New answers tagged regular-expressions
0
You can test a regular expression on a document with M-x re-builder and build it interactively. Faulty parts are highlighted.
3
If you want to check it interactively:
(defcustom foo "" "foo" :type 'regexp :group 'emacs)
Try giving it an invalid regexp and setting it, and it will raise an error.
Or if you want to test it programmatically, this predicate returns t for valid and nil for invalid, and when invalid it shows a message with the error type.
(defun regexp-...
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