sun.reflect.generics.scope.AbstractScope Maven / Gradle / Ivy
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* published by the Free Software Foundation. Oracle designates this
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*
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package sun.reflect.generics.scope;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.TypeVariable;
/**
* Abstract superclass for lazy scope objects, used when building
* factories for generic information repositories.
* The type parameter D represents the type of reflective
* object whose scope this class is representing.
* To subclass this, all one needs to do is implement
* computeEnclosingScope and the subclass' constructor.
*/
public abstract class AbstractScope
implements Scope {
private final D recvr; // the declaration whose scope this instance represents
/** The enclosing scope of this scope. Lazily initialized. */
private volatile Scope enclosingScope;
/**
* Constructor. Takes a reflective object whose scope the newly
* constructed instance will represent.
* @param decl - A generic declaration whose scope the newly
* constructed instance will represent
*/
protected AbstractScope(D decl){ recvr = decl;}
/**
* Accessor for the receiver - the object whose scope this Scope
* object represents.
* @return The object whose scope this Scope object represents
*/
protected D getRecvr() {return recvr;}
/** This method must be implemented by any concrete subclass.
* It must return the enclosing scope of this scope. If this scope
* is a top-level scope, an instance of DummyScope must be returned.
* @return The enclosing scope of this scope
*/
protected abstract Scope computeEnclosingScope();
/**
* Accessor for the enclosing scope, which is computed lazily and cached.
* @return the enclosing scope
*/
protected Scope getEnclosingScope(){
Scope enclosingScope = this.enclosingScope;
if (enclosingScope == null) {
enclosingScope = computeEnclosingScope();
this.enclosingScope = enclosingScope;
}
return enclosingScope;
}
/**
* Lookup a type variable in the scope, using its name. Returns null if
* no type variable with this name is declared in this scope or any of its
* surrounding scopes.
* @param name - the name of the type variable being looked up
* @return the requested type variable, if found
*/
public TypeVariable lookup(String name) {
TypeVariable[] tas = getRecvr().getTypeParameters();
for (TypeVariable tv : tas) {
if (tv.getName().equals(name)) {return tv;}
}
return getEnclosingScope().lookup(name);
}
}