class IRB::StdioInputMethod

def eof?

See IO#eof? for more information.

there is no more data to read.
Whether the end of this input method has been reached, returns +true+ if 
def eof?
  if @stdin.wait_readable(0.00001)
    c = @stdin.getc
    result = c.nil? ? true : false
    @stdin.ungetc(c) unless c.nil?
    result
  else # buffer is empty
    false
  end
end