Base::convertValueSingle

static function convertValueSingle(FieldType $fieldType, $value, $toTypeClass)
{
	$value = static::toSingleValue($fieldType, $value);
	/** @var Base $toTypeClass */
	$result = static::convertTo($fieldType, $value, $toTypeClass);
	if ($result === null)
		$result = $toTypeClass::convertFrom($fieldType, $value, get_called_class());

	if ($result !== null)
		$fieldType->setTypeClass($toTypeClass);

	return $result !== null ? $result : $value;
}