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};
  14use theme::SyntaxTheme;
  15
  16pub trait ToFoldPoint {
  17    fn to_fold_point(&self, snapshot: &FoldSnapshot, bias: Bias) -> FoldPoint;
  18}
  19
  20#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  21pub struct FoldPoint(pub super::Point);
  22
  23impl FoldPoint {
  24    pub fn new(row: u32, column: u32) -> Self {
  25        Self(super::Point::new(row, column))
  26    }
  27
  28    pub fn row(self) -> u32 {
  29        self.0.row
  30    }
  31
  32    pub fn column(self) -> u32 {
  33        self.0.column
  34    }
  35
  36    pub fn row_mut(&mut self) -> &mut u32 {
  37        &mut self.0.row
  38    }
  39
  40    pub fn column_mut(&mut self) -> &mut u32 {
  41        &mut self.0.column
  42    }
  43
  44    pub fn to_buffer_point(&self, snapshot: &FoldSnapshot) -> Point {
  45        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  46        cursor.seek(self, Bias::Right, &());
  47        let overshoot = self.0 - cursor.start().0 .0;
  48        cursor.start().1 + overshoot
  49    }
  50
  51    pub fn to_buffer_offset(&self, snapshot: &FoldSnapshot) -> usize {
  52        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  53        cursor.seek(self, Bias::Right, &());
  54        let overshoot = self.0 - cursor.start().0 .0;
  55        snapshot
  56            .buffer_snapshot
  57            .point_to_offset(cursor.start().1 + overshoot)
  58    }
  59
  60    pub fn to_offset(&self, snapshot: &FoldSnapshot) -> FoldOffset {
  61        let mut cursor = snapshot
  62            .transforms
  63            .cursor::<(FoldPoint, TransformSummary)>();
  64        cursor.seek(self, Bias::Right, &());
  65        let overshoot = self.0 - cursor.start().1.output.lines;
  66        let mut offset = cursor.start().1.output.bytes;
  67        if !overshoot.is_zero() {
  68            let transform = cursor.item().expect("display point out of range");
  69            assert!(transform.output_text.is_none());
  70            let end_buffer_offset = snapshot
  71                .buffer_snapshot
  72                .point_to_offset(cursor.start().1.input.lines + overshoot);
  73            offset += end_buffer_offset - cursor.start().1.input.bytes;
  74        }
  75        FoldOffset(offset)
  76    }
  77}
  78
  79impl ToFoldPoint for Point {
  80    fn to_fold_point(&self, snapshot: &FoldSnapshot, bias: Bias) -> FoldPoint {
  81        let mut cursor = snapshot.transforms.cursor::<(Point, FoldPoint)>();
  82        cursor.seek(self, Bias::Right, &());
  83        if cursor.item().map_or(false, |t| t.is_fold()) {
  84            if bias == Bias::Left || *self == cursor.start().0 {
  85                cursor.start().1
  86            } else {
  87                cursor.end(&()).1
  88            }
  89        } else {
  90            let overshoot = *self - cursor.start().0;
  91            FoldPoint(cmp::min(
  92                cursor.start().1 .0 + overshoot,
  93                cursor.end(&()).1 .0,
  94            ))
  95        }
  96    }
  97}
  98
  99pub struct FoldMapWriter<'a>(&'a mut FoldMap);
 100
 101impl<'a> FoldMapWriter<'a> {
 102    pub fn fold<T: ToOffset>(
 103        &mut self,
 104        ranges: impl IntoIterator<Item = Range<T>>,
 105    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 106        let mut edits = Vec::new();
 107        let mut folds = Vec::new();
 108        let buffer = self.0.buffer.lock().clone();
 109        for range in ranges.into_iter() {
 110            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
 111            if range.start != range.end {
 112                let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 113                folds.push(fold);
 114                edits.push(text::Edit {
 115                    old: range.clone(),
 116                    new: range,
 117                });
 118            }
 119        }
 120
 121        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 122
 123        self.0.folds = {
 124            let mut new_tree = SumTree::new();
 125            let mut cursor = self.0.folds.cursor::<Fold>();
 126            for fold in folds {
 127                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 128                new_tree.push(fold, &buffer);
 129            }
 130            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 131            new_tree
 132        };
 133
 134        consolidate_buffer_edits(&mut edits);
 135        let edits = self.0.sync(buffer.clone(), edits);
 136        let snapshot = FoldSnapshot {
 137            transforms: self.0.transforms.lock().clone(),
 138            folds: self.0.folds.clone(),
 139            buffer_snapshot: buffer,
 140            version: self.0.version.load(SeqCst),
 141        };
 142        (snapshot, edits)
 143    }
 144
 145    pub fn unfold<T: ToOffset>(
 146        &mut self,
 147        ranges: impl IntoIterator<Item = Range<T>>,
 148    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 149        let mut edits = Vec::new();
 150        let mut fold_ixs_to_delete = Vec::new();
 151        let buffer = self.0.buffer.lock().clone();
 152        for range in ranges.into_iter() {
 153            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 154            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 155            while let Some(fold) = folds_cursor.item() {
 156                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 157                if offset_range.end > offset_range.start {
 158                    edits.push(text::Edit {
 159                        old: offset_range.clone(),
 160                        new: offset_range,
 161                    });
 162                }
 163                fold_ixs_to_delete.push(*folds_cursor.start());
 164                folds_cursor.next(&buffer);
 165            }
 166        }
 167
 168        fold_ixs_to_delete.sort_unstable();
 169        fold_ixs_to_delete.dedup();
 170
 171        self.0.folds = {
 172            let mut cursor = self.0.folds.cursor::<usize>();
 173            let mut folds = SumTree::new();
 174            for fold_ix in fold_ixs_to_delete {
 175                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 176                cursor.next(&buffer);
 177            }
 178            folds.push_tree(cursor.suffix(&buffer), &buffer);
 179            folds
 180        };
 181
 182        consolidate_buffer_edits(&mut edits);
 183        let edits = self.0.sync(buffer.clone(), edits);
 184        let snapshot = FoldSnapshot {
 185            transforms: self.0.transforms.lock().clone(),
 186            folds: self.0.folds.clone(),
 187            buffer_snapshot: buffer,
 188            version: self.0.version.load(SeqCst),
 189        };
 190        (snapshot, edits)
 191    }
 192}
 193
 194pub struct FoldMap {
 195    buffer: Mutex<MultiBufferSnapshot>,
 196    transforms: Mutex<SumTree<Transform>>,
 197    folds: SumTree<Fold>,
 198    version: AtomicUsize,
 199}
 200
 201impl FoldMap {
 202    pub fn new(buffer: MultiBufferSnapshot) -> (Self, FoldSnapshot) {
 203        let this = Self {
 204            buffer: Mutex::new(buffer.clone()),
 205            folds: Default::default(),
 206            transforms: Mutex::new(SumTree::from_item(
 207                Transform {
 208                    summary: TransformSummary {
 209                        input: buffer.text_summary(),
 210                        output: buffer.text_summary(),
 211                    },
 212                    output_text: None,
 213                },
 214                &(),
 215            )),
 216            version: Default::default(),
 217        };
 218
 219        let snapshot = FoldSnapshot {
 220            transforms: this.transforms.lock().clone(),
 221            folds: this.folds.clone(),
 222            buffer_snapshot: this.buffer.lock().clone(),
 223            version: this.version.load(SeqCst),
 224        };
 225        (this, snapshot)
 226    }
 227
 228    pub fn read(
 229        &self,
 230        buffer: MultiBufferSnapshot,
 231        edits: Vec<Edit<usize>>,
 232    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 233        let edits = self.sync(buffer, edits);
 234        self.check_invariants();
 235        let snapshot = FoldSnapshot {
 236            transforms: self.transforms.lock().clone(),
 237            folds: self.folds.clone(),
 238            buffer_snapshot: self.buffer.lock().clone(),
 239            version: self.version.load(SeqCst),
 240        };
 241        (snapshot, edits)
 242    }
 243
 244    pub fn write(
 245        &mut self,
 246        buffer: MultiBufferSnapshot,
 247        edits: Vec<Edit<usize>>,
 248    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 249        let (snapshot, edits) = self.read(buffer, edits);
 250        (FoldMapWriter(self), snapshot, edits)
 251    }
 252
 253    fn check_invariants(&self) {
 254        if cfg!(test) {
 255            assert_eq!(
 256                self.transforms.lock().summary().input.bytes,
 257                self.buffer.lock().len(),
 258                "transform tree does not match buffer's length"
 259            );
 260        }
 261    }
 262
 263    fn sync(
 264        &self,
 265        new_buffer: MultiBufferSnapshot,
 266        buffer_edits: Vec<text::Edit<usize>>,
 267    ) -> Vec<FoldEdit> {
 268        if buffer_edits.is_empty() {
 269            let mut buffer = self.buffer.lock();
 270            if buffer.parse_count() != new_buffer.parse_count()
 271                || buffer.diagnostics_update_count() != new_buffer.diagnostics_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(), None)
 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(), None)
 634            .flat_map(|chunk| chunk.text.chars())
 635    }
 636
 637    pub fn chunks<'a>(
 638        &'a self,
 639        range: Range<FoldOffset>,
 640        theme: Option<&'a SyntaxTheme>,
 641    ) -> 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.buffer_snapshot.chunks(buffer_start..buffer_end, theme),
 655            buffer_chunk: None,
 656            buffer_offset: buffer_start,
 657            output_offset: range.start.0,
 658            max_output_offset: range.end.0,
 659        }
 660    }
 661
 662    #[cfg(test)]
 663    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 664        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 665        cursor.seek(&offset, Bias::Right, &());
 666        if let Some(transform) = cursor.item() {
 667            let transform_start = cursor.start().0 .0;
 668            if transform.output_text.is_some() {
 669                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 670                    FoldOffset(transform_start)
 671                } else {
 672                    FoldOffset(cursor.end(&()).0 .0)
 673                }
 674            } else {
 675                let overshoot = offset.0 - transform_start;
 676                let buffer_offset = cursor.start().1 + overshoot;
 677                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 678                FoldOffset(
 679                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 680                        as usize,
 681                )
 682            }
 683        } else {
 684            FoldOffset(self.transforms.summary().output.bytes)
 685        }
 686    }
 687
 688    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 689        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 690        cursor.seek(&point, Bias::Right, &());
 691        if let Some(transform) = cursor.item() {
 692            let transform_start = cursor.start().0 .0;
 693            if transform.output_text.is_some() {
 694                if point.0 == transform_start || matches!(bias, Bias::Left) {
 695                    FoldPoint(transform_start)
 696                } else {
 697                    FoldPoint(cursor.end(&()).0 .0)
 698                }
 699            } else {
 700                let overshoot = point.0 - transform_start;
 701                let buffer_position = cursor.start().1 + overshoot;
 702                let clipped_buffer_position =
 703                    self.buffer_snapshot.clip_point(buffer_position, bias);
 704                FoldPoint(cursor.start().0 .0 + (clipped_buffer_position - cursor.start().1))
 705            }
 706        } else {
 707            FoldPoint(self.transforms.summary().output.lines)
 708        }
 709    }
 710}
 711
 712fn intersecting_folds<'a, T>(
 713    buffer: &'a MultiBufferSnapshot,
 714    folds: &'a SumTree<Fold>,
 715    range: Range<T>,
 716    inclusive: bool,
 717) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 718where
 719    T: ToOffset,
 720{
 721    let start = buffer.anchor_before(range.start.to_offset(buffer));
 722    let end = buffer.anchor_after(range.end.to_offset(buffer));
 723    folds.filter::<_, usize>(
 724        move |summary| {
 725            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 726            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 727
 728            if inclusive {
 729                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 730            } else {
 731                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 732            }
 733        },
 734        buffer,
 735    )
 736}
 737
 738fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 739    edits.sort_unstable_by(|a, b| {
 740        a.old
 741            .start
 742            .cmp(&b.old.start)
 743            .then_with(|| b.old.end.cmp(&a.old.end))
 744    });
 745
 746    let mut i = 1;
 747    while i < edits.len() {
 748        let edit = edits[i].clone();
 749        let prev_edit = &mut edits[i - 1];
 750        if prev_edit.old.end >= edit.old.start {
 751            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 752            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 753            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 754            edits.remove(i);
 755            continue;
 756        }
 757        i += 1;
 758    }
 759}
 760
 761fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 762    edits.sort_unstable_by(|a, b| {
 763        a.old
 764            .start
 765            .cmp(&b.old.start)
 766            .then_with(|| b.old.end.cmp(&a.old.end))
 767    });
 768
 769    let mut i = 1;
 770    while i < edits.len() {
 771        let edit = edits[i].clone();
 772        let prev_edit = &mut edits[i - 1];
 773        if prev_edit.old.end >= edit.old.start {
 774            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 775            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 776            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 777            edits.remove(i);
 778            continue;
 779        }
 780        i += 1;
 781    }
 782}
 783
 784#[derive(Clone, Debug, Default, Eq, PartialEq)]
 785struct Transform {
 786    summary: TransformSummary,
 787    output_text: Option<&'static str>,
 788}
 789
 790impl Transform {
 791    fn is_fold(&self) -> bool {
 792        self.output_text.is_some()
 793    }
 794}
 795
 796#[derive(Clone, Debug, Default, Eq, PartialEq)]
 797struct TransformSummary {
 798    output: TextSummary,
 799    input: TextSummary,
 800}
 801
 802impl sum_tree::Item for Transform {
 803    type Summary = TransformSummary;
 804
 805    fn summary(&self) -> Self::Summary {
 806        self.summary.clone()
 807    }
 808}
 809
 810impl sum_tree::Summary for TransformSummary {
 811    type Context = ();
 812
 813    fn add_summary(&mut self, other: &Self, _: &()) {
 814        self.input += &other.input;
 815        self.output += &other.output;
 816    }
 817}
 818
 819#[derive(Clone, Debug)]
 820struct Fold(Range<Anchor>);
 821
 822impl Default for Fold {
 823    fn default() -> Self {
 824        Self(Anchor::min()..Anchor::max())
 825    }
 826}
 827
 828impl sum_tree::Item for Fold {
 829    type Summary = FoldSummary;
 830
 831    fn summary(&self) -> Self::Summary {
 832        FoldSummary {
 833            start: self.0.start.clone(),
 834            end: self.0.end.clone(),
 835            min_start: self.0.start.clone(),
 836            max_end: self.0.end.clone(),
 837            count: 1,
 838        }
 839    }
 840}
 841
 842#[derive(Clone, Debug)]
 843struct FoldSummary {
 844    start: Anchor,
 845    end: Anchor,
 846    min_start: Anchor,
 847    max_end: Anchor,
 848    count: usize,
 849}
 850
 851impl Default for FoldSummary {
 852    fn default() -> Self {
 853        Self {
 854            start: Anchor::min(),
 855            end: Anchor::max(),
 856            min_start: Anchor::max(),
 857            max_end: Anchor::min(),
 858            count: 0,
 859        }
 860    }
 861}
 862
 863impl sum_tree::Summary for FoldSummary {
 864    type Context = MultiBufferSnapshot;
 865
 866    fn add_summary(&mut self, other: &Self, buffer: &MultiBufferSnapshot) {
 867        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 868            self.min_start = other.min_start.clone();
 869        }
 870        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 871            self.max_end = other.max_end.clone();
 872        }
 873
 874        #[cfg(debug_assertions)]
 875        {
 876            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 877            assert!(start_comparison <= Ordering::Equal);
 878            if start_comparison == Ordering::Equal {
 879                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 880            }
 881        }
 882
 883        self.start = other.start.clone();
 884        self.end = other.end.clone();
 885        self.count += other.count;
 886    }
 887}
 888
 889impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 890    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 891        self.0.start = summary.start.clone();
 892        self.0.end = summary.end.clone();
 893    }
 894}
 895
 896impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 897    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
 898        self.0.cmp(&other.0, buffer).unwrap()
 899    }
 900}
 901
 902impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 903    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 904        *self += summary.count;
 905    }
 906}
 907
 908pub struct FoldBufferRows<'a> {
 909    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 910    input_buffer_rows: MultiBufferRows<'a>,
 911    fold_point: FoldPoint,
 912}
 913
 914impl<'a> Iterator for FoldBufferRows<'a> {
 915    type Item = Option<u32>;
 916
 917    fn next(&mut self) -> Option<Self::Item> {
 918        let mut traversed_fold = false;
 919        while self.fold_point > self.cursor.end(&()).0 {
 920            self.cursor.next(&());
 921            traversed_fold = true;
 922            if self.cursor.item().is_none() {
 923                break;
 924            }
 925        }
 926
 927        if self.cursor.item().is_some() {
 928            if traversed_fold {
 929                self.input_buffer_rows.seek(self.cursor.start().1.row);
 930                self.input_buffer_rows.next();
 931            }
 932            *self.fold_point.row_mut() += 1;
 933            self.input_buffer_rows.next()
 934        } else {
 935            None
 936        }
 937    }
 938}
 939
 940pub struct FoldChunks<'a> {
 941    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 942    buffer_chunks: MultiBufferChunks<'a>,
 943    buffer_chunk: Option<(usize, Chunk<'a>)>,
 944    buffer_offset: usize,
 945    output_offset: usize,
 946    max_output_offset: usize,
 947}
 948
 949impl<'a> Iterator for FoldChunks<'a> {
 950    type Item = Chunk<'a>;
 951
 952    fn next(&mut self) -> Option<Self::Item> {
 953        if self.output_offset >= self.max_output_offset {
 954            return None;
 955        }
 956
 957        let transform = if let Some(item) = self.transform_cursor.item() {
 958            item
 959        } else {
 960            return None;
 961        };
 962
 963        // If we're in a fold, then return the fold's display text and
 964        // advance the transform and buffer cursors to the end of the fold.
 965        if let Some(output_text) = transform.output_text {
 966            self.buffer_chunk.take();
 967            self.buffer_offset += transform.summary.input.bytes;
 968            self.buffer_chunks.seek(self.buffer_offset);
 969
 970            while self.buffer_offset >= self.transform_cursor.end(&()).1
 971                && self.transform_cursor.item().is_some()
 972            {
 973                self.transform_cursor.next(&());
 974            }
 975
 976            self.output_offset += output_text.len();
 977            return Some(Chunk {
 978                text: output_text,
 979                highlight_style: None,
 980                diagnostic: None,
 981            });
 982        }
 983
 984        // Retrieve a chunk from the current location in the buffer.
 985        if self.buffer_chunk.is_none() {
 986            let chunk_offset = self.buffer_chunks.offset();
 987            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
 988        }
 989
 990        // Otherwise, take a chunk from the buffer's text.
 991        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
 992            let offset_in_chunk = self.buffer_offset - chunk_offset;
 993            chunk.text = &chunk.text[offset_in_chunk..];
 994
 995            // Truncate the chunk so that it ends at the next fold.
 996            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 997            if chunk.text.len() >= region_end {
 998                chunk.text = &chunk.text[0..region_end];
 999                self.transform_cursor.next(&());
1000            } else {
1001                self.buffer_chunk.take();
1002            }
1003
1004            self.buffer_offset += chunk.text.len();
1005            self.output_offset += chunk.text.len();
1006            return Some(chunk);
1007        }
1008
1009        None
1010    }
1011}
1012
1013impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1014    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1015        self.0 += &summary.output.lines;
1016    }
1017}
1018
1019#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1020pub struct FoldOffset(pub usize);
1021
1022impl FoldOffset {
1023    pub fn to_point(&self, snapshot: &FoldSnapshot) -> FoldPoint {
1024        let mut cursor = snapshot
1025            .transforms
1026            .cursor::<(FoldOffset, TransformSummary)>();
1027        cursor.seek(self, Bias::Right, &());
1028        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1029            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1030        } else {
1031            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1032            let buffer_point = snapshot.buffer_snapshot.offset_to_point(buffer_offset);
1033            buffer_point - cursor.start().1.input.lines
1034        };
1035        FoldPoint(cursor.start().1.output.lines + overshoot)
1036    }
1037}
1038
1039impl Sub for FoldOffset {
1040    type Output = Self;
1041
1042    fn sub(self, rhs: Self) -> Self::Output {
1043        Self(self.0 - rhs.0)
1044    }
1045}
1046
1047impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1048    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1049        self.0 += &summary.output.bytes;
1050    }
1051}
1052
1053impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1054    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1055        *self += &summary.input.lines;
1056    }
1057}
1058
1059impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1060    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1061        *self += &summary.input.bytes;
1062    }
1063}
1064
1065pub type FoldEdit = Edit<FoldOffset>;
1066
1067#[cfg(test)]
1068mod tests {
1069    use super::*;
1070    use crate::{MultiBuffer, ToPoint};
1071    use rand::prelude::*;
1072    use std::{env, mem};
1073    use text::RandomCharIter;
1074    use util::test::sample_text;
1075    use Bias::{Left, Right};
1076
1077    #[gpui::test]
1078    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1079        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1080        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1081        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1082        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1083
1084        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1085        let (snapshot2, edits) = writer.fold(vec![
1086            Point::new(0, 2)..Point::new(2, 2),
1087            Point::new(2, 4)..Point::new(4, 1),
1088        ]);
1089        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1090        assert_eq!(
1091            edits,
1092            &[
1093                FoldEdit {
1094                    old: FoldOffset(2)..FoldOffset(16),
1095                    new: FoldOffset(2)..FoldOffset(5),
1096                },
1097                FoldEdit {
1098                    old: FoldOffset(18)..FoldOffset(29),
1099                    new: FoldOffset(7)..FoldOffset(10)
1100                },
1101            ]
1102        );
1103
1104        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1105            buffer.edit(
1106                vec![
1107                    Point::new(0, 0)..Point::new(0, 1),
1108                    Point::new(2, 3)..Point::new(2, 3),
1109                ],
1110                "123",
1111                cx,
1112            );
1113            buffer.snapshot(cx)
1114        });
1115        let (snapshot3, edits) =
1116            map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1117        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1118        assert_eq!(
1119            edits,
1120            &[
1121                FoldEdit {
1122                    old: FoldOffset(0)..FoldOffset(1),
1123                    new: FoldOffset(0)..FoldOffset(3),
1124                },
1125                FoldEdit {
1126                    old: FoldOffset(6)..FoldOffset(6),
1127                    new: FoldOffset(8)..FoldOffset(11),
1128                },
1129            ]
1130        );
1131
1132        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1133            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1134            buffer.snapshot(cx)
1135        });
1136        let (snapshot4, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1137        assert_eq!(snapshot4.text(), "123a…c123456eee");
1138
1139        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1140        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1141        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1142        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1143    }
1144
1145    #[gpui::test]
1146    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1147        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1148        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1149        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1150
1151        {
1152            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1153
1154            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1155            writer.fold(vec![5..8]);
1156            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1157            assert_eq!(snapshot.text(), "abcde…ijkl");
1158
1159            // Create an fold adjacent to the start of the first fold.
1160            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1161            writer.fold(vec![0..1, 2..5]);
1162            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1163            assert_eq!(snapshot.text(), "…b…ijkl");
1164
1165            // Create an fold adjacent to the end of the first fold.
1166            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1167            writer.fold(vec![11..11, 8..10]);
1168            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1169            assert_eq!(snapshot.text(), "…b…kl");
1170        }
1171
1172        {
1173            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1174
1175            // Create two adjacent folds.
1176            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1177            writer.fold(vec![0..2, 2..5]);
1178            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1179            assert_eq!(snapshot.text(), "…fghijkl");
1180
1181            // Edit within one of the folds.
1182            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1183                buffer.edit(vec![0..1], "12345", cx);
1184                buffer.snapshot(cx)
1185            });
1186            let (snapshot, _) =
1187                map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1188            assert_eq!(snapshot.text(), "12345…fghijkl");
1189        }
1190    }
1191
1192    #[gpui::test]
1193    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1194        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1195        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1196        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1197        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1198        writer.fold(vec![
1199            Point::new(0, 2)..Point::new(2, 2),
1200            Point::new(0, 4)..Point::new(1, 0),
1201            Point::new(1, 2)..Point::new(3, 2),
1202            Point::new(3, 1)..Point::new(4, 1),
1203        ]);
1204        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1205        assert_eq!(snapshot.text(), "aa…eeeee");
1206    }
1207
1208    #[gpui::test]
1209    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1210        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1211        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1212        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1213        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1214
1215        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1216        writer.fold(vec![
1217            Point::new(0, 2)..Point::new(2, 2),
1218            Point::new(3, 1)..Point::new(4, 1),
1219        ]);
1220        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1221        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1222
1223        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1224            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1225            buffer.snapshot(cx)
1226        });
1227        let (snapshot, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1228        assert_eq!(snapshot.text(), "aa…eeeee");
1229    }
1230
1231    #[gpui::test]
1232    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1233        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1234        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1235        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1236
1237        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1238        writer.fold(vec![
1239            Point::new(0, 2)..Point::new(2, 2),
1240            Point::new(0, 4)..Point::new(1, 0),
1241            Point::new(1, 2)..Point::new(3, 2),
1242            Point::new(3, 1)..Point::new(4, 1),
1243        ]);
1244        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1245        let fold_ranges = snapshot
1246            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1247            .map(|fold| fold.start.to_point(&buffer_snapshot)..fold.end.to_point(&buffer_snapshot))
1248            .collect::<Vec<_>>();
1249        assert_eq!(
1250            fold_ranges,
1251            vec![
1252                Point::new(0, 2)..Point::new(2, 2),
1253                Point::new(1, 2)..Point::new(3, 2)
1254            ]
1255        );
1256    }
1257
1258    #[gpui::test(iterations = 100)]
1259    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1260        let operations = env::var("OPERATIONS")
1261            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1262            .unwrap_or(10);
1263
1264        let len = rng.gen_range(0..10);
1265        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1266        let buffer = if rng.gen() {
1267            MultiBuffer::build_simple(&text, cx)
1268        } else {
1269            MultiBuffer::build_random(&mut rng, cx)
1270        };
1271        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1272        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1273
1274        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1275        let mut snapshot_edits = Vec::new();
1276
1277        for _ in 0..operations {
1278            log::info!("text: {:?}", buffer_snapshot.text());
1279            let mut buffer_edits = Vec::new();
1280            match rng.gen_range(0..=100) {
1281                0..=59 => {
1282                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1283                }
1284                _ => buffer.update(cx, |buffer, cx| {
1285                    let subscription = buffer.subscribe();
1286                    let edit_count = rng.gen_range(1..=5);
1287                    buffer.randomly_edit(&mut rng, edit_count, cx);
1288                    buffer_snapshot = buffer.snapshot(cx);
1289                    let edits = subscription.consume().into_inner();
1290                    log::info!("editing {:?}", edits);
1291                    buffer_edits.extend(edits);
1292                }),
1293            };
1294
1295            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1296            snapshot_edits.push((snapshot.clone(), edits));
1297
1298            let mut expected_text: String = buffer_snapshot.text().to_string();
1299            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1300                expected_text.replace_range(fold_range.start..fold_range.end, "…");
1301            }
1302
1303            assert_eq!(snapshot.text(), expected_text);
1304            log::info!(
1305                "fold text {:?} ({} lines)",
1306                expected_text,
1307                expected_text.matches('\n').count() + 1
1308            );
1309
1310            let mut prev_row = 0;
1311            let mut expected_buffer_rows = Vec::new();
1312            for fold_range in map.merged_fold_ranges().into_iter() {
1313                let fold_start = buffer_snapshot.offset_to_point(fold_range.start).row;
1314                let fold_end = buffer_snapshot.offset_to_point(fold_range.end).row;
1315                expected_buffer_rows.extend(
1316                    buffer_snapshot
1317                        .buffer_rows(prev_row)
1318                        .take((1 + fold_start - prev_row) as usize),
1319                );
1320                prev_row = 1 + fold_end;
1321            }
1322            expected_buffer_rows.extend(buffer_snapshot.buffer_rows(prev_row));
1323
1324            assert_eq!(
1325                expected_buffer_rows.len(),
1326                expected_text.matches('\n').count() + 1,
1327                "wrong expected buffer rows {:?}. text: {:?}",
1328                expected_buffer_rows,
1329                expected_text
1330            );
1331
1332            for (output_row, line) in expected_text.lines().enumerate() {
1333                let line_len = snapshot.line_len(output_row as u32);
1334                assert_eq!(line_len, line.len() as u32);
1335            }
1336
1337            let longest_row = snapshot.longest_row();
1338            let longest_char_column = expected_text
1339                .split('\n')
1340                .nth(longest_row as usize)
1341                .unwrap()
1342                .chars()
1343                .count();
1344            let mut fold_point = FoldPoint::new(0, 0);
1345            let mut fold_offset = FoldOffset(0);
1346            let mut char_column = 0;
1347            for c in expected_text.chars() {
1348                let buffer_point = fold_point.to_buffer_point(&snapshot);
1349                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1350                assert_eq!(
1351                    buffer_point.to_fold_point(&snapshot, Right),
1352                    fold_point,
1353                    "{:?} -> fold point",
1354                    buffer_point,
1355                );
1356                assert_eq!(
1357                    fold_point.to_buffer_offset(&snapshot),
1358                    buffer_offset,
1359                    "fold_point.to_buffer_offset({:?})",
1360                    fold_point,
1361                );
1362                assert_eq!(
1363                    fold_point.to_offset(&snapshot),
1364                    fold_offset,
1365                    "fold_point.to_offset({:?})",
1366                    fold_point,
1367                );
1368
1369                if c == '\n' {
1370                    *fold_point.row_mut() += 1;
1371                    *fold_point.column_mut() = 0;
1372                    char_column = 0;
1373                } else {
1374                    *fold_point.column_mut() += c.len_utf8() as u32;
1375                    char_column += 1;
1376                }
1377                fold_offset.0 += c.len_utf8();
1378                if char_column > longest_char_column {
1379                    panic!(
1380                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1381                        longest_row,
1382                        longest_char_column,
1383                        fold_point.row(),
1384                        char_column
1385                    );
1386                }
1387            }
1388
1389            for _ in 0..5 {
1390                let mut start = snapshot
1391                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1392                let mut end = snapshot
1393                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1394                if start > end {
1395                    mem::swap(&mut start, &mut end);
1396                }
1397
1398                let text = &expected_text[start.0..end.0];
1399                assert_eq!(
1400                    snapshot
1401                        .chunks(start..end, None)
1402                        .map(|c| c.text)
1403                        .collect::<String>(),
1404                    text,
1405                );
1406            }
1407
1408            let mut fold_row = 0;
1409            while fold_row < expected_buffer_rows.len() as u32 {
1410                fold_row = snapshot
1411                    .clip_point(FoldPoint::new(fold_row, 0), Bias::Right)
1412                    .row();
1413                eprintln!("fold_row: {} of {}", fold_row, expected_buffer_rows.len());
1414                assert_eq!(
1415                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1416                    expected_buffer_rows[(fold_row as usize)..],
1417                    "wrong buffer rows starting at fold row {}",
1418                    fold_row,
1419                );
1420                fold_row += 1;
1421            }
1422
1423            for fold_range in map.merged_fold_ranges() {
1424                let fold_point = fold_range
1425                    .start
1426                    .to_point(&buffer_snapshot)
1427                    .to_fold_point(&snapshot, Right);
1428                assert!(snapshot.is_line_folded(fold_point.row()));
1429            }
1430
1431            for _ in 0..5 {
1432                let end =
1433                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1434                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1435                let expected_folds = map
1436                    .folds
1437                    .items(&buffer_snapshot)
1438                    .into_iter()
1439                    .filter(|fold| {
1440                        let start = buffer_snapshot.anchor_before(start);
1441                        let end = buffer_snapshot.anchor_after(end);
1442                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1443                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1444                                == Ordering::Greater
1445                    })
1446                    .map(|fold| fold.0)
1447                    .collect::<Vec<_>>();
1448
1449                assert_eq!(
1450                    snapshot
1451                        .folds_in_range(start..end)
1452                        .cloned()
1453                        .collect::<Vec<_>>(),
1454                    expected_folds
1455                );
1456            }
1457
1458            let text = snapshot.text();
1459            for _ in 0..5 {
1460                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1461                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1462                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1463                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1464                let mut start =
1465                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1466                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1467                if start > end {
1468                    mem::swap(&mut start, &mut end);
1469                }
1470
1471                let lines = start..end;
1472                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1473                assert_eq!(
1474                    snapshot.text_summary_for_range(lines),
1475                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1476                )
1477            }
1478
1479            let mut text = initial_snapshot.text();
1480            for (snapshot, edits) in snapshot_edits.drain(..) {
1481                let new_text = snapshot.text();
1482                for edit in edits {
1483                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1484                    let new_bytes = edit.new.start.0..edit.new.end.0;
1485                    text.replace_range(old_bytes, &new_text[new_bytes]);
1486                }
1487
1488                assert_eq!(text, new_text);
1489                initial_snapshot = snapshot;
1490            }
1491        }
1492    }
1493
1494    #[gpui::test]
1495    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1496        let text = sample_text(6, 6, 'a') + "\n";
1497        let buffer = MultiBuffer::build_simple(&text, cx);
1498
1499        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1500        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1501
1502        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1503        writer.fold(vec![
1504            Point::new(0, 2)..Point::new(2, 2),
1505            Point::new(3, 1)..Point::new(4, 1),
1506        ]);
1507
1508        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1509        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1510        assert_eq!(
1511            snapshot.buffer_rows(0).collect::<Vec<_>>(),
1512            [Some(0), Some(3), Some(5), Some(6)]
1513        );
1514        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [Some(6)]);
1515    }
1516
1517    impl FoldMap {
1518        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1519            let buffer = self.buffer.lock().clone();
1520            let mut folds = self.folds.items(&buffer);
1521            // Ensure sorting doesn't change how folds get merged and displayed.
1522            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1523            let mut fold_ranges = folds
1524                .iter()
1525                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1526                .peekable();
1527
1528            let mut merged_ranges = Vec::new();
1529            while let Some(mut fold_range) = fold_ranges.next() {
1530                while let Some(next_range) = fold_ranges.peek() {
1531                    if fold_range.end >= next_range.start {
1532                        if next_range.end > fold_range.end {
1533                            fold_range.end = next_range.end;
1534                        }
1535                        fold_ranges.next();
1536                    } else {
1537                        break;
1538                    }
1539                }
1540                if fold_range.end > fold_range.start {
1541                    merged_ranges.push(fold_range);
1542                }
1543            }
1544            merged_ranges
1545        }
1546
1547        pub fn randomly_mutate(
1548            &mut self,
1549            rng: &mut impl Rng,
1550        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1551            let mut snapshot_edits = Vec::new();
1552            match rng.gen_range(0..=100) {
1553                0..=39 if !self.folds.is_empty() => {
1554                    let buffer = self.buffer.lock().clone();
1555                    let mut to_unfold = Vec::new();
1556                    for _ in 0..rng.gen_range(1..=3) {
1557                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1558                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1559                        to_unfold.push(start..end);
1560                    }
1561                    log::info!("unfolding {:?}", to_unfold);
1562                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1563                    snapshot_edits.push((snapshot, edits));
1564                    let (snapshot, edits) = writer.fold(to_unfold);
1565                    snapshot_edits.push((snapshot, edits));
1566                }
1567                _ => {
1568                    let buffer = self.buffer.lock().clone();
1569                    let mut to_fold = Vec::new();
1570                    for _ in 0..rng.gen_range(1..=2) {
1571                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1572                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1573                        to_fold.push(start..end);
1574                    }
1575                    log::info!("folding {:?}", to_fold);
1576                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1577                    snapshot_edits.push((snapshot, edits));
1578                    let (snapshot, edits) = writer.fold(to_fold);
1579                    snapshot_edits.push((snapshot, edits));
1580                }
1581            }
1582            snapshot_edits
1583        }
1584    }
1585}