Merge "Add expected<void,E>" (bb1b83e3) · Commits · e / os / android_system_core

base/expected_test.cpp

+149 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@ typedef expected<int, int> exp_int;
		typedef expected<double, double> exp_double;
		typedef expected<std::string, std::string> exp_string;
		typedef expected<std::pair<std::string, int>, int> exp_pair;
		typedef expected<void, int> exp_void;

		struct T {
		int a;
		@@ -59,6 +60,9 @@ TEST(Expected, testDefaultConstructible) {
		exp_complex e2;
		EXPECT_TRUE(e2.has_value());
		EXPECT_EQ(T(0,0), e2.value());

		exp_void e3;
		EXPECT_TRUE(e3.has_value());
		}

		TEST(Expected, testCopyConstructible) {
		@@ -69,6 +73,11 @@ TEST(Expected, testCopyConstructible) {
		EXPECT_TRUE(e2.has_value());
		EXPECT_EQ(0, e.value());
		EXPECT_EQ(0, e2.value());

		exp_void e3;
		exp_void e4 = e3;
		EXPECT_TRUE(e3.has_value());
		EXPECT_TRUE(e4.has_value());
		}

		TEST(Expected, testMoveConstructible) {
		@@ -87,6 +96,11 @@ TEST(Expected, testMoveConstructible) {
		EXPECT_TRUE(e4.has_value());
		EXPECT_EQ("", e3.value()); // e3 is moved
		EXPECT_EQ("hello", e4.value());

		exp_void e5;
		exp_void e6 = std::move(e5);
		EXPECT_TRUE(e5.has_value());
		EXPECT_TRUE(e6.has_value());
		}

		TEST(Expected, testCopyConstructibleFromConvertibleType) {
		@@ -114,11 +128,13 @@ TEST(Expected, testConstructibleFromValue) {
		exp_double e2 = 5.5f;
		exp_string e3 = std::string("hello");
		exp_complex e4 = T(10, 20);
		exp_void e5 = {};

		EXPECT_TRUE(e.has_value());
		EXPECT_TRUE(e2.has_value());
		EXPECT_TRUE(e3.has_value());
		EXPECT_TRUE(e4.has_value());
		EXPECT_TRUE(e5.has_value());
		EXPECT_EQ(3, e.value());
		EXPECT_EQ(5.5f, e2.value());
		EXPECT_EQ("hello", e3.value());
		@@ -154,25 +170,33 @@ TEST(Expected, testConstructibleFromUnexpected) {
		exp_string::unexpected_type unexp3 = unexpected(std::string("error"));
		exp_string e3 = unexp3;

		exp_void::unexpected_type unexp4 = unexpected(10);
		exp_void e4 = unexp4;

		EXPECT_FALSE(e.has_value());
		EXPECT_FALSE(e2.has_value());
		EXPECT_FALSE(e3.has_value());
		EXPECT_FALSE(e4.has_value());
		EXPECT_EQ(10, e.error());
		EXPECT_EQ(10.5f, e2.error());
		EXPECT_EQ("error", e3.error());
		EXPECT_EQ(10, e4.error());
		}

		TEST(Expected, testMoveConstructibleFromUnexpected) {
		exp_int e = unexpected(10);
		exp_double e2 = unexpected(10.5f);
		exp_string e3 = unexpected(std::string("error"));
		exp_void e4 = unexpected(10);

		EXPECT_FALSE(e.has_value());
		EXPECT_FALSE(e2.has_value());
		EXPECT_FALSE(e3.has_value());
		EXPECT_FALSE(e4.has_value());
		EXPECT_EQ(10, e.error());
		EXPECT_EQ(10.5f, e2.error());
		EXPECT_EQ("error", e3.error());
		EXPECT_EQ(10, e4.error());
		}

		TEST(Expected, testConstructibleByForwarding) {
		@@ -188,6 +212,9 @@ TEST(Expected, testConstructibleByForwarding) {
		EXPECT_TRUE(e3.has_value());
		EXPECT_EQ("hello",e3->first);
		EXPECT_EQ(30,e3->second);

		exp_void e4({});
		EXPECT_TRUE(e4.has_value());
		}

		TEST(Expected, testDestructible) {
		@@ -217,6 +244,14 @@ TEST(Expected, testAssignable) {

		EXPECT_EQ(20, e3.value());
		EXPECT_EQ(20, e4.value());

		exp_void e5 = unexpected(10);
		ASSERT_FALSE(e5.has_value());
		exp_void e6;
		e5 = e6;

		EXPECT_TRUE(e5.has_value());
		EXPECT_TRUE(e6.has_value());
		}

		TEST(Expected, testAssignableFromValue) {
		@@ -231,6 +266,11 @@ TEST(Expected, testAssignableFromValue) {
		exp_string e3 = "hello";
		e3 = "world";
		EXPECT_EQ("world", e3.value());

		exp_void e4 = unexpected(10);
		ASSERT_FALSE(e4.has_value());
		e4 = {};
		EXPECT_TRUE(e4.has_value());
		}

		TEST(Expected, testAssignableFromUnexpected) {
		@@ -248,6 +288,11 @@ TEST(Expected, testAssignableFromUnexpected) {
		e3 = unexpected("world");
		EXPECT_FALSE(e3.has_value());
		EXPECT_EQ("world", e3.error());

		exp_void e4 = {};
		e4 = unexpected(10);
		EXPECT_FALSE(e4.has_value());
		EXPECT_EQ(10, e4.error());
		}

		TEST(Expected, testAssignableFromMovedValue) {
		@@ -285,6 +330,11 @@ TEST(Expected, testEmplace) {
		EXPECT_EQ(10.5f, t.b);
		EXPECT_EQ(3, exp.value().a);
		EXPECT_EQ(10.5, exp.value().b);

		exp_void e = unexpected(10);
		ASSERT_FALSE(e.has_value());
		e.emplace();
		EXPECT_TRUE(e.has_value());
		}

		TEST(Expected, testSwapExpectedExpected) {
		@@ -296,6 +346,13 @@ TEST(Expected, testSwapExpectedExpected) {
		EXPECT_TRUE(e2.has_value());
		EXPECT_EQ(20, e.value());
		EXPECT_EQ(10, e2.value());

		exp_void e3;
		exp_void e4;
		e3.swap(e4);

		EXPECT_TRUE(e3.has_value());
		EXPECT_TRUE(e4.has_value());
		}

		TEST(Expected, testSwapUnexpectedUnexpected) {
		@@ -306,6 +363,14 @@ TEST(Expected, testSwapUnexpectedUnexpected) {
		EXPECT_FALSE(e2.has_value());
		EXPECT_EQ(20, e.error());
		EXPECT_EQ(10, e2.error());

		exp_void e3 = unexpected(10);
		exp_void e4 = unexpected(20);
		e3.swap(e4);
		EXPECT_FALSE(e3.has_value());
		EXPECT_FALSE(e4.has_value());
		EXPECT_EQ(20, e3.error());
		EXPECT_EQ(10, e4.error());
		}

		TEST(Expected, testSwapExpectedUnepected) {
		@@ -316,6 +381,13 @@ TEST(Expected, testSwapExpectedUnepected) {
		EXPECT_TRUE(e2.has_value());
		EXPECT_EQ(30, e.error());
		EXPECT_EQ(10, e2.value());

		exp_void e3;
		exp_void e4 = unexpected(10);
		e3.swap(e4);
		EXPECT_FALSE(e3.has_value());
		EXPECT_TRUE(e4.has_value());
		EXPECT_EQ(10, e3.error());
		}

		TEST(Expected, testDereference) {
		@@ -361,6 +433,13 @@ TEST(Expected, testSameValues) {
		EXPECT_TRUE(e2 == e);
		EXPECT_FALSE(e != e2);
		EXPECT_FALSE(e2 != e);

		exp_void e3;
		exp_void e4;
		EXPECT_TRUE(e3 == e4);
		EXPECT_TRUE(e4 == e3);
		EXPECT_FALSE(e3 != e4);
		EXPECT_FALSE(e4 != e3);
		}

		TEST(Expected, testDifferentValues) {
		@@ -379,6 +458,13 @@ TEST(Expected, testValueWithError) {
		EXPECT_FALSE(e2 == e);
		EXPECT_TRUE(e != e2);
		EXPECT_TRUE(e2 != e);

		exp_void e3;
		exp_void e4 = unexpected(10);
		EXPECT_FALSE(e3 == e4);
		EXPECT_FALSE(e4 == e3);
		EXPECT_TRUE(e3 != e4);
		EXPECT_TRUE(e4 != e3);
		}

		TEST(Expected, testSameErrors) {
		@@ -388,6 +474,13 @@ TEST(Expected, testSameErrors) {
		EXPECT_TRUE(e2 == e);
		EXPECT_FALSE(e != e2);
		EXPECT_FALSE(e2 != e);

		exp_void e3 = unexpected(10);
		exp_void e4 = unexpected(10);
		EXPECT_TRUE(e3 == e4);
		EXPECT_TRUE(e4 == e3);
		EXPECT_FALSE(e3 != e4);
		EXPECT_FALSE(e4 != e3);
		}

		TEST(Expected, testDifferentErrors) {
		@@ -397,6 +490,13 @@ TEST(Expected, testDifferentErrors) {
		EXPECT_FALSE(e2 == e);
		EXPECT_TRUE(e != e2);
		EXPECT_TRUE(e2 != e);

		exp_void e3 = unexpected(10);
		exp_void e4 = unexpected(20);
		EXPECT_FALSE(e3 == e4);
		EXPECT_FALSE(e4 == e3);
		EXPECT_TRUE(e3 != e4);
		EXPECT_TRUE(e4 != e3);
		}

		TEST(Expected, testCompareWithSameValue) {
		@@ -424,6 +524,13 @@ TEST(Expected, testCompareWithSameError) {
		EXPECT_TRUE(error == e);
		EXPECT_FALSE(e != error);
		EXPECT_FALSE(error != e);

		exp_void e2 = unexpected(10);
		exp_void::unexpected_type error2 = 10;
		EXPECT_TRUE(e2 == error2);
		EXPECT_TRUE(error2 == e2);
		EXPECT_FALSE(e2 != error2);
		EXPECT_FALSE(error2 != e2);
		}

		TEST(Expected, testCompareWithDifferentError) {
		@@ -433,6 +540,32 @@ TEST(Expected, testCompareWithDifferentError) {
		EXPECT_FALSE(error == e);
		EXPECT_TRUE(e != error);
		EXPECT_TRUE(error != e);

		exp_void e2 = unexpected(10);
		exp_void::unexpected_type error2 = 20;
		EXPECT_FALSE(e2 == error2);
		EXPECT_FALSE(error2 == e2);
		EXPECT_TRUE(e2 != error2);
		EXPECT_TRUE(error2 != e2);
		}

		TEST(Expected, testCompareDifferentType) {
		expected<int,int> e = 10;
		expected<int32_t, int> e2 = 10;
		EXPECT_TRUE(e == e2);
		e2 = 20;
		EXPECT_FALSE(e == e2);

		expected<std::string_view,int> e3 = "hello";
		expected<std::string,int> e4 = "hello";
		EXPECT_TRUE(e3 == e4);
		e4 = "world";
		EXPECT_FALSE(e3 == e4);

		expected<void,int> e5;
		expected<int,int> e6 = 10;
		EXPECT_FALSE(e5 == e6);
		EXPECT_FALSE(e6 == e5);
		}

		TEST(Expected, testDivideExample) {
		@@ -478,6 +611,22 @@ TEST(Expected, testPair) {
		EXPECT_EQ("yes", r->first);
		}

		TEST(Expected, testVoid) {
		auto test = [](bool ok) -> exp_void {
		if (ok) {
		return {};
		} else {
		return unexpected(10);
		}
		};

		auto r = test(true);
		EXPECT_TRUE(r);
		r = test(false);
		EXPECT_FALSE(r);
		EXPECT_EQ(10, r.error());
		}

		// copied from result_test.cpp
		struct ConstructorTracker {
		static size_t constructor_called;

base/include/android-base/expected.h

+189 −7

Original line number	Diff line number	Diff line
		@@ -412,13 +412,7 @@ constexpr bool operator==(const expected<T1, E1>& x, const expected<T2, E2>& y)

		template<class T1, class E1, class T2, class E2>
		constexpr bool operator!=(const expected<T1, E1>& x, const expected<T2, E2>& y) {
		if (x.has_value() != y.has_value()) {
		return true;
		} else if (!x.has_value()) {
		return x.error() != y.error();
		} else {
		return x != y;
		}
		return !(x == y);
		}

		// comparison with T
		@@ -457,6 +451,194 @@ constexpr bool operator!=(const unexpected<E2>& x, const expected<T1, E1>& y) {
		return y.has_value() \|\| (x.value() != y.error());
		}

		template<class E>
		class _NODISCARD_ expected<void, E> {
		public:
		using value_type = void;
		using error_type = E;
		using unexpected_type = unexpected<E>;

		// constructors
		constexpr expected() = default;
		constexpr expected(const expected& rhs) = default;
		constexpr expected(expected&& rhs) noexcept = default;

		template<class U, class G _ENABLE_IF(
		std::is_void_v<U> &&
		std::is_convertible_v<const G&, E> /* non-explicit */
		)>
		constexpr expected(const expected<U, G>& rhs) {
		if (!rhs.has_value()) var_ = unexpected(rhs.error());
		}

		template<class U, class G _ENABLE_IF(
		std::is_void_v<U> &&
		!std::is_convertible_v<const G&, E> /* explicit */
		)>
		constexpr explicit expected(const expected<U, G>& rhs) {
		if (!rhs.has_value()) var_ = unexpected(rhs.error());
		}

		template<class U, class G _ENABLE_IF(
		std::is_void_v<U> &&
		std::is_convertible_v<const G&&, E> /* non-explicit */
		)>
		constexpr expected(expected<U, G>&& rhs) {
		if (!rhs.has_value()) var_ = unexpected(std::move(rhs.error()));
		}

		template<class U, class G _ENABLE_IF(
		std::is_void_v<U> &&
		!std::is_convertible_v<const G&&, E> /* explicit */
		)>
		constexpr explicit expected(expected<U, G>&& rhs) {
		if (!rhs.has_value()) var_ = unexpected(std::move(rhs.error()));
		}

		template<class G = E _ENABLE_IF(
		std::is_constructible_v<E, const G&> &&
		std::is_convertible_v<const G&, E> /* non-explicit */
		)>
		constexpr expected(const unexpected<G>& e)
		: var_(std::in_place_index<1>, e.value()) {}

		template<class G = E _ENABLE_IF(
		std::is_constructible_v<E, const G&> &&
		!std::is_convertible_v<const G&, E> /* explicit */
		)>
		constexpr explicit expected(const unexpected<G>& e)
		: var_(std::in_place_index<1>, E(e.value())) {}

		template<class G = E _ENABLE_IF(
		std::is_constructible_v<E, G&&> &&
		std::is_convertible_v<G&&, E> /* non-explicit */
		)>
		constexpr expected(unexpected<G>&& e)
		: var_(std::in_place_index<1>, std::move(e.value())) {}

		template<class G = E _ENABLE_IF(
		std::is_constructible_v<E, G&&> &&
		!std::is_convertible_v<G&&, E> /* explicit */
		)>
		constexpr explicit expected(unexpected<G>&& e)
		: var_(std::in_place_index<1>, E(std::move(e.value()))) {}

		template<class... Args _ENABLE_IF(
		sizeof...(Args) == 0
		)>
		constexpr explicit expected(std::in_place_t, Args&&...) {}

		template<class... Args _ENABLE_IF(
		std::is_constructible_v<E, Args...>
		)>
		constexpr explicit expected(unexpect_t, Args&&... args)
		: var_(unexpected_type(std::forward<Args>(args)...)) {}

		template<class U, class... Args _ENABLE_IF(
		std::is_constructible_v<E, std::initializer_list<U>&, Args...>
		)>
		constexpr explicit expected(unexpect_t, std::initializer_list<U> il, Args&&... args)
		: var_(unexpected_type(il, std::forward<Args>(args)...)) {}

		// destructor
		~expected() = default;

		// assignment
		// Note: SFNAIE doesn't work here because assignment operator should be
		// non-template. We could workaround this by defining a templated parent class
		// having the assignment operator. This incomplete implementation however
		// doesn't allow us to copy assign expected<T,E> even when T is non-copy
		// assignable. The copy assignment will fail by the underlying std::variant
		// anyway though the error message won't be clear.
		expected& operator=(const expected& rhs) = default;

		// Note for SFNAIE above applies to here as well
		expected& operator=(expected&& rhs) = default;

		template<class G = E>
		expected& operator=(const unexpected<G>& rhs) {
		var_ = rhs;
		return *this;
		}

		template<class G = E _ENABLE_IF(
		std::is_nothrow_move_constructible_v<G> &&
		std::is_move_assignable_v<G>
		)>
		expected& operator=(unexpected<G>&& rhs) {
		var_ = std::move(rhs);
		return *this;
		}

		// modifiers
		void emplace() {
		var_ = std::monostate();
		}

		// swap
		template<typename = std::enable_if_t<
		std::is_swappable_v<E>>
		>
		void swap(expected& rhs) noexcept(std::is_nothrow_move_constructible_v<E>) {
		var_.swap(rhs.var_);
		}

		// observers
		constexpr explicit operator bool() const noexcept { return has_value(); }
		constexpr bool has_value() const noexcept { return var_.index() == 0; }

		constexpr void value() const& { if (!has_value()) std::get<0>(var_); }

		constexpr const E& error() const& { return std::get<unexpected_type>(var_).value(); }
		constexpr E& error() & { return std::get<unexpected_type>(var_).value(); }
		constexpr const E&& error() const&& { return std::move(std::get<unexpected_type>(var_)).value(); }
		constexpr E&& error() && { return std::move(std::get<unexpected_type>(var_)).value(); }

		// expected equality operators
		template<class E1, class E2>
		friend constexpr bool operator==(const expected<void, E1>& x, const expected<void, E2>& y);

		// Specialized algorithms
		template<class T1, class E1>
		friend void swap(expected<T1, E1>&, expected<T1, E1>&) noexcept;

		private:
		std::variant<std::monostate, unexpected_type> var_;
		};

		template<class E1, class E2>
		constexpr bool operator==(const expected<void, E1>& x, const expected<void, E2>& y) {
		if (x.has_value() != y.has_value()) {
		return false;
		} else if (!x.has_value()) {
		return x.error() == y.error();
		} else {
		return true;
		}
		}

		template<class T1, class E1, class E2>
		constexpr bool operator==(const expected<T1, E1>& x, const expected<void, E2>& y) {
		if (x.has_value() != y.has_value()) {
		return false;
		} else if (!x.has_value()) {
		return x.error() == y.error();
		} else {
		return false;
		}
		}

		template<class E1, class T2, class E2>
		constexpr bool operator==(const expected<void, E1>& x, const expected<T2, E2>& y) {
		if (x.has_value() != y.has_value()) {
		return false;
		} else if (!x.has_value()) {
		return x.error() == y.error();
		} else {
		return false;
		}
		}

		template<class E>
		class unexpected {
		public:

base/include/android-base/result.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -98,6 +98,14 @@ struct ResultError {
		int code_;
		};

		inline bool operator==(const ResultError& lhs, const ResultError& rhs) {
		return lhs.message() == rhs.message() && lhs.code() == rhs.code();
		}

		inline bool operator!=(const ResultError& lhs, const ResultError& rhs) {
		return !(lhs == rhs);
		}

		inline std::ostream& operator<<(std::ostream& os, const ResultError& t) {
		os << t.message();
		return os;

base/result_test.cpp

+25 −0

Original line number	Diff line number	Diff line
		@@ -70,6 +70,31 @@ TEST(result, result_success_rvalue) {
		EXPECT_EQ(Success(), MakeRvalueSuccessResult().value());
		}

		TEST(result, result_void) {
		Result<void> ok = {};
		EXPECT_TRUE(ok);
		ok.value(); // should not crash
		ASSERT_DEATH(ok.error(), "");

		Result<void> fail = Error() << "failure" << 1;
		EXPECT_FALSE(fail);
		EXPECT_EQ("failure1", fail.error().message());
		EXPECT_EQ(0, fail.error().code());
		EXPECT_TRUE(ok != fail);
		ASSERT_DEATH(fail.value(), "");

		auto test = [](bool ok) -> Result<void> {
		if (ok) return {};
		else return Error() << "failure" << 1;
		};
		EXPECT_TRUE(test(true));
		EXPECT_FALSE(test(false));
		test(true).value(); // should not crash
		ASSERT_DEATH(test(true).error(), "");
		ASSERT_DEATH(test(false).value(), "");
		EXPECT_EQ("failure1", test(false).error().message());
		}

		TEST(result, result_error) {
		Result<Success> result = Error() << "failure" << 1;
		ASSERT_FALSE(result);