38 lines
769 B
Dart
38 lines
769 B
Dart
// @dart=2.9
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import 'dart:collection';
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typedef EvictionHandler<K, V> = Function(K key, V value);
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class LRUMap<K, V> {
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final LinkedHashMap<K, V> _map = LinkedHashMap<K, V>();
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final int _maxSize;
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final EvictionHandler<K, V> _handler;
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LRUMap(this._maxSize, [this._handler]);
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V get(K key) {
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final V value = _map.remove(key);
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if (value != null) {
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_map[key] = value;
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}
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return value;
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}
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void put(K key, V value) {
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_map.remove(key);
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_map[key] = value;
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if (_map.length > _maxSize) {
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final K evictedKey = _map.keys.first;
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final V evictedValue = _map.remove(evictedKey);
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if (_handler != null) {
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_handler(evictedKey, evictedValue);
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}
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}
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}
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void remove(K key) {
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_map.remove(key);
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}
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}
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