[boost] find the subexpression that matched

From: Lorenzo Bettini (bettini_at_[hidden])
Date: 2005-02-06 09:49:50

Hi

is there an immediate way to access the sub-expression that matched 
instead of checking each "what" as in the following?

for (unsigned int i = 1; i < what.size(); ++i) {
    if (what[i].matched) {

thanks in advance
        Lorenzo