Address other comments

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -375,8 +375,6 @@
 		E597E3C61E817B2800451596 /* ASCollectionLayout+Subclasses.h in Headers */ = {isa = PBXBuildFile; fileRef = E597E3C51E817B2800451596 /* ASCollectionLayout+Subclasses.h */; };
 		E597E3C81E817FB500451596 /* ASDataControllerLayoutContext.h in Headers */ = {isa = PBXBuildFile; fileRef = E597E3C71E817FB500451596 /* ASDataControllerLayoutContext.h */; };
 		E597E3CA1E81800500451596 /* ASDataControllerLayoutContext.m in Sources */ = {isa = PBXBuildFile; fileRef = E597E3C91E81800500451596 /* ASDataControllerLayoutContext.m */; };
-		E5ABAC761E8551B3007AC15C /* ASCollectionLayoutHelpers.h in Headers */ = {isa = PBXBuildFile; fileRef = E5ABAC751E8551B3007AC15C /* ASCollectionLayoutHelpers.h */; };
-		E5ABAC781E85528A007AC15C /* ASCollectionLayoutHelpers.m in Sources */ = {isa = PBXBuildFile; fileRef = E5ABAC771E85528A007AC15C /* ASCollectionLayoutHelpers.m */; };
 		E5ABAC7B1E8564EE007AC15C /* ASRectTable.h in Headers */ = {isa = PBXBuildFile; fileRef = E5ABAC791E8564EE007AC15C /* ASRectTable.h */; };
 		E5ABAC7C1E8564EE007AC15C /* ASRectTable.m in Sources */ = {isa = PBXBuildFile; fileRef = E5ABAC7A1E8564EE007AC15C /* ASRectTable.m */; };
 		E5B077E61E6843A600C24B5B /* ASCollectionLayout.h in Headers */ = {isa = PBXBuildFile; fileRef = E5B077E11E6843A600C24B5B /* ASCollectionLayout.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -786,19 +784,17 @@
 		E5711A2D1C840C96009619D4 /* ASCollectionElement.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASCollectionElement.mm; sourceTree = "<group>"; };
 		E579BC961E84203D00E24C78 /* ASCollectionNode+FrameworkPrivate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASCollectionNode+FrameworkPrivate.h"; sourceTree = "<group>"; };
 		E597E3C31E81748900451596 /* ASDataController+Beta.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASDataController+Beta.h"; sourceTree = "<group>"; };
-		E597E3C51E817B2800451596 /* ASCollectionLayout+Subclasses.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASCollectionLayout+Subclasses.h"; sourceTree = "<group>"; };
+		E597E3C51E817B2800451596 /* ASCollectionLayout+Subclasses.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; lineEnding = 0; path = "ASCollectionLayout+Subclasses.h"; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
 		E597E3C71E817FB500451596 /* ASDataControllerLayoutContext.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASDataControllerLayoutContext.h; sourceTree = "<group>"; };
 		E597E3C91E81800500451596 /* ASDataControllerLayoutContext.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASDataControllerLayoutContext.m; sourceTree = "<group>"; };
-		E5ABAC751E8551B3007AC15C /* ASCollectionLayoutHelpers.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASCollectionLayoutHelpers.h; sourceTree = "<group>"; };
-		E5ABAC771E85528A007AC15C /* ASCollectionLayoutHelpers.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASCollectionLayoutHelpers.m; sourceTree = "<group>"; };
 		E5ABAC791E8564EE007AC15C /* ASRectTable.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASRectTable.h; sourceTree = "<group>"; };
 		E5ABAC7A1E8564EE007AC15C /* ASRectTable.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASRectTable.m; sourceTree = "<group>"; };
 		E5B077E11E6843A600C24B5B /* ASCollectionLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASCollectionLayout.h; sourceTree = "<group>"; };
-		E5B077F41E68576B00C24B5B /* ASCollectionLayout.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASCollectionLayout.mm; sourceTree = "<group>"; };
+		E5B077F41E68576B00C24B5B /* ASCollectionLayout.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; lineEnding = 0; path = ASCollectionLayout.mm; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
 		E5B077FD1E69F4EB00C24B5B /* ASElementMap.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASElementMap.h; sourceTree = "<group>"; };
 		E5B077FE1E69F4EB00C24B5B /* ASElementMap.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASElementMap.m; sourceTree = "<group>"; };
 		E5B0780A1E6A01E200C24B5B /* ASCollectionFlowLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASCollectionFlowLayout.h; sourceTree = "<group>"; };
-		E5B0780B1E6A01E200C24B5B /* ASCollectionFlowLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASCollectionFlowLayout.m; sourceTree = "<group>"; };
+		E5B0780B1E6A01E200C24B5B /* ASCollectionFlowLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; lineEnding = 0; path = ASCollectionFlowLayout.m; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objc; };
 		E5E281731E71C833006B67C2 /* ASCollectionLayoutState.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASCollectionLayoutState.h; sourceTree = "<group>"; };
 		E5E281751E71C845006B67C2 /* ASCollectionLayoutState.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASCollectionLayoutState.m; sourceTree = "<group>"; };
 		EFA731F0396842FF8AB635EE /* libPods-AsyncDisplayKitTests.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-AsyncDisplayKitTests.a"; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -1420,8 +1416,6 @@
 				E5B077F41E68576B00C24B5B /* ASCollectionLayout.mm */,
 				E5B0780A1E6A01E200C24B5B /* ASCollectionFlowLayout.h */,
 				E5B0780B1E6A01E200C24B5B /* ASCollectionFlowLayout.m */,
-				E5ABAC751E8551B3007AC15C /* ASCollectionLayoutHelpers.h */,
-				E5ABAC771E85528A007AC15C /* ASCollectionLayoutHelpers.m */,
 			);
 			name = "Collection Layout";
 			sourceTree = "<group>";
@@ -1548,7 +1542,6 @@
 				B35062521B010EFD0018CF92 /* ASDisplayNodeInternal.h in Headers */,
 				AC7A2C181BDE11DF0093FE1A /* ASTableViewInternal.h in Headers */,
 				B35062531B010EFD0018CF92 /* ASImageNode+CGExtras.h in Headers */,
-				E5ABAC761E8551B3007AC15C /* ASCollectionLayoutHelpers.h in Headers */,
 				254C6B7F1BF94DF4003EC431 /* ASTextKitTruncating.h in Headers */,
 				CC58AA4B1E398E1D002C8CB4 /* ASBlockTypes.h in Headers */,
 				6977965F1D8AC8D3007E93D7 /* ASLayoutSpec+Subclasses.h in Headers */,
@@ -1994,7 +1987,6 @@
 				DB78412E1C6BCE1600A9E2B4 /* _ASTransitionContext.m in Sources */,
 				B350620B1B010EFD0018CF92 /* ASTableView.mm in Sources */,
 				B350620E1B010EFD0018CF92 /* ASTextNode.mm in Sources */,
-				E5ABAC781E85528A007AC15C /* ASCollectionLayoutHelpers.m in Sources */,
 				6959433F1D70815300B0EE1F /* ASDisplayNodeLayout.mm in Sources */,
 				68355B3E1CB57A60001D4E68 /* ASPINRemoteImageDownloader.m in Sources */,
 				CC034A141E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.m in Sources */,

Source/Details/ASCollectionFlowLayout.h

@@ -9,8 +9,14 @@
 #import <AsyncDisplayKit/ASCollectionLayout.h>
 #import <AsyncDisplayKit/ASScrollDirection.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
+AS_SUBCLASSING_RESTRICTED
+
 @interface ASCollectionFlowLayout : ASCollectionLayout
 
 - (instancetype)initWithScrollableDirections:(ASScrollDirection)scrollableDirections;
 
 @end
+
+NS_ASSUME_NONNULL_END

Source/Details/ASCollectionFlowLayout.m

@@ -11,7 +11,6 @@
 #import <AsyncDisplayKit/ASCellNode.h>
 #import <AsyncDisplayKit/ASCollectionLayoutState.h>
 #import <AsyncDisplayKit/ASCollectionElement.h>
-#import <AsyncDisplayKit/ASCollectionLayoutHelpers.h>
 #import <AsyncDisplayKit/ASDataControllerLayoutContext.h>
 #import <AsyncDisplayKit/ASElementMap.h>
 #import <AsyncDisplayKit/ASLayout.h>
@@ -53,7 +52,7 @@ - (ASSizeRange)sizeRangeThatFits:(CGSize)viewportSize
   return sizeRange;
 }
 
-- (ASCollectionLayoutState *)calculateLayoutForLayoutContext:(ASDataControllerLayoutContext *)context
+- (ASCollectionLayoutState *)calculateLayoutWithContext:(ASDataControllerLayoutContext *)context
 {
   ASElementMap *elementMap = context.elementMap;
   NSMutableArray<ASCellNode *> *children = ASArrayByFlatMapping(elementMap.itemElements, ASCollectionElement *element, element.node);
@@ -72,39 +71,7 @@ - (ASCollectionLayoutState *)calculateLayoutForLayoutContext:(ASDataControllerLa
                                                                         children:children];
   stackSpec.concurrent = YES;
   ASLayout *layout = [stackSpec layoutThatFits:[self sizeRangeThatFits:context.viewportSize]];
-  return ASLayoutToCollectionContentAttributes(layout, elementMap);
-}
-
-- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect
-{
-  NSMutableArray *attributesInRect = [NSMutableArray array];
-  NSMapTable *attrsMap = self.currentContentAttributes.elementToLayoutArrtibutesMap;
-  for (ASCollectionElement *element in attrsMap) {
-    UICollectionViewLayoutAttributes *attrs = [attrsMap objectForKey:element];
-    if (CGRectIntersectsRect(rect, attrs.frame)) {
-      [attributesInRect addObject:attrs];
-    }
-  }
-  return attributesInRect;
-}
-
-- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
-{
-  ASCollectionLayoutState *state = self.currentContentAttributes;
-  ASCollectionElement *element = [state.elementMap elementForItemAtIndexPath:indexPath];
-  return [state.elementToLayoutArrtibutesMap objectForKey:element];
-}
-
-- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
-{
-  ASCollectionLayoutState *state = self.currentContentAttributes;
-  ASCollectionElement *element = [state.elementMap supplementaryElementOfKind:elementKind atIndexPath:indexPath];
-  return [state.elementToLayoutArrtibutesMap objectForKey:element];
-}
-
-- (UICollectionViewLayoutAttributes *)layoutAttributesForDecorationViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
-{
-  return [self layoutAttributesForSupplementaryViewOfKind:elementKind atIndexPath:indexPath];
+  return [[ASCollectionLayoutState alloc] initWithElementMap:elementMap layout:layout];
 }
 
 @end

Source/Details/ASCollectionLayout+Subclasses.h

@@ -15,9 +15,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface ASCollectionLayout () <ASDataControllerLayoutDelegate>
 
-/// The current state of this layout object, if any. This property must be accessed on main thread.
-@property (nonatomic, strong, nullable) ASCollectionLayoutState *state;
-
 /**
  * @abstract Prepares and returns a new layout for given context.
  *
@@ -32,7 +29,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * @discussion This method must block its calling thread but can dispatch to other theads to reduce blocking time.
  */
-- (ASCollectionLayoutState *)calculateLayoutForLayoutContext:(ASDataControllerLayoutContext *)context;
+- (ASCollectionLayoutState *)calculateLayoutWithContext:(ASDataControllerLayoutContext *)context;
 
 @end
 

Source/Details/ASCollectionLayout.h

@@ -39,8 +39,6 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, weak) ASCollectionNode *collectionNode;
 
-- (instancetype)init NS_DESIGNATED_INITIALIZER;
-
 - (instancetype)initWithCoder:(NSCoder *)aDecoder __unavailable;
 
 @end

Source/Details/ASCollectionLayout.mm

@@ -35,25 +35,6 @@ @interface ASCollectionLayout () {
 
 @implementation ASCollectionLayout
 
-- (instancetype)init
-{
-  return [super init];
-}
-
-- (ASCollectionLayoutState *)state
-{
-  ASDisplayNodeAssertMainThread();
-  return _state;
-}
-
-- (void)setState:(ASCollectionLayoutState *)newState
-{
-  ASDisplayNodeAssertMainThread();
-  if (! ASObjectIsEqual(_state, newState)) {
-    _state = newState;
-  }
-}
-
 #pragma mark - ASDataControllerLayoutDelegate
 
 - (ASDataControllerLayoutContext *)layoutContextWithElementMap:(ASElementMap *)map
@@ -64,7 +45,7 @@ - (ASDataControllerLayoutContext *)layoutContextWithElementMap:(ASElementMap *)m
 
 - (void)prepareLayoutForLayoutContext:(ASDataControllerLayoutContext *)context
 {
-  ASCollectionLayoutState *state = [self calculateLayoutForLayoutContext:context];
+  ASCollectionLayoutState *state = [self calculateLayoutWithContext:context];
 
   ASDN::MutexLocker l(__instanceLock__);
   _pendingState = state;
@@ -90,7 +71,7 @@ - (void)prepareLayout
   }
 
   if (state == nil) {
-    state = [self calculateLayoutForLayoutContext:context];
+    state = [self calculateLayoutWithContext:context];
   }
 
   _state = state;
@@ -106,12 +87,40 @@ - (void)invalidateLayout
 - (CGSize)collectionViewContentSize
 {
   ASDisplayNodeAssertMainThread();
+  ASDisplayNodeAssertNotNil(_state, @"Collection layout state should not be nil at this point");
   return _state.contentSize;
 }
 
+- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect
+{
+  NSMutableArray *attributesInRect = [NSMutableArray array];
+  NSMapTable *attrsMap = _state.elementToLayoutArrtibutesMap;
+  for (ASCollectionElement *element in attrsMap) {
+    UICollectionViewLayoutAttributes *attrs = [attrsMap objectForKey:element];
+    if (CGRectIntersectsRect(rect, attrs.frame)) {
+      [attributesInRect addObject:attrs];
+    }
+  }
+  return attributesInRect;
+}
+
+- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  ASCollectionLayoutState *state = _state;
+  ASCollectionElement *element = [state.elementMap elementForItemAtIndexPath:indexPath];
+  return [state.elementToLayoutArrtibutesMap objectForKey:element];
+}
+
+- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
+{
+  ASCollectionLayoutState *state = _state;
+  ASCollectionElement *element = [state.elementMap supplementaryElementOfKind:elementKind atIndexPath:indexPath];
+  return [state.elementToLayoutArrtibutesMap objectForKey:element];
+}
+
 #pragma mark - Subclass hooks
 
-- (ASCollectionLayoutState *)calculateLayoutForLayoutContext:(ASDataControllerLayoutContext *)context
+- (ASCollectionLayoutState *)calculateLayoutWithContext:(ASDataControllerLayoutContext *)context
 {
   // Subclass hooks
   ASDisplayNodeAssertLockUnownedByCurrentThread(__instanceLock__);

Source/Details/ASCollectionLayoutState.h

@@ -10,7 +10,7 @@
 #import <UIKit/UIKit.h>
 #import <AsyncDisplayKit/ASBaseDefines.h>
 
-@class ASElementMap, ASCollectionElement;
+@class ASElementMap, ASCollectionElement, ASLayout;
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -33,10 +33,22 @@ AS_SUBCLASSING_RESTRICTED
  *
  * @param contentSize The content size of the collection's layout
  *
- * @param elementToLayoutArrtibutesMap Map between elements to their layout attributes. The map may contain all elements, or a subset of them and to be updated later. Should use weak pointers for elements.
+ * @param elementToLayoutArrtibutesMap Map between elements to their layout attributes. The map may contain all elements, or a subset of them and will be updated later. 
+ * Also, it should have NSMapTableObjectPointerPersonality and NSMapTableWeakMemory as key options.
  */
 - (instancetype)initWithElementMap:(ASElementMap *)elementMap contentSize:(CGSize)contentSize elementToLayoutArrtibutesMap:(NSMapTable<ASCollectionElement *, UICollectionViewLayoutAttributes *> *)attrsMap NS_DESIGNATED_INITIALIZER;
 
+/**
+ * Convenience initializer.
+ *
+ * @param elementMap The element map used to calculate this object
+ *
+ * @param layout The layout describes size and position of all elements, or a subset of them and will be updated later.
+ *
+ * @discussion The sublayouts that describe position of elements must be direct children of the root layout object parameter.
+ */
+- (instancetype)initWithElementMap:(ASElementMap *)elementMap layout:(ASLayout *)layout;
+
 @end
 
 NS_ASSUME_NONNULL_END

Source/Details/ASCollectionLayoutState.m

@@ -7,11 +7,37 @@
 //
 
 #import <AsyncDisplayKit/ASCollectionLayoutState.h>
+
 #import <AsyncDisplayKit/ASAssert.h>
+#import <AsyncDisplayKit/ASCellNode+Internal.h>
+#import <AsyncDisplayKit/ASCollectionElement.h>
 #import <AsyncDisplayKit/ASElementMap.h>
+#import <AsyncDisplayKit/ASLayout.h>
 
 @implementation ASCollectionLayoutState
 
+- (instancetype)initWithElementMap:(ASElementMap *)elementMap layout:(ASLayout *)layout
+{
+  NSMapTable<ASCollectionElement *, UICollectionViewLayoutAttributes *> *attrsMap = [NSMapTable mapTableWithKeyOptions:(NSMapTableObjectPointerPersonality | NSMapTableWeakMemory) valueOptions:NSMapTableStrongMemory];
+  for (ASLayout *sublayout in layout.sublayouts) {
+    ASCollectionElement *element = ((ASCellNode *)sublayout.layoutElement).collectionElement;
+    NSIndexPath *indexPath = [elementMap indexPathForElement:element];
+    NSString *supplementaryElementKind = element.supplementaryElementKind;
+
+    UICollectionViewLayoutAttributes *attrs;
+    if (supplementaryElementKind == nil) {
+      attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
+    } else {
+      attrs = [UICollectionViewLayoutAttributes layoutAttributesForSupplementaryViewOfKind:supplementaryElementKind withIndexPath:indexPath];
+    }
+
+    attrs.frame = sublayout.frame;
+    [attrsMap setObject:attrs forKey:element];
+  }
+
+  return [self initWithElementMap:elementMap contentSize:layout.size elementToLayoutArrtibutesMap:attrsMap];
+}
+
 - (instancetype)initWithElementMap:(ASElementMap *)elementMap contentSize:(CGSize)contentSize elementToLayoutArrtibutesMap:(NSMapTable<ASCollectionElement *,UICollectionViewLayoutAttributes *> *)attrsMap
 {
   self = [super init];