fold_map.rs

   1use language::{
   2    multi_buffer::{Anchor, AnchorRangeExt, MultiBufferChunks, MultiBufferSnapshot, ToOffset},
   3    Chunk, Edit, Point, PointUtf16, TextSummary,
   4};
   5use parking_lot::Mutex;
   6use std::{
   7    cmp::{self, Ordering},
   8    iter,
   9    ops::{Range, Sub},
  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: &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    #[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: &FoldSnapshot) -> Point {
  45        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  46        cursor.seek(self, Bias::Right, &());
  47        let overshoot = self.0 - cursor.start().0 .0;
  48        cursor.start().1 + overshoot
  49    }
  50
  51    pub fn to_buffer_offset(&self, snapshot: &FoldSnapshot) -> usize {
  52        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  53        cursor.seek(self, Bias::Right, &());
  54        let overshoot = self.0 - cursor.start().0 .0;
  55        snapshot
  56            .buffer_snapshot
  57            .point_to_offset(cursor.start().1 + overshoot)
  58    }
  59
  60    pub fn to_offset(&self, snapshot: &FoldSnapshot) -> FoldOffset {
  61        let mut cursor = snapshot
  62            .transforms
  63            .cursor::<(FoldPoint, TransformSummary)>();
  64        cursor.seek(self, Bias::Right, &());
  65        let overshoot = self.0 - cursor.start().1.output.lines;
  66        let mut offset = cursor.start().1.output.bytes;
  67        if !overshoot.is_zero() {
  68            let transform = cursor.item().expect("display point out of range");
  69            assert!(transform.output_text.is_none());
  70            let end_buffer_offset = snapshot
  71                .buffer_snapshot
  72                .point_to_offset(cursor.start().1.input.lines + overshoot);
  73            offset += end_buffer_offset - cursor.start().1.input.bytes;
  74        }
  75        FoldOffset(offset)
  76    }
  77}
  78
  79impl ToFoldPoint for Point {
  80    fn to_fold_point(&self, snapshot: &FoldSnapshot, 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    ) -> (FoldSnapshot, 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 = FoldSnapshot {
 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    ) -> (FoldSnapshot, 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 = FoldSnapshot {
 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<MultiBufferSnapshot>,
 194    transforms: Mutex<SumTree<Transform>>,
 195    folds: SumTree<Fold>,
 196    version: AtomicUsize,
 197}
 198
 199impl FoldMap {
 200    pub fn new(buffer: MultiBufferSnapshot) -> (Self, FoldSnapshot) {
 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 = FoldSnapshot {
 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: MultiBufferSnapshot,
 229        edits: Vec<Edit<usize>>,
 230    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 231        let edits = self.sync(buffer, edits);
 232        self.check_invariants();
 233        let snapshot = FoldSnapshot {
 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: MultiBufferSnapshot,
 245        edits: Vec<Edit<usize>>,
 246    ) -> (FoldMapWriter, FoldSnapshot, 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: MultiBufferSnapshot,
 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: FoldOffset(old_start)..FoldOffset(old_end),
 461                        new: 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 FoldSnapshot {
 478    transforms: SumTree<Transform>,
 479    folds: SumTree<Fold>,
 480    buffer_snapshot: MultiBufferSnapshot,
 481    pub version: usize,
 482}
 483
 484impl FoldSnapshot {
 485    pub fn buffer_snapshot(&self) -> &MultiBufferSnapshot {
 486        &self.buffer_snapshot
 487    }
 488
 489    #[cfg(test)]
 490    pub fn text(&self) -> String {
 491        self.chunks(FoldOffset(0)..self.len(), None)
 492            .map(|c| c.text)
 493            .collect()
 494    }
 495
 496    #[cfg(test)]
 497    pub fn fold_count(&self) -> usize {
 498        self.folds.items(&self.buffer_snapshot).len()
 499    }
 500
 501    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 502        let mut summary = TextSummary::default();
 503
 504        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 505        cursor.seek(&range.start, Bias::Right, &());
 506        if let Some(transform) = cursor.item() {
 507            let start_in_transform = range.start.0 - cursor.start().0 .0;
 508            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 509            if let Some(output_text) = transform.output_text {
 510                summary = TextSummary::from(
 511                    &output_text
 512                        [start_in_transform.column as usize..end_in_transform.column as usize],
 513                );
 514            } else {
 515                let buffer_start = cursor.start().1 + start_in_transform;
 516                let buffer_end = cursor.start().1 + end_in_transform;
 517                summary = self
 518                    .buffer_snapshot
 519                    .text_summary_for_range(buffer_start..buffer_end);
 520            }
 521        }
 522
 523        if range.end > cursor.end(&()).0 {
 524            cursor.next(&());
 525            summary += &cursor
 526                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 527                .output;
 528            if let Some(transform) = cursor.item() {
 529                let end_in_transform = range.end.0 - cursor.start().0 .0;
 530                if let Some(output_text) = transform.output_text {
 531                    summary += TextSummary::from(&output_text[..end_in_transform.column as usize]);
 532                } else {
 533                    let buffer_start = cursor.start().1;
 534                    let buffer_end = cursor.start().1 + end_in_transform;
 535                    summary += self
 536                        .buffer_snapshot
 537                        .text_summary_for_range::<TextSummary, _>(buffer_start..buffer_end);
 538                }
 539            }
 540        }
 541
 542        summary
 543    }
 544
 545    pub fn len(&self) -> FoldOffset {
 546        FoldOffset(self.transforms.summary().output.bytes)
 547    }
 548
 549    #[cfg(test)]
 550    pub fn line_len(&self, row: u32) -> u32 {
 551        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 552        let line_end = if row >= self.max_point().row() {
 553            self.len().0
 554        } else {
 555            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 556        };
 557        (line_end - line_start) as u32
 558    }
 559
 560    pub fn buffer_rows(&self, start_row: u32) -> FoldBufferRows {
 561        if start_row > self.transforms.summary().output.lines.row {
 562            panic!("invalid display row {}", start_row);
 563        }
 564
 565        let fold_point = FoldPoint::new(start_row, 0);
 566        let mut cursor = self.transforms.cursor();
 567        cursor.seek(&fold_point, Bias::Left, &());
 568        FoldBufferRows { fold_point, cursor }
 569    }
 570
 571    pub fn max_point(&self) -> FoldPoint {
 572        FoldPoint(self.transforms.summary().output.lines)
 573    }
 574
 575    #[cfg(test)]
 576    pub fn longest_row(&self) -> u32 {
 577        self.transforms.summary().output.longest_row
 578    }
 579
 580    pub fn folds_in_range<'a, T>(
 581        &'a self,
 582        range: Range<T>,
 583    ) -> impl Iterator<Item = &'a Range<Anchor>>
 584    where
 585        T: ToOffset,
 586    {
 587        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 588        iter::from_fn(move || {
 589            let item = folds.item().map(|f| &f.0);
 590            folds.next(&self.buffer_snapshot);
 591            item
 592        })
 593    }
 594
 595    pub fn intersects_fold<T>(&self, offset: T) -> bool
 596    where
 597        T: ToOffset,
 598    {
 599        let offset = offset.to_offset(&self.buffer_snapshot);
 600        let mut cursor = self.transforms.cursor::<usize>();
 601        cursor.seek(&offset, Bias::Right, &());
 602        cursor.item().map_or(false, |t| t.output_text.is_some())
 603    }
 604
 605    pub fn is_line_folded(&self, output_row: u32) -> bool {
 606        let mut cursor = self.transforms.cursor::<FoldPoint>();
 607        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 608        while let Some(transform) = cursor.item() {
 609            if transform.output_text.is_some() {
 610                return true;
 611            }
 612            if cursor.end(&()).row() == output_row {
 613                cursor.next(&())
 614            } else {
 615                break;
 616            }
 617        }
 618        false
 619    }
 620
 621    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 622        let start = start.to_offset(self);
 623        self.chunks(start..self.len(), None)
 624            .flat_map(|chunk| chunk.text.chars())
 625    }
 626
 627    pub fn chunks<'a>(
 628        &'a self,
 629        range: Range<FoldOffset>,
 630        theme: Option<&'a SyntaxTheme>,
 631    ) -> FoldChunks<'a> {
 632        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 633
 634        transform_cursor.seek(&range.end, Bias::Right, &());
 635        let overshoot = range.end.0 - transform_cursor.start().0 .0;
 636        let buffer_end = transform_cursor.start().1 + overshoot;
 637
 638        transform_cursor.seek(&range.start, Bias::Right, &());
 639        let overshoot = range.start.0 - transform_cursor.start().0 .0;
 640        let buffer_start = transform_cursor.start().1 + overshoot;
 641
 642        FoldChunks {
 643            transform_cursor,
 644            buffer_chunks: self.buffer_snapshot.chunks(buffer_start..buffer_end, theme),
 645            buffer_chunk: None,
 646            buffer_offset: buffer_start,
 647            output_offset: range.start.0,
 648            max_output_offset: range.end.0,
 649        }
 650    }
 651
 652    #[cfg(test)]
 653    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 654        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 655        cursor.seek(&offset, Bias::Right, &());
 656        if let Some(transform) = cursor.item() {
 657            let transform_start = cursor.start().0 .0;
 658            if transform.output_text.is_some() {
 659                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 660                    FoldOffset(transform_start)
 661                } else {
 662                    FoldOffset(cursor.end(&()).0 .0)
 663                }
 664            } else {
 665                let overshoot = offset.0 - transform_start;
 666                let buffer_offset = cursor.start().1 + overshoot;
 667                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 668                FoldOffset(
 669                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 670                        as usize,
 671                )
 672            }
 673        } else {
 674            FoldOffset(self.transforms.summary().output.bytes)
 675        }
 676    }
 677
 678    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 679        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 680        cursor.seek(&point, Bias::Right, &());
 681        if let Some(transform) = cursor.item() {
 682            let transform_start = cursor.start().0 .0;
 683            if transform.output_text.is_some() {
 684                if point.0 == transform_start || matches!(bias, Bias::Left) {
 685                    FoldPoint(transform_start)
 686                } else {
 687                    FoldPoint(cursor.end(&()).0 .0)
 688                }
 689            } else {
 690                let overshoot = point.0 - transform_start;
 691                let buffer_position = cursor.start().1 + overshoot;
 692                let clipped_buffer_position =
 693                    self.buffer_snapshot.clip_point(buffer_position, bias);
 694                FoldPoint::new(
 695                    point.row(),
 696                    ((point.column() as i32) + clipped_buffer_position.column as i32
 697                        - buffer_position.column as i32) as u32,
 698                )
 699            }
 700        } else {
 701            FoldPoint(self.transforms.summary().output.lines)
 702        }
 703    }
 704}
 705
 706fn intersecting_folds<'a, T>(
 707    buffer: &'a MultiBufferSnapshot,
 708    folds: &'a SumTree<Fold>,
 709    range: Range<T>,
 710    inclusive: bool,
 711) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 712where
 713    T: ToOffset,
 714{
 715    let start = buffer.anchor_before(range.start.to_offset(buffer));
 716    let end = buffer.anchor_after(range.end.to_offset(buffer));
 717    folds.filter::<_, usize>(
 718        move |summary| {
 719            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 720            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 721
 722            if inclusive {
 723                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 724            } else {
 725                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 726            }
 727        },
 728        buffer,
 729    )
 730}
 731
 732fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 733    edits.sort_unstable_by(|a, b| {
 734        a.old
 735            .start
 736            .cmp(&b.old.start)
 737            .then_with(|| b.old.end.cmp(&a.old.end))
 738    });
 739
 740    let mut i = 1;
 741    while i < edits.len() {
 742        let edit = edits[i].clone();
 743        let prev_edit = &mut edits[i - 1];
 744        if prev_edit.old.end >= edit.old.start {
 745            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 746            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 747            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 748            edits.remove(i);
 749            continue;
 750        }
 751        i += 1;
 752    }
 753}
 754
 755fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 756    edits.sort_unstable_by(|a, b| {
 757        a.old
 758            .start
 759            .cmp(&b.old.start)
 760            .then_with(|| b.old.end.cmp(&a.old.end))
 761    });
 762
 763    let mut i = 1;
 764    while i < edits.len() {
 765        let edit = edits[i].clone();
 766        let prev_edit = &mut edits[i - 1];
 767        if prev_edit.old.end >= edit.old.start {
 768            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 769            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 770            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 771            edits.remove(i);
 772            continue;
 773        }
 774        i += 1;
 775    }
 776}
 777
 778#[derive(Clone, Debug, Default, Eq, PartialEq)]
 779struct Transform {
 780    summary: TransformSummary,
 781    output_text: Option<&'static str>,
 782}
 783
 784impl Transform {
 785    fn is_fold(&self) -> bool {
 786        self.output_text.is_some()
 787    }
 788}
 789
 790#[derive(Clone, Debug, Default, Eq, PartialEq)]
 791struct TransformSummary {
 792    output: TextSummary,
 793    input: TextSummary,
 794}
 795
 796impl sum_tree::Item for Transform {
 797    type Summary = TransformSummary;
 798
 799    fn summary(&self) -> Self::Summary {
 800        self.summary.clone()
 801    }
 802}
 803
 804impl sum_tree::Summary for TransformSummary {
 805    type Context = ();
 806
 807    fn add_summary(&mut self, other: &Self, _: &()) {
 808        self.input += &other.input;
 809        self.output += &other.output;
 810    }
 811}
 812
 813#[derive(Clone, Debug)]
 814struct Fold(Range<Anchor>);
 815
 816impl Default for Fold {
 817    fn default() -> Self {
 818        Self(Anchor::min()..Anchor::max())
 819    }
 820}
 821
 822impl sum_tree::Item for Fold {
 823    type Summary = FoldSummary;
 824
 825    fn summary(&self) -> Self::Summary {
 826        FoldSummary {
 827            start: self.0.start.clone(),
 828            end: self.0.end.clone(),
 829            min_start: self.0.start.clone(),
 830            max_end: self.0.end.clone(),
 831            count: 1,
 832        }
 833    }
 834}
 835
 836#[derive(Clone, Debug)]
 837struct FoldSummary {
 838    start: Anchor,
 839    end: Anchor,
 840    min_start: Anchor,
 841    max_end: Anchor,
 842    count: usize,
 843}
 844
 845impl Default for FoldSummary {
 846    fn default() -> Self {
 847        Self {
 848            start: Anchor::min(),
 849            end: Anchor::max(),
 850            min_start: Anchor::max(),
 851            max_end: Anchor::min(),
 852            count: 0,
 853        }
 854    }
 855}
 856
 857impl sum_tree::Summary for FoldSummary {
 858    type Context = MultiBufferSnapshot;
 859
 860    fn add_summary(&mut self, other: &Self, buffer: &MultiBufferSnapshot) {
 861        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 862            self.min_start = other.min_start.clone();
 863        }
 864        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 865            self.max_end = other.max_end.clone();
 866        }
 867
 868        #[cfg(debug_assertions)]
 869        {
 870            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 871            assert!(start_comparison <= Ordering::Equal);
 872            if start_comparison == Ordering::Equal {
 873                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 874            }
 875        }
 876
 877        self.start = other.start.clone();
 878        self.end = other.end.clone();
 879        self.count += other.count;
 880    }
 881}
 882
 883impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 884    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 885        self.0.start = summary.start.clone();
 886        self.0.end = summary.end.clone();
 887    }
 888}
 889
 890impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 891    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
 892        self.0.cmp(&other.0, buffer).unwrap()
 893    }
 894}
 895
 896impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 897    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 898        *self += summary.count;
 899    }
 900}
 901
 902pub struct FoldBufferRows<'a> {
 903    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 904    fold_point: FoldPoint,
 905}
 906
 907impl<'a> Iterator for FoldBufferRows<'a> {
 908    type Item = u32;
 909
 910    fn next(&mut self) -> Option<Self::Item> {
 911        while self.fold_point > self.cursor.end(&()).0 {
 912            self.cursor.next(&());
 913            if self.cursor.item().is_none() {
 914                // TODO: Return a bool from next?
 915                break;
 916            }
 917        }
 918
 919        if self.cursor.item().is_some() {
 920            let overshoot = self.fold_point.0 - self.cursor.start().0 .0;
 921            let buffer_point = self.cursor.start().1 + overshoot;
 922            *self.fold_point.row_mut() += 1;
 923            Some(buffer_point.row)
 924        } else {
 925            None
 926        }
 927    }
 928}
 929
 930pub struct FoldChunks<'a> {
 931    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 932    buffer_chunks: MultiBufferChunks<'a>,
 933    buffer_chunk: Option<(usize, Chunk<'a>)>,
 934    buffer_offset: usize,
 935    output_offset: usize,
 936    max_output_offset: usize,
 937}
 938
 939impl<'a> Iterator for FoldChunks<'a> {
 940    type Item = Chunk<'a>;
 941
 942    fn next(&mut self) -> Option<Self::Item> {
 943        if self.output_offset >= self.max_output_offset {
 944            return None;
 945        }
 946
 947        let transform = if let Some(item) = self.transform_cursor.item() {
 948            item
 949        } else {
 950            return None;
 951        };
 952
 953        // If we're in a fold, then return the fold's display text and
 954        // advance the transform and buffer cursors to the end of the fold.
 955        if let Some(output_text) = transform.output_text {
 956            self.buffer_chunk.take();
 957            self.buffer_offset += transform.summary.input.bytes;
 958            self.buffer_chunks.seek(self.buffer_offset);
 959
 960            while self.buffer_offset >= self.transform_cursor.end(&()).1
 961                && self.transform_cursor.item().is_some()
 962            {
 963                self.transform_cursor.next(&());
 964            }
 965
 966            self.output_offset += output_text.len();
 967            return Some(Chunk {
 968                text: output_text,
 969                highlight_style: None,
 970                diagnostic: None,
 971            });
 972        }
 973
 974        // Retrieve a chunk from the current location in the buffer.
 975        if self.buffer_chunk.is_none() {
 976            let chunk_offset = self.buffer_chunks.offset();
 977            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
 978        }
 979
 980        // Otherwise, take a chunk from the buffer's text.
 981        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
 982            let offset_in_chunk = self.buffer_offset - chunk_offset;
 983            chunk.text = &chunk.text[offset_in_chunk..];
 984
 985            // Truncate the chunk so that it ends at the next fold.
 986            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 987            if chunk.text.len() >= region_end {
 988                chunk.text = &chunk.text[0..region_end];
 989                self.transform_cursor.next(&());
 990            } else {
 991                self.buffer_chunk.take();
 992            }
 993
 994            self.buffer_offset += chunk.text.len();
 995            self.output_offset += chunk.text.len();
 996            return Some(chunk);
 997        }
 998
 999        None
1000    }
1001}
1002
1003impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1004    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1005        self.0 += &summary.output.lines;
1006    }
1007}
1008
1009#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1010pub struct FoldOffset(pub usize);
1011
1012impl FoldOffset {
1013    pub fn to_point(&self, snapshot: &FoldSnapshot) -> FoldPoint {
1014        let mut cursor = snapshot
1015            .transforms
1016            .cursor::<(FoldOffset, TransformSummary)>();
1017        cursor.seek(self, Bias::Right, &());
1018        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1019            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1020        } else {
1021            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1022            let buffer_point = snapshot.buffer_snapshot.offset_to_point(buffer_offset);
1023            buffer_point - cursor.start().1.input.lines
1024        };
1025        FoldPoint(cursor.start().1.output.lines + overshoot)
1026    }
1027}
1028
1029impl Sub for FoldOffset {
1030    type Output = Self;
1031
1032    fn sub(self, rhs: Self) -> Self::Output {
1033        Self(self.0 - rhs.0)
1034    }
1035}
1036
1037impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1038    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1039        self.0 += &summary.output.bytes;
1040    }
1041}
1042
1043impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1044    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1045        *self += &summary.input.lines;
1046    }
1047}
1048
1049impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1050    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1051        *self += &summary.input.bytes;
1052    }
1053}
1054
1055pub type FoldEdit = Edit<FoldOffset>;
1056
1057#[cfg(test)]
1058mod tests {
1059    use super::*;
1060    use crate::ToPoint;
1061    use language::multi_buffer::MultiBuffer;
1062    use rand::prelude::*;
1063    use std::{env, mem};
1064    use text::RandomCharIter;
1065    use util::test::sample_text;
1066    use Bias::{Left, Right};
1067
1068    #[gpui::test]
1069    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1070        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1071        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1072        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1073        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1074
1075        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1076        let (snapshot2, edits) = writer.fold(vec![
1077            Point::new(0, 2)..Point::new(2, 2),
1078            Point::new(2, 4)..Point::new(4, 1),
1079        ]);
1080        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1081        assert_eq!(
1082            edits,
1083            &[
1084                FoldEdit {
1085                    old: FoldOffset(2)..FoldOffset(16),
1086                    new: FoldOffset(2)..FoldOffset(5),
1087                },
1088                FoldEdit {
1089                    old: FoldOffset(18)..FoldOffset(29),
1090                    new: FoldOffset(7)..FoldOffset(10)
1091                },
1092            ]
1093        );
1094
1095        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1096            buffer.edit(
1097                vec![
1098                    Point::new(0, 0)..Point::new(0, 1),
1099                    Point::new(2, 3)..Point::new(2, 3),
1100                ],
1101                "123",
1102                cx,
1103            );
1104            buffer.snapshot(cx)
1105        });
1106        let (snapshot3, edits) =
1107            map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1108        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1109        assert_eq!(
1110            edits,
1111            &[
1112                FoldEdit {
1113                    old: FoldOffset(0)..FoldOffset(1),
1114                    new: FoldOffset(0)..FoldOffset(3),
1115                },
1116                FoldEdit {
1117                    old: FoldOffset(6)..FoldOffset(6),
1118                    new: FoldOffset(8)..FoldOffset(11),
1119                },
1120            ]
1121        );
1122
1123        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1124            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1125            buffer.snapshot(cx)
1126        });
1127        let (snapshot4, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1128        assert_eq!(snapshot4.text(), "123a…c123456eee");
1129
1130        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1131        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1132        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1133        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1134    }
1135
1136    #[gpui::test]
1137    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1138        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1139        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1140        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1141
1142        {
1143            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1144
1145            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1146            writer.fold(vec![5..8]);
1147            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1148            assert_eq!(snapshot.text(), "abcde…ijkl");
1149
1150            // Create an fold adjacent to the start of the first fold.
1151            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1152            writer.fold(vec![0..1, 2..5]);
1153            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1154            assert_eq!(snapshot.text(), "…b…ijkl");
1155
1156            // Create an fold adjacent to the end of the first fold.
1157            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1158            writer.fold(vec![11..11, 8..10]);
1159            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1160            assert_eq!(snapshot.text(), "…b…kl");
1161        }
1162
1163        {
1164            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1165
1166            // Create two adjacent folds.
1167            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1168            writer.fold(vec![0..2, 2..5]);
1169            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1170            assert_eq!(snapshot.text(), "…fghijkl");
1171
1172            // Edit within one of the folds.
1173            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1174                buffer.edit(vec![0..1], "12345", cx);
1175                buffer.snapshot(cx)
1176            });
1177            let (snapshot, _) =
1178                map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1179            assert_eq!(snapshot.text(), "12345…fghijkl");
1180        }
1181    }
1182
1183    #[gpui::test]
1184    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1185        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1186        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1187        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1188        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1189        writer.fold(vec![
1190            Point::new(0, 2)..Point::new(2, 2),
1191            Point::new(0, 4)..Point::new(1, 0),
1192            Point::new(1, 2)..Point::new(3, 2),
1193            Point::new(3, 1)..Point::new(4, 1),
1194        ]);
1195        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1196        assert_eq!(snapshot.text(), "aa…eeeee");
1197    }
1198
1199    #[gpui::test]
1200    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1201        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1202        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1203        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1204        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1205
1206        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1207        writer.fold(vec![
1208            Point::new(0, 2)..Point::new(2, 2),
1209            Point::new(3, 1)..Point::new(4, 1),
1210        ]);
1211        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1212        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1213
1214        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1215            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1216            buffer.snapshot(cx)
1217        });
1218        let (snapshot, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1219        assert_eq!(snapshot.text(), "aa…eeeee");
1220    }
1221
1222    #[gpui::test]
1223    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1224        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1225        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1226        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1227
1228        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1229        writer.fold(vec![
1230            Point::new(0, 2)..Point::new(2, 2),
1231            Point::new(0, 4)..Point::new(1, 0),
1232            Point::new(1, 2)..Point::new(3, 2),
1233            Point::new(3, 1)..Point::new(4, 1),
1234        ]);
1235        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1236        let fold_ranges = snapshot
1237            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1238            .map(|fold| fold.start.to_point(&buffer_snapshot)..fold.end.to_point(&buffer_snapshot))
1239            .collect::<Vec<_>>();
1240        assert_eq!(
1241            fold_ranges,
1242            vec![
1243                Point::new(0, 2)..Point::new(2, 2),
1244                Point::new(1, 2)..Point::new(3, 2)
1245            ]
1246        );
1247    }
1248
1249    #[gpui::test(iterations = 100)]
1250    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1251        let operations = env::var("OPERATIONS")
1252            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1253            .unwrap_or(10);
1254
1255        let len = rng.gen_range(0..10);
1256        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1257        let buffer = MultiBuffer::build_simple(&text, cx);
1258        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1259        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1260
1261        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1262        let mut snapshot_edits = Vec::new();
1263
1264        for _ in 0..operations {
1265            log::info!("text: {:?}", buffer_snapshot.text());
1266            let mut buffer_edits = Vec::new();
1267            match rng.gen_range(0..=100) {
1268                0..=59 => {
1269                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1270                }
1271                _ => buffer.update(cx, |buffer, cx| {
1272                    let subscription = buffer.subscribe();
1273                    let edit_count = rng.gen_range(1..=5);
1274                    buffer.randomly_edit(&mut rng, edit_count, cx);
1275                    let edits = subscription.consume().into_inner();
1276                    log::info!("editing {:?}", edits);
1277                    buffer_edits.extend(edits);
1278                }),
1279            };
1280            buffer_snapshot = buffer.read(cx).snapshot(cx);
1281
1282            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1283            snapshot_edits.push((snapshot.clone(), edits));
1284
1285            let mut expected_text: String = buffer_snapshot.text().to_string();
1286            let mut expected_buffer_rows = Vec::new();
1287            let mut next_row = buffer_snapshot.max_point().row;
1288            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1289                let fold_start = buffer_snapshot.offset_to_point(fold_range.start);
1290                let fold_end = buffer_snapshot.offset_to_point(fold_range.end);
1291                expected_buffer_rows.extend((fold_end.row + 1..=next_row).rev());
1292                next_row = fold_start.row;
1293
1294                expected_text.replace_range(fold_range.start..fold_range.end, "");
1295            }
1296            expected_buffer_rows.extend((0..=next_row).rev());
1297            expected_buffer_rows.reverse();
1298
1299            assert_eq!(snapshot.text(), expected_text);
1300
1301            for (output_row, line) in expected_text.lines().enumerate() {
1302                let line_len = snapshot.line_len(output_row as u32);
1303                assert_eq!(line_len, line.len() as u32);
1304            }
1305
1306            let longest_row = snapshot.longest_row();
1307            let longest_char_column = expected_text
1308                .split('\n')
1309                .nth(longest_row as usize)
1310                .unwrap()
1311                .chars()
1312                .count();
1313            let mut fold_point = FoldPoint::new(0, 0);
1314            let mut fold_offset = FoldOffset(0);
1315            let mut char_column = 0;
1316            for c in expected_text.chars() {
1317                let buffer_point = fold_point.to_buffer_point(&snapshot);
1318                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1319                assert_eq!(
1320                    buffer_point.to_fold_point(&snapshot, Right),
1321                    fold_point,
1322                    "{:?} -> fold point",
1323                    buffer_point,
1324                );
1325                assert_eq!(
1326                    fold_point.to_buffer_offset(&snapshot),
1327                    buffer_offset,
1328                    "fold_point.to_buffer_offset({:?})",
1329                    fold_point,
1330                );
1331                assert_eq!(
1332                    fold_point.to_offset(&snapshot),
1333                    fold_offset,
1334                    "fold_point.to_offset({:?})",
1335                    fold_point,
1336                );
1337
1338                if c == '\n' {
1339                    *fold_point.row_mut() += 1;
1340                    *fold_point.column_mut() = 0;
1341                    char_column = 0;
1342                } else {
1343                    *fold_point.column_mut() += c.len_utf8() as u32;
1344                    char_column += 1;
1345                }
1346                fold_offset.0 += c.len_utf8();
1347                if char_column > longest_char_column {
1348                    panic!(
1349                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1350                        longest_row,
1351                        longest_char_column,
1352                        fold_point.row(),
1353                        char_column
1354                    );
1355                }
1356            }
1357
1358            for _ in 0..5 {
1359                let mut start = snapshot
1360                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1361                let mut end = snapshot
1362                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1363                if start > end {
1364                    mem::swap(&mut start, &mut end);
1365                }
1366
1367                let text = &expected_text[start.0..end.0];
1368                log::info!("slicing {:?}..{:?} (text: {:?})", start, end, text);
1369                assert_eq!(
1370                    snapshot
1371                        .chunks(start..end, None)
1372                        .map(|c| c.text)
1373                        .collect::<String>(),
1374                    text,
1375                );
1376            }
1377
1378            for (idx, buffer_row) in expected_buffer_rows.iter().enumerate() {
1379                let fold_row = Point::new(*buffer_row, 0)
1380                    .to_fold_point(&snapshot, Right)
1381                    .row();
1382                assert_eq!(
1383                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1384                    expected_buffer_rows[idx..],
1385                );
1386            }
1387
1388            for fold_range in map.merged_fold_ranges() {
1389                let fold_point = fold_range
1390                    .start
1391                    .to_point(&buffer_snapshot)
1392                    .to_fold_point(&snapshot, Right);
1393                assert!(snapshot.is_line_folded(fold_point.row()));
1394            }
1395
1396            for _ in 0..5 {
1397                let end =
1398                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1399                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1400                let expected_folds = map
1401                    .folds
1402                    .items(&buffer_snapshot)
1403                    .into_iter()
1404                    .filter(|fold| {
1405                        let start = buffer_snapshot.anchor_before(start);
1406                        let end = buffer_snapshot.anchor_after(end);
1407                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1408                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1409                                == Ordering::Greater
1410                    })
1411                    .map(|fold| fold.0)
1412                    .collect::<Vec<_>>();
1413
1414                assert_eq!(
1415                    snapshot
1416                        .folds_in_range(start..end)
1417                        .cloned()
1418                        .collect::<Vec<_>>(),
1419                    expected_folds
1420                );
1421            }
1422
1423            let text = snapshot.text();
1424            for _ in 0..5 {
1425                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1426                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1427                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1428                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1429                let mut start =
1430                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1431                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1432                if start > end {
1433                    mem::swap(&mut start, &mut end);
1434                }
1435
1436                let lines = start..end;
1437                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1438                assert_eq!(
1439                    snapshot.text_summary_for_range(lines),
1440                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1441                )
1442            }
1443
1444            let mut text = initial_snapshot.text();
1445            for (snapshot, edits) in snapshot_edits.drain(..) {
1446                let new_text = snapshot.text();
1447                for edit in edits {
1448                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1449                    let new_bytes = edit.new.start.0..edit.new.end.0;
1450                    text.replace_range(old_bytes, &new_text[new_bytes]);
1451                }
1452
1453                assert_eq!(text, new_text);
1454                initial_snapshot = snapshot;
1455            }
1456        }
1457    }
1458
1459    #[gpui::test]
1460    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1461        let text = sample_text(6, 6, 'a') + "\n";
1462        let buffer = MultiBuffer::build_simple(&text, cx);
1463
1464        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1465        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1466
1467        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1468        writer.fold(vec![
1469            Point::new(0, 2)..Point::new(2, 2),
1470            Point::new(3, 1)..Point::new(4, 1),
1471        ]);
1472
1473        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1474        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1475        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), [0, 3, 5, 6]);
1476        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [6]);
1477    }
1478
1479    impl FoldMap {
1480        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1481            let buffer = self.buffer.lock().clone();
1482            let mut folds = self.folds.items(&buffer);
1483            // Ensure sorting doesn't change how folds get merged and displayed.
1484            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1485            let mut fold_ranges = folds
1486                .iter()
1487                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1488                .peekable();
1489
1490            let mut merged_ranges = Vec::new();
1491            while let Some(mut fold_range) = fold_ranges.next() {
1492                while let Some(next_range) = fold_ranges.peek() {
1493                    if fold_range.end >= next_range.start {
1494                        if next_range.end > fold_range.end {
1495                            fold_range.end = next_range.end;
1496                        }
1497                        fold_ranges.next();
1498                    } else {
1499                        break;
1500                    }
1501                }
1502                if fold_range.end > fold_range.start {
1503                    merged_ranges.push(fold_range);
1504                }
1505            }
1506            merged_ranges
1507        }
1508
1509        pub fn randomly_mutate(
1510            &mut self,
1511            rng: &mut impl Rng,
1512        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1513            let mut snapshot_edits = Vec::new();
1514            match rng.gen_range(0..=100) {
1515                0..=39 if !self.folds.is_empty() => {
1516                    let buffer = self.buffer.lock().clone();
1517                    let mut to_unfold = Vec::new();
1518                    for _ in 0..rng.gen_range(1..=3) {
1519                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1520                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1521                        to_unfold.push(start..end);
1522                    }
1523                    log::info!("unfolding {:?}", to_unfold);
1524                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1525                    snapshot_edits.push((snapshot, edits));
1526                    let (snapshot, edits) = writer.fold(to_unfold);
1527                    snapshot_edits.push((snapshot, edits));
1528                }
1529                _ => {
1530                    let buffer = self.buffer.lock().clone();
1531                    let mut to_fold = Vec::new();
1532                    for _ in 0..rng.gen_range(1..=2) {
1533                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1534                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1535                        to_fold.push(start..end);
1536                    }
1537                    log::info!("folding {:?}", to_fold);
1538                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1539                    snapshot_edits.push((snapshot, edits));
1540                    let (snapshot, edits) = writer.fold(to_fold);
1541                    snapshot_edits.push((snapshot, edits));
1542                }
1543            }
1544            snapshot_edits
1545        }
1546    }
1547}