multi_buffer.rs

   1mod anchor;
   2
   3pub use anchor::{Anchor, AnchorRangeExt};
   4use anyhow::Result;
   5use clock::ReplicaId;
   6use collections::HashMap;
   7use gpui::{AppContext, Entity, ModelContext, ModelHandle, MutableAppContext, Task};
   8use language::{
   9    Buffer, BufferChunks, BufferSnapshot, Chunk, DiagnosticEntry, Event, File, Language, Selection,
  10    ToOffset as _, ToPoint as _, TransactionId,
  11};
  12use std::{
  13    cell::{Ref, RefCell},
  14    cmp, io,
  15    iter::{FromIterator, Peekable},
  16    ops::{Range, Sub},
  17    sync::Arc,
  18    time::{Duration, Instant, SystemTime},
  19};
  20use sum_tree::{Bias, Cursor, SumTree};
  21use text::{
  22    locator::Locator,
  23    rope::TextDimension,
  24    subscription::{Subscription, Topic},
  25    AnchorRangeExt as _, Edit, Point, PointUtf16, TextSummary,
  26};
  27use theme::SyntaxTheme;
  28
  29const NEWLINES: &'static [u8] = &[b'\n'; u8::MAX as usize];
  30
  31pub type ExcerptId = Locator;
  32
  33pub struct MultiBuffer {
  34    snapshot: RefCell<MultiBufferSnapshot>,
  35    buffers: HashMap<usize, BufferState>,
  36    subscriptions: Topic,
  37    singleton: bool,
  38    replica_id: ReplicaId,
  39}
  40
  41pub trait ToOffset: 'static {
  42    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> usize;
  43}
  44
  45pub trait ToPoint: 'static {
  46    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
  47}
  48
  49pub trait FromAnchor: 'static {
  50    fn from_anchor(anchor: &Anchor, snapshot: &MultiBufferSnapshot) -> Self;
  51}
  52
  53#[derive(Debug)]
  54struct BufferState {
  55    buffer: ModelHandle<Buffer>,
  56    last_version: clock::Global,
  57    last_parse_count: usize,
  58    last_diagnostics_update_count: usize,
  59    excerpts: Vec<ExcerptId>,
  60}
  61
  62#[derive(Clone, Default)]
  63pub struct MultiBufferSnapshot {
  64    excerpts: SumTree<Excerpt>,
  65    parse_count: usize,
  66    diagnostics_update_count: usize,
  67}
  68
  69pub struct ExcerptProperties<'a, T> {
  70    pub buffer: &'a ModelHandle<Buffer>,
  71    pub range: Range<T>,
  72    pub header_height: u8,
  73}
  74
  75#[derive(Clone)]
  76struct Excerpt {
  77    id: ExcerptId,
  78    buffer_id: usize,
  79    buffer: BufferSnapshot,
  80    range: Range<text::Anchor>,
  81    text_summary: TextSummary,
  82    header_height: u8,
  83    has_trailing_newline: bool,
  84}
  85
  86#[derive(Clone, Debug, Default)]
  87struct ExcerptSummary {
  88    excerpt_id: ExcerptId,
  89    text: TextSummary,
  90}
  91
  92pub struct MultiBufferChunks<'a> {
  93    range: Range<usize>,
  94    cursor: Cursor<'a, Excerpt, usize>,
  95    header_height: u8,
  96    has_trailing_newline: bool,
  97    excerpt_chunks: Option<BufferChunks<'a>>,
  98    theme: Option<&'a SyntaxTheme>,
  99}
 100
 101pub struct MultiBufferBytes<'a> {
 102    chunks: Peekable<MultiBufferChunks<'a>>,
 103}
 104
 105impl MultiBuffer {
 106    pub fn new(replica_id: ReplicaId) -> Self {
 107        Self {
 108            snapshot: Default::default(),
 109            buffers: Default::default(),
 110            subscriptions: Default::default(),
 111            singleton: false,
 112            replica_id,
 113        }
 114    }
 115
 116    pub fn singleton(buffer: ModelHandle<Buffer>, cx: &mut ModelContext<Self>) -> Self {
 117        let mut this = Self::new(buffer.read(cx).replica_id());
 118        this.singleton = true;
 119        this.push_excerpt(
 120            ExcerptProperties {
 121                buffer: &buffer,
 122                range: text::Anchor::min()..text::Anchor::max(),
 123                header_height: 0,
 124            },
 125            cx,
 126        );
 127        this
 128    }
 129
 130    pub fn build_simple(text: &str, cx: &mut MutableAppContext) -> ModelHandle<Self> {
 131        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
 132        cx.add_model(|cx| Self::singleton(buffer, cx))
 133    }
 134
 135    pub fn replica_id(&self) -> ReplicaId {
 136        self.replica_id
 137    }
 138
 139    pub fn transaction_group_interval(&self, cx: &AppContext) -> Duration {
 140        self.as_singleton()
 141            .unwrap()
 142            .read(cx)
 143            .transaction_group_interval()
 144    }
 145
 146    pub fn snapshot(&self, cx: &AppContext) -> MultiBufferSnapshot {
 147        self.sync(cx);
 148        self.snapshot.borrow().clone()
 149    }
 150
 151    pub fn read(&self, cx: &AppContext) -> Ref<MultiBufferSnapshot> {
 152        self.sync(cx);
 153        self.snapshot.borrow()
 154    }
 155
 156    pub fn as_singleton(&self) -> Option<&ModelHandle<Buffer>> {
 157        if self.buffers.len() == 1 {
 158            return Some(&self.buffers.values().next().unwrap().buffer);
 159        } else {
 160            None
 161        }
 162    }
 163
 164    pub fn subscribe(&mut self) -> Subscription {
 165        self.subscriptions.subscribe()
 166    }
 167
 168    pub fn edit<I, S, T>(&mut self, ranges: I, new_text: T, cx: &mut ModelContext<Self>)
 169    where
 170        I: IntoIterator<Item = Range<S>>,
 171        S: ToOffset,
 172        T: Into<String>,
 173    {
 174        self.edit_internal(ranges, new_text, false, cx)
 175    }
 176
 177    pub fn edit_with_autoindent<I, S, T>(
 178        &mut self,
 179        ranges: I,
 180        new_text: T,
 181        cx: &mut ModelContext<Self>,
 182    ) where
 183        I: IntoIterator<Item = Range<S>>,
 184        S: ToOffset,
 185        T: Into<String>,
 186    {
 187        self.edit_internal(ranges, new_text, true, cx)
 188    }
 189
 190    pub fn edit_internal<I, S, T>(
 191        &mut self,
 192        ranges_iter: I,
 193        new_text: T,
 194        autoindent: bool,
 195        cx: &mut ModelContext<Self>,
 196    ) where
 197        I: IntoIterator<Item = Range<S>>,
 198        S: ToOffset,
 199        T: Into<String>,
 200    {
 201        if let Some(buffer) = self.as_singleton() {
 202            let snapshot = self.read(cx);
 203            let ranges = ranges_iter
 204                .into_iter()
 205                .map(|range| range.start.to_offset(&snapshot)..range.end.to_offset(&snapshot));
 206            return buffer.update(cx, |buffer, cx| {
 207                if autoindent {
 208                    buffer.edit_with_autoindent(ranges, new_text, cx)
 209                } else {
 210                    buffer.edit(ranges, new_text, cx)
 211                }
 212            });
 213        }
 214
 215        let snapshot = self.read(cx);
 216        let mut buffer_edits: HashMap<usize, Vec<(Range<usize>, bool)>> = Default::default();
 217        let mut cursor = snapshot.excerpts.cursor::<usize>();
 218        for range in ranges_iter {
 219            let start = range.start.to_offset(&snapshot);
 220            let end = range.end.to_offset(&snapshot);
 221            cursor.seek(&start, Bias::Right, &());
 222            let start_excerpt = cursor.item().expect("start offset out of bounds");
 223            let start_overshoot =
 224                (start - cursor.start()).saturating_sub(start_excerpt.header_height as usize);
 225            let buffer_start =
 226                start_excerpt.range.start.to_offset(&start_excerpt.buffer) + start_overshoot;
 227
 228            cursor.seek(&end, Bias::Right, &());
 229            let end_excerpt = cursor.item().expect("end offset out of bounds");
 230            let end_overshoot =
 231                (end - cursor.start()).saturating_sub(end_excerpt.header_height as usize);
 232            let buffer_end = end_excerpt.range.start.to_offset(&end_excerpt.buffer) + end_overshoot;
 233
 234            if start_excerpt.id == end_excerpt.id {
 235                buffer_edits
 236                    .entry(start_excerpt.buffer_id)
 237                    .or_insert(Vec::new())
 238                    .push((buffer_start..buffer_end, true));
 239            } else {
 240                let start_excerpt_range =
 241                    buffer_start..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 242                let end_excerpt_range =
 243                    end_excerpt.range.start.to_offset(&end_excerpt.buffer)..buffer_end;
 244                buffer_edits
 245                    .entry(start_excerpt.buffer_id)
 246                    .or_insert(Vec::new())
 247                    .push((start_excerpt_range, true));
 248                buffer_edits
 249                    .entry(end_excerpt.buffer_id)
 250                    .or_insert(Vec::new())
 251                    .push((end_excerpt_range, false));
 252
 253                cursor.seek(&start, Bias::Right, &());
 254                cursor.next(&());
 255                while let Some(excerpt) = cursor.item() {
 256                    if excerpt.id == end_excerpt.id {
 257                        break;
 258                    }
 259
 260                    let excerpt_range = start_excerpt.range.end.to_offset(&start_excerpt.buffer)
 261                        ..start_excerpt.range.end.to_offset(&start_excerpt.buffer);
 262                    buffer_edits
 263                        .entry(excerpt.buffer_id)
 264                        .or_insert(Vec::new())
 265                        .push((excerpt_range, false));
 266                    cursor.next(&());
 267                }
 268            }
 269        }
 270
 271        let new_text = new_text.into();
 272        for (buffer_id, mut edits) in buffer_edits {
 273            edits.sort_unstable_by_key(|(range, _)| range.start);
 274            self.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
 275                let mut edits = edits.into_iter().peekable();
 276                let mut insertions = Vec::new();
 277                let mut deletions = Vec::new();
 278                while let Some((mut range, mut is_insertion)) = edits.next() {
 279                    while let Some((next_range, next_is_insertion)) = edits.peek() {
 280                        if range.end >= next_range.start {
 281                            range.end = cmp::max(next_range.end, range.end);
 282                            is_insertion |= *next_is_insertion;
 283                            edits.next();
 284                        } else {
 285                            break;
 286                        }
 287                    }
 288
 289                    if is_insertion {
 290                        insertions.push(
 291                            buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 292                        );
 293                    } else {
 294                        deletions.push(
 295                            buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
 296                        );
 297                    }
 298                }
 299
 300                if autoindent {
 301                    buffer.edit_with_autoindent(deletions, "", cx);
 302                    buffer.edit_with_autoindent(insertions, new_text.clone(), cx);
 303                } else {
 304                    buffer.edit(deletions, "", cx);
 305                    buffer.edit(insertions, new_text.clone(), cx);
 306                }
 307            })
 308        }
 309    }
 310
 311    pub fn start_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 312        self.start_transaction_at(Instant::now(), cx)
 313    }
 314
 315    pub(crate) fn start_transaction_at(
 316        &mut self,
 317        now: Instant,
 318        cx: &mut ModelContext<Self>,
 319    ) -> Option<TransactionId> {
 320        // TODO
 321        self.as_singleton()
 322            .unwrap()
 323            .update(cx, |buffer, _| buffer.start_transaction_at(now))
 324    }
 325
 326    pub fn end_transaction(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 327        // TODO
 328        self.as_singleton()
 329            .unwrap()
 330            .update(cx, |buffer, cx| buffer.end_transaction(cx))
 331    }
 332
 333    pub(crate) fn end_transaction_at(
 334        &mut self,
 335        now: Instant,
 336        cx: &mut ModelContext<Self>,
 337    ) -> Option<TransactionId> {
 338        // TODO
 339        self.as_singleton()
 340            .unwrap()
 341            .update(cx, |buffer, cx| buffer.end_transaction_at(now, cx))
 342    }
 343
 344    pub fn set_active_selections(
 345        &mut self,
 346        selections: &[Selection<Anchor>],
 347        cx: &mut ModelContext<Self>,
 348    ) {
 349        // TODO
 350        let this = self.read(cx);
 351        self.as_singleton().unwrap().update(cx, |buffer, cx| {
 352            let buffer_snapshot = buffer.snapshot();
 353            let selections = selections.iter().map(|selection| Selection {
 354                id: selection.id,
 355                start: buffer_snapshot.anchor_before(selection.start.to_offset(&this)),
 356                end: buffer_snapshot.anchor_before(selection.end.to_offset(&this)),
 357                reversed: selection.reversed,
 358                goal: selection.goal,
 359            });
 360            buffer.set_active_selections(Arc::from_iter(selections), cx);
 361        });
 362    }
 363
 364    pub fn remove_active_selections(&mut self, cx: &mut ModelContext<Self>) {
 365        for buffer in self.buffers.values() {
 366            buffer
 367                .buffer
 368                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
 369        }
 370    }
 371
 372    pub fn undo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 373        // TODO
 374        self.as_singleton()
 375            .unwrap()
 376            .update(cx, |buffer, cx| buffer.undo(cx))
 377    }
 378
 379    pub fn redo(&mut self, cx: &mut ModelContext<Self>) -> Option<TransactionId> {
 380        // TODO
 381        self.as_singleton()
 382            .unwrap()
 383            .update(cx, |buffer, cx| buffer.redo(cx))
 384    }
 385
 386    pub fn push_excerpt<O>(
 387        &mut self,
 388        props: ExcerptProperties<O>,
 389        cx: &mut ModelContext<Self>,
 390    ) -> ExcerptId
 391    where
 392        O: text::ToOffset,
 393    {
 394        self.sync(cx);
 395
 396        let buffer = &props.buffer;
 397        cx.subscribe(buffer, Self::on_buffer_event).detach();
 398
 399        let buffer = props.buffer.read(cx);
 400        let range = buffer.anchor_before(&props.range.start)..buffer.anchor_after(&props.range.end);
 401        let mut snapshot = self.snapshot.borrow_mut();
 402        let prev_id = snapshot.excerpts.last().map(|e| &e.id);
 403        let id = ExcerptId::between(prev_id.unwrap_or(&ExcerptId::min()), &ExcerptId::max());
 404
 405        let edit_start = snapshot.excerpts.summary().text.bytes;
 406        let excerpt = Excerpt::new(
 407            id.clone(),
 408            props.buffer.id(),
 409            buffer.snapshot(),
 410            range,
 411            props.header_height,
 412            !self.singleton,
 413        );
 414        let edit = Edit {
 415            old: edit_start..edit_start,
 416            new: edit_start..edit_start + excerpt.text_summary.bytes,
 417        };
 418        snapshot.excerpts.push(excerpt, &());
 419        self.buffers
 420            .entry(props.buffer.id())
 421            .or_insert_with(|| BufferState {
 422                buffer: props.buffer.clone(),
 423                last_version: buffer.version(),
 424                last_parse_count: buffer.parse_count(),
 425                last_diagnostics_update_count: buffer.diagnostics_update_count(),
 426                excerpts: Default::default(),
 427            })
 428            .excerpts
 429            .push(id.clone());
 430
 431        self.subscriptions.publish_mut([edit]);
 432
 433        id
 434    }
 435
 436    fn on_buffer_event(
 437        &mut self,
 438        _: ModelHandle<Buffer>,
 439        event: &Event,
 440        cx: &mut ModelContext<Self>,
 441    ) {
 442        cx.emit(event.clone());
 443    }
 444
 445    pub fn save(
 446        &mut self,
 447        cx: &mut ModelContext<Self>,
 448    ) -> Result<Task<Result<(clock::Global, SystemTime)>>> {
 449        self.as_singleton()
 450            .unwrap()
 451            .update(cx, |buffer, cx| buffer.save(cx))
 452    }
 453
 454    pub fn language<'a>(&self, cx: &'a AppContext) -> Option<&'a Arc<Language>> {
 455        self.as_singleton().unwrap().read(cx).language()
 456    }
 457
 458    pub fn file<'a>(&self, cx: &'a AppContext) -> Option<&'a dyn File> {
 459        self.as_singleton()
 460            .and_then(|buffer| buffer.read(cx).file())
 461    }
 462
 463    pub fn is_dirty(&self, cx: &AppContext) -> bool {
 464        self.as_singleton().unwrap().read(cx).is_dirty()
 465    }
 466
 467    pub fn has_conflict(&self, cx: &AppContext) -> bool {
 468        self.as_singleton().unwrap().read(cx).has_conflict()
 469    }
 470
 471    pub fn is_parsing(&self, cx: &AppContext) -> bool {
 472        self.as_singleton().unwrap().read(cx).is_parsing()
 473    }
 474
 475    fn sync(&self, cx: &AppContext) {
 476        let mut snapshot = self.snapshot.borrow_mut();
 477        let mut excerpts_to_edit = Vec::new();
 478        let mut reparsed = false;
 479        let mut diagnostics_updated = false;
 480        for buffer_state in self.buffers.values() {
 481            let buffer = buffer_state.buffer.read(cx);
 482            let buffer_edited = buffer.version().gt(&buffer_state.last_version);
 483            let buffer_reparsed = buffer.parse_count() > buffer_state.last_parse_count;
 484            let buffer_diagnostics_updated =
 485                buffer.diagnostics_update_count() > buffer_state.last_diagnostics_update_count;
 486            if buffer_edited || buffer_reparsed || buffer_diagnostics_updated {
 487                excerpts_to_edit.extend(
 488                    buffer_state
 489                        .excerpts
 490                        .iter()
 491                        .map(|excerpt_id| (excerpt_id, buffer_state, buffer_edited)),
 492                );
 493            }
 494
 495            reparsed |= buffer_reparsed;
 496            diagnostics_updated |= buffer_diagnostics_updated;
 497        }
 498        if reparsed {
 499            snapshot.parse_count += 1;
 500        }
 501        if diagnostics_updated {
 502            snapshot.diagnostics_update_count += 1;
 503        }
 504        excerpts_to_edit.sort_unstable_by_key(|(excerpt_id, _, _)| *excerpt_id);
 505
 506        let mut edits = Vec::new();
 507        let mut new_excerpts = SumTree::new();
 508        let mut cursor = snapshot.excerpts.cursor::<(Option<&ExcerptId>, usize)>();
 509
 510        for (id, buffer_state, buffer_edited) in excerpts_to_edit {
 511            new_excerpts.push_tree(cursor.slice(&Some(id), Bias::Left, &()), &());
 512            let old_excerpt = cursor.item().unwrap();
 513            let buffer = buffer_state.buffer.read(cx);
 514
 515            let mut new_excerpt;
 516            if buffer_edited {
 517                edits.extend(
 518                    buffer
 519                        .edits_since_in_range::<usize>(
 520                            old_excerpt.buffer.version(),
 521                            old_excerpt.range.clone(),
 522                        )
 523                        .map(|mut edit| {
 524                            let excerpt_old_start =
 525                                cursor.start().1 + old_excerpt.header_height as usize;
 526                            let excerpt_new_start = new_excerpts.summary().text.bytes
 527                                + old_excerpt.header_height as usize;
 528                            edit.old.start += excerpt_old_start;
 529                            edit.old.end += excerpt_old_start;
 530                            edit.new.start += excerpt_new_start;
 531                            edit.new.end += excerpt_new_start;
 532                            edit
 533                        }),
 534                );
 535
 536                new_excerpt = Excerpt::new(
 537                    id.clone(),
 538                    buffer_state.buffer.id(),
 539                    buffer.snapshot(),
 540                    old_excerpt.range.clone(),
 541                    old_excerpt.header_height,
 542                    !self.singleton,
 543                );
 544            } else {
 545                new_excerpt = old_excerpt.clone();
 546                new_excerpt.buffer = buffer.snapshot();
 547            }
 548
 549            new_excerpts.push(new_excerpt, &());
 550            cursor.next(&());
 551        }
 552        new_excerpts.push_tree(cursor.suffix(&()), &());
 553
 554        drop(cursor);
 555        snapshot.excerpts = new_excerpts;
 556
 557        self.subscriptions.publish(edits);
 558    }
 559}
 560
 561#[cfg(any(test, feature = "test-support"))]
 562impl MultiBuffer {
 563    pub fn randomly_edit<R: rand::Rng>(
 564        &mut self,
 565        rng: &mut R,
 566        count: usize,
 567        cx: &mut ModelContext<Self>,
 568    ) {
 569        self.as_singleton()
 570            .unwrap()
 571            .update(cx, |buffer, cx| buffer.randomly_edit(rng, count, cx));
 572        self.sync(cx);
 573    }
 574}
 575
 576impl Entity for MultiBuffer {
 577    type Event = language::Event;
 578}
 579
 580impl MultiBufferSnapshot {
 581    pub fn text(&self) -> String {
 582        self.chunks(0..self.len(), None)
 583            .map(|chunk| chunk.text)
 584            .collect()
 585    }
 586
 587    pub fn reversed_chars_at<'a, T: ToOffset>(
 588        &'a self,
 589        position: T,
 590    ) -> impl Iterator<Item = char> + 'a {
 591        // TODO
 592        let offset = position.to_offset(self);
 593        self.as_singleton().unwrap().reversed_chars_at(offset)
 594    }
 595
 596    pub fn chars_at<'a, T: ToOffset>(&'a self, position: T) -> impl Iterator<Item = char> + 'a {
 597        let offset = position.to_offset(self);
 598        self.text_for_range(offset..self.len())
 599            .flat_map(|chunk| chunk.chars())
 600    }
 601
 602    pub fn text_for_range<'a, T: ToOffset>(
 603        &'a self,
 604        range: Range<T>,
 605    ) -> impl Iterator<Item = &'a str> {
 606        self.chunks(range, None).map(|chunk| chunk.text)
 607    }
 608
 609    pub fn is_line_blank(&self, row: u32) -> bool {
 610        self.text_for_range(Point::new(row, 0)..Point::new(row, self.line_len(row)))
 611            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
 612    }
 613
 614    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
 615    where
 616        T: ToOffset,
 617    {
 618        let offset = position.to_offset(self);
 619        self.as_singleton().unwrap().contains_str_at(offset, needle)
 620    }
 621
 622    fn as_singleton(&self) -> Option<&BufferSnapshot> {
 623        let mut excerpts = self.excerpts.iter();
 624        let buffer = excerpts.next().map(|excerpt| &excerpt.buffer);
 625        if excerpts.next().is_none() {
 626            buffer
 627        } else {
 628            None
 629        }
 630    }
 631
 632    pub fn len(&self) -> usize {
 633        self.excerpts.summary().text.bytes
 634    }
 635
 636    pub fn clip_offset(&self, offset: usize, bias: Bias) -> usize {
 637        let mut cursor = self.excerpts.cursor::<usize>();
 638        cursor.seek(&offset, Bias::Right, &());
 639        if let Some(excerpt) = cursor.item() {
 640            let start_after_header = *cursor.start() + excerpt.header_height as usize;
 641            if offset < start_after_header {
 642                *cursor.start()
 643            } else {
 644                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 645                let buffer_offset = excerpt
 646                    .buffer
 647                    .clip_offset(excerpt_start + (offset - start_after_header), bias);
 648                let offset_in_excerpt = if buffer_offset > excerpt_start {
 649                    buffer_offset - excerpt_start
 650                } else {
 651                    0
 652                };
 653                start_after_header + offset_in_excerpt
 654            }
 655        } else {
 656            self.excerpts.summary().text.bytes
 657        }
 658    }
 659
 660    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
 661        let mut cursor = self.excerpts.cursor::<Point>();
 662        cursor.seek(&point, Bias::Right, &());
 663        if let Some(excerpt) = cursor.item() {
 664            let start_after_header = *cursor.start() + Point::new(excerpt.header_height as u32, 0);
 665            if point < start_after_header {
 666                *cursor.start()
 667            } else {
 668                let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
 669                let buffer_point = excerpt
 670                    .buffer
 671                    .clip_point(excerpt_start + (point - start_after_header), bias);
 672                let point_in_excerpt = if buffer_point > excerpt_start {
 673                    buffer_point - excerpt_start
 674                } else {
 675                    Point::zero()
 676                };
 677                start_after_header + point_in_excerpt
 678            }
 679        } else {
 680            self.excerpts.summary().text.lines
 681        }
 682    }
 683
 684    pub fn clip_point_utf16(&self, point: PointUtf16, bias: Bias) -> PointUtf16 {
 685        let mut cursor = self.excerpts.cursor::<PointUtf16>();
 686        cursor.seek(&point, Bias::Right, &());
 687        if let Some(excerpt) = cursor.item() {
 688            let start_after_header =
 689                *cursor.start() + PointUtf16::new(excerpt.header_height as u32, 0);
 690            if point < start_after_header {
 691                *cursor.start()
 692            } else {
 693                let excerpt_start = excerpt
 694                    .buffer
 695                    .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
 696                let buffer_point = excerpt
 697                    .buffer
 698                    .clip_point_utf16(excerpt_start + (point - start_after_header), bias);
 699                let point_in_excerpt = if buffer_point > excerpt_start {
 700                    buffer_point - excerpt_start
 701                } else {
 702                    PointUtf16::new(0, 0)
 703                };
 704                start_after_header + point_in_excerpt
 705            }
 706        } else {
 707            self.excerpts.summary().text.lines_utf16
 708        }
 709    }
 710
 711    pub fn bytes_in_range<'a, T: ToOffset>(&'a self, range: Range<T>) -> MultiBufferBytes<'a> {
 712        MultiBufferBytes {
 713            chunks: self.chunks(range, None).peekable(),
 714        }
 715    }
 716
 717    pub fn chunks<'a, T: ToOffset>(
 718        &'a self,
 719        range: Range<T>,
 720        theme: Option<&'a SyntaxTheme>,
 721    ) -> MultiBufferChunks<'a> {
 722        let mut result = MultiBufferChunks {
 723            range: 0..range.end.to_offset(self),
 724            cursor: self.excerpts.cursor::<usize>(),
 725            header_height: 0,
 726            excerpt_chunks: None,
 727            has_trailing_newline: false,
 728            theme,
 729        };
 730        result.seek(range.start.to_offset(self));
 731        result
 732    }
 733
 734    pub fn offset_to_point(&self, offset: usize) -> Point {
 735        let mut cursor = self.excerpts.cursor::<(usize, Point)>();
 736        cursor.seek(&offset, Bias::Right, &());
 737        if let Some(excerpt) = cursor.item() {
 738            let (start_offset, start_point) = cursor.start();
 739            let overshoot = offset - start_offset;
 740            let header_height = excerpt.header_height as usize;
 741            if overshoot < header_height {
 742                *start_point
 743            } else {
 744                let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
 745                let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
 746                let buffer_point = excerpt
 747                    .buffer
 748                    .offset_to_point(excerpt_start_offset + (overshoot - header_height));
 749                *start_point
 750                    + Point::new(header_height as u32, 0)
 751                    + (buffer_point - excerpt_start_point)
 752            }
 753        } else {
 754            self.excerpts.summary().text.lines
 755        }
 756    }
 757
 758    pub fn point_to_offset(&self, point: Point) -> usize {
 759        let mut cursor = self.excerpts.cursor::<(Point, usize)>();
 760        cursor.seek(&point, Bias::Right, &());
 761        if let Some(excerpt) = cursor.item() {
 762            let (start_point, start_offset) = cursor.start();
 763            let overshoot = point - start_point;
 764            let header_height = Point::new(excerpt.header_height as u32, 0);
 765            if overshoot < header_height {
 766                *start_offset
 767            } else {
 768                let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
 769                let excerpt_start_point = excerpt.range.start.to_point(&excerpt.buffer);
 770                let buffer_offset = excerpt
 771                    .buffer
 772                    .point_to_offset(excerpt_start_point + (overshoot - header_height));
 773                *start_offset + excerpt.header_height as usize + buffer_offset
 774                    - excerpt_start_offset
 775            }
 776        } else {
 777            self.excerpts.summary().text.bytes
 778        }
 779    }
 780
 781    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> usize {
 782        let mut cursor = self.excerpts.cursor::<(PointUtf16, usize)>();
 783        cursor.seek(&point, Bias::Right, &());
 784        if let Some(excerpt) = cursor.item() {
 785            let (start_point, start_offset) = cursor.start();
 786            let overshoot = point - start_point;
 787            let header_height = PointUtf16::new(excerpt.header_height as u32, 0);
 788            if overshoot < header_height {
 789                *start_offset
 790            } else {
 791                let excerpt_start_offset = excerpt.range.start.to_offset(&excerpt.buffer);
 792                let excerpt_start_point = excerpt
 793                    .buffer
 794                    .offset_to_point_utf16(excerpt.range.start.to_offset(&excerpt.buffer));
 795                let buffer_offset = excerpt
 796                    .buffer
 797                    .point_utf16_to_offset(excerpt_start_point + (overshoot - header_height));
 798                *start_offset
 799                    + excerpt.header_height as usize
 800                    + (buffer_offset - excerpt_start_offset)
 801            }
 802        } else {
 803            self.excerpts.summary().text.bytes
 804        }
 805    }
 806
 807    pub fn indent_column_for_line(&self, row: u32) -> u32 {
 808        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
 809            buffer
 810                .indent_column_for_line(range.start.row)
 811                .min(range.end.column)
 812                .saturating_sub(range.start.column)
 813        } else {
 814            0
 815        }
 816    }
 817
 818    pub fn line_len(&self, row: u32) -> u32 {
 819        if let Some((_, range)) = self.buffer_line_for_row(row) {
 820            range.end.column - range.start.column
 821        } else {
 822            0
 823        }
 824    }
 825
 826    fn buffer_line_for_row(&self, row: u32) -> Option<(&BufferSnapshot, Range<Point>)> {
 827        let mut cursor = self.excerpts.cursor::<Point>();
 828        cursor.seek(&Point::new(row, 0), Bias::Right, &());
 829        if let Some(excerpt) = cursor.item() {
 830            let overshoot = row - cursor.start().row;
 831            let header_height = excerpt.header_height as u32;
 832            if overshoot >= header_height {
 833                let excerpt_start = excerpt.range.start.to_point(&excerpt.buffer);
 834                let excerpt_end = excerpt.range.end.to_point(&excerpt.buffer);
 835                let buffer_row = excerpt_start.row + overshoot - header_height;
 836                let line_start = Point::new(buffer_row, 0);
 837                let line_end = Point::new(buffer_row, excerpt.buffer.line_len(buffer_row));
 838                return Some((
 839                    &excerpt.buffer,
 840                    line_start.max(excerpt_start)..line_end.min(excerpt_end),
 841                ));
 842            }
 843        }
 844        None
 845    }
 846
 847    pub fn max_point(&self) -> Point {
 848        self.text_summary().lines
 849    }
 850
 851    pub fn text_summary(&self) -> TextSummary {
 852        self.excerpts.summary().text
 853    }
 854
 855    pub fn text_summary_for_range<'a, D, O>(&'a self, range: Range<O>) -> D
 856    where
 857        D: TextDimension,
 858        O: ToOffset,
 859    {
 860        let mut summary = D::default();
 861        let mut range = range.start.to_offset(self)..range.end.to_offset(self);
 862        let mut cursor = self.excerpts.cursor::<usize>();
 863        cursor.seek(&range.start, Bias::Right, &());
 864        if let Some(excerpt) = cursor.item() {
 865            let start_after_header = cursor.start() + excerpt.header_height as usize;
 866            if range.start < start_after_header {
 867                let header_len = cmp::min(range.end, start_after_header) - range.start;
 868                summary.add_assign(&D::from_text_summary(&TextSummary {
 869                    bytes: header_len,
 870                    lines: Point::new(header_len as u32, 0),
 871                    lines_utf16: PointUtf16::new(header_len as u32, 0),
 872                    first_line_chars: 0,
 873                    last_line_chars: 0,
 874                    longest_row: 0,
 875                    longest_row_chars: 0,
 876                }));
 877                range.start = start_after_header;
 878                range.end = cmp::max(range.start, range.end);
 879            }
 880
 881            let mut end_before_newline = cursor.end(&());
 882            if excerpt.has_trailing_newline {
 883                end_before_newline -= 1;
 884            }
 885
 886            let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 887            let start_in_excerpt = excerpt_start + (range.start - start_after_header);
 888            let end_in_excerpt =
 889                excerpt_start + (cmp::min(end_before_newline, range.end) - start_after_header);
 890            summary.add_assign(
 891                &excerpt
 892                    .buffer
 893                    .text_summary_for_range(start_in_excerpt..end_in_excerpt),
 894            );
 895
 896            if range.end > end_before_newline {
 897                summary.add_assign(&D::from_text_summary(&TextSummary {
 898                    bytes: 1,
 899                    lines: Point::new(1 as u32, 0),
 900                    lines_utf16: PointUtf16::new(1 as u32, 0),
 901                    first_line_chars: 0,
 902                    last_line_chars: 0,
 903                    longest_row: 0,
 904                    longest_row_chars: 0,
 905                }));
 906            }
 907
 908            cursor.next(&());
 909        }
 910
 911        if range.end > *cursor.start() {
 912            summary.add_assign(&D::from_text_summary(&cursor.summary::<_, TextSummary>(
 913                &range.end,
 914                Bias::Right,
 915                &(),
 916            )));
 917            if let Some(excerpt) = cursor.item() {
 918                let start_after_header = cursor.start() + excerpt.header_height as usize;
 919                let header_len =
 920                    cmp::min(range.end - cursor.start(), excerpt.header_height as usize);
 921                summary.add_assign(&D::from_text_summary(&TextSummary {
 922                    bytes: header_len,
 923                    lines: Point::new(header_len as u32, 0),
 924                    lines_utf16: PointUtf16::new(header_len as u32, 0),
 925                    first_line_chars: 0,
 926                    last_line_chars: 0,
 927                    longest_row: 0,
 928                    longest_row_chars: 0,
 929                }));
 930                range.end = cmp::max(start_after_header, range.end);
 931
 932                let excerpt_start = excerpt.range.start.to_offset(&excerpt.buffer);
 933                let end_in_excerpt = excerpt_start + (range.end - start_after_header);
 934                summary.add_assign(
 935                    &excerpt
 936                        .buffer
 937                        .text_summary_for_range(excerpt_start..end_in_excerpt),
 938                );
 939                cursor.next(&());
 940            }
 941        }
 942
 943        summary
 944    }
 945
 946    pub fn summary_for_anchor<D>(&self, anchor: &Anchor) -> D
 947    where
 948        D: TextDimension + Ord + Sub<D, Output = D>,
 949    {
 950        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
 951        cursor.seek(&Some(&anchor.excerpt_id), Bias::Left, &());
 952        if let Some(excerpt) = cursor.item() {
 953            if excerpt.id == anchor.excerpt_id {
 954                let mut excerpt_start = D::from_text_summary(&cursor.start().text);
 955                excerpt_start.add_summary(&excerpt.header_summary(), &());
 956                let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
 957                let buffer_point = anchor.text_anchor.summary::<D>(&excerpt.buffer);
 958                if buffer_point > excerpt_buffer_start {
 959                    excerpt_start.add_assign(&(buffer_point - excerpt_buffer_start));
 960                }
 961                return excerpt_start;
 962            }
 963        }
 964        D::from_text_summary(&cursor.start().text)
 965    }
 966
 967    pub fn summaries_for_anchors<'a, D, I>(&'a self, anchors: I) -> Vec<D>
 968    where
 969        D: TextDimension + Ord + Sub<D, Output = D>,
 970        I: 'a + IntoIterator<Item = &'a Anchor>,
 971    {
 972        let mut anchors = anchors.into_iter().peekable();
 973        let mut cursor = self.excerpts.cursor::<ExcerptSummary>();
 974        let mut summaries = Vec::new();
 975        while let Some(anchor) = anchors.peek() {
 976            let excerpt_id = &anchor.excerpt_id;
 977            let excerpt_anchors = std::iter::from_fn(|| {
 978                let anchor = anchors.peek()?;
 979                if anchor.excerpt_id == *excerpt_id {
 980                    Some(&anchors.next().unwrap().text_anchor)
 981                } else {
 982                    None
 983                }
 984            });
 985
 986            cursor.seek_forward(&Some(excerpt_id), Bias::Left, &());
 987            if let Some(excerpt) = cursor.item() {
 988                if excerpt.id == *excerpt_id {
 989                    let mut excerpt_start = D::from_text_summary(&cursor.start().text);
 990                    excerpt_start.add_summary(&excerpt.header_summary(), &());
 991                    let excerpt_buffer_start = excerpt.range.start.summary::<D>(&excerpt.buffer);
 992                    summaries.extend(
 993                        excerpt
 994                            .buffer
 995                            .summaries_for_anchors::<D, _>(excerpt_anchors)
 996                            .map(move |summary| {
 997                                let mut excerpt_start = excerpt_start.clone();
 998                                let excerpt_buffer_start = excerpt_buffer_start.clone();
 999                                if summary > excerpt_buffer_start {
1000                                    excerpt_start.add_assign(&(summary - excerpt_buffer_start));
1001                                }
1002                                excerpt_start
1003                            }),
1004                    );
1005                    continue;
1006                }
1007            }
1008
1009            let summary = D::from_text_summary(&cursor.start().text);
1010            summaries.extend(excerpt_anchors.map(|_| summary.clone()));
1011        }
1012
1013        summaries
1014    }
1015
1016    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
1017        self.anchor_at(position, Bias::Left)
1018    }
1019
1020    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
1021        self.anchor_at(position, Bias::Right)
1022    }
1023
1024    pub fn anchor_at<T: ToOffset>(&self, position: T, bias: Bias) -> Anchor {
1025        let offset = position.to_offset(self);
1026        let mut cursor = self.excerpts.cursor::<(usize, Option<&ExcerptId>)>();
1027        cursor.seek(&offset, bias, &());
1028        if let Some(excerpt) = cursor.item() {
1029            let overshoot =
1030                (offset - cursor.start().0).saturating_sub(excerpt.header_height as usize);
1031            let buffer_start = excerpt.range.start.to_offset(&excerpt.buffer);
1032            Anchor {
1033                excerpt_id: excerpt.id.clone(),
1034                text_anchor: excerpt.buffer.anchor_at(buffer_start + overshoot, bias),
1035            }
1036        } else if offset == 0 && bias == Bias::Left {
1037            Anchor::min()
1038        } else {
1039            Anchor::max()
1040        }
1041    }
1042
1043    pub fn parse_count(&self) -> usize {
1044        self.parse_count
1045    }
1046
1047    pub fn enclosing_bracket_ranges<T: ToOffset>(
1048        &self,
1049        range: Range<T>,
1050    ) -> Option<(Range<usize>, Range<usize>)> {
1051        let range = range.start.to_offset(self)..range.end.to_offset(self);
1052        self.as_singleton().unwrap().enclosing_bracket_ranges(range)
1053    }
1054
1055    pub fn diagnostics_update_count(&self) -> usize {
1056        self.diagnostics_update_count
1057    }
1058
1059    pub fn language(&self) -> Option<&Arc<Language>> {
1060        self.as_singleton().unwrap().language()
1061    }
1062
1063    pub fn diagnostic_group<'a, O>(
1064        &'a self,
1065        group_id: usize,
1066    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1067    where
1068        O: text::FromAnchor + 'a,
1069    {
1070        self.as_singleton().unwrap().diagnostic_group(group_id)
1071    }
1072
1073    pub fn diagnostics_in_range<'a, T, O>(
1074        &'a self,
1075        range: Range<T>,
1076    ) -> impl Iterator<Item = DiagnosticEntry<O>> + 'a
1077    where
1078        T: 'a + ToOffset,
1079        O: 'a + text::FromAnchor,
1080    {
1081        let range = range.start.to_offset(self)..range.end.to_offset(self);
1082        self.as_singleton().unwrap().diagnostics_in_range(range)
1083    }
1084
1085    pub fn range_for_syntax_ancestor<T: ToOffset>(&self, range: Range<T>) -> Option<Range<usize>> {
1086        let range = range.start.to_offset(self)..range.end.to_offset(self);
1087        self.as_singleton()
1088            .unwrap()
1089            .range_for_syntax_ancestor(range)
1090    }
1091
1092    fn buffer_snapshot_for_excerpt<'a>(
1093        &'a self,
1094        excerpt_id: &'a ExcerptId,
1095    ) -> Option<&'a BufferSnapshot> {
1096        let mut cursor = self.excerpts.cursor::<Option<&ExcerptId>>();
1097        cursor.seek(&Some(excerpt_id), Bias::Left, &());
1098        if let Some(excerpt) = cursor.item() {
1099            if excerpt.id == *excerpt_id {
1100                return Some(&excerpt.buffer);
1101            }
1102        }
1103        None
1104    }
1105
1106    pub fn remote_selections_in_range<'a>(
1107        &'a self,
1108        range: Range<Anchor>,
1109    ) -> impl 'a + Iterator<Item = (ReplicaId, impl 'a + Iterator<Item = Selection<Anchor>>)> {
1110        // TODO
1111        let excerpt_id = self.excerpts.first().unwrap().id.clone();
1112        self.as_singleton()
1113            .unwrap()
1114            .remote_selections_in_range(range.start.text_anchor..range.end.text_anchor)
1115            .map(move |(replica_id, selections)| {
1116                let excerpt_id = excerpt_id.clone();
1117                (
1118                    replica_id,
1119                    selections.map(move |s| Selection {
1120                        id: s.id,
1121                        start: Anchor {
1122                            excerpt_id: excerpt_id.clone(),
1123                            text_anchor: s.start.clone(),
1124                        },
1125                        end: Anchor {
1126                            excerpt_id: excerpt_id.clone(),
1127                            text_anchor: s.end.clone(),
1128                        },
1129                        reversed: s.reversed,
1130                        goal: s.goal,
1131                    }),
1132                )
1133            })
1134    }
1135}
1136
1137impl Excerpt {
1138    fn new(
1139        id: ExcerptId,
1140        buffer_id: usize,
1141        buffer: BufferSnapshot,
1142        range: Range<text::Anchor>,
1143        header_height: u8,
1144        has_trailing_newline: bool,
1145    ) -> Self {
1146        let mut text_summary =
1147            buffer.text_summary_for_range::<TextSummary, _>(range.to_offset(&buffer));
1148        if header_height > 0 {
1149            text_summary.first_line_chars = 0;
1150            text_summary.lines.row += header_height as u32;
1151            text_summary.lines_utf16.row += header_height as u32;
1152            text_summary.bytes += header_height as usize;
1153            text_summary.longest_row += header_height as u32;
1154        }
1155        if has_trailing_newline {
1156            text_summary.last_line_chars = 0;
1157            text_summary.lines.row += 1;
1158            text_summary.lines.column = 0;
1159            text_summary.lines_utf16.row += 1;
1160            text_summary.lines_utf16.column = 0;
1161            text_summary.bytes += 1;
1162        }
1163
1164        Excerpt {
1165            id,
1166            buffer_id,
1167            buffer,
1168            range,
1169            text_summary,
1170            header_height,
1171            has_trailing_newline,
1172        }
1173    }
1174
1175    fn header_summary(&self) -> TextSummary {
1176        TextSummary {
1177            bytes: self.header_height as usize,
1178            lines: Point::new(self.header_height as u32, 0),
1179            lines_utf16: PointUtf16::new(self.header_height as u32, 0),
1180            first_line_chars: 0,
1181            last_line_chars: 0,
1182            longest_row: 0,
1183            longest_row_chars: 0,
1184        }
1185    }
1186}
1187
1188impl sum_tree::Item for Excerpt {
1189    type Summary = ExcerptSummary;
1190
1191    fn summary(&self) -> Self::Summary {
1192        ExcerptSummary {
1193            excerpt_id: self.id.clone(),
1194            text: self.text_summary.clone(),
1195        }
1196    }
1197}
1198
1199impl sum_tree::Summary for ExcerptSummary {
1200    type Context = ();
1201
1202    fn add_summary(&mut self, summary: &Self, _: &()) {
1203        debug_assert!(summary.excerpt_id > self.excerpt_id);
1204        self.excerpt_id = summary.excerpt_id.clone();
1205        self.text.add_summary(&summary.text, &());
1206    }
1207}
1208
1209impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for TextSummary {
1210    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1211        *self += &summary.text;
1212    }
1213}
1214
1215impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for usize {
1216    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1217        *self += summary.text.bytes;
1218    }
1219}
1220
1221impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for usize {
1222    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
1223        Ord::cmp(self, &cursor_location.text.bytes)
1224    }
1225}
1226
1227impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, ExcerptSummary> for Option<&'a ExcerptId> {
1228    fn cmp(&self, cursor_location: &ExcerptSummary, _: &()) -> cmp::Ordering {
1229        Ord::cmp(self, &Some(&cursor_location.excerpt_id))
1230    }
1231}
1232
1233impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Point {
1234    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1235        *self += summary.text.lines;
1236    }
1237}
1238
1239impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for PointUtf16 {
1240    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1241        *self += summary.text.lines_utf16
1242    }
1243}
1244
1245impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a ExcerptId> {
1246    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: &()) {
1247        *self = Some(&summary.excerpt_id);
1248    }
1249}
1250
1251impl<'a> MultiBufferChunks<'a> {
1252    pub fn offset(&self) -> usize {
1253        self.range.start
1254    }
1255
1256    pub fn seek(&mut self, offset: usize) {
1257        self.range.start = offset;
1258        self.cursor.seek_forward(&offset, Bias::Right, &());
1259        self.header_height = 0;
1260        self.excerpt_chunks = None;
1261        if let Some(excerpt) = self.cursor.item() {
1262            let buffer_range = excerpt.range.to_offset(&excerpt.buffer);
1263            self.header_height = excerpt.header_height;
1264            self.has_trailing_newline = excerpt.has_trailing_newline;
1265
1266            let buffer_start;
1267            let start_overshoot = self.range.start - self.cursor.start();
1268            if start_overshoot < excerpt.header_height as usize {
1269                self.header_height -= start_overshoot as u8;
1270                buffer_start = buffer_range.start;
1271            } else {
1272                buffer_start =
1273                    buffer_range.start + start_overshoot - excerpt.header_height as usize;
1274                self.header_height = 0;
1275            }
1276
1277            let buffer_end;
1278            let end_overshoot = self.range.end - self.cursor.start();
1279            if end_overshoot < excerpt.header_height as usize {
1280                self.header_height -= excerpt.header_height - end_overshoot as u8;
1281                buffer_end = buffer_start;
1282            } else {
1283                buffer_end = cmp::min(
1284                    buffer_range.end,
1285                    buffer_range.start + end_overshoot - excerpt.header_height as usize,
1286                );
1287            }
1288
1289            self.excerpt_chunks = Some(excerpt.buffer.chunks(buffer_start..buffer_end, self.theme));
1290        }
1291    }
1292}
1293
1294impl<'a> Iterator for MultiBufferChunks<'a> {
1295    type Item = Chunk<'a>;
1296
1297    fn next(&mut self) -> Option<Self::Item> {
1298        loop {
1299            if self.header_height > 0 {
1300                let chunk = Chunk {
1301                    text: unsafe {
1302                        std::str::from_utf8_unchecked(&NEWLINES[..self.header_height as usize])
1303                    },
1304                    ..Default::default()
1305                };
1306                self.range.start += self.header_height as usize;
1307                self.header_height = 0;
1308                return Some(chunk);
1309            }
1310
1311            if let Some(excerpt_chunks) = self.excerpt_chunks.as_mut() {
1312                if let Some(chunk) = excerpt_chunks.next() {
1313                    self.range.start += chunk.text.len();
1314                    return Some(chunk);
1315                }
1316                self.excerpt_chunks.take();
1317                if self.has_trailing_newline && self.cursor.end(&()) <= self.range.end {
1318                    self.range.start += 1;
1319                    return Some(Chunk {
1320                        text: "\n",
1321                        ..Default::default()
1322                    });
1323                }
1324            }
1325
1326            self.cursor.next(&());
1327            if *self.cursor.start() >= self.range.end {
1328                return None;
1329            }
1330
1331            let excerpt = self.cursor.item()?;
1332            let buffer_range = excerpt.range.to_offset(&excerpt.buffer);
1333
1334            let buffer_end = cmp::min(
1335                buffer_range.end,
1336                buffer_range.start + self.range.end
1337                    - excerpt.header_height as usize
1338                    - self.cursor.start(),
1339            );
1340
1341            self.header_height = excerpt.header_height;
1342            self.has_trailing_newline = excerpt.has_trailing_newline;
1343            self.excerpt_chunks = Some(
1344                excerpt
1345                    .buffer
1346                    .chunks(buffer_range.start..buffer_end, self.theme),
1347            );
1348        }
1349    }
1350}
1351
1352impl<'a> Iterator for MultiBufferBytes<'a> {
1353    type Item = &'a [u8];
1354
1355    fn next(&mut self) -> Option<Self::Item> {
1356        self.chunks.next().map(|chunk| chunk.text.as_bytes())
1357    }
1358}
1359
1360impl<'a> io::Read for MultiBufferBytes<'a> {
1361    fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
1362        todo!()
1363    }
1364}
1365
1366impl ToOffset for Point {
1367    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
1368        snapshot.point_to_offset(*self)
1369    }
1370}
1371
1372impl ToOffset for PointUtf16 {
1373    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
1374        snapshot.point_utf16_to_offset(*self)
1375    }
1376}
1377
1378impl ToOffset for usize {
1379    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> usize {
1380        assert!(*self <= snapshot.len(), "offset is out of range");
1381        *self
1382    }
1383}
1384
1385impl ToPoint for usize {
1386    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
1387        snapshot.offset_to_point(*self)
1388    }
1389}
1390
1391impl ToPoint for Point {
1392    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
1393        *self
1394    }
1395}
1396
1397#[cfg(test)]
1398mod tests {
1399    use super::*;
1400    use gpui::MutableAppContext;
1401    use language::Buffer;
1402    use rand::prelude::*;
1403    use std::env;
1404    use text::{Point, RandomCharIter};
1405    use util::test::sample_text;
1406
1407    #[gpui::test]
1408    fn test_singleton_multibuffer(cx: &mut MutableAppContext) {
1409        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
1410        let multibuffer = cx.add_model(|cx| MultiBuffer::singleton(buffer.clone(), cx));
1411        assert_eq!(
1412            multibuffer.read(cx).snapshot(cx).text(),
1413            buffer.read(cx).text()
1414        );
1415
1416        buffer.update(cx, |buffer, cx| buffer.edit([1..3], "XXX", cx));
1417        assert_eq!(
1418            multibuffer.read(cx).snapshot(cx).text(),
1419            buffer.read(cx).text()
1420        );
1421    }
1422
1423    #[gpui::test]
1424    fn test_excerpt_buffer(cx: &mut MutableAppContext) {
1425        let buffer_1 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'a'), cx));
1426        let buffer_2 = cx.add_model(|cx| Buffer::new(0, sample_text(6, 6, 'g'), cx));
1427
1428        let multibuffer = cx.add_model(|_| MultiBuffer::new(0));
1429
1430        let subscription = multibuffer.update(cx, |multibuffer, cx| {
1431            let subscription = multibuffer.subscribe();
1432            multibuffer.push_excerpt(
1433                ExcerptProperties {
1434                    buffer: &buffer_1,
1435                    range: Point::new(1, 2)..Point::new(2, 5),
1436                    header_height: 2,
1437                },
1438                cx,
1439            );
1440            assert_eq!(
1441                subscription.consume().into_inner(),
1442                [Edit {
1443                    old: 0..0,
1444                    new: 0..13
1445                }]
1446            );
1447
1448            multibuffer.push_excerpt(
1449                ExcerptProperties {
1450                    buffer: &buffer_1,
1451                    range: Point::new(3, 3)..Point::new(4, 4),
1452                    header_height: 1,
1453                },
1454                cx,
1455            );
1456            multibuffer.push_excerpt(
1457                ExcerptProperties {
1458                    buffer: &buffer_2,
1459                    range: Point::new(3, 1)..Point::new(3, 3),
1460                    header_height: 3,
1461                },
1462                cx,
1463            );
1464            assert_eq!(
1465                subscription.consume().into_inner(),
1466                [Edit {
1467                    old: 13..13,
1468                    new: 13..29
1469                }]
1470            );
1471
1472            subscription
1473        });
1474
1475        assert_eq!(
1476            multibuffer.read(cx).snapshot(cx).text(),
1477            concat!(
1478                "\n",      // Preserve newlines
1479                "\n",      //
1480                "bbbb\n",  //
1481                "ccccc\n", //
1482                "\n",      //
1483                "ddd\n",   //
1484                "eeee\n",  //
1485                "\n",      //
1486                "\n",      //
1487                "\n",      //
1488                "jj\n"     //
1489            )
1490        );
1491
1492        buffer_1.update(cx, |buffer, cx| {
1493            buffer.edit(
1494                [
1495                    Point::new(0, 0)..Point::new(0, 0),
1496                    Point::new(2, 1)..Point::new(2, 3),
1497                ],
1498                "\n",
1499                cx,
1500            );
1501        });
1502
1503        assert_eq!(
1504            multibuffer.read(cx).snapshot(cx).text(),
1505            concat!(
1506                "\n",     // Preserve newlines
1507                "\n",     //
1508                "bbbb\n", //
1509                "c\n",    //
1510                "cc\n",   //
1511                "\n",     //
1512                "ddd\n",  //
1513                "eeee\n", //
1514                "\n",     //
1515                "\n",     //
1516                "\n",     //
1517                "jj\n"    //
1518            )
1519        );
1520
1521        assert_eq!(
1522            subscription.consume().into_inner(),
1523            [Edit {
1524                old: 8..10,
1525                new: 8..9
1526            }]
1527        );
1528    }
1529
1530    #[gpui::test(iterations = 100)]
1531    fn test_random_excerpts(cx: &mut MutableAppContext, mut rng: StdRng) {
1532        let operations = env::var("OPERATIONS")
1533            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1534            .unwrap_or(10);
1535
1536        let mut buffers: Vec<ModelHandle<Buffer>> = Vec::new();
1537        let list = cx.add_model(|_| MultiBuffer::new(0));
1538        let mut excerpt_ids = Vec::new();
1539        let mut expected_excerpts = Vec::new();
1540        let mut old_versions = Vec::new();
1541
1542        for _ in 0..operations {
1543            match rng.gen_range(0..100) {
1544                0..=19 if !buffers.is_empty() => {
1545                    let buffer = buffers.choose(&mut rng).unwrap();
1546                    buffer.update(cx, |buf, cx| buf.randomly_edit(&mut rng, 1, cx));
1547                }
1548                _ => {
1549                    let buffer_handle = if buffers.is_empty() || rng.gen_bool(0.4) {
1550                        let base_text = RandomCharIter::new(&mut rng).take(10).collect::<String>();
1551                        buffers.push(cx.add_model(|cx| Buffer::new(0, base_text, cx)));
1552                        buffers.last().unwrap()
1553                    } else {
1554                        buffers.choose(&mut rng).unwrap()
1555                    };
1556
1557                    let buffer = buffer_handle.read(cx);
1558                    let end_ix = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Bias::Right);
1559                    let start_ix = buffer.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1560                    let header_height = rng.gen_range(0..=5);
1561                    let anchor_range = buffer.anchor_before(start_ix)..buffer.anchor_after(end_ix);
1562                    log::info!(
1563                        "Pushing excerpt wih header {}, buffer {}: {:?}[{:?}] = {:?}",
1564                        header_height,
1565                        buffer_handle.id(),
1566                        buffer.text(),
1567                        start_ix..end_ix,
1568                        &buffer.text()[start_ix..end_ix]
1569                    );
1570
1571                    let excerpt_id = list.update(cx, |list, cx| {
1572                        list.push_excerpt(
1573                            ExcerptProperties {
1574                                buffer: &buffer_handle,
1575                                range: start_ix..end_ix,
1576                                header_height,
1577                            },
1578                            cx,
1579                        )
1580                    });
1581                    excerpt_ids.push(excerpt_id);
1582                    expected_excerpts.push((buffer_handle.clone(), anchor_range, header_height));
1583                }
1584            }
1585
1586            if rng.gen_bool(0.3) {
1587                list.update(cx, |list, cx| {
1588                    old_versions.push((list.snapshot(cx), list.subscribe()));
1589                })
1590            }
1591
1592            let snapshot = list.read(cx).snapshot(cx);
1593
1594            let mut excerpt_starts = Vec::new();
1595            let mut expected_text = String::new();
1596            for (buffer, range, header_height) in &expected_excerpts {
1597                let buffer = buffer.read(cx);
1598                let buffer_range = range.to_offset(buffer);
1599
1600                for _ in 0..*header_height {
1601                    expected_text.push('\n');
1602                }
1603
1604                excerpt_starts.push(TextSummary::from(expected_text.as_str()));
1605                expected_text.extend(buffer.text_for_range(buffer_range.clone()));
1606                expected_text.push('\n');
1607            }
1608
1609            assert_eq!(snapshot.text(), expected_text);
1610
1611            let mut excerpt_starts = excerpt_starts.into_iter();
1612            for (buffer, range, _) in &expected_excerpts {
1613                let buffer_id = buffer.id();
1614                let buffer = buffer.read(cx);
1615                let buffer_range = range.to_offset(buffer);
1616                let buffer_start_point = buffer.offset_to_point(buffer_range.start);
1617                let buffer_start_point_utf16 =
1618                    buffer.text_summary_for_range::<PointUtf16, _>(0..buffer_range.start);
1619
1620                let excerpt_start = excerpt_starts.next().unwrap();
1621                let mut offset = excerpt_start.bytes;
1622                let mut buffer_offset = buffer_range.start;
1623                let mut point = excerpt_start.lines;
1624                let mut buffer_point = buffer_start_point;
1625                let mut point_utf16 = excerpt_start.lines_utf16;
1626                let mut buffer_point_utf16 = buffer_start_point_utf16;
1627                for byte in buffer.bytes_in_range(buffer_range.clone()).flatten() {
1628                    let left_offset = snapshot.clip_offset(offset, Bias::Left);
1629                    let right_offset = snapshot.clip_offset(offset, Bias::Right);
1630                    let buffer_left_offset = buffer.clip_offset(buffer_offset, Bias::Left);
1631                    let buffer_right_offset = buffer.clip_offset(buffer_offset, Bias::Right);
1632                    assert_eq!(
1633                        left_offset,
1634                        excerpt_start.bytes + (buffer_left_offset - buffer_range.start),
1635                        "clip_offset({:?}, Left). buffer: {:?}, buffer offset: {:?}",
1636                        offset,
1637                        buffer_id,
1638                        buffer_offset,
1639                    );
1640                    assert_eq!(
1641                        right_offset,
1642                        excerpt_start.bytes + (buffer_right_offset - buffer_range.start),
1643                        "clip_offset({:?}, Right). buffer: {:?}, buffer offset: {:?}",
1644                        offset,
1645                        buffer_id,
1646                        buffer_offset,
1647                    );
1648
1649                    let left_point = snapshot.clip_point(point, Bias::Left);
1650                    let right_point = snapshot.clip_point(point, Bias::Right);
1651                    let buffer_left_point = buffer.clip_point(buffer_point, Bias::Left);
1652                    let buffer_right_point = buffer.clip_point(buffer_point, Bias::Right);
1653                    assert_eq!(
1654                        left_point,
1655                        excerpt_start.lines + (buffer_left_point - buffer_start_point),
1656                        "clip_point({:?}, Left). buffer: {:?}, buffer point: {:?}",
1657                        point,
1658                        buffer_id,
1659                        buffer_point,
1660                    );
1661                    assert_eq!(
1662                        right_point,
1663                        excerpt_start.lines + (buffer_right_point - buffer_start_point),
1664                        "clip_point({:?}, Right). buffer: {:?}, buffer point: {:?}",
1665                        point,
1666                        buffer_id,
1667                        buffer_point,
1668                    );
1669
1670                    let left_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Left);
1671                    let right_point_utf16 = snapshot.clip_point_utf16(point_utf16, Bias::Right);
1672                    let buffer_left_point_utf16 =
1673                        buffer.clip_point_utf16(buffer_point_utf16, Bias::Left);
1674                    let buffer_right_point_utf16 =
1675                        buffer.clip_point_utf16(buffer_point_utf16, Bias::Right);
1676                    assert_eq!(
1677                        left_point_utf16,
1678                        excerpt_start.lines_utf16
1679                            + (buffer_left_point_utf16 - buffer_start_point_utf16),
1680                        "clip_point_utf16({:?}, Left). buffer: {:?}, buffer point_utf16: {:?}",
1681                        point_utf16,
1682                        buffer_id,
1683                        buffer_point_utf16,
1684                    );
1685                    assert_eq!(
1686                        right_point_utf16,
1687                        excerpt_start.lines_utf16
1688                            + (buffer_right_point_utf16 - buffer_start_point_utf16),
1689                        "clip_point_utf16({:?}, Right). buffer: {:?}, buffer point_utf16: {:?}",
1690                        point_utf16,
1691                        buffer_id,
1692                        buffer_point_utf16,
1693                    );
1694
1695                    assert_eq!(
1696                        snapshot.point_to_offset(left_point),
1697                        left_offset,
1698                        "point_to_offset({:?})",
1699                        left_point,
1700                    );
1701                    assert_eq!(
1702                        snapshot.offset_to_point(left_offset),
1703                        left_point,
1704                        "offset_to_point({:?})",
1705                        left_offset,
1706                    );
1707
1708                    offset += 1;
1709                    buffer_offset += 1;
1710                    if *byte == b'\n' {
1711                        point += Point::new(1, 0);
1712                        point_utf16 += PointUtf16::new(1, 0);
1713                        buffer_point += Point::new(1, 0);
1714                        buffer_point_utf16 += PointUtf16::new(1, 0);
1715                    } else {
1716                        point += Point::new(0, 1);
1717                        point_utf16 += PointUtf16::new(0, 1);
1718                        buffer_point += Point::new(0, 1);
1719                        buffer_point_utf16 += PointUtf16::new(0, 1);
1720                    }
1721                }
1722            }
1723
1724            for (row, line) in expected_text.split('\n').enumerate() {
1725                assert_eq!(
1726                    snapshot.line_len(row as u32),
1727                    line.len() as u32,
1728                    "line_len({}).",
1729                    row
1730                );
1731            }
1732
1733            for _ in 0..10 {
1734                let end_ix = snapshot.clip_offset(rng.gen_range(0..=snapshot.len()), Bias::Right);
1735                let start_ix = snapshot.clip_offset(rng.gen_range(0..=end_ix), Bias::Left);
1736
1737                assert_eq!(
1738                    snapshot
1739                        .text_for_range(start_ix..end_ix)
1740                        .collect::<String>(),
1741                    &expected_text[start_ix..end_ix],
1742                    "incorrect text for range {:?}",
1743                    start_ix..end_ix
1744                );
1745
1746                let expected_summary = TextSummary::from(&expected_text[start_ix..end_ix]);
1747                assert_eq!(
1748                    snapshot.text_summary_for_range::<TextSummary, _>(start_ix..end_ix),
1749                    expected_summary,
1750                    "incorrect summary for range {:?}",
1751                    start_ix..end_ix
1752                );
1753            }
1754        }
1755
1756        let snapshot = list.read(cx).snapshot(cx);
1757        for (old_snapshot, subscription) in old_versions {
1758            let edits = subscription.consume().into_inner();
1759
1760            log::info!(
1761                "applying edits since old text: {:?}: {:?}",
1762                old_snapshot.text(),
1763                edits,
1764            );
1765
1766            let mut text = old_snapshot.text();
1767            for edit in edits {
1768                let new_text: String = snapshot.text_for_range(edit.new.clone()).collect();
1769                text.replace_range(edit.new.start..edit.new.start + edit.old.len(), &new_text);
1770            }
1771            assert_eq!(text.to_string(), snapshot.text());
1772        }
1773    }
1774}