set_encoding

# File lib/rdoc/encoding.rb, line 73
  def self.set_encoding string
    first_line = string[/\A(?:#!.*\n)?.*\n/]

    name = case first_line
           when /^<\?xml[^?]*encoding=(["'])(.*?)\11// then $2
           when /\b(?:en)?coding[=:]\s*([^\s;]+)/   then $1
           else                                           return
           end

    string.sub! first_line, ''

    return unless Object.const_defined? :Encoding

    enc = Encoding.find name
    string.force_encoding enc if enc
  end