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   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   */
  18  function 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   */
  71  function 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  }
  79  add_action( 'init', 'register_block_core_button' );