Itearating over Collection in OCL/AQL

Question

Hello all,

I have encountered  following observation related o OCL/AQL

My goal was to simply create a result accumulated over the Collection.

In JS one can use reduce in Arrays, or join on Arrays/String to create accumulated value

For a demo purpose just using simple example ( emulate join(delim) in OCL/AQL)

Sequence of strings -> single string

Now I have played around with the OCL statements inside of the OCL console and compare the evaluation results for derived profile properties ( OCL/AQL)

let source:Sequence(String)=Sequence{'a','bcd','h'}
in 
source->asSet()->iterate(curr:String;acc:String=''| acc+curr+'('+source->indexOf(curr).toString()+'),')
OCL Console:
>>'a(1),bcd(2),h(3),'
OCL Derived Property:
>>Status ERROR: de.ikv.medini.evaluation.engine.mdtocl code=4 Can not evaluate script java.lang.NullPointerException: Cannot invoke "java.lang.Class.getMethod(String, java.lang.Class[])" because "containerClass" is null
AQL Derived Property:
>>false

for some reason the OCL property has some issues with usage source->indexOf(..) and AQL does not return anything at all instead it returns bollean false

Another use case could be that one would want to limit the precision of number in a derived property.

So lets try to do this using toString().tokenize('.') some native supported methods

let proc:Sequence(String)=10.253215151515151.toString().tokenize('.'),
places:Integer=3

in
proc->first()+'.'+proc->last().substring(1,if proc->last().size() > places then Sequence{1,places}->max() else proc->last().size() endif )
OCL Concosle:
>> 10.235
OLC property:
>>10.253
AQL (reqriting neeed due to missing ->max() service, using AQL's number.max(number)
proc->first()+'.'+proc->last().substring(1,if proc->last().size() > places then 1,max(places) else proc->last().size() endif )
>>10.253

PS: for AQL the code needed to be rewritten, because the Collection->max() does no exists in AQL (available number.max(number)

My questions:

* Any idea why the there was a Error raised in OCL property linked to the source->indexOf(),  can you confirm you can see the same ?
* Is there any other alternative in AQL to OCL's ->iterate()
* Would it be possible to extend the Collection by ->iterate()service? 
( I think only for AQL evaluation engine used in profile properties/AQL evaluations inside of scripts

I think the iterate can be useful when it comes to accumulating some result out of Collection( string, number ,... )

PS2: All tested on 25R1

Thanks,

Marian

medini_1063548292 · Answer

Hi Jan,

Let me explain the part about "hidden" service. The remark was related to the fact that in linked Acceleo AQL documentation does not mention the closure service for the collection while the Acceleo plugin has it implemented and available in AQL engine used by m2doc as well as medini profile property ( I tested & confirmed) that it works/

I did a bit of digging , visited the GitHub and explored the documentation. I spotted that the closure  is mentioned. So it is just which documentation is referenced for the AQL

So by this missing docu info I was hoping that same will be valid for iterate  and that it will be inherited/implemented from an OCL.  just not part of the documentation:)

But I learned that for some reason the iterate ( form OCL) is not supported  as a native Collection service. I recall seeing some web page with AQL OCL migration Guidelines  and the iterate was marked as inherited from OCL, but unfortunately i could not find back the page but only found one related  inquiry in  eclipse community forum.Eclipse Community Forums: M2T (model-to-text transformation) » [Acceleo] Strange behavior for queries using the "iterate" method

Anyway not really sure whether all of this the same AQL. and in the end the iterate is giving a "false" as an output.

I alse created a testing m2doc file using simple iterate and also dumping some of the available collection services ( attached docx)

Marian

medini_1024169437 · Answer

Marian, I did not understand the last part, you mean, some functions are available in m2doc but not pure AQL?

Also: closure is available and you got it working?

Maybe we can raise an issue in the m2doc github.

Jan

medini_1063548292 · Answer

Hi Jan,

Thanks for confirmation on the the OCL property output! Bad news that I do recall to observe similar errors in the past but for  different OCL statement constructs, need to recall and probably will create a ticket to follow-up ?

Regarding AQL I was hoping it is somewhat hidden to the user as in case of closure where the official documentation on Acceleo AQL does no mention "->closure" at all while it is available in the Acceleo plugin .. ( snapshot form m2doc interpreter View back from 23R2).

Thanks for confirming that this is a warning resulting in a false as the AQL eval result. So it seems like the AQL plugin does not natively support the OCL iterate, which menas it would only be possible through custom service, might be problematic for performance:(

PS: any chance in the future to integrate some available AQL interpreter similar to what was part of m2doc  ??

Marian