1// The template and inlines for the -*- C++ -*- gslice class. 2 3// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2004, 2005 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 2, 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// You should have received a copy of the GNU General Public License along 18// with this library; see the file COPYING. If not, write to the Free 19// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 20// USA. 21 22// As a special exception, you may use this file as part of a free software 23// library without restriction. Specifically, if other files instantiate 24// templates or use macros or inline functions from this file, or you compile 25// this file and link it with other files to produce an executable, this 26// file does not by itself cause the resulting executable to be covered by 27// the GNU General Public License. This exception does not however 28// invalidate any other reasons why the executable file might be covered by 29// the GNU General Public License. 30 31/** @file gslice.h 32 * This is an internal header file, included by other library headers. 33 * You should not attempt to use it directly. 34 */ 35 36// Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr> 37 38#ifndef _GSLICE_H 39#define _GSLICE_H 1 40 41#pragma GCC system_header 42 43_GLIBCXX_BEGIN_NAMESPACE(std) 44 45 /** 46 * @brief Class defining multi-dimensional subset of an array. 47 * 48 * The slice class represents a multi-dimensional subset of an array, 49 * specified by three parameter sets: start offset, size array, and stride 50 * array. The start offset is the index of the first element of the array 51 * that is part of the subset. The size and stride array describe each 52 * dimension of the slice. Size is the number of elements in that 53 * dimension, and stride is the distance in the array between successive 54 * elements in that dimension. Each dimension's size and stride is taken 55 * to begin at an array element described by the previous dimension. The 56 * size array and stride array must be the same size. 57 * 58 * For example, if you have offset==3, stride[0]==11, size[1]==3, 59 * stride[1]==3, then slice[0,0]==array[3], slice[0,1]==array[6], 60 * slice[0,2]==array[9], slice[1,0]==array[14], slice[1,1]==array[17], 61 * slice[1,2]==array[20]. 62 */ 63 class gslice 64 { 65 public: 66 /// Construct an empty slice. 67 gslice (); 68 69 /** 70 * @brief Construct a slice. 71 * 72 * Constructs a slice with as many dimensions as the length of the @a l 73 * and @a s arrays. 74 * 75 * @param o Offset in array of first element. 76 * @param l Array of dimension lengths. 77 * @param s Array of dimension strides between array elements. 78 */ 79 gslice(size_t, const valarray<size_t>&, const valarray<size_t>&); 80 81 // XXX: the IS says the copy-ctor and copy-assignment operators are 82 // synthetized by the compiler but they are just unsuitable 83 // for a ref-counted semantic 84 /// Copy constructor. 85 gslice(const gslice&); 86 87 /// Destructor. 88 ~gslice(); 89 90 // XXX: See the note above. 91 /// Assignment operator. 92 gslice& operator=(const gslice&); 93 94 /// Return array offset of first slice element. 95 size_t start() const; 96 97 /// Return array of sizes of slice dimensions. 98 valarray<size_t> size() const; 99 100 /// Return array of array strides for each dimension. 101 valarray<size_t> stride() const; 102 103 private: 104 struct _Indexer 105 { 106 size_t _M_count; 107 size_t _M_start; 108 valarray<size_t> _M_size; 109 valarray<size_t> _M_stride; 110 valarray<size_t> _M_index; // Linear array of referenced indices 111 _Indexer(size_t, const valarray<size_t>&, 112 const valarray<size_t>&); 113 void 114 _M_increment_use() 115 { ++_M_count; } 116 117 size_t 118 _M_decrement_use() 119 { return --_M_count; } 120 }; 121 122 _Indexer* _M_index; 123 124 template<typename _Tp> friend class valarray; 125 }; 126 127 inline size_t 128 gslice::start () const 129 { return _M_index ? _M_index->_M_start : 0; } 130 131 inline valarray<size_t> 132 gslice::size () const 133 { return _M_index ? _M_index->_M_size : valarray<size_t>(); } 134 135 inline valarray<size_t> 136 gslice::stride () const 137 { return _M_index ? _M_index->_M_stride : valarray<size_t>(); } 138 139 inline gslice::gslice () : _M_index(0) {} 140 141 inline 142 gslice::gslice(size_t __o, const valarray<size_t>& __l, 143 const valarray<size_t>& __s) 144 : _M_index(new gslice::_Indexer(__o, __l, __s)) {} 145 146 inline 147 gslice::gslice(const gslice& __g) : _M_index(__g._M_index) 148 { if (_M_index) _M_index->_M_increment_use(); } 149 150 inline 151 gslice::~gslice() 152 { 153 if (_M_index && _M_index->_M_decrement_use() == 0) 154 delete _M_index; 155 } 156 157 inline gslice& 158 gslice::operator= (const gslice& __g) 159 { 160 if (__g._M_index) 161 __g._M_index->_M_increment_use(); 162 if (_M_index && _M_index->_M_decrement_use() == 0) 163 delete _M_index; 164 _M_index = __g._M_index; 165 return *this; 166 } 167 168_GLIBCXX_END_NAMESPACE 169 170#endif /* _GSLICE_H */ 171