72 lines
1.4 KiB
Go
72 lines
1.4 KiB
Go
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package observer
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import "reflect"
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// Subject 被观察者
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type Subject struct {
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observers []Observer
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in chan any
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}
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// Observer 观察者 chan
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type Observer chan any
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// NewSubject 获取被观察者实例
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func NewSubject() Subject {
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return Subject{in: make(chan any)}
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}
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// Attach 观察者绑定
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func (s *Subject) Attach(observer ...Observer) {
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s.observers = append(s.observers, observer...)
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}
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// Detach 观察者解绑
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func (s *Subject) Detach(observer Observer) {
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for i, obs := range s.observers {
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if obs == observer {
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s.observers = append(s.observers[:i], s.observers[i+1:]...)
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close(observer)
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break
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}
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}
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}
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// Notify 通知观察者
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func (s *Subject) Notify(data any) {
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go s.fanOut(s.in, s.observers)
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s.in <- data
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}
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// fanOut 扇出模式实现
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func (s *Subject) fanOut(ch <-chan interface{}, out []Observer) {
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var cases []reflect.SelectCase
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// 添加输入 chan 的 reflect.SelectCase
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cases = append(cases, reflect.SelectCase{
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Dir: reflect.SelectRecv,
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Chan: reflect.ValueOf(ch),
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})
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go func() {
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defer func() {
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// 退出时关闭所有的输出 chan
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for _, o := range out {
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close(o)
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}
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}()
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for {
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_, value, ok := reflect.Select(cases) // 从输入 chan 中读取数据
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if !ok {
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// 输入 channel 被关闭
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return
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}
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// 输入 channel 接收到数据
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for _, o := range out {
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o <- value.Interface() // 放入到输出 chan 中，同步方式
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}
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}
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}()
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}
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