class NormalizerBase

abstract class NormalizerBase extends SerializationNormalizerBase {
    
    /**
     * {@inheritdoc}
     */
    protected $format = 'api_json';
    
    /**
     * Rasterizes a value recursively.
     *
     * This is mainly for configuration entities where a field can be a tree of
     * values to rasterize.
     *
     * @param mixed $value
     *   Either a scalar, an array or a rasterizable object.
     *
     * @return mixed
     *   The rasterized value.
     */
    protected static function rasterizeValueRecursive($value) {
        if (!$value || is_scalar($value)) {
            return $value;
        }
        if (is_array($value)) {
            $output = [];
            foreach ($value as $key => $item) {
                $output[$key] = static::rasterizeValueRecursive($item);
            }
            return $output;
        }
        if ($value instanceof CacheableNormalization) {
            return $value->getNormalization();
        }
        // If the object can be turned into a string it's better than nothing.
        if (method_exists($value, '__toString')) {
            return $value->__toString();
        }
        // We give up, since we do not know how to rasterize this.
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function checkFormat($format = NULL) {
        // The parent implementation allows format-specific normalizers to be used
        // for normalization without a format. The JSON:API module wants to be
        // cautious. Hence it only allows its normalizers to be used for the
        // JSON:API format, to avoid JSON:API-specific normalizations showing up in
        // the REST API.
        return $format === $this->format;
    }

}