Zekfad/lru_cache

LRU (Least recently used) cache with additional weak map layer.

LRU Cache

Cache based on Least Recently Used evict strategy.

Supports caching more than capacity via Week references (such values are cached until they garbage collected).

Features

• Supports full Map interface.
• Expando compatible objects can be optionally cached via LruWeakCache.

Usage

Create cache, add values, when space is exhausted;

// no weak cache, because String is not supported by Expando
final cache = new Cache<int, String>(2);

cache[0] = '0';
cache[1] = '1';
cache[2] = '2'; // key 0 is evicted here

cache[0]; // try to touch

print(cache[0]); // null
print(cache[1]); // 1
print(cache[2]); // 2

Example with Weak Cache support:

class Key {
  const Key(this.key);
  final String key;
  @override
  String toString() => key;
}

void main() {
  final cache = LruWeakCache<int, Key>(2);

  cache[0] = Key('0');
  cache[1] = Key('1');
  cache[2] = Key('2'); // key 0 is moved to weak cache here

  // try to touch, if key 0 is not garbage collected yet
  // key 1 is moved to weak cache, and key 0 is restored
  cache[0];

  print(cache[0]); // likely 0
  print(cache[1]); // 1
  print(cache[2]); // 2
}