Implement core template loader overrides to rely on wp_template posts…

… instead.
WordPress · Sep 27, 2019 · 4c93d15 · 4c93d15
1 parent 394da9e
commit 4c93d15
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diff --git a/lib/load.php b/lib/load.php
@@ -41,6 +41,7 @@
 
 require dirname( __FILE__ ) . '/blocks.php';
 require dirname( __FILE__ ) . '/templates.php';
+require dirname( __FILE__ ) . '/template-loader.php';
 require dirname( __FILE__ ) . '/client-assets.php';
 require dirname( __FILE__ ) . '/demo.php';
 require dirname( __FILE__ ) . '/widgets.php';

diff --git a/lib/template-canvas.php b/lib/template-canvas.php
@@ -0,0 +1,23 @@
+<?php
+/**
+ * Template canvas file to render the current 'wp_template'.
+ *
+ * @package gutenberg
+ */
+
+?>
+<!DOCTYPE html>
+<html <?php language_attributes(); ?>>
+<head>
+	<meta charset="<?php bloginfo( 'charset' ); ?>" />
+	<?php wp_head(); ?>
+</head>
+
+<body <?php body_class(); ?>>
+<?php wp_body_open(); ?>
+
+<?php gutenberg_render_the_template(); ?>
+
+<?php wp_footer(); ?>
+</body>
+</html>
diff --git a/lib/template-loader.php b/lib/template-loader.php
@@ -0,0 +1,162 @@
+<?php
+/**
+ * Block template loader functions.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Adds necessary filters to use 'wp_template' posts instead of theme template files.
+ */
+function gutenberg_add_template_loader_filters() {
+	if ( ! post_type_exists( 'wp_template' ) ) {
+		return;
+	}
+
+	/**
+	 * Array of all overrideable default template types.
+	 *
+	 * @see get_query_template
+	 *
+	 * @var array
+	 */
+	$template_types = array(
+		'index',
+		'404',
+		'archive',
+		'author',
+		'category',
+		'tag',
+		'taxonomy',
+		'date',
+		// Skip 'embed' for now because it is not a regular template type.
+		'home',
+		'frontpage',
+		'privacypolicy',
+		'page',
+		'search',
+		'single',
+		'singular',
+		'attachment',
+	);
+	foreach ( $template_types as $template_type ) {
+		add_filter( $template_type . '_template', 'gutenberg_override_query_template', 20, 3 );
+	}
+
+	add_filter( 'template_include', 'gutenberg_find_template', 20 );
+}
+add_action( 'wp_loaded', 'gutenberg_add_template_loader_filters' );
+
+/**
+ * Filters into the "{$type}_template" hooks to record the current template hierarchy.
+ *
+ * The method returns an empty result for every template so that a 'wp_template' post
+ * is used instead.
+ *
+ * @see gutenberg_find_template
+ *
+ * @param string $template  Path to the template. See locate_template().
+ * @param string $type      Sanitized filename without extension.
+ * @param array  $templates A list of template candidates, in descending order of priority.
+ * @return string Empty string to ensure template file is considered not found.
+ */
+function gutenberg_override_query_template( $template, $type, array $templates = array() ) {
+	global $_wp_current_template_hierarchy;
+
+	if ( ! is_array( $_wp_current_template_hierarchy ) ) {
+		$_wp_current_template_hierarchy = $templates;
+	} else {
+		$_wp_current_template_hierarchy = array_merge( $_wp_current_template_hierarchy, $templates );
+	}
+
+	return '';
+}
+
+/**
+ * Find the correct 'wp_template' post for the current hierarchy and return the path
+ * to the canvas file that will render it.
+ *
+ * @param string $template_file Original template file. Will be overridden.
+ * @return string Path to the canvas file to include.
+ */
+function gutenberg_find_template( $template_file ) {
+	global $_wp_current_template_post, $_wp_current_template_hierarchy;
+
+	// Bail if no relevant template hierarchy was determined, or if the template file
+	// was overridden another way.
+	if ( ! $_wp_current_template_hierarchy || $template_file ) {
+		return $template_file;
+	}
+
+	$slugs = array_map(
+		'gutenberg_strip_php_suffix',
+		$_wp_current_template_hierarchy
+	);
+
+	// Find most specific 'wp_template' post matching the hierarchy.
+	$template_query = new WP_Query(
+		array(
+			'post_type'      => 'wp_template',
+			'post_status'    => 'publish',
+			'post_name__in'  => $slugs,
+			'orderby'        => 'post_name__in',
+			'posts_per_page' => 1,
+		)
+	);
+
+	if ( $template_query->have_posts() ) {
+		$template_posts            = $template_query->get_posts();
+		$_wp_current_template_post = $template_posts[0];
+	}
+
+	// Add extra hooks for template canvas.
+	add_action( 'wp_head', 'gutenberg_viewport_meta_tag', 0 );
+
+	// This file will be included instead of the theme's template file.
+	return gutenberg_dir_path() . 'lib/template-canvas.php';
+}
+
+/**
+ * Renders the markup for the current template.
+ */
+function gutenberg_render_the_template() {
+	global $_wp_current_template_post;
+
+	if ( ! $_wp_current_template_post || 'wp_template' !== $_wp_current_template_post->post_type ) {
+		echo '<h1>' . esc_html__( 'No matching template found', 'gutenberg' ) . '</h1>';
+		return;
+	}
+
+	$content = $_wp_current_template_post->post_content;
+
+	$content = do_blocks( $content );
+	$content = wptexturize( $content );
+	$content = str_replace( ']]>', ']]&gt;', $content );
+
+	// Wrap block template in .wp-site-blocks to allow for specific descendant styles
+	// (e.g. `.wp-site-blocks > *`).
+	echo '<div class="wp-site-blocks">';
+	echo $content; // phpcs:ignore WordPress.Security.EscapeOutput
+	echo '</div>';
+}
+
+/**
+ * Renders a 'viewport' meta tag.
+ *
+ * This is hooked into {@see 'wp_head'} to decouple its output from the default template canvas.
+ */
+function gutenberg_viewport_meta_tag() {
+	echo '<meta name="viewport" content="width=device-width, initial-scale=1" />' . "\n";
+}
+
+/**
+ * Strips .php suffix from template file names.
+ *
+ * @access private
+ *
+ * @param string $template_file Template file name.
+ * @return string Template file name without extension.
+ */
+function gutenberg_strip_php_suffix( $template_file ) {
+	return preg_replace( '/\.php$/', '', $template_file );
+}
diff --git a/lib/templates.php b/lib/templates.php
@@ -65,3 +65,32 @@ function gutenberg_grant_template_caps( array $allcaps ) {
 	return $allcaps;
 }
 add_filter( 'user_has_cap', 'gutenberg_grant_template_caps' );
+
+/**
+ * Filters capabilities to prevent deletion of the 'wp_template' post with slug 'index'.
+ *
+ * Similar to today's themes, this template should always exist.
+ *
+ * @param array  $caps    Array of the user's capabilities.
+ * @param string $cap     Capability name.
+ * @param int    $user_id The user ID.
+ * @param array  $args    Adds the context to the cap. Typically the object ID.
+ * @return array Filtered $caps.
+ */
+function gutenberg_prevent_index_template_deletion( $caps, $cap, $user_id, $args ) {
+	if ( 'delete_post' !== $cap || ! isset( $args[0] ) ) {
+		return $caps;
+	}
+
+	$post = get_post( $args[0] );
+	if ( ! $post || 'wp_template' !== $post->post_type ) {
+		return $caps;
+	}
+
+	if ( 'index' === $post->post_name ) {
+		$caps[] = 'do_not_allow';
+	}
+
+	return $caps;
+}
+add_filter( 'map_meta_cap', 'gutenberg_prevent_index_template_deletion', 10, 4 );