class IO

The expect library adds instance method IO#expect, which is similar to the TCL expect extension.

To use this method, you must require expect:

require 'expect'

Reads from the IO until the given pattern matches or the timeout is over.

It returns an array with the read buffer, followed by the matches. If a block is given, the result is yielded to the block and returns nil.

When called without a block, it waits until the input that matches the given pattern is obtained from the IO or the time specified as the timeout passes. An array is returned when the pattern is obtained from the IO. The first element of the array is the entire string obtained from the IO until the pattern matches, followed by elements indicating which the pattern which matched to the anchor in the regular expression.

The optional timeout parameter defines, in seconds, the total time to wait for the pattern. If the timeout expires or eof is found, nil is returned or yielded. However, the buffer in a timeout session is kept for the next expect call. The default timeout is 9999999 seconds.

# File pty/lib/expect.rb, line 33
def expect(pat,timeout=9999999)
  buf = ''.dup
  case pat
  when String
    e_pat = Regexp.new(Regexp.quote(pat))
  when Regexp
    e_pat = pat
  else
    raise TypeError, "unsupported pattern class: #{pat.class}"
  end
  @unusedBuf ||= ''
  while true
    if not @unusedBuf.empty?
      c = @unusedBuf.slice!(0)
    elsif !IO.select([self],nil,nil,timeout) or eof? then
      result = nil
      @unusedBuf = buf
      break
    else
      c = getc
    end
    buf << c
    if $expect_verbose
      STDOUT.print c
      STDOUT.flush
    end
    if mat=e_pat.match(buf) then
      result = [buf,*mat.captures]
      break
    end
  end
  if block_given? then
    yield result
  else
    return result
  end
  nil
end