- /*
- * Copyright 2004 The Apache Software Foundation
- *
- * Licensed 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.collections.map;
-
- import java.lang.reflect.Array;
- import java.util.Iterator;
- import java.util.Map;
- import java.util.Set;
-
- import org.apache.commons.collections.iterators.AbstractIteratorDecorator;
- import org.apache.commons.collections.keyvalue.AbstractMapEntryDecorator;
- import org.apache.commons.collections.set.AbstractSetDecorator;
-
- /**
- * An abstract base class that simplifies the task of creating map decorators.
- * <p>
- * The Map API is very difficult to decorate correctly, and involves implementing
- * lots of different classes. This class exists to provide a simpler API.
- * <p>
- * Special hook methods are provided that are called when objects are added to
- * the map. By overriding these methods, the input can be validated or manipulated.
- * In addition to the main map methods, the entrySet is also affected, which is
- * the hardest part of writing map implementations.
- * <p>
- * This class is package-scoped, and may be withdrawn or replaced in future
- * versions of Commons Collections.
- *
- * @since Commons Collections 3.1
- * @version $Revision: 1.2 $ $Date: 2004/05/21 22:01:04 $
- *
- * @author Stephen Colebourne
- */
- abstract class AbstractInputCheckedMapDecorator
- extends AbstractMapDecorator {
-
- /**
- * Constructor only used in deserialization, do not use otherwise.
- */
- protected AbstractInputCheckedMapDecorator() {
- super();
- }
-
- /**
- * Constructor that wraps (not copies).
- *
- * @param map the map to decorate, must not be null
- * @throws IllegalArgumentException if map is null
- */
- protected AbstractInputCheckedMapDecorator(Map map) {
- super(map);
- }
-
- //-----------------------------------------------------------------------
- /**
- * Hook method called when a value is being set using <code>setValue</code>.
- * <p>
- * An implementation may validate the value and throw an exception
- * or it may transform the value into another object.
- * <p>
- * This implementation returns the input value.
- *
- * @param value the value to check
- * @throws UnsupportedOperationException if the map may not be changed by setValue
- * @throws IllegalArgumentException if the specified value is invalid
- * @throws ClassCastException if the class of the specified value is invalid
- * @throws NullPointerException if the specified value is null and nulls are invalid
- */
- protected abstract Object checkSetValue(Object value);
-
- /**
- * Hook method called to determine if <code>checkSetValue</code> has any effect.
- * <p>
- * An implementation should return false if the <code>checkSetValue</code> method
- * has no effect as this optimises the implementation.
- * <p>
- * This implementation returns <code>true</code>.
- *
- * @param value the value to check
- */
- protected boolean isSetValueChecking() {
- return true;
- }
-
- //-----------------------------------------------------------------------
- public Set entrySet() {
- if (isSetValueChecking()) {
- return new EntrySet(map.entrySet(), this);
- } else {
- return map.entrySet();
- }
- }
-
- //-----------------------------------------------------------------------
- /**
- * Implementation of an entry set that checks additions via setValue.
- */
- static class EntrySet extends AbstractSetDecorator {
-
- /** The parent map */
- private final AbstractInputCheckedMapDecorator parent;
-
- protected EntrySet(Set set, AbstractInputCheckedMapDecorator parent) {
- super(set);
- this.parent = parent;
- }
-
- public Iterator iterator() {
- return new EntrySetIterator(collection.iterator(), parent);
- }
-
- public Object[] toArray() {
- Object[] array = collection.toArray();
- for (int i = 0; i < array.length; i++) {
- array[i] = new MapEntry((Map.Entry) array[i], parent);
- }
- return array;
- }
-
- public Object[] toArray(Object array[]) {
- Object[] result = array;
- if (array.length > 0) {
- // we must create a new array to handle multi-threaded situations
- // where another thread could access data before we decorate it
- result = (Object[]) Array.newInstance(array.getClass().getComponentType(), 0);
- }
- result = collection.toArray(result);
- for (int i = 0; i < result.length; i++) {
- result[i] = new MapEntry((Map.Entry) result[i], parent);
- }
-
- // check to see if result should be returned straight
- if (result.length > array.length) {
- return result;
- }
-
- // copy back into input array to fulfil the method contract
- System.arraycopy(result, 0, array, 0, result.length);
- if (array.length > result.length) {
- array[result.length] = null;
- }
- return array;
- }
- }
-
- /**
- * Implementation of an entry set iterator that checks additions via setValue.
- */
- static class EntrySetIterator extends AbstractIteratorDecorator {
-
- /** The parent map */
- private final AbstractInputCheckedMapDecorator parent;
-
- protected EntrySetIterator(Iterator iterator, AbstractInputCheckedMapDecorator parent) {
- super(iterator);
- this.parent = parent;
- }
-
- public Object next() {
- Map.Entry entry = (Map.Entry) iterator.next();
- return new MapEntry(entry, parent);
- }
- }
-
- /**
- * Implementation of a map entry that checks additions via setValue.
- */
- static class MapEntry extends AbstractMapEntryDecorator {
-
- /** The parent map */
- private final AbstractInputCheckedMapDecorator parent;
-
- protected MapEntry(Map.Entry entry, AbstractInputCheckedMapDecorator parent) {
- super(entry);
- this.parent = parent;
- }
-
- public Object setValue(Object value) {
- value = parent.checkSetValue(value);
- return entry.setValue(value);
- }
- }
-
- }