visit_String

# File ext/psych/lib/psych/visitors/yaml_tree.rb, line 276
      def visit_String o
        plain = true
        quote = true
        style = Nodes::Scalar::PLAIN
        tag   = nil
        str   = o

        if binary?(o)
          str   = [o].pack('m').chomp
          tag   = '!binary' # FIXME: change to below when syck is removed
          #tag   = 'tag:yaml.org,2002:binary'
          style = Nodes::Scalar::LITERAL
          plain = false
          quote = false
        elsif o =~ /\n/
          style = Nodes::Scalar::LITERAL
        elsif o =~ /^\W[^"]*$/
          style = Nodes::Scalar::DOUBLE_QUOTED
        else
          unless String === @ss.tokenize(o)
            style = Nodes::Scalar::SINGLE_QUOTED
          end
        end

        ivars = find_ivars o

        if ivars.empty?
          unless o.class == ::String
            tag = "!ruby/string:#{o.class}"
            plain = false
            quote = false
          end
          @emitter.scalar str, nil, tag, plain, quote, style
        else
          maptag = '!ruby/string'
          maptag << ":#{o.class}" unless o.class == ::String

          register o, @emitter.start_mapping(nil, maptag, false, Nodes::Mapping::BLOCK)
          @emitter.scalar 'str', nil, nil, true, false, Nodes::Scalar::ANY
          @emitter.scalar str, nil, tag, plain, quote, style

          dump_ivars o

          @emitter.end_mapping
        end
      end