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