    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}