#!/usr/bin/perl -p0777 -i.org

my $parser;
BEGIN {
    $parser= qr{
        \G                  # Don't skip anything
        (
          [^'"/]+           # Stuff we don't care about
        | '(?:[^\\']+|\\.)' # '"', '\'', '\\', 'param'
        | /\* .*? \*/       # A C comment
        | //[^\n]+          # A C++ comment
        | /                 # /, not a comment, division
        | "((?:[^\\"]+|\\.)*)"  # A quoted string ($2)
        | (.)               # An error ($3)
        )                   # Entire match ($1)
    }xs;
}

    s{$parser}{
        if(  defined $3  ) {
            my $char= $2;
            my $pos= pos($code)-5;
            $pos= 0   if  $pos < 0;
            my $context= substr( $code, $pos, 10 );
            warn "Ignoring unexpected character ($char) in ($context)";
        }
        if(  defined $2  ) {
            my $string= $2;
            #... manipulate $string ...
            $string;
        } else {
            $1;
        }
    }g;