multi_buffer.rs

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