* WordPress API for creating bbcode-like tags or what WordPress calls
* "shortcodes". The tag and attribute parsing or regular expression code is
* based on the Textpattern tag parser.
* A few examples are below:
* [shortcode foo="bar" baz="bing" /]
* [shortcode foo="bar"]content[/shortcode]
* Shortcode tags support attributes and enclosed content, but does not entirely
* support inline shortcodes in other shortcodes. You will have to call the
* shortcode parser in your function to account for that.
* Please be aware that the above note was made during the beta of WordPress 2.6
* and in the future may not be accurate. Please update the note when it is no
* To apply shortcode tags to content:
* $out = do_shortcode( $content );
* @link https://developer.wordpress.org/plugins/shortcodes/
* Container for storing shortcode tags and their hook to call for the shortcode
* @global array $shortcode_tags
$shortcode_tags = array();
* Care should be taken through prefixing or other means to ensure that the
* shortcode tag being added is unique and will not conflict with other,
* already-added shortcode tags. In the event of a duplicated tag, the tag
* loaded last will take precedence.
* @global array $shortcode_tags
* @param string $tag Shortcode tag to be searched in post content.
* @param callable $callback The callback function to run when the shortcode is found.
* Every shortcode callback is passed three parameters by default,
* including an array of attributes (`$atts`), the shortcode content
* or null if not set (`$content`), and finally the shortcode tag
* itself (`$shortcode_tag`), in that order.
function add_shortcode( $tag, $callback ) {
if ( '' === trim( $tag ) ) {
$message = __( 'Invalid shortcode name: Empty name given.' );
_doing_it_wrong( __FUNCTION__, $message, '4.4.0' );
if ( 0 !== preg_match( '@[<>&/\[\]\x00-\x20=]@', $tag ) ) {
/* translators: 1: Shortcode name, 2: Space-separated list of reserved characters. */
$message = sprintf( __( 'Invalid shortcode name: %1$s. Do not use spaces or reserved characters: %2$s' ), $tag, '& / < > [ ] =' );
_doing_it_wrong( __FUNCTION__, $message, '4.4.0' );
$shortcode_tags[ $tag ] = $callback;
* Removes hook for shortcode.
* @global array $shortcode_tags
* @param string $tag Shortcode tag to remove hook for.
function remove_shortcode( $tag ) {
unset( $shortcode_tags[ $tag ] );
* This function is simple, it clears all of the shortcode tags by replacing the
* shortcodes global by a empty array. This is actually a very efficient method
* for removing all shortcodes.
* @global array $shortcode_tags
function remove_all_shortcodes() {
$shortcode_tags = array();
* Whether a registered shortcode exists named $tag
* @global array $shortcode_tags List of shortcode tags and their callback hooks.
* @param string $tag Shortcode tag to check.
* @return bool Whether the given shortcode exists.
function shortcode_exists( $tag ) {
return array_key_exists( $tag, $shortcode_tags );
* Whether the passed content contains the specified shortcode
* @global array $shortcode_tags
* @param string $content Content to search for shortcodes.
* @param string $tag Shortcode tag to check.
* @return bool Whether the passed content contains the given shortcode.
function has_shortcode( $content, $tag ) {
if ( false === strpos( $content, '[' ) ) {
if ( shortcode_exists( $tag ) ) {
preg_match_all( '/' . get_shortcode_regex() . '/', $content, $matches, PREG_SET_ORDER );
if ( empty( $matches ) ) {
foreach ( $matches as $shortcode ) {
if ( $tag === $shortcode[2] ) {
} elseif ( ! empty( $shortcode[5] ) && has_shortcode( $shortcode[5], $tag ) ) {
* Returns a list of registered shortcode names found in the given content.
* get_shortcode_tags_in_content( '[audio src="file.mp3"][/audio] [foo] [gallery ids="1,2,3"]' );
* // array( 'audio', 'gallery' )
* @param string $content The content to check.
* @return string[] An array of registered shortcode names found in the content.
function get_shortcode_tags_in_content( $content ) {
if ( false === strpos( $content, '[' ) ) {
preg_match_all( '/' . get_shortcode_regex() . '/', $content, $matches, PREG_SET_ORDER );
if ( empty( $matches ) ) {
foreach ( $matches as $shortcode ) {
if ( ! empty( $shortcode[5] ) ) {
$deep_tags = get_shortcode_tags_in_content( $shortcode[5] );
if ( ! empty( $deep_tags ) ) {
$tags = array_merge( $tags, $deep_tags );
* Searches content for shortcodes and filter shortcodes through their hooks.
* This function is an alias for do_shortcode().
* @param string $content Content to search for shortcodes.
* @param bool $ignore_html When true, shortcodes inside HTML elements will be skipped.
* @return string Content with shortcodes filtered out.
function apply_shortcodes( $content, $ignore_html = false ) {
return do_shortcode( $content, $ignore_html );
* Search content for shortcodes and filter shortcodes through their hooks.
* If there are no shortcode tags defined, then the content will be returned
* without any filtering. This might cause issues when plugins are disabled but
* the shortcode will still show up in the post or content.
* @global array $shortcode_tags List of shortcode tags and their callback hooks.
* @param string $content Content to search for shortcodes.
* @param bool $ignore_html When true, shortcodes inside HTML elements will be skipped.
* @return string Content with shortcodes filtered out.
function do_shortcode( $content, $ignore_html = false ) {
if ( false === strpos( $content, '[' ) ) {
if ( empty( $shortcode_tags ) || ! is_array( $shortcode_tags ) ) {
// Find all registered tag names in $content.
preg_match_all( '@\[([^<>&/\[\]\x00-\x20=]++)@', $content, $matches );
$tagnames = array_intersect( array_keys( $shortcode_tags ), $matches[1] );
if ( empty( $tagnames ) ) {
$content = do_shortcodes_in_html_tags( $content, $ignore_html, $tagnames );
$pattern = get_shortcode_regex( $tagnames );
$content = preg_replace_callback( "/$pattern/", 'do_shortcode_tag', $content );
// Always restore square braces so we don't break things like <!--[if IE ]>.
$content = unescape_invalid_shortcodes( $content );
* Retrieve the shortcode regular expression for searching.
* The regular expression combines the shortcode tags in the regular expression
* The regular expression contains 6 different sub matches to help with parsing.
* 1 - An extra [ to allow for escaping shortcodes with double [[]]
* 3 - The shortcode argument list
* 5 - The content of a shortcode when it wraps some content.
* 6 - An extra ] to allow for escaping shortcodes with double [[]]
* @since 4.4.0 Added the `$tagnames` parameter.
* @global array $shortcode_tags
* @param array $tagnames Optional. List of shortcodes to find. Defaults to all registered shortcodes.
* @return string The shortcode search regular expression
function get_shortcode_regex( $tagnames = null ) {
if ( empty( $tagnames ) ) {
$tagnames = array_keys( $shortcode_tags );
$tagregexp = implode( '|', array_map( 'preg_quote', $tagnames ) );
// WARNING! Do not change this regex without changing do_shortcode_tag() and strip_shortcode_tag().
// Also, see shortcode_unautop() and shortcode.js.
// phpcs:disable Squiz.Strings.ConcatenationSpacing.PaddingFound -- don't remove regex indentation
return '\\[' // Opening bracket.
. '(\\[?)' // 1: Optional second opening bracket for escaping shortcodes: [[tag]].
. "($tagregexp)" // 2: Shortcode name.
. '(?![\\w-])' // Not followed by word character or hyphen.
. '(' // 3: Unroll the loop: Inside the opening shortcode tag.
. '[^\\]\\/]*' // Not a closing bracket or forward slash.
. '\\/(?!\\])' // A forward slash not followed by a closing bracket.
. '[^\\]\\/]*' // Not a closing bracket or forward slash.
. '(\\/)' // 4: Self closing tag...
. '\\]' // ...and closing bracket.
. '\\]' // Closing bracket.
. '(' // 5: Unroll the loop: Optionally, anything between the opening and closing shortcode tags.
. '[^\\[]*+' // Not an opening bracket.
. '\\[(?!\\/\\2\\])' // An opening bracket not followed by the closing shortcode tag.
. '[^\\[]*+' // Not an opening bracket.
. '\\[\\/\\2\\]' // Closing shortcode tag.
. '(\\]?)'; // 6: Optional second closing brocket for escaping shortcodes: [[tag]].
* Regular Expression callable for do_shortcode() for calling shortcode hook.
* @see get_shortcode_regex() for details of the match array contents.
* @global array $shortcode_tags
* @param array $m Regular expression match array.
* @return string|false Shortcode output on success, false on failure.
function do_shortcode_tag( $m ) {
// Allow [[foo]] syntax for escaping a tag.
if ( '[' === $m[1] && ']' === $m[6] ) {
return substr( $m[0], 1, -1 );
$attr = shortcode_parse_atts( $m[3] );
if ( ! is_callable( $shortcode_tags[ $tag ] ) ) {
/* translators: %s: Shortcode tag. */
$message = sprintf( __( 'Attempting to parse a shortcode without a valid callback: %s' ), $tag );
_doing_it_wrong( __FUNCTION__, $message, '4.3.0' );
* Filters whether to call a shortcode callback.
* Returning a non-false value from filter will short-circuit the
* shortcode generation process, returning that value instead.
* @param false|string $return Short-circuit return value. Either false or the value to replace the shortcode with.
* @param string $tag Shortcode name.
* @param array|string $attr Shortcode attributes array or empty string.
* @param array $m Regular expression match array.
$return = apply_filters( 'pre_do_shortcode_tag', false, $tag, $attr, $m );
if ( false !== $return ) {
$content = isset( $m[5] ) ? $m[5] : null;
$output = $m[1] . call_user_func( $shortcode_tags[ $tag ], $attr, $content, $tag ) . $m[6];
* Filters the output created by a shortcode callback.
* @param string $output Shortcode output.
* @param string $tag Shortcode name.
* @param array|string $attr Shortcode attributes array or empty string.
* @param array $m Regular expression match array.
return apply_filters( 'do_shortcode_tag', $output, $tag, $attr, $m );
* Search only inside HTML elements for shortcodes and process them.
* Any [ or ] characters remaining inside elements will be HTML encoded
* to prevent interference with shortcodes that are outside the elements.
* Assumes $content processed by KSES already. Users with unfiltered_html
* capability may get unexpected output if angle braces are nested in tags.
* @param string $content Content to search for shortcodes.
* @param bool $ignore_html When true, all square braces inside elements will be encoded.
* @param array $tagnames List of shortcodes to find.
* @return string Content with shortcodes filtered out.
function do_shortcodes_in_html_tags( $content, $ignore_html, $tagnames ) {
// Normalize entities in unfiltered HTML before adding placeholders.
$content = strtr( $content, $trans );
$pattern = get_shortcode_regex( $tagnames );
$textarr = wp_html_split( $content );
foreach ( $textarr as &$element ) {
if ( '' === $element || '<' !== $element[0] ) {
$noopen = false === strpos( $element, '[' );
$noclose = false === strpos( $element, ']' );
if ( $noopen || $noclose ) {
// This element does not contain shortcodes.
if ( $noopen xor $noclose ) {
// Need to encode stray '[' or ']' chars.
$element = strtr( $element, $trans );
if ( $ignore_html || '<!--' === substr( $element, 0, 4 ) || '<![CDATA[' === substr( $element, 0, 9 ) ) {
// Encode all '[' and ']' chars.
$element = strtr( $element, $trans );
$attributes = wp_kses_attr_parse( $element );
if ( false === $attributes ) {
// Some plugins are doing things like [name] <[email]>.
if ( 1 === preg_match( '%^<\s*\[\[?[^\[\]]+\]%', $element ) ) {
$element = preg_replace_callback( "/$pattern/", 'do_shortcode_tag', $element );
// Looks like we found some crazy unfiltered HTML. Skipping it for sanity.
$element = strtr( $element, $trans );
$front = array_shift( $attributes );
$back = array_pop( $attributes );
preg_match( '%[a-zA-Z0-9]+%', $front, $matches );
// Look for shortcodes in each attribute separately.
foreach ( $attributes as &$attr ) {
$open = strpos( $attr, '[' );
$close = strpos( $attr, ']' );
if ( false === $open || false === $close ) {
continue; // Go to next attribute. Square braces will be escaped at end of loop.
$double = strpos( $attr, '"' );
$single = strpos( $attr, "'" );
if ( ( false === $single || $open < $single ) && ( false === $double || $open < $double ) ) {
* $attr like '[shortcode]' or 'name = [shortcode]' implies unfiltered_html.
* In this specific situation we assume KSES did not run because the input
* was written by an administrator, so we should avoid changing the output
* and we do not need to run KSES here.
$attr = preg_replace_callback( "/$pattern/", 'do_shortcode_tag', $attr );
// $attr like 'name = "[shortcode]"' or "name = '[shortcode]'".
// We do not know if $content was unfiltered. Assume KSES ran before shortcodes.
$new_attr = preg_replace_callback( "/$pattern/", 'do_shortcode_tag', $attr, -1, $count );
// Sanitize the shortcode output using KSES.
$new_attr = wp_kses_one_attr( $new_attr, $elname );
if ( '' !== trim( $new_attr ) ) {
// The shortcode is safe to use now.
$element = $front . implode( '', $attributes ) . $back;
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