Changeset 52062 for trunk/src/wp-includes/block-template-utils.php

Timestamp:

11/08/2021 11:09:53 PM (3 years ago)

Author:

noisysocks

Message:

Editor: Add block theme infrastructure

Adds the required infrastructure to render block-based themes. This is sourced
from the Gutenberg plugin.

Fixes #54335.
Props bernhard-reiter, youknowriad, ntsekouras, hellofromtonya.

File:

• trunk/src/wp-includes/block-template-utils.php (modified) (11 diffs)

trunk/src/wp-includes/block-template-utils.php

@@ -1 +1 @@
 <?php
 /**
- * Utilities used to fetch and create templates.
+ * Utilities used to fetch and create templates and template parts.
  *
  * @package WordPress
@@ -7 +7 @@
  */
 
+// Define constants for supported wp_template_part_area taxonomy.
+if ( ! defined( 'WP_TEMPLATE_PART_AREA_HEADER' ) ) {
+    define( 'WP_TEMPLATE_PART_AREA_HEADER', 'header' );
+}
+if ( ! defined( 'WP_TEMPLATE_PART_AREA_FOOTER' ) ) {
+    define( 'WP_TEMPLATE_PART_AREA_FOOTER', 'footer' );
+}
+if ( ! defined( 'WP_TEMPLATE_PART_AREA_SIDEBAR' ) ) {
+    define( 'WP_TEMPLATE_PART_AREA_SIDEBAR', 'sidebar' );
+}
+if ( ! defined( 'WP_TEMPLATE_PART_AREA_UNCATEGORIZED' ) ) {
+    define( 'WP_TEMPLATE_PART_AREA_UNCATEGORIZED', 'uncategorized' );
+}
+
+/**
+ * Returns a filtered list of allowed area values for template parts.
+ *
+ * @since 5.9.0
+ *
+ * @return array The supported template part area values.
+ */
+function get_allowed_block_template_part_areas() {
+    $default_area_definitions = array(
+        array(
+            'area'        => WP_TEMPLATE_PART_AREA_UNCATEGORIZED,
+            'label'       => __( 'General' ),
+            'description' => __(
+                'General templates often perform a specific role like displaying post content, and are not tied to any particular area.'
+            ),
+            'icon'        => 'layout',
+            'area_tag'    => 'div',
+        ),
+        array(
+            'area'        => WP_TEMPLATE_PART_AREA_HEADER,
+            'label'       => __( 'Header' ),
+            'description' => __(
+                'The Header template defines a page area that typically contains a title, logo, and main navigation.'
+            ),
+            'icon'        => 'header',
+            'area_tag'    => 'header',
+        ),
+        array(
+            'area'        => WP_TEMPLATE_PART_AREA_FOOTER,
+            'label'       => __( 'Footer' ),
+            'description' => __(
+                'The Footer template defines a page area that typically contains site credits, social links, or any other combination of blocks.'
+            ),
+            'icon'        => 'footer',
+            'area_tag'    => 'footer',
+        ),
+    );
+
+    /**
+     * Filters the list of allowed template part area values.
+     *
+     * @since 5.9.0
+     *
+     * @param array $default_areas An array of supported area objects.
+     */
+    return apply_filters( 'default_wp_template_part_areas', $default_area_definitions );
+}
+
+
+/**
+ * Returns a filtered list of default template types, containing their
+ * localized titles and descriptions.
+ *
+ * @since 5.9.0
+ *
+ * @return array The default template types.
+ */
+function get_default_block_template_types() {
+    $default_template_types = array(
+        'index'          => array(
+            'title'       => _x( 'Index', 'Template name' ),
+            'description' => __( 'The default template used when no other template is available. This is a required template in WordPress.' ),
+        ),
+        'home'           => array(
+            'title'       => _x( 'Home', 'Template name' ),
+            'description' => __( 'Template used for the main page that displays blog posts. This is the front page by default in WordPress. If a static front page is set, this is the template used for the page that contains the latest blog posts.' ),
+        ),
+        'front-page'     => array(
+            'title'       => _x( 'Front Page', 'Template name' ),
+            'description' => __( 'Template used to render the front page of the site, whether it displays blog posts or a static page. The front page template takes precedence over the "Home" template.' ),
+        ),
+        'singular'       => array(
+            'title'       => _x( 'Singular', 'Template name' ),
+            'description' => __( 'Template used for displaying single views of the content. This template is a fallback for the Single, Post, and Page templates, which take precedence when they exist.' ),
+        ),
+        'single'         => array(
+            'title'       => _x( 'Single Post', 'Template name' ),
+            'description' => __( 'Template used to display a single blog post.' ),
+        ),
+        'page'           => array(
+            'title'       => _x( 'Page', 'Template name' ),
+            'description' => __( 'Template used to display individual pages.' ),
+        ),
+        'archive'        => array(
+            'title'       => _x( 'Archive', 'Template name' ),
+            'description' => __( 'The archive template displays multiple entries at once. It is used as a fallback for the Category, Author, and Date templates, which take precedence when they are available.' ),
+        ),
+        'author'         => array(
+            'title'       => _x( 'Author', 'Template name' ),
+            'description' => __( 'Archive template used to display a list of posts from a single author.' ),
+        ),
+        'category'       => array(
+            'title'       => _x( 'Category', 'Template name' ),
+            'description' => __( 'Archive template used to display a list of posts from the same category.' ),
+        ),
+        'taxonomy'       => array(
+            'title'       => _x( 'Taxonomy', 'Template name' ),
+            'description' => __( 'Archive template used to display a list of posts from the same taxonomy.' ),
+        ),
+        'date'           => array(
+            'title'       => _x( 'Date', 'Template name' ),
+            'description' => __( 'Archive template used to display a list of posts from a specific date.' ),
+        ),
+        'tag'            => array(
+            'title'       => _x( 'Tag', 'Template name' ),
+            'description' => __( 'Archive template used to display a list of posts with a given tag.' ),
+        ),
+        'attachment'     => array(
+            'title'       => __( 'Media' ),
+            'description' => __( 'Template used to display individual media items or attachments.' ),
+        ),
+        'search'         => array(
+            'title'       => _x( 'Search', 'Template name' ),
+            'description' => __( 'Template used to display search results.' ),
+        ),
+        'privacy-policy' => array(
+            'title'       => __( 'Privacy Policy' ),
+            'description' => '',
+        ),
+        '404'            => array(
+            'title'       => _x( '404', 'Template name' ),
+            'description' => __( 'Template shown when no content is found.' ),
+        ),
+    );
+
+    /**
+     * Filters the list of template types.
+     *
+     * @since 5.9.0
+     *
+     * @param array $default_template_types An array of template types, formatted as [ slug => [ title, description ] ].
+     */
+    return apply_filters( 'default_template_types', $default_template_types );
+}
+
+/**
+ * Checks whether the input 'area' is a supported value.
+ * Returns the input if supported, otherwise returns the 'uncategorized' value.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param string $type Template part area name.
+ *
+ * @return string Input if supported, else the uncategorized value.
+ */
+function _filter_block_template_part_area( $type ) {
+    $allowed_areas = array_map(
+        static function ( $item ) {
+            return $item['area'];
+        },
+        get_allowed_block_template_part_areas()
+    );
+    if ( in_array( $type, $allowed_areas, true ) ) {
+        return $type;
+    }
+
+    $warning_message = sprintf(
+        /* translators: %1$s: Template area type, %2$s: the uncategorized template area value. */
+        __( '"%1$s" is not a supported wp_template_part area value and has been added as "%2$s".' ),
+        $type,
+        WP_TEMPLATE_PART_AREA_UNCATEGORIZED
+    );
+    trigger_error( $warning_message, E_USER_NOTICE );
+    return WP_TEMPLATE_PART_AREA_UNCATEGORIZED;
+}
+
+/**
+ * Finds all nested template part file paths in a theme's directory.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param string $base_directory The theme's file path.
+ * @return array $path_list A list of paths to all template part files.
+ */
+function _get_block_templates_paths( $base_directory ) {
+    $path_list = array();
+    if ( file_exists( $base_directory ) ) {
+        $nested_files      = new RecursiveIteratorIterator( new RecursiveDirectoryIterator( $base_directory ) );
+        $nested_html_files = new RegexIterator( $nested_files, '/^.+\.html$/i', RecursiveRegexIterator::GET_MATCH );
+        foreach ( $nested_html_files as $path => $file ) {
+            $path_list[] = $path;
+        }
+    }
+    return $path_list;
+}
+
+/**
+ * Retrieves the template file from the theme for a given slug.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param string $template_type wp_template or wp_template_part.
+ * @param string $slug template slug.
+ *
+ * @return array|null Template.
+ */
+function _get_block_template_file( $template_type, $slug ) {
+    if ( 'wp_template' !== $template_type && 'wp_template_part' !== $template_type ) {
+        return null;
+    }
+
+    $template_base_paths = array(
+        'wp_template'      => 'block-templates',
+        'wp_template_part' => 'block-template-parts',
+    );
+    $themes              = array(
+        get_stylesheet() => get_stylesheet_directory(),
+        get_template()   => get_template_directory(),
+    );
+    foreach ( $themes as $theme_slug => $theme_dir ) {
+        $file_path = $theme_dir . '/' . $template_base_paths[ $template_type ] . '/' . $slug . '.html';
+        if ( file_exists( $file_path ) ) {
+            $new_template_item = array(
+                'slug'  => $slug,
+                'path'  => $file_path,
+                'theme' => $theme_slug,
+                'type'  => $template_type,
+            );
+
+            if ( 'wp_template_part' === $template_type ) {
+                return _add_block_template_part_area_info( $new_template_item );
+            }
+
+            if ( 'wp_template' === $template_type ) {
+                return _add_block_template_info( $new_template_item );
+            }
+
+            return $new_template_item;
+        }
+    }
+
+    return null;
+}
+
+/**
+ * Retrieves the template files from  the theme.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param string $template_type wp_template or wp_template_part.
+ *
+ * @return array Template.
+ */
+function _get_block_templates_files( $template_type ) {
+    if ( 'wp_template' !== $template_type && 'wp_template_part' !== $template_type ) {
+        return null;
+    }
+
+    $template_base_paths = array(
+        'wp_template'      => 'block-templates',
+        'wp_template_part' => 'block-template-parts',
+    );
+    $themes              = array(
+        get_stylesheet() => get_stylesheet_directory(),
+        get_template()   => get_template_directory(),
+    );
+
+    $template_files = array();
+    foreach ( $themes as $theme_slug => $theme_dir ) {
+        $theme_template_files = _get_block_templates_paths( $theme_dir . '/' . $template_base_paths[ $template_type ] );
+        foreach ( $theme_template_files as $template_file ) {
+            $template_base_path = $template_base_paths[ $template_type ];
+            $template_slug      = substr(
+                $template_file,
+                // Starting position of slug.
+                strpos( $template_file, $template_base_path . DIRECTORY_SEPARATOR ) + 1 + strlen( $template_base_path ),
+                // Subtract ending '.html'.
+                -5
+            );
+            $new_template_item = array(
+                'slug'  => $template_slug,
+                'path'  => $template_file,
+                'theme' => $theme_slug,
+                'type'  => $template_type,
+            );
+
+            if ( 'wp_template_part' === $template_type ) {
+                $template_files[] = _add_block_template_part_area_info( $new_template_item );
+            }
+
+            if ( 'wp_template' === $template_type ) {
+                $template_files[] = _add_block_template_info( $new_template_item );
+            }
+        }
+    }
+
+    return $template_files;
+}
+
+/**
+ * Attempts to add custom template information to the template item.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param array $template_item Template to add information to (requires 'slug' field).
+ * @return array Template
+ */
+function _add_block_template_info( $template_item ) {
+    if ( ! WP_Theme_JSON_Resolver::theme_has_support() ) {
+        return $template_item;
+    }
+
+    $theme_data = WP_Theme_JSON_Resolver::get_theme_data()->get_custom_templates();
+    if ( isset( $theme_data[ $template_item['slug'] ] ) ) {
+        $template_item['title']     = $theme_data[ $template_item['slug'] ]['title'];
+        $template_item['postTypes'] = $theme_data[ $template_item['slug'] ]['postTypes'];
+    }
+
+    return $template_item;
+}
+
+/**
+ * Attempts to add the template part's area information to the input template.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param array $template_info Template to add information to (requires 'type' and 'slug' fields).
+ *
+ * @return array Template.
+ */
+function _add_block_template_part_area_info( $template_info ) {
+    if ( WP_Theme_JSON_Resolver::theme_has_support() ) {
+        $theme_data = WP_Theme_JSON_Resolver::get_theme_data()->get_template_parts();
+    }
+
+    if ( isset( $theme_data[ $template_info['slug'] ]['area'] ) ) {
+        $template_info['title'] = $theme_data[ $template_info['slug'] ]['title'];
+        $template_info['area']  = _filter_block_template_part_area( $theme_data[ $template_info['slug'] ]['area'] );
+    } else {
+        $template_info['area'] = WP_TEMPLATE_PART_AREA_UNCATEGORIZED;
+    }
+
+    return $template_info;
+}
+
+/**
+ * Returns an array containing the references of
+ * the passed blocks and their inner blocks.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param array $blocks array of blocks.
+ *
+ * @return array block references to the passed blocks and their inner blocks.
+ */
+function _flatten_blocks( &$blocks ) {
+    $all_blocks = array();
+    $queue      = array();
+    foreach ( $blocks as &$block ) {
+        $queue[] = &$block;
+    }
+
+    while ( count( $queue ) > 0 ) {
+        $block = &$queue[0];
+        array_shift( $queue );
+        $all_blocks[] = &$block;
+
+        if ( ! empty( $block['innerBlocks'] ) ) {
+            foreach ( $block['innerBlocks'] as &$inner_block ) {
+                $queue[] = &$inner_block;
+            }
+        }
+    }
+
+    return $all_blocks;
+}
+
+/**
+ * Parses wp_template content and injects the current theme's
+ * stylesheet as a theme attribute into each wp_template_part
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param string $template_content serialized wp_template content.
+ *
+ * @return string Updated wp_template content.
+ */
+function _inject_theme_attribute_in_block_template_content( $template_content ) {
+    $has_updated_content = false;
+    $new_content         = '';
+    $template_blocks     = parse_blocks( $template_content );
+
+    $blocks = _flatten_blocks( $template_blocks );
+    foreach ( $blocks as &$block ) {
+        if (
+            'core/template-part' === $block['blockName'] &&
+            ! isset( $block['attrs']['theme'] )
+        ) {
+            $block['attrs']['theme'] = wp_get_theme()->get_stylesheet();
+            $has_updated_content     = true;
+        }
+    }
+
+    if ( $has_updated_content ) {
+        foreach ( $template_blocks as &$block ) {
+            $new_content .= serialize_block( $block );
+        }
+
+        return $new_content;
+    }
+
+    return $template_content;
+}
+
+/**
+ * Build a unified template object based on a theme file.
+ *
+ * @access private
+ * @since 5.9.0
+ *
+ * @param array $template_file Theme file.
+ * @param array $template_type wp_template or wp_template_part.
+ *
+ * @return WP_Block_Template Template.
+ */
+function _build_block_template_result_from_file( $template_file, $template_type ) {
+    $default_template_types = get_default_block_template_types();
+    $template_content       = file_get_contents( $template_file['path'] );
+    $theme                  = wp_get_theme()->get_stylesheet();
+
+    $template                 = new WP_Block_Template();
+    $template->id             = $theme . '//' . $template_file['slug'];
+    $template->theme          = $theme;
+    $template->content        = _inject_theme_attribute_in_block_template_content( $template_content );
+    $template->slug           = $template_file['slug'];
+    $template->source         = 'theme';
+    $template->type           = $template_type;
+    $template->title          = ! empty( $template_file['title'] ) ? $template_file['title'] : $template_file['slug'];
+    $template->status         = 'publish';
+    $template->has_theme_file = true;
+    $template->is_custom      = true;
+
+    if ( 'wp_template' === $template_type && isset( $default_template_types[ $template_file['slug'] ] ) ) {
+        $template->description = $default_template_types[ $template_file['slug'] ]['description'];
+        $template->title       = $default_template_types[ $template_file['slug'] ]['title'];
+        $template->is_custom   = false;
+    }
+
+    if ( 'wp_template' === $template_type && isset( $template_file['postTypes'] ) ) {
+        $template->post_types = $template_file['postTypes'];
+    }
+
+    if ( 'wp_template_part' === $template_type && isset( $template_file['area'] ) ) {
+        $template->area = $template_file['area'];
+    }
+
+    return $template;
+}
+
 /**
  * Build a unified template object based a post Object.
  *
  * @access private
- * @since 5.8.0
+ * @since 5.9.0
  *
  * @param WP_Post $post Template post.
@@ -17 +488 @@
  * @return WP_Block_Template|WP_Error Template.
  */
-function _build_template_result_from_post( $post ) {
-    $terms = get_the_terms( $post, 'wp_theme' );
+function _build_block_template_result_from_post( $post ) {
+    $default_template_types = get_default_block_template_types();
+    $terms                  = get_the_terms( $post, 'wp_theme' );
 
     if ( is_wp_error( $terms ) ) {
@@ -28 +500 @@
     }
 
-    $theme = $terms[0]->name;
+    $theme          = $terms[0]->name;
+    $has_theme_file = wp_get_theme()->get_stylesheet() === $theme &&
+        null !== _get_block_template_file( $post->post_type, $post->post_name );
 
     $template                 = new WP_Block_Template();
@@ -41 +515 @@
     $template->title          = $post->post_title;
     $template->status         = $post->post_status;
-    $template->has_theme_file = false;
+    $template->has_theme_file = $has_theme_file;
+    $template->is_custom      = true;
+
+    if ( 'wp_template' === $post->post_type && isset( $default_template_types[ $template->slug ] ) ) {
+        $template->is_custom = false;
+    }
+
+    if ( 'wp_template_part' === $post->post_type ) {
+        $type_terms = get_the_terms( $post, 'wp_template_part_area' );
+        if ( ! is_wp_error( $type_terms ) && false !== $type_terms ) {
+            $template->area = $type_terms[0]->name;
+        }
+    }
 
     return $template;
@@ -54 +540 @@
  *     Optional. Arguments to retrieve templates.
  *
- *     @type array  $slug__in List of slugs to include.
- *     @type int    $wp_id Post ID of customized template.
+ *     @type array  $slug__in  List of slugs to include.
+ *     @type int    $wp_id     Post ID of customized template.
+ *     @type string $area      A 'wp_template_part_area' taxonomy value to filter by (for wp_template_part template type only).
+ *     @type string $post_type Post type to get the templates for.
  * }
- * @param string $template_type Optional. The template type (post type). Default 'wp_template'.
- * @return WP_Block_Template[] Block template objects.
+ * @param array $template_type wp_template or wp_template_part.
+ *
+ * @return array Templates.
  */
 function get_block_templates( $query = array(), $template_type = 'wp_template' ) {
+    /**
+     * Filters the block templates array before the query takes place.
+     *
+     * Return a non-null value to bypass the WordPress queries.
+     *
+     * @since 5.9
+     *
+     * @param WP_Block_Template[]|null $block_templates Return an array of block templates to short-circuit the default query,
+     *                                                  or null to allow WP to run it's normal queries.
+     * @param array $query {
+     *     Optional. Arguments to retrieve templates.
+     *
+     *     @type array  $slug__in List of slugs to include.
+     *     @type int    $wp_id Post ID of customized template.
+     *     @type string $post_type Post type to get the templates for.
+     * }
+     * @param array $template_type wp_template or wp_template_part.
+     */
+    $templates = apply_filters( 'pre_get_block_templates', null, $query, $template_type );
+    if ( ! is_null( $templates ) ) {
+        return $templates;
+    }
+
+    $post_type     = isset( $query['post_type'] ) ? $query['post_type'] : '';
     $wp_query_args = array(
         'post_status'    => array( 'auto-draft', 'draft', 'publish' ),
@@ -75 +588 @@
     );
 
+    if ( 'wp_template_part' === $template_type && isset( $query['area'] ) ) {
+        $wp_query_args['tax_query'][]           = array(
+            'taxonomy' => 'wp_template_part_area',
+            'field'    => 'name',
+            'terms'    => $query['area'],
+        );
+        $wp_query_args['tax_query']['relation'] = 'AND';
+    }
+
     if ( isset( $query['slug__in'] ) ) {
         $wp_query_args['post_name__in'] = $query['slug__in'];
     }
 
-    // This is only needed for the regular templates CPT listing and editor.
+    // This is only needed for the regular templates/template parts CPT listing and editor.
     if ( isset( $query['wp_id'] ) ) {
         $wp_query_args['p'] = $query['wp_id'];
@@ -89 +611 @@
     $query_result   = array();
     foreach ( $template_query->posts as $post ) {
-        $template = _build_template_result_from_post( $post );
-
-        if ( ! is_wp_error( $template ) ) {
-            $query_result[] = $template;
-        }
-    }
-
-    return $query_result;
+        $template = _build_block_template_result_from_post( $post );
+
+        if ( is_wp_error( $template ) ) {
+            continue;
+        }
+
+        if ( $post_type && ! $template->is_custom ) {
+            continue;
+        }
+
+        $query_result[] = $template;
+    }
+
+    if ( ! isset( $query['wp_id'] ) ) {
+        $template_files = _get_block_templates_files( $template_type );
+        foreach ( $template_files as $template_file ) {
+            $template = _build_block_template_result_from_file( $template_file, $template_type );
+
+            if ( $post_type && ! $template->is_custom ) {
+                continue;
+            }
+
+            if ( $post_type &&
+                isset( $template->post_types ) &&
+                ! in_array( $post_type, $template->post_types, true )
+            ) {
+                continue;
+            }
+
+            $is_not_custom   = false === array_search(
+                wp_get_theme()->get_stylesheet() . '//' . $template_file['slug'],
+                array_column( $query_result, 'id' ),
+                true
+            );
+            $fits_slug_query =
+                ! isset( $query['slug__in'] ) || in_array( $template_file['slug'], $query['slug__in'], true );
+            $fits_area_query =
+                ! isset( $query['area'] ) || $template_file['area'] === $query['area'];
+            $should_include  = $is_not_custom && $fits_slug_query && $fits_area_query;
+            if ( $should_include ) {
+                $query_result[] = $template;
+            }
+        }
+    }
+
+    /**
+     * Filters the array of queried block templates array after they've been fetched.
+     *
+     * @since 5.9
+     *
+     * @param WP_Block_Template[] $query_result Array of found block templates.
+     * @param array $query {
+     *     Optional. Arguments to retrieve templates.
+     *
+     *     @type array  $slug__in List of slugs to include.
+     *     @type int    $wp_id Post ID of customized template.
+     * }
+     * @param array $template_type wp_template or wp_template_part.
+     */
+    return apply_filters( 'get_block_templates', $query_result, $query, $template_type );
 }
 
@@ -105 +679 @@
  *
  * @param string $id            Template unique identifier (example: theme_slug//template_slug).
- * @param string $template_type Optional. The template type (post type). Default 'wp_template'.
+ * @param array  $template_type Optional. Template type: `'wp_template'` or '`wp_template_part'`.
+ *                              Default `'wp_template'`.
+ *
  * @return WP_Block_Template|null Template.
  */
 function get_block_template( $id, $template_type = 'wp_template' ) {
+    /**
+     * Filters the block templates array before the query takes place.
+     *
+     * Return a non-null value to bypass the WordPress queries.
+     *
+     * @since 5.9.0
+     *
+     * @param WP_Block_Template|null $block_template Return block template object to short-circuit the default query,
+     *                                               or null to allow WP to run its normal queries.
+     * @param string $id                             Template unique identifier (example: theme_slug//template_slug).
+     * @param array  $template_type                  Template type: `'wp_template'` or '`wp_template_part'`.
+     */
+    $block_template = apply_filters( 'pre_get_block_template', null, $id, $template_type );
+    if ( ! is_null( $block_template ) ) {
+        return $block_template;
+    }
+
     $parts = explode( '//', $id, 2 );
     if ( count( $parts ) < 2 ) {
@@ -132 +725 @@
 
     if ( count( $posts ) > 0 ) {
-        $template = _build_template_result_from_post( $posts[0] );
+        $template = _build_block_template_result_from_post( $posts[0] );
 
         if ( ! is_wp_error( $template ) ) {
@@ -139 +732 @@
     }
 
-    return null;
-}
+    $block_template = get_block_file_template( $id, $template_type );
+
+    /**
+     * Filters the array of queried block templates array after they've been fetched.
+     *
+     * @since 5.9
+     *
+     * @param WP_Block_Template $block_template The found block template.
+     * @param string            $id             Template unique identifier (example: theme_slug//template_slug).
+     * @param array             $template_type  Template type: `'wp_template'` or '`wp_template_part'`.
+     */
+    return apply_filters( 'get_block_template', $block_template, $id, $template_type );
+}
+
+/**
+ * Retrieves a single unified template object using its id.
+ *
+ * @since 5.9.0
+ *
+ * @param string $id            Template unique identifier (example: theme_slug//template_slug).
+ * @param array  $template_type Optional. Template type: `'wp_template'` or '`wp_template_part'`.
+ *                              Default `'wp_template'`.
+ */
+function get_block_file_template( $id, $template_type = 'wp_template' ) {
+    /**
+     * Filters the block templates array before the query takes place.
+     *
+     * Return a non-null value to bypass the WordPress queries.
+     *
+     *
+     * @since 5.9.0
+     *
+     * @param WP_Block_Template|null $block_template Return block template object to short-circuit the default query,
+     *                                               or null to allow WP to run its normal queries.
+     * @param string $id                             Template unique identifier (example: theme_slug//template_slug).
+     * @param array  $template_type                  Template type: `'wp_template'` or '`wp_template_part'`.
+     */
+    $block_template = apply_filters( 'pre_get_block_file_template', null, $id, $template_type );
+    if ( ! is_null( $block_template ) ) {
+        return $block_template;
+    }
+
+    $parts = explode( '//', $id, 2 );
+    if ( count( $parts ) < 2 ) {
+        /** This filter is documented at the end of this function */
+        return apply_filters( 'get_block_file_template', null, $id, $template_type );
+    }
+    list( $theme, $slug ) = $parts;
+
+    if ( wp_get_theme()->get_stylesheet() !== $theme ) {
+        /** This filter is documented at the end of this function */
+        return apply_filters( 'get_block_file_template', null, $id, $template_type );
+    }
+
+    $template_file = _get_block_template_file( $template_type, $slug );
+    if ( null === $template_file ) {
+        /** This filter is documented at the end of this function */
+        return apply_filters( 'get_block_file_template', null, $id, $template_type );
+    }
+
+    $block_template = _build_block_template_result_from_file( $template_file, $template_type );
+
+    /**
+     * Filters the array of queried block templates array after they've been fetched.
+     *
+     * @since 5.9.0
+     *
+     * @param WP_Block_Template $block_template The found block template.
+     * @param string            $id             Template unique identifier (example: theme_slug//template_slug).
+     * @param array             $template_type  Template type: `'wp_template'` or '`wp_template_part'`.
+     */
+    return apply_filters( 'get_block_file_template', $block_template, $id, $template_type );
+}
+
+/**
+ * Print a template-part.
+ *
+ * @since 5.9.0
+ *
+ * @param string $part The template-part to print. Use "header" or "footer".
+ */
+function block_template_part( $part ) {
+    $template_part = get_block_template( get_stylesheet() . '//' . $part, 'wp_template_part' );
+    if ( ! $template_part || empty( $template_part->content ) ) {
+        return;
+    }
+    echo do_blocks( $template_part->content );
+}
+
+/**
+ * Print the header template-part.
+ *
+ * @since 5.9.0
+ */
+function block_header_area() {
+    block_template_part( 'header' );
+}
+
+/**
+ * Print the footer template-part.
+ *
+ * @since 5.9.0
+ */
+function block_footer_area() {
+    block_template_part( 'footer' );
+}