    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.configuration2;
    019
    020import java.util.AbstractMap;
    021import java.util.AbstractSet;
    022import java.util.Iterator;
    023import java.util.Map;
    024import java.util.Set;
    025
    026/**
    027 * <p>The {@code ConfigurationMap} wraps a
    028 * configuration-collection
    029 * {@link org.apache.commons.configuration2.Configuration}
    030 * instance to provide a {@code Map} interface.</p>
    031 *
    032 * <p><em>Note:</em> This implementation is incomplete.</p>
    033 *
    034 * @author <a href="mailto:ricardo.gladwell@btinternet.com">Ricardo Gladwell</a>
    035 * @since 1.0
    036 */
    037public class ConfigurationMap extends AbstractMap<Object, Object>
    038{
    039    /**
    040     * The {@code Configuration} wrapped by this class.
    041     */
    042    private final Configuration configuration;
    043
    044    /**
    045     * Creates a new instance of a {@code ConfigurationMap}
    046     * that wraps the specified {@code Configuration}
    047     * instance.
    048     * @param configuration {@code Configuration}
    049     * instance.
    050     */
    051    public ConfigurationMap(final Configuration configuration)
    052    {
    053        this.configuration = configuration;
    054    }
    055
    056    /**
    057     * Returns the wrapped {@code Configuration} object.
    058     *
    059     * @return the wrapped configuration
    060     * @since 1.2
    061     */
    062    public Configuration getConfiguration()
    063    {
    064        return configuration;
    065    }
    066
    067    /**
    068     * Returns a set with the entries contained in this configuration-based map.
    069     *
    070     * @return a set with the contained entries
    071     * @see java.util.Map#entrySet()
    072     */
    073    @Override
    074    public Set<Map.Entry<Object, Object>> entrySet()
    075    {
    076        return new ConfigurationSet(configuration);
    077    }
    078
    079    /**
    080     * Stores the value for the specified key. The value is stored in the
    081     * underlying configuration.
    082     *
    083     * @param key the key (will be converted to a string)
    084     * @param value the value
    085     * @return the old value of this key or <b>null</b> if it is new
    086     * @see java.util.Map#put(java.lang.Object, java.lang.Object)
    087     */
    088    @Override
    089    public Object put(final Object key, final Object value)
    090    {
    091        final String strKey = String.valueOf(key);
    092        final Object old = configuration.getProperty(strKey);
    093        configuration.setProperty(strKey, value);
    094        return old;
    095    }
    096
    097    /**
    098     * Returns the value of the specified key. The key is converted to a string
    099     * and then passed to the underlying configuration.
    100     *
    101     * @param key the key
    102     * @return the value of this key
    103     * @see java.util.Map#get(java.lang.Object)
    104     */
    105    @Override
    106    public Object get(final Object key)
    107    {
    108        return configuration.getProperty(String.valueOf(key));
    109    }
    110
    111    /**
    112     * Set of entries in the map.
    113     */
    114    static class ConfigurationSet extends AbstractSet<Map.Entry<Object, Object>>
    115    {
    116        /** The configuration mapped to this entry set. */
    117        private final Configuration configuration;
    118
    119        /**
    120         * A Map entry in the ConfigurationMap.
    121         */
    122        private final class Entry implements Map.Entry<Object, Object>
    123        {
    124            /** The key of the map entry. */
    125            private final Object key;
    126
    127            private Entry(final Object key)
    128            {
    129                this.key = key;
    130            }
    131
    132            @Override
    133            public Object getKey()
    134            {
    135                return key;
    136            }
    137
    138            @Override
    139            public Object getValue()
    140            {
    141                return configuration.getProperty((String) key);
    142            }
    143
    144            @Override
    145            public Object setValue(final Object value)
    146            {
    147                final Object old = getValue();
    148                configuration.setProperty((String) key, value);
    149                return old;
    150            }
    151        }
    152
    153        /**
    154         * Iterator over the entries in the ConfigurationMap.
    155         */
    156        private final class ConfigurationSetIterator implements Iterator<Map.Entry<Object, Object>>
    157        {
    158            /** An iterator over the keys in the configuration. */
    159            private final Iterator<String> keys;
    160
    161            private ConfigurationSetIterator()
    162            {
    163                keys = configuration.getKeys();
    164            }
    165
    166            @Override
    167            public boolean hasNext()
    168            {
    169                return keys.hasNext();
    170            }
    171
    172            @Override
    173            public Map.Entry<Object, Object> next()
    174            {
    175                return new Entry(keys.next());
    176            }
    177
    178            @Override
    179            public void remove()
    180            {
    181                keys.remove();
    182            }
    183        }
    184
    185        ConfigurationSet(final Configuration configuration)
    186        {
    187            this.configuration = configuration;
    188        }
    189
    190        /**
    191         * @see java.util.Collection#size()
    192         */
    193        @Override
    194        public int size()
    195        {
    196            // Ouch. Now _that_ one is expensive...
    197            int count = 0;
    198            for (final Iterator<String> iterator = configuration.getKeys(); iterator.hasNext();)
    199            {
    200                iterator.next();
    201                count++;
    202            }
    203            return count;
    204        }
    205
    206        /**
    207         * @see java.util.Collection#iterator()
    208         */
    209        @Override
    210        public Iterator<Map.Entry<Object, Object>> iterator()
    211        {
    212            return new ConfigurationSetIterator();
    213        }
    214    }
    215}