How can I substitute the nth occurrence of a match in a Perl regex?

Question

Following up from an earlier question on extracting the n\'th regex match, I now need to substitute the match, if found.

I thought that I could define the extraction

Answer 1

Reworking an answer to an earlier question, match n-1 times and then replace the next. Memoizing patterns spares poor Perl having to recompile the same patterns over and over.

my $_quoted = qr/'[^']+'/; # ' fix Stack Overflow highlighting
my %_cache;
sub replace_nth_quoted { 
  my($string,$index,$replace) = @_;
  my $pat = $_cache{$index} ||=
    qr/ ^
        (                    # $1
          (?:.*?$_quoted.*?) # match quoted substrings...
            {@{[$index-1]}}  # $index-1 times
        )
        $_quoted             # the ${index}th match
      /x;

  $string =~ s/$pat/$1$replace/;
  $string;
}

For example

my $string = "'How can I','use' 'PERL','to process this' 'line'";
print replace_nth_quoted($string, 3, "'Perl'"), "\n";

outputs

'How can I','use' 'Perl','to process this' 'line'