new

# File lib/rexml/source.rb, line 136
    def initialize(arg, block_size=500, encoding=nil)
      @er_source = @source = arg
      @to_utf = false

      # Determining the encoding is a deceptively difficult issue to resolve.
      # First, we check the first two bytes for UTF-16.  Then we
      # assume that the encoding is at least ASCII enough for the '>', and
      # we read until we get one of those.  This gives us the XML declaration,
      # if there is one.  If there isn't one, the file MUST be UTF-8, as per
      # the XML spec.  If there is one, we can determine the encoding from
      # it.
      @buffer = ""
      str = @source.read( 2 ) || ''
      if encoding
        self.encoding = encoding
      elsif str[0,2] == "\xfe\xff"
        @line_break = "\0000>"
      elsif str[0,2] == "\xff\xfe"
        @line_break = ">\0000"
      elsif str[0,2] == "\xef\xbb"
        str += @source.read(1)
        str = '' if (str[2,1] == "\xBF")
        @line_break = ">"
      else
        @line_break = ">"
      end
      super( @source.eof? ? str : str+@source.readline( @line_break ) )

      if !@to_utf and
          @buffer.respond_to?(:force_encoding) and
          @source.respond_to?(:external_encoding) and
          @source.external_encoding != ::Encoding::UTF_8
        @force_utf8 = true
      else
        @force_utf8 = false
      end
    end