#!/usr/bin/perl

# make_parser.pl

use strict;
use warnings;

use Parse::RecDescent ();

my $grammar = <<'__EOI__';

   parse : expr eof           { $item[1]                            }

   eof   : /^\Z/

   expr  : expr_(s?) term     { [ (map{@$_}@{$item[1]}), $item[2] ] }

   expr_ : term binop         { [ $item[1], $item[2]              ] }

   term  : unary term         { [ $item[1], $item[2]              ] }
         | /"[^"]*"\[MESH\]/  { [ 'MESH',   $item[1]              ] }
         | '(' expr ')'       { [ 'PAREN',  $item[2]              ] }

   binop : 'OR'               { $item[1]                            }
         | 'AND'              { $item[1]                            }
         | 'NOT'              { $item[1]                            }

#   unary : 'NOT'              { $item[1]                            }
# I don't know what to do with it,
# so I'm not supporting it.
   unary : { undef }

__EOI__

$::RD_HINT  = 1;
# $::RD_TRACE = 1;

rename('MeshGrammar.pm', 'MeshGrammar.pm.bak');

Parse::RecDescent->Precompile($grammar, 'MeshGrammar')
or die("Bad grammar.\n");