module OracleSqlParser::Grammar::Condition

grammar Null
  rule null_condition
    expr space is_keyword space n:(not_keyword space)? null_keyword {
      def ast
        OracleSqlParser::Ast::NullCondition[
          :target => expr.ast,
          :not => not_keyword.ast]
      end

      def not_keyword
        n.elements && n.elements.first
      end
    }
  end
end

end