An extremely simple key/value file cache for PHP

Cache.php

class Cache {

	/**
	 * The name of the cache file
	 * @var string
	 */
	protected $cacheFile;

	/**
	 * The cache data
	 * @var array
	 */
	protected $data = [];

	/**
	 * Construct or retrieve a cache of data from the given file
	 * @param string $file
	 */
	public function __construct($file) {
		$this->cacheFile = $file;
		if(!is_file($file)) {
			$this->saveCache();
		}
		$this->data = json_decode(file_get_contents($file), true);
	}

	/**
	 * Saves the cache when the object is destroyed
	 */
	public function __destruct() {
		$this->saveCache();
	}

	/**
	 * Save data to the cache, if there is any data to save it will delete the file to clean up
	 */
	public function saveCache() {
		if(!$this->data) {
			return $this->deleteCache();
		}
		file_put_contents($this->cacheFile, json_encode($this->data));
		return $this;
	}

	/**
	 * Deletes all of the data and the cache file
	 * @return $this
	 */
	public function deleteCache() {
		$this->data = [];
		if(is_file($this->cacheFile)) {
			unlink($this->cacheFile);
		}
		return $this;
	}

	/**
	 * Gets all of the data
	 * @return array
	 */
	public function getData() {
		return $this->data;
	}

	/**
	 * Get the value for a given key
	 * @param $key
	 * @return mixed|null
	 */
	public function getValueForKey($key) {
		if(array_key_exists($key, $this->data)) {
			return $this->data[$key];
		}
		return null;
	}

	/**
	 * Set the value for a given key
	 * @param $key
	 * @param $value
	 * @return $this
	 */
	public function setValueForKey($key, $value) {
		$this->data[$key] = $value;
		return $this;
	}

}