From 2d633f118bddd4b9abeefc87dcac41122d97a8ed Mon Sep 17 00:00:00 2001
From: Adlai Holler <guy.on.internet@icloud.com>
Date: Tue, 24 Nov 2015 18:44:10 -0800
Subject: [PATCH] Fix it better

---
 .../Private/_ASHierarchyChangeSet.m           | 91 +++++++++----------
 1 file changed, 43 insertions(+), 48 deletions(-)

diff --git a/AsyncDisplayKit/Private/_ASHierarchyChangeSet.m b/AsyncDisplayKit/Private/_ASHierarchyChangeSet.m
index d35748c849..c4d9af059f 100644
--- a/AsyncDisplayKit/Private/_ASHierarchyChangeSet.m
+++ b/AsyncDisplayKit/Private/_ASHierarchyChangeSet.m
@@ -217,38 +217,35 @@
   // Create new changes by grouping sorted changes by animation option
   NSMutableArray *result = [NSMutableArray new];
   
-  __block ASDataControllerAnimationOptions currentOptions = 0;
-  __block NSMutableIndexSet *currentIndexes = nil;
+  __block ASDataControllerAnimationOptions currentOptions = NSUIntegerMax;
+  __block NSMutableIndexSet *currentIndexes = [NSMutableIndexSet indexSet];
 
-  BOOL reverse = (type == _ASHierarchyChangeTypeDelete);
-  NSEnumerationOptions options = reverse ? NSEnumerationReverse : kNilOptions;
-  NSUInteger endIndex = reverse ? allIndexes.firstIndex : allIndexes.lastIndex;
+  NSEnumerationOptions options = type == _ASHierarchyChangeTypeDelete ? NSEnumerationReverse : kNilOptions;
 
   [allIndexes enumerateIndexesWithOptions:options usingBlock:^(NSUInteger idx, __unused BOOL * stop) {
     ASDataControllerAnimationOptions options = [animationOptions[@(idx)] integerValue];
-    BOOL endingCurrentGroup = NO;
-    
-    if (currentIndexes == nil) {
-      // Starting a new group
-      currentIndexes = [NSMutableIndexSet indexSetWithIndex:idx];
-      currentOptions = options;
-    } else if (options == currentOptions) {
-      // Continuing the current group
-      [currentIndexes addIndex:idx];
-    } else {
-      endingCurrentGroup = YES;
-    }
-    
-    BOOL endingLastGroup = (currentIndexes != nil && endIndex == idx);
-    
-    if (endingCurrentGroup || endingLastGroup) {
-      _ASHierarchySectionChange *change = [[_ASHierarchySectionChange alloc] initWithChangeType:type indexSet:currentIndexes animationOptions:currentOptions];
+
+    // End the previous group if needed.
+    if (options != currentOptions && currentIndexes.count > 0) {
+      _ASHierarchySectionChange *change = [[_ASHierarchySectionChange alloc] initWithChangeType:type indexSet:[currentIndexes copy] animationOptions:currentOptions];
       [result addObject:change];
-      currentOptions = 0;
-      currentIndexes = nil;
+      [currentIndexes removeAllIndexes];
     }
+
+    // Start a new group if needed.
+    if (currentIndexes.count == 0) {
+      currentOptions = options;
+    }
+
+    [currentIndexes addIndex:idx];
   }];
-  
+
+  // Finish up the last group.
+  if (currentIndexes.count > 0) {
+    _ASHierarchySectionChange *change = [[_ASHierarchySectionChange alloc] initWithChangeType:type indexSet:[currentIndexes copy] animationOptions:currentOptions];
+    [result addObject:change];
+  }
+
   [changes setArray:result];
 }
 
@@ -303,36 +300,34 @@
 
   // Create new changes by grouping sorted changes by animation option
   NSMutableArray *result = [NSMutableArray new];
-  
+
   ASDataControllerAnimationOptions currentOptions = 0;
-  NSMutableArray *currentIndexPaths = nil;
-  NSIndexPath *lastIndexPath = allIndexPaths.lastObject;
-  
+  NSMutableArray *currentIndexPaths = [NSMutableArray array];
+
   for (NSIndexPath *indexPath in allIndexPaths) {
     ASDataControllerAnimationOptions options = [animationOptions[indexPath] integerValue];
-    BOOL endingCurrentGroup = NO;
-    
-    if (currentIndexPaths == nil) {
-      // Starting a new group
-      currentIndexPaths = [NSMutableArray arrayWithObject:indexPath];
-      currentOptions = options;
-    } else if (options == currentOptions) {
-      // Continuing the current group
-      [currentIndexPaths addObject:indexPath];
-    } else {
-      endingCurrentGroup = YES;
-    }
-    
-    BOOL endingLastGroup = (currentIndexPaths != nil && (NSOrderedSame == [lastIndexPath compare:indexPath]));
 
-    if (endingCurrentGroup || endingLastGroup) {
-      _ASHierarchyItemChange *change = [[_ASHierarchyItemChange alloc] initWithChangeType:type indexPaths:currentIndexPaths animationOptions:currentOptions presorted:YES];
+    // End the previous group if needed.
+    if (options != currentOptions && currentIndexPaths.count > 0) {
+      _ASHierarchyItemChange *change = [[_ASHierarchyItemChange alloc] initWithChangeType:type indexPaths:[currentIndexPaths copy] animationOptions:currentOptions presorted:YES];
       [result addObject:change];
-      currentOptions = 0;
-      currentIndexPaths = nil;
+      [currentIndexPaths removeAllObjects];
     }
+
+    // Start a new group if needed.
+    if (currentIndexPaths.count == 0) {
+      currentOptions = options;
+    }
+
+    [currentIndexPaths addObject:indexPath];
   }
-  
+
+  // Finish up the last group.
+  if (currentIndexPaths.count > 0) {
+    _ASHierarchyItemChange *change = [[_ASHierarchyItemChange alloc] initWithChangeType:type indexPaths:[currentIndexPaths copy] animationOptions:currentOptions presorted:YES];
+    [result addObject:change];
+  }
+
   [changes setArray:result];
 }