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