* Adds a rewrite rule that transforms a URL structure to a set of query vars.

 *

 * Any value in the $after parameter that isn't 'bottom' will result in the rule

 * being placed at the top of the rewrite rules.

 *

 * @since 2.1.0

 * @since 4.4.0 Array support was added to the `$query` parameter.

 *

 * @global WP_Rewrite $wp_rewrite WordPress Rewrite Component.

 *

 * @param string       $regex Regular expression to match request against.

 * @param string|array $query The corresponding query vars for this rewrite rule.

 * @param string       $after Optional. Priority of the new rule. Accepts 'top'

 *                            or 'bottom'. Default 'bottom'.

 */

function add_rewrite_rule( $regex, $query, $after = 'bottom' ) {

	global $wp_rewrite;

	$wp_rewrite->add_rule( $regex, $query, $after );

}

/**

 * Add a new rewrite tag (like %postname%).

 *

 * The $query parameter is optional. If it is omitted you must ensure that

 * you call this on, or before, the {@see 'init'} hook. This is because $query defaults

 * to "$tag=", and for this to work a new query var has to be added.

 *

 * @since 2.1.0

 *

 * @global WP_Rewrite $wp_rewrite

 * @global WP         $wp

 *

 * @param string $tag   Name of the new rewrite tag.

 * @param string $regex Regular expression to substitute the tag for in rewrite rules.

 * @param string $query Optional. String to append to the rewritten query. Must end in '='. Default empty.

 */

function add_rewrite_tag( $tag, $regex, $query = '' ) {

	// validate the tag's name

	if ( strlen( $tag ) < 3 || $tag[0] != '%' || $tag[ strlen($tag) - 1 ] != '%' )

		return;

	global $wp_rewrite, $wp;

	if ( empty( $query ) ) {

		$qv = trim( $tag, '%' );

		$wp->add_query_var( $qv );

		$query = $qv . '=';

	}

	$wp_rewrite->add_rewrite_tag( $tag, $regex, $query );

}

/**

 * Removes an existing rewrite tag (like %postname%).

 *

 * @since 4.5.0

 *

 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.

 *

 * @param string $tag Name of the rewrite tag.

 */

function remove_rewrite_tag( $tag ) {

	global $wp_rewrite;

	$wp_rewrite->remove_rewrite_tag( $tag );

}

/**

 * Add permalink structure.

 *

 * @since 3.0.0

 *

 * @see WP_Rewrite::add_permastruct()

 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.

 *

 * @param string $name   Name for permalink structure.

 * @param string $struct Permalink structure.

 * @param array  $args   Optional. Arguments for building the rules from the permalink structure,

 *                       see WP_Rewrite::add_permastruct() for full details. Default empty array.

 */

function add_permastruct( $name, $struct, $args = array() ) {

	global $wp_rewrite;

	// Back-compat for the old parameters: $with_front and $ep_mask.

	if ( ! is_array( $args ) )

		$args = array( 'with_front' => $args );

	if ( func_num_args() == 4 )

		$args['ep_mask'] = func_get_arg( 3 );

	$wp_rewrite->add_permastruct( $name, $struct, $args );

}

/**

 * Removes a permalink structure.

 *

 * Can only be used to remove permastructs that were added using add_permastruct().

 * Built-in permastructs cannot be removed.

 *

 * @since 4.5.0

 *

 * @see WP_Rewrite::remove_permastruct()

 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.

 *

 * @param string $name Name for permalink structure.

 */

function remove_permastruct( $name ) {

	global $wp_rewrite;

	$wp_rewrite->remove_permastruct( $name );

}

/**

 * Add a new feed type like /atom1/.

 *

 * @since 2.1.0

 *

 * @global WP_Rewrite $wp_rewrite

 *

 * @param string   $feedname Feed name.

 * @param callable $function Callback to run on feed display.

 * @return string Feed action name.

 */

function add_feed( $feedname, $function ) {

	global $wp_rewrite;

	if ( ! in_array( $feedname, $wp_rewrite->feeds ) ) {

		$wp_rewrite->feeds[] = $feedname;

	}

	$hook = 'do_feed_' . $feedname;

	// Remove default function hook

	remove_action( $hook, $hook );

	add_action( $hook, $function, 10, 2 );

	return $hook;

}

/**

 * Remove rewrite rules and then recreate rewrite rules.

 *

 * @since 3.0.0

 *

 * @global WP_Rewrite $wp_rewrite

 *

 * @param bool $hard Whether to update .htaccess (hard flush) or just update

 * 	                 rewrite_rules transient (soft flush). Default is true (hard).

 */

function flush_rewrite_rules( $hard = true ) {

	global $wp_rewrite;

	$wp_rewrite->flush_rules( $hard );

}

/**

 * Be sure to flush the rewrite rules - see flush_rewrite_rules() - when your plugin gets

 * @since 4.3.0 Added support for skipping query var registration by passing `false` to `$query_var`.

 *

 * @global WP_Rewrite $wp_rewrite

 * @param string      $name      Name of the endpoint.

 * @param int         $places    Endpoint mask describing the places the endpoint should be added.

 * @param string|bool $query_var Name of the corresponding query variable. Pass `false` to skip registering a query_var

 *                               for this endpoint. Defaults to the value of `$name`.

function add_rewrite_endpoint( $name, $places, $query_var = true ) {

 * Filters the URL base for taxonomies.

 * Resolve numeric slugs that collide with date permalinks.

 *

 * Permalinks of posts with numeric slugs can sometimes look to WP_Query::parse_query()

 * like a date archive, as when your permalink structure is `/%year%/%postname%/` and

 * a post with post_name '05' has the URL `/2015/05/`.

 *

 * This function detects conflicts of this type and resolves them in favor of the

 * post permalink.

 *

 * Note that, since 4.3.0, wp_unique_post_slug() prevents the creation of post slugs

 * that would result in a date archive conflict. The resolution performed in this

 * function is primarily for legacy content, as well as cases when the admin has changed

 * the site's permalink structure in a way that introduces URL conflicts.

 *

 * @since 4.3.0

 *

 * @param array $query_vars Optional. Query variables for setting up the loop, as determined in

 *                          WP::parse_request(). Default empty array.

 * @return array Returns the original array of query vars, with date/post conflicts resolved.

 */

function wp_resolve_numeric_slug_conflicts( $query_vars = array() ) {

	if ( ! isset( $query_vars['year'] ) && ! isset( $query_vars['monthnum'] ) && ! isset( $query_vars['day'] ) ) {

		return $query_vars;

	}

	// Identify the 'postname' position in the permastruct array.

	$permastructs   = array_values( array_filter( explode( '/', get_option( 'permalink_structure' ) ) ) );

	$postname_index = array_search( '%postname%', $permastructs );

	if ( false === $postname_index ) {

		return $query_vars;

	}

	/*

	 * A numeric slug could be confused with a year, month, or day, depending on position. To account for

	 * the possibility of post pagination (eg 2015/2 for the second page of a post called '2015'), our

	 * `is_*` checks are generous: check for year-slug clashes when `is_year` *or* `is_month`, and check

	 * for month-slug clashes when `is_month` *or* `is_day`.

	 */

	$compare = '';

	if ( 0 === $postname_index && ( isset( $query_vars['year'] ) || isset( $query_vars['monthnum'] ) ) ) {

		$compare = 'year';

	} elseif ( '%year%' === $permastructs[ $postname_index - 1 ] && ( isset( $query_vars['monthnum'] ) || isset( $query_vars['day'] ) ) ) {

		$compare = 'monthnum';

	} elseif ( '%monthnum%' === $permastructs[ $postname_index - 1 ] && isset( $query_vars['day'] ) ) {

		$compare = 'day';

	}

	if ( ! $compare ) {

		return $query_vars;

	}

	// This is the potentially clashing slug.

	$value = $query_vars[ $compare ];

	$post = get_page_by_path( $value, OBJECT, 'post' );

	if ( ! ( $post instanceof WP_Post ) ) {

		return $query_vars;

	}

	// If the date of the post doesn't match the date specified in the URL, resolve to the date archive.

	if ( preg_match( '/^([0-9]{4})\-([0-9]{2})/', $post->post_date, $matches ) && isset( $query_vars['year'] ) && ( 'monthnum' === $compare || 'day' === $compare ) ) {

		// $matches[1] is the year the post was published.

		if ( intval( $query_vars['year'] ) !== intval( $matches[1] ) ) {

			return $query_vars;

		}

		// $matches[2] is the month the post was published.

		if ( 'day' === $compare && isset( $query_vars['monthnum'] ) && intval( $query_vars['monthnum'] ) !== intval( $matches[2] ) ) {

			return $query_vars;

		}

	}

	/*

	 * If the located post contains nextpage pagination, then the URL chunk following postname may be

	 * intended as the page number. Verify that it's a valid page before resolving to it.

	 */

	$maybe_page = '';

	if ( 'year' === $compare && isset( $query_vars['monthnum'] ) ) {

		$maybe_page = $query_vars['monthnum'];

	} elseif ( 'monthnum' === $compare && isset( $query_vars['day'] ) ) {

		$maybe_page = $query_vars['day'];

	}

	// Bug found in #11694 - 'page' was returning '/4'

	$maybe_page = (int) trim( $maybe_page, '/' );

	$post_page_count = substr_count( $post->post_content, '<!--nextpage-->' ) + 1;

	// If the post doesn't have multiple pages, but a 'page' candidate is found, resolve to the date archive.

	if ( 1 === $post_page_count && $maybe_page ) {

		return $query_vars;

	}

	// If the post has multiple pages and the 'page' number isn't valid, resolve to the date archive.

	if ( $post_page_count > 1 && $maybe_page > $post_page_count ) {

		return $query_vars;

	}

	// If we've gotten to this point, we have a slug/date clash. First, adjust for nextpage.

	if ( '' !== $maybe_page ) {