Contents

# encoding: utf-8

module Selector

  # Describe an immutable condition for selecting values
  #
  class Condition

    include Comparable

    # @!attribute [r] attributes
    #
    # @return [Array] The array of initialized attributes
    #
    attr_reader :attributes

    # The first attribute
    #
    # @return [Object]
    #
    def attribute
      attributes.first
    end

    # @private
    def initialize(*attributes)
      @attributes = attributes
      IceNine.deep_freeze(self)
    end

    # Compares the condition to the other object by type and attributes
    #
    # @param [Object] other
    #
    # @return [Boolean]
    #
    def ==(other)
      other.instance_of?(self.class) && attributes.eql?(other.attributes)
    end
    alias_method :eql?, :==

    # @!method [](value)
    # Checks if the value satisfies the condtion
    #
    # @param [Object] value
    #
    # @return [Boolean]
    #
    # @abstract
    # @raise [NotImplementedError] by default
    #
    def [](_value)
      fail NotImplementedError.new "#{self.class}#[] not implemented"
    end

    # Inverts the condition
    #
    # @return [Selector::Condition]
    #
    def !
      Not.new(self)
    end

    # Composes (by AND) the condition to the other condition
    #
    # @param [Selector::Condition] other
    #
    # @return [Selector::Condition]
    #
    def &(other)
      And.new(self, other)
    end

    # Composes (by AND) the condition to inversion of the other condition
    #
    # This is the same as `&(!other)`
    #
    # @param [Selector::Condition] other
    #
    # @return [Selector::Condition]
    #
    def -(other)
      And.new(self, !other)
    end

    # Composes (by OR) the condition to the other condition
    #
    # This is the same as `!((!self)&(!other))`
    #
    # @param [Selector::Condition] other
    #
    # @return [Selector::Condition]
    #
    def |(other)
      Or.new(self, other)
    end

  end # class Condition

end # module Selector

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
selector-0.0.3	lib/selector/condition.rb