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