#!/usr/bin/perl

# comments.pl
# by Richard Lawrence 2001
# Correctly comments #endif's in line with their associated #ifdef,
# #ifndef and #if.
#
# usage:  comments.pl <filename>
#
# Not fully tested. Use at own risk
#

use strict;
my @define;

open(FILE, "$ARGV[0]") || die "Can't open $ARGV[0] to read: $!";
while(<FILE>)
{
  chomp;
  if (/^ *\#if (.+)/ || /^\#ifdef (.+)/)
  {
    push @define, $1;
    print "$_\n";
  }
  elsif (/^ *\#ifndef (.+)/)
  {
    push @define, "!$1";
    print "$_\n";
  }
  elsif (/^( *)\#else/)
  {
    my $len = @define;
    my $def = invert($define[$len-1]);
    print "$1#else /* $def */\n";
  }
  elsif (/^( *)\#endif/)
  {
    my $def = pop @define;
    print "$1#endif /* $def */\n";
  }
  else
  {
    print "$_\n";
  }
}
close FILE;

exit(0);

sub invert
{
  my $f = substr($_[0], 0, 1);
  return substr($_[0], 1, length($_[0])) if ($f eq "!");
  return "!$_[0]";
}