# File lib/rdoc/ri/driver.rb, line 748
  def expand_class klass
    klass.split('::').inject '' do |expanded, klass_part|
      expanded << '::' unless expanded.empty?
      short = expanded << klass_part

      subset = classes.keys.select do |klass_name|
        klass_name =~ /^#{expanded}[^:]*$/
      end

      abbrevs = Abbrev.abbrev subset

      expanded = abbrevs[short]

      raise NotFoundError, short unless expanded

      expanded.dup
    end
  end