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