value_check

# File actionpack/lib/action_controller/routing/segments.rb, line 148
      def value_check
        if default # Then we know it won't be nil
          "#{value_regexp.inspect} =~ #{local_name}" if regexp
        elsif optional?
          # If we have a regexp check that the value is not given, or that it matches.
          # If we have no regexp, return nil since we do not require a condition.
          "#{local_name}.nil? || #{value_regexp.inspect} =~ #{local_name}" if regexp
        else # Then it must be present, and if we have a regexp, it must match too.
          "#{local_name} #{"&& #{value_regexp.inspect} =~ #{local_name}" if regexp}"
        end
      end