$string1 = 'foo';
$string2 = 'bar';

@in_strings = (
               'blue15midget_bar',
               'this is an exception',
               'blue17midget_foo',
               'deep13gizmonic_bar',
               'another exception',
               'red12dwarf_foo',
               'red12dwarf_bar',
               'exception containing _foo',
               );



%string_table = ();
foreach my $in_string (@in_strings) {
    if ( $in_string =~ m{(.+) (\d{2,2}) (.+) _ ($string1 | $string2 ) $ }x \
) {
        $string_table{$in_string} = {
            initial => $1,
            number => $2 + 0,
            another => $3,
            ending => $4,
        };
    }
    else {
        $string_table{$in_string} = 'EXCEPTION';
    }
}