2. Addition of a new lexeme.

If you want to add a keyword which should be processed, you need to create a new lexeme ("token"). Let's look at the example of adding a new keyword "__w64". At first create an identifier of the new lexeme (see token-name.h file), for example in this way:

enum {	
  Identifier = 258,
  Constant = 262,
  ...
  W64 = 346, // New token name
  ...
};

Modernize the table "table" in lex.cc file:

static rw_table table[] = {
	...
    { "__w64",       W64 },
	...
};

The next step is to create a class for the new lexeme, which we'll call LeafW64.

namespace Opencxx
{
class LeafW64 : public LeafReserved {
public:
  LeafW64(Token& t) : LeafReserved(t) {}
  LeafW64(char* str, ptrdiff_t len) :
     LeafReserved(str, len) {}
  ptrdiff_t What() { return W64; }
};
}

To create an object we'll need to modify optIntegralTypeOrClassSpec() function:

...
case UNSIGNED :
  flag = 'U';
  kw = new (GC) LeafUNSIGNED(tk);
  break;
case W64 : // NEW!
  flag = 'W';
  kw = new (GC) LeafW64(tk);
  break;
...

Pay attention that as far as we've decided to refer "__w64" to data types, we'll need the 'W' symbol for coding this type. You may learn more about type coding mechanism in Encoding.cc file.

Introducing a new type we must remember that we need to modernize such functions as Parser::isTypeSpecifier() for example.

And the last important point is modification of Encoding::MakePtree function:

Ptree* Encoding::MakePtree(unsigned char*& encoded, Ptree* decl)
{
	...
        case 'W' :
            typespec = PtreeUtil::Snoc(typespec, w64_t);
            break;
	...
}

Of course, it is only an example, and adding other lexemes may take much more efforts. A good way to add a new lexeme correctly is to take one close to it in sense and then find and examine all the places in OpenC++ library where it is used.