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