StudipCachedArray.php

<?php
/**
 * This class represents an array in cache and removes the neccessity to
 * encode/decode and store the data after every change.
 *
 * @author  Jan-Hendrik Willms <tleilax+studip@gmail.com>
 * @license GPL2 or any later version
 * @since   Stud.IP 5.0
 */
class StudipCachedArray implements ArrayAccess
{
    protected $key;
    protected $cache;
    protected $duration;

    protected $data = [];

    protected $hash;

    /**
     * Constructs the cached array
     *
     * @param string $key      Cache key where the array is/should be stored
     *                         an int which will be length of the substring
     *                         of the given chache offset or a callable which
     *                         will return the partition key.
     * @param int    $duration Duration in seconds for which the item shall be
     *                         stored
     */
    public function __construct(string $key, int $duration = \Studip\Cache\Cache::DEFAULT_EXPIRATION)
    {
        $this->key = self::class . "/{$key}";
        $this->cache = \Studip\Cache\Factory::getCache();
        $this->duration = $duration;
        $this->hash = $this->getHash();

        $this->reset();
    }

    /**
     * Clears cached values from memory, but does not remove them from the cache.
     */
    public function reset(): void
    {
        $this->data = [];
    }

    /**
     * Removes all values from the cache.
     */
    public function expire(): void
    {
        $this->hash = $this->getHash(true);
        $this->reset();
    }

    /**
     * Determines whether an offset exists in the array.
     *
     * @param string $offset Offset
     *
     * @return bool
     */
    public function offsetExists($offset): bool
    {
        $this->loadData($offset);
        return isset($this->data[$offset]);
    }

    /**