optimize project structure

database/router.go

@@ -0,0 +1,28 @@
+package database
+
+import (
+	"strings"
+)
+
+var cmdTable = make(map[string]*command)
+
+type command struct {
+	executor ExecFunc
+	prepare  PreFunc // return related keys command
+	undo     UndoFunc
+	arity    int // allow number of args, arity < 0 means len(args) >= -arity
+	flags    int
+}
+
+// RegisterCommand registers a new command
+// arity means allowed number of cmdArgs, arity < 0 means len(args) >= -arity.
+// for example: the arity of `get` is 2, `mget` is -2
+func RegisterCommand(name string, executor ExecFunc, prepare PreFunc, rollback UndoFunc, arity int) {
+	name = strings.ToLower(name)
+	cmdTable[name] = &command{
+		executor: executor,
+		prepare:  prepare,
+		undo:     rollback,
+		arity:    arity,
+	}
+}