[cfe-dev] Creating single AST for multiple files

[Deepak Rajendrakumaran]

James,

Thank you for answering my query.

I might have misunderstood the issues. We have been using 'Rose', which is
another source to source compiler. Rose generates a single AST. I expected
something similar which is why I was looking for a way to generate a single
AST. But having gone through some some documentation, it seems like it is
indeed possible to implement this using multiple ASTs. But my problem is I
will need to revisit each AST multiple times and make incremental changes
on source files. Is 'clang-apply-replacements' a solution to this?


I am also confused as to if I should be using LibClang or LibTooling
keeping in mind I'll need to make significant changes to my source code. Is
there any functionality constraint on LibClang/LibTooling which I can use
to make up my mind??

Regards,
Deepak

On Thu, Jan 15, 2015 at 4:11 PM, James Dennett <james.dennett at gmail.com>
wrote:

> On Thu, Jan 15, 2015 at 12:51 PM, Deepak Rajendrakumaran <deepak3 at vt.edu>
> wrote:
>
>> Hello,
>>
>> I am new to Clang and so I am having some problem figuring out how to
>> create AST for a program with multiple files .
>>
>>
>> What I am trying to do:
>> - In an application containing multiple .cpp/.c and .h files, parse
>> through all the files and identify all instances of a particular function
>> -Move the function definition to a new file with a changed name(changed
>> function name)
>> -Find all instances where the particular function is called and change
>> the function name to the new name
>>
>> (I am ignoring the other dependencies like nested functions/headers etc
>> so that I can focus on my actual question. So assume this works:))
>>
>> I have been reading up on Clang/libtooling inorder to figure out a way to
>> do the same. From what I understand, the steps to do this would be
>> - Compile and create ASTs for the entire source code(assuming it includes
>> multiple .cpp and .h files)
>> -Somehow traverse these ASTs(RecursiveASTVisitor)  to figure out where
>> all this the particular function I am interested in exists(ASTMatchers??)
>> -First write the function definition to a new file
>> -Now use the rewriter to write the original file without the function
>> definition and replace all the places where a call to this function exists
>> with its new name
>> (I have tried to simplify the problem statement so that I can pinpoint my
>> issue better. I'll ofcourse have to manipulate the ASTs and the source code
>> more to get a working program )
>>
>> First of all, I need to have ASTs of all TUs and not just one AST. Is
>> there any way in libtooling to obtain a single AST for multiple TUs? If not
>> is there any standard practice for the same incase anyone has faced the
>> same problem?
>>
>>
> I'm not sure that I understand.  Standard practice is to process one AST
> per TU.  I've not found it to be a problem, but maybe it is for you for
> some reason -- in which case it might help to say what that reason is.
> There may well be solutions.
>
> -- James
>
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