<?php

/**

 * WP_MatchesMapRegex helper class

 *

 * @package WordPress

 * @since 4.7.0

 */

/**

 * Helper class to remove the need to use eval to replace $matches[] in query strings.

 *

 * @since 2.9.0

 */

class WP_MatchesMapRegex {

	/**

	 * store for matches

	 *

	 * @var array

	 */

	private $_matches;

	/**

	 * store for mapping result

	 *

	 * @var string

	 */

	public $output;

	/**

	 * subject to perform mapping on (query string containing $matches[] references

	 *

	 * @var string

	 */

	private $_subject;

	/**

	 * regexp pattern to match $matches[] references

	 *

	 * @var string

	 */

	public $_pattern = '(\$matches\[[1-9]+[0-9]*\])'; // magic number

	/**

	 * constructor

	 *

	 * @param string $subject subject if regex

	 * @param array  $matches data to use in map

	 */

	public function __construct( $subject, $matches ) {

		$this->_subject = $subject;

		$this->_matches = $matches;

		$this->output   = $this->_map();

	}

	/**

	 * Substitute substring matches in subject.

	 *

	 * static helper function to ease use

	 *

	 * @param string $subject subject

	 * @param array  $matches data used for substitution

	 * @return string

	 */

	public static function apply( $subject, $matches ) {

		$oSelf = new WP_MatchesMapRegex( $subject, $matches );

		return $oSelf->output;

	}

	/**

	 * do the actual mapping

	 *

	 * @return string

	 */

	private function _map() {

		$callback = array( $this, 'callback' );

		return preg_replace_callback( $this->_pattern, $callback, $this->_subject );

	}

	/**

	 * preg_replace_callback hook

	 *

	 * @param  array $matches preg_replace regexp matches

	 * @return string

	 */

	public function callback( $matches ) {

		$index = intval( substr( $matches[0], 9, -1 ) );

		return ( isset( $this->_matches[ $index ] ) ? urlencode( $this->_matches[ $index ] ) : '' );

	}

}