You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: xpathparser.rb
    path of file: ./repos/truffleruby/lib/gems/gems/rexml-3.2.5/lib/rexml/parsers
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
require_relative '../namespace'
require_relative '../xmltokens'

module REXML
  module Parsers
    # You don't want to use this class.  Really.  Use XPath, w
    
      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 << "/" if string.size > 0
            string << "@"
          when :child
            string << "/" if string.size > 0
          when :descendant_or_self
            string << "/"
          when :self
            string << "."
          when :parent
            string << ".."
          when :any
            string << "*"
          when :text
            string << "text()"
          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
          when :function
            string << path.shift
            string << "( "
            string << predicate_to_string( path.shift[0] ) {|x| abbreviate( x )}
            string << " )"
          when :literal
            string << %Q{ "#{path.shift}" }
          else
            string << "/" unless string.size == 0
            string << "UNKNOWN("
            string << op.inspect
            string << ")"
          end