Golang EventEmitter

event_emitter.go

package main

import "fmt"

type EventFunc = func(i interface{})

type Event struct {
	Funcs       []EventFunc
	Once        bool
	CallCounter int
}

type EventEmitter struct {
	Events map[string]Event
}

func (e *EventEmitter) AddEventListener(eventName string, event EventFunc, once bool) {
	found := false
	if e.Events == nil {
		e.Events = make(map[string]Event)
	}

	for name, _ := range e.Events {
		if name == eventName {
			found = true

			//evt.Funcs = append(evt.Funcs, event)
			if entry, ok := e.Events[name]; ok {
				entry.Funcs = append(entry.Funcs, event)
				e.Events[name] = entry
			}

		}
	}

	if !found {
		e.Events[eventName] = Event{
			Funcs:       []EventFunc{event},
			Once:        once,
			CallCounter: 0,
		}
	}
}

func (e EventEmitter) GetCallCount(eventName string) int {

	for name, _ := range e.Events {
		if name == eventName {
			return e.Events[name].CallCounter
		}
	}

	return 0
}

func (e *EventEmitter) On(eventName string, event EventFunc) {
	e.AddEventListener(eventName, event, false)
}

func (e *EventEmitter) Once(eventName string, event EventFunc) {
	e.AddEventListener(eventName, event, true)

}

func (e *EventEmitter) RemoveEventListener(eventName string) {
	for name, _ := range e.Events {
		if name == eventName {
			delete(e.Events, name)
		}
	}
}

func (e *EventEmitter) Emit(eventName string, data interface{}) {
	for name, event := range e.Events {
		if name == eventName {
			for _, fn := range event.Funcs {
				fn(data)
				if entry, ok := e.Events[name]; ok {
					entry.CallCounter = entry.CallCounter + 1
					e.Events[name] = entry
				}

			}

			if event.Once {
				delete(e.Events, eventName)
			}
			return
		}
	}
	fmt.Printf("Event %s not found\n", eventName)
}

func main() {
	emitter := EventEmitter{}
	emitter.On("click", func(i interface{}) {
		fmt.Print("Click1 -->")
		fmt.Println(i)
	})

	emitter.On("click", func(i interface{}) {
		fmt.Print("Click2 -->")
		fmt.Println(i)
	})

	emitter.Emit("click", 1212)

	fmt.Println(emitter.GetCallCount("click"))

	emitter.RemoveEventListener("click")
	emitter.Emit("click", "asddf")
}