package clientv3
import (
pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
)
type CompareTarget int
type CompareResult int
const (
CompareVersion CompareTarget = iota
CompareCreated CompareModified CompareValue)
type Cmp pb.Compare
func Compare(cmp Cmp, result string, v interface{}) Cmp {
var r pb.Compare_CompareResult
switch result {
case "=":
r = pb.Compare_EQUAL
case "!=":
r = pb.Compare_NOT_EQUAL
case ">":
r = pb.Compare_GREATER
case "<":
r = pb.Compare_LESS
default:
panic("Unknown result op")
}cmp.Result = r
switch cmp.Target {
case pb.Compare_VALUE:
val, ok := v.(string)
if !ok {
panic("bad compare value")
}cmp.TargetUnion = &pb.Compare_Value{Value: []byte(val)}
case pb.Compare_VERSION:
cmp.TargetUnion = &pb.Compare_Version{Version: mustInt64(v)}
case pb.Compare_CREATE:
cmp.TargetUnion = &pb.Compare_CreateRevision{CreateRevision: mustInt64(v)}
case pb.Compare_MOD:
cmp.TargetUnion = &pb.Compare_ModRevision{ModRevision: mustInt64(v)}
default:
panic("Unknown compare type")
}return cmp
}
func Value(key string) Cmp {
return Cmp{Key: []byte(key), Target: pb.Compare_VALUE}
}
func Version(key string) Cmp {
return Cmp{Key: []byte(key), Target: pb.Compare_VERSION}
}
func CreateRevision(key string) Cmp {
return Cmp{Key: []byte(key), Target: pb.Compare_CREATE}
}
func ModRevision(key string) Cmp {
return Cmp{Key: []byte(key), Target: pb.Compare_MOD}
}
func mustInt64(val interface{}) int64 {
if v, ok := val.(int64); ok {
return v
}if v, ok := val.(int); ok {
return int64(v)
}panic("bad value")
}
原文：http://www.cnblogs.com/zhangboyu/p/7452671.html