fold_map.rs

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