Method emplace

common/unordered_inline_set.h:86–97

    }
    template<typename...Xs>
    void emplace(size_t i, Xs&&...xs) {
        assert(i < _capacity);
        if (!get_bit(i)) {
            // _ptr[i].T(std::forward<Xs>(xs)...);      // these 2 forms should be almost equal, except
            new (_ptr + i) T(std::forward<Xs>(xs)...);  // this is compatible with basic types, like int, etc.
            set_bit(i);
            _size++;
        } else {
            _ptr[i].~T();
            new (_ptr + i) T(std::forward<Xs>(xs)...);
        }
    }
    const T* get(size_t i) const noexcept { return _get(i); }
    T* get(size_t i) noexcept { return (T*)_get(i); }
    void erase(size_t i) {