multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt, Offset};
   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};
  10use itertools::Itertools;
  11use language::{
  12    char_kind,
  13    language_settings::{language_settings, LanguageSettings},
  14    AutoindentMode, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability, CharKind, Chunk,
  15    CursorShape, DiagnosticEntry, File, IndentSize, Language, LanguageScope, OffsetRangeExt,
  16    OffsetUtf16, Outline, OutlineItem, Point, PointUtf16, Selection, TextDimension, ToOffset as _,
  17    ToOffsetUtf16 as _, ToPoint as _, ToPointUtf16 as _, TransactionId, Unclipped,
  18};
  19use smallvec::SmallVec;
  20use std::{
  21    borrow::Cow,
  22    cell::{Ref, RefCell},
  23    cmp, fmt,
  24    future::Future,
  25    io,
  26    iter::{self, FromIterator},
  27    mem,
  28    ops::{Range, RangeBounds, Sub},
  29    str,
  30    sync::Arc,
  31    time::{Duration, Instant},
  32};
  33use sum_tree::{Bias, Cursor, SumTree};
  34use text::{
  35    locator::Locator,
  36    subscription::{Subscription, Topic},
  37    BufferId, Edit, TextSummary,
  38};
  39use theme::SyntaxTheme;
  40
  41use util::post_inc;
  42
  43#[cfg(any(test, feature = "test-support"))]
  44use gpui::Context;
  45
  46const NEWLINES: &[u8] = &[b'\n'; u8::MAX as usize];
  47
  48#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  49pub struct ExcerptId(usize);
  50
  51/// One or more [`Buffers`](Buffer) being edited in a single view.
  52///
  53/// See <https://zed.dev/features#multi-buffers>
  54pub struct MultiBuffer {
  55    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  56    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  57    snapshot: RefCell<MultiBufferSnapshot>,
  58    /// Contains the state of the buffers being edited
  59    buffers: RefCell<HashMap<BufferId, BufferState>>,
  60    subscriptions: Topic,
  61    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  62    singleton: bool,
  63    replica_id: ReplicaId,
  64    history: History,
  65    title: Option<String>,
  66    capability: Capability,
  67}
  68
  69#[derive(Clone, Debug, PartialEq, Eq)]
  70pub enum Event {
  71    ExcerptsAdded {
  72        buffer: Model<Buffer>,
  73        predecessor: ExcerptId,
  74        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
  75    },
  76    ExcerptsRemoved {
  77        ids: Vec<ExcerptId>,
  78    },
  79    ExcerptsEdited {
  80        ids: Vec<ExcerptId>,
  81    },
  82    Edited {
  83        singleton_buffer_edited: bool,
  84    },
  85    TransactionUndone {
  86        transaction_id: TransactionId,
  87    },
  88    Reloaded,
  89    DiffBaseChanged,
  90    DiffUpdated {
  91        buffer: Model<Buffer>,
  92    },
  93    LanguageChanged,
  94    CapabilityChanged,
  95    Reparsed,
  96    Saved,
  97    FileHandleChanged,
  98    Closed,
  99    DirtyChanged,
 100    DiagnosticsUpdated,
 101}
 102
 103pub type MultiBufferPoint = Point;
 104
 105#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, serde::Deserialize)]
 106#[serde(transparent)]
 107pub struct MultiBufferRow(pub u32);
 108
 109impl MultiBufferRow {
 110    pub const MIN: Self = Self(0);
 111    pub const MAX: Self = Self(u32::MAX);
 112}
 113#[derive(Clone)]
 114struct History {
 115    next_transaction_id: TransactionId,
 116    undo_stack: Vec<Transaction>,
 117    redo_stack: Vec<Transaction>,
 118    transaction_depth: usize,
 119    group_interval: Duration,
 120}
 121
 122#[derive(Clone)]
 123struct Transaction {
 124    id: TransactionId,
 125    buffer_transactions: HashMap<BufferId, text::TransactionId>,
 126    first_edit_at: Instant,
 127    last_edit_at: Instant,
 128    suppress_grouping: bool,
 129}
 130
 131pub trait ToOffset: 'static + fmt::Debug {
 132    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
 133}
 134
 135pub trait ToOffsetUtf16: 'static + fmt::Debug {
 136    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16;
 137}
 138
 139pub trait ToPoint: 'static + fmt::Debug {
 140    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 141}
 142
 143pub trait ToPointUtf16: 'static + fmt::Debug {
 144    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 145}
 146
 147struct BufferState {
 148    buffer: Model<Buffer>,
 149    last_version: clock::Global,
 150    last_parse_count: usize,
 151    last_selections_update_count: usize,
 152    last_diagnostics_update_count: usize,
 153    last_file_update_count: usize,
 154    last_git_diff_update_count: usize,
 155    excerpts: Vec<Locator>,
 156    _subscriptions: [gpui::Subscription; 2],
 157}
 158
 159/// The contents of a [`MultiBuffer`] at a single point in time.
 160#[derive(Clone, Default)]
 161pub struct MultiBufferSnapshot {
 162    singleton: bool,
 163    excerpts: SumTree<Excerpt>,
 164    excerpt_ids: SumTree<ExcerptIdMapping>,
 165    parse_count: usize,
 166    diagnostics_update_count: usize,
 167    trailing_excerpt_update_count: usize,
 168    git_diff_update_count: usize,
 169    edit_count: usize,
 170    is_dirty: bool,
 171    has_conflict: bool,
 172    show_headers: bool,
 173}
 174
 175/// A boundary between [`Excerpt`]s in a [`MultiBuffer`]
 176pub struct ExcerptBoundary {
 177    pub id: ExcerptId,
 178    pub row: MultiBufferRow,
 179    pub buffer: BufferSnapshot,
 180    pub range: ExcerptRange<text::Anchor>,
 181    /// It's possible to have multiple excerpts in the same buffer,
 182    /// and they are rendered together without a new File header.
 183    ///
 184    /// This flag indicates that the excerpt is the first one in the buffer.
 185    pub starts_new_buffer: bool,
 186}
 187
 188/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 189#[derive(Clone)]
 190struct Excerpt {
 191    /// The unique identifier for this excerpt
 192    id: ExcerptId,
 193    /// The location of the excerpt in the [`MultiBuffer`]
 194    locator: Locator,
 195    /// The buffer being excerpted
 196    buffer_id: BufferId,
 197    /// A snapshot of the buffer being excerpted
 198    buffer: BufferSnapshot,
 199    /// The range of the buffer to be shown in the excerpt
 200    range: ExcerptRange<text::Anchor>,
 201    /// The last row in the excerpted slice of the buffer
 202    max_buffer_row: BufferRow,
 203    /// A summary of the text in the excerpt
 204    text_summary: TextSummary,
 205    has_trailing_newline: bool,
 206}
 207
 208/// A public view into an [`Excerpt`] in a [`MultiBuffer`].
 209///
 210/// Contains methods for getting the [`Buffer`] of the excerpt,
 211/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 212#[derive(Clone)]
 213pub struct MultiBufferExcerpt<'a> {
 214    excerpt: &'a Excerpt,
 215    excerpt_offset: usize,
 216}
 217
 218#[derive(Clone, Debug)]
 219struct ExcerptIdMapping {
 220    id: ExcerptId,
 221    locator: Locator,
 222}
 223
 224/// A range of text from a single [`Buffer`], to be shown as an [`Excerpt`].
 225/// These ranges are relative to the buffer itself
 226#[derive(Clone, Debug, Eq, PartialEq)]
 227pub struct ExcerptRange<T> {
 228    /// The full range of text to be shown in the excerpt.
 229    pub context: Range<T>,
 230    /// The primary range of text to be highlighted in the excerpt.
 231    /// In a multi-buffer search, this would be the text that matched the search
 232    pub primary: Option<Range<T>>,
 233}
 234
 235#[derive(Clone, Debug, Default)]
 236struct ExcerptSummary {
 237    excerpt_id: ExcerptId,
 238    /// The location of the last [`Excerpt`] being summarized
 239    excerpt_locator: Locator,
 240    /// The maximum row of the [`Excerpt`]s being summarized
 241    max_buffer_row: MultiBufferRow,
 242    text: TextSummary,
 243}
 244
 245#[derive(Clone)]
 246pub struct MultiBufferRows<'a> {
 247    buffer_row_range: Range<u32>,
 248    excerpts: Cursor<'a, Excerpt, Point>,
 249}
 250
 251pub struct MultiBufferChunks<'a> {
 252    range: Range<usize>,
 253    excerpts: Cursor<'a, Excerpt, usize>,
 254    excerpt_chunks: Option<ExcerptChunks<'a>>,
 255    language_aware: bool,
 256}
 257
 258pub struct MultiBufferBytes<'a> {
 259    range: Range<usize>,
 260    excerpts: Cursor<'a, Excerpt, usize>,
 261    excerpt_bytes: Option<ExcerptBytes<'a>>,
 262    chunk: &'a [u8],
 263}
 264
 265pub struct ReversedMultiBufferBytes<'a> {
 266    range: Range<usize>,
 267    excerpts: Cursor<'a, Excerpt, usize>,
 268    excerpt_bytes: Option<ExcerptBytes<'a>>,
 269    chunk: &'a [u8],
 270}
 271
 272struct ExcerptChunks<'a> {
 273    content_chunks: BufferChunks<'a>,
 274    footer_height: usize,
 275}
 276
 277struct ExcerptBytes<'a> {
 278    content_bytes: text::Bytes<'a>,
 279    padding_height: usize,
 280    reversed: bool,
 281}
 282
 283impl MultiBuffer {
 284    pub fn new(replica_id: ReplicaId, capability: Capability) -> Self {
 285        Self {
 286            snapshot: RefCell::new(MultiBufferSnapshot {
 287                show_headers: true,
 288                ..MultiBufferSnapshot::default()
 289            }),
 290            buffers: RefCell::default(),
 291            subscriptions: Topic::default(),
 292            singleton: false,
 293            capability,
 294            replica_id,
 295            title: None,
 296            history: History {
 297                next_transaction_id: clock::Lamport::default(),
 298                undo_stack: Vec::new(),
 299                redo_stack: Vec::new(),
 300                transaction_depth: 0,
 301                group_interval: Duration::from_millis(300),
 302            },
 303        }
 304    }
 305
 306    pub fn without_headers(replica_id: ReplicaId, capability: Capability) -> Self {
 307        Self {
 308            snapshot: Default::default(),
 309            buffers: Default::default(),
 310            subscriptions: Default::default(),
 311            singleton: false,
 312            capability,
 313            replica_id,
 314            history: History {
 315                next_transaction_id: Default::default(),
 316                undo_stack: Default::default(),
 317                redo_stack: Default::default(),
 318                transaction_depth: 0,
 319                group_interval: Duration::from_millis(300),
 320            },
 321            title: Default::default(),
 322        }
 323    }
 324
 325    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 326        let mut buffers = HashMap::default();
 327        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 328            buffers.insert(
 329                *buffer_id,
 330                BufferState {
 331                    buffer: buffer_state.buffer.clone(),
 332                    last_version: buffer_state.last_version.clone(),
 333                    last_parse_count: buffer_state.last_parse_count,
 334                    last_selections_update_count: buffer_state.last_selections_update_count,
 335                    last_diagnostics_update_count: buffer_state.last_diagnostics_update_count,
 336                    last_file_update_count: buffer_state.last_file_update_count,
 337                    last_git_diff_update_count: buffer_state.last_git_diff_update_count,
 338                    excerpts: buffer_state.excerpts.clone(),
 339                    _subscriptions: [
 340                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 341                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 342                    ],
 343                },
 344            );
 345        }
 346        Self {
 347            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 348            buffers: RefCell::new(buffers),
 349            subscriptions: Default::default(),
 350            singleton: self.singleton,
 351            capability: self.capability,
 352            replica_id: self.replica_id,
 353            history: self.history.clone(),
 354            title: self.title.clone(),
 355        }
 356    }
 357
 358    pub fn with_title(mut self, title: String) -> Self {
 359        self.title = Some(title);
 360        self
 361    }
 362
 363    pub fn read_only(&self) -> bool {
 364        self.capability == Capability::ReadOnly
 365    }
 366
 367    pub fn singleton(buffer: Model<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 368        let mut this = Self::new(buffer.read(cx).replica_id(), buffer.read(cx).capability());
 369        this.singleton = true;
 370        this.push_excerpts(
 371            buffer,
 372            [ExcerptRange {
 373                context: text::Anchor::MIN..text::Anchor::MAX,
 374                primary: None,
 375            }],
 376            cx,
 377        );
 378        this.snapshot.borrow_mut().singleton = true;
 379        this
 380    }
 381
 382    pub fn replica_id(&self) -> ReplicaId {
 383        self.replica_id
 384    }
 385
 386    /// Returns an up-to-date snapshot of the MultiBuffer.
 387    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 388        self.sync(cx);
 389        self.snapshot.borrow().clone()
 390    }
 391
 392    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 393        self.sync(cx);
 394        self.snapshot.borrow()
 395    }
 396
 397    pub fn as_singleton(&self) -> Option<Model<Buffer>> {
 398        if self.singleton {
 399            return Some(
 400                self.buffers
 401                    .borrow()
 402                    .values()
 403                    .next()
 404                    .unwrap()
 405                    .buffer
 406                    .clone(),
 407            );
 408        } else {
 409            None
 410        }
 411    }
 412
 413    pub fn is_singleton(&self) -> bool {
 414        self.singleton
 415    }
 416
 417    pub fn subscribe(&mut self) -> Subscription {
 418        self.subscriptions.subscribe()
 419    }
 420
 421    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 422        self.read(cx).is_dirty()
 423    }
 424
 425    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 426        self.read(cx).has_conflict()
 427    }
 428
 429    // The `is_empty` signature doesn't match what clippy expects
 430    #[allow(clippy::len_without_is_empty)]
 431    pub fn len(&self, cx: &AppContext) -> usize {
 432        self.read(cx).len()
 433    }
 434
 435    pub fn is_empty(&self, cx: &AppContext) -> bool {
 436        self.len(cx) != 0
 437    }
 438
 439    pub fn symbols_containing<T: ToOffset>(
 440        &self,
 441        offset: T,
 442        theme: Option<&SyntaxTheme>,
 443        cx: &AppContext,
 444    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
 445        self.read(cx).symbols_containing(offset, theme)
 446    }
 447
 448    pub fn edit<I, S, T>(
 449        &mut self,
 450        edits: I,
 451        mut autoindent_mode: Option<AutoindentMode>,
 452        cx: &mut ModelContext<Self>,
 453    ) where
 454        I: IntoIterator<Item = (Range<S>, T)>,
 455        S: ToOffset,
 456        T: Into<Arc<str>>,
 457    {
 458        if self.read_only() {
 459            return;
 460        }
 461        if self.buffers.borrow().is_empty() {
 462            return;
 463        }
 464
 465        let snapshot = self.read(cx);
 466        let edits = edits.into_iter().map(|(range, new_text)| {
 467            let mut range = range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot);
 468            if range.start > range.end {
 469                mem::swap(&mut range.start, &mut range.end);
 470            }
 471            (range, new_text)
 472        });
 473
 474        if let Some(buffer) = self.as_singleton() {
 475            return buffer.update(cx, |buffer, cx| {
 476                buffer.edit(edits, autoindent_mode, cx);
 477            });
 478        }
 479
 480        let original_indent_columns = match &mut autoindent_mode {
 481            Some(AutoindentMode::Block {
 482                original_indent_columns,
 483            }) => mem::take(original_indent_columns),
 484            _ => Default::default(),
 485        };
 486
 487        struct BufferEdit {
 488            range: Range<usize>,
 489            new_text: Arc<str>,
 490            is_insertion: bool,
 491            original_indent_column: u32,
 492        }
 493        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
 494        let mut edited_excerpt_ids = Vec::new();
 495        let mut cursor = snapshot.excerpts.cursor::<usize>();
 496        for (ix, (range, new_text)) in edits.enumerate() {
 497            let new_text: Arc<str> = new_text.into();
 498            let original_indent_column = original_indent_columns.get(ix).copied().unwrap_or(0);
 499            cursor.seek(&range.start, Bias::Right, &());
 500            if cursor.item().is_none() && range.start == *cursor.start() {
 501                cursor.prev(&());
 502            }
 503            let start_excerpt = cursor.item().expect("start offset out of bounds");
 504            let start_overshoot = range.start - cursor.start();
 505            let buffer_start = start_excerpt
 506                .range
 507                .context
 508                .start
 509                .to_offset(&start_excerpt.buffer)
 510                + start_overshoot;
 511            edited_excerpt_ids.push(start_excerpt.id);
 512
 513            cursor.seek(&range.end, Bias::Right, &());
 514            if cursor.item().is_none() && range.end == *cursor.start() {
 515                cursor.prev(&());
 516            }
 517            let end_excerpt = cursor.item().expect("end offset out of bounds");
 518            let end_overshoot = range.end - cursor.start();
 519            let buffer_end = end_excerpt
 520                .range
 521                .context
 522                .start
 523                .to_offset(&end_excerpt.buffer)
 524                + end_overshoot;
 525
 526            if start_excerpt.id == end_excerpt.id {
 527                buffer_edits
 528                    .entry(start_excerpt.buffer_id)
 529                    .or_insert(Vec::new())
 530                    .push(BufferEdit {
 531                        range: buffer_start..buffer_end,
 532                        new_text,
 533                        is_insertion: true,
 534                        original_indent_column,
 535                    });
 536            } else {
 537                edited_excerpt_ids.push(end_excerpt.id);
 538                let start_excerpt_range = buffer_start
 539                    ..start_excerpt
 540                        .range
 541                        .context
 542                        .end
 543                        .to_offset(&start_excerpt.buffer);
 544                let end_excerpt_range = end_excerpt
 545                    .range
 546                    .context
 547                    .start
 548                    .to_offset(&end_excerpt.buffer)
 549                    ..buffer_end;
 550                buffer_edits
 551                    .entry(start_excerpt.buffer_id)
 552                    .or_insert(Vec::new())
 553                    .push(BufferEdit {
 554                        range: start_excerpt_range,
 555                        new_text: new_text.clone(),
 556                        is_insertion: true,
 557                        original_indent_column,
 558                    });
 559                buffer_edits
 560                    .entry(end_excerpt.buffer_id)
 561                    .or_insert(Vec::new())
 562                    .push(BufferEdit {
 563                        range: end_excerpt_range,
 564                        new_text: new_text.clone(),
 565                        is_insertion: false,
 566                        original_indent_column,
 567                    });
 568
 569                cursor.seek(&range.start, Bias::Right, &());
 570                cursor.next(&());
 571                while let Some(excerpt) = cursor.item() {
 572                    if excerpt.id == end_excerpt.id {
 573                        break;
 574                    }
 575                    buffer_edits
 576                        .entry(excerpt.buffer_id)
 577                        .or_insert(Vec::new())
 578                        .push(BufferEdit {
 579                            range: excerpt.range.context.to_offset(&excerpt.buffer),
 580                            new_text: new_text.clone(),
 581                            is_insertion: false,
 582                            original_indent_column,
 583                        });
 584                    edited_excerpt_ids.push(excerpt.id);
 585                    cursor.next(&());
 586                }
 587            }
 588        }
 589
 590        drop(cursor);
 591        drop(snapshot);
 592        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
 593        fn tail(
 594            this: &mut MultiBuffer,
 595            buffer_edits: HashMap<BufferId, Vec<BufferEdit>>,
 596            autoindent_mode: Option<AutoindentMode>,
 597            edited_excerpt_ids: Vec<ExcerptId>,
 598            cx: &mut ModelContext<MultiBuffer>,
 599        ) {
 600            for (buffer_id, mut edits) in buffer_edits {
 601                edits.sort_unstable_by_key(|edit| edit.range.start);
 602                this.buffers.borrow()[&buffer_id]
 603                    .buffer
 604                    .update(cx, |buffer, cx| {
 605                        let mut edits = edits.into_iter().peekable();
 606                        let mut insertions = Vec::new();
 607                        let mut original_indent_columns = Vec::new();
 608                        let mut deletions = Vec::new();
 609                        let empty_str: Arc<str> = "".into();
 610                        while let Some(BufferEdit {
 611                            mut range,
 612                            new_text,
 613                            mut is_insertion,
 614                            original_indent_column,
 615                        }) = edits.next()
 616                        {
 617                            while let Some(BufferEdit {
 618                                range: next_range,
 619                                is_insertion: next_is_insertion,
 620                                ..
 621                            }) = edits.peek()
 622                            {
 623                                if range.end >= next_range.start {
 624                                    range.end = cmp::max(next_range.end, range.end);
 625                                    is_insertion |= *next_is_insertion;
 626                                    edits.next();
 627                                } else {
 628                                    break;
 629                                }
 630                            }
 631
 632                            if is_insertion {
 633                                original_indent_columns.push(original_indent_column);
 634                                insertions.push((
 635                                    buffer.anchor_before(range.start)
 636                                        ..buffer.anchor_before(range.end),
 637                                    new_text.clone(),
 638                                ));
 639                            } else if !range.is_empty() {
 640                                deletions.push((
 641                                    buffer.anchor_before(range.start)
 642                                        ..buffer.anchor_before(range.end),
 643                                    empty_str.clone(),
 644                                ));
 645                            }
 646                        }
 647
 648                        let deletion_autoindent_mode =
 649                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 650                                Some(AutoindentMode::Block {
 651                                    original_indent_columns: Default::default(),
 652                                })
 653                            } else {
 654                                None
 655                            };
 656                        let insertion_autoindent_mode =
 657                            if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
 658                                Some(AutoindentMode::Block {
 659                                    original_indent_columns,
 660                                })
 661                            } else {
 662                                None
 663                            };
 664
 665                        buffer.edit(deletions, deletion_autoindent_mode, cx);
 666                        buffer.edit(insertions, insertion_autoindent_mode, cx);
 667                    })
 668            }
 669
 670            cx.emit(Event::ExcerptsEdited {
 671                ids: edited_excerpt_ids,
 672            });
 673        }
 674        tail(self, buffer_edits, autoindent_mode, edited_excerpt_ids, cx);
 675    }
 676
 677    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 678        self.start_transaction_at(Instant::now(), cx)
 679    }
 680
 681    pub fn start_transaction_at(
 682        &mut self,
 683        now: Instant,
 684        cx: &mut ModelContext<Self>,
 685    ) -> Option<TransactionId> {
 686        if let Some(buffer) = self.as_singleton() {
 687            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 688        }
 689
 690        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 691            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 692        }
 693        self.history.start_transaction(now)
 694    }
 695
 696    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 697        self.end_transaction_at(Instant::now(), cx)
 698    }
 699
 700    pub fn end_transaction_at(
 701        &mut self,
 702        now: Instant,
 703        cx: &mut ModelContext<Self>,
 704    ) -> Option<TransactionId> {
 705        if let Some(buffer) = self.as_singleton() {
 706            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 707        }
 708
 709        let mut buffer_transactions = HashMap::default();
 710        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 711            if let Some(transaction_id) =
 712                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 713            {
 714                buffer_transactions.insert(buffer.read(cx).remote_id(), transaction_id);
 715            }
 716        }
 717
 718        if self.history.end_transaction(now, buffer_transactions) {
 719            let transaction_id = self.history.group().unwrap();
 720            Some(transaction_id)
 721        } else {
 722            None
 723        }
 724    }
 725
 726    pub fn merge_transactions(
 727        &mut self,
 728        transaction: TransactionId,
 729        destination: TransactionId,
 730        cx: &mut ModelContext<Self>,
 731    ) {
 732        if let Some(buffer) = self.as_singleton() {
 733            buffer.update(cx, |buffer, _| {
 734                buffer.merge_transactions(transaction, destination)
 735            });
 736        } else {
 737            if let Some(transaction) = self.history.forget(transaction) {
 738                if let Some(destination) = self.history.transaction_mut(destination) {
 739                    for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
 740                        if let Some(destination_buffer_transaction_id) =
 741                            destination.buffer_transactions.get(&buffer_id)
 742                        {
 743                            if let Some(state) = self.buffers.borrow().get(&buffer_id) {
 744                                state.buffer.update(cx, |buffer, _| {
 745                                    buffer.merge_transactions(
 746                                        buffer_transaction_id,
 747                                        *destination_buffer_transaction_id,
 748                                    )
 749                                });
 750                            }
 751                        } else {
 752                            destination
 753                                .buffer_transactions
 754                                .insert(buffer_id, buffer_transaction_id);
 755                        }
 756                    }
 757                }
 758            }
 759        }
 760    }
 761
 762    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 763        self.history.finalize_last_transaction();
 764        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 765            buffer.update(cx, |buffer, _| {
 766                buffer.finalize_last_transaction();
 767            });
 768        }
 769    }
 770
 771    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T, cx: &mut ModelContext<Self>)
 772    where
 773        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
 774    {
 775        self.history
 776            .push_transaction(buffer_transactions, Instant::now(), cx);
 777        self.history.finalize_last_transaction();
 778    }
 779
 780    pub fn group_until_transaction(
 781        &mut self,
 782        transaction_id: TransactionId,
 783        cx: &mut ModelContext<Self>,
 784    ) {
 785        if let Some(buffer) = self.as_singleton() {
 786            buffer.update(cx, |buffer, _| {
 787                buffer.group_until_transaction(transaction_id)
 788            });
 789        } else {
 790            self.history.group_until(transaction_id);
 791        }
 792    }
 793
 794    pub fn set_active_selections(
 795        &mut self,
 796        selections: &[Selection<Anchor>],
 797        line_mode: bool,
 798        cursor_shape: CursorShape,
 799        cx: &mut ModelContext<Self>,
 800    ) {
 801        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
 802            Default::default();
 803        let snapshot = self.read(cx);
 804        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
 805        for selection in selections {
 806            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
 807            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
 808
 809            cursor.seek(&Some(start_locator), Bias::Left, &());
 810            while let Some(excerpt) = cursor.item() {
 811                if excerpt.locator > *end_locator {
 812                    break;
 813                }
 814
 815                let mut start = excerpt.range.context.start;
 816                let mut end = excerpt.range.context.end;
 817                if excerpt.id == selection.start.excerpt_id {
 818                    start = selection.start.text_anchor;
 819                }
 820                if excerpt.id == selection.end.excerpt_id {
 821                    end = selection.end.text_anchor;
 822                }
 823                selections_by_buffer
 824                    .entry(excerpt.buffer_id)
 825                    .or_default()
 826                    .push(Selection {
 827                        id: selection.id,
 828                        start,
 829                        end,
 830                        reversed: selection.reversed,
 831                        goal: selection.goal,
 832                    });
 833
 834                cursor.next(&());
 835            }
 836        }
 837
 838        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 839            if !selections_by_buffer.contains_key(buffer_id) {
 840                buffer_state
 841                    .buffer
 842                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 843            }
 844        }
 845
 846        for (buffer_id, mut selections) in selections_by_buffer {
 847            self.buffers.borrow()[&buffer_id]
 848                .buffer
 849                .update(cx, |buffer, cx| {
 850                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
 851                    let mut selections = selections.into_iter().peekable();
 852                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 853                        let mut selection = selections.next()?;
 854                        while let Some(next_selection) = selections.peek() {
 855                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
 856                                let next_selection = selections.next().unwrap();
 857                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
 858                                    selection.end = next_selection.end;
 859                                }
 860                            } else {
 861                                break;
 862                            }
 863                        }
 864                        Some(selection)
 865                    }));
 866                    buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
 867                });
 868        }
 869    }
 870
 871    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 872        for buffer in self.buffers.borrow().values() {
 873            buffer
 874                .buffer
 875                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 876        }
 877    }
 878
 879    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 880        let mut transaction_id = None;
 881        if let Some(buffer) = self.as_singleton() {
 882            transaction_id = buffer.update(cx, |buffer, cx| buffer.undo(cx));
 883        } else {
 884            while let Some(transaction) = self.history.pop_undo() {
 885                let mut undone = false;
 886                for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 887                    if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 888                        undone |= buffer.update(cx, |buffer, cx| {
 889                            let undo_to = *buffer_transaction_id;
 890                            if let Some(entry) = buffer.peek_undo_stack() {
 891                                *buffer_transaction_id = entry.transaction_id();
 892                            }
 893                            buffer.undo_to_transaction(undo_to, cx)
 894                        });
 895                    }
 896                }
 897
 898                if undone {
 899                    transaction_id = Some(transaction.id);
 900                    break;
 901                }
 902            }
 903        }
 904
 905        if let Some(transaction_id) = transaction_id {
 906            cx.emit(Event::TransactionUndone { transaction_id });
 907        }
 908
 909        transaction_id
 910    }
 911
 912    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 913        if let Some(buffer) = self.as_singleton() {
 914            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 915        }
 916
 917        while let Some(transaction) = self.history.pop_redo() {
 918            let mut redone = false;
 919            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 920                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 921                    redone |= buffer.update(cx, |buffer, cx| {
 922                        let redo_to = *buffer_transaction_id;
 923                        if let Some(entry) = buffer.peek_redo_stack() {
 924                            *buffer_transaction_id = entry.transaction_id();
 925                        }
 926                        buffer.redo_to_transaction(redo_to, cx)
 927                    });
 928                }
 929            }
 930
 931            if redone {
 932                return Some(transaction.id);
 933            }
 934        }
 935
 936        None
 937    }
 938
 939    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
 940        if let Some(buffer) = self.as_singleton() {
 941            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
 942        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
 943            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
 944                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
 945                    buffer.update(cx, |buffer, cx| {
 946                        buffer.undo_transaction(*transaction_id, cx)
 947                    });
 948                }
 949            }
 950        }
 951    }
 952
 953    pub fn stream_excerpts_with_context_lines(
 954        &mut self,
 955        buffer: Model<Buffer>,
 956        ranges: Vec<Range<text::Anchor>>,
 957        context_line_count: u32,
 958        cx: &mut ModelContext<Self>,
 959    ) -> mpsc::Receiver<Range<Anchor>> {
 960        let (buffer_id, buffer_snapshot) =
 961            buffer.update(cx, |buffer, _| (buffer.remote_id(), buffer.snapshot()));
 962
 963        let (mut tx, rx) = mpsc::channel(256);
 964        cx.spawn(move |this, mut cx| async move {
 965            let mut excerpt_ranges = Vec::new();
 966            let mut range_counts = Vec::new();
 967            cx.background_executor()
 968                .scoped(|scope| {
 969                    scope.spawn(async {
 970                        let (ranges, counts) =
 971                            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
 972                        excerpt_ranges = ranges;
 973                        range_counts = counts;
 974                    });
 975                })
 976                .await;
 977
 978            let mut ranges = ranges.into_iter();
 979            let mut range_counts = range_counts.into_iter();
 980            for excerpt_ranges in excerpt_ranges.chunks(100) {
 981                let excerpt_ids = match this.update(&mut cx, |this, cx| {
 982                    this.push_excerpts(buffer.clone(), excerpt_ranges.iter().cloned(), cx)
 983                }) {
 984                    Ok(excerpt_ids) => excerpt_ids,
 985                    Err(_) => return,
 986                };
 987
 988                for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.by_ref())
 989                {
 990                    for range in ranges.by_ref().take(range_count) {
 991                        let start = Anchor {
 992                            buffer_id: Some(buffer_id),
 993                            excerpt_id: excerpt_id,
 994                            text_anchor: range.start,
 995                        };
 996                        let end = Anchor {
 997                            buffer_id: Some(buffer_id),
 998                            excerpt_id: excerpt_id,
 999                            text_anchor: range.end,
1000                        };
1001                        if tx.send(start..end).await.is_err() {
1002                            break;
1003                        }
1004                    }
1005                }
1006            }
1007        })
1008        .detach();
1009
1010        rx
1011    }
1012
1013    pub fn push_excerpts<O>(
1014        &mut self,
1015        buffer: Model<Buffer>,
1016        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1017        cx: &mut ModelContext<Self>,
1018    ) -> Vec<ExcerptId>
1019    where
1020        O: text::ToOffset,
1021    {
1022        self.insert_excerpts_after(ExcerptId::max(), buffer, ranges, cx)
1023    }
1024
1025    pub fn push_excerpts_with_context_lines<O>(
1026        &mut self,
1027        buffer: Model<Buffer>,
1028        ranges: Vec<Range<O>>,
1029        context_line_count: u32,
1030        cx: &mut ModelContext<Self>,
1031    ) -> Vec<Range<Anchor>>
1032    where
1033        O: text::ToPoint + text::ToOffset,
1034    {
1035        let buffer_id = buffer.read(cx).remote_id();
1036        let buffer_snapshot = buffer.read(cx).snapshot();
1037        let (excerpt_ranges, range_counts) =
1038            build_excerpt_ranges(&buffer_snapshot, &ranges, context_line_count);
1039
1040        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
1041
1042        let mut anchor_ranges = Vec::new();
1043        let mut ranges = ranges.into_iter();
1044        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
1045            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
1046                let start = Anchor {
1047                    buffer_id: Some(buffer_id),
1048                    excerpt_id,
1049                    text_anchor: buffer_snapshot.anchor_after(range.start),
1050                };
1051                let end = Anchor {
1052                    buffer_id: Some(buffer_id),
1053                    excerpt_id,
1054                    text_anchor: buffer_snapshot.anchor_after(range.end),
1055                };
1056                start..end
1057            }))
1058        }
1059        anchor_ranges
1060    }
1061
1062    pub fn insert_excerpts_after<O>(
1063        &mut self,
1064        prev_excerpt_id: ExcerptId,
1065        buffer: Model<Buffer>,
1066        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1067        cx: &mut ModelContext<Self>,
1068    ) -> Vec<ExcerptId>
1069    where
1070        O: text::ToOffset,
1071    {
1072        let mut ids = Vec::new();
1073        let mut next_excerpt_id =
1074            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1075                last_entry.id.0 + 1
1076            } else {
1077                1
1078            };
1079        self.insert_excerpts_with_ids_after(
1080            prev_excerpt_id,
1081            buffer,
1082            ranges.into_iter().map(|range| {
1083                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1084                ids.push(id);
1085                (id, range)
1086            }),
1087            cx,
1088        );
1089        ids
1090    }
1091
1092    pub fn insert_excerpts_with_ids_after<O>(
1093        &mut self,
1094        prev_excerpt_id: ExcerptId,
1095        buffer: Model<Buffer>,
1096        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1097        cx: &mut ModelContext<Self>,
1098    ) where
1099        O: text::ToOffset,
1100    {
1101        assert_eq!(self.history.transaction_depth, 0);
1102        let mut ranges = ranges.into_iter().peekable();
1103        if ranges.peek().is_none() {
1104            return Default::default();
1105        }
1106
1107        self.sync(cx);
1108
1109        let buffer_id = buffer.read(cx).remote_id();
1110        let buffer_snapshot = buffer.read(cx).snapshot();
1111
1112        let mut buffers = self.buffers.borrow_mut();
1113        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
1114            last_version: buffer_snapshot.version().clone(),
1115            last_parse_count: buffer_snapshot.parse_count(),
1116            last_selections_update_count: buffer_snapshot.selections_update_count(),
1117            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
1118            last_file_update_count: buffer_snapshot.file_update_count(),
1119            last_git_diff_update_count: buffer_snapshot.git_diff_update_count(),
1120            excerpts: Default::default(),
1121            _subscriptions: [
1122                cx.observe(&buffer, |_, _, cx| cx.notify()),
1123                cx.subscribe(&buffer, Self::on_buffer_event),
1124            ],
1125            buffer: buffer.clone(),
1126        });
1127
1128        let mut snapshot = self.snapshot.borrow_mut();
1129
1130        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1131        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1132        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1133        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right, &());
1134        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1135
1136        let edit_start = new_excerpts.summary().text.len;
1137        new_excerpts.update_last(
1138            |excerpt| {
1139                excerpt.has_trailing_newline = true;
1140            },
1141            &(),
1142        );
1143
1144        let next_locator = if let Some(excerpt) = cursor.item() {
1145            excerpt.locator.clone()
1146        } else {
1147            Locator::max()
1148        };
1149
1150        let mut excerpts = Vec::new();
1151        while let Some((id, range)) = ranges.next() {
1152            let locator = Locator::between(&prev_locator, &next_locator);
1153            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1154                buffer_state.excerpts.insert(ix, locator.clone());
1155            }
1156            let range = ExcerptRange {
1157                context: buffer_snapshot.anchor_before(&range.context.start)
1158                    ..buffer_snapshot.anchor_after(&range.context.end),
1159                primary: range.primary.map(|primary| {
1160                    buffer_snapshot.anchor_before(&primary.start)
1161                        ..buffer_snapshot.anchor_after(&primary.end)
1162                }),
1163            };
1164            excerpts.push((id, range.clone()));
1165            let excerpt = Excerpt::new(
1166                id,
1167                locator.clone(),
1168                buffer_id,
1169                buffer_snapshot.clone(),
1170                range,
1171                ranges.peek().is_some() || cursor.item().is_some(),
1172            );
1173            new_excerpts.push(excerpt, &());
1174            prev_locator = locator.clone();
1175
1176            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1177                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1178            }
1179            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, &());
1180        }
1181
1182        let edit_end = new_excerpts.summary().text.len;
1183
1184        let suffix = cursor.suffix(&());
1185        let changed_trailing_excerpt = suffix.is_empty();
1186        new_excerpts.append(suffix, &());
1187        drop(cursor);
1188        snapshot.excerpts = new_excerpts;
1189        snapshot.excerpt_ids = new_excerpt_ids;
1190        if changed_trailing_excerpt {
1191            snapshot.trailing_excerpt_update_count += 1;
1192        }
1193
1194        self.subscriptions.publish_mut([Edit {
1195            old: edit_start..edit_start,
1196            new: edit_start..edit_end,
1197        }]);
1198        cx.emit(Event::Edited {
1199            singleton_buffer_edited: false,
1200        });
1201        cx.emit(Event::ExcerptsAdded {
1202            buffer,
1203            predecessor: prev_excerpt_id,
1204            excerpts,
1205        });
1206        cx.notify();
1207    }
1208
1209    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
1210        self.sync(cx);
1211        let ids = self.excerpt_ids();
1212        self.buffers.borrow_mut().clear();
1213        let mut snapshot = self.snapshot.borrow_mut();
1214        let prev_len = snapshot.len();
1215        snapshot.excerpts = Default::default();
1216        snapshot.trailing_excerpt_update_count += 1;
1217        snapshot.is_dirty = false;
1218        snapshot.has_conflict = false;
1219
1220        self.subscriptions.publish_mut([Edit {
1221            old: 0..prev_len,
1222            new: 0..0,
1223        }]);
1224        cx.emit(Event::Edited {
1225            singleton_buffer_edited: false,
1226        });
1227        cx.emit(Event::ExcerptsRemoved { ids });
1228        cx.notify();
1229    }
1230
1231    pub fn excerpts_for_buffer(
1232        &self,
1233        buffer: &Model<Buffer>,
1234        cx: &AppContext,
1235    ) -> Vec<(ExcerptId, ExcerptRange<text::Anchor>)> {
1236        let mut excerpts = Vec::new();
1237        let snapshot = self.read(cx);
1238        let buffers = self.buffers.borrow();
1239        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>();
1240        for locator in buffers
1241            .get(&buffer.read(cx).remote_id())
1242            .map(|state| &state.excerpts)
1243            .into_iter()
1244            .flatten()
1245        {
1246            cursor.seek_forward(&Some(locator), Bias::Left, &());
1247            if let Some(excerpt) = cursor.item() {
1248                if excerpt.locator == *locator {
1249                    excerpts.push((excerpt.id, excerpt.range.clone()));
1250                }
1251            }
1252        }
1253
1254        excerpts
1255    }
1256
1257    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
1258        self.snapshot
1259            .borrow()
1260            .excerpts
1261            .iter()
1262            .map(|entry| entry.id)
1263            .collect()
1264    }
1265
1266    pub fn excerpt_containing(
1267        &self,
1268        position: impl ToOffset,
1269        cx: &AppContext,
1270    ) -> Option<(ExcerptId, Model<Buffer>, Range<text::Anchor>)> {
1271        let snapshot = self.read(cx);
1272        let position = position.to_offset(&snapshot);
1273
1274        let mut cursor = snapshot.excerpts.cursor::<usize>();
1275        cursor.seek(&position, Bias::Right, &());
1276        cursor
1277            .item()
1278            .or_else(|| snapshot.excerpts.last())
1279            .map(|excerpt| {
1280                (
1281                    excerpt.id,
1282                    self.buffers
1283                        .borrow()
1284                        .get(&excerpt.buffer_id)
1285                        .unwrap()
1286                        .buffer
1287                        .clone(),
1288                    excerpt.range.context.clone(),
1289                )
1290            })
1291    }
1292
1293    // If point is at the end of the buffer, the last excerpt is returned
1294    pub fn point_to_buffer_offset<T: ToOffset>(
1295        &self,
1296        point: T,
1297        cx: &AppContext,
1298    ) -> Option<(Model<Buffer>, usize, ExcerptId)> {
1299        let snapshot = self.read(cx);
1300        let offset = point.to_offset(&snapshot);
1301        let mut cursor = snapshot.excerpts.cursor::<usize>();
1302        cursor.seek(&offset, Bias::Right, &());
1303        if cursor.item().is_none() {
1304            cursor.prev(&());
1305        }
1306
1307        cursor.item().map(|excerpt| {
1308            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1309            let buffer_point = excerpt_start + offset - *cursor.start();
1310            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1311
1312            (buffer, buffer_point, excerpt.id)
1313        })
1314    }
1315
1316    pub fn range_to_buffer_ranges<T: ToOffset>(
1317        &self,
1318        range: Range<T>,
1319        cx: &AppContext,
1320    ) -> Vec<(Model<Buffer>, Range<usize>, ExcerptId)> {
1321        let snapshot = self.read(cx);
1322        let start = range.start.to_offset(&snapshot);
1323        let end = range.end.to_offset(&snapshot);
1324
1325        let mut result = Vec::new();
1326        let mut cursor = snapshot.excerpts.cursor::<usize>();
1327        cursor.seek(&start, Bias::Right, &());
1328        if cursor.item().is_none() {
1329            cursor.prev(&());
1330        }
1331
1332        while let Some(excerpt) = cursor.item() {
1333            if *cursor.start() > end {
1334                break;
1335            }
1336
1337            let mut end_before_newline = cursor.end(&());
1338            if excerpt.has_trailing_newline {
1339                end_before_newline -= 1;
1340            }
1341            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
1342            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
1343            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
1344            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
1345            result.push((buffer, start..end, excerpt.id));
1346            cursor.next(&());
1347        }
1348
1349        result
1350    }
1351
1352    pub fn remove_excerpts(
1353        &mut self,
1354        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
1355        cx: &mut ModelContext<Self>,
1356    ) {
1357        self.sync(cx);
1358        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
1359        if ids.is_empty() {
1360            return;
1361        }
1362
1363        let mut buffers = self.buffers.borrow_mut();
1364        let mut snapshot = self.snapshot.borrow_mut();
1365        let mut new_excerpts = SumTree::new();
1366        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1367        let mut edits = Vec::new();
1368        let mut excerpt_ids = ids.iter().copied().peekable();
1369
1370        while let Some(excerpt_id) = excerpt_ids.next() {
1371            // Seek to the next excerpt to remove, preserving any preceding excerpts.
1372            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
1373            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1374
1375            if let Some(mut excerpt) = cursor.item() {
1376                if excerpt.id != excerpt_id {
1377                    continue;
1378                }
1379                let mut old_start = cursor.start().1;
1380
1381                // Skip over the removed excerpt.
1382                'remove_excerpts: loop {
1383                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
1384                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
1385                        if buffer_state.excerpts.is_empty() {
1386                            buffers.remove(&excerpt.buffer_id);
1387                        }
1388                    }
1389                    cursor.next(&());
1390
1391                    // Skip over any subsequent excerpts that are also removed.
1392                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
1393                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
1394                        if let Some(next_excerpt) = cursor.item() {
1395                            if next_excerpt.locator == *next_locator {
1396                                excerpt_ids.next();
1397                                excerpt = next_excerpt;
1398                                continue 'remove_excerpts;
1399                            }
1400                        }
1401                    }
1402
1403                    break;
1404                }
1405
1406                // When removing the last excerpt, remove the trailing newline from
1407                // the previous excerpt.
1408                if cursor.item().is_none() && old_start > 0 {
1409                    old_start -= 1;
1410                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
1411                }
1412
1413                // Push an edit for the removal of this run of excerpts.
1414                let old_end = cursor.start().1;
1415                let new_start = new_excerpts.summary().text.len;
1416                edits.push(Edit {
1417                    old: old_start..old_end,
1418                    new: new_start..new_start,
1419                });
1420            }
1421        }
1422        let suffix = cursor.suffix(&());
1423        let changed_trailing_excerpt = suffix.is_empty();
1424        new_excerpts.append(suffix, &());
1425        drop(cursor);
1426        snapshot.excerpts = new_excerpts;
1427
1428        if changed_trailing_excerpt {
1429            snapshot.trailing_excerpt_update_count += 1;
1430        }
1431
1432        self.subscriptions.publish_mut(edits);
1433        cx.emit(Event::Edited {
1434            singleton_buffer_edited: false,
1435        });
1436        cx.emit(Event::ExcerptsRemoved { ids });
1437        cx.notify();
1438    }
1439
1440    pub fn wait_for_anchors<'a>(
1441        &self,
1442        anchors: impl 'a + Iterator<Item = Anchor>,
1443        cx: &mut ModelContext<Self>,
1444    ) -> impl 'static + Future<Output = Result<()>> {
1445        let borrow = self.buffers.borrow();
1446        let mut error = None;
1447        let mut futures = Vec::new();
1448        for anchor in anchors {
1449            if let Some(buffer_id) = anchor.buffer_id {
1450                if let Some(buffer) = borrow.get(&buffer_id) {
1451                    buffer.buffer.update(cx, |buffer, _| {
1452                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
1453                    });
1454                } else {
1455                    error = Some(anyhow!(
1456                        "buffer {buffer_id} is not part of this multi-buffer"
1457                    ));
1458                    break;
1459                }
1460            }
1461        }
1462        async move {
1463            if let Some(error) = error {
1464                Err(error)?;
1465            }
1466            for future in futures {
1467                future.await?;
1468            }
1469            Ok(())
1470        }
1471    }
1472
1473    pub fn text_anchor_for_position<T: ToOffset>(
1474        &self,
1475        position: T,
1476        cx: &AppContext,
1477    ) -> Option<(Model<Buffer>, language::Anchor)> {
1478        let snapshot = self.read(cx);
1479        let anchor = snapshot.anchor_before(position);
1480        let buffer = self
1481            .buffers
1482            .borrow()
1483            .get(&anchor.buffer_id?)?
1484            .buffer
1485            .clone();
1486        Some((buffer, anchor.text_anchor))
1487    }
1488
1489    fn on_buffer_event(
1490        &mut self,
1491        buffer: Model<Buffer>,
1492        event: &language::Event,
1493        cx: &mut ModelContext<Self>,
1494    ) {
1495        cx.emit(match event {
1496            language::Event::Edited => Event::Edited {
1497                singleton_buffer_edited: true,
1498            },
1499            language::Event::DirtyChanged => Event::DirtyChanged,
1500            language::Event::Saved => Event::Saved,
1501            language::Event::FileHandleChanged => Event::FileHandleChanged,
1502            language::Event::Reloaded => Event::Reloaded,
1503            language::Event::DiffBaseChanged => Event::DiffBaseChanged,
1504            language::Event::DiffUpdated => Event::DiffUpdated { buffer },
1505            language::Event::LanguageChanged => Event::LanguageChanged,
1506            language::Event::Reparsed => Event::Reparsed,
1507            language::Event::DiagnosticsUpdated => Event::DiagnosticsUpdated,
1508            language::Event::Closed => Event::Closed,
1509            language::Event::CapabilityChanged => {
1510                self.capability = buffer.read(cx).capability();
1511                Event::CapabilityChanged
1512            }
1513
1514            //
1515            language::Event::Operation(_) => return,
1516        });
1517    }
1518
1519    pub fn all_buffers(&self) -> HashSet<Model<Buffer>> {
1520        self.buffers
1521            .borrow()
1522            .values()
1523            .map(|state| state.buffer.clone())
1524            .collect()
1525    }
1526
1527    pub fn buffer(&self, buffer_id: BufferId) -> Option<Model<Buffer>> {
1528        self.buffers
1529            .borrow()
1530            .get(&buffer_id)
1531            .map(|state| state.buffer.clone())
1532    }
1533
1534    pub fn is_completion_trigger(
1535        &self,
1536        position: Anchor,
1537        text: &str,
1538        trigger_in_words: bool,
1539        cx: &AppContext,
1540    ) -> bool {
1541        let mut chars = text.chars();
1542        let char = if let Some(char) = chars.next() {
1543            char
1544        } else {
1545            return false;
1546        };
1547        if chars.next().is_some() {
1548            return false;
1549        }
1550
1551        let snapshot = self.snapshot(cx);
1552        let position = position.to_offset(&snapshot);
1553        let scope = snapshot.language_scope_at(position);
1554        if trigger_in_words && char_kind(&scope, char) == CharKind::Word {
1555            return true;
1556        }
1557
1558        let anchor = snapshot.anchor_before(position);
1559        anchor
1560            .buffer_id
1561            .and_then(|buffer_id| {
1562                let buffer = self.buffers.borrow().get(&buffer_id)?.buffer.clone();
1563                Some(
1564                    buffer
1565                        .read(cx)
1566                        .completion_triggers()
1567                        .iter()
1568                        .any(|string| string == text),
1569                )
1570            })
1571            .unwrap_or(false)
1572    }
1573
1574    pub fn language_at<T: ToOffset>(&self, point: T, cx: &AppContext) -> Option<Arc<Language>> {
1575        self.point_to_buffer_offset(point, cx)
1576            .and_then(|(buffer, offset, _)| buffer.read(cx).language_at(offset))
1577    }
1578
1579    pub fn settings_at<'a, T: ToOffset>(
1580        &self,
1581        point: T,
1582        cx: &'a AppContext,
1583    ) -> &'a LanguageSettings {
1584        let mut language = None;
1585        let mut file = None;
1586        if let Some((buffer, offset, _)) = self.point_to_buffer_offset(point, cx) {
1587            let buffer = buffer.read(cx);
1588            language = buffer.language_at(offset);
1589            file = buffer.file();
1590        }
1591        language_settings(language.as_ref(), file, cx)
1592    }
1593
1594    pub fn for_each_buffer(&self, mut f: impl FnMut(&Model<Buffer>)) {
1595        self.buffers
1596            .borrow()
1597            .values()
1598            .for_each(|state| f(&state.buffer))
1599    }
1600
1601    pub fn title<'a>(&'a self, cx: &'a AppContext) -> Cow<'a, str> {
1602        if let Some(title) = self.title.as_ref() {
1603            return title.into();
1604        }
1605
1606        if let Some(buffer) = self.as_singleton() {
1607            if let Some(file) = buffer.read(cx).file() {
1608                return file.file_name(cx).to_string_lossy();
1609            }
1610        }
1611
1612        "untitled".into()
1613    }
1614
1615    pub fn set_title(&mut self, title: String, cx: &mut ModelContext<Self>) {
1616        self.title = Some(title);
1617        cx.notify();
1618    }
1619
1620    #[cfg(any(test, feature = "test-support"))]
1621    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1622        self.as_singleton().unwrap().read(cx).is_parsing()
1623    }
1624
1625    pub fn expand_excerpts(
1626        &mut self,
1627        ids: impl IntoIterator<Item = ExcerptId>,
1628        line_count: u32,
1629        cx: &mut ModelContext<Self>,
1630    ) {
1631        if line_count == 0 {
1632            return;
1633        }
1634        self.sync(cx);
1635
1636        let snapshot = self.snapshot(cx);
1637        let locators = snapshot.excerpt_locators_for_ids(ids);
1638        let mut new_excerpts = SumTree::new();
1639        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1640        let mut edits = Vec::<Edit<usize>>::new();
1641
1642        for locator in &locators {
1643            let prefix = cursor.slice(&Some(locator), Bias::Left, &());
1644            new_excerpts.append(prefix, &());
1645
1646            let mut excerpt = cursor.item().unwrap().clone();
1647            let old_text_len = excerpt.text_summary.len;
1648
1649            let start_row = excerpt
1650                .range
1651                .context
1652                .start
1653                .to_point(&excerpt.buffer)
1654                .row
1655                .saturating_sub(line_count);
1656            let start_point = Point::new(start_row, 0);
1657            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
1658
1659            let end_point = excerpt.buffer.clip_point(
1660                excerpt.range.context.end.to_point(&excerpt.buffer) + Point::new(line_count, 0),
1661                Bias::Left,
1662            );
1663            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
1664            excerpt.max_buffer_row = end_point.row;
1665
1666            excerpt.text_summary = excerpt
1667                .buffer
1668                .text_summary_for_range(start_point..end_point);
1669
1670            let new_start_offset = new_excerpts.summary().text.len;
1671            let old_start_offset = cursor.start().1;
1672            let edit = Edit {
1673                old: old_start_offset..old_start_offset + old_text_len,
1674                new: new_start_offset..new_start_offset + excerpt.text_summary.len,
1675            };
1676
1677            if let Some(last_edit) = edits.last_mut() {
1678                if last_edit.old.end == edit.old.start {
1679                    last_edit.old.end = edit.old.end;
1680                    last_edit.new.end = edit.new.end;
1681                } else {
1682                    edits.push(edit);
1683                }
1684            } else {
1685                edits.push(edit);
1686            }
1687
1688            new_excerpts.push(excerpt, &());
1689
1690            cursor.next(&());
1691        }
1692
1693        new_excerpts.append(cursor.suffix(&()), &());
1694
1695        drop(cursor);
1696        self.snapshot.borrow_mut().excerpts = new_excerpts;
1697
1698        self.subscriptions.publish_mut(edits);
1699        cx.emit(Event::Edited {
1700            singleton_buffer_edited: false,
1701        });
1702        cx.notify();
1703    }
1704
1705    fn sync(&self, cx: &AppContext) {
1706        let mut snapshot = self.snapshot.borrow_mut();
1707        let mut excerpts_to_edit = Vec::new();
1708        let mut reparsed = false;
1709        let mut diagnostics_updated = false;
1710        let mut git_diff_updated = false;
1711        let mut is_dirty = false;
1712        let mut has_conflict = false;
1713        let mut edited = false;
1714        let mut buffers = self.buffers.borrow_mut();
1715        for buffer_state in buffers.values_mut() {
1716            let buffer = buffer_state.buffer.read(cx);
1717            let version = buffer.version();
1718            let parse_count = buffer.parse_count();
1719            let selections_update_count = buffer.selections_update_count();
1720            let diagnostics_update_count = buffer.diagnostics_update_count();
1721            let file_update_count = buffer.file_update_count();
1722            let git_diff_update_count = buffer.git_diff_update_count();
1723
1724            let buffer_edited = version.changed_since(&buffer_state.last_version);
1725            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1726            let buffer_selections_updated =
1727                selections_update_count > buffer_state.last_selections_update_count;
1728            let buffer_diagnostics_updated =
1729                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1730            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1731            let buffer_git_diff_updated =
1732                git_diff_update_count > buffer_state.last_git_diff_update_count;
1733            if buffer_edited
1734                || buffer_reparsed
1735                || buffer_selections_updated
1736                || buffer_diagnostics_updated
1737                || buffer_file_updated
1738                || buffer_git_diff_updated
1739            {
1740                buffer_state.last_version = version;
1741                buffer_state.last_parse_count = parse_count;
1742                buffer_state.last_selections_update_count = selections_update_count;
1743                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1744                buffer_state.last_file_update_count = file_update_count;
1745                buffer_state.last_git_diff_update_count = git_diff_update_count;
1746                excerpts_to_edit.extend(
1747                    buffer_state
1748                        .excerpts
1749                        .iter()
1750                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
1751                );
1752            }
1753
1754            edited |= buffer_edited;
1755            reparsed |= buffer_reparsed;
1756            diagnostics_updated |= buffer_diagnostics_updated;
1757            git_diff_updated |= buffer_git_diff_updated;
1758            is_dirty |= buffer.is_dirty();
1759            has_conflict |= buffer.has_conflict();
1760        }
1761        if edited {
1762            snapshot.edit_count += 1;
1763        }
1764        if reparsed {
1765            snapshot.parse_count += 1;
1766        }
1767        if diagnostics_updated {
1768            snapshot.diagnostics_update_count += 1;
1769        }
1770        if git_diff_updated {
1771            snapshot.git_diff_update_count += 1;
1772        }
1773        snapshot.is_dirty = is_dirty;
1774        snapshot.has_conflict = has_conflict;
1775
1776        excerpts_to_edit.sort_unstable_by_key(|(locator, _, _)| *locator);
1777
1778        let mut edits = Vec::new();
1779        let mut new_excerpts = SumTree::new();
1780        let mut cursor = snapshot.excerpts.cursor::<(Option<&Locator>, usize)>();
1781
1782        for (locator, buffer, buffer_edited) in excerpts_to_edit {
1783            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left, &()), &());
1784            let old_excerpt = cursor.item().unwrap();
1785            let buffer = buffer.read(cx);
1786            let buffer_id = buffer.remote_id();
1787
1788            let mut new_excerpt;
1789            if buffer_edited {
1790                edits.extend(
1791                    buffer
1792                        .edits_since_in_range::<usize>(
1793                            old_excerpt.buffer.version(),
1794                            old_excerpt.range.context.clone(),
1795                        )
1796                        .map(|mut edit| {
1797                            let excerpt_old_start = cursor.start().1;
1798                            let excerpt_new_start = new_excerpts.summary().text.len;
1799                            edit.old.start += excerpt_old_start;
1800                            edit.old.end += excerpt_old_start;
1801                            edit.new.start += excerpt_new_start;
1802                            edit.new.end += excerpt_new_start;
1803                            edit
1804                        }),
1805                );
1806
1807                new_excerpt = Excerpt::new(
1808                    old_excerpt.id,
1809                    locator.clone(),
1810                    buffer_id,
1811                    buffer.snapshot(),
1812                    old_excerpt.range.clone(),
1813                    old_excerpt.has_trailing_newline,
1814                );
1815            } else {
1816                new_excerpt = old_excerpt.clone();
1817                new_excerpt.buffer = buffer.snapshot();
1818            }
1819
1820            new_excerpts.push(new_excerpt, &());
1821            cursor.next(&());
1822        }
1823        new_excerpts.append(cursor.suffix(&()), &());
1824
1825        drop(cursor);
1826        snapshot.excerpts = new_excerpts;
1827
1828        self.subscriptions.publish(edits);
1829    }
1830}
1831
1832#[cfg(any(test, feature = "test-support"))]
1833impl MultiBuffer {
1834    pub fn build_simple(text: &str, cx: &mut gpui::AppContext) -> Model<Self> {
1835        let buffer = cx.new_model(|cx| Buffer::local(text, cx));
1836        cx.new_model(|cx| Self::singleton(buffer, cx))
1837    }
1838
1839    pub fn build_multi<const COUNT: usize>(
1840        excerpts: [(&str, Vec<Range<Point>>); COUNT],
1841        cx: &mut gpui::AppContext,
1842    ) -> Model<Self> {
1843        let multi = cx.new_model(|_| Self::new(0, Capability::ReadWrite));
1844        for (text, ranges) in excerpts {
1845            let buffer = cx.new_model(|cx| Buffer::local(text, cx));
1846            let excerpt_ranges = ranges.into_iter().map(|range| ExcerptRange {
1847                context: range,
1848                primary: None,
1849            });
1850            multi.update(cx, |multi, cx| {
1851                multi.push_excerpts(buffer, excerpt_ranges, cx)
1852            });
1853        }
1854
1855        multi
1856    }
1857
1858    pub fn build_from_buffer(buffer: Model<Buffer>, cx: &mut gpui::AppContext) -> Model<Self> {
1859        cx.new_model(|cx| Self::singleton(buffer, cx))
1860    }
1861
1862    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::AppContext) -> Model<Self> {
1863        cx.new_model(|cx| {
1864            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
1865            let mutation_count = rng.gen_range(1..=5);
1866            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
1867            multibuffer
1868        })
1869    }
1870
1871    pub fn randomly_edit(
1872        &mut self,
1873        rng: &mut impl rand::Rng,
1874        edit_count: usize,
1875        cx: &mut ModelContext<Self>,
1876    ) {
1877        use util::RandomCharIter;
1878
1879        let snapshot = self.read(cx);
1880        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1881        let mut last_end = None;
1882        for _ in 0..edit_count {
1883            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
1884                break;
1885            }
1886
1887            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1888            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
1889            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
1890            last_end = Some(end);
1891
1892            let mut range = start..end;
1893            if rng.gen_bool(0.2) {
1894                mem::swap(&mut range.start, &mut range.end);
1895            }
1896
1897            let new_text_len = rng.gen_range(0..10);
1898            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1899
1900            edits.push((range, new_text.into()));
1901        }
1902        log::info!("mutating multi-buffer with {:?}", edits);
1903        drop(snapshot);
1904
1905        self.edit(edits, None, cx);
1906    }
1907
1908    pub fn randomly_edit_excerpts(
1909        &mut self,
1910        rng: &mut impl rand::Rng,
1911        mutation_count: usize,
1912        cx: &mut ModelContext<Self>,
1913    ) {
1914        use rand::prelude::*;
1915        use std::env;
1916        use util::RandomCharIter;
1917
1918        let max_excerpts = env::var("MAX_EXCERPTS")
1919            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1920            .unwrap_or(5);
1921
1922        let mut buffers = Vec::new();
1923        for _ in 0..mutation_count {
1924            if rng.gen_bool(0.05) {
1925                log::info!("Clearing multi-buffer");
1926                self.clear(cx);
1927                continue;
1928            } else if rng.gen_bool(0.1) && !self.excerpt_ids().is_empty() {
1929                let ids = self.excerpt_ids();
1930                let mut excerpts = HashSet::default();
1931                for _ in 0..rng.gen_range(0..ids.len()) {
1932                    excerpts.extend(ids.choose(rng).copied());
1933                }
1934
1935                let line_count = rng.gen_range(0..5);
1936
1937                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
1938
1939                self.expand_excerpts(excerpts.iter().cloned(), line_count, cx);
1940                continue;
1941            }
1942
1943            let excerpt_ids = self.excerpt_ids();
1944            if excerpt_ids.is_empty() || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1945                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1946                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1947                    buffers.push(cx.new_model(|cx| Buffer::local(text, cx)));
1948                    let buffer = buffers.last().unwrap().read(cx);
1949                    log::info!(
1950                        "Creating new buffer {} with text: {:?}",
1951                        buffer.remote_id(),
1952                        buffer.text()
1953                    );
1954                    buffers.last().unwrap().clone()
1955                } else {
1956                    self.buffers
1957                        .borrow()
1958                        .values()
1959                        .choose(rng)
1960                        .unwrap()
1961                        .buffer
1962                        .clone()
1963                };
1964
1965                let buffer = buffer_handle.read(cx);
1966                let buffer_text = buffer.text();
1967                let ranges = (0..rng.gen_range(0..5))
1968                    .map(|_| {
1969                        let end_ix =
1970                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1971                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1972                        ExcerptRange {
1973                            context: start_ix..end_ix,
1974                            primary: None,
1975                        }
1976                    })
1977                    .collect::<Vec<_>>();
1978                log::info!(
1979                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
1980                    buffer_handle.read(cx).remote_id(),
1981                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
1982                    ranges
1983                        .iter()
1984                        .map(|r| &buffer_text[r.context.clone()])
1985                        .collect::<Vec<_>>()
1986                );
1987
1988                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
1989                log::info!("Inserted with ids: {:?}", excerpt_id);
1990            } else {
1991                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1992                let mut excerpts_to_remove = excerpt_ids
1993                    .choose_multiple(rng, remove_count)
1994                    .cloned()
1995                    .collect::<Vec<_>>();
1996                let snapshot = self.snapshot.borrow();
1997                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
1998                drop(snapshot);
1999                log::info!("Removing excerpts {:?}", excerpts_to_remove);
2000                self.remove_excerpts(excerpts_to_remove, cx);
2001            }
2002        }
2003    }
2004
2005    pub fn randomly_mutate(
2006        &mut self,
2007        rng: &mut impl rand::Rng,
2008        mutation_count: usize,
2009        cx: &mut ModelContext<Self>,
2010    ) {
2011        use rand::prelude::*;
2012
2013        if rng.gen_bool(0.7) || self.singleton {
2014            let buffer = self
2015                .buffers
2016                .borrow()
2017                .values()
2018                .choose(rng)
2019                .map(|state| state.buffer.clone());
2020
2021            if let Some(buffer) = buffer {
2022                buffer.update(cx, |buffer, cx| {
2023                    if rng.gen() {
2024                        buffer.randomly_edit(rng, mutation_count, cx);
2025                    } else {
2026                        buffer.randomly_undo_redo(rng, cx);
2027                    }
2028                });
2029            } else {
2030                self.randomly_edit(rng, mutation_count, cx);
2031            }
2032        } else {
2033            self.randomly_edit_excerpts(rng, mutation_count, cx);
2034        }
2035
2036        self.check_invariants(cx);
2037    }
2038
2039    fn check_invariants(&self, cx: &mut ModelContext<Self>) {
2040        let snapshot = self.read(cx);
2041        let excerpts = snapshot.excerpts.items(&());
2042        let excerpt_ids = snapshot.excerpt_ids.items(&());
2043
2044        for (ix, excerpt) in excerpts.iter().enumerate() {
2045            if ix == 0 {
2046                if excerpt.locator <= Locator::min() {
2047                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
2048                }
2049            } else {
2050                if excerpt.locator <= excerpts[ix - 1].locator {
2051                    panic!("excerpts are out-of-order: {:?}", excerpts);
2052                }
2053            }
2054        }
2055
2056        for (ix, entry) in excerpt_ids.iter().enumerate() {
2057            if ix == 0 {
2058                if entry.id.cmp(&ExcerptId::min(), &snapshot).is_le() {
2059                    panic!("invalid first excerpt id {:?}", entry.id);
2060                }
2061            } else {
2062                if entry.id <= excerpt_ids[ix - 1].id {
2063                    panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
2064                }
2065            }
2066        }
2067    }
2068}
2069
2070impl EventEmitter<Event> for MultiBuffer {}
2071
2072impl MultiBufferSnapshot {
2073    pub fn text(&self) -> String {
2074        self.chunks(0..self.len(), false)
2075            .map(|chunk| chunk.text)
2076            .collect()
2077    }
2078
2079    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2080        let mut offset = position.to_offset(self);
2081        let mut cursor = self.excerpts.cursor::<usize>();
2082        cursor.seek(&offset, Bias::Left, &());
2083        let mut excerpt_chunks = cursor.item().map(|excerpt| {
2084            let end_before_footer = cursor.start() + excerpt.text_summary.len;
2085            let start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2086            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
2087            excerpt.buffer.reversed_chunks_in_range(start..end)
2088        });
2089        iter::from_fn(move || {
2090            if offset == *cursor.start() {
2091                cursor.prev(&());
2092                let excerpt = cursor.item()?;
2093                excerpt_chunks = Some(
2094                    excerpt
2095                        .buffer
2096                        .reversed_chunks_in_range(excerpt.range.context.clone()),
2097                );
2098            }
2099
2100            let excerpt = cursor.item().unwrap();
2101            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
2102                offset -= 1;
2103                Some("\n")
2104            } else {
2105                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
2106                offset -= chunk.len();
2107                Some(chunk)
2108            }
2109        })
2110        .flat_map(|c| c.chars().rev())
2111    }
2112
2113    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
2114        let offset = position.to_offset(self);
2115        self.text_for_range(offset..self.len())
2116            .flat_map(|chunk| chunk.chars())
2117    }
2118
2119    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
2120        self.chunks(range, false).map(|chunk| chunk.text)
2121    }
2122
2123    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
2124        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
2125            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
2126    }
2127
2128    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
2129    where
2130        T: ToOffset,
2131    {
2132        let position = position.to_offset(self);
2133        position == self.clip_offset(position, Bias::Left)
2134            && self
2135                .bytes_in_range(position..self.len())
2136                .flatten()
2137                .copied()
2138                .take(needle.len())
2139                .eq(needle.bytes())
2140    }
2141
2142    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
2143        let mut start = start.to_offset(self);
2144        let mut end = start;
2145        let mut next_chars = self.chars_at(start).peekable();
2146        let mut prev_chars = self.reversed_chars_at(start).peekable();
2147
2148        let scope = self.language_scope_at(start);
2149        let kind = |c| char_kind(&scope, c);
2150        let word_kind = cmp::max(
2151            prev_chars.peek().copied().map(kind),
2152            next_chars.peek().copied().map(kind),
2153        );
2154
2155        for ch in prev_chars {
2156            if Some(kind(ch)) == word_kind && ch != '\n' {
2157                start -= ch.len_utf8();
2158            } else {
2159                break;
2160            }
2161        }
2162
2163        for ch in next_chars {
2164            if Some(kind(ch)) == word_kind && ch != '\n' {
2165                end += ch.len_utf8();
2166            } else {
2167                break;
2168            }
2169        }
2170
2171        (start..end, word_kind)
2172    }
2173
2174    pub fn as_singleton(&self) -> Option<(&ExcerptId, BufferId, &BufferSnapshot)> {
2175        if self.singleton {
2176            self.excerpts
2177                .iter()
2178                .next()
2179                .map(|e| (&e.id, e.buffer_id, &e.buffer))
2180        } else {
2181            None
2182        }
2183    }
2184
2185    pub fn len(&self) -> usize {
2186        self.excerpts.summary().text.len
2187    }
2188
2189    pub fn is_empty(&self) -> bool {
2190        self.excerpts.summary().text.len == 0
2191    }
2192
2193    pub fn max_buffer_row(&self) -> MultiBufferRow {
2194        self.excerpts.summary().max_buffer_row
2195    }
2196
2197    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
2198        if let Some((_, _, buffer)) = self.as_singleton() {
2199            return buffer.clip_offset(offset, bias);
2200        }
2201
2202        let mut cursor = self.excerpts.cursor::<usize>();
2203        cursor.seek(&offset, Bias::Right, &());
2204        let overshoot = if let Some(excerpt) = cursor.item() {
2205            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2206            let buffer_offset = excerpt
2207                .buffer
2208                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
2209            buffer_offset.saturating_sub(excerpt_start)
2210        } else {
2211            0
2212        };
2213        cursor.start() + overshoot
2214    }
2215
2216    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
2217        if let Some((_, _, buffer)) = self.as_singleton() {
2218            return buffer.clip_point(point, bias);
2219        }
2220
2221        let mut cursor = self.excerpts.cursor::<Point>();
2222        cursor.seek(&point, Bias::Right, &());
2223        let overshoot = if let Some(excerpt) = cursor.item() {
2224            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2225            let buffer_point = excerpt
2226                .buffer
2227                .clip_point(excerpt_start + (point - cursor.start()), bias);
2228            buffer_point.saturating_sub(excerpt_start)
2229        } else {
2230            Point::zero()
2231        };
2232        *cursor.start() + overshoot
2233    }
2234
2235    pub fn clip_offset_utf16(&self, offset: OffsetUtf16, bias: Bias) -> OffsetUtf16 {
2236        if let Some((_, _, buffer)) = self.as_singleton() {
2237            return buffer.clip_offset_utf16(offset, bias);
2238        }
2239
2240        let mut cursor = self.excerpts.cursor::<OffsetUtf16>();
2241        cursor.seek(&offset, Bias::Right, &());
2242        let overshoot = if let Some(excerpt) = cursor.item() {
2243            let excerpt_start = excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2244            let buffer_offset = excerpt
2245                .buffer
2246                .clip_offset_utf16(excerpt_start + (offset - cursor.start()), bias);
2247            OffsetUtf16(buffer_offset.0.saturating_sub(excerpt_start.0))
2248        } else {
2249            OffsetUtf16(0)
2250        };
2251        *cursor.start() + overshoot
2252    }
2253
2254    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
2255        if let Some((_, _, buffer)) = self.as_singleton() {
2256            return buffer.clip_point_utf16(point, bias);
2257        }
2258
2259        let mut cursor = self.excerpts.cursor::<PointUtf16>();
2260        cursor.seek(&point.0, Bias::Right, &());
2261        let overshoot = if let Some(excerpt) = cursor.item() {
2262            let excerpt_start = excerpt
2263                .buffer
2264                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2265            let buffer_point = excerpt
2266                .buffer
2267                .clip_point_utf16(Unclipped(excerpt_start + (point.0 - cursor.start())), bias);
2268            buffer_point.saturating_sub(excerpt_start)
2269        } else {
2270            PointUtf16::zero()
2271        };
2272        *cursor.start() + overshoot
2273    }
2274
2275    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes {
2276        let range = range.start.to_offset(self)..range.end.to_offset(self);
2277        let mut excerpts = self.excerpts.cursor::<usize>();
2278        excerpts.seek(&range.start, Bias::Right, &());
2279
2280        let mut chunk = &[][..];
2281        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2282            let mut excerpt_bytes = excerpt
2283                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
2284            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2285            Some(excerpt_bytes)
2286        } else {
2287            None
2288        };
2289        MultiBufferBytes {
2290            range,
2291            excerpts,
2292            excerpt_bytes,
2293            chunk,
2294        }
2295    }
2296
2297    pub fn reversed_bytes_in_range<T: ToOffset>(
2298        &self,
2299        range: Range<T>,
2300    ) -> ReversedMultiBufferBytes {
2301        let range = range.start.to_offset(self)..range.end.to_offset(self);
2302        let mut excerpts = self.excerpts.cursor::<usize>();
2303        excerpts.seek(&range.end, Bias::Left, &());
2304
2305        let mut chunk = &[][..];
2306        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
2307            let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
2308                range.start.saturating_sub(*excerpts.start())..range.end - *excerpts.start(),
2309            );
2310            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
2311            Some(excerpt_bytes)
2312        } else {
2313            None
2314        };
2315
2316        ReversedMultiBufferBytes {
2317            range,
2318            excerpts,
2319            excerpt_bytes,
2320            chunk,
2321        }
2322    }
2323
2324    pub fn buffer_rows(&self, start_row: MultiBufferRow) -> MultiBufferRows {
2325        let mut result = MultiBufferRows {
2326            buffer_row_range: 0..0,
2327            excerpts: self.excerpts.cursor(),
2328        };
2329        result.seek(start_row);
2330        result
2331    }
2332
2333    pub fn chunks<T: ToOffset>(&self, range: Range<T>, language_aware: bool) -> MultiBufferChunks {
2334        let range = range.start.to_offset(self)..range.end.to_offset(self);
2335        let mut chunks = MultiBufferChunks {
2336            range: range.clone(),
2337            excerpts: self.excerpts.cursor(),
2338            excerpt_chunks: None,
2339            language_aware,
2340        };
2341        chunks.seek(range.start);
2342        chunks
2343    }
2344
2345    pub fn offset_to_point(&self, offset: usize) -> Point {
2346        if let Some((_, _, buffer)) = self.as_singleton() {
2347            return buffer.offset_to_point(offset);
2348        }
2349
2350        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2351        cursor.seek(&offset, Bias::Right, &());
2352        if let Some(excerpt) = cursor.item() {
2353            let (start_offset, start_point) = cursor.start();
2354            let overshoot = offset - start_offset;
2355            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2356            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2357            let buffer_point = excerpt
2358                .buffer
2359                .offset_to_point(excerpt_start_offset + overshoot);
2360            *start_point + (buffer_point - excerpt_start_point)
2361        } else {
2362            self.excerpts.summary().text.lines
2363        }
2364    }
2365
2366    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
2367        if let Some((_, _, buffer)) = self.as_singleton() {
2368            return buffer.offset_to_point_utf16(offset);
2369        }
2370
2371        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
2372        cursor.seek(&offset, Bias::Right, &());
2373        if let Some(excerpt) = cursor.item() {
2374            let (start_offset, start_point) = cursor.start();
2375            let overshoot = offset - start_offset;
2376            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2377            let excerpt_start_point = excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2378            let buffer_point = excerpt
2379                .buffer
2380                .offset_to_point_utf16(excerpt_start_offset + overshoot);
2381            *start_point + (buffer_point - excerpt_start_point)
2382        } else {
2383            self.excerpts.summary().text.lines_utf16()
2384        }
2385    }
2386
2387    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
2388        if let Some((_, _, buffer)) = self.as_singleton() {
2389            return buffer.point_to_point_utf16(point);
2390        }
2391
2392        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
2393        cursor.seek(&point, Bias::Right, &());
2394        if let Some(excerpt) = cursor.item() {
2395            let (start_offset, start_point) = cursor.start();
2396            let overshoot = point - start_offset;
2397            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2398            let excerpt_start_point_utf16 =
2399                excerpt.range.context.start.to_point_utf16(&excerpt.buffer);
2400            let buffer_point = excerpt
2401                .buffer
2402                .point_to_point_utf16(excerpt_start_point + overshoot);
2403            *start_point + (buffer_point - excerpt_start_point_utf16)
2404        } else {
2405            self.excerpts.summary().text.lines_utf16()
2406        }
2407    }
2408
2409    pub fn point_to_offset(&self, point: Point) -> usize {
2410        if let Some((_, _, buffer)) = self.as_singleton() {
2411            return buffer.point_to_offset(point);
2412        }
2413
2414        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
2415        cursor.seek(&point, Bias::Right, &());
2416        if let Some(excerpt) = cursor.item() {
2417            let (start_point, start_offset) = cursor.start();
2418            let overshoot = point - start_point;
2419            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2420            let excerpt_start_point = excerpt.range.context.start.to_point(&excerpt.buffer);
2421            let buffer_offset = excerpt
2422                .buffer
2423                .point_to_offset(excerpt_start_point + overshoot);
2424            *start_offset + buffer_offset - excerpt_start_offset
2425        } else {
2426            self.excerpts.summary().text.len
2427        }
2428    }
2429
2430    pub fn offset_utf16_to_offset(&self, offset_utf16: OffsetUtf16) -> usize {
2431        if let Some((_, _, buffer)) = self.as_singleton() {
2432            return buffer.offset_utf16_to_offset(offset_utf16);
2433        }
2434
2435        let mut cursor = self.excerpts.cursor::<(OffsetUtf16, usize)>();
2436        cursor.seek(&offset_utf16, Bias::Right, &());
2437        if let Some(excerpt) = cursor.item() {
2438            let (start_offset_utf16, start_offset) = cursor.start();
2439            let overshoot = offset_utf16 - start_offset_utf16;
2440            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2441            let excerpt_start_offset_utf16 =
2442                excerpt.buffer.offset_to_offset_utf16(excerpt_start_offset);
2443            let buffer_offset = excerpt
2444                .buffer
2445                .offset_utf16_to_offset(excerpt_start_offset_utf16 + overshoot);
2446            *start_offset + (buffer_offset - excerpt_start_offset)
2447        } else {
2448            self.excerpts.summary().text.len
2449        }
2450    }
2451
2452    pub fn offset_to_offset_utf16(&self, offset: usize) -> OffsetUtf16 {
2453        if let Some((_, _, buffer)) = self.as_singleton() {
2454            return buffer.offset_to_offset_utf16(offset);
2455        }
2456
2457        let mut cursor = self.excerpts.cursor::<(usize, OffsetUtf16)>();
2458        cursor.seek(&offset, Bias::Right, &());
2459        if let Some(excerpt) = cursor.item() {
2460            let (start_offset, start_offset_utf16) = cursor.start();
2461            let overshoot = offset - start_offset;
2462            let excerpt_start_offset_utf16 =
2463                excerpt.range.context.start.to_offset_utf16(&excerpt.buffer);
2464            let excerpt_start_offset = excerpt
2465                .buffer
2466                .offset_utf16_to_offset(excerpt_start_offset_utf16);
2467            let buffer_offset_utf16 = excerpt
2468                .buffer
2469                .offset_to_offset_utf16(excerpt_start_offset + overshoot);
2470            *start_offset_utf16 + (buffer_offset_utf16 - excerpt_start_offset_utf16)
2471        } else {
2472            self.excerpts.summary().text.len_utf16
2473        }
2474    }
2475
2476    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
2477        if let Some((_, _, buffer)) = self.as_singleton() {
2478            return buffer.point_utf16_to_offset(point);
2479        }
2480
2481        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
2482        cursor.seek(&point, Bias::Right, &());
2483        if let Some(excerpt) = cursor.item() {
2484            let (start_point, start_offset) = cursor.start();
2485            let overshoot = point - start_point;
2486            let excerpt_start_offset = excerpt.range.context.start.to_offset(&excerpt.buffer);
2487            let excerpt_start_point = excerpt
2488                .buffer
2489                .offset_to_point_utf16(excerpt.range.context.start.to_offset(&excerpt.buffer));
2490            let buffer_offset = excerpt
2491                .buffer
2492                .point_utf16_to_offset(excerpt_start_point + overshoot);
2493            *start_offset + (buffer_offset - excerpt_start_offset)
2494        } else {
2495            self.excerpts.summary().text.len
2496        }
2497    }
2498
2499    pub fn point_to_buffer_offset<T: ToOffset>(
2500        &self,
2501        point: T,
2502    ) -> Option<(&BufferSnapshot, usize)> {
2503        let offset = point.to_offset(self);
2504        let mut cursor = self.excerpts.cursor::<usize>();
2505        cursor.seek(&offset, Bias::Right, &());
2506        if cursor.item().is_none() {
2507            cursor.prev(&());
2508        }
2509
2510        cursor.item().map(|excerpt| {
2511            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2512            let buffer_point = excerpt_start + offset - *cursor.start();
2513            (&excerpt.buffer, buffer_point)
2514        })
2515    }
2516
2517    pub fn suggested_indents(
2518        &self,
2519        rows: impl IntoIterator<Item = u32>,
2520        cx: &AppContext,
2521    ) -> BTreeMap<MultiBufferRow, IndentSize> {
2522        let mut result = BTreeMap::new();
2523
2524        let mut rows_for_excerpt = Vec::new();
2525        let mut cursor = self.excerpts.cursor::<Point>();
2526        let mut rows = rows.into_iter().peekable();
2527        let mut prev_row = u32::MAX;
2528        let mut prev_language_indent_size = IndentSize::default();
2529
2530        while let Some(row) = rows.next() {
2531            cursor.seek(&Point::new(row, 0), Bias::Right, &());
2532            let excerpt = match cursor.item() {
2533                Some(excerpt) => excerpt,
2534                _ => continue,
2535            };
2536
2537            // Retrieve the language and indent size once for each disjoint region being indented.
2538            let single_indent_size = if row.saturating_sub(1) == prev_row {
2539                prev_language_indent_size
2540            } else {
2541                excerpt
2542                    .buffer
2543                    .language_indent_size_at(Point::new(row, 0), cx)
2544            };
2545            prev_language_indent_size = single_indent_size;
2546            prev_row = row;
2547
2548            let start_buffer_row = excerpt.range.context.start.to_point(&excerpt.buffer).row;
2549            let start_multibuffer_row = cursor.start().row;
2550
2551            rows_for_excerpt.push(row);
2552            while let Some(next_row) = rows.peek().copied() {
2553                if cursor.end(&()).row > next_row {
2554                    rows_for_excerpt.push(next_row);
2555                    rows.next();
2556                } else {
2557                    break;
2558                }
2559            }
2560
2561            let buffer_rows = rows_for_excerpt
2562                .drain(..)
2563                .map(|row| start_buffer_row + row - start_multibuffer_row);
2564            let buffer_indents = excerpt
2565                .buffer
2566                .suggested_indents(buffer_rows, single_indent_size);
2567            let multibuffer_indents = buffer_indents.into_iter().map(|(row, indent)| {
2568                (
2569                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
2570                    indent,
2571                )
2572            });
2573            result.extend(multibuffer_indents);
2574        }
2575
2576        result
2577    }
2578
2579    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
2580        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
2581            let mut size = buffer.indent_size_for_line(range.start.row);
2582            size.len = size
2583                .len
2584                .min(range.end.column)
2585                .saturating_sub(range.start.column);
2586            size
2587        } else {
2588            IndentSize::spaces(0)
2589        }
2590    }
2591
2592    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
2593        while row.0 > 0 {
2594            row.0 -= 1;
2595            if !self.is_line_blank(row) {
2596                return Some(row);
2597            }
2598        }
2599        None
2600    }
2601
2602    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
2603        if let Some((_, range)) = self.buffer_line_for_row(row) {
2604            range.end.column - range.start.column
2605        } else {
2606            0
2607        }
2608    }
2609
2610    pub fn buffer_line_for_row(
2611        &self,
2612        row: MultiBufferRow,
2613    ) -> Option<(&BufferSnapshot, Range<Point>)> {
2614        let mut cursor = self.excerpts.cursor::<Point>();
2615        let point = Point::new(row.0, 0);
2616        cursor.seek(&point, Bias::Right, &());
2617        if cursor.item().is_none() && *cursor.start() == point {
2618            cursor.prev(&());
2619        }
2620        if let Some(excerpt) = cursor.item() {
2621            let overshoot = row.0 - cursor.start().row;
2622            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer);
2623            let excerpt_end = excerpt.range.context.end.to_point(&excerpt.buffer);
2624            let buffer_row = excerpt_start.row + overshoot;
2625            let line_start = Point::new(buffer_row, 0);
2626            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
2627            return Some((
2628                &excerpt.buffer,
2629                line_start.max(excerpt_start)..line_end.min(excerpt_end),
2630            ));
2631        }
2632        None
2633    }
2634
2635    pub fn max_point(&self) -> Point {
2636        self.text_summary().lines
2637    }
2638
2639    pub fn text_summary(&self) -> TextSummary {
2640        self.excerpts.summary().text.clone()
2641    }
2642
2643    pub fn text_summary_for_range<D, O>(&self, range: Range<O>) -> D
2644    where
2645        D: TextDimension,
2646        O: ToOffset,
2647    {
2648        let mut summary = D::default();
2649        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
2650        let mut cursor = self.excerpts.cursor::<usize>();
2651        cursor.seek(&range.start, Bias::Right, &());
2652        if let Some(excerpt) = cursor.item() {
2653            let mut end_before_newline = cursor.end(&());
2654            if excerpt.has_trailing_newline {
2655                end_before_newline -= 1;
2656            }
2657
2658            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2659            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
2660            let end_in_excerpt =
2661                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
2662            summary.add_assign(
2663                &excerpt
2664                    .buffer
2665                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
2666            );
2667
2668            if range.end > end_before_newline {
2669                summary.add_assign(&D::from_text_summary(&TextSummary::from("\n")));
2670            }
2671
2672            cursor.next(&());
2673        }
2674
2675        if range.end > *cursor.start() {
2676            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
2677                &range.end,
2678                Bias::Right,
2679                &(),
2680            )));
2681            if let Some(excerpt) = cursor.item() {
2682                range.end = cmp::max(*cursor.start(), range.end);
2683
2684                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2685                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
2686                summary.add_assign(
2687                    &excerpt
2688                        .buffer
2689                        .text_summary_for_range(excerpt_start..end_in_excerpt),
2690                );
2691            }
2692        }
2693
2694        summary
2695    }
2696
2697    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
2698    where
2699        D: TextDimension + Ord + Sub<D, Output = D>,
2700    {
2701        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2702        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
2703
2704        cursor.seek(locator, Bias::Left, &());
2705        if cursor.item().is_none() {
2706            cursor.next(&());
2707        }
2708
2709        let mut position = D::from_text_summary(&cursor.start().text);
2710        if let Some(excerpt) = cursor.item() {
2711            if excerpt.id == anchor.excerpt_id {
2712                let excerpt_buffer_start =
2713                    excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2714                let excerpt_buffer_end = excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2715                let buffer_position = cmp::min(
2716                    excerpt_buffer_end,
2717                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
2718                );
2719                if buffer_position > excerpt_buffer_start {
2720                    position.add_assign(&(buffer_position - excerpt_buffer_start));
2721                }
2722            }
2723        }
2724        position
2725    }
2726
2727    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
2728    where
2729        D: TextDimension + Ord + Sub<D, Output = D>,
2730        I: 'a + IntoIterator<Item = &'a Anchor>,
2731    {
2732        if let Some((_, _, buffer)) = self.as_singleton() {
2733            return buffer
2734                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
2735                .collect();
2736        }
2737
2738        let mut anchors = anchors.into_iter().peekable();
2739        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
2740        let mut summaries = Vec::new();
2741        while let Some(anchor) = anchors.peek() {
2742            let excerpt_id = anchor.excerpt_id;
2743            let excerpt_anchors = iter::from_fn(|| {
2744                let anchor = anchors.peek()?;
2745                if anchor.excerpt_id == excerpt_id {
2746                    Some(&anchors.next().unwrap().text_anchor)
2747                } else {
2748                    None
2749                }
2750            });
2751
2752            let locator = self.excerpt_locator_for_id(excerpt_id);
2753            cursor.seek_forward(locator, Bias::Left, &());
2754            if cursor.item().is_none() {
2755                cursor.next(&());
2756            }
2757
2758            let position = D::from_text_summary(&cursor.start().text);
2759            if let Some(excerpt) = cursor.item() {
2760                if excerpt.id == excerpt_id {
2761                    let excerpt_buffer_start =
2762                        excerpt.range.context.start.summary::<D>(&excerpt.buffer);
2763                    let excerpt_buffer_end =
2764                        excerpt.range.context.end.summary::<D>(&excerpt.buffer);
2765                    summaries.extend(
2766                        excerpt
2767                            .buffer
2768                            .summaries_for_anchors::<D, _>(excerpt_anchors)
2769                            .map(move |summary| {
2770                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
2771                                let mut position = position.clone();
2772                                let excerpt_buffer_start = excerpt_buffer_start.clone();
2773                                if summary > excerpt_buffer_start {
2774                                    position.add_assign(&(summary - excerpt_buffer_start));
2775                                }
2776                                position
2777                            }),
2778                    );
2779                    continue;
2780                }
2781            }
2782
2783            summaries.extend(excerpt_anchors.map(|_| position.clone()));
2784        }
2785
2786        summaries
2787    }
2788
2789    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
2790    where
2791        I: 'a + IntoIterator<Item = &'a Anchor>,
2792    {
2793        let mut anchors = anchors.into_iter().enumerate().peekable();
2794        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2795        cursor.next(&());
2796
2797        let mut result = Vec::new();
2798
2799        while let Some((_, anchor)) = anchors.peek() {
2800            let old_excerpt_id = anchor.excerpt_id;
2801
2802            // Find the location where this anchor's excerpt should be.
2803            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
2804            cursor.seek_forward(&Some(old_locator), Bias::Left, &());
2805
2806            if cursor.item().is_none() {
2807                cursor.next(&());
2808            }
2809
2810            let next_excerpt = cursor.item();
2811            let prev_excerpt = cursor.prev_item();
2812
2813            // Process all of the anchors for this excerpt.
2814            while let Some((_, anchor)) = anchors.peek() {
2815                if anchor.excerpt_id != old_excerpt_id {
2816                    break;
2817                }
2818                let (anchor_ix, anchor) = anchors.next().unwrap();
2819                let mut anchor = *anchor;
2820
2821                // Leave min and max anchors unchanged if invalid or
2822                // if the old excerpt still exists at this location
2823                let mut kept_position = next_excerpt
2824                    .map_or(false, |e| e.id == old_excerpt_id && e.contains(&anchor))
2825                    || old_excerpt_id == ExcerptId::max()
2826                    || old_excerpt_id == ExcerptId::min();
2827
2828                // If the old excerpt no longer exists at this location, then attempt to
2829                // find an equivalent position for this anchor in an adjacent excerpt.
2830                if !kept_position {
2831                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
2832                        if excerpt.contains(&anchor) {
2833                            anchor.excerpt_id = excerpt.id;
2834                            kept_position = true;
2835                            break;
2836                        }
2837                    }
2838                }
2839
2840                // If there's no adjacent excerpt that contains the anchor's position,
2841                // then report that the anchor has lost its position.
2842                if !kept_position {
2843                    anchor = if let Some(excerpt) = next_excerpt {
2844                        let mut text_anchor = excerpt
2845                            .range
2846                            .context
2847                            .start
2848                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2849                        if text_anchor
2850                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
2851                            .is_gt()
2852                        {
2853                            text_anchor = excerpt.range.context.end;
2854                        }
2855                        Anchor {
2856                            buffer_id: Some(excerpt.buffer_id),
2857                            excerpt_id: excerpt.id,
2858                            text_anchor,
2859                        }
2860                    } else if let Some(excerpt) = prev_excerpt {
2861                        let mut text_anchor = excerpt
2862                            .range
2863                            .context
2864                            .end
2865                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2866                        if text_anchor
2867                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
2868                            .is_lt()
2869                        {
2870                            text_anchor = excerpt.range.context.start;
2871                        }
2872                        Anchor {
2873                            buffer_id: Some(excerpt.buffer_id),
2874                            excerpt_id: excerpt.id,
2875                            text_anchor,
2876                        }
2877                    } else if anchor.text_anchor.bias == Bias::Left {
2878                        Anchor::min()
2879                    } else {
2880                        Anchor::max()
2881                    };
2882                }
2883
2884                result.push((anchor_ix, anchor, kept_position));
2885            }
2886        }
2887        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
2888        result
2889    }
2890
2891    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2892        self.anchor_at(position, Bias::Left)
2893    }
2894
2895    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2896        self.anchor_at(position, Bias::Right)
2897    }
2898
2899    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
2900        let offset = position.to_offset(self);
2901        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
2902            return Anchor {
2903                buffer_id: Some(buffer_id),
2904                excerpt_id: *excerpt_id,
2905                text_anchor: buffer.anchor_at(offset, bias),
2906            };
2907        }
2908
2909        let mut cursor = self.excerpts.cursor::<(usize, Option<ExcerptId>)>();
2910        cursor.seek(&offset, Bias::Right, &());
2911        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
2912            cursor.prev(&());
2913        }
2914        if let Some(excerpt) = cursor.item() {
2915            let mut overshoot = offset.saturating_sub(cursor.start().0);
2916            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
2917                overshoot -= 1;
2918                bias = Bias::Right;
2919            }
2920
2921            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
2922            let text_anchor =
2923                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
2924            Anchor {
2925                buffer_id: Some(excerpt.buffer_id),
2926                excerpt_id: excerpt.id,
2927                text_anchor,
2928            }
2929        } else if offset == 0 && bias == Bias::Left {
2930            Anchor::min()
2931        } else {
2932            Anchor::max()
2933        }
2934    }
2935
2936    /// Returns an anchor for the given excerpt and text anchor,
2937    /// returns None if the excerpt_id is no longer valid.
2938    pub fn anchor_in_excerpt(
2939        &self,
2940        excerpt_id: ExcerptId,
2941        text_anchor: text::Anchor,
2942    ) -> Option<Anchor> {
2943        let locator = self.excerpt_locator_for_id(excerpt_id);
2944        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
2945        cursor.seek(locator, Bias::Left, &());
2946        if let Some(excerpt) = cursor.item() {
2947            if excerpt.id == excerpt_id {
2948                let text_anchor = excerpt.clip_anchor(text_anchor);
2949                drop(cursor);
2950                return Some(Anchor {
2951                    buffer_id: Some(excerpt.buffer_id),
2952                    excerpt_id,
2953                    text_anchor,
2954                });
2955            }
2956        }
2957        None
2958    }
2959
2960    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2961        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
2962            true
2963        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
2964            excerpt.buffer.can_resolve(&anchor.text_anchor)
2965        } else {
2966            false
2967        }
2968    }
2969
2970    pub fn excerpts(
2971        &self,
2972    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
2973        self.excerpts
2974            .iter()
2975            .map(|excerpt| (excerpt.id, &excerpt.buffer, excerpt.range.clone()))
2976    }
2977
2978    fn excerpts_for_range<T: ToOffset>(
2979        &self,
2980        range: Range<T>,
2981    ) -> impl Iterator<Item = (&Excerpt, usize)> + '_ {
2982        let range = range.start.to_offset(self)..range.end.to_offset(self);
2983
2984        let mut cursor = self.excerpts.cursor::<usize>();
2985        cursor.seek(&range.start, Bias::Right, &());
2986        cursor.prev(&());
2987
2988        iter::from_fn(move || {
2989            cursor.next(&());
2990            if cursor.start() < &range.end {
2991                cursor.item().map(|item| (item, *cursor.start()))
2992            } else {
2993                None
2994            }
2995        })
2996    }
2997
2998    pub fn excerpt_boundaries_in_range<R, T>(
2999        &self,
3000        range: R,
3001    ) -> impl Iterator<Item = ExcerptBoundary> + '_
3002    where
3003        R: RangeBounds<T>,
3004        T: ToOffset,
3005    {
3006        let start_offset;
3007        let start = match range.start_bound() {
3008            Bound::Included(start) => {
3009                start_offset = start.to_offset(self);
3010                Bound::Included(start_offset)
3011            }
3012            Bound::Excluded(start) => {
3013                start_offset = start.to_offset(self);
3014                Bound::Excluded(start_offset)
3015            }
3016            Bound::Unbounded => {
3017                start_offset = 0;
3018                Bound::Unbounded
3019            }
3020        };
3021        let end = match range.end_bound() {
3022            Bound::Included(end) => Bound::Included(end.to_offset(self)),
3023            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
3024            Bound::Unbounded => Bound::Unbounded,
3025        };
3026        let bounds = (start, end);
3027
3028        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
3029        cursor.seek(&start_offset, Bias::Right, &());
3030        if cursor.item().is_none() {
3031            cursor.prev(&());
3032        }
3033        if !bounds.contains(&cursor.start().0) {
3034            cursor.next(&());
3035        }
3036
3037        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
3038        std::iter::from_fn(move || {
3039            if self.singleton {
3040                None
3041            } else if bounds.contains(&cursor.start().0) {
3042                let excerpt = cursor.item()?;
3043                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
3044                let boundary = ExcerptBoundary {
3045                    id: excerpt.id,
3046                    row: MultiBufferRow(cursor.start().1.row),
3047                    buffer: excerpt.buffer.clone(),
3048                    range: excerpt.range.clone(),
3049                    starts_new_buffer,
3050                };
3051
3052                prev_buffer_id = Some(excerpt.buffer_id);
3053                cursor.next(&());
3054                Some(boundary)
3055            } else {
3056                None
3057            }
3058        })
3059    }
3060
3061    pub fn edit_count(&self) -> usize {
3062        self.edit_count
3063    }
3064
3065    pub fn parse_count(&self) -> usize {
3066        self.parse_count
3067    }
3068
3069    /// Returns the smallest enclosing bracket ranges containing the given range or
3070    /// None if no brackets contain range or the range is not contained in a single
3071    /// excerpt
3072    ///
3073    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
3074    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
3075        &self,
3076        range: Range<T>,
3077        range_filter: Option<&dyn Fn(Range<usize>, Range<usize>) -> bool>,
3078    ) -> Option<(Range<usize>, Range<usize>)> {
3079        let range = range.start.to_offset(self)..range.end.to_offset(self);
3080        let excerpt = self.excerpt_containing(range.clone())?;
3081
3082        // Filter to ranges contained in the excerpt
3083        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
3084            excerpt.contains_buffer_range(open.start..close.end)
3085                && range_filter.map_or(true, |filter| {
3086                    filter(
3087                        excerpt.map_range_from_buffer(open),
3088                        excerpt.map_range_from_buffer(close),
3089                    )
3090                })
3091        };
3092
3093        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
3094            excerpt.map_range_to_buffer(range),
3095            Some(&range_filter),
3096        )?;
3097
3098        Some((
3099            excerpt.map_range_from_buffer(open),
3100            excerpt.map_range_from_buffer(close),
3101        ))
3102    }
3103
3104    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
3105    /// not contained in a single excerpt
3106    pub fn enclosing_bracket_ranges<T: ToOffset>(
3107        &self,
3108        range: Range<T>,
3109    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3110        let range = range.start.to_offset(self)..range.end.to_offset(self);
3111        let excerpt = self.excerpt_containing(range.clone())?;
3112
3113        Some(
3114            excerpt
3115                .buffer()
3116                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
3117                .filter_map(move |(open, close)| {
3118                    if excerpt.contains_buffer_range(open.start..close.end) {
3119                        Some((
3120                            excerpt.map_range_from_buffer(open),
3121                            excerpt.map_range_from_buffer(close),
3122                        ))
3123                    } else {
3124                        None
3125                    }
3126                }),
3127        )
3128    }
3129
3130    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
3131    /// not contained in a single excerpt
3132    pub fn bracket_ranges<T: ToOffset>(
3133        &self,
3134        range: Range<T>,
3135    ) -> Option<impl Iterator<Item = (Range<usize>, Range<usize>)> + '_> {
3136        let range = range.start.to_offset(self)..range.end.to_offset(self);
3137        let excerpt = self.excerpt_containing(range.clone())?;
3138
3139        Some(
3140            excerpt
3141                .buffer()
3142                .bracket_ranges(excerpt.map_range_to_buffer(range))
3143                .filter_map(move |(start_bracket_range, close_bracket_range)| {
3144                    let buffer_range = start_bracket_range.start..close_bracket_range.end;
3145                    if excerpt.contains_buffer_range(buffer_range) {
3146                        Some((
3147                            excerpt.map_range_from_buffer(start_bracket_range),
3148                            excerpt.map_range_from_buffer(close_bracket_range),
3149                        ))
3150                    } else {
3151                        None
3152                    }
3153                }),
3154        )
3155    }
3156
3157    pub fn redacted_ranges<'a, T: ToOffset>(
3158        &'a self,
3159        range: Range<T>,
3160        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
3161    ) -> impl Iterator<Item = Range<usize>> + 'a {
3162        let range = range.start.to_offset(self)..range.end.to_offset(self);
3163        self.excerpts_for_range(range.clone())
3164            .filter_map(move |(excerpt, excerpt_offset)| {
3165                redaction_enabled(excerpt.buffer.file()).then(move || {
3166                    let excerpt_buffer_start =
3167                        excerpt.range.context.start.to_offset(&excerpt.buffer);
3168
3169                    excerpt
3170                        .buffer
3171                        .redacted_ranges(excerpt.range.context.clone())
3172                        .map(move |mut redacted_range| {
3173                            // Re-base onto the excerpts coordinates in the multibuffer
3174                            redacted_range.start = excerpt_offset
3175                                + redacted_range.start.saturating_sub(excerpt_buffer_start);
3176                            redacted_range.end = excerpt_offset
3177                                + redacted_range.end.saturating_sub(excerpt_buffer_start);
3178
3179                            redacted_range
3180                        })
3181                        .skip_while(move |redacted_range| redacted_range.end < range.start)
3182                        .take_while(move |redacted_range| redacted_range.start < range.end)
3183                })
3184            })
3185            .flatten()
3186    }
3187
3188    pub fn runnable_ranges(
3189        &self,
3190        range: Range<Anchor>,
3191    ) -> impl Iterator<Item = language::RunnableRange> + '_ {
3192        let range = range.start.to_offset(self)..range.end.to_offset(self);
3193        self.excerpts_for_range(range.clone())
3194            .flat_map(move |(excerpt, excerpt_offset)| {
3195                let excerpt_buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
3196
3197                excerpt
3198                    .buffer
3199                    .runnable_ranges(excerpt.range.context.clone())
3200                    .filter_map(move |mut runnable| {
3201                        // Re-base onto the excerpts coordinates in the multibuffer
3202                        //
3203                        // The node matching our runnables query might partially overlap with
3204                        // the provided range. If the run indicator is outside of excerpt bounds, do not actually show it.
3205                        if runnable.run_range.start < excerpt_buffer_start {
3206                            return None;
3207                        }
3208                        if language::ToPoint::to_point(&runnable.run_range.end, &excerpt.buffer).row
3209                            > excerpt.max_buffer_row
3210                        {
3211                            return None;
3212                        }
3213                        runnable.run_range.start =
3214                            excerpt_offset + runnable.run_range.start - excerpt_buffer_start;
3215                        runnable.run_range.end =
3216                            excerpt_offset + runnable.run_range.end - excerpt_buffer_start;
3217                        Some(runnable)
3218                    })
3219                    .skip_while(move |runnable| runnable.run_range.end < range.start)
3220                    .take_while(move |runnable| runnable.run_range.start < range.end)
3221            })
3222    }
3223
3224    pub fn diagnostics_update_count(&self) -> usize {
3225        self.diagnostics_update_count
3226    }
3227
3228    pub fn git_diff_update_count(&self) -> usize {
3229        self.git_diff_update_count
3230    }
3231
3232    pub fn trailing_excerpt_update_count(&self) -> usize {
3233        self.trailing_excerpt_update_count
3234    }
3235
3236    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
3237        self.point_to_buffer_offset(point)
3238            .and_then(|(buffer, _)| buffer.file())
3239    }
3240
3241    pub fn language_at<T: ToOffset>(&self, point: T) -> Option<&Arc<Language>> {
3242        self.point_to_buffer_offset(point)
3243            .and_then(|(buffer, offset)| buffer.language_at(offset))
3244    }
3245
3246    pub fn settings_at<'a, T: ToOffset>(
3247        &'a self,
3248        point: T,
3249        cx: &'a AppContext,
3250    ) -> &'a LanguageSettings {
3251        let mut language = None;
3252        let mut file = None;
3253        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
3254            language = buffer.language_at(offset);
3255            file = buffer.file();
3256        }
3257        language_settings(language, file, cx)
3258    }
3259
3260    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
3261        self.point_to_buffer_offset(point)
3262            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
3263    }
3264
3265    pub fn language_indent_size_at<T: ToOffset>(
3266        &self,
3267        position: T,
3268        cx: &AppContext,
3269    ) -> Option<IndentSize> {
3270        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
3271        Some(buffer_snapshot.language_indent_size_at(offset, cx))
3272    }
3273
3274    pub fn is_dirty(&self) -> bool {
3275        self.is_dirty
3276    }
3277
3278    pub fn has_conflict(&self) -> bool {
3279        self.has_conflict
3280    }
3281
3282    pub fn has_diagnostics(&self) -> bool {
3283        self.excerpts
3284            .iter()
3285            .any(|excerpt| excerpt.buffer.has_diagnostics())
3286    }
3287
3288    pub fn diagnostic_group<'a, O>(
3289        &'a self,
3290        group_id: usize,
3291    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3292    where
3293        O: text::FromAnchor + 'a,
3294    {
3295        self.as_singleton()
3296            .into_iter()
3297            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
3298    }
3299
3300    pub fn diagnostics_in_range<'a, T, O>(
3301        &'a self,
3302        range: Range<T>,
3303        reversed: bool,
3304    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
3305    where
3306        T: 'a + ToOffset,
3307        O: 'a + text::FromAnchor + Ord,
3308    {
3309        self.as_singleton()
3310            .into_iter()
3311            .flat_map(move |(_, _, buffer)| {
3312                buffer.diagnostics_in_range(
3313                    range.start.to_offset(self)..range.end.to_offset(self),
3314                    reversed,
3315                )
3316            })
3317    }
3318
3319    pub fn has_git_diffs(&self) -> bool {
3320        for excerpt in self.excerpts.iter() {
3321            if excerpt.buffer.has_git_diff() {
3322                return true;
3323            }
3324        }
3325        false
3326    }
3327
3328    pub fn git_diff_hunks_in_range_rev(
3329        &self,
3330        row_range: Range<MultiBufferRow>,
3331    ) -> impl Iterator<Item = DiffHunk<MultiBufferRow>> + '_ {
3332        let mut cursor = self.excerpts.cursor::<Point>();
3333
3334        cursor.seek(&Point::new(row_range.end.0, 0), Bias::Left, &());
3335        if cursor.item().is_none() {
3336            cursor.prev(&());
3337        }
3338
3339        std::iter::from_fn(move || {
3340            let excerpt = cursor.item()?;
3341            let multibuffer_start = *cursor.start();
3342            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3343            if multibuffer_start.row >= row_range.end.0 {
3344                return None;
3345            }
3346
3347            let mut buffer_start = excerpt.range.context.start;
3348            let mut buffer_end = excerpt.range.context.end;
3349            let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3350            let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3351
3352            if row_range.start.0 > multibuffer_start.row {
3353                let buffer_start_point =
3354                    excerpt_start_point + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3355                buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3356            }
3357
3358            if row_range.end.0 < multibuffer_end.row {
3359                let buffer_end_point =
3360                    excerpt_start_point + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3361                buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3362            }
3363
3364            let buffer_hunks = excerpt
3365                .buffer
3366                .git_diff_hunks_intersecting_range_rev(buffer_start..buffer_end)
3367                .map(move |hunk| {
3368                    let start = multibuffer_start.row
3369                        + hunk
3370                            .associated_range
3371                            .start
3372                            .saturating_sub(excerpt_start_point.row);
3373                    let end = multibuffer_start.row
3374                        + hunk
3375                            .associated_range
3376                            .end
3377                            .min(excerpt_end_point.row + 1)
3378                            .saturating_sub(excerpt_start_point.row);
3379
3380                    DiffHunk {
3381                        associated_range: MultiBufferRow(start)..MultiBufferRow(end),
3382                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3383                        buffer_range: hunk.buffer_range.clone(),
3384                        buffer_id: hunk.buffer_id,
3385                    }
3386                });
3387
3388            cursor.prev(&());
3389
3390            Some(buffer_hunks)
3391        })
3392        .flatten()
3393    }
3394
3395    pub fn git_diff_hunks_in_range(
3396        &self,
3397        row_range: Range<MultiBufferRow>,
3398    ) -> impl Iterator<Item = DiffHunk<MultiBufferRow>> + '_ {
3399        let mut cursor = self.excerpts.cursor::<Point>();
3400
3401        cursor.seek(&Point::new(row_range.start.0, 0), Bias::Left, &());
3402
3403        std::iter::from_fn(move || {
3404            let excerpt = cursor.item()?;
3405            let multibuffer_start = *cursor.start();
3406            let multibuffer_end = multibuffer_start + excerpt.text_summary.lines;
3407            let mut buffer_start = excerpt.range.context.start;
3408            let mut buffer_end = excerpt.range.context.end;
3409
3410            let excerpt_rows = match multibuffer_start.row.cmp(&row_range.end.0) {
3411                cmp::Ordering::Less => {
3412                    let excerpt_start_point = buffer_start.to_point(&excerpt.buffer);
3413                    let excerpt_end_point = excerpt_start_point + excerpt.text_summary.lines;
3414
3415                    if row_range.start.0 > multibuffer_start.row {
3416                        let buffer_start_point = excerpt_start_point
3417                            + Point::new(row_range.start.0 - multibuffer_start.row, 0);
3418                        buffer_start = excerpt.buffer.anchor_before(buffer_start_point);
3419                    }
3420
3421                    if row_range.end.0 < multibuffer_end.row {
3422                        let buffer_end_point = excerpt_start_point
3423                            + Point::new(row_range.end.0 - multibuffer_start.row, 0);
3424                        buffer_end = excerpt.buffer.anchor_before(buffer_end_point);
3425                    }
3426                    excerpt_start_point.row..excerpt_end_point.row
3427                }
3428                cmp::Ordering::Equal if row_range.end.0 == 0 => {
3429                    buffer_end = buffer_start;
3430                    0..0
3431                }
3432                cmp::Ordering::Greater | cmp::Ordering::Equal => return None,
3433            };
3434
3435            let buffer_hunks = excerpt
3436                .buffer
3437                .git_diff_hunks_intersecting_range(buffer_start..buffer_end)
3438                .map(move |hunk| {
3439                    let buffer_range = if excerpt_rows.start == 0 && excerpt_rows.end == 0 {
3440                        MultiBufferRow(0)..MultiBufferRow(1)
3441                    } else {
3442                        let start = multibuffer_start.row
3443                            + hunk
3444                                .associated_range
3445                                .start
3446                                .saturating_sub(excerpt_rows.start);
3447                        let end = multibuffer_start.row
3448                            + hunk
3449                                .associated_range
3450                                .end
3451                                .min(excerpt_rows.end + 1)
3452                                .saturating_sub(excerpt_rows.start);
3453                        MultiBufferRow(start)..MultiBufferRow(end)
3454                    };
3455                    DiffHunk {
3456                        associated_range: buffer_range,
3457                        diff_base_byte_range: hunk.diff_base_byte_range.clone(),
3458                        buffer_range: hunk.buffer_range.clone(),
3459                        buffer_id: hunk.buffer_id,
3460                    }
3461                });
3462
3463            cursor.next(&());
3464
3465            Some(buffer_hunks)
3466        })
3467        .flatten()
3468    }
3469
3470    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
3471        let range = range.start.to_offset(self)..range.end.to_offset(self);
3472        let excerpt = self.excerpt_containing(range.clone())?;
3473
3474        let ancestor_buffer_range = excerpt
3475            .buffer()
3476            .range_for_syntax_ancestor(excerpt.map_range_to_buffer(range))?;
3477
3478        Some(excerpt.map_range_from_buffer(ancestor_buffer_range))
3479    }
3480
3481    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
3482        let (excerpt_id, _, buffer) = self.as_singleton()?;
3483        let outline = buffer.outline(theme)?;
3484        Some(Outline::new(
3485            outline
3486                .items
3487                .into_iter()
3488                .flat_map(|item| {
3489                    Some(OutlineItem {
3490                        depth: item.depth,
3491                        range: self.anchor_in_excerpt(*excerpt_id, item.range.start)?
3492                            ..self.anchor_in_excerpt(*excerpt_id, item.range.end)?,
3493                        text: item.text,
3494                        highlight_ranges: item.highlight_ranges,
3495                        name_ranges: item.name_ranges,
3496                    })
3497                })
3498                .collect(),
3499        ))
3500    }
3501
3502    pub fn symbols_containing<T: ToOffset>(
3503        &self,
3504        offset: T,
3505        theme: Option<&SyntaxTheme>,
3506    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
3507        let anchor = self.anchor_before(offset);
3508        let excerpt_id = anchor.excerpt_id;
3509        let excerpt = self.excerpt(excerpt_id)?;
3510        Some((
3511            excerpt.buffer_id,
3512            excerpt
3513                .buffer
3514                .symbols_containing(anchor.text_anchor, theme)
3515                .into_iter()
3516                .flatten()
3517                .flat_map(|item| {
3518                    Some(OutlineItem {
3519                        depth: item.depth,
3520                        range: self.anchor_in_excerpt(excerpt_id, item.range.start)?
3521                            ..self.anchor_in_excerpt(excerpt_id, item.range.end)?,
3522                        text: item.text,
3523                        highlight_ranges: item.highlight_ranges,
3524                        name_ranges: item.name_ranges,
3525                    })
3526                })
3527                .collect(),
3528        ))
3529    }
3530
3531    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
3532        if id == ExcerptId::min() {
3533            Locator::min_ref()
3534        } else if id == ExcerptId::max() {
3535            Locator::max_ref()
3536        } else {
3537            let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
3538            cursor.seek(&id, Bias::Left, &());
3539            if let Some(entry) = cursor.item() {
3540                if entry.id == id {
3541                    return &entry.locator;
3542                }
3543            }
3544            panic!("invalid excerpt id {:?}", id)
3545        }
3546    }
3547
3548    // Returns the locators referenced by the given excerpt ids, sorted by locator.
3549    fn excerpt_locators_for_ids(
3550        &self,
3551        ids: impl IntoIterator<Item = ExcerptId>,
3552    ) -> SmallVec<[Locator; 1]> {
3553        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
3554        sorted_ids.sort_unstable();
3555        let mut locators = SmallVec::new();
3556
3557        while sorted_ids.last() == Some(&ExcerptId::max()) {
3558            sorted_ids.pop();
3559            locators.push(Locator::max());
3560        }
3561
3562        let mut sorted_ids = sorted_ids.into_iter().dedup().peekable();
3563        if sorted_ids.peek() == Some(&ExcerptId::min()) {
3564            sorted_ids.next();
3565            locators.push(Locator::min());
3566        }
3567
3568        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>();
3569        for id in sorted_ids {
3570            if cursor.seek_forward(&id, Bias::Left, &()) {
3571                locators.push(cursor.item().unwrap().locator.clone());
3572            } else {
3573                panic!("invalid excerpt id {:?}", id);
3574            }
3575        }
3576
3577        locators.sort_unstable();
3578        locators
3579    }
3580
3581    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
3582        Some(self.excerpt(excerpt_id)?.buffer_id)
3583    }
3584
3585    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
3586        Some(&self.excerpt(excerpt_id)?.buffer)
3587    }
3588
3589    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
3590        let mut cursor = self.excerpts.cursor::<Option<&Locator>>();
3591        let locator = self.excerpt_locator_for_id(excerpt_id);
3592        cursor.seek(&Some(locator), Bias::Left, &());
3593        if let Some(excerpt) = cursor.item() {
3594            if excerpt.id == excerpt_id {
3595                return Some(excerpt);
3596            }
3597        }
3598        None
3599    }
3600
3601    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
3602    pub fn excerpt_containing<T: ToOffset>(&self, range: Range<T>) -> Option<MultiBufferExcerpt> {
3603        let range = range.start.to_offset(self)..range.end.to_offset(self);
3604
3605        let mut cursor = self.excerpts.cursor::<usize>();
3606        cursor.seek(&range.start, Bias::Right, &());
3607        let start_excerpt = cursor.item()?;
3608
3609        if range.start == range.end {
3610            return Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()));
3611        }
3612
3613        cursor.seek(&range.end, Bias::Right, &());
3614        let end_excerpt = cursor.item()?;
3615
3616        if start_excerpt.id == end_excerpt.id {
3617            Some(MultiBufferExcerpt::new(start_excerpt, *cursor.start()))
3618        } else {
3619            None
3620        }
3621    }
3622
3623    pub fn remote_selections_in_range<'a>(
3624        &'a self,
3625        range: &'a Range<Anchor>,
3626    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
3627        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
3628        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
3629        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
3630        cursor.seek(start_locator, Bias::Left, &());
3631        cursor
3632            .take_while(move |excerpt| excerpt.locator <= *end_locator)
3633            .flat_map(move |excerpt| {
3634                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
3635                if excerpt.id == range.start.excerpt_id {
3636                    query_range.start = range.start.text_anchor;
3637                }
3638                if excerpt.id == range.end.excerpt_id {
3639                    query_range.end = range.end.text_anchor;
3640                }
3641
3642                excerpt
3643                    .buffer
3644                    .remote_selections_in_range(query_range)
3645                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
3646                        selections.map(move |selection| {
3647                            let mut start = Anchor {
3648                                buffer_id: Some(excerpt.buffer_id),
3649                                excerpt_id: excerpt.id,
3650                                text_anchor: selection.start,
3651                            };
3652                            let mut end = Anchor {
3653                                buffer_id: Some(excerpt.buffer_id),
3654                                excerpt_id: excerpt.id,
3655                                text_anchor: selection.end,
3656                            };
3657                            if range.start.cmp(&start, self).is_gt() {
3658                                start = range.start;
3659                            }
3660                            if range.end.cmp(&end, self).is_lt() {
3661                                end = range.end;
3662                            }
3663
3664                            (
3665                                replica_id,
3666                                line_mode,
3667                                cursor_shape,
3668                                Selection {
3669                                    id: selection.id,
3670                                    start,
3671                                    end,
3672                                    reversed: selection.reversed,
3673                                    goal: selection.goal,
3674                                },
3675                            )
3676                        })
3677                    })
3678            })
3679    }
3680
3681    pub fn show_headers(&self) -> bool {
3682        self.show_headers
3683    }
3684}
3685
3686#[cfg(any(test, feature = "test-support"))]
3687impl MultiBufferSnapshot {
3688    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
3689        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
3690        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
3691        start..end
3692    }
3693}
3694
3695impl History {
3696    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
3697        self.transaction_depth += 1;
3698        if self.transaction_depth == 1 {
3699            let id = self.next_transaction_id.tick();
3700            self.undo_stack.push(Transaction {
3701                id,
3702                buffer_transactions: Default::default(),
3703                first_edit_at: now,
3704                last_edit_at: now,
3705                suppress_grouping: false,
3706            });
3707            Some(id)
3708        } else {
3709            None
3710        }
3711    }
3712
3713    fn end_transaction(
3714        &mut self,
3715        now: Instant,
3716        buffer_transactions: HashMap<BufferId, TransactionId>,
3717    ) -> bool {
3718        assert_ne!(self.transaction_depth, 0);
3719        self.transaction_depth -= 1;
3720        if self.transaction_depth == 0 {
3721            if buffer_transactions.is_empty() {
3722                self.undo_stack.pop();
3723                false
3724            } else {
3725                self.redo_stack.clear();
3726                let transaction = self.undo_stack.last_mut().unwrap();
3727                transaction.last_edit_at = now;
3728                for (buffer_id, transaction_id) in buffer_transactions {
3729                    transaction
3730                        .buffer_transactions
3731                        .entry(buffer_id)
3732                        .or_insert(transaction_id);
3733                }
3734                true
3735            }
3736        } else {
3737            false
3738        }
3739    }
3740
3741    fn push_transaction<'a, T>(
3742        &mut self,
3743        buffer_transactions: T,
3744        now: Instant,
3745        cx: &mut ModelContext<MultiBuffer>,
3746    ) where
3747        T: IntoIterator<Item = (&'a Model<Buffer>, &'a language::Transaction)>,
3748    {
3749        assert_eq!(self.transaction_depth, 0);
3750        let transaction = Transaction {
3751            id: self.next_transaction_id.tick(),
3752            buffer_transactions: buffer_transactions
3753                .into_iter()
3754                .map(|(buffer, transaction)| (buffer.read(cx).remote_id(), transaction.id))
3755                .collect(),
3756            first_edit_at: now,
3757            last_edit_at: now,
3758            suppress_grouping: false,
3759        };
3760        if !transaction.buffer_transactions.is_empty() {
3761            self.undo_stack.push(transaction);
3762            self.redo_stack.clear();
3763        }
3764    }
3765
3766    fn finalize_last_transaction(&mut self) {
3767        if let Some(transaction) = self.undo_stack.last_mut() {
3768            transaction.suppress_grouping = true;
3769        }
3770    }
3771
3772    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
3773        if let Some(ix) = self
3774            .undo_stack
3775            .iter()
3776            .rposition(|transaction| transaction.id == transaction_id)
3777        {
3778            Some(self.undo_stack.remove(ix))
3779        } else if let Some(ix) = self
3780            .redo_stack
3781            .iter()
3782            .rposition(|transaction| transaction.id == transaction_id)
3783        {
3784            Some(self.redo_stack.remove(ix))
3785        } else {
3786            None
3787        }
3788    }
3789
3790    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
3791        self.undo_stack
3792            .iter_mut()
3793            .find(|transaction| transaction.id == transaction_id)
3794            .or_else(|| {
3795                self.redo_stack
3796                    .iter_mut()
3797                    .find(|transaction| transaction.id == transaction_id)
3798            })
3799    }
3800
3801    fn pop_undo(&mut self) -> Option<&mut Transaction> {
3802        assert_eq!(self.transaction_depth, 0);
3803        if let Some(transaction) = self.undo_stack.pop() {
3804            self.redo_stack.push(transaction);
3805            self.redo_stack.last_mut()
3806        } else {
3807            None
3808        }
3809    }
3810
3811    fn pop_redo(&mut self) -> Option<&mut Transaction> {
3812        assert_eq!(self.transaction_depth, 0);
3813        if let Some(transaction) = self.redo_stack.pop() {
3814            self.undo_stack.push(transaction);
3815            self.undo_stack.last_mut()
3816        } else {
3817            None
3818        }
3819    }
3820
3821    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
3822        let ix = self
3823            .undo_stack
3824            .iter()
3825            .rposition(|transaction| transaction.id == transaction_id)?;
3826        let transaction = self.undo_stack.remove(ix);
3827        self.redo_stack.push(transaction);
3828        self.redo_stack.last()
3829    }
3830
3831    fn group(&mut self) -> Option<TransactionId> {
3832        let mut count = 0;
3833        let mut transactions = self.undo_stack.iter();
3834        if let Some(mut transaction) = transactions.next_back() {
3835            while let Some(prev_transaction) = transactions.next_back() {
3836                if !prev_transaction.suppress_grouping
3837                    && transaction.first_edit_at - prev_transaction.last_edit_at
3838                        <= self.group_interval
3839                {
3840                    transaction = prev_transaction;
3841                    count += 1;
3842                } else {
3843                    break;
3844                }
3845            }
3846        }
3847        self.group_trailing(count)
3848    }
3849
3850    fn group_until(&mut self, transaction_id: TransactionId) {
3851        let mut count = 0;
3852        for transaction in self.undo_stack.iter().rev() {
3853            if transaction.id == transaction_id {
3854                self.group_trailing(count);
3855                break;
3856            } else if transaction.suppress_grouping {
3857                break;
3858            } else {
3859                count += 1;
3860            }
3861        }
3862    }
3863
3864    fn group_trailing(&mut self, n: usize) -> Option<TransactionId> {
3865        let new_len = self.undo_stack.len() - n;
3866        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
3867        if let Some(last_transaction) = transactions_to_keep.last_mut() {
3868            if let Some(transaction) = transactions_to_merge.last() {
3869                last_transaction.last_edit_at = transaction.last_edit_at;
3870            }
3871            for to_merge in transactions_to_merge {
3872                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
3873                    last_transaction
3874                        .buffer_transactions
3875                        .entry(*buffer_id)
3876                        .or_insert(*transaction_id);
3877                }
3878            }
3879        }
3880
3881        self.undo_stack.truncate(new_len);
3882        self.undo_stack.last().map(|t| t.id)
3883    }
3884}
3885
3886impl Excerpt {
3887    fn new(
3888        id: ExcerptId,
3889        locator: Locator,
3890        buffer_id: BufferId,
3891        buffer: BufferSnapshot,
3892        range: ExcerptRange<text::Anchor>,
3893        has_trailing_newline: bool,
3894    ) -> Self {
3895        Excerpt {
3896            id,
3897            locator,
3898            max_buffer_row: range.context.end.to_point(&buffer).row,
3899            text_summary: buffer
3900                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
3901            buffer_id,
3902            buffer,
3903            range,
3904            has_trailing_newline,
3905        }
3906    }
3907
3908    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks {
3909        let content_start = self.range.context.start.to_offset(&self.buffer);
3910        let chunks_start = content_start + range.start;
3911        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
3912
3913        let footer_height = if self.has_trailing_newline
3914            && range.start <= self.text_summary.len
3915            && range.end > self.text_summary.len
3916        {
3917            1
3918        } else {
3919            0
3920        };
3921
3922        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
3923
3924        ExcerptChunks {
3925            content_chunks,
3926            footer_height,
3927        }
3928    }
3929
3930    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3931        let content_start = self.range.context.start.to_offset(&self.buffer);
3932        let bytes_start = content_start + range.start;
3933        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3934        let footer_height = if self.has_trailing_newline
3935            && range.start <= self.text_summary.len
3936            && range.end > self.text_summary.len
3937        {
3938            1
3939        } else {
3940            0
3941        };
3942        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
3943
3944        ExcerptBytes {
3945            content_bytes,
3946            padding_height: footer_height,
3947            reversed: false,
3948        }
3949    }
3950
3951    fn reversed_bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
3952        let content_start = self.range.context.start.to_offset(&self.buffer);
3953        let bytes_start = content_start + range.start;
3954        let bytes_end = content_start + cmp::min(range.end, self.text_summary.len);
3955        let footer_height = if self.has_trailing_newline
3956            && range.start <= self.text_summary.len
3957            && range.end > self.text_summary.len
3958        {
3959            1
3960        } else {
3961            0
3962        };
3963        let content_bytes = self.buffer.reversed_bytes_in_range(bytes_start..bytes_end);
3964
3965        ExcerptBytes {
3966            content_bytes,
3967            padding_height: footer_height,
3968            reversed: true,
3969        }
3970    }
3971
3972    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
3973        if text_anchor
3974            .cmp(&self.range.context.start, &self.buffer)
3975            .is_lt()
3976        {
3977            self.range.context.start
3978        } else if text_anchor
3979            .cmp(&self.range.context.end, &self.buffer)
3980            .is_gt()
3981        {
3982            self.range.context.end
3983        } else {
3984            text_anchor
3985        }
3986    }
3987
3988    fn contains(&self, anchor: &Anchor) -> bool {
3989        Some(self.buffer_id) == anchor.buffer_id
3990            && self
3991                .range
3992                .context
3993                .start
3994                .cmp(&anchor.text_anchor, &self.buffer)
3995                .is_le()
3996            && self
3997                .range
3998                .context
3999                .end
4000                .cmp(&anchor.text_anchor, &self.buffer)
4001                .is_ge()
4002    }
4003
4004    /// The [`Excerpt`]'s start offset in its [`Buffer`]
4005    fn buffer_start_offset(&self) -> usize {
4006        self.range.context.start.to_offset(&self.buffer)
4007    }
4008
4009    /// The [`Excerpt`]'s end offset in its [`Buffer`]
4010    fn buffer_end_offset(&self) -> usize {
4011        self.buffer_start_offset() + self.text_summary.len
4012    }
4013}
4014
4015impl<'a> MultiBufferExcerpt<'a> {
4016    fn new(excerpt: &'a Excerpt, excerpt_offset: usize) -> Self {
4017        MultiBufferExcerpt {
4018            excerpt,
4019            excerpt_offset,
4020        }
4021    }
4022
4023    pub fn buffer(&self) -> &'a BufferSnapshot {
4024        &self.excerpt.buffer
4025    }
4026
4027    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
4028    pub fn map_offset_to_buffer(&self, offset: usize) -> usize {
4029        self.excerpt.buffer_start_offset() + offset.saturating_sub(self.excerpt_offset)
4030    }
4031
4032    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
4033    pub fn map_range_to_buffer(&self, range: Range<usize>) -> Range<usize> {
4034        self.map_offset_to_buffer(range.start)..self.map_offset_to_buffer(range.end)
4035    }
4036
4037    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
4038    pub fn map_offset_from_buffer(&self, buffer_offset: usize) -> usize {
4039        let mut buffer_offset_in_excerpt =
4040            buffer_offset.saturating_sub(self.excerpt.buffer_start_offset());
4041        buffer_offset_in_excerpt =
4042            cmp::min(buffer_offset_in_excerpt, self.excerpt.text_summary.len);
4043
4044        self.excerpt_offset + buffer_offset_in_excerpt
4045    }
4046
4047    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
4048    pub fn map_range_from_buffer(&self, buffer_range: Range<usize>) -> Range<usize> {
4049        self.map_offset_from_buffer(buffer_range.start)
4050            ..self.map_offset_from_buffer(buffer_range.end)
4051    }
4052
4053    /// Returns true if the entirety of the given range is in the buffer's excerpt
4054    pub fn contains_buffer_range(&self, range: Range<usize>) -> bool {
4055        range.start >= self.excerpt.buffer_start_offset()
4056            && range.end <= self.excerpt.buffer_end_offset()
4057    }
4058}
4059
4060impl ExcerptId {
4061    pub fn min() -> Self {
4062        Self(0)
4063    }
4064
4065    pub fn max() -> Self {
4066        Self(usize::MAX)
4067    }
4068
4069    pub fn to_proto(&self) -> u64 {
4070        self.0 as _
4071    }
4072
4073    pub fn from_proto(proto: u64) -> Self {
4074        Self(proto as _)
4075    }
4076
4077    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
4078        let a = snapshot.excerpt_locator_for_id(*self);
4079        let b = snapshot.excerpt_locator_for_id(*other);
4080        a.cmp(b).then_with(|| self.0.cmp(&other.0))
4081    }
4082}
4083
4084impl Into<usize> for ExcerptId {
4085    fn into(self) -> usize {
4086        self.0
4087    }
4088}
4089
4090impl fmt::Debug for Excerpt {
4091    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4092        f.debug_struct("Excerpt")
4093            .field("id", &self.id)
4094            .field("locator", &self.locator)
4095            .field("buffer_id", &self.buffer_id)
4096            .field("range", &self.range)
4097            .field("text_summary", &self.text_summary)
4098            .field("has_trailing_newline", &self.has_trailing_newline)
4099            .finish()
4100    }
4101}
4102
4103impl sum_tree::Item for Excerpt {
4104    type Summary = ExcerptSummary;
4105
4106    fn summary(&self) -> Self::Summary {
4107        let mut text = self.text_summary.clone();
4108        if self.has_trailing_newline {
4109            text += TextSummary::from("\n");
4110        }
4111        ExcerptSummary {
4112            excerpt_id: self.id,
4113            excerpt_locator: self.locator.clone(),
4114            max_buffer_row: MultiBufferRow(self.max_buffer_row),
4115            text,
4116        }
4117    }
4118}
4119
4120impl sum_tree::Item for ExcerptIdMapping {
4121    type Summary = ExcerptId;
4122
4123    fn summary(&self) -> Self::Summary {
4124        self.id
4125    }
4126}
4127
4128impl sum_tree::KeyedItem for ExcerptIdMapping {
4129    type Key = ExcerptId;
4130
4131    fn key(&self) -> Self::Key {
4132        self.id
4133    }
4134}
4135
4136impl sum_tree::Summary for ExcerptId {
4137    type Context = ();
4138
4139    fn add_summary(&mut self, other: &Self, _: &()) {
4140        *self = *other;
4141    }
4142}
4143
4144impl sum_tree::Summary for ExcerptSummary {
4145    type Context = ();
4146
4147    fn add_summary(&mut self, summary: &Self, _: &()) {
4148        debug_assert!(summary.excerpt_locator > self.excerpt_locator);
4149        self.excerpt_locator = summary.excerpt_locator.clone();
4150        self.text.add_summary(&summary.text, &());
4151        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
4152    }
4153}
4154
4155impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
4156    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4157        *self += &summary.text;
4158    }
4159}
4160
4161impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
4162    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4163        *self += summary.text.len;
4164    }
4165}
4166
4167impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
4168    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4169        Ord::cmp(self, &cursor_location.text.len)
4170    }
4171}
4172
4173impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
4174    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: &()) -> cmp::Ordering {
4175        Ord::cmp(&Some(self), cursor_location)
4176    }
4177}
4178
4179impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Locator {
4180    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
4181        Ord::cmp(self, &cursor_location.excerpt_locator)
4182    }
4183}
4184
4185impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for OffsetUtf16 {
4186    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4187        *self += summary.text.len_utf16;
4188    }
4189}
4190
4191impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
4192    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4193        *self += summary.text.lines;
4194    }
4195}
4196
4197impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
4198    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4199        *self += summary.text.lines_utf16()
4200    }
4201}
4202
4203impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
4204    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4205        *self = Some(&summary.excerpt_locator);
4206    }
4207}
4208
4209impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
4210    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
4211        *self = Some(summary.excerpt_id);
4212    }
4213}
4214
4215impl<'a> MultiBufferRows<'a> {
4216    pub fn seek(&mut self, row: MultiBufferRow) {
4217        self.buffer_row_range = 0..0;
4218
4219        self.excerpts
4220            .seek_forward(&Point::new(row.0, 0), Bias::Right, &());
4221        if self.excerpts.item().is_none() {
4222            self.excerpts.prev(&());
4223
4224            if self.excerpts.item().is_none() && row.0 == 0 {
4225                self.buffer_row_range = 0..1;
4226                return;
4227            }
4228        }
4229
4230        if let Some(excerpt) = self.excerpts.item() {
4231            let overshoot = row.0 - self.excerpts.start().row;
4232            let excerpt_start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4233            self.buffer_row_range.start = excerpt_start + overshoot;
4234            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
4235        }
4236    }
4237}
4238
4239impl<'a> Iterator for MultiBufferRows<'a> {
4240    type Item = Option<u32>;
4241
4242    fn next(&mut self) -> Option<Self::Item> {
4243        loop {
4244            if !self.buffer_row_range.is_empty() {
4245                let row = Some(self.buffer_row_range.start);
4246                self.buffer_row_range.start += 1;
4247                return Some(row);
4248            }
4249            self.excerpts.item()?;
4250            self.excerpts.next(&());
4251            let excerpt = self.excerpts.item()?;
4252            self.buffer_row_range.start = excerpt.range.context.start.to_point(&excerpt.buffer).row;
4253            self.buffer_row_range.end =
4254                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
4255        }
4256    }
4257}
4258
4259impl<'a> MultiBufferChunks<'a> {
4260    pub fn offset(&self) -> usize {
4261        self.range.start
4262    }
4263
4264    pub fn seek(&mut self, offset: usize) {
4265        self.range.start = offset;
4266        self.excerpts.seek(&offset, Bias::Right, &());
4267        if let Some(excerpt) = self.excerpts.item() {
4268            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4269                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
4270                self.language_aware,
4271            ));
4272        } else {
4273            self.excerpt_chunks = None;
4274        }
4275    }
4276}
4277
4278impl<'a> Iterator for MultiBufferChunks<'a> {
4279    type Item = Chunk<'a>;
4280
4281    fn next(&mut self) -> Option<Self::Item> {
4282        if self.range.is_empty() {
4283            None
4284        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
4285            self.range.start += chunk.text.len();
4286            Some(chunk)
4287        } else {
4288            self.excerpts.next(&());
4289            let excerpt = self.excerpts.item()?;
4290            self.excerpt_chunks = Some(excerpt.chunks_in_range(
4291                0..self.range.end - self.excerpts.start(),
4292                self.language_aware,
4293            ));
4294            self.next()
4295        }
4296    }
4297}
4298
4299impl<'a> MultiBufferBytes<'a> {
4300    fn consume(&mut self, len: usize) {
4301        self.range.start += len;
4302        self.chunk = &self.chunk[len..];
4303
4304        if !self.range.is_empty() && self.chunk.is_empty() {
4305            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4306                self.chunk = chunk;
4307            } else {
4308                self.excerpts.next(&());
4309                if let Some(excerpt) = self.excerpts.item() {
4310                    let mut excerpt_bytes =
4311                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
4312                    self.chunk = excerpt_bytes.next().unwrap();
4313                    self.excerpt_bytes = Some(excerpt_bytes);
4314                }
4315            }
4316        }
4317    }
4318}
4319
4320impl<'a> Iterator for MultiBufferBytes<'a> {
4321    type Item = &'a [u8];
4322
4323    fn next(&mut self) -> Option<Self::Item> {
4324        let chunk = self.chunk;
4325        if chunk.is_empty() {
4326            None
4327        } else {
4328            self.consume(chunk.len());
4329            Some(chunk)
4330        }
4331    }
4332}
4333
4334impl<'a> io::Read for MultiBufferBytes<'a> {
4335    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4336        let len = cmp::min(buf.len(), self.chunk.len());
4337        buf[..len].copy_from_slice(&self.chunk[..len]);
4338        if len > 0 {
4339            self.consume(len);
4340        }
4341        Ok(len)
4342    }
4343}
4344
4345impl<'a> ReversedMultiBufferBytes<'a> {
4346    fn consume(&mut self, len: usize) {
4347        self.range.end -= len;
4348        self.chunk = &self.chunk[..self.chunk.len() - len];
4349
4350        if !self.range.is_empty() && self.chunk.is_empty() {
4351            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
4352                self.chunk = chunk;
4353            } else {
4354                self.excerpts.prev(&());
4355                if let Some(excerpt) = self.excerpts.item() {
4356                    let mut excerpt_bytes = excerpt.reversed_bytes_in_range(
4357                        self.range.start.saturating_sub(*self.excerpts.start())..usize::MAX,
4358                    );
4359                    self.chunk = excerpt_bytes.next().unwrap();
4360                    self.excerpt_bytes = Some(excerpt_bytes);
4361                }
4362            }
4363        } else {
4364        }
4365    }
4366}
4367
4368impl<'a> io::Read for ReversedMultiBufferBytes<'a> {
4369    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
4370        let len = cmp::min(buf.len(), self.chunk.len());
4371        buf[..len].copy_from_slice(&self.chunk[..len]);
4372        buf[..len].reverse();
4373        if len > 0 {
4374            self.consume(len);
4375        }
4376        Ok(len)
4377    }
4378}
4379impl<'a> Iterator for ExcerptBytes<'a> {
4380    type Item = &'a [u8];
4381
4382    fn next(&mut self) -> Option<Self::Item> {
4383        if self.reversed && self.padding_height > 0 {
4384            let result = &NEWLINES[..self.padding_height];
4385            self.padding_height = 0;
4386            return Some(result);
4387        }
4388
4389        if let Some(chunk) = self.content_bytes.next() {
4390            if !chunk.is_empty() {
4391                return Some(chunk);
4392            }
4393        }
4394
4395        if self.padding_height > 0 {
4396            let result = &NEWLINES[..self.padding_height];
4397            self.padding_height = 0;
4398            return Some(result);
4399        }
4400
4401        None
4402    }
4403}
4404
4405impl<'a> Iterator for ExcerptChunks<'a> {
4406    type Item = Chunk<'a>;
4407
4408    fn next(&mut self) -> Option<Self::Item> {
4409        if let Some(chunk) = self.content_chunks.next() {
4410            return Some(chunk);
4411        }
4412
4413        if self.footer_height > 0 {
4414            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
4415            self.footer_height = 0;
4416            return Some(Chunk {
4417                text,
4418                ..Default::default()
4419            });
4420        }
4421
4422        None
4423    }
4424}
4425
4426impl ToOffset for Point {
4427    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4428        snapshot.point_to_offset(*self)
4429    }
4430}
4431
4432impl ToOffset for usize {
4433    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4434        assert!(*self <= snapshot.len(), "offset is out of range");
4435        *self
4436    }
4437}
4438
4439impl ToOffset for OffsetUtf16 {
4440    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4441        snapshot.offset_utf16_to_offset(*self)
4442    }
4443}
4444
4445impl ToOffset for PointUtf16 {
4446    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
4447        snapshot.point_utf16_to_offset(*self)
4448    }
4449}
4450
4451impl ToOffsetUtf16 for OffsetUtf16 {
4452    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4453        *self
4454    }
4455}
4456
4457impl ToOffsetUtf16 for usize {
4458    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> OffsetUtf16 {
4459        snapshot.offset_to_offset_utf16(*self)
4460    }
4461}
4462
4463impl ToPoint for usize {
4464    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
4465        snapshot.offset_to_point(*self)
4466    }
4467}
4468
4469impl ToPoint for Point {
4470    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
4471        *self
4472    }
4473}
4474
4475impl ToPointUtf16 for usize {
4476    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4477        snapshot.offset_to_point_utf16(*self)
4478    }
4479}
4480
4481impl ToPointUtf16 for Point {
4482    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
4483        snapshot.point_to_point_utf16(*self)
4484    }
4485}
4486
4487impl ToPointUtf16 for PointUtf16 {
4488    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
4489        *self
4490    }
4491}
4492
4493fn build_excerpt_ranges<T>(
4494    buffer: &BufferSnapshot,
4495    ranges: &[Range<T>],
4496    context_line_count: u32,
4497) -> (Vec<ExcerptRange<Point>>, Vec<usize>)
4498where
4499    T: text::ToPoint,
4500{
4501    let max_point = buffer.max_point();
4502    let mut range_counts = Vec::new();
4503    let mut excerpt_ranges = Vec::new();
4504    let mut range_iter = ranges
4505        .iter()
4506        .map(|range| range.start.to_point(buffer)..range.end.to_point(buffer))
4507        .peekable();
4508    while let Some(range) = range_iter.next() {
4509        let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
4510        // These + 1s ensure that we select the whole next line
4511        let mut excerpt_end = Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
4512
4513        let mut ranges_in_excerpt = 1;
4514
4515        while let Some(next_range) = range_iter.peek() {
4516            if next_range.start.row <= excerpt_end.row + context_line_count {
4517                excerpt_end =
4518                    Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
4519                ranges_in_excerpt += 1;
4520                range_iter.next();
4521            } else {
4522                break;
4523            }
4524        }
4525
4526        excerpt_ranges.push(ExcerptRange {
4527            context: excerpt_start..excerpt_end,
4528            primary: Some(range),
4529        });
4530        range_counts.push(ranges_in_excerpt);
4531    }
4532
4533    (excerpt_ranges, range_counts)
4534}
4535
4536#[cfg(test)]
4537mod tests {
4538    use super::*;
4539    use futures::StreamExt;
4540    use gpui::{AppContext, Context, TestAppContext};
4541    use language::{Buffer, Rope};
4542    use parking_lot::RwLock;
4543    use rand::prelude::*;
4544    use settings::SettingsStore;
4545    use std::env;
4546    use util::test::sample_text;
4547
4548    #[ctor::ctor]
4549    fn init_logger() {
4550        if std::env::var("RUST_LOG").is_ok() {
4551            env_logger::init();
4552        }
4553    }
4554
4555    #[gpui::test]
4556    fn test_singleton(cx: &mut AppContext) {
4557        let buffer = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
4558        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
4559
4560        let snapshot = multibuffer.read(cx).snapshot(cx);
4561        assert_eq!(snapshot.text(), buffer.read(cx).text());
4562
4563        assert_eq!(
4564            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
4565            (0..buffer.read(cx).row_count())
4566                .map(Some)
4567                .collect::<Vec<_>>()
4568        );
4569
4570        buffer.update(cx, |buffer, cx| buffer.edit([(1..3, "XXX\n")], None, cx));
4571        let snapshot = multibuffer.read(cx).snapshot(cx);
4572
4573        assert_eq!(snapshot.text(), buffer.read(cx).text());
4574        assert_eq!(
4575            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
4576            (0..buffer.read(cx).row_count())
4577                .map(Some)
4578                .collect::<Vec<_>>()
4579        );
4580    }
4581
4582    #[gpui::test]
4583    fn test_remote(cx: &mut AppContext) {
4584        let host_buffer = cx.new_model(|cx| Buffer::local("a", cx));
4585        let guest_buffer = cx.new_model(|cx| {
4586            let state = host_buffer.read(cx).to_proto();
4587            let ops = cx
4588                .background_executor()
4589                .block(host_buffer.read(cx).serialize_ops(None, cx));
4590            let mut buffer = Buffer::from_proto(1, Capability::ReadWrite, state, None).unwrap();
4591            buffer
4592                .apply_ops(
4593                    ops.into_iter()
4594                        .map(|op| language::proto::deserialize_operation(op).unwrap()),
4595                    cx,
4596                )
4597                .unwrap();
4598            buffer
4599        });
4600        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
4601        let snapshot = multibuffer.read(cx).snapshot(cx);
4602        assert_eq!(snapshot.text(), "a");
4603
4604        guest_buffer.update(cx, |buffer, cx| buffer.edit([(1..1, "b")], None, cx));
4605        let snapshot = multibuffer.read(cx).snapshot(cx);
4606        assert_eq!(snapshot.text(), "ab");
4607
4608        guest_buffer.update(cx, |buffer, cx| buffer.edit([(2..2, "c")], None, cx));
4609        let snapshot = multibuffer.read(cx).snapshot(cx);
4610        assert_eq!(snapshot.text(), "abc");
4611    }
4612
4613    #[gpui::test]
4614    fn test_excerpt_boundaries_and_clipping(cx: &mut AppContext) {
4615        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'a'), cx));
4616        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(6, 6, 'g'), cx));
4617        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4618
4619        let events = Arc::new(RwLock::new(Vec::<Event>::new()));
4620        multibuffer.update(cx, |_, cx| {
4621            let events = events.clone();
4622            cx.subscribe(&multibuffer, move |_, _, event, _| {
4623                if let Event::Edited { .. } = event {
4624                    events.write().push(event.clone())
4625                }
4626            })
4627            .detach();
4628        });
4629
4630        let subscription = multibuffer.update(cx, |multibuffer, cx| {
4631            let subscription = multibuffer.subscribe();
4632            multibuffer.push_excerpts(
4633                buffer_1.clone(),
4634                [ExcerptRange {
4635                    context: Point::new(1, 2)..Point::new(2, 5),
4636                    primary: None,
4637                }],
4638                cx,
4639            );
4640            assert_eq!(
4641                subscription.consume().into_inner(),
4642                [Edit {
4643                    old: 0..0,
4644                    new: 0..10
4645                }]
4646            );
4647
4648            multibuffer.push_excerpts(
4649                buffer_1.clone(),
4650                [ExcerptRange {
4651                    context: Point::new(3, 3)..Point::new(4, 4),
4652                    primary: None,
4653                }],
4654                cx,
4655            );
4656            multibuffer.push_excerpts(
4657                buffer_2.clone(),
4658                [ExcerptRange {
4659                    context: Point::new(3, 1)..Point::new(3, 3),
4660                    primary: None,
4661                }],
4662                cx,
4663            );
4664            assert_eq!(
4665                subscription.consume().into_inner(),
4666                [Edit {
4667                    old: 10..10,
4668                    new: 10..22
4669                }]
4670            );
4671
4672            subscription
4673        });
4674
4675        // Adding excerpts emits an edited event.
4676        assert_eq!(
4677            events.read().as_slice(),
4678            &[
4679                Event::Edited {
4680                    singleton_buffer_edited: false
4681                },
4682                Event::Edited {
4683                    singleton_buffer_edited: false
4684                },
4685                Event::Edited {
4686                    singleton_buffer_edited: false
4687                }
4688            ]
4689        );
4690
4691        let snapshot = multibuffer.read(cx).snapshot(cx);
4692        assert_eq!(
4693            snapshot.text(),
4694            concat!(
4695                "bbbb\n",  // Preserve newlines
4696                "ccccc\n", //
4697                "ddd\n",   //
4698                "eeee\n",  //
4699                "jj"       //
4700            )
4701        );
4702        assert_eq!(
4703            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
4704            [Some(1), Some(2), Some(3), Some(4), Some(3)]
4705        );
4706        assert_eq!(
4707            snapshot.buffer_rows(MultiBufferRow(2)).collect::<Vec<_>>(),
4708            [Some(3), Some(4), Some(3)]
4709        );
4710        assert_eq!(
4711            snapshot.buffer_rows(MultiBufferRow(4)).collect::<Vec<_>>(),
4712            [Some(3)]
4713        );
4714        assert_eq!(
4715            snapshot.buffer_rows(MultiBufferRow(5)).collect::<Vec<_>>(),
4716            []
4717        );
4718
4719        assert_eq!(
4720            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
4721            &[
4722                (MultiBufferRow(0), "bbbb\nccccc".to_string(), true),
4723                (MultiBufferRow(2), "ddd\neeee".to_string(), false),
4724                (MultiBufferRow(4), "jj".to_string(), true),
4725            ]
4726        );
4727        assert_eq!(
4728            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
4729            &[(MultiBufferRow(0), "bbbb\nccccc".to_string(), true)]
4730        );
4731        assert_eq!(
4732            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
4733            &[]
4734        );
4735        assert_eq!(
4736            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
4737            &[]
4738        );
4739        assert_eq!(
4740            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4741            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
4742        );
4743        assert_eq!(
4744            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
4745            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
4746        );
4747        assert_eq!(
4748            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
4749            &[(MultiBufferRow(2), "ddd\neeee".to_string(), false)]
4750        );
4751        assert_eq!(
4752            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
4753            &[(MultiBufferRow(4), "jj".to_string(), true)]
4754        );
4755        assert_eq!(
4756            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
4757            &[]
4758        );
4759
4760        buffer_1.update(cx, |buffer, cx| {
4761            let text = "\n";
4762            buffer.edit(
4763                [
4764                    (Point::new(0, 0)..Point::new(0, 0), text),
4765                    (Point::new(2, 1)..Point::new(2, 3), text),
4766                ],
4767                None,
4768                cx,
4769            );
4770        });
4771
4772        let snapshot = multibuffer.read(cx).snapshot(cx);
4773        assert_eq!(
4774            snapshot.text(),
4775            concat!(
4776                "bbbb\n", // Preserve newlines
4777                "c\n",    //
4778                "cc\n",   //
4779                "ddd\n",  //
4780                "eeee\n", //
4781                "jj"      //
4782            )
4783        );
4784
4785        assert_eq!(
4786            subscription.consume().into_inner(),
4787            [Edit {
4788                old: 6..8,
4789                new: 6..7
4790            }]
4791        );
4792
4793        let snapshot = multibuffer.read(cx).snapshot(cx);
4794        assert_eq!(
4795            snapshot.clip_point(Point::new(0, 5), Bias::Left),
4796            Point::new(0, 4)
4797        );
4798        assert_eq!(
4799            snapshot.clip_point(Point::new(0, 5), Bias::Right),
4800            Point::new(0, 4)
4801        );
4802        assert_eq!(
4803            snapshot.clip_point(Point::new(5, 1), Bias::Right),
4804            Point::new(5, 1)
4805        );
4806        assert_eq!(
4807            snapshot.clip_point(Point::new(5, 2), Bias::Right),
4808            Point::new(5, 2)
4809        );
4810        assert_eq!(
4811            snapshot.clip_point(Point::new(5, 3), Bias::Right),
4812            Point::new(5, 2)
4813        );
4814
4815        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
4816            let (buffer_2_excerpt_id, _) =
4817                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
4818            multibuffer.remove_excerpts([buffer_2_excerpt_id], cx);
4819            multibuffer.snapshot(cx)
4820        });
4821
4822        assert_eq!(
4823            snapshot.text(),
4824            concat!(
4825                "bbbb\n", // Preserve newlines
4826                "c\n",    //
4827                "cc\n",   //
4828                "ddd\n",  //
4829                "eeee",   //
4830            )
4831        );
4832
4833        fn boundaries_in_range(
4834            range: Range<Point>,
4835            snapshot: &MultiBufferSnapshot,
4836        ) -> Vec<(MultiBufferRow, String, bool)> {
4837            snapshot
4838                .excerpt_boundaries_in_range(range)
4839                .map(|boundary| {
4840                    (
4841                        boundary.row,
4842                        boundary
4843                            .buffer
4844                            .text_for_range(boundary.range.context)
4845                            .collect::<String>(),
4846                        boundary.starts_new_buffer,
4847                    )
4848                })
4849                .collect::<Vec<_>>()
4850        }
4851    }
4852
4853    #[gpui::test]
4854    fn test_excerpt_events(cx: &mut AppContext) {
4855        let buffer_1 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'a'), cx));
4856        let buffer_2 = cx.new_model(|cx| Buffer::local(sample_text(10, 3, 'm'), cx));
4857
4858        let leader_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4859        let follower_multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4860        let follower_edit_event_count = Arc::new(RwLock::new(0));
4861
4862        follower_multibuffer.update(cx, |_, cx| {
4863            let follower_edit_event_count = follower_edit_event_count.clone();
4864            cx.subscribe(
4865                &leader_multibuffer,
4866                move |follower, _, event, cx| match event.clone() {
4867                    Event::ExcerptsAdded {
4868                        buffer,
4869                        predecessor,
4870                        excerpts,
4871                    } => follower.insert_excerpts_with_ids_after(predecessor, buffer, excerpts, cx),
4872                    Event::ExcerptsRemoved { ids } => follower.remove_excerpts(ids, cx),
4873                    Event::Edited { .. } => {
4874                        *follower_edit_event_count.write() += 1;
4875                    }
4876                    _ => {}
4877                },
4878            )
4879            .detach();
4880        });
4881
4882        leader_multibuffer.update(cx, |leader, cx| {
4883            leader.push_excerpts(
4884                buffer_1.clone(),
4885                [
4886                    ExcerptRange {
4887                        context: 0..8,
4888                        primary: None,
4889                    },
4890                    ExcerptRange {
4891                        context: 12..16,
4892                        primary: None,
4893                    },
4894                ],
4895                cx,
4896            );
4897            leader.insert_excerpts_after(
4898                leader.excerpt_ids()[0],
4899                buffer_2.clone(),
4900                [
4901                    ExcerptRange {
4902                        context: 0..5,
4903                        primary: None,
4904                    },
4905                    ExcerptRange {
4906                        context: 10..15,
4907                        primary: None,
4908                    },
4909                ],
4910                cx,
4911            )
4912        });
4913        assert_eq!(
4914            leader_multibuffer.read(cx).snapshot(cx).text(),
4915            follower_multibuffer.read(cx).snapshot(cx).text(),
4916        );
4917        assert_eq!(*follower_edit_event_count.read(), 2);
4918
4919        leader_multibuffer.update(cx, |leader, cx| {
4920            let excerpt_ids = leader.excerpt_ids();
4921            leader.remove_excerpts([excerpt_ids[1], excerpt_ids[3]], cx);
4922        });
4923        assert_eq!(
4924            leader_multibuffer.read(cx).snapshot(cx).text(),
4925            follower_multibuffer.read(cx).snapshot(cx).text(),
4926        );
4927        assert_eq!(*follower_edit_event_count.read(), 3);
4928
4929        // Removing an empty set of excerpts is a noop.
4930        leader_multibuffer.update(cx, |leader, cx| {
4931            leader.remove_excerpts([], cx);
4932        });
4933        assert_eq!(
4934            leader_multibuffer.read(cx).snapshot(cx).text(),
4935            follower_multibuffer.read(cx).snapshot(cx).text(),
4936        );
4937        assert_eq!(*follower_edit_event_count.read(), 3);
4938
4939        // Adding an empty set of excerpts is a noop.
4940        leader_multibuffer.update(cx, |leader, cx| {
4941            leader.push_excerpts::<usize>(buffer_2.clone(), [], cx);
4942        });
4943        assert_eq!(
4944            leader_multibuffer.read(cx).snapshot(cx).text(),
4945            follower_multibuffer.read(cx).snapshot(cx).text(),
4946        );
4947        assert_eq!(*follower_edit_event_count.read(), 3);
4948
4949        leader_multibuffer.update(cx, |leader, cx| {
4950            leader.clear(cx);
4951        });
4952        assert_eq!(
4953            leader_multibuffer.read(cx).snapshot(cx).text(),
4954            follower_multibuffer.read(cx).snapshot(cx).text(),
4955        );
4956        assert_eq!(*follower_edit_event_count.read(), 4);
4957    }
4958
4959    #[gpui::test]
4960    fn test_expand_excerpts(cx: &mut AppContext) {
4961        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
4962        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
4963
4964        multibuffer.update(cx, |multibuffer, cx| {
4965            multibuffer.push_excerpts_with_context_lines(
4966                buffer.clone(),
4967                vec![
4968                    // Note that in this test, this first excerpt
4969                    // does not contain a new line
4970                    Point::new(3, 2)..Point::new(3, 3),
4971                    Point::new(7, 1)..Point::new(7, 3),
4972                    Point::new(15, 0)..Point::new(15, 0),
4973                ],
4974                1,
4975                cx,
4976            )
4977        });
4978
4979        multibuffer.update(cx, |multibuffer, cx| {
4980            multibuffer.expand_excerpts(multibuffer.excerpt_ids(), 1, cx)
4981        });
4982
4983        let snapshot = multibuffer.read(cx).snapshot(cx);
4984
4985        // Expanding context lines causes the line containing 'fff' to appear in two different excerpts.
4986        // We don't attempt to merge them, because removing the excerpt could create inconsistency with other layers
4987        // that are tracking excerpt ids.
4988        assert_eq!(
4989            snapshot.text(),
4990            concat!(
4991                "bbb\n", // Preserve newlines
4992                "ccc\n", //
4993                "ddd\n", //
4994                "eee\n", //
4995                "fff\n", // <- Same as below
4996                "\n",    // Excerpt boundary
4997                "fff\n", // <- Same as above
4998                "ggg\n", //
4999                "hhh\n", //
5000                "iii\n", //
5001                "jjj\n", //
5002                "\n",    //
5003                "nnn\n", //
5004                "ooo\n", //
5005                "ppp\n", //
5006                "qqq\n", //
5007                "rrr\n", //
5008            )
5009        );
5010    }
5011
5012    #[gpui::test]
5013    fn test_push_excerpts_with_context_lines(cx: &mut AppContext) {
5014        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5015        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5016        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
5017            multibuffer.push_excerpts_with_context_lines(
5018                buffer.clone(),
5019                vec![
5020                    // Note that in this test, this first excerpt
5021                    // does contain a new line
5022                    Point::new(3, 2)..Point::new(4, 2),
5023                    Point::new(7, 1)..Point::new(7, 3),
5024                    Point::new(15, 0)..Point::new(15, 0),
5025                ],
5026                2,
5027                cx,
5028            )
5029        });
5030
5031        let snapshot = multibuffer.read(cx).snapshot(cx);
5032        assert_eq!(
5033            snapshot.text(),
5034            concat!(
5035                "bbb\n", // Preserve newlines
5036                "ccc\n", //
5037                "ddd\n", //
5038                "eee\n", //
5039                "fff\n", //
5040                "ggg\n", //
5041                "hhh\n", //
5042                "iii\n", //
5043                "jjj\n", //
5044                "\n",    //
5045                "nnn\n", //
5046                "ooo\n", //
5047                "ppp\n", //
5048                "qqq\n", //
5049                "rrr\n", //
5050            )
5051        );
5052
5053        assert_eq!(
5054            anchor_ranges
5055                .iter()
5056                .map(|range| range.to_point(&snapshot))
5057                .collect::<Vec<_>>(),
5058            vec![
5059                Point::new(2, 2)..Point::new(3, 2),
5060                Point::new(6, 1)..Point::new(6, 3),
5061                Point::new(12, 0)..Point::new(12, 0)
5062            ]
5063        );
5064    }
5065
5066    #[gpui::test]
5067    async fn test_stream_excerpts_with_context_lines(cx: &mut TestAppContext) {
5068        let buffer = cx.new_model(|cx| Buffer::local(sample_text(20, 3, 'a'), cx));
5069        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5070        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
5071            let snapshot = buffer.read(cx);
5072            let ranges = vec![
5073                snapshot.anchor_before(Point::new(3, 2))..snapshot.anchor_before(Point::new(4, 2)),
5074                snapshot.anchor_before(Point::new(7, 1))..snapshot.anchor_before(Point::new(7, 3)),
5075                snapshot.anchor_before(Point::new(15, 0))
5076                    ..snapshot.anchor_before(Point::new(15, 0)),
5077            ];
5078            multibuffer.stream_excerpts_with_context_lines(buffer.clone(), ranges, 2, cx)
5079        });
5080
5081        let anchor_ranges = anchor_ranges.collect::<Vec<_>>().await;
5082
5083        let snapshot = multibuffer.update(cx, |multibuffer, cx| multibuffer.snapshot(cx));
5084        assert_eq!(
5085            snapshot.text(),
5086            concat!(
5087                "bbb\n", //
5088                "ccc\n", //
5089                "ddd\n", //
5090                "eee\n", //
5091                "fff\n", //
5092                "ggg\n", //
5093                "hhh\n", //
5094                "iii\n", //
5095                "jjj\n", //
5096                "\n",    //
5097                "nnn\n", //
5098                "ooo\n", //
5099                "ppp\n", //
5100                "qqq\n", //
5101                "rrr\n", //
5102            )
5103        );
5104
5105        assert_eq!(
5106            anchor_ranges
5107                .iter()
5108                .map(|range| range.to_point(&snapshot))
5109                .collect::<Vec<_>>(),
5110            vec![
5111                Point::new(2, 2)..Point::new(3, 2),
5112                Point::new(6, 1)..Point::new(6, 3),
5113                Point::new(12, 0)..Point::new(12, 0)
5114            ]
5115        );
5116    }
5117
5118    #[gpui::test]
5119    fn test_empty_multibuffer(cx: &mut AppContext) {
5120        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5121
5122        let snapshot = multibuffer.read(cx).snapshot(cx);
5123        assert_eq!(snapshot.text(), "");
5124        assert_eq!(
5125            snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5126            &[Some(0)]
5127        );
5128        assert_eq!(
5129            snapshot.buffer_rows(MultiBufferRow(1)).collect::<Vec<_>>(),
5130            &[]
5131        );
5132    }
5133
5134    #[gpui::test]
5135    fn test_singleton_multibuffer_anchors(cx: &mut AppContext) {
5136        let buffer = cx.new_model(|cx| Buffer::local("abcd", cx));
5137        let multibuffer = cx.new_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
5138        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5139        buffer.update(cx, |buffer, cx| {
5140            buffer.edit([(0..0, "X")], None, cx);
5141            buffer.edit([(5..5, "Y")], None, cx);
5142        });
5143        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5144
5145        assert_eq!(old_snapshot.text(), "abcd");
5146        assert_eq!(new_snapshot.text(), "XabcdY");
5147
5148        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5149        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5150        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
5151        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
5152    }
5153
5154    #[gpui::test]
5155    fn test_multibuffer_anchors(cx: &mut AppContext) {
5156        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5157        let buffer_2 = cx.new_model(|cx| Buffer::local("efghi", cx));
5158        let multibuffer = cx.new_model(|cx| {
5159            let mut multibuffer = MultiBuffer::new(0, Capability::ReadWrite);
5160            multibuffer.push_excerpts(
5161                buffer_1.clone(),
5162                [ExcerptRange {
5163                    context: 0..4,
5164                    primary: None,
5165                }],
5166                cx,
5167            );
5168            multibuffer.push_excerpts(
5169                buffer_2.clone(),
5170                [ExcerptRange {
5171                    context: 0..5,
5172                    primary: None,
5173                }],
5174                cx,
5175            );
5176            multibuffer
5177        });
5178        let old_snapshot = multibuffer.read(cx).snapshot(cx);
5179
5180        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
5181        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
5182        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5183        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
5184        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5185        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
5186
5187        buffer_1.update(cx, |buffer, cx| {
5188            buffer.edit([(0..0, "W")], None, cx);
5189            buffer.edit([(5..5, "X")], None, cx);
5190        });
5191        buffer_2.update(cx, |buffer, cx| {
5192            buffer.edit([(0..0, "Y")], None, cx);
5193            buffer.edit([(6..6, "Z")], None, cx);
5194        });
5195        let new_snapshot = multibuffer.read(cx).snapshot(cx);
5196
5197        assert_eq!(old_snapshot.text(), "abcd\nefghi");
5198        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
5199
5200        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
5201        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
5202        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
5203        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
5204        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
5205        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
5206        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
5207        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
5208        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
5209        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
5210    }
5211
5212    #[gpui::test]
5213    fn test_resolving_anchors_after_replacing_their_excerpts(cx: &mut AppContext) {
5214        let buffer_1 = cx.new_model(|cx| Buffer::local("abcd", cx));
5215        let buffer_2 = cx.new_model(|cx| Buffer::local("ABCDEFGHIJKLMNOP", cx));
5216        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5217
5218        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
5219        // Add an excerpt from buffer 1 that spans this new insertion.
5220        buffer_1.update(cx, |buffer, cx| buffer.edit([(4..4, "123")], None, cx));
5221        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
5222            multibuffer
5223                .push_excerpts(
5224                    buffer_1.clone(),
5225                    [ExcerptRange {
5226                        context: 0..7,
5227                        primary: None,
5228                    }],
5229                    cx,
5230                )
5231                .pop()
5232                .unwrap()
5233        });
5234
5235        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
5236        assert_eq!(snapshot_1.text(), "abcd123");
5237
5238        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
5239        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
5240            multibuffer.remove_excerpts([excerpt_id_1], cx);
5241            let mut ids = multibuffer
5242                .push_excerpts(
5243                    buffer_2.clone(),
5244                    [
5245                        ExcerptRange {
5246                            context: 0..4,
5247                            primary: None,
5248                        },
5249                        ExcerptRange {
5250                            context: 6..10,
5251                            primary: None,
5252                        },
5253                        ExcerptRange {
5254                            context: 12..16,
5255                            primary: None,
5256                        },
5257                    ],
5258                    cx,
5259                )
5260                .into_iter();
5261            (ids.next().unwrap(), ids.next().unwrap())
5262        });
5263        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
5264        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
5265
5266        // The old excerpt id doesn't get reused.
5267        assert_ne!(excerpt_id_2, excerpt_id_1);
5268
5269        // Resolve some anchors from the previous snapshot in the new snapshot.
5270        // The current excerpts are from a different buffer, so we don't attempt to
5271        // resolve the old text anchor in the new buffer.
5272        assert_eq!(
5273            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
5274            0
5275        );
5276        assert_eq!(
5277            snapshot_2.summaries_for_anchors::<usize, _>(&[
5278                snapshot_1.anchor_before(2),
5279                snapshot_1.anchor_after(3)
5280            ]),
5281            vec![0, 0]
5282        );
5283
5284        // Refresh anchors from the old snapshot. The return value indicates that both
5285        // anchors lost their original excerpt.
5286        let refresh =
5287            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
5288        assert_eq!(
5289            refresh,
5290            &[
5291                (0, snapshot_2.anchor_before(0), false),
5292                (1, snapshot_2.anchor_after(0), false),
5293            ]
5294        );
5295
5296        // Replace the middle excerpt with a smaller excerpt in buffer 2,
5297        // that intersects the old excerpt.
5298        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
5299            multibuffer.remove_excerpts([excerpt_id_3], cx);
5300            multibuffer
5301                .insert_excerpts_after(
5302                    excerpt_id_2,
5303                    buffer_2.clone(),
5304                    [ExcerptRange {
5305                        context: 5..8,
5306                        primary: None,
5307                    }],
5308                    cx,
5309                )
5310                .pop()
5311                .unwrap()
5312        });
5313
5314        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
5315        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
5316        assert_ne!(excerpt_id_5, excerpt_id_3);
5317
5318        // Resolve some anchors from the previous snapshot in the new snapshot.
5319        // The third anchor can't be resolved, since its excerpt has been removed,
5320        // so it resolves to the same position as its predecessor.
5321        let anchors = [
5322            snapshot_2.anchor_before(0),
5323            snapshot_2.anchor_after(2),
5324            snapshot_2.anchor_after(6),
5325            snapshot_2.anchor_after(14),
5326        ];
5327        assert_eq!(
5328            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
5329            &[0, 2, 9, 13]
5330        );
5331
5332        let new_anchors = snapshot_3.refresh_anchors(&anchors);
5333        assert_eq!(
5334            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
5335            &[(0, true), (1, true), (2, true), (3, true)]
5336        );
5337        assert_eq!(
5338            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
5339            &[0, 2, 7, 13]
5340        );
5341    }
5342
5343    #[gpui::test(iterations = 100)]
5344    fn test_random_multibuffer(cx: &mut AppContext, mut rng: StdRng) {
5345        let operations = env::var("OPERATIONS")
5346            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
5347            .unwrap_or(10);
5348
5349        let mut buffers: Vec<Model<Buffer>> = Vec::new();
5350        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5351        let mut excerpt_ids = Vec::<ExcerptId>::new();
5352        let mut expected_excerpts = Vec::<(Model<Buffer>, Range<text::Anchor>)>::new();
5353        let mut anchors = Vec::new();
5354        let mut old_versions = Vec::new();
5355
5356        for _ in 0..operations {
5357            match rng.gen_range(0..100) {
5358                0..=14 if !buffers.is_empty() => {
5359                    let buffer = buffers.choose(&mut rng).unwrap();
5360                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
5361                }
5362                15..=19 if !expected_excerpts.is_empty() => {
5363                    multibuffer.update(cx, |multibuffer, cx| {
5364                        let ids = multibuffer.excerpt_ids();
5365                        let mut excerpts = HashSet::default();
5366                        for _ in 0..rng.gen_range(0..ids.len()) {
5367                            excerpts.extend(ids.choose(&mut rng).copied());
5368                        }
5369
5370                        let line_count = rng.gen_range(0..5);
5371
5372                        let excerpt_ixs = excerpts
5373                            .iter()
5374                            .map(|id| excerpt_ids.iter().position(|i| i == id).unwrap())
5375                            .collect::<Vec<_>>();
5376                        log::info!("Expanding excerpts {excerpt_ixs:?} by {line_count} lines");
5377                        multibuffer.expand_excerpts(excerpts.iter().cloned(), line_count, cx);
5378
5379                        if line_count > 0 {
5380                            for id in excerpts {
5381                                let excerpt_ix = excerpt_ids.iter().position(|&i| i == id).unwrap();
5382                                let (buffer, range) = &mut expected_excerpts[excerpt_ix];
5383                                let snapshot = buffer.read(cx).snapshot();
5384                                let mut point_range = range.to_point(&snapshot);
5385                                point_range.start =
5386                                    Point::new(point_range.start.row.saturating_sub(line_count), 0);
5387                                point_range.end = snapshot.clip_point(
5388                                    Point::new(point_range.end.row + line_count, 0),
5389                                    Bias::Left,
5390                                );
5391                                *range = snapshot.anchor_before(point_range.start)
5392                                    ..snapshot.anchor_after(point_range.end);
5393                            }
5394                        }
5395                    });
5396                }
5397                20..=29 if !expected_excerpts.is_empty() => {
5398                    let mut ids_to_remove = vec![];
5399                    for _ in 0..rng.gen_range(1..=3) {
5400                        if expected_excerpts.is_empty() {
5401                            break;
5402                        }
5403
5404                        let ix = rng.gen_range(0..expected_excerpts.len());
5405                        ids_to_remove.push(excerpt_ids.remove(ix));
5406                        let (buffer, range) = expected_excerpts.remove(ix);
5407                        let buffer = buffer.read(cx);
5408                        log::info!(
5409                            "Removing excerpt {}: {:?}",
5410                            ix,
5411                            buffer
5412                                .text_for_range(range.to_offset(buffer))
5413                                .collect::<String>(),
5414                        );
5415                    }
5416                    let snapshot = multibuffer.read(cx).read(cx);
5417                    ids_to_remove.sort_unstable_by(|a, b| a.cmp(&b, &snapshot));
5418                    drop(snapshot);
5419                    multibuffer.update(cx, |multibuffer, cx| {
5420                        multibuffer.remove_excerpts(ids_to_remove, cx)
5421                    });
5422                }
5423                30..=39 if !expected_excerpts.is_empty() => {
5424                    let multibuffer = multibuffer.read(cx).read(cx);
5425                    let offset =
5426                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
5427                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
5428                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
5429                    anchors.push(multibuffer.anchor_at(offset, bias));
5430                    anchors.sort_by(|a, b| a.cmp(b, &multibuffer));
5431                }
5432                40..=44 if !anchors.is_empty() => {
5433                    let multibuffer = multibuffer.read(cx).read(cx);
5434                    let prev_len = anchors.len();
5435                    anchors = multibuffer
5436                        .refresh_anchors(&anchors)
5437                        .into_iter()
5438                        .map(|a| a.1)
5439                        .collect();
5440
5441                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
5442                    // overshoot its boundaries.
5443                    assert_eq!(anchors.len(), prev_len);
5444                    for anchor in &anchors {
5445                        if anchor.excerpt_id == ExcerptId::min()
5446                            || anchor.excerpt_id == ExcerptId::max()
5447                        {
5448                            continue;
5449                        }
5450
5451                        let excerpt = multibuffer.excerpt(anchor.excerpt_id).unwrap();
5452                        assert_eq!(excerpt.id, anchor.excerpt_id);
5453                        assert!(excerpt.contains(anchor));
5454                    }
5455                }
5456                _ => {
5457                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
5458                        let base_text = util::RandomCharIter::new(&mut rng)
5459                            .take(25)
5460                            .collect::<String>();
5461
5462                        buffers.push(cx.new_model(|cx| Buffer::local(base_text, cx)));
5463                        buffers.last().unwrap()
5464                    } else {
5465                        buffers.choose(&mut rng).unwrap()
5466                    };
5467
5468                    let buffer = buffer_handle.read(cx);
5469                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
5470                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5471                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
5472                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
5473                    let prev_excerpt_id = excerpt_ids
5474                        .get(prev_excerpt_ix)
5475                        .cloned()
5476                        .unwrap_or_else(ExcerptId::max);
5477                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
5478
5479                    log::info!(
5480                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
5481                        excerpt_ix,
5482                        expected_excerpts.len(),
5483                        buffer_handle.read(cx).remote_id(),
5484                        buffer.text(),
5485                        start_ix..end_ix,
5486                        &buffer.text()[start_ix..end_ix]
5487                    );
5488
5489                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
5490                        multibuffer
5491                            .insert_excerpts_after(
5492                                prev_excerpt_id,
5493                                buffer_handle.clone(),
5494                                [ExcerptRange {
5495                                    context: start_ix..end_ix,
5496                                    primary: None,
5497                                }],
5498                                cx,
5499                            )
5500                            .pop()
5501                            .unwrap()
5502                    });
5503
5504                    excerpt_ids.insert(excerpt_ix, excerpt_id);
5505                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
5506                }
5507            }
5508
5509            if rng.gen_bool(0.3) {
5510                multibuffer.update(cx, |multibuffer, cx| {
5511                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
5512                })
5513            }
5514
5515            let snapshot = multibuffer.read(cx).snapshot(cx);
5516
5517            let mut excerpt_starts = Vec::new();
5518            let mut expected_text = String::new();
5519            let mut expected_buffer_rows = Vec::new();
5520            for (buffer, range) in &expected_excerpts {
5521                let buffer = buffer.read(cx);
5522                let buffer_range = range.to_offset(buffer);
5523
5524                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
5525                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
5526                expected_text.push('\n');
5527
5528                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
5529                    ..=buffer.offset_to_point(buffer_range.end).row;
5530                for row in buffer_row_range {
5531                    expected_buffer_rows.push(Some(row));
5532                }
5533            }
5534            // Remove final trailing newline.
5535            if !expected_excerpts.is_empty() {
5536                expected_text.pop();
5537            }
5538
5539            // Always report one buffer row
5540            if expected_buffer_rows.is_empty() {
5541                expected_buffer_rows.push(Some(0));
5542            }
5543
5544            assert_eq!(snapshot.text(), expected_text);
5545            log::info!("MultiBuffer text: {:?}", expected_text);
5546
5547            assert_eq!(
5548                snapshot.buffer_rows(MultiBufferRow(0)).collect::<Vec<_>>(),
5549                expected_buffer_rows,
5550            );
5551
5552            for _ in 0..5 {
5553                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
5554                assert_eq!(
5555                    snapshot
5556                        .buffer_rows(MultiBufferRow(start_row as u32))
5557                        .collect::<Vec<_>>(),
5558                    &expected_buffer_rows[start_row..],
5559                    "buffer_rows({})",
5560                    start_row
5561                );
5562            }
5563
5564            assert_eq!(
5565                snapshot.max_buffer_row().0,
5566                expected_buffer_rows.into_iter().flatten().max().unwrap()
5567            );
5568
5569            let mut excerpt_starts = excerpt_starts.into_iter();
5570            for (buffer, range) in &expected_excerpts {
5571                let buffer = buffer.read(cx);
5572                let buffer_id = buffer.remote_id();
5573                let buffer_range = range.to_offset(buffer);
5574                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
5575                let buffer_start_point_utf16 =
5576                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
5577
5578                let excerpt_start = excerpt_starts.next().unwrap();
5579                let mut offset = excerpt_start.len;
5580                let mut buffer_offset = buffer_range.start;
5581                let mut point = excerpt_start.lines;
5582                let mut buffer_point = buffer_start_point;
5583                let mut point_utf16 = excerpt_start.lines_utf16();
5584                let mut buffer_point_utf16 = buffer_start_point_utf16;
5585                for ch in buffer
5586                    .snapshot()
5587                    .chunks(buffer_range.clone(), false)
5588                    .flat_map(|c| c.text.chars())
5589                {
5590                    for _ in 0..ch.len_utf8() {
5591                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
5592                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
5593                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
5594                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
5595                        assert_eq!(
5596                            left_offset,
5597                            excerpt_start.len + (buffer_left_offset - buffer_range.start),
5598                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
5599                            offset,
5600                            buffer_id,
5601                            buffer_offset,
5602                        );
5603                        assert_eq!(
5604                            right_offset,
5605                            excerpt_start.len + (buffer_right_offset - buffer_range.start),
5606                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
5607                            offset,
5608                            buffer_id,
5609                            buffer_offset,
5610                        );
5611
5612                        let left_point = snapshot.clip_point(point, Bias::Left);
5613                        let right_point = snapshot.clip_point(point, Bias::Right);
5614                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
5615                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
5616                        assert_eq!(
5617                            left_point,
5618                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
5619                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
5620                            point,
5621                            buffer_id,
5622                            buffer_point,
5623                        );
5624                        assert_eq!(
5625                            right_point,
5626                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
5627                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
5628                            point,
5629                            buffer_id,
5630                            buffer_point,
5631                        );
5632
5633                        assert_eq!(
5634                            snapshot.point_to_offset(left_point),
5635                            left_offset,
5636                            "point_to_offset({:?})",
5637                            left_point,
5638                        );
5639                        assert_eq!(
5640                            snapshot.offset_to_point(left_offset),
5641                            left_point,
5642                            "offset_to_point({:?})",
5643                            left_offset,
5644                        );
5645
5646                        offset += 1;
5647                        buffer_offset += 1;
5648                        if ch == '\n' {
5649                            point += Point::new(1, 0);
5650                            buffer_point += Point::new(1, 0);
5651                        } else {
5652                            point += Point::new(0, 1);
5653                            buffer_point += Point::new(0, 1);
5654                        }
5655                    }
5656
5657                    for _ in 0..ch.len_utf16() {
5658                        let left_point_utf16 =
5659                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Left);
5660                        let right_point_utf16 =
5661                            snapshot.clip_point_utf16(Unclipped(point_utf16), Bias::Right);
5662                        let buffer_left_point_utf16 =
5663                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Left);
5664                        let buffer_right_point_utf16 =
5665                            buffer.clip_point_utf16(Unclipped(buffer_point_utf16), Bias::Right);
5666                        assert_eq!(
5667                            left_point_utf16,
5668                            excerpt_start.lines_utf16()
5669                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
5670                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
5671                            point_utf16,
5672                            buffer_id,
5673                            buffer_point_utf16,
5674                        );
5675                        assert_eq!(
5676                            right_point_utf16,
5677                            excerpt_start.lines_utf16()
5678                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
5679                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
5680                            point_utf16,
5681                            buffer_id,
5682                            buffer_point_utf16,
5683                        );
5684
5685                        if ch == '\n' {
5686                            point_utf16 += PointUtf16::new(1, 0);
5687                            buffer_point_utf16 += PointUtf16::new(1, 0);
5688                        } else {
5689                            point_utf16 += PointUtf16::new(0, 1);
5690                            buffer_point_utf16 += PointUtf16::new(0, 1);
5691                        }
5692                    }
5693                }
5694            }
5695
5696            for (row, line) in expected_text.split('\n').enumerate() {
5697                assert_eq!(
5698                    snapshot.line_len(MultiBufferRow(row as u32)),
5699                    line.len() as u32,
5700                    "line_len({}).",
5701                    row
5702                );
5703            }
5704
5705            let text_rope = Rope::from(expected_text.as_str());
5706            for _ in 0..10 {
5707                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5708                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
5709
5710                let text_for_range = snapshot
5711                    .text_for_range(start_ix..end_ix)
5712                    .collect::<String>();
5713                assert_eq!(
5714                    text_for_range,
5715                    &expected_text[start_ix..end_ix],
5716                    "incorrect text for range {:?}",
5717                    start_ix..end_ix
5718                );
5719
5720                let excerpted_buffer_ranges = multibuffer
5721                    .read(cx)
5722                    .range_to_buffer_ranges(start_ix..end_ix, cx);
5723                let excerpted_buffers_text = excerpted_buffer_ranges
5724                    .iter()
5725                    .map(|(buffer, buffer_range, _)| {
5726                        buffer
5727                            .read(cx)
5728                            .text_for_range(buffer_range.clone())
5729                            .collect::<String>()
5730                    })
5731                    .collect::<Vec<_>>()
5732                    .join("\n");
5733                assert_eq!(excerpted_buffers_text, text_for_range);
5734                if !expected_excerpts.is_empty() {
5735                    assert!(!excerpted_buffer_ranges.is_empty());
5736                }
5737
5738                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
5739                assert_eq!(
5740                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
5741                    expected_summary,
5742                    "incorrect summary for range {:?}",
5743                    start_ix..end_ix
5744                );
5745            }
5746
5747            // Anchor resolution
5748            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
5749            assert_eq!(anchors.len(), summaries.len());
5750            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
5751                assert!(resolved_offset <= snapshot.len());
5752                assert_eq!(
5753                    snapshot.summary_for_anchor::<usize>(anchor),
5754                    resolved_offset
5755                );
5756            }
5757
5758            for _ in 0..10 {
5759                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
5760                assert_eq!(
5761                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
5762                    expected_text[..end_ix].chars().rev().collect::<String>(),
5763                );
5764            }
5765
5766            for _ in 0..10 {
5767                let end_ix = rng.gen_range(0..=text_rope.len());
5768                let start_ix = rng.gen_range(0..=end_ix);
5769                assert_eq!(
5770                    snapshot
5771                        .bytes_in_range(start_ix..end_ix)
5772                        .flatten()
5773                        .copied()
5774                        .collect::<Vec<_>>(),
5775                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
5776                    "bytes_in_range({:?})",
5777                    start_ix..end_ix,
5778                );
5779            }
5780        }
5781
5782        let snapshot = multibuffer.read(cx).snapshot(cx);
5783        for (old_snapshot, subscription) in old_versions {
5784            let edits = subscription.consume().into_inner();
5785
5786            log::info!(
5787                "applying subscription edits to old text: {:?}: {:?}",
5788                old_snapshot.text(),
5789                edits,
5790            );
5791
5792            let mut text = old_snapshot.text();
5793            for edit in edits {
5794                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
5795                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
5796            }
5797            assert_eq!(text.to_string(), snapshot.text());
5798        }
5799    }
5800
5801    #[gpui::test]
5802    fn test_history(cx: &mut AppContext) {
5803        let test_settings = SettingsStore::test(cx);
5804        cx.set_global(test_settings);
5805
5806        let buffer_1 = cx.new_model(|cx| Buffer::local("1234", cx));
5807        let buffer_2 = cx.new_model(|cx| Buffer::local("5678", cx));
5808        let multibuffer = cx.new_model(|_| MultiBuffer::new(0, Capability::ReadWrite));
5809        let group_interval = multibuffer.read(cx).history.group_interval;
5810        multibuffer.update(cx, |multibuffer, cx| {
5811            multibuffer.push_excerpts(
5812                buffer_1.clone(),
5813                [ExcerptRange {
5814                    context: 0..buffer_1.read(cx).len(),
5815                    primary: None,
5816                }],
5817                cx,
5818            );
5819            multibuffer.push_excerpts(
5820                buffer_2.clone(),
5821                [ExcerptRange {
5822                    context: 0..buffer_2.read(cx).len(),
5823                    primary: None,
5824                }],
5825                cx,
5826            );
5827        });
5828
5829        let mut now = Instant::now();
5830
5831        multibuffer.update(cx, |multibuffer, cx| {
5832            let transaction_1 = multibuffer.start_transaction_at(now, cx).unwrap();
5833            multibuffer.edit(
5834                [
5835                    (Point::new(0, 0)..Point::new(0, 0), "A"),
5836                    (Point::new(1, 0)..Point::new(1, 0), "A"),
5837                ],
5838                None,
5839                cx,
5840            );
5841            multibuffer.edit(
5842                [
5843                    (Point::new(0, 1)..Point::new(0, 1), "B"),
5844                    (Point::new(1, 1)..Point::new(1, 1), "B"),
5845                ],
5846                None,
5847                cx,
5848            );
5849            multibuffer.end_transaction_at(now, cx);
5850            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5851
5852            // Edit buffer 1 through the multibuffer
5853            now += 2 * group_interval;
5854            multibuffer.start_transaction_at(now, cx);
5855            multibuffer.edit([(2..2, "C")], None, cx);
5856            multibuffer.end_transaction_at(now, cx);
5857            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
5858
5859            // Edit buffer 1 independently
5860            buffer_1.update(cx, |buffer_1, cx| {
5861                buffer_1.start_transaction_at(now);
5862                buffer_1.edit([(3..3, "D")], None, cx);
5863                buffer_1.end_transaction_at(now, cx);
5864
5865                now += 2 * group_interval;
5866                buffer_1.start_transaction_at(now);
5867                buffer_1.edit([(4..4, "E")], None, cx);
5868                buffer_1.end_transaction_at(now, cx);
5869            });
5870            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5871
5872            // An undo in the multibuffer undoes the multibuffer transaction
5873            // and also any individual buffer edits that have occurred since
5874            // that transaction.
5875            multibuffer.undo(cx);
5876            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5877
5878            multibuffer.undo(cx);
5879            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5880
5881            multibuffer.redo(cx);
5882            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5883
5884            multibuffer.redo(cx);
5885            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
5886
5887            // Undo buffer 2 independently.
5888            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
5889            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
5890
5891            // An undo in the multibuffer undoes the components of the
5892            // the last multibuffer transaction that are not already undone.
5893            multibuffer.undo(cx);
5894            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
5895
5896            multibuffer.undo(cx);
5897            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5898
5899            multibuffer.redo(cx);
5900            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
5901
5902            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
5903            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5904
5905            // Redo stack gets cleared after an edit.
5906            now += 2 * group_interval;
5907            multibuffer.start_transaction_at(now, cx);
5908            multibuffer.edit([(0..0, "X")], None, cx);
5909            multibuffer.end_transaction_at(now, cx);
5910            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5911            multibuffer.redo(cx);
5912            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5913            multibuffer.undo(cx);
5914            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
5915            multibuffer.undo(cx);
5916            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5917
5918            // Transactions can be grouped manually.
5919            multibuffer.redo(cx);
5920            multibuffer.redo(cx);
5921            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5922            multibuffer.group_until_transaction(transaction_1, cx);
5923            multibuffer.undo(cx);
5924            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
5925            multibuffer.redo(cx);
5926            assert_eq!(multibuffer.read(cx).text(), "XABCD1234\nAB5678");
5927        });
5928    }
5929}