AST of a project by Clang

问题:

I use the Clang python binding to extract the AST of c/c++ files. It works perfectly for a simple program I wrote. The problem is when I want to employ it for a big project like openssl. I can run clang for any single file of the project, but clang seems to miss some headers of the project, and just gives me the AST of a few functions of the file, not all of the functions. I set the include folder by -I, but still getting part of the functions.

This is my code:

import clang.cindex as cl    
cl.Config.set_library_path(clang_lib_dir)
index = cl.Index.create()
lib = 'Path to include folder'
args = ['-I{}'.format(lib)]
translation_unit = index.parse(source_file, args=args)
my_get_info(translation_unit.cursor)

I receive too many header files not found errors.

UPDATE

I used Make to compile openssl by clang? I can pass -emit-ast option to clang to dump the ast of each file, but I cannot read it now by the clang python binding.

Any clues how I can save the the serialized representation of the translation units so that I will be able to read it by index.read()?

Thank you!

回答1:

You would "simply" need to provide the right args. But be aware of two possible issues.

Different files may require different arguments for parsing. The easiest solution is to obtain compilation database and then extract compile commands from it. If you go this way be aware that you would need to filter out the arguments a bit and remove things like -c FooBar.cpp (potentially some others), otherwise you may get something like ASTReadError.

Another issue is that the include paths (-I ...) may be relative to the source directory. I.e., if a file main.cpp compiled from a directory /opt/project/ with -I include/path argument, then before calling index.parse(source_file, args=args) you need to step in (chdir) into the /opt/project, and when you are done you will probably need to go back to the original working directory. So the code may look like this (pseudocode):

cwd = getcwd()
chdir('/opt/project')
translation_unit = index.parse(source_file, args=args)
chdir(cwd)

I hope it helps.