Java example source code file (ClassRepository.java)

This example Java source code file (ClassRepository.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classrepository, classsignature, genericdeclrepository, genericsfactory, ljava\/lang\/object, none, reflection, reifier, type, typetree

The ClassRepository.java Java example source code

/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * 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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.reflect.generics.repository;

import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.tree.ClassSignature;
import sun.reflect.generics.tree.TypeTree;
import sun.reflect.generics.visitor.Reifier;
import sun.reflect.generics.parser.SignatureParser;
import java.lang.reflect.Type;


/**
 * This class represents the generic type information for a class.
 * The code is not dependent on a particular reflective implementation.
 * It is designed to be used unchanged by at least core reflection and JDI.
 */
public class ClassRepository extends GenericDeclRepository<ClassSignature> {

    public static final ClassRepository NONE = ClassRepository.make("Ljava/lang/Object;", null);

    private Type superclass; // caches the generic superclass info
    private Type[] superInterfaces; // caches the generic superinterface info

 // private, to enforce use of static factory
    private ClassRepository(String rawSig, GenericsFactory f) {
        super(rawSig, f);
    }

    protected ClassSignature parse(String s) {
        return SignatureParser.make().parseClassSig(s);
    }

    /**
     * Static factory method.
     * @param rawSig - the generic signature of the reflective object
     * that this repository is servicing
     * @param f - a factory that will provide instances of reflective
     * objects when this repository converts its AST
     * @return a <tt>ClassRepository that manages the generic type
     * information represented in the signature <tt>rawSig
     */
    public static ClassRepository make(String rawSig, GenericsFactory f) {
        return new ClassRepository(rawSig, f);
    }

    // public API
 /*
 * When queried for a particular piece of type information, the
 * general pattern is to consult the corresponding cached value.
 * If the corresponding field is non-null, it is returned.
 * If not, it is created lazily. This is done by selecting the appropriate
 * part of the tree and transforming it into a reflective object
 * using a visitor.
 * a visitor, which is created by feeding it the factory
 * with which the repository was created.
 */

    public Type getSuperclass(){
        if (superclass == null) { // lazily initialize superclass
            Reifier r = getReifier(); // obtain visitor
            // Extract superclass subtree from AST and reify
            getTree().getSuperclass().accept(r);
            // extract result from visitor and cache it
            superclass = r.getResult();
            }
        return superclass; // return cached result
    }

    public Type[] getSuperInterfaces(){
        if (superInterfaces == null) { // lazily initialize super interfaces
            // first, extract super interface subtree(s) from AST
            TypeTree[] ts  = getTree().getSuperInterfaces();
            // create array to store reified subtree(s)
            Type[] sis = new Type[ts.length];
            // reify all subtrees
            for (int i = 0; i < ts.length; i++) {
                Reifier r = getReifier(); // obtain visitor
                ts[i].accept(r);// reify subtree
                // extract result from visitor and store it
                sis[i] = r.getResult();
            }
            superInterfaces = sis; // cache overall result
        }
        return superInterfaces.clone(); // return cached result
    }
}