<?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 $index        	
	 * @return mixed
	 */
	public function offsetGet($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 ();
	}
}

// vim: et sw=4 sts=4