activemq-cpp/src/main/decaf/util/AbstractSet.h

/*
 * 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.
 */

#ifndef _DECAF_UTIL_ABSTRACTSET_H_
#define _DECAF_UTIL_ABSTRACTSET_H_

#include <decaf/util/Config.h>
#include <decaf/lang/exceptions/UnsupportedOperationException.h>
#include <decaf/lang/exceptions/NullPointerException.h>
#include <decaf/lang/exceptions/IllegalArgumentException.h>
#include <decaf/lang/Iterable.h>
#include <decaf/util/Iterator.h>
#include <decaf/util/Set.h>
#include <memory>

namespace decaf {
namespace util {

    /**
     * This class provides a skeletal implementation of the Set  interface to minimize the
     * effort required to implement this interface.
     *
     * The process of implementing a set by extending this class is identical to that of
     * implementing a Collection by extending AbstractCollection, except that all of the
     * methods and constructors in subclasses of this class must obey the additional
     * constraints imposed by the Set interface (for instance, the add method must not
     * permit addition of multiple instances of an object to a set).
     *
     * @since 1.0
     */
    template<typename E >
    class AbstractSet : public virtual decaf::util::Set<E>,
                        public virtual decaf::util::AbstractCollection<E> {
    public:

        AbstractSet() : AbstractCollection<E>() {}

        virtual ~AbstractSet() {}

        /**
         * {@inheritDoc}
         *
         * This implementation determines which is the smaller of this set and the specified
         * collection, by invoking the size method on each. If this set has fewer elements,
         * then the implementation iterates over this set, checking each element returned by
         * the iterator in turn to see if it is contained in the specified collection. If it
         * is so contained, it is removed from this set with the iterator's remove method. If
         * the specified collection has fewer elements, then the implementation iterates over
         * the specified collection, removing from this set each element returned by the
         * iterator, using this set's remove method.
         *
         * Note that this implementation will throw an UnsupportedOperationException if the
         * iterator returned by the iterator method does not implement the remove method.
         */
        virtual bool removeAll(const Collection<E>& collection) {

            bool result = false;
            if (this->size() <= collection.size()) {

                std::auto_ptr<Iterator<E> > iter(this->iterator());
                while (iter->hasNext()) {
                    if (collection.contains(iter->next())) {
                        iter->remove();
                        result = true;
                    }
                }

            } else {

                std::auto_ptr<Iterator<E> > iter(collection.iterator());
                while (iter->hasNext()) {
                    result = this->remove(iter->next()) || result;
                }
            }

            return result;
        }
    };

}}

#endif /* _DECAF_UTIL_ABSTRACTSET_H_ */