fix lua regex causing runaway backtracking. #2882
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This was referenced Apr 5, 2025
andersk
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May 5, 2025
pygments/lexers/scripting.py
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| if sys.version_info >= (3, 11): | ||
| # Use a possessive quantifier to prevent greediness from causing runaway backtracking. | ||
| _space = r'(?:\s++)' | ||
| else: | ||
| # Possessive quantifiers are not available in Python < 3.11. Complex Lua is likely to | ||
| # cause any regex that includes _space to take an exponentially long time. | ||
| _space = r'(?:\s+)' |
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A negative lookahead assertion works in all Python versions.
_space = r'(?:\s+(?!\s))'
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Nice that makes sense. I fixed it up and it works as far as I can tell. Thanks for helping simplify.
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Tested, works here - appreciate the investigation!
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Use negative lookahead to avoid runway backtracking in whitespace. Fixes pygments#2839
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Queued for Pygments 2.19.2, thanks guys! |
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Use possessive quantifier if possible, otherwise fallback to old, buggy regex.
Fixes #2839
For reference, see: