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-rw-r--r--absl/hash/hash_test.cc22
-rw-r--r--absl/hash/internal/hash.h161
2 files changed, 72 insertions, 111 deletions
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index d9ebd30f..a2430e7a 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -165,9 +165,6 @@ TEST(HashValueTest, PointerAlignment) {
}
}
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
TEST(HashValueTest, PairAndTuple) {
EXPECT_TRUE((is_hashable<std::pair<int, int>>::value));
EXPECT_TRUE((is_hashable<std::pair<const int&, const int&>>::value));
@@ -196,7 +193,6 @@ TEST(HashValueTest, PairAndTuple) {
std::forward_as_tuple(42, 0, 0), std::forward_as_tuple(3, 9, 9),
std::forward_as_tuple(0, 0, -42))));
}
-#endif // !defined(_MSC_VER)
TEST(HashValueTest, CombineContiguousWorks) {
std::vector<std::tuple<int>> v1 = {std::make_tuple(1), std::make_tuple(3)};
@@ -304,16 +300,12 @@ TEST(HashValueTest, Strings) {
SpyHash(absl::string_view("ABC")));
}
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
TEST(HashValueTest, StdArray) {
EXPECT_TRUE((is_hashable<std::array<int, 3>>::value));
EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(
std::make_tuple(std::array<int, 3>{}, std::array<int, 3>{{0, 23, 42}})));
}
-#endif // !defined(_MSC_VER)
TEST(HashValueTest, StdBitset) {
EXPECT_TRUE((is_hashable<std::bitset<257>>::value));
@@ -414,9 +406,6 @@ TEST(HashValueTest, Variant) {
#endif
}
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
TEST(HashValueTest, Maps) {
EXPECT_TRUE((is_hashable<std::map<int, std::string>>::value));
@@ -433,7 +422,6 @@ TEST(HashValueTest, Maps) {
MM{{0, "foo"}, {42, "bar"}}, MM{{1, "foo"}, {42, "bar"}},
MM{{1, "foo"}, {1, "foo"}, {43, "bar"}}, MM{{1, "foo"}, {43, "baz"}})));
}
-#endif // !defined(_MSC_VER)
template <typename T, typename = void>
struct IsHashCallble : std::false_type {};
@@ -511,8 +499,16 @@ struct CombineVariadic {
Int(4));
}
};
+enum class InvokeTag {
+ kUniquelyRepresented,
+ kHashValue,
+#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
+ kLegacyHash,
+#endif // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
+ kStdHash,
+ kNone
+};
-using InvokeTag = absl::hash_internal::InvokeHashTag;
template <InvokeTag T>
using InvokeTagConstant = std::integral_constant<InvokeTag, T>;
diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index 2a45bc84..9ab98901 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -535,20 +535,6 @@ hash_range_or_bytes(H hash_state, const T* data, size_t size) {
return hash_state;
}
-// InvokeHashTag
-//
-// InvokeHash(H, const T&) invokes the appropriate hash implementation for a
-// hasher of type `H` and a value of type `T`. If `T` is not hashable, there
-// will be no matching overload of InvokeHash().
-// Note: Some platforms (eg MSVC) do not support the detect idiom on
-// std::hash. In those platforms the last fallback will be std::hash and
-// InvokeHash() will always have a valid overload even if std::hash<T> is not
-// valid.
-//
-// We try the following options in order:
-// * If is_uniquely_represented, hash bytes directly.
-// * ADL AbslHashValue(H, const T&) call.
-// * std::hash<T>
#if defined(ABSL_INTERNAL_LEGACY_HASH_NAMESPACE) && \
ABSL_META_INTERNAL_STD_HASH_SFINAE_FRIENDLY_
#define ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_ 1
@@ -556,23 +542,15 @@ hash_range_or_bytes(H hash_state, const T* data, size_t size) {
#define ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_ 0
#endif
-enum class InvokeHashTag {
- kUniquelyRepresented,
- kHashValue,
-#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
- kLegacyHash,
-#endif // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
- kStdHash,
- kNone
-};
-
// HashSelect
//
// Type trait to select the appropriate hash implementation to use.
-// HashSelect<T>::value is an instance of InvokeHashTag that indicates the best
-// available hashing mechanism.
-// See `Note` above about MSVC.
-template <typename T>
+// HashSelect::type<T> will give the proper hash implementation, to be invoked
+// as:
+// HashSelect::type<T>::Invoke(state, value)
+// Also, HashSelect::type<T>::value is a boolean equal to `true` if there is a
+// valid `Invoke` function. Types that are not hashable will have a ::value of
+// `false`.
struct HashSelect {
private:
struct State : HashStateBase<State> {
@@ -581,89 +559,75 @@ struct HashSelect {
using State::HashStateBase::combine_contiguous;
};
- // `Probe<V, Tag>::value` evaluates to `V<T>::value` if it is a valid
- // expression, and `false` otherwise.
- // `Probe<V, Tag>::tag` always evaluates to `Tag`.
- template <template <typename> class V, InvokeHashTag Tag>
- struct Probe {
- private:
- template <typename U, typename std::enable_if<V<U>::value, int>::type = 0>
- static std::true_type Test(int);
- template <typename U>
- static std::false_type Test(char);
-
- public:
- static constexpr InvokeHashTag kTag = Tag;
- static constexpr bool value = decltype(
- Test<absl::remove_const_t<absl::remove_reference_t<T>>>(0))::value;
+ struct UniquelyRepresentedProbe {
+ template <typename H, typename T>
+ static auto Invoke(H state, const T& value)
+ -> absl::enable_if_t<is_uniquely_represented<T>::value, H> {
+ return hash_internal::hash_bytes(std::move(state), value);
+ }
};
- template <typename U>
- using ProbeUniquelyRepresented = is_uniquely_represented<U>;
-
- template <typename U>
- using ProbeHashValue =
- std::is_same<State, decltype(AbslHashValue(std::declval<State>(),
- std::declval<const U&>()))>;
+ struct HashValueProbe {
+ template <typename H, typename T>
+ static auto Invoke(H state, const T& value) -> absl::enable_if_t<
+ std::is_same<H,
+ decltype(AbslHashValue(std::move(state), value))>::value,
+ H> {
+ return AbslHashValue(std::move(state), value);
+ }
+ };
+ struct LegacyHashProbe {
#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
- template <typename U>
- using ProbeLegacyHash =
- std::is_convertible<decltype(ABSL_INTERNAL_LEGACY_HASH_NAMESPACE::hash<
- U>()(std::declval<const U&>())),
- size_t>;
+ template <typename H, typename T>
+ static auto Invoke(H state, const T& value) -> absl::enable_if_t<
+ std::is_convertible<
+ decltype(ABSL_INTERNAL_LEGACY_HASH_NAMESPACE::hash<T>()(value)),
+ size_t>::value,
+ H> {
+ return hash_internal::hash_bytes(
+ std::move(state),
+ ABSL_INTERNAL_LEGACY_HASH_NAMESPACE::hash<T>{}(value));
+ }
#endif // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
+ };
- template <typename U>
- using ProbeStdHash = absl::type_traits_internal::IsHashable<U>;
+ struct StdHashProbe {
+ template <typename H, typename T>
+ static auto Invoke(H state, const T& value)
+ -> absl::enable_if_t<type_traits_internal::IsHashable<T>::value, H> {
+ return hash_internal::hash_bytes(std::move(state), std::hash<T>{}(value));
+ }
+ };
- template <typename U>
- using ProbeNone = std::true_type;
+ template <typename Hash, typename T>
+ struct Probe : Hash {
+ private:
+ template <typename H, typename = decltype(H::Invoke(
+ std::declval<State>(), std::declval<const T&>()))>
+ static std::true_type Test(int);
+ template <typename U>
+ static std::false_type Test(char);
+
+ public:
+ static constexpr bool value = decltype(Test<Hash>(0))::value;
+ };
public:
// Probe each implementation in order.
// disjunction provides short circuting wrt instantiation.
- static constexpr InvokeHashTag value = absl::disjunction<
- Probe<ProbeUniquelyRepresented, InvokeHashTag::kUniquelyRepresented>,
- Probe<ProbeHashValue, InvokeHashTag::kHashValue>,
-#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
- Probe<ProbeLegacyHash, InvokeHashTag::kLegacyHash>,
-#endif // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
- Probe<ProbeStdHash, InvokeHashTag::kStdHash>,
- Probe<ProbeNone, InvokeHashTag::kNone>>::kTag;
+ template <typename T>
+ using Apply = absl::disjunction< //
+ Probe<UniquelyRepresentedProbe, T>, //
+ Probe<HashValueProbe, T>, //
+ Probe<LegacyHashProbe, T>, //
+ Probe<StdHashProbe, T>, //
+ std::false_type>;
};
template <typename T>
-struct is_hashable : std::integral_constant<bool, HashSelect<T>::value !=
- InvokeHashTag::kNone> {};
-
-template <typename H, typename T>
-absl::enable_if_t<HashSelect<T>::value == InvokeHashTag::kUniquelyRepresented,
- H>
-InvokeHash(H state, const T& value) {
- return hash_internal::hash_bytes(std::move(state), value);
-}
-
-template <typename H, typename T>
-absl::enable_if_t<HashSelect<T>::value == InvokeHashTag::kHashValue, H>
-InvokeHash(H state, const T& value) {
- return AbslHashValue(std::move(state), value);
-}
-
-#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
-template <typename H, typename T>
-absl::enable_if_t<HashSelect<T>::value == InvokeHashTag::kLegacyHash, H>
-InvokeHash(H state, const T& value) {
- return hash_internal::hash_bytes(
- std::move(state), ABSL_INTERNAL_LEGACY_HASH_NAMESPACE::hash<T>{}(value));
-}
-#endif // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
-
-template <typename H, typename T>
-absl::enable_if_t<HashSelect<T>::value == InvokeHashTag::kStdHash, H>
-InvokeHash(H state, const T& value) {
- return hash_internal::hash_bytes(std::move(state), std::hash<T>{}(value));
-}
+struct is_hashable
+ : std::integral_constant<bool, HashSelect::template Apply<T>::value> {};
// CityHashState
class CityHashState : public HashStateBase<CityHashState> {
@@ -873,7 +837,8 @@ struct Hash
template <typename H>
template <typename T, typename... Ts>
H HashStateBase<H>::combine(H state, const T& value, const Ts&... values) {
- return H::combine(hash_internal::InvokeHash(std::move(state), value),
+ return H::combine(hash_internal::HashSelect::template Apply<T>::Invoke(
+ std::move(state), value),
values...);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-23 09:39:55 +0000