文章目录
十九、memento 备忘录模式
保存状态快照，随时恢复指定版本
19.1 text_memento
├── originator.go
├── snapshot.go
├── snapshot_manager.go
└── snapshot_manager_test.go
19.1.1 snapshot_manager_test.go
package _91text_memento
import (
"github.com/stretchr/testify/require"
"testing"
)
/*
=== RUN TestSnapshotManager
--- PASS: TestSnapshotManager (0.00s)
PASS
*/
func TestSnapshotManager(t *testing.T) {
const state0 = "状态0"
m := &snapshotManager{}
o := &originator{state: state0}
m.addSnapshot(o.saveToSnapshot())
s0 := m.getSnapshot(0)
require.EqualValues(t, s0.getSavedState(), state0)
const state1 = "状态1"
o.setState(state1)
m.addSnapshot(o.saveToSnapshot())
s0 = m.getSnapshot(0)
require.EqualValues(t, s0.getSavedState(), state0)
s1 := m.getSnapshot(1)
require.EqualValues(t, s1.getSavedState(), state1)
}
19.1.2 snapshot_manager.go
package _91text_memento
type snapshotManager struct {
snapshots []snapshot
}
func (m *snapshotManager) addSnapshot(s snapshot) {
m.snapshots = append(m.snapshots, s)
}
func (m *snapshotManager) getSnapshot(index int) snapshot {
return m.snapshots[index]
}
19.1.3 snapshot.go
package _91text_memento
type snapshot struct {
state string
}
func (s *snapshot) getSavedState() string {
return s.state
}
19.1.4 originator.go
package _91text_memento
type originator struct {
state string
}
func (o *originator) saveToSnapshot() snapshot {
return snapshot{state: o.state}
}
func (o *originator) loadFromSnapshot(s snapshot) {
o.state = s.getSavedState()
}
func (o *originator) setState(state string) {
o.state = state
}