qr/^ ab\+cd \(12\)34$/
qr/^\s{2}[a-z]{2}\+[a-z]{2}\s{3}\(\d{2}\)\d{2}$/
qr/^\s+[a-z]+\+[a-z]+\s+\(\d+\)\d+$/
qr/^\s+\S+\s+\S+$/
####
$str = ' ab+cd (12)34';
$str = quotemeta($str);
$str =~ s/[a-z]/\[a-z\]/ig;
$str =~ s/\d/\\d/g;
$str =~ s/\s+/\\s\+/g;
$pat = qr/$str/i;
print "$pat\n";
Output:
(?i-xsm:\\s+\\s+[a-z][a-z]\+[a-z][a-z]\\s+\\s+\\s+\(\d\d\)\d\d)
##
##
$str = ' ab+cd (12)34';
$str = quotemeta($str);
$str =~ s/\\ / /g;
$str =~ s/[a-z]/\[a-z\]/ig;
$str =~ s/\d/\\d/g;
$str =~ s/\s+/\\s\+/g;
$pat = qr/$str/i;
print "$pat\n";
Output:
(?i-xsm:\s+[a-z][a-z]\+[a-z][a-z]\s+\(\d\d\)\d\d)