* WordPress implementation for PHP functions either missing from older PHP versions or not included by default.

// If gettext isn't available

if ( !function_exists('mb_substr') ):

	function mb_substr( $str, $start, $length=null, $encoding=null ) {

		return _mb_substr($str, $start, $length, $encoding);

endif;

function _mb_substr( $str, $start, $length=null, $encoding=null ) {

	// the solution below, works only for utf-8, so in case of a different

	// charset, just use built-in substr

	$charset = get_option( 'blog_charset' );

	if ( !in_array( $charset, array('utf8', 'utf-8', 'UTF8', 'UTF-8') ) ) {

		return is_null( $length )? substr( $str, $start ) : substr( $str, $start, $length);

	}

	// use the regex unicode support to separate the UTF-8 characters into an array

	preg_match_all( '/./us', $str, $match );

	$chars = is_null( $length )? array_slice( $match[0], $start ) : array_slice( $match[0], $start, $length );

	return implode( '', $chars );

			require_once( ABSPATH . WPINC . '/class-json.php' );

	function json_decode( $string, $assoc_array = false ) {

			require_once( ABSPATH . WPINC . '/class-json.php' );

		$res = $wp_json->decode( $string );

		if ( $assoc_array )

			$res = _json_decode_object_helper( $res );

		return $res;

	}

	function _json_decode_object_helper($data) {

		if ( is_object($data) )

			$data = get_object_vars($data);

		return is_array($data) ? array_map(__FUNCTION__, $data) : $data;