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cancelevent.go
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/
cancelevent.go
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// Copyright 2011 The Walk Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build windows
package walk
type cancelEventHandlerInfo struct {
handler CancelEventHandler
once bool
}
type CancelEventHandler func(canceled *bool)
type CancelEvent struct {
handlers []cancelEventHandlerInfo
}
func (e *CancelEvent) Attach(handler CancelEventHandler) int {
handlerInfo := cancelEventHandlerInfo{handler, false}
for i, h := range e.handlers {
if h.handler == nil {
e.handlers[i] = handlerInfo
return i
}
}
e.handlers = append(e.handlers, handlerInfo)
return len(e.handlers) - 1
}
func (e *CancelEvent) Detach(handle int) {
e.handlers[handle].handler = nil
}
func (e *CancelEvent) Once(handler CancelEventHandler) {
i := e.Attach(handler)
e.handlers[i].once = true
}
type CancelEventPublisher struct {
event CancelEvent
}
func (p *CancelEventPublisher) Event() *CancelEvent {
return &p.event
}
func (p *CancelEventPublisher) Publish(canceled *bool) {
for i, h := range p.event.handlers {
if h.handler != nil {
h.handler(canceled)
if h.once {
p.event.Detach(i)
}
}
}
}