# Original by Nathan Torkington, massaged by Jeffrey Friedl
#
sub preserve_case($$)
{
my ($old, $new) = @_;
my ($state) = 0; # 0 = no change; 1 = lc; 2 = uc
my ($i, $oldlen, $newlen, $c) = (0, length($old), length($new));
my ($len) = $oldlen < $newlen ? $oldlen : $newlen;
for ($i = 0; $i < $len; $i++) {
if ($c = substr($old, $i, 1), $c =~ /[\W\d_]/) {
$state = 0;
} elsif (lc $c eq $c) {
substr($new, $i, 1) = lc(substr($new, $i, 1));
$state = 1;
} else {
substr($new, $i, 1) = uc(substr($new, $i, 1));
$state = 2;
}
}
# finish up with any remaining new (for when new is longer than old)
if ($newlen > $oldlen) {
if ($state == 1) {
substr($new, $oldlen) = lc(substr($new, $oldlen));
} elsif ($state == 2) {
substr($new, $oldlen) = uc(substr($new, $oldlen));
}
}
return $new;
}
$a = "this is a TEsT case";
$a =~ s/(test)/preserve_case($1, "success")/gie;
print "$a\n";
This prints:
this is a SUcCESS