multi_buffer.rs

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