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<?php declare(strict_types=1); |
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namespace Twistor; |
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use InvalidArgumentException; |
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use function array_key_exists; |
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use function key; |
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/** |
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* @template TKey as array-key |
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* @template TValue |
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*/ |
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final class LruCache |
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{ |
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/** |
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* @var array |
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* |
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* @psalm-var array<TKey, TValue> |
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*/ |
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private $cache = []; |
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/** |
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* @var int |
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*/ |
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private $capacity; |
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/** |
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* @var int |
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*/ |
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private $size = 0; |
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public function __construct(int $capacity) |
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{ |
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if ($capacity < 1) { |
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throw new InvalidArgumentException('Capacity must be greater than 0.'); |
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} |
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$this->capacity = $capacity; |
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} |
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/** |
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* Checks if a key exists in the cache. |
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* |
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* @param string|int $key |
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* @return bool |
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* |
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* @psalm-param TKey $key |
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* @psalm-return bool |
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*/ |
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public function has($key): bool |
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{ |
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return array_key_exists($key, $this->cache); |
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} |
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/** |
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* Returns a cache entry if it exists. |
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* |
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* @param string|int $key |
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* @return mixed|null |
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* |
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* @psalm-param TKey $key |
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* @psalm-return TValue|null |
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*/ |
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public function get($key) |
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{ |
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if ($this->has($key)) { |
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return $this->putExisting($key, $this->cache[$key]); |
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} |
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return null; |
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} |
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/** |
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* Returns an existing cache entry or calls the callback to retrieve it. |
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* |
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* @param string|int $key |
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* @param callable $callback |
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* @return mixed |
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* |
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* @psalm-param TKey $key |
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* @psalm-param callable(TKey): TValue $callback |
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* @psalm-return TValue |
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*/ |
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public function getWith($key, callable $callback) |
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{ |
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if ($this->has($key)) { |
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return $this->putExisting($key, $this->cache[$key]); |
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} |
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return $this->putNew($key, $callback($key)); |
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} |
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/** |
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* Sets a cache entry. |
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* |
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* @param string|int $key |
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* @param mixed $value |
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* |
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* @psalm-param TKey $key |
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* @psalm-param TValue $value |
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*/ |
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public function put($key, $value): void |
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{ |
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if ($this->has($key)) { |
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$this->putExisting($key, $value); |
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} else { |
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$this->putNew($key, $value); |
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} |
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} |
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/** |
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* @param string|int $key |
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* @param mixed $value |
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* @return mixed |
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* |
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* @psalm-param TKey $key |
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* @psalm-param TValue $value |
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* @psalm-return TValue |
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*/ |
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private function putExisting($key, $value) |
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{ |
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unset($this->cache[$key]); |
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return $this->cache[$key] = $value; |
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} |
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/** |
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* @param string|int $key |
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* @param mixed $value |
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* @return mixed |
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* |
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* @psalm-param TKey $key |
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* @psalm-param TValue $value |
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* @psalm-return TValue |
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*/ |
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private function putNew($key, $value) |
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{ |
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// We're at capacity; delete the least recently used cache entry. |
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if ($this->size === $this->capacity) { |
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unset($this->cache[key($this->cache)]); |
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} else { |
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++$this->size; |
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} |
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return $this->cache[$key] = $value; |
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} |
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} |
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twistor /
lru-cache
