Block Patterns: Automatically load headered files from a theme's /patterns directory

lib/compat/wordpress-6.0/block-patterns.php

@@ -51,3 +51,145 @@ function( $current_screen ) {
 		}
 	}
 );
+
+/**
+ * Register any patterns that the active theme may provide under its
+ * `./patterns/` directory. Each pattern is defined as a PHP file and defines
+ * its metadata using plugin-style headers. The minimum required definition is:
+ *
+ *     /**
+ *      * Title: My Pattern
+ *      * Slug: my-theme/my-pattern
+ *      *
+ *
+ * The output of the PHP source corresponds to the content of the pattern, e.g.:
+ *
+ *     <main><p><?php echo "Hello"; ?></p></main>
+ *
+ * If applicable, this will collect from both parent and child theme.
+ *
+ * Other settable fields include:
+ *
+ *   - Description
+ *   - Viewport Width
+ *   - Categories       (comma-separated values)
+ *   - Keywords         (comma-separated values)
+ *   - Block Types      (comma-separated values)
+ *   - Inserter         (yes/no)
+ *
+ * @since 6.0.0
+ * @access private
+ * @internal
+ */
+function gutenberg_register_theme_block_patterns() {
+	$default_headers = array(
+		'title'         => 'Title',
+		'slug'          => 'Slug',
+		'description'   => 'Description',
+		'viewportWidth' => 'Viewport Width',
+		'categories'    => 'Categories',
+		'keywords'      => 'Keywords',
+		'blockTypes'    => 'Block Types',
+		'inserter'      => 'Inserter',
+	);
+
+	// Register patterns for the active theme. If the theme is a child theme,
+	// let it override any patterns from the parent theme that shares the same
+	// slug.
+	foreach ( wp_get_active_and_valid_themes() as $theme ) {
+		$dirpath = $theme . '/patterns/';
+		if ( file_exists( $dirpath ) ) {
+			$files = glob( $dirpath . '*.php' );
+			if ( $files ) {
+				foreach ( $files as $file ) {
+					$pattern_data = get_file_data( $file, $default_headers );
+
+					if ( empty( $pattern_data['slug'] ) ) {
+						trigger_error(
+							sprintf(
+								/* translators: %s: file name. */
+								__( 'Could not register file "%s" as a block pattern ("Slug" field missing)', 'gutenberg' ),
+								$file
+							)
+						);
+						continue;
+					}
+
+					if ( ! preg_match( '/^[A-z0-9\/_-]+$/', $pattern_data['slug'] ) ) {
+						trigger_error(
+							sprintf(
+								/* translators: %1s: file name; %2s: slug value found. */
+								__( 'Could not register file "%1$s" as a block pattern (invalid slug "%2$s")', 'gutenberg' ),
+								$file,
+								$pattern_data['slug']
+							)
+						);
+					}
+
+					if ( WP_Block_Patterns_Registry::get_instance()->is_registered( $pattern_data['slug'] ) ) {
+						continue;
+					}
+
+					// Title is a required property.
+					if ( ! $pattern_data['title'] ) {
+						trigger_error(
+							sprintf(
+								/* translators: %1s: file name; %2s: slug value found. */
+								__( 'Could not register file "%s" as a block pattern ("Title" field missing)', 'gutenberg' ),
+								$file
+							)
+						);
+						continue;
+					}
+
+					// For properties of type array, parse data as comma-separated.
+					foreach ( array( 'categories', 'keywords', 'blockTypes' ) as $property ) {
+						if ( ! empty( $pattern_data[ $property ] ) ) {
+							$pattern_data[ $property ] = array_filter(
+								preg_split(
+									'/[\s,]+/',
+									(string) $pattern_data[ $property ]
+								)
+							);
+						} else {
+							unset( $pattern_data[ $property ] );
+						}
+					}
+
+					// Parse properties of type int.
+					foreach ( array( 'viewportWidth' ) as $property ) {
+						if ( ! empty( $pattern_data[ $property ] ) ) {
+							$pattern_data[ $property ] = (int) $pattern_data[ $property ];
+						} else {
+							unset( $pattern_data[ $property ] );
+						}
+					}
+
+					// Parse properties of type bool.
+					foreach ( array( 'inserter' ) as $property ) {
+						if ( ! empty( $pattern_data[ $property ] ) ) {
+							$pattern_data[ $property ] = in_array(
+								strtolower( $pattern_data[ $property ] ),
+								array( 'yes', 'true' ),
+								true
+							);
+						} else {
+							unset( $pattern_data[ $property ] );
+						}
+					}
+
+					// The actual pattern content is the output of the file.
+					ob_start();
+					include $file;
+					$pattern_data['content'] = ob_get_clean();
+					if ( ! $pattern_data['content'] ) {
+						continue;
+					}
+
+					register_block_pattern( $pattern_data['slug'], $pattern_data );
+				}
+			}
+		}
+	}
+}
+add_action( 'init', 'gutenberg_register_theme_block_patterns' );