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Cast of an IEObjectDescription object [message #1053580]

Mon, 06 May 2013 11:22

Eclipse User

I've been digging into the forum and I couldn't find anything about the issue I'm gonna explain. Here it's:

I'm writing a proposal provider for an element of my grammar (let's say element of type T and attribute attr). The idea is that when someone presses CTRL + SPACE the list to be show should be filtered according to certain logic. The following code shows how I'm retrieving the default information to be displayed by the proposal provider:

//Method
@Override
public void completeT_Attr(EObject model, Assignment assignment, ContentAssistContext context, ICompletionProposalAcceptor acceptor) {

		IScope scope = provider.getScope(model, MyDSLPackage.eINSTANCE.getAttr());

		EClass ec = null;
		QualifiedName nameElemQN = null;
		ICompletionProposal completionProposal = null;
		
		for (IEObjectDescription element : scope.getAllElements()) {

			/*
			* What should I use to cast the element object
			* to an object of a typed defined in my grammar??
			MyTypeOfInterest obj = (MyTypeOfInterest)element.XXXXX;
			*/

		}
}

Can anyone tell me how should I proceed to make the cast work? Is it the right approach to customize a proposal provider where the information to be displayed by the proposal provided comes from different files?

Thanks for your help.

-Alfredo.

Re: Cast of an IEObjectDescription object [message #1053584 is a reply to message #1053580]

Mon, 06 May 2013 11:33

Eclipse User

Hi,

and IEObjectDescription has a EObjectOrProxy that contains the object.
please note: the resolution of the proxy might be expensive.

~Christian

Re: Cast of an IEObjectDescription object [message #1053596 is a reply to message #1053584]

Mon, 06 May 2013 12:25

Eclipse User

Hi Christian,

Thanks for the quick answer.
The method EObjectOrProxy works fine. The problem is that when the object is not defined within the same model where the proposal provider is requested I cannot ask for the container of such as object. In other words, what I meant is that in the following code:

EObject eobj = element.getEObjectOrProxy();
 if(eobj instanceof MyType)
	if(eobj.eContainer() instanceof MyType2)

the method call "eobj.eContainer()" returns null when eobj is not placed within the same file from where I request the provider. Hope it's clear.

Re: Cast of an IEObjectDescription object [message #1053597 is a reply to message #1053596]

Mon, 06 May 2013 12:29

Eclipse User

As i said, you may have to resolve the proxy (Ecoreutil is your friend)

Re: Cast of an IEObjectDescription object [message #1053600 is a reply to message #1053580]

Mon, 06 May 2013 12:41

Eclipse User

You cannot simply cast, the IEObjectDescription is metadata and a
reference to the object. If you resolve the reference in
IEObjectDescription the referenced model will need to be loaded (parsed
etc.) and you may end up with lots of data in memory.

You should try to use the data that is already available in the
IEObjectDescription, and if that is not enough add the metadata that you
need in the logic that produces the IEObjectDescriptions (since when
that is done, the model is instantiated and available without extra cost).

Last resort is to load the model given the URI in the IEObjectDescription.

Hope that helps.

- henrik

On 2013-06-05 17:30, Alfredo Capozucca wrote:
> I've been digging into the forum and I couldn't find anything about the
> issue I'm gonna explain. Here it's:
>
> I'm writing a proposal provider for an element of my grammar (let's say
> element of type T and attribute attr). The idea is that when someone
> presses CTRL + SPACE the list to be show should be filtered according to
> certain logic. The following code shows how I'm retrieving the default
> information to be displayed by the proposal provider:
>
>
> //Method
> @Override
> public void completeT_Attr(EObject model, Assignment assignment,
> ContentAssistContext context, ICompletionProposalAcceptor acceptor) {
>
> IScope scope = provider.getScope(model,
> MyDSLPackage.eINSTANCE.getAttr());
>
> EClass ec = null;
> QualifiedName nameElemQN = null;
> ICompletionProposal completionProposal = null;
>
> for (IEObjectDescription element : scope.getAllElements()) {
>
> /*
> * What should I use to cast the element object
> * to an object of a typed defined in my grammar??
> MyTypeOfInterest obj = (MyTypeOfInterest)element.XXXXX;
> */
>
> }
> }
>
>
>
> Can anyone tell me how should I proceed to make the cast work? Is it the
> right approach to customize a proposal provider where the information to
> be displayed by the proposal provided comes from different files?
>
> Thanks for your help.
>
> -Alfredo.
>
>
>
>

Re: Cast of an IEObjectDescription object [message #1053655 is a reply to message #1053597]

Tue, 07 May 2013 03:36

Eclipse User

Can anyone post an example/link/tip about how to resolve the proxy using Ecore? It'd be very appreciated. Thanks.

Re: Cast of an IEObjectDescription object [message #1053663 is a reply to message #1053655]

Tue, 07 May 2013 04:08

Eclipse User

Hi,

????????

EcoreUtil.resolve(theProxy, theContext)

but as said by me and hendrik: DO NOT DO THAT!

Re: Cast of an IEObjectDescription object [message #1053668 is a reply to message #1053663]

Tue, 07 May 2013 04:15

Eclipse User

If I shouldn't do that, what are the alternatives then? The information available in the IEObjectDescription object is not sufficient to achieve what I want.

Re: Cast of an IEObjectDescription object [message #1053670 is a reply to message #1053668]

Tue, 07 May 2013 04:22

Eclipse User

HI,

you can customize the DefaultResourceDEscriptionStrategy to add user data to the Description

Re: Cast of an IEObjectDescription object [message #1053831 is a reply to message #1053663]

Tue, 07 May 2013 15:10

Eclipse User

On 05/07/2013 10:08 AM, Christian Dietrich wrote:
> Hi,
>
> ????????
>
> EcoreUtil.resolve(theProxy, theContext)
>
> but as said by me and hendrik: DO NOT DO THAT!

sorry if I use this thread but I sometimes cast the eEObjectOrProxy
stored in the IEObjectDescription in the proposal provider because I
know it is NOT a proxy: in my custom scope provider I have to traverse
the model anyway to build the scope correctly, thus the object
descriptions actually contain objects (not proxies). I guess this is
admissible, isn't it?

Lorenzo

--
Lorenzo Bettini, PhD in Computer Science, DI, Univ. Torino
HOME: http://www.lorenzobettini.it

Re: Cast of an IEObjectDescription object [message #1053832 is a reply to message #1053831]

Tue, 07 May 2013 15:19

Eclipse User

yes it depends on if the objects are local or not

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