使用Boost Preprocessor解析元素序列 [英] Use Boost Preprocessor to Parse sequence of elements

问题描述

我定义了一个宏

#define TYPES (height,int,10)(width,int,20)

如何使用Boost Preprocessor扩展此宏?

How to expand this macro using Boost Preprocessor something like this?

int height = 10;
int width = 20;

我最多只能得到 height，int，10 和 width，int，20 作为字符串，但是不能解析单个元素.

at most i am able to get is height,int,10 and width,int,20 as string but can't parse individual element.

推荐答案

在处理前使用BOOST_PP_VARIADIC_SEQ_TO_SEQ将TYPES转换为((height,int,10))((width,int,20))，以使BOOST_PP_SEQ_FOR_EACH不会窒息:

Using BOOST_PP_VARIADIC_SEQ_TO_SEQ to turn TYPES into ((height,int,10))((width,int,20)) before processing, so that BOOST_PP_SEQ_FOR_EACH doesn't choke on it:

#define MAKE_ONE_VARIABLE(r, data, elem) \
    BOOST_PP_TUPLE_ELEM(1, elem) BOOST_PP_TUPLE_ELEM(0, elem) = BOOST_PP_TUPLE_ELEM(2, elem);

#define MAKE_VARIABLES(seq) \
    BOOST_PP_SEQ_FOR_EACH(MAKE_ONE_VARIABLE, ~, BOOST_PP_VARIADIC_SEQ_TO_SEQ(seq))

用法:

#define TYPES (height,int,10)(width,int,20)

int main() {
    MAKE_VARIABLES(TYPES)
}

已预处理为:

int main() {
    int height = 10; int width = 20;
}

在Coliru上实时观看

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