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