# File lib/execjs/johnson_runtime.rb, line 17
      def eval(source, options = {})
        source = source.encode('UTF-8') if source.respond_to?(:encode)

        if /\S/ =~ source
          unbox @runtime.evaluate("(#{source})")
        end
      rescue Johnson::Error => e
        if syntax_error?(e)
          raise RuntimeError, e.message
        else
          raise ProgramError, e.message
        end
      end