class Addressable::URI

def self.normalize_component(component, character_class=
    CharacterClasses::RESERVED + CharacterClasses::UNRESERVED,
    leave_encoded='')
  return nil if component.nil?
  begin
    component = component.to_str
  rescue NoMethodError, TypeError
    raise TypeError, "Can't convert #{component.class} into String."
  end if !component.is_a? String
  if ![String, Regexp].include?(character_class.class)
    raise TypeError,
      "Expected String or Regexp, got #{character_class.inspect}"
  end
  if character_class.kind_of?(String)
    leave_re = if leave_encoded.length > 0
      character_class = "#{character_class}%" unless character_class.include?('%')
      bytes = leave_encoded.bytes
      leave_encoded_pattern = bytes.map { |b| SEQUENCE_ENCODING_TABLE[b] }.join('|')
      "|%(?!#{leave_encoded_pattern}|#{leave_encoded_pattern.upcase})"
    end
    character_class = if leave_re
                        /[^#{character_class}]#{leave_re}/
                      else
                        /[^#{character_class}]/
                      end
  end
  # We can't perform regexps on invalid UTF sequences, but
  # here we need to, so switch to ASCII.
  component = component.dup
  component.force_encoding(Encoding::ASCII_8BIT)
  unencoded = self.unencode_component(component, String, leave_encoded)
  begin
    encoded = self.encode_component(
      unencoded.unicode_normalize(:nfc),
      character_class,
      leave_encoded
    )
  rescue ArgumentError
    encoded = self.encode_component(unencoded)
  end
  encoded.force_encoding(Encoding::UTF_8)
  return encoded
end