Recursively iterates over value fields and calls visitor.visit for each one of those. visitor.visit is expected to be a template with the following signature:
Boost Software License Version 1.0. See LICENSE_BOOST.txt for details. Alternatively, this file may be distributed under the terms of the Tango 3-Clause BSD License (see LICENSE_BSD.txt for details).
Copyright (c) 2018 dunnhumby Germany GmbH. All rights reserved.
Generic utility allowing to recursively visit every field in an aggregate and possibly those indirectly reachable from them.
Intended as a common implementation base for various more domain-specific utilities.