1 // The template and inlines for the -*- C++ -*- slice_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/slice_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 _SLICE_ARRAY_H
33 #define _SLICE_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 Class defining one-dimensional subset of an array.
48 *
49 * The slice class represents a one-dimensional subset of an array,
50 * specified by three parameters: start offset, size, and stride. The
51 * start offset is the index of the first element of the array that is part
52 * of the subset. The size is the total number of elements in the subset.
53 * Stride is the distance between each successive array element to include
54 * in the subset.
55 *
56 * For example, with an array of size 10, and a slice with offset 1, size 3
57 * and stride 2, the subset consists of array elements 1, 3, and 5.
58 */
59 class slice
60 {
61 public:
62 /// Construct an empty slice.
63 slice();
64
65 /**
66 * @brief Construct a slice.
67 *
68 * @param __o Offset in array of first element.
69 * @param __d Number of elements in slice.
70 * @param __s Stride between array elements.
71 */
72 slice(size_t __o, size_t __d, size_t __s);
73
74 /// Return array offset of first slice element.
75 size_t start() const;
76 /// Return size of slice.
77 size_t size() const;
78 /// Return array stride of slice.
79 size_t stride() const;
80
81 #if __cpp_impl_three_way_comparison >= 201907L
82 /// Equality comparison
83 friend bool operator==(const slice&, const slice&) = default;
84 #endif
85
86 private:
87 size_t _M_off; // offset
88 size_t _M_sz; // size
89 size_t _M_st; // stride unit
90 };
91
92 // _GLIBCXX_RESOLVE_LIB_DEFECTS
93 // 543. valarray slice default constructor
94 inline
95 slice::slice()
96 : _M_off(0), _M_sz(0), _M_st(0) {}
97
98 inline
99 slice::slice(size_t __o, size_t __d, size_t __s)
100 : _M_off(__o), _M_sz(__d), _M_st(__s) {}
101
102 inline size_t
103 slice::start() const
104 { return _M_off; }
105
106 inline size_t
107 slice::size() const
108 { return _M_sz; }
109
110 inline size_t
111 slice::stride() const
112 { return _M_st; }
113
114 /**
115 * @brief Reference to one-dimensional subset of an array.
116 *
117 * A slice_array is a reference to the actual elements of an array
118 * specified by a slice. The way to get a slice_array is to call
119 * operator[](slice) on a valarray. The returned slice_array then permits
120 * carrying operations out on the referenced subset of elements in the
121 * original valarray. For example, operator+=(valarray) will add values
122 * to the subset of elements in the underlying valarray this slice_array
123 * refers to.
124 *
125 * @param Tp Element type.
126 */
127 template<typename _Tp>
128 class slice_array
129 {
130 public:
131 typedef _Tp value_type;
132
133 // _GLIBCXX_RESOLVE_LIB_DEFECTS
134 // 253. valarray helper functions are almost entirely useless
135
136 /// Copy constructor. Both slices refer to the same underlying array.
137 slice_array(const slice_array&);
138
139 /// Assignment operator. Assigns slice elements to corresponding
140 /// elements of @a a.
141 slice_array& operator=(const slice_array&);
142
143 /// Assign slice elements to corresponding elements of @a v.
144 void operator=(const valarray<_Tp>&) const;
145 /// Multiply slice elements by corresponding elements of @a v.
146 void operator*=(const valarray<_Tp>&) const;
147 /// Divide slice elements by corresponding elements of @a v.
148 void operator/=(const valarray<_Tp>&) const;
149 /// Modulo slice elements by corresponding elements of @a v.
150 void operator%=(const valarray<_Tp>&) const;
151 /// Add corresponding elements of @a v to slice elements.
152 void operator+=(const valarray<_Tp>&) const;
153 /// Subtract corresponding elements of @a v from slice elements.
154 void operator-=(const valarray<_Tp>&) const;
155 /// Logical xor slice elements with corresponding elements of @a v.
156 void operator^=(const valarray<_Tp>&) const;
157 /// Logical and slice elements with corresponding elements of @a v.
158 void operator&=(const valarray<_Tp>&) const;
159 /// Logical or slice elements with corresponding elements of @a v.
160 void operator|=(const valarray<_Tp>&) const;
161 /// Left shift slice elements by corresponding elements of @a v.
162 void operator<<=(const valarray<_Tp>&) const;
163 /// Right shift slice elements by corresponding elements of @a v.
164 void operator>>=(const valarray<_Tp>&) const;
165 /// Assign all slice elements to @a t.
166 void operator=(const _Tp &) const;
167 // ~slice_array ();
168
169 template<class _Dom>
170 void operator=(const _Expr<_Dom, _Tp>&) const;
171 template<class _Dom>
172 void operator*=(const _Expr<_Dom, _Tp>&) const;
173 template<class _Dom>
174 void operator/=(const _Expr<_Dom, _Tp>&) const;
175 template<class _Dom>
176 void operator%=(const _Expr<_Dom, _Tp>&) const;
177 template<class _Dom>
178 void operator+=(const _Expr<_Dom, _Tp>&) const;
179 template<class _Dom>
180 void operator-=(const _Expr<_Dom, _Tp>&) const;
181 template<class _Dom>
182 void operator^=(const _Expr<_Dom, _Tp>&) const;
183 template<class _Dom>
184 void operator&=(const _Expr<_Dom, _Tp>&) const;
185 template<class _Dom>
186 void operator|=(const _Expr<_Dom, _Tp>&) const;
187 template<class _Dom>
188 void operator<<=(const _Expr<_Dom, _Tp>&) const;
189 template<class _Dom>
190 void operator>>=(const _Expr<_Dom, _Tp>&) const;
191
192 private:
193 friend class valarray<_Tp>;
194 slice_array(_Array<_Tp>, const slice&);
195
196 const size_t _M_sz;
197 const size_t _M_stride;
198 const _Array<_Tp> _M_array;
199
200 #if __cplusplus < 201103L
201 // not implemented
202 slice_array();
203 #else
204 public:
205 slice_array() = delete;
206 #endif
207 };
208
209 template<typename _Tp>
210 inline
211 slice_array<_Tp>::slice_array(_Array<_Tp> __a, const slice& __s)
212 : _M_sz(__s.size()), _M_stride(__s.stride()),
213 _M_array(__a.begin() + __s.start()) {}
214
215 template<typename _Tp>
216 inline
217 slice_array<_Tp>::slice_array(const slice_array<_Tp>& __a)
218 : _M_sz(__a._M_sz), _M_stride(__a._M_stride), _M_array(__a._M_array) {}
219
220 // template<typename _Tp>
221 // inline slice_array<_Tp>::~slice_array () {}
222
223 template<typename _Tp>
224 inline slice_array<_Tp>&
225 slice_array<_Tp>::operator=(const slice_array<_Tp>& __a)
226 {
227 std::__valarray_copy(__a._M_array, __a._M_sz, __a._M_stride,
228 _M_array, _M_stride);
229 return *this;
230 }
231
232 template<typename _Tp>
233 inline void
234 slice_array<_Tp>::operator=(const _Tp& __t) const
235 { std::__valarray_fill(_M_array, _M_sz, _M_stride, __t); }
236
237 template<typename _Tp>
238 inline void
239 slice_array<_Tp>::operator=(const valarray<_Tp>& __v) const
240 { std::__valarray_copy(_Array<_Tp>(__v), _M_array, _M_sz, _M_stride); }
241
242 template<typename _Tp>
243 template<class _Dom>
244 inline void
245 slice_array<_Tp>::operator=(const _Expr<_Dom,_Tp>& __e) const
246 { std::__valarray_copy(__e, _M_sz, _M_array, _M_stride); }
247
248 /// @cond undocumented
249 #undef _DEFINE_VALARRAY_OPERATOR
250 #define _DEFINE_VALARRAY_OPERATOR(_Op,_Name) \
251 template<typename _Tp> \
252 inline void \
253 slice_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const \
254 { \
255 _Array_augmented_##_Name(_M_array, _M_sz, _M_stride, _Array<_Tp>(__v));\
256 } \
257 \
258 template<typename _Tp> \
259 template<class _Dom> \
260 inline void \
261 slice_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
262 { \
263 _Array_augmented_##_Name(_M_array, _M_stride, __e, _M_sz); \
264 }
265
266
267 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
268 _DEFINE_VALARRAY_OPERATOR(/, __divides)
269 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
270 _DEFINE_VALARRAY_OPERATOR(+, __plus)
271 _DEFINE_VALARRAY_OPERATOR(-, __minus)
272 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
273 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
274 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
275 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
276 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
277
278 #undef _DEFINE_VALARRAY_OPERATOR
279 /// @endcond
280
281 /// @} group numeric_arrays
282
283 _GLIBCXX_END_NAMESPACE_VERSION
284 } // namespace
285
286 #endif /* _SLICE_ARRAY_H */