1 | #ifndef _theplu_yat_utility_stride_iterator_ |
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2 | #define _theplu_yat_utility_stride_iterator_ |
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3 | |
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4 | // $Id: StrideIterator.h 1066 2008-02-10 22:48:19Z peter $ |
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5 | |
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6 | /* |
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7 | Copyright (C) 2008 Peter Johansson |
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8 | |
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9 | This file is part of the yat library, http://trac.thep.lu.se/yat |
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10 | |
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11 | The yat library is free software; you can redistribute it and/or |
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12 | modify it under the terms of the GNU General Public License as |
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13 | published by the Free Software Foundation; either version 2 of the |
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14 | License, or (at your option) any later version. |
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15 | |
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16 | The yat library is distributed in the hope that it will be useful, |
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17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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19 | General Public License for more details. |
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20 | |
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21 | You should have received a copy of the GNU General Public License |
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22 | along with this program; if not, write to the Free Software |
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23 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA |
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24 | 02111-1307, USA. |
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25 | */ |
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26 | |
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27 | #include "iterator_traits.h" |
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28 | #include "yat_assert.h" |
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29 | |
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30 | #include <iterator> |
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31 | |
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32 | namespace theplu { |
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33 | namespace yat { |
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34 | namespace utility { |
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35 | |
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36 | // forward declaration |
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37 | template<typename Iter> |
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38 | class StrideIterator; |
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39 | |
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40 | /** |
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41 | StrideIterator is weighted if underlying iterator is weighted. |
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42 | */ |
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43 | template <typename Iter> |
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44 | struct weighted_iterator_traits<StrideIterator<Iter> > { |
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45 | typedef typename weighted_iterator_traits<Iter>::type type; |
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46 | }; |
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47 | |
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48 | /** |
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49 | @brief Adaptor using a stride on underlying iterator |
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50 | |
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51 | Works as underlying iterator except that all arithmetic uses the |
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52 | stride, so e.g., ++StrideIterator returns underlying |
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53 | _iterator+stride |
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54 | |
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55 | */ |
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56 | template<typename Iter> |
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57 | class StrideIterator |
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58 | : public std::iterator<typename std::iterator_traits<Iter>::iterator_category, |
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59 | typename std::iterator_traits<Iter>::value_type, |
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60 | typename std::iterator_traits<Iter>::difference_type, |
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61 | typename std::iterator_traits<Iter>::pointer, |
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62 | typename std::iterator_traits<Iter>::reference> |
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63 | { |
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64 | public: |
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65 | typedef Iter iterator_type; |
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66 | typedef typename std::iterator_traits<Iter>::value_type value_type; |
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67 | typedef typename std::iterator_traits<Iter>::difference_type difference_type; |
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68 | typedef typename std::iterator_traits<Iter>::reference reference; |
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69 | typedef typename std::iterator_traits<Iter>::pointer pointer; |
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70 | typedef typename yat::utility::weighted_iterator_traits<Iter>::type w_type; |
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71 | |
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72 | /** |
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73 | \brief Constructor |
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74 | */ |
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75 | explicit StrideIterator(Iter p, difference_type stride=1) |
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76 | : iterator_(p), stride_(stride) {} |
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77 | |
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78 | |
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79 | /** |
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80 | */ |
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81 | // Peter, this is ugly hack to provide iteartor to const_iterator |
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82 | // for our gsl_iterators - solution? use Boost:iterator_adaptor |
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83 | operator StrideIterator<const value_type*>() |
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84 | { return StrideIterator<const value_type*>(base(), stride_); } |
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85 | |
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86 | /** |
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87 | \return underlying iterator |
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88 | */ |
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89 | inline Iter base(void) const { return iterator_; } |
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90 | |
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91 | /** |
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92 | \return stride |
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93 | */ |
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94 | inline size_t stride(void) const { return stride_; } |
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95 | |
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96 | /** |
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97 | \return element |
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98 | */ |
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99 | reference operator*(void) const |
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100 | { return *iterator_; } |
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101 | |
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102 | /** |
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103 | */ |
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104 | pointer operator->() const { return &(operator*()); } |
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105 | |
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106 | /** |
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107 | \return element \a n steps forward |
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108 | */ |
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109 | reference operator[](difference_type n) const |
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110 | { |
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111 | return iterator_[stride_*n]; |
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112 | } |
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113 | |
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114 | /** |
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115 | \brief pre-increment |
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116 | |
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117 | \return reference to *this |
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118 | */ |
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119 | StrideIterator& operator++(void) { iterator_+=stride_; return *this; } |
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120 | |
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121 | /** |
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122 | \brief post-increment |
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123 | |
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124 | \return copy of iterator prior increment |
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125 | */ |
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126 | StrideIterator operator++(int) |
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127 | { StrideIterator tmp(*this); iterator_+=stride_; return tmp;} |
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128 | |
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129 | /** |
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130 | \brief iterate \f$ n \f$ steps forward |
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131 | |
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132 | \return reference to resulting iterator |
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133 | */ |
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134 | StrideIterator& operator+=(int n) { iterator_+=stride_*n; return *this; } |
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135 | |
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136 | /** |
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137 | \brief post-decrement |
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138 | |
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139 | \return copy of iterator prior decrement |
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140 | */ |
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141 | StrideIterator operator--(int) |
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142 | { StrideIterator tmp(*this); iterator_-=stride_; return tmp;} |
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143 | |
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144 | /** |
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145 | \brief pre-decrement |
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146 | |
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147 | \return reference to resulting iterator |
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148 | */ |
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149 | StrideIterator& operator--(void) { iterator_-=stride_; return *this; } |
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150 | |
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151 | /** |
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152 | \brief iterate \f$ n \f$ steps backwards |
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153 | |
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154 | \return reference to resulting iterator |
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155 | */ |
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156 | StrideIterator& operator-=(int n) { iterator_-=n*stride_; return *this; } |
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157 | |
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158 | /** |
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159 | \brief addition operator |
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160 | |
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161 | \return copy of resulting iterator |
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162 | */ |
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163 | friend StrideIterator operator+(const StrideIterator& lhs,difference_type n) |
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164 | { StrideIterator tmp(lhs); tmp+=n; return tmp; } |
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165 | |
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166 | /** |
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167 | \brief subtraction operator |
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168 | |
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169 | \return copy of resulting iterator |
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170 | */ |
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171 | friend StrideIterator operator-(const StrideIterator& lhs, |
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172 | difference_type n) |
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173 | { StrideIterator tmp(lhs); tmp-=n; return tmp; } |
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174 | |
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175 | /** |
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176 | \brief difference operator |
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177 | |
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178 | \return distance between \a lhs and \a rhs |
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179 | */ |
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180 | friend difference_type operator-(const StrideIterator& lhs, |
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181 | const StrideIterator& rhs) |
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182 | { |
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183 | yat_assert<std::runtime_error>(lhs.stride_==rhs.stride_, |
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184 | "StrideIterator::operator- different stride in lhs and rhs."); |
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185 | return static_cast<difference_type>( (lhs.iterator_-rhs.iterator_)/ |
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186 | lhs.stride_); |
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187 | } |
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188 | |
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189 | |
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190 | /** |
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191 | \brief Equality operator |
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192 | |
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193 | \return True if \a lhs and \a rhs are pointing to same element |
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194 | */ |
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195 | friend bool operator==(const StrideIterator& lhs, const StrideIterator& rhs) |
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196 | { return lhs.iterator_==rhs.iterator_; } |
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197 | |
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198 | /** |
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199 | \brief Non-equality operator |
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200 | |
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201 | \return False if \a lhs and \a rhs are pointing to same element |
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202 | */ |
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203 | friend bool operator!=(const StrideIterator& lhs, const StrideIterator& rhs) |
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204 | { return lhs.iterator_!=rhs.iterator_; } |
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205 | |
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206 | /** |
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207 | \brief Less operator |
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208 | */ |
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209 | friend bool operator<(const StrideIterator& lhs, const StrideIterator& rhs) |
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210 | { return lhs.iterator_<rhs.iterator_; } |
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211 | |
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212 | /** |
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213 | \brief Less equal operator |
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214 | */ |
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215 | friend bool operator<=(const StrideIterator& lhs, const StrideIterator& rhs) |
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216 | { return lhs.iterator_<=rhs.iterator_; } |
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217 | |
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218 | /** |
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219 | \brief Larger operator |
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220 | */ |
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221 | friend bool operator>(const StrideIterator& lhs, const StrideIterator& rhs) |
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222 | { return lhs.iterator_>rhs.iterator_; } |
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223 | |
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224 | /** |
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225 | \brief Larger equal operator |
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226 | */ |
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227 | friend bool operator>=(const StrideIterator& lhs, const StrideIterator& rhs) |
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228 | { return lhs.iterator_>=rhs.iterator_; } |
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229 | |
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230 | private: |
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231 | Iter iterator_; |
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232 | size_t stride_; |
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233 | |
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234 | // Using compiler generated copy |
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235 | //StrideIterator(const StrideIterator&); |
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236 | //StrideIterator& operator=(const StrideIterator&); |
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237 | }; |
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238 | |
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239 | |
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240 | |
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241 | |
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242 | |
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243 | }}} // of namespace utility, yat, and theplu |
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244 | |
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245 | #endif |
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