Use comparator in sorting

Headers/Foundation/NSSortDescriptor.h

@@ -103,6 +103,14 @@ extern "C" {
 + (id)sortDescriptorWithKey: (NSString *)key 
                   ascending: (BOOL)ascending 
                  comparator: (NSComparator)cmptr;
+
+/** <init />
+ * Initialises the receiver to perform comparisons in the specified order
+ * using the comparator to compare the property key of each object.
+ */
+- (id) initWithKey: (NSString *)key
+         ascending: (BOOL)ascending
+        comparator: (NSComparator)cmptr;
 #endif
 
 /** Initialises the receiver for comparisons using the 'compare:' selector
@@ -113,12 +121,13 @@ extern "C" {
 
 /** <init />
  * Initialises the receiver to perform comparisons in the specified order
- * using selector to compar the property key of each object.
+ * using selector to compare the property key of each object.
  */
 - (id) initWithKey: (NSString *)key
          ascending: (BOOL)ascending
           selector: (SEL)selector;
 
+
 /** Returns the key used to obtain the property on which comparisons are based.
  */
 - (NSString *) key;

Source/NSSortDescriptor.m

@@ -113,8 +113,16 @@ static BOOL     initialized = NO;
   id comparedKey1 = [object1 valueForKeyPath: _key];
   id comparedKey2 = [object2 valueForKeyPath: _key];
 
-  result = (NSComparisonResult) [comparedKey1 performSelector: _selector
+  if(_comparator != NULL)
-                                                   withObject: comparedKey2];
+    {
+      result = CALL_BLOCK(((NSComparator)_comparator), comparedKey1, comparedKey2);
+    }
+  else
+    {
+      result = (NSComparisonResult) [comparedKey1 performSelector: _selector
+                                                       withObject: comparedKey2];
+    }
+  
   if (_ascending == NO)
     {
       if (result == NSOrderedAscending)
@@ -132,12 +140,23 @@ static BOOL     initialized = NO;
 
 - (id) copyWithZone: (NSZone*)zone
 {
+  NSSortDescriptor *copy = nil;
   if (NSShouldRetainWithZone(self, zone))
     {
       return RETAIN(self);
     }
-  return [[NSSortDescriptor allocWithZone: zone]
+
-    initWithKey: _key ascending: _ascending selector: _selector];
+  if(_comparator == NULL)
+    {
+      copy = [[NSSortDescriptor allocWithZone: zone]
+               initWithKey: _key ascending: _ascending selector: _selector];
+    }
+  else
+    {
+      copy = [[NSSortDescriptor allocWithZone: zone]
+               initWithKey: _key ascending: _ascending comparator: _comparator];
+    }
+  return copy;
 }
 
 - (void) dealloc
@@ -171,7 +190,10 @@ static BOOL     initialized = NO;
                   ascending: (BOOL)ascending 
                  comparator: (NSComparator)cmptr
 {
-  return nil;
+  return AUTORELEASE([[self alloc] initWithKey: key
+                                     ascending: ascending
+                                    comparator: cmptr]);
+  
 }
 
 - (id) initWithKey: (NSString *) key ascending: (BOOL) ascending
@@ -179,6 +201,37 @@ static BOOL     initialized = NO;
   return [self initWithKey: key ascending: ascending selector: NULL];
 }
 
+- (id) initWithKey: (NSString *) key
+         ascending: (BOOL) ascending
+        comparator: (NSComparator) cmptr
+{
+  if ([self init])
+    {
+      if (key == nil)
+        {
+          [NSException raise: NSInvalidArgumentException
+                      format: @"%@", _(@"Passed nil key when initializing "
+                                       @"an NSSortDescriptor.")];
+        }
+      if (cmptr == NULL)
+        {
+          [NSException raise: NSInvalidArgumentException
+                      format: @"%@", _(@"Passed NULL comparator when initializing "
+                                       @"an NSSortDescriptor.")];
+        }
+
+      ASSIGN(_key, key);
+      _ascending = ascending;
+      _comparator = cmptr;
+
+      return self;
+    }
+  else
+    {
+      return nil;
+    }
+}
+
 - (id) initWithKey: (NSString *) key
          ascending: (BOOL) ascending
           selector: (SEL) selector