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 * @param <K> the type of the keys in this map
048 * @param <V> the type of the values in this map
049 * @since 3.0
050 */
051public class PredicatedMap<K, V>
052        extends AbstractInputCheckedMapDecorator<K, V>
053        implements Serializable {
054
055    /** Serialization version */
056    private static final long serialVersionUID = 7412622456128415156L;
057
058    /** The key predicate to use */
059    protected final Predicate<? super K> keyPredicate;
060
061    /** The value predicate to use */
062    protected final Predicate<? super V> valuePredicate;
063
064    /**
065     * Factory method to create a predicated (validating) map.
066     * <p>
067     * If there are any elements already in the list being decorated, they
068     * are validated.
069     *
070     * @param <K>  the key type
071     * @param <V>  the value type
072     * @param map  the map to decorate, must not be null
073     * @param keyPredicate  the predicate to validate the keys, null means no check
074     * @param valuePredicate  the predicate to validate to values, null means no check
075     * @return a new predicated map
076     * @throws NullPointerException if the map is null
077     * @since 4.0
078     */
079    public static <K, V> PredicatedMap<K, V> predicatedMap(final Map<K, V> map,
080                                                           final Predicate<? super K> keyPredicate,
081                                                           final Predicate<? super V> valuePredicate) {
082        return new PredicatedMap<>(map, keyPredicate, valuePredicate);
083    }
084
085    //-----------------------------------------------------------------------
086    /**
087     * Constructor that wraps (not copies).
088     *
089     * @param map  the map to decorate, must not be null
090     * @param keyPredicate  the predicate to validate the keys, null means no check
091     * @param valuePredicate  the predicate to validate to values, null means no check
092     * @throws NullPointerException if the map is null
093     */
094    protected PredicatedMap(final Map<K, V> map, final Predicate<? super K> keyPredicate,
095                            final Predicate<? super V> valuePredicate) {
096        super(map);
097        this.keyPredicate = keyPredicate;
098        this.valuePredicate = valuePredicate;
099
100        final Iterator<Map.Entry<K, V>> it = map.entrySet().iterator();
101        while (it.hasNext()) {
102            final Map.Entry<K, V> entry = it.next();
103            validate(entry.getKey(), entry.getValue());
104        }
105    }
106
107    //-----------------------------------------------------------------------
108    /**
109     * Write the map out using a custom routine.
110     *
111     * @param out  the output stream
112     * @throws IOException if an error occurs while writing to the stream
113     * @since 3.1
114     */
115    private void writeObject(final ObjectOutputStream out) throws IOException {
116        out.defaultWriteObject();
117        out.writeObject(map);
118    }
119
120    /**
121     * Read the map in using a custom routine.
122     *
123     * @param in  the input stream
124     * @throws IOException if an error occurs while reading from the stream
125     * @throws ClassNotFoundException if an object read from the stream can not be loaded
126     * @since 3.1
127     */
128    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
129    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
130        in.defaultReadObject();
131        map = (Map<K, V>) in.readObject(); // (1)
132    }
133
134    //-----------------------------------------------------------------------
135    /**
136     * Validates a key value pair.
137     *
138     * @param key  the key to validate
139     * @param value  the value to validate
140     * @throws IllegalArgumentException if invalid
141     */
142    protected void validate(final K key, final V value) {
143        if (keyPredicate != null && keyPredicate.evaluate(key) == false) {
144            throw new IllegalArgumentException("Cannot add key - Predicate rejected it");
145        }
146        if (valuePredicate != null && valuePredicate.evaluate(value) == false) {
147            throw new IllegalArgumentException("Cannot add value - Predicate rejected it");
148        }
149    }
150
151    /**
152     * Override to validate an object set into the map via <code>setValue</code>.
153     *
154     * @param value  the value to validate
155     * @return the value itself
156     * @throws IllegalArgumentException if invalid
157     * @since 3.1
158     */
159    @Override
160    protected V checkSetValue(final V value) {
161        if (valuePredicate.evaluate(value) == false) {
162            throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
163        }
164        return value;
165    }
166
167    /**
168     * Override to only return true when there is a value transformer.
169     *
170     * @return true if a value predicate is in use
171     * @since 3.1
172     */
173    @Override
174    protected boolean isSetValueChecking() {
175        return valuePredicate != null;
176    }
177
178    //-----------------------------------------------------------------------
179    @Override
180    public V put(final K key, final V value) {
181        validate(key, value);
182        return map.put(key, value);
183    }
184
185    @Override
186    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
187        for (final Map.Entry<? extends K, ? extends V> entry : mapToCopy.entrySet()) {
188            validate(entry.getKey(), entry.getValue());
189        }
190        super.putAll(mapToCopy);
191    }
192
193}