org.apache.commons.collections4.map.PredicatedMap Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections4.map;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.collections4.Predicate;
/**
* Decorates another Map to validate that additions
* match a specified predicate.
*
* This map exists to provide validation for the decorated map.
* It is normally created to decorate an empty map.
* If an object cannot be added to the map, an IllegalArgumentException is thrown.
*
* One usage would be to ensure that no null keys are added to the map.
*
Map map = PredicatedSet.decorate(new HashMap(), NotNullPredicate.INSTANCE, null);
*
* Note that PredicatedMap is not synchronized and is not thread-safe.
* If you wish to use this map from multiple threads concurrently, you must use
* appropriate synchronization. The simplest approach is to wrap this map
* using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
* exceptions when accessed by concurrent threads without synchronization.
*
* This class is Serializable from Commons Collections 3.1.
*
* @param the type of the keys in this map
* @param the type of the values in this map
* @since 3.0
*/
public class PredicatedMap
extends AbstractInputCheckedMapDecorator
implements Serializable {
/** Serialization version */
private static final long serialVersionUID = 7412622456128415156L;
/** The key predicate to use */
protected final Predicate keyPredicate;
/** The value predicate to use */
protected final Predicate valuePredicate;
/**
* Factory method to create a predicated (validating) map.
*
* If there are any elements already in the list being decorated, they
* are validated.
*
* @param the key type
* @param the value type
* @param map the map to decorate, must not be null
* @param keyPredicate the predicate to validate the keys, null means no check
* @param valuePredicate the predicate to validate to values, null means no check
* @return a new predicated map
* @throws NullPointerException if the map is null
* @since 4.0
*/
public static PredicatedMap predicatedMap(final Map map,
final Predicate keyPredicate,
final Predicate valuePredicate) {
return new PredicatedMap<>(map, keyPredicate, valuePredicate);
}
//-----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* @param map the map to decorate, must not be null
* @param keyPredicate the predicate to validate the keys, null means no check
* @param valuePredicate the predicate to validate to values, null means no check
* @throws NullPointerException if the map is null
*/
protected PredicatedMap(final Map map, final Predicate keyPredicate,
final Predicate valuePredicate) {
super(map);
this.keyPredicate = keyPredicate;
this.valuePredicate = valuePredicate;
final Iterator> it = map.entrySet().iterator();
while (it.hasNext()) {
final Map.Entry entry = it.next();
validate(entry.getKey(), entry.getValue());
}
}
//-----------------------------------------------------------------------
/**
* Write the map out using a custom routine.
*
* @param out the output stream
* @throws IOException if an error occurs while writing to the stream
* @since 3.1
*/
private void writeObject(final ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(map);
}
/**
* Read the map in using a custom routine.
*
* @param in the input stream
* @throws IOException if an error occurs while reading from the stream
* @throws ClassNotFoundException if an object read from the stream can not be loaded
* @since 3.1
*/
@SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
map = (Map) in.readObject(); // (1)
}
//-----------------------------------------------------------------------
/**
* Validates a key value pair.
*
* @param key the key to validate
* @param value the value to validate
* @throws IllegalArgumentException if invalid
*/
protected void validate(final K key, final V value) {
if (keyPredicate != null && keyPredicate.evaluate(key) == false) {
throw new IllegalArgumentException("Cannot add key - Predicate rejected it");
}
if (valuePredicate != null && valuePredicate.evaluate(value) == false) {
throw new IllegalArgumentException("Cannot add value - Predicate rejected it");
}
}
/**
* Override to validate an object set into the map via setValue.
*
* @param value the value to validate
* @return the value itself
* @throws IllegalArgumentException if invalid
* @since 3.1
*/
@Override
protected V checkSetValue(final V value) {
if (valuePredicate.evaluate(value) == false) {
throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
}
return value;
}
/**
* Override to only return true when there is a value transformer.
*
* @return true if a value predicate is in use
* @since 3.1
*/
@Override
protected boolean isSetValueChecking() {
return valuePredicate != null;
}
//-----------------------------------------------------------------------
@Override
public V put(final K key, final V value) {
validate(key, value);
return map.put(key, value);
}
@Override
public void putAll(final Map mapToCopy) {
for (final Map.Entry entry : mapToCopy.entrySet()) {
validate(entry.getKey(), entry.getValue());
}
super.putAll(mapToCopy);
}
}