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

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

And if you wanted 'and' to be higher precedence than 'or' and 'xor', so as not to confuse the rest of us:

expression: <leftop: term termop term>
termop: 'or' | 'xor'
term: <leftop: factor factorop factor>
factorop: 'and'
factor: '(' expression ')' | condition
condition: field comparison value
field: '<' timethingy '>'
timethingy: 'DAY' | 'WEEK'
comparison: '<=' | '<' | '=' | '>=' | '>' | '!='
value: /\d+/
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-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Note: Before I start, I have noticed your other suggestion, however this is based off of this code.

Well, I've modified your suggestion a little, and assuming I understood your suggestion's intent, I seem to have screwed it up somewhere along the line, because it still does not handle ( ) properly, but I can't see why. This is what I now have:

use Parse::RecDescent;
use Data::Dumper;
use strict;
use warnings;

$::RD_TRACE = 1;


my $grammar = q~

   expression: <leftop: term termop term> eod

   termop: /and/i | /xor/i | /or/i

   term: '(' <commit> expression ')' | condition

   condition: element comparison element

   element: '<' <commit> /-?\w+/ '>'
          | /\d+/

   comparison: /=[><]=/ <commit> <error: Unable to match comparison>
             | /=?[><]=?/
             | '='
             | '!='

   eod: /^\Z/

~;

my $parser = new Parse::RecDescent($grammar) or die;
#defined($parser->RecTest('h =>= h')) or die;

my $test = '(<MONTH> => <DAY>)'; # or (<MONTH> = <MARCH> and <DAY> = <
+TUESDAY>)';

print Dumper($parser->expression($test));
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I repeatedly get "$VAR1 = undef;" in reply, as well as enough debugging info to scroll off my screen (unfortunately I can't capture it into a file either, Parse::RecDescent overrides any re-declarations on STDERR, and I can't use "perl language.pl | more" or any other similar methods since those don't want to capture the error messages...) Anyone see what I'm missing, it's probably obvious, but I've been staring at it for 4 hours now without anything more constructive happening than the condensing of a few rules in the grammar declaration.

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

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

Flame feels rediculously stupid.

Ok, found THAT problem. The "eod" rule at the end of "expression", was being called upon whenever expression was used, meaning that the ')' had to somehow come after the end of the data. With that fixed, I need to do a few more tests, but this is how it looks NOW:

my $grammar = q~

   logic: expression eod

   expression: <leftop: term termop term>

   termop: /and/i | /xor/i | /or/i

   term: '(' <commit> expression ')' | condition

   condition: element comparison element

   element: '<' <commit> /-?\w+/ '>'
          | /\d+/

   comparison: /=[><]=/ <commit> <error: Unable to match comparison>
             | /=?[><]=?/
             | '='
             | '!='

   eod: /^\Z/

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

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