From: Sam Roberts <sroberts@...>
Date: 2003-04-27T23:06:01+09:00
Subject: Re: Parsing C++ with Ruby

Quoteing deliriousNOSPAM@atchoo.be, on Sun, Apr 27, 2003 at 07:52:39PM +0900:
> On Sat, 26 Apr 2003 at 16:48 GMT, Sam Roberts wrote:
> > A recent Dr. Dobbs Journal described extensions made to gcc so that it
> > dumps the parsed c or c++ syntax as xml. They did this because existing
> > non-compiler parsers were all aproximations of the c++ syntax, and
> > didnt' work with complex templated c++ code. They used it to build
> > wrappers in some other language (swig-like), but you could use  this to
> > get an xml representation of the code, and then your dotfile generator
> > would only have to parse xml, for which there are many tools.
> 
> I had never heard about this, very interesting.
> 
> Am I to gather from your answer that you do not recommend trying to
> match multi-line C++ expressions with Ruby. 

I haven't coded in C++ in years, but I tried to write a parser for it
once, and things like this are hard to parse:

template<class T = Hash<Obj<int> > > Foo(T t, int max = 19);

Even if it wasn't hard, there's no way it would be as easy to parse
as xml, where there are lots of mature toolkits. Say it "only" takes
you 10 hours... thats 10 hours you could have spent doing something
cool thats never been done before!

From gccxml.org:

  Development tools that work with programming languages benefit from
  their ability to understand the code with which they work       at a
  level comparable to a compiler. C++ has become a popular       and
  powerful language, but parsing it is a very challenging       problem.
  This has discouraged the development of tools meant to       work
  directly with the language.     

  There is one open-source C++ parser, the C++ front-end to GCC, which is
  currently able to deal with the language in its entirety.  The purpose
  of the GCC-XML extension is to generate an XML description of a C++
  program from GCC's internal representation. Since XML is easy to parse,
  other development tools will be able to work with C++ programs without
  the burden of a complicated C++ parser.