The following is my test code (variable grammar is incomplete, everything is compared to 'h'):

use Parse::RecDescent;
use strict;
use warnings;

my $grammar = qq~
   RecTest: ExpSet(s) ( Expression | SubExp )
          | Expression
          | SubExp
          | <error>

   Expression: ELEMENT COMPARE ELEMENT

   ExpSet: ( Expression | SubExp ) JOIN

   SubExp: '(' (ExpSet(s) Expression | Expression) ')'


   ELEMENT: 'h'

   COMPARE: /(?:=(?![><]=))?[><]=?/
          | '!='
          | '='


   JOIN: /and/i
       | /or/i
       | /xor/i


~;

my $parser = new Parse::RecDescent($grammar) or die;
print $parser->RecTest('(h = h and h != h) and ((h > h or h < h') or d
+ie;
[download]

When I run this, it prints out ')', which is not entirely useful but implies that it is succeeding, I think... The problem is, it should NOT be succeeding with those arguments because the parentheses are unbalanced, so I assume I made some mistake, but I don't really understand the syntax well enough to know where. Also, I'm having a hard time figuring out how to do anything with what it attempts to parse (so I can actually evaluate what they want and determine if it occurs on any given day).

Perhaps I'm going about this wrong, if so, I'm open to other ideas. Thanks for any help or advice you can give.

Note: This is my first time even seriously looking at Parse::RecDescent.

---

My code doesn't have bugs, it just develops random features.

Flame ~ Lead Programmer: GMS (DOWN) | GMS (DOWN)