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vigra/static_assert.hxx |

    00001 /************************************************************************/
    00002 /*                                                                      */
    00003 /*               Copyright 2004-2005 by Ullrich Koethe                  */
    00004 /*                                                                      */
    00005 /*    This file is part of the VIGRA computer vision library.           */
    00006 /*    The VIGRA Website is                                              */
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    00009 /*        ullrich.koethe@iwr.uni-heidelberg.de    or                    */
    00010 /*        vigra@informatik.uni-hamburg.de                               */
    00011 /*                                                                      */
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    00019 /*    conditions:                                                       */
    00020 /*                                                                      */
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    00023 /*    Software.                                                         */
    00024 /*                                                                      */
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    00032 /*    OTHER DEALINGS IN THE SOFTWARE.                                   */
    00033 /*                                                                      */
    00034 /************************************************************************/
    00035
    00036 #ifndef VIGRA_STATIC_ASSERT_HXX
    00037 #define VIGRA_STATIC_ASSERT_HXX
    00038
    00039 // based on the static assertion design in boost::mpl (see www.boost.org)
    00040
    00041 #define VIGRA_PREPROCESSOR_CONCATENATE(a, b) VIGRA_PREPROCESSOR_CONCATENATE_IMPL(a, b)
    00042 #define VIGRA_PREPROCESSOR_CONCATENATE_IMPL(a, b) a ## b
    00043
    00044 namespace vigra {
    00045
    00046 namespace staticAssert {
    00047
    00048 template <bool Predicate>
    00049 struct AssertBool;
    00050
    00051 template <>
    00052 struct AssertBool<true>
    00053 {
    00054     typedef int type;
    00055     typedef void * not_type;
    00056 };
    00057
    00058 template <>
    00059 struct AssertBool<false>
    00060 {
    00061     typedef void * type;
    00062     typedef int not_type;
    00063 };
    00064
    00065 template <class T>
    00066 struct Assert;
    00067
    00068 template <>
    00069 struct Assert<VigraTrueType>
    00070 {
    00071     typedef int type;
    00072     typedef void * not_type;
    00073 };
    00074
    00075 template <>
    00076 struct Assert<VigraFalseType>
    00077 {
    00078     typedef void * type;
    00079     typedef int not_type;
    00080 };
    00081
    00082 struct failure{};
    00083 struct success {};
    00084 inline int check( success ) { return 0; }
    00085
    00086 template< typename Predicate >
    00087 failure ************ (Predicate::************
    00088       assertImpl( void (*)(Predicate), typename Predicate::not_type )
    00089     );
    00090
    00091 template< typename Predicate >
    00092 success
    00093 assertImpl( void (*)(Predicate), typename Predicate::type );
    00094
    00095 /* Usage:
    00096
    00097 1. Define an assertion class, derived from vigra::staticAssert::Assert,
    00098    whose name serves as an error message:
    00099
    00100     template <int N>
    00101     struct FixedPoint_overflow_error__More_than_31_bits_requested
    00102     : vigra::staticAssert::AssertBool<(N < 32)>
    00103     {};
    00104
    00105 2. Call VIGRA_STATIC_ASSERT() with the assertion class:
    00106
    00107     template <int N>
    00108     void test()
    00109     {
    00110         // signal error if N > 31
    00111         VIGRA_STATIC_ASSERT((FixedPoint_overflow_error__More_than_31_bits_requested<N>));
    00112     }
    00113
    00114 TODO: provide more assertion base classes for other (non boolean) types of tests
    00115 */
    00116 #if !defined(__GNUC__) || __GNUC__ > 2
    00117 #define VIGRA_STATIC_ASSERT(Predicate) \
    00118 enum { \
    00119     VIGRA_PREPROCESSOR_CONCATENATE(vigra_assertion_in_line_, __LINE__) = sizeof( \
    00120          staticAssert::check( \
    00121               staticAssert::assertImpl( (void (*) Predicate)0, 1 ) \
    00122             ) \
    00123         ) \
    00124 }
    00125 #else
    00126 #define VIGRA_STATIC_ASSERT(Predicate)
    00127 #endif
    00128
    00129 } // namespace staticAssert
    00130
    00131 } // namespace vigra
    00132
    00133 #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 1.7.1 (3 Dec 2010)