23.vector.stdcxx-1037.cpp

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#include <cassert>   // for assert()
#include <cstddef>   // for size_t
#include <memory>    // for allocator
#include <vector>    // for vector
 
template <typename T>
struct Alloc : std::allocator<T>
{
    Alloc (int i) : i_ (i) { }
 
    template <typename U> 
    struct rebind {
        typedef Alloc<U> other;
    };
 
    template <typename U>
    Alloc (const Alloc<U>& other)
        : std::allocator<T>(other), i_ (other.i_) { }
 
    template <typename U>
    Alloc& operator= (const Alloc<U>& other)
    {
        std::allocator<T>::operator= (other);
        i_ = other.i_;
        return *this;
    }
 
    int i_;
};
 
template <typename T>
bool operator== (const Alloc<T>& a1, const Alloc<T>& a2)
{
    return a1.i_ == a2.i_;
}
 
int main ()
{
    std::vector<int, Alloc<int> > v1 (Alloc<int> (1));
    v1.push_back (1);
    assert (1 == v1.size () && 1 == v1.front ());
 
    std::vector<int, Alloc<int> > v2( Alloc<int> (2));
    v2.push_back (2);
    assert (1 == v2.size () && 2 == v2.front ());
 
    v1.swap (v2);
 
    assert (1 == v1.size () && 2 == v1.front ());
    assert (1 == v2.size () && 1 == v2.front ());
 
    return 0;
}