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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * 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 {@code D} represents the type of reflective

 * object whose scope this class is representing.

 * <p> To subclass this, all one needs to do is implement

 * {@code computeEnclosingScope} and the subclass' constructor.

 */

public abstract class AbstractScope<D extends GenericDeclaration>

    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 {@code Scope}

     * object represents.

     * @return The object whose scope this {@code 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 value = enclosingScope;

        if (value == null) {

            value = computeEnclosingScope();

            enclosingScope = value;

        }

        return value;

    }

    /**

     * 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);

    }

}