1use super::{
   2    Highlights,
   3    inlay_map::{InlayBufferRows, InlayChunks, InlayEdit, InlayOffset, InlayPoint, InlaySnapshot},
   4};
   5use gpui::{AnyElement, App, ElementId, HighlightStyle, Pixels, Window};
   6use language::{Edit, HighlightId, Point, TextSummary};
   7use multi_buffer::{
   8    Anchor, AnchorRangeExt, MultiBufferRow, MultiBufferSnapshot, RowInfo, ToOffset,
   9};
  10use std::{
  11    any::TypeId,
  12    cmp::{self, Ordering},
  13    fmt, iter,
  14    ops::{Add, AddAssign, Deref, DerefMut, Range, Sub},
  15    sync::Arc,
  16    usize,
  17};
  18use sum_tree::{Bias, Cursor, FilterCursor, SumTree, Summary, TreeMap};
  19use ui::IntoElement as _;
  20use util::post_inc;
  21
  22#[derive(Clone)]
  23pub struct FoldPlaceholder {
  24    /// Creates an element to represent this fold's placeholder.
  25    pub render: Arc<dyn Send + Sync + Fn(FoldId, Range<Anchor>, &mut App) -> AnyElement>,
  26    /// If true, the element is constrained to the shaped width of an ellipsis.
  27    pub constrain_width: bool,
  28    /// If true, merges the fold with an adjacent one.
  29    pub merge_adjacent: bool,
  30    /// Category of the fold. Useful for carefully removing from overlapping folds.
  31    pub type_tag: Option<TypeId>,
  32}
  33
  34impl Default for FoldPlaceholder {
  35    fn default() -> Self {
  36        Self {
  37            render: Arc::new(|_, _, _| gpui::Empty.into_any_element()),
  38            constrain_width: true,
  39            merge_adjacent: true,
  40            type_tag: None,
  41        }
  42    }
  43}
  44
  45impl FoldPlaceholder {
  46    #[cfg(any(test, feature = "test-support"))]
  47    pub fn test() -> Self {
  48        Self {
  49            render: Arc::new(|_id, _range, _cx| gpui::Empty.into_any_element()),
  50            constrain_width: true,
  51            merge_adjacent: true,
  52            type_tag: None,
  53        }
  54    }
  55}
  56
  57impl fmt::Debug for FoldPlaceholder {
  58    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  59        f.debug_struct("FoldPlaceholder")
  60            .field("constrain_width", &self.constrain_width)
  61            .finish()
  62    }
  63}
  64
  65impl Eq for FoldPlaceholder {}
  66
  67impl PartialEq for FoldPlaceholder {
  68    fn eq(&self, other: &Self) -> bool {
  69        Arc::ptr_eq(&self.render, &other.render) && self.constrain_width == other.constrain_width
  70    }
  71}
  72
  73#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  74pub struct FoldPoint(pub Point);
  75
  76impl FoldPoint {
  77    pub fn new(row: u32, column: u32) -> Self {
  78        Self(Point::new(row, column))
  79    }
  80
  81    pub fn row(self) -> u32 {
  82        self.0.row
  83    }
  84
  85    pub fn column(self) -> u32 {
  86        self.0.column
  87    }
  88
  89    pub fn row_mut(&mut self) -> &mut u32 {
  90        &mut self.0.row
  91    }
  92
  93    #[cfg(test)]
  94    pub fn column_mut(&mut self) -> &mut u32 {
  95        &mut self.0.column
  96    }
  97
  98    pub fn to_inlay_point(self, snapshot: &FoldSnapshot) -> InlayPoint {
  99        let mut cursor = snapshot.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 100        cursor.seek(&self, Bias::Right, &());
 101        let overshoot = self.0 - cursor.start().0.0;
 102        InlayPoint(cursor.start().1.0 + overshoot)
 103    }
 104
 105    pub fn to_offset(self, snapshot: &FoldSnapshot) -> FoldOffset {
 106        let mut cursor = snapshot
 107            .transforms
 108            .cursor::<(FoldPoint, TransformSummary)>(&());
 109        cursor.seek(&self, Bias::Right, &());
 110        let overshoot = self.0 - cursor.start().1.output.lines;
 111        let mut offset = cursor.start().1.output.len;
 112        if !overshoot.is_zero() {
 113            let transform = cursor.item().expect("display point out of range");
 114            assert!(transform.placeholder.is_none());
 115            let end_inlay_offset = snapshot
 116                .inlay_snapshot
 117                .to_offset(InlayPoint(cursor.start().1.input.lines + overshoot));
 118            offset += end_inlay_offset.0 - cursor.start().1.input.len;
 119        }
 120        FoldOffset(offset)
 121    }
 122}
 123
 124impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
 125    fn zero(_cx: &()) -> Self {
 126        Default::default()
 127    }
 128
 129    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
 130        self.0 += &summary.output.lines;
 131    }
 132}
 133
 134pub(crate) struct FoldMapWriter<'a>(&'a mut FoldMap);
 135
 136impl FoldMapWriter<'_> {
 137    pub(crate) fn fold<T: ToOffset>(
 138        &mut self,
 139        ranges: impl IntoIterator<Item = (Range<T>, FoldPlaceholder)>,
 140    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 141        let mut edits = Vec::new();
 142        let mut folds = Vec::new();
 143        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 144        for (range, fold_text) in ranges.into_iter() {
 145            let buffer = &snapshot.buffer;
 146            let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 147
 148            // Ignore any empty ranges.
 149            if range.start == range.end {
 150                continue;
 151            }
 152
 153            // For now, ignore any ranges that span an excerpt boundary.
 154            let fold_range =
 155                FoldRange(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 156            if fold_range.0.start.excerpt_id != fold_range.0.end.excerpt_id {
 157                continue;
 158            }
 159
 160            folds.push(Fold {
 161                id: FoldId(post_inc(&mut self.0.next_fold_id.0)),
 162                range: fold_range,
 163                placeholder: fold_text,
 164            });
 165
 166            let inlay_range =
 167                snapshot.to_inlay_offset(range.start)..snapshot.to_inlay_offset(range.end);
 168            edits.push(InlayEdit {
 169                old: inlay_range.clone(),
 170                new: inlay_range,
 171            });
 172        }
 173
 174        let buffer = &snapshot.buffer;
 175        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(&a.range, &b.range, buffer));
 176
 177        self.0.snapshot.folds = {
 178            let mut new_tree = SumTree::new(buffer);
 179            let mut cursor = self.0.snapshot.folds.cursor::<FoldRange>(buffer);
 180            for fold in folds {
 181                self.0.snapshot.fold_metadata_by_id.insert(
 182                    fold.id,
 183                    FoldMetadata {
 184                        range: fold.range.clone(),
 185                        width: None,
 186                    },
 187                );
 188                new_tree.append(cursor.slice(&fold.range, Bias::Right, buffer), buffer);
 189                new_tree.push(fold, buffer);
 190            }
 191            new_tree.append(cursor.suffix(buffer), buffer);
 192            new_tree
 193        };
 194
 195        let edits = consolidate_inlay_edits(edits);
 196        let edits = self.0.sync(snapshot.clone(), edits);
 197        (self.0.snapshot.clone(), edits)
 198    }
 199
 200    /// Removes any folds with the given ranges.
 201    pub(crate) fn remove_folds<T: ToOffset>(
 202        &mut self,
 203        ranges: impl IntoIterator<Item = Range<T>>,
 204        type_id: TypeId,
 205    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 206        self.remove_folds_with(
 207            ranges,
 208            |fold| fold.placeholder.type_tag == Some(type_id),
 209            false,
 210        )
 211    }
 212
 213    /// Removes any folds whose ranges intersect the given ranges.
 214    pub(crate) fn unfold_intersecting<T: ToOffset>(
 215        &mut self,
 216        ranges: impl IntoIterator<Item = Range<T>>,
 217        inclusive: bool,
 218    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 219        self.remove_folds_with(ranges, |_| true, inclusive)
 220    }
 221
 222    /// Removes any folds that intersect the given ranges and for which the given predicate
 223    /// returns true.
 224    fn remove_folds_with<T: ToOffset>(
 225        &mut self,
 226        ranges: impl IntoIterator<Item = Range<T>>,
 227        should_unfold: impl Fn(&Fold) -> bool,
 228        inclusive: bool,
 229    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 230        let mut edits = Vec::new();
 231        let mut fold_ixs_to_delete = Vec::new();
 232        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 233        let buffer = &snapshot.buffer;
 234        for range in ranges.into_iter() {
 235            let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 236            let mut folds_cursor =
 237                intersecting_folds(&snapshot, &self.0.snapshot.folds, range.clone(), inclusive);
 238            while let Some(fold) = folds_cursor.item() {
 239                let offset_range =
 240                    fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer);
 241                if should_unfold(fold) {
 242                    if offset_range.end > offset_range.start {
 243                        let inlay_range = snapshot.to_inlay_offset(offset_range.start)
 244                            ..snapshot.to_inlay_offset(offset_range.end);
 245                        edits.push(InlayEdit {
 246                            old: inlay_range.clone(),
 247                            new: inlay_range,
 248                        });
 249                    }
 250                    fold_ixs_to_delete.push(*folds_cursor.start());
 251                    self.0.snapshot.fold_metadata_by_id.remove(&fold.id);
 252                }
 253                folds_cursor.next(buffer);
 254            }
 255        }
 256
 257        fold_ixs_to_delete.sort_unstable();
 258        fold_ixs_to_delete.dedup();
 259
 260        self.0.snapshot.folds = {
 261            let mut cursor = self.0.snapshot.folds.cursor::<usize>(buffer);
 262            let mut folds = SumTree::new(buffer);
 263            for fold_ix in fold_ixs_to_delete {
 264                folds.append(cursor.slice(&fold_ix, Bias::Right, buffer), buffer);
 265                cursor.next(buffer);
 266            }
 267            folds.append(cursor.suffix(buffer), buffer);
 268            folds
 269        };
 270
 271        let edits = consolidate_inlay_edits(edits);
 272        let edits = self.0.sync(snapshot.clone(), edits);
 273        (self.0.snapshot.clone(), edits)
 274    }
 275
 276    pub(crate) fn update_fold_widths(
 277        &mut self,
 278        new_widths: impl IntoIterator<Item = (FoldId, Pixels)>,
 279    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 280        let mut edits = Vec::new();
 281        let inlay_snapshot = self.0.snapshot.inlay_snapshot.clone();
 282        let buffer = &inlay_snapshot.buffer;
 283
 284        for (id, new_width) in new_widths {
 285            if let Some(metadata) = self.0.snapshot.fold_metadata_by_id.get(&id).cloned() {
 286                if Some(new_width) != metadata.width {
 287                    let buffer_start = metadata.range.start.to_offset(buffer);
 288                    let buffer_end = metadata.range.end.to_offset(buffer);
 289                    let inlay_range = inlay_snapshot.to_inlay_offset(buffer_start)
 290                        ..inlay_snapshot.to_inlay_offset(buffer_end);
 291                    edits.push(InlayEdit {
 292                        old: inlay_range.clone(),
 293                        new: inlay_range.clone(),
 294                    });
 295
 296                    self.0.snapshot.fold_metadata_by_id.insert(
 297                        id,
 298                        FoldMetadata {
 299                            range: metadata.range,
 300                            width: Some(new_width),
 301                        },
 302                    );
 303                }
 304            }
 305        }
 306
 307        let edits = consolidate_inlay_edits(edits);
 308        let edits = self.0.sync(inlay_snapshot, edits);
 309        (self.0.snapshot.clone(), edits)
 310    }
 311}
 312
 313/// Decides where the fold indicators should be; also tracks parts of a source file that are currently folded.
 314///
 315/// See the [`display_map` module documentation](crate::display_map) for more information.
 316pub(crate) struct FoldMap {
 317    snapshot: FoldSnapshot,
 318    next_fold_id: FoldId,
 319}
 320
 321impl FoldMap {
 322    pub(crate) fn new(inlay_snapshot: InlaySnapshot) -> (Self, FoldSnapshot) {
 323        let this = Self {
 324            snapshot: FoldSnapshot {
 325                folds: SumTree::new(&inlay_snapshot.buffer),
 326                transforms: SumTree::from_item(
 327                    Transform {
 328                        summary: TransformSummary {
 329                            input: inlay_snapshot.text_summary(),
 330                            output: inlay_snapshot.text_summary(),
 331                        },
 332                        placeholder: None,
 333                    },
 334                    &(),
 335                ),
 336                inlay_snapshot: inlay_snapshot.clone(),
 337                version: 0,
 338                fold_metadata_by_id: TreeMap::default(),
 339            },
 340            next_fold_id: FoldId::default(),
 341        };
 342        let snapshot = this.snapshot.clone();
 343        (this, snapshot)
 344    }
 345
 346    pub fn read(
 347        &mut self,
 348        inlay_snapshot: InlaySnapshot,
 349        edits: Vec<InlayEdit>,
 350    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 351        let edits = self.sync(inlay_snapshot, edits);
 352        self.check_invariants();
 353        (self.snapshot.clone(), edits)
 354    }
 355
 356    pub fn write(
 357        &mut self,
 358        inlay_snapshot: InlaySnapshot,
 359        edits: Vec<InlayEdit>,
 360    ) -> (FoldMapWriter, FoldSnapshot, Vec<FoldEdit>) {
 361        let (snapshot, edits) = self.read(inlay_snapshot, edits);
 362        (FoldMapWriter(self), snapshot, edits)
 363    }
 364
 365    fn check_invariants(&self) {
 366        if cfg!(test) {
 367            assert_eq!(
 368                self.snapshot.transforms.summary().input.len,
 369                self.snapshot.inlay_snapshot.len().0,
 370                "transform tree does not match inlay snapshot's length"
 371            );
 372
 373            let mut prev_transform_isomorphic = false;
 374            for transform in self.snapshot.transforms.iter() {
 375                if !transform.is_fold() && prev_transform_isomorphic {
 376                    panic!(
 377                        "found adjacent isomorphic transforms: {:?}",
 378                        self.snapshot.transforms.items(&())
 379                    );
 380                }
 381                prev_transform_isomorphic = !transform.is_fold();
 382            }
 383
 384            let mut folds = self.snapshot.folds.iter().peekable();
 385            while let Some(fold) = folds.next() {
 386                if let Some(next_fold) = folds.peek() {
 387                    let comparison = fold.range.cmp(&next_fold.range, self.snapshot.buffer());
 388                    assert!(comparison.is_le());
 389                }
 390            }
 391        }
 392    }
 393
 394    fn sync(
 395        &mut self,
 396        inlay_snapshot: InlaySnapshot,
 397        inlay_edits: Vec<InlayEdit>,
 398    ) -> Vec<FoldEdit> {
 399        if inlay_edits.is_empty() {
 400            if self.snapshot.inlay_snapshot.version != inlay_snapshot.version {
 401                self.snapshot.version += 1;
 402            }
 403            self.snapshot.inlay_snapshot = inlay_snapshot;
 404            Vec::new()
 405        } else {
 406            let mut inlay_edits_iter = inlay_edits.iter().cloned().peekable();
 407
 408            let mut new_transforms = SumTree::<Transform>::default();
 409            let mut cursor = self.snapshot.transforms.cursor::<InlayOffset>(&());
 410            cursor.seek(&InlayOffset(0), Bias::Right, &());
 411
 412            while let Some(mut edit) = inlay_edits_iter.next() {
 413                if let Some(item) = cursor.item() {
 414                    if !item.is_fold() {
 415                        new_transforms.update_last(
 416                            |transform| {
 417                                if !transform.is_fold() {
 418                                    transform.summary.add_summary(&item.summary, &());
 419                                    cursor.next(&());
 420                                }
 421                            },
 422                            &(),
 423                        );
 424                    }
 425                }
 426                new_transforms.append(cursor.slice(&edit.old.start, Bias::Left, &()), &());
 427                edit.new.start -= edit.old.start - *cursor.start();
 428                edit.old.start = *cursor.start();
 429
 430                cursor.seek(&edit.old.end, Bias::Right, &());
 431                cursor.next(&());
 432
 433                let mut delta = edit.new_len().0 as isize - edit.old_len().0 as isize;
 434                loop {
 435                    edit.old.end = *cursor.start();
 436
 437                    if let Some(next_edit) = inlay_edits_iter.peek() {
 438                        if next_edit.old.start > edit.old.end {
 439                            break;
 440                        }
 441
 442                        let next_edit = inlay_edits_iter.next().unwrap();
 443                        delta += next_edit.new_len().0 as isize - next_edit.old_len().0 as isize;
 444
 445                        if next_edit.old.end >= edit.old.end {
 446                            edit.old.end = next_edit.old.end;
 447                            cursor.seek(&edit.old.end, Bias::Right, &());
 448                            cursor.next(&());
 449                        }
 450                    } else {
 451                        break;
 452                    }
 453                }
 454
 455                edit.new.end =
 456                    InlayOffset(((edit.new.start + edit.old_len()).0 as isize + delta) as usize);
 457
 458                let anchor = inlay_snapshot
 459                    .buffer
 460                    .anchor_before(inlay_snapshot.to_buffer_offset(edit.new.start));
 461                let mut folds_cursor = self
 462                    .snapshot
 463                    .folds
 464                    .cursor::<FoldRange>(&inlay_snapshot.buffer);
 465                folds_cursor.seek(
 466                    &FoldRange(anchor..Anchor::max()),
 467                    Bias::Left,
 468                    &inlay_snapshot.buffer,
 469                );
 470
 471                let mut folds = iter::from_fn({
 472                    let inlay_snapshot = &inlay_snapshot;
 473                    move || {
 474                        let item = folds_cursor.item().map(|fold| {
 475                            let buffer_start = fold.range.start.to_offset(&inlay_snapshot.buffer);
 476                            let buffer_end = fold.range.end.to_offset(&inlay_snapshot.buffer);
 477                            (
 478                                fold.clone(),
 479                                inlay_snapshot.to_inlay_offset(buffer_start)
 480                                    ..inlay_snapshot.to_inlay_offset(buffer_end),
 481                            )
 482                        });
 483                        folds_cursor.next(&inlay_snapshot.buffer);
 484                        item
 485                    }
 486                })
 487                .peekable();
 488
 489                while folds
 490                    .peek()
 491                    .map_or(false, |(_, fold_range)| fold_range.start < edit.new.end)
 492                {
 493                    let (fold, mut fold_range) = folds.next().unwrap();
 494                    let sum = new_transforms.summary();
 495
 496                    assert!(fold_range.start.0 >= sum.input.len);
 497
 498                    while folds.peek().map_or(false, |(next_fold, next_fold_range)| {
 499                        next_fold_range.start < fold_range.end
 500                            || (next_fold_range.start == fold_range.end
 501                                && fold.placeholder.merge_adjacent
 502                                && next_fold.placeholder.merge_adjacent)
 503                    }) {
 504                        let (_, next_fold_range) = folds.next().unwrap();
 505                        if next_fold_range.end > fold_range.end {
 506                            fold_range.end = next_fold_range.end;
 507                        }
 508                    }
 509
 510                    if fold_range.start.0 > sum.input.len {
 511                        let text_summary = inlay_snapshot
 512                            .text_summary_for_range(InlayOffset(sum.input.len)..fold_range.start);
 513                        push_isomorphic(&mut new_transforms, text_summary);
 514                    }
 515
 516                    if fold_range.end > fold_range.start {
 517                        const ELLIPSIS: &str = "⋯";
 518
 519                        let fold_id = fold.id;
 520                        new_transforms.push(
 521                            Transform {
 522                                summary: TransformSummary {
 523                                    output: TextSummary::from(ELLIPSIS),
 524                                    input: inlay_snapshot
 525                                        .text_summary_for_range(fold_range.start..fold_range.end),
 526                                },
 527                                placeholder: Some(TransformPlaceholder {
 528                                    text: ELLIPSIS,
 529                                    renderer: ChunkRenderer {
 530                                        id: fold.id,
 531                                        render: Arc::new(move |cx| {
 532                                            (fold.placeholder.render)(
 533                                                fold_id,
 534                                                fold.range.0.clone(),
 535                                                cx.context,
 536                                            )
 537                                        }),
 538                                        constrain_width: fold.placeholder.constrain_width,
 539                                        measured_width: self.snapshot.fold_width(&fold_id),
 540                                    },
 541                                }),
 542                            },
 543                            &(),
 544                        );
 545                    }
 546                }
 547
 548                let sum = new_transforms.summary();
 549                if sum.input.len < edit.new.end.0 {
 550                    let text_summary = inlay_snapshot
 551                        .text_summary_for_range(InlayOffset(sum.input.len)..edit.new.end);
 552                    push_isomorphic(&mut new_transforms, text_summary);
 553                }
 554            }
 555
 556            new_transforms.append(cursor.suffix(&()), &());
 557            if new_transforms.is_empty() {
 558                let text_summary = inlay_snapshot.text_summary();
 559                push_isomorphic(&mut new_transforms, text_summary);
 560            }
 561
 562            drop(cursor);
 563
 564            let mut fold_edits = Vec::with_capacity(inlay_edits.len());
 565            {
 566                let mut old_transforms = self
 567                    .snapshot
 568                    .transforms
 569                    .cursor::<(InlayOffset, FoldOffset)>(&());
 570                let mut new_transforms = new_transforms.cursor::<(InlayOffset, FoldOffset)>(&());
 571
 572                for mut edit in inlay_edits {
 573                    old_transforms.seek(&edit.old.start, Bias::Left, &());
 574                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 575                        edit.old.start = old_transforms.start().0;
 576                    }
 577                    let old_start =
 578                        old_transforms.start().1.0 + (edit.old.start - old_transforms.start().0).0;
 579
 580                    old_transforms.seek_forward(&edit.old.end, Bias::Right, &());
 581                    if old_transforms.item().map_or(false, |t| t.is_fold()) {
 582                        old_transforms.next(&());
 583                        edit.old.end = old_transforms.start().0;
 584                    }
 585                    let old_end =
 586                        old_transforms.start().1.0 + (edit.old.end - old_transforms.start().0).0;
 587
 588                    new_transforms.seek(&edit.new.start, Bias::Left, &());
 589                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 590                        edit.new.start = new_transforms.start().0;
 591                    }
 592                    let new_start =
 593                        new_transforms.start().1.0 + (edit.new.start - new_transforms.start().0).0;
 594
 595                    new_transforms.seek_forward(&edit.new.end, Bias::Right, &());
 596                    if new_transforms.item().map_or(false, |t| t.is_fold()) {
 597                        new_transforms.next(&());
 598                        edit.new.end = new_transforms.start().0;
 599                    }
 600                    let new_end =
 601                        new_transforms.start().1.0 + (edit.new.end - new_transforms.start().0).0;
 602
 603                    fold_edits.push(FoldEdit {
 604                        old: FoldOffset(old_start)..FoldOffset(old_end),
 605                        new: FoldOffset(new_start)..FoldOffset(new_end),
 606                    });
 607                }
 608
 609                fold_edits = consolidate_fold_edits(fold_edits);
 610            }
 611
 612            self.snapshot.transforms = new_transforms;
 613            self.snapshot.inlay_snapshot = inlay_snapshot;
 614            self.snapshot.version += 1;
 615            fold_edits
 616        }
 617    }
 618}
 619
 620#[derive(Clone)]
 621pub struct FoldSnapshot {
 622    transforms: SumTree<Transform>,
 623    folds: SumTree<Fold>,
 624    fold_metadata_by_id: TreeMap<FoldId, FoldMetadata>,
 625    pub inlay_snapshot: InlaySnapshot,
 626    pub version: usize,
 627}
 628
 629impl FoldSnapshot {
 630    pub fn buffer(&self) -> &MultiBufferSnapshot {
 631        &self.inlay_snapshot.buffer
 632    }
 633
 634    fn fold_width(&self, fold_id: &FoldId) -> Option<Pixels> {
 635        self.fold_metadata_by_id.get(fold_id)?.width
 636    }
 637
 638    #[cfg(test)]
 639    pub fn text(&self) -> String {
 640        self.chunks(FoldOffset(0)..self.len(), false, Highlights::default())
 641            .map(|c| c.text)
 642            .collect()
 643    }
 644
 645    #[cfg(test)]
 646    pub fn fold_count(&self) -> usize {
 647        self.folds.items(&self.inlay_snapshot.buffer).len()
 648    }
 649
 650    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
 651        let mut summary = TextSummary::default();
 652
 653        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 654        cursor.seek(&range.start, Bias::Right, &());
 655        if let Some(transform) = cursor.item() {
 656            let start_in_transform = range.start.0 - cursor.start().0.0;
 657            let end_in_transform = cmp::min(range.end, cursor.end(&()).0).0 - cursor.start().0.0;
 658            if let Some(placeholder) = transform.placeholder.as_ref() {
 659                summary = TextSummary::from(
 660                    &placeholder.text
 661                        [start_in_transform.column as usize..end_in_transform.column as usize],
 662                );
 663            } else {
 664                let inlay_start = self
 665                    .inlay_snapshot
 666                    .to_offset(InlayPoint(cursor.start().1.0 + start_in_transform));
 667                let inlay_end = self
 668                    .inlay_snapshot
 669                    .to_offset(InlayPoint(cursor.start().1.0 + end_in_transform));
 670                summary = self
 671                    .inlay_snapshot
 672                    .text_summary_for_range(inlay_start..inlay_end);
 673            }
 674        }
 675
 676        if range.end > cursor.end(&()).0 {
 677            cursor.next(&());
 678            summary += &cursor
 679                .summary::<_, TransformSummary>(&range.end, Bias::Right, &())
 680                .output;
 681            if let Some(transform) = cursor.item() {
 682                let end_in_transform = range.end.0 - cursor.start().0.0;
 683                if let Some(placeholder) = transform.placeholder.as_ref() {
 684                    summary +=
 685                        TextSummary::from(&placeholder.text[..end_in_transform.column as usize]);
 686                } else {
 687                    let inlay_start = self.inlay_snapshot.to_offset(cursor.start().1);
 688                    let inlay_end = self
 689                        .inlay_snapshot
 690                        .to_offset(InlayPoint(cursor.start().1.0 + end_in_transform));
 691                    summary += self
 692                        .inlay_snapshot
 693                        .text_summary_for_range(inlay_start..inlay_end);
 694                }
 695            }
 696        }
 697
 698        summary
 699    }
 700
 701    pub fn to_fold_point(&self, point: InlayPoint, bias: Bias) -> FoldPoint {
 702        let mut cursor = self.transforms.cursor::<(InlayPoint, FoldPoint)>(&());
 703        cursor.seek(&point, Bias::Right, &());
 704        if cursor.item().map_or(false, |t| t.is_fold()) {
 705            if bias == Bias::Left || point == cursor.start().0 {
 706                cursor.start().1
 707            } else {
 708                cursor.end(&()).1
 709            }
 710        } else {
 711            let overshoot = point.0 - cursor.start().0.0;
 712            FoldPoint(cmp::min(
 713                cursor.start().1.0 + overshoot,
 714                cursor.end(&()).1.0,
 715            ))
 716        }
 717    }
 718
 719    pub fn len(&self) -> FoldOffset {
 720        FoldOffset(self.transforms.summary().output.len)
 721    }
 722
 723    pub fn line_len(&self, row: u32) -> u32 {
 724        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 725        let line_end = if row >= self.max_point().row() {
 726            self.len().0
 727        } else {
 728            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 729        };
 730        (line_end - line_start) as u32
 731    }
 732
 733    pub fn row_infos(&self, start_row: u32) -> FoldRows {
 734        if start_row > self.transforms.summary().output.lines.row {
 735            panic!("invalid display row {}", start_row);
 736        }
 737
 738        let fold_point = FoldPoint::new(start_row, 0);
 739        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 740        cursor.seek(&fold_point, Bias::Left, &());
 741
 742        let overshoot = fold_point.0 - cursor.start().0.0;
 743        let inlay_point = InlayPoint(cursor.start().1.0 + overshoot);
 744        let input_rows = self.inlay_snapshot.row_infos(inlay_point.row());
 745
 746        FoldRows {
 747            fold_point,
 748            input_rows,
 749            cursor,
 750        }
 751    }
 752
 753    pub fn max_point(&self) -> FoldPoint {
 754        FoldPoint(self.transforms.summary().output.lines)
 755    }
 756
 757    #[cfg(test)]
 758    pub fn longest_row(&self) -> u32 {
 759        self.transforms.summary().output.longest_row
 760    }
 761
 762    pub fn folds_in_range<T>(&self, range: Range<T>) -> impl Iterator<Item = &Fold>
 763    where
 764        T: ToOffset,
 765    {
 766        let buffer = &self.inlay_snapshot.buffer;
 767        let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 768        let mut folds = intersecting_folds(&self.inlay_snapshot, &self.folds, range, false);
 769        iter::from_fn(move || {
 770            let item = folds.item();
 771            folds.next(&self.inlay_snapshot.buffer);
 772            item
 773        })
 774    }
 775
 776    pub fn intersects_fold<T>(&self, offset: T) -> bool
 777    where
 778        T: ToOffset,
 779    {
 780        let buffer_offset = offset.to_offset(&self.inlay_snapshot.buffer);
 781        let inlay_offset = self.inlay_snapshot.to_inlay_offset(buffer_offset);
 782        let mut cursor = self.transforms.cursor::<InlayOffset>(&());
 783        cursor.seek(&inlay_offset, Bias::Right, &());
 784        cursor.item().map_or(false, |t| t.placeholder.is_some())
 785    }
 786
 787    pub fn is_line_folded(&self, buffer_row: MultiBufferRow) -> bool {
 788        let mut inlay_point = self
 789            .inlay_snapshot
 790            .to_inlay_point(Point::new(buffer_row.0, 0));
 791        let mut cursor = self.transforms.cursor::<InlayPoint>(&());
 792        cursor.seek(&inlay_point, Bias::Right, &());
 793        loop {
 794            match cursor.item() {
 795                Some(transform) => {
 796                    let buffer_point = self.inlay_snapshot.to_buffer_point(inlay_point);
 797                    if buffer_point.row != buffer_row.0 {
 798                        return false;
 799                    } else if transform.placeholder.is_some() {
 800                        return true;
 801                    }
 802                }
 803                None => return false,
 804            }
 805
 806            if cursor.end(&()).row() == inlay_point.row() {
 807                cursor.next(&());
 808            } else {
 809                inlay_point.0 += Point::new(1, 0);
 810                cursor.seek(&inlay_point, Bias::Right, &());
 811            }
 812        }
 813    }
 814
 815    pub(crate) fn chunks<'a>(
 816        &'a self,
 817        range: Range<FoldOffset>,
 818        language_aware: bool,
 819        highlights: Highlights<'a>,
 820    ) -> FoldChunks<'a> {
 821        let mut transform_cursor = self.transforms.cursor::<(FoldOffset, InlayOffset)>(&());
 822        transform_cursor.seek(&range.start, Bias::Right, &());
 823
 824        let inlay_start = {
 825            let overshoot = range.start.0 - transform_cursor.start().0.0;
 826            transform_cursor.start().1 + InlayOffset(overshoot)
 827        };
 828
 829        let transform_end = transform_cursor.end(&());
 830
 831        let inlay_end = if transform_cursor
 832            .item()
 833            .map_or(true, |transform| transform.is_fold())
 834        {
 835            inlay_start
 836        } else if range.end < transform_end.0 {
 837            let overshoot = range.end.0 - transform_cursor.start().0.0;
 838            transform_cursor.start().1 + InlayOffset(overshoot)
 839        } else {
 840            transform_end.1
 841        };
 842
 843        FoldChunks {
 844            transform_cursor,
 845            inlay_chunks: self.inlay_snapshot.chunks(
 846                inlay_start..inlay_end,
 847                language_aware,
 848                highlights,
 849            ),
 850            inlay_chunk: None,
 851            inlay_offset: inlay_start,
 852            output_offset: range.start,
 853            max_output_offset: range.end,
 854        }
 855    }
 856
 857    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 858        self.chunks(
 859            start.to_offset(self)..self.len(),
 860            false,
 861            Highlights::default(),
 862        )
 863        .flat_map(|chunk| chunk.text.chars())
 864    }
 865
 866    #[cfg(test)]
 867    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 868        if offset > self.len() {
 869            self.len()
 870        } else {
 871            self.clip_point(offset.to_point(self), bias).to_offset(self)
 872        }
 873    }
 874
 875    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 876        let mut cursor = self.transforms.cursor::<(FoldPoint, InlayPoint)>(&());
 877        cursor.seek(&point, Bias::Right, &());
 878        if let Some(transform) = cursor.item() {
 879            let transform_start = cursor.start().0.0;
 880            if transform.placeholder.is_some() {
 881                if point.0 == transform_start || matches!(bias, Bias::Left) {
 882                    FoldPoint(transform_start)
 883                } else {
 884                    FoldPoint(cursor.end(&()).0.0)
 885                }
 886            } else {
 887                let overshoot = InlayPoint(point.0 - transform_start);
 888                let inlay_point = cursor.start().1 + overshoot;
 889                let clipped_inlay_point = self.inlay_snapshot.clip_point(inlay_point, bias);
 890                FoldPoint(cursor.start().0.0 + (clipped_inlay_point - cursor.start().1).0)
 891            }
 892        } else {
 893            FoldPoint(self.transforms.summary().output.lines)
 894        }
 895    }
 896}
 897
 898fn push_isomorphic(transforms: &mut SumTree<Transform>, summary: TextSummary) {
 899    let mut did_merge = false;
 900    transforms.update_last(
 901        |last| {
 902            if !last.is_fold() {
 903                last.summary.input += summary;
 904                last.summary.output += summary;
 905                did_merge = true;
 906            }
 907        },
 908        &(),
 909    );
 910    if !did_merge {
 911        transforms.push(
 912            Transform {
 913                summary: TransformSummary {
 914                    input: summary,
 915                    output: summary,
 916                },
 917                placeholder: None,
 918            },
 919            &(),
 920        )
 921    }
 922}
 923
 924fn intersecting_folds<'a>(
 925    inlay_snapshot: &'a InlaySnapshot,
 926    folds: &'a SumTree<Fold>,
 927    range: Range<usize>,
 928    inclusive: bool,
 929) -> FilterCursor<'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, usize> {
 930    let buffer = &inlay_snapshot.buffer;
 931    let start = buffer.anchor_before(range.start.to_offset(buffer));
 932    let end = buffer.anchor_after(range.end.to_offset(buffer));
 933    let mut cursor = folds.filter::<_, usize>(buffer, move |summary| {
 934        let start_cmp = start.cmp(&summary.max_end, buffer);
 935        let end_cmp = end.cmp(&summary.min_start, buffer);
 936
 937        if inclusive {
 938            start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
 939        } else {
 940            start_cmp == Ordering::Less && end_cmp == Ordering::Greater
 941        }
 942    });
 943    cursor.next(buffer);
 944    cursor
 945}
 946
 947fn consolidate_inlay_edits(mut edits: Vec<InlayEdit>) -> Vec<InlayEdit> {
 948    edits.sort_unstable_by(|a, b| {
 949        a.old
 950            .start
 951            .cmp(&b.old.start)
 952            .then_with(|| b.old.end.cmp(&a.old.end))
 953    });
 954
 955    let _old_alloc_ptr = edits.as_ptr();
 956    let mut inlay_edits = edits.into_iter();
 957
 958    if let Some(mut first_edit) = inlay_edits.next() {
 959        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
 960        #[allow(clippy::filter_map_identity)]
 961        let mut v: Vec<_> = inlay_edits
 962            .scan(&mut first_edit, |prev_edit, edit| {
 963                if prev_edit.old.end >= edit.old.start {
 964                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
 965                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
 966                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
 967                    Some(None) // Skip this edit, it's merged
 968                } else {
 969                    let prev = std::mem::replace(*prev_edit, edit);
 970                    Some(Some(prev)) // Yield the previous edit
 971                }
 972            })
 973            .filter_map(|x| x)
 974            .collect();
 975        v.push(first_edit.clone());
 976        debug_assert_eq!(_old_alloc_ptr, v.as_ptr(), "Inlay edits were reallocated");
 977        v
 978    } else {
 979        vec![]
 980    }
 981}
 982
 983fn consolidate_fold_edits(mut edits: Vec<FoldEdit>) -> Vec<FoldEdit> {
 984    edits.sort_unstable_by(|a, b| {
 985        a.old
 986            .start
 987            .cmp(&b.old.start)
 988            .then_with(|| b.old.end.cmp(&a.old.end))
 989    });
 990    let _old_alloc_ptr = edits.as_ptr();
 991    let mut fold_edits = edits.into_iter();
 992
 993    if let Some(mut first_edit) = fold_edits.next() {
 994        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
 995        #[allow(clippy::filter_map_identity)]
 996        let mut v: Vec<_> = fold_edits
 997            .scan(&mut first_edit, |prev_edit, edit| {
 998                if prev_edit.old.end >= edit.old.start {
 999                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
1000                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
1001                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
1002                    Some(None) // Skip this edit, it's merged
1003                } else {
1004                    let prev = std::mem::replace(*prev_edit, edit);
1005                    Some(Some(prev)) // Yield the previous edit
1006                }
1007            })
1008            .filter_map(|x| x)
1009            .collect();
1010        v.push(first_edit.clone());
1011        v
1012    } else {
1013        vec![]
1014    }
1015}
1016
1017#[derive(Clone, Debug, Default)]
1018struct Transform {
1019    summary: TransformSummary,
1020    placeholder: Option<TransformPlaceholder>,
1021}
1022
1023#[derive(Clone, Debug)]
1024struct TransformPlaceholder {
1025    text: &'static str,
1026    renderer: ChunkRenderer,
1027}
1028
1029impl Transform {
1030    fn is_fold(&self) -> bool {
1031        self.placeholder.is_some()
1032    }
1033}
1034
1035#[derive(Clone, Debug, Default, Eq, PartialEq)]
1036struct TransformSummary {
1037    output: TextSummary,
1038    input: TextSummary,
1039}
1040
1041impl sum_tree::Item for Transform {
1042    type Summary = TransformSummary;
1043
1044    fn summary(&self, _cx: &()) -> Self::Summary {
1045        self.summary.clone()
1046    }
1047}
1048
1049impl sum_tree::Summary for TransformSummary {
1050    type Context = ();
1051
1052    fn zero(_cx: &()) -> Self {
1053        Default::default()
1054    }
1055
1056    fn add_summary(&mut self, other: &Self, _: &()) {
1057        self.input += &other.input;
1058        self.output += &other.output;
1059    }
1060}
1061
1062#[derive(Copy, Clone, Eq, PartialEq, Debug, Default, Ord, PartialOrd, Hash)]
1063pub struct FoldId(usize);
1064
1065impl From<FoldId> for ElementId {
1066    fn from(val: FoldId) -> Self {
1067        val.0.into()
1068    }
1069}
1070
1071#[derive(Clone, Debug, Eq, PartialEq)]
1072pub struct Fold {
1073    pub id: FoldId,
1074    pub range: FoldRange,
1075    pub placeholder: FoldPlaceholder,
1076}
1077
1078#[derive(Clone, Debug, Eq, PartialEq)]
1079pub struct FoldRange(Range<Anchor>);
1080
1081impl Deref for FoldRange {
1082    type Target = Range<Anchor>;
1083
1084    fn deref(&self) -> &Self::Target {
1085        &self.0
1086    }
1087}
1088
1089impl DerefMut for FoldRange {
1090    fn deref_mut(&mut self) -> &mut Self::Target {
1091        &mut self.0
1092    }
1093}
1094
1095impl Default for FoldRange {
1096    fn default() -> Self {
1097        Self(Anchor::min()..Anchor::max())
1098    }
1099}
1100
1101#[derive(Clone, Debug)]
1102struct FoldMetadata {
1103    range: FoldRange,
1104    width: Option<Pixels>,
1105}
1106
1107impl sum_tree::Item for Fold {
1108    type Summary = FoldSummary;
1109
1110    fn summary(&self, _cx: &MultiBufferSnapshot) -> Self::Summary {
1111        FoldSummary {
1112            start: self.range.start,
1113            end: self.range.end,
1114            min_start: self.range.start,
1115            max_end: self.range.end,
1116            count: 1,
1117        }
1118    }
1119}
1120
1121#[derive(Clone, Debug)]
1122pub struct FoldSummary {
1123    start: Anchor,
1124    end: Anchor,
1125    min_start: Anchor,
1126    max_end: Anchor,
1127    count: usize,
1128}
1129
1130impl Default for FoldSummary {
1131    fn default() -> Self {
1132        Self {
1133            start: Anchor::min(),
1134            end: Anchor::max(),
1135            min_start: Anchor::max(),
1136            max_end: Anchor::min(),
1137            count: 0,
1138        }
1139    }
1140}
1141
1142impl sum_tree::Summary for FoldSummary {
1143    type Context = MultiBufferSnapshot;
1144
1145    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1146        Default::default()
1147    }
1148
1149    fn add_summary(&mut self, other: &Self, buffer: &Self::Context) {
1150        if other.min_start.cmp(&self.min_start, buffer) == Ordering::Less {
1151            self.min_start = other.min_start;
1152        }
1153        if other.max_end.cmp(&self.max_end, buffer) == Ordering::Greater {
1154            self.max_end = other.max_end;
1155        }
1156
1157        #[cfg(debug_assertions)]
1158        {
1159            let start_comparison = self.start.cmp(&other.start, buffer);
1160            assert!(start_comparison <= Ordering::Equal);
1161            if start_comparison == Ordering::Equal {
1162                assert!(self.end.cmp(&other.end, buffer) >= Ordering::Equal);
1163            }
1164        }
1165
1166        self.start = other.start;
1167        self.end = other.end;
1168        self.count += other.count;
1169    }
1170}
1171
1172impl<'a> sum_tree::Dimension<'a, FoldSummary> for FoldRange {
1173    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1174        Default::default()
1175    }
1176
1177    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1178        self.0.start = summary.start;
1179        self.0.end = summary.end;
1180    }
1181}
1182
1183impl sum_tree::SeekTarget<'_, FoldSummary, FoldRange> for FoldRange {
1184    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
1185        AnchorRangeExt::cmp(&self.0, &other.0, buffer)
1186    }
1187}
1188
1189impl<'a> sum_tree::Dimension<'a, FoldSummary> for usize {
1190    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1191        Default::default()
1192    }
1193
1194    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1195        *self += summary.count;
1196    }
1197}
1198
1199#[derive(Clone)]
1200pub struct FoldRows<'a> {
1201    cursor: Cursor<'a, Transform, (FoldPoint, InlayPoint)>,
1202    input_rows: InlayBufferRows<'a>,
1203    fold_point: FoldPoint,
1204}
1205
1206impl FoldRows<'_> {
1207    pub(crate) fn seek(&mut self, row: u32) {
1208        let fold_point = FoldPoint::new(row, 0);
1209        self.cursor.seek(&fold_point, Bias::Left, &());
1210        let overshoot = fold_point.0 - self.cursor.start().0.0;
1211        let inlay_point = InlayPoint(self.cursor.start().1.0 + overshoot);
1212        self.input_rows.seek(inlay_point.row());
1213        self.fold_point = fold_point;
1214    }
1215}
1216
1217impl Iterator for FoldRows<'_> {
1218    type Item = RowInfo;
1219
1220    fn next(&mut self) -> Option<Self::Item> {
1221        let mut traversed_fold = false;
1222        while self.fold_point > self.cursor.end(&()).0 {
1223            self.cursor.next(&());
1224            traversed_fold = true;
1225            if self.cursor.item().is_none() {
1226                break;
1227            }
1228        }
1229
1230        if self.cursor.item().is_some() {
1231            if traversed_fold {
1232                self.input_rows.seek(self.cursor.start().1.0.row);
1233                self.input_rows.next();
1234            }
1235            *self.fold_point.row_mut() += 1;
1236            self.input_rows.next()
1237        } else {
1238            None
1239        }
1240    }
1241}
1242
1243/// A chunk of a buffer's text, along with its syntax highlight and
1244/// diagnostic status.
1245#[derive(Clone, Debug, Default)]
1246pub struct Chunk<'a> {
1247    /// The text of the chunk.
1248    pub text: &'a str,
1249    /// The syntax highlighting style of the chunk.
1250    pub syntax_highlight_id: Option<HighlightId>,
1251    /// The highlight style that has been applied to this chunk in
1252    /// the editor.
1253    pub highlight_style: Option<HighlightStyle>,
1254    /// The severity of diagnostic associated with this chunk, if any.
1255    pub diagnostic_severity: Option<lsp::DiagnosticSeverity>,
1256    /// Whether this chunk of text is marked as unnecessary.
1257    pub is_unnecessary: bool,
1258    /// Whether this chunk of text should be underlined.
1259    pub underline: bool,
1260    /// Whether this chunk of text was originally a tab character.
1261    pub is_tab: bool,
1262    /// An optional recipe for how the chunk should be presented.
1263    pub renderer: Option<ChunkRenderer>,
1264}
1265
1266/// A recipe for how the chunk should be presented.
1267#[derive(Clone)]
1268pub struct ChunkRenderer {
1269    /// The id of the fold associated with this chunk.
1270    pub id: FoldId,
1271    /// Creates a custom element to represent this chunk.
1272    pub render: Arc<dyn Send + Sync + Fn(&mut ChunkRendererContext) -> AnyElement>,
1273    /// If true, the element is constrained to the shaped width of the text.
1274    pub constrain_width: bool,
1275    /// The width of the element, as measured during the last layout pass.
1276    ///
1277    /// This is None if the element has not been laid out yet.
1278    pub measured_width: Option<Pixels>,
1279}
1280
1281pub struct ChunkRendererContext<'a, 'b> {
1282    pub window: &'a mut Window,
1283    pub context: &'b mut App,
1284    pub max_width: Pixels,
1285}
1286
1287impl fmt::Debug for ChunkRenderer {
1288    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1289        f.debug_struct("ChunkRenderer")
1290            .field("constrain_width", &self.constrain_width)
1291            .finish()
1292    }
1293}
1294
1295impl Deref for ChunkRendererContext<'_, '_> {
1296    type Target = App;
1297
1298    fn deref(&self) -> &Self::Target {
1299        self.context
1300    }
1301}
1302
1303impl DerefMut for ChunkRendererContext<'_, '_> {
1304    fn deref_mut(&mut self) -> &mut Self::Target {
1305        self.context
1306    }
1307}
1308
1309pub struct FoldChunks<'a> {
1310    transform_cursor: Cursor<'a, Transform, (FoldOffset, InlayOffset)>,
1311    inlay_chunks: InlayChunks<'a>,
1312    inlay_chunk: Option<(InlayOffset, language::Chunk<'a>)>,
1313    inlay_offset: InlayOffset,
1314    output_offset: FoldOffset,
1315    max_output_offset: FoldOffset,
1316}
1317
1318impl FoldChunks<'_> {
1319    pub(crate) fn seek(&mut self, range: Range<FoldOffset>) {
1320        self.transform_cursor.seek(&range.start, Bias::Right, &());
1321
1322        let inlay_start = {
1323            let overshoot = range.start.0 - self.transform_cursor.start().0.0;
1324            self.transform_cursor.start().1 + InlayOffset(overshoot)
1325        };
1326
1327        let transform_end = self.transform_cursor.end(&());
1328
1329        let inlay_end = if self
1330            .transform_cursor
1331            .item()
1332            .map_or(true, |transform| transform.is_fold())
1333        {
1334            inlay_start
1335        } else if range.end < transform_end.0 {
1336            let overshoot = range.end.0 - self.transform_cursor.start().0.0;
1337            self.transform_cursor.start().1 + InlayOffset(overshoot)
1338        } else {
1339            transform_end.1
1340        };
1341
1342        self.inlay_chunks.seek(inlay_start..inlay_end);
1343        self.inlay_chunk = None;
1344        self.inlay_offset = inlay_start;
1345        self.output_offset = range.start;
1346        self.max_output_offset = range.end;
1347    }
1348}
1349
1350impl<'a> Iterator for FoldChunks<'a> {
1351    type Item = Chunk<'a>;
1352
1353    fn next(&mut self) -> Option<Self::Item> {
1354        if self.output_offset >= self.max_output_offset {
1355            return None;
1356        }
1357
1358        let transform = self.transform_cursor.item()?;
1359
1360        // If we're in a fold, then return the fold's display text and
1361        // advance the transform and buffer cursors to the end of the fold.
1362        if let Some(placeholder) = transform.placeholder.as_ref() {
1363            self.inlay_chunk.take();
1364            self.inlay_offset += InlayOffset(transform.summary.input.len);
1365
1366            while self.inlay_offset >= self.transform_cursor.end(&()).1
1367                && self.transform_cursor.item().is_some()
1368            {
1369                self.transform_cursor.next(&());
1370            }
1371
1372            self.output_offset.0 += placeholder.text.len();
1373            return Some(Chunk {
1374                text: placeholder.text,
1375                renderer: Some(placeholder.renderer.clone()),
1376                ..Default::default()
1377            });
1378        }
1379
1380        // When we reach a non-fold region, seek the underlying text
1381        // chunk iterator to the next unfolded range.
1382        if self.inlay_offset == self.transform_cursor.start().1
1383            && self.inlay_chunks.offset() != self.inlay_offset
1384        {
1385            let transform_start = self.transform_cursor.start();
1386            let transform_end = self.transform_cursor.end(&());
1387            let inlay_end = if self.max_output_offset < transform_end.0 {
1388                let overshoot = self.max_output_offset.0 - transform_start.0.0;
1389                transform_start.1 + InlayOffset(overshoot)
1390            } else {
1391                transform_end.1
1392            };
1393
1394            self.inlay_chunks.seek(self.inlay_offset..inlay_end);
1395        }
1396
1397        // Retrieve a chunk from the current location in the buffer.
1398        if self.inlay_chunk.is_none() {
1399            let chunk_offset = self.inlay_chunks.offset();
1400            self.inlay_chunk = self.inlay_chunks.next().map(|chunk| (chunk_offset, chunk));
1401        }
1402
1403        // Otherwise, take a chunk from the buffer's text.
1404        if let Some((buffer_chunk_start, mut chunk)) = self.inlay_chunk.clone() {
1405            let buffer_chunk_end = buffer_chunk_start + InlayOffset(chunk.text.len());
1406            let transform_end = self.transform_cursor.end(&()).1;
1407            let chunk_end = buffer_chunk_end.min(transform_end);
1408
1409            chunk.text = &chunk.text
1410                [(self.inlay_offset - buffer_chunk_start).0..(chunk_end - buffer_chunk_start).0];
1411
1412            if chunk_end == transform_end {
1413                self.transform_cursor.next(&());
1414            } else if chunk_end == buffer_chunk_end {
1415                self.inlay_chunk.take();
1416            }
1417
1418            self.inlay_offset = chunk_end;
1419            self.output_offset.0 += chunk.text.len();
1420            return Some(Chunk {
1421                text: chunk.text,
1422                syntax_highlight_id: chunk.syntax_highlight_id,
1423                highlight_style: chunk.highlight_style,
1424                diagnostic_severity: chunk.diagnostic_severity,
1425                is_unnecessary: chunk.is_unnecessary,
1426                is_tab: chunk.is_tab,
1427                underline: chunk.underline,
1428                renderer: None,
1429            });
1430        }
1431
1432        None
1433    }
1434}
1435
1436#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1437pub struct FoldOffset(pub usize);
1438
1439impl FoldOffset {
1440    pub fn to_point(self, snapshot: &FoldSnapshot) -> FoldPoint {
1441        let mut cursor = snapshot
1442            .transforms
1443            .cursor::<(FoldOffset, TransformSummary)>(&());
1444        cursor.seek(&self, Bias::Right, &());
1445        let overshoot = if cursor.item().map_or(true, |t| t.is_fold()) {
1446            Point::new(0, (self.0 - cursor.start().0.0) as u32)
1447        } else {
1448            let inlay_offset = cursor.start().1.input.len + self.0 - cursor.start().0.0;
1449            let inlay_point = snapshot.inlay_snapshot.to_point(InlayOffset(inlay_offset));
1450            inlay_point.0 - cursor.start().1.input.lines
1451        };
1452        FoldPoint(cursor.start().1.output.lines + overshoot)
1453    }
1454
1455    #[cfg(test)]
1456    pub fn to_inlay_offset(self, snapshot: &FoldSnapshot) -> InlayOffset {
1457        let mut cursor = snapshot.transforms.cursor::<(FoldOffset, InlayOffset)>(&());
1458        cursor.seek(&self, Bias::Right, &());
1459        let overshoot = self.0 - cursor.start().0.0;
1460        InlayOffset(cursor.start().1.0 + overshoot)
1461    }
1462}
1463
1464impl Add for FoldOffset {
1465    type Output = Self;
1466
1467    fn add(self, rhs: Self) -> Self::Output {
1468        Self(self.0 + rhs.0)
1469    }
1470}
1471
1472impl AddAssign for FoldOffset {
1473    fn add_assign(&mut self, rhs: Self) {
1474        self.0 += rhs.0;
1475    }
1476}
1477
1478impl Sub for FoldOffset {
1479    type Output = Self;
1480
1481    fn sub(self, rhs: Self) -> Self::Output {
1482        Self(self.0 - rhs.0)
1483    }
1484}
1485
1486impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1487    fn zero(_cx: &()) -> Self {
1488        Default::default()
1489    }
1490
1491    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1492        self.0 += &summary.output.len;
1493    }
1494}
1495
1496impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayPoint {
1497    fn zero(_cx: &()) -> Self {
1498        Default::default()
1499    }
1500
1501    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1502        self.0 += &summary.input.lines;
1503    }
1504}
1505
1506impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayOffset {
1507    fn zero(_cx: &()) -> Self {
1508        Default::default()
1509    }
1510
1511    fn add_summary(&mut self, summary: &'a TransformSummary, _: &()) {
1512        self.0 += &summary.input.len;
1513    }
1514}
1515
1516pub type FoldEdit = Edit<FoldOffset>;
1517
1518#[cfg(test)]
1519mod tests {
1520    use super::*;
1521    use crate::{MultiBuffer, ToPoint, display_map::inlay_map::InlayMap};
1522    use Bias::{Left, Right};
1523    use collections::HashSet;
1524    use rand::prelude::*;
1525    use settings::SettingsStore;
1526    use std::{env, mem};
1527    use text::Patch;
1528    use util::RandomCharIter;
1529    use util::test::sample_text;
1530
1531    #[gpui::test]
1532    fn test_basic_folds(cx: &mut gpui::App) {
1533        init_test(cx);
1534        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1535        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1536        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1537        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1538        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1539
1540        let (mut writer, _, _) = map.write(inlay_snapshot, vec![]);
1541        let (snapshot2, edits) = writer.fold(vec![
1542            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1543            (Point::new(2, 4)..Point::new(4, 1), FoldPlaceholder::test()),
1544        ]);
1545        assert_eq!(snapshot2.text(), "aa⋯cc⋯eeeee");
1546        assert_eq!(
1547            edits,
1548            &[
1549                FoldEdit {
1550                    old: FoldOffset(2)..FoldOffset(16),
1551                    new: FoldOffset(2)..FoldOffset(5),
1552                },
1553                FoldEdit {
1554                    old: FoldOffset(18)..FoldOffset(29),
1555                    new: FoldOffset(7)..FoldOffset(10)
1556                },
1557            ]
1558        );
1559
1560        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1561            buffer.edit(
1562                vec![
1563                    (Point::new(0, 0)..Point::new(0, 1), "123"),
1564                    (Point::new(2, 3)..Point::new(2, 3), "123"),
1565                ],
1566                None,
1567                cx,
1568            );
1569            buffer.snapshot(cx)
1570        });
1571
1572        let (inlay_snapshot, inlay_edits) =
1573            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1574        let (snapshot3, edits) = map.read(inlay_snapshot, inlay_edits);
1575        assert_eq!(snapshot3.text(), "123a⋯c123c⋯eeeee");
1576        assert_eq!(
1577            edits,
1578            &[
1579                FoldEdit {
1580                    old: FoldOffset(0)..FoldOffset(1),
1581                    new: FoldOffset(0)..FoldOffset(3),
1582                },
1583                FoldEdit {
1584                    old: FoldOffset(6)..FoldOffset(6),
1585                    new: FoldOffset(8)..FoldOffset(11),
1586                },
1587            ]
1588        );
1589
1590        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1591            buffer.edit([(Point::new(2, 6)..Point::new(4, 3), "456")], None, cx);
1592            buffer.snapshot(cx)
1593        });
1594        let (inlay_snapshot, inlay_edits) =
1595            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1596        let (snapshot4, _) = map.read(inlay_snapshot.clone(), inlay_edits);
1597        assert_eq!(snapshot4.text(), "123a⋯c123456eee");
1598
1599        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1600        writer.unfold_intersecting(Some(Point::new(0, 4)..Point::new(0, 4)), false);
1601        let (snapshot5, _) = map.read(inlay_snapshot.clone(), vec![]);
1602        assert_eq!(snapshot5.text(), "123a⋯c123456eee");
1603
1604        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1605        writer.unfold_intersecting(Some(Point::new(0, 4)..Point::new(0, 4)), true);
1606        let (snapshot6, _) = map.read(inlay_snapshot, vec![]);
1607        assert_eq!(snapshot6.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1608    }
1609
1610    #[gpui::test]
1611    fn test_adjacent_folds(cx: &mut gpui::App) {
1612        init_test(cx);
1613        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1614        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1615        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1616        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1617
1618        {
1619            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1620
1621            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1622            writer.fold(vec![(5..8, FoldPlaceholder::test())]);
1623            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1624            assert_eq!(snapshot.text(), "abcde⋯ijkl");
1625
1626            // Create an fold adjacent to the start of the first fold.
1627            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1628            writer.fold(vec![
1629                (0..1, FoldPlaceholder::test()),
1630                (2..5, FoldPlaceholder::test()),
1631            ]);
1632            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1633            assert_eq!(snapshot.text(), "⋯b⋯ijkl");
1634
1635            // Create an fold adjacent to the end of the first fold.
1636            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1637            writer.fold(vec![
1638                (11..11, FoldPlaceholder::test()),
1639                (8..10, FoldPlaceholder::test()),
1640            ]);
1641            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1642            assert_eq!(snapshot.text(), "⋯b⋯kl");
1643        }
1644
1645        {
1646            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1647
1648            // Create two adjacent folds.
1649            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1650            writer.fold(vec![
1651                (0..2, FoldPlaceholder::test()),
1652                (2..5, FoldPlaceholder::test()),
1653            ]);
1654            let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1655            assert_eq!(snapshot.text(), "⋯fghijkl");
1656
1657            // Edit within one of the folds.
1658            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1659                buffer.edit([(0..1, "12345")], None, cx);
1660                buffer.snapshot(cx)
1661            });
1662            let (inlay_snapshot, inlay_edits) =
1663                inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1664            let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1665            assert_eq!(snapshot.text(), "12345⋯fghijkl");
1666        }
1667    }
1668
1669    #[gpui::test]
1670    fn test_overlapping_folds(cx: &mut gpui::App) {
1671        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1672        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1673        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1674        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1675        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1676        writer.fold(vec![
1677            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1678            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1679            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1680            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1681        ]);
1682        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1683        assert_eq!(snapshot.text(), "aa⋯eeeee");
1684    }
1685
1686    #[gpui::test]
1687    fn test_merging_folds_via_edit(cx: &mut gpui::App) {
1688        init_test(cx);
1689        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1690        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1691        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1692        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1693        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1694
1695        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1696        writer.fold(vec![
1697            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1698            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1699        ]);
1700        let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1701        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee");
1702
1703        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1704            buffer.edit([(Point::new(2, 2)..Point::new(3, 1), "")], None, cx);
1705            buffer.snapshot(cx)
1706        });
1707        let (inlay_snapshot, inlay_edits) =
1708            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1709        let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1710        assert_eq!(snapshot.text(), "aa⋯eeeee");
1711    }
1712
1713    #[gpui::test]
1714    fn test_folds_in_range(cx: &mut gpui::App) {
1715        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1716        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1717        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1718        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1719
1720        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1721        writer.fold(vec![
1722            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1723            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1724            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1725            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1726        ]);
1727        let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1728        let fold_ranges = snapshot
1729            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1730            .map(|fold| {
1731                fold.range.start.to_point(&buffer_snapshot)
1732                    ..fold.range.end.to_point(&buffer_snapshot)
1733            })
1734            .collect::<Vec<_>>();
1735        assert_eq!(
1736            fold_ranges,
1737            vec![
1738                Point::new(0, 2)..Point::new(2, 2),
1739                Point::new(1, 2)..Point::new(3, 2)
1740            ]
1741        );
1742    }
1743
1744    #[gpui::test(iterations = 100)]
1745    fn test_random_folds(cx: &mut gpui::App, mut rng: StdRng) {
1746        init_test(cx);
1747        let operations = env::var("OPERATIONS")
1748            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1749            .unwrap_or(10);
1750
1751        let len = rng.gen_range(0..10);
1752        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1753        let buffer = if rng.r#gen() {
1754            MultiBuffer::build_simple(&text, cx)
1755        } else {
1756            MultiBuffer::build_random(&mut rng, cx)
1757        };
1758        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1759        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1760        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1761
1762        let (mut initial_snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1763        let mut snapshot_edits = Vec::new();
1764
1765        let mut next_inlay_id = 0;
1766        for _ in 0..operations {
1767            log::info!("text: {:?}", buffer_snapshot.text());
1768            let mut buffer_edits = Vec::new();
1769            let mut inlay_edits = Vec::new();
1770            match rng.gen_range(0..=100) {
1771                0..=39 => {
1772                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1773                }
1774                40..=59 => {
1775                    let (_, edits) = inlay_map.randomly_mutate(&mut next_inlay_id, &mut rng);
1776                    inlay_edits = edits;
1777                }
1778                _ => buffer.update(cx, |buffer, cx| {
1779                    let subscription = buffer.subscribe();
1780                    let edit_count = rng.gen_range(1..=5);
1781                    buffer.randomly_mutate(&mut rng, edit_count, cx);
1782                    buffer_snapshot = buffer.snapshot(cx);
1783                    let edits = subscription.consume().into_inner();
1784                    log::info!("editing {:?}", edits);
1785                    buffer_edits.extend(edits);
1786                }),
1787            };
1788
1789            let (inlay_snapshot, new_inlay_edits) =
1790                inlay_map.sync(buffer_snapshot.clone(), buffer_edits);
1791            log::info!("inlay text {:?}", inlay_snapshot.text());
1792
1793            let inlay_edits = Patch::new(inlay_edits)
1794                .compose(new_inlay_edits)
1795                .into_inner();
1796            let (snapshot, edits) = map.read(inlay_snapshot.clone(), inlay_edits);
1797            snapshot_edits.push((snapshot.clone(), edits));
1798
1799            let mut expected_text: String = inlay_snapshot.text().to_string();
1800            for fold_range in map.merged_folds().into_iter().rev() {
1801                let fold_inlay_start = inlay_snapshot.to_inlay_offset(fold_range.start);
1802                let fold_inlay_end = inlay_snapshot.to_inlay_offset(fold_range.end);
1803                expected_text.replace_range(fold_inlay_start.0..fold_inlay_end.0, "⋯");
1804            }
1805
1806            assert_eq!(snapshot.text(), expected_text);
1807            log::info!(
1808                "fold text {:?} ({} lines)",
1809                expected_text,
1810                expected_text.matches('\n').count() + 1
1811            );
1812
1813            let mut prev_row = 0;
1814            let mut expected_buffer_rows = Vec::new();
1815            for fold_range in map.merged_folds() {
1816                let fold_start = inlay_snapshot
1817                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.start))
1818                    .row();
1819                let fold_end = inlay_snapshot
1820                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.end))
1821                    .row();
1822                expected_buffer_rows.extend(
1823                    inlay_snapshot
1824                        .row_infos(prev_row)
1825                        .take((1 + fold_start - prev_row) as usize),
1826                );
1827                prev_row = 1 + fold_end;
1828            }
1829            expected_buffer_rows.extend(inlay_snapshot.row_infos(prev_row));
1830
1831            assert_eq!(
1832                expected_buffer_rows.len(),
1833                expected_text.matches('\n').count() + 1,
1834                "wrong expected buffer rows {:?}. text: {:?}",
1835                expected_buffer_rows,
1836                expected_text
1837            );
1838
1839            for (output_row, line) in expected_text.lines().enumerate() {
1840                let line_len = snapshot.line_len(output_row as u32);
1841                assert_eq!(line_len, line.len() as u32);
1842            }
1843
1844            let longest_row = snapshot.longest_row();
1845            let longest_char_column = expected_text
1846                .split('\n')
1847                .nth(longest_row as usize)
1848                .unwrap()
1849                .chars()
1850                .count();
1851            let mut fold_point = FoldPoint::new(0, 0);
1852            let mut fold_offset = FoldOffset(0);
1853            let mut char_column = 0;
1854            for c in expected_text.chars() {
1855                let inlay_point = fold_point.to_inlay_point(&snapshot);
1856                let inlay_offset = fold_offset.to_inlay_offset(&snapshot);
1857                assert_eq!(
1858                    snapshot.to_fold_point(inlay_point, Right),
1859                    fold_point,
1860                    "{:?} -> fold point",
1861                    inlay_point,
1862                );
1863                assert_eq!(
1864                    inlay_snapshot.to_offset(inlay_point),
1865                    inlay_offset,
1866                    "inlay_snapshot.to_offset({:?})",
1867                    inlay_point,
1868                );
1869                assert_eq!(
1870                    fold_point.to_offset(&snapshot),
1871                    fold_offset,
1872                    "fold_point.to_offset({:?})",
1873                    fold_point,
1874                );
1875
1876                if c == '\n' {
1877                    *fold_point.row_mut() += 1;
1878                    *fold_point.column_mut() = 0;
1879                    char_column = 0;
1880                } else {
1881                    *fold_point.column_mut() += c.len_utf8() as u32;
1882                    char_column += 1;
1883                }
1884                fold_offset.0 += c.len_utf8();
1885                if char_column > longest_char_column {
1886                    panic!(
1887                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
1888                        longest_row,
1889                        longest_char_column,
1890                        fold_point.row(),
1891                        char_column
1892                    );
1893                }
1894            }
1895
1896            for _ in 0..5 {
1897                let mut start = snapshot
1898                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Left);
1899                let mut end = snapshot
1900                    .clip_offset(FoldOffset(rng.gen_range(0..=snapshot.len().0)), Bias::Right);
1901                if start > end {
1902                    mem::swap(&mut start, &mut end);
1903                }
1904
1905                let text = &expected_text[start.0..end.0];
1906                assert_eq!(
1907                    snapshot
1908                        .chunks(start..end, false, Highlights::default())
1909                        .map(|c| c.text)
1910                        .collect::<String>(),
1911                    text,
1912                );
1913            }
1914
1915            let mut fold_row = 0;
1916            while fold_row < expected_buffer_rows.len() as u32 {
1917                assert_eq!(
1918                    snapshot.row_infos(fold_row).collect::<Vec<_>>(),
1919                    expected_buffer_rows[(fold_row as usize)..],
1920                    "wrong buffer rows starting at fold row {}",
1921                    fold_row,
1922                );
1923                fold_row += 1;
1924            }
1925
1926            let folded_buffer_rows = map
1927                .merged_folds()
1928                .iter()
1929                .flat_map(|fold_range| {
1930                    let start_row = fold_range.start.to_point(&buffer_snapshot).row;
1931                    let end = fold_range.end.to_point(&buffer_snapshot);
1932                    if end.column == 0 {
1933                        start_row..end.row
1934                    } else {
1935                        start_row..end.row + 1
1936                    }
1937                })
1938                .collect::<HashSet<_>>();
1939            for row in 0..=buffer_snapshot.max_point().row {
1940                assert_eq!(
1941                    snapshot.is_line_folded(MultiBufferRow(row)),
1942                    folded_buffer_rows.contains(&row),
1943                    "expected buffer row {}{} to be folded",
1944                    row,
1945                    if folded_buffer_rows.contains(&row) {
1946                        ""
1947                    } else {
1948                        " not"
1949                    }
1950                );
1951            }
1952
1953            for _ in 0..5 {
1954                let end =
1955                    buffer_snapshot.clip_offset(rng.gen_range(0..=buffer_snapshot.len()), Right);
1956                let start = buffer_snapshot.clip_offset(rng.gen_range(0..=end), Left);
1957                let expected_folds = map
1958                    .snapshot
1959                    .folds
1960                    .items(&buffer_snapshot)
1961                    .into_iter()
1962                    .filter(|fold| {
1963                        let start = buffer_snapshot.anchor_before(start);
1964                        let end = buffer_snapshot.anchor_after(end);
1965                        start.cmp(&fold.range.end, &buffer_snapshot) == Ordering::Less
1966                            && end.cmp(&fold.range.start, &buffer_snapshot) == Ordering::Greater
1967                    })
1968                    .collect::<Vec<_>>();
1969
1970                assert_eq!(
1971                    snapshot
1972                        .folds_in_range(start..end)
1973                        .cloned()
1974                        .collect::<Vec<_>>(),
1975                    expected_folds
1976                );
1977            }
1978
1979            let text = snapshot.text();
1980            for _ in 0..5 {
1981                let start_row = rng.gen_range(0..=snapshot.max_point().row());
1982                let start_column = rng.gen_range(0..=snapshot.line_len(start_row));
1983                let end_row = rng.gen_range(0..=snapshot.max_point().row());
1984                let end_column = rng.gen_range(0..=snapshot.line_len(end_row));
1985                let mut start =
1986                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
1987                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
1988                if start > end {
1989                    mem::swap(&mut start, &mut end);
1990                }
1991
1992                let lines = start..end;
1993                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
1994                assert_eq!(
1995                    snapshot.text_summary_for_range(lines),
1996                    TextSummary::from(&text[bytes.start.0..bytes.end.0])
1997                )
1998            }
1999
2000            let mut text = initial_snapshot.text();
2001            for (snapshot, edits) in snapshot_edits.drain(..) {
2002                let new_text = snapshot.text();
2003                for edit in edits {
2004                    let old_bytes = edit.new.start.0..edit.new.start.0 + edit.old_len().0;
2005                    let new_bytes = edit.new.start.0..edit.new.end.0;
2006                    text.replace_range(old_bytes, &new_text[new_bytes]);
2007                }
2008
2009                assert_eq!(text, new_text);
2010                initial_snapshot = snapshot;
2011            }
2012        }
2013    }
2014
2015    #[gpui::test]
2016    fn test_buffer_rows(cx: &mut gpui::App) {
2017        let text = sample_text(6, 6, 'a') + "\n";
2018        let buffer = MultiBuffer::build_simple(&text, cx);
2019
2020        let buffer_snapshot = buffer.read(cx).snapshot(cx);
2021        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
2022        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
2023
2024        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
2025        writer.fold(vec![
2026            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
2027            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
2028        ]);
2029
2030        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
2031        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee\nffffff\n");
2032        assert_eq!(
2033            snapshot
2034                .row_infos(0)
2035                .map(|info| info.buffer_row)
2036                .collect::<Vec<_>>(),
2037            [Some(0), Some(3), Some(5), Some(6)]
2038        );
2039        assert_eq!(
2040            snapshot
2041                .row_infos(3)
2042                .map(|info| info.buffer_row)
2043                .collect::<Vec<_>>(),
2044            [Some(6)]
2045        );
2046    }
2047
2048    fn init_test(cx: &mut gpui::App) {
2049        let store = SettingsStore::test(cx);
2050        cx.set_global(store);
2051    }
2052
2053    impl FoldMap {
2054        fn merged_folds(&self) -> Vec<Range<usize>> {
2055            let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2056            let buffer = &inlay_snapshot.buffer;
2057            let mut folds = self.snapshot.folds.items(buffer);
2058            // Ensure sorting doesn't change how folds get merged and displayed.
2059            folds.sort_by(|a, b| a.range.cmp(&b.range, buffer));
2060            let mut folds = folds
2061                .iter()
2062                .map(|fold| fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer))
2063                .peekable();
2064
2065            let mut merged_folds = Vec::new();
2066            while let Some(mut fold_range) = folds.next() {
2067                while let Some(next_range) = folds.peek() {
2068                    if fold_range.end >= next_range.start {
2069                        if next_range.end > fold_range.end {
2070                            fold_range.end = next_range.end;
2071                        }
2072                        folds.next();
2073                    } else {
2074                        break;
2075                    }
2076                }
2077                if fold_range.end > fold_range.start {
2078                    merged_folds.push(fold_range);
2079                }
2080            }
2081            merged_folds
2082        }
2083
2084        pub fn randomly_mutate(
2085            &mut self,
2086            rng: &mut impl Rng,
2087        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
2088            let mut snapshot_edits = Vec::new();
2089            match rng.gen_range(0..=100) {
2090                0..=39 if !self.snapshot.folds.is_empty() => {
2091                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2092                    let buffer = &inlay_snapshot.buffer;
2093                    let mut to_unfold = Vec::new();
2094                    for _ in 0..rng.gen_range(1..=3) {
2095                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
2096                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
2097                        to_unfold.push(start..end);
2098                    }
2099                    let inclusive = rng.r#gen();
2100                    log::info!("unfolding {:?} (inclusive: {})", to_unfold, inclusive);
2101                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
2102                    snapshot_edits.push((snapshot, edits));
2103                    let (snapshot, edits) = writer.unfold_intersecting(to_unfold, inclusive);
2104                    snapshot_edits.push((snapshot, edits));
2105                }
2106                _ => {
2107                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2108                    let buffer = &inlay_snapshot.buffer;
2109                    let mut to_fold = Vec::new();
2110                    for _ in 0..rng.gen_range(1..=2) {
2111                        let end = buffer.clip_offset(rng.gen_range(0..=buffer.len()), Right);
2112                        let start = buffer.clip_offset(rng.gen_range(0..=end), Left);
2113                        to_fold.push((start..end, FoldPlaceholder::test()));
2114                    }
2115                    log::info!("folding {:?}", to_fold);
2116                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
2117                    snapshot_edits.push((snapshot, edits));
2118                    let (snapshot, edits) = writer.fold(to_fold);
2119                    snapshot_edits.push((snapshot, edits));
2120                }
2121            }
2122            snapshot_edits
2123        }
2124    }
2125}