libstdc++: indirect_array.h Source File

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indirect_array.h
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1// The template and inlines for the -*- C++ -*- indirect_array class.
2
3// Copyright (C) 1997-2026 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
39namespace 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 */
std::indirect_array::operator=
indirect_array & operator=(const indirect_array &)
Assignment operator. Assigns elements to corresponding elements of a.
Definition indirect_array.h:156
std::indirect_array::indirect_array
indirect_array(const indirect_array &)
Copy constructor. Both slices refer to the same underlying array.
Definition indirect_array.h:145
std
ISO C++ entities toplevel namespace is std.
std::valarray
Smart array designed to support numeric processing.
Definition valarray:133
std::gslice_array
Reference to multi-dimensional subset of an array.
Definition gslice_array.h:63
std::indirect_array::operator/=
void operator/=(const valarray< _Tp > &) const
Divide slice elements by corresponding elements of v.
std::indirect_array::operator^=
void operator^=(const valarray< _Tp > &) const
Logical xor slice elements with corresponding elements of v.
std::indirect_array::operator|=
void operator|=(const valarray< _Tp > &) const
Logical or slice elements with corresponding elements of v.
std::indirect_array::operator<<=
void operator<<=(const valarray< _Tp > &) const
Left shift slice elements by corresponding elements of v.
std::indirect_array::operator>>=
void operator>>=(const valarray< _Tp > &) const
Right shift slice elements by corresponding elements of v.
std::indirect_array::operator-=
void operator-=(const valarray< _Tp > &) const
Subtract corresponding elements of v from slice elements.
std::indirect_array::operator*=
void operator*=(const valarray< _Tp > &) const
Multiply slice elements by corresponding elements of v.
std::indirect_array::operator&=
void operator&=(const valarray< _Tp > &) const
Logical and slice elements with corresponding elements of v.
std::indirect_array::operator+=
void operator+=(const valarray< _Tp > &) const
Add corresponding elements of v to slice elements.
std::indirect_array::operator%=
void operator%=(const valarray< _Tp > &) const
Modulo slice elements by corresponding elements of v.