libstdc++: mask_array.h Source File

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mask_array.h
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1// The template and inlines for the -*- C++ -*- mask_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/mask_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 _MASK_ARRAY_H
33#define _MASK_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 selected subset of an array.
50 *
51 * A mask_array is a reference to the actual elements of an array specified
52 * by a bitmask in the form of an array of bool. The way to get a
53 * mask_array is to call operator[](valarray<bool>) on a valarray. The
54 * returned mask_array then permits carrying operations out on the
55 * referenced subset of elements in the original valarray.
56 *
57 * For example, if a mask_array is obtained using the array (false, true,
58 * false, true) as an argument, the mask array has two elements referring
59 * to array[1] and array[3] in the underlying array.
60 *
61 * @param Tp Element type.
62 */
63 template <class _Tp>
64 class mask_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 mask_array (const mask_array&);
74
75 /// Assignment operator. Assigns elements to corresponding elements
76 /// of @a a.
77 mask_array& operator=(const mask_array&);
78
79 void operator=(const valarray<_Tp>&) const;
80 /// Multiply slice elements by corresponding elements of @a v.
81 void operator*=(const valarray<_Tp>&) const;
82 /// Divide slice elements by corresponding elements of @a v.
83 void operator/=(const valarray<_Tp>&) const;
84 /// Modulo slice elements by corresponding elements of @a v.
85 void operator%=(const valarray<_Tp>&) const;
86 /// Add corresponding elements of @a v to slice elements.
87 void operator+=(const valarray<_Tp>&) const;
88 /// Subtract corresponding elements of @a v from slice elements.
89 void operator-=(const valarray<_Tp>&) const;
90 /// Logical xor slice elements with corresponding elements of @a v.
91 void operator^=(const valarray<_Tp>&) const;
92 /// Logical and slice elements with corresponding elements of @a v.
93 void operator&=(const valarray<_Tp>&) const;
94 /// Logical or slice elements with corresponding elements of @a v.
95 void operator|=(const valarray<_Tp>&) const;
96 /// Left shift slice elements by corresponding elements of @a v.
97 void operator<<=(const valarray<_Tp>&) const;
98 /// Right shift slice elements by corresponding elements of @a v.
99 void operator>>=(const valarray<_Tp>&) const;
100 /// Assign all slice elements to @a t.
101 void operator=(const _Tp&) const;
102
103 // ~mask_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 mask_array(_Array<_Tp>, size_t, _Array<bool>);
130 friend class valarray<_Tp>;
131
132 const size_t _M_sz;
133 const _Array<bool> _M_mask;
134 const _Array<_Tp> _M_array;
135
136#if __cplusplus < 201103L
137 // not implemented
138 mask_array();
139#else
140 public:
141 mask_array() = delete;
142#endif
143 };
144
145 template<typename _Tp>
146 inline mask_array<_Tp>::mask_array(const mask_array<_Tp>& __a)
147 : _M_sz(__a._M_sz), _M_mask(__a._M_mask), _M_array(__a._M_array) {}
148
149 template<typename _Tp>
150 inline
151 mask_array<_Tp>::mask_array(_Array<_Tp> __a, size_t __s, _Array<bool> __m)
152 : _M_sz(__s), _M_mask(__m), _M_array(__a) {}
153
154 template<typename _Tp>
155 inline mask_array<_Tp>&
156 mask_array<_Tp>::operator=(const mask_array<_Tp>& __a)
157 {
158 __glibcxx_assert(__a._M_sz == _M_sz);
159 std::__valarray_copy(__a._M_array, __a._M_mask,
160 _M_sz, _M_array, _M_mask);
161 return *this;
162 }
163
164 template<typename _Tp>
165 inline void
166 mask_array<_Tp>::operator=(const _Tp& __t) const
167 { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }
168
169 template<typename _Tp>
170 inline void
171 mask_array<_Tp>::operator=(const valarray<_Tp>& __v) const
172 {
173 __glibcxx_assert(__v.size() == _M_sz);
174 std::__valarray_copy(_Array<_Tp>(__v), __v.size(), _M_array, _M_mask);
175 }
176
177 template<typename _Tp>
178 template<class _Ex>
179 inline void
180 mask_array<_Tp>::operator=(const _Expr<_Ex, _Tp>& __e) const
181 {
182 __glibcxx_assert(__e.size() == _M_sz);
183 std::__valarray_copy(__e, __e.size(), _M_array, _M_mask);
184 }
185
186 /// @cond undocumented
187#undef _DEFINE_VALARRAY_OPERATOR
188#define _DEFINE_VALARRAY_OPERATOR(_Op, _Name) \
189 template<typename _Tp> \
190 inline void \
191 mask_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const \
192 { \
193 __glibcxx_assert(__v.size() == _M_sz); \
194 _Array_augmented_##_Name(_M_array, _M_mask, \
195 _Array<_Tp>(__v), __v.size()); \
196 } \
197 \
198 template<typename _Tp> \
199 template<class _Dom> \
200 inline void \
201 mask_array<_Tp>::operator _Op##=(const _Expr<_Dom, _Tp>& __e) const\
202 { \
203 __glibcxx_assert(__e.size() == _M_sz); \
204 _Array_augmented_##_Name(_M_array, _M_mask, __e, __e.size()); \
205 }
206
207_DEFINE_VALARRAY_OPERATOR(*, __multiplies)
208_DEFINE_VALARRAY_OPERATOR(/, __divides)
209_DEFINE_VALARRAY_OPERATOR(%, __modulus)
210_DEFINE_VALARRAY_OPERATOR(+, __plus)
211_DEFINE_VALARRAY_OPERATOR(-, __minus)
212_DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
213_DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
214_DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
215_DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
216_DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
217
218#undef _DEFINE_VALARRAY_OPERATOR
219 /// @endcond
220
221 /// @} group numeric_arrays
222
223_GLIBCXX_END_NAMESPACE_VERSION
224} // namespace
225
226#endif /* _MASK_ARRAY_H */
std::valarray::size
size_t size() const
Return the number of elements in array.
Definition valarray:988
std::mask_array::mask_array
mask_array(const mask_array &)
Copy constructor. Both slices refer to the same underlying array.
Definition mask_array.h:146
std::mask_array::operator=
mask_array & operator=(const mask_array &)
Assignment operator. Assigns elements to corresponding elements of a.
Definition mask_array.h:156
std
ISO C++ entities toplevel namespace is std.
std::valarray
Smart array designed to support numeric processing.
Definition valarray:137
std::mask_array::operator*=
void operator*=(const valarray< _Tp > &) const
Multiply slice elements by corresponding elements of v.
std::mask_array::operator+=
void operator+=(const valarray< _Tp > &) const
Add corresponding elements of v to slice elements.
std::mask_array::operator&=
void operator&=(const valarray< _Tp > &) const
Logical and slice elements with corresponding elements of v.
std::mask_array::operator|=
void operator|=(const valarray< _Tp > &) const
Logical or slice elements with corresponding elements of v.
std::mask_array::operator-=
void operator-=(const valarray< _Tp > &) const
Subtract corresponding elements of v from slice elements.
std::mask_array::operator>>=
void operator>>=(const valarray< _Tp > &) const
Right shift slice elements by corresponding elements of v.
std::mask_array::operator%=
void operator%=(const valarray< _Tp > &) const
Modulo slice elements by corresponding elements of v.
std::mask_array::operator^=
void operator^=(const valarray< _Tp > &) const
Logical xor slice elements with corresponding elements of v.
std::mask_array::operator/=
void operator/=(const valarray< _Tp > &) const
Divide slice elements by corresponding elements of v.
std::mask_array::operator<<=
void operator<<=(const valarray< _Tp > &) const
Left shift slice elements by corresponding elements of v.