text: //============================================================================
  //  Copyright (c) Kitware, Inc.
  //  All rights reserved.
  //  See LICENSE.txt for details.
  //
  //  This software is distributed WITHOUT ANY WARRANTY; without even
  //  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  //  PURPOSE.  See the above copyright notice for more information.
  //============================================================================
  #ifndef vtk_m_ArrayHandleCompositeVector_h
  #define vtk_m_ArrayHandleCompositeVector_h
  
  #include <vtkm/cont/ArrayHandle.h>
  
  #include <vtkm/Deprecated.h>
  #include <vtkm/StaticAssert.h>
  #include <vtkm/Tuple.h>
  #include <vtkm/VecTraits.h>
  
  #include <vtkm/internal/brigand.hpp>
  
  #include <vtkmstd/integer_sequence.h>
  
  #include <type_traits>
  
  namespace vtkm
  {
  namespace cont
  {
  namespace internal
  {
  
  namespace compvec
  {
  
  // AllAreArrayHandles: ---------------------------------------------------------
  // Ensures that all types in ArrayHandlesT... are subclasses of ArrayHandleBase
  template <typename... ArrayHandlesT>
  struct AllAreArrayHandlesImpl;
  
  template <typename Head, typename... Tail>
  struct AllAreArrayHandlesImpl<Head, Tail...>
  {
  private:
    using Next = AllAreArrayHandlesImpl<Tail...>;
    constexpr static bool HeadValid = std::is_base_of<ArrayHandleBase, Head>::value;
  
  public:
    constexpr static bool Value = HeadValid && Next::Value;
  };
  
  template <typename Head>
  struct AllAreArrayHandlesImpl<Head>
  {
    constexpr static bool Value = std::is_base_of<ArrayHandleBase, Head>::value;
  };
  
  template <typename... ArrayHandleTs>
  struct AllAreArrayHandles
  {
    constexpr static bool Value = AllAreArrayHandlesImpl<ArrayHandleTs...>::Value;
  };
  
  // GetValueType: ---------------------------------------------------------------
  // Determines the output `ValueType` of the set of `ArrayHandle` objects. For example, if the input
  // set contains 3 types with `vtkm::Float32` ValueTypes, then the ValueType defined here will be
  // `vtkm::Vec<Float32, 3>`. This also validates that all members have the same `ValueType`.
  
  template <typename ExpectedValueType, typename ArrayType>
  struct CheckValueType
  {
    VTKM_STATIC_ASSERT_MSG((std::is_same<ExpectedValueType, typename ArrayType::ValueType>::value),
                           "ArrayHandleCompositeVector must be built from "
                           "ArrayHandles with the same ValueTypes.");
  };
  
  template <typename ArrayType0, typename... ArrayTypes>
  struct GetValueType
  {
    static constexpr vtkm::IdComponent COUNT =
      static_cast<vtkm::IdComponent>(sizeof...(ArrayTypes)) + 1;
    using ComponentType = typename ArrayType0::ValueType;
    using ValueCheck = vtkm::List<CheckValueType<ComponentType, ArrayTypes>...>;
    using ValueType = vtkm::Vec<ComponentType, COUNT>;
  };
  
  // Special case for only one component
  template <typename ArrayType>
  struct GetValueType<ArrayType>
  {
    static constexpr vtkm::IdComponent COUNT = 1;
    using ComponentType = typename ArrayType::ValueType;
    using ValueType = typename ArrayType::ValueType;
  };
  
  // -----------------------------------------------------------------------------
  // Functors to access Storage methods. This is used with vtkm::Tuple's
  // ForEach and Transform methods.
  
  struct WritePortal
  {
    template <typename ArrayHandle>
    typename ArrayHandle::WritePortalType operator()(const ArrayHandle& array) const
    {
      return array.WritePortal();
    }
  };
  
  struct ReadPortal
  {
    template <typename ArrayHandle>
    typename ArrayHandle::ReadPortalType operator()(const ArrayHandle& array) const
    {
      return array.ReadPortal();
    }
  };
  
  struct Allocate
  {
    vtkm::Id NumValues;
    VTKM_CONT Allocate(vtkm::Id numValues)
      : NumValues(numValues)
    {
    }
  
    template <typename Array>
    VTKM_CONT void operator()(Array& array)
    {
      array.Allocate(this->NumValues);
    }
  };
  
  struct Shrink
  {
    vtkm::Id NumValues;
    VTKM_CONT Shrink(vtkm::Id numValues)
      : NumValues(numValues)
    {
    }
  
    template <typename Array>
    VTKM_CONT void operator()(Array& array)
    {
      array.Shrink(this->NumValues);
    }
  };
  
  struct ReleaseResources
  {
    template <typename Array>
    VTKM_CONT void operator()(Array& array)
    {
      array.ReleaseResources();
    }
  };
  
  // -----------------------------------------------------------------------------
  // Functors to access ArrayTransfer methods. This is used with vtkm::Tuple's
  // ForEach and Transform methods.
  
  template <typename Device>
  struct PrepareForInput
  {
    vtkm::cont::Token& Token;
    VTKM_CONT PrepareForInput(vtkm::cont::Token& token)
      : Token(token)
    {
    }
  
    template <typename Array>
    VTKM_CONT typename Array::template ExecutionTypes<Device>::PortalConst operator()(
      const Array& array)
    {
      return array.PrepareForInput(Device{}, this->Token);
    }
  };
  
  template <typename Device>
  struct PrepareForInPlace
  {
    vtkm::cont::Token& Token;
    VTKM_CONT PrepareForInPlace(vtkm::cont::Token& token)
      : Token(token)
    {
    }
  
    template <typename Array>
    VTKM_CONT typename Array::template ExecutionTypes<Device>::Portal operator()(Array& array)
    {
      return array.PrepareForInPlace(Device{}, this->Token);
    }
  };
  
  template <typename Device>
  struct PrepareForOutput
  {
    vtkm::Id NumValues;
    vtkm::cont::Token& Token;
    VTKM_CONT PrepareForOutput(vtkm::Id numValues, vtkm::cont::Token& token)
      : NumValues(numValues)
      , Token(token)
    {
    }
  
    template <typename Array>
    VTKM_CONT typename Array::template ExecutionTypes<Device>::Portal operator()(Array& array)
    {
      return array.PrepareForOutput(this->NumValues, Device{}, this->Token);
    }
  };
  
  struct ReleaseResourcesExecution
  {
    template <typename Array>
    VTKM_CONT void operator()(Array& array)
    {
      array.ReleaseResourcesExecution();
    }
  };
  
  // ArraySizeValidator: ---------------------------------------------------------
  // Call Exec(ArrayTuple, NumValues) to ensure that all arrays in the tuple have
  // the specified number of values.
  template <std::size_t Index, std::size_t Count, typename TupleType>
  struct ArraySizeValidatorImpl
  {
    using Next = ArraySizeValidatorImpl<Index + 1, Count, TupleType>;
  
    VTKM_CONT
    static bool Exec(const TupleType& tuple, vtkm::Id numVals)
    {
      return vtkm::Get<Index>(tuple).GetNumberOfValues() == numVals && Next::Exec(tuple, numVals);
    }
  };
  
  template <std::size_t Index, typename TupleType>
  struct ArraySizeValidatorImpl<Index, Index, TupleType>
  {
    VTKM_CONT
    static bool Exec(const TupleType&, vtkm::Id) { return true; }
  };
  
  template <typename TupleType>
  struct ArraySizeValidator
  {
    VTKM_CONT
    static bool Exec(const TupleType& tuple, vtkm::Id numVals)
    {
      return ArraySizeValidatorImpl<0, vtkm::TupleSize<TupleType>::value, TupleType>::Exec(tuple,
                                                                                           numVals);
    }
  };
  
  template <typename... PortalList>
  using AllPortalsAreWritable =
    typename brigand::all<brigand::list<PortalList...>,
                          brigand::bind<vtkm::internal::PortalSupportsSets, brigand::_1>>::type;
  
  // GetFromPortals: -------------------------------------------------------------
  // Given a set of array portals as arguments, returns a Vec comprising the values
  // at the provided index.
  VTKM_SUPPRESS_EXEC_WARNINGS
  template <typename... Portals>
  VTKM_EXEC_CONT typename GetValueType<Portals...>::ValueType GetFromPortals(
    vtkm::Id index,
    const Portals&... portals)
  {
    return { portals.Get(index)... };
  }
  
  // SetToPortals: ---------------------------------------------------------------
  // Given a Vec-like object, and index, and a set of array portals, sets each of
  // the portals to the respective component of the Vec.
  VTKM_SUPPRESS_EXEC_WARNINGS
  template <typename ValueType, vtkm::IdComponent... I, typename... Portals>
  VTKM_EXEC_CONT void SetToPortalsImpl(vtkm::Id index,
                                       const ValueType& value,
                                       vtkmstd::integer_sequence<vtkm::IdComponent, I...>,
                                       const Portals&... portals)
  {
    using Traits = vtkm::VecTraits<ValueType>;
    (void)std::initializer_list<bool>{ (portals.Set(index, Traits::GetComponent(value, I)),
                                        false)... };
  }
  
  VTKM_SUPPRESS_EXEC_WARNINGS
  template <typename ValueType, typename... Portals>
  VTKM_EXEC_CONT void SetToPortals(vtkm::Id index, const ValueType& value, const Portals&... portals)
  {
    SetToPortalsImpl(
      index,
      value,
      vtkmstd::make_integer_sequence<vtkm::IdComponent, vtkm::IdComponent(sizeof...(Portals))>{},
      portals...);
  }
  
  } // end namespace compvec
  
  template <typename... PortalTypes>
  class VTKM_ALWAYS_EXPORT ArrayPortalCompositeVector
  {
    using Writable = compvec::AllPortalsAreWritable<PortalTypes...>;
    using TupleType = vtkm::Tuple<PortalTypes...>;
    TupleType Portals;
  
  public:
    using ValueType = typename compvec::GetValueType<PortalTypes...>::ValueType;
  
    VTKM_EXEC_CONT
    ArrayPortalCompositeVector() {}
  
    VTKM_CONT
    ArrayPortalCompositeVector(const PortalTypes&... portals)
      : Portals(portals...)
    {
    }
  
    VTKM_CONT
    ArrayPortalCompositeVector(const TupleType& portals)
      : Portals(portals)
    {
    }
  
    VTKM_EXEC_CONT
    vtkm::Id GetNumberOfValues() const { return vtkm::Get<0>(this->Portals).GetNumberOfValues(); }
  
    VTKM_EXEC_CONT
    ValueType Get(vtkm::Id index) const
    {
      return this->Portals.Apply(compvec::GetFromPortals<PortalTypes...>, index);
    }
  
    template <typename Writable_ = Writable,
              typename = typename std::enable_if<Writable_::value>::type>
    VTKM_EXEC_CONT void Set(vtkm::Id index, const ValueType& value) const
    {
      this->Portals.Apply(compvec::SetToPortals<ValueType, PortalTypes...>, index, value);
    }
  };
  
  } // namespace internal
  
  template <typename... StorageTags>
  struct VTKM_ALWAYS_EXPORT StorageTagCompositeVec
  {
  };
  
  namespace internal
  {
  
  template <typename... ArrayTs>
  struct CompositeVectorTraits
  {
    // Need to check this here, since this traits struct is used in the
    // ArrayHandleCompositeVector superclass definition before any other
    // static_asserts could be used.
    VTKM_STATIC_ASSERT_MSG(compvec::AllAreArrayHandles<ArrayTs...>::Value,
                           "Template parameters for ArrayHandleCompositeVector "
                           "must be a list of ArrayHandle types.");
  
    using ValueType = typename compvec::GetValueType<ArrayTs...>::ValueType;
    using StorageTag = vtkm::cont::StorageTagCompositeVec<typename ArrayTs::StorageTag...>;
    using StorageType = Storage<ValueType, StorageTag>;
    using Superclass = ArrayHandle<ValueType, StorageTag>;
  };
  
  template <typename T, typename... StorageTags>
  class Storage<vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(StorageTags))>,
                vtkm::cont::StorageTagCompositeVec<StorageTags...>>
  {
    using ArrayTuple = vtkm::Tuple<vtkm::cont::ArrayHandle<T, StorageTags>...>;
  
    ArrayTuple Arrays;
    bool Valid;
  
  public:
    using ValueType = vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(StorageTags))>;
    using PortalType = ArrayPortalCompositeVector<
      typename vtkm::cont::ArrayHandle<T, StorageTags>::WritePortalType...>;
    using PortalConstType =
      ArrayPortalCompositeVector<typename vtkm::cont::ArrayHandle<T, StorageTags>::ReadPortalType...>;
  
    VTKM_CONT
    Storage()
      : Valid(false)
    {
    }
  
    template <typename... ArrayTypes>
    VTKM_CONT Storage(const ArrayTypes&... arrays)
      : Arrays(arrays...)
      , Valid(true)
    {
      using SizeValidator = compvec::ArraySizeValidator<ArrayTuple>;
      if (!SizeValidator::Exec(this->Arrays, this->GetNumberOfValues()))
      {
        throw ErrorBadValue("All arrays must have the same number of values.");
      }
    }
  
    VTKM_CONT
    PortalType GetPortal()
    {
      VTKM_ASSERT(this->Valid);
      return this->Arrays.Transform(compvec::WritePortal{});
    }
  
    void TypeCheck(int) const;
    VTKM_CONT
    PortalConstType GetPortalConst() const
    {
      VTKM_ASSERT(this->Valid);
      this->Arrays.Transform(compvec::ReadPortal{});
      return this->Arrays.Transform(compvec::ReadPortal{});
    }
  
    VTKM_CONT
    vtkm::Id GetNumberOfValues() const
    {
      VTKM_ASSERT(this->Valid);
      return vtkm::Get<0>(this->Arrays).GetNumberOfValues();
    }
  
    VTKM_CONT
    void Allocate(vtkm::Id numValues)
    {
      VTKM_ASSERT(this->Valid);
      this->Arrays.ForEach(compvec::Allocate{ numValues });
    }
  
    VTKM_CONT
    void Shrink(vtkm::Id numValues)
    {
      VTKM_ASSERT(this->Valid);
      this->Arrays.ForEach(compvec::Shrink{ numValues });
    }
  
    VTKM_CONT
    void ReleaseResources()
    {
      VTKM_ASSERT(this->Valid);
      this->Arrays.ForEach(compvec::ReleaseResources{});
    }
  
    VTKM_CONT
    const ArrayTuple& GetArrayTuple() const
    {
      VTKM_ASSERT(this->Valid);
      return this->Arrays;
    }
  
    VTKM_CONT
    ArrayTuple& GetArrayTuple()
    {
      VTKM_ASSERT(this->Valid);
      return this->Arrays;
    }
  };
  
  // Special case for single component. Just defer to the original storage.
  template <typename T, typename StorageTag>
  class Storage<T, vtkm::cont::StorageTagCompositeVec<StorageTag>> : public Storage<T, StorageTag>
  {
    using ArrayType = vtkm::cont::ArrayHandle<T, StorageTag>;
    using TupleType = vtkm::Tuple<ArrayType>;
  
  public:
    Storage() = default;
    Storage(const ArrayType& array)
      : Storage<T, StorageTag>(array.GetStorage())
    {
    }
  
    VTKM_CONT
    const TupleType GetArrayTuple() const { return TupleType(ArrayType(this->GetStoragea())); }
  };
  
  template <typename T, typename... StorageTags, typename DeviceTag>
  class ArrayTransfer<vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(StorageTags))>,
                      vtkm::cont::StorageTagCompositeVec<StorageTags...>,
                      DeviceTag>
  {
    VTKM_IS_DEVICE_ADAPTER_TAG(DeviceTag);
  
    using ArrayTuple = vtkm::Tuple<vtkm::cont::ArrayHandle<T, StorageTags>...>;
  
  public:
    using ValueType = vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(StorageTags))>;
  
  private:
    using StorageTag = vtkm::cont::StorageTagCompositeVec<StorageTags...>;
    using StorageType = internal::Storage<ValueType, StorageTag>;
  
    StorageType* Storage;
  
  public:
    using PortalControl = typename StorageType::PortalType;
    using PortalConstControl = typename StorageType::PortalConstType;
  
    using PortalExecution =
      ArrayPortalCompositeVector<typename vtkm::cont::ArrayHandle<T, StorageTags>::
                                   template ExecutionTypes<DeviceTag>::Portal...>;
    using PortalConstExecution =
      ArrayPortalCompositeVector<typename vtkm::cont::ArrayHandle<T, StorageTags>::
                                   template ExecutionTypes<DeviceTag>::PortalConst...>;
  
    VTKM_CONT
    ArrayTransfer(StorageType* storage)
      : Storage(storage)
    {
    }
  
    VTKM_CONT
    vtkm::Id GetNumberOfValues() const { return this->Storage->GetNumberOfValues(); }
  
    VTKM_CONT
    PortalConstExecution PrepareForInput(bool vtkmNotUsed(updateData), vtkm::cont::Token& token) const
    {
      return this->GetArrayTuple().Transform(compvec::PrepareForInput<DeviceTag>{ token });
    }
  
    VTKM_CONT
    PortalExecution PrepareForInPlace(bool vtkmNotUsed(updateData), vtkm::cont::Token& token)
    {
      return this->GetArrayTuple().Transform(compvec::PrepareForInPlace<DeviceTag>{ token });
    }
  
    VTKM_CONT
    PortalExecution PrepareForOutput(vtkm::Id numValues, vtkm::cont::Token& token)
    {
      return this->GetArrayTuple().Transform(
        compvec::PrepareForOutput<DeviceTag>{ numValues, token });
    }
  
    VTKM_CONT
    void RetrieveOutputData(StorageType* vtkmNotUsed(storage)) const
    {
      // Implementation of this method should be unnecessary. The internal
      // array handle should automatically retrieve the output data as
      // necessary.
    }
  
    VTKM_CONT
    void Shrink(vtkm::Id numValues) { this->GetArrayTuple().ForEach(compvec::Shrink{ numValues }); }
  
    VTKM_CONT
    void ReleaseResources() { this->GetArrayTuple().ForEach(compvec::ReleaseResourcesExecution{}); }
  
    VTKM_CONT
    const ArrayTuple& GetArrayTuple() const { return this->Storage->GetArrayTuple(); }
    ArrayTuple& GetArrayTuple() { return this->Storage->GetArrayTuple(); }
  };
  
  } // namespace internal
  
  /// \brief An \c ArrayHandle that combines components from other arrays.
  ///
  /// \c ArrayHandleCompositeVector is a specialization of \c ArrayHandle that
  /// derives its content from other arrays. It takes any number of
  /// single-component \c ArrayHandle objects and mimics an array that contains
  /// vectors with components that come from these delegate arrays.
  ///
  /// The easiest way to create and type an \c ArrayHandleCompositeVector is
  /// to use the \c make_ArrayHandleCompositeVector functions.
  ///
  /// The \c ArrayHandleExtractComponent class may be helpful when a desired
  /// component is part of an \c ArrayHandle with a \c vtkm::Vec \c ValueType.
  ///
  template <typename... ArrayTs>
  class ArrayHandleCompositeVector
    : public ArrayHandle<typename internal::CompositeVectorTraits<ArrayTs...>::ValueType,
                         typename internal::CompositeVectorTraits<ArrayTs...>::StorageTag>
  {
  private:
    using Traits = internal::CompositeVectorTraits<ArrayTs...>;
    using TupleType = vtkm::Tuple<ArrayTs...>;
    using StorageType = typename Traits::StorageType;
  
  public:
    VTKM_ARRAY_HANDLE_SUBCLASS(ArrayHandleCompositeVector,
                               (ArrayHandleCompositeVector<ArrayTs...>),
                               (typename Traits::Superclass));
  
    VTKM_CONT
    ArrayHandleCompositeVector(const ArrayTs&... arrays)
      : Superclass(StorageType(arrays...))
    {
    }
  };
  
  /// Create a composite vector array from other arrays.
  ///
  template <typename... ArrayTs>
  VTKM_CONT ArrayHandleCompositeVector<ArrayTs...> make_ArrayHandleCompositeVector(
    const ArrayTs&... arrays)
  {
    VTKM_STATIC_ASSERT_MSG(internal::compvec::AllAreArrayHandles<ArrayTs...>::Value,
                           "Arguments to make_ArrayHandleCompositeVector must be "
                           "of ArrayHandle types.");
    return ArrayHandleCompositeVector<ArrayTs...>(arrays...);
  }
  }
  } // namespace vtkm::cont
  
  //=============================================================================
  // Specializations of serialization related classes
  /// @cond SERIALIZATION
  namespace vtkm
  {
  namespace cont
  {
  
  template <typename... AHs>
  struct SerializableTypeString<vtkm::cont::ArrayHandleCompositeVector<AHs...>>
  {
    static VTKM_CONT const std::string& Get()
    {
      static std::string name =
        "AH_CompositeVector<" + internal::GetVariadicSerializableTypeString(AHs{}...) + ">";
      return name;
    }
  };
  
  template <typename T, typename... STs>
  struct SerializableTypeString<
    vtkm::cont::ArrayHandle<vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(STs))>,
                            vtkm::cont::StorageTagCompositeVec<STs...>>>
    : SerializableTypeString<
        vtkm::cont::ArrayHandleCompositeVector<vtkm::cont::ArrayHandle<T, STs>...>>
  {
  };
  }
  } // vtkm::cont
  
  namespace mangled_diy_namespace
  {
  
  template <typename... AHs>
  struct Serialization<vtkm::cont::ArrayHandleCompositeVector<AHs...>>
  {
  private:
    using Type = typename vtkm::cont::ArrayHandleCompositeVector<AHs...>;
    using BaseType = vtkm::cont::ArrayHandle<typename Type::ValueType, typename Type::StorageTag>;
  
    struct SaveFunctor
    {
      BinaryBuffer& Buffer;
      SaveFunctor(BinaryBuffer& bb)
        : Buffer(bb)
      {
      }
  
      template <typename AH>
      void operator()(const AH& ah) const
      {
        vtkmdiy::save(this->Buffer, ah);
      }
    };
  
    struct LoadFunctor
    {
      BinaryBuffer& Buffer;
      LoadFunctor(BinaryBuffer& bb)
        : Buffer(bb)
      {
      }
  
      template <typename AH>
      void operator()(AH& ah) const
      {
        vtkmdiy::load(this->Buffer, ah);
      }
    };
  
    static BaseType Create(const AHs&... arrays) { return Type(arrays...); }
  
  public:
    static VTKM_CONT void save(BinaryBuffer& bb, const BaseType& obj)
    {
      obj.GetStorage().GetArrayTuple().ForEach(SaveFunctor{ bb });
    }
  
    static VTKM_CONT void load(BinaryBuffer& bb, BaseType& obj)
    {
      vtkm::Tuple<AHs...> tuple;
      tuple.ForEach(LoadFunctor{ bb });
      obj = tuple.Apply(Create);
    }
  };
  
  template <typename T, typename... STs>
  struct Serialization<
    vtkm::cont::ArrayHandle<vtkm::Vec<T, static_cast<vtkm::IdComponent>(sizeof...(STs))>,
                            vtkm::cont::StorageTagCompositeVec<STs...>>>
    : Serialization<vtkm::cont::ArrayHandleCompositeVector<vtkm::cont::ArrayHandle<T, STs>...>>
  {
  };
  } // diy
  /// @endcond SERIALIZATION
  
  #endif //vtk_m_ArrayHandleCompositeVector_h
  