classes derived from Smob<...>.
*/
+#include "callback.hh"
#include "smobs.hh"
-#include "stream-event.hh"
// A listener is essentially any procedure accepting a single argument
// (namely an event). The class Listener (or rather a smobbed_copy of
return SCM_UNSPECIFIED;
}
- SCM mark_smob ()
+ SCM mark_smob () const
{
scm_gc_mark (callback_);
return target_;
return *unchecked_unsmob (a) == *unchecked_unsmob (b)
? SCM_BOOL_T : SCM_BOOL_F;
}
-};
-// A callback wrapper creates a Scheme-callable version of a
-// non-static class member function callback which you can call with a
-// class instance and an event.
-//
-// If you have a class member function
-// void T::my_listen (SCM ev)
-// then Callback_wrapper::make_smob<T, SCM, &T::my_listen> ()
-// will return an SCM function roughly defined as
-// (lambda (target ev) (target->my_listen ev))
-//
-// The setup is slightly tricky since the make_smob quasi-constructor
-// call is a template function templated on the given callback, and so
-// is the trampoline it uses for redirecting the callback. The class
-// itself, however, is not templated as that would create a wagonload
-// of SCM types.
-
-class Callback_wrapper : public Simple_smob<Callback_wrapper>
-{
- // We use an ordinary function pointer pointing to a trampoline
- // function (templated on the callback in question) instead of
- // storing a member function pointer to a common base class like
- // Smob_core. The additional code for the trampolines is negligible
- // and the performance implications of using member function
- // pointers in connection with inheritance are somewhat opaque as
- // this involves an adjustment of the this pointer from Smob_core to
- // the scope containing the callback.
- void (*trampoline_) (SCM, SCM);
template <class T, void (T::*callback)(SCM)>
- static void trampoline (SCM target, SCM ev)
+ static SCM trampoline (SCM target, SCM ev)
{
T *t = unsmob<T> (target);
LY_ASSERT_SMOB (T, target, 1);
(t->*callback) (ev);
- }
- template <class T, void (T::*callback)(Stream_event *)>
- static void trampoline (SCM target, SCM event)
- {
- // The same, but for callbacks for translator listeners which get
- // the unpacked event which, in turn, gets protected previously
-
- T *t = unsmob<T> (target);
- LY_ASSERT_SMOB (T, target, 1);
- LY_ASSERT_SMOB (Stream_event, event, 2);
-
- t->protect_event (event);
- (t->*callback) (unsmob<Stream_event> (event));
- }
-
- Callback_wrapper (void (*trampoline) (SCM, SCM)) : trampoline_ (trampoline)
- { } // Private constructor, use only in make_smob
-public:
- LY_DECLARE_SMOB_PROC (&Callback_wrapper::call, 2, 0, 0)
- SCM call (SCM target, SCM ev)
- {
- trampoline_ (target, ev);
- return SCM_UNSPECIFIED;
- }
- // Callback wrappers are for an unchanging entity, so we do the Lisp
- // creation just once on the first call of make_smob. So we only
- // get a single Callback_wrapper instance for each differently
- // templated make_smob call.
- template <class T, class Arg, void (T::*callback)(Arg)>
- static SCM make_smob ()
- {
- static SCM res = scm_permanent_object
- (Callback_wrapper (trampoline<T, callback>).smobbed_copy ());
- return res;
+ return SCM_UNDEFINED;
}
};
-#define GET_LISTENER(cl, proc) get_listener (Callback_wrapper::make_smob<cl, SCM, &cl::proc> ())
+#define GET_LISTENER(cl, proc) get_listener (Callback_wrapper::make_smob<Listener::trampoline<cl, &cl::proc> > ())
#endif /* LISTENER_HH */