    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 *      https://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.InvalidObjectException;
    021import java.io.ObjectInputStream;
    022import java.io.ObjectOutputStream;
    023import java.io.Serializable;
    024import java.util.Map;
    025
    026import org.apache.commons.collections4.Predicate;
    027
    028/**
    029 * Decorates another {@code Map} 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 * <p>
    037 * One usage would be to ensure that no null keys are added to the map.
    038 * </p>
    039 * <pre>Map map = PredicatedSet.decorate(new HashMap(), NotNullPredicate.INSTANCE, null);</pre>
    040 * <p>
    041 * <strong>Note that PredicatedMap is not synchronized and is not thread-safe.</strong>
    042 * If you wish to use this map from multiple threads concurrently, you must use
    043 * appropriate synchronization. The simplest approach is to wrap this map
    044 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
    045 * exceptions when accessed by concurrent threads without synchronization.
    046 * </p>
    047 * <p>
    048 * This class is Serializable from Commons Collections 3.1.
    049 * </p>
    050 *
    051 * @param <K> The type of the keys in this map
    052 * @param <V> The type of the values in this map
    053 * @since 3.0
    054 */
    055public class PredicatedMap<K, V>
    056        extends AbstractInputCheckedMapDecorator<K, V>
    057        implements Serializable {
    058
    059    /** Serialization version */
    060    private static final long serialVersionUID = 7412622456128415156L;
    061
    062    /**
    063     * Factory method to create a predicated (validating) map.
    064     * <p>
    065     * If there are any elements already in the list being decorated, they
    066     * are validated.
    067     * </p>
    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 NullPointerException 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<>(map, keyPredicate, valuePredicate);
    082    }
    083
    084    /** The key predicate to use */
    085    protected final Predicate<? super K> keyPredicate;
    086
    087    /** The value predicate to use */
    088    protected final Predicate<? super V> valuePredicate;
    089
    090    /**
    091     * Constructor that wraps (not copies).
    092     *
    093     * @param map  The map to decorate, must not be null
    094     * @param keyPredicate  The predicate to validate the keys, null means no check
    095     * @param valuePredicate  The predicate to validate to values, null means no check
    096     * @throws NullPointerException if the map is null
    097     */
    098    protected PredicatedMap(final Map<K, V> map, final Predicate<? super K> keyPredicate,
    099                            final Predicate<? super V> valuePredicate) {
    100        super(map);
    101        this.keyPredicate = keyPredicate;
    102        this.valuePredicate = valuePredicate;
    103        map.forEach(this::validate);
    104    }
    105
    106    /**
    107     * Override to validate an object set into the map via {@code setValue}.
    108     *
    109     * @param value  The value to validate
    110     * @return The value itself
    111     * @throws IllegalArgumentException if invalid
    112     * @since 3.1
    113     */
    114    @Override
    115    protected V checkSetValue(final V value) {
    116        if (!valuePredicate.test(value)) {
    117            throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
    118        }
    119        return value;
    120    }
    121
    122    /**
    123     * Override to only return true when there is a value transformer.
    124     *
    125     * @return true if a value predicate is in use
    126     * @since 3.1
    127     */
    128    @Override
    129    protected boolean isSetValueChecking() {
    130        return valuePredicate != null;
    131    }
    132
    133    @Override
    134    public V put(final K key, final V value) {
    135        validate(key, value);
    136        return map.put(key, value);
    137    }
    138
    139    @Override
    140    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
    141        for (final Map.Entry<? extends K, ? extends V> entry : mapToCopy.entrySet()) {
    142            validate(entry.getKey(), entry.getValue());
    143        }
    144        super.putAll(mapToCopy);
    145    }
    146
    147    /**
    148     * Deserializes the map in using a custom routine.
    149     *
    150     * @param in  The input stream
    151     * @throws IOException Thrown if an error occurs while reading from the stream
    152     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
    153     * @since 3.1
    154     */
    155    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    156    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    157        in.defaultReadObject();
    158        map = (Map<K, V>) in.readObject(); // (1)
    159        if (map == null) {
    160            throw new InvalidObjectException("Null map");
    161        }
    162        try {
    163            map.forEach(this::validate);
    164        } catch (final IllegalArgumentException ex) {
    165            throw (InvalidObjectException) new InvalidObjectException(ex.getMessage()).initCause(ex);
    166        }
    167    }
    168
    169    /**
    170     * Validates a key value pair.
    171     *
    172     * @param key  The key to validate
    173     * @param value  The value to validate
    174     * @throws IllegalArgumentException if invalid
    175     */
    176    protected void validate(final K key, final V value) {
    177        if (keyPredicate != null && !keyPredicate.test(key)) {
    178            throw new IllegalArgumentException("Cannot add key - Predicate rejected it");
    179        }
    180        if (valuePredicate != null && !valuePredicate.test(value)) {
    181            throw new IllegalArgumentException("Cannot add value - Predicate rejected it");
    182        }
    183    }
    184
    185    /**
    186     * Serializes this object to an ObjectOutputStream.
    187     *
    188     * @param out The target ObjectOutputStream.
    189     * @throws IOException thrown when an I/O errors occur writing to the target stream.
    190     * @since 3.1
    191     */
    192    private void writeObject(final ObjectOutputStream out) throws IOException {
    193        out.defaultWriteObject();
    194        out.writeObject(map);
    195    }
    196
    197}