#!/usr/local/bin/perl -w
# $Header: /usr/local/svn/cvs-repositories/numrelcvs/AEIThorns/AHFinderDirect/src/misc/mpp,v 1.2 2002-09-16 14:17:44 jthorn Exp $

my $help_msg = <<'EOF';
Usage:
   mpp  [ -Dfoo -DBAR ... ]  [ --debug ]  <input.maple  >output.mm
or
   mpp  --help

This program is a preprocessor for Maple source code.  It's modeled
after a subset of the C preprocessor (cpp), but with a Maple-flavored
syntax: preprocessor directives use @ as the marker character, instead
of cpp's #.  The @include, @ifdef, @ifndef, @else, and @endif directives
are supported with the same syntax and semantics as the corresponding
cpp directives, except that
   @include "filename" optional_text
prints   optional_text   (if present) on a separate line following the
contents of the include file.

There may be white space on a line before the '@' which introduces a
preprocessor directive, but no white space between '@' and the directive
name.

Command line arguments of the form  -Dname  define macros, whose
existence may be tested with @ifdef, @ifndef, @else, and/or @endif as
usual.  For example, one might write
	@ifdef MAPLE_V_RELEASE_3
	  words(0):
	  gc(0):
	@else
	  kernelopts(printbytes=false);
	@endif
to disable Maple's printing of 'bytes used' messages.
EOF

###############################################################################

#
# ***** copyright notice and licensing terms *****
#

#
# Copyright (C) 2000, Jonathan Thornburg <jthorn@thp.univie.ac.at>
#
# This program 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; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 program; see the file COPYING.  If not, write to
# the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
# MA 02111-1307, USA.
#

###############################################################################

#
# ***** table of contents *****
#

#
# <<<help message>>>
# <<<copyright notice and licensing terms>>>
# <<<this table of contents>>>
# <<<global data structures>>>
# main - driver
# process - recursive function to copy a named file to standard output
#
# dirname - find directory part of file name
#

###############################################################################

#
# ***** global data structures *****
#

#
# This hash table records macros:
#    key = macro name
#    value = macro definition
#
my %macro_table = ();

###############################################################################

#
# ***** main program *****
#

use strict;
use integer;
use FileHandle;

#
# constants
#

# arguments for process()
my $true = 1;
my $false = 0;

# arguments for process()
my $read_to_endif = 0;
my $read_to_else_or_endif = 1;
my $read_to_eof = -1;

# results from process()
my $got_endif = 0;
my $got_else = 1;
my $got_eof = -1;

#
# command line handling
#

my $debug = 0;

if ((scalar(@ARGV) == 1) && ($ARGV[0] eq '--help'))
	{ print $help_msg; exit(0); }

	while (my $arg = shift(@ARGV))
	{
	if    ($arg eq '--debug')
		{ $debug = 1 }
	elsif ($arg =~ /^-D(.*)$/)
		{
		my $macro_name = $1;
		if ($debug)
			{ print "defining macro :$macro_name:\n"; }
		$macro_table{$1} = 1;
		}
	else
		{ die("mpp: bad argument \"$arg\"!\n"); }
	}

process(new FileHandle('< -'), '(standard input)', 1,
	$true, $read_to_eof);
exit;

###############################################################################

#
# This (recursive) function reads input lines from a FileHandle, and
# interprets preprocessor directives (making recursive calls for each
# @include or @ifdef).  It either prints non-preprocessor lines or
# discards them, depending on a flag argument.  This function returns
# when it either reaches end of file on the FileHandle, or sees an
# @else or @endif line.
#
# Arguments:
# $fh = The FileHandle from which to copy data.
# $file_name = The file name corresponding to $fh.  This is (only) used
#	       for formatting error messages.  An empty string denotes
#	       standard input.
# $line_number = The line number within $file_name at which $fh is positioned.
#		 This is (only) used for formatting error messages.
# $print_flag = A Boolean flag:
#		$true  ==> Print non--preprocessor-directive input lines.
#		$false ==> Ignore non--preprocessor-directive input lines.
# $how_to_finish = A flag specifying how we finish our processing:
#	$read_to_endif         ==> We expect to finish by seeing an @endif.
#	$read_to_else_or_endif ==> We expect to finish by seeing either an
#				   @else or an @endif.
#	$read_to_eof           ==> We expect to finish by reaching
#				   end-of-file on the input.
#	In any case, we  die(...)  if we finish due to a wrong reason.
#
# Results:
# This function returns a 2-element list
#	($final_line_number, $how_finished)
# where
#	$final_line_number = The value of $line_number for the last input
#			     line read
#	$how_finished = Describes which termination condition actually
#			caused us to finish:
#			$got_endif ==> We saw an @ifdef
#			$got_else  ==> We saw an @else
#			$got_eof   ==> We reached end-of-file on the input
#
sub process
{
my ($fh, $file_name, $line_number, $print_flag, $how_to_finish) = @_;

# special-case standard input
my $stdin_flag = ($file_name eq '');
if ($file_name eq '')
	{ $file_name = '(standard input)'; }

if ($debug)
	{
	print
  "process(\"${file_name}\", line ${line_number}):\n",
  "        print_flag = :${print_flag}:   how_to_finish = :${how_to_finish}:\n";
	}

# main data loop
	for ( ; my $line = <$fh> ; ++$line_number)
	{
	# not an @ directive
	if    ($line !~ /^\s*@/)
		{
		if ($print_flag)
			{ print $line; }
		next;					# *** LOOP CONTROL ***
		}

	# @include
	elsif ($line =~ /^\s*\@\s*include\s+"([^"]+)"(.*)$/)
		{
		my $include_file_name = $1;
		my $suffix = $2;
		if ($debug)
			{
			print "got \@include :$include_file_name:",
			      "   suffix = :$suffix:\n";
			}

		if ($print_flag)	# if we're discarding lines, we can
					# skip processing the @include file,
					# since @ifdef ... @endif directives
					# are (assumed to be) always properly
					# nested with respect to @include
			{
			# open the @include file
			# ... first look for it in (relative to) current dir,
			#     failing that, try directory of file containing
			#     @include
			my $include_fh = new FileHandle("< $include_file_name");
			if ((! defined $include_fh) && (! $stdin_flag))
				{
				my $dir = dirname($file_name);
				my $include_fh
					= new FileHandle(
					      "< $dir/$include_file_name"
							);
				}
			if (! defined $include_fh)
				{
				die(
	   "***** mpp: unable to open \@include file \"$include_file_name\"\n",
	   "           at input file \"$file_name\", line $line_number\n"
				   );
				}

			# recursive call to process @include file
			process($include_fh, $include_file_name, 1,
				$true, $read_to_eof);
			$include_fh->close();

			# print any suffix
			print "$suffix\n";
			}
		}

	# @ifdef
	elsif ($line =~ /^\s*\@\s*if(n?)def\s+(\S+)/)
		{
		my $negate_flag = ($1 eq 'n');
		my $macro_name = $2;
		if ($debug)
			{
			print "got \@ifdef/\@ifndef:",
			      "   macro_name = :${macro_name}:",
			      "   negate_flag = :${negate_flag}:\n";
			}
		my $macro_is_defined = (exists $macro_table{$macro_name});
		my $doit_flag = $negate_flag ? (! $macro_is_defined)
					     : $macro_is_defined;
		if ($debug)
			{
			print "==> macro_is_defined = :${macro_is_defined}:",
			      "   doit_flag = :${doit_flag}:\n";
			}

		# recursive call to process body of @ifdef
		my ($final_line_number, $how_finished)
			= process($fh, $file_name, $line_number+1,
				  $print_flag && $doit_flag,
				  $read_to_else_or_endif);
		$line_number = $final_line_number;
		if ($how_finished == $got_else)
			{
			# recursive call to skip @else text
			($final_line_number, $how_finished)
				= process($fh, $file_name, $line_number+1,
					  $print_flag && !$doit_flag,
					  $read_to_endif);
			$line_number = $final_line_number;
			}
		}

	# @endif
	elsif ($line =~ /^\s*\@\s*endif/)
		{
		if (    ($how_to_finish == $read_to_endif)
		     || ($how_to_finish == $read_to_else_or_endif)    )
			{
			return ($line_number, $got_endif);# *** EARLY RETURN ***
			}
		   else {
			die(
   "***** mpp: \@endif when not within the scope of an \@ifdef\n",
   "           at input file \"$file_name\", line $line_number\n"
			   );
			}
		}

	# @else
	elsif ($line =~ /^\s*\@\s*else/)
		{
		if ($how_to_finish == $read_to_else_or_endif)
			{
			return ($line_number, $got_else); # *** EARLY RETURN ***
			}
		   else {
			die(
   "***** mpp: \@else when not within the scope of an \@ifdef\n",
   "           at input file \"$file_name\", line $line_number\n"
			   );
			}
		}

	else	{
		die(
   "***** mpp: unknown @-directive \"$line\"!\n",
   "           at input file \"$file_name\", line $line_number\n"
		   );
		}
	}

if ($how_to_finish != $read_to_eof)
	{
	die(
   "***** mpp: unexpected end-of-file (i.e. unterminated \@ifdef)\n",
   "           at input file \"$file_name\", line $line_number\n"
	   );
	}
return -1;
}

###############################################################################
###############################################################################
###############################################################################

#
# This function computes the directory part of a file name.
# It is (should be) identical in effect to the  dirname(1)  program.
#
sub dirname
{
my ($file_name) = @_;

# strip off reundant trailing /
if (($file_name =~ /\/$/) && ($file_name ne '/'))
	{ $file_name = substr($file_name, 0, length($file_name)-1); }

if (index($file_name, '/') >= 0)
	{
	# $file_name contains a /
	$file_name =~ s:/[^/]+$::;
	if ($file_name eq '')
		{ $file_name = '/'; }
	}
   else {
	# $file name doesn't contain a /
	$file_name = '.';
	}

return $file_name;
}