my (@matches) = ($line =~ $re)
    if (defined $&) {
        $cb->(@matches);
        last;
    }    

##</code><code>##

    
    if ( my (@caps) = ($line =~ $re) ) {
        @caps = () if $caps[0] ne $1;           # reset pseudo captures
        $cb->(@caps);
        last;
    }