multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::{Bound, HashMap, HashSet};
   7use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
   8pub use language::Completion;
   9use language::{
  10    Buffer, BufferChunks, BufferSnapshot, Chunk, DiagnosticEntry, Event, File, Language, Outline,
  11    OutlineItem, Selection, ToOffset as _, ToPoint as _, ToPointUtf16 as _, TransactionId,
  12};
  13use std::{
  14    cell::{Ref, RefCell},
  15    cmp, fmt, io,
  16    iter::{self, FromIterator},
  17    ops::{Range, RangeBounds, Sub},
  18    str,
  19    sync::Arc,
  20    time::{Duration, Instant},
  21};
  22use sum_tree::{Bias, Cursor, SumTree};
  23use text::{
  24    locator::Locator,
  25    rope::TextDimension,
  26    subscription::{Subscription, Topic},
  27    AnchorRangeExt as _, Edit, Point, PointUtf16, TextSummary,
  28};
  29use theme::SyntaxTheme;
  30
  31const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  32
  33pub type ExcerptId = Locator;
  34
  35pub struct MultiBuffer {
  36    snapshot: RefCell<MultiBufferSnapshot>,
  37    buffers: RefCell<HashMap<usize, BufferState>>,
  38    subscriptions: Topic,
  39    singleton: bool,
  40    replica_id: ReplicaId,
  41    history: History,
  42    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: Some(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: Some(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 excerpt_containing(
 783        &self,
 784        position: impl ToOffset,
 785        cx: &AppContext,
 786    ) -> Option<(ModelHandle<Buffer>, Range<text::Anchor>)> {
 787        let snapshot = self.read(cx);
 788        let position = position.to_offset(&snapshot);
 789
 790        let mut cursor = snapshot.excerpts.cursor::<usize>();
 791        cursor.seek(&position, Bias::Right, &());
 792        cursor.item().map(|excerpt| {
 793            (
 794                self.buffers
 795                    .borrow()
 796                    .get(&excerpt.buffer_id)
 797                    .unwrap()
 798                    .buffer
 799                    .clone(),
 800                excerpt.range.clone(),
 801            )
 802        })
 803    }
 804
 805    pub fn range_to_buffer_ranges<'a, T: ToOffset>(
 806        &'a self,
 807        range: Range<T>,
 808        cx: &AppContext,
 809    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 810        let snapshot = self.read(cx);
 811        let start = range.start.to_offset(&snapshot);
 812        let end = range.end.to_offset(&snapshot);
 813
 814        let mut result = Vec::new();
 815        let mut cursor = snapshot.excerpts.cursor::<usize>();
 816        cursor.seek(&start, Bias::Right, &());
 817        while let Some(excerpt) = cursor.item() {
 818            if *cursor.start() > end {
 819                break;
 820            }
 821
 822            let mut end_before_newline = cursor.end(&());
 823            if excerpt.has_trailing_newline {
 824                end_before_newline -= 1;
 825            }
 826            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 827            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 828            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 829            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 830            result.push((buffer, start..end));
 831            cursor.next(&());
 832        }
 833
 834        result
 835    }
 836
 837    pub fn remove_excerpts<'a>(
 838        &mut self,
 839        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 840        cx: &mut ModelContext<Self>,
 841    ) {
 842        let mut buffers = self.buffers.borrow_mut();
 843        let mut snapshot = self.snapshot.borrow_mut();
 844        let mut new_excerpts = SumTree::new();
 845        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 846        let mut edits = Vec::new();
 847        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 848
 849        while let Some(mut excerpt_id) = excerpt_ids.next() {
 850            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 851            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 852            if let Some(mut excerpt) = cursor.item() {
 853                if excerpt.id != *excerpt_id {
 854                    continue;
 855                }
 856                let mut old_start = cursor.start().1;
 857
 858                // Skip over the removed excerpt.
 859                loop {
 860                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 861                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 862                        if buffer_state.excerpts.is_empty() {
 863                            buffers.remove(&excerpt.buffer_id);
 864                        }
 865                    }
 866                    cursor.next(&());
 867
 868                    // Skip over any subsequent excerpts that are also removed.
 869                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 870                        if let Some(next_excerpt) = cursor.item() {
 871                            if next_excerpt.id == *next_excerpt_id {
 872                                excerpt = next_excerpt;
 873                                excerpt_id = excerpt_ids.next().unwrap();
 874                                continue;
 875                            }
 876                        }
 877                    }
 878
 879                    break;
 880                }
 881
 882                // When removing the last excerpt, remove the trailing newline from
 883                // the previous excerpt.
 884                if cursor.item().is_none() && old_start > 0 {
 885                    old_start -= 1;
 886                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 887                }
 888
 889                // Push an edit for the removal of this run of excerpts.
 890                let old_end = cursor.start().1;
 891                let new_start = new_excerpts.summary().text.bytes;
 892                edits.push(Edit {
 893                    old: old_start..old_end,
 894                    new: new_start..new_start,
 895                });
 896            }
 897        }
 898        let suffix = cursor.suffix(&());
 899        let changed_trailing_excerpt = suffix.is_empty();
 900        new_excerpts.push_tree(suffix, &());
 901        drop(cursor);
 902        snapshot.excerpts = new_excerpts;
 903        if changed_trailing_excerpt {
 904            snapshot.trailing_excerpt_update_count += 1;
 905        }
 906
 907        self.subscriptions.publish_mut(edits);
 908        cx.notify();
 909    }
 910
 911    pub fn text_anchor_for_position<'a, T: ToOffset>(
 912        &'a self,
 913        position: T,
 914        cx: &AppContext,
 915    ) -> Option<(ModelHandle<Buffer>, language::Anchor)> {
 916        let snapshot = self.read(cx);
 917        let anchor = snapshot.anchor_before(position);
 918        Some((
 919            self.buffers.borrow()[&anchor.buffer_id?].buffer.clone(),
 920            anchor.text_anchor,
 921        ))
 922    }
 923
 924    fn on_buffer_event(
 925        &mut self,
 926        _: ModelHandle<Buffer>,
 927        event: &Event,
 928        cx: &mut ModelContext<Self>,
 929    ) {
 930        cx.emit(event.clone());
 931    }
 932
 933    pub fn all_buffers(&self) -> HashSet<ModelHandle<Buffer>> {
 934        self.buffers
 935            .borrow()
 936            .values()
 937            .map(|state| state.buffer.clone())
 938            .collect()
 939    }
 940
 941    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
 942        let mut save_tasks = Vec::new();
 943        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 944            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx)));
 945        }
 946
 947        cx.spawn(|_, _| async move {
 948            for save in save_tasks {
 949                save.await?;
 950            }
 951            Ok(())
 952        })
 953    }
 954
 955    pub fn is_completion_trigger<T>(&self, position: T, text: &str, cx: &AppContext) -> bool
 956    where
 957        T: ToOffset,
 958    {
 959        let mut chars = text.chars();
 960        let char = if let Some(char) = chars.next() {
 961            char
 962        } else {
 963            return false;
 964        };
 965        if chars.next().is_some() {
 966            return false;
 967        }
 968
 969        if char.is_alphanumeric() || char == '_' {
 970            return true;
 971        }
 972
 973        let snapshot = self.snapshot(cx);
 974        let anchor = snapshot.anchor_before(position);
 975        anchor.buffer_id.map_or(false, |buffer_id| {
 976            let buffer = self.buffers.borrow()[&buffer_id].buffer.clone();
 977            buffer
 978                .read(cx)
 979                .completion_triggers()
 980                .iter()
 981                .any(|string| string == text)
 982        })
 983    }
 984
 985    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 986        self.buffers
 987            .borrow()
 988            .values()
 989            .next()
 990            .and_then(|state| state.buffer.read(cx).language())
 991    }
 992
 993    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 994        self.as_singleton()?.read(cx).file()
 995    }
 996
 997    pub fn title(&self, cx: &AppContext) -> String {
 998        if let Some(title) = self.title.clone() {
 999            title
1000        } else if let Some(file) = self.file(cx) {
1001            file.file_name(cx).to_string_lossy().into()
1002        } else {
1003            "untitled".into()
1004        }
1005    }
1006
1007    #[cfg(test)]
1008    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1009        self.as_singleton().unwrap().read(cx).is_parsing()
1010    }
1011
1012    fn sync(&self, cx: &AppContext) {
1013        let mut snapshot = self.snapshot.borrow_mut();
1014        let mut excerpts_to_edit = Vec::new();
1015        let mut reparsed = false;
1016        let mut diagnostics_updated = false;
1017        let mut is_dirty = false;
1018        let mut has_conflict = false;
1019        let mut buffers = self.buffers.borrow_mut();
1020        for buffer_state in buffers.values_mut() {
1021            let buffer = buffer_state.buffer.read(cx);
1022            let version = buffer.version();
1023            let parse_count = buffer.parse_count();
1024            let selections_update_count = buffer.selections_update_count();
1025            let diagnostics_update_count = buffer.diagnostics_update_count();
1026            let file_update_count = buffer.file_update_count();
1027
1028            let buffer_edited = version.changed_since(&buffer_state.last_version);
1029            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1030            let buffer_selections_updated =
1031                selections_update_count > buffer_state.last_selections_update_count;
1032            let buffer_diagnostics_updated =
1033                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1034            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1035            if buffer_edited
1036                || buffer_reparsed
1037                || buffer_selections_updated
1038                || buffer_diagnostics_updated
1039                || buffer_file_updated
1040            {
1041                buffer_state.last_version = version;
1042                buffer_state.last_parse_count = parse_count;
1043                buffer_state.last_selections_update_count = selections_update_count;
1044                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1045                buffer_state.last_file_update_count = file_update_count;
1046                excerpts_to_edit.extend(
1047                    buffer_state
1048                        .excerpts
1049                        .iter()
1050                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
1051                );
1052            }
1053
1054            reparsed |= buffer_reparsed;
1055            diagnostics_updated |= buffer_diagnostics_updated;
1056            is_dirty |= buffer.is_dirty();
1057            has_conflict |= buffer.has_conflict();
1058        }
1059        if reparsed {
1060            snapshot.parse_count += 1;
1061        }
1062        if diagnostics_updated {
1063            snapshot.diagnostics_update_count += 1;
1064        }
1065        snapshot.is_dirty = is_dirty;
1066        snapshot.has_conflict = has_conflict;
1067
1068        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
1069
1070        let mut edits = Vec::new();
1071        let mut new_excerpts = SumTree::new();
1072        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
1073
1074        for (id, buffer, buffer_edited) in excerpts_to_edit {
1075            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
1076            let old_excerpt = cursor.item().unwrap();
1077            let buffer_id = buffer.id();
1078            let buffer = buffer.read(cx);
1079
1080            let mut new_excerpt;
1081            if buffer_edited {
1082                edits.extend(
1083                    buffer
1084                        .edits_since_in_range::<usize>(
1085                            old_excerpt.buffer.version(),
1086                            old_excerpt.range.clone(),
1087                        )
1088                        .map(|mut edit| {
1089                            let excerpt_old_start = cursor.start().1;
1090                            let excerpt_new_start = new_excerpts.summary().text.bytes;
1091                            edit.old.start += excerpt_old_start;
1092                            edit.old.end += excerpt_old_start;
1093                            edit.new.start += excerpt_new_start;
1094                            edit.new.end += excerpt_new_start;
1095                            edit
1096                        }),
1097                );
1098
1099                new_excerpt = Excerpt::new(
1100                    id.clone(),
1101                    buffer_id,
1102                    buffer.snapshot(),
1103                    old_excerpt.range.clone(),
1104                    old_excerpt.has_trailing_newline,
1105                );
1106            } else {
1107                new_excerpt = old_excerpt.clone();
1108                new_excerpt.buffer = buffer.snapshot();
1109            }
1110
1111            new_excerpts.push(new_excerpt, &());
1112            cursor.next(&());
1113        }
1114        new_excerpts.push_tree(cursor.suffix(&()), &());
1115
1116        drop(cursor);
1117        snapshot.excerpts = new_excerpts;
1118
1119        self.subscriptions.publish(edits);
1120    }
1121}
1122
1123#[cfg(any(test, feature = "test-support"))]
1124impl MultiBuffer {
1125    pub fn randomly_edit(
1126        &mut self,
1127        rng: &mut impl rand::Rng,
1128        count: usize,
1129        cx: &mut ModelContext<Self>,
1130    ) {
1131        use text::RandomCharIter;
1132
1133        let snapshot = self.read(cx);
1134        let mut old_ranges: Vec<Range<usize>> = Vec::new();
1135        for _ in 0..count {
1136            let last_end = old_ranges.last().map_or(0, |last_range| last_range.end + 1);
1137            if last_end > snapshot.len() {
1138                break;
1139            }
1140            let end_ix = snapshot.clip_offset(rng.gen_range(0..=last_end), Bias::Right);
1141            let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1142            old_ranges.push(start_ix..end_ix);
1143        }
1144        let new_text_len = rng.gen_range(0..10);
1145        let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1146        log::info!("mutating multi-buffer at {:?}: {:?}", old_ranges, new_text);
1147        drop(snapshot);
1148
1149        self.edit(old_ranges.iter().cloned(), new_text.as_str(), cx);
1150    }
1151
1152    pub fn randomly_edit_excerpts(
1153        &mut self,
1154        rng: &mut impl rand::Rng,
1155        mutation_count: usize,
1156        cx: &mut ModelContext<Self>,
1157    ) {
1158        use rand::prelude::*;
1159        use std::env;
1160        use text::RandomCharIter;
1161
1162        let max_excerpts = env::var("MAX_EXCERPTS")
1163            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1164            .unwrap_or(5);
1165
1166        let mut buffers = Vec::new();
1167        for _ in 0..mutation_count {
1168            let excerpt_ids = self
1169                .buffers
1170                .borrow()
1171                .values()
1172                .flat_map(|b| &b.excerpts)
1173                .cloned()
1174                .collect::<Vec<_>>();
1175            if excerpt_ids.len() == 0 || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1176                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1177                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1178                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
1179                    let buffer = buffers.last().unwrap();
1180                    log::info!(
1181                        "Creating new buffer {} with text: {:?}",
1182                        buffer.id(),
1183                        buffer.read(cx).text()
1184                    );
1185                    buffers.last().unwrap().clone()
1186                } else {
1187                    self.buffers
1188                        .borrow()
1189                        .values()
1190                        .choose(rng)
1191                        .unwrap()
1192                        .buffer
1193                        .clone()
1194                };
1195
1196                let buffer = buffer_handle.read(cx);
1197                let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1198                let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1199                log::info!(
1200                    "Inserting excerpt from buffer {} and range {:?}: {:?}",
1201                    buffer_handle.id(),
1202                    start_ix..end_ix,
1203                    &buffer.text()[start_ix..end_ix]
1204                );
1205
1206                let excerpt_id = self.push_excerpts(buffer_handle.clone(), [start_ix..end_ix], cx);
1207                log::info!("Inserted with id: {:?}", excerpt_id);
1208            } else {
1209                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1210                let mut excerpts_to_remove = excerpt_ids
1211                    .choose_multiple(rng, remove_count)
1212                    .cloned()
1213                    .collect::<Vec<_>>();
1214                excerpts_to_remove.sort();
1215                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1216                self.remove_excerpts(&excerpts_to_remove, cx);
1217            }
1218        }
1219    }
1220
1221    pub fn randomly_mutate(
1222        &mut self,
1223        rng: &mut impl rand::Rng,
1224        mutation_count: usize,
1225        cx: &mut ModelContext<Self>,
1226    ) {
1227        if rng.gen_bool(0.7) || self.singleton {
1228            self.randomly_edit(rng, mutation_count, cx);
1229        } else {
1230            self.randomly_edit_excerpts(rng, mutation_count, cx);
1231        }
1232    }
1233}
1234
1235impl Entity for MultiBuffer {
1236    type Event = language::Event;
1237}
1238
1239impl MultiBufferSnapshot {
1240    pub fn text(&self) -> String {
1241        self.chunks(0..self.len(), false)
1242            .map(|chunk| chunk.text)
1243            .collect()
1244    }
1245
1246    pub fn reversed_chars_at<'a, T: ToOffset>(
1247        &'a self,
1248        position: T,
1249    ) -> impl Iterator<Item = char> + 'a {
1250        let mut offset = position.to_offset(self);
1251        let mut cursor = self.excerpts.cursor::<usize>();
1252        cursor.seek(&offset, Bias::Left, &());
1253        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1254            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1255            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1256            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1257            excerpt.buffer.reversed_chunks_in_range(start..end)
1258        });
1259        iter::from_fn(move || {
1260            if offset == *cursor.start() {
1261                cursor.prev(&());
1262                let excerpt = cursor.item()?;
1263                excerpt_chunks = Some(
1264                    excerpt
1265                        .buffer
1266                        .reversed_chunks_in_range(excerpt.range.clone()),
1267                );
1268            }
1269
1270            let excerpt = cursor.item().unwrap();
1271            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1272                offset -= 1;
1273                Some("\n")
1274            } else {
1275                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1276                offset -= chunk.len();
1277                Some(chunk)
1278            }
1279        })
1280        .flat_map(|c| c.chars().rev())
1281    }
1282
1283    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1284        let offset = position.to_offset(self);
1285        self.text_for_range(offset..self.len())
1286            .flat_map(|chunk| chunk.chars())
1287    }
1288
1289    pub fn text_for_range<'a, T: ToOffset>(
1290        &'a self,
1291        range: Range<T>,
1292    ) -> impl Iterator<Item = &'a str> {
1293        self.chunks(range, false).map(|chunk| chunk.text)
1294    }
1295
1296    pub fn is_line_blank(&self, row: u32) -> bool {
1297        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1298            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1299    }
1300
1301    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1302    where
1303        T: ToOffset,
1304    {
1305        let position = position.to_offset(self);
1306        position == self.clip_offset(position, Bias::Left)
1307            && self
1308                .bytes_in_range(position..self.len())
1309                .flatten()
1310                .copied()
1311                .take(needle.len())
1312                .eq(needle.bytes())
1313    }
1314
1315    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
1316        let mut start = start.to_offset(self);
1317        let mut end = start;
1318        let mut next_chars = self.chars_at(start).peekable();
1319        let mut prev_chars = self.reversed_chars_at(start).peekable();
1320        let word_kind = cmp::max(
1321            prev_chars.peek().copied().map(char_kind),
1322            next_chars.peek().copied().map(char_kind),
1323        );
1324
1325        for ch in prev_chars {
1326            if Some(char_kind(ch)) == word_kind {
1327                start -= ch.len_utf8();
1328            } else {
1329                break;
1330            }
1331        }
1332
1333        for ch in next_chars {
1334            if Some(char_kind(ch)) == word_kind {
1335                end += ch.len_utf8();
1336            } else {
1337                break;
1338            }
1339        }
1340
1341        (start..end, word_kind)
1342    }
1343
1344    fn as_singleton(&self) -> Option<&Excerpt> {
1345        if self.singleton {
1346            self.excerpts.iter().next()
1347        } else {
1348            None
1349        }
1350    }
1351
1352    pub fn len(&self) -> usize {
1353        self.excerpts.summary().text.bytes
1354    }
1355
1356    pub fn max_buffer_row(&self) -> u32 {
1357        self.excerpts.summary().max_buffer_row
1358    }
1359
1360    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1361        if let Some(excerpt) = self.as_singleton() {
1362            return excerpt.buffer.clip_offset(offset, bias);
1363        }
1364
1365        let mut cursor = self.excerpts.cursor::<usize>();
1366        cursor.seek(&offset, Bias::Right, &());
1367        let overshoot = if let Some(excerpt) = cursor.item() {
1368            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1369            let buffer_offset = excerpt
1370                .buffer
1371                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1372            buffer_offset.saturating_sub(excerpt_start)
1373        } else {
1374            0
1375        };
1376        cursor.start() + overshoot
1377    }
1378
1379    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1380        if let Some(excerpt) = self.as_singleton() {
1381            return excerpt.buffer.clip_point(point, bias);
1382        }
1383
1384        let mut cursor = self.excerpts.cursor::<Point>();
1385        cursor.seek(&point, Bias::Right, &());
1386        let overshoot = if let Some(excerpt) = cursor.item() {
1387            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1388            let buffer_point = excerpt
1389                .buffer
1390                .clip_point(excerpt_start + (point - cursor.start()), bias);
1391            buffer_point.saturating_sub(excerpt_start)
1392        } else {
1393            Point::zero()
1394        };
1395        *cursor.start() + overshoot
1396    }
1397
1398    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1399        if let Some(excerpt) = self.as_singleton() {
1400            return excerpt.buffer.clip_point_utf16(point, bias);
1401        }
1402
1403        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1404        cursor.seek(&point, Bias::Right, &());
1405        let overshoot = if let Some(excerpt) = cursor.item() {
1406            let excerpt_start = excerpt
1407                .buffer
1408                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1409            let buffer_point = excerpt
1410                .buffer
1411                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1412            buffer_point.saturating_sub(excerpt_start)
1413        } else {
1414            PointUtf16::zero()
1415        };
1416        *cursor.start() + overshoot
1417    }
1418
1419    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1420        let range = range.start.to_offset(self)..range.end.to_offset(self);
1421        let mut excerpts = self.excerpts.cursor::<usize>();
1422        excerpts.seek(&range.start, Bias::Right, &());
1423
1424        let mut chunk = &[][..];
1425        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1426            let mut excerpt_bytes = excerpt
1427                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1428            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1429            Some(excerpt_bytes)
1430        } else {
1431            None
1432        };
1433
1434        MultiBufferBytes {
1435            range,
1436            excerpts,
1437            excerpt_bytes,
1438            chunk,
1439        }
1440    }
1441
1442    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1443        let mut result = MultiBufferRows {
1444            buffer_row_range: 0..0,
1445            excerpts: self.excerpts.cursor(),
1446        };
1447        result.seek(start_row);
1448        result
1449    }
1450
1451    pub fn chunks<'a, T: ToOffset>(
1452        &'a self,
1453        range: Range<T>,
1454        language_aware: bool,
1455    ) -> MultiBufferChunks<'a> {
1456        let range = range.start.to_offset(self)..range.end.to_offset(self);
1457        let mut chunks = MultiBufferChunks {
1458            range: range.clone(),
1459            excerpts: self.excerpts.cursor(),
1460            excerpt_chunks: None,
1461            language_aware,
1462        };
1463        chunks.seek(range.start);
1464        chunks
1465    }
1466
1467    pub fn offset_to_point(&self, offset: usize) -> Point {
1468        if let Some(excerpt) = self.as_singleton() {
1469            return excerpt.buffer.offset_to_point(offset);
1470        }
1471
1472        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1473        cursor.seek(&offset, Bias::Right, &());
1474        if let Some(excerpt) = cursor.item() {
1475            let (start_offset, start_point) = cursor.start();
1476            let overshoot = offset - start_offset;
1477            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1478            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1479            let buffer_point = excerpt
1480                .buffer
1481                .offset_to_point(excerpt_start_offset + overshoot);
1482            *start_point + (buffer_point - excerpt_start_point)
1483        } else {
1484            self.excerpts.summary().text.lines
1485        }
1486    }
1487
1488    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
1489        if let Some(excerpt) = self.as_singleton() {
1490            return excerpt.buffer.offset_to_point_utf16(offset);
1491        }
1492
1493        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
1494        cursor.seek(&offset, Bias::Right, &());
1495        if let Some(excerpt) = cursor.item() {
1496            let (start_offset, start_point) = cursor.start();
1497            let overshoot = offset - start_offset;
1498            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1499            let excerpt_start_point = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1500            let buffer_point = excerpt
1501                .buffer
1502                .offset_to_point_utf16(excerpt_start_offset + overshoot);
1503            *start_point + (buffer_point - excerpt_start_point)
1504        } else {
1505            self.excerpts.summary().text.lines_utf16
1506        }
1507    }
1508
1509    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
1510        if let Some(excerpt) = self.as_singleton() {
1511            return excerpt.buffer.point_to_point_utf16(point);
1512        }
1513
1514        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
1515        cursor.seek(&point, Bias::Right, &());
1516        if let Some(excerpt) = cursor.item() {
1517            let (start_offset, start_point) = cursor.start();
1518            let overshoot = point - start_offset;
1519            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1520            let excerpt_start_point_utf16 = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1521            let buffer_point = excerpt
1522                .buffer
1523                .point_to_point_utf16(excerpt_start_point + overshoot);
1524            *start_point + (buffer_point - excerpt_start_point_utf16)
1525        } else {
1526            self.excerpts.summary().text.lines_utf16
1527        }
1528    }
1529
1530    pub fn point_to_offset(&self, point: Point) -> usize {
1531        if let Some(excerpt) = self.as_singleton() {
1532            return excerpt.buffer.point_to_offset(point);
1533        }
1534
1535        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1536        cursor.seek(&point, Bias::Right, &());
1537        if let Some(excerpt) = cursor.item() {
1538            let (start_point, start_offset) = cursor.start();
1539            let overshoot = point - start_point;
1540            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1541            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1542            let buffer_offset = excerpt
1543                .buffer
1544                .point_to_offset(excerpt_start_point + overshoot);
1545            *start_offset + buffer_offset - excerpt_start_offset
1546        } else {
1547            self.excerpts.summary().text.bytes
1548        }
1549    }
1550
1551    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1552        if let Some(excerpt) = self.as_singleton() {
1553            return excerpt.buffer.point_utf16_to_offset(point);
1554        }
1555
1556        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1557        cursor.seek(&point, Bias::Right, &());
1558        if let Some(excerpt) = cursor.item() {
1559            let (start_point, start_offset) = cursor.start();
1560            let overshoot = point - start_point;
1561            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1562            let excerpt_start_point = excerpt
1563                .buffer
1564                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1565            let buffer_offset = excerpt
1566                .buffer
1567                .point_utf16_to_offset(excerpt_start_point + overshoot);
1568            *start_offset + (buffer_offset - excerpt_start_offset)
1569        } else {
1570            self.excerpts.summary().text.bytes
1571        }
1572    }
1573
1574    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1575        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1576            buffer
1577                .indent_column_for_line(range.start.row)
1578                .min(range.end.column)
1579                .saturating_sub(range.start.column)
1580        } else {
1581            0
1582        }
1583    }
1584
1585    pub fn line_len(&self, row: u32) -> u32 {
1586        if let Some((_, range)) = self.buffer_line_for_row(row) {
1587            range.end.column - range.start.column
1588        } else {
1589            0
1590        }
1591    }
1592
1593    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1594        let mut cursor = self.excerpts.cursor::<Point>();
1595        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1596        if let Some(excerpt) = cursor.item() {
1597            let overshoot = row - cursor.start().row;
1598            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1599            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1600            let buffer_row = excerpt_start.row + overshoot;
1601            let line_start = Point::new(buffer_row, 0);
1602            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1603            return Some((
1604                &excerpt.buffer,
1605                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1606            ));
1607        }
1608        None
1609    }
1610
1611    pub fn max_point(&self) -> Point {
1612        self.text_summary().lines
1613    }
1614
1615    pub fn text_summary(&self) -> TextSummary {
1616        self.excerpts.summary().text
1617    }
1618
1619    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1620    where
1621        D: TextDimension,
1622        O: ToOffset,
1623    {
1624        let mut summary = D::default();
1625        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1626        let mut cursor = self.excerpts.cursor::<usize>();
1627        cursor.seek(&range.start, Bias::Right, &());
1628        if let Some(excerpt) = cursor.item() {
1629            let mut end_before_newline = cursor.end(&());
1630            if excerpt.has_trailing_newline {
1631                end_before_newline -= 1;
1632            }
1633
1634            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1635            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1636            let end_in_excerpt =
1637                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1638            summary.add_assign(
1639                &excerpt
1640                    .buffer
1641                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1642            );
1643
1644            if range.end > end_before_newline {
1645                summary.add_assign(&D::from_text_summary(&TextSummary {
1646                    bytes: 1,
1647                    lines: Point::new(1 as u32, 0),
1648                    lines_utf16: PointUtf16::new(1 as u32, 0),
1649                    first_line_chars: 0,
1650                    last_line_chars: 0,
1651                    longest_row: 0,
1652                    longest_row_chars: 0,
1653                }));
1654            }
1655
1656            cursor.next(&());
1657        }
1658
1659        if range.end > *cursor.start() {
1660            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1661                &range.end,
1662                Bias::Right,
1663                &(),
1664            )));
1665            if let Some(excerpt) = cursor.item() {
1666                range.end = cmp::max(*cursor.start(), range.end);
1667
1668                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1669                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1670                summary.add_assign(
1671                    &excerpt
1672                        .buffer
1673                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1674                );
1675            }
1676        }
1677
1678        summary
1679    }
1680
1681    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1682    where
1683        D: TextDimension + Ord + Sub<D, Output = D>,
1684    {
1685        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1686        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1687        if cursor.item().is_none() {
1688            cursor.next(&());
1689        }
1690
1691        let mut position = D::from_text_summary(&cursor.start().text);
1692        if let Some(excerpt) = cursor.item() {
1693            if excerpt.id == anchor.excerpt_id && Some(excerpt.buffer_id) == anchor.buffer_id {
1694                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1695                let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1696                let buffer_position = cmp::min(
1697                    excerpt_buffer_end,
1698                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
1699                );
1700                if buffer_position > excerpt_buffer_start {
1701                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1702                }
1703            }
1704        }
1705        position
1706    }
1707
1708    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1709    where
1710        D: TextDimension + Ord + Sub<D, Output = D>,
1711        I: 'a + IntoIterator<Item = &'a Anchor>,
1712    {
1713        if let Some(excerpt) = self.as_singleton() {
1714            return excerpt
1715                .buffer
1716                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
1717                .collect();
1718        }
1719
1720        let mut anchors = anchors.into_iter().peekable();
1721        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1722        let mut summaries = Vec::new();
1723        while let Some(anchor) = anchors.peek() {
1724            let excerpt_id = &anchor.excerpt_id;
1725            let buffer_id = anchor.buffer_id;
1726            let excerpt_anchors = iter::from_fn(|| {
1727                let anchor = anchors.peek()?;
1728                if anchor.excerpt_id == *excerpt_id && anchor.buffer_id == buffer_id {
1729                    Some(&anchors.next().unwrap().text_anchor)
1730                } else {
1731                    None
1732                }
1733            });
1734
1735            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1736            if cursor.item().is_none() {
1737                cursor.next(&());
1738            }
1739
1740            let position = D::from_text_summary(&cursor.start().text);
1741            if let Some(excerpt) = cursor.item() {
1742                if excerpt.id == *excerpt_id && Some(excerpt.buffer_id) == buffer_id {
1743                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1744                    let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1745                    summaries.extend(
1746                        excerpt
1747                            .buffer
1748                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1749                            .map(move |summary| {
1750                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
1751                                let mut position = position.clone();
1752                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1753                                if summary > excerpt_buffer_start {
1754                                    position.add_assign(&(summary - excerpt_buffer_start));
1755                                }
1756                                position
1757                            }),
1758                    );
1759                    continue;
1760                }
1761            }
1762
1763            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1764        }
1765
1766        summaries
1767    }
1768
1769    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1770    where
1771        I: 'a + IntoIterator<Item = &'a Anchor>,
1772    {
1773        let mut anchors = anchors.into_iter().enumerate().peekable();
1774        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1775        let mut result = Vec::new();
1776        while let Some((_, anchor)) = anchors.peek() {
1777            let old_excerpt_id = &anchor.excerpt_id;
1778
1779            // Find the location where this anchor's excerpt should be.
1780            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1781            if cursor.item().is_none() {
1782                cursor.next(&());
1783            }
1784
1785            let next_excerpt = cursor.item();
1786            let prev_excerpt = cursor.prev_item();
1787
1788            // Process all of the anchors for this excerpt.
1789            while let Some((_, anchor)) = anchors.peek() {
1790                if anchor.excerpt_id != *old_excerpt_id {
1791                    break;
1792                }
1793                let mut kept_position = false;
1794                let (anchor_ix, anchor) = anchors.next().unwrap();
1795                let mut anchor = anchor.clone();
1796
1797                // Leave min and max anchors unchanged.
1798                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1799                    kept_position = true;
1800                }
1801                // If the old excerpt still exists at this location, then leave
1802                // the anchor unchanged.
1803                else if next_excerpt.map_or(false, |excerpt| {
1804                    excerpt.id == *old_excerpt_id && excerpt.contains(&anchor)
1805                }) {
1806                    kept_position = true;
1807                }
1808                // If the old excerpt no longer exists at this location, then attempt to
1809                // find an equivalent position for this anchor in an adjacent excerpt.
1810                else {
1811                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1812                        if excerpt.contains(&anchor) {
1813                            anchor.excerpt_id = excerpt.id.clone();
1814                            kept_position = true;
1815                            break;
1816                        }
1817                    }
1818                }
1819                // If there's no adjacent excerpt that contains the anchor's position,
1820                // then report that the anchor has lost its position.
1821                if !kept_position {
1822                    anchor = if let Some(excerpt) = next_excerpt {
1823                        let mut text_anchor = excerpt
1824                            .range
1825                            .start
1826                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1827                        if text_anchor
1828                            .cmp(&excerpt.range.end, &excerpt.buffer)
1829                            .unwrap()
1830                            .is_gt()
1831                        {
1832                            text_anchor = excerpt.range.end.clone();
1833                        }
1834                        Anchor {
1835                            buffer_id: Some(excerpt.buffer_id),
1836                            excerpt_id: excerpt.id.clone(),
1837                            text_anchor,
1838                        }
1839                    } else if let Some(excerpt) = prev_excerpt {
1840                        let mut text_anchor = excerpt
1841                            .range
1842                            .end
1843                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1844                        if text_anchor
1845                            .cmp(&excerpt.range.start, &excerpt.buffer)
1846                            .unwrap()
1847                            .is_lt()
1848                        {
1849                            text_anchor = excerpt.range.start.clone();
1850                        }
1851                        Anchor {
1852                            buffer_id: Some(excerpt.buffer_id),
1853                            excerpt_id: excerpt.id.clone(),
1854                            text_anchor,
1855                        }
1856                    } else if anchor.text_anchor.bias == Bias::Left {
1857                        Anchor::min()
1858                    } else {
1859                        Anchor::max()
1860                    };
1861                }
1862
1863                result.push((anchor_ix, anchor, kept_position));
1864            }
1865        }
1866        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self).unwrap());
1867        result
1868    }
1869
1870    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1871        self.anchor_at(position, Bias::Left)
1872    }
1873
1874    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1875        self.anchor_at(position, Bias::Right)
1876    }
1877
1878    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
1879        let offset = position.to_offset(self);
1880        if let Some(excerpt) = self.as_singleton() {
1881            return Anchor {
1882                buffer_id: Some(excerpt.buffer_id),
1883                excerpt_id: excerpt.id.clone(),
1884                text_anchor: excerpt.buffer.anchor_at(offset, bias),
1885            };
1886        }
1887
1888        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1889        cursor.seek(&offset, Bias::Right, &());
1890        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
1891            cursor.prev(&());
1892        }
1893        if let Some(excerpt) = cursor.item() {
1894            let mut overshoot = offset.saturating_sub(cursor.start().0);
1895            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
1896                overshoot -= 1;
1897                bias = Bias::Right;
1898            }
1899
1900            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1901            let text_anchor =
1902                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
1903            Anchor {
1904                buffer_id: Some(excerpt.buffer_id),
1905                excerpt_id: excerpt.id.clone(),
1906                text_anchor,
1907            }
1908        } else if offset == 0 && bias == Bias::Left {
1909            Anchor::min()
1910        } else {
1911            Anchor::max()
1912        }
1913    }
1914
1915    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
1916        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1917        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
1918        if let Some(excerpt) = cursor.item() {
1919            if excerpt.id == excerpt_id {
1920                let text_anchor = excerpt.clip_anchor(text_anchor);
1921                drop(cursor);
1922                return Anchor {
1923                    buffer_id: Some(excerpt.buffer_id),
1924                    excerpt_id,
1925                    text_anchor,
1926                };
1927            }
1928        }
1929        panic!("excerpt not found");
1930    }
1931
1932    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
1933        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
1934            true
1935        } else if let Some((buffer_id, buffer_snapshot)) =
1936            self.buffer_snapshot_for_excerpt(&anchor.excerpt_id)
1937        {
1938            anchor.buffer_id == Some(buffer_id) && buffer_snapshot.can_resolve(&anchor.text_anchor)
1939        } else {
1940            false
1941        }
1942    }
1943
1944    pub fn excerpt_boundaries_in_range<'a, R, T>(
1945        &'a self,
1946        range: R,
1947    ) -> impl Iterator<Item = ExcerptBoundary> + 'a
1948    where
1949        R: RangeBounds<T>,
1950        T: ToOffset,
1951    {
1952        let start_offset;
1953        let start = match range.start_bound() {
1954            Bound::Included(start) => {
1955                start_offset = start.to_offset(self);
1956                Bound::Included(start_offset)
1957            }
1958            Bound::Excluded(start) => {
1959                start_offset = start.to_offset(self);
1960                Bound::Excluded(start_offset)
1961            }
1962            Bound::Unbounded => {
1963                start_offset = 0;
1964                Bound::Unbounded
1965            }
1966        };
1967        let end = match range.end_bound() {
1968            Bound::Included(end) => Bound::Included(end.to_offset(self)),
1969            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
1970            Bound::Unbounded => Bound::Unbounded,
1971        };
1972        let bounds = (start, end);
1973
1974        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1975        cursor.seek(&start_offset, Bias::Right, &());
1976        if cursor.item().is_none() {
1977            cursor.prev(&());
1978        }
1979        if !bounds.contains(&cursor.start().0) {
1980            cursor.next(&());
1981        }
1982
1983        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
1984        std::iter::from_fn(move || {
1985            if self.singleton {
1986                None
1987            } else if bounds.contains(&cursor.start().0) {
1988                let excerpt = cursor.item()?;
1989                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
1990                let boundary = ExcerptBoundary {
1991                    row: cursor.start().1.row,
1992                    buffer: excerpt.buffer.clone(),
1993                    range: excerpt.range.clone(),
1994                    starts_new_buffer,
1995                };
1996
1997                prev_buffer_id = Some(excerpt.buffer_id);
1998                cursor.next(&());
1999                Some(boundary)
2000            } else {
2001                None
2002            }
2003        })
2004    }
2005
2006    pub fn parse_count(&self) -> usize {
2007        self.parse_count
2008    }
2009
2010    pub fn enclosing_bracket_ranges<T: ToOffset>(
2011        &self,
2012        range: Range<T>,
2013    ) -> Option<(Range<usize>, Range<usize>)> {
2014        let range = range.start.to_offset(self)..range.end.to_offset(self);
2015
2016        let mut cursor = self.excerpts.cursor::<usize>();
2017        cursor.seek(&range.start, Bias::Right, &());
2018        let start_excerpt = cursor.item();
2019
2020        cursor.seek(&range.end, Bias::Right, &());
2021        let end_excerpt = cursor.item();
2022
2023        start_excerpt
2024            .zip(end_excerpt)
2025            .and_then(|(start_excerpt, end_excerpt)| {
2026                if start_excerpt.id != end_excerpt.id {
2027                    return None;
2028                }
2029
2030                let excerpt_buffer_start =
2031                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2032                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2033
2034                let start_in_buffer =
2035                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2036                let end_in_buffer =
2037                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2038                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
2039                    .buffer
2040                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
2041
2042                if start_bracket_range.start >= excerpt_buffer_start
2043                    && end_bracket_range.end < excerpt_buffer_end
2044                {
2045                    start_bracket_range.start =
2046                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
2047                    start_bracket_range.end =
2048                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
2049                    end_bracket_range.start =
2050                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
2051                    end_bracket_range.end =
2052                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
2053                    Some((start_bracket_range, end_bracket_range))
2054                } else {
2055                    None
2056                }
2057            })
2058    }
2059
2060    pub fn diagnostics_update_count(&self) -> usize {
2061        self.diagnostics_update_count
2062    }
2063
2064    pub fn trailing_excerpt_update_count(&self) -> usize {
2065        self.trailing_excerpt_update_count
2066    }
2067
2068    pub fn language(&self) -> Option<&Arc<Language>> {
2069        self.excerpts
2070            .iter()
2071            .next()
2072            .and_then(|excerpt| excerpt.buffer.language())
2073    }
2074
2075    pub fn is_dirty(&self) -> bool {
2076        self.is_dirty
2077    }
2078
2079    pub fn has_conflict(&self) -> bool {
2080        self.has_conflict
2081    }
2082
2083    pub fn diagnostic_group<'a, O>(
2084        &'a self,
2085        group_id: usize,
2086    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2087    where
2088        O: text::FromAnchor + 'a,
2089    {
2090        self.as_singleton()
2091            .into_iter()
2092            .flat_map(move |excerpt| excerpt.buffer.diagnostic_group(group_id))
2093    }
2094
2095    pub fn diagnostics_in_range<'a, T, O>(
2096        &'a self,
2097        range: Range<T>,
2098    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2099    where
2100        T: 'a + ToOffset,
2101        O: 'a + text::FromAnchor,
2102    {
2103        self.as_singleton().into_iter().flat_map(move |excerpt| {
2104            excerpt
2105                .buffer
2106                .diagnostics_in_range(range.start.to_offset(self)..range.end.to_offset(self))
2107        })
2108    }
2109
2110    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2111        let range = range.start.to_offset(self)..range.end.to_offset(self);
2112
2113        let mut cursor = self.excerpts.cursor::<usize>();
2114        cursor.seek(&range.start, Bias::Right, &());
2115        let start_excerpt = cursor.item();
2116
2117        cursor.seek(&range.end, Bias::Right, &());
2118        let end_excerpt = cursor.item();
2119
2120        start_excerpt
2121            .zip(end_excerpt)
2122            .and_then(|(start_excerpt, end_excerpt)| {
2123                if start_excerpt.id != end_excerpt.id {
2124                    return None;
2125                }
2126
2127                let excerpt_buffer_start =
2128                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2129                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2130
2131                let start_in_buffer =
2132                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2133                let end_in_buffer =
2134                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2135                let mut ancestor_buffer_range = start_excerpt
2136                    .buffer
2137                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2138                ancestor_buffer_range.start =
2139                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2140                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2141
2142                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
2143                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
2144                Some(start..end)
2145            })
2146    }
2147
2148    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2149        let excerpt = self.as_singleton()?;
2150        let outline = excerpt.buffer.outline(theme)?;
2151        Some(Outline::new(
2152            outline
2153                .items
2154                .into_iter()
2155                .map(|item| OutlineItem {
2156                    depth: item.depth,
2157                    range: self.anchor_in_excerpt(excerpt.id.clone(), item.range.start)
2158                        ..self.anchor_in_excerpt(excerpt.id.clone(), item.range.end),
2159                    text: item.text,
2160                    highlight_ranges: item.highlight_ranges,
2161                    name_ranges: item.name_ranges,
2162                })
2163                .collect(),
2164        ))
2165    }
2166
2167    fn buffer_snapshot_for_excerpt<'a>(
2168        &'a self,
2169        excerpt_id: &'a ExcerptId,
2170    ) -> Option<(usize, &'a BufferSnapshot)> {
2171        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2172        cursor.seek(&Some(excerpt_id), Bias::Left, &());
2173        if let Some(excerpt) = cursor.item() {
2174            if excerpt.id == *excerpt_id {
2175                return Some((excerpt.buffer_id, &excerpt.buffer));
2176            }
2177        }
2178        None
2179    }
2180
2181    pub fn remote_selections_in_range<'a>(
2182        &'a self,
2183        range: &'a Range<Anchor>,
2184    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
2185        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2186        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
2187        cursor
2188            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
2189            .flat_map(move |excerpt| {
2190                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
2191                if excerpt.id == range.start.excerpt_id {
2192                    query_range.start = range.start.text_anchor.clone();
2193                }
2194                if excerpt.id == range.end.excerpt_id {
2195                    query_range.end = range.end.text_anchor.clone();
2196                }
2197
2198                excerpt
2199                    .buffer
2200                    .remote_selections_in_range(query_range)
2201                    .flat_map(move |(replica_id, selections)| {
2202                        selections.map(move |selection| {
2203                            let mut start = Anchor {
2204                                buffer_id: Some(excerpt.buffer_id),
2205                                excerpt_id: excerpt.id.clone(),
2206                                text_anchor: selection.start.clone(),
2207                            };
2208                            let mut end = Anchor {
2209                                buffer_id: Some(excerpt.buffer_id),
2210                                excerpt_id: excerpt.id.clone(),
2211                                text_anchor: selection.end.clone(),
2212                            };
2213                            if range.start.cmp(&start, self).unwrap().is_gt() {
2214                                start = range.start.clone();
2215                            }
2216                            if range.end.cmp(&end, self).unwrap().is_lt() {
2217                                end = range.end.clone();
2218                            }
2219
2220                            (
2221                                replica_id,
2222                                Selection {
2223                                    id: selection.id,
2224                                    start,
2225                                    end,
2226                                    reversed: selection.reversed,
2227                                    goal: selection.goal,
2228                                },
2229                            )
2230                        })
2231                    })
2232            })
2233    }
2234}
2235
2236impl History {
2237    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
2238        self.transaction_depth += 1;
2239        if self.transaction_depth == 1 {
2240            let id = self.next_transaction_id.tick();
2241            self.undo_stack.push(Transaction {
2242                id,
2243                buffer_transactions: Default::default(),
2244                first_edit_at: now,
2245                last_edit_at: now,
2246                suppress_grouping: false,
2247            });
2248            Some(id)
2249        } else {
2250            None
2251        }
2252    }
2253
2254    fn end_transaction(
2255        &mut self,
2256        now: Instant,
2257        buffer_transactions: HashMap<usize, TransactionId>,
2258    ) -> bool {
2259        assert_ne!(self.transaction_depth, 0);
2260        self.transaction_depth -= 1;
2261        if self.transaction_depth == 0 {
2262            if buffer_transactions.is_empty() {
2263                self.undo_stack.pop();
2264                false
2265            } else {
2266                let transaction = self.undo_stack.last_mut().unwrap();
2267                transaction.last_edit_at = now;
2268                for (buffer_id, transaction_id) in buffer_transactions {
2269                    transaction
2270                        .buffer_transactions
2271                        .entry(buffer_id)
2272                        .or_insert(transaction_id);
2273                }
2274                true
2275            }
2276        } else {
2277            false
2278        }
2279    }
2280
2281    fn push_transaction<'a, T>(&mut self, buffer_transactions: T, now: Instant)
2282    where
2283        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
2284    {
2285        assert_eq!(self.transaction_depth, 0);
2286        let transaction = Transaction {
2287            id: self.next_transaction_id.tick(),
2288            buffer_transactions: buffer_transactions
2289                .into_iter()
2290                .map(|(buffer, transaction)| (buffer.id(), transaction.id))
2291                .collect(),
2292            first_edit_at: now,
2293            last_edit_at: now,
2294            suppress_grouping: false,
2295        };
2296        if !transaction.buffer_transactions.is_empty() {
2297            self.undo_stack.push(transaction);
2298        }
2299    }
2300
2301    fn finalize_last_transaction(&mut self) {
2302        if let Some(transaction) = self.undo_stack.last_mut() {
2303            transaction.suppress_grouping = true;
2304        }
2305    }
2306
2307    fn pop_undo(&mut self) -> Option<&mut Transaction> {
2308        assert_eq!(self.transaction_depth, 0);
2309        if let Some(transaction) = self.undo_stack.pop() {
2310            self.redo_stack.push(transaction);
2311            self.redo_stack.last_mut()
2312        } else {
2313            None
2314        }
2315    }
2316
2317    fn pop_redo(&mut self) -> Option<&mut Transaction> {
2318        assert_eq!(self.transaction_depth, 0);
2319        if let Some(transaction) = self.redo_stack.pop() {
2320            self.undo_stack.push(transaction);
2321            self.undo_stack.last_mut()
2322        } else {
2323            None
2324        }
2325    }
2326
2327    fn group(&mut self) -> Option<TransactionId> {
2328        let mut new_len = self.undo_stack.len();
2329        let mut transactions = self.undo_stack.iter_mut();
2330
2331        if let Some(mut transaction) = transactions.next_back() {
2332            while let Some(prev_transaction) = transactions.next_back() {
2333                if !prev_transaction.suppress_grouping
2334                    && transaction.first_edit_at - prev_transaction.last_edit_at
2335                        <= self.group_interval
2336                {
2337                    transaction = prev_transaction;
2338                    new_len -= 1;
2339                } else {
2340                    break;
2341                }
2342            }
2343        }
2344
2345        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
2346        if let Some(last_transaction) = transactions_to_keep.last_mut() {
2347            if let Some(transaction) = transactions_to_merge.last() {
2348                last_transaction.last_edit_at = transaction.last_edit_at;
2349            }
2350            for to_merge in transactions_to_merge {
2351                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
2352                    last_transaction
2353                        .buffer_transactions
2354                        .entry(*buffer_id)
2355                        .or_insert(*transaction_id);
2356                }
2357            }
2358        }
2359
2360        self.undo_stack.truncate(new_len);
2361        self.undo_stack.last().map(|t| t.id)
2362    }
2363}
2364
2365impl Excerpt {
2366    fn new(
2367        id: ExcerptId,
2368        buffer_id: usize,
2369        buffer: BufferSnapshot,
2370        range: Range<text::Anchor>,
2371        has_trailing_newline: bool,
2372    ) -> Self {
2373        Excerpt {
2374            id,
2375            max_buffer_row: range.end.to_point(&buffer).row,
2376            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
2377            buffer_id,
2378            buffer,
2379            range,
2380            has_trailing_newline,
2381        }
2382    }
2383
2384    fn chunks_in_range<'a>(
2385        &'a self,
2386        range: Range<usize>,
2387        language_aware: bool,
2388    ) -> ExcerptChunks<'a> {
2389        let content_start = self.range.start.to_offset(&self.buffer);
2390        let chunks_start = content_start + range.start;
2391        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2392
2393        let footer_height = if self.has_trailing_newline
2394            && range.start <= self.text_summary.bytes
2395            && range.end > self.text_summary.bytes
2396        {
2397            1
2398        } else {
2399            0
2400        };
2401
2402        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
2403
2404        ExcerptChunks {
2405            content_chunks,
2406            footer_height,
2407        }
2408    }
2409
2410    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
2411        let content_start = self.range.start.to_offset(&self.buffer);
2412        let bytes_start = content_start + range.start;
2413        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2414        let footer_height = if self.has_trailing_newline
2415            && range.start <= self.text_summary.bytes
2416            && range.end > self.text_summary.bytes
2417        {
2418            1
2419        } else {
2420            0
2421        };
2422        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
2423
2424        ExcerptBytes {
2425            content_bytes,
2426            footer_height,
2427        }
2428    }
2429
2430    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
2431        if text_anchor
2432            .cmp(&self.range.start, &self.buffer)
2433            .unwrap()
2434            .is_lt()
2435        {
2436            self.range.start.clone()
2437        } else if text_anchor
2438            .cmp(&self.range.end, &self.buffer)
2439            .unwrap()
2440            .is_gt()
2441        {
2442            self.range.end.clone()
2443        } else {
2444            text_anchor
2445        }
2446    }
2447
2448    fn contains(&self, anchor: &Anchor) -> bool {
2449        Some(self.buffer_id) == anchor.buffer_id
2450            && self
2451                .range
2452                .start
2453                .cmp(&anchor.text_anchor, &self.buffer)
2454                .unwrap()
2455                .is_le()
2456            && self
2457                .range
2458                .end
2459                .cmp(&anchor.text_anchor, &self.buffer)
2460                .unwrap()
2461                .is_ge()
2462    }
2463}
2464
2465impl fmt::Debug for Excerpt {
2466    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2467        f.debug_struct("Excerpt")
2468            .field("id", &self.id)
2469            .field("buffer_id", &self.buffer_id)
2470            .field("range", &self.range)
2471            .field("text_summary", &self.text_summary)
2472            .field("has_trailing_newline", &self.has_trailing_newline)
2473            .finish()
2474    }
2475}
2476
2477impl sum_tree::Item for Excerpt {
2478    type Summary = ExcerptSummary;
2479
2480    fn summary(&self) -> Self::Summary {
2481        let mut text = self.text_summary.clone();
2482        if self.has_trailing_newline {
2483            text += TextSummary::from("\n");
2484        }
2485        ExcerptSummary {
2486            excerpt_id: self.id.clone(),
2487            max_buffer_row: self.max_buffer_row,
2488            text,
2489        }
2490    }
2491}
2492
2493impl sum_tree::Summary for ExcerptSummary {
2494    type Context = ();
2495
2496    fn add_summary(&mut self, summary: &Self, _: &()) {
2497        debug_assert!(summary.excerpt_id > self.excerpt_id);
2498        self.excerpt_id = summary.excerpt_id.clone();
2499        self.text.add_summary(&summary.text, &());
2500        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2501    }
2502}
2503
2504impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2505    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2506        *self += &summary.text;
2507    }
2508}
2509
2510impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2511    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2512        *self += summary.text.bytes;
2513    }
2514}
2515
2516impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2517    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2518        Ord::cmp(self, &cursor_location.text.bytes)
2519    }
2520}
2521
2522impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2523    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2524        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2525    }
2526}
2527
2528impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2529    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2530        *self += summary.text.lines;
2531    }
2532}
2533
2534impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2535    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2536        *self += summary.text.lines_utf16
2537    }
2538}
2539
2540impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2541    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2542        *self = Some(&summary.excerpt_id);
2543    }
2544}
2545
2546impl<'a> MultiBufferRows<'a> {
2547    pub fn seek(&mut self, row: u32) {
2548        self.buffer_row_range = 0..0;
2549
2550        self.excerpts
2551            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2552        if self.excerpts.item().is_none() {
2553            self.excerpts.prev(&());
2554
2555            if self.excerpts.item().is_none() && row == 0 {
2556                self.buffer_row_range = 0..1;
2557                return;
2558            }
2559        }
2560
2561        if let Some(excerpt) = self.excerpts.item() {
2562            let overshoot = row - self.excerpts.start().row;
2563            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2564            self.buffer_row_range.start = excerpt_start + overshoot;
2565            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2566        }
2567    }
2568}
2569
2570impl<'a> Iterator for MultiBufferRows<'a> {
2571    type Item = Option<u32>;
2572
2573    fn next(&mut self) -> Option<Self::Item> {
2574        loop {
2575            if !self.buffer_row_range.is_empty() {
2576                let row = Some(self.buffer_row_range.start);
2577                self.buffer_row_range.start += 1;
2578                return Some(row);
2579            }
2580            self.excerpts.item()?;
2581            self.excerpts.next(&());
2582            let excerpt = self.excerpts.item()?;
2583            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2584            self.buffer_row_range.end =
2585                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2586        }
2587    }
2588}
2589
2590impl<'a> MultiBufferChunks<'a> {
2591    pub fn offset(&self) -> usize {
2592        self.range.start
2593    }
2594
2595    pub fn seek(&mut self, offset: usize) {
2596        self.range.start = offset;
2597        self.excerpts.seek(&offset, Bias::Right, &());
2598        if let Some(excerpt) = self.excerpts.item() {
2599            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2600                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2601                self.language_aware,
2602            ));
2603        } else {
2604            self.excerpt_chunks = None;
2605        }
2606    }
2607}
2608
2609impl<'a> Iterator for MultiBufferChunks<'a> {
2610    type Item = Chunk<'a>;
2611
2612    fn next(&mut self) -> Option<Self::Item> {
2613        if self.range.is_empty() {
2614            None
2615        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2616            self.range.start += chunk.text.len();
2617            Some(chunk)
2618        } else {
2619            self.excerpts.next(&());
2620            let excerpt = self.excerpts.item()?;
2621            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2622                0..self.range.end - self.excerpts.start(),
2623                self.language_aware,
2624            ));
2625            self.next()
2626        }
2627    }
2628}
2629
2630impl<'a> MultiBufferBytes<'a> {
2631    fn consume(&mut self, len: usize) {
2632        self.range.start += len;
2633        self.chunk = &self.chunk[len..];
2634
2635        if !self.range.is_empty() && self.chunk.is_empty() {
2636            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2637                self.chunk = chunk;
2638            } else {
2639                self.excerpts.next(&());
2640                if let Some(excerpt) = self.excerpts.item() {
2641                    let mut excerpt_bytes =
2642                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2643                    self.chunk = excerpt_bytes.next().unwrap();
2644                    self.excerpt_bytes = Some(excerpt_bytes);
2645                }
2646            }
2647        }
2648    }
2649}
2650
2651impl<'a> Iterator for MultiBufferBytes<'a> {
2652    type Item = &'a [u8];
2653
2654    fn next(&mut self) -> Option<Self::Item> {
2655        let chunk = self.chunk;
2656        if chunk.is_empty() {
2657            None
2658        } else {
2659            self.consume(chunk.len());
2660            Some(chunk)
2661        }
2662    }
2663}
2664
2665impl<'a> io::Read for MultiBufferBytes<'a> {
2666    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2667        let len = cmp::min(buf.len(), self.chunk.len());
2668        buf[..len].copy_from_slice(&self.chunk[..len]);
2669        if len > 0 {
2670            self.consume(len);
2671        }
2672        Ok(len)
2673    }
2674}
2675
2676impl<'a> Iterator for ExcerptBytes<'a> {
2677    type Item = &'a [u8];
2678
2679    fn next(&mut self) -> Option<Self::Item> {
2680        if let Some(chunk) = self.content_bytes.next() {
2681            if !chunk.is_empty() {
2682                return Some(chunk);
2683            }
2684        }
2685
2686        if self.footer_height > 0 {
2687            let result = &NEWLINES[..self.footer_height];
2688            self.footer_height = 0;
2689            return Some(result);
2690        }
2691
2692        None
2693    }
2694}
2695
2696impl<'a> Iterator for ExcerptChunks<'a> {
2697    type Item = Chunk<'a>;
2698
2699    fn next(&mut self) -> Option<Self::Item> {
2700        if let Some(chunk) = self.content_chunks.next() {
2701            return Some(chunk);
2702        }
2703
2704        if self.footer_height > 0 {
2705            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2706            self.footer_height = 0;
2707            return Some(Chunk {
2708                text,
2709                ..Default::default()
2710            });
2711        }
2712
2713        None
2714    }
2715}
2716
2717impl ToOffset for Point {
2718    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2719        snapshot.point_to_offset(*self)
2720    }
2721}
2722
2723impl ToOffset for PointUtf16 {
2724    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2725        snapshot.point_utf16_to_offset(*self)
2726    }
2727}
2728
2729impl ToOffset for usize {
2730    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2731        assert!(*self <= snapshot.len(), "offset is out of range");
2732        *self
2733    }
2734}
2735
2736impl ToPoint for usize {
2737    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2738        snapshot.offset_to_point(*self)
2739    }
2740}
2741
2742impl ToPoint for Point {
2743    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2744        *self
2745    }
2746}
2747
2748impl ToPointUtf16 for usize {
2749    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2750        snapshot.offset_to_point_utf16(*self)
2751    }
2752}
2753
2754impl ToPointUtf16 for Point {
2755    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2756        snapshot.point_to_point_utf16(*self)
2757    }
2758}
2759
2760impl ToPointUtf16 for PointUtf16 {
2761    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
2762        *self
2763    }
2764}
2765
2766pub fn char_kind(c: char) -> CharKind {
2767    if c == '\n' {
2768        CharKind::Newline
2769    } else if c.is_whitespace() {
2770        CharKind::Whitespace
2771    } else if c.is_alphanumeric() || c == '_' {
2772        CharKind::Word
2773    } else {
2774        CharKind::Punctuation
2775    }
2776}
2777
2778#[cfg(test)]
2779mod tests {
2780    use super::*;
2781    use gpui::MutableAppContext;
2782    use language::{Buffer, Rope};
2783    use rand::prelude::*;
2784    use std::env;
2785    use text::{Point, RandomCharIter};
2786    use util::test::sample_text;
2787
2788    #[gpui::test]
2789    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2790        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2791        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2792
2793        let snapshot = multibuffer.read(cx).snapshot(cx);
2794        assert_eq!(snapshot.text(), buffer.read(cx).text());
2795
2796        assert_eq!(
2797            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2798            (0..buffer.read(cx).row_count())
2799                .map(Some)
2800                .collect::<Vec<_>>()
2801        );
2802
2803        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX\n", cx));
2804        let snapshot = multibuffer.read(cx).snapshot(cx);
2805
2806        assert_eq!(snapshot.text(), buffer.read(cx).text());
2807        assert_eq!(
2808            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2809            (0..buffer.read(cx).row_count())
2810                .map(Some)
2811                .collect::<Vec<_>>()
2812        );
2813    }
2814
2815    #[gpui::test]
2816    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2817        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2818        let guest_buffer = cx.add_model(|cx| {
2819            let message = host_buffer.read(cx).to_proto();
2820            Buffer::from_proto(1, message, None, cx).unwrap()
2821        });
2822        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2823        let snapshot = multibuffer.read(cx).snapshot(cx);
2824        assert_eq!(snapshot.text(), "a");
2825
2826        guest_buffer.update(cx, |buffer, cx| buffer.edit([1..1], "b", cx));
2827        let snapshot = multibuffer.read(cx).snapshot(cx);
2828        assert_eq!(snapshot.text(), "ab");
2829
2830        guest_buffer.update(cx, |buffer, cx| buffer.edit([2..2], "c", cx));
2831        let snapshot = multibuffer.read(cx).snapshot(cx);
2832        assert_eq!(snapshot.text(), "abc");
2833    }
2834
2835    #[gpui::test]
2836    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
2837        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2838        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
2839        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
2840
2841        let subscription = multibuffer.update(cx, |multibuffer, cx| {
2842            let subscription = multibuffer.subscribe();
2843            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(1, 2)..Point::new(2, 5)], cx);
2844            assert_eq!(
2845                subscription.consume().into_inner(),
2846                [Edit {
2847                    old: 0..0,
2848                    new: 0..10
2849                }]
2850            );
2851
2852            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(3, 3)..Point::new(4, 4)], cx);
2853            multibuffer.push_excerpts(buffer_2.clone(), [Point::new(3, 1)..Point::new(3, 3)], cx);
2854            assert_eq!(
2855                subscription.consume().into_inner(),
2856                [Edit {
2857                    old: 10..10,
2858                    new: 10..22
2859                }]
2860            );
2861
2862            subscription
2863        });
2864
2865        let snapshot = multibuffer.read(cx).snapshot(cx);
2866        assert_eq!(
2867            snapshot.text(),
2868            concat!(
2869                "bbbb\n",  // Preserve newlines
2870                "ccccc\n", //
2871                "ddd\n",   //
2872                "eeee\n",  //
2873                "jj"       //
2874            )
2875        );
2876        assert_eq!(
2877            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2878            [Some(1), Some(2), Some(3), Some(4), Some(3)]
2879        );
2880        assert_eq!(
2881            snapshot.buffer_rows(2).collect::<Vec<_>>(),
2882            [Some(3), Some(4), Some(3)]
2883        );
2884        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
2885        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
2886
2887        assert_eq!(
2888            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
2889            &[
2890                (0, "bbbb\nccccc".to_string(), true),
2891                (2, "ddd\neeee".to_string(), false),
2892                (4, "jj".to_string(), true),
2893            ]
2894        );
2895        assert_eq!(
2896            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
2897            &[(0, "bbbb\nccccc".to_string(), true)]
2898        );
2899        assert_eq!(
2900            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
2901            &[]
2902        );
2903        assert_eq!(
2904            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
2905            &[]
2906        );
2907        assert_eq!(
2908            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2909            &[(2, "ddd\neeee".to_string(), false)]
2910        );
2911        assert_eq!(
2912            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
2913            &[(2, "ddd\neeee".to_string(), false)]
2914        );
2915        assert_eq!(
2916            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
2917            &[(2, "ddd\neeee".to_string(), false)]
2918        );
2919        assert_eq!(
2920            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
2921            &[(4, "jj".to_string(), true)]
2922        );
2923        assert_eq!(
2924            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
2925            &[]
2926        );
2927
2928        buffer_1.update(cx, |buffer, cx| {
2929            buffer.edit(
2930                [
2931                    Point::new(0, 0)..Point::new(0, 0),
2932                    Point::new(2, 1)..Point::new(2, 3),
2933                ],
2934                "\n",
2935                cx,
2936            );
2937        });
2938
2939        let snapshot = multibuffer.read(cx).snapshot(cx);
2940        assert_eq!(
2941            snapshot.text(),
2942            concat!(
2943                "bbbb\n", // Preserve newlines
2944                "c\n",    //
2945                "cc\n",   //
2946                "ddd\n",  //
2947                "eeee\n", //
2948                "jj"      //
2949            )
2950        );
2951
2952        assert_eq!(
2953            subscription.consume().into_inner(),
2954            [Edit {
2955                old: 6..8,
2956                new: 6..7
2957            }]
2958        );
2959
2960        let snapshot = multibuffer.read(cx).snapshot(cx);
2961        assert_eq!(
2962            snapshot.clip_point(Point::new(0, 5), Bias::Left),
2963            Point::new(0, 4)
2964        );
2965        assert_eq!(
2966            snapshot.clip_point(Point::new(0, 5), Bias::Right),
2967            Point::new(0, 4)
2968        );
2969        assert_eq!(
2970            snapshot.clip_point(Point::new(5, 1), Bias::Right),
2971            Point::new(5, 1)
2972        );
2973        assert_eq!(
2974            snapshot.clip_point(Point::new(5, 2), Bias::Right),
2975            Point::new(5, 2)
2976        );
2977        assert_eq!(
2978            snapshot.clip_point(Point::new(5, 3), Bias::Right),
2979            Point::new(5, 2)
2980        );
2981
2982        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
2983            let buffer_2_excerpt_id = multibuffer.excerpt_ids_for_buffer(&buffer_2)[0].clone();
2984            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
2985            multibuffer.snapshot(cx)
2986        });
2987
2988        assert_eq!(
2989            snapshot.text(),
2990            concat!(
2991                "bbbb\n", // Preserve newlines
2992                "c\n",    //
2993                "cc\n",   //
2994                "ddd\n",  //
2995                "eeee",   //
2996            )
2997        );
2998
2999        fn boundaries_in_range(
3000            range: Range<Point>,
3001            snapshot: &MultiBufferSnapshot,
3002        ) -> Vec<(u32, String, bool)> {
3003            snapshot
3004                .excerpt_boundaries_in_range(range)
3005                .map(|boundary| {
3006                    (
3007                        boundary.row,
3008                        boundary
3009                            .buffer
3010                            .text_for_range(boundary.range)
3011                            .collect::<String>(),
3012                        boundary.starts_new_buffer,
3013                    )
3014                })
3015                .collect::<Vec<_>>()
3016        }
3017    }
3018
3019    #[gpui::test]
3020    fn test_excerpts_with_context_lines(cx: &mut MutableAppContext) {
3021        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
3022        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3023        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
3024            multibuffer.push_excerpts_with_context_lines(
3025                buffer.clone(),
3026                vec![
3027                    Point::new(3, 2)..Point::new(4, 2),
3028                    Point::new(7, 1)..Point::new(7, 3),
3029                    Point::new(15, 0)..Point::new(15, 0),
3030                ],
3031                2,
3032                cx,
3033            )
3034        });
3035
3036        let snapshot = multibuffer.read(cx).snapshot(cx);
3037        assert_eq!(
3038            snapshot.text(),
3039            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
3040        );
3041
3042        assert_eq!(
3043            anchor_ranges
3044                .iter()
3045                .map(|range| range.to_point(&snapshot))
3046                .collect::<Vec<_>>(),
3047            vec![
3048                Point::new(2, 2)..Point::new(3, 2),
3049                Point::new(6, 1)..Point::new(6, 3),
3050                Point::new(12, 0)..Point::new(12, 0)
3051            ]
3052        );
3053    }
3054
3055    #[gpui::test]
3056    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
3057        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3058
3059        let snapshot = multibuffer.read(cx).snapshot(cx);
3060        assert_eq!(snapshot.text(), "");
3061        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
3062        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
3063    }
3064
3065    #[gpui::test]
3066    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
3067        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3068        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3069        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3070        buffer.update(cx, |buffer, cx| {
3071            buffer.edit([0..0], "X", cx);
3072            buffer.edit([5..5], "Y", cx);
3073        });
3074        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3075
3076        assert_eq!(old_snapshot.text(), "abcd");
3077        assert_eq!(new_snapshot.text(), "XabcdY");
3078
3079        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3080        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3081        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
3082        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
3083    }
3084
3085    #[gpui::test]
3086    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
3087        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3088        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
3089        let multibuffer = cx.add_model(|cx| {
3090            let mut multibuffer = MultiBuffer::new(0);
3091            multibuffer.push_excerpts(buffer_1.clone(), [0..4], cx);
3092            multibuffer.push_excerpts(buffer_2.clone(), [0..5], cx);
3093            multibuffer
3094        });
3095        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3096
3097        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
3098        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
3099        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3100        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3101        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3102        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3103
3104        buffer_1.update(cx, |buffer, cx| {
3105            buffer.edit([0..0], "W", cx);
3106            buffer.edit([5..5], "X", cx);
3107        });
3108        buffer_2.update(cx, |buffer, cx| {
3109            buffer.edit([0..0], "Y", cx);
3110            buffer.edit([6..0], "Z", cx);
3111        });
3112        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3113
3114        assert_eq!(old_snapshot.text(), "abcd\nefghi");
3115        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
3116
3117        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3118        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3119        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
3120        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
3121        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
3122        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
3123        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
3124        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
3125        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
3126        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
3127    }
3128
3129    #[gpui::test]
3130    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
3131        cx: &mut MutableAppContext,
3132    ) {
3133        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3134        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
3135        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3136
3137        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
3138        // Add an excerpt from buffer 1 that spans this new insertion.
3139        buffer_1.update(cx, |buffer, cx| buffer.edit([4..4], "123", cx));
3140        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
3141            multibuffer
3142                .push_excerpts(buffer_1.clone(), [0..7], cx)
3143                .pop()
3144                .unwrap()
3145        });
3146
3147        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
3148        assert_eq!(snapshot_1.text(), "abcd123");
3149
3150        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
3151        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
3152            multibuffer.remove_excerpts([&excerpt_id_1], cx);
3153            let mut ids = multibuffer
3154                .push_excerpts(buffer_2.clone(), [0..4, 6..10, 12..16], cx)
3155                .into_iter();
3156            (ids.next().unwrap(), ids.next().unwrap())
3157        });
3158        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
3159        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
3160
3161        // The old excerpt id has been reused.
3162        assert_eq!(excerpt_id_2, excerpt_id_1);
3163
3164        // Resolve some anchors from the previous snapshot in the new snapshot.
3165        // Although there is still an excerpt with the same id, it is for
3166        // a different buffer, so we don't attempt to resolve the old text
3167        // anchor in the new buffer.
3168        assert_eq!(
3169            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
3170            0
3171        );
3172        assert_eq!(
3173            snapshot_2.summaries_for_anchors::<usize, _>(&[
3174                snapshot_1.anchor_before(2),
3175                snapshot_1.anchor_after(3)
3176            ]),
3177            vec![0, 0]
3178        );
3179        let refresh =
3180            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
3181        assert_eq!(
3182            refresh,
3183            &[
3184                (0, snapshot_2.anchor_before(0), false),
3185                (1, snapshot_2.anchor_after(0), false),
3186            ]
3187        );
3188
3189        // Replace the middle excerpt with a smaller excerpt in buffer 2,
3190        // that intersects the old excerpt.
3191        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
3192            multibuffer.remove_excerpts([&excerpt_id_3], cx);
3193            multibuffer
3194                .insert_excerpts_after(&excerpt_id_3, buffer_2.clone(), [5..8], cx)
3195                .pop()
3196                .unwrap()
3197        });
3198
3199        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
3200        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
3201        assert_ne!(excerpt_id_5, excerpt_id_3);
3202
3203        // Resolve some anchors from the previous snapshot in the new snapshot.
3204        // The anchor in the middle excerpt snaps to the beginning of the
3205        // excerpt, since it is not
3206        let anchors = [
3207            snapshot_2.anchor_before(0),
3208            snapshot_2.anchor_after(2),
3209            snapshot_2.anchor_after(6),
3210            snapshot_2.anchor_after(14),
3211        ];
3212        assert_eq!(
3213            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
3214            &[0, 2, 9, 13]
3215        );
3216
3217        let new_anchors = snapshot_3.refresh_anchors(&anchors);
3218        assert_eq!(
3219            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
3220            &[(0, true), (1, true), (2, true), (3, true)]
3221        );
3222        assert_eq!(
3223            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
3224            &[0, 2, 7, 13]
3225        );
3226    }
3227
3228    #[gpui::test(iterations = 100)]
3229    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
3230        let operations = env::var("OPERATIONS")
3231            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
3232            .unwrap_or(10);
3233
3234        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
3235        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3236        let mut excerpt_ids = Vec::new();
3237        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
3238        let mut anchors = Vec::new();
3239        let mut old_versions = Vec::new();
3240
3241        for _ in 0..operations {
3242            match rng.gen_range(0..100) {
3243                0..=19 if !buffers.is_empty() => {
3244                    let buffer = buffers.choose(&mut rng).unwrap();
3245                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
3246                }
3247                20..=29 if !expected_excerpts.is_empty() => {
3248                    let mut ids_to_remove = vec![];
3249                    for _ in 0..rng.gen_range(1..=3) {
3250                        if expected_excerpts.is_empty() {
3251                            break;
3252                        }
3253
3254                        let ix = rng.gen_range(0..expected_excerpts.len());
3255                        ids_to_remove.push(excerpt_ids.remove(ix));
3256                        let (buffer, range) = expected_excerpts.remove(ix);
3257                        let buffer = buffer.read(cx);
3258                        log::info!(
3259                            "Removing excerpt {}: {:?}",
3260                            ix,
3261                            buffer
3262                                .text_for_range(range.to_offset(&buffer))
3263                                .collect::<String>(),
3264                        );
3265                    }
3266                    ids_to_remove.sort_unstable();
3267                    multibuffer.update(cx, |multibuffer, cx| {
3268                        multibuffer.remove_excerpts(&ids_to_remove, cx)
3269                    });
3270                }
3271                30..=39 if !expected_excerpts.is_empty() => {
3272                    let multibuffer = multibuffer.read(cx).read(cx);
3273                    let offset =
3274                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
3275                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
3276                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
3277                    anchors.push(multibuffer.anchor_at(offset, bias));
3278                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer).unwrap());
3279                }
3280                40..=44 if !anchors.is_empty() => {
3281                    let multibuffer = multibuffer.read(cx).read(cx);
3282
3283                    anchors = multibuffer
3284                        .refresh_anchors(&anchors)
3285                        .into_iter()
3286                        .map(|a| a.1)
3287                        .collect();
3288
3289                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
3290                    // overshoot its boundaries.
3291                    let mut cursor = multibuffer.excerpts.cursor::<Option<&ExcerptId>>();
3292                    for anchor in &anchors {
3293                        if anchor.excerpt_id == ExcerptId::min()
3294                            || anchor.excerpt_id == ExcerptId::max()
3295                        {
3296                            continue;
3297                        }
3298
3299                        cursor.seek_forward(&Some(&anchor.excerpt_id), Bias::Left, &());
3300                        let excerpt = cursor.item().unwrap();
3301                        assert_eq!(excerpt.id, anchor.excerpt_id);
3302                        assert!(excerpt.contains(anchor));
3303                    }
3304                }
3305                _ => {
3306                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
3307                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
3308                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
3309                        buffers.last().unwrap()
3310                    } else {
3311                        buffers.choose(&mut rng).unwrap()
3312                    };
3313
3314                    let buffer = buffer_handle.read(cx);
3315                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3316                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3317                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3318                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
3319                    let prev_excerpt_id = excerpt_ids
3320                        .get(prev_excerpt_ix)
3321                        .cloned()
3322                        .unwrap_or(ExcerptId::max());
3323                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
3324
3325                    log::info!(
3326                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
3327                        excerpt_ix,
3328                        expected_excerpts.len(),
3329                        buffer_handle.id(),
3330                        buffer.text(),
3331                        start_ix..end_ix,
3332                        &buffer.text()[start_ix..end_ix]
3333                    );
3334
3335                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3336                        multibuffer
3337                            .insert_excerpts_after(
3338                                &prev_excerpt_id,
3339                                buffer_handle.clone(),
3340                                [start_ix..end_ix],
3341                                cx,
3342                            )
3343                            .pop()
3344                            .unwrap()
3345                    });
3346
3347                    excerpt_ids.insert(excerpt_ix, excerpt_id);
3348                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
3349                }
3350            }
3351
3352            if rng.gen_bool(0.3) {
3353                multibuffer.update(cx, |multibuffer, cx| {
3354                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
3355                })
3356            }
3357
3358            let snapshot = multibuffer.read(cx).snapshot(cx);
3359
3360            let mut excerpt_starts = Vec::new();
3361            let mut expected_text = String::new();
3362            let mut expected_buffer_rows = Vec::new();
3363            for (buffer, range) in &expected_excerpts {
3364                let buffer = buffer.read(cx);
3365                let buffer_range = range.to_offset(buffer);
3366
3367                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
3368                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
3369                expected_text.push('\n');
3370
3371                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
3372                    ..=buffer.offset_to_point(buffer_range.end).row;
3373                for row in buffer_row_range {
3374                    expected_buffer_rows.push(Some(row));
3375                }
3376            }
3377            // Remove final trailing newline.
3378            if !expected_excerpts.is_empty() {
3379                expected_text.pop();
3380            }
3381
3382            // Always report one buffer row
3383            if expected_buffer_rows.is_empty() {
3384                expected_buffer_rows.push(Some(0));
3385            }
3386
3387            assert_eq!(snapshot.text(), expected_text);
3388            log::info!("MultiBuffer text: {:?}", expected_text);
3389
3390            assert_eq!(
3391                snapshot.buffer_rows(0).collect::<Vec<_>>(),
3392                expected_buffer_rows,
3393            );
3394
3395            for _ in 0..5 {
3396                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
3397                assert_eq!(
3398                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
3399                    &expected_buffer_rows[start_row..],
3400                    "buffer_rows({})",
3401                    start_row
3402                );
3403            }
3404
3405            assert_eq!(
3406                snapshot.max_buffer_row(),
3407                expected_buffer_rows
3408                    .into_iter()
3409                    .filter_map(|r| r)
3410                    .max()
3411                    .unwrap()
3412            );
3413
3414            let mut excerpt_starts = excerpt_starts.into_iter();
3415            for (buffer, range) in &expected_excerpts {
3416                let buffer_id = buffer.id();
3417                let buffer = buffer.read(cx);
3418                let buffer_range = range.to_offset(buffer);
3419                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
3420                let buffer_start_point_utf16 =
3421                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
3422
3423                let excerpt_start = excerpt_starts.next().unwrap();
3424                let mut offset = excerpt_start.bytes;
3425                let mut buffer_offset = buffer_range.start;
3426                let mut point = excerpt_start.lines;
3427                let mut buffer_point = buffer_start_point;
3428                let mut point_utf16 = excerpt_start.lines_utf16;
3429                let mut buffer_point_utf16 = buffer_start_point_utf16;
3430                for ch in buffer
3431                    .snapshot()
3432                    .chunks(buffer_range.clone(), false)
3433                    .flat_map(|c| c.text.chars())
3434                {
3435                    for _ in 0..ch.len_utf8() {
3436                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
3437                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
3438                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
3439                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
3440                        assert_eq!(
3441                            left_offset,
3442                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
3443                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
3444                            offset,
3445                            buffer_id,
3446                            buffer_offset,
3447                        );
3448                        assert_eq!(
3449                            right_offset,
3450                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
3451                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
3452                            offset,
3453                            buffer_id,
3454                            buffer_offset,
3455                        );
3456
3457                        let left_point = snapshot.clip_point(point, Bias::Left);
3458                        let right_point = snapshot.clip_point(point, Bias::Right);
3459                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
3460                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
3461                        assert_eq!(
3462                            left_point,
3463                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
3464                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
3465                            point,
3466                            buffer_id,
3467                            buffer_point,
3468                        );
3469                        assert_eq!(
3470                            right_point,
3471                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
3472                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
3473                            point,
3474                            buffer_id,
3475                            buffer_point,
3476                        );
3477
3478                        assert_eq!(
3479                            snapshot.point_to_offset(left_point),
3480                            left_offset,
3481                            "point_to_offset({:?})",
3482                            left_point,
3483                        );
3484                        assert_eq!(
3485                            snapshot.offset_to_point(left_offset),
3486                            left_point,
3487                            "offset_to_point({:?})",
3488                            left_offset,
3489                        );
3490
3491                        offset += 1;
3492                        buffer_offset += 1;
3493                        if ch == '\n' {
3494                            point += Point::new(1, 0);
3495                            buffer_point += Point::new(1, 0);
3496                        } else {
3497                            point += Point::new(0, 1);
3498                            buffer_point += Point::new(0, 1);
3499                        }
3500                    }
3501
3502                    for _ in 0..ch.len_utf16() {
3503                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
3504                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
3505                        let buffer_left_point_utf16 =
3506                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
3507                        let buffer_right_point_utf16 =
3508                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
3509                        assert_eq!(
3510                            left_point_utf16,
3511                            excerpt_start.lines_utf16
3512                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
3513                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
3514                            point_utf16,
3515                            buffer_id,
3516                            buffer_point_utf16,
3517                        );
3518                        assert_eq!(
3519                            right_point_utf16,
3520                            excerpt_start.lines_utf16
3521                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
3522                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
3523                            point_utf16,
3524                            buffer_id,
3525                            buffer_point_utf16,
3526                        );
3527
3528                        if ch == '\n' {
3529                            point_utf16 += PointUtf16::new(1, 0);
3530                            buffer_point_utf16 += PointUtf16::new(1, 0);
3531                        } else {
3532                            point_utf16 += PointUtf16::new(0, 1);
3533                            buffer_point_utf16 += PointUtf16::new(0, 1);
3534                        }
3535                    }
3536                }
3537            }
3538
3539            for (row, line) in expected_text.split('\n').enumerate() {
3540                assert_eq!(
3541                    snapshot.line_len(row as u32),
3542                    line.len() as u32,
3543                    "line_len({}).",
3544                    row
3545                );
3546            }
3547
3548            let text_rope = Rope::from(expected_text.as_str());
3549            for _ in 0..10 {
3550                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3551                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3552
3553                let text_for_range = snapshot
3554                    .text_for_range(start_ix..end_ix)
3555                    .collect::<String>();
3556                assert_eq!(
3557                    text_for_range,
3558                    &expected_text[start_ix..end_ix],
3559                    "incorrect text for range {:?}",
3560                    start_ix..end_ix
3561                );
3562
3563                let excerpted_buffer_ranges = multibuffer
3564                    .read(cx)
3565                    .range_to_buffer_ranges(start_ix..end_ix, cx);
3566                let excerpted_buffers_text = excerpted_buffer_ranges
3567                    .into_iter()
3568                    .map(|(buffer, buffer_range)| {
3569                        buffer
3570                            .read(cx)
3571                            .text_for_range(buffer_range)
3572                            .collect::<String>()
3573                    })
3574                    .collect::<Vec<_>>()
3575                    .join("\n");
3576                assert_eq!(excerpted_buffers_text, text_for_range);
3577
3578                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3579                assert_eq!(
3580                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3581                    expected_summary,
3582                    "incorrect summary for range {:?}",
3583                    start_ix..end_ix
3584                );
3585            }
3586
3587            // Anchor resolution
3588            for (anchor, resolved_offset) in anchors
3589                .iter()
3590                .zip(snapshot.summaries_for_anchors::<usize, _>(&anchors))
3591            {
3592                assert!(resolved_offset <= snapshot.len());
3593                assert_eq!(
3594                    snapshot.summary_for_anchor::<usize>(anchor),
3595                    resolved_offset
3596                );
3597            }
3598
3599            for _ in 0..10 {
3600                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3601                assert_eq!(
3602                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3603                    expected_text[..end_ix].chars().rev().collect::<String>(),
3604                );
3605            }
3606
3607            for _ in 0..10 {
3608                let end_ix = rng.gen_range(0..=text_rope.len());
3609                let start_ix = rng.gen_range(0..=end_ix);
3610                assert_eq!(
3611                    snapshot
3612                        .bytes_in_range(start_ix..end_ix)
3613                        .flatten()
3614                        .copied()
3615                        .collect::<Vec<_>>(),
3616                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3617                    "bytes_in_range({:?})",
3618                    start_ix..end_ix,
3619                );
3620            }
3621        }
3622
3623        let snapshot = multibuffer.read(cx).snapshot(cx);
3624        for (old_snapshot, subscription) in old_versions {
3625            let edits = subscription.consume().into_inner();
3626
3627            log::info!(
3628                "applying subscription edits to old text: {:?}: {:?}",
3629                old_snapshot.text(),
3630                edits,
3631            );
3632
3633            let mut text = old_snapshot.text();
3634            for edit in edits {
3635                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3636                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3637            }
3638            assert_eq!(text.to_string(), snapshot.text());
3639        }
3640    }
3641
3642    #[gpui::test]
3643    fn test_history(cx: &mut MutableAppContext) {
3644        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3645        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3646        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3647        let group_interval = multibuffer.read(cx).history.group_interval;
3648        multibuffer.update(cx, |multibuffer, cx| {
3649            multibuffer.push_excerpts(buffer_1.clone(), [0..buffer_1.read(cx).len()], cx);
3650            multibuffer.push_excerpts(buffer_2.clone(), [0..buffer_2.read(cx).len()], cx);
3651        });
3652
3653        let mut now = Instant::now();
3654
3655        multibuffer.update(cx, |multibuffer, cx| {
3656            multibuffer.start_transaction_at(now, cx);
3657            multibuffer.edit(
3658                [
3659                    Point::new(0, 0)..Point::new(0, 0),
3660                    Point::new(1, 0)..Point::new(1, 0),
3661                ],
3662                "A",
3663                cx,
3664            );
3665            multibuffer.edit(
3666                [
3667                    Point::new(0, 1)..Point::new(0, 1),
3668                    Point::new(1, 1)..Point::new(1, 1),
3669                ],
3670                "B",
3671                cx,
3672            );
3673            multibuffer.end_transaction_at(now, cx);
3674            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3675
3676            now += 2 * group_interval;
3677            multibuffer.start_transaction_at(now, cx);
3678            multibuffer.edit([2..2], "C", cx);
3679            multibuffer.end_transaction_at(now, cx);
3680            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3681
3682            multibuffer.undo(cx);
3683            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3684
3685            multibuffer.undo(cx);
3686            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3687
3688            multibuffer.redo(cx);
3689            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3690
3691            multibuffer.redo(cx);
3692            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3693
3694            buffer_1.update(cx, |buffer_1, cx| buffer_1.undo(cx));
3695            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3696
3697            multibuffer.undo(cx);
3698            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3699
3700            multibuffer.redo(cx);
3701            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3702
3703            multibuffer.redo(cx);
3704            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3705
3706            multibuffer.undo(cx);
3707            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3708
3709            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3710            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3711
3712            multibuffer.undo(cx);
3713            assert_eq!(multibuffer.read(cx).text(), "C1234\n5678");
3714        });
3715    }
3716}