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How to get scope for jvm type or pojo [message #1065188]

Mon, 24 June 2013 16:28

Ian McDevitt

Messages: 70
Registered: December 2012
Location: Belfast

Member

This is a simplified version of what I am trying to do. I declare an object with a type and then use its members in method calls. The DSL could look like this

NEW t1 as java.util.Timer
CALL t1.cancel

but I get an error line under cancel, so I have tried to set the right scope.

I have done this before when the type is a DSL type, it is straight forward to add the operations of the type to the scope as shown in other posts such as http://stackoverflow.com/questions/7791871/xtext-example-of-a-scoped-object.

But when the type is a normal Java class (not created in the DSL) then I am stuck. I believe it can be done as I see it in Xbase but I cannot get it to work as all the methods for working with Scopes seem to require EObjects not Objects.

Here is an example grammar, but I have also tried using feature=XMemberFeatureCall and other Xbase rules without success.

grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.xbase.Xbase
generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
import "http://www.eclipse.org/xtext/common/JavaVMTypes" as types

Model:	elements+=(NewPojo|Operation)*;
	
NewPojo: 'NEW' name=ID 'as' type=JvmTypeReference ;

Operation: 'CALL' target=[NewPojo] '.' feature=[types::JvmIdentifiableElement] ;

I usually get "couldn't resolve reference to JvmIdentifiableElement 'cancel'". I know the 'cancel' method is a JVM operation so I want to set the scope as the members of the type of the target, but I can't see how to get from a Method[] to a list of EObjectDescriptions. Is there a utility?

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Re: How to get scope for jvm type or pojo [message #1065193 is a reply to message #1065188]

Mon, 24 June 2013 17:37

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Hi,

have a look at the class Scopes.

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: How to get scope for jvm type or pojo [message #1065214 is a reply to message #1065193]

Mon, 24 June 2013 19:57

Ian McDevitt

Messages: 70
Registered: December 2012
Location: Belfast

Member

It's funny how it starts working after you ask someone. I find now that getting the contents from the JvmType (from the JvmTypeReference) is now giving me a list of EObjects,

target.type.type.eContents

Somehow I had been getting an empty list every time before. Not sure what I did differently this time but I can now get the methods from the jvm type as EObjects.

I will work with Scopes::scopeFor and others. It is creating a scope list with the methods in it but something else is not working as I still get the error. I have a custom scope_Operation_feature method so I'll debug on a bit more myself now I've got the first problem solved.
Thanks
Ian

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Re: How to get scope for jvm type or pojo [message #1065860 is a reply to message #1065214]

Thu, 27 June 2013 22:31

Ian McDevitt

Messages: 70
Registered: December 2012
Location: Belfast

Member

For anyone with a similar problem, I have got the rest of this working now but not quite as first expected.

In the getScope method of my delegate scope provider, which extends XImportSectionNamespaceScopeProvider, I check that it's looking to scope an OPERATION__FEATURE reference (otherwise I get cyclic exceptions if it's looking for the OPERATION_TARGET) and I get the list of pojo members from the target type as EObjects:

context.target.type.type.eContents.filter(typeof(JvmFeature))

(the first 'type' is a typeRef).

So far so good.

But when I used

Scopes::scopeFor

it gave me an empty scope. This seems to be a result of Scopes::scopedElementsFor producing null qualified names when transforming the EObjects to EObjectDescriptions.

So I did my own transform on the list using

EObjectDescription::create

to get the list as object descriptions and then used

MapBasedScope::createScope

and that did the job nicely.

(edited to replace XbaseImportedNamespaceScopeProvider with XImportSectionNamespaceScopeProvider, as I've recently migrated to 2.4 where it's been deprecated - so now my content assist works again!)

[Updated on: Thu, 27 June 2013 23:08]

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Re: How to get scope for jvm type or pojo [message #1065871 is a reply to message #1065860]

Fri, 28 June 2013 05:04

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Hi please Note that you may have to use the scopefor Method. With namecomputation Since the Method may not have a properste Named name

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: How to get scope for jvm type or pojo [message #1092148 is a reply to message #1065871]

Thu, 22 August 2013 11:44

Eclipse User

Great, EObjectDescription::create worked for my Problem too. Before that, I tried to use the nameComputation Function but didn't succeed under xtend scope provider. Is there any code snippet to solve this under xtend with xtext 2.4.2?

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Re: How to get scope for jvm type or pojo [message #1095983 is a reply to message #1092148]

Tue, 27 August 2013 20:11

Ian McDevitt

Messages: 70
Registered: December 2012
Location: Belfast

Member

I did change to use scopeFor and a name computation, but I also also stopped using the xbase scope provider. I'll see if I can dig out the code to see if it helps any.

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Re: How to get scope for jvm type or pojo [message #1096076 is a reply to message #1095983]

Tue, 27 August 2013 23:44

Ian McDevitt

Messages: 70
Registered: December 2012
Location: Belfast

Member

This was what I had at the time as an example of using a trivial naming function in the scope function to get elements from a JvmTypeReference. It was mainly to help me understand how things were working rather than best practice but it may point you to something in your own code.

var Function<JvmFeature, QualifiedName> getNameOfJvmFeature = [ QualifiedName::create(it.simpleName) ]
val jvmFeatures = aTypeRef.type.eContents.filter(typeof(JvmFeature))
scope = Scopes::scopeFor(jvmFeatures, getNameOfJvmImplFeature, scope)

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