functionDecl: "def" "Operation" name=ID
('(' (params+=EClassParameter (',' params+=EClassParameter)*)? ')' )? "{"

"}"
;

def operation o1(EClass Test){}

grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

Model:{Model}
classes+=(
EClassO
)*
|
("Library" "{"
functions+=functionDecl*
"}")
;
EClassO:
(aEClass|
DS='like' eClass=[ecore::EClass]
);

aEClass: "a" a=_EClass;
_EClass returns ecore::EClass:"EClass" name=ID;

functionDecl: "def" "Operation" name=ID
('(' (params+=EClassParameter (',' params+=EClassParameter)*)? ')' )? "{"

"}"
;

EClassParameter returns ecore::EClass: "EClass" name=ID ;

Library {
	def Operation xxx (EClass A){
	}
}

like A

public class MyDslQNP extends DefaultDeclarativeQualifiedNameProvider {
	
	public String qualifiedName(EClass c) {
		return c.getName();
	}

}

because the parameter declared as Eclass i don't want to seems to be showed in suggestions...

public class FilteringScope implements IScope {

	private IScope delegate;
	private Predicate<IEObjectDescription> filter;

	public FilteringScope(IScope delegate, Predicate<IEObjectDescription> filter) {
		this.delegate = delegate;
		this.filter = filter;
	}

	public IScope getOuterScope() {
		return new FilteringScope(delegate.getOuterScope(), filter);
	}

	public Iterable<IEObjectDescription> getContents() {
		return filter(delegate.getContents());
	}

	public Iterable<IEObjectDescription> getAllContents() {
		return filter(delegate.getAllContents());
	}

	public IEObjectDescription getContentByName(String name) {
		return filter(delegate.getContentByName(name));
	}

	public IEObjectDescription getContentByEObject(EObject object) {
		return filter(delegate.getContentByEObject(object));
	}
	
	public Iterable<IEObjectDescription> getAllContentsByEObject(EObject object) {
		return filter(delegate.getAllContentsByEObject(object));
	}

	protected Iterable<IEObjectDescription> filter(
			Iterable<IEObjectDescription> unfiltered) {
		return Iterables.filter(unfiltered, filter);
	}

	protected IEObjectDescription filter(IEObjectDescription contentByEObject) {
		if (!filter.apply(contentByEObject))
			return null;
		return contentByEObject;
	}

	public IScope scope_Ref_theEClass(Ref ref, EReference eReference) {
		IScope delegateScope = delegateGetScope(ref,eReference);
		return new FilteringScope(delegateScope, new Predicate<IEObjectDescription>() {
			@Override
			public boolean apply(IEObjectDescription input) {
				if (...) {
					return false;
				}
				return true;
			}
		});
	}

	public IScope scope_ETypedElement_eType(EAttribute a, EReference r) {
		return Scopes.scopeFor(Iterables.filter(EcorePackage.eINSTANCE.getEClassifiers(),EDataType.class));
	}

CC: xxx=ID ('(' list+=A (',' list+=A)* ')');

A: {A} type=[ecore::EClass];

	public IScope scope_A_type(CC c, EReference r) {
		System.out.println(-1);
		return delegateGetScope(c, r);
	}
	
	public IScope scope_A_type(A a, EReference r) {
		System.out.println(((CC)a.eContainer()).getList().indexOf(a));
		return delegateGetScope(a, r);
	}