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/*
* Copyright (C) 2017 ~ 2018 Deepin Technology Co., Ltd.
*
* Author: jouyouyun <jouyouwen717@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// fork from https://github.com/pocke/goevent
package event
import (
"errors"
"fmt"
"reflect"
"sync"
)
type Event struct {
listeners []reflect.Value
lmu sync.RWMutex
argTypes []reflect.Type
}
// New
func New(f interface{}) *Event {
fn := reflect.ValueOf(f)
if fn.Kind() != reflect.Func {
panic("not a function")
}
fnType := fn.Type()
fnNum := fnType.NumIn()
argTypes := make([]reflect.Type, fnNum)
for i := 0; i < fnNum; i++ {
argTypes[i] = fnType.In(i)
}
return &Event{
argTypes: argTypes,
}
}
// On
func (e *Event) On(f interface{}) error {
fn, err := e.checkFuncSignature(f)
if err != nil {
return err
}
e.lmu.Lock()
e.listeners = append(e.listeners, *fn)
e.lmu.Unlock()
return nil
}
// Off
func (e *Event) Off(f interface{}) error {
fn := reflect.ValueOf(f)
e.lmu.Lock()
l := len(e.listeners)
m := l // for error check
for i := 0; i < l; i++ {
if fn == e.listeners[i] {
// XXX: GC Ref: http://jxck.hatenablog.com/entry/golang-slice-internals
e.listeners = append(e.listeners[:i], e.listeners[i+1:]...)
l--
i--
}
}
e.lmu.Unlock()
if l == m {
return fmt.Errorf("Listener does't exists")
}
return nil
}
// Trigger
func (e *Event) Trigger(args ...interface{}) error {
// check args len
if len(e.argTypes) != len(args) {
return fmt.Errorf("argument length expected %d, but got %d", len(e.argTypes), len(args))
}
// check each arg type
for i, t := range e.argTypes {
t0 := reflect.TypeOf(args[i])
if t != t0 {
return fmt.Errorf("args[%d] type expected %s, but got %s", i, t, t0)
}
}
arguments := make([]reflect.Value, len(args))
for i, v := range args {
arguments[i] = reflect.ValueOf(v)
}
e.lmu.RLock()
defer e.lmu.RUnlock()
wg := sync.WaitGroup{}
wg.Add(len(e.listeners))
for _, fn := range e.listeners {
go func(f reflect.Value) {
defer wg.Done()
f.Call(arguments)
}(fn)
}
wg.Wait()
return nil
}
func (e *Event) checkFuncSignature(f interface{}) (*reflect.Value, error) {
fn := reflect.ValueOf(f)
if fn.Kind() != reflect.Func {
return nil, errors.New("not a function")
}
fnType := fn.Type()
fnNum := fnType.NumIn()
// check args len
if len(e.argTypes) != fnNum {
return nil, fmt.Errorf("argument length expected %d, but got %d", len(e.argTypes), fnNum)
}
// check each arg type
for i, t := range e.argTypes {
t0 := fnType.In(i)
if t != t0 {
return nil, fmt.Errorf("args[%d] type expected %s, but got %s", i, t, t0)
}
}
return &fn, nil
}
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