wp_kses_hair_parse

	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;
}

/**
 * Builds an attribute list from string containing attributes.
 *
 * Does not modify input.  May return "evil" output.
 * In case of unexpected input, returns false instead of stripping things.
 *
 * Based on `wp_kses_hair()` but does not return a multi-dimensional array.
 *
 * @since 4.2.3
 *
 * @param string $attr Attribute list from HTML element to closing HTML element tag.
 * @return array|bool List of attributes found in $attr. Returns false on failure.
 */
function wp_kses_hair_parse( $attr ) {
	if ( '' === $attr ) {
		return array();
	}

	// phpcs:disable Squiz.Strings.ConcatenationSpacing.PaddingFound -- don't remove regex indentation
	$regex =
		'(?:'