Blocks/refactor twentytwentyone block processor

phpcs.xml.dist

@@ -229,7 +229,7 @@
 	#############################################################################
 	SELECTIVE EXCLUSIONS
 	Exclude specific files for specific sniffs and/or exclude sub-groups in sniffs.
-	
+
 	These exclusions are listed ordered by alphabetic sniff name.
 	#############################################################################
 	-->
@@ -266,8 +266,9 @@
 
 		<!-- Goto is an effective way to handle errors in decoders which expect valid bytes
 		     without impacting the fast path while avoiding bloating the code with redundant
-		     and risky handling code. Exclude forbidding goto in UTF-8 fallback code. -->
+		     and risky handling code. Exclude forbidding goto in parser code. -->
 		<exclude-pattern>/wp-includes/compat-utf8\.php</exclude-pattern>
+		<exclude-pattern>/wp-includes/class-wp-block-processor\.php</exclude-pattern>
 	</rule>
 
 	<!-- Exclude sample config from modernization to prevent breaking CI workflows based on WP-CLI scaffold.

src/wp-content/themes/twentytwentyone/inc/template-functions.php

@@ -361,46 +361,32 @@ function twenty_twenty_one_get_non_latin_css( $type = 'front-end' ) {
  * @return bool Returns true if a block was located & printed, otherwise false.
  */
 function twenty_twenty_one_print_first_instance_of_block( $block_name, $content = null, $instances = 1 ) {
-	$instances_count = 0;
 	$blocks_content  = '';
 
 	if ( ! $content ) {
 		$content = get_the_content();
 	}
 
-	// Parse blocks in the content.
-	$blocks = parse_blocks( $content );
+	$processor      = new WP_Block_Processor( $content );
+	$instance_count = 0;
 
-	// Loop blocks.
-	foreach ( $blocks as $block ) {
+	if ( str_ends_with( $block_name, '*' ) ) {
+		// Scan for blocks whose block type matches the prefix.
+		$prefix = rtrim( $block_name, '*' );
 
-		// Confidence check.
-		if ( ! isset( $block['blockName'] ) ) {
-			continue;
-		}
-
-		// Check if this the block matches the $block_name.
-		$is_matching_block = false;
-
-		// If the block ends with *, try to match the first portion.
-		if ( '*' === $block_name[-1] ) {
-			$is_matching_block = 0 === strpos( $block['blockName'], rtrim( $block_name, '*' ) );
-		} else {
-			$is_matching_block = $block_name === $block['blockName'];
-		}
-
-		if ( $is_matching_block ) {
-			// Increment count.
-			++$instances_count;
-
-			// Add the block HTML.
-			$blocks_content .= render_block( $block );
-
-			// Break the loop if the $instances count was reached.
-			if ( $instances_count >= $instances ) {
-				break;
+		while ( $instance_count < $instances && $processor->next_block( '*' ) ) {
+			$matched_block_type = $processor->get_printable_block_type();
+			if ( str_starts_with( $matched_block_type, $prefix ) ) {
+				$blocks_content .= render_block( $processor->extract_block() );
+				++$instance_count;
 			}
 		}
+	} else {
+		// Scan for blocks of the exact block type.
+		while ( $instance_count < $instances && $processor->next_block( $block_name ) ) {
+			$blocks_content .= render_block( $processor->extract_block() );
+			++$instance_count;
+		}
 	}
 
 	if ( $blocks_content ) {

src/wp-includes/blocks.php

@@ -2376,6 +2376,17 @@ function render_block( $parsed_block ) {
 /**
  * Parses blocks out of a content string.
  *
+ * Given an HTML document, this function fully-parses block content, producing
+ * a tree of blocks and their contents, as well as top-level non-block content,
+ * which will appear as a block with no `blockName`.
+ *
+ * This function can be memory heavy for certain documents, particularly those
+ * with deeply-nested blocks or blocks with extensive attribute values. Further,
+ * this function must parse an entire document in one atomic operation.
+ *
+ * If the entire parsed document is not necessary, consider using {@see WP_Block_Processor}
+ * instead, as it provides a streaming and low-overhead interface for finding blocks.
+ *
  * @since 5.0.0
  *
  * @param string $content Post content.