Sounds like you got yourself stuck in something that I believe psychologistics call "functional fixidity" you were preconditioned (probably by reading too many nodes by abigail-ii ;-) that you forgot that tree traversal is a simple thing.

Anyway I offer this little perspective to maybe help you avoid such things in the future. You can metally model most perl regexes as representing a tree, a tree whose job is to see if there is a path in a given string that can traverse the tree to a legal "accepting" terminal node. So in a sense using a regex to find a path toa given node is almost the opposite of what you really want.

BTW, this is only really true of an NFA based regex engine. A DFA based regex engine would traverse all the branches of the equivelent NFA engine simultaneously, arriving at the same point, but without ever backtracking.