typename boost::enable_if<boost::is_base_of<T, U>, U&>::type
emplace_back(Args&&... args)
{
// the size of the type rounded up to pointer alignment
const int object_size = (sizeof(U) + sizeof(*m_storage) - 1)
/ sizeof(*m_storage);
// +1 for the length prefix
if (m_size + object_size + header_size > m_capacity)
grow_capacity(object_size);
uintptr_t* ptr = m_storage + m_size;
// length prefix
header_t* hdr = reinterpret_cast<header_t*>(ptr);
hdr->len = object_size;
hdr->move = &move<U>;
ptr += header_size;
// construct in-place
new (ptr) U(std::forward<Args>(args)...);
// if we constructed the object without throwing any exception
// update counters to indicate the new item is in there
++m_num_items;
m_size += header_size + object_size;
return *reinterpret_cast<U*>(ptr);
}
/**
* 申请数组空间
* @param v 动态数组
* @param capacity 要申请的元素数量
* @return 空间分配成功与否
*/
bool vector_reserve(vector_t *v, vector_size_t capacity)
{
if (v) {
if (capacity > v->capacity) {
v->capacity = grow_capacity(capacity);
v->data = realloc(v->data, v->len * v->capacity);
return v->data;
}
return true;
}
return false;
}
void mp_int<A,T>::pow2(typename mp_int<A,T>::size_type b)
{
grow_capacity(b / digit_bits + 1);
// set size_ to where the bit will go
size_ = b / digit_bits + 1;
// set all bits to zero
std::memset(digits_, 0, size_ * sizeof(digit_type));
// put the single bit in its place
digits_[b / digit_bits] = digit_type(1) << (b % digit_bits);
}