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source: code/trunk/src/util/TemplateUtils.h @ 3264

Last change on this file since 3264 was 3233, checked in by rgrieder, 15 years ago

Possibly reinstated code compliance with GCC 4.4
Could anyone with GCC 4.4 please test this?

  • Property svn:eol-style set to native
File size: 3.3 KB
Line 
1/*
2 *   ORXONOX - the hottest 3D action shooter ever to exist
3 *                    > www.orxonox.net <
4 *
5 *
6 *   License notice:
7 *
8 *   This program is free software; you can redistribute it and/or
9 *   modify it under the terms of the GNU General Public License
10 *   as published by the Free Software Foundation; either version 2
11 *   of the License, or (at your option) any later version.
12 *
13 *   This program is distributed in the hope that it will be useful,
14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *   GNU General Public License for more details.
17 *
18 *   You should have received a copy of the GNU General Public License
19 *   along with this program; if not, write to the Free Software
20 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
21 *
22 *   Author:
23 *      Reto Grieder
24 *   Co-authors:
25 *      ...
26 *
27 */
28
29/**
30    @file
31    @brief Declaration of various helper templates.
32*/
33
34#ifndef _TemplateUtils_H__
35#define _TemplateUtils_H__
36
37#include "UtilPrereqs.h"
38
39namespace orxonox
40{
41    /**
42    @brief
43        Use TypeStripper to get rid of the const and the reference of type T
44    @note
45        Main use of this is when trying to instantiate type T as T().
46    */
47    template <class T> struct TypeStripper
48        { typedef T RawType; };
49    template <class T> struct TypeStripper<const T>
50        { typedef T RawType; };
51    template <class T> struct TypeStripper<const T&>
52        { typedef T RawType; };
53
54
55    ///////////////////////////////////////////////////
56    // Static detection of implicit type conversions //
57    ///////////////////////////////////////////////////
58
59// disable warnings about possible loss of data
60#ifdef ORXONOX_COMPILER_MSVC
61#  pragma warning(push)
62#  pragma warning(disable:4244)
63#endif
64// GCC generates warnings when implicitely casting from float to int for instance.
65#ifdef ORXONOX_COMPILER_GCC
66#  pragma GCC system_header
67#endif
68
69    /**
70    @brief
71        Detects whether you can implicitely cast FromType to ToType.
72
73        Usage: ImplicitConversion<FromType, ToType>::exists
74        This gives you a compile time constant boolean in the form of an enum value.
75    @note
76        The idea to use the sizeof() operator on return values to determine function existance
77        is described in 'Modern C++ design' by Alexandrescu (2001).
78    */
79    template <class FromType, class ToType>
80    class ImplicitConversion
81    {
82    private:
83        ImplicitConversion(); ImplicitConversion(const ImplicitConversion&); ~ImplicitConversion();
84        // Gets chosen only if there is an implicit conversion from FromType to ToType.
85        static char test(ToType);
86        // Accepts any argument. Why do we not use a template? The reason is that with templates,
87        // the function above is only taken iff it is an exact type match. But since we want to
88        // check for implicit conversion, we have to use the ellipsis.
89        static long long test(...);
90        static FromType object; // helper object to handle private c'tor and d'tor
91    public:
92        // test(object) only has 'long long' return type iff the compiler doesn't choose test(...)
93        enum { exists = (sizeof(test(object)) == sizeof(char)) };
94    };
95
96#ifdef ORXONOX_COMPILER_MSVC
97#  pragma warning(pop)
98#endif
99
100}
101
102#endif /* _TemplateUtils_H__ */
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