[boost] Re: [request] Sun and IBM users...

From: Daniel James (daniel_at_[hidden])
Date: 2004-09-03 10:49:24

Sorry about all these tests and thanks for your patience. Here's another 
one which uses a slightly different method that I think should will better:

#include <boost/preprocessor/seq/seq.hpp>
#include <boost/preprocessor/detail/split.hpp>
#include <boost/preprocessor/punctuation/comma.hpp>
#include <boost/preprocessor/punctuation/paren.hpp>
#include <boost/preprocessor/tuple/eat.hpp>

#define IS_NULLARY_IMPL(x) \
     BOOST_PP_SPLIT(1, IS_NULLARY_C x BOOST_PP_COMMA() (0)) \
     /**/
#define IS_NULLARY_C() \
     ~, (1) BOOST_PP_RPAREN() BOOST_PP_LPAREN() ~ \
     /**/
#define IS_NULLARY(x) BOOST_PP_SEQ_HEAD(IS_NULLARY_IMPL(x))

IS_NULLARY(())    // 1
IS_NULLARY(()abc) // 1
IS_NULLARY(+)     // 0
IS_NULLARY(xyz)   // 0

#define IS_UNARY(x) IS_NULLARY(IS_UNARY_C x)
#define IS_UNARY_C(a) ()

IS_UNARY((a))    // 1
IS_UNARY((a)abc) // 1
IS_UNARY(+)      // 0
IS_UNARY(xyz)    // 0