src/java.base/share/classes/sun/reflect/generics/repository/FieldRepository.java

/*
 * Copyright (c) 2003, 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 java.lang.reflect.Type;
import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.tree.TypeSignature;
import sun.reflect.generics.parser.SignatureParser;
import sun.reflect.generics.visitor.Reifier;



/**
 * This class represents the generic type information for a constructor.
 * 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 FieldRepository extends AbstractRepository<TypeSignature> {

    /** The generic type info.  Lazily initialized. */
    private volatile Type genericType;

 // protected, to enforce use of static factory yet allow subclassing
    protected FieldRepository(String rawSig, GenericsFactory f) {
      super(rawSig, f);
    }

    protected TypeSignature parse(String s) {
        return SignatureParser.make().parseTypeSig(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 {@code FieldRepository} that manages the generic type
     * information represented in the signature {@code rawSig}
     */
    public static FieldRepository make(String rawSig, GenericsFactory f) {
        return new FieldRepository(rawSig, f);
    }

 /*
 * 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, which is created by feeding it the factory
 * with which the repository was created.
 */

    public Type getGenericType() {
        Type value = genericType;
        if (value == null) {
            value = computeGenericType();
            genericType = value;
        }
        return value;
    }

    private Type computeGenericType() {
        Reifier r = getReifier();       // obtain visitor
        getTree().accept(r);            // reify subtree
        return r.getResult();           // extract result from visitor
    }
}