`GF2::Vector` — Alter the Capacity

Potentially change the capacity of a bit-vector.

constexpr Vector &reserve(std::size_t n);     (1)
constexpr Vector &shrink_to_fit();          (2)

1	Increases the bit-vector’s `capacity` so it can hold `n` elements. Does nothing if `n` fits inside the current capacity.
2	This is a request to minimize the unused/excess `capacity`. May do nothing.

The idea is to make it as efficient as possible to append a (known) large number of elements to a bit-vector by allocating the needed storage up-front rather than in pieces.

These methods both return *this so you can chain them with other calls.

These methods do not change the size() of a bit-vector. No elements are added or deleted.

If the capacity does change, all the old values are unaltered, however, references will be invalidated.

Example

#include <GF2/GF2.h>
int main()
{
    GF2::Vector<> v("10101010");
    std::cout << v << ": size " << v.size() << ", capacity " << v.capacity() << '\n';   (1)
    v.reserve(99);                                                                      (2)
    std::cout << v << ": size " << v.size() << ", capacity " << v.capacity() << '\n';   (3)
    v.shrink_to_fit();                                                                  (4)
    std::cout <<  v << ": size " << v.size() << ", capacity " << v.capacity() << '\n';
}

1	We’re using the default 64-bit blocks so `v` can hold 64 elements (though it only has 8 at present).
2	Get `v` "ready" to hold a total of 99 elements.
3	Given the blocks are all 64-bits long we need 2 of them for those 99 elements so the capacity actually increases to 128.
4	Changed our mind and just want to shrink `v` to minimum size. Note that the elements in `v` never changed!

Output

10101010: size 8, capacity 64
10101010: size 8, capacity 128
10101010: size 8, capacity 64

GF2::Vector — Alter the Capacity

`GF2::Vector` — Alter the Capacity