_singleton() {
1153            return excerpt.buffer.clip_point_utf16(point, bias);
1154        }
1155
1156        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1157        cursor.seek(&point, Bias::Right, &());
1158        let overshoot = if let Some(excerpt) = cursor.item() {
1159            let excerpt_start = excerpt
1160                .buffer
1161                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1162            let buffer_point = excerpt
1163                .buffer
1164                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1165            buffer_point.saturating_sub(excerpt_start)
1166        } else {
1167            PointUtf16::zero()
1168        };
1169        *cursor.start() + overshoot
1170    }
1171
1172    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1173        let range = range.start.to_offset(self)..range.end.to_offset(self);
1174        let mut excerpts = self.excerpts.cursor::<usize>();
1175        excerpts.seek(&range.start, Bias::Right, &());
1176
1177        let mut chunk = &[][..];
1178        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1179            let mut excerpt_bytes = excerpt
1180                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1181            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1182            Some(excerpt_bytes)
1183        } else {
1184            None
1185        };
1186
1187        MultiBufferBytes {
1188            range,
1189            excerpts,
1190            excerpt_bytes,
1191            chunk,
1192        }
1193    }
1194
1195    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1196        let mut result = MultiBufferRows {
1197            buffer_row_range: 0..0,
1198            excerpts: self.excerpts.cursor(),
1199        };
1200        result.seek(start_row);
1201        result
1202    }
1203
1204    pub fn chunks<'a, T: ToOffset>(
1205        &'a self,
1206        range: Range<T>,
1207        theme: Option<&'a SyntaxTheme>,
1208    ) -> MultiBufferChunks<'a> {
1209        let range = range.start.to_offset(self)..range.end.to_offset(self);
1210        let mut chunks = MultiBufferChunks {
1211            range: range.clone(),
1212            excerpts: self.excerpts.cursor(),
1213            excerpt_chunks: None,
1214            theme,
1215        };
1216        chunks.seek(range.start);
1217        chunks
1218    }
1219
1220    pub fn offset_to_point(&self, offset: usize) -> Point {
1221        if let Some(excerpt) = self.as_singleton() {
1222            return excerpt.buffer.offset_to_point(offset);
1223        }
1224
1225        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1226        cursor.seek(&offset, Bias::Right, &());
1227        if let Some(excerpt) = cursor.item() {
1228            let (start_offset, start_point) = cursor.start();
1229            let overshoot = offset - start_offset;
1230            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1231            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1232            let buffer_point = excerpt
1233                .buffer
1234                .offset_to_point(excerpt_start_offset + overshoot);
1235            *start_point + (buffer_point - excerpt_start_point)
1236        } else {
1237            self.excerpts.summary().text.lines
1238        }
1239    }
1240
1241    pub fn point_to_offset(&self, point: Point) -> usize {
1242        if let Some(excerpt) = self.as_singleton() {
1243            return excerpt.buffer.point_to_offset(point);
1244        }
1245
1246        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1247        cursor.seek(&point, Bias::Right, &());
1248        if let Some(excerpt) = cursor.item() {
1249            let (start_point, start_offset) = cursor.start();
1250            let overshoot = point - start_point;
1251            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1252            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1253            let buffer_offset = excerpt
1254                .buffer
1255                .point_to_offset(excerpt_start_point + overshoot);
1256            *start_offset + buffer_offset - excerpt_start_offset
1257        } else {
1258            self.excerpts.summary().text.bytes
1259        }
1260    }
1261
1262    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1263        if let Some(excerpt) = self.as_singleton() {
1264            return excerpt.buffer.point_utf16_to_offset(point);
1265        }
1266
1267        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1268        cursor.seek(&point, Bias::Right, &());
1269        if let Some(excerpt) = cursor.item() {
1270            let (start_point, start_offset) = cursor.start();
1271            let overshoot = point - start_point;
1272            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1273            let excerpt_start_point = excerpt
1274                .buffer
1275                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1276            let buffer_offset = excerpt
1277                .buffer
1278                .point_utf16_to_offset(excerpt_start_point + overshoot);
1279            *start_offset + (buffer_offset - excerpt_start_offset)
1280        } else {
1281            self.excerpts.summary().text.bytes
1282        }
1283    }
1284
1285    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1286        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1287            buffer
1288                .indent_column_for_line(range.start.row)
1289                .min(range.end.column)
1290                .saturating_sub(range.start.column)
1291        } else {
1292            0
1293        }
1294    }
1295
1296    pub fn line_len(&self, row: u32) -> u32 {
1297        if let Some((_, range)) = self.buffer_line_for_row(row) {
1298            range.end.column - range.start.column
1299        } else {
1300            0
1301        }
1302    }
1303
1304    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1305        let mut cursor = self.excerpts.cursor::<Point>();
1306        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1307        if let Some(excerpt) = cursor.item() {
1308            let overshoot = row - cursor.start().row;
1309            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1310            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1311            let buffer_row = excerpt_start.row + overshoot;
1312            let line_start = Point::new(buffer_row, 0);
1313            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1314            return Some((
1315                &excerpt.buffer,
1316                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1317            ));
1318        }
1319        None
1320    }
1321
1322    pub fn max_point(&self) -> Point {
1323        self.text_summary().lines
1324    }
1325
1326    pub fn text_summary(&self) -> TextSummary {
1327        self.excerpts.summary().text
1328    }
1329
1330    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1331    where
1332        D: TextDimension,
1333        O: ToOffset,
1334    {
1335        let mut summary = D::default();
1336        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1337        let mut cursor = self.excerpts.cursor::<usize>();
1338        cursor.seek(&range.start, Bias::Right, &());
1339        if let Some(excerpt) = cursor.item() {
1340            let mut end_before_newline = cursor.end(&());
1341            if excerpt.has_trailing_newline {
1342                end_before_newline -= 1;
1343            }
1344
1345            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1346            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1347            let end_in_excerpt =
1348                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1349            summary.add_assign(
1350                &excerpt
1351                    .buffer
1352                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1353            );
1354
1355            if range.end > end_before_newline {
1356                summary.add_assign(&D::from_text_summary(&TextSummary {
1357                    bytes: 1,
1358                    lines: Point::new(1 as u32, 0),
1359                    lines_utf16: PointUtf16::new(1 as u32, 0),
1360                    first_line_chars: 0,
1361                    last_line_chars: 0,
1362                    longest_row: 0,
1363                    longest_row_chars: 0,
1364                }));
1365            }
1366
1367            cursor.next(&());
1368        }
1369
1370        if range.end > *cursor.start() {
1371            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1372                &range.end,
1373                Bias::Right,
1374                &(),
1375            )));
1376            if let Some(excerpt) = cursor.item() {
1377                range.end = cmp::max(*cursor.start(), range.end);
1378
1379                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1380                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1381                summary.add_assign(
1382                    &excerpt
1383                        .buffer
1384                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1385                );
1386            }
1387        }
1388
1389        summary
1390    }
1391
1392    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1393    where
1394        D: TextDimension + Ord + Sub<D, Output = D>,
1395    {
1396        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1397        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1398        if cursor.item().is_none() {
1399            cursor.next(&());
1400        }
1401
1402        let mut position = D::from_text_summary(&cursor.start().text);
1403        if let Some(excerpt) = cursor.item() {
1404            if excerpt.id == anchor.excerpt_id && excerpt.buffer_id == anchor.buffer_id {
1405                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1406                let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1407                let buffer_position = cmp::min(
1408                    excerpt_buffer_end,
1409                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
1410                );
1411                if buffer_position > excerpt_buffer_start {
1412                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1413                }
1414            }
1415        }
1416        position
1417    }
1418
1419    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1420    where
1421        D: TextDimension + Ord + Sub<D, Output = D>,
1422        I: 'a + IntoIterator<Item = &'a Anchor>,
1423    {
1424        let mut anchors = anchors.into_iter().peekable();
1425        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1426        let mut summaries = Vec::new();
1427        while let Some(anchor) = anchors.peek() {
1428            let excerpt_id = &anchor.excerpt_id;
1429            let buffer_id = anchor.buffer_id;
1430            let excerpt_anchors = iter::from_fn(|| {
1431                let anchor = anchors.peek()?;
1432                if anchor.excerpt_id == *excerpt_id && anchor.buffer_id == buffer_id {
1433                    Some(&anchors.next().unwrap().text_anchor)
1434                } else {
1435                    None
1436                }
1437            });
1438
1439            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1440            if cursor.item().is_none() {
1441                cursor.next(&());
1442            }
1443
1444            let position = D::from_text_summary(&cursor.start().text);
1445            if let Some(excerpt) = cursor.item() {
1446                if excerpt.id == *excerpt_id && excerpt.buffer_id == buffer_id {
1447                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1448                    let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1449                    summaries.extend(
1450                        excerpt
1451                            .buffer
1452                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1453                            .map(move |summary| {
1454                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
1455                                let mut position = position.clone();
1456                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1457                                if summary > excerpt_buffer_start {
1458                                    position.add_assign(&(summary - excerpt_buffer_start));
1459                                }
1460                                position
1461                            }),
1462                    );
1463                    continue;
1464                }
1465            }
1466
1467            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1468        }
1469
1470        summaries
1471    }
1472
1473    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1474    where
1475        I: 'a + IntoIterator<Item = &'a Anchor>,
1476    {
1477        let mut anchors = anchors.into_iter().enumerate().peekable();
1478        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1479        let mut result = Vec::new();
1480        while let Some((_, anchor)) = anchors.peek() {
1481            let old_excerpt_id = &anchor.excerpt_id;
1482
1483            // Find the location where this anchor's excerpt should be.
1484            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1485            if cursor.item().is_none() {
1486                cursor.next(&());
1487            }
1488
1489            let next_excerpt = cursor.item();
1490            let prev_excerpt = cursor.prev_item();
1491
1492            // Process all of the anchors for this excerpt.
1493            while let Some((_, anchor)) = anchors.peek() {
1494                if anchor.excerpt_id != *old_excerpt_id {
1495                    break;
1496                }
1497                let mut kept_position = false;
1498                let (anchor_ix, anchor) = anchors.next().unwrap();
1499                let mut anchor = anchor.clone();
1500
1501                // Leave min and max anchors unchanged.
1502                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1503                    kept_position = true;
1504                }
1505                // If the old excerpt still exists at this location, then leave
1506                // the anchor unchanged.
1507                else if next_excerpt.map_or(false, |excerpt| {
1508                    excerpt.id == *old_excerpt_id && excerpt.contains(&anchor)
1509                }) {
1510                    kept_position = true;
1511                }
1512                // If the old excerpt no longer exists at this location, then attempt to
1513                // find an equivalent position for this anchor in an adjacent excerpt.
1514                else {
1515                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1516                        if excerpt.contains(&anchor) {
1517                            anchor.excerpt_id = excerpt.id.clone();
1518                            kept_position = true;
1519                            break;
1520                        }
1521                    }
1522                }
1523                // If there's no adjacent excerpt that contains the anchor's position,
1524                // then report that the anchor has lost its position.
1525                if !kept_position {
1526                    anchor = if let Some(excerpt) = next_excerpt {
1527                        let mut text_anchor = excerpt
1528                            .range
1529                            .start
1530                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1531                        if text_anchor
1532                            .cmp(&excerpt.range.end, &excerpt.buffer)
1533                            .unwrap()
1534                            .is_gt()
1535                        {
1536                            text_anchor = excerpt.range.end.clone();
1537                        }
1538                        Anchor {
1539                            buffer_id: excerpt.buffer_id,
1540                            excerpt_id: excerpt.id.clone(),
1541                            text_anchor,
1542                        }
1543                    } else if let Some(excerpt) = prev_excerpt {
1544                        let mut text_anchor = excerpt
1545                            .range
1546                            .end
1547                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1548                        if text_anchor
1549                            .cmp(&excerpt.range.start, &excerpt.buffer)
1550                            .unwrap()
1551                            .is_lt()
1552                        {
1553                            text_anchor = excerpt.range.start.clone();
1554                        }
1555                        Anchor {
1556                            buffer_id: excerpt.buffer_id,
1557                            excerpt_id: excerpt.id.clone(),
1558                            text_anchor,
1559                        }
1560                    } else if anchor.text_anchor.bias == Bias::Left {
1561                        Anchor::min()
1562                    } else {
1563                        Anchor::max()
1564                    };
1565                }
1566
1567                result.push((anchor_ix, anchor, kept_position));
1568            }
1569        }
1570        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self).unwrap());
1571        result
1572    }
1573
1574    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1575        self.anchor_at(position, Bias::Left)
1576    }
1577
1578    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1579        self.anchor_at(position, Bias::Right)
1580    }
1581
1582    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1583        let offset = position.to_offset(self);
1584        if let Some(excerpt) = self.as_singleton() {
1585            return Anchor {
1586                buffer_id: excerpt.buffer_id,
1587                excerpt_id: excerpt.id.clone(),
1588                text_anchor: excerpt.buffer.anchor_at(offset, bias),
1589            };
1590        }
1591
1592        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1593        cursor.seek(&offset, Bias::Right, &());
1594        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1595            cursor.prev(&());
1596        }
1597        if let Some(excerpt) = cursor.item() {
1598            let mut overshoot = offset.saturating_sub(cursor.start().0);
1599            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1600                overshoot -= 1;
1601                bias = Bias::Right;
1602            }
1603
1604            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1605            let text_anchor =
1606                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1607            Anchor {
1608                buffer_id: excerpt.buffer_id,
1609                excerpt_id: excerpt.id.clone(),
1610                text_anchor,
1611            }
1612        } else if offset == 0 && bias == Bias::Left {
1613            Anchor::min()
1614        } else {
1615            Anchor::max()
1616        }
1617    }
1618
1619    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1620        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1621        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1622        if let Some(excerpt) = cursor.item() {
1623            if excerpt.id == excerpt_id {
1624                let text_anchor = excerpt.clip_anchor(text_anchor);
1625                drop(cursor);
1626                return Anchor {
1627                    buffer_id: excerpt.buffer_id,
1628                    excerpt_id,
1629                    text_anchor,
1630                };
1631            }
1632        }
1633        panic!("excerpt not found");
1634    }
1635
1636    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
1637        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
1638            true
1639        } else if let Some((buffer_id, buffer_snapshot)) =
1640            self.buffer_snapshot_for_excerpt(&anchor.excerpt_id)
1641        {
1642            anchor.buffer_id == buffer_id && buffer_snapshot.can_resolve(&anchor.text_anchor)
1643        } else {
1644            false
1645        }
1646    }
1647
1648    pub fn range_contains_excerpt_boundary<T: ToOffset>(&self, range: Range<T>) -> bool {
1649        let start = range.start.to_offset(self);
1650        let end = range.end.to_offset(self);
1651        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1652        cursor.seek(&start, Bias::Right, &());
1653        let start_id = cursor
1654            .item()
1655            .or_else(|| cursor.prev_item())
1656            .map(|excerpt| &excerpt.id);
1657        cursor.seek_forward(&end, Bias::Right, &());
1658        let end_id = cursor
1659            .item()
1660            .or_else(|| cursor.prev_item())
1661            .map(|excerpt| &excerpt.id);
1662        start_id != end_id
1663    }
1664
1665    pub fn parse_count(&self) -> usize {
1666        self.parse_count
1667    }
1668
1669    pub fn enclosing_bracket_ranges<T: ToOffset>(
1670        &self,
1671        range: Range<T>,
1672    ) -> Option<(Range<usize>, Range<usize>)> {
1673        let range = range.start.to_offset(self)..range.end.to_offset(self);
1674
1675        let mut cursor = self.excerpts.cursor::<usize>();
1676        cursor.seek(&range.start, Bias::Right, &());
1677        let start_excerpt = cursor.item();
1678
1679        cursor.seek(&range.end, Bias::Right, &());
1680        let end_excerpt = cursor.item();
1681
1682        start_excerpt
1683            .zip(end_excerpt)
1684            .and_then(|(start_excerpt, end_excerpt)| {
1685                if start_excerpt.id != end_excerpt.id {
1686                    return None;
1687                }
1688
1689                let excerpt_buffer_start =
1690                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1691                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1692
1693                let start_in_buffer =
1694                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1695                let end_in_buffer =
1696                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1697                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
1698                    .buffer
1699                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
1700
1701                if start_bracket_range.start >= excerpt_buffer_start
1702                    && end_bracket_range.end < excerpt_buffer_end
1703                {
1704                    start_bracket_range.start =
1705                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
1706                    start_bracket_range.end =
1707                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
1708                    end_bracket_range.start =
1709                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
1710                    end_bracket_range.end =
1711                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
1712                    Some((start_bracket_range, end_bracket_range))
1713                } else {
1714                    None
1715                }
1716            })
1717    }
1718
1719    pub fn diagnostics_update_count(&self) -> usize {
1720        self.diagnostics_update_count
1721    }
1722
1723    pub fn language(&self) -> Option<&Arc<Language>> {
1724        self.excerpts
1725            .iter()
1726            .next()
1727            .and_then(|excerpt| excerpt.buffer.language())
1728    }
1729
1730    pub fn is_dirty(&self) -> bool {
1731        self.is_dirty
1732    }
1733
1734    pub fn has_conflict(&self) -> bool {
1735        self.has_conflict
1736    }
1737
1738    pub fn diagnostic_group<'a, O>(
1739        &'a self,
1740        group_id: usize,
1741    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1742    where
1743        O: text::FromAnchor + 'a,
1744    {
1745        self.as_singleton()
1746            .into_iter()
1747            .flat_map(move |excerpt| excerpt.buffer.diagnostic_group(group_id))
1748    }
1749
1750    pub fn diagnostics_in_range<'a, T, O>(
1751        &'a self,
1752        range: Range<T>,
1753    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1754    where
1755        T: 'a + ToOffset,
1756        O: 'a + text::FromAnchor,
1757    {
1758        self.as_singleton().into_iter().flat_map(move |excerpt| {
1759            excerpt
1760                .buffer
1761                .diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
1762        })
1763    }
1764
1765    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
1766        let range = range.start.to_offset(self)..range.end.to_offset(self);
1767
1768        let mut cursor = self.excerpts.cursor::<usize>();
1769        cursor.seek(&range.start, Bias::Right, &());
1770        let start_excerpt = cursor.item();
1771
1772        cursor.seek(&range.end, Bias::Right, &());
1773        let end_excerpt = cursor.item();
1774
1775        start_excerpt
1776            .zip(end_excerpt)
1777            .and_then(|(start_excerpt, end_excerpt)| {
1778                if start_excerpt.id != end_excerpt.id {
1779                    return None;
1780                }
1781
1782                let excerpt_buffer_start =
1783                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1784                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1785
1786                let start_in_buffer =
1787                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1788                let end_in_buffer =
1789                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1790                let mut ancestor_buffer_range = start_excerpt
1791                    .buffer
1792                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
1793                ancestor_buffer_range.start =
1794                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
1795                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
1796
1797                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
1798                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
1799                Some(start..end)
1800            })
1801    }
1802
1803    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
1804        let excerpt = self.as_singleton()?;
1805        let outline = excerpt.buffer.outline(theme)?;
1806        Some(Outline::new(
1807            outline
1808                .items
1809                .into_iter()
1810                .map(|item| OutlineItem {
1811                    depth: item.depth,
1812                    range: self.anchor_in_excerpt(excerpt.id.clone(), item.range.start)
1813                        ..self.anchor_in_excerpt(excerpt.id.clone(), item.range.end),
1814                    text: item.text,
1815                    highlight_ranges: item.highlight_ranges,
1816                    name_ranges: item.name_ranges,
1817                })
1818                .collect(),
1819        ))
1820    }
1821
1822    fn buffer_snapshot_for_excerpt<'a>(
1823        &'a self,
1824        excerpt_id: &'a ExcerptId,
1825    ) -> Option<(usize, &'a BufferSnapshot)> {
1826        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1827        cursor.seek(&Some(excerpt_id), Bias::Left, &());
1828        if let Some(excerpt) = cursor.item() {
1829            if excerpt.id == *excerpt_id {
1830                return Some((excerpt.buffer_id, &excerpt.buffer));
1831            }
1832        }
1833        None
1834    }
1835
1836    pub fn remote_selections_in_range<'a>(
1837        &'a self,
1838        range: &'a Range<Anchor>,
1839    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
1840        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1841        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
1842        cursor
1843            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
1844            .flat_map(move |excerpt| {
1845                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
1846                if excerpt.id == range.start.excerpt_id {
1847                    query_range.start = range.start.text_anchor.clone();
1848                }
1849                if excerpt.id == range.end.excerpt_id {
1850                    query_range.end = range.end.text_anchor.clone();
1851                }
1852
1853                excerpt
1854                    .buffer
1855                    .remote_selections_in_range(query_range)
1856                    .flat_map(move |(replica_id, selections)| {
1857                        selections.map(move |selection| {
1858                            let mut start = Anchor {
1859                                buffer_id: excerpt.buffer_id,
1860                                excerpt_id: excerpt.id.clone(),
1861                                text_anchor: selection.start.clone(),
1862                            };
1863                            let mut end = Anchor {
1864                                buffer_id: excerpt.buffer_id,
1865                                excerpt_id: excerpt.id.clone(),
1866                                text_anchor: selection.end.clone(),
1867                            };
1868                            if range.start.cmp(&start, self).unwrap().is_gt() {
1869                                start = range.start.clone();
1870                            }
1871                            if range.end.cmp(&end, self).unwrap().is_lt() {
1872                                end = range.end.clone();
1873                            }
1874
1875                            (
1876                                replica_id,
1877                                Selection {
1878                                    id: selection.id,
1879                                    start,
1880                                    end,
1881                                    reversed: selection.reversed,
1882                                    goal: selection.goal,
1883                                },
1884                            )
1885                        })
1886                    })
1887            })
1888    }
1889}
1890
1891impl History {
1892    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
1893        self.transaction_depth += 1;
1894        if self.transaction_depth == 1 {
1895            let id = post_inc(&mut self.next_transaction_id);
1896            self.undo_stack.push(Transaction {
1897                id,
1898                buffer_transactions: Default::default(),
1899                first_edit_at: now,
1900                last_edit_at: now,
1901            });
1902            Some(id)
1903        } else {
1904            None
1905        }
1906    }
1907
1908    fn end_transaction(
1909        &mut self,
1910        now: Instant,
1911        buffer_transactions: HashSet<(usize, TransactionId)>,
1912    ) -> bool {
1913        assert_ne!(self.transaction_depth, 0);
1914        self.transaction_depth -= 1;
1915        if self.transaction_depth == 0 {
1916            if buffer_transactions.is_empty() {
1917                self.undo_stack.pop();
1918                false
1919            } else {
1920                let transaction = self.undo_stack.last_mut().unwrap();
1921                transaction.last_edit_at = now;
1922                transaction.buffer_transactions.extend(buffer_transactions);
1923                true
1924            }
1925        } else {
1926            false
1927        }
1928    }
1929
1930    fn pop_undo(&mut self) -> Option<&Transaction> {
1931        assert_eq!(self.transaction_depth, 0);
1932        if let Some(transaction) = self.undo_stack.pop() {
1933            self.redo_stack.push(transaction);
1934            self.redo_stack.last()
1935        } else {
1936            None
1937        }
1938    }
1939
1940    fn pop_redo(&mut self) -> Option<&Transaction> {
1941        assert_eq!(self.transaction_depth, 0);
1942        if let Some(transaction) = self.redo_stack.pop() {
1943            self.undo_stack.push(transaction);
1944            self.undo_stack.last()
1945        } else {
1946            None
1947        }
1948    }
1949
1950    fn group(&mut self) -> Option<TransactionId> {
1951        let mut new_len = self.undo_stack.len();
1952        let mut transactions = self.undo_stack.iter_mut();
1953
1954        if let Some(mut transaction) = transactions.next_back() {
1955            while let Some(prev_transaction) = transactions.next_back() {
1956                if transaction.first_edit_at - prev_transaction.last_edit_at <= self.group_interval
1957                {
1958                    transaction = prev_transaction;
1959                    new_len -= 1;
1960                } else {
1961                    break;
1962                }
1963            }
1964        }
1965
1966        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
1967        if let Some(last_transaction) = transactions_to_keep.last_mut() {
1968            if let Some(transaction) = transactions_to_merge.last() {
1969                last_transaction.last_edit_at = transaction.last_edit_at;
1970            }
1971        }
1972
1973        self.undo_stack.truncate(new_len);
1974        self.undo_stack.last().map(|t| t.id)
1975    }
1976}
1977
1978impl Excerpt {
1979    fn new(
1980        id: ExcerptId,
1981        buffer_id: usize,
1982        buffer: BufferSnapshot,
1983        range: Range<text::Anchor>,
1984        has_trailing_newline: bool,
1985    ) -> Self {
1986        Excerpt {
1987            id,
1988            max_buffer_row: range.end.to_point(&buffer).row,
1989            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
1990            buffer_id,
1991            buffer,
1992            range,
1993            has_trailing_newline,
1994        }
1995    }
1996
1997    fn chunks_in_range<'a>(
1998        &'a self,
1999        range: Range<usize>,
2000        theme: Option<&'a SyntaxTheme>,
2001    ) -> ExcerptChunks<'a> {
2002        let content_start = self.range.start.to_offset(&self.buffer);
2003        let chunks_start = content_start + range.start;
2004        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2005
2006        let footer_height = if self.has_trailing_newline
2007            && range.start <= self.text_summary.bytes
2008            && range.end > self.text_summary.bytes
2009        {
2010            1
2011        } else {
2012            0
2013        };
2014
2015        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, theme);
2016
2017        ExcerptChunks {
2018            content_chunks,
2019            footer_height,
2020        }
2021    }
2022
2023    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
2024        let content_start = self.range.start.to_offset(&self.buffer);
2025        let bytes_start = content_start + range.start;
2026        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2027        let footer_height = if self.has_trailing_newline
2028            && range.start <= self.text_summary.bytes
2029            && range.end > self.text_summary.bytes
2030        {
2031            1
2032        } else {
2033            0
2034        };
2035        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
2036
2037        ExcerptBytes {
2038            content_bytes,
2039            footer_height,
2040        }
2041    }
2042
2043    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
2044        if text_anchor
2045            .cmp(&self.range.start, &self.buffer)
2046            .unwrap()
2047            .is_lt()
2048        {
2049            self.range.start.clone()
2050        } else if text_anchor
2051            .cmp(&self.range.end, &self.buffer)
2052            .unwrap()
2053            .is_gt()
2054        {
2055            self.range.end.clone()
2056        } else {
2057            text_anchor
2058        }
2059    }
2060
2061    fn contains(&self, anchor: &Anchor) -> bool {
2062        self.buffer_id == anchor.buffer_id
2063            && self
2064                .range
2065                .start
2066                .cmp(&anchor.text_anchor, &self.buffer)
2067                .unwrap()
2068                .is_le()
2069            && self
2070                .range
2071                .end
2072                .cmp(&anchor.text_anchor, &self.buffer)
2073                .unwrap()
2074                .is_ge()
2075    }
2076}
2077
2078impl fmt::Debug for Excerpt {
2079    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2080        f.debug_struct("Excerpt")
2081            .field("id", &self.id)
2082            .field("buffer_id", &self.buffer_id)
2083            .field("range", &self.range)
2084            .field("text_summary", &self.text_summary)
2085            .field("has_trailing_newline", &self.has_trailing_newline)
2086            .finish()
2087    }
2088}
2089
2090impl sum_tree::Item for Excerpt {
2091    type Summary = ExcerptSummary;
2092
2093    fn summary(&self) -> Self::Summary {
2094        let mut text = self.text_summary.clone();
2095        if self.has_trailing_newline {
2096            text += TextSummary::from("\n");
2097        }
2098        ExcerptSummary {
2099            excerpt_id: self.id.clone(),
2100            max_buffer_row: self.max_buffer_row,
2101            text,
2102        }
2103    }
2104}
2105
2106impl sum_tree::Summary for ExcerptSummary {
2107    type Context = ();
2108
2109    fn add_summary(&mut self, summary: &Self, _: &()) {
2110        debug_assert!(summary.excerpt_id > self.excerpt_id);
2111        self.excerpt_id = summary.excerpt_id.clone();
2112        self.text.add_summary(&summary.text, &());
2113        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2114    }
2115}
2116
2117impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2118    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2119        *self += &summary.text;
2120    }
2121}
2122
2123impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2124    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2125        *self += summary.text.bytes;
2126    }
2127}
2128
2129impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2130    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2131        Ord::cmp(self, &cursor_location.text.bytes)
2132    }
2133}
2134
2135impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2136    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2137        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2138    }
2139}
2140
2141impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2142    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2143        *self += summary.text.lines;
2144    }
2145}
2146
2147impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2148    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2149        *self += summary.text.lines_utf16
2150    }
2151}
2152
2153impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2154    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2155        *self = Some(&summary.excerpt_id);
2156    }
2157}
2158
2159impl<'a> MultiBufferRows<'a> {
2160    pub fn seek(&mut self, row: u32) {
2161        self.buffer_row_range = 0..0;
2162
2163        self.excerpts
2164            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2165        if self.excerpts.item().is_none() {
2166            self.excerpts.prev(&());
2167
2168            if self.excerpts.item().is_none() && row == 0 {
2169                self.buffer_row_range = 0..1;
2170                return;
2171            }
2172        }
2173
2174        if let Some(excerpt) = self.excerpts.item() {
2175            let overshoot = row - self.excerpts.start().row;
2176            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2177            self.buffer_row_range.start = excerpt_start + overshoot;
2178            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2179        }
2180    }
2181}
2182
2183impl<'a> Iterator for MultiBufferRows<'a> {
2184    type Item = Option<u32>;
2185
2186    fn next(&mut self) -> Option<Self::Item> {
2187        loop {
2188            if !self.buffer_row_range.is_empty() {
2189                let row = Some(self.buffer_row_range.start);
2190                self.buffer_row_range.start += 1;
2191                return Some(row);
2192            }
2193            self.excerpts.item()?;
2194            self.excerpts.next(&());
2195            let excerpt = self.excerpts.item()?;
2196            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2197            self.buffer_row_range.end =
2198                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2199        }
2200    }
2201}
2202
2203impl<'a> MultiBufferChunks<'a> {
2204    pub fn offset(&self) -> usize {
2205        self.range.start
2206    }
2207
2208    pub fn seek(&mut self, offset: usize) {
2209        self.range.start = offset;
2210        self.excerpts.seek(&offset, Bias::Right, &());
2211        if let Some(excerpt) = self.excerpts.item() {
2212            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2213                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2214                self.theme,
2215            ));
2216        } else {
2217            self.excerpt_chunks = None;
2218        }
2219    }
2220}
2221
2222impl<'a> Iterator for MultiBufferChunks<'a> {
2223    type Item = Chunk<'a>;
2224
2225    fn next(&mut self) -> Option<Self::Item> {
2226        if self.range.is_empty() {
2227            None
2228        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2229            self.range.start += chunk.text.len();
2230            Some(chunk)
2231        } else {
2232            self.excerpts.next(&());
2233            let excerpt = self.excerpts.item()?;
2234            self.excerpt_chunks = Some(
2235                excerpt.chunks_in_range(0..self.range.end - self.excerpts.start(), self.theme),
2236            );
2237            self.next()
2238        }
2239    }
2240}
2241
2242impl<'a> MultiBufferBytes<'a> {
2243    fn consume(&mut self, len: usize) {
2244        self.range.start += len;
2245        self.chunk = &self.chunk[len..];
2246
2247        if !self.range.is_empty() && self.chunk.is_empty() {
2248            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2249                self.chunk = chunk;
2250            } else {
2251                self.excerpts.next(&());
2252                if let Some(excerpt) = self.excerpts.item() {
2253                    let mut excerpt_bytes =
2254                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2255                    self.chunk = excerpt_bytes.next().unwrap();
2256                    self.excerpt_bytes = Some(excerpt_bytes);
2257                }
2258            }
2259        }
2260    }
2261}
2262
2263impl<'a> Iterator for MultiBufferBytes<'a> {
2264    type Item = &'a [u8];
2265
2266    fn next(&mut self) -> Option<Self::Item> {
2267        let chunk = self.chunk;
2268        if chunk.is_empty() {
2269            None
2270        } else {
2271            self.consume(chunk.len());
2272            Some(chunk)
2273        }
2274    }
2275}
2276
2277impl<'a> io::Read for MultiBufferBytes<'a> {
2278    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2279        let len = cmp::min(buf.len(), self.chunk.len());
2280        buf[..len].copy_from_slice(&self.chunk[..len]);
2281        if len > 0 {
2282            self.consume(len);
2283        }
2284        Ok(len)
2285    }
2286}
2287
2288impl<'a> Iterator for ExcerptBytes<'a> {
2289    type Item = &'a [u8];
2290
2291    fn next(&mut self) -> Option<Self::Item> {
2292        if let Some(chunk) = self.content_bytes.next() {
2293            if !chunk.is_empty() {
2294                return Some(chunk);
2295            }
2296        }
2297
2298        if self.footer_height > 0 {
2299            let result = &NEWLINES[..self.footer_height];
2300            self.footer_height = 0;
2301            return Some(result);
2302        }
2303
2304        None
2305    }
2306}
2307
2308impl<'a> Iterator for ExcerptChunks<'a> {
2309    type Item = Chunk<'a>;
2310
2311    fn next(&mut self) -> Option<Self::Item> {
2312        if let Some(chunk) = self.content_chunks.next() {
2313            return Some(chunk);
2314        }
2315
2316        if self.footer_height > 0 {
2317            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2318            self.footer_height = 0;
2319            return Some(Chunk {
2320                text,
2321                ..Default::default()
2322            });
2323        }
2324
2325        None
2326    }
2327}
2328
2329impl ToOffset for Point {
2330    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2331        snapshot.point_to_offset(*self)
2332    }
2333}
2334
2335impl ToOffset for PointUtf16 {
2336    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2337        snapshot.point_utf16_to_offset(*self)
2338    }
2339}
2340
2341impl ToOffset for usize {
2342    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2343        assert!(*self <= snapshot.len(), "offset is out of range");
2344        *self
2345    }
2346}
2347
2348impl ToPoint for usize {
2349    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2350        snapshot.offset_to_point(*self)
2351    }
2352}
2353
2354impl ToPoint for Point {
2355    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2356        *self
2357    }
2358}
2359
2360#[cfg(test)]
2361mod tests {
2362    use super::*;
2363    use gpui::MutableAppContext;
2364    use language::{Buffer, Rope};
2365    use rand::prelude::*;
2366    use std::env;
2367    use text::{Point, RandomCharIter};
2368    use util::test::sample_text;
2369
2370    #[gpui::test]
2371    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2372        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2373        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2374
2375        let snapshot = multibuffer.read(cx).snapshot(cx);
2376        assert_eq!(snapshot.text(), buffer.read(cx).text());
2377
2378        assert_eq!(
2379            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2380            (0..buffer.read(cx).row_count())
2381                .map(Some)
2382                .collect::<Vec<_>>()
2383        );
2384
2385        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2386        let snapshot = multibuffer.read(cx).snapshot(cx);
2387
2388        assert_eq!(snapshot.text(), buffer.read(cx).text());
2389        assert_eq!(
2390            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2391            (0..buffer.read(cx).row_count())
2392                .map(Some)
2393                .collect::<Vec<_>>()
2394        );
2395    }
2396
2397    #[gpui::test]
2398    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2399        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2400        let guest_buffer = cx.add_model(|cx| {
2401            let message = host_buffer.read(cx).to_proto();
2402            Buffer::from_proto(1, message, None, cx).unwrap()
2403        });
2404        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2405        let snapshot = multibuffer.read(cx).snapshot(cx);
2406        assert_eq!(snapshot.text(), "a");
2407
2408        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2409        let snapshot = multibuffer.read(cx).snapshot(cx);
2410        assert_eq!(snapshot.text(), "ab");
2411
2412        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2413        let snapshot = multibuffer.read(cx).snapshot(cx);
2414        assert_eq!(snapshot.text(), "abc");
2415    }
2416
2417    #[gpui::test]
2418    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2419        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2420        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2421        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2422
2423        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2424            let subscription = multibuffer.subscribe();
2425            multibuffer.push_excerpt(
2426                ExcerptProperties {
2427                    buffer: &buffer_1,
2428                    range: Point::new(1, 2)..Point::new(2, 5),
2429                },
2430                cx,
2431            );
2432            assert_eq!(
2433                subscription.consume().into_inner(),
2434                [Edit {
2435                    old: 0..0,
2436                    new: 0..10
2437                }]
2438            );
2439
2440            multibuffer.push_excerpt(
2441                ExcerptProperties {
2442                    buffer: &buffer_1,
2443                    range: Point::new(3, 3)..Point::new(4, 4),
2444                },
2445                cx,
2446            );
2447            multibuffer.push_excerpt(
2448                ExcerptProperties {
2449                    buffer: &buffer_2,
2450                    range: Point::new(3, 1)..Point::new(3, 3),
2451                },
2452                cx,
2453            );
2454            assert_eq!(
2455                subscription.consume().into_inner(),
2456                [Edit {
2457                    old: 10..10,
2458                    new: 10..22
2459                }]
2460            );
2461
2462            subscription
2463        });
2464
2465        let snapshot = multibuffer.read(cx).snapshot(cx);
2466        assert_eq!(
2467            snapshot.text(),
2468            concat!(
2469                "bbbb\n",  // Preserve newlines
2470                "ccccc\n", //
2471                "ddd\n",   //
2472                "eeee\n",  //
2473                "jj"       //
2474            )
2475        );
2476        assert_eq!(
2477            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2478            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2479        );
2480        assert_eq!(
2481            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2482            [Some(3), Some(4), Some(3)]
2483        );
2484        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2485        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2486        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(1, 5)));
2487        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(2, 0)));
2488        assert!(snapshot.range_contains_excerpt_boundary(Point::new(1, 0)..Point::new(4, 0)));
2489        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(2, 0)..Point::new(3, 0)));
2490        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 0)..Point::new(4, 2)));
2491        assert!(!snapshot.range_contains_excerpt_boundary(Point::new(4, 2)..Point::new(4, 2)));
2492
2493        buffer_1.update(cx, |buffer, cx| {
2494            buffer.edit(
2495                [
2496                    Point::new(0, 0)..Point::new(0, 0),
2497                    Point::new(2, 1)..Point::new(2, 3),
2498                ],
2499                "\n",
2500                cx,
2501            );
2502        });
2503
2504        let snapshot = multibuffer.read(cx).snapshot(cx);
2505        assert_eq!(
2506            snapshot.text(),
2507            concat!(
2508                "bbbb\n", // Preserve newlines
2509                "c\n",    //
2510                "cc\n",   //
2511                "ddd\n",  //
2512                "eeee\n", //
2513                "jj"      //
2514            )
2515        );
2516
2517        assert_eq!(
2518            subscription.consume().into_inner(),
2519            [Edit {
2520                old: 6..8,
2521                new: 6..7
2522            }]
2523        );
2524
2525        let snapshot = multibuffer.read(cx).snapshot(cx);
2526        assert_eq!(
2527            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2528            Point::new(0, 4)
2529        );
2530        assert_eq!(
2531            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2532            Point::new(0, 4)
2533        );
2534        assert_eq!(
2535            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2536            Point::new(5, 1)
2537        );
2538        assert_eq!(
2539            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2540            Point::new(5, 2)
2541        );
2542        assert_eq!(
2543            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2544            Point::new(5, 2)
2545        );
2546
2547        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2548            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2549            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2550            multibuffer.snapshot(cx)
2551        });
2552
2553        assert_eq!(
2554            snapshot.text(),
2555            concat!(
2556                "bbbb\n", // Preserve newlines
2557                "c\n",    //
2558                "cc\n",   //
2559                "ddd\n",  //
2560                "eeee",   //
2561            )
2562        );
2563    }
2564
2565    #[gpui::test]
2566    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
2567        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2568
2569        let snapshot = multibuffer.read(cx).snapshot(cx);
2570        assert_eq!(snapshot.text(), "");
2571        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
2572        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
2573    }
2574
2575    #[gpui::test]
2576    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
2577        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2578        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2579        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2580        buffer.update(cx, |buffer, cx| {
2581            buffer.edit([0..0], "X", cx);
2582            buffer.edit([5..5], "Y", cx);
2583        });
2584        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2585
2586        assert_eq!(old_snapshot.text(), "abcd");
2587        assert_eq!(new_snapshot.text(), "XabcdY");
2588
2589        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2590        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2591        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
2592        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
2593    }
2594
2595    #[gpui::test]
2596    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
2597        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2598        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
2599        let multibuffer = cx.add_model(|cx| {
2600            let mut multibuffer = MultiBuffer::new(0);
2601            multibuffer.push_excerpt(
2602                ExcerptProperties {
2603                    buffer: &buffer_1,
2604                    range: 0..4,
2605                },
2606                cx,
2607            );
2608            multibuffer.push_excerpt(
2609                ExcerptProperties {
2610                    buffer: &buffer_2,
2611                    range: 0..5,
2612                },
2613                cx,
2614            );
2615            multibuffer
2616        });
2617        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2618
2619        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
2620        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
2621        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2622        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2623        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2624        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2625
2626        buffer_1.update(cx, |buffer, cx| {
2627            buffer.edit([0..0], "W", cx);
2628            buffer.edit([5..5], "X", cx);
2629        });
2630        buffer_2.update(cx, |buffer, cx| {
2631            buffer.edit([0..0], "Y", cx);
2632            buffer.edit([6..0], "Z", cx);
2633        });
2634        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2635
2636        assert_eq!(old_snapshot.text(), "abcd\nefghi");
2637        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
2638
2639        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2640        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2641        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
2642        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
2643        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
2644        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
2645        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
2646        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
2647        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
2648        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
2649    }
2650
2651    #[gpui::test]
2652    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
2653        cx: &mut MutableAppContext,
2654    ) {
2655        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2656        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
2657        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2658
2659        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
2660        // Add an excerpt from buffer 1 that spans this new insertion.
2661        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
2662        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
2663            multibuffer.push_excerpt(
2664                ExcerptProperties {
2665                    buffer: &buffer_1,
2666                    range: 0..7,
2667                },
2668                cx,
2669            )
2670        });
2671
2672        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
2673        assert_eq!(snapshot_1.text(), "abcd123");
2674
2675        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
2676        let (excerpt_id_2, excerpt_id_3, _) = multibuffer.update(cx, |multibuffer, cx| {
2677            multibuffer.remove_excerpts([&excerpt_id_1], cx);
2678            (
2679                multibuffer.push_excerpt(
2680                    ExcerptProperties {
2681                        buffer: &buffer_2,
2682                        range: 0..4,
2683                    },
2684                    cx,
2685                ),
2686                multibuffer.push_excerpt(
2687                    ExcerptProperties {
2688                        buffer: &buffer_2,
2689                        range: 6..10,
2690                    },
2691                    cx,
2692                ),
2693                multibuffer.push_excerpt(
2694                    ExcerptProperties {
2695                        buffer: &buffer_2,
2696                        range: 12..16,
2697                    },
2698                    cx,
2699                ),
2700            )
2701        });
2702        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
2703        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
2704
2705        // The old excerpt id has been reused.
2706        assert_eq!(excerpt_id_2, excerpt_id_1);
2707
2708        // Resolve some anchors from the previous snapshot in the new snapshot.
2709        // Although there is still an excerpt with the same id, it is for
2710        // a different buffer, so we don't attempt to resolve the old text
2711        // anchor in the new buffer.
2712        assert_eq!(
2713            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
2714            0
2715        );
2716        assert_eq!(
2717            snapshot_2.summaries_for_anchors::<usize, _>(&[
2718                snapshot_1.anchor_before(2),
2719                snapshot_1.anchor_after(3)
2720            ]),
2721            vec![0, 0]
2722        );
2723        let refresh =
2724            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
2725        assert_eq!(
2726            refresh,
2727            &[
2728                (0, snapshot_2.anchor_before(0), false),
2729                (1, snapshot_2.anchor_after(0), false),
2730            ]
2731        );
2732
2733        // Replace the middle excerpt with a smaller excerpt in buffer 2,
2734        // that intersects the old excerpt.
2735        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
2736            multibuffer.remove_excerpts([&excerpt_id_3], cx);
2737            multibuffer.insert_excerpt_after(
2738                &excerpt_id_3,
2739                ExcerptProperties {
2740                    buffer: &buffer_2,
2741                    range: 5..8,
2742                },
2743                cx,
2744            )
2745        });
2746
2747        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
2748        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
2749        assert_ne!(excerpt_id_5, excerpt_id_3);
2750
2751        // Resolve some anchors from the previous snapshot in the new snapshot.
2752        // The anchor in the middle excerpt snaps to the beginning of the
2753        // excerpt, since it is not
2754        let anchors = [
2755            snapshot_2.anchor_before(0),
2756            snapshot_2.anchor_after(2),
2757            snapshot_2.anchor_after(6),
2758            snapshot_2.anchor_after(14),
2759        ];
2760        assert_eq!(
2761            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
2762            &[0, 2, 9, 13]
2763        );
2764
2765        let new_anchors = snapshot_3.refresh_anchors(&anchors);
2766        assert_eq!(
2767            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
2768            &[(0, true), (1, true), (2, true), (3, true)]
2769        );
2770        assert_eq!(
2771            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
2772            &[0, 2, 7, 13]
2773        );
2774    }
2775
2776    #[gpui::test(iterations = 100)]
2777    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
2778        let operations = env::var("OPERATIONS")
2779            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2780            .unwrap_or(10);
2781
2782        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
2783        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2784        let mut excerpt_ids = Vec::new();
2785        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
2786        let mut anchors = Vec::new();
2787        let mut old_versions = Vec::new();
2788
2789        for _ in 0..operations {
2790            match rng.gen_range(0..100) {
2791                0..=19 if !buffers.is_empty() => {
2792                    let buffer = buffers.choose(&mut rng).unwrap();
2793                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
2794                }
2795                20..=29 if !expected_excerpts.is_empty() => {
2796                    let mut ids_to_remove = vec![];
2797                    for _ in 0..rng.gen_range(1..=3) {
2798                        if expected_excerpts.is_empty() {
2799                            break;
2800                        }
2801
2802                        let ix = rng.gen_range(0..expected_excerpts.len());
2803                        ids_to_remove.push(excerpt_ids.remove(ix));
2804                        let (buffer, range) = expected_excerpts.remove(ix);
2805                        let buffer = buffer.read(cx);
2806                        log::info!(
2807                            "Removing excerpt {}: {:?}",
2808                            ix,
2809                            buffer
2810                                .text_for_range(range.to_offset(&buffer))
2811                                .collect::<String>(),
2812                        );
2813                    }
2814                    ids_to_remove.sort_unstable();
2815                    multibuffer.update(cx, |multibuffer, cx| {
2816                        multibuffer.remove_excerpts(&ids_to_remove, cx)
2817                    });
2818                }
2819                30..=39 if !expected_excerpts.is_empty() => {
2820                    let multibuffer = multibuffer.read(cx).read(cx);
2821                    let offset =
2822                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
2823                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
2824                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
2825                    anchors.push(multibuffer.anchor_at(offset, bias));
2826                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
2827                }
2828                40..=44 if !anchors.is_empty() => {
2829                    let multibuffer = multibuffer.read(cx).read(cx);
2830
2831                    anchors = multibuffer
2832                        .refresh_anchors(&anchors)
2833                        .into_iter()
2834                        .map(|a| a.1)
2835                        .collect();
2836
2837                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
2838                    // overshoot its boundaries.
2839                    let mut cursor = multibuffer.excerpts.cursor::<Option<&ExcerptId>>();
2840                    for anchor in &anchors {
2841                        if anchor.excerpt_id == ExcerptId::min()
2842                            || anchor.excerpt_id == ExcerptId::max()
2843                        {
2844                            continue;
2845                        }
2846
2847                        cursor.seek_forward(&Some(&anchor.excerpt_id), Bias::Left, &());
2848                        let excerpt = cursor.item().unwrap();
2849                        assert_eq!(excerpt.id, anchor.excerpt_id);
2850                        assert!(excerpt.contains(anchor));
2851                    }
2852                }
2853                _ => {
2854                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
2855                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
2856                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
2857                        buffers.last().unwrap()
2858                    } else {
2859                        buffers.choose(&mut rng).unwrap()
2860                    };
2861
2862                    let buffer = buffer_handle.read(cx);
2863                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
2864                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
2865                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
2866                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
2867                    let prev_excerpt_id = excerpt_ids
2868                        .get(prev_excerpt_ix)
2869                        .cloned()
2870                        .unwrap_or(ExcerptId::max());
2871                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
2872
2873                    log::info!(
2874                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
2875                        excerpt_ix,
2876                        expected_excerpts.len(),
2877                        buffer_handle.id(),
2878                        buffer.text(),
2879                        start_ix..end_ix,
2880                        &buffer.text()[start_ix..end_ix]
2881                    );
2882
2883                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
2884                        multibuffer.insert_excerpt_after(
2885                            &prev_excerpt_id,
2886                            ExcerptProperties {
2887                                buffer: &buffer_handle,
2888                                range: start_ix..end_ix,
2889                            },
2890                            cx,
2891                        )
2892                    });
2893
2894                    excerpt_ids.insert(excerpt_ix, excerpt_id);
2895                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
2896                }
2897            }
2898
2899            if rng.gen_bool(0.3) {
2900                multibuffer.update(cx, |multibuffer, cx| {
2901                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
2902                })
2903            }
2904
2905            let snapshot = multibuffer.read(cx).snapshot(cx);
2906
2907            let mut excerpt_starts = Vec::new();
2908            let mut expected_text = String::new();
2909            let mut expected_buffer_rows = Vec::new();
2910            for (buffer, range) in &expected_excerpts {
2911                let buffer = buffer.read(cx);
2912                let buffer_range = range.to_offset(buffer);
2913
2914                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
2915                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
2916                expected_text.push('\n');
2917
2918                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
2919                    ..=buffer.offset_to_point(buffer_range.end).row;
2920                for row in buffer_row_range {
2921                    expected_buffer_rows.push(Some(row));
2922                }
2923            }
2924            // Remove final trailing newline.
2925            if !expected_excerpts.is_empty() {
2926                expected_text.pop();
2927            }
2928
2929            // Always report one buffer row
2930            if expected_buffer_rows.is_empty() {
2931                expected_buffer_rows.push(Some(0));
2932            }
2933
2934            assert_eq!(snapshot.text(), expected_text);
2935            log::info!("MultiBuffer text: {:?}", expected_text);
2936
2937            assert_eq!(
2938                snapshot.buffer_rows(0).collect::<Vec<_>>(),
2939                expected_buffer_rows,
2940            );
2941
2942            for _ in 0..5 {
2943                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
2944                assert_eq!(
2945                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
2946                    &expected_buffer_rows[start_row..],
2947                    "buffer_rows({})",
2948                    start_row
2949                );
2950            }
2951
2952            assert_eq!(
2953                snapshot.max_buffer_row(),
2954                expected_buffer_rows
2955                    .into_iter()
2956                    .filter_map(|r| r)
2957                    .max()
2958                    .unwrap()
2959            );
2960
2961            let mut excerpt_starts = excerpt_starts.into_iter();
2962            for (buffer, range) in &expected_excerpts {
2963                let buffer_id = buffer.id();
2964                let buffer = buffer.read(cx);
2965                let buffer_range = range.to_offset(buffer);
2966                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
2967                let buffer_start_point_utf16 =
2968                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
2969
2970                let excerpt_start = excerpt_starts.next().unwrap();
2971                let mut offset = excerpt_start.bytes;
2972                let mut buffer_offset = buffer_range.start;
2973                let mut point = excerpt_start.lines;
2974                let mut buffer_point = buffer_start_point;
2975                let mut point_utf16 = excerpt_start.lines_utf16;
2976                let mut buffer_point_utf16 = buffer_start_point_utf16;
2977                for ch in buffer
2978                    .snapshot()
2979                    .chunks(buffer_range.clone(), None)
2980                    .flat_map(|c| c.text.chars())
2981                {
2982                    for _ in 0..ch.len_utf8() {
2983                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
2984                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
2985                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
2986                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
2987                        assert_eq!(
2988                            left_offset,
2989                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
2990                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
2991                            offset,
2992                            buffer_id,
2993                            buffer_offset,
2994                        );
2995                        assert_eq!(
2996                            right_offset,
2997                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
2998                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
2999                            offset,
3000                            buffer_id,
3001                            buffer_offset,
3002                        );
3003
3004                        let left_point = snapshot.clip_point(point, Bias::Left);
3005                        let right_point = snapshot.clip_point(point, Bias::Right);
3006                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
3007                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
3008                        assert_eq!(
3009                            left_point,
3010                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
3011                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
3012                            point,
3013                            buffer_id,
3014                            buffer_point,
3015                        );
3016                        assert_eq!(
3017                            right_point,
3018                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
3019                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
3020                            point,
3021                            buffer_id,
3022                            buffer_point,
3023                        );
3024
3025                        assert_eq!(
3026                            snapshot.point_to_offset(left_point),
3027                            left_offset,
3028                            "point_to_offset({:?})",
3029                            left_point,
3030                        );
3031                        assert_eq!(
3032                            snapshot.offset_to_point(left_offset),
3033                            left_point,
3034                            "offset_to_point({:?})",
3035                            left_offset,
3036                        );
3037
3038                        offset += 1;
3039                        buffer_offset += 1;
3040                        if ch == '\n' {
3041                            point += Point::new(1, 0);
3042                            buffer_point += Point::new(1, 0);
3043                        } else {
3044                            point += Point::new(0, 1);
3045                            buffer_point += Point::new(0, 1);
3046                        }
3047                    }
3048
3049                    for _ in 0..ch.len_utf16() {
3050                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
3051                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
3052                        let buffer_left_point_utf16 =
3053                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
3054                        let buffer_right_point_utf16 =
3055                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
3056                        assert_eq!(
3057                            left_point_utf16,
3058                            excerpt_start.lines_utf16
3059                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
3060                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
3061                            point_utf16,
3062                            buffer_id,
3063                            buffer_point_utf16,
3064                        );
3065                        assert_eq!(
3066                            right_point_utf16,
3067                            excerpt_start.lines_utf16
3068                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
3069                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
3070                            point_utf16,
3071                            buffer_id,
3072                            buffer_point_utf16,
3073                        );
3074
3075                        if ch == '\n' {
3076                            point_utf16 += PointUtf16::new(1, 0);
3077                            buffer_point_utf16 += PointUtf16::new(1, 0);
3078                        } else {
3079                            point_utf16 += PointUtf16::new(0, 1);
3080                            buffer_point_utf16 += PointUtf16::new(0, 1);
3081                        }
3082                    }
3083                }
3084            }
3085
3086            for (row, line) in expected_text.split('\n').enumerate() {
3087                assert_eq!(
3088                    snapshot.line_len(row as u32),
3089                    line.len() as u32,
3090                    "line_len({}).",
3091                    row
3092                );
3093            }
3094
3095            let text_rope = Rope::from(expected_text.as_str());
3096            for _ in 0..10 {
3097                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3098                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3099
3100                let text_for_range = snapshot
3101                    .text_for_range(start_ix..end_ix)
3102                    .collect::<String>();
3103                assert_eq!(
3104                    text_for_range,
3105                    &expected_text[start_ix..end_ix],
3106                    "incorrect text for range {:?}",
3107                    start_ix..end_ix
3108                );
3109
3110                let excerpted_buffer_ranges =
3111                    multibuffer.read(cx).excerpted_buffers(start_ix..end_ix, cx);
3112                let excerpted_buffers_text = excerpted_buffer_ranges
3113                    .into_iter()
3114                    .map(|(buffer, buffer_range)| {
3115                        buffer
3116                            .read(cx)
3117                            .text_for_range(buffer_range)
3118                            .collect::<String>()
3119                    })
3120                    .collect::<Vec<_>>()
3121                    .join("\n");
3122                assert_eq!(excerpted_buffers_text, text_for_range);
3123
3124                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3125                assert_eq!(
3126                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3127                    expected_summary,
3128                    "incorrect summary for range {:?}",
3129                    start_ix..end_ix
3130                );
3131            }
3132
3133            // Anchor resolution
3134            for (anchor, resolved_offset) in anchors
3135                .iter()
3136                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3137            {
3138                assert!(resolved_offset <= snapshot.len());
3139                assert_eq!(
3140                    snapshot.summary_for_anchor::<usize>(anchor),
3141                    resolved_offset
3142                );
3143            }
3144
3145            for _ in 0..10 {
3146                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3147                assert_eq!(
3148                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3149                    expected_text[..end_ix].chars().rev().collect::<String>(),
3150                );
3151            }
3152
3153            for _ in 0..10 {
3154                let end_ix = rng.gen_range(0..=text_rope.len());
3155                let start_ix = rng.gen_range(0..=end_ix);
3156                assert_eq!(
3157                    snapshot
3158                        .bytes_in_range(start_ix..end_ix)
3159                        .flatten()
3160                        .copied()
3161                        .collect::<Vec<_>>(),
3162                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3163                    "bytes_in_range({:?})",
3164                    start_ix..end_ix,
3165                );
3166            }
3167        }
3168
3169        let snapshot = multibuffer.read(cx).snapshot(cx);
3170        for (old_snapshot, subscription) in old_versions {
3171            let edits = subscription.consume().into_inner();
3172
3173            log::info!(
3174                "applying subscription edits to old text: {:?}: {:?}",
3175                old_snapshot.text(),
3176                edits,
3177            );
3178
3179            let mut text = old_snapshot.text();
3180            for edit in edits {
3181                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3182                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3183            }
3184            assert_eq!(text.to_string(), snapshot.text());
3185        }
3186    }
3187
3188    #[gpui::test]
3189    fn test_history(cx: &mut MutableAppContext) {
3190        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3191        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3192        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3193        let group_interval = multibuffer.read(cx).history.group_interval;
3194        multibuffer.update(cx, |multibuffer, cx| {
3195            multibuffer.push_excerpt(
3196                ExcerptProperties {
3197                    buffer: &buffer_1,
3198                    range: 0..buffer_1.read(cx).len(),
3199                },
3200                cx,
3201            );
3202            multibuffer.push_excerpt(
3203                ExcerptProperties {
3204                    buffer: &buffer_2,
3205                    range: 0..buffer_2.read(cx).len(),
3206                },
3207                cx,
3208            );
3209        });
3210
3211        let mut now = Instant::now();
3212
3213        multibuffer.update(cx, |multibuffer, cx| {
3214            multibuffer.start_transaction_at(now, cx);
3215            multibuffer.edit(
3216                [
3217                    Point::new(0, 0)..Point::new(0, 0),
3218                    Point::new(1, 0)..Point::new(1, 0),
3219                ],
3220                "A",
3221                cx,
3222            );
3223            multibuffer.edit(
3224                [
3225                    Point::new(0, 1)..Point::new(0, 1),
3226                    Point::new(1, 1)..Point::new(1, 1),
3227                ],
3228                "B",
3229                cx,
3230            );
3231            multibuffer.end_transaction_at(now, cx);
3232            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3233
3234            now += 2 * group_interval;
3235            multibuffer.start_transaction_at(now, cx);
3236            multibuffer.edit([2..2], "C", cx);
3237            multibuffer.end_transaction_at(now, cx);
3238            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3239
3240            multibuffer.undo(cx);
3241            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3242
3243            multibuffer.undo(cx);
3244            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3245
3246            multibuffer.redo(cx);
3247            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3248
3249            multibuffer.redo(cx);
3250            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3251
3252            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3253            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3254
3255            multibuffer.undo(cx);
3256            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3257
3258            multibuffer.redo(cx);
3259            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3260
3261            multibuffer.redo(cx);
3262            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3263
3264            multibuffer.undo(cx);
3265            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3266
3267            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3268            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3269
3270            multibuffer.undo(cx);
3271            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3272        });
3273    }
3274}