multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::{Bound, HashMap};
   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    title: Option<String>,
  43}
  44
  45struct History {
  46    next_transaction_id: TransactionId,
  47    undo_stack: Vec<Transaction>,
  48    redo_stack: Vec<Transaction>,
  49    transaction_depth: usize,
  50    group_interval: Duration,
  51}
  52
  53#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug)]
  54pub enum CharKind {
  55    Newline,
  56    Punctuation,
  57    Whitespace,
  58    Word,
  59}
  60
  61struct Transaction {
  62    id: TransactionId,
  63    buffer_transactions: HashMap<usize, text::TransactionId>,
  64    first_edit_at: Instant,
  65    last_edit_at: Instant,
  66    suppress_grouping: bool,
  67}
  68
  69pub trait ToOffset: 'static + fmt::Debug {
  70    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  71}
  72
  73pub trait ToPoint: 'static + fmt::Debug {
  74    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  75}
  76
  77pub trait ToPointUtf16: 'static + fmt::Debug {
  78    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
  79}
  80
  81struct BufferState {
  82    buffer: ModelHandle<Buffer>,
  83    last_version: clock::Global,
  84    last_parse_count: usize,
  85    last_selections_update_count: usize,
  86    last_diagnostics_update_count: usize,
  87    last_file_update_count: usize,
  88    excerpts: Vec<ExcerptId>,
  89    _subscriptions: [gpui::Subscription; 2],
  90}
  91
  92#[derive(Clone, Default)]
  93pub struct MultiBufferSnapshot {
  94    singleton: bool,
  95    excerpts: SumTree<Excerpt>,
  96    parse_count: usize,
  97    diagnostics_update_count: usize,
  98    trailing_excerpt_update_count: usize,
  99    is_dirty: bool,
 100    has_conflict: bool,
 101}
 102
 103pub struct ExcerptBoundary {
 104    pub row: u32,
 105    pub buffer: BufferSnapshot,
 106    pub range: Range<text::Anchor>,
 107    pub starts_new_buffer: bool,
 108}
 109
 110#[derive(Clone)]
 111struct Excerpt {
 112    id: ExcerptId,
 113    buffer_id: usize,
 114    buffer: BufferSnapshot,
 115    range: Range<text::Anchor>,
 116    max_buffer_row: u32,
 117    text_summary: TextSummary,
 118    has_trailing_newline: bool,
 119}
 120
 121#[derive(Clone, Debug, Default)]
 122struct ExcerptSummary {
 123    excerpt_id: ExcerptId,
 124    max_buffer_row: u32,
 125    text: TextSummary,
 126}
 127
 128pub struct MultiBufferRows<'a> {
 129    buffer_row_range: Range<u32>,
 130    excerpts: Cursor<'a, Excerpt, Point>,
 131}
 132
 133pub struct MultiBufferChunks<'a> {
 134    range: Range<usize>,
 135    excerpts: Cursor<'a, Excerpt, usize>,
 136    excerpt_chunks: Option<ExcerptChunks<'a>>,
 137    language_aware: bool,
 138}
 139
 140pub struct MultiBufferBytes<'a> {
 141    range: Range<usize>,
 142    excerpts: Cursor<'a, Excerpt, usize>,
 143    excerpt_bytes: Option<ExcerptBytes<'a>>,
 144    chunk: &'a [u8],
 145}
 146
 147struct ExcerptChunks<'a> {
 148    content_chunks: BufferChunks<'a>,
 149    footer_height: usize,
 150}
 151
 152struct ExcerptBytes<'a> {
 153    content_bytes: language::rope::Bytes<'a>,
 154    footer_height: usize,
 155}
 156
 157impl MultiBuffer {
 158    pub fn new(replica_id: ReplicaId) -> Self {
 159        Self {
 160            snapshot: Default::default(),
 161            buffers: Default::default(),
 162            subscriptions: Default::default(),
 163            singleton: false,
 164            replica_id,
 165            history: History {
 166                next_transaction_id: Default::default(),
 167                undo_stack: Default::default(),
 168                redo_stack: Default::default(),
 169                transaction_depth: 0,
 170                group_interval: Duration::from_millis(300),
 171            },
 172            title: Default::default(),
 173        }
 174    }
 175
 176    pub fn with_title(mut self, title: String) -> Self {
 177        self.title = Some(title);
 178        self
 179    }
 180
 181    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 182        let mut this = Self::new(buffer.read(cx).replica_id());
 183        this.singleton = true;
 184        this.push_excerpts(buffer, [text::Anchor::min()..text::Anchor::max()], cx);
 185        this.snapshot.borrow_mut().singleton = true;
 186        this
 187    }
 188
 189    #[cfg(any(test, feature = "test-support"))]
 190    pub fn build_simple(text: &str, cx: &mut gpui::MutableAppContext) -> ModelHandle<Self> {
 191        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
 192        cx.add_model(|cx| Self::singleton(buffer, cx))
 193    }
 194
 195    #[cfg(any(test, feature = "test-support"))]
 196    pub fn build_random(
 197        rng: &mut impl rand::Rng,
 198        cx: &mut gpui::MutableAppContext,
 199    ) -> ModelHandle<Self> {
 200        cx.add_model(|cx| {
 201            let mut multibuffer = MultiBuffer::new(0);
 202            let mutation_count = rng.gen_range(1..=5);
 203            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
 204            multibuffer
 205        })
 206    }
 207
 208    pub fn replica_id(&self) -> ReplicaId {
 209        self.replica_id
 210    }
 211
 212    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 213        self.sync(cx);
 214        self.snapshot.borrow().clone()
 215    }
 216
 217    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 218        self.sync(cx);
 219        self.snapshot.borrow()
 220    }
 221
 222    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 223        if self.singleton {
 224            return Some(
 225                self.buffers
 226                    .borrow()
 227                    .values()
 228                    .next()
 229                    .unwrap()
 230                    .buffer
 231                    .clone(),
 232            );
 233        } else {
 234            None
 235        }
 236    }
 237
 238    pub fn is_singleton(&self) -> bool {
 239        self.singleton
 240    }
 241
 242    pub fn subscribe(&mut self) -> Subscription {
 243        self.subscriptions.subscribe()
 244    }
 245
 246    pub fn edit<I, S, T>(&mut self, ranges: I, new_text: T, cx: &mut ModelContext<Self>)
 247    where
 248        I: IntoIterator<Item = Range<S>>,
 249        S: ToOffset,
 250        T: Into<String>,
 251    {
 252        self.edit_internal(ranges, new_text, false, cx)
 253    }
 254
 255    pub fn edit_with_autoindent<I, S, T>(
 256        &mut self,
 257        ranges: I,
 258        new_text: T,
 259        cx: &mut ModelContext<Self>,
 260    ) where
 261        I: IntoIterator<Item = Range<S>>,
 262        S: ToOffset,
 263        T: Into<String>,
 264    {
 265        self.edit_internal(ranges, new_text, true, cx)
 266    }
 267
 268    pub fn edit_internal<I, S, T>(
 269        &mut self,
 270        ranges_iter: I,
 271        new_text: T,
 272        autoindent: bool,
 273        cx: &mut ModelContext<Self>,
 274    ) where
 275        I: IntoIterator<Item = Range<S>>,
 276        S: ToOffset,
 277        T: Into<String>,
 278    {
 279        if self.buffers.borrow().is_empty() {
 280            return;
 281        }
 282
 283        if let Some(buffer) = self.as_singleton() {
 284            let snapshot = self.read(cx);
 285            let ranges = ranges_iter
 286                .into_iter()
 287                .map(|range| range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot));
 288            return buffer.update(cx, |buffer, cx| {
 289                if autoindent {
 290                    buffer.edit_with_autoindent(ranges, new_text, cx);
 291                } else {
 292                    buffer.edit(ranges, new_text, cx);
 293                }
 294            });
 295        }
 296
 297        let snapshot = self.read(cx);
 298        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, bool)>> = Default::default();
 299        let mut cursor = snapshot.excerpts.cursor::<usize>();
 300        for range in ranges_iter {
 301            let start = range.start.to_offset(&snapshot);
 302            let end = range.end.to_offset(&snapshot);
 303            cursor.seek(&start, Bias::Right, &());
 304            if cursor.item().is_none() && start == *cursor.start() {
 305                cursor.prev(&());
 306            }
 307            let start_excerpt = cursor.item().expect("start offset out of bounds");
 308            let start_overshoot = start - cursor.start();
 309            let buffer_start =
 310                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 311
 312            cursor.seek(&end, Bias::Right, &());
 313            if cursor.item().is_none() && end == *cursor.start() {
 314                cursor.prev(&());
 315            }
 316            let end_excerpt = cursor.item().expect("end offset out of bounds");
 317            let end_overshoot = end - cursor.start();
 318            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 319
 320            if start_excerpt.id == end_excerpt.id {
 321                buffer_edits
 322                    .entry(start_excerpt.buffer_id)
 323                    .or_insert(Vec::new())
 324                    .push((buffer_start..buffer_end, true));
 325            } else {
 326                let start_excerpt_range =
 327                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 328                let end_excerpt_range =
 329                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 330                buffer_edits
 331                    .entry(start_excerpt.buffer_id)
 332                    .or_insert(Vec::new())
 333                    .push((start_excerpt_range, true));
 334                buffer_edits
 335                    .entry(end_excerpt.buffer_id)
 336                    .or_insert(Vec::new())
 337                    .push((end_excerpt_range, false));
 338
 339                cursor.seek(&start, Bias::Right, &());
 340                cursor.next(&());
 341                while let Some(excerpt) = cursor.item() {
 342                    if excerpt.id == end_excerpt.id {
 343                        break;
 344                    }
 345                    buffer_edits
 346                        .entry(excerpt.buffer_id)
 347                        .or_insert(Vec::new())
 348                        .push((excerpt.range.to_offset(&excerpt.buffer), false));
 349                    cursor.next(&());
 350                }
 351            }
 352        }
 353
 354        let new_text = new_text.into();
 355        for (buffer_id, mut edits) in buffer_edits {
 356            edits.sort_unstable_by_key(|(range, _)| range.start);
 357            self.buffers.borrow()[&buffer_id]
 358                .buffer
 359                .update(cx, |buffer, cx| {
 360                    let mut edits = edits.into_iter().peekable();
 361                    let mut insertions = Vec::new();
 362                    let mut deletions = Vec::new();
 363                    while let Some((mut range, mut is_insertion)) = edits.next() {
 364                        while let Some((next_range, next_is_insertion)) = edits.peek() {
 365                            if range.end >= next_range.start {
 366                                range.end = cmp::max(next_range.end, range.end);
 367                                is_insertion |= *next_is_insertion;
 368                                edits.next();
 369                            } else {
 370                                break;
 371                            }
 372                        }
 373
 374                        if is_insertion {
 375                            insertions.push(
 376                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 377                            );
 378                        } else if !range.is_empty() {
 379                            deletions.push(
 380                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 381                            );
 382                        }
 383                    }
 384
 385                    if autoindent {
 386                        buffer.edit_with_autoindent(deletions, "", cx);
 387                        buffer.edit_with_autoindent(insertions, new_text.clone(), cx);
 388                    } else {
 389                        buffer.edit(deletions, "", cx);
 390                        buffer.edit(insertions, new_text.clone(), cx);
 391                    }
 392                })
 393        }
 394    }
 395
 396    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 397        self.start_transaction_at(Instant::now(), cx)
 398    }
 399
 400    pub(crate) fn start_transaction_at(
 401        &mut self,
 402        now: Instant,
 403        cx: &mut ModelContext<Self>,
 404    ) -> Option<TransactionId> {
 405        if let Some(buffer) = self.as_singleton() {
 406            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 407        }
 408
 409        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 410            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 411        }
 412        self.history.start_transaction(now)
 413    }
 414
 415    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 416        self.end_transaction_at(Instant::now(), cx)
 417    }
 418
 419    pub(crate) fn end_transaction_at(
 420        &mut self,
 421        now: Instant,
 422        cx: &mut ModelContext<Self>,
 423    ) -> Option<TransactionId> {
 424        if let Some(buffer) = self.as_singleton() {
 425            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 426        }
 427
 428        let mut buffer_transactions = HashMap::default();
 429        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 430            if let Some(transaction_id) =
 431                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 432            {
 433                buffer_transactions.insert(buffer.id(), transaction_id);
 434            }
 435        }
 436
 437        if self.history.end_transaction(now, buffer_transactions) {
 438            let transaction_id = self.history.group().unwrap();
 439            Some(transaction_id)
 440        } else {
 441            None
 442        }
 443    }
 444
 445    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 446        self.history.finalize_last_transaction();
 447        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 448            buffer.update(cx, |buffer, _| {
 449                buffer.finalize_last_transaction();
 450            });
 451        }
 452    }
 453
 454    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T)
 455    where
 456        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
 457    {
 458        self.history
 459            .push_transaction(buffer_transactions, Instant::now());
 460        self.history.finalize_last_transaction();
 461    }
 462
 463    pub fn set_active_selections(
 464        &mut self,
 465        selections: &[Selection<Anchor>],
 466        cx: &mut ModelContext<Self>,
 467    ) {
 468        let mut selections_by_buffer: HashMap<usize, Vec<Selection<text::Anchor>>> =
 469            Default::default();
 470        let snapshot = self.read(cx);
 471        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 472        for selection in selections {
 473            cursor.seek(&Some(&selection.start.excerpt_id), Bias::Left, &());
 474            while let Some(excerpt) = cursor.item() {
 475                if excerpt.id > selection.end.excerpt_id {
 476                    break;
 477                }
 478
 479                let mut start = excerpt.range.start.clone();
 480                let mut end = excerpt.range.end.clone();
 481                if excerpt.id == selection.start.excerpt_id {
 482                    start = selection.start.text_anchor.clone();
 483                }
 484                if excerpt.id == selection.end.excerpt_id {
 485                    end = selection.end.text_anchor.clone();
 486                }
 487                selections_by_buffer
 488                    .entry(excerpt.buffer_id)
 489                    .or_default()
 490                    .push(Selection {
 491                        id: selection.id,
 492                        start,
 493                        end,
 494                        reversed: selection.reversed,
 495                        goal: selection.goal,
 496                    });
 497
 498                cursor.next(&());
 499            }
 500        }
 501
 502        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 503            if !selections_by_buffer.contains_key(buffer_id) {
 504                buffer_state
 505                    .buffer
 506                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 507            }
 508        }
 509
 510        for (buffer_id, mut selections) in selections_by_buffer {
 511            self.buffers.borrow()[&buffer_id]
 512                .buffer
 513                .update(cx, |buffer, cx| {
 514                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer).unwrap());
 515                    let mut selections = selections.into_iter().peekable();
 516                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 517                        let mut selection = selections.next()?;
 518                        while let Some(next_selection) = selections.peek() {
 519                            if selection
 520                                .end
 521                                .cmp(&next_selection.start, buffer)
 522                                .unwrap()
 523                                .is_ge()
 524                            {
 525                                let next_selection = selections.next().unwrap();
 526                                if next_selection
 527                                    .end
 528                                    .cmp(&selection.end, buffer)
 529                                    .unwrap()
 530                                    .is_ge()
 531                                {
 532                                    selection.end = next_selection.end;
 533                                }
 534                            } else {
 535                                break;
 536                            }
 537                        }
 538                        Some(selection)
 539                    }));
 540                    buffer.set_active_selections(merged_selections, cx);
 541                });
 542        }
 543    }
 544
 545    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 546        for buffer in self.buffers.borrow().values() {
 547            buffer
 548                .buffer
 549                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 550        }
 551    }
 552
 553    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 554        if let Some(buffer) = self.as_singleton() {
 555            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 556        }
 557
 558        while let Some(transaction) = self.history.pop_undo() {
 559            let mut undone = false;
 560            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 561                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 562                    undone |= buffer.update(cx, |buffer, cx| {
 563                        let undo_to = *buffer_transaction_id;
 564                        if let Some(entry) = buffer.peek_undo_stack() {
 565                            *buffer_transaction_id = entry.transaction_id();
 566                        }
 567                        buffer.undo_to_transaction(undo_to, cx)
 568                    });
 569                }
 570            }
 571
 572            if undone {
 573                return Some(transaction.id);
 574            }
 575        }
 576
 577        None
 578    }
 579
 580    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 581        if let Some(buffer) = self.as_singleton() {
 582            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 583        }
 584
 585        while let Some(transaction) = self.history.pop_redo() {
 586            let mut redone = false;
 587            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 588                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 589                    redone |= buffer.update(cx, |buffer, cx| {
 590                        let redo_to = *buffer_transaction_id;
 591                        if let Some(entry) = buffer.peek_redo_stack() {
 592                            *buffer_transaction_id = entry.transaction_id();
 593                        }
 594                        buffer.redo_to_transaction(redo_to, cx)
 595                    });
 596                }
 597            }
 598
 599            if redone {
 600                return Some(transaction.id);
 601            }
 602        }
 603
 604        None
 605    }
 606
 607    pub fn push_excerpts<O>(
 608        &mut self,
 609        buffer: ModelHandle<Buffer>,
 610        ranges: impl IntoIterator<Item = Range<O>>,
 611        cx: &mut ModelContext<Self>,
 612    ) -> Vec<ExcerptId>
 613    where
 614        O: text::ToOffset,
 615    {
 616        self.insert_excerpts_after(&ExcerptId::max(), buffer, ranges, cx)
 617    }
 618
 619    pub fn push_excerpts_with_context_lines<O>(
 620        &mut self,
 621        buffer: ModelHandle<Buffer>,
 622        ranges: Vec<Range<O>>,
 623        context_line_count: u32,
 624        cx: &mut ModelContext<Self>,
 625    ) -> Vec<Range<Anchor>>
 626    where
 627        O: text::ToPoint + text::ToOffset,
 628    {
 629        let buffer_id = buffer.id();
 630        let buffer_snapshot = buffer.read(cx).snapshot();
 631        let max_point = buffer_snapshot.max_point();
 632
 633        let mut range_counts = Vec::new();
 634        let mut excerpt_ranges = Vec::new();
 635        let mut range_iter = ranges
 636            .iter()
 637            .map(|range| {
 638                range.start.to_point(&buffer_snapshot)..range.end.to_point(&buffer_snapshot)
 639            })
 640            .peekable();
 641        while let Some(range) = range_iter.next() {
 642            let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
 643            let mut excerpt_end =
 644                Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
 645            let mut ranges_in_excerpt = 1;
 646
 647            while let Some(next_range) = range_iter.peek() {
 648                if next_range.start.row <= excerpt_end.row + context_line_count {
 649                    excerpt_end =
 650                        Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
 651                    ranges_in_excerpt += 1;
 652                    range_iter.next();
 653                } else {
 654                    break;
 655                }
 656            }
 657
 658            excerpt_ranges.push(excerpt_start..excerpt_end);
 659            range_counts.push(ranges_in_excerpt);
 660        }
 661
 662        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
 663
 664        let mut anchor_ranges = Vec::new();
 665        let mut ranges = ranges.into_iter();
 666        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
 667            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
 668                let start = Anchor {
 669                    buffer_id,
 670                    excerpt_id: excerpt_id.clone(),
 671                    text_anchor: buffer_snapshot.anchor_after(range.start),
 672                };
 673                let end = Anchor {
 674                    buffer_id,
 675                    excerpt_id: excerpt_id.clone(),
 676                    text_anchor: buffer_snapshot.anchor_after(range.end),
 677                };
 678                start..end
 679            }))
 680        }
 681        anchor_ranges
 682    }
 683
 684    pub fn insert_excerpts_after<O>(
 685        &mut self,
 686        prev_excerpt_id: &ExcerptId,
 687        buffer: ModelHandle<Buffer>,
 688        ranges: impl IntoIterator<Item = Range<O>>,
 689        cx: &mut ModelContext<Self>,
 690    ) -> Vec<ExcerptId>
 691    where
 692        O: text::ToOffset,
 693    {
 694        assert_eq!(self.history.transaction_depth, 0);
 695        self.sync(cx);
 696
 697        let buffer_id = buffer.id();
 698        let buffer_snapshot = buffer.read(cx).snapshot();
 699
 700        let mut buffers = self.buffers.borrow_mut();
 701        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
 702            last_version: buffer_snapshot.version().clone(),
 703            last_parse_count: buffer_snapshot.parse_count(),
 704            last_selections_update_count: buffer_snapshot.selections_update_count(),
 705            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 706            last_file_update_count: buffer_snapshot.file_update_count(),
 707            excerpts: Default::default(),
 708            _subscriptions: [
 709                cx.observe(&buffer, |_, _, cx| cx.notify()),
 710                cx.subscribe(&buffer, Self::on_buffer_event),
 711            ],
 712            buffer,
 713        });
 714
 715        let mut snapshot = self.snapshot.borrow_mut();
 716        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 717        let mut new_excerpts = cursor.slice(&Some(prev_excerpt_id), Bias::Right, &());
 718
 719        let mut prev_id = ExcerptId::min();
 720        let edit_start = new_excerpts.summary().text.bytes;
 721        new_excerpts.update_last(
 722            |excerpt| {
 723                excerpt.has_trailing_newline = true;
 724                prev_id = excerpt.id.clone();
 725            },
 726            &(),
 727        );
 728
 729        let mut next_id = ExcerptId::max();
 730        if let Some(next_excerpt) = cursor.item() {
 731            next_id = next_excerpt.id.clone();
 732        }
 733
 734        let mut ids = Vec::new();
 735        let mut ranges = ranges.into_iter().peekable();
 736        while let Some(range) = ranges.next() {
 737            let id = ExcerptId::between(&prev_id, &next_id);
 738            if let Err(ix) = buffer_state.excerpts.binary_search(&id) {
 739                buffer_state.excerpts.insert(ix, id.clone());
 740            }
 741            let range = buffer_snapshot.anchor_before(&range.start)
 742                ..buffer_snapshot.anchor_after(&range.end);
 743            let excerpt = Excerpt::new(
 744                id.clone(),
 745                buffer_id,
 746                buffer_snapshot.clone(),
 747                range,
 748                ranges.peek().is_some() || cursor.item().is_some(),
 749            );
 750            new_excerpts.push(excerpt, &());
 751            prev_id = id.clone();
 752            ids.push(id);
 753        }
 754
 755        let edit_end = new_excerpts.summary().text.bytes;
 756
 757        let suffix = cursor.suffix(&());
 758        let changed_trailing_excerpt = suffix.is_empty();
 759        new_excerpts.push_tree(suffix, &());
 760        drop(cursor);
 761        snapshot.excerpts = new_excerpts;
 762        if changed_trailing_excerpt {
 763            snapshot.trailing_excerpt_update_count += 1;
 764        }
 765
 766        self.subscriptions.publish_mut([Edit {
 767            old: edit_start..edit_start,
 768            new: edit_start..edit_end,
 769        }]);
 770
 771        cx.notify();
 772        ids
 773    }
 774
 775    pub fn excerpt_ids_for_buffer(&self, buffer: &ModelHandle<Buffer>) -> Vec<ExcerptId> {
 776        self.buffers
 777            .borrow()
 778            .get(&buffer.id())
 779            .map_or(Vec::new(), |state| state.excerpts.clone())
 780    }
 781
 782    pub fn excerpted_buffers<'a, T: ToOffset>(
 783        &'a self,
 784        range: Range<T>,
 785        cx: &AppContext,
 786    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 787        let snapshot = self.snapshot(cx);
 788        let start = range.start.to_offset(&snapshot);
 789        let end = range.end.to_offset(&snapshot);
 790
 791        let mut result = Vec::new();
 792        let mut cursor = snapshot.excerpts.cursor::<usize>();
 793        cursor.seek(&start, Bias::Right, &());
 794        while let Some(excerpt) = cursor.item() {
 795            if *cursor.start() > end {
 796                break;
 797            }
 798
 799            let mut end_before_newline = cursor.end(&());
 800            if excerpt.has_trailing_newline {
 801                end_before_newline -= 1;
 802            }
 803            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 804            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 805            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 806            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 807            result.push((buffer, start..end));
 808            cursor.next(&());
 809        }
 810
 811        result
 812    }
 813
 814    pub fn remove_excerpts<'a>(
 815        &mut self,
 816        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 817        cx: &mut ModelContext<Self>,
 818    ) {
 819        let mut buffers = self.buffers.borrow_mut();
 820        let mut snapshot = self.snapshot.borrow_mut();
 821        let mut new_excerpts = SumTree::new();
 822        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 823        let mut edits = Vec::new();
 824        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 825
 826        while let Some(mut excerpt_id) = excerpt_ids.next() {
 827            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 828            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 829            if let Some(mut excerpt) = cursor.item() {
 830                if excerpt.id != *excerpt_id {
 831                    continue;
 832                }
 833                let mut old_start = cursor.start().1;
 834
 835                // Skip over the removed excerpt.
 836                loop {
 837                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 838                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 839                        if buffer_state.excerpts.is_empty() {
 840                            buffers.remove(&excerpt.buffer_id);
 841                        }
 842                    }
 843                    cursor.next(&());
 844
 845                    // Skip over any subsequent excerpts that are also removed.
 846                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 847                        if let Some(next_excerpt) = cursor.item() {
 848                            if next_excerpt.id == *next_excerpt_id {
 849                                excerpt = next_excerpt;
 850                                excerpt_id = excerpt_ids.next().unwrap();
 851                                continue;
 852                            }
 853                        }
 854                    }
 855
 856                    break;
 857                }
 858
 859                // When removing the last excerpt, remove the trailing newline from
 860                // the previous excerpt.
 861                if cursor.item().is_none() && old_start > 0 {
 862                    old_start -= 1;
 863                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 864                }
 865
 866                // Push an edit for the removal of this run of excerpts.
 867                let old_end = cursor.start().1;
 868                let new_start = new_excerpts.summary().text.bytes;
 869                edits.push(Edit {
 870                    old: old_start..old_end,
 871                    new: new_start..new_start,
 872                });
 873            }
 874        }
 875        let suffix = cursor.suffix(&());
 876        let changed_trailing_excerpt = suffix.is_empty();
 877        new_excerpts.push_tree(suffix, &());
 878        drop(cursor);
 879        snapshot.excerpts = new_excerpts;
 880        if changed_trailing_excerpt {
 881            snapshot.trailing_excerpt_update_count += 1;
 882        }
 883
 884        self.subscriptions.publish_mut(edits);
 885        cx.notify();
 886    }
 887
 888    pub fn text_anchor_for_position<'a, T: ToOffset>(
 889        &'a self,
 890        position: T,
 891        cx: &AppContext,
 892    ) -> (ModelHandle<Buffer>, language::Anchor) {
 893        let snapshot = self.read(cx);
 894        let anchor = snapshot.anchor_before(position);
 895        (
 896            self.buffers.borrow()[&anchor.buffer_id].buffer.clone(),
 897            anchor.text_anchor,
 898        )
 899    }
 900
 901    fn on_buffer_event(
 902        &mut self,
 903        _: ModelHandle<Buffer>,
 904        event: &Event,
 905        cx: &mut ModelContext<Self>,
 906    ) {
 907        cx.emit(event.clone());
 908    }
 909
 910    pub fn format(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 911        let mut format_tasks = Vec::new();
 912        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 913            format_tasks.push(buffer.update(cx, |buffer, cx| buffer.format(cx)));
 914        }
 915
 916        cx.spawn(|_, _| async move {
 917            for format in format_tasks {
 918                format.await?;
 919            }
 920            Ok(())
 921        })
 922    }
 923
 924    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 925        let mut save_tasks = Vec::new();
 926        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 927            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx)));
 928        }
 929
 930        cx.spawn(|_, _| async move {
 931            for save in save_tasks {
 932                save.await?;
 933            }
 934            Ok(())
 935        })
 936    }
 937
 938    pub fn is_completion_trigger<T>(&self, position: T, text: &str, cx: &AppContext) -> bool
 939    where
 940        T: ToOffset,
 941    {
 942        let mut chars = text.chars();
 943        let char = if let Some(char) = chars.next() {
 944            char
 945        } else {
 946            return false;
 947        };
 948        if chars.next().is_some() {
 949            return false;
 950        }
 951
 952        if char.is_alphanumeric() || char == '_' {
 953            return true;
 954        }
 955
 956        let snapshot = self.snapshot(cx);
 957        let anchor = snapshot.anchor_before(position);
 958        let buffer = self.buffers.borrow()[&anchor.buffer_id].buffer.clone();
 959        buffer
 960            .read(cx)
 961            .completion_triggers()
 962            .iter()
 963            .any(|string| string == text)
 964    }
 965
 966    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 967        self.buffers
 968            .borrow()
 969            .values()
 970            .next()
 971            .and_then(|state| state.buffer.read(cx).language())
 972    }
 973
 974    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 975        self.as_singleton()?.read(cx).file()
 976    }
 977
 978    pub fn title(&self, cx: &AppContext) -> String {
 979        if let Some(title) = self.title.clone() {
 980            title
 981        } else if let Some(file) = self.file(cx) {
 982            file.file_name(cx).to_string_lossy().into()
 983        } else {
 984            "untitled".into()
 985        }
 986    }
 987
 988    #[cfg(test)]
 989    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 990        self.as_singleton().unwrap().read(cx).is_parsing()
 991    }
 992
 993    fn sync(&self, cx: &AppContext) {
 994        let mut snapshot = self.snapshot.borrow_mut();
 995        let mut excerpts_to_edit = Vec::new();
 996        let mut reparsed = false;
 997        let mut diagnostics_updated = false;
 998        let mut is_dirty = false;
 999        let mut has_conflict = false;
1000        let mut buffers = self.buffers.borrow_mut();
1001        for buffer_state in buffers.values_mut() {
1002            let buffer = buffer_state.buffer.read(cx);
1003            let version = buffer.version();
1004            let parse_count = buffer.parse_count();
1005            let selections_update_count = buffer.selections_update_count();
1006            let diagnostics_update_count = buffer.diagnostics_update_count();
1007            let file_update_count = buffer.file_update_count();
1008
1009            let buffer_edited = version.changed_since(&buffer_state.last_version);
1010            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1011            let buffer_selections_updated =
1012                selections_update_count > buffer_state.last_selections_update_count;
1013            let buffer_diagnostics_updated =
1014                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1015            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1016            if buffer_edited
1017                || buffer_reparsed
1018                || buffer_selections_updated
1019                || buffer_diagnostics_updated
1020                || buffer_file_updated
1021            {
1022                buffer_state.last_version = version;
1023                buffer_state.last_parse_count = parse_count;
1024                buffer_state.last_selections_update_count = selections_update_count;
1025                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1026                buffer_state.last_file_update_count = file_update_count;
1027                excerpts_to_edit.extend(
1028                    buffer_state
1029                        .excerpts
1030                        .iter()
1031                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
1032                );
1033            }
1034
1035            reparsed |= buffer_reparsed;
1036            diagnostics_updated |= buffer_diagnostics_updated;
1037            is_dirty |= buffer.is_dirty();
1038            has_conflict |= buffer.has_conflict();
1039        }
1040        if reparsed {
1041            snapshot.parse_count += 1;
1042        }
1043        if diagnostics_updated {
1044            snapshot.diagnostics_update_count += 1;
1045        }
1046        snapshot.is_dirty = is_dirty;
1047        snapshot.has_conflict = has_conflict;
1048
1049        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
1050
1051        let mut edits = Vec::new();
1052        let mut new_excerpts = SumTree::new();
1053        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
1054
1055        for (id, buffer, buffer_edited) in excerpts_to_edit {
1056            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
1057            let old_excerpt = cursor.item().unwrap();
1058            let buffer_id = buffer.id();
1059            let buffer = buffer.read(cx);
1060
1061            let mut new_excerpt;
1062            if buffer_edited {
1063                edits.extend(
1064                    buffer
1065                        .edits_since_in_range::<usize>(
1066                            old_excerpt.buffer.version(),
1067                            old_excerpt.range.clone(),
1068                        )
1069                        .map(|mut edit| {
1070                            let excerpt_old_start = cursor.start().1;
1071                            let excerpt_new_start = new_excerpts.summary().text.bytes;
1072                            edit.old.start += excerpt_old_start;
1073                            edit.old.end += excerpt_old_start;
1074                            edit.new.start += excerpt_new_start;
1075                            edit.new.end += excerpt_new_start;
1076                            edit
1077                        }),
1078                );
1079
1080                new_excerpt = Excerpt::new(
1081                    id.clone(),
1082                    buffer_id,
1083                    buffer.snapshot(),
1084                    old_excerpt.range.clone(),
1085                    old_excerpt.has_trailing_newline,
1086                );
1087            } else {
1088                new_excerpt = old_excerpt.clone();
1089                new_excerpt.buffer = buffer.snapshot();
1090            }
1091
1092            new_excerpts.push(new_excerpt, &());
1093            cursor.next(&());
1094        }
1095        new_excerpts.push_tree(cursor.suffix(&()), &());
1096
1097        drop(cursor);
1098        snapshot.excerpts = new_excerpts;
1099
1100        self.subscriptions.publish(edits);
1101    }
1102}
1103
1104#[cfg(any(test, feature = "test-support"))]
1105impl MultiBuffer {
1106    pub fn randomly_edit(
1107        &mut self,
1108        rng: &mut impl rand::Rng,
1109        count: usize,
1110        cx: &mut ModelContext<Self>,
1111    ) {
1112        use text::RandomCharIter;
1113
1114        let snapshot = self.read(cx);
1115        let mut old_ranges: Vec<Range<usize>> = Vec::new();
1116        for _ in 0..count {
1117            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
1118            if last_end > snapshot.len() {
1119                break;
1120            }
1121            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
1122            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1123            old_ranges.push(start_ix..end_ix);
1124        }
1125        let new_text_len = rng.gen_range(0..10);
1126        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1127        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
1128        drop(snapshot);
1129
1130        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
1131    }
1132
1133    pub fn randomly_edit_excerpts(
1134        &mut self,
1135        rng: &mut impl rand::Rng,
1136        mutation_count: usize,
1137        cx: &mut ModelContext<Self>,
1138    ) {
1139        use rand::prelude::*;
1140        use std::env;
1141        use text::RandomCharIter;
1142
1143        let max_excerpts = env::var("MAX_EXCERPTS")
1144            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1145            .unwrap_or(5);
1146
1147        let mut buffers = Vec::new();
1148        for _ in 0..mutation_count {
1149            let excerpt_ids = self
1150                .buffers
1151                .borrow()
1152                .values()
1153                .flat_map(|b| &b.excerpts)
1154                .cloned()
1155                .collect::<Vec<_>>();
1156            if excerpt_ids.len() == 0 || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1157                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1158                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1159                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
1160                    let buffer = buffers.last().unwrap();
1161                    log::info!(
1162                        "Creating new buffer {} with text: {:?}",
1163                        buffer.id(),
1164                        buffer.read(cx).text()
1165                    );
1166                    buffers.last().unwrap().clone()
1167                } else {
1168                    self.buffers
1169                        .borrow()
1170                        .values()
1171                        .choose(rng)
1172                        .unwrap()
1173                        .buffer
1174                        .clone()
1175                };
1176
1177                let buffer = buffer_handle.read(cx);
1178                let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1179                let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1180                log::info!(
1181                    "Inserting excerpt from buffer {} and range {:?}: {:?}",
1182                    buffer_handle.id(),
1183                    start_ix..end_ix,
1184                    &buffer.text()[start_ix..end_ix]
1185                );
1186
1187                let excerpt_id = self.push_excerpts(buffer_handle.clone(), [start_ix..end_ix], cx);
1188                log::info!("Inserted with id: {:?}", excerpt_id);
1189            } else {
1190                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1191                let mut excerpts_to_remove = excerpt_ids
1192                    .choose_multiple(rng, remove_count)
1193                    .cloned()
1194                    .collect::<Vec<_>>();
1195                excerpts_to_remove.sort();
1196                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1197                self.remove_excerpts(&excerpts_to_remove, cx);
1198            }
1199        }
1200    }
1201
1202    pub fn randomly_mutate(
1203        &mut self,
1204        rng: &mut impl rand::Rng,
1205        mutation_count: usize,
1206        cx: &mut ModelContext<Self>,
1207    ) {
1208        if rng.gen_bool(0.7) || self.singleton {
1209            self.randomly_edit(rng, mutation_count, cx);
1210        } else {
1211            self.randomly_edit_excerpts(rng, mutation_count, cx);
1212        }
1213    }
1214}
1215
1216impl Entity for MultiBuffer {
1217    type Event = language::Event;
1218}
1219
1220impl MultiBufferSnapshot {
1221    pub fn text(&self) -> String {
1222        self.chunks(0..self.len(), false)
1223            .map(|chunk| chunk.text)
1224            .collect()
1225    }
1226
1227    pub fn reversed_chars_at<'a, T: ToOffset>(
1228        &'a self,
1229        position: T,
1230    ) -> impl Iterator<Item = char> + 'a {
1231        let mut offset = position.to_offset(self);
1232        let mut cursor = self.excerpts.cursor::<usize>();
1233        cursor.seek(&offset, Bias::Left, &());
1234        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1235            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1236            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1237            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1238            excerpt.buffer.reversed_chunks_in_range(start..end)
1239        });
1240        iter::from_fn(move || {
1241            if offset == *cursor.start() {
1242                cursor.prev(&());
1243                let excerpt = cursor.item()?;
1244                excerpt_chunks = Some(
1245                    excerpt
1246                        .buffer
1247                        .reversed_chunks_in_range(excerpt.range.clone()),
1248                );
1249            }
1250
1251            let excerpt = cursor.item().unwrap();
1252            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1253                offset -= 1;
1254                Some("\n")
1255            } else {
1256                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1257                offset -= chunk.len();
1258                Some(chunk)
1259            }
1260        })
1261        .flat_map(|c| c.chars().rev())
1262    }
1263
1264    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1265        let offset = position.to_offset(self);
1266        self.text_for_range(offset..self.len())
1267            .flat_map(|chunk| chunk.chars())
1268    }
1269
1270    pub fn text_for_range<'a, T: ToOffset>(
1271        &'a self,
1272        range: Range<T>,
1273    ) -> impl Iterator<Item = &'a str> {
1274        self.chunks(range, false).map(|chunk| chunk.text)
1275    }
1276
1277    pub fn is_line_blank(&self, row: u32) -> bool {
1278        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1279            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1280    }
1281
1282    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1283    where
1284        T: ToOffset,
1285    {
1286        let position = position.to_offset(self);
1287        position == self.clip_offset(position, Bias::Left)
1288            && self
1289                .bytes_in_range(position..self.len())
1290                .flatten()
1291                .copied()
1292                .take(needle.len())
1293                .eq(needle.bytes())
1294    }
1295
1296    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
1297        let mut start = start.to_offset(self);
1298        let mut end = start;
1299        let mut next_chars = self.chars_at(start).peekable();
1300        let mut prev_chars = self.reversed_chars_at(start).peekable();
1301        let word_kind = cmp::max(
1302            prev_chars.peek().copied().map(char_kind),
1303            next_chars.peek().copied().map(char_kind),
1304        );
1305
1306        for ch in prev_chars {
1307            if Some(char_kind(ch)) == word_kind {
1308                start -= ch.len_utf8();
1309            } else {
1310                break;
1311            }
1312        }
1313
1314        for ch in next_chars {
1315            if Some(char_kind(ch)) == word_kind {
1316                end += ch.len_utf8();
1317            } else {
1318                break;
1319            }
1320        }
1321
1322        (start..end, word_kind)
1323    }
1324
1325    fn as_singleton(&self) -> Option<&Excerpt> {
1326        if self.singleton {
1327            self.excerpts.iter().next()
1328        } else {
1329            None
1330        }
1331    }
1332
1333    pub fn len(&self) -> usize {
1334        self.excerpts.summary().text.bytes
1335    }
1336
1337    pub fn max_buffer_row(&self) -> u32 {
1338        self.excerpts.summary().max_buffer_row
1339    }
1340
1341    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1342        if let Some(excerpt) = self.as_singleton() {
1343            return excerpt.buffer.clip_offset(offset, bias);
1344        }
1345
1346        let mut cursor = self.excerpts.cursor::<usize>();
1347        cursor.seek(&offset, Bias::Right, &());
1348        let overshoot = if let Some(excerpt) = cursor.item() {
1349            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1350            let buffer_offset = excerpt
1351                .buffer
1352                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1353            buffer_offset.saturating_sub(excerpt_start)
1354        } else {
1355            0
1356        };
1357        cursor.start() + overshoot
1358    }
1359
1360    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1361        if let Some(excerpt) = self.as_singleton() {
1362            return excerpt.buffer.clip_point(point, bias);
1363        }
1364
1365        let mut cursor = self.excerpts.cursor::<Point>();
1366        cursor.seek(&point, Bias::Right, &());
1367        let overshoot = if let Some(excerpt) = cursor.item() {
1368            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1369            let buffer_point = excerpt
1370                .buffer
1371                .clip_point(excerpt_start + (point - cursor.start()), bias);
1372            buffer_point.saturating_sub(excerpt_start)
1373        } else {
1374            Point::zero()
1375        };
1376        *cursor.start() + overshoot
1377    }
1378
1379    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1380        if let Some(excerpt) = self.as_singleton() {
1381            return excerpt.buffer.clip_point_utf16(point, bias);
1382        }
1383
1384        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1385        cursor.seek(&point, Bias::Right, &());
1386        let overshoot = if let Some(excerpt) = cursor.item() {
1387            let excerpt_start = excerpt
1388                .buffer
1389                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1390            let buffer_point = excerpt
1391                .buffer
1392                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1393            buffer_point.saturating_sub(excerpt_start)
1394        } else {
1395            PointUtf16::zero()
1396        };
1397        *cursor.start() + overshoot
1398    }
1399
1400    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1401        let range = range.start.to_offset(self)..range.end.to_offset(self);
1402        let mut excerpts = self.excerpts.cursor::<usize>();
1403        excerpts.seek(&range.start, Bias::Right, &());
1404
1405        let mut chunk = &[][..];
1406        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1407            let mut excerpt_bytes = excerpt
1408                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1409            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1410            Some(excerpt_bytes)
1411        } else {
1412            None
1413        };
1414
1415        MultiBufferBytes {
1416            range,
1417            excerpts,
1418            excerpt_bytes,
1419            chunk,
1420        }
1421    }
1422
1423    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1424        let mut result = MultiBufferRows {
1425            buffer_row_range: 0..0,
1426            excerpts: self.excerpts.cursor(),
1427        };
1428        result.seek(start_row);
1429        result
1430    }
1431
1432    pub fn chunks<'a, T: ToOffset>(
1433        &'a self,
1434        range: Range<T>,
1435        language_aware: bool,
1436    ) -> MultiBufferChunks<'a> {
1437        let range = range.start.to_offset(self)..range.end.to_offset(self);
1438        let mut chunks = MultiBufferChunks {
1439            range: range.clone(),
1440            excerpts: self.excerpts.cursor(),
1441            excerpt_chunks: None,
1442            language_aware,
1443        };
1444        chunks.seek(range.start);
1445        chunks
1446    }
1447
1448    pub fn offset_to_point(&self, offset: usize) -> Point {
1449        if let Some(excerpt) = self.as_singleton() {
1450            return excerpt.buffer.offset_to_point(offset);
1451        }
1452
1453        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1454        cursor.seek(&offset, Bias::Right, &());
1455        if let Some(excerpt) = cursor.item() {
1456            let (start_offset, start_point) = cursor.start();
1457            let overshoot = offset - start_offset;
1458            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1459            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1460            let buffer_point = excerpt
1461                .buffer
1462                .offset_to_point(excerpt_start_offset + overshoot);
1463            *start_point + (buffer_point - excerpt_start_point)
1464        } else {
1465            self.excerpts.summary().text.lines
1466        }
1467    }
1468
1469    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
1470        if let Some(excerpt) = self.as_singleton() {
1471            return excerpt.buffer.offset_to_point_utf16(offset);
1472        }
1473
1474        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
1475        cursor.seek(&offset, Bias::Right, &());
1476        if let Some(excerpt) = cursor.item() {
1477            let (start_offset, start_point) = cursor.start();
1478            let overshoot = offset - start_offset;
1479            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1480            let excerpt_start_point = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1481            let buffer_point = excerpt
1482                .buffer
1483                .offset_to_point_utf16(excerpt_start_offset + overshoot);
1484            *start_point + (buffer_point - excerpt_start_point)
1485        } else {
1486            self.excerpts.summary().text.lines_utf16
1487        }
1488    }
1489
1490    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
1491        if let Some(excerpt) = self.as_singleton() {
1492            return excerpt.buffer.point_to_point_utf16(point);
1493        }
1494
1495        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
1496        cursor.seek(&point, Bias::Right, &());
1497        if let Some(excerpt) = cursor.item() {
1498            let (start_offset, start_point) = cursor.start();
1499            let overshoot = point - start_offset;
1500            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1501            let excerpt_start_point_utf16 = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1502            let buffer_point = excerpt
1503                .buffer
1504                .point_to_point_utf16(excerpt_start_point + overshoot);
1505            *start_point + (buffer_point - excerpt_start_point_utf16)
1506        } else {
1507            self.excerpts.summary().text.lines_utf16
1508        }
1509    }
1510
1511    pub fn point_to_offset(&self, point: Point) -> usize {
1512        if let Some(excerpt) = self.as_singleton() {
1513            return excerpt.buffer.point_to_offset(point);
1514        }
1515
1516        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1517        cursor.seek(&point, Bias::Right, &());
1518        if let Some(excerpt) = cursor.item() {
1519            let (start_point, start_offset) = cursor.start();
1520            let overshoot = point - start_point;
1521            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1522            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1523            let buffer_offset = excerpt
1524                .buffer
1525                .point_to_offset(excerpt_start_point + overshoot);
1526            *start_offset + buffer_offset - excerpt_start_offset
1527        } else {
1528            self.excerpts.summary().text.bytes
1529        }
1530    }
1531
1532    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1533        if let Some(excerpt) = self.as_singleton() {
1534            return excerpt.buffer.point_utf16_to_offset(point);
1535        }
1536
1537        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1538        cursor.seek(&point, Bias::Right, &());
1539        if let Some(excerpt) = cursor.item() {
1540            let (start_point, start_offset) = cursor.start();
1541            let overshoot = point - start_point;
1542            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1543            let excerpt_start_point = excerpt
1544                .buffer
1545                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1546            let buffer_offset = excerpt
1547                .buffer
1548                .point_utf16_to_offset(excerpt_start_point + overshoot);
1549            *start_offset + (buffer_offset - excerpt_start_offset)
1550        } else {
1551            self.excerpts.summary().text.bytes
1552        }
1553    }
1554
1555    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1556        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1557            buffer
1558                .indent_column_for_line(range.start.row)
1559                .min(range.end.column)
1560                .saturating_sub(range.start.column)
1561        } else {
1562            0
1563        }
1564    }
1565
1566    pub fn line_len(&self, row: u32) -> u32 {
1567        if let Some((_, range)) = self.buffer_line_for_row(row) {
1568            range.end.column - range.start.column
1569        } else {
1570            0
1571        }
1572    }
1573
1574    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1575        let mut cursor = self.excerpts.cursor::<Point>();
1576        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1577        if let Some(excerpt) = cursor.item() {
1578            let overshoot = row - cursor.start().row;
1579            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1580            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1581            let buffer_row = excerpt_start.row + overshoot;
1582            let line_start = Point::new(buffer_row, 0);
1583            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1584            return Some((
1585                &excerpt.buffer,
1586                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1587            ));
1588        }
1589        None
1590    }
1591
1592    pub fn max_point(&self) -> Point {
1593        self.text_summary().lines
1594    }
1595
1596    pub fn text_summary(&self) -> TextSummary {
1597        self.excerpts.summary().text
1598    }
1599
1600    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1601    where
1602        D: TextDimension,
1603        O: ToOffset,
1604    {
1605        let mut summary = D::default();
1606        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1607        let mut cursor = self.excerpts.cursor::<usize>();
1608        cursor.seek(&range.start, Bias::Right, &());
1609        if let Some(excerpt) = cursor.item() {
1610            let mut end_before_newline = cursor.end(&());
1611            if excerpt.has_trailing_newline {
1612                end_before_newline -= 1;
1613            }
1614
1615            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1616            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1617            let end_in_excerpt =
1618                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1619            summary.add_assign(
1620                &excerpt
1621                    .buffer
1622                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1623            );
1624
1625            if range.end > end_before_newline {
1626                summary.add_assign(&D::from_text_summary(&TextSummary {
1627                    bytes: 1,
1628                    lines: Point::new(1 as u32, 0),
1629                    lines_utf16: PointUtf16::new(1 as u32, 0),
1630                    first_line_chars: 0,
1631                    last_line_chars: 0,
1632                    longest_row: 0,
1633                    longest_row_chars: 0,
1634                }));
1635            }
1636
1637            cursor.next(&());
1638        }
1639
1640        if range.end > *cursor.start() {
1641            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1642                &range.end,
1643                Bias::Right,
1644                &(),
1645            )));
1646            if let Some(excerpt) = cursor.item() {
1647                range.end = cmp::max(*cursor.start(), range.end);
1648
1649                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1650                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1651                summary.add_assign(
1652                    &excerpt
1653                        .buffer
1654                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1655                );
1656            }
1657        }
1658
1659        summary
1660    }
1661
1662    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1663    where
1664        D: TextDimension + Ord + Sub<D, Output = D>,
1665    {
1666        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1667        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1668        if cursor.item().is_none() {
1669            cursor.next(&());
1670        }
1671
1672        let mut position = D::from_text_summary(&cursor.start().text);
1673        if let Some(excerpt) = cursor.item() {
1674            if excerpt.id == anchor.excerpt_id && excerpt.buffer_id == anchor.buffer_id {
1675                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1676                let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1677                let buffer_position = cmp::min(
1678                    excerpt_buffer_end,
1679                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
1680                );
1681                if buffer_position > excerpt_buffer_start {
1682                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1683                }
1684            }
1685        }
1686        position
1687    }
1688
1689    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1690    where
1691        D: TextDimension + Ord + Sub<D, Output = D>,
1692        I: 'a + IntoIterator<Item = &'a Anchor>,
1693    {
1694        if let Some(excerpt) = self.as_singleton() {
1695            return excerpt
1696                .buffer
1697                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
1698                .collect();
1699        }
1700
1701        let mut anchors = anchors.into_iter().peekable();
1702        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1703        let mut summaries = Vec::new();
1704        while let Some(anchor) = anchors.peek() {
1705            let excerpt_id = &anchor.excerpt_id;
1706            let buffer_id = anchor.buffer_id;
1707            let excerpt_anchors = iter::from_fn(|| {
1708                let anchor = anchors.peek()?;
1709                if anchor.excerpt_id == *excerpt_id && anchor.buffer_id == buffer_id {
1710                    Some(&anchors.next().unwrap().text_anchor)
1711                } else {
1712                    None
1713                }
1714            });
1715
1716            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1717            if cursor.item().is_none() {
1718                cursor.next(&());
1719            }
1720
1721            let position = D::from_text_summary(&cursor.start().text);
1722            if let Some(excerpt) = cursor.item() {
1723                if excerpt.id == *excerpt_id && excerpt.buffer_id == buffer_id {
1724                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1725                    let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1726                    summaries.extend(
1727                        excerpt
1728                            .buffer
1729                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1730                            .map(move |summary| {
1731                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
1732                                let mut position = position.clone();
1733                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1734                                if summary > excerpt_buffer_start {
1735                                    position.add_assign(&(summary - excerpt_buffer_start));
1736                                }
1737                                position
1738                            }),
1739                    );
1740                    continue;
1741                }
1742            }
1743
1744            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1745        }
1746
1747        summaries
1748    }
1749
1750    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1751    where
1752        I: 'a + IntoIterator<Item = &'a Anchor>,
1753    {
1754        let mut anchors = anchors.into_iter().enumerate().peekable();
1755        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1756        let mut result = Vec::new();
1757        while let Some((_, anchor)) = anchors.peek() {
1758            let old_excerpt_id = &anchor.excerpt_id;
1759
1760            // Find the location where this anchor's excerpt should be.
1761            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1762            if cursor.item().is_none() {
1763                cursor.next(&());
1764            }
1765
1766            let next_excerpt = cursor.item();
1767            let prev_excerpt = cursor.prev_item();
1768
1769            // Process all of the anchors for this excerpt.
1770            while let Some((_, anchor)) = anchors.peek() {
1771                if anchor.excerpt_id != *old_excerpt_id {
1772                    break;
1773                }
1774                let mut kept_position = false;
1775                let (anchor_ix, anchor) = anchors.next().unwrap();
1776                let mut anchor = anchor.clone();
1777
1778                // Leave min and max anchors unchanged.
1779                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1780                    kept_position = true;
1781                }
1782                // If the old excerpt still exists at this location, then leave
1783                // the anchor unchanged.
1784                else if next_excerpt.map_or(false, |excerpt| {
1785                    excerpt.id == *old_excerpt_id && excerpt.contains(&anchor)
1786                }) {
1787                    kept_position = true;
1788                }
1789                // If the old excerpt no longer exists at this location, then attempt to
1790                // find an equivalent position for this anchor in an adjacent excerpt.
1791                else {
1792                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1793                        if excerpt.contains(&anchor) {
1794                            anchor.excerpt_id = excerpt.id.clone();
1795                            kept_position = true;
1796                            break;
1797                        }
1798                    }
1799                }
1800                // If there's no adjacent excerpt that contains the anchor's position,
1801                // then report that the anchor has lost its position.
1802                if !kept_position {
1803                    anchor = if let Some(excerpt) = next_excerpt {
1804                        let mut text_anchor = excerpt
1805                            .range
1806                            .start
1807                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1808                        if text_anchor
1809                            .cmp(&excerpt.range.end, &excerpt.buffer)
1810                            .unwrap()
1811                            .is_gt()
1812                        {
1813                            text_anchor = excerpt.range.end.clone();
1814                        }
1815                        Anchor {
1816                            buffer_id: excerpt.buffer_id,
1817                            excerpt_id: excerpt.id.clone(),
1818                            text_anchor,
1819                        }
1820                    } else if let Some(excerpt) = prev_excerpt {
1821                        let mut text_anchor = excerpt
1822                            .range
1823                            .end
1824                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1825                        if text_anchor
1826                            .cmp(&excerpt.range.start, &excerpt.buffer)
1827                            .unwrap()
1828                            .is_lt()
1829                        {
1830                            text_anchor = excerpt.range.start.clone();
1831                        }
1832                        Anchor {
1833                            buffer_id: excerpt.buffer_id,
1834                            excerpt_id: excerpt.id.clone(),
1835                            text_anchor,
1836                        }
1837                    } else if anchor.text_anchor.bias == Bias::Left {
1838                        Anchor::min()
1839                    } else {
1840                        Anchor::max()
1841                    };
1842                }
1843
1844                result.push((anchor_ix, anchor, kept_position));
1845            }
1846        }
1847        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self).unwrap());
1848        result
1849    }
1850
1851    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1852        self.anchor_at(position, Bias::Left)
1853    }
1854
1855    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1856        self.anchor_at(position, Bias::Right)
1857    }
1858
1859    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1860        let offset = position.to_offset(self);
1861        if let Some(excerpt) = self.as_singleton() {
1862            return Anchor {
1863                buffer_id: excerpt.buffer_id,
1864                excerpt_id: excerpt.id.clone(),
1865                text_anchor: excerpt.buffer.anchor_at(offset, bias),
1866            };
1867        }
1868
1869        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1870        cursor.seek(&offset, Bias::Right, &());
1871        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1872            cursor.prev(&());
1873        }
1874        if let Some(excerpt) = cursor.item() {
1875            let mut overshoot = offset.saturating_sub(cursor.start().0);
1876            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1877                overshoot -= 1;
1878                bias = Bias::Right;
1879            }
1880
1881            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1882            let text_anchor =
1883                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1884            Anchor {
1885                buffer_id: excerpt.buffer_id,
1886                excerpt_id: excerpt.id.clone(),
1887                text_anchor,
1888            }
1889        } else if offset == 0 && bias == Bias::Left {
1890            Anchor::min()
1891        } else {
1892            Anchor::max()
1893        }
1894    }
1895
1896    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1897        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1898        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1899        if let Some(excerpt) = cursor.item() {
1900            if excerpt.id == excerpt_id {
1901                let text_anchor = excerpt.clip_anchor(text_anchor);
1902                drop(cursor);
1903                return Anchor {
1904                    buffer_id: excerpt.buffer_id,
1905                    excerpt_id,
1906                    text_anchor,
1907                };
1908            }
1909        }
1910        panic!("excerpt not found");
1911    }
1912
1913    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
1914        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
1915            true
1916        } else if let Some((buffer_id, buffer_snapshot)) =
1917            self.buffer_snapshot_for_excerpt(&anchor.excerpt_id)
1918        {
1919            anchor.buffer_id == buffer_id && buffer_snapshot.can_resolve(&anchor.text_anchor)
1920        } else {
1921            false
1922        }
1923    }
1924
1925    pub fn excerpt_boundaries_in_range<'a, R, T>(
1926        &'a self,
1927        range: R,
1928    ) -> impl Iterator<Item = ExcerptBoundary> + 'a
1929    where
1930        R: RangeBounds<T>,
1931        T: ToOffset,
1932    {
1933        let start_offset;
1934        let start = match range.start_bound() {
1935            Bound::Included(start) => {
1936                start_offset = start.to_offset(self);
1937                Bound::Included(start_offset)
1938            }
1939            Bound::Excluded(start) => {
1940                start_offset = start.to_offset(self);
1941                Bound::Excluded(start_offset)
1942            }
1943            Bound::Unbounded => {
1944                start_offset = 0;
1945                Bound::Unbounded
1946            }
1947        };
1948        let end = match range.end_bound() {
1949            Bound::Included(end) => Bound::Included(end.to_offset(self)),
1950            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
1951            Bound::Unbounded => Bound::Unbounded,
1952        };
1953        let bounds = (start, end);
1954
1955        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1956        cursor.seek(&start_offset, Bias::Right, &());
1957        if cursor.item().is_none() {
1958            cursor.prev(&());
1959        }
1960        if !bounds.contains(&cursor.start().0) {
1961            cursor.next(&());
1962        }
1963
1964        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
1965        std::iter::from_fn(move || {
1966            if self.singleton {
1967                None
1968            } else if bounds.contains(&cursor.start().0) {
1969                let excerpt = cursor.item()?;
1970                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
1971                let boundary = ExcerptBoundary {
1972                    row: cursor.start().1.row,
1973                    buffer: excerpt.buffer.clone(),
1974                    range: excerpt.range.clone(),
1975                    starts_new_buffer,
1976                };
1977
1978                prev_buffer_id = Some(excerpt.buffer_id);
1979                cursor.next(&());
1980                Some(boundary)
1981            } else {
1982                None
1983            }
1984        })
1985    }
1986
1987    pub fn parse_count(&self) -> usize {
1988        self.parse_count
1989    }
1990
1991    pub fn enclosing_bracket_ranges<T: ToOffset>(
1992        &self,
1993        range: Range<T>,
1994    ) -> Option<(Range<usize>, Range<usize>)> {
1995        let range = range.start.to_offset(self)..range.end.to_offset(self);
1996
1997        let mut cursor = self.excerpts.cursor::<usize>();
1998        cursor.seek(&range.start, Bias::Right, &());
1999        let start_excerpt = cursor.item();
2000
2001        cursor.seek(&range.end, Bias::Right, &());
2002        let end_excerpt = cursor.item();
2003
2004        start_excerpt
2005            .zip(end_excerpt)
2006            .and_then(|(start_excerpt, end_excerpt)| {
2007                if start_excerpt.id != end_excerpt.id {
2008                    return None;
2009                }
2010
2011                let excerpt_buffer_start =
2012                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2013                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2014
2015                let start_in_buffer =
2016                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2017                let end_in_buffer =
2018                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2019                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
2020                    .buffer
2021                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
2022
2023                if start_bracket_range.start >= excerpt_buffer_start
2024                    && end_bracket_range.end < excerpt_buffer_end
2025                {
2026                    start_bracket_range.start =
2027                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
2028                    start_bracket_range.end =
2029                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
2030                    end_bracket_range.start =
2031                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
2032                    end_bracket_range.end =
2033                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
2034                    Some((start_bracket_range, end_bracket_range))
2035                } else {
2036                    None
2037                }
2038            })
2039    }
2040
2041    pub fn diagnostics_update_count(&self) -> usize {
2042        self.diagnostics_update_count
2043    }
2044
2045    pub fn trailing_excerpt_update_count(&self) -> usize {
2046        self.trailing_excerpt_update_count
2047    }
2048
2049    pub fn language(&self) -> Option<&Arc<Language>> {
2050        self.excerpts
2051            .iter()
2052            .next()
2053            .and_then(|excerpt| excerpt.buffer.language())
2054    }
2055
2056    pub fn is_dirty(&self) -> bool {
2057        self.is_dirty
2058    }
2059
2060    pub fn has_conflict(&self) -> bool {
2061        self.has_conflict
2062    }
2063
2064    pub fn diagnostic_group<'a, O>(
2065        &'a self,
2066        group_id: usize,
2067    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2068    where
2069        O: text::FromAnchor + 'a,
2070    {
2071        self.as_singleton()
2072            .into_iter()
2073            .flat_map(move |excerpt| excerpt.buffer.diagnostic_group(group_id))
2074    }
2075
2076    pub fn diagnostics_in_range<'a, T, O>(
2077        &'a self,
2078        range: Range<T>,
2079    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2080    where
2081        T: 'a + ToOffset,
2082        O: 'a + text::FromAnchor,
2083    {
2084        self.as_singleton().into_iter().flat_map(move |excerpt| {
2085            excerpt
2086                .buffer
2087                .diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
2088        })
2089    }
2090
2091    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2092        let range = range.start.to_offset(self)..range.end.to_offset(self);
2093
2094        let mut cursor = self.excerpts.cursor::<usize>();
2095        cursor.seek(&range.start, Bias::Right, &());
2096        let start_excerpt = cursor.item();
2097
2098        cursor.seek(&range.end, Bias::Right, &());
2099        let end_excerpt = cursor.item();
2100
2101        start_excerpt
2102            .zip(end_excerpt)
2103            .and_then(|(start_excerpt, end_excerpt)| {
2104                if start_excerpt.id != end_excerpt.id {
2105                    return None;
2106                }
2107
2108                let excerpt_buffer_start =
2109                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2110                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2111
2112                let start_in_buffer =
2113                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2114                let end_in_buffer =
2115                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2116                let mut ancestor_buffer_range = start_excerpt
2117                    .buffer
2118                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2119                ancestor_buffer_range.start =
2120                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2121                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2122
2123                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
2124                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
2125                Some(start..end)
2126            })
2127    }
2128
2129    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2130        let excerpt = self.as_singleton()?;
2131        let outline = excerpt.buffer.outline(theme)?;
2132        Some(Outline::new(
2133            outline
2134                .items
2135                .into_iter()
2136                .map(|item| OutlineItem {
2137                    depth: item.depth,
2138                    range: self.anchor_in_excerpt(excerpt.id.clone(), item.range.start)
2139                        ..self.anchor_in_excerpt(excerpt.id.clone(), item.range.end),
2140                    text: item.text,
2141                    highlight_ranges: item.highlight_ranges,
2142                    name_ranges: item.name_ranges,
2143                })
2144                .collect(),
2145        ))
2146    }
2147
2148    fn buffer_snapshot_for_excerpt<'a>(
2149        &'a self,
2150        excerpt_id: &'a ExcerptId,
2151    ) -> Option<(usize, &'a BufferSnapshot)> {
2152        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2153        cursor.seek(&Some(excerpt_id), Bias::Left, &());
2154        if let Some(excerpt) = cursor.item() {
2155            if excerpt.id == *excerpt_id {
2156                return Some((excerpt.buffer_id, &excerpt.buffer));
2157            }
2158        }
2159        None
2160    }
2161
2162    pub fn remote_selections_in_range<'a>(
2163        &'a self,
2164        range: &'a Range<Anchor>,
2165    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
2166        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2167        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
2168        cursor
2169            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
2170            .flat_map(move |excerpt| {
2171                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
2172                if excerpt.id == range.start.excerpt_id {
2173                    query_range.start = range.start.text_anchor.clone();
2174                }
2175                if excerpt.id == range.end.excerpt_id {
2176                    query_range.end = range.end.text_anchor.clone();
2177                }
2178
2179                excerpt
2180                    .buffer
2181                    .remote_selections_in_range(query_range)
2182                    .flat_map(move |(replica_id, selections)| {
2183                        selections.map(move |selection| {
2184                            let mut start = Anchor {
2185                                buffer_id: excerpt.buffer_id,
2186                                excerpt_id: excerpt.id.clone(),
2187                                text_anchor: selection.start.clone(),
2188                            };
2189                            let mut end = Anchor {
2190                                buffer_id: excerpt.buffer_id,
2191                                excerpt_id: excerpt.id.clone(),
2192                                text_anchor: selection.end.clone(),
2193                            };
2194                            if range.start.cmp(&start, self).unwrap().is_gt() {
2195                                start = range.start.clone();
2196                            }
2197                            if range.end.cmp(&end, self).unwrap().is_lt() {
2198                                end = range.end.clone();
2199                            }
2200
2201                            (
2202                                replica_id,
2203                                Selection {
2204                                    id: selection.id,
2205                                    start,
2206                                    end,
2207                                    reversed: selection.reversed,
2208                                    goal: selection.goal,
2209                                },
2210                            )
2211                        })
2212                    })
2213            })
2214    }
2215}
2216
2217impl History {
2218    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
2219        self.transaction_depth += 1;
2220        if self.transaction_depth == 1 {
2221            let id = self.next_transaction_id.tick();
2222            self.undo_stack.push(Transaction {
2223                id,
2224                buffer_transactions: Default::default(),
2225                first_edit_at: now,
2226                last_edit_at: now,
2227                suppress_grouping: false,
2228            });
2229            Some(id)
2230        } else {
2231            None
2232        }
2233    }
2234
2235    fn end_transaction(
2236        &mut self,
2237        now: Instant,
2238        buffer_transactions: HashMap<usize, TransactionId>,
2239    ) -> bool {
2240        assert_ne!(self.transaction_depth, 0);
2241        self.transaction_depth -= 1;
2242        if self.transaction_depth == 0 {
2243            if buffer_transactions.is_empty() {
2244                self.undo_stack.pop();
2245                false
2246            } else {
2247                let transaction = self.undo_stack.last_mut().unwrap();
2248                transaction.last_edit_at = now;
2249                for (buffer_id, transaction_id) in buffer_transactions {
2250                    transaction
2251                        .buffer_transactions
2252                        .entry(buffer_id)
2253                        .or_insert(transaction_id);
2254                }
2255                true
2256            }
2257        } else {
2258            false
2259        }
2260    }
2261
2262    fn push_transaction<'a, T>(&mut self, buffer_transactions: T, now: Instant)
2263    where
2264        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
2265    {
2266        assert_eq!(self.transaction_depth, 0);
2267        self.undo_stack.push(Transaction {
2268            id: self.next_transaction_id.tick(),
2269            buffer_transactions: buffer_transactions
2270                .into_iter()
2271                .map(|(buffer, transaction)| (buffer.id(), transaction.id))
2272                .collect(),
2273            first_edit_at: now,
2274            last_edit_at: now,
2275            suppress_grouping: false,
2276        });
2277    }
2278
2279    fn finalize_last_transaction(&mut self) {
2280        if let Some(transaction) = self.undo_stack.last_mut() {
2281            transaction.suppress_grouping = true;
2282        }
2283    }
2284
2285    fn pop_undo(&mut self) -> Option<&mut Transaction> {
2286        assert_eq!(self.transaction_depth, 0);
2287        if let Some(transaction) = self.undo_stack.pop() {
2288            self.redo_stack.push(transaction);
2289            self.redo_stack.last_mut()
2290        } else {
2291            None
2292        }
2293    }
2294
2295    fn pop_redo(&mut self) -> Option<&mut Transaction> {
2296        assert_eq!(self.transaction_depth, 0);
2297        if let Some(transaction) = self.redo_stack.pop() {
2298            self.undo_stack.push(transaction);
2299            self.undo_stack.last_mut()
2300        } else {
2301            None
2302        }
2303    }
2304
2305    fn group(&mut self) -> Option<TransactionId> {
2306        let mut new_len = self.undo_stack.len();
2307        let mut transactions = self.undo_stack.iter_mut();
2308
2309        if let Some(mut transaction) = transactions.next_back() {
2310            while let Some(prev_transaction) = transactions.next_back() {
2311                if !prev_transaction.suppress_grouping
2312                    && transaction.first_edit_at - prev_transaction.last_edit_at
2313                        <= self.group_interval
2314                {
2315                    transaction = prev_transaction;
2316                    new_len -= 1;
2317                } else {
2318                    break;
2319                }
2320            }
2321        }
2322
2323        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
2324        if let Some(last_transaction) = transactions_to_keep.last_mut() {
2325            if let Some(transaction) = transactions_to_merge.last() {
2326                last_transaction.last_edit_at = transaction.last_edit_at;
2327            }
2328            for to_merge in transactions_to_merge {
2329                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
2330                    last_transaction
2331                        .buffer_transactions
2332                        .entry(*buffer_id)
2333                        .or_insert(*transaction_id);
2334                }
2335            }
2336        }
2337
2338        self.undo_stack.truncate(new_len);
2339        self.undo_stack.last().map(|t| t.id)
2340    }
2341}
2342
2343impl Excerpt {
2344    fn new(
2345        id: ExcerptId,
2346        buffer_id: usize,
2347        buffer: BufferSnapshot,
2348        range: Range<text::Anchor>,
2349        has_trailing_newline: bool,
2350    ) -> Self {
2351        Excerpt {
2352            id,
2353            max_buffer_row: range.end.to_point(&buffer).row,
2354            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
2355            buffer_id,
2356            buffer,
2357            range,
2358            has_trailing_newline,
2359        }
2360    }
2361
2362    fn chunks_in_range<'a>(
2363        &'a self,
2364        range: Range<usize>,
2365        language_aware: bool,
2366    ) -> ExcerptChunks<'a> {
2367        let content_start = self.range.start.to_offset(&self.buffer);
2368        let chunks_start = content_start + range.start;
2369        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2370
2371        let footer_height = if self.has_trailing_newline
2372            && range.start <= self.text_summary.bytes
2373            && range.end > self.text_summary.bytes
2374        {
2375            1
2376        } else {
2377            0
2378        };
2379
2380        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
2381
2382        ExcerptChunks {
2383            content_chunks,
2384            footer_height,
2385        }
2386    }
2387
2388    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
2389        let content_start = self.range.start.to_offset(&self.buffer);
2390        let bytes_start = content_start + range.start;
2391        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2392        let footer_height = if self.has_trailing_newline
2393            && range.start <= self.text_summary.bytes
2394            && range.end > self.text_summary.bytes
2395        {
2396            1
2397        } else {
2398            0
2399        };
2400        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
2401
2402        ExcerptBytes {
2403            content_bytes,
2404            footer_height,
2405        }
2406    }
2407
2408    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
2409        if text_anchor
2410            .cmp(&self.range.start, &self.buffer)
2411            .unwrap()
2412            .is_lt()
2413        {
2414            self.range.start.clone()
2415        } else if text_anchor
2416            .cmp(&self.range.end, &self.buffer)
2417            .unwrap()
2418            .is_gt()
2419        {
2420            self.range.end.clone()
2421        } else {
2422            text_anchor
2423        }
2424    }
2425
2426    fn contains(&self, anchor: &Anchor) -> bool {
2427        self.buffer_id == anchor.buffer_id
2428            && self
2429                .range
2430                .start
2431                .cmp(&anchor.text_anchor, &self.buffer)
2432                .unwrap()
2433                .is_le()
2434            && self
2435                .range
2436                .end
2437                .cmp(&anchor.text_anchor, &self.buffer)
2438                .unwrap()
2439                .is_ge()
2440    }
2441}
2442
2443impl fmt::Debug for Excerpt {
2444    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2445        f.debug_struct("Excerpt")
2446            .field("id", &self.id)
2447            .field("buffer_id", &self.buffer_id)
2448            .field("range", &self.range)
2449            .field("text_summary", &self.text_summary)
2450            .field("has_trailing_newline", &self.has_trailing_newline)
2451            .finish()
2452    }
2453}
2454
2455impl sum_tree::Item for Excerpt {
2456    type Summary = ExcerptSummary;
2457
2458    fn summary(&self) -> Self::Summary {
2459        let mut text = self.text_summary.clone();
2460        if self.has_trailing_newline {
2461            text += TextSummary::from("\n");
2462        }
2463        ExcerptSummary {
2464            excerpt_id: self.id.clone(),
2465            max_buffer_row: self.max_buffer_row,
2466            text,
2467        }
2468    }
2469}
2470
2471impl sum_tree::Summary for ExcerptSummary {
2472    type Context = ();
2473
2474    fn add_summary(&mut self, summary: &Self, _: &()) {
2475        debug_assert!(summary.excerpt_id > self.excerpt_id);
2476        self.excerpt_id = summary.excerpt_id.clone();
2477        self.text.add_summary(&summary.text, &());
2478        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2479    }
2480}
2481
2482impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2483    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2484        *self += &summary.text;
2485    }
2486}
2487
2488impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2489    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2490        *self += summary.text.bytes;
2491    }
2492}
2493
2494impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2495    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2496        Ord::cmp(self, &cursor_location.text.bytes)
2497    }
2498}
2499
2500impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2501    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2502        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2503    }
2504}
2505
2506impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2507    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2508        *self += summary.text.lines;
2509    }
2510}
2511
2512impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2513    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2514        *self += summary.text.lines_utf16
2515    }
2516}
2517
2518impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2519    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2520        *self = Some(&summary.excerpt_id);
2521    }
2522}
2523
2524impl<'a> MultiBufferRows<'a> {
2525    pub fn seek(&mut self, row: u32) {
2526        self.buffer_row_range = 0..0;
2527
2528        self.excerpts
2529            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2530        if self.excerpts.item().is_none() {
2531            self.excerpts.prev(&());
2532
2533            if self.excerpts.item().is_none() && row == 0 {
2534                self.buffer_row_range = 0..1;
2535                return;
2536            }
2537        }
2538
2539        if let Some(excerpt) = self.excerpts.item() {
2540            let overshoot = row - self.excerpts.start().row;
2541            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2542            self.buffer_row_range.start = excerpt_start + overshoot;
2543            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2544        }
2545    }
2546}
2547
2548impl<'a> Iterator for MultiBufferRows<'a> {
2549    type Item = Option<u32>;
2550
2551    fn next(&mut self) -> Option<Self::Item> {
2552        loop {
2553            if !self.buffer_row_range.is_empty() {
2554                let row = Some(self.buffer_row_range.start);
2555                self.buffer_row_range.start += 1;
2556                return Some(row);
2557            }
2558            self.excerpts.item()?;
2559            self.excerpts.next(&());
2560            let excerpt = self.excerpts.item()?;
2561            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2562            self.buffer_row_range.end =
2563                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2564        }
2565    }
2566}
2567
2568impl<'a> MultiBufferChunks<'a> {
2569    pub fn offset(&self) -> usize {
2570        self.range.start
2571    }
2572
2573    pub fn seek(&mut self, offset: usize) {
2574        self.range.start = offset;
2575        self.excerpts.seek(&offset, Bias::Right, &());
2576        if let Some(excerpt) = self.excerpts.item() {
2577            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2578                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2579                self.language_aware,
2580            ));
2581        } else {
2582            self.excerpt_chunks = None;
2583        }
2584    }
2585}
2586
2587impl<'a> Iterator for MultiBufferChunks<'a> {
2588    type Item = Chunk<'a>;
2589
2590    fn next(&mut self) -> Option<Self::Item> {
2591        if self.range.is_empty() {
2592            None
2593        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2594            self.range.start += chunk.text.len();
2595            Some(chunk)
2596        } else {
2597            self.excerpts.next(&());
2598            let excerpt = self.excerpts.item()?;
2599            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2600                0..self.range.end - self.excerpts.start(),
2601                self.language_aware,
2602            ));
2603            self.next()
2604        }
2605    }
2606}
2607
2608impl<'a> MultiBufferBytes<'a> {
2609    fn consume(&mut self, len: usize) {
2610        self.range.start += len;
2611        self.chunk = &self.chunk[len..];
2612
2613        if !self.range.is_empty() && self.chunk.is_empty() {
2614            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2615                self.chunk = chunk;
2616            } else {
2617                self.excerpts.next(&());
2618                if let Some(excerpt) = self.excerpts.item() {
2619                    let mut excerpt_bytes =
2620                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2621                    self.chunk = excerpt_bytes.next().unwrap();
2622                    self.excerpt_bytes = Some(excerpt_bytes);
2623                }
2624            }
2625        }
2626    }
2627}
2628
2629impl<'a> Iterator for MultiBufferBytes<'a> {
2630    type Item = &'a [u8];
2631
2632    fn next(&mut self) -> Option<Self::Item> {
2633        let chunk = self.chunk;
2634        if chunk.is_empty() {
2635            None
2636        } else {
2637            self.consume(chunk.len());
2638            Some(chunk)
2639        }
2640    }
2641}
2642
2643impl<'a> io::Read for MultiBufferBytes<'a> {
2644    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2645        let len = cmp::min(buf.len(), self.chunk.len());
2646        buf[..len].copy_from_slice(&self.chunk[..len]);
2647        if len > 0 {
2648            self.consume(len);
2649        }
2650        Ok(len)
2651    }
2652}
2653
2654impl<'a> Iterator for ExcerptBytes<'a> {
2655    type Item = &'a [u8];
2656
2657    fn next(&mut self) -> Option<Self::Item> {
2658        if let Some(chunk) = self.content_bytes.next() {
2659            if !chunk.is_empty() {
2660                return Some(chunk);
2661            }
2662        }
2663
2664        if self.footer_height > 0 {
2665            let result = &NEWLINES[..self.footer_height];
2666            self.footer_height = 0;
2667            return Some(result);
2668        }
2669
2670        None
2671    }
2672}
2673
2674impl<'a> Iterator for ExcerptChunks<'a> {
2675    type Item = Chunk<'a>;
2676
2677    fn next(&mut self) -> Option<Self::Item> {
2678        if let Some(chunk) = self.content_chunks.next() {
2679            return Some(chunk);
2680        }
2681
2682        if self.footer_height > 0 {
2683            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2684            self.footer_height = 0;
2685            return Some(Chunk {
2686                text,
2687                ..Default::default()
2688            });
2689        }
2690
2691        None
2692    }
2693}
2694
2695impl ToOffset for Point {
2696    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2697        snapshot.point_to_offset(*self)
2698    }
2699}
2700
2701impl ToOffset for PointUtf16 {
2702    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2703        snapshot.point_utf16_to_offset(*self)
2704    }
2705}
2706
2707impl ToOffset for usize {
2708    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2709        assert!(*self <= snapshot.len(), "offset is out of range");
2710        *self
2711    }
2712}
2713
2714impl ToPoint for usize {
2715    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2716        snapshot.offset_to_point(*self)
2717    }
2718}
2719
2720impl ToPoint for Point {
2721    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2722        *self
2723    }
2724}
2725
2726impl ToPointUtf16 for usize {
2727    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2728        snapshot.offset_to_point_utf16(*self)
2729    }
2730}
2731
2732impl ToPointUtf16 for Point {
2733    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2734        snapshot.point_to_point_utf16(*self)
2735    }
2736}
2737
2738impl ToPointUtf16 for PointUtf16 {
2739    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
2740        *self
2741    }
2742}
2743
2744pub fn char_kind(c: char) -> CharKind {
2745    if c == '\n' {
2746        CharKind::Newline
2747    } else if c.is_whitespace() {
2748        CharKind::Whitespace
2749    } else if c.is_alphanumeric() || c == '_' {
2750        CharKind::Word
2751    } else {
2752        CharKind::Punctuation
2753    }
2754}
2755
2756#[cfg(test)]
2757mod tests {
2758    use super::*;
2759    use gpui::MutableAppContext;
2760    use language::{Buffer, Rope};
2761    use rand::prelude::*;
2762    use std::env;
2763    use text::{Point, RandomCharIter};
2764    use util::test::sample_text;
2765
2766    #[gpui::test]
2767    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2768        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2769        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2770
2771        let snapshot = multibuffer.read(cx).snapshot(cx);
2772        assert_eq!(snapshot.text(), buffer.read(cx).text());
2773
2774        assert_eq!(
2775            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2776            (0..buffer.read(cx).row_count())
2777                .map(Some)
2778                .collect::<Vec<_>>()
2779        );
2780
2781        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2782        let snapshot = multibuffer.read(cx).snapshot(cx);
2783
2784        assert_eq!(snapshot.text(), buffer.read(cx).text());
2785        assert_eq!(
2786            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2787            (0..buffer.read(cx).row_count())
2788                .map(Some)
2789                .collect::<Vec<_>>()
2790        );
2791    }
2792
2793    #[gpui::test]
2794    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2795        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2796        let guest_buffer = cx.add_model(|cx| {
2797            let message = host_buffer.read(cx).to_proto();
2798            Buffer::from_proto(1, message, None, cx).unwrap()
2799        });
2800        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2801        let snapshot = multibuffer.read(cx).snapshot(cx);
2802        assert_eq!(snapshot.text(), "a");
2803
2804        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2805        let snapshot = multibuffer.read(cx).snapshot(cx);
2806        assert_eq!(snapshot.text(), "ab");
2807
2808        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2809        let snapshot = multibuffer.read(cx).snapshot(cx);
2810        assert_eq!(snapshot.text(), "abc");
2811    }
2812
2813    #[gpui::test]
2814    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2815        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2816        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2817        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2818
2819        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2820            let subscription = multibuffer.subscribe();
2821            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(1, 2)..Point::new(2, 5)], cx);
2822            assert_eq!(
2823                subscription.consume().into_inner(),
2824                [Edit {
2825                    old: 0..0,
2826                    new: 0..10
2827                }]
2828            );
2829
2830            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(3, 3)..Point::new(4, 4)], cx);
2831            multibuffer.push_excerpts(buffer_2.clone(), [Point::new(3, 1)..Point::new(3, 3)], cx);
2832            assert_eq!(
2833                subscription.consume().into_inner(),
2834                [Edit {
2835                    old: 10..10,
2836                    new: 10..22
2837                }]
2838            );
2839
2840            subscription
2841        });
2842
2843        let snapshot = multibuffer.read(cx).snapshot(cx);
2844        assert_eq!(
2845            snapshot.text(),
2846            concat!(
2847                "bbbb\n",  // Preserve newlines
2848                "ccccc\n", //
2849                "ddd\n",   //
2850                "eeee\n",  //
2851                "jj"       //
2852            )
2853        );
2854        assert_eq!(
2855            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2856            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2857        );
2858        assert_eq!(
2859            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2860            [Some(3), Some(4), Some(3)]
2861        );
2862        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2863        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2864
2865        assert_eq!(
2866            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
2867            &[
2868                (0, "bbbb\nccccc".to_string(), true),
2869                (2, "ddd\neeee".to_string(), false),
2870                (4, "jj".to_string(), true),
2871            ]
2872        );
2873        assert_eq!(
2874            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
2875            &[(0, "bbbb\nccccc".to_string(), true)]
2876        );
2877        assert_eq!(
2878            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
2879            &[]
2880        );
2881        assert_eq!(
2882            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
2883            &[]
2884        );
2885        assert_eq!(
2886            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2887            &[(2, "ddd\neeee".to_string(), false)]
2888        );
2889        assert_eq!(
2890            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2891            &[(2, "ddd\neeee".to_string(), false)]
2892        );
2893        assert_eq!(
2894            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
2895            &[(2, "ddd\neeee".to_string(), false)]
2896        );
2897        assert_eq!(
2898            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
2899            &[(4, "jj".to_string(), true)]
2900        );
2901        assert_eq!(
2902            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
2903            &[]
2904        );
2905
2906        buffer_1.update(cx, |buffer, cx| {
2907            buffer.edit(
2908                [
2909                    Point::new(0, 0)..Point::new(0, 0),
2910                    Point::new(2, 1)..Point::new(2, 3),
2911                ],
2912                "\n",
2913                cx,
2914            );
2915        });
2916
2917        let snapshot = multibuffer.read(cx).snapshot(cx);
2918        assert_eq!(
2919            snapshot.text(),
2920            concat!(
2921                "bbbb\n", // Preserve newlines
2922                "c\n",    //
2923                "cc\n",   //
2924                "ddd\n",  //
2925                "eeee\n", //
2926                "jj"      //
2927            )
2928        );
2929
2930        assert_eq!(
2931            subscription.consume().into_inner(),
2932            [Edit {
2933                old: 6..8,
2934                new: 6..7
2935            }]
2936        );
2937
2938        let snapshot = multibuffer.read(cx).snapshot(cx);
2939        assert_eq!(
2940            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2941            Point::new(0, 4)
2942        );
2943        assert_eq!(
2944            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2945            Point::new(0, 4)
2946        );
2947        assert_eq!(
2948            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2949            Point::new(5, 1)
2950        );
2951        assert_eq!(
2952            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2953            Point::new(5, 2)
2954        );
2955        assert_eq!(
2956            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2957            Point::new(5, 2)
2958        );
2959
2960        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2961            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2962            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2963            multibuffer.snapshot(cx)
2964        });
2965
2966        assert_eq!(
2967            snapshot.text(),
2968            concat!(
2969                "bbbb\n", // Preserve newlines
2970                "c\n",    //
2971                "cc\n",   //
2972                "ddd\n",  //
2973                "eeee",   //
2974            )
2975        );
2976
2977        fn boundaries_in_range(
2978            range: Range<Point>,
2979            snapshot: &MultiBufferSnapshot,
2980        ) -> Vec<(u32, String, bool)> {
2981            snapshot
2982                .excerpt_boundaries_in_range(range)
2983                .map(|boundary| {
2984                    (
2985                        boundary.row,
2986                        boundary
2987                            .buffer
2988                            .text_for_range(boundary.range)
2989                            .collect::<String>(),
2990                        boundary.starts_new_buffer,
2991                    )
2992                })
2993                .collect::<Vec<_>>()
2994        }
2995    }
2996
2997    #[gpui::test]
2998    fn test_excerpts_with_context_lines(cx: &mut MutableAppContext) {
2999        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
3000        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3001        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
3002            multibuffer.push_excerpts_with_context_lines(
3003                buffer.clone(),
3004                vec![
3005                    Point::new(3, 2)..Point::new(4, 2),
3006                    Point::new(7, 1)..Point::new(7, 3),
3007                    Point::new(15, 0)..Point::new(15, 0),
3008                ],
3009                2,
3010                cx,
3011            )
3012        });
3013
3014        let snapshot = multibuffer.read(cx).snapshot(cx);
3015        assert_eq!(
3016            snapshot.text(),
3017            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
3018        );
3019
3020        assert_eq!(
3021            anchor_ranges
3022                .iter()
3023                .map(|range| range.to_point(&snapshot))
3024                .collect::<Vec<_>>(),
3025            vec![
3026                Point::new(2, 2)..Point::new(3, 2),
3027                Point::new(6, 1)..Point::new(6, 3),
3028                Point::new(12, 0)..Point::new(12, 0)
3029            ]
3030        );
3031    }
3032
3033    #[gpui::test]
3034    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
3035        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3036
3037        let snapshot = multibuffer.read(cx).snapshot(cx);
3038        assert_eq!(snapshot.text(), "");
3039        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
3040        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
3041    }
3042
3043    #[gpui::test]
3044    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
3045        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3046        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3047        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3048        buffer.update(cx, |buffer, cx| {
3049            buffer.edit([0..0], "X", cx);
3050            buffer.edit([5..5], "Y", cx);
3051        });
3052        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3053
3054        assert_eq!(old_snapshot.text(), "abcd");
3055        assert_eq!(new_snapshot.text(), "XabcdY");
3056
3057        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3058        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3059        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
3060        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
3061    }
3062
3063    #[gpui::test]
3064    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
3065        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3066        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
3067        let multibuffer = cx.add_model(|cx| {
3068            let mut multibuffer = MultiBuffer::new(0);
3069            multibuffer.push_excerpts(buffer_1.clone(), [0..4], cx);
3070            multibuffer.push_excerpts(buffer_2.clone(), [0..5], cx);
3071            multibuffer
3072        });
3073        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3074
3075        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
3076        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
3077        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3078        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3079        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3080        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3081
3082        buffer_1.update(cx, |buffer, cx| {
3083            buffer.edit([0..0], "W", cx);
3084            buffer.edit([5..5], "X", cx);
3085        });
3086        buffer_2.update(cx, |buffer, cx| {
3087            buffer.edit([0..0], "Y", cx);
3088            buffer.edit([6..0], "Z", cx);
3089        });
3090        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3091
3092        assert_eq!(old_snapshot.text(), "abcd\nefghi");
3093        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
3094
3095        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3096        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3097        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
3098        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
3099        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
3100        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
3101        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
3102        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
3103        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
3104        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
3105    }
3106
3107    #[gpui::test]
3108    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
3109        cx: &mut MutableAppContext,
3110    ) {
3111        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3112        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
3113        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3114
3115        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
3116        // Add an excerpt from buffer 1 that spans this new insertion.
3117        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
3118        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
3119            multibuffer
3120                .push_excerpts(buffer_1.clone(), [0..7], cx)
3121                .pop()
3122                .unwrap()
3123        });
3124
3125        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
3126        assert_eq!(snapshot_1.text(), "abcd123");
3127
3128        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
3129        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
3130            multibuffer.remove_excerpts([&excerpt_id_1], cx);
3131            let mut ids = multibuffer
3132                .push_excerpts(buffer_2.clone(), [0..4, 6..10, 12..16], cx)
3133                .into_iter();
3134            (ids.next().unwrap(), ids.next().unwrap())
3135        });
3136        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
3137        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
3138
3139        // The old excerpt id has been reused.
3140        assert_eq!(excerpt_id_2, excerpt_id_1);
3141
3142        // Resolve some anchors from the previous snapshot in the new snapshot.
3143        // Although there is still an excerpt with the same id, it is for
3144        // a different buffer, so we don't attempt to resolve the old text
3145        // anchor in the new buffer.
3146        assert_eq!(
3147            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
3148            0
3149        );
3150        assert_eq!(
3151            snapshot_2.summaries_for_anchors::<usize, _>(&[
3152                snapshot_1.anchor_before(2),
3153                snapshot_1.anchor_after(3)
3154            ]),
3155            vec![0, 0]
3156        );
3157        let refresh =
3158            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
3159        assert_eq!(
3160            refresh,
3161            &[
3162                (0, snapshot_2.anchor_before(0), false),
3163                (1, snapshot_2.anchor_after(0), false),
3164            ]
3165        );
3166
3167        // Replace the middle excerpt with a smaller excerpt in buffer 2,
3168        // that intersects the old excerpt.
3169        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
3170            multibuffer.remove_excerpts([&excerpt_id_3], cx);
3171            multibuffer
3172                .insert_excerpts_after(&excerpt_id_3, buffer_2.clone(), [5..8], cx)
3173                .pop()
3174                .unwrap()
3175        });
3176
3177        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
3178        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
3179        assert_ne!(excerpt_id_5, excerpt_id_3);
3180
3181        // Resolve some anchors from the previous snapshot in the new snapshot.
3182        // The anchor in the middle excerpt snaps to the beginning of the
3183        // excerpt, since it is not
3184        let anchors = [
3185            snapshot_2.anchor_before(0),
3186            snapshot_2.anchor_after(2),
3187            snapshot_2.anchor_after(6),
3188            snapshot_2.anchor_after(14),
3189        ];
3190        assert_eq!(
3191            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
3192            &[0, 2, 9, 13]
3193        );
3194
3195        let new_anchors = snapshot_3.refresh_anchors(&anchors);
3196        assert_eq!(
3197            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
3198            &[(0, true), (1, true), (2, true), (3, true)]
3199        );
3200        assert_eq!(
3201            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
3202            &[0, 2, 7, 13]
3203        );
3204    }
3205
3206    #[gpui::test(iterations = 100)]
3207    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
3208        let operations = env::var("OPERATIONS")
3209            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
3210            .unwrap_or(10);
3211
3212        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
3213        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3214        let mut excerpt_ids = Vec::new();
3215        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
3216        let mut anchors = Vec::new();
3217        let mut old_versions = Vec::new();
3218
3219        for _ in 0..operations {
3220            match rng.gen_range(0..100) {
3221                0..=19 if !buffers.is_empty() => {
3222                    let buffer = buffers.choose(&mut rng).unwrap();
3223                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
3224                }
3225                20..=29 if !expected_excerpts.is_empty() => {
3226                    let mut ids_to_remove = vec![];
3227                    for _ in 0..rng.gen_range(1..=3) {
3228                        if expected_excerpts.is_empty() {
3229                            break;
3230                        }
3231
3232                        let ix = rng.gen_range(0..expected_excerpts.len());
3233                        ids_to_remove.push(excerpt_ids.remove(ix));
3234                        let (buffer, range) = expected_excerpts.remove(ix);
3235                        let buffer = buffer.read(cx);
3236                        log::info!(
3237                            "Removing excerpt {}: {:?}",
3238                            ix,
3239                            buffer
3240                                .text_for_range(range.to_offset(&buffer))
3241                                .collect::<String>(),
3242                        );
3243                    }
3244                    ids_to_remove.sort_unstable();
3245                    multibuffer.update(cx, |multibuffer, cx| {
3246                        multibuffer.remove_excerpts(&ids_to_remove, cx)
3247                    });
3248                }
3249                30..=39 if !expected_excerpts.is_empty() => {
3250                    let multibuffer = multibuffer.read(cx).read(cx);
3251                    let offset =
3252                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
3253                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
3254                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
3255                    anchors.push(multibuffer.anchor_at(offset, bias));
3256                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
3257                }
3258                40..=44 if !anchors.is_empty() => {
3259                    let multibuffer = multibuffer.read(cx).read(cx);
3260
3261                    anchors = multibuffer
3262                        .refresh_anchors(&anchors)
3263                        .into_iter()
3264                        .map(|a| a.1)
3265                        .collect();
3266
3267                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
3268                    // overshoot its boundaries.
3269                    let mut cursor = multibuffer.excerpts.cursor::<Option<&ExcerptId>>();
3270                    for anchor in &anchors {
3271                        if anchor.excerpt_id == ExcerptId::min()
3272                            || anchor.excerpt_id == ExcerptId::max()
3273                        {
3274                            continue;
3275                        }
3276
3277                        cursor.seek_forward(&Some(&anchor.excerpt_id), Bias::Left, &());
3278                        let excerpt = cursor.item().unwrap();
3279                        assert_eq!(excerpt.id, anchor.excerpt_id);
3280                        assert!(excerpt.contains(anchor));
3281                    }
3282                }
3283                _ => {
3284                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
3285                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
3286                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
3287                        buffers.last().unwrap()
3288                    } else {
3289                        buffers.choose(&mut rng).unwrap()
3290                    };
3291
3292                    let buffer = buffer_handle.read(cx);
3293                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3294                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3295                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3296                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
3297                    let prev_excerpt_id = excerpt_ids
3298                        .get(prev_excerpt_ix)
3299                        .cloned()
3300                        .unwrap_or(ExcerptId::max());
3301                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
3302
3303                    log::info!(
3304                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
3305                        excerpt_ix,
3306                        expected_excerpts.len(),
3307                        buffer_handle.id(),
3308                        buffer.text(),
3309                        start_ix..end_ix,
3310                        &buffer.text()[start_ix..end_ix]
3311                    );
3312
3313                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3314                        multibuffer
3315                            .insert_excerpts_after(
3316                                &prev_excerpt_id,
3317                                buffer_handle.clone(),
3318                                [start_ix..end_ix],
3319                                cx,
3320                            )
3321                            .pop()
3322                            .unwrap()
3323                    });
3324
3325                    excerpt_ids.insert(excerpt_ix, excerpt_id);
3326                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
3327                }
3328            }
3329
3330            if rng.gen_bool(0.3) {
3331                multibuffer.update(cx, |multibuffer, cx| {
3332                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
3333                })
3334            }
3335
3336            let snapshot = multibuffer.read(cx).snapshot(cx);
3337
3338            let mut excerpt_starts = Vec::new();
3339            let mut expected_text = String::new();
3340            let mut expected_buffer_rows = Vec::new();
3341            for (buffer, range) in &expected_excerpts {
3342                let buffer = buffer.read(cx);
3343                let buffer_range = range.to_offset(buffer);
3344
3345                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
3346                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
3347                expected_text.push('\n');
3348
3349                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
3350                    ..=buffer.offset_to_point(buffer_range.end).row;
3351                for row in buffer_row_range {
3352                    expected_buffer_rows.push(Some(row));
3353                }
3354            }
3355            // Remove final trailing newline.
3356            if !expected_excerpts.is_empty() {
3357                expected_text.pop();
3358            }
3359
3360            // Always report one buffer row
3361            if expected_buffer_rows.is_empty() {
3362                expected_buffer_rows.push(Some(0));
3363            }
3364
3365            assert_eq!(snapshot.text(), expected_text);
3366            log::info!("MultiBuffer text: {:?}", expected_text);
3367
3368            assert_eq!(
3369                snapshot.buffer_rows(0).collect::<Vec<_>>(),
3370                expected_buffer_rows,
3371            );
3372
3373            for _ in 0..5 {
3374                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
3375                assert_eq!(
3376                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
3377                    &expected_buffer_rows[start_row..],
3378                    "buffer_rows({})",
3379                    start_row
3380                );
3381            }
3382
3383            assert_eq!(
3384                snapshot.max_buffer_row(),
3385                expected_buffer_rows
3386                    .into_iter()
3387                    .filter_map(|r| r)
3388                    .max()
3389                    .unwrap()
3390            );
3391
3392            let mut excerpt_starts = excerpt_starts.into_iter();
3393            for (buffer, range) in &expected_excerpts {
3394                let buffer_id = buffer.id();
3395                let buffer = buffer.read(cx);
3396                let buffer_range = range.to_offset(buffer);
3397                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
3398                let buffer_start_point_utf16 =
3399                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
3400
3401                let excerpt_start = excerpt_starts.next().unwrap();
3402                let mut offset = excerpt_start.bytes;
3403                let mut buffer_offset = buffer_range.start;
3404                let mut point = excerpt_start.lines;
3405                let mut buffer_point = buffer_start_point;
3406                let mut point_utf16 = excerpt_start.lines_utf16;
3407                let mut buffer_point_utf16 = buffer_start_point_utf16;
3408                for ch in buffer
3409                    .snapshot()
3410                    .chunks(buffer_range.clone(), false)
3411                    .flat_map(|c| c.text.chars())
3412                {
3413                    for _ in 0..ch.len_utf8() {
3414                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
3415                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
3416                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
3417                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
3418                        assert_eq!(
3419                            left_offset,
3420                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
3421                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
3422                            offset,
3423                            buffer_id,
3424                            buffer_offset,
3425                        );
3426                        assert_eq!(
3427                            right_offset,
3428                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
3429                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
3430                            offset,
3431                            buffer_id,
3432                            buffer_offset,
3433                        );
3434
3435                        let left_point = snapshot.clip_point(point, Bias::Left);
3436                        let right_point = snapshot.clip_point(point, Bias::Right);
3437                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
3438                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
3439                        assert_eq!(
3440                            left_point,
3441                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
3442                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
3443                            point,
3444                            buffer_id,
3445                            buffer_point,
3446                        );
3447                        assert_eq!(
3448                            right_point,
3449                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
3450                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
3451                            point,
3452                            buffer_id,
3453                            buffer_point,
3454                        );
3455
3456                        assert_eq!(
3457                            snapshot.point_to_offset(left_point),
3458                            left_offset,
3459                            "point_to_offset({:?})",
3460                            left_point,
3461                        );
3462                        assert_eq!(
3463                            snapshot.offset_to_point(left_offset),
3464                            left_point,
3465                            "offset_to_point({:?})",
3466                            left_offset,
3467                        );
3468
3469                        offset += 1;
3470                        buffer_offset += 1;
3471                        if ch == '\n' {
3472                            point += Point::new(1, 0);
3473                            buffer_point += Point::new(1, 0);
3474                        } else {
3475                            point += Point::new(0, 1);
3476                            buffer_point += Point::new(0, 1);
3477                        }
3478                    }
3479
3480                    for _ in 0..ch.len_utf16() {
3481                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
3482                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
3483                        let buffer_left_point_utf16 =
3484                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
3485                        let buffer_right_point_utf16 =
3486                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
3487                        assert_eq!(
3488                            left_point_utf16,
3489                            excerpt_start.lines_utf16
3490                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
3491                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
3492                            point_utf16,
3493                            buffer_id,
3494                            buffer_point_utf16,
3495                        );
3496                        assert_eq!(
3497                            right_point_utf16,
3498                            excerpt_start.lines_utf16
3499                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
3500                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
3501                            point_utf16,
3502                            buffer_id,
3503                            buffer_point_utf16,
3504                        );
3505
3506                        if ch == '\n' {
3507                            point_utf16 += PointUtf16::new(1, 0);
3508                            buffer_point_utf16 += PointUtf16::new(1, 0);
3509                        } else {
3510                            point_utf16 += PointUtf16::new(0, 1);
3511                            buffer_point_utf16 += PointUtf16::new(0, 1);
3512                        }
3513                    }
3514                }
3515            }
3516
3517            for (row, line) in expected_text.split('\n').enumerate() {
3518                assert_eq!(
3519                    snapshot.line_len(row as u32),
3520                    line.len() as u32,
3521                    "line_len({}).",
3522                    row
3523                );
3524            }
3525
3526            let text_rope = Rope::from(expected_text.as_str());
3527            for _ in 0..10 {
3528                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3529                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3530
3531                let text_for_range = snapshot
3532                    .text_for_range(start_ix..end_ix)
3533                    .collect::<String>();
3534                assert_eq!(
3535                    text_for_range,
3536                    &expected_text[start_ix..end_ix],
3537                    "incorrect text for range {:?}",
3538                    start_ix..end_ix
3539                );
3540
3541                let excerpted_buffer_ranges =
3542                    multibuffer.read(cx).excerpted_buffers(start_ix..end_ix, cx);
3543                let excerpted_buffers_text = excerpted_buffer_ranges
3544                    .into_iter()
3545                    .map(|(buffer, buffer_range)| {
3546                        buffer
3547                            .read(cx)
3548                            .text_for_range(buffer_range)
3549                            .collect::<String>()
3550                    })
3551                    .collect::<Vec<_>>()
3552                    .join("\n");
3553                assert_eq!(excerpted_buffers_text, text_for_range);
3554
3555                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3556                assert_eq!(
3557                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3558                    expected_summary,
3559                    "incorrect summary for range {:?}",
3560                    start_ix..end_ix
3561                );
3562            }
3563
3564            // Anchor resolution
3565            for (anchor, resolved_offset) in anchors
3566                .iter()
3567                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3568            {
3569                assert!(resolved_offset <= snapshot.len());
3570                assert_eq!(
3571                    snapshot.summary_for_anchor::<usize>(anchor),
3572                    resolved_offset
3573                );
3574            }
3575
3576            for _ in 0..10 {
3577                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3578                assert_eq!(
3579                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3580                    expected_text[..end_ix].chars().rev().collect::<String>(),
3581                );
3582            }
3583
3584            for _ in 0..10 {
3585                let end_ix = rng.gen_range(0..=text_rope.len());
3586                let start_ix = rng.gen_range(0..=end_ix);
3587                assert_eq!(
3588                    snapshot
3589                        .bytes_in_range(start_ix..end_ix)
3590                        .flatten()
3591                        .copied()
3592                        .collect::<Vec<_>>(),
3593                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3594                    "bytes_in_range({:?})",
3595                    start_ix..end_ix,
3596                );
3597            }
3598        }
3599
3600        let snapshot = multibuffer.read(cx).snapshot(cx);
3601        for (old_snapshot, subscription) in old_versions {
3602            let edits = subscription.consume().into_inner();
3603
3604            log::info!(
3605                "applying subscription edits to old text: {:?}: {:?}",
3606                old_snapshot.text(),
3607                edits,
3608            );
3609
3610            let mut text = old_snapshot.text();
3611            for edit in edits {
3612                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3613                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3614            }
3615            assert_eq!(text.to_string(), snapshot.text());
3616        }
3617    }
3618
3619    #[gpui::test]
3620    fn test_history(cx: &mut MutableAppContext) {
3621        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3622        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3623        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3624        let group_interval = multibuffer.read(cx).history.group_interval;
3625        multibuffer.update(cx, |multibuffer, cx| {
3626            multibuffer.push_excerpts(buffer_1.clone(), [0..buffer_1.read(cx).len()], cx);
3627            multibuffer.push_excerpts(buffer_2.clone(), [0..buffer_2.read(cx).len()], cx);
3628        });
3629
3630        let mut now = Instant::now();
3631
3632        multibuffer.update(cx, |multibuffer, cx| {
3633            multibuffer.start_transaction_at(now, cx);
3634            multibuffer.edit(
3635                [
3636                    Point::new(0, 0)..Point::new(0, 0),
3637                    Point::new(1, 0)..Point::new(1, 0),
3638                ],
3639                "A",
3640                cx,
3641            );
3642            multibuffer.edit(
3643                [
3644                    Point::new(0, 1)..Point::new(0, 1),
3645                    Point::new(1, 1)..Point::new(1, 1),
3646                ],
3647                "B",
3648                cx,
3649            );
3650            multibuffer.end_transaction_at(now, cx);
3651            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3652
3653            now += 2 * group_interval;
3654            multibuffer.start_transaction_at(now, cx);
3655            multibuffer.edit([2..2], "C", cx);
3656            multibuffer.end_transaction_at(now, cx);
3657            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3658
3659            multibuffer.undo(cx);
3660            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3661
3662            multibuffer.undo(cx);
3663            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3664
3665            multibuffer.redo(cx);
3666            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3667
3668            multibuffer.redo(cx);
3669            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3670
3671            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3672            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3673
3674            multibuffer.undo(cx);
3675            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3676
3677            multibuffer.redo(cx);
3678            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3679
3680            multibuffer.redo(cx);
3681            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3682
3683            multibuffer.undo(cx);
3684            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3685
3686            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3687            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3688
3689            multibuffer.undo(cx);
3690            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3691        });
3692    }
3693}