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sre_engine: resume the tail match at prefix_skip, not past the whole prefix #8473

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Merged
youknowone merged 1 commit into from
Aug 9, 2026
Merged

sre_engine: resume the tail match at prefix_skip, not past the whole prefix #8473

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10 changes: 5 additions & 5 deletions crates/sre_engine/src/engine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -998,12 +998,12 @@ fn search_info_literal<const LITERAL: bool, S: StrDrive>(
return true;
}

// `state.cursor` is `req.start + skip`, the position the
// tail match resumes from; advancing past the prefix
// instead would resume at `req.start + len` and only
// agree when the prefix ends at the skip boundary.
let mut next_ctx = ctx;
if skip != 0 {
next_ctx.advance_char::<S>();
} else {
next_ctx.cursor = state.cursor;
}
next_ctx.cursor = state.cursor;

if _match(req, state, next_ctx) {
return true;
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15 changes: 15 additions & 0 deletions crates/sre_engine/tests/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -252,4 +252,19 @@ mod tests {
#[rustfmt::skip] let p = Pattern { pattern: "\u{e0}+", code: &[14, 4, 0, 1, 4294967295, 24, 6, 1, 4294967295, 16, 224, 1, 1] };
// END GENERATED
}

#[test]
fn search_literal_prefix_longer_than_skip() {
// The INFO block carries prefix_len=4 and prefix_skip=2, so the tail
// match has to resume at the skip boundary rather than past the whole
// prefix.
// pattern p = re.compile('ab(cd)')
// START GENERATED by generate_tests.py
#[rustfmt::skip] let p = Pattern { pattern: "ab(cd)", code: &[14, 14, 1, 4, 4, 4, 2, 97, 98, 99, 100, 0, 0, 0, 0, 16, 97, 16, 98, 17, 0, 16, 99, 16, 100, 17, 1, 1] };
// END GENERATED
let (req, mut state) = p.state("xabcdcd");
assert!(state.search(req));
assert_eq!(state.start, 1);
assert_eq!(state.cursor.position, 5);
}
}
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