vector.h
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#ifndef __VECTOR_H__
#define __VECTOR_H__
#include <cstring>
#include <limits>
#include <type_traits>
template <class C> class vector {
C* data;
unsigned int size;
unsigned int cap;
private:
static unsigned int round_up_to_power_of_2(unsigned w)
{
constexpr auto bits = std::numeric_limits<unsigned>::digits;
--w;
for (unsigned s = 1; s < bits; s *= 2)
w |= w >> s;
return ++w;
};
void destroy_array(C* ptr, unsigned int s)
{
for (unsigned j = 0; j < s; ++j)
(ptr + j)->~C();
free(ptr);
}
void resize_before_push()
{
if (size >= cap) {
if (cap >
std::numeric_limits<decltype(size)>::max() / (2 * sizeof(C)))
throw std::length_error("Vector too long");
unsigned int newcap = (cap == 0) ? 1 : 2 * cap;
C* newdata;
if constexpr (!std::is_trivially_copyable<C>()) {
newdata = static_cast<C*>(
std::aligned_alloc(alignof(C), newcap * sizeof(C)));
if (!newdata)
throw bad_alloc();
unsigned i;
try {
for (i = 0; i < size; i++)
if constexpr (noexcept(C(std::move(data[i]))))
new (newdata + i) C(std::move(data[i]));
else
new (newdata + i) C(data[i]);
}
catch (...) {
destroy_array(newdata, i);
throw;
}
destroy_array(data, size);
}
else {
newdata =
static_cast<C*>(std::realloc(data, newcap * sizeof(C)));
if (!newdata)
throw bad_alloc();
}
data = newdata;
cap = newcap;
}
}
public:
class index_out_of_range {};
explicit vector(unsigned s)
{
cap = round_up_to_power_of_2(s);
data = static_cast<C*>(std::aligned_alloc(alignof(C), cap * sizeof(C)));
if (!data)
throw bad_alloc();
size = s;
unsigned i;
try {
for (i = 0; i < size; i++)
new (data + i) C();
}
catch (...) {
destroy_array(data, i);
throw;
}
}
~vector()
{
destroy_array(data, size);
}
C& operator[](unsigned int pos)
{
if (pos >= size)
throw index_out_of_range();
return data[pos];
}
C operator[](unsigned int pos) const
{
if (pos >= size)
throw index_out_of_range();
return data[pos];
}
vector(const vector<C>& s)
{
cap = s.cap;
data = static_cast<C*>(std::aligned_alloc(alignof(C), cap * sizeof(C)));
if (!data)
throw bad_alloc();
size = s.size;
unsigned i;
try {
for (i = 0; i < size; i++)
new (data + i) C(s.data[i]);
}
catch (...) {
destroy_array(data, i);
throw;
}
}
void swap(vector<C>& s) noexcept
{
C* t1 = s.data;
unsigned int t2 = s.size;
unsigned int t3 = s.cap;
s.data = data;
s.size = size;
data = t1;
size = t2;
cap = t3;
}
vector<C>& operator=(const vector<C>& s)
{
if (this == &s)
return *this;
vector<C> n(s);
swap(n);
return *this;
}
friend ostream& operator<<(ostream& o, const vector<C>& v)
{
o << '[';
for (unsigned i = 0; i < v.size; i++) {
o << v[i];
if (i != v.size - 1)
o << ',';
};
o << ']';
return o;
}
template <class... Args> C& emplace_back(Args&&... args)
{
// cout << "emplace_back" << endl;
resize_before_push();
new (data + size) C(std::forward<Args>(args)...);
return *(data + size++);
}
template <class T> C& push_back(T&& s)
{
resize_before_push();
new (data + size) C(std::forward<T>(s));
return *(data + size++);
}
template <class... Args> C& push_back(Args&&... args)
{
return (push_back(std::forward<Args>(args)), ...);
}
};
#endif /* __VECTOR_H__ */