1 | #ifndef DATE_TIME_PERIOD_HPP___ |
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2 | #define DATE_TIME_PERIOD_HPP___ |
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3 | |
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4 | /* Copyright (c) 2002,2003 CrystalClear Software, Inc. |
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5 | * Use, modification and distribution is subject to the |
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6 | * Boost Software License, Version 1.0. (See accompanying |
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7 | * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
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8 | * Author: Jeff Garland, Bart Garst |
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9 | * $Date: 2008-02-27 15:00:24 -0500 (Wed, 27 Feb 2008) $ |
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10 | */ |
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11 | |
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12 | /*! \file period.hpp |
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13 | This file contain the implementation of the period abstraction. This is |
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14 | basically the same idea as a range. Although this class is intended for |
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15 | use in the time library, it is pretty close to general enough for other |
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16 | numeric uses. |
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17 | |
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18 | */ |
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19 | |
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20 | #include "boost/operators.hpp" |
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21 | |
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22 | |
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23 | namespace boost { |
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24 | namespace date_time { |
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25 | //!Provides generalized period type useful in date-time systems |
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26 | /*!This template uses a class to represent a time point within the period |
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27 | and another class to represent a duration. As a result, this class is |
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28 | not appropriate for use when the number and duration representation |
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29 | are the same (eg: in the regular number domain). |
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30 | |
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31 | A period can be specified by providing either the begining point and |
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32 | a duration or the begining point and the end point( end is NOT part |
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33 | of the period but 1 unit past it. A period will be "invalid" if either |
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34 | end_point <= begin_point or the given duration is <= 0. Any valid period |
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35 | will return false for is_null(). |
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36 | |
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37 | Zero length periods are also considered invalid. Zero length periods are |
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38 | periods where the begining and end points are the same, or, the given |
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39 | duration is zero. For a zero length period, the last point will be one |
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40 | unit less than the begining point. |
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41 | |
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42 | In the case that the begin and last are the same, the period has a |
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43 | length of one unit. |
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44 | |
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45 | The best way to handle periods is usually to provide a begining point and |
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46 | a duration. So, day1 + 7 days is a week period which includes all of the |
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47 | first day and 6 more days (eg: Sun to Sat). |
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48 | |
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49 | */ |
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50 | template<class point_rep, class duration_rep> |
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51 | class period : private |
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52 | boost::less_than_comparable<period<point_rep, duration_rep> |
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53 | , boost::equality_comparable< period<point_rep, duration_rep> |
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54 | > > |
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55 | { |
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56 | public: |
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57 | typedef point_rep point_type; |
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58 | typedef duration_rep duration_type; |
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59 | |
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60 | period(point_rep first_point, point_rep end_point); |
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61 | period(point_rep first_point, duration_rep len); |
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62 | point_rep begin() const; |
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63 | point_rep end() const; |
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64 | point_rep last() const; |
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65 | duration_rep length() const; |
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66 | bool is_null() const; |
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67 | bool operator==(const period& rhs) const; |
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68 | bool operator<(const period& rhs) const; |
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69 | void shift(const duration_rep& d); |
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70 | void expand(const duration_rep& d); |
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71 | bool contains(const point_rep& point) const; |
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72 | bool contains(const period& other) const; |
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73 | bool intersects(const period& other) const; |
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74 | bool is_adjacent(const period& other) const; |
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75 | bool is_before(const point_rep& point) const; |
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76 | bool is_after(const point_rep& point) const; |
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77 | period intersection(const period& other) const; |
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78 | period merge(const period& other) const; |
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79 | period span(const period& other) const; |
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80 | private: |
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81 | point_rep begin_; |
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82 | point_rep last_; |
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83 | }; |
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84 | |
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85 | //! create a period from begin to last eg: [begin,end) |
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86 | /*! If end <= begin then the period will be invalid |
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87 | */ |
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88 | template<class point_rep, class duration_rep> |
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89 | inline |
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90 | period<point_rep,duration_rep>::period(point_rep first_point, |
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91 | point_rep end_point) : |
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92 | begin_(first_point), |
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93 | last_(end_point - duration_rep::unit()) |
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94 | {} |
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95 | |
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96 | //! create a period as [begin, begin+len) |
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97 | /*! If len is <= 0 then the period will be invalid |
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98 | */ |
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99 | template<class point_rep, class duration_rep> |
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100 | inline |
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101 | period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) : |
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102 | begin_(first_point), |
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103 | last_(first_point + len-duration_rep::unit()) |
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104 | { } |
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105 | |
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106 | |
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107 | //! Return the first element in the period |
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108 | template<class point_rep, class duration_rep> |
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109 | inline |
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110 | point_rep period<point_rep,duration_rep>::begin() const |
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111 | { |
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112 | return begin_; |
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113 | } |
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114 | |
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115 | //! Return one past the last element |
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116 | template<class point_rep, class duration_rep> |
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117 | inline |
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118 | point_rep period<point_rep,duration_rep>::end() const |
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119 | { |
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120 | return last_ + duration_rep::unit(); |
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121 | } |
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122 | |
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123 | //! Return the last item in the period |
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124 | template<class point_rep, class duration_rep> |
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125 | inline |
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126 | point_rep period<point_rep,duration_rep>::last() const |
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127 | { |
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128 | return last_; |
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129 | } |
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130 | |
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131 | //! True if period is ill formed (length is zero or less) |
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132 | template<class point_rep, class duration_rep> |
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133 | inline |
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134 | bool period<point_rep,duration_rep>::is_null() const |
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135 | { |
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136 | return end() <= begin_; |
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137 | } |
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138 | |
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139 | //! Return the length of the period |
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140 | template<class point_rep, class duration_rep> |
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141 | inline |
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142 | duration_rep period<point_rep,duration_rep>::length() const |
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143 | { |
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144 | if(last_ < begin_){ // invalid period |
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145 | return last_+duration_rep::unit() - begin_; |
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146 | } |
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147 | else{ |
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148 | return end() - begin_; // normal case |
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149 | } |
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150 | } |
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151 | |
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152 | //! Equality operator |
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153 | template<class point_rep, class duration_rep> |
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154 | inline |
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155 | bool period<point_rep,duration_rep>::operator==(const period& rhs) const |
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156 | { |
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157 | return ((begin_ == rhs.begin_) && |
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158 | (last_ == rhs.last_)); |
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159 | } |
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160 | |
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161 | //! Strict as defined by rhs.last <= lhs.last |
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162 | template<class point_rep, class duration_rep> |
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163 | inline |
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164 | bool period<point_rep,duration_rep>::operator<(const period& rhs) const |
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165 | { |
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166 | return (last_ < rhs.begin_); |
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167 | } |
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168 | |
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169 | |
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170 | //! Shift the start and end by the specified amount |
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171 | template<class point_rep, class duration_rep> |
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172 | inline |
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173 | void period<point_rep,duration_rep>::shift(const duration_rep& d) |
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174 | { |
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175 | begin_ = begin_ + d; |
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176 | last_ = last_ + d; |
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177 | } |
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178 | |
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179 | /** Expands the size of the period by the duration on both ends. |
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180 | * |
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181 | *So before expand |
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182 | *@code |
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183 | * |
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184 | * [-------] |
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185 | * ^ ^ ^ ^ ^ ^ ^ |
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186 | * 1 2 3 4 5 6 7 |
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187 | * |
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188 | *@endcode |
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189 | * After expand(2) |
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190 | *@code |
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191 | * |
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192 | * [----------------------] |
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193 | * ^ ^ ^ ^ ^ ^ ^ |
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194 | * 1 2 3 4 5 6 7 |
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195 | * |
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196 | *@endcode |
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197 | */ |
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198 | template<class point_rep, class duration_rep> |
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199 | inline |
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200 | void period<point_rep,duration_rep>::expand(const duration_rep& d) |
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201 | { |
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202 | begin_ = begin_ - d; |
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203 | last_ = last_ + d; |
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204 | } |
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205 | |
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206 | //! True if the point is inside the period, zero length periods contain no points |
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207 | template<class point_rep, class duration_rep> |
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208 | inline |
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209 | bool period<point_rep,duration_rep>::contains(const point_rep& point) const |
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210 | { |
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211 | return ((point >= begin_) && |
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212 | (point <= last_)); |
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213 | } |
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214 | |
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215 | |
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216 | //! True if this period fully contains (or equals) the other period |
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217 | template<class point_rep, class duration_rep> |
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218 | inline |
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219 | bool period<point_rep,duration_rep>::contains(const period<point_rep,duration_rep>& other) const |
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220 | { |
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221 | return ((begin_ <= other.begin_) && (last_ >= other.last_)); |
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222 | } |
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223 | |
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224 | |
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225 | //! True if periods are next to each other without a gap. |
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226 | /* In the example below, p1 and p2 are adjacent, but p3 is not adjacent |
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227 | * with either of p1 or p2. |
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228 | *@code |
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229 | * [-p1-) |
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230 | * [-p2-) |
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231 | * [-p3-) |
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232 | *@endcode |
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233 | */ |
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234 | template<class point_rep, class duration_rep> |
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235 | inline |
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236 | bool |
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237 | period<point_rep,duration_rep>::is_adjacent(const period<point_rep,duration_rep>& other) const |
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238 | { |
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239 | return (other.begin() == end() || |
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240 | begin_ == other.end()); |
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241 | } |
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242 | |
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243 | |
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244 | //! True if all of the period is prior or t < start |
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245 | /* In the example below only point 1 would evaluate to true. |
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246 | *@code |
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247 | * [---------]) |
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248 | * ^ ^ ^ ^ ^ |
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249 | * 1 2 3 4 5 |
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250 | * |
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251 | *@endcode |
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252 | */ |
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253 | template<class point_rep, class duration_rep> |
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254 | inline |
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255 | bool |
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256 | period<point_rep,duration_rep>::is_after(const point_rep& t) const |
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257 | { |
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258 | if (is_null()) |
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259 | { |
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260 | return false; //null period isn't after |
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261 | } |
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262 | |
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263 | return t < begin_; |
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264 | } |
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265 | |
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266 | //! True if all of the period is prior to the passed point or end <= t |
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267 | /* In the example below points 4 and 5 return true. |
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268 | *@code |
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269 | * [---------]) |
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270 | * ^ ^ ^ ^ ^ |
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271 | * 1 2 3 4 5 |
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272 | * |
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273 | *@endcode |
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274 | */ |
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275 | template<class point_rep, class duration_rep> |
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276 | inline |
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277 | bool |
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278 | period<point_rep,duration_rep>::is_before(const point_rep& t) const |
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279 | { |
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280 | if (is_null()) |
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281 | { |
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282 | return false; //null period isn't before anything |
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283 | } |
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284 | |
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285 | return last_ < t; |
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286 | } |
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287 | |
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288 | |
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289 | //! True if the periods overlap in any way |
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290 | /* In the example below p1 intersects with p2, p4, and p6. |
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291 | *@code |
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292 | * [---p1---) |
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293 | * [---p2---) |
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294 | * [---p3---) |
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295 | * [---p4---) |
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296 | * [-p5-) |
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297 | * [-p6-) |
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298 | *@endcode |
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299 | */ |
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300 | template<class point_rep, class duration_rep> |
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301 | inline |
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302 | bool period<point_rep,duration_rep>::intersects(const period<point_rep,duration_rep>& other) const |
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303 | { |
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304 | return ( contains(other.begin_) || |
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305 | other.contains(begin_) || |
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306 | ((other.begin_ < begin_) && (other.last_ >= begin_))); |
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307 | } |
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308 | |
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309 | //! Returns the period of intersection or invalid range no intersection |
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310 | template<class point_rep, class duration_rep> |
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311 | inline |
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312 | period<point_rep,duration_rep> |
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313 | period<point_rep,duration_rep>::intersection(const period<point_rep,duration_rep>& other) const |
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314 | { |
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315 | if (begin_ > other.begin_) { |
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316 | if (last_ <= other.last_) { //case2 |
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317 | return *this; |
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318 | } |
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319 | //case 1 |
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320 | return period<point_rep,duration_rep>(begin_, other.end()); |
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321 | } |
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322 | else { |
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323 | if (last_ <= other.last_) { //case3 |
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324 | return period<point_rep,duration_rep>(other.begin_, this->end()); |
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325 | } |
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326 | //case4 |
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327 | return other; |
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328 | } |
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329 | //unreachable |
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330 | } |
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331 | |
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332 | //! Returns the union of intersecting periods -- or null period |
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333 | /*! |
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334 | */ |
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335 | template<class point_rep, class duration_rep> |
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336 | inline |
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337 | period<point_rep,duration_rep> |
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338 | period<point_rep,duration_rep>::merge(const period<point_rep,duration_rep>& other) const |
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339 | { |
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340 | if (this->intersects(other)) { |
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341 | if (begin_ < other.begin_) { |
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342 | return period<point_rep,duration_rep>(begin_, last_ > other.last_ ? this->end() : other.end()); |
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343 | } |
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344 | |
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345 | return period<point_rep,duration_rep>(other.begin_, last_ > other.last_ ? this->end() : other.end()); |
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346 | |
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347 | } |
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348 | return period<point_rep,duration_rep>(begin_,begin_); // no intersect return null |
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349 | } |
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350 | |
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351 | //! Combine two periods with earliest start and latest end. |
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352 | /*! Combines two periods and any gap between them such that |
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353 | * start = min(p1.start, p2.start) |
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354 | * end = max(p1.end , p2.end) |
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355 | *@code |
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356 | * [---p1---) |
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357 | * [---p2---) |
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358 | * result: |
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359 | * [-----------p3----------) |
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360 | *@endcode |
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361 | */ |
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362 | template<class point_rep, class duration_rep> |
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363 | inline |
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364 | period<point_rep,duration_rep> |
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365 | period<point_rep,duration_rep>::span(const period<point_rep,duration_rep>& other) const |
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366 | { |
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367 | point_rep start((begin_ < other.begin_) ? begin() : other.begin()); |
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368 | point_rep newend((last_ < other.last_) ? other.end() : this->end()); |
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369 | return period<point_rep,duration_rep>(start, newend); |
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370 | } |
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371 | |
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372 | |
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373 | } } //namespace date_time |
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374 | |
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375 | |
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376 | |
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377 | #endif |
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