1 files changed, 39 insertions, 0 deletions
diff --git a/src/lib/priorityq.h b/src/lib/priorityq.h
new file mode 100644
index 0000000..aa38914
--- /dev/null
+++ b/src/lib/priorityq.h
@@ -0,0 +1,39 @@
+#ifndef PRIORITYQ_H
+#define PRIORITYQ_H
+
+/* Priority queue implementation using heap. The items you add to the queue
+   must begin with a struct priorityq_item. This is necessary for
+   priorityq_remove() to work fast. */
+
+struct priorityq_item {
+	/* Current index in the queue array, updated automatically. */
+	unsigned int idx;
+	/* [your own data] */
+};
+
+/* Returns <0, 0 or >0 */
+typedef int priorityq_cmp_callback_t(const void *p1, const void *p2);
+
+/* Create a new priority queue. Callback is used to compare added items. */
+struct priorityq *
+priorityq_init(priorityq_cmp_callback_t *cmp_callback, unsigned int init_size);
+void priorityq_deinit(struct priorityq **pq);
+
+/* Return number of items in the queue. */
+unsigned int priorityq_count(const struct priorityq *pq) ATTR_PURE;
+
+/* Add a new item to the queue. */
+void priorityq_add(struct priorityq *pq, struct priorityq_item *item);
+/* Remove the specified item from the queue. */
+void priorityq_remove(struct priorityq *pq, struct priorityq_item *item);
+
+/* Return the item with the highest priority. Returns NULL if queue is empty. */
+struct priorityq_item *priorityq_peek(struct priorityq *pq);
+/* Like priorityq_peek(), but also remove the returned item from the queue. */
+struct priorityq_item *priorityq_pop(struct priorityq *pq);
+/* Returns array containing all the priorityq_items. Only the first item is
+   guaranteed to be the highest priority item, the rest can't be assumed to
+   be in any order. */
+struct priorityq_item *const *priorityq_items(struct priorityq *pq);
+
+#endif