gibsonca:

John's response shows many of the shortcomings of working on the source code. However, if the code already exists, then it presumably compiles. Perhaps you can parse the debugging information of the compiled object or executable files. The output of objdump is rather arcane, but looks regular enough to more easily parse than the original source code. Other compilers may have other debug or cross-reference output that you may find easier to handle.

...roboticus

When your only tool is a hammer, all problems look like your thumb.