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(),
  63                            typename BasicMdspan::pointer>
  64 begin(const BasicMdspan &basicMdspan)
  65 {
  66     return basicMdspan.data();
  67 }
  68
  69 /*! \brief
  70  * Free end function addressing memory of a contiguously laid out basic_mdspan.
  71  *
  72  * \note Changing the elements that basic_mdspan views does not change
  73  *       the view itself, so a single end that takes a const view suffices.
  74  */
  75 template <class BasicMdspan>
  76 constexpr std::enable_if_t<BasicMdspan::is_always_contiguous(),
  77                            typename BasicMdspan::pointer>
  78 end(const BasicMdspan &basicMdspan)
  79 {
  80     return basicMdspan.data() + basicMdspan.mapping().required_span_size();
  81 }
  82
  83 //! Convenience type for often-used three dimensional extents
  84 using dynamicExtents3D = extents<dynamic_extent, dynamic_extent, dynamic_extent>;
  85
  86 //! Elementwise addition
  87 template <class BasicMdspan>
  88 constexpr BasicMdspan addElementwise(const BasicMdspan &span1, const BasicMdspan &span2)
  89 {
  90     BasicMdspan result(span1);
  91     std::transform(begin(span1), end(span1), begin(span2),
  92                    begin(result), std::plus<typename BasicMdspan::element_type>());
  93     return result;
  94 }
  95
  96 //! Elementwise subtraction - left minus right
  97 template <class BasicMdspan>
  98 constexpr BasicMdspan subtractElementwise(const BasicMdspan &span1, const BasicMdspan &span2)
  99 {
 100     BasicMdspan result(span1);
 101     std::transform(begin(span1), end(span1), begin(span2),
 102                    begin(result), std::minus<typename BasicMdspan::element_type>());
 103     return result;
 104 }
 105
 106 //! Elementwise multiplication
 107 template <class BasicMdspan>
 108 constexpr BasicMdspan multiplyElementwise(const BasicMdspan &span1, const BasicMdspan &span2)
 109 {
 110     BasicMdspan result(span1);
 111     std::transform(begin(span1), end(span1), begin(span2),
 112                    begin(result), std::multiplies<typename BasicMdspan::element_type>());
 113     return result;
 114 }
 115
 116 //! Elementwise division - left / right
 117 template <class BasicMdspan>
 118 constexpr BasicMdspan divideElementwise(const BasicMdspan &span1, const BasicMdspan &span2)
 119 {
 120     BasicMdspan result(span1);
 121     std::transform(begin(span1), end(span1), begin(span2),
 122                    begin(result), std::divides<typename BasicMdspan::element_type>());
 123     return result;
 124 }
 125
 126 }      // namespace gmx
 127
 128 #endif // GMX_MDSPAN_EXTENSIONS_H_