S2OJ/web/app/vendor/ezyang/htmlpurifier/library/HTMLPurifier/StringHash.php

<?php

/**
 * This is in almost every respect equivalent to an array except
 * that it keeps track of which keys were accessed.
 *
 * @warning For the sake of backwards compatibility with early versions
 *     of PHP 5, you must not use the $hash[$key] syntax; if you do
 *     our version of offsetGet is never called.
 */
class HTMLPurifier_StringHash extends ArrayObject
{
    /**
     * @type array
     */
    protected $accessed = array();

    /**
     * Retrieves a value, and logs the access.
     * @param mixed $index
     * @return mixed
     */
    #[\ReturnTypeWillChange]
    public function offsetGet($index)
    {
        $this->accessed[$index] = true;
        return parent::offsetGet($index);
    }

    /**
     * Returns a lookup array of all array indexes that have been accessed.
     * @return array in form array($index => true).
     */
    public function getAccessed()
    {
        return $this->accessed;
    }

    /**
     * Resets the access array.
     */
    public function resetAccessed()
    {
        $this->accessed = array();
    }
}

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