typedef struct Prioq Prioq;
+#define PRIOQ_IDX_NULL ((unsigned) -1)
+
Prioq *prioq_new(compare_func_t compare);
void prioq_free(Prioq *q);
int prioq_ensure_allocated(Prioq **q, compare_func_t compare_func);
int prioq_remove(Prioq *q, void *data, unsigned *idx);
int prioq_reshuffle(Prioq *q, void *data, unsigned *idx);
-void *prioq_peek(Prioq *q);
+void *prioq_peek(Prioq *q) _pure_;
void *prioq_pop(Prioq *q);
-unsigned prioq_size(Prioq *q);
-bool prioq_isempty(Prioq *q);
+unsigned prioq_size(Prioq *q) _pure_;
+bool prioq_isempty(Prioq *q) _pure_;