    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 * <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    /** The key predicate to use */
    063    protected final Predicate<? super K> keyPredicate;
    064
    065    /** The value predicate to use */
    066    protected final Predicate<? super V> valuePredicate;
    067
    068    /**
    069     * Factory method to create a predicated (validating) map.
    070     * <p>
    071     * If there are any elements already in the list being decorated, they
    072     * are validated.
    073     *
    074     * @param <K>  the key type
    075     * @param <V>  the value type
    076     * @param map  the map to decorate, must not be null
    077     * @param keyPredicate  the predicate to validate the keys, null means no check
    078     * @param valuePredicate  the predicate to validate to values, null means no check
    079     * @return a new predicated map
    080     * @throws NullPointerException if the map is null
    081     * @since 4.0
    082     */
    083    public static <K, V> PredicatedMap<K, V> predicatedMap(final Map<K, V> map,
    084                                                           final Predicate<? super K> keyPredicate,
    085                                                           final Predicate<? super V> valuePredicate) {
    086        return new PredicatedMap<>(map, keyPredicate, valuePredicate);
    087    }
    088
    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
    104        final Iterator<Map.Entry<K, V>> it = map.entrySet().iterator();
    105        while (it.hasNext()) {
    106            final Map.Entry<K, V> entry = it.next();
    107            validate(entry.getKey(), entry.getValue());
    108        }
    109    }
    110
    111    //-----------------------------------------------------------------------
    112    /**
    113     * Write the map out using a custom routine.
    114     *
    115     * @param out  the output stream
    116     * @throws IOException if an error occurs while writing to the stream
    117     * @since 3.1
    118     */
    119    private void writeObject(final ObjectOutputStream out) throws IOException {
    120        out.defaultWriteObject();
    121        out.writeObject(map);
    122    }
    123
    124    /**
    125     * Read the map in using a custom routine.
    126     *
    127     * @param in  the input stream
    128     * @throws IOException if an error occurs while reading from the stream
    129     * @throws ClassNotFoundException if an object read from the stream can not be loaded
    130     * @since 3.1
    131     */
    132    @SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
    133    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
    134        in.defaultReadObject();
    135        map = (Map<K, V>) in.readObject(); // (1)
    136    }
    137
    138    //-----------------------------------------------------------------------
    139    /**
    140     * Validates a key value pair.
    141     *
    142     * @param key  the key to validate
    143     * @param value  the value to validate
    144     * @throws IllegalArgumentException if invalid
    145     */
    146    protected void validate(final K key, final V value) {
    147        if (keyPredicate != null && keyPredicate.evaluate(key) == false) {
    148            throw new IllegalArgumentException("Cannot add key - Predicate rejected it");
    149        }
    150        if (valuePredicate != null && valuePredicate.evaluate(value) == false) {
    151            throw new IllegalArgumentException("Cannot add value - Predicate rejected it");
    152        }
    153    }
    154
    155    /**
    156     * Override to validate an object set into the map via <code>setValue</code>.
    157     *
    158     * @param value  the value to validate
    159     * @return the value itself
    160     * @throws IllegalArgumentException if invalid
    161     * @since 3.1
    162     */
    163    @Override
    164    protected V checkSetValue(final V value) {
    165        if (valuePredicate.evaluate(value) == false) {
    166            throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
    167        }
    168        return value;
    169    }
    170
    171    /**
    172     * Override to only return true when there is a value transformer.
    173     *
    174     * @return true if a value predicate is in use
    175     * @since 3.1
    176     */
    177    @Override
    178    protected boolean isSetValueChecking() {
    179        return valuePredicate != null;
    180    }
    181
    182    //-----------------------------------------------------------------------
    183    @Override
    184    public V put(final K key, final V value) {
    185        validate(key, value);
    186        return map.put(key, value);
    187    }
    188
    189    @Override
    190    public void putAll(final Map<? extends K, ? extends V> mapToCopy) {
    191        for (final Map.Entry<? extends K, ? extends V> entry : mapToCopy.entrySet()) {
    192            validate(entry.getKey(), entry.getValue());
    193        }
    194        super.putAll(mapToCopy);
    195    }
    196
    197}