fold_map.rs

   1use language::{
   2    Anchor, AnchorRangeExt, Chunk, Edit, Point, PointUtf16, Snapshot as BufferSnapshot,
   3    TextSummary, ToOffset,
   4};
   5use parking_lot::Mutex;
   6use std::{
   7    cmp::{self, Ordering},
   8    iter,
   9    ops::Range,
  10    sync::atomic::{AtomicUsize, Ordering::SeqCst},
  11};
  12use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  13use theme::SyntaxTheme;
  14
  15pub trait ToFoldPoint {
  16    fn to_fold_point(&self, snapshot: &Snapshot, 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    #[cfg(test)]
  40    pub fn column_mut(&mut self) -> &mut u32 {
  41        &mut self.0.column
  42    }
  43
  44    pub fn to_buffer_point(&self, snapshot: &Snapshot) -> Point {
  45        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  46        cursor.seek(self, Bias::Right, &());
  47        let overshoot = self.0 - cursor.start().0 .0;
  48        cursor.start().1 + overshoot
  49    }
  50
  51    pub fn to_buffer_offset(&self, snapshot: &Snapshot) -> usize {
  52        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  53        cursor.seek(self, Bias::Right, &());
  54        let overshoot = self.0 - cursor.start().0 .0;
  55        snapshot
  56            .buffer_snapshot
  57            .to_offset(cursor.start().1 + overshoot)
  58    }
  59
  60    pub fn to_offset(&self, snapshot: &Snapshot) -> FoldOffset {
  61        let mut cursor = snapshot
  62            .transforms
  63            .cursor::<(FoldPoint, TransformSummary)>();
  64        cursor.seek(self, Bias::Right, &());
  65        let overshoot = self.0 - cursor.start().1.output.lines;
  66        let mut offset = cursor.start().1.output.bytes;
  67        if !overshoot.is_zero() {
  68            let transform = cursor.item().expect("display point out of range");
  69            assert!(transform.output_text.is_none());
  70            let end_buffer_offset = snapshot
  71                .buffer_snapshot
  72                .to_offset(cursor.start().1.input.lines + overshoot);
  73            offset += end_buffer_offset - cursor.start().1.input.bytes;
  74        }
  75        FoldOffset(offset)
  76    }
  77}
  78
  79impl ToFoldPoint for Point {
  80    fn to_fold_point(&self, snapshot: &Snapshot, bias: Bias) -> FoldPoint {
  81        let mut cursor = snapshot.transforms.cursor::<(Point, FoldPoint)>();
  82        cursor.seek(self, Bias::Right, &());
  83        if cursor.item().map_or(false, |t| t.is_fold()) {
  84            if bias == Bias::Left || *self == cursor.start().0 {
  85                cursor.start().1
  86            } else {
  87                cursor.end(&()).1
  88            }
  89        } else {
  90            let overshoot = *self - cursor.start().0;
  91            FoldPoint(cmp::min(
  92                cursor.start().1 .0 + overshoot,
  93                cursor.end(&()).1 .0,
  94            ))
  95        }
  96    }
  97}
  98
  99pub struct FoldMapWriter<'a>(&'a mut FoldMap);
 100
 101impl<'a> FoldMapWriter<'a> {
 102    pub fn fold<T: ToOffset>(
 103        &mut self,
 104        ranges: impl IntoIterator<Item = Range<T>>,
 105    ) -> (Snapshot, Vec<FoldEdit>) {
 106        let mut edits = Vec::new();
 107        let mut folds = Vec::new();
 108        let buffer = self.0.buffer.lock().clone();
 109        for range in ranges.into_iter() {
 110            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
 111            if range.start != range.end {
 112                let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 113                folds.push(fold);
 114                edits.push(text::Edit {
 115                    old: range.clone(),
 116                    new: range,
 117                });
 118            }
 119        }
 120
 121        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 122
 123        self.0.folds = {
 124            let mut new_tree = SumTree::new();
 125            let mut cursor = self.0.folds.cursor::<Fold>();
 126            for fold in folds {
 127                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 128                new_tree.push(fold, &buffer);
 129            }
 130            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 131            new_tree
 132        };
 133
 134        consolidate_buffer_edits(&mut edits);
 135        let edits = self.0.sync(buffer.clone(), edits);
 136        let snapshot = Snapshot {
 137            transforms: self.0.transforms.lock().clone(),
 138            folds: self.0.folds.clone(),
 139            buffer_snapshot: buffer,
 140            version: self.0.version.load(SeqCst),
 141        };
 142        (snapshot, edits)
 143    }
 144
 145    pub fn unfold<T: ToOffset>(
 146        &mut self,
 147        ranges: impl IntoIterator<Item = Range<T>>,
 148    ) -> (Snapshot, Vec<FoldEdit>) {
 149        let mut edits = Vec::new();
 150        let mut fold_ixs_to_delete = Vec::new();
 151        let buffer = self.0.buffer.lock().clone();
 152        for range in ranges.into_iter() {
 153            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 154            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 155            while let Some(fold) = folds_cursor.item() {
 156                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 157                edits.push(text::Edit {
 158                    old: offset_range.clone(),
 159                    new: offset_range,
 160                });
 161                fold_ixs_to_delete.push(*folds_cursor.start());
 162                folds_cursor.next(&buffer);
 163            }
 164        }
 165
 166        fold_ixs_to_delete.sort_unstable();
 167        fold_ixs_to_delete.dedup();
 168
 169        self.0.folds = {
 170            let mut cursor = self.0.folds.cursor::<usize>();
 171            let mut folds = SumTree::new();
 172            for fold_ix in fold_ixs_to_delete {
 173                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 174                cursor.next(&buffer);
 175            }
 176            folds.push_tree(cursor.suffix(&buffer), &buffer);
 177            folds
 178        };
 179
 180        consolidate_buffer_edits(&mut edits);
 181        let edits = self.0.sync(buffer.clone(), edits);
 182        let snapshot = Snapshot {
 183            transforms: self.0.transforms.lock().clone(),
 184            folds: self.0.folds.clone(),
 185            buffer_snapshot: buffer,
 186            version: self.0.version.load(SeqCst),
 187        };
 188        (snapshot, edits)
 189    }
 190}
 191
 192pub struct FoldMap {
 193    buffer: Mutex<BufferSnapshot>,
 194    transforms: Mutex<SumTree<Transform>>,
 195    folds: SumTree<Fold>,
 196    version: AtomicUsize,
 197}
 198
 199impl FoldMap {
 200    pub fn new(buffer: BufferSnapshot) -> (Self, Snapshot) {
 201        let this = Self {
 202            buffer: Mutex::new(buffer.clone()),
 203            folds: Default::default(),
 204            transforms: Mutex::new(SumTree::from_item(
 205                Transform {
 206                    summary: TransformSummary {
 207                        input: buffer.text_summary(),
 208                        output: buffer.text_summary(),
 209                    },
 210                    output_text: None,
 211                },
 212                &(),
 213            )),
 214            version: Default::default(),
 215        };
 216
 217        let snapshot = Snapshot {
 218            transforms: this.transforms.lock().clone(),
 219            folds: this.folds.clone(),
 220            buffer_snapshot: this.buffer.lock().clone(),
 221            version: this.version.load(SeqCst),
 222        };
 223        (this, snapshot)
 224    }
 225
 226    pub fn read(
 227        &self,
 228        buffer: BufferSnapshot,
 229        edits: Vec<Edit<usize>>,
 230    ) -> (Snapshot, Vec<FoldEdit>) {
 231        let edits = self.sync(buffer, edits);
 232        self.check_invariants();
 233        let snapshot = Snapshot {
 234            transforms: self.transforms.lock().clone(),
 235            folds: self.folds.clone(),
 236            buffer_snapshot: self.buffer.lock().clone(),
 237            version: self.version.load(SeqCst),
 238        };
 239        (snapshot, edits)
 240    }
 241
 242    pub fn write(
 243        &mut self,
 244        buffer: BufferSnapshot,
 245        edits: Vec<Edit<usize>>,
 246    ) -> (FoldMapWriter, Snapshot, Vec<FoldEdit>) {
 247        let (snapshot, edits) = self.read(buffer, edits);
 248        (FoldMapWriter(self), snapshot, edits)
 249    }
 250
 251    fn check_invariants(&self) {
 252        if cfg!(test) {
 253            assert_eq!(
 254                self.transforms.lock().summary().input.bytes,
 255                self.buffer.lock().len(),
 256                "transform tree does not match buffer's length"
 257            );
 258        }
 259    }
 260
 261    fn sync(
 262        &self,
 263        new_buffer: BufferSnapshot,
 264        buffer_edits: Vec<text::Edit<usize>>,
 265    ) -> Vec<FoldEdit> {
 266        if buffer_edits.is_empty() {
 267            let mut buffer = self.buffer.lock();
 268            if buffer.parse_count() != new_buffer.parse_count()
 269                || buffer.diagnostics_update_count() != new_buffer.diagnostics_update_count()
 270            {
 271                self.version.fetch_add(1, SeqCst);
 272            }
 273            *buffer = new_buffer;
 274            Vec::new()
 275        } else {
 276            let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 277
 278            let mut new_transforms = SumTree::new();
 279            let mut transforms = self.transforms.lock();
 280            let mut cursor = transforms.cursor::<usize>();
 281            cursor.seek(&0, Bias::Right, &());
 282
 283            while let Some(mut edit) = buffer_edits_iter.next() {
 284                new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 285                edit.new.start -= edit.old.start - cursor.start();
 286                edit.old.start = *cursor.start();
 287
 288                cursor.seek(&edit.old.end, Bias::Right, &());
 289                cursor.next(&());
 290
 291                let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 292                loop {
 293                    edit.old.end = *cursor.start();
 294
 295                    if let Some(next_edit) = buffer_edits_iter.peek() {
 296                        if next_edit.old.start > edit.old.end {
 297                            break;
 298                        }
 299
 300                        let next_edit = buffer_edits_iter.next().unwrap();
 301                        delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 302
 303                        if next_edit.old.end >= edit.old.end {
 304                            edit.old.end = next_edit.old.end;
 305                            cursor.seek(&edit.old.end, Bias::Right, &());
 306                            cursor.next(&());
 307                        }
 308                    } else {
 309                        break;
 310                    }
 311                }
 312
 313                edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 314
 315                let anchor = new_buffer.anchor_before(edit.new.start);
 316                let mut folds_cursor = self.folds.cursor::<Fold>();
 317                folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &new_buffer);
 318
 319                let mut folds = iter::from_fn({
 320                    let buffer = &new_buffer;
 321                    move || {
 322                        let item = folds_cursor
 323                            .item()
 324                            .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 325                        folds_cursor.next(buffer);
 326                        item
 327                    }
 328                })
 329                .peekable();
 330
 331                while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 332                    let mut fold = folds.next().unwrap();
 333                    let sum = new_transforms.summary();
 334
 335                    assert!(fold.start >= sum.input.bytes);
 336
 337                    while folds
 338                        .peek()
 339                        .map_or(false, |next_fold| next_fold.start <= fold.end)
 340                    {
 341                        let next_fold = folds.next().unwrap();
 342                        if next_fold.end > fold.end {
 343                            fold.end = next_fold.end;
 344                        }
 345                    }
 346
 347                    if fold.start > sum.input.bytes {
 348                        let text_summary = new_buffer
 349                            .text_summary_for_range::<TextSummary, _>(sum.input.bytes..fold.start);
 350                        new_transforms.push(
 351                            Transform {
 352                                summary: TransformSummary {
 353                                    output: text_summary.clone(),
 354                                    input: text_summary,
 355                                },
 356                                output_text: None,
 357                            },
 358                            &(),
 359                        );
 360                    }
 361
 362                    if fold.end > fold.start {
 363                        let output_text = "";
 364                        let chars = output_text.chars().count() as u32;
 365                        let lines = Point::new(0, output_text.len() as u32);
 366                        let lines_utf16 =
 367                            PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 368                        new_transforms.push(
 369                            Transform {
 370                                summary: TransformSummary {
 371                                    output: TextSummary {
 372                                        bytes: output_text.len(),
 373                                        lines,
 374                                        lines_utf16,
 375                                        first_line_chars: chars,
 376                                        last_line_chars: chars,
 377                                        longest_row: 0,
 378                                        longest_row_chars: chars,
 379                                    },
 380                                    input: new_buffer.text_summary_for_range(fold.start..fold.end),
 381                                },
 382                                output_text: Some(output_text),
 383                            },
 384                            &(),
 385                        );
 386                    }
 387                }
 388
 389                let sum = new_transforms.summary();
 390                if sum.input.bytes < edit.new.end {
 391                    let text_summary = new_buffer
 392                        .text_summary_for_range::<TextSummary, _>(sum.input.bytes..edit.new.end);
 393                    new_transforms.push(
 394                        Transform {
 395                            summary: TransformSummary {
 396                                output: text_summary.clone(),
 397                                input: text_summary,
 398                            },
 399                            output_text: None,
 400                        },
 401                        &(),
 402                    );
 403                }
 404            }
 405
 406            new_transforms.push_tree(cursor.suffix(&()), &());
 407            if new_transforms.is_empty() {
 408                let text_summary = new_buffer.text_summary();
 409                new_transforms.push(
 410                    Transform {
 411                        summary: TransformSummary {
 412                            output: text_summary.clone(),
 413                            input: text_summary,
 414                        },
 415                        output_text: None,
 416                    },
 417                    &(),
 418                );
 419            }
 420
 421            drop(cursor);
 422
 423            let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 424            {
 425                let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 426                let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 427
 428                for mut edit in buffer_edits {
 429                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 430                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 431                        edit.old.start = old_transforms.start().0;
 432                    }
 433                    let old_start =
 434                        old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 435
 436                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 437                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 438                        old_transforms.next(&());
 439                        edit.old.end = old_transforms.start().0;
 440                    }
 441                    let old_end =
 442                        old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 443
 444                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 445                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 446                        edit.new.start = new_transforms.start().0;
 447                    }
 448                    let new_start =
 449                        new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 450
 451                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 452                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 453                        new_transforms.next(&());
 454                        edit.new.end = new_transforms.start().0;
 455                    }
 456                    let new_end =
 457                        new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 458
 459                    fold_edits.push(FoldEdit {
 460                        old_bytes: FoldOffset(old_start)..FoldOffset(old_end),
 461                        new_bytes: FoldOffset(new_start)..FoldOffset(new_end),
 462                    });
 463                }
 464
 465                consolidate_fold_edits(&mut fold_edits);
 466            }
 467
 468            *transforms = new_transforms;
 469            *self.buffer.lock() = new_buffer;
 470            self.version.fetch_add(1, SeqCst);
 471            fold_edits
 472        }
 473    }
 474}
 475
 476#[derive(Clone)]
 477pub struct Snapshot {
 478    transforms: SumTree<Transform>,
 479    folds: SumTree<Fold>,
 480    buffer_snapshot: language::Snapshot,
 481    pub version: usize,
 482}
 483
 484impl Snapshot {
 485    #[cfg(test)]
 486    pub fn text(&self) -> String {
 487        self.chunks(FoldOffset(0)..self.len(), None)
 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 len(&self) -> FoldOffset {
 542        FoldOffset(self.transforms.summary().output.bytes)
 543    }
 544
 545    #[cfg(test)]
 546    pub fn line_len(&self, row: u32) -> u32 {
 547        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 548        let line_end = if row >= self.max_point().row() {
 549            self.len().0
 550        } else {
 551            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 552        };
 553        (line_end - line_start) as u32
 554    }
 555
 556    pub fn buffer_rows(&self, start_row: u32) -> BufferRows {
 557        if start_row > self.transforms.summary().output.lines.row {
 558            panic!("invalid display row {}", start_row);
 559        }
 560
 561        let fold_point = FoldPoint::new(start_row, 0);
 562        let mut cursor = self.transforms.cursor();
 563        cursor.seek(&fold_point, Bias::Left, &());
 564        BufferRows { fold_point, cursor }
 565    }
 566
 567    pub fn max_point(&self) -> FoldPoint {
 568        FoldPoint(self.transforms.summary().output.lines)
 569    }
 570
 571    #[cfg(test)]
 572    pub fn longest_row(&self) -> u32 {
 573        self.transforms.summary().output.longest_row
 574    }
 575
 576    pub fn folds_in_range<'a, T>(
 577        &'a self,
 578        range: Range<T>,
 579    ) -> impl Iterator<Item = &'a Range<Anchor>>
 580    where
 581        T: ToOffset,
 582    {
 583        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 584        iter::from_fn(move || {
 585            let item = folds.item().map(|f| &f.0);
 586            folds.next(&self.buffer_snapshot);
 587            item
 588        })
 589    }
 590
 591    pub fn intersects_fold<T>(&self, offset: T) -> bool
 592    where
 593        T: ToOffset,
 594    {
 595        let offset = offset.to_offset(&self.buffer_snapshot);
 596        let mut cursor = self.transforms.cursor::<usize>();
 597        cursor.seek(&offset, Bias::Right, &());
 598        cursor.item().map_or(false, |t| t.output_text.is_some())
 599    }
 600
 601    pub fn is_line_folded(&self, output_row: u32) -> bool {
 602        let mut cursor = self.transforms.cursor::<FoldPoint>();
 603        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 604        while let Some(transform) = cursor.item() {
 605            if transform.output_text.is_some() {
 606                return true;
 607            }
 608            if cursor.end(&()).row() == output_row {
 609                cursor.next(&())
 610            } else {
 611                break;
 612            }
 613        }
 614        false
 615    }
 616
 617    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 618        let start = start.to_offset(self);
 619        self.chunks(start..self.len(), None)
 620            .flat_map(|chunk| chunk.text.chars())
 621    }
 622
 623    pub fn chunks<'a>(
 624        &'a self,
 625        range: Range<FoldOffset>,
 626        theme: Option<&'a SyntaxTheme>,
 627    ) -> Chunks<'a> {
 628        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 629
 630        transform_cursor.seek(&range.end, Bias::Right, &());
 631        let overshoot = range.end.0 - transform_cursor.start().0 .0;
 632        let buffer_end = transform_cursor.start().1 + overshoot;
 633
 634        transform_cursor.seek(&range.start, Bias::Right, &());
 635        let overshoot = range.start.0 - transform_cursor.start().0 .0;
 636        let buffer_start = transform_cursor.start().1 + overshoot;
 637
 638        Chunks {
 639            transform_cursor,
 640            buffer_chunks: self.buffer_snapshot.chunks(buffer_start..buffer_end, theme),
 641            buffer_chunk: None,
 642            buffer_offset: buffer_start,
 643            output_offset: range.start.0,
 644            max_output_offset: range.end.0,
 645        }
 646    }
 647
 648    #[cfg(test)]
 649    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 650        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 651        cursor.seek(&offset, Bias::Right, &());
 652        if let Some(transform) = cursor.item() {
 653            let transform_start = cursor.start().0 .0;
 654            if transform.output_text.is_some() {
 655                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 656                    FoldOffset(transform_start)
 657                } else {
 658                    FoldOffset(cursor.end(&()).0 .0)
 659                }
 660            } else {
 661                let overshoot = offset.0 - transform_start;
 662                let buffer_offset = cursor.start().1 + overshoot;
 663                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 664                FoldOffset(
 665                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 666                        as usize,
 667                )
 668            }
 669        } else {
 670            FoldOffset(self.transforms.summary().output.bytes)
 671        }
 672    }
 673
 674    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 675        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 676        cursor.seek(&point, Bias::Right, &());
 677        if let Some(transform) = cursor.item() {
 678            let transform_start = cursor.start().0 .0;
 679            if transform.output_text.is_some() {
 680                if point.0 == transform_start || matches!(bias, Bias::Left) {
 681                    FoldPoint(transform_start)
 682                } else {
 683                    FoldPoint(cursor.end(&()).0 .0)
 684                }
 685            } else {
 686                let overshoot = point.0 - transform_start;
 687                let buffer_position = cursor.start().1 + overshoot;
 688                let clipped_buffer_position =
 689                    self.buffer_snapshot.clip_point(buffer_position, bias);
 690                FoldPoint::new(
 691                    point.row(),
 692                    ((point.column() as i32) + clipped_buffer_position.column as i32
 693                        - buffer_position.column as i32) as u32,
 694                )
 695            }
 696        } else {
 697            FoldPoint(self.transforms.summary().output.lines)
 698        }
 699    }
 700}
 701
 702fn intersecting_folds<'a, T>(
 703    buffer: &'a text::Snapshot,
 704    folds: &'a SumTree<Fold>,
 705    range: Range<T>,
 706    inclusive: bool,
 707) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 708where
 709    T: ToOffset,
 710{
 711    let start = buffer.anchor_before(range.start.to_offset(buffer));
 712    let end = buffer.anchor_after(range.end.to_offset(buffer));
 713    folds.filter::<_, usize>(
 714        move |summary| {
 715            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 716            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 717
 718            if inclusive {
 719                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 720            } else {
 721                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 722            }
 723        },
 724        buffer,
 725    )
 726}
 727
 728fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 729    edits.sort_unstable_by(|a, b| {
 730        a.old
 731            .start
 732            .cmp(&b.old.start)
 733            .then_with(|| b.old.end.cmp(&a.old.end))
 734    });
 735
 736    let mut i = 1;
 737    while i < edits.len() {
 738        let edit = edits[i].clone();
 739        let prev_edit = &mut edits[i - 1];
 740        if prev_edit.old.end >= edit.old.start {
 741            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 742            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 743            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 744            edits.remove(i);
 745            continue;
 746        }
 747        i += 1;
 748    }
 749}
 750
 751fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 752    edits.sort_unstable_by(|a, b| {
 753        a.old_bytes
 754            .start
 755            .cmp(&b.old_bytes.start)
 756            .then_with(|| b.old_bytes.end.cmp(&a.old_bytes.end))
 757    });
 758
 759    let mut i = 1;
 760    while i < edits.len() {
 761        let edit = edits[i].clone();
 762        let prev_edit = &mut edits[i - 1];
 763        if prev_edit.old_bytes.end >= edit.old_bytes.start {
 764            prev_edit.old_bytes.end = prev_edit.old_bytes.end.max(edit.old_bytes.end);
 765            prev_edit.new_bytes.start = prev_edit.new_bytes.start.min(edit.new_bytes.start);
 766            prev_edit.new_bytes.end = prev_edit.new_bytes.end.max(edit.new_bytes.end);
 767            edits.remove(i);
 768            continue;
 769        }
 770        i += 1;
 771    }
 772}
 773
 774#[derive(Clone, Debug, Default, Eq, PartialEq)]
 775struct Transform {
 776    summary: TransformSummary,
 777    output_text: Option<&'static str>,
 778}
 779
 780impl Transform {
 781    fn is_fold(&self) -> bool {
 782        self.output_text.is_some()
 783    }
 784}
 785
 786#[derive(Clone, Debug, Default, Eq, PartialEq)]
 787struct TransformSummary {
 788    output: TextSummary,
 789    input: TextSummary,
 790}
 791
 792impl sum_tree::Item for Transform {
 793    type Summary = TransformSummary;
 794
 795    fn summary(&self) -> Self::Summary {
 796        self.summary.clone()
 797    }
 798}
 799
 800impl sum_tree::Summary for TransformSummary {
 801    type Context = ();
 802
 803    fn add_summary(&mut self, other: &Self, _: &()) {
 804        self.input += &other.input;
 805        self.output += &other.output;
 806    }
 807}
 808
 809#[derive(Clone, Debug)]
 810struct Fold(Range<Anchor>);
 811
 812impl Default for Fold {
 813    fn default() -> Self {
 814        Self(Anchor::min()..Anchor::max())
 815    }
 816}
 817
 818impl sum_tree::Item for Fold {
 819    type Summary = FoldSummary;
 820
 821    fn summary(&self) -> Self::Summary {
 822        FoldSummary {
 823            start: self.0.start.clone(),
 824            end: self.0.end.clone(),
 825            min_start: self.0.start.clone(),
 826            max_end: self.0.end.clone(),
 827            count: 1,
 828        }
 829    }
 830}
 831
 832#[derive(Clone, Debug)]
 833struct FoldSummary {
 834    start: Anchor,
 835    end: Anchor,
 836    min_start: Anchor,
 837    max_end: Anchor,
 838    count: usize,
 839}
 840
 841impl Default for FoldSummary {
 842    fn default() -> Self {
 843        Self {
 844            start: Anchor::min(),
 845            end: Anchor::max(),
 846            min_start: Anchor::max(),
 847            max_end: Anchor::min(),
 848            count: 0,
 849        }
 850    }
 851}
 852
 853impl sum_tree::Summary for FoldSummary {
 854    type Context = text::Snapshot;
 855
 856    fn add_summary(&mut self, other: &Self, buffer: &text::Snapshot) {
 857        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 858            self.min_start = other.min_start.clone();
 859        }
 860        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 861            self.max_end = other.max_end.clone();
 862        }
 863
 864        #[cfg(debug_assertions)]
 865        {
 866            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 867            assert!(start_comparison <= Ordering::Equal);
 868            if start_comparison == Ordering::Equal {
 869                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 870            }
 871        }
 872
 873        self.start = other.start.clone();
 874        self.end = other.end.clone();
 875        self.count += other.count;
 876    }
 877}
 878
 879impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 880    fn add_summary(&mut self, summary: &'a FoldSummary, _: &text::Snapshot) {
 881        self.0.start = summary.start.clone();
 882        self.0.end = summary.end.clone();
 883    }
 884}
 885
 886impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 887    fn cmp(&self, other: &Self, buffer: &text::Snapshot) -> Ordering {
 888        self.0.cmp(&other.0, buffer).unwrap()
 889    }
 890}
 891
 892impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 893    fn add_summary(&mut self, summary: &'a FoldSummary, _: &text::Snapshot) {
 894        *self += summary.count;
 895    }
 896}
 897
 898pub struct BufferRows<'a> {
 899    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 900    fold_point: FoldPoint,
 901}
 902
 903impl<'a> Iterator for BufferRows<'a> {
 904    type Item = u32;
 905
 906    fn next(&mut self) -> Option<Self::Item> {
 907        while self.fold_point > self.cursor.end(&()).0 {
 908            self.cursor.next(&());
 909            if self.cursor.item().is_none() {
 910                // TODO: Return a bool from next?
 911                break;
 912            }
 913        }
 914
 915        if self.cursor.item().is_some() {
 916            let overshoot = self.fold_point.0 - self.cursor.start().0 .0;
 917            let buffer_point = self.cursor.start().1 + overshoot;
 918            *self.fold_point.row_mut() += 1;
 919            Some(buffer_point.row)
 920        } else {
 921            None
 922        }
 923    }
 924}
 925
 926pub struct Chunks<'a> {
 927    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 928    buffer_chunks: language::Chunks<'a>,
 929    buffer_chunk: Option<(usize, Chunk<'a>)>,
 930    buffer_offset: usize,
 931    output_offset: usize,
 932    max_output_offset: usize,
 933}
 934
 935impl<'a> Iterator for Chunks<'a> {
 936    type Item = Chunk<'a>;
 937
 938    fn next(&mut self) -> Option<Self::Item> {
 939        if self.output_offset >= self.max_output_offset {
 940            return None;
 941        }
 942
 943        let transform = if let Some(item) = self.transform_cursor.item() {
 944            item
 945        } else {
 946            return None;
 947        };
 948
 949        // If we're in a fold, then return the fold's display text and
 950        // advance the transform and buffer cursors to the end of the fold.
 951        if let Some(output_text) = transform.output_text {
 952            self.buffer_chunk.take();
 953            self.buffer_offset += transform.summary.input.bytes;
 954            self.buffer_chunks.seek(self.buffer_offset);
 955
 956            while self.buffer_offset >= self.transform_cursor.end(&()).1
 957                && self.transform_cursor.item().is_some()
 958            {
 959                self.transform_cursor.next(&());
 960            }
 961
 962            self.output_offset += output_text.len();
 963            return Some(Chunk {
 964                text: output_text,
 965                highlight_style: None,
 966                diagnostic: None,
 967            });
 968        }
 969
 970        // Retrieve a chunk from the current location in the buffer.
 971        if self.buffer_chunk.is_none() {
 972            let chunk_offset = self.buffer_chunks.offset();
 973            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
 974        }
 975
 976        // Otherwise, take a chunk from the buffer's text.
 977        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
 978            let offset_in_chunk = self.buffer_offset - chunk_offset;
 979            chunk.text = &chunk.text[offset_in_chunk..];
 980
 981            // Truncate the chunk so that it ends at the next fold.
 982            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 983            if chunk.text.len() >= region_end {
 984                chunk.text = &chunk.text[0..region_end];
 985                self.transform_cursor.next(&());
 986            } else {
 987                self.buffer_chunk.take();
 988            }
 989
 990            self.buffer_offset += chunk.text.len();
 991            self.output_offset += chunk.text.len();
 992            return Some(chunk);
 993        }
 994
 995        None
 996    }
 997}
 998
 999impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1000    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1001        self.0 += &summary.output.lines;
1002    }
1003}
1004
1005#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1006pub struct FoldOffset(pub usize);
1007
1008impl FoldOffset {
1009    pub fn to_point(&self, snapshot: &Snapshot) -> FoldPoint {
1010        let mut cursor = snapshot
1011            .transforms
1012            .cursor::<(FoldOffset, TransformSummary)>();
1013        cursor.seek(self, Bias::Right, &());
1014        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1015            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1016        } else {
1017            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1018            let buffer_point = snapshot.buffer_snapshot.to_point(buffer_offset);
1019            buffer_point - cursor.start().1.input.lines
1020        };
1021        FoldPoint(cursor.start().1.output.lines + overshoot)
1022    }
1023}
1024
1025impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1026    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1027        self.0 += &summary.output.bytes;
1028    }
1029}
1030
1031impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1032    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1033        *self += &summary.input.lines;
1034    }
1035}
1036
1037impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1038    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1039        *self += &summary.input.bytes;
1040    }
1041}
1042
1043#[derive(Clone, Debug, PartialEq, Eq)]
1044pub struct FoldEdit {
1045    pub old_bytes: Range<FoldOffset>,
1046    pub new_bytes: Range<FoldOffset>,
1047}
1048
1049#[cfg(test)]
1050impl FoldEdit {
1051    pub fn delta(&self) -> isize {
1052        self.inserted_bytes() as isize - self.deleted_bytes() as isize
1053    }
1054
1055    pub fn deleted_bytes(&self) -> usize {
1056        self.old_bytes.end.0 - self.old_bytes.start.0
1057    }
1058
1059    pub fn inserted_bytes(&self) -> usize {
1060        self.new_bytes.end.0 - self.new_bytes.start.0
1061    }
1062}
1063
1064#[cfg(test)]
1065mod tests {
1066    use super::*;
1067    use crate::{test::sample_text, ToPoint};
1068    use language::Buffer;
1069    use rand::prelude::*;
1070    use std::{env, mem};
1071    use text::RandomCharIter;
1072    use Bias::{Left, Right};
1073
1074    #[gpui::test]
1075    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1076        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1077        let buffer_snapshot = buffer.read(cx).snapshot();
1078        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1079
1080        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1081        let (snapshot2, edits) = writer.fold(vec![
1082            Point::new(0, 2)..Point::new(2, 2),
1083            Point::new(2, 4)..Point::new(4, 1),
1084        ]);
1085        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1086        assert_eq!(
1087            edits,
1088            &[
1089                FoldEdit {
1090                    old_bytes: FoldOffset(2)..FoldOffset(16),
1091                    new_bytes: FoldOffset(2)..FoldOffset(5),
1092                },
1093                FoldEdit {
1094                    old_bytes: FoldOffset(18)..FoldOffset(29),
1095                    new_bytes: FoldOffset(7)..FoldOffset(10)
1096                },
1097            ]
1098        );
1099
1100        let (buffer_snapshot, edits) = buffer.update(cx, |buffer, cx| {
1101            let v0 = buffer.version();
1102            buffer.edit(
1103                vec![
1104                    Point::new(0, 0)..Point::new(0, 1),
1105                    Point::new(2, 3)..Point::new(2, 3),
1106                ],
1107                "123",
1108                cx,
1109            );
1110            (buffer.snapshot(), buffer.edits_since(&v0).collect())
1111        });
1112        let (snapshot3, edits) = map.read(buffer_snapshot.clone(), edits);
1113        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1114        assert_eq!(
1115            edits,
1116            &[
1117                FoldEdit {
1118                    old_bytes: FoldOffset(0)..FoldOffset(1),
1119                    new_bytes: FoldOffset(0)..FoldOffset(3),
1120                },
1121                FoldEdit {
1122                    old_bytes: FoldOffset(6)..FoldOffset(6),
1123                    new_bytes: FoldOffset(8)..FoldOffset(11),
1124                },
1125            ]
1126        );
1127
1128        let (buffer_snapshot, edits) = buffer.update(cx, |buffer, cx| {
1129            let v0 = buffer.version();
1130            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1131            (buffer.snapshot(), buffer.edits_since(&v0).collect())
1132        });
1133        let (snapshot4, _) = map.read(buffer_snapshot.clone(), edits);
1134        assert_eq!(snapshot4.text(), "123a…c123456eee");
1135
1136        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1137        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1138        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1139        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1140    }
1141
1142    #[gpui::test]
1143    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1144        let buffer = cx.add_model(|cx| Buffer::new(0, "abcdefghijkl", cx));
1145        let buffer_snapshot = buffer.read(cx).snapshot();
1146
1147        {
1148            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1149
1150            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1151            writer.fold(vec![5..8]);
1152            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1153            assert_eq!(snapshot.text(), "abcde…ijkl");
1154
1155            // Create an fold adjacent to the start of the first fold.
1156            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1157            writer.fold(vec![0..1, 2..5]);
1158            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1159            assert_eq!(snapshot.text(), "…b…ijkl");
1160
1161            // Create an fold adjacent to the end of the first fold.
1162            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1163            writer.fold(vec![11..11, 8..10]);
1164            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1165            assert_eq!(snapshot.text(), "…b…kl");
1166        }
1167
1168        {
1169            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1170
1171            // Create two adjacent folds.
1172            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1173            writer.fold(vec![0..2, 2..5]);
1174            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1175            assert_eq!(snapshot.text(), "…fghijkl");
1176
1177            // Edit within one of the folds.
1178            let (buffer_snapshot, edits) = buffer.update(cx, |buffer, cx| {
1179                let v0 = buffer.version();
1180                buffer.edit(vec![0..1], "12345", cx);
1181                (buffer.snapshot(), buffer.edits_since(&v0).collect())
1182            });
1183            let (snapshot, _) = map.read(buffer_snapshot.clone(), edits);
1184            assert_eq!(snapshot.text(), "12345…fghijkl");
1185        }
1186    }
1187
1188    #[gpui::test]
1189    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1190        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1191        let buffer_snapshot = buffer.read(cx).snapshot();
1192        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1193        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1194        writer.fold(vec![
1195            Point::new(0, 2)..Point::new(2, 2),
1196            Point::new(0, 4)..Point::new(1, 0),
1197            Point::new(1, 2)..Point::new(3, 2),
1198            Point::new(3, 1)..Point::new(4, 1),
1199        ]);
1200        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1201        assert_eq!(snapshot.text(), "aa…eeeee");
1202    }
1203
1204    #[gpui::test]
1205    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1206        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1207        let buffer_snapshot = buffer.read(cx).snapshot();
1208        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1209
1210        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1211        writer.fold(vec![
1212            Point::new(0, 2)..Point::new(2, 2),
1213            Point::new(3, 1)..Point::new(4, 1),
1214        ]);
1215        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1216        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1217
1218        let (buffer_snapshot, edits) = buffer.update(cx, |buffer, cx| {
1219            let v0 = buffer.version();
1220            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1221            (buffer.snapshot(), buffer.edits_since(&v0).collect())
1222        });
1223        let (snapshot, _) = map.read(buffer_snapshot.clone(), edits);
1224        assert_eq!(snapshot.text(), "aa…eeeee");
1225    }
1226
1227    #[gpui::test]
1228    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1229        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1230        let buffer_snapshot = buffer.read(cx).snapshot();
1231        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1232        let buffer = buffer.read(cx);
1233
1234        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1235        writer.fold(vec![
1236            Point::new(0, 2)..Point::new(2, 2),
1237            Point::new(0, 4)..Point::new(1, 0),
1238            Point::new(1, 2)..Point::new(3, 2),
1239            Point::new(3, 1)..Point::new(4, 1),
1240        ]);
1241        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1242        let fold_ranges = snapshot
1243            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1244            .map(|fold| fold.start.to_point(buffer)..fold.end.to_point(buffer))
1245            .collect::<Vec<_>>();
1246        assert_eq!(
1247            fold_ranges,
1248            vec![
1249                Point::new(0, 2)..Point::new(2, 2),
1250                Point::new(1, 2)..Point::new(3, 2)
1251            ]
1252        );
1253    }
1254
1255    #[gpui::test(iterations = 100)]
1256    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1257        let operations = env::var("OPERATIONS")
1258            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1259            .unwrap_or(10);
1260
1261        let buffer = cx.add_model(|cx| {
1262            let len = rng.gen_range(0..10);
1263            let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1264            Buffer::new(0, text, cx)
1265        });
1266        let buffer_snapshot = buffer.read(cx).snapshot();
1267        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1268
1269        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1270        let mut snapshot_edits = Vec::new();
1271
1272        for _ in 0..operations {
1273            log::info!("text: {:?}", buffer.read(cx).text());
1274            let buffer_edits = match rng.gen_range(0..=100) {
1275                0..=59 => {
1276                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1277                    vec![]
1278                }
1279                _ => buffer.update(cx, |buffer, cx| {
1280                    let start_version = buffer.version.clone();
1281                    let edit_count = rng.gen_range(1..=5);
1282                    buffer.randomly_edit(&mut rng, edit_count, cx);
1283                    let edits = buffer
1284                        .edits_since::<Point>(&start_version)
1285                        .collect::<Vec<_>>();
1286                    log::info!("editing {:?}", edits);
1287                    buffer.edits_since::<usize>(&start_version).collect()
1288                }),
1289            };
1290            let buffer_snapshot = buffer.read(cx).snapshot();
1291
1292            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1293            snapshot_edits.push((snapshot.clone(), edits));
1294
1295            let mut expected_text: String = buffer_snapshot.text().to_string();
1296            let mut expected_buffer_rows = Vec::new();
1297            let mut next_row = buffer_snapshot.max_point().row;
1298            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1299                let fold_start = buffer_snapshot.point_for_offset(fold_range.start).unwrap();
1300                let fold_end = buffer_snapshot.point_for_offset(fold_range.end).unwrap();
1301                expected_buffer_rows.extend((fold_end.row + 1..=next_row).rev());
1302                next_row = fold_start.row;
1303
1304                expected_text.replace_range(fold_range.start..fold_range.end, "");
1305            }
1306            expected_buffer_rows.extend((0..=next_row).rev());
1307            expected_buffer_rows.reverse();
1308
1309            assert_eq!(snapshot.text(), expected_text);
1310
1311            for (output_row, line) in expected_text.lines().enumerate() {
1312                let line_len = snapshot.line_len(output_row as u32);
1313                assert_eq!(line_len, line.len() as u32);
1314            }
1315
1316            let longest_row = snapshot.longest_row();
1317            let longest_char_column = expected_text
1318                .split('\n')
1319                .nth(longest_row as usize)
1320                .unwrap()
1321                .chars()
1322                .count();
1323            let mut fold_point = FoldPoint::new(0, 0);
1324            let mut fold_offset = FoldOffset(0);
1325            let mut char_column = 0;
1326            for c in expected_text.chars() {
1327                let buffer_point = fold_point.to_buffer_point(&snapshot);
1328                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1329                assert_eq!(
1330                    buffer_point.to_fold_point(&snapshot, Right),
1331                    fold_point,
1332                    "{:?} -> fold point",
1333                    buffer_point,
1334                );
1335                assert_eq!(
1336                    fold_point.to_buffer_offset(&snapshot),
1337                    buffer_offset,
1338                    "fold_point.to_buffer_offset({:?})",
1339                    fold_point,
1340                );
1341                assert_eq!(
1342                    fold_point.to_offset(&snapshot),
1343                    fold_offset,
1344                    "fold_point.to_offset({:?})",
1345                    fold_point,
1346                );
1347
1348                if c == '\n' {
1349                    *fold_point.row_mut() += 1;
1350                    *fold_point.column_mut() = 0;
1351                    char_column = 0;
1352                } else {
1353                    *fold_point.column_mut() += c.len_utf8() as u32;
1354                    char_column += 1;
1355                }
1356                fold_offset.0 += c.len_utf8();
1357                if char_column > longest_char_column {
1358                    panic!(
1359                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1360                        longest_row,
1361                        longest_char_column,
1362                        fold_point.row(),
1363                        char_column
1364                    );
1365                }
1366            }
1367
1368            for _ in 0..5 {
1369                let mut start = snapshot
1370                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1371                let mut end = snapshot
1372                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1373                if start > end {
1374                    mem::swap(&mut start, &mut end);
1375                }
1376
1377                let text = &expected_text[start.0..end.0];
1378                log::info!("slicing {:?}..{:?} (text: {:?})", start, end, text);
1379                assert_eq!(
1380                    snapshot
1381                        .chunks(start..end, None)
1382                        .map(|c| c.text)
1383                        .collect::<String>(),
1384                    text,
1385                );
1386            }
1387
1388            for (idx, buffer_row) in expected_buffer_rows.iter().enumerate() {
1389                let fold_row = Point::new(*buffer_row, 0)
1390                    .to_fold_point(&snapshot, Right)
1391                    .row();
1392                assert_eq!(
1393                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1394                    expected_buffer_rows[idx..],
1395                );
1396            }
1397
1398            for fold_range in map.merged_fold_ranges() {
1399                let fold_point = fold_range
1400                    .start
1401                    .to_point(&buffer_snapshot)
1402                    .to_fold_point(&snapshot, Right);
1403                assert!(snapshot.is_line_folded(fold_point.row()));
1404            }
1405
1406            for _ in 0..5 {
1407                let end =
1408                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1409                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1410                let expected_folds = map
1411                    .folds
1412                    .items(&buffer_snapshot)
1413                    .into_iter()
1414                    .filter(|fold| {
1415                        let start = buffer_snapshot.anchor_before(start);
1416                        let end = buffer_snapshot.anchor_after(end);
1417                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1418                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1419                                == Ordering::Greater
1420                    })
1421                    .map(|fold| fold.0)
1422                    .collect::<Vec<_>>();
1423
1424                assert_eq!(
1425                    snapshot
1426                        .folds_in_range(start..end)
1427                        .cloned()
1428                        .collect::<Vec<_>>(),
1429                    expected_folds
1430                );
1431            }
1432
1433            let text = snapshot.text();
1434            for _ in 0..5 {
1435                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1436                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1437                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1438                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1439                let mut start =
1440                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1441                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1442                if start > end {
1443                    mem::swap(&mut start, &mut end);
1444                }
1445
1446                let lines = start..end;
1447                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1448                assert_eq!(
1449                    snapshot.text_summary_for_range(lines),
1450                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1451                )
1452            }
1453
1454            let mut text = initial_snapshot.text();
1455            for (snapshot, edits) in snapshot_edits.drain(..) {
1456                let new_text = snapshot.text();
1457                let mut delta = 0isize;
1458                for edit in edits {
1459                    let old_bytes = ((edit.old_bytes.start.0 as isize) + delta) as usize
1460                        ..((edit.old_bytes.end.0 as isize) + delta) as usize;
1461                    let new_bytes = edit.new_bytes.start.0..edit.new_bytes.end.0;
1462                    delta += edit.delta();
1463                    text.replace_range(old_bytes, &new_text[new_bytes]);
1464                }
1465
1466                assert_eq!(text, new_text);
1467                initial_snapshot = snapshot;
1468            }
1469        }
1470    }
1471
1472    #[gpui::test]
1473    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1474        let text = sample_text(6, 6) + "\n";
1475        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
1476
1477        let buffer_snapshot = buffer.read(cx).snapshot();
1478        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1479
1480        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1481        writer.fold(vec![
1482            Point::new(0, 2)..Point::new(2, 2),
1483            Point::new(3, 1)..Point::new(4, 1),
1484        ]);
1485
1486        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1487        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1488        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), [0, 3, 5, 6]);
1489        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [6]);
1490    }
1491
1492    impl FoldMap {
1493        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1494            let buffer = self.buffer.lock().clone();
1495            let mut folds = self.folds.items(&buffer);
1496            // Ensure sorting doesn't change how folds get merged and displayed.
1497            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1498            let mut fold_ranges = folds
1499                .iter()
1500                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1501                .peekable();
1502
1503            let mut merged_ranges = Vec::new();
1504            while let Some(mut fold_range) = fold_ranges.next() {
1505                while let Some(next_range) = fold_ranges.peek() {
1506                    if fold_range.end >= next_range.start {
1507                        if next_range.end > fold_range.end {
1508                            fold_range.end = next_range.end;
1509                        }
1510                        fold_ranges.next();
1511                    } else {
1512                        break;
1513                    }
1514                }
1515                if fold_range.end > fold_range.start {
1516                    merged_ranges.push(fold_range);
1517                }
1518            }
1519            merged_ranges
1520        }
1521
1522        pub fn randomly_mutate(&mut self, rng: &mut impl Rng) -> Vec<(Snapshot, Vec<FoldEdit>)> {
1523            let mut snapshot_edits = Vec::new();
1524            match rng.gen_range(0..=100) {
1525                0..=39 if !self.folds.is_empty() => {
1526                    let buffer = self.buffer.lock().clone();
1527                    let mut to_unfold = Vec::new();
1528                    for _ in 0..rng.gen_range(1..=3) {
1529                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1530                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1531                        to_unfold.push(start..end);
1532                    }
1533                    log::info!("unfolding {:?}", to_unfold);
1534                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1535                    snapshot_edits.push((snapshot, edits));
1536                    let (snapshot, edits) = writer.fold(to_unfold);
1537                    snapshot_edits.push((snapshot, edits));
1538                }
1539                _ => {
1540                    let buffer = self.buffer.lock().clone();
1541                    let mut to_fold = Vec::new();
1542                    for _ in 0..rng.gen_range(1..=2) {
1543                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1544                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1545                        to_fold.push(start..end);
1546                    }
1547                    log::info!("folding {:?}", to_fold);
1548                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1549                    snapshot_edits.push((snapshot, edits));
1550                    let (snapshot, edits) = writer.fold(to_fold);
1551                    snapshot_edits.push((snapshot, edits));
1552                }
1553            }
1554            snapshot_edits
1555        }
1556    }
1557}