const_regexp

# File activesupport/lib/active_support/inflector/methods.rb, line 355
    def const_regexp(camel_cased_word) #:nodoc:
      parts = camel_cased_word.split("::")

      return Regexp.escape(camel_cased_word) if parts.blank?

      last  = parts.pop

      parts.reverse.inject(last) do |acc, part|
        part.empty? ? acc : "#{part}(::#{acc})?"
      end
    end