multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::{Bound, HashMap, HashSet};
   7use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
   8pub use language::Completion;
   9use language::{
  10    Buffer, BufferChunks, BufferSnapshot, Chunk, DiagnosticEntry, Event, File, Language, Outline,
  11    OutlineItem, Selection, ToOffset as _, ToPoint as _, ToPointUtf16 as _, TransactionId,
  12};
  13use std::{
  14    cell::{Ref, RefCell},
  15    cmp, fmt, io,
  16    iter::{self, FromIterator},
  17    ops::{Range, RangeBounds, Sub},
  18    str,
  19    sync::Arc,
  20    time::{Duration, Instant},
  21};
  22use sum_tree::{Bias, Cursor, SumTree};
  23use text::{
  24    locator::Locator,
  25    rope::TextDimension,
  26    subscription::{Subscription, Topic},
  27    AnchorRangeExt as _, Edit, Point, PointUtf16, TextSummary,
  28};
  29use theme::SyntaxTheme;
  30
  31const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  32
  33pub type ExcerptId = Locator;
  34
  35pub struct MultiBuffer {
  36    snapshot: RefCell<MultiBufferSnapshot>,
  37    buffers: RefCell<HashMap<usize, BufferState>>,
  38    subscriptions: Topic,
  39    singleton: bool,
  40    replica_id: ReplicaId,
  41    history: History,
  42}
  43
  44struct History {
  45    next_transaction_id: TransactionId,
  46    undo_stack: Vec<Transaction>,
  47    redo_stack: Vec<Transaction>,
  48    transaction_depth: usize,
  49    group_interval: Duration,
  50}
  51
  52#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug)]
  53pub enum CharKind {
  54    Newline,
  55    Punctuation,
  56    Whitespace,
  57    Word,
  58}
  59
  60struct Transaction {
  61    id: TransactionId,
  62    buffer_transactions: HashSet<(usize, text::TransactionId)>,
  63    first_edit_at: Instant,
  64    last_edit_at: Instant,
  65}
  66
  67pub trait ToOffset: 'static + fmt::Debug {
  68    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  69}
  70
  71pub trait ToPoint: 'static + fmt::Debug {
  72    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  73}
  74
  75pub trait ToPointUtf16: 'static + fmt::Debug {
  76    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
  77}
  78
  79struct BufferState {
  80    buffer: ModelHandle<Buffer>,
  81    last_version: clock::Global,
  82    last_parse_count: usize,
  83    last_selections_update_count: usize,
  84    last_diagnostics_update_count: usize,
  85    last_file_update_count: usize,
  86    excerpts: Vec<ExcerptId>,
  87    _subscriptions: [gpui::Subscription; 2],
  88}
  89
  90#[derive(Clone, Default)]
  91pub struct MultiBufferSnapshot {
  92    singleton: bool,
  93    excerpts: SumTree<Excerpt>,
  94    parse_count: usize,
  95    diagnostics_update_count: usize,
  96    trailing_excerpt_update_count: usize,
  97    is_dirty: bool,
  98    has_conflict: bool,
  99}
 100
 101pub struct ExcerptBoundary {
 102    pub row: u32,
 103    pub buffer: BufferSnapshot,
 104    pub range: Range<text::Anchor>,
 105    pub starts_new_buffer: bool,
 106}
 107
 108#[derive(Clone)]
 109struct Excerpt {
 110    id: ExcerptId,
 111    buffer_id: usize,
 112    buffer: BufferSnapshot,
 113    range: Range<text::Anchor>,
 114    max_buffer_row: u32,
 115    text_summary: TextSummary,
 116    has_trailing_newline: bool,
 117}
 118
 119#[derive(Clone, Debug, Default)]
 120struct ExcerptSummary {
 121    excerpt_id: ExcerptId,
 122    max_buffer_row: u32,
 123    text: TextSummary,
 124}
 125
 126pub struct MultiBufferRows<'a> {
 127    buffer_row_range: Range<u32>,
 128    excerpts: Cursor<'a, Excerpt, Point>,
 129}
 130
 131pub struct MultiBufferChunks<'a> {
 132    range: Range<usize>,
 133    excerpts: Cursor<'a, Excerpt, usize>,
 134    excerpt_chunks: Option<ExcerptChunks<'a>>,
 135    language_aware: bool,
 136}
 137
 138pub struct MultiBufferBytes<'a> {
 139    range: Range<usize>,
 140    excerpts: Cursor<'a, Excerpt, usize>,
 141    excerpt_bytes: Option<ExcerptBytes<'a>>,
 142    chunk: &'a [u8],
 143}
 144
 145struct ExcerptChunks<'a> {
 146    content_chunks: BufferChunks<'a>,
 147    footer_height: usize,
 148}
 149
 150struct ExcerptBytes<'a> {
 151    content_bytes: language::rope::Bytes<'a>,
 152    footer_height: usize,
 153}
 154
 155impl MultiBuffer {
 156    pub fn new(replica_id: ReplicaId) -> Self {
 157        Self {
 158            snapshot: Default::default(),
 159            buffers: Default::default(),
 160            subscriptions: Default::default(),
 161            singleton: false,
 162            replica_id,
 163            history: History {
 164                next_transaction_id: Default::default(),
 165                undo_stack: Default::default(),
 166                redo_stack: Default::default(),
 167                transaction_depth: 0,
 168                group_interval: Duration::from_millis(300),
 169            },
 170        }
 171    }
 172
 173    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 174        let mut this = Self::new(buffer.read(cx).replica_id());
 175        this.singleton = true;
 176        this.push_excerpts(buffer, [text::Anchor::min()..text::Anchor::max()], cx);
 177        this.snapshot.borrow_mut().singleton = true;
 178        this
 179    }
 180
 181    #[cfg(any(test, feature = "test-support"))]
 182    pub fn build_simple(text: &str, cx: &mut gpui::MutableAppContext) -> ModelHandle<Self> {
 183        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
 184        cx.add_model(|cx| Self::singleton(buffer, cx))
 185    }
 186
 187    #[cfg(any(test, feature = "test-support"))]
 188    pub fn build_random(
 189        rng: &mut impl rand::Rng,
 190        cx: &mut gpui::MutableAppContext,
 191    ) -> ModelHandle<Self> {
 192        cx.add_model(|cx| {
 193            let mut multibuffer = MultiBuffer::new(0);
 194            let mutation_count = rng.gen_range(1..=5);
 195            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
 196            multibuffer
 197        })
 198    }
 199
 200    pub fn replica_id(&self) -> ReplicaId {
 201        self.replica_id
 202    }
 203
 204    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 205        self.sync(cx);
 206        self.snapshot.borrow().clone()
 207    }
 208
 209    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 210        self.sync(cx);
 211        self.snapshot.borrow()
 212    }
 213
 214    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 215        if self.singleton {
 216            return Some(
 217                self.buffers
 218                    .borrow()
 219                    .values()
 220                    .next()
 221                    .unwrap()
 222                    .buffer
 223                    .clone(),
 224            );
 225        } else {
 226            None
 227        }
 228    }
 229
 230    pub fn subscribe(&mut self) -> Subscription {
 231        self.subscriptions.subscribe()
 232    }
 233
 234    pub fn edit<I, S, T>(&mut self, ranges: I, new_text: T, cx: &mut ModelContext<Self>)
 235    where
 236        I: IntoIterator<Item = Range<S>>,
 237        S: ToOffset,
 238        T: Into<String>,
 239    {
 240        self.edit_internal(ranges, new_text, false, cx)
 241    }
 242
 243    pub fn edit_with_autoindent<I, S, T>(
 244        &mut self,
 245        ranges: I,
 246        new_text: T,
 247        cx: &mut ModelContext<Self>,
 248    ) where
 249        I: IntoIterator<Item = Range<S>>,
 250        S: ToOffset,
 251        T: Into<String>,
 252    {
 253        self.edit_internal(ranges, new_text, true, cx)
 254    }
 255
 256    pub fn edit_internal<I, S, T>(
 257        &mut self,
 258        ranges_iter: I,
 259        new_text: T,
 260        autoindent: bool,
 261        cx: &mut ModelContext<Self>,
 262    ) where
 263        I: IntoIterator<Item = Range<S>>,
 264        S: ToOffset,
 265        T: Into<String>,
 266    {
 267        if self.buffers.borrow().is_empty() {
 268            return;
 269        }
 270
 271        if let Some(buffer) = self.as_singleton() {
 272            let snapshot = self.read(cx);
 273            let ranges = ranges_iter
 274                .into_iter()
 275                .map(|range| range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot));
 276            return buffer.update(cx, |buffer, cx| {
 277                if autoindent {
 278                    buffer.edit_with_autoindent(ranges, new_text, cx);
 279                } else {
 280                    buffer.edit(ranges, new_text, cx);
 281                }
 282            });
 283        }
 284
 285        let snapshot = self.read(cx);
 286        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, bool)>> = Default::default();
 287        let mut cursor = snapshot.excerpts.cursor::<usize>();
 288        for range in ranges_iter {
 289            let start = range.start.to_offset(&snapshot);
 290            let end = range.end.to_offset(&snapshot);
 291            cursor.seek(&start, Bias::Right, &());
 292            if cursor.item().is_none() && start == *cursor.start() {
 293                cursor.prev(&());
 294            }
 295            let start_excerpt = cursor.item().expect("start offset out of bounds");
 296            let start_overshoot = start - cursor.start();
 297            let buffer_start =
 298                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 299
 300            cursor.seek(&end, Bias::Right, &());
 301            if cursor.item().is_none() && end == *cursor.start() {
 302                cursor.prev(&());
 303            }
 304            let end_excerpt = cursor.item().expect("end offset out of bounds");
 305            let end_overshoot = end - cursor.start();
 306            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 307
 308            if start_excerpt.id == end_excerpt.id {
 309                buffer_edits
 310                    .entry(start_excerpt.buffer_id)
 311                    .or_insert(Vec::new())
 312                    .push((buffer_start..buffer_end, true));
 313            } else {
 314                let start_excerpt_range =
 315                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 316                let end_excerpt_range =
 317                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 318                buffer_edits
 319                    .entry(start_excerpt.buffer_id)
 320                    .or_insert(Vec::new())
 321                    .push((start_excerpt_range, true));
 322                buffer_edits
 323                    .entry(end_excerpt.buffer_id)
 324                    .or_insert(Vec::new())
 325                    .push((end_excerpt_range, false));
 326
 327                cursor.seek(&start, Bias::Right, &());
 328                cursor.next(&());
 329                while let Some(excerpt) = cursor.item() {
 330                    if excerpt.id == end_excerpt.id {
 331                        break;
 332                    }
 333                    buffer_edits
 334                        .entry(excerpt.buffer_id)
 335                        .or_insert(Vec::new())
 336                        .push((excerpt.range.to_offset(&excerpt.buffer), false));
 337                    cursor.next(&());
 338                }
 339            }
 340        }
 341
 342        let new_text = new_text.into();
 343        for (buffer_id, mut edits) in buffer_edits {
 344            edits.sort_unstable_by_key(|(range, _)| range.start);
 345            self.buffers.borrow()[&buffer_id]
 346                .buffer
 347                .update(cx, |buffer, cx| {
 348                    let mut edits = edits.into_iter().peekable();
 349                    let mut insertions = Vec::new();
 350                    let mut deletions = Vec::new();
 351                    while let Some((mut range, mut is_insertion)) = edits.next() {
 352                        while let Some((next_range, next_is_insertion)) = edits.peek() {
 353                            if range.end >= next_range.start {
 354                                range.end = cmp::max(next_range.end, range.end);
 355                                is_insertion |= *next_is_insertion;
 356                                edits.next();
 357                            } else {
 358                                break;
 359                            }
 360                        }
 361
 362                        if is_insertion {
 363                            insertions.push(
 364                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 365                            );
 366                        } else if !range.is_empty() {
 367                            deletions.push(
 368                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 369                            );
 370                        }
 371                    }
 372
 373                    if autoindent {
 374                        buffer.edit_with_autoindent(deletions, "", cx);
 375                        buffer.edit_with_autoindent(insertions, new_text.clone(), cx);
 376                    } else {
 377                        buffer.edit(deletions, "", cx);
 378                        buffer.edit(insertions, new_text.clone(), cx);
 379                    }
 380                })
 381        }
 382    }
 383
 384    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 385        self.start_transaction_at(Instant::now(), cx)
 386    }
 387
 388    pub(crate) fn start_transaction_at(
 389        &mut self,
 390        now: Instant,
 391        cx: &mut ModelContext<Self>,
 392    ) -> Option<TransactionId> {
 393        if let Some(buffer) = self.as_singleton() {
 394            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 395        }
 396
 397        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 398            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 399        }
 400        self.history.start_transaction(now)
 401    }
 402
 403    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 404        self.end_transaction_at(Instant::now(), cx)
 405    }
 406
 407    pub(crate) fn end_transaction_at(
 408        &mut self,
 409        now: Instant,
 410        cx: &mut ModelContext<Self>,
 411    ) -> Option<TransactionId> {
 412        if let Some(buffer) = self.as_singleton() {
 413            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 414        }
 415
 416        let mut buffer_transactions = HashSet::default();
 417        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 418            if let Some(transaction_id) =
 419                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 420            {
 421                buffer_transactions.insert((buffer.id(), transaction_id));
 422            }
 423        }
 424
 425        if self.history.end_transaction(now, buffer_transactions) {
 426            let transaction_id = self.history.group().unwrap();
 427            Some(transaction_id)
 428        } else {
 429            None
 430        }
 431    }
 432
 433    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 434        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 435            buffer.update(cx, |buffer, _| {
 436                buffer.finalize_last_transaction();
 437            });
 438        }
 439    }
 440
 441    pub fn set_active_selections(
 442        &mut self,
 443        selections: &[Selection<Anchor>],
 444        cx: &mut ModelContext<Self>,
 445    ) {
 446        let mut selections_by_buffer: HashMap<usize, Vec<Selection<text::Anchor>>> =
 447            Default::default();
 448        let snapshot = self.read(cx);
 449        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 450        for selection in selections {
 451            cursor.seek(&Some(&selection.start.excerpt_id), Bias::Left, &());
 452            while let Some(excerpt) = cursor.item() {
 453                if excerpt.id > selection.end.excerpt_id {
 454                    break;
 455                }
 456
 457                let mut start = excerpt.range.start.clone();
 458                let mut end = excerpt.range.end.clone();
 459                if excerpt.id == selection.start.excerpt_id {
 460                    start = selection.start.text_anchor.clone();
 461                }
 462                if excerpt.id == selection.end.excerpt_id {
 463                    end = selection.end.text_anchor.clone();
 464                }
 465                selections_by_buffer
 466                    .entry(excerpt.buffer_id)
 467                    .or_default()
 468                    .push(Selection {
 469                        id: selection.id,
 470                        start,
 471                        end,
 472                        reversed: selection.reversed,
 473                        goal: selection.goal,
 474                    });
 475
 476                cursor.next(&());
 477            }
 478        }
 479
 480        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 481            if !selections_by_buffer.contains_key(buffer_id) {
 482                buffer_state
 483                    .buffer
 484                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 485            }
 486        }
 487
 488        for (buffer_id, mut selections) in selections_by_buffer {
 489            self.buffers.borrow()[&buffer_id]
 490                .buffer
 491                .update(cx, |buffer, cx| {
 492                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer).unwrap());
 493                    let mut selections = selections.into_iter().peekable();
 494                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 495                        let mut selection = selections.next()?;
 496                        while let Some(next_selection) = selections.peek() {
 497                            if selection
 498                                .end
 499                                .cmp(&next_selection.start, buffer)
 500                                .unwrap()
 501                                .is_ge()
 502                            {
 503                                let next_selection = selections.next().unwrap();
 504                                if next_selection
 505                                    .end
 506                                    .cmp(&selection.end, buffer)
 507                                    .unwrap()
 508                                    .is_ge()
 509                                {
 510                                    selection.end = next_selection.end;
 511                                }
 512                            } else {
 513                                break;
 514                            }
 515                        }
 516                        Some(selection)
 517                    }));
 518                    buffer.set_active_selections(merged_selections, cx);
 519                });
 520        }
 521    }
 522
 523    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 524        for buffer in self.buffers.borrow().values() {
 525            buffer
 526                .buffer
 527                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 528        }
 529    }
 530
 531    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 532        if let Some(buffer) = self.as_singleton() {
 533            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 534        }
 535
 536        while let Some(transaction) = self.history.pop_undo() {
 537            let mut undone = false;
 538            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 539                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 540                    undone |= buffer.update(cx, |buf, cx| {
 541                        buf.undo_transaction(*buffer_transaction_id, cx)
 542                    });
 543                }
 544            }
 545
 546            if undone {
 547                return Some(transaction.id);
 548            }
 549        }
 550
 551        None
 552    }
 553
 554    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 555        if let Some(buffer) = self.as_singleton() {
 556            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 557        }
 558
 559        while let Some(transaction) = self.history.pop_redo() {
 560            let mut redone = false;
 561            for (buffer_id, buffer_transaction_id) in &transaction.buffer_transactions {
 562                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 563                    redone |= buffer.update(cx, |buf, cx| {
 564                        buf.redo_transaction(*buffer_transaction_id, cx)
 565                    });
 566                }
 567            }
 568
 569            if redone {
 570                return Some(transaction.id);
 571            }
 572        }
 573
 574        None
 575    }
 576
 577    pub fn push_excerpts<O>(
 578        &mut self,
 579        buffer: ModelHandle<Buffer>,
 580        ranges: impl IntoIterator<Item = Range<O>>,
 581        cx: &mut ModelContext<Self>,
 582    ) -> Vec<ExcerptId>
 583    where
 584        O: text::ToOffset,
 585    {
 586        self.insert_excerpts_after(&ExcerptId::max(), buffer, ranges, cx)
 587    }
 588
 589    pub fn push_excerpts_with_context_lines<O>(
 590        &mut self,
 591        buffer: ModelHandle<Buffer>,
 592        ranges: Vec<Range<O>>,
 593        context_line_count: u32,
 594        cx: &mut ModelContext<Self>,
 595    ) -> Vec<Range<Anchor>>
 596    where
 597        O: text::ToPoint + text::ToOffset,
 598    {
 599        let buffer_id = buffer.id();
 600        let buffer_snapshot = buffer.read(cx).snapshot();
 601        let max_point = buffer_snapshot.max_point();
 602
 603        let mut range_counts = Vec::new();
 604        let mut excerpt_ranges = Vec::new();
 605        let mut range_iter = ranges
 606            .iter()
 607            .map(|range| {
 608                range.start.to_point(&buffer_snapshot)..range.end.to_point(&buffer_snapshot)
 609            })
 610            .peekable();
 611        while let Some(range) = range_iter.next() {
 612            let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
 613            let mut excerpt_end =
 614                Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
 615            let mut ranges_in_excerpt = 1;
 616
 617            while let Some(next_range) = range_iter.peek() {
 618                if next_range.start.row <= excerpt_end.row + context_line_count {
 619                    excerpt_end =
 620                        Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
 621                    ranges_in_excerpt += 1;
 622                    range_iter.next();
 623                } else {
 624                    break;
 625                }
 626            }
 627
 628            excerpt_ranges.push(excerpt_start..excerpt_end);
 629            range_counts.push(ranges_in_excerpt);
 630        }
 631
 632        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
 633
 634        let mut anchor_ranges = Vec::new();
 635        let mut ranges = ranges.into_iter();
 636        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
 637            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
 638                let start = Anchor {
 639                    buffer_id,
 640                    excerpt_id: excerpt_id.clone(),
 641                    text_anchor: buffer_snapshot.anchor_after(range.start),
 642                };
 643                let end = Anchor {
 644                    buffer_id,
 645                    excerpt_id: excerpt_id.clone(),
 646                    text_anchor: buffer_snapshot.anchor_after(range.end),
 647                };
 648                start..end
 649            }))
 650        }
 651        anchor_ranges
 652    }
 653
 654    pub fn insert_excerpts_after<O>(
 655        &mut self,
 656        prev_excerpt_id: &ExcerptId,
 657        buffer: ModelHandle<Buffer>,
 658        ranges: impl IntoIterator<Item = Range<O>>,
 659        cx: &mut ModelContext<Self>,
 660    ) -> Vec<ExcerptId>
 661    where
 662        O: text::ToOffset,
 663    {
 664        assert_eq!(self.history.transaction_depth, 0);
 665        self.sync(cx);
 666
 667        let buffer_id = buffer.id();
 668        let buffer_snapshot = buffer.read(cx).snapshot();
 669
 670        let mut buffers = self.buffers.borrow_mut();
 671        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
 672            last_version: buffer_snapshot.version().clone(),
 673            last_parse_count: buffer_snapshot.parse_count(),
 674            last_selections_update_count: buffer_snapshot.selections_update_count(),
 675            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 676            last_file_update_count: buffer_snapshot.file_update_count(),
 677            excerpts: Default::default(),
 678            _subscriptions: [
 679                cx.observe(&buffer, |_, _, cx| cx.notify()),
 680                cx.subscribe(&buffer, Self::on_buffer_event),
 681            ],
 682            buffer,
 683        });
 684
 685        let mut snapshot = self.snapshot.borrow_mut();
 686        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 687        let mut new_excerpts = cursor.slice(&Some(prev_excerpt_id), Bias::Right, &());
 688
 689        let mut prev_id = ExcerptId::min();
 690        let edit_start = new_excerpts.summary().text.bytes;
 691        new_excerpts.update_last(
 692            |excerpt| {
 693                excerpt.has_trailing_newline = true;
 694                prev_id = excerpt.id.clone();
 695            },
 696            &(),
 697        );
 698
 699        let mut next_id = ExcerptId::max();
 700        if let Some(next_excerpt) = cursor.item() {
 701            next_id = next_excerpt.id.clone();
 702        }
 703
 704        let mut ids = Vec::new();
 705        let mut ranges = ranges.into_iter().peekable();
 706        while let Some(range) = ranges.next() {
 707            let id = ExcerptId::between(&prev_id, &next_id);
 708            if let Err(ix) = buffer_state.excerpts.binary_search(&id) {
 709                buffer_state.excerpts.insert(ix, id.clone());
 710            }
 711            let range = buffer_snapshot.anchor_before(&range.start)
 712                ..buffer_snapshot.anchor_after(&range.end);
 713            let excerpt = Excerpt::new(
 714                id.clone(),
 715                buffer_id,
 716                buffer_snapshot.clone(),
 717                range,
 718                ranges.peek().is_some() || cursor.item().is_some(),
 719            );
 720            new_excerpts.push(excerpt, &());
 721            prev_id = id.clone();
 722            ids.push(id);
 723        }
 724
 725        let edit_end = new_excerpts.summary().text.bytes;
 726
 727        let suffix = cursor.suffix(&());
 728        let changed_trailing_excerpt = suffix.is_empty();
 729        new_excerpts.push_tree(suffix, &());
 730        drop(cursor);
 731        snapshot.excerpts = new_excerpts;
 732        if changed_trailing_excerpt {
 733            snapshot.trailing_excerpt_update_count += 1;
 734        }
 735
 736        self.subscriptions.publish_mut([Edit {
 737            old: edit_start..edit_start,
 738            new: edit_start..edit_end,
 739        }]);
 740
 741        cx.notify();
 742        ids
 743    }
 744
 745    pub fn excerpt_ids_for_buffer(&self, buffer: &ModelHandle<Buffer>) -> Vec<ExcerptId> {
 746        self.buffers
 747            .borrow()
 748            .get(&buffer.id())
 749            .map_or(Vec::new(), |state| state.excerpts.clone())
 750    }
 751
 752    pub fn excerpted_buffers<'a, T: ToOffset>(
 753        &'a self,
 754        range: Range<T>,
 755        cx: &AppContext,
 756    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 757        let snapshot = self.snapshot(cx);
 758        let start = range.start.to_offset(&snapshot);
 759        let end = range.end.to_offset(&snapshot);
 760
 761        let mut result = Vec::new();
 762        let mut cursor = snapshot.excerpts.cursor::<usize>();
 763        cursor.seek(&start, Bias::Right, &());
 764        while let Some(excerpt) = cursor.item() {
 765            if *cursor.start() > end {
 766                break;
 767            }
 768
 769            let mut end_before_newline = cursor.end(&());
 770            if excerpt.has_trailing_newline {
 771                end_before_newline -= 1;
 772            }
 773            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 774            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 775            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 776            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 777            result.push((buffer, start..end));
 778            cursor.next(&());
 779        }
 780
 781        result
 782    }
 783
 784    pub fn remove_excerpts<'a>(
 785        &mut self,
 786        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 787        cx: &mut ModelContext<Self>,
 788    ) {
 789        let mut buffers = self.buffers.borrow_mut();
 790        let mut snapshot = self.snapshot.borrow_mut();
 791        let mut new_excerpts = SumTree::new();
 792        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 793        let mut edits = Vec::new();
 794        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 795
 796        while let Some(mut excerpt_id) = excerpt_ids.next() {
 797            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 798            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 799            if let Some(mut excerpt) = cursor.item() {
 800                if excerpt.id != *excerpt_id {
 801                    continue;
 802                }
 803                let mut old_start = cursor.start().1;
 804
 805                // Skip over the removed excerpt.
 806                loop {
 807                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 808                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 809                        if buffer_state.excerpts.is_empty() {
 810                            buffers.remove(&excerpt.buffer_id);
 811                        }
 812                    }
 813                    cursor.next(&());
 814
 815                    // Skip over any subsequent excerpts that are also removed.
 816                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 817                        if let Some(next_excerpt) = cursor.item() {
 818                            if next_excerpt.id == *next_excerpt_id {
 819                                excerpt = next_excerpt;
 820                                excerpt_id = excerpt_ids.next().unwrap();
 821                                continue;
 822                            }
 823                        }
 824                    }
 825
 826                    break;
 827                }
 828
 829                // When removing the last excerpt, remove the trailing newline from
 830                // the previous excerpt.
 831                if cursor.item().is_none() && old_start > 0 {
 832                    old_start -= 1;
 833                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 834                }
 835
 836                // Push an edit for the removal of this run of excerpts.
 837                let old_end = cursor.start().1;
 838                let new_start = new_excerpts.summary().text.bytes;
 839                edits.push(Edit {
 840                    old: old_start..old_end,
 841                    new: new_start..new_start,
 842                });
 843            }
 844        }
 845        let suffix = cursor.suffix(&());
 846        let changed_trailing_excerpt = suffix.is_empty();
 847        new_excerpts.push_tree(suffix, &());
 848        drop(cursor);
 849        snapshot.excerpts = new_excerpts;
 850        if changed_trailing_excerpt {
 851            snapshot.trailing_excerpt_update_count += 1;
 852        }
 853
 854        self.subscriptions.publish_mut(edits);
 855        cx.notify();
 856    }
 857
 858    pub fn text_anchor_for_position<'a, T: ToOffset>(
 859        &'a self,
 860        position: T,
 861        cx: &AppContext,
 862    ) -> (ModelHandle<Buffer>, language::Anchor) {
 863        let snapshot = self.read(cx);
 864        let anchor = snapshot.anchor_before(position);
 865        (
 866            self.buffers.borrow()[&anchor.buffer_id].buffer.clone(),
 867            anchor.text_anchor,
 868        )
 869    }
 870
 871    fn on_buffer_event(
 872        &mut self,
 873        _: ModelHandle<Buffer>,
 874        event: &Event,
 875        cx: &mut ModelContext<Self>,
 876    ) {
 877        cx.emit(event.clone());
 878    }
 879
 880    pub fn format(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 881        let mut format_tasks = Vec::new();
 882        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 883            format_tasks.push(buffer.update(cx, |buffer, cx| buffer.format(cx)));
 884        }
 885
 886        cx.spawn(|_, _| async move {
 887            for format in format_tasks {
 888                format.await?;
 889            }
 890            Ok(())
 891        })
 892    }
 893
 894    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 895        let mut save_tasks = Vec::new();
 896        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 897            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx)));
 898        }
 899
 900        cx.spawn(|_, _| async move {
 901            for save in save_tasks {
 902                save.await?;
 903            }
 904            Ok(())
 905        })
 906    }
 907
 908    pub fn is_completion_trigger<T>(&self, position: T, text: &str, cx: &AppContext) -> bool
 909    where
 910        T: ToOffset,
 911    {
 912        let mut chars = text.chars();
 913        let char = if let Some(char) = chars.next() {
 914            char
 915        } else {
 916            return false;
 917        };
 918        if chars.next().is_some() {
 919            return false;
 920        }
 921
 922        if char.is_alphanumeric() || char == '_' {
 923            return true;
 924        }
 925
 926        let snapshot = self.snapshot(cx);
 927        let anchor = snapshot.anchor_before(position);
 928        let buffer = self.buffers.borrow()[&anchor.buffer_id].buffer.clone();
 929        buffer
 930            .read(cx)
 931            .completion_triggers()
 932            .iter()
 933            .any(|string| string == text)
 934    }
 935
 936    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 937        self.buffers
 938            .borrow()
 939            .values()
 940            .next()
 941            .and_then(|state| state.buffer.read(cx).language())
 942    }
 943
 944    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 945        self.as_singleton()?.read(cx).file()
 946    }
 947
 948    #[cfg(test)]
 949    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 950        self.as_singleton().unwrap().read(cx).is_parsing()
 951    }
 952
 953    fn sync(&self, cx: &AppContext) {
 954        let mut snapshot = self.snapshot.borrow_mut();
 955        let mut excerpts_to_edit = Vec::new();
 956        let mut reparsed = false;
 957        let mut diagnostics_updated = false;
 958        let mut is_dirty = false;
 959        let mut has_conflict = false;
 960        let mut buffers = self.buffers.borrow_mut();
 961        for buffer_state in buffers.values_mut() {
 962            let buffer = buffer_state.buffer.read(cx);
 963            let version = buffer.version();
 964            let parse_count = buffer.parse_count();
 965            let selections_update_count = buffer.selections_update_count();
 966            let diagnostics_update_count = buffer.diagnostics_update_count();
 967            let file_update_count = buffer.file_update_count();
 968
 969            let buffer_edited = version.changed_since(&buffer_state.last_version);
 970            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
 971            let buffer_selections_updated =
 972                selections_update_count > buffer_state.last_selections_update_count;
 973            let buffer_diagnostics_updated =
 974                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
 975            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
 976            if buffer_edited
 977                || buffer_reparsed
 978                || buffer_selections_updated
 979                || buffer_diagnostics_updated
 980                || buffer_file_updated
 981            {
 982                buffer_state.last_version = version;
 983                buffer_state.last_parse_count = parse_count;
 984                buffer_state.last_selections_update_count = selections_update_count;
 985                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
 986                buffer_state.last_file_update_count = file_update_count;
 987                excerpts_to_edit.extend(
 988                    buffer_state
 989                        .excerpts
 990                        .iter()
 991                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
 992                );
 993            }
 994
 995            reparsed |= buffer_reparsed;
 996            diagnostics_updated |= buffer_diagnostics_updated;
 997            is_dirty |= buffer.is_dirty();
 998            has_conflict |= buffer.has_conflict();
 999        }
1000        if reparsed {
1001            snapshot.parse_count += 1;
1002        }
1003        if diagnostics_updated {
1004            snapshot.diagnostics_update_count += 1;
1005        }
1006        snapshot.is_dirty = is_dirty;
1007        snapshot.has_conflict = has_conflict;
1008
1009        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
1010
1011        let mut edits = Vec::new();
1012        let mut new_excerpts = SumTree::new();
1013        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
1014
1015        for (id, buffer, buffer_edited) in excerpts_to_edit {
1016            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
1017            let old_excerpt = cursor.item().unwrap();
1018            let buffer_id = buffer.id();
1019            let buffer = buffer.read(cx);
1020
1021            let mut new_excerpt;
1022            if buffer_edited {
1023                edits.extend(
1024                    buffer
1025                        .edits_since_in_range::<usize>(
1026                            old_excerpt.buffer.version(),
1027                            old_excerpt.range.clone(),
1028                        )
1029                        .map(|mut edit| {
1030                            let excerpt_old_start = cursor.start().1;
1031                            let excerpt_new_start = new_excerpts.summary().text.bytes;
1032                            edit.old.start += excerpt_old_start;
1033                            edit.old.end += excerpt_old_start;
1034                            edit.new.start += excerpt_new_start;
1035                            edit.new.end += excerpt_new_start;
1036                            edit
1037                        }),
1038                );
1039
1040                new_excerpt = Excerpt::new(
1041                    id.clone(),
1042                    buffer_id,
1043                    buffer.snapshot(),
1044                    old_excerpt.range.clone(),
1045                    old_excerpt.has_trailing_newline,
1046                );
1047            } else {
1048                new_excerpt = old_excerpt.clone();
1049                new_excerpt.buffer = buffer.snapshot();
1050            }
1051
1052            new_excerpts.push(new_excerpt, &());
1053            cursor.next(&());
1054        }
1055        new_excerpts.push_tree(cursor.suffix(&()), &());
1056
1057        drop(cursor);
1058        snapshot.excerpts = new_excerpts;
1059
1060        self.subscriptions.publish(edits);
1061    }
1062}
1063
1064#[cfg(any(test, feature = "test-support"))]
1065impl MultiBuffer {
1066    pub fn randomly_edit(
1067        &mut self,
1068        rng: &mut impl rand::Rng,
1069        count: usize,
1070        cx: &mut ModelContext<Self>,
1071    ) {
1072        use text::RandomCharIter;
1073
1074        let snapshot = self.read(cx);
1075        let mut old_ranges: Vec<Range<usize>> = Vec::new();
1076        for _ in 0..count {
1077            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
1078            if last_end > snapshot.len() {
1079                break;
1080            }
1081            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
1082            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1083            old_ranges.push(start_ix..end_ix);
1084        }
1085        let new_text_len = rng.gen_range(0..10);
1086        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1087        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
1088        drop(snapshot);
1089
1090        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
1091    }
1092
1093    pub fn randomly_edit_excerpts(
1094        &mut self,
1095        rng: &mut impl rand::Rng,
1096        mutation_count: usize,
1097        cx: &mut ModelContext<Self>,
1098    ) {
1099        use rand::prelude::*;
1100        use std::env;
1101        use text::RandomCharIter;
1102
1103        let max_excerpts = env::var("MAX_EXCERPTS")
1104            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1105            .unwrap_or(5);
1106
1107        let mut buffers = Vec::new();
1108        for _ in 0..mutation_count {
1109            let excerpt_ids = self
1110                .buffers
1111                .borrow()
1112                .values()
1113                .flat_map(|b| &b.excerpts)
1114                .cloned()
1115                .collect::<Vec<_>>();
1116            if excerpt_ids.len() == 0 || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1117                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1118                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1119                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
1120                    let buffer = buffers.last().unwrap();
1121                    log::info!(
1122                        "Creating new buffer {} with text: {:?}",
1123                        buffer.id(),
1124                        buffer.read(cx).text()
1125                    );
1126                    buffers.last().unwrap().clone()
1127                } else {
1128                    self.buffers
1129                        .borrow()
1130                        .values()
1131                        .choose(rng)
1132                        .unwrap()
1133                        .buffer
1134                        .clone()
1135                };
1136
1137                let buffer = buffer_handle.read(cx);
1138                let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1139                let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1140                log::info!(
1141                    "Inserting excerpt from buffer {} and range {:?}: {:?}",
1142                    buffer_handle.id(),
1143                    start_ix..end_ix,
1144                    &buffer.text()[start_ix..end_ix]
1145                );
1146
1147                let excerpt_id = self.push_excerpts(buffer_handle.clone(), [start_ix..end_ix], cx);
1148                log::info!("Inserted with id: {:?}", excerpt_id);
1149            } else {
1150                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1151                let mut excerpts_to_remove = excerpt_ids
1152                    .choose_multiple(rng, remove_count)
1153                    .cloned()
1154                    .collect::<Vec<_>>();
1155                excerpts_to_remove.sort();
1156                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1157                self.remove_excerpts(&excerpts_to_remove, cx);
1158            }
1159        }
1160    }
1161
1162    pub fn randomly_mutate(
1163        &mut self,
1164        rng: &mut impl rand::Rng,
1165        mutation_count: usize,
1166        cx: &mut ModelContext<Self>,
1167    ) {
1168        if rng.gen_bool(0.7) || self.singleton {
1169            self.randomly_edit(rng, mutation_count, cx);
1170        } else {
1171            self.randomly_edit_excerpts(rng, mutation_count, cx);
1172        }
1173    }
1174}
1175
1176impl Entity for MultiBuffer {
1177    type Event = language::Event;
1178}
1179
1180impl MultiBufferSnapshot {
1181    pub fn text(&self) -> String {
1182        self.chunks(0..self.len(), false)
1183            .map(|chunk| chunk.text)
1184            .collect()
1185    }
1186
1187    pub fn reversed_chars_at<'a, T: ToOffset>(
1188        &'a self,
1189        position: T,
1190    ) -> impl Iterator<Item = char> + 'a {
1191        let mut offset = position.to_offset(self);
1192        let mut cursor = self.excerpts.cursor::<usize>();
1193        cursor.seek(&offset, Bias::Left, &());
1194        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1195            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1196            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1197            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1198            excerpt.buffer.reversed_chunks_in_range(start..end)
1199        });
1200        iter::from_fn(move || {
1201            if offset == *cursor.start() {
1202                cursor.prev(&());
1203                let excerpt = cursor.item()?;
1204                excerpt_chunks = Some(
1205                    excerpt
1206                        .buffer
1207                        .reversed_chunks_in_range(excerpt.range.clone()),
1208                );
1209            }
1210
1211            let excerpt = cursor.item().unwrap();
1212            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1213                offset -= 1;
1214                Some("\n")
1215            } else {
1216                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1217                offset -= chunk.len();
1218                Some(chunk)
1219            }
1220        })
1221        .flat_map(|c| c.chars().rev())
1222    }
1223
1224    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1225        let offset = position.to_offset(self);
1226        self.text_for_range(offset..self.len())
1227            .flat_map(|chunk| chunk.chars())
1228    }
1229
1230    pub fn text_for_range<'a, T: ToOffset>(
1231        &'a self,
1232        range: Range<T>,
1233    ) -> impl Iterator<Item = &'a str> {
1234        self.chunks(range, false).map(|chunk| chunk.text)
1235    }
1236
1237    pub fn is_line_blank(&self, row: u32) -> bool {
1238        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1239            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1240    }
1241
1242    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1243    where
1244        T: ToOffset,
1245    {
1246        let position = position.to_offset(self);
1247        position == self.clip_offset(position, Bias::Left)
1248            && self
1249                .bytes_in_range(position..self.len())
1250                .flatten()
1251                .copied()
1252                .take(needle.len())
1253                .eq(needle.bytes())
1254    }
1255
1256    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
1257        let mut start = start.to_offset(self);
1258        let mut end = start;
1259        let mut next_chars = self.chars_at(start).peekable();
1260        let mut prev_chars = self.reversed_chars_at(start).peekable();
1261        let word_kind = cmp::max(
1262            prev_chars.peek().copied().map(char_kind),
1263            next_chars.peek().copied().map(char_kind),
1264        );
1265
1266        for ch in prev_chars {
1267            if Some(char_kind(ch)) == word_kind {
1268                start -= ch.len_utf8();
1269            } else {
1270                break;
1271            }
1272        }
1273
1274        for ch in next_chars {
1275            if Some(char_kind(ch)) == word_kind {
1276                end += ch.len_utf8();
1277            } else {
1278                break;
1279            }
1280        }
1281
1282        (start..end, word_kind)
1283    }
1284
1285    fn as_singleton(&self) -> Option<&Excerpt> {
1286        if self.singleton {
1287            self.excerpts.iter().next()
1288        } else {
1289            None
1290        }
1291    }
1292
1293    pub fn len(&self) -> usize {
1294        self.excerpts.summary().text.bytes
1295    }
1296
1297    pub fn max_buffer_row(&self) -> u32 {
1298        self.excerpts.summary().max_buffer_row
1299    }
1300
1301    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1302        if let Some(excerpt) = self.as_singleton() {
1303            return excerpt.buffer.clip_offset(offset, bias);
1304        }
1305
1306        let mut cursor = self.excerpts.cursor::<usize>();
1307        cursor.seek(&offset, Bias::Right, &());
1308        let overshoot = if let Some(excerpt) = cursor.item() {
1309            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1310            let buffer_offset = excerpt
1311                .buffer
1312                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1313            buffer_offset.saturating_sub(excerpt_start)
1314        } else {
1315            0
1316        };
1317        cursor.start() + overshoot
1318    }
1319
1320    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1321        if let Some(excerpt) = self.as_singleton() {
1322            return excerpt.buffer.clip_point(point, bias);
1323        }
1324
1325        let mut cursor = self.excerpts.cursor::<Point>();
1326        cursor.seek(&point, Bias::Right, &());
1327        let overshoot = if let Some(excerpt) = cursor.item() {
1328            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1329            let buffer_point = excerpt
1330                .buffer
1331                .clip_point(excerpt_start + (point - cursor.start()), bias);
1332            buffer_point.saturating_sub(excerpt_start)
1333        } else {
1334            Point::zero()
1335        };
1336        *cursor.start() + overshoot
1337    }
1338
1339    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1340        if let Some(excerpt) = self.as_singleton() {
1341            return excerpt.buffer.clip_point_utf16(point, bias);
1342        }
1343
1344        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1345        cursor.seek(&point, Bias::Right, &());
1346        let overshoot = if let Some(excerpt) = cursor.item() {
1347            let excerpt_start = excerpt
1348                .buffer
1349                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1350            let buffer_point = excerpt
1351                .buffer
1352                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1353            buffer_point.saturating_sub(excerpt_start)
1354        } else {
1355            PointUtf16::zero()
1356        };
1357        *cursor.start() + overshoot
1358    }
1359
1360    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1361        let range = range.start.to_offset(self)..range.end.to_offset(self);
1362        let mut excerpts = self.excerpts.cursor::<usize>();
1363        excerpts.seek(&range.start, Bias::Right, &());
1364
1365        let mut chunk = &[][..];
1366        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1367            let mut excerpt_bytes = excerpt
1368                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1369            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1370            Some(excerpt_bytes)
1371        } else {
1372            None
1373        };
1374
1375        MultiBufferBytes {
1376            range,
1377            excerpts,
1378            excerpt_bytes,
1379            chunk,
1380        }
1381    }
1382
1383    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1384        let mut result = MultiBufferRows {
1385            buffer_row_range: 0..0,
1386            excerpts: self.excerpts.cursor(),
1387        };
1388        result.seek(start_row);
1389        result
1390    }
1391
1392    pub fn chunks<'a, T: ToOffset>(
1393        &'a self,
1394        range: Range<T>,
1395        language_aware: bool,
1396    ) -> MultiBufferChunks<'a> {
1397        let range = range.start.to_offset(self)..range.end.to_offset(self);
1398        let mut chunks = MultiBufferChunks {
1399            range: range.clone(),
1400            excerpts: self.excerpts.cursor(),
1401            excerpt_chunks: None,
1402            language_aware,
1403        };
1404        chunks.seek(range.start);
1405        chunks
1406    }
1407
1408    pub fn offset_to_point(&self, offset: usize) -> Point {
1409        if let Some(excerpt) = self.as_singleton() {
1410            return excerpt.buffer.offset_to_point(offset);
1411        }
1412
1413        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1414        cursor.seek(&offset, Bias::Right, &());
1415        if let Some(excerpt) = cursor.item() {
1416            let (start_offset, start_point) = cursor.start();
1417            let overshoot = offset - start_offset;
1418            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1419            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1420            let buffer_point = excerpt
1421                .buffer
1422                .offset_to_point(excerpt_start_offset + overshoot);
1423            *start_point + (buffer_point - excerpt_start_point)
1424        } else {
1425            self.excerpts.summary().text.lines
1426        }
1427    }
1428
1429    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
1430        if let Some(excerpt) = self.as_singleton() {
1431            return excerpt.buffer.offset_to_point_utf16(offset);
1432        }
1433
1434        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
1435        cursor.seek(&offset, Bias::Right, &());
1436        if let Some(excerpt) = cursor.item() {
1437            let (start_offset, start_point) = cursor.start();
1438            let overshoot = offset - start_offset;
1439            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1440            let excerpt_start_point = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1441            let buffer_point = excerpt
1442                .buffer
1443                .offset_to_point_utf16(excerpt_start_offset + overshoot);
1444            *start_point + (buffer_point - excerpt_start_point)
1445        } else {
1446            self.excerpts.summary().text.lines_utf16
1447        }
1448    }
1449
1450    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
1451        if let Some(excerpt) = self.as_singleton() {
1452            return excerpt.buffer.point_to_point_utf16(point);
1453        }
1454
1455        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
1456        cursor.seek(&point, Bias::Right, &());
1457        if let Some(excerpt) = cursor.item() {
1458            let (start_offset, start_point) = cursor.start();
1459            let overshoot = point - start_offset;
1460            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1461            let excerpt_start_point_utf16 = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1462            let buffer_point = excerpt
1463                .buffer
1464                .point_to_point_utf16(excerpt_start_point + overshoot);
1465            *start_point + (buffer_point - excerpt_start_point_utf16)
1466        } else {
1467            self.excerpts.summary().text.lines_utf16
1468        }
1469    }
1470
1471    pub fn point_to_offset(&self, point: Point) -> usize {
1472        if let Some(excerpt) = self.as_singleton() {
1473            return excerpt.buffer.point_to_offset(point);
1474        }
1475
1476        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1477        cursor.seek(&point, Bias::Right, &());
1478        if let Some(excerpt) = cursor.item() {
1479            let (start_point, start_offset) = cursor.start();
1480            let overshoot = point - start_point;
1481            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1482            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1483            let buffer_offset = excerpt
1484                .buffer
1485                .point_to_offset(excerpt_start_point + overshoot);
1486            *start_offset + buffer_offset - excerpt_start_offset
1487        } else {
1488            self.excerpts.summary().text.bytes
1489        }
1490    }
1491
1492    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1493        if let Some(excerpt) = self.as_singleton() {
1494            return excerpt.buffer.point_utf16_to_offset(point);
1495        }
1496
1497        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1498        cursor.seek(&point, Bias::Right, &());
1499        if let Some(excerpt) = cursor.item() {
1500            let (start_point, start_offset) = cursor.start();
1501            let overshoot = point - start_point;
1502            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1503            let excerpt_start_point = excerpt
1504                .buffer
1505                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1506            let buffer_offset = excerpt
1507                .buffer
1508                .point_utf16_to_offset(excerpt_start_point + overshoot);
1509            *start_offset + (buffer_offset - excerpt_start_offset)
1510        } else {
1511            self.excerpts.summary().text.bytes
1512        }
1513    }
1514
1515    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1516        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1517            buffer
1518                .indent_column_for_line(range.start.row)
1519                .min(range.end.column)
1520                .saturating_sub(range.start.column)
1521        } else {
1522            0
1523        }
1524    }
1525
1526    pub fn line_len(&self, row: u32) -> u32 {
1527        if let Some((_, range)) = self.buffer_line_for_row(row) {
1528            range.end.column - range.start.column
1529        } else {
1530            0
1531        }
1532    }
1533
1534    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1535        let mut cursor = self.excerpts.cursor::<Point>();
1536        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1537        if let Some(excerpt) = cursor.item() {
1538            let overshoot = row - cursor.start().row;
1539            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1540            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1541            let buffer_row = excerpt_start.row + overshoot;
1542            let line_start = Point::new(buffer_row, 0);
1543            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1544            return Some((
1545                &excerpt.buffer,
1546                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1547            ));
1548        }
1549        None
1550    }
1551
1552    pub fn max_point(&self) -> Point {
1553        self.text_summary().lines
1554    }
1555
1556    pub fn text_summary(&self) -> TextSummary {
1557        self.excerpts.summary().text
1558    }
1559
1560    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1561    where
1562        D: TextDimension,
1563        O: ToOffset,
1564    {
1565        let mut summary = D::default();
1566        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1567        let mut cursor = self.excerpts.cursor::<usize>();
1568        cursor.seek(&range.start, Bias::Right, &());
1569        if let Some(excerpt) = cursor.item() {
1570            let mut end_before_newline = cursor.end(&());
1571            if excerpt.has_trailing_newline {
1572                end_before_newline -= 1;
1573            }
1574
1575            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1576            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1577            let end_in_excerpt =
1578                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1579            summary.add_assign(
1580                &excerpt
1581                    .buffer
1582                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1583            );
1584
1585            if range.end > end_before_newline {
1586                summary.add_assign(&D::from_text_summary(&TextSummary {
1587                    bytes: 1,
1588                    lines: Point::new(1 as u32, 0),
1589                    lines_utf16: PointUtf16::new(1 as u32, 0),
1590                    first_line_chars: 0,
1591                    last_line_chars: 0,
1592                    longest_row: 0,
1593                    longest_row_chars: 0,
1594                }));
1595            }
1596
1597            cursor.next(&());
1598        }
1599
1600        if range.end > *cursor.start() {
1601            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1602                &range.end,
1603                Bias::Right,
1604                &(),
1605            )));
1606            if let Some(excerpt) = cursor.item() {
1607                range.end = cmp::max(*cursor.start(), range.end);
1608
1609                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1610                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1611                summary.add_assign(
1612                    &excerpt
1613                        .buffer
1614                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1615                );
1616            }
1617        }
1618
1619        summary
1620    }
1621
1622    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1623    where
1624        D: TextDimension + Ord + Sub<D, Output = D>,
1625    {
1626        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1627        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1628        if cursor.item().is_none() {
1629            cursor.next(&());
1630        }
1631
1632        let mut position = D::from_text_summary(&cursor.start().text);
1633        if let Some(excerpt) = cursor.item() {
1634            if excerpt.id == anchor.excerpt_id && excerpt.buffer_id == anchor.buffer_id {
1635                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1636                let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1637                let buffer_position = cmp::min(
1638                    excerpt_buffer_end,
1639                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
1640                );
1641                if buffer_position > excerpt_buffer_start {
1642                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1643                }
1644            }
1645        }
1646        position
1647    }
1648
1649    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1650    where
1651        D: TextDimension + Ord + Sub<D, Output = D>,
1652        I: 'a + IntoIterator<Item = &'a Anchor>,
1653    {
1654        if let Some(excerpt) = self.as_singleton() {
1655            return excerpt
1656                .buffer
1657                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
1658                .collect();
1659        }
1660
1661        let mut anchors = anchors.into_iter().peekable();
1662        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1663        let mut summaries = Vec::new();
1664        while let Some(anchor) = anchors.peek() {
1665            let excerpt_id = &anchor.excerpt_id;
1666            let buffer_id = anchor.buffer_id;
1667            let excerpt_anchors = iter::from_fn(|| {
1668                let anchor = anchors.peek()?;
1669                if anchor.excerpt_id == *excerpt_id && anchor.buffer_id == buffer_id {
1670                    Some(&anchors.next().unwrap().text_anchor)
1671                } else {
1672                    None
1673                }
1674            });
1675
1676            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1677            if cursor.item().is_none() {
1678                cursor.next(&());
1679            }
1680
1681            let position = D::from_text_summary(&cursor.start().text);
1682            if let Some(excerpt) = cursor.item() {
1683                if excerpt.id == *excerpt_id && excerpt.buffer_id == buffer_id {
1684                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1685                    let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1686                    summaries.extend(
1687                        excerpt
1688                            .buffer
1689                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1690                            .map(move |summary| {
1691                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
1692                                let mut position = position.clone();
1693                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1694                                if summary > excerpt_buffer_start {
1695                                    position.add_assign(&(summary - excerpt_buffer_start));
1696                                }
1697                                position
1698                            }),
1699                    );
1700                    continue;
1701                }
1702            }
1703
1704            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1705        }
1706
1707        summaries
1708    }
1709
1710    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1711    where
1712        I: 'a + IntoIterator<Item = &'a Anchor>,
1713    {
1714        let mut anchors = anchors.into_iter().enumerate().peekable();
1715        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1716        let mut result = Vec::new();
1717        while let Some((_, anchor)) = anchors.peek() {
1718            let old_excerpt_id = &anchor.excerpt_id;
1719
1720            // Find the location where this anchor's excerpt should be.
1721            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1722            if cursor.item().is_none() {
1723                cursor.next(&());
1724            }
1725
1726            let next_excerpt = cursor.item();
1727            let prev_excerpt = cursor.prev_item();
1728
1729            // Process all of the anchors for this excerpt.
1730            while let Some((_, anchor)) = anchors.peek() {
1731                if anchor.excerpt_id != *old_excerpt_id {
1732                    break;
1733                }
1734                let mut kept_position = false;
1735                let (anchor_ix, anchor) = anchors.next().unwrap();
1736                let mut anchor = anchor.clone();
1737
1738                // Leave min and max anchors unchanged.
1739                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1740                    kept_position = true;
1741                }
1742                // If the old excerpt still exists at this location, then leave
1743                // the anchor unchanged.
1744                else if next_excerpt.map_or(false, |excerpt| {
1745                    excerpt.id == *old_excerpt_id && excerpt.contains(&anchor)
1746                }) {
1747                    kept_position = true;
1748                }
1749                // If the old excerpt no longer exists at this location, then attempt to
1750                // find an equivalent position for this anchor in an adjacent excerpt.
1751                else {
1752                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1753                        if excerpt.contains(&anchor) {
1754                            anchor.excerpt_id = excerpt.id.clone();
1755                            kept_position = true;
1756                            break;
1757                        }
1758                    }
1759                }
1760                // If there's no adjacent excerpt that contains the anchor's position,
1761                // then report that the anchor has lost its position.
1762                if !kept_position {
1763                    anchor = if let Some(excerpt) = next_excerpt {
1764                        let mut text_anchor = excerpt
1765                            .range
1766                            .start
1767                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1768                        if text_anchor
1769                            .cmp(&excerpt.range.end, &excerpt.buffer)
1770                            .unwrap()
1771                            .is_gt()
1772                        {
1773                            text_anchor = excerpt.range.end.clone();
1774                        }
1775                        Anchor {
1776                            buffer_id: excerpt.buffer_id,
1777                            excerpt_id: excerpt.id.clone(),
1778                            text_anchor,
1779                        }
1780                    } else if let Some(excerpt) = prev_excerpt {
1781                        let mut text_anchor = excerpt
1782                            .range
1783                            .end
1784                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1785                        if text_anchor
1786                            .cmp(&excerpt.range.start, &excerpt.buffer)
1787                            .unwrap()
1788                            .is_lt()
1789                        {
1790                            text_anchor = excerpt.range.start.clone();
1791                        }
1792                        Anchor {
1793                            buffer_id: excerpt.buffer_id,
1794                            excerpt_id: excerpt.id.clone(),
1795                            text_anchor,
1796                        }
1797                    } else if anchor.text_anchor.bias == Bias::Left {
1798                        Anchor::min()
1799                    } else {
1800                        Anchor::max()
1801                    };
1802                }
1803
1804                result.push((anchor_ix, anchor, kept_position));
1805            }
1806        }
1807        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self).unwrap());
1808        result
1809    }
1810
1811    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1812        self.anchor_at(position, Bias::Left)
1813    }
1814
1815    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1816        self.anchor_at(position, Bias::Right)
1817    }
1818
1819    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1820        let offset = position.to_offset(self);
1821        if let Some(excerpt) = self.as_singleton() {
1822            return Anchor {
1823                buffer_id: excerpt.buffer_id,
1824                excerpt_id: excerpt.id.clone(),
1825                text_anchor: excerpt.buffer.anchor_at(offset, bias),
1826            };
1827        }
1828
1829        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1830        cursor.seek(&offset, Bias::Right, &());
1831        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1832            cursor.prev(&());
1833        }
1834        if let Some(excerpt) = cursor.item() {
1835            let mut overshoot = offset.saturating_sub(cursor.start().0);
1836            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1837                overshoot -= 1;
1838                bias = Bias::Right;
1839            }
1840
1841            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1842            let text_anchor =
1843                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1844            Anchor {
1845                buffer_id: excerpt.buffer_id,
1846                excerpt_id: excerpt.id.clone(),
1847                text_anchor,
1848            }
1849        } else if offset == 0 && bias == Bias::Left {
1850            Anchor::min()
1851        } else {
1852            Anchor::max()
1853        }
1854    }
1855
1856    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1857        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1858        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1859        if let Some(excerpt) = cursor.item() {
1860            if excerpt.id == excerpt_id {
1861                let text_anchor = excerpt.clip_anchor(text_anchor);
1862                drop(cursor);
1863                return Anchor {
1864                    buffer_id: excerpt.buffer_id,
1865                    excerpt_id,
1866                    text_anchor,
1867                };
1868            }
1869        }
1870        panic!("excerpt not found");
1871    }
1872
1873    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
1874        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
1875            true
1876        } else if let Some((buffer_id, buffer_snapshot)) =
1877            self.buffer_snapshot_for_excerpt(&anchor.excerpt_id)
1878        {
1879            anchor.buffer_id == buffer_id && buffer_snapshot.can_resolve(&anchor.text_anchor)
1880        } else {
1881            false
1882        }
1883    }
1884
1885    pub fn excerpt_boundaries_in_range<'a, R, T>(
1886        &'a self,
1887        range: R,
1888    ) -> impl Iterator<Item = ExcerptBoundary> + 'a
1889    where
1890        R: RangeBounds<T>,
1891        T: ToOffset,
1892    {
1893        let start_offset;
1894        let start = match range.start_bound() {
1895            Bound::Included(start) => {
1896                start_offset = start.to_offset(self);
1897                Bound::Included(start_offset)
1898            }
1899            Bound::Excluded(start) => {
1900                start_offset = start.to_offset(self);
1901                Bound::Excluded(start_offset)
1902            }
1903            Bound::Unbounded => {
1904                start_offset = 0;
1905                Bound::Unbounded
1906            }
1907        };
1908        let end = match range.end_bound() {
1909            Bound::Included(end) => Bound::Included(end.to_offset(self)),
1910            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
1911            Bound::Unbounded => Bound::Unbounded,
1912        };
1913        let bounds = (start, end);
1914
1915        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1916        cursor.seek(&start_offset, Bias::Right, &());
1917        if cursor.item().is_none() {
1918            cursor.prev(&());
1919        }
1920        if !bounds.contains(&cursor.start().0) {
1921            cursor.next(&());
1922        }
1923
1924        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
1925        std::iter::from_fn(move || {
1926            if self.singleton {
1927                None
1928            } else if bounds.contains(&cursor.start().0) {
1929                let excerpt = cursor.item()?;
1930                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
1931                let boundary = ExcerptBoundary {
1932                    row: cursor.start().1.row,
1933                    buffer: excerpt.buffer.clone(),
1934                    range: excerpt.range.clone(),
1935                    starts_new_buffer,
1936                };
1937
1938                prev_buffer_id = Some(excerpt.buffer_id);
1939                cursor.next(&());
1940                Some(boundary)
1941            } else {
1942                None
1943            }
1944        })
1945    }
1946
1947    pub fn parse_count(&self) -> usize {
1948        self.parse_count
1949    }
1950
1951    pub fn enclosing_bracket_ranges<T: ToOffset>(
1952        &self,
1953        range: Range<T>,
1954    ) -> Option<(Range<usize>, Range<usize>)> {
1955        let range = range.start.to_offset(self)..range.end.to_offset(self);
1956
1957        let mut cursor = self.excerpts.cursor::<usize>();
1958        cursor.seek(&range.start, Bias::Right, &());
1959        let start_excerpt = cursor.item();
1960
1961        cursor.seek(&range.end, Bias::Right, &());
1962        let end_excerpt = cursor.item();
1963
1964        start_excerpt
1965            .zip(end_excerpt)
1966            .and_then(|(start_excerpt, end_excerpt)| {
1967                if start_excerpt.id != end_excerpt.id {
1968                    return None;
1969                }
1970
1971                let excerpt_buffer_start =
1972                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
1973                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
1974
1975                let start_in_buffer =
1976                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
1977                let end_in_buffer =
1978                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
1979                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
1980                    .buffer
1981                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
1982
1983                if start_bracket_range.start >= excerpt_buffer_start
1984                    && end_bracket_range.end < excerpt_buffer_end
1985                {
1986                    start_bracket_range.start =
1987                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
1988                    start_bracket_range.end =
1989                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
1990                    end_bracket_range.start =
1991                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
1992                    end_bracket_range.end =
1993                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
1994                    Some((start_bracket_range, end_bracket_range))
1995                } else {
1996                    None
1997                }
1998            })
1999    }
2000
2001    pub fn diagnostics_update_count(&self) -> usize {
2002        self.diagnostics_update_count
2003    }
2004
2005    pub fn trailing_excerpt_update_count(&self) -> usize {
2006        self.trailing_excerpt_update_count
2007    }
2008
2009    pub fn language(&self) -> Option<&Arc<Language>> {
2010        self.excerpts
2011            .iter()
2012            .next()
2013            .and_then(|excerpt| excerpt.buffer.language())
2014    }
2015
2016    pub fn is_dirty(&self) -> bool {
2017        self.is_dirty
2018    }
2019
2020    pub fn has_conflict(&self) -> bool {
2021        self.has_conflict
2022    }
2023
2024    pub fn diagnostic_group<'a, O>(
2025        &'a self,
2026        group_id: usize,
2027    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2028    where
2029        O: text::FromAnchor + 'a,
2030    {
2031        self.as_singleton()
2032            .into_iter()
2033            .flat_map(move |excerpt| excerpt.buffer.diagnostic_group(group_id))
2034    }
2035
2036    pub fn diagnostics_in_range<'a, T, O>(
2037        &'a self,
2038        range: Range<T>,
2039    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2040    where
2041        T: 'a + ToOffset,
2042        O: 'a + text::FromAnchor,
2043    {
2044        self.as_singleton().into_iter().flat_map(move |excerpt| {
2045            excerpt
2046                .buffer
2047                .diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
2048        })
2049    }
2050
2051    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2052        let range = range.start.to_offset(self)..range.end.to_offset(self);
2053
2054        let mut cursor = self.excerpts.cursor::<usize>();
2055        cursor.seek(&range.start, Bias::Right, &());
2056        let start_excerpt = cursor.item();
2057
2058        cursor.seek(&range.end, Bias::Right, &());
2059        let end_excerpt = cursor.item();
2060
2061        start_excerpt
2062            .zip(end_excerpt)
2063            .and_then(|(start_excerpt, end_excerpt)| {
2064                if start_excerpt.id != end_excerpt.id {
2065                    return None;
2066                }
2067
2068                let excerpt_buffer_start =
2069                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2070                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2071
2072                let start_in_buffer =
2073                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2074                let end_in_buffer =
2075                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2076                let mut ancestor_buffer_range = start_excerpt
2077                    .buffer
2078                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2079                ancestor_buffer_range.start =
2080                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2081                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2082
2083                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
2084                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
2085                Some(start..end)
2086            })
2087    }
2088
2089    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2090        let excerpt = self.as_singleton()?;
2091        let outline = excerpt.buffer.outline(theme)?;
2092        Some(Outline::new(
2093            outline
2094                .items
2095                .into_iter()
2096                .map(|item| OutlineItem {
2097                    depth: item.depth,
2098                    range: self.anchor_in_excerpt(excerpt.id.clone(), item.range.start)
2099                        ..self.anchor_in_excerpt(excerpt.id.clone(), item.range.end),
2100                    text: item.text,
2101                    highlight_ranges: item.highlight_ranges,
2102                    name_ranges: item.name_ranges,
2103                })
2104                .collect(),
2105        ))
2106    }
2107
2108    fn buffer_snapshot_for_excerpt<'a>(
2109        &'a self,
2110        excerpt_id: &'a ExcerptId,
2111    ) -> Option<(usize, &'a BufferSnapshot)> {
2112        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2113        cursor.seek(&Some(excerpt_id), Bias::Left, &());
2114        if let Some(excerpt) = cursor.item() {
2115            if excerpt.id == *excerpt_id {
2116                return Some((excerpt.buffer_id, &excerpt.buffer));
2117            }
2118        }
2119        None
2120    }
2121
2122    pub fn remote_selections_in_range<'a>(
2123        &'a self,
2124        range: &'a Range<Anchor>,
2125    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
2126        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2127        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
2128        cursor
2129            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
2130            .flat_map(move |excerpt| {
2131                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
2132                if excerpt.id == range.start.excerpt_id {
2133                    query_range.start = range.start.text_anchor.clone();
2134                }
2135                if excerpt.id == range.end.excerpt_id {
2136                    query_range.end = range.end.text_anchor.clone();
2137                }
2138
2139                excerpt
2140                    .buffer
2141                    .remote_selections_in_range(query_range)
2142                    .flat_map(move |(replica_id, selections)| {
2143                        selections.map(move |selection| {
2144                            let mut start = Anchor {
2145                                buffer_id: excerpt.buffer_id,
2146                                excerpt_id: excerpt.id.clone(),
2147                                text_anchor: selection.start.clone(),
2148                            };
2149                            let mut end = Anchor {
2150                                buffer_id: excerpt.buffer_id,
2151                                excerpt_id: excerpt.id.clone(),
2152                                text_anchor: selection.end.clone(),
2153                            };
2154                            if range.start.cmp(&start, self).unwrap().is_gt() {
2155                                start = range.start.clone();
2156                            }
2157                            if range.end.cmp(&end, self).unwrap().is_lt() {
2158                                end = range.end.clone();
2159                            }
2160
2161                            (
2162                                replica_id,
2163                                Selection {
2164                                    id: selection.id,
2165                                    start,
2166                                    end,
2167                                    reversed: selection.reversed,
2168                                    goal: selection.goal,
2169                                },
2170                            )
2171                        })
2172                    })
2173            })
2174    }
2175}
2176
2177impl History {
2178    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
2179        self.transaction_depth += 1;
2180        if self.transaction_depth == 1 {
2181            let id = self.next_transaction_id.tick();
2182            self.undo_stack.push(Transaction {
2183                id,
2184                buffer_transactions: Default::default(),
2185                first_edit_at: now,
2186                last_edit_at: now,
2187            });
2188            Some(id)
2189        } else {
2190            None
2191        }
2192    }
2193
2194    fn end_transaction(
2195        &mut self,
2196        now: Instant,
2197        buffer_transactions: HashSet<(usize, TransactionId)>,
2198    ) -> bool {
2199        assert_ne!(self.transaction_depth, 0);
2200        self.transaction_depth -= 1;
2201        if self.transaction_depth == 0 {
2202            if buffer_transactions.is_empty() {
2203                self.undo_stack.pop();
2204                false
2205            } else {
2206                let transaction = self.undo_stack.last_mut().unwrap();
2207                transaction.last_edit_at = now;
2208                transaction.buffer_transactions.extend(buffer_transactions);
2209                true
2210            }
2211        } else {
2212            false
2213        }
2214    }
2215
2216    fn pop_undo(&mut self) -> Option<&Transaction> {
2217        assert_eq!(self.transaction_depth, 0);
2218        if let Some(transaction) = self.undo_stack.pop() {
2219            self.redo_stack.push(transaction);
2220            self.redo_stack.last()
2221        } else {
2222            None
2223        }
2224    }
2225
2226    fn pop_redo(&mut self) -> Option<&Transaction> {
2227        assert_eq!(self.transaction_depth, 0);
2228        if let Some(transaction) = self.redo_stack.pop() {
2229            self.undo_stack.push(transaction);
2230            self.undo_stack.last()
2231        } else {
2232            None
2233        }
2234    }
2235
2236    fn group(&mut self) -> Option<TransactionId> {
2237        let mut new_len = self.undo_stack.len();
2238        let mut transactions = self.undo_stack.iter_mut();
2239
2240        if let Some(mut transaction) = transactions.next_back() {
2241            while let Some(prev_transaction) = transactions.next_back() {
2242                if transaction.first_edit_at - prev_transaction.last_edit_at <= self.group_interval
2243                {
2244                    transaction = prev_transaction;
2245                    new_len -= 1;
2246                } else {
2247                    break;
2248                }
2249            }
2250        }
2251
2252        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
2253        if let Some(last_transaction) = transactions_to_keep.last_mut() {
2254            if let Some(transaction) = transactions_to_merge.last() {
2255                last_transaction.last_edit_at = transaction.last_edit_at;
2256            }
2257        }
2258
2259        self.undo_stack.truncate(new_len);
2260        self.undo_stack.last().map(|t| t.id)
2261    }
2262}
2263
2264impl Excerpt {
2265    fn new(
2266        id: ExcerptId,
2267        buffer_id: usize,
2268        buffer: BufferSnapshot,
2269        range: Range<text::Anchor>,
2270        has_trailing_newline: bool,
2271    ) -> Self {
2272        Excerpt {
2273            id,
2274            max_buffer_row: range.end.to_point(&buffer).row,
2275            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
2276            buffer_id,
2277            buffer,
2278            range,
2279            has_trailing_newline,
2280        }
2281    }
2282
2283    fn chunks_in_range<'a>(
2284        &'a self,
2285        range: Range<usize>,
2286        language_aware: bool,
2287    ) -> ExcerptChunks<'a> {
2288        let content_start = self.range.start.to_offset(&self.buffer);
2289        let chunks_start = content_start + range.start;
2290        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2291
2292        let footer_height = if self.has_trailing_newline
2293            && range.start <= self.text_summary.bytes
2294            && range.end > self.text_summary.bytes
2295        {
2296            1
2297        } else {
2298            0
2299        };
2300
2301        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
2302
2303        ExcerptChunks {
2304            content_chunks,
2305            footer_height,
2306        }
2307    }
2308
2309    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
2310        let content_start = self.range.start.to_offset(&self.buffer);
2311        let bytes_start = content_start + range.start;
2312        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2313        let footer_height = if self.has_trailing_newline
2314            && range.start <= self.text_summary.bytes
2315            && range.end > self.text_summary.bytes
2316        {
2317            1
2318        } else {
2319            0
2320        };
2321        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
2322
2323        ExcerptBytes {
2324            content_bytes,
2325            footer_height,
2326        }
2327    }
2328
2329    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
2330        if text_anchor
2331            .cmp(&self.range.start, &self.buffer)
2332            .unwrap()
2333            .is_lt()
2334        {
2335            self.range.start.clone()
2336        } else if text_anchor
2337            .cmp(&self.range.end, &self.buffer)
2338            .unwrap()
2339            .is_gt()
2340        {
2341            self.range.end.clone()
2342        } else {
2343            text_anchor
2344        }
2345    }
2346
2347    fn contains(&self, anchor: &Anchor) -> bool {
2348        self.buffer_id == anchor.buffer_id
2349            && self
2350                .range
2351                .start
2352                .cmp(&anchor.text_anchor, &self.buffer)
2353                .unwrap()
2354                .is_le()
2355            && self
2356                .range
2357                .end
2358                .cmp(&anchor.text_anchor, &self.buffer)
2359                .unwrap()
2360                .is_ge()
2361    }
2362}
2363
2364impl fmt::Debug for Excerpt {
2365    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2366        f.debug_struct("Excerpt")
2367            .field("id", &self.id)
2368            .field("buffer_id", &self.buffer_id)
2369            .field("range", &self.range)
2370            .field("text_summary", &self.text_summary)
2371            .field("has_trailing_newline", &self.has_trailing_newline)
2372            .finish()
2373    }
2374}
2375
2376impl sum_tree::Item for Excerpt {
2377    type Summary = ExcerptSummary;
2378
2379    fn summary(&self) -> Self::Summary {
2380        let mut text = self.text_summary.clone();
2381        if self.has_trailing_newline {
2382            text += TextSummary::from("\n");
2383        }
2384        ExcerptSummary {
2385            excerpt_id: self.id.clone(),
2386            max_buffer_row: self.max_buffer_row,
2387            text,
2388        }
2389    }
2390}
2391
2392impl sum_tree::Summary for ExcerptSummary {
2393    type Context = ();
2394
2395    fn add_summary(&mut self, summary: &Self, _: &()) {
2396        debug_assert!(summary.excerpt_id > self.excerpt_id);
2397        self.excerpt_id = summary.excerpt_id.clone();
2398        self.text.add_summary(&summary.text, &());
2399        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2400    }
2401}
2402
2403impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2404    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2405        *self += &summary.text;
2406    }
2407}
2408
2409impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2410    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2411        *self += summary.text.bytes;
2412    }
2413}
2414
2415impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2416    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2417        Ord::cmp(self, &cursor_location.text.bytes)
2418    }
2419}
2420
2421impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2422    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2423        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2424    }
2425}
2426
2427impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2428    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2429        *self += summary.text.lines;
2430    }
2431}
2432
2433impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2434    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2435        *self += summary.text.lines_utf16
2436    }
2437}
2438
2439impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2440    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2441        *self = Some(&summary.excerpt_id);
2442    }
2443}
2444
2445impl<'a> MultiBufferRows<'a> {
2446    pub fn seek(&mut self, row: u32) {
2447        self.buffer_row_range = 0..0;
2448
2449        self.excerpts
2450            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2451        if self.excerpts.item().is_none() {
2452            self.excerpts.prev(&());
2453
2454            if self.excerpts.item().is_none() && row == 0 {
2455                self.buffer_row_range = 0..1;
2456                return;
2457            }
2458        }
2459
2460        if let Some(excerpt) = self.excerpts.item() {
2461            let overshoot = row - self.excerpts.start().row;
2462            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2463            self.buffer_row_range.start = excerpt_start + overshoot;
2464            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2465        }
2466    }
2467}
2468
2469impl<'a> Iterator for MultiBufferRows<'a> {
2470    type Item = Option<u32>;
2471
2472    fn next(&mut self) -> Option<Self::Item> {
2473        loop {
2474            if !self.buffer_row_range.is_empty() {
2475                let row = Some(self.buffer_row_range.start);
2476                self.buffer_row_range.start += 1;
2477                return Some(row);
2478            }
2479            self.excerpts.item()?;
2480            self.excerpts.next(&());
2481            let excerpt = self.excerpts.item()?;
2482            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2483            self.buffer_row_range.end =
2484                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2485        }
2486    }
2487}
2488
2489impl<'a> MultiBufferChunks<'a> {
2490    pub fn offset(&self) -> usize {
2491        self.range.start
2492    }
2493
2494    pub fn seek(&mut self, offset: usize) {
2495        self.range.start = offset;
2496        self.excerpts.seek(&offset, Bias::Right, &());
2497        if let Some(excerpt) = self.excerpts.item() {
2498            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2499                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2500                self.language_aware,
2501            ));
2502        } else {
2503            self.excerpt_chunks = None;
2504        }
2505    }
2506}
2507
2508impl<'a> Iterator for MultiBufferChunks<'a> {
2509    type Item = Chunk<'a>;
2510
2511    fn next(&mut self) -> Option<Self::Item> {
2512        if self.range.is_empty() {
2513            None
2514        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2515            self.range.start += chunk.text.len();
2516            Some(chunk)
2517        } else {
2518            self.excerpts.next(&());
2519            let excerpt = self.excerpts.item()?;
2520            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2521                0..self.range.end - self.excerpts.start(),
2522                self.language_aware,
2523            ));
2524            self.next()
2525        }
2526    }
2527}
2528
2529impl<'a> MultiBufferBytes<'a> {
2530    fn consume(&mut self, len: usize) {
2531        self.range.start += len;
2532        self.chunk = &self.chunk[len..];
2533
2534        if !self.range.is_empty() && self.chunk.is_empty() {
2535            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2536                self.chunk = chunk;
2537            } else {
2538                self.excerpts.next(&());
2539                if let Some(excerpt) = self.excerpts.item() {
2540                    let mut excerpt_bytes =
2541                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2542                    self.chunk = excerpt_bytes.next().unwrap();
2543                    self.excerpt_bytes = Some(excerpt_bytes);
2544                }
2545            }
2546        }
2547    }
2548}
2549
2550impl<'a> Iterator for MultiBufferBytes<'a> {
2551    type Item = &'a [u8];
2552
2553    fn next(&mut self) -> Option<Self::Item> {
2554        let chunk = self.chunk;
2555        if chunk.is_empty() {
2556            None
2557        } else {
2558            self.consume(chunk.len());
2559            Some(chunk)
2560        }
2561    }
2562}
2563
2564impl<'a> io::Read for MultiBufferBytes<'a> {
2565    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2566        let len = cmp::min(buf.len(), self.chunk.len());
2567        buf[..len].copy_from_slice(&self.chunk[..len]);
2568        if len > 0 {
2569            self.consume(len);
2570        }
2571        Ok(len)
2572    }
2573}
2574
2575impl<'a> Iterator for ExcerptBytes<'a> {
2576    type Item = &'a [u8];
2577
2578    fn next(&mut self) -> Option<Self::Item> {
2579        if let Some(chunk) = self.content_bytes.next() {
2580            if !chunk.is_empty() {
2581                return Some(chunk);
2582            }
2583        }
2584
2585        if self.footer_height > 0 {
2586            let result = &NEWLINES[..self.footer_height];
2587            self.footer_height = 0;
2588            return Some(result);
2589        }
2590
2591        None
2592    }
2593}
2594
2595impl<'a> Iterator for ExcerptChunks<'a> {
2596    type Item = Chunk<'a>;
2597
2598    fn next(&mut self) -> Option<Self::Item> {
2599        if let Some(chunk) = self.content_chunks.next() {
2600            return Some(chunk);
2601        }
2602
2603        if self.footer_height > 0 {
2604            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2605            self.footer_height = 0;
2606            return Some(Chunk {
2607                text,
2608                ..Default::default()
2609            });
2610        }
2611
2612        None
2613    }
2614}
2615
2616impl ToOffset for Point {
2617    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2618        snapshot.point_to_offset(*self)
2619    }
2620}
2621
2622impl ToOffset for PointUtf16 {
2623    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2624        snapshot.point_utf16_to_offset(*self)
2625    }
2626}
2627
2628impl ToOffset for usize {
2629    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2630        assert!(*self <= snapshot.len(), "offset is out of range");
2631        *self
2632    }
2633}
2634
2635impl ToPoint for usize {
2636    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2637        snapshot.offset_to_point(*self)
2638    }
2639}
2640
2641impl ToPoint for Point {
2642    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2643        *self
2644    }
2645}
2646
2647impl ToPointUtf16 for usize {
2648    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2649        snapshot.offset_to_point_utf16(*self)
2650    }
2651}
2652
2653impl ToPointUtf16 for Point {
2654    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2655        snapshot.point_to_point_utf16(*self)
2656    }
2657}
2658
2659impl ToPointUtf16 for PointUtf16 {
2660    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
2661        *self
2662    }
2663}
2664
2665pub fn char_kind(c: char) -> CharKind {
2666    if c == '\n' {
2667        CharKind::Newline
2668    } else if c.is_whitespace() {
2669        CharKind::Whitespace
2670    } else if c.is_alphanumeric() || c == '_' {
2671        CharKind::Word
2672    } else {
2673        CharKind::Punctuation
2674    }
2675}
2676
2677#[cfg(test)]
2678mod tests {
2679    use super::*;
2680    use gpui::MutableAppContext;
2681    use language::{Buffer, Rope};
2682    use rand::prelude::*;
2683    use std::env;
2684    use text::{Point, RandomCharIter};
2685    use util::test::sample_text;
2686
2687    #[gpui::test]
2688    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2689        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2690        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2691
2692        let snapshot = multibuffer.read(cx).snapshot(cx);
2693        assert_eq!(snapshot.text(), buffer.read(cx).text());
2694
2695        assert_eq!(
2696            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2697            (0..buffer.read(cx).row_count())
2698                .map(Some)
2699                .collect::<Vec<_>>()
2700        );
2701
2702        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2703        let snapshot = multibuffer.read(cx).snapshot(cx);
2704
2705        assert_eq!(snapshot.text(), buffer.read(cx).text());
2706        assert_eq!(
2707            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2708            (0..buffer.read(cx).row_count())
2709                .map(Some)
2710                .collect::<Vec<_>>()
2711        );
2712    }
2713
2714    #[gpui::test]
2715    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2716        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2717        let guest_buffer = cx.add_model(|cx| {
2718            let message = host_buffer.read(cx).to_proto();
2719            Buffer::from_proto(1, message, None, cx).unwrap()
2720        });
2721        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2722        let snapshot = multibuffer.read(cx).snapshot(cx);
2723        assert_eq!(snapshot.text(), "a");
2724
2725        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2726        let snapshot = multibuffer.read(cx).snapshot(cx);
2727        assert_eq!(snapshot.text(), "ab");
2728
2729        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2730        let snapshot = multibuffer.read(cx).snapshot(cx);
2731        assert_eq!(snapshot.text(), "abc");
2732    }
2733
2734    #[gpui::test]
2735    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2736        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2737        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2738        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2739
2740        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2741            let subscription = multibuffer.subscribe();
2742            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(1, 2)..Point::new(2, 5)], cx);
2743            assert_eq!(
2744                subscription.consume().into_inner(),
2745                [Edit {
2746                    old: 0..0,
2747                    new: 0..10
2748                }]
2749            );
2750
2751            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(3, 3)..Point::new(4, 4)], cx);
2752            multibuffer.push_excerpts(buffer_2.clone(), [Point::new(3, 1)..Point::new(3, 3)], cx);
2753            assert_eq!(
2754                subscription.consume().into_inner(),
2755                [Edit {
2756                    old: 10..10,
2757                    new: 10..22
2758                }]
2759            );
2760
2761            subscription
2762        });
2763
2764        let snapshot = multibuffer.read(cx).snapshot(cx);
2765        assert_eq!(
2766            snapshot.text(),
2767            concat!(
2768                "bbbb\n",  // Preserve newlines
2769                "ccccc\n", //
2770                "ddd\n",   //
2771                "eeee\n",  //
2772                "jj"       //
2773            )
2774        );
2775        assert_eq!(
2776            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2777            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2778        );
2779        assert_eq!(
2780            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2781            [Some(3), Some(4), Some(3)]
2782        );
2783        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2784        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2785
2786        assert_eq!(
2787            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
2788            &[
2789                (0, "bbbb\nccccc".to_string(), true),
2790                (2, "ddd\neeee".to_string(), false),
2791                (4, "jj".to_string(), true),
2792            ]
2793        );
2794        assert_eq!(
2795            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
2796            &[(0, "bbbb\nccccc".to_string(), true)]
2797        );
2798        assert_eq!(
2799            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
2800            &[]
2801        );
2802        assert_eq!(
2803            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
2804            &[]
2805        );
2806        assert_eq!(
2807            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2808            &[(2, "ddd\neeee".to_string(), false)]
2809        );
2810        assert_eq!(
2811            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2812            &[(2, "ddd\neeee".to_string(), false)]
2813        );
2814        assert_eq!(
2815            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
2816            &[(2, "ddd\neeee".to_string(), false)]
2817        );
2818        assert_eq!(
2819            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
2820            &[(4, "jj".to_string(), true)]
2821        );
2822        assert_eq!(
2823            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
2824            &[]
2825        );
2826
2827        buffer_1.update(cx, |buffer, cx| {
2828            buffer.edit(
2829                [
2830                    Point::new(0, 0)..Point::new(0, 0),
2831                    Point::new(2, 1)..Point::new(2, 3),
2832                ],
2833                "\n",
2834                cx,
2835            );
2836        });
2837
2838        let snapshot = multibuffer.read(cx).snapshot(cx);
2839        assert_eq!(
2840            snapshot.text(),
2841            concat!(
2842                "bbbb\n", // Preserve newlines
2843                "c\n",    //
2844                "cc\n",   //
2845                "ddd\n",  //
2846                "eeee\n", //
2847                "jj"      //
2848            )
2849        );
2850
2851        assert_eq!(
2852            subscription.consume().into_inner(),
2853            [Edit {
2854                old: 6..8,
2855                new: 6..7
2856            }]
2857        );
2858
2859        let snapshot = multibuffer.read(cx).snapshot(cx);
2860        assert_eq!(
2861            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2862            Point::new(0, 4)
2863        );
2864        assert_eq!(
2865            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2866            Point::new(0, 4)
2867        );
2868        assert_eq!(
2869            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2870            Point::new(5, 1)
2871        );
2872        assert_eq!(
2873            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2874            Point::new(5, 2)
2875        );
2876        assert_eq!(
2877            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2878            Point::new(5, 2)
2879        );
2880
2881        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2882            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2883            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2884            multibuffer.snapshot(cx)
2885        });
2886
2887        assert_eq!(
2888            snapshot.text(),
2889            concat!(
2890                "bbbb\n", // Preserve newlines
2891                "c\n",    //
2892                "cc\n",   //
2893                "ddd\n",  //
2894                "eeee",   //
2895            )
2896        );
2897
2898        fn boundaries_in_range(
2899            range: Range<Point>,
2900            snapshot: &MultiBufferSnapshot,
2901        ) -> Vec<(u32, String, bool)> {
2902            snapshot
2903                .excerpt_boundaries_in_range(range)
2904                .map(|boundary| {
2905                    (
2906                        boundary.row,
2907                        boundary
2908                            .buffer
2909                            .text_for_range(boundary.range)
2910                            .collect::<String>(),
2911                        boundary.starts_new_buffer,
2912                    )
2913                })
2914                .collect::<Vec<_>>()
2915        }
2916    }
2917
2918    #[gpui::test]
2919    fn test_excerpts_with_context_lines(cx: &mut MutableAppContext) {
2920        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
2921
2922        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2923        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
2924            multibuffer.push_excerpts_with_context_lines(
2925                buffer.clone(),
2926                vec![
2927                    Point::new(3, 2)..Point::new(4, 2),
2928                    Point::new(7, 3)..Point::new(7, 1),
2929                    Point::new(15, 0)..Point::new(15, 0),
2930                ],
2931                2,
2932                cx,
2933            )
2934        });
2935
2936        let snapshot = multibuffer.read(cx).snapshot(cx);
2937        assert_eq!(
2938            snapshot.text(),
2939            "bbb\nccc\nddd\neee\nfff\nggg\n\nnnn\nooo\nppp\nqqq\nrrr\n"
2940        );
2941    }
2942
2943    #[gpui::test]
2944    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
2945        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2946
2947        let snapshot = multibuffer.read(cx).snapshot(cx);
2948        assert_eq!(snapshot.text(), "");
2949        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
2950        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
2951    }
2952
2953    #[gpui::test]
2954    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
2955        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2956        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2957        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2958        buffer.update(cx, |buffer, cx| {
2959            buffer.edit([0..0], "X", cx);
2960            buffer.edit([5..5], "Y", cx);
2961        });
2962        let new_snapshot = multibuffer.read(cx).snapshot(cx);
2963
2964        assert_eq!(old_snapshot.text(), "abcd");
2965        assert_eq!(new_snapshot.text(), "XabcdY");
2966
2967        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
2968        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
2969        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
2970        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
2971    }
2972
2973    #[gpui::test]
2974    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
2975        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
2976        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
2977        let multibuffer = cx.add_model(|cx| {
2978            let mut multibuffer = MultiBuffer::new(0);
2979            multibuffer.push_excerpts(buffer_1.clone(), [0..4], cx);
2980            multibuffer.push_excerpts(buffer_2.clone(), [0..5], cx);
2981            multibuffer
2982        });
2983        let old_snapshot = multibuffer.read(cx).snapshot(cx);
2984
2985        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
2986        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
2987        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2988        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
2989        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2990        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
2991
2992        buffer_1.update(cx, |buffer, cx| {
2993            buffer.edit([0..0], "W", cx);
2994            buffer.edit([5..5], "X", cx);
2995        });
2996        buffer_2.update(cx, |buffer, cx| {
2997            buffer.edit([0..0], "Y", cx);
2998            buffer.edit([6..0], "Z", cx);
2999        });
3000        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3001
3002        assert_eq!(old_snapshot.text(), "abcd\nefghi");
3003        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
3004
3005        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3006        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3007        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
3008        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
3009        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
3010        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
3011        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
3012        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
3013        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
3014        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
3015    }
3016
3017    #[gpui::test]
3018    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
3019        cx: &mut MutableAppContext,
3020    ) {
3021        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3022        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
3023        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3024
3025        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
3026        // Add an excerpt from buffer 1 that spans this new insertion.
3027        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
3028        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
3029            multibuffer
3030                .push_excerpts(buffer_1.clone(), [0..7], cx)
3031                .pop()
3032                .unwrap()
3033        });
3034
3035        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
3036        assert_eq!(snapshot_1.text(), "abcd123");
3037
3038        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
3039        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
3040            multibuffer.remove_excerpts([&excerpt_id_1], cx);
3041            let mut ids = multibuffer
3042                .push_excerpts(buffer_2.clone(), [0..4, 6..10, 12..16], cx)
3043                .into_iter();
3044            (ids.next().unwrap(), ids.next().unwrap())
3045        });
3046        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
3047        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
3048
3049        // The old excerpt id has been reused.
3050        assert_eq!(excerpt_id_2, excerpt_id_1);
3051
3052        // Resolve some anchors from the previous snapshot in the new snapshot.
3053        // Although there is still an excerpt with the same id, it is for
3054        // a different buffer, so we don't attempt to resolve the old text
3055        // anchor in the new buffer.
3056        assert_eq!(
3057            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
3058            0
3059        );
3060        assert_eq!(
3061            snapshot_2.summaries_for_anchors::<usize, _>(&[
3062                snapshot_1.anchor_before(2),
3063                snapshot_1.anchor_after(3)
3064            ]),
3065            vec![0, 0]
3066        );
3067        let refresh =
3068            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
3069        assert_eq!(
3070            refresh,
3071            &[
3072                (0, snapshot_2.anchor_before(0), false),
3073                (1, snapshot_2.anchor_after(0), false),
3074            ]
3075        );
3076
3077        // Replace the middle excerpt with a smaller excerpt in buffer 2,
3078        // that intersects the old excerpt.
3079        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
3080            multibuffer.remove_excerpts([&excerpt_id_3], cx);
3081            multibuffer
3082                .insert_excerpts_after(&excerpt_id_3, buffer_2.clone(), [5..8], cx)
3083                .pop()
3084                .unwrap()
3085        });
3086
3087        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
3088        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
3089        assert_ne!(excerpt_id_5, excerpt_id_3);
3090
3091        // Resolve some anchors from the previous snapshot in the new snapshot.
3092        // The anchor in the middle excerpt snaps to the beginning of the
3093        // excerpt, since it is not
3094        let anchors = [
3095            snapshot_2.anchor_before(0),
3096            snapshot_2.anchor_after(2),
3097            snapshot_2.anchor_after(6),
3098            snapshot_2.anchor_after(14),
3099        ];
3100        assert_eq!(
3101            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
3102            &[0, 2, 9, 13]
3103        );
3104
3105        let new_anchors = snapshot_3.refresh_anchors(&anchors);
3106        assert_eq!(
3107            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
3108            &[(0, true), (1, true), (2, true), (3, true)]
3109        );
3110        assert_eq!(
3111            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
3112            &[0, 2, 7, 13]
3113        );
3114    }
3115
3116    #[gpui::test(iterations = 100)]
3117    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
3118        let operations = env::var("OPERATIONS")
3119            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
3120            .unwrap_or(10);
3121
3122        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
3123        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3124        let mut excerpt_ids = Vec::new();
3125        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
3126        let mut anchors = Vec::new();
3127        let mut old_versions = Vec::new();
3128
3129        for _ in 0..operations {
3130            match rng.gen_range(0..100) {
3131                0..=19 if !buffers.is_empty() => {
3132                    let buffer = buffers.choose(&mut rng).unwrap();
3133                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
3134                }
3135                20..=29 if !expected_excerpts.is_empty() => {
3136                    let mut ids_to_remove = vec![];
3137                    for _ in 0..rng.gen_range(1..=3) {
3138                        if expected_excerpts.is_empty() {
3139                            break;
3140                        }
3141
3142                        let ix = rng.gen_range(0..expected_excerpts.len());
3143                        ids_to_remove.push(excerpt_ids.remove(ix));
3144                        let (buffer, range) = expected_excerpts.remove(ix);
3145                        let buffer = buffer.read(cx);
3146                        log::info!(
3147                            "Removing excerpt {}: {:?}",
3148                            ix,
3149                            buffer
3150                                .text_for_range(range.to_offset(&buffer))
3151                                .collect::<String>(),
3152                        );
3153                    }
3154                    ids_to_remove.sort_unstable();
3155                    multibuffer.update(cx, |multibuffer, cx| {
3156                        multibuffer.remove_excerpts(&ids_to_remove, cx)
3157                    });
3158                }
3159                30..=39 if !expected_excerpts.is_empty() => {
3160                    let multibuffer = multibuffer.read(cx).read(cx);
3161                    let offset =
3162                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
3163                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
3164                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
3165                    anchors.push(multibuffer.anchor_at(offset, bias));
3166                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
3167                }
3168                40..=44 if !anchors.is_empty() => {
3169                    let multibuffer = multibuffer.read(cx).read(cx);
3170
3171                    anchors = multibuffer
3172                        .refresh_anchors(&anchors)
3173                        .into_iter()
3174                        .map(|a| a.1)
3175                        .collect();
3176
3177                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
3178                    // overshoot its boundaries.
3179                    let mut cursor = multibuffer.excerpts.cursor::<Option<&ExcerptId>>();
3180                    for anchor in &anchors {
3181                        if anchor.excerpt_id == ExcerptId::min()
3182                            || anchor.excerpt_id == ExcerptId::max()
3183                        {
3184                            continue;
3185                        }
3186
3187                        cursor.seek_forward(&Some(&anchor.excerpt_id), Bias::Left, &());
3188                        let excerpt = cursor.item().unwrap();
3189                        assert_eq!(excerpt.id, anchor.excerpt_id);
3190                        assert!(excerpt.contains(anchor));
3191                    }
3192                }
3193                _ => {
3194                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
3195                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
3196                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
3197                        buffers.last().unwrap()
3198                    } else {
3199                        buffers.choose(&mut rng).unwrap()
3200                    };
3201
3202                    let buffer = buffer_handle.read(cx);
3203                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3204                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3205                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3206                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
3207                    let prev_excerpt_id = excerpt_ids
3208                        .get(prev_excerpt_ix)
3209                        .cloned()
3210                        .unwrap_or(ExcerptId::max());
3211                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
3212
3213                    log::info!(
3214                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
3215                        excerpt_ix,
3216                        expected_excerpts.len(),
3217                        buffer_handle.id(),
3218                        buffer.text(),
3219                        start_ix..end_ix,
3220                        &buffer.text()[start_ix..end_ix]
3221                    );
3222
3223                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3224                        multibuffer
3225                            .insert_excerpts_after(
3226                                &prev_excerpt_id,
3227                                buffer_handle.clone(),
3228                                [start_ix..end_ix],
3229                                cx,
3230                            )
3231                            .pop()
3232                            .unwrap()
3233                    });
3234
3235                    excerpt_ids.insert(excerpt_ix, excerpt_id);
3236                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
3237                }
3238            }
3239
3240            if rng.gen_bool(0.3) {
3241                multibuffer.update(cx, |multibuffer, cx| {
3242                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
3243                })
3244            }
3245
3246            let snapshot = multibuffer.read(cx).snapshot(cx);
3247
3248            let mut excerpt_starts = Vec::new();
3249            let mut expected_text = String::new();
3250            let mut expected_buffer_rows = Vec::new();
3251            for (buffer, range) in &expected_excerpts {
3252                let buffer = buffer.read(cx);
3253                let buffer_range = range.to_offset(buffer);
3254
3255                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
3256                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
3257                expected_text.push('\n');
3258
3259                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
3260                    ..=buffer.offset_to_point(buffer_range.end).row;
3261                for row in buffer_row_range {
3262                    expected_buffer_rows.push(Some(row));
3263                }
3264            }
3265            // Remove final trailing newline.
3266            if !expected_excerpts.is_empty() {
3267                expected_text.pop();
3268            }
3269
3270            // Always report one buffer row
3271            if expected_buffer_rows.is_empty() {
3272                expected_buffer_rows.push(Some(0));
3273            }
3274
3275            assert_eq!(snapshot.text(), expected_text);
3276            log::info!("MultiBuffer text: {:?}", expected_text);
3277
3278            assert_eq!(
3279                snapshot.buffer_rows(0).collect::<Vec<_>>(),
3280                expected_buffer_rows,
3281            );
3282
3283            for _ in 0..5 {
3284                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
3285                assert_eq!(
3286                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
3287                    &expected_buffer_rows[start_row..],
3288                    "buffer_rows({})",
3289                    start_row
3290                );
3291            }
3292
3293            assert_eq!(
3294                snapshot.max_buffer_row(),
3295                expected_buffer_rows
3296                    .into_iter()
3297                    .filter_map(|r| r)
3298                    .max()
3299                    .unwrap()
3300            );
3301
3302            let mut excerpt_starts = excerpt_starts.into_iter();
3303            for (buffer, range) in &expected_excerpts {
3304                let buffer_id = buffer.id();
3305                let buffer = buffer.read(cx);
3306                let buffer_range = range.to_offset(buffer);
3307                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
3308                let buffer_start_point_utf16 =
3309                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
3310
3311                let excerpt_start = excerpt_starts.next().unwrap();
3312                let mut offset = excerpt_start.bytes;
3313                let mut buffer_offset = buffer_range.start;
3314                let mut point = excerpt_start.lines;
3315                let mut buffer_point = buffer_start_point;
3316                let mut point_utf16 = excerpt_start.lines_utf16;
3317                let mut buffer_point_utf16 = buffer_start_point_utf16;
3318                for ch in buffer
3319                    .snapshot()
3320                    .chunks(buffer_range.clone(), false)
3321                    .flat_map(|c| c.text.chars())
3322                {
3323                    for _ in 0..ch.len_utf8() {
3324                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
3325                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
3326                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
3327                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
3328                        assert_eq!(
3329                            left_offset,
3330                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
3331                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
3332                            offset,
3333                            buffer_id,
3334                            buffer_offset,
3335                        );
3336                        assert_eq!(
3337                            right_offset,
3338                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
3339                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
3340                            offset,
3341                            buffer_id,
3342                            buffer_offset,
3343                        );
3344
3345                        let left_point = snapshot.clip_point(point, Bias::Left);
3346                        let right_point = snapshot.clip_point(point, Bias::Right);
3347                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
3348                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
3349                        assert_eq!(
3350                            left_point,
3351                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
3352                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
3353                            point,
3354                            buffer_id,
3355                            buffer_point,
3356                        );
3357                        assert_eq!(
3358                            right_point,
3359                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
3360                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
3361                            point,
3362                            buffer_id,
3363                            buffer_point,
3364                        );
3365
3366                        assert_eq!(
3367                            snapshot.point_to_offset(left_point),
3368                            left_offset,
3369                            "point_to_offset({:?})",
3370                            left_point,
3371                        );
3372                        assert_eq!(
3373                            snapshot.offset_to_point(left_offset),
3374                            left_point,
3375                            "offset_to_point({:?})",
3376                            left_offset,
3377                        );
3378
3379                        offset += 1;
3380                        buffer_offset += 1;
3381                        if ch == '\n' {
3382                            point += Point::new(1, 0);
3383                            buffer_point += Point::new(1, 0);
3384                        } else {
3385                            point += Point::new(0, 1);
3386                            buffer_point += Point::new(0, 1);
3387                        }
3388                    }
3389
3390                    for _ in 0..ch.len_utf16() {
3391                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
3392                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
3393                        let buffer_left_point_utf16 =
3394                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
3395                        let buffer_right_point_utf16 =
3396                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
3397                        assert_eq!(
3398                            left_point_utf16,
3399                            excerpt_start.lines_utf16
3400                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
3401                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
3402                            point_utf16,
3403                            buffer_id,
3404                            buffer_point_utf16,
3405                        );
3406                        assert_eq!(
3407                            right_point_utf16,
3408                            excerpt_start.lines_utf16
3409                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
3410                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
3411                            point_utf16,
3412                            buffer_id,
3413                            buffer_point_utf16,
3414                        );
3415
3416                        if ch == '\n' {
3417                            point_utf16 += PointUtf16::new(1, 0);
3418                            buffer_point_utf16 += PointUtf16::new(1, 0);
3419                        } else {
3420                            point_utf16 += PointUtf16::new(0, 1);
3421                            buffer_point_utf16 += PointUtf16::new(0, 1);
3422                        }
3423                    }
3424                }
3425            }
3426
3427            for (row, line) in expected_text.split('\n').enumerate() {
3428                assert_eq!(
3429                    snapshot.line_len(row as u32),
3430                    line.len() as u32,
3431                    "line_len({}).",
3432                    row
3433                );
3434            }
3435
3436            let text_rope = Rope::from(expected_text.as_str());
3437            for _ in 0..10 {
3438                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3439                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3440
3441                let text_for_range = snapshot
3442                    .text_for_range(start_ix..end_ix)
3443                    .collect::<String>();
3444                assert_eq!(
3445                    text_for_range,
3446                    &expected_text[start_ix..end_ix],
3447                    "incorrect text for range {:?}",
3448                    start_ix..end_ix
3449                );
3450
3451                let excerpted_buffer_ranges =
3452                    multibuffer.read(cx).excerpted_buffers(start_ix..end_ix, cx);
3453                let excerpted_buffers_text = excerpted_buffer_ranges
3454                    .into_iter()
3455                    .map(|(buffer, buffer_range)| {
3456                        buffer
3457                            .read(cx)
3458                            .text_for_range(buffer_range)
3459                            .collect::<String>()
3460                    })
3461                    .collect::<Vec<_>>()
3462                    .join("\n");
3463                assert_eq!(excerpted_buffers_text, text_for_range);
3464
3465                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3466                assert_eq!(
3467                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3468                    expected_summary,
3469                    "incorrect summary for range {:?}",
3470                    start_ix..end_ix
3471                );
3472            }
3473
3474            // Anchor resolution
3475            for (anchor, resolved_offset) in anchors
3476                .iter()
3477                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3478            {
3479                assert!(resolved_offset <= snapshot.len());
3480                assert_eq!(
3481                    snapshot.summary_for_anchor::<usize>(anchor),
3482                    resolved_offset
3483                );
3484            }
3485
3486            for _ in 0..10 {
3487                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3488                assert_eq!(
3489                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3490                    expected_text[..end_ix].chars().rev().collect::<String>(),
3491                );
3492            }
3493
3494            for _ in 0..10 {
3495                let end_ix = rng.gen_range(0..=text_rope.len());
3496                let start_ix = rng.gen_range(0..=end_ix);
3497                assert_eq!(
3498                    snapshot
3499                        .bytes_in_range(start_ix..end_ix)
3500                        .flatten()
3501                        .copied()
3502                        .collect::<Vec<_>>(),
3503                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3504                    "bytes_in_range({:?})",
3505                    start_ix..end_ix,
3506                );
3507            }
3508        }
3509
3510        let snapshot = multibuffer.read(cx).snapshot(cx);
3511        for (old_snapshot, subscription) in old_versions {
3512            let edits = subscription.consume().into_inner();
3513
3514            log::info!(
3515                "applying subscription edits to old text: {:?}: {:?}",
3516                old_snapshot.text(),
3517                edits,
3518            );
3519
3520            let mut text = old_snapshot.text();
3521            for edit in edits {
3522                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3523                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3524            }
3525            assert_eq!(text.to_string(), snapshot.text());
3526        }
3527    }
3528
3529    #[gpui::test]
3530    fn test_history(cx: &mut MutableAppContext) {
3531        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3532        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3533        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3534        let group_interval = multibuffer.read(cx).history.group_interval;
3535        multibuffer.update(cx, |multibuffer, cx| {
3536            multibuffer.push_excerpts(buffer_1.clone(), [0..buffer_1.read(cx).len()], cx);
3537            multibuffer.push_excerpts(buffer_2.clone(), [0..buffer_2.read(cx).len()], cx);
3538        });
3539
3540        let mut now = Instant::now();
3541
3542        multibuffer.update(cx, |multibuffer, cx| {
3543            multibuffer.start_transaction_at(now, cx);
3544            multibuffer.edit(
3545                [
3546                    Point::new(0, 0)..Point::new(0, 0),
3547                    Point::new(1, 0)..Point::new(1, 0),
3548                ],
3549                "A",
3550                cx,
3551            );
3552            multibuffer.edit(
3553                [
3554                    Point::new(0, 1)..Point::new(0, 1),
3555                    Point::new(1, 1)..Point::new(1, 1),
3556                ],
3557                "B",
3558                cx,
3559            );
3560            multibuffer.end_transaction_at(now, cx);
3561            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3562
3563            now += 2 * group_interval;
3564            multibuffer.start_transaction_at(now, cx);
3565            multibuffer.edit([2..2], "C", cx);
3566            multibuffer.end_transaction_at(now, cx);
3567            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3568
3569            multibuffer.undo(cx);
3570            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3571
3572            multibuffer.undo(cx);
3573            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3574
3575            multibuffer.redo(cx);
3576            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3577
3578            multibuffer.redo(cx);
3579            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3580
3581            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3582            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3583
3584            multibuffer.undo(cx);
3585            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3586
3587            multibuffer.redo(cx);
3588            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3589
3590            multibuffer.redo(cx);
3591            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3592
3593            multibuffer.undo(cx);
3594            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3595
3596            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3597            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3598
3599            multibuffer.undo(cx);
3600            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3601        });
3602    }
3603}