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* Map to validate that additions
* match a specified predicate.
*
* If an object cannot be added to the map, an IllegalArgumentException
* is thrown.
*
* @since Commons Collections 3.0
* @version $Revision: 1.6 $ $Date: 2004/01/14 21:43:11 $
*
* @author Stephen Colebourne
* @author Paul Jack
*/
public class PredicatedMap extends AbstractMapDecorator {
/** 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 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 IllegalArgumentException if the map is null
*/
public static Map decorate(Map map, Predicate keyPredicate, 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 IllegalArgumentException if the map is null
*/
protected PredicatedMap(Map map, Predicate keyPredicate, Predicate valuePredicate) {
super(map);
this.keyPredicate = keyPredicate;
this.valuePredicate = valuePredicate;
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
Object key = entry.getKey();
Object value = entry.getValue();
validate(key, value);
}
}
protected void validate(Object key, Object 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");
}
}
//-----------------------------------------------------------------------
public Object put(Object key, Object value) {
validate(key, value);
return map.put(key, value);
}
public void putAll(Map mapToCopy) {
Iterator it = mapToCopy.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
Object key = entry.getKey();
Object value = entry.getValue();
validate(key, value);
}
map.putAll(mapToCopy);
}
public Set entrySet() {
if (valuePredicate == null) {
return map.entrySet();
}
return new PredicatedMapEntrySet(map.entrySet(), valuePredicate);
}
//-----------------------------------------------------------------------
/**
* Implementation of an entry set that checks (predicates) additions.
*/
static class PredicatedMapEntrySet extends AbstractCollectionDecorator implements Set {
/** The predicate to use */
private final Predicate valuePredicate;
protected PredicatedMapEntrySet(Set set, Predicate valuePred) {
super(set);
this.valuePredicate = valuePred;
}
public Iterator iterator() {
return new PredicatedMapEntrySetIterator(collection.iterator(), valuePredicate);
}
public Object[] toArray() {
Object[] array = collection.toArray();
for (int i = 0; i < array.length; i++) {
array[i] = new PredicatedMapEntry((Map.Entry) array[i], valuePredicate);
}
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 PredicatedMapEntry((Map.Entry) result[i], valuePredicate);
}
// 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.
*/
static class PredicatedMapEntrySetIterator extends AbstractIteratorDecorator {
/** The predicate to use */
private final Predicate valuePredicate;
protected PredicatedMapEntrySetIterator(Iterator iterator, Predicate valuePredicate) {
super(iterator);
this.valuePredicate = valuePredicate;
}
public Object next() {
Map.Entry entry = (Map.Entry) iterator.next();
return new PredicatedMapEntry(entry, valuePredicate);
}
}
/**
* Implementation of a map entry that checks (predicates) additions.
*/
static class PredicatedMapEntry extends AbstractMapEntryDecorator {
/** The predicate to use */
private final Predicate predicate;
protected PredicatedMapEntry(Map.Entry entry, Predicate valuePredicate) {
super(entry);
this.predicate = valuePredicate;
}
public Object setValue(Object obj) {
if (predicate != null && predicate.evaluate(obj) == false) {
throw new IllegalArgumentException("Cannot set value - Predicate rejected it");
}
return entry.setValue(obj);
}
}
}