bookmark field.
 *
 * Sanitizes the bookmark fields based on what the field name is. If the field
 * has a strict value set, then it will be tested for that, else a more generic
 * filtering is applied. After the more strict filter is applied, if the `$context`
 * is 'raw' then the value is immediately return.
 *
 * Hooks exist for the more generic cases. With the 'edit' context, the {@see 'edit_$field'}
 * filter will be called and passed the `$value` and `$bookmark_id` respectively.
 *
 * With the 'db' context, the {@see 'pre_$field'} filter is called and passed the value.
 * The 'display' context is the final context and has the `$field` has the filter name
 * and is passed the `$value`, `$bookmark_id`, and `$context`, respectively.
 *
 * @since 2.3.0
 *
 * @param string $field       The bookmark field.
 * @param mixed  $value       The bookmark field value.
 * @param int    $bookmark_id Bookmark ID.
 * @param string $context     How to filter the field value. Accepts 'raw', 'edit', 'db',
 *                            'display', 'attribute', or 'js'. Default 'display'.
 * @return mixed The filtered value.
 */
function sanitize_bookmark_field( $field, $value, $bookmark_id, $context ) {
	$int_fields = array( 'link_id', 'link_rating' );
	if ( in_array( $field, $int_fields, true ) ) {
		$value = (int) $value;
	}

	switch ( $field ) {
		case 'link_category': // array( ints )
			$value = array_map( 'absint', (array) $value );
			/*
			 * We return here so that the categories aren't filtered.
			 * The 'link_category' filter is for the name of a link category, not an array of a link's link categories.
			 */
			return $value;

		case 'link_visible': // bool stored as Y|N
			$value = preg_replace( '/[^YNyn]/', '', $value );
			break;
		case 'link_target': // "enum"
			$targets = array( '_top', '_blank' );
			if ( ! in_array( $value, $targets, true ) ) {
				$value = '';
			}
			break;
	}

	if ( 'raw' === $context ) {
		return $value;
	}

	if ( 'edit' === $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "edit_{$field}", $value, $bookmark_id );

		if ( 'link_notes' === $field ) {
			$value = esc_html( $value ); // textarea_escaped
		} else {
			$value = esc_attr( $value );
		}
	} elseif ( 'db' === $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "pre_{$field}", $value );
	} else {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "{$field}", $value, $bookmark_id, $context );

		if ( 'attribute' === $context ) {
			$value = esc_attr( $value );
		} elseif ( 'js' === $context ) {
			$value = esc_js( $value );
		}
	}

	// Restore the type for integer fields after esc_attr().
	if ( in_array( $field, $int_fields, true ) ) {
		$value = (int) $value;
	}

	return $value;
}

/**
 * Deletes the bookmark cache.
 *
 * @since 2.7.0
 *
 * @param int $bookmark_id Bookmark ID.
 */
function clean_bookmark_cache( $bookmark_id ) {
	wp_cache_delete( $bookmark_id, 'bookmark' );
	wp_cache_delete( 'get_bookmarks', 'bookmark' );
	clean_object_term_cache( $bookmark_id, 'link' );
}
le_li.
 *                                          Default 'linkcat'.
 *     @type string       $category_before  The HTML or text to prepend to $title_before if $categorize is true.
 *                                          String must contain '%id' and '%class' to inherit the category ID and
 *                                          the $class argument used for formatting in themes.
 *                                          Default '<li id="%id" class="%class">'.
 *     @type string       $category_after   The HTML or text to append to $title_after if $categorize is true.
 *                                          Default '</li>'.
 *     @type string       $category_orderby How to order the bookmark category based on term scheme if $categorize
 *                                          is true. Default 'name'.
 *     @type string       $category_order   Whether to order categories in ascending or descending order if
 *                                          $categorize is true. Accepts 'ASC' (ascending) or 'DESC' (descending).
 *                                          Default 'ASC'.
 * }
 * @return void|string Void if 'echo' argument is true, HTML list of bookmarks if 'echo' is false.
 */
function wp_list_bookmarks( $args = '' ) {
	$defaults = array(
		'orderby'          => 'name',
		'order'            => 'ASC',
		'limit'            => -1,
		'category'         => '',
		'exclude_category' => '',
		'category_name'    => '',
		'hide_invisible'   => 1,
		'show_updated'     => 0,
		'echo'             => 1,
		'categorize'       => 1,
		'title_li'         => __( 'Bookmarks' ),
		'title_before'     => '<h2>',
		'title_after'      => '</h2>',
		'category_orderby' => 'name',
		'category_order'   => 'ASC',
		'class'            => 'linkcat',
		'category_before'  => '<li id="%id" class="%class">',
		'category_after'   => '</li>',
	);

	$parsed_args = wp_parse_args( $args, $defaults );

	$output = '';

	if ( ! is_array( $parsed_args['class'] ) ) {
		$parsed_args['class'] = explode( ' ', $parsed_args['class'] );
	}
	$parsed_args['class'] = array_map( 'sanitize_html_class', $parsed_args['class'] );
	$parsed_args['class'] = trim( implode( ' ', $parsed_args['class'] ) );

	if ( $parsed_args['categorize'] ) {
		$cats = get_terms(
			array(
				'taxonomy'     => 'link_category',
				'name__like'   => $parsed_args['category_name'],
				'include'      => $parsed_args['category'],
				'exclude'      => $parsed_args['exclude_category'],
				'orderby'      => $parsed_args['category_orderby'],
				'order'        => $parsed_args['category_order'],
				'hierarchical' => 0,
			)
		);
		if ( empty( $cats ) ) {
			$parsed_args['categorize'] = false;
		}
	}

	if ( $parsed_args['categorize'] ) {
		// Split the bookmarks into ul's for each category.
		foreach ( (array) $cats as $cat ) {
			$params    = array_merge( $parsed_args, array( 'category' => $cat->term_id ) );
			$bookmarks = get_bookmarks( $params );
			if ( empty( $bookmarks ) ) {
				continue;
			}
			$output .= str_replace(
				array( '%id', '%class' ),
				array( "linkcat-$cat->term_id", $parsed_args['class'] ),
				$parsed_args['category_before']
			);
			/**
			 * Filters the category name.
			 *
			 * @since 2.2.0
			 *
			 * @param string $cat_name The category name.
			 */
			$catname = apply_filters( 'link_category', $cat->name );

			$output .= $parsed_args['title_before'];
			$output .= $catname;
			$output .= $parsed_args['title_after'];
			$output .= "\n\t<ul class='xoxo blogroll'>\n";
			$output .= _walk_bookmarks( $bookmarks, $parsed_args );
			$output .= "\n\t</ul>\n";
			$output .= $parsed_args['category_after'] . "\n";
		}
	} else {
		// Output one single list using title_li for the title.
		$bookmarks = get_bookmarks( $parsed_args );

		if ( ! empty( $bookmarks ) ) {
			if ( ! empty( $parsed_args['title_li'] ) ) {
				$output .= str_replace(
					array( '%id', '%class' ),
					array( 'linkcat-' . $parsed_args['category'], $parsed_args['class'] ),
					$parsed_args['category_before']
				);
				$output .= $parsed_args['title_before'];
				$output .= $parsed_args['title_li'];
				$output .= $parsed_args['title_after'];
				$output .= "\n\t<ul class='xoxo blogroll'>\n";
				$output .= _walk_bookmarks( $bookmarks, $parsed_args );
				$output .= "\n\t</ul>\n";
				$output .= $parsed_args['category_after'] . "\n";
			} else {
				$output .= _walk_bookmarks( $bookmarks, $parsed_args );
			}
		}
	}

	/**
	 * Filters the bookmarks list before it is echoed or returned.
	 *
	 * @since 2.5.0
	 *
	 * @param string $html The HTML list of bookmarks.
	 */
	$html = apply_filters( 'wp_list_bookmarks', $output );

	if ( $parsed_args['echo'] ) {
		echo $html;
	} else {
		return $html;
	}
}