code2utf example

'CJK Reserve 1' => 0x2fffd,
      'CJK Reserve 2' => 0x3fffd,
      'Bomofo' => 0x312f,
      'Bomofo Ext' => 0x31b7,
      'Lisu' => 0xa4fd,
      'Yi' => 0xa48f,
    ];

    // Generate characters consisting of starts, midpoints, and ends.     $chars = [];
    foreach ($starts as $key => $value) {
      $chars[] = $this->code2utf($starts[$key]);
      $mid = round(0.5 * ($starts[$key] + $ends[$key]));
      $chars[] = $this->code2utf($mid);
      $chars[] = $this->code2utf($ends[$key]);
    }

    // Merge into a string and tokenize.     $string = implode('', $chars);
    $text_processor = \Drupal::service('search.text_processor');
    assert($text_processor instanceof SearchTextProcessorInterface);
    $out = trim($text_processor->analyze($string));
    $expected = mb_strtolower(implode(' ', $chars));