multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::{anyhow, Result};
   5use clock::ReplicaId;
   6use collections::{BTreeMap, Bound, HashMap, HashSet};
   7use futures::{channel::mpsc, SinkExt};
   8use git::diff::DiffHunk;
   9use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
  10pub use language::Completion;
  11use language::{
  12    char_kind, AutoindentMode, Buffer, BufferChunks, BufferSnapshot, CharKind, Chunk, CursorShape,
  13    DiagnosticEntry, File, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16,
  14    Outline, OutlineItem, Point, PointUtf16, Selection, TextDimension, ToOffset as _,
  15    ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _, TransactionId, Unclipped,
  16};
  17use std::{
  18    borrow::Cow,
  19    cell::{Ref, RefCell},
  20    cmp, fmt,
  21    future::Future,
  22    io,
  23    iter::{self, FromIterator},
  24    mem,
  25    ops::{Range, RangeBounds, Sub},
  26    str,
  27    sync::Arc,
  28    time::{Duration, Instant},
  29};
  30use sum_tree::{Bias, Cursor, SumTree};
  31use text::{
  32    locator::Locator,
  33    subscription::{Subscription, Topic},
  34    Edit, TextSummary,
  35};
  36use theme::SyntaxTheme;
  37use util::post_inc;
  38
  39const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  40
  41#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  42pub struct ExcerptId(usize);
  43
  44pub struct MultiBuffer {
  45    snapshot: RefCell<MultiBufferSnapshot>,
  46    buffers: RefCell<HashMap<u64, BufferState>>,
  47    next_excerpt_id: usize,
  48    subscriptions: Topic,
  49    singleton: bool,
  50    replica_id: ReplicaId,
  51    history: History,
  52    title: Option<String>,
  53}
  54
  55#[derive(Clone, Debug, PartialEq, Eq)]
  56pub enum Event {
  57    ExcerptsAdded {
  58        buffer: ModelHandle<Buffer>,
  59        predecessor: ExcerptId,
  60        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  61    },
  62    ExcerptsRemoved {
  63        ids: Vec<ExcerptId>,
  64    },
  65    Edited,
  66    Reloaded,
  67    LanguageChanged,
  68    Reparsed,
  69    Saved,
  70    FileHandleChanged,
  71    Closed,
  72    DirtyChanged,
  73    DiagnosticsUpdated,
  74}
  75
  76#[derive(Clone)]
  77struct History {
  78    next_transaction_id: TransactionId,
  79    undo_stack: Vec<Transaction>,
  80    redo_stack: Vec<Transaction>,
  81    transaction_depth: usize,
  82    group_interval: Duration,
  83}
  84
  85#[derive(Clone)]
  86struct Transaction {
  87    id: TransactionId,
  88    buffer_transactions: HashMap<u64, text::TransactionId>,
  89    first_edit_at: Instant,
  90    last_edit_at: Instant,
  91    suppress_grouping: bool,
  92}
  93
  94pub trait ToOffset: 'static + fmt::Debug {
  95    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  96}
  97
  98pub trait ToOffsetUtf16: 'static + fmt::Debug {
  99    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 100}
 101
 102pub trait ToPoint: 'static + fmt::Debug {
 103    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 104}
 105
 106pub trait ToPointUtf16: 'static + fmt::Debug {
 107    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 108}
 109
 110struct BufferState {
 111    buffer: ModelHandle<Buffer>,
 112    last_version: clock::Global,
 113    last_parse_count: usize,
 114    last_selections_update_count: usize,
 115    last_diagnostics_update_count: usize,
 116    last_file_update_count: usize,
 117    last_git_diff_update_count: usize,
 118    excerpts: Vec<Locator>,
 119    _subscriptions: [gpui::Subscription; 2],
 120}
 121
 122#[derive(Clone, Default)]
 123pub struct MultiBufferSnapshot {
 124    singleton: bool,
 125    excerpts: SumTree<Excerpt>,
 126    excerpt_ids: SumTree<ExcerptIdMapping>,
 127    parse_count: usize,
 128    diagnostics_update_count: usize,
 129    trailing_excerpt_update_count: usize,
 130    git_diff_update_count: usize,
 131    edit_count: usize,
 132    is_dirty: bool,
 133    has_conflict: bool,
 134}
 135
 136pub struct ExcerptBoundary {
 137    pub id: ExcerptId,
 138    pub row: u32,
 139    pub buffer: BufferSnapshot,
 140    pub range: ExcerptRange<text::Anchor>,
 141    pub starts_new_buffer: bool,
 142}
 143
 144#[derive(Clone)]
 145struct Excerpt {
 146    id: ExcerptId,
 147    locator: Locator,
 148    buffer_id: u64,
 149    buffer: BufferSnapshot,
 150    range: ExcerptRange<text::Anchor>,
 151    max_buffer_row: u32,
 152    text_summary: TextSummary,
 153    has_trailing_newline: bool,
 154}
 155
 156#[derive(Clone, Debug)]
 157struct ExcerptIdMapping {
 158    id: ExcerptId,
 159    locator: Locator,
 160}
 161
 162#[derive(Clone, Debug, Eq, PartialEq)]
 163pub struct ExcerptRange<T> {
 164    pub context: Range<T>,
 165    pub primary: Option<Range<T>>,
 166}
 167
 168#[derive(Clone, Debug, Default)]
 169struct ExcerptSummary {
 170    excerpt_id: ExcerptId,
 171    excerpt_locator: Locator,
 172    max_buffer_row: u32,
 173    text: TextSummary,
 174}
 175
 176#[derive(Clone)]
 177pub struct MultiBufferRows<'a> {
 178    buffer_row_range: Range<u32>,
 179    excerpts: Cursor<'a, Excerpt, Point>,
 180}
 181
 182pub struct MultiBufferChunks<'a> {
 183    range: Range<usize>,
 184    excerpts: Cursor<'a, Excerpt, usize>,
 185    excerpt_chunks: Option<ExcerptChunks<'a>>,
 186    language_aware: bool,
 187}
 188
 189pub struct MultiBufferBytes<'a> {
 190    range: Range<usize>,
 191    excerpts: Cursor<'a, Excerpt, usize>,
 192    excerpt_bytes: Option<ExcerptBytes<'a>>,
 193    chunk: &'a [u8],
 194}
 195
 196struct ExcerptChunks<'a> {
 197    content_chunks: BufferChunks<'a>,
 198    footer_height: usize,
 199}
 200
 201struct ExcerptBytes<'a> {
 202    content_bytes: text::Bytes<'a>,
 203    footer_height: usize,
 204}
 205
 206impl MultiBuffer {
 207    pub fn new(replica_id: ReplicaId) -> Self {
 208        Self {
 209            snapshot: Default::default(),
 210            buffers: Default::default(),
 211            next_excerpt_id: 1,
 212            subscriptions: Default::default(),
 213            singleton: false,
 214            replica_id,
 215            history: History {
 216                next_transaction_id: Default::default(),
 217                undo_stack: Default::default(),
 218                redo_stack: Default::default(),
 219                transaction_depth: 0,
 220                group_interval: Duration::from_millis(300),
 221            },
 222            title: Default::default(),
 223        }
 224    }
 225
 226    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 227        let mut buffers = HashMap::default();
 228        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 229            buffers.insert(
 230                *buffer_id,
 231                BufferState {
 232                    buffer: buffer_state.buffer.clone(),
 233                    last_version: buffer_state.last_version.clone(),
 234                    last_parse_count: buffer_state.last_parse_count,
 235                    last_selections_update_count: buffer_state.last_selections_update_count,
 236                    last_diagnostics_update_count: buffer_state.last_diagnostics_update_count,
 237                    last_file_update_count: buffer_state.last_file_update_count,
 238                    last_git_diff_update_count: buffer_state.last_git_diff_update_count,
 239                    excerpts: buffer_state.excerpts.clone(),
 240                    _subscriptions: [
 241                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 242                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 243                    ],
 244                },
 245            );
 246        }
 247        Self {
 248            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 249            buffers: RefCell::new(buffers),
 250            next_excerpt_id: 1,
 251            subscriptions: Default::default(),
 252            singleton: self.singleton,
 253            replica_id: self.replica_id,
 254            history: self.history.clone(),
 255            title: self.title.clone(),
 256        }
 257    }
 258
 259    pub fn with_title(mut self, title: String) -> Self {
 260        self.title = Some(title);
 261        self
 262    }
 263
 264    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 265        let mut this = Self::new(buffer.read(cx).replica_id());
 266        this.singleton = true;
 267        this.push_excerpts(
 268            buffer,
 269            [ExcerptRange {
 270                context: text::Anchor::MIN..text::Anchor::MAX,
 271                primary: None,
 272            }],
 273            cx,
 274        );
 275        this.snapshot.borrow_mut().singleton = true;
 276        this
 277    }
 278
 279    pub fn replica_id(&self) -> ReplicaId {
 280        self.replica_id
 281    }
 282
 283    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 284        self.sync(cx);
 285        self.snapshot.borrow().clone()
 286    }
 287
 288    pub(crate) fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 289        self.sync(cx);
 290        self.snapshot.borrow()
 291    }
 292
 293    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 294        if self.singleton {
 295            return Some(
 296                self.buffers
 297                    .borrow()
 298                    .values()
 299                    .next()
 300                    .unwrap()
 301                    .buffer
 302                    .clone(),
 303            );
 304        } else {
 305            None
 306        }
 307    }
 308
 309    pub fn is_singleton(&self) -> bool {
 310        self.singleton
 311    }
 312
 313    pub fn subscribe(&mut self) -> Subscription {
 314        self.subscriptions.subscribe()
 315    }
 316
 317    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 318        self.read(cx).is_dirty()
 319    }
 320
 321    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 322        self.read(cx).has_conflict()
 323    }
 324
 325    // The `is_empty` signature doesn't match what clippy expects
 326    #[allow(clippy::len_without_is_empty)]
 327    pub fn len(&self, cx: &AppContext) -> usize {
 328        self.read(cx).len()
 329    }
 330
 331    pub fn is_empty(&self, cx: &AppContext) -> bool {
 332        self.len(cx) != 0
 333    }
 334
 335    pub fn symbols_containing<T: ToOffset>(
 336        &self,
 337        offset: T,
 338        theme: Option<&SyntaxTheme>,
 339        cx: &AppContext,
 340    ) -> Option<(u64, Vec<OutlineItem<Anchor>>)> {
 341        self.read(cx).symbols_containing(offset, theme)
 342    }
 343
 344    pub fn git_diff_recalc(&mut self, cx: &mut ModelContext<Self>) {
 345        let buffers = self.buffers.borrow();
 346        for buffer_state in buffers.values() {
 347            if buffer_state.buffer.read(cx).needs_git_diff_recalc() {
 348                buffer_state
 349                    .buffer
 350                    .update(cx, |buffer, cx| buffer.git_diff_recalc(cx))
 351            }
 352        }
 353    }
 354
 355    pub fn edit<I, S, T>(
 356        &mut self,
 357        edits: I,
 358        mut autoindent_mode: Option<AutoindentMode>,
 359        cx: &mut ModelContext<Self>,
 360    ) where
 361        I: IntoIterator<Item = (Range<S>, T)>,
 362        S: ToOffset,
 363        T: Into<Arc<str>>,
 364    {
 365        if self.buffers.borrow().is_empty() {
 366            return;
 367        }
 368
 369        let snapshot = self.read(cx);
 370        let edits = edits.into_iter().map(|(range, new_text)| {
 371            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 372            if range.start > range.end {
 373                mem::swap(&mut range.start, &mut range.end);
 374            }
 375            (range, new_text)
 376        });
 377
 378        if let Some(buffer) = self.as_singleton() {
 379            return buffer.update(cx, |buffer, cx| {
 380                buffer.edit(edits, autoindent_mode, cx);
 381            });
 382        }
 383
 384        let original_indent_columns = match &mut autoindent_mode {
 385            Some(AutoindentMode::Block {
 386                original_indent_columns,
 387            }) => mem::take(original_indent_columns),
 388            _ => Default::default(),
 389        };
 390
 391        struct BufferEdit {
 392            range: Range<usize>,
 393            new_text: Arc<str>,
 394            is_insertion: bool,
 395            original_indent_column: u32,
 396        }
 397        let mut buffer_edits: HashMap<u64, Vec<BufferEdit>> = Default::default();
 398        let mut cursor = snapshot.excerpts.cursor::<usize>();
 399        for (ix, (range, new_text)) in edits.enumerate() {
 400            let new_text: Arc<str> = new_text.into();
 401            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 402            cursor.seek(&range.start, Bias::Right, &());
 403            if cursor.item().is_none() && range.start == *cursor.start() {
 404                cursor.prev(&());
 405            }
 406            let start_excerpt = cursor.item().expect("start offset out of bounds");
 407            let start_overshoot = range.start - cursor.start();
 408            let buffer_start = start_excerpt
 409                .range
 410                .context
 411                .start
 412                .to_offset(&start_excerpt.buffer)
 413                + start_overshoot;
 414
 415            cursor.seek(&range.end, Bias::Right, &());
 416            if cursor.item().is_none() && range.end == *cursor.start() {
 417                cursor.prev(&());
 418            }
 419            let end_excerpt = cursor.item().expect("end offset out of bounds");
 420            let end_overshoot = range.end - cursor.start();
 421            let buffer_end = end_excerpt
 422                .range
 423                .context
 424                .start
 425                .to_offset(&end_excerpt.buffer)
 426                + end_overshoot;
 427
 428            if start_excerpt.id == end_excerpt.id {
 429                buffer_edits
 430                    .entry(start_excerpt.buffer_id)
 431                    .or_insert(Vec::new())
 432                    .push(BufferEdit {
 433                        range: buffer_start..buffer_end,
 434                        new_text,
 435                        is_insertion: true,
 436                        original_indent_column,
 437                    });
 438            } else {
 439                let start_excerpt_range = buffer_start
 440                    ..start_excerpt
 441                        .range
 442                        .context
 443                        .end
 444                        .to_offset(&start_excerpt.buffer);
 445                let end_excerpt_range = end_excerpt
 446                    .range
 447                    .context
 448                    .start
 449                    .to_offset(&end_excerpt.buffer)
 450                    ..buffer_end;
 451                buffer_edits
 452                    .entry(start_excerpt.buffer_id)
 453                    .or_insert(Vec::new())
 454                    .push(BufferEdit {
 455                        range: start_excerpt_range,
 456                        new_text: new_text.clone(),
 457                        is_insertion: true,
 458                        original_indent_column,
 459                    });
 460                buffer_edits
 461                    .entry(end_excerpt.buffer_id)
 462                    .or_insert(Vec::new())
 463                    .push(BufferEdit {
 464                        range: end_excerpt_range,
 465                        new_text: new_text.clone(),
 466                        is_insertion: false,
 467                        original_indent_column,
 468                    });
 469
 470                cursor.seek(&range.start, Bias::Right, &());
 471                cursor.next(&());
 472                while let Some(excerpt) = cursor.item() {
 473                    if excerpt.id == end_excerpt.id {
 474                        break;
 475                    }
 476                    buffer_edits
 477                        .entry(excerpt.buffer_id)
 478                        .or_insert(Vec::new())
 479                        .push(BufferEdit {
 480                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 481                            new_text: new_text.clone(),
 482                            is_insertion: false,
 483                            original_indent_column,
 484                        });
 485                    cursor.next(&());
 486                }
 487            }
 488        }
 489
 490        for (buffer_id, mut edits) in buffer_edits {
 491            edits.sort_unstable_by_key(|edit| edit.range.start);
 492            self.buffers.borrow()[&buffer_id]
 493                .buffer
 494                .update(cx, |buffer, cx| {
 495                    let mut edits = edits.into_iter().peekable();
 496                    let mut insertions = Vec::new();
 497                    let mut original_indent_columns = Vec::new();
 498                    let mut deletions = Vec::new();
 499                    let empty_str: Arc<str> = "".into();
 500                    while let Some(BufferEdit {
 501                        mut range,
 502                        new_text,
 503                        mut is_insertion,
 504                        original_indent_column,
 505                    }) = edits.next()
 506                    {
 507                        while let Some(BufferEdit {
 508                            range: next_range,
 509                            is_insertion: next_is_insertion,
 510                            ..
 511                        }) = edits.peek()
 512                        {
 513                            if range.end >= next_range.start {
 514                                range.end = cmp::max(next_range.end, range.end);
 515                                is_insertion |= *next_is_insertion;
 516                                edits.next();
 517                            } else {
 518                                break;
 519                            }
 520                        }
 521
 522                        if is_insertion {
 523                            original_indent_columns.push(original_indent_column);
 524                            insertions.push((
 525                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 526                                new_text.clone(),
 527                            ));
 528                        } else if !range.is_empty() {
 529                            deletions.push((
 530                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 531                                empty_str.clone(),
 532                            ));
 533                        }
 534                    }
 535
 536                    let deletion_autoindent_mode =
 537                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 538                            Some(AutoindentMode::Block {
 539                                original_indent_columns: Default::default(),
 540                            })
 541                        } else {
 542                            None
 543                        };
 544                    let insertion_autoindent_mode =
 545                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 546                            Some(AutoindentMode::Block {
 547                                original_indent_columns,
 548                            })
 549                        } else {
 550                            None
 551                        };
 552
 553                    buffer.edit(deletions, deletion_autoindent_mode, cx);
 554                    buffer.edit(insertions, insertion_autoindent_mode, cx);
 555                })
 556        }
 557    }
 558
 559    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 560        self.start_transaction_at(Instant::now(), cx)
 561    }
 562
 563    pub(crate) fn start_transaction_at(
 564        &mut self,
 565        now: Instant,
 566        cx: &mut ModelContext<Self>,
 567    ) -> Option<TransactionId> {
 568        if let Some(buffer) = self.as_singleton() {
 569            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 570        }
 571
 572        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 573            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 574        }
 575        self.history.start_transaction(now)
 576    }
 577
 578    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 579        self.end_transaction_at(Instant::now(), cx)
 580    }
 581
 582    pub(crate) fn end_transaction_at(
 583        &mut self,
 584        now: Instant,
 585        cx: &mut ModelContext<Self>,
 586    ) -> Option<TransactionId> {
 587        if let Some(buffer) = self.as_singleton() {
 588            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 589        }
 590
 591        let mut buffer_transactions = HashMap::default();
 592        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 593            if let Some(transaction_id) =
 594                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 595            {
 596                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 597            }
 598        }
 599
 600        if self.history.end_transaction(now, buffer_transactions) {
 601            let transaction_id = self.history.group().unwrap();
 602            Some(transaction_id)
 603        } else {
 604            None
 605        }
 606    }
 607
 608    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 609        self.history.finalize_last_transaction();
 610        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 611            buffer.update(cx, |buffer, _| {
 612                buffer.finalize_last_transaction();
 613            });
 614        }
 615    }
 616
 617    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &mut ModelContext<Self>)
 618    where
 619        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
 620    {
 621        self.history
 622            .push_transaction(buffer_transactions, Instant::now(), cx);
 623        self.history.finalize_last_transaction();
 624    }
 625
 626    pub fn group_until_transaction(
 627        &mut self,
 628        transaction_id: TransactionId,
 629        cx: &mut ModelContext<Self>,
 630    ) {
 631        if let Some(buffer) = self.as_singleton() {
 632            buffer.update(cx, |buffer, _| {
 633                buffer.group_until_transaction(transaction_id)
 634            });
 635        } else {
 636            self.history.group_until(transaction_id);
 637        }
 638    }
 639
 640    pub fn set_active_selections(
 641        &mut self,
 642        selections: &[Selection<Anchor>],
 643        line_mode: bool,
 644        cursor_shape: CursorShape,
 645        cx: &mut ModelContext<Self>,
 646    ) {
 647        let mut selections_by_buffer: HashMap<u64, Vec<Selection<text::Anchor>>> =
 648            Default::default();
 649        let snapshot = self.read(cx);
 650        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
 651        for selection in selections {
 652            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 653            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 654
 655            cursor.seek(&Some(start_locator), Bias::Left, &());
 656            while let Some(excerpt) = cursor.item() {
 657                if excerpt.locator > *end_locator {
 658                    break;
 659                }
 660
 661                let mut start = excerpt.range.context.start;
 662                let mut end = excerpt.range.context.end;
 663                if excerpt.id == selection.start.excerpt_id {
 664                    start = selection.start.text_anchor;
 665                }
 666                if excerpt.id == selection.end.excerpt_id {
 667                    end = selection.end.text_anchor;
 668                }
 669                selections_by_buffer
 670                    .entry(excerpt.buffer_id)
 671                    .or_default()
 672                    .push(Selection {
 673                        id: selection.id,
 674                        start,
 675                        end,
 676                        reversed: selection.reversed,
 677                        goal: selection.goal,
 678                    });
 679
 680                cursor.next(&());
 681            }
 682        }
 683
 684        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 685            if !selections_by_buffer.contains_key(buffer_id) {
 686                buffer_state
 687                    .buffer
 688                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 689            }
 690        }
 691
 692        for (buffer_id, mut selections) in selections_by_buffer {
 693            self.buffers.borrow()[&buffer_id]
 694                .buffer
 695                .update(cx, |buffer, cx| {
 696                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
 697                    let mut selections = selections.into_iter().peekable();
 698                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 699                        let mut selection = selections.next()?;
 700                        while let Some(next_selection) = selections.peek() {
 701                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
 702                                let next_selection = selections.next().unwrap();
 703                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
 704                                    selection.end = next_selection.end;
 705                                }
 706                            } else {
 707                                break;
 708                            }
 709                        }
 710                        Some(selection)
 711                    }));
 712                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
 713                });
 714        }
 715    }
 716
 717    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 718        for buffer in self.buffers.borrow().values() {
 719            buffer
 720                .buffer
 721                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 722        }
 723    }
 724
 725    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 726        if let Some(buffer) = self.as_singleton() {
 727            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 728        }
 729
 730        while let Some(transaction) = self.history.pop_undo() {
 731            let mut undone = false;
 732            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 733                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 734                    undone |= buffer.update(cx, |buffer, cx| {
 735                        let undo_to = *buffer_transaction_id;
 736                        if let Some(entry) = buffer.peek_undo_stack() {
 737                            *buffer_transaction_id = entry.transaction_id();
 738                        }
 739                        buffer.undo_to_transaction(undo_to, cx)
 740                    });
 741                }
 742            }
 743
 744            if undone {
 745                return Some(transaction.id);
 746            }
 747        }
 748
 749        None
 750    }
 751
 752    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 753        if let Some(buffer) = self.as_singleton() {
 754            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 755        }
 756
 757        while let Some(transaction) = self.history.pop_redo() {
 758            let mut redone = false;
 759            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 760                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 761                    redone |= buffer.update(cx, |buffer, cx| {
 762                        let redo_to = *buffer_transaction_id;
 763                        if let Some(entry) = buffer.peek_redo_stack() {
 764                            *buffer_transaction_id = entry.transaction_id();
 765                        }
 766                        buffer.redo_to_transaction(redo_to, cx)
 767                    });
 768                }
 769            }
 770
 771            if redone {
 772                return Some(transaction.id);
 773            }
 774        }
 775
 776        None
 777    }
 778
 779    pub fn stream_excerpts_with_context_lines(
 780        &mut self,
 781        excerpts: Vec<(ModelHandle<Buffer>, Vec<Range<text::Anchor>>)>,
 782        context_line_count: u32,
 783        cx: &mut ModelContext<Self>,
 784    ) -> (Task<()>, mpsc::Receiver<Range<Anchor>>) {
 785        let (mut tx, rx) = mpsc::channel(256);
 786        let task = cx.spawn(|this, mut cx| async move {
 787            for (buffer, ranges) in excerpts {
 788                let (buffer_id, buffer_snapshot) =
 789                    buffer.read_with(&cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
 790
 791                let mut excerpt_ranges = Vec::new();
 792                let mut range_counts = Vec::new();
 793                cx.background()
 794                    .scoped(|scope| {
 795                        scope.spawn(async {
 796                            let (ranges, counts) =
 797                                build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 798                            excerpt_ranges = ranges;
 799                            range_counts = counts;
 800                        });
 801                    })
 802                    .await;
 803
 804                let mut ranges = ranges.into_iter();
 805                let mut range_counts = range_counts.into_iter();
 806                for excerpt_ranges in excerpt_ranges.chunks(100) {
 807                    let excerpt_ids = this.update(&mut cx, |this, cx| {
 808                        this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
 809                    });
 810
 811                    for (excerpt_id, range_count) in
 812                        excerpt_ids.into_iter().zip(range_counts.by_ref())
 813                    {
 814                        for range in ranges.by_ref().take(range_count) {
 815                            let start = Anchor {
 816                                buffer_id: Some(buffer_id),
 817                                excerpt_id: excerpt_id.clone(),
 818                                text_anchor: range.start,
 819                            };
 820                            let end = Anchor {
 821                                buffer_id: Some(buffer_id),
 822                                excerpt_id: excerpt_id.clone(),
 823                                text_anchor: range.end,
 824                            };
 825                            if tx.send(start..end).await.is_err() {
 826                                break;
 827                            }
 828                        }
 829                    }
 830                }
 831            }
 832        });
 833        (task, rx)
 834    }
 835
 836    pub fn push_excerpts<O>(
 837        &mut self,
 838        buffer: ModelHandle<Buffer>,
 839        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
 840        cx: &mut ModelContext<Self>,
 841    ) -> Vec<ExcerptId>
 842    where
 843        O: text::ToOffset,
 844    {
 845        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
 846    }
 847
 848    pub fn push_excerpts_with_context_lines<O>(
 849        &mut self,
 850        buffer: ModelHandle<Buffer>,
 851        ranges: Vec<Range<O>>,
 852        context_line_count: u32,
 853        cx: &mut ModelContext<Self>,
 854    ) -> Vec<Range<Anchor>>
 855    where
 856        O: text::ToPoint + text::ToOffset,
 857    {
 858        let buffer_id = buffer.read(cx).remote_id();
 859        let buffer_snapshot = buffer.read(cx).snapshot();
 860        let (excerpt_ranges, range_counts) =
 861            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 862
 863        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
 864
 865        let mut anchor_ranges = Vec::new();
 866        let mut ranges = ranges.into_iter();
 867        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
 868            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
 869                let start = Anchor {
 870                    buffer_id: Some(buffer_id),
 871                    excerpt_id: excerpt_id.clone(),
 872                    text_anchor: buffer_snapshot.anchor_after(range.start),
 873                };
 874                let end = Anchor {
 875                    buffer_id: Some(buffer_id),
 876                    excerpt_id: excerpt_id.clone(),
 877                    text_anchor: buffer_snapshot.anchor_after(range.end),
 878                };
 879                start..end
 880            }))
 881        }
 882        anchor_ranges
 883    }
 884
 885    pub fn insert_excerpts_after<O>(
 886        &mut self,
 887        prev_excerpt_id: ExcerptId,
 888        buffer: ModelHandle<Buffer>,
 889        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
 890        cx: &mut ModelContext<Self>,
 891    ) -> Vec<ExcerptId>
 892    where
 893        O: text::ToOffset,
 894    {
 895        let mut ids = Vec::new();
 896        let mut next_excerpt_id = self.next_excerpt_id;
 897        self.insert_excerpts_with_ids_after(
 898            prev_excerpt_id,
 899            buffer,
 900            ranges.into_iter().map(|range| {
 901                let id = ExcerptId(post_inc(&mut next_excerpt_id));
 902                ids.push(id);
 903                (id, range)
 904            }),
 905            cx,
 906        );
 907        ids
 908    }
 909
 910    pub fn insert_excerpts_with_ids_after<O>(
 911        &mut self,
 912        prev_excerpt_id: ExcerptId,
 913        buffer: ModelHandle<Buffer>,
 914        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
 915        cx: &mut ModelContext<Self>,
 916    ) where
 917        O: text::ToOffset,
 918    {
 919        assert_eq!(self.history.transaction_depth, 0);
 920        let mut ranges = ranges.into_iter().peekable();
 921        if ranges.peek().is_none() {
 922            return Default::default();
 923        }
 924
 925        self.sync(cx);
 926
 927        let buffer_id = buffer.read(cx).remote_id();
 928        let buffer_snapshot = buffer.read(cx).snapshot();
 929
 930        let mut buffers = self.buffers.borrow_mut();
 931        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
 932            last_version: buffer_snapshot.version().clone(),
 933            last_parse_count: buffer_snapshot.parse_count(),
 934            last_selections_update_count: buffer_snapshot.selections_update_count(),
 935            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 936            last_file_update_count: buffer_snapshot.file_update_count(),
 937            last_git_diff_update_count: buffer_snapshot.git_diff_update_count(),
 938            excerpts: Default::default(),
 939            _subscriptions: [
 940                cx.observe(&buffer, |_, _, cx| cx.notify()),
 941                cx.subscribe(&buffer, Self::on_buffer_event),
 942            ],
 943            buffer: buffer.clone(),
 944        });
 945
 946        let mut snapshot = self.snapshot.borrow_mut();
 947
 948        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
 949        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
 950        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
 951        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
 952        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
 953
 954        let edit_start = new_excerpts.summary().text.len;
 955        new_excerpts.update_last(
 956            |excerpt| {
 957                excerpt.has_trailing_newline = true;
 958            },
 959            &(),
 960        );
 961
 962        let next_locator = if let Some(excerpt) = cursor.item() {
 963            excerpt.locator.clone()
 964        } else {
 965            Locator::max()
 966        };
 967
 968        let mut excerpts = Vec::new();
 969        while let Some((id, range)) = ranges.next() {
 970            let locator = Locator::between(&prev_locator, &next_locator);
 971            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
 972                buffer_state.excerpts.insert(ix, locator.clone());
 973            }
 974            let range = ExcerptRange {
 975                context: buffer_snapshot.anchor_before(&range.context.start)
 976                    ..buffer_snapshot.anchor_after(&range.context.end),
 977                primary: range.primary.map(|primary| {
 978                    buffer_snapshot.anchor_before(&primary.start)
 979                        ..buffer_snapshot.anchor_after(&primary.end)
 980                }),
 981            };
 982            if id.0 >= self.next_excerpt_id {
 983                self.next_excerpt_id = id.0 + 1;
 984            }
 985            excerpts.push((id, range.clone()));
 986            let excerpt = Excerpt::new(
 987                id,
 988                locator.clone(),
 989                buffer_id,
 990                buffer_snapshot.clone(),
 991                range,
 992                ranges.peek().is_some() || cursor.item().is_some(),
 993            );
 994            new_excerpts.push(excerpt, &());
 995            prev_locator = locator.clone();
 996            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
 997        }
 998
 999        let edit_end = new_excerpts.summary().text.len;
1000
1001        let suffix = cursor.suffix(&());
1002        let changed_trailing_excerpt = suffix.is_empty();
1003        new_excerpts.push_tree(suffix, &());
1004        drop(cursor);
1005        snapshot.excerpts = new_excerpts;
1006        snapshot.excerpt_ids = new_excerpt_ids;
1007        if changed_trailing_excerpt {
1008            snapshot.trailing_excerpt_update_count += 1;
1009        }
1010
1011        self.subscriptions.publish_mut([Edit {
1012            old: edit_start..edit_start,
1013            new: edit_start..edit_end,
1014        }]);
1015        cx.emit(Event::Edited);
1016        cx.emit(Event::ExcerptsAdded {
1017            buffer,
1018            predecessor: prev_excerpt_id,
1019            excerpts,
1020        });
1021        cx.notify();
1022    }
1023
1024    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1025        self.sync(cx);
1026        let ids = self.excerpt_ids();
1027        self.buffers.borrow_mut().clear();
1028        let mut snapshot = self.snapshot.borrow_mut();
1029        let prev_len = snapshot.len();
1030        snapshot.excerpts = Default::default();
1031        snapshot.trailing_excerpt_update_count += 1;
1032        snapshot.is_dirty = false;
1033        snapshot.has_conflict = false;
1034
1035        self.subscriptions.publish_mut([Edit {
1036            old: 0..prev_len,
1037            new: 0..0,
1038        }]);
1039        cx.emit(Event::Edited);
1040        cx.emit(Event::ExcerptsRemoved { ids });
1041        cx.notify();
1042    }
1043
1044    pub fn excerpts_for_buffer(
1045        &self,
1046        buffer: &ModelHandle<Buffer>,
1047        cx: &AppContext,
1048    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1049        let mut excerpts = Vec::new();
1050        let snapshot = self.read(cx);
1051        let buffers = self.buffers.borrow();
1052        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1053        for locator in buffers
1054            .get(&buffer.read(cx).remote_id())
1055            .map(|state| &state.excerpts)
1056            .into_iter()
1057            .flatten()
1058        {
1059            cursor.seek_forward(&Some(locator), Bias::Left, &());
1060            if let Some(excerpt) = cursor.item() {
1061                if excerpt.locator == *locator {
1062                    excerpts.push((excerpt.id.clone(), excerpt.range.clone()));
1063                }
1064            }
1065        }
1066
1067        excerpts
1068    }
1069
1070    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1071        self.snapshot
1072            .borrow()
1073            .excerpts
1074            .iter()
1075            .map(|entry| entry.id)
1076            .collect()
1077    }
1078
1079    pub fn excerpt_containing(
1080        &self,
1081        position: impl ToOffset,
1082        cx: &AppContext,
1083    ) -> Option<(ExcerptId, ModelHandle<Buffer>, Range<text::Anchor>)> {
1084        let snapshot = self.read(cx);
1085        let position = position.to_offset(&snapshot);
1086
1087        let mut cursor = snapshot.excerpts.cursor::<usize>();
1088        cursor.seek(&position, Bias::Right, &());
1089        cursor
1090            .item()
1091            .or_else(|| snapshot.excerpts.last())
1092            .map(|excerpt| {
1093                (
1094                    excerpt.id.clone(),
1095                    self.buffers
1096                        .borrow()
1097                        .get(&excerpt.buffer_id)
1098                        .unwrap()
1099                        .buffer
1100                        .clone(),
1101                    excerpt.range.context.clone(),
1102                )
1103            })
1104    }
1105
1106    // If point is at the end of the buffer, the last excerpt is returned
1107    pub fn point_to_buffer_offset<T: ToOffset>(
1108        &self,
1109        point: T,
1110        cx: &AppContext,
1111    ) -> Option<(ModelHandle<Buffer>, usize)> {
1112        let snapshot = self.read(cx);
1113        let offset = point.to_offset(&snapshot);
1114        let mut cursor = snapshot.excerpts.cursor::<usize>();
1115        cursor.seek(&offset, Bias::Right, &());
1116        if cursor.item().is_none() {
1117            cursor.prev(&());
1118        }
1119
1120        cursor.item().map(|excerpt| {
1121            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1122            let buffer_point = excerpt_start + offset - *cursor.start();
1123            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1124
1125            (buffer, buffer_point)
1126        })
1127    }
1128
1129    pub fn range_to_buffer_ranges<T: ToOffset>(
1130        &self,
1131        range: Range<T>,
1132        cx: &AppContext,
1133    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
1134        let snapshot = self.read(cx);
1135        let start = range.start.to_offset(&snapshot);
1136        let end = range.end.to_offset(&snapshot);
1137
1138        let mut result = Vec::new();
1139        let mut cursor = snapshot.excerpts.cursor::<usize>();
1140        cursor.seek(&start, Bias::Right, &());
1141        while let Some(excerpt) = cursor.item() {
1142            if *cursor.start() > end {
1143                break;
1144            }
1145
1146            let mut end_before_newline = cursor.end(&());
1147            if excerpt.has_trailing_newline {
1148                end_before_newline -= 1;
1149            }
1150            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1151            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1152            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1153            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1154            result.push((buffer, start..end));
1155            cursor.next(&());
1156        }
1157
1158        result
1159    }
1160
1161    pub fn remove_excerpts(
1162        &mut self,
1163        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1164        cx: &mut ModelContext<Self>,
1165    ) {
1166        self.sync(cx);
1167        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1168        if ids.is_empty() {
1169            return;
1170        }
1171
1172        let mut buffers = self.buffers.borrow_mut();
1173        let mut snapshot = self.snapshot.borrow_mut();
1174        let mut new_excerpts = SumTree::new();
1175        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1176        let mut edits = Vec::new();
1177        let mut excerpt_ids = ids.iter().copied().peekable();
1178
1179        while let Some(excerpt_id) = excerpt_ids.next() {
1180            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1181            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1182            new_excerpts.push_tree(cursor.slice(&Some(locator), Bias::Left, &()), &());
1183
1184            if let Some(mut excerpt) = cursor.item() {
1185                if excerpt.id != excerpt_id {
1186                    continue;
1187                }
1188                let mut old_start = cursor.start().1;
1189
1190                // Skip over the removed excerpt.
1191                'remove_excerpts: loop {
1192                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1193                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1194                        if buffer_state.excerpts.is_empty() {
1195                            buffers.remove(&excerpt.buffer_id);
1196                        }
1197                    }
1198                    cursor.next(&());
1199
1200                    // Skip over any subsequent excerpts that are also removed.
1201                    while let Some(&next_excerpt_id) = excerpt_ids.peek() {
1202                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1203                        if let Some(next_excerpt) = cursor.item() {
1204                            if next_excerpt.locator == *next_locator {
1205                                excerpt_ids.next();
1206                                excerpt = next_excerpt;
1207                                continue 'remove_excerpts;
1208                            }
1209                        }
1210                        break;
1211                    }
1212
1213                    break;
1214                }
1215
1216                // When removing the last excerpt, remove the trailing newline from
1217                // the previous excerpt.
1218                if cursor.item().is_none() && old_start > 0 {
1219                    old_start -= 1;
1220                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1221                }
1222
1223                // Push an edit for the removal of this run of excerpts.
1224                let old_end = cursor.start().1;
1225                let new_start = new_excerpts.summary().text.len;
1226                edits.push(Edit {
1227                    old: old_start..old_end,
1228                    new: new_start..new_start,
1229                });
1230            }
1231        }
1232        let suffix = cursor.suffix(&());
1233        let changed_trailing_excerpt = suffix.is_empty();
1234        new_excerpts.push_tree(suffix, &());
1235        drop(cursor);
1236        snapshot.excerpts = new_excerpts;
1237
1238        if changed_trailing_excerpt {
1239            snapshot.trailing_excerpt_update_count += 1;
1240        }
1241
1242        self.subscriptions.publish_mut(edits);
1243        cx.emit(Event::Edited);
1244        cx.emit(Event::ExcerptsRemoved { ids });
1245        cx.notify();
1246    }
1247
1248    pub fn wait_for_anchors<'a>(
1249        &self,
1250        anchors: impl 'a + Iterator<Item = Anchor>,
1251        cx: &mut ModelContext<Self>,
1252    ) -> impl 'static + Future<Output = Result<()>> {
1253        let borrow = self.buffers.borrow();
1254        let mut error = None;
1255        let mut futures = Vec::new();
1256        for anchor in anchors {
1257            if let Some(buffer_id) = anchor.buffer_id {
1258                if let Some(buffer) = borrow.get(&buffer_id) {
1259                    buffer.buffer.update(cx, |buffer, _| {
1260                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1261                    });
1262                } else {
1263                    error = Some(anyhow!(
1264                        "buffer {buffer_id} is not part of this multi-buffer"
1265                    ));
1266                    break;
1267                }
1268            }
1269        }
1270        async move {
1271            if let Some(error) = error {
1272                Err(error)?;
1273            }
1274            for future in futures {
1275                future.await?;
1276            }
1277            Ok(())
1278        }
1279    }
1280
1281    pub fn text_anchor_for_position<T: ToOffset>(
1282        &self,
1283        position: T,
1284        cx: &AppContext,
1285    ) -> Option<(ModelHandle<Buffer>, language::Anchor)> {
1286        let snapshot = self.read(cx);
1287        let anchor = snapshot.anchor_before(position);
1288        let buffer = self
1289            .buffers
1290            .borrow()
1291            .get(&anchor.buffer_id?)?
1292            .buffer
1293            .clone();
1294        Some((buffer, anchor.text_anchor))
1295    }
1296
1297    fn on_buffer_event(
1298        &mut self,
1299        _: ModelHandle<Buffer>,
1300        event: &language::Event,
1301        cx: &mut ModelContext<Self>,
1302    ) {
1303        cx.emit(match event {
1304            language::Event::Edited => Event::Edited,
1305            language::Event::DirtyChanged => Event::DirtyChanged,
1306            language::Event::Saved => Event::Saved,
1307            language::Event::FileHandleChanged => Event::FileHandleChanged,
1308            language::Event::Reloaded => Event::Reloaded,
1309            language::Event::LanguageChanged => Event::LanguageChanged,
1310            language::Event::Reparsed => Event::Reparsed,
1311            language::Event::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1312            language::Event::Closed => Event::Closed,
1313
1314            //
1315            language::Event::Operation(_) => return,
1316        });
1317    }
1318
1319    pub fn all_buffers(&self) -> HashSet<ModelHandle<Buffer>> {
1320        self.buffers
1321            .borrow()
1322            .values()
1323            .map(|state| state.buffer.clone())
1324            .collect()
1325    }
1326
1327    pub fn buffer(&self, buffer_id: u64) -> Option<ModelHandle<Buffer>> {
1328        self.buffers
1329            .borrow()
1330            .get(&buffer_id)
1331            .map(|state| state.buffer.clone())
1332    }
1333
1334    pub fn is_completion_trigger<T>(&self, position: T, text: &str, cx: &AppContext) -> bool
1335    where
1336        T: ToOffset,
1337    {
1338        let mut chars = text.chars();
1339        let char = if let Some(char) = chars.next() {
1340            char
1341        } else {
1342            return false;
1343        };
1344        if chars.next().is_some() {
1345            return false;
1346        }
1347
1348        if char.is_alphanumeric() || char == '_' {
1349            return true;
1350        }
1351
1352        let snapshot = self.snapshot(cx);
1353        let anchor = snapshot.anchor_before(position);
1354        anchor
1355            .buffer_id
1356            .and_then(|buffer_id| {
1357                let buffer = self.buffers.borrow().get(&buffer_id)?.buffer.clone();
1358                Some(
1359                    buffer
1360                        .read(cx)
1361                        .completion_triggers()
1362                        .iter()
1363                        .any(|string| string == text),
1364                )
1365            })
1366            .unwrap_or(false)
1367    }
1368
1369    pub fn language_at<'a, T: ToOffset>(
1370        &self,
1371        point: T,
1372        cx: &'a AppContext,
1373    ) -> Option<Arc<Language>> {
1374        self.point_to_buffer_offset(point, cx)
1375            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
1376    }
1377
1378    pub fn for_each_buffer(&self, mut f: impl FnMut(&ModelHandle<Buffer>)) {
1379        self.buffers
1380            .borrow()
1381            .values()
1382            .for_each(|state| f(&state.buffer))
1383    }
1384
1385    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1386        if let Some(title) = self.title.as_ref() {
1387            return title.into();
1388        }
1389
1390        if let Some(buffer) = self.as_singleton() {
1391            if let Some(file) = buffer.read(cx).file() {
1392                return file.file_name(cx).to_string_lossy();
1393            }
1394        }
1395
1396        "untitled".into()
1397    }
1398
1399    #[cfg(test)]
1400    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1401        self.as_singleton().unwrap().read(cx).is_parsing()
1402    }
1403
1404    fn sync(&self, cx: &AppContext) {
1405        let mut snapshot = self.snapshot.borrow_mut();
1406        let mut excerpts_to_edit = Vec::new();
1407        let mut reparsed = false;
1408        let mut diagnostics_updated = false;
1409        let mut git_diff_updated = false;
1410        let mut is_dirty = false;
1411        let mut has_conflict = false;
1412        let mut edited = false;
1413        let mut buffers = self.buffers.borrow_mut();
1414        for buffer_state in buffers.values_mut() {
1415            let buffer = buffer_state.buffer.read(cx);
1416            let version = buffer.version();
1417            let parse_count = buffer.parse_count();
1418            let selections_update_count = buffer.selections_update_count();
1419            let diagnostics_update_count = buffer.diagnostics_update_count();
1420            let file_update_count = buffer.file_update_count();
1421            let git_diff_update_count = buffer.git_diff_update_count();
1422
1423            let buffer_edited = version.changed_since(&buffer_state.last_version);
1424            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1425            let buffer_selections_updated =
1426                selections_update_count > buffer_state.last_selections_update_count;
1427            let buffer_diagnostics_updated =
1428                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1429            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1430            let buffer_git_diff_updated =
1431                git_diff_update_count > buffer_state.last_git_diff_update_count;
1432            if buffer_edited
1433                || buffer_reparsed
1434                || buffer_selections_updated
1435                || buffer_diagnostics_updated
1436                || buffer_file_updated
1437                || buffer_git_diff_updated
1438            {
1439                buffer_state.last_version = version;
1440                buffer_state.last_parse_count = parse_count;
1441                buffer_state.last_selections_update_count = selections_update_count;
1442                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1443                buffer_state.last_file_update_count = file_update_count;
1444                buffer_state.last_git_diff_update_count = git_diff_update_count;
1445                excerpts_to_edit.extend(
1446                    buffer_state
1447                        .excerpts
1448                        .iter()
1449                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
1450                );
1451            }
1452
1453            edited |= buffer_edited;
1454            reparsed |= buffer_reparsed;
1455            diagnostics_updated |= buffer_diagnostics_updated;
1456            git_diff_updated |= buffer_git_diff_updated;
1457            is_dirty |= buffer.is_dirty();
1458            has_conflict |= buffer.has_conflict();
1459        }
1460        if edited {
1461            snapshot.edit_count += 1;
1462        }
1463        if reparsed {
1464            snapshot.parse_count += 1;
1465        }
1466        if diagnostics_updated {
1467            snapshot.diagnostics_update_count += 1;
1468        }
1469        if git_diff_updated {
1470            snapshot.git_diff_update_count += 1;
1471        }
1472        snapshot.is_dirty = is_dirty;
1473        snapshot.has_conflict = has_conflict;
1474
1475        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
1476
1477        let mut edits = Vec::new();
1478        let mut new_excerpts = SumTree::new();
1479        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1480
1481        for (locator, buffer, buffer_edited) in excerpts_to_edit {
1482            new_excerpts.push_tree(cursor.slice(&Some(locator), Bias::Left, &()), &());
1483            let old_excerpt = cursor.item().unwrap();
1484            let buffer = buffer.read(cx);
1485            let buffer_id = buffer.remote_id();
1486
1487            let mut new_excerpt;
1488            if buffer_edited {
1489                edits.extend(
1490                    buffer
1491                        .edits_since_in_range::<usize>(
1492                            old_excerpt.buffer.version(),
1493                            old_excerpt.range.context.clone(),
1494                        )
1495                        .map(|mut edit| {
1496                            let excerpt_old_start = cursor.start().1;
1497                            let excerpt_new_start = new_excerpts.summary().text.len;
1498                            edit.old.start += excerpt_old_start;
1499                            edit.old.end += excerpt_old_start;
1500                            edit.new.start += excerpt_new_start;
1501                            edit.new.end += excerpt_new_start;
1502                            edit
1503                        }),
1504                );
1505
1506                new_excerpt = Excerpt::new(
1507                    old_excerpt.id,
1508                    locator.clone(),
1509                    buffer_id,
1510                    buffer.snapshot(),
1511                    old_excerpt.range.clone(),
1512                    old_excerpt.has_trailing_newline,
1513                );
1514            } else {
1515                new_excerpt = old_excerpt.clone();
1516                new_excerpt.buffer = buffer.snapshot();
1517            }
1518
1519            new_excerpts.push(new_excerpt, &());
1520            cursor.next(&());
1521        }
1522        new_excerpts.push_tree(cursor.suffix(&()), &());
1523
1524        drop(cursor);
1525        snapshot.excerpts = new_excerpts;
1526
1527        self.subscriptions.publish(edits);
1528    }
1529}
1530
1531#[cfg(any(test, feature = "test-support"))]
1532impl MultiBuffer {
1533    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> ModelHandle<Self> {
1534        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
1535        cx.add_model(|cx| Self::singleton(buffer, cx))
1536    }
1537
1538    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> ModelHandle<Self> {
1539        cx.add_model(|cx| {
1540            let mut multibuffer = MultiBuffer::new(0);
1541            let mutation_count = rng.gen_range(1..=5);
1542            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
1543            multibuffer
1544        })
1545    }
1546
1547    pub fn randomly_edit(
1548        &mut self,
1549        rng: &mut impl rand::Rng,
1550        edit_count: usize,
1551        cx: &mut ModelContext<Self>,
1552    ) {
1553        use util::RandomCharIter;
1554
1555        let snapshot = self.read(cx);
1556        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1557        let mut last_end = None;
1558        for _ in 0..edit_count {
1559            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
1560                break;
1561            }
1562
1563            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1564            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
1565            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
1566            last_end = Some(end);
1567
1568            let mut range = start..end;
1569            if rng.gen_bool(0.2) {
1570                mem::swap(&mut range.start, &mut range.end);
1571            }
1572
1573            let new_text_len = rng.gen_range(0..10);
1574            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1575
1576            edits.push((range, new_text.into()));
1577        }
1578        log::info!("mutating multi-buffer with {:?}", edits);
1579        drop(snapshot);
1580
1581        self.edit(edits, None, cx);
1582    }
1583
1584    pub fn randomly_edit_excerpts(
1585        &mut self,
1586        rng: &mut impl rand::Rng,
1587        mutation_count: usize,
1588        cx: &mut ModelContext<Self>,
1589    ) {
1590        use rand::prelude::*;
1591        use std::env;
1592        use util::RandomCharIter;
1593
1594        let max_excerpts = env::var("MAX_EXCERPTS")
1595            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1596            .unwrap_or(5);
1597
1598        let mut buffers = Vec::new();
1599        for _ in 0..mutation_count {
1600            if rng.gen_bool(0.05) {
1601                log::info!("Clearing multi-buffer");
1602                self.clear(cx);
1603                continue;
1604            }
1605
1606            let excerpt_ids = self.excerpt_ids();
1607            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1608                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1609                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1610                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
1611                    let buffer = buffers.last().unwrap().read(cx);
1612                    log::info!(
1613                        "Creating new buffer {} with text: {:?}",
1614                        buffer.remote_id(),
1615                        buffer.text()
1616                    );
1617                    buffers.last().unwrap().clone()
1618                } else {
1619                    self.buffers
1620                        .borrow()
1621                        .values()
1622                        .choose(rng)
1623                        .unwrap()
1624                        .buffer
1625                        .clone()
1626                };
1627
1628                let buffer = buffer_handle.read(cx);
1629                let buffer_text = buffer.text();
1630                let ranges = (0..rng.gen_range(0..5))
1631                    .map(|_| {
1632                        let end_ix =
1633                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1634                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1635                        ExcerptRange {
1636                            context: start_ix..end_ix,
1637                            primary: None,
1638                        }
1639                    })
1640                    .collect::<Vec<_>>();
1641                log::info!(
1642                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
1643                    buffer_handle.read(cx).remote_id(),
1644                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
1645                    ranges
1646                        .iter()
1647                        .map(|r| &buffer_text[r.context.clone()])
1648                        .collect::<Vec<_>>()
1649                );
1650
1651                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
1652                log::info!("Inserted with ids: {:?}", excerpt_id);
1653            } else {
1654                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1655                let mut excerpts_to_remove = excerpt_ids
1656                    .choose_multiple(rng, remove_count)
1657                    .cloned()
1658                    .collect::<Vec<_>>();
1659                let snapshot = self.snapshot.borrow();
1660                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &*snapshot));
1661                drop(snapshot);
1662                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1663                self.remove_excerpts(excerpts_to_remove, cx);
1664            }
1665        }
1666    }
1667
1668    pub fn randomly_mutate(
1669        &mut self,
1670        rng: &mut impl rand::Rng,
1671        mutation_count: usize,
1672        cx: &mut ModelContext<Self>,
1673    ) {
1674        use rand::prelude::*;
1675
1676        if rng.gen_bool(0.7) || self.singleton {
1677            let buffer = self
1678                .buffers
1679                .borrow()
1680                .values()
1681                .choose(rng)
1682                .map(|state| state.buffer.clone());
1683
1684            if let Some(buffer) = buffer {
1685                buffer.update(cx, |buffer, cx| {
1686                    if rng.gen() {
1687                        buffer.randomly_edit(rng, mutation_count, cx);
1688                    } else {
1689                        buffer.randomly_undo_redo(rng, cx);
1690                    }
1691                });
1692            } else {
1693                self.randomly_edit(rng, mutation_count, cx);
1694            }
1695        } else {
1696            self.randomly_edit_excerpts(rng, mutation_count, cx);
1697        }
1698
1699        self.check_invariants(cx);
1700    }
1701
1702    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
1703        let snapshot = self.read(cx);
1704        let excerpts = snapshot.excerpts.items(&());
1705        let excerpt_ids = snapshot.excerpt_ids.items(&());
1706
1707        for (ix, excerpt) in excerpts.iter().enumerate() {
1708            if ix == 0 {
1709                if excerpt.locator <= Locator::min() {
1710                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
1711                }
1712            } else {
1713                if excerpt.locator <= excerpts[ix - 1].locator {
1714                    panic!("excerpts are out-of-order: {:?}", excerpts);
1715                }
1716            }
1717        }
1718
1719        for (ix, entry) in excerpt_ids.iter().enumerate() {
1720            if ix == 0 {
1721                if entry.id.cmp(&ExcerptId::min(), &*snapshot).is_le() {
1722                    panic!("invalid first excerpt id {:?}", entry.id);
1723                }
1724            } else {
1725                if entry.id <= excerpt_ids[ix - 1].id {
1726                    panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
1727                }
1728            }
1729        }
1730    }
1731}
1732
1733impl Entity for MultiBuffer {
1734    type Event = Event;
1735}
1736
1737impl MultiBufferSnapshot {
1738    pub fn text(&self) -> String {
1739        self.chunks(0..self.len(), false)
1740            .map(|chunk| chunk.text)
1741            .collect()
1742    }
1743
1744    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1745        let mut offset = position.to_offset(self);
1746        let mut cursor = self.excerpts.cursor::<usize>();
1747        cursor.seek(&offset, Bias::Left, &());
1748        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1749            let end_before_footer = cursor.start() + excerpt.text_summary.len;
1750            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1751            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1752            excerpt.buffer.reversed_chunks_in_range(start..end)
1753        });
1754        iter::from_fn(move || {
1755            if offset == *cursor.start() {
1756                cursor.prev(&());
1757                let excerpt = cursor.item()?;
1758                excerpt_chunks = Some(
1759                    excerpt
1760                        .buffer
1761                        .reversed_chunks_in_range(excerpt.range.context.clone()),
1762                );
1763            }
1764
1765            let excerpt = cursor.item().unwrap();
1766            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1767                offset -= 1;
1768                Some("\n")
1769            } else {
1770                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1771                offset -= chunk.len();
1772                Some(chunk)
1773            }
1774        })
1775        .flat_map(|c| c.chars().rev())
1776    }
1777
1778    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1779        let offset = position.to_offset(self);
1780        self.text_for_range(offset..self.len())
1781            .flat_map(|chunk| chunk.chars())
1782    }
1783
1784    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
1785        self.chunks(range, false).map(|chunk| chunk.text)
1786    }
1787
1788    pub fn is_line_blank(&self, row: u32) -> bool {
1789        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1790            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1791    }
1792
1793    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1794    where
1795        T: ToOffset,
1796    {
1797        let position = position.to_offset(self);
1798        position == self.clip_offset(position, Bias::Left)
1799            && self
1800                .bytes_in_range(position..self.len())
1801                .flatten()
1802                .copied()
1803                .take(needle.len())
1804                .eq(needle.bytes())
1805    }
1806
1807    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
1808        let mut start = start.to_offset(self);
1809        let mut end = start;
1810        let mut next_chars = self.chars_at(start).peekable();
1811        let mut prev_chars = self.reversed_chars_at(start).peekable();
1812        let word_kind = cmp::max(
1813            prev_chars.peek().copied().map(char_kind),
1814            next_chars.peek().copied().map(char_kind),
1815        );
1816
1817        for ch in prev_chars {
1818            if Some(char_kind(ch)) == word_kind && ch != '\n' {
1819                start -= ch.len_utf8();
1820            } else {
1821                break;
1822            }
1823        }
1824
1825        for ch in next_chars {
1826            if Some(char_kind(ch)) == word_kind && ch != '\n' {
1827                end += ch.len_utf8();
1828            } else {
1829                break;
1830            }
1831        }
1832
1833        (start..end, word_kind)
1834    }
1835
1836    pub fn as_singleton(&self) -> Option<(&ExcerptId, u64, &BufferSnapshot)> {
1837        if self.singleton {
1838            self.excerpts
1839                .iter()
1840                .next()
1841                .map(|e| (&e.id, e.buffer_id, &e.buffer))
1842        } else {
1843            None
1844        }
1845    }
1846
1847    pub fn len(&self) -> usize {
1848        self.excerpts.summary().text.len
1849    }
1850
1851    pub fn is_empty(&self) -> bool {
1852        self.excerpts.summary().text.len == 0
1853    }
1854
1855    pub fn max_buffer_row(&self) -> u32 {
1856        self.excerpts.summary().max_buffer_row
1857    }
1858
1859    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1860        if let Some((_, _, buffer)) = self.as_singleton() {
1861            return buffer.clip_offset(offset, bias);
1862        }
1863
1864        let mut cursor = self.excerpts.cursor::<usize>();
1865        cursor.seek(&offset, Bias::Right, &());
1866        let overshoot = if let Some(excerpt) = cursor.item() {
1867            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1868            let buffer_offset = excerpt
1869                .buffer
1870                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1871            buffer_offset.saturating_sub(excerpt_start)
1872        } else {
1873            0
1874        };
1875        cursor.start() + overshoot
1876    }
1877
1878    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1879        if let Some((_, _, buffer)) = self.as_singleton() {
1880            return buffer.clip_point(point, bias);
1881        }
1882
1883        let mut cursor = self.excerpts.cursor::<Point>();
1884        cursor.seek(&point, Bias::Right, &());
1885        let overshoot = if let Some(excerpt) = cursor.item() {
1886            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
1887            let buffer_point = excerpt
1888                .buffer
1889                .clip_point(excerpt_start + (point - cursor.start()), bias);
1890            buffer_point.saturating_sub(excerpt_start)
1891        } else {
1892            Point::zero()
1893        };
1894        *cursor.start() + overshoot
1895    }
1896
1897    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
1898        if let Some((_, _, buffer)) = self.as_singleton() {
1899            return buffer.clip_offset_utf16(offset, bias);
1900        }
1901
1902        let mut cursor = self.excerpts.cursor::<OffsetUtf16>();
1903        cursor.seek(&offset, Bias::Right, &());
1904        let overshoot = if let Some(excerpt) = cursor.item() {
1905            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
1906            let buffer_offset = excerpt
1907                .buffer
1908                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
1909            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
1910        } else {
1911            OffsetUtf16(0)
1912        };
1913        *cursor.start() + overshoot
1914    }
1915
1916    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
1917        if let Some((_, _, buffer)) = self.as_singleton() {
1918            return buffer.clip_point_utf16(point, bias);
1919        }
1920
1921        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1922        cursor.seek(&point.0, Bias::Right, &());
1923        let overshoot = if let Some(excerpt) = cursor.item() {
1924            let excerpt_start = excerpt
1925                .buffer
1926                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
1927            let buffer_point = excerpt
1928                .buffer
1929                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
1930            buffer_point.saturating_sub(excerpt_start)
1931        } else {
1932            PointUtf16::zero()
1933        };
1934        *cursor.start() + overshoot
1935    }
1936
1937    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
1938        let range = range.start.to_offset(self)..range.end.to_offset(self);
1939        let mut excerpts = self.excerpts.cursor::<usize>();
1940        excerpts.seek(&range.start, Bias::Right, &());
1941
1942        let mut chunk = &[][..];
1943        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1944            let mut excerpt_bytes = excerpt
1945                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1946            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1947            Some(excerpt_bytes)
1948        } else {
1949            None
1950        };
1951
1952        MultiBufferBytes {
1953            range,
1954            excerpts,
1955            excerpt_bytes,
1956            chunk,
1957        }
1958    }
1959
1960    pub fn buffer_rows(&self, start_row: u32) -> MultiBufferRows {
1961        let mut result = MultiBufferRows {
1962            buffer_row_range: 0..0,
1963            excerpts: self.excerpts.cursor(),
1964        };
1965        result.seek(start_row);
1966        result
1967    }
1968
1969    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
1970        let range = range.start.to_offset(self)..range.end.to_offset(self);
1971        let mut chunks = MultiBufferChunks {
1972            range: range.clone(),
1973            excerpts: self.excerpts.cursor(),
1974            excerpt_chunks: None,
1975            language_aware,
1976        };
1977        chunks.seek(range.start);
1978        chunks
1979    }
1980
1981    pub fn offset_to_point(&self, offset: usize) -> Point {
1982        if let Some((_, _, buffer)) = self.as_singleton() {
1983            return buffer.offset_to_point(offset);
1984        }
1985
1986        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1987        cursor.seek(&offset, Bias::Right, &());
1988        if let Some(excerpt) = cursor.item() {
1989            let (start_offset, start_point) = cursor.start();
1990            let overshoot = offset - start_offset;
1991            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
1992            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
1993            let buffer_point = excerpt
1994                .buffer
1995                .offset_to_point(excerpt_start_offset + overshoot);
1996            *start_point + (buffer_point - excerpt_start_point)
1997        } else {
1998            self.excerpts.summary().text.lines
1999        }
2000    }
2001
2002    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2003        if let Some((_, _, buffer)) = self.as_singleton() {
2004            return buffer.offset_to_point_utf16(offset);
2005        }
2006
2007        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
2008        cursor.seek(&offset, Bias::Right, &());
2009        if let Some(excerpt) = cursor.item() {
2010            let (start_offset, start_point) = cursor.start();
2011            let overshoot = offset - start_offset;
2012            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2013            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2014            let buffer_point = excerpt
2015                .buffer
2016                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2017            *start_point + (buffer_point - excerpt_start_point)
2018        } else {
2019            self.excerpts.summary().text.lines_utf16()
2020        }
2021    }
2022
2023    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2024        if let Some((_, _, buffer)) = self.as_singleton() {
2025            return buffer.point_to_point_utf16(point);
2026        }
2027
2028        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
2029        cursor.seek(&point, Bias::Right, &());
2030        if let Some(excerpt) = cursor.item() {
2031            let (start_offset, start_point) = cursor.start();
2032            let overshoot = point - start_offset;
2033            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2034            let excerpt_start_point_utf16 =
2035                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2036            let buffer_point = excerpt
2037                .buffer
2038                .point_to_point_utf16(excerpt_start_point + overshoot);
2039            *start_point + (buffer_point - excerpt_start_point_utf16)
2040        } else {
2041            self.excerpts.summary().text.lines_utf16()
2042        }
2043    }
2044
2045    pub fn point_to_offset(&self, point: Point) -> usize {
2046        if let Some((_, _, buffer)) = self.as_singleton() {
2047            return buffer.point_to_offset(point);
2048        }
2049
2050        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
2051        cursor.seek(&point, Bias::Right, &());
2052        if let Some(excerpt) = cursor.item() {
2053            let (start_point, start_offset) = cursor.start();
2054            let overshoot = point - start_point;
2055            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2056            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2057            let buffer_offset = excerpt
2058                .buffer
2059                .point_to_offset(excerpt_start_point + overshoot);
2060            *start_offset + buffer_offset - excerpt_start_offset
2061        } else {
2062            self.excerpts.summary().text.len
2063        }
2064    }
2065
2066    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2067        if let Some((_, _, buffer)) = self.as_singleton() {
2068            return buffer.offset_utf16_to_offset(offset_utf16);
2069        }
2070
2071        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>();
2072        cursor.seek(&offset_utf16, Bias::Right, &());
2073        if let Some(excerpt) = cursor.item() {
2074            let (start_offset_utf16, start_offset) = cursor.start();
2075            let overshoot = offset_utf16 - start_offset_utf16;
2076            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2077            let excerpt_start_offset_utf16 =
2078                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2079            let buffer_offset = excerpt
2080                .buffer
2081                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2082            *start_offset + (buffer_offset - excerpt_start_offset)
2083        } else {
2084            self.excerpts.summary().text.len
2085        }
2086    }
2087
2088    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2089        if let Some((_, _, buffer)) = self.as_singleton() {
2090            return buffer.offset_to_offset_utf16(offset);
2091        }
2092
2093        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>();
2094        cursor.seek(&offset, Bias::Right, &());
2095        if let Some(excerpt) = cursor.item() {
2096            let (start_offset, start_offset_utf16) = cursor.start();
2097            let overshoot = offset - start_offset;
2098            let excerpt_start_offset_utf16 =
2099                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2100            let excerpt_start_offset = excerpt
2101                .buffer
2102                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2103            let buffer_offset_utf16 = excerpt
2104                .buffer
2105                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2106            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2107        } else {
2108            self.excerpts.summary().text.len_utf16
2109        }
2110    }
2111
2112    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2113        if let Some((_, _, buffer)) = self.as_singleton() {
2114            return buffer.point_utf16_to_offset(point);
2115        }
2116
2117        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
2118        cursor.seek(&point, Bias::Right, &());
2119        if let Some(excerpt) = cursor.item() {
2120            let (start_point, start_offset) = cursor.start();
2121            let overshoot = point - start_point;
2122            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2123            let excerpt_start_point = excerpt
2124                .buffer
2125                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2126            let buffer_offset = excerpt
2127                .buffer
2128                .point_utf16_to_offset(excerpt_start_point + overshoot);
2129            *start_offset + (buffer_offset - excerpt_start_offset)
2130        } else {
2131            self.excerpts.summary().text.len
2132        }
2133    }
2134
2135    pub fn point_to_buffer_offset<T: ToOffset>(
2136        &self,
2137        point: T,
2138    ) -> Option<(&BufferSnapshot, usize)> {
2139        let offset = point.to_offset(&self);
2140        let mut cursor = self.excerpts.cursor::<usize>();
2141        cursor.seek(&offset, Bias::Right, &());
2142        if cursor.item().is_none() {
2143            cursor.prev(&());
2144        }
2145
2146        cursor.item().map(|excerpt| {
2147            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2148            let buffer_point = excerpt_start + offset - *cursor.start();
2149            (&excerpt.buffer, buffer_point)
2150        })
2151    }
2152
2153    pub fn suggested_indents(
2154        &self,
2155        rows: impl IntoIterator<Item = u32>,
2156        cx: &AppContext,
2157    ) -> BTreeMap<u32, IndentSize> {
2158        let mut result = BTreeMap::new();
2159
2160        let mut rows_for_excerpt = Vec::new();
2161        let mut cursor = self.excerpts.cursor::<Point>();
2162        let mut rows = rows.into_iter().peekable();
2163        let mut prev_row = u32::MAX;
2164        let mut prev_language_indent_size = IndentSize::default();
2165
2166        while let Some(row) = rows.next() {
2167            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2168            let excerpt = match cursor.item() {
2169                Some(excerpt) => excerpt,
2170                _ => continue,
2171            };
2172
2173            // Retrieve the language and indent size once for each disjoint region being indented.
2174            let single_indent_size = if row.saturating_sub(1) == prev_row {
2175                prev_language_indent_size
2176            } else {
2177                excerpt
2178                    .buffer
2179                    .language_indent_size_at(Point::new(row, 0), cx)
2180            };
2181            prev_language_indent_size = single_indent_size;
2182            prev_row = row;
2183
2184            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2185            let start_multibuffer_row = cursor.start().row;
2186
2187            rows_for_excerpt.push(row);
2188            while let Some(next_row) = rows.peek().copied() {
2189                if cursor.end(&()).row > next_row {
2190                    rows_for_excerpt.push(next_row);
2191                    rows.next();
2192                } else {
2193                    break;
2194                }
2195            }
2196
2197            let buffer_rows = rows_for_excerpt
2198                .drain(..)
2199                .map(|row| start_buffer_row + row - start_multibuffer_row);
2200            let buffer_indents = excerpt
2201                .buffer
2202                .suggested_indents(buffer_rows, single_indent_size);
2203            let multibuffer_indents = buffer_indents
2204                .into_iter()
2205                .map(|(row, indent)| (start_multibuffer_row + row - start_buffer_row, indent));
2206            result.extend(multibuffer_indents);
2207        }
2208
2209        result
2210    }
2211
2212    pub fn indent_size_for_line(&self, row: u32) -> IndentSize {
2213        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2214            let mut size = buffer.indent_size_for_line(range.start.row);
2215            size.len = size
2216                .len
2217                .min(range.end.column)
2218                .saturating_sub(range.start.column);
2219            size
2220        } else {
2221            IndentSize::spaces(0)
2222        }
2223    }
2224
2225    pub fn line_len(&self, row: u32) -> u32 {
2226        if let Some((_, range)) = self.buffer_line_for_row(row) {
2227            range.end.column - range.start.column
2228        } else {
2229            0
2230        }
2231    }
2232
2233    pub fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
2234        let mut cursor = self.excerpts.cursor::<Point>();
2235        let point = Point::new(row, 0);
2236        cursor.seek(&point, Bias::Right, &());
2237        if cursor.item().is_none() && *cursor.start() == point {
2238            cursor.prev(&());
2239        }
2240        if let Some(excerpt) = cursor.item() {
2241            let overshoot = row - cursor.start().row;
2242            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2243            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2244            let buffer_row = excerpt_start.row + overshoot;
2245            let line_start = Point::new(buffer_row, 0);
2246            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2247            return Some((
2248                &excerpt.buffer,
2249                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2250            ));
2251        }
2252        None
2253    }
2254
2255    pub fn max_point(&self) -> Point {
2256        self.text_summary().lines
2257    }
2258
2259    pub fn text_summary(&self) -> TextSummary {
2260        self.excerpts.summary().text.clone()
2261    }
2262
2263    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2264    where
2265        D: TextDimension,
2266        O: ToOffset,
2267    {
2268        let mut summary = D::default();
2269        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2270        let mut cursor = self.excerpts.cursor::<usize>();
2271        cursor.seek(&range.start, Bias::Right, &());
2272        if let Some(excerpt) = cursor.item() {
2273            let mut end_before_newline = cursor.end(&());
2274            if excerpt.has_trailing_newline {
2275                end_before_newline -= 1;
2276            }
2277
2278            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2279            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2280            let end_in_excerpt =
2281                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2282            summary.add_assign(
2283                &excerpt
2284                    .buffer
2285                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2286            );
2287
2288            if range.end > end_before_newline {
2289                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2290            }
2291
2292            cursor.next(&());
2293        }
2294
2295        if range.end > *cursor.start() {
2296            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2297                &range.end,
2298                Bias::Right,
2299                &(),
2300            )));
2301            if let Some(excerpt) = cursor.item() {
2302                range.end = cmp::max(*cursor.start(), range.end);
2303
2304                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2305                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2306                summary.add_assign(
2307                    &excerpt
2308                        .buffer
2309                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2310                );
2311            }
2312        }
2313
2314        summary
2315    }
2316
2317    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2318    where
2319        D: TextDimension + Ord + Sub<D, Output = D>,
2320    {
2321        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2322        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
2323
2324        cursor.seek(locator, Bias::Left, &());
2325        if cursor.item().is_none() {
2326            cursor.next(&());
2327        }
2328
2329        let mut position = D::from_text_summary(&cursor.start().text);
2330        if let Some(excerpt) = cursor.item() {
2331            if excerpt.id == anchor.excerpt_id {
2332                let excerpt_buffer_start =
2333                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2334                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2335                let buffer_position = cmp::min(
2336                    excerpt_buffer_end,
2337                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
2338                );
2339                if buffer_position > excerpt_buffer_start {
2340                    position.add_assign(&(buffer_position - excerpt_buffer_start));
2341                }
2342            }
2343        }
2344        position
2345    }
2346
2347    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
2348    where
2349        D: TextDimension + Ord + Sub<D, Output = D>,
2350        I: 'a + IntoIterator<Item = &'a Anchor>,
2351    {
2352        if let Some((_, _, buffer)) = self.as_singleton() {
2353            return buffer
2354                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
2355                .collect();
2356        }
2357
2358        let mut anchors = anchors.into_iter().peekable();
2359        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2360        let mut summaries = Vec::new();
2361        while let Some(anchor) = anchors.peek() {
2362            let excerpt_id = anchor.excerpt_id;
2363            let excerpt_anchors = iter::from_fn(|| {
2364                let anchor = anchors.peek()?;
2365                if anchor.excerpt_id == excerpt_id {
2366                    Some(&anchors.next().unwrap().text_anchor)
2367                } else {
2368                    None
2369                }
2370            });
2371
2372            let locator = self.excerpt_locator_for_id(excerpt_id);
2373            cursor.seek_forward(locator, Bias::Left, &());
2374            if cursor.item().is_none() {
2375                cursor.next(&());
2376            }
2377
2378            let position = D::from_text_summary(&cursor.start().text);
2379            if let Some(excerpt) = cursor.item() {
2380                if excerpt.id == excerpt_id {
2381                    let excerpt_buffer_start =
2382                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2383                    let excerpt_buffer_end =
2384                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2385                    summaries.extend(
2386                        excerpt
2387                            .buffer
2388                            .summaries_for_anchors::<D, _>(excerpt_anchors)
2389                            .map(move |summary| {
2390                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
2391                                let mut position = position.clone();
2392                                let excerpt_buffer_start = excerpt_buffer_start.clone();
2393                                if summary > excerpt_buffer_start {
2394                                    position.add_assign(&(summary - excerpt_buffer_start));
2395                                }
2396                                position
2397                            }),
2398                    );
2399                    continue;
2400                }
2401            }
2402
2403            summaries.extend(excerpt_anchors.map(|_| position.clone()));
2404        }
2405
2406        summaries
2407    }
2408
2409    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
2410    where
2411        I: 'a + IntoIterator<Item = &'a Anchor>,
2412    {
2413        let mut anchors = anchors.into_iter().enumerate().peekable();
2414        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2415        cursor.next(&());
2416
2417        let mut result = Vec::new();
2418
2419        while let Some((_, anchor)) = anchors.peek() {
2420            let old_excerpt_id = anchor.excerpt_id;
2421
2422            // Find the location where this anchor's excerpt should be.
2423            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
2424            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
2425
2426            if cursor.item().is_none() {
2427                cursor.next(&());
2428            }
2429
2430            let next_excerpt = cursor.item();
2431            let prev_excerpt = cursor.prev_item();
2432
2433            // Process all of the anchors for this excerpt.
2434            while let Some((_, anchor)) = anchors.peek() {
2435                if anchor.excerpt_id != old_excerpt_id {
2436                    break;
2437                }
2438                let (anchor_ix, anchor) = anchors.next().unwrap();
2439                let mut anchor = *anchor;
2440
2441                // Leave min and max anchors unchanged if invalid or
2442                // if the old excerpt still exists at this location
2443                let mut kept_position = next_excerpt
2444                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
2445                    || old_excerpt_id == ExcerptId::max()
2446                    || old_excerpt_id == ExcerptId::min();
2447
2448                // If the old excerpt no longer exists at this location, then attempt to
2449                // find an equivalent position for this anchor in an adjacent excerpt.
2450                if !kept_position {
2451                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
2452                        if excerpt.contains(&anchor) {
2453                            anchor.excerpt_id = excerpt.id.clone();
2454                            kept_position = true;
2455                            break;
2456                        }
2457                    }
2458                }
2459
2460                // If there's no adjacent excerpt that contains the anchor's position,
2461                // then report that the anchor has lost its position.
2462                if !kept_position {
2463                    anchor = if let Some(excerpt) = next_excerpt {
2464                        let mut text_anchor = excerpt
2465                            .range
2466                            .context
2467                            .start
2468                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2469                        if text_anchor
2470                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
2471                            .is_gt()
2472                        {
2473                            text_anchor = excerpt.range.context.end;
2474                        }
2475                        Anchor {
2476                            buffer_id: Some(excerpt.buffer_id),
2477                            excerpt_id: excerpt.id.clone(),
2478                            text_anchor,
2479                        }
2480                    } else if let Some(excerpt) = prev_excerpt {
2481                        let mut text_anchor = excerpt
2482                            .range
2483                            .context
2484                            .end
2485                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2486                        if text_anchor
2487                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
2488                            .is_lt()
2489                        {
2490                            text_anchor = excerpt.range.context.start;
2491                        }
2492                        Anchor {
2493                            buffer_id: Some(excerpt.buffer_id),
2494                            excerpt_id: excerpt.id.clone(),
2495                            text_anchor,
2496                        }
2497                    } else if anchor.text_anchor.bias == Bias::Left {
2498                        Anchor::min()
2499                    } else {
2500                        Anchor::max()
2501                    };
2502                }
2503
2504                result.push((anchor_ix, anchor, kept_position));
2505            }
2506        }
2507        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
2508        result
2509    }
2510
2511    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2512        self.anchor_at(position, Bias::Left)
2513    }
2514
2515    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2516        self.anchor_at(position, Bias::Right)
2517    }
2518
2519    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
2520        let offset = position.to_offset(self);
2521        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
2522            return Anchor {
2523                buffer_id: Some(buffer_id),
2524                excerpt_id: excerpt_id.clone(),
2525                text_anchor: buffer.anchor_at(offset, bias),
2526            };
2527        }
2528
2529        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>();
2530        cursor.seek(&offset, Bias::Right, &());
2531        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
2532            cursor.prev(&());
2533        }
2534        if let Some(excerpt) = cursor.item() {
2535            let mut overshoot = offset.saturating_sub(cursor.start().0);
2536            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
2537                overshoot -= 1;
2538                bias = Bias::Right;
2539            }
2540
2541            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2542            let text_anchor =
2543                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
2544            Anchor {
2545                buffer_id: Some(excerpt.buffer_id),
2546                excerpt_id: excerpt.id.clone(),
2547                text_anchor,
2548            }
2549        } else if offset == 0 && bias == Bias::Left {
2550            Anchor::min()
2551        } else {
2552            Anchor::max()
2553        }
2554    }
2555
2556    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
2557        let locator = self.excerpt_locator_for_id(excerpt_id);
2558        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2559        cursor.seek(locator, Bias::Left, &());
2560        if let Some(excerpt) = cursor.item() {
2561            if excerpt.id == excerpt_id {
2562                let text_anchor = excerpt.clip_anchor(text_anchor);
2563                drop(cursor);
2564                return Anchor {
2565                    buffer_id: Some(excerpt.buffer_id),
2566                    excerpt_id,
2567                    text_anchor,
2568                };
2569            }
2570        }
2571        panic!("excerpt not found");
2572    }
2573
2574    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2575        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
2576            true
2577        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
2578            excerpt.buffer.can_resolve(&anchor.text_anchor)
2579        } else {
2580            false
2581        }
2582    }
2583
2584    pub fn excerpts(
2585        &self,
2586    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
2587        self.excerpts
2588            .iter()
2589            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
2590    }
2591
2592    pub fn excerpt_boundaries_in_range<R, T>(
2593        &self,
2594        range: R,
2595    ) -> impl Iterator<Item = ExcerptBoundary> + '_
2596    where
2597        R: RangeBounds<T>,
2598        T: ToOffset,
2599    {
2600        let start_offset;
2601        let start = match range.start_bound() {
2602            Bound::Included(start) => {
2603                start_offset = start.to_offset(self);
2604                Bound::Included(start_offset)
2605            }
2606            Bound::Excluded(start) => {
2607                start_offset = start.to_offset(self);
2608                Bound::Excluded(start_offset)
2609            }
2610            Bound::Unbounded => {
2611                start_offset = 0;
2612                Bound::Unbounded
2613            }
2614        };
2615        let end = match range.end_bound() {
2616            Bound::Included(end) => Bound::Included(end.to_offset(self)),
2617            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
2618            Bound::Unbounded => Bound::Unbounded,
2619        };
2620        let bounds = (start, end);
2621
2622        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2623        cursor.seek(&start_offset, Bias::Right, &());
2624        if cursor.item().is_none() {
2625            cursor.prev(&());
2626        }
2627        if !bounds.contains(&cursor.start().0) {
2628            cursor.next(&());
2629        }
2630
2631        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
2632        std::iter::from_fn(move || {
2633            if self.singleton {
2634                None
2635            } else if bounds.contains(&cursor.start().0) {
2636                let excerpt = cursor.item()?;
2637                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
2638                let boundary = ExcerptBoundary {
2639                    id: excerpt.id.clone(),
2640                    row: cursor.start().1.row,
2641                    buffer: excerpt.buffer.clone(),
2642                    range: excerpt.range.clone(),
2643                    starts_new_buffer,
2644                };
2645
2646                prev_buffer_id = Some(excerpt.buffer_id);
2647                cursor.next(&());
2648                Some(boundary)
2649            } else {
2650                None
2651            }
2652        })
2653    }
2654
2655    pub fn edit_count(&self) -> usize {
2656        self.edit_count
2657    }
2658
2659    pub fn parse_count(&self) -> usize {
2660        self.parse_count
2661    }
2662
2663    /// Returns the smallest enclosing bracket ranges containing the given range or
2664    /// None if no brackets contain range or the range is not contained in a single
2665    /// excerpt
2666    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
2667        &self,
2668        range: Range<T>,
2669    ) -> Option<(Range<usize>, Range<usize>)> {
2670        let range = range.start.to_offset(self)..range.end.to_offset(self);
2671
2672        // Get the ranges of the innermost pair of brackets.
2673        let mut result: Option<(Range<usize>, Range<usize>)> = None;
2674
2675        let Some(enclosing_bracket_ranges) = self.enclosing_bracket_ranges(range.clone()) else { return None; };
2676
2677        for (open, close) in enclosing_bracket_ranges {
2678            let len = close.end - open.start;
2679
2680            if let Some((existing_open, existing_close)) = &result {
2681                let existing_len = existing_close.end - existing_open.start;
2682                if len > existing_len {
2683                    continue;
2684                }
2685            }
2686
2687            result = Some((open, close));
2688        }
2689
2690        result
2691    }
2692
2693    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
2694    /// not contained in a single excerpt
2695    pub fn enclosing_bracket_ranges<'a, T: ToOffset>(
2696        &'a self,
2697        range: Range<T>,
2698    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + 'a> {
2699        let range = range.start.to_offset(self)..range.end.to_offset(self);
2700
2701        self.bracket_ranges(range.clone()).map(|range_pairs| {
2702            range_pairs
2703                .filter(move |(open, close)| open.start <= range.start && close.end >= range.end)
2704        })
2705    }
2706
2707    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
2708    /// not contained in a single excerpt
2709    pub fn bracket_ranges<'a, T: ToOffset>(
2710        &'a self,
2711        range: Range<T>,
2712    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + 'a> {
2713        let range = range.start.to_offset(self)..range.end.to_offset(self);
2714        let excerpt = self.excerpt_containing(range.clone());
2715        excerpt.map(|(excerpt, excerpt_offset)| {
2716            let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2717            let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
2718
2719            let start_in_buffer = excerpt_buffer_start + range.start.saturating_sub(excerpt_offset);
2720            let end_in_buffer = excerpt_buffer_start + range.end.saturating_sub(excerpt_offset);
2721
2722            excerpt
2723                .buffer
2724                .bracket_ranges(start_in_buffer..end_in_buffer)
2725                .filter_map(move |(start_bracket_range, end_bracket_range)| {
2726                    if start_bracket_range.start < excerpt_buffer_start
2727                        || end_bracket_range.end > excerpt_buffer_end
2728                    {
2729                        return None;
2730                    }
2731
2732                    let mut start_bracket_range = start_bracket_range.clone();
2733                    start_bracket_range.start =
2734                        excerpt_offset + (start_bracket_range.start - excerpt_buffer_start);
2735                    start_bracket_range.end =
2736                        excerpt_offset + (start_bracket_range.end - excerpt_buffer_start);
2737
2738                    let mut end_bracket_range = end_bracket_range.clone();
2739                    end_bracket_range.start =
2740                        excerpt_offset + (end_bracket_range.start - excerpt_buffer_start);
2741                    end_bracket_range.end =
2742                        excerpt_offset + (end_bracket_range.end - excerpt_buffer_start);
2743                    Some((start_bracket_range, end_bracket_range))
2744                })
2745        })
2746    }
2747
2748    pub fn diagnostics_update_count(&self) -> usize {
2749        self.diagnostics_update_count
2750    }
2751
2752    pub fn git_diff_update_count(&self) -> usize {
2753        self.git_diff_update_count
2754    }
2755
2756    pub fn trailing_excerpt_update_count(&self) -> usize {
2757        self.trailing_excerpt_update_count
2758    }
2759
2760    pub fn file_at<'a, T: ToOffset>(&'a self, point: T) -> Option<&'a Arc<dyn File>> {
2761        self.point_to_buffer_offset(point)
2762            .and_then(|(buffer, _)| buffer.file())
2763    }
2764
2765    pub fn language_at<'a, T: ToOffset>(&'a self, point: T) -> Option<&'a Arc<Language>> {
2766        self.point_to_buffer_offset(point)
2767            .and_then(|(buffer, offset)| buffer.language_at(offset))
2768    }
2769
2770    pub fn language_scope_at<'a, T: ToOffset>(&'a self, point: T) -> Option<LanguageScope> {
2771        self.point_to_buffer_offset(point)
2772            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
2773    }
2774
2775    pub fn language_indent_size_at<T: ToOffset>(
2776        &self,
2777        position: T,
2778        cx: &AppContext,
2779    ) -> Option<IndentSize> {
2780        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
2781        Some(buffer_snapshot.language_indent_size_at(offset, cx))
2782    }
2783
2784    pub fn is_dirty(&self) -> bool {
2785        self.is_dirty
2786    }
2787
2788    pub fn has_conflict(&self) -> bool {
2789        self.has_conflict
2790    }
2791
2792    pub fn diagnostic_group<'a, O>(
2793        &'a self,
2794        group_id: usize,
2795    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2796    where
2797        O: text::FromAnchor + 'a,
2798    {
2799        self.as_singleton()
2800            .into_iter()
2801            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
2802    }
2803
2804    pub fn diagnostics_in_range<'a, T, O>(
2805        &'a self,
2806        range: Range<T>,
2807        reversed: bool,
2808    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2809    where
2810        T: 'a + ToOffset,
2811        O: 'a + text::FromAnchor + Ord,
2812    {
2813        self.as_singleton()
2814            .into_iter()
2815            .flat_map(move |(_, _, buffer)| {
2816                buffer.diagnostics_in_range(
2817                    range.start.to_offset(self)..range.end.to_offset(self),
2818                    reversed,
2819                )
2820            })
2821    }
2822
2823    pub fn git_diff_hunks_in_range<'a>(
2824        &'a self,
2825        row_range: Range<u32>,
2826        reversed: bool,
2827    ) -> impl 'a + Iterator<Item = DiffHunk<u32>> {
2828        let mut cursor = self.excerpts.cursor::<Point>();
2829
2830        if reversed {
2831            cursor.seek(&Point::new(row_range.end, 0), Bias::Left, &());
2832            if cursor.item().is_none() {
2833                cursor.prev(&());
2834            }
2835        } else {
2836            cursor.seek(&Point::new(row_range.start, 0), Bias::Right, &());
2837        }
2838
2839        std::iter::from_fn(move || {
2840            let excerpt = cursor.item()?;
2841            let multibuffer_start = *cursor.start();
2842            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
2843            if multibuffer_start.row >= row_range.end {
2844                return None;
2845            }
2846
2847            let mut buffer_start = excerpt.range.context.start;
2848            let mut buffer_end = excerpt.range.context.end;
2849            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
2850            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
2851
2852            if row_range.start > multibuffer_start.row {
2853                let buffer_start_point =
2854                    excerpt_start_point + Point::new(row_range.start - multibuffer_start.row, 0);
2855                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
2856            }
2857
2858            if row_range.end < multibuffer_end.row {
2859                let buffer_end_point =
2860                    excerpt_start_point + Point::new(row_range.end - multibuffer_start.row, 0);
2861                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
2862            }
2863
2864            let buffer_hunks = excerpt
2865                .buffer
2866                .git_diff_hunks_intersecting_range(buffer_start..buffer_end, reversed)
2867                .filter_map(move |hunk| {
2868                    let start = multibuffer_start.row
2869                        + hunk
2870                            .buffer_range
2871                            .start
2872                            .saturating_sub(excerpt_start_point.row);
2873                    let end = multibuffer_start.row
2874                        + hunk
2875                            .buffer_range
2876                            .end
2877                            .min(excerpt_end_point.row + 1)
2878                            .saturating_sub(excerpt_start_point.row);
2879
2880                    Some(DiffHunk {
2881                        buffer_range: start..end,
2882                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
2883                    })
2884                });
2885
2886            if reversed {
2887                cursor.prev(&());
2888            } else {
2889                cursor.next(&());
2890            }
2891
2892            Some(buffer_hunks)
2893        })
2894        .flatten()
2895    }
2896
2897    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2898        let range = range.start.to_offset(self)..range.end.to_offset(self);
2899
2900        self.excerpt_containing(range.clone())
2901            .and_then(|(excerpt, excerpt_offset)| {
2902                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2903                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
2904
2905                let start_in_buffer =
2906                    excerpt_buffer_start + range.start.saturating_sub(excerpt_offset);
2907                let end_in_buffer = excerpt_buffer_start + range.end.saturating_sub(excerpt_offset);
2908                let mut ancestor_buffer_range = excerpt
2909                    .buffer
2910                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2911                ancestor_buffer_range.start =
2912                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2913                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2914
2915                let start = excerpt_offset + (ancestor_buffer_range.start - excerpt_buffer_start);
2916                let end = excerpt_offset + (ancestor_buffer_range.end - excerpt_buffer_start);
2917                Some(start..end)
2918            })
2919    }
2920
2921    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2922        let (excerpt_id, _, buffer) = self.as_singleton()?;
2923        let outline = buffer.outline(theme)?;
2924        Some(Outline::new(
2925            outline
2926                .items
2927                .into_iter()
2928                .map(|item| OutlineItem {
2929                    depth: item.depth,
2930                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
2931                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
2932                    text: item.text,
2933                    highlight_ranges: item.highlight_ranges,
2934                    name_ranges: item.name_ranges,
2935                })
2936                .collect(),
2937        ))
2938    }
2939
2940    pub fn symbols_containing<T: ToOffset>(
2941        &self,
2942        offset: T,
2943        theme: Option<&SyntaxTheme>,
2944    ) -> Option<(u64, Vec<OutlineItem<Anchor>>)> {
2945        let anchor = self.anchor_before(offset);
2946        let excerpt_id = anchor.excerpt_id();
2947        let excerpt = self.excerpt(excerpt_id)?;
2948        Some((
2949            excerpt.buffer_id,
2950            excerpt
2951                .buffer
2952                .symbols_containing(anchor.text_anchor, theme)
2953                .into_iter()
2954                .flatten()
2955                .map(|item| OutlineItem {
2956                    depth: item.depth,
2957                    range: self.anchor_in_excerpt(excerpt_id, item.range.start)
2958                        ..self.anchor_in_excerpt(excerpt_id, item.range.end),
2959                    text: item.text,
2960                    highlight_ranges: item.highlight_ranges,
2961                    name_ranges: item.name_ranges,
2962                })
2963                .collect(),
2964        ))
2965    }
2966
2967    fn excerpt_locator_for_id<'a>(&'a self, id: ExcerptId) -> &'a Locator {
2968        if id == ExcerptId::min() {
2969            Locator::min_ref()
2970        } else if id == ExcerptId::max() {
2971            Locator::max_ref()
2972        } else {
2973            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
2974            cursor.seek(&id, Bias::Left, &());
2975            if let Some(entry) = cursor.item() {
2976                if entry.id == id {
2977                    return &entry.locator;
2978                }
2979            }
2980            panic!("invalid excerpt id {:?}", id)
2981        }
2982    }
2983
2984    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<u64> {
2985        Some(self.excerpt(excerpt_id)?.buffer_id)
2986    }
2987
2988    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
2989        Some(&self.excerpt(excerpt_id)?.buffer)
2990    }
2991
2992    fn excerpt<'a>(&'a self, excerpt_id: ExcerptId) -> Option<&'a Excerpt> {
2993        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2994        let locator = self.excerpt_locator_for_id(excerpt_id);
2995        cursor.seek(&Some(locator), Bias::Left, &());
2996        if let Some(excerpt) = cursor.item() {
2997            if excerpt.id == excerpt_id {
2998                return Some(excerpt);
2999            }
3000        }
3001        None
3002    }
3003
3004    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
3005    fn excerpt_containing<'a, T: ToOffset>(
3006        &'a self,
3007        range: Range<T>,
3008    ) -> Option<(&'a Excerpt, usize)> {
3009        let range = range.start.to_offset(self)..range.end.to_offset(self);
3010
3011        let mut cursor = self.excerpts.cursor::<usize>();
3012        cursor.seek(&range.start, Bias::Right, &());
3013        let start_excerpt = cursor.item();
3014
3015        if range.start == range.end {
3016            return start_excerpt.map(|excerpt| (excerpt, *cursor.start()));
3017        }
3018
3019        cursor.seek(&range.end, Bias::Right, &());
3020        let end_excerpt = cursor.item();
3021
3022        start_excerpt
3023            .zip(end_excerpt)
3024            .and_then(|(start_excerpt, end_excerpt)| {
3025                if start_excerpt.id != end_excerpt.id {
3026                    return None;
3027                }
3028
3029                Some((start_excerpt, *cursor.start()))
3030            })
3031    }
3032
3033    pub fn remote_selections_in_range<'a>(
3034        &'a self,
3035        range: &'a Range<Anchor>,
3036    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
3037        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
3038        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
3039        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
3040        cursor.seek(start_locator, Bias::Left, &());
3041        cursor
3042            .take_while(move |excerpt| excerpt.locator <= *end_locator)
3043            .flat_map(move |excerpt| {
3044                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
3045                if excerpt.id == range.start.excerpt_id {
3046                    query_range.start = range.start.text_anchor;
3047                }
3048                if excerpt.id == range.end.excerpt_id {
3049                    query_range.end = range.end.text_anchor;
3050                }
3051
3052                excerpt
3053                    .buffer
3054                    .remote_selections_in_range(query_range)
3055                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
3056                        selections.map(move |selection| {
3057                            let mut start = Anchor {
3058                                buffer_id: Some(excerpt.buffer_id),
3059                                excerpt_id: excerpt.id.clone(),
3060                                text_anchor: selection.start,
3061                            };
3062                            let mut end = Anchor {
3063                                buffer_id: Some(excerpt.buffer_id),
3064                                excerpt_id: excerpt.id.clone(),
3065                                text_anchor: selection.end,
3066                            };
3067                            if range.start.cmp(&start, self).is_gt() {
3068                                start = range.start.clone();
3069                            }
3070                            if range.end.cmp(&end, self).is_lt() {
3071                                end = range.end.clone();
3072                            }
3073
3074                            (
3075                                replica_id,
3076                                line_mode,
3077                                cursor_shape,
3078                                Selection {
3079                                    id: selection.id,
3080                                    start,
3081                                    end,
3082                                    reversed: selection.reversed,
3083                                    goal: selection.goal,
3084                                },
3085                            )
3086                        })
3087                    })
3088            })
3089    }
3090}
3091
3092#[cfg(any(test, feature = "test-support"))]
3093impl MultiBufferSnapshot {
3094    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
3095        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
3096        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
3097        start..end
3098    }
3099}
3100
3101impl History {
3102    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
3103        self.transaction_depth += 1;
3104        if self.transaction_depth == 1 {
3105            let id = self.next_transaction_id.tick();
3106            self.undo_stack.push(Transaction {
3107                id,
3108                buffer_transactions: Default::default(),
3109                first_edit_at: now,
3110                last_edit_at: now,
3111                suppress_grouping: false,
3112            });
3113            Some(id)
3114        } else {
3115            None
3116        }
3117    }
3118
3119    fn end_transaction(
3120        &mut self,
3121        now: Instant,
3122        buffer_transactions: HashMap<u64, TransactionId>,
3123    ) -> bool {
3124        assert_ne!(self.transaction_depth, 0);
3125        self.transaction_depth -= 1;
3126        if self.transaction_depth == 0 {
3127            if buffer_transactions.is_empty() {
3128                self.undo_stack.pop();
3129                false
3130            } else {
3131                self.redo_stack.clear();
3132                let transaction = self.undo_stack.last_mut().unwrap();
3133                transaction.last_edit_at = now;
3134                for (buffer_id, transaction_id) in buffer_transactions {
3135                    transaction
3136                        .buffer_transactions
3137                        .entry(buffer_id)
3138                        .or_insert(transaction_id);
3139                }
3140                true
3141            }
3142        } else {
3143            false
3144        }
3145    }
3146
3147    fn push_transaction<'a, T>(
3148        &mut self,
3149        buffer_transactions: T,
3150        now: Instant,
3151        cx: &mut ModelContext<MultiBuffer>,
3152    ) where
3153        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
3154    {
3155        assert_eq!(self.transaction_depth, 0);
3156        let transaction = Transaction {
3157            id: self.next_transaction_id.tick(),
3158            buffer_transactions: buffer_transactions
3159                .into_iter()
3160                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
3161                .collect(),
3162            first_edit_at: now,
3163            last_edit_at: now,
3164            suppress_grouping: false,
3165        };
3166        if !transaction.buffer_transactions.is_empty() {
3167            self.undo_stack.push(transaction);
3168            self.redo_stack.clear();
3169        }
3170    }
3171
3172    fn finalize_last_transaction(&mut self) {
3173        if let Some(transaction) = self.undo_stack.last_mut() {
3174            transaction.suppress_grouping = true;
3175        }
3176    }
3177
3178    fn pop_undo(&mut self) -> Option<&mut Transaction> {
3179        assert_eq!(self.transaction_depth, 0);
3180        if let Some(transaction) = self.undo_stack.pop() {
3181            self.redo_stack.push(transaction);
3182            self.redo_stack.last_mut()
3183        } else {
3184            None
3185        }
3186    }
3187
3188    fn pop_redo(&mut self) -> Option<&mut Transaction> {
3189        assert_eq!(self.transaction_depth, 0);
3190        if let Some(transaction) = self.redo_stack.pop() {
3191            self.undo_stack.push(transaction);
3192            self.undo_stack.last_mut()
3193        } else {
3194            None
3195        }
3196    }
3197
3198    fn group(&mut self) -> Option<TransactionId> {
3199        let mut count = 0;
3200        let mut transactions = self.undo_stack.iter();
3201        if let Some(mut transaction) = transactions.next_back() {
3202            while let Some(prev_transaction) = transactions.next_back() {
3203                if !prev_transaction.suppress_grouping
3204                    && transaction.first_edit_at - prev_transaction.last_edit_at
3205                        <= self.group_interval
3206                {
3207                    transaction = prev_transaction;
3208                    count += 1;
3209                } else {
3210                    break;
3211                }
3212            }
3213        }
3214        self.group_trailing(count)
3215    }
3216
3217    fn group_until(&mut self, transaction_id: TransactionId) {
3218        let mut count = 0;
3219        for transaction in self.undo_stack.iter().rev() {
3220            if transaction.id == transaction_id {
3221                self.group_trailing(count);
3222                break;
3223            } else if transaction.suppress_grouping {
3224                break;
3225            } else {
3226                count += 1;
3227            }
3228        }
3229    }
3230
3231    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
3232        let new_len = self.undo_stack.len() - n;
3233        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
3234        if let Some(last_transaction) = transactions_to_keep.last_mut() {
3235            if let Some(transaction) = transactions_to_merge.last() {
3236                last_transaction.last_edit_at = transaction.last_edit_at;
3237            }
3238            for to_merge in transactions_to_merge {
3239                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
3240                    last_transaction
3241                        .buffer_transactions
3242                        .entry(*buffer_id)
3243                        .or_insert(*transaction_id);
3244                }
3245            }
3246        }
3247
3248        self.undo_stack.truncate(new_len);
3249        self.undo_stack.last().map(|t| t.id)
3250    }
3251}
3252
3253impl Excerpt {
3254    fn new(
3255        id: ExcerptId,
3256        locator: Locator,
3257        buffer_id: u64,
3258        buffer: BufferSnapshot,
3259        range: ExcerptRange<text::Anchor>,
3260        has_trailing_newline: bool,
3261    ) -> Self {
3262        Excerpt {
3263            id,
3264            locator,
3265            max_buffer_row: range.context.end.to_point(&buffer).row,
3266            text_summary: buffer
3267                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
3268            buffer_id,
3269            buffer,
3270            range,
3271            has_trailing_newline,
3272        }
3273    }
3274
3275    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
3276        let content_start = self.range.context.start.to_offset(&self.buffer);
3277        let chunks_start = content_start + range.start;
3278        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
3279
3280        let footer_height = if self.has_trailing_newline
3281            && range.start <= self.text_summary.len
3282            && range.end > self.text_summary.len
3283        {
3284            1
3285        } else {
3286            0
3287        };
3288
3289        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
3290
3291        ExcerptChunks {
3292            content_chunks,
3293            footer_height,
3294        }
3295    }
3296
3297    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3298        let content_start = self.range.context.start.to_offset(&self.buffer);
3299        let bytes_start = content_start + range.start;
3300        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3301        let footer_height = if self.has_trailing_newline
3302            && range.start <= self.text_summary.len
3303            && range.end > self.text_summary.len
3304        {
3305            1
3306        } else {
3307            0
3308        };
3309        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
3310
3311        ExcerptBytes {
3312            content_bytes,
3313            footer_height,
3314        }
3315    }
3316
3317    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
3318        if text_anchor
3319            .cmp(&self.range.context.start, &self.buffer)
3320            .is_lt()
3321        {
3322            self.range.context.start
3323        } else if text_anchor
3324            .cmp(&self.range.context.end, &self.buffer)
3325            .is_gt()
3326        {
3327            self.range.context.end
3328        } else {
3329            text_anchor
3330        }
3331    }
3332
3333    fn contains(&self, anchor: &Anchor) -> bool {
3334        Some(self.buffer_id) == anchor.buffer_id
3335            && self
3336                .range
3337                .context
3338                .start
3339                .cmp(&anchor.text_anchor, &self.buffer)
3340                .is_le()
3341            && self
3342                .range
3343                .context
3344                .end
3345                .cmp(&anchor.text_anchor, &self.buffer)
3346                .is_ge()
3347    }
3348}
3349
3350impl ExcerptId {
3351    pub fn min() -> Self {
3352        Self(0)
3353    }
3354
3355    pub fn max() -> Self {
3356        Self(usize::MAX)
3357    }
3358
3359    pub fn to_proto(&self) -> u64 {
3360        self.0 as _
3361    }
3362
3363    pub fn from_proto(proto: u64) -> Self {
3364        Self(proto as _)
3365    }
3366
3367    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
3368        let a = snapshot.excerpt_locator_for_id(*self);
3369        let b = snapshot.excerpt_locator_for_id(*other);
3370        a.cmp(&b).then_with(|| self.0.cmp(&other.0))
3371    }
3372}
3373
3374impl Into<usize> for ExcerptId {
3375    fn into(self) -> usize {
3376        self.0
3377    }
3378}
3379
3380impl fmt::Debug for Excerpt {
3381    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3382        f.debug_struct("Excerpt")
3383            .field("id", &self.id)
3384            .field("locator", &self.locator)
3385            .field("buffer_id", &self.buffer_id)
3386            .field("range", &self.range)
3387            .field("text_summary", &self.text_summary)
3388            .field("has_trailing_newline", &self.has_trailing_newline)
3389            .finish()
3390    }
3391}
3392
3393impl sum_tree::Item for Excerpt {
3394    type Summary = ExcerptSummary;
3395
3396    fn summary(&self) -> Self::Summary {
3397        let mut text = self.text_summary.clone();
3398        if self.has_trailing_newline {
3399            text += TextSummary::from("\n");
3400        }
3401        ExcerptSummary {
3402            excerpt_id: self.id,
3403            excerpt_locator: self.locator.clone(),
3404            max_buffer_row: self.max_buffer_row,
3405            text,
3406        }
3407    }
3408}
3409
3410impl sum_tree::Item for ExcerptIdMapping {
3411    type Summary = ExcerptId;
3412
3413    fn summary(&self) -> Self::Summary {
3414        self.id
3415    }
3416}
3417
3418impl sum_tree::KeyedItem for ExcerptIdMapping {
3419    type Key = ExcerptId;
3420
3421    fn key(&self) -> Self::Key {
3422        self.id
3423    }
3424}
3425
3426impl sum_tree::Summary for ExcerptId {
3427    type Context = ();
3428
3429    fn add_summary(&mut self, other: &Self, _: &()) {
3430        *self = *other;
3431    }
3432}
3433
3434impl sum_tree::Summary for ExcerptSummary {
3435    type Context = ();
3436
3437    fn add_summary(&mut self, summary: &Self, _: &()) {
3438        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
3439        self.excerpt_locator = summary.excerpt_locator.clone();
3440        self.text.add_summary(&summary.text, &());
3441        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
3442    }
3443}
3444
3445impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
3446    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3447        *self += &summary.text;
3448    }
3449}
3450
3451impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
3452    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3453        *self += summary.text.len;
3454    }
3455}
3456
3457impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
3458    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3459        Ord::cmp(self, &cursor_location.text.len)
3460    }
3461}
3462
3463impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
3464    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
3465        Ord::cmp(&Some(self), cursor_location)
3466    }
3467}
3468
3469impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
3470    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3471        Ord::cmp(self, &cursor_location.excerpt_locator)
3472    }
3473}
3474
3475impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
3476    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3477        *self += summary.text.len_utf16;
3478    }
3479}
3480
3481impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
3482    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3483        *self += summary.text.lines;
3484    }
3485}
3486
3487impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
3488    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3489        *self += summary.text.lines_utf16()
3490    }
3491}
3492
3493impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
3494    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3495        *self = Some(&summary.excerpt_locator);
3496    }
3497}
3498
3499impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
3500    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3501        *self = Some(summary.excerpt_id);
3502    }
3503}
3504
3505impl<'a> MultiBufferRows<'a> {
3506    pub fn seek(&mut self, row: u32) {
3507        self.buffer_row_range = 0..0;
3508
3509        self.excerpts
3510            .seek_forward(&Point::new(row, 0), Bias::Right, &());
3511        if self.excerpts.item().is_none() {
3512            self.excerpts.prev(&());
3513
3514            if self.excerpts.item().is_none() && row == 0 {
3515                self.buffer_row_range = 0..1;
3516                return;
3517            }
3518        }
3519
3520        if let Some(excerpt) = self.excerpts.item() {
3521            let overshoot = row - self.excerpts.start().row;
3522            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3523            self.buffer_row_range.start = excerpt_start + overshoot;
3524            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
3525        }
3526    }
3527}
3528
3529impl<'a> Iterator for MultiBufferRows<'a> {
3530    type Item = Option<u32>;
3531
3532    fn next(&mut self) -> Option<Self::Item> {
3533        loop {
3534            if !self.buffer_row_range.is_empty() {
3535                let row = Some(self.buffer_row_range.start);
3536                self.buffer_row_range.start += 1;
3537                return Some(row);
3538            }
3539            self.excerpts.item()?;
3540            self.excerpts.next(&());
3541            let excerpt = self.excerpts.item()?;
3542            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3543            self.buffer_row_range.end =
3544                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
3545        }
3546    }
3547}
3548
3549impl<'a> MultiBufferChunks<'a> {
3550    pub fn offset(&self) -> usize {
3551        self.range.start
3552    }
3553
3554    pub fn seek(&mut self, offset: usize) {
3555        self.range.start = offset;
3556        self.excerpts.seek(&offset, Bias::Right, &());
3557        if let Some(excerpt) = self.excerpts.item() {
3558            self.excerpt_chunks = Some(excerpt.chunks_in_range(
3559                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
3560                self.language_aware,
3561            ));
3562        } else {
3563            self.excerpt_chunks = None;
3564        }
3565    }
3566}
3567
3568impl<'a> Iterator for MultiBufferChunks<'a> {
3569    type Item = Chunk<'a>;
3570
3571    fn next(&mut self) -> Option<Self::Item> {
3572        if self.range.is_empty() {
3573            None
3574        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
3575            self.range.start += chunk.text.len();
3576            Some(chunk)
3577        } else {
3578            self.excerpts.next(&());
3579            let excerpt = self.excerpts.item()?;
3580            self.excerpt_chunks = Some(excerpt.chunks_in_range(
3581                0..self.range.end - self.excerpts.start(),
3582                self.language_aware,
3583            ));
3584            self.next()
3585        }
3586    }
3587}
3588
3589impl<'a> MultiBufferBytes<'a> {
3590    fn consume(&mut self, len: usize) {
3591        self.range.start += len;
3592        self.chunk = &self.chunk[len..];
3593
3594        if !self.range.is_empty() && self.chunk.is_empty() {
3595            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
3596                self.chunk = chunk;
3597            } else {
3598                self.excerpts.next(&());
3599                if let Some(excerpt) = self.excerpts.item() {
3600                    let mut excerpt_bytes =
3601                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
3602                    self.chunk = excerpt_bytes.next().unwrap();
3603                    self.excerpt_bytes = Some(excerpt_bytes);
3604                }
3605            }
3606        }
3607    }
3608}
3609
3610impl<'a> Iterator for MultiBufferBytes<'a> {
3611    type Item = &'a [u8];
3612
3613    fn next(&mut self) -> Option<Self::Item> {
3614        let chunk = self.chunk;
3615        if chunk.is_empty() {
3616            None
3617        } else {
3618            self.consume(chunk.len());
3619            Some(chunk)
3620        }
3621    }
3622}
3623
3624impl<'a> io::Read for MultiBufferBytes<'a> {
3625    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
3626        let len = cmp::min(buf.len(), self.chunk.len());
3627        buf[..len].copy_from_slice(&self.chunk[..len]);
3628        if len > 0 {
3629            self.consume(len);
3630        }
3631        Ok(len)
3632    }
3633}
3634
3635impl<'a> Iterator for ExcerptBytes<'a> {
3636    type Item = &'a [u8];
3637
3638    fn next(&mut self) -> Option<Self::Item> {
3639        if let Some(chunk) = self.content_bytes.next() {
3640            if !chunk.is_empty() {
3641                return Some(chunk);
3642            }
3643        }
3644
3645        if self.footer_height > 0 {
3646            let result = &NEWLINES[..self.footer_height];
3647            self.footer_height = 0;
3648            return Some(result);
3649        }
3650
3651        None
3652    }
3653}
3654
3655impl<'a> Iterator for ExcerptChunks<'a> {
3656    type Item = Chunk<'a>;
3657
3658    fn next(&mut self) -> Option<Self::Item> {
3659        if let Some(chunk) = self.content_chunks.next() {
3660            return Some(chunk);
3661        }
3662
3663        if self.footer_height > 0 {
3664            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
3665            self.footer_height = 0;
3666            return Some(Chunk {
3667                text,
3668                ..Default::default()
3669            });
3670        }
3671
3672        None
3673    }
3674}
3675
3676impl ToOffset for Point {
3677    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3678        snapshot.point_to_offset(*self)
3679    }
3680}
3681
3682impl ToOffset for usize {
3683    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3684        assert!(*self <= snapshot.len(), "offset is out of range");
3685        *self
3686    }
3687}
3688
3689impl ToOffset for OffsetUtf16 {
3690    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3691        snapshot.offset_utf16_to_offset(*self)
3692    }
3693}
3694
3695impl ToOffset for PointUtf16 {
3696    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
3697        snapshot.point_utf16_to_offset(*self)
3698    }
3699}
3700
3701impl ToOffsetUtf16 for OffsetUtf16 {
3702    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
3703        *self
3704    }
3705}
3706
3707impl ToOffsetUtf16 for usize {
3708    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
3709        snapshot.offset_to_offset_utf16(*self)
3710    }
3711}
3712
3713impl ToPoint for usize {
3714    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
3715        snapshot.offset_to_point(*self)
3716    }
3717}
3718
3719impl ToPoint for Point {
3720    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
3721        *self
3722    }
3723}
3724
3725impl ToPointUtf16 for usize {
3726    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
3727        snapshot.offset_to_point_utf16(*self)
3728    }
3729}
3730
3731impl ToPointUtf16 for Point {
3732    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
3733        snapshot.point_to_point_utf16(*self)
3734    }
3735}
3736
3737impl ToPointUtf16 for PointUtf16 {
3738    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
3739        *self
3740    }
3741}
3742
3743fn build_excerpt_ranges<T>(
3744    buffer: &BufferSnapshot,
3745    ranges: &[Range<T>],
3746    context_line_count: u32,
3747) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
3748where
3749    T: text::ToPoint,
3750{
3751    let max_point = buffer.max_point();
3752    let mut range_counts = Vec::new();
3753    let mut excerpt_ranges = Vec::new();
3754    let mut range_iter = ranges
3755        .iter()
3756        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
3757        .peekable();
3758    while let Some(range) = range_iter.next() {
3759        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
3760        let mut excerpt_end = Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
3761        let mut ranges_in_excerpt = 1;
3762
3763        while let Some(next_range) = range_iter.peek() {
3764            if next_range.start.row <= excerpt_end.row + context_line_count {
3765                excerpt_end =
3766                    Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
3767                ranges_in_excerpt += 1;
3768                range_iter.next();
3769            } else {
3770                break;
3771            }
3772        }
3773
3774        excerpt_ranges.push(ExcerptRange {
3775            context: excerpt_start..excerpt_end,
3776            primary: Some(range),
3777        });
3778        range_counts.push(ranges_in_excerpt);
3779    }
3780
3781    (excerpt_ranges, range_counts)
3782}
3783
3784#[cfg(test)]
3785mod tests {
3786    use super::*;
3787    use futures::StreamExt;
3788    use gpui::{AppContext, TestAppContext};
3789    use language::{Buffer, Rope};
3790    use rand::prelude::*;
3791    use settings::Settings;
3792    use std::{env, rc::Rc};
3793    use unindent::Unindent;
3794
3795    use util::test::sample_text;
3796
3797    #[gpui::test]
3798    fn test_singleton(cx: &mut AppContext) {
3799        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
3800        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3801
3802        let snapshot = multibuffer.read(cx).snapshot(cx);
3803        assert_eq!(snapshot.text(), buffer.read(cx).text());
3804
3805        assert_eq!(
3806            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3807            (0..buffer.read(cx).row_count())
3808                .map(Some)
3809                .collect::<Vec<_>>()
3810        );
3811
3812        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
3813        let snapshot = multibuffer.read(cx).snapshot(cx);
3814
3815        assert_eq!(snapshot.text(), buffer.read(cx).text());
3816        assert_eq!(
3817            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3818            (0..buffer.read(cx).row_count())
3819                .map(Some)
3820                .collect::<Vec<_>>()
3821        );
3822    }
3823
3824    #[gpui::test]
3825    fn test_remote(cx: &mut AppContext) {
3826        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
3827        let guest_buffer = cx.add_model(|cx| {
3828            let state = host_buffer.read(cx).to_proto();
3829            let ops = cx
3830                .background()
3831                .block(host_buffer.read(cx).serialize_ops(None, cx));
3832            let mut buffer = Buffer::from_proto(1, state, None).unwrap();
3833            buffer
3834                .apply_ops(
3835                    ops.into_iter()
3836                        .map(|op| language::proto::deserialize_operation(op).unwrap()),
3837                    cx,
3838                )
3839                .unwrap();
3840            buffer
3841        });
3842        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
3843        let snapshot = multibuffer.read(cx).snapshot(cx);
3844        assert_eq!(snapshot.text(), "a");
3845
3846        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
3847        let snapshot = multibuffer.read(cx).snapshot(cx);
3848        assert_eq!(snapshot.text(), "ab");
3849
3850        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
3851        let snapshot = multibuffer.read(cx).snapshot(cx);
3852        assert_eq!(snapshot.text(), "abc");
3853    }
3854
3855    #[gpui::test]
3856    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
3857        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
3858        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
3859        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3860
3861        let events = Rc::new(RefCell::new(Vec::<Event>::new()));
3862        multibuffer.update(cx, |_, cx| {
3863            let events = events.clone();
3864            cx.subscribe(&multibuffer, move |_, _, event, _| {
3865                if let Event::Edited = event {
3866                    events.borrow_mut().push(event.clone())
3867                }
3868            })
3869            .detach();
3870        });
3871
3872        let subscription = multibuffer.update(cx, |multibuffer, cx| {
3873            let subscription = multibuffer.subscribe();
3874            multibuffer.push_excerpts(
3875                buffer_1.clone(),
3876                [ExcerptRange {
3877                    context: Point::new(1, 2)..Point::new(2, 5),
3878                    primary: None,
3879                }],
3880                cx,
3881            );
3882            assert_eq!(
3883                subscription.consume().into_inner(),
3884                [Edit {
3885                    old: 0..0,
3886                    new: 0..10
3887                }]
3888            );
3889
3890            multibuffer.push_excerpts(
3891                buffer_1.clone(),
3892                [ExcerptRange {
3893                    context: Point::new(3, 3)..Point::new(4, 4),
3894                    primary: None,
3895                }],
3896                cx,
3897            );
3898            multibuffer.push_excerpts(
3899                buffer_2.clone(),
3900                [ExcerptRange {
3901                    context: Point::new(3, 1)..Point::new(3, 3),
3902                    primary: None,
3903                }],
3904                cx,
3905            );
3906            assert_eq!(
3907                subscription.consume().into_inner(),
3908                [Edit {
3909                    old: 10..10,
3910                    new: 10..22
3911                }]
3912            );
3913
3914            subscription
3915        });
3916
3917        // Adding excerpts emits an edited event.
3918        assert_eq!(
3919            events.borrow().as_slice(),
3920            &[Event::Edited, Event::Edited, Event::Edited]
3921        );
3922
3923        let snapshot = multibuffer.read(cx).snapshot(cx);
3924        assert_eq!(
3925            snapshot.text(),
3926            concat!(
3927                "bbbb\n",  // Preserve newlines
3928                "ccccc\n", //
3929                "ddd\n",   //
3930                "eeee\n",  //
3931                "jj"       //
3932            )
3933        );
3934        assert_eq!(
3935            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3936            [Some(1), Some(2), Some(3), Some(4), Some(3)]
3937        );
3938        assert_eq!(
3939            snapshot.buffer_rows(2).collect::<Vec<_>>(),
3940            [Some(3), Some(4), Some(3)]
3941        );
3942        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
3943        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
3944
3945        assert_eq!(
3946            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
3947            &[
3948                (0, "bbbb\nccccc".to_string(), true),
3949                (2, "ddd\neeee".to_string(), false),
3950                (4, "jj".to_string(), true),
3951            ]
3952        );
3953        assert_eq!(
3954            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
3955            &[(0, "bbbb\nccccc".to_string(), true)]
3956        );
3957        assert_eq!(
3958            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
3959            &[]
3960        );
3961        assert_eq!(
3962            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
3963            &[]
3964        );
3965        assert_eq!(
3966            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3967            &[(2, "ddd\neeee".to_string(), false)]
3968        );
3969        assert_eq!(
3970            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3971            &[(2, "ddd\neeee".to_string(), false)]
3972        );
3973        assert_eq!(
3974            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
3975            &[(2, "ddd\neeee".to_string(), false)]
3976        );
3977        assert_eq!(
3978            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
3979            &[(4, "jj".to_string(), true)]
3980        );
3981        assert_eq!(
3982            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
3983            &[]
3984        );
3985
3986        buffer_1.update(cx, |buffer, cx| {
3987            let text = "\n";
3988            buffer.edit(
3989                [
3990                    (Point::new(0, 0)..Point::new(0, 0), text),
3991                    (Point::new(2, 1)..Point::new(2, 3), text),
3992                ],
3993                None,
3994                cx,
3995            );
3996        });
3997
3998        let snapshot = multibuffer.read(cx).snapshot(cx);
3999        assert_eq!(
4000            snapshot.text(),
4001            concat!(
4002                "bbbb\n", // Preserve newlines
4003                "c\n",    //
4004                "cc\n",   //
4005                "ddd\n",  //
4006                "eeee\n", //
4007                "jj"      //
4008            )
4009        );
4010
4011        assert_eq!(
4012            subscription.consume().into_inner(),
4013            [Edit {
4014                old: 6..8,
4015                new: 6..7
4016            }]
4017        );
4018
4019        let snapshot = multibuffer.read(cx).snapshot(cx);
4020        assert_eq!(
4021            snapshot.clip_point(Point::new(0, 5), Bias::Left),
4022            Point::new(0, 4)
4023        );
4024        assert_eq!(
4025            snapshot.clip_point(Point::new(0, 5), Bias::Right),
4026            Point::new(0, 4)
4027        );
4028        assert_eq!(
4029            snapshot.clip_point(Point::new(5, 1), Bias::Right),
4030            Point::new(5, 1)
4031        );
4032        assert_eq!(
4033            snapshot.clip_point(Point::new(5, 2), Bias::Right),
4034            Point::new(5, 2)
4035        );
4036        assert_eq!(
4037            snapshot.clip_point(Point::new(5, 3), Bias::Right),
4038            Point::new(5, 2)
4039        );
4040
4041        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
4042            let (buffer_2_excerpt_id, _) =
4043                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
4044            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
4045            multibuffer.snapshot(cx)
4046        });
4047
4048        assert_eq!(
4049            snapshot.text(),
4050            concat!(
4051                "bbbb\n", // Preserve newlines
4052                "c\n",    //
4053                "cc\n",   //
4054                "ddd\n",  //
4055                "eeee",   //
4056            )
4057        );
4058
4059        fn boundaries_in_range(
4060            range: Range<Point>,
4061            snapshot: &MultiBufferSnapshot,
4062        ) -> Vec<(u32, String, bool)> {
4063            snapshot
4064                .excerpt_boundaries_in_range(range)
4065                .map(|boundary| {
4066                    (
4067                        boundary.row,
4068                        boundary
4069                            .buffer
4070                            .text_for_range(boundary.range.context)
4071                            .collect::<String>(),
4072                        boundary.starts_new_buffer,
4073                    )
4074                })
4075                .collect::<Vec<_>>()
4076        }
4077    }
4078
4079    #[gpui::test]
4080    fn test_excerpt_events(cx: &mut AppContext) {
4081        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(10, 3, 'a'), cx));
4082        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(10, 3, 'm'), cx));
4083
4084        let leader_multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4085        let follower_multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4086        let follower_edit_event_count = Rc::new(RefCell::new(0));
4087
4088        follower_multibuffer.update(cx, |_, cx| {
4089            let follower_edit_event_count = follower_edit_event_count.clone();
4090            cx.subscribe(
4091                &leader_multibuffer,
4092                move |follower, _, event, cx| match event.clone() {
4093                    Event::ExcerptsAdded {
4094                        buffer,
4095                        predecessor,
4096                        excerpts,
4097                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
4098                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
4099                    Event::Edited => {
4100                        *follower_edit_event_count.borrow_mut() += 1;
4101                    }
4102                    _ => {}
4103                },
4104            )
4105            .detach();
4106        });
4107
4108        leader_multibuffer.update(cx, |leader, cx| {
4109            leader.push_excerpts(
4110                buffer_1.clone(),
4111                [
4112                    ExcerptRange {
4113                        context: 0..8,
4114                        primary: None,
4115                    },
4116                    ExcerptRange {
4117                        context: 12..16,
4118                        primary: None,
4119                    },
4120                ],
4121                cx,
4122            );
4123            leader.insert_excerpts_after(
4124                leader.excerpt_ids()[0],
4125                buffer_2.clone(),
4126                [
4127                    ExcerptRange {
4128                        context: 0..5,
4129                        primary: None,
4130                    },
4131                    ExcerptRange {
4132                        context: 10..15,
4133                        primary: None,
4134                    },
4135                ],
4136                cx,
4137            )
4138        });
4139        assert_eq!(
4140            leader_multibuffer.read(cx).snapshot(cx).text(),
4141            follower_multibuffer.read(cx).snapshot(cx).text(),
4142        );
4143        assert_eq!(*follower_edit_event_count.borrow(), 2);
4144
4145        leader_multibuffer.update(cx, |leader, cx| {
4146            let excerpt_ids = leader.excerpt_ids();
4147            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
4148        });
4149        assert_eq!(
4150            leader_multibuffer.read(cx).snapshot(cx).text(),
4151            follower_multibuffer.read(cx).snapshot(cx).text(),
4152        );
4153        assert_eq!(*follower_edit_event_count.borrow(), 3);
4154
4155        // Removing an empty set of excerpts is a noop.
4156        leader_multibuffer.update(cx, |leader, cx| {
4157            leader.remove_excerpts([], cx);
4158        });
4159        assert_eq!(
4160            leader_multibuffer.read(cx).snapshot(cx).text(),
4161            follower_multibuffer.read(cx).snapshot(cx).text(),
4162        );
4163        assert_eq!(*follower_edit_event_count.borrow(), 3);
4164
4165        // Adding an empty set of excerpts is a noop.
4166        leader_multibuffer.update(cx, |leader, cx| {
4167            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
4168        });
4169        assert_eq!(
4170            leader_multibuffer.read(cx).snapshot(cx).text(),
4171            follower_multibuffer.read(cx).snapshot(cx).text(),
4172        );
4173        assert_eq!(*follower_edit_event_count.borrow(), 3);
4174
4175        leader_multibuffer.update(cx, |leader, cx| {
4176            leader.clear(cx);
4177        });
4178        assert_eq!(
4179            leader_multibuffer.read(cx).snapshot(cx).text(),
4180            follower_multibuffer.read(cx).snapshot(cx).text(),
4181        );
4182        assert_eq!(*follower_edit_event_count.borrow(), 4);
4183    }
4184
4185    #[gpui::test]
4186    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
4187        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
4188        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4189        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
4190            multibuffer.push_excerpts_with_context_lines(
4191                buffer.clone(),
4192                vec![
4193                    Point::new(3, 2)..Point::new(4, 2),
4194                    Point::new(7, 1)..Point::new(7, 3),
4195                    Point::new(15, 0)..Point::new(15, 0),
4196                ],
4197                2,
4198                cx,
4199            )
4200        });
4201
4202        let snapshot = multibuffer.read(cx).snapshot(cx);
4203        assert_eq!(
4204            snapshot.text(),
4205            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4206        );
4207
4208        assert_eq!(
4209            anchor_ranges
4210                .iter()
4211                .map(|range| range.to_point(&snapshot))
4212                .collect::<Vec<_>>(),
4213            vec![
4214                Point::new(2, 2)..Point::new(3, 2),
4215                Point::new(6, 1)..Point::new(6, 3),
4216                Point::new(12, 0)..Point::new(12, 0)
4217            ]
4218        );
4219    }
4220
4221    #[gpui::test]
4222    async fn test_stream_excerpts_with_context_lines(cx: &mut TestAppContext) {
4223        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
4224        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4225        let (task, anchor_ranges) = multibuffer.update(cx, |multibuffer, cx| {
4226            let snapshot = buffer.read(cx);
4227            let ranges = vec![
4228                snapshot.anchor_before(Point::new(3, 2))..snapshot.anchor_before(Point::new(4, 2)),
4229                snapshot.anchor_before(Point::new(7, 1))..snapshot.anchor_before(Point::new(7, 3)),
4230                snapshot.anchor_before(Point::new(15, 0))
4231                    ..snapshot.anchor_before(Point::new(15, 0)),
4232            ];
4233            multibuffer.stream_excerpts_with_context_lines(vec![(buffer.clone(), ranges)], 2, cx)
4234        });
4235
4236        let anchor_ranges = anchor_ranges.collect::<Vec<_>>().await;
4237        // Ensure task is finished when stream completes.
4238        task.await;
4239
4240        let snapshot = multibuffer.read_with(cx, |multibuffer, cx| multibuffer.snapshot(cx));
4241        assert_eq!(
4242            snapshot.text(),
4243            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4244        );
4245
4246        assert_eq!(
4247            anchor_ranges
4248                .iter()
4249                .map(|range| range.to_point(&snapshot))
4250                .collect::<Vec<_>>(),
4251            vec![
4252                Point::new(2, 2)..Point::new(3, 2),
4253                Point::new(6, 1)..Point::new(6, 3),
4254                Point::new(12, 0)..Point::new(12, 0)
4255            ]
4256        );
4257    }
4258
4259    #[gpui::test]
4260    fn test_empty_multibuffer(cx: &mut AppContext) {
4261        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4262
4263        let snapshot = multibuffer.read(cx).snapshot(cx);
4264        assert_eq!(snapshot.text(), "");
4265        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
4266        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
4267    }
4268
4269    #[gpui::test]
4270    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
4271        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
4272        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4273        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4274        buffer.update(cx, |buffer, cx| {
4275            buffer.edit([(0..0, "X")], None, cx);
4276            buffer.edit([(5..5, "Y")], None, cx);
4277        });
4278        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4279
4280        assert_eq!(old_snapshot.text(), "abcd");
4281        assert_eq!(new_snapshot.text(), "XabcdY");
4282
4283        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4284        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4285        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
4286        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
4287    }
4288
4289    #[gpui::test]
4290    fn test_multibuffer_anchors(cx: &mut AppContext) {
4291        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
4292        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
4293        let multibuffer = cx.add_model(|cx| {
4294            let mut multibuffer = MultiBuffer::new(0);
4295            multibuffer.push_excerpts(
4296                buffer_1.clone(),
4297                [ExcerptRange {
4298                    context: 0..4,
4299                    primary: None,
4300                }],
4301                cx,
4302            );
4303            multibuffer.push_excerpts(
4304                buffer_2.clone(),
4305                [ExcerptRange {
4306                    context: 0..5,
4307                    primary: None,
4308                }],
4309                cx,
4310            );
4311            multibuffer
4312        });
4313        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4314
4315        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
4316        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
4317        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4318        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4319        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4320        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4321
4322        buffer_1.update(cx, |buffer, cx| {
4323            buffer.edit([(0..0, "W")], None, cx);
4324            buffer.edit([(5..5, "X")], None, cx);
4325        });
4326        buffer_2.update(cx, |buffer, cx| {
4327            buffer.edit([(0..0, "Y")], None, cx);
4328            buffer.edit([(6..6, "Z")], None, cx);
4329        });
4330        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4331
4332        assert_eq!(old_snapshot.text(), "abcd\nefghi");
4333        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
4334
4335        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4336        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4337        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
4338        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
4339        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
4340        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
4341        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
4342        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
4343        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
4344        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
4345    }
4346
4347    #[gpui::test]
4348    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
4349        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
4350        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
4351        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4352
4353        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
4354        // Add an excerpt from buffer 1 that spans this new insertion.
4355        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
4356        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
4357            multibuffer
4358                .push_excerpts(
4359                    buffer_1.clone(),
4360                    [ExcerptRange {
4361                        context: 0..7,
4362                        primary: None,
4363                    }],
4364                    cx,
4365                )
4366                .pop()
4367                .unwrap()
4368        });
4369
4370        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
4371        assert_eq!(snapshot_1.text(), "abcd123");
4372
4373        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
4374        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
4375            multibuffer.remove_excerpts([excerpt_id_1], cx);
4376            let mut ids = multibuffer
4377                .push_excerpts(
4378                    buffer_2.clone(),
4379                    [
4380                        ExcerptRange {
4381                            context: 0..4,
4382                            primary: None,
4383                        },
4384                        ExcerptRange {
4385                            context: 6..10,
4386                            primary: None,
4387                        },
4388                        ExcerptRange {
4389                            context: 12..16,
4390                            primary: None,
4391                        },
4392                    ],
4393                    cx,
4394                )
4395                .into_iter();
4396            (ids.next().unwrap(), ids.next().unwrap())
4397        });
4398        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
4399        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
4400
4401        // The old excerpt id doesn't get reused.
4402        assert_ne!(excerpt_id_2, excerpt_id_1);
4403
4404        // Resolve some anchors from the previous snapshot in the new snapshot.
4405        // The current excerpts are from a different buffer, so we don't attempt to
4406        // resolve the old text anchor in the new buffer.
4407        assert_eq!(
4408            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
4409            0
4410        );
4411        assert_eq!(
4412            snapshot_2.summaries_for_anchors::<usize, _>(&[
4413                snapshot_1.anchor_before(2),
4414                snapshot_1.anchor_after(3)
4415            ]),
4416            vec![0, 0]
4417        );
4418
4419        // Refresh anchors from the old snapshot. The return value indicates that both
4420        // anchors lost their original excerpt.
4421        let refresh =
4422            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
4423        assert_eq!(
4424            refresh,
4425            &[
4426                (0, snapshot_2.anchor_before(0), false),
4427                (1, snapshot_2.anchor_after(0), false),
4428            ]
4429        );
4430
4431        // Replace the middle excerpt with a smaller excerpt in buffer 2,
4432        // that intersects the old excerpt.
4433        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
4434            multibuffer.remove_excerpts([excerpt_id_3], cx);
4435            multibuffer
4436                .insert_excerpts_after(
4437                    excerpt_id_2,
4438                    buffer_2.clone(),
4439                    [ExcerptRange {
4440                        context: 5..8,
4441                        primary: None,
4442                    }],
4443                    cx,
4444                )
4445                .pop()
4446                .unwrap()
4447        });
4448
4449        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
4450        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
4451        assert_ne!(excerpt_id_5, excerpt_id_3);
4452
4453        // Resolve some anchors from the previous snapshot in the new snapshot.
4454        // The third anchor can't be resolved, since its excerpt has been removed,
4455        // so it resolves to the same position as its predecessor.
4456        let anchors = [
4457            snapshot_2.anchor_before(0),
4458            snapshot_2.anchor_after(2),
4459            snapshot_2.anchor_after(6),
4460            snapshot_2.anchor_after(14),
4461        ];
4462        assert_eq!(
4463            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
4464            &[0, 2, 9, 13]
4465        );
4466
4467        let new_anchors = snapshot_3.refresh_anchors(&anchors);
4468        assert_eq!(
4469            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
4470            &[(0, true), (1, true), (2, true), (3, true)]
4471        );
4472        assert_eq!(
4473            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
4474            &[0, 2, 7, 13]
4475        );
4476    }
4477
4478    #[gpui::test]
4479    async fn test_diff_hunks_in_range(cx: &mut TestAppContext) {
4480        use git::diff::DiffHunkStatus;
4481
4482        // buffer has two modified hunks with two rows each
4483        let buffer_1 = cx.add_model(|cx| {
4484            let mut buffer = Buffer::new(
4485                0,
4486                "
4487                1.zero
4488                1.ONE
4489                1.TWO
4490                1.three
4491                1.FOUR
4492                1.FIVE
4493                1.six
4494            "
4495                .unindent(),
4496                cx,
4497            );
4498            buffer.set_diff_base(
4499                Some(
4500                    "
4501                1.zero
4502                1.one
4503                1.two
4504                1.three
4505                1.four
4506                1.five
4507                1.six
4508            "
4509                    .unindent(),
4510                ),
4511                cx,
4512            );
4513            buffer
4514        });
4515
4516        // buffer has a deletion hunk and an insertion hunk
4517        let buffer_2 = cx.add_model(|cx| {
4518            let mut buffer = Buffer::new(
4519                0,
4520                "
4521                2.zero
4522                2.one
4523                2.two
4524                2.three
4525                2.four
4526                2.five
4527                2.six
4528            "
4529                .unindent(),
4530                cx,
4531            );
4532            buffer.set_diff_base(
4533                Some(
4534                    "
4535                2.zero
4536                2.one
4537                2.one-and-a-half
4538                2.two
4539                2.three
4540                2.four
4541                2.six
4542            "
4543                    .unindent(),
4544                ),
4545                cx,
4546            );
4547            buffer
4548        });
4549
4550        cx.foreground().run_until_parked();
4551
4552        let multibuffer = cx.add_model(|cx| {
4553            let mut multibuffer = MultiBuffer::new(0);
4554            multibuffer.push_excerpts(
4555                buffer_1.clone(),
4556                [
4557                    // excerpt ends in the middle of a modified hunk
4558                    ExcerptRange {
4559                        context: Point::new(0, 0)..Point::new(1, 5),
4560                        primary: Default::default(),
4561                    },
4562                    // excerpt begins in the middle of a modified hunk
4563                    ExcerptRange {
4564                        context: Point::new(5, 0)..Point::new(6, 5),
4565                        primary: Default::default(),
4566                    },
4567                ],
4568                cx,
4569            );
4570            multibuffer.push_excerpts(
4571                buffer_2.clone(),
4572                [
4573                    // excerpt ends at a deletion
4574                    ExcerptRange {
4575                        context: Point::new(0, 0)..Point::new(1, 5),
4576                        primary: Default::default(),
4577                    },
4578                    // excerpt starts at a deletion
4579                    ExcerptRange {
4580                        context: Point::new(2, 0)..Point::new(2, 5),
4581                        primary: Default::default(),
4582                    },
4583                    // excerpt fully contains a deletion hunk
4584                    ExcerptRange {
4585                        context: Point::new(1, 0)..Point::new(2, 5),
4586                        primary: Default::default(),
4587                    },
4588                    // excerpt fully contains an insertion hunk
4589                    ExcerptRange {
4590                        context: Point::new(4, 0)..Point::new(6, 5),
4591                        primary: Default::default(),
4592                    },
4593                ],
4594                cx,
4595            );
4596            multibuffer
4597        });
4598
4599        let snapshot = multibuffer.read_with(cx, |b, cx| b.snapshot(cx));
4600
4601        assert_eq!(
4602            snapshot.text(),
4603            "
4604                1.zero
4605                1.ONE
4606                1.FIVE
4607                1.six
4608                2.zero
4609                2.one
4610                2.two
4611                2.one
4612                2.two
4613                2.four
4614                2.five
4615                2.six"
4616                .unindent()
4617        );
4618
4619        let expected = [
4620            (DiffHunkStatus::Modified, 1..2),
4621            (DiffHunkStatus::Modified, 2..3),
4622            //TODO: Define better when and where removed hunks show up at range extremities
4623            (DiffHunkStatus::Removed, 6..6),
4624            (DiffHunkStatus::Removed, 8..8),
4625            (DiffHunkStatus::Added, 10..11),
4626        ];
4627
4628        assert_eq!(
4629            snapshot
4630                .git_diff_hunks_in_range(0..12, false)
4631                .map(|hunk| (hunk.status(), hunk.buffer_range))
4632                .collect::<Vec<_>>(),
4633            &expected,
4634        );
4635
4636        assert_eq!(
4637            snapshot
4638                .git_diff_hunks_in_range(0..12, true)
4639                .map(|hunk| (hunk.status(), hunk.buffer_range))
4640                .collect::<Vec<_>>(),
4641            expected
4642                .iter()
4643                .rev()
4644                .cloned()
4645                .collect::<Vec<_>>()
4646                .as_slice(),
4647        );
4648    }
4649
4650    #[gpui::test(iterations = 100)]
4651    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
4652        let operations = env::var("OPERATIONS")
4653            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
4654            .unwrap_or(10);
4655
4656        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
4657        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
4658        let mut excerpt_ids = Vec::<ExcerptId>::new();
4659        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
4660        let mut anchors = Vec::new();
4661        let mut old_versions = Vec::new();
4662
4663        for _ in 0..operations {
4664            match rng.gen_range(0..100) {
4665                0..=19 if !buffers.is_empty() => {
4666                    let buffer = buffers.choose(&mut rng).unwrap();
4667                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
4668                }
4669                20..=29 if !expected_excerpts.is_empty() => {
4670                    let mut ids_to_remove = vec![];
4671                    for _ in 0..rng.gen_range(1..=3) {
4672                        if expected_excerpts.is_empty() {
4673                            break;
4674                        }
4675
4676                        let ix = rng.gen_range(0..expected_excerpts.len());
4677                        ids_to_remove.push(excerpt_ids.remove(ix));
4678                        let (buffer, range) = expected_excerpts.remove(ix);
4679                        let buffer = buffer.read(cx);
4680                        log::info!(
4681                            "Removing excerpt {}: {:?}",
4682                            ix,
4683                            buffer
4684                                .text_for_range(range.to_offset(buffer))
4685                                .collect::<String>(),
4686                        );
4687                    }
4688                    let snapshot = multibuffer.read(cx).read(cx);
4689                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(&b, &snapshot));
4690                    drop(snapshot);
4691                    multibuffer.update(cx, |multibuffer, cx| {
4692                        multibuffer.remove_excerpts(ids_to_remove, cx)
4693                    });
4694                }
4695                30..=39 if !expected_excerpts.is_empty() => {
4696                    let multibuffer = multibuffer.read(cx).read(cx);
4697                    let offset =
4698                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
4699                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
4700                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
4701                    anchors.push(multibuffer.anchor_at(offset, bias));
4702                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
4703                }
4704                40..=44 if !anchors.is_empty() => {
4705                    let multibuffer = multibuffer.read(cx).read(cx);
4706                    let prev_len = anchors.len();
4707                    anchors = multibuffer
4708                        .refresh_anchors(&anchors)
4709                        .into_iter()
4710                        .map(|a| a.1)
4711                        .collect();
4712
4713                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
4714                    // overshoot its boundaries.
4715                    assert_eq!(anchors.len(), prev_len);
4716                    for anchor in &anchors {
4717                        if anchor.excerpt_id == ExcerptId::min()
4718                            || anchor.excerpt_id == ExcerptId::max()
4719                        {
4720                            continue;
4721                        }
4722
4723                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
4724                        assert_eq!(excerpt.id, anchor.excerpt_id);
4725                        assert!(excerpt.contains(anchor));
4726                    }
4727                }
4728                _ => {
4729                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
4730                        let base_text = util::RandomCharIter::new(&mut rng)
4731                            .take(10)
4732                            .collect::<String>();
4733                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
4734                        buffers.last().unwrap()
4735                    } else {
4736                        buffers.choose(&mut rng).unwrap()
4737                    };
4738
4739                    let buffer = buffer_handle.read(cx);
4740                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
4741                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
4742                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
4743                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
4744                    let prev_excerpt_id = excerpt_ids
4745                        .get(prev_excerpt_ix)
4746                        .cloned()
4747                        .unwrap_or_else(ExcerptId::max);
4748                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
4749
4750                    log::info!(
4751                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
4752                        excerpt_ix,
4753                        expected_excerpts.len(),
4754                        buffer_handle.read(cx).remote_id(),
4755                        buffer.text(),
4756                        start_ix..end_ix,
4757                        &buffer.text()[start_ix..end_ix]
4758                    );
4759
4760                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
4761                        multibuffer
4762                            .insert_excerpts_after(
4763                                prev_excerpt_id,
4764                                buffer_handle.clone(),
4765                                [ExcerptRange {
4766                                    context: start_ix..end_ix,
4767                                    primary: None,
4768                                }],
4769                                cx,
4770                            )
4771                            .pop()
4772                            .unwrap()
4773                    });
4774
4775                    excerpt_ids.insert(excerpt_ix, excerpt_id);
4776                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
4777                }
4778            }
4779
4780            if rng.gen_bool(0.3) {
4781                multibuffer.update(cx, |multibuffer, cx| {
4782                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
4783                })
4784            }
4785
4786            let snapshot = multibuffer.read(cx).snapshot(cx);
4787
4788            let mut excerpt_starts = Vec::new();
4789            let mut expected_text = String::new();
4790            let mut expected_buffer_rows = Vec::new();
4791            for (buffer, range) in &expected_excerpts {
4792                let buffer = buffer.read(cx);
4793                let buffer_range = range.to_offset(buffer);
4794
4795                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
4796                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
4797                expected_text.push('\n');
4798
4799                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
4800                    ..=buffer.offset_to_point(buffer_range.end).row;
4801                for row in buffer_row_range {
4802                    expected_buffer_rows.push(Some(row));
4803                }
4804            }
4805            // Remove final trailing newline.
4806            if !expected_excerpts.is_empty() {
4807                expected_text.pop();
4808            }
4809
4810            // Always report one buffer row
4811            if expected_buffer_rows.is_empty() {
4812                expected_buffer_rows.push(Some(0));
4813            }
4814
4815            assert_eq!(snapshot.text(), expected_text);
4816            log::info!("MultiBuffer text: {:?}", expected_text);
4817
4818            assert_eq!(
4819                snapshot.buffer_rows(0).collect::<Vec<_>>(),
4820                expected_buffer_rows,
4821            );
4822
4823            for _ in 0..5 {
4824                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
4825                assert_eq!(
4826                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
4827                    &expected_buffer_rows[start_row..],
4828                    "buffer_rows({})",
4829                    start_row
4830                );
4831            }
4832
4833            assert_eq!(
4834                snapshot.max_buffer_row(),
4835                expected_buffer_rows.into_iter().flatten().max().unwrap()
4836            );
4837
4838            let mut excerpt_starts = excerpt_starts.into_iter();
4839            for (buffer, range) in &expected_excerpts {
4840                let buffer = buffer.read(cx);
4841                let buffer_id = buffer.remote_id();
4842                let buffer_range = range.to_offset(buffer);
4843                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
4844                let buffer_start_point_utf16 =
4845                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
4846
4847                let excerpt_start = excerpt_starts.next().unwrap();
4848                let mut offset = excerpt_start.len;
4849                let mut buffer_offset = buffer_range.start;
4850                let mut point = excerpt_start.lines;
4851                let mut buffer_point = buffer_start_point;
4852                let mut point_utf16 = excerpt_start.lines_utf16();
4853                let mut buffer_point_utf16 = buffer_start_point_utf16;
4854                for ch in buffer
4855                    .snapshot()
4856                    .chunks(buffer_range.clone(), false)
4857                    .flat_map(|c| c.text.chars())
4858                {
4859                    for _ in 0..ch.len_utf8() {
4860                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
4861                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
4862                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
4863                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
4864                        assert_eq!(
4865                            left_offset,
4866                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
4867                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
4868                            offset,
4869                            buffer_id,
4870                            buffer_offset,
4871                        );
4872                        assert_eq!(
4873                            right_offset,
4874                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
4875                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
4876                            offset,
4877                            buffer_id,
4878                            buffer_offset,
4879                        );
4880
4881                        let left_point = snapshot.clip_point(point, Bias::Left);
4882                        let right_point = snapshot.clip_point(point, Bias::Right);
4883                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
4884                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
4885                        assert_eq!(
4886                            left_point,
4887                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
4888                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
4889                            point,
4890                            buffer_id,
4891                            buffer_point,
4892                        );
4893                        assert_eq!(
4894                            right_point,
4895                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
4896                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
4897                            point,
4898                            buffer_id,
4899                            buffer_point,
4900                        );
4901
4902                        assert_eq!(
4903                            snapshot.point_to_offset(left_point),
4904                            left_offset,
4905                            "point_to_offset({:?})",
4906                            left_point,
4907                        );
4908                        assert_eq!(
4909                            snapshot.offset_to_point(left_offset),
4910                            left_point,
4911                            "offset_to_point({:?})",
4912                            left_offset,
4913                        );
4914
4915                        offset += 1;
4916                        buffer_offset += 1;
4917                        if ch == '\n' {
4918                            point += Point::new(1, 0);
4919                            buffer_point += Point::new(1, 0);
4920                        } else {
4921                            point += Point::new(0, 1);
4922                            buffer_point += Point::new(0, 1);
4923                        }
4924                    }
4925
4926                    for _ in 0..ch.len_utf16() {
4927                        let left_point_utf16 =
4928                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
4929                        let right_point_utf16 =
4930                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
4931                        let buffer_left_point_utf16 =
4932                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
4933                        let buffer_right_point_utf16 =
4934                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
4935                        assert_eq!(
4936                            left_point_utf16,
4937                            excerpt_start.lines_utf16()
4938                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
4939                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
4940                            point_utf16,
4941                            buffer_id,
4942                            buffer_point_utf16,
4943                        );
4944                        assert_eq!(
4945                            right_point_utf16,
4946                            excerpt_start.lines_utf16()
4947                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
4948                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
4949                            point_utf16,
4950                            buffer_id,
4951                            buffer_point_utf16,
4952                        );
4953
4954                        if ch == '\n' {
4955                            point_utf16 += PointUtf16::new(1, 0);
4956                            buffer_point_utf16 += PointUtf16::new(1, 0);
4957                        } else {
4958                            point_utf16 += PointUtf16::new(0, 1);
4959                            buffer_point_utf16 += PointUtf16::new(0, 1);
4960                        }
4961                    }
4962                }
4963            }
4964
4965            for (row, line) in expected_text.split('\n').enumerate() {
4966                assert_eq!(
4967                    snapshot.line_len(row as u32),
4968                    line.len() as u32,
4969                    "line_len({}).",
4970                    row
4971                );
4972            }
4973
4974            let text_rope = Rope::from(expected_text.as_str());
4975            for _ in 0..10 {
4976                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
4977                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
4978
4979                let text_for_range = snapshot
4980                    .text_for_range(start_ix..end_ix)
4981                    .collect::<String>();
4982                assert_eq!(
4983                    text_for_range,
4984                    &expected_text[start_ix..end_ix],
4985                    "incorrect text for range {:?}",
4986                    start_ix..end_ix
4987                );
4988
4989                let excerpted_buffer_ranges = multibuffer
4990                    .read(cx)
4991                    .range_to_buffer_ranges(start_ix..end_ix, cx);
4992                let excerpted_buffers_text = excerpted_buffer_ranges
4993                    .into_iter()
4994                    .map(|(buffer, buffer_range)| {
4995                        buffer
4996                            .read(cx)
4997                            .text_for_range(buffer_range)
4998                            .collect::<String>()
4999                    })
5000                    .collect::<Vec<_>>()
5001                    .join("\n");
5002                assert_eq!(excerpted_buffers_text, text_for_range);
5003
5004                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
5005                assert_eq!(
5006                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
5007                    expected_summary,
5008                    "incorrect summary for range {:?}",
5009                    start_ix..end_ix
5010                );
5011            }
5012
5013            // Anchor resolution
5014            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
5015            assert_eq!(anchors.len(), summaries.len());
5016            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
5017                assert!(resolved_offset <= snapshot.len());
5018                assert_eq!(
5019                    snapshot.summary_for_anchor::<usize>(anchor),
5020                    resolved_offset
5021                );
5022            }
5023
5024            for _ in 0..10 {
5025                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5026                assert_eq!(
5027                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
5028                    expected_text[..end_ix].chars().rev().collect::<String>(),
5029                );
5030            }
5031
5032            for _ in 0..10 {
5033                let end_ix = rng.gen_range(0..=text_rope.len());
5034                let start_ix = rng.gen_range(0..=end_ix);
5035                assert_eq!(
5036                    snapshot
5037                        .bytes_in_range(start_ix..end_ix)
5038                        .flatten()
5039                        .copied()
5040                        .collect::<Vec<_>>(),
5041                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
5042                    "bytes_in_range({:?})",
5043                    start_ix..end_ix,
5044                );
5045            }
5046        }
5047
5048        let snapshot = multibuffer.read(cx).snapshot(cx);
5049        for (old_snapshot, subscription) in old_versions {
5050            let edits = subscription.consume().into_inner();
5051
5052            log::info!(
5053                "applying subscription edits to old text: {:?}: {:?}",
5054                old_snapshot.text(),
5055                edits,
5056            );
5057
5058            let mut text = old_snapshot.text();
5059            for edit in edits {
5060                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
5061                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
5062            }
5063            assert_eq!(text.to_string(), snapshot.text());
5064        }
5065    }
5066
5067    #[gpui::test]
5068    fn test_history(cx: &mut AppContext) {
5069        cx.set_global(Settings::test(cx));
5070        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
5071        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
5072        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
5073        let group_interval = multibuffer.read(cx).history.group_interval;
5074        multibuffer.update(cx, |multibuffer, cx| {
5075            multibuffer.push_excerpts(
5076                buffer_1.clone(),
5077                [ExcerptRange {
5078                    context: 0..buffer_1.read(cx).len(),
5079                    primary: None,
5080                }],
5081                cx,
5082            );
5083            multibuffer.push_excerpts(
5084                buffer_2.clone(),
5085                [ExcerptRange {
5086                    context: 0..buffer_2.read(cx).len(),
5087                    primary: None,
5088                }],
5089                cx,
5090            );
5091        });
5092
5093        let mut now = Instant::now();
5094
5095        multibuffer.update(cx, |multibuffer, cx| {
5096            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
5097            multibuffer.edit(
5098                [
5099                    (Point::new(0, 0)..Point::new(0, 0), "A"),
5100                    (Point::new(1, 0)..Point::new(1, 0), "A"),
5101                ],
5102                None,
5103                cx,
5104            );
5105            multibuffer.edit(
5106                [
5107                    (Point::new(0, 1)..Point::new(0, 1), "B"),
5108                    (Point::new(1, 1)..Point::new(1, 1), "B"),
5109                ],
5110                None,
5111                cx,
5112            );
5113            multibuffer.end_transaction_at(now, cx);
5114            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5115
5116            // Edit buffer 1 through the multibuffer
5117            now += 2 * group_interval;
5118            multibuffer.start_transaction_at(now, cx);
5119            multibuffer.edit([(2..2, "C")], None, cx);
5120            multibuffer.end_transaction_at(now, cx);
5121            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
5122
5123            // Edit buffer 1 independently
5124            buffer_1.update(cx, |buffer_1, cx| {
5125                buffer_1.start_transaction_at(now);
5126                buffer_1.edit([(3..3, "D")], None, cx);
5127                buffer_1.end_transaction_at(now, cx);
5128
5129                now += 2 * group_interval;
5130                buffer_1.start_transaction_at(now);
5131                buffer_1.edit([(4..4, "E")], None, cx);
5132                buffer_1.end_transaction_at(now, cx);
5133            });
5134            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5135
5136            // An undo in the multibuffer undoes the multibuffer transaction
5137            // and also any individual buffer edits that have occured since
5138            // that transaction.
5139            multibuffer.undo(cx);
5140            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5141
5142            multibuffer.undo(cx);
5143            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5144
5145            multibuffer.redo(cx);
5146            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5147
5148            multibuffer.redo(cx);
5149            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5150
5151            // Undo buffer 2 independently.
5152            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
5153            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
5154
5155            // An undo in the multibuffer undoes the components of the
5156            // the last multibuffer transaction that are not already undone.
5157            multibuffer.undo(cx);
5158            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
5159
5160            multibuffer.undo(cx);
5161            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5162
5163            multibuffer.redo(cx);
5164            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5165
5166            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
5167            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5168
5169            // Redo stack gets cleared after an edit.
5170            now += 2 * group_interval;
5171            multibuffer.start_transaction_at(now, cx);
5172            multibuffer.edit([(0..0, "X")], None, cx);
5173            multibuffer.end_transaction_at(now, cx);
5174            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5175            multibuffer.redo(cx);
5176            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5177            multibuffer.undo(cx);
5178            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5179            multibuffer.undo(cx);
5180            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5181
5182            // Transactions can be grouped manually.
5183            multibuffer.redo(cx);
5184            multibuffer.redo(cx);
5185            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5186            multibuffer.group_until_transaction(transaction_1, cx);
5187            multibuffer.undo(cx);
5188            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5189            multibuffer.redo(cx);
5190            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5191        });
5192    }
5193}