1use super::TextHighlights;
   2use crate::{
   3    multi_buffer::MultiBufferRows, Anchor, AnchorRangeExt, MultiBufferChunks, MultiBufferSnapshot,
   4    ToOffset,
   5};
   6use collections::BTreeMap;
   7use gpui::fonts::HighlightStyle;
   8use language::{Chunk, Edit, Point, PointUtf16, TextSummary};
   9use parking_lot::Mutex;
  10use std::{
  11    any::TypeId,
  12    cmp::{self, Ordering},
  13    iter::{self, Peekable},
  14    ops::{Range, Sub},
  15    sync::atomic::{AtomicUsize, Ordering::SeqCst},
  16    vec,
  17};
  18use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  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<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
  80    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
  81        self.0 += &summary.output.lines;
  82    }
  83}
  84
  85pub struct FoldMapWriter<'a>(&'a mut FoldMap);
  86
  87impl<'a> FoldMapWriter<'a> {
  88    pub fn fold<T: ToOffset>(
  89        &mut self,
  90        ranges: impl IntoIterator<Item = Range<T>>,
  91    ) -> (FoldSnapshot, Vec<FoldEdit>) {
  92        let mut edits = Vec::new();
  93        let mut folds = Vec::new();
  94        let buffer = self.0.buffer.lock().clone();
  95        for range in ranges.into_iter() {
  96            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
  97
  98            // Ignore any empty ranges.
  99            if range.start == range.end {
 100                continue;
 101            }
 102
 103            // For now, ignore any ranges that span an excerpt boundary.
 104            let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 105            if fold.0.start.excerpt_id() != fold.0.end.excerpt_id() {
 106                continue;
 107            }
 108
 109            folds.push(fold);
 110            edits.push(text::Edit {
 111                old: range.clone(),
 112                new: range,
 113            });
 114        }
 115
 116        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 117
 118        self.0.folds = {
 119            let mut new_tree = SumTree::new();
 120            let mut cursor = self.0.folds.cursor::<Fold>();
 121            for fold in folds {
 122                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 123                new_tree.push(fold, &buffer);
 124            }
 125            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 126            new_tree
 127        };
 128
 129        consolidate_buffer_edits(&mut edits);
 130        let edits = self.0.sync(buffer.clone(), edits);
 131        let snapshot = FoldSnapshot {
 132            transforms: self.0.transforms.lock().clone(),
 133            folds: self.0.folds.clone(),
 134            buffer_snapshot: buffer,
 135            version: self.0.version.load(SeqCst),
 136        };
 137        (snapshot, edits)
 138    }
 139
 140    pub fn unfold<T: ToOffset>(
 141        &mut self,
 142        ranges: impl IntoIterator<Item = Range<T>>,
 143    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 144        let mut edits = Vec::new();
 145        let mut fold_ixs_to_delete = Vec::new();
 146        let buffer = self.0.buffer.lock().clone();
 147        for range in ranges.into_iter() {
 148            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 149            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 150            while let Some(fold) = folds_cursor.item() {
 151                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 152                if offset_range.end > offset_range.start {
 153                    edits.push(text::Edit {
 154                        old: offset_range.clone(),
 155                        new: offset_range,
 156                    });
 157                }
 158                fold_ixs_to_delete.push(*folds_cursor.start());
 159                folds_cursor.next(&buffer);
 160            }
 161        }
 162
 163        fold_ixs_to_delete.sort_unstable();
 164        fold_ixs_to_delete.dedup();
 165
 166        self.0.folds = {
 167            let mut cursor = self.0.folds.cursor::<usize>();
 168            let mut folds = SumTree::new();
 169            for fold_ix in fold_ixs_to_delete {
 170                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 171                cursor.next(&buffer);
 172            }
 173            folds.push_tree(cursor.suffix(&buffer), &buffer);
 174            folds
 175        };
 176
 177        consolidate_buffer_edits(&mut edits);
 178        let edits = self.0.sync(buffer.clone(), edits);
 179        let snapshot = FoldSnapshot {
 180            transforms: self.0.transforms.lock().clone(),
 181            folds: self.0.folds.clone(),
 182            buffer_snapshot: buffer,
 183            version: self.0.version.load(SeqCst),
 184        };
 185        (snapshot, edits)
 186    }
 187}
 188
 189pub struct FoldMap {
 190    buffer: Mutex<MultiBufferSnapshot>,
 191    transforms: Mutex<SumTree<Transform>>,
 192    folds: SumTree<Fold>,
 193    version: AtomicUsize,
 194}
 195
 196impl FoldMap {
 197    pub fn new(buffer: MultiBufferSnapshot) -> (Self, FoldSnapshot) {
 198        let this = Self {
 199            buffer: Mutex::new(buffer.clone()),
 200            folds: Default::default(),
 201            transforms: Mutex::new(SumTree::from_item(
 202                Transform {
 203                    summary: TransformSummary {
 204                        input: buffer.text_summary(),
 205                        output: buffer.text_summary(),
 206                    },
 207                    output_text: None,
 208                },
 209                &(),
 210            )),
 211            version: Default::default(),
 212        };
 213
 214        let snapshot = FoldSnapshot {
 215            transforms: this.transforms.lock().clone(),
 216            folds: this.folds.clone(),
 217            buffer_snapshot: this.buffer.lock().clone(),
 218            version: this.version.load(SeqCst),
 219        };
 220        (this, snapshot)
 221    }
 222
 223    pub fn read(
 224        &self,
 225        buffer: MultiBufferSnapshot,
 226        edits: Vec<Edit<usize>>,
 227    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 228        let edits = self.sync(buffer, edits);
 229        self.check_invariants();
 230        let snapshot = FoldSnapshot {
 231            transforms: self.transforms.lock().clone(),
 232            folds: self.folds.clone(),
 233            buffer_snapshot: self.buffer.lock().clone(),
 234            version: self.version.load(SeqCst),
 235        };
 236        (snapshot, edits)
 237    }
 238
 239    pub fn write(
 240        &mut self,
 241        buffer: MultiBufferSnapshot,
 242        edits: Vec<Edit<usize>>,
 243    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 244        let (snapshot, edits) = self.read(buffer, edits);
 245        (FoldMapWriter(self), snapshot, edits)
 246    }
 247
 248    fn check_invariants(&self) {
 249        if cfg!(test) {
 250            assert_eq!(
 251                self.transforms.lock().summary().input.bytes,
 252                self.buffer.lock().len(),
 253                "transform tree does not match buffer's length"
 254            );
 255
 256            let mut folds = self.folds.iter().peekable();
 257            while let Some(fold) = folds.next() {
 258                if let Some(next_fold) = folds.peek() {
 259                    let comparison = fold.0.cmp(&next_fold.0, &self.buffer.lock()).unwrap();
 260                    assert!(comparison.is_le());
 261                }
 262            }
 263        }
 264    }
 265
 266    fn sync(
 267        &self,
 268        new_buffer: MultiBufferSnapshot,
 269        buffer_edits: Vec<text::Edit<usize>>,
 270    ) -> Vec<FoldEdit> {
 271        if buffer_edits.is_empty() {
 272            let mut buffer = self.buffer.lock();
 273            if buffer.parse_count() != new_buffer.parse_count()
 274                || buffer.diagnostics_update_count() != new_buffer.diagnostics_update_count()
 275                || buffer.trailing_excerpt_update_count()
 276                    != new_buffer.trailing_excerpt_update_count()
 277            {
 278                self.version.fetch_add(1, SeqCst);
 279            }
 280            *buffer = new_buffer;
 281            Vec::new()
 282        } else {
 283            let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 284
 285            let mut new_transforms = SumTree::new();
 286            let mut transforms = self.transforms.lock();
 287            let mut cursor = transforms.cursor::<usize>();
 288            cursor.seek(&0, Bias::Right, &());
 289
 290            while let Some(mut edit) = buffer_edits_iter.next() {
 291                new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 292                edit.new.start -= edit.old.start - cursor.start();
 293                edit.old.start = *cursor.start();
 294
 295                cursor.seek(&edit.old.end, Bias::Right, &());
 296                cursor.next(&());
 297
 298                let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 299                loop {
 300                    edit.old.end = *cursor.start();
 301
 302                    if let Some(next_edit) = buffer_edits_iter.peek() {
 303                        if next_edit.old.start > edit.old.end {
 304                            break;
 305                        }
 306
 307                        let next_edit = buffer_edits_iter.next().unwrap();
 308                        delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 309
 310                        if next_edit.old.end >= edit.old.end {
 311                            edit.old.end = next_edit.old.end;
 312                            cursor.seek(&edit.old.end, Bias::Right, &());
 313                            cursor.next(&());
 314                        }
 315                    } else {
 316                        break;
 317                    }
 318                }
 319
 320                edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 321
 322                let anchor = new_buffer.anchor_before(edit.new.start);
 323                let mut folds_cursor = self.folds.cursor::<Fold>();
 324                folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &new_buffer);
 325
 326                let mut folds = iter::from_fn({
 327                    let buffer = &new_buffer;
 328                    move || {
 329                        let item = folds_cursor
 330                            .item()
 331                            .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 332                        folds_cursor.next(buffer);
 333                        item
 334                    }
 335                })
 336                .peekable();
 337
 338                while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 339                    let mut fold = folds.next().unwrap();
 340                    let sum = new_transforms.summary();
 341
 342                    assert!(fold.start >= sum.input.bytes);
 343
 344                    while folds
 345                        .peek()
 346                        .map_or(false, |next_fold| next_fold.start <= fold.end)
 347                    {
 348                        let next_fold = folds.next().unwrap();
 349                        if next_fold.end > fold.end {
 350                            fold.end = next_fold.end;
 351                        }
 352                    }
 353
 354                    if fold.start > sum.input.bytes {
 355                        let text_summary = new_buffer
 356                            .text_summary_for_range::<TextSummary, _>(sum.input.bytes..fold.start);
 357                        new_transforms.push(
 358                            Transform {
 359                                summary: TransformSummary {
 360                                    output: text_summary.clone(),
 361                                    input: text_summary,
 362                                },
 363                                output_text: None,
 364                            },
 365                            &(),
 366                        );
 367                    }
 368
 369                    if fold.end > fold.start {
 370                        let output_text = "…";
 371                        let chars = output_text.chars().count() as u32;
 372                        let lines = Point::new(0, output_text.len() as u32);
 373                        let lines_utf16 =
 374                            PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 375                        new_transforms.push(
 376                            Transform {
 377                                summary: TransformSummary {
 378                                    output: TextSummary {
 379                                        bytes: output_text.len(),
 380                                        lines,
 381                                        lines_utf16,
 382                                        first_line_chars: chars,
 383                                        last_line_chars: chars,
 384                                        longest_row: 0,
 385                                        longest_row_chars: chars,
 386                                    },
 387                                    input: new_buffer.text_summary_for_range(fold.start..fold.end),
 388                                },
 389                                output_text: Some(output_text),
 390                            },
 391                            &(),
 392                        );
 393                    }
 394                }
 395
 396                let sum = new_transforms.summary();
 397                if sum.input.bytes < edit.new.end {
 398                    let text_summary = new_buffer
 399                        .text_summary_for_range::<TextSummary, _>(sum.input.bytes..edit.new.end);
 400                    new_transforms.push(
 401                        Transform {
 402                            summary: TransformSummary {
 403                                output: text_summary.clone(),
 404                                input: text_summary,
 405                            },
 406                            output_text: None,
 407                        },
 408                        &(),
 409                    );
 410                }
 411            }
 412
 413            new_transforms.push_tree(cursor.suffix(&()), &());
 414            if new_transforms.is_empty() {
 415                let text_summary = new_buffer.text_summary();
 416                new_transforms.push(
 417                    Transform {
 418                        summary: TransformSummary {
 419                            output: text_summary.clone(),
 420                            input: text_summary,
 421                        },
 422                        output_text: None,
 423                    },
 424                    &(),
 425                );
 426            }
 427
 428            drop(cursor);
 429
 430            let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 431            {
 432                let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 433                let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 434
 435                for mut edit in buffer_edits {
 436                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 437                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 438                        edit.old.start = old_transforms.start().0;
 439                    }
 440                    let old_start =
 441                        old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 442
 443                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 444                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 445                        old_transforms.next(&());
 446                        edit.old.end = old_transforms.start().0;
 447                    }
 448                    let old_end =
 449                        old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 450
 451                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 452                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 453                        edit.new.start = new_transforms.start().0;
 454                    }
 455                    let new_start =
 456                        new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 457
 458                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 459                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 460                        new_transforms.next(&());
 461                        edit.new.end = new_transforms.start().0;
 462                    }
 463                    let new_end =
 464                        new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 465
 466                    fold_edits.push(FoldEdit {
 467                        old: FoldOffset(old_start)..FoldOffset(old_end),
 468                        new: FoldOffset(new_start)..FoldOffset(new_end),
 469                    });
 470                }
 471
 472                consolidate_fold_edits(&mut fold_edits);
 473            }
 474
 475            *transforms = new_transforms;
 476            *self.buffer.lock() = new_buffer;
 477            self.version.fetch_add(1, SeqCst);
 478            fold_edits
 479        }
 480    }
 481}
 482
 483#[derive(Clone)]
 484pub struct FoldSnapshot {
 485    transforms: SumTree<Transform>,
 486    folds: SumTree<Fold>,
 487    buffer_snapshot: MultiBufferSnapshot,
 488    pub version: usize,
 489}
 490
 491impl FoldSnapshot {
 492    pub fn buffer_snapshot(&self) -> &MultiBufferSnapshot {
 493        &self.buffer_snapshot
 494    }
 495
 496    #[cfg(test)]
 497    pub fn text(&self) -> String {
 498        self.chunks(FoldOffset(0)..self.len(), false, None)
 499            .map(|c| c.text)
 500            .collect()
 501    }
 502
 503    #[cfg(test)]
 504    pub fn fold_count(&self) -> usize {
 505        self.folds.items(&self.buffer_snapshot).len()
 506    }
 507
 508    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 509        let mut summary = TextSummary::default();
 510
 511        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 512        cursor.seek(&range.start, Bias::Right, &());
 513        if let Some(transform) = cursor.item() {
 514            let start_in_transform = range.start.0 - cursor.start().0 .0;
 515            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 516            if let Some(output_text) = transform.output_text {
 517                summary = TextSummary::from(
 518                    &output_text
 519                        [start_in_transform.column as usize..end_in_transform.column as usize],
 520                );
 521            } else {
 522                let buffer_start = cursor.start().1 + start_in_transform;
 523                let buffer_end = cursor.start().1 + end_in_transform;
 524                summary = self
 525                    .buffer_snapshot
 526                    .text_summary_for_range(buffer_start..buffer_end);
 527            }
 528        }
 529
 530        if range.end > cursor.end(&()).0 {
 531            cursor.next(&());
 532            summary += &cursor
 533                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 534                .output;
 535            if let Some(transform) = cursor.item() {
 536                let end_in_transform = range.end.0 - cursor.start().0 .0;
 537                if let Some(output_text) = transform.output_text {
 538                    summary += TextSummary::from(&output_text[..end_in_transform.column as usize]);
 539                } else {
 540                    let buffer_start = cursor.start().1;
 541                    let buffer_end = cursor.start().1 + end_in_transform;
 542                    summary += self
 543                        .buffer_snapshot
 544                        .text_summary_for_range::<TextSummary, _>(buffer_start..buffer_end);
 545                }
 546            }
 547        }
 548
 549        summary
 550    }
 551
 552    pub fn to_fold_point(&self, point: Point, bias: Bias) -> FoldPoint {
 553        let mut cursor = self.transforms.cursor::<(Point, FoldPoint)>();
 554        cursor.seek(&point, Bias::Right, &());
 555        if cursor.item().map_or(false, |t| t.is_fold()) {
 556            if bias == Bias::Left || point == cursor.start().0 {
 557                cursor.start().1
 558            } else {
 559                cursor.end(&()).1
 560            }
 561        } else {
 562            let overshoot = point - cursor.start().0;
 563            FoldPoint(cmp::min(
 564                cursor.start().1 .0 + overshoot,
 565                cursor.end(&()).1 .0,
 566            ))
 567        }
 568    }
 569
 570    pub fn len(&self) -> FoldOffset {
 571        FoldOffset(self.transforms.summary().output.bytes)
 572    }
 573
 574    pub fn line_len(&self, row: u32) -> u32 {
 575        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 576        let line_end = if row >= self.max_point().row() {
 577            self.len().0
 578        } else {
 579            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 580        };
 581        (line_end - line_start) as u32
 582    }
 583
 584    pub fn buffer_rows(&self, start_row: u32) -> FoldBufferRows {
 585        if start_row > self.transforms.summary().output.lines.row {
 586            panic!("invalid display row {}", start_row);
 587        }
 588
 589        let fold_point = FoldPoint::new(start_row, 0);
 590        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 591        cursor.seek(&fold_point, Bias::Left, &());
 592
 593        let overshoot = fold_point.0 - cursor.start().0 .0;
 594        let buffer_point = cursor.start().1 + overshoot;
 595        let input_buffer_rows = self.buffer_snapshot.buffer_rows(buffer_point.row);
 596
 597        FoldBufferRows {
 598            fold_point,
 599            input_buffer_rows,
 600            cursor,
 601        }
 602    }
 603
 604    pub fn max_point(&self) -> FoldPoint {
 605        FoldPoint(self.transforms.summary().output.lines)
 606    }
 607
 608    #[cfg(test)]
 609    pub fn longest_row(&self) -> u32 {
 610        self.transforms.summary().output.longest_row
 611    }
 612
 613    pub fn folds_in_range<'a, T>(
 614        &'a self,
 615        range: Range<T>,
 616    ) -> impl Iterator<Item = &'a Range<Anchor>>
 617    where
 618        T: ToOffset,
 619    {
 620        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 621        iter::from_fn(move || {
 622            let item = folds.item().map(|f| &f.0);
 623            folds.next(&self.buffer_snapshot);
 624            item
 625        })
 626    }
 627
 628    pub fn intersects_fold<T>(&self, offset: T) -> bool
 629    where
 630        T: ToOffset,
 631    {
 632        let offset = offset.to_offset(&self.buffer_snapshot);
 633        let mut cursor = self.transforms.cursor::<usize>();
 634        cursor.seek(&offset, Bias::Right, &());
 635        cursor.item().map_or(false, |t| t.output_text.is_some())
 636    }
 637
 638    pub fn is_line_folded(&self, output_row: u32) -> bool {
 639        let mut cursor = self.transforms.cursor::<FoldPoint>();
 640        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 641        while let Some(transform) = cursor.item() {
 642            if transform.output_text.is_some() {
 643                return true;
 644            }
 645            if cursor.end(&()).row() == output_row {
 646                cursor.next(&())
 647            } else {
 648                break;
 649            }
 650        }
 651        false
 652    }
 653
 654    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 655        let start = start.to_offset(self);
 656        self.chunks(start..self.len(), false, None)
 657            .flat_map(|chunk| chunk.text.chars())
 658    }
 659
 660    pub fn chunks<'a>(
 661        &'a self,
 662        range: Range<FoldOffset>,
 663        language_aware: bool,
 664        text_highlights: Option<&'a TextHighlights>,
 665    ) -> FoldChunks<'a> {
 666        let mut highlight_endpoints = Vec::new();
 667        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 668
 669        let buffer_end = {
 670            transform_cursor.seek(&range.end, Bias::Right, &());
 671            let overshoot = range.end.0 - transform_cursor.start().0 .0;
 672            transform_cursor.start().1 + overshoot
 673        };
 674
 675        let buffer_start = {
 676            transform_cursor.seek(&range.start, Bias::Right, &());
 677            let overshoot = range.start.0 - transform_cursor.start().0 .0;
 678            transform_cursor.start().1 + overshoot
 679        };
 680
 681        if let Some(text_highlights) = text_highlights {
 682            if !text_highlights.is_empty() {
 683                while transform_cursor.start().0 < range.end {
 684                    if !transform_cursor.item().unwrap().is_fold() {
 685                        let transform_start = self
 686                            .buffer_snapshot
 687                            .anchor_after(cmp::max(buffer_start, transform_cursor.start().1));
 688
 689                        let transform_end = {
 690                            let overshoot = range.end.0 - transform_cursor.start().0 .0;
 691                            self.buffer_snapshot.anchor_before(cmp::min(
 692                                transform_cursor.end(&()).1,
 693                                transform_cursor.start().1 + overshoot,
 694                            ))
 695                        };
 696
 697                        for (tag, highlights) in text_highlights.iter() {
 698                            let style = highlights.0;
 699                            let ranges = &highlights.1;
 700
 701                            let start_ix = match ranges.binary_search_by(|probe| {
 702                                let cmp = probe
 703                                    .end
 704                                    .cmp(&transform_start, &self.buffer_snapshot())
 705                                    .unwrap();
 706                                if cmp.is_gt() {
 707                                    Ordering::Greater
 708                                } else {
 709                                    Ordering::Less
 710                                }
 711                            }) {
 712                                Ok(i) | Err(i) => i,
 713                            };
 714                            for range in &ranges[start_ix..] {
 715                                if range
 716                                    .start
 717                                    .cmp(&transform_end, &self.buffer_snapshot)
 718                                    .unwrap()
 719                                    .is_ge()
 720                                {
 721                                    break;
 722                                }
 723
 724                                highlight_endpoints.push(HighlightEndpoint {
 725                                    offset: range.start.to_offset(&self.buffer_snapshot),
 726                                    is_start: true,
 727                                    tag: *tag,
 728                                    style,
 729                                });
 730                                highlight_endpoints.push(HighlightEndpoint {
 731                                    offset: range.end.to_offset(&self.buffer_snapshot),
 732                                    is_start: false,
 733                                    tag: *tag,
 734                                    style,
 735                                });
 736                            }
 737                        }
 738                    }
 739
 740                    transform_cursor.next(&());
 741                }
 742                highlight_endpoints.sort();
 743                transform_cursor.seek(&range.start, Bias::Right, &());
 744            }
 745        }
 746
 747        FoldChunks {
 748            transform_cursor,
 749            buffer_chunks: self
 750                .buffer_snapshot
 751                .chunks(buffer_start..buffer_end, language_aware),
 752            buffer_chunk: None,
 753            buffer_offset: buffer_start,
 754            output_offset: range.start.0,
 755            max_output_offset: range.end.0,
 756            highlight_endpoints: highlight_endpoints.into_iter().peekable(),
 757            active_highlights: Default::default(),
 758        }
 759    }
 760
 761    #[cfg(test)]
 762    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 763        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 764        cursor.seek(&offset, Bias::Right, &());
 765        if let Some(transform) = cursor.item() {
 766            let transform_start = cursor.start().0 .0;
 767            if transform.output_text.is_some() {
 768                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 769                    FoldOffset(transform_start)
 770                } else {
 771                    FoldOffset(cursor.end(&()).0 .0)
 772                }
 773            } else {
 774                let overshoot = offset.0 - transform_start;
 775                let buffer_offset = cursor.start().1 + overshoot;
 776                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 777                FoldOffset(
 778                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 779                        as usize,
 780                )
 781            }
 782        } else {
 783            FoldOffset(self.transforms.summary().output.bytes)
 784        }
 785    }
 786
 787    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 788        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 789        cursor.seek(&point, Bias::Right, &());
 790        if let Some(transform) = cursor.item() {
 791            let transform_start = cursor.start().0 .0;
 792            if transform.output_text.is_some() {
 793                if point.0 == transform_start || matches!(bias, Bias::Left) {
 794                    FoldPoint(transform_start)
 795                } else {
 796                    FoldPoint(cursor.end(&()).0 .0)
 797                }
 798            } else {
 799                let overshoot = point.0 - transform_start;
 800                let buffer_position = cursor.start().1 + overshoot;
 801                let clipped_buffer_position =
 802                    self.buffer_snapshot.clip_point(buffer_position, bias);
 803                FoldPoint(cursor.start().0 .0 + (clipped_buffer_position - cursor.start().1))
 804            }
 805        } else {
 806            FoldPoint(self.transforms.summary().output.lines)
 807        }
 808    }
 809}
 810
 811fn intersecting_folds<'a, T>(
 812    buffer: &'a MultiBufferSnapshot,
 813    folds: &'a SumTree<Fold>,
 814    range: Range<T>,
 815    inclusive: bool,
 816) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 817where
 818    T: ToOffset,
 819{
 820    let start = buffer.anchor_before(range.start.to_offset(buffer));
 821    let end = buffer.anchor_after(range.end.to_offset(buffer));
 822    let mut cursor = folds.filter::<_, usize>(move |summary| {
 823        let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 824        let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 825
 826        if inclusive {
 827            start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 828        } else {
 829            start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 830        }
 831    });
 832    cursor.next(buffer);
 833    cursor
 834}
 835
 836fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 837    edits.sort_unstable_by(|a, b| {
 838        a.old
 839            .start
 840            .cmp(&b.old.start)
 841            .then_with(|| b.old.end.cmp(&a.old.end))
 842    });
 843
 844    let mut i = 1;
 845    while i < edits.len() {
 846        let edit = edits[i].clone();
 847        let prev_edit = &mut edits[i - 1];
 848        if prev_edit.old.end >= edit.old.start {
 849            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 850            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 851            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 852            edits.remove(i);
 853            continue;
 854        }
 855        i += 1;
 856    }
 857}
 858
 859fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 860    edits.sort_unstable_by(|a, b| {
 861        a.old
 862            .start
 863            .cmp(&b.old.start)
 864            .then_with(|| b.old.end.cmp(&a.old.end))
 865    });
 866
 867    let mut i = 1;
 868    while i < edits.len() {
 869        let edit = edits[i].clone();
 870        let prev_edit = &mut edits[i - 1];
 871        if prev_edit.old.end >= edit.old.start {
 872            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 873            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 874            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 875            edits.remove(i);
 876            continue;
 877        }
 878        i += 1;
 879    }
 880}
 881
 882#[derive(Clone, Debug, Default, Eq, PartialEq)]
 883struct Transform {
 884    summary: TransformSummary,
 885    output_text: Option<&'static str>,
 886}
 887
 888impl Transform {
 889    fn is_fold(&self) -> bool {
 890        self.output_text.is_some()
 891    }
 892}
 893
 894#[derive(Clone, Debug, Default, Eq, PartialEq)]
 895struct TransformSummary {
 896    output: TextSummary,
 897    input: TextSummary,
 898}
 899
 900impl sum_tree::Item for Transform {
 901    type Summary = TransformSummary;
 902
 903    fn summary(&self) -> Self::Summary {
 904        self.summary.clone()
 905    }
 906}
 907
 908impl sum_tree::Summary for TransformSummary {
 909    type Context = ();
 910
 911    fn add_summary(&mut self, other: &Self, _: &()) {
 912        self.input += &other.input;
 913        self.output += &other.output;
 914    }
 915}
 916
 917#[derive(Clone, Debug)]
 918struct Fold(Range<Anchor>);
 919
 920impl Default for Fold {
 921    fn default() -> Self {
 922        Self(Anchor::min()..Anchor::max())
 923    }
 924}
 925
 926impl sum_tree::Item for Fold {
 927    type Summary = FoldSummary;
 928
 929    fn summary(&self) -> Self::Summary {
 930        FoldSummary {
 931            start: self.0.start.clone(),
 932            end: self.0.end.clone(),
 933            min_start: self.0.start.clone(),
 934            max_end: self.0.end.clone(),
 935            count: 1,
 936        }
 937    }
 938}
 939
 940#[derive(Clone, Debug)]
 941struct FoldSummary {
 942    start: Anchor,
 943    end: Anchor,
 944    min_start: Anchor,
 945    max_end: Anchor,
 946    count: usize,
 947}
 948
 949impl Default for FoldSummary {
 950    fn default() -> Self {
 951        Self {
 952            start: Anchor::min(),
 953            end: Anchor::max(),
 954            min_start: Anchor::max(),
 955            max_end: Anchor::min(),
 956            count: 0,
 957        }
 958    }
 959}
 960
 961impl sum_tree::Summary for FoldSummary {
 962    type Context = MultiBufferSnapshot;
 963
 964    fn add_summary(&mut self, other: &Self, buffer: &MultiBufferSnapshot) {
 965        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 966            self.min_start = other.min_start.clone();
 967        }
 968        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 969            self.max_end = other.max_end.clone();
 970        }
 971
 972        #[cfg(debug_assertions)]
 973        {
 974            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 975            assert!(start_comparison <= Ordering::Equal);
 976            if start_comparison == Ordering::Equal {
 977                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 978            }
 979        }
 980
 981        self.start = other.start.clone();
 982        self.end = other.end.clone();
 983        self.count += other.count;
 984    }
 985}
 986
 987impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 988    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 989        self.0.start = summary.start.clone();
 990        self.0.end = summary.end.clone();
 991    }
 992}
 993
 994impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 995    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
 996        self.0.cmp(&other.0, buffer).unwrap()
 997    }
 998}
 999
1000impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
1001    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1002        *self += summary.count;
1003    }
1004}
1005
1006pub struct FoldBufferRows<'a> {
1007    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
1008    input_buffer_rows: MultiBufferRows<'a>,
1009    fold_point: FoldPoint,
1010}
1011
1012impl<'a> Iterator for FoldBufferRows<'a> {
1013    type Item = Option<u32>;
1014
1015    fn next(&mut self) -> Option<Self::Item> {
1016        let mut traversed_fold = false;
1017        while self.fold_point > self.cursor.end(&()).0 {
1018            self.cursor.next(&());
1019            traversed_fold = true;
1020            if self.cursor.item().is_none() {
1021                break;
1022            }
1023        }
1024
1025        if self.cursor.item().is_some() {
1026            if traversed_fold {
1027                self.input_buffer_rows.seek(self.cursor.start().1.row);
1028                self.input_buffer_rows.next();
1029            }
1030            *self.fold_point.row_mut() += 1;
1031            self.input_buffer_rows.next()
1032        } else {
1033            None
1034        }
1035    }
1036}
1037
1038pub struct FoldChunks<'a> {
1039    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
1040    buffer_chunks: MultiBufferChunks<'a>,
1041    buffer_chunk: Option<(usize, Chunk<'a>)>,
1042    buffer_offset: usize,
1043    output_offset: usize,
1044    max_output_offset: usize,
1045    highlight_endpoints: Peekable<vec::IntoIter<HighlightEndpoint>>,
1046    active_highlights: BTreeMap<Option<TypeId>, HighlightStyle>,
1047}
1048
1049impl<'a> Iterator for FoldChunks<'a> {
1050    type Item = Chunk<'a>;
1051
1052    fn next(&mut self) -> Option<Self::Item> {
1053        if self.output_offset >= self.max_output_offset {
1054            return None;
1055        }
1056
1057        let transform = if let Some(item) = self.transform_cursor.item() {
1058            item
1059        } else {
1060            return None;
1061        };
1062
1063        // If we're in a fold, then return the fold's display text and
1064        // advance the transform and buffer cursors to the end of the fold.
1065        if let Some(output_text) = transform.output_text {
1066            self.buffer_chunk.take();
1067            self.buffer_offset += transform.summary.input.bytes;
1068            self.buffer_chunks.seek(self.buffer_offset);
1069
1070            while self.buffer_offset >= self.transform_cursor.end(&()).1
1071                && self.transform_cursor.item().is_some()
1072            {
1073                self.transform_cursor.next(&());
1074            }
1075
1076            self.output_offset += output_text.len();
1077            return Some(Chunk {
1078                text: output_text,
1079                syntax_highlight_id: None,
1080                highlight_style: None,
1081                diagnostic_severity: None,
1082                is_unnecessary: false,
1083            });
1084        }
1085
1086        let mut next_highlight_endpoint = usize::MAX;
1087        while let Some(endpoint) = self.highlight_endpoints.peek().copied() {
1088            if endpoint.offset <= self.buffer_offset {
1089                if endpoint.is_start {
1090                    self.active_highlights.insert(endpoint.tag, endpoint.style);
1091                } else {
1092                    self.active_highlights.remove(&endpoint.tag);
1093                }
1094                self.highlight_endpoints.next();
1095            } else {
1096                next_highlight_endpoint = endpoint.offset;
1097                break;
1098            }
1099        }
1100
1101        // Retrieve a chunk from the current location in the buffer.
1102        if self.buffer_chunk.is_none() {
1103            let chunk_offset = self.buffer_chunks.offset();
1104            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
1105        }
1106
1107        // Otherwise, take a chunk from the buffer's text.
1108        if let Some((buffer_chunk_start, mut chunk)) = self.buffer_chunk {
1109            let buffer_chunk_end = buffer_chunk_start + chunk.text.len();
1110            let transform_end = self.transform_cursor.end(&()).1;
1111            let chunk_end = buffer_chunk_end
1112                .min(transform_end)
1113                .min(next_highlight_endpoint);
1114
1115            chunk.text = &chunk.text
1116                [self.buffer_offset - buffer_chunk_start..chunk_end - buffer_chunk_start];
1117
1118            if !self.active_highlights.is_empty() {
1119                let mut highlight_style = HighlightStyle::default();
1120                for active_highlight in self.active_highlights.values() {
1121                    highlight_style.highlight(*active_highlight);
1122                }
1123                chunk.highlight_style = Some(highlight_style);
1124            }
1125
1126            if chunk_end == transform_end {
1127                self.transform_cursor.next(&());
1128            } else if chunk_end == buffer_chunk_end {
1129                self.buffer_chunk.take();
1130            }
1131
1132            self.buffer_offset = chunk_end;
1133            self.output_offset += chunk.text.len();
1134            return Some(chunk);
1135        }
1136
1137        None
1138    }
1139}
1140
1141#[derive(Copy, Clone, Eq, PartialEq)]
1142struct HighlightEndpoint {
1143    offset: usize,
1144    is_start: bool,
1145    tag: Option<TypeId>,
1146    style: HighlightStyle,
1147}
1148
1149impl PartialOrd for HighlightEndpoint {
1150    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
1151        Some(self.cmp(other))
1152    }
1153}
1154
1155impl Ord for HighlightEndpoint {
1156    fn cmp(&self, other: &Self) -> Ordering {
1157        self.offset
1158            .cmp(&other.offset)
1159            .then_with(|| other.is_start.cmp(&self.is_start))
1160    }
1161}
1162
1163#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1164pub struct FoldOffset(pub usize);
1165
1166impl FoldOffset {
1167    pub fn to_point(&self, snapshot: &FoldSnapshot) -> FoldPoint {
1168        let mut cursor = snapshot
1169            .transforms
1170            .cursor::<(FoldOffset, TransformSummary)>();
1171        cursor.seek(self, Bias::Right, &());
1172        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1173            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1174        } else {
1175            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1176            let buffer_point = snapshot.buffer_snapshot.offset_to_point(buffer_offset);
1177            buffer_point - cursor.start().1.input.lines
1178        };
1179        FoldPoint(cursor.start().1.output.lines + overshoot)
1180    }
1181}
1182
1183impl Sub for FoldOffset {
1184    type Output = Self;
1185
1186    fn sub(self, rhs: Self) -> Self::Output {
1187        Self(self.0 - rhs.0)
1188    }
1189}
1190
1191impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1192    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1193        self.0 += &summary.output.bytes;
1194    }
1195}
1196
1197impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1198    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1199        *self += &summary.input.lines;
1200    }
1201}
1202
1203impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1204    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1205        *self += &summary.input.bytes;
1206    }
1207}
1208
1209pub type FoldEdit = Edit<FoldOffset>;
1210
1211#[cfg(test)]
1212mod tests {
1213    use super::*;
1214    use crate::{MultiBuffer, ToPoint};
1215    use rand::prelude::*;
1216    use std::{cmp::Reverse, env, mem, sync::Arc};
1217    use sum_tree::TreeMap;
1218    use text::RandomCharIter;
1219    use util::test::sample_text;
1220    use Bias::{Left, Right};
1221
1222    #[gpui::test]
1223    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1224        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1225        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1226        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1227        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1228
1229        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1230        let (snapshot2, edits) = writer.fold(vec![
1231            Point::new(0, 2)..Point::new(2, 2),
1232            Point::new(2, 4)..Point::new(4, 1),
1233        ]);
1234        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1235        assert_eq!(
1236            edits,
1237            &[
1238                FoldEdit {
1239                    old: FoldOffset(2)..FoldOffset(16),
1240                    new: FoldOffset(2)..FoldOffset(5),
1241                },
1242                FoldEdit {
1243                    old: FoldOffset(18)..FoldOffset(29),
1244                    new: FoldOffset(7)..FoldOffset(10)
1245                },
1246            ]
1247        );
1248
1249        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1250            buffer.edit(
1251                vec![
1252                    Point::new(0, 0)..Point::new(0, 1),
1253                    Point::new(2, 3)..Point::new(2, 3),
1254                ],
1255                "123",
1256                cx,
1257            );
1258            buffer.snapshot(cx)
1259        });
1260        let (snapshot3, edits) =
1261            map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1262        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1263        assert_eq!(
1264            edits,
1265            &[
1266                FoldEdit {
1267                    old: FoldOffset(0)..FoldOffset(1),
1268                    new: FoldOffset(0)..FoldOffset(3),
1269                },
1270                FoldEdit {
1271                    old: FoldOffset(6)..FoldOffset(6),
1272                    new: FoldOffset(8)..FoldOffset(11),
1273                },
1274            ]
1275        );
1276
1277        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1278            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1279            buffer.snapshot(cx)
1280        });
1281        let (snapshot4, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1282        assert_eq!(snapshot4.text(), "123a…c123456eee");
1283
1284        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1285        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1286        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1287        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1288    }
1289
1290    #[gpui::test]
1291    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1292        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1293        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1294        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1295
1296        {
1297            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1298
1299            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1300            writer.fold(vec![5..8]);
1301            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1302            assert_eq!(snapshot.text(), "abcde…ijkl");
1303
1304            // Create an fold adjacent to the start of the first fold.
1305            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1306            writer.fold(vec![0..1, 2..5]);
1307            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1308            assert_eq!(snapshot.text(), "…b…ijkl");
1309
1310            // Create an fold adjacent to the end of the first fold.
1311            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1312            writer.fold(vec![11..11, 8..10]);
1313            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1314            assert_eq!(snapshot.text(), "…b…kl");
1315        }
1316
1317        {
1318            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1319
1320            // Create two adjacent folds.
1321            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1322            writer.fold(vec![0..2, 2..5]);
1323            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1324            assert_eq!(snapshot.text(), "…fghijkl");
1325
1326            // Edit within one of the folds.
1327            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1328                buffer.edit(vec![0..1], "12345", cx);
1329                buffer.snapshot(cx)
1330            });
1331            let (snapshot, _) =
1332                map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1333            assert_eq!(snapshot.text(), "12345…fghijkl");
1334        }
1335    }
1336
1337    #[gpui::test]
1338    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1339        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1340        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1341        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1342        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1343        writer.fold(vec![
1344            Point::new(0, 2)..Point::new(2, 2),
1345            Point::new(0, 4)..Point::new(1, 0),
1346            Point::new(1, 2)..Point::new(3, 2),
1347            Point::new(3, 1)..Point::new(4, 1),
1348        ]);
1349        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1350        assert_eq!(snapshot.text(), "aa…eeeee");
1351    }
1352
1353    #[gpui::test]
1354    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1355        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1356        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1357        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1358        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1359
1360        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1361        writer.fold(vec![
1362            Point::new(0, 2)..Point::new(2, 2),
1363            Point::new(3, 1)..Point::new(4, 1),
1364        ]);
1365        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1366        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1367
1368        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1369            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1370            buffer.snapshot(cx)
1371        });
1372        let (snapshot, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1373        assert_eq!(snapshot.text(), "aa…eeeee");
1374    }
1375
1376    #[gpui::test]
1377    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1378        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1379        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1380        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1381
1382        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1383        writer.fold(vec![
1384            Point::new(0, 2)..Point::new(2, 2),
1385            Point::new(0, 4)..Point::new(1, 0),
1386            Point::new(1, 2)..Point::new(3, 2),
1387            Point::new(3, 1)..Point::new(4, 1),
1388        ]);
1389        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1390        let fold_ranges = snapshot
1391            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1392            .map(|fold| fold.start.to_point(&buffer_snapshot)..fold.end.to_point(&buffer_snapshot))
1393            .collect::<Vec<_>>();
1394        assert_eq!(
1395            fold_ranges,
1396            vec![
1397                Point::new(0, 2)..Point::new(2, 2),
1398                Point::new(1, 2)..Point::new(3, 2)
1399            ]
1400        );
1401    }
1402
1403    #[gpui::test(iterations = 100)]
1404    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1405        let operations = env::var("OPERATIONS")
1406            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1407            .unwrap_or(10);
1408
1409        let len = rng.gen_range(0..10);
1410        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1411        let buffer = if rng.gen() {
1412            MultiBuffer::build_simple(&text, cx)
1413        } else {
1414            MultiBuffer::build_random(&mut rng, cx)
1415        };
1416        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1417        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1418
1419        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1420        let mut snapshot_edits = Vec::new();
1421
1422        let mut highlights = TreeMap::default();
1423        let highlight_count = rng.gen_range(0_usize..10);
1424        let mut highlight_ranges = (0..highlight_count)
1425            .map(|_| buffer_snapshot.random_byte_range(0, &mut rng))
1426            .collect::<Vec<_>>();
1427        highlight_ranges.sort_by_key(|range| (range.start, Reverse(range.end)));
1428        log::info!("highlighting ranges {:?}", highlight_ranges);
1429        let highlight_ranges = highlight_ranges
1430            .into_iter()
1431            .map(|range| {
1432                buffer_snapshot.anchor_before(range.start)..buffer_snapshot.anchor_after(range.end)
1433            })
1434            .collect::<Vec<_>>();
1435
1436        highlights.insert(
1437            Some(TypeId::of::<()>()),
1438            Arc::new((HighlightStyle::default(), highlight_ranges)),
1439        );
1440
1441        for _ in 0..operations {
1442            log::info!("text: {:?}", buffer_snapshot.text());
1443            let mut buffer_edits = Vec::new();
1444            match rng.gen_range(0..=100) {
1445                0..=59 => {
1446                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1447                }
1448                _ => buffer.update(cx, |buffer, cx| {
1449                    let subscription = buffer.subscribe();
1450                    let edit_count = rng.gen_range(1..=5);
1451                    buffer.randomly_mutate(&mut rng, edit_count, cx);
1452                    buffer_snapshot = buffer.snapshot(cx);
1453                    let edits = subscription.consume().into_inner();
1454                    log::info!("editing {:?}", edits);
1455                    buffer_edits.extend(edits);
1456                }),
1457            };
1458
1459            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1460            snapshot_edits.push((snapshot.clone(), edits));
1461
1462            let mut expected_text: String = buffer_snapshot.text().to_string();
1463            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1464                expected_text.replace_range(fold_range.start..fold_range.end, "…");
1465            }
1466
1467            assert_eq!(snapshot.text(), expected_text);
1468            log::info!(
1469                "fold text {:?} ({} lines)",
1470                expected_text,
1471                expected_text.matches('\n').count() + 1
1472            );
1473
1474            let mut prev_row = 0;
1475            let mut expected_buffer_rows = Vec::new();
1476            for fold_range in map.merged_fold_ranges().into_iter() {
1477                let fold_start = buffer_snapshot.offset_to_point(fold_range.start).row;
1478                let fold_end = buffer_snapshot.offset_to_point(fold_range.end).row;
1479                expected_buffer_rows.extend(
1480                    buffer_snapshot
1481                        .buffer_rows(prev_row)
1482                        .take((1 + fold_start - prev_row) as usize),
1483                );
1484                prev_row = 1 + fold_end;
1485            }
1486            expected_buffer_rows.extend(buffer_snapshot.buffer_rows(prev_row));
1487
1488            assert_eq!(
1489                expected_buffer_rows.len(),
1490                expected_text.matches('\n').count() + 1,
1491                "wrong expected buffer rows {:?}. text: {:?}",
1492                expected_buffer_rows,
1493                expected_text
1494            );
1495
1496            for (output_row, line) in expected_text.lines().enumerate() {
1497                let line_len = snapshot.line_len(output_row as u32);
1498                assert_eq!(line_len, line.len() as u32);
1499            }
1500
1501            let longest_row = snapshot.longest_row();
1502            let longest_char_column = expected_text
1503                .split('\n')
1504                .nth(longest_row as usize)
1505                .unwrap()
1506                .chars()
1507                .count();
1508            let mut fold_point = FoldPoint::new(0, 0);
1509            let mut fold_offset = FoldOffset(0);
1510            let mut char_column = 0;
1511            for c in expected_text.chars() {
1512                let buffer_point = fold_point.to_buffer_point(&snapshot);
1513                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1514                assert_eq!(
1515                    snapshot.to_fold_point(buffer_point, Right),
1516                    fold_point,
1517                    "{:?} -> fold point",
1518                    buffer_point,
1519                );
1520                assert_eq!(
1521                    fold_point.to_buffer_offset(&snapshot),
1522                    buffer_offset,
1523                    "fold_point.to_buffer_offset({:?})",
1524                    fold_point,
1525                );
1526                assert_eq!(
1527                    fold_point.to_offset(&snapshot),
1528                    fold_offset,
1529                    "fold_point.to_offset({:?})",
1530                    fold_point,
1531                );
1532
1533                if c == '\n' {
1534                    *fold_point.row_mut() += 1;
1535                    *fold_point.column_mut() = 0;
1536                    char_column = 0;
1537                } else {
1538                    *fold_point.column_mut() += c.len_utf8() as u32;
1539                    char_column += 1;
1540                }
1541                fold_offset.0 += c.len_utf8();
1542                if char_column > longest_char_column {
1543                    panic!(
1544                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1545                        longest_row,
1546                        longest_char_column,
1547                        fold_point.row(),
1548                        char_column
1549                    );
1550                }
1551            }
1552
1553            for _ in 0..5 {
1554                let mut start = snapshot
1555                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1556                let mut end = snapshot
1557                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1558                if start > end {
1559                    mem::swap(&mut start, &mut end);
1560                }
1561
1562                let text = &expected_text[start.0..end.0];
1563                assert_eq!(
1564                    snapshot
1565                        .chunks(start..end, false, Some(&highlights))
1566                        .map(|c| c.text)
1567                        .collect::<String>(),
1568                    text,
1569                );
1570            }
1571
1572            let mut fold_row = 0;
1573            while fold_row < expected_buffer_rows.len() as u32 {
1574                fold_row = snapshot
1575                    .clip_point(FoldPoint::new(fold_row, 0), Bias::Right)
1576                    .row();
1577                assert_eq!(
1578                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1579                    expected_buffer_rows[(fold_row as usize)..],
1580                    "wrong buffer rows starting at fold row {}",
1581                    fold_row,
1582                );
1583                fold_row += 1;
1584            }
1585
1586            for fold_range in map.merged_fold_ranges() {
1587                let fold_point =
1588                    snapshot.to_fold_point(fold_range.start.to_point(&buffer_snapshot), Right);
1589                assert!(snapshot.is_line_folded(fold_point.row()));
1590            }
1591
1592            for _ in 0..5 {
1593                let end =
1594                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1595                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1596                let expected_folds = map
1597                    .folds
1598                    .items(&buffer_snapshot)
1599                    .into_iter()
1600                    .filter(|fold| {
1601                        let start = buffer_snapshot.anchor_before(start);
1602                        let end = buffer_snapshot.anchor_after(end);
1603                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1604                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1605                                == Ordering::Greater
1606                    })
1607                    .map(|fold| fold.0)
1608                    .collect::<Vec<_>>();
1609
1610                assert_eq!(
1611                    snapshot
1612                        .folds_in_range(start..end)
1613                        .cloned()
1614                        .collect::<Vec<_>>(),
1615                    expected_folds
1616                );
1617            }
1618
1619            let text = snapshot.text();
1620            for _ in 0..5 {
1621                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1622                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1623                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1624                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1625                let mut start =
1626                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1627                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1628                if start > end {
1629                    mem::swap(&mut start, &mut end);
1630                }
1631
1632                let lines = start..end;
1633                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1634                assert_eq!(
1635                    snapshot.text_summary_for_range(lines),
1636                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1637                )
1638            }
1639
1640            let mut text = initial_snapshot.text();
1641            for (snapshot, edits) in snapshot_edits.drain(..) {
1642                let new_text = snapshot.text();
1643                for edit in edits {
1644                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1645                    let new_bytes = edit.new.start.0..edit.new.end.0;
1646                    text.replace_range(old_bytes, &new_text[new_bytes]);
1647                }
1648
1649                assert_eq!(text, new_text);
1650                initial_snapshot = snapshot;
1651            }
1652        }
1653    }
1654
1655    #[gpui::test]
1656    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1657        let text = sample_text(6, 6, 'a') + "\n";
1658        let buffer = MultiBuffer::build_simple(&text, cx);
1659
1660        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1661        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1662
1663        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1664        writer.fold(vec![
1665            Point::new(0, 2)..Point::new(2, 2),
1666            Point::new(3, 1)..Point::new(4, 1),
1667        ]);
1668
1669        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1670        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1671        assert_eq!(
1672            snapshot.buffer_rows(0).collect::<Vec<_>>(),
1673            [Some(0), Some(3), Some(5), Some(6)]
1674        );
1675        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [Some(6)]);
1676    }
1677
1678    impl FoldMap {
1679        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1680            let buffer = self.buffer.lock().clone();
1681            let mut folds = self.folds.items(&buffer);
1682            // Ensure sorting doesn't change how folds get merged and displayed.
1683            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1684            let mut fold_ranges = folds
1685                .iter()
1686                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1687                .peekable();
1688
1689            let mut merged_ranges = Vec::new();
1690            while let Some(mut fold_range) = fold_ranges.next() {
1691                while let Some(next_range) = fold_ranges.peek() {
1692                    if fold_range.end >= next_range.start {
1693                        if next_range.end > fold_range.end {
1694                            fold_range.end = next_range.end;
1695                        }
1696                        fold_ranges.next();
1697                    } else {
1698                        break;
1699                    }
1700                }
1701                if fold_range.end > fold_range.start {
1702                    merged_ranges.push(fold_range);
1703                }
1704            }
1705            merged_ranges
1706        }
1707
1708        pub fn randomly_mutate(
1709            &mut self,
1710            rng: &mut impl Rng,
1711        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1712            let mut snapshot_edits = Vec::new();
1713            match rng.gen_range(0..=100) {
1714                0..=39 if !self.folds.is_empty() => {
1715                    let buffer = self.buffer.lock().clone();
1716                    let mut to_unfold = Vec::new();
1717                    for _ in 0..rng.gen_range(1..=3) {
1718                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1719                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1720                        to_unfold.push(start..end);
1721                    }
1722                    log::info!("unfolding {:?}", to_unfold);
1723                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1724                    snapshot_edits.push((snapshot, edits));
1725                    let (snapshot, edits) = writer.fold(to_unfold);
1726                    snapshot_edits.push((snapshot, edits));
1727                }
1728                _ => {
1729                    let buffer = self.buffer.lock().clone();
1730                    let mut to_fold = Vec::new();
1731                    for _ in 0..rng.gen_range(1..=2) {
1732                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1733                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1734                        to_fold.push(start..end);
1735                    }
1736                    log::info!("folding {:?}", to_fold);
1737                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1738                    snapshot_edits.push((snapshot, edits));
1739                    let (snapshot, edits) = writer.fold(to_fold);
1740                    snapshot_edits.push((snapshot, edits));
1741                }
1742            }
1743            snapshot_edits
1744        }
1745    }
1746}