added function to check if hash table value exists for a given key

[rocksndiamonds.git] / src / libgame / hash.c

diff --git a/src/libgame/hash.c b/src/libgame/hash.c
index 101ec1214a30aae2faddd478c24f53321d401832..89c7134f5906aa06d8a6cb24813eebf84f2d42af 100644 (file)
--- a/src/libgame/hash.c
+++ b/src/libgame/hash.c
@@ -268,6 +268,29 @@ hashtable_change(struct hashtable *h, void *k, void *v)
   return 0;
 }
 
+/*****************************************************************************/
+int /* checks if key exists */
+hashtable_exists(struct hashtable *h, void *k)
+{
+  struct entry *e;
+  unsigned int hashvalue, index;
+
+  hashvalue = hash(h, k);
+  index = indexFor(h->tablelength, hashvalue);
+  e = h->table[index];
+
+  while (e != NULL)
+  {
+    /* Check hash value to short circuit heavier comparison */
+    if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
+      return 1;
+
+    e = e->next;
+  }
+
+  return 0;
+}
+
 /*****************************************************************************/
 void * /* returns value associated with key */
 hashtable_search(struct hashtable *h, void *k)