A search engine configured to determine whether an input string including a plurality of input characters matches a regular expression including an inexact pattern including a specified range of instances of pattern characters each belonging to a specified set of characters, the search engine including a microcontroller having an input to receive a microprogram embodying the inexact pattern, a first co-processor coupled to the microcontroller and dedicated to determine whether each input character in a first portion of the input string is a member of the specified set of characters, and a second co-processor coupled to the microcontroller and dedicated to determine whether the number of input characters in the first portion of the input string falls within the specified range.