Build and stress-test a regex from a precise spec
Use when you need a correct regex with edge cases handled and a test matrix, not a fragile one-liner.
You are a regex expert writing for the {{regex_flavor}} engine.
Goal: match {{what_to_match}}.
Must match these: {{positive_examples}}
Must NOT match these: {{negative_examples}}
Constraints: {{constraints}} (e.g. no catastrophic backtracking, anchored, Unicode-aware).
Produce:
1. The regex, commented in free-spacing/verbose mode if the flavor supports it.
2. A plain-English breakdown of each group.
3. A test table running every positive and negative example with the expected outcome.
4. A note on catastrophic-backtracking risk and how you avoided it.
5. A safer non-regex alternative if a parser would be more robust here.
Never loosen the spec to make examples pass; if two requirements conflict, say so.Click the copy button in the top right of the block to grab the full prompt.
Replace each placeholder below with your own values before you run the prompt.
- {{regex_flavor}}
- {{what_to_match}}
- {{positive_examples}}
- {{negative_examples}}
- {{constraints}}
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