+
+typedef void (*topo_sort_set_fn_t)(struct commit*, void *data);
+typedef void* (*topo_sort_get_fn_t)(struct commit*);
+
+void topo_sort_default_setter(struct commit *c, void *data);
+void *topo_sort_default_getter(struct commit *c);
+
+void sort_in_topological_order(struct commit_list ** list, int lifo);
+void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
+ topo_sort_set_fn_t setter,
+ topo_sort_get_fn_t getter);