Skip to content

diff: fallback to longest common substring algorithm #9947

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
yuja wants to merge 3 commits into
base: main
Choose a base branch
from
+319 −122
Open

diff: fallback to longest common substring algorithm #9947

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
75e5368
diff: reject words exceeding max occurrences completely by Histogram
yuja Aug 6, 2026
fd3c846
diff: build histogram (or hash table) by caller of lcs function
yuja Aug 6, 2026
2baa0a4
diff: fallback to longest common substring algorithm
yuja Aug 6, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions CHANGELOG.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
* `jj bisect` will now mention when it cannot unambiguously find the first bad
revision due to skips in evaluation.

* The builtin diff now attempts to split changes into smaller hunks by falling
back to the longest common substring algorithm.

### Fixed bugs

* A side of a conflict whose contents end with a carriage return no longer loses
Expand Down
87 changes: 2 additions & 85 deletions cli/tests/test_diff_command.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1558,89 +1558,6 @@ fn test_diff_color_words_inlining_threshold() {
");
}

#[test]
fn test_diff_color_words_omit_blank_right_line() {
let test_env = TestEnvironment::default();
test_env.run_jj_in(".", ["git", "init", "repo"]).success();
let work_dir = test_env.work_dir("repo");

// The middle hunk of file1 and file3 is
// left = " x\n..."
// right = "\n y\nz "
//
// file2 is different because left/right sides have the same number of "\n".
work_dir.write_file(
"file1",
indoc! {"
a x
b
"},
);
work_dir.write_file(
"file2",
indoc! {"
a x

b
"},
);
work_dir.write_file(
"file3",
indoc! {"
a x


b
"},
);
work_dir.run_jj(["new"]).success();
work_dir.write_file(
"file1",
indoc! {"
a
y
z b
"},
);
work_dir.write_file(
"file2",
indoc! {"
a
y
z b
"},
);
work_dir.write_file(
"file3",
indoc! {"
a
y
z b
"},
);

let output = work_dir
.run_jj(["diff", "--color=always"])
.normalize_stdout_with(strip_ansi_escape_codes);
insta::assert_snapshot!(output, @"
Modified regular file file1:
1 1: a x
2: y
2 3: z b
Modified regular file file2:
1 1: a x
2 2: y
3 3: z b
Modified regular file file3:
1 1: a x
2 :
3 :
2: y
4 3: z b
[EOF]
");
}

#[test]
fn test_diff_missing_newline() {
let test_env = TestEnvironment::default();
Expand Down Expand Up @@ -2950,10 +2867,10 @@ fn test_diff_conflict_bases_differ() {
 7  6: left 3.3
 8 : %%%%%%% diff from: rlvkpnrz 44cfbde6 "base1"
 9 : \\\\\\\ to: royxmykx 3087be1f "right1"
 10 : -line 3
 10 : -line 3
 7: %%%%%%% diff from: vruxwmqv 3c4d67e6 "base2"
 8: \\\\\\\ to: kmkuslsw 656695c3 "right2"
 9: -line 3.1
 9: -line 3.1
 10: -line 3.2
 11  11: +right 3.1
...
Expand Down
Loading
Loading