ldap/src/main/java/org/apache/directory/shared/ldap/util/PreferencesDictionary.java

/*
 *  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.directory.shared.ldap.util;


import java.util.Dictionary;
import java.util.Enumeration;
import java.util.prefs.Preferences;
import java.util.prefs.BackingStoreException;

import org.apache.commons.lang.exception.NestableRuntimeException;
import org.apache.directory.shared.i18n.I18n;


/**
 * A wrapper around Preferences to access it as a Dictionary.
 * 
 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
 * @version $Rev$
 */
public class PreferencesDictionary extends Dictionary<String,String>
{
    /** the underlying wrapped preferences object */
    private final Preferences prefs;


    // ------------------------------------------------------------------------
    // C O N S T R U C T O R
    // ------------------------------------------------------------------------

    public PreferencesDictionary(Preferences prefs)
    {
        this.prefs = prefs;
    }


    // ------------------------------------------------------------------------
    // E X T R A M E T H O D S
    // ------------------------------------------------------------------------

    /**
     * Gets the Preferences used as the backing store for this Dictionary.
     * 
     * @return the underlying Preferences object
     */
    public Preferences getPreferences()
    {
        return prefs;
    }


    // ------------------------------------------------------------------------
    // D I C T I O N A R Y M E T H O D S
    // ------------------------------------------------------------------------

    public int size()
    {
        try
        {
            return prefs.keys().length;
        }
        catch ( BackingStoreException e )
        {
            throw new NestableRuntimeException( I18n.err( I18n.ERR_04423 ), e );
        }
    }


    public boolean isEmpty()
    {
        try
        {
            return prefs.keys().length == 0;
        }
        catch ( BackingStoreException e )
        {
            throw new NestableRuntimeException( I18n.err( I18n.ERR_04423 ), e );
        }
    }


    @SuppressWarnings("unchecked")
    public Enumeration<String> elements()
    {
        try
        {
            return new ArrayEnumeration( prefs.keys() )
            {
                public String nextElement()
                {
                    String key = ( String ) super.nextElement();

                    return prefs.get( key, null );
                }
            };
        }
        catch ( BackingStoreException e )
        {
            throw new NestableRuntimeException( I18n.err( I18n.ERR_04423 ), e );
        }
    }


    @SuppressWarnings("unchecked")
    public Enumeration<String> keys()
    {
        try
        {
            return new ArrayEnumeration( prefs.keys() );
        }
        catch ( BackingStoreException e )
        {
            throw new NestableRuntimeException( I18n.err( I18n.ERR_04423 ), e );
        }
    }


    public String get( Object key )
    {
        if ( key instanceof String )
        {
            return prefs.get( ( String ) key, null );
        }

        return prefs.get( key.toString(), null );
    }


    public String remove( Object key )
    {
        String retval = get( key );

        if ( key instanceof String )
        {
            prefs.remove( ( String ) key );
        }
        else
        {
            prefs.remove( key.toString() );
        }

        return retval;
    }


    public String put( String key, String value )
    {
        String retval = get( key );

        prefs.put( key, value );

        return retval;
    }
}