Add methods from 10.8 for using zeroing weak references in collections.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@35877 72102866-910b-0410-8b05-ffd578937521

Headers/Foundation/NSHashTable.h

@@ -52,7 +52,9 @@ enum {
   NSHashTableCopyIn
     = NSPointerFunctionsCopyIn,
   NSHashTableObjectPointerPersonality
-    = NSPointerFunctionsObjectPointerPersonality
+    = NSPointerFunctionsObjectPointerPersonality,
+  NSHashTableWeakMemory
+    = NSPointerFunctionsWeakMemory
 };
 
 typedef NSUInteger NSHashTableOptions;
@@ -62,6 +64,14 @@ typedef NSUInteger NSHashTableOptions;
 + (id) hashTableWithOptions: (NSPointerFunctionsOptions)options;
 
 + (id) hashTableWithWeakObjects;
+/**
+ * Creates a hash table that uses zeroing weak references (either using the
+ * automatic reference counting or garbage collection mechanism, depending on
+ * which mode this framework is compiled in) so that objects are removed when
+ * their last other reference disappears.
+ */
++ (id) weakObjectsHashTable;
+
 
 - (id) initWithOptions: (NSPointerFunctionsOptions)options
 	      capacity: (NSUInteger)initialCapacity;