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/*
 * 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.collection;

import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.collections4.iterators.EmptyIterator;
import org.apache.commons.collections4.iterators.IteratorChain;
import org.apache.commons.collections4.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. * * @param the type of the elements in the collection * @since 3.0 * @version $Id: CompositeCollection.java 1683951 2015-06-06 20:19:03Z tn $ */ public class CompositeCollection implements Collection, Serializable { /** Serialization version */ private static final long serialVersionUID = 8417515734108306801L; /** CollectionMutator to handle changes to the collection */ private CollectionMutator mutator; /** Collections in the composite */ private final List> all = new ArrayList>(); /** * Create an empty CompositeCollection. */ public CompositeCollection() { super(); } /** * Create a Composite Collection with one collection. * * @param compositeCollection the Collection to be appended to the composite */ public CompositeCollection(final Collection compositeCollection) { super(); addComposited(compositeCollection); } /** * Create a Composite Collection with two collections. * * @param compositeCollection1 the Collection to be appended to the composite * @param compositeCollection2 the Collection to be appended to the composite */ public CompositeCollection(final Collection compositeCollection1, final Collection compositeCollection2) { super(); addComposited(compositeCollection1, compositeCollection2); } /** * Create a Composite Collection with an array of collections. * * @param compositeCollections the collections to composite */ public CompositeCollection(final Collection... compositeCollections) { super(); addComposited(compositeCollections); } //----------------------------------------------------------------------- /** * Gets the size of this composite collection. *

* This implementation calls size() on each collection. * * @return total number of elements in all contained containers */ @Override public int size() { int size = 0; for (final Collection item : all) { size += item.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 */ @Override public boolean isEmpty() { for (final Collection item : all) { if (item.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 */ @Override public boolean contains(final Object obj) { for (final Collection item : all) { if (item.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 */ @Override public Iterator iterator() { if (all.isEmpty()) { return EmptyIterator.emptyIterator(); } final IteratorChain chain = new IteratorChain(); for (final Collection item : all) { chain.addIterator(item.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 */ @Override public Object[] toArray() { final Object[] result = new Object[size()]; int i = 0; for (final Iterator it = 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 the type of the elements in the collection * @param array the array to use, populating if possible * @return an array of all the elements in the collection */ @Override @SuppressWarnings("unchecked") public T[] toArray(final T[] array) { final int size = size(); Object[] result = null; if (array.length >= size) { result = array; } else { result = (Object[]) Array.newInstance(array.getClass().getComponentType(), size); } int offset = 0; for (final Collection item : all) { for (final E e : item) { result[offset++] = e; } } if (result.length > size) { result[size] = null; } return (T[]) result; } /** * Adds an object to the collection, throwing UnsupportedOperationException * unless a CollectionMutator strategy is specified. * * @param obj the object to add * @return {@code 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 */ @Override public boolean add(final E obj) { if (mutator == null) { throw new UnsupportedOperationException( "add() is not supported on CompositeCollection without a CollectionMutator strategy"); } return mutator.add(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 */ @Override public boolean remove(final Object obj) { if (mutator == null) { throw new UnsupportedOperationException( "remove() is not supported on CompositeCollection without a CollectionMutator strategy"); } return mutator.remove(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 */ @Override public boolean containsAll(final Collection coll) { for (final Object item : coll) { if (contains(item) == 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 */ @Override public boolean addAll(final Collection coll) { if (mutator == null) { throw new UnsupportedOperationException( "addAll() is not supported on CompositeCollection without a CollectionMutator strategy"); } return mutator.addAll(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 */ @Override public boolean removeAll(final Collection coll) { if (coll.size() == 0) { return false; } boolean changed = false; for (final Collection item : all) { changed |= item.removeAll(coll); } 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 */ @Override public boolean retainAll(final Collection coll) { boolean changed = false; for (final Collection item : all) { changed |= item.retainAll(coll); } return changed; } /** * Removes all of the elements from this collection . *

* This implementation calls clear() on each collection. * * @throws UnsupportedOperationException if clear is unsupported */ @Override public void clear() { for (final Collection coll : all) { coll.clear(); } } //----------------------------------------------------------------------- /** * Specify a CollectionMutator strategy instance to handle changes. * * @param mutator the mutator to use */ public void setMutator(final CollectionMutator mutator) { this.mutator = mutator; } /** * Add these Collections to the list of collections in this composite * * @param compositeCollection the Collection to be appended to the composite */ public void addComposited(final Collection compositeCollection) { all.add(compositeCollection); } /** * Add these Collections to the list of collections in this composite * * @param compositeCollection1 the Collection to be appended to the composite * @param compositeCollection2 the Collection to be appended to the composite */ public void addComposited(final Collection compositeCollection1, final Collection compositeCollection2) { all.add(compositeCollection1); all.add(compositeCollection2); } /** * Add these Collections to the list of collections in this composite * * @param compositeCollections the Collections to be appended to the composite */ public void addComposited(final Collection... compositeCollections) { all.addAll(Arrays.asList(compositeCollections)); } /** * Removes a collection from the those being decorated in this composite. * * @param coll collection to be removed */ public void removeComposited(final Collection coll) { all.remove(coll); } //----------------------------------------------------------------------- /** * 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 list of all collections in this composite. */ public List> getCollections() { return UnmodifiableList.unmodifiableList(all); } /** * Get the collection mutator to be used for this CompositeCollection. * @return CollectionMutator */ protected CollectionMutator getMutator() { return mutator; } //----------------------------------------------------------------------- /** * Pluggable strategy to handle changes to the composite. * * @param the element being held in the collection */ public interface CollectionMutator extends Serializable { /** * 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 */ boolean add(CompositeCollection composite, List> collections, E 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 */ boolean addAll(CompositeCollection composite, List> 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 */ boolean remove(CompositeCollection composite, List> collections, Object obj); } }





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