Regex to validate regex [closed]

Duplicate of http://stackoverflow.com/questions/362793/regexp-that-matches-valid-regexps

How do you produce a regex that matches only valid regex?

For instance: "[hc]at" would be valid (matching "hat" and "cat"), but "[hcat" would be invalid, as it is missing ].

From stackoverflow

• In general, no, because nested pairs of parens and brackets, etc., is something you need a recursive descendant parser (or similar) to handle.

• In Java you can check a regular expression by calling

  // Create a pattern to match breaks
      Pattern p = Pattern.compile("[,\\s]+");
  

  compile methode throws PatternSyntaxException if the expression's syntax is invalid

• This question has been asked and answered before:

  http://stackoverflow.com/questions/362793/regexp-that-matches-valid-regexps

• Use the right tool for the job. A better solution would be to use the RegEx class of the language you are using.

  Something like:

  >  Regex rx = new Regex("[INVALID REGEX
  > HERE");  if(rx.Valid())  {    ...  }