util/set: add a set_clear function

Clear a set back to the state of having zero entries.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/util/set.c

@@ -155,6 +155,29 @@ _mesa_set_destroy(struct set *ht, void (*delete_function)(struct set_entry *entr
    ralloc_free(ht);
 }
 
+/**
+ * Clears all values from the given set.
+ *
+ * If delete_function is passed, it gets called on each entry present before
+ * the set is cleared.
+ */
+void
+_mesa_set_clear(struct set *set, void (*delete_function)(struct set_entry *entry))
+{
+   struct set_entry *entry;
+
+   if (!set)
+      return;
+
+   set_foreach (set, entry) {
+      if (delete_function)
+         delete_function(entry);
+      entry->key = deleted_key;
+   }
+
+   set->entries = set->deleted_entries = 0;
+}
+
 /**
  * Finds a set entry with the given key and hash of that key.
  *

src/util/set.h

@@ -61,6 +61,9 @@ _mesa_set_create(void *mem_ctx,
 void
 _mesa_set_destroy(struct set *set,
                   void (*delete_function)(struct set_entry *entry));
+void
+_mesa_set_clear(struct set *set,
+                void (*delete_function)(struct set_entry *entry));
 
 struct set_entry *
 _mesa_set_add(struct set *set, const void *key);