/*

 * Copyright (c) 2005, 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.

 */

/*

 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved

 *

 * The original version of this source code and documentation

 * is copyrighted and owned by Taligent, Inc., a wholly-owned

 * subsidiary of IBM. These materials are provided under terms

 * of a License Agreement between Taligent and Sun. This technology

 * is protected by multiple US and International patents.

 *

 * This notice and attribution to Taligent may not be removed.

 * Taligent is a registered trademark of Taligent, Inc.

 *

 */

package sun.util.resources;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.ResourceBundle;

import java.util.Set;

import sun.util.ResourceBundleEnumeration;

/**

 * Subclass of <code>ResourceBundle</code> which mimics

 * <code>ListResourceBundle</code>, but provides more hooks

 * for specialized subclass behavior. For general description,

 * see {@link java.util.ListResourceBundle}.

 * <p>

 * This class leaves handleGetObject non-final, and

 * adds a method createMap which allows subclasses to

 * use specialized Map implementations.

 */

public abstract class OpenListResourceBundle extends ResourceBundle {

    /**

     * Sole constructor.  (For invocation by subclass constructors, typically

     * implicit.)

     */

    protected OpenListResourceBundle() {

    }

    // Implements java.util.ResourceBundle.handleGetObject; inherits javadoc specification.

    @Override

    protected Object handleGetObject(String key) {

        if (key == null) {

            throw new NullPointerException();

        }

        loadLookupTablesIfNecessary();

        return lookup.get(key); // this class ignores locales

    }

    /**

     * Implementation of ResourceBundle.getKeys.

     */

    @Override

    public Enumeration<String> getKeys() {

        ResourceBundle parentBundle = this.parent;

        return new ResourceBundleEnumeration(handleKeySet(),

                (parentBundle != null) ? parentBundle.getKeys() : null);

     }

    /**

     * Returns a set of keys provided in this resource bundle,

     * including no parents.

     */

    @Override

    protected Set<String> handleKeySet() {

        loadLookupTablesIfNecessary();

        return lookup.keySet();

    }

    @Override

    public Set<String> keySet() {

        if (keyset != null) {

            return keyset;

        }

        Set<String> ks = createSet();

        ks.addAll(handleKeySet());

        if (parent != null) {

            ks.addAll(parent.keySet());

        }

        synchronized (this) {

            if (keyset == null) {

                keyset = ks;

            }

        }

        return keyset;

    }

    /**

     * See ListResourceBundle class description.

     */

    abstract protected Object[][] getContents();

    /**

     * Load lookup tables if they haven't been loaded already.

     */

    void loadLookupTablesIfNecessary() {

        if (lookup == null) {

            loadLookup();

        }

    }

    /**

     * We lazily load the lookup hashtable.  This function does the

     * loading.

     */

    private void loadLookup() {

        Object[][] contents = getContents();

        Map<String, Object> temp = createMap(contents.length);

        for (int i = 0; i < contents.length; ++i) {

            // key must be non-null String, value must be non-null

            String key = (String) contents[i][0];

            Object value = contents[i][1];

            if (key == null || value == null) {

                throw new NullPointerException();

            }

            temp.put(key, value);

        }

        synchronized (this) {

            if (lookup == null) {

                lookup = temp;

            }

        }

    }

    /**

     * Lets subclasses provide specialized Map implementations.

     * Default uses HashMap.

     */

    protected <K, V> Map<K, V> createMap(int size) {

        return new HashMap<>(size);

    }

    protected <E> Set<E> createSet() {

        return new HashSet<>();

    }

    private volatile Map<String, Object> lookup = null;

    private volatile Set<String> keyset;

}