refactor switch stmt
refactor switch stmt

go-distributed/meritop,dzch/taskgraph,dzch/taskgraph,BaiGang/taskgraph,kod3r/taskgraph,taskgraph/taskgraph,plutoshe/taskgraph,taskgraph/taskgraph,fengjingchao/taskgraph,kod3r/taskgraph,go-distributed/meritop,5kg/taskgraph,fengjingchao/taskgraph,plutoshe/mapreduceOfTaskgraph,BaiGang/taskgraph,5kg/taskgraph,plutoshe/mapreduceOfTaskgraph,plutoshe/taskgraph