fold_map.rs

   1use super::{
   2    inlay_map::{InlayBufferRows, InlayChunks, InlayEdit, InlayOffset, InlayPoint, InlaySnapshot},
   3    Highlights,
   4};
   5use gpui::{AnyElement, ElementId, WindowContext};
   6use language::{Chunk, ChunkRenderer, Edit, Point, TextSummary};
   7use multi_buffer::{Anchor, AnchorRangeExt, MultiBufferRow, MultiBufferSnapshot, ToOffset};
   8use std::{
   9    cmp::{self, Ordering},
  10    fmt, iter,
  11    ops::{Add, AddAssign, Deref, DerefMut, Range, Sub},
  12    sync::Arc,
  13};
  14use sum_tree::{Bias, Cursor, FilterCursor, SumTree, Summary};
  15use util::post_inc;
  16
  17#[derive(Clone)]
  18pub struct FoldPlaceholder {
  19    /// Creates an element to represent this fold's placeholder.
  20    pub render: Arc<dyn Send + Sync + Fn(FoldId, Range<Anchor>, &mut WindowContext) -> AnyElement>,
  21    /// If true, the element is constrained to the shaped width of an ellipsis.
  22    pub constrain_width: bool,
  23    /// If true, merges the fold with an adjacent one.
  24    pub merge_adjacent: bool,
  25}
  26
  27impl FoldPlaceholder {
  28    #[cfg(any(test, feature = "test-support"))]
  29    pub fn test() -> Self {
  30        use gpui::IntoElement;
  31
  32        Self {
  33            render: Arc::new(|_id, _range, _cx| gpui::Empty.into_any_element()),
  34            constrain_width: true,
  35            merge_adjacent: true,
  36        }
  37    }
  38}
  39
  40impl fmt::Debug for FoldPlaceholder {
  41    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  42        f.debug_struct("FoldPlaceholder")
  43            .field("constrain_width", &self.constrain_width)
  44            .finish()
  45    }
  46}
  47
  48impl Eq for FoldPlaceholder {}
  49
  50impl PartialEq for FoldPlaceholder {
  51    fn eq(&self, other: &Self) -> bool {
  52        Arc::ptr_eq(&self.render, &other.render) && self.constrain_width == other.constrain_width
  53    }
  54}
  55
  56#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  57pub struct FoldPoint(pub Point);
  58
  59impl FoldPoint {
  60    pub fn new(row: u32, column: u32) -> Self {
  61        Self(Point::new(row, column))
  62    }
  63
  64    pub fn row(self) -> u32 {
  65        self.0.row
  66    }
  67
  68    pub fn column(self) -> u32 {
  69        self.0.column
  70    }
  71
  72    pub fn row_mut(&mut self) -> &mut u32 {
  73        &mut self.0.row
  74    }
  75
  76    #[cfg(test)]
  77    pub fn column_mut(&mut self) -> &mut u32 {
  78        &mut self.0.column
  79    }
  80
  81    pub fn to_inlay_point(self, snapshot: &FoldSnapshot) -> InlayPoint {
  82        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
  83        cursor.seek(&self, Bias::Right, &());
  84        let overshoot = self.0 - cursor.start().0 .0;
  85        InlayPoint(cursor.start().1 .0 + overshoot)
  86    }
  87
  88    pub fn to_offset(self, snapshot: &FoldSnapshot) -> FoldOffset {
  89        let mut cursor = snapshot
  90            .transforms
  91            .cursor::<(FoldPoint, TransformSummary)>(&());
  92        cursor.seek(&self, Bias::Right, &());
  93        let overshoot = self.0 - cursor.start().1.output.lines;
  94        let mut offset = cursor.start().1.output.len;
  95        if !overshoot.is_zero() {
  96            let transform = cursor.item().expect("display point out of range");
  97            assert!(transform.placeholder.is_none());
  98            let end_inlay_offset = snapshot
  99                .inlay_snapshot
 100                .to_offset(InlayPoint(cursor.start().1.input.lines + overshoot));
 101            offset += end_inlay_offset.0 - cursor.start().1.input.len;
 102        }
 103        FoldOffset(offset)
 104    }
 105}
 106
 107impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
 108    fn zero(_cx: &()) -> Self {
 109        Default::default()
 110    }
 111
 112    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
 113        self.0 += &summary.output.lines;
 114    }
 115}
 116
 117pub(crate) struct FoldMapWriter<'a>(&'a mut FoldMap);
 118
 119impl<'a> FoldMapWriter<'a> {
 120    pub(crate) fn fold<T: ToOffset>(
 121        &mut self,
 122        ranges: impl IntoIterator<Item = (Range<T>, FoldPlaceholder)>,
 123    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 124        let mut edits = Vec::new();
 125        let mut folds = Vec::new();
 126        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 127        for (range, fold_text) in ranges.into_iter() {
 128            let buffer = &snapshot.buffer;
 129            let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 130
 131            // Ignore any empty ranges.
 132            if range.start == range.end {
 133                continue;
 134            }
 135
 136            // For now, ignore any ranges that span an excerpt boundary.
 137            let fold_range =
 138                FoldRange(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 139            if fold_range.0.start.excerpt_id != fold_range.0.end.excerpt_id {
 140                continue;
 141            }
 142
 143            folds.push(Fold {
 144                id: FoldId(post_inc(&mut self.0.next_fold_id.0)),
 145                range: fold_range,
 146                placeholder: fold_text,
 147            });
 148
 149            let inlay_range =
 150                snapshot.to_inlay_offset(range.start)..snapshot.to_inlay_offset(range.end);
 151            edits.push(InlayEdit {
 152                old: inlay_range.clone(),
 153                new: inlay_range,
 154            });
 155        }
 156
 157        let buffer = &snapshot.buffer;
 158        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(&a.range, &b.range, buffer));
 159
 160        self.0.snapshot.folds = {
 161            let mut new_tree = SumTree::new(buffer);
 162            let mut cursor = self.0.snapshot.folds.cursor::<FoldRange>(buffer);
 163            for fold in folds {
 164                new_tree.append(cursor.slice(&fold.range, Bias::Right, buffer), buffer);
 165                new_tree.push(fold, buffer);
 166            }
 167            new_tree.append(cursor.suffix(buffer), buffer);
 168            new_tree
 169        };
 170
 171        let edits = consolidate_inlay_edits(edits);
 172        let edits = self.0.sync(snapshot.clone(), edits);
 173        (self.0.snapshot.clone(), edits)
 174    }
 175
 176    pub(crate) fn unfold<T: ToOffset>(
 177        &mut self,
 178        ranges: impl IntoIterator<Item = Range<T>>,
 179        inclusive: bool,
 180    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 181        let mut edits = Vec::new();
 182        let mut fold_ixs_to_delete = Vec::new();
 183        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 184        let buffer = &snapshot.buffer;
 185        for range in ranges.into_iter() {
 186            // Remove intersecting folds and add their ranges to edits that are passed to sync.
 187            let mut folds_cursor =
 188                intersecting_folds(&snapshot, &self.0.snapshot.folds, range, inclusive);
 189            while let Some(fold) = folds_cursor.item() {
 190                let offset_range =
 191                    fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer);
 192                if offset_range.end > offset_range.start {
 193                    let inlay_range = snapshot.to_inlay_offset(offset_range.start)
 194                        ..snapshot.to_inlay_offset(offset_range.end);
 195                    edits.push(InlayEdit {
 196                        old: inlay_range.clone(),
 197                        new: inlay_range,
 198                    });
 199                }
 200                fold_ixs_to_delete.push(*folds_cursor.start());
 201                folds_cursor.next(buffer);
 202            }
 203        }
 204
 205        fold_ixs_to_delete.sort_unstable();
 206        fold_ixs_to_delete.dedup();
 207
 208        self.0.snapshot.folds = {
 209            let mut cursor = self.0.snapshot.folds.cursor::<usize>(buffer);
 210            let mut folds = SumTree::new(buffer);
 211            for fold_ix in fold_ixs_to_delete {
 212                folds.append(cursor.slice(&fold_ix, Bias::Right, buffer), buffer);
 213                cursor.next(buffer);
 214            }
 215            folds.append(cursor.suffix(buffer), buffer);
 216            folds
 217        };
 218
 219        let edits = consolidate_inlay_edits(edits);
 220        let edits = self.0.sync(snapshot.clone(), edits);
 221        (self.0.snapshot.clone(), edits)
 222    }
 223}
 224
 225/// Decides where the fold indicators should be; also tracks parts of a source file that are currently folded.
 226///
 227/// See the [`display_map` module documentation](crate::display_map) for more information.
 228pub(crate) struct FoldMap {
 229    snapshot: FoldSnapshot,
 230    next_fold_id: FoldId,
 231}
 232
 233impl FoldMap {
 234    pub(crate) fn new(inlay_snapshot: InlaySnapshot) -> (Self, FoldSnapshot) {
 235        let this = Self {
 236            snapshot: FoldSnapshot {
 237                folds: SumTree::new(&inlay_snapshot.buffer),
 238                transforms: SumTree::from_item(
 239                    Transform {
 240                        summary: TransformSummary {
 241                            input: inlay_snapshot.text_summary(),
 242                            output: inlay_snapshot.text_summary(),
 243                        },
 244                        placeholder: None,
 245                    },
 246                    &(),
 247                ),
 248                inlay_snapshot: inlay_snapshot.clone(),
 249                version: 0,
 250            },
 251            next_fold_id: FoldId::default(),
 252        };
 253        let snapshot = this.snapshot.clone();
 254        (this, snapshot)
 255    }
 256
 257    pub fn read(
 258        &mut self,
 259        inlay_snapshot: InlaySnapshot,
 260        edits: Vec<InlayEdit>,
 261    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 262        let edits = self.sync(inlay_snapshot, edits);
 263        self.check_invariants();
 264        (self.snapshot.clone(), edits)
 265    }
 266
 267    pub fn write(
 268        &mut self,
 269        inlay_snapshot: InlaySnapshot,
 270        edits: Vec<InlayEdit>,
 271    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 272        let (snapshot, edits) = self.read(inlay_snapshot, edits);
 273        (FoldMapWriter(self), snapshot, edits)
 274    }
 275
 276    fn check_invariants(&self) {
 277        if cfg!(test) {
 278            assert_eq!(
 279                self.snapshot.transforms.summary().input.len,
 280                self.snapshot.inlay_snapshot.len().0,
 281                "transform tree does not match inlay snapshot's length"
 282            );
 283
 284            let mut prev_transform_isomorphic = false;
 285            for transform in self.snapshot.transforms.iter() {
 286                if !transform.is_fold() && prev_transform_isomorphic {
 287                    panic!(
 288                        "found adjacent isomorphic transforms: {:?}",
 289                        self.snapshot.transforms.items(&())
 290                    );
 291                }
 292                prev_transform_isomorphic = !transform.is_fold();
 293            }
 294
 295            let mut folds = self.snapshot.folds.iter().peekable();
 296            while let Some(fold) = folds.next() {
 297                if let Some(next_fold) = folds.peek() {
 298                    let comparison = fold
 299                        .range
 300                        .cmp(&next_fold.range, &self.snapshot.inlay_snapshot.buffer);
 301                    assert!(comparison.is_le());
 302                }
 303            }
 304        }
 305    }
 306
 307    fn sync(
 308        &mut self,
 309        inlay_snapshot: InlaySnapshot,
 310        inlay_edits: Vec<InlayEdit>,
 311    ) -> Vec<FoldEdit> {
 312        if inlay_edits.is_empty() {
 313            if self.snapshot.inlay_snapshot.version != inlay_snapshot.version {
 314                self.snapshot.version += 1;
 315            }
 316            self.snapshot.inlay_snapshot = inlay_snapshot;
 317            Vec::new()
 318        } else {
 319            let mut inlay_edits_iter = inlay_edits.iter().cloned().peekable();
 320
 321            let mut new_transforms = SumTree::<Transform>::default();
 322            let mut cursor = self.snapshot.transforms.cursor::<InlayOffset>(&());
 323            cursor.seek(&InlayOffset(0), Bias::Right, &());
 324
 325            while let Some(mut edit) = inlay_edits_iter.next() {
 326                if let Some(item) = cursor.item() {
 327                    if !item.is_fold() {
 328                        new_transforms.update_last(
 329                            |transform| {
 330                                if !transform.is_fold() {
 331                                    transform.summary.add_summary(&item.summary, &());
 332                                    cursor.next(&());
 333                                }
 334                            },
 335                            &(),
 336                        );
 337                    }
 338                }
 339                new_transforms.append(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 340                edit.new.start -= edit.old.start - *cursor.start();
 341                edit.old.start = *cursor.start();
 342
 343                cursor.seek(&edit.old.end, Bias::Right, &());
 344                cursor.next(&());
 345
 346                let mut delta = edit.new_len().0 as isize - edit.old_len().0 as isize;
 347                loop {
 348                    edit.old.end = *cursor.start();
 349
 350                    if let Some(next_edit) = inlay_edits_iter.peek() {
 351                        if next_edit.old.start > edit.old.end {
 352                            break;
 353                        }
 354
 355                        let next_edit = inlay_edits_iter.next().unwrap();
 356                        delta += next_edit.new_len().0 as isize - next_edit.old_len().0 as isize;
 357
 358                        if next_edit.old.end >= edit.old.end {
 359                            edit.old.end = next_edit.old.end;
 360                            cursor.seek(&edit.old.end, Bias::Right, &());
 361                            cursor.next(&());
 362                        }
 363                    } else {
 364                        break;
 365                    }
 366                }
 367
 368                edit.new.end =
 369                    InlayOffset(((edit.new.start + edit.old_len()).0 as isize + delta) as usize);
 370
 371                let anchor = inlay_snapshot
 372                    .buffer
 373                    .anchor_before(inlay_snapshot.to_buffer_offset(edit.new.start));
 374                let mut folds_cursor = self
 375                    .snapshot
 376                    .folds
 377                    .cursor::<FoldRange>(&inlay_snapshot.buffer);
 378                folds_cursor.seek(
 379                    &FoldRange(anchor..Anchor::max()),
 380                    Bias::Left,
 381                    &inlay_snapshot.buffer,
 382                );
 383
 384                let mut folds = iter::from_fn({
 385                    let inlay_snapshot = &inlay_snapshot;
 386                    move || {
 387                        let item = folds_cursor.item().map(|fold| {
 388                            let buffer_start = fold.range.start.to_offset(&inlay_snapshot.buffer);
 389                            let buffer_end = fold.range.end.to_offset(&inlay_snapshot.buffer);
 390                            (
 391                                fold.clone(),
 392                                inlay_snapshot.to_inlay_offset(buffer_start)
 393                                    ..inlay_snapshot.to_inlay_offset(buffer_end),
 394                            )
 395                        });
 396                        folds_cursor.next(&inlay_snapshot.buffer);
 397                        item
 398                    }
 399                })
 400                .peekable();
 401
 402                while folds
 403                    .peek()
 404                    .map_or(false, |(_, fold_range)| fold_range.start < edit.new.end)
 405                {
 406                    let (fold, mut fold_range) = folds.next().unwrap();
 407                    let sum = new_transforms.summary();
 408
 409                    assert!(fold_range.start.0 >= sum.input.len);
 410
 411                    while folds.peek().map_or(false, |(next_fold, next_fold_range)| {
 412                        next_fold_range.start < fold_range.end
 413                            || (next_fold_range.start == fold_range.end
 414                                && fold.placeholder.merge_adjacent
 415                                && next_fold.placeholder.merge_adjacent)
 416                    }) {
 417                        let (_, next_fold_range) = folds.next().unwrap();
 418                        if next_fold_range.end > fold_range.end {
 419                            fold_range.end = next_fold_range.end;
 420                        }
 421                    }
 422
 423                    if fold_range.start.0 > sum.input.len {
 424                        let text_summary = inlay_snapshot
 425                            .text_summary_for_range(InlayOffset(sum.input.len)..fold_range.start);
 426                        push_isomorphic(&mut new_transforms, text_summary);
 427                    }
 428
 429                    if fold_range.end > fold_range.start {
 430                        const ELLIPSIS: &str = "";
 431
 432                        let fold_id = fold.id;
 433                        new_transforms.push(
 434                            Transform {
 435                                summary: TransformSummary {
 436                                    output: TextSummary::from(ELLIPSIS),
 437                                    input: inlay_snapshot
 438                                        .text_summary_for_range(fold_range.start..fold_range.end),
 439                                },
 440                                placeholder: Some(TransformPlaceholder {
 441                                    text: ELLIPSIS,
 442                                    renderer: ChunkRenderer {
 443                                        render: Arc::new(move |cx| {
 444                                            (fold.placeholder.render)(
 445                                                fold_id,
 446                                                fold.range.0.clone(),
 447                                                cx,
 448                                            )
 449                                        }),
 450                                        constrain_width: fold.placeholder.constrain_width,
 451                                    },
 452                                }),
 453                            },
 454                            &(),
 455                        );
 456                    }
 457                }
 458
 459                let sum = new_transforms.summary();
 460                if sum.input.len < edit.new.end.0 {
 461                    let text_summary = inlay_snapshot
 462                        .text_summary_for_range(InlayOffset(sum.input.len)..edit.new.end);
 463                    push_isomorphic(&mut new_transforms, text_summary);
 464                }
 465            }
 466
 467            new_transforms.append(cursor.suffix(&()), &());
 468            if new_transforms.is_empty() {
 469                let text_summary = inlay_snapshot.text_summary();
 470                push_isomorphic(&mut new_transforms, text_summary);
 471            }
 472
 473            drop(cursor);
 474
 475            let mut fold_edits = Vec::with_capacity(inlay_edits.len());
 476            {
 477                let mut old_transforms = self
 478                    .snapshot
 479                    .transforms
 480                    .cursor::<(InlayOffset, FoldOffset)>(&());
 481                let mut new_transforms = new_transforms.cursor::<(InlayOffset, FoldOffset)>(&());
 482
 483                for mut edit in inlay_edits {
 484                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 485                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 486                        edit.old.start = old_transforms.start().0;
 487                    }
 488                    let old_start =
 489                        old_transforms.start().1 .0 + (edit.old.start - old_transforms.start().0).0;
 490
 491                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 492                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 493                        old_transforms.next(&());
 494                        edit.old.end = old_transforms.start().0;
 495                    }
 496                    let old_end =
 497                        old_transforms.start().1 .0 + (edit.old.end - old_transforms.start().0).0;
 498
 499                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 500                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 501                        edit.new.start = new_transforms.start().0;
 502                    }
 503                    let new_start =
 504                        new_transforms.start().1 .0 + (edit.new.start - new_transforms.start().0).0;
 505
 506                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 507                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 508                        new_transforms.next(&());
 509                        edit.new.end = new_transforms.start().0;
 510                    }
 511                    let new_end =
 512                        new_transforms.start().1 .0 + (edit.new.end - new_transforms.start().0).0;
 513
 514                    fold_edits.push(FoldEdit {
 515                        old: FoldOffset(old_start)..FoldOffset(old_end),
 516                        new: FoldOffset(new_start)..FoldOffset(new_end),
 517                    });
 518                }
 519
 520                fold_edits = consolidate_fold_edits(fold_edits);
 521            }
 522
 523            self.snapshot.transforms = new_transforms;
 524            self.snapshot.inlay_snapshot = inlay_snapshot;
 525            self.snapshot.version += 1;
 526            fold_edits
 527        }
 528    }
 529}
 530
 531#[derive(Clone)]
 532pub struct FoldSnapshot {
 533    transforms: SumTree<Transform>,
 534    folds: SumTree<Fold>,
 535    pub inlay_snapshot: InlaySnapshot,
 536    pub version: usize,
 537}
 538
 539impl FoldSnapshot {
 540    #[cfg(test)]
 541    pub fn text(&self) -> String {
 542        self.chunks(FoldOffset(0)..self.len(), false, Highlights::default())
 543            .map(|c| c.text)
 544            .collect()
 545    }
 546
 547    #[cfg(test)]
 548    pub fn fold_count(&self) -> usize {
 549        self.folds.items(&self.inlay_snapshot.buffer).len()
 550    }
 551
 552    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 553        let mut summary = TextSummary::default();
 554
 555        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 556        cursor.seek(&range.start, Bias::Right, &());
 557        if let Some(transform) = cursor.item() {
 558            let start_in_transform = range.start.0 - cursor.start().0 .0;
 559            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0 .0;
 560            if let Some(placeholder) = transform.placeholder.as_ref() {
 561                summary = TextSummary::from(
 562                    &placeholder.text
 563                        [start_in_transform.column as usize..end_in_transform.column as usize],
 564                );
 565            } else {
 566                let inlay_start = self
 567                    .inlay_snapshot
 568                    .to_offset(InlayPoint(cursor.start().1 .0 + start_in_transform));
 569                let inlay_end = self
 570                    .inlay_snapshot
 571                    .to_offset(InlayPoint(cursor.start().1 .0 + end_in_transform));
 572                summary = self
 573                    .inlay_snapshot
 574                    .text_summary_for_range(inlay_start..inlay_end);
 575            }
 576        }
 577
 578        if range.end > cursor.end(&()).0 {
 579            cursor.next(&());
 580            summary += &cursor
 581                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 582                .output;
 583            if let Some(transform) = cursor.item() {
 584                let end_in_transform = range.end.0 - cursor.start().0 .0;
 585                if let Some(placeholder) = transform.placeholder.as_ref() {
 586                    summary +=
 587                        TextSummary::from(&placeholder.text[..end_in_transform.column as usize]);
 588                } else {
 589                    let inlay_start = self.inlay_snapshot.to_offset(cursor.start().1);
 590                    let inlay_end = self
 591                        .inlay_snapshot
 592                        .to_offset(InlayPoint(cursor.start().1 .0 + end_in_transform));
 593                    summary += self
 594                        .inlay_snapshot
 595                        .text_summary_for_range(inlay_start..inlay_end);
 596                }
 597            }
 598        }
 599
 600        summary
 601    }
 602
 603    pub fn to_fold_point(&self, point: InlayPoint, bias: Bias) -> FoldPoint {
 604        let mut cursor = self.transforms.cursor::<(InlayPoint, FoldPoint)>(&());
 605        cursor.seek(&point, Bias::Right, &());
 606        if cursor.item().map_or(false, |t| t.is_fold()) {
 607            if bias == Bias::Left || point == cursor.start().0 {
 608                cursor.start().1
 609            } else {
 610                cursor.end(&()).1
 611            }
 612        } else {
 613            let overshoot = point.0 - cursor.start().0 .0;
 614            FoldPoint(cmp::min(
 615                cursor.start().1 .0 + overshoot,
 616                cursor.end(&()).1 .0,
 617            ))
 618        }
 619    }
 620
 621    pub fn len(&self) -> FoldOffset {
 622        FoldOffset(self.transforms.summary().output.len)
 623    }
 624
 625    pub fn line_len(&self, row: u32) -> u32 {
 626        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 627        let line_end = if row >= self.max_point().row() {
 628            self.len().0
 629        } else {
 630            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 631        };
 632        (line_end - line_start) as u32
 633    }
 634
 635    pub fn buffer_rows(&self, start_row: u32) -> FoldBufferRows {
 636        if start_row > self.transforms.summary().output.lines.row {
 637            panic!("invalid display row {}", start_row);
 638        }
 639
 640        let fold_point = FoldPoint::new(start_row, 0);
 641        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 642        cursor.seek(&fold_point, Bias::Left, &());
 643
 644        let overshoot = fold_point.0 - cursor.start().0 .0;
 645        let inlay_point = InlayPoint(cursor.start().1 .0 + overshoot);
 646        let input_buffer_rows = self.inlay_snapshot.buffer_rows(inlay_point.row());
 647
 648        FoldBufferRows {
 649            fold_point,
 650            input_buffer_rows,
 651            cursor,
 652        }
 653    }
 654
 655    pub fn max_point(&self) -> FoldPoint {
 656        FoldPoint(self.transforms.summary().output.lines)
 657    }
 658
 659    #[cfg(test)]
 660    pub fn longest_row(&self) -> u32 {
 661        self.transforms.summary().output.longest_row
 662    }
 663
 664    pub fn folds_in_range<T>(&self, range: Range<T>) -> impl Iterator<Item = &Fold>
 665    where
 666        T: ToOffset,
 667    {
 668        let mut folds = intersecting_folds(&self.inlay_snapshot, &self.folds, range, false);
 669        iter::from_fn(move || {
 670            let item = folds.item();
 671            folds.next(&self.inlay_snapshot.buffer);
 672            item
 673        })
 674    }
 675
 676    pub fn intersects_fold<T>(&self, offset: T) -> bool
 677    where
 678        T: ToOffset,
 679    {
 680        let buffer_offset = offset.to_offset(&self.inlay_snapshot.buffer);
 681        let inlay_offset = self.inlay_snapshot.to_inlay_offset(buffer_offset);
 682        let mut cursor = self.transforms.cursor::<InlayOffset>(&());
 683        cursor.seek(&inlay_offset, Bias::Right, &());
 684        cursor.item().map_or(false, |t| t.placeholder.is_some())
 685    }
 686
 687    pub fn is_line_folded(&self, buffer_row: MultiBufferRow) -> bool {
 688        let mut inlay_point = self
 689            .inlay_snapshot
 690            .to_inlay_point(Point::new(buffer_row.0, 0));
 691        let mut cursor = self.transforms.cursor::<InlayPoint>(&());
 692        cursor.seek(&inlay_point, Bias::Right, &());
 693        loop {
 694            match cursor.item() {
 695                Some(transform) => {
 696                    let buffer_point = self.inlay_snapshot.to_buffer_point(inlay_point);
 697                    if buffer_point.row != buffer_row.0 {
 698                        return false;
 699                    } else if transform.placeholder.is_some() {
 700                        return true;
 701                    }
 702                }
 703                None => return false,
 704            }
 705
 706            if cursor.end(&()).row() == inlay_point.row() {
 707                cursor.next(&());
 708            } else {
 709                inlay_point.0 += Point::new(1, 0);
 710                cursor.seek(&inlay_point, Bias::Right, &());
 711            }
 712        }
 713    }
 714
 715    pub(crate) fn chunks<'a>(
 716        &'a self,
 717        range: Range<FoldOffset>,
 718        language_aware: bool,
 719        highlights: Highlights<'a>,
 720    ) -> FoldChunks<'a> {
 721        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, InlayOffset)>(&());
 722        transform_cursor.seek(&range.start, Bias::Right, &());
 723
 724        let inlay_start = {
 725            let overshoot = range.start.0 - transform_cursor.start().0 .0;
 726            transform_cursor.start().1 + InlayOffset(overshoot)
 727        };
 728
 729        let transform_end = transform_cursor.end(&());
 730
 731        let inlay_end = if transform_cursor
 732            .item()
 733            .map_or(true, |transform| transform.is_fold())
 734        {
 735            inlay_start
 736        } else if range.end < transform_end.0 {
 737            let overshoot = range.end.0 - transform_cursor.start().0 .0;
 738            transform_cursor.start().1 + InlayOffset(overshoot)
 739        } else {
 740            transform_end.1
 741        };
 742
 743        FoldChunks {
 744            transform_cursor,
 745            inlay_chunks: self.inlay_snapshot.chunks(
 746                inlay_start..inlay_end,
 747                language_aware,
 748                highlights,
 749            ),
 750            inlay_chunk: None,
 751            inlay_offset: inlay_start,
 752            output_offset: range.start,
 753            max_output_offset: range.end,
 754        }
 755    }
 756
 757    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 758        self.chunks(
 759            start.to_offset(self)..self.len(),
 760            false,
 761            Highlights::default(),
 762        )
 763        .flat_map(|chunk| chunk.text.chars())
 764    }
 765
 766    #[cfg(test)]
 767    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 768        if offset > self.len() {
 769            self.len()
 770        } else {
 771            self.clip_point(offset.to_point(self), bias).to_offset(self)
 772        }
 773    }
 774
 775    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 776        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 777        cursor.seek(&point, Bias::Right, &());
 778        if let Some(transform) = cursor.item() {
 779            let transform_start = cursor.start().0 .0;
 780            if transform.placeholder.is_some() {
 781                if point.0 == transform_start || matches!(bias, Bias::Left) {
 782                    FoldPoint(transform_start)
 783                } else {
 784                    FoldPoint(cursor.end(&()).0 .0)
 785                }
 786            } else {
 787                let overshoot = InlayPoint(point.0 - transform_start);
 788                let inlay_point = cursor.start().1 + overshoot;
 789                let clipped_inlay_point = self.inlay_snapshot.clip_point(inlay_point, bias);
 790                FoldPoint(cursor.start().0 .0 + (clipped_inlay_point - cursor.start().1).0)
 791            }
 792        } else {
 793            FoldPoint(self.transforms.summary().output.lines)
 794        }
 795    }
 796}
 797
 798fn push_isomorphic(transforms: &mut SumTree<Transform>, summary: TextSummary) {
 799    let mut did_merge = false;
 800    transforms.update_last(
 801        |last| {
 802            if !last.is_fold() {
 803                last.summary.input += summary.clone();
 804                last.summary.output += summary.clone();
 805                did_merge = true;
 806            }
 807        },
 808        &(),
 809    );
 810    if !did_merge {
 811        transforms.push(
 812            Transform {
 813                summary: TransformSummary {
 814                    input: summary.clone(),
 815                    output: summary,
 816                },
 817                placeholder: None,
 818            },
 819            &(),
 820        )
 821    }
 822}
 823
 824fn intersecting_folds<'a, T>(
 825    inlay_snapshot: &'a InlaySnapshot,
 826    folds: &'a SumTree<Fold>,
 827    range: Range<T>,
 828    inclusive: bool,
 829) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize>
 830where
 831    T: ToOffset,
 832{
 833    let buffer = &inlay_snapshot.buffer;
 834    let start = buffer.anchor_before(range.start.to_offset(buffer));
 835    let end = buffer.anchor_after(range.end.to_offset(buffer));
 836    let mut cursor = folds.filter::<_, usize>(buffer, move |summary| {
 837        let start_cmp = start.cmp(&summary.max_end, buffer);
 838        let end_cmp = end.cmp(&summary.min_start, buffer);
 839
 840        if inclusive {
 841            start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 842        } else {
 843            start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 844        }
 845    });
 846    cursor.next(buffer);
 847    cursor
 848}
 849
 850fn consolidate_inlay_edits(mut edits: Vec<InlayEdit>) -> Vec<InlayEdit> {
 851    edits.sort_unstable_by(|a, b| {
 852        a.old
 853            .start
 854            .cmp(&b.old.start)
 855            .then_with(|| b.old.end.cmp(&a.old.end))
 856    });
 857
 858    let _old_alloc_ptr = edits.as_ptr();
 859    let mut inlay_edits = edits.into_iter();
 860
 861    if let Some(mut first_edit) = inlay_edits.next() {
 862        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
 863        #[allow(clippy::filter_map_identity)]
 864        let mut v: Vec<_> = inlay_edits
 865            .scan(&mut first_edit, |prev_edit, edit| {
 866                if prev_edit.old.end >= edit.old.start {
 867                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 868                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 869                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 870                    Some(None) // Skip this edit, it's merged
 871                } else {
 872                    let prev = std::mem::replace(*prev_edit, edit);
 873                    Some(Some(prev)) // Yield the previous edit
 874                }
 875            })
 876            .filter_map(|x| x)
 877            .collect();
 878        v.push(first_edit.clone());
 879        debug_assert_eq!(_old_alloc_ptr, v.as_ptr(), "Inlay edits were reallocated");
 880        v
 881    } else {
 882        vec![]
 883    }
 884}
 885
 886fn consolidate_fold_edits(mut edits: Vec<FoldEdit>) -> Vec<FoldEdit> {
 887    edits.sort_unstable_by(|a, b| {
 888        a.old
 889            .start
 890            .cmp(&b.old.start)
 891            .then_with(|| b.old.end.cmp(&a.old.end))
 892    });
 893    let _old_alloc_ptr = edits.as_ptr();
 894    let mut fold_edits = edits.into_iter();
 895
 896    if let Some(mut first_edit) = fold_edits.next() {
 897        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
 898        #[allow(clippy::filter_map_identity)]
 899        let mut v: Vec<_> = fold_edits
 900            .scan(&mut first_edit, |prev_edit, edit| {
 901                if prev_edit.old.end >= edit.old.start {
 902                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 903                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 904                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 905                    Some(None) // Skip this edit, it's merged
 906                } else {
 907                    let prev = std::mem::replace(*prev_edit, edit);
 908                    Some(Some(prev)) // Yield the previous edit
 909                }
 910            })
 911            .filter_map(|x| x)
 912            .collect();
 913        v.push(first_edit.clone());
 914        v
 915    } else {
 916        vec![]
 917    }
 918}
 919
 920#[derive(Clone, Debug, Default)]
 921struct Transform {
 922    summary: TransformSummary,
 923    placeholder: Option<TransformPlaceholder>,
 924}
 925
 926#[derive(Clone, Debug)]
 927struct TransformPlaceholder {
 928    text: &'static str,
 929    renderer: ChunkRenderer,
 930}
 931
 932impl Transform {
 933    fn is_fold(&self) -> bool {
 934        self.placeholder.is_some()
 935    }
 936}
 937
 938#[derive(Clone, Debug, Default, Eq, PartialEq)]
 939struct TransformSummary {
 940    output: TextSummary,
 941    input: TextSummary,
 942}
 943
 944impl sum_tree::Item for Transform {
 945    type Summary = TransformSummary;
 946
 947    fn summary(&self, _cx: &()) -> Self::Summary {
 948        self.summary.clone()
 949    }
 950}
 951
 952impl sum_tree::Summary for TransformSummary {
 953    type Context = ();
 954
 955    fn zero(_cx: &()) -> Self {
 956        Default::default()
 957    }
 958
 959    fn add_summary(&mut self, other: &Self, _: &()) {
 960        self.input += &other.input;
 961        self.output += &other.output;
 962    }
 963}
 964
 965#[derive(Copy, Clone, Eq, PartialEq, Debug, Default)]
 966pub struct FoldId(usize);
 967
 968impl From<FoldId> for ElementId {
 969    fn from(val: FoldId) -> Self {
 970        ElementId::Integer(val.0)
 971    }
 972}
 973
 974#[derive(Clone, Debug, Eq, PartialEq)]
 975pub struct Fold {
 976    pub id: FoldId,
 977    pub range: FoldRange,
 978    pub placeholder: FoldPlaceholder,
 979}
 980
 981#[derive(Clone, Debug, Eq, PartialEq)]
 982pub struct FoldRange(Range<Anchor>);
 983
 984impl Deref for FoldRange {
 985    type Target = Range<Anchor>;
 986
 987    fn deref(&self) -> &Self::Target {
 988        &self.0
 989    }
 990}
 991
 992impl DerefMut for FoldRange {
 993    fn deref_mut(&mut self) -> &mut Self::Target {
 994        &mut self.0
 995    }
 996}
 997
 998impl Default for FoldRange {
 999    fn default() -> Self {
1000        Self(Anchor::min()..Anchor::max())
1001    }
1002}
1003
1004impl sum_tree::Item for Fold {
1005    type Summary = FoldSummary;
1006
1007    fn summary(&self, _cx: &MultiBufferSnapshot) -> Self::Summary {
1008        FoldSummary {
1009            start: self.range.start,
1010            end: self.range.end,
1011            min_start: self.range.start,
1012            max_end: self.range.end,
1013            count: 1,
1014        }
1015    }
1016}
1017
1018#[derive(Clone, Debug)]
1019pub struct FoldSummary {
1020    start: Anchor,
1021    end: Anchor,
1022    min_start: Anchor,
1023    max_end: Anchor,
1024    count: usize,
1025}
1026
1027impl Default for FoldSummary {
1028    fn default() -> Self {
1029        Self {
1030            start: Anchor::min(),
1031            end: Anchor::max(),
1032            min_start: Anchor::max(),
1033            max_end: Anchor::min(),
1034            count: 0,
1035        }
1036    }
1037}
1038
1039impl sum_tree::Summary for FoldSummary {
1040    type Context = MultiBufferSnapshot;
1041
1042    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1043        Default::default()
1044    }
1045
1046    fn add_summary(&mut self, other: &Self, buffer: &Self::Context) {
1047        if other.min_start.cmp(&self.min_start, buffer) == Ordering::Less {
1048            self.min_start = other.min_start;
1049        }
1050        if other.max_end.cmp(&self.max_end, buffer) == Ordering::Greater {
1051            self.max_end = other.max_end;
1052        }
1053
1054        #[cfg(debug_assertions)]
1055        {
1056            let start_comparison = self.start.cmp(&other.start, buffer);
1057            assert!(start_comparison <= Ordering::Equal);
1058            if start_comparison == Ordering::Equal {
1059                assert!(self.end.cmp(&other.end, buffer) >= Ordering::Equal);
1060            }
1061        }
1062
1063        self.start = other.start;
1064        self.end = other.end;
1065        self.count += other.count;
1066    }
1067}
1068
1069impl<'a> sum_tree::Dimension<'a, FoldSummary> for FoldRange {
1070    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1071        Default::default()
1072    }
1073
1074    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1075        self.0.start = summary.start;
1076        self.0.end = summary.end;
1077    }
1078}
1079
1080impl<'a> sum_tree::SeekTarget<'a, FoldSummary, FoldRange> for FoldRange {
1081    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
1082        AnchorRangeExt::cmp(&self.0, &other.0, buffer)
1083    }
1084}
1085
1086impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
1087    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1088        Default::default()
1089    }
1090
1091    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1092        *self += summary.count;
1093    }
1094}
1095
1096#[derive(Clone)]
1097pub struct FoldBufferRows<'a> {
1098    cursor: Cursor<'a, Transform, (FoldPoint, InlayPoint)>,
1099    input_buffer_rows: InlayBufferRows<'a>,
1100    fold_point: FoldPoint,
1101}
1102
1103impl<'a> FoldBufferRows<'a> {
1104    pub(crate) fn seek(&mut self, row: u32) {
1105        let fold_point = FoldPoint::new(row, 0);
1106        self.cursor.seek(&fold_point, Bias::Left, &());
1107        let overshoot = fold_point.0 - self.cursor.start().0 .0;
1108        let inlay_point = InlayPoint(self.cursor.start().1 .0 + overshoot);
1109        self.input_buffer_rows.seek(inlay_point.row());
1110        self.fold_point = fold_point;
1111    }
1112}
1113
1114impl<'a> Iterator for FoldBufferRows<'a> {
1115    type Item = Option<u32>;
1116
1117    fn next(&mut self) -> Option<Self::Item> {
1118        let mut traversed_fold = false;
1119        while self.fold_point > self.cursor.end(&()).0 {
1120            self.cursor.next(&());
1121            traversed_fold = true;
1122            if self.cursor.item().is_none() {
1123                break;
1124            }
1125        }
1126
1127        if self.cursor.item().is_some() {
1128            if traversed_fold {
1129                self.input_buffer_rows.seek(self.cursor.start().1.row());
1130                self.input_buffer_rows.next();
1131            }
1132            *self.fold_point.row_mut() += 1;
1133            self.input_buffer_rows.next()
1134        } else {
1135            None
1136        }
1137    }
1138}
1139
1140pub struct FoldChunks<'a> {
1141    transform_cursor: Cursor<'a, Transform, (FoldOffset, InlayOffset)>,
1142    inlay_chunks: InlayChunks<'a>,
1143    inlay_chunk: Option<(InlayOffset, Chunk<'a>)>,
1144    inlay_offset: InlayOffset,
1145    output_offset: FoldOffset,
1146    max_output_offset: FoldOffset,
1147}
1148
1149impl<'a> FoldChunks<'a> {
1150    pub(crate) fn seek(&mut self, range: Range<FoldOffset>) {
1151        self.transform_cursor.seek(&range.start, Bias::Right, &());
1152
1153        let inlay_start = {
1154            let overshoot = range.start.0 - self.transform_cursor.start().0 .0;
1155            self.transform_cursor.start().1 + InlayOffset(overshoot)
1156        };
1157
1158        let transform_end = self.transform_cursor.end(&());
1159
1160        let inlay_end = if self
1161            .transform_cursor
1162            .item()
1163            .map_or(true, |transform| transform.is_fold())
1164        {
1165            inlay_start
1166        } else if range.end < transform_end.0 {
1167            let overshoot = range.end.0 - self.transform_cursor.start().0 .0;
1168            self.transform_cursor.start().1 + InlayOffset(overshoot)
1169        } else {
1170            transform_end.1
1171        };
1172
1173        self.inlay_chunks.seek(inlay_start..inlay_end);
1174        self.inlay_chunk = None;
1175        self.inlay_offset = inlay_start;
1176        self.output_offset = range.start;
1177        self.max_output_offset = range.end;
1178    }
1179}
1180
1181impl<'a> Iterator for FoldChunks<'a> {
1182    type Item = Chunk<'a>;
1183
1184    fn next(&mut self) -> Option<Self::Item> {
1185        if self.output_offset >= self.max_output_offset {
1186            return None;
1187        }
1188
1189        let transform = self.transform_cursor.item()?;
1190
1191        // If we're in a fold, then return the fold's display text and
1192        // advance the transform and buffer cursors to the end of the fold.
1193        if let Some(placeholder) = transform.placeholder.as_ref() {
1194            self.inlay_chunk.take();
1195            self.inlay_offset += InlayOffset(transform.summary.input.len);
1196
1197            while self.inlay_offset >= self.transform_cursor.end(&()).1
1198                && self.transform_cursor.item().is_some()
1199            {
1200                self.transform_cursor.next(&());
1201            }
1202
1203            self.output_offset.0 += placeholder.text.len();
1204            return Some(Chunk {
1205                text: placeholder.text,
1206                renderer: Some(placeholder.renderer.clone()),
1207                ..Default::default()
1208            });
1209        }
1210
1211        // When we reach a non-fold region, seek the underlying text
1212        // chunk iterator to the next unfolded range.
1213        if self.inlay_offset == self.transform_cursor.start().1
1214            && self.inlay_chunks.offset() != self.inlay_offset
1215        {
1216            let transform_start = self.transform_cursor.start();
1217            let transform_end = self.transform_cursor.end(&());
1218            let inlay_end = if self.max_output_offset < transform_end.0 {
1219                let overshoot = self.max_output_offset.0 - transform_start.0 .0;
1220                transform_start.1 + InlayOffset(overshoot)
1221            } else {
1222                transform_end.1
1223            };
1224
1225            self.inlay_chunks.seek(self.inlay_offset..inlay_end);
1226        }
1227
1228        // Retrieve a chunk from the current location in the buffer.
1229        if self.inlay_chunk.is_none() {
1230            let chunk_offset = self.inlay_chunks.offset();
1231            self.inlay_chunk = self.inlay_chunks.next().map(|chunk| (chunk_offset, chunk));
1232        }
1233
1234        // Otherwise, take a chunk from the buffer's text.
1235        if let Some((buffer_chunk_start, mut chunk)) = self.inlay_chunk.clone() {
1236            let buffer_chunk_end = buffer_chunk_start + InlayOffset(chunk.text.len());
1237            let transform_end = self.transform_cursor.end(&()).1;
1238            let chunk_end = buffer_chunk_end.min(transform_end);
1239
1240            chunk.text = &chunk.text
1241                [(self.inlay_offset - buffer_chunk_start).0..(chunk_end - buffer_chunk_start).0];
1242
1243            if chunk_end == transform_end {
1244                self.transform_cursor.next(&());
1245            } else if chunk_end == buffer_chunk_end {
1246                self.inlay_chunk.take();
1247            }
1248
1249            self.inlay_offset = chunk_end;
1250            self.output_offset.0 += chunk.text.len();
1251            return Some(chunk);
1252        }
1253
1254        None
1255    }
1256}
1257
1258#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1259pub struct FoldOffset(pub usize);
1260
1261impl FoldOffset {
1262    pub fn to_point(self, snapshot: &FoldSnapshot) -> FoldPoint {
1263        let mut cursor = snapshot
1264            .transforms
1265            .cursor::<(FoldOffset, TransformSummary)>(&());
1266        cursor.seek(&self, Bias::Right, &());
1267        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1268            Point::new(0, (self.0 - cursor.start().0 .0) as u32)
1269        } else {
1270            let inlay_offset = cursor.start().1.input.len + self.0 - cursor.start().0 .0;
1271            let inlay_point = snapshot.inlay_snapshot.to_point(InlayOffset(inlay_offset));
1272            inlay_point.0 - cursor.start().1.input.lines
1273        };
1274        FoldPoint(cursor.start().1.output.lines + overshoot)
1275    }
1276
1277    #[cfg(test)]
1278    pub fn to_inlay_offset(self, snapshot: &FoldSnapshot) -> InlayOffset {
1279        let mut cursor = snapshot.transforms.cursor::<(FoldOffset, InlayOffset)>(&());
1280        cursor.seek(&self, Bias::Right, &());
1281        let overshoot = self.0 - cursor.start().0 .0;
1282        InlayOffset(cursor.start().1 .0 + overshoot)
1283    }
1284}
1285
1286impl Add for FoldOffset {
1287    type Output = Self;
1288
1289    fn add(self, rhs: Self) -> Self::Output {
1290        Self(self.0 + rhs.0)
1291    }
1292}
1293
1294impl AddAssign for FoldOffset {
1295    fn add_assign(&mut self, rhs: Self) {
1296        self.0 += rhs.0;
1297    }
1298}
1299
1300impl Sub for FoldOffset {
1301    type Output = Self;
1302
1303    fn sub(self, rhs: Self) -> Self::Output {
1304        Self(self.0 - rhs.0)
1305    }
1306}
1307
1308impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1309    fn zero(_cx: &()) -> Self {
1310        Default::default()
1311    }
1312
1313    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1314        self.0 += &summary.output.len;
1315    }
1316}
1317
1318impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayPoint {
1319    fn zero(_cx: &()) -> Self {
1320        Default::default()
1321    }
1322
1323    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1324        self.0 += &summary.input.lines;
1325    }
1326}
1327
1328impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayOffset {
1329    fn zero(_cx: &()) -> Self {
1330        Default::default()
1331    }
1332
1333    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1334        self.0 += &summary.input.len;
1335    }
1336}
1337
1338pub type FoldEdit = Edit<FoldOffset>;
1339
1340#[cfg(test)]
1341mod tests {
1342    use super::*;
1343    use crate::{display_map::inlay_map::InlayMap, MultiBuffer, ToPoint};
1344    use collections::HashSet;
1345    use rand::prelude::*;
1346    use settings::SettingsStore;
1347    use std::{env, mem};
1348    use text::Patch;
1349    use util::test::sample_text;
1350    use util::RandomCharIter;
1351    use Bias::{Left, Right};
1352
1353    #[gpui::test]
1354    fn test_basic_folds(cx: &mut gpui::AppContext) {
1355        init_test(cx);
1356        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1357        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1358        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1359        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1360        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1361
1362        let (mut writer, _, _) = map.write(inlay_snapshot, vec![]);
1363        let (snapshot2, edits) = writer.fold(vec![
1364            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1365            (Point::new(2, 4)..Point::new(4, 1), FoldPlaceholder::test()),
1366        ]);
1367        assert_eq!(snapshot2.text(), "aa⋯cc⋯eeeee");
1368        assert_eq!(
1369            edits,
1370            &[
1371                FoldEdit {
1372                    old: FoldOffset(2)..FoldOffset(16),
1373                    new: FoldOffset(2)..FoldOffset(5),
1374                },
1375                FoldEdit {
1376                    old: FoldOffset(18)..FoldOffset(29),
1377                    new: FoldOffset(7)..FoldOffset(10)
1378                },
1379            ]
1380        );
1381
1382        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1383            buffer.edit(
1384                vec![
1385                    (Point::new(0, 0)..Point::new(0, 1), "123"),
1386                    (Point::new(2, 3)..Point::new(2, 3), "123"),
1387                ],
1388                None,
1389                cx,
1390            );
1391            buffer.snapshot(cx)
1392        });
1393
1394        let (inlay_snapshot, inlay_edits) =
1395            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1396        let (snapshot3, edits) = map.read(inlay_snapshot, inlay_edits);
1397        assert_eq!(snapshot3.text(), "123a⋯c123c⋯eeeee");
1398        assert_eq!(
1399            edits,
1400            &[
1401                FoldEdit {
1402                    old: FoldOffset(0)..FoldOffset(1),
1403                    new: FoldOffset(0)..FoldOffset(3),
1404                },
1405                FoldEdit {
1406                    old: FoldOffset(6)..FoldOffset(6),
1407                    new: FoldOffset(8)..FoldOffset(11),
1408                },
1409            ]
1410        );
1411
1412        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1413            buffer.edit([(Point::new(2, 6)..Point::new(4, 3), "456")], None, cx);
1414            buffer.snapshot(cx)
1415        });
1416        let (inlay_snapshot, inlay_edits) =
1417            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1418        let (snapshot4, _) = map.read(inlay_snapshot.clone(), inlay_edits);
1419        assert_eq!(snapshot4.text(), "123a⋯c123456eee");
1420
1421        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1422        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 4)), false);
1423        let (snapshot5, _) = map.read(inlay_snapshot.clone(), vec![]);
1424        assert_eq!(snapshot5.text(), "123a⋯c123456eee");
1425
1426        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1427        writer.unfold(Some(Point::new(0, 4)..Point::new(0, 4)), true);
1428        let (snapshot6, _) = map.read(inlay_snapshot, vec![]);
1429        assert_eq!(snapshot6.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1430    }
1431
1432    #[gpui::test]
1433    fn test_adjacent_folds(cx: &mut gpui::AppContext) {
1434        init_test(cx);
1435        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1436        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1437        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1438        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1439
1440        {
1441            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1442
1443            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1444            writer.fold(vec![(5..8, FoldPlaceholder::test())]);
1445            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1446            assert_eq!(snapshot.text(), "abcde⋯ijkl");
1447
1448            // Create an fold adjacent to the start of the first fold.
1449            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1450            writer.fold(vec![
1451                (0..1, FoldPlaceholder::test()),
1452                (2..5, FoldPlaceholder::test()),
1453            ]);
1454            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1455            assert_eq!(snapshot.text(), "⋯b⋯ijkl");
1456
1457            // Create an fold adjacent to the end of the first fold.
1458            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1459            writer.fold(vec![
1460                (11..11, FoldPlaceholder::test()),
1461                (8..10, FoldPlaceholder::test()),
1462            ]);
1463            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1464            assert_eq!(snapshot.text(), "⋯b⋯kl");
1465        }
1466
1467        {
1468            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1469
1470            // Create two adjacent folds.
1471            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1472            writer.fold(vec![
1473                (0..2, FoldPlaceholder::test()),
1474                (2..5, FoldPlaceholder::test()),
1475            ]);
1476            let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1477            assert_eq!(snapshot.text(), "⋯fghijkl");
1478
1479            // Edit within one of the folds.
1480            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1481                buffer.edit([(0..1, "12345")], None, cx);
1482                buffer.snapshot(cx)
1483            });
1484            let (inlay_snapshot, inlay_edits) =
1485                inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1486            let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1487            assert_eq!(snapshot.text(), "12345⋯fghijkl");
1488        }
1489    }
1490
1491    #[gpui::test]
1492    fn test_overlapping_folds(cx: &mut gpui::AppContext) {
1493        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1494        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1495        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1496        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1497        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1498        writer.fold(vec![
1499            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1500            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1501            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1502            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1503        ]);
1504        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1505        assert_eq!(snapshot.text(), "aa⋯eeeee");
1506    }
1507
1508    #[gpui::test]
1509    fn test_merging_folds_via_edit(cx: &mut gpui::AppContext) {
1510        init_test(cx);
1511        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1512        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1513        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1514        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1515        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1516
1517        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1518        writer.fold(vec![
1519            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1520            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1521        ]);
1522        let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1523        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee");
1524
1525        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1526            buffer.edit([(Point::new(2, 2)..Point::new(3, 1), "")], None, cx);
1527            buffer.snapshot(cx)
1528        });
1529        let (inlay_snapshot, inlay_edits) =
1530            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1531        let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1532        assert_eq!(snapshot.text(), "aa⋯eeeee");
1533    }
1534
1535    #[gpui::test]
1536    fn test_folds_in_range(cx: &mut gpui::AppContext) {
1537        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1538        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1539        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1540        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1541
1542        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1543        writer.fold(vec![
1544            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1545            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1546            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1547            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1548        ]);
1549        let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1550        let fold_ranges = snapshot
1551            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1552            .map(|fold| {
1553                fold.range.start.to_point(&buffer_snapshot)
1554                    ..fold.range.end.to_point(&buffer_snapshot)
1555            })
1556            .collect::<Vec<_>>();
1557        assert_eq!(
1558            fold_ranges,
1559            vec![
1560                Point::new(0, 2)..Point::new(2, 2),
1561                Point::new(1, 2)..Point::new(3, 2)
1562            ]
1563        );
1564    }
1565
1566    #[gpui::test(iterations = 100)]
1567    fn test_random_folds(cx: &mut gpui::AppContext, mut rng: StdRng) {
1568        init_test(cx);
1569        let operations = env::var("OPERATIONS")
1570            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1571            .unwrap_or(10);
1572
1573        let len = rng.gen_range(0..10);
1574        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1575        let buffer = if rng.gen() {
1576            MultiBuffer::build_simple(&text, cx)
1577        } else {
1578            MultiBuffer::build_random(&mut rng, cx)
1579        };
1580        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1581        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1582        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1583
1584        let (mut initial_snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1585        let mut snapshot_edits = Vec::new();
1586
1587        let mut next_inlay_id = 0;
1588        for _ in 0..operations {
1589            log::info!("text: {:?}", buffer_snapshot.text());
1590            let mut buffer_edits = Vec::new();
1591            let mut inlay_edits = Vec::new();
1592            match rng.gen_range(0..=100) {
1593                0..=39 => {
1594                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1595                }
1596                40..=59 => {
1597                    let (_, edits) = inlay_map.randomly_mutate(&mut next_inlay_id, &mut rng);
1598                    inlay_edits = edits;
1599                }
1600                _ => buffer.update(cx, |buffer, cx| {
1601                    let subscription = buffer.subscribe();
1602                    let edit_count = rng.gen_range(1..=5);
1603                    buffer.randomly_mutate(&mut rng, edit_count, cx);
1604                    buffer_snapshot = buffer.snapshot(cx);
1605                    let edits = subscription.consume().into_inner();
1606                    log::info!("editing {:?}", edits);
1607                    buffer_edits.extend(edits);
1608                }),
1609            };
1610
1611            let (inlay_snapshot, new_inlay_edits) =
1612                inlay_map.sync(buffer_snapshot.clone(), buffer_edits);
1613            log::info!("inlay text {:?}", inlay_snapshot.text());
1614
1615            let inlay_edits = Patch::new(inlay_edits)
1616                .compose(new_inlay_edits)
1617                .into_inner();
1618            let (snapshot, edits) = map.read(inlay_snapshot.clone(), inlay_edits);
1619            snapshot_edits.push((snapshot.clone(), edits));
1620
1621            let mut expected_text: String = inlay_snapshot.text().to_string();
1622            for fold_range in map.merged_folds().into_iter().rev() {
1623                let fold_inlay_start = inlay_snapshot.to_inlay_offset(fold_range.start);
1624                let fold_inlay_end = inlay_snapshot.to_inlay_offset(fold_range.end);
1625                expected_text.replace_range(fold_inlay_start.0..fold_inlay_end.0, "");
1626            }
1627
1628            assert_eq!(snapshot.text(), expected_text);
1629            log::info!(
1630                "fold text {:?} ({} lines)",
1631                expected_text,
1632                expected_text.matches('\n').count() + 1
1633            );
1634
1635            let mut prev_row = 0;
1636            let mut expected_buffer_rows = Vec::new();
1637            for fold_range in map.merged_folds() {
1638                let fold_start = inlay_snapshot
1639                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.start))
1640                    .row();
1641                let fold_end = inlay_snapshot
1642                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.end))
1643                    .row();
1644                expected_buffer_rows.extend(
1645                    inlay_snapshot
1646                        .buffer_rows(prev_row)
1647                        .take((1 + fold_start - prev_row) as usize),
1648                );
1649                prev_row = 1 + fold_end;
1650            }
1651            expected_buffer_rows.extend(inlay_snapshot.buffer_rows(prev_row));
1652
1653            assert_eq!(
1654                expected_buffer_rows.len(),
1655                expected_text.matches('\n').count() + 1,
1656                "wrong expected buffer rows {:?}. text: {:?}",
1657                expected_buffer_rows,
1658                expected_text
1659            );
1660
1661            for (output_row, line) in expected_text.lines().enumerate() {
1662                let line_len = snapshot.line_len(output_row as u32);
1663                assert_eq!(line_len, line.len() as u32);
1664            }
1665
1666            let longest_row = snapshot.longest_row();
1667            let longest_char_column = expected_text
1668                .split('\n')
1669                .nth(longest_row as usize)
1670                .unwrap()
1671                .chars()
1672                .count();
1673            let mut fold_point = FoldPoint::new(0, 0);
1674            let mut fold_offset = FoldOffset(0);
1675            let mut char_column = 0;
1676            for c in expected_text.chars() {
1677                let inlay_point = fold_point.to_inlay_point(&snapshot);
1678                let inlay_offset = fold_offset.to_inlay_offset(&snapshot);
1679                assert_eq!(
1680                    snapshot.to_fold_point(inlay_point, Right),
1681                    fold_point,
1682                    "{:?} -> fold point",
1683                    inlay_point,
1684                );
1685                assert_eq!(
1686                    inlay_snapshot.to_offset(inlay_point),
1687                    inlay_offset,
1688                    "inlay_snapshot.to_offset({:?})",
1689                    inlay_point,
1690                );
1691                assert_eq!(
1692                    fold_point.to_offset(&snapshot),
1693                    fold_offset,
1694                    "fold_point.to_offset({:?})",
1695                    fold_point,
1696                );
1697
1698                if c == '\n' {
1699                    *fold_point.row_mut() += 1;
1700                    *fold_point.column_mut() = 0;
1701                    char_column = 0;
1702                } else {
1703                    *fold_point.column_mut() += c.len_utf8() as u32;
1704                    char_column += 1;
1705                }
1706                fold_offset.0 += c.len_utf8();
1707                if char_column > longest_char_column {
1708                    panic!(
1709                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1710                        longest_row,
1711                        longest_char_column,
1712                        fold_point.row(),
1713                        char_column
1714                    );
1715                }
1716            }
1717
1718            for _ in 0..5 {
1719                let mut start = snapshot
1720                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1721                let mut end = snapshot
1722                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1723                if start > end {
1724                    mem::swap(&mut start, &mut end);
1725                }
1726
1727                let text = &expected_text[start.0..end.0];
1728                assert_eq!(
1729                    snapshot
1730                        .chunks(start..end, false, Highlights::default())
1731                        .map(|c| c.text)
1732                        .collect::<String>(),
1733                    text,
1734                );
1735            }
1736
1737            let mut fold_row = 0;
1738            while fold_row < expected_buffer_rows.len() as u32 {
1739                assert_eq!(
1740                    snapshot.buffer_rows(fold_row).collect::<Vec<_>>(),
1741                    expected_buffer_rows[(fold_row as usize)..],
1742                    "wrong buffer rows starting at fold row {}",
1743                    fold_row,
1744                );
1745                fold_row += 1;
1746            }
1747
1748            let folded_buffer_rows = map
1749                .merged_folds()
1750                .iter()
1751                .flat_map(|fold_range| {
1752                    let start_row = fold_range.start.to_point(&buffer_snapshot).row;
1753                    let end = fold_range.end.to_point(&buffer_snapshot);
1754                    if end.column == 0 {
1755                        start_row..end.row
1756                    } else {
1757                        start_row..end.row + 1
1758                    }
1759                })
1760                .collect::<HashSet<_>>();
1761            for row in 0..=buffer_snapshot.max_point().row {
1762                assert_eq!(
1763                    snapshot.is_line_folded(MultiBufferRow(row)),
1764                    folded_buffer_rows.contains(&row),
1765                    "expected buffer row {}{} to be folded",
1766                    row,
1767                    if folded_buffer_rows.contains(&row) {
1768                        ""
1769                    } else {
1770                        " not"
1771                    }
1772                );
1773            }
1774
1775            for _ in 0..5 {
1776                let end =
1777                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1778                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1779                let expected_folds = map
1780                    .snapshot
1781                    .folds
1782                    .items(&buffer_snapshot)
1783                    .into_iter()
1784                    .filter(|fold| {
1785                        let start = buffer_snapshot.anchor_before(start);
1786                        let end = buffer_snapshot.anchor_after(end);
1787                        start.cmp(&fold.range.end, &buffer_snapshot) == Ordering::Less
1788                            && end.cmp(&fold.range.start, &buffer_snapshot) == Ordering::Greater
1789                    })
1790                    .collect::<Vec<_>>();
1791
1792                assert_eq!(
1793                    snapshot
1794                        .folds_in_range(start..end)
1795                        .cloned()
1796                        .collect::<Vec<_>>(),
1797                    expected_folds
1798                );
1799            }
1800
1801            let text = snapshot.text();
1802            for _ in 0..5 {
1803                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1804                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1805                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1806                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1807                let mut start =
1808                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1809                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1810                if start > end {
1811                    mem::swap(&mut start, &mut end);
1812                }
1813
1814                let lines = start..end;
1815                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1816                assert_eq!(
1817                    snapshot.text_summary_for_range(lines),
1818                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1819                )
1820            }
1821
1822            let mut text = initial_snapshot.text();
1823            for (snapshot, edits) in snapshot_edits.drain(..) {
1824                let new_text = snapshot.text();
1825                for edit in edits {
1826                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
1827                    let new_bytes = edit.new.start.0..edit.new.end.0;
1828                    text.replace_range(old_bytes, &new_text[new_bytes]);
1829                }
1830
1831                assert_eq!(text, new_text);
1832                initial_snapshot = snapshot;
1833            }
1834        }
1835    }
1836
1837    #[gpui::test]
1838    fn test_buffer_rows(cx: &mut gpui::AppContext) {
1839        let text = sample_text(6, 6, 'a') + "\n";
1840        let buffer = MultiBuffer::build_simple(&text, cx);
1841
1842        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1843        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1844        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1845
1846        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1847        writer.fold(vec![
1848            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1849            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1850        ]);
1851
1852        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1853        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee\nffffff\n");
1854        assert_eq!(
1855            snapshot.buffer_rows(0).collect::<Vec<_>>(),
1856            [Some(0), Some(3), Some(5), Some(6)]
1857        );
1858        assert_eq!(snapshot.buffer_rows(3).collect::<Vec<_>>(), [Some(6)]);
1859    }
1860
1861    fn init_test(cx: &mut gpui::AppContext) {
1862        let store = SettingsStore::test(cx);
1863        cx.set_global(store);
1864    }
1865
1866    impl FoldMap {
1867        fn merged_folds(&self) -> Vec<Range<usize>> {
1868            let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
1869            let buffer = &inlay_snapshot.buffer;
1870            let mut folds = self.snapshot.folds.items(buffer);
1871            // Ensure sorting doesn't change how folds get merged and displayed.
1872            folds.sort_by(|a, b| a.range.cmp(&b.range, buffer));
1873            let mut folds = folds
1874                .iter()
1875                .map(|fold| fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer))
1876                .peekable();
1877
1878            let mut merged_folds = Vec::new();
1879            while let Some(mut fold_range) = folds.next() {
1880                while let Some(next_range) = folds.peek() {
1881                    if fold_range.end >= next_range.start {
1882                        if next_range.end > fold_range.end {
1883                            fold_range.end = next_range.end;
1884                        }
1885                        folds.next();
1886                    } else {
1887                        break;
1888                    }
1889                }
1890                if fold_range.end > fold_range.start {
1891                    merged_folds.push(fold_range);
1892                }
1893            }
1894            merged_folds
1895        }
1896
1897        pub fn randomly_mutate(
1898            &mut self,
1899            rng: &mut impl Rng,
1900        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
1901            let mut snapshot_edits = Vec::new();
1902            match rng.gen_range(0..=100) {
1903                0..=39 if !self.snapshot.folds.is_empty() => {
1904                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
1905                    let buffer = &inlay_snapshot.buffer;
1906                    let mut to_unfold = Vec::new();
1907                    for _ in 0..rng.gen_range(1..=3) {
1908                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1909                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1910                        to_unfold.push(start..end);
1911                    }
1912                    let inclusive = rng.gen();
1913                    log::info!("unfolding {:?} (inclusive: {})", to_unfold, inclusive);
1914                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
1915                    snapshot_edits.push((snapshot, edits));
1916                    let (snapshot, edits) = writer.unfold(to_unfold, inclusive);
1917                    snapshot_edits.push((snapshot, edits));
1918                }
1919                _ => {
1920                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
1921                    let buffer = &inlay_snapshot.buffer;
1922                    let mut to_fold = Vec::new();
1923                    for _ in 0..rng.gen_range(1..=2) {
1924                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
1925                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
1926                        to_fold.push((start..end, FoldPlaceholder::test()));
1927                    }
1928                    log::info!("folding {:?}", to_fold);
1929                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
1930                    snapshot_edits.push((snapshot, edits));
1931                    let (snapshot, edits) = writer.fold(to_fold);
1932                    snapshot_edits.push((snapshot, edits));
1933                }
1934            }
1935            snapshot_edits
1936        }
1937    }
1938}