Suitable libraries for implementing a "push"-type matching engine?

[Andrew Warkentin]

I am trying to write a matching engine for a matching language for a 
filtering proxy compatible with that of The Proxomitron. The matching 
language is basically an extended superset of shell-style globs, with 
functionality comparable to regexps (see 
http://www.proxomitron.info/45/help/Matching%20Rules.html). Can anyone 
recommend any Python libraries that would be suitable for my purposes? I 
think that I can implement a parser for the patterns themselves with 
pyparsing, but I'm not sure if anything suitable for finding matches in 
an input stream of text exists. I don't want to reinvent the wheel if I 
don't have to.

A matching engine for a filtering proxy has to be able to handle partial 
input and "hold" data until enough is received to determine whether 
there is a match (or else the entire document would have to be held 
until the end is reached, filtered, and then sent all at once to the 
remote client, and that would make it appear much less responsive and 
possibly break some applications). I also need to be able to associate 
specific patterns (matching commands and certain backslash-escapes) with 
functions that are called to determine if they match.