Good tools for creating a C/C++ parser/analyzer [c

Question

What are some good tools for getting a quick start for parsing and analyzing C/C++ code?

In particular, I'm looking for open source tools that handle the C/C++ preprocessor and language. Preferably, these tools would use lex/yacc (or flex/bison) for the grammar, and not be too complicated. They should handle the latest ANSI C/C++ definitions.

Here's what I've found so far, but haven't looked at them in detail (thoughts?):

• CScope - Old-school C analyzer. Doesn't seem to do a full parse, though. Described as a glorified 'grep' for finding C functions.
• GCC - Everybody's favorite open source compiler. Very complicated, but seems to do it all. There's a related project for creating GCC extensions called GEM, but hasn't been updated since GCC 4.1 (2006).
• PUMA - The PUre MAnipulator. (from the page: "The intention of this project is to provide a library of classes for the analysis and manipulation of C/C++ sources. For this purpose PUMA provides classes for scanning, parsing and of course manipulating C/C++ sources."). This looks promising, but hasn't been updated since 2001. Apparently PUMA has been incorporated into AspectC++, but even this project hasn't been updated since 2006.
• Various C/C++ raw grammars. You can get c-c++-grammars-1.2.tar.gz, but this has been unmaintained since 1997. A little Google searching pulls up other basic lex/yacc grammars that could serve as a starting place.
• Any others?

I'm hoping to use this as a starting point for translating C/C++ source into a new toy language.

Thanks! -Matt

(Added 2/9): Just a clarification: I want to extract semantic information from the preprocessor in addition to the C/C++ code itself. I don't want "#define foo 42" to disappear into the integer "42", but remain attached to the name "foo". This, unfortunately, excludes several solutions that run the preprocessor first and only deliver the C/C++ parse tree)

Answer 1

You can look at clang that uses llvm for parsing.

Support C++ fully now link

Answer 2

See our C++ Front End for a full-featured C++ parser: builds ASTs, symbol tables, does name and type resolution. You can even parse and retain the preprocessor directives. The C++ front end is built on top of our DMS Software Reengineering Toolkit, which allows you to use that information to carry out arbitrary source code changes using source-to-source transformations.

DMS is the ideal engine for implementing such a translator.

Having said that, I don't see much point in your imagined task; I don't see much value in trying to replace C++, and you'll find building a complete translator an enormous amount of work, especially if your target is a "toy" language. And there is likely little point in parsing C++ using a robust parser, if its only purpose is to produce an isomorphic version of C++ that is easier to parse (wait, we postulated a robust C++ already!).

EDIT May 2012: DMS's C++ front end now handles GCC3/GCC4/C++11,Microsoft VisualC 2005/2010. Robustly.

EDIT Feb 2015: Now handles C++14 in GCC and MS dialects.

EDIT August 2015: Now parses and captures both the code and the preprocessor directives in a unified tree.

Answer 3

Parsing C++ is extremely hard because the grammar is undecidable. To quote Yossi Kreinin:

Outstandingly complicated grammar

"Outstandingly" should be interpreted literally, because all popular languages have context-free (or "nearly" context-free) grammars, while C++ has undecidable grammar. If you like compilers and parsers, you probably know what this means. If you're not into this kind of thing, there's a simple example showing the problem with parsing C++: is AA BB(CC); an object definition or a function declaration? It turns out that the answer depends heavily on the code before the statement - the "context". This shows (on an intuitive level) that the C++ grammar is quite context-sensitive.

Answer 4

Depending on your problem GCCXML might be your answer. Basically it parses the source using GCC and then gives you easily digestible XML of parse tree. With GCCXML you are done once and for all.

Answer 5

The ANTLR parser generator has a grammar for C/C++ as well as the preprocessor. I've never used it so I can't say how complete its parsing of C++ is going to be. ANTLR itself has been a useful tool for me on a couple of occasions for parsing much simpler languages.

Answer 6

The grammar for C++ is sort of notoriously hairy. There's a good thread at Lambda about it, but the gist is that C++ grammar can require arbitrarily much lookahead.

For the kind of thing I imagine you might be doing, I'd think about hacking either Gnu CC, or Splint. Gnu CC in particular does separate out the language generation part pretty thoroughly, so you might be best off building a new g++ backend.