[rules-users] using complex evaluate expressions with DSL

[maverik j]

Here is the complete DSL/DSLR

DSLr:
rule "Your First Rule"
 when
    There is a Department
    There is at least one Person
    - with a valid subOrdinate
    - check that name follows pattern "M"
then
   >System.out.println("Test Generic Cosntranit done !!!");
end

DSL:
[keyword][]check that {conditions}= eval( {conditions} )
[keyword][]AND = &&
[keyword][]OR  = ||
[when][][Tt]here is an? {entity}= {entity}: {entity}()
[when][][Tt]here is at least one {entity}= exists {entity}: {entity}()
[when][]the {entity:\w+}'s {attr:\w+} = {entity}.get{attr}()
[when][]- with {attr} equal to {value} = {attr} == {value}
[when][]- with a valid {attr} = {attr} != null
[when][]- with {attr} not equal to {value} = {attr} != {value}
[when][]- eval\( {whatever} \)= eval( {whatever} )
[when][] {attr} equals {value} = {attr}.equals({value})
[when][] {attr} is valid  =  {attr} != null
[when][] {attr} follows pattern {x} =  startsWithFunction({attr},{x})

Function used in drl is:
function boolean startsWithFunction(String value, String beginning) {
 if (value == null) return false;
 if (beginning == null) return false;
 return value.startsWith(beginning);
}
I am using drools version 5.1.1

Thanks & Regards,
-Maverik

2011/1/4 Wolfgang Laun <wolfgang.laun at gmail.com>

> Do you have any comments ("#..." or "//...") between when and then? If so,
> please remove and try again.
>
> If this doesn't fix it, please post completely and exactly
> - the rule from the DSLR
> - the full DSL
> - Drools version.
>
> Thanks
> -W
>
>
>
>
> 2011/1/4 maverik j <maverikj348 at gmail.com>
>
>>
>>
>> 2011/1/4 Wolfgang Laun <wolfgang.laun at gmail.com>
>>
>>
>>>
>>> 2011/1/4 maverik j <maverikj348 at gmail.com>
>>>
>>>  is there any restriction in terms of using custom function in condition
>>>> etc.
>>>> If I add function evaluation to conditions its messing up with dsl. For
>>>> pattern matching if I use custom function defined in drl then its not able
>>>> to parse that properly
>>>>
>>>> [when][] {attr:\S+} follows pattern {pattern:\S+} =
>>>> funcToEvalPattern({attr},( {pattern} )
>>>>
>>>
>>> Is this exactly what you have in the DSL definition? It's syntactically
>>> incorrect.
>>>
>>
>>
>>>   Sorry for that, it is actually
>>>
>>
>>
>>>  [when][] {*attr*} follows pattern {pattern} = startsWithFunction( {*
>>> attr*}, {pattern} )
>>>>
>>>>  and is being added as last statement in DSL (for testing purpose I am
>>>> using same dsl as you have shown)
>>>>
>>>
>>
>>>    in this case it is getting translated to
>>>> exists(Person:Person(subordinate != null , startsWithFunction( *eval*(
>>>> name, "I" ) ) )
>>>>  where as I was hoping this to be
>>>> exists(Person:Person(subordinate != null , *eval *(startsWithFunction(
>>>> name, "I" ) ) )
>>>>
>>>>
>>>
>>> I cannot reproduce this. But it may depend on the order of your entries
>>> in you DSL file.
>>>
>>> Actually I tried changing order as well but didnt worked. I have actually
>> defined these common functions in drl and added that to knowledgebase along
>> with these DSL and DSLR.
>>
>>
>>
>>>  -W
>>>
>>>
>>>
>>>> Regards,
>>>> -Maverik
>>>>
>>>> On Tue, Jan 4, 2011 at 12:24 PM, maverik j <maverikj348 at gmail.com>wrote:
>>>>
>>>>> cool...this was of great help, I will try this out I think it shoudl
>>>>> solve the purpose.
>>>>>
>>>>> Thanks once again,
>>>>> Maverik
>>>>>
>>>>> 2011/1/3 Wolfgang Laun <wolfgang.laun at gmail.com>
>>>>>
>>>>> Try using eval as a last resort. A better (smaller, more robust) DSL
>>>>>> can be designed around facts and their attributes.
>>>>>>
>>>>>> "||" (and "OR") can be used, but setting parentheses in order to get
>>>>>> the priority right is difficult. In constraints, you may have to resort to
>>>>>> "memberof" or "not memberof".
>>>>>>
>>>>>> Your sample isn't self-contained. But I think that the following DSL
>>>>>> and the DSLR might give you some ideas how to proceed.
>>>>>>
>>>>>> [keyword][]check that {conditions}= eval( {conditions} )
>>>>>> [keyword][]AND = &&
>>>>>> [keyword][]OR  = ||
>>>>>>
>>>>>> [when][][Tt]here is an? {entity}= {entity}: {entity}()
>>>>>> [when][][Tt]here is at least one {entity}= exists {entity}: {entity}()
>>>>>>
>>>>>> [when][]the {entity:\w+}'s {attr:\w+} = {entity}.get{attr}()
>>>>>>
>>>>>> [when][]- with a valid {attr} = {attr}: {attr} != null
>>>>>> [when][]- with {attr} not equal to {value} = {attr} != {value}
>>>>>> [when][]- eval\( {whatever} \)=eval( {whatever} )
>>>>>>
>>>>>> [when][] {attr:\S+} follows pattern {pattern:\S+} =  {attr}.matches(
>>>>>> {pattern} )
>>>>>> [when][] {attr:\S+} not equals? {value:\S+} = ! {attr}.equals( {value}
>>>>>> )
>>>>>> [when][] {attr:\S+} is valid  =  {attr} != null
>>>>>>
>>>>>> rule "Rule 5"
>>>>>> when
>>>>>>     There is a Department
>>>>>>     There is at least one Person
>>>>>>     - with name not equal to "xxx"
>>>>>>     - with a valid subordinate
>>>>>>     - check that the Person's Id is valid AND the Department's Id
>>>>>> follows pattern "I" AND the Department's HeadOfDpt not equal name
>>>>>> then
>>>>>> end
>>>>>>
>>>>>> Notice that "-check that..." must be written as a single line.
>>>>>>
>>>>>> -W
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> 2011/1/3 maverik j <maverikj348 at gmail.com>
>>>>>>
>>>>>>>   Hi,
>>>>>>>
>>>>>>>  We are planning to use DSL/DSRL approach with generic DSL template
>>>>>>> like say
>>>>>>>
>>>>>>> [condition][]The {object} has valid {field}={object}({field} != null
>>>>>>> )
>>>>>>>
>>>>>>> [condition][]there is object {*obj*} that = {*obj*}()
>>>>>>>
>>>>>>> [condition][]- has {*attr*} equal {*val*} = {*attr*} == {*val*}
>>>>>>>
>>>>>>> [condition][]- has valid {*attr*} = {*attr*} != null
>>>>>>>
>>>>>>> [condition][]- and has {*attr*} equal {value}= && {*attr*} ==
>>>>>>> {value}
>>>>>>>
>>>>>>> But there are quite few of requirements like to have DSL rules that
>>>>>>> can generate expression as follows:
>>>>>>> exists Employee(
>>>>>>>    attribute name not equals "xxx"
>>>>>>>    && the attribute subOrdinate is not null
>>>>>>>    && eval(
>>>>>>>    the attribute $dept.getId() is not null
>>>>>>>    && attribute $dept.getId() follows pattern "I"
>>>>>>>    && ( ! (the attribute $dept.getHeadOfDpt() equals name)
>>>>>>>    )
>>>>>>> )
>>>>>>>
>>>>>>> I am not sure if this is possible with DSL. Using '-' operator we
>>>>>>> cannot really add '&&', '||' conditions it by-default expands to ','
>>>>>>> separated and conditions. And wirtting generic rules with and/or is not
>>>>>>> really dynamic to allow any number of expressions in evaluation.
>>>>>>>
>>>>>>> i am struggling to get this run since long time so any help/thoughts
>>>>>>> on this would be  highly appriciable !!!
>>>>>>>
>>>>>>> Thanks & Regards,
>>>>>>> -Maverik
>>>>>>>
>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>>
>>>>>>
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