anagrep

Find strings with permutations (anagrams) that match a regular expression.

Given a regular expression, determine if it matches any permutation of a given string. For example, "lt[aeiou]*" would match all strings with one 'l', one 't', and vowels (like "elate", "tail", "tl", etc.). Regular expression parsing is based on regex-tdfa and generally follows those semantics, but not all regular expression features are supported. For example, repeat modifiers cannot be applied to groups (such as "(abc)*"). The goal is for matching to be fairly efficient in most cases, given that this problem is NP-complete.