Add generic event

bot/event.go

@@ -5,7 +5,8 @@ import (
 )
 
 type Events struct {
-	handlers map[int32]*handlerHeap
+	generic  *handlerHeap           // for every packet
+	handlers map[int32]*handlerHeap // for specific packet id only
 }
 
 func (e *Events) AddListener(listeners ...PacketHandler) {
@@ -21,6 +22,18 @@ func (e *Events) AddListener(listeners ...PacketHandler) {
 	}
 }
 
+// AddGeneric adds listeners like AddListener, but the packet ID is ignored.
+// Generic listener is always called before specific packet listener.
+func (e *Events) AddGeneric(listeners ...PacketHandler) {
+	for _, l := range listeners {
+		if e.generic == nil {
+			e.generic = &handlerHeap{l}
+		} else {
+			e.generic.Push(l)
+		}
+	}
+}
+
 type PacketHandlerFunc func(p pk.Packet) error
 type PacketHandler struct {
 	ID       int32