text: /*=========================================================================
   *
   *  Copyright Insight Software Consortium
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *         http://www.apache.org/licenses/LICENSE-2.0.txt
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   *=========================================================================*/
  
  #ifndef itkStaticAssert_h
  #define itkStaticAssert_h
  
  #include "itkMacro.h"
  
  #if defined(ITK_HAS_CXX11_STATIC_ASSERT)
  //  Use the C++11 static_assert if available
  
  /** Static assertion.
   * This macro will either emulate static assertions on the current compiler or
   * use C++11 \c static_assert() keyword.
   * \param expr compile-time expression to check
   * \param str  string literal that will appear (C++11, GCC 4.3+) as compiler
   * error if \c expr is \c false.
   * \ingroup ITKCommon
   */
  #   define itkStaticAssert(expr, str) static_assert(expr, str)
  #elif defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__ ) >= 403 && !defined(__clang__) && !defined( __INTEL_COMPILER )
  //  GCC 4.3 is enough for this trick
  //  But it restricts the static assertion to non global contexts (-> functions)
  #   define itkStaticAssert(expr,str)                                  \
        ({extern int __attribute__((error(str))) StaticAssertFailure(); \
         ((void)((expr) ? 0: StaticAssertFailure()), 0);                \
         })
  #else
  //  Usual trick (boost, clang, ...), but it will loose the error message on the
  //  way
  #   define ITK_JOIN(X,Y)     ITK_DO_JOIN(X,Y)
  #   define ITK_DO_JOIN(X,Y)  ITK_DO_JOIN2(X,Y)
  #   define ITK_DO_JOIN2(X,Y) X##Y
  
  namespace itk {
  /// \cond HIDE_META_PROGRAMMING
  /** Internal class to emulate static assertions of pre-C++11 compilers.
   * \sa \c itkStaticAssert
   * \ingroup ITKCommon
   */
  template <bool V> struct StaticAssertFailure;
  template <> struct StaticAssertFailure<true>{};
  /// \endcond
  } // itk namespace
  
  #   define itkStaticAssert(expr,str) \
        enum { ITK_JOIN(static_assert_typedef, __LINE__) = sizeof(itk::StaticAssertFailure<((expr) == 0 ? false : true)>) };
  #endif
  
  #endif // itkStaticAssert_h
  