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/*=========================================================================
*
* 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 itkIsConvertible_h
#define itkIsConvertible_h
#include "itkMetaProgrammingLibrary.h"
namespace itk
{
/** \cond HIDE_META_PROGRAMMING */
namespace mpl
{
namespace Details
{
/** Helper root class for Meta-programming purpose.
* This class provides two types that help build SFINAE based meta-programs.
* \ingroup MetaProgrammingLibrary
* \ingroup ITKCommon
*/
struct SfinaeTypes
{
typedef char TOne;
typedef struct { char arr__[2]; } TTwo;
};
} // Details namespace
/** Traits that emulates \c std::is_convertible<>.
* \tparam TFrom type to convert from
* \tparam TTo type to convert to
* \return (in \c Value) whether \c TFrom objects can be converted into \c TTo
* objects.
* \warning This version does not support \c void, function pointers, nor arrays.
* \author The definition provided follows the code snippet available in Andrei
* Alexandrescu's <em>Modern C++ Design</em>.
* \ingroup MetaProgrammingLibrary
* \ingroup ITKCommon
*/
template <typename TFrom, typename TTo>
struct IsConvertible
: private Details::SfinaeTypes
{
private:
static TOne Test(TTo);
static TTwo Test(...);
static TFrom MakeT();
public:
static ITK_CONSTEXPR_VAR bool Value = sizeof(Test(MakeT())) == sizeof(TOne);
};
} // itk::mpl namespace
// itk::IsConvertible has moved to itk::mpl.
// Expect itk::IsConvertible to be deprecated.
using mpl::IsConvertible;
/** \endcond */
} // itk namespace
#endif // itkIsConvertible_h
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