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 (Stream_event *ev)
173 for (SCM cl = ev->get_property ("class"); 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))
184 Dispatcher::broadcast (Stream_event *ev)
186 dispatch (ev->self_scm ());
190 Dispatcher::add_listener (Listener l, SCM ev_class)
192 internal_add_listener (l, ev_class, ++priority_count_);
196 Dispatcher::internal_add_listener (Listener l, SCM ev_class, int priority)
198 SCM list = scm_hashq_ref (listeners_, ev_class, SCM_EOL);
199 if (!scm_is_pair (list))
201 /* Tell all dispatchers that we listen to, that we want to hear ev_class
203 for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
205 int priority = scm_to_int (scm_cdar (disp));
206 Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
207 d->internal_add_listener (GET_LISTENER (dispatch), ev_class, priority);
209 listen_classes_ = scm_cons (ev_class, listen_classes_);
211 SCM entry = scm_cons (scm_from_int (priority), l.smobbed_copy ());
212 list = scm_merge (list, scm_list_1 (entry), ly_lily_module_constant ("car<"));
213 scm_hashq_set_x (listeners_, ev_class, list);
217 Dispatcher::remove_listener (Listener l, SCM ev_class)
219 SCM list = scm_hashq_ref (listeners_, ev_class, SCM_EOL);
223 programming_error ("remove_listener called with incorrect class.");
227 // We just remove the listener once.
230 SCM dummy = scm_cons (SCM_EOL, list);
232 while (scm_is_pair (scm_cdr (e)))
233 if (*unsmob_listener (scm_cdadr (e)) == l && first)
235 scm_set_cdr_x (e, scm_cddr (e));
241 list = scm_cdr (dummy);
242 scm_hashq_set_x (listeners_, ev_class, list);
245 warning ("Attempting to remove nonexisting listener.");
246 else if (!scm_is_pair (list))
248 /* Unregister with all dispatchers. */
249 for (SCM disp = dispatchers_; scm_is_pair (disp); disp = scm_cdr (disp))
251 Dispatcher *d = unsmob_dispatcher (scm_caar (disp));
252 d->remove_listener (GET_LISTENER (dispatch), ev_class);
254 listen_classes_ = scm_delq_x (ev_class, listen_classes_);
258 /* Register as a listener to another dispatcher. */
260 Dispatcher::register_as_listener (Dispatcher *disp)
262 int priority = ++disp->priority_count_;
264 // Don't register twice to the same dispatcher.
265 if (scm_assq (disp->self_scm (), dispatchers_) != SCM_BOOL_F)
267 warning ("Already listening to dispatcher, ignoring request");
271 dispatchers_ = scm_acons (disp->self_scm (), scm_from_int (priority), dispatchers_);
273 Listener list = GET_LISTENER (dispatch);
274 for (SCM cl = listen_classes_; scm_is_pair (cl); cl = scm_cdr (cl))
276 disp->internal_add_listener (list, scm_car (cl), priority);
280 /* Unregister as a listener to another dispatcher. */
282 Dispatcher::unregister_as_listener (Dispatcher *disp)
284 dispatchers_ = scm_assq_remove_x (dispatchers_, disp->self_scm ());
286 Listener listener = GET_LISTENER (dispatch);
287 for (SCM cl = listen_classes_; scm_is_pair (cl); cl = scm_cdr (cl))
289 disp->remove_listener (listener, scm_car (cl));