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#pragma once
#include <type_traits>
#include <concepts>
#include <tuple>
#include "compat/assert.hpp"
namespace floormat::detail_Pack {
template<std::unsigned_integral T, size_t N>
struct Bits final
{
static_assert(std::is_fundamental_v<T>);
static_assert(N > 0);
static_assert(N < sizeof(T)*8);
using type = T;
static constexpr auto bits = N;
};
template<std::unsigned_integral T, size_t CAPACITY>
struct Storage
{
static_assert(CAPACITY <= sizeof(T)*8);
using Type = T;
static constexpr size_t Capacity = CAPACITY;
T value;
template<size_t N>
constexpr T get() const
{
static_assert(N > 0);
static_assert(N <= sizeof(T)*8);
static_assert(N <= Capacity);
return T(value & (T(1) << N) - T(1));
}
template<size_t N>
constexpr T advance() const
{
static_assert(N <= sizeof(T)*8);
static_assert(N <= Capacity);
return T(value >> N);
}
constexpr bool operator==(const Storage&) const noexcept = default;
[[nodiscard]] constexpr inline bool check_zero() const { return value == T(0); }
template<size_t N> using next = Storage<T, Capacity - N>;
};
template<std::unsigned_integral T>
struct Storage<T, 0>
{
using Type = T;
static constexpr size_t Capacity = 0;
T value;
template<size_t N> [[maybe_unused]] constexpr T get() const = delete;
template<size_t N> [[maybe_unused]] constexpr T advance() const = delete;
constexpr bool operator==(const Storage&) const noexcept = default;
[[nodiscard]] constexpr inline bool check_zero() const { return true; }
template<size_t N> struct next
{
static_assert(N == 0, "reading past the end");
static_assert(N != 0, "reading past the end");
};
};
template<std::unsigned_integral T, size_t N>
struct make_tuple_type_
{
template<size_t> using index_to_type = T;
template<typename> struct aux;
template<size_t... Is> struct aux<std::index_sequence<Is...>>
{
static_assert(sizeof...(Is) > 0);
using type = std::tuple<index_to_type<Is>...>;
};
using Seq = typename aux<std::make_index_sequence<N>>::type;
};
template<std::unsigned_integral T, size_t N> using make_tuple_type = typename make_tuple_type_<T, N>::Seq;
template<typename... Ts> struct pack_tuple {};
template<std::unsigned_integral T, typename Place, size_t Left, size_t I, size_t... Is, size_t Size, typename... Sizes>
requires requires() { sizeof...(Is) == sizeof...(Sizes); }
constexpr void assign_tuple(Place& p, Storage<T, Left> st, std::index_sequence<I, Is...>, pack_tuple<Bits<T, Size>, Sizes...>)
{
static_assert(Size <= Left, "too many bits requested");
static_assert(I < std::tuple_size_v<Place>, "too few tuple members");
using S = Storage<T, Left>;
using next_type = typename S::template next<Size>;
get<I>(p) = st.template get<Size>();
T next_value = st.template advance<Size>();
assign_tuple(p, next_type{next_value}, std::index_sequence<Is...>{}, pack_tuple<Sizes...>{});
}
template<std::unsigned_integral T, typename Place, size_t Left>
constexpr void assign_tuple(Place&, Storage<T, Left> st, std::index_sequence<>, pack_tuple<>)
{
fm_assert(st.check_zero());
}
template<std::unsigned_integral T, typename Place, size_t Left, size_t... Is, typename... Sizes>
requires(sizeof...(Is) != sizeof...(Sizes))
constexpr void assign_tuple(Place&, Storage<T, Left>, std::index_sequence<Is...>, pack_tuple<Sizes...>) = delete;
template<std::unsigned_integral T, size_t... Ns> using make_pack = pack_tuple<Bits<T, Ns>...>;
} // namespace floormat::detail_Pack
namespace floormat::Pack {
} // namespace floormat::Pack
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