WordPress/wp-includes/robots-template.php

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Robots: Introduce Robots API. This changeset introduces a filter-based Robots API, providing central control over the `robots` meta tag. * Introduces `wp_robots()` function which should be called anywhere a `robots` meta tag should be included. * Introduces `wp_robots` filter which allows adding or modifying directives for the `robots` meta tag. The `wp_robots()` function is entirely filter-based, i.e. if no filter is added to `wp_robots`, no directives will be present, and therefore the entire `robots` meta tag will be omitted. * Introduces the following `wp_robots` filter functions which replace similar existing functions that were manually rendering a `robots` meta tag: * `wp_robots_noindex()` replaces `noindex()`, which has been deprecated. * `wp_robots_no_robots()` replaces `wp_no_robots()`, which has been deprecated. * `wp_robots_sensitive_page()` replaces `wp_sensitive_page_meta()`, which has been deprecated. Its rendering of the `referrer` meta tag has been moved to another new function `wp_strict_cross_origin_referrer()`. Migration to the new functions is straightforward. For example, a call to `add_action( 'wp_head', 'wp_no_robots' )` should be replaced with `add_filter( 'wp_robots', 'wp_robots_no_robots' )`. Plugins and themes that render their own `robots` meta tags are encouraged to switch to rely on the `wp_robots` filter in order to use the central management layer now provided by WordPress core. Props adamsilverstein, flixos90, timothyblynjacobs, westonruter. See #51511. Built from https://develop.svn.wordpress.org/trunk@49992 git-svn-id: http://core.svn.wordpress.org/trunk@49693 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2021-01-21 02:37:00 +01:00
<?php
/**
* Robots template functions.
*
* @package WordPress
* @subpackage Robots
* @since 5.7.0
*/
/**
* Displays the robots meta tag as necessary.
*
* Gathers robots directives to include for the current context, using the
* {@see 'wp_robots'} filter. The directives are then sanitized, and the
* robots meta tag is output if there is at least one relevant directive.
*
* @since 5.7.0
*/
function wp_robots() {
/**
* Filters the directives to be included in the 'robots' meta tag.
*
* The meta tag will only be included as necessary.
*
* @since 5.7.0
*
* @param array $robots Associative array of directives. Every key must be the name of the directive, and the
* corresponding value must either be a string to provide as value for the directive or a
* boolean `true` if it is a boolean directive, i.e. without a value.
*/
$robots = apply_filters( 'wp_robots', array() );
// Don't allow mutually exclusive directives.
if ( ! empty( $robots['follow'] ) ) {
unset( $robots['nofollow'] );
}
if ( ! empty( $robots['nofollow'] ) ) {
unset( $robots['follow'] );
}
if ( ! empty( $robots['archive'] ) ) {
unset( $robots['noarchive'] );
}
if ( ! empty( $robots['noarchive'] ) ) {
unset( $robots['archive'] );
}
$robots_strings = array();
foreach ( $robots as $directive => $value ) {
if ( is_string( $value ) ) {
// If a string value, include it as value for the directive.
$robots_strings[] = "{$directive}:{$value}";
} elseif ( $value ) {
// Otherwise, include the directive if it is truthy.
$robots_strings[] = $directive;
}
}
if ( empty( $robots_strings ) ) {
return;
}
echo "<meta name='robots' content='" . esc_attr( implode( ', ', $robots_strings ) ) . "' />\n";
}
/**
* Adds noindex to the robots meta tag if required by the site configuration.
*
* If a blog is marked as not being public then noindex will be output to
* tell web robots not to index the page content. Add this to the
* {@see 'wp_robots'} filter.
*
* Typical usage is as a {@see 'wp_robots'} callback:
*
* add_filter( 'wp_robots', 'wp_robots_noindex' );
*
* @since 5.7.0
* @see wp_robots_no_robots()
*
* @param array $robots Associative array of robots directives.
* @return array Filtered robots directives.
*/
function wp_robots_noindex( array $robots ) {
if ( ! get_option( 'blog_public' ) ) {
return wp_robots_no_robots( $robots );
}
return $robots;
}
/**
* Adds noindex to the robots meta tag.
*
* This directive tells web robots not to index the page content.
*
* Typical usage is as a {@see 'wp_robots'} callback:
*
* add_filter( 'wp_robots', 'wp_robots_no_robots' );
*
* @since 5.7.0
*
* @param array $robots Associative array of robots directives.
* @return array Filtered robots directives.
*/
function wp_robots_no_robots( array $robots ) {
$robots['noindex'] = true;
if ( get_option( 'blog_public' ) ) {
$robots['follow'] = true;
} else {
$robots['nofollow'] = true;
}
return $robots;
}
/**
* Adds noindex and noarchive to the robots meta tag.
*
* This directive tells web robots not to index or archive the page content and
* is recommended to be used for sensitive pages.
*
* Typical usage is as a {@see 'wp_robots'} callback:
*
* add_filter( 'wp_robots', 'wp_robots_sensitive_page' );
*
* @since 5.7.0
*
* @param array $robots Associative array of robots directives.
* @return array Filtered robots directives.
*/
function wp_robots_sensitive_page( array $robots ) {
$robots['noindex'] = true;
$robots['noarchive'] = true;
return $robots;
}
/**
* Adds 'max-image-preview:large' to the robots meta tag.
*
* This directive tells web robots that large image previews are allowed to be
* displayed, e.g. in search engines, unless the blog is marked as not being public.
*
* Typical usage is as a {@see 'wp_robots'} callback:
*
* add_filter( 'wp_robots', 'wp_robots_max_image_preview_large' );
*
* @since 5.7.0
*
* @param array $robots Associative array of robots directives.
* @return array Filtered robots directives.
*/
function wp_robots_max_image_preview_large( array $robots ) {
if ( get_option( 'blog_public' ) ) {
$robots['max-image-preview'] = 'large';
}
return $robots;
}