#!/usr/bin/perl
  
  if (@ARGV != 3) {
  	print STDERR "Use:
  ";
  	print STDERR "  showdf <showg-script> <old-file> <new-file>
  ";
  	print STDERR "to create a showg diagram of glyphs differing in two files
  ";
  	exit 1;
  }
  
  $cmd = shift @ARGV;
  $oldf = shift @ARGV;
  $newf = shift @ARGV;
  
  open(O, "<$oldf") or die "Unable to open '$oldf'
  ";
  open(N, "<$newf") or die "Unable to open '$newf'
  ";
  
  while(<O>) {
  	last if(/CharStrings/);
  }
  while(<N>) {
  	last if(/CharStrings/);
  }
  
  undef @symlist;
  $sym = '';
  $inlist = 0;
  $nstop = 0;
  
  while($so = <O>) {
  	if($so =~ m|^(/\S+)\s+\{|) {
  		$sym = $1;
  		$inlist = 0;
  		#printf STDERR "found sym $sym
  ";
  		if (!$nstop || $sn !~ m|^$sym\s+\{|) {
  			while($sn = <N>) {
  				#print STDERR "+$sn";
  				last if($sn =~ m|^${sym}\s+\{|);
  			}
  		}
  		$nstop = 0;
  	} elsif(!$nstop) {
  		$sn = <N>;
  		#print STDERR "<$so>$sn
  ";
  		if($so ne $sn) {
  			if(!$inlist) {
  				$inlist = 1;
  				push(@symlist, $sym);
  			}
  			if($sn =~ m|^(/\S+)\s+\{|) {
  				$nstop = 1;
  				#printf STDERR "stop at $1
  ";
  			}
  		}
  	}
  }
  unshift(@symlist, $cmd, '-c', $oldf, $newf);
  #printf("%s
  ", join(' ', @symlist));
  exec @symlist;