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The C and C++ Include Header Files
cat -n /usr/include/c++/15/bits/gslice.h
1 // The template and inlines for the -*- C++ -*- gslice class. 2 3 // Copyright (C) 1997-2025 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/gslice.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 _GSLICE_H 33 #define _GSLICE_H 1 34 35 #ifdef _GLIBCXX_SYSHDR 36 #pragma GCC system_header 37 #endif 38 39 namespace std _GLIBCXX_VISIBILITY(default) 40 { 41 _GLIBCXX_BEGIN_NAMESPACE_VERSION 42 43 /** 44 * @addtogroup numeric_arrays 45 * @{ 46 */ 47 48 /** 49 * @brief Class defining multi-dimensional subset of an array. 50 * 51 * The slice class represents a multi-dimensional subset of an array, 52 * specified by three parameter sets: start offset, size array, and stride 53 * array. The start offset is the index of the first element of the array 54 * that is part of the subset. The size and stride array describe each 55 * dimension of the slice. Size is the number of elements in that 56 * dimension, and stride is the distance in the array between successive 57 * elements in that dimension. Each dimension's size and stride is taken 58 * to begin at an array element described by the previous dimension. The 59 * size array and stride array must be the same size. 60 * 61 * For example, if you have offset==3, stride[0]==11, size[1]==3, 62 * stride[1]==3, then slice[0,0]==array[3], slice[0,1]==array[6], 63 * slice[0,2]==array[9], slice[1,0]==array[14], slice[1,1]==array[17], 64 * slice[1,2]==array[20]. 65 */ 66 class gslice 67 { 68 public: 69 /// Construct an empty slice. 70 gslice(); 71 72 /** 73 * @brief Construct a slice. 74 * 75 * Constructs a slice with as many dimensions as the length of the @a l 76 * and @a s arrays. 77 * 78 * @param __o Offset in array of first element. 79 * @param __l Array of dimension lengths. 80 * @param __s Array of dimension strides between array elements. 81 */ 82 gslice(size_t __o, const valarray<size_t>& __l, 83 const valarray<size_t>& __s); 84 85 // XXX: the IS says the copy-ctor and copy-assignment operators are 86 // synthesized by the compiler but they are just unsuitable 87 // for a ref-counted semantic 88 /// Copy constructor. 89 gslice(const gslice&); 90 91 /// Destructor. 92 ~gslice(); 93 94 // XXX: See the note above. 95 /// Assignment operator. 96 gslice& operator=(const gslice&); 97 98 /// Return array offset of first slice element. 99 size_t start() const; 100 101 /// Return array of sizes of slice dimensions. 102 valarray<size_t> size() const; 103 104 /// Return array of array strides for each dimension. 105 valarray<size_t> stride() const; 106 107 private: 108 struct _Indexer 109 { 110 size_t _M_count; 111 size_t _M_start; 112 valarray<size_t> _M_size; 113 valarray<size_t> _M_stride; 114 valarray<size_t> _M_index; // Linear array of referenced indices 115 116 _Indexer() 117 : _M_count(1), _M_start(0), _M_size(), _M_stride(), _M_index() {} 118 119 _Indexer(size_t, const valarray<size_t>&, 120 const valarray<size_t>&); 121 122 void 123 _M_increment_use() 124 { ++_M_count; } 125 126 size_t 127 _M_decrement_use() 128 { return --_M_count; } 129 }; 130 131 _Indexer* _M_index; 132 133 template<typename _Tp> friend class valarray; 134 }; 135 136 inline size_t 137 gslice::start() const 138 { return _M_index ? _M_index->_M_start : 0; } 139 140 inline valarray<size_t> 141 gslice::size() const 142 { return _M_index ? _M_index->_M_size : valarray<size_t>(); } 143 144 inline valarray<size_t> 145 gslice::stride() const 146 { return _M_index ? _M_index->_M_stride : valarray<size_t>(); } 147 148 // _GLIBCXX_RESOLVE_LIB_DEFECTS 149 // 543. valarray slice default constructor 150 inline 151 gslice::gslice() 152 : _M_index(new gslice::_Indexer()) {} 153 154 inline 155 gslice::gslice(size_t __o, const valarray<size_t>& __l, 156 const valarray<size_t>& __s) 157 : _M_index(new gslice::_Indexer(__o, __l, __s)) {} 158 159 inline 160 gslice::gslice(const gslice& __g) 161 : _M_index(__g._M_index) 162 { if (_M_index) _M_index->_M_increment_use(); } 163 164 inline 165 gslice::~gslice() 166 { 167 if (_M_index && _M_index->_M_decrement_use() == 0) 168 delete _M_index; 169 } 170 171 inline gslice& 172 gslice::operator=(const gslice& __g) 173 { 174 // Safe for self-assignment. Checking for it would add overhead just to 175 // optimize a case that should never happen anyway. 176 if (__g._M_index) 177 __g._M_index->_M_increment_use(); 178 if (_M_index && _M_index->_M_decrement_use() == 0) 179 delete _M_index; 180 _M_index = __g._M_index; 181 return *this; 182 } 183 184 /// @} group numeric_arrays 185 186 _GLIBCXX_END_NAMESPACE_VERSION 187 } // namespace 188 189 #endif /* _GSLICE_H */
