fold_map.rs

   1use gpui::{AppContext, ModelHandle};
   2use language::{
   3    Anchor, AnchorRangeExt, Buffer, HighlightId, HighlightedChunk, Point, PointUtf16, TextSummary,
   4    ToOffset,
   5};
   6use parking_lot::Mutex;
   7use std::{
   8    cmp::{self, Ordering},
   9    iter, mem,
  10    ops::Range,
  11    sync::atomic::{AtomicUsize, Ordering::SeqCst},
  12};
  13use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  14
  15pub trait ToFoldPoint {
  16    fn to_fold_point(&self, snapshot: &Snapshot, bias: Bias) -> FoldPoint;
  17}
  18
  19#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  20pub struct FoldPoint(pub super::Point);
  21
  22impl FoldPoint {
  23    pub fn new(row: u32, column: u32) -> Self {
  24        Self(super::Point::new(row, column))
  25    }
  26
  27    pub fn row(self) -> u32 {
  28        self.0.row
  29    }
  30
  31    pub fn column(self) -> u32 {
  32        self.0.column
  33    }
  34
  35    pub fn row_mut(&mut self) -> &mut u32 {
  36        &mut self.0.row
  37    }
  38
  39    #[cfg(test)]
  40    pub fn column_mut(&mut self) -> &mut u32 {
  41        &mut self.0.column
  42    }
  43
  44    pub fn to_buffer_point(&self, snapshot: &Snapshot) -> 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: &Snapshot) -> 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            .to_offset(cursor.start().1 + overshoot)
  58    }
  59
  60    pub fn to_offset(&self, snapshot: &Snapshot) -> 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                .to_offset(cursor.start().1.input.lines + overshoot);
  73            offset += end_buffer_offset - cursor.start().1.input.bytes;
  74        }
  75        FoldOffset(offset)
  76    }
  77}
  78
  79impl ToFoldPoint for Point {
  80    fn to_fold_point(&self, snapshot: &Snapshot, bias: Bias) -> FoldPoint {
  81        let mut cursor = snapshot.transforms.cursor::<(Point, FoldPoint)>();
  82        cursor.seek(self, Bias::Right, &());
  83        if cursor.item().map_or(false, |t| t.is_fold()) {
  84            if bias == Bias::Left || *self == cursor.start().0 {
  85                cursor.start().1
  86            } else {
  87                cursor.end(&()).1
  88            }
  89        } else {
  90            let overshoot = *self - cursor.start().0;
  91            FoldPoint(cmp::min(
  92                cursor.start().1 .0 + overshoot,
  93                cursor.end(&()).1 .0,
  94            ))
  95        }
  96    }
  97}
  98
  99pub struct FoldMapWriter<'a>(&'a mut FoldMap);
 100
 101impl<'a> FoldMapWriter<'a> {
 102    pub fn fold<T: ToOffset>(
 103        &mut self,
 104        ranges: impl IntoIterator<Item = Range<T>>,
 105        cx: &AppContext,
 106    ) -> (Snapshot, Vec<FoldEdit>) {
 107        let mut edits = Vec::new();
 108        let mut folds = Vec::new();
 109        let buffer = self.0.buffer.read(cx).snapshot();
 110        for range in ranges.into_iter() {
 111            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
 112            if range.start != range.end {
 113                let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 114                folds.push(fold);
 115                edits.push(buffer::Edit {
 116                    old: range.clone(),
 117                    new: range,
 118                });
 119            }
 120        }
 121
 122        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 123
 124        self.0.folds = {
 125            let mut new_tree = SumTree::new();
 126            let mut cursor = self.0.folds.cursor::<Fold>();
 127            for fold in folds {
 128                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 129                new_tree.push(fold, &buffer);
 130            }
 131            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 132            new_tree
 133        };
 134
 135        consolidate_buffer_edits(&mut edits);
 136        let edits = self.0.apply_edits(edits, cx);
 137        let snapshot = Snapshot {
 138            transforms: self.0.transforms.lock().clone(),
 139            folds: self.0.folds.clone(),
 140            buffer_snapshot: self.0.buffer.read(cx).snapshot(),
 141            version: self.0.version.load(SeqCst),
 142        };
 143        (snapshot, edits)
 144    }
 145
 146    pub fn unfold<T: ToOffset>(
 147        &mut self,
 148        ranges: impl IntoIterator<Item = Range<T>>,
 149        cx: &AppContext,
 150    ) -> (Snapshot, Vec<FoldEdit>) {
 151        let mut edits = Vec::new();
 152        let mut fold_ixs_to_delete = Vec::new();
 153        let buffer = self.0.buffer.read(cx).snapshot();
 154        for range in ranges.into_iter() {
 155            // Remove intersecting folds and add their ranges to edits that are passed to apply_edits.
 156            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 157            while let Some(fold) = folds_cursor.item() {
 158                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 159                edits.push(buffer::Edit {
 160                    old: offset_range.clone(),
 161                    new: offset_range,
 162                });
 163                fold_ixs_to_delete.push(*folds_cursor.start());
 164                folds_cursor.next(&buffer);
 165            }
 166        }
 167
 168        fold_ixs_to_delete.sort_unstable();
 169        fold_ixs_to_delete.dedup();
 170
 171        self.0.folds = {
 172            let mut cursor = self.0.folds.cursor::<usize>();
 173            let mut folds = SumTree::new();
 174            for fold_ix in fold_ixs_to_delete {
 175                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 176                cursor.next(&buffer);
 177            }
 178            folds.push_tree(cursor.suffix(&buffer), &buffer);
 179            folds
 180        };
 181
 182        consolidate_buffer_edits(&mut edits);
 183        let edits = self.0.apply_edits(edits, cx);
 184        let snapshot = Snapshot {
 185            transforms: self.0.transforms.lock().clone(),
 186            folds: self.0.folds.clone(),
 187            buffer_snapshot: self.0.buffer.read(cx).snapshot(),
 188            version: self.0.version.load(SeqCst),
 189        };
 190        (snapshot, edits)
 191    }
 192}
 193
 194pub struct FoldMap {
 195    buffer: ModelHandle<Buffer>,
 196    transforms: Mutex<SumTree<Transform>>,
 197    folds: SumTree<Fold>,
 198    last_sync: Mutex<SyncState>,
 199    version: AtomicUsize,
 200}
 201
 202#[derive(Clone)]
 203struct SyncState {
 204    version: clock::Global,
 205    parse_count: usize,
 206    diagnostics_update_count: usize,
 207}
 208
 209impl FoldMap {
 210    pub fn new(buffer_handle: ModelHandle<Buffer>, cx: &AppContext) -> (Self, Snapshot) {
 211        let buffer = buffer_handle.read(cx);
 212        let this = Self {
 213            buffer: buffer_handle,
 214            folds: Default::default(),
 215            transforms: Mutex::new(SumTree::from_item(
 216                Transform {
 217                    summary: TransformSummary {
 218                        input: buffer.text_summary(),
 219                        output: buffer.text_summary(),
 220                    },
 221                    output_text: None,
 222                },
 223                &(),
 224            )),
 225            last_sync: Mutex::new(SyncState {
 226                version: buffer.version(),
 227                parse_count: buffer.parse_count(),
 228                diagnostics_update_count: buffer.diagnostics_update_count(),
 229            }),
 230            version: AtomicUsize::new(0),
 231        };
 232        let (snapshot, _) = this.read(cx);
 233        (this, snapshot)
 234    }
 235
 236    pub fn read(&self, cx: &AppContext) -> (Snapshot, Vec<FoldEdit>) {
 237        let edits = self.sync(cx);
 238        self.check_invariants(cx);
 239        let snapshot = Snapshot {
 240            transforms: self.transforms.lock().clone(),
 241            folds: self.folds.clone(),
 242            buffer_snapshot: self.buffer.read(cx).snapshot(),
 243            version: self.version.load(SeqCst),
 244        };
 245        (snapshot, edits)
 246    }
 247
 248    pub fn write(&mut self, cx: &AppContext) -> (FoldMapWriter, Snapshot, Vec<FoldEdit>) {
 249        let (snapshot, edits) = self.read(cx);
 250        (FoldMapWriter(self), snapshot, edits)
 251    }
 252
 253    fn sync(&self, cx: &AppContext) -> Vec<FoldEdit> {
 254        let buffer = self.buffer.read(cx);
 255        let last_sync = mem::replace(
 256            &mut *self.last_sync.lock(),
 257            SyncState {
 258                version: buffer.version(),
 259                parse_count: buffer.parse_count(),
 260                diagnostics_update_count: buffer.diagnostics_update_count(),
 261            },
 262        );
 263        let edits = buffer
 264            .edits_since(&last_sync.version)
 265            .map(Into::into)
 266            .collect::<Vec<_>>();
 267        if edits.is_empty() {
 268            if last_sync.parse_count != buffer.parse_count()
 269                || last_sync.diagnostics_update_count != buffer.diagnostics_update_count()
 270            {
 271                self.version.fetch_add(1, SeqCst);
 272            }
 273            Vec::new()
 274        } else {
 275            self.apply_edits(edits, cx)
 276        }
 277    }
 278
 279    fn check_invariants(&self, cx: &AppContext) {
 280        if cfg!(test) {
 281            let buffer = self.buffer.read(cx);
 282            assert_eq!(
 283                self.transforms.lock().summary().input.bytes,
 284                buffer.len(),
 285                "transform tree does not match buffer's length"
 286            );
 287        }
 288    }
 289
 290    fn apply_edits(
 291        &self,
 292        buffer_edits: Vec<buffer::Edit<usize>>,
 293        cx: &AppContext,
 294    ) -> Vec<FoldEdit> {
 295        let buffer = self.buffer.read(cx).snapshot();
 296        let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 297
 298        let mut new_transforms = SumTree::new();
 299        let mut transforms = self.transforms.lock();
 300        let mut cursor = transforms.cursor::<usize>();
 301        cursor.seek(&0, Bias::Right, &());
 302
 303        while let Some(mut edit) = buffer_edits_iter.next() {
 304            new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 305            edit.new.start -= edit.old.start - cursor.start();
 306            edit.old.start = *cursor.start();
 307
 308            cursor.seek(&edit.old.end, Bias::Right, &());
 309            cursor.next(&());
 310
 311            let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 312            loop {
 313                edit.old.end = *cursor.start();
 314
 315                if let Some(next_edit) = buffer_edits_iter.peek() {
 316                    if next_edit.old.start > edit.old.end {
 317                        break;
 318                    }
 319
 320                    let next_edit = buffer_edits_iter.next().unwrap();
 321                    delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 322
 323                    if next_edit.old.end >= edit.old.end {
 324                        edit.old.end = next_edit.old.end;
 325                        cursor.seek(&edit.old.end, Bias::Right, &());
 326                        cursor.next(&());
 327                    }
 328                } else {
 329                    break;
 330                }
 331            }
 332
 333            edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 334
 335            let anchor = buffer.anchor_before(edit.new.start);
 336            let mut folds_cursor = self.folds.cursor::<Fold>();
 337            folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &buffer);
 338
 339            let mut folds = iter::from_fn({
 340                let buffer = &buffer;
 341                move || {
 342                    let item = folds_cursor
 343                        .item()
 344                        .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 345                    folds_cursor.next(buffer);
 346                    item
 347                }
 348            })
 349            .peekable();
 350
 351            while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 352                let mut fold = folds.next().unwrap();
 353                let sum = new_transforms.summary();
 354
 355                assert!(fold.start >= sum.input.bytes);
 356
 357                while folds
 358                    .peek()
 359                    .map_or(false, |next_fold| next_fold.start <= fold.end)
 360                {
 361                    let next_fold = folds.next().unwrap();
 362                    if next_fold.end > fold.end {
 363                        fold.end = next_fold.end;
 364                    }
 365                }
 366
 367                if fold.start > sum.input.bytes {
 368                    let text_summary = buffer.text_summary_for_range(sum.input.bytes..fold.start);
 369                    new_transforms.push(
 370                        Transform {
 371                            summary: TransformSummary {
 372                                output: text_summary.clone(),
 373                                input: text_summary,
 374                            },
 375                            output_text: None,
 376                        },
 377                        &(),
 378                    );
 379                }
 380
 381                if fold.end > fold.start {
 382                    let output_text = "";
 383                    let chars = output_text.chars().count() as u32;
 384                    let lines = Point::new(0, output_text.len() as u32);
 385                    let lines_utf16 = PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 386                    new_transforms.push(
 387                        Transform {
 388                            summary: TransformSummary {
 389                                output: TextSummary {
 390                                    bytes: output_text.len(),
 391                                    lines,
 392                                    lines_utf16,
 393                                    first_line_chars: chars,
 394                                    last_line_chars: chars,
 395                                    longest_row: 0,
 396                                    longest_row_chars: chars,
 397                                },
 398                                input: buffer.text_summary_for_range(fold.start..fold.end),
 399                            },
 400                            output_text: Some(output_text),
 401                        },
 402                        &(),
 403                    );
 404                }
 405            }
 406
 407            let sum = new_transforms.summary();
 408            if sum.input.bytes < edit.new.end {
 409                let text_summary = buffer.text_summary_for_range(sum.input.bytes..edit.new.end);
 410                new_transforms.push(
 411                    Transform {
 412                        summary: TransformSummary {
 413                            output: text_summary.clone(),
 414                            input: text_summary,
 415                        },
 416                        output_text: None,
 417                    },
 418                    &(),
 419                );
 420            }
 421        }
 422
 423        new_transforms.push_tree(cursor.suffix(&()), &());
 424        if new_transforms.is_empty() {
 425            let text_summary = buffer.text_summary();
 426            new_transforms.push(
 427                Transform {
 428                    summary: TransformSummary {
 429                        output: text_summary.clone(),
 430                        input: text_summary,
 431                    },
 432                    output_text: None,
 433                },
 434                &(),
 435            );
 436        }
 437
 438        drop(cursor);
 439
 440        let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 441        {
 442            let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 443            let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 444
 445            for mut edit in buffer_edits {
 446                old_transforms.seek(&edit.old.start, Bias::Left, &());
 447                if old_transforms.item().map_or(false, |t| t.is_fold()) {
 448                    edit.old.start = old_transforms.start().0;
 449                }
 450                let old_start =
 451                    old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 452
 453                old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 454                if old_transforms.item().map_or(false, |t| t.is_fold()) {
 455                    old_transforms.next(&());
 456                    edit.old.end = old_transforms.start().0;
 457                }
 458                let old_end =
 459                    old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 460
 461                new_transforms.seek(&edit.new.start, Bias::Left, &());
 462                if new_transforms.item().map_or(false, |t| t.is_fold()) {
 463                    edit.new.start = new_transforms.start().0;
 464                }
 465                let new_start =
 466                    new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 467
 468                new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 469                if new_transforms.item().map_or(false, |t| t.is_fold()) {
 470                    new_transforms.next(&());
 471                    edit.new.end = new_transforms.start().0;
 472                }
 473                let new_end =
 474                    new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 475
 476                fold_edits.push(FoldEdit {
 477                    old_bytes: FoldOffset(old_start)..FoldOffset(old_end),
 478                    new_bytes: FoldOffset(new_start)..FoldOffset(new_end),
 479                });
 480            }
 481
 482            consolidate_fold_edits(&mut fold_edits);
 483        }
 484
 485        *transforms = new_transforms;
 486        self.version.fetch_add(1, SeqCst);
 487        fold_edits
 488    }
 489}
 490
 491#[derive(Clone)]
 492pub struct Snapshot {
 493    transforms: SumTree<Transform>,
 494    folds: SumTree<Fold>,
 495    buffer_snapshot: language::Snapshot,
 496    pub version: usize,
 497}
 498
 499impl Snapshot {
 500    #[cfg(test)]
 501    pub fn text(&self) -> String {
 502        self.chunks_at(FoldOffset(0)).collect()
 503    }
 504
 505    #[cfg(test)]
 506    pub fn fold_count(&self) -> usize {
 507        self.folds.items(&self.buffer_snapshot).len()
 508    }
 509
 510    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 511        let mut summary = TextSummary::default();
 512
 513        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 514        cursor.seek(&range.start, Bias::Right, &());
 515        if let Some(transform) = cursor.item() {
 516            let start_in_transform = range.start.0 - cursor.start().0 .0;
 517            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 518            if let Some(output_text) = transform.output_text {
 519                summary = TextSummary::from(
 520                    &output_text
 521                        [start_in_transform.column as usize..end_in_transform.column as usize],
 522                );
 523            } else {
 524                let buffer_start = cursor.start().1 + start_in_transform;
 525                let buffer_end = cursor.start().1 + end_in_transform;
 526                summary = self
 527                    .buffer_snapshot
 528                    .text_summary_for_range(buffer_start..buffer_end);
 529            }
 530        }
 531
 532        if range.end > cursor.end(&()).0 {
 533            cursor.next(&());
 534            summary += &cursor
 535                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 536                .output;
 537            if let Some(transform) = cursor.item() {
 538                let end_in_transform = range.end.0 - cursor.start().0 .0;
 539                if let Some(output_text) = transform.output_text {
 540                    summary += TextSummary::from(&output_text[..end_in_transform.column as usize]);
 541                } else {
 542                    let buffer_start = cursor.start().1;
 543                    let buffer_end = cursor.start().1 + end_in_transform;
 544                    summary += self
 545                        .buffer_snapshot
 546                        .text_summary_for_range(buffer_start..buffer_end);
 547                }
 548            }
 549        }
 550
 551        summary
 552    }
 553
 554    #[cfg(test)]
 555    pub fn len(&self) -> FoldOffset {
 556        FoldOffset(self.transforms.summary().output.bytes)
 557    }
 558
 559    #[cfg(test)]
 560    pub fn line_len(&self, row: u32) -> u32 {
 561        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 562        let line_end = if row >= self.max_point().row() {
 563            self.len().0
 564        } else {
 565            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 566        };
 567        (line_end - line_start) as u32
 568    }
 569
 570    pub fn buffer_rows(&self, start_row: u32) -> BufferRows {
 571        if start_row > self.transforms.summary().output.lines.row {
 572            panic!("invalid display row {}", start_row);
 573        }
 574
 575        let fold_point = FoldPoint::new(start_row, 0);
 576        let mut cursor = self.transforms.cursor();
 577        cursor.seek(&fold_point, Bias::Left, &());
 578        BufferRows { fold_point, cursor }
 579    }
 580
 581    pub fn max_point(&self) -> FoldPoint {
 582        FoldPoint(self.transforms.summary().output.lines)
 583    }
 584
 585    #[cfg(test)]
 586    pub fn longest_row(&self) -> u32 {
 587        self.transforms.summary().output.longest_row
 588    }
 589
 590    pub fn folds_in_range<'a, T>(
 591        &'a self,
 592        range: Range<T>,
 593    ) -> impl Iterator<Item = &'a Range<Anchor>>
 594    where
 595        T: ToOffset,
 596    {
 597        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 598        iter::from_fn(move || {
 599            let item = folds.item().map(|f| &f.0);
 600            folds.next(&self.buffer_snapshot);
 601            item
 602        })
 603    }
 604
 605    pub fn intersects_fold<T>(&self, offset: T) -> bool
 606    where
 607        T: ToOffset,
 608    {
 609        let offset = offset.to_offset(&self.buffer_snapshot);
 610        let mut cursor = self.transforms.cursor::<usize>();
 611        cursor.seek(&offset, Bias::Right, &());
 612        cursor.item().map_or(false, |t| t.output_text.is_some())
 613    }
 614
 615    pub fn is_line_folded(&self, output_row: u32) -> bool {
 616        let mut cursor = self.transforms.cursor::<FoldPoint>();
 617        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 618        while let Some(transform) = cursor.item() {
 619            if transform.output_text.is_some() {
 620                return true;
 621            }
 622            if cursor.end(&()).row() == output_row {
 623                cursor.next(&())
 624            } else {
 625                break;
 626            }
 627        }
 628        false
 629    }
 630
 631    pub fn chunks_at(&self, offset: FoldOffset) -> Chunks {
 632        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 633        transform_cursor.seek(&offset, Bias::Right, &());
 634        let overshoot = offset.0 - transform_cursor.start().0 .0;
 635        let buffer_offset = transform_cursor.start().1 + overshoot;
 636        Chunks {
 637            transform_cursor,
 638            buffer_offset,
 639            buffer_chunks: self
 640                .buffer_snapshot
 641                .text_for_range(buffer_offset..self.buffer_snapshot.len()),
 642        }
 643    }
 644
 645    pub fn highlighted_chunks(&mut self, range: Range<FoldOffset>) -> HighlightedChunks {
 646        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 647
 648        transform_cursor.seek(&range.end, Bias::Right, &());
 649        let overshoot = range.end.0 - transform_cursor.start().0 .0;
 650        let buffer_end = transform_cursor.start().1 + overshoot;
 651
 652        transform_cursor.seek(&range.start, Bias::Right, &());
 653        let overshoot = range.start.0 - transform_cursor.start().0 .0;
 654        let buffer_start = transform_cursor.start().1 + overshoot;
 655
 656        HighlightedChunks {
 657            transform_cursor,
 658            buffer_offset: buffer_start,
 659            buffer_chunks: self
 660                .buffer_snapshot
 661                .highlighted_text_for_range(buffer_start..buffer_end),
 662            buffer_chunk: None,
 663        }
 664    }
 665
 666    pub fn chars_at<'a>(&'a self, point: FoldPoint) -> impl Iterator<Item = char> + 'a {
 667        let offset = point.to_offset(self);
 668        self.chunks_at(offset).flat_map(str::chars)
 669    }
 670
 671    #[cfg(test)]
 672    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 673        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 674        cursor.seek(&offset, Bias::Right, &());
 675        if let Some(transform) = cursor.item() {
 676            let transform_start = cursor.start().0 .0;
 677            if transform.output_text.is_some() {
 678                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 679                    FoldOffset(transform_start)
 680                } else {
 681                    FoldOffset(cursor.end(&()).0 .0)
 682                }
 683            } else {
 684                let overshoot = offset.0 - transform_start;
 685                let buffer_offset = cursor.start().1 + overshoot;
 686                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 687                FoldOffset(
 688                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 689                        as usize,
 690                )
 691            }
 692        } else {
 693            FoldOffset(self.transforms.summary().output.bytes)
 694        }
 695    }
 696
 697    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 698        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 699        cursor.seek(&point, Bias::Right, &());
 700        if let Some(transform) = cursor.item() {
 701            let transform_start = cursor.start().0 .0;
 702            if transform.output_text.is_some() {
 703                if point.0 == transform_start || matches!(bias, Bias::Left) {
 704                    FoldPoint(transform_start)
 705                } else {
 706                    FoldPoint(cursor.end(&()).0 .0)
 707                }
 708            } else {
 709                let overshoot = point.0 - transform_start;
 710                let buffer_position = cursor.start().1 + overshoot;
 711                let clipped_buffer_position =
 712                    self.buffer_snapshot.clip_point(buffer_position, bias);
 713                FoldPoint::new(
 714                    point.row(),
 715                    ((point.column() as i32) + clipped_buffer_position.column as i32
 716                        - buffer_position.column as i32) as u32,
 717                )
 718            }
 719        } else {
 720            FoldPoint(self.transforms.summary().output.lines)
 721        }
 722    }
 723}
 724
 725fn intersecting_folds<'a, T>(
 726    buffer: &'a buffer::Snapshot,
 727    folds: &'a SumTree<Fold>,
 728    range: Range<T>,
 729    inclusive: bool,
 730) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 731where
 732    T: ToOffset,
 733{
 734    let start = buffer.anchor_before(range.start.to_offset(buffer));
 735    let end = buffer.anchor_after(range.end.to_offset(buffer));
 736    folds.filter::<_, usize>(
 737        move |summary| {
 738            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 739            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 740
 741            if inclusive {
 742                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 743            } else {
 744                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 745            }
 746        },
 747        buffer,
 748    )
 749}
 750
 751fn consolidate_buffer_edits(edits: &mut Vec<buffer::Edit<usize>>) {
 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
 774fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 775    edits.sort_unstable_by(|a, b| {
 776        a.old_bytes
 777            .start
 778            .cmp(&b.old_bytes.start)
 779            .then_with(|| b.old_bytes.end.cmp(&a.old_bytes.end))
 780    });
 781
 782    let mut i = 1;
 783    while i < edits.len() {
 784        let edit = edits[i].clone();
 785        let prev_edit = &mut edits[i - 1];
 786        if prev_edit.old_bytes.end >= edit.old_bytes.start {
 787            prev_edit.old_bytes.end = prev_edit.old_bytes.end.max(edit.old_bytes.end);
 788            prev_edit.new_bytes.start = prev_edit.new_bytes.start.min(edit.new_bytes.start);
 789            prev_edit.new_bytes.end = prev_edit.new_bytes.end.max(edit.new_bytes.end);
 790            edits.remove(i);
 791            continue;
 792        }
 793        i += 1;
 794    }
 795}
 796
 797#[derive(Clone, Debug, Default, Eq, PartialEq)]
 798struct Transform {
 799    summary: TransformSummary,
 800    output_text: Option<&'static str>,
 801}
 802
 803impl Transform {
 804    fn is_fold(&self) -> bool {
 805        self.output_text.is_some()
 806    }
 807}
 808
 809#[derive(Clone, Debug, Default, Eq, PartialEq)]
 810struct TransformSummary {
 811    output: TextSummary,
 812    input: TextSummary,
 813}
 814
 815impl sum_tree::Item for Transform {
 816    type Summary = TransformSummary;
 817
 818    fn summary(&self) -> Self::Summary {
 819        self.summary.clone()
 820    }
 821}
 822
 823impl sum_tree::Summary for TransformSummary {
 824    type Context = ();
 825
 826    fn add_summary(&mut self, other: &Self, _: &()) {
 827        self.input += &other.input;
 828        self.output += &other.output;
 829    }
 830}
 831
 832#[derive(Clone, Debug)]
 833struct Fold(Range<Anchor>);
 834
 835impl Default for Fold {
 836    fn default() -> Self {
 837        Self(Anchor::min()..Anchor::max())
 838    }
 839}
 840
 841impl sum_tree::Item for Fold {
 842    type Summary = FoldSummary;
 843
 844    fn summary(&self) -> Self::Summary {
 845        FoldSummary {
 846            start: self.0.start.clone(),
 847            end: self.0.end.clone(),
 848            min_start: self.0.start.clone(),
 849            max_end: self.0.end.clone(),
 850            count: 1,
 851        }
 852    }
 853}
 854
 855#[derive(Clone, Debug)]
 856struct FoldSummary {
 857    start: Anchor,
 858    end: Anchor,
 859    min_start: Anchor,
 860    max_end: Anchor,
 861    count: usize,
 862}
 863
 864impl Default for FoldSummary {
 865    fn default() -> Self {
 866        Self {
 867            start: Anchor::min(),
 868            end: Anchor::max(),
 869            min_start: Anchor::max(),
 870            max_end: Anchor::min(),
 871            count: 0,
 872        }
 873    }
 874}
 875
 876impl sum_tree::Summary for FoldSummary {
 877    type Context = buffer::Snapshot;
 878
 879    fn add_summary(&mut self, other: &Self, buffer: &buffer::Snapshot) {
 880        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 881            self.min_start = other.min_start.clone();
 882        }
 883        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 884            self.max_end = other.max_end.clone();
 885        }
 886
 887        #[cfg(debug_assertions)]
 888        {
 889            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 890            assert!(start_comparison <= Ordering::Equal);
 891            if start_comparison == Ordering::Equal {
 892                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 893            }
 894        }
 895
 896        self.start = other.start.clone();
 897        self.end = other.end.clone();
 898        self.count += other.count;
 899    }
 900}
 901
 902impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 903    fn add_summary(&mut self, summary: &'a FoldSummary, _: &buffer::Snapshot) {
 904        self.0.start = summary.start.clone();
 905        self.0.end = summary.end.clone();
 906    }
 907}
 908
 909impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 910    fn cmp(&self, other: &Self, buffer: &buffer::Snapshot) -> Ordering {
 911        self.0.cmp(&other.0, buffer).unwrap()
 912    }
 913}
 914
 915impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 916    fn add_summary(&mut self, summary: &'a FoldSummary, _: &buffer::Snapshot) {
 917        *self += summary.count;
 918    }
 919}
 920
 921pub struct BufferRows<'a> {
 922    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 923    fold_point: FoldPoint,
 924}
 925
 926impl<'a> Iterator for BufferRows<'a> {
 927    type Item = u32;
 928
 929    fn next(&mut self) -> Option<Self::Item> {
 930        while self.fold_point > self.cursor.end(&()).0 {
 931            self.cursor.next(&());
 932            if self.cursor.item().is_none() {
 933                // TODO: Return a bool from next?
 934                break;
 935            }
 936        }
 937
 938        if self.cursor.item().is_some() {
 939            let overshoot = self.fold_point.0 - self.cursor.start().0 .0;
 940            let buffer_point = self.cursor.start().1 + overshoot;
 941            *self.fold_point.row_mut() += 1;
 942            Some(buffer_point.row)
 943        } else {
 944            None
 945        }
 946    }
 947}
 948
 949pub struct Chunks<'a> {
 950    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 951    buffer_chunks: buffer::Chunks<'a>,
 952    buffer_offset: usize,
 953}
 954
 955impl<'a> Iterator for Chunks<'a> {
 956    type Item = &'a str;
 957
 958    fn next(&mut self) -> Option<Self::Item> {
 959        let transform = if let Some(item) = self.transform_cursor.item() {
 960            item
 961        } else {
 962            return None;
 963        };
 964
 965        // If we're in a fold, then return the fold's display text and
 966        // advance the transform and buffer cursors to the end of the fold.
 967        if let Some(output_text) = transform.output_text {
 968            self.buffer_offset += transform.summary.input.bytes;
 969            self.buffer_chunks.seek(self.buffer_offset);
 970
 971            while self.buffer_offset >= self.transform_cursor.end(&()).1
 972                && self.transform_cursor.item().is_some()
 973            {
 974                self.transform_cursor.next(&());
 975            }
 976
 977            return Some(output_text);
 978        }
 979
 980        // Otherwise, take a chunk from the buffer's text.
 981        if let Some(mut chunk) = self.buffer_chunks.peek() {
 982            let offset_in_chunk = self.buffer_offset - self.buffer_chunks.offset();
 983            chunk = &chunk[offset_in_chunk..];
 984
 985            // Truncate the chunk so that it ends at the next fold.
 986            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 987            if chunk.len() >= region_end {
 988                chunk = &chunk[0..region_end];
 989                self.transform_cursor.next(&());
 990            } else {
 991                self.buffer_chunks.next();
 992            }
 993
 994            self.buffer_offset += chunk.len();
 995            return Some(chunk);
 996        }
 997
 998        None
 999    }
1000}
1001
1002pub struct HighlightedChunks<'a> {
1003    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
1004    buffer_chunks: language::HighlightedChunks<'a>,
1005    buffer_chunk: Option<(usize, HighlightedChunk<'a>)>,
1006    buffer_offset: usize,
1007}
1008
1009impl<'a> Iterator for HighlightedChunks<'a> {
1010    type Item = HighlightedChunk<'a>;
1011
1012    fn next(&mut self) -> Option<Self::Item> {
1013        let transform = if let Some(item) = self.transform_cursor.item() {
1014            item
1015        } else {
1016            return None;
1017        };
1018
1019        // If we're in a fold, then return the fold's display text and
1020        // advance the transform and buffer cursors to the end of the fold.
1021        if let Some(output_text) = transform.output_text {
1022            self.buffer_chunk.take();
1023            self.buffer_offset += transform.summary.input.bytes;
1024            self.buffer_chunks.seek(self.buffer_offset);
1025
1026            while self.buffer_offset >= self.transform_cursor.end(&()).1
1027                && self.transform_cursor.item().is_some()
1028            {
1029                self.transform_cursor.next(&());
1030            }
1031
1032            return Some(HighlightedChunk {
1033                text: output_text,
1034                highlight_id: HighlightId::default(),
1035                diagnostic: None,
1036            });
1037        }
1038
1039        // Retrieve a chunk from the current location in the buffer.
1040        if self.buffer_chunk.is_none() {
1041            let chunk_offset = self.buffer_chunks.offset();
1042            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
1043        }
1044
1045        // Otherwise, take a chunk from the buffer's text.
1046        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
1047            let offset_in_chunk = self.buffer_offset - chunk_offset;
1048            chunk.text = &chunk.text[offset_in_chunk..];
1049
1050            // Truncate the chunk so that it ends at the next fold.
1051            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
1052            if chunk.text.len() >= region_end {
1053                chunk.text = &chunk.text[0..region_end];
1054                self.transform_cursor.next(&());
1055            } else {
1056                self.buffer_chunk.take();
1057            }
1058
1059            self.buffer_offset += chunk.text.len();
1060            return Some(chunk);
1061        }
1062
1063        None
1064    }
1065}
1066
1067impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1068    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1069        self.0 += &summary.output.lines;
1070    }
1071}
1072
1073#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1074pub struct FoldOffset(pub usize);
1075
1076impl FoldOffset {
1077    pub fn to_point(&self, snapshot: &Snapshot) -> FoldPoint {
1078        let mut cursor = snapshot
1079            .transforms
1080            .cursor::<(FoldOffset, TransformSummary)>();
1081        cursor.seek(self, Bias::Right, &());
1082        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1083            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1084        } else {
1085            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1086            let buffer_point = snapshot.buffer_snapshot.to_point(buffer_offset);
1087            buffer_point - cursor.start().1.input.lines
1088        };
1089        FoldPoint(cursor.start().1.output.lines + overshoot)
1090    }
1091}
1092
1093impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1094    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1095        self.0 += &summary.output.bytes;
1096    }
1097}
1098
1099impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1100    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1101        *self += &summary.input.lines;
1102    }
1103}
1104
1105impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1106    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1107        *self += &summary.input.bytes;
1108    }
1109}
1110
1111#[derive(Clone, Debug, PartialEq, Eq)]
1112pub struct FoldEdit {
1113    pub old_bytes: Range<FoldOffset>,
1114    pub new_bytes: Range<FoldOffset>,
1115}
1116
1117#[cfg(test)]
1118impl FoldEdit {
1119    pub fn delta(&self) -> isize {
1120        self.inserted_bytes() as isize - self.deleted_bytes() as isize
1121    }
1122
1123    pub fn deleted_bytes(&self) -> usize {
1124        self.old_bytes.end.0 - self.old_bytes.start.0
1125    }
1126
1127    pub fn inserted_bytes(&self) -> usize {
1128        self.new_bytes.end.0 - self.new_bytes.start.0
1129    }
1130}
1131
1132#[cfg(test)]
1133mod tests {
1134    use super::*;
1135    use crate::{test::sample_text, ToPoint};
1136    use buffer::RandomCharIter;
1137    use rand::prelude::*;
1138    use std::{env, mem};
1139    use Bias::{Left, Right};
1140
1141    #[gpui::test]
1142    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1143        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1144        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1145
1146        let (mut writer, _, _) = map.write(cx.as_ref());
1147        let (snapshot2, edits) = writer.fold(
1148            vec![
1149                Point::new(0, 2)..Point::new(2, 2),
1150                Point::new(2, 4)..Point::new(4, 1),
1151            ],
1152            cx.as_ref(),
1153        );
1154        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1155        assert_eq!(
1156            edits,
1157            &[
1158                FoldEdit {
1159                    old_bytes: FoldOffset(2)..FoldOffset(16),
1160                    new_bytes: FoldOffset(2)..FoldOffset(5),
1161                },
1162                FoldEdit {
1163                    old_bytes: FoldOffset(18)..FoldOffset(29),
1164                    new_bytes: FoldOffset(7)..FoldOffset(10)
1165                },
1166            ]
1167        );
1168
1169        buffer.update(cx, |buffer, cx| {
1170            buffer.edit(
1171                vec![
1172                    Point::new(0, 0)..Point::new(0, 1),
1173                    Point::new(2, 3)..Point::new(2, 3),
1174                ],
1175                "123",
1176                cx,
1177            );
1178        });
1179        let (snapshot3, edits) = map.read(cx.as_ref());
1180        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1181        assert_eq!(
1182            edits,
1183            &[
1184                FoldEdit {
1185                    old_bytes: FoldOffset(0)..FoldOffset(1),
1186                    new_bytes: FoldOffset(0)..FoldOffset(3),
1187                },
1188                FoldEdit {
1189                    old_bytes: FoldOffset(6)..FoldOffset(6),
1190                    new_bytes: FoldOffset(8)..FoldOffset(11),
1191                },
1192            ]
1193        );
1194
1195        buffer.update(cx, |buffer, cx| {
1196            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx)
1197        });
1198        let (snapshot4, _) = map.read(cx.as_ref());
1199        assert_eq!(snapshot4.text(), "123a…c123456eee");
1200
1201        let (mut writer, _, _) = map.write(cx.as_ref());
1202        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)), cx.as_ref());
1203        let (snapshot5, _) = map.read(cx.as_ref());
1204        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1205    }
1206
1207    #[gpui::test]
1208    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1209        let buffer = cx.add_model(|cx| Buffer::new(0, "abcdefghijkl", cx));
1210
1211        {
1212            let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1213
1214            let (mut writer, _, _) = map.write(cx.as_ref());
1215            writer.fold(vec![5..8], cx.as_ref());
1216            let (snapshot, _) = map.read(cx.as_ref());
1217            assert_eq!(snapshot.text(), "abcde…ijkl");
1218
1219            // Create an fold adjacent to the start of the first fold.
1220            let (mut writer, _, _) = map.write(cx.as_ref());
1221            writer.fold(vec![0..1, 2..5], cx.as_ref());
1222            let (snapshot, _) = map.read(cx.as_ref());
1223            assert_eq!(snapshot.text(), "…b…ijkl");
1224
1225            // Create an fold adjacent to the end of the first fold.
1226            let (mut writer, _, _) = map.write(cx.as_ref());
1227            writer.fold(vec![11..11, 8..10], cx.as_ref());
1228            let (snapshot, _) = map.read(cx.as_ref());
1229            assert_eq!(snapshot.text(), "…b…kl");
1230        }
1231
1232        {
1233            let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1234
1235            // Create two adjacent folds.
1236            let (mut writer, _, _) = map.write(cx.as_ref());
1237            writer.fold(vec![0..2, 2..5], cx.as_ref());
1238            let (snapshot, _) = map.read(cx.as_ref());
1239            assert_eq!(snapshot.text(), "…fghijkl");
1240
1241            // Edit within one of the folds.
1242            buffer.update(cx, |buffer, cx| buffer.edit(vec![0..1], "12345", cx));
1243            let (snapshot, _) = map.read(cx.as_ref());
1244            assert_eq!(snapshot.text(), "12345…fghijkl");
1245        }
1246    }
1247
1248    #[gpui::test]
1249    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1250        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1251        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1252        let (mut writer, _, _) = map.write(cx.as_ref());
1253        writer.fold(
1254            vec![
1255                Point::new(0, 2)..Point::new(2, 2),
1256                Point::new(0, 4)..Point::new(1, 0),
1257                Point::new(1, 2)..Point::new(3, 2),
1258                Point::new(3, 1)..Point::new(4, 1),
1259            ],
1260            cx.as_ref(),
1261        );
1262        let (snapshot, _) = map.read(cx.as_ref());
1263        assert_eq!(snapshot.text(), "aa…eeeee");
1264    }
1265
1266    #[gpui::test]
1267    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1268        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1269        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1270
1271        let (mut writer, _, _) = map.write(cx.as_ref());
1272        writer.fold(
1273            vec![
1274                Point::new(0, 2)..Point::new(2, 2),
1275                Point::new(3, 1)..Point::new(4, 1),
1276            ],
1277            cx.as_ref(),
1278        );
1279        let (snapshot, _) = map.read(cx.as_ref());
1280        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1281
1282        buffer.update(cx, |buffer, cx| {
1283            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx)
1284        });
1285        let (snapshot, _) = map.read(cx.as_ref());
1286        assert_eq!(snapshot.text(), "aa…eeeee");
1287    }
1288
1289    #[gpui::test]
1290    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1291        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1292        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1293        let buffer = buffer.read(cx);
1294
1295        let (mut writer, _, _) = map.write(cx.as_ref());
1296        writer.fold(
1297            vec![
1298                Point::new(0, 2)..Point::new(2, 2),
1299                Point::new(0, 4)..Point::new(1, 0),
1300                Point::new(1, 2)..Point::new(3, 2),
1301                Point::new(3, 1)..Point::new(4, 1),
1302            ],
1303            cx.as_ref(),
1304        );
1305        let (snapshot, _) = map.read(cx.as_ref());
1306        let fold_ranges = snapshot
1307            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1308            .map(|fold| fold.start.to_point(buffer)..fold.end.to_point(buffer))
1309            .collect::<Vec<_>>();
1310        assert_eq!(
1311            fold_ranges,
1312            vec![
1313                Point::new(0, 2)..Point::new(2, 2),
1314                Point::new(1, 2)..Point::new(3, 2)
1315            ]
1316        );
1317    }
1318
1319    #[gpui::test(iterations = 100)]
1320    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1321        let operations = env::var("OPERATIONS")
1322            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1323            .unwrap_or(10);
1324
1325        let buffer = cx.add_model(|cx| {
1326            let len = rng.gen_range(0..10);
1327            let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1328            Buffer::new(0, text, cx)
1329        });
1330        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1331
1332        let (mut initial_snapshot, _) = map.read(cx.as_ref());
1333        let mut snapshot_edits = Vec::new();
1334
1335        for _ in 0..operations {
1336            log::info!("text: {:?}", buffer.read(cx).text());
1337            match rng.gen_range(0..=100) {
1338                0..=59 => {
1339                    snapshot_edits.extend(map.randomly_mutate(&mut rng, cx.as_ref()));
1340                }
1341                _ => {
1342                    let edits = buffer.update(cx, |buffer, _| {
1343                        let start_version = buffer.version.clone();
1344                        let edit_count = rng.gen_range(1..=5);
1345                        buffer.randomly_edit(&mut rng, edit_count);
1346                        buffer
1347                            .edits_since::<Point>(&start_version)
1348                            .collect::<Vec<_>>()
1349                    });
1350                    log::info!("editing {:?}", edits);
1351                }
1352            }
1353
1354            let buffer = map.buffer.read(cx).snapshot();
1355            let mut expected_text: String = buffer.text().into();
1356            let mut expected_buffer_rows = Vec::new();
1357            let mut next_row = buffer.max_point().row;
1358            for fold_range in map.merged_fold_ranges(cx.as_ref()).into_iter().rev() {
1359                let fold_start = buffer.point_for_offset(fold_range.start).unwrap();
1360                let fold_end = buffer.point_for_offset(fold_range.end).unwrap();
1361                expected_buffer_rows.extend((fold_end.row + 1..=next_row).rev());
1362                next_row = fold_start.row;
1363
1364                expected_text.replace_range(fold_range.start..fold_range.end, "");
1365            }
1366            expected_buffer_rows.extend((0..=next_row).rev());
1367            expected_buffer_rows.reverse();
1368
1369            let (snapshot, edits) = map.read(cx.as_ref());
1370            assert_eq!(snapshot.text(), expected_text);
1371            snapshot_edits.push((snapshot.clone(), edits));
1372
1373            for (output_row, line) in expected_text.lines().enumerate() {
1374                let line_len = snapshot.line_len(output_row as u32);
1375                assert_eq!(line_len, line.len() as u32);
1376            }
1377
1378            let longest_row = snapshot.longest_row();
1379            let longest_char_column = expected_text
1380                .split('\n')
1381                .nth(longest_row as usize)
1382                .unwrap()
1383                .chars()
1384                .count();
1385            let mut fold_point = FoldPoint::new(0, 0);
1386            let mut fold_offset = FoldOffset(0);
1387            let mut char_column = 0;
1388            for c in expected_text.chars() {
1389                let buffer_point = fold_point.to_buffer_point(&snapshot);
1390                let buffer_offset = buffer_point.to_offset(&buffer);
1391                assert_eq!(
1392                    buffer_point.to_fold_point(&snapshot, Right),
1393                    fold_point,
1394                    "{:?} -> fold point",
1395                    buffer_point,
1396                );
1397                assert_eq!(
1398                    fold_point.to_buffer_offset(&snapshot),
1399                    buffer_offset,
1400                    "fold_point.to_buffer_offset({:?})",
1401                    fold_point,
1402                );
1403                assert_eq!(
1404                    fold_point.to_offset(&snapshot),
1405                    fold_offset,
1406                    "fold_point.to_offset({:?})",
1407                    fold_point,
1408                );
1409
1410                if c == '\n' {
1411                    *fold_point.row_mut() += 1;
1412                    *fold_point.column_mut() = 0;
1413                    char_column = 0;
1414                } else {
1415                    *fold_point.column_mut() += c.len_utf8() as u32;
1416                    char_column += 1;
1417                }
1418                fold_offset.0 += c.len_utf8();
1419                if char_column > longest_char_column {
1420                    panic!(
1421                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1422                        longest_row,
1423                        longest_char_column,
1424                        fold_point.row(),
1425                        char_column
1426                    );
1427                }
1428            }
1429
1430            for _ in 0..5 {
1431                let offset = snapshot
1432                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1433                assert_eq!(
1434                    snapshot.chunks_at(offset).collect::<String>(),
1435                    &expected_text[offset.0..],
1436                );
1437            }
1438
1439            for (idx, buffer_row) in expected_buffer_rows.iter().enumerate() {
1440                let fold_row = Point::new(*buffer_row, 0)
1441                    .to_fold_point(&snapshot, Right)
1442                    .row();
1443                assert_eq!(
1444                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1445                    expected_buffer_rows[idx..],
1446                );
1447            }
1448
1449            for fold_range in map.merged_fold_ranges(cx.as_ref()) {
1450                let fold_point = fold_range
1451                    .start
1452                    .to_point(&buffer)
1453                    .to_fold_point(&snapshot, Right);
1454                assert!(snapshot.is_line_folded(fold_point.row()));
1455            }
1456
1457            for _ in 0..5 {
1458                let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1459                let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1460                let expected_folds = map
1461                    .folds
1462                    .items(&buffer)
1463                    .into_iter()
1464                    .filter(|fold| {
1465                        let start = buffer.anchor_before(start);
1466                        let end = buffer.anchor_after(end);
1467                        start.cmp(&fold.0.end, &buffer).unwrap() == Ordering::Less
1468                            && end.cmp(&fold.0.start, &buffer).unwrap() == Ordering::Greater
1469                    })
1470                    .map(|fold| fold.0)
1471                    .collect::<Vec<_>>();
1472
1473                assert_eq!(
1474                    snapshot
1475                        .folds_in_range(start..end)
1476                        .cloned()
1477                        .collect::<Vec<_>>(),
1478                    expected_folds
1479                );
1480            }
1481
1482            let text = snapshot.text();
1483            for _ in 0..5 {
1484                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1485                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1486                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1487                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1488                let mut start =
1489                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1490                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1491                if start > end {
1492                    mem::swap(&mut start, &mut end);
1493                }
1494
1495                let lines = start..end;
1496                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1497                assert_eq!(
1498                    snapshot.text_summary_for_range(lines),
1499                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1500                )
1501            }
1502
1503            let mut text = initial_snapshot.text();
1504            for (snapshot, edits) in snapshot_edits.drain(..) {
1505                let new_text = snapshot.text();
1506                let mut delta = 0isize;
1507                for edit in edits {
1508                    let old_bytes = ((edit.old_bytes.start.0 as isize) + delta) as usize
1509                        ..((edit.old_bytes.end.0 as isize) + delta) as usize;
1510                    let new_bytes = edit.new_bytes.start.0..edit.new_bytes.end.0;
1511                    delta += edit.delta();
1512                    text.replace_range(old_bytes, &new_text[new_bytes]);
1513                }
1514
1515                assert_eq!(text, new_text);
1516                initial_snapshot = snapshot;
1517            }
1518        }
1519    }
1520
1521    #[gpui::test]
1522    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1523        let text = sample_text(6, 6) + "\n";
1524        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
1525
1526        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1527
1528        let (mut writer, _, _) = map.write(cx.as_ref());
1529        writer.fold(
1530            vec![
1531                Point::new(0, 2)..Point::new(2, 2),
1532                Point::new(3, 1)..Point::new(4, 1),
1533            ],
1534            cx.as_ref(),
1535        );
1536
1537        let (snapshot, _) = map.read(cx.as_ref());
1538        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1539        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), [0, 3, 5, 6]);
1540        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [6]);
1541    }
1542
1543    impl FoldMap {
1544        fn merged_fold_ranges(&self, cx: &AppContext) -> Vec<Range<usize>> {
1545            let buffer = self.buffer.read(cx).snapshot();
1546            let mut folds = self.folds.items(&buffer);
1547            // Ensure sorting doesn't change how folds get merged and displayed.
1548            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1549            let mut fold_ranges = folds
1550                .iter()
1551                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1552                .peekable();
1553
1554            let mut merged_ranges = Vec::new();
1555            while let Some(mut fold_range) = fold_ranges.next() {
1556                while let Some(next_range) = fold_ranges.peek() {
1557                    if fold_range.end >= next_range.start {
1558                        if next_range.end > fold_range.end {
1559                            fold_range.end = next_range.end;
1560                        }
1561                        fold_ranges.next();
1562                    } else {
1563                        break;
1564                    }
1565                }
1566                if fold_range.end > fold_range.start {
1567                    merged_ranges.push(fold_range);
1568                }
1569            }
1570            merged_ranges
1571        }
1572
1573        pub fn randomly_mutate(
1574            &mut self,
1575            rng: &mut impl Rng,
1576            cx: &AppContext,
1577        ) -> Vec<(Snapshot, Vec<FoldEdit>)> {
1578            let mut snapshot_edits = Vec::new();
1579            match rng.gen_range(0..=100) {
1580                0..=39 if !self.folds.is_empty() => {
1581                    let buffer = self.buffer.read(cx);
1582                    let mut to_unfold = Vec::new();
1583                    for _ in 0..rng.gen_range(1..=3) {
1584                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1585                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1586                        to_unfold.push(start..end);
1587                    }
1588                    log::info!("unfolding {:?}", to_unfold);
1589                    let (mut writer, snapshot, edits) = self.write(cx.as_ref());
1590                    snapshot_edits.push((snapshot, edits));
1591                    let (snapshot, edits) = writer.fold(to_unfold, cx.as_ref());
1592                    snapshot_edits.push((snapshot, edits));
1593                }
1594                _ => {
1595                    let buffer = self.buffer.read(cx);
1596                    let mut to_fold = Vec::new();
1597                    for _ in 0..rng.gen_range(1..=2) {
1598                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1599                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1600                        to_fold.push(start..end);
1601                    }
1602                    log::info!("folding {:?}", to_fold);
1603                    let (mut writer, snapshot, edits) = self.write(cx.as_ref());
1604                    snapshot_edits.push((snapshot, edits));
1605                    let (snapshot, edits) = writer.fold(to_fold, cx.as_ref());
1606                    snapshot_edits.push((snapshot, edits));
1607                }
1608            }
1609            snapshot_edits
1610        }
1611    }
1612}