How to zip multiple Boost Preprocessor sequences?

问题

Given multiple Boost Preprocessor sequences:

#define S1 (a)(b)(c)
#define S2 (1)(2)(3)
#define S3 (x1)(x2)(x3)

How do I zip them using the preprocessor so the end result would be ((a)(1)(x1))((b)(2)(x2))((c)(3)(x3))?

Notes

• I came up with my own answer, but I'm open to accepting better solutions than provided by my answer below in reasonable time.
• Please refrain from removing the c tag since this Boost.Preprocessor works well with C++ as well as C, and my question targets both languages.

回答1:

You can define a SEQ_ZIP macro for this purpose as follows:

#include <boost/preprocessor/control/expr_if.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/preprocessor/seq/elem.hpp>
#include <boost/preprocessor/seq/for_each.hpp>
#include <boost/preprocessor/seq/size.hpp>

#define SEQ_ZIP_NTH_(_,d,e) (BOOST_PP_SEQ_ELEM(d, e))
#define SEQ_ZIP_NTHS_(_,i,ss) (BOOST_PP_SEQ_FOR_EACH(SEQ_ZIP_NTH_,i,ss))
#define SEQ_ZIP_2(ne,ss) BOOST_PP_REPEAT(ne, SEQ_ZIP_NTHS_, ss)
#define SEQ_ZIP_(ne,ss) BOOST_PP_EXPR_IF(ne, SEQ_ZIP_2(ne, ss))
#define SEQ_ZIP(ss) SEQ_ZIP_(BOOST_PP_SEQ_SIZE(BOOST_PP_SEQ_ELEM(0,ss)), ss)

And use it to zip your sequences like this:

#define S1 (a)(b)(c)
#define S2 (1)(2)(3)
#define S3 (x1)(x2)(x3)
SEQ_ZIP((S1)(S2)(S3))

来源：https://stackoverflow.com/questions/41987222/how-to-zip-multiple-boost-preprocessor-sequences