abbreviate (REXML::Parsers::XPathParser)

    # File temp/parsers/xpathparser.rb, line 33
          def abbreviate( path )
            path = path.kind_of?(String) ? parse( path ) : path
            string = ""
            document = false
            while path.size > 0
              op = path.shift
              case op
              when :node
              when :attribute
                string << "@"
              when :child
                string << "/"
              when :descendant_or_self
                string << "/"
              when :self
                string << "."
              when :parent
                string << ".."
              when :any
                string << "*"
              when :following, :following_sibling,
                    :ancestor, :ancestor_or_self, :descendant,
                    :namespace, :preceding, :preceding_sibling
                string << "/" unless string.size == 0
                string << op.to_s.tr("_", "-")
                string << "::"
              when :qname
                prefix = path.shift
                name = path.shift
                string << prefix+":" if prefix.size > 0
                string << name
              when :predicate
                string << '['
                string << predicate_to_string( path.shift ) {|x| abbreviate( x ) }
                string << ']'
              when :document
                document = true
              else
                string << "/" unless string.size == 0
                string << "UNKNOWN("
                string << op.inspect
                string << ")"
              end
            end
            return string
          end