1 // The template and inlines for the -*- C++ -*- indirect_array class.
2
3 // Copyright (C) 1997-2023 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 #pragma GCC system_header
36
37 namespace std _GLIBCXX_VISIBILITY(default)
38 {
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41 /**
42 * @addtogroup numeric_arrays
43 * @{
44 */
45
46 /**
47 * @brief Reference to arbitrary subset of an array.
48 *
49 * An indirect_array is a reference to the actual elements of an array
50 * specified by an ordered array of indices. The way to get an
51 * indirect_array is to call operator[](valarray<size_t>) on a valarray.
52 * The returned indirect_array then permits carrying operations out on the
53 * referenced subset of elements in the original valarray.
54 *
55 * For example, if an indirect_array is obtained using the array (4,2,0) as
56 * an argument, and then assigned to an array containing (1,2,3), then the
57 * underlying array will have array[0]==3, array[2]==2, and array[4]==1.
58 *
59 * @param Tp Element type.
60 */
61 template <class _Tp>
62 class indirect_array
63 {
64 public:
65 typedef _Tp value_type;
66
67 // _GLIBCXX_RESOLVE_LIB_DEFECTS
68 // 253. valarray helper functions are almost entirely useless
69
70 /// Copy constructor. Both slices refer to the same underlying array.
71 indirect_array(const indirect_array&);
72
73 /// Assignment operator. Assigns elements to corresponding elements
74 /// of @a a.
75 indirect_array& operator=(const indirect_array&);
76
77 /// Assign slice elements to corresponding elements of @a v.
78 void operator=(const valarray<_Tp>&) const;
79 /// Multiply slice elements by corresponding elements of @a v.
80 void operator*=(const valarray<_Tp>&) const;
81 /// Divide slice elements by corresponding elements of @a v.
82 void operator/=(const valarray<_Tp>&) const;
83 /// Modulo slice elements by corresponding elements of @a v.
84 void operator%=(const valarray<_Tp>&) const;
85 /// Add corresponding elements of @a v to slice elements.
86 void operator+=(const valarray<_Tp>&) const;
87 /// Subtract corresponding elements of @a v from slice elements.
88 void operator-=(const valarray<_Tp>&) const;
89 /// Logical xor slice elements with corresponding elements of @a v.
90 void operator^=(const valarray<_Tp>&) const;
91 /// Logical and slice elements with corresponding elements of @a v.
92 void operator&=(const valarray<_Tp>&) const;
93 /// Logical or slice elements with corresponding elements of @a v.
94 void operator|=(const valarray<_Tp>&) const;
95 /// Left shift slice elements by corresponding elements of @a v.
96 void operator<<=(const valarray<_Tp>&) const;
97 /// Right shift slice elements by corresponding elements of @a v.
98 void operator>>=(const valarray<_Tp>&) const;
99 /// Assign all slice elements to @a t.
100 void operator= (const _Tp&) const;
101 // ~indirect_array();
102
103 template<class _Dom>
104 void operator=(const _Expr<_Dom, _Tp>&) const;
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
126 private:
127 /// Copy constructor. Both slices refer to the same underlying array.
128 indirect_array(_Array<_Tp>, size_t, _Array<size_t>);
129
130 friend class valarray<_Tp>;
131 friend class gslice_array<_Tp>;
132
133 const size_t _M_sz;
134 const _Array<size_t> _M_index;
135 const _Array<_Tp> _M_array;
136
137 // not implemented
138 indirect_array();
139 };
140
141 template<typename _Tp>
142 inline
143 indirect_array<_Tp>::indirect_array(const indirect_array<_Tp>& __a)
144 : _M_sz(__a._M_sz), _M_index(__a._M_index), _M_array(__a._M_array) {}
145
146 template<typename _Tp>
147 inline
148 indirect_array<_Tp>::indirect_array(_Array<_Tp> __a, size_t __s,
149 _Array<size_t> __i)
150 : _M_sz(__s), _M_index(__i), _M_array(__a) {}
151
152 template<typename _Tp>
153 inline indirect_array<_Tp>&
154 indirect_array<_Tp>::operator=(const indirect_array<_Tp>& __a)
155 {
156 std::__valarray_copy(__a._M_array, _M_sz, __a._M_index, _M_array,
157 _M_index);
158 return *this;
159 }
160
161 template<typename _Tp>
162 inline void
163 indirect_array<_Tp>::operator=(const _Tp& __t) const
164 { std::__valarray_fill(_M_array, _M_index, _M_sz, __t); }
165
166 template<typename _Tp>
167 inline void
168 indirect_array<_Tp>::operator=(const valarray<_Tp>& __v) const
169 { std::__valarray_copy(_Array<_Tp>(__v), _M_sz, _M_array, _M_index); }
170
171 template<typename _Tp>
172 template<class _Dom>
173 inline void
174 indirect_array<_Tp>::operator=(const _Expr<_Dom, _Tp>& __e) const
175 { std::__valarray_copy(__e, _M_sz, _M_array, _M_index); }
176
177 /// @cond undocumented
178 #undef _DEFINE_VALARRAY_OPERATOR
179 #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name) \
180 template<typename _Tp> \
181 inline void \
182 indirect_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const\
183 { \
184 _Array_augmented_##_Name(_M_array, _M_index, _Array<_Tp>(__v), _M_sz); \
185 } \
186 \
187 template<typename _Tp> \
188 template<class _Dom> \
189 inline void \
190 indirect_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
191 { \
192 _Array_augmented_##_Name(_M_array, _M_index, __e, _M_sz); \
193 }
194
195 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
196 _DEFINE_VALARRAY_OPERATOR(/, __divides)
197 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
198 _DEFINE_VALARRAY_OPERATOR(+, __plus)
199 _DEFINE_VALARRAY_OPERATOR(-, __minus)
200 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
201 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
202 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
203 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
204 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
205
206 #undef _DEFINE_VALARRAY_OPERATOR
207 /// @endcond
208
209 /// @} group numeric_arrays
210
211 _GLIBCXX_END_NAMESPACE_VERSION
212 } // namespace
213
214 #endif /* _INDIRECT_ARRAY_H */