Source

File: wp-includes/kses.php

function wp_kses_attr_parse( $element ) {
	$valid = preg_match( '%^(<\s*)(/\s*)?([a-zA-Z0-9]+\s*)([^>]*)(>?)$%', $element, $matches );
	if ( 1 !== $valid ) {
		return false;
	}

	$begin  = $matches[1];
	$slash  = $matches[2];
	$elname = $matches[3];
	$attr   = $matches[4];
	$end    = $matches[5];

	if ( '' !== $slash ) {
		// Closing elements do not get parsed.
		return false;
	}

	// Is there a closing XHTML slash at the end of the attributes?
	if ( 1 === preg_match( '%\s*/\s*$%', $attr, $matches ) ) {
		$xhtml_slash = $matches[0];
		$attr        = substr( $attr, 0, -strlen( $xhtml_slash ) );
	} else {
		$xhtml_slash = '';
	}

	// Split it.
	$attrarr = wp_kses_hair_parse( $attr );
	if ( false === $attrarr ) {
		return false;
	}

	// Make sure all input is returned by adding front and back matter.
	array_unshift( $attrarr, $begin . $slash . $elname );
	array_push( $attrarr, $xhtml_slash . $end );

	return $attrarr;
}