123 lines
2.6 KiB
Ruby
123 lines
2.6 KiB
Ruby
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# encoding: utf-8
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# Define equality, equivalence and inspection methods
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class Equalizer < Module
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# Initialize an Equalizer with the given keys
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#
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# Will use the keys with which it is initialized to define #cmp?,
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# #hash, and #inspect
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#
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# @param [Array<Symbol>] keys
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#
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# @return [undefined]
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#
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# @api private
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def initialize(*keys)
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@keys = keys
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define_methods
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freeze
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end
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private
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# Hook called when module is included
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#
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# @param [Module] descendant
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# the module or class including Equalizer
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#
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# @return [self]
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#
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# @api private
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def included(descendant)
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super
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descendant.module_eval { include Methods }
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end
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# Define the equalizer methods based on #keys
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#
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# @return [undefined]
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#
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# @api private
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def define_methods
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define_cmp_method
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define_hash_method
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define_inspect_method
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end
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# Define an #cmp? method based on the instance's values identified by #keys
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#
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# @return [undefined]
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#
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# @api private
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def define_cmp_method
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keys = @keys
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define_method(:cmp?) do |comparator, other|
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keys.all? { |key| send(key).send(comparator, other.send(key)) }
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end
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private :cmp?
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end
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# Define a #hash method based on the instance's values identified by #keys
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#
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# @return [undefined]
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#
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# @api private
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def define_hash_method
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keys = @keys
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define_method(:hash) do ||
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keys.map(&method(:send)).push(self.class).hash
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end
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end
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# Define an inspect method that reports the values of the instance's keys
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#
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# @return [undefined]
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#
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# @api private
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def define_inspect_method
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keys = @keys
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define_method(:inspect) do ||
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klass = self.class
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name = klass.name || klass.inspect
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"#<#{name}#{keys.map { |key| " #{key}=#{send(key).inspect}" }.join}>"
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end
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end
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# The comparison methods
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module Methods
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# Compare the object with other object for equality
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#
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# @example
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# object.eql?(other) # => true or false
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#
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# @param [Object] other
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# the other object to compare with
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#
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# @return [Boolean]
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#
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# @api public
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def eql?(other)
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instance_of?(other.class) && cmp?(__method__, other)
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end
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# Compare the object with other object for equivalency
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#
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# @example
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# object == other # => true or false
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#
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# @param [Object] other
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# the other object to compare with
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#
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# @return [Boolean]
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#
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# @api public
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def ==(other)
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other = coerce(other) if respond_to?(:coerce, true)
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other.kind_of?(self.class) && cmp?(__method__, other)
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end
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end # module Methods
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end # class Equalizer
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