2 This file is part of LilyPond, the GNU music typesetter.
4 Copyright (C) 2005--2012 Erik Sandberg <mandolaerik@gmail.com>
6 LilyPond is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 LilyPond is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with LilyPond. If not, see <http://www.gnu.org/licenses/>.
20 #include "dispatcher.hh"
22 #include "international.hh"
23 #include "ly-smobs.icc"
26 IMPLEMENT_SMOBS (Dispatcher);
27 IMPLEMENT_TYPE_P (Dispatcher, "ly:dispatcher?");
28 IMPLEMENT_DEFAULT_EQUAL_P (Dispatcher);
30 Dispatcher::~Dispatcher ()
34 Dispatcher::Dispatcher ()
38 dispatchers_ = SCM_EOL;
39 listen_classes_ = SCM_EOL;
41 // TODO: use resizable hash (guile 1.8)
42 // listeners_ = scm_c_make_hash_table (0);
43 listeners_ = scm_c_make_hash_table (17);
48 Dispatcher::mark_smob (SCM sm)
50 Dispatcher *me = (Dispatcher *) SCM_CELL_WORD_1 (sm);
51 scm_gc_mark (me->dispatchers_);
52 scm_gc_mark (me->listen_classes_);
53 return me->listeners_;
57 Dispatcher::print_smob (SCM s, SCM p, scm_print_state *)
59 Dispatcher *me = (Dispatcher *) SCM_CELL_WORD_1 (s);
60 scm_puts ("#<Dispatcher ", p);
61 scm_write (scm_call_1 (ly_lily_module_constant ("hash-table->alist"),
69 - Collect a list of listeners for each relevant class
70 - Send the event to each of these listeners, in increasing priority order.
71 This is done by keeping a priority queue of listener lists,
72 and iteratively send the event to the lowest-priority listener.
73 - An event is never sent twice to listeners with equal priority.
75 IMPLEMENT_LISTENER (Dispatcher, dispatch);
77 Dispatcher::dispatch (SCM sev)
79 Stream_event *ev = unsmob_stream_event (sev);
80 SCM class_list = ev->get_property ("class");
81 if (!scm_is_pair (class_list))
83 ev->origin ()->warning (_ ("Event class should be a list"));
90 int num_classes = scm_ilength (class_list);
93 For each event class there is a list of listeners, which is
94 ordered by priority. Our next task is to call these listeners, in
95 priority order. A priority queue stores the next element in each
96 listener list, and the lowest priority element is repeatedly
99 The priority queue is implemented as a bubble-sorted C
100 array. Using the stack instead of native Scheme datastructures
101 avoids overheads for memory allocation. The queue is usually small
102 (around 2 elements), so the quadratic sorting time is not a
103 problem. (if this changes, it's easy to rewrite this routine using
106 The first step is to collect all listener lists and to initially
107 insert them in the priority queue.
109 struct { int prio; SCM list; } lists[num_classes + 1];
111 for (SCM cl = class_list; scm_is_pair (cl); cl = scm_cdr (cl))
113 SCM list = scm_hashq_ref (listeners_, scm_car (cl), SCM_EOL);
114 if (!scm_is_pair (list))
119 int prio = scm_to_int (scm_caar (list));
121 for (j = i; j > 0 && lists[j - 1].prio > prio; j--)
122 lists[j] = lists[j - 1];
123 lists[j].prio = prio;
124 lists[j].list = list;
128 lists[num_classes].prio = INT_MAX;
130 // Never send an event to two listeners with equal priority.
131 int last_priority = -1;
133 Each iteration extracts the lowest-priority element, which is a
134 list of listeners. The first listener is called, and the tail of
135 the list is pushed back into the priority queue.
139 // Send the event, if we haven't already sent it to this target.
140 if (lists[0].prio != last_priority)
142 // process the listener
143 assert (lists[0].prio > last_priority);
144 last_priority = lists[0].prio;
146 Listener *l = unsmob_listener (scm_cdar (lists[0].list));
147 l->listen (ev->self_scm ());
152 // go to the next listener; bubble-sort the class list.
153 SCM next = scm_cdr (lists[0].list);
154 if (!scm_is_pair (next))
156 int prio = (scm_is_pair (next)) ? scm_to_int (scm_caar (next)) : INT_MAX;
157 for (i = 0; prio > lists[i + 1].prio; i++)
158 lists[i] = lists[i + 1];
159 lists[i].prio = prio;
160 lists[i].list = next;
164 /* TODO: Uncomment. */
166 warning (_f ("Junking event: %s", ly_symbol2string (class_symbol).c_str ()));
171 Dispatcher::is_listened_class (SCM cl)
173 for (; scm_is_pair (cl); cl = scm_cdr (cl))
175 SCM list = scm_hashq_ref (listeners_, scm_car (cl), SCM_EOL);
176 if (scm_is_pair (list))
183 accumulate_types (void * /* closure */,
188 if (scm_is_pair (val))
189 return scm_cons (key, result);
194 Dispatcher::listened_types ()
196 return scm_internal_hash_fold ((scm_t_hash_fold_fn) &accumulate_types,
197 NULL, SCM_EOL, listeners_);
201 Dispatcher::broadcast (Stream_event *ev)
203 dispatch (ev->self_scm ());
207 Dispatcher::add_listener (Listener l, SCM ev_class)
209 internal_add_listener (l, ev_class, ++priority_count_);
213 Dispatcher::internal_add_listener (Listener l, SCM ev_class, int priority)
215 SCM list = scm_hashq_ref (listeners_, ev_class, SCM_EOL);
216 if (!scm_is_pair (list))
218 /* Tell all dispatchers that we listen to, that we want to hear ev_class
220 for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
222 int priority = scm_to_int (scm_cdar (disp));
223 Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
224 d->internal_add_listener (GET_LISTENER (dispatch), ev_class, priority);
226 listen_classes_ = scm_cons (ev_class, listen_classes_);
228 SCM entry = scm_cons (scm_from_int (priority), l.smobbed_copy ());
229 list = scm_merge (list, scm_list_1 (entry), ly_lily_module_constant ("car<"));
230 scm_hashq_set_x (listeners_, ev_class, list);
234 Dispatcher::remove_listener (Listener l, SCM ev_class)
236 SCM list = scm_hashq_ref (listeners_, ev_class, SCM_EOL);
240 programming_error ("remove_listener called with incorrect class.");
244 // We just remove the listener once.
247 SCM dummy = scm_cons (SCM_EOL, list);
249 while (scm_is_pair (scm_cdr (e)))
250 if (*unsmob_listener (scm_cdadr (e)) == l && first)
252 scm_set_cdr_x (e, scm_cddr (e));
258 list = scm_cdr (dummy);
259 scm_hashq_set_x (listeners_, ev_class, list);
262 warning (_ ("Attempting to remove nonexisting listener."));
263 else if (!scm_is_pair (list))
265 /* Unregister with all dispatchers. */
266 for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
268 Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
269 d->remove_listener (GET_LISTENER (dispatch), ev_class);
271 listen_classes_ = scm_delq_x (ev_class, listen_classes_);
275 /* Register as a listener to another dispatcher. */
277 Dispatcher::register_as_listener (Dispatcher *disp)
279 int priority = ++disp->priority_count_;
281 // Don't register twice to the same dispatcher.
282 if (scm_assq (disp->self_scm (), dispatchers_) != SCM_BOOL_F)
284 warning (_ ("Already listening to dispatcher, ignoring request"));
288 dispatchers_ = scm_acons (disp->self_scm (), scm_from_int (priority), dispatchers_);
290 Listener list = GET_LISTENER (dispatch);
291 for (SCM cl = listen_classes_; scm_is_pair (cl); cl = scm_cdr (cl))
293 disp->internal_add_listener (list, scm_car (cl), priority);
297 /* Unregister as a listener to another dispatcher. */
299 Dispatcher::unregister_as_listener (Dispatcher *disp)
301 dispatchers_ = scm_assq_remove_x (dispatchers_, disp->self_scm ());
303 Listener listener = GET_LISTENER (dispatch);
304 for (SCM cl = listen_classes_; scm_is_pair (cl); cl = scm_cdr (cl))
306 disp->remove_listener (listener, scm_car (cl));