+#include "note-collision.hh"
+#include "axis-group-interface.hh"
+#include "item.hh"
+
+class Collision_engraver : public Engraver
+{
+ Item *col_;
+ vector<Grob*> note_columns_;
+
+protected:
+ DECLARE_ACKNOWLEDGER (note_column);
+ void process_acknowledged ();
+ void stop_translation_timestep ();
+public:
+ TRANSLATOR_DECLARATIONS (Collision_engraver);
+};