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 */
017package org.apache.commons.collections4.map;
018
019import java.io.IOException;
020import java.io.ObjectInputStream;
021import java.io.ObjectOutputStream;
022import java.io.Serializable;
023import java.util.Iterator;
024import java.util.Map;
025
026import org.apache.commons.collections4.Predicate;
027
028/**
029 * Decorates another <code>Map</code> to validate that additions
030 * match a specified predicate.
031 * <p>
032 * This map exists to provide validation for the decorated map.
033 * It is normally created to decorate an empty map.
034 * If an object cannot be added to the map, an IllegalArgumentException is thrown.
035 * <p>
036 * One usage would be to ensure that no null keys are added to the map.
037 * <pre>Map map = PredicatedSet.decorate(new HashMap(), NotNullPredicate.INSTANCE, null);</pre>
038 * <p>
039 * <strong>Note that PredicatedMap is not synchronized and is not thread-safe.</strong>
040 * If you wish to use this map from multiple threads concurrently, you must use
041 * appropriate synchronization. The simplest approach is to wrap this map
042 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
043 * exceptions when accessed by concurrent threads without synchronization.
044 * <p>
045 * This class is Serializable from Commons Collections 3.1.
046 *
047 * @since 3.0
048 * @version $Id: PredicatedMap.html 887892 2013-11-24 13:43:45Z tn $
049 */
050public class PredicatedMap<K, V>
051        extends AbstractInputCheckedMapDecorator<K, V>
052        implements Serializable {
053
054    /** Serialization version */
055    private static final long serialVersionUID = 7412622456128415156L;
056
057    /** The key predicate to use */
058    protected final Predicate<? super K> keyPredicate;
059
060    /** The value predicate to use */
061    protected final Predicate<? super V> valuePredicate;
062
063    /**
064     * Factory method to create a predicated (validating) map.
065     * <p>
066     * If there are any elements already in the list being decorated, they
067     * are validated.
068     *
069     * @param <K>  the key type
070     * @param <V>  the value type
071     * @param map  the map to decorate, must not be null
072     * @param keyPredicate  the predicate to validate the keys, null means no check
073     * @param valuePredicate  the predicate to validate to values, null means no check
074     * @return a new predicated map
075     * @throws IllegalArgumentException if the map is null
076     * @since 4.0
077     */
078    public static <K, V> PredicatedMap<K, V> predicatedMap(final Map<K, V> map,
079                                                           final Predicate<? super K> keyPredicate,
080                                                           final Predicate<? super V> valuePredicate) {
081        return new PredicatedMap<K, V>(map, keyPredicate, valuePredicate);
082    }
083
084    //-----------------------------------------------------------------------
085    /**
086     * Constructor that wraps (not copies).
087     *
088     * @param map  the map to decorate, must not be null
089     * @param keyPredicate  the predicate to validate the keys, null means no check
090     * @param valuePredicate  the predicate to validate to values, null means no check
091     * @throws IllegalArgumentException if the map is null
092     */
093    protected PredicatedMap(final Map<K, V> map, final Predicate<? super K> keyPredicate,
094                            final Predicate<? super V> valuePredicate) {
095        super(map);
096        this.keyPredicate = keyPredicate;
097        this.valuePredicate = valuePredicate;
098
099        final Iterator<Map.Entry<K, V>> it = map.entrySet().iterator();
100        while (it.hasNext()) {
101            final Map.Entry<K, V> entry = it.next();
102            validate(entry.getKey(), entry.getValue());
103        }
104    }
105
106    //-----------------------------------------------------------------------
107    /**
108     * Write the map out using a custom routine.
109     *
110     * @param out  the output stream
111     * @throws IOException
112     * @since 3.1
113     */
114    private void writeObject(final ObjectOutputStream out) throws IOException {
115        out.defaultWriteObject();
116        out.writeObject(map);
117    }
118
119    /**
120     * Read the map in using a custom routine.
121     *
122     * @param in  the input stream
123     * @throws IOException
124     * @throws ClassNotFoundException
125     * @since 3.1
126     */
127    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
128    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
129        in.defaultReadObject();
130        map = (Map<K, V>) in.readObject(); // (1)
131    }
132
133    //-----------------------------------------------------------------------
134    /**
135     * Validates a key value pair.
136     *
137     * @param key  the key to validate
138     * @param value  the value to validate
139     * @throws IllegalArgumentException if invalid
140     */
141    protected void validate(final K key, final V value) {
142        if (keyPredicate != null && keyPredicate.evaluate(key) == false) {
143            throw new IllegalArgumentException("Cannot add key - Predicate rejected it");
144        }
145        if (valuePredicate != null && valuePredicate.evaluate(value) == false) {
146            throw new IllegalArgumentException("Cannot add value - Predicate rejected it");
147        }
148    }
149
150    /**
151     * Override to validate an object set into the map via <code>setValue</code>.
152     *
153     * @param value  the value to validate
154     * @return the value itself
155     * @throws IllegalArgumentException if invalid
156     * @since 3.1
157     */
158    @Override
159    protected V checkSetValue(final V value) {
160        if (valuePredicate.evaluate(value) == false) {
161            throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
162        }
163        return value;
164    }
165
166    /**
167     * Override to only return true when there is a value transformer.
168     *
169     * @return true if a value predicate is in use
170     * @since 3.1
171     */
172    @Override
173    protected boolean isSetValueChecking() {
174        return valuePredicate != null;
175    }
176
177    //-----------------------------------------------------------------------
178    @Override
179    public V put(final K key, final V value) {
180        validate(key, value);
181        return map.put(key, value);
182    }
183
184    @Override
185    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
186        for (final Map.Entry<? extends K, ? extends V> entry : mapToCopy.entrySet()) {
187            validate(entry.getKey(), entry.getValue());
188        }
189        super.putAll(mapToCopy);
190    }
191
192}