class REXML::Parsers::BaseParser

def process_instruction
  name = parse_name("Malformed XML: Invalid processing instruction node")
  if @source.match?(/\s+/um, true)
    match_data = @source.match(/(.*?)\?>/um, true)
    unless match_data
      raise ParseException.new("Malformed XML: Unclosed processing instruction", @source)
    end
    content = match_data[1]
  else
    content = nil
    unless @source.match?("?>", true)
      raise ParseException.new("Malformed XML: Unclosed processing instruction", @source)
    end
  end
  if name == "xml"
    if @document_status
      raise ParseException.new("Malformed XML: XML declaration is not at the start", @source)
    end
    version = VERSION.match(content)
    version = version[1] unless version.nil?
    encoding = ENCODING.match(content)
    encoding = encoding[1] unless encoding.nil?
    if need_source_encoding_update?(encoding)
      @source.encoding = encoding
    end
    if encoding.nil? and /\AUTF-16(?:BE|LE)\z/i =~ @source.encoding
      encoding = "UTF-16"
    end
    standalone = STANDALONE.match(content)
    standalone = standalone[1] unless standalone.nil?
    return [ :xmldecl, version, encoding, standalone ]
  end
  [:processing_instruction, name, content]
end