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