128 lines
4.1 KiB
C++
128 lines
4.1 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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// 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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// Copyright 2016 Sandia Corporation.
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// Copyright 2016 UT-Battelle, LLC.
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// Copyright 2016 Los Alamos National Security.
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//
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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#ifndef vtk_m_internal_ArrayPortalValueReference_h
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#define vtk_m_internal_ArrayPortalValueReference_h
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#include <vtkm/TypeTraits.h>
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#include <vtkm/Types.h>
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#include <vtkm/VecTraits.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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/// \brief A value class for returning setable values of an ArrayPortal
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///
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/// \c ArrayPortal classes have a pair of \c Get and \c Set methods that
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/// retreive and store values in the array. This is to make it easy to
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/// implement the \c ArrayPortal even it is not really an array. However, there
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/// are some cases where the code structure expects a reference to a value that
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/// can be set. For example, the \c IteratorFromArrayPortal class must return
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/// something from its * operator that behaves like a reference.
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///
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/// For cases of this nature \c ArrayPortalValueReference can be used. This
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/// class is constructured with an \c ArrayPortal and an index into the array.
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/// The object then behaves like a reference to the value in the array. If you
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/// set this reference object to a new value, it will call \c Set on the
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/// \c ArrayPortal to insert the value into the array.
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///
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template <typename ArrayPortalType>
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struct ArrayPortalValueReference
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{
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using ValueType = typename ArrayPortalType::ValueType;
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VTKM_SUPPRESS_EXEC_WARNINGS
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VTKM_EXEC_CONT
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ArrayPortalValueReference(const ArrayPortalType& portal, vtkm::Id index)
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: Portal(portal)
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, Index(index)
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{
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}
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VTKM_CONT
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void Swap(ArrayPortalValueReference<ArrayPortalType>& rhs) throw()
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{
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//we need use the explicit type not a proxy temp object
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//A proxy temp object would point to the same underlying data structure
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//and would not hold the old value of *this once *this was set to rhs.
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const ValueType aValue = *this;
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*this = rhs;
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rhs = aValue;
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}
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VTKM_SUPPRESS_EXEC_WARNINGS
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VTKM_EXEC_CONT
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ArrayPortalValueReference<ArrayPortalType>& operator=(
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const ArrayPortalValueReference<ArrayPortalType>& rhs)
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{
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this->Portal.Set(this->Index, rhs.Portal.Get(rhs.Index));
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return *this;
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}
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VTKM_SUPPRESS_EXEC_WARNINGS
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VTKM_EXEC_CONT
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ValueType operator=(const ValueType& value)
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{
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this->Portal.Set(this->Index, value);
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return value;
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}
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VTKM_SUPPRESS_EXEC_WARNINGS
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VTKM_EXEC_CONT
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operator ValueType(void) const { return this->Portal.Get(this->Index); }
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const ArrayPortalType& Portal;
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vtkm::Id Index;
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};
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//implement a custom swap function, since the std::swap won't work
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//since we return RValues instead of Lvalues
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template <typename T>
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void swap(vtkm::internal::ArrayPortalValueReference<T> a,
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vtkm::internal::ArrayPortalValueReference<T> b)
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{
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a.Swap(b);
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}
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}
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} // namespace vtkm::internal
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namespace vtkm
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{
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// Make specialization for TypeTraits and VecTraits so that the reference
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// behaves the same as the value.
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template <typename PortalType>
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struct TypeTraits<vtkm::internal::ArrayPortalValueReference<PortalType>>
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: vtkm::TypeTraits<typename vtkm::internal::ArrayPortalValueReference<PortalType>::ValueType>
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{
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};
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template <typename PortalType>
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struct VecTraits<vtkm::internal::ArrayPortalValueReference<PortalType>>
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: vtkm::VecTraits<typename vtkm::internal::ArrayPortalValueReference<PortalType>::ValueType>
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{
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};
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} // namespace vtkm
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#endif //vtk_m_internal_ArrayPortalValueReference_h
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