use strict;
use warnings;

use Data::Dumper;
use Parse::RecDescent;
$RD_HINT = 1;

use vars qw(
   %item @item $return
   %symbol %axis
   @code $curr %label
);

@axis{'X','Y','Z'} = (0,0,1);
@code = ();

my $parser = Parse::RecDescent->new(q(
   startrule : opcode | label opcode

   label: /[a-z]\w*/i {
      print "got label: $item[1]\n";
      $main::label{$item[1]} = $#main::code;
   }

   opcode: IF | YMOVE | XMOVE | DOWN |
      UP | PRINTLOC | GOTO |
      SET | ADD | SUB | HALT

   YMOVE: /YMOVE/i int_or_var { 
      push @main::code, [
         sub { $main::axis{Y} += $_[0] }, [$item{int_or_var}],
      ];
   }

   XMOVE: /XMOVE/i int_or_var {
      push @main::code, [
         sub { $main::axis{X} += $_[0] }, [$item{int_or_var}],
      ];
   }

   DOWN: /DOWN/i {
      push @main::code, [ sub { $main::axis{Z}-- },[]];
   }

   UP: /UP/i {
      push @main::code, [ sub { $main::axis{Z}++ },[]];
   }

   PRINTLOC: /PRINTLOC/i {
      push @main::code, [ 
         sub { print "@{[map $main::axis{$_},sort keys %main::axis]}\n" }, [],
      ];
   }

   IF: /IF/i int_or_var relop int_or_var label_name {
      print "got if: @item\n";
   }

   GOTO: /GOTO/i label_name {
      push @main::code, [ 
         sub { $main::curr = $main::label{$item{label_name}} },[]
      ];
   }
   
   SET:      /SET/i var_name int_or_var {
      $main::symbol{$item{var_name}} = $item{int_or_var};
      push @main::code, [ 
         sub   { $main::symbol{$_[0]} = $_[1] },
         [$item{var_name}, $item{int_or_var}],
      ];
   }

   ADD: /ADD/i var_name int_or_var {
      $main::symbol{$item{var_name}} += $item{int_or_var};
      push @main::code, [ 
         sub   { $main::symbol{$_[0]} += $_[1] },
         [$item{var_name}, $item{int_or_var}],
      ];
   }

   SUB: /SUB/i var_name int_or_var {
      $main::symbol{$item{var_name}} -= $item{int_or_var};
      push @main::code, [ 
         sub   { $main::symbol{$_[0]} -= $_[1] },
         [$item{var_name}, $item{int_or_var}],
      ];
   }

   HALT: /HALT/i {
      push @main::code, [ sub { exit(0); },[]];
   }

   label_name: /[a-z]\w*/i

   int_or_var: var_value | int

   var_name: /[a-z]\w*/i
   
   var_value: /[a-z]\w*/i {
      $return = $main::symbol{$item[1]};
   }

   int: /-*\d+/

   relop: '<' | '>' | '==' | '!=' | '>=' | '<='

));

$parser->startrule($_) while <DATA>;

for ($curr = 0; $curr < @code; $curr++) {
   my ($sub,$args) = @{$code[$curr]};
   $sub->(@$args);
}

__DATA__
   YMOVE 10              # along y-axis
   SET RMOVE 0           # sets RMOVE to 0
L1  ADD RMOVE 1          # adds 1 to RMOVE
   xmove 1               # along x-axis
   IF rmove < 8 L1
   IF 9 < 8 L1
YMOVE -3
   down                  # along z-axis (lower gripper)
   PRINTLOC
HALT