// type_of() evil implementation for VC7
//
// (c) Chez
// mailto:chezu@pisem.net

#include "stdafx.h"

// This file contains:
// 1) type_id(type)
// 2) var_type_id(expersssion)
// 3) type_of(expression)

// IMPLEMENTATION
template<int ID>
class CTypeRegRoot
{
public:
    class id2type;
};

template<typename T, int ID>
class CTypeReg : public CTypeRegRoot<ID>
{
public:
    class CTypeRegRoot<ID>::id2type // This uses nice VC6-VC7 bugfeature
    {
    public:
        typedef T Type;
    };

    typedef void Dummy;
};

template<int N>
class CCounter;

// TUnused is required to force compiler to recompile CCountOf class
template<typename TUnused, int NTested = 0>
class CCountOf
{
public:
    enum
    {
        __if_exists(CCounter<NTested>) { count = CCountOf<TUnused, NTested + 1>::count }
        __if_not_exists(CCounter<NTested>) { count = NTested }
    };
};

template<class TTypeReg, class TUnused, int NValue> // Helper class
class CProvideCounterValue
{
public:
    enum { value = NValue };
};

// type_id
#define type_id(type) \
    (CProvideCounterValue< \
        /*register TYPE--ID*/ typename CTypeReg<type, CCountOf<type >::count>::Dummy, \
        /*increment compile-time Counter*/ CCounter<CCountOf<type >::count>, \
        /*pass value of Counter*/CCountOf<type >::count \
     >::value)

// Lets type_id() be > than 0
class __Increment_type_id { enum { value = type_id(__Increment_type_id) }; };

template<int NSize>
class sized
{
private:
    char m_pad[NSize];
};

template<typename T>
typename sized<type_id(T)> VarTypeID(T&);
template<typename T>
typename sized<type_id(const T)> VarTypeID(const T&);
template<typename T>
typename sized<type_id(volatile  T)> VarTypeID(volatile T&);
template<typename T>
typename sized<type_id(const volatile T)> VarTypeID(const volatile T&);

// Unfortunatelly, var_type_id() does not recognize references
#define var_type_id(var) \
    (sizeof(VarTypeID(var)))
    
// type_of
#define type_of(expression) \
    /* This uses nice VC6-VC7 bugfeature */ \
    CTypeRegRoot<var_type_id(expression)>::id2type::Type

// auto_operator
#define auto_operator(arg1, arg2, op) \
    type_of(instance(arg1) op instance(arg2)) operator op


// TEST    
class A
{
public:
    friend static const char* operator +(const A& a, const A& b)
    {
        return "chijik-pijik";
    }
};

template<typename T>
class Plus
{
public:
    friend static type_of(T() + T()) operator +(const Plus<T>& a, const Plus<T>& b)
    {
        return a.m + b.m;
    }

    T m;
};

int _tmain(int argc, _TCHAR* argv[])
{
    Plus<A> a1, a2;
    const char* x = a1 + a2;

    return 0;
}