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# vigra/static_assert.hxx

    00001 /************************************************************************/
    00002 /*                                                                      */
    00003 /*               Copyright 2004-2005 by Ullrich Koethe                  */
    00004 /*       Cognitive Systems Group, University of Hamburg, Germany        */
    00005 /*                                                                      */
    00006 /*    This file is part of the VIGRA computer vision library.           */
    00007 /*    ( Version 1.6.0, Aug 13 2008 )                                    */
    00008 /*    The VIGRA Website is                                              */
    00009 /*        http://kogs-www.informatik.uni-hamburg.de/~koethe/vigra/      */
    00010 /*    Please direct questions, bug reports, and contributions to        */
    00011 /*        ullrich.koethe@iwr.uni-heidelberg.de    or                    */
    00012 /*        vigra@informatik.uni-hamburg.de                               */
    00013 /*                                                                      */
    00014 /*    Permission is hereby granted, free of charge, to any person       */
    00015 /*    obtaining a copy of this software and associated documentation    */
    00016 /*    files (the "Software"), to deal in the Software without           */
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    00018 /*    copy, modify, merge, publish, distribute, sublicense, and/or      */
    00019 /*    sell copies of the Software, and to permit persons to whom the    */
    00020 /*    Software is furnished to do so, subject to the following          */
    00021 /*    conditions:                                                       */
    00022 /*                                                                      */
    00023 /*    The above copyright notice and this permission notice shall be    */
    00024 /*    included in all copies or substantial portions of the             */
    00025 /*    Software.                                                         */
    00026 /*                                                                      */
    00027 /*    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND    */
    00028 /*    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES   */
    00029 /*    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND          */
    00030 /*    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT       */
    00031 /*    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,      */
    00032 /*    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING      */
    00033 /*    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR     */
    00034 /*    OTHER DEALINGS IN THE SOFTWARE.                                   */
    00035 /*                                                                      */
    00036 /************************************************************************/
    00037
    00038 #ifndef VIGRA_STATIC_ASSERT_HXX
    00039 #define VIGRA_STATIC_ASSERT_HXX
    00040
    00041 // based on the static assertion design in boost::mpl (see www.boost.org)
    00042
    00043 #define VIGRA_PREPROCESSOR_CONCATENATE(a, b) VIGRA_PREPROCESSOR_CONCATENATE_IMPL(a, b)
    00044 #define VIGRA_PREPROCESSOR_CONCATENATE_IMPL(a, b) a ## b
    00045
    00046 namespace vigra {
    00047
    00048 namespace staticAssert {
    00049
    00050 template <bool Predicate>
    00051 struct AssertBool;
    00052
    00053 template <>
    00054 struct AssertBool<true>
    00055 {
    00056     typedef int type;
    00057     typedef void * not_type;
    00058 };
    00059
    00060 template <>
    00061 struct AssertBool<false>
    00062 {
    00063     typedef void * type;
    00064     typedef int not_type;
    00065 };
    00066
    00067 template <class T>
    00068 struct Assert;
    00069
    00070 template <>
    00071 struct Assert<VigraTrueType>
    00072 {
    00073     typedef int type;
    00074     typedef void * not_type;
    00075 };
    00076
    00077 template <>
    00078 struct Assert<VigraFalseType>
    00079 {
    00080     typedef void * type;
    00081     typedef int not_type;
    00082 };
    00083
    00084 struct failure{};
    00085 struct success {};
    00086 inline int check( success ) { return 0; }
    00087
    00088 template< typename Predicate >
    00089 failure ************ (Predicate::************
    00090       assertImpl( void (*)(Predicate), typename Predicate::not_type )
    00091     );
    00092
    00093 template< typename Predicate >
    00094 success
    00095 assertImpl( void (*)(Predicate), typename Predicate::type );
    00096
    00097 /* Usage:
    00098
    00099 1. Define an assertion class, derived from vigra::staticAssert::Assert,
    00100    whose name serves as an error message:
    00101
    00102     template <int N>
    00103     struct FixedPoint_overflow_error__More_than_31_bits_requested
    00104     : vigra::staticAssert::AssertBool<(N < 32)>
    00105     {};
    00106
    00107 2. Call VIGRA_STATIC_ASSERT() with the assertion class:
    00108
    00109     template <int N>
    00110     void test()
    00111     {
    00112         // signal error if N > 31
    00113         VIGRA_STATIC_ASSERT((FixedPoint_overflow_error__More_than_31_bits_requested<N>));
    00114     }
    00115
    00116 TODO: provide more assertion base classes for other (non boolean) types of tests
    00117 */
    00118 #if !defined(__GNUC__) || __GNUC__ > 2
    00119 #define VIGRA_STATIC_ASSERT(Predicate) \
    00120 enum { \
    00121     VIGRA_PREPROCESSOR_CONCATENATE(vigra_assertion_in_line_, __LINE__) = sizeof( \
    00122          staticAssert::check( \
    00123               staticAssert::assertImpl( (void (*) Predicate)0, 1 ) \
    00124             ) \
    00125         ) \
    00126 }
    00127 #else
    00128 #define VIGRA_STATIC_ASSERT(Predicate)
    00129 #endif
    00130
    00131 } // namespace staticAssert
    00132
    00133 } // namespace vigra
    00134
    00135 #endif // VIGRA_STATIC_ASSERT_HXX

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python VIGRA 1.6.0 (13 Aug 2008)