1 | // Copyright 2002 The Trustees of Indiana University. |
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2 | |
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3 | // Use, modification and distribution is subject to the Boost Software |
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4 | // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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5 | // http://www.boost.org/LICENSE_1_0.txt) |
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6 | |
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7 | // Boost.MultiArray Library |
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8 | // Authors: Ronald Garcia |
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9 | // Jeremy Siek |
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10 | // Andrew Lumsdaine |
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11 | // See http://www.boost.org/libs/multi_array for documentation. |
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12 | |
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13 | #ifndef BOOST_INDEX_RANGE_RG071801_HPP |
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14 | #define BOOST_INDEX_RANGE_RG071801_HPP |
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15 | |
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16 | #include <boost/config.hpp> |
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17 | #include <utility> |
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18 | #include <boost/limits.hpp> |
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19 | |
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20 | // For representing intervals, also with stride. |
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21 | // A degenerate range is a range with one element. |
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22 | |
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23 | // Thanks to Doug Gregor for the really cool idea of using the |
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24 | // comparison operators to express various interval types! |
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25 | |
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26 | // Internally, we represent the interval as half-open. |
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27 | |
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28 | namespace boost { |
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29 | namespace detail { |
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30 | namespace multi_array { |
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31 | |
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32 | template <typename Index,typename SizeType> |
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33 | class index_range { |
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34 | public: |
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35 | typedef Index index; |
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36 | typedef SizeType size_type; |
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37 | |
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38 | private: |
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39 | static index from_start() |
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40 | { return (std::numeric_limits<index>::min)(); } |
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41 | |
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42 | static index to_end() |
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43 | { return (std::numeric_limits<index>::max)(); } |
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44 | |
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45 | public: |
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46 | |
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47 | index_range() |
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48 | { |
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49 | start_ = from_start(); |
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50 | finish_ = to_end(); |
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51 | stride_ = 1; |
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52 | degenerate_ = false; |
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53 | } |
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54 | |
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55 | explicit index_range(index pos) |
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56 | { |
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57 | start_ = pos; |
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58 | finish_ = pos+1; |
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59 | stride_ = 1; |
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60 | degenerate_ = true; |
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61 | } |
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62 | |
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63 | explicit index_range(index start, index finish, index stride=1) |
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64 | : start_(start), finish_(finish), stride_(stride), |
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65 | degenerate_(false) |
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66 | { } |
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67 | |
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68 | |
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69 | // These are for chaining assignments to an index_range |
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70 | index_range& start(index s) { |
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71 | start_ = s; |
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72 | degenerate_ = false; |
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73 | return *this; |
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74 | } |
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75 | |
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76 | index_range& finish(index f) { |
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77 | finish_ = f; |
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78 | degenerate_ = false; |
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79 | return *this; |
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80 | } |
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81 | |
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82 | index_range& stride(index s) { stride_ = s; return *this; } |
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83 | |
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84 | index start() const |
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85 | { |
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86 | return start_; |
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87 | } |
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88 | |
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89 | index get_start(index low_index_range = index_range::from_start()) const |
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90 | { |
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91 | if (start_ == from_start()) |
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92 | return low_index_range; |
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93 | return start_; |
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94 | } |
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95 | |
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96 | index finish() const |
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97 | { |
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98 | return finish_; |
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99 | } |
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100 | |
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101 | index get_finish(index high_index_range = index_range::to_end()) const |
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102 | { |
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103 | if (finish_ == to_end()) |
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104 | return high_index_range; |
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105 | return finish_; |
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106 | } |
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107 | |
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108 | index stride() const { return stride_; } |
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109 | |
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110 | void set_index_range(index start, index finish, index stride=1) |
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111 | { |
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112 | start_ = start; |
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113 | finish_ = finish; |
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114 | stride_ = stride; |
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115 | } |
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116 | |
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117 | static index_range all() |
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118 | { return index_range(from_start(), to_end(), 1); } |
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119 | |
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120 | bool is_degenerate() const { return degenerate_; } |
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121 | |
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122 | index_range operator-(index shift) const |
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123 | { |
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124 | return index_range(start_ - shift, finish_ - shift, stride_); |
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125 | } |
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126 | |
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127 | index_range operator+(index shift) const |
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128 | { |
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129 | return index_range(start_ + shift, finish_ + shift, stride_); |
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130 | } |
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131 | |
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132 | index operator[](unsigned i) const |
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133 | { |
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134 | return start_ + i * stride_; |
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135 | } |
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136 | |
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137 | index operator()(unsigned i) const |
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138 | { |
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139 | return start_ + i * stride_; |
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140 | } |
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141 | |
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142 | // add conversion to std::slice? |
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143 | |
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144 | public: |
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145 | index start_, finish_, stride_; |
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146 | bool degenerate_; |
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147 | }; |
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148 | |
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149 | // Express open and closed interval end-points using the comparison |
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150 | // operators. |
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151 | |
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152 | // left closed |
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153 | template <typename Index, typename SizeType> |
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154 | inline index_range<Index,SizeType> |
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155 | operator<=(Index s, const index_range<Index,SizeType>& r) |
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156 | { |
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157 | return index_range<Index,SizeType>(s, r.finish(), r.stride()); |
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158 | } |
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159 | |
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160 | // left open |
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161 | template <typename Index, typename SizeType> |
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162 | inline index_range<Index,SizeType> |
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163 | operator<(Index s, const index_range<Index,SizeType>& r) |
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164 | { |
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165 | return index_range<Index,SizeType>(s + 1, r.finish(), r.stride()); |
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166 | } |
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167 | |
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168 | // right open |
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169 | template <typename Index, typename SizeType> |
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170 | inline index_range<Index,SizeType> |
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171 | operator<(const index_range<Index,SizeType>& r, Index f) |
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172 | { |
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173 | return index_range<Index,SizeType>(r.start(), f, r.stride()); |
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174 | } |
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175 | |
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176 | // right closed |
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177 | template <typename Index, typename SizeType> |
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178 | inline index_range<Index,SizeType> |
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179 | operator<=(const index_range<Index,SizeType>& r, Index f) |
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180 | { |
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181 | return index_range<Index,SizeType>(r.start(), f + 1, r.stride()); |
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182 | } |
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183 | |
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184 | } // namespace multi_array |
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185 | } // namespace detail |
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186 | } // namespace boost |
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187 | |
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188 | #endif // BOOST_INDEX_RANGE_RG071801_HPP |
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