diff options
Diffstat (limited to 'absl/meta')
| -rw-r--r-- | absl/meta/CMakeLists.txt | 2 | ||||
| -rw-r--r-- | absl/meta/type_traits.h | 109 | ||||
| -rw-r--r-- | absl/meta/type_traits_test.cc | 191 |
3 files changed, 299 insertions, 3 deletions
diff --git a/absl/meta/CMakeLists.txt b/absl/meta/CMakeLists.txt index f866e54e9271..672ead2fd0a5 100644 --- a/absl/meta/CMakeLists.txt +++ b/absl/meta/CMakeLists.txt @@ -42,6 +42,8 @@ absl_cc_test( absl_cc_library( NAME meta + COPTS + ${ABSL_DEFAULT_COPTS} DEPS absl::type_traits PUBLIC diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index a8068e315ed3..c08e3754689b 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -43,8 +43,39 @@ namespace absl { +// Defined and documented later on in this file. +template <typename T> +struct is_trivially_move_assignable; + namespace type_traits_internal { +// Silence MSVC warnings about the destructor being defined as deleted. +#if defined(_MSC_VER) && !defined(__GNUC__) +#pragma warning(push) +#pragma warning(disable : 4624) +#endif // defined(_MSC_VER) && !defined(__GNUC__) + +template <class T> +union SingleMemberUnion { + T t; +}; + +// Restore the state of the destructor warning that was silenced above. +#if defined(_MSC_VER) && !defined(__GNUC__) +#pragma warning(pop) +#endif // defined(_MSC_VER) && !defined(__GNUC__) + +template <class T> +struct IsTriviallyMoveAssignableReference : std::false_type {}; + +template <class T> +struct IsTriviallyMoveAssignableReference<T&> + : absl::is_trivially_move_assignable<T>::type {}; + +template <class T> +struct IsTriviallyMoveAssignableReference<T&&> + : absl::is_trivially_move_assignable<T>::type {}; + template <typename... Ts> struct VoidTImpl { using type = void; @@ -275,6 +306,40 @@ struct is_trivially_default_constructible #endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE }; +// is_trivially_move_constructible() +// +// Determines whether the passed type `T` is trivially move constructible. +// +// This metafunction is designed to be a drop-in replacement for the C++11 +// `std::is_trivially_move_constructible()` metafunction for platforms that have +// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do +// fully support C++11, we check whether this yields the same result as the std +// implementation. +// +// NOTE: `T obj(declval<T>());` needs to be well-formed and not call any +// nontrivial operation. Nontrivially destructible types will cause the +// expression to be nontrivial. +template <typename T> +struct is_trivially_move_constructible + : std::conditional< + std::is_object<T>::value && !std::is_array<T>::value, + std::is_move_constructible< + type_traits_internal::SingleMemberUnion<T>>, + std::is_reference<T>>::type::type { +#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE + private: + static constexpr bool compliant = + std::is_trivially_move_constructible<T>::value == + is_trivially_move_constructible::value; + static_assert(compliant || std::is_trivially_move_constructible<T>::value, + "Not compliant with std::is_trivially_move_constructible; " + "Standard: false, Implementation: true"); + static_assert(compliant || !std::is_trivially_move_constructible<T>::value, + "Not compliant with std::is_trivially_move_constructible; " + "Standard: true, Implementation: false"); +#endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE +}; + // is_trivially_copy_constructible() // // Determines whether the passed type `T` is trivially copy constructible. @@ -290,9 +355,11 @@ struct is_trivially_default_constructible // expression to be nontrivial. template <typename T> struct is_trivially_copy_constructible - : std::integral_constant<bool, __has_trivial_copy(T) && - std::is_copy_constructible<T>::value && - is_trivially_destructible<T>::value> { + : std::conditional< + std::is_object<T>::value && !std::is_array<T>::value, + std::is_copy_constructible< + type_traits_internal::SingleMemberUnion<T>>, + std::is_lvalue_reference<T>>::type::type { #ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE private: static constexpr bool compliant = @@ -307,6 +374,42 @@ struct is_trivially_copy_constructible #endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE }; +// is_trivially_move_assignable() +// +// Determines whether the passed type `T` is trivially move assignable. +// +// This metafunction is designed to be a drop-in replacement for the C++11 +// `std::is_trivially_move_assignable()` metafunction for platforms that have +// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do +// fully support C++11, we check whether this yields the same result as the std +// implementation. +// +// NOTE: `is_assignable<T, U>::value` is `true` if the expression +// `declval<T>() = declval<U>()` is well-formed when treated as an unevaluated +// operand. `is_trivially_assignable<T, U>` requires the assignment to call no +// operation that is not trivial. `is_trivially_copy_assignable<T>` is simply +// `is_trivially_assignable<T&, T>`. +template <typename T> +struct is_trivially_move_assignable + : std::conditional< + std::is_object<T>::value && !std::is_array<T>::value, + std::is_move_assignable<type_traits_internal::SingleMemberUnion<T>>, + type_traits_internal::IsTriviallyMoveAssignableReference<T>>::type:: + type { +#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE + private: + static constexpr bool compliant = + std::is_trivially_move_assignable<T>::value == + is_trivially_move_assignable::value; + static_assert(compliant || std::is_trivially_move_assignable<T>::value, + "Not compliant with std::is_trivially_move_assignable; " + "Standard: false, Implementation: true"); + static_assert(compliant || !std::is_trivially_move_assignable<T>::value, + "Not compliant with std::is_trivially_move_assignable; " + "Standard: true, Implementation: false"); +#endif // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE +}; + // is_trivially_copy_assignable() // // Determines whether the passed type `T` is trivially copy assignable. diff --git a/absl/meta/type_traits_test.cc b/absl/meta/type_traits_test.cc index d3ead6d05158..82b1be51065e 100644 --- a/absl/meta/type_traits_test.cc +++ b/absl/meta/type_traits_test.cc @@ -214,6 +214,29 @@ class DeletedDefaultCtor { int n_; }; +class TrivialMoveCtor { + public: + explicit TrivialMoveCtor(int n) : n_(n) {} + TrivialMoveCtor(TrivialMoveCtor&&) = default; + TrivialMoveCtor& operator=(const TrivialMoveCtor& t) { + n_ = t.n_; + return *this; + } + + private: + int n_; +}; + +class NontrivialMoveCtor { + public: + explicit NontrivialMoveCtor(int n) : n_(n) {} + NontrivialMoveCtor(NontrivialMoveCtor&& t) noexcept : n_(t.n_) {} + NontrivialMoveCtor& operator=(const NontrivialMoveCtor&) = default; + + private: + int n_; +}; + class TrivialCopyCtor { public: explicit TrivialCopyCtor(int n) : n_(n) {} @@ -247,6 +270,29 @@ class DeletedCopyCtor { int n_; }; +class TrivialMoveAssign { + public: + explicit TrivialMoveAssign(int n) : n_(n) {} + TrivialMoveAssign(const TrivialMoveAssign& t) : n_(t.n_) {} + TrivialMoveAssign& operator=(TrivialMoveAssign&&) = default; + ~TrivialMoveAssign() {} // can have nontrivial destructor + private: + int n_; +}; + +class NontrivialMoveAssign { + public: + explicit NontrivialMoveAssign(int n) : n_(n) {} + NontrivialMoveAssign(const NontrivialMoveAssign&) = default; + NontrivialMoveAssign& operator=(NontrivialMoveAssign&& t) noexcept { + n_ = t.n_; + return *this; + } + + private: + int n_; +}; + class TrivialCopyAssign { public: explicit TrivialCopyAssign(int n) : n_(n) {} @@ -484,6 +530,79 @@ TEST(TypeTraitsTest, TestTrivialDefaultCtor) { #endif } +TEST(TypeTraitsTest, TestTrivialMoveCtor) { + // Verify that arithmetic types and pointers have trivial move + // constructors. + EXPECT_TRUE(absl::is_trivially_move_constructible<bool>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<char>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<unsigned char>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<signed char>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<wchar_t>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<int>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<unsigned int>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<int16_t>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<uint16_t>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<int64_t>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<uint64_t>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<float>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<double>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<long double>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<std::string*>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial*>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<const std::string*>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<const Trivial*>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<std::string**>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial**>::value); + + // Reference types + EXPECT_TRUE(absl::is_trivially_move_constructible<int&>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<int&&>::value); + + // types with compiler generated move ctors + EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial>::value); + EXPECT_TRUE(absl::is_trivially_move_constructible<TrivialMoveCtor>::value); + + // Verify that types without them (i.e. nontrivial or deleted) are not. + EXPECT_FALSE( + absl::is_trivially_move_constructible<NontrivialCopyCtor>::value); + EXPECT_FALSE(absl::is_trivially_move_constructible<DeletedCopyCtor>::value); + EXPECT_FALSE( + absl::is_trivially_move_constructible<NonCopyableOrMovable>::value); + +#ifdef ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE + // type with nontrivial destructor are nontrivial move construbtible + EXPECT_FALSE( + absl::is_trivially_move_constructible<NontrivialDestructor>::value); +#endif + + // types with vtables + EXPECT_FALSE(absl::is_trivially_move_constructible<Base>::value); + + // Verify that simple_pair of such types is trivially move constructible + EXPECT_TRUE( + (absl::is_trivially_move_constructible<simple_pair<int, char*>>::value)); + EXPECT_TRUE(( + absl::is_trivially_move_constructible<simple_pair<int, Trivial>>::value)); + EXPECT_TRUE((absl::is_trivially_move_constructible< + simple_pair<int, TrivialMoveCtor>>::value)); + + // Verify that types without trivial move constructors are + // correctly marked as such. + EXPECT_FALSE(absl::is_trivially_move_constructible<std::string>::value); + EXPECT_FALSE(absl::is_trivially_move_constructible<std::vector<int>>::value); + + // Verify that simple_pairs of types without trivial move constructors + // are not marked as trivial. + EXPECT_FALSE((absl::is_trivially_move_constructible< + simple_pair<int, std::string>>::value)); + EXPECT_FALSE((absl::is_trivially_move_constructible< + simple_pair<std::string, int>>::value)); + + // Verify that arrays are not + using int10 = int[10]; + EXPECT_FALSE(absl::is_trivially_move_constructible<int10>::value); +} + TEST(TypeTraitsTest, TestTrivialCopyCtor) { // Verify that arithmetic types and pointers have trivial copy // constructors. @@ -508,6 +627,10 @@ TEST(TypeTraitsTest, TestTrivialCopyCtor) { EXPECT_TRUE(absl::is_trivially_copy_constructible<std::string**>::value); EXPECT_TRUE(absl::is_trivially_copy_constructible<Trivial**>::value); + // Reference types + EXPECT_TRUE(absl::is_trivially_copy_constructible<int&>::value); + EXPECT_FALSE(absl::is_trivially_copy_constructible<int&&>::value); + // types with compiler generated copy ctors EXPECT_TRUE(absl::is_trivially_copy_constructible<Trivial>::value); EXPECT_TRUE(absl::is_trivially_copy_constructible<TrivialCopyCtor>::value); @@ -555,6 +678,74 @@ TEST(TypeTraitsTest, TestTrivialCopyCtor) { EXPECT_FALSE(absl::is_trivially_copy_constructible<int10>::value); } +TEST(TypeTraitsTest, TestTrivialMoveAssign) { + // Verify that arithmetic types and pointers have trivial move + // assignment operators. + EXPECT_TRUE(absl::is_trivially_move_assignable<bool>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<char>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<unsigned char>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<signed char>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<wchar_t>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<int>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<unsigned int>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<int16_t>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<uint16_t>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<int64_t>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<uint64_t>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<float>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<double>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<long double>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<std::string*>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial*>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<const std::string*>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<const Trivial*>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<std::string**>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial**>::value); + + // const qualified types are not assignable + EXPECT_FALSE(absl::is_trivially_move_assignable<const int>::value); + + // types with compiler generated move assignment + EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<TrivialMoveAssign>::value); + + // Verify that types without them (i.e. nontrivial or deleted) are not. + EXPECT_FALSE(absl::is_trivially_move_assignable<NontrivialCopyAssign>::value); + EXPECT_FALSE(absl::is_trivially_move_assignable<DeletedCopyAssign>::value); + EXPECT_FALSE(absl::is_trivially_move_assignable<NonCopyableOrMovable>::value); + + // types with vtables + EXPECT_FALSE(absl::is_trivially_move_assignable<Base>::value); + + // Verify that simple_pair is trivially assignable + EXPECT_TRUE( + (absl::is_trivially_move_assignable<simple_pair<int, char*>>::value)); + EXPECT_TRUE( + (absl::is_trivially_move_assignable<simple_pair<int, Trivial>>::value)); + EXPECT_TRUE((absl::is_trivially_move_assignable< + simple_pair<int, TrivialMoveAssign>>::value)); + + // Verify that types not trivially move assignable are + // correctly marked as such. + EXPECT_FALSE(absl::is_trivially_move_assignable<std::string>::value); + EXPECT_FALSE(absl::is_trivially_move_assignable<std::vector<int>>::value); + + // Verify that simple_pairs of types not trivially move assignable + // are not marked as trivial. + EXPECT_FALSE((absl::is_trivially_move_assignable< + simple_pair<int, std::string>>::value)); + EXPECT_FALSE((absl::is_trivially_move_assignable< + simple_pair<std::string, int>>::value)); + + // Verify that arrays are not trivially move assignable + using int10 = int[10]; + EXPECT_FALSE(absl::is_trivially_move_assignable<int10>::value); + + // Verify that references are handled correctly + EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial&&>::value); + EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial&>::value); +} + TEST(TypeTraitsTest, TestTrivialCopyAssign) { // Verify that arithmetic types and pointers have trivial copy // assignment operators. |