path: root/lib/arel/algebra/predicates.rb

module Arel
  class Predicate
    def or(other_predicate)
      Or.new(self, other_predicate)
    end

    def and(other_predicate)
      And.new(self, other_predicate)
    end
  end

  class Binary < Predicate
    attributes :operand1, :operand2
    deriving :initialize

    def ==(other)
      self.class === other          and
      @operand1  ==  other.operand1 and
      @operand2  ==  other.operand2
    end

    def bind(relation)
      self.class.new(operand1.find_correlate_in(relation), operand2.find_correlate_in(relation))
    end
  end

  class Equality < Binary
    def ==(other)
      Equality === other and
        ((operand1 == other.operand1 and operand2 == other.operand2) or
         (operand1 == other.operand2 and operand2 == other.operand1))
    end
  end

  class GreaterThanOrEqualTo  < Binary; end
  class GreaterThan           < Binary; end
  class LessThanOrEqualTo     < Binary; end
  class LessThan              < Binary; end
  class Match                 < Binary; end
  class In                    < Binary; end
end