src/gromacs/mdspan/extensions.h

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  35 /*! \libinternal
  36  * \file
  37  * \brief GROMACS extensions to mdspan.
  38  *
  39  * \author Christian Blau <cblau@gwdg.de>
  40  * \inlibraryapi
  41  * \ingroup module_mdspan
  42  */
  43
  44 #ifndef GMX_MDSPAN_EXTENSIONS_H_
  45 #define GMX_MDSPAN_EXTENSIONS_H_
  46
  47 #include <algorithm>
  48 #include <functional>
  49
  50 #include "gromacs/mdspan/mdspan.h"
  51
  52 namespace gmx
  53 {
  54
  55 /*! \brief
  56  * Free begin function addressing memory of a contiguously laid out basic_mdspan.
  57  *
  58  * \note Changing the elements that basic_mdspan views does not change
  59  *       the view itself, so a single begin that takes a const view suffices.
  60  */
  61 template<class BasicMdspan>
  62 constexpr std::enable_if_t<BasicMdspan::is_always_contiguous(), typename BasicMdspan::pointer>
  63 begin(const BasicMdspan& basicMdspan)
  64 {
  65     return basicMdspan.data();
  66 }
  67
  68 /*! \brief
  69  * Free end function addressing memory of a contiguously laid out basic_mdspan.
  70  *
  71  * \note Changing the elements that basic_mdspan views does not change
  72  *       the view itself, so a single end that takes a const view suffices.
  73  */
  74 template<class BasicMdspan>
  75 constexpr std::enable_if_t<BasicMdspan::is_always_contiguous(), typename BasicMdspan::pointer>
  76 end(const BasicMdspan& basicMdspan)
  77 {
  78     return basicMdspan.data() + basicMdspan.mapping().required_span_size();
  79 }
  80
  81 //! Convenience type for often-used two dimensional extents
  82 using dynamicExtents2D = extents<dynamic_extent, dynamic_extent>;
  83
  84 //! Convenience type for often-used three dimensional extents
  85 using dynamicExtents3D = extents<dynamic_extent, dynamic_extent, dynamic_extent>;
  86
  87 //! Elementwise addition
  88 template<class BasicMdspan>
  89 constexpr BasicMdspan addElementwise(const BasicMdspan& span1, const BasicMdspan& span2)
  90 {
  91     BasicMdspan result(span1);
  92     std::transform(begin(span1), end(span1), begin(span2), begin(result),
  93                    std::plus<typename BasicMdspan::element_type>());
  94     return result;
  95 }
  96
  97 //! Elementwise subtraction - left minus right
  98 template<class BasicMdspan>
  99 constexpr BasicMdspan subtractElementwise(const BasicMdspan& span1, const BasicMdspan& span2)
 100 {
 101     BasicMdspan result(span1);
 102     std::transform(begin(span1), end(span1), begin(span2), begin(result),
 103                    std::minus<typename BasicMdspan::element_type>());
 104     return result;
 105 }
 106
 107 //! Elementwise multiplication
 108 template<class BasicMdspan>
 109 constexpr BasicMdspan multiplyElementwise(const BasicMdspan& span1, const BasicMdspan& span2)
 110 {
 111     BasicMdspan result(span1);
 112     std::transform(begin(span1), end(span1), begin(span2), begin(result),
 113                    std::multiplies<typename BasicMdspan::element_type>());
 114     return result;
 115 }
 116
 117 //! Elementwise division - left / right
 118 template<class BasicMdspan>
 119 constexpr BasicMdspan divideElementwise(const BasicMdspan& span1, const BasicMdspan& span2)
 120 {
 121     BasicMdspan result(span1);
 122     std::transform(begin(span1), end(span1), begin(span2), begin(result),
 123                    std::divides<typename BasicMdspan::element_type>());
 124     return result;
 125 }
 126
 127 } // namespace gmx
 128
 129 #endif // GMX_MDSPAN_EXTENSIONS_H_