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Revert addition of the default-initializing tuple (poor compiler supp…
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…ort)
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@eliaskosunen
eliaskosunen committed May 22, 2024
1 parent f406e40 commit 40de0a9
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Showing 2 changed files with 16 additions and 103 deletions.
118 changes: 15 additions & 103 deletions include/scn/scan.h
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Original file line number Diff line number Diff line change
Expand Up @@ -3611,94 +3611,6 @@ constexpr auto make_string_view_iterator_from_pointer(
}
}

/////////////////////////////////////////////////////////////////
// Simple default-initializing, non-copyable/movable tuple
/////////////////////////////////////////////////////////////////

template <size_t I, typename T>
struct tuple_leaf {
tuple_leaf() = default;

tuple_leaf(T&& val) : value(SCN_MOVE(val)) {}

tuple_leaf(const tuple_leaf&) = delete;
tuple_leaf& operator=(const tuple_leaf&) = delete;
tuple_leaf(tuple_leaf&&) = delete;
tuple_leaf& operator=(tuple_leaf&&) = delete;
~tuple_leaf() = default;

// default-initialized on purpose
T value;
};

template <size_t I, typename... Items>
struct tuple_impl;

template <size_t I>
struct tuple_impl<I> {};

template <size_t I, typename Head, typename... Tail>
struct tuple_impl<I, Head, Tail...> : tuple_leaf<I, Head>,
tuple_impl<I + 1, Tail...> {
tuple_impl() = default;

tuple_impl(Head&& h, Tail&&... t)
: tuple_leaf<I, Head>(SCN_MOVE(h)),
tuple_impl<I + 1, Tail...>(SCN_MOVE(t)...)
{
}
};

template <size_t I, typename Head, typename... Tail>
Head& tuple_get(tuple_impl<I, Head, Tail...>& tuple)
{
return tuple.template tuple_leaf<I, Head>::value;
}

template <typename... Ts>
using tuple = tuple_impl<0, Ts...>;

template <typename Tuple>
struct tuple_size;
template <typename... Ts>
struct tuple_size<tuple<Ts...>>
: std::integral_constant<size_t, sizeof...(Ts)> {};

template <size_t... Is>
auto index_over(std::index_sequence<Is...>)
{
return [](auto&& f) -> decltype(auto) {
return SCN_FWD(f)(std::integral_constant<size_t, Is>{}...);
};
}

template <typename F, typename Tuple>
decltype(auto) tuple_apply(F&& f, Tuple&& tup)
{
constexpr size_t sz = tuple_size<remove_cvref_t<Tuple>>::value;
auto indexer = index_over(std::make_index_sequence<sz>{});
return indexer([&](auto... Is) -> decltype(auto) {
return std::forward<F>(f)(tuple_get<Is>(std::forward<Tuple>(tup))...);
});
}

template <typename... Ts>
std::tuple<Ts...> to_std_tuple(tuple<Ts...>&& tup)
{
auto indexer = index_over(std::make_index_sequence<sizeof...(Ts)>{});
return indexer([&](auto... Is) -> std::tuple<Ts...> {
return {SCN_MOVE(tuple_get<Is>(tup))...};
});
}

template <typename... Ts>
detail::tuple<Ts...> from_std_tuple(std::tuple<Ts...>&& tup)
{
return std::apply(
[&](Ts&&... vals) { return detail::tuple<Ts...>(SCN_MOVE(vals)...); },
SCN_MOVE(tup));
}

/////////////////////////////////////////////////////////////////
// Lightweight Unicode facilities
/////////////////////////////////////////////////////////////////
Expand Down Expand Up @@ -5217,13 +5129,13 @@ struct scan_arg_store;
template <typename Context, typename... Args>
struct scan_arg_store<scan_arg_store_kind::builtin, Context, Args...> {
constexpr scan_arg_store()
: data(detail::tuple_apply(make_data_array<Args...>, args))
: data(std::apply(make_data_array<Args...>, args))
{
}

constexpr scan_arg_store(std::tuple<Args...>&& d)
: args(detail::from_std_tuple(SCN_MOVE(d))),
data(detail::tuple_apply(make_data_array<Args...>, args))
: args(SCN_MOVE(d)),
data(std::apply(make_data_array<Args...>, args))
{
}

Expand All @@ -5246,28 +5158,28 @@ struct scan_arg_store<scan_arg_store_kind::builtin, Context, Args...> {

constexpr auto get_tuple() &&
{
return detail::to_std_tuple(SCN_MOVE(args));
return SCN_MOVE(args);
}

static constexpr scan_arg_store_kind kind = scan_arg_store_kind::builtin;
static constexpr size_t desc =
encode_types<typename Context::char_type, Args...>() |
is_builtin_only_bit;

detail::tuple<Args...> args;
std::tuple<Args...> args;
std::array<void*, sizeof...(Args)> data;
};

template <typename Context, typename... Args>
struct scan_arg_store<scan_arg_store_kind::packed, Context, Args...> {
constexpr scan_arg_store()
: data(detail::tuple_apply(make_data_array<Args...>, args))
: data(std::apply(make_data_array<Args...>, args))
{
}

constexpr scan_arg_store(std::tuple<Args...>&& d)
: args(detail::from_std_tuple(SCN_MOVE(d))),
data(detail::tuple_apply(make_data_array<Args...>, args))
: args(SCN_MOVE(d)),
data(std::apply(make_data_array<Args...>, args))
{
}

Expand All @@ -5291,27 +5203,27 @@ struct scan_arg_store<scan_arg_store_kind::packed, Context, Args...> {

constexpr auto get_tuple() &&
{
return detail::to_std_tuple(SCN_MOVE(args));
return SCN_MOVE(args);
}

static constexpr scan_arg_store_kind kind = scan_arg_store_kind::packed;
static constexpr size_t desc =
encode_types<typename Context::char_type, Args...>();

detail::tuple<Args...> args;
std::tuple<Args...> args;
std::array<arg_value, sizeof...(Args)> data;
};

template <typename Context, typename... Args>
struct scan_arg_store<scan_arg_store_kind::unpacked, Context, Args...> {
constexpr scan_arg_store()
: data(detail::tuple_apply(make_data_array<Args...>, args))
: data(std::apply(make_data_array<Args...>, args))
{
}

constexpr scan_arg_store(std::tuple<Args...>&& d)
: args(detail::from_std_tuple(SCN_MOVE(d))),
data(detail::tuple_apply(make_data_array<Args...>, args))
: args(SCN_MOVE(d)),
data(std::apply(make_data_array<Args...>, args))
{
}

Expand All @@ -5335,13 +5247,13 @@ struct scan_arg_store<scan_arg_store_kind::unpacked, Context, Args...> {

constexpr auto get_tuple() &&
{
return detail::to_std_tuple(SCN_MOVE(args));
return SCN_MOVE(args);
}

static constexpr scan_arg_store_kind kind = scan_arg_store_kind::unpacked;
static constexpr size_t desc = is_unpacked_bit | sizeof...(Args);

detail::tuple<Args...> args;
std::tuple<Args...> args;
std::array<basic_scan_arg<Context>, sizeof...(Args)> data;
};

Expand Down
1 change: 1 addition & 0 deletions tests/unittests/args_test.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -86,4 +86,5 @@ TEST(ArgsTest, ArgStore)

auto tup = std::move(store).get_tuple();
EXPECT_EQ(std::get<0>(tup), 42);
EXPECT_DOUBLE_EQ(std::get<1>(tup), 0.0);
}

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