OOWeakSet.m

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/*
 
OOWeakSet.m
 
Written by Jens Ayton in 2012 for Oolite.
This code is hereby placed in the public domain.
 
*/
 
#import "OOWeakSet.h"
 
 
 
@interface OOWeakRefUnpackingEnumerator: NSEnumerator
{
@private
    NSEnumerator            *_enumerator;
}
 
- (id) initWithEnumerator:(NSEnumerator *)enumerator;
 
+ (instancetype) enumeratorWithCollection:(id)collection;   // Collection must implement -objectEnumerator
 
@end
 
 
@interface OOWeakSet (OOPrivate)
 
- (void) compact;   // Remove any zeroed entries.
 
@end
 
 
@implementation OOWeakSet
 
- (id) init
{
    return [self initWithCapacity:0];
}
 
 
- (id) initWithCapacity:(NSUInteger)capacity
{
    if ((self = [super init]))
    {
        _objects = [[NSMutableSet alloc] initWithCapacity:capacity];
        if (_objects == NULL)
        {
            [self release];
            return nil;
        }
    }
    return self;
}
 
 
+ (instancetype) set
{
    return [[[self alloc] init] autorelease];
}
 
 
+ (instancetype) setWithCapacity:(NSUInteger)capacity
{
    return [[[self alloc] initWithCapacity:capacity] autorelease];
}
 
 
- (void) dealloc
{
    DESTROY(_objects);
    
    [super dealloc];
}
 
 
- (NSString *) description
{
    NSMutableString *result = [NSMutableString stringWithFormat:@"<%@ %p>{", [self class], self];
    NSEnumerator *selfEnum = [self objectEnumerator];
    id object = nil;
    BOOL first = YES;
    while ((object = [selfEnum nextObject]))
    {
        if (!first)  [result appendString:@", "];
        else  first = NO;
        
        NSString *desc = nil;
        if ([object respondsToSelector:@selector(shortDescription)])  desc = [object shortDescription];
        else  desc = [object description];
        
        [result appendString:desc];
    }
    
    [result appendString:@"}"];
    return result;
}
 
 
// MARK: Protocol conformance
 
- (id) copyWithZone:(NSZone *)zone
{
    [self compact];
    OOWeakSet *result = [[OOWeakSet allocWithZone:zone] init];
    [result addObjectsByEnumerating:[self objectEnumerator]];
    return result;
}
 
 
- (id) mutableCopyWithZone:(NSZone *)zone
{
    return [self copyWithZone:zone];
}
 
 
- (BOOL) isEqual:(id)other
{
    if (![other isKindOfClass:[OOWeakSet class]])  return NO;
    if ([self count] != [other count])  return NO;
    
    BOOL result = YES;
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSEnumerator *selfEnum = [self objectEnumerator];
    id object = nil;
    while ((object = [selfEnum nextObject]))
    {
        if (![other containsObject:object])
        {
            result = NO;
            break;
        }
    }
    DESTROY(pool);
    
    return result;
}
 
 
// MARK: Meat and potatoes
 
- (NSUInteger) count
{
    [self compact];
    return [_objects count];
}
 
 
- (BOOL) containsObject:(id<OOWeakReferenceSupport>)object
{
    [self compact];
    OOWeakReference *weakObj = [object weakRetain];
    BOOL result = [_objects containsObject:weakObj];
    [weakObj release];
    return result;
}
 
 
- (NSEnumerator *) objectEnumerator
{
    return [OOWeakRefUnpackingEnumerator enumeratorWithCollection:_objects];
}
 
 
- (void) addObject:(id<OOWeakReferenceSupport>)object
{
    if (object == nil)  return;
    NSAssert([object conformsToProtocol:@protocol(OOWeakReferenceSupport)], @"Attempt to add object to OOWeakSet which does not conform to OOWeakReferenceSupport.");
    
    OOWeakReference *weakObj = [object weakRetain];
    [_objects addObject:weakObj];
    [weakObj release];
}
 
 
- (void) removeObject:(id<OOWeakReferenceSupport>)object
{
    OOWeakReference *weakObj = [object weakRetain];
    [_objects removeObject:weakObj];
    [weakObj release];
}
 
 
- (void) addObjectsByEnumerating:(NSEnumerator *)enumerator
{
    id object = nil;
    [self compact];
    while ((object = [enumerator nextObject]))
    {
        [self addObject:object];
    }
}
 
 
- (void) makeObjectsPerformSelector:(SEL)selector
{
    OOWeakReference *weakRef = nil;
    foreach (weakRef, _objects)
    {
        [[weakRef weakRefUnderlyingObject] performSelector:selector];
    }
}
 
 
- (void) makeObjectsPerformSelector:(SEL)selector withObject:(id)argument
{
    OOWeakReference *weakRef = nil;
    foreach (weakRef, _objects)
    {
        [[weakRef weakRefUnderlyingObject] performSelector:selector withObject:argument];
    }
}
 
 
- (NSArray *) allObjects
{
    NSMutableArray *result = [NSMutableArray arrayWithCapacity:[_objects count]];
    OOWeakReference *weakRef = nil;
    foreach (weakRef, _objects)
    {
        id object = [weakRef weakRefUnderlyingObject];
        if (object != nil)  [result addObject:object];
    }
    
#ifdef NDEBUG
    return result;
#else
    return [NSArray arrayWithArray:result];
#endif
}
 
 
- (void) removeAllObjects
{
    [_objects removeAllObjects];
}
 
 
- (void) compact
{
    OOWeakReference *weakRef = nil;
    BOOL compactRequired = NO;
    foreach (weakRef, _objects)
    {
        if ([weakRef weakRefUnderlyingObject] == nil)
        {
            compactRequired = YES;
            break;
        }
    }
    
    if (compactRequired)
    {
        NSMutableSet *newObjects = [[NSMutableSet alloc] initWithCapacity:[_objects count]];
        foreach (weakRef, _objects)
        {
            if ([weakRef weakRefUnderlyingObject] != nil)
            {
                [newObjects addObject:weakRef];
            }
        }
        
        [_objects release];
        _objects = newObjects;
    }
}
 
@end
 
 
@implementation OOWeakRefUnpackingEnumerator
 
- (id) initWithEnumerator:(NSEnumerator *)enumerator
{
    if (enumerator == nil)
    {
        [self release];
        return nil;
    }
    
    if ((self = [super init]))
    {
        _enumerator = [enumerator retain];
    }
    
    return self;
}
 
 
+ (instancetype) enumeratorWithCollection:(id)collection
{
    return [[[self alloc] initWithEnumerator:[collection objectEnumerator]] autorelease];
}
 
 
- (void) dealloc
{
    [_enumerator release];
    
    [super dealloc];
}
 
 
- (id) nextObject
{
    id next = nil;
    while ((next = [_enumerator nextObject]))
    {
        next = [next weakRefUnderlyingObject];
        if (next != nil)  return next;
    }
    
    return nil;
}
 
@end