Shannon Booth ba59640ab2 LibRegex: Avoid hitting backtrack limit for bounded grouped repetitions ...

Unrolling a bounded quantifier {min,max} into (max-min) optional Split
chains lets the backtracker explore O(2^n) paths, which quickly
exhausts the backtrack limit for large bounds.

Fix this by compiling the optional tail via a RepeatStart/RepeatCheck
counted loop when the atom is known to be non-zero-width. The loop
is safe to use without a progress check precisely because the atom
cannot match empty.

This required making atom_can_be_zero_width recursive into group bodies:
previously it conservatively returned true for all Group and
NonCapturingGroup atoms, so the non-zero-width guard could never fire
for grouped subexpressions.

The old lowering triggered "Regular expression backtrack limit exceeded"
for patterns like /'(?:\\(?:\r\n|[\s\S])|[^'\\\r\n]){0,32}'/, causing
inputs that should match normally (or return null) to throw instead.

Fixes syntax highlighting of the C++ API on https://blend2d.com

2026-04-11 18:43:48 +02:00

..

src

LibRegex: Avoid hitting backtrack limit for bounded grouped repetitions

2026-04-11 18:43:48 +02:00

build.rs

Meta: Make Rust FFI headers reproducible

2026-03-31 15:59:04 +02:00

Cargo.toml

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cbindgen.toml

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