+void xbt_lib_unset(xbt_lib_t lib, const char *key, int level, int invoke_callback)
+{
+ void **elts = xbt_dict_get_or_null(lib->dict, key);
+ if (!elts) {
+ XBT_WARN("no key %s", key);
+ return;
+ }
+
+ void *obj = elts[level];
+ if (!obj) {
+ XBT_WARN("no key %s at level %d", key, level);
+ return;
+ }
+
+ XBT_DEBUG("Remove %p of key %s at level %d", obj, key, level);
+ elts[level] = NULL;
+
+ /* check if there still remains any elements of this key */
+ int empty = 1;
+ int i;
+ for (i = 0; i < lib->levels && empty; i++) {
+ if (elts[i] != NULL)
+ empty = 0;
+ }
+ if (empty) {
+ /* there is no element at any level, so delete the key */
+ xbt_dict_remove(lib->dict, key);
+ }
+
+ if (invoke_callback)
+ lib->free_f[level](obj);
+}
+