1 | class Hash
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2 |
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3 | # ISO does not define Hash#each_pair, so each_pair is defined in gem.
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4 | alias each_pair each
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5 |
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6 | ##
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7 | # call-seq:
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8 | # Hash[ key, value, ... ] -> new_hash
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9 | # Hash[ [ [key, value], ... ] ] -> new_hash
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10 | # Hash[ object ] -> new_hash
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11 | #
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12 | # Creates a new hash populated with the given objects.
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13 | #
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14 | # Similar to the literal `{ _key_ => _value_, ... }`. In the first
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15 | # form, keys and values occur in pairs, so there must be an even number of
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16 | # arguments.
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17 | #
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18 | # The second and third form take a single argument which is either an array
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19 | # of key-value pairs or an object convertible to a hash.
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20 | #
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21 | # Hash["a", 100, "b", 200] #=> {"a"=>100, "b"=>200}
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22 | # Hash[ [ ["a", 100], ["b", 200] ] ] #=> {"a"=>100, "b"=>200}
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23 | # Hash["a" => 100, "b" => 200] #=> {"a"=>100, "b"=>200}
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24 | #
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25 |
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26 | def self.[](*object)
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27 | length = object.length
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28 | if length == 1
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29 | o = object[0]
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30 | if o.respond_to?(:to_hash)
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31 | h = Hash.new
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32 | object[0].to_hash.each { |k, v| h[k] = v }
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33 | return h
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34 | elsif o.respond_to?(:to_a)
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35 | h = Hash.new
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36 | o.to_a.each do |i|
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37 | raise ArgumentError, "wrong element type #{i.class} (expected array)" unless i.respond_to?(:to_a)
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38 | k, v = nil
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39 | case i.size
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40 | when 2
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41 | k = i[0]
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42 | v = i[1]
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43 | when 1
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44 | k = i[0]
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45 | else
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46 | raise ArgumentError, "invalid number of elements (#{i.size} for 1..2)"
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47 | end
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48 | h[k] = v
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49 | end
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50 | return h
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51 | end
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52 | end
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53 | unless length % 2 == 0
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54 | raise ArgumentError, 'odd number of arguments for Hash'
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55 | end
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56 | h = Hash.new
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57 | 0.step(length - 2, 2) do |i|
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58 | h[object[i]] = object[i + 1]
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59 | end
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60 | h
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61 | end
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62 |
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63 | ##
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64 | # call-seq:
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65 | # hsh.merge!(other_hash) -> hsh
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66 | # hsh.merge!(other_hash){|key, oldval, newval| block} -> hsh
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67 | #
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68 | # Adds the contents of _other_hash_ to _hsh_. If no block is specified,
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69 | # entries with duplicate keys are overwritten with the values from
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70 | # _other_hash_, otherwise the value of each duplicate key is determined by
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71 | # calling the block with the key, its value in _hsh_ and its value in
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72 | # _other_hash_.
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73 | #
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74 | # h1 = { "a" => 100, "b" => 200 }
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75 | # h2 = { "b" => 254, "c" => 300 }
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76 | # h1.merge!(h2) #=> {"a"=>100, "b"=>254, "c"=>300}
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77 | #
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78 | # h1 = { "a" => 100, "b" => 200 }
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79 | # h2 = { "b" => 254, "c" => 300 }
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80 | # h1.merge!(h2) { |key, v1, v2| v1 }
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81 | # #=> {"a"=>100, "b"=>200, "c"=>300}
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82 | #
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83 |
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84 | def merge!(other, &block)
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85 | raise TypeError, "can't convert argument into Hash" unless other.respond_to?(:to_hash)
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86 | if block
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87 | other.each_key{|k|
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88 | self[k] = (self.has_key?(k))? block.call(k, self[k], other[k]): other[k]
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89 | }
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90 | else
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91 | other.each_key{|k| self[k] = other[k]}
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92 | end
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93 | self
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94 | end
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95 |
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96 | alias update merge!
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97 |
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98 | ##
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99 | # call-seq:
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100 | # hsh.fetch(key [, default] ) -> obj
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101 | # hsh.fetch(key) {| key | block } -> obj
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102 | #
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103 | # Returns a value from the hash for the given key. If the key can't be
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104 | # found, there are several options: With no other arguments, it will
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105 | # raise an <code>KeyError</code> exception; if <i>default</i> is
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106 | # given, then that will be returned; if the optional code block is
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107 | # specified, then that will be run and its result returned.
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108 | #
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109 | # h = { "a" => 100, "b" => 200 }
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110 | # h.fetch("a") #=> 100
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111 | # h.fetch("z", "go fish") #=> "go fish"
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112 | # h.fetch("z") { |el| "go fish, #{el}"} #=> "go fish, z"
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113 | #
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114 | # The following example shows that an exception is raised if the key
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115 | # is not found and a default value is not supplied.
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116 | #
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117 | # h = { "a" => 100, "b" => 200 }
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118 | # h.fetch("z")
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119 | #
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120 | # <em>produces:</em>
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121 | #
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122 | # prog.rb:2:in 'fetch': key not found (KeyError)
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123 | # from prog.rb:2
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124 | #
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125 |
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126 | def fetch(key, none=NONE, &block)
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127 | unless self.key?(key)
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128 | if block
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129 | block.call(key)
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130 | elsif none != NONE
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131 | none
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132 | else
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133 | raise KeyError, "Key not found: #{key}"
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134 | end
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135 | else
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136 | self[key]
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137 | end
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138 | end
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139 |
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140 | ##
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141 | # call-seq:
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142 | # hsh.delete_if {| key, value | block } -> hsh
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143 | # hsh.delete_if -> an_enumerator
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144 | #
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145 | # Deletes every key-value pair from <i>hsh</i> for which <i>block</i>
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146 | # evaluates to <code>true</code>.
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147 | #
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148 | # If no block is given, an enumerator is returned instead.
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149 | #
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150 | # h = { "a" => 100, "b" => 200, "c" => 300 }
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151 | # h.delete_if {|key, value| key >= "b" } #=> {"a"=>100}
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152 | #
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153 |
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154 | def delete_if(&block)
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155 | return to_enum :delete_if unless block_given?
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156 |
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157 | self.each do |k, v|
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158 | self.delete(k) if block.call(k, v)
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159 | end
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160 | self
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161 | end
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162 |
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163 | ##
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164 | # call-seq:
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165 | # hash.flatten -> an_array
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166 | # hash.flatten(level) -> an_array
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167 | #
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168 | # Returns a new array that is a one-dimensional flattening of this
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169 | # hash. That is, for every key or value that is an array, extract
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170 | # its elements into the new array. Unlike Array#flatten, this
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171 | # method does not flatten recursively by default. The optional
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172 | # <i>level</i> argument determines the level of recursion to flatten.
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173 | #
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174 | # a = {1=> "one", 2 => [2,"two"], 3 => "three"}
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175 | # a.flatten # => [1, "one", 2, [2, "two"], 3, "three"]
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176 | # a.flatten(2) # => [1, "one", 2, 2, "two", 3, "three"]
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177 | #
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178 |
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179 | def flatten(level=1)
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180 | self.to_a.flatten(level)
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181 | end
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182 |
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183 | ##
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184 | # call-seq:
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185 | # hsh.invert -> new_hash
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186 | #
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187 | # Returns a new hash created by using <i>hsh</i>'s values as keys, and
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188 | # the keys as values.
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189 | #
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190 | # h = { "n" => 100, "m" => 100, "y" => 300, "d" => 200, "a" => 0 }
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191 | # h.invert #=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"}
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192 | #
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193 |
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194 | def invert
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195 | h = Hash.new
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196 | self.each {|k, v| h[v] = k }
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197 | h
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198 | end
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199 |
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200 | ##
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201 | # call-seq:
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202 | # hsh.keep_if {| key, value | block } -> hsh
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203 | # hsh.keep_if -> an_enumerator
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204 | #
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205 | # Deletes every key-value pair from <i>hsh</i> for which <i>block</i>
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206 | # evaluates to false.
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207 | #
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208 | # If no block is given, an enumerator is returned instead.
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209 | #
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210 |
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211 | def keep_if(&block)
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212 | return to_enum :keep_if unless block_given?
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213 |
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214 | keys = []
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215 | self.each do |k, v|
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216 | unless block.call([k, v])
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217 | self.delete(k)
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218 | end
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219 | end
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220 | self
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221 | end
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222 |
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223 | ##
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224 | # call-seq:
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225 | # hsh.key(value) -> key
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226 | #
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227 | # Returns the key of an occurrence of a given value. If the value is
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228 | # not found, returns <code>nil</code>.
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229 | #
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230 | # h = { "a" => 100, "b" => 200, "c" => 300, "d" => 300 }
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231 | # h.key(200) #=> "b"
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232 | # h.key(300) #=> "c"
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233 | # h.key(999) #=> nil
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234 | #
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235 |
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236 | def key(val)
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237 | self.each do |k, v|
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238 | return k if v == val
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239 | end
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240 | nil
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241 | end
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242 |
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243 | ##
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244 | # call-seq:
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245 | # hsh.to_h -> hsh or new_hash
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246 | #
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247 | # Returns +self+. If called on a subclass of Hash, converts
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248 | # the receiver to a Hash object.
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249 | #
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250 | def to_h
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251 | self
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252 | end
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253 |
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254 | ##
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255 | # call-seq:
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256 | # hash < other -> true or false
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257 | #
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258 | # Returns <code>true</code> if <i>hash</i> is subset of
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259 | # <i>other</i>.
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260 | #
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261 | # h1 = {a:1, b:2}
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262 | # h2 = {a:1, b:2, c:3}
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263 | # h1 < h2 #=> true
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264 | # h2 < h1 #=> false
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265 | # h1 < h1 #=> false
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266 | #
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267 | def <(hash)
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268 | begin
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269 | hash = hash.to_hash
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270 | rescue NoMethodError
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271 | raise TypeError, "can't convert #{hash.class} to Hash"
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272 | end
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273 | size < hash.size and all? {|key, val|
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274 | hash.key?(key) and hash[key] == val
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275 | }
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276 | end
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277 |
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278 | ##
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279 | # call-seq:
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280 | # hash <= other -> true or false
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281 | #
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282 | # Returns <code>true</code> if <i>hash</i> is subset of
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283 | # <i>other</i> or equals to <i>other</i>.
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284 | #
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285 | # h1 = {a:1, b:2}
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286 | # h2 = {a:1, b:2, c:3}
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287 | # h1 <= h2 #=> true
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288 | # h2 <= h1 #=> false
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289 | # h1 <= h1 #=> true
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290 | #
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291 | def <=(hash)
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292 | begin
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293 | hash = hash.to_hash
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294 | rescue NoMethodError
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295 | raise TypeError, "can't convert #{hash.class} to Hash"
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296 | end
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297 | size <= hash.size and all? {|key, val|
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298 | hash.key?(key) and hash[key] == val
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299 | }
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300 | end
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301 |
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302 | ##
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303 | # call-seq:
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304 | # hash > other -> true or false
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305 | #
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306 | # Returns <code>true</code> if <i>other</i> is subset of
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307 | # <i>hash</i>.
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308 | #
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309 | # h1 = {a:1, b:2}
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310 | # h2 = {a:1, b:2, c:3}
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311 | # h1 > h2 #=> false
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312 | # h2 > h1 #=> true
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313 | # h1 > h1 #=> false
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314 | #
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315 | def >(hash)
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316 | begin
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317 | hash = hash.to_hash
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318 | rescue NoMethodError
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319 | raise TypeError, "can't convert #{hash.class} to Hash"
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320 | end
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321 | size > hash.size and hash.all? {|key, val|
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322 | key?(key) and self[key] == val
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323 | }
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324 | end
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325 |
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326 | ##
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327 | # call-seq:
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328 | # hash >= other -> true or false
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329 | #
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330 | # Returns <code>true</code> if <i>other</i> is subset of
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331 | # <i>hash</i> or equals to <i>hash</i>.
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332 | #
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333 | # h1 = {a:1, b:2}
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334 | # h2 = {a:1, b:2, c:3}
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335 | # h1 >= h2 #=> false
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336 | # h2 >= h1 #=> true
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337 | # h1 >= h1 #=> true
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338 | #
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339 | def >=(hash)
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340 | begin
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341 | hash = hash.to_hash
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342 | rescue NoMethodError
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343 | raise TypeError, "can't convert #{hash.class} to Hash"
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344 | end
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345 | size >= hash.size and hash.all? {|key, val|
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346 | key?(key) and self[key] == val
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347 | }
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348 | end
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349 | end
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