Ticket #34292: 34292.4.diff

src/wp-admin/includes/admin-filters.php

@@ -43 +43 @@
 add_action( 'admin_head', 'wp_site_icon'             );
 add_action( 'admin_head', '_ipad_meta'               );
 
+// Prerendering.
+add_filter( 'admin_head', 'wp_browser_hints' );
+
 add_action( 'post_edit_form_tag', 'post_form_autocomplete_off' );
 
 add_action( 'update_option_home',          'update_home_siteurl', 10, 2 );

src/wp-includes/default-filters.php

@@ -235 +235 @@
 add_action( 'wp_head',             'wp_print_head_scripts',            9    );
 add_action( 'wp_head',             'wp_generator'                           );
 add_action( 'wp_head',             'rel_canonical'                          );
+add_action( 'wp_head',             'wp_browser_hints'                       );
 add_action( 'wp_head',             'wp_shortlink_wp_head',            10, 0 );
 add_action( 'wp_head',             'wp_site_icon',                    99    );
 add_action( 'wp_footer',           'wp_print_footer_scripts',         20    );

src/wp-includes/general-template.php

@@ -2755 +2755 @@
 }
 
 /**
+ * Makes sure browser hint array has unique values.
+ *
+ * @since 4.6.0
+ *
+ * @param array $urls Array of browser hints.
+ */
+function unique_browser_hints( $urls ) {
+        $seen = array();
+        foreach( $urls as $url ) {
+                if ( ! in_array( $url, $seen ) ) {
+                        array_push( $seen, $url );
+                }
+        }
+        return $seen;
+}
+
+/**
+ * Prints out brower hints for dns-prefetch, prerender, preconnect, etc.
+ *
+ * @since 4.6.0
+ */
+function wp_browser_hints() {
+
+        $default_urls = array(
+                array( 'preconnect', 's.w.org' ),
+        );
+
+        /**
+         * Filters domains and urls for browser hints.
+         *
+         * @since 4.6.0
+         *
+         * @param array $urls URL's to print for browser hints.
+         */
+        $urls           = apply_filters( 'browser_hints', $default_urls );
+        $prerender_urls = wp_prerender_posts();
+        $enqueued_hosts = wp_hint_scripts_styles();
+        $urls           = array_merge( $urls, $prerender_urls, $enqueued_hosts );
+
+        if ( is_admin() ) {
+                $admin_urls = prerender_admin_urls();
+                $urls       = array_merge( $urls, $admin_urls );
+        }
+
+        $urls = unique_browser_hints( $urls );
+
+        foreach ( $urls as $url ) {
+                if ( $url[0] === 'prerender' ) {
+                        $url[1] = esc_url( $url[1], array( 'http', 'https' ) );
+                } elseif ( $url[0] === 'dns-prefetch' || $url[0] === 'preconnect' ) {
+                        $url[1] = esc_url( untrailingslashit( $url[1] ), array( 'http', 'https' ) );
+                }
+                printf( "<link rel='%s' href='%s'>\r\n", $url[0], $url[1] );
+        }
+}
+
+/**
+ * Adds posts to be prerendered.
+ *
+ * @since 4.6.0
+ */
+function wp_prerender_posts() {
+        /**
+         * Filters the number of posts to prerender.
+         *
+         * @since 4.6.0
+         *
+         * @param int $prerender_count Number of posts to prerender.
+         */
+        $num_posts = apply_filters( 'prerender_count', 1 );
+
+        $posts_to_prerender = array();
+
+        if ( is_home() ) {
+
+                $count = 1;
+                while( have_posts() && $count <= $num_posts ) {
+                        the_post();
+                        array_push( $posts_to_prerender, array( 'prerender', get_the_permalink() ) );
+                        $count++;
+                }
+
+                rewind_posts();
+
+        } elseif ( is_single() ) {
+
+                $next_post = get_next_post();
+                $previous_post = get_previous_post();
+
+                if ( ! empty( $next_post ) ) {
+                        array_push( $posts_to_prerender, array( 'prerender', get_permalink( $next_post->ID ) ) );
+                }
+
+                if ( ! empty( $previous_post ) ) {
+                        array_push( $posts_to_prerender, array( 'prerender', get_permalink( $previous_post->ID ) ) );
+                }
+
+        }
+
+        return $posts_to_prerender;
+}
+
+/**
+ * Prerender pages in the admin that users are most likely to visit.
+ *
+ * @since 4.6.0
+ */
+function prerender_admin_urls() {
+
+        $default_urls = array(
+                array( 'prerender', admin_url( 'post-new.php' ) ),
+        );
+
+        /**
+         * Filters which admin pages will be prerendered.
+         *
+         * @since 4.6.0
+         *
+         * @param array $urls Admin URL's to prerender.
+         */
+        $urls = apply_filters( 'prerender_admin_pages', $default_urls );
+
+        return $urls;
+}
+
+/**
+ * Adds dns-prefetch for all scripts and styles enqueued from external hosts.
+ *
+ * @since 4.6.0
+ */
+function wp_hint_scripts_styles() {
+        global $wp_scripts, $wp_styles;
+
+        $unique_hosts = array();
+
+        foreach ( $wp_scripts->registered as $registered_script ) {
+                $this_host = parse_url( $registered_script->src, PHP_URL_HOST );
+                if ( ! in_array( $this_host, $unique_hosts ) && ! empty( $this_host ) && $this_host !== $_SERVER['SERVER_NAME'] ) {
+                        $unique_hosts[] = $this_host;
+                }
+        }
+
+        foreach ( $wp_styles->registered as $registered_style ) {
+                $this_host = parse_url( $registered_style->src, PHP_URL_HOST );
+                if ( ! in_array( $this_host, $unique_hosts ) && ! empty( $this_host ) && $this_host !== $_SERVER['SERVER_NAME'] ) {
+                        $unique_hosts[] = $this_host;
+                }
+        }
+
+        $unique_hosts = array_map( 'add_prefetch_attr', $unique_hosts );
+        return $unique_hosts;
+}
+
+/**
+ * Adds dns-prefetch to hosts of scripts and styles.
+ *
+ * @since 4.6.0
+ *
+ * @param array $hosts A hostname.
+ */
+function add_prefetch_attr( $host ) {
+        $host = array( 'dns-prefetch', $host );
+        return $host;
+}
+
+/**
  * Whether the user should have a WYSIWIG editor.
  *
  * Checks that the user requires a WYSIWIG editor and that the editor is

tests/phpunit/tests/general/template.php

@@ -345 +345 @@
                 $this->custom_logo_id  = $this->_make_attachment( $upload );
                 return $this->custom_logo_id;
         }
+
+        /**
+         * @ticket 34292
+         */
+        function test_wp_dns_prefetch() {
+                $this->assertEmpty( get_echo( 'wp_dns_prefetch' ) );
+
+                add_filter( 'dns_prefetch_domains', array( $this, '_add_dns_prefetch_domains' ) );
+
+                $expected = "<link rel='dns-prefetch' href='http://wordpress.org'>\r\n" .
+                            "<link rel='dns-prefetch' href='https://google.com'>\r\n" .
+                            "<link rel='dns-prefetch' href='//make.wordpress.org'>\r\n";
+
+                $this->assertEquals( $expected, get_echo( 'wp_dns_prefetch' ) );
+        }
+
+        function _add_dns_prefetch_domains( $domains ) {
+                $domains[] = 'http://wordpress.org';
+                $domains[] = 'https://google.com';
+                $domains[] = '//make.wordpress.org';
+
+                return $domains;
+        }
+
+        /**
+         * @ticket 34292
+         */
+        function test_wp_prerender() {
+                $this->assertEmpty( get_echo( 'wp_prerender' ) );
+
+                add_filter( 'prerender_urls', array( $this, '_add_prerender_urls' ) );
+
+                $expected = "<link rel='prerender' href='https://make.wordpress.org/great-again'>\r\n" .
+                            "<link rel='prerender' href='http://jobs.wordpress.net'>\r\n" .
+                            "<link rel='prerender' href='//core.trac.wordpress.org'>\r\n";
+
+                $this->assertEquals( $expected, get_echo( 'wp_prerender' ) );
+        }
+
+        function _add_prerender_urls( $urls ) {
+                $urls[] = 'https://make.wordpress.org/great-again';
+                $urls[] = 'http://jobs.wordpress.net';
+                $urls[] = '//core.trac.wordpress.org';
+
+                return $urls;
+        }
 }