uUI - OnSelect: From Mouse/Pointer or Keyboard/Controller?

I am using ISelectHandler and IPointerClickHandler. Now when a UI Object is clicked, it is also automatically selected first. I want to find out if that selection was triggered by a pointer click, or by a keyboard/controller event.

Since OnSelect only has access to the BaseEventData I have no idea how to do this. My first idea was to use the input module involved, but since I'm using the Standalone module, both mouseclick and keyboard/controller event come from the same module, so I can't use that to differentiate.

 void OnSelect(BaseEventData eventData) {
     if ( !Input.GetMouseButton(0) ) {
         Do something for mouse;
     }
     else {
         Do something different for keyboard/controller;
     }
 }

Any ideas?

Update: I've found a solution by asking the Input Module if the mouse was pressed, but this seems somehwat hacky, and won't work for touch inputs.