[rules-users] Error in OR rule

[Wolfgang Laun]

This is due to a designed or accidental glitch in the LHS syntax.

An "and" CE may not contain an "or" CE as one of its operands; it
may only contain a *parenthesized *"or" (but all other CEs without
the additional decoration). This means that you must write

  (or (and MyFact(id==1)
                MyFact(id==2))
        (    # !
           (or MyFact(id==3) MyFact(id==4))
        )    # !
  )

The simplified version from Piotr's post is, of course, preferred.

Sadly, there is more than one discrepancy between the DRL syntax as
presented in
the non-normative syntax diagrams shown in the Drools Expert manual and the
actual syntax as implemented in the DRL.g file.

-W


2010/5/24 Giovanni Motta <mottagio at gmail.com>

> Hello, i had similar problems with or constructs, and decided to avoid
> them.
> Drools expert manual says that or constructs are internally rewritten, i
> suppose this mechanism is not fine-tuned.
> My 2 cents...
>
> 2010/5/24 Piotr Jedrychowski <pjedrychowski at proximetry.pl>
>
> Hello.
>>
>> I have a problem with such a condition after 'when':
>> (or (and MyFact(id==1) MyFact(id==2)) (or MyFact(id==3) MyFact(id==4)))
>>
>> For this condition I got this error:
>> errors; [7,41]: [ERR 101] Line 7:41 no viable alternative at input 'or'
>> in rule "Sensor-1-ON"[7,64]: [ERR 102] Line 7:64 mismatched input
>> 'MyFact' expecting ')' in rule "Sensor-1-ON"[7,84]: [ERR 102] Line 7:84
>> mismatched input ')' expecting 'then' in rule "Sensor-1-ON"
>>
>> When I changed my condition to this:
>> (or (and MyFact(id==1) MyFact(id==2)) MyFact(id==3) MyFact(id==4))
>> everything is correct. Both conditions from logic point of view, are the
>> same, but the first one can't be compiled. Why?
>>
>> Maybe someone had similar problem and could help me?
>>
>> I'm using:
>> * JBoss 4.2.3.GA
>> * Drools 5.0
>>
>> Regards,
>> Piotr
>> _______________________________________________
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>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
>
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