1use std::ops::Range;
2
3use sum_tree::SumTree;
4use text::{Anchor, BufferSnapshot, OffsetRangeExt, Point, ToPoint};
5
6pub use git2 as libgit;
7use libgit::{DiffLineType as GitDiffLineType, DiffOptions as GitOptions, Patch as GitPatch};
8
9#[derive(Debug, Clone, Copy)]
10pub enum DiffHunkStatus {
11 Added,
12 Modified,
13 Removed,
14}
15
16#[derive(Debug, Clone, PartialEq, Eq)]
17pub struct DiffHunk<T> {
18 pub buffer_range: Range<T>,
19 pub head_byte_range: Range<usize>,
20}
21
22impl DiffHunk<u32> {
23 pub fn status(&self) -> DiffHunkStatus {
24 if self.head_byte_range.is_empty() {
25 DiffHunkStatus::Added
26 } else if self.buffer_range.is_empty() {
27 DiffHunkStatus::Removed
28 } else {
29 DiffHunkStatus::Modified
30 }
31 }
32}
33
34impl sum_tree::Item for DiffHunk<Anchor> {
35 type Summary = DiffHunkSummary;
36
37 fn summary(&self) -> Self::Summary {
38 DiffHunkSummary {
39 buffer_range: self.buffer_range.clone(),
40 head_range: self.head_byte_range.clone(),
41 }
42 }
43}
44
45#[derive(Debug, Default, Clone)]
46pub struct DiffHunkSummary {
47 buffer_range: Range<Anchor>,
48 head_range: Range<usize>,
49}
50
51impl sum_tree::Summary for DiffHunkSummary {
52 type Context = text::BufferSnapshot;
53
54 fn add_summary(&mut self, other: &Self, _: &Self::Context) {
55 self.head_range.start = self.head_range.start.min(other.head_range.start);
56 self.head_range.end = self.head_range.end.max(other.head_range.end);
57 }
58}
59
60#[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord)]
61struct HunkHeadEnd(usize);
62
63impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkHeadEnd {
64 fn add_summary(&mut self, summary: &'a DiffHunkSummary, _: &text::BufferSnapshot) {
65 self.0 = summary.head_range.end;
66 }
67
68 fn from_summary(summary: &'a DiffHunkSummary, _: &text::BufferSnapshot) -> Self {
69 HunkHeadEnd(summary.head_range.end)
70 }
71}
72
73#[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord)]
74struct HunkBufferStart(u32);
75
76impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkBufferStart {
77 fn add_summary(&mut self, summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) {
78 self.0 = summary.buffer_range.start.to_point(buffer).row;
79 }
80
81 fn from_summary(summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) -> Self {
82 HunkBufferStart(summary.buffer_range.start.to_point(buffer).row)
83 }
84}
85
86#[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord)]
87struct HunkBufferEnd(u32);
88
89impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkBufferEnd {
90 fn add_summary(&mut self, summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) {
91 self.0 = summary.buffer_range.end.to_point(buffer).row;
92 }
93
94 fn from_summary(summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) -> Self {
95 HunkBufferEnd(summary.buffer_range.end.to_point(buffer).row)
96 }
97}
98
99#[derive(Clone)]
100pub struct BufferDiff {
101 last_buffer_version: Option<clock::Global>,
102 tree: SumTree<DiffHunk<Anchor>>,
103}
104
105impl BufferDiff {
106 pub fn new() -> BufferDiff {
107 BufferDiff {
108 last_buffer_version: None,
109 tree: SumTree::new(),
110 }
111 }
112
113 pub fn hunks_in_range<'a>(
114 &'a self,
115 query_row_range: Range<u32>,
116 buffer: &'a BufferSnapshot,
117 ) -> impl 'a + Iterator<Item = DiffHunk<u32>> {
118 self.tree.iter().filter_map(move |hunk| {
119 let range = hunk.buffer_range.to_point(&buffer);
120
121 if range.start.row <= query_row_range.end && query_row_range.start <= range.end.row {
122 let end_row = if range.end.column > 0 {
123 range.end.row + 1
124 } else {
125 range.end.row
126 };
127
128 Some(DiffHunk {
129 buffer_range: range.start.row..end_row,
130 head_byte_range: hunk.head_byte_range.clone(),
131 })
132 } else {
133 None
134 }
135 })
136 }
137
138 pub fn needs_update(&self, buffer: &text::BufferSnapshot) -> bool {
139 match &self.last_buffer_version {
140 Some(last) => buffer.version().changed_since(last),
141 None => true,
142 }
143 }
144
145 pub async fn update(&mut self, head_text: &str, buffer: &text::BufferSnapshot) {
146 let mut tree = SumTree::new();
147
148 let buffer_text = buffer.as_rope().to_string();
149 let patch = Self::diff(&head_text, &buffer_text);
150
151 if let Some(patch) = patch {
152 let mut divergence = 0;
153 for hunk_index in 0..patch.num_hunks() {
154 let hunk = Self::process_patch_hunk(&patch, hunk_index, buffer, &mut divergence);
155 tree.push(hunk, buffer);
156 }
157 }
158
159 self.tree = tree;
160 self.last_buffer_version = Some(buffer.version().clone());
161 }
162
163 #[cfg(test)]
164 fn hunks<'a>(&'a self, text: &'a BufferSnapshot) -> impl 'a + Iterator<Item = DiffHunk<u32>> {
165 self.hunks_in_range(0..u32::MAX, text)
166 }
167
168 fn diff<'a>(head: &'a str, current: &'a str) -> Option<GitPatch<'a>> {
169 let mut options = GitOptions::default();
170 options.context_lines(0);
171
172 let patch = GitPatch::from_buffers(
173 head.as_bytes(),
174 None,
175 current.as_bytes(),
176 None,
177 Some(&mut options),
178 );
179
180 match patch {
181 Ok(patch) => Some(patch),
182
183 Err(err) => {
184 log::error!("`GitPatch::from_buffers` failed: {}", err);
185 None
186 }
187 }
188 }
189
190 fn process_patch_hunk<'a>(
191 patch: &GitPatch<'a>,
192 hunk_index: usize,
193 buffer: &text::BufferSnapshot,
194 buffer_row_divergence: &mut i64,
195 ) -> DiffHunk<Anchor> {
196 let line_item_count = patch.num_lines_in_hunk(hunk_index).unwrap();
197 assert!(line_item_count > 0);
198
199 let mut first_deletion_buffer_row: Option<u32> = None;
200 let mut buffer_row_range: Option<Range<u32>> = None;
201 let mut head_byte_range: Option<Range<usize>> = None;
202
203 for line_index in 0..line_item_count {
204 let line = patch.line_in_hunk(hunk_index, line_index).unwrap();
205 let kind = line.origin_value();
206 let content_offset = line.content_offset() as isize;
207 let content_len = line.content().len() as isize;
208
209 if kind == GitDiffLineType::Addition {
210 *buffer_row_divergence += 1;
211 let row = line.new_lineno().unwrap().saturating_sub(1);
212
213 match &mut buffer_row_range {
214 Some(buffer_row_range) => buffer_row_range.end = row + 1,
215 None => buffer_row_range = Some(row..row + 1),
216 }
217 }
218
219 if kind == GitDiffLineType::Deletion {
220 *buffer_row_divergence -= 1;
221 let end = content_offset + content_len;
222
223 match &mut head_byte_range {
224 Some(head_byte_range) => head_byte_range.end = end as usize,
225 None => head_byte_range = Some(content_offset as usize..end as usize),
226 }
227
228 if first_deletion_buffer_row.is_none() {
229 let old_row = line.old_lineno().unwrap().saturating_sub(1);
230 let row = old_row as i64 + *buffer_row_divergence;
231 first_deletion_buffer_row = Some(row as u32);
232 }
233 }
234 }
235
236 //unwrap_or deletion without addition
237 let buffer_row_range = buffer_row_range.unwrap_or_else(|| {
238 //we cannot have an addition-less hunk without deletion(s) or else there would be no hunk
239 let row = first_deletion_buffer_row.unwrap();
240 row..row
241 });
242
243 //unwrap_or addition without deletion
244 let head_byte_range = head_byte_range.unwrap_or(0..0);
245
246 let start = Point::new(buffer_row_range.start, 0);
247 let end = Point::new(buffer_row_range.end, 0);
248 let buffer_range = buffer.anchor_before(start)..buffer.anchor_before(end);
249 DiffHunk {
250 buffer_range,
251 head_byte_range,
252 }
253 }
254}
255
256#[cfg(test)]
257mod tests {
258 use super::*;
259 use text::Buffer;
260 use unindent::Unindent as _;
261
262 #[gpui::test]
263 fn test_buffer_diff_simple() {
264 let head_text = "
265 one
266 two
267 three
268 "
269 .unindent();
270
271 let buffer_text = "
272 one
273 hello
274 three
275 "
276 .unindent();
277
278 let mut buffer = Buffer::new(0, 0, buffer_text);
279 let mut diff = BufferDiff::new();
280 smol::block_on(diff.update(&head_text, &buffer));
281 assert_hunks(&diff, &buffer, &head_text, &[(1..2, "two\n")]);
282
283 buffer.edit([(0..0, "point five\n")]);
284 assert_hunks(&diff, &buffer, &head_text, &[(2..3, "two\n")]);
285 }
286
287 #[track_caller]
288 fn assert_hunks(
289 diff: &BufferDiff,
290 buffer: &BufferSnapshot,
291 head_text: &str,
292 expected_hunks: &[(Range<u32>, &str)],
293 ) {
294 let hunks = diff.hunks(buffer).collect::<Vec<_>>();
295 assert_eq!(
296 hunks.len(),
297 expected_hunks.len(),
298 "actual hunks are {hunks:#?}"
299 );
300
301 let diff_iter = hunks.iter().enumerate();
302 for ((index, hunk), (expected_range, expected_str)) in diff_iter.zip(expected_hunks) {
303 assert_eq!(&hunk.buffer_range, expected_range, "for hunk {index}");
304 assert_eq!(
305 &head_text[hunk.head_byte_range.clone()],
306 *expected_str,
307 "for hunk {index}"
308 );
309 }
310 }
311
312 // use rand::rngs::StdRng;
313 // #[gpui::test(iterations = 100)]
314 // fn test_buffer_diff_random(mut rng: StdRng) {}
315}