/**************************************************************
 * 
 * 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 INCLUDED_SLIDESHOW_STATE_HXX
#define INCLUDED_SLIDESHOW_STATE_HXX

#include <sal/types.h>
#include <boost/shared_ptr.hpp>


/* Definition of State interface */

namespace slideshow
{
    namespace internal
    {

        /** This interface represents a stateful object.

            The state ID returned by the getStateId() method
            abstractly encodes the object's state. When this ID
            changes, clients can assume that the object's state has
            changed.
         */
        class State
        {
        public:
            virtual ~State() {}

            /// Abstract, numerically encoded state ID 
            typedef ::std::size_t StateId;

            /** This method returns a numerical state identifier.

                The state ID returned by this method abstractly
                encodes the object's state. When this ID changes,
                clients can assume that the object's state has
                changed.

                @return an abstract, numerical state ID. 
             */
            virtual StateId getStateId() const = 0;
        };

        typedef ::boost::shared_ptr< State > StateSharedPtr;
    }
}

#endif /* INCLUDED_SLIDESHOW_STATE_HXX */