libstdc++
slice_array.h
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1 // The template and inlines for the -*- C++ -*- slice_array class.
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2009,
4 // 2010 Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
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23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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25 
26 /** @file bits/slice_array.h
27  * This is an internal header file, included by other library headers.
28  * Do not attempt to use it directly. @headername{valarray}
29  */
30 
31 // Written by Gabriel Dos Reis <[email protected]>
32 
33 #ifndef _SLICE_ARRAY_H
34 #define _SLICE_ARRAY_H 1
35 
36 #pragma GCC system_header
37 
38 namespace std _GLIBCXX_VISIBILITY(default)
39 {
40 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 
42  /**
43  * @addtogroup numeric_arrays
44  * @{
45  */
46 
47  /**
48  * @brief Class defining one-dimensional subset of an array.
49  *
50  * The slice class represents a one-dimensional subset of an array,
51  * specified by three parameters: start offset, size, and stride. The
52  * start offset is the index of the first element of the array that is part
53  * of the subset. The size is the total number of elements in the subset.
54  * Stride is the distance between each successive array element to include
55  * in the subset.
56  *
57  * For example, with an array of size 10, and a slice with offset 1, size 3
58  * and stride 2, the subset consists of array elements 1, 3, and 5.
59  */
60  class slice
61  {
62  public:
63  /// Construct an empty slice.
64  slice();
65 
66  /**
67  * @brief Construct a slice.
68  *
69  * @param o Offset in array of first element.
70  * @param d Number of elements in slice.
71  * @param s Stride between array elements.
72  */
73  slice(size_t, size_t, size_t);
74 
75  /// Return array offset of first slice element.
76  size_t start() const;
77  /// Return size of slice.
78  size_t size() const;
79  /// Return array stride of slice.
80  size_t stride() const;
81 
82  private:
83  size_t _M_off; // offset
84  size_t _M_sz; // size
85  size_t _M_st; // stride unit
86  };
87 
88  // _GLIBCXX_RESOLVE_LIB_DEFECTS
89  // 543. valarray slice default constructor
90  inline
91  slice::slice()
92  : _M_off(0), _M_sz(0), _M_st(0) {}
93 
94  inline
95  slice::slice(size_t __o, size_t __d, size_t __s)
96  : _M_off(__o), _M_sz(__d), _M_st(__s) {}
97 
98  inline size_t
99  slice::start() const
100  { return _M_off; }
101 
102  inline size_t
103  slice::size() const
104  { return _M_sz; }
105 
106  inline size_t
107  slice::stride() const
108  { return _M_st; }
109 
110  /**
111  * @brief Reference to one-dimensional subset of an array.
112  *
113  * A slice_array is a reference to the actual elements of an array
114  * specified by a slice. The way to get a slice_array is to call
115  * operator[](slice) on a valarray. The returned slice_array then permits
116  * carrying operations out on the referenced subset of elements in the
117  * original valarray. For example, operator+=(valarray) will add values
118  * to the subset of elements in the underlying valarray this slice_array
119  * refers to.
120  *
121  * @param Tp Element type.
122  */
123  template<typename _Tp>
124  class slice_array
125  {
126  public:
127  typedef _Tp value_type;
128 
129  // _GLIBCXX_RESOLVE_LIB_DEFECTS
130  // 253. valarray helper functions are almost entirely useless
131 
132  /// Copy constructor. Both slices refer to the same underlying array.
133  slice_array(const slice_array&);
134 
135  /// Assignment operator. Assigns slice elements to corresponding
136  /// elements of @a a.
137  slice_array& operator=(const slice_array&);
138 
139  /// Assign slice elements to corresponding elements of @a v.
140  void operator=(const valarray<_Tp>&) const;
141  /// Multiply slice elements by corresponding elements of @a v.
142  void operator*=(const valarray<_Tp>&) const;
143  /// Divide slice elements by corresponding elements of @a v.
144  void operator/=(const valarray<_Tp>&) const;
145  /// Modulo slice elements by corresponding elements of @a v.
146  void operator%=(const valarray<_Tp>&) const;
147  /// Add corresponding elements of @a v to slice elements.
148  void operator+=(const valarray<_Tp>&) const;
149  /// Subtract corresponding elements of @a v from slice elements.
150  void operator-=(const valarray<_Tp>&) const;
151  /// Logical xor slice elements with corresponding elements of @a v.
152  void operator^=(const valarray<_Tp>&) const;
153  /// Logical and slice elements with corresponding elements of @a v.
154  void operator&=(const valarray<_Tp>&) const;
155  /// Logical or slice elements with corresponding elements of @a v.
156  void operator|=(const valarray<_Tp>&) const;
157  /// Left shift slice elements by corresponding elements of @a v.
158  void operator<<=(const valarray<_Tp>&) const;
159  /// Right shift slice elements by corresponding elements of @a v.
160  void operator>>=(const valarray<_Tp>&) const;
161  /// Assign all slice elements to @a t.
162  void operator=(const _Tp &) const;
163  // ~slice_array ();
164 
165  template<class _Dom>
166  void operator=(const _Expr<_Dom, _Tp>&) const;
167  template<class _Dom>
168  void operator*=(const _Expr<_Dom, _Tp>&) const;
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 
188  private:
189  friend class valarray<_Tp>;
190  slice_array(_Array<_Tp>, const slice&);
191 
192  const size_t _M_sz;
193  const size_t _M_stride;
194  const _Array<_Tp> _M_array;
195 
196  // not implemented
197  slice_array();
198  };
199 
200  template<typename _Tp>
201  inline
202  slice_array<_Tp>::slice_array(_Array<_Tp> __a, const slice& __s)
203  : _M_sz(__s.size()), _M_stride(__s.stride()),
204  _M_array(__a.begin() + __s.start()) {}
205 
206  template<typename _Tp>
207  inline
208  slice_array<_Tp>::slice_array(const slice_array<_Tp>& a)
209  : _M_sz(a._M_sz), _M_stride(a._M_stride), _M_array(a._M_array) {}
210 
211  // template<typename _Tp>
212  // inline slice_array<_Tp>::~slice_array () {}
213 
214  template<typename _Tp>
215  inline slice_array<_Tp>&
216  slice_array<_Tp>::operator=(const slice_array<_Tp>& __a)
217  {
218  std::__valarray_copy(__a._M_array, __a._M_sz, __a._M_stride,
219  _M_array, _M_stride);
220  return *this;
221  }
222 
223  template<typename _Tp>
224  inline void
225  slice_array<_Tp>::operator=(const _Tp& __t) const
226  { std::__valarray_fill(_M_array, _M_sz, _M_stride, __t); }
227 
228  template<typename _Tp>
229  inline void
230  slice_array<_Tp>::operator=(const valarray<_Tp>& __v) const
231  { std::__valarray_copy(_Array<_Tp>(__v), _M_array, _M_sz, _M_stride); }
232 
233  template<typename _Tp>
234  template<class _Dom>
235  inline void
236  slice_array<_Tp>::operator=(const _Expr<_Dom,_Tp>& __e) const
237  { std::__valarray_copy(__e, _M_sz, _M_array, _M_stride); }
238 
239 #undef _DEFINE_VALARRAY_OPERATOR
240 #define _DEFINE_VALARRAY_OPERATOR(_Op,_Name) \
241  template<typename _Tp> \
242  inline void \
243  slice_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const \
244  { \
245  _Array_augmented_##_Name(_M_array, _M_sz, _M_stride, _Array<_Tp>(__v));\
246  } \
247  \
248  template<typename _Tp> \
249  template<class _Dom> \
250  inline void \
251  slice_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
252  { \
253  _Array_augmented_##_Name(_M_array, _M_stride, __e, _M_sz); \
254  }
255 
256 
257 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
258 _DEFINE_VALARRAY_OPERATOR(/, __divides)
259 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
260 _DEFINE_VALARRAY_OPERATOR(+, __plus)
261 _DEFINE_VALARRAY_OPERATOR(-, __minus)
262 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
263 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
264 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
265 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
266 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
267 
268 #undef _DEFINE_VALARRAY_OPERATOR
269 
270  // @} group numeric_arrays
271 
272 _GLIBCXX_END_NAMESPACE_VERSION
273 } // namespace
274 
275 #endif /* _SLICE_ARRAY_H */