add a new API to set auto complete

operation.go

@@ -405,6 +405,10 @@ func (op *Operation) SetConfig(cfg *Config) (*Config, error) {
 	// so if we use it next time, we need to reopen it by `InitHistory()`
 	op.history.Init()
 
+	if op.cfg.AutoComplete != nil {
+		op.opCompleter = newOpCompleter(op.buf.w, op)
+	}
+
 	op.opSearch = cfg.opSearch
 	return old, nil
 }

std.go

@@ -33,6 +33,13 @@ func SetHistoryPath(fp string) {
 	ins.SetConfig(cfg)
 }
 
+func SetAutoComplete(completer AutoCompleter) {
+	ins := getInstance()
+	cfg := ins.Config.Clone()
+	cfg.AutoComplete = completer
+	ins.SetConfig(cfg)
+}
+
 func AddHistory(content string) error {
 	ins := getInstance()
 	return ins.SaveHistory(content)