# File lib/execjs/ruby_rhino_runtime.rb, line 22
      def eval(source, options = {})
        source = encode(source)

        if /\S/ =~ source
          unbox @rhino_context.eval("(#{source})")
        end
      rescue ::Rhino::JSError => e
        if e.message =~ /^syntax error/
          raise RuntimeError, e.message
        else
          raise ProgramError, e.message
        end
      end