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Home » Modeling » TMF (Xtext) » A couple of questions about Scope
A couple of questions about Scope [message #1044398] Thu, 18 April 2013 21:39 Go to next message
Steve Kallestad is currently offline Steve KallestadFriend
Messages: 62
Registered: March 2013
Member
I have a couple of questions about scope. Hopefully they are easy.

The first has to do with getting elements within a given parent.

I'm calling
  ScopeProvider.getScope(parentEObject, MyDSLPackage.eInstance.getChildElements());


I notice that my result set of Child Elements is not limited to those declared under the parentEObject, but in fact are all of the Child Elements contained within the script. They have qualified names, and I can filter them so it's not a huge problem, but I expected the ScopeProvider to return a limited result set, so I'm wondering if I didn't do something wrong.

===============
My next question is about filtering scope for a unique result. I'm looking for a particular eObject by ID or Name.

		IScope scope = sp.getScope(model, MyDSLPackage.eINSTANCE.getMy_Elements());
		Predicate<IEObjectDescription> filter = new Predicate<IEObjectDescription>(){
			public boolean apply(IEObjectDescription input) {
				if (input.getUserData("name").equals(myString) ||
                                    input.getUserData("id").equals(form))){
						return true;
				} else {
					return false;
				}
			};
			
		};
		IScope filtered = new FilteringScope( scope, filter  );


If there are 1000 IEObjectDescriptions to search and the one I'm looking for is the first one, the apply function still continues to process the remaining 999 IEObjectDescriptions. I'm wondering if there is a way to execute an early exit once I find what I'm looking for.

===========

My third question is about indexing/caching of IEObjectDescriptions. I have an expectation of a potentially large amount of imports. I haven't tested a large set just yet, but I'm concerned that if things grow too much the IDE will experience performance problems.

I remember seeing a blog post a while back about implementing an index, but I somehow got the impression that was out-of-the-box now.

Is there a cached index? Or should I look to implement one in my ResourceDescriptionStrategy should the need arise?
Re: A couple of questions about Scope [message #1044613 is a reply to message #1044398] Fri, 19 April 2013 05:59 Go to previous messageGo to next message
Sebastian Zarnekow is currently offline Sebastian ZarnekowFriend
Messages: 2936
Registered: July 2009
Senior Member
Hi,

what do you mean by 'all elements are processed'. When does that happen?
Does it happen if you return 'true' from your filter predicate?
Caching / indexing works behind the scenes but it's possible to screw
that due to wrong assumptions and 'optimizations' in the client code.
As always I suggest to use a profiler before thinking about potential
problems.

Regards,
Sebastian
--
Looking for professional support for Xtext, Xtend or Eclipse Modeling?
Go visit: http://xtext.itemis.com

Am 18.04.13 23:39, schrieb Steve Kallestad:
> I have a couple of questions about scope. Hopefully they are easy.
>
> The first has to do with getting elements within a given parent.
>
> I'm calling
>
> ScopeProvider.getScope(parentEObject,
> MyDSLPackage.eInstance.getChildElements());
>
>
> I notice that my result set of Child Elements is not limited to those
> declared under the parentEObject, but in fact are all of the Child
> Elements contained within the script. They have qualified names, and I
> can filter them so it's not a huge problem, but I expected the
> ScopeProvider to return a limited result set, so I'm wondering if I
> didn't do something wrong.
>
> ===============
> My next question is about filtering scope for a unique result. I'm
> looking for a particular eObject by ID or Name.
>
> IScope scope = sp.getScope(model,
> MyDSLPackage.eINSTANCE.getMy_Elements());
> Predicate<IEObjectDescription> filter = new
> Predicate<IEObjectDescription>(){
> public boolean apply(IEObjectDescription input) {
> if (input.getUserData("name").equals(myString) ||
> input.getUserData("id").equals(form))){
> return true;
> } else {
> return false;
> }
> };
>
> };
> IScope filtered = new FilteringScope( scope, filter );
>
>
> If there are 1000 IEObjectDescriptions to search and the one I'm looking
> for is the first one, the apply function still continues to process the
> remaining 999 IEObjectDescriptions. I'm wondering if there is a way to
> execute an early exit once I find what I'm looking for.
>
> ===========
>
> My third question is about indexing/caching of IEObjectDescriptions. I
> have an expectation of a potentially large amount of imports. I haven't
> tested a large set just yet, but I'm concerned that if things grow too
> much the IDE will experience performance problems.
>
> I remember seeing a blog post a while back about implementing an index,
> but I somehow got the impression that was out-of-the-box now.
>
> Is there a cached index? Or should I look to implement one in my
> ResourceDescriptionStrategy should the need arise?
Re: A couple of questions about Scope [message #1044708 is a reply to message #1044613] Fri, 19 April 2013 08:29 Go to previous message
Steve Kallestad is currently offline Steve KallestadFriend
Messages: 62
Registered: March 2013
Member
Sebastian Zarnekow wrote on Fri, 19 April 2013 01:59
Hi,

what do you mean by 'all elements are processed'. When does that happen?
Does it happen if you return 'true' from your filter predicate?

Regards,
Sebastian
--


Well the short answer is that it was a *me* problem.

I was iterating through the entire filtered scope when I didn't need to.
while (FiltereScopeIterator.hasNext()){
...
} 

instead of just
if(FilterScopeIterator.hasNext()){
    IEObjectDescription firstMatch = FilteredScopeIterator.next();
}

The first question I mentioned (about child elements) I resolved by leveraging NodeModelUtils.findNodesForFeature rather than using the scope provider.

Sometimes it just takes a little bit of time away from the screen for things to make sense.
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