- Added cycle detection support

- To run a cycle detection on strong (non-transient) relationships, include the following tag into the template:
<$checkNonTransientRelationshipCycles $>
- This will cause mogenerator to exit with failure status if cycles are found.

contributed templates/Nikita Zhuk/ponso/templates/machine.h.motemplate

@@ -10,7 +10,7 @@
 
 #import <Foundation/Foundation.h>
 #import "ModelObject.h"
-
+<$checkNonTransientRelationshipCycles $>
 <$foreach Relationship noninheritedRelationships do$>@class <$Relationship.destinationEntity.managedObjectClassName$>;
 <$endforeach do$>
 

ponso/MKCNSEntityDescriptionAdditions.h

@@ -25,4 +25,8 @@
 /** @TypeInfo NSAttributeDescription */
 @property(nonatomic, readonly) NSArray *noninheritedRelationshipsInIDKeyPathTopologicalOrder;
 
+// Checks if the managed object model of the receiver contains cycles in non-transient relationships.
+// If cycles are found, an exception is raised.
+- (void)checkNonTransientRelationshipCycles;
+
 @end

ponso/MKCNSEntityDescriptionAdditions.m

@@ -38,6 +38,22 @@ - (BOOL)includeRelationship:(NSRelationshipDescription *)relationship
 
 @end
 
+@interface MKCNSRelationshipDescriptionNonTransientDependencyFilter : NSObject <MKCNSRelationshipDescriptionDependencyFilter> @end
+@implementation MKCNSRelationshipDescriptionNonTransientDependencyFilter
+
+- (BOOL)includeRelationship:(NSRelationshipDescription *)relationship
+{
+	if([[relationship entity] isEqual:[relationship destinationEntity]])
+		return NO;
+
+    if([relationship isTransient])
+        return NO;
+
+    return YES;
+}
+
+@end
+
 @implementation NSEntityDescription(MKCNSEntityDescriptionAdditions)
 
 /** @TypeInfo NSAttributeDescription */
@@ -80,4 +96,17 @@ - (NSArray*)noninheritedRelationshipsInIDKeyPathTopologicalOrder
 	return sortedRelationships;
 }
 
+- (void)checkNonTransientRelationshipCycles
+{
+    id dependencyFilter = [[[MKCNSRelationshipDescriptionNonTransientDependencyFilter alloc] init] autorelease];
+    NSArray *entities = [[self managedObjectModel] entitiesInTopologicalOrderUsingDependencyFilter:dependencyFilter];
+
+    if(entities == nil)
+    {
+        NSString *desc = @"Cycles were found in non-transient relationships.";
+
+        [[NSException exceptionWithName:@"StrongRelationshipCyclesFoundException" reason:desc userInfo:nil] raise];
+    }
+}
+
 @end