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