Source

File: wp-includes/shortcodes.php

function shortcode_parse_atts( $text ) {
	$atts    = array();
	$pattern = get_shortcode_atts_regex();
	$text    = preg_replace( "/[\x{00a0}\x{200b}]+/u", ' ', $text );
	if ( preg_match_all( $pattern, $text, $match, PREG_SET_ORDER ) ) {
		foreach ( $match as $m ) {
			if ( ! empty( $m[1] ) ) {
				$atts[ strtolower( $m[1] ) ] = stripcslashes( $m[2] );
			} elseif ( ! empty( $m[3] ) ) {
				$atts[ strtolower( $m[3] ) ] = stripcslashes( $m[4] );
			} elseif ( ! empty( $m[5] ) ) {
				$atts[ strtolower( $m[5] ) ] = stripcslashes( $m[6] );
			} elseif ( isset( $m[7] ) && strlen( $m[7] ) ) {
				$atts[] = stripcslashes( $m[7] );
			} elseif ( isset( $m[8] ) && strlen( $m[8] ) ) {
				$atts[] = stripcslashes( $m[8] );
			} elseif ( isset( $m[9] ) ) {
				$atts[] = stripcslashes( $m[9] );
			}
		}

		// Reject any unclosed HTML elements.
		foreach ( $atts as &$value ) {
			if ( false !== strpos( $value, '<' ) ) {
				if ( 1 !== preg_match( '/^[^<]*+(?:<[^>]*+>[^<]*+)*+$/', $value ) ) {
					$value = '';
				}
			}
		}
	} else {
		$atts = ltrim( $text );
	}

	return $atts;
}