1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::{anyhow, Result};
   5use clock::ReplicaId;
   6use collections::{BTreeMap, Bound, HashMap, HashSet};
   7use futures::{channel::mpsc, SinkExt};
   8use git::diff::DiffHunk;
   9use gpui::{AppContext, EventEmitter, Model, ModelContext};
  10pub use language::Completion;
  11use language::{
  12    char_kind,
  13    language_settings::{language_settings, LanguageSettings},
  14    AutoindentMode, Buffer, BufferChunks, BufferSnapshot, Capability, CharKind, Chunk, CursorShape,
  15    DiagnosticEntry, File, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16,
  16    Outline, OutlineItem, Point, PointUtf16, Selection, TextDimension, ToOffset as _,
  17    ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _, TransactionId, Unclipped,
  18};
  19use std::{
  20    borrow::Cow,
  21    cell::{Ref, RefCell},
  22    cmp, fmt,
  23    future::Future,
  24    io,
  25    iter::{self, FromIterator},
  26    mem,
  27    ops::{Range, RangeBounds, Sub},
  28    str,
  29    sync::Arc,
  30    time::{Duration, Instant},
  31};
  32use sum_tree::{Bias, Cursor, SumTree};
  33use text::{
  34    locator::Locator,
  35    subscription::{Subscription, Topic},
  36    BufferId, Edit, TextSummary,
  37};
  38use theme::SyntaxTheme;
  39
  40use util::post_inc;
  41
  42#[cfg(any(test, feature = "test-support"))]
  43use gpui::Context;
  44
  45const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  46
  47#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  48pub struct ExcerptId(usize);
  49
  50/// One or more [`Buffers`](Buffer) being edited in a single view.
  51///
  52/// See <https://zed.dev/features#multi-buffers>
  53pub struct MultiBuffer {
  54    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  55    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  56    snapshot: RefCell<MultiBufferSnapshot>,
  57    /// Contains the state of the buffers being edited
  58    buffers: RefCell<HashMap<BufferId, BufferState>>,
  59    subscriptions: Topic,
  60    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  61    singleton: bool,
  62    replica_id: ReplicaId,
  63    history: History,
  64    title: Option<String>,
  65    capability: Capability,
  66}
  67
  68#[derive(Clone, Debug, PartialEq, Eq)]
  69pub enum Event {
  70    ExcerptsAdded {
  71        buffer: Model<Buffer>,
  72        predecessor: ExcerptId,
  73        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  74    },
  75    ExcerptsRemoved {
  76        ids: Vec<ExcerptId>,
  77    },
  78    ExcerptsEdited {
  79        ids: Vec<ExcerptId>,
  80    },
  81    Edited {
  82        singleton_buffer_edited: bool,
  83    },
  84    TransactionUndone {
  85        transaction_id: TransactionId,
  86    },
  87    Reloaded,
  88    DiffBaseChanged,
  89    LanguageChanged,
  90    CapabilityChanged,
  91    Reparsed,
  92    Saved,
  93    FileHandleChanged,
  94    Closed,
  95    DirtyChanged,
  96    DiagnosticsUpdated,
  97}
  98
  99#[derive(Clone)]
 100struct History {
 101    next_transaction_id: TransactionId,
 102    undo_stack: Vec<Transaction>,
 103    redo_stack: Vec<Transaction>,
 104    transaction_depth: usize,
 105    group_interval: Duration,
 106}
 107
 108#[derive(Clone)]
 109struct Transaction {
 110    id: TransactionId,
 111    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 112    first_edit_at: Instant,
 113    last_edit_at: Instant,
 114    suppress_grouping: bool,
 115}
 116
 117pub trait ToOffset: 'static + fmt::Debug {
 118    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 119}
 120
 121pub trait ToOffsetUtf16: 'static + fmt::Debug {
 122    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 123}
 124
 125pub trait ToPoint: 'static + fmt::Debug {
 126    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 127}
 128
 129pub trait ToPointUtf16: 'static + fmt::Debug {
 130    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 131}
 132
 133struct BufferState {
 134    buffer: Model<Buffer>,
 135    last_version: clock::Global,
 136    last_parse_count: usize,
 137    last_selections_update_count: usize,
 138    last_diagnostics_update_count: usize,
 139    last_file_update_count: usize,
 140    last_git_diff_update_count: usize,
 141    excerpts: Vec<Locator>,
 142    _subscriptions: [gpui::Subscription; 2],
 143}
 144
 145/// The contents of a [`MultiBuffer`] at a single point in time.
 146#[derive(Clone, Default)]
 147pub struct MultiBufferSnapshot {
 148    singleton: bool,
 149    excerpts: SumTree<Excerpt>,
 150    excerpt_ids: SumTree<ExcerptIdMapping>,
 151    parse_count: usize,
 152    diagnostics_update_count: usize,
 153    trailing_excerpt_update_count: usize,
 154    git_diff_update_count: usize,
 155    edit_count: usize,
 156    is_dirty: bool,
 157    has_conflict: bool,
 158}
 159
 160/// A boundary between [`Excerpt`]s in a [`MultiBuffer`]
 161pub struct ExcerptBoundary {
 162    pub id: ExcerptId,
 163    /// The row in the `MultiBuffer` where the boundary is located
 164    pub row: u32,
 165    pub buffer: BufferSnapshot,
 166    pub range: ExcerptRange<text::Anchor>,
 167    /// It's possible to have multiple excerpts in the same buffer,
 168    /// and they are rendered together without a new File header.
 169    ///
 170    /// This flag indicates that the excerpt is the first one in the buffer.
 171    pub starts_new_buffer: bool,
 172}
 173
 174/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 175#[derive(Clone)]
 176struct Excerpt {
 177    /// The unique identifier for this excerpt
 178    id: ExcerptId,
 179    /// The location of the excerpt in the [`MultiBuffer`]
 180    locator: Locator,
 181    /// The buffer being excerpted
 182    buffer_id: BufferId,
 183    /// A snapshot of the buffer being excerpted
 184    buffer: BufferSnapshot,
 185    /// The range of the buffer to be shown in the excerpt
 186    range: ExcerptRange<text::Anchor>,
 187    /// The last row in the excerpted slice of the buffer
 188    max_buffer_row: u32,
 189    /// A summary of the text in the excerpt
 190    text_summary: TextSummary,
 191    has_trailing_newline: bool,
 192}
 193
 194/// A public view into an [`Excerpt`] in a [`MultiBuffer`].
 195///
 196/// Contains methods for getting the [`Buffer`] of the excerpt,
 197/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 198#[derive(Copy, Clone)]
 199pub struct MultiBufferExcerpt<'a> {
 200    excerpt: &'a Excerpt,
 201    excerpt_offset: usize,
 202}
 203
 204#[derive(Clone, Debug)]
 205struct ExcerptIdMapping {
 206    id: ExcerptId,
 207    locator: Locator,
 208}
 209
 210/// A range of text from a single [`Buffer`], to be shown as an [`Excerpt`].
 211/// These ranges are relative to the buffer itself
 212#[derive(Clone, Debug, Eq, PartialEq)]
 213pub struct ExcerptRange<T> {
 214    /// The full range of text to be shown in the excerpt.
 215    pub context: Range<T>,
 216    /// The primary range of text to be highlighted in the excerpt.
 217    /// In a multi-buffer search, this would be the text that matched the search
 218    pub primary: Option<Range<T>>,
 219}
 220
 221#[derive(Clone, Debug, Default)]
 222struct ExcerptSummary {
 223    excerpt_id: ExcerptId,
 224    /// The location of the last [`Excerpt`] being summarized
 225    excerpt_locator: Locator,
 226    /// The maximum row of the [`Excerpt`]s being summarized
 227    max_buffer_row: u32,
 228    text: TextSummary,
 229}
 230
 231#[derive(Clone)]
 232pub struct MultiBufferRows<'a> {
 233    buffer_row_range: Range<u32>,
 234    excerpts: Cursor<'a, Excerpt, Point>,
 235}
 236
 237pub struct MultiBufferChunks<'a> {
 238    range: Range<usize>,
 239    excerpts: Cursor<'a, Excerpt, usize>,
 240    excerpt_chunks: Option<ExcerptChunks<'a>>,
 241    language_aware: bool,
 242}
 243
 244pub struct MultiBufferBytes<'a> {
 245    range: Range<usize>,
 246    excerpts: Cursor<'a, Excerpt, usize>,
 247    excerpt_bytes: Option<ExcerptBytes<'a>>,
 248    chunk: &'a [u8],
 249}
 250
 251pub struct ReversedMultiBufferBytes<'a> {
 252    range: Range<usize>,
 253    excerpts: Cursor<'a, Excerpt, usize>,
 254    excerpt_bytes: Option<ExcerptBytes<'a>>,
 255    chunk: &'a [u8],
 256}
 257
 258struct ExcerptChunks<'a> {
 259    content_chunks: BufferChunks<'a>,
 260    footer_height: usize,
 261}
 262
 263struct ExcerptBytes<'a> {
 264    content_bytes: text::Bytes<'a>,
 265    footer_height: usize,
 266}
 267
 268impl MultiBuffer {
 269    pub fn new(replica_id: ReplicaId, capability: Capability) -> Self {
 270        Self {
 271            snapshot: Default::default(),
 272            buffers: Default::default(),
 273            subscriptions: Default::default(),
 274            singleton: false,
 275            capability,
 276            replica_id,
 277            history: History {
 278                next_transaction_id: Default::default(),
 279                undo_stack: Default::default(),
 280                redo_stack: Default::default(),
 281                transaction_depth: 0,
 282                group_interval: Duration::from_millis(300),
 283            },
 284            title: Default::default(),
 285        }
 286    }
 287
 288    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 289        let mut buffers = HashMap::default();
 290        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 291            buffers.insert(
 292                *buffer_id,
 293                BufferState {
 294                    buffer: buffer_state.buffer.clone(),
 295                    last_version: buffer_state.last_version.clone(),
 296                    last_parse_count: buffer_state.last_parse_count,
 297                    last_selections_update_count: buffer_state.last_selections_update_count,
 298                    last_diagnostics_update_count: buffer_state.last_diagnostics_update_count,
 299                    last_file_update_count: buffer_state.last_file_update_count,
 300                    last_git_diff_update_count: buffer_state.last_git_diff_update_count,
 301                    excerpts: buffer_state.excerpts.clone(),
 302                    _subscriptions: [
 303                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 304                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 305                    ],
 306                },
 307            );
 308        }
 309        Self {
 310            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 311            buffers: RefCell::new(buffers),
 312            subscriptions: Default::default(),
 313            singleton: self.singleton,
 314            capability: self.capability,
 315            replica_id: self.replica_id,
 316            history: self.history.clone(),
 317            title: self.title.clone(),
 318        }
 319    }
 320
 321    pub fn with_title(mut self, title: String) -> Self {
 322        self.title = Some(title);
 323        self
 324    }
 325
 326    pub fn read_only(&self) -> bool {
 327        self.capability == Capability::ReadOnly
 328    }
 329
 330    pub fn singleton(buffer: Model<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 331        let mut this = Self::new(buffer.read(cx).replica_id(), buffer.read(cx).capability());
 332        this.singleton = true;
 333        this.push_excerpts(
 334            buffer,
 335            [ExcerptRange {
 336                context: text::Anchor::MIN..text::Anchor::MAX,
 337                primary: None,
 338            }],
 339            cx,
 340        );
 341        this.snapshot.borrow_mut().singleton = true;
 342        this
 343    }
 344
 345    pub fn replica_id(&self) -> ReplicaId {
 346        self.replica_id
 347    }
 348
 349    /// Returns an up-to-date snapshot of the MultiBuffer.
 350    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 351        self.sync(cx);
 352        self.snapshot.borrow().clone()
 353    }
 354
 355    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 356        self.sync(cx);
 357        self.snapshot.borrow()
 358    }
 359
 360    pub fn as_singleton(&self) -> Option<Model<Buffer>> {
 361        if self.singleton {
 362            return Some(
 363                self.buffers
 364                    .borrow()
 365                    .values()
 366                    .next()
 367                    .unwrap()
 368                    .buffer
 369                    .clone(),
 370            );
 371        } else {
 372            None
 373        }
 374    }
 375
 376    pub fn is_singleton(&self) -> bool {
 377        self.singleton
 378    }
 379
 380    pub fn subscribe(&mut self) -> Subscription {
 381        self.subscriptions.subscribe()
 382    }
 383
 384    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 385        self.read(cx).is_dirty()
 386    }
 387
 388    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 389        self.read(cx).has_conflict()
 390    }
 391
 392    // The `is_empty` signature doesn't match what clippy expects
 393    #[allow(clippy::len_without_is_empty)]
 394    pub fn len(&self, cx: &AppContext) -> usize {
 395        self.read(cx).len()
 396    }
 397
 398    pub fn is_empty(&self, cx: &AppContext) -> bool {
 399        self.len(cx) != 0
 400    }
 401
 402    pub fn symbols_containing<T: ToOffset>(
 403        &self,
 404        offset: T,
 405        theme: Option<&SyntaxTheme>,
 406        cx: &AppContext,
 407    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 408        self.read(cx).symbols_containing(offset, theme)
 409    }
 410
 411    pub fn edit<I, S, T>(
 412        &mut self,
 413        edits: I,
 414        mut autoindent_mode: Option<AutoindentMode>,
 415        cx: &mut ModelContext<Self>,
 416    ) where
 417        I: IntoIterator<Item = (Range<S>, T)>,
 418        S: ToOffset,
 419        T: Into<Arc<str>>,
 420    {
 421        if self.buffers.borrow().is_empty() {
 422            return;
 423        }
 424
 425        let snapshot = self.read(cx);
 426        let edits = edits.into_iter().map(|(range, new_text)| {
 427            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 428            if range.start > range.end {
 429                mem::swap(&mut range.start, &mut range.end);
 430            }
 431            (range, new_text)
 432        });
 433
 434        if let Some(buffer) = self.as_singleton() {
 435            return buffer.update(cx, |buffer, cx| {
 436                buffer.edit(edits, autoindent_mode, cx);
 437            });
 438        }
 439
 440        let original_indent_columns = match &mut autoindent_mode {
 441            Some(AutoindentMode::Block {
 442                original_indent_columns,
 443            }) => mem::take(original_indent_columns),
 444            _ => Default::default(),
 445        };
 446
 447        struct BufferEdit {
 448            range: Range<usize>,
 449            new_text: Arc<str>,
 450            is_insertion: bool,
 451            original_indent_column: u32,
 452        }
 453        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 454        let mut edited_excerpt_ids = Vec::new();
 455        let mut cursor = snapshot.excerpts.cursor::<usize>();
 456        for (ix, (range, new_text)) in edits.enumerate() {
 457            let new_text: Arc<str> = new_text.into();
 458            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 459            cursor.seek(&range.start, Bias::Right, &());
 460            if cursor.item().is_none() && range.start == *cursor.start() {
 461                cursor.prev(&());
 462            }
 463            let start_excerpt = cursor.item().expect("start offset out of bounds");
 464            let start_overshoot = range.start - cursor.start();
 465            let buffer_start = start_excerpt
 466                .range
 467                .context
 468                .start
 469                .to_offset(&start_excerpt.buffer)
 470                + start_overshoot;
 471            edited_excerpt_ids.push(start_excerpt.id);
 472
 473            cursor.seek(&range.end, Bias::Right, &());
 474            if cursor.item().is_none() && range.end == *cursor.start() {
 475                cursor.prev(&());
 476            }
 477            let end_excerpt = cursor.item().expect("end offset out of bounds");
 478            let end_overshoot = range.end - cursor.start();
 479            let buffer_end = end_excerpt
 480                .range
 481                .context
 482                .start
 483                .to_offset(&end_excerpt.buffer)
 484                + end_overshoot;
 485
 486            if start_excerpt.id == end_excerpt.id {
 487                buffer_edits
 488                    .entry(start_excerpt.buffer_id)
 489                    .or_insert(Vec::new())
 490                    .push(BufferEdit {
 491                        range: buffer_start..buffer_end,
 492                        new_text,
 493                        is_insertion: true,
 494                        original_indent_column,
 495                    });
 496            } else {
 497                edited_excerpt_ids.push(end_excerpt.id);
 498                let start_excerpt_range = buffer_start
 499                    ..start_excerpt
 500                        .range
 501                        .context
 502                        .end
 503                        .to_offset(&start_excerpt.buffer);
 504                let end_excerpt_range = end_excerpt
 505                    .range
 506                    .context
 507                    .start
 508                    .to_offset(&end_excerpt.buffer)
 509                    ..buffer_end;
 510                buffer_edits
 511                    .entry(start_excerpt.buffer_id)
 512                    .or_insert(Vec::new())
 513                    .push(BufferEdit {
 514                        range: start_excerpt_range,
 515                        new_text: new_text.clone(),
 516                        is_insertion: true,
 517                        original_indent_column,
 518                    });
 519                buffer_edits
 520                    .entry(end_excerpt.buffer_id)
 521                    .or_insert(Vec::new())
 522                    .push(BufferEdit {
 523                        range: end_excerpt_range,
 524                        new_text: new_text.clone(),
 525                        is_insertion: false,
 526                        original_indent_column,
 527                    });
 528
 529                cursor.seek(&range.start, Bias::Right, &());
 530                cursor.next(&());
 531                while let Some(excerpt) = cursor.item() {
 532                    if excerpt.id == end_excerpt.id {
 533                        break;
 534                    }
 535                    buffer_edits
 536                        .entry(excerpt.buffer_id)
 537                        .or_insert(Vec::new())
 538                        .push(BufferEdit {
 539                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 540                            new_text: new_text.clone(),
 541                            is_insertion: false,
 542                            original_indent_column,
 543                        });
 544                    edited_excerpt_ids.push(excerpt.id);
 545                    cursor.next(&());
 546                }
 547            }
 548        }
 549
 550        drop(cursor);
 551        drop(snapshot);
 552        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 553        fn tail(
 554            this: &mut MultiBuffer,
 555            buffer_edits: HashMap<BufferId, Vec<BufferEdit>>,
 556            autoindent_mode: Option<AutoindentMode>,
 557            edited_excerpt_ids: Vec<ExcerptId>,
 558            cx: &mut ModelContext<MultiBuffer>,
 559        ) {
 560            for (buffer_id, mut edits) in buffer_edits {
 561                edits.sort_unstable_by_key(|edit| edit.range.start);
 562                this.buffers.borrow()[&buffer_id]
 563                    .buffer
 564                    .update(cx, |buffer, cx| {
 565                        let mut edits = edits.into_iter().peekable();
 566                        let mut insertions = Vec::new();
 567                        let mut original_indent_columns = Vec::new();
 568                        let mut deletions = Vec::new();
 569                        let empty_str: Arc<str> = "".into();
 570                        while let Some(BufferEdit {
 571                            mut range,
 572                            new_text,
 573                            mut is_insertion,
 574                            original_indent_column,
 575                        }) = edits.next()
 576                        {
 577                            while let Some(BufferEdit {
 578                                range: next_range,
 579                                is_insertion: next_is_insertion,
 580                                ..
 581                            }) = edits.peek()
 582                            {
 583                                if range.end >= next_range.start {
 584                                    range.end = cmp::max(next_range.end, range.end);
 585                                    is_insertion |= *next_is_insertion;
 586                                    edits.next();
 587                                } else {
 588                                    break;
 589                                }
 590                            }
 591
 592                            if is_insertion {
 593                                original_indent_columns.push(original_indent_column);
 594                                insertions.push((
 595                                    buffer.anchor_before(range.start)
 596                                        ..buffer.anchor_before(range.end),
 597                                    new_text.clone(),
 598                                ));
 599                            } else if !range.is_empty() {
 600                                deletions.push((
 601                                    buffer.anchor_before(range.start)
 602                                        ..buffer.anchor_before(range.end),
 603                                    empty_str.clone(),
 604                                ));
 605                            }
 606                        }
 607
 608                        let deletion_autoindent_mode =
 609                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 610                                Some(AutoindentMode::Block {
 611                                    original_indent_columns: Default::default(),
 612                                })
 613                            } else {
 614                                None
 615                            };
 616                        let insertion_autoindent_mode =
 617                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 618                                Some(AutoindentMode::Block {
 619                                    original_indent_columns,
 620                                })
 621                            } else {
 622                                None
 623                            };
 624
 625                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 626                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 627                    })
 628            }
 629
 630            cx.emit(Event::ExcerptsEdited {
 631                ids: edited_excerpt_ids,
 632            });
 633        }
 634        tail(self, buffer_edits, autoindent_mode, edited_excerpt_ids, cx);
 635    }
 636
 637    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 638        self.start_transaction_at(Instant::now(), cx)
 639    }
 640
 641    pub fn start_transaction_at(
 642        &mut self,
 643        now: Instant,
 644        cx: &mut ModelContext<Self>,
 645    ) -> Option<TransactionId> {
 646        if let Some(buffer) = self.as_singleton() {
 647            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 648        }
 649
 650        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 651            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 652        }
 653        self.history.start_transaction(now)
 654    }
 655
 656    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 657        self.end_transaction_at(Instant::now(), cx)
 658    }
 659
 660    pub fn end_transaction_at(
 661        &mut self,
 662        now: Instant,
 663        cx: &mut ModelContext<Self>,
 664    ) -> Option<TransactionId> {
 665        if let Some(buffer) = self.as_singleton() {
 666            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 667        }
 668
 669        let mut buffer_transactions = HashMap::default();
 670        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 671            if let Some(transaction_id) =
 672                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 673            {
 674                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 675            }
 676        }
 677
 678        if self.history.end_transaction(now, buffer_transactions) {
 679            let transaction_id = self.history.group().unwrap();
 680            Some(transaction_id)
 681        } else {
 682            None
 683        }
 684    }
 685
 686    pub fn merge_transactions(
 687        &mut self,
 688        transaction: TransactionId,
 689        destination: TransactionId,
 690        cx: &mut ModelContext<Self>,
 691    ) {
 692        if let Some(buffer) = self.as_singleton() {
 693            buffer.update(cx, |buffer, _| {
 694                buffer.merge_transactions(transaction, destination)
 695            });
 696        } else {
 697            if let Some(transaction) = self.history.forget(transaction) {
 698                if let Some(destination) = self.history.transaction_mut(destination) {
 699                    for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
 700                        if let Some(destination_buffer_transaction_id) =
 701                            destination.buffer_transactions.get(&buffer_id)
 702                        {
 703                            if let Some(state) = self.buffers.borrow().get(&buffer_id) {
 704                                state.buffer.update(cx, |buffer, _| {
 705                                    buffer.merge_transactions(
 706                                        buffer_transaction_id,
 707                                        *destination_buffer_transaction_id,
 708                                    )
 709                                });
 710                            }
 711                        } else {
 712                            destination
 713                                .buffer_transactions
 714                                .insert(buffer_id, buffer_transaction_id);
 715                        }
 716                    }
 717                }
 718            }
 719        }
 720    }
 721
 722    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 723        self.history.finalize_last_transaction();
 724        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 725            buffer.update(cx, |buffer, _| {
 726                buffer.finalize_last_transaction();
 727            });
 728        }
 729    }
 730
 731    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &mut ModelContext<Self>)
 732    where
 733        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
 734    {
 735        self.history
 736            .push_transaction(buffer_transactions, Instant::now(), cx);
 737        self.history.finalize_last_transaction();
 738    }
 739
 740    pub fn group_until_transaction(
 741        &mut self,
 742        transaction_id: TransactionId,
 743        cx: &mut ModelContext<Self>,
 744    ) {
 745        if let Some(buffer) = self.as_singleton() {
 746            buffer.update(cx, |buffer, _| {
 747                buffer.group_until_transaction(transaction_id)
 748            });
 749        } else {
 750            self.history.group_until(transaction_id);
 751        }
 752    }
 753
 754    pub fn set_active_selections(
 755        &mut self,
 756        selections: &[Selection<Anchor>],
 757        line_mode: bool,
 758        cursor_shape: CursorShape,
 759        cx: &mut ModelContext<Self>,
 760    ) {
 761        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
 762            Default::default();
 763        let snapshot = self.read(cx);
 764        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
 765        for selection in selections {
 766            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 767            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 768
 769            cursor.seek(&Some(start_locator), Bias::Left, &());
 770            while let Some(excerpt) = cursor.item() {
 771                if excerpt.locator > *end_locator {
 772                    break;
 773                }
 774
 775                let mut start = excerpt.range.context.start;
 776                let mut end = excerpt.range.context.end;
 777                if excerpt.id == selection.start.excerpt_id {
 778                    start = selection.start.text_anchor;
 779                }
 780                if excerpt.id == selection.end.excerpt_id {
 781                    end = selection.end.text_anchor;
 782                }
 783                selections_by_buffer
 784                    .entry(excerpt.buffer_id)
 785                    .or_default()
 786                    .push(Selection {
 787                        id: selection.id,
 788                        start,
 789                        end,
 790                        reversed: selection.reversed,
 791                        goal: selection.goal,
 792                    });
 793
 794                cursor.next(&());
 795            }
 796        }
 797
 798        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 799            if !selections_by_buffer.contains_key(buffer_id) {
 800                buffer_state
 801                    .buffer
 802                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 803            }
 804        }
 805
 806        for (buffer_id, mut selections) in selections_by_buffer {
 807            self.buffers.borrow()[&buffer_id]
 808                .buffer
 809                .update(cx, |buffer, cx| {
 810                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
 811                    let mut selections = selections.into_iter().peekable();
 812                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 813                        let mut selection = selections.next()?;
 814                        while let Some(next_selection) = selections.peek() {
 815                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
 816                                let next_selection = selections.next().unwrap();
 817                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
 818                                    selection.end = next_selection.end;
 819                                }
 820                            } else {
 821                                break;
 822                            }
 823                        }
 824                        Some(selection)
 825                    }));
 826                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
 827                });
 828        }
 829    }
 830
 831    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 832        for buffer in self.buffers.borrow().values() {
 833            buffer
 834                .buffer
 835                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 836        }
 837    }
 838
 839    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 840        let mut transaction_id = None;
 841        if let Some(buffer) = self.as_singleton() {
 842            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
 843        } else {
 844            while let Some(transaction) = self.history.pop_undo() {
 845                let mut undone = false;
 846                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 847                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 848                        undone |= buffer.update(cx, |buffer, cx| {
 849                            let undo_to = *buffer_transaction_id;
 850                            if let Some(entry) = buffer.peek_undo_stack() {
 851                                *buffer_transaction_id = entry.transaction_id();
 852                            }
 853                            buffer.undo_to_transaction(undo_to, cx)
 854                        });
 855                    }
 856                }
 857
 858                if undone {
 859                    transaction_id = Some(transaction.id);
 860                    break;
 861                }
 862            }
 863        }
 864
 865        if let Some(transaction_id) = transaction_id {
 866            cx.emit(Event::TransactionUndone { transaction_id });
 867        }
 868
 869        transaction_id
 870    }
 871
 872    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 873        if let Some(buffer) = self.as_singleton() {
 874            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 875        }
 876
 877        while let Some(transaction) = self.history.pop_redo() {
 878            let mut redone = false;
 879            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 880                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 881                    redone |= buffer.update(cx, |buffer, cx| {
 882                        let redo_to = *buffer_transaction_id;
 883                        if let Some(entry) = buffer.peek_redo_stack() {
 884                            *buffer_transaction_id = entry.transaction_id();
 885                        }
 886                        buffer.redo_to_transaction(redo_to, cx)
 887                    });
 888                }
 889            }
 890
 891            if redone {
 892                return Some(transaction.id);
 893            }
 894        }
 895
 896        None
 897    }
 898
 899    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
 900        if let Some(buffer) = self.as_singleton() {
 901            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
 902        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
 903            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
 904                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 905                    buffer.update(cx, |buffer, cx| {
 906                        buffer.undo_transaction(*transaction_id, cx)
 907                    });
 908                }
 909            }
 910        }
 911    }
 912
 913    pub fn stream_excerpts_with_context_lines(
 914        &mut self,
 915        buffer: Model<Buffer>,
 916        ranges: Vec<Range<text::Anchor>>,
 917        context_line_count: u32,
 918        cx: &mut ModelContext<Self>,
 919    ) -> mpsc::Receiver<Range<Anchor>> {
 920        let (buffer_id, buffer_snapshot) =
 921            buffer.update(cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
 922
 923        let (mut tx, rx) = mpsc::channel(256);
 924        cx.spawn(move |this, mut cx| async move {
 925            let mut excerpt_ranges = Vec::new();
 926            let mut range_counts = Vec::new();
 927            cx.background_executor()
 928                .scoped(|scope| {
 929                    scope.spawn(async {
 930                        let (ranges, counts) =
 931                            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 932                        excerpt_ranges = ranges;
 933                        range_counts = counts;
 934                    });
 935                })
 936                .await;
 937
 938            let mut ranges = ranges.into_iter();
 939            let mut range_counts = range_counts.into_iter();
 940            for excerpt_ranges in excerpt_ranges.chunks(100) {
 941                let excerpt_ids = match this.update(&mut cx, |this, cx| {
 942                    this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
 943                }) {
 944                    Ok(excerpt_ids) => excerpt_ids,
 945                    Err(_) => return,
 946                };
 947
 948                for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.by_ref())
 949                {
 950                    for range in ranges.by_ref().take(range_count) {
 951                        let start = Anchor {
 952                            buffer_id: Some(buffer_id),
 953                            excerpt_id: excerpt_id,
 954                            text_anchor: range.start,
 955                        };
 956                        let end = Anchor {
 957                            buffer_id: Some(buffer_id),
 958                            excerpt_id: excerpt_id,
 959                            text_anchor: range.end,
 960                        };
 961                        if tx.send(start..end).await.is_err() {
 962                            break;
 963                        }
 964                    }
 965                }
 966            }
 967        })
 968        .detach();
 969
 970        rx
 971    }
 972
 973    pub fn push_excerpts<O>(
 974        &mut self,
 975        buffer: Model<Buffer>,
 976        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
 977        cx: &mut ModelContext<Self>,
 978    ) -> Vec<ExcerptId>
 979    where
 980        O: text::ToOffset,
 981    {
 982        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
 983    }
 984
 985    pub fn push_excerpts_with_context_lines<O>(
 986        &mut self,
 987        buffer: Model<Buffer>,
 988        ranges: Vec<Range<O>>,
 989        context_line_count: u32,
 990        cx: &mut ModelContext<Self>,
 991    ) -> Vec<Range<Anchor>>
 992    where
 993        O: text::ToPoint + text::ToOffset,
 994    {
 995        let buffer_id = buffer.read(cx).remote_id();
 996        let buffer_snapshot = buffer.read(cx).snapshot();
 997        let (excerpt_ranges, range_counts) =
 998            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 999
1000        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
1001
1002        let mut anchor_ranges = Vec::new();
1003        let mut ranges = ranges.into_iter();
1004        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
1005            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
1006                let start = Anchor {
1007                    buffer_id: Some(buffer_id),
1008                    excerpt_id: excerpt_id,
1009                    text_anchor: buffer_snapshot.anchor_after(range.start),
1010                };
1011                let end = Anchor {
1012                    buffer_id: Some(buffer_id),
1013                    excerpt_id: excerpt_id,
1014                    text_anchor: buffer_snapshot.anchor_after(range.end),
1015                };
1016                start..end
1017            }))
1018        }
1019        anchor_ranges
1020    }
1021
1022    pub fn insert_excerpts_after<O>(
1023        &mut self,
1024        prev_excerpt_id: ExcerptId,
1025        buffer: Model<Buffer>,
1026        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1027        cx: &mut ModelContext<Self>,
1028    ) -> Vec<ExcerptId>
1029    where
1030        O: text::ToOffset,
1031    {
1032        let mut ids = Vec::new();
1033        let mut next_excerpt_id =
1034            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1035                last_entry.id.0 + 1
1036            } else {
1037                1
1038            };
1039        self.insert_excerpts_with_ids_after(
1040            prev_excerpt_id,
1041            buffer,
1042            ranges.into_iter().map(|range| {
1043                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1044                ids.push(id);
1045                (id, range)
1046            }),
1047            cx,
1048        );
1049        ids
1050    }
1051
1052    pub fn insert_excerpts_with_ids_after<O>(
1053        &mut self,
1054        prev_excerpt_id: ExcerptId,
1055        buffer: Model<Buffer>,
1056        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1057        cx: &mut ModelContext<Self>,
1058    ) where
1059        O: text::ToOffset,
1060    {
1061        assert_eq!(self.history.transaction_depth, 0);
1062        let mut ranges = ranges.into_iter().peekable();
1063        if ranges.peek().is_none() {
1064            return Default::default();
1065        }
1066
1067        self.sync(cx);
1068
1069        let buffer_id = buffer.read(cx).remote_id();
1070        let buffer_snapshot = buffer.read(cx).snapshot();
1071
1072        let mut buffers = self.buffers.borrow_mut();
1073        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
1074            last_version: buffer_snapshot.version().clone(),
1075            last_parse_count: buffer_snapshot.parse_count(),
1076            last_selections_update_count: buffer_snapshot.selections_update_count(),
1077            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
1078            last_file_update_count: buffer_snapshot.file_update_count(),
1079            last_git_diff_update_count: buffer_snapshot.git_diff_update_count(),
1080            excerpts: Default::default(),
1081            _subscriptions: [
1082                cx.observe(&buffer, |_, _, cx| cx.notify()),
1083                cx.subscribe(&buffer, Self::on_buffer_event),
1084            ],
1085            buffer: buffer.clone(),
1086        });
1087
1088        let mut snapshot = self.snapshot.borrow_mut();
1089
1090        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1091        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1092        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1093        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
1094        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1095
1096        let edit_start = new_excerpts.summary().text.len;
1097        new_excerpts.update_last(
1098            |excerpt| {
1099                excerpt.has_trailing_newline = true;
1100            },
1101            &(),
1102        );
1103
1104        let next_locator = if let Some(excerpt) = cursor.item() {
1105            excerpt.locator.clone()
1106        } else {
1107            Locator::max()
1108        };
1109
1110        let mut excerpts = Vec::new();
1111        while let Some((id, range)) = ranges.next() {
1112            let locator = Locator::between(&prev_locator, &next_locator);
1113            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1114                buffer_state.excerpts.insert(ix, locator.clone());
1115            }
1116            let range = ExcerptRange {
1117                context: buffer_snapshot.anchor_before(&range.context.start)
1118                    ..buffer_snapshot.anchor_after(&range.context.end),
1119                primary: range.primary.map(|primary| {
1120                    buffer_snapshot.anchor_before(&primary.start)
1121                        ..buffer_snapshot.anchor_after(&primary.end)
1122                }),
1123            };
1124            excerpts.push((id, range.clone()));
1125            let excerpt = Excerpt::new(
1126                id,
1127                locator.clone(),
1128                buffer_id,
1129                buffer_snapshot.clone(),
1130                range,
1131                ranges.peek().is_some() || cursor.item().is_some(),
1132            );
1133            new_excerpts.push(excerpt, &());
1134            prev_locator = locator.clone();
1135
1136            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1137                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1138            }
1139            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
1140        }
1141
1142        let edit_end = new_excerpts.summary().text.len;
1143
1144        let suffix = cursor.suffix(&());
1145        let changed_trailing_excerpt = suffix.is_empty();
1146        new_excerpts.append(suffix, &());
1147        drop(cursor);
1148        snapshot.excerpts = new_excerpts;
1149        snapshot.excerpt_ids = new_excerpt_ids;
1150        if changed_trailing_excerpt {
1151            snapshot.trailing_excerpt_update_count += 1;
1152        }
1153
1154        self.subscriptions.publish_mut([Edit {
1155            old: edit_start..edit_start,
1156            new: edit_start..edit_end,
1157        }]);
1158        cx.emit(Event::Edited {
1159            singleton_buffer_edited: false,
1160        });
1161        cx.emit(Event::ExcerptsAdded {
1162            buffer,
1163            predecessor: prev_excerpt_id,
1164            excerpts,
1165        });
1166        cx.notify();
1167    }
1168
1169    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1170        self.sync(cx);
1171        let ids = self.excerpt_ids();
1172        self.buffers.borrow_mut().clear();
1173        let mut snapshot = self.snapshot.borrow_mut();
1174        let prev_len = snapshot.len();
1175        snapshot.excerpts = Default::default();
1176        snapshot.trailing_excerpt_update_count += 1;
1177        snapshot.is_dirty = false;
1178        snapshot.has_conflict = false;
1179
1180        self.subscriptions.publish_mut([Edit {
1181            old: 0..prev_len,
1182            new: 0..0,
1183        }]);
1184        cx.emit(Event::Edited {
1185            singleton_buffer_edited: false,
1186        });
1187        cx.emit(Event::ExcerptsRemoved { ids });
1188        cx.notify();
1189    }
1190
1191    pub fn excerpts_for_buffer(
1192        &self,
1193        buffer: &Model<Buffer>,
1194        cx: &AppContext,
1195    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1196        let mut excerpts = Vec::new();
1197        let snapshot = self.read(cx);
1198        let buffers = self.buffers.borrow();
1199        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1200        for locator in buffers
1201            .get(&buffer.read(cx).remote_id())
1202            .map(|state| &state.excerpts)
1203            .into_iter()
1204            .flatten()
1205        {
1206            cursor.seek_forward(&Some(locator), Bias::Left, &());
1207            if let Some(excerpt) = cursor.item() {
1208                if excerpt.locator == *locator {
1209                    excerpts.push((excerpt.id, excerpt.range.clone()));
1210                }
1211            }
1212        }
1213
1214        excerpts
1215    }
1216
1217    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1218        self.snapshot
1219            .borrow()
1220            .excerpts
1221            .iter()
1222            .map(|entry| entry.id)
1223            .collect()
1224    }
1225
1226    pub fn excerpt_containing(
1227        &self,
1228        position: impl ToOffset,
1229        cx: &AppContext,
1230    ) -> Option<(ExcerptId, Model<Buffer>, Range<text::Anchor>)> {
1231        let snapshot = self.read(cx);
1232        let position = position.to_offset(&snapshot);
1233
1234        let mut cursor = snapshot.excerpts.cursor::<usize>();
1235        cursor.seek(&position, Bias::Right, &());
1236        cursor
1237            .item()
1238            .or_else(|| snapshot.excerpts.last())
1239            .map(|excerpt| {
1240                (
1241                    excerpt.id,
1242                    self.buffers
1243                        .borrow()
1244                        .get(&excerpt.buffer_id)
1245                        .unwrap()
1246                        .buffer
1247                        .clone(),
1248                    excerpt.range.context.clone(),
1249                )
1250            })
1251    }
1252
1253    // If point is at the end of the buffer, the last excerpt is returned
1254    pub fn point_to_buffer_offset<T: ToOffset>(
1255        &self,
1256        point: T,
1257        cx: &AppContext,
1258    ) -> Option<(Model<Buffer>, usize, ExcerptId)> {
1259        let snapshot = self.read(cx);
1260        let offset = point.to_offset(&snapshot);
1261        let mut cursor = snapshot.excerpts.cursor::<usize>();
1262        cursor.seek(&offset, Bias::Right, &());
1263        if cursor.item().is_none() {
1264            cursor.prev(&());
1265        }
1266
1267        cursor.item().map(|excerpt| {
1268            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1269            let buffer_point = excerpt_start + offset - *cursor.start();
1270            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1271
1272            (buffer, buffer_point, excerpt.id)
1273        })
1274    }
1275
1276    pub fn range_to_buffer_ranges<T: ToOffset>(
1277        &self,
1278        range: Range<T>,
1279        cx: &AppContext,
1280    ) -> Vec<(Model<Buffer>, Range<usize>, ExcerptId)> {
1281        let snapshot = self.read(cx);
1282        let start = range.start.to_offset(&snapshot);
1283        let end = range.end.to_offset(&snapshot);
1284
1285        let mut result = Vec::new();
1286        let mut cursor = snapshot.excerpts.cursor::<usize>();
1287        cursor.seek(&start, Bias::Right, &());
1288        if cursor.item().is_none() {
1289            cursor.prev(&());
1290        }
1291
1292        while let Some(excerpt) = cursor.item() {
1293            if *cursor.start() > end {
1294                break;
1295            }
1296
1297            let mut end_before_newline = cursor.end(&());
1298            if excerpt.has_trailing_newline {
1299                end_before_newline -= 1;
1300            }
1301            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1302            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1303            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1304            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1305            result.push((buffer, start..end, excerpt.id));
1306            cursor.next(&());
1307        }
1308
1309        result
1310    }
1311
1312    pub fn remove_excerpts(
1313        &mut self,
1314        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1315        cx: &mut ModelContext<Self>,
1316    ) {
1317        self.sync(cx);
1318        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1319        if ids.is_empty() {
1320            return;
1321        }
1322
1323        let mut buffers = self.buffers.borrow_mut();
1324        let mut snapshot = self.snapshot.borrow_mut();
1325        let mut new_excerpts = SumTree::new();
1326        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1327        let mut edits = Vec::new();
1328        let mut excerpt_ids = ids.iter().copied().peekable();
1329
1330        while let Some(excerpt_id) = excerpt_ids.next() {
1331            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1332            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1333            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1334
1335            if let Some(mut excerpt) = cursor.item() {
1336                if excerpt.id != excerpt_id {
1337                    continue;
1338                }
1339                let mut old_start = cursor.start().1;
1340
1341                // Skip over the removed excerpt.
1342                'remove_excerpts: loop {
1343                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1344                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1345                        if buffer_state.excerpts.is_empty() {
1346                            buffers.remove(&excerpt.buffer_id);
1347                        }
1348                    }
1349                    cursor.next(&());
1350
1351                    // Skip over any subsequent excerpts that are also removed.
1352                    while let Some(&next_excerpt_id) = excerpt_ids.peek() {
1353                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1354                        if let Some(next_excerpt) = cursor.item() {
1355                            if next_excerpt.locator == *next_locator {
1356                                excerpt_ids.next();
1357                                excerpt = next_excerpt;
1358                                continue 'remove_excerpts;
1359                            }
1360                        }
1361                        break;
1362                    }
1363
1364                    break;
1365                }
1366
1367                // When removing the last excerpt, remove the trailing newline from
1368                // the previous excerpt.
1369                if cursor.item().is_none() && old_start > 0 {
1370                    old_start -= 1;
1371                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1372                }
1373
1374                // Push an edit for the removal of this run of excerpts.
1375                let old_end = cursor.start().1;
1376                let new_start = new_excerpts.summary().text.len;
1377                edits.push(Edit {
1378                    old: old_start..old_end,
1379                    new: new_start..new_start,
1380                });
1381            }
1382        }
1383        let suffix = cursor.suffix(&());
1384        let changed_trailing_excerpt = suffix.is_empty();
1385        new_excerpts.append(suffix, &());
1386        drop(cursor);
1387        snapshot.excerpts = new_excerpts;
1388
1389        if changed_trailing_excerpt {
1390            snapshot.trailing_excerpt_update_count += 1;
1391        }
1392
1393        self.subscriptions.publish_mut(edits);
1394        cx.emit(Event::Edited {
1395            singleton_buffer_edited: false,
1396        });
1397        cx.emit(Event::ExcerptsRemoved { ids });
1398        cx.notify();
1399    }
1400
1401    pub fn wait_for_anchors<'a>(
1402        &self,
1403        anchors: impl 'a + Iterator<Item = Anchor>,
1404        cx: &mut ModelContext<Self>,
1405    ) -> impl 'static + Future<Output = Result<()>> {
1406        let borrow = self.buffers.borrow();
1407        let mut error = None;
1408        let mut futures = Vec::new();
1409        for anchor in anchors {
1410            if let Some(buffer_id) = anchor.buffer_id {
1411                if let Some(buffer) = borrow.get(&buffer_id) {
1412                    buffer.buffer.update(cx, |buffer, _| {
1413                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1414                    });
1415                } else {
1416                    error = Some(anyhow!(
1417                        "buffer {buffer_id} is not part of this multi-buffer"
1418                    ));
1419                    break;
1420                }
1421            }
1422        }
1423        async move {
1424            if let Some(error) = error {
1425                Err(error)?;
1426            }
1427            for future in futures {
1428                future.await?;
1429            }
1430            Ok(())
1431        }
1432    }
1433
1434    pub fn text_anchor_for_position<T: ToOffset>(
1435        &self,
1436        position: T,
1437        cx: &AppContext,
1438    ) -> Option<(Model<Buffer>, language::Anchor)> {
1439        let snapshot = self.read(cx);
1440        let anchor = snapshot.anchor_before(position);
1441        let buffer = self
1442            .buffers
1443            .borrow()
1444            .get(&anchor.buffer_id?)?
1445            .buffer
1446            .clone();
1447        Some((buffer, anchor.text_anchor))
1448    }
1449
1450    fn on_buffer_event(
1451        &mut self,
1452        buffer: Model<Buffer>,
1453        event: &language::Event,
1454        cx: &mut ModelContext<Self>,
1455    ) {
1456        cx.emit(match event {
1457            language::Event::Edited => Event::Edited {
1458                singleton_buffer_edited: true,
1459            },
1460            language::Event::DirtyChanged => Event::DirtyChanged,
1461            language::Event::Saved => Event::Saved,
1462            language::Event::FileHandleChanged => Event::FileHandleChanged,
1463            language::Event::Reloaded => Event::Reloaded,
1464            language::Event::DiffBaseChanged => Event::DiffBaseChanged,
1465            language::Event::LanguageChanged => Event::LanguageChanged,
1466            language::Event::Reparsed => Event::Reparsed,
1467            language::Event::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1468            language::Event::Closed => Event::Closed,
1469            language::Event::CapabilityChanged => {
1470                self.capability = buffer.read(cx).capability();
1471                Event::CapabilityChanged
1472            }
1473
1474            //
1475            language::Event::Operation(_) => return,
1476        });
1477    }
1478
1479    pub fn all_buffers(&self) -> HashSet<Model<Buffer>> {
1480        self.buffers
1481            .borrow()
1482            .values()
1483            .map(|state| state.buffer.clone())
1484            .collect()
1485    }
1486
1487    pub fn buffer(&self, buffer_id: BufferId) -> Option<Model<Buffer>> {
1488        self.buffers
1489            .borrow()
1490            .get(&buffer_id)
1491            .map(|state| state.buffer.clone())
1492    }
1493
1494    pub fn is_completion_trigger(&self, position: Anchor, text: &str, cx: &AppContext) -> bool {
1495        let mut chars = text.chars();
1496        let char = if let Some(char) = chars.next() {
1497            char
1498        } else {
1499            return false;
1500        };
1501        if chars.next().is_some() {
1502            return false;
1503        }
1504
1505        let snapshot = self.snapshot(cx);
1506        let position = position.to_offset(&snapshot);
1507        let scope = snapshot.language_scope_at(position);
1508        if char_kind(&scope, char) == CharKind::Word {
1509            return true;
1510        }
1511
1512        let anchor = snapshot.anchor_before(position);
1513        anchor
1514            .buffer_id
1515            .and_then(|buffer_id| {
1516                let buffer = self.buffers.borrow().get(&buffer_id)?.buffer.clone();
1517                Some(
1518                    buffer
1519                        .read(cx)
1520                        .completion_triggers()
1521                        .iter()
1522                        .any(|string| string == text),
1523                )
1524            })
1525            .unwrap_or(false)
1526    }
1527
1528    pub fn language_at<T: ToOffset>(&self, point: T, cx: &AppContext) -> Option<Arc<Language>> {
1529        self.point_to_buffer_offset(point, cx)
1530            .and_then(|(buffer, offset, _)| buffer.read(cx).language_at(offset))
1531    }
1532
1533    pub fn settings_at<'a, T: ToOffset>(
1534        &self,
1535        point: T,
1536        cx: &'a AppContext,
1537    ) -> &'a LanguageSettings {
1538        let mut language = None;
1539        let mut file = None;
1540        if let Some((buffer, offset, _)) = self.point_to_buffer_offset(point, cx) {
1541            let buffer = buffer.read(cx);
1542            language = buffer.language_at(offset);
1543            file = buffer.file();
1544        }
1545        language_settings(language.as_ref(), file, cx)
1546    }
1547
1548    pub fn for_each_buffer(&self, mut f: impl FnMut(&Model<Buffer>)) {
1549        self.buffers
1550            .borrow()
1551            .values()
1552            .for_each(|state| f(&state.buffer))
1553    }
1554
1555    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1556        if let Some(title) = self.title.as_ref() {
1557            return title.into();
1558        }
1559
1560        if let Some(buffer) = self.as_singleton() {
1561            if let Some(file) = buffer.read(cx).file() {
1562                return file.file_name(cx).to_string_lossy();
1563            }
1564        }
1565
1566        "untitled".into()
1567    }
1568
1569    #[cfg(any(test, feature = "test-support"))]
1570    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1571        self.as_singleton().unwrap().read(cx).is_parsing()
1572    }
1573
1574    fn sync(&self, cx: &AppContext) {
1575        let mut snapshot = self.snapshot.borrow_mut();
1576        let mut excerpts_to_edit = Vec::new();
1577        let mut reparsed = false;
1578        let mut diagnostics_updated = false;
1579        let mut git_diff_updated = false;
1580        let mut is_dirty = false;
1581        let mut has_conflict = false;
1582        let mut edited = false;
1583        let mut buffers = self.buffers.borrow_mut();
1584        for buffer_state in buffers.values_mut() {
1585            let buffer = buffer_state.buffer.read(cx);
1586            let version = buffer.version();
1587            let parse_count = buffer.parse_count();
1588            let selections_update_count = buffer.selections_update_count();
1589            let diagnostics_update_count = buffer.diagnostics_update_count();
1590            let file_update_count = buffer.file_update_count();
1591            let git_diff_update_count = buffer.git_diff_update_count();
1592
1593            let buffer_edited = version.changed_since(&buffer_state.last_version);
1594            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1595            let buffer_selections_updated =
1596                selections_update_count > buffer_state.last_selections_update_count;
1597            let buffer_diagnostics_updated =
1598                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1599            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1600            let buffer_git_diff_updated =
1601                git_diff_update_count > buffer_state.last_git_diff_update_count;
1602            if buffer_edited
1603                || buffer_reparsed
1604                || buffer_selections_updated
1605                || buffer_diagnostics_updated
1606                || buffer_file_updated
1607                || buffer_git_diff_updated
1608            {
1609                buffer_state.last_version = version;
1610                buffer_state.last_parse_count = parse_count;
1611                buffer_state.last_selections_update_count = selections_update_count;
1612                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1613                buffer_state.last_file_update_count = file_update_count;
1614                buffer_state.last_git_diff_update_count = git_diff_update_count;
1615                excerpts_to_edit.extend(
1616                    buffer_state
1617                        .excerpts
1618                        .iter()
1619                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
1620                );
1621            }
1622
1623            edited |= buffer_edited;
1624            reparsed |= buffer_reparsed;
1625            diagnostics_updated |= buffer_diagnostics_updated;
1626            git_diff_updated |= buffer_git_diff_updated;
1627            is_dirty |= buffer.is_dirty();
1628            has_conflict |= buffer.has_conflict();
1629        }
1630        if edited {
1631            snapshot.edit_count += 1;
1632        }
1633        if reparsed {
1634            snapshot.parse_count += 1;
1635        }
1636        if diagnostics_updated {
1637            snapshot.diagnostics_update_count += 1;
1638        }
1639        if git_diff_updated {
1640            snapshot.git_diff_update_count += 1;
1641        }
1642        snapshot.is_dirty = is_dirty;
1643        snapshot.has_conflict = has_conflict;
1644
1645        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
1646
1647        let mut edits = Vec::new();
1648        let mut new_excerpts = SumTree::new();
1649        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1650
1651        for (locator, buffer, buffer_edited) in excerpts_to_edit {
1652            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1653            let old_excerpt = cursor.item().unwrap();
1654            let buffer = buffer.read(cx);
1655            let buffer_id = buffer.remote_id();
1656
1657            let mut new_excerpt;
1658            if buffer_edited {
1659                edits.extend(
1660                    buffer
1661                        .edits_since_in_range::<usize>(
1662                            old_excerpt.buffer.version(),
1663                            old_excerpt.range.context.clone(),
1664                        )
1665                        .map(|mut edit| {
1666                            let excerpt_old_start = cursor.start().1;
1667                            let excerpt_new_start = new_excerpts.summary().text.len;
1668                            edit.old.start += excerpt_old_start;
1669                            edit.old.end += excerpt_old_start;
1670                            edit.new.start += excerpt_new_start;
1671                            edit.new.end += excerpt_new_start;
1672                            edit
1673                        }),
1674                );
1675
1676                new_excerpt = Excerpt::new(
1677                    old_excerpt.id,
1678                    locator.clone(),
1679                    buffer_id,
1680                    buffer.snapshot(),
1681                    old_excerpt.range.clone(),
1682                    old_excerpt.has_trailing_newline,
1683                );
1684            } else {
1685                new_excerpt = old_excerpt.clone();
1686                new_excerpt.buffer = buffer.snapshot();
1687            }
1688
1689            new_excerpts.push(new_excerpt, &());
1690            cursor.next(&());
1691        }
1692        new_excerpts.append(cursor.suffix(&()), &());
1693
1694        drop(cursor);
1695        snapshot.excerpts = new_excerpts;
1696
1697        self.subscriptions.publish(edits);
1698    }
1699}
1700
1701#[cfg(any(test, feature = "test-support"))]
1702impl MultiBuffer {
1703    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> Model<Self> {
1704        let buffer = cx
1705            .new_model(|cx| Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text));
1706        cx.new_model(|cx| Self::singleton(buffer, cx))
1707    }
1708
1709    pub fn build_multi<const COUNT: usize>(
1710        excerpts: [(&str, Vec<Range<Point>>); COUNT],
1711        cx: &mut gpui::AppContext,
1712    ) -> Model<Self> {
1713        let multi = cx.new_model(|_| Self::new(0, Capability::ReadWrite));
1714        for (text, ranges) in excerpts {
1715            let buffer = cx.new_model(|cx| {
1716                Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text)
1717            });
1718            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
1719                context: range,
1720                primary: None,
1721            });
1722            multi.update(cx, |multi, cx| {
1723                multi.push_excerpts(buffer, excerpt_ranges, cx)
1724            });
1725        }
1726
1727        multi
1728    }
1729
1730    pub fn build_from_buffer(buffer: Model<Buffer>, cx: &mut gpui::AppContext) -> Model<Self> {
1731        cx.new_model(|cx| Self::singleton(buffer, cx))
1732    }
1733
1734    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> Model<Self> {
1735        cx.new_model(|cx| {
1736            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
1737            let mutation_count = rng.gen_range(1..=5);
1738            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
1739            multibuffer
1740        })
1741    }
1742
1743    pub fn randomly_edit(
1744        &mut self,
1745        rng: &mut impl rand::Rng,
1746        edit_count: usize,
1747        cx: &mut ModelContext<Self>,
1748    ) {
1749        use util::RandomCharIter;
1750
1751        let snapshot = self.read(cx);
1752        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1753        let mut last_end = None;
1754        for _ in 0..edit_count {
1755            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
1756                break;
1757            }
1758
1759            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1760            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
1761            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
1762            last_end = Some(end);
1763
1764            let mut range = start..end;
1765            if rng.gen_bool(0.2) {
1766                mem::swap(&mut range.start, &mut range.end);
1767            }
1768
1769            let new_text_len = rng.gen_range(0..10);
1770            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1771
1772            edits.push((range, new_text.into()));
1773        }
1774        log::info!("mutating multi-buffer with {:?}", edits);
1775        drop(snapshot);
1776
1777        self.edit(edits, None, cx);
1778    }
1779
1780    pub fn randomly_edit_excerpts(
1781        &mut self,
1782        rng: &mut impl rand::Rng,
1783        mutation_count: usize,
1784        cx: &mut ModelContext<Self>,
1785    ) {
1786        use rand::prelude::*;
1787        use std::env;
1788        use util::RandomCharIter;
1789
1790        let max_excerpts = env::var("MAX_EXCERPTS")
1791            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1792            .unwrap_or(5);
1793
1794        let mut buffers = Vec::new();
1795        for _ in 0..mutation_count {
1796            if rng.gen_bool(0.05) {
1797                log::info!("Clearing multi-buffer");
1798                self.clear(cx);
1799                continue;
1800            }
1801
1802            let excerpt_ids = self.excerpt_ids();
1803            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1804                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1805                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1806                    buffers.push(cx.new_model(|cx| {
1807                        Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text)
1808                    }));
1809                    let buffer = buffers.last().unwrap().read(cx);
1810                    log::info!(
1811                        "Creating new buffer {} with text: {:?}",
1812                        buffer.remote_id(),
1813                        buffer.text()
1814                    );
1815                    buffers.last().unwrap().clone()
1816                } else {
1817                    self.buffers
1818                        .borrow()
1819                        .values()
1820                        .choose(rng)
1821                        .unwrap()
1822                        .buffer
1823                        .clone()
1824                };
1825
1826                let buffer = buffer_handle.read(cx);
1827                let buffer_text = buffer.text();
1828                let ranges = (0..rng.gen_range(0..5))
1829                    .map(|_| {
1830                        let end_ix =
1831                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1832                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1833                        ExcerptRange {
1834                            context: start_ix..end_ix,
1835                            primary: None,
1836                        }
1837                    })
1838                    .collect::<Vec<_>>();
1839                log::info!(
1840                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
1841                    buffer_handle.read(cx).remote_id(),
1842                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
1843                    ranges
1844                        .iter()
1845                        .map(|r| &buffer_text[r.context.clone()])
1846                        .collect::<Vec<_>>()
1847                );
1848
1849                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
1850                log::info!("Inserted with ids: {:?}", excerpt_id);
1851            } else {
1852                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1853                let mut excerpts_to_remove = excerpt_ids
1854                    .choose_multiple(rng, remove_count)
1855                    .cloned()
1856                    .collect::<Vec<_>>();
1857                let snapshot = self.snapshot.borrow();
1858                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
1859                drop(snapshot);
1860                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1861                self.remove_excerpts(excerpts_to_remove, cx);
1862            }
1863        }
1864    }
1865
1866    pub fn randomly_mutate(
1867        &mut self,
1868        rng: &mut impl rand::Rng,
1869        mutation_count: usize,
1870        cx: &mut ModelContext<Self>,
1871    ) {
1872        use rand::prelude::*;
1873
1874        if rng.gen_bool(0.7) || self.singleton {
1875            let buffer = self
1876                .buffers
1877                .borrow()
1878                .values()
1879                .choose(rng)
1880                .map(|state| state.buffer.clone());
1881
1882            if let Some(buffer) = buffer {
1883                buffer.update(cx, |buffer, cx| {
1884                    if rng.gen() {
1885                        buffer.randomly_edit(rng, mutation_count, cx);
1886                    } else {
1887                        buffer.randomly_undo_redo(rng, cx);
1888                    }
1889                });
1890            } else {
1891                self.randomly_edit(rng, mutation_count, cx);
1892            }
1893        } else {
1894            self.randomly_edit_excerpts(rng, mutation_count, cx);
1895        }
1896
1897        self.check_invariants(cx);
1898    }
1899
1900    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
1901        let snapshot = self.read(cx);
1902        let excerpts = snapshot.excerpts.items(&());
1903        let excerpt_ids = snapshot.excerpt_ids.items(&());
1904
1905        for (ix, excerpt) in excerpts.iter().enumerate() {
1906            if ix == 0 {
1907                if excerpt.locator <= Locator::min() {
1908                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
1909                }
1910            } else {
1911                if excerpt.locator <= excerpts[ix - 1].locator {
1912                    panic!("excerpts are out-of-order: {:?}", excerpts);
1913                }
1914            }
1915        }
1916
1917        for (ix, entry) in excerpt_ids.iter().enumerate() {
1918            if ix == 0 {
1919                if entry.id.cmp(&ExcerptId::min(), &snapshot).is_le() {
1920                    panic!("invalid first excerpt id {:?}", entry.id);
1921                }
1922            } else {
1923                if entry.id <= excerpt_ids[ix - 1].id {
1924                    panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
1925                }
1926            }
1927        }
1928    }
1929}
1930
1931impl EventEmitter<Event> for MultiBuffer {}
1932
1933impl MultiBufferSnapshot {
1934    pub fn text(&self) -> String {
1935        self.chunks(0..self.len(), false)
1936            .map(|chunk| chunk.text)
1937            .collect()
1938    }
1939
1940    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1941        let mut offset = position.to_offset(self);
1942        let mut cursor = self.excerpts.cursor::<usize>();
1943        cursor.seek(&offset, Bias::Left, &());
1944        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1945            let end_before_footer = cursor.start() + excerpt.text_summary.len;
1946            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1947            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1948            excerpt.buffer.reversed_chunks_in_range(start..end)
1949        });
1950        iter::from_fn(move || {
1951            if offset == *cursor.start() {
1952                cursor.prev(&());
1953                let excerpt = cursor.item()?;
1954                excerpt_chunks = Some(
1955                    excerpt
1956                        .buffer
1957                        .reversed_chunks_in_range(excerpt.range.context.clone()),
1958                );
1959            }
1960
1961            let excerpt = cursor.item().unwrap();
1962            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1963                offset -= 1;
1964                Some("\n")
1965            } else {
1966                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1967                offset -= chunk.len();
1968                Some(chunk)
1969            }
1970        })
1971        .flat_map(|c| c.chars().rev())
1972    }
1973
1974    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
1975        let offset = position.to_offset(self);
1976        self.text_for_range(offset..self.len())
1977            .flat_map(|chunk| chunk.chars())
1978    }
1979
1980    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
1981        self.chunks(range, false).map(|chunk| chunk.text)
1982    }
1983
1984    pub fn is_line_blank(&self, row: u32) -> bool {
1985        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1986            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1987    }
1988
1989    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1990    where
1991        T: ToOffset,
1992    {
1993        let position = position.to_offset(self);
1994        position == self.clip_offset(position, Bias::Left)
1995            && self
1996                .bytes_in_range(position..self.len())
1997                .flatten()
1998                .copied()
1999                .take(needle.len())
2000                .eq(needle.bytes())
2001    }
2002
2003    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
2004        let mut start = start.to_offset(self);
2005        let mut end = start;
2006        let mut next_chars = self.chars_at(start).peekable();
2007        let mut prev_chars = self.reversed_chars_at(start).peekable();
2008
2009        let scope = self.language_scope_at(start);
2010        let kind = |c| char_kind(&scope, c);
2011        let word_kind = cmp::max(
2012            prev_chars.peek().copied().map(kind),
2013            next_chars.peek().copied().map(kind),
2014        );
2015
2016        for ch in prev_chars {
2017            if Some(kind(ch)) == word_kind && ch != '\n' {
2018                start -= ch.len_utf8();
2019            } else {
2020                break;
2021            }
2022        }
2023
2024        for ch in next_chars {
2025            if Some(kind(ch)) == word_kind && ch != '\n' {
2026                end += ch.len_utf8();
2027            } else {
2028                break;
2029            }
2030        }
2031
2032        (start..end, word_kind)
2033    }
2034
2035    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
2036        if self.singleton {
2037            self.excerpts
2038                .iter()
2039                .next()
2040                .map(|e| (&e.id, e.buffer_id, &e.buffer))
2041        } else {
2042            None
2043        }
2044    }
2045
2046    pub fn len(&self) -> usize {
2047        self.excerpts.summary().text.len
2048    }
2049
2050    pub fn is_empty(&self) -> bool {
2051        self.excerpts.summary().text.len == 0
2052    }
2053
2054    pub fn max_buffer_row(&self) -> u32 {
2055        self.excerpts.summary().max_buffer_row
2056    }
2057
2058    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2059        if let Some((_, _, buffer)) = self.as_singleton() {
2060            return buffer.clip_offset(offset, bias);
2061        }
2062
2063        let mut cursor = self.excerpts.cursor::<usize>();
2064        cursor.seek(&offset, Bias::Right, &());
2065        let overshoot = if let Some(excerpt) = cursor.item() {
2066            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2067            let buffer_offset = excerpt
2068                .buffer
2069                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
2070            buffer_offset.saturating_sub(excerpt_start)
2071        } else {
2072            0
2073        };
2074        cursor.start() + overshoot
2075    }
2076
2077    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2078        if let Some((_, _, buffer)) = self.as_singleton() {
2079            return buffer.clip_point(point, bias);
2080        }
2081
2082        let mut cursor = self.excerpts.cursor::<Point>();
2083        cursor.seek(&point, Bias::Right, &());
2084        let overshoot = if let Some(excerpt) = cursor.item() {
2085            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2086            let buffer_point = excerpt
2087                .buffer
2088                .clip_point(excerpt_start + (point - cursor.start()), bias);
2089            buffer_point.saturating_sub(excerpt_start)
2090        } else {
2091            Point::zero()
2092        };
2093        *cursor.start() + overshoot
2094    }
2095
2096    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2097        if let Some((_, _, buffer)) = self.as_singleton() {
2098            return buffer.clip_offset_utf16(offset, bias);
2099        }
2100
2101        let mut cursor = self.excerpts.cursor::<OffsetUtf16>();
2102        cursor.seek(&offset, Bias::Right, &());
2103        let overshoot = if let Some(excerpt) = cursor.item() {
2104            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2105            let buffer_offset = excerpt
2106                .buffer
2107                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
2108            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
2109        } else {
2110            OffsetUtf16(0)
2111        };
2112        *cursor.start() + overshoot
2113    }
2114
2115    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2116        if let Some((_, _, buffer)) = self.as_singleton() {
2117            return buffer.clip_point_utf16(point, bias);
2118        }
2119
2120        let mut cursor = self.excerpts.cursor::<PointUtf16>();
2121        cursor.seek(&point.0, Bias::Right, &());
2122        let overshoot = if let Some(excerpt) = cursor.item() {
2123            let excerpt_start = excerpt
2124                .buffer
2125                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2126            let buffer_point = excerpt
2127                .buffer
2128                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
2129            buffer_point.saturating_sub(excerpt_start)
2130        } else {
2131            PointUtf16::zero()
2132        };
2133        *cursor.start() + overshoot
2134    }
2135
2136    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
2137        let range = range.start.to_offset(self)..range.end.to_offset(self);
2138        let mut excerpts = self.excerpts.cursor::<usize>();
2139        excerpts.seek(&range.start, Bias::Right, &());
2140
2141        let mut chunk = &[][..];
2142        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2143            let mut excerpt_bytes = excerpt
2144                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
2145            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2146            Some(excerpt_bytes)
2147        } else {
2148            None
2149        };
2150        MultiBufferBytes {
2151            range,
2152            excerpts,
2153            excerpt_bytes,
2154            chunk,
2155        }
2156    }
2157
2158    pub fn reversed_bytes_in_range<T: ToOffset>(
2159        &self,
2160        range: Range<T>,
2161    ) -> ReversedMultiBufferBytes {
2162        let range = range.start.to_offset(self)..range.end.to_offset(self);
2163        let mut excerpts = self.excerpts.cursor::<usize>();
2164        excerpts.seek(&range.end, Bias::Left, &());
2165
2166        let mut chunk = &[][..];
2167        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2168            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
2169                range.start - excerpts.start()..range.end - excerpts.start(),
2170            );
2171            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2172            Some(excerpt_bytes)
2173        } else {
2174            None
2175        };
2176
2177        ReversedMultiBufferBytes {
2178            range,
2179            excerpts,
2180            excerpt_bytes,
2181            chunk,
2182        }
2183    }
2184
2185    pub fn buffer_rows(&self, start_row: u32) -> MultiBufferRows {
2186        let mut result = MultiBufferRows {
2187            buffer_row_range: 0..0,
2188            excerpts: self.excerpts.cursor(),
2189        };
2190        result.seek(start_row);
2191        result
2192    }
2193
2194    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
2195        let range = range.start.to_offset(self)..range.end.to_offset(self);
2196        let mut chunks = MultiBufferChunks {
2197            range: range.clone(),
2198            excerpts: self.excerpts.cursor(),
2199            excerpt_chunks: None,
2200            language_aware,
2201        };
2202        chunks.seek(range.start);
2203        chunks
2204    }
2205
2206    pub fn offset_to_point(&self, offset: usize) -> Point {
2207        if let Some((_, _, buffer)) = self.as_singleton() {
2208            return buffer.offset_to_point(offset);
2209        }
2210
2211        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2212        cursor.seek(&offset, Bias::Right, &());
2213        if let Some(excerpt) = cursor.item() {
2214            let (start_offset, start_point) = cursor.start();
2215            let overshoot = offset - start_offset;
2216            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2217            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2218            let buffer_point = excerpt
2219                .buffer
2220                .offset_to_point(excerpt_start_offset + overshoot);
2221            *start_point + (buffer_point - excerpt_start_point)
2222        } else {
2223            self.excerpts.summary().text.lines
2224        }
2225    }
2226
2227    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2228        if let Some((_, _, buffer)) = self.as_singleton() {
2229            return buffer.offset_to_point_utf16(offset);
2230        }
2231
2232        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
2233        cursor.seek(&offset, Bias::Right, &());
2234        if let Some(excerpt) = cursor.item() {
2235            let (start_offset, start_point) = cursor.start();
2236            let overshoot = offset - start_offset;
2237            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2238            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2239            let buffer_point = excerpt
2240                .buffer
2241                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2242            *start_point + (buffer_point - excerpt_start_point)
2243        } else {
2244            self.excerpts.summary().text.lines_utf16()
2245        }
2246    }
2247
2248    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2249        if let Some((_, _, buffer)) = self.as_singleton() {
2250            return buffer.point_to_point_utf16(point);
2251        }
2252
2253        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
2254        cursor.seek(&point, Bias::Right, &());
2255        if let Some(excerpt) = cursor.item() {
2256            let (start_offset, start_point) = cursor.start();
2257            let overshoot = point - start_offset;
2258            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2259            let excerpt_start_point_utf16 =
2260                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2261            let buffer_point = excerpt
2262                .buffer
2263                .point_to_point_utf16(excerpt_start_point + overshoot);
2264            *start_point + (buffer_point - excerpt_start_point_utf16)
2265        } else {
2266            self.excerpts.summary().text.lines_utf16()
2267        }
2268    }
2269
2270    pub fn point_to_offset(&self, point: Point) -> usize {
2271        if let Some((_, _, buffer)) = self.as_singleton() {
2272            return buffer.point_to_offset(point);
2273        }
2274
2275        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
2276        cursor.seek(&point, Bias::Right, &());
2277        if let Some(excerpt) = cursor.item() {
2278            let (start_point, start_offset) = cursor.start();
2279            let overshoot = point - start_point;
2280            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2281            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2282            let buffer_offset = excerpt
2283                .buffer
2284                .point_to_offset(excerpt_start_point + overshoot);
2285            *start_offset + buffer_offset - excerpt_start_offset
2286        } else {
2287            self.excerpts.summary().text.len
2288        }
2289    }
2290
2291    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2292        if let Some((_, _, buffer)) = self.as_singleton() {
2293            return buffer.offset_utf16_to_offset(offset_utf16);
2294        }
2295
2296        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>();
2297        cursor.seek(&offset_utf16, Bias::Right, &());
2298        if let Some(excerpt) = cursor.item() {
2299            let (start_offset_utf16, start_offset) = cursor.start();
2300            let overshoot = offset_utf16 - start_offset_utf16;
2301            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2302            let excerpt_start_offset_utf16 =
2303                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2304            let buffer_offset = excerpt
2305                .buffer
2306                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2307            *start_offset + (buffer_offset - excerpt_start_offset)
2308        } else {
2309            self.excerpts.summary().text.len
2310        }
2311    }
2312
2313    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2314        if let Some((_, _, buffer)) = self.as_singleton() {
2315            return buffer.offset_to_offset_utf16(offset);
2316        }
2317
2318        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>();
2319        cursor.seek(&offset, Bias::Right, &());
2320        if let Some(excerpt) = cursor.item() {
2321            let (start_offset, start_offset_utf16) = cursor.start();
2322            let overshoot = offset - start_offset;
2323            let excerpt_start_offset_utf16 =
2324                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2325            let excerpt_start_offset = excerpt
2326                .buffer
2327                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2328            let buffer_offset_utf16 = excerpt
2329                .buffer
2330                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2331            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2332        } else {
2333            self.excerpts.summary().text.len_utf16
2334        }
2335    }
2336
2337    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2338        if let Some((_, _, buffer)) = self.as_singleton() {
2339            return buffer.point_utf16_to_offset(point);
2340        }
2341
2342        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
2343        cursor.seek(&point, Bias::Right, &());
2344        if let Some(excerpt) = cursor.item() {
2345            let (start_point, start_offset) = cursor.start();
2346            let overshoot = point - start_point;
2347            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2348            let excerpt_start_point = excerpt
2349                .buffer
2350                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2351            let buffer_offset = excerpt
2352                .buffer
2353                .point_utf16_to_offset(excerpt_start_point + overshoot);
2354            *start_offset + (buffer_offset - excerpt_start_offset)
2355        } else {
2356            self.excerpts.summary().text.len
2357        }
2358    }
2359
2360    pub fn point_to_buffer_offset<T: ToOffset>(
2361        &self,
2362        point: T,
2363    ) -> Option<(&BufferSnapshot, usize)> {
2364        let offset = point.to_offset(self);
2365        let mut cursor = self.excerpts.cursor::<usize>();
2366        cursor.seek(&offset, Bias::Right, &());
2367        if cursor.item().is_none() {
2368            cursor.prev(&());
2369        }
2370
2371        cursor.item().map(|excerpt| {
2372            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2373            let buffer_point = excerpt_start + offset - *cursor.start();
2374            (&excerpt.buffer, buffer_point)
2375        })
2376    }
2377
2378    pub fn suggested_indents(
2379        &self,
2380        rows: impl IntoIterator<Item = u32>,
2381        cx: &AppContext,
2382    ) -> BTreeMap<u32, IndentSize> {
2383        let mut result = BTreeMap::new();
2384
2385        let mut rows_for_excerpt = Vec::new();
2386        let mut cursor = self.excerpts.cursor::<Point>();
2387        let mut rows = rows.into_iter().peekable();
2388        let mut prev_row = u32::MAX;
2389        let mut prev_language_indent_size = IndentSize::default();
2390
2391        while let Some(row) = rows.next() {
2392            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2393            let excerpt = match cursor.item() {
2394                Some(excerpt) => excerpt,
2395                _ => continue,
2396            };
2397
2398            // Retrieve the language and indent size once for each disjoint region being indented.
2399            let single_indent_size = if row.saturating_sub(1) == prev_row {
2400                prev_language_indent_size
2401            } else {
2402                excerpt
2403                    .buffer
2404                    .language_indent_size_at(Point::new(row, 0), cx)
2405            };
2406            prev_language_indent_size = single_indent_size;
2407            prev_row = row;
2408
2409            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2410            let start_multibuffer_row = cursor.start().row;
2411
2412            rows_for_excerpt.push(row);
2413            while let Some(next_row) = rows.peek().copied() {
2414                if cursor.end(&()).row > next_row {
2415                    rows_for_excerpt.push(next_row);
2416                    rows.next();
2417                } else {
2418                    break;
2419                }
2420            }
2421
2422            let buffer_rows = rows_for_excerpt
2423                .drain(..)
2424                .map(|row| start_buffer_row + row - start_multibuffer_row);
2425            let buffer_indents = excerpt
2426                .buffer
2427                .suggested_indents(buffer_rows, single_indent_size);
2428            let multibuffer_indents = buffer_indents
2429                .into_iter()
2430                .map(|(row, indent)| (start_multibuffer_row + row - start_buffer_row, indent));
2431            result.extend(multibuffer_indents);
2432        }
2433
2434        result
2435    }
2436
2437    pub fn indent_size_for_line(&self, row: u32) -> IndentSize {
2438        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2439            let mut size = buffer.indent_size_for_line(range.start.row);
2440            size.len = size
2441                .len
2442                .min(range.end.column)
2443                .saturating_sub(range.start.column);
2444            size
2445        } else {
2446            IndentSize::spaces(0)
2447        }
2448    }
2449
2450    pub fn prev_non_blank_row(&self, mut row: u32) -> Option<u32> {
2451        while row > 0 {
2452            row -= 1;
2453            if !self.is_line_blank(row) {
2454                return Some(row);
2455            }
2456        }
2457        None
2458    }
2459
2460    pub fn line_len(&self, row: u32) -> u32 {
2461        if let Some((_, range)) = self.buffer_line_for_row(row) {
2462            range.end.column - range.start.column
2463        } else {
2464            0
2465        }
2466    }
2467
2468    pub fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
2469        let mut cursor = self.excerpts.cursor::<Point>();
2470        let point = Point::new(row, 0);
2471        cursor.seek(&point, Bias::Right, &());
2472        if cursor.item().is_none() && *cursor.start() == point {
2473            cursor.prev(&());
2474        }
2475        if let Some(excerpt) = cursor.item() {
2476            let overshoot = row - cursor.start().row;
2477            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2478            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2479            let buffer_row = excerpt_start.row + overshoot;
2480            let line_start = Point::new(buffer_row, 0);
2481            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2482            return Some((
2483                &excerpt.buffer,
2484                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2485            ));
2486        }
2487        None
2488    }
2489
2490    pub fn max_point(&self) -> Point {
2491        self.text_summary().lines
2492    }
2493
2494    pub fn text_summary(&self) -> TextSummary {
2495        self.excerpts.summary().text.clone()
2496    }
2497
2498    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2499    where
2500        D: TextDimension,
2501        O: ToOffset,
2502    {
2503        let mut summary = D::default();
2504        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2505        let mut cursor = self.excerpts.cursor::<usize>();
2506        cursor.seek(&range.start, Bias::Right, &());
2507        if let Some(excerpt) = cursor.item() {
2508            let mut end_before_newline = cursor.end(&());
2509            if excerpt.has_trailing_newline {
2510                end_before_newline -= 1;
2511            }
2512
2513            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2514            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2515            let end_in_excerpt =
2516                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2517            summary.add_assign(
2518                &excerpt
2519                    .buffer
2520                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2521            );
2522
2523            if range.end > end_before_newline {
2524                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2525            }
2526
2527            cursor.next(&());
2528        }
2529
2530        if range.end > *cursor.start() {
2531            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2532                &range.end,
2533                Bias::Right,
2534                &(),
2535            )));
2536            if let Some(excerpt) = cursor.item() {
2537                range.end = cmp::max(*cursor.start(), range.end);
2538
2539                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2540                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2541                summary.add_assign(
2542                    &excerpt
2543                        .buffer
2544                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2545                );
2546            }
2547        }
2548
2549        summary
2550    }
2551
2552    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2553    where
2554        D: TextDimension + Ord + Sub<D, Output = D>,
2555    {
2556        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2557        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
2558
2559        cursor.seek(locator, Bias::Left, &());
2560        if cursor.item().is_none() {
2561            cursor.next(&());
2562        }
2563
2564        let mut position = D::from_text_summary(&cursor.start().text);
2565        if let Some(excerpt) = cursor.item() {
2566            if excerpt.id == anchor.excerpt_id {
2567                let excerpt_buffer_start =
2568                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2569                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2570                let buffer_position = cmp::min(
2571                    excerpt_buffer_end,
2572                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
2573                );
2574                if buffer_position > excerpt_buffer_start {
2575                    position.add_assign(&(buffer_position - excerpt_buffer_start));
2576                }
2577            }
2578        }
2579        position
2580    }
2581
2582    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
2583    where
2584        D: TextDimension + Ord + Sub<D, Output = D>,
2585        I: 'a + IntoIterator<Item = &'a Anchor>,
2586    {
2587        if let Some((_, _, buffer)) = self.as_singleton() {
2588            return buffer
2589                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
2590                .collect();
2591        }
2592
2593        let mut anchors = anchors.into_iter().peekable();
2594        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2595        let mut summaries = Vec::new();
2596        while let Some(anchor) = anchors.peek() {
2597            let excerpt_id = anchor.excerpt_id;
2598            let excerpt_anchors = iter::from_fn(|| {
2599                let anchor = anchors.peek()?;
2600                if anchor.excerpt_id == excerpt_id {
2601                    Some(&anchors.next().unwrap().text_anchor)
2602                } else {
2603                    None
2604                }
2605            });
2606
2607            let locator = self.excerpt_locator_for_id(excerpt_id);
2608            cursor.seek_forward(locator, Bias::Left, &());
2609            if cursor.item().is_none() {
2610                cursor.next(&());
2611            }
2612
2613            let position = D::from_text_summary(&cursor.start().text);
2614            if let Some(excerpt) = cursor.item() {
2615                if excerpt.id == excerpt_id {
2616                    let excerpt_buffer_start =
2617                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2618                    let excerpt_buffer_end =
2619                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2620                    summaries.extend(
2621                        excerpt
2622                            .buffer
2623                            .summaries_for_anchors::<D, _>(excerpt_anchors)
2624                            .map(move |summary| {
2625                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
2626                                let mut position = position.clone();
2627                                let excerpt_buffer_start = excerpt_buffer_start.clone();
2628                                if summary > excerpt_buffer_start {
2629                                    position.add_assign(&(summary - excerpt_buffer_start));
2630                                }
2631                                position
2632                            }),
2633                    );
2634                    continue;
2635                }
2636            }
2637
2638            summaries.extend(excerpt_anchors.map(|_| position.clone()));
2639        }
2640
2641        summaries
2642    }
2643
2644    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
2645    where
2646        I: 'a + IntoIterator<Item = &'a Anchor>,
2647    {
2648        let mut anchors = anchors.into_iter().enumerate().peekable();
2649        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2650        cursor.next(&());
2651
2652        let mut result = Vec::new();
2653
2654        while let Some((_, anchor)) = anchors.peek() {
2655            let old_excerpt_id = anchor.excerpt_id;
2656
2657            // Find the location where this anchor's excerpt should be.
2658            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
2659            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
2660
2661            if cursor.item().is_none() {
2662                cursor.next(&());
2663            }
2664
2665            let next_excerpt = cursor.item();
2666            let prev_excerpt = cursor.prev_item();
2667
2668            // Process all of the anchors for this excerpt.
2669            while let Some((_, anchor)) = anchors.peek() {
2670                if anchor.excerpt_id != old_excerpt_id {
2671                    break;
2672                }
2673                let (anchor_ix, anchor) = anchors.next().unwrap();
2674                let mut anchor = *anchor;
2675
2676                // Leave min and max anchors unchanged if invalid or
2677                // if the old excerpt still exists at this location
2678                let mut kept_position = next_excerpt
2679                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
2680                    || old_excerpt_id == ExcerptId::max()
2681                    || old_excerpt_id == ExcerptId::min();
2682
2683                // If the old excerpt no longer exists at this location, then attempt to
2684                // find an equivalent position for this anchor in an adjacent excerpt.
2685                if !kept_position {
2686                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
2687                        if excerpt.contains(&anchor) {
2688                            anchor.excerpt_id = excerpt.id;
2689                            kept_position = true;
2690                            break;
2691                        }
2692                    }
2693                }
2694
2695                // If there's no adjacent excerpt that contains the anchor's position,
2696                // then report that the anchor has lost its position.
2697                if !kept_position {
2698                    anchor = if let Some(excerpt) = next_excerpt {
2699                        let mut text_anchor = excerpt
2700                            .range
2701                            .context
2702                            .start
2703                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2704                        if text_anchor
2705                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
2706                            .is_gt()
2707                        {
2708                            text_anchor = excerpt.range.context.end;
2709                        }
2710                        Anchor {
2711                            buffer_id: Some(excerpt.buffer_id),
2712                            excerpt_id: excerpt.id,
2713                            text_anchor,
2714                        }
2715                    } else if let Some(excerpt) = prev_excerpt {
2716                        let mut text_anchor = excerpt
2717                            .range
2718                            .context
2719                            .end
2720                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2721                        if text_anchor
2722                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
2723                            .is_lt()
2724                        {
2725                            text_anchor = excerpt.range.context.start;
2726                        }
2727                        Anchor {
2728                            buffer_id: Some(excerpt.buffer_id),
2729                            excerpt_id: excerpt.id,
2730                            text_anchor,
2731                        }
2732                    } else if anchor.text_anchor.bias == Bias::Left {
2733                        Anchor::min()
2734                    } else {
2735                        Anchor::max()
2736                    };
2737                }
2738
2739                result.push((anchor_ix, anchor, kept_position));
2740            }
2741        }
2742        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
2743        result
2744    }
2745
2746    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2747        self.anchor_at(position, Bias::Left)
2748    }
2749
2750    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2751        self.anchor_at(position, Bias::Right)
2752    }
2753
2754    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
2755        let offset = position.to_offset(self);
2756        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
2757            return Anchor {
2758                buffer_id: Some(buffer_id),
2759                excerpt_id: *excerpt_id,
2760                text_anchor: buffer.anchor_at(offset, bias),
2761            };
2762        }
2763
2764        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>();
2765        cursor.seek(&offset, Bias::Right, &());
2766        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
2767            cursor.prev(&());
2768        }
2769        if let Some(excerpt) = cursor.item() {
2770            let mut overshoot = offset.saturating_sub(cursor.start().0);
2771            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
2772                overshoot -= 1;
2773                bias = Bias::Right;
2774            }
2775
2776            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2777            let text_anchor =
2778                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
2779            Anchor {
2780                buffer_id: Some(excerpt.buffer_id),
2781                excerpt_id: excerpt.id,
2782                text_anchor,
2783            }
2784        } else if offset == 0 && bias == Bias::Left {
2785            Anchor::min()
2786        } else {
2787            Anchor::max()
2788        }
2789    }
2790
2791    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
2792        let locator = self.excerpt_locator_for_id(excerpt_id);
2793        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2794        cursor.seek(locator, Bias::Left, &());
2795        if let Some(excerpt) = cursor.item() {
2796            if excerpt.id == excerpt_id {
2797                let text_anchor = excerpt.clip_anchor(text_anchor);
2798                drop(cursor);
2799                return Anchor {
2800                    buffer_id: Some(excerpt.buffer_id),
2801                    excerpt_id,
2802                    text_anchor,
2803                };
2804            }
2805        }
2806        panic!("excerpt not found");
2807    }
2808
2809    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2810        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
2811            true
2812        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
2813            excerpt.buffer.can_resolve(&anchor.text_anchor)
2814        } else {
2815            false
2816        }
2817    }
2818
2819    pub fn excerpts(
2820        &self,
2821    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
2822        self.excerpts
2823            .iter()
2824            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
2825    }
2826
2827    fn excerpts_for_range<T: ToOffset>(
2828        &self,
2829        range: Range<T>,
2830    ) -> impl Iterator<Item = (&Excerpt, usize)> + '_ {
2831        let range = range.start.to_offset(self)..range.end.to_offset(self);
2832
2833        let mut cursor = self.excerpts.cursor::<usize>();
2834        cursor.seek(&range.start, Bias::Right, &());
2835        cursor.prev(&());
2836
2837        iter::from_fn(move || {
2838            cursor.next(&());
2839            if cursor.start() < &range.end {
2840                cursor.item().map(|item| (item, *cursor.start()))
2841            } else {
2842                None
2843            }
2844        })
2845    }
2846
2847    pub fn excerpt_boundaries_in_range<R, T>(
2848        &self,
2849        range: R,
2850    ) -> impl Iterator<Item = ExcerptBoundary> + '_
2851    where
2852        R: RangeBounds<T>,
2853        T: ToOffset,
2854    {
2855        let start_offset;
2856        let start = match range.start_bound() {
2857            Bound::Included(start) => {
2858                start_offset = start.to_offset(self);
2859                Bound::Included(start_offset)
2860            }
2861            Bound::Excluded(start) => {
2862                start_offset = start.to_offset(self);
2863                Bound::Excluded(start_offset)
2864            }
2865            Bound::Unbounded => {
2866                start_offset = 0;
2867                Bound::Unbounded
2868            }
2869        };
2870        let end = match range.end_bound() {
2871            Bound::Included(end) => Bound::Included(end.to_offset(self)),
2872            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
2873            Bound::Unbounded => Bound::Unbounded,
2874        };
2875        let bounds = (start, end);
2876
2877        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2878        cursor.seek(&start_offset, Bias::Right, &());
2879        if cursor.item().is_none() {
2880            cursor.prev(&());
2881        }
2882        if !bounds.contains(&cursor.start().0) {
2883            cursor.next(&());
2884        }
2885
2886        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
2887        std::iter::from_fn(move || {
2888            if self.singleton {
2889                None
2890            } else if bounds.contains(&cursor.start().0) {
2891                let excerpt = cursor.item()?;
2892                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
2893                let boundary = ExcerptBoundary {
2894                    id: excerpt.id,
2895                    row: cursor.start().1.row,
2896                    buffer: excerpt.buffer.clone(),
2897                    range: excerpt.range.clone(),
2898                    starts_new_buffer,
2899                };
2900
2901                prev_buffer_id = Some(excerpt.buffer_id);
2902                cursor.next(&());
2903                Some(boundary)
2904            } else {
2905                None
2906            }
2907        })
2908    }
2909
2910    pub fn edit_count(&self) -> usize {
2911        self.edit_count
2912    }
2913
2914    pub fn parse_count(&self) -> usize {
2915        self.parse_count
2916    }
2917
2918    /// Returns the smallest enclosing bracket ranges containing the given range or
2919    /// None if no brackets contain range or the range is not contained in a single
2920    /// excerpt
2921    ///
2922    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
2923    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
2924        &self,
2925        range: Range<T>,
2926        range_filter: Option<&dyn Fn(Range<usize>, Range<usize>) -> bool>,
2927    ) -> Option<(Range<usize>, Range<usize>)> {
2928        let range = range.start.to_offset(self)..range.end.to_offset(self);
2929        let excerpt = self.excerpt_containing(range.clone())?;
2930
2931        // Filter to ranges contained in the excerpt
2932        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
2933            excerpt.contains_buffer_range(open.start..close.end)
2934                && range_filter.map_or(true, |filter| {
2935                    filter(
2936                        excerpt.map_range_from_buffer(open),
2937                        excerpt.map_range_from_buffer(close),
2938                    )
2939                })
2940        };
2941
2942        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
2943            excerpt.map_range_to_buffer(range),
2944            Some(&range_filter),
2945        )?;
2946
2947        Some((
2948            excerpt.map_range_from_buffer(open),
2949            excerpt.map_range_from_buffer(close),
2950        ))
2951    }
2952
2953    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
2954    /// not contained in a single excerpt
2955    pub fn enclosing_bracket_ranges<T: ToOffset>(
2956        &self,
2957        range: Range<T>,
2958    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
2959        let range = range.start.to_offset(self)..range.end.to_offset(self);
2960        let excerpt = self.excerpt_containing(range.clone())?;
2961
2962        Some(
2963            excerpt
2964                .buffer()
2965                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
2966                .filter(move |(open, close)| excerpt.contains_buffer_range(open.start..close.end)),
2967        )
2968    }
2969
2970    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
2971    /// not contained in a single excerpt
2972    pub fn bracket_ranges<T: ToOffset>(
2973        &self,
2974        range: Range<T>,
2975    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
2976        let range = range.start.to_offset(self)..range.end.to_offset(self);
2977        let excerpt = self.excerpt_containing(range.clone())?;
2978
2979        Some(
2980            excerpt
2981                .buffer()
2982                .bracket_ranges(excerpt.map_range_to_buffer(range))
2983                .filter_map(move |(start_bracket_range, close_bracket_range)| {
2984                    let buffer_range = start_bracket_range.start..close_bracket_range.end;
2985                    if excerpt.contains_buffer_range(buffer_range) {
2986                        Some((
2987                            excerpt.map_range_from_buffer(start_bracket_range),
2988                            excerpt.map_range_from_buffer(close_bracket_range),
2989                        ))
2990                    } else {
2991                        None
2992                    }
2993                }),
2994        )
2995    }
2996
2997    pub fn redacted_ranges<'a, T: ToOffset>(
2998        &'a self,
2999        range: Range<T>,
3000        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
3001    ) -> impl Iterator<Item = Range<usize>> + 'a {
3002        let range = range.start.to_offset(self)..range.end.to_offset(self);
3003        self.excerpts_for_range(range.clone())
3004            .filter_map(move |(excerpt, excerpt_offset)| {
3005                redaction_enabled(excerpt.buffer.file()).then(move || {
3006                    let excerpt_buffer_start =
3007                        excerpt.range.context.start.to_offset(&excerpt.buffer);
3008
3009                    excerpt
3010                        .buffer
3011                        .redacted_ranges(excerpt.range.context.clone())
3012                        .map(move |mut redacted_range| {
3013                            // Re-base onto the excerpts coordinates in the multibuffer
3014                            redacted_range.start =
3015                                excerpt_offset + (redacted_range.start - excerpt_buffer_start);
3016                            redacted_range.end =
3017                                excerpt_offset + (redacted_range.end - excerpt_buffer_start);
3018
3019                            redacted_range
3020                        })
3021                        .skip_while(move |redacted_range| redacted_range.end < range.start)
3022                        .take_while(move |redacted_range| redacted_range.start < range.end)
3023                })
3024            })
3025            .flatten()
3026    }
3027
3028    pub fn diagnostics_update_count(&self) -> usize {
3029        self.diagnostics_update_count
3030    }
3031
3032    pub fn git_diff_update_count(&self) -> usize {
3033        self.git_diff_update_count
3034    }
3035
3036    pub fn trailing_excerpt_update_count(&self) -> usize {
3037        self.trailing_excerpt_update_count
3038    }
3039
3040    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
3041        self.point_to_buffer_offset(point)
3042            .and_then(|(buffer, _)| buffer.file())
3043    }
3044
3045    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
3046        self.point_to_buffer_offset(point)
3047            .and_then(|(buffer, offset)| buffer.language_at(offset))
3048    }
3049
3050    pub fn settings_at<'a, T: ToOffset>(
3051        &'a self,
3052        point: T,
3053        cx: &'a AppContext,
3054    ) -> &'a LanguageSettings {
3055        let mut language = None;
3056        let mut file = None;
3057        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
3058            language = buffer.language_at(offset);
3059            file = buffer.file();
3060        }
3061        language_settings(language, file, cx)
3062    }
3063
3064    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
3065        self.point_to_buffer_offset(point)
3066            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
3067    }
3068
3069    pub fn language_indent_size_at<T: ToOffset>(
3070        &self,
3071        position: T,
3072        cx: &AppContext,
3073    ) -> Option<IndentSize> {
3074        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
3075        Some(buffer_snapshot.language_indent_size_at(offset, cx))
3076    }
3077
3078    pub fn is_dirty(&self) -> bool {
3079        self.is_dirty
3080    }
3081
3082    pub fn has_conflict(&self) -> bool {
3083        self.has_conflict
3084    }
3085
3086    pub fn has_diagnostics(&self) -> bool {
3087        self.excerpts
3088            .iter()
3089            .any(|excerpt| excerpt.buffer.has_diagnostics())
3090    }
3091
3092    pub fn diagnostic_group<'a, O>(
3093        &'a self,
3094        group_id: usize,
3095    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3096    where
3097        O: text::FromAnchor + 'a,
3098    {
3099        self.as_singleton()
3100            .into_iter()
3101            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
3102    }
3103
3104    pub fn diagnostics_in_range<'a, T, O>(
3105        &'a self,
3106        range: Range<T>,
3107        reversed: bool,
3108    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3109    where
3110        T: 'a + ToOffset,
3111        O: 'a + text::FromAnchor + Ord,
3112    {
3113        self.as_singleton()
3114            .into_iter()
3115            .flat_map(move |(_, _, buffer)| {
3116                buffer.diagnostics_in_range(
3117                    range.start.to_offset(self)..range.end.to_offset(self),
3118                    reversed,
3119                )
3120            })
3121    }
3122
3123    pub fn has_git_diffs(&self) -> bool {
3124        for excerpt in self.excerpts.iter() {
3125            if excerpt.buffer.has_git_diff() {
3126                return true;
3127            }
3128        }
3129        false
3130    }
3131
3132    pub fn git_diff_hunks_in_range_rev(
3133        &self,
3134        row_range: Range<u32>,
3135    ) -> impl Iterator<Item = DiffHunk<u32>> + '_ {
3136        let mut cursor = self.excerpts.cursor::<Point>();
3137
3138        cursor.seek(&Point::new(row_range.end, 0), Bias::Left, &());
3139        if cursor.item().is_none() {
3140            cursor.prev(&());
3141        }
3142
3143        std::iter::from_fn(move || {
3144            let excerpt = cursor.item()?;
3145            let multibuffer_start = *cursor.start();
3146            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3147            if multibuffer_start.row >= row_range.end {
3148                return None;
3149            }
3150
3151            let mut buffer_start = excerpt.range.context.start;
3152            let mut buffer_end = excerpt.range.context.end;
3153            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3154            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3155
3156            if row_range.start > multibuffer_start.row {
3157                let buffer_start_point =
3158                    excerpt_start_point + Point::new(row_range.start - multibuffer_start.row, 0);
3159                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3160            }
3161
3162            if row_range.end < multibuffer_end.row {
3163                let buffer_end_point =
3164                    excerpt_start_point + Point::new(row_range.end - multibuffer_start.row, 0);
3165                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3166            }
3167
3168            let buffer_hunks = excerpt
3169                .buffer
3170                .git_diff_hunks_intersecting_range_rev(buffer_start..buffer_end)
3171                .map(move |hunk| {
3172                    let start = multibuffer_start.row
3173                        + hunk
3174                            .buffer_range
3175                            .start
3176                            .saturating_sub(excerpt_start_point.row);
3177                    let end = multibuffer_start.row
3178                        + hunk
3179                            .buffer_range
3180                            .end
3181                            .min(excerpt_end_point.row + 1)
3182                            .saturating_sub(excerpt_start_point.row);
3183
3184                    DiffHunk {
3185                        buffer_range: start..end,
3186                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3187                    }
3188                });
3189
3190            cursor.prev(&());
3191
3192            Some(buffer_hunks)
3193        })
3194        .flatten()
3195    }
3196
3197    pub fn git_diff_hunks_in_range(
3198        &self,
3199        row_range: Range<u32>,
3200    ) -> impl Iterator<Item = DiffHunk<u32>> + '_ {
3201        let mut cursor = self.excerpts.cursor::<Point>();
3202
3203        cursor.seek(&Point::new(row_range.start, 0), Bias::Right, &());
3204
3205        std::iter::from_fn(move || {
3206            let excerpt = cursor.item()?;
3207            let multibuffer_start = *cursor.start();
3208            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3209            if multibuffer_start.row >= row_range.end {
3210                return None;
3211            }
3212
3213            let mut buffer_start = excerpt.range.context.start;
3214            let mut buffer_end = excerpt.range.context.end;
3215            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3216            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3217
3218            if row_range.start > multibuffer_start.row {
3219                let buffer_start_point =
3220                    excerpt_start_point + Point::new(row_range.start - multibuffer_start.row, 0);
3221                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3222            }
3223
3224            if row_range.end < multibuffer_end.row {
3225                let buffer_end_point =
3226                    excerpt_start_point + Point::new(row_range.end - multibuffer_start.row, 0);
3227                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3228            }
3229
3230            let buffer_hunks = excerpt
3231                .buffer
3232                .git_diff_hunks_intersecting_range(buffer_start..buffer_end)
3233                .map(move |hunk| {
3234                    let start = multibuffer_start.row
3235                        + hunk
3236                            .buffer_range
3237                            .start
3238                            .saturating_sub(excerpt_start_point.row);
3239                    let end = multibuffer_start.row
3240                        + hunk
3241                            .buffer_range
3242                            .end
3243                            .min(excerpt_end_point.row + 1)
3244                            .saturating_sub(excerpt_start_point.row);
3245
3246                    DiffHunk {
3247                        buffer_range: start..end,
3248                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3249                    }
3250                });
3251
3252            cursor.next(&());
3253
3254            Some(buffer_hunks)
3255        })
3256        .flatten()
3257    }
3258
3259    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
3260        let range = range.start.to_offset(self)..range.end.to_offset(self);
3261        let excerpt = self.excerpt_containing(range.clone())?;
3262
3263        let ancestor_buffer_range = excerpt
3264            .buffer()
3265            .range_for_syntax_ancestor(excerpt.map_range_to_buffer(range))?;
3266
3267        Some(excerpt.map_range_from_buffer(ancestor_buffer_range))
3268    }
3269
3270    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
3271        let (excerpt_id, _, buffer) = self.as_singleton()?;
3272        let outline = buffer.outline(theme)?;
3273        Some(Outline::new(
3274            outline
3275                .items
3276                .into_iter()
3277                .map(|item| OutlineItem {
3278                    depth: item.depth,
3279                    range: self.anchor_in_excerpt(*excerpt_id, item.range.start)
3280                        ..self.anchor_in_excerpt(*excerpt_id, item.range.end),
3281                    text: item.text,
3282                    highlight_ranges: item.highlight_ranges,
3283                    name_ranges: item.name_ranges,
3284                })
3285                .collect(),
3286        ))
3287    }
3288
3289    pub fn symbols_containing<T: ToOffset>(
3290        &self,
3291        offset: T,
3292        theme: Option<&SyntaxTheme>,
3293    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
3294        let anchor = self.anchor_before(offset);
3295        let excerpt_id = anchor.excerpt_id;
3296        let excerpt = self.excerpt(excerpt_id)?;
3297        Some((
3298            excerpt.buffer_id,
3299            excerpt
3300                .buffer
3301                .symbols_containing(anchor.text_anchor, theme)
3302                .into_iter()
3303                .flatten()
3304                .map(|item| OutlineItem {
3305                    depth: item.depth,
3306                    range: self.anchor_in_excerpt(excerpt_id, item.range.start)
3307                        ..self.anchor_in_excerpt(excerpt_id, item.range.end),
3308                    text: item.text,
3309                    highlight_ranges: item.highlight_ranges,
3310                    name_ranges: item.name_ranges,
3311                })
3312                .collect(),
3313        ))
3314    }
3315
3316    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
3317        if id == ExcerptId::min() {
3318            Locator::min_ref()
3319        } else if id == ExcerptId::max() {
3320            Locator::max_ref()
3321        } else {
3322            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
3323            cursor.seek(&id, Bias::Left, &());
3324            if let Some(entry) = cursor.item() {
3325                if entry.id == id {
3326                    return &entry.locator;
3327                }
3328            }
3329            panic!("invalid excerpt id {:?}", id)
3330        }
3331    }
3332
3333    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
3334        Some(self.excerpt(excerpt_id)?.buffer_id)
3335    }
3336
3337    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
3338        Some(&self.excerpt(excerpt_id)?.buffer)
3339    }
3340
3341    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
3342        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
3343        let locator = self.excerpt_locator_for_id(excerpt_id);
3344        cursor.seek(&Some(locator), Bias::Left, &());
3345        if let Some(excerpt) = cursor.item() {
3346            if excerpt.id == excerpt_id {
3347                return Some(excerpt);
3348            }
3349        }
3350        None
3351    }
3352
3353    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
3354    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
3355        let range = range.start.to_offset(self)..range.end.to_offset(self);
3356
3357        let mut cursor = self.excerpts.cursor::<usize>();
3358        cursor.seek(&range.start, Bias::Right, &());
3359        let start_excerpt = cursor.item()?;
3360
3361        if range.start == range.end {
3362            return Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()));
3363        }
3364
3365        cursor.seek(&range.end, Bias::Right, &());
3366        let end_excerpt = cursor.item()?;
3367
3368        if start_excerpt.id != end_excerpt.id {
3369            None
3370        } else {
3371            Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()))
3372        }
3373    }
3374
3375    pub fn remote_selections_in_range<'a>(
3376        &'a self,
3377        range: &'a Range<Anchor>,
3378    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
3379        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
3380        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
3381        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
3382        cursor.seek(start_locator, Bias::Left, &());
3383        cursor
3384            .take_while(move |excerpt| excerpt.locator <= *end_locator)
3385            .flat_map(move |excerpt| {
3386                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
3387                if excerpt.id == range.start.excerpt_id {
3388                    query_range.start = range.start.text_anchor;
3389                }
3390                if excerpt.id == range.end.excerpt_id {
3391                    query_range.end = range.end.text_anchor;
3392                }
3393
3394                excerpt
3395                    .buffer
3396                    .remote_selections_in_range(query_range)
3397                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
3398                        selections.map(move |selection| {
3399                            let mut start = Anchor {
3400                                buffer_id: Some(excerpt.buffer_id),
3401                                excerpt_id: excerpt.id,
3402                                text_anchor: selection.start,
3403                            };
3404                            let mut end = Anchor {
3405                                buffer_id: Some(excerpt.buffer_id),
3406                                excerpt_id: excerpt.id,
3407                                text_anchor: selection.end,
3408                            };
3409                            if range.start.cmp(&start, self).is_gt() {
3410                                start = range.start;
3411                            }
3412                            if range.end.cmp(&end, self).is_lt() {
3413                                end = range.end;
3414                            }
3415
3416                            (
3417                                replica_id,
3418                                line_mode,
3419                                cursor_shape,
3420                                Selection {
3421                                    id: selection.id,
3422                                    start,
3423                                    end,
3424                                    reversed: selection.reversed,
3425                                    goal: selection.goal,
3426                                },
3427                            )
3428                        })
3429                    })
3430            })
3431    }
3432}
3433
3434#[cfg(any(test, feature = "test-support"))]
3435impl MultiBufferSnapshot {
3436    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
3437        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
3438        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
3439        start..end
3440    }
3441}
3442
3443impl History {
3444    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
3445        self.transaction_depth += 1;
3446        if self.transaction_depth == 1 {
3447            let id = self.next_transaction_id.tick();
3448            self.undo_stack.push(Transaction {
3449                id,
3450                buffer_transactions: Default::default(),
3451                first_edit_at: now,
3452                last_edit_at: now,
3453                suppress_grouping: false,
3454            });
3455            Some(id)
3456        } else {
3457            None
3458        }
3459    }
3460
3461    fn end_transaction(
3462        &mut self,
3463        now: Instant,
3464        buffer_transactions: HashMap<BufferId, TransactionId>,
3465    ) -> bool {
3466        assert_ne!(self.transaction_depth, 0);
3467        self.transaction_depth -= 1;
3468        if self.transaction_depth == 0 {
3469            if buffer_transactions.is_empty() {
3470                self.undo_stack.pop();
3471                false
3472            } else {
3473                self.redo_stack.clear();
3474                let transaction = self.undo_stack.last_mut().unwrap();
3475                transaction.last_edit_at = now;
3476                for (buffer_id, transaction_id) in buffer_transactions {
3477                    transaction
3478                        .buffer_transactions
3479                        .entry(buffer_id)
3480                        .or_insert(transaction_id);
3481                }
3482                true
3483            }
3484        } else {
3485            false
3486        }
3487    }
3488
3489    fn push_transaction<'a, T>(
3490        &mut self,
3491        buffer_transactions: T,
3492        now: Instant,
3493        cx: &mut ModelContext<MultiBuffer>,
3494    ) where
3495        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
3496    {
3497        assert_eq!(self.transaction_depth, 0);
3498        let transaction = Transaction {
3499            id: self.next_transaction_id.tick(),
3500            buffer_transactions: buffer_transactions
3501                .into_iter()
3502                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
3503                .collect(),
3504            first_edit_at: now,
3505            last_edit_at: now,
3506            suppress_grouping: false,
3507        };
3508        if !transaction.buffer_transactions.is_empty() {
3509            self.undo_stack.push(transaction);
3510            self.redo_stack.clear();
3511        }
3512    }
3513
3514    fn finalize_last_transaction(&mut self) {
3515        if let Some(transaction) = self.undo_stack.last_mut() {
3516            transaction.suppress_grouping = true;
3517        }
3518    }
3519
3520    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
3521        if let Some(ix) = self
3522            .undo_stack
3523            .iter()
3524            .rposition(|transaction| transaction.id == transaction_id)
3525        {
3526            Some(self.undo_stack.remove(ix))
3527        } else if let Some(ix) = self
3528            .redo_stack
3529            .iter()
3530            .rposition(|transaction| transaction.id == transaction_id)
3531        {
3532            Some(self.redo_stack.remove(ix))
3533        } else {
3534            None
3535        }
3536    }
3537
3538    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
3539        self.undo_stack
3540            .iter_mut()
3541            .find(|transaction| transaction.id == transaction_id)
3542            .or_else(|| {
3543                self.redo_stack
3544                    .iter_mut()
3545                    .find(|transaction| transaction.id == transaction_id)
3546            })
3547    }
3548
3549    fn pop_undo(&mut self) -> Option<&mut Transaction> {
3550        assert_eq!(self.transaction_depth, 0);
3551        if let Some(transaction) = self.undo_stack.pop() {
3552            self.redo_stack.push(transaction);
3553            self.redo_stack.last_mut()
3554        } else {
3555            None
3556        }
3557    }
3558
3559    fn pop_redo(&mut self) -> Option<&mut Transaction> {
3560        assert_eq!(self.transaction_depth, 0);
3561        if let Some(transaction) = self.redo_stack.pop() {
3562            self.undo_stack.push(transaction);
3563            self.undo_stack.last_mut()
3564        } else {
3565            None
3566        }
3567    }
3568
3569    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
3570        let ix = self
3571            .undo_stack
3572            .iter()
3573            .rposition(|transaction| transaction.id == transaction_id)?;
3574        let transaction = self.undo_stack.remove(ix);
3575        self.redo_stack.push(transaction);
3576        self.redo_stack.last()
3577    }
3578
3579    fn group(&mut self) -> Option<TransactionId> {
3580        let mut count = 0;
3581        let mut transactions = self.undo_stack.iter();
3582        if let Some(mut transaction) = transactions.next_back() {
3583            while let Some(prev_transaction) = transactions.next_back() {
3584                if !prev_transaction.suppress_grouping
3585                    && transaction.first_edit_at - prev_transaction.last_edit_at
3586                        <= self.group_interval
3587                {
3588                    transaction = prev_transaction;
3589                    count += 1;
3590                } else {
3591                    break;
3592                }
3593            }
3594        }
3595        self.group_trailing(count)
3596    }
3597
3598    fn group_until(&mut self, transaction_id: TransactionId) {
3599        let mut count = 0;
3600        for transaction in self.undo_stack.iter().rev() {
3601            if transaction.id == transaction_id {
3602                self.group_trailing(count);
3603                break;
3604            } else if transaction.suppress_grouping {
3605                break;
3606            } else {
3607                count += 1;
3608            }
3609        }
3610    }
3611
3612    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
3613        let new_len = self.undo_stack.len() - n;
3614        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
3615        if let Some(last_transaction) = transactions_to_keep.last_mut() {
3616            if let Some(transaction) = transactions_to_merge.last() {
3617                last_transaction.last_edit_at = transaction.last_edit_at;
3618            }
3619            for to_merge in transactions_to_merge {
3620                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
3621                    last_transaction
3622                        .buffer_transactions
3623                        .entry(*buffer_id)
3624                        .or_insert(*transaction_id);
3625                }
3626            }
3627        }
3628
3629        self.undo_stack.truncate(new_len);
3630        self.undo_stack.last().map(|t| t.id)
3631    }
3632}
3633
3634impl Excerpt {
3635    fn new(
3636        id: ExcerptId,
3637        locator: Locator,
3638        buffer_id: BufferId,
3639        buffer: BufferSnapshot,
3640        range: ExcerptRange<text::Anchor>,
3641        has_trailing_newline: bool,
3642    ) -> Self {
3643        Excerpt {
3644            id,
3645            locator,
3646            max_buffer_row: range.context.end.to_point(&buffer).row,
3647            text_summary: buffer
3648                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
3649            buffer_id,
3650            buffer,
3651            range,
3652            has_trailing_newline,
3653        }
3654    }
3655
3656    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
3657        let content_start = self.range.context.start.to_offset(&self.buffer);
3658        let chunks_start = content_start + range.start;
3659        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
3660
3661        let footer_height = if self.has_trailing_newline
3662            && range.start <= self.text_summary.len
3663            && range.end > self.text_summary.len
3664        {
3665            1
3666        } else {
3667            0
3668        };
3669
3670        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
3671
3672        ExcerptChunks {
3673            content_chunks,
3674            footer_height,
3675        }
3676    }
3677
3678    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3679        let content_start = self.range.context.start.to_offset(&self.buffer);
3680        let bytes_start = content_start + range.start;
3681        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3682        let footer_height = if self.has_trailing_newline
3683            && range.start <= self.text_summary.len
3684            && range.end > self.text_summary.len
3685        {
3686            1
3687        } else {
3688            0
3689        };
3690        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
3691
3692        ExcerptBytes {
3693            content_bytes,
3694            footer_height,
3695        }
3696    }
3697
3698    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3699        let content_start = self.range.context.start.to_offset(&self.buffer);
3700        let bytes_start = content_start + range.start;
3701        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3702        let footer_height = if self.has_trailing_newline
3703            && range.start <= self.text_summary.len
3704            && range.end > self.text_summary.len
3705        {
3706            1
3707        } else {
3708            0
3709        };
3710        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
3711
3712        ExcerptBytes {
3713            content_bytes,
3714            footer_height,
3715        }
3716    }
3717
3718    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
3719        if text_anchor
3720            .cmp(&self.range.context.start, &self.buffer)
3721            .is_lt()
3722        {
3723            self.range.context.start
3724        } else if text_anchor
3725            .cmp(&self.range.context.end, &self.buffer)
3726            .is_gt()
3727        {
3728            self.range.context.end
3729        } else {
3730            text_anchor
3731        }
3732    }
3733
3734    fn contains(&self, anchor: &Anchor) -> bool {
3735        Some(self.buffer_id) == anchor.buffer_id
3736            && self
3737                .range
3738                .context
3739                .start
3740                .cmp(&anchor.text_anchor, &self.buffer)
3741                .is_le()
3742            && self
3743                .range
3744                .context
3745                .end
3746                .cmp(&anchor.text_anchor, &self.buffer)
3747                .is_ge()
3748    }
3749
3750    /// The [`Excerpt`]'s start offset in its [`Buffer`]
3751    fn buffer_start_offset(&self) -> usize {
3752        self.range.context.start.to_offset(&self.buffer)
3753    }
3754
3755    /// The [`Excerpt`]'s end offset in its [`Buffer`]
3756    fn buffer_end_offset(&self) -> usize {
3757        self.buffer_start_offset() + self.text_summary.len
3758    }
3759}
3760
3761impl<'a> MultiBufferExcerpt<'a> {
3762    fn new(excerpt: &'a Excerpt, excerpt_offset: usize) -> Self {
3763        MultiBufferExcerpt {
3764            excerpt,
3765            excerpt_offset,
3766        }
3767    }
3768
3769    pub fn buffer(&self) -> &'a BufferSnapshot {
3770        &self.excerpt.buffer
3771    }
3772
3773    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
3774    pub fn map_offset_to_buffer(&self, offset: usize) -> usize {
3775        self.excerpt.buffer_start_offset() + offset.saturating_sub(self.excerpt_offset)
3776    }
3777
3778    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
3779    pub fn map_range_to_buffer(&self, range: Range<usize>) -> Range<usize> {
3780        self.map_offset_to_buffer(range.start)..self.map_offset_to_buffer(range.end)
3781    }
3782
3783    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
3784    pub fn map_offset_from_buffer(&self, buffer_offset: usize) -> usize {
3785        let mut buffer_offset_in_excerpt =
3786            buffer_offset.saturating_sub(self.excerpt.buffer_start_offset());
3787        buffer_offset_in_excerpt =
3788            cmp::min(buffer_offset_in_excerpt, self.excerpt.text_summary.len);
3789
3790        self.excerpt_offset + buffer_offset_in_excerpt
3791    }
3792
3793    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
3794    pub fn map_range_from_buffer(&self, buffer_range: Range<usize>) -> Range<usize> {
3795        self.map_offset_from_buffer(buffer_range.start)
3796            ..self.map_offset_from_buffer(buffer_range.end)
3797    }
3798
3799    /// Returns true if the entirety of the given range is in the buffer's excerpt
3800    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
3801        range.start >= self.excerpt.buffer_start_offset()
3802            && range.end <= self.excerpt.buffer_end_offset()
3803    }
3804}
3805
3806impl ExcerptId {
3807    pub fn min() -> Self {
3808        Self(0)
3809    }
3810
3811    pub fn max() -> Self {
3812        Self(usize::MAX)
3813    }
3814
3815    pub fn to_proto(&self) -> u64 {
3816        self.0 as _
3817    }
3818
3819    pub fn from_proto(proto: u64) -> Self {
3820        Self(proto as _)
3821    }
3822
3823    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
3824        let a = snapshot.excerpt_locator_for_id(*self);
3825        let b = snapshot.excerpt_locator_for_id(*other);
3826        a.cmp(b).then_with(|| self.0.cmp(&other.0))
3827    }
3828}
3829
3830impl Into<usize> for ExcerptId {
3831    fn into(self) -> usize {
3832        self.0
3833    }
3834}
3835
3836impl fmt::Debug for Excerpt {
3837    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3838        f.debug_struct("Excerpt")
3839            .field("id", &self.id)
3840            .field("locator", &self.locator)
3841            .field("buffer_id", &self.buffer_id)
3842            .field("range", &self.range)
3843            .field("text_summary", &self.text_summary)
3844            .field("has_trailing_newline", &self.has_trailing_newline)
3845            .finish()
3846    }
3847}
3848
3849impl sum_tree::Item for Excerpt {
3850    type Summary = ExcerptSummary;
3851
3852    fn summary(&self) -> Self::Summary {
3853        let mut text = self.text_summary.clone();
3854        if self.has_trailing_newline {
3855            text += TextSummary::from("\n");
3856        }
3857        ExcerptSummary {
3858            excerpt_id: self.id,
3859            excerpt_locator: self.locator.clone(),
3860            max_buffer_row: self.max_buffer_row,
3861            text,
3862        }
3863    }
3864}
3865
3866impl sum_tree::Item for ExcerptIdMapping {
3867    type Summary = ExcerptId;
3868
3869    fn summary(&self) -> Self::Summary {
3870        self.id
3871    }
3872}
3873
3874impl sum_tree::KeyedItem for ExcerptIdMapping {
3875    type Key = ExcerptId;
3876
3877    fn key(&self) -> Self::Key {
3878        self.id
3879    }
3880}
3881
3882impl sum_tree::Summary for ExcerptId {
3883    type Context = ();
3884
3885    fn add_summary(&mut self, other: &Self, _: &()) {
3886        *self = *other;
3887    }
3888}
3889
3890impl sum_tree::Summary for ExcerptSummary {
3891    type Context = ();
3892
3893    fn add_summary(&mut self, summary: &Self, _: &()) {
3894        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
3895        self.excerpt_locator = summary.excerpt_locator.clone();
3896        self.text.add_summary(&summary.text, &());
3897        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
3898    }
3899}
3900
3901impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
3902    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3903        *self += &summary.text;
3904    }
3905}
3906
3907impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
3908    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3909        *self += summary.text.len;
3910    }
3911}
3912
3913impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
3914    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3915        Ord::cmp(self, &cursor_location.text.len)
3916    }
3917}
3918
3919impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
3920    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
3921        Ord::cmp(&Some(self), cursor_location)
3922    }
3923}
3924
3925impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
3926    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
3927        Ord::cmp(self, &cursor_location.excerpt_locator)
3928    }
3929}
3930
3931impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
3932    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3933        *self += summary.text.len_utf16;
3934    }
3935}
3936
3937impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
3938    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3939        *self += summary.text.lines;
3940    }
3941}
3942
3943impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
3944    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3945        *self += summary.text.lines_utf16()
3946    }
3947}
3948
3949impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
3950    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3951        *self = Some(&summary.excerpt_locator);
3952    }
3953}
3954
3955impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
3956    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
3957        *self = Some(summary.excerpt_id);
3958    }
3959}
3960
3961impl<'a> MultiBufferRows<'a> {
3962    pub fn seek(&mut self, row: u32) {
3963        self.buffer_row_range = 0..0;
3964
3965        self.excerpts
3966            .seek_forward(&Point::new(row, 0), Bias::Right, &());
3967        if self.excerpts.item().is_none() {
3968            self.excerpts.prev(&());
3969
3970            if self.excerpts.item().is_none() && row == 0 {
3971                self.buffer_row_range = 0..1;
3972                return;
3973            }
3974        }
3975
3976        if let Some(excerpt) = self.excerpts.item() {
3977            let overshoot = row - self.excerpts.start().row;
3978            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3979            self.buffer_row_range.start = excerpt_start + overshoot;
3980            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
3981        }
3982    }
3983}
3984
3985impl<'a> Iterator for MultiBufferRows<'a> {
3986    type Item = Option<u32>;
3987
3988    fn next(&mut self) -> Option<Self::Item> {
3989        loop {
3990            if !self.buffer_row_range.is_empty() {
3991                let row = Some(self.buffer_row_range.start);
3992                self.buffer_row_range.start += 1;
3993                return Some(row);
3994            }
3995            self.excerpts.item()?;
3996            self.excerpts.next(&());
3997            let excerpt = self.excerpts.item()?;
3998            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
3999            self.buffer_row_range.end =
4000                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
4001        }
4002    }
4003}
4004
4005impl<'a> MultiBufferChunks<'a> {
4006    pub fn offset(&self) -> usize {
4007        self.range.start
4008    }
4009
4010    pub fn seek(&mut self, offset: usize) {
4011        self.range.start = offset;
4012        self.excerpts.seek(&offset, Bias::Right, &());
4013        if let Some(excerpt) = self.excerpts.item() {
4014            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4015                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
4016                self.language_aware,
4017            ));
4018        } else {
4019            self.excerpt_chunks = None;
4020        }
4021    }
4022}
4023
4024impl<'a> Iterator for MultiBufferChunks<'a> {
4025    type Item = Chunk<'a>;
4026
4027    fn next(&mut self) -> Option<Self::Item> {
4028        if self.range.is_empty() {
4029            None
4030        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
4031            self.range.start += chunk.text.len();
4032            Some(chunk)
4033        } else {
4034            self.excerpts.next(&());
4035            let excerpt = self.excerpts.item()?;
4036            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4037                0..self.range.end - self.excerpts.start(),
4038                self.language_aware,
4039            ));
4040            self.next()
4041        }
4042    }
4043}
4044
4045impl<'a> MultiBufferBytes<'a> {
4046    fn consume(&mut self, len: usize) {
4047        self.range.start += len;
4048        self.chunk = &self.chunk[len..];
4049
4050        if !self.range.is_empty() && self.chunk.is_empty() {
4051            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4052                self.chunk = chunk;
4053            } else {
4054                self.excerpts.next(&());
4055                if let Some(excerpt) = self.excerpts.item() {
4056                    let mut excerpt_bytes =
4057                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4058                    self.chunk = excerpt_bytes.next().unwrap();
4059                    self.excerpt_bytes = Some(excerpt_bytes);
4060                }
4061            }
4062        }
4063    }
4064}
4065
4066impl<'a> Iterator for MultiBufferBytes<'a> {
4067    type Item = &'a [u8];
4068
4069    fn next(&mut self) -> Option<Self::Item> {
4070        let chunk = self.chunk;
4071        if chunk.is_empty() {
4072            None
4073        } else {
4074            self.consume(chunk.len());
4075            Some(chunk)
4076        }
4077    }
4078}
4079
4080impl<'a> io::Read for MultiBufferBytes<'a> {
4081    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4082        let len = cmp::min(buf.len(), self.chunk.len());
4083        buf[..len].copy_from_slice(&self.chunk[..len]);
4084        if len > 0 {
4085            self.consume(len);
4086        }
4087        Ok(len)
4088    }
4089}
4090
4091impl<'a> ReversedMultiBufferBytes<'a> {
4092    fn consume(&mut self, len: usize) {
4093        self.range.end -= len;
4094        self.chunk = &self.chunk[..self.chunk.len() - len];
4095
4096        if !self.range.is_empty() && self.chunk.is_empty() {
4097            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4098                self.chunk = chunk;
4099            } else {
4100                self.excerpts.next(&());
4101                if let Some(excerpt) = self.excerpts.item() {
4102                    let mut excerpt_bytes =
4103                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4104                    self.chunk = excerpt_bytes.next().unwrap();
4105                    self.excerpt_bytes = Some(excerpt_bytes);
4106                }
4107            }
4108        }
4109    }
4110}
4111
4112impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
4113    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4114        let len = cmp::min(buf.len(), self.chunk.len());
4115        buf[..len].copy_from_slice(&self.chunk[..len]);
4116        buf[..len].reverse();
4117        if len > 0 {
4118            self.consume(len);
4119        }
4120        Ok(len)
4121    }
4122}
4123impl<'a> Iterator for ExcerptBytes<'a> {
4124    type Item = &'a [u8];
4125
4126    fn next(&mut self) -> Option<Self::Item> {
4127        if let Some(chunk) = self.content_bytes.next() {
4128            if !chunk.is_empty() {
4129                return Some(chunk);
4130            }
4131        }
4132
4133        if self.footer_height > 0 {
4134            let result = &NEWLINES[..self.footer_height];
4135            self.footer_height = 0;
4136            return Some(result);
4137        }
4138
4139        None
4140    }
4141}
4142
4143impl<'a> Iterator for ExcerptChunks<'a> {
4144    type Item = Chunk<'a>;
4145
4146    fn next(&mut self) -> Option<Self::Item> {
4147        if let Some(chunk) = self.content_chunks.next() {
4148            return Some(chunk);
4149        }
4150
4151        if self.footer_height > 0 {
4152            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
4153            self.footer_height = 0;
4154            return Some(Chunk {
4155                text,
4156                ..Default::default()
4157            });
4158        }
4159
4160        None
4161    }
4162}
4163
4164impl ToOffset for Point {
4165    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4166        snapshot.point_to_offset(*self)
4167    }
4168}
4169
4170impl ToOffset for usize {
4171    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4172        assert!(*self <= snapshot.len(), "offset is out of range");
4173        *self
4174    }
4175}
4176
4177impl ToOffset for OffsetUtf16 {
4178    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4179        snapshot.offset_utf16_to_offset(*self)
4180    }
4181}
4182
4183impl ToOffset for PointUtf16 {
4184    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4185        snapshot.point_utf16_to_offset(*self)
4186    }
4187}
4188
4189impl ToOffsetUtf16 for OffsetUtf16 {
4190    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4191        *self
4192    }
4193}
4194
4195impl ToOffsetUtf16 for usize {
4196    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4197        snapshot.offset_to_offset_utf16(*self)
4198    }
4199}
4200
4201impl ToPoint for usize {
4202    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
4203        snapshot.offset_to_point(*self)
4204    }
4205}
4206
4207impl ToPoint for Point {
4208    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
4209        *self
4210    }
4211}
4212
4213impl ToPointUtf16 for usize {
4214    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4215        snapshot.offset_to_point_utf16(*self)
4216    }
4217}
4218
4219impl ToPointUtf16 for Point {
4220    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4221        snapshot.point_to_point_utf16(*self)
4222    }
4223}
4224
4225impl ToPointUtf16 for PointUtf16 {
4226    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
4227        *self
4228    }
4229}
4230
4231fn build_excerpt_ranges<T>(
4232    buffer: &BufferSnapshot,
4233    ranges: &[Range<T>],
4234    context_line_count: u32,
4235) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
4236where
4237    T: text::ToPoint,
4238{
4239    let max_point = buffer.max_point();
4240    let mut range_counts = Vec::new();
4241    let mut excerpt_ranges = Vec::new();
4242    let mut range_iter = ranges
4243        .iter()
4244        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
4245        .peekable();
4246    while let Some(range) = range_iter.next() {
4247        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
4248        let mut excerpt_end = Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
4249        let mut ranges_in_excerpt = 1;
4250
4251        while let Some(next_range) = range_iter.peek() {
4252            if next_range.start.row <= excerpt_end.row + context_line_count {
4253                excerpt_end =
4254                    Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
4255                ranges_in_excerpt += 1;
4256                range_iter.next();
4257            } else {
4258                break;
4259            }
4260        }
4261
4262        excerpt_ranges.push(ExcerptRange {
4263            context: excerpt_start..excerpt_end,
4264            primary: Some(range),
4265        });
4266        range_counts.push(ranges_in_excerpt);
4267    }
4268
4269    (excerpt_ranges, range_counts)
4270}
4271
4272#[cfg(test)]
4273mod tests {
4274    use super::*;
4275    use futures::StreamExt;
4276    use gpui::{AppContext, Context, TestAppContext};
4277    use language::{Buffer, Rope};
4278    use parking_lot::RwLock;
4279    use rand::prelude::*;
4280    use settings::SettingsStore;
4281    use std::env;
4282    use util::test::sample_text;
4283
4284    #[gpui::test]
4285    fn test_singleton(cx: &mut AppContext) {
4286        let buffer = cx.new_model(|cx| {
4287            Buffer::new(
4288                0,
4289                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4290                sample_text(6, 6, 'a'),
4291            )
4292        });
4293        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4294
4295        let snapshot = multibuffer.read(cx).snapshot(cx);
4296        assert_eq!(snapshot.text(), buffer.read(cx).text());
4297
4298        assert_eq!(
4299            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4300            (0..buffer.read(cx).row_count())
4301                .map(Some)
4302                .collect::<Vec<_>>()
4303        );
4304
4305        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
4306        let snapshot = multibuffer.read(cx).snapshot(cx);
4307
4308        assert_eq!(snapshot.text(), buffer.read(cx).text());
4309        assert_eq!(
4310            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4311            (0..buffer.read(cx).row_count())
4312                .map(Some)
4313                .collect::<Vec<_>>()
4314        );
4315    }
4316
4317    #[gpui::test]
4318    fn test_remote(cx: &mut AppContext) {
4319        let host_buffer =
4320            cx.new_model(|cx| Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "a"));
4321        let guest_buffer = cx.new_model(|cx| {
4322            let state = host_buffer.read(cx).to_proto();
4323            let ops = cx
4324                .background_executor()
4325                .block(host_buffer.read(cx).serialize_ops(None, cx));
4326            let mut buffer = Buffer::from_proto(1, Capability::ReadWrite, state, None).unwrap();
4327            buffer
4328                .apply_ops(
4329                    ops.into_iter()
4330                        .map(|op| language::proto::deserialize_operation(op).unwrap()),
4331                    cx,
4332                )
4333                .unwrap();
4334            buffer
4335        });
4336        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
4337        let snapshot = multibuffer.read(cx).snapshot(cx);
4338        assert_eq!(snapshot.text(), "a");
4339
4340        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
4341        let snapshot = multibuffer.read(cx).snapshot(cx);
4342        assert_eq!(snapshot.text(), "ab");
4343
4344        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
4345        let snapshot = multibuffer.read(cx).snapshot(cx);
4346        assert_eq!(snapshot.text(), "abc");
4347    }
4348
4349    #[gpui::test]
4350    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
4351        let buffer_1 = cx.new_model(|cx| {
4352            Buffer::new(
4353                0,
4354                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4355                sample_text(6, 6, 'a'),
4356            )
4357        });
4358        let buffer_2 = cx.new_model(|cx| {
4359            Buffer::new(
4360                0,
4361                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4362                sample_text(6, 6, 'g'),
4363            )
4364        });
4365        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4366
4367        let events = Arc::new(RwLock::new(Vec::<Event>::new()));
4368        multibuffer.update(cx, |_, cx| {
4369            let events = events.clone();
4370            cx.subscribe(&multibuffer, move |_, _, event, _| {
4371                if let Event::Edited { .. } = event {
4372                    events.write().push(event.clone())
4373                }
4374            })
4375            .detach();
4376        });
4377
4378        let subscription = multibuffer.update(cx, |multibuffer, cx| {
4379            let subscription = multibuffer.subscribe();
4380            multibuffer.push_excerpts(
4381                buffer_1.clone(),
4382                [ExcerptRange {
4383                    context: Point::new(1, 2)..Point::new(2, 5),
4384                    primary: None,
4385                }],
4386                cx,
4387            );
4388            assert_eq!(
4389                subscription.consume().into_inner(),
4390                [Edit {
4391                    old: 0..0,
4392                    new: 0..10
4393                }]
4394            );
4395
4396            multibuffer.push_excerpts(
4397                buffer_1.clone(),
4398                [ExcerptRange {
4399                    context: Point::new(3, 3)..Point::new(4, 4),
4400                    primary: None,
4401                }],
4402                cx,
4403            );
4404            multibuffer.push_excerpts(
4405                buffer_2.clone(),
4406                [ExcerptRange {
4407                    context: Point::new(3, 1)..Point::new(3, 3),
4408                    primary: None,
4409                }],
4410                cx,
4411            );
4412            assert_eq!(
4413                subscription.consume().into_inner(),
4414                [Edit {
4415                    old: 10..10,
4416                    new: 10..22
4417                }]
4418            );
4419
4420            subscription
4421        });
4422
4423        // Adding excerpts emits an edited event.
4424        assert_eq!(
4425            events.read().as_slice(),
4426            &[
4427                Event::Edited {
4428                    singleton_buffer_edited: false
4429                },
4430                Event::Edited {
4431                    singleton_buffer_edited: false
4432                },
4433                Event::Edited {
4434                    singleton_buffer_edited: false
4435                }
4436            ]
4437        );
4438
4439        let snapshot = multibuffer.read(cx).snapshot(cx);
4440        assert_eq!(
4441            snapshot.text(),
4442            concat!(
4443                "bbbb\n",  // Preserve newlines
4444                "ccccc\n", //
4445                "ddd\n",   //
4446                "eeee\n",  //
4447                "jj"       //
4448            )
4449        );
4450        assert_eq!(
4451            snapshot.buffer_rows(0).collect::<Vec<_>>(),
4452            [Some(1), Some(2), Some(3), Some(4), Some(3)]
4453        );
4454        assert_eq!(
4455            snapshot.buffer_rows(2).collect::<Vec<_>>(),
4456            [Some(3), Some(4), Some(3)]
4457        );
4458        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
4459        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
4460
4461        assert_eq!(
4462            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
4463            &[
4464                (0, "bbbb\nccccc".to_string(), true),
4465                (2, "ddd\neeee".to_string(), false),
4466                (4, "jj".to_string(), true),
4467            ]
4468        );
4469        assert_eq!(
4470            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
4471            &[(0, "bbbb\nccccc".to_string(), true)]
4472        );
4473        assert_eq!(
4474            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
4475            &[]
4476        );
4477        assert_eq!(
4478            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
4479            &[]
4480        );
4481        assert_eq!(
4482            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4483            &[(2, "ddd\neeee".to_string(), false)]
4484        );
4485        assert_eq!(
4486            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4487            &[(2, "ddd\neeee".to_string(), false)]
4488        );
4489        assert_eq!(
4490            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
4491            &[(2, "ddd\neeee".to_string(), false)]
4492        );
4493        assert_eq!(
4494            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
4495            &[(4, "jj".to_string(), true)]
4496        );
4497        assert_eq!(
4498            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
4499            &[]
4500        );
4501
4502        buffer_1.update(cx, |buffer, cx| {
4503            let text = "\n";
4504            buffer.edit(
4505                [
4506                    (Point::new(0, 0)..Point::new(0, 0), text),
4507                    (Point::new(2, 1)..Point::new(2, 3), text),
4508                ],
4509                None,
4510                cx,
4511            );
4512        });
4513
4514        let snapshot = multibuffer.read(cx).snapshot(cx);
4515        assert_eq!(
4516            snapshot.text(),
4517            concat!(
4518                "bbbb\n", // Preserve newlines
4519                "c\n",    //
4520                "cc\n",   //
4521                "ddd\n",  //
4522                "eeee\n", //
4523                "jj"      //
4524            )
4525        );
4526
4527        assert_eq!(
4528            subscription.consume().into_inner(),
4529            [Edit {
4530                old: 6..8,
4531                new: 6..7
4532            }]
4533        );
4534
4535        let snapshot = multibuffer.read(cx).snapshot(cx);
4536        assert_eq!(
4537            snapshot.clip_point(Point::new(0, 5), Bias::Left),
4538            Point::new(0, 4)
4539        );
4540        assert_eq!(
4541            snapshot.clip_point(Point::new(0, 5), Bias::Right),
4542            Point::new(0, 4)
4543        );
4544        assert_eq!(
4545            snapshot.clip_point(Point::new(5, 1), Bias::Right),
4546            Point::new(5, 1)
4547        );
4548        assert_eq!(
4549            snapshot.clip_point(Point::new(5, 2), Bias::Right),
4550            Point::new(5, 2)
4551        );
4552        assert_eq!(
4553            snapshot.clip_point(Point::new(5, 3), Bias::Right),
4554            Point::new(5, 2)
4555        );
4556
4557        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
4558            let (buffer_2_excerpt_id, _) =
4559                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
4560            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
4561            multibuffer.snapshot(cx)
4562        });
4563
4564        assert_eq!(
4565            snapshot.text(),
4566            concat!(
4567                "bbbb\n", // Preserve newlines
4568                "c\n",    //
4569                "cc\n",   //
4570                "ddd\n",  //
4571                "eeee",   //
4572            )
4573        );
4574
4575        fn boundaries_in_range(
4576            range: Range<Point>,
4577            snapshot: &MultiBufferSnapshot,
4578        ) -> Vec<(u32, String, bool)> {
4579            snapshot
4580                .excerpt_boundaries_in_range(range)
4581                .map(|boundary| {
4582                    (
4583                        boundary.row,
4584                        boundary
4585                            .buffer
4586                            .text_for_range(boundary.range.context)
4587                            .collect::<String>(),
4588                        boundary.starts_new_buffer,
4589                    )
4590                })
4591                .collect::<Vec<_>>()
4592        }
4593    }
4594
4595    #[gpui::test]
4596    fn test_excerpt_events(cx: &mut AppContext) {
4597        let buffer_1 = cx.new_model(|cx| {
4598            Buffer::new(
4599                0,
4600                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4601                sample_text(10, 3, 'a'),
4602            )
4603        });
4604        let buffer_2 = cx.new_model(|cx| {
4605            Buffer::new(
4606                0,
4607                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4608                sample_text(10, 3, 'm'),
4609            )
4610        });
4611
4612        let leader_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4613        let follower_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4614        let follower_edit_event_count = Arc::new(RwLock::new(0));
4615
4616        follower_multibuffer.update(cx, |_, cx| {
4617            let follower_edit_event_count = follower_edit_event_count.clone();
4618            cx.subscribe(
4619                &leader_multibuffer,
4620                move |follower, _, event, cx| match event.clone() {
4621                    Event::ExcerptsAdded {
4622                        buffer,
4623                        predecessor,
4624                        excerpts,
4625                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
4626                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
4627                    Event::Edited { .. } => {
4628                        *follower_edit_event_count.write() += 1;
4629                    }
4630                    _ => {}
4631                },
4632            )
4633            .detach();
4634        });
4635
4636        leader_multibuffer.update(cx, |leader, cx| {
4637            leader.push_excerpts(
4638                buffer_1.clone(),
4639                [
4640                    ExcerptRange {
4641                        context: 0..8,
4642                        primary: None,
4643                    },
4644                    ExcerptRange {
4645                        context: 12..16,
4646                        primary: None,
4647                    },
4648                ],
4649                cx,
4650            );
4651            leader.insert_excerpts_after(
4652                leader.excerpt_ids()[0],
4653                buffer_2.clone(),
4654                [
4655                    ExcerptRange {
4656                        context: 0..5,
4657                        primary: None,
4658                    },
4659                    ExcerptRange {
4660                        context: 10..15,
4661                        primary: None,
4662                    },
4663                ],
4664                cx,
4665            )
4666        });
4667        assert_eq!(
4668            leader_multibuffer.read(cx).snapshot(cx).text(),
4669            follower_multibuffer.read(cx).snapshot(cx).text(),
4670        );
4671        assert_eq!(*follower_edit_event_count.read(), 2);
4672
4673        leader_multibuffer.update(cx, |leader, cx| {
4674            let excerpt_ids = leader.excerpt_ids();
4675            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
4676        });
4677        assert_eq!(
4678            leader_multibuffer.read(cx).snapshot(cx).text(),
4679            follower_multibuffer.read(cx).snapshot(cx).text(),
4680        );
4681        assert_eq!(*follower_edit_event_count.read(), 3);
4682
4683        // Removing an empty set of excerpts is a noop.
4684        leader_multibuffer.update(cx, |leader, cx| {
4685            leader.remove_excerpts([], cx);
4686        });
4687        assert_eq!(
4688            leader_multibuffer.read(cx).snapshot(cx).text(),
4689            follower_multibuffer.read(cx).snapshot(cx).text(),
4690        );
4691        assert_eq!(*follower_edit_event_count.read(), 3);
4692
4693        // Adding an empty set of excerpts is a noop.
4694        leader_multibuffer.update(cx, |leader, cx| {
4695            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
4696        });
4697        assert_eq!(
4698            leader_multibuffer.read(cx).snapshot(cx).text(),
4699            follower_multibuffer.read(cx).snapshot(cx).text(),
4700        );
4701        assert_eq!(*follower_edit_event_count.read(), 3);
4702
4703        leader_multibuffer.update(cx, |leader, cx| {
4704            leader.clear(cx);
4705        });
4706        assert_eq!(
4707            leader_multibuffer.read(cx).snapshot(cx).text(),
4708            follower_multibuffer.read(cx).snapshot(cx).text(),
4709        );
4710        assert_eq!(*follower_edit_event_count.read(), 4);
4711    }
4712
4713    #[gpui::test]
4714    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
4715        let buffer = cx.new_model(|cx| {
4716            Buffer::new(
4717                0,
4718                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4719                sample_text(20, 3, 'a'),
4720            )
4721        });
4722        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4723        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
4724            multibuffer.push_excerpts_with_context_lines(
4725                buffer.clone(),
4726                vec![
4727                    Point::new(3, 2)..Point::new(4, 2),
4728                    Point::new(7, 1)..Point::new(7, 3),
4729                    Point::new(15, 0)..Point::new(15, 0),
4730                ],
4731                2,
4732                cx,
4733            )
4734        });
4735
4736        let snapshot = multibuffer.read(cx).snapshot(cx);
4737        assert_eq!(
4738            snapshot.text(),
4739            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4740        );
4741
4742        assert_eq!(
4743            anchor_ranges
4744                .iter()
4745                .map(|range| range.to_point(&snapshot))
4746                .collect::<Vec<_>>(),
4747            vec![
4748                Point::new(2, 2)..Point::new(3, 2),
4749                Point::new(6, 1)..Point::new(6, 3),
4750                Point::new(12, 0)..Point::new(12, 0)
4751            ]
4752        );
4753    }
4754
4755    #[gpui::test]
4756    async fn test_stream_excerpts_with_context_lines(cx: &mut TestAppContext) {
4757        let buffer = cx.new_model(|cx| {
4758            Buffer::new(
4759                0,
4760                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4761                sample_text(20, 3, 'a'),
4762            )
4763        });
4764        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4765        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
4766            let snapshot = buffer.read(cx);
4767            let ranges = vec![
4768                snapshot.anchor_before(Point::new(3, 2))..snapshot.anchor_before(Point::new(4, 2)),
4769                snapshot.anchor_before(Point::new(7, 1))..snapshot.anchor_before(Point::new(7, 3)),
4770                snapshot.anchor_before(Point::new(15, 0))
4771                    ..snapshot.anchor_before(Point::new(15, 0)),
4772            ];
4773            multibuffer.stream_excerpts_with_context_lines(buffer.clone(), ranges, 2, cx)
4774        });
4775
4776        let anchor_ranges = anchor_ranges.collect::<Vec<_>>().await;
4777
4778        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
4779        assert_eq!(
4780            snapshot.text(),
4781            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
4782        );
4783
4784        assert_eq!(
4785            anchor_ranges
4786                .iter()
4787                .map(|range| range.to_point(&snapshot))
4788                .collect::<Vec<_>>(),
4789            vec![
4790                Point::new(2, 2)..Point::new(3, 2),
4791                Point::new(6, 1)..Point::new(6, 3),
4792                Point::new(12, 0)..Point::new(12, 0)
4793            ]
4794        );
4795    }
4796
4797    #[gpui::test]
4798    fn test_empty_multibuffer(cx: &mut AppContext) {
4799        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4800
4801        let snapshot = multibuffer.read(cx).snapshot(cx);
4802        assert_eq!(snapshot.text(), "");
4803        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
4804        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
4805    }
4806
4807    #[gpui::test]
4808    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
4809        let buffer = cx.new_model(|cx| {
4810            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4811        });
4812        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4813        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4814        buffer.update(cx, |buffer, cx| {
4815            buffer.edit([(0..0, "X")], None, cx);
4816            buffer.edit([(5..5, "Y")], None, cx);
4817        });
4818        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4819
4820        assert_eq!(old_snapshot.text(), "abcd");
4821        assert_eq!(new_snapshot.text(), "XabcdY");
4822
4823        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4824        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4825        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
4826        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
4827    }
4828
4829    #[gpui::test]
4830    fn test_multibuffer_anchors(cx: &mut AppContext) {
4831        let buffer_1 = cx.new_model(|cx| {
4832            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4833        });
4834        let buffer_2 = cx.new_model(|cx| {
4835            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "efghi")
4836        });
4837        let multibuffer = cx.new_model(|cx| {
4838            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
4839            multibuffer.push_excerpts(
4840                buffer_1.clone(),
4841                [ExcerptRange {
4842                    context: 0..4,
4843                    primary: None,
4844                }],
4845                cx,
4846            );
4847            multibuffer.push_excerpts(
4848                buffer_2.clone(),
4849                [ExcerptRange {
4850                    context: 0..5,
4851                    primary: None,
4852                }],
4853                cx,
4854            );
4855            multibuffer
4856        });
4857        let old_snapshot = multibuffer.read(cx).snapshot(cx);
4858
4859        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
4860        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
4861        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4862        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
4863        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4864        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
4865
4866        buffer_1.update(cx, |buffer, cx| {
4867            buffer.edit([(0..0, "W")], None, cx);
4868            buffer.edit([(5..5, "X")], None, cx);
4869        });
4870        buffer_2.update(cx, |buffer, cx| {
4871            buffer.edit([(0..0, "Y")], None, cx);
4872            buffer.edit([(6..6, "Z")], None, cx);
4873        });
4874        let new_snapshot = multibuffer.read(cx).snapshot(cx);
4875
4876        assert_eq!(old_snapshot.text(), "abcd\nefghi");
4877        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
4878
4879        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
4880        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
4881        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
4882        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
4883        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
4884        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
4885        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
4886        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
4887        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
4888        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
4889    }
4890
4891    #[gpui::test]
4892    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
4893        let buffer_1 = cx.new_model(|cx| {
4894            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "abcd")
4895        });
4896        let buffer_2 = cx.new_model(|cx| {
4897            Buffer::new(
4898                0,
4899                BufferId::new(cx.entity_id().as_u64()).unwrap(),
4900                "ABCDEFGHIJKLMNOP",
4901            )
4902        });
4903        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4904
4905        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
4906        // Add an excerpt from buffer 1 that spans this new insertion.
4907        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
4908        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
4909            multibuffer
4910                .push_excerpts(
4911                    buffer_1.clone(),
4912                    [ExcerptRange {
4913                        context: 0..7,
4914                        primary: None,
4915                    }],
4916                    cx,
4917                )
4918                .pop()
4919                .unwrap()
4920        });
4921
4922        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
4923        assert_eq!(snapshot_1.text(), "abcd123");
4924
4925        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
4926        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
4927            multibuffer.remove_excerpts([excerpt_id_1], cx);
4928            let mut ids = multibuffer
4929                .push_excerpts(
4930                    buffer_2.clone(),
4931                    [
4932                        ExcerptRange {
4933                            context: 0..4,
4934                            primary: None,
4935                        },
4936                        ExcerptRange {
4937                            context: 6..10,
4938                            primary: None,
4939                        },
4940                        ExcerptRange {
4941                            context: 12..16,
4942                            primary: None,
4943                        },
4944                    ],
4945                    cx,
4946                )
4947                .into_iter();
4948            (ids.next().unwrap(), ids.next().unwrap())
4949        });
4950        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
4951        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
4952
4953        // The old excerpt id doesn't get reused.
4954        assert_ne!(excerpt_id_2, excerpt_id_1);
4955
4956        // Resolve some anchors from the previous snapshot in the new snapshot.
4957        // The current excerpts are from a different buffer, so we don't attempt to
4958        // resolve the old text anchor in the new buffer.
4959        assert_eq!(
4960            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
4961            0
4962        );
4963        assert_eq!(
4964            snapshot_2.summaries_for_anchors::<usize, _>(&[
4965                snapshot_1.anchor_before(2),
4966                snapshot_1.anchor_after(3)
4967            ]),
4968            vec![0, 0]
4969        );
4970
4971        // Refresh anchors from the old snapshot. The return value indicates that both
4972        // anchors lost their original excerpt.
4973        let refresh =
4974            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
4975        assert_eq!(
4976            refresh,
4977            &[
4978                (0, snapshot_2.anchor_before(0), false),
4979                (1, snapshot_2.anchor_after(0), false),
4980            ]
4981        );
4982
4983        // Replace the middle excerpt with a smaller excerpt in buffer 2,
4984        // that intersects the old excerpt.
4985        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
4986            multibuffer.remove_excerpts([excerpt_id_3], cx);
4987            multibuffer
4988                .insert_excerpts_after(
4989                    excerpt_id_2,
4990                    buffer_2.clone(),
4991                    [ExcerptRange {
4992                        context: 5..8,
4993                        primary: None,
4994                    }],
4995                    cx,
4996                )
4997                .pop()
4998                .unwrap()
4999        });
5000
5001        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
5002        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
5003        assert_ne!(excerpt_id_5, excerpt_id_3);
5004
5005        // Resolve some anchors from the previous snapshot in the new snapshot.
5006        // The third anchor can't be resolved, since its excerpt has been removed,
5007        // so it resolves to the same position as its predecessor.
5008        let anchors = [
5009            snapshot_2.anchor_before(0),
5010            snapshot_2.anchor_after(2),
5011            snapshot_2.anchor_after(6),
5012            snapshot_2.anchor_after(14),
5013        ];
5014        assert_eq!(
5015            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
5016            &[0, 2, 9, 13]
5017        );
5018
5019        let new_anchors = snapshot_3.refresh_anchors(&anchors);
5020        assert_eq!(
5021            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
5022            &[(0, true), (1, true), (2, true), (3, true)]
5023        );
5024        assert_eq!(
5025            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
5026            &[0, 2, 7, 13]
5027        );
5028    }
5029
5030    #[gpui::test(iterations = 100)]
5031    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
5032        let operations = env::var("OPERATIONS")
5033            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
5034            .unwrap_or(10);
5035
5036        let mut buffers: Vec<Model<Buffer>> = Vec::new();
5037        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5038        let mut excerpt_ids = Vec::<ExcerptId>::new();
5039        let mut expected_excerpts = Vec::<(Model<Buffer>, Range<text::Anchor>)>::new();
5040        let mut anchors = Vec::new();
5041        let mut old_versions = Vec::new();
5042
5043        for _ in 0..operations {
5044            match rng.gen_range(0..100) {
5045                0..=19 if !buffers.is_empty() => {
5046                    let buffer = buffers.choose(&mut rng).unwrap();
5047                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
5048                }
5049                20..=29 if !expected_excerpts.is_empty() => {
5050                    let mut ids_to_remove = vec![];
5051                    for _ in 0..rng.gen_range(1..=3) {
5052                        if expected_excerpts.is_empty() {
5053                            break;
5054                        }
5055
5056                        let ix = rng.gen_range(0..expected_excerpts.len());
5057                        ids_to_remove.push(excerpt_ids.remove(ix));
5058                        let (buffer, range) = expected_excerpts.remove(ix);
5059                        let buffer = buffer.read(cx);
5060                        log::info!(
5061                            "Removing excerpt {}: {:?}",
5062                            ix,
5063                            buffer
5064                                .text_for_range(range.to_offset(buffer))
5065                                .collect::<String>(),
5066                        );
5067                    }
5068                    let snapshot = multibuffer.read(cx).read(cx);
5069                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(&b, &snapshot));
5070                    drop(snapshot);
5071                    multibuffer.update(cx, |multibuffer, cx| {
5072                        multibuffer.remove_excerpts(ids_to_remove, cx)
5073                    });
5074                }
5075                30..=39 if !expected_excerpts.is_empty() => {
5076                    let multibuffer = multibuffer.read(cx).read(cx);
5077                    let offset =
5078                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
5079                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
5080                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
5081                    anchors.push(multibuffer.anchor_at(offset, bias));
5082                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
5083                }
5084                40..=44 if !anchors.is_empty() => {
5085                    let multibuffer = multibuffer.read(cx).read(cx);
5086                    let prev_len = anchors.len();
5087                    anchors = multibuffer
5088                        .refresh_anchors(&anchors)
5089                        .into_iter()
5090                        .map(|a| a.1)
5091                        .collect();
5092
5093                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
5094                    // overshoot its boundaries.
5095                    assert_eq!(anchors.len(), prev_len);
5096                    for anchor in &anchors {
5097                        if anchor.excerpt_id == ExcerptId::min()
5098                            || anchor.excerpt_id == ExcerptId::max()
5099                        {
5100                            continue;
5101                        }
5102
5103                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
5104                        assert_eq!(excerpt.id, anchor.excerpt_id);
5105                        assert!(excerpt.contains(anchor));
5106                    }
5107                }
5108                _ => {
5109                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
5110                        let base_text = util::RandomCharIter::new(&mut rng)
5111                            .take(10)
5112                            .collect::<String>();
5113                        buffers.push(cx.new_model(|cx| {
5114                            Buffer::new(
5115                                0,
5116                                BufferId::new(cx.entity_id().as_u64()).unwrap(),
5117                                base_text,
5118                            )
5119                        }));
5120                        buffers.last().unwrap()
5121                    } else {
5122                        buffers.choose(&mut rng).unwrap()
5123                    };
5124
5125                    let buffer = buffer_handle.read(cx);
5126                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
5127                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5128                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
5129                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
5130                    let prev_excerpt_id = excerpt_ids
5131                        .get(prev_excerpt_ix)
5132                        .cloned()
5133                        .unwrap_or_else(ExcerptId::max);
5134                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
5135
5136                    log::info!(
5137                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
5138                        excerpt_ix,
5139                        expected_excerpts.len(),
5140                        buffer_handle.read(cx).remote_id(),
5141                        buffer.text(),
5142                        start_ix..end_ix,
5143                        &buffer.text()[start_ix..end_ix]
5144                    );
5145
5146                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
5147                        multibuffer
5148                            .insert_excerpts_after(
5149                                prev_excerpt_id,
5150                                buffer_handle.clone(),
5151                                [ExcerptRange {
5152                                    context: start_ix..end_ix,
5153                                    primary: None,
5154                                }],
5155                                cx,
5156                            )
5157                            .pop()
5158                            .unwrap()
5159                    });
5160
5161                    excerpt_ids.insert(excerpt_ix, excerpt_id);
5162                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
5163                }
5164            }
5165
5166            if rng.gen_bool(0.3) {
5167                multibuffer.update(cx, |multibuffer, cx| {
5168                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
5169                })
5170            }
5171
5172            let snapshot = multibuffer.read(cx).snapshot(cx);
5173
5174            let mut excerpt_starts = Vec::new();
5175            let mut expected_text = String::new();
5176            let mut expected_buffer_rows = Vec::new();
5177            for (buffer, range) in &expected_excerpts {
5178                let buffer = buffer.read(cx);
5179                let buffer_range = range.to_offset(buffer);
5180
5181                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
5182                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
5183                expected_text.push('\n');
5184
5185                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
5186                    ..=buffer.offset_to_point(buffer_range.end).row;
5187                for row in buffer_row_range {
5188                    expected_buffer_rows.push(Some(row));
5189                }
5190            }
5191            // Remove final trailing newline.
5192            if !expected_excerpts.is_empty() {
5193                expected_text.pop();
5194            }
5195
5196            // Always report one buffer row
5197            if expected_buffer_rows.is_empty() {
5198                expected_buffer_rows.push(Some(0));
5199            }
5200
5201            assert_eq!(snapshot.text(), expected_text);
5202            log::info!("MultiBuffer text: {:?}", expected_text);
5203
5204            assert_eq!(
5205                snapshot.buffer_rows(0).collect::<Vec<_>>(),
5206                expected_buffer_rows,
5207            );
5208
5209            for _ in 0..5 {
5210                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
5211                assert_eq!(
5212                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
5213                    &expected_buffer_rows[start_row..],
5214                    "buffer_rows({})",
5215                    start_row
5216                );
5217            }
5218
5219            assert_eq!(
5220                snapshot.max_buffer_row(),
5221                expected_buffer_rows.into_iter().flatten().max().unwrap()
5222            );
5223
5224            let mut excerpt_starts = excerpt_starts.into_iter();
5225            for (buffer, range) in &expected_excerpts {
5226                let buffer = buffer.read(cx);
5227                let buffer_id = buffer.remote_id();
5228                let buffer_range = range.to_offset(buffer);
5229                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
5230                let buffer_start_point_utf16 =
5231                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
5232
5233                let excerpt_start = excerpt_starts.next().unwrap();
5234                let mut offset = excerpt_start.len;
5235                let mut buffer_offset = buffer_range.start;
5236                let mut point = excerpt_start.lines;
5237                let mut buffer_point = buffer_start_point;
5238                let mut point_utf16 = excerpt_start.lines_utf16();
5239                let mut buffer_point_utf16 = buffer_start_point_utf16;
5240                for ch in buffer
5241                    .snapshot()
5242                    .chunks(buffer_range.clone(), false)
5243                    .flat_map(|c| c.text.chars())
5244                {
5245                    for _ in 0..ch.len_utf8() {
5246                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
5247                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
5248                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
5249                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
5250                        assert_eq!(
5251                            left_offset,
5252                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
5253                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
5254                            offset,
5255                            buffer_id,
5256                            buffer_offset,
5257                        );
5258                        assert_eq!(
5259                            right_offset,
5260                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
5261                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
5262                            offset,
5263                            buffer_id,
5264                            buffer_offset,
5265                        );
5266
5267                        let left_point = snapshot.clip_point(point, Bias::Left);
5268                        let right_point = snapshot.clip_point(point, Bias::Right);
5269                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
5270                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
5271                        assert_eq!(
5272                            left_point,
5273                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
5274                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
5275                            point,
5276                            buffer_id,
5277                            buffer_point,
5278                        );
5279                        assert_eq!(
5280                            right_point,
5281                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
5282                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
5283                            point,
5284                            buffer_id,
5285                            buffer_point,
5286                        );
5287
5288                        assert_eq!(
5289                            snapshot.point_to_offset(left_point),
5290                            left_offset,
5291                            "point_to_offset({:?})",
5292                            left_point,
5293                        );
5294                        assert_eq!(
5295                            snapshot.offset_to_point(left_offset),
5296                            left_point,
5297                            "offset_to_point({:?})",
5298                            left_offset,
5299                        );
5300
5301                        offset += 1;
5302                        buffer_offset += 1;
5303                        if ch == '\n' {
5304                            point += Point::new(1, 0);
5305                            buffer_point += Point::new(1, 0);
5306                        } else {
5307                            point += Point::new(0, 1);
5308                            buffer_point += Point::new(0, 1);
5309                        }
5310                    }
5311
5312                    for _ in 0..ch.len_utf16() {
5313                        let left_point_utf16 =
5314                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
5315                        let right_point_utf16 =
5316                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
5317                        let buffer_left_point_utf16 =
5318                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
5319                        let buffer_right_point_utf16 =
5320                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
5321                        assert_eq!(
5322                            left_point_utf16,
5323                            excerpt_start.lines_utf16()
5324                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
5325                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
5326                            point_utf16,
5327                            buffer_id,
5328                            buffer_point_utf16,
5329                        );
5330                        assert_eq!(
5331                            right_point_utf16,
5332                            excerpt_start.lines_utf16()
5333                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
5334                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
5335                            point_utf16,
5336                            buffer_id,
5337                            buffer_point_utf16,
5338                        );
5339
5340                        if ch == '\n' {
5341                            point_utf16 += PointUtf16::new(1, 0);
5342                            buffer_point_utf16 += PointUtf16::new(1, 0);
5343                        } else {
5344                            point_utf16 += PointUtf16::new(0, 1);
5345                            buffer_point_utf16 += PointUtf16::new(0, 1);
5346                        }
5347                    }
5348                }
5349            }
5350
5351            for (row, line) in expected_text.split('\n').enumerate() {
5352                assert_eq!(
5353                    snapshot.line_len(row as u32),
5354                    line.len() as u32,
5355                    "line_len({}).",
5356                    row
5357                );
5358            }
5359
5360            let text_rope = Rope::from(expected_text.as_str());
5361            for _ in 0..10 {
5362                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5363                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5364
5365                let text_for_range = snapshot
5366                    .text_for_range(start_ix..end_ix)
5367                    .collect::<String>();
5368                assert_eq!(
5369                    text_for_range,
5370                    &expected_text[start_ix..end_ix],
5371                    "incorrect text for range {:?}",
5372                    start_ix..end_ix
5373                );
5374
5375                let excerpted_buffer_ranges = multibuffer
5376                    .read(cx)
5377                    .range_to_buffer_ranges(start_ix..end_ix, cx);
5378                let excerpted_buffers_text = excerpted_buffer_ranges
5379                    .iter()
5380                    .map(|(buffer, buffer_range, _)| {
5381                        buffer
5382                            .read(cx)
5383                            .text_for_range(buffer_range.clone())
5384                            .collect::<String>()
5385                    })
5386                    .collect::<Vec<_>>()
5387                    .join("\n");
5388                assert_eq!(excerpted_buffers_text, text_for_range);
5389                if !expected_excerpts.is_empty() {
5390                    assert!(!excerpted_buffer_ranges.is_empty());
5391                }
5392
5393                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
5394                assert_eq!(
5395                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
5396                    expected_summary,
5397                    "incorrect summary for range {:?}",
5398                    start_ix..end_ix
5399                );
5400            }
5401
5402            // Anchor resolution
5403            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
5404            assert_eq!(anchors.len(), summaries.len());
5405            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
5406                assert!(resolved_offset <= snapshot.len());
5407                assert_eq!(
5408                    snapshot.summary_for_anchor::<usize>(anchor),
5409                    resolved_offset
5410                );
5411            }
5412
5413            for _ in 0..10 {
5414                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5415                assert_eq!(
5416                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
5417                    expected_text[..end_ix].chars().rev().collect::<String>(),
5418                );
5419            }
5420
5421            for _ in 0..10 {
5422                let end_ix = rng.gen_range(0..=text_rope.len());
5423                let start_ix = rng.gen_range(0..=end_ix);
5424                assert_eq!(
5425                    snapshot
5426                        .bytes_in_range(start_ix..end_ix)
5427                        .flatten()
5428                        .copied()
5429                        .collect::<Vec<_>>(),
5430                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
5431                    "bytes_in_range({:?})",
5432                    start_ix..end_ix,
5433                );
5434            }
5435        }
5436
5437        let snapshot = multibuffer.read(cx).snapshot(cx);
5438        for (old_snapshot, subscription) in old_versions {
5439            let edits = subscription.consume().into_inner();
5440
5441            log::info!(
5442                "applying subscription edits to old text: {:?}: {:?}",
5443                old_snapshot.text(),
5444                edits,
5445            );
5446
5447            let mut text = old_snapshot.text();
5448            for edit in edits {
5449                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
5450                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
5451            }
5452            assert_eq!(text.to_string(), snapshot.text());
5453        }
5454    }
5455
5456    #[gpui::test]
5457    fn test_history(cx: &mut AppContext) {
5458        let test_settings = SettingsStore::test(cx);
5459        cx.set_global(test_settings);
5460
5461        let buffer_1 = cx.new_model(|cx| {
5462            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "1234")
5463        });
5464        let buffer_2 = cx.new_model(|cx| {
5465            Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), "5678")
5466        });
5467        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5468        let group_interval = multibuffer.read(cx).history.group_interval;
5469        multibuffer.update(cx, |multibuffer, cx| {
5470            multibuffer.push_excerpts(
5471                buffer_1.clone(),
5472                [ExcerptRange {
5473                    context: 0..buffer_1.read(cx).len(),
5474                    primary: None,
5475                }],
5476                cx,
5477            );
5478            multibuffer.push_excerpts(
5479                buffer_2.clone(),
5480                [ExcerptRange {
5481                    context: 0..buffer_2.read(cx).len(),
5482                    primary: None,
5483                }],
5484                cx,
5485            );
5486        });
5487
5488        let mut now = Instant::now();
5489
5490        multibuffer.update(cx, |multibuffer, cx| {
5491            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
5492            multibuffer.edit(
5493                [
5494                    (Point::new(0, 0)..Point::new(0, 0), "A"),
5495                    (Point::new(1, 0)..Point::new(1, 0), "A"),
5496                ],
5497                None,
5498                cx,
5499            );
5500            multibuffer.edit(
5501                [
5502                    (Point::new(0, 1)..Point::new(0, 1), "B"),
5503                    (Point::new(1, 1)..Point::new(1, 1), "B"),
5504                ],
5505                None,
5506                cx,
5507            );
5508            multibuffer.end_transaction_at(now, cx);
5509            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5510
5511            // Edit buffer 1 through the multibuffer
5512            now += 2 * group_interval;
5513            multibuffer.start_transaction_at(now, cx);
5514            multibuffer.edit([(2..2, "C")], None, cx);
5515            multibuffer.end_transaction_at(now, cx);
5516            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
5517
5518            // Edit buffer 1 independently
5519            buffer_1.update(cx, |buffer_1, cx| {
5520                buffer_1.start_transaction_at(now);
5521                buffer_1.edit([(3..3, "D")], None, cx);
5522                buffer_1.end_transaction_at(now, cx);
5523
5524                now += 2 * group_interval;
5525                buffer_1.start_transaction_at(now);
5526                buffer_1.edit([(4..4, "E")], None, cx);
5527                buffer_1.end_transaction_at(now, cx);
5528            });
5529            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5530
5531            // An undo in the multibuffer undoes the multibuffer transaction
5532            // and also any individual buffer edits that have occurred since
5533            // that transaction.
5534            multibuffer.undo(cx);
5535            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5536
5537            multibuffer.undo(cx);
5538            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5539
5540            multibuffer.redo(cx);
5541            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5542
5543            multibuffer.redo(cx);
5544            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5545
5546            // Undo buffer 2 independently.
5547            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
5548            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
5549
5550            // An undo in the multibuffer undoes the components of the
5551            // the last multibuffer transaction that are not already undone.
5552            multibuffer.undo(cx);
5553            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
5554
5555            multibuffer.undo(cx);
5556            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5557
5558            multibuffer.redo(cx);
5559            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5560
5561            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
5562            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5563
5564            // Redo stack gets cleared after an edit.
5565            now += 2 * group_interval;
5566            multibuffer.start_transaction_at(now, cx);
5567            multibuffer.edit([(0..0, "X")], None, cx);
5568            multibuffer.end_transaction_at(now, cx);
5569            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5570            multibuffer.redo(cx);
5571            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5572            multibuffer.undo(cx);
5573            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5574            multibuffer.undo(cx);
5575            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5576
5577            // Transactions can be grouped manually.
5578            multibuffer.redo(cx);
5579            multibuffer.redo(cx);
5580            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5581            multibuffer.group_until_transaction(transaction_1, cx);
5582            multibuffer.undo(cx);
5583            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5584            multibuffer.redo(cx);
5585            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5586        });
5587    }
5588}