X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fdispatcher.cc;h=915e1eff0aa2db05e40b77499dafeaad2d5737b8;hb=9e781b7dc83b60a543ce218aa1a5f139f74c760f;hp=ad1a624b121917b67fe03bc0944cce96a0325de4;hpb=2944a83e59f487894a214769392ce27289accb71;p=lilypond.git

diff --git a/lily/dispatcher.cc b/lily/dispatcher.cc
index ad1a624b12..915e1eff0a 100644
--- a/lily/dispatcher.cc
+++ b/lily/dispatcher.cc
@@ -1,7 +1,7 @@
 /*
   This file is part of LilyPond, the GNU music typesetter.
 
-  Copyright (C) 2005--2012 Erik Sandberg  <mandolaerik@gmail.com>
+  Copyright (C) 2005--2014 Erik Sandberg  <mandolaerik@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -59,7 +59,7 @@ Dispatcher::print_smob (SCM s, SCM p, scm_print_state *)
   Dispatcher *me = (Dispatcher *) SCM_CELL_WORD_1 (s);
   scm_puts ("#<Dispatcher ", p);
   scm_write (scm_call_1 (ly_lily_module_constant ("hash-table->alist"),
-			 me->listeners_), p);
+                         me->listeners_), p);
   scm_puts (">", p);
   return 1;
 }
@@ -71,25 +71,25 @@ Event dispatching:
   This is done by keeping a priority queue of listener lists,
   and iteratively send the event to the lowest-priority listener.
 - An event is never sent twice to listeners with equal priority.
+  The only case where listeners with equal priority may exist is when
+  two dispatchers are connected for more than one event type.  In that
+  case, the respective listeners all have the same priority, making
+  sure that any event is only dispatched at most once for that
+  combination of dispatchers, even if it matches more than one event
+  type.
 */
 IMPLEMENT_LISTENER (Dispatcher, dispatch);
 void
 Dispatcher::dispatch (SCM sev)
 {
   Stream_event *ev = unsmob_stream_event (sev);
-  SCM class_symbol = ev->get_property ("class");
-  if (!scm_is_symbol (class_symbol))
-    {
-      warning (_ ("Event class should be a symbol"));
-      return;
-    }
-
-  SCM class_list = scm_call_1 (ly_lily_module_constant ("ly:make-event-class"), class_symbol);
+  SCM class_list = ev->get_property ("class");
   if (!scm_is_pair (class_list))
     {
-      ev->origin ()->warning (_f ("Unknown event class %s", ly_symbol2string (class_symbol).c_str ()));
+      ev->origin ()->warning (_ ("Event class should be a list"));
       return;
     }
+
 #if 0
   bool sent = false;
 #endif
@@ -102,7 +102,7 @@ Dispatcher::dispatch (SCM sev)
     listener list, and the lowest priority element is repeatedly
     extracted and called.
 
-    The priority queue is implemented as a bubble-sorted C
+    The priority queue is implemented as an insertion-sorted C
     array. Using the stack instead of native Scheme datastructures
     avoids overheads for memory allocation. The queue is usually small
     (around 2 elements), so the quadratic sorting time is not a
@@ -121,7 +121,7 @@ Dispatcher::dispatch (SCM sev)
         num_classes--;
       else
         {
-          // bubblesort.
+          // insertion sort.
           int prio = scm_to_int (scm_caar (list));
           int j;
           for (j = i; j > 0 && lists[j - 1].prio > prio; j--)
@@ -173,12 +173,43 @@ Dispatcher::dispatch (SCM sev)
 #endif
 }
 
+bool
+Dispatcher::is_listened_class (SCM cl)
+{
+  for (; scm_is_pair (cl); cl = scm_cdr (cl))
+    {
+      SCM list = scm_hashq_ref (listeners_, scm_car (cl), SCM_EOL);
+      if (scm_is_pair (list))
+        return true;
+    }
+  return false;
+}
+
+static SCM
+accumulate_types (void * /* closure */,
+                  SCM key,
+                  SCM val,
+                  SCM result)
+{
+  if (scm_is_pair (val))
+    return scm_cons (key, result);
+  return result;
+}
+
+SCM
+Dispatcher::listened_types ()
+{
+  return scm_internal_hash_fold ((scm_t_hash_fold_fn) &accumulate_types,
+                                 NULL, SCM_EOL, listeners_);
+}
+
 void
 Dispatcher::broadcast (Stream_event *ev)
 {
   dispatch (ev->self_scm ());
 }
 
+// add_listener will always assign a new priority for each call
 void
 Dispatcher::add_listener (Listener l, SCM ev_class)
 {
@@ -189,6 +220,14 @@ inline void
 Dispatcher::internal_add_listener (Listener l, SCM ev_class, int priority)
 {
   SCM list = scm_hashq_ref (listeners_, ev_class, SCM_EOL);
+  // if ev_class is not yet listened to, we go through our list of
+  // source dispatchers and register ourselves there with the priority
+  // we have reserved for this dispatcher.  The priority system
+  // usually distributes events in the order events are registered.
+  // The reuse of a previous priority when registering another event
+  // for a dispatcher/dispatcher connection bypasses the normal
+  // ordering, but it is the mechanism by which duplicate broadcasts
+  // of the same event from one dispatcher to another are avoided.
   if (!scm_is_pair (list))
     {
       /* Tell all dispatchers that we listen to, that we want to hear ev_class
@@ -235,7 +274,7 @@ Dispatcher::remove_listener (Listener l, SCM ev_class)
   scm_hashq_set_x (listeners_, ev_class, list);
 
   if (first)
-    warning ("Attempting to remove nonexisting listener.");
+    warning (_ ("Attempting to remove nonexisting listener."));
   else if (!scm_is_pair (list))
     {
       /* Unregister with all dispatchers. */
@@ -252,12 +291,16 @@ Dispatcher::remove_listener (Listener l, SCM ev_class)
 void
 Dispatcher::register_as_listener (Dispatcher *disp)
 {
+  // We are creating and remembering the priority _we_ have with the
+  // foreign dispatcher.  All events are dispatched with the same
+  // priority.  The result is that, for example, a single event class
+  // will only trigger an event listener once.
   int priority = ++disp->priority_count_;
 
   // Don't register twice to the same dispatcher.
   if (scm_assq (disp->self_scm (), dispatchers_) != SCM_BOOL_F)
     {
-      warning ("Already listening to dispatcher, ignoring request");
+      warning (_ ("Already listening to dispatcher, ignoring request"));
       return;
     }