1<?php
  2/**
  3 * Server-side rendering of the `core/button` block.
  4 *
  5 * @package WordPress
  6 */
  7
  8/**
  9 * Renders the `core/button` block on the server,
 10 *
 11 * @since 6.6.0
 12 *
 13 * @param array  $attributes The block attributes.
 14 * @param string $content    The block content.
 15 *
 16 * @return string The block content.
 17 */
 18function render_block_core_button( $attributes, $content ) {
 19	$p = new WP_HTML_Tag_Processor( $content );
 20
 21	/*
 22	 * The button block can render an `<a>` or `<button>` and also has a
 23	 * `<div>` wrapper. Find the a or button tag.
 24	 */
 25	$tag = null;
 26	while ( $p->next_tag() ) {
 27		$tag = $p->get_tag();
 28		if ( 'A' === $tag || 'BUTTON' === $tag ) {
 29			break;
 30		}
 31	}
 32
 33	/*
 34	 * If this happens, the likelihood is there's no block content,
 35	 * or the block has been modified by a plugin.
 36	 */
 37	if ( null === $tag ) {
 38		return $content;
 39	}
 40
 41	// If the next token is the closing tag, the button is empty.
 42	$is_empty = true;
 43	while ( $p->next_token() && $tag !== $p->get_token_name() && $is_empty ) {
 44		if ( '#comment' !== $p->get_token_type() ) {
 45			/**
 46			 * Anything else implies this is not empty.
 47			 * This might include any text content (including a space),
 48			 * inline images or other HTML.
 49			 */
 50			$is_empty = false;
 51		}
 52	}
 53
 54	/*
 55	 * When there's no text, render nothing for the block.
 56	 * See https://github.com/WordPress/gutenberg/issues/17221 for the
 57	 * reasoning behind this.
 58	 */
 59	if ( $is_empty ) {
 60		return '';
 61	}
 62
 63	return $content;
 64}
 65
 66/**
 67 * Registers the `core/button` block on server.
 68 *
 69 * @since 6.6.0
 70 */
 71function register_block_core_button() {
 72	register_block_type_from_metadata(
 73		__DIR__ . '/button',
 74		array(
 75			'render_callback' => 'render_block_core_button',
 76		)
 77	);
 78}
 79add_action( 'init', 'register_block_core_button' );
 80