# REMOVE COMMENTS FROM C++ CODE

# ORIGINAL BY Helmut Jarausch
# EXTENDED BY Damian Conway AND Helmut Jarausch AND Jeremy Braun

use strict;
use Parse::RecDescent;

use vars qw/ $Grammar /;

my $parser = new Parse::RecDescent $Grammar  or  die "invalid grammar";

undef $/;
my $text = @ARGV ? <> : <DATA>;

$parser->program($text) or die "malformed C program";

print "Comments\n========\n$parser->{comments}\n";
print "\nCode\n====\n$parser->{code}\n";
print "\nStrings\n=======\n", map(qq{\t"$_"\n}, @{$parser->{strings}});

BEGIN
{ $Grammar=<<'EOF';

program    : <skip:''> { @{$thisparser}{qw(comments code strings)} = () }
      part(s)

part    : comment { $thisparser->{comments} .= $item[1];
                $thisparser->{code}     .= " "; }
        | C_code  { $thisparser->{code}     .= $item[1]; }
        | string  { $thisparser->{code}     .= qq("$item[1]");
            push @{$thisparser->{strings}}, $item[1]; }
        | charlit  { $thisparser->{code}     .= qq('$item[1]');
            push @{$thisparser->{strings}}, $item[1]; }

C_code  : m{(
          [^"/]+        # one or more non-delimiters
          (            # then (optionally)...
           /        # a potential comment delimiter
           [^*/]        # which is not an actual delimiter
          )?        #
        )+            # all repeated once or more
       }x

string    : m{"            # a leading delimiter
        ((            # zero or more...
          \\.        # escaped anything
          |            # or
          [^"]        # anything but a delimiter
         )*
        )
        "}x
        { $return =  $1 }

charlit    : m{'            # a leading delimiter
        ((            # zero or more...
          \\.        # escaped anything
          |            # or
          [^']        # anything but a delimiter
         )*
        )
        '}x
        { $return =  $1 }

comment    : m{\s*            # optional whitespace
        //            # comment delimiter
        [^\n]*        # anything except a newline
        \n            # then a newline
       }x

    | m{\s*            # optional whitespace
        /\*            # comment opener
        (?:[^*]+|\*(?!/))*    # anything except */
        \*/                # comment closer
            ([ \t]*)?           # trailing blanks or tabs
       }x

EOF
}
__DATA__
program test; // for decomment

// using Parse::RecDescent

int main()
{
/* this should
   be removed
*/
  char *cp1 = "";
  char *cp2 = "cp2";
  char c3   = 'c';
  int i;  // a counter
          // remove this line altogehter
  int k;
      int more_indented;  // keep indentation
      int l;  /* a loop
             variable */
      // should be completely removed

  char *str = "/* ceci n'est pas un commentaire */";
  return 0;
}