7e01edb017
This patch removes (or conditionally removes) the Set method from portals that are read-only so that IsWritableArrayHandle will work as expected. The ArrayPortal doxygen has been updated to reflect this. The remaining exceptions are `ArrayPortalVirtual` and `ArrayPortalMultiplexer`, since their mutability cannot be determined at compile time.
85 lines
3.0 KiB
C++
85 lines
3.0 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_cont_ArrayPortal_h
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#define vtk_m_cont_ArrayPortal_h
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#include <vtkm/Types.h>
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namespace vtkm
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{
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namespace cont
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{
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#ifdef VTKM_DOXYGEN_ONLY
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/// \brief A class that points to and access and array of data.
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///
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/// The ArrayPortal class itself does not exist; this code is provided for
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/// documentation purposes only.
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///
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/// An ArrayPortal object acts like a pointer to a random-access container
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/// (that is, an array) and also lets you set and get values in that array. In
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/// many respects an ArrayPortal is similar in concept to that of iterators but
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/// with a much simpler interface and no internal concept of position.
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/// Otherwise, ArrayPortal objects may be passed and copied around so that
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/// multiple entities may be accessing the same array.
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///
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/// An ArrayPortal differs from an ArrayHandle in that the ArrayPortal is a
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/// much lighterweight object and that it does not manage things like
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/// allocation and control/execution sharing. An ArrayPortal also differs from
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/// a Storage in that it does not actually contain the data but rather
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/// points to it. In this way the ArrayPortal can be copied and passed and
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/// still point to the same data.
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///
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/// Most VTKm users generally do not need to do much or anything with
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/// ArrayPortal objects. It is mostly an internal mechanism. However, an
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/// ArrayPortal can be used to pass constant input data to an ArrayHandle.
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///
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/// Although portals are defined in the execution environment, they are also
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/// used in the control environment for accessing data on the host.
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///
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/// Since utilities like IsWritableArrayHandle checks for the existence of a Set
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/// method on a portal, if the portal is backed by a read-only ArrayHandle, the
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/// Set method must not be defined. If the portal may or may not be writable
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/// (e.g., ArrayHandleCast may be casting a read-only OR read-write array), the
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/// Set method may be conditionally removed using SFINAE.
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///
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template <typename T>
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class ArrayPortal
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{
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public:
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/// The type of each value in the array.
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///
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using ValueType = T;
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/// The total number of values in the array. They are index from 0 to
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/// GetNumberOfValues()-1.
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///
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VTKM_EXEC_CONT
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vtkm::Id GetNumberOfValues() const;
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/// Gets a value from the array.
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///
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VTKM_EXEC_CONT
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ValueType Get(vtkm::Id index) const;
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/// Sets a value in the array. If it is not possible to set a value in the
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/// array, this method must not be defined.
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///
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VTKM_EXEC_CONT
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void Set(vtkm::Id index, const ValueType& value) const;
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};
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#endif // VTKM_DOXYGEN_ONLY
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}
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} // namespace vtkm::cont
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#endif //vtk_m_cont_ArrayPortal_h
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