kylefang/RestKit
1
0
Fork 0
mirror of https://github.com/zhigang1992/RestKit.git synced 2026-05-04 10:11:30 +08:00
Code Issues Packages Projects Releases Wiki Activity

Implement Tarjan's algorithm to efficiently traverse the RKResponseDescriptors within the RKManagedObjectRequestOperation and compute the key paths to all managed objects. refs #1113, refs #1112

Browse Source
This commit is contained in:
Blake Watters
2012-12-28 00:29:27 -05:00
parent 5c21e52829
commit 84c6822d25
2 changed files with 89 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

84
Code/Network/RKManagedObjectRequestOperation.m
View File

@@ -35,16 +35,27 @@
#undef RKLogComponent
#define RKLogComponent RKlcl_cRestKitCoreData
/**
This class implements Tarjan's algorithm to efficiently visit all nodes within the mapping graph and detect cycles in the graph.
For more details on the algorithm, refer to the Wikipedia page: http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
The following reference implementations were used when building out an Objective-C implementation:
1. http://algowiki.net/wiki/index.php?title=Tarjan%27s_algorithm
1. http://www.logarithmic.net/pfh-files/blog/01208083168/sort.py
*/
@interface RKNestedManagedObjectKeyPathMappingGraphVisitor : NSObject
@property (nonatomic, readonly) NSSet *keyPaths;
- (id)initWithResponseDescriptors:(NSArray *)responseDescriptors;
@end
@interface RKNestedManagedObjectKeyPathMappingGraphVisitor ()
@property (nonatomic, strong) NSMutableSet *mutableKeyPaths;
@property (nonatomic, strong) NSMutableArray *visitationStack;
@property (nonatomic, strong) NSMutableDictionary *lowValues;
@property (nonatomic, strong) NSNumber *numberOfDecriptors;
@end
@implementation RKNestedManagedObjectKeyPathMappingGraphVisitor
@@ -53,7 +64,11 @@
{
self = [self init];
if (self) {
self.numberOfDecriptors = @([responseDescriptors count]);
self.mutableKeyPaths = [NSMutableSet set];
self.visitationStack = [NSMutableArray array];
self.lowValues = [NSMutableDictionary dictionary];
for (RKResponseDescriptor *responseDescriptor in responseDescriptors) {
[self visitMapping:responseDescriptor.mapping atKeyPath:responseDescriptor.keyPath];
}
@@ -61,28 +76,63 @@
return self;
}
- (NSSet *)keyPaths
{
return self.mutableKeyPaths;
}
// Traverse the mappings graph using Tarjan's algorithm
- (void)visitMapping:(RKMapping *)mapping atKeyPath:(NSString *)keyPath
{
id actualKeyPath = keyPath ?: [NSNull null];
if ([self.keyPaths containsObject:actualKeyPath]) return;
if ([mapping isKindOfClass:[RKEntityMapping class]]) [self.mutableKeyPaths addObject:actualKeyPath];
if ([mapping isKindOfClass:[RKDynamicMapping class]]) {
RKDynamicMapping *dynamicMapping = (RKDynamicMapping *)mapping;
for (RKMapping *nestedMapping in dynamicMapping.objectMappings) {
[self visitMapping:nestedMapping atKeyPath:keyPath];
}
} else if ([mapping isKindOfClass:[RKObjectMapping class]]) {
NSValue *dictionaryKey = [NSValue valueWithNonretainedObject:mapping];
if ([self.lowValues objectForKey:dictionaryKey]) {
// This key path points to a cycle back into the graph
if ([mapping isKindOfClass:[RKEntityMapping class]]) [self.mutableKeyPaths addObject:keyPath];
return;
}
NSNumber *lowValue = @([self.lowValues count]);
[self.lowValues setObject:lowValue forKey:dictionaryKey];
NSUInteger stackPosition = [self.visitationStack count];
[self.visitationStack addObject:@{ @"mapping": mapping, @"keyPath": keyPath ?: [NSNull null] }];
if ([mapping isKindOfClass:[RKObjectMapping class]]) {
RKObjectMapping *objectMapping = (RKObjectMapping *)mapping;
for (RKRelationshipMapping *relationshipMapping in objectMapping.relationshipMappings) {
NSString *nestedKeyPath = keyPath ? [@[ keyPath, relationshipMapping.destinationKeyPath ] componentsJoinedByString:@"."] : relationshipMapping.destinationKeyPath;
[self visitMapping:relationshipMapping.mapping atKeyPath:nestedKeyPath];
// We want the minimum value
NSValue *relationshipKey = [NSValue valueWithNonretainedObject:relationshipMapping.mapping];
NSNumber *relationshipLowValue = [self.lowValues objectForKey:relationshipKey];
if ([lowValue compare:relationshipLowValue] == NSOrderedDescending) {
[self.lowValues setObject:relationshipLowValue forKey:dictionaryKey];
}
}
} else if ([mapping isKindOfClass:[RKDynamicMapping class]]) {
RKDynamicMapping *dynamicMapping = (RKDynamicMapping *)mapping;
for (RKMapping *nestedMapping in dynamicMapping.objectMappings) {
[self visitMapping:nestedMapping atKeyPath:keyPath];
}
}
if ([[self.lowValues objectForKey:dictionaryKey] isEqualToNumber:lowValue]) {
NSRange range = NSMakeRange(stackPosition, [self.visitationStack count] - stackPosition);
NSArray *mappingDetails = [self.visitationStack subarrayWithRange:range];
[self.visitationStack removeObjectsInRange:range];
NSArray *mappings = [mappingDetails valueForKey:@"mapping"];
for (NSDictionary *dictionary in mappingDetails) {
NSString *keyPath = [dictionary objectForKey:@"keyPath"];
NSString *mapping = [dictionary objectForKey:@"mapping"];
if ([mapping isKindOfClass:[RKEntityMapping class]]) [self.mutableKeyPaths addObject:keyPath];
}
for (RKMapping *mapping in mappings) {
NSValue *relationshipKey = [NSValue valueWithNonretainedObject:mapping];
[self.lowValues setObject:self.numberOfDecriptors forKey:relationshipKey];
}
}
}
- (NSSet *)keyPaths
{
return self.mutableKeyPaths;
}
@end