#include "ginac/ginac.h"


using namespace std;


// declare and register (non-commutative) two-argument function TA(...)
DECLARE_FUNCTION_2P(TA)
static GiNaC::ex TA_eval(const GiNaC::ex& p, const GiNaC::ex& d) {
  return dirac_slash(p, d);
}
GiNaC::return_type_t my_type = GiNaC::make_return_type_t<GiNaC::clifford> ();
REGISTER_FUNCTION(TA, eval_func(TA_eval).set_return_type(GiNaC::return_types::noncommutative, &my_type))


// declare and register one argument function OA(...)
DECLARE_FUNCTION_1P(OA)
REGISTER_FUNCTION(OA, dummy())


// declare and register zero argument function ZA() (this should probably no be done)
class ZA_SERIAL { public: static unsigned serial; };
const unsigned ZA_NPARAMS = 0;
template<typename T1> const GiNaC::function ZA() { return GiNaC::function(ZA_SERIAL::serial); }
static GiNaC::ex ZA_eval(const GiNaC::ex& dummy = 0) { // empty argument not accepted
	return 1;
}
unsigned ZA_SERIAL::serial = GiNaC::function::register_new(
		GiNaC::function_options("ZA", ZA_NPARAMS).eval_func(ZA_eval));




int main() {

  using namespace GiNaC;

  symbol p1("p1"), p2("p2"), d("d");


  // bug: parsed product does not respect non-commutativity
  ex dirac1("TA(p1,d) * TA(p2,d)", lst(p1,p2,d));
  ex dirac2("TA(p2,d) * TA(p1,d)", lst(p1,p2,d));
  cout << dirac1 << endl;
  cout << dirac2 << endl;
  cout << dirac1 - dirac2 << endl << endl;


  // bug: parser accepts zero and one argument  
  ex z0("ZA()", lst());
  cout << "ZA(): " << z0 << endl;
  ex z1("ZA(2)", lst());
  cout << "ZA(2): " << z1 << endl << endl;


  // bug: parser accepts zero arguments
  ex a("OA()", lst());
  cout << "OA(): " << a << endl;


  return 0;
}