Re: Two-dimensional match/regex?

[Anonymous Monk]

Here's a subroutine that solves the problem if you want an *exact* match - no regex supported. The solution can be extended to regexes, but you have to be careful, iterating with m//g over a line to "find all matches" will fail, as m//g will never find overlapping matches.

sub multi_match {
    my ($large, $small) = @_;

    my @large = split /\n/ => $large;
    my @small = split /\n/ => $small;
        
    my $first = $small [0];
            
    foreach my $i (0 .. @large - @small) {
        my $pos = 0;
      LOOP:
        while ((my $new_pos = index ($large [$i], $first, $pos)) != -1
+) {
            $pos = $new_pos + 1;
            foreach my $j (1 .. $#small) {
                next LOOP unless
                     length $large [$j] >= $new_pos + length $small [$
+j] &&
                     $small [$j] eq substr $large [$i + $j], $new_pos,
                                           length $small [$j];
            }
            return ($i, $new_pos);
        }
    }
    return;
}