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<?php/**
 * Appending the wp-block-heading to before rendering the stored `core/heading` block contents.
 *
 * @package WordPress
 */
 
 /**
 * Adds a wp-block-heading class to the heading block content.
 *
 * For example, the following block content:
 *  <h2 class="align-left">Hello World</h2>
 *
 * Would be transformed to:
 *  <h2 class="align-left wp-block-heading">Hello World</h2>
 *
 * @since 6.2.0
 *
 * @param array  $attributes Attributes of the block being rendered.
 * @param string $content Content of the block being rendered.
 *
 * @return string The content of the block being rendered.
 */
 function block_core_heading_render( $attributes, $content ) {
 if ( ! $content ) {
 return $content;
 }
 
 $p = new WP_HTML_Tag_Processor( $content );
 
 $header_tags = array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' );
 while ( $p->next_tag() ) {
 if ( in_array( $p->get_tag(), $header_tags, true ) ) {
 $p->add_class( 'wp-block-heading' );
 break;
 }
 }
 
 return $p->get_updated_html();
 }
 
 /**
 * Registers the `core/heading` block on server.
 *
 * @since 6.2.0
 */
 function register_block_core_heading() {
 register_block_type_from_metadata(
 __DIR__ . '/heading',
 array(
 'render_callback' => 'block_core_heading_render',
 )
 );
 }
 
 add_action( 'init', 'register_block_core_heading' );
 
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