Swiftgram/submodules/AsyncDisplayKit/Source/ASCollectionLayoutCache.mm
2019-11-11 16:39:27 +04:00

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//
// ASCollectionLayoutCache.mm
// Texture
//
// Copyright (c) Pinterest, Inc. All rights reserved.
// Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
//
#ifndef MINIMAL_ASDK
#import <AsyncDisplayKit/ASCollectionLayoutCache.h>
#import <AsyncDisplayKit/ASCollectionLayoutContext.h>
#import <AsyncDisplayKit/ASCollectionLayoutState.h>
#import <AsyncDisplayKit/ASElementMap.h>
#import <AsyncDisplayKit/ASThread.h>
using AS::MutexLocker;
@implementation ASCollectionLayoutCache {
AS::Mutex __instanceLock__;
/**
* The underlying data structure of this cache.
*
* The outer map table is a weak to strong table. That is because ASCollectionLayoutContext doesn't (and shouldn't)
* hold a strong reference on its element map. As a result, this cache should handle the case in which
* an element map no longer exists and all contexts and layouts associated with it should be cleared.
*
* The inner map table is a standard strong to strong map.
* Since different ASCollectionLayoutContext objects with the same content are considered equal,
* "object pointer personality" can't be used as a key option.
*/
NSMapTable<ASElementMap *, NSMapTable<ASCollectionLayoutContext *, ASCollectionLayoutState *> *> *_map;
}
- (instancetype)init
{
self = [super init];
if (self) {
_map = [NSMapTable mapTableWithKeyOptions:(NSMapTableWeakMemory | NSMapTableObjectPointerPersonality) valueOptions:NSMapTableStrongMemory];
}
return self;
}
- (ASCollectionLayoutState *)layoutForContext:(ASCollectionLayoutContext *)context
{
ASElementMap *elements = context.elements;
if (elements == nil) {
return nil;
}
MutexLocker l(__instanceLock__);
return [[_map objectForKey:elements] objectForKey:context];
}
- (void)setLayout:(ASCollectionLayoutState *)layout forContext:(ASCollectionLayoutContext *)context
{
ASElementMap *elements = context.elements;
if (layout == nil || elements == nil) {
return;
}
MutexLocker l(__instanceLock__);
auto innerMap = [_map objectForKey:elements];
if (innerMap == nil) {
innerMap = [NSMapTable strongToStrongObjectsMapTable];
[_map setObject:innerMap forKey:elements];
}
[innerMap setObject:layout forKey:context];
}
- (void)removeLayoutForContext:(ASCollectionLayoutContext *)context
{
ASElementMap *elements = context.elements;
if (elements == nil) {
return;
}
MutexLocker l(__instanceLock__);
[[_map objectForKey:elements] removeObjectForKey:context];
}
- (void)removeAllLayouts
{
MutexLocker l(__instanceLock__);
[_map removeAllObjects];
}
@end
#endif