multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::{Bound, HashMap, HashSet};
   7use gpui::{AppContext, Entity, ModelContext, ModelHandle, Task};
   8pub use language::Completion;
   9use language::{
  10    char_kind, Buffer, BufferChunks, BufferSnapshot, CharKind, Chunk, DiagnosticEntry, Event, File,
  11    Language, OffsetRangeExt, Outline, OutlineItem, Selection, ToOffset as _, ToPoint as _,
  12    ToPointUtf16 as _, TransactionId,
  13};
  14use settings::Settings;
  15use std::{
  16    cell::{Ref, RefCell},
  17    cmp, fmt, io,
  18    iter::{self, FromIterator},
  19    ops::{Range, RangeBounds, Sub},
  20    str,
  21    sync::Arc,
  22    time::{Duration, Instant},
  23};
  24use sum_tree::{Bias, Cursor, SumTree};
  25use text::{
  26    locator::Locator,
  27    rope::TextDimension,
  28    subscription::{Subscription, Topic},
  29    Edit, Point, PointUtf16, TextSummary,
  30};
  31use theme::SyntaxTheme;
  32
  33const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  34
  35pub type ExcerptId = Locator;
  36
  37pub struct MultiBuffer {
  38    snapshot: RefCell<MultiBufferSnapshot>,
  39    buffers: RefCell<HashMap<usize, BufferState>>,
  40    used_excerpt_ids: SumTree<ExcerptId>,
  41    subscriptions: Topic,
  42    singleton: bool,
  43    replica_id: ReplicaId,
  44    history: History,
  45    title: Option<String>,
  46}
  47
  48#[derive(Clone)]
  49struct History {
  50    next_transaction_id: TransactionId,
  51    undo_stack: Vec<Transaction>,
  52    redo_stack: Vec<Transaction>,
  53    transaction_depth: usize,
  54    group_interval: Duration,
  55}
  56
  57#[derive(Clone)]
  58struct Transaction {
  59    id: TransactionId,
  60    buffer_transactions: HashMap<usize, text::TransactionId>,
  61    first_edit_at: Instant,
  62    last_edit_at: Instant,
  63    suppress_grouping: bool,
  64}
  65
  66pub trait ToOffset: 'static + fmt::Debug {
  67    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  68}
  69
  70pub trait ToPoint: 'static + fmt::Debug {
  71    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  72}
  73
  74pub trait ToPointUtf16: 'static + fmt::Debug {
  75    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
  76}
  77
  78struct BufferState {
  79    buffer: ModelHandle<Buffer>,
  80    last_version: clock::Global,
  81    last_parse_count: usize,
  82    last_selections_update_count: usize,
  83    last_diagnostics_update_count: usize,
  84    last_file_update_count: usize,
  85    excerpts: Vec<ExcerptId>,
  86    _subscriptions: [gpui::Subscription; 2],
  87}
  88
  89#[derive(Clone, Default)]
  90pub struct MultiBufferSnapshot {
  91    singleton: bool,
  92    excerpts: SumTree<Excerpt>,
  93    parse_count: usize,
  94    diagnostics_update_count: usize,
  95    trailing_excerpt_update_count: usize,
  96    is_dirty: bool,
  97    has_conflict: bool,
  98}
  99
 100pub struct ExcerptBoundary {
 101    pub id: ExcerptId,
 102    pub row: u32,
 103    pub buffer: BufferSnapshot,
 104    pub range: Range<text::Anchor>,
 105    pub starts_new_buffer: bool,
 106}
 107
 108#[derive(Clone)]
 109struct Excerpt {
 110    id: ExcerptId,
 111    buffer_id: usize,
 112    buffer: BufferSnapshot,
 113    range: Range<text::Anchor>,
 114    max_buffer_row: u32,
 115    text_summary: TextSummary,
 116    has_trailing_newline: bool,
 117}
 118
 119#[derive(Clone, Debug, Default)]
 120struct ExcerptSummary {
 121    excerpt_id: ExcerptId,
 122    max_buffer_row: u32,
 123    text: TextSummary,
 124}
 125
 126pub struct MultiBufferRows<'a> {
 127    buffer_row_range: Range<u32>,
 128    excerpts: Cursor<'a, Excerpt, Point>,
 129}
 130
 131pub struct MultiBufferChunks<'a> {
 132    range: Range<usize>,
 133    excerpts: Cursor<'a, Excerpt, usize>,
 134    excerpt_chunks: Option<ExcerptChunks<'a>>,
 135    language_aware: bool,
 136}
 137
 138pub struct MultiBufferBytes<'a> {
 139    range: Range<usize>,
 140    excerpts: Cursor<'a, Excerpt, usize>,
 141    excerpt_bytes: Option<ExcerptBytes<'a>>,
 142    chunk: &'a [u8],
 143}
 144
 145struct ExcerptChunks<'a> {
 146    content_chunks: BufferChunks<'a>,
 147    footer_height: usize,
 148}
 149
 150struct ExcerptBytes<'a> {
 151    content_bytes: language::rope::Bytes<'a>,
 152    footer_height: usize,
 153}
 154
 155impl MultiBuffer {
 156    pub fn new(replica_id: ReplicaId) -> Self {
 157        Self {
 158            snapshot: Default::default(),
 159            buffers: Default::default(),
 160            used_excerpt_ids: Default::default(),
 161            subscriptions: Default::default(),
 162            singleton: false,
 163            replica_id,
 164            history: History {
 165                next_transaction_id: Default::default(),
 166                undo_stack: Default::default(),
 167                redo_stack: Default::default(),
 168                transaction_depth: 0,
 169                group_interval: Duration::from_millis(300),
 170            },
 171            title: Default::default(),
 172        }
 173    }
 174
 175    pub fn clone(&self, new_cx: &mut ModelContext<Self>) -> Self {
 176        let mut buffers = HashMap::default();
 177        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 178            buffers.insert(
 179                *buffer_id,
 180                BufferState {
 181                    buffer: buffer_state.buffer.clone(),
 182                    last_version: buffer_state.last_version.clone(),
 183                    last_parse_count: buffer_state.last_parse_count,
 184                    last_selections_update_count: buffer_state.last_selections_update_count,
 185                    last_diagnostics_update_count: buffer_state.last_diagnostics_update_count,
 186                    last_file_update_count: buffer_state.last_file_update_count,
 187                    excerpts: buffer_state.excerpts.clone(),
 188                    _subscriptions: [
 189                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
 190                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
 191                    ],
 192                },
 193            );
 194        }
 195        Self {
 196            snapshot: RefCell::new(self.snapshot.borrow().clone()),
 197            buffers: RefCell::new(buffers),
 198            used_excerpt_ids: Default::default(),
 199            subscriptions: Default::default(),
 200            singleton: self.singleton,
 201            replica_id: self.replica_id,
 202            history: self.history.clone(),
 203            title: self.title.clone(),
 204        }
 205    }
 206
 207    pub fn with_title(mut self, title: String) -> Self {
 208        self.title = Some(title);
 209        self
 210    }
 211
 212    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 213        let mut this = Self::new(buffer.read(cx).replica_id());
 214        this.singleton = true;
 215        this.push_excerpts(buffer, [text::Anchor::MIN..text::Anchor::MAX], cx);
 216        this.snapshot.borrow_mut().singleton = true;
 217        this
 218    }
 219
 220    pub fn replica_id(&self) -> ReplicaId {
 221        self.replica_id
 222    }
 223
 224    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 225        self.sync(cx);
 226        self.snapshot.borrow().clone()
 227    }
 228
 229    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 230        self.sync(cx);
 231        self.snapshot.borrow()
 232    }
 233
 234    pub fn as_singleton(&self) -> Option<ModelHandle<Buffer>> {
 235        if self.singleton {
 236            return Some(
 237                self.buffers
 238                    .borrow()
 239                    .values()
 240                    .next()
 241                    .unwrap()
 242                    .buffer
 243                    .clone(),
 244            );
 245        } else {
 246            None
 247        }
 248    }
 249
 250    pub fn is_singleton(&self) -> bool {
 251        self.singleton
 252    }
 253
 254    pub fn subscribe(&mut self) -> Subscription {
 255        self.subscriptions.subscribe()
 256    }
 257
 258    pub fn edit<S, T>(&mut self, range: Range<S>, new_text: T, cx: &mut ModelContext<Self>)
 259    where
 260        S: ToOffset,
 261        T: Into<Arc<str>>,
 262    {
 263        self.edit_internal([(range, new_text)], false, cx);
 264    }
 265
 266    pub fn edit_batched<I, S, T>(&mut self, edits: I, cx: &mut ModelContext<Self>)
 267    where
 268        I: IntoIterator<Item = (Range<S>, T)>,
 269        S: ToOffset,
 270        T: Into<Arc<str>>,
 271    {
 272        self.edit_internal(edits, false, cx)
 273    }
 274
 275    pub fn edit_with_autoindent_batched<I, S, T>(&mut self, edits: I, cx: &mut ModelContext<Self>)
 276    where
 277        I: IntoIterator<Item = (Range<S>, T)>,
 278        S: ToOffset,
 279        T: Into<Arc<str>>,
 280    {
 281        self.edit_internal(edits, true, cx)
 282    }
 283
 284    pub fn edit_internal<I, S, T>(
 285        &mut self,
 286        edits_iter: I,
 287        autoindent: bool,
 288        cx: &mut ModelContext<Self>,
 289    ) where
 290        I: IntoIterator<Item = (Range<S>, T)>,
 291        S: ToOffset,
 292        T: Into<Arc<str>>,
 293    {
 294        if self.buffers.borrow().is_empty() {
 295            return;
 296        }
 297
 298        if let Some(buffer) = self.as_singleton() {
 299            let snapshot = self.read(cx);
 300            let edits = edits_iter.into_iter().map(|(range, new_text)| {
 301                (
 302                    range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot),
 303                    new_text,
 304                )
 305            });
 306            return buffer.update(cx, |buffer, cx| {
 307                let language_name = buffer.language().map(|language| language.name());
 308                let indent_size = cx.global::<Settings>().tab_size(language_name.as_deref());
 309                if autoindent {
 310                    buffer.edit_with_autoindent_batched(edits, indent_size, cx);
 311                } else {
 312                    buffer.edit_batched(edits, cx);
 313                }
 314            });
 315        }
 316
 317        let snapshot = self.read(cx);
 318        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, Arc<str>, bool)>> =
 319            Default::default();
 320        let mut cursor = snapshot.excerpts.cursor::<usize>();
 321        for (range, new_text) in edits_iter {
 322            let new_text: Arc<str> = new_text.into();
 323            let start = range.start.to_offset(&snapshot);
 324            let end = range.end.to_offset(&snapshot);
 325            cursor.seek(&start, Bias::Right, &());
 326            if cursor.item().is_none() && start == *cursor.start() {
 327                cursor.prev(&());
 328            }
 329            let start_excerpt = cursor.item().expect("start offset out of bounds");
 330            let start_overshoot = start - cursor.start();
 331            let buffer_start =
 332                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 333
 334            cursor.seek(&end, Bias::Right, &());
 335            if cursor.item().is_none() && end == *cursor.start() {
 336                cursor.prev(&());
 337            }
 338            let end_excerpt = cursor.item().expect("end offset out of bounds");
 339            let end_overshoot = end - cursor.start();
 340            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 341
 342            if start_excerpt.id == end_excerpt.id {
 343                buffer_edits
 344                    .entry(start_excerpt.buffer_id)
 345                    .or_insert(Vec::new())
 346                    .push((buffer_start..buffer_end, new_text, true));
 347            } else {
 348                let start_excerpt_range =
 349                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 350                let end_excerpt_range =
 351                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 352                buffer_edits
 353                    .entry(start_excerpt.buffer_id)
 354                    .or_insert(Vec::new())
 355                    .push((start_excerpt_range, new_text.clone(), true));
 356                buffer_edits
 357                    .entry(end_excerpt.buffer_id)
 358                    .or_insert(Vec::new())
 359                    .push((end_excerpt_range, new_text.clone(), false));
 360
 361                cursor.seek(&start, Bias::Right, &());
 362                cursor.next(&());
 363                while let Some(excerpt) = cursor.item() {
 364                    if excerpt.id == end_excerpt.id {
 365                        break;
 366                    }
 367                    buffer_edits
 368                        .entry(excerpt.buffer_id)
 369                        .or_insert(Vec::new())
 370                        .push((
 371                            excerpt.range.to_offset(&excerpt.buffer),
 372                            new_text.clone(),
 373                            false,
 374                        ));
 375                    cursor.next(&());
 376                }
 377            }
 378        }
 379
 380        for (buffer_id, mut edits) in buffer_edits {
 381            edits.sort_unstable_by_key(|(range, _, _)| range.start);
 382            self.buffers.borrow()[&buffer_id]
 383                .buffer
 384                .update(cx, |buffer, cx| {
 385                    let mut edits = edits.into_iter().peekable();
 386                    let mut insertions = Vec::new();
 387                    let mut deletions = Vec::new();
 388                    while let Some((mut range, mut new_text, mut is_insertion)) = edits.next() {
 389                        while let Some((next_range, next_new_text, next_is_insertion)) =
 390                            edits.peek()
 391                        {
 392                            if range.end >= next_range.start {
 393                                range.end = cmp::max(next_range.end, range.end);
 394                                new_text = format!("{new_text}{next_new_text}").into();
 395                                is_insertion |= *next_is_insertion;
 396                                edits.next();
 397                            } else {
 398                                break;
 399                            }
 400                        }
 401
 402                        if is_insertion {
 403                            insertions.push((
 404                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 405                                new_text,
 406                            ));
 407                        } else if !range.is_empty() {
 408                            deletions.push((
 409                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 410                                "",
 411                            ));
 412                        }
 413                    }
 414                    let language_name = buffer.language().map(|l| l.name());
 415                    let indent_size = cx.global::<Settings>().tab_size(language_name.as_deref());
 416
 417                    if autoindent {
 418                        buffer.edit_with_autoindent_batched(deletions, indent_size, cx);
 419                        buffer.edit_with_autoindent_batched(insertions, indent_size, cx);
 420                    } else {
 421                        buffer.edit_batched(deletions, cx);
 422                        buffer.edit_batched(insertions, cx);
 423                    }
 424                })
 425        }
 426    }
 427
 428    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 429        self.start_transaction_at(Instant::now(), cx)
 430    }
 431
 432    pub(crate) fn start_transaction_at(
 433        &mut self,
 434        now: Instant,
 435        cx: &mut ModelContext<Self>,
 436    ) -> Option<TransactionId> {
 437        if let Some(buffer) = self.as_singleton() {
 438            return buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 439        }
 440
 441        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 442            buffer.update(cx, |buffer, _| buffer.start_transaction_at(now));
 443        }
 444        self.history.start_transaction(now)
 445    }
 446
 447    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 448        self.end_transaction_at(Instant::now(), cx)
 449    }
 450
 451    pub(crate) fn end_transaction_at(
 452        &mut self,
 453        now: Instant,
 454        cx: &mut ModelContext<Self>,
 455    ) -> Option<TransactionId> {
 456        if let Some(buffer) = self.as_singleton() {
 457            return buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx));
 458        }
 459
 460        let mut buffer_transactions = HashMap::default();
 461        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 462            if let Some(transaction_id) =
 463                buffer.update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 464            {
 465                buffer_transactions.insert(buffer.id(), transaction_id);
 466            }
 467        }
 468
 469        if self.history.end_transaction(now, buffer_transactions) {
 470            let transaction_id = self.history.group().unwrap();
 471            Some(transaction_id)
 472        } else {
 473            None
 474        }
 475    }
 476
 477    pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
 478        self.history.finalize_last_transaction();
 479        for BufferState { buffer, .. } in self.buffers.borrow().values() {
 480            buffer.update(cx, |buffer, _| {
 481                buffer.finalize_last_transaction();
 482            });
 483        }
 484    }
 485
 486    pub fn push_transaction<'a, T>(&mut self, buffer_transactions: T)
 487    where
 488        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
 489    {
 490        self.history
 491            .push_transaction(buffer_transactions, Instant::now());
 492        self.history.finalize_last_transaction();
 493    }
 494
 495    pub fn set_active_selections(
 496        &mut self,
 497        selections: &[Selection<Anchor>],
 498        cx: &mut ModelContext<Self>,
 499    ) {
 500        let mut selections_by_buffer: HashMap<usize, Vec<Selection<text::Anchor>>> =
 501            Default::default();
 502        let snapshot = self.read(cx);
 503        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 504        for selection in selections {
 505            cursor.seek(&Some(&selection.start.excerpt_id), Bias::Left, &());
 506            while let Some(excerpt) = cursor.item() {
 507                if excerpt.id > selection.end.excerpt_id {
 508                    break;
 509                }
 510
 511                let mut start = excerpt.range.start.clone();
 512                let mut end = excerpt.range.end.clone();
 513                if excerpt.id == selection.start.excerpt_id {
 514                    start = selection.start.text_anchor.clone();
 515                }
 516                if excerpt.id == selection.end.excerpt_id {
 517                    end = selection.end.text_anchor.clone();
 518                }
 519                selections_by_buffer
 520                    .entry(excerpt.buffer_id)
 521                    .or_default()
 522                    .push(Selection {
 523                        id: selection.id,
 524                        start,
 525                        end,
 526                        reversed: selection.reversed,
 527                        goal: selection.goal,
 528                    });
 529
 530                cursor.next(&());
 531            }
 532        }
 533
 534        for (buffer_id, buffer_state) in self.buffers.borrow().iter() {
 535            if !selections_by_buffer.contains_key(buffer_id) {
 536                buffer_state
 537                    .buffer
 538                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 539            }
 540        }
 541
 542        for (buffer_id, mut selections) in selections_by_buffer {
 543            self.buffers.borrow()[&buffer_id]
 544                .buffer
 545                .update(cx, |buffer, cx| {
 546                    selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
 547                    let mut selections = selections.into_iter().peekable();
 548                    let merged_selections = Arc::from_iter(iter::from_fn(|| {
 549                        let mut selection = selections.next()?;
 550                        while let Some(next_selection) = selections.peek() {
 551                            if selection.end.cmp(&next_selection.start, buffer).is_ge() {
 552                                let next_selection = selections.next().unwrap();
 553                                if next_selection.end.cmp(&selection.end, buffer).is_ge() {
 554                                    selection.end = next_selection.end;
 555                                }
 556                            } else {
 557                                break;
 558                            }
 559                        }
 560                        Some(selection)
 561                    }));
 562                    buffer.set_active_selections(merged_selections, cx);
 563                });
 564        }
 565    }
 566
 567    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 568        for buffer in self.buffers.borrow().values() {
 569            buffer
 570                .buffer
 571                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 572        }
 573    }
 574
 575    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 576        if let Some(buffer) = self.as_singleton() {
 577            return buffer.update(cx, |buffer, cx| buffer.undo(cx));
 578        }
 579
 580        while let Some(transaction) = self.history.pop_undo() {
 581            let mut undone = false;
 582            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 583                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 584                    undone |= buffer.update(cx, |buffer, cx| {
 585                        let undo_to = *buffer_transaction_id;
 586                        if let Some(entry) = buffer.peek_undo_stack() {
 587                            *buffer_transaction_id = entry.transaction_id();
 588                        }
 589                        buffer.undo_to_transaction(undo_to, cx)
 590                    });
 591                }
 592            }
 593
 594            if undone {
 595                return Some(transaction.id);
 596            }
 597        }
 598
 599        None
 600    }
 601
 602    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 603        if let Some(buffer) = self.as_singleton() {
 604            return buffer.update(cx, |buffer, cx| buffer.redo(cx));
 605        }
 606
 607        while let Some(transaction) = self.history.pop_redo() {
 608            let mut redone = false;
 609            for (buffer_id, buffer_transaction_id) in &mut transaction.buffer_transactions {
 610                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(&buffer_id) {
 611                    redone |= buffer.update(cx, |buffer, cx| {
 612                        let redo_to = *buffer_transaction_id;
 613                        if let Some(entry) = buffer.peek_redo_stack() {
 614                            *buffer_transaction_id = entry.transaction_id();
 615                        }
 616                        buffer.redo_to_transaction(redo_to, cx)
 617                    });
 618                }
 619            }
 620
 621            if redone {
 622                return Some(transaction.id);
 623            }
 624        }
 625
 626        None
 627    }
 628
 629    pub fn push_excerpts<O>(
 630        &mut self,
 631        buffer: ModelHandle<Buffer>,
 632        ranges: impl IntoIterator<Item = Range<O>>,
 633        cx: &mut ModelContext<Self>,
 634    ) -> Vec<ExcerptId>
 635    where
 636        O: text::ToOffset,
 637    {
 638        self.insert_excerpts_after(&ExcerptId::max(), buffer, ranges, cx)
 639    }
 640
 641    pub fn push_excerpts_with_context_lines<O>(
 642        &mut self,
 643        buffer: ModelHandle<Buffer>,
 644        ranges: Vec<Range<O>>,
 645        context_line_count: u32,
 646        cx: &mut ModelContext<Self>,
 647    ) -> Vec<Range<Anchor>>
 648    where
 649        O: text::ToPoint + text::ToOffset,
 650    {
 651        let buffer_id = buffer.id();
 652        let buffer_snapshot = buffer.read(cx).snapshot();
 653        let max_point = buffer_snapshot.max_point();
 654
 655        let mut range_counts = Vec::new();
 656        let mut excerpt_ranges = Vec::new();
 657        let mut range_iter = ranges
 658            .iter()
 659            .map(|range| {
 660                range.start.to_point(&buffer_snapshot)..range.end.to_point(&buffer_snapshot)
 661            })
 662            .peekable();
 663        while let Some(range) = range_iter.next() {
 664            let excerpt_start = Point::new(range.start.row.saturating_sub(context_line_count), 0);
 665            let mut excerpt_end =
 666                Point::new(range.end.row + 1 + context_line_count, 0).min(max_point);
 667            let mut ranges_in_excerpt = 1;
 668
 669            while let Some(next_range) = range_iter.peek() {
 670                if next_range.start.row <= excerpt_end.row + context_line_count {
 671                    excerpt_end =
 672                        Point::new(next_range.end.row + 1 + context_line_count, 0).min(max_point);
 673                    ranges_in_excerpt += 1;
 674                    range_iter.next();
 675                } else {
 676                    break;
 677                }
 678            }
 679
 680            excerpt_ranges.push(excerpt_start..excerpt_end);
 681            range_counts.push(ranges_in_excerpt);
 682        }
 683
 684        let excerpt_ids = self.push_excerpts(buffer, excerpt_ranges, cx);
 685
 686        let mut anchor_ranges = Vec::new();
 687        let mut ranges = ranges.into_iter();
 688        for (excerpt_id, range_count) in excerpt_ids.into_iter().zip(range_counts.into_iter()) {
 689            anchor_ranges.extend(ranges.by_ref().take(range_count).map(|range| {
 690                let start = Anchor {
 691                    buffer_id: Some(buffer_id),
 692                    excerpt_id: excerpt_id.clone(),
 693                    text_anchor: buffer_snapshot.anchor_after(range.start),
 694                };
 695                let end = Anchor {
 696                    buffer_id: Some(buffer_id),
 697                    excerpt_id: excerpt_id.clone(),
 698                    text_anchor: buffer_snapshot.anchor_after(range.end),
 699                };
 700                start..end
 701            }))
 702        }
 703        anchor_ranges
 704    }
 705
 706    pub fn insert_excerpts_after<O>(
 707        &mut self,
 708        prev_excerpt_id: &ExcerptId,
 709        buffer: ModelHandle<Buffer>,
 710        ranges: impl IntoIterator<Item = Range<O>>,
 711        cx: &mut ModelContext<Self>,
 712    ) -> Vec<ExcerptId>
 713    where
 714        O: text::ToOffset,
 715    {
 716        assert_eq!(self.history.transaction_depth, 0);
 717        let mut ranges = ranges.into_iter().peekable();
 718        if ranges.peek().is_none() {
 719            return Default::default();
 720        }
 721
 722        self.sync(cx);
 723
 724        let buffer_id = buffer.id();
 725        let buffer_snapshot = buffer.read(cx).snapshot();
 726
 727        let mut buffers = self.buffers.borrow_mut();
 728        let buffer_state = buffers.entry(buffer_id).or_insert_with(|| BufferState {
 729            last_version: buffer_snapshot.version().clone(),
 730            last_parse_count: buffer_snapshot.parse_count(),
 731            last_selections_update_count: buffer_snapshot.selections_update_count(),
 732            last_diagnostics_update_count: buffer_snapshot.diagnostics_update_count(),
 733            last_file_update_count: buffer_snapshot.file_update_count(),
 734            excerpts: Default::default(),
 735            _subscriptions: [
 736                cx.observe(&buffer, |_, _, cx| cx.notify()),
 737                cx.subscribe(&buffer, Self::on_buffer_event),
 738            ],
 739            buffer,
 740        });
 741
 742        let mut snapshot = self.snapshot.borrow_mut();
 743        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 744        let mut new_excerpts = cursor.slice(&Some(prev_excerpt_id), Bias::Right, &());
 745
 746        let edit_start = new_excerpts.summary().text.bytes;
 747        new_excerpts.update_last(
 748            |excerpt| {
 749                excerpt.has_trailing_newline = true;
 750            },
 751            &(),
 752        );
 753
 754        let mut used_cursor = self.used_excerpt_ids.cursor::<Locator>();
 755        used_cursor.seek(prev_excerpt_id, Bias::Right, &());
 756        let mut prev_id = if let Some(excerpt_id) = used_cursor.prev_item() {
 757            excerpt_id.clone()
 758        } else {
 759            ExcerptId::min()
 760        };
 761        let next_id = if let Some(excerpt_id) = used_cursor.item() {
 762            excerpt_id.clone()
 763        } else {
 764            ExcerptId::max()
 765        };
 766        drop(used_cursor);
 767
 768        let mut ids = Vec::new();
 769        while let Some(range) = ranges.next() {
 770            let id = ExcerptId::between(&prev_id, &next_id);
 771            if let Err(ix) = buffer_state.excerpts.binary_search(&id) {
 772                buffer_state.excerpts.insert(ix, id.clone());
 773            }
 774            let range = buffer_snapshot.anchor_before(&range.start)
 775                ..buffer_snapshot.anchor_after(&range.end);
 776            let excerpt = Excerpt::new(
 777                id.clone(),
 778                buffer_id,
 779                buffer_snapshot.clone(),
 780                range,
 781                ranges.peek().is_some() || cursor.item().is_some(),
 782            );
 783            new_excerpts.push(excerpt, &());
 784            prev_id = id.clone();
 785            ids.push(id);
 786        }
 787        self.used_excerpt_ids.edit(
 788            ids.iter().cloned().map(sum_tree::Edit::Insert).collect(),
 789            &(),
 790        );
 791
 792        let edit_end = new_excerpts.summary().text.bytes;
 793
 794        let suffix = cursor.suffix(&());
 795        let changed_trailing_excerpt = suffix.is_empty();
 796        new_excerpts.push_tree(suffix, &());
 797        drop(cursor);
 798        snapshot.excerpts = new_excerpts;
 799        if changed_trailing_excerpt {
 800            snapshot.trailing_excerpt_update_count += 1;
 801        }
 802
 803        self.subscriptions.publish_mut([Edit {
 804            old: edit_start..edit_start,
 805            new: edit_start..edit_end,
 806        }]);
 807        cx.emit(Event::Edited);
 808        cx.notify();
 809        ids
 810    }
 811
 812    pub fn clear(&mut self, cx: &mut ModelContext<Self>) {
 813        self.sync(cx);
 814        self.buffers.borrow_mut().clear();
 815        let mut snapshot = self.snapshot.borrow_mut();
 816        let prev_len = snapshot.len();
 817        snapshot.excerpts = Default::default();
 818        snapshot.trailing_excerpt_update_count += 1;
 819        snapshot.is_dirty = false;
 820        snapshot.has_conflict = false;
 821
 822        self.subscriptions.publish_mut([Edit {
 823            old: 0..prev_len,
 824            new: 0..0,
 825        }]);
 826        cx.emit(Event::Edited);
 827        cx.notify();
 828    }
 829
 830    pub fn excerpts_for_buffer(
 831        &self,
 832        buffer: &ModelHandle<Buffer>,
 833        cx: &AppContext,
 834    ) -> Vec<(ExcerptId, Range<text::Anchor>)> {
 835        let mut excerpts = Vec::new();
 836        let snapshot = self.read(cx);
 837        let buffers = self.buffers.borrow();
 838        let mut cursor = snapshot.excerpts.cursor::<Option<&ExcerptId>>();
 839        for excerpt_id in buffers
 840            .get(&buffer.id())
 841            .map(|state| &state.excerpts)
 842            .into_iter()
 843            .flatten()
 844        {
 845            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
 846            if let Some(excerpt) = cursor.item() {
 847                if excerpt.id == *excerpt_id {
 848                    excerpts.push((excerpt.id.clone(), excerpt.range.clone()));
 849                }
 850            }
 851        }
 852
 853        excerpts
 854    }
 855
 856    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
 857        self.buffers
 858            .borrow()
 859            .values()
 860            .flat_map(|state| state.excerpts.iter().cloned())
 861            .collect()
 862    }
 863
 864    pub fn excerpt_containing(
 865        &self,
 866        position: impl ToOffset,
 867        cx: &AppContext,
 868    ) -> Option<(ModelHandle<Buffer>, Range<text::Anchor>)> {
 869        let snapshot = self.read(cx);
 870        let position = position.to_offset(&snapshot);
 871
 872        let mut cursor = snapshot.excerpts.cursor::<usize>();
 873        cursor.seek(&position, Bias::Right, &());
 874        cursor.item().map(|excerpt| {
 875            (
 876                self.buffers
 877                    .borrow()
 878                    .get(&excerpt.buffer_id)
 879                    .unwrap()
 880                    .buffer
 881                    .clone(),
 882                excerpt.range.clone(),
 883            )
 884        })
 885    }
 886
 887    // If point is at the end of the buffer, the last excerpt is returned
 888    pub fn point_to_buffer_offset<'a, T: ToOffset>(
 889        &'a self,
 890        point: T,
 891        cx: &AppContext,
 892    ) -> Option<(ModelHandle<Buffer>, usize)> {
 893        let snapshot = self.read(cx);
 894        let offset = point.to_offset(&snapshot);
 895        let mut cursor = snapshot.excerpts.cursor::<usize>();
 896        cursor.seek(&offset, Bias::Right, &());
 897        if cursor.item().is_none() {
 898            cursor.prev(&());
 899        }
 900
 901        cursor.item().map(|excerpt| {
 902            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 903            let buffer_point = excerpt_start + offset - *cursor.start();
 904            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 905
 906            (buffer, buffer_point)
 907        })
 908    }
 909
 910    pub fn range_to_buffer_ranges<'a, T: ToOffset>(
 911        &'a self,
 912        range: Range<T>,
 913        cx: &AppContext,
 914    ) -> Vec<(ModelHandle<Buffer>, Range<usize>)> {
 915        let snapshot = self.read(cx);
 916        let start = range.start.to_offset(&snapshot);
 917        let end = range.end.to_offset(&snapshot);
 918
 919        let mut result = Vec::new();
 920        let mut cursor = snapshot.excerpts.cursor::<usize>();
 921        cursor.seek(&start, Bias::Right, &());
 922        while let Some(excerpt) = cursor.item() {
 923            if *cursor.start() > end {
 924                break;
 925            }
 926
 927            let mut end_before_newline = cursor.end(&());
 928            if excerpt.has_trailing_newline {
 929                end_before_newline -= 1;
 930            }
 931            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 932            let start = excerpt_start + (cmp::max(start, *cursor.start()) - *cursor.start());
 933            let end = excerpt_start + (cmp::min(end, end_before_newline) - *cursor.start());
 934            let buffer = self.buffers.borrow()[&excerpt.buffer_id].buffer.clone();
 935            result.push((buffer, start..end));
 936            cursor.next(&());
 937        }
 938
 939        result
 940    }
 941
 942    pub fn remove_excerpts<'a>(
 943        &mut self,
 944        excerpt_ids: impl IntoIterator<Item = &'a ExcerptId>,
 945        cx: &mut ModelContext<Self>,
 946    ) {
 947        self.sync(cx);
 948        let mut buffers = self.buffers.borrow_mut();
 949        let mut snapshot = self.snapshot.borrow_mut();
 950        let mut new_excerpts = SumTree::new();
 951        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 952        let mut edits = Vec::new();
 953        let mut excerpt_ids = excerpt_ids.into_iter().peekable();
 954
 955        while let Some(mut excerpt_id) = excerpt_ids.next() {
 956            // Seek to the next excerpt to remove, preserving any preceding excerpts.
 957            new_excerpts.push_tree(cursor.slice(&Some(excerpt_id), Bias::Left, &()), &());
 958            if let Some(mut excerpt) = cursor.item() {
 959                if excerpt.id != *excerpt_id {
 960                    continue;
 961                }
 962                let mut old_start = cursor.start().1;
 963
 964                // Skip over the removed excerpt.
 965                loop {
 966                    if let Some(buffer_state) = buffers.get_mut(&excerpt.buffer_id) {
 967                        buffer_state.excerpts.retain(|id| id != excerpt_id);
 968                        if buffer_state.excerpts.is_empty() {
 969                            buffers.remove(&excerpt.buffer_id);
 970                        }
 971                    }
 972                    cursor.next(&());
 973
 974                    // Skip over any subsequent excerpts that are also removed.
 975                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
 976                        if let Some(next_excerpt) = cursor.item() {
 977                            if next_excerpt.id == *next_excerpt_id {
 978                                excerpt = next_excerpt;
 979                                excerpt_id = excerpt_ids.next().unwrap();
 980                                continue;
 981                            }
 982                        }
 983                    }
 984
 985                    break;
 986                }
 987
 988                // When removing the last excerpt, remove the trailing newline from
 989                // the previous excerpt.
 990                if cursor.item().is_none() && old_start > 0 {
 991                    old_start -= 1;
 992                    new_excerpts.update_last(|e| e.has_trailing_newline = false, &());
 993                }
 994
 995                // Push an edit for the removal of this run of excerpts.
 996                let old_end = cursor.start().1;
 997                let new_start = new_excerpts.summary().text.bytes;
 998                edits.push(Edit {
 999                    old: old_start..old_end,
1000                    new: new_start..new_start,
1001                });
1002            }
1003        }
1004        let suffix = cursor.suffix(&());
1005        let changed_trailing_excerpt = suffix.is_empty();
1006        new_excerpts.push_tree(suffix, &());
1007        drop(cursor);
1008        snapshot.excerpts = new_excerpts;
1009        if changed_trailing_excerpt {
1010            snapshot.trailing_excerpt_update_count += 1;
1011        }
1012
1013        self.subscriptions.publish_mut(edits);
1014        cx.emit(Event::Edited);
1015        cx.notify();
1016    }
1017
1018    pub fn text_anchor_for_position<'a, T: ToOffset>(
1019        &'a self,
1020        position: T,
1021        cx: &AppContext,
1022    ) -> Option<(ModelHandle<Buffer>, language::Anchor)> {
1023        let snapshot = self.read(cx);
1024        let anchor = snapshot.anchor_before(position);
1025        let buffer = self
1026            .buffers
1027            .borrow()
1028            .get(&anchor.buffer_id?)?
1029            .buffer
1030            .clone();
1031        Some((buffer, anchor.text_anchor))
1032    }
1033
1034    fn on_buffer_event(
1035        &mut self,
1036        _: ModelHandle<Buffer>,
1037        event: &Event,
1038        cx: &mut ModelContext<Self>,
1039    ) {
1040        cx.emit(event.clone());
1041    }
1042
1043    pub fn all_buffers(&self) -> HashSet<ModelHandle<Buffer>> {
1044        self.buffers
1045            .borrow()
1046            .values()
1047            .map(|state| state.buffer.clone())
1048            .collect()
1049    }
1050
1051    pub fn buffer(&self, buffer_id: usize) -> Option<ModelHandle<Buffer>> {
1052        self.buffers
1053            .borrow()
1054            .get(&buffer_id)
1055            .map(|state| state.buffer.clone())
1056    }
1057
1058    pub fn save(&mut self, cx: &mut ModelContext<Self>) -> Task<Result<()>> {
1059        let mut save_tasks = Vec::new();
1060        for BufferState { buffer, .. } in self.buffers.borrow().values() {
1061            save_tasks.push(buffer.update(cx, |buffer, cx| buffer.save(cx)));
1062        }
1063
1064        cx.spawn(|_, _| async move {
1065            for save in save_tasks {
1066                save.await?;
1067            }
1068            Ok(())
1069        })
1070    }
1071
1072    pub fn is_completion_trigger<T>(&self, position: T, text: &str, cx: &AppContext) -> bool
1073    where
1074        T: ToOffset,
1075    {
1076        let mut chars = text.chars();
1077        let char = if let Some(char) = chars.next() {
1078            char
1079        } else {
1080            return false;
1081        };
1082        if chars.next().is_some() {
1083            return false;
1084        }
1085
1086        if char.is_alphanumeric() || char == '_' {
1087            return true;
1088        }
1089
1090        let snapshot = self.snapshot(cx);
1091        let anchor = snapshot.anchor_before(position);
1092        anchor
1093            .buffer_id
1094            .and_then(|buffer_id| {
1095                let buffer = self.buffers.borrow().get(&buffer_id)?.buffer.clone();
1096                Some(
1097                    buffer
1098                        .read(cx)
1099                        .completion_triggers()
1100                        .iter()
1101                        .any(|string| string == text),
1102                )
1103            })
1104            .unwrap_or(false)
1105    }
1106
1107    pub fn language_at<'a, T: ToOffset>(
1108        &self,
1109        point: T,
1110        cx: &'a AppContext,
1111    ) -> Option<&'a Arc<Language>> {
1112        self.point_to_buffer_offset(point, cx)
1113            .and_then(|(buffer, _)| buffer.read(cx).language())
1114    }
1115
1116    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
1117        self.as_singleton()?.read(cx).file()
1118    }
1119
1120    pub fn title(&self, cx: &AppContext) -> String {
1121        if let Some(title) = self.title.clone() {
1122            title
1123        } else if let Some(file) = self.file(cx) {
1124            file.file_name(cx).to_string_lossy().into()
1125        } else {
1126            "untitled".into()
1127        }
1128    }
1129
1130    #[cfg(test)]
1131    pub fn is_parsing(&self, cx: &AppContext) -> bool {
1132        self.as_singleton().unwrap().read(cx).is_parsing()
1133    }
1134
1135    fn sync(&self, cx: &AppContext) {
1136        let mut snapshot = self.snapshot.borrow_mut();
1137        let mut excerpts_to_edit = Vec::new();
1138        let mut reparsed = false;
1139        let mut diagnostics_updated = false;
1140        let mut is_dirty = false;
1141        let mut has_conflict = false;
1142        let mut buffers = self.buffers.borrow_mut();
1143        for buffer_state in buffers.values_mut() {
1144            let buffer = buffer_state.buffer.read(cx);
1145            let version = buffer.version();
1146            let parse_count = buffer.parse_count();
1147            let selections_update_count = buffer.selections_update_count();
1148            let diagnostics_update_count = buffer.diagnostics_update_count();
1149            let file_update_count = buffer.file_update_count();
1150
1151            let buffer_edited = version.changed_since(&buffer_state.last_version);
1152            let buffer_reparsed = parse_count > buffer_state.last_parse_count;
1153            let buffer_selections_updated =
1154                selections_update_count > buffer_state.last_selections_update_count;
1155            let buffer_diagnostics_updated =
1156                diagnostics_update_count > buffer_state.last_diagnostics_update_count;
1157            let buffer_file_updated = file_update_count > buffer_state.last_file_update_count;
1158            if buffer_edited
1159                || buffer_reparsed
1160                || buffer_selections_updated
1161                || buffer_diagnostics_updated
1162                || buffer_file_updated
1163            {
1164                buffer_state.last_version = version;
1165                buffer_state.last_parse_count = parse_count;
1166                buffer_state.last_selections_update_count = selections_update_count;
1167                buffer_state.last_diagnostics_update_count = diagnostics_update_count;
1168                buffer_state.last_file_update_count = file_update_count;
1169                excerpts_to_edit.extend(
1170                    buffer_state
1171                        .excerpts
1172                        .iter()
1173                        .map(|excerpt_id| (excerpt_id, buffer_state.buffer.clone(), buffer_edited)),
1174                );
1175            }
1176
1177            reparsed |= buffer_reparsed;
1178            diagnostics_updated |= buffer_diagnostics_updated;
1179            is_dirty |= buffer.is_dirty();
1180            has_conflict |= buffer.has_conflict();
1181        }
1182        if reparsed {
1183            snapshot.parse_count += 1;
1184        }
1185        if diagnostics_updated {
1186            snapshot.diagnostics_update_count += 1;
1187        }
1188        snapshot.is_dirty = is_dirty;
1189        snapshot.has_conflict = has_conflict;
1190
1191        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
1192
1193        let mut edits = Vec::new();
1194        let mut new_excerpts = SumTree::new();
1195        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
1196
1197        for (id, buffer, buffer_edited) in excerpts_to_edit {
1198            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
1199            let old_excerpt = cursor.item().unwrap();
1200            let buffer_id = buffer.id();
1201            let buffer = buffer.read(cx);
1202
1203            let mut new_excerpt;
1204            if buffer_edited {
1205                edits.extend(
1206                    buffer
1207                        .edits_since_in_range::<usize>(
1208                            old_excerpt.buffer.version(),
1209                            old_excerpt.range.clone(),
1210                        )
1211                        .map(|mut edit| {
1212                            let excerpt_old_start = cursor.start().1;
1213                            let excerpt_new_start = new_excerpts.summary().text.bytes;
1214                            edit.old.start += excerpt_old_start;
1215                            edit.old.end += excerpt_old_start;
1216                            edit.new.start += excerpt_new_start;
1217                            edit.new.end += excerpt_new_start;
1218                            edit
1219                        }),
1220                );
1221
1222                new_excerpt = Excerpt::new(
1223                    id.clone(),
1224                    buffer_id,
1225                    buffer.snapshot(),
1226                    old_excerpt.range.clone(),
1227                    old_excerpt.has_trailing_newline,
1228                );
1229            } else {
1230                new_excerpt = old_excerpt.clone();
1231                new_excerpt.buffer = buffer.snapshot();
1232            }
1233
1234            new_excerpts.push(new_excerpt, &());
1235            cursor.next(&());
1236        }
1237        new_excerpts.push_tree(cursor.suffix(&()), &());
1238
1239        drop(cursor);
1240        snapshot.excerpts = new_excerpts;
1241
1242        self.subscriptions.publish(edits);
1243    }
1244}
1245
1246#[cfg(any(test, feature = "test-support"))]
1247impl MultiBuffer {
1248    pub fn build_simple(text: &str, cx: &mut gpui::MutableAppContext) -> ModelHandle<Self> {
1249        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
1250        cx.add_model(|cx| Self::singleton(buffer, cx))
1251    }
1252
1253    pub fn build_random(
1254        rng: &mut impl rand::Rng,
1255        cx: &mut gpui::MutableAppContext,
1256    ) -> ModelHandle<Self> {
1257        cx.add_model(|cx| {
1258            let mut multibuffer = MultiBuffer::new(0);
1259            let mutation_count = rng.gen_range(1..=5);
1260            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
1261            multibuffer
1262        })
1263    }
1264
1265    pub fn randomly_edit(
1266        &mut self,
1267        rng: &mut impl rand::Rng,
1268        edit_count: usize,
1269        cx: &mut ModelContext<Self>,
1270    ) {
1271        use text::RandomCharIter;
1272
1273        let snapshot = self.read(cx);
1274        let mut edits: Vec<(Range<usize>, Arc<str>)> = Vec::new();
1275        let mut last_end = None;
1276        for _ in 0..edit_count {
1277            if last_end.map_or(false, |last_end| last_end >= snapshot.len()) {
1278                break;
1279            }
1280
1281            let new_start = last_end.map_or(0, |last_end| last_end + 1);
1282            let end = snapshot.clip_offset(rng.gen_range(new_start..=snapshot.len()), Bias::Right);
1283            let start = snapshot.clip_offset(rng.gen_range(new_start..=end), Bias::Right);
1284            last_end = Some(end);
1285            let range = start..end;
1286
1287            let new_text_len = rng.gen_range(0..10);
1288            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
1289
1290            edits.push((range, new_text.into()));
1291        }
1292        log::info!("mutating multi-buffer with {:?}", edits);
1293        drop(snapshot);
1294
1295        self.edit_batched(edits, cx);
1296    }
1297
1298    pub fn randomly_edit_excerpts(
1299        &mut self,
1300        rng: &mut impl rand::Rng,
1301        mutation_count: usize,
1302        cx: &mut ModelContext<Self>,
1303    ) {
1304        use rand::prelude::*;
1305        use std::env;
1306        use text::RandomCharIter;
1307
1308        let max_excerpts = env::var("MAX_EXCERPTS")
1309            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
1310            .unwrap_or(5);
1311
1312        let mut buffers = Vec::new();
1313        for _ in 0..mutation_count {
1314            if rng.gen_bool(0.05) {
1315                log::info!("Clearing multi-buffer");
1316                self.clear(cx);
1317                continue;
1318            }
1319
1320            let excerpt_ids = self
1321                .buffers
1322                .borrow()
1323                .values()
1324                .flat_map(|b| &b.excerpts)
1325                .cloned()
1326                .collect::<Vec<_>>();
1327            if excerpt_ids.len() == 0 || (rng.gen() && excerpt_ids.len() < max_excerpts) {
1328                let buffer_handle = if rng.gen() || self.buffers.borrow().is_empty() {
1329                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
1330                    buffers.push(cx.add_model(|cx| Buffer::new(0, text, cx)));
1331                    let buffer = buffers.last().unwrap();
1332                    log::info!(
1333                        "Creating new buffer {} with text: {:?}",
1334                        buffer.id(),
1335                        buffer.read(cx).text()
1336                    );
1337                    buffers.last().unwrap().clone()
1338                } else {
1339                    self.buffers
1340                        .borrow()
1341                        .values()
1342                        .choose(rng)
1343                        .unwrap()
1344                        .buffer
1345                        .clone()
1346                };
1347
1348                let buffer = buffer_handle.read(cx);
1349                let buffer_text = buffer.text();
1350                let ranges = (0..rng.gen_range(0..5))
1351                    .map(|_| {
1352                        let end_ix =
1353                            buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1354                        let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1355                        start_ix..end_ix
1356                    })
1357                    .collect::<Vec<_>>();
1358                log::info!(
1359                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
1360                    buffer_handle.id(),
1361                    ranges,
1362                    ranges
1363                        .iter()
1364                        .map(|range| &buffer_text[range.clone()])
1365                        .collect::<Vec<_>>()
1366                );
1367
1368                let excerpt_id = self.push_excerpts(buffer_handle.clone(), ranges, cx);
1369                log::info!("Inserted with id: {:?}", excerpt_id);
1370            } else {
1371                let remove_count = rng.gen_range(1..=excerpt_ids.len());
1372                let mut excerpts_to_remove = excerpt_ids
1373                    .choose_multiple(rng, remove_count)
1374                    .cloned()
1375                    .collect::<Vec<_>>();
1376                excerpts_to_remove.sort();
1377                log::info!("Removing excerpts {:?}", excerpts_to_remove);
1378                self.remove_excerpts(&excerpts_to_remove, cx);
1379            }
1380        }
1381    }
1382
1383    pub fn randomly_mutate(
1384        &mut self,
1385        rng: &mut impl rand::Rng,
1386        mutation_count: usize,
1387        cx: &mut ModelContext<Self>,
1388    ) {
1389        if rng.gen_bool(0.7) || self.singleton {
1390            self.randomly_edit(rng, mutation_count, cx);
1391        } else {
1392            self.randomly_edit_excerpts(rng, mutation_count, cx);
1393        }
1394    }
1395}
1396
1397impl Entity for MultiBuffer {
1398    type Event = language::Event;
1399}
1400
1401impl MultiBufferSnapshot {
1402    pub fn text(&self) -> String {
1403        self.chunks(0..self.len(), false)
1404            .map(|chunk| chunk.text)
1405            .collect()
1406    }
1407
1408    pub fn reversed_chars_at<'a, T: ToOffset>(
1409        &'a self,
1410        position: T,
1411    ) -> impl Iterator<Item = char> + 'a {
1412        let mut offset = position.to_offset(self);
1413        let mut cursor = self.excerpts.cursor::<usize>();
1414        cursor.seek(&offset, Bias::Left, &());
1415        let mut excerpt_chunks = cursor.item().map(|excerpt| {
1416            let end_before_footer = cursor.start() + excerpt.text_summary.bytes;
1417            let start = excerpt.range.start.to_offset(&excerpt.buffer);
1418            let end = start + (cmp::min(offset, end_before_footer) - cursor.start());
1419            excerpt.buffer.reversed_chunks_in_range(start..end)
1420        });
1421        iter::from_fn(move || {
1422            if offset == *cursor.start() {
1423                cursor.prev(&());
1424                let excerpt = cursor.item()?;
1425                excerpt_chunks = Some(
1426                    excerpt
1427                        .buffer
1428                        .reversed_chunks_in_range(excerpt.range.clone()),
1429                );
1430            }
1431
1432            let excerpt = cursor.item().unwrap();
1433            if offset == cursor.end(&()) && excerpt.has_trailing_newline {
1434                offset -= 1;
1435                Some("\n")
1436            } else {
1437                let chunk = excerpt_chunks.as_mut().unwrap().next().unwrap();
1438                offset -= chunk.len();
1439                Some(chunk)
1440            }
1441        })
1442        .flat_map(|c| c.chars().rev())
1443    }
1444
1445    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
1446        let offset = position.to_offset(self);
1447        self.text_for_range(offset..self.len())
1448            .flat_map(|chunk| chunk.chars())
1449    }
1450
1451    pub fn text_for_range<'a, T: ToOffset>(
1452        &'a self,
1453        range: Range<T>,
1454    ) -> impl Iterator<Item = &'a str> {
1455        self.chunks(range, false).map(|chunk| chunk.text)
1456    }
1457
1458    pub fn is_line_blank(&self, row: u32) -> bool {
1459        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
1460            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
1461    }
1462
1463    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
1464    where
1465        T: ToOffset,
1466    {
1467        let position = position.to_offset(self);
1468        position == self.clip_offset(position, Bias::Left)
1469            && self
1470                .bytes_in_range(position..self.len())
1471                .flatten()
1472                .copied()
1473                .take(needle.len())
1474                .eq(needle.bytes())
1475    }
1476
1477    pub fn surrounding_word<T: ToOffset>(&self, start: T) -> (Range<usize>, Option<CharKind>) {
1478        let mut start = start.to_offset(self);
1479        let mut end = start;
1480        let mut next_chars = self.chars_at(start).peekable();
1481        let mut prev_chars = self.reversed_chars_at(start).peekable();
1482        let word_kind = cmp::max(
1483            prev_chars.peek().copied().map(char_kind),
1484            next_chars.peek().copied().map(char_kind),
1485        );
1486
1487        for ch in prev_chars {
1488            if Some(char_kind(ch)) == word_kind && ch != '\n' {
1489                start -= ch.len_utf8();
1490            } else {
1491                break;
1492            }
1493        }
1494
1495        for ch in next_chars {
1496            if Some(char_kind(ch)) == word_kind && ch != '\n' {
1497                end += ch.len_utf8();
1498            } else {
1499                break;
1500            }
1501        }
1502
1503        (start..end, word_kind)
1504    }
1505
1506    pub fn as_singleton(&self) -> Option<(&ExcerptId, usize, &BufferSnapshot)> {
1507        if self.singleton {
1508            self.excerpts
1509                .iter()
1510                .next()
1511                .map(|e| (&e.id, e.buffer_id, &e.buffer))
1512        } else {
1513            None
1514        }
1515    }
1516
1517    pub fn len(&self) -> usize {
1518        self.excerpts.summary().text.bytes
1519    }
1520
1521    pub fn max_buffer_row(&self) -> u32 {
1522        self.excerpts.summary().max_buffer_row
1523    }
1524
1525    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
1526        if let Some((_, _, buffer)) = self.as_singleton() {
1527            return buffer.clip_offset(offset, bias);
1528        }
1529
1530        let mut cursor = self.excerpts.cursor::<usize>();
1531        cursor.seek(&offset, Bias::Right, &());
1532        let overshoot = if let Some(excerpt) = cursor.item() {
1533            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1534            let buffer_offset = excerpt
1535                .buffer
1536                .clip_offset(excerpt_start + (offset - cursor.start()), bias);
1537            buffer_offset.saturating_sub(excerpt_start)
1538        } else {
1539            0
1540        };
1541        cursor.start() + overshoot
1542    }
1543
1544    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
1545        if let Some((_, _, buffer)) = self.as_singleton() {
1546            return buffer.clip_point(point, bias);
1547        }
1548
1549        let mut cursor = self.excerpts.cursor::<Point>();
1550        cursor.seek(&point, Bias::Right, &());
1551        let overshoot = if let Some(excerpt) = cursor.item() {
1552            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1553            let buffer_point = excerpt
1554                .buffer
1555                .clip_point(excerpt_start + (point - cursor.start()), bias);
1556            buffer_point.saturating_sub(excerpt_start)
1557        } else {
1558            Point::zero()
1559        };
1560        *cursor.start() + overshoot
1561    }
1562
1563    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
1564        if let Some((_, _, buffer)) = self.as_singleton() {
1565            return buffer.clip_point_utf16(point, bias);
1566        }
1567
1568        let mut cursor = self.excerpts.cursor::<PointUtf16>();
1569        cursor.seek(&point, Bias::Right, &());
1570        let overshoot = if let Some(excerpt) = cursor.item() {
1571            let excerpt_start = excerpt
1572                .buffer
1573                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1574            let buffer_point = excerpt
1575                .buffer
1576                .clip_point_utf16(excerpt_start + (point - cursor.start()), bias);
1577            buffer_point.saturating_sub(excerpt_start)
1578        } else {
1579            PointUtf16::zero()
1580        };
1581        *cursor.start() + overshoot
1582    }
1583
1584    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
1585        let range = range.start.to_offset(self)..range.end.to_offset(self);
1586        let mut excerpts = self.excerpts.cursor::<usize>();
1587        excerpts.seek(&range.start, Bias::Right, &());
1588
1589        let mut chunk = &[][..];
1590        let excerpt_bytes = if let Some(excerpt) = excerpts.item() {
1591            let mut excerpt_bytes = excerpt
1592                .bytes_in_range(range.start - excerpts.start()..range.end - excerpts.start());
1593            chunk = excerpt_bytes.next().unwrap_or(&[][..]);
1594            Some(excerpt_bytes)
1595        } else {
1596            None
1597        };
1598
1599        MultiBufferBytes {
1600            range,
1601            excerpts,
1602            excerpt_bytes,
1603            chunk,
1604        }
1605    }
1606
1607    pub fn buffer_rows<'a>(&'a self, start_row: u32) -> MultiBufferRows<'a> {
1608        let mut result = MultiBufferRows {
1609            buffer_row_range: 0..0,
1610            excerpts: self.excerpts.cursor(),
1611        };
1612        result.seek(start_row);
1613        result
1614    }
1615
1616    pub fn chunks<'a, T: ToOffset>(
1617        &'a self,
1618        range: Range<T>,
1619        language_aware: bool,
1620    ) -> MultiBufferChunks<'a> {
1621        let range = range.start.to_offset(self)..range.end.to_offset(self);
1622        let mut chunks = MultiBufferChunks {
1623            range: range.clone(),
1624            excerpts: self.excerpts.cursor(),
1625            excerpt_chunks: None,
1626            language_aware,
1627        };
1628        chunks.seek(range.start);
1629        chunks
1630    }
1631
1632    pub fn offset_to_point(&self, offset: usize) -> Point {
1633        if let Some((_, _, buffer)) = self.as_singleton() {
1634            return buffer.offset_to_point(offset);
1635        }
1636
1637        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
1638        cursor.seek(&offset, Bias::Right, &());
1639        if let Some(excerpt) = cursor.item() {
1640            let (start_offset, start_point) = cursor.start();
1641            let overshoot = offset - start_offset;
1642            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1643            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1644            let buffer_point = excerpt
1645                .buffer
1646                .offset_to_point(excerpt_start_offset + overshoot);
1647            *start_point + (buffer_point - excerpt_start_point)
1648        } else {
1649            self.excerpts.summary().text.lines
1650        }
1651    }
1652
1653    pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
1654        if let Some((_, _, buffer)) = self.as_singleton() {
1655            return buffer.offset_to_point_utf16(offset);
1656        }
1657
1658        let mut cursor = self.excerpts.cursor::<(usize, PointUtf16)>();
1659        cursor.seek(&offset, Bias::Right, &());
1660        if let Some(excerpt) = cursor.item() {
1661            let (start_offset, start_point) = cursor.start();
1662            let overshoot = offset - start_offset;
1663            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1664            let excerpt_start_point = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1665            let buffer_point = excerpt
1666                .buffer
1667                .offset_to_point_utf16(excerpt_start_offset + overshoot);
1668            *start_point + (buffer_point - excerpt_start_point)
1669        } else {
1670            self.excerpts.summary().text.lines_utf16
1671        }
1672    }
1673
1674    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
1675        if let Some((_, _, buffer)) = self.as_singleton() {
1676            return buffer.point_to_point_utf16(point);
1677        }
1678
1679        let mut cursor = self.excerpts.cursor::<(Point, PointUtf16)>();
1680        cursor.seek(&point, Bias::Right, &());
1681        if let Some(excerpt) = cursor.item() {
1682            let (start_offset, start_point) = cursor.start();
1683            let overshoot = point - start_offset;
1684            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1685            let excerpt_start_point_utf16 = excerpt.range.start.to_point_utf16(&excerpt.buffer);
1686            let buffer_point = excerpt
1687                .buffer
1688                .point_to_point_utf16(excerpt_start_point + overshoot);
1689            *start_point + (buffer_point - excerpt_start_point_utf16)
1690        } else {
1691            self.excerpts.summary().text.lines_utf16
1692        }
1693    }
1694
1695    pub fn point_to_offset(&self, point: Point) -> usize {
1696        if let Some((_, _, buffer)) = self.as_singleton() {
1697            return buffer.point_to_offset(point);
1698        }
1699
1700        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
1701        cursor.seek(&point, Bias::Right, &());
1702        if let Some(excerpt) = cursor.item() {
1703            let (start_point, start_offset) = cursor.start();
1704            let overshoot = point - start_point;
1705            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1706            let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
1707            let buffer_offset = excerpt
1708                .buffer
1709                .point_to_offset(excerpt_start_point + overshoot);
1710            *start_offset + buffer_offset - excerpt_start_offset
1711        } else {
1712            self.excerpts.summary().text.bytes
1713        }
1714    }
1715
1716    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
1717        if let Some((_, _, buffer)) = self.as_singleton() {
1718            return buffer.point_utf16_to_offset(point);
1719        }
1720
1721        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
1722        cursor.seek(&point, Bias::Right, &());
1723        if let Some(excerpt) = cursor.item() {
1724            let (start_point, start_offset) = cursor.start();
1725            let overshoot = point - start_point;
1726            let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
1727            let excerpt_start_point = excerpt
1728                .buffer
1729                .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
1730            let buffer_offset = excerpt
1731                .buffer
1732                .point_utf16_to_offset(excerpt_start_point + overshoot);
1733            *start_offset + (buffer_offset - excerpt_start_offset)
1734        } else {
1735            self.excerpts.summary().text.bytes
1736        }
1737    }
1738
1739    pub fn indent_column_for_line(&self, row: u32) -> u32 {
1740        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
1741            buffer
1742                .indent_column_for_line(range.start.row)
1743                .min(range.end.column)
1744                .saturating_sub(range.start.column)
1745        } else {
1746            0
1747        }
1748    }
1749
1750    pub fn line_len(&self, row: u32) -> u32 {
1751        if let Some((_, range)) = self.buffer_line_for_row(row) {
1752            range.end.column - range.start.column
1753        } else {
1754            0
1755        }
1756    }
1757
1758    pub fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
1759        let mut cursor = self.excerpts.cursor::<Point>();
1760        cursor.seek(&Point::new(row, 0), Bias::Right, &());
1761        if let Some(excerpt) = cursor.item() {
1762            let overshoot = row - cursor.start().row;
1763            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
1764            let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
1765            let buffer_row = excerpt_start.row + overshoot;
1766            let line_start = Point::new(buffer_row, 0);
1767            let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
1768            return Some((
1769                &excerpt.buffer,
1770                line_start.max(excerpt_start)..line_end.min(excerpt_end),
1771            ));
1772        }
1773        None
1774    }
1775
1776    pub fn max_point(&self) -> Point {
1777        self.text_summary().lines
1778    }
1779
1780    pub fn text_summary(&self) -> TextSummary {
1781        self.excerpts.summary().text.clone()
1782    }
1783
1784    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
1785    where
1786        D: TextDimension,
1787        O: ToOffset,
1788    {
1789        let mut summary = D::default();
1790        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
1791        let mut cursor = self.excerpts.cursor::<usize>();
1792        cursor.seek(&range.start, Bias::Right, &());
1793        if let Some(excerpt) = cursor.item() {
1794            let mut end_before_newline = cursor.end(&());
1795            if excerpt.has_trailing_newline {
1796                end_before_newline -= 1;
1797            }
1798
1799            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1800            let start_in_excerpt = excerpt_start + (range.start - cursor.start());
1801            let end_in_excerpt =
1802                excerpt_start + (cmp::min(end_before_newline, range.end) - cursor.start());
1803            summary.add_assign(
1804                &excerpt
1805                    .buffer
1806                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
1807            );
1808
1809            if range.end > end_before_newline {
1810                summary.add_assign(&D::from_text_summary(&TextSummary {
1811                    bytes: 1,
1812                    lines: Point::new(1 as u32, 0),
1813                    lines_utf16: PointUtf16::new(1 as u32, 0),
1814                    first_line_chars: 0,
1815                    last_line_chars: 0,
1816                    longest_row: 0,
1817                    longest_row_chars: 0,
1818                }));
1819            }
1820
1821            cursor.next(&());
1822        }
1823
1824        if range.end > *cursor.start() {
1825            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
1826                &range.end,
1827                Bias::Right,
1828                &(),
1829            )));
1830            if let Some(excerpt) = cursor.item() {
1831                range.end = cmp::max(*cursor.start(), range.end);
1832
1833                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
1834                let end_in_excerpt = excerpt_start + (range.end - cursor.start());
1835                summary.add_assign(
1836                    &excerpt
1837                        .buffer
1838                        .text_summary_for_range(excerpt_start..end_in_excerpt),
1839                );
1840            }
1841        }
1842
1843        summary
1844    }
1845
1846    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
1847    where
1848        D: TextDimension + Ord + Sub<D, Output = D>,
1849    {
1850        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1851        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
1852        if cursor.item().is_none() {
1853            cursor.next(&());
1854        }
1855
1856        let mut position = D::from_text_summary(&cursor.start().text);
1857        if let Some(excerpt) = cursor.item() {
1858            if excerpt.id == anchor.excerpt_id {
1859                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1860                let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1861                let buffer_position = cmp::min(
1862                    excerpt_buffer_end,
1863                    anchor.text_anchor.summary::<D>(&excerpt.buffer),
1864                );
1865                if buffer_position > excerpt_buffer_start {
1866                    position.add_assign(&(buffer_position - excerpt_buffer_start));
1867                }
1868            }
1869        }
1870        position
1871    }
1872
1873    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
1874    where
1875        D: TextDimension + Ord + Sub<D, Output = D>,
1876        I: 'a + IntoIterator<Item = &'a Anchor>,
1877    {
1878        if let Some((_, _, buffer)) = self.as_singleton() {
1879            return buffer
1880                .summaries_for_anchors(anchors.into_iter().map(|a| &a.text_anchor))
1881                .collect();
1882        }
1883
1884        let mut anchors = anchors.into_iter().peekable();
1885        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
1886        let mut summaries = Vec::new();
1887        while let Some(anchor) = anchors.peek() {
1888            let excerpt_id = &anchor.excerpt_id;
1889            let excerpt_anchors = iter::from_fn(|| {
1890                let anchor = anchors.peek()?;
1891                if anchor.excerpt_id == *excerpt_id {
1892                    Some(&anchors.next().unwrap().text_anchor)
1893                } else {
1894                    None
1895                }
1896            });
1897
1898            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
1899            if cursor.item().is_none() {
1900                cursor.next(&());
1901            }
1902
1903            let position = D::from_text_summary(&cursor.start().text);
1904            if let Some(excerpt) = cursor.item() {
1905                if excerpt.id == *excerpt_id {
1906                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
1907                    let excerpt_buffer_end = excerpt.range.end.summary::<D>(&excerpt.buffer);
1908                    summaries.extend(
1909                        excerpt
1910                            .buffer
1911                            .summaries_for_anchors::<D, _>(excerpt_anchors)
1912                            .map(move |summary| {
1913                                let summary = cmp::min(excerpt_buffer_end.clone(), summary);
1914                                let mut position = position.clone();
1915                                let excerpt_buffer_start = excerpt_buffer_start.clone();
1916                                if summary > excerpt_buffer_start {
1917                                    position.add_assign(&(summary - excerpt_buffer_start));
1918                                }
1919                                position
1920                            }),
1921                    );
1922                    continue;
1923                }
1924            }
1925
1926            summaries.extend(excerpt_anchors.map(|_| position.clone()));
1927        }
1928
1929        summaries
1930    }
1931
1932    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
1933    where
1934        I: 'a + IntoIterator<Item = &'a Anchor>,
1935    {
1936        let mut anchors = anchors.into_iter().enumerate().peekable();
1937        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1938        let mut result = Vec::new();
1939        while let Some((_, anchor)) = anchors.peek() {
1940            let old_excerpt_id = &anchor.excerpt_id;
1941
1942            // Find the location where this anchor's excerpt should be.
1943            cursor.seek_forward(&Some(old_excerpt_id), Bias::Left, &());
1944            if cursor.item().is_none() {
1945                cursor.next(&());
1946            }
1947
1948            let next_excerpt = cursor.item();
1949            let prev_excerpt = cursor.prev_item();
1950
1951            // Process all of the anchors for this excerpt.
1952            while let Some((_, anchor)) = anchors.peek() {
1953                if anchor.excerpt_id != *old_excerpt_id {
1954                    break;
1955                }
1956                let mut kept_position = false;
1957                let (anchor_ix, anchor) = anchors.next().unwrap();
1958                let mut anchor = anchor.clone();
1959
1960                // Leave min and max anchors unchanged.
1961                if *old_excerpt_id == ExcerptId::max() || *old_excerpt_id == ExcerptId::min() {
1962                    kept_position = true;
1963                }
1964                // If the old excerpt still exists at this location, then leave
1965                // the anchor unchanged.
1966                else if next_excerpt.map_or(false, |excerpt| {
1967                    excerpt.id == *old_excerpt_id && excerpt.contains(&anchor)
1968                }) {
1969                    kept_position = true;
1970                }
1971                // If the old excerpt no longer exists at this location, then attempt to
1972                // find an equivalent position for this anchor in an adjacent excerpt.
1973                else {
1974                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
1975                        if excerpt.contains(&anchor) {
1976                            anchor.excerpt_id = excerpt.id.clone();
1977                            kept_position = true;
1978                            break;
1979                        }
1980                    }
1981                }
1982                // If there's no adjacent excerpt that contains the anchor's position,
1983                // then report that the anchor has lost its position.
1984                if !kept_position {
1985                    anchor = if let Some(excerpt) = next_excerpt {
1986                        let mut text_anchor = excerpt
1987                            .range
1988                            .start
1989                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
1990                        if text_anchor.cmp(&excerpt.range.end, &excerpt.buffer).is_gt() {
1991                            text_anchor = excerpt.range.end.clone();
1992                        }
1993                        Anchor {
1994                            buffer_id: Some(excerpt.buffer_id),
1995                            excerpt_id: excerpt.id.clone(),
1996                            text_anchor,
1997                        }
1998                    } else if let Some(excerpt) = prev_excerpt {
1999                        let mut text_anchor = excerpt
2000                            .range
2001                            .end
2002                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
2003                        if text_anchor
2004                            .cmp(&excerpt.range.start, &excerpt.buffer)
2005                            .is_lt()
2006                        {
2007                            text_anchor = excerpt.range.start.clone();
2008                        }
2009                        Anchor {
2010                            buffer_id: Some(excerpt.buffer_id),
2011                            excerpt_id: excerpt.id.clone(),
2012                            text_anchor,
2013                        }
2014                    } else if anchor.text_anchor.bias == Bias::Left {
2015                        Anchor::min()
2016                    } else {
2017                        Anchor::max()
2018                    };
2019                }
2020
2021                result.push((anchor_ix, anchor, kept_position));
2022            }
2023        }
2024        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
2025        result
2026    }
2027
2028    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
2029        self.anchor_at(position, Bias::Left)
2030    }
2031
2032    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
2033        self.anchor_at(position, Bias::Right)
2034    }
2035
2036    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
2037        let offset = position.to_offset(self);
2038        if let Some((excerpt_id, buffer_id, buffer)) = self.as_singleton() {
2039            return Anchor {
2040                buffer_id: Some(buffer_id),
2041                excerpt_id: excerpt_id.clone(),
2042                text_anchor: buffer.anchor_at(offset, bias),
2043            };
2044        }
2045
2046        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
2047        cursor.seek(&offset, Bias::Right, &());
2048        if cursor.item().is_none() && offset == cursor.start().0 && bias == Bias::Left {
2049            cursor.prev(&());
2050        }
2051        if let Some(excerpt) = cursor.item() {
2052            let mut overshoot = offset.saturating_sub(cursor.start().0);
2053            if excerpt.has_trailing_newline && offset == cursor.end(&()).0 {
2054                overshoot -= 1;
2055                bias = Bias::Right;
2056            }
2057
2058            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
2059            let text_anchor =
2060                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
2061            Anchor {
2062                buffer_id: Some(excerpt.buffer_id),
2063                excerpt_id: excerpt.id.clone(),
2064                text_anchor,
2065            }
2066        } else if offset == 0 && bias == Bias::Left {
2067            Anchor::min()
2068        } else {
2069            Anchor::max()
2070        }
2071    }
2072
2073    pub fn anchor_in_excerpt(&self, excerpt_id: ExcerptId, text_anchor: text::Anchor) -> Anchor {
2074        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2075        cursor.seek(&Some(&excerpt_id), Bias::Left, &());
2076        if let Some(excerpt) = cursor.item() {
2077            if excerpt.id == excerpt_id {
2078                let text_anchor = excerpt.clip_anchor(text_anchor);
2079                drop(cursor);
2080                return Anchor {
2081                    buffer_id: Some(excerpt.buffer_id),
2082                    excerpt_id,
2083                    text_anchor,
2084                };
2085            }
2086        }
2087        panic!("excerpt not found");
2088    }
2089
2090    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
2091        if anchor.excerpt_id == ExcerptId::min() || anchor.excerpt_id == ExcerptId::max() {
2092            true
2093        } else if let Some(excerpt) = self.excerpt(&anchor.excerpt_id) {
2094            excerpt.buffer.can_resolve(&anchor.text_anchor)
2095        } else {
2096            false
2097        }
2098    }
2099
2100    pub fn excerpt_boundaries_in_range<'a, R, T>(
2101        &'a self,
2102        range: R,
2103    ) -> impl Iterator<Item = ExcerptBoundary> + 'a
2104    where
2105        R: RangeBounds<T>,
2106        T: ToOffset,
2107    {
2108        let start_offset;
2109        let start = match range.start_bound() {
2110            Bound::Included(start) => {
2111                start_offset = start.to_offset(self);
2112                Bound::Included(start_offset)
2113            }
2114            Bound::Excluded(start) => {
2115                start_offset = start.to_offset(self);
2116                Bound::Excluded(start_offset)
2117            }
2118            Bound::Unbounded => {
2119                start_offset = 0;
2120                Bound::Unbounded
2121            }
2122        };
2123        let end = match range.end_bound() {
2124            Bound::Included(end) => Bound::Included(end.to_offset(self)),
2125            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
2126            Bound::Unbounded => Bound::Unbounded,
2127        };
2128        let bounds = (start, end);
2129
2130        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
2131        cursor.seek(&start_offset, Bias::Right, &());
2132        if cursor.item().is_none() {
2133            cursor.prev(&());
2134        }
2135        if !bounds.contains(&cursor.start().0) {
2136            cursor.next(&());
2137        }
2138
2139        let mut prev_buffer_id = cursor.prev_item().map(|excerpt| excerpt.buffer_id);
2140        std::iter::from_fn(move || {
2141            if self.singleton {
2142                None
2143            } else if bounds.contains(&cursor.start().0) {
2144                let excerpt = cursor.item()?;
2145                let starts_new_buffer = Some(excerpt.buffer_id) != prev_buffer_id;
2146                let boundary = ExcerptBoundary {
2147                    id: excerpt.id.clone(),
2148                    row: cursor.start().1.row,
2149                    buffer: excerpt.buffer.clone(),
2150                    range: excerpt.range.clone(),
2151                    starts_new_buffer,
2152                };
2153
2154                prev_buffer_id = Some(excerpt.buffer_id);
2155                cursor.next(&());
2156                Some(boundary)
2157            } else {
2158                None
2159            }
2160        })
2161    }
2162
2163    pub fn parse_count(&self) -> usize {
2164        self.parse_count
2165    }
2166
2167    pub fn enclosing_bracket_ranges<T: ToOffset>(
2168        &self,
2169        range: Range<T>,
2170    ) -> Option<(Range<usize>, Range<usize>)> {
2171        let range = range.start.to_offset(self)..range.end.to_offset(self);
2172
2173        let mut cursor = self.excerpts.cursor::<usize>();
2174        cursor.seek(&range.start, Bias::Right, &());
2175        let start_excerpt = cursor.item();
2176
2177        cursor.seek(&range.end, Bias::Right, &());
2178        let end_excerpt = cursor.item();
2179
2180        start_excerpt
2181            .zip(end_excerpt)
2182            .and_then(|(start_excerpt, end_excerpt)| {
2183                if start_excerpt.id != end_excerpt.id {
2184                    return None;
2185                }
2186
2187                let excerpt_buffer_start =
2188                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2189                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2190
2191                let start_in_buffer =
2192                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2193                let end_in_buffer =
2194                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2195                let (mut start_bracket_range, mut end_bracket_range) = start_excerpt
2196                    .buffer
2197                    .enclosing_bracket_ranges(start_in_buffer..end_in_buffer)?;
2198
2199                if start_bracket_range.start >= excerpt_buffer_start
2200                    && end_bracket_range.end < excerpt_buffer_end
2201                {
2202                    start_bracket_range.start =
2203                        cursor.start() + (start_bracket_range.start - excerpt_buffer_start);
2204                    start_bracket_range.end =
2205                        cursor.start() + (start_bracket_range.end - excerpt_buffer_start);
2206                    end_bracket_range.start =
2207                        cursor.start() + (end_bracket_range.start - excerpt_buffer_start);
2208                    end_bracket_range.end =
2209                        cursor.start() + (end_bracket_range.end - excerpt_buffer_start);
2210                    Some((start_bracket_range, end_bracket_range))
2211                } else {
2212                    None
2213                }
2214            })
2215    }
2216
2217    pub fn diagnostics_update_count(&self) -> usize {
2218        self.diagnostics_update_count
2219    }
2220
2221    pub fn trailing_excerpt_update_count(&self) -> usize {
2222        self.trailing_excerpt_update_count
2223    }
2224
2225    pub fn language(&self) -> Option<&Arc<Language>> {
2226        self.excerpts
2227            .iter()
2228            .next()
2229            .and_then(|excerpt| excerpt.buffer.language())
2230    }
2231
2232    pub fn is_dirty(&self) -> bool {
2233        self.is_dirty
2234    }
2235
2236    pub fn has_conflict(&self) -> bool {
2237        self.has_conflict
2238    }
2239
2240    pub fn diagnostic_group<'a, O>(
2241        &'a self,
2242        group_id: usize,
2243    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2244    where
2245        O: text::FromAnchor + 'a,
2246    {
2247        self.as_singleton()
2248            .into_iter()
2249            .flat_map(move |(_, _, buffer)| buffer.diagnostic_group(group_id))
2250    }
2251
2252    pub fn diagnostics_in_range<'a, T, O>(
2253        &'a self,
2254        range: Range<T>,
2255        reversed: bool,
2256    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
2257    where
2258        T: 'a + ToOffset,
2259        O: 'a + text::FromAnchor,
2260    {
2261        self.as_singleton()
2262            .into_iter()
2263            .flat_map(move |(_, _, buffer)| {
2264                buffer.diagnostics_in_range(
2265                    range.start.to_offset(self)..range.end.to_offset(self),
2266                    reversed,
2267                )
2268            })
2269    }
2270
2271    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
2272        let range = range.start.to_offset(self)..range.end.to_offset(self);
2273
2274        let mut cursor = self.excerpts.cursor::<usize>();
2275        cursor.seek(&range.start, Bias::Right, &());
2276        let start_excerpt = cursor.item();
2277
2278        cursor.seek(&range.end, Bias::Right, &());
2279        let end_excerpt = cursor.item();
2280
2281        start_excerpt
2282            .zip(end_excerpt)
2283            .and_then(|(start_excerpt, end_excerpt)| {
2284                if start_excerpt.id != end_excerpt.id {
2285                    return None;
2286                }
2287
2288                let excerpt_buffer_start =
2289                    start_excerpt.range.start.to_offset(&start_excerpt.buffer);
2290                let excerpt_buffer_end = excerpt_buffer_start + start_excerpt.text_summary.bytes;
2291
2292                let start_in_buffer =
2293                    excerpt_buffer_start + range.start.saturating_sub(*cursor.start());
2294                let end_in_buffer =
2295                    excerpt_buffer_start + range.end.saturating_sub(*cursor.start());
2296                let mut ancestor_buffer_range = start_excerpt
2297                    .buffer
2298                    .range_for_syntax_ancestor(start_in_buffer..end_in_buffer)?;
2299                ancestor_buffer_range.start =
2300                    cmp::max(ancestor_buffer_range.start, excerpt_buffer_start);
2301                ancestor_buffer_range.end = cmp::min(ancestor_buffer_range.end, excerpt_buffer_end);
2302
2303                let start = cursor.start() + (ancestor_buffer_range.start - excerpt_buffer_start);
2304                let end = cursor.start() + (ancestor_buffer_range.end - excerpt_buffer_start);
2305                Some(start..end)
2306            })
2307    }
2308
2309    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
2310        let (excerpt_id, _, buffer) = self.as_singleton()?;
2311        let outline = buffer.outline(theme)?;
2312        Some(Outline::new(
2313            outline
2314                .items
2315                .into_iter()
2316                .map(|item| OutlineItem {
2317                    depth: item.depth,
2318                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
2319                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
2320                    text: item.text,
2321                    highlight_ranges: item.highlight_ranges,
2322                    name_ranges: item.name_ranges,
2323                })
2324                .collect(),
2325        ))
2326    }
2327
2328    pub fn symbols_containing<T: ToOffset>(
2329        &self,
2330        offset: T,
2331        theme: Option<&SyntaxTheme>,
2332    ) -> Option<(usize, Vec<OutlineItem<Anchor>>)> {
2333        let anchor = self.anchor_before(offset);
2334        let excerpt_id = anchor.excerpt_id();
2335        let excerpt = self.excerpt(excerpt_id)?;
2336        Some((
2337            excerpt.buffer_id,
2338            excerpt
2339                .buffer
2340                .symbols_containing(anchor.text_anchor, theme)
2341                .into_iter()
2342                .flatten()
2343                .map(|item| OutlineItem {
2344                    depth: item.depth,
2345                    range: self.anchor_in_excerpt(excerpt_id.clone(), item.range.start)
2346                        ..self.anchor_in_excerpt(excerpt_id.clone(), item.range.end),
2347                    text: item.text,
2348                    highlight_ranges: item.highlight_ranges,
2349                    name_ranges: item.name_ranges,
2350                })
2351                .collect(),
2352        ))
2353    }
2354
2355    fn excerpt<'a>(&'a self, excerpt_id: &'a ExcerptId) -> Option<&'a Excerpt> {
2356        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2357        cursor.seek(&Some(excerpt_id), Bias::Left, &());
2358        if let Some(excerpt) = cursor.item() {
2359            if excerpt.id == *excerpt_id {
2360                return Some(excerpt);
2361            }
2362        }
2363        None
2364    }
2365
2366    pub fn remote_selections_in_range<'a>(
2367        &'a self,
2368        range: &'a Range<Anchor>,
2369    ) -> impl 'a + Iterator<Item = (ReplicaId, Selection<Anchor>)> {
2370        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
2371        cursor.seek(&Some(&range.start.excerpt_id), Bias::Left, &());
2372        cursor
2373            .take_while(move |excerpt| excerpt.id <= range.end.excerpt_id)
2374            .flat_map(move |excerpt| {
2375                let mut query_range = excerpt.range.start.clone()..excerpt.range.end.clone();
2376                if excerpt.id == range.start.excerpt_id {
2377                    query_range.start = range.start.text_anchor.clone();
2378                }
2379                if excerpt.id == range.end.excerpt_id {
2380                    query_range.end = range.end.text_anchor.clone();
2381                }
2382
2383                excerpt
2384                    .buffer
2385                    .remote_selections_in_range(query_range)
2386                    .flat_map(move |(replica_id, selections)| {
2387                        selections.map(move |selection| {
2388                            let mut start = Anchor {
2389                                buffer_id: Some(excerpt.buffer_id),
2390                                excerpt_id: excerpt.id.clone(),
2391                                text_anchor: selection.start.clone(),
2392                            };
2393                            let mut end = Anchor {
2394                                buffer_id: Some(excerpt.buffer_id),
2395                                excerpt_id: excerpt.id.clone(),
2396                                text_anchor: selection.end.clone(),
2397                            };
2398                            if range.start.cmp(&start, self).is_gt() {
2399                                start = range.start.clone();
2400                            }
2401                            if range.end.cmp(&end, self).is_lt() {
2402                                end = range.end.clone();
2403                            }
2404
2405                            (
2406                                replica_id,
2407                                Selection {
2408                                    id: selection.id,
2409                                    start,
2410                                    end,
2411                                    reversed: selection.reversed,
2412                                    goal: selection.goal,
2413                                },
2414                            )
2415                        })
2416                    })
2417            })
2418    }
2419}
2420
2421#[cfg(any(test, feature = "test-support"))]
2422impl MultiBufferSnapshot {
2423    pub fn random_byte_range(&self, start_offset: usize, rng: &mut impl rand::Rng) -> Range<usize> {
2424        let end = self.clip_offset(rng.gen_range(start_offset..=self.len()), Bias::Right);
2425        let start = self.clip_offset(rng.gen_range(start_offset..=end), Bias::Right);
2426        start..end
2427    }
2428}
2429
2430impl History {
2431    fn start_transaction(&mut self, now: Instant) -> Option<TransactionId> {
2432        self.transaction_depth += 1;
2433        if self.transaction_depth == 1 {
2434            let id = self.next_transaction_id.tick();
2435            self.undo_stack.push(Transaction {
2436                id,
2437                buffer_transactions: Default::default(),
2438                first_edit_at: now,
2439                last_edit_at: now,
2440                suppress_grouping: false,
2441            });
2442            Some(id)
2443        } else {
2444            None
2445        }
2446    }
2447
2448    fn end_transaction(
2449        &mut self,
2450        now: Instant,
2451        buffer_transactions: HashMap<usize, TransactionId>,
2452    ) -> bool {
2453        assert_ne!(self.transaction_depth, 0);
2454        self.transaction_depth -= 1;
2455        if self.transaction_depth == 0 {
2456            if buffer_transactions.is_empty() {
2457                self.undo_stack.pop();
2458                false
2459            } else {
2460                let transaction = self.undo_stack.last_mut().unwrap();
2461                transaction.last_edit_at = now;
2462                for (buffer_id, transaction_id) in buffer_transactions {
2463                    transaction
2464                        .buffer_transactions
2465                        .entry(buffer_id)
2466                        .or_insert(transaction_id);
2467                }
2468                true
2469            }
2470        } else {
2471            false
2472        }
2473    }
2474
2475    fn push_transaction<'a, T>(&mut self, buffer_transactions: T, now: Instant)
2476    where
2477        T: IntoIterator<Item = (&'a ModelHandle<Buffer>, &'a language::Transaction)>,
2478    {
2479        assert_eq!(self.transaction_depth, 0);
2480        let transaction = Transaction {
2481            id: self.next_transaction_id.tick(),
2482            buffer_transactions: buffer_transactions
2483                .into_iter()
2484                .map(|(buffer, transaction)| (buffer.id(), transaction.id))
2485                .collect(),
2486            first_edit_at: now,
2487            last_edit_at: now,
2488            suppress_grouping: false,
2489        };
2490        if !transaction.buffer_transactions.is_empty() {
2491            self.undo_stack.push(transaction);
2492        }
2493    }
2494
2495    fn finalize_last_transaction(&mut self) {
2496        if let Some(transaction) = self.undo_stack.last_mut() {
2497            transaction.suppress_grouping = true;
2498        }
2499    }
2500
2501    fn pop_undo(&mut self) -> Option<&mut Transaction> {
2502        assert_eq!(self.transaction_depth, 0);
2503        if let Some(transaction) = self.undo_stack.pop() {
2504            self.redo_stack.push(transaction);
2505            self.redo_stack.last_mut()
2506        } else {
2507            None
2508        }
2509    }
2510
2511    fn pop_redo(&mut self) -> Option<&mut Transaction> {
2512        assert_eq!(self.transaction_depth, 0);
2513        if let Some(transaction) = self.redo_stack.pop() {
2514            self.undo_stack.push(transaction);
2515            self.undo_stack.last_mut()
2516        } else {
2517            None
2518        }
2519    }
2520
2521    fn group(&mut self) -> Option<TransactionId> {
2522        let mut new_len = self.undo_stack.len();
2523        let mut transactions = self.undo_stack.iter_mut();
2524
2525        if let Some(mut transaction) = transactions.next_back() {
2526            while let Some(prev_transaction) = transactions.next_back() {
2527                if !prev_transaction.suppress_grouping
2528                    && transaction.first_edit_at - prev_transaction.last_edit_at
2529                        <= self.group_interval
2530                {
2531                    transaction = prev_transaction;
2532                    new_len -= 1;
2533                } else {
2534                    break;
2535                }
2536            }
2537        }
2538
2539        let (transactions_to_keep, transactions_to_merge) = self.undo_stack.split_at_mut(new_len);
2540        if let Some(last_transaction) = transactions_to_keep.last_mut() {
2541            if let Some(transaction) = transactions_to_merge.last() {
2542                last_transaction.last_edit_at = transaction.last_edit_at;
2543            }
2544            for to_merge in transactions_to_merge {
2545                for (buffer_id, transaction_id) in &to_merge.buffer_transactions {
2546                    last_transaction
2547                        .buffer_transactions
2548                        .entry(*buffer_id)
2549                        .or_insert(*transaction_id);
2550                }
2551            }
2552        }
2553
2554        self.undo_stack.truncate(new_len);
2555        self.undo_stack.last().map(|t| t.id)
2556    }
2557}
2558
2559impl Excerpt {
2560    fn new(
2561        id: ExcerptId,
2562        buffer_id: usize,
2563        buffer: BufferSnapshot,
2564        range: Range<text::Anchor>,
2565        has_trailing_newline: bool,
2566    ) -> Self {
2567        Excerpt {
2568            id,
2569            max_buffer_row: range.end.to_point(&buffer).row,
2570            text_summary: buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer)),
2571            buffer_id,
2572            buffer,
2573            range,
2574            has_trailing_newline,
2575        }
2576    }
2577
2578    fn chunks_in_range<'a>(
2579        &'a self,
2580        range: Range<usize>,
2581        language_aware: bool,
2582    ) -> ExcerptChunks<'a> {
2583        let content_start = self.range.start.to_offset(&self.buffer);
2584        let chunks_start = content_start + range.start;
2585        let chunks_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2586
2587        let footer_height = if self.has_trailing_newline
2588            && range.start <= self.text_summary.bytes
2589            && range.end > self.text_summary.bytes
2590        {
2591            1
2592        } else {
2593            0
2594        };
2595
2596        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
2597
2598        ExcerptChunks {
2599            content_chunks,
2600            footer_height,
2601        }
2602    }
2603
2604    fn bytes_in_range(&self, range: Range<usize>) -> ExcerptBytes {
2605        let content_start = self.range.start.to_offset(&self.buffer);
2606        let bytes_start = content_start + range.start;
2607        let bytes_end = content_start + cmp::min(range.end, self.text_summary.bytes);
2608        let footer_height = if self.has_trailing_newline
2609            && range.start <= self.text_summary.bytes
2610            && range.end > self.text_summary.bytes
2611        {
2612            1
2613        } else {
2614            0
2615        };
2616        let content_bytes = self.buffer.bytes_in_range(bytes_start..bytes_end);
2617
2618        ExcerptBytes {
2619            content_bytes,
2620            footer_height,
2621        }
2622    }
2623
2624    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
2625        if text_anchor.cmp(&self.range.start, &self.buffer).is_lt() {
2626            self.range.start.clone()
2627        } else if text_anchor.cmp(&self.range.end, &self.buffer).is_gt() {
2628            self.range.end.clone()
2629        } else {
2630            text_anchor
2631        }
2632    }
2633
2634    fn contains(&self, anchor: &Anchor) -> bool {
2635        Some(self.buffer_id) == anchor.buffer_id
2636            && self
2637                .range
2638                .start
2639                .cmp(&anchor.text_anchor, &self.buffer)
2640                .is_le()
2641            && self
2642                .range
2643                .end
2644                .cmp(&anchor.text_anchor, &self.buffer)
2645                .is_ge()
2646    }
2647}
2648
2649impl fmt::Debug for Excerpt {
2650    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2651        f.debug_struct("Excerpt")
2652            .field("id", &self.id)
2653            .field("buffer_id", &self.buffer_id)
2654            .field("range", &self.range)
2655            .field("text_summary", &self.text_summary)
2656            .field("has_trailing_newline", &self.has_trailing_newline)
2657            .finish()
2658    }
2659}
2660
2661impl sum_tree::Item for Excerpt {
2662    type Summary = ExcerptSummary;
2663
2664    fn summary(&self) -> Self::Summary {
2665        let mut text = self.text_summary.clone();
2666        if self.has_trailing_newline {
2667            text += TextSummary::from("\n");
2668        }
2669        ExcerptSummary {
2670            excerpt_id: self.id.clone(),
2671            max_buffer_row: self.max_buffer_row,
2672            text,
2673        }
2674    }
2675}
2676
2677impl sum_tree::Summary for ExcerptSummary {
2678    type Context = ();
2679
2680    fn add_summary(&mut self, summary: &Self, _: &()) {
2681        debug_assert!(summary.excerpt_id > self.excerpt_id);
2682        self.excerpt_id = summary.excerpt_id.clone();
2683        self.text.add_summary(&summary.text, &());
2684        self.max_buffer_row = cmp::max(self.max_buffer_row, summary.max_buffer_row);
2685    }
2686}
2687
2688impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
2689    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2690        *self += &summary.text;
2691    }
2692}
2693
2694impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
2695    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2696        *self += summary.text.bytes;
2697    }
2698}
2699
2700impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
2701    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2702        Ord::cmp(self, &cursor_location.text.bytes)
2703    }
2704}
2705
2706impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
2707    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
2708        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
2709    }
2710}
2711
2712impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
2713    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2714        *self += summary.text.lines;
2715    }
2716}
2717
2718impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
2719    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2720        *self += summary.text.lines_utf16
2721    }
2722}
2723
2724impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
2725    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
2726        *self = Some(&summary.excerpt_id);
2727    }
2728}
2729
2730impl<'a> MultiBufferRows<'a> {
2731    pub fn seek(&mut self, row: u32) {
2732        self.buffer_row_range = 0..0;
2733
2734        self.excerpts
2735            .seek_forward(&Point::new(row, 0), Bias::Right, &());
2736        if self.excerpts.item().is_none() {
2737            self.excerpts.prev(&());
2738
2739            if self.excerpts.item().is_none() && row == 0 {
2740                self.buffer_row_range = 0..1;
2741                return;
2742            }
2743        }
2744
2745        if let Some(excerpt) = self.excerpts.item() {
2746            let overshoot = row - self.excerpts.start().row;
2747            let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer).row;
2748            self.buffer_row_range.start = excerpt_start + overshoot;
2749            self.buffer_row_range.end = excerpt_start + excerpt.text_summary.lines.row + 1;
2750        }
2751    }
2752}
2753
2754impl<'a> Iterator for MultiBufferRows<'a> {
2755    type Item = Option<u32>;
2756
2757    fn next(&mut self) -> Option<Self::Item> {
2758        loop {
2759            if !self.buffer_row_range.is_empty() {
2760                let row = Some(self.buffer_row_range.start);
2761                self.buffer_row_range.start += 1;
2762                return Some(row);
2763            }
2764            self.excerpts.item()?;
2765            self.excerpts.next(&());
2766            let excerpt = self.excerpts.item()?;
2767            self.buffer_row_range.start = excerpt.range.start.to_point(&excerpt.buffer).row;
2768            self.buffer_row_range.end =
2769                self.buffer_row_range.start + excerpt.text_summary.lines.row + 1;
2770        }
2771    }
2772}
2773
2774impl<'a> MultiBufferChunks<'a> {
2775    pub fn offset(&self) -> usize {
2776        self.range.start
2777    }
2778
2779    pub fn seek(&mut self, offset: usize) {
2780        self.range.start = offset;
2781        self.excerpts.seek(&offset, Bias::Right, &());
2782        if let Some(excerpt) = self.excerpts.item() {
2783            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2784                self.range.start - self.excerpts.start()..self.range.end - self.excerpts.start(),
2785                self.language_aware,
2786            ));
2787        } else {
2788            self.excerpt_chunks = None;
2789        }
2790    }
2791}
2792
2793impl<'a> Iterator for MultiBufferChunks<'a> {
2794    type Item = Chunk<'a>;
2795
2796    fn next(&mut self) -> Option<Self::Item> {
2797        if self.range.is_empty() {
2798            None
2799        } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
2800            self.range.start += chunk.text.len();
2801            Some(chunk)
2802        } else {
2803            self.excerpts.next(&());
2804            let excerpt = self.excerpts.item()?;
2805            self.excerpt_chunks = Some(excerpt.chunks_in_range(
2806                0..self.range.end - self.excerpts.start(),
2807                self.language_aware,
2808            ));
2809            self.next()
2810        }
2811    }
2812}
2813
2814impl<'a> MultiBufferBytes<'a> {
2815    fn consume(&mut self, len: usize) {
2816        self.range.start += len;
2817        self.chunk = &self.chunk[len..];
2818
2819        if !self.range.is_empty() && self.chunk.is_empty() {
2820            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
2821                self.chunk = chunk;
2822            } else {
2823                self.excerpts.next(&());
2824                if let Some(excerpt) = self.excerpts.item() {
2825                    let mut excerpt_bytes =
2826                        excerpt.bytes_in_range(0..self.range.end - self.excerpts.start());
2827                    self.chunk = excerpt_bytes.next().unwrap();
2828                    self.excerpt_bytes = Some(excerpt_bytes);
2829                }
2830            }
2831        }
2832    }
2833}
2834
2835impl<'a> Iterator for MultiBufferBytes<'a> {
2836    type Item = &'a [u8];
2837
2838    fn next(&mut self) -> Option<Self::Item> {
2839        let chunk = self.chunk;
2840        if chunk.is_empty() {
2841            None
2842        } else {
2843            self.consume(chunk.len());
2844            Some(chunk)
2845        }
2846    }
2847}
2848
2849impl<'a> io::Read for MultiBufferBytes<'a> {
2850    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
2851        let len = cmp::min(buf.len(), self.chunk.len());
2852        buf[..len].copy_from_slice(&self.chunk[..len]);
2853        if len > 0 {
2854            self.consume(len);
2855        }
2856        Ok(len)
2857    }
2858}
2859
2860impl<'a> Iterator for ExcerptBytes<'a> {
2861    type Item = &'a [u8];
2862
2863    fn next(&mut self) -> Option<Self::Item> {
2864        if let Some(chunk) = self.content_bytes.next() {
2865            if !chunk.is_empty() {
2866                return Some(chunk);
2867            }
2868        }
2869
2870        if self.footer_height > 0 {
2871            let result = &NEWLINES[..self.footer_height];
2872            self.footer_height = 0;
2873            return Some(result);
2874        }
2875
2876        None
2877    }
2878}
2879
2880impl<'a> Iterator for ExcerptChunks<'a> {
2881    type Item = Chunk<'a>;
2882
2883    fn next(&mut self) -> Option<Self::Item> {
2884        if let Some(chunk) = self.content_chunks.next() {
2885            return Some(chunk);
2886        }
2887
2888        if self.footer_height > 0 {
2889            let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
2890            self.footer_height = 0;
2891            return Some(Chunk {
2892                text,
2893                ..Default::default()
2894            });
2895        }
2896
2897        None
2898    }
2899}
2900
2901impl ToOffset for Point {
2902    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2903        snapshot.point_to_offset(*self)
2904    }
2905}
2906
2907impl ToOffset for PointUtf16 {
2908    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2909        snapshot.point_utf16_to_offset(*self)
2910    }
2911}
2912
2913impl ToOffset for usize {
2914    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
2915        assert!(*self <= snapshot.len(), "offset is out of range");
2916        *self
2917    }
2918}
2919
2920impl ToPoint for usize {
2921    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
2922        snapshot.offset_to_point(*self)
2923    }
2924}
2925
2926impl ToPoint for Point {
2927    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
2928        *self
2929    }
2930}
2931
2932impl ToPointUtf16 for usize {
2933    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2934        snapshot.offset_to_point_utf16(*self)
2935    }
2936}
2937
2938impl ToPointUtf16 for Point {
2939    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
2940        snapshot.point_to_point_utf16(*self)
2941    }
2942}
2943
2944impl ToPointUtf16 for PointUtf16 {
2945    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
2946        *self
2947    }
2948}
2949
2950#[cfg(test)]
2951mod tests {
2952    use super::*;
2953    use gpui::MutableAppContext;
2954    use language::{Buffer, Rope};
2955    use rand::prelude::*;
2956    use std::{env, rc::Rc};
2957    use text::{Point, RandomCharIter};
2958    use util::test::sample_text;
2959
2960    #[gpui::test]
2961    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
2962        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
2963        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
2964
2965        let snapshot = multibuffer.read(cx).snapshot(cx);
2966        assert_eq!(snapshot.text(), buffer.read(cx).text());
2967
2968        assert_eq!(
2969            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2970            (0..buffer.read(cx).row_count())
2971                .map(Some)
2972                .collect::<Vec<_>>()
2973        );
2974
2975        buffer.update(cx, |buffer, cx| buffer.edit(1..3, "XXX\n", cx));
2976        let snapshot = multibuffer.read(cx).snapshot(cx);
2977
2978        assert_eq!(snapshot.text(), buffer.read(cx).text());
2979        assert_eq!(
2980            snapshot.buffer_rows(0).collect::<Vec<_>>(),
2981            (0..buffer.read(cx).row_count())
2982                .map(Some)
2983                .collect::<Vec<_>>()
2984        );
2985    }
2986
2987    #[gpui::test]
2988    fn test_remote_multibuffer(cx: &mut MutableAppContext) {
2989        let host_buffer = cx.add_model(|cx| Buffer::new(0, "a", cx));
2990        let guest_buffer = cx.add_model(|cx| {
2991            let message = host_buffer.read(cx).to_proto();
2992            Buffer::from_proto(1, message, None, cx).unwrap()
2993        });
2994        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(guest_buffer.clone(), cx));
2995        let snapshot = multibuffer.read(cx).snapshot(cx);
2996        assert_eq!(snapshot.text(), "a");
2997
2998        guest_buffer.update(cx, |buffer, cx| buffer.edit(1..1, "b", cx));
2999        let snapshot = multibuffer.read(cx).snapshot(cx);
3000        assert_eq!(snapshot.text(), "ab");
3001
3002        guest_buffer.update(cx, |buffer, cx| buffer.edit(2..2, "c", cx));
3003        let snapshot = multibuffer.read(cx).snapshot(cx);
3004        assert_eq!(snapshot.text(), "abc");
3005    }
3006
3007    #[gpui::test]
3008    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
3009        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
3010        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
3011        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3012
3013        let events = Rc::new(RefCell::new(Vec::<Event>::new()));
3014        multibuffer.update(cx, |_, cx| {
3015            let events = events.clone();
3016            cx.subscribe(&multibuffer, move |_, _, event, _| {
3017                events.borrow_mut().push(event.clone())
3018            })
3019            .detach();
3020        });
3021
3022        let subscription = multibuffer.update(cx, |multibuffer, cx| {
3023            let subscription = multibuffer.subscribe();
3024            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(1, 2)..Point::new(2, 5)], cx);
3025            assert_eq!(
3026                subscription.consume().into_inner(),
3027                [Edit {
3028                    old: 0..0,
3029                    new: 0..10
3030                }]
3031            );
3032
3033            multibuffer.push_excerpts(buffer_1.clone(), [Point::new(3, 3)..Point::new(4, 4)], cx);
3034            multibuffer.push_excerpts(buffer_2.clone(), [Point::new(3, 1)..Point::new(3, 3)], cx);
3035            assert_eq!(
3036                subscription.consume().into_inner(),
3037                [Edit {
3038                    old: 10..10,
3039                    new: 10..22
3040                }]
3041            );
3042
3043            subscription
3044        });
3045
3046        // Adding excerpts emits an edited event.
3047        assert_eq!(
3048            events.borrow().as_slice(),
3049            &[Event::Edited, Event::Edited, Event::Edited]
3050        );
3051
3052        let snapshot = multibuffer.read(cx).snapshot(cx);
3053        assert_eq!(
3054            snapshot.text(),
3055            concat!(
3056                "bbbb\n",  // Preserve newlines
3057                "ccccc\n", //
3058                "ddd\n",   //
3059                "eeee\n",  //
3060                "jj"       //
3061            )
3062        );
3063        assert_eq!(
3064            snapshot.buffer_rows(0).collect::<Vec<_>>(),
3065            [Some(1), Some(2), Some(3), Some(4), Some(3)]
3066        );
3067        assert_eq!(
3068            snapshot.buffer_rows(2).collect::<Vec<_>>(),
3069            [Some(3), Some(4), Some(3)]
3070        );
3071        assert_eq!(snapshot.buffer_rows(4).collect::<Vec<_>>(), [Some(3)]);
3072        assert_eq!(snapshot.buffer_rows(5).collect::<Vec<_>>(), []);
3073
3074        assert_eq!(
3075            boundaries_in_range(Point::new(0, 0)..Point::new(4, 2), &snapshot),
3076            &[
3077                (0, "bbbb\nccccc".to_string(), true),
3078                (2, "ddd\neeee".to_string(), false),
3079                (4, "jj".to_string(), true),
3080            ]
3081        );
3082        assert_eq!(
3083            boundaries_in_range(Point::new(0, 0)..Point::new(2, 0), &snapshot),
3084            &[(0, "bbbb\nccccc".to_string(), true)]
3085        );
3086        assert_eq!(
3087            boundaries_in_range(Point::new(1, 0)..Point::new(1, 5), &snapshot),
3088            &[]
3089        );
3090        assert_eq!(
3091            boundaries_in_range(Point::new(1, 0)..Point::new(2, 0), &snapshot),
3092            &[]
3093        );
3094        assert_eq!(
3095            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3096            &[(2, "ddd\neeee".to_string(), false)]
3097        );
3098        assert_eq!(
3099            boundaries_in_range(Point::new(1, 0)..Point::new(4, 0), &snapshot),
3100            &[(2, "ddd\neeee".to_string(), false)]
3101        );
3102        assert_eq!(
3103            boundaries_in_range(Point::new(2, 0)..Point::new(3, 0), &snapshot),
3104            &[(2, "ddd\neeee".to_string(), false)]
3105        );
3106        assert_eq!(
3107            boundaries_in_range(Point::new(4, 0)..Point::new(4, 2), &snapshot),
3108            &[(4, "jj".to_string(), true)]
3109        );
3110        assert_eq!(
3111            boundaries_in_range(Point::new(4, 2)..Point::new(4, 2), &snapshot),
3112            &[]
3113        );
3114
3115        buffer_1.update(cx, |buffer, cx| {
3116            let text = "\n";
3117            buffer.edit_batched(
3118                [
3119                    (Point::new(0, 0)..Point::new(0, 0), text),
3120                    (Point::new(2, 1)..Point::new(2, 3), text),
3121                ],
3122                cx,
3123            );
3124        });
3125
3126        let snapshot = multibuffer.read(cx).snapshot(cx);
3127        assert_eq!(
3128            snapshot.text(),
3129            concat!(
3130                "bbbb\n", // Preserve newlines
3131                "c\n",    //
3132                "cc\n",   //
3133                "ddd\n",  //
3134                "eeee\n", //
3135                "jj"      //
3136            )
3137        );
3138
3139        assert_eq!(
3140            subscription.consume().into_inner(),
3141            [Edit {
3142                old: 6..8,
3143                new: 6..7
3144            }]
3145        );
3146
3147        let snapshot = multibuffer.read(cx).snapshot(cx);
3148        assert_eq!(
3149            snapshot.clip_point(Point::new(0, 5), Bias::Left),
3150            Point::new(0, 4)
3151        );
3152        assert_eq!(
3153            snapshot.clip_point(Point::new(0, 5), Bias::Right),
3154            Point::new(0, 4)
3155        );
3156        assert_eq!(
3157            snapshot.clip_point(Point::new(5, 1), Bias::Right),
3158            Point::new(5, 1)
3159        );
3160        assert_eq!(
3161            snapshot.clip_point(Point::new(5, 2), Bias::Right),
3162            Point::new(5, 2)
3163        );
3164        assert_eq!(
3165            snapshot.clip_point(Point::new(5, 3), Bias::Right),
3166            Point::new(5, 2)
3167        );
3168
3169        let snapshot = multibuffer.update(cx, |multibuffer, cx| {
3170            let (buffer_2_excerpt_id, _) =
3171                multibuffer.excerpts_for_buffer(&buffer_2, cx)[0].clone();
3172            multibuffer.remove_excerpts(&[buffer_2_excerpt_id], cx);
3173            multibuffer.snapshot(cx)
3174        });
3175
3176        assert_eq!(
3177            snapshot.text(),
3178            concat!(
3179                "bbbb\n", // Preserve newlines
3180                "c\n",    //
3181                "cc\n",   //
3182                "ddd\n",  //
3183                "eeee",   //
3184            )
3185        );
3186
3187        fn boundaries_in_range(
3188            range: Range<Point>,
3189            snapshot: &MultiBufferSnapshot,
3190        ) -> Vec<(u32, String, bool)> {
3191            snapshot
3192                .excerpt_boundaries_in_range(range)
3193                .map(|boundary| {
3194                    (
3195                        boundary.row,
3196                        boundary
3197                            .buffer
3198                            .text_for_range(boundary.range)
3199                            .collect::<String>(),
3200                        boundary.starts_new_buffer,
3201                    )
3202                })
3203                .collect::<Vec<_>>()
3204        }
3205    }
3206
3207    #[gpui::test]
3208    fn test_excerpts_with_context_lines(cx: &mut MutableAppContext) {
3209        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(20, 3, 'a'), cx));
3210        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3211        let anchor_ranges = multibuffer.update(cx, |multibuffer, cx| {
3212            multibuffer.push_excerpts_with_context_lines(
3213                buffer.clone(),
3214                vec![
3215                    Point::new(3, 2)..Point::new(4, 2),
3216                    Point::new(7, 1)..Point::new(7, 3),
3217                    Point::new(15, 0)..Point::new(15, 0),
3218                ],
3219                2,
3220                cx,
3221            )
3222        });
3223
3224        let snapshot = multibuffer.read(cx).snapshot(cx);
3225        assert_eq!(
3226            snapshot.text(),
3227            "bbb\nccc\nddd\neee\nfff\nggg\nhhh\niii\njjj\n\nnnn\nooo\nppp\nqqq\nrrr\n"
3228        );
3229
3230        assert_eq!(
3231            anchor_ranges
3232                .iter()
3233                .map(|range| range.to_point(&snapshot))
3234                .collect::<Vec<_>>(),
3235            vec![
3236                Point::new(2, 2)..Point::new(3, 2),
3237                Point::new(6, 1)..Point::new(6, 3),
3238                Point::new(12, 0)..Point::new(12, 0)
3239            ]
3240        );
3241    }
3242
3243    #[gpui::test]
3244    fn test_empty_excerpt_buffer(cx: &mut MutableAppContext) {
3245        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3246
3247        let snapshot = multibuffer.read(cx).snapshot(cx);
3248        assert_eq!(snapshot.text(), "");
3249        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), &[Some(0)]);
3250        assert_eq!(snapshot.buffer_rows(1).collect::<Vec<_>>(), &[]);
3251    }
3252
3253    #[gpui::test]
3254    fn test_singleton_multibuffer_anchors(cx: &mut MutableAppContext) {
3255        let buffer = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3256        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
3257        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3258        buffer.update(cx, |buffer, cx| {
3259            buffer.edit(0..0, "X", cx);
3260            buffer.edit(5..5, "Y", cx);
3261        });
3262        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3263
3264        assert_eq!(old_snapshot.text(), "abcd");
3265        assert_eq!(new_snapshot.text(), "XabcdY");
3266
3267        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3268        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3269        assert_eq!(old_snapshot.anchor_before(4).to_offset(&new_snapshot), 5);
3270        assert_eq!(old_snapshot.anchor_after(4).to_offset(&new_snapshot), 6);
3271    }
3272
3273    #[gpui::test]
3274    fn test_multibuffer_anchors(cx: &mut MutableAppContext) {
3275        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3276        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "efghi", cx));
3277        let multibuffer = cx.add_model(|cx| {
3278            let mut multibuffer = MultiBuffer::new(0);
3279            multibuffer.push_excerpts(buffer_1.clone(), [0..4], cx);
3280            multibuffer.push_excerpts(buffer_2.clone(), [0..5], cx);
3281            multibuffer
3282        });
3283        let old_snapshot = multibuffer.read(cx).snapshot(cx);
3284
3285        assert_eq!(old_snapshot.anchor_before(0).to_offset(&old_snapshot), 0);
3286        assert_eq!(old_snapshot.anchor_after(0).to_offset(&old_snapshot), 0);
3287        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3288        assert_eq!(Anchor::min().to_offset(&old_snapshot), 0);
3289        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3290        assert_eq!(Anchor::max().to_offset(&old_snapshot), 10);
3291
3292        buffer_1.update(cx, |buffer, cx| {
3293            buffer.edit(0..0, "W", cx);
3294            buffer.edit(5..5, "X", cx);
3295        });
3296        buffer_2.update(cx, |buffer, cx| {
3297            buffer.edit(0..0, "Y", cx);
3298            buffer.edit(6..0, "Z", cx);
3299        });
3300        let new_snapshot = multibuffer.read(cx).snapshot(cx);
3301
3302        assert_eq!(old_snapshot.text(), "abcd\nefghi");
3303        assert_eq!(new_snapshot.text(), "WabcdX\nYefghiZ");
3304
3305        assert_eq!(old_snapshot.anchor_before(0).to_offset(&new_snapshot), 0);
3306        assert_eq!(old_snapshot.anchor_after(0).to_offset(&new_snapshot), 1);
3307        assert_eq!(old_snapshot.anchor_before(1).to_offset(&new_snapshot), 2);
3308        assert_eq!(old_snapshot.anchor_after(1).to_offset(&new_snapshot), 2);
3309        assert_eq!(old_snapshot.anchor_before(2).to_offset(&new_snapshot), 3);
3310        assert_eq!(old_snapshot.anchor_after(2).to_offset(&new_snapshot), 3);
3311        assert_eq!(old_snapshot.anchor_before(5).to_offset(&new_snapshot), 7);
3312        assert_eq!(old_snapshot.anchor_after(5).to_offset(&new_snapshot), 8);
3313        assert_eq!(old_snapshot.anchor_before(10).to_offset(&new_snapshot), 13);
3314        assert_eq!(old_snapshot.anchor_after(10).to_offset(&new_snapshot), 14);
3315    }
3316
3317    #[gpui::test]
3318    fn test_multibuffer_resolving_anchors_after_replacing_their_excerpts(
3319        cx: &mut MutableAppContext,
3320    ) {
3321        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "abcd", cx));
3322        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "ABCDEFGHIJKLMNOP", cx));
3323        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3324
3325        // Create an insertion id in buffer 1 that doesn't exist in buffer 2.
3326        // Add an excerpt from buffer 1 that spans this new insertion.
3327        buffer_1.update(cx, |buffer, cx| buffer.edit(4..4, "123", cx));
3328        let excerpt_id_1 = multibuffer.update(cx, |multibuffer, cx| {
3329            multibuffer
3330                .push_excerpts(buffer_1.clone(), [0..7], cx)
3331                .pop()
3332                .unwrap()
3333        });
3334
3335        let snapshot_1 = multibuffer.read(cx).snapshot(cx);
3336        assert_eq!(snapshot_1.text(), "abcd123");
3337
3338        // Replace the buffer 1 excerpt with new excerpts from buffer 2.
3339        let (excerpt_id_2, excerpt_id_3) = multibuffer.update(cx, |multibuffer, cx| {
3340            multibuffer.remove_excerpts([&excerpt_id_1], cx);
3341            let mut ids = multibuffer
3342                .push_excerpts(buffer_2.clone(), [0..4, 6..10, 12..16], cx)
3343                .into_iter();
3344            (ids.next().unwrap(), ids.next().unwrap())
3345        });
3346        let snapshot_2 = multibuffer.read(cx).snapshot(cx);
3347        assert_eq!(snapshot_2.text(), "ABCD\nGHIJ\nMNOP");
3348
3349        // The old excerpt id doesn't get reused.
3350        assert_ne!(excerpt_id_2, excerpt_id_1);
3351
3352        // Resolve some anchors from the previous snapshot in the new snapshot.
3353        // Although there is still an excerpt with the same id, it is for
3354        // a different buffer, so we don't attempt to resolve the old text
3355        // anchor in the new buffer.
3356        assert_eq!(
3357            snapshot_2.summary_for_anchor::<usize>(&snapshot_1.anchor_before(2)),
3358            0
3359        );
3360        assert_eq!(
3361            snapshot_2.summaries_for_anchors::<usize, _>(&[
3362                snapshot_1.anchor_before(2),
3363                snapshot_1.anchor_after(3)
3364            ]),
3365            vec![0, 0]
3366        );
3367        let refresh =
3368            snapshot_2.refresh_anchors(&[snapshot_1.anchor_before(2), snapshot_1.anchor_after(3)]);
3369        assert_eq!(
3370            refresh,
3371            &[
3372                (0, snapshot_2.anchor_before(0), false),
3373                (1, snapshot_2.anchor_after(0), false),
3374            ]
3375        );
3376
3377        // Replace the middle excerpt with a smaller excerpt in buffer 2,
3378        // that intersects the old excerpt.
3379        let excerpt_id_5 = multibuffer.update(cx, |multibuffer, cx| {
3380            multibuffer.remove_excerpts([&excerpt_id_3], cx);
3381            multibuffer
3382                .insert_excerpts_after(&excerpt_id_3, buffer_2.clone(), [5..8], cx)
3383                .pop()
3384                .unwrap()
3385        });
3386
3387        let snapshot_3 = multibuffer.read(cx).snapshot(cx);
3388        assert_eq!(snapshot_3.text(), "ABCD\nFGH\nMNOP");
3389        assert_ne!(excerpt_id_5, excerpt_id_3);
3390
3391        // Resolve some anchors from the previous snapshot in the new snapshot.
3392        // The anchor in the middle excerpt snaps to the beginning of the
3393        // excerpt, since it is not
3394        let anchors = [
3395            snapshot_2.anchor_before(0),
3396            snapshot_2.anchor_after(2),
3397            snapshot_2.anchor_after(6),
3398            snapshot_2.anchor_after(14),
3399        ];
3400        assert_eq!(
3401            snapshot_3.summaries_for_anchors::<usize, _>(&anchors),
3402            &[0, 2, 5, 13]
3403        );
3404
3405        let new_anchors = snapshot_3.refresh_anchors(&anchors);
3406        assert_eq!(
3407            new_anchors.iter().map(|a| (a.0, a.2)).collect::<Vec<_>>(),
3408            &[(0, true), (1, true), (2, true), (3, true)]
3409        );
3410        assert_eq!(
3411            snapshot_3.summaries_for_anchors::<usize, _>(new_anchors.iter().map(|a| &a.1)),
3412            &[0, 2, 7, 13]
3413        );
3414    }
3415
3416    #[gpui::test(iterations = 100)]
3417    fn test_random_multibuffer(cx: &mut MutableAppContext, mut rng: StdRng) {
3418        let operations = env::var("OPERATIONS")
3419            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
3420            .unwrap_or(10);
3421
3422        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
3423        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3424        let mut excerpt_ids = Vec::new();
3425        let mut expected_excerpts = Vec::<(ModelHandle<Buffer>, Range<text::Anchor>)>::new();
3426        let mut anchors = Vec::new();
3427        let mut old_versions = Vec::new();
3428
3429        for _ in 0..operations {
3430            match rng.gen_range(0..100) {
3431                0..=19 if !buffers.is_empty() => {
3432                    let buffer = buffers.choose(&mut rng).unwrap();
3433                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 5, cx));
3434                }
3435                20..=29 if !expected_excerpts.is_empty() => {
3436                    let mut ids_to_remove = vec![];
3437                    for _ in 0..rng.gen_range(1..=3) {
3438                        if expected_excerpts.is_empty() {
3439                            break;
3440                        }
3441
3442                        let ix = rng.gen_range(0..expected_excerpts.len());
3443                        ids_to_remove.push(excerpt_ids.remove(ix));
3444                        let (buffer, range) = expected_excerpts.remove(ix);
3445                        let buffer = buffer.read(cx);
3446                        log::info!(
3447                            "Removing excerpt {}: {:?}",
3448                            ix,
3449                            buffer
3450                                .text_for_range(range.to_offset(&buffer))
3451                                .collect::<String>(),
3452                        );
3453                    }
3454                    ids_to_remove.sort_unstable();
3455                    multibuffer.update(cx, |multibuffer, cx| {
3456                        multibuffer.remove_excerpts(&ids_to_remove, cx)
3457                    });
3458                }
3459                30..=39 if !expected_excerpts.is_empty() => {
3460                    let multibuffer = multibuffer.read(cx).read(cx);
3461                    let offset =
3462                        multibuffer.clip_offset(rng.gen_range(0..=multibuffer.len()), Bias::Left);
3463                    let bias = if rng.gen() { Bias::Left } else { Bias::Right };
3464                    log::info!("Creating anchor at {} with bias {:?}", offset, bias);
3465                    anchors.push(multibuffer.anchor_at(offset, bias));
3466                    anchors.sort_by(|a, b| a.cmp(&b, &multibuffer));
3467                }
3468                40..=44 if !anchors.is_empty() => {
3469                    let multibuffer = multibuffer.read(cx).read(cx);
3470                    let prev_len = anchors.len();
3471                    anchors = multibuffer
3472                        .refresh_anchors(&anchors)
3473                        .into_iter()
3474                        .map(|a| a.1)
3475                        .collect();
3476
3477                    // Ensure the newly-refreshed anchors point to a valid excerpt and don't
3478                    // overshoot its boundaries.
3479                    assert_eq!(anchors.len(), prev_len);
3480                    let mut cursor = multibuffer.excerpts.cursor::<Option<&ExcerptId>>();
3481                    for anchor in &anchors {
3482                        if anchor.excerpt_id == ExcerptId::min()
3483                            || anchor.excerpt_id == ExcerptId::max()
3484                        {
3485                            continue;
3486                        }
3487
3488                        cursor.seek_forward(&Some(&anchor.excerpt_id), Bias::Left, &());
3489                        let excerpt = cursor.item().unwrap();
3490                        assert_eq!(excerpt.id, anchor.excerpt_id);
3491                        assert!(excerpt.contains(anchor));
3492                    }
3493                }
3494                _ => {
3495                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
3496                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
3497                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
3498                        buffers.last().unwrap()
3499                    } else {
3500                        buffers.choose(&mut rng).unwrap()
3501                    };
3502
3503                    let buffer = buffer_handle.read(cx);
3504                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
3505                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3506                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
3507                    let prev_excerpt_ix = rng.gen_range(0..=expected_excerpts.len());
3508                    let prev_excerpt_id = excerpt_ids
3509                        .get(prev_excerpt_ix)
3510                        .cloned()
3511                        .unwrap_or(ExcerptId::max());
3512                    let excerpt_ix = (prev_excerpt_ix + 1).min(expected_excerpts.len());
3513
3514                    log::info!(
3515                        "Inserting excerpt at {} of {} for buffer {}: {:?}[{:?}] = {:?}",
3516                        excerpt_ix,
3517                        expected_excerpts.len(),
3518                        buffer_handle.id(),
3519                        buffer.text(),
3520                        start_ix..end_ix,
3521                        &buffer.text()[start_ix..end_ix]
3522                    );
3523
3524                    let excerpt_id = multibuffer.update(cx, |multibuffer, cx| {
3525                        multibuffer
3526                            .insert_excerpts_after(
3527                                &prev_excerpt_id,
3528                                buffer_handle.clone(),
3529                                [start_ix..end_ix],
3530                                cx,
3531                            )
3532                            .pop()
3533                            .unwrap()
3534                    });
3535
3536                    excerpt_ids.insert(excerpt_ix, excerpt_id);
3537                    expected_excerpts.insert(excerpt_ix, (buffer_handle.clone(), anchor_range));
3538                }
3539            }
3540
3541            if rng.gen_bool(0.3) {
3542                multibuffer.update(cx, |multibuffer, cx| {
3543                    old_versions.push((multibuffer.snapshot(cx), multibuffer.subscribe()));
3544                })
3545            }
3546
3547            let snapshot = multibuffer.read(cx).snapshot(cx);
3548
3549            let mut excerpt_starts = Vec::new();
3550            let mut expected_text = String::new();
3551            let mut expected_buffer_rows = Vec::new();
3552            for (buffer, range) in &expected_excerpts {
3553                let buffer = buffer.read(cx);
3554                let buffer_range = range.to_offset(buffer);
3555
3556                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
3557                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
3558                expected_text.push('\n');
3559
3560                let buffer_row_range = buffer.offset_to_point(buffer_range.start).row
3561                    ..=buffer.offset_to_point(buffer_range.end).row;
3562                for row in buffer_row_range {
3563                    expected_buffer_rows.push(Some(row));
3564                }
3565            }
3566            // Remove final trailing newline.
3567            if !expected_excerpts.is_empty() {
3568                expected_text.pop();
3569            }
3570
3571            // Always report one buffer row
3572            if expected_buffer_rows.is_empty() {
3573                expected_buffer_rows.push(Some(0));
3574            }
3575
3576            assert_eq!(snapshot.text(), expected_text);
3577            log::info!("MultiBuffer text: {:?}", expected_text);
3578
3579            assert_eq!(
3580                snapshot.buffer_rows(0).collect::<Vec<_>>(),
3581                expected_buffer_rows,
3582            );
3583
3584            for _ in 0..5 {
3585                let start_row = rng.gen_range(0..=expected_buffer_rows.len());
3586                assert_eq!(
3587                    snapshot.buffer_rows(start_row as u32).collect::<Vec<_>>(),
3588                    &expected_buffer_rows[start_row..],
3589                    "buffer_rows({})",
3590                    start_row
3591                );
3592            }
3593
3594            assert_eq!(
3595                snapshot.max_buffer_row(),
3596                expected_buffer_rows
3597                    .into_iter()
3598                    .filter_map(|r| r)
3599                    .max()
3600                    .unwrap()
3601            );
3602
3603            let mut excerpt_starts = excerpt_starts.into_iter();
3604            for (buffer, range) in &expected_excerpts {
3605                let buffer_id = buffer.id();
3606                let buffer = buffer.read(cx);
3607                let buffer_range = range.to_offset(buffer);
3608                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
3609                let buffer_start_point_utf16 =
3610                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
3611
3612                let excerpt_start = excerpt_starts.next().unwrap();
3613                let mut offset = excerpt_start.bytes;
3614                let mut buffer_offset = buffer_range.start;
3615                let mut point = excerpt_start.lines;
3616                let mut buffer_point = buffer_start_point;
3617                let mut point_utf16 = excerpt_start.lines_utf16;
3618                let mut buffer_point_utf16 = buffer_start_point_utf16;
3619                for ch in buffer
3620                    .snapshot()
3621                    .chunks(buffer_range.clone(), false)
3622                    .flat_map(|c| c.text.chars())
3623                {
3624                    for _ in 0..ch.len_utf8() {
3625                        let left_offset = snapshot.clip_offset(offset, Bias::Left);
3626                        let right_offset = snapshot.clip_offset(offset, Bias::Right);
3627                        let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
3628                        let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
3629                        assert_eq!(
3630                            left_offset,
3631                            excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
3632                            "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
3633                            offset,
3634                            buffer_id,
3635                            buffer_offset,
3636                        );
3637                        assert_eq!(
3638                            right_offset,
3639                            excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
3640                            "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
3641                            offset,
3642                            buffer_id,
3643                            buffer_offset,
3644                        );
3645
3646                        let left_point = snapshot.clip_point(point, Bias::Left);
3647                        let right_point = snapshot.clip_point(point, Bias::Right);
3648                        let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
3649                        let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
3650                        assert_eq!(
3651                            left_point,
3652                            excerpt_start.lines + (buffer_left_point - buffer_start_point),
3653                            "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
3654                            point,
3655                            buffer_id,
3656                            buffer_point,
3657                        );
3658                        assert_eq!(
3659                            right_point,
3660                            excerpt_start.lines + (buffer_right_point - buffer_start_point),
3661                            "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
3662                            point,
3663                            buffer_id,
3664                            buffer_point,
3665                        );
3666
3667                        assert_eq!(
3668                            snapshot.point_to_offset(left_point),
3669                            left_offset,
3670                            "point_to_offset({:?})",
3671                            left_point,
3672                        );
3673                        assert_eq!(
3674                            snapshot.offset_to_point(left_offset),
3675                            left_point,
3676                            "offset_to_point({:?})",
3677                            left_offset,
3678                        );
3679
3680                        offset += 1;
3681                        buffer_offset += 1;
3682                        if ch == '\n' {
3683                            point += Point::new(1, 0);
3684                            buffer_point += Point::new(1, 0);
3685                        } else {
3686                            point += Point::new(0, 1);
3687                            buffer_point += Point::new(0, 1);
3688                        }
3689                    }
3690
3691                    for _ in 0..ch.len_utf16() {
3692                        let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
3693                        let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
3694                        let buffer_left_point_utf16 =
3695                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
3696                        let buffer_right_point_utf16 =
3697                            buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
3698                        assert_eq!(
3699                            left_point_utf16,
3700                            excerpt_start.lines_utf16
3701                                + (buffer_left_point_utf16 - buffer_start_point_utf16),
3702                            "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
3703                            point_utf16,
3704                            buffer_id,
3705                            buffer_point_utf16,
3706                        );
3707                        assert_eq!(
3708                            right_point_utf16,
3709                            excerpt_start.lines_utf16
3710                                + (buffer_right_point_utf16 - buffer_start_point_utf16),
3711                            "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
3712                            point_utf16,
3713                            buffer_id,
3714                            buffer_point_utf16,
3715                        );
3716
3717                        if ch == '\n' {
3718                            point_utf16 += PointUtf16::new(1, 0);
3719                            buffer_point_utf16 += PointUtf16::new(1, 0);
3720                        } else {
3721                            point_utf16 += PointUtf16::new(0, 1);
3722                            buffer_point_utf16 += PointUtf16::new(0, 1);
3723                        }
3724                    }
3725                }
3726            }
3727
3728            for (row, line) in expected_text.split('\n').enumerate() {
3729                assert_eq!(
3730                    snapshot.line_len(row as u32),
3731                    line.len() as u32,
3732                    "line_len({}).",
3733                    row
3734                );
3735            }
3736
3737            let text_rope = Rope::from(expected_text.as_str());
3738            for _ in 0..10 {
3739                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3740                let start_ix = text_rope.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
3741
3742                let text_for_range = snapshot
3743                    .text_for_range(start_ix..end_ix)
3744                    .collect::<String>();
3745                assert_eq!(
3746                    text_for_range,
3747                    &expected_text[start_ix..end_ix],
3748                    "incorrect text for range {:?}",
3749                    start_ix..end_ix
3750                );
3751
3752                let excerpted_buffer_ranges = multibuffer
3753                    .read(cx)
3754                    .range_to_buffer_ranges(start_ix..end_ix, cx);
3755                let excerpted_buffers_text = excerpted_buffer_ranges
3756                    .into_iter()
3757                    .map(|(buffer, buffer_range)| {
3758                        buffer
3759                            .read(cx)
3760                            .text_for_range(buffer_range)
3761                            .collect::<String>()
3762                    })
3763                    .collect::<Vec<_>>()
3764                    .join("\n");
3765                assert_eq!(excerpted_buffers_text, text_for_range);
3766
3767                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
3768                assert_eq!(
3769                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
3770                    expected_summary,
3771                    "incorrect summary for range {:?}",
3772                    start_ix..end_ix
3773                );
3774            }
3775
3776            // Anchor resolution
3777            let summaries = snapshot.summaries_for_anchors::<usize, _>(&anchors);
3778            assert_eq!(anchors.len(), summaries.len());
3779            for (anchor, resolved_offset) in anchors.iter().zip(summaries) {
3780                assert!(resolved_offset <= snapshot.len());
3781                assert_eq!(
3782                    snapshot.summary_for_anchor::<usize>(anchor),
3783                    resolved_offset
3784                );
3785            }
3786
3787            for _ in 0..10 {
3788                let end_ix = text_rope.clip_offset(rng.gen_range(0..=text_rope.len()), Bias::Right);
3789                assert_eq!(
3790                    snapshot.reversed_chars_at(end_ix).collect::<String>(),
3791                    expected_text[..end_ix].chars().rev().collect::<String>(),
3792                );
3793            }
3794
3795            for _ in 0..10 {
3796                let end_ix = rng.gen_range(0..=text_rope.len());
3797                let start_ix = rng.gen_range(0..=end_ix);
3798                assert_eq!(
3799                    snapshot
3800                        .bytes_in_range(start_ix..end_ix)
3801                        .flatten()
3802                        .copied()
3803                        .collect::<Vec<_>>(),
3804                    expected_text.as_bytes()[start_ix..end_ix].to_vec(),
3805                    "bytes_in_range({:?})",
3806                    start_ix..end_ix,
3807                );
3808            }
3809        }
3810
3811        let snapshot = multibuffer.read(cx).snapshot(cx);
3812        for (old_snapshot, subscription) in old_versions {
3813            let edits = subscription.consume().into_inner();
3814
3815            log::info!(
3816                "applying subscription edits to old text: {:?}: {:?}",
3817                old_snapshot.text(),
3818                edits,
3819            );
3820
3821            let mut text = old_snapshot.text();
3822            for edit in edits {
3823                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
3824                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
3825            }
3826            assert_eq!(text.to_string(), snapshot.text());
3827        }
3828    }
3829
3830    #[gpui::test]
3831    fn test_history(cx: &mut MutableAppContext) {
3832        cx.set_global(Settings::test(cx));
3833        let buffer_1 = cx.add_model(|cx| Buffer::new(0, "1234", cx));
3834        let buffer_2 = cx.add_model(|cx| Buffer::new(0, "5678", cx));
3835        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
3836        let group_interval = multibuffer.read(cx).history.group_interval;
3837        multibuffer.update(cx, |multibuffer, cx| {
3838            multibuffer.push_excerpts(buffer_1.clone(), [0..buffer_1.read(cx).len()], cx);
3839            multibuffer.push_excerpts(buffer_2.clone(), [0..buffer_2.read(cx).len()], cx);
3840        });
3841
3842        let mut now = Instant::now();
3843
3844        multibuffer.update(cx, |multibuffer, cx| {
3845            multibuffer.start_transaction_at(now, cx);
3846            multibuffer.edit_batched(
3847                [
3848                    (Point::new(0, 0)..Point::new(0, 0), "A"),
3849                    (Point::new(1, 0)..Point::new(1, 0), "A"),
3850                ],
3851                cx,
3852            );
3853            multibuffer.edit_batched(
3854                [
3855                    (Point::new(0, 1)..Point::new(0, 1), "B"),
3856                    (Point::new(1, 1)..Point::new(1, 1), "B"),
3857                ],
3858                cx,
3859            );
3860            multibuffer.end_transaction_at(now, cx);
3861            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3862
3863            // Edit buffer 1 through the multibuffer
3864            now += 2 * group_interval;
3865            multibuffer.start_transaction_at(now, cx);
3866            multibuffer.edit(2..2, "C", cx);
3867            multibuffer.end_transaction_at(now, cx);
3868            assert_eq!(multibuffer.read(cx).text(), "ABC1234\nAB5678");
3869
3870            // Edit buffer 1 independently
3871            buffer_1.update(cx, |buffer_1, cx| {
3872                buffer_1.start_transaction_at(now);
3873                buffer_1.edit(3..3, "D", cx);
3874                buffer_1.end_transaction_at(now, cx);
3875
3876                now += 2 * group_interval;
3877                buffer_1.start_transaction_at(now);
3878                buffer_1.edit(4..4, "E", cx);
3879                buffer_1.end_transaction_at(now, cx);
3880            });
3881            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
3882
3883            // An undo in the multibuffer undoes the multibuffer transaction
3884            // and also any individual buffer edits that have occured since
3885            // that transaction.
3886            multibuffer.undo(cx);
3887            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3888
3889            multibuffer.undo(cx);
3890            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3891
3892            multibuffer.redo(cx);
3893            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3894
3895            multibuffer.redo(cx);
3896            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\nAB5678");
3897
3898            // Undo buffer 2 independently.
3899            buffer_2.update(cx, |buffer_2, cx| buffer_2.undo(cx));
3900            assert_eq!(multibuffer.read(cx).text(), "ABCDE1234\n5678");
3901
3902            // An undo in the multibuffer undoes the components of the
3903            // the last multibuffer transaction that are not already undone.
3904            multibuffer.undo(cx);
3905            assert_eq!(multibuffer.read(cx).text(), "AB1234\n5678");
3906
3907            multibuffer.undo(cx);
3908            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3909
3910            multibuffer.redo(cx);
3911            assert_eq!(multibuffer.read(cx).text(), "AB1234\nAB5678");
3912
3913            buffer_1.update(cx, |buffer_1, cx| buffer_1.redo(cx));
3914            assert_eq!(multibuffer.read(cx).text(), "ABCD1234\nAB5678");
3915
3916            multibuffer.undo(cx);
3917            assert_eq!(multibuffer.read(cx).text(), "1234\n5678");
3918        });
3919    }
3920}