Introduce a new means of outputting a `<title>` tag in the theme head. Requires a theme to add support by calling `add_theme_support( 'title-tag' )`. This is the first step in adding a more robust means of generating and outputting the title tag.

See #18548.
Props obenland, chrisbliss18, joostdevalk.


Built from https://develop.svn.wordpress.org/trunk@30074


git-svn-id: http://core.svn.wordpress.org/trunk@30074 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/default-filters.php

@@ -196,6 +196,7 @@ add_filter( 'title_save_pre',           'trim'                                );
 add_filter( 'http_request_host_is_external', 'allowed_http_request_hosts', 10, 2 );
 
 // Actions
+add_action( 'wp_head',             '_wp_render_title_tag',            1     );
 add_action( 'wp_head',             'wp_enqueue_scripts',              1     );
 add_action( 'wp_head',             'feed_links',                      2     );
 add_action( 'wp_head',             'feed_links_extra',                3     );

wp-includes/general-template.php

@@ -730,6 +730,25 @@ function get_bloginfo( $show = '', $filter = 'raw' ) {
 	return $output;
 }
 
+/**
+ * Display <title> tag with contents.
+ *
+ * @since 4.1.0
+ * @access private
+ */
+function _wp_render_title_tag() {
+	if ( ! current_theme_supports( 'title-tag' ) ) {
+		return;
+	}
+
+	// This can only work internally on wp_head.
+	if ( ! did_action( 'wp_head' ) && ! doing_action( 'wp_head' ) ) {
+		return;
+	}
+
+	echo '<title>' . wp_title( '|', false, 'right' ) . "</title>\n";
+}
+
 /**
  * Display or retrieve page title for all areas of blog.
  *
@@ -753,7 +772,7 @@ function get_bloginfo( $show = '', $filter = 'raw' ) {
  * @return string|null String on retrieve, null when displaying.
  */
 function wp_title($sep = '&raquo;', $display = true, $seplocation = '') {
-	global $wp_locale;
+	global $wp_locale, $page, $paged;
 
 	$m = get_query_var('m');
 	$year = get_query_var('year');
@@ -853,6 +872,19 @@ function wp_title($sep = '&raquo;', $display = true, $seplocation = '') {
 		$title = $prefix . implode( " $sep ", $title_array );
 	}
 
+	if ( current_theme_supports( 'title-tag' ) && ! is_feed() ) {
+		$title .= get_bloginfo( 'name', 'display' );
+
+		$site_description = get_bloginfo( 'description', 'display' );
+		if ( $site_description && ( is_home() || is_front_page() ) ) {
+			$title .= " $sep $site_description";
+		}
+
+		if ( ( $paged >= 2 || $page >= 2 ) && ! is_404() ) {
+			$title .= " $sep " . sprintf( __( 'Page %s' ), max( $paged, $page ) );
+		}
+	}
+
 	/**
 	 * Filter the text of the page title.
 	 *

wp-includes/theme.php

@@ -1611,6 +1611,15 @@ function add_theme_support( $feature ) {
 				define( 'BACKGROUND_IMAGE', $args[0]['default-image'] );
 
 			break;
+
+		// Ensure that 'title-tag' is accessible in the admin.
+		case 'title-tag' :
+			// Can be called in functions.php but must happen before wp_loaded, i.e. not in header.php.
+			if ( did_action( 'wp_loaded' ) ) {
+				_doing_it_wrong( "add_theme_support( 'title-tag' )", sprintf( _x( 'You need to add theme support before %s.', 'action name' ), '<code>wp_loaded</code>' ), '4.1.0' );
+
+				return false;
+			}
 	}
 
 	$_wp_theme_features[ $feature ] = $args;
@@ -1763,6 +1772,14 @@ function current_theme_supports( $feature ) {
 	if ( !isset( $_wp_theme_features[$feature] ) )
 		return false;
 
+	if ( 'title-tag' == $feature ) {
+		// Don't confirm support unless called internally.
+		$trace = debug_backtrace();
+		if ( ! in_array( $trace[1]['function'], array( '_wp_render_title_tag', 'wp_title' ) ) ) {
+			return false;
+		}
+	}
+
 	// If no args passed then no extra checks need be performed
 	if ( func_num_args() <= 1 )
 		return true;

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.1-alpha-30073';
+$wp_version = '4.1-alpha-30074';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.