fold_map.rs

   1use crate::display_map::inlay_map::InlayChunk;
   2
   3use super::{
   4    Highlights,
   5    inlay_map::{InlayBufferRows, InlayChunks, InlayEdit, InlayOffset, InlayPoint, InlaySnapshot},
   6};
   7use gpui::{AnyElement, App, ElementId, HighlightStyle, Pixels, Window};
   8use language::{Edit, HighlightId, Point};
   9use multi_buffer::{
  10    Anchor, AnchorRangeExt, MBTextSummary, MultiBufferOffset, MultiBufferRow, MultiBufferSnapshot,
  11    RowInfo, ToOffset,
  12};
  13use project::InlayId;
  14use std::{
  15    any::TypeId,
  16    cmp::{self, Ordering},
  17    fmt, iter,
  18    ops::{Add, AddAssign, Deref, DerefMut, Range, Sub, SubAssign},
  19    sync::Arc,
  20    usize,
  21};
  22use sum_tree::{Bias, Cursor, Dimensions, FilterCursor, SumTree, Summary, TreeMap};
  23use ui::IntoElement as _;
  24use util::post_inc;
  25
  26#[derive(Clone)]
  27pub struct FoldPlaceholder {
  28    /// Creates an element to represent this fold's placeholder.
  29    pub render: Arc<dyn Send + Sync + Fn(FoldId, Range<Anchor>, &mut App) -> AnyElement>,
  30    /// If true, the element is constrained to the shaped width of an ellipsis.
  31    pub constrain_width: bool,
  32    /// If true, merges the fold with an adjacent one.
  33    pub merge_adjacent: bool,
  34    /// Category of the fold. Useful for carefully removing from overlapping folds.
  35    pub type_tag: Option<TypeId>,
  36}
  37
  38impl Default for FoldPlaceholder {
  39    fn default() -> Self {
  40        Self {
  41            render: Arc::new(|_, _, _| gpui::Empty.into_any_element()),
  42            constrain_width: true,
  43            merge_adjacent: true,
  44            type_tag: None,
  45        }
  46    }
  47}
  48
  49impl FoldPlaceholder {
  50    #[cfg(any(test, feature = "test-support"))]
  51    pub fn test() -> Self {
  52        Self {
  53            render: Arc::new(|_id, _range, _cx| gpui::Empty.into_any_element()),
  54            constrain_width: true,
  55            merge_adjacent: true,
  56            type_tag: None,
  57        }
  58    }
  59}
  60
  61impl fmt::Debug for FoldPlaceholder {
  62    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  63        f.debug_struct("FoldPlaceholder")
  64            .field("constrain_width", &self.constrain_width)
  65            .finish()
  66    }
  67}
  68
  69impl Eq for FoldPlaceholder {}
  70
  71impl PartialEq for FoldPlaceholder {
  72    fn eq(&self, other: &Self) -> bool {
  73        Arc::ptr_eq(&self.render, &other.render) && self.constrain_width == other.constrain_width
  74    }
  75}
  76
  77#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
  78pub struct FoldPoint(pub Point);
  79
  80impl FoldPoint {
  81    pub fn new(row: u32, column: u32) -> Self {
  82        Self(Point::new(row, column))
  83    }
  84
  85    pub fn row(self) -> u32 {
  86        self.0.row
  87    }
  88
  89    pub fn column(self) -> u32 {
  90        self.0.column
  91    }
  92
  93    pub fn row_mut(&mut self) -> &mut u32 {
  94        &mut self.0.row
  95    }
  96
  97    #[cfg(test)]
  98    pub fn column_mut(&mut self) -> &mut u32 {
  99        &mut self.0.column
 100    }
 101
 102    #[ztracing::instrument(skip_all)]
 103    pub fn to_inlay_point(self, snapshot: &FoldSnapshot) -> InlayPoint {
 104        let (start, _, _) = snapshot
 105            .transforms
 106            .find::<Dimensions<FoldPoint, InlayPoint>, _>((), &self, Bias::Right);
 107        let overshoot = self.0 - start.0.0;
 108        InlayPoint(start.1.0 + overshoot)
 109    }
 110
 111    #[ztracing::instrument(skip_all)]
 112    pub fn to_offset(self, snapshot: &FoldSnapshot) -> FoldOffset {
 113        let (start, _, item) = snapshot
 114            .transforms
 115            .find::<Dimensions<FoldPoint, TransformSummary>, _>((), &self, Bias::Right);
 116        let overshoot = self.0 - start.1.output.lines;
 117        let mut offset = start.1.output.len;
 118        if !overshoot.is_zero() {
 119            let transform = item.expect("display point out of range");
 120            assert!(transform.placeholder.is_none());
 121            let end_inlay_offset = snapshot
 122                .inlay_snapshot
 123                .to_offset(InlayPoint(start.1.input.lines + overshoot));
 124            offset += end_inlay_offset.0 - start.1.input.len;
 125        }
 126        FoldOffset(offset)
 127    }
 128}
 129
 130impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldPoint {
 131    fn zero(_cx: ()) -> Self {
 132        Default::default()
 133    }
 134
 135    fn add_summary(&mut self, summary: &'a TransformSummary, _: ()) {
 136        self.0 += &summary.output.lines;
 137    }
 138}
 139
 140pub(crate) struct FoldMapWriter<'a>(&'a mut FoldMap);
 141
 142impl FoldMapWriter<'_> {
 143    #[ztracing::instrument(skip_all)]
 144    pub(crate) fn fold<T: ToOffset>(
 145        &mut self,
 146        ranges: impl IntoIterator<Item = (Range<T>, FoldPlaceholder)>,
 147    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 148        let mut edits = Vec::new();
 149        let mut folds = Vec::new();
 150        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 151        for (range, fold_text) in ranges.into_iter() {
 152            let buffer = &snapshot.buffer;
 153            let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 154
 155            // Ignore any empty ranges.
 156            if range.start == range.end {
 157                continue;
 158            }
 159
 160            // For now, ignore any ranges that span an excerpt boundary.
 161            let fold_range =
 162                FoldRange(buffer.anchor_after(range.start)..buffer.anchor_before(range.end));
 163            if fold_range.0.start.excerpt_id != fold_range.0.end.excerpt_id {
 164                continue;
 165            }
 166
 167            folds.push(Fold {
 168                id: FoldId(post_inc(&mut self.0.next_fold_id.0)),
 169                range: fold_range,
 170                placeholder: fold_text,
 171            });
 172
 173            let inlay_range =
 174                snapshot.to_inlay_offset(range.start)..snapshot.to_inlay_offset(range.end);
 175            edits.push(InlayEdit {
 176                old: inlay_range.clone(),
 177                new: inlay_range,
 178            });
 179        }
 180
 181        let buffer = &snapshot.buffer;
 182        folds.sort_unstable_by(|a, b| sum_tree::SeekTarget::cmp(&a.range, &b.range, buffer));
 183
 184        self.0.snapshot.folds = {
 185            let mut new_tree = SumTree::new(buffer);
 186            let mut cursor = self.0.snapshot.folds.cursor::<FoldRange>(buffer);
 187            for fold in folds {
 188                self.0.snapshot.fold_metadata_by_id.insert(
 189                    fold.id,
 190                    FoldMetadata {
 191                        range: fold.range.clone(),
 192                        width: None,
 193                    },
 194                );
 195                new_tree.append(cursor.slice(&fold.range, Bias::Right), buffer);
 196                new_tree.push(fold, buffer);
 197            }
 198            new_tree.append(cursor.suffix(), buffer);
 199            new_tree
 200        };
 201
 202        let edits = consolidate_inlay_edits(edits);
 203        let edits = self.0.sync(snapshot.clone(), edits);
 204        (self.0.snapshot.clone(), edits)
 205    }
 206
 207    /// Removes any folds with the given ranges.
 208    #[ztracing::instrument(skip_all)]
 209    pub(crate) fn remove_folds<T: ToOffset>(
 210        &mut self,
 211        ranges: impl IntoIterator<Item = Range<T>>,
 212        type_id: TypeId,
 213    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 214        self.remove_folds_with(
 215            ranges,
 216            |fold| fold.placeholder.type_tag == Some(type_id),
 217            false,
 218        )
 219    }
 220
 221    /// Removes any folds whose ranges intersect the given ranges.
 222    #[ztracing::instrument(skip_all)]
 223    pub(crate) fn unfold_intersecting<T: ToOffset>(
 224        &mut self,
 225        ranges: impl IntoIterator<Item = Range<T>>,
 226        inclusive: bool,
 227    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 228        self.remove_folds_with(ranges, |_| true, inclusive)
 229    }
 230
 231    /// Removes any folds that intersect the given ranges and for which the given predicate
 232    /// returns true.
 233    #[ztracing::instrument(skip_all)]
 234    fn remove_folds_with<T: ToOffset>(
 235        &mut self,
 236        ranges: impl IntoIterator<Item = Range<T>>,
 237        should_unfold: impl Fn(&Fold) -> bool,
 238        inclusive: bool,
 239    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 240        let mut edits = Vec::new();
 241        let mut fold_ixs_to_delete = Vec::new();
 242        let snapshot = self.0.snapshot.inlay_snapshot.clone();
 243        let buffer = &snapshot.buffer;
 244        for range in ranges.into_iter() {
 245            let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 246            let mut folds_cursor =
 247                intersecting_folds(&snapshot, &self.0.snapshot.folds, range.clone(), inclusive);
 248            while let Some(fold) = folds_cursor.item() {
 249                let offset_range =
 250                    fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer);
 251                if should_unfold(fold) {
 252                    if offset_range.end > offset_range.start {
 253                        let inlay_range = snapshot.to_inlay_offset(offset_range.start)
 254                            ..snapshot.to_inlay_offset(offset_range.end);
 255                        edits.push(InlayEdit {
 256                            old: inlay_range.clone(),
 257                            new: inlay_range,
 258                        });
 259                    }
 260                    fold_ixs_to_delete.push(*folds_cursor.start());
 261                    self.0.snapshot.fold_metadata_by_id.remove(&fold.id);
 262                }
 263                folds_cursor.next();
 264            }
 265        }
 266
 267        fold_ixs_to_delete.sort_unstable();
 268        fold_ixs_to_delete.dedup();
 269
 270        self.0.snapshot.folds = {
 271            let mut cursor = self.0.snapshot.folds.cursor::<MultiBufferOffset>(buffer);
 272            let mut folds = SumTree::new(buffer);
 273            for fold_ix in fold_ixs_to_delete {
 274                folds.append(cursor.slice(&fold_ix, Bias::Right), buffer);
 275                cursor.next();
 276            }
 277            folds.append(cursor.suffix(), buffer);
 278            folds
 279        };
 280
 281        let edits = consolidate_inlay_edits(edits);
 282        let edits = self.0.sync(snapshot.clone(), edits);
 283        (self.0.snapshot.clone(), edits)
 284    }
 285
 286    #[ztracing::instrument(skip_all)]
 287    pub(crate) fn update_fold_widths(
 288        &mut self,
 289        new_widths: impl IntoIterator<Item = (ChunkRendererId, Pixels)>,
 290    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 291        let mut edits = Vec::new();
 292        let inlay_snapshot = self.0.snapshot.inlay_snapshot.clone();
 293        let buffer = &inlay_snapshot.buffer;
 294
 295        for (id, new_width) in new_widths {
 296            let ChunkRendererId::Fold(id) = id else {
 297                continue;
 298            };
 299            if let Some(metadata) = self.0.snapshot.fold_metadata_by_id.get(&id).cloned()
 300                && Some(new_width) != metadata.width
 301            {
 302                let buffer_start = metadata.range.start.to_offset(buffer);
 303                let buffer_end = metadata.range.end.to_offset(buffer);
 304                let inlay_range = inlay_snapshot.to_inlay_offset(buffer_start)
 305                    ..inlay_snapshot.to_inlay_offset(buffer_end);
 306                edits.push(InlayEdit {
 307                    old: inlay_range.clone(),
 308                    new: inlay_range.clone(),
 309                });
 310
 311                self.0.snapshot.fold_metadata_by_id.insert(
 312                    id,
 313                    FoldMetadata {
 314                        range: metadata.range,
 315                        width: Some(new_width),
 316                    },
 317                );
 318            }
 319        }
 320
 321        let edits = consolidate_inlay_edits(edits);
 322        let edits = self.0.sync(inlay_snapshot, edits);
 323        (self.0.snapshot.clone(), edits)
 324    }
 325}
 326
 327/// Decides where the fold indicators should be; also tracks parts of a source file that are currently folded.
 328///
 329/// See the [`display_map` module documentation](crate::display_map) for more information.
 330pub struct FoldMap {
 331    snapshot: FoldSnapshot,
 332    next_fold_id: FoldId,
 333}
 334
 335impl FoldMap {
 336    #[ztracing::instrument(skip_all)]
 337    pub fn new(inlay_snapshot: InlaySnapshot) -> (Self, FoldSnapshot) {
 338        let this = Self {
 339            snapshot: FoldSnapshot {
 340                folds: SumTree::new(&inlay_snapshot.buffer),
 341                transforms: SumTree::from_item(
 342                    Transform {
 343                        summary: TransformSummary {
 344                            input: inlay_snapshot.text_summary(),
 345                            output: inlay_snapshot.text_summary(),
 346                        },
 347                        placeholder: None,
 348                    },
 349                    (),
 350                ),
 351                inlay_snapshot: inlay_snapshot,
 352                version: 0,
 353                fold_metadata_by_id: TreeMap::default(),
 354            },
 355            next_fold_id: FoldId::default(),
 356        };
 357        let snapshot = this.snapshot.clone();
 358        (this, snapshot)
 359    }
 360
 361    #[ztracing::instrument(skip_all)]
 362    pub fn read(
 363        &mut self,
 364        inlay_snapshot: InlaySnapshot,
 365        edits: Vec<InlayEdit>,
 366    ) -> (FoldSnapshot, Vec<FoldEdit>) {
 367        let edits = self.sync(inlay_snapshot, edits);
 368        self.check_invariants();
 369        (self.snapshot.clone(), edits)
 370    }
 371
 372    #[ztracing::instrument(skip_all)]
 373    pub(crate) fn write(
 374        &mut self,
 375        inlay_snapshot: InlaySnapshot,
 376        edits: Vec<InlayEdit>,
 377    ) -> (FoldMapWriter<'_>, FoldSnapshot, Vec<FoldEdit>) {
 378        let (snapshot, edits) = self.read(inlay_snapshot, edits);
 379        (FoldMapWriter(self), snapshot, edits)
 380    }
 381
 382    #[ztracing::instrument(skip_all)]
 383    fn check_invariants(&self) {
 384        if cfg!(test) {
 385            assert_eq!(
 386                self.snapshot.transforms.summary().input.len,
 387                self.snapshot.inlay_snapshot.len().0,
 388                "transform tree does not match inlay snapshot's length"
 389            );
 390
 391            let mut prev_transform_isomorphic = false;
 392            for transform in self.snapshot.transforms.iter() {
 393                if !transform.is_fold() && prev_transform_isomorphic {
 394                    panic!(
 395                        "found adjacent isomorphic transforms: {:?}",
 396                        self.snapshot.transforms.items(())
 397                    );
 398                }
 399                prev_transform_isomorphic = !transform.is_fold();
 400            }
 401
 402            let mut folds = self.snapshot.folds.iter().peekable();
 403            while let Some(fold) = folds.next() {
 404                if let Some(next_fold) = folds.peek() {
 405                    let comparison = fold.range.cmp(&next_fold.range, self.snapshot.buffer());
 406                    assert!(comparison.is_le());
 407                }
 408            }
 409        }
 410    }
 411
 412    #[ztracing::instrument(skip_all)]
 413    fn sync(
 414        &mut self,
 415        inlay_snapshot: InlaySnapshot,
 416        inlay_edits: Vec<InlayEdit>,
 417    ) -> Vec<FoldEdit> {
 418        if inlay_edits.is_empty() {
 419            if self.snapshot.inlay_snapshot.version != inlay_snapshot.version {
 420                self.snapshot.version += 1;
 421            }
 422            self.snapshot.inlay_snapshot = inlay_snapshot;
 423            Vec::new()
 424        } else {
 425            let mut inlay_edits_iter = inlay_edits.iter().cloned().peekable();
 426
 427            let mut new_transforms = SumTree::<Transform>::default();
 428            let mut cursor = self.snapshot.transforms.cursor::<InlayOffset>(());
 429            cursor.seek(&InlayOffset(MultiBufferOffset(0)), Bias::Right);
 430
 431            while let Some(mut edit) = inlay_edits_iter.next() {
 432                if let Some(item) = cursor.item()
 433                    && !item.is_fold()
 434                {
 435                    new_transforms.update_last(
 436                        |transform| {
 437                            if !transform.is_fold() {
 438                                transform.summary.add_summary(&item.summary, ());
 439                                cursor.next();
 440                            }
 441                        },
 442                        (),
 443                    );
 444                }
 445                new_transforms.append(cursor.slice(&edit.old.start, Bias::Left), ());
 446                edit.new.start -= edit.old.start - *cursor.start();
 447                edit.old.start = *cursor.start();
 448
 449                cursor.seek(&edit.old.end, Bias::Right);
 450                cursor.next();
 451
 452                let mut delta = edit.new_len() as isize - edit.old_len() as isize;
 453                loop {
 454                    edit.old.end = *cursor.start();
 455
 456                    if let Some(next_edit) = inlay_edits_iter.peek() {
 457                        if next_edit.old.start > edit.old.end {
 458                            break;
 459                        }
 460
 461                        let next_edit = inlay_edits_iter.next().unwrap();
 462                        delta += next_edit.new_len() as isize - next_edit.old_len() as isize;
 463
 464                        if next_edit.old.end >= edit.old.end {
 465                            edit.old.end = next_edit.old.end;
 466                            cursor.seek(&edit.old.end, Bias::Right);
 467                            cursor.next();
 468                        }
 469                    } else {
 470                        break;
 471                    }
 472                }
 473
 474                edit.new.end = InlayOffset(MultiBufferOffset(
 475                    ((edit.new.start + edit.old_len()).0.0 as isize + delta) as usize,
 476                ));
 477
 478                let anchor = inlay_snapshot
 479                    .buffer
 480                    .anchor_before(inlay_snapshot.to_buffer_offset(edit.new.start));
 481                let mut folds_cursor = self
 482                    .snapshot
 483                    .folds
 484                    .cursor::<FoldRange>(&inlay_snapshot.buffer);
 485                folds_cursor.seek(&FoldRange(anchor..Anchor::max()), Bias::Left);
 486
 487                let mut folds = iter::from_fn({
 488                    let inlay_snapshot = &inlay_snapshot;
 489                    move || {
 490                        let item = folds_cursor.item().map(|fold| {
 491                            let buffer_start = fold.range.start.to_offset(&inlay_snapshot.buffer);
 492                            let buffer_end = fold.range.end.to_offset(&inlay_snapshot.buffer);
 493                            (
 494                                fold.clone(),
 495                                inlay_snapshot.to_inlay_offset(buffer_start)
 496                                    ..inlay_snapshot.to_inlay_offset(buffer_end),
 497                            )
 498                        });
 499                        folds_cursor.next();
 500                        item
 501                    }
 502                })
 503                .peekable();
 504
 505                while folds
 506                    .peek()
 507                    .is_some_and(|(_, fold_range)| fold_range.start < edit.new.end)
 508                {
 509                    let (fold, mut fold_range) = folds.next().unwrap();
 510                    let sum = new_transforms.summary();
 511
 512                    assert!(fold_range.start.0 >= sum.input.len);
 513
 514                    while folds.peek().is_some_and(|(next_fold, next_fold_range)| {
 515                        next_fold_range.start < fold_range.end
 516                            || (next_fold_range.start == fold_range.end
 517                                && fold.placeholder.merge_adjacent
 518                                && next_fold.placeholder.merge_adjacent)
 519                    }) {
 520                        let (_, next_fold_range) = folds.next().unwrap();
 521                        if next_fold_range.end > fold_range.end {
 522                            fold_range.end = next_fold_range.end;
 523                        }
 524                    }
 525
 526                    if fold_range.start.0 > sum.input.len {
 527                        let text_summary = inlay_snapshot
 528                            .text_summary_for_range(InlayOffset(sum.input.len)..fold_range.start);
 529                        push_isomorphic(&mut new_transforms, text_summary);
 530                    }
 531
 532                    if fold_range.end > fold_range.start {
 533                        const ELLIPSIS: &str = "";
 534
 535                        let fold_id = fold.id;
 536                        new_transforms.push(
 537                            Transform {
 538                                summary: TransformSummary {
 539                                    output: MBTextSummary::from(ELLIPSIS),
 540                                    input: inlay_snapshot
 541                                        .text_summary_for_range(fold_range.start..fold_range.end),
 542                                },
 543                                placeholder: Some(TransformPlaceholder {
 544                                    text: ELLIPSIS,
 545                                    chars: 1,
 546                                    renderer: ChunkRenderer {
 547                                        id: ChunkRendererId::Fold(fold.id),
 548                                        render: Arc::new(move |cx| {
 549                                            (fold.placeholder.render)(
 550                                                fold_id,
 551                                                fold.range.0.clone(),
 552                                                cx.context,
 553                                            )
 554                                        }),
 555                                        constrain_width: fold.placeholder.constrain_width,
 556                                        measured_width: self.snapshot.fold_width(&fold_id),
 557                                    },
 558                                }),
 559                            },
 560                            (),
 561                        );
 562                    }
 563                }
 564
 565                let sum = new_transforms.summary();
 566                if sum.input.len < edit.new.end.0 {
 567                    let text_summary = inlay_snapshot
 568                        .text_summary_for_range(InlayOffset(sum.input.len)..edit.new.end);
 569                    push_isomorphic(&mut new_transforms, text_summary);
 570                }
 571            }
 572
 573            new_transforms.append(cursor.suffix(), ());
 574            if new_transforms.is_empty() {
 575                let text_summary = inlay_snapshot.text_summary();
 576                push_isomorphic(&mut new_transforms, text_summary);
 577            }
 578
 579            drop(cursor);
 580
 581            let mut fold_edits = Vec::with_capacity(inlay_edits.len());
 582            {
 583                let mut old_transforms = self
 584                    .snapshot
 585                    .transforms
 586                    .cursor::<Dimensions<InlayOffset, FoldOffset>>(());
 587                let mut new_transforms =
 588                    new_transforms.cursor::<Dimensions<InlayOffset, FoldOffset>>(());
 589
 590                for mut edit in inlay_edits {
 591                    old_transforms.seek(&edit.old.start, Bias::Left);
 592                    if old_transforms.item().is_some_and(|t| t.is_fold()) {
 593                        edit.old.start = old_transforms.start().0;
 594                    }
 595                    let old_start =
 596                        old_transforms.start().1.0 + (edit.old.start - old_transforms.start().0);
 597
 598                    old_transforms.seek_forward(&edit.old.end, Bias::Right);
 599                    if old_transforms.item().is_some_and(|t| t.is_fold()) {
 600                        old_transforms.next();
 601                        edit.old.end = old_transforms.start().0;
 602                    }
 603                    let old_end =
 604                        old_transforms.start().1.0 + (edit.old.end - old_transforms.start().0);
 605
 606                    new_transforms.seek(&edit.new.start, Bias::Left);
 607                    if new_transforms.item().is_some_and(|t| t.is_fold()) {
 608                        edit.new.start = new_transforms.start().0;
 609                    }
 610                    let new_start =
 611                        new_transforms.start().1.0 + (edit.new.start - new_transforms.start().0);
 612
 613                    new_transforms.seek_forward(&edit.new.end, Bias::Right);
 614                    if new_transforms.item().is_some_and(|t| t.is_fold()) {
 615                        new_transforms.next();
 616                        edit.new.end = new_transforms.start().0;
 617                    }
 618                    let new_end =
 619                        new_transforms.start().1.0 + (edit.new.end - new_transforms.start().0);
 620
 621                    fold_edits.push(FoldEdit {
 622                        old: FoldOffset(old_start)..FoldOffset(old_end),
 623                        new: FoldOffset(new_start)..FoldOffset(new_end),
 624                    });
 625                }
 626
 627                fold_edits = consolidate_fold_edits(fold_edits);
 628            }
 629
 630            self.snapshot.transforms = new_transforms;
 631            self.snapshot.inlay_snapshot = inlay_snapshot;
 632            self.snapshot.version += 1;
 633            fold_edits
 634        }
 635    }
 636}
 637
 638#[derive(Clone)]
 639pub struct FoldSnapshot {
 640    pub inlay_snapshot: InlaySnapshot,
 641    transforms: SumTree<Transform>,
 642    folds: SumTree<Fold>,
 643    fold_metadata_by_id: TreeMap<FoldId, FoldMetadata>,
 644    pub version: usize,
 645}
 646
 647impl Deref for FoldSnapshot {
 648    type Target = InlaySnapshot;
 649
 650    fn deref(&self) -> &Self::Target {
 651        &self.inlay_snapshot
 652    }
 653}
 654
 655impl FoldSnapshot {
 656    pub fn buffer(&self) -> &MultiBufferSnapshot {
 657        &self.inlay_snapshot.buffer
 658    }
 659
 660    #[ztracing::instrument(skip_all)]
 661    fn fold_width(&self, fold_id: &FoldId) -> Option<Pixels> {
 662        self.fold_metadata_by_id.get(fold_id)?.width
 663    }
 664
 665    #[cfg(test)]
 666    pub fn text(&self) -> String {
 667        self.chunks(
 668            FoldOffset(MultiBufferOffset(0))..self.len(),
 669            false,
 670            Highlights::default(),
 671        )
 672        .map(|c| c.text)
 673        .collect()
 674    }
 675
 676    #[cfg(test)]
 677    pub fn fold_count(&self) -> usize {
 678        self.folds.items(&self.inlay_snapshot.buffer).len()
 679    }
 680
 681    #[ztracing::instrument(skip_all)]
 682    pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> MBTextSummary {
 683        let mut summary = MBTextSummary::default();
 684
 685        let mut cursor = self
 686            .transforms
 687            .cursor::<Dimensions<FoldPoint, InlayPoint>>(());
 688        cursor.seek(&range.start, Bias::Right);
 689        if let Some(transform) = cursor.item() {
 690            let start_in_transform = range.start.0 - cursor.start().0.0;
 691            let end_in_transform = cmp::min(range.end, cursor.end().0).0 - cursor.start().0.0;
 692            if let Some(placeholder) = transform.placeholder.as_ref() {
 693                summary = MBTextSummary::from(
 694                    &placeholder.text
 695                        [start_in_transform.column as usize..end_in_transform.column as usize],
 696                );
 697            } else {
 698                let inlay_start = self
 699                    .inlay_snapshot
 700                    .to_offset(InlayPoint(cursor.start().1.0 + start_in_transform));
 701                let inlay_end = self
 702                    .inlay_snapshot
 703                    .to_offset(InlayPoint(cursor.start().1.0 + end_in_transform));
 704                summary = self
 705                    .inlay_snapshot
 706                    .text_summary_for_range(inlay_start..inlay_end);
 707            }
 708        }
 709
 710        if range.end > cursor.end().0 {
 711            cursor.next();
 712            summary += cursor
 713                .summary::<_, TransformSummary>(&range.end, Bias::Right)
 714                .output;
 715            if let Some(transform) = cursor.item() {
 716                let end_in_transform = range.end.0 - cursor.start().0.0;
 717                if let Some(placeholder) = transform.placeholder.as_ref() {
 718                    summary +=
 719                        MBTextSummary::from(&placeholder.text[..end_in_transform.column as usize]);
 720                } else {
 721                    let inlay_start = self.inlay_snapshot.to_offset(cursor.start().1);
 722                    let inlay_end = self
 723                        .inlay_snapshot
 724                        .to_offset(InlayPoint(cursor.start().1.0 + end_in_transform));
 725                    summary += self
 726                        .inlay_snapshot
 727                        .text_summary_for_range(inlay_start..inlay_end);
 728                }
 729            }
 730        }
 731
 732        summary
 733    }
 734
 735    #[ztracing::instrument(skip_all)]
 736    pub fn to_fold_point(&self, point: InlayPoint, bias: Bias) -> FoldPoint {
 737        let (start, end, item) = self
 738            .transforms
 739            .find::<Dimensions<InlayPoint, FoldPoint>, _>((), &point, Bias::Right);
 740        if item.is_some_and(|t| t.is_fold()) {
 741            if bias == Bias::Left || point == start.0 {
 742                start.1
 743            } else {
 744                end.1
 745            }
 746        } else {
 747            let overshoot = point.0 - start.0.0;
 748            FoldPoint(cmp::min(start.1.0 + overshoot, end.1.0))
 749        }
 750    }
 751
 752    #[ztracing::instrument(skip_all)]
 753    pub fn fold_point_cursor(&self) -> FoldPointCursor<'_> {
 754        let cursor = self
 755            .transforms
 756            .cursor::<Dimensions<InlayPoint, FoldPoint>>(());
 757        FoldPointCursor { cursor }
 758    }
 759
 760    #[ztracing::instrument(skip_all)]
 761    pub fn len(&self) -> FoldOffset {
 762        FoldOffset(self.transforms.summary().output.len)
 763    }
 764
 765    #[ztracing::instrument(skip_all)]
 766    pub fn line_len(&self, row: u32) -> u32 {
 767        let line_start = FoldPoint::new(row, 0).to_offset(self).0;
 768        let line_end = if row >= self.max_point().row() {
 769            self.len().0
 770        } else {
 771            FoldPoint::new(row + 1, 0).to_offset(self).0 - 1
 772        };
 773        (line_end - line_start) as u32
 774    }
 775
 776    #[ztracing::instrument(skip_all)]
 777    pub fn row_infos(&self, start_row: u32) -> FoldRows<'_> {
 778        if start_row > self.transforms.summary().output.lines.row {
 779            panic!("invalid display row {}", start_row);
 780        }
 781
 782        let fold_point = FoldPoint::new(start_row, 0);
 783        let mut cursor = self
 784            .transforms
 785            .cursor::<Dimensions<FoldPoint, InlayPoint>>(());
 786        cursor.seek(&fold_point, Bias::Left);
 787
 788        let overshoot = fold_point.0 - cursor.start().0.0;
 789        let inlay_point = InlayPoint(cursor.start().1.0 + overshoot);
 790        let input_rows = self.inlay_snapshot.row_infos(inlay_point.row());
 791
 792        FoldRows {
 793            fold_point,
 794            input_rows,
 795            cursor,
 796        }
 797    }
 798
 799    #[ztracing::instrument(skip_all)]
 800    pub fn max_point(&self) -> FoldPoint {
 801        FoldPoint(self.transforms.summary().output.lines)
 802    }
 803
 804    #[cfg(test)]
 805    pub fn longest_row(&self) -> u32 {
 806        self.transforms.summary().output.longest_row
 807    }
 808
 809    #[ztracing::instrument(skip_all)]
 810    pub fn folds_in_range<T>(&self, range: Range<T>) -> impl Iterator<Item = &Fold>
 811    where
 812        T: ToOffset,
 813    {
 814        let buffer = &self.inlay_snapshot.buffer;
 815        let range = range.start.to_offset(buffer)..range.end.to_offset(buffer);
 816        let mut folds = intersecting_folds(&self.inlay_snapshot, &self.folds, range, false);
 817        iter::from_fn(move || {
 818            let item = folds.item();
 819            folds.next();
 820            item
 821        })
 822    }
 823
 824    #[ztracing::instrument(skip_all)]
 825    pub fn intersects_fold<T>(&self, offset: T) -> bool
 826    where
 827        T: ToOffset,
 828    {
 829        let buffer_offset = offset.to_offset(&self.inlay_snapshot.buffer);
 830        let inlay_offset = self.inlay_snapshot.to_inlay_offset(buffer_offset);
 831        let (_, _, item) = self
 832            .transforms
 833            .find::<InlayOffset, _>((), &inlay_offset, Bias::Right);
 834        item.is_some_and(|t| t.placeholder.is_some())
 835    }
 836
 837    #[ztracing::instrument(skip_all)]
 838    pub fn is_line_folded(&self, buffer_row: MultiBufferRow) -> bool {
 839        let mut inlay_point = self
 840            .inlay_snapshot
 841            .to_inlay_point(Point::new(buffer_row.0, 0));
 842        let mut cursor = self.transforms.cursor::<InlayPoint>(());
 843        cursor.seek(&inlay_point, Bias::Right);
 844        loop {
 845            match cursor.item() {
 846                Some(transform) => {
 847                    let buffer_point = self.inlay_snapshot.to_buffer_point(inlay_point);
 848                    if buffer_point.row != buffer_row.0 {
 849                        return false;
 850                    } else if transform.placeholder.is_some() {
 851                        return true;
 852                    }
 853                }
 854                None => return false,
 855            }
 856
 857            if cursor.end().row() == inlay_point.row() {
 858                cursor.next();
 859            } else {
 860                inlay_point.0 += Point::new(1, 0);
 861                cursor.seek(&inlay_point, Bias::Right);
 862            }
 863        }
 864    }
 865
 866    #[ztracing::instrument(skip_all)]
 867    pub(crate) fn chunks<'a>(
 868        &'a self,
 869        range: Range<FoldOffset>,
 870        language_aware: bool,
 871        highlights: Highlights<'a>,
 872    ) -> FoldChunks<'a> {
 873        let mut transform_cursor = self
 874            .transforms
 875            .cursor::<Dimensions<FoldOffset, InlayOffset>>(());
 876        transform_cursor.seek(&range.start, Bias::Right);
 877
 878        let inlay_start = {
 879            let overshoot = range.start - transform_cursor.start().0;
 880            transform_cursor.start().1 + overshoot
 881        };
 882
 883        let transform_end = transform_cursor.end();
 884
 885        let inlay_end = if transform_cursor
 886            .item()
 887            .is_none_or(|transform| transform.is_fold())
 888        {
 889            inlay_start
 890        } else if range.end < transform_end.0 {
 891            let overshoot = range.end - transform_cursor.start().0;
 892            transform_cursor.start().1 + overshoot
 893        } else {
 894            transform_end.1
 895        };
 896
 897        FoldChunks {
 898            transform_cursor,
 899            inlay_chunks: self.inlay_snapshot.chunks(
 900                inlay_start..inlay_end,
 901                language_aware,
 902                highlights,
 903            ),
 904            inlay_chunk: None,
 905            inlay_offset: inlay_start,
 906            output_offset: range.start,
 907            max_output_offset: range.end,
 908        }
 909    }
 910
 911    #[ztracing::instrument(skip_all)]
 912    pub fn chars_at(&self, start: FoldPoint) -> impl '_ + Iterator<Item = char> {
 913        self.chunks(
 914            start.to_offset(self)..self.len(),
 915            false,
 916            Highlights::default(),
 917        )
 918        .flat_map(|chunk| chunk.text.chars())
 919    }
 920
 921    #[ztracing::instrument(skip_all)]
 922    pub fn chunks_at(&self, start: FoldPoint) -> FoldChunks<'_> {
 923        self.chunks(
 924            start.to_offset(self)..self.len(),
 925            false,
 926            Highlights::default(),
 927        )
 928    }
 929
 930    #[cfg(test)]
 931    #[ztracing::instrument(skip_all)]
 932    pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
 933        if offset > self.len() {
 934            self.len()
 935        } else {
 936            self.clip_point(offset.to_point(self), bias).to_offset(self)
 937        }
 938    }
 939
 940    #[ztracing::instrument(skip_all)]
 941    pub fn clip_point(&self, point: FoldPoint, bias: Bias) -> FoldPoint {
 942        let (start, end, item) = self
 943            .transforms
 944            .find::<Dimensions<FoldPoint, InlayPoint>, _>((), &point, Bias::Right);
 945        if let Some(transform) = item {
 946            let transform_start = start.0.0;
 947            if transform.placeholder.is_some() {
 948                if point.0 == transform_start || matches!(bias, Bias::Left) {
 949                    FoldPoint(transform_start)
 950                } else {
 951                    FoldPoint(end.0.0)
 952                }
 953            } else {
 954                let overshoot = InlayPoint(point.0 - transform_start);
 955                let inlay_point = start.1 + overshoot;
 956                let clipped_inlay_point = self.inlay_snapshot.clip_point(inlay_point, bias);
 957                FoldPoint(start.0.0 + (clipped_inlay_point - start.1).0)
 958            }
 959        } else {
 960            FoldPoint(self.transforms.summary().output.lines)
 961        }
 962    }
 963}
 964
 965pub struct FoldPointCursor<'transforms> {
 966    cursor: Cursor<'transforms, 'static, Transform, Dimensions<InlayPoint, FoldPoint>>,
 967}
 968
 969impl FoldPointCursor<'_> {
 970    #[ztracing::instrument(skip_all)]
 971    pub fn map(&mut self, point: InlayPoint, bias: Bias) -> FoldPoint {
 972        let cursor = &mut self.cursor;
 973        if cursor.did_seek() {
 974            cursor.seek_forward(&point, Bias::Right);
 975        } else {
 976            cursor.seek(&point, Bias::Right);
 977        }
 978        if cursor.item().is_some_and(|t| t.is_fold()) {
 979            if bias == Bias::Left || point == cursor.start().0 {
 980                cursor.start().1
 981            } else {
 982                cursor.end().1
 983            }
 984        } else {
 985            let overshoot = point.0 - cursor.start().0.0;
 986            FoldPoint(cmp::min(cursor.start().1.0 + overshoot, cursor.end().1.0))
 987        }
 988    }
 989}
 990
 991fn push_isomorphic(transforms: &mut SumTree<Transform>, summary: MBTextSummary) {
 992    let mut did_merge = false;
 993    transforms.update_last(
 994        |last| {
 995            if !last.is_fold() {
 996                last.summary.input += summary;
 997                last.summary.output += summary;
 998                did_merge = true;
 999            }
1000        },
1001        (),
1002    );
1003    if !did_merge {
1004        transforms.push(
1005            Transform {
1006                summary: TransformSummary {
1007                    input: summary,
1008                    output: summary,
1009                },
1010                placeholder: None,
1011            },
1012            (),
1013        )
1014    }
1015}
1016
1017fn intersecting_folds<'a>(
1018    inlay_snapshot: &'a InlaySnapshot,
1019    folds: &'a SumTree<Fold>,
1020    range: Range<MultiBufferOffset>,
1021    inclusive: bool,
1022) -> FilterCursor<'a, 'a, impl 'a + FnMut(&FoldSummary) -> bool, Fold, MultiBufferOffset> {
1023    let buffer = &inlay_snapshot.buffer;
1024    let start = buffer.anchor_before(range.start.to_offset(buffer));
1025    let end = buffer.anchor_after(range.end.to_offset(buffer));
1026    let mut cursor = folds.filter::<_, MultiBufferOffset>(buffer, move |summary| {
1027        let start_cmp = start.cmp(&summary.max_end, buffer);
1028        let end_cmp = end.cmp(&summary.min_start, buffer);
1029
1030        if inclusive {
1031            start_cmp <= Ordering::Equal && end_cmp >= Ordering::Equal
1032        } else {
1033            start_cmp == Ordering::Less && end_cmp == Ordering::Greater
1034        }
1035    });
1036    cursor.next();
1037    cursor
1038}
1039
1040fn consolidate_inlay_edits(mut edits: Vec<InlayEdit>) -> Vec<InlayEdit> {
1041    edits.sort_unstable_by(|a, b| {
1042        a.old
1043            .start
1044            .cmp(&b.old.start)
1045            .then_with(|| b.old.end.cmp(&a.old.end))
1046    });
1047
1048    let _old_alloc_ptr = edits.as_ptr();
1049    let mut inlay_edits = edits.into_iter();
1050
1051    if let Some(mut first_edit) = inlay_edits.next() {
1052        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
1053        #[allow(clippy::filter_map_identity)]
1054        let mut v: Vec<_> = inlay_edits
1055            .scan(&mut first_edit, |prev_edit, edit| {
1056                if prev_edit.old.end >= edit.old.start {
1057                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
1058                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
1059                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
1060                    Some(None) // Skip this edit, it's merged
1061                } else {
1062                    let prev = std::mem::replace(*prev_edit, edit);
1063                    Some(Some(prev)) // Yield the previous edit
1064                }
1065            })
1066            .filter_map(|x| x)
1067            .collect();
1068        v.push(first_edit.clone());
1069        debug_assert_eq!(_old_alloc_ptr, v.as_ptr(), "Inlay edits were reallocated");
1070        v
1071    } else {
1072        vec![]
1073    }
1074}
1075
1076fn consolidate_fold_edits(mut edits: Vec<FoldEdit>) -> Vec<FoldEdit> {
1077    edits.sort_unstable_by(|a, b| {
1078        a.old
1079            .start
1080            .cmp(&b.old.start)
1081            .then_with(|| b.old.end.cmp(&a.old.end))
1082    });
1083    let _old_alloc_ptr = edits.as_ptr();
1084    let mut fold_edits = edits.into_iter();
1085
1086    if let Some(mut first_edit) = fold_edits.next() {
1087        // This code relies on reusing allocations from the Vec<_> - at the time of writing .flatten() prevents them.
1088        #[allow(clippy::filter_map_identity)]
1089        let mut v: Vec<_> = fold_edits
1090            .scan(&mut first_edit, |prev_edit, edit| {
1091                if prev_edit.old.end >= edit.old.start {
1092                    prev_edit.old.end = prev_edit.old.end.max(edit.old.end);
1093                    prev_edit.new.start = prev_edit.new.start.min(edit.new.start);
1094                    prev_edit.new.end = prev_edit.new.end.max(edit.new.end);
1095                    Some(None) // Skip this edit, it's merged
1096                } else {
1097                    let prev = std::mem::replace(*prev_edit, edit);
1098                    Some(Some(prev)) // Yield the previous edit
1099                }
1100            })
1101            .filter_map(|x| x)
1102            .collect();
1103        v.push(first_edit.clone());
1104        v
1105    } else {
1106        vec![]
1107    }
1108}
1109
1110#[derive(Clone, Debug, Default)]
1111struct Transform {
1112    summary: TransformSummary,
1113    placeholder: Option<TransformPlaceholder>,
1114}
1115
1116#[derive(Clone, Debug)]
1117struct TransformPlaceholder {
1118    text: &'static str,
1119    chars: u128,
1120    renderer: ChunkRenderer,
1121}
1122
1123impl Transform {
1124    fn is_fold(&self) -> bool {
1125        self.placeholder.is_some()
1126    }
1127}
1128
1129#[derive(Clone, Debug, Default, Eq, PartialEq)]
1130struct TransformSummary {
1131    output: MBTextSummary,
1132    input: MBTextSummary,
1133}
1134
1135impl sum_tree::Item for Transform {
1136    type Summary = TransformSummary;
1137
1138    fn summary(&self, _cx: ()) -> Self::Summary {
1139        self.summary.clone()
1140    }
1141}
1142
1143impl sum_tree::ContextLessSummary for TransformSummary {
1144    fn zero() -> Self {
1145        Default::default()
1146    }
1147
1148    fn add_summary(&mut self, other: &Self) {
1149        self.input += other.input;
1150        self.output += other.output;
1151    }
1152}
1153
1154#[derive(Copy, Clone, Eq, PartialEq, Debug, Default, Ord, PartialOrd, Hash)]
1155pub struct FoldId(pub(super) usize);
1156
1157impl From<FoldId> for ElementId {
1158    fn from(val: FoldId) -> Self {
1159        val.0.into()
1160    }
1161}
1162
1163#[derive(Clone, Debug, Eq, PartialEq)]
1164pub struct Fold {
1165    pub id: FoldId,
1166    pub range: FoldRange,
1167    pub placeholder: FoldPlaceholder,
1168}
1169
1170#[derive(Clone, Debug, Eq, PartialEq)]
1171pub struct FoldRange(Range<Anchor>);
1172
1173impl Deref for FoldRange {
1174    type Target = Range<Anchor>;
1175
1176    fn deref(&self) -> &Self::Target {
1177        &self.0
1178    }
1179}
1180
1181impl DerefMut for FoldRange {
1182    fn deref_mut(&mut self) -> &mut Self::Target {
1183        &mut self.0
1184    }
1185}
1186
1187impl Default for FoldRange {
1188    fn default() -> Self {
1189        Self(Anchor::min()..Anchor::max())
1190    }
1191}
1192
1193#[derive(Clone, Debug)]
1194struct FoldMetadata {
1195    range: FoldRange,
1196    width: Option<Pixels>,
1197}
1198
1199impl sum_tree::Item for Fold {
1200    type Summary = FoldSummary;
1201
1202    fn summary(&self, _cx: &MultiBufferSnapshot) -> Self::Summary {
1203        FoldSummary {
1204            start: self.range.start,
1205            end: self.range.end,
1206            min_start: self.range.start,
1207            max_end: self.range.end,
1208            count: 1,
1209        }
1210    }
1211}
1212
1213#[derive(Clone, Debug)]
1214pub struct FoldSummary {
1215    start: Anchor,
1216    end: Anchor,
1217    min_start: Anchor,
1218    max_end: Anchor,
1219    count: usize,
1220}
1221
1222impl Default for FoldSummary {
1223    fn default() -> Self {
1224        Self {
1225            start: Anchor::min(),
1226            end: Anchor::max(),
1227            min_start: Anchor::max(),
1228            max_end: Anchor::min(),
1229            count: 0,
1230        }
1231    }
1232}
1233
1234impl sum_tree::Summary for FoldSummary {
1235    type Context<'a> = &'a MultiBufferSnapshot;
1236
1237    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1238        Default::default()
1239    }
1240
1241    fn add_summary(&mut self, other: &Self, buffer: Self::Context<'_>) {
1242        if other.min_start.cmp(&self.min_start, buffer) == Ordering::Less {
1243            self.min_start = other.min_start;
1244        }
1245        if other.max_end.cmp(&self.max_end, buffer) == Ordering::Greater {
1246            self.max_end = other.max_end;
1247        }
1248
1249        #[cfg(debug_assertions)]
1250        {
1251            let start_comparison = self.start.cmp(&other.start, buffer);
1252            assert!(start_comparison <= Ordering::Equal);
1253            if start_comparison == Ordering::Equal {
1254                assert!(self.end.cmp(&other.end, buffer) >= Ordering::Equal);
1255            }
1256        }
1257
1258        self.start = other.start;
1259        self.end = other.end;
1260        self.count += other.count;
1261    }
1262}
1263
1264impl<'a> sum_tree::Dimension<'a, FoldSummary> for FoldRange {
1265    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1266        Default::default()
1267    }
1268
1269    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1270        self.0.start = summary.start;
1271        self.0.end = summary.end;
1272    }
1273}
1274
1275impl sum_tree::SeekTarget<'_, FoldSummary, FoldRange> for FoldRange {
1276    fn cmp(&self, other: &Self, buffer: &MultiBufferSnapshot) -> Ordering {
1277        AnchorRangeExt::cmp(&self.0, &other.0, buffer)
1278    }
1279}
1280
1281impl<'a> sum_tree::Dimension<'a, FoldSummary> for MultiBufferOffset {
1282    fn zero(_cx: &MultiBufferSnapshot) -> Self {
1283        Default::default()
1284    }
1285
1286    fn add_summary(&mut self, summary: &'a FoldSummary, _: &MultiBufferSnapshot) {
1287        *self += summary.count;
1288    }
1289}
1290
1291#[derive(Clone)]
1292pub struct FoldRows<'a> {
1293    cursor: Cursor<'a, 'static, Transform, Dimensions<FoldPoint, InlayPoint>>,
1294    input_rows: InlayBufferRows<'a>,
1295    fold_point: FoldPoint,
1296}
1297
1298impl FoldRows<'_> {
1299    #[ztracing::instrument(skip_all)]
1300    pub(crate) fn seek(&mut self, row: u32) {
1301        let fold_point = FoldPoint::new(row, 0);
1302        self.cursor.seek(&fold_point, Bias::Left);
1303        let overshoot = fold_point.0 - self.cursor.start().0.0;
1304        let inlay_point = InlayPoint(self.cursor.start().1.0 + overshoot);
1305        self.input_rows.seek(inlay_point.row());
1306        self.fold_point = fold_point;
1307    }
1308}
1309
1310impl Iterator for FoldRows<'_> {
1311    type Item = RowInfo;
1312
1313    #[ztracing::instrument(skip_all)]
1314    fn next(&mut self) -> Option<Self::Item> {
1315        let mut traversed_fold = false;
1316        while self.fold_point > self.cursor.end().0 {
1317            self.cursor.next();
1318            traversed_fold = true;
1319            if self.cursor.item().is_none() {
1320                break;
1321            }
1322        }
1323
1324        if self.cursor.item().is_some() {
1325            if traversed_fold {
1326                self.input_rows.seek(self.cursor.start().1.0.row);
1327                self.input_rows.next();
1328            }
1329            *self.fold_point.row_mut() += 1;
1330            self.input_rows.next()
1331        } else {
1332            None
1333        }
1334    }
1335}
1336
1337/// A chunk of a buffer's text, along with its syntax highlight and
1338/// diagnostic status.
1339#[derive(Clone, Debug, Default)]
1340pub struct Chunk<'a> {
1341    /// The text of the chunk.
1342    pub text: &'a str,
1343    /// The syntax highlighting style of the chunk.
1344    pub syntax_highlight_id: Option<HighlightId>,
1345    /// The highlight style that has been applied to this chunk in
1346    /// the editor.
1347    pub highlight_style: Option<HighlightStyle>,
1348    /// The severity of diagnostic associated with this chunk, if any.
1349    pub diagnostic_severity: Option<lsp::DiagnosticSeverity>,
1350    /// Whether this chunk of text is marked as unnecessary.
1351    pub is_unnecessary: bool,
1352    /// Whether this chunk of text should be underlined.
1353    pub underline: bool,
1354    /// Whether this chunk of text was originally a tab character.
1355    pub is_tab: bool,
1356    /// Whether this chunk of text was originally a tab character.
1357    pub is_inlay: bool,
1358    /// An optional recipe for how the chunk should be presented.
1359    pub renderer: Option<ChunkRenderer>,
1360    /// Bitmap of tab character locations in chunk
1361    pub tabs: u128,
1362    /// Bitmap of character locations in chunk
1363    pub chars: u128,
1364}
1365
1366#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
1367pub enum ChunkRendererId {
1368    Fold(FoldId),
1369    Inlay(InlayId),
1370}
1371
1372/// A recipe for how the chunk should be presented.
1373#[derive(Clone)]
1374pub struct ChunkRenderer {
1375    /// The id of the renderer associated with this chunk.
1376    pub id: ChunkRendererId,
1377    /// Creates a custom element to represent this chunk.
1378    pub render: Arc<dyn Send + Sync + Fn(&mut ChunkRendererContext) -> AnyElement>,
1379    /// If true, the element is constrained to the shaped width of the text.
1380    pub constrain_width: bool,
1381    /// The width of the element, as measured during the last layout pass.
1382    ///
1383    /// This is None if the element has not been laid out yet.
1384    pub measured_width: Option<Pixels>,
1385}
1386
1387pub struct ChunkRendererContext<'a, 'b> {
1388    pub window: &'a mut Window,
1389    pub context: &'b mut App,
1390    pub max_width: Pixels,
1391}
1392
1393impl fmt::Debug for ChunkRenderer {
1394    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1395        f.debug_struct("ChunkRenderer")
1396            .field("constrain_width", &self.constrain_width)
1397            .finish()
1398    }
1399}
1400
1401impl Deref for ChunkRendererContext<'_, '_> {
1402    type Target = App;
1403
1404    fn deref(&self) -> &Self::Target {
1405        self.context
1406    }
1407}
1408
1409impl DerefMut for ChunkRendererContext<'_, '_> {
1410    fn deref_mut(&mut self) -> &mut Self::Target {
1411        self.context
1412    }
1413}
1414
1415pub struct FoldChunks<'a> {
1416    transform_cursor: Cursor<'a, 'static, Transform, Dimensions<FoldOffset, InlayOffset>>,
1417    inlay_chunks: InlayChunks<'a>,
1418    inlay_chunk: Option<(InlayOffset, InlayChunk<'a>)>,
1419    inlay_offset: InlayOffset,
1420    output_offset: FoldOffset,
1421    max_output_offset: FoldOffset,
1422}
1423
1424impl FoldChunks<'_> {
1425    #[ztracing::instrument(skip_all)]
1426    pub(crate) fn seek(&mut self, range: Range<FoldOffset>) {
1427        self.transform_cursor.seek(&range.start, Bias::Right);
1428
1429        let inlay_start = {
1430            let overshoot = range.start - self.transform_cursor.start().0;
1431            self.transform_cursor.start().1 + overshoot
1432        };
1433
1434        let transform_end = self.transform_cursor.end();
1435
1436        let inlay_end = if self
1437            .transform_cursor
1438            .item()
1439            .is_none_or(|transform| transform.is_fold())
1440        {
1441            inlay_start
1442        } else if range.end < transform_end.0 {
1443            let overshoot = range.end - self.transform_cursor.start().0;
1444            self.transform_cursor.start().1 + overshoot
1445        } else {
1446            transform_end.1
1447        };
1448
1449        self.inlay_chunks.seek(inlay_start..inlay_end);
1450        self.inlay_chunk = None;
1451        self.inlay_offset = inlay_start;
1452        self.output_offset = range.start;
1453        self.max_output_offset = range.end;
1454    }
1455}
1456
1457impl<'a> Iterator for FoldChunks<'a> {
1458    type Item = Chunk<'a>;
1459
1460    #[ztracing::instrument(skip_all)]
1461    fn next(&mut self) -> Option<Self::Item> {
1462        if self.output_offset >= self.max_output_offset {
1463            return None;
1464        }
1465
1466        let transform = self.transform_cursor.item()?;
1467
1468        // If we're in a fold, then return the fold's display text and
1469        // advance the transform and buffer cursors to the end of the fold.
1470        if let Some(placeholder) = transform.placeholder.as_ref() {
1471            self.inlay_chunk.take();
1472            self.inlay_offset += InlayOffset(transform.summary.input.len);
1473
1474            while self.inlay_offset >= self.transform_cursor.end().1
1475                && self.transform_cursor.item().is_some()
1476            {
1477                self.transform_cursor.next();
1478            }
1479
1480            self.output_offset.0 += placeholder.text.len();
1481            return Some(Chunk {
1482                text: placeholder.text,
1483                chars: placeholder.chars,
1484                renderer: Some(placeholder.renderer.clone()),
1485                ..Default::default()
1486            });
1487        }
1488
1489        // When we reach a non-fold region, seek the underlying text
1490        // chunk iterator to the next unfolded range.
1491        if self.inlay_offset == self.transform_cursor.start().1
1492            && self.inlay_chunks.offset() != self.inlay_offset
1493        {
1494            let transform_start = self.transform_cursor.start();
1495            let transform_end = self.transform_cursor.end();
1496            let inlay_end = if self.max_output_offset < transform_end.0 {
1497                let overshoot = self.max_output_offset - transform_start.0;
1498                transform_start.1 + overshoot
1499            } else {
1500                transform_end.1
1501            };
1502
1503            self.inlay_chunks.seek(self.inlay_offset..inlay_end);
1504        }
1505
1506        // Retrieve a chunk from the current location in the buffer.
1507        if self.inlay_chunk.is_none() {
1508            let chunk_offset = self.inlay_chunks.offset();
1509            self.inlay_chunk = self.inlay_chunks.next().map(|chunk| (chunk_offset, chunk));
1510        }
1511
1512        // Otherwise, take a chunk from the buffer's text.
1513        if let Some((buffer_chunk_start, mut inlay_chunk)) = self.inlay_chunk.clone() {
1514            let chunk = &mut inlay_chunk.chunk;
1515            let buffer_chunk_end = buffer_chunk_start + chunk.text.len();
1516            let transform_end = self.transform_cursor.end().1;
1517            let chunk_end = buffer_chunk_end.min(transform_end);
1518
1519            let bit_start = self.inlay_offset - buffer_chunk_start;
1520            let bit_end = chunk_end - buffer_chunk_start;
1521            chunk.text = &chunk.text[bit_start..bit_end];
1522
1523            let bit_end = chunk_end - buffer_chunk_start;
1524            let mask = 1u128.unbounded_shl(bit_end as u32).wrapping_sub(1);
1525
1526            chunk.tabs = (chunk.tabs >> bit_start) & mask;
1527            chunk.chars = (chunk.chars >> bit_start) & mask;
1528
1529            if chunk_end == transform_end {
1530                self.transform_cursor.next();
1531            } else if chunk_end == buffer_chunk_end {
1532                self.inlay_chunk.take();
1533            }
1534
1535            self.inlay_offset = chunk_end;
1536            self.output_offset.0 += chunk.text.len();
1537            return Some(Chunk {
1538                text: chunk.text,
1539                tabs: chunk.tabs,
1540                chars: chunk.chars,
1541                syntax_highlight_id: chunk.syntax_highlight_id,
1542                highlight_style: chunk.highlight_style,
1543                diagnostic_severity: chunk.diagnostic_severity,
1544                is_unnecessary: chunk.is_unnecessary,
1545                is_tab: chunk.is_tab,
1546                is_inlay: chunk.is_inlay,
1547                underline: chunk.underline,
1548                renderer: inlay_chunk.renderer,
1549            });
1550        }
1551
1552        None
1553    }
1554}
1555
1556#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
1557pub struct FoldOffset(pub MultiBufferOffset);
1558
1559impl FoldOffset {
1560    #[ztracing::instrument(skip_all)]
1561    pub fn to_point(self, snapshot: &FoldSnapshot) -> FoldPoint {
1562        let (start, _, item) = snapshot
1563            .transforms
1564            .find::<Dimensions<FoldOffset, TransformSummary>, _>((), &self, Bias::Right);
1565        let overshoot = if item.is_none_or(|t| t.is_fold()) {
1566            Point::new(0, (self.0 - start.0.0) as u32)
1567        } else {
1568            let inlay_offset = start.1.input.len + (self - start.0);
1569            let inlay_point = snapshot.inlay_snapshot.to_point(InlayOffset(inlay_offset));
1570            inlay_point.0 - start.1.input.lines
1571        };
1572        FoldPoint(start.1.output.lines + overshoot)
1573    }
1574
1575    #[cfg(test)]
1576    #[ztracing::instrument(skip_all)]
1577    pub fn to_inlay_offset(self, snapshot: &FoldSnapshot) -> InlayOffset {
1578        let (start, _, _) = snapshot
1579            .transforms
1580            .find::<Dimensions<FoldOffset, InlayOffset>, _>((), &self, Bias::Right);
1581        let overshoot = self - start.0;
1582        InlayOffset(start.1.0 + overshoot)
1583    }
1584}
1585
1586impl Add for FoldOffset {
1587    type Output = Self;
1588
1589    fn add(self, rhs: Self) -> Self::Output {
1590        Self(self.0 + rhs.0)
1591    }
1592}
1593
1594impl Sub for FoldOffset {
1595    type Output = <MultiBufferOffset as Sub>::Output;
1596
1597    fn sub(self, rhs: Self) -> Self::Output {
1598        self.0 - rhs.0
1599    }
1600}
1601
1602impl<T> SubAssign<T> for FoldOffset
1603where
1604    MultiBufferOffset: SubAssign<T>,
1605{
1606    fn sub_assign(&mut self, rhs: T) {
1607        self.0 -= rhs;
1608    }
1609}
1610
1611impl<T> Add<T> for FoldOffset
1612where
1613    MultiBufferOffset: Add<T, Output = MultiBufferOffset>,
1614{
1615    type Output = Self;
1616
1617    fn add(self, rhs: T) -> Self::Output {
1618        Self(self.0 + rhs)
1619    }
1620}
1621
1622impl AddAssign for FoldOffset {
1623    fn add_assign(&mut self, rhs: Self) {
1624        self.0 += rhs.0;
1625    }
1626}
1627
1628impl<T> AddAssign<T> for FoldOffset
1629where
1630    MultiBufferOffset: AddAssign<T>,
1631{
1632    fn add_assign(&mut self, rhs: T) {
1633        self.0 += rhs;
1634    }
1635}
1636
1637impl<'a> sum_tree::Dimension<'a, TransformSummary> for FoldOffset {
1638    fn zero(_cx: ()) -> Self {
1639        Default::default()
1640    }
1641
1642    fn add_summary(&mut self, summary: &'a TransformSummary, _: ()) {
1643        self.0 += summary.output.len;
1644    }
1645}
1646
1647impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayPoint {
1648    fn zero(_cx: ()) -> Self {
1649        Default::default()
1650    }
1651
1652    fn add_summary(&mut self, summary: &'a TransformSummary, _: ()) {
1653        self.0 += &summary.input.lines;
1654    }
1655}
1656
1657impl<'a> sum_tree::Dimension<'a, TransformSummary> for InlayOffset {
1658    fn zero(_cx: ()) -> Self {
1659        Default::default()
1660    }
1661
1662    fn add_summary(&mut self, summary: &'a TransformSummary, _: ()) {
1663        self.0 += summary.input.len;
1664    }
1665}
1666
1667pub type FoldEdit = Edit<FoldOffset>;
1668
1669#[cfg(test)]
1670mod tests {
1671    use super::*;
1672    use crate::{MultiBuffer, ToPoint, display_map::inlay_map::InlayMap};
1673    use Bias::{Left, Right};
1674    use collections::HashSet;
1675    use rand::prelude::*;
1676    use settings::SettingsStore;
1677    use std::{env, mem};
1678    use text::Patch;
1679    use util::RandomCharIter;
1680    use util::test::sample_text;
1681
1682    #[gpui::test]
1683    fn test_basic_folds(cx: &mut gpui::App) {
1684        init_test(cx);
1685        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1686        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1687        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1688        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1689        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1690
1691        let (mut writer, _, _) = map.write(inlay_snapshot, vec![]);
1692        let (snapshot2, edits) = writer.fold(vec![
1693            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1694            (Point::new(2, 4)..Point::new(4, 1), FoldPlaceholder::test()),
1695        ]);
1696        assert_eq!(snapshot2.text(), "aa⋯cc⋯eeeee");
1697        assert_eq!(
1698            edits,
1699            &[
1700                FoldEdit {
1701                    old: FoldOffset(MultiBufferOffset(2))..FoldOffset(MultiBufferOffset(16)),
1702                    new: FoldOffset(MultiBufferOffset(2))..FoldOffset(MultiBufferOffset(5)),
1703                },
1704                FoldEdit {
1705                    old: FoldOffset(MultiBufferOffset(18))..FoldOffset(MultiBufferOffset(29)),
1706                    new: FoldOffset(MultiBufferOffset(7))..FoldOffset(MultiBufferOffset(10)),
1707                },
1708            ]
1709        );
1710
1711        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1712            buffer.edit(
1713                vec![
1714                    (Point::new(0, 0)..Point::new(0, 1), "123"),
1715                    (Point::new(2, 3)..Point::new(2, 3), "123"),
1716                ],
1717                None,
1718                cx,
1719            );
1720            buffer.snapshot(cx)
1721        });
1722
1723        let (inlay_snapshot, inlay_edits) =
1724            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1725        let (snapshot3, edits) = map.read(inlay_snapshot, inlay_edits);
1726        assert_eq!(snapshot3.text(), "123a⋯c123c⋯eeeee");
1727        assert_eq!(
1728            edits,
1729            &[
1730                FoldEdit {
1731                    old: FoldOffset(MultiBufferOffset(0))..FoldOffset(MultiBufferOffset(1)),
1732                    new: FoldOffset(MultiBufferOffset(0))..FoldOffset(MultiBufferOffset(3)),
1733                },
1734                FoldEdit {
1735                    old: FoldOffset(MultiBufferOffset(6))..FoldOffset(MultiBufferOffset(6)),
1736                    new: FoldOffset(MultiBufferOffset(8))..FoldOffset(MultiBufferOffset(11)),
1737                },
1738            ]
1739        );
1740
1741        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1742            buffer.edit([(Point::new(2, 6)..Point::new(4, 3), "456")], None, cx);
1743            buffer.snapshot(cx)
1744        });
1745        let (inlay_snapshot, inlay_edits) =
1746            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1747        let (snapshot4, _) = map.read(inlay_snapshot.clone(), inlay_edits);
1748        assert_eq!(snapshot4.text(), "123a⋯c123456eee");
1749
1750        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1751        writer.unfold_intersecting(Some(Point::new(0, 4)..Point::new(0, 4)), false);
1752        let (snapshot5, _) = map.read(inlay_snapshot.clone(), vec![]);
1753        assert_eq!(snapshot5.text(), "123a⋯c123456eee");
1754
1755        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1756        writer.unfold_intersecting(Some(Point::new(0, 4)..Point::new(0, 4)), true);
1757        let (snapshot6, _) = map.read(inlay_snapshot, vec![]);
1758        assert_eq!(snapshot6.text(), "123aaaaa\nbbbbbb\nccc123456eee");
1759    }
1760
1761    #[gpui::test]
1762    fn test_adjacent_folds(cx: &mut gpui::App) {
1763        init_test(cx);
1764        let buffer = MultiBuffer::build_simple("abcdefghijkl", cx);
1765        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1766        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1767        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1768
1769        {
1770            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1771
1772            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1773            writer.fold(vec![(
1774                MultiBufferOffset(5)..MultiBufferOffset(8),
1775                FoldPlaceholder::test(),
1776            )]);
1777            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1778            assert_eq!(snapshot.text(), "abcde⋯ijkl");
1779
1780            // Create an fold adjacent to the start of the first fold.
1781            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1782            writer.fold(vec![
1783                (
1784                    MultiBufferOffset(0)..MultiBufferOffset(1),
1785                    FoldPlaceholder::test(),
1786                ),
1787                (
1788                    MultiBufferOffset(2)..MultiBufferOffset(5),
1789                    FoldPlaceholder::test(),
1790                ),
1791            ]);
1792            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1793            assert_eq!(snapshot.text(), "⋯b⋯ijkl");
1794
1795            // Create an fold adjacent to the end of the first fold.
1796            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1797            writer.fold(vec![
1798                (
1799                    MultiBufferOffset(11)..MultiBufferOffset(11),
1800                    FoldPlaceholder::test(),
1801                ),
1802                (
1803                    MultiBufferOffset(8)..MultiBufferOffset(10),
1804                    FoldPlaceholder::test(),
1805                ),
1806            ]);
1807            let (snapshot, _) = map.read(inlay_snapshot.clone(), vec![]);
1808            assert_eq!(snapshot.text(), "⋯b⋯kl");
1809        }
1810
1811        {
1812            let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1813
1814            // Create two adjacent folds.
1815            let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1816            writer.fold(vec![
1817                (
1818                    MultiBufferOffset(0)..MultiBufferOffset(2),
1819                    FoldPlaceholder::test(),
1820                ),
1821                (
1822                    MultiBufferOffset(2)..MultiBufferOffset(5),
1823                    FoldPlaceholder::test(),
1824                ),
1825            ]);
1826            let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1827            assert_eq!(snapshot.text(), "⋯fghijkl");
1828
1829            // Edit within one of the folds.
1830            let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1831                buffer.edit(
1832                    [(MultiBufferOffset(0)..MultiBufferOffset(1), "12345")],
1833                    None,
1834                    cx,
1835                );
1836                buffer.snapshot(cx)
1837            });
1838            let (inlay_snapshot, inlay_edits) =
1839                inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1840            let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1841            assert_eq!(snapshot.text(), "12345⋯fghijkl");
1842        }
1843    }
1844
1845    #[gpui::test]
1846    fn test_overlapping_folds(cx: &mut gpui::App) {
1847        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1848        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1849        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1850        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1851        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1852        writer.fold(vec![
1853            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1854            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1855            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1856            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1857        ]);
1858        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1859        assert_eq!(snapshot.text(), "aa⋯eeeee");
1860    }
1861
1862    #[gpui::test]
1863    fn test_merging_folds_via_edit(cx: &mut gpui::App) {
1864        init_test(cx);
1865        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1866        let subscription = buffer.update(cx, |buffer, _| buffer.subscribe());
1867        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1868        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot);
1869        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1870
1871        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1872        writer.fold(vec![
1873            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1874            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1875        ]);
1876        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1877        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee");
1878
1879        let buffer_snapshot = buffer.update(cx, |buffer, cx| {
1880            buffer.edit([(Point::new(2, 2)..Point::new(3, 1), "")], None, cx);
1881            buffer.snapshot(cx)
1882        });
1883        let (inlay_snapshot, inlay_edits) =
1884            inlay_map.sync(buffer_snapshot, subscription.consume().into_inner());
1885        let (snapshot, _) = map.read(inlay_snapshot, inlay_edits);
1886        assert_eq!(snapshot.text(), "aa⋯eeeee");
1887    }
1888
1889    #[gpui::test]
1890    fn test_folds_in_range(cx: &mut gpui::App) {
1891        let buffer = MultiBuffer::build_simple(&sample_text(5, 6, 'a'), cx);
1892        let buffer_snapshot = buffer.read(cx).snapshot(cx);
1893        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1894        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1895
1896        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
1897        writer.fold(vec![
1898            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
1899            (Point::new(0, 4)..Point::new(1, 0), FoldPlaceholder::test()),
1900            (Point::new(1, 2)..Point::new(3, 2), FoldPlaceholder::test()),
1901            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
1902        ]);
1903        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
1904        let fold_ranges = snapshot
1905            .folds_in_range(Point::new(1, 0)..Point::new(1, 3))
1906            .map(|fold| {
1907                fold.range.start.to_point(&buffer_snapshot)
1908                    ..fold.range.end.to_point(&buffer_snapshot)
1909            })
1910            .collect::<Vec<_>>();
1911        assert_eq!(
1912            fold_ranges,
1913            vec![
1914                Point::new(0, 2)..Point::new(2, 2),
1915                Point::new(1, 2)..Point::new(3, 2)
1916            ]
1917        );
1918    }
1919
1920    #[gpui::test(iterations = 100)]
1921    fn test_random_folds(cx: &mut gpui::App, mut rng: StdRng) {
1922        init_test(cx);
1923        let operations = env::var("OPERATIONS")
1924            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
1925            .unwrap_or(10);
1926
1927        let len = rng.random_range(0..10);
1928        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
1929        let buffer = if rng.random() {
1930            MultiBuffer::build_simple(&text, cx)
1931        } else {
1932            MultiBuffer::build_random(&mut rng, cx)
1933        };
1934        let mut buffer_snapshot = buffer.read(cx).snapshot(cx);
1935        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
1936        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
1937
1938        let (mut initial_snapshot, _) = map.read(inlay_snapshot, vec![]);
1939        let mut snapshot_edits = Vec::new();
1940
1941        let mut next_inlay_id = 0;
1942        for _ in 0..operations {
1943            log::info!("text: {:?}", buffer_snapshot.text());
1944            let mut buffer_edits = Vec::new();
1945            let mut inlay_edits = Vec::new();
1946            match rng.random_range(0..=100) {
1947                0..=39 => {
1948                    snapshot_edits.extend(map.randomly_mutate(&mut rng));
1949                }
1950                40..=59 => {
1951                    let (_, edits) = inlay_map.randomly_mutate(&mut next_inlay_id, &mut rng);
1952                    inlay_edits = edits;
1953                }
1954                _ => buffer.update(cx, |buffer, cx| {
1955                    let subscription = buffer.subscribe();
1956                    let edit_count = rng.random_range(1..=5);
1957                    buffer.randomly_mutate(&mut rng, edit_count, cx);
1958                    buffer_snapshot = buffer.snapshot(cx);
1959                    let edits = subscription.consume().into_inner();
1960                    log::info!("editing {:?}", edits);
1961                    buffer_edits.extend(edits);
1962                }),
1963            };
1964
1965            let (inlay_snapshot, new_inlay_edits) =
1966                inlay_map.sync(buffer_snapshot.clone(), buffer_edits);
1967            log::info!("inlay text {:?}", inlay_snapshot.text());
1968
1969            let inlay_edits = Patch::new(inlay_edits)
1970                .compose(new_inlay_edits)
1971                .into_inner();
1972            let (snapshot, edits) = map.read(inlay_snapshot.clone(), inlay_edits);
1973            snapshot_edits.push((snapshot.clone(), edits));
1974
1975            let mut expected_text: String = inlay_snapshot.text().to_string();
1976            for fold_range in map.merged_folds().into_iter().rev() {
1977                let fold_inlay_start = inlay_snapshot.to_inlay_offset(fold_range.start);
1978                let fold_inlay_end = inlay_snapshot.to_inlay_offset(fold_range.end);
1979                expected_text.replace_range(fold_inlay_start.0.0..fold_inlay_end.0.0, "");
1980            }
1981
1982            assert_eq!(snapshot.text(), expected_text);
1983            log::info!(
1984                "fold text {:?} ({} lines)",
1985                expected_text,
1986                expected_text.matches('\n').count() + 1
1987            );
1988
1989            let mut prev_row = 0;
1990            let mut expected_buffer_rows = Vec::new();
1991            for fold_range in map.merged_folds() {
1992                let fold_start = inlay_snapshot
1993                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.start))
1994                    .row();
1995                let fold_end = inlay_snapshot
1996                    .to_point(inlay_snapshot.to_inlay_offset(fold_range.end))
1997                    .row();
1998                expected_buffer_rows.extend(
1999                    inlay_snapshot
2000                        .row_infos(prev_row)
2001                        .take((1 + fold_start - prev_row) as usize),
2002                );
2003                prev_row = 1 + fold_end;
2004            }
2005            expected_buffer_rows.extend(inlay_snapshot.row_infos(prev_row));
2006
2007            assert_eq!(
2008                expected_buffer_rows.len(),
2009                expected_text.matches('\n').count() + 1,
2010                "wrong expected buffer rows {:?}. text: {:?}",
2011                expected_buffer_rows,
2012                expected_text
2013            );
2014
2015            for (output_row, line) in expected_text.lines().enumerate() {
2016                let line_len = snapshot.line_len(output_row as u32);
2017                assert_eq!(line_len, line.len() as u32);
2018            }
2019
2020            let longest_row = snapshot.longest_row();
2021            let longest_char_column = expected_text
2022                .split('\n')
2023                .nth(longest_row as usize)
2024                .unwrap()
2025                .chars()
2026                .count();
2027            let mut fold_point = FoldPoint::new(0, 0);
2028            let mut fold_offset = FoldOffset(MultiBufferOffset(0));
2029            let mut char_column = 0;
2030            for c in expected_text.chars() {
2031                let inlay_point = fold_point.to_inlay_point(&snapshot);
2032                let inlay_offset = fold_offset.to_inlay_offset(&snapshot);
2033                assert_eq!(
2034                    snapshot.to_fold_point(inlay_point, Right),
2035                    fold_point,
2036                    "{:?} -> fold point",
2037                    inlay_point,
2038                );
2039                assert_eq!(
2040                    inlay_snapshot.to_offset(inlay_point),
2041                    inlay_offset,
2042                    "inlay_snapshot.to_offset({:?})",
2043                    inlay_point,
2044                );
2045                assert_eq!(
2046                    fold_point.to_offset(&snapshot),
2047                    fold_offset,
2048                    "fold_point.to_offset({:?})",
2049                    fold_point,
2050                );
2051
2052                if c == '\n' {
2053                    *fold_point.row_mut() += 1;
2054                    *fold_point.column_mut() = 0;
2055                    char_column = 0;
2056                } else {
2057                    *fold_point.column_mut() += c.len_utf8() as u32;
2058                    char_column += 1;
2059                }
2060                fold_offset.0 += c.len_utf8();
2061                if char_column > longest_char_column {
2062                    panic!(
2063                        "invalid longest row {:?} (chars {}), found row {:?} (chars: {})",
2064                        longest_row,
2065                        longest_char_column,
2066                        fold_point.row(),
2067                        char_column
2068                    );
2069                }
2070            }
2071
2072            for _ in 0..5 {
2073                let mut start = snapshot.clip_offset(
2074                    FoldOffset(rng.random_range(MultiBufferOffset(0)..=snapshot.len().0)),
2075                    Bias::Left,
2076                );
2077                let mut end = snapshot.clip_offset(
2078                    FoldOffset(rng.random_range(MultiBufferOffset(0)..=snapshot.len().0)),
2079                    Bias::Right,
2080                );
2081                if start > end {
2082                    mem::swap(&mut start, &mut end);
2083                }
2084
2085                let text = &expected_text[start.0.0..end.0.0];
2086                assert_eq!(
2087                    snapshot
2088                        .chunks(start..end, false, Highlights::default())
2089                        .map(|c| c.text)
2090                        .collect::<String>(),
2091                    text,
2092                );
2093            }
2094
2095            let mut fold_row = 0;
2096            while fold_row < expected_buffer_rows.len() as u32 {
2097                assert_eq!(
2098                    snapshot.row_infos(fold_row).collect::<Vec<_>>(),
2099                    expected_buffer_rows[(fold_row as usize)..],
2100                    "wrong buffer rows starting at fold row {}",
2101                    fold_row,
2102                );
2103                fold_row += 1;
2104            }
2105
2106            let folded_buffer_rows = map
2107                .merged_folds()
2108                .iter()
2109                .flat_map(|fold_range| {
2110                    let start_row = fold_range.start.to_point(&buffer_snapshot).row;
2111                    let end = fold_range.end.to_point(&buffer_snapshot);
2112                    if end.column == 0 {
2113                        start_row..end.row
2114                    } else {
2115                        start_row..end.row + 1
2116                    }
2117                })
2118                .collect::<HashSet<_>>();
2119            for row in 0..=buffer_snapshot.max_point().row {
2120                assert_eq!(
2121                    snapshot.is_line_folded(MultiBufferRow(row)),
2122                    folded_buffer_rows.contains(&row),
2123                    "expected buffer row {}{} to be folded",
2124                    row,
2125                    if folded_buffer_rows.contains(&row) {
2126                        ""
2127                    } else {
2128                        " not"
2129                    }
2130                );
2131            }
2132
2133            for _ in 0..5 {
2134                let end = buffer_snapshot.clip_offset(
2135                    rng.random_range(MultiBufferOffset(0)..=buffer_snapshot.len()),
2136                    Right,
2137                );
2138                let start =
2139                    buffer_snapshot.clip_offset(rng.random_range(MultiBufferOffset(0)..=end), Left);
2140                let expected_folds = map
2141                    .snapshot
2142                    .folds
2143                    .items(&buffer_snapshot)
2144                    .into_iter()
2145                    .filter(|fold| {
2146                        let start = buffer_snapshot.anchor_before(start);
2147                        let end = buffer_snapshot.anchor_after(end);
2148                        start.cmp(&fold.range.end, &buffer_snapshot) == Ordering::Less
2149                            && end.cmp(&fold.range.start, &buffer_snapshot) == Ordering::Greater
2150                    })
2151                    .collect::<Vec<_>>();
2152
2153                assert_eq!(
2154                    snapshot
2155                        .folds_in_range(start..end)
2156                        .cloned()
2157                        .collect::<Vec<_>>(),
2158                    expected_folds
2159                );
2160            }
2161
2162            let text = snapshot.text();
2163            for _ in 0..5 {
2164                let start_row = rng.random_range(0..=snapshot.max_point().row());
2165                let start_column = rng.random_range(0..=snapshot.line_len(start_row));
2166                let end_row = rng.random_range(0..=snapshot.max_point().row());
2167                let end_column = rng.random_range(0..=snapshot.line_len(end_row));
2168                let mut start =
2169                    snapshot.clip_point(FoldPoint::new(start_row, start_column), Bias::Left);
2170                let mut end = snapshot.clip_point(FoldPoint::new(end_row, end_column), Bias::Right);
2171                if start > end {
2172                    mem::swap(&mut start, &mut end);
2173                }
2174
2175                let lines = start..end;
2176                let bytes = start.to_offset(&snapshot)..end.to_offset(&snapshot);
2177                assert_eq!(
2178                    snapshot.text_summary_for_range(lines),
2179                    MBTextSummary::from(&text[bytes.start.0.0..bytes.end.0.0])
2180                )
2181            }
2182
2183            let mut text = initial_snapshot.text();
2184            for (snapshot, edits) in snapshot_edits.drain(..) {
2185                let new_text = snapshot.text();
2186                for edit in edits {
2187                    let old_bytes = edit.new.start.0.0..edit.new.start.0.0 + edit.old_len();
2188                    let new_bytes = edit.new.start.0.0..edit.new.end.0.0;
2189                    text.replace_range(old_bytes, &new_text[new_bytes]);
2190                }
2191
2192                assert_eq!(text, new_text);
2193                initial_snapshot = snapshot;
2194            }
2195        }
2196    }
2197
2198    #[gpui::test]
2199    fn test_buffer_rows(cx: &mut gpui::App) {
2200        let text = sample_text(6, 6, 'a') + "\n";
2201        let buffer = MultiBuffer::build_simple(&text, cx);
2202
2203        let buffer_snapshot = buffer.read(cx).snapshot(cx);
2204        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
2205        let mut map = FoldMap::new(inlay_snapshot.clone()).0;
2206
2207        let (mut writer, _, _) = map.write(inlay_snapshot.clone(), vec![]);
2208        writer.fold(vec![
2209            (Point::new(0, 2)..Point::new(2, 2), FoldPlaceholder::test()),
2210            (Point::new(3, 1)..Point::new(4, 1), FoldPlaceholder::test()),
2211        ]);
2212
2213        let (snapshot, _) = map.read(inlay_snapshot, vec![]);
2214        assert_eq!(snapshot.text(), "aa⋯cccc\nd⋯eeeee\nffffff\n");
2215        assert_eq!(
2216            snapshot
2217                .row_infos(0)
2218                .map(|info| info.buffer_row)
2219                .collect::<Vec<_>>(),
2220            [Some(0), Some(3), Some(5), Some(6)]
2221        );
2222        assert_eq!(
2223            snapshot
2224                .row_infos(3)
2225                .map(|info| info.buffer_row)
2226                .collect::<Vec<_>>(),
2227            [Some(6)]
2228        );
2229    }
2230
2231    #[gpui::test(iterations = 100)]
2232    fn test_random_chunk_bitmaps(cx: &mut gpui::App, mut rng: StdRng) {
2233        init_test(cx);
2234
2235        // Generate random buffer using existing test infrastructure
2236        let text_len = rng.random_range(0..10000);
2237        let buffer = if rng.random() {
2238            let text = RandomCharIter::new(&mut rng)
2239                .take(text_len)
2240                .collect::<String>();
2241            MultiBuffer::build_simple(&text, cx)
2242        } else {
2243            MultiBuffer::build_random(&mut rng, cx)
2244        };
2245        let buffer_snapshot = buffer.read(cx).snapshot(cx);
2246        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
2247        let (mut fold_map, _) = FoldMap::new(inlay_snapshot.clone());
2248
2249        // Perform random mutations
2250        let mutation_count = rng.random_range(1..10);
2251        for _ in 0..mutation_count {
2252            fold_map.randomly_mutate(&mut rng);
2253        }
2254
2255        let (snapshot, _) = fold_map.read(inlay_snapshot, vec![]);
2256
2257        // Get all chunks and verify their bitmaps
2258        let chunks = snapshot.chunks(
2259            FoldOffset(MultiBufferOffset(0))..FoldOffset(snapshot.len().0),
2260            false,
2261            Highlights::default(),
2262        );
2263
2264        for chunk in chunks {
2265            let chunk_text = chunk.text;
2266            let chars_bitmap = chunk.chars;
2267            let tabs_bitmap = chunk.tabs;
2268
2269            // Check empty chunks have empty bitmaps
2270            if chunk_text.is_empty() {
2271                assert_eq!(
2272                    chars_bitmap, 0,
2273                    "Empty chunk should have empty chars bitmap"
2274                );
2275                assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
2276                continue;
2277            }
2278
2279            // Verify that chunk text doesn't exceed 128 bytes
2280            assert!(
2281                chunk_text.len() <= 128,
2282                "Chunk text length {} exceeds 128 bytes",
2283                chunk_text.len()
2284            );
2285
2286            // Verify chars bitmap
2287            let char_indices = chunk_text
2288                .char_indices()
2289                .map(|(i, _)| i)
2290                .collect::<Vec<_>>();
2291
2292            for byte_idx in 0..chunk_text.len() {
2293                let should_have_bit = char_indices.contains(&byte_idx);
2294                let has_bit = chars_bitmap & (1 << byte_idx) != 0;
2295
2296                if has_bit != should_have_bit {
2297                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
2298                    eprintln!("Char indices: {:?}", char_indices);
2299                    eprintln!("Chars bitmap: {:#b}", chars_bitmap);
2300                    assert_eq!(
2301                        has_bit, should_have_bit,
2302                        "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
2303                        byte_idx, chunk_text, should_have_bit, has_bit
2304                    );
2305                }
2306            }
2307
2308            // Verify tabs bitmap
2309            for (byte_idx, byte) in chunk_text.bytes().enumerate() {
2310                let is_tab = byte == b'\t';
2311                let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
2312
2313                assert_eq!(
2314                    has_bit, is_tab,
2315                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
2316                    byte_idx, chunk_text, byte as char, is_tab, has_bit
2317                );
2318            }
2319        }
2320    }
2321
2322    fn init_test(cx: &mut gpui::App) {
2323        let store = SettingsStore::test(cx);
2324        cx.set_global(store);
2325    }
2326
2327    impl FoldMap {
2328        fn merged_folds(&self) -> Vec<Range<MultiBufferOffset>> {
2329            let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2330            let buffer = &inlay_snapshot.buffer;
2331            let mut folds = self.snapshot.folds.items(buffer);
2332            // Ensure sorting doesn't change how folds get merged and displayed.
2333            folds.sort_by(|a, b| a.range.cmp(&b.range, buffer));
2334            let mut folds = folds
2335                .iter()
2336                .map(|fold| fold.range.start.to_offset(buffer)..fold.range.end.to_offset(buffer))
2337                .peekable();
2338
2339            let mut merged_folds = Vec::new();
2340            while let Some(mut fold_range) = folds.next() {
2341                while let Some(next_range) = folds.peek() {
2342                    if fold_range.end >= next_range.start {
2343                        if next_range.end > fold_range.end {
2344                            fold_range.end = next_range.end;
2345                        }
2346                        folds.next();
2347                    } else {
2348                        break;
2349                    }
2350                }
2351                if fold_range.end > fold_range.start {
2352                    merged_folds.push(fold_range);
2353                }
2354            }
2355            merged_folds
2356        }
2357
2358        pub fn randomly_mutate(
2359            &mut self,
2360            rng: &mut impl Rng,
2361        ) -> Vec<(FoldSnapshot, Vec<FoldEdit>)> {
2362            let mut snapshot_edits = Vec::new();
2363            match rng.random_range(0..=100) {
2364                0..=39 if !self.snapshot.folds.is_empty() => {
2365                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2366                    let buffer = &inlay_snapshot.buffer;
2367                    let mut to_unfold = Vec::new();
2368                    for _ in 0..rng.random_range(1..=3) {
2369                        let end = buffer.clip_offset(
2370                            rng.random_range(MultiBufferOffset(0)..=buffer.len()),
2371                            Right,
2372                        );
2373                        let start =
2374                            buffer.clip_offset(rng.random_range(MultiBufferOffset(0)..=end), Left);
2375                        to_unfold.push(start..end);
2376                    }
2377                    let inclusive = rng.random();
2378                    log::info!("unfolding {:?} (inclusive: {})", to_unfold, inclusive);
2379                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
2380                    snapshot_edits.push((snapshot, edits));
2381                    let (snapshot, edits) = writer.unfold_intersecting(to_unfold, inclusive);
2382                    snapshot_edits.push((snapshot, edits));
2383                }
2384                _ => {
2385                    let inlay_snapshot = self.snapshot.inlay_snapshot.clone();
2386                    let buffer = &inlay_snapshot.buffer;
2387                    let mut to_fold = Vec::new();
2388                    for _ in 0..rng.random_range(1..=2) {
2389                        let end = buffer.clip_offset(
2390                            rng.random_range(MultiBufferOffset(0)..=buffer.len()),
2391                            Right,
2392                        );
2393                        let start =
2394                            buffer.clip_offset(rng.random_range(MultiBufferOffset(0)..=end), Left);
2395                        to_fold.push((start..end, FoldPlaceholder::test()));
2396                    }
2397                    log::info!("folding {:?}", to_fold);
2398                    let (mut writer, snapshot, edits) = self.write(inlay_snapshot, vec![]);
2399                    snapshot_edits.push((snapshot, edits));
2400                    let (snapshot, edits) = writer.fold(to_fold);
2401                    snapshot_edits.push((snapshot, edits));
2402                }
2403            }
2404            snapshot_edits
2405        }
2406    }
2407}