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https://gitlab.kitware.com/vtk/vtk-m
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5773ea3e13
Currently, VTK-m is using C++11. However, it is often useful to use features in the `std` namespace that are defined for C++14 or later. We can provide our own versions (sometimes), but it is preferable to use the version provided by the compiler if available. There were already some examples of defining portable versions of C++14 and C++17 classes in a `vtkmstd` namespace, but these were sprinkled around the source code. There is now a top level `vtkmstd` directory and in it are header files that provide portable versions of these future C++ classes. In each case, preprocessor macros are used to select which version of the class to use.
41 lines
1.2 KiB
C++
41 lines
1.2 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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//
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//============================================================================
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#ifndef vtk_m_std_void_t_h
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#define vtk_m_std_void_t_h
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#include <vtkm/internal/Configure.h>
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namespace vtkmstd
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{
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/// Implementation of std::void_t (C++17):
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/// Allows for specialization of class templates based on members of template
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/// parameters.
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#if defined(VTKM_GCC) && (__GNUC__ < 5)
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// Due to a defect in the wording (CWG 1558) unused parameters in alias templates
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// were not guaranteed to ensure SFINAE, and therefore would consider everything
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// to match the 'true' side. For VTK-m the only known compiler that implemented
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// this defect is GCC < 5.
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template <class... T>
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struct void_pack
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{
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using type = void;
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};
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template <class... T>
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using void_t = typename void_pack<T...>::type;
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#else
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template <typename...>
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using void_t = void;
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#endif
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} // end namespace vtkmstd
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#endif //vtk_m_std_void_t_h
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