multi_buffer.rs

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