[cfe-dev] Preprocessor/Parser interaction

[Sean Silva]

Here is a simple PPCallbacks example:
https://github.com/chisophugis/clang_plugin_example

Let me know if you have any problems building.

--Sean Silva

On Thu, Feb 23, 2012 at 3:59 AM, Aditya Kumar <hiraditya at msn.com> wrote:

>
>
> Thank you for the link.  Today I tried to regenerate the
> PrintFunctionNames plugin. It works fine. But the same approach didn't work
> for PPCallbacks as you rightly said.
> So if you can post a basic example of PPCallbacks, that would be very
> helpful for me.
>
> ------------------------------
> Date: Wed, 22 Feb 2012 10:53:47 -0500
> Subject: Re: [cfe-dev] Preprocessor/Parser interaction
> From: silvas at purdue.edu
> To: hiraditya at msn.com
>
>
> There's a huge amount of boilerplate needed to do what you want, and it
> will still be missing things like #include paths which will render your
> program unusable for real code.
>
> The dependency graph of objects that need to be created in order to get a
> Preprocessor is gigantic. I manually tracked it here as I was exploring the
> APIs myself: http://web.ics.purdue.edu/~silvas/deps.svg .
> CompilerInstance reduces the amount of boilerplate needed, but there are
> still crucial things missing for it to be "useful" (see:
> https://github.com/loarabia/Clang-tutorial/blob/master/CItutorial3.cpp and
> try including stdio.h in test.c).
>
> A couple weeks ago I went down this path that you are trying to go down,
> and I can tell you that you are not going to achieve what you want by doing
> it like this (e.g., as a standalone program using the Clang libs). There
> are just too many little things that need to be configured in specific ways
> for the compiler to work "as usual, except also run my
> (PPCallbacks|ASTConsumer|...)". My recommendation is to write a Clang
> plugin, so that you can forget about all those things. There is an example
> plugin called PrintFunctionNames in examples/PrintFunctionNames that you
> can look at (although TBH I found it extremely unhelpful for some reason).
> If you want, I can post on github a minimal "hello world" example for how
> to run a PPCallbacks.
>
> --Sean Silva
>
> On Tue, Feb 21, 2012 at 5:35 PM, Aditya Kumar <hiraditya at msn.com> wrote:
>
>  I want to use a PPCallback function (MacroExpands) to track all the
> locations where
> a macro has been invoked in the program.
> In the main function, there are a few things that I want to implement,
> details are
> given as comment inside the main function.
>
> Till now what I have done is the following:
>
> namespace clang {
>
> class MyASTAction : public FrontendAction
> {
>   public:
>     ASTConsumer *CreateASTConsumer(CompilerInstance &CI,
>                   llvm::StringRef InFile)
>     {    return 0;   }
>     void ExecuteAction() { }
>
>     bool usesPreprocessorOnly() const
>     { return false; }
> };
>
> class TrackMacro : public PPCallbacks
> {
>   public:
>   void MacroExpands(const Token &MacroNameTok, const MacroInfo* MI,
>                     SourceRange Range)
>   {
>     std::cout<<"Macro expands to"<<MacroNameTok.getRawIdentifierData();
>   }
>   ~TrackMacro(){}
> };
>
> }
>
> using namespace clang;
> int main(int argc, const char** argv)
> {
>   MyASTAction action;
>   CompilerInstance Clang;
>
> /*****************************************
>
> How to create an instance of the preprocessor class, it seems like
> it takes too many(9) arguments which I was not able to figure out.
> Or is there a way to just create a default preprocessor and add my
> own call back function to it. And then pass the preprocessor object
> to the Parser and invoke the parser just by supplying a filename.
>
> *****************************************/
>   TrackMacro track_macro;
>   PP.addPPCallbacks(&track_macro);
>
>   Clang.setPreprocessor(PP);
>
>    MyASTAction* Act = new MyASTAction();
>    Clang.ExecuteAction(*Act);
>
> return 0;
> }
>
>
>
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>
>
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