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