mirror of
https://gitlab.kitware.com/vtk/vtk-m
synced 2024-09-19 02:25:42 +00:00
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.
440 lines
14 KiB
C++
440 lines
14 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_internal_Variant_h
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#define vtk_m_internal_Variant_h
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#include <vtkm/internal/VariantDetail.h>
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#include <vtkm/Deprecated.h>
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#include <vtkm/List.h>
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#include <vtkmstd/aligned_union.h>
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#include <vtkmstd/is_trivially_copyable.h>
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namespace vtkm
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{
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namespace internal
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{
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// Forward declaration
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template <typename... Ts>
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class Variant;
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namespace detail
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{
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struct VariantCopyFunctor
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{
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T>
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VTKM_EXEC_CONT void operator()(const T& src, void* destPointer) const noexcept
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{
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new (destPointer) T(src);
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}
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};
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struct VariantDestroyFunctor
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{
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T>
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VTKM_EXEC_CONT void operator()(T& src) const noexcept
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{
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src.~T();
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}
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};
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template <typename... Ts>
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struct AllTriviallyCopyable;
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template <>
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struct AllTriviallyCopyable<> : std::true_type
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{
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};
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template <typename T0>
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struct AllTriviallyCopyable<T0>
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: std::integral_constant<bool, (vtkmstd::is_trivially_copyable<T0>::value)>
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{
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};
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template <typename T0, typename T1>
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struct AllTriviallyCopyable<T0, T1>
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: std::integral_constant<bool,
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(vtkmstd::is_trivially_copyable<T0>::value &&
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vtkmstd::is_trivially_copyable<T1>::value)>
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{
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};
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template <typename T0, typename T1, typename T2>
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struct AllTriviallyCopyable<T0, T1, T2>
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: std::integral_constant<bool,
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(vtkmstd::is_trivially_copyable<T0>::value &&
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vtkmstd::is_trivially_copyable<T1>::value &&
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vtkmstd::is_trivially_copyable<T2>::value)>
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{
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};
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template <typename T0, typename T1, typename T2, typename T3>
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struct AllTriviallyCopyable<T0, T1, T2, T3>
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: std::integral_constant<bool,
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(vtkmstd::is_trivially_copyable<T0>::value &&
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vtkmstd::is_trivially_copyable<T1>::value &&
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vtkmstd::is_trivially_copyable<T2>::value &&
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vtkmstd::is_trivially_copyable<T3>::value)>
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{
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};
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template <typename T0, typename T1, typename T2, typename T3, typename T4, typename... Ts>
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struct AllTriviallyCopyable<T0, T1, T2, T3, T4, Ts...>
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: std::integral_constant<bool,
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(vtkmstd::is_trivially_copyable<T0>::value &&
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vtkmstd::is_trivially_copyable<T1>::value &&
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vtkmstd::is_trivially_copyable<T2>::value &&
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vtkmstd::is_trivially_copyable<T3>::value &&
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vtkmstd::is_trivially_copyable<T4>::value &&
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AllTriviallyCopyable<Ts...>::value)>
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{
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};
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template <typename VariantType>
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struct VariantTriviallyCopyable;
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template <typename... Ts>
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struct VariantTriviallyCopyable<vtkm::internal::Variant<Ts...>> : AllTriviallyCopyable<Ts...>
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{
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};
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template <typename... Ts>
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struct VariantStorageImpl
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{
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typename vtkmstd::aligned_union<0, Ts...>::type Storage;
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vtkm::IdComponent Index = -1;
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template <vtkm::IdComponent Index>
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using TypeAt = typename vtkm::ListAt<vtkm::List<Ts...>, Index>;
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VTKM_EXEC_CONT void* GetPointer() { return reinterpret_cast<void*>(&this->Storage); }
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VTKM_EXEC_CONT const void* GetPointer() const
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{
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return reinterpret_cast<const void*>(&this->Storage);
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}
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VTKM_EXEC_CONT vtkm::IdComponent GetIndex() const noexcept { return this->Index; }
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VTKM_EXEC_CONT bool IsValid() const noexcept { return this->GetIndex() >= 0; }
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VTKM_EXEC_CONT void Reset() noexcept
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{
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if (this->IsValid())
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{
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this->CastAndCall(detail::VariantDestroyFunctor{});
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this->Index = -1;
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}
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}
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template <typename Functor, typename... Args>
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VTKM_EXEC_CONT auto CastAndCall(Functor&& f, Args&&... args) const
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noexcept(noexcept(f(std::declval<const TypeAt<0>&>(), args...)))
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-> decltype(f(std::declval<const TypeAt<0>&>(), args...))
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{
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VTKM_ASSERT(this->IsValid());
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return detail::VariantCastAndCallImpl<decltype(f(std::declval<const TypeAt<0>&>(), args...))>(
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brigand::list<Ts...>{},
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this->GetIndex(),
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std::forward<Functor>(f),
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this->GetPointer(),
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std::forward<Args>(args)...);
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}
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template <typename Functor, typename... Args>
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VTKM_EXEC_CONT auto CastAndCall(Functor&& f, Args&&... args) noexcept(
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noexcept(f(std::declval<const TypeAt<0>&>(), args...)))
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-> decltype(f(std::declval<TypeAt<0>&>(), args...))
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{
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VTKM_ASSERT(this->IsValid());
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return detail::VariantCastAndCallImpl<decltype(f(std::declval<TypeAt<0>&>(), args...))>(
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brigand::list<Ts...>{},
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this->GetIndex(),
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std::forward<Functor>(f),
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this->GetPointer(),
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std::forward<Args>(args)...);
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}
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};
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template <typename VariantType,
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typename TriviallyCopyable = typename VariantTriviallyCopyable<VariantType>::type>
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struct VariantConstructorImpl;
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template <typename... Ts>
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struct VariantConstructorImpl<vtkm::internal::Variant<Ts...>, std::true_type>
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: VariantStorageImpl<Ts...>
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{
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VariantConstructorImpl() = default;
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~VariantConstructorImpl() = default;
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VariantConstructorImpl(const VariantConstructorImpl&) = default;
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VariantConstructorImpl(VariantConstructorImpl&&) = default;
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VariantConstructorImpl& operator=(const VariantConstructorImpl&) = default;
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VariantConstructorImpl& operator=(VariantConstructorImpl&&) = default;
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};
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template <typename... Ts>
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struct VariantConstructorImpl<vtkm::internal::Variant<Ts...>, std::false_type>
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: VariantStorageImpl<Ts...>
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{
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VariantConstructorImpl() = default;
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VTKM_EXEC_CONT ~VariantConstructorImpl() { this->Reset(); }
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VTKM_EXEC_CONT VariantConstructorImpl(const VariantConstructorImpl& src) noexcept
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{
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src.CastAndCall(VariantCopyFunctor{}, this->GetPointer());
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this->Index = src.Index;
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}
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VTKM_EXEC_CONT VariantConstructorImpl(VariantConstructorImpl&& rhs) noexcept
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{
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this->Storage = std::move(rhs.Storage);
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this->Index = std::move(rhs.Index);
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rhs.Index = -1;
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}
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VTKM_EXEC_CONT VariantConstructorImpl& operator=(const VariantConstructorImpl& src) noexcept
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{
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this->Reset();
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src.CastAndCall(detail::VariantCopyFunctor{}, this->GetPointer());
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this->Index = src.Index;
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return *this;
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}
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VTKM_EXEC_CONT VariantConstructorImpl& operator=(VariantConstructorImpl&& rhs) noexcept
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{
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this->Reset();
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this->Storage = std::move(rhs.Storage);
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this->Index = std::move(rhs.Index);
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rhs.Index = -1;
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return *this;
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}
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};
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} // namespace detail
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template <typename... Ts>
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class Variant : detail::VariantConstructorImpl<Variant<Ts...>>
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{
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using Superclass = detail::VariantConstructorImpl<Variant<Ts...>>;
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public:
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/// Returns the index of the type of object this variant is storing. If no object is currently
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/// stored (i.e. the Variant is invalid), -1 is returned.
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///
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VTKM_EXEC_CONT vtkm::IdComponent GetIndex() const noexcept
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{
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return this->Superclass::GetIndex();
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}
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/// Returns true if this Variant is storing an object from one of the types in the template
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/// list, false otherwise.
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///
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VTKM_EXEC_CONT bool IsValid() const noexcept { return this->Superclass::IsValid(); }
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/// Type that converts to a std::integral_constant containing the index of the given type (or
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/// -1 if that type is not in the list).
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template <typename T>
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using IndexOf = vtkm::ListIndexOf<vtkm::List<Ts...>, T>;
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/// Returns the index for the given type (or -1 if that type is not in the list).
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///
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template <typename T>
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VTKM_EXEC_CONT static constexpr vtkm::IdComponent GetIndexOf()
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{
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return IndexOf<T>::value;
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}
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/// Type that converts to the type at the given index.
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///
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template <vtkm::IdComponent Index>
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using TypeAt = typename Superclass::template TypeAt<Index>;
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/// The number of types representable by this Variant.
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///
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static constexpr vtkm::IdComponent NumberOfTypes = vtkm::IdComponent{ sizeof...(Ts) };
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Variant() = default;
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~Variant() = default;
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Variant(const Variant&) = default;
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Variant(Variant&&) = default;
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Variant& operator=(const Variant&) = default;
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Variant& operator=(Variant&&) = default;
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T>
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VTKM_EXEC_CONT Variant(const T& src) noexcept
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{
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constexpr vtkm::IdComponent index = GetIndexOf<T>();
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// Might be a way to use an enable_if to enforce a proper type.
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VTKM_STATIC_ASSERT_MSG(index >= 0, "Attempting to put invalid type into a Variant");
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new (this->GetPointer()) T(src);
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this->Index = index;
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}
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T>
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VTKM_EXEC_CONT Variant(const T&& src) noexcept
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{
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constexpr vtkm::IdComponent index = IndexOf<T>::value;
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// Might be a way to use an enable_if to enforce a proper type.
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VTKM_STATIC_ASSERT_MSG(index >= 0, "Attempting to put invalid type into a Variant");
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new (this->GetPointer()) T(std::move(src));
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this->Index = index;
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}
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template <typename T, typename... Args>
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VTKM_EXEC_CONT T& Emplace(Args&&... args)
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{
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constexpr vtkm::IdComponent I = GetIndexOf<T>();
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VTKM_STATIC_ASSERT_MSG(I >= 0, "Variant::Emplace called with invalid type.");
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return this->EmplaceImpl<T, I>(std::forward<Args>(args)...);
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}
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template <typename T, typename U, typename... Args>
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VTKM_EXEC_CONT T& Emplace(std::initializer_list<U> il, Args&&... args)
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{
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constexpr vtkm::IdComponent I = GetIndexOf<T>();
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VTKM_STATIC_ASSERT_MSG(I >= 0, "Variant::Emplace called with invalid type.");
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return this->EmplaceImpl<T, I>(il, std::forward<Args>(args)...);
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}
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template <vtkm::IdComponent I, typename... Args>
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VTKM_EXEC_CONT TypeAt<I>& Emplace(Args&&... args)
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{
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VTKM_STATIC_ASSERT_MSG((I >= 0) && (I < NumberOfTypes),
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"Variant::Emplace called with invalid index");
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return this->EmplaceImpl<TypeAt<I>, I>(std::forward<Args>(args)...);
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}
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template <vtkm::IdComponent I, typename U, typename... Args>
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VTKM_EXEC_CONT TypeAt<I>& Emplace(std::initializer_list<U> il, Args&&... args)
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{
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VTKM_STATIC_ASSERT_MSG((I >= 0) && (I < NumberOfTypes),
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"Variant::Emplace called with invalid index");
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return this->EmplaceImpl<TypeAt<I>, I>(il, std::forward<Args>(args)...);
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}
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private:
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T, vtkm::IdComponent I, typename... Args>
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VTKM_EXEC_CONT T& EmplaceImpl(Args&&... args)
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{
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this->Reset();
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T* value = new (this->GetPointer()) T{ args... };
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this->Index = I;
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return *value;
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}
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VTKM_SUPPRESS_EXEC_WARNINGS
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template <typename T, vtkm::IdComponent I, typename U, typename... Args>
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VTKM_EXEC_CONT T& EmplaceImpl(std::initializer_list<U> il, Args&&... args)
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{
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this->Reset();
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T* value = new (this->GetPointer()) T(il, args...);
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this->Index = I;
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return *value;
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}
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public:
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//@{
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/// Returns the value as the type at the given index. The behavior is undefined if the
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/// variant does not contain the value at the given index.
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///
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template <vtkm::IdComponent I>
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VTKM_EXEC_CONT TypeAt<I>& Get() noexcept
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{
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VTKM_ASSERT(I == this->GetIndex());
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return *reinterpret_cast<TypeAt<I>*>(this->GetPointer());
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}
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template <vtkm::IdComponent I>
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VTKM_EXEC_CONT const TypeAt<I>& Get() const noexcept
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{
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VTKM_ASSERT(I == this->GetIndex());
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return *reinterpret_cast<const TypeAt<I>*>(this->GetPointer());
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}
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//@}
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//@{
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/// Returns the value as the given type. The behavior is undefined if the variant does not
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/// contain a value of the given type.
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///
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template <typename T>
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VTKM_EXEC_CONT T& Get() noexcept
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{
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VTKM_ASSERT(this->GetIndexOf<T>() == this->GetIndex());
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return *reinterpret_cast<T*>(this->GetPointer());
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}
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template <typename T>
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VTKM_EXEC_CONT const T& Get() const noexcept
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{
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VTKM_ASSERT(this->GetIndexOf<T>() == this->GetIndex());
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return *reinterpret_cast<const T*>(this->GetPointer());
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}
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//@}
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//@{
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/// Given a functor object, calls the functor with the contained object cast to the appropriate
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/// type. If extra \c args are given, then those are also passed to the functor after the cast
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/// object. If the functor returns a value, that value is returned from \c CastAndCall.
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///
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/// The results are undefined if the Variant is not valid.
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///
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template <typename Functor, typename... Args>
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VTKM_EXEC_CONT auto CastAndCall(Functor&& f, Args&&... args) const
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noexcept(noexcept(f(std::declval<const TypeAt<0>&>(), args...)))
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-> decltype(f(std::declval<const TypeAt<0>&>(), args...))
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{
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return this->Superclass::CastAndCall(std::forward<Functor>(f), std::forward<Args>(args)...);
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}
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template <typename Functor, typename... Args>
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VTKM_EXEC_CONT auto CastAndCall(Functor&& f, Args&&... args) noexcept(
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noexcept(f(std::declval<const TypeAt<0>&>(), args...)))
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-> decltype(f(std::declval<TypeAt<0>&>(), args...))
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{
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return this->Superclass::CastAndCall(std::forward<Functor>(f), std::forward<Args>(args)...);
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}
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/// Destroys any object the Variant is holding and sets the Variant to an invalid state. This
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/// method is not thread safe.
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///
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VTKM_EXEC_CONT void Reset() noexcept { this->Superclass::Reset(); }
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};
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/// \brief Convert a ListTag to a Variant.
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///
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/// Depricated. Use ListAsVariant instead.
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///
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template <typename ListTag>
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using ListTagAsVariant VTKM_DEPRECATED(
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1.6,
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"vtkm::ListTag is no longer supported. Use vtkm::List instead.") =
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vtkm::ListApply<ListTag, vtkm::internal::Variant>;
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/// \brief Convert a `List` to a `Variant`.
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///
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template <typename List>
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using ListAsVariant = vtkm::ListApply<List, vtkm::internal::Variant>;
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}
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} // namespace vtkm::internal
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#endif //vtk_m_internal_Variant_h
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