libstdc++-v3/include/bits/indirect_array.h

   1 // The template and inlines for the -*- C++ -*- indirect_array class.
   2
   3 // Copyright (C) 1997-2025 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/indirect_array.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{valarray}
  28  */
  29
  30 // Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
  31
  32 #ifndef _INDIRECT_ARRAY_H
  33 #define _INDIRECT_ARRAY_H 1
  34
  35 #ifdef _GLIBCXX_SYSHDR
  36 #pragma GCC system_header
  37 #endif
  38
  39 namespace std _GLIBCXX_VISIBILITY(default)
  40 {
  41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  42
  43   /**
  44    * @addtogroup numeric_arrays
  45    * @{
  46    */
  47
  48   /**
  49    *  @brief  Reference to arbitrary subset of an array.
  50    *
  51    *  An indirect_array is a reference to the actual elements of an array
  52    *  specified by an ordered array of indices.  The way to get an
  53    *  indirect_array is to call operator[](valarray<size_t>) on a valarray.
  54    *  The returned indirect_array then permits carrying operations out on the
  55    *  referenced subset of elements in the original valarray.
  56    *
  57    *  For example, if an indirect_array is obtained using the array (4,2,0) as
  58    *  an argument, and then assigned to an array containing (1,2,3), then the
  59    *  underlying array will have array[0]==3, array[2]==2, and array[4]==1.
  60    *
  61    *  @param  Tp  Element type.
  62    */
  63   template <class _Tp>
  64     class indirect_array
  65     {
  66     public:
  67       typedef _Tp value_type;
  68
  69       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  70       // 253. valarray helper functions are almost entirely useless
  71
  72       ///  Copy constructor.  Both slices refer to the same underlying array.
  73       indirect_array(const indirect_array&);
  74
  75       ///  Assignment operator.  Assigns elements to corresponding elements
  76       ///  of @a a.
  77       indirect_array& operator=(const indirect_array&);
  78
  79       ///  Assign slice elements to corresponding elements of @a v.
  80       void operator=(const valarray<_Tp>&) const;
  81       ///  Multiply slice elements by corresponding elements of @a v.
  82       void operator*=(const valarray<_Tp>&) const;
  83       ///  Divide slice elements by corresponding elements of @a v.
  84       void operator/=(const valarray<_Tp>&) const;
  85       ///  Modulo slice elements by corresponding elements of @a v.
  86       void operator%=(const valarray<_Tp>&) const;
  87       ///  Add corresponding elements of @a v to slice elements.
  88       void operator+=(const valarray<_Tp>&) const;
  89       ///  Subtract corresponding elements of @a v from slice elements.
  90       void operator-=(const valarray<_Tp>&) const;
  91       ///  Logical xor slice elements with corresponding elements of @a v.
  92       void operator^=(const valarray<_Tp>&) const;
  93       ///  Logical and slice elements with corresponding elements of @a v.
  94       void operator&=(const valarray<_Tp>&) const;
  95       ///  Logical or slice elements with corresponding elements of @a v.
  96       void operator|=(const valarray<_Tp>&) const;
  97       ///  Left shift slice elements by corresponding elements of @a v.
  98       void operator<<=(const valarray<_Tp>&) const;
  99       ///  Right shift slice elements by corresponding elements of @a v.
 100       void operator>>=(const valarray<_Tp>&) const;
 101       ///  Assign all slice elements to @a t.
 102       void operator= (const _Tp&) const;
 103       //    ~indirect_array();
 104
 105       template<class _Dom>
 106       void operator=(const _Expr<_Dom, _Tp>&) const;
 107       template<class _Dom>
 108       void operator*=(const _Expr<_Dom, _Tp>&) const;
 109       template<class _Dom>
 110       void operator/=(const _Expr<_Dom, _Tp>&) const;
 111       template<class _Dom>
 112       void operator%=(const _Expr<_Dom, _Tp>&) const;
 113       template<class _Dom>
 114       void operator+=(const _Expr<_Dom, _Tp>&) const;
 115       template<class _Dom>
 116       void operator-=(const _Expr<_Dom, _Tp>&) const;
 117       template<class _Dom>
 118       void operator^=(const _Expr<_Dom, _Tp>&) const;
 119       template<class _Dom>
 120       void operator&=(const _Expr<_Dom, _Tp>&) const;
 121       template<class _Dom>
 122       void operator|=(const _Expr<_Dom, _Tp>&) const;
 123       template<class _Dom>
 124       void operator<<=(const _Expr<_Dom, _Tp>&) const;
 125       template<class _Dom>
 126       void operator>>=(const _Expr<_Dom, _Tp>&) const;
 127
 128     private:
 129       ///  Copy constructor.  Both slices refer to the same underlying array.
 130       indirect_array(_Array<_Tp>, size_t, _Array<size_t>);
 131
 132       friend class valarray<_Tp>;
 133       friend class gslice_array<_Tp>;
 134
 135       const size_t       _M_sz;
 136       const _Array<size_t> _M_index;
 137       const _Array<_Tp>  _M_array;
 138
 139       // not implemented
 140       indirect_array();
 141     };
 142
 143   template<typename _Tp>
 144     inline
 145     indirect_array<_Tp>::indirect_array(const indirect_array<_Tp>& __a)
 146     : _M_sz(__a._M_sz), _M_index(__a._M_index), _M_array(__a._M_array) {}
 147
 148   template<typename _Tp>
 149     inline
 150     indirect_array<_Tp>::indirect_array(_Array<_Tp> __a, size_t __s,
 151                                         _Array<size_t> __i)
 152     : _M_sz(__s), _M_index(__i), _M_array(__a) {}
 153
 154   template<typename _Tp>
 155     inline indirect_array<_Tp>&
 156     indirect_array<_Tp>::operator=(const indirect_array<_Tp>& __a)
 157     {
 158       std::__valarray_copy(__a._M_array, _M_sz, __a._M_index, _M_array,
 159                            _M_index);
 160       return *this;
 161     }
 162
 163   template<typename _Tp>
 164     inline void
 165     indirect_array<_Tp>::operator=(const _Tp& __t) const
 166     { std::__valarray_fill(_M_array, _M_index, _M_sz, __t); }
 167
 168   template<typename _Tp>
 169     inline void
 170     indirect_array<_Tp>::operator=(const valarray<_Tp>& __v) const
 171     { std::__valarray_copy(_Array<_Tp>(__v), _M_sz, _M_array, _M_index); }
 172
 173   template<typename _Tp>
 174     template<class _Dom>
 175       inline void
 176       indirect_array<_Tp>::operator=(const _Expr<_Dom, _Tp>& __e) const
 177       { std::__valarray_copy(__e, _M_sz, _M_array, _M_index); }
 178
 179   /// @cond undocumented
 180 #undef _DEFINE_VALARRAY_OPERATOR
 181 #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)                           \
 182   template<typename _Tp>                                                \
 183     inline void                                                         \
 184     indirect_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const\
 185     {                                                                   \
 186       _Array_augmented_##_Name(_M_array, _M_index, _Array<_Tp>(__v), _M_sz); \
 187     }                                                                   \
 188                                                                         \
 189   template<typename _Tp>                                                \
 190     template<class _Dom>                                                \
 191       inline void                                                       \
 192       indirect_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
 193       {                                                                 \
 194         _Array_augmented_##_Name(_M_array, _M_index, __e, _M_sz);       \
 195       }
 196
 197 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
 198 _DEFINE_VALARRAY_OPERATOR(/, __divides)
 199 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
 200 _DEFINE_VALARRAY_OPERATOR(+, __plus)
 201 _DEFINE_VALARRAY_OPERATOR(-, __minus)
 202 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
 203 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
 204 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
 205 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
 206 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
 207
 208 #undef _DEFINE_VALARRAY_OPERATOR
 209   /// @endcond
 210
 211   /// @} group numeric_arrays
 212
 213 _GLIBCXX_END_NAMESPACE_VERSION
 214 } // namespace
 215
 216 #endif /* _INDIRECT_ARRAY_H */