libstdc++
mask_array.h
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1 // The template and inlines for the -*- C++ -*- mask_array class.
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2009
4 // 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 
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25 
26 /** @file mask_array.h
27  * This is an internal header file, included by other library headers.
28  * You should not attempt to use it directly.
29  */
30 
31 // Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
32 
33 #ifndef _MASK_ARRAY_H
34 #define _MASK_ARRAY_H 1
35 
36 #pragma GCC system_header
37 
38 _GLIBCXX_BEGIN_NAMESPACE(std)
39 
40  /**
41  * @addtogroup numeric_arrays
42  * @{
43  */
44 
45  /**
46  * @brief Reference to selected subset of an array.
47  *
48  * A mask_array is a reference to the actual elements of an array specified
49  * by a bitmask in the form of an array of bool. The way to get a
50  * mask_array is to call operator[](valarray<bool>) on a valarray. The
51  * returned mask_array then permits carrying operations out on the
52  * referenced subset of elements in the original valarray.
53  *
54  * For example, if a mask_array is obtained using the array (false, true,
55  * false, true) as an argument, the mask array has two elements referring
56  * to array[1] and array[3] in the underlying array.
57  *
58  * @param Tp Element type.
59  */
60  template <class _Tp>
61  class mask_array
62  {
63  public:
64  typedef _Tp value_type;
65 
66  // _GLIBCXX_RESOLVE_LIB_DEFECTS
67  // 253. valarray helper functions are almost entirely useless
68 
69  /// Copy constructor. Both slices refer to the same underlying array.
70  mask_array (const mask_array&);
71 
72  /// Assignment operator. Assigns elements to corresponding elements
73  /// of @a a.
74  mask_array& operator=(const mask_array&);
75 
76  void operator=(const valarray<_Tp>&) const;
77  /// Multiply slice elements by corresponding elements of @a v.
78  void operator*=(const valarray<_Tp>&) const;
79  /// Divide slice elements by corresponding elements of @a v.
80  void operator/=(const valarray<_Tp>&) const;
81  /// Modulo slice elements by corresponding elements of @a v.
82  void operator%=(const valarray<_Tp>&) const;
83  /// Add corresponding elements of @a v to slice elements.
84  void operator+=(const valarray<_Tp>&) const;
85  /// Subtract corresponding elements of @a v from slice elements.
86  void operator-=(const valarray<_Tp>&) const;
87  /// Logical xor slice elements with corresponding elements of @a v.
88  void operator^=(const valarray<_Tp>&) const;
89  /// Logical and slice elements with corresponding elements of @a v.
90  void operator&=(const valarray<_Tp>&) const;
91  /// Logical or slice elements with corresponding elements of @a v.
92  void operator|=(const valarray<_Tp>&) const;
93  /// Left shift slice elements by corresponding elements of @a v.
94  void operator<<=(const valarray<_Tp>&) const;
95  /// Right shift slice elements by corresponding elements of @a v.
96  void operator>>=(const valarray<_Tp>&) const;
97  /// Assign all slice elements to @a t.
98  void operator=(const _Tp&) const;
99 
100  // ~mask_array ();
101 
102  template<class _Dom>
103  void operator=(const _Expr<_Dom,_Tp>&) const;
104  template<class _Dom>
105  void operator*=(const _Expr<_Dom,_Tp>&) const;
106  template<class _Dom>
107  void operator/=(const _Expr<_Dom,_Tp>&) const;
108  template<class _Dom>
109  void operator%=(const _Expr<_Dom,_Tp>&) const;
110  template<class _Dom>
111  void operator+=(const _Expr<_Dom,_Tp>&) const;
112  template<class _Dom>
113  void operator-=(const _Expr<_Dom,_Tp>&) const;
114  template<class _Dom>
115  void operator^=(const _Expr<_Dom,_Tp>&) const;
116  template<class _Dom>
117  void operator&=(const _Expr<_Dom,_Tp>&) const;
118  template<class _Dom>
119  void operator|=(const _Expr<_Dom,_Tp>&) const;
120  template<class _Dom>
121  void operator<<=(const _Expr<_Dom,_Tp>&) const;
122  template<class _Dom>
123  void operator>>=(const _Expr<_Dom,_Tp>&) const;
124 
125  private:
126  mask_array(_Array<_Tp>, size_t, _Array<bool>);
127  friend class valarray<_Tp>;
128 
129  const size_t _M_sz;
130  const _Array<bool> _M_mask;
131  const _Array<_Tp> _M_array;
132 
133  // not implemented
134  mask_array();
135  };
136 
137  template<typename _Tp>
139  : _M_sz(a._M_sz), _M_mask(a._M_mask), _M_array(a._M_array) {}
140 
141  template<typename _Tp>
142  inline
143  mask_array<_Tp>::mask_array(_Array<_Tp> __a, size_t __s, _Array<bool> __m)
144  : _M_sz(__s), _M_mask(__m), _M_array(__a) {}
145 
146  template<typename _Tp>
147  inline mask_array<_Tp>&
149  {
150  std::__valarray_copy(__a._M_array, __a._M_mask,
151  _M_sz, _M_array, _M_mask);
152  return *this;
153  }
154 
155  template<typename _Tp>
156  inline void
157  mask_array<_Tp>::operator=(const _Tp& __t) const
158  { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }
159 
160  template<typename _Tp>
161  inline void
162  mask_array<_Tp>::operator=(const valarray<_Tp>& __v) const
163  { std::__valarray_copy(_Array<_Tp>(__v), __v.size(), _M_array, _M_mask); }
164 
165  template<typename _Tp>
166  template<class _Ex>
167  inline void
168  mask_array<_Tp>::operator=(const _Expr<_Ex, _Tp>& __e) const
169  { std::__valarray_copy(__e, __e.size(), _M_array, _M_mask); }
170 
171 #undef _DEFINE_VALARRAY_OPERATOR
172 #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name) \
173  template<typename _Tp> \
174  inline void \
175  mask_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const \
176  { \
177  _Array_augmented_##_Name(_M_array, _M_mask, \
178  _Array<_Tp>(__v), __v.size()); \
179  } \
180  \
181  template<typename _Tp> \
182  template<class _Dom> \
183  inline void \
184  mask_array<_Tp>::operator _Op##=(const _Expr<_Dom, _Tp>& __e) const\
185  { \
186  _Array_augmented_##_Name(_M_array, _M_mask, __e, __e.size()); \
187  }
188 
189 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
190 _DEFINE_VALARRAY_OPERATOR(/, __divides)
191 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
192 _DEFINE_VALARRAY_OPERATOR(+, __plus)
193 _DEFINE_VALARRAY_OPERATOR(-, __minus)
194 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
195 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
196 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
197 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
198 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
199 
200 #undef _DEFINE_VALARRAY_OPERATOR
201 
202  // @} group numeric_arrays
203 
204 _GLIBCXX_END_NAMESPACE
205 
206 #endif /* _MASK_ARRAY_H */