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#include <iostream>
#define pvector Vector
using namespace std;
template <class T> class My_allocator {
public:
T allocate(int n); // allocate space for n objects of type T
void deallocate(T p, int n); // deallocate n objects of type T starting at p
void construct(T p, const T& v); // construct a T with the value v in p
void destroy(T p); // destroy the T in p
};
//-------------------------------------------------
template<class T>
T My_allocator<T>::allocate(int n)
{
T p = (T)malloc(sizeof(T)*n);
return p;
}
//------------------------------
template<class T>
void My_allocator<T>::deallocate(T p, int n)
{
free(p);
}
//------------------------------
template<class T>
void My_allocator<T>::construct(T p, const T& v)
{
p = new (p) T(v);
}
//------------------------------
template<class T>
void My_allocator<T>::destroy(T p)
{
p->~T();
}
//------------------------------------------------
class Range_error : out_of_range {
public:
int index;
Range_error(int i) :out_of_range("Range error"), index(i) {}
};
//--------------------------------------------------
template <class T, class A = My_allocator<T> >
class pvector {
A alloc;
int sz, space;
T elem;
public:
pvector() :sz(0), space(0), elem(nullptr) {}
pvector(int n) :sz(n), space(n) { elem = alloc.allocate(n); initial(); }
pvector(int n, const T& v) :sz(n), space(n) { elem = alloc.allocate(n); initial(v); }
pvector<T>& operator=(const pvector<T>); // Copy assignment
// Copy constructor
int size() const { return sz; }
int capacity() const { return space; }
void initial();
void resize(int, T);
void push_back(const T&);
void reserve(int);
T& operator[](unsigned int n) // rather than return at(i);
{
if (n < 0 || this->sz <= n) throw Range_error(n);
return elem[n];
}
const T& operator[](unsigned int n) const
{
if (n < 0 || this->sz <= n) throw Range_error(n);
return elem[n];
}
~pvector() { delete elem; } // Destructor
};
//------------------------------------------------
template<class T, class A>
pvector<T>& pvector<T, A>::operator=(const pvector<T> a)
{
if (a.size() <= space) {
for (int i = 0; i < a.size(); ++i)
elem[i] = a.elem[i];
sz = a.size();
return *this;
}
else if (a.size() > space) {
T* p = alloc.allocate(a.size());
for (int i = 0; i < sz; ++i) alloc.construct(&p[i], a.elem[i]);
for (int i = 0; i < sz; ++i) alloc.destroy(&elem[i]);
alloc.deallocate(elem, space);
elem = p;
space = sz = a.size();
return *this;
}
}
//---------------------------------------------
template<class T, class A>
void pvector<T, A>::initial()
{
for (int i = 0; i < sz; ++i)
elem[i] = 0;
}
//-------------------------------------------
template <class T, class A>
void pvector<T, A>::resize(int newsize, T val = T())
{
reserve(newsize);
for (int i = sz; i < newsize; ++i) alloc.construct(&elem[i], val); // construct
for (int i = newsize; i < sz; ++i) alloc.destroy(&elem[i]); // destroy
sz = newsize;
}
//--------------------------------------------
template <class T, class A>
void pvector<T, A>::push_back(const T& val)
{
if (space == 0) reserve(8);
else if (sz == space) reserve(2 * space);
alloc.construct(&elem[sz], val);
++sz;
}
//--------------------------------------
template <class T, class A>
void pvector<T, A>::reserve(int newalloc)
{
if (newalloc <= space) return;
T* p = alloc.allocate(newalloc);
for (int i = 0; i < sz; ++i) alloc.construct(&p[i], elem[i]);
for (int i = 0; i < sz; ++i) alloc.destroy(&elem[i]);
alloc.deallocate(elem, space);
elem = p;
space = newalloc;
}
//----------------------------------
int main() {
int i = 5;
int* pi = &i;
pvector<int*> v1;
v1.push_back(pi);
*v1[0] = 10;
cout << v1.size() << ' ' << v1.capacity() << ' '
<< *v1[0] << ' ' << v1[0] << ' ' << endl;
pvector<int*> v2(3);
cout << v2.size() << ' ' << v2.capacity() << ' '
<< *v2[0] << ' ' << v2[0] << ' ' << endl;
system("pause");
return 0;
}
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