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