Does pgsql's regex processor optimize Common-Prefix?

Hi all.
I am developing an application which searches for city names in a
column. There is a lot of cities and I have to 'like' every name which
is not effective enough. So I want to know whether pgsql's regex
processor can optimize regexes such as:

Nebraska|Nevada|North Carolina
to
N(e(braska|vada)|orth Carolina)

If the processor can do that like a Dictionary-Tree, it may be
affordable to me or else I have to write a matcher myself.

Any suggestion is appreciated. Thank you and appologize for my poor English.

--Xig