Rust Regex Engine Gains Captureless Lookbehinds
2025-07-15
The official Rust regex engine now supports captureless lookbehinds, a powerful regex feature enabling assertions about preceding text without capturing the match. Implementation involved modifications to the regex automata and compiler, overcoming performance hurdles like unnecessary scans to the end of the text and quadratic time complexity in match-all searches. Benchmarking demonstrates good performance, competitive with Python's `re` library in most cases.
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