use String::Approx 'amatch';
use re 'eval';
use re 'debug';

$r = qr/((?:@{[ ramatch( 'APT' ) ]}\s)?\w+\d)$/;
$apt = ( "5678 DELAWARE AVENUE AOT 123" =~ $r )[0];

$\ = "\n";
print "\$apt=$apt";

sub ramatch {
    my $match = shift;
    my $match_len = length $match;
    $match =~ s(\\)(\\\\)g;
    $match =~ s(')(\\')g;
    return
        "(?x:\Q$match\E |
             (?(?{scalar amatch('$match',substr(\$_,pos(),$match_len))})
               (?s:@{[ q[.] x $match_len]}) |
               (?!)))";
}

##</code><code>##

# This version wasn't very nice so I replaced it and commented it out.
#use String::Approx 'amatch';
#use re 'eval';
#
#$r = qr/(@{[ ramatch( 'APT' ) ]}\s\w+\d)$/;
#$apt = ( "5678 DELAWARE AVENUE APT 123" =~ $r )[0];
#
#$\ = "\n";
#print "\$apt=$apt";
#
#sub ramatch {
#    my $match = shift;
#    my $match_len = length $match;
#    # escape $match
#    our $ONCE = 0;
#    return
#        "(?x:(?(?{\$ONCE += amatch('$match',substr(\$_,pos(),$match_len));
#                  \$ONCE>1})
#               (?s:@{[ q[.] x $match_len]}) |
#               (?!)))";
#}