1 files changed, 112 insertions, 0 deletions
diff --git a/Foundation/GTMNSArray+Merge.m b/Foundation/GTMNSArray+Merge.m
new file mode 100644
index 0000000..725aa8a
--- /dev/null
+++ b/Foundation/GTMNSArray+Merge.m
@@ -0,0 +1,112 @@
+//
+//  GTMNSArray+Merge.m
+//
+//  Copyright 2008 Google Inc.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
+//  use this file except in compliance with the License.  You may obtain a copy
+//  of the License at
+// 
+//  http://www.apache.org/licenses/LICENSE-2.0
+// 
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+//  License for the specific language governing permissions and limitations 
+//  under the License.
+//
+
+#import "GTMNSArray+Merge.h"
+
+#import "GTMDefines.h"
+
+#if GTM_IPHONE_SDK
+#import <objc/message.h>
+#else  // GTM_IPHONE_SDK
+#import <objc/objc-runtime.h>
+#endif  // GTM_IPHONE_SDK
+
+@implementation NSArray (GTMNSArrayMergingAdditions)
+
+- (NSArray *)gtm_mergeArray:(NSArray *)newArray
+              mergeSelector:(SEL)merger {
+  return [self gtm_mergeArray:newArray
+              compareSelector:@selector(compare:)
+                mergeSelector:merger];
+}
+
+- (NSArray *)gtm_mergeArray:(NSArray *)newArray
+            compareSelector:(SEL)comparer
+              mergeSelector:(SEL)merger {
+  // must have a compare selector
+  if (!comparer) return nil;
+
+  // Sort and merge the contents of |self| with |newArray|.
+  NSArray *sortedMergedArray = nil;
+  if ([self count] && [newArray count]) {
+    NSMutableArray *mergingArray = [self mutableCopy];
+    [mergingArray sortUsingSelector:comparer];
+    NSArray *sortedNewArray
+      = [newArray sortedArrayUsingSelector:comparer];
+    
+    NSUInteger oldIndex = 0;
+    NSUInteger oldCount = [mergingArray count];
+    id oldItem = (oldIndex < oldCount)
+                 ? [mergingArray objectAtIndex:0]
+                 : nil;
+    
+    id newItem = nil;
+    NSEnumerator *itemEnum = [sortedNewArray objectEnumerator];
+    while ((newItem = [itemEnum nextObject])) {
+      BOOL stillLooking = YES;
+      while (oldIndex < oldCount && stillLooking) {
+        // We must take care here, since Intel leaves junk in high bytes of
+        // return register for predicates that return BOOL.
+        // For details see: 
+        // http://developer.apple.com/documentation/MacOSX/Conceptual/universal_binary/universal_binary_tips/chapter_5_section_23.html
+        // and
+        // http://www.red-sweater.com/blog/320/abusing-objective-c-with-class#comment-83187
+        NSComparisonResult result
+          = ((NSComparisonResult (*)(id, SEL, id))objc_msgSend)(newItem, comparer, oldItem);
+        if (result == NSOrderedSame && merger) {
+          // It's a match!
+          id repItem = [oldItem performSelector:merger
+                                     withObject:newItem];
+          [mergingArray replaceObjectAtIndex:oldIndex
+                                  withObject:repItem];
+          ++oldIndex;
+          oldItem = (oldIndex < oldCount)
+                    ? [mergingArray objectAtIndex:oldIndex]
+                    : nil;
+          stillLooking = NO;
+        } else if (result == NSOrderedAscending
+                   || (result == NSOrderedSame && !merger)) {
+          // This is either a new item and belongs right here, or it's
+          // a match to an existing item but we're not merging.
+          [mergingArray insertObject:newItem
+                             atIndex:oldIndex];
+          ++oldIndex;
+          ++oldCount;
+          stillLooking = NO;
+        } else {
+          ++oldIndex;
+          oldItem = (oldIndex < oldCount)
+                    ? [mergingArray objectAtIndex:oldIndex]
+                    : nil;
+        }
+      }
+      if (stillLooking) {
+        // Once we get here, the rest of the new items get appended.
+        [mergingArray addObject:newItem];
+      }
+    }
+    sortedMergedArray = mergingArray;
+  } else if ([self count]) {
+    sortedMergedArray = [self sortedArrayUsingSelector:comparer];
+  } else if ([newArray count]) {
+    sortedMergedArray = [newArray sortedArrayUsingSelector:comparer];
+  }
+  return sortedMergedArray;
+}
+
+@end