org.apache.commons.collections.collection.CompositeCollection 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.collections.collection;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import org.apache.commons.collections.iterators.EmptyIterator;
import org.apache.commons.collections.iterators.IteratorChain;
import org.apache.commons.collections.list.UnmodifiableList;
/**
* Decorates a collection of other collections to provide a single unified view.
*
* Changes made to this collection will actually be made on the decorated collection.
* Add and remove operations require the use of a pluggable strategy. If no
* strategy is provided then add and remove are unsupported.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
*
* @author Brian McCallister
* @author Stephen Colebourne
* @author Phil Steitz
*/
public class CompositeCollection implements Collection {
/** CollectionMutator to handle changes to the collection */
protected CollectionMutator mutator;
/** Collections in the composite */
protected Collection[] all;
/**
* Create an empty CompositeCollection.
*/
public CompositeCollection() {
super();
this.all = new Collection[0];
}
/**
* Create a Composite Collection with only coll composited.
*
* @param coll a collection to decorate
*/
public CompositeCollection(Collection coll) {
this();
this.addComposited(coll);
}
/**
* Create a CompositeCollection with colls as the initial list of
* composited collections.
*
* @param colls an array of collections to decorate
*/
public CompositeCollection(Collection[] colls) {
this();
this.addComposited(colls);
}
//-----------------------------------------------------------------------
/**
* Gets the size of this composite collection.
*
* This implementation calls size() on each collection.
*
* @return total number of elements in all contained containers
*/
public int size() {
int size = 0;
for (int i = this.all.length - 1; i >= 0; i--) {
size += this.all[i].size();
}
return size;
}
/**
* Checks whether this composite collection is empty.
*
* This implementation calls isEmpty() on each collection.
*
* @return true if all of the contained collections are empty
*/
public boolean isEmpty() {
for (int i = this.all.length - 1; i >= 0; i--) {
if (this.all[i].isEmpty() == false) {
return false;
}
}
return true;
}
/**
* Checks whether this composite collection contains the object.
*
* This implementation calls contains() on each collection.
*
* @param obj the object to search for
* @return true if obj is contained in any of the contained collections
*/
public boolean contains(Object obj) {
for (int i = this.all.length - 1; i >= 0; i--) {
if (this.all[i].contains(obj)) {
return true;
}
}
return false;
}
/**
* Gets an iterator over all the collections in this composite.
*
* This implementation uses an IteratorChain.
*
* @return an IteratorChain instance which supports
* remove(). Iteration occurs over contained collections in
* the order they were added, but this behavior should not be relied upon.
* @see IteratorChain
*/
public Iterator iterator() {
if (this.all.length == 0) {
return EmptyIterator.INSTANCE;
}
IteratorChain chain = new IteratorChain();
for (int i = 0; i < this.all.length; ++i) {
chain.addIterator(this.all[i].iterator());
}
return chain;
}
/**
* Returns an array containing all of the elements in this composite.
*
* @return an object array of all the elements in the collection
*/
public Object[] toArray() {
final Object[] result = new Object[this.size()];
int i = 0;
for (Iterator it = this.iterator(); it.hasNext(); i++) {
result[i] = it.next();
}
return result;
}
/**
* Returns an object array, populating the supplied array if possible.
* See Collection interface for full details.
*
* @param array the array to use, populating if possible
* @return an array of all the elements in the collection
*/
public Object[] toArray(Object[] array) {
int size = this.size();
Object[] result = null;
if (array.length >= size) {
result = array;
}
else {
result = (Object[]) Array.newInstance(array.getClass().getComponentType(), size);
}
int offset = 0;
for (int i = 0; i < this.all.length; ++i) {
for (Iterator it = this.all[i].iterator(); it.hasNext();) {
result[offset++] = it.next();
}
}
if (result.length > size) {
result[size] = null;
}
return result;
}
/**
* Adds an object to the collection, throwing UnsupportedOperationException
* unless a CollectionMutator strategy is specified.
*
* @param obj the object to add
* @return true if the collection was modified
* @throws UnsupportedOperationException if CollectionMutator hasn't been set
* @throws UnsupportedOperationException if add is unsupported
* @throws ClassCastException if the object cannot be added due to its type
* @throws NullPointerException if the object cannot be added because its null
* @throws IllegalArgumentException if the object cannot be added
*/
public boolean add(Object obj) {
if (this.mutator == null) {
throw new UnsupportedOperationException(
"add() is not supported on CompositeCollection without a CollectionMutator strategy");
}
return this.mutator.add(this, this.all, obj);
}
/**
* Removes an object from the collection, throwing UnsupportedOperationException
* unless a CollectionMutator strategy is specified.
*
* @param obj the object being removed
* @return true if the collection is changed
* @throws UnsupportedOperationException if removed is unsupported
* @throws ClassCastException if the object cannot be removed due to its type
* @throws NullPointerException if the object cannot be removed because its null
* @throws IllegalArgumentException if the object cannot be removed
*/
public boolean remove(Object obj) {
if (this.mutator == null) {
throw new UnsupportedOperationException(
"remove() is not supported on CompositeCollection without a CollectionMutator strategy");
}
return this.mutator.remove(this, this.all, obj);
}
/**
* Checks whether this composite contains all the elements in the specified collection.
*
* This implementation calls contains() for each element in the
* specified collection.
*
* @param coll the collection to check for
* @return true if all elements contained
*/
public boolean containsAll(Collection coll) {
for (Iterator it = coll.iterator(); it.hasNext();) {
if (this.contains(it.next()) == false) {
return false;
}
}
return true;
}
/**
* Adds a collection of elements to this collection, throwing
* UnsupportedOperationException unless a CollectionMutator strategy is specified.
*
* @param coll the collection to add
* @return true if the collection was modified
* @throws UnsupportedOperationException if CollectionMutator hasn't been set
* @throws UnsupportedOperationException if add is unsupported
* @throws ClassCastException if the object cannot be added due to its type
* @throws NullPointerException if the object cannot be added because its null
* @throws IllegalArgumentException if the object cannot be added
*/
public boolean addAll(Collection coll) {
if (this.mutator == null) {
throw new UnsupportedOperationException(
"addAll() is not supported on CompositeCollection without a CollectionMutator strategy");
}
return this.mutator.addAll(this, this.all, coll);
}
/**
* Removes the elements in the specified collection from this composite collection.
*
* This implementation calls removeAll on each collection.
*
* @param coll the collection to remove
* @return true if the collection was modified
* @throws UnsupportedOperationException if removeAll is unsupported
*/
public boolean removeAll(Collection coll) {
if (coll.size() == 0) {
return false;
}
boolean changed = false;
for (int i = this.all.length - 1; i >= 0; i--) {
changed = (this.all[i].removeAll(coll) || changed);
}
return changed;
}
/**
* Retains all the elements in the specified collection in this composite collection,
* removing all others.
*
* This implementation calls retainAll() on each collection.
*
* @param coll the collection to remove
* @return true if the collection was modified
* @throws UnsupportedOperationException if retainAll is unsupported
*/
public boolean retainAll(final Collection coll) {
boolean changed = false;
for (int i = this.all.length - 1; i >= 0; i--) {
changed = (this.all[i].retainAll(coll) || changed);
}
return changed;
}
/**
* Removes all of the elements from this collection .
*
* This implementation calls clear() on each collection.
*
* @throws UnsupportedOperationException if clear is unsupported
*/
public void clear() {
for (int i = 0; i < this.all.length; ++i) {
this.all[i].clear();
}
}
//-----------------------------------------------------------------------
/**
* Specify a CollectionMutator strategy instance to handle changes.
*
* @param mutator the mutator to use
*/
public void setMutator(CollectionMutator mutator) {
this.mutator = mutator;
}
/**
* Add these Collections to the list of collections in this composite
*
* @param comps Collections to be appended to the composite
*/
public void addComposited(Collection[] comps) {
ArrayList list = new ArrayList(Arrays.asList(this.all));
list.addAll(Arrays.asList(comps));
all = (Collection[]) list.toArray(new Collection[list.size()]);
}
/**
* Add an additional collection to this composite.
*
* @param c the collection to add
*/
public void addComposited(Collection c) {
this.addComposited(new Collection[]{c});
}
/**
* Add two additional collections to this composite.
*
* @param c the first collection to add
* @param d the second collection to add
*/
public void addComposited(Collection c, Collection d) {
this.addComposited(new Collection[]{c, d});
}
/**
* Removes a collection from the those being decorated in this composite.
*
* @param coll collection to be removed
*/
public void removeComposited(Collection coll) {
ArrayList list = new ArrayList(this.all.length);
list.addAll(Arrays.asList(this.all));
list.remove(coll);
this.all = (Collection[]) list.toArray(new Collection[list.size()]);
}
/**
* Returns a new collection containing all of the elements
*
* @return A new ArrayList containing all of the elements in this composite.
* The new collection is not backed by this composite.
*/
public Collection toCollection() {
return new ArrayList(this);
}
/**
* Gets the collections being decorated.
*
* @return Unmodifiable collection of all collections in this composite.
*/
public Collection getCollections() {
return UnmodifiableList.decorate(Arrays.asList(this.all));
}
//-----------------------------------------------------------------------
/**
* Pluggable strategy to handle changes to the composite.
*/
public interface CollectionMutator {
/**
* Called when an object is to be added to the composite.
*
* @param composite the CompositeCollection being changed
* @param collections all of the Collection instances in this CompositeCollection
* @param obj the object being added
* @return true if the collection is changed
* @throws UnsupportedOperationException if add is unsupported
* @throws ClassCastException if the object cannot be added due to its type
* @throws NullPointerException if the object cannot be added because its null
* @throws IllegalArgumentException if the object cannot be added
*/
public boolean add(CompositeCollection composite, Collection[] collections, Object obj);
/**
* Called when a collection is to be added to the composite.
*
* @param composite the CompositeCollection being changed
* @param collections all of the Collection instances in this CompositeCollection
* @param coll the collection being added
* @return true if the collection is changed
* @throws UnsupportedOperationException if add is unsupported
* @throws ClassCastException if the object cannot be added due to its type
* @throws NullPointerException if the object cannot be added because its null
* @throws IllegalArgumentException if the object cannot be added
*/
public boolean addAll(CompositeCollection composite, Collection[] collections, Collection coll);
/**
* Called when an object is to be removed to the composite.
*
* @param composite the CompositeCollection being changed
* @param collections all of the Collection instances in this CompositeCollection
* @param obj the object being removed
* @return true if the collection is changed
* @throws UnsupportedOperationException if removed is unsupported
* @throws ClassCastException if the object cannot be removed due to its type
* @throws NullPointerException if the object cannot be removed because its null
* @throws IllegalArgumentException if the object cannot be removed
*/
public boolean remove(CompositeCollection composite, Collection[] collections, Object obj);
}
}