itkPromoteType.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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 itkPromoteType_h
#define itkPromoteType_h
 
#include "itkMacro.h"
 
// Simplification of boost::common_type
namespace itk
{
 
namespace mpl
{
 
namespace Details
{
 
template <int N, typename TA, typename TB>
struct SizeToType;
 
template <int N>
struct Identity
{
  using Type = char[N];
};
 
#define ITK_ASSOCIATE(N, Typed)                                                                                        \
  template <typename TA, typename TB>                                                                                  \
  struct SizeToType<N, TA, TB>                                                                                         \
  {                                                                                                                    \
    using Type = Typed;                                                                                                \
  };
 
ITK_ASSOCIATE(1, TA);
ITK_ASSOCIATE(2, TB);
 
ITK_ASSOCIATE(3, short);
ITK_ASSOCIATE(4, unsigned short);
ITK_ASSOCIATE(5, int);
ITK_ASSOCIATE(6, unsigned int);
ITK_ASSOCIATE(7, long);
ITK_ASSOCIATE(8, unsigned long);
ITK_ASSOCIATE(9, long long);
ITK_ASSOCIATE(10, unsigned long long);
ITK_ASSOCIATE(11, float);
ITK_ASSOCIATE(12, double);
ITK_ASSOCIATE(13, long double);
#undef ITK_ASSOCIATE
} // namespace Details
 
template <typename TA, typename TB>
struct PromoteType
{
  static TA a;
  static TB b;
 
  // Aimed at supporting overloads
  template <typename T>
  static Details::Identity<1>::Type & Check(typename Details::SizeToType<1, TA, TB>::Type, T);
  template <typename T>
  static Details::Identity<2>::Type & Check(typename Details::SizeToType<2, TA, TB>::Type, T);
 
  // Common numeric types
  static Details::Identity<3>::Type &  Check(typename Details::SizeToType<3, TA, TB>::Type, int);
  static Details::Identity<4>::Type &  Check(typename Details::SizeToType<4, TA, TB>::Type, int);
  static Details::Identity<5>::Type &  Check(typename Details::SizeToType<5, TA, TB>::Type, int);
  static Details::Identity<6>::Type &  Check(typename Details::SizeToType<6, TA, TB>::Type, int);
  static Details::Identity<7>::Type &  Check(typename Details::SizeToType<7, TA, TB>::Type, int);
  static Details::Identity<8>::Type &  Check(typename Details::SizeToType<8, TA, TB>::Type, int);
  static Details::Identity<9>::Type &  Check(typename Details::SizeToType<9, TA, TB>::Type, int);
  static Details::Identity<10>::Type & Check(typename Details::SizeToType<10, TA, TB>::Type, int);
  static Details::Identity<11>::Type & Check(typename Details::SizeToType<11, TA, TB>::Type, int);
  static Details::Identity<12>::Type & Check(typename Details::SizeToType<12, TA, TB>::Type, int);
  static Details::Identity<13>::Type & Check(typename Details::SizeToType<13, TA, TB>::Type, int);
 
public:
  using Type = typename Details::SizeToType<sizeof Check(a + b, 0), TA, TB>::Type;
};
} // end namespace mpl
 
} // end namespace itk
 
#endif // itkPromoteType_h