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