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/* * Copyright 2001-2004 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.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. * <p> * 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: 1.7 $ $Date: 2004/05/26 21:58:02 $ * * @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. * <p> * This implementation calls <code>size()</code> 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. * <p> * This implementation calls <code>isEmpty()</code> 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. * <p> * This implementation calls <code>contains()</code> 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. * <p> * This implementation uses an <code>IteratorChain</code>. * * @return an <code>IteratorChain</code> instance which supports * <code>remove()</code>. 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 <code>Collection</code> 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. * <p> * This implementation calls <code>contains()</code> 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. * <p> * This implementation calls <code>removeAll</code> 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. * <p> * This implementation calls <code>retainAll()</code> 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 . * <p> * This implementation calls <code>clear()</code> 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 <i>not</i> 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); } }