Castable: Optimize Switch()

Use a bloom-filter-style early rejection to eliminate whole blocks of
case statements from the switch type checks. Much like IsAnyOf(), the
list of types considered are recursively tested as a whole and
then binary-chopped if there's a potential match, until we test the
individual switch case types.

Bug: tint:1383
Change-Id: I5b30f19ea070e8352bf6b9363f133da906013182
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78544
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
This commit is contained in:
Ben Clayton 2022-02-04 18:58:33 +00:00 committed by Tint LUCI CQ
parent b3c99ddfae
commit 3fbe98e657
3 changed files with 232 additions and 128 deletions

View File

@ -465,6 +465,131 @@ class Castable : public BASE {
/// ```
struct Default {};
namespace detail {
/// Evaluates to the Switch case type being matched by the switch case function
/// `FN`.
/// @note does not handle the Default case
/// @see Switch().
template <typename FN>
using SwitchCaseType = std::remove_const_t<std::remove_pointer_t<
traits::ParameterType<std::remove_reference_t<FN>, 0>>>;
/// Evaluates to true if the function `FN` has the signature of a Default case
/// in a Switch().
/// @see Switch().
template <typename FN>
inline constexpr bool IsDefaultCase =
std::is_same_v<traits::ParameterType<std::remove_reference_t<FN>, 0>,
Default>;
/// Searches the list of Switch cases for a Default case, returning the index of
/// the Default case. If the a Default case is not found in the tuple, then -1
/// is returned.
template <typename TUPLE, std::size_t START_IDX = 0>
constexpr int IndexOfDefaultCase() {
if constexpr (START_IDX < std::tuple_size_v<TUPLE>) {
return IsDefaultCase<std::tuple_element_t<START_IDX, TUPLE>>
? static_cast<int>(START_IDX)
: IndexOfDefaultCase<TUPLE, START_IDX + 1>();
} else {
return -1;
}
}
/// The implementation of Switch() for non-Default cases.
/// Switch splits the cases into two a low and high block of cases, and quickly
/// rules out blocks that cannot match by comparing the TypeInfo::HashCode of
/// the object and the cases in the block. If a block of cases may match the
/// given object's type, then that block is split into two, and the process
/// recurses. When NonDefaultCases() is called with a single case, then As<>
/// will be used to dynamically cast to the case type and if the cast succeeds,
/// then the case handler is called.
/// @returns true if a case handler was found, otherwise false.
template <typename T, typename RETURN_TYPE, typename... CASES>
inline bool NonDefaultCases(T* object,
const TypeInfo* type,
RETURN_TYPE* result,
std::tuple<CASES...>&& cases) {
using Cases = std::tuple<CASES...>;
(void)result; // Not always used, avoid warning.
static constexpr bool kHasReturnType = !std::is_same_v<RETURN_TYPE, void>;
static constexpr size_t kNumCases = sizeof...(CASES);
if constexpr (kNumCases == 0) {
// No cases. Nothing to do.
return false;
} else if constexpr (kNumCases == 1) { // NOLINT: cpplint doesn't understand
// `else if constexpr`
// Single case.
using CaseFunc = std::tuple_element_t<0, Cases>;
static_assert(!IsDefaultCase<CaseFunc>,
"NonDefaultCases called with a Default case");
// Attempt to dynamically cast the object to the handler type. If that
// succeeds, call the case handler with the cast object.
using CaseType = SwitchCaseType<CaseFunc>;
if (auto* ptr = As<CaseType>(object)) {
if constexpr (kHasReturnType) {
*result = std::get<0>(cases)(ptr);
} else {
std::get<0>(cases)(ptr);
}
return true;
}
return false;
} else {
// Multiple cases.
// Check the hashcode bits to see if there's any possibility of a case
// matching in these cases. If there isn't, we can skip all these cases.
if (type->full_hashcode &
TypeInfo::CombinedHashCodeOf<SwitchCaseType<CASES>...>()) {
// There's a possibility. We need to scan further.
// Split the cases into two, and recurse.
constexpr size_t kMid = kNumCases / 2;
return NonDefaultCases(object, type, result,
traits::Slice<0, kMid>(cases)) ||
NonDefaultCases(object, type, result,
traits::Slice<kMid, kNumCases - kMid>(cases));
} else {
return false;
}
}
}
/// The implementation of Switch() for all cases.
/// @see NonDefaultCases
template <typename T, typename RETURN_TYPE, typename... CASES>
inline void SwitchCases(T* object,
const TypeInfo* type,
RETURN_TYPE* result,
std::tuple<CASES...>&& cases) {
using Cases = std::tuple<CASES...>;
static constexpr int kDefaultIndex = detail::IndexOfDefaultCase<Cases>();
static_assert(kDefaultIndex == -1 || std::tuple_size_v<Cases> - 1,
"Default case must be last in Switch()");
static constexpr bool kHasDefaultCase = kDefaultIndex >= 0;
static constexpr bool kHasReturnType = !std::is_same_v<RETURN_TYPE, void>;
if constexpr (kHasDefaultCase) {
// Evaluate non-default cases.
if (!detail::NonDefaultCases<T>(object, type, result,
traits::Slice<0, kDefaultIndex>(cases))) {
// Nothing matched. Evaluate default case.
if constexpr (kHasReturnType) {
*result = std::get<kDefaultIndex>(cases)({});
} else {
std::get<kDefaultIndex>(cases)({});
}
}
} else {
detail::NonDefaultCases<T>(object, type, result, std::move(cases));
}
}
} // namespace detail
/// Switch is used to dispatch one of the provided callback case handler
/// functions based on the type of `object` and the parameter type of the case
/// handlers. Switch will sequentially check the type of `object` against each
@ -493,62 +618,26 @@ struct Default {};
/// ```
///
/// @param object the object who's type is used to
/// @param first_case the first switch case
/// @param other_cases additional switch cases (optional)
/// @param cases the switch cases
/// @return the value returned by the called case. If no cases matched, then the
/// zero value for the consistent case type.
template <typename T, typename FIRST_CASE, typename... OTHER_CASES>
traits::ReturnType<FIRST_CASE> //
Switch(T* object, FIRST_CASE&& first_case, OTHER_CASES&&... other_cases) {
using ReturnType = traits::ReturnType<FIRST_CASE>;
using CaseType = std::remove_pointer_t<traits::ParameterType<FIRST_CASE, 0>>;
template <typename T, typename... CASES>
inline auto Switch(T* object, CASES&&... cases) {
using Cases = std::tuple<CASES...>;
using ReturnType = traits::ReturnType<std::tuple_element_t<0, Cases>>;
static constexpr bool kHasReturnType = !std::is_same_v<ReturnType, void>;
static_assert(traits::SignatureOfT<FIRST_CASE>::parameter_count == 1,
"Switch case must have a single parameter");
if constexpr (std::is_same_v<CaseType, Default>) {
// Default case. Must be last.
(void)object; // 'object' is not used by the Default case.
static_assert(sizeof...(other_cases) == 0,
"Switch Default case must come last");
auto& type = object->TypeInfo();
if constexpr (kHasReturnType) {
return first_case({});
} else {
first_case({});
return;
}
} else {
// Regular case.
static_assert(traits::IsTypeOrDerived<CaseType, CastableBase>::value,
"Switch case parameter is not a Castable pointer");
// Does the case match?
if (auto* ptr = As<CaseType>(object)) {
if constexpr (kHasReturnType) {
return first_case(ptr);
} else {
first_case(ptr);
return;
}
}
// Case did not match. Got any more cases to try?
if constexpr (sizeof...(other_cases) > 0) {
// Try the next cases...
if constexpr (kHasReturnType) {
auto res = Switch(object, std::forward<OTHER_CASES>(other_cases)...);
static_assert(std::is_same_v<decltype(res), ReturnType>,
"Switch case types do not have consistent return type");
ReturnType res = {};
detail::SwitchCases(object, &type, &res,
std::forward_as_tuple(std::forward<CASES>(cases)...));
return res;
} else {
Switch(object, std::forward<OTHER_CASES>(other_cases)...);
return;
}
} else {
// That was the last case. No cases matched.
if constexpr (kHasReturnType) {
return {};
} else {
return;
}
}
detail::SwitchCases<T, void>(
object, &type, nullptr,
std::forward_as_tuple(std::forward<CASES>(cases)...));
}
}

View File

@ -124,16 +124,20 @@ constexpr auto Range() {
namespace detail {
/// @returns the tuple `t` swizzled by `INDICES`
template <class TUPLE, std::size_t... INDICES>
constexpr auto Swizzle(TUPLE&& t, std::index_sequence<INDICES...>) {
return std::make_tuple(std::get<INDICES>(std::forward<TUPLE>(t))...);
template <typename TUPLE, std::size_t... INDICES>
constexpr auto Swizzle(TUPLE&& t, std::index_sequence<INDICES...>)
-> std::tuple<
std::tuple_element_t<INDICES, std::remove_reference_t<TUPLE>>...> {
return {std::forward<
std::tuple_element_t<INDICES, std::remove_reference_t<TUPLE>>>(
std::get<INDICES>(std::forward<TUPLE>(t)))...};
}
/// @returns a nullptr of the tuple type `TUPLE` swizzled by `INDICES`.
/// @note: This function is intended to be used in a `decltype()` expression,
/// and returns a pointer-to-tuple as the tuple may hold non-constructable
/// types.
template <class TUPLE, std::size_t... INDICES>
template <typename TUPLE, std::size_t... INDICES>
constexpr auto* SwizzlePtrTy(std::index_sequence<INDICES...>) {
using Swizzled = std::tuple<std::tuple_element_t<INDICES, TUPLE>...>;
return static_cast<Swizzled*>(nullptr);

View File

@ -28,14 +28,14 @@ void F3(int, S, float) {}
TEST(ParamType, Function) {
F1({}); // Avoid unused method warning
F3(0, {}, 0); // Avoid unused method warning
static_assert(std::is_same_v<ParameterType<decltype(&F1), 0>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&F3), 0>, int>, "");
static_assert(std::is_same_v<ParameterType<decltype(&F3), 1>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&F3), 2>, float>, "");
static_assert(std::is_same_v<ReturnType<decltype(&F1)>, void>, "");
static_assert(std::is_same_v<ReturnType<decltype(&F3)>, void>, "");
static_assert(SignatureOfT<decltype(&F1)>::parameter_count == 1, "");
static_assert(SignatureOfT<decltype(&F3)>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<decltype(&F1), 0>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&F3), 0>, int>);
static_assert(std::is_same_v<ParameterType<decltype(&F3), 1>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&F3), 2>, float>);
static_assert(std::is_same_v<ReturnType<decltype(&F1)>, void>);
static_assert(std::is_same_v<ReturnType<decltype(&F3)>, void>);
static_assert(SignatureOfT<decltype(&F1)>::parameter_count == 1);
static_assert(SignatureOfT<decltype(&F3)>::parameter_count == 3);
}
TEST(ParamType, Method) {
@ -46,14 +46,14 @@ TEST(ParamType, Method) {
};
C().F1({}); // Avoid unused method warning
C().F3(0, {}, 0); // Avoid unused method warning
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>, "");
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1, "");
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>);
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1);
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3);
}
TEST(ParamType, ConstMethod) {
@ -64,14 +64,14 @@ TEST(ParamType, ConstMethod) {
};
C().F1({}); // Avoid unused method warning
C().F3(0, {}, 0); // Avoid unused method warning
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>, "");
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1, "");
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>);
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1);
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3);
}
TEST(ParamType, StaticMethod) {
@ -82,55 +82,55 @@ TEST(ParamType, StaticMethod) {
};
C::F1({}); // Avoid unused method warning
C::F3(0, {}, 0); // Avoid unused method warning
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>, "");
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>, "");
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1, "");
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<decltype(&C::F1), 0>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 0>, int>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 1>, S>);
static_assert(std::is_same_v<ParameterType<decltype(&C::F3), 2>, float>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F1)>, void>);
static_assert(std::is_same_v<ReturnType<decltype(&C::F3)>, void>);
static_assert(SignatureOfT<decltype(&C::F1)>::parameter_count == 1);
static_assert(SignatureOfT<decltype(&C::F3)>::parameter_count == 3);
}
TEST(ParamType, FunctionLike) {
using F1 = std::function<void(S)>;
using F3 = std::function<void(int, S, float)>;
static_assert(std::is_same_v<ParameterType<F1, 0>, S>, "");
static_assert(std::is_same_v<ParameterType<F3, 0>, int>, "");
static_assert(std::is_same_v<ParameterType<F3, 1>, S>, "");
static_assert(std::is_same_v<ParameterType<F3, 2>, float>, "");
static_assert(std::is_same_v<ReturnType<F1>, void>, "");
static_assert(std::is_same_v<ReturnType<F3>, void>, "");
static_assert(SignatureOfT<F1>::parameter_count == 1, "");
static_assert(SignatureOfT<F3>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<F1, 0>, S>);
static_assert(std::is_same_v<ParameterType<F3, 0>, int>);
static_assert(std::is_same_v<ParameterType<F3, 1>, S>);
static_assert(std::is_same_v<ParameterType<F3, 2>, float>);
static_assert(std::is_same_v<ReturnType<F1>, void>);
static_assert(std::is_same_v<ReturnType<F3>, void>);
static_assert(SignatureOfT<F1>::parameter_count == 1);
static_assert(SignatureOfT<F3>::parameter_count == 3);
}
TEST(ParamType, Lambda) {
auto l1 = [](S) {};
auto l3 = [](int, S, float) {};
static_assert(std::is_same_v<ParameterType<decltype(l1), 0>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(l3), 0>, int>, "");
static_assert(std::is_same_v<ParameterType<decltype(l3), 1>, S>, "");
static_assert(std::is_same_v<ParameterType<decltype(l3), 2>, float>, "");
static_assert(std::is_same_v<ReturnType<decltype(l1)>, void>, "");
static_assert(std::is_same_v<ReturnType<decltype(l3)>, void>, "");
static_assert(SignatureOfT<decltype(l1)>::parameter_count == 1, "");
static_assert(SignatureOfT<decltype(l3)>::parameter_count == 3, "");
static_assert(std::is_same_v<ParameterType<decltype(l1), 0>, S>);
static_assert(std::is_same_v<ParameterType<decltype(l3), 0>, int>);
static_assert(std::is_same_v<ParameterType<decltype(l3), 1>, S>);
static_assert(std::is_same_v<ParameterType<decltype(l3), 2>, float>);
static_assert(std::is_same_v<ReturnType<decltype(l1)>, void>);
static_assert(std::is_same_v<ReturnType<decltype(l3)>, void>);
static_assert(SignatureOfT<decltype(l1)>::parameter_count == 1);
static_assert(SignatureOfT<decltype(l3)>::parameter_count == 3);
}
TEST(Slice, Empty) {
auto sliced = Slice<0, 0>(std::make_tuple<>());
static_assert(std::tuple_size_v<decltype(sliced)> == 0, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 0);
}
TEST(Slice, SingleElementSliceEmpty) {
auto sliced = Slice<0, 0>(std::make_tuple<int>(1));
static_assert(std::tuple_size_v<decltype(sliced)> == 0, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 0);
}
TEST(Slice, SingleElementSliceFull) {
auto sliced = Slice<0, 1>(std::make_tuple<int>(1));
static_assert(std::tuple_size_v<decltype(sliced)> == 1, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 1);
static_assert(std::is_same_v<std::tuple_element_t<0, decltype(sliced)>, int>,
"");
EXPECT_EQ(std::get<0>(sliced), 1);
@ -138,18 +138,18 @@ TEST(Slice, SingleElementSliceFull) {
TEST(Slice, MixedTupleSliceEmpty) {
auto sliced = Slice<1, 0>(std::make_tuple<int, bool, float>(1, true, 2.0f));
static_assert(std::tuple_size_v<decltype(sliced)> == 0, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 0);
}
TEST(Slice, MixedTupleSliceFull) {
auto sliced = Slice<0, 3>(std::make_tuple<int, bool, float>(1, true, 2.0f));
static_assert(std::tuple_size_v<decltype(sliced)> == 3, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 3);
static_assert(std::is_same_v<std::tuple_element_t<0, decltype(sliced)>, int>,
"");
static_assert(std::is_same_v<std::tuple_element_t<1, decltype(sliced)>, bool>,
"");
static_assert(
std::is_same_v<std::tuple_element_t<2, decltype(sliced)>, float>, "");
std::is_same_v<std::tuple_element_t<2, decltype(sliced)>, float>);
EXPECT_EQ(std::get<0>(sliced), 1);
EXPECT_EQ(std::get<1>(sliced), true);
EXPECT_EQ(std::get<2>(sliced), 2.0f);
@ -157,7 +157,7 @@ TEST(Slice, MixedTupleSliceFull) {
TEST(Slice, MixedTupleSliceLowPart) {
auto sliced = Slice<0, 2>(std::make_tuple<int, bool, float>(1, true, 2.0f));
static_assert(std::tuple_size_v<decltype(sliced)> == 2, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 2);
static_assert(std::is_same_v<std::tuple_element_t<0, decltype(sliced)>, int>,
"");
static_assert(std::is_same_v<std::tuple_element_t<1, decltype(sliced)>, bool>,
@ -168,56 +168,67 @@ TEST(Slice, MixedTupleSliceLowPart) {
TEST(Slice, MixedTupleSliceHighPart) {
auto sliced = Slice<1, 2>(std::make_tuple<int, bool, float>(1, true, 2.0f));
static_assert(std::tuple_size_v<decltype(sliced)> == 2, "");
static_assert(std::tuple_size_v<decltype(sliced)> == 2);
static_assert(std::is_same_v<std::tuple_element_t<0, decltype(sliced)>, bool>,
"");
static_assert(
std::is_same_v<std::tuple_element_t<1, decltype(sliced)>, float>, "");
std::is_same_v<std::tuple_element_t<1, decltype(sliced)>, float>);
EXPECT_EQ(std::get<0>(sliced), true);
EXPECT_EQ(std::get<1>(sliced), 2.0f);
}
TEST(Slice, PreservesRValueRef) {
int i;
int& int_ref = i;
auto tuple = std::forward_as_tuple(std::move(int_ref));
static_assert(std::is_same_v<int&&, //
std::tuple_element_t<0, decltype(tuple)>>);
auto sliced = Slice<0, 1>(std::move(tuple));
static_assert(std::is_same_v<int&&, //
std::tuple_element_t<0, decltype(sliced)>>);
}
TEST(SliceTuple, Empty) {
using sliced = SliceTuple<0, 0, std::tuple<>>;
static_assert(std::tuple_size_v<sliced> == 0, "");
static_assert(std::tuple_size_v<sliced> == 0);
}
TEST(SliceTuple, SingleElementSliceEmpty) {
using sliced = SliceTuple<0, 0, std::tuple<int>>;
static_assert(std::tuple_size_v<sliced> == 0, "");
static_assert(std::tuple_size_v<sliced> == 0);
}
TEST(SliceTuple, SingleElementSliceFull) {
using sliced = SliceTuple<0, 1, std::tuple<int>>;
static_assert(std::tuple_size_v<sliced> == 1, "");
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>, "");
static_assert(std::tuple_size_v<sliced> == 1);
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>);
}
TEST(SliceTuple, MixedTupleSliceEmpty) {
using sliced = SliceTuple<1, 0, std::tuple<int, bool, float>>;
static_assert(std::tuple_size_v<sliced> == 0, "");
static_assert(std::tuple_size_v<sliced> == 0);
}
TEST(SliceTuple, MixedTupleSliceFull) {
using sliced = SliceTuple<0, 3, std::tuple<int, bool, float>>;
static_assert(std::tuple_size_v<sliced> == 3, "");
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>, "");
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, bool>, "");
static_assert(std::is_same_v<std::tuple_element_t<2, sliced>, float>, "");
static_assert(std::tuple_size_v<sliced> == 3);
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>);
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, bool>);
static_assert(std::is_same_v<std::tuple_element_t<2, sliced>, float>);
}
TEST(SliceTuple, MixedTupleSliceLowPart) {
using sliced = SliceTuple<0, 2, std::tuple<int, bool, float>>;
static_assert(std::tuple_size_v<sliced> == 2, "");
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>, "");
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, bool>, "");
static_assert(std::tuple_size_v<sliced> == 2);
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, int>);
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, bool>);
}
TEST(SliceTuple, MixedTupleSliceHighPart) {
using sliced = SliceTuple<1, 2, std::tuple<int, bool, float>>;
static_assert(std::tuple_size_v<sliced> == 2, "");
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, bool>, "");
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, float>, "");
static_assert(std::tuple_size_v<sliced> == 2);
static_assert(std::is_same_v<std::tuple_element_t<0, sliced>, bool>);
static_assert(std::is_same_v<std::tuple_element_t<1, sliced>, float>);
}
} // namespace traits