1use crate::{Anchor, AnchorRangeExt, MultiBufferChunks, MultiBufferSnapshot, ToOffset};
   2use language::{Chunk, Edit, Point, PointUtf16, TextSummary};
   3use parking_lot::Mutex;
   4use std::{
   5    cmp::{self, Ordering},
   6    iter,
   7    ops::{Range, Sub},
   8    sync::atomic::{AtomicUsize, Ordering::SeqCst},
   9};
  10use sum_tree::{Bias, Cursor, FilterCursor, SumTree};
  11use theme::SyntaxTheme;
  12
  13pub trait ToFoldPoint {
  14    fn to_fold_point(&self, snapshot: &FoldSnapshot, bias: Bias) -> FoldPoint;
  15}
  16
  17#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  18pub struct FoldPoint(pub super::Point);
  19
  20impl FoldPoint {
  21    pub fn new(row: u32, column: u32) -> Self {
  22        Self(super::Point::new(row, column))
  23    }
  24
  25    pub fn row(self) -> u32 {
  26        self.0.row
  27    }
  28
  29    pub fn column(self) -> u32 {
  30        self.0.column
  31    }
  32
  33    pub fn row_mut(&mut self) -> &mut u32 {
  34        &mut self.0.row
  35    }
  36
  37    #[cfg(test)]
  38    pub fn column_mut(&mut self) -> &mut u32 {
  39        &mut self.0.column
  40    }
  41
  42    pub fn to_buffer_point(&self, snapshot: &FoldSnapshot) -> Point {
  43        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  44        cursor.seek(self, Bias::Right, &());
  45        let overshoot = self.0 - cursor.start().0 .0;
  46        cursor.start().1 + overshoot
  47    }
  48
  49    pub fn to_buffer_offset(&self, snapshot: &FoldSnapshot) -> usize {
  50        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, Point)>();
  51        cursor.seek(self, Bias::Right, &());
  52        let overshoot = self.0 - cursor.start().0 .0;
  53        snapshot
  54            .buffer_snapshot
  55            .point_to_offset(cursor.start().1 + overshoot)
  56    }
  57
  58    pub fn to_offset(&self, snapshot: &FoldSnapshot) -> FoldOffset {
  59        let mut cursor = snapshot
  60            .transforms
  61            .cursor::<(FoldPoint, TransformSummary)>();
  62        cursor.seek(self, Bias::Right, &());
  63        let overshoot = self.0 - cursor.start().1.output.lines;
  64        let mut offset = cursor.start().1.output.bytes;
  65        if !overshoot.is_zero() {
  66            let transform = cursor.item().expect("display point out of range");
  67            assert!(transform.output_text.is_none());
  68            let end_buffer_offset = snapshot
  69                .buffer_snapshot
  70                .point_to_offset(cursor.start().1.input.lines + overshoot);
  71            offset += end_buffer_offset - cursor.start().1.input.bytes;
  72        }
  73        FoldOffset(offset)
  74    }
  75}
  76
  77impl ToFoldPoint for Point {
  78    fn to_fold_point(&self, snapshot: &FoldSnapshot, bias: Bias) -> FoldPoint {
  79        let mut cursor = snapshot.transforms.cursor::<(Point, FoldPoint)>();
  80        cursor.seek(self, Bias::Right, &());
  81        if cursor.item().map_or(false, |t| t.is_fold()) {
  82            if bias == Bias::Left || *self == cursor.start().0 {
  83                cursor.start().1
  84            } else {
  85                cursor.end(&()).1
  86            }
  87        } else {
  88            let overshoot = *self - cursor.start().0;
  89            FoldPoint(cmp::min(
  90                cursor.start().1 .0 + overshoot,
  91                cursor.end(&()).1 .0,
  92            ))
  93        }
  94    }
  95}
  96
  97pub struct FoldMapWriter<'a>(&'a mut FoldMap);
  98
  99impl<'a> FoldMapWriter<'a> {
 100    pub fn fold<T: ToOffset>(
 101        &mut self,
 102        ranges: impl IntoIterator<Item = Range<T>>,
 103    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 104        let mut edits = Vec::new();
 105        let mut folds = Vec::new();
 106        let buffer = self.0.buffer.lock().clone();
 107        for range in ranges.into_iter() {
 108            let range = range.start.to_offset(&buffer)..range.end.to_offset(&buffer);
 109            if range.start != range.end {
 110                let fold = Fold(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 111                folds.push(fold);
 112                edits.push(text::Edit {
 113                    old: range.clone(),
 114                    new: range,
 115                });
 116            }
 117        }
 118
 119        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(a, b, &buffer));
 120
 121        self.0.folds = {
 122            let mut new_tree = SumTree::new();
 123            let mut cursor = self.0.folds.cursor::<Fold>();
 124            for fold in folds {
 125                new_tree.push_tree(cursor.slice(&fold, Bias::Right, &buffer), &buffer);
 126                new_tree.push(fold, &buffer);
 127            }
 128            new_tree.push_tree(cursor.suffix(&buffer), &buffer);
 129            new_tree
 130        };
 131
 132        consolidate_buffer_edits(&mut edits);
 133        let edits = self.0.sync(buffer.clone(), edits);
 134        let snapshot = FoldSnapshot {
 135            transforms: self.0.transforms.lock().clone(),
 136            folds: self.0.folds.clone(),
 137            buffer_snapshot: buffer,
 138            version: self.0.version.load(SeqCst),
 139        };
 140        (snapshot, edits)
 141    }
 142
 143    pub fn unfold<T: ToOffset>(
 144        &mut self,
 145        ranges: impl IntoIterator<Item = Range<T>>,
 146    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 147        let mut edits = Vec::new();
 148        let mut fold_ixs_to_delete = Vec::new();
 149        let buffer = self.0.buffer.lock().clone();
 150        for range in ranges.into_iter() {
 151            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 152            let mut folds_cursor = intersecting_folds(&buffer, &self.0.folds, range, true);
 153            while let Some(fold) = folds_cursor.item() {
 154                let offset_range = fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer);
 155                edits.push(text::Edit {
 156                    old: offset_range.clone(),
 157                    new: offset_range,
 158                });
 159                fold_ixs_to_delete.push(*folds_cursor.start());
 160                folds_cursor.next(&buffer);
 161            }
 162        }
 163
 164        fold_ixs_to_delete.sort_unstable();
 165        fold_ixs_to_delete.dedup();
 166
 167        self.0.folds = {
 168            let mut cursor = self.0.folds.cursor::<usize>();
 169            let mut folds = SumTree::new();
 170            for fold_ix in fold_ixs_to_delete {
 171                folds.push_tree(cursor.slice(&fold_ix, Bias::Right, &buffer), &buffer);
 172                cursor.next(&buffer);
 173            }
 174            folds.push_tree(cursor.suffix(&buffer), &buffer);
 175            folds
 176        };
 177
 178        consolidate_buffer_edits(&mut edits);
 179        let edits = self.0.sync(buffer.clone(), edits);
 180        let snapshot = FoldSnapshot {
 181            transforms: self.0.transforms.lock().clone(),
 182            folds: self.0.folds.clone(),
 183            buffer_snapshot: buffer,
 184            version: self.0.version.load(SeqCst),
 185        };
 186        (snapshot, edits)
 187    }
 188}
 189
 190pub struct FoldMap {
 191    buffer: Mutex<MultiBufferSnapshot>,
 192    transforms: Mutex<SumTree<Transform>>,
 193    folds: SumTree<Fold>,
 194    version: AtomicUsize,
 195}
 196
 197impl FoldMap {
 198    pub fn new(buffer: MultiBufferSnapshot) -> (Self, FoldSnapshot) {
 199        let this = Self {
 200            buffer: Mutex::new(buffer.clone()),
 201            folds: Default::default(),
 202            transforms: Mutex::new(SumTree::from_item(
 203                Transform {
 204                    summary: TransformSummary {
 205                        input: buffer.text_summary(),
 206                        output: buffer.text_summary(),
 207                    },
 208                    output_text: None,
 209                },
 210                &(),
 211            )),
 212            version: Default::default(),
 213        };
 214
 215        let snapshot = FoldSnapshot {
 216            transforms: this.transforms.lock().clone(),
 217            folds: this.folds.clone(),
 218            buffer_snapshot: this.buffer.lock().clone(),
 219            version: this.version.load(SeqCst),
 220        };
 221        (this, snapshot)
 222    }
 223
 224    pub fn read(
 225        &self,
 226        buffer: MultiBufferSnapshot,
 227        edits: Vec<Edit<usize>>,
 228    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 229        let edits = self.sync(buffer, edits);
 230        self.check_invariants();
 231        let snapshot = FoldSnapshot {
 232            transforms: self.transforms.lock().clone(),
 233            folds: self.folds.clone(),
 234            buffer_snapshot: self.buffer.lock().clone(),
 235            version: self.version.load(SeqCst),
 236        };
 237        (snapshot, edits)
 238    }
 239
 240    pub fn write(
 241        &mut self,
 242        buffer: MultiBufferSnapshot,
 243        edits: Vec<Edit<usize>>,
 244    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 245        let (snapshot, edits) = self.read(buffer, edits);
 246        (FoldMapWriter(self), snapshot, edits)
 247    }
 248
 249    fn check_invariants(&self) {
 250        if cfg!(test) {
 251            assert_eq!(
 252                self.transforms.lock().summary().input.bytes,
 253                self.buffer.lock().len(),
 254                "transform tree does not match buffer's length"
 255            );
 256        }
 257    }
 258
 259    fn sync(
 260        &self,
 261        new_buffer: MultiBufferSnapshot,
 262        buffer_edits: Vec<text::Edit<usize>>,
 263    ) -> Vec<FoldEdit> {
 264        if buffer_edits.is_empty() {
 265            let mut buffer = self.buffer.lock();
 266            if buffer.parse_count() != new_buffer.parse_count()
 267                || buffer.diagnostics_update_count() != new_buffer.diagnostics_update_count()
 268            {
 269                self.version.fetch_add(1, SeqCst);
 270            }
 271            *buffer = new_buffer;
 272            Vec::new()
 273        } else {
 274            let mut buffer_edits_iter = buffer_edits.iter().cloned().peekable();
 275
 276            let mut new_transforms = SumTree::new();
 277            let mut transforms = self.transforms.lock();
 278            let mut cursor = transforms.cursor::<usize>();
 279            cursor.seek(&0, Bias::Right, &());
 280
 281            while let Some(mut edit) = buffer_edits_iter.next() {
 282                new_transforms.push_tree(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 283                edit.new.start -= edit.old.start - cursor.start();
 284                edit.old.start = *cursor.start();
 285
 286                cursor.seek(&edit.old.end, Bias::Right, &());
 287                cursor.next(&());
 288
 289                let mut delta = edit.new.len() as isize - edit.old.len() as isize;
 290                loop {
 291                    edit.old.end = *cursor.start();
 292
 293                    if let Some(next_edit) = buffer_edits_iter.peek() {
 294                        if next_edit.old.start > edit.old.end {
 295                            break;
 296                        }
 297
 298                        let next_edit = buffer_edits_iter.next().unwrap();
 299                        delta += next_edit.new.len() as isize - next_edit.old.len() as isize;
 300
 301                        if next_edit.old.end >= edit.old.end {
 302                            edit.old.end = next_edit.old.end;
 303                            cursor.seek(&edit.old.end, Bias::Right, &());
 304                            cursor.next(&());
 305                        }
 306                    } else {
 307                        break;
 308                    }
 309                }
 310
 311                edit.new.end = ((edit.new.start + edit.old.len()) as isize + delta) as usize;
 312
 313                let anchor = new_buffer.anchor_before(edit.new.start);
 314                let mut folds_cursor = self.folds.cursor::<Fold>();
 315                folds_cursor.seek(&Fold(anchor..Anchor::max()), Bias::Left, &new_buffer);
 316
 317                let mut folds = iter::from_fn({
 318                    let buffer = &new_buffer;
 319                    move || {
 320                        let item = folds_cursor
 321                            .item()
 322                            .map(|f| f.0.start.to_offset(buffer)..f.0.end.to_offset(buffer));
 323                        folds_cursor.next(buffer);
 324                        item
 325                    }
 326                })
 327                .peekable();
 328
 329                while folds.peek().map_or(false, |fold| fold.start < edit.new.end) {
 330                    let mut fold = folds.next().unwrap();
 331                    let sum = new_transforms.summary();
 332
 333                    assert!(fold.start >= sum.input.bytes);
 334
 335                    while folds
 336                        .peek()
 337                        .map_or(false, |next_fold| next_fold.start <= fold.end)
 338                    {
 339                        let next_fold = folds.next().unwrap();
 340                        if next_fold.end > fold.end {
 341                            fold.end = next_fold.end;
 342                        }
 343                    }
 344
 345                    if fold.start > sum.input.bytes {
 346                        let text_summary = new_buffer
 347                            .text_summary_for_range::<TextSummary, _>(sum.input.bytes..fold.start);
 348                        new_transforms.push(
 349                            Transform {
 350                                summary: TransformSummary {
 351                                    output: text_summary.clone(),
 352                                    input: text_summary,
 353                                },
 354                                output_text: None,
 355                            },
 356                            &(),
 357                        );
 358                    }
 359
 360                    if fold.end > fold.start {
 361                        let output_text = "…";
 362                        let chars = output_text.chars().count() as u32;
 363                        let lines = Point::new(0, output_text.len() as u32);
 364                        let lines_utf16 =
 365                            PointUtf16::new(0, output_text.encode_utf16().count() as u32);
 366                        new_transforms.push(
 367                            Transform {
 368                                summary: TransformSummary {
 369                                    output: TextSummary {
 370                                        bytes: output_text.len(),
 371                                        lines,
 372                                        lines_utf16,
 373                                        first_line_chars: chars,
 374                                        last_line_chars: chars,
 375                                        longest_row: 0,
 376                                        longest_row_chars: chars,
 377                                    },
 378                                    input: new_buffer.text_summary_for_range(fold.start..fold.end),
 379                                },
 380                                output_text: Some(output_text),
 381                            },
 382                            &(),
 383                        );
 384                    }
 385                }
 386
 387                let sum = new_transforms.summary();
 388                if sum.input.bytes < edit.new.end {
 389                    let text_summary = new_buffer
 390                        .text_summary_for_range::<TextSummary, _>(sum.input.bytes..edit.new.end);
 391                    new_transforms.push(
 392                        Transform {
 393                            summary: TransformSummary {
 394                                output: text_summary.clone(),
 395                                input: text_summary,
 396                            },
 397                            output_text: None,
 398                        },
 399                        &(),
 400                    );
 401                }
 402            }
 403
 404            new_transforms.push_tree(cursor.suffix(&()), &());
 405            if new_transforms.is_empty() {
 406                let text_summary = new_buffer.text_summary();
 407                new_transforms.push(
 408                    Transform {
 409                        summary: TransformSummary {
 410                            output: text_summary.clone(),
 411                            input: text_summary,
 412                        },
 413                        output_text: None,
 414                    },
 415                    &(),
 416                );
 417            }
 418
 419            drop(cursor);
 420
 421            let mut fold_edits = Vec::with_capacity(buffer_edits.len());
 422            {
 423                let mut old_transforms = transforms.cursor::<(usize, FoldOffset)>();
 424                let mut new_transforms = new_transforms.cursor::<(usize, FoldOffset)>();
 425
 426                for mut edit in buffer_edits {
 427                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 428                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 429                        edit.old.start = old_transforms.start().0;
 430                    }
 431                    let old_start =
 432                        old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0);
 433
 434                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 435                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 436                        old_transforms.next(&());
 437                        edit.old.end = old_transforms.start().0;
 438                    }
 439                    let old_end =
 440                        old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0);
 441
 442                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 443                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 444                        edit.new.start = new_transforms.start().0;
 445                    }
 446                    let new_start =
 447                        new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0);
 448
 449                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 450                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 451                        new_transforms.next(&());
 452                        edit.new.end = new_transforms.start().0;
 453                    }
 454                    let new_end =
 455                        new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0);
 456
 457                    fold_edits.push(FoldEdit {
 458                        old: FoldOffset(old_start)..FoldOffset(old_end),
 459                        new: FoldOffset(new_start)..FoldOffset(new_end),
 460                    });
 461                }
 462
 463                consolidate_fold_edits(&mut fold_edits);
 464            }
 465
 466            *transforms = new_transforms;
 467            *self.buffer.lock() = new_buffer;
 468            self.version.fetch_add(1, SeqCst);
 469            fold_edits
 470        }
 471    }
 472}
 473
 474#[derive(Clone)]
 475pub struct FoldSnapshot {
 476    transforms: SumTree<Transform>,
 477    folds: SumTree<Fold>,
 478    buffer_snapshot: MultiBufferSnapshot,
 479    pub version: usize,
 480}
 481
 482impl FoldSnapshot {
 483    pub fn buffer_snapshot(&self) -> &MultiBufferSnapshot {
 484        &self.buffer_snapshot
 485    }
 486
 487    #[cfg(test)]
 488    pub fn text(&self) -> String {
 489        self.chunks(FoldOffset(0)..self.len(), None)
 490            .map(|c| c.text)
 491            .collect()
 492    }
 493
 494    #[cfg(test)]
 495    pub fn fold_count(&self) -> usize {
 496        self.folds.items(&self.buffer_snapshot).len()
 497    }
 498
 499    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 500        let mut summary = TextSummary::default();
 501
 502        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 503        cursor.seek(&range.start, Bias::Right, &());
 504        if let Some(transform) = cursor.item() {
 505            let start_in_transform = range.start.0 - cursor.start().0 .0;
 506            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 507            if let Some(output_text) = transform.output_text {
 508                summary = TextSummary::from(
 509                    &output_text
 510                        [start_in_transform.column as usize..end_in_transform.column as usize],
 511                );
 512            } else {
 513                let buffer_start = cursor.start().1 + start_in_transform;
 514                let buffer_end = cursor.start().1 + end_in_transform;
 515                summary = self
 516                    .buffer_snapshot
 517                    .text_summary_for_range(buffer_start..buffer_end);
 518            }
 519        }
 520
 521        if range.end > cursor.end(&()).0 {
 522            cursor.next(&());
 523            summary += &cursor
 524                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 525                .output;
 526            if let Some(transform) = cursor.item() {
 527                let end_in_transform = range.end.0 - cursor.start().0 .0;
 528                if let Some(output_text) = transform.output_text {
 529                    summary += TextSummary::from(&output_text[..end_in_transform.column as usize]);
 530                } else {
 531                    let buffer_start = cursor.start().1;
 532                    let buffer_end = cursor.start().1 + end_in_transform;
 533                    summary += self
 534                        .buffer_snapshot
 535                        .text_summary_for_range::<TextSummary, _>(buffer_start..buffer_end);
 536                }
 537            }
 538        }
 539
 540        summary
 541    }
 542
 543    pub fn len(&self) -> FoldOffset {
 544        FoldOffset(self.transforms.summary().output.bytes)
 545    }
 546
 547    #[cfg(test)]
 548    pub fn line_len(&self, row: u32) -> u32 {
 549        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 550        let line_end = if row >= self.max_point().row() {
 551            self.len().0
 552        } else {
 553            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 554        };
 555        (line_end - line_start) as u32
 556    }
 557
 558    pub fn buffer_rows(&self, start_row: u32) -> FoldBufferRows {
 559        if start_row > self.transforms.summary().output.lines.row {
 560            panic!("invalid display row {}", start_row);
 561        }
 562
 563        let fold_point = FoldPoint::new(start_row, 0);
 564        let mut cursor = self.transforms.cursor();
 565        cursor.seek(&fold_point, Bias::Left, &());
 566        FoldBufferRows { fold_point, cursor }
 567    }
 568
 569    pub fn max_point(&self) -> FoldPoint {
 570        FoldPoint(self.transforms.summary().output.lines)
 571    }
 572
 573    #[cfg(test)]
 574    pub fn longest_row(&self) -> u32 {
 575        self.transforms.summary().output.longest_row
 576    }
 577
 578    pub fn folds_in_range<'a, T>(
 579        &'a self,
 580        range: Range<T>,
 581    ) -> impl Iterator<Item = &'a Range<Anchor>>
 582    where
 583        T: ToOffset,
 584    {
 585        let mut folds = intersecting_folds(&self.buffer_snapshot, &self.folds, range, false);
 586        iter::from_fn(move || {
 587            let item = folds.item().map(|f| &f.0);
 588            folds.next(&self.buffer_snapshot);
 589            item
 590        })
 591    }
 592
 593    pub fn intersects_fold<T>(&self, offset: T) -> bool
 594    where
 595        T: ToOffset,
 596    {
 597        let offset = offset.to_offset(&self.buffer_snapshot);
 598        let mut cursor = self.transforms.cursor::<usize>();
 599        cursor.seek(&offset, Bias::Right, &());
 600        cursor.item().map_or(false, |t| t.output_text.is_some())
 601    }
 602
 603    pub fn is_line_folded(&self, output_row: u32) -> bool {
 604        let mut cursor = self.transforms.cursor::<FoldPoint>();
 605        cursor.seek(&FoldPoint::new(output_row, 0), Bias::Right, &());
 606        while let Some(transform) = cursor.item() {
 607            if transform.output_text.is_some() {
 608                return true;
 609            }
 610            if cursor.end(&()).row() == output_row {
 611                cursor.next(&())
 612            } else {
 613                break;
 614            }
 615        }
 616        false
 617    }
 618
 619    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 620        let start = start.to_offset(self);
 621        self.chunks(start..self.len(), None)
 622            .flat_map(|chunk| chunk.text.chars())
 623    }
 624
 625    pub fn chunks<'a>(
 626        &'a self,
 627        range: Range<FoldOffset>,
 628        theme: Option<&'a SyntaxTheme>,
 629    ) -> FoldChunks<'a> {
 630        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 631
 632        transform_cursor.seek(&range.end, Bias::Right, &());
 633        let overshoot = range.end.0 - transform_cursor.start().0 .0;
 634        let buffer_end = transform_cursor.start().1 + overshoot;
 635
 636        transform_cursor.seek(&range.start, Bias::Right, &());
 637        let overshoot = range.start.0 - transform_cursor.start().0 .0;
 638        let buffer_start = transform_cursor.start().1 + overshoot;
 639
 640        FoldChunks {
 641            transform_cursor,
 642            buffer_chunks: self.buffer_snapshot.chunks(buffer_start..buffer_end, theme),
 643            buffer_chunk: None,
 644            buffer_offset: buffer_start,
 645            output_offset: range.start.0,
 646            max_output_offset: range.end.0,
 647        }
 648    }
 649
 650    #[cfg(test)]
 651    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 652        let mut cursor = self.transforms.cursor::<(FoldOffset, usize)>();
 653        cursor.seek(&offset, Bias::Right, &());
 654        if let Some(transform) = cursor.item() {
 655            let transform_start = cursor.start().0 .0;
 656            if transform.output_text.is_some() {
 657                if offset.0 == transform_start || matches!(bias, Bias::Left) {
 658                    FoldOffset(transform_start)
 659                } else {
 660                    FoldOffset(cursor.end(&()).0 .0)
 661                }
 662            } else {
 663                let overshoot = offset.0 - transform_start;
 664                let buffer_offset = cursor.start().1 + overshoot;
 665                let clipped_buffer_offset = self.buffer_snapshot.clip_offset(buffer_offset, bias);
 666                FoldOffset(
 667                    (offset.0 as isize + (clipped_buffer_offset as isize - buffer_offset as isize))
 668                        as usize,
 669                )
 670            }
 671        } else {
 672            FoldOffset(self.transforms.summary().output.bytes)
 673        }
 674    }
 675
 676    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 677        let mut cursor = self.transforms.cursor::<(FoldPoint, Point)>();
 678        cursor.seek(&point, Bias::Right, &());
 679        if let Some(transform) = cursor.item() {
 680            let transform_start = cursor.start().0 .0;
 681            if transform.output_text.is_some() {
 682                if point.0 == transform_start || matches!(bias, Bias::Left) {
 683                    FoldPoint(transform_start)
 684                } else {
 685                    FoldPoint(cursor.end(&()).0 .0)
 686                }
 687            } else {
 688                let overshoot = point.0 - transform_start;
 689                let buffer_position = cursor.start().1 + overshoot;
 690                let clipped_buffer_position =
 691                    self.buffer_snapshot.clip_point(buffer_position, bias);
 692                FoldPoint::new(
 693                    point.row(),
 694                    ((point.column() as i32) + clipped_buffer_position.column as i32
 695                        - buffer_position.column as i32) as u32,
 696                )
 697            }
 698        } else {
 699            FoldPoint(self.transforms.summary().output.lines)
 700        }
 701    }
 702}
 703
 704fn intersecting_folds<'a, T>(
 705    buffer: &'a MultiBufferSnapshot,
 706    folds: &'a SumTree<Fold>,
 707    range: Range<T>,
 708    inclusive: bool,
 709) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 710where
 711    T: ToOffset,
 712{
 713    let start = buffer.anchor_before(range.start.to_offset(buffer));
 714    let end = buffer.anchor_after(range.end.to_offset(buffer));
 715    folds.filter::<_, usize>(
 716        move |summary| {
 717            let start_cmp = start.cmp(&summary.max_end, buffer).unwrap();
 718            let end_cmp = end.cmp(&summary.min_start, buffer).unwrap();
 719
 720            if inclusive {
 721                start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 722            } else {
 723                start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 724            }
 725        },
 726        buffer,
 727    )
 728}
 729
 730fn consolidate_buffer_edits(edits: &mut Vec<text::Edit<usize>>) {
 731    edits.sort_unstable_by(|a, b| {
 732        a.old
 733            .start
 734            .cmp(&b.old.start)
 735            .then_with(|| b.old.end.cmp(&a.old.end))
 736    });
 737
 738    let mut i = 1;
 739    while i < edits.len() {
 740        let edit = edits[i].clone();
 741        let prev_edit = &mut edits[i - 1];
 742        if prev_edit.old.end >= edit.old.start {
 743            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 744            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 745            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 746            edits.remove(i);
 747            continue;
 748        }
 749        i += 1;
 750    }
 751}
 752
 753fn consolidate_fold_edits(edits: &mut Vec<FoldEdit>) {
 754    edits.sort_unstable_by(|a, b| {
 755        a.old
 756            .start
 757            .cmp(&b.old.start)
 758            .then_with(|| b.old.end.cmp(&a.old.end))
 759    });
 760
 761    let mut i = 1;
 762    while i < edits.len() {
 763        let edit = edits[i].clone();
 764        let prev_edit = &mut edits[i - 1];
 765        if prev_edit.old.end >= edit.old.start {
 766            prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 767            prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 768            prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 769            edits.remove(i);
 770            continue;
 771        }
 772        i += 1;
 773    }
 774}
 775
 776#[derive(Clone, Debug, Default, Eq, PartialEq)]
 777struct Transform {
 778    summary: TransformSummary,
 779    output_text: Option<&'static str>,
 780}
 781
 782impl Transform {
 783    fn is_fold(&self) -> bool {
 784        self.output_text.is_some()
 785    }
 786}
 787
 788#[derive(Clone, Debug, Default, Eq, PartialEq)]
 789struct TransformSummary {
 790    output: TextSummary,
 791    input: TextSummary,
 792}
 793
 794impl sum_tree::Item for Transform {
 795    type Summary = TransformSummary;
 796
 797    fn summary(&self) -> Self::Summary {
 798        self.summary.clone()
 799    }
 800}
 801
 802impl sum_tree::Summary for TransformSummary {
 803    type Context = ();
 804
 805    fn add_summary(&mut self, other: &Self, _: &()) {
 806        self.input += &other.input;
 807        self.output += &other.output;
 808    }
 809}
 810
 811#[derive(Clone, Debug)]
 812struct Fold(Range<Anchor>);
 813
 814impl Default for Fold {
 815    fn default() -> Self {
 816        Self(Anchor::min()..Anchor::max())
 817    }
 818}
 819
 820impl sum_tree::Item for Fold {
 821    type Summary = FoldSummary;
 822
 823    fn summary(&self) -> Self::Summary {
 824        FoldSummary {
 825            start: self.0.start.clone(),
 826            end: self.0.end.clone(),
 827            min_start: self.0.start.clone(),
 828            max_end: self.0.end.clone(),
 829            count: 1,
 830        }
 831    }
 832}
 833
 834#[derive(Clone, Debug)]
 835struct FoldSummary {
 836    start: Anchor,
 837    end: Anchor,
 838    min_start: Anchor,
 839    max_end: Anchor,
 840    count: usize,
 841}
 842
 843impl Default for FoldSummary {
 844    fn default() -> Self {
 845        Self {
 846            start: Anchor::min(),
 847            end: Anchor::max(),
 848            min_start: Anchor::max(),
 849            max_end: Anchor::min(),
 850            count: 0,
 851        }
 852    }
 853}
 854
 855impl sum_tree::Summary for FoldSummary {
 856    type Context = MultiBufferSnapshot;
 857
 858    fn add_summary(&mut self, other: &Self, buffer: &MultiBufferSnapshot) {
 859        if other.min_start.cmp(&self.min_start, buffer).unwrap() == Ordering::Less {
 860            self.min_start = other.min_start.clone();
 861        }
 862        if other.max_end.cmp(&self.max_end, buffer).unwrap() == Ordering::Greater {
 863            self.max_end = other.max_end.clone();
 864        }
 865
 866        #[cfg(debug_assertions)]
 867        {
 868            let start_comparison = self.start.cmp(&other.start, buffer).unwrap();
 869            assert!(start_comparison <= Ordering::Equal);
 870            if start_comparison == Ordering::Equal {
 871                assert!(self.end.cmp(&other.end, buffer).unwrap() >= Ordering::Equal);
 872            }
 873        }
 874
 875        self.start = other.start.clone();
 876        self.end = other.end.clone();
 877        self.count += other.count;
 878    }
 879}
 880
 881impl<'a> sum_tree::Dimension<'a, FoldSummary> for Fold {
 882    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 883        self.0.start = summary.start.clone();
 884        self.0.end = summary.end.clone();
 885    }
 886}
 887
 888impl<'a> sum_tree::SeekTarget<'a, FoldSummary, Fold> for Fold {
 889    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
 890        self.0.cmp(&other.0, buffer).unwrap()
 891    }
 892}
 893
 894impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
 895    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
 896        *self += summary.count;
 897    }
 898}
 899
 900pub struct FoldBufferRows<'a> {
 901    cursor: Cursor<'a, Transform, (FoldPoint, Point)>,
 902    fold_point: FoldPoint,
 903}
 904
 905impl<'a> Iterator for FoldBufferRows<'a> {
 906    type Item = u32;
 907
 908    fn next(&mut self) -> Option<Self::Item> {
 909        while self.fold_point > self.cursor.end(&()).0 {
 910            self.cursor.next(&());
 911            if self.cursor.item().is_none() {
 912                // TODO: Return a bool from next?
 913                break;
 914            }
 915        }
 916
 917        if self.cursor.item().is_some() {
 918            let overshoot = self.fold_point.0 - self.cursor.start().0 .0;
 919            let buffer_point = self.cursor.start().1 + overshoot;
 920            *self.fold_point.row_mut() += 1;
 921            Some(buffer_point.row)
 922        } else {
 923            None
 924        }
 925    }
 926}
 927
 928pub struct FoldChunks<'a> {
 929    transform_cursor: Cursor<'a, Transform, (FoldOffset, usize)>,
 930    buffer_chunks: MultiBufferChunks<'a>,
 931    buffer_chunk: Option<(usize, Chunk<'a>)>,
 932    buffer_offset: usize,
 933    output_offset: usize,
 934    max_output_offset: usize,
 935}
 936
 937impl<'a> Iterator for FoldChunks<'a> {
 938    type Item = Chunk<'a>;
 939
 940    fn next(&mut self) -> Option<Self::Item> {
 941        if self.output_offset >= self.max_output_offset {
 942            return None;
 943        }
 944
 945        let transform = if let Some(item) = self.transform_cursor.item() {
 946            item
 947        } else {
 948            return None;
 949        };
 950
 951        // If we're in a fold, then return the fold's display text and
 952        // advance the transform and buffer cursors to the end of the fold.
 953        if let Some(output_text) = transform.output_text {
 954            self.buffer_chunk.take();
 955            self.buffer_offset += transform.summary.input.bytes;
 956            self.buffer_chunks.seek(self.buffer_offset);
 957
 958            while self.buffer_offset >= self.transform_cursor.end(&()).1
 959                && self.transform_cursor.item().is_some()
 960            {
 961                self.transform_cursor.next(&());
 962            }
 963
 964            self.output_offset += output_text.len();
 965            return Some(Chunk {
 966                text: output_text,
 967                highlight_style: None,
 968                diagnostic: None,
 969            });
 970        }
 971
 972        // Retrieve a chunk from the current location in the buffer.
 973        if self.buffer_chunk.is_none() {
 974            let chunk_offset = self.buffer_chunks.offset();
 975            self.buffer_chunk = self.buffer_chunks.next().map(|chunk| (chunk_offset, chunk));
 976        }
 977
 978        // Otherwise, take a chunk from the buffer's text.
 979        if let Some((chunk_offset, mut chunk)) = self.buffer_chunk {
 980            let offset_in_chunk = self.buffer_offset - chunk_offset;
 981            chunk.text = &chunk.text[offset_in_chunk..];
 982
 983            // Truncate the chunk so that it ends at the next fold.
 984            let region_end = self.transform_cursor.end(&()).1 - self.buffer_offset;
 985            if chunk.text.len() >= region_end {
 986                chunk.text = &chunk.text[0..region_end];
 987                self.transform_cursor.next(&());
 988            } else {
 989                self.buffer_chunk.take();
 990            }
 991
 992            self.buffer_offset += chunk.text.len();
 993            self.output_offset += chunk.text.len();
 994            return Some(chunk);
 995        }
 996
 997        None
 998    }
 999}
1000
1001impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
1002    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1003        self.0 += &summary.output.lines;
1004    }
1005}
1006
1007#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1008pub struct FoldOffset(pub usize);
1009
1010impl FoldOffset {
1011    pub fn to_point(&self, snapshot: &FoldSnapshot) -> FoldPoint {
1012        let mut cursor = snapshot
1013            .transforms
1014            .cursor::<(FoldOffset, TransformSummary)>();
1015        cursor.seek(self, Bias::Right, &());
1016        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1017            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1018        } else {
1019            let buffer_offset = cursor.start().1.input.bytes + self.0 - cursor.start().0 .0;
1020            let buffer_point = snapshot.buffer_snapshot.offset_to_point(buffer_offset);
1021            buffer_point - cursor.start().1.input.lines
1022        };
1023        FoldPoint(cursor.start().1.output.lines + overshoot)
1024    }
1025}
1026
1027impl Sub for FoldOffset {
1028    type Output = Self;
1029
1030    fn sub(self, rhs: Self) -> Self::Output {
1031        Self(self.0 - rhs.0)
1032    }
1033}
1034
1035impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1036    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1037        self.0 += &summary.output.bytes;
1038    }
1039}
1040
1041impl<'a> sum_tree::Dimension<'a, TransformSummary> for Point {
1042    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1043        *self += &summary.input.lines;
1044    }
1045}
1046
1047impl<'a> sum_tree::Dimension<'a, TransformSummary> for usize {
1048    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1049        *self += &summary.input.bytes;
1050    }
1051}
1052
1053pub type FoldEdit = Edit<FoldOffset>;
1054
1055#[cfg(test)]
1056mod tests {
1057    use super::*;
1058    use crate::{MultiBuffer, ToPoint};
1059    use rand::prelude::*;
1060    use std::{env, mem};
1061    use text::RandomCharIter;
1062    use util::test::sample_text;
1063    use Bias::{Left, Right};
1064
1065    #[gpui::test]
1066    fn test_basic_folds(cx: &mut gpui::MutableAppContext) {
1067        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1068        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1069        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1070        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1071
1072        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1073        let (snapshot2, edits) = writer.fold(vec![
1074            Point::new(0, 2)..Point::new(2, 2),
1075            Point::new(2, 4)..Point::new(4, 1),
1076        ]);
1077        assert_eq!(snapshot2.text(), "aa…cc…eeeee");
1078        assert_eq!(
1079            edits,
1080            &[
1081                FoldEdit {
1082                    old: FoldOffset(2)..FoldOffset(16),
1083                    new: FoldOffset(2)..FoldOffset(5),
1084                },
1085                FoldEdit {
1086                    old: FoldOffset(18)..FoldOffset(29),
1087                    new: FoldOffset(7)..FoldOffset(10)
1088                },
1089            ]
1090        );
1091
1092        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1093            buffer.edit(
1094                vec![
1095                    Point::new(0, 0)..Point::new(0, 1),
1096                    Point::new(2, 3)..Point::new(2, 3),
1097                ],
1098                "123",
1099                cx,
1100            );
1101            buffer.snapshot(cx)
1102        });
1103        let (snapshot3, edits) =
1104            map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1105        assert_eq!(snapshot3.text(), "123a…c123c…eeeee");
1106        assert_eq!(
1107            edits,
1108            &[
1109                FoldEdit {
1110                    old: FoldOffset(0)..FoldOffset(1),
1111                    new: FoldOffset(0)..FoldOffset(3),
1112                },
1113                FoldEdit {
1114                    old: FoldOffset(6)..FoldOffset(6),
1115                    new: FoldOffset(8)..FoldOffset(11),
1116                },
1117            ]
1118        );
1119
1120        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1121            buffer.edit(vec![Point::new(2, 6)..Point::new(4, 3)], "456", cx);
1122            buffer.snapshot(cx)
1123        });
1124        let (snapshot4, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1125        assert_eq!(snapshot4.text(), "123a…c123456eee");
1126
1127        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1128        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 5)));
1129        let (snapshot5, _) = map.read(buffer_snapshot.clone(), vec![]);
1130        assert_eq!(snapshot5.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1131    }
1132
1133    #[gpui::test]
1134    fn test_adjacent_folds(cx: &mut gpui::MutableAppContext) {
1135        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1136        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1137        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1138
1139        {
1140            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1141
1142            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1143            writer.fold(vec![5..8]);
1144            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1145            assert_eq!(snapshot.text(), "abcde…ijkl");
1146
1147            // Create an fold adjacent to the start of the first fold.
1148            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1149            writer.fold(vec![0..1, 2..5]);
1150            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1151            assert_eq!(snapshot.text(), "…b…ijkl");
1152
1153            // Create an fold adjacent to the end of the first fold.
1154            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1155            writer.fold(vec![11..11, 8..10]);
1156            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1157            assert_eq!(snapshot.text(), "…b…kl");
1158        }
1159
1160        {
1161            let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1162
1163            // Create two adjacent folds.
1164            let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1165            writer.fold(vec![0..2, 2..5]);
1166            let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1167            assert_eq!(snapshot.text(), "…fghijkl");
1168
1169            // Edit within one of the folds.
1170            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1171                buffer.edit(vec![0..1], "12345", cx);
1172                buffer.snapshot(cx)
1173            });
1174            let (snapshot, _) =
1175                map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1176            assert_eq!(snapshot.text(), "12345…fghijkl");
1177        }
1178    }
1179
1180    #[gpui::test]
1181    fn test_overlapping_folds(cx: &mut gpui::MutableAppContext) {
1182        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1183        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1184        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1185        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1186        writer.fold(vec![
1187            Point::new(0, 2)..Point::new(2, 2),
1188            Point::new(0, 4)..Point::new(1, 0),
1189            Point::new(1, 2)..Point::new(3, 2),
1190            Point::new(3, 1)..Point::new(4, 1),
1191        ]);
1192        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1193        assert_eq!(snapshot.text(), "aa…eeeee");
1194    }
1195
1196    #[gpui::test]
1197    fn test_merging_folds_via_edit(cx: &mut gpui::MutableAppContext) {
1198        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1199        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1200        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1201        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1202
1203        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1204        writer.fold(vec![
1205            Point::new(0, 2)..Point::new(2, 2),
1206            Point::new(3, 1)..Point::new(4, 1),
1207        ]);
1208        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1209        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee");
1210
1211        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1212            buffer.edit(Some(Point::new(2, 2)..Point::new(3, 1)), "", cx);
1213            buffer.snapshot(cx)
1214        });
1215        let (snapshot, _) = map.read(buffer_snapshot.clone(), subscription.consume().into_inner());
1216        assert_eq!(snapshot.text(), "aa…eeeee");
1217    }
1218
1219    #[gpui::test]
1220    fn test_folds_in_range(cx: &mut gpui::MutableAppContext) {
1221        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1222        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1223        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1224
1225        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1226        writer.fold(vec![
1227            Point::new(0, 2)..Point::new(2, 2),
1228            Point::new(0, 4)..Point::new(1, 0),
1229            Point::new(1, 2)..Point::new(3, 2),
1230            Point::new(3, 1)..Point::new(4, 1),
1231        ]);
1232        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1233        let fold_ranges = snapshot
1234            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1235            .map(|fold| fold.start.to_point(&buffer_snapshot)..fold.end.to_point(&buffer_snapshot))
1236            .collect::<Vec<_>>();
1237        assert_eq!(
1238            fold_ranges,
1239            vec![
1240                Point::new(0, 2)..Point::new(2, 2),
1241                Point::new(1, 2)..Point::new(3, 2)
1242            ]
1243        );
1244    }
1245
1246    #[gpui::test(iterations = 100)]
1247    fn test_random_folds(cx: &mut gpui::MutableAppContext, mut rng: StdRng) {
1248        let operations = env::var("OPERATIONS")
1249            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1250            .unwrap_or(10);
1251
1252        let len = rng.gen_range(0..10);
1253        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1254        let buffer = if rng.gen() {
1255            MultiBuffer::build_simple(&text, cx)
1256        } else {
1257            MultiBuffer::build_random(rng.gen_range(1..=5), &mut rng, cx)
1258        };
1259        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1260        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1261
1262        let (mut initial_snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1263        let mut snapshot_edits = Vec::new();
1264
1265        for _ in 0..operations {
1266            log::info!("text: {:?}", buffer_snapshot.text());
1267            let mut buffer_edits = Vec::new();
1268            match rng.gen_range(0..=100) {
1269                0..=59 => {
1270                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1271                }
1272                _ => buffer.update(cx, |buffer, cx| {
1273                    let subscription = buffer.subscribe();
1274                    let edit_count = rng.gen_range(1..=5);
1275                    buffer.randomly_edit(&mut rng, edit_count, cx);
1276                    buffer_snapshot = buffer.snapshot(cx);
1277                    let edits = subscription.consume().into_inner();
1278                    log::info!("editing {:?}", edits);
1279                    buffer_edits.extend(edits);
1280                }),
1281            };
1282
1283            let (snapshot, edits) = map.read(buffer_snapshot.clone(), buffer_edits);
1284            snapshot_edits.push((snapshot.clone(), edits));
1285
1286            let mut expected_text: String = buffer_snapshot.text().to_string();
1287            let mut expected_buffer_rows = Vec::new();
1288            let mut next_row = buffer_snapshot.max_point().row;
1289            for fold_range in map.merged_fold_ranges().into_iter().rev() {
1290                let fold_start = buffer_snapshot.offset_to_point(fold_range.start);
1291                let fold_end = buffer_snapshot.offset_to_point(fold_range.end);
1292                expected_buffer_rows.extend((fold_end.row + 1..=next_row).rev());
1293                next_row = fold_start.row;
1294
1295                expected_text.replace_range(fold_range.start..fold_range.end, "…");
1296            }
1297            expected_buffer_rows.extend((0..=next_row).rev());
1298            expected_buffer_rows.reverse();
1299
1300            assert_eq!(snapshot.text(), expected_text);
1301
1302            for (output_row, line) in expected_text.lines().enumerate() {
1303                let line_len = snapshot.line_len(output_row as u32);
1304                assert_eq!(line_len, line.len() as u32);
1305            }
1306
1307            let longest_row = snapshot.longest_row();
1308            let longest_char_column = expected_text
1309                .split('\n')
1310                .nth(longest_row as usize)
1311                .unwrap()
1312                .chars()
1313                .count();
1314            let mut fold_point = FoldPoint::new(0, 0);
1315            let mut fold_offset = FoldOffset(0);
1316            let mut char_column = 0;
1317            for c in expected_text.chars() {
1318                let buffer_point = fold_point.to_buffer_point(&snapshot);
1319                let buffer_offset = buffer_point.to_offset(&buffer_snapshot);
1320                assert_eq!(
1321                    buffer_point.to_fold_point(&snapshot, Right),
1322                    fold_point,
1323                    "{:?} -> fold point",
1324                    buffer_point,
1325                );
1326                assert_eq!(
1327                    fold_point.to_buffer_offset(&snapshot),
1328                    buffer_offset,
1329                    "fold_point.to_buffer_offset({:?})",
1330                    fold_point,
1331                );
1332                assert_eq!(
1333                    fold_point.to_offset(&snapshot),
1334                    fold_offset,
1335                    "fold_point.to_offset({:?})",
1336                    fold_point,
1337                );
1338
1339                if c == '\n' {
1340                    *fold_point.row_mut() += 1;
1341                    *fold_point.column_mut() = 0;
1342                    char_column = 0;
1343                } else {
1344                    *fold_point.column_mut() += c.len_utf8() as u32;
1345                    char_column += 1;
1346                }
1347                fold_offset.0 += c.len_utf8();
1348                if char_column > longest_char_column {
1349                    panic!(
1350                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1351                        longest_row,
1352                        longest_char_column,
1353                        fold_point.row(),
1354                        char_column
1355                    );
1356                }
1357            }
1358
1359            for _ in 0..5 {
1360                let mut start = snapshot
1361                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1362                let mut end = snapshot
1363                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1364                if start > end {
1365                    mem::swap(&mut start, &mut end);
1366                }
1367
1368                let text = &expected_text[start.0..end.0];
1369                log::info!("slicing {:?}..{:?} (text: {:?})", start, end, text);
1370                assert_eq!(
1371                    snapshot
1372                        .chunks(start..end, None)
1373                        .map(|c| c.text)
1374                        .collect::<String>(),
1375                    text,
1376                );
1377            }
1378
1379            for (idx, buffer_row) in expected_buffer_rows.iter().enumerate() {
1380                let fold_row = Point::new(*buffer_row, 0)
1381                    .to_fold_point(&snapshot, Right)
1382                    .row();
1383                assert_eq!(
1384                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1385                    expected_buffer_rows[idx..],
1386                );
1387            }
1388
1389            for fold_range in map.merged_fold_ranges() {
1390                let fold_point = fold_range
1391                    .start
1392                    .to_point(&buffer_snapshot)
1393                    .to_fold_point(&snapshot, Right);
1394                assert!(snapshot.is_line_folded(fold_point.row()));
1395            }
1396
1397            for _ in 0..5 {
1398                let end =
1399                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1400                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1401                let expected_folds = map
1402                    .folds
1403                    .items(&buffer_snapshot)
1404                    .into_iter()
1405                    .filter(|fold| {
1406                        let start = buffer_snapshot.anchor_before(start);
1407                        let end = buffer_snapshot.anchor_after(end);
1408                        start.cmp(&fold.0.end, &buffer_snapshot).unwrap() == Ordering::Less
1409                            && end.cmp(&fold.0.start, &buffer_snapshot).unwrap()
1410                                == Ordering::Greater
1411                    })
1412                    .map(|fold| fold.0)
1413                    .collect::<Vec<_>>();
1414
1415                assert_eq!(
1416                    snapshot
1417                        .folds_in_range(start..end)
1418                        .cloned()
1419                        .collect::<Vec<_>>(),
1420                    expected_folds
1421                );
1422            }
1423
1424            let text = snapshot.text();
1425            for _ in 0..5 {
1426                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1427                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1428                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1429                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1430                let mut start =
1431                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1432                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1433                if start > end {
1434                    mem::swap(&mut start, &mut end);
1435                }
1436
1437                let lines = start..end;
1438                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1439                assert_eq!(
1440                    snapshot.text_summary_for_range(lines),
1441                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1442                )
1443            }
1444
1445            let mut text = initial_snapshot.text();
1446            for (snapshot, edits) in snapshot_edits.drain(..) {
1447                let new_text = snapshot.text();
1448                for edit in edits {
1449                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1450                    let new_bytes = edit.new.start.0..edit.new.end.0;
1451                    text.replace_range(old_bytes, &new_text[new_bytes]);
1452                }
1453
1454                assert_eq!(text, new_text);
1455                initial_snapshot = snapshot;
1456            }
1457        }
1458    }
1459
1460    #[gpui::test]
1461    fn test_buffer_rows(cx: &mut gpui::MutableAppContext) {
1462        let text = sample_text(6, 6, 'a') + "\n";
1463        let buffer = MultiBuffer::build_simple(&text, cx);
1464
1465        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1466        let mut map = FoldMap::new(buffer_snapshot.clone()).0;
1467
1468        let (mut writer, _, _) = map.write(buffer_snapshot.clone(), vec![]);
1469        writer.fold(vec![
1470            Point::new(0, 2)..Point::new(2, 2),
1471            Point::new(3, 1)..Point::new(4, 1),
1472        ]);
1473
1474        let (snapshot, _) = map.read(buffer_snapshot.clone(), vec![]);
1475        assert_eq!(snapshot.text(), "aa…cccc\nd…eeeee\nffffff\n");
1476        assert_eq!(snapshot.buffer_rows(0).collect::<Vec<_>>(), [0, 3, 5, 6]);
1477        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [6]);
1478    }
1479
1480    impl FoldMap {
1481        fn merged_fold_ranges(&self) -> Vec<Range<usize>> {
1482            let buffer = self.buffer.lock().clone();
1483            let mut folds = self.folds.items(&buffer);
1484            // Ensure sorting doesn't change how folds get merged and displayed.
1485            folds.sort_by(|a, b| a.0.cmp(&b.0, &buffer).unwrap());
1486            let mut fold_ranges = folds
1487                .iter()
1488                .map(|fold| fold.0.start.to_offset(&buffer)..fold.0.end.to_offset(&buffer))
1489                .peekable();
1490
1491            let mut merged_ranges = Vec::new();
1492            while let Some(mut fold_range) = fold_ranges.next() {
1493                while let Some(next_range) = fold_ranges.peek() {
1494                    if fold_range.end >= next_range.start {
1495                        if next_range.end > fold_range.end {
1496                            fold_range.end = next_range.end;
1497                        }
1498                        fold_ranges.next();
1499                    } else {
1500                        break;
1501                    }
1502                }
1503                if fold_range.end > fold_range.start {
1504                    merged_ranges.push(fold_range);
1505                }
1506            }
1507            merged_ranges
1508        }
1509
1510        pub fn randomly_mutate(
1511            &mut self,
1512            rng: &mut impl Rng,
1513        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1514            let mut snapshot_edits = Vec::new();
1515            match rng.gen_range(0..=100) {
1516                0..=39 if !self.folds.is_empty() => {
1517                    let buffer = self.buffer.lock().clone();
1518                    let mut to_unfold = Vec::new();
1519                    for _ in 0..rng.gen_range(1..=3) {
1520                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1521                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1522                        to_unfold.push(start..end);
1523                    }
1524                    log::info!("unfolding {:?}", to_unfold);
1525                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1526                    snapshot_edits.push((snapshot, edits));
1527                    let (snapshot, edits) = writer.fold(to_unfold);
1528                    snapshot_edits.push((snapshot, edits));
1529                }
1530                _ => {
1531                    let buffer = self.buffer.lock().clone();
1532                    let mut to_fold = Vec::new();
1533                    for _ in 0..rng.gen_range(1..=2) {
1534                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1535                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1536                        to_fold.push(start..end);
1537                    }
1538                    log::info!("folding {:?}", to_fold);
1539                    let (mut writer, snapshot, edits) = self.write(buffer, vec![]);
1540                    snapshot_edits.push((snapshot, edits));
1541                    let (snapshot, edits) = writer.fold(to_fold);
1542                    snapshot_edits.push((snapshot, edits));
1543                }
1544            }
1545            snapshot_edits
1546        }
1547    }
1548}