# File rexml/source.rb, line 134
    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 0xfe == str[0] && 0xff == str[1]
        @line_break = "\000>"
      elsif 0xff == str[0] && 0xfe == str[1]
        @line_break = ">\000"
      elsif 0xef == str[0] && 0xbb == str[1]
        str += @source.read(1)
        str = '' if (0xbf == str[2])
        @line_break = ">"
      else
        @line_break = ">"
      end
      super str+@source.readline( @line_break )
    end

# File rexml/source.rb, line 200
    def consume( pattern )
      match( pattern, true )
    end

# File rexml/source.rb, line 231
    def current_line
      begin
        pos = @er_source.pos        # The byte position in the source
        lineno = @er_source.lineno  # The XML < position in the source
        @er_source.rewind
        line = 0                    # The \r\n position in the source
        begin
          while @er_source.pos < pos
            @er_source.readline
            line += 1
          end
        rescue
        end
      rescue IOError
        pos = -1
        line = -1
      end
      [pos, lineno, line]
    end

# File rexml/source.rb, line 222
    def empty?
      super and ( @source.nil? || @source.eof? )
    end

# File rexml/source.rb, line 204
    def match( pattern, cons=false )
      rv = pattern.match(@buffer)
      @buffer = $' if cons and rv
      while !rv and @source
        begin
          str = @source.readline(@line_break)
          str = decode(str) if @to_utf and str
          @buffer << str
          rv = pattern.match(@buffer)
          @buffer = $' if cons and rv
        rescue
          @source = nil
        end
      end
      rv.taint
      rv
    end

# File rexml/source.rb, line 226
    def position
      @er_source.stat.pipe? ? 0 : @er_source.pos
    end

# File rexml/source.rb, line 190
    def read
      begin
        str = @source.readline(@line_break)
        str = decode(str) if @to_utf and str 
        @buffer << str
      rescue Exception, NameError
        @source = nil
      end
    end

# File rexml/source.rb, line 163
    def scan(pattern, cons=false)
      rv = super
      # You'll notice that this next section is very similar to the same
      # section in match(), but just a liiittle different.  This is
      # because it is a touch faster to do it this way with scan()
      # than the way match() does it; enough faster to warrent duplicating
      # some code
      if rv.size == 0
        until @buffer =~ pattern or @source.nil?
          begin
            # READLINE OPT
            #str = @source.read(@block_size)
            str = @source.readline(@line_break)
            str = decode(str) if @to_utf and str
            @buffer << str
          rescue Iconv::IllegalSequence
            raise
          rescue
            @source = nil
          end
        end
        rv = super
      end
      rv.taint
      rv
    end