A garbage collection framework for C++

#include "gcptr.h"
#include <string>
#include <iostream>

//#define	MANUAL_COLLECT
//#define	COLLECT_ON_NEW

using namespace std;

struct b1
{
	b1(const string& s) : name(s)
	{
		cout << "Creating b1(" << name << ")." << endl;
	}
	virtual ~b1()
	{
		cout << "Destroying b1(" << name << ")." << endl;
	}

	string name;
};

struct b2
{
	b2(const string& s) : name(s)
	{
		cout << "Creating b2(" << name << ")." << endl;
	}
	virtual ~b2()
	{
		cout << "Destroying b2(" << name << ")." << endl;
	}

	string name;
};

struct d1 : public b1
{
	d1(const string& s) : b1(s)
	{
		cout << "Creating d1(" << name << ")." << endl;
	}
	virtual ~d1()
	{
		cout << "Destroying d1(" << name << ")." << endl;
	}
};

struct d2 : public b1, public b2
{
	d2(const string& s) : b1(s), b2(s)
	{
		cout << "Creating d2(" << b1::name << ")." << endl;
	}
	virtual ~d2()
	{
		cout << "Destroying d2(" << b1::name << ")." << endl;
	}
};

struct circ
{
	circ(const string& s) : name(s)
	{
		cout << "Creating circ(" << name << ")." << endl;
	}
	~circ()
	{
		cout << "Destroying circ(" << name << ")." << endl;
	}

	gc_ptr<circ> ptr;

	string name;
};

void test()
{
	gc_ptr<b1> p1;

	{
		gc_ptr<d1> p2(new(gc) d1("first"));
		p1 = p2;
		gc_ptr<b1> p3(new(gc) d2("second"));
#ifdef	MANUAL_COLLECT
		gc_collect();
#endif
	}
#ifdef	MANUAL_COLLECT
	gc_collect();
#endif

	{
		gc_ptr<circ> p4(new(gc) circ("root"));
		{
			gc_ptr<circ> p5(new(gc) circ("first"));
			gc_ptr<circ> p6(new(gc) circ("second"));
			gc_ptr<circ> p7(new(gc) circ("third"));

			p4->ptr = p5;
			p5->ptr = p6;
			p6->ptr = p7;
			p7->ptr = p5;
#ifdef	MANUAL_COLLECT
			gc_collect();
#endif
		}
#ifdef	MANUAL_COLLECT
		gc_collect();
#endif
	}
#ifdef	MANUAL_COLLECT
	gc_collect();
#endif
}

int main()
{
#ifdef	COLLECT_ON_NEW
	gc_set_threshold(0);
#endif

	test();
	gc_collect();
	return 0;
}