1use gpui::{AppContext, ModelHandle};
   2use language::{Anchor, AnchorRangeExt, Buffer, Chunk, Point, PointUtf16, TextSummary, ToOffset};
   3use parking_lot::Mutex;
   4use std::{
   5    cmp::{self, Ordering},
   6    iter, mem,
   7    ops::Range,
   8    sync::atomic::{AtomicUsize, Ordering::SeqCst},
   9};
  10use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  11use theme::SyntaxTheme;
  12
  13pub trait ToFoldPoint {
  14    fn to_fold_point(&self, snapshot: &Snapshot, bias: Bias) -> FoldPoint;
  15}
  16
  17#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  18pub struct FoldPoint(pub super::Point);
  19
  20impl FoldPoint {
  21    pub fn new(row: u32, column: u32) -> Self {
  22        Self(super::Point::new(row, column))
  23    }
  24
  25    pub fn row(self) -> u32 {
  26        self.0.row
  27    }
  28
  29    pub fn column(self) -> u32 {
  30        self.0.column
  31    }
  32
  33    pub fn row_mut(&mut self) -> &mut u32 {
  34        &mut self.0.row
  35    }
  36
  37    #[cfg(test)]
  38    pub fn column_mut(&mut self) -> &mut u32 {
  39        &mut self.0.column
  40    }
  41
  42    pub fn to_buffer_point(&self, snapshot: &Snapshot) -> Point {
  43        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  44        cursor.seek(self, Bias::Right, &());
  45        let overshoot = self.0 - cursor.start().0 .0;
  46        cursor.start().1 + overshoot
  47    }
  48
  49    pub fn to_buffer_offset(&self, snapshot: &Snapshot) -> usize {
  50        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  51        cursor.seek(self, Bias::Right, &());
  52        let overshoot = self.0 - cursor.start().0 .0;
  53        snapshot
  54            .buffer_snapshot
  55            .to_offset(cursor.start().1 + overshoot)
  56    }
  57
  58    pub fn to_offset(&self, snapshot: &Snapshot) -> FoldOffset {
  59        let mut cursor = snapshot
  60            .transforms
  61            .cursor::<(FoldPoint, TransformSummary)>();
  62        cursor.seek(self, Bias::Right, &());
  63        let overshoot = self.0 - cursor.start().1.output.lines;
  64        let mut offset = cursor.start().1.output.bytes;
  65        if !overshoot.is_zero() {
  66            let transform = cursor.item().expect("display point out of range");
  67            assert!(transform.output_text.is_none());
  68            let end_buffer_offset = snapshot
  69                .buffer_snapshot
  70                .to_offset(cursor.start().1.input.lines + overshoot);
  71            offset += end_buffer_offset - cursor.start().1.input.bytes;
  72        }
  73        FoldOffset(offset)
  74    }
  75}
  76
  77impl ToFoldPoint for Point {
  78    fn to_fold_point(&self, snapshot: &Snapshot, bias: Bias) -> FoldPoint {
  79        let mut cursor = snapshot.transforms.cursor::<(Point, FoldPoint)>();
  80        cursor.seek(self, Bias::Right, &());
  81        if cursor.item().map_or(false, |t| t.is_fold()) {
  82            if bias == Bias::Left || *self == cursor.start().0 {
  83                cursor.start().1
  84            } else {
  85                cursor.end(&()).1
  86            }
  87        } else {
  88            let overshoot = *self - cursor.start().0;
  89            FoldPoint(cmp::min(
  90                cursor.start().1 .0 + overshoot,
  91                cursor.end(&()).1 .0,
  92            ))
  93        }
  94    }
  95}
  96
  97pub struct FoldMapWriter<'a>(&'a mut FoldMap);
  98
  99impl<'a> FoldMapWriter<'a> {
 100    pub fn fold<T: ToOffset>(
 101        &mut self,
 102        ranges: impl IntoIterator<Item = Range<T>>,
 103        cx: &AppContext,
 104    ) -> (Snapshot, Vec<FoldEdit>) {
 105        let mut edits = Vec::new();
 106        let mut folds = Vec::new();
 107        let buffer = self.0.buffer.read(cx).snapshot();
 108        for range in ranges.into_iter() {
 109            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
 110            if range.start != range.end {
 111                let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 112                folds.push(fold);
 113                edits.push(text::Edit {
 114                    old: range.clone(),
 115                    new: range,
 116                });
 117            }
 118        }
 119
 120        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 121
 122        self.0.folds = {
 123            let mut new_tree = SumTree::new();
 124            let mut cursor = self.0.folds.cursor::<Fold>();
 125            for fold in folds {
 126                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 127                new_tree.push(fold, &buffer);
 128            }
 129            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 130            new_tree
 131        };
 132
 133        consolidate_buffer_edits(&mut edits);
 134        let edits = self.0.apply_edits(edits, cx);
 135        let snapshot = Snapshot {
 136            transforms: self.0.transforms.lock().clone(),
 137            folds: self.0.folds.clone(),
 138            buffer_snapshot: self.0.buffer.read(cx).snapshot(),
 139            version: self.0.version.load(SeqCst),
 140        };
 141        (snapshot, edits)
 142    }
 143
 144    pub fn unfold<T: ToOffset>(
 145        &mut self,
 146        ranges: impl IntoIterator<Item = Range<T>>,
 147        cx: &AppContext,
 148    ) -> (Snapshot, Vec<FoldEdit>) {
 149        let mut edits = Vec::new();
 150        let mut fold_ixs_to_delete = Vec::new();
 151        let buffer = self.0.buffer.read(cx).snapshot();
 152        for range in ranges.into_iter() {
 153            // Remove intersecting folds and add their ranges to edits that are passed to apply_edits.
 154            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 155            while let Some(fold) = folds_cursor.item() {
 156                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 157                edits.push(text::Edit {
 158                    old: offset_range.clone(),
 159                    new: offset_range,
 160                });
 161                fold_ixs_to_delete.push(*folds_cursor.start());
 162                folds_cursor.next(&buffer);
 163            }
 164        }
 165
 166        fold_ixs_to_delete.sort_unstable();
 167        fold_ixs_to_delete.dedup();
 168
 169        self.0.folds = {
 170            let mut cursor = self.0.folds.cursor::<usize>();
 171            let mut folds = SumTree::new();
 172            for fold_ix in fold_ixs_to_delete {
 173                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 174                cursor.next(&buffer);
 175            }
 176            folds.push_tree(cursor.suffix(&buffer), &buffer);
 177            folds
 178        };
 179
 180        consolidate_buffer_edits(&mut edits);
 181        let edits = self.0.apply_edits(edits, cx);
 182        let snapshot = Snapshot {
 183            transforms: self.0.transforms.lock().clone(),
 184            folds: self.0.folds.clone(),
 185            buffer_snapshot: self.0.buffer.read(cx).snapshot(),
 186            version: self.0.version.load(SeqCst),
 187        };
 188        (snapshot, edits)
 189    }
 190}
 191
 192pub struct FoldMap {
 193    buffer: ModelHandle<Buffer>,
 194    transforms: Mutex<SumTree<Transform>>,
 195    folds: SumTree<Fold>,
 196    last_sync: Mutex<SyncState>,
 197    version: AtomicUsize,
 198}
 199
 200#[derive(Clone)]
 201struct SyncState {
 202    version: clock::Global,
 203    parse_count: usize,
 204    diagnostics_update_count: usize,
 205}
 206
 207impl FoldMap {
 208    pub fn new(buffer_handle: ModelHandle<Buffer>, cx: &AppContext) -> (Self, Snapshot) {
 209        let buffer = buffer_handle.read(cx);
 210        let this = Self {
 211            buffer: buffer_handle,
 212            folds: Default::default(),
 213            transforms: Mutex::new(SumTree::from_item(
 214                Transform {
 215                    summary: TransformSummary {
 216                        input: buffer.text_summary(),
 217                        output: buffer.text_summary(),
 218                    },
 219                    output_text: None,
 220                },
 221                &(),
 222            )),
 223            last_sync: Mutex::new(SyncState {
 224                version: buffer.version(),
 225                parse_count: buffer.parse_count(),
 226                diagnostics_update_count: buffer.diagnostics_update_count(),
 227            }),
 228            version: AtomicUsize::new(0),
 229        };
 230        let (snapshot, _) = this.read(cx);
 231        (this, snapshot)
 232    }
 233
 234    pub fn read(&self, cx: &AppContext) -> (Snapshot, Vec<FoldEdit>) {
 235        let edits = self.sync(cx);
 236        self.check_invariants(cx);
 237        let snapshot = Snapshot {
 238            transforms: self.transforms.lock().clone(),
 239            folds: self.folds.clone(),
 240            buffer_snapshot: self.buffer.read(cx).snapshot(),
 241            version: self.version.load(SeqCst),
 242        };
 243        (snapshot, edits)
 244    }
 245
 246    pub fn write(&mut self, cx: &AppContext) -> (FoldMapWriter, Snapshot, Vec<FoldEdit>) {
 247        let (snapshot, edits) = self.read(cx);
 248        (FoldMapWriter(self), snapshot, edits)
 249    }
 250
 251    fn sync(&self, cx: &AppContext) -> Vec<FoldEdit> {
 252        let buffer = self.buffer.read(cx);
 253        let last_sync = mem::replace(
 254            &mut *self.last_sync.lock(),
 255            SyncState {
 256                version: buffer.version(),
 257                parse_count: buffer.parse_count(),
 258                diagnostics_update_count: buffer.diagnostics_update_count(),
 259            },
 260        );
 261        let edits = buffer
 262            .edits_since(&last_sync.version)
 263            .map(Into::into)
 264            .collect::<Vec<_>>();
 265        if edits.is_empty() {
 266            if last_sync.parse_count != buffer.parse_count()
 267                || last_sync.diagnostics_update_count != buffer.diagnostics_update_count()
 268            {
 269                self.version.fetch_add(1, SeqCst);
 270            }
 271            Vec::new()
 272        } else {
 273            self.apply_edits(edits, cx)
 274        }
 275    }
 276
 277    fn check_invariants(&self, cx: &AppContext) {
 278        if cfg!(test) {
 279            let buffer = self.buffer.read(cx);
 280            assert_eq!(
 281                self.transforms.lock().summary().input.bytes,
 282                buffer.len(),
 283                "transform tree does not match buffer's length"
 284            );
 285        }
 286    }
 287
 288    fn apply_edits(&self, buffer_edits: Vec<text::Edit<usize>>, cx: &AppContext) -> Vec<FoldEdit> {
 289        let buffer = self.buffer.read(cx).snapshot();
 290        let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 291
 292        let mut new_transforms = SumTree::new();
 293        let mut transforms = self.transforms.lock();
 294        let mut cursor = transforms.cursor::<usize>();
 295        cursor.seek(&0, Bias::Right, &());
 296
 297        while let Some(mut edit) = buffer_edits_iter.next() {
 298            new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 299            edit.new.start -= edit.old.start - cursor.start();
 300            edit.old.start = *cursor.start();
 301
 302            cursor.seek(&edit.old.end, Bias::Right, &());
 303            cursor.next(&());
 304
 305            let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 306            loop {
 307                edit.old.end = *cursor.start();
 308
 309                if let Some(next_edit) = buffer_edits_iter.peek() {
 310                    if next_edit.old.start > edit.old.end {
 311                        break;
 312                    }
 313
 314                    let next_edit = buffer_edits_iter.next().unwrap();
 315                    delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 316
 317                    if next_edit.old.end >= edit.old.end {
 318                        edit.old.end = next_edit.old.end;
 319                        cursor.seek(&edit.old.end, Bias::Right, &());
 320                        cursor.next(&());
 321                    }
 322                } else {
 323                    break;
 324                }
 325            }
 326
 327            edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 328
 329            let anchor = buffer.anchor_before(edit.new.start);
 330            let mut folds_cursor = self.folds.cursor::<Fold>();
 331            folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &buffer);
 332
 333            let mut folds = iter::from_fn({
 334                let buffer = &buffer;
 335                move || {
 336                    let item = folds_cursor
 337                        .item()
 338                        .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 339                    folds_cursor.next(buffer);
 340                    item
 341                }
 342            })
 343            .peekable();
 344
 345            while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 346                let mut fold = folds.next().unwrap();
 347                let sum = new_transforms.summary();
 348
 349                assert!(fold.start >= sum.input.bytes);
 350
 351                while folds
 352                    .peek()
 353                    .map_or(false, |next_fold| next_fold.start <= fold.end)
 354                {
 355                    let next_fold = folds.next().unwrap();
 356                    if next_fold.end > fold.end {
 357                        fold.end = next_fold.end;
 358                    }
 359                }
 360
 361                if fold.start > sum.input.bytes {
 362                    let text_summary = buffer
 363                        .text_summary_for_range::<TextSummary, _>(sum.input.bytes..fold.start);
 364                    new_transforms.push(
 365                        Transform {
 366                            summary: TransformSummary {
 367                                output: text_summary.clone(),
 368                                input: text_summary,
 369                            },
 370                            output_text: None,
 371                        },
 372                        &(),
 373                    );
 374                }
 375
 376                if fold.end > fold.start {
 377                    let output_text = "…";
 378                    let chars = output_text.chars().count() as u32;
 379                    let lines = Point::new(0, output_text.len() as u32);
 380                    let lines_utf16 = PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 381                    new_transforms.push(
 382                        Transform {
 383                            summary: TransformSummary {
 384                                output: TextSummary {
 385                                    bytes: output_text.len(),
 386                                    lines,
 387                                    lines_utf16,
 388                                    first_line_chars: chars,
 389                                    last_line_chars: chars,
 390                                    longest_row: 0,
 391                                    longest_row_chars: chars,
 392                                },
 393                                input: buffer.text_summary_for_range(fold.start..fold.end),
 394                            },
 395                            output_text: Some(output_text),
 396                        },
 397                        &(),
 398                    );
 399                }
 400            }
 401
 402            let sum = new_transforms.summary();
 403            if sum.input.bytes < edit.new.end {
 404                let text_summary =
 405                    buffer.text_summary_for_range::<TextSummary, _>(sum.input.bytes..edit.new.end);
 406                new_transforms.push(
 407                    Transform {
 408                        summary: TransformSummary {
 409                            output: text_summary.clone(),
 410                            input: text_summary,
 411                        },
 412                        output_text: None,
 413                    },
 414                    &(),
 415                );
 416            }
 417        }
 418
 419        new_transforms.push_tree(cursor.suffix(&()), &());
 420        if new_transforms.is_empty() {
 421            let text_summary = buffer.text_summary();
 422            new_transforms.push(
 423                Transform {
 424                    summary: TransformSummary {
 425                        output: text_summary.clone(),
 426                        input: text_summary,
 427                    },
 428                    output_text: None,
 429                },
 430                &(),
 431            );
 432        }
 433
 434        drop(cursor);
 435
 436        let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 437        {
 438            let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 439            let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 440
 441            for mut edit in buffer_edits {
 442                old_transforms.seek(&edit.old.start, Bias::Left, &());
 443                if old_transforms.item().map_or(false, |t| t.is_fold()) {
 444                    edit.old.start = old_transforms.start().0;
 445                }
 446                let old_start =
 447                    old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 448
 449                old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 450                if old_transforms.item().map_or(false, |t| t.is_fold()) {
 451                    old_transforms.next(&());
 452                    edit.old.end = old_transforms.start().0;
 453                }
 454                let old_end =
 455                    old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 456
 457                new_transforms.seek(&edit.new.start, Bias::Left, &());
 458                if new_transforms.item().map_or(false, |t| t.is_fold()) {
 459                    edit.new.start = new_transforms.start().0;
 460                }
 461                let new_start =
 462                    new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 463
 464                new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 465                if new_transforms.item().map_or(false, |t| t.is_fold()) {
 466                    new_transforms.next(&());
 467                    edit.new.end = new_transforms.start().0;
 468                }
 469                let new_end =
 470                    new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 471
 472                fold_edits.push(FoldEdit {
 473                    old_bytes: FoldOffset(old_start)..FoldOffset(old_end),
 474                    new_bytes: FoldOffset(new_start)..FoldOffset(new_end),
 475                });
 476            }
 477
 478            consolidate_fold_edits(&mut fold_edits);
 479        }
 480
 481        *transforms = new_transforms;
 482        self.version.fetch_add(1, SeqCst);
 483        fold_edits
 484    }
 485}
 486
 487#[derive(Clone)]
 488pub struct Snapshot {
 489    transforms: SumTree<Transform>,
 490    folds: SumTree<Fold>,
 491    buffer_snapshot: language::Snapshot,
 492    pub version: usize,
 493}
 494
 495impl Snapshot {
 496    #[cfg(test)]
 497    pub fn text(&self) -> String {
 498        self.chunks(FoldOffset(0)..self.len(), 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 len(&self) -> FoldOffset {
 553        FoldOffset(self.transforms.summary().output.bytes)
 554    }
 555
 556    #[cfg(test)]
 557    pub fn line_len(&self, row: u32) -> u32 {
 558        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 559        let line_end = if row >= self.max_point().row() {
 560            self.len().0
 561        } else {
 562            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 563        };
 564        (line_end - line_start) as u32
 565    }
 566
 567    pub fn buffer_rows(&self, start_row: u32) -> BufferRows {
 568        if start_row > self.transforms.summary().output.lines.row {
 569            panic!("invalid display row {}", start_row);
 570        }
 571
 572        let fold_point = FoldPoint::new(start_row, 0);
 573        let mut cursor = self.transforms.cursor();
 574        cursor.seek(&fold_point, Bias::Left, &());
 575        BufferRows { fold_point, cursor }
 576    }
 577
 578    pub fn max_point(&self) -> FoldPoint {
 579        FoldPoint(self.transforms.summary().output.lines)
 580    }
 581
 582    #[cfg(test)]
 583    pub fn longest_row(&self) -> u32 {
 584        self.transforms.summary().output.longest_row
 585    }
 586
 587    pub fn folds_in_range<'a, T>(
 588        &'a self,
 589        range: Range<T>,
 590    ) -> impl Iterator<Item = &'a Range<Anchor>>
 591    where
 592        T: ToOffset,
 593    {
 594        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 595        iter::from_fn(move || {
 596            let item = folds.item().map(|f| &f.0);
 597            folds.next(&self.buffer_snapshot);
 598            item
 599        })
 600    }
 601
 602    pub fn intersects_fold<T>(&self, offset: T) -> bool
 603    where
 604        T: ToOffset,
 605    {
 606        let offset = offset.to_offset(&self.buffer_snapshot);
 607        let mut cursor = self.transforms.cursor::<usize>();
 608        cursor.seek(&offset, Bias::Right, &());
 609        cursor.item().map_or(false, |t| t.output_text.is_some())
 610    }
 611
 612    pub fn is_line_folded(&self, output_row: u32) -> bool {
 613        let mut cursor = self.transforms.cursor::<FoldPoint>();
 614        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 615        while let Some(transform) = cursor.item() {
 616            if transform.output_text.is_some() {
 617                return true;
 618            }
 619            if cursor.end(&()).row() == output_row {
 620                cursor.next(&())
 621            } else {
 622                break;
 623            }
 624        }
 625        false
 626    }
 627
 628    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 629        let start = start.to_offset(self);
 630        self.chunks(start..self.len(), None)
 631            .flat_map(|chunk| chunk.text.chars())
 632    }
 633
 634    pub fn chunks<'a>(
 635        &'a self,
 636        range: Range<FoldOffset>,
 637        theme: Option<&'a SyntaxTheme>,
 638    ) -> Chunks<'a> {
 639        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 640
 641        transform_cursor.seek(&range.end, Bias::Right, &());
 642        let overshoot = range.end.0 - transform_cursor.start().0 .0;
 643        let buffer_end = transform_cursor.start().1 + overshoot;
 644
 645        transform_cursor.seek(&range.start, Bias::Right, &());
 646        let overshoot = range.start.0 - transform_cursor.start().0 .0;
 647        let buffer_start = transform_cursor.start().1 + overshoot;
 648
 649        Chunks {
 650            transform_cursor,
 651            buffer_chunks: self.buffer_snapshot.chunks(buffer_start..buffer_end, theme),
 652            buffer_chunk: None,
 653            buffer_offset: buffer_start,
 654            output_offset: range.start.0,
 655            max_output_offset: range.end.0,
 656        }
 657    }
 658
 659    #[cfg(test)]
 660    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 661        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 662        cursor.seek(&offset, Bias::Right, &());
 663        if let Some(transform) = cursor.item() {
 664            let transform_start = cursor.start().0 .0;
 665            if transform.output_text.is_some() {
 666                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 667                    FoldOffset(transform_start)
 668                } else {
 669                    FoldOffset(cursor.end(&()).0 .0)
 670                }
 671            } else {
 672                let overshoot = offset.0 - transform_start;
 673                let buffer_offset = cursor.start().1 + overshoot;
 674                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 675                FoldOffset(
 676                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 677                        as usize,
 678                )
 679            }
 680        } else {
 681            FoldOffset(self.transforms.summary().output.bytes)
 682        }
 683    }
 684
 685    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 686        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 687        cursor.seek(&point, Bias::Right, &());
 688        if let Some(transform) = cursor.item() {
 689            let transform_start = cursor.start().0 .0;
 690            if transform.output_text.is_some() {
 691                if point.0 == transform_start || matches!(bias, Bias::Left) {
 692                    FoldPoint(transform_start)
 693                } else {
 694                    FoldPoint(cursor.end(&()).0 .0)
 695                }
 696            } else {
 697                let overshoot = point.0 - transform_start;
 698                let buffer_position = cursor.start().1 + overshoot;
 699                let clipped_buffer_position =
 700                    self.buffer_snapshot.clip_point(buffer_position, bias);
 701                FoldPoint::new(
 702                    point.row(),
 703                    ((point.column() as i32) + clipped_buffer_position.column as i32
 704                        - buffer_position.column as i32) as u32,
 705                )
 706            }
 707        } else {
 708            FoldPoint(self.transforms.summary().output.lines)
 709        }
 710    }
 711}
 712
 713fn intersecting_folds<'a, T>(
 714    buffer: &'a text::Snapshot,
 715    folds: &'a SumTree<Fold>,
 716    range: Range<T>,
 717    inclusive: bool,
 718) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 719where
 720    T: ToOffset,
 721{
 722    let start = buffer.anchor_before(range.start.to_offset(buffer));
 723    let end = buffer.anchor_after(range.end.to_offset(buffer));
 724    folds.filter::<_, usize>(
 725        move |summary| {
 726            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 727            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 728
 729            if inclusive {
 730                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 731            } else {
 732                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 733            }
 734        },
 735        buffer,
 736    )
 737}
 738
 739fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 740    edits.sort_unstable_by(|a, b| {
 741        a.old
 742            .start
 743            .cmp(&b.old.start)
 744            .then_with(|| b.old.end.cmp(&a.old.end))
 745    });
 746
 747    let mut i = 1;
 748    while i < edits.len() {
 749        let edit = edits[i].clone();
 750        let prev_edit = &mut edits[i - 1];
 751        if prev_edit.old.end >= edit.old.start {
 752            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 753            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 754            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 755            edits.remove(i);
 756            continue;
 757        }
 758        i += 1;
 759    }
 760}
 761
 762fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 763    edits.sort_unstable_by(|a, b| {
 764        a.old_bytes
 765            .start
 766            .cmp(&b.old_bytes.start)
 767            .then_with(|| b.old_bytes.end.cmp(&a.old_bytes.end))
 768    });
 769
 770    let mut i = 1;
 771    while i < edits.len() {
 772        let edit = edits[i].clone();
 773        let prev_edit = &mut edits[i - 1];
 774        if prev_edit.old_bytes.end >= edit.old_bytes.start {
 775            prev_edit.old_bytes.end = prev_edit.old_bytes.end.max(edit.old_bytes.end);
 776            prev_edit.new_bytes.start = prev_edit.new_bytes.start.min(edit.new_bytes.start);
 777            prev_edit.new_bytes.end = prev_edit.new_bytes.end.max(edit.new_bytes.end);
 778            edits.remove(i);
 779            continue;
 780        }
 781        i += 1;
 782    }
 783}
 784
 785#[derive(Clone, Debug, Default, Eq, PartialEq)]
 786struct Transform {
 787    summary: TransformSummary,
 788    output_text: Option<&'static str>,
 789}
 790
 791impl Transform {
 792    fn is_fold(&self) -> bool {
 793        self.output_text.is_some()
 794    }
 795}
 796
 797#[derive(Clone, Debug, Default, Eq, PartialEq)]
 798struct TransformSummary {
 799    output: TextSummary,
 800    input: TextSummary,
 801}
 802
 803impl sum_tree::Item for Transform {
 804    type Summary = TransformSummary;
 805
 806    fn summary(&self) -> Self::Summary {
 807        self.summary.clone()
 808    }
 809}
 810
 811impl sum_tree::Summary for TransformSummary {
 812    type Context = ();
 813
 814    fn add_summary(&mut self, other: &Self, _: &()) {
 815        self.input += &other.input;
 816        self.output += &other.output;
 817    }
 818}
 819
 820#[derive(Clone, Debug)]
 821struct Fold(Range<Anchor>);
 822
 823impl Default for Fold {
 824    fn default() -> Self {
 825        Self(Anchor::min()..Anchor::max())
 826    }
 827}
 828
 829impl sum_tree::Item for Fold {
 830    type Summary = FoldSummary;
 831
 832    fn summary(&self) -> Self::Summary {
 833        FoldSummary {
 834            start: self.0.start.clone(),
 835            end: self.0.end.clone(),
 836            min_start: self.0.start.clone(),
 837            max_end: self.0.end.clone(),
 838            count: 1,
 839        }
 840    }
 841}
 842
 843#[derive(Clone, Debug)]
 844struct FoldSummary {
 845    start: Anchor,
 846    end: Anchor,
 847    min_start: Anchor,
 848    max_end: Anchor,
 849    count: usize,
 850}
 851
 852impl Default for FoldSummary {
 853    fn default() -> Self {
 854        Self {
 855            start: Anchor::min(),
 856            end: Anchor::max(),
 857            min_start: Anchor::max(),
 858            max_end: Anchor::min(),
 859            count: 0,
 860        }
 861    }
 862}
 863
 864impl sum_tree::Summary for FoldSummary {
 865    type Context = text::Snapshot;
 866
 867    fn add_summary(&mut self, other: &Self, buffer: &text::Snapshot) {
 868        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 869            self.min_start = other.min_start.clone();
 870        }
 871        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 872            self.max_end = other.max_end.clone();
 873        }
 874
 875        #[cfg(debug_assertions)]
 876        {
 877            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 878            assert!(start_comparison <= Ordering::Equal);
 879            if start_comparison == Ordering::Equal {
 880                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 881            }
 882        }
 883
 884        self.start = other.start.clone();
 885        self.end = other.end.clone();
 886        self.count += other.count;
 887    }
 888}
 889
 890impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 891    fn add_summary(&mut self, summary: &'a FoldSummary, _: &text::Snapshot) {
 892        self.0.start = summary.start.clone();
 893        self.0.end = summary.end.clone();
 894    }
 895}
 896
 897impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 898    fn cmp(&self, other: &Self, buffer: &text::Snapshot) -> Ordering {
 899        self.0.cmp(&other.0, buffer).unwrap()
 900    }
 901}
 902
 903impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 904    fn add_summary(&mut self, summary: &'a FoldSummary, _: &text::Snapshot) {
 905        *self += summary.count;
 906    }
 907}
 908
 909pub struct BufferRows<'a> {
 910    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 911    fold_point: FoldPoint,
 912}
 913
 914impl<'a> Iterator for BufferRows<'a> {
 915    type Item = u32;
 916
 917    fn next(&mut self) -> Option<Self::Item> {
 918        while self.fold_point > self.cursor.end(&()).0 {
 919            self.cursor.next(&());
 920            if self.cursor.item().is_none() {
 921                // TODO: Return a bool from next?
 922                break;
 923            }
 924        }
 925
 926        if self.cursor.item().is_some() {
 927            let overshoot = self.fold_point.0 - self.cursor.start().0 .0;
 928            let buffer_point = self.cursor.start().1 + overshoot;
 929            *self.fold_point.row_mut() += 1;
 930            Some(buffer_point.row)
 931        } else {
 932            None
 933        }
 934    }
 935}
 936
 937pub struct Chunks<'a> {
 938    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 939    buffer_chunks: language::Chunks<'a>,
 940    buffer_chunk: Option<(usize, Chunk<'a>)>,
 941    buffer_offset: usize,
 942    output_offset: usize,
 943    max_output_offset: usize,
 944}
 945
 946impl<'a> Iterator for Chunks<'a> {
 947    type Item = Chunk<'a>;
 948
 949    fn next(&mut self) -> Option<Self::Item> {
 950        if self.output_offset >= self.max_output_offset {
 951            return None;
 952        }
 953
 954        let transform = if let Some(item) = self.transform_cursor.item() {
 955            item
 956        } else {
 957            return None;
 958        };
 959
 960        // If we're in a fold, then return the fold's display text and
 961        // advance the transform and buffer cursors to the end of the fold.
 962        if let Some(output_text) = transform.output_text {
 963            self.buffer_chunk.take();
 964            self.buffer_offset += transform.summary.input.bytes;
 965            self.buffer_chunks.seek(self.buffer_offset);
 966
 967            while self.buffer_offset >= self.transform_cursor.end(&()).1
 968                && self.transform_cursor.item().is_some()
 969            {
 970                self.transform_cursor.next(&());
 971            }
 972
 973            self.output_offset += output_text.len();
 974            return Some(Chunk {
 975                text: output_text,
 976                highlight_style: None,
 977                diagnostic: None,
 978            });
 979        }
 980
 981        // Retrieve a chunk from the current location in the buffer.
 982        if self.buffer_chunk.is_none() {
 983            let chunk_offset = self.buffer_chunks.offset();
 984            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
 985        }
 986
 987        // Otherwise, take a chunk from the buffer's text.
 988        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
 989            let offset_in_chunk = self.buffer_offset - chunk_offset;
 990            chunk.text = &chunk.text[offset_in_chunk..];
 991
 992            // Truncate the chunk so that it ends at the next fold.
 993            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 994            if chunk.text.len() >= region_end {
 995                chunk.text = &chunk.text[0..region_end];
 996                self.transform_cursor.next(&());
 997            } else {
 998                self.buffer_chunk.take();
 999            }
1000
1001            self.buffer_offset += chunk.text.len();
1002            self.output_offset += chunk.text.len();
1003            return Some(chunk);
1004        }
1005
1006        None
1007    }
1008}
1009
1010impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1011    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1012        self.0 += &summary.output.lines;
1013    }
1014}
1015
1016#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1017pub struct FoldOffset(pub usize);
1018
1019impl FoldOffset {
1020    pub fn to_point(&self, snapshot: &Snapshot) -> FoldPoint {
1021        let mut cursor = snapshot
1022            .transforms
1023            .cursor::<(FoldOffset, TransformSummary)>();
1024        cursor.seek(self, Bias::Right, &());
1025        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1026            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1027        } else {
1028            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1029            let buffer_point = snapshot.buffer_snapshot.to_point(buffer_offset);
1030            buffer_point - cursor.start().1.input.lines
1031        };
1032        FoldPoint(cursor.start().1.output.lines + overshoot)
1033    }
1034}
1035
1036impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1037    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1038        self.0 += &summary.output.bytes;
1039    }
1040}
1041
1042impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1043    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1044        *self += &summary.input.lines;
1045    }
1046}
1047
1048impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1049    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1050        *self += &summary.input.bytes;
1051    }
1052}
1053
1054#[derive(Clone, Debug, PartialEq, Eq)]
1055pub struct FoldEdit {
1056    pub old_bytes: Range<FoldOffset>,
1057    pub new_bytes: Range<FoldOffset>,
1058}
1059
1060#[cfg(test)]
1061impl FoldEdit {
1062    pub fn delta(&self) -> isize {
1063        self.inserted_bytes() as isize - self.deleted_bytes() as isize
1064    }
1065
1066    pub fn deleted_bytes(&self) -> usize {
1067        self.old_bytes.end.0 - self.old_bytes.start.0
1068    }
1069
1070    pub fn inserted_bytes(&self) -> usize {
1071        self.new_bytes.end.0 - self.new_bytes.start.0
1072    }
1073}
1074
1075#[cfg(test)]
1076mod tests {
1077    use super::*;
1078    use crate::{test::sample_text, ToPoint};
1079    use rand::prelude::*;
1080    use std::{env, mem};
1081    use text::RandomCharIter;
1082    use Bias::{Left, Right};
1083
1084    #[gpui::test]
1085    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1086        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1087        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1088
1089        let (mut writer, _, _) = map.write(cx.as_ref());
1090        let (snapshot2, edits) = writer.fold(
1091            vec![
1092                Point::new(0, 2)..Point::new(2, 2),
1093                Point::new(2, 4)..Point::new(4, 1),
1094            ],
1095            cx.as_ref(),
1096        );
1097        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1098        assert_eq!(
1099            edits,
1100            &[
1101                FoldEdit {
1102                    old_bytes: FoldOffset(2)..FoldOffset(16),
1103                    new_bytes: FoldOffset(2)..FoldOffset(5),
1104                },
1105                FoldEdit {
1106                    old_bytes: FoldOffset(18)..FoldOffset(29),
1107                    new_bytes: FoldOffset(7)..FoldOffset(10)
1108                },
1109            ]
1110        );
1111
1112        buffer.update(cx, |buffer, cx| {
1113            buffer.edit(
1114                vec![
1115                    Point::new(0, 0)..Point::new(0, 1),
1116                    Point::new(2, 3)..Point::new(2, 3),
1117                ],
1118                "123",
1119                cx,
1120            );
1121        });
1122        let (snapshot3, edits) = map.read(cx.as_ref());
1123        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1124        assert_eq!(
1125            edits,
1126            &[
1127                FoldEdit {
1128                    old_bytes: FoldOffset(0)..FoldOffset(1),
1129                    new_bytes: FoldOffset(0)..FoldOffset(3),
1130                },
1131                FoldEdit {
1132                    old_bytes: FoldOffset(6)..FoldOffset(6),
1133                    new_bytes: FoldOffset(8)..FoldOffset(11),
1134                },
1135            ]
1136        );
1137
1138        buffer.update(cx, |buffer, cx| {
1139            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx)
1140        });
1141        let (snapshot4, _) = map.read(cx.as_ref());
1142        assert_eq!(snapshot4.text(), "123a…c123456eee");
1143
1144        let (mut writer, _, _) = map.write(cx.as_ref());
1145        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)), cx.as_ref());
1146        let (snapshot5, _) = map.read(cx.as_ref());
1147        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1148    }
1149
1150    #[gpui::test]
1151    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1152        let buffer = cx.add_model(|cx| Buffer::new(0, "abcdefghijkl", cx));
1153
1154        {
1155            let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1156
1157            let (mut writer, _, _) = map.write(cx.as_ref());
1158            writer.fold(vec![5..8], cx.as_ref());
1159            let (snapshot, _) = map.read(cx.as_ref());
1160            assert_eq!(snapshot.text(), "abcde…ijkl");
1161
1162            // Create an fold adjacent to the start of the first fold.
1163            let (mut writer, _, _) = map.write(cx.as_ref());
1164            writer.fold(vec![0..1, 2..5], cx.as_ref());
1165            let (snapshot, _) = map.read(cx.as_ref());
1166            assert_eq!(snapshot.text(), "…b…ijkl");
1167
1168            // Create an fold adjacent to the end of the first fold.
1169            let (mut writer, _, _) = map.write(cx.as_ref());
1170            writer.fold(vec![11..11, 8..10], cx.as_ref());
1171            let (snapshot, _) = map.read(cx.as_ref());
1172            assert_eq!(snapshot.text(), "…b…kl");
1173        }
1174
1175        {
1176            let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1177
1178            // Create two adjacent folds.
1179            let (mut writer, _, _) = map.write(cx.as_ref());
1180            writer.fold(vec![0..2, 2..5], cx.as_ref());
1181            let (snapshot, _) = map.read(cx.as_ref());
1182            assert_eq!(snapshot.text(), "…fghijkl");
1183
1184            // Edit within one of the folds.
1185            buffer.update(cx, |buffer, cx| buffer.edit(vec![0..1], "12345", cx));
1186            let (snapshot, _) = map.read(cx.as_ref());
1187            assert_eq!(snapshot.text(), "12345…fghijkl");
1188        }
1189    }
1190
1191    #[gpui::test]
1192    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1193        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1194        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1195        let (mut writer, _, _) = map.write(cx.as_ref());
1196        writer.fold(
1197            vec![
1198                Point::new(0, 2)..Point::new(2, 2),
1199                Point::new(0, 4)..Point::new(1, 0),
1200                Point::new(1, 2)..Point::new(3, 2),
1201                Point::new(3, 1)..Point::new(4, 1),
1202            ],
1203            cx.as_ref(),
1204        );
1205        let (snapshot, _) = map.read(cx.as_ref());
1206        assert_eq!(snapshot.text(), "aa…eeeee");
1207    }
1208
1209    #[gpui::test]
1210    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1211        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
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(
1216            vec![
1217                Point::new(0, 2)..Point::new(2, 2),
1218                Point::new(3, 1)..Point::new(4, 1),
1219            ],
1220            cx.as_ref(),
1221        );
1222        let (snapshot, _) = map.read(cx.as_ref());
1223        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1224
1225        buffer.update(cx, |buffer, cx| {
1226            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx)
1227        });
1228        let (snapshot, _) = map.read(cx.as_ref());
1229        assert_eq!(snapshot.text(), "aa…eeeee");
1230    }
1231
1232    #[gpui::test]
1233    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1234        let buffer = cx.add_model(|cx| Buffer::new(0, sample_text(5, 6), cx));
1235        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1236        let buffer = buffer.read(cx);
1237
1238        let (mut writer, _, _) = map.write(cx.as_ref());
1239        writer.fold(
1240            vec![
1241                Point::new(0, 2)..Point::new(2, 2),
1242                Point::new(0, 4)..Point::new(1, 0),
1243                Point::new(1, 2)..Point::new(3, 2),
1244                Point::new(3, 1)..Point::new(4, 1),
1245            ],
1246            cx.as_ref(),
1247        );
1248        let (snapshot, _) = map.read(cx.as_ref());
1249        let fold_ranges = snapshot
1250            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1251            .map(|fold| fold.start.to_point(buffer)..fold.end.to_point(buffer))
1252            .collect::<Vec<_>>();
1253        assert_eq!(
1254            fold_ranges,
1255            vec![
1256                Point::new(0, 2)..Point::new(2, 2),
1257                Point::new(1, 2)..Point::new(3, 2)
1258            ]
1259        );
1260    }
1261
1262    #[gpui::test(iterations = 100)]
1263    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1264        let operations = env::var("OPERATIONS")
1265            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1266            .unwrap_or(10);
1267
1268        let buffer = cx.add_model(|cx| {
1269            let len = rng.gen_range(0..10);
1270            let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1271            Buffer::new(0, text, cx)
1272        });
1273        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1274
1275        let (mut initial_snapshot, _) = map.read(cx.as_ref());
1276        let mut snapshot_edits = Vec::new();
1277
1278        for _ in 0..operations {
1279            log::info!("text: {:?}", buffer.read(cx).text());
1280            match rng.gen_range(0..=100) {
1281                0..=59 => {
1282                    snapshot_edits.extend(map.randomly_mutate(&mut rng, cx.as_ref()));
1283                }
1284                _ => {
1285                    let edits = buffer.update(cx, |buffer, _| {
1286                        let start_version = buffer.version.clone();
1287                        let edit_count = rng.gen_range(1..=5);
1288                        buffer.randomly_edit(&mut rng, edit_count);
1289                        buffer
1290                            .edits_since::<Point>(&start_version)
1291                            .collect::<Vec<_>>()
1292                    });
1293                    log::info!("editing {:?}", edits);
1294                }
1295            }
1296
1297            let buffer = map.buffer.read(cx).snapshot();
1298            let mut expected_text: String = buffer.text().to_string();
1299            let mut expected_buffer_rows = Vec::new();
1300            let mut next_row = buffer.max_point().row;
1301            for fold_range in map.merged_fold_ranges(cx.as_ref()).into_iter().rev() {
1302                let fold_start = buffer.point_for_offset(fold_range.start).unwrap();
1303                let fold_end = buffer.point_for_offset(fold_range.end).unwrap();
1304                expected_buffer_rows.extend((fold_end.row + 1..=next_row).rev());
1305                next_row = fold_start.row;
1306
1307                expected_text.replace_range(fold_range.start..fold_range.end, "…");
1308            }
1309            expected_buffer_rows.extend((0..=next_row).rev());
1310            expected_buffer_rows.reverse();
1311
1312            let (snapshot, edits) = map.read(cx.as_ref());
1313            assert_eq!(snapshot.text(), expected_text);
1314            snapshot_edits.push((snapshot.clone(), edits));
1315
1316            for (output_row, line) in expected_text.lines().enumerate() {
1317                let line_len = snapshot.line_len(output_row as u32);
1318                assert_eq!(line_len, line.len() as u32);
1319            }
1320
1321            let longest_row = snapshot.longest_row();
1322            let longest_char_column = expected_text
1323                .split('\n')
1324                .nth(longest_row as usize)
1325                .unwrap()
1326                .chars()
1327                .count();
1328            let mut fold_point = FoldPoint::new(0, 0);
1329            let mut fold_offset = FoldOffset(0);
1330            let mut char_column = 0;
1331            for c in expected_text.chars() {
1332                let buffer_point = fold_point.to_buffer_point(&snapshot);
1333                let buffer_offset = buffer_point.to_offset(&buffer);
1334                assert_eq!(
1335                    buffer_point.to_fold_point(&snapshot, Right),
1336                    fold_point,
1337                    "{:?} -> fold point",
1338                    buffer_point,
1339                );
1340                assert_eq!(
1341                    fold_point.to_buffer_offset(&snapshot),
1342                    buffer_offset,
1343                    "fold_point.to_buffer_offset({:?})",
1344                    fold_point,
1345                );
1346                assert_eq!(
1347                    fold_point.to_offset(&snapshot),
1348                    fold_offset,
1349                    "fold_point.to_offset({:?})",
1350                    fold_point,
1351                );
1352
1353                if c == '\n' {
1354                    *fold_point.row_mut() += 1;
1355                    *fold_point.column_mut() = 0;
1356                    char_column = 0;
1357                } else {
1358                    *fold_point.column_mut() += c.len_utf8() as u32;
1359                    char_column += 1;
1360                }
1361                fold_offset.0 += c.len_utf8();
1362                if char_column > longest_char_column {
1363                    panic!(
1364                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1365                        longest_row,
1366                        longest_char_column,
1367                        fold_point.row(),
1368                        char_column
1369                    );
1370                }
1371            }
1372
1373            for _ in 0..5 {
1374                let mut start = snapshot
1375                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1376                let mut end = snapshot
1377                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1378                if start > end {
1379                    mem::swap(&mut start, &mut end);
1380                }
1381
1382                let text = &expected_text[start.0..end.0];
1383                log::info!("slicing {:?}..{:?} (text: {:?})", start, end, text);
1384                assert_eq!(
1385                    snapshot
1386                        .chunks(start..end, None)
1387                        .map(|c| c.text)
1388                        .collect::<String>(),
1389                    text,
1390                );
1391            }
1392
1393            for (idx, buffer_row) in expected_buffer_rows.iter().enumerate() {
1394                let fold_row = Point::new(*buffer_row, 0)
1395                    .to_fold_point(&snapshot, Right)
1396                    .row();
1397                assert_eq!(
1398                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1399                    expected_buffer_rows[idx..],
1400                );
1401            }
1402
1403            for fold_range in map.merged_fold_ranges(cx.as_ref()) {
1404                let fold_point = fold_range
1405                    .start
1406                    .to_point(&buffer)
1407                    .to_fold_point(&snapshot, Right);
1408                assert!(snapshot.is_line_folded(fold_point.row()));
1409            }
1410
1411            for _ in 0..5 {
1412                let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1413                let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1414                let expected_folds = map
1415                    .folds
1416                    .items(&buffer)
1417                    .into_iter()
1418                    .filter(|fold| {
1419                        let start = buffer.anchor_before(start);
1420                        let end = buffer.anchor_after(end);
1421                        start.cmp(&fold.0.end, &buffer).unwrap() == Ordering::Less
1422                            && end.cmp(&fold.0.start, &buffer).unwrap() == Ordering::Greater
1423                    })
1424                    .map(|fold| fold.0)
1425                    .collect::<Vec<_>>();
1426
1427                assert_eq!(
1428                    snapshot
1429                        .folds_in_range(start..end)
1430                        .cloned()
1431                        .collect::<Vec<_>>(),
1432                    expected_folds
1433                );
1434            }
1435
1436            let text = snapshot.text();
1437            for _ in 0..5 {
1438                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1439                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1440                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1441                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1442                let mut start =
1443                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1444                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1445                if start > end {
1446                    mem::swap(&mut start, &mut end);
1447                }
1448
1449                let lines = start..end;
1450                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1451                assert_eq!(
1452                    snapshot.text_summary_for_range(lines),
1453                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1454                )
1455            }
1456
1457            let mut text = initial_snapshot.text();
1458            for (snapshot, edits) in snapshot_edits.drain(..) {
1459                let new_text = snapshot.text();
1460                let mut delta = 0isize;
1461                for edit in edits {
1462                    let old_bytes = ((edit.old_bytes.start.0 as isize) + delta) as usize
1463                        ..((edit.old_bytes.end.0 as isize) + delta) as usize;
1464                    let new_bytes = edit.new_bytes.start.0..edit.new_bytes.end.0;
1465                    delta += edit.delta();
1466                    text.replace_range(old_bytes, &new_text[new_bytes]);
1467                }
1468
1469                assert_eq!(text, new_text);
1470                initial_snapshot = snapshot;
1471            }
1472        }
1473    }
1474
1475    #[gpui::test]
1476    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1477        let text = sample_text(6, 6) + "\n";
1478        let buffer = cx.add_model(|cx| Buffer::new(0, text, cx));
1479
1480        let mut map = FoldMap::new(buffer.clone(), cx.as_ref()).0;
1481
1482        let (mut writer, _, _) = map.write(cx.as_ref());
1483        writer.fold(
1484            vec![
1485                Point::new(0, 2)..Point::new(2, 2),
1486                Point::new(3, 1)..Point::new(4, 1),
1487            ],
1488            cx.as_ref(),
1489        );
1490
1491        let (snapshot, _) = map.read(cx.as_ref());
1492        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1493        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), [0, 3, 5, 6]);
1494        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [6]);
1495    }
1496
1497    impl FoldMap {
1498        fn merged_fold_ranges(&self, cx: &AppContext) -> Vec<Range<usize>> {
1499            let buffer = self.buffer.read(cx).snapshot();
1500            let mut folds = self.folds.items(&buffer);
1501            // Ensure sorting doesn't change how folds get merged and displayed.
1502            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1503            let mut fold_ranges = folds
1504                .iter()
1505                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1506                .peekable();
1507
1508            let mut merged_ranges = Vec::new();
1509            while let Some(mut fold_range) = fold_ranges.next() {
1510                while let Some(next_range) = fold_ranges.peek() {
1511                    if fold_range.end >= next_range.start {
1512                        if next_range.end > fold_range.end {
1513                            fold_range.end = next_range.end;
1514                        }
1515                        fold_ranges.next();
1516                    } else {
1517                        break;
1518                    }
1519                }
1520                if fold_range.end > fold_range.start {
1521                    merged_ranges.push(fold_range);
1522                }
1523            }
1524            merged_ranges
1525        }
1526
1527        pub fn randomly_mutate(
1528            &mut self,
1529            rng: &mut impl Rng,
1530            cx: &AppContext,
1531        ) -> Vec<(Snapshot, Vec<FoldEdit>)> {
1532            let mut snapshot_edits = Vec::new();
1533            match rng.gen_range(0..=100) {
1534                0..=39 if !self.folds.is_empty() => {
1535                    let buffer = self.buffer.read(cx);
1536                    let mut to_unfold = Vec::new();
1537                    for _ in 0..rng.gen_range(1..=3) {
1538                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1539                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1540                        to_unfold.push(start..end);
1541                    }
1542                    log::info!("unfolding {:?}", to_unfold);
1543                    let (mut writer, snapshot, edits) = self.write(cx.as_ref());
1544                    snapshot_edits.push((snapshot, edits));
1545                    let (snapshot, edits) = writer.fold(to_unfold, cx.as_ref());
1546                    snapshot_edits.push((snapshot, edits));
1547                }
1548                _ => {
1549                    let buffer = self.buffer.read(cx);
1550                    let mut to_fold = Vec::new();
1551                    for _ in 0..rng.gen_range(1..=2) {
1552                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1553                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1554                        to_fold.push(start..end);
1555                    }
1556                    log::info!("folding {:?}", to_fold);
1557                    let (mut writer, snapshot, edits) = self.write(cx.as_ref());
1558                    snapshot_edits.push((snapshot, edits));
1559                    let (snapshot, edits) = writer.fold(to_fold, cx.as_ref());
1560                    snapshot_edits.push((snapshot, edits));
1561                }
1562            }
1563            snapshot_edits
1564        }
1565    }
1566}