// -----------
// Classes.c++
// -----------

#include <cassert>  // assert
#include <iostream> // cout, endl

template <typename T>
class A {
    private:
        enum {ev = 2}; // one for all As
        static T cv;   // one for each kind of A
               T iv;   // one for each A

    public:
        A () :
                iv  (4)
            {}

        class B {
            friend class A;

            private:
                enum {ew = 5}; // one for all Bs
                static T cw;   // one for each kind of A
                       T iw;   // one for each B

            public:
                B () :
                        iw  (7)
                    {}

                void g () {
                    assert(ev     == 2);    // A::ev
                    assert(cv     == 3);    // A::cv
//                  assert(iv     == 4);    // doesn't compile
                    assert(ew     == 5);    // B::ew
                    assert(cw     == 6);    // B::cw
                    assert(iw     == 7);}}; // this->iw

        friend class B;

        void f () {
            assert(ev    == 2); // A::ev
            assert(cv    == 3); // A::cv
            assert(iv    == 4); // this->iv
            assert(B::ew == 5);
            assert(B::cw == 6);
//          assert(iw    == 7); // doesn't compile
            }};

template <typename T>
T A<T>::cv = 3;

template <typename T>
T A<T>::B::cw = 6;

int main () {
    using namespace std;
    cout << "Classes.c++" << endl;

    A<int> x;
    x.f();

    A<int>::B y;
    y.g();

    cout << "Done." << endl;
    return 0;}