[WIP] Enqueue only required frontend styles - V1

lib/blocks.php

@@ -115,6 +115,27 @@ function gutenberg_render_block( $block ) {
 	return '';
 }
 
+/**
+ * Prefixes the core namespace ('core/') to the block type name if the namespace isn't found in the block type name
+ *
+ * @since 2.7.0
+ *
+ * @param  string $block_type Name of the block type.
+ * @return string             Name of the block type, prefixed by the core namespace if needed.
+ */
+function gutenberg_normalize_block_type( $block_type ) {
+	$block_type = trim( $block_type );
+
+	$index_of_slash = strpos( $block_type, '/' );
+
+	// If namespace isn't found in the block type name, prefix it with 'core/'.
+	if ( false === $index_of_slash ) {
+		return 'core/' . $block_type;
+	}
+
+	return $block_type;
+}
+
 /**
  * Parses dynamic blocks out of `post_content` and re-renders them.
  *
@@ -123,7 +144,8 @@ function gutenberg_render_block( $block ) {
  * @param  string $content Post content.
  * @return string          Updated post content.
  */
-function do_blocks( $content ) {
+function gutenberg_render_dynamic_blocks( $content ) {
+
 	$rendered_content = '';
 
 	$dynamic_block_names   = get_dynamic_block_names();
@@ -154,15 +176,14 @@ function do_blocks( $content ) {
 		}
 
 		// Since content is a working copy since the last match, append to
-		// rendered content up to the matched offset...
-		$rendered_content .= substr( $content, 0, $offset );
+		// rendered content up to the matched offset (including the opening tag)...
+		$rendered_content .= substr( $content, 0, $offset + strlen( $opening_tag ) );
 
 		// ...then update the working copy of content.
 		$content = substr( $content, $offset + strlen( $opening_tag ) );
 
 		// Make implicit core namespace explicit.
-		$is_implicit_core_namespace = ( false === strpos( $block_name, '/' ) );
-		$normalized_block_name      = $is_implicit_core_namespace ? 'core/' . $block_name : $block_name;
+		$normalized_block_name = gutenberg_normalize_block_type( $block_name );
 
 		// Find registered block type. We can assume it exists since we use the
 		// `get_dynamic_block_names` function as a source for pattern matching.
@@ -188,20 +209,97 @@ function do_blocks( $content ) {
 				break;
 			}
 
-			// Update content to omit text up to and including closing tag.
+			// Update content to omit text up to the closing tag.
 			$end_tag    = $block_match_end[0][0];
 			$end_offset = $block_match_end[0][1];
 
-			$content = substr( $content, $end_offset + strlen( $end_tag ) );
+			$content = substr( $content, $end_offset );
 		}
 	}
 
 	// Append remaining unmatched content.
 	$rendered_content .= $content;
 
-	// Strip remaining block comment demarcations.
-	$rendered_content = preg_replace( '/<!--\s+\/?wp:.*?-->\r?\n?/m', '', $rendered_content );
-
 	return $rendered_content;
 }
-add_filter( 'the_content', 'do_blocks', 9 ); // BEFORE do_shortcode().
+
+/**
+ * For a single post / page, this function parses `block types` while stripping
+ * `block comments` from the post's HTML and calls WP_Parsed_Block_Types_Registry
+ * to save those parsed block types. It registers gutenberg_process_block_comment()
+ * as a callback function for preg_replace_callback(). For each block comment
+ * (matched by the Regex) in the post's HTML, gutenberg_process_block_comment()
+ * will get called.
+ *
+ * For pages containing multiple posts like category / archive / home page, this only strips
+ * block comments (doesn't save the parsed block types in WP_Parsed_Block_Types_Registry).
+ * We don't need to save `parsed block types` for such pages since intelligent enqueuing of
+ * front-end styles (only enqueue styles for `block types` present in the post/page)
+ * only needs to happen for single posts / pages as of now.
+ *
+ * @since 2.7.0
+ *
+ * @param  string $content Post content.
+ * @return string          Updated post content (without block comments)
+ */
+function gutenberg_process_block_comments( $content ) {
+
+	// Checks if a single page/post is requested.
+	$is_post_or_page = is_singular( array( 'post', 'page' ) );
+
+	/*
+	 * If a single page/post is requested, we need to parse and save `parsed block types` while stripping block comments.
+	 * Otherwise, for category / archive / home page etc, we can simply strip block comments and return the HTML.
+	 */
+
+	if ( $is_post_or_page ) {
+		$content = preg_replace_callback( '/<!--\s+\/?wp:.*?-->\r?\n?/m', 'gutenberg_process_block_comment', $content );
+	} else {
+		$content = preg_replace( '/<!--\s+\/?wp:.*?-->\r?\n?/m', '', $content );
+	}
+
+	return $content;
+}
+
+/**
+ * Registered as a callback function to preg_replace_callback() and is called once for each
+ * block comment parsed from the post's HTML. It returns an empty string for each instantiation
+ * so that the post's HTML gets stripped of block comments.
+ *
+ * Also, it uses WP_Parsed_Block_Types_Registry to store block types parsed from the block comments.
+ * Those can be later used if needed.
+ *
+ * @since 2.7.0
+ *
+ * @param  string $matches An array filled with the results of search.
+ *                         $matches[0] will contain the text that matched the full pattern,
+ *                         $matches[1] will have the text that matched the first captured parenthesized subpattern,
+ *                         and so on.
+ * @return string          Returns an empty string to preg_replace_callback() for each of the block comments
+ */
+function gutenberg_process_block_comment( $matches ) {
+
+	$block_comment = $matches[0];
+
+	// Only process the block comment if it's not a closing tag for a block. If it's a closing tag, we can just return.
+	if ( preg_match( '/\/wp:/m', $block_comment ) !== 1 ) {
+
+		preg_match( '/wp:(.*?)\s+/m', $block_comment, $match );
+
+		$block_type_name = $match[1];
+		$block_type_name = gutenberg_normalize_block_type( $block_type_name );
+
+		WP_Parsed_Block_Types_Registry::get_instance()->add( $block_type_name );
+	}
+
+	return '';
+}
+
+add_filter( 'the_content', 'gutenberg_render_dynamic_blocks', 9 ); // BEFORE do_shortcode().
+
+/*
+ * This needs to run as late as possible so as to let plugins apply filters to content first.
+ * Have subtracted 1 from the priority since `enqueue_required_frontend_block_styles()`
+ * needs to run after this. Have given that filter PHP_INT_MAX priority.
+ */
+add_filter( 'the_content', 'gutenberg_process_block_comments', PHP_INT_MAX - 1 );

lib/class-wp-block-type-registry.php

@@ -56,22 +56,13 @@ public function register( $name, $args = array() ) {
 			$name       = $block_type->name;
 		}
 
-		if ( ! is_string( $name ) ) {
-			$message = __( 'Block type names must be strings.', 'gutenberg' );
-			_doing_it_wrong( __METHOD__, $message, '0.1.0' );
-			return false;
-		}
+		$block_type_validator = new WP_Block_Type_Validator();
+		$is_block_type_valid  = $block_type_validator->validate( $name );
 
-		if ( preg_match( '/[A-Z]+/', $name ) ) {
-			$message = __( 'Block type names must not contain uppercase characters.', 'gutenberg' );
-			_doing_it_wrong( __METHOD__, $message, '1.5.0' );
-			return false;
-		}
+		if ( ! $is_block_type_valid ) {
+			$error = $block_type_validator->get_last_error();
+			_doing_it_wrong( __METHOD__, $error['error_text'], $error['added_from_version'] );
 
-		$name_matcher = '/^[a-z0-9-]+\/[a-z0-9-]+$/';
-		if ( ! preg_match( $name_matcher, $name ) ) {
-			$message = __( 'Block type names must contain a namespace prefix. Example: my-plugin/my-custom-block-type', 'gutenberg' );
-			_doing_it_wrong( __METHOD__, $message, '0.1.0' );
 			return false;
 		}
 

lib/class-wp-block-type-validator.php

@@ -0,0 +1,124 @@
+<?php
+/**
+ * Blocks API: WP_Block_Type_Validator class
+ *
+ * @package gutenberg
+ * @since 2.7.0
+ */
+
+/**
+ * Core class used for validation of block type names
+ *
+ * @since 2.7.0
+ */
+class WP_Block_Type_Validator {
+
+	/**
+	 * A container (array) for storing errors encountered by the validator.
+	 *
+	 * Each error is itself an array with `error_text` and `added_from_version` keys.
+	 *
+	 * @var array $errors Array for storing errors encountered by the Validator
+	 */
+	private $errors = array();
+
+	/**
+	 * Validates a block type name
+	 *
+	 * @since 2.7.0
+	 * @access public
+	 *
+	 * @param string|WP_Block_Type $name Block type name including namespace, or alternatively a
+	 *                                   complete WP_Block_Type instance.
+	 * @return true|false                True on success, or false on failure.
+	 */
+	public function validate( $name ) {
+
+		if ( $name instanceof WP_Block_Type ) {
+			$name = $block_type->name;
+		}
+
+		if ( ! is_string( $name ) ) {
+			$message = __( 'Block type names must be strings.', 'gutenberg' );
+			$this->set_error( $message, '0.1.0' );
+
+			return false;
+		}
+
+		if ( preg_match( '/[A-Z]+/', $name ) ) {
+			$message = __( 'Block type names must not contain uppercase characters.', 'gutenberg' );
+			$this->set_error( $message, '1.5.0' );
+
+			return false;
+		}
+
+		$name_matcher = '/^[a-z0-9-]+\/[a-z0-9-]+$/';
+		if ( ! preg_match( $name_matcher, $name ) ) {
+			$message = __( 'Block type names must contain a namespace prefix. Example: my-plugin/my-custom-block-type', 'gutenberg' );
+			$this->set_error( $message, '0.1.0' );
+
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Set an error in the validator
+	 *
+	 * This function can be used to set an error in the Validator
+	 * Please note that this function adds the error to the existing $this->errors array
+	 * It does not flush the existing errors object
+	 *
+	 * @param string $error_text         A string denoting the error message.
+	 * @param string $added_from_version A string denoting the version of WordPress where the error message was added.
+	 */
+	public function set_error( $error_text, $added_from_version = '' ) {
+		$this->errors[] = array(
+			'error_text'         => $error_text,
+			'added_from_version' => $added_from_version,
+		);
+	}
+
+	/**
+	 * Checks if the Validator encountered any errors in validation
+	 *
+	 * This function checks $this->errors array and returns true if there are any errors in it.
+	 * If yes, it returns true. If no, it returns false.
+	 *
+	 * @return bool True/False
+	 */
+	public function has_errors() {
+		return ! empty( $this->errors ) ? true : false;
+	}
+
+	/**
+	 * Get errors stored in the Validator
+	 *
+	 * This function returns the $this->errors array
+	 *
+	 * @return array An array is returned containing the errors stored in the Validator.
+	 *               The returned array is an array of errors.
+	 *               Each individual error is an array with `error_text` and `added_from_version` keys.
+	 *               If there are no errors stored, an empty array is returned
+	 */
+	public function get_errors() {
+		return $this->errors;
+	}
+
+	/**
+	 * Get the last error encountered by the Validator
+	 *
+	 * @return array|bool An array containing `error_text` and `added_from_version` keys
+	 *                    If there are no errors stored in the validator, FALSE (boolean) is returned
+	 */
+	public function get_last_error() {
+		$error_count = count( $this->errors );
+
+		if ( 0 === $error_count ) {
+			return false;
+		} else {
+			return $this->errors[ $error_count - 1 ];
+		}
+	}
+}