/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.xerces.jaxp.validation;

import java.lang.ref.WeakReference;

import org.apache.xerces.xni.grammars.XMLGrammarPool;

/**
 * <p>An implementation of Schema for W3C XML Schemas
 * that keeps a weak reference to its grammar pool. If
 * no validators currently have a reference to the
 * grammar pool, the garbage collector is free to reclaim
 * its memory.</p>
 * 
 * @author Michael Glavassevich, IBM
 * @version $Id: WeakReferenceXMLSchema.java 447235 2006-09-18 05:01:44Z mrglavas $
 */
final class WeakReferenceXMLSchema extends AbstractXMLSchema {
    
    /** Weak reference to grammar pool. */
    private WeakReference fGrammarPool = new WeakReference(null);

    public WeakReferenceXMLSchema() {}
    
    /*
     * XSGrammarPoolContainer methods
     */

    public synchronized XMLGrammarPool getGrammarPool() {
        XMLGrammarPool grammarPool = (XMLGrammarPool) fGrammarPool.get();
        // If there's no grammar pool then either we haven't created one
        // yet or the garbage collector has already cleaned out the previous one. 
        if (grammarPool == null) {
            grammarPool = new SoftReferenceGrammarPool();
            fGrammarPool = new WeakReference(grammarPool);
        }
        return grammarPool;
    }

    public boolean isFullyComposed() {
        return false;
    }

} // WeakReferenceXMLSchema