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