[Layout] Add extensibility support to ASLayoutElementStyle (#2975)

* Add extensibility support to ASLayoutElementStyle

* Fix some typo

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -588,6 +588,7 @@
 		698C8B601CAB49FC0052DC3F /* ASLayoutElementExtensibility.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = ASLayoutElementExtensibility.h; path = AsyncDisplayKit/Layout/ASLayoutElementExtensibility.h; sourceTree = "<group>"; };
 		698DFF431E36B6C9002891F1 /* ASStackLayoutSpecUtilities.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASStackLayoutSpecUtilities.h; sourceTree = "<group>"; };
 		698DFF461E36B7E9002891F1 /* ASLayoutSpecUtilities.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASLayoutSpecUtilities.h; sourceTree = "<group>"; };
+		699B83501E3C1BA500433FA4 /* ASLayoutSpecTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASLayoutSpecTests.m; sourceTree = "<group>"; };
 		69B225661D72535E00B25B22 /* ASDisplayNodeLayoutTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASDisplayNodeLayoutTests.mm; sourceTree = "<group>"; };
 		69B225681D7265DA00B25B22 /* ASXCTExtensions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASXCTExtensions.h; sourceTree = "<group>"; };
 		69CB62A91CB8165900024920 /* _ASDisplayViewAccessiblity.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = _ASDisplayViewAccessiblity.h; sourceTree = "<group>"; };
@@ -1020,6 +1021,7 @@
 				2538B6F21BC5D2A2003CA0B4 /* ASCollectionViewFlowLayoutInspectorTests.m */,
 				69FEE53C1D95A9AF0086F066 /* ASLayoutElementStyleTests.m */,
 				695BE2541DC1245C008E6EA5 /* ASWrapperSpecSnapshotTests.mm */,
+				699B83501E3C1BA500433FA4 /* ASLayoutSpecTests.m */,
 			);
 			name = Tests;
 			path = AsyncDisplayKitTests;
@@ -1763,6 +1765,7 @@
 				CCB2F34D1D63CCC6004E6DE9 /* ASDisplayNodeSnapshotTests.m in Sources */,
 				AE6987C11DD04E1000B9E458 /* ASPagerNodeTests.m in Sources */,
 				058D0A3A195D057000B7D73C /* ASDisplayNodeTests.m in Sources */,
+				699B83511E3C1BA500433FA4 /* ASLayoutSpecTests.m in Sources */,
 				696FCB311D6E46050093471E /* ASBackgroundLayoutSpecSnapshotTests.mm in Sources */,
 				69FEE53D1D95A9AF0086F066 /* ASLayoutElementStyleTests.m in Sources */,
 				CC4981B31D1A02BE004E13CC /* ASTableViewThrashTests.m in Sources */,

AsyncDisplayKit/Layout/ASLayoutElementExtensibility.h

@@ -16,6 +16,10 @@
 #import <Foundation/NSGeometry.h>
 #endif
 
+#import <objc/runtime.h>
+
+#pragma mark - ASLayoutElementExtensibility
+
 @protocol ASLayoutElementExtensibility <NSObject>
 
 // The maximum number of extended values per type are defined in ASEnvironment.h above the ASEnvironmentStateExtensions
@@ -30,5 +34,80 @@
 - (void)setLayoutOptionExtensionEdgeInsets:(UIEdgeInsets)value atIndex:(int)idx;
 - (UIEdgeInsets)layoutOptionExtensionEdgeInsetsAtIndex:(int)idx;
 
-
 @end
+
+#pragma mark - Dynamic Properties
+
+/**
+ * Unbox NSNumber based on the type
+ */
+#define ASDK_UNBOX_NUMBER(NUMBER, PROPERTY_TYPE) \
+const char *objCType = [NUMBER objCType]; \
+if (strcmp(objCType, @encode(BOOL)) == 0) { \
+  return (PROPERTY_TYPE)[obj boolValue]; \
+} else if (strcmp(objCType, @encode(int)) == 0) { \
+  return (PROPERTY_TYPE)[obj intValue]; \
+} else if (strcmp(objCType, @encode(NSInteger)) == 0) { \
+  return (PROPERTY_TYPE)[obj integerValue]; \
+} else if (strcmp(objCType, @encode(NSUInteger)) == 0) { \
+  return (PROPERTY_TYPE)[obj unsignedIntegerValue]; \
+} else if (strcmp(objCType, @encode(CGFloat)) == 0) { \
+  return (PROPERTY_TYPE)[obj floatValue]; \
+} else { \
+  NSAssert(NO, @"Data type not supported"); \
+} \
+
+/**
+ * Define a NSObject property
+ */
+#define ASDK_STYLE_PROP_OBJ(PROPERTY_TYPE, PROPERTY_NAME, SETTER_NAME) \
+@dynamic PROPERTY_NAME; \
+- (PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  return (PROPERTY_TYPE)objc_getAssociatedObject(self, @selector(PROPERTY_NAME)); \
+} \
+\
+- (void)SETTER_NAME:(PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  objc_setAssociatedObject(self, @selector(PROPERTY_NAME), PROPERTY_NAME, OBJC_ASSOCIATION_RETAIN); \
+} \
+
+/**
+ * Define an primitive property
+ */
+#define ASDK_STYLE_PROP_PRIM(PROPERTY_TYPE, PROPERTY_NAME, SETTER_NAME, DEFAULT_VALUE) \
+@dynamic PROPERTY_NAME; \
+- (PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  id obj = objc_getAssociatedObject(self, @selector(PROPERTY_NAME)); \
+  \
+  if (obj != nil) { \
+    ASDK_UNBOX_NUMBER(obj, PROPERTY_TYPE); \
+  } \
+  \
+  return DEFAULT_VALUE;\
+} \
+\
+- (void)SETTER_NAME:(PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  objc_setAssociatedObject(self, @selector(PROPERTY_NAME), @(PROPERTY_NAME), OBJC_ASSOCIATION_RETAIN); \
+} \
+
+/**
+ * Define an structure property
+ */
+#define ASDK_STYLE_PROP_STR(PROPERTY_TYPE, PROPERTY_NAME, SETTER_NAME, DEFAULT_STRUCT) \
+@dynamic PROPERTY_NAME; \
+- (PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  id obj = objc_getAssociatedObject(self, @selector(PROPERTY_NAME)); \
+  if (obj == nil) { \
+    return DEFAULT_STRUCT; \
+  } \
+  PROPERTY_TYPE PROPERTY_NAME; [obj getValue:&PROPERTY_NAME]; return PROPERTY_NAME; \
+} \
+\
+- (void)SETTER_NAME:(PROPERTY_TYPE)PROPERTY_NAME \
+{ \
+  objc_setAssociatedObject(self, @selector(PROPERTY_NAME), [NSValue value:&PROPERTY_NAME withObjCType:@encode(PROPERTY_TYPE)], OBJC_ASSOCIATION_RETAIN_NONATOMIC);\
+} \

AsyncDisplayKitTests/ASLayoutSpecTests.m

@@ -0,0 +1,111 @@
+//
+//  ASLayoutSpecTests.m
+//  AsyncDisplayKit
+//
+//  Created by Michael Schneider on 1/27/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+#import <AsyncDisplayKit/AsyncDisplayKit.h>
+#import <AsyncDisplayKit/ASLayoutElementExtensibility.h>
+
+#pragma mark - ASDKExtendedLayoutSpec
+
+/*
+ * Extend the ASDKExtendedLayoutElement
+ * It adds a
+ *  - primitive / CGFloat (extendedWidth)
+ *  - struct / ASDimension (extendedDimension)
+ *  - primitive / ASStackLayoutDirection (extendedDirection)
+ */
+@protocol ASDKExtendedLayoutElement <NSObject>
+@property (assign, nonatomic) CGFloat extendedWidth;
+@property (assign, nonatomic) ASDimension extendedDimension;
+@property (copy, nonatomic) NSString *extendedName;
+@end
+
+/*
+ * Let the ASLayoutElementStyle conform to the ASDKExtendedLayoutElement protocol and add properties implementation
+ */
+@interface ASLayoutElementStyle (ASDKExtendedLayoutElement) <ASDKExtendedLayoutElement>
+@end
+
+@implementation ASLayoutElementStyle (ASDKExtendedLayoutElement)
+ASDK_STYLE_PROP_PRIM(CGFloat, extendedWidth, setExtendedWidth, 0);
+ASDK_STYLE_PROP_STR(ASDimension, extendedDimension, setExtendedDimension, ASDimensionMake(ASDimensionUnitAuto, 0));
+ASDK_STYLE_PROP_OBJ(NSString *, extendedName, setExtendedName);
+@end
+
+/*
+ * As the ASLayoutableStyle conforms to the ASDKExtendedLayoutable protocol now, ASDKExtendedLayoutable properties
+ * can be accessed in ASDKExtendedLayoutSpec
+ */
+@interface ASDKExtendedLayoutSpec : ASLayoutSpec
+@end
+
+@implementation ASDKExtendedLayoutSpec
+
+- (void)doSetSomeStyleValuesToChildren
+{
+  for (id<ASLayoutElement> child in self.children) {
+    child.style.extendedWidth = 100;
+    child.style.extendedDimension = ASDimensionMake(100);
+    child.style.extendedName = @"ASDK";
+  }
+}
+
+- (void)doUseSomeStyleValuesFromChildren
+{
+  for (id<ASLayoutElement> child in self.children) {
+    __unused CGFloat extendedWidth = child.style.extendedWidth;
+    __unused ASDimension extendedDimension = child.style.extendedDimension;
+    __unused NSString *extendedName = child.style.extendedName;
+  }
+}
+
+@end
+
+
+#pragma mark - ASLayoutSpecTests
+
+@interface ASLayoutSpecTests : XCTestCase
+
+@end
+
+@implementation ASLayoutSpecTests
+
+- (void)testSetPrimitiveToExtendedStyle
+{
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.style.extendedWidth = 100;
+  XCTAssert(node.style.extendedWidth == 100, @"Primitive value should be set on extended style");
+}
+
+- (void)testSetStructToExtendedStyle
+{
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.style.extendedDimension = ASDimensionMake(100);
+  XCTAssertTrue(ASDimensionEqualToDimension(node.style.extendedDimension, ASDimensionMake(100)), @"Struct should be set on extended style");
+}
+
+- (void)testSetObjectToExtendedStyle
+{
+  NSString *extendedName = @"ASDK";
+  
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.style.extendedName = extendedName;
+  XCTAssertEqualObjects(node.style.extendedName, extendedName, @"Object should be set on extended style");
+}
+
+
+- (void)testUseOfExtendedStyleProperties
+{
+  ASDKExtendedLayoutSpec *extendedLayoutSpec = [ASDKExtendedLayoutSpec new];
+  extendedLayoutSpec.children = @[[[ASDisplayNode alloc] init], [[ASDisplayNode alloc] init]];
+  XCTAssertNoThrow([extendedLayoutSpec doSetSomeStyleValuesToChildren]);
+  XCTAssertNoThrow([extendedLayoutSpec doUseSomeStyleValuesFromChildren]);
+}
+
+@end