General-purpose event distribution interface

[disorder] / lib / eventdist.c

diff --git a/lib/eventdist.c b/lib/eventdist.c
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+++ b/lib/eventdist.c
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+/*
+ * This file is part of DisOrder
+ * Copyright (C) 2008 Richard Kettlewell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA
+ */
+
+#include "common.h"
+
+#include "mem.h"
+#include "eventdist.h"
+#include "hash.h"
+
+struct event_data {
+  struct event_data *next;
+  const char *event;
+  event_handler *callback;
+  void *callbackdata;
+};
+
+static hash *events;
+
+/** @brief Register an event handler
+ * @param event Event type to handle
+ * @param callback Function to call when event occurs
+ * @param callbackdata Passed to @p callback
+ * @return Handle for this registration (for use with event_cancel())
+ */
+event_handle event_register(const char *event,
+                            event_handler *callback,
+                            void *callbackdata) {
+  static const struct event_data *null;
+  struct event_data *ed = xmalloc(sizeof *ed), **head;
+
+  if(!events)
+    events = hash_new(sizeof (struct event_data *));
+  if(!(head = hash_find(events, event))) {
+    hash_add(events, event, &null, HASH_INSERT);
+    head = hash_find(events, event);
+  }
+  ed->next = *head;
+  ed->event = xstrdup(event);
+  ed->callback = callback;
+  ed->callbackdata = callbackdata;
+  *head = ed;
+  return ed;
+}
+
+/** @brief Stop handling an event
+ * @param handle Registration to cancel (as returned from event_register())
+ *
+ * @p handle is allowed to be NULL.
+ */
+void event_cancel(event_handle handle) {
+  struct event_data **head, **edp;
+  
+  if(!handle)
+    return;
+  assert(events);
+  head = hash_find(events, handle->event);
+  for(edp = head; *edp && *edp != handle; edp = &(*edp)->next)
+    ;
+  assert(*edp == handle);
+  *edp = handle->next;
+}
+
+/** @brief Raise an event
+ * @param event Event type to raise
+ * @param eventdata Event-specific data
+ */
+void event_raise(const char *event,
+                 void *eventdata) {
+  struct event_data *ed, **head;
+  if(!events)
+    return;
+  if(!(head = hash_find(events, event)))
+    return;
+  for(ed = *head; ed; ed = ed->next)
+    ed->callback(event, eventdata, ed->callbackdata);
+}
+
+/*
+Local Variables:
+c-basic-offset:2
+comment-column:40
+fill-column:79
+indent-tabs-mode:nil
+End:
+*/