Go设计模式之备忘录模式讲解和代码示例

package main
type Originator struct {
	state string
}
// 创建快照
func (e *Originator) createMemento() *Memento {
	return &Memento{state: e.state}
}
// 回复快照
func (e *Originator) restoreMemento(m *Memento) {
	e.state = m.getSavedState()
}
func (e *Originator) setState(state string) {
	e.state = state
}
func (e *Originator) getState() string {
	return e.state
}

package main
type Memento struct {
	state string
}
func (m *Memento) getSavedState() string {
	return m.state
}

package main
type Caretaker struct {
	mementoArray []*Memento
}
func (c *Caretaker) addMemento(m *Memento) {
	c.mementoArray = append(c.mementoArray, m)
}
func (c *Caretaker) getMemento(index int) *Memento {
	return c.mementoArray[index]
}

package main
import "fmt"
func main() {
	caretaker := &Caretaker{
		mementoArray: make([]*Memento, 0),
	}
	originator := &Originator{
		state: "A",
	}
	fmt.Printf("Originator Current State: %s\n", originator.getState())
	// 添加一个备忘录
	caretaker.addMemento(originator.createMemento())
	originator.setState("C")
	fmt.Printf("Originator Current State: %s\n", originator.getState())
	caretaker.addMemento(originator.createMemento())
	originator.restoreMemento(caretaker.getMemento(1))
	fmt.Printf("Restored to State: %s\n", originator.getState())
	originator.restoreMemento(caretaker.getMemento(0))
	fmt.Printf("Restored to State: %s\n", originator.getState())
}