buffer_diff.rs

   1use futures::channel::oneshot;
   2use git2::{DiffLineType as GitDiffLineType, DiffOptions as GitOptions, Patch as GitPatch};
   3use gpui::{App, AppContext as _, AsyncApp, Context, Entity, EventEmitter, Task};
   4use language::{Language, LanguageRegistry};
   5use rope::Rope;
   6use std::{cmp::Ordering, future::Future, iter, mem, ops::Range, sync::Arc};
   7use sum_tree::SumTree;
   8use text::{Anchor, Bias, BufferId, OffsetRangeExt, Point, ToOffset as _};
   9use util::ResultExt;
  10
  11pub struct BufferDiff {
  12    pub buffer_id: BufferId,
  13    inner: BufferDiffInner,
  14    secondary_diff: Option<Entity<BufferDiff>>,
  15}
  16
  17#[derive(Clone, Debug)]
  18pub struct BufferDiffSnapshot {
  19    inner: BufferDiffInner,
  20    secondary_diff: Option<Box<BufferDiffSnapshot>>,
  21}
  22
  23#[derive(Clone)]
  24struct BufferDiffInner {
  25    hunks: SumTree<InternalDiffHunk>,
  26    pending_hunks: SumTree<PendingHunk>,
  27    base_text: language::BufferSnapshot,
  28    base_text_exists: bool,
  29}
  30
  31#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
  32pub struct DiffHunkStatus {
  33    pub kind: DiffHunkStatusKind,
  34    pub secondary: DiffHunkSecondaryStatus,
  35}
  36
  37#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
  38pub enum DiffHunkStatusKind {
  39    Added,
  40    Modified,
  41    Deleted,
  42}
  43
  44#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
  45pub enum DiffHunkSecondaryStatus {
  46    HasSecondaryHunk,
  47    OverlapsWithSecondaryHunk,
  48    NoSecondaryHunk,
  49    SecondaryHunkAdditionPending,
  50    SecondaryHunkRemovalPending,
  51}
  52
  53/// A diff hunk resolved to rows in the buffer.
  54#[derive(Debug, Clone, PartialEq, Eq)]
  55pub struct DiffHunk {
  56    /// The buffer range as points.
  57    pub range: Range<Point>,
  58    /// The range in the buffer to which this hunk corresponds.
  59    pub buffer_range: Range<Anchor>,
  60    /// The range in the buffer's diff base text to which this hunk corresponds.
  61    pub diff_base_byte_range: Range<usize>,
  62    pub secondary_status: DiffHunkSecondaryStatus,
  63}
  64
  65/// We store [`InternalDiffHunk`]s internally so we don't need to store the additional row range.
  66#[derive(Debug, Clone, PartialEq, Eq)]
  67struct InternalDiffHunk {
  68    buffer_range: Range<Anchor>,
  69    diff_base_byte_range: Range<usize>,
  70}
  71
  72#[derive(Debug, Clone, PartialEq, Eq)]
  73struct PendingHunk {
  74    buffer_range: Range<Anchor>,
  75    diff_base_byte_range: Range<usize>,
  76    buffer_version: clock::Global,
  77    new_status: DiffHunkSecondaryStatus,
  78}
  79
  80#[derive(Debug, Default, Clone)]
  81pub struct DiffHunkSummary {
  82    buffer_range: Range<Anchor>,
  83}
  84
  85impl sum_tree::Item for InternalDiffHunk {
  86    type Summary = DiffHunkSummary;
  87
  88    fn summary(&self, _cx: &text::BufferSnapshot) -> Self::Summary {
  89        DiffHunkSummary {
  90            buffer_range: self.buffer_range.clone(),
  91        }
  92    }
  93}
  94
  95impl sum_tree::Item for PendingHunk {
  96    type Summary = DiffHunkSummary;
  97
  98    fn summary(&self, _cx: &text::BufferSnapshot) -> Self::Summary {
  99        DiffHunkSummary {
 100            buffer_range: self.buffer_range.clone(),
 101        }
 102    }
 103}
 104
 105impl sum_tree::Summary for DiffHunkSummary {
 106    type Context = text::BufferSnapshot;
 107
 108    fn zero(_cx: &Self::Context) -> Self {
 109        Default::default()
 110    }
 111
 112    fn add_summary(&mut self, other: &Self, buffer: &Self::Context) {
 113        self.buffer_range.start = self
 114            .buffer_range
 115            .start
 116            .min(&other.buffer_range.start, buffer);
 117        self.buffer_range.end = self.buffer_range.end.max(&other.buffer_range.end, buffer);
 118    }
 119}
 120
 121impl sum_tree::SeekTarget<'_, DiffHunkSummary, DiffHunkSummary> for Anchor {
 122    fn cmp(&self, cursor_location: &DiffHunkSummary, buffer: &text::BufferSnapshot) -> Ordering {
 123        if self
 124            .cmp(&cursor_location.buffer_range.start, buffer)
 125            .is_lt()
 126        {
 127            Ordering::Less
 128        } else if self.cmp(&cursor_location.buffer_range.end, buffer).is_gt() {
 129            Ordering::Greater
 130        } else {
 131            Ordering::Equal
 132        }
 133    }
 134}
 135
 136impl std::fmt::Debug for BufferDiffInner {
 137    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 138        f.debug_struct("BufferDiffSnapshot")
 139            .field("hunks", &self.hunks)
 140            .finish()
 141    }
 142}
 143
 144impl BufferDiffSnapshot {
 145    pub fn is_empty(&self) -> bool {
 146        self.inner.hunks.is_empty()
 147    }
 148
 149    pub fn secondary_diff(&self) -> Option<&BufferDiffSnapshot> {
 150        self.secondary_diff.as_deref()
 151    }
 152
 153    pub fn hunks_intersecting_range<'a>(
 154        &'a self,
 155        range: Range<Anchor>,
 156        buffer: &'a text::BufferSnapshot,
 157    ) -> impl 'a + Iterator<Item = DiffHunk> {
 158        let unstaged_counterpart = self.secondary_diff.as_ref().map(|diff| &diff.inner);
 159        self.inner
 160            .hunks_intersecting_range(range, buffer, unstaged_counterpart)
 161    }
 162
 163    pub fn hunks_intersecting_range_rev<'a>(
 164        &'a self,
 165        range: Range<Anchor>,
 166        buffer: &'a text::BufferSnapshot,
 167    ) -> impl 'a + Iterator<Item = DiffHunk> {
 168        self.inner.hunks_intersecting_range_rev(range, buffer)
 169    }
 170
 171    pub fn base_text(&self) -> &language::BufferSnapshot {
 172        &self.inner.base_text
 173    }
 174
 175    pub fn base_texts_eq(&self, other: &Self) -> bool {
 176        if self.inner.base_text_exists != other.inner.base_text_exists {
 177            return false;
 178        }
 179        let left = &self.inner.base_text;
 180        let right = &other.inner.base_text;
 181        let (old_id, old_empty) = (left.remote_id(), left.is_empty());
 182        let (new_id, new_empty) = (right.remote_id(), right.is_empty());
 183        new_id == old_id || (new_empty && old_empty)
 184    }
 185}
 186
 187impl BufferDiffInner {
 188    /// Returns the new index text and new pending hunks.
 189    fn stage_or_unstage_hunks_impl(
 190        &mut self,
 191        unstaged_diff: &Self,
 192        stage: bool,
 193        hunks: &[DiffHunk],
 194        buffer: &text::BufferSnapshot,
 195        file_exists: bool,
 196    ) -> Option<Rope> {
 197        let head_text = self
 198            .base_text_exists
 199            .then(|| self.base_text.as_rope().clone());
 200        let index_text = unstaged_diff
 201            .base_text_exists
 202            .then(|| unstaged_diff.base_text.as_rope().clone());
 203
 204        // If the file doesn't exist in either HEAD or the index, then the
 205        // entire file must be either created or deleted in the index.
 206        let (index_text, head_text) = match (index_text, head_text) {
 207            (Some(index_text), Some(head_text)) if file_exists || !stage => (index_text, head_text),
 208            (index_text, head_text) => {
 209                let (new_index_text, new_status) = if stage {
 210                    log::debug!("stage all");
 211                    (
 212                        file_exists.then(|| buffer.as_rope().clone()),
 213                        DiffHunkSecondaryStatus::SecondaryHunkRemovalPending,
 214                    )
 215                } else {
 216                    log::debug!("unstage all");
 217                    (
 218                        head_text,
 219                        DiffHunkSecondaryStatus::SecondaryHunkAdditionPending,
 220                    )
 221                };
 222
 223                let hunk = PendingHunk {
 224                    buffer_range: Anchor::MIN..Anchor::MAX,
 225                    diff_base_byte_range: 0..index_text.map_or(0, |rope| rope.len()),
 226                    buffer_version: buffer.version().clone(),
 227                    new_status,
 228                };
 229                self.pending_hunks = SumTree::from_item(hunk, buffer);
 230                return new_index_text;
 231            }
 232        };
 233
 234        let mut pending_hunks = SumTree::new(buffer);
 235        let mut old_pending_hunks = self.pending_hunks.cursor::<DiffHunkSummary>(buffer);
 236
 237        // first, merge new hunks into pending_hunks
 238        for DiffHunk {
 239            buffer_range,
 240            diff_base_byte_range,
 241            secondary_status,
 242            ..
 243        } in hunks.iter().cloned()
 244        {
 245            let preceding_pending_hunks =
 246                old_pending_hunks.slice(&buffer_range.start, Bias::Left, buffer);
 247            pending_hunks.append(preceding_pending_hunks, buffer);
 248
 249            // Skip all overlapping or adjacent old pending hunks
 250            while old_pending_hunks.item().is_some_and(|old_hunk| {
 251                old_hunk
 252                    .buffer_range
 253                    .start
 254                    .cmp(&buffer_range.end, buffer)
 255                    .is_le()
 256            }) {
 257                old_pending_hunks.next(buffer);
 258            }
 259
 260            if (stage && secondary_status == DiffHunkSecondaryStatus::NoSecondaryHunk)
 261                || (!stage && secondary_status == DiffHunkSecondaryStatus::HasSecondaryHunk)
 262            {
 263                continue;
 264            }
 265
 266            pending_hunks.push(
 267                PendingHunk {
 268                    buffer_range,
 269                    diff_base_byte_range,
 270                    buffer_version: buffer.version().clone(),
 271                    new_status: if stage {
 272                        DiffHunkSecondaryStatus::SecondaryHunkRemovalPending
 273                    } else {
 274                        DiffHunkSecondaryStatus::SecondaryHunkAdditionPending
 275                    },
 276                },
 277                buffer,
 278            );
 279        }
 280        // append the remainder
 281        pending_hunks.append(old_pending_hunks.suffix(buffer), buffer);
 282
 283        let mut unstaged_hunk_cursor = unstaged_diff.hunks.cursor::<DiffHunkSummary>(buffer);
 284        unstaged_hunk_cursor.next(buffer);
 285
 286        // then, iterate over all pending hunks (both new ones and the existing ones) and compute the edits
 287        let mut prev_unstaged_hunk_buffer_end = 0;
 288        let mut prev_unstaged_hunk_base_text_end = 0;
 289        let mut edits = Vec::<(Range<usize>, String)>::new();
 290        let mut pending_hunks_iter = pending_hunks.iter().cloned().peekable();
 291        while let Some(PendingHunk {
 292            buffer_range,
 293            diff_base_byte_range,
 294            ..
 295        }) = pending_hunks_iter.next()
 296        {
 297            // Advance unstaged_hunk_cursor to skip unstaged hunks before current hunk
 298            let skipped_unstaged =
 299                unstaged_hunk_cursor.slice(&buffer_range.start, Bias::Left, buffer);
 300
 301            if let Some(unstaged_hunk) = skipped_unstaged.last() {
 302                prev_unstaged_hunk_base_text_end = unstaged_hunk.diff_base_byte_range.end;
 303                prev_unstaged_hunk_buffer_end = unstaged_hunk.buffer_range.end.to_offset(buffer);
 304            }
 305
 306            // Find where this hunk is in the index if it doesn't overlap
 307            let mut buffer_offset_range = buffer_range.to_offset(buffer);
 308            let start_overshoot = buffer_offset_range.start - prev_unstaged_hunk_buffer_end;
 309            let mut index_start = prev_unstaged_hunk_base_text_end + start_overshoot;
 310
 311            loop {
 312                // Merge this hunk with any overlapping unstaged hunks.
 313                if let Some(unstaged_hunk) = unstaged_hunk_cursor.item() {
 314                    let unstaged_hunk_offset_range = unstaged_hunk.buffer_range.to_offset(buffer);
 315                    if unstaged_hunk_offset_range.start <= buffer_offset_range.end {
 316                        prev_unstaged_hunk_base_text_end = unstaged_hunk.diff_base_byte_range.end;
 317                        prev_unstaged_hunk_buffer_end = unstaged_hunk_offset_range.end;
 318
 319                        index_start = index_start.min(unstaged_hunk.diff_base_byte_range.start);
 320                        buffer_offset_range.start = buffer_offset_range
 321                            .start
 322                            .min(unstaged_hunk_offset_range.start);
 323                        buffer_offset_range.end =
 324                            buffer_offset_range.end.max(unstaged_hunk_offset_range.end);
 325
 326                        unstaged_hunk_cursor.next(buffer);
 327                        continue;
 328                    }
 329                }
 330
 331                // If any unstaged hunks were merged, then subsequent pending hunks may
 332                // now overlap this hunk. Merge them.
 333                if let Some(next_pending_hunk) = pending_hunks_iter.peek() {
 334                    let next_pending_hunk_offset_range =
 335                        next_pending_hunk.buffer_range.to_offset(buffer);
 336                    if next_pending_hunk_offset_range.start <= buffer_offset_range.end {
 337                        buffer_offset_range.end = next_pending_hunk_offset_range.end;
 338                        pending_hunks_iter.next();
 339                        continue;
 340                    }
 341                }
 342
 343                break;
 344            }
 345
 346            let end_overshoot = buffer_offset_range
 347                .end
 348                .saturating_sub(prev_unstaged_hunk_buffer_end);
 349            let index_end = prev_unstaged_hunk_base_text_end + end_overshoot;
 350            let index_byte_range = index_start..index_end;
 351
 352            let replacement_text = if stage {
 353                log::debug!("stage hunk {:?}", buffer_offset_range);
 354                buffer
 355                    .text_for_range(buffer_offset_range)
 356                    .collect::<String>()
 357            } else {
 358                log::debug!("unstage hunk {:?}", buffer_offset_range);
 359                head_text
 360                    .chunks_in_range(diff_base_byte_range.clone())
 361                    .collect::<String>()
 362            };
 363
 364            edits.push((index_byte_range, replacement_text));
 365        }
 366        drop(pending_hunks_iter);
 367        drop(old_pending_hunks);
 368        self.pending_hunks = pending_hunks;
 369
 370        #[cfg(debug_assertions)] // invariants: non-overlapping and sorted
 371        {
 372            for window in edits.windows(2) {
 373                let (range_a, range_b) = (&window[0].0, &window[1].0);
 374                debug_assert!(range_a.end < range_b.start);
 375            }
 376        }
 377
 378        let mut new_index_text = Rope::new();
 379        let mut index_cursor = index_text.cursor(0);
 380
 381        for (old_range, replacement_text) in edits {
 382            new_index_text.append(index_cursor.slice(old_range.start));
 383            index_cursor.seek_forward(old_range.end);
 384            new_index_text.push(&replacement_text);
 385        }
 386        new_index_text.append(index_cursor.suffix());
 387        Some(new_index_text)
 388    }
 389
 390    fn hunks_intersecting_range<'a>(
 391        &'a self,
 392        range: Range<Anchor>,
 393        buffer: &'a text::BufferSnapshot,
 394        secondary: Option<&'a Self>,
 395    ) -> impl 'a + Iterator<Item = DiffHunk> {
 396        let range = range.to_offset(buffer);
 397
 398        let mut cursor = self
 399            .hunks
 400            .filter::<_, DiffHunkSummary>(buffer, move |summary| {
 401                let summary_range = summary.buffer_range.to_offset(buffer);
 402                let before_start = summary_range.end < range.start;
 403                let after_end = summary_range.start > range.end;
 404                !before_start && !after_end
 405            });
 406
 407        let anchor_iter = iter::from_fn(move || {
 408            cursor.next(buffer);
 409            cursor.item()
 410        })
 411        .flat_map(move |hunk| {
 412            [
 413                (
 414                    &hunk.buffer_range.start,
 415                    (hunk.buffer_range.start, hunk.diff_base_byte_range.start),
 416                ),
 417                (
 418                    &hunk.buffer_range.end,
 419                    (hunk.buffer_range.end, hunk.diff_base_byte_range.end),
 420                ),
 421            ]
 422        });
 423
 424        let mut pending_hunks_cursor = self.pending_hunks.cursor::<DiffHunkSummary>(buffer);
 425        pending_hunks_cursor.next(buffer);
 426
 427        let mut secondary_cursor = None;
 428        if let Some(secondary) = secondary.as_ref() {
 429            let mut cursor = secondary.hunks.cursor::<DiffHunkSummary>(buffer);
 430            cursor.next(buffer);
 431            secondary_cursor = Some(cursor);
 432        }
 433
 434        let max_point = buffer.max_point();
 435        let mut summaries = buffer.summaries_for_anchors_with_payload::<Point, _, _>(anchor_iter);
 436        iter::from_fn(move || loop {
 437            let (start_point, (start_anchor, start_base)) = summaries.next()?;
 438            let (mut end_point, (mut end_anchor, end_base)) = summaries.next()?;
 439
 440            if !start_anchor.is_valid(buffer) {
 441                continue;
 442            }
 443
 444            if end_point.column > 0 && end_point < max_point {
 445                end_point.row += 1;
 446                end_point.column = 0;
 447                end_anchor = buffer.anchor_before(end_point);
 448            }
 449
 450            let mut secondary_status = DiffHunkSecondaryStatus::NoSecondaryHunk;
 451
 452            let mut has_pending = false;
 453            if start_anchor
 454                .cmp(&pending_hunks_cursor.start().buffer_range.start, buffer)
 455                .is_gt()
 456            {
 457                pending_hunks_cursor.seek_forward(&start_anchor, Bias::Left, buffer);
 458            }
 459
 460            if let Some(pending_hunk) = pending_hunks_cursor.item() {
 461                let mut pending_range = pending_hunk.buffer_range.to_point(buffer);
 462                if pending_range.end.column > 0 {
 463                    pending_range.end.row += 1;
 464                    pending_range.end.column = 0;
 465                }
 466
 467                if pending_range == (start_point..end_point) {
 468                    if !buffer.has_edits_since_in_range(
 469                        &pending_hunk.buffer_version,
 470                        start_anchor..end_anchor,
 471                    ) {
 472                        has_pending = true;
 473                        secondary_status = pending_hunk.new_status;
 474                    }
 475                }
 476            }
 477
 478            if let (Some(secondary_cursor), false) = (secondary_cursor.as_mut(), has_pending) {
 479                if start_anchor
 480                    .cmp(&secondary_cursor.start().buffer_range.start, buffer)
 481                    .is_gt()
 482                {
 483                    secondary_cursor.seek_forward(&start_anchor, Bias::Left, buffer);
 484                }
 485
 486                if let Some(secondary_hunk) = secondary_cursor.item() {
 487                    let mut secondary_range = secondary_hunk.buffer_range.to_point(buffer);
 488                    if secondary_range.end.column > 0 {
 489                        secondary_range.end.row += 1;
 490                        secondary_range.end.column = 0;
 491                    }
 492                    if secondary_range.is_empty() && secondary_hunk.diff_base_byte_range.is_empty()
 493                    {
 494                        // ignore
 495                    } else if secondary_range == (start_point..end_point) {
 496                        secondary_status = DiffHunkSecondaryStatus::HasSecondaryHunk;
 497                    } else if secondary_range.start <= end_point {
 498                        secondary_status = DiffHunkSecondaryStatus::OverlapsWithSecondaryHunk;
 499                    }
 500                }
 501            }
 502
 503            return Some(DiffHunk {
 504                range: start_point..end_point,
 505                diff_base_byte_range: start_base..end_base,
 506                buffer_range: start_anchor..end_anchor,
 507                secondary_status,
 508            });
 509        })
 510    }
 511
 512    fn hunks_intersecting_range_rev<'a>(
 513        &'a self,
 514        range: Range<Anchor>,
 515        buffer: &'a text::BufferSnapshot,
 516    ) -> impl 'a + Iterator<Item = DiffHunk> {
 517        let mut cursor = self
 518            .hunks
 519            .filter::<_, DiffHunkSummary>(buffer, move |summary| {
 520                let before_start = summary.buffer_range.end.cmp(&range.start, buffer).is_lt();
 521                let after_end = summary.buffer_range.start.cmp(&range.end, buffer).is_gt();
 522                !before_start && !after_end
 523            });
 524
 525        iter::from_fn(move || {
 526            cursor.prev(buffer);
 527
 528            let hunk = cursor.item()?;
 529            let range = hunk.buffer_range.to_point(buffer);
 530
 531            Some(DiffHunk {
 532                range,
 533                diff_base_byte_range: hunk.diff_base_byte_range.clone(),
 534                buffer_range: hunk.buffer_range.clone(),
 535                // The secondary status is not used by callers of this method.
 536                secondary_status: DiffHunkSecondaryStatus::NoSecondaryHunk,
 537            })
 538        })
 539    }
 540
 541    fn compare(&self, old: &Self, new_snapshot: &text::BufferSnapshot) -> Option<Range<Anchor>> {
 542        let mut new_cursor = self.hunks.cursor::<()>(new_snapshot);
 543        let mut old_cursor = old.hunks.cursor::<()>(new_snapshot);
 544        old_cursor.next(new_snapshot);
 545        new_cursor.next(new_snapshot);
 546        let mut start = None;
 547        let mut end = None;
 548
 549        loop {
 550            match (new_cursor.item(), old_cursor.item()) {
 551                (Some(new_hunk), Some(old_hunk)) => {
 552                    match new_hunk
 553                        .buffer_range
 554                        .start
 555                        .cmp(&old_hunk.buffer_range.start, new_snapshot)
 556                    {
 557                        Ordering::Less => {
 558                            start.get_or_insert(new_hunk.buffer_range.start);
 559                            end.replace(new_hunk.buffer_range.end);
 560                            new_cursor.next(new_snapshot);
 561                        }
 562                        Ordering::Equal => {
 563                            if new_hunk != old_hunk {
 564                                start.get_or_insert(new_hunk.buffer_range.start);
 565                                if old_hunk
 566                                    .buffer_range
 567                                    .end
 568                                    .cmp(&new_hunk.buffer_range.end, new_snapshot)
 569                                    .is_ge()
 570                                {
 571                                    end.replace(old_hunk.buffer_range.end);
 572                                } else {
 573                                    end.replace(new_hunk.buffer_range.end);
 574                                }
 575                            }
 576
 577                            new_cursor.next(new_snapshot);
 578                            old_cursor.next(new_snapshot);
 579                        }
 580                        Ordering::Greater => {
 581                            start.get_or_insert(old_hunk.buffer_range.start);
 582                            end.replace(old_hunk.buffer_range.end);
 583                            old_cursor.next(new_snapshot);
 584                        }
 585                    }
 586                }
 587                (Some(new_hunk), None) => {
 588                    start.get_or_insert(new_hunk.buffer_range.start);
 589                    end.replace(new_hunk.buffer_range.end);
 590                    new_cursor.next(new_snapshot);
 591                }
 592                (None, Some(old_hunk)) => {
 593                    start.get_or_insert(old_hunk.buffer_range.start);
 594                    end.replace(old_hunk.buffer_range.end);
 595                    old_cursor.next(new_snapshot);
 596                }
 597                (None, None) => break,
 598            }
 599        }
 600
 601        start.zip(end).map(|(start, end)| start..end)
 602    }
 603}
 604
 605fn compute_hunks(
 606    diff_base: Option<(Arc<String>, Rope)>,
 607    buffer: text::BufferSnapshot,
 608) -> SumTree<InternalDiffHunk> {
 609    let mut tree = SumTree::new(&buffer);
 610
 611    if let Some((diff_base, diff_base_rope)) = diff_base {
 612        let buffer_text = buffer.as_rope().to_string();
 613
 614        let mut options = GitOptions::default();
 615        options.context_lines(0);
 616        let patch = GitPatch::from_buffers(
 617            diff_base.as_bytes(),
 618            None,
 619            buffer_text.as_bytes(),
 620            None,
 621            Some(&mut options),
 622        )
 623        .log_err();
 624
 625        // A common case in Zed is that the empty buffer is represented as just a newline,
 626        // but if we just compute a naive diff you get a "preserved" line in the middle,
 627        // which is a bit odd.
 628        if buffer_text == "\n" && diff_base.ends_with("\n") && diff_base.len() > 1 {
 629            tree.push(
 630                InternalDiffHunk {
 631                    buffer_range: buffer.anchor_before(0)..buffer.anchor_before(0),
 632                    diff_base_byte_range: 0..diff_base.len() - 1,
 633                },
 634                &buffer,
 635            );
 636            return tree;
 637        }
 638
 639        if let Some(patch) = patch {
 640            let mut divergence = 0;
 641            for hunk_index in 0..patch.num_hunks() {
 642                let hunk = process_patch_hunk(
 643                    &patch,
 644                    hunk_index,
 645                    &diff_base_rope,
 646                    &buffer,
 647                    &mut divergence,
 648                );
 649                tree.push(hunk, &buffer);
 650            }
 651        }
 652    } else {
 653        tree.push(
 654            InternalDiffHunk {
 655                buffer_range: Anchor::MIN..Anchor::MAX,
 656                diff_base_byte_range: 0..0,
 657            },
 658            &buffer,
 659        );
 660    }
 661
 662    tree
 663}
 664
 665fn process_patch_hunk(
 666    patch: &GitPatch<'_>,
 667    hunk_index: usize,
 668    diff_base: &Rope,
 669    buffer: &text::BufferSnapshot,
 670    buffer_row_divergence: &mut i64,
 671) -> InternalDiffHunk {
 672    let line_item_count = patch.num_lines_in_hunk(hunk_index).unwrap();
 673    assert!(line_item_count > 0);
 674
 675    let mut first_deletion_buffer_row: Option<u32> = None;
 676    let mut buffer_row_range: Option<Range<u32>> = None;
 677    let mut diff_base_byte_range: Option<Range<usize>> = None;
 678    let mut first_addition_old_row: Option<u32> = None;
 679
 680    for line_index in 0..line_item_count {
 681        let line = patch.line_in_hunk(hunk_index, line_index).unwrap();
 682        let kind = line.origin_value();
 683        let content_offset = line.content_offset() as isize;
 684        let content_len = line.content().len() as isize;
 685        match kind {
 686            GitDiffLineType::Addition => {
 687                if first_addition_old_row.is_none() {
 688                    first_addition_old_row = Some(
 689                        (line.new_lineno().unwrap() as i64 - *buffer_row_divergence - 1) as u32,
 690                    );
 691                }
 692                *buffer_row_divergence += 1;
 693                let row = line.new_lineno().unwrap().saturating_sub(1);
 694
 695                match &mut buffer_row_range {
 696                    Some(Range { end, .. }) => *end = row + 1,
 697                    None => buffer_row_range = Some(row..row + 1),
 698                }
 699            }
 700            GitDiffLineType::Deletion => {
 701                let end = content_offset + content_len;
 702
 703                match &mut diff_base_byte_range {
 704                    Some(head_byte_range) => head_byte_range.end = end as usize,
 705                    None => diff_base_byte_range = Some(content_offset as usize..end as usize),
 706                }
 707
 708                if first_deletion_buffer_row.is_none() {
 709                    let old_row = line.old_lineno().unwrap().saturating_sub(1);
 710                    let row = old_row as i64 + *buffer_row_divergence;
 711                    first_deletion_buffer_row = Some(row as u32);
 712                }
 713
 714                *buffer_row_divergence -= 1;
 715            }
 716            _ => {}
 717        }
 718    }
 719
 720    let buffer_row_range = buffer_row_range.unwrap_or_else(|| {
 721        // Pure deletion hunk without addition.
 722        let row = first_deletion_buffer_row.unwrap();
 723        row..row
 724    });
 725    let diff_base_byte_range = diff_base_byte_range.unwrap_or_else(|| {
 726        // Pure addition hunk without deletion.
 727        let row = first_addition_old_row.unwrap();
 728        let offset = diff_base.point_to_offset(Point::new(row, 0));
 729        offset..offset
 730    });
 731
 732    let start = Point::new(buffer_row_range.start, 0);
 733    let end = Point::new(buffer_row_range.end, 0);
 734    let buffer_range = buffer.anchor_before(start)..buffer.anchor_before(end);
 735    InternalDiffHunk {
 736        buffer_range,
 737        diff_base_byte_range,
 738    }
 739}
 740
 741impl std::fmt::Debug for BufferDiff {
 742    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 743        f.debug_struct("BufferChangeSet")
 744            .field("buffer_id", &self.buffer_id)
 745            .field("snapshot", &self.inner)
 746            .finish()
 747    }
 748}
 749
 750#[derive(Clone, Debug)]
 751pub enum BufferDiffEvent {
 752    DiffChanged {
 753        changed_range: Option<Range<text::Anchor>>,
 754    },
 755    LanguageChanged,
 756    HunksStagedOrUnstaged(Option<Rope>),
 757}
 758
 759impl EventEmitter<BufferDiffEvent> for BufferDiff {}
 760
 761impl BufferDiff {
 762    #[cfg(test)]
 763    fn build_sync(
 764        buffer: text::BufferSnapshot,
 765        diff_base: String,
 766        cx: &mut gpui::TestAppContext,
 767    ) -> BufferDiffInner {
 768        let snapshot =
 769            cx.update(|cx| Self::build(buffer, Some(Arc::new(diff_base)), None, None, cx));
 770        cx.executor().block(snapshot)
 771    }
 772
 773    fn build(
 774        buffer: text::BufferSnapshot,
 775        base_text: Option<Arc<String>>,
 776        language: Option<Arc<Language>>,
 777        language_registry: Option<Arc<LanguageRegistry>>,
 778        cx: &mut App,
 779    ) -> impl Future<Output = BufferDiffInner> {
 780        let base_text_pair;
 781        let base_text_exists;
 782        let base_text_snapshot;
 783        if let Some(text) = &base_text {
 784            let base_text_rope = Rope::from(text.as_str());
 785            base_text_pair = Some((text.clone(), base_text_rope.clone()));
 786            let snapshot = language::Buffer::build_snapshot(
 787                base_text_rope,
 788                language.clone(),
 789                language_registry.clone(),
 790                cx,
 791            );
 792            base_text_snapshot = cx.background_spawn(snapshot);
 793            base_text_exists = true;
 794        } else {
 795            base_text_pair = None;
 796            base_text_snapshot = Task::ready(language::Buffer::build_empty_snapshot(cx));
 797            base_text_exists = false;
 798        };
 799
 800        let hunks = cx.background_spawn({
 801            let buffer = buffer.clone();
 802            async move { compute_hunks(base_text_pair, buffer) }
 803        });
 804
 805        async move {
 806            let (base_text, hunks) = futures::join!(base_text_snapshot, hunks);
 807            BufferDiffInner {
 808                base_text,
 809                hunks,
 810                base_text_exists,
 811                pending_hunks: SumTree::new(&buffer),
 812            }
 813        }
 814    }
 815
 816    fn build_with_base_buffer(
 817        buffer: text::BufferSnapshot,
 818        base_text: Option<Arc<String>>,
 819        base_text_snapshot: language::BufferSnapshot,
 820        cx: &App,
 821    ) -> impl Future<Output = BufferDiffInner> {
 822        let base_text_exists = base_text.is_some();
 823        let base_text_pair = base_text.map(|text| (text, base_text_snapshot.as_rope().clone()));
 824        cx.background_spawn(async move {
 825            BufferDiffInner {
 826                base_text: base_text_snapshot,
 827                pending_hunks: SumTree::new(&buffer),
 828                hunks: compute_hunks(base_text_pair, buffer),
 829                base_text_exists,
 830            }
 831        })
 832    }
 833
 834    fn build_empty(buffer: &text::BufferSnapshot, cx: &mut App) -> BufferDiffInner {
 835        BufferDiffInner {
 836            base_text: language::Buffer::build_empty_snapshot(cx),
 837            hunks: SumTree::new(buffer),
 838            pending_hunks: SumTree::new(buffer),
 839            base_text_exists: false,
 840        }
 841    }
 842
 843    pub fn set_secondary_diff(&mut self, diff: Entity<BufferDiff>) {
 844        self.secondary_diff = Some(diff);
 845    }
 846
 847    pub fn secondary_diff(&self) -> Option<Entity<BufferDiff>> {
 848        self.secondary_diff.clone()
 849    }
 850
 851    pub fn clear_pending_hunks(&mut self, cx: &mut Context<Self>) {
 852        if self.secondary_diff.is_some() {
 853            self.inner.pending_hunks = SumTree::from_summary(DiffHunkSummary::default());
 854            cx.emit(BufferDiffEvent::DiffChanged {
 855                changed_range: Some(Anchor::MIN..Anchor::MAX),
 856            });
 857        }
 858    }
 859
 860    pub fn stage_or_unstage_hunks(
 861        &mut self,
 862        stage: bool,
 863        hunks: &[DiffHunk],
 864        buffer: &text::BufferSnapshot,
 865        file_exists: bool,
 866        cx: &mut Context<Self>,
 867    ) -> Option<Rope> {
 868        let new_index_text = self.inner.stage_or_unstage_hunks_impl(
 869            &self.secondary_diff.as_ref()?.read(cx).inner,
 870            stage,
 871            &hunks,
 872            buffer,
 873            file_exists,
 874        );
 875
 876        cx.emit(BufferDiffEvent::HunksStagedOrUnstaged(
 877            new_index_text.clone(),
 878        ));
 879        if let Some((first, last)) = hunks.first().zip(hunks.last()) {
 880            let changed_range = first.buffer_range.start..last.buffer_range.end;
 881            cx.emit(BufferDiffEvent::DiffChanged {
 882                changed_range: Some(changed_range),
 883            });
 884        }
 885        new_index_text
 886    }
 887
 888    pub fn range_to_hunk_range(
 889        &self,
 890        range: Range<Anchor>,
 891        buffer: &text::BufferSnapshot,
 892        cx: &App,
 893    ) -> Option<Range<Anchor>> {
 894        let start = self
 895            .hunks_intersecting_range(range.clone(), &buffer, cx)
 896            .next()?
 897            .buffer_range
 898            .start;
 899        let end = self
 900            .hunks_intersecting_range_rev(range.clone(), &buffer)
 901            .next()?
 902            .buffer_range
 903            .end;
 904        Some(start..end)
 905    }
 906
 907    pub async fn update_diff(
 908        this: Entity<BufferDiff>,
 909        buffer: text::BufferSnapshot,
 910        base_text: Option<Arc<String>>,
 911        base_text_changed: bool,
 912        language_changed: bool,
 913        language: Option<Arc<Language>>,
 914        language_registry: Option<Arc<LanguageRegistry>>,
 915        cx: &mut AsyncApp,
 916    ) -> anyhow::Result<BufferDiffSnapshot> {
 917        let inner = if base_text_changed || language_changed {
 918            cx.update(|cx| {
 919                Self::build(
 920                    buffer.clone(),
 921                    base_text,
 922                    language.clone(),
 923                    language_registry.clone(),
 924                    cx,
 925                )
 926            })?
 927            .await
 928        } else {
 929            this.read_with(cx, |this, cx| {
 930                Self::build_with_base_buffer(
 931                    buffer.clone(),
 932                    base_text,
 933                    this.base_text().clone(),
 934                    cx,
 935                )
 936            })?
 937            .await
 938        };
 939        Ok(BufferDiffSnapshot {
 940            inner,
 941            secondary_diff: None,
 942        })
 943    }
 944
 945    pub fn set_snapshot(
 946        &mut self,
 947        buffer: &text::BufferSnapshot,
 948        new_snapshot: BufferDiffSnapshot,
 949        language_changed: bool,
 950        secondary_changed_range: Option<Range<Anchor>>,
 951        cx: &mut Context<Self>,
 952    ) -> Option<Range<Anchor>> {
 953        let changed_range = self.set_state(new_snapshot.inner, buffer);
 954        if language_changed {
 955            cx.emit(BufferDiffEvent::LanguageChanged);
 956        }
 957
 958        let changed_range = match (secondary_changed_range, changed_range) {
 959            (None, None) => None,
 960            (Some(unstaged_range), None) => self.range_to_hunk_range(unstaged_range, &buffer, cx),
 961            (None, Some(uncommitted_range)) => Some(uncommitted_range),
 962            (Some(unstaged_range), Some(uncommitted_range)) => {
 963                let mut start = uncommitted_range.start;
 964                let mut end = uncommitted_range.end;
 965                if let Some(unstaged_range) = self.range_to_hunk_range(unstaged_range, &buffer, cx)
 966                {
 967                    start = unstaged_range.start.min(&uncommitted_range.start, &buffer);
 968                    end = unstaged_range.end.max(&uncommitted_range.end, &buffer);
 969                }
 970                Some(start..end)
 971            }
 972        };
 973
 974        cx.emit(BufferDiffEvent::DiffChanged {
 975            changed_range: changed_range.clone(),
 976        });
 977        changed_range
 978    }
 979
 980    fn set_state(
 981        &mut self,
 982        new_state: BufferDiffInner,
 983        buffer: &text::BufferSnapshot,
 984    ) -> Option<Range<Anchor>> {
 985        let (base_text_changed, changed_range) =
 986            match (self.inner.base_text_exists, new_state.base_text_exists) {
 987                (false, false) => (true, None),
 988                (true, true)
 989                    if self.inner.base_text.remote_id() == new_state.base_text.remote_id() =>
 990                {
 991                    (false, new_state.compare(&self.inner, buffer))
 992                }
 993                _ => (true, Some(text::Anchor::MIN..text::Anchor::MAX)),
 994            };
 995
 996        let pending_hunks = mem::replace(&mut self.inner.pending_hunks, SumTree::new(buffer));
 997
 998        self.inner = new_state;
 999        if !base_text_changed {
1000            self.inner.pending_hunks = pending_hunks;
1001        }
1002        changed_range
1003    }
1004
1005    pub fn base_text(&self) -> &language::BufferSnapshot {
1006        &self.inner.base_text
1007    }
1008
1009    pub fn base_text_exists(&self) -> bool {
1010        self.inner.base_text_exists
1011    }
1012
1013    pub fn snapshot(&self, cx: &App) -> BufferDiffSnapshot {
1014        BufferDiffSnapshot {
1015            inner: self.inner.clone(),
1016            secondary_diff: self
1017                .secondary_diff
1018                .as_ref()
1019                .map(|diff| Box::new(diff.read(cx).snapshot(cx))),
1020        }
1021    }
1022
1023    pub fn hunks<'a>(
1024        &'a self,
1025        buffer_snapshot: &'a text::BufferSnapshot,
1026        cx: &'a App,
1027    ) -> impl 'a + Iterator<Item = DiffHunk> {
1028        self.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, buffer_snapshot, cx)
1029    }
1030
1031    pub fn hunks_intersecting_range<'a>(
1032        &'a self,
1033        range: Range<text::Anchor>,
1034        buffer_snapshot: &'a text::BufferSnapshot,
1035        cx: &'a App,
1036    ) -> impl 'a + Iterator<Item = DiffHunk> {
1037        let unstaged_counterpart = self
1038            .secondary_diff
1039            .as_ref()
1040            .map(|diff| &diff.read(cx).inner);
1041        self.inner
1042            .hunks_intersecting_range(range, buffer_snapshot, unstaged_counterpart)
1043    }
1044
1045    pub fn hunks_intersecting_range_rev<'a>(
1046        &'a self,
1047        range: Range<text::Anchor>,
1048        buffer_snapshot: &'a text::BufferSnapshot,
1049    ) -> impl 'a + Iterator<Item = DiffHunk> {
1050        self.inner
1051            .hunks_intersecting_range_rev(range, buffer_snapshot)
1052    }
1053
1054    pub fn hunks_in_row_range<'a>(
1055        &'a self,
1056        range: Range<u32>,
1057        buffer: &'a text::BufferSnapshot,
1058        cx: &'a App,
1059    ) -> impl 'a + Iterator<Item = DiffHunk> {
1060        let start = buffer.anchor_before(Point::new(range.start, 0));
1061        let end = buffer.anchor_after(Point::new(range.end, 0));
1062        self.hunks_intersecting_range(start..end, buffer, cx)
1063    }
1064
1065    /// Used in cases where the change set isn't derived from git.
1066    pub fn set_base_text(
1067        &mut self,
1068        base_buffer: Entity<language::Buffer>,
1069        buffer: text::BufferSnapshot,
1070        cx: &mut Context<Self>,
1071    ) -> oneshot::Receiver<()> {
1072        let (tx, rx) = oneshot::channel();
1073        let this = cx.weak_entity();
1074        let base_buffer = base_buffer.read(cx);
1075        let language_registry = base_buffer.language_registry();
1076        let base_buffer = base_buffer.snapshot();
1077        let base_text = Arc::new(base_buffer.text());
1078
1079        let snapshot = BufferDiff::build(
1080            buffer.clone(),
1081            Some(base_text),
1082            base_buffer.language().cloned(),
1083            language_registry,
1084            cx,
1085        );
1086        let complete_on_drop = util::defer(|| {
1087            tx.send(()).ok();
1088        });
1089        cx.spawn(async move |_, cx| {
1090            let snapshot = snapshot.await;
1091            let Some(this) = this.upgrade() else {
1092                return;
1093            };
1094            this.update(cx, |this, _| {
1095                this.set_state(snapshot, &buffer);
1096            })
1097            .log_err();
1098            drop(complete_on_drop)
1099        })
1100        .detach();
1101        rx
1102    }
1103
1104    pub fn base_text_string(&self) -> Option<String> {
1105        self.inner
1106            .base_text_exists
1107            .then(|| self.inner.base_text.text())
1108    }
1109
1110    pub fn new(buffer: &text::BufferSnapshot, cx: &mut App) -> Self {
1111        BufferDiff {
1112            buffer_id: buffer.remote_id(),
1113            inner: BufferDiff::build_empty(buffer, cx),
1114            secondary_diff: None,
1115        }
1116    }
1117
1118    #[cfg(any(test, feature = "test-support"))]
1119    pub fn new_with_base_text(
1120        base_text: &str,
1121        buffer: &Entity<language::Buffer>,
1122        cx: &mut App,
1123    ) -> Self {
1124        let mut base_text = base_text.to_owned();
1125        text::LineEnding::normalize(&mut base_text);
1126        let snapshot = BufferDiff::build(
1127            buffer.read(cx).text_snapshot(),
1128            Some(base_text.into()),
1129            None,
1130            None,
1131            cx,
1132        );
1133        let snapshot = cx.background_executor().block(snapshot);
1134        BufferDiff {
1135            buffer_id: buffer.read(cx).remote_id(),
1136            inner: snapshot,
1137            secondary_diff: None,
1138        }
1139    }
1140
1141    #[cfg(any(test, feature = "test-support"))]
1142    pub fn recalculate_diff_sync(&mut self, buffer: text::BufferSnapshot, cx: &mut Context<Self>) {
1143        let base_text = self.base_text_string().map(Arc::new);
1144        let snapshot = BufferDiff::build_with_base_buffer(
1145            buffer.clone(),
1146            base_text,
1147            self.inner.base_text.clone(),
1148            cx,
1149        );
1150        let snapshot = cx.background_executor().block(snapshot);
1151        let changed_range = self.set_state(snapshot, &buffer);
1152        cx.emit(BufferDiffEvent::DiffChanged { changed_range });
1153    }
1154}
1155
1156impl DiffHunk {
1157    pub fn is_created_file(&self) -> bool {
1158        self.diff_base_byte_range == (0..0) && self.buffer_range == (Anchor::MIN..Anchor::MAX)
1159    }
1160
1161    pub fn status(&self) -> DiffHunkStatus {
1162        let kind = if self.buffer_range.start == self.buffer_range.end {
1163            DiffHunkStatusKind::Deleted
1164        } else if self.diff_base_byte_range.is_empty() {
1165            DiffHunkStatusKind::Added
1166        } else {
1167            DiffHunkStatusKind::Modified
1168        };
1169        DiffHunkStatus {
1170            kind,
1171            secondary: self.secondary_status,
1172        }
1173    }
1174}
1175
1176impl DiffHunkStatus {
1177    pub fn has_secondary_hunk(&self) -> bool {
1178        matches!(
1179            self.secondary,
1180            DiffHunkSecondaryStatus::HasSecondaryHunk
1181                | DiffHunkSecondaryStatus::SecondaryHunkAdditionPending
1182                | DiffHunkSecondaryStatus::OverlapsWithSecondaryHunk
1183        )
1184    }
1185
1186    pub fn is_pending(&self) -> bool {
1187        matches!(
1188            self.secondary,
1189            DiffHunkSecondaryStatus::SecondaryHunkAdditionPending
1190                | DiffHunkSecondaryStatus::SecondaryHunkRemovalPending
1191        )
1192    }
1193
1194    pub fn is_deleted(&self) -> bool {
1195        self.kind == DiffHunkStatusKind::Deleted
1196    }
1197
1198    pub fn is_added(&self) -> bool {
1199        self.kind == DiffHunkStatusKind::Added
1200    }
1201
1202    pub fn is_modified(&self) -> bool {
1203        self.kind == DiffHunkStatusKind::Modified
1204    }
1205
1206    pub fn added(secondary: DiffHunkSecondaryStatus) -> Self {
1207        Self {
1208            kind: DiffHunkStatusKind::Added,
1209            secondary,
1210        }
1211    }
1212
1213    pub fn modified(secondary: DiffHunkSecondaryStatus) -> Self {
1214        Self {
1215            kind: DiffHunkStatusKind::Modified,
1216            secondary,
1217        }
1218    }
1219
1220    pub fn deleted(secondary: DiffHunkSecondaryStatus) -> Self {
1221        Self {
1222            kind: DiffHunkStatusKind::Deleted,
1223            secondary,
1224        }
1225    }
1226
1227    pub fn deleted_none() -> Self {
1228        Self {
1229            kind: DiffHunkStatusKind::Deleted,
1230            secondary: DiffHunkSecondaryStatus::NoSecondaryHunk,
1231        }
1232    }
1233
1234    pub fn added_none() -> Self {
1235        Self {
1236            kind: DiffHunkStatusKind::Added,
1237            secondary: DiffHunkSecondaryStatus::NoSecondaryHunk,
1238        }
1239    }
1240
1241    pub fn modified_none() -> Self {
1242        Self {
1243            kind: DiffHunkStatusKind::Modified,
1244            secondary: DiffHunkSecondaryStatus::NoSecondaryHunk,
1245        }
1246    }
1247}
1248
1249#[cfg(any(test, feature = "test-support"))]
1250#[track_caller]
1251pub fn assert_hunks<ExpectedText, HunkIter>(
1252    diff_hunks: HunkIter,
1253    buffer: &text::BufferSnapshot,
1254    diff_base: &str,
1255    // Line range, deleted, added, status
1256    expected_hunks: &[(Range<u32>, ExpectedText, ExpectedText, DiffHunkStatus)],
1257) where
1258    HunkIter: Iterator<Item = DiffHunk>,
1259    ExpectedText: AsRef<str>,
1260{
1261    let actual_hunks = diff_hunks
1262        .map(|hunk| {
1263            (
1264                hunk.range.clone(),
1265                &diff_base[hunk.diff_base_byte_range.clone()],
1266                buffer
1267                    .text_for_range(hunk.range.clone())
1268                    .collect::<String>(),
1269                hunk.status(),
1270            )
1271        })
1272        .collect::<Vec<_>>();
1273
1274    let expected_hunks: Vec<_> = expected_hunks
1275        .iter()
1276        .map(|(line_range, deleted_text, added_text, status)| {
1277            (
1278                Point::new(line_range.start, 0)..Point::new(line_range.end, 0),
1279                deleted_text.as_ref(),
1280                added_text.as_ref().to_string(),
1281                *status,
1282            )
1283        })
1284        .collect();
1285
1286    pretty_assertions::assert_eq!(actual_hunks, expected_hunks);
1287}
1288
1289#[cfg(test)]
1290mod tests {
1291    use std::fmt::Write as _;
1292
1293    use super::*;
1294    use gpui::TestAppContext;
1295    use pretty_assertions::{assert_eq, assert_ne};
1296    use rand::{rngs::StdRng, Rng as _};
1297    use text::{Buffer, BufferId, Rope};
1298    use unindent::Unindent as _;
1299    use util::test::marked_text_ranges;
1300
1301    #[ctor::ctor]
1302    fn init_logger() {
1303        if std::env::var("RUST_LOG").is_ok() {
1304            env_logger::init();
1305        }
1306    }
1307
1308    #[gpui::test]
1309    async fn test_buffer_diff_simple(cx: &mut gpui::TestAppContext) {
1310        let diff_base = "
1311            one
1312            two
1313            three
1314        "
1315        .unindent();
1316
1317        let buffer_text = "
1318            one
1319            HELLO
1320            three
1321        "
1322        .unindent();
1323
1324        let mut buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text);
1325        let mut diff = BufferDiff::build_sync(buffer.clone(), diff_base.clone(), cx);
1326        assert_hunks(
1327            diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &buffer, None),
1328            &buffer,
1329            &diff_base,
1330            &[(1..2, "two\n", "HELLO\n", DiffHunkStatus::modified_none())],
1331        );
1332
1333        buffer.edit([(0..0, "point five\n")]);
1334        diff = BufferDiff::build_sync(buffer.clone(), diff_base.clone(), cx);
1335        assert_hunks(
1336            diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &buffer, None),
1337            &buffer,
1338            &diff_base,
1339            &[
1340                (0..1, "", "point five\n", DiffHunkStatus::added_none()),
1341                (2..3, "two\n", "HELLO\n", DiffHunkStatus::modified_none()),
1342            ],
1343        );
1344
1345        diff = cx.update(|cx| BufferDiff::build_empty(&buffer, cx));
1346        assert_hunks::<&str, _>(
1347            diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &buffer, None),
1348            &buffer,
1349            &diff_base,
1350            &[],
1351        );
1352    }
1353
1354    #[gpui::test]
1355    async fn test_buffer_diff_with_secondary(cx: &mut gpui::TestAppContext) {
1356        let head_text = "
1357            zero
1358            one
1359            two
1360            three
1361            four
1362            five
1363            six
1364            seven
1365            eight
1366            nine
1367        "
1368        .unindent();
1369
1370        let index_text = "
1371            zero
1372            one
1373            TWO
1374            three
1375            FOUR
1376            five
1377            six
1378            seven
1379            eight
1380            NINE
1381        "
1382        .unindent();
1383
1384        let buffer_text = "
1385            zero
1386            one
1387            TWO
1388            three
1389            FOUR
1390            FIVE
1391            six
1392            SEVEN
1393            eight
1394            nine
1395        "
1396        .unindent();
1397
1398        let buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text);
1399        let unstaged_diff = BufferDiff::build_sync(buffer.clone(), index_text.clone(), cx);
1400
1401        let uncommitted_diff = BufferDiff::build_sync(buffer.clone(), head_text.clone(), cx);
1402
1403        let expected_hunks = vec![
1404            (2..3, "two\n", "TWO\n", DiffHunkStatus::modified_none()),
1405            (
1406                4..6,
1407                "four\nfive\n",
1408                "FOUR\nFIVE\n",
1409                DiffHunkStatus::modified(DiffHunkSecondaryStatus::OverlapsWithSecondaryHunk),
1410            ),
1411            (
1412                7..8,
1413                "seven\n",
1414                "SEVEN\n",
1415                DiffHunkStatus::modified(DiffHunkSecondaryStatus::HasSecondaryHunk),
1416            ),
1417        ];
1418
1419        assert_hunks(
1420            uncommitted_diff.hunks_intersecting_range(
1421                Anchor::MIN..Anchor::MAX,
1422                &buffer,
1423                Some(&unstaged_diff),
1424            ),
1425            &buffer,
1426            &head_text,
1427            &expected_hunks,
1428        );
1429    }
1430
1431    #[gpui::test]
1432    async fn test_buffer_diff_range(cx: &mut TestAppContext) {
1433        let diff_base = Arc::new(
1434            "
1435            one
1436            two
1437            three
1438            four
1439            five
1440            six
1441            seven
1442            eight
1443            nine
1444            ten
1445        "
1446            .unindent(),
1447        );
1448
1449        let buffer_text = "
1450            A
1451            one
1452            B
1453            two
1454            C
1455            three
1456            HELLO
1457            four
1458            five
1459            SIXTEEN
1460            seven
1461            eight
1462            WORLD
1463            nine
1464
1465            ten
1466
1467        "
1468        .unindent();
1469
1470        let buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text);
1471        let diff = cx
1472            .update(|cx| {
1473                BufferDiff::build(buffer.snapshot(), Some(diff_base.clone()), None, None, cx)
1474            })
1475            .await;
1476        assert_eq!(
1477            diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &buffer, None)
1478                .count(),
1479            8
1480        );
1481
1482        assert_hunks(
1483            diff.hunks_intersecting_range(
1484                buffer.anchor_before(Point::new(7, 0))..buffer.anchor_before(Point::new(12, 0)),
1485                &buffer,
1486                None,
1487            ),
1488            &buffer,
1489            &diff_base,
1490            &[
1491                (6..7, "", "HELLO\n", DiffHunkStatus::added_none()),
1492                (9..10, "six\n", "SIXTEEN\n", DiffHunkStatus::modified_none()),
1493                (12..13, "", "WORLD\n", DiffHunkStatus::added_none()),
1494            ],
1495        );
1496    }
1497
1498    #[gpui::test]
1499    async fn test_stage_hunk(cx: &mut TestAppContext) {
1500        struct Example {
1501            name: &'static str,
1502            head_text: String,
1503            index_text: String,
1504            buffer_marked_text: String,
1505            final_index_text: String,
1506        }
1507
1508        let table = [
1509            Example {
1510                name: "uncommitted hunk straddles end of unstaged hunk",
1511                head_text: "
1512                    one
1513                    two
1514                    three
1515                    four
1516                    five
1517                "
1518                .unindent(),
1519                index_text: "
1520                    one
1521                    TWO_HUNDRED
1522                    three
1523                    FOUR_HUNDRED
1524                    five
1525                "
1526                .unindent(),
1527                buffer_marked_text: "
1528                    ZERO
1529                    one
1530                    two
1531                    «THREE_HUNDRED
1532                    FOUR_HUNDRED»
1533                    five
1534                    SIX
1535                "
1536                .unindent(),
1537                final_index_text: "
1538                    one
1539                    two
1540                    THREE_HUNDRED
1541                    FOUR_HUNDRED
1542                    five
1543                "
1544                .unindent(),
1545            },
1546            Example {
1547                name: "uncommitted hunk straddles start of unstaged hunk",
1548                head_text: "
1549                    one
1550                    two
1551                    three
1552                    four
1553                    five
1554                "
1555                .unindent(),
1556                index_text: "
1557                    one
1558                    TWO_HUNDRED
1559                    three
1560                    FOUR_HUNDRED
1561                    five
1562                "
1563                .unindent(),
1564                buffer_marked_text: "
1565                    ZERO
1566                    one
1567                    «TWO_HUNDRED
1568                    THREE_HUNDRED»
1569                    four
1570                    five
1571                    SIX
1572                "
1573                .unindent(),
1574                final_index_text: "
1575                    one
1576                    TWO_HUNDRED
1577                    THREE_HUNDRED
1578                    four
1579                    five
1580                "
1581                .unindent(),
1582            },
1583            Example {
1584                name: "uncommitted hunk strictly contains unstaged hunks",
1585                head_text: "
1586                    one
1587                    two
1588                    three
1589                    four
1590                    five
1591                    six
1592                    seven
1593                "
1594                .unindent(),
1595                index_text: "
1596                    one
1597                    TWO
1598                    THREE
1599                    FOUR
1600                    FIVE
1601                    SIX
1602                    seven
1603                "
1604                .unindent(),
1605                buffer_marked_text: "
1606                    one
1607                    TWO
1608                    «THREE_HUNDRED
1609                    FOUR
1610                    FIVE_HUNDRED»
1611                    SIX
1612                    seven
1613                "
1614                .unindent(),
1615                final_index_text: "
1616                    one
1617                    TWO
1618                    THREE_HUNDRED
1619                    FOUR
1620                    FIVE_HUNDRED
1621                    SIX
1622                    seven
1623                "
1624                .unindent(),
1625            },
1626            Example {
1627                name: "uncommitted deletion hunk",
1628                head_text: "
1629                    one
1630                    two
1631                    three
1632                    four
1633                    five
1634                "
1635                .unindent(),
1636                index_text: "
1637                    one
1638                    two
1639                    three
1640                    four
1641                    five
1642                "
1643                .unindent(),
1644                buffer_marked_text: "
1645                    one
1646                    ˇfive
1647                "
1648                .unindent(),
1649                final_index_text: "
1650                    one
1651                    five
1652                "
1653                .unindent(),
1654            },
1655            Example {
1656                name: "one unstaged hunk that contains two uncommitted hunks",
1657                head_text: "
1658                    one
1659                    two
1660
1661                    three
1662                    four
1663                "
1664                .unindent(),
1665                index_text: "
1666                    one
1667                    two
1668                    three
1669                    four
1670                "
1671                .unindent(),
1672                buffer_marked_text: "
1673                    «one
1674
1675                    three // modified
1676                    four»
1677                "
1678                .unindent(),
1679                final_index_text: "
1680                    one
1681
1682                    three // modified
1683                    four
1684                "
1685                .unindent(),
1686            },
1687            Example {
1688                name: "one uncommitted hunk that contains two unstaged hunks",
1689                head_text: "
1690                    one
1691                    two
1692                    three
1693                    four
1694                    five
1695                "
1696                .unindent(),
1697                index_text: "
1698                    ZERO
1699                    one
1700                    TWO
1701                    THREE
1702                    FOUR
1703                    five
1704                "
1705                .unindent(),
1706                buffer_marked_text: "
1707                    «one
1708                    TWO_HUNDRED
1709                    THREE
1710                    FOUR_HUNDRED
1711                    five»
1712                "
1713                .unindent(),
1714                final_index_text: "
1715                    ZERO
1716                    one
1717                    TWO_HUNDRED
1718                    THREE
1719                    FOUR_HUNDRED
1720                    five
1721                "
1722                .unindent(),
1723            },
1724        ];
1725
1726        for example in table {
1727            let (buffer_text, ranges) = marked_text_ranges(&example.buffer_marked_text, false);
1728            let buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text);
1729            let hunk_range =
1730                buffer.anchor_before(ranges[0].start)..buffer.anchor_before(ranges[0].end);
1731
1732            let unstaged = BufferDiff::build_sync(buffer.clone(), example.index_text.clone(), cx);
1733            let uncommitted = BufferDiff::build_sync(buffer.clone(), example.head_text.clone(), cx);
1734
1735            let unstaged_diff = cx.new(|cx| {
1736                let mut diff = BufferDiff::new(&buffer, cx);
1737                diff.set_state(unstaged, &buffer);
1738                diff
1739            });
1740
1741            let uncommitted_diff = cx.new(|cx| {
1742                let mut diff = BufferDiff::new(&buffer, cx);
1743                diff.set_state(uncommitted, &buffer);
1744                diff.set_secondary_diff(unstaged_diff);
1745                diff
1746            });
1747
1748            uncommitted_diff.update(cx, |diff, cx| {
1749                let hunks = diff
1750                    .hunks_intersecting_range(hunk_range.clone(), &buffer, &cx)
1751                    .collect::<Vec<_>>();
1752                for hunk in &hunks {
1753                    assert_ne!(
1754                        hunk.secondary_status,
1755                        DiffHunkSecondaryStatus::NoSecondaryHunk
1756                    )
1757                }
1758
1759                let new_index_text = diff
1760                    .stage_or_unstage_hunks(true, &hunks, &buffer, true, cx)
1761                    .unwrap()
1762                    .to_string();
1763
1764                let hunks = diff
1765                    .hunks_intersecting_range(hunk_range.clone(), &buffer, &cx)
1766                    .collect::<Vec<_>>();
1767                for hunk in &hunks {
1768                    assert_eq!(
1769                        hunk.secondary_status,
1770                        DiffHunkSecondaryStatus::SecondaryHunkRemovalPending
1771                    )
1772                }
1773
1774                pretty_assertions::assert_eq!(
1775                    new_index_text,
1776                    example.final_index_text,
1777                    "example: {}",
1778                    example.name
1779                );
1780            });
1781        }
1782    }
1783
1784    #[gpui::test]
1785    async fn test_toggling_stage_and_unstage_same_hunk(cx: &mut TestAppContext) {
1786        let head_text = "
1787            one
1788            two
1789            three
1790        "
1791        .unindent();
1792        let index_text = head_text.clone();
1793        let buffer_text = "
1794            one
1795            three
1796        "
1797        .unindent();
1798
1799        let buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text.clone());
1800        let unstaged = BufferDiff::build_sync(buffer.clone(), index_text, cx);
1801        let uncommitted = BufferDiff::build_sync(buffer.clone(), head_text.clone(), cx);
1802        let unstaged_diff = cx.new(|cx| {
1803            let mut diff = BufferDiff::new(&buffer, cx);
1804            diff.set_state(unstaged, &buffer);
1805            diff
1806        });
1807        let uncommitted_diff = cx.new(|cx| {
1808            let mut diff = BufferDiff::new(&buffer, cx);
1809            diff.set_state(uncommitted, &buffer);
1810            diff.set_secondary_diff(unstaged_diff.clone());
1811            diff
1812        });
1813
1814        uncommitted_diff.update(cx, |diff, cx| {
1815            let hunk = diff.hunks(&buffer, cx).next().unwrap();
1816
1817            let new_index_text = diff
1818                .stage_or_unstage_hunks(true, &[hunk.clone()], &buffer, true, cx)
1819                .unwrap()
1820                .to_string();
1821            assert_eq!(new_index_text, buffer_text);
1822
1823            let hunk = diff.hunks(&buffer, &cx).next().unwrap();
1824            assert_eq!(
1825                hunk.secondary_status,
1826                DiffHunkSecondaryStatus::SecondaryHunkRemovalPending
1827            );
1828
1829            let index_text = diff
1830                .stage_or_unstage_hunks(false, &[hunk], &buffer, true, cx)
1831                .unwrap()
1832                .to_string();
1833            assert_eq!(index_text, head_text);
1834
1835            let hunk = diff.hunks(&buffer, &cx).next().unwrap();
1836            // optimistically unstaged (fine, could also be HasSecondaryHunk)
1837            assert_eq!(
1838                hunk.secondary_status,
1839                DiffHunkSecondaryStatus::SecondaryHunkAdditionPending
1840            );
1841        });
1842    }
1843
1844    #[gpui::test]
1845    async fn test_buffer_diff_compare(cx: &mut TestAppContext) {
1846        let base_text = "
1847            zero
1848            one
1849            two
1850            three
1851            four
1852            five
1853            six
1854            seven
1855            eight
1856            nine
1857        "
1858        .unindent();
1859
1860        let buffer_text_1 = "
1861            one
1862            three
1863            four
1864            five
1865            SIX
1866            seven
1867            eight
1868            NINE
1869        "
1870        .unindent();
1871
1872        let mut buffer = Buffer::new(0, BufferId::new(1).unwrap(), buffer_text_1);
1873
1874        let empty_diff = cx.update(|cx| BufferDiff::build_empty(&buffer, cx));
1875        let diff_1 = BufferDiff::build_sync(buffer.clone(), base_text.clone(), cx);
1876        let range = diff_1.compare(&empty_diff, &buffer).unwrap();
1877        assert_eq!(range.to_point(&buffer), Point::new(0, 0)..Point::new(8, 0));
1878
1879        // Edit does not affect the diff.
1880        buffer.edit_via_marked_text(
1881            &"
1882                one
1883                three
1884                four
1885                five
1886                «SIX.5»
1887                seven
1888                eight
1889                NINE
1890            "
1891            .unindent(),
1892        );
1893        let diff_2 = BufferDiff::build_sync(buffer.clone(), base_text.clone(), cx);
1894        assert_eq!(None, diff_2.compare(&diff_1, &buffer));
1895
1896        // Edit turns a deletion hunk into a modification.
1897        buffer.edit_via_marked_text(
1898            &"
1899                one
1900                «THREE»
1901                four
1902                five
1903                SIX.5
1904                seven
1905                eight
1906                NINE
1907            "
1908            .unindent(),
1909        );
1910        let diff_3 = BufferDiff::build_sync(buffer.clone(), base_text.clone(), cx);
1911        let range = diff_3.compare(&diff_2, &buffer).unwrap();
1912        assert_eq!(range.to_point(&buffer), Point::new(1, 0)..Point::new(2, 0));
1913
1914        // Edit turns a modification hunk into a deletion.
1915        buffer.edit_via_marked_text(
1916            &"
1917                one
1918                THREE
1919                four
1920                five«»
1921                seven
1922                eight
1923                NINE
1924            "
1925            .unindent(),
1926        );
1927        let diff_4 = BufferDiff::build_sync(buffer.clone(), base_text.clone(), cx);
1928        let range = diff_4.compare(&diff_3, &buffer).unwrap();
1929        assert_eq!(range.to_point(&buffer), Point::new(3, 4)..Point::new(4, 0));
1930
1931        // Edit introduces a new insertion hunk.
1932        buffer.edit_via_marked_text(
1933            &"
1934                one
1935                THREE
1936                four«
1937                FOUR.5
1938                »five
1939                seven
1940                eight
1941                NINE
1942            "
1943            .unindent(),
1944        );
1945        let diff_5 = BufferDiff::build_sync(buffer.snapshot(), base_text.clone(), cx);
1946        let range = diff_5.compare(&diff_4, &buffer).unwrap();
1947        assert_eq!(range.to_point(&buffer), Point::new(3, 0)..Point::new(4, 0));
1948
1949        // Edit removes a hunk.
1950        buffer.edit_via_marked_text(
1951            &"
1952                one
1953                THREE
1954                four
1955                FOUR.5
1956                five
1957                seven
1958                eight
1959                «nine»
1960            "
1961            .unindent(),
1962        );
1963        let diff_6 = BufferDiff::build_sync(buffer.snapshot(), base_text, cx);
1964        let range = diff_6.compare(&diff_5, &buffer).unwrap();
1965        assert_eq!(range.to_point(&buffer), Point::new(7, 0)..Point::new(8, 0));
1966    }
1967
1968    #[gpui::test(iterations = 100)]
1969    async fn test_staging_and_unstaging_hunks(cx: &mut TestAppContext, mut rng: StdRng) {
1970        fn gen_line(rng: &mut StdRng) -> String {
1971            if rng.gen_bool(0.2) {
1972                "\n".to_owned()
1973            } else {
1974                let c = rng.gen_range('A'..='Z');
1975                format!("{c}{c}{c}\n")
1976            }
1977        }
1978
1979        fn gen_working_copy(rng: &mut StdRng, head: &str) -> String {
1980            let mut old_lines = {
1981                let mut old_lines = Vec::new();
1982                let mut old_lines_iter = head.lines();
1983                while let Some(line) = old_lines_iter.next() {
1984                    assert!(!line.ends_with("\n"));
1985                    old_lines.push(line.to_owned());
1986                }
1987                if old_lines.last().is_some_and(|line| line.is_empty()) {
1988                    old_lines.pop();
1989                }
1990                old_lines.into_iter()
1991            };
1992            let mut result = String::new();
1993            let unchanged_count = rng.gen_range(0..=old_lines.len());
1994            result +=
1995                &old_lines
1996                    .by_ref()
1997                    .take(unchanged_count)
1998                    .fold(String::new(), |mut s, line| {
1999                        writeln!(&mut s, "{line}").unwrap();
2000                        s
2001                    });
2002            while old_lines.len() > 0 {
2003                let deleted_count = rng.gen_range(0..=old_lines.len());
2004                let _advance = old_lines
2005                    .by_ref()
2006                    .take(deleted_count)
2007                    .map(|line| line.len() + 1)
2008                    .sum::<usize>();
2009                let minimum_added = if deleted_count == 0 { 1 } else { 0 };
2010                let added_count = rng.gen_range(minimum_added..=5);
2011                let addition = (0..added_count).map(|_| gen_line(rng)).collect::<String>();
2012                result += &addition;
2013
2014                if old_lines.len() > 0 {
2015                    let blank_lines = old_lines.clone().take_while(|line| line.is_empty()).count();
2016                    if blank_lines == old_lines.len() {
2017                        break;
2018                    };
2019                    let unchanged_count = rng.gen_range((blank_lines + 1).max(1)..=old_lines.len());
2020                    result += &old_lines.by_ref().take(unchanged_count).fold(
2021                        String::new(),
2022                        |mut s, line| {
2023                            writeln!(&mut s, "{line}").unwrap();
2024                            s
2025                        },
2026                    );
2027                }
2028            }
2029            result
2030        }
2031
2032        fn uncommitted_diff(
2033            working_copy: &language::BufferSnapshot,
2034            index_text: &Rope,
2035            head_text: String,
2036            cx: &mut TestAppContext,
2037        ) -> Entity<BufferDiff> {
2038            let inner = BufferDiff::build_sync(working_copy.text.clone(), head_text, cx);
2039            let secondary = BufferDiff {
2040                buffer_id: working_copy.remote_id(),
2041                inner: BufferDiff::build_sync(
2042                    working_copy.text.clone(),
2043                    index_text.to_string(),
2044                    cx,
2045                ),
2046                secondary_diff: None,
2047            };
2048            let secondary = cx.new(|_| secondary);
2049            cx.new(|_| BufferDiff {
2050                buffer_id: working_copy.remote_id(),
2051                inner,
2052                secondary_diff: Some(secondary),
2053            })
2054        }
2055
2056        let operations = std::env::var("OPERATIONS")
2057            .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
2058            .unwrap_or(10);
2059
2060        let rng = &mut rng;
2061        let head_text = ('a'..='z').fold(String::new(), |mut s, c| {
2062            writeln!(&mut s, "{c}{c}{c}").unwrap();
2063            s
2064        });
2065        let working_copy = gen_working_copy(rng, &head_text);
2066        let working_copy = cx.new(|cx| {
2067            language::Buffer::local_normalized(
2068                Rope::from(working_copy.as_str()),
2069                text::LineEnding::default(),
2070                cx,
2071            )
2072        });
2073        let working_copy = working_copy.read_with(cx, |working_copy, _| working_copy.snapshot());
2074        let mut index_text = if rng.gen() {
2075            Rope::from(head_text.as_str())
2076        } else {
2077            working_copy.as_rope().clone()
2078        };
2079
2080        let mut diff = uncommitted_diff(&working_copy, &index_text, head_text.clone(), cx);
2081        let mut hunks = diff.update(cx, |diff, cx| {
2082            diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &working_copy, cx)
2083                .collect::<Vec<_>>()
2084        });
2085        if hunks.len() == 0 {
2086            return;
2087        }
2088
2089        for _ in 0..operations {
2090            let i = rng.gen_range(0..hunks.len());
2091            let hunk = &mut hunks[i];
2092            let hunk_to_change = hunk.clone();
2093            let stage = match hunk.secondary_status {
2094                DiffHunkSecondaryStatus::HasSecondaryHunk => {
2095                    hunk.secondary_status = DiffHunkSecondaryStatus::NoSecondaryHunk;
2096                    true
2097                }
2098                DiffHunkSecondaryStatus::NoSecondaryHunk => {
2099                    hunk.secondary_status = DiffHunkSecondaryStatus::HasSecondaryHunk;
2100                    false
2101                }
2102                _ => unreachable!(),
2103            };
2104
2105            index_text = diff.update(cx, |diff, cx| {
2106                diff.stage_or_unstage_hunks(stage, &[hunk_to_change], &working_copy, true, cx)
2107                    .unwrap()
2108            });
2109
2110            diff = uncommitted_diff(&working_copy, &index_text, head_text.clone(), cx);
2111            let found_hunks = diff.update(cx, |diff, cx| {
2112                diff.hunks_intersecting_range(Anchor::MIN..Anchor::MAX, &working_copy, cx)
2113                    .collect::<Vec<_>>()
2114            });
2115            assert_eq!(hunks.len(), found_hunks.len());
2116
2117            for (expected_hunk, found_hunk) in hunks.iter().zip(&found_hunks) {
2118                assert_eq!(
2119                    expected_hunk.buffer_range.to_point(&working_copy),
2120                    found_hunk.buffer_range.to_point(&working_copy)
2121                );
2122                assert_eq!(
2123                    expected_hunk.diff_base_byte_range,
2124                    found_hunk.diff_base_byte_range
2125                );
2126                assert_eq!(expected_hunk.secondary_status, found_hunk.secondary_status);
2127            }
2128            hunks = found_hunks;
2129        }
2130    }
2131}