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Access to keys in EMap member of model element [message #1780744]

Fri, 26 January 2018 14:53

Bruce Trask

Messages: 58
Registered: July 2009

Member

Hello,

I used the steps from
https://wiki.eclipse.org/EMF/FAQ#How_do_I_create_a_Map_in_EMF.3F
to create a map in one of my model elements. It ends up generating an EMap.

My question is how to access that and the keys and values of its elements via the OCL or from the .mtl file in Acceleo.

In the OCL Interpreter view I enter

aql:self.theSystem.services.nameToPackageName // nameToPackageName is the map

as the expression

and I get back

one->two
three->four

which is what the map contains (two key value pairs)

If I do aql:self.theSystem.services.nameToPackageName->asSequence()
I get the same result.

What I am trying to do is iterate through the map to get the individual keys and values.
->at() does not seem to do the trick with the Map.

I was hoping for something like ->get(key) but that does not appear to exist.

I could not find anything with regard to working with Maps in aql or OCL.

Regards,
Bruce

[Updated on: Fri, 26 January 2018 14:56]

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Re: Access to keys in EMap member of model element [message #1780757 is a reply to message #1780744]

Fri, 26 January 2018 16:35

Ed Willink

Messages: 7635
Registered: July 2009

Senior Member

Hi

(The new Pivot-based OCL adds a Map class to the OCL Standard Library; it has an at() operation. Unfortunately Acceleo has not migrated to exploit the new Pivot OCL.)

I have tried occasionally to exploit EMap without success. You may see my most recent attempt in https://bugs.eclipse.org/bugs/show_bug.cgi?id=443021

Since EMap is actually a linear list, you won't see the speedups for large Maps that you might expect, but for small maps the list can be faster...

If you really want a good Map I suggest you hand code the map in your *Impl.java with friendly accessor methods.

Regards

Ed Willink

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