#! perl -slw
use strict;
use Macro;

MACRO sub fred {
	my( $a, $b, $c ) = @_;
	return ( $a + $b ) * $c;
}
ENDMACRO

my( $x, $y, $z ) = ( 1, 4, 7 );
print fred( $x, $y, $z );

for my $x ( 1 .. 10 ) {
	print fred( $x, $y, $z );
}
__END__
P:\test>435608
35
35
42
49
56
63
70
77
84
91
98

##</code><code>##

my( $x, $y, $z ) = ( 1, 4, 7 );
print do{
    our $MACRO_RETURN;
    local $MACRO_RETURN;
    $MACRO_RETURN = ( $x + $y ) * $z; goto MACRO_RETURN;;
    MACRO_RETURN: $MACRO_RETURN
};

for my $x ( 1 .. 10 ) {
        print do{
            our $MACRO_RETURN;
            local $MACRO_RETURN;
            $MACRO_RETURN = ( $x + $y ) * $z; goto MACRO_RETURN;;
            MACRO_RETURN: $MACRO_RETURN
       };
}

##</code><code>##

package Macro;
use strict;
use warnings;
use Filter::Simple;

my %macros;

FILTER_ONLY 
executable => sub { 
	while( 
		s[
			MACRO\s+
			sub\s+
			(\w+)\s+
			\{\s+
			my\s*\( \s* ( [^\)]+? ) \s* \)\s* =\s* \@_;\s+
			( .*? )
			\} \s* 
			ENDMACRO
		][]xsmg 
	) {
		my( $name, $args, $body ) = ( $1, $2, $3 );
		$body =~ s[[\r\n]+][]g;
		$macros{ $name } = [ 
			[ split ',\s*', $args ], 
			"do{
				our \$MACRO_RETURN;
				local \$MACRO_RETURN;
				$body; 
				MACRO_RETURN: \$MACRO_RETURN 
			}" 
		];
	}
	
	for my $macro ( keys %macros ) {
		s[
			$macro\( \s* ( [^\)]+ ) \s* \)
		]{
			my @actual = split '\s*,\s*', $1;
			my @formal = @{ $macros{ $macro }[ 0 ] };
			my $do = $macros{ $macro }[ 1 ];
			my %substs; @substs{ @formal } = @actual;
			$do =~ s[([\$][\w]+)]{ 
                       exists $substs{ $1 } ? $substs{ $1 } : $1 
                  }eg;
			$do =~ s[return\s*(.*?)\s*;]
                       [\$MACRO_RETURN = $1; goto MACRO_RETURN;]g;
			$do;
		}xeg;
	}
	$_;
};


1;