C++ boost::spirit parse and call C++ function

The attached compiles and runs. Need code modified such that I parse_phrase will parse the expression and call corresponding member function. For example given: [login to view URL], (see source code) I'd like to invoke the member function processDataTime after qi parsed the expression dateTimeVec. Of course an alternative is to potentially leave the current parse_phrase approach and post process the Metadata struct invoking the appropriate member functions. This we can discuss. Library used boost 1.56 albeit 1.57 should suffice