multi_buffer.rs

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