从源中提取预处理器符号 [英] Extracting preprocessor symbols from source

问题描述

我正在寻找一种提取代码中使用的所有预处理器符号的方法.
例如，如果我的代码如下:

I'm looking for a way to extract all preprocessor symbols used in my code.
As an example, if my code looks like this:

#ifdef FOO
#endif

#if ( BAR == 1 && \
      defined (Z) )
#endif

我想获取列表 [FOO，BAR，Z] 作为输出.

I'd like to get the list [FOO,BAR,Z] as the output.

我发现一些帖子建议 gcc -E -dM ，但这显示了预处理器将应用于代码的所有符号.
相反，我想要的是在代码中实际使用的所有符号的列表.

I found some posts suggesting gcc -E -dM, but this displays all symbols that the preprocessor would apply to the code.
What I want, in contrast, is a list of all symbols actually used in the code.

有什么建议吗?

推荐答案

这很简单.您只需按照一致的预处理程序的方式完全解析源代码，并使用正确的C或C ++版本支持即可.好吧，我在开玩笑，如果您仅支持更高版本，则您的代码可能会在较旧版本上产生正确的结果-甚至应该对此进行完全控制.

That's quite simple. You have just to parse the source code exactly the way a conformant pre-processor would, and with the correct C or C++ version support. Ok, I'm joking, if you support only the later version, your code is likely to produce correct results on older versions - but even this should be thoroughly controlled.

现在更加认真.正如您可以要求预处理器为您提供所有已定义符号的列表一样，您可以简单地对源进行 tokenize ，并从该列表中识别出所有紧随初始#define或#之后的令牌undef.这部分应该可以在lex + yacc上实现.

More seriously now. As you can ask the pre-processor to give you the list of all defined symbols, you can simply tokenize the source, and identify all tokens from that list that are not immediately following an initial #define or #undef. This part should be reasonably feasable with lex+yacc.

我能想到的唯一选择是使用真正的编译器的代码(Clang应该比gcc更容易，但不确定)丢弃所有代码生成并始终存储每个宏用法.

The only alternative I can imagine would be to use the code of a real compiler (Clang should be easier than gcc but unsure) discard all code generation and consistently store every macro usage.

TL/DR:但是，如果您接受的话，那将是一项艰巨的工作:如果您不能这样做，请远离...

TL/DR: however you take it, it will be a hard work: if you can do without, keep away from that...

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