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# Sourced from Ruby's ext/pty/lib/expect.rb to allow for access from Windows,
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# which does not seem to have an issue using this particular method with
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# sockets (pipes and other handles won't work, so don't use it for that).
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# frozen_string_literal: true
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$expect_verbose = false
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# Expect library adds the IO instance method #expect, which does similar act to
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# tcl's expect extension.
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#
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# In order to use this method, you must require expect:
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#
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#   require 'expect'
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#
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# Please see #expect for usage.
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class IO
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  # call-seq:
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  #   IO#expect(pattern,timeout=9999999)                  ->  Array
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  #   IO#expect(pattern,timeout=9999999) { |result| ... } ->  nil
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  #
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  # Reads from the IO until the given +pattern+ matches or the +timeout+ is over.
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  #
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  # It returns an array with the read buffer, followed by the matches.
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  # If a block is given, the result is yielded to the block and returns nil.
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  #
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  # When called without a block, it waits until the input that matches the
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  # given +pattern+ is obtained from the IO or the time specified as the
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  # timeout passes. An array is returned when the pattern is obtained from the
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  # IO. The first element of the array is the entire string obtained from the
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  # IO until the pattern matches, followed by elements indicating which the
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  # pattern which matched to the anchor in the regular expression.
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  #
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  # The optional timeout parameter defines, in seconds, the total time to wait
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  # for the pattern.  If the timeout expires or eof is found, nil is returned
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  # or yielded.  However, the buffer in a timeout session is kept for the next
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  # expect call.  The default timeout is 9999999 seconds.
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  def expect(pat,timeout=9999999)
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    buf = ''.dup
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    case pat
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    when String
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      e_pat = Regexp.new(Regexp.quote(pat))
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    when Regexp
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      e_pat = pat
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    else
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      raise TypeError, "unsupported pattern class: #{pat.class}"
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    end
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    @unusedBuf ||= ''
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    while true
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      if not @unusedBuf.empty?
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        c = @unusedBuf.slice!(0)
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      elsif !IO.select([self],nil,nil,timeout) or eof? then
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        result = nil
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        @unusedBuf = buf
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        break
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      else
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        c = getc
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      end
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      buf << c
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      if $expect_verbose
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        STDOUT.print c
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        STDOUT.flush
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      end
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      if mat=e_pat.match(buf) then
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        result = [buf,*mat.captures]
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        break
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      end
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    end
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    if block_given? then
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      yield result
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    else
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      return result
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    end
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    nil
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  end
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end
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