libstdc++
slice_array.h
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1 // The template and inlines for the -*- C++ -*- slice_array class.
2 
3 // Copyright (C) 1997-2017 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
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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 <[email protected]>
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  private:
82  size_t _M_off; // offset
83  size_t _M_sz; // size
84  size_t _M_st; // stride unit
85  };
86 
87  // _GLIBCXX_RESOLVE_LIB_DEFECTS
88  // 543. valarray slice default constructor
89  inline
91  : _M_off(0), _M_sz(0), _M_st(0) {}
92 
93  inline
94  slice::slice(size_t __o, size_t __d, size_t __s)
95  : _M_off(__o), _M_sz(__d), _M_st(__s) {}
96 
97  inline size_t
98  slice::start() const
99  { return _M_off; }
100 
101  inline size_t
102  slice::size() const
103  { return _M_sz; }
104 
105  inline size_t
107  { return _M_st; }
108 
109  /**
110  * @brief Reference to one-dimensional subset of an array.
111  *
112  * A slice_array is a reference to the actual elements of an array
113  * specified by a slice. The way to get a slice_array is to call
114  * operator[](slice) on a valarray. The returned slice_array then permits
115  * carrying operations out on the referenced subset of elements in the
116  * original valarray. For example, operator+=(valarray) will add values
117  * to the subset of elements in the underlying valarray this slice_array
118  * refers to.
119  *
120  * @param Tp Element type.
121  */
122  template<typename _Tp>
123  class slice_array
124  {
125  public:
126  typedef _Tp value_type;
127 
128  // _GLIBCXX_RESOLVE_LIB_DEFECTS
129  // 253. valarray helper functions are almost entirely useless
130 
131  /// Copy constructor. Both slices refer to the same underlying array.
132  slice_array(const slice_array&);
133 
134  /// Assignment operator. Assigns slice elements to corresponding
135  /// elements of @a a.
136  slice_array& operator=(const slice_array&);
137 
138  /// Assign slice elements to corresponding elements of @a v.
139  void operator=(const valarray<_Tp>&) const;
140  /// Multiply slice elements by corresponding elements of @a v.
141  void operator*=(const valarray<_Tp>&) const;
142  /// Divide slice elements by corresponding elements of @a v.
143  void operator/=(const valarray<_Tp>&) const;
144  /// Modulo slice elements by corresponding elements of @a v.
145  void operator%=(const valarray<_Tp>&) const;
146  /// Add corresponding elements of @a v to slice elements.
147  void operator+=(const valarray<_Tp>&) const;
148  /// Subtract corresponding elements of @a v from slice elements.
149  void operator-=(const valarray<_Tp>&) const;
150  /// Logical xor slice elements with corresponding elements of @a v.
151  void operator^=(const valarray<_Tp>&) const;
152  /// Logical and slice elements with corresponding elements of @a v.
153  void operator&=(const valarray<_Tp>&) const;
154  /// Logical or slice elements with corresponding elements of @a v.
155  void operator|=(const valarray<_Tp>&) const;
156  /// Left shift slice elements by corresponding elements of @a v.
157  void operator<<=(const valarray<_Tp>&) const;
158  /// Right shift slice elements by corresponding elements of @a v.
159  void operator>>=(const valarray<_Tp>&) const;
160  /// Assign all slice elements to @a t.
161  void operator=(const _Tp &) const;
162  // ~slice_array ();
163 
164  template<class _Dom>
165  void operator=(const _Expr<_Dom, _Tp>&) const;
166  template<class _Dom>
167  void operator*=(const _Expr<_Dom, _Tp>&) const;
168  template<class _Dom>
169  void operator/=(const _Expr<_Dom, _Tp>&) const;
170  template<class _Dom>
171  void operator%=(const _Expr<_Dom, _Tp>&) const;
172  template<class _Dom>
173  void operator+=(const _Expr<_Dom, _Tp>&) const;
174  template<class _Dom>
175  void operator-=(const _Expr<_Dom, _Tp>&) const;
176  template<class _Dom>
177  void operator^=(const _Expr<_Dom, _Tp>&) const;
178  template<class _Dom>
179  void operator&=(const _Expr<_Dom, _Tp>&) const;
180  template<class _Dom>
181  void operator|=(const _Expr<_Dom, _Tp>&) const;
182  template<class _Dom>
183  void operator<<=(const _Expr<_Dom, _Tp>&) const;
184  template<class _Dom>
185  void operator>>=(const _Expr<_Dom, _Tp>&) const;
186 
187  private:
188  friend class valarray<_Tp>;
189  slice_array(_Array<_Tp>, const slice&);
190 
191  const size_t _M_sz;
192  const size_t _M_stride;
193  const _Array<_Tp> _M_array;
194 
195  // not implemented
196  slice_array();
197  };
198 
199  template<typename _Tp>
200  inline
201  slice_array<_Tp>::slice_array(_Array<_Tp> __a, const slice& __s)
202  : _M_sz(__s.size()), _M_stride(__s.stride()),
203  _M_array(__a.begin() + __s.start()) {}
204 
205  template<typename _Tp>
206  inline
208  : _M_sz(__a._M_sz), _M_stride(__a._M_stride), _M_array(__a._M_array) {}
209 
210  // template<typename _Tp>
211  // inline slice_array<_Tp>::~slice_array () {}
212 
213  template<typename _Tp>
214  inline slice_array<_Tp>&
216  {
217  std::__valarray_copy(__a._M_array, __a._M_sz, __a._M_stride,
218  _M_array, _M_stride);
219  return *this;
220  }
221 
222  template<typename _Tp>
223  inline void
224  slice_array<_Tp>::operator=(const _Tp& __t) const
225  { std::__valarray_fill(_M_array, _M_sz, _M_stride, __t); }
226 
227  template<typename _Tp>
228  inline void
230  { std::__valarray_copy(_Array<_Tp>(__v), _M_array, _M_sz, _M_stride); }
231 
232  template<typename _Tp>
233  template<class _Dom>
234  inline void
235  slice_array<_Tp>::operator=(const _Expr<_Dom,_Tp>& __e) const
236  { std::__valarray_copy(__e, _M_sz, _M_array, _M_stride); }
237 
238 #undef _DEFINE_VALARRAY_OPERATOR
239 #define _DEFINE_VALARRAY_OPERATOR(_Op,_Name) \
240  template<typename _Tp> \
241  inline void \
242  slice_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const \
243  { \
244  _Array_augmented_##_Name(_M_array, _M_sz, _M_stride, _Array<_Tp>(__v));\
245  } \
246  \
247  template<typename _Tp> \
248  template<class _Dom> \
249  inline void \
250  slice_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
251  { \
252  _Array_augmented_##_Name(_M_array, _M_stride, __e, _M_sz); \
253  }
254 
255 
256 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
257 _DEFINE_VALARRAY_OPERATOR(/, __divides)
258 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
259 _DEFINE_VALARRAY_OPERATOR(+, __plus)
260 _DEFINE_VALARRAY_OPERATOR(-, __minus)
261 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
262 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
263 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
264 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
265 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
266 
267 #undef _DEFINE_VALARRAY_OPERATOR
268 
269  // @} group numeric_arrays
270 
271 _GLIBCXX_END_NAMESPACE_VERSION
272 } // namespace
273 
274 #endif /* _SLICE_ARRAY_H */
Class defining one-dimensional subset of an array.
Definition: slice_array.h:59
ISO C++ entities toplevel namespace is std.
size_t stride() const
Return array stride of slice.
Definition: slice_array.h:106
slice()
Construct an empty slice.
Definition: slice_array.h:90
Smart array designed to support numeric processing.
Definition: valarray:78
slice_array & operator=(const slice_array &)
Assignment operator. Assigns slice elements to corresponding elements of a.
Definition: slice_array.h:215
size_t start() const
Return array offset of first slice element.
Definition: slice_array.h:98
Reference to one-dimensional subset of an array.
Definition: valarray:80
size_t size() const
Return size of slice.
Definition: slice_array.h:102