Re: Fwd: dependency tee from c parser entities downto token

[Konrad Eisele <konrad@xxxxxxxxxxx>]

Christopher Li wrote:
> On Sat, May 5, 2012 at 4:38 PM, Konrad Eisele<eiselekd@xxxxxxxxx>  wrote:
> > I appended a diff for review. Is this kind of interface ok?
> > This is kind of not a patch to apply, rather I want to avoid to put
> > effort in it and you telling me later I am too intrusive...:). So
> > can you give a ok or comment...
> >
> > Interface so far:
> > struct preprocess_hook {
> >         def      : called when #define is processed
>
> Why do you need #define hooks? The macro symbol
> should have pos and macro body already.

I need to hook to insert a TOKEN_M_EMPTY into the substitution body
if the define is an empty define. The "post" hook is then used to
remove all TOKEN_M_EMPTY again after the preprocessing (or rather
to save it internally).

> >         args_beg : called before argument expasnion
> >         args_end : called after argument expasnion
> >         body_beg : called before body expansion
> >         body_end : called after body expansion
>
> I am wondering why is do you need 4 call backs for macro
> expand instead of just one like the patch I post previously.
> That macro expand give you the name of the macro need to
> be expand and the replacement list.  My guess is that you
> want the end position of the macro before expand. That
> can be add to the macro expand hook. Will that be sufficient?

I want to trace the complete macro substitution. Using a before-after
hook for both body and arg I can reconstruct what is done in the
expand (Not just dependencies but the whole of expand).


> >         post     : called after preprocess
>
> I don't think the post call back is needed. You can call
> the preprocessor directly. It will return when it complete.
> Then you can do your post work. You can invoke the parser
> separately.  The sparse wrapper function does it all in
> one function but that did not stop you it step by step
> if you wants to.

See above. I need the post to filter out the helper TOKEN_M_EMPTY.

> > All of there I found are needed. There might be more to be added...
> >
> > I also introduce a tokentype TOKEN_M_EMPTY so that I can track
> > empty expansion. To filter these out again I add the post hook.
>
> What purpose does the token_m_empty if you filter those token later?
> Rember where in the stream there is an invisible macro?

See above. I use it as a placeholder. The "post" hook saves the information
then and removes the token again.




> Chris
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