/*
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
Dispatcher::Dispatcher ()
{
- self_scm_ = SCM_EOL;
listeners_ = SCM_EOL;
dispatchers_ = SCM_EOL;
listen_classes_ = SCM_EOL;
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);
+ Stream_event *ev = Stream_event::unsmob (sev);
SCM class_list = ev->get_property ("class");
if (!scm_is_pair (class_list))
{
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
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--)
assert (lists[0].prio > last_priority);
last_priority = lists[0].prio;
- Listener *l = unsmob_listener (scm_cdar (lists[0].list));
+ Listener *l = Listener::unsmob (scm_cdar (lists[0].list));
l->listen (ev->self_scm ());
#if 0
sent = true;
}
bool
-Dispatcher::is_listened (Stream_event *ev)
+Dispatcher::is_listened_class (SCM cl)
{
- for (SCM cl = ev->get_property ("class"); scm_is_pair (cl); cl = scm_cdr (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 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)
{
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
for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
{
int priority = scm_to_int (scm_cdar (disp));
- Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
+ Dispatcher *d = Dispatcher::unsmob (scm_caar (disp));
d->internal_add_listener (GET_LISTENER (dispatch), ev_class, priority);
}
listen_classes_ = scm_cons (ev_class, listen_classes_);
SCM dummy = scm_cons (SCM_EOL, list);
SCM e = dummy;
while (scm_is_pair (scm_cdr (e)))
- if (*unsmob_listener (scm_cdadr (e)) == l && first)
+ if (*Listener::unsmob (scm_cdadr (e)) == l && first)
{
scm_set_cdr_x (e, scm_cddr (e));
first = false;
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. */
for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
{
- Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
+ Dispatcher *d = Dispatcher::unsmob (scm_caar (disp));
d->remove_listener (GET_LISTENER (dispatch), ev_class);
}
listen_classes_ = scm_delq_x (ev_class, listen_classes_);
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;
}
projects / lilypond.git / blobdiff