Boost C++ Libraries

VMD has the ability to retrieve the type of any data which it can parse, which means any VMD sequence. The generic macro to do this is called BOOST_VMD_GET_TYPE and it takes a single required variadic parameter, which is a VMD sequence. Since a VMD sequence is any data which VMD can parse the BOOST_VMD_GET_TYPE macro works with any VMD data.

It returns one of the types previously discussed when introducing v-types as an identifier subset. As explained previously in that topic a v-type is fully recognized by VMD macros and can be part of a sequence and passed as VMD data just like all the other data types VMD recognizes.

When BOOST_VMD_GET_TYPE returns the type of data it returns by default the most specific type that the data can be. This means that non-empty lists and arrays are returned as such, not as tuples, and numbers and types and empty lists are returned as such, not as identifiers.

#include <boost/vmd/get_type.hpp>

#define BOOST_VMD_REGISTER_ANID (ANID)
#define SEQUENCE_EMPTY
#define SEQUENCE_MULTI (1,2,3) 88
#define SEQUENCE1 (3,(1,2,3))
#define SEQUENCE2 ANID
#define SEQUENCE3 (1,(2,(3,BOOST_PP_NIL)))
#define SEQUENCE4 1
#define SEQUENCE5 (1)(2)(3)
#define SEQUENCE6 (1,2,3)
#define SEQUENCE7 BOOST_VMD_TYPE_NUMBER

BOOST_VMD_GET_TYPE(SEQUENCE_EMPTY) will return BOOST_VMD_TYPE_EMPTY
BOOST_VMD_GET_TYPE(SEQUENCE_MULTI) will return BOOST_VMD_TYPE_SEQUENCE
BOOST_VMD_GET_TYPE(SEQUENCE1) will return BOOST_VMD_TYPE_ARRAY
BOOST_VMD_GET_TYPE(SEQUENCE2) will return BOOST_VMD_TYPE_IDENTIFIER
BOOST_VMD_GET_TYPE(SEQUENCE3) will return BOOST_VMD_TYPE_LIST
BOOST_VMD_GET_TYPE(SEQUENCE4) will return BOOST_VMD_TYPE_NUMBER
BOOST_VMD_GET_TYPE(SEQUENCE5) will return BOOST_VMD_TYPE_SEQ
BOOST_VMD_GET_TYPE(SEQUENCE6) will return BOOST_VMD_TYPE_TUPLE
BOOST_VMD_GET_TYPE(SEQUENCE7) will return BOOST_VMD_TYPE_TYPE

Usage

You can use the general header file:

#include <boost/vmd/vmd.hpp>

or you can use the individual header file:

#include <boost/vmd/get_type.hpp>

for the BOOST_VMD_GET_TYPE macro.