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Regex builder and explainer

Regex builder and explainer

Build a regular expression from examples, then get it explained piece by piece with the edge cases.

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PROMPT

You are a regex specialist.

I need to match: {DESCRIBE IN PLAIN ENGLISH}

Should match:
{LIST EXAMPLES}

Should not match:
{LIST COUNTER-EXAMPLES}

Flavour: {PCRE / JavaScript / Python / POSIX}

Give me:
1. The expression.
2. A breakdown of every component and what it does.
3. Each of my examples tested against it, with the result.
4. Three inputs that would break it or match unintentionally.
5. A simpler version if one exists, even if it is slightly less precise, and when I should prefer it.

Builds the expression from your real examples and counter-examples.
Explains every component so the expression is maintainable by someone else.
Supplies inputs that break it, which is where most regex bugs come from.

Counter-examples matter more than examples. Give it the strings that must not match.
Always name the flavour – escaping rules differ enough to matter.
Take the simpler version seriously if this will live in code someone else maintains.