State.h
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1//===========================================================================
2/*!
3 *
4 *
5 * \brief Class which externalizes the state of an Object.
6 *
7 *
8 *
9 * \author O. Krause
10 * \date 2012
11 *
12 *
13 * \par Copyright 1995-2017 Shark Development Team
14 *
15 * <BR><HR>
16 * This file is part of Shark.
17 * <https://shark-ml.github.io/Shark/>
18 *
19 * Shark is free software: you can redistribute it and/or modify
20 * it under the terms of the GNU Lesser General Public License as published
21 * by the Free Software Foundation, either version 3 of the License, or
22 * (at your option) any later version.
23 *
24 * Shark is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 * GNU Lesser General Public License for more details.
28 *
29 * You should have received a copy of the GNU Lesser General Public License
30 * along with Shark. If not, see <http://www.gnu.org/licenses/>.
31 *
32 */
33//===========================================================================
34
35#ifndef SHARK_CORE_STATE_H
36#define SHARK_CORE_STATE_H
37
38#include <boost/cast.hpp>
39
40namespace shark{
41
42
43/// \brief Represents the State of an Object.
44///
45/// Often the State of an object is changed during usage.
46/// This, however, makes it impossible to use the object in a
47/// multithreaded environment in parallel. The solution is to externalize
48/// the state, so that every thread can have it's own storage.
49struct State{
50
51 ///\brief prevents that this class can be instantiated
52 virtual ~State(){};
53
54 ///\brief Safely downcast State to it's derived type.
55 ///
56 ///Tries to do a safe cast from State to it's derived type.
57 ///The program is terminated in debug mode, if the wrong Type
58 ///was used.
59 template<class DerivedStateType>
60 DerivedStateType const& toState()const{
61 return *boost::polymorphic_downcast<DerivedStateType const*>(this);
62 }
63
64 template<class DerivedStateType>
65 DerivedStateType & toState(){
66 return *boost::polymorphic_downcast<DerivedStateType*>(this);
67 }
68};
69
70///\brief Default State of an Object which does not need a State
71struct EmptyState:public State{
72};
73}
74#endif