multi_buffer.rs

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