#!/usr/bin/perl
#
# $Id: condhtml,v 1.2 1997/09/10 01:25:09 earl Exp $
#
# Copyright (c) 1997 by Earl A. Killian.
#
# This file is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation version 1.
#
# This file is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this file; see the file COPYING.  If not, write to the
# Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

$myname = 'condhtml';

# parse options
while ($#ARGV >= 0 && $ARGV[0] =~ /^-D/) {
  $_ = $';
  $v = 1;
  if (/=/) {
    $_ = $`;
    $v = $';
  }
  $value{$_} = $v;
  shift (@ARGV);
}

$line = 0;	# current line number
$on = 1;

@name = ();
@v = ();
@on = ();
@line = ();	# for error messages

while (<>) {
  $line += 1;
  if (/\<\!\-\-\s+if (\!?)(\S+) --\>/) {
    push (@name, $2);
    push (@v, $v);
    push (@on, $on);
    push (@line, $line);
    $v = $value{$2};
    if (!defined($v)) {
      print if $on;
    } else {
      $v = !$v if $1 eq '!';
      $on = $on[$#on] && $v;
    }
  } elsif (/^\<\!--\s+else --\>$/) {
    if ($#name < 0) {
      print STDERR "$myname: else without matching if on line $line.\n";
    } elsif (!defined($v)) {
      print if $on;
    } else {
      $v = !$v;
      $on = $on[$#on] && $v;
    }
  } elsif (/^\<\!--\s+endif (\S+) --\>$/) {
    if ($#name < 0) {
      print STDERR "$myname: endif without matching if on line $line.\n";
    } else {
      print if $on && !defined($v);
      $n = pop(@name);
      if ($n ne $1) {
	print STDERR "$myname: if/endif mismatch on line $line: $n/$1.\n";
      }
      $on = pop(@on);
      $v = pop(@v);
      pop(@line);
    }
  } else {
    print $_ if $on;
  }
}

while ($#name >= 0) {
  print STDERR "$myname: missing endif ", pop(@name), " for if on line ", pop(@line), ".\n";
}

# 
# Local Variables:
# mode:perl
# perl-indent-level:2
# End: