XML-Schema type regex or pattern for regex

Question

I want to validate if a certain attribute is a valid regex. Is there some direct built in type in xml schema maybe xs:regex ?

Otherwise is there a regex that defines valid regexes?

Answer 1

There is, by definition, no regex that can validate regular expressions.

Regular expressions can match regular languages, they are not themselves a regular language. Much like there can be no regular expression to validate HTML or JavaScript.

To find out if a string is a legal regular expression, it's easiest to try and create a regex object from it. In XSD itself this is impossible, so you'd need the help of an external tool.