fiber练习，模拟管道功能

fiber_exam.rb

class PipeElement
  attr_accessor :source

  def initialize
    @delegator = Fiber.new do
      process
    end
  end

  def | other
    other.source = self
    other
  end

  def process
    while v = receive
      handle v
    end
  end

  def handle v
    send v
  end

  def send v
    puts "----------------#{self.class}: send"
    Fiber.yield v
  end

  def receive
    source.resume
  end

  def resume
    puts "----------------#{self.class}: resume"
    @delegator.resume
  end
end

class Producer < PipeElement
  def receive
    gets
  end
end

class Filter < PipeElement
  def initialize
    super
    @line = 1
  end

  def handle v
    send "#{@line}: #{v}"
    @line += 1
  end
end

class Stop < PipeElement
  def receive
    v = source.resume
    return nil if v.chomp.include?('stop')
    v
  end
end

class Consumer < PipeElement
  def handle v
    puts v
  end
end

x = Producer.new
y = Filter.new
z = Consumer.new
a = Stop.new

t = x | a | y | z
t.resume