Add first-pass view model support to collection node. #trivial (#356)

* Add first-pass view model support for collection node. Much more to come!

* Address issues

* Update the gorram license header

* Dear lord

Source/ASCellNode.h

@@ -117,6 +117,15 @@ typedef NS_ENUM(NSUInteger, ASCellNodeVisibilityEvent) {
  */
 @property (atomic, readonly, nullable) NSIndexPath *indexPath;
 
+/**
+ * BETA: API is under development. We will attempt to provide an easy migration pathway for any changes.
+ *
+ * The view-model currently assigned to this node, if any.
+ *
+ * This property may be set off the main thread, but this method will never be invoked concurrently on the 
+ */
+@property (atomic, nullable) id viewModel;
+
 /**
  * The backing view controller, or @c nil if the node wasn't initialized with backing view controller
  * @note This property must be accessed on the main thread.

Source/ASCollectionNode.h

@@ -418,6 +418,17 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (nullable __kindof ASCellNode *)nodeForItemAtIndexPath:(NSIndexPath *)indexPath AS_WARN_UNUSED_RESULT;
 
+/**
+ * Retrieves the view-model for the item at the given index path, if any.
+ *
+ * @param indexPath The index path of the requested item.
+ *
+ * @return The view-model for the given item, or @c nil if no item exists at the specified path or no view-model was provided.
+ *
+ * @warning This API is beta and subject to change. We'll try to provide an easy migration path.
+ */
+- (nullable id)viewModelForItemAtIndexPath:(NSIndexPath *)indexPath AS_WARN_UNUSED_RESULT;
+
 /**
  * Retrieve the index path for the item with the given node.
  *
@@ -503,6 +514,17 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (NSInteger)numberOfSectionsInCollectionNode:(ASCollectionNode *)collectionNode;
 
+/**
+ * --BETA--
+ * Asks the data source for a view-model for the item at the given index path.
+ *
+ * @param collectionNode The sender.
+ * @param indexPath The index path of the item.
+ *
+ * @return An object that contains all the data for this item.
+ */
+- (nullable id)collectionNode:(ASCollectionNode *)collectionNode viewModelForItemAtIndexPath:(NSIndexPath *)indexPath;
+
 /**
  * Similar to -collectionNode:nodeForItemAtIndexPath:
  * This method takes precedence over collectionNode:nodeForItemAtIndexPath: if implemented.

Source/ASCollectionNode.mm

@@ -590,6 +590,12 @@
   return [self.dataController.pendingMap elementForItemAtIndexPath:indexPath].node;
 }
 
+- (id)viewModelForItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  [self reloadDataInitiallyIfNeeded];
+  return [self.dataController.pendingMap elementForItemAtIndexPath:indexPath].viewModel;
+}
+
 - (NSIndexPath *)indexPathForNode:(ASCellNode *)cellNode
 {
   return [self.dataController.pendingMap indexPathForElement:cellNode.collectionElement];

Source/ASCollectionView.mm

@@ -207,6 +207,7 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
     unsigned int collectionViewNumberOfItemsInSection:1;
     unsigned int collectionNodeNodeForItem:1;
     unsigned int collectionNodeNodeBlockForItem:1;
+    unsigned int viewModelForItem:1;
     unsigned int collectionNodeNodeForSupplementaryElement:1;
     unsigned int collectionNodeNodeBlockForSupplementaryElement:1;
     unsigned int collectionNodeSupplementaryElementKindsInSection:1;
@@ -450,6 +451,7 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
     _asyncDataSourceFlags.collectionNodeNodeForSupplementaryElement = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeForSupplementaryElementOfKind:atIndexPath:)];
     _asyncDataSourceFlags.collectionNodeNodeBlockForSupplementaryElement = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeBlockForSupplementaryElementOfKind:atIndexPath:)];
     _asyncDataSourceFlags.collectionNodeSupplementaryElementKindsInSection = [_asyncDataSource respondsToSelector:@selector(collectionNode:supplementaryElementKindsInSection:)];
+    _asyncDataSourceFlags.viewModelForItem = [_asyncDataSource respondsToSelector:@selector(collectionNode:viewModelForItemAtIndexPath:)];
 
     _asyncDataSourceFlags.interop = [_asyncDataSource conformsToProtocol:@protocol(ASCollectionDataSourceInterop)];
     if (_asyncDataSourceFlags.interop) {
@@ -1611,6 +1613,16 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
 
 #pragma mark - ASDataControllerSource
 
+- (id)dataController:(ASDataController *)dataController viewModelForItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  if (!_asyncDataSourceFlags.viewModelForItem) {
+    return nil;
+  }
+
+  GET_COLLECTIONNODE_OR_RETURN(collectionNode, nil);
+  return [_asyncDataSource collectionNode:collectionNode viewModelForItemAtIndexPath:indexPath];
+}
+
 - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAtIndexPath:(NSIndexPath *)indexPath
 {
   ASCellNodeBlock block = nil;

Source/ASTableView.mm

@@ -1629,6 +1629,12 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 #pragma mark - ASDataControllerSource
 
+- (id)dataController:(ASDataController *)dataController viewModelForItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  // Not currently supported for tables. Will be added when the collection API stabilizes.
+  return nil;
+}
+
 - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAtIndexPath:(NSIndexPath *)indexPath {
   ASCellNodeBlock block = nil;
 

Source/Details/ASCollectionElement.h

@@ -31,8 +31,10 @@ AS_SUBCLASSING_RESTRICTED
 @property (nonatomic, assign) ASSizeRange constrainedSize;
 @property (nonatomic, readonly, weak) id<ASRangeManagingNode> owningNode;
 @property (nonatomic, assign) ASPrimitiveTraitCollection traitCollection;
+@property (nonatomic, readonly, nullable) id viewModel;
 
-- (instancetype)initWithNodeBlock:(ASCellNodeBlock)nodeBlock
+- (instancetype)initWithViewModel:(nullable id)viewModel
+                        nodeBlock:(ASCellNodeBlock)nodeBlock
          supplementaryElementKind:(nullable NSString *)supplementaryElementKind
                   constrainedSize:(ASSizeRange)constrainedSize
                        owningNode:(id<ASRangeManagingNode>)owningNode

Source/Details/ASCollectionElement.mm

@@ -31,7 +31,8 @@
   ASCellNode *_node;
 }
 
-- (instancetype)initWithNodeBlock:(ASCellNodeBlock)nodeBlock
+- (instancetype)initWithViewModel:(id)viewModel
+                        nodeBlock:(ASCellNodeBlock)nodeBlock
          supplementaryElementKind:(NSString *)supplementaryElementKind
                   constrainedSize:(ASSizeRange)constrainedSize
                        owningNode:(id<ASRangeManagingNode>)owningNode
@@ -40,6 +41,7 @@
   NSAssert(nodeBlock != nil, @"Node block must not be nil");
   self = [super init];
   if (self) {
+    _viewModel = viewModel;
     _nodeBlock = nodeBlock;
     _supplementaryElementKind = [supplementaryElementKind copy];
     _constrainedSize = constrainedSize;
@@ -62,6 +64,7 @@
     node.owningNode = _owningNode;
     node.collectionElement = self;
     ASTraitCollectionPropagateDown(node, _traitCollection);
+    node.viewModel = _viewModel;
     _node = node;
   }
   return _node;

Source/Details/ASDataController.h

@@ -76,6 +76,8 @@ extern NSString * const ASCollectionInvalidUpdateException;
  */
 - (BOOL)dataController:(ASDataController *)dataController presentedSizeForElement:(ASCollectionElement *)element matchesSize:(CGSize)size;
 
+- (nullable id)dataController:(ASDataController *)dataController viewModelForItemAtIndexPath:(NSIndexPath *)indexPath;
+
 @optional
 
 /**

Source/Details/ASDataController.mm

@@ -384,6 +384,8 @@ typedef void (^ASDataControllerCompletionBlock)(NSArray<ASCollectionElement *> *
   id<ASDataControllerSource> dataSource = self.dataSource;
   id<ASRangeManagingNode> node = self.node;
   for (NSIndexPath *indexPath in indexPaths) {
+    id viewModel = [dataSource dataController:self viewModelForItemAtIndexPath:indexPath];
+
     ASCellNodeBlock nodeBlock;
     if (isRowKind) {
       nodeBlock = [dataSource dataController:self nodeBlockAtIndexPath:indexPath];
@@ -396,7 +398,8 @@ typedef void (^ASDataControllerCompletionBlock)(NSArray<ASCollectionElement *> *
       constrainedSize = [self constrainedSizeForNodeOfKind:kind atIndexPath:indexPath];
     }
     
-    ASCollectionElement *element = [[ASCollectionElement alloc] initWithNodeBlock:nodeBlock
+    ASCollectionElement *element = [[ASCollectionElement alloc] initWithViewModel:viewModel
+                                                                        nodeBlock:nodeBlock
                                                          supplementaryElementKind:isRowKind ? nil : kind
                                                                   constrainedSize:constrainedSize
                                                                        owningNode:node

Tests/ASCollectionModernDataSourceTests.m

@@ -27,10 +27,15 @@
   UIWindow *window;
   UIViewController *viewController;
   ASCollectionNode *collectionNode;
+  NSMutableArray<NSMutableArray *> *sections;
 }
 
 - (void)setUp {
   [super setUp];
+  // Default is 2 sections: 2 items in first, 1 item in second.
+  sections = [NSMutableArray array];
+  [sections addObject:[NSMutableArray arrayWithObjects:[NSObject new], [NSObject new], nil]];
+  [sections addObject:[NSMutableArray arrayWithObjects:[NSObject new], nil]];
   window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
   viewController = [[UIViewController alloc] init];
 
@@ -46,6 +51,7 @@
    @selector(numberOfSectionsInCollectionNode:),
    @selector(collectionNode:numberOfItemsInSection:),
    @selector(collectionNode:nodeBlockForItemAtIndexPath:),
+   @selector(collectionNode:viewModelForItemAtIndexPath:),
    nil];
   [mockDataSource setExpectationOrderMatters:YES];
   
@@ -59,48 +65,138 @@
   [super tearDown];
 }
 
-- (void)testInitialDataLoadingCallPattern
+#pragma mark - Test Methods
+
+- (void)testInitialDataLoading
 {
-  /// BUG: these methods are called twice in a row i.e. this for-loop shouldn't be here. https://github.com/TextureGroup/Texture/issues/351
-  for (int i = 0; i < 2; i++) {
-    NSArray *counts = @[ @2 ];
-    [self expectDataSourceMethodsWithCounts:counts];
-  }
-  
-  [window layoutIfNeeded];
+  [self loadInitialData];
+}
+
+- (void)testReloadingAnItem
+{
+  [self loadInitialData];
+
+  // Reload at (0, 0)
+  NSIndexPath *reloadedPath = [NSIndexPath indexPathForItem:0 inSection:0];
+
+  sections[reloadedPath.section][reloadedPath.item] = [NSObject new];
+  [self performUpdateInvalidatingItems:@[ reloadedPath ] block:^{
+    [collectionNode reloadItemsAtIndexPaths:@[ reloadedPath ]];
+  }];
+}
+
+- (void)testInsertingAnItem
+{
+  [self loadInitialData];
+
+  // Insert at (1, 0)
+  NSIndexPath *insertedPath = [NSIndexPath indexPathForItem:0 inSection:1];
+
+  [sections[insertedPath.section] insertObject:[NSObject new] atIndex:insertedPath.item];
+  [self performUpdateInvalidatingItems:@[ insertedPath ] block:^{
+    [collectionNode insertItemsAtIndexPaths:@[ insertedPath ]];
+  }];
 }
 
 #pragma mark - Helpers
 
+- (void)loadInitialData
+{
+  /// BUG: these methods are called twice in a row i.e. this for-loop shouldn't be here. https://github.com/TextureGroup/Texture/issues/351
+  for (int i = 0; i < 2; i++) {
+    // It reads all the counts
+    [self expectDataSourceCountMethods];
+
+    // It reads the contents for each item.
+    for (NSInteger section = 0; section < sections.count; section++) {
+      NSArray *items = sections[section];
+
+      // For each item:
+      for (NSInteger i = 0; i < items.count; i++) {
+        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:section];
+        [self expectContentMethodsForItemAtIndexPath:indexPath];
+      }
+    }
+  }
+
+  [window layoutIfNeeded];
+
+  // Assert item counts & content:
+  [self assertCollectionNodeContent];
+}
+
 /**
  * Adds expectations for the sequence:
  *
  * numberOfSectionsInCollectionNode:
  * for section in countsArray
  *  numberOfItemsInSection:
- *  for item < itemCount
- *    nodeBlockForItemAtIndexPath:
  */
-- (void)expectDataSourceMethodsWithCounts:(NSArray<NSNumber *> *)counts
+- (void)expectDataSourceCountMethods
 {
   // -numberOfSectionsInCollectionNode
   OCMExpect([mockDataSource numberOfSectionsInCollectionNode:collectionNode])
-  .andReturn(counts.count);
+  .andReturn(sections.count);
   
   // For each section:
   // Note: Skip fast enumeration for readability.
-  for (NSInteger section = 0; section < counts.count; section++) {
-    NSInteger itemCount = counts[section].integerValue;
+  for (NSInteger section = 0; section < sections.count; section++) {
+    NSInteger itemCount = sections[section].count;
     OCMExpect([mockDataSource collectionNode:collectionNode numberOfItemsInSection:section])
     .andReturn(itemCount);
-    
-    // For each item:
-    for (NSInteger i = 0; i < itemCount; i++) {
-      NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:section];
-      OCMExpect([mockDataSource collectionNode:collectionNode nodeBlockForItemAtIndexPath:indexPath])
-      .andReturn((ASCellNodeBlock)^{ return [[ASCellNode alloc] init]; });
+  }
+}
+
+// Expects viewModelForItemAtIndexPath: and nodeBlockForItemAtIndexPath:
+- (void)expectContentMethodsForItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  id viewModel = sections[indexPath.section][indexPath.item];
+  OCMExpect([mockDataSource collectionNode:collectionNode viewModelForItemAtIndexPath:indexPath])
+  .andReturn(viewModel);
+  OCMExpect([mockDataSource collectionNode:collectionNode nodeBlockForItemAtIndexPath:indexPath])
+  .andReturn((ASCellNodeBlock)^{ return [ASCellNode new]; });
+}
+
+- (void)assertCollectionNodeContent
+{
+  // Assert section count
+  XCTAssertEqual(collectionNode.numberOfSections, sections.count);
+
+  for (NSInteger section = 0; section < sections.count; section++) {
+    NSArray *items = sections[section];
+    // Assert item count
+    XCTAssertEqual([collectionNode numberOfItemsInSection:section], items.count);
+    for (NSInteger item = 0; item < items.count; item++) {
+      // Assert view model
+      // Could use pointer equality but the error message is less readable.
+      NSIndexPath *indexPath = [NSIndexPath indexPathForItem:item inSection:section];
+      id viewModel = sections[indexPath.section][indexPath.item];
+      XCTAssertEqualObjects(viewModel, [collectionNode viewModelForItemAtIndexPath:indexPath]);
+      ASCellNode *node = [collectionNode nodeForItemAtIndexPath:indexPath];
+      XCTAssertEqualObjects(node.viewModel, viewModel);
     }
   }
 }
 
+/**
+ * Updates the collection node, with expectations and assertions about the call-order and the correctness of the
+ * new data. You should update the data source _before_ calling this method.
+ *
+ * invalidatedIndexPaths are the items we expect to get refetched (reloaded/inserted).
+ */
+- (void)performUpdateInvalidatingItems:(NSArray<NSIndexPath *> *)invalidatedIndexPaths block:(void(^)())update
+{
+  // When we do an edit, it'll read the new counts
+  [self expectDataSourceCountMethods];
+
+  // Then it'll load the contents for inserted/reloaded items.
+  for (NSIndexPath *indexPath in invalidatedIndexPaths) {
+    [self expectContentMethodsForItemAtIndexPath:indexPath];
+  }
+
+  [collectionNode performBatchUpdates:update completion:nil];
+
+  [self assertCollectionNodeContent];
+}
+
 @end

examples/CatDealsCollectionView/Sample/ItemNode.h

@@ -1,18 +1,18 @@
 //
 //  ItemNode.h
-//  Sample
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
+//  Pinterest, 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
 //
 
 #import <AsyncDisplayKit/AsyncDisplayKit.h>

examples/CatDealsCollectionView/Sample/ItemNode.m

@@ -1,18 +1,18 @@
 //
 //  ItemNode.m
-//  Sample
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
+//  Pinterest, 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
 //
 
 #import "ItemNode.h"
@@ -50,7 +50,7 @@ const CGFloat kSoldOutGBHeight = 50.0;
 {
   self = [super init];
   if (self != nil) {
-    _viewModel = viewModel;
+    self.viewModel = viewModel;
     [self setup];
     [self updateLabels];
     [self updateBackgroundColor];