xo-alloc/include/xo/flatstring/string_view_concat.hpp

30 lines
719 B
C++

#include <string_view>
#include <array>
template <std::string_view const & ... Strings>
struct sv_concat
{
static constexpr auto impl() noexcept {
constexpr std::size_t n = (Strings.size() + ... + 0);
std::array<char, n + 1> arr{};
auto append = [i=0, &arr](const auto & s) mutable {
for (auto c : s)
arr[i++] = c;
};
(append(Strings), ...);
arr[n] = '\0';
return arr;
}
static constexpr auto arr = impl();
static constexpr std::string_view value {
arr.data(),
arr.size() - 1
};
};
template <std::string_view const & ... Strings>
static constexpr auto concat_v = sv_concat<Strings...>::value;