as the attribute name as the key and the value of the
 * attribute as the value in the key/value pair. This allows for easier
 * retrieval of the attributes, since all attributes have to be known.
 *
 * @since 2.5.0
 *
 * @param string $text
 * @return array|string List of attribute values.
 *                      Returns empty array if trim( $text ) == '""'.
 *                      Returns empty string if trim( $text ) == ''.
 *                      All other matches are checked for not empty().
 */
function shortcode_parse_atts($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;
}

/**
 * Combine user attributes with known attributes and fill in defaults when needed.
 *
 * The pairs should be considered to be all of the attributes which are
 * supported by the caller and given as a list. The returned attributes will
 * only contain the attributes in the $pairs list.
 *
 * If the $atts list has unsupported attributes, then they will be ignored and
 * removed from the final returned list.
 *
 * @since 2.5.0
 *
 * @param array  $pairs     Entire list of supported attributes and their defaults.
 * @param array  $atts      User defined attributes in shortcode tag.
 * @param string $shortcode Optional. The name of the shortcode, provided for context to enable filtering
 * @return array Combined and filtered attribute list.
 */
function shortcode_atts( $pairs, $atts, $shortcode = '' ) {
	$atts = (array)$atts;
	$out = array();
	foreach ($pairs as $name => $default) {
		if ( array_key_exists($name, $atts) )
			$out[$name] = $atts[$name];
		else
			$out[$name] = $default;
	}
	/**
	 * Filters a shortcode's default attributes.
	 *
	 * If the third parameter of the shortcode_atts() function is present then this filter is available.
	 * The third parameter, $shortcode, is the name of the shortcode.
	 *
	 * @since 3.6.0
	 * @since 4.4.0 Added the `$shortcode` parameter.
	 *
	 * @param array  $out       The output array of shortcode attributes.
	 * @param array  $pairs     The supported attributes and their defaults.
	 * @param array  $atts      The user defined shortcode attributes.
	 * @param string $shortcode The shortcode name.
	 */
	if ( $shortcode ) {
		$out = apply_filters( "shortcode_atts_{$shortcode}", $out, $pairs, $atts, $shortcode );
	}

	return $out;
}

/**
 * Remove all shortcode tags from the given content.
 *
 * @since 2.5.0
 *
 * @global array $shortcode_tags
 *
 * @param string $content Content to remove shortcode tags.
 * @return string Content without shortcode tags.
 */
function strip_shortcodes( $content ) {
	global $shortcode_tags;

	if ( false === strpos( $content, '[' ) ) {
		return $content;
	}

	if (empty($shortcode_tags) || !is_array($shortcode_tags))
		return $content;

	// Find all registered tag names in $content.
	preg_match_all( '@\[([^<>&/\[\]\x00-\x20=]++)@', $content, $matches );

	$tags_to_remove = array_keys( $shortcode_tags );

	/**
	 * Filters the list of shortcode tags to remove from the content.
	 *
	 * @since 4.7.0
	 *
	 * @param array  $tag_array Array of shortcode tags to remove.
	 * @param string $content   Content shortcodes are being removed from.
	 */
	$tags_to_remove = apply_filters( 'strip_shortcodes_tagnames', $tags_to_remove, $content );

	$tagnames = array_intersect( $tags_to_remove, $matches[1] );

	if ( empty( $tagnames ) ) {
		return $content;
	}

	$content = do_shortcodes_in_html_tags( $content, true, $tagnames );

	$pattern = get_shortcode_regex( $tagnames );
	$content = preg_replace_callback( "/$pattern/", 'strip_shortcode_tag', $content );

	// Always restore square braces so we don't break things like <!--[if IE ]>
	$content = unescape_invalid_shortcodes( $content );

	return $content;
}

/**
 * Strips a shortcode tag based on RegEx matches against post content.
 *
 * @since 3.3.0
 *
 * @param array $m RegEx matches against post content.
 * @return string|false The content stripped of the tag, otherwise false.
 */
function strip_shortcode_tag( $m ) {
	// allow [[foo]] syntax for escaping a tag
	if ( $m[1] == '[' && $m[6] == ']' ) {
		return substr($m[0], 1, -1);
	}

	return $m[1] . $m[6];
}