# Usage:
#	require "open3"
#
#	in, out, err = Open3.popen3('nroff -man')
#  or
#	include Open3
#	in, out, err = popen3('nroff -man')
#

module Open3
  #[stdin, stdout, stderr] = popen3(command);
  def popen3(cmd)
    pw = IO::pipe   # pipe[0] for read, pipe[1] for write
    pr = IO::pipe
    pe = IO::pipe

    pid = fork{
      # child
      pw[1].close
      STDIN.reopen(pw[0])
      pw[0].close

      pr[0].close
      STDOUT.reopen(pr[1])
      pr[1].close

      pe[0].close
      STDERR.reopen(pe[1])
      pe[1].close

      exec(cmd)
      _exit 127
    }

    pw[0].close
    pr[1].close
    pe[1].close
    Thread.start do
      sleep 1
      Process.waitpid(pid)
    end
    pi = [ pw[1], pr[0], pe[0] ]
    if defined? yield
      return yield *pi
    end
    pi
  end
  module_function :popen3
end

if $0 == __FILE__
  a = Open3.popen3("nroff -man")
  Thread.start do
    while line = gets
      a[0].print line
    end
    a[0].close
  end
  while line = a[1].gets
    print ":", line
  end
end