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: rfc2396_parser.rb
    path of file: ./repos/ruby-packer/ruby/lib/uri
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
#--
# = uri/common.rb
#
# Author:: Akira Yamada <akira@ruby-lang.org>
# Revision:: $Id$
# License::
#   You can redistribute it and/or modify it under the same term as Ruby.
#
# See URI for general documentation
#

module URI
  #
  # Includes URI::REGEXP::PATTERN
  #
  module RFC2396_REGEXP
    #
    # Patterns used to parse URI's
    #
    module PATTERN
      # :stopdoc:

      # RFC 2396 (URI Generic Syntax)
      # RFC 2732 (IPv6 Literal Addresses in URL's)
      # RFC 2373 (IPv6 Addressing Architecture)

      # alpha         = lowalpha | upalpha
      ALPHA = "a-zA-Z"
      # alphanum      = alpha | digit
      ALNUM =
    
    def initialize_regexp(pattern)
      ret = {}

      # for URI::split
      ret[:ABS_URI] = Regexp.new('\A\s*' + pattern[:X_ABS_URI] + '\s*\z', Regexp::EXTENDED)
      ret[:REL_URI] = Regexp.new('\A\s*' + pattern[:X_REL_URI] + '\s*\z', Regexp::EXTENDED)

      # for URI::extract
      ret[:URI_REF]     = Regexp.new(pattern[:URI_REF])
      ret[:ABS_URI_REF] = Regexp.new(pattern[:X_ABS_URI], Regexp::EXTENDED)
      ret[:REL_URI_REF] = Regexp.new(pattern[:X_REL_URI], Regexp::EXTENDED)

      # for URI::escape/unescape
      ret[:ESCAPED] = Regexp.new(pattern[:ESCAPED])
      ret[:UNSAFE]  = Regexp.new("[^#{pattern[:UNRESERVED]}#{pattern[:RESERVED]}]")

      # for Generic#initialize
      ret[:SCHEME]   = Regexp.new("\\A#{pattern[:SCHEME]}\\z")
      ret[:USERINFO] = Regexp.new("\\A#{pattern[:USERINFO]}\\z")
      ret[:HOST]     = Regexp.new("\\A#{pattern[:HOST]}\\z")
      ret[:PORT]     = Regexp.new("\\A#{pattern[:PORT]}\\z")
      ret[:OPAQUE]   = Regexp.new("\\A#{pattern[:OPAQUE_PART]}\\z")
      ret[:REGISTRY] = Regexp.new("\\A#{pattern[:REG_NAME]}\\z")
      ret[:ABS_PATH] = Regexp.new("\\A#{pattern[:ABS_PATH]}\\z")
      ret[:REL_PATH] = Regexp.new("\\A#{pattern[:REL_PATH]}\\z")
      ret[:QUERY]    = Regexp.new("\\A#{pattern[:QUERY]}\\z")
      ret[:FRAGMENT] = Regexp.new("\\A#{pattern[:FRAGMENT]}\\z")

      ret
    end