| // Copyright 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef IOS_CHROME_BROWSER_SNAPSHOTS_LRU_CACHE_H_ |
| #define IOS_CHROME_BROWSER_SNAPSHOTS_LRU_CACHE_H_ |
| |
| #import <Foundation/Foundation.h> |
| |
| // This class implements a cache with a limited size. Once the cache reach its |
| // size limit, it will start to evict items in a Least Recently Used order |
| // (where the term "used" is determined in terms of query to the cache). |
| @interface LRUCache : NSObject |
| |
| // The maximum amount of items that the cache can hold before starting to |
| // evict. The value 0 is used to signify that the cache can hold an unlimited |
| // amount of elements (i.e. never evicts). |
| @property(nonatomic, readonly) NSUInteger maxCacheSize; |
| |
| // Use the initWithCacheSize: designated initializer. The is no good general |
| // default value for the cache size. |
| - (instancetype)init NS_UNAVAILABLE; |
| |
| // |maxCacheSize| value is used to specify the maximum amount of items that the |
| // cache can hold before starting to evict items. |
| - (instancetype)initWithCacheSize:(NSUInteger)maxCacheSize |
| NS_DESIGNATED_INITIALIZER; |
| |
| // Query the cache for an item corresponding to the |key|. Returns nil if there |
| // is no item corresponding to that key. |
| - (id)objectForKey:(id<NSObject>)key; |
| |
| // Adds the pair |key|, |obj| to the cache. If the value of the maxCacheSize |
| // property is non zero, the cache may evict an elements if the maximum cache |
| // size is reached. If the |key| is already present in the cache, the value for |
| // that key is replaced by |object|. |
| - (void)setObject:(id<NSObject>)object forKey:(NSObject*)key; |
| |
| // Remove the key, value pair corresponding to the given |key|. |
| - (void)removeObjectForKey:(id<NSObject>)key; |
| |
| // Remove all objects from the cache. |
| - (void)removeAllObjects; |
| |
| // Returns the amount of items that the cache currently hold. |
| - (NSUInteger)count; |
| |
| // Returns true if the cache is empty. |
| - (BOOL)isEmpty; |
| |
| @end |
| |
| #endif // IOS_CHROME_BROWSER_SNAPSHOTS_LRU_CACHE_H_ |