1use super::TextHighlights;
   2use crate::{
   3    multi_buffer::MultiBufferRows, Anchor, AnchorRangeExt, MultiBufferChunks, MultiBufferSnapshot,
   4    ToOffset,
   5};
   6use collections::BTreeMap;
   7use gpui::fonts::HighlightStyle;
   8use language::{Chunk, Edit, Point, PointUtf16, TextSummary};
   9use parking_lot::Mutex;
  10use std::{
  11    any::TypeId,
  12    cmp::{self, Ordering},
  13    iter::{self, Peekable},
  14    ops::{Range, Sub},
  15    sync::atomic::{AtomicUsize, Ordering::SeqCst},
  16    vec,
  17};
  18use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  19
  20#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  21pub struct FoldPoint(pub super::Point);
  22
  23impl FoldPoint {
  24    pub fn new(row: u32, column: u32) -> Self {
  25        Self(super::Point::new(row, column))
  26    }
  27
  28    pub fn row(self) -> u32 {
  29        self.0.row
  30    }
  31
  32    pub fn column(self) -> u32 {
  33        self.0.column
  34    }
  35
  36    pub fn row_mut(&mut self) -> &mut u32 {
  37        &mut self.0.row
  38    }
  39
  40    pub fn column_mut(&mut self) -> &mut u32 {
  41        &mut self.0.column
  42    }
  43
  44    pub fn to_buffer_point(&self, snapshot: &FoldSnapshot) -> Point {
  45        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  46        cursor.seek(self, Bias::Right, &());
  47        let overshoot = self.0 - cursor.start().0 .0;
  48        cursor.start().1 + overshoot
  49    }
  50
  51    pub fn to_buffer_offset(&self, snapshot: &FoldSnapshot) -> usize {
  52        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  53        cursor.seek(self, Bias::Right, &());
  54        let overshoot = self.0 - cursor.start().0 .0;
  55        snapshot
  56            .buffer_snapshot
  57            .point_to_offset(cursor.start().1 + overshoot)
  58    }
  59
  60    pub fn to_offset(&self, snapshot: &FoldSnapshot) -> FoldOffset {
  61        let mut cursor = snapshot
  62            .transforms
  63            .cursor::<(FoldPoint, TransformSummary)>();
  64        cursor.seek(self, Bias::Right, &());
  65        let overshoot = self.0 - cursor.start().1.output.lines;
  66        let mut offset = cursor.start().1.output.bytes;
  67        if !overshoot.is_zero() {
  68            let transform = cursor.item().expect("display point out of range");
  69            assert!(transform.output_text.is_none());
  70            let end_buffer_offset = snapshot
  71                .buffer_snapshot
  72                .point_to_offset(cursor.start().1.input.lines + overshoot);
  73            offset += end_buffer_offset - cursor.start().1.input.bytes;
  74        }
  75        FoldOffset(offset)
  76    }
  77}
  78
  79impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
  80    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
  81        self.0 += &summary.output.lines;
  82    }
  83}
  84
  85pub struct FoldMapWriter<'a>(&'a mut FoldMap);
  86
  87impl<'a> FoldMapWriter<'a> {
  88    pub fn fold<T: ToOffset>(
  89        &mut self,
  90        ranges: impl IntoIterator<Item = Range<T>>,
  91    ) -> (FoldSnapshot, Vec<FoldEdit>) {
  92        let mut edits = Vec::new();
  93        let mut folds = Vec::new();
  94        let buffer = self.0.buffer.lock().clone();
  95        for range in ranges.into_iter() {
  96            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
  97
  98            // Ignore any empty ranges.
  99            if range.start == range.end {
 100                continue;
 101            }
 102
 103            // For now, ignore any ranges that span an excerpt boundary.
 104            let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 105            if fold.0.start.excerpt_id() != fold.0.end.excerpt_id() {
 106                continue;
 107            }
 108
 109            folds.push(fold);
 110            edits.push(text::Edit {
 111                old: range.clone(),
 112                new: range,
 113            });
 114        }
 115
 116        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 117
 118        self.0.folds = {
 119            let mut new_tree = SumTree::new();
 120            let mut cursor = self.0.folds.cursor::<Fold>();
 121            for fold in folds {
 122                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 123                new_tree.push(fold, &buffer);
 124            }
 125            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 126            new_tree
 127        };
 128
 129        consolidate_buffer_edits(&mut edits);
 130        let edits = self.0.sync(buffer.clone(), edits);
 131        let snapshot = FoldSnapshot {
 132            transforms: self.0.transforms.lock().clone(),
 133            folds: self.0.folds.clone(),
 134            buffer_snapshot: buffer,
 135            version: self.0.version.load(SeqCst),
 136        };
 137        (snapshot, edits)
 138    }
 139
 140    pub fn unfold<T: ToOffset>(
 141        &mut self,
 142        ranges: impl IntoIterator<Item = Range<T>>,
 143    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 144        let mut edits = Vec::new();
 145        let mut fold_ixs_to_delete = Vec::new();
 146        let buffer = self.0.buffer.lock().clone();
 147        for range in ranges.into_iter() {
 148            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 149            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 150            while let Some(fold) = folds_cursor.item() {
 151                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 152                if offset_range.end > offset_range.start {
 153                    edits.push(text::Edit {
 154                        old: offset_range.clone(),
 155                        new: offset_range,
 156                    });
 157                }
 158                fold_ixs_to_delete.push(*folds_cursor.start());
 159                folds_cursor.next(&buffer);
 160            }
 161        }
 162
 163        fold_ixs_to_delete.sort_unstable();
 164        fold_ixs_to_delete.dedup();
 165
 166        self.0.folds = {
 167            let mut cursor = self.0.folds.cursor::<usize>();
 168            let mut folds = SumTree::new();
 169            for fold_ix in fold_ixs_to_delete {
 170                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 171                cursor.next(&buffer);
 172            }
 173            folds.push_tree(cursor.suffix(&buffer), &buffer);
 174            folds
 175        };
 176
 177        consolidate_buffer_edits(&mut edits);
 178        let edits = self.0.sync(buffer.clone(), edits);
 179        let snapshot = FoldSnapshot {
 180            transforms: self.0.transforms.lock().clone(),
 181            folds: self.0.folds.clone(),
 182            buffer_snapshot: buffer,
 183            version: self.0.version.load(SeqCst),
 184        };
 185        (snapshot, edits)
 186    }
 187}
 188
 189pub struct FoldMap {
 190    buffer: Mutex<MultiBufferSnapshot>,
 191    transforms: Mutex<SumTree<Transform>>,
 192    folds: SumTree<Fold>,
 193    version: AtomicUsize,
 194}
 195
 196impl FoldMap {
 197    pub fn new(buffer: MultiBufferSnapshot) -> (Self, FoldSnapshot) {
 198        let this = Self {
 199            buffer: Mutex::new(buffer.clone()),
 200            folds: Default::default(),
 201            transforms: Mutex::new(SumTree::from_item(
 202                Transform {
 203                    summary: TransformSummary {
 204                        input: buffer.text_summary(),
 205                        output: buffer.text_summary(),
 206                    },
 207                    output_text: None,
 208                },
 209                &(),
 210            )),
 211            version: Default::default(),
 212        };
 213
 214        let snapshot = FoldSnapshot {
 215            transforms: this.transforms.lock().clone(),
 216            folds: this.folds.clone(),
 217            buffer_snapshot: this.buffer.lock().clone(),
 218            version: this.version.load(SeqCst),
 219        };
 220        (this, snapshot)
 221    }
 222
 223    pub fn read(
 224        &self,
 225        buffer: MultiBufferSnapshot,
 226        edits: Vec<Edit<usize>>,
 227    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 228        let edits = self.sync(buffer, edits);
 229        self.check_invariants();
 230        let snapshot = FoldSnapshot {
 231            transforms: self.transforms.lock().clone(),
 232            folds: self.folds.clone(),
 233            buffer_snapshot: self.buffer.lock().clone(),
 234            version: self.version.load(SeqCst),
 235        };
 236        (snapshot, edits)
 237    }
 238
 239    pub fn write(
 240        &mut self,
 241        buffer: MultiBufferSnapshot,
 242        edits: Vec<Edit<usize>>,
 243    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 244        let (snapshot, edits) = self.read(buffer, edits);
 245        (FoldMapWriter(self), snapshot, edits)
 246    }
 247
 248    fn check_invariants(&self) {
 249        if cfg!(test) {
 250            assert_eq!(
 251                self.transforms.lock().summary().input.bytes,
 252                self.buffer.lock().len(),
 253                "transform tree does not match buffer's length"
 254            );
 255        }
 256    }
 257
 258    fn sync(
 259        &self,
 260        new_buffer: MultiBufferSnapshot,
 261        buffer_edits: Vec<text::Edit<usize>>,
 262    ) -> Vec<FoldEdit> {
 263        if buffer_edits.is_empty() {
 264            let mut buffer = self.buffer.lock();
 265            if buffer.parse_count() != new_buffer.parse_count()
 266                || buffer.diagnostics_update_count() != new_buffer.diagnostics_update_count()
 267                || buffer.trailing_excerpt_update_count()
 268                    != new_buffer.trailing_excerpt_update_count()
 269            {
 270                self.version.fetch_add(1, SeqCst);
 271            }
 272            *buffer = new_buffer;
 273            Vec::new()
 274        } else {
 275            let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 276
 277            let mut new_transforms = SumTree::new();
 278            let mut transforms = self.transforms.lock();
 279            let mut cursor = transforms.cursor::<usize>();
 280            cursor.seek(&0, Bias::Right, &());
 281
 282            while let Some(mut edit) = buffer_edits_iter.next() {
 283                new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 284                edit.new.start -= edit.old.start - cursor.start();
 285                edit.old.start = *cursor.start();
 286
 287                cursor.seek(&edit.old.end, Bias::Right, &());
 288                cursor.next(&());
 289
 290                let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 291                loop {
 292                    edit.old.end = *cursor.start();
 293
 294                    if let Some(next_edit) = buffer_edits_iter.peek() {
 295                        if next_edit.old.start > edit.old.end {
 296                            break;
 297                        }
 298
 299                        let next_edit = buffer_edits_iter.next().unwrap();
 300                        delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 301
 302                        if next_edit.old.end >= edit.old.end {
 303                            edit.old.end = next_edit.old.end;
 304                            cursor.seek(&edit.old.end, Bias::Right, &());
 305                            cursor.next(&());
 306                        }
 307                    } else {
 308                        break;
 309                    }
 310                }
 311
 312                edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 313
 314                let anchor = new_buffer.anchor_before(edit.new.start);
 315                let mut folds_cursor = self.folds.cursor::<Fold>();
 316                folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &new_buffer);
 317
 318                let mut folds = iter::from_fn({
 319                    let buffer = &new_buffer;
 320                    move || {
 321                        let item = folds_cursor
 322                            .item()
 323                            .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 324                        folds_cursor.next(buffer);
 325                        item
 326                    }
 327                })
 328                .peekable();
 329
 330                while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 331                    let mut fold = folds.next().unwrap();
 332                    let sum = new_transforms.summary();
 333
 334                    assert!(fold.start >= sum.input.bytes);
 335
 336                    while folds
 337                        .peek()
 338                        .map_or(false, |next_fold| next_fold.start <= fold.end)
 339                    {
 340                        let next_fold = folds.next().unwrap();
 341                        if next_fold.end > fold.end {
 342                            fold.end = next_fold.end;
 343                        }
 344                    }
 345
 346                    if fold.start > sum.input.bytes {
 347                        let text_summary = new_buffer
 348                            .text_summary_for_range::<TextSummary, _>(sum.input.bytes..fold.start);
 349                        new_transforms.push(
 350                            Transform {
 351                                summary: TransformSummary {
 352                                    output: text_summary.clone(),
 353                                    input: text_summary,
 354                                },
 355                                output_text: None,
 356                            },
 357                            &(),
 358                        );
 359                    }
 360
 361                    if fold.end > fold.start {
 362                        let output_text = "…";
 363                        let chars = output_text.chars().count() as u32;
 364                        let lines = Point::new(0, output_text.len() as u32);
 365                        let lines_utf16 =
 366                            PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 367                        new_transforms.push(
 368                            Transform {
 369                                summary: TransformSummary {
 370                                    output: TextSummary {
 371                                        bytes: output_text.len(),
 372                                        lines,
 373                                        lines_utf16,
 374                                        first_line_chars: chars,
 375                                        last_line_chars: chars,
 376                                        longest_row: 0,
 377                                        longest_row_chars: chars,
 378                                    },
 379                                    input: new_buffer.text_summary_for_range(fold.start..fold.end),
 380                                },
 381                                output_text: Some(output_text),
 382                            },
 383                            &(),
 384                        );
 385                    }
 386                }
 387
 388                let sum = new_transforms.summary();
 389                if sum.input.bytes < edit.new.end {
 390                    let text_summary = new_buffer
 391                        .text_summary_for_range::<TextSummary, _>(sum.input.bytes..edit.new.end);
 392                    new_transforms.push(
 393                        Transform {
 394                            summary: TransformSummary {
 395                                output: text_summary.clone(),
 396                                input: text_summary,
 397                            },
 398                            output_text: None,
 399                        },
 400                        &(),
 401                    );
 402                }
 403            }
 404
 405            new_transforms.push_tree(cursor.suffix(&()), &());
 406            if new_transforms.is_empty() {
 407                let text_summary = new_buffer.text_summary();
 408                new_transforms.push(
 409                    Transform {
 410                        summary: TransformSummary {
 411                            output: text_summary.clone(),
 412                            input: text_summary,
 413                        },
 414                        output_text: None,
 415                    },
 416                    &(),
 417                );
 418            }
 419
 420            drop(cursor);
 421
 422            let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 423            {
 424                let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 425                let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 426
 427                for mut edit in buffer_edits {
 428                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 429                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 430                        edit.old.start = old_transforms.start().0;
 431                    }
 432                    let old_start =
 433                        old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 434
 435                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 436                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 437                        old_transforms.next(&());
 438                        edit.old.end = old_transforms.start().0;
 439                    }
 440                    let old_end =
 441                        old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 442
 443                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 444                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 445                        edit.new.start = new_transforms.start().0;
 446                    }
 447                    let new_start =
 448                        new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 449
 450                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 451                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 452                        new_transforms.next(&());
 453                        edit.new.end = new_transforms.start().0;
 454                    }
 455                    let new_end =
 456                        new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 457
 458                    fold_edits.push(FoldEdit {
 459                        old: FoldOffset(old_start)..FoldOffset(old_end),
 460                        new: FoldOffset(new_start)..FoldOffset(new_end),
 461                    });
 462                }
 463
 464                consolidate_fold_edits(&mut fold_edits);
 465            }
 466
 467            *transforms = new_transforms;
 468            *self.buffer.lock() = new_buffer;
 469            self.version.fetch_add(1, SeqCst);
 470            fold_edits
 471        }
 472    }
 473}
 474
 475#[derive(Clone)]
 476pub struct FoldSnapshot {
 477    transforms: SumTree<Transform>,
 478    folds: SumTree<Fold>,
 479    buffer_snapshot: MultiBufferSnapshot,
 480    pub version: usize,
 481}
 482
 483impl FoldSnapshot {
 484    pub fn buffer_snapshot(&self) -> &MultiBufferSnapshot {
 485        &self.buffer_snapshot
 486    }
 487
 488    #[cfg(test)]
 489    pub fn text(&self) -> String {
 490        self.chunks(FoldOffset(0)..self.len(), false, None)
 491            .map(|c| c.text)
 492            .collect()
 493    }
 494
 495    #[cfg(test)]
 496    pub fn fold_count(&self) -> usize {
 497        self.folds.items(&self.buffer_snapshot).len()
 498    }
 499
 500    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 501        let mut summary = TextSummary::default();
 502
 503        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 504        cursor.seek(&range.start, Bias::Right, &());
 505        if let Some(transform) = cursor.item() {
 506            let start_in_transform = range.start.0 - cursor.start().0 .0;
 507            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 508            if let Some(output_text) = transform.output_text {
 509                summary = TextSummary::from(
 510                    &output_text
 511                        [start_in_transform.column as usize..end_in_transform.column as usize],
 512                );
 513            } else {
 514                let buffer_start = cursor.start().1 + start_in_transform;
 515                let buffer_end = cursor.start().1 + end_in_transform;
 516                summary = self
 517                    .buffer_snapshot
 518                    .text_summary_for_range(buffer_start..buffer_end);
 519            }
 520        }
 521
 522        if range.end > cursor.end(&()).0 {
 523            cursor.next(&());
 524            summary += &cursor
 525                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 526                .output;
 527            if let Some(transform) = cursor.item() {
 528                let end_in_transform = range.end.0 - cursor.start().0 .0;
 529                if let Some(output_text) = transform.output_text {
 530                    summary += TextSummary::from(&output_text[..end_in_transform.column as usize]);
 531                } else {
 532                    let buffer_start = cursor.start().1;
 533                    let buffer_end = cursor.start().1 + end_in_transform;
 534                    summary += self
 535                        .buffer_snapshot
 536                        .text_summary_for_range::<TextSummary, _>(buffer_start..buffer_end);
 537                }
 538            }
 539        }
 540
 541        summary
 542    }
 543
 544    pub fn to_fold_point(&self, point: Point, bias: Bias) -> FoldPoint {
 545        let mut cursor = self.transforms.cursor::<(Point, FoldPoint)>();
 546        cursor.seek(&point, Bias::Right, &());
 547        if cursor.item().map_or(false, |t| t.is_fold()) {
 548            if bias == Bias::Left || point == cursor.start().0 {
 549                cursor.start().1
 550            } else {
 551                cursor.end(&()).1
 552            }
 553        } else {
 554            let overshoot = point - cursor.start().0;
 555            FoldPoint(cmp::min(
 556                cursor.start().1 .0 + overshoot,
 557                cursor.end(&()).1 .0,
 558            ))
 559        }
 560    }
 561
 562    pub fn len(&self) -> FoldOffset {
 563        FoldOffset(self.transforms.summary().output.bytes)
 564    }
 565
 566    pub fn line_len(&self, row: u32) -> u32 {
 567        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 568        let line_end = if row >= self.max_point().row() {
 569            self.len().0
 570        } else {
 571            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 572        };
 573        (line_end - line_start) as u32
 574    }
 575
 576    pub fn buffer_rows(&self, start_row: u32) -> FoldBufferRows {
 577        if start_row > self.transforms.summary().output.lines.row {
 578            panic!("invalid display row {}", start_row);
 579        }
 580
 581        let fold_point = FoldPoint::new(start_row, 0);
 582        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 583        cursor.seek(&fold_point, Bias::Left, &());
 584
 585        let overshoot = fold_point.0 - cursor.start().0 .0;
 586        let buffer_point = cursor.start().1 + overshoot;
 587        let input_buffer_rows = self.buffer_snapshot.buffer_rows(buffer_point.row);
 588
 589        FoldBufferRows {
 590            fold_point,
 591            input_buffer_rows,
 592            cursor,
 593        }
 594    }
 595
 596    pub fn max_point(&self) -> FoldPoint {
 597        FoldPoint(self.transforms.summary().output.lines)
 598    }
 599
 600    #[cfg(test)]
 601    pub fn longest_row(&self) -> u32 {
 602        self.transforms.summary().output.longest_row
 603    }
 604
 605    pub fn folds_in_range<'a, T>(
 606        &'a self,
 607        range: Range<T>,
 608    ) -> impl Iterator<Item = &'a Range<Anchor>>
 609    where
 610        T: ToOffset,
 611    {
 612        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 613        iter::from_fn(move || {
 614            let item = folds.item().map(|f| &f.0);
 615            folds.next(&self.buffer_snapshot);
 616            item
 617        })
 618    }
 619
 620    pub fn intersects_fold<T>(&self, offset: T) -> bool
 621    where
 622        T: ToOffset,
 623    {
 624        let offset = offset.to_offset(&self.buffer_snapshot);
 625        let mut cursor = self.transforms.cursor::<usize>();
 626        cursor.seek(&offset, Bias::Right, &());
 627        cursor.item().map_or(false, |t| t.output_text.is_some())
 628    }
 629
 630    pub fn is_line_folded(&self, output_row: u32) -> bool {
 631        let mut cursor = self.transforms.cursor::<FoldPoint>();
 632        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 633        while let Some(transform) = cursor.item() {
 634            if transform.output_text.is_some() {
 635                return true;
 636            }
 637            if cursor.end(&()).row() == output_row {
 638                cursor.next(&())
 639            } else {
 640                break;
 641            }
 642        }
 643        false
 644    }
 645
 646    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 647        let start = start.to_offset(self);
 648        self.chunks(start..self.len(), false, None)
 649            .flat_map(|chunk| chunk.text.chars())
 650    }
 651
 652    pub fn chunks<'a>(
 653        &'a self,
 654        range: Range<FoldOffset>,
 655        language_aware: bool,
 656        text_highlights: Option<&'a TextHighlights>,
 657    ) -> FoldChunks<'a> {
 658        let mut highlight_endpoints = Vec::new();
 659        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 660
 661        let buffer_end = {
 662            transform_cursor.seek(&range.end, Bias::Right, &());
 663            let overshoot = range.end.0 - transform_cursor.start().0 .0;
 664            transform_cursor.start().1 + overshoot
 665        };
 666
 667        let buffer_start = {
 668            transform_cursor.seek(&range.start, Bias::Right, &());
 669            let overshoot = range.start.0 - transform_cursor.start().0 .0;
 670            transform_cursor.start().1 + overshoot
 671        };
 672
 673        if let Some(text_highlights) = text_highlights {
 674            if !text_highlights.is_empty() {
 675                while transform_cursor.start().0 < range.end {
 676                    if !transform_cursor.item().unwrap().is_fold() {
 677                        let transform_start = self
 678                            .buffer_snapshot
 679                            .anchor_after(cmp::max(buffer_start, transform_cursor.start().1));
 680
 681                        let transform_end = {
 682                            let overshoot = range.end.0 - transform_cursor.start().0 .0;
 683                            self.buffer_snapshot.anchor_before(cmp::min(
 684                                transform_cursor.end(&()).1,
 685                                transform_cursor.start().1 + overshoot,
 686                            ))
 687                        };
 688
 689                        for (tag, highlights) in text_highlights.iter() {
 690                            let style = highlights.0;
 691                            let ranges = &highlights.1;
 692
 693                            let start_ix = match ranges.binary_search_by(|probe| {
 694                                let cmp = probe
 695                                    .end
 696                                    .cmp(&transform_start, &self.buffer_snapshot())
 697                                    .unwrap();
 698                                if cmp.is_gt() {
 699                                    Ordering::Greater
 700                                } else {
 701                                    Ordering::Less
 702                                }
 703                            }) {
 704                                Ok(i) | Err(i) => i,
 705                            };
 706                            for range in &ranges[start_ix..] {
 707                                if range
 708                                    .start
 709                                    .cmp(&transform_end, &self.buffer_snapshot)
 710                                    .unwrap()
 711                                    .is_ge()
 712                                {
 713                                    break;
 714                                }
 715
 716                                highlight_endpoints.push(HighlightEndpoint {
 717                                    offset: range.start.to_offset(&self.buffer_snapshot),
 718                                    is_start: true,
 719                                    tag: *tag,
 720                                    style,
 721                                });
 722                                highlight_endpoints.push(HighlightEndpoint {
 723                                    offset: range.end.to_offset(&self.buffer_snapshot),
 724                                    is_start: false,
 725                                    tag: *tag,
 726                                    style,
 727                                });
 728                            }
 729                        }
 730                    }
 731
 732                    transform_cursor.next(&());
 733                }
 734                highlight_endpoints.sort();
 735                transform_cursor.seek(&range.start, Bias::Right, &());
 736            }
 737        }
 738
 739        FoldChunks {
 740            transform_cursor,
 741            buffer_chunks: self
 742                .buffer_snapshot
 743                .chunks(buffer_start..buffer_end, language_aware),
 744            buffer_chunk: None,
 745            buffer_offset: buffer_start,
 746            output_offset: range.start.0,
 747            max_output_offset: range.end.0,
 748            highlight_endpoints: highlight_endpoints.into_iter().peekable(),
 749            active_highlights: Default::default(),
 750        }
 751    }
 752
 753    #[cfg(test)]
 754    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 755        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 756        cursor.seek(&offset, Bias::Right, &());
 757        if let Some(transform) = cursor.item() {
 758            let transform_start = cursor.start().0 .0;
 759            if transform.output_text.is_some() {
 760                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 761                    FoldOffset(transform_start)
 762                } else {
 763                    FoldOffset(cursor.end(&()).0 .0)
 764                }
 765            } else {
 766                let overshoot = offset.0 - transform_start;
 767                let buffer_offset = cursor.start().1 + overshoot;
 768                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 769                FoldOffset(
 770                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 771                        as usize,
 772                )
 773            }
 774        } else {
 775            FoldOffset(self.transforms.summary().output.bytes)
 776        }
 777    }
 778
 779    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 780        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 781        cursor.seek(&point, Bias::Right, &());
 782        if let Some(transform) = cursor.item() {
 783            let transform_start = cursor.start().0 .0;
 784            if transform.output_text.is_some() {
 785                if point.0 == transform_start || matches!(bias, Bias::Left) {
 786                    FoldPoint(transform_start)
 787                } else {
 788                    FoldPoint(cursor.end(&()).0 .0)
 789                }
 790            } else {
 791                let overshoot = point.0 - transform_start;
 792                let buffer_position = cursor.start().1 + overshoot;
 793                let clipped_buffer_position =
 794                    self.buffer_snapshot.clip_point(buffer_position, bias);
 795                FoldPoint(cursor.start().0 .0 + (clipped_buffer_position - cursor.start().1))
 796            }
 797        } else {
 798            FoldPoint(self.transforms.summary().output.lines)
 799        }
 800    }
 801}
 802
 803fn intersecting_folds<'a, T>(
 804    buffer: &'a MultiBufferSnapshot,
 805    folds: &'a SumTree<Fold>,
 806    range: Range<T>,
 807    inclusive: bool,
 808) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 809where
 810    T: ToOffset,
 811{
 812    let start = buffer.anchor_before(range.start.to_offset(buffer));
 813    let end = buffer.anchor_after(range.end.to_offset(buffer));
 814    folds.filter::<_, usize>(
 815        move |summary| {
 816            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 817            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 818
 819            if inclusive {
 820                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 821            } else {
 822                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 823            }
 824        },
 825        buffer,
 826    )
 827}
 828
 829fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 830    edits.sort_unstable_by(|a, b| {
 831        a.old
 832            .start
 833            .cmp(&b.old.start)
 834            .then_with(|| b.old.end.cmp(&a.old.end))
 835    });
 836
 837    let mut i = 1;
 838    while i < edits.len() {
 839        let edit = edits[i].clone();
 840        let prev_edit = &mut edits[i - 1];
 841        if prev_edit.old.end >= edit.old.start {
 842            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 843            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 844            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 845            edits.remove(i);
 846            continue;
 847        }
 848        i += 1;
 849    }
 850}
 851
 852fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 853    edits.sort_unstable_by(|a, b| {
 854        a.old
 855            .start
 856            .cmp(&b.old.start)
 857            .then_with(|| b.old.end.cmp(&a.old.end))
 858    });
 859
 860    let mut i = 1;
 861    while i < edits.len() {
 862        let edit = edits[i].clone();
 863        let prev_edit = &mut edits[i - 1];
 864        if prev_edit.old.end >= edit.old.start {
 865            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 866            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 867            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 868            edits.remove(i);
 869            continue;
 870        }
 871        i += 1;
 872    }
 873}
 874
 875#[derive(Clone, Debug, Default, Eq, PartialEq)]
 876struct Transform {
 877    summary: TransformSummary,
 878    output_text: Option<&'static str>,
 879}
 880
 881impl Transform {
 882    fn is_fold(&self) -> bool {
 883        self.output_text.is_some()
 884    }
 885}
 886
 887#[derive(Clone, Debug, Default, Eq, PartialEq)]
 888struct TransformSummary {
 889    output: TextSummary,
 890    input: TextSummary,
 891}
 892
 893impl sum_tree::Item for Transform {
 894    type Summary = TransformSummary;
 895
 896    fn summary(&self) -> Self::Summary {
 897        self.summary.clone()
 898    }
 899}
 900
 901impl sum_tree::Summary for TransformSummary {
 902    type Context = ();
 903
 904    fn add_summary(&mut self, other: &Self, _: &()) {
 905        self.input += &other.input;
 906        self.output += &other.output;
 907    }
 908}
 909
 910#[derive(Clone, Debug)]
 911struct Fold(Range<Anchor>);
 912
 913impl Default for Fold {
 914    fn default() -> Self {
 915        Self(Anchor::min()..Anchor::max())
 916    }
 917}
 918
 919impl sum_tree::Item for Fold {
 920    type Summary = FoldSummary;
 921
 922    fn summary(&self) -> Self::Summary {
 923        FoldSummary {
 924            start: self.0.start.clone(),
 925            end: self.0.end.clone(),
 926            min_start: self.0.start.clone(),
 927            max_end: self.0.end.clone(),
 928            count: 1,
 929        }
 930    }
 931}
 932
 933#[derive(Clone, Debug)]
 934struct FoldSummary {
 935    start: Anchor,
 936    end: Anchor,
 937    min_start: Anchor,
 938    max_end: Anchor,
 939    count: usize,
 940}
 941
 942impl Default for FoldSummary {
 943    fn default() -> Self {
 944        Self {
 945            start: Anchor::min(),
 946            end: Anchor::max(),
 947            min_start: Anchor::max(),
 948            max_end: Anchor::min(),
 949            count: 0,
 950        }
 951    }
 952}
 953
 954impl sum_tree::Summary for FoldSummary {
 955    type Context = MultiBufferSnapshot;
 956
 957    fn add_summary(&mut self, other: &Self, buffer: &MultiBufferSnapshot) {
 958        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 959            self.min_start = other.min_start.clone();
 960        }
 961        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 962            self.max_end = other.max_end.clone();
 963        }
 964
 965        #[cfg(debug_assertions)]
 966        {
 967            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 968            assert!(start_comparison <= Ordering::Equal);
 969            if start_comparison == Ordering::Equal {
 970                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 971            }
 972        }
 973
 974        self.start = other.start.clone();
 975        self.end = other.end.clone();
 976        self.count += other.count;
 977    }
 978}
 979
 980impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 981    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 982        self.0.start = summary.start.clone();
 983        self.0.end = summary.end.clone();
 984    }
 985}
 986
 987impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 988    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
 989        self.0.cmp(&other.0, buffer).unwrap()
 990    }
 991}
 992
 993impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 994    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 995        *self += summary.count;
 996    }
 997}
 998
 999pub struct FoldBufferRows<'a> {
1000    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
1001    input_buffer_rows: MultiBufferRows<'a>,
1002    fold_point: FoldPoint,
1003}
1004
1005impl<'a> Iterator for FoldBufferRows<'a> {
1006    type Item = Option<u32>;
1007
1008    fn next(&mut self) -> Option<Self::Item> {
1009        let mut traversed_fold = false;
1010        while self.fold_point > self.cursor.end(&()).0 {
1011            self.cursor.next(&());
1012            traversed_fold = true;
1013            if self.cursor.item().is_none() {
1014                break;
1015            }
1016        }
1017
1018        if self.cursor.item().is_some() {
1019            if traversed_fold {
1020                self.input_buffer_rows.seek(self.cursor.start().1.row);
1021                self.input_buffer_rows.next();
1022            }
1023            *self.fold_point.row_mut() += 1;
1024            self.input_buffer_rows.next()
1025        } else {
1026            None
1027        }
1028    }
1029}
1030
1031pub struct FoldChunks<'a> {
1032    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
1033    buffer_chunks: MultiBufferChunks<'a>,
1034    buffer_chunk: Option<(usize, Chunk<'a>)>,
1035    buffer_offset: usize,
1036    output_offset: usize,
1037    max_output_offset: usize,
1038    highlight_endpoints: Peekable<vec::IntoIter<HighlightEndpoint>>,
1039    active_highlights: BTreeMap<Option<TypeId>, HighlightStyle>,
1040}
1041
1042impl<'a> Iterator for FoldChunks<'a> {
1043    type Item = Chunk<'a>;
1044
1045    fn next(&mut self) -> Option<Self::Item> {
1046        if self.output_offset >= self.max_output_offset {
1047            return None;
1048        }
1049
1050        let transform = if let Some(item) = self.transform_cursor.item() {
1051            item
1052        } else {
1053            return None;
1054        };
1055
1056        // If we're in a fold, then return the fold's display text and
1057        // advance the transform and buffer cursors to the end of the fold.
1058        if let Some(output_text) = transform.output_text {
1059            self.buffer_chunk.take();
1060            self.buffer_offset += transform.summary.input.bytes;
1061            self.buffer_chunks.seek(self.buffer_offset);
1062
1063            while self.buffer_offset >= self.transform_cursor.end(&()).1
1064                && self.transform_cursor.item().is_some()
1065            {
1066                self.transform_cursor.next(&());
1067            }
1068
1069            self.output_offset += output_text.len();
1070            return Some(Chunk {
1071                text: output_text,
1072                syntax_highlight_id: None,
1073                highlight_style: None,
1074                diagnostic: None,
1075            });
1076        }
1077
1078        let mut next_highlight_endpoint = usize::MAX;
1079        while let Some(endpoint) = self.highlight_endpoints.peek().copied() {
1080            if endpoint.offset <= self.buffer_offset {
1081                if endpoint.is_start {
1082                    self.active_highlights.insert(endpoint.tag, endpoint.style);
1083                } else {
1084                    self.active_highlights.remove(&endpoint.tag);
1085                }
1086                self.highlight_endpoints.next();
1087            } else {
1088                next_highlight_endpoint = endpoint.offset;
1089                break;
1090            }
1091        }
1092
1093        // Retrieve a chunk from the current location in the buffer.
1094        if self.buffer_chunk.is_none() {
1095            let chunk_offset = self.buffer_chunks.offset();
1096            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
1097        }
1098
1099        // Otherwise, take a chunk from the buffer's text.
1100        if let Some((buffer_chunk_start, mut chunk)) = self.buffer_chunk {
1101            let buffer_chunk_end = buffer_chunk_start + chunk.text.len();
1102            let transform_end = self.transform_cursor.end(&()).1;
1103            let chunk_end = buffer_chunk_end
1104                .min(transform_end)
1105                .min(next_highlight_endpoint);
1106
1107            chunk.text = &chunk.text
1108                [self.buffer_offset - buffer_chunk_start..chunk_end - buffer_chunk_start];
1109
1110            if !self.active_highlights.is_empty() {
1111                let mut highlight_style = HighlightStyle::default();
1112                for active_highlight in self.active_highlights.values() {
1113                    highlight_style.highlight(*active_highlight);
1114                }
1115                chunk.highlight_style = Some(highlight_style);
1116            }
1117
1118            if chunk_end == transform_end {
1119                self.transform_cursor.next(&());
1120            } else if chunk_end == buffer_chunk_end {
1121                self.buffer_chunk.take();
1122            }
1123
1124            self.buffer_offset = chunk_end;
1125            self.output_offset += chunk.text.len();
1126            return Some(chunk);
1127        }
1128
1129        None
1130    }
1131}
1132
1133#[derive(Copy, Clone, Eq, PartialEq)]
1134struct HighlightEndpoint {
1135    offset: usize,
1136    is_start: bool,
1137    tag: Option<TypeId>,
1138    style: HighlightStyle,
1139}
1140
1141impl PartialOrd for HighlightEndpoint {
1142    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
1143        Some(self.cmp(other))
1144    }
1145}
1146
1147impl Ord for HighlightEndpoint {
1148    fn cmp(&self, other: &Self) -> Ordering {
1149        self.offset
1150            .cmp(&other.offset)
1151            .then_with(|| self.is_start.cmp(&other.is_start))
1152    }
1153}
1154
1155#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1156pub struct FoldOffset(pub usize);
1157
1158impl FoldOffset {
1159    pub fn to_point(&self, snapshot: &FoldSnapshot) -> FoldPoint {
1160        let mut cursor = snapshot
1161            .transforms
1162            .cursor::<(FoldOffset, TransformSummary)>();
1163        cursor.seek(self, Bias::Right, &());
1164        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1165            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1166        } else {
1167            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1168            let buffer_point = snapshot.buffer_snapshot.offset_to_point(buffer_offset);
1169            buffer_point - cursor.start().1.input.lines
1170        };
1171        FoldPoint(cursor.start().1.output.lines + overshoot)
1172    }
1173}
1174
1175impl Sub for FoldOffset {
1176    type Output = Self;
1177
1178    fn sub(self, rhs: Self) -> Self::Output {
1179        Self(self.0 - rhs.0)
1180    }
1181}
1182
1183impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1184    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1185        self.0 += &summary.output.bytes;
1186    }
1187}
1188
1189impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1190    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1191        *self += &summary.input.lines;
1192    }
1193}
1194
1195impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1196    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1197        *self += &summary.input.bytes;
1198    }
1199}
1200
1201pub type FoldEdit = Edit<FoldOffset>;
1202
1203#[cfg(test)]
1204mod tests {
1205    use super::*;
1206    use crate::{MultiBuffer, ToPoint};
1207    use rand::prelude::*;
1208    use std::{cmp::Reverse, env, mem, sync::Arc};
1209    use sum_tree::TreeMap;
1210    use text::RandomCharIter;
1211    use util::test::sample_text;
1212    use Bias::{Left, Right};
1213
1214    #[gpui::test]
1215    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1216        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1217        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1218        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1219        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1220
1221        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1222        let (snapshot2, edits) = writer.fold(vec![
1223            Point::new(0, 2)..Point::new(2, 2),
1224            Point::new(2, 4)..Point::new(4, 1),
1225        ]);
1226        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1227        assert_eq!(
1228            edits,
1229            &[
1230                FoldEdit {
1231                    old: FoldOffset(2)..FoldOffset(16),
1232                    new: FoldOffset(2)..FoldOffset(5),
1233                },
1234                FoldEdit {
1235                    old: FoldOffset(18)..FoldOffset(29),
1236                    new: FoldOffset(7)..FoldOffset(10)
1237                },
1238            ]
1239        );
1240
1241        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1242            buffer.edit(
1243                vec![
1244                    Point::new(0, 0)..Point::new(0, 1),
1245                    Point::new(2, 3)..Point::new(2, 3),
1246                ],
1247                "123",
1248                cx,
1249            );
1250            buffer.snapshot(cx)
1251        });
1252        let (snapshot3, edits) =
1253            map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1254        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1255        assert_eq!(
1256            edits,
1257            &[
1258                FoldEdit {
1259                    old: FoldOffset(0)..FoldOffset(1),
1260                    new: FoldOffset(0)..FoldOffset(3),
1261                },
1262                FoldEdit {
1263                    old: FoldOffset(6)..FoldOffset(6),
1264                    new: FoldOffset(8)..FoldOffset(11),
1265                },
1266            ]
1267        );
1268
1269        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1270            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1271            buffer.snapshot(cx)
1272        });
1273        let (snapshot4, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1274        assert_eq!(snapshot4.text(), "123a…c123456eee");
1275
1276        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1277        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1278        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1279        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1280    }
1281
1282    #[gpui::test]
1283    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1284        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1285        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1286        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1287
1288        {
1289            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1290
1291            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1292            writer.fold(vec![5..8]);
1293            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1294            assert_eq!(snapshot.text(), "abcde…ijkl");
1295
1296            // Create an fold adjacent to the start of the first fold.
1297            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1298            writer.fold(vec![0..1, 2..5]);
1299            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1300            assert_eq!(snapshot.text(), "…b…ijkl");
1301
1302            // Create an fold adjacent to the end of the first fold.
1303            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1304            writer.fold(vec![11..11, 8..10]);
1305            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1306            assert_eq!(snapshot.text(), "…b…kl");
1307        }
1308
1309        {
1310            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1311
1312            // Create two adjacent folds.
1313            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1314            writer.fold(vec![0..2, 2..5]);
1315            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1316            assert_eq!(snapshot.text(), "…fghijkl");
1317
1318            // Edit within one of the folds.
1319            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1320                buffer.edit(vec![0..1], "12345", cx);
1321                buffer.snapshot(cx)
1322            });
1323            let (snapshot, _) =
1324                map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1325            assert_eq!(snapshot.text(), "12345…fghijkl");
1326        }
1327    }
1328
1329    #[gpui::test]
1330    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1331        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1332        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1333        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1334        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1335        writer.fold(vec![
1336            Point::new(0, 2)..Point::new(2, 2),
1337            Point::new(0, 4)..Point::new(1, 0),
1338            Point::new(1, 2)..Point::new(3, 2),
1339            Point::new(3, 1)..Point::new(4, 1),
1340        ]);
1341        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1342        assert_eq!(snapshot.text(), "aa…eeeee");
1343    }
1344
1345    #[gpui::test]
1346    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1347        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1348        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1349        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1350        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1351
1352        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1353        writer.fold(vec![
1354            Point::new(0, 2)..Point::new(2, 2),
1355            Point::new(3, 1)..Point::new(4, 1),
1356        ]);
1357        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1358        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1359
1360        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1361            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1362            buffer.snapshot(cx)
1363        });
1364        let (snapshot, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1365        assert_eq!(snapshot.text(), "aa…eeeee");
1366    }
1367
1368    #[gpui::test]
1369    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1370        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1371        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1372        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1373
1374        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1375        writer.fold(vec![
1376            Point::new(0, 2)..Point::new(2, 2),
1377            Point::new(0, 4)..Point::new(1, 0),
1378            Point::new(1, 2)..Point::new(3, 2),
1379            Point::new(3, 1)..Point::new(4, 1),
1380        ]);
1381        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1382        let fold_ranges = snapshot
1383            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1384            .map(|fold| fold.start.to_point(&buffer_snapshot)..fold.end.to_point(&buffer_snapshot))
1385            .collect::<Vec<_>>();
1386        assert_eq!(
1387            fold_ranges,
1388            vec![
1389                Point::new(0, 2)..Point::new(2, 2),
1390                Point::new(1, 2)..Point::new(3, 2)
1391            ]
1392        );
1393    }
1394
1395    #[gpui::test(iterations = 100)]
1396    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1397        let operations = env::var("OPERATIONS")
1398            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1399            .unwrap_or(10);
1400
1401        let len = rng.gen_range(0..10);
1402        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1403        let buffer = if rng.gen() {
1404            MultiBuffer::build_simple(&text, cx)
1405        } else {
1406            MultiBuffer::build_random(&mut rng, cx)
1407        };
1408        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1409        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1410
1411        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1412        let mut snapshot_edits = Vec::new();
1413
1414        let mut highlights = TreeMap::default();
1415        let highlight_count = rng.gen_range(0_usize..10);
1416        let mut highlight_ranges = (0..highlight_count)
1417            .map(|_| buffer_snapshot.random_byte_range(0, &mut rng))
1418            .collect::<Vec<_>>();
1419        highlight_ranges.sort_by_key(|range| (range.start, Reverse(range.end)));
1420        log::info!("highlighting ranges {:?}", highlight_ranges);
1421        let highlight_ranges = highlight_ranges
1422            .into_iter()
1423            .map(|range| {
1424                buffer_snapshot.anchor_before(range.start)..buffer_snapshot.anchor_after(range.end)
1425            })
1426            .collect::<Vec<_>>();
1427
1428        highlights.insert(
1429            Some(TypeId::of::<()>()),
1430            Arc::new((HighlightStyle::default(), highlight_ranges)),
1431        );
1432
1433        for _ in 0..operations {
1434            log::info!("text: {:?}", buffer_snapshot.text());
1435            let mut buffer_edits = Vec::new();
1436            match rng.gen_range(0..=100) {
1437                0..=59 => {
1438                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1439                }
1440                _ => buffer.update(cx, |buffer, cx| {
1441                    let subscription = buffer.subscribe();
1442                    let edit_count = rng.gen_range(1..=5);
1443                    buffer.randomly_mutate(&mut rng, edit_count, cx);
1444                    buffer_snapshot = buffer.snapshot(cx);
1445                    let edits = subscription.consume().into_inner();
1446                    log::info!("editing {:?}", edits);
1447                    buffer_edits.extend(edits);
1448                }),
1449            };
1450
1451            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1452            snapshot_edits.push((snapshot.clone(), edits));
1453
1454            let mut expected_text: String = buffer_snapshot.text().to_string();
1455            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1456                expected_text.replace_range(fold_range.start..fold_range.end, "…");
1457            }
1458
1459            assert_eq!(snapshot.text(), expected_text);
1460            log::info!(
1461                "fold text {:?} ({} lines)",
1462                expected_text,
1463                expected_text.matches('\n').count() + 1
1464            );
1465
1466            let mut prev_row = 0;
1467            let mut expected_buffer_rows = Vec::new();
1468            for fold_range in map.merged_fold_ranges().into_iter() {
1469                let fold_start = buffer_snapshot.offset_to_point(fold_range.start).row;
1470                let fold_end = buffer_snapshot.offset_to_point(fold_range.end).row;
1471                expected_buffer_rows.extend(
1472                    buffer_snapshot
1473                        .buffer_rows(prev_row)
1474                        .take((1 + fold_start - prev_row) as usize),
1475                );
1476                prev_row = 1 + fold_end;
1477            }
1478            expected_buffer_rows.extend(buffer_snapshot.buffer_rows(prev_row));
1479
1480            assert_eq!(
1481                expected_buffer_rows.len(),
1482                expected_text.matches('\n').count() + 1,
1483                "wrong expected buffer rows {:?}. text: {:?}",
1484                expected_buffer_rows,
1485                expected_text
1486            );
1487
1488            for (output_row, line) in expected_text.lines().enumerate() {
1489                let line_len = snapshot.line_len(output_row as u32);
1490                assert_eq!(line_len, line.len() as u32);
1491            }
1492
1493            let longest_row = snapshot.longest_row();
1494            let longest_char_column = expected_text
1495                .split('\n')
1496                .nth(longest_row as usize)
1497                .unwrap()
1498                .chars()
1499                .count();
1500            let mut fold_point = FoldPoint::new(0, 0);
1501            let mut fold_offset = FoldOffset(0);
1502            let mut char_column = 0;
1503            for c in expected_text.chars() {
1504                let buffer_point = fold_point.to_buffer_point(&snapshot);
1505                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1506                assert_eq!(
1507                    snapshot.to_fold_point(buffer_point, Right),
1508                    fold_point,
1509                    "{:?} -> fold point",
1510                    buffer_point,
1511                );
1512                assert_eq!(
1513                    fold_point.to_buffer_offset(&snapshot),
1514                    buffer_offset,
1515                    "fold_point.to_buffer_offset({:?})",
1516                    fold_point,
1517                );
1518                assert_eq!(
1519                    fold_point.to_offset(&snapshot),
1520                    fold_offset,
1521                    "fold_point.to_offset({:?})",
1522                    fold_point,
1523                );
1524
1525                if c == '\n' {
1526                    *fold_point.row_mut() += 1;
1527                    *fold_point.column_mut() = 0;
1528                    char_column = 0;
1529                } else {
1530                    *fold_point.column_mut() += c.len_utf8() as u32;
1531                    char_column += 1;
1532                }
1533                fold_offset.0 += c.len_utf8();
1534                if char_column > longest_char_column {
1535                    panic!(
1536                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1537                        longest_row,
1538                        longest_char_column,
1539                        fold_point.row(),
1540                        char_column
1541                    );
1542                }
1543            }
1544
1545            for _ in 0..5 {
1546                let mut start = snapshot
1547                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1548                let mut end = snapshot
1549                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1550                if start > end {
1551                    mem::swap(&mut start, &mut end);
1552                }
1553
1554                let text = &expected_text[start.0..end.0];
1555                assert_eq!(
1556                    snapshot
1557                        .chunks(start..end, false, Some(&highlights))
1558                        .map(|c| c.text)
1559                        .collect::<String>(),
1560                    text,
1561                );
1562            }
1563
1564            let mut fold_row = 0;
1565            while fold_row < expected_buffer_rows.len() as u32 {
1566                fold_row = snapshot
1567                    .clip_point(FoldPoint::new(fold_row, 0), Bias::Right)
1568                    .row();
1569                assert_eq!(
1570                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1571                    expected_buffer_rows[(fold_row as usize)..],
1572                    "wrong buffer rows starting at fold row {}",
1573                    fold_row,
1574                );
1575                fold_row += 1;
1576            }
1577
1578            for fold_range in map.merged_fold_ranges() {
1579                let fold_point =
1580                    snapshot.to_fold_point(fold_range.start.to_point(&buffer_snapshot), Right);
1581                assert!(snapshot.is_line_folded(fold_point.row()));
1582            }
1583
1584            for _ in 0..5 {
1585                let end =
1586                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1587                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1588                let expected_folds = map
1589                    .folds
1590                    .items(&buffer_snapshot)
1591                    .into_iter()
1592                    .filter(|fold| {
1593                        let start = buffer_snapshot.anchor_before(start);
1594                        let end = buffer_snapshot.anchor_after(end);
1595                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1596                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1597                                == Ordering::Greater
1598                    })
1599                    .map(|fold| fold.0)
1600                    .collect::<Vec<_>>();
1601
1602                assert_eq!(
1603                    snapshot
1604                        .folds_in_range(start..end)
1605                        .cloned()
1606                        .collect::<Vec<_>>(),
1607                    expected_folds
1608                );
1609            }
1610
1611            let text = snapshot.text();
1612            for _ in 0..5 {
1613                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1614                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1615                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1616                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1617                let mut start =
1618                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1619                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1620                if start > end {
1621                    mem::swap(&mut start, &mut end);
1622                }
1623
1624                let lines = start..end;
1625                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1626                assert_eq!(
1627                    snapshot.text_summary_for_range(lines),
1628                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1629                )
1630            }
1631
1632            let mut text = initial_snapshot.text();
1633            for (snapshot, edits) in snapshot_edits.drain(..) {
1634                let new_text = snapshot.text();
1635                for edit in edits {
1636                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1637                    let new_bytes = edit.new.start.0..edit.new.end.0;
1638                    text.replace_range(old_bytes, &new_text[new_bytes]);
1639                }
1640
1641                assert_eq!(text, new_text);
1642                initial_snapshot = snapshot;
1643            }
1644        }
1645    }
1646
1647    #[gpui::test]
1648    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1649        let text = sample_text(6, 6, 'a') + "\n";
1650        let buffer = MultiBuffer::build_simple(&text, cx);
1651
1652        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1653        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1654
1655        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1656        writer.fold(vec![
1657            Point::new(0, 2)..Point::new(2, 2),
1658            Point::new(3, 1)..Point::new(4, 1),
1659        ]);
1660
1661        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1662        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1663        assert_eq!(
1664            snapshot.buffer_rows(0).collect::<Vec<_>>(),
1665            [Some(0), Some(3), Some(5), Some(6)]
1666        );
1667        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [Some(6)]);
1668    }
1669
1670    impl FoldMap {
1671        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1672            let buffer = self.buffer.lock().clone();
1673            let mut folds = self.folds.items(&buffer);
1674            // Ensure sorting doesn't change how folds get merged and displayed.
1675            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1676            let mut fold_ranges = folds
1677                .iter()
1678                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1679                .peekable();
1680
1681            let mut merged_ranges = Vec::new();
1682            while let Some(mut fold_range) = fold_ranges.next() {
1683                while let Some(next_range) = fold_ranges.peek() {
1684                    if fold_range.end >= next_range.start {
1685                        if next_range.end > fold_range.end {
1686                            fold_range.end = next_range.end;
1687                        }
1688                        fold_ranges.next();
1689                    } else {
1690                        break;
1691                    }
1692                }
1693                if fold_range.end > fold_range.start {
1694                    merged_ranges.push(fold_range);
1695                }
1696            }
1697            merged_ranges
1698        }
1699
1700        pub fn randomly_mutate(
1701            &mut self,
1702            rng: &mut impl Rng,
1703        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1704            let mut snapshot_edits = Vec::new();
1705            match rng.gen_range(0..=100) {
1706                0..=39 if !self.folds.is_empty() => {
1707                    let buffer = self.buffer.lock().clone();
1708                    let mut to_unfold = Vec::new();
1709                    for _ in 0..rng.gen_range(1..=3) {
1710                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1711                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1712                        to_unfold.push(start..end);
1713                    }
1714                    log::info!("unfolding {:?}", to_unfold);
1715                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1716                    snapshot_edits.push((snapshot, edits));
1717                    let (snapshot, edits) = writer.fold(to_unfold);
1718                    snapshot_edits.push((snapshot, edits));
1719                }
1720                _ => {
1721                    let buffer = self.buffer.lock().clone();
1722                    let mut to_fold = Vec::new();
1723                    for _ in 0..rng.gen_range(1..=2) {
1724                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1725                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1726                        to_fold.push(start..end);
1727                    }
1728                    log::info!("folding {:?}", to_fold);
1729                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1730                    snapshot_edits.push((snapshot, edits));
1731                    let (snapshot, edits) = writer.fold(to_fold);
1732                    snapshot_edits.push((snapshot, edits));
1733                }
1734            }
1735            snapshot_edits
1736        }
1737    }
1738}