geode/loader/include/Geode/utils/conststring.hpp

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2022-07-30 12:24:03 -04:00
#pragma once
#include <array>
#include <string_view>
using namespace std::string_view_literals;
namespace geode::utils {
static constexpr const std::string_view sv_null = "\0";
static constexpr const std::string_view sv_none = "";
static constexpr const std::string_view sv_path = "/";
// straight off https://stackoverflow.com/questions/38955940/how-to-concatenate-static-strings-at-compile-time
template <std::string_view const& Separator, std::string_view const&... Strs>
struct ConstStringJoin {
static constexpr auto impl() noexcept {
constexpr std::size_t len = (Strs.size() + ... + 0) + (sizeof...(Strs) - 1) * Separator.size();
std::array<char, len + 1> arr{};
auto append = [len, i = 0, &arr](auto const& s) mutable {
for (auto c : s) arr[i++] = c;
if (i < static_cast<int>(len - 1)) {
for (auto c : Separator) arr[i++] = c;
}
};
(append(Strs), ...);
arr[len] = 0;
return arr;
}
static constexpr auto arr = impl();
static constexpr std::string_view value {arr.data(), arr.size() - 1};
};
template <std::string_view const& Separator, std::string_view const&... Strs>
static constexpr auto const_join_sep = ConstStringJoin<Separator, Strs...>::value;
template <std::string_view const&... Strs>
static constexpr auto const_join = ConstStringJoin<sv_none, Strs...>::value;
template <std::string_view const&... Strs>
static constexpr auto const_join_path = ConstStringJoin<
sv_path, Strs...
>::value;
template <std::string_view const& Separator, std::string_view const&... Strs>
static constexpr const char* const_join_sep_c_str = ConstStringJoin<
Separator, Strs...
>::value.data();
template <std::string_view const&... Strs>
static constexpr const char* const_join_c_str = ConstStringJoin<
sv_none, Strs...
>::value.data();
template <std::string_view const&... Strs>
static constexpr const char* const_join_path_c_str = ConstStringJoin<
sv_path, Strs...
>::value.data();
}