Add expected<void,E>
Result<void> could be used instead of Result<Success>.
Bug: 132145659
Test: libbase_test
Change-Id: I7f079a94d06c5ecb8b0303ced981f0995253dc40
diff --git a/base/expected_test.cpp b/base/expected_test.cpp
index 490ced4..a74bc1d 100644
--- a/base/expected_test.cpp
+++ b/base/expected_test.cpp
@@ -29,6 +29,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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;
diff --git a/base/include/android-base/expected.h b/base/include/android-base/expected.h
index 2307217..08c9fb5 100644
--- a/base/include/android-base/expected.h
+++ b/base/include/android-base/expected.h
@@ -412,13 +412,7 @@
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
@@ -458,6 +452,194 @@
}
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:
// constructors
diff --git a/base/include/android-base/result.h b/base/include/android-base/result.h
index 3cb39e6..8f00710 100644
--- a/base/include/android-base/result.h
+++ b/base/include/android-base/result.h
@@ -98,6 +98,14 @@
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;
diff --git a/base/result_test.cpp b/base/result_test.cpp
index 6874889..d31e775 100644
--- a/base/result_test.cpp
+++ b/base/result_test.cpp
@@ -70,6 +70,31 @@
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);