#!/usr/bin/env perl

# "The structure of PostScript with the quoting horrors of m4."

%a =('df', sub { push @{$d{$s[$#s-1]}}, join ' ', @s[($#s-$s[$#s]-1)..($#s-2)];
		 pop @s for( 1..($s[$#s]+2) ) },
     'ud', sub { pop @{$d{pop @s}} },
     'sl', sub { pop @s },
     'rd', sub { open R, pop @s; e(split) for( <R> ) },
     'pt', sub { print pop @s, "\n" },
     'ex', sub { exit pop @s },
     'gn', sub { $b = 1 },
     'gf', sub { $b = 0 },
     'ps', sub { print "@s\n" },
     'dk', sub { print "$_ => ", ${d{$_}}[$#d], "\n" for( keys %d ) },
     '?',  sub { if( pop @s ) { pop @s; e(pop @s) }
		 else { $q = pop @s; pop @s; e($q) } },
     '+',  sub { push @s, (pop @s) +  (pop @s) },
     '*',  sub { push @s, (pop @s) *  (pop @s) },
     '>',  sub { push @s, (pop @s) <  (pop @s) ? 1 : 0 },
     '<',  sub { push @s, (pop @s) >  (pop @s) ? 1 : 0 },
     '=',  sub { push @s, (pop @s) == (pop @s) ? 1 : 0 },
     '-',  sub { push @s,-(pop @s) } );

sub e { for( @_ ) {
    if(    $b )             { printf "%13s | ", $_; print "@s\n" }
    if(    defined $a{$_} ) { &{$a{$_}} }
    elsif( /\d+/ )          { push @s, $_ }
    elsif( /$\'/ )          { s///; push @s, $_ } #')# stupid emacs
    elsif( defined $d{$_} ) { e(split /\s+/, ${$d{$_}}[$#d]) }
} }

e(split) while( <> );