class JsonEncoder

class JsonEncoder extends BaseJsonEncoder implements EncoderInterface, DecoderInterface {
  
  /**
   * The formats that this Encoder supports.
   *
   * @var array
   */
  protected static $format = [
    'json',
    'ajax',
  ];
  
  /**
   * {@inheritdoc}
   */
  public function __construct(JsonEncode $encodingImpl = NULL, JsonDecode $decodingImpl = NULL) {
    $this->encodingImpl = $encodingImpl ?: $this->getJsonEncode();
    $this->decodingImpl = $decodingImpl ?: $this->getJsonDecode();
  }
  
  /**
   * Instantiates a JsonEncode instance.
   *
   * @internal this exists to bridge Symfony 3 to Symfony 4, and can be removed
   *   once Drupal requires Symfony 4.2 or higher.
   */
  private function getJsonEncode() {
    // Encode <, >, ', &, and " for RFC4627-compliant JSON, which may also be
    // embedded into HTML.
    // @see \Symfony\Component\HttpFoundation\JsonResponse
    $json_encoding_options = JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT;
    $reflection = new \ReflectionClass(JsonEncode::class);
    if (array_key_exists('OPTIONS', $reflection->getConstants())) {
      return new JsonEncode([
        JsonEncode::OPTIONS => $json_encoding_options,
      ]);
    }
    return new JsonEncode($json_encoding_options);
  }
  
  /**
   * Instantiates a JsonDecode instance.
   *
   * @internal this exists to bridge Symfony 3 to Symfony 4, and can be removed
   *   once Drupal requires Symfony 4.2 or higher.
   */
  private function getJsonDecode() {
    $reflection = new \ReflectionClass(JsonDecode::class);
    if (array_key_exists('ASSOCIATIVE', $reflection->getConstants())) {
      return new JsonDecode([
        JsonDecode::ASSOCIATIVE => TRUE,
      ]);
    }
    return new JsonDecode(TRUE);
  }
  
  /**
   * {@inheritdoc}
   */
  public function supportsEncoding($format) {
    return in_array($format, static::$format);
  }
  
  /**
   * {@inheritdoc}
   */
  public function supportsDecoding($format) {
    return in_array($format, static::$format);
  }

}