Merge remote-tracking branch 'origin/PROViewModelParentAndRootPropert…

…ies'

Proton/PROViewModel.h

@@ -96,6 +96,26 @@ typedef enum {
  */
 @property (nonatomic, strong) id model;
 
+/**
+ * Parent View Models
+ */
+
+/**
+ * The immediate parent view model of the receiver. Returns `nil` if the
+ * receiver is the <rootViewModel> for its hierarchy.
+ *
+ * This property is `nil` by default.
+ */
+@property (nonatomic, weak) PROViewModel *parentViewModel;
+
+/**
+ * The root view model of the receiver.
+ *
+ * Returns the <[PROViewModel rootViewModel]> of the receiver's <parentViewModel>
+ * or the receiver if it has no parent.
+ */
+@property (nonatomic, weak, readonly) PROViewModel *rootViewModel;
+
 /**
  * @name Declared Properties
  */
@@ -135,7 +155,7 @@ typedef enum {
 /**
  * Returns whether the given action selector can be validly invoked, given the
  * current state of the receiver.
- * 
+ *
  * The default implementation of this method looks for a method named
  * `-validate<Action>` on the receiver, invoking it and using its result if
  * present. Subclasses that override this method to perform custom logic should

Proton/PROViewModel.m

@@ -41,6 +41,7 @@ @implementation PROViewModel
 @synthesize model = m_model;
 @synthesize observationInfo = m_observationInfo;
 @synthesize initializingFromArchive = m_initializingFromArchive;
+@synthesize parentViewModel = m_parentViewModel;
 
 - (void)setModel:(id)model {
     if (model == m_model)
@@ -52,6 +53,13 @@ - (void)setModel:(id)model {
     m_model = model;
 }
 
+- (PROViewModel *)rootViewModel {
+    if (!self.parentViewModel)
+        return self;
+
+    return self.parentViewModel.rootViewModel;
+}
+
 #pragma mark - Lifecycle
 
 - (id)init; {
@@ -196,15 +204,15 @@ - (id)initWithCoder:(NSCoder *)coder {
 
     [self.class enumeratePropertiesUsingBlock:^(objc_property_t property, NSString *key){
         id value = [coder decodeObjectForKey:key];
-        
+
         if (!value) {
             PROAssert([self.class encodingBehaviorForKey:key] != PROViewModelEncodingBehaviorUnconditional, @"Key \"%@\" of %@ should have been unconditionally encoded, but is not present in the archive", key, self.class);
             return;
         }
 
         if ([value isEqual:[NSNull null]])
             value = nil;
-        
+
         [self setValue:value forKey:key];
     }];
 

ProtonTests/PROViewModelTests.m

@@ -77,6 +77,8 @@ - (BOOL)validateSomeAction;
             expect(viewModel.date).toBeNil();
             expect(viewModel.enabled).toBeFalsy();
             expect(viewModel.initializingFromArchive).toBeFalsy();
+            expect(viewModel.parentViewModel).toBeNil();
+            expect(viewModel.rootViewModel).toEqual(viewModel);
         });
 
         describe(@"with an instance", ^{
@@ -105,6 +107,29 @@ - (BOOL)validateSomeAction;
                 expect(viewModel).not.toEqual(otherViewModel);
             });
 
+            describe(@"with parent view models", ^{
+                __block PROViewModel *parentViewModel;
+
+                before(^{
+                    parentViewModel = [[PROViewModel alloc] init];
+                    expect(parentViewModel).not.toBeNil();
+
+                    viewModel.parentViewModel = parentViewModel;
+                    expect(viewModel.parentViewModel).toEqual(parentViewModel);
+                });
+
+                it(@"returns its parentViewModel as its rootViewModel when its parentViewModel has no ancestors", ^{
+                    expect(viewModel.rootViewModel).toEqual(parentViewModel);
+                });
+
+                it(@"returns its ancestor parentViewModel as its rootViewModel", ^{
+                    PROViewModel *grandParentViewModel = [[PROViewModel alloc] init];
+                    parentViewModel.parentViewModel = grandParentViewModel;
+
+                    expect(viewModel.rootViewModel).toEqual(grandParentViewModel);
+                });
+            });
+
             describe(@"archiving behavior", ^{
                 __block id unretainedObject = nil;
 
@@ -140,7 +165,7 @@ - (BOOL)validateSomeAction;
 
                     NSMutableData *encoded = [NSMutableData data];
                     NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:encoded];
-                    
+
                     [archiver encodeObject:unretainedObject forKey:@"unretainedObject"];
                     [archiver encodeObject:viewModel forKey:@"viewModel"];