Regular Expression Pattern Matching "State" Object

[Dubois, Jeff]

I am looking for a regular expression object\algorithm that does something
like the following:

    1. Initialize  the object with a regular expression pattern.
    2. After initializing the object with a regular expression pattern you
are able to "feed" the object a sequence of characters, one character at a
time, where, after each character is fed to the object, the object indicates
whether or not it is still in a "continuing to match" state, "not a match"
state, or a "match complete" state.  

I am thinking that such a utility may be useful when searching for strings
across DOM nodes for example.

Thanks!

Jeff