zsh implementation question

[Eric.D.Friedman@xxxxxxxxxxxxxx]

Would one of the zsh developers kindly point me to the source code that zsh
uses for partial string matching on the command line?  Is it implemented as
a brute force search over an array of possible values, or does zsh use
something fancier like patricia tries to determine that "appl" matches
{"application", "apple", "applied"} from the set {"application",
"apothecary", "apple", "applied", "moose"} ?

I'm writing a GUI in which I'd like to offer similar completion capabilities
(also found in many web browsers).  The set of possible matches will always
be pretty small (smaller than what zsh deals with), so it seemed like this
was a good place to look for a reasonable implementation/inspiration.

Thanks,
Eric