multi_buffer.rs

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