1 /*========================================================================= 2 * 3 * Copyright Insight Software Consortium 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0.txt 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 *=========================================================================*/ 18 19 #ifndef itkStaticAssert_h 20 #define itkStaticAssert_h 21 22 #include "itkMacro.h" 23 24 #if ITK_COMPILER_CXX_STATIC_ASSERT 25 // Use the C++11 static_assert if available 26 27 /** Static assertion. 28 * This macro will either emulate static assertions on the current compiler or 29 * use C++11 \c static_assert() keyword. 30 * \param expr compile-time expression to check 31 * \param str string literal that will appear (C++11, GCC 4.3+) as compiler 32 * error if \c expr is \c false. 33 * \ingroup ITKCommon 34 */ 35 # define itkStaticAssert(expr, str) static_assert(expr, str) 36 #elif defined(__GNUC__) && !defined( __INTEL_COMPILER ) 37 // This trick restricts the static assertion to non global contexts (-> functions) 38 # define itkStaticAssert(expr,str) \ 39 ({extern int __attribute__((error(str))) StaticAssertFailure(); \ 40 ((void)((expr) ? 0: StaticAssertFailure()), 0); \ 41 }) 42 #else 43 // Usual trick (boost, clang, ...), but it will loose the error message on the 44 // way 45 # define ITK_JOIN(X,Y) ITK_DO_JOIN(X,Y) 46 # define ITK_DO_JOIN(X,Y) ITK_DO_JOIN2(X,Y) 47 # define ITK_DO_JOIN2(X,Y) X##Y 48 49 namespace itk { 50 /// \cond HIDE_META_PROGRAMMING 51 /** Internal class to emulate static assertions of pre-C++11 compilers. 52 * \sa \c itkStaticAssert 53 * \ingroup ITKCommon 54 */ 55 template <bool V> struct StaticAssertFailure; 56 template <> struct StaticAssertFailure<true>{}; 57 /// \endcond 58 } // itk namespace 59 60 # define itkStaticAssert(expr,str) \ 61 enum { ITK_JOIN(static_assert_typedef, __LINE__) = sizeof(itk::StaticAssertFailure<((expr) == 0 ? false : true)>) }; 62 #endif 63 64 #endif // itkStaticAssert_h 65