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That was a fantastic demonstration of what backtracking meant. Thank you John for your in depth description of what went wrong. As a follow up, would something

That was a fantastic demonstration of what backtracking meant. Thank you John for your in depth description of what went wrong. As a follow up, would something like `[^=]=.` be a better capture group regex?

jalada 7y ago
Yes. I think HN stole your asterisks. You meant: /.*=.*/ becomes /[^=]*=.*/ That is, zero or more 'not-equals-sign-characters', followed by an equals sign. Where the first regex is 57 steps for x=xxxxxxxxxxxxxxxxxxxxxxxx, the second is just 7. Avoid using greedy .* for backtracking regex engines! Give your greedy regex engine the hints it needs to do what it does best.
- Thorrez 7y ago
  The article says that even lazy matches can have catastrophic backtracking.
- wbl 7y ago
  Don't use a backtracking regex engine is probably the better lesson. I want a tool that won't unexpectedly poke me with the sharp bit.