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Commit f37108b

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pananton
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feat userver: add void support to utils::expected
Relates: <https://nda.ya.ru/t/wXSs-Og_7Nan57> commit_hash:6f999dc094e94f80e792b7f81aa477cee2bc4d6f
1 parent 4713600 commit f37108b

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3 files changed

+182
-2
lines changed

3 files changed

+182
-2
lines changed

‎.mapping.json‎

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@@ -5477,6 +5477,7 @@
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"universal/src/utils/encoding/tskv_test.cpp":"taxi/uservices/userver/universal/src/utils/encoding/tskv_test.cpp",
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"universal/src/utils/encoding/tskv_testdata_bin.hpp":"taxi/uservices/userver/universal/src/utils/encoding/tskv_testdata_bin.hpp",
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"universal/src/utils/enumerate_test.cpp":"taxi/uservices/userver/universal/src/utils/enumerate_test.cpp",
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"universal/src/utils/expected_test.cpp":"taxi/uservices/userver/universal/src/utils/expected_test.cpp",
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"universal/src/utils/fast_pimpl_test.cpp":"taxi/uservices/userver/universal/src/utils/fast_pimpl_test.cpp",
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"universal/src/utils/fast_scope_guard_test.cpp":"taxi/uservices/userver/universal/src/utils/fast_scope_guard_test.cpp",
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"universal/src/utils/filter_bloom_test.cpp":"taxi/uservices/userver/universal/src/utils/filter_bloom_test.cpp",

‎universal/include/userver/utils/expected.hpp‎

Lines changed: 94 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -55,7 +55,7 @@ unexpected(E) -> unexpected<E>;
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template <class S, class E>
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class [[nodiscard]] expected {
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public:
58-
constexpr expected() noexcept(std::is_void_v<S>);
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constexpr expected();
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expected(const S& success);
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expected(S&& success);
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expected(const unexpected<E>& error);
@@ -70,6 +70,9 @@ class [[nodiscard]] expected {
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/// @brief Check whether *this contains an expected value
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bool has_value() const noexcept;
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/// @brief Check whether *this contains an expected value
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explicit operator bool() const noexcept;
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/// @brief Return reference to the value or throws bad_expected_access
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/// if it's not available
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/// @throws utils::bad_expected_access if *this contain an unexpected value
@@ -93,6 +96,30 @@ class [[nodiscard]] expected {
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std::variant<S, unexpected<E>> data_;
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};
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template <class E>
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class [[nodiscard]] expected<void, E> {
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public:
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constexpr expected() noexcept;
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expected(const unexpected<E>& error);
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expected(unexpected<E>&& error);
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template <class G, typename = std::enable_if_t<std::is_convertible_v<G, E>>>
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expected(const unexpected<G>& error);
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template <class G, typename = std::enable_if_t<std::is_convertible_v<G, E>>>
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expected(unexpected<G>&& error);
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bool has_value() const noexcept;
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explicit operator bool() const noexcept;
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void value() const;
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E& error();
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const E& error() const;
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private:
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std::variant<std::monostate, unexpected<E>> data_;
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};
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template <class E>
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unexpected<E>::unexpected(const E& error)
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: value_{error}
@@ -126,7 +153,7 @@ const E& unexpected<E>::error() const noexcept {
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}
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template <class S, class E>
129-
constexpr expected<S, E>::expected() noexcept(std::is_void_v<S>)
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constexpr expected<S, E>::expected()
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: data_(std::in_place_index<0>)
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{}
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@@ -167,6 +194,11 @@ bool expected<S, E>::has_value() const noexcept {
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return std::holds_alternative<S>(data_);
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}
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template <class S, class E>
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expected<S, E>::operator bool() const noexcept {
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return has_value();
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}
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template <class S, class E>
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S& expected<S, E>::value() & {
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S* result = std::get_if<S>(&data_);
@@ -208,6 +240,66 @@ const E& expected<S, E>::error() const {
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return result->error();
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}
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template <class E>
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constexpr expected<void, E>::expected() noexcept: data_(std::in_place_index<0>) {}
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template <class E>
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expected<void, E>::expected(const unexpected<E>& error)
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: data_(error.error())
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{}
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template <class E>
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expected<void, E>::expected(unexpected<E>&& error)
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: data_(std::forward<unexpected<E>>(error.error()))
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{}
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template <class E>
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template <class G, typename>
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expected<void, E>::expected(const unexpected<G>& error)
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: data_(utils::unexpected<E>(std::forward<G>(error.error())))
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{}
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template <class E>
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template <class G, typename>
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expected<void, E>::expected(unexpected<G>&& error)
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: data_(utils::unexpected<E>(std::forward<G>(error.error())))
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{}
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template <class E>
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bool expected<void, E>::has_value() const noexcept {
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return data_.index() == 0;
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}
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template <class E>
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expected<void, E>::operator bool() const noexcept {
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return has_value();
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}
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template <class E>
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void expected<void, E>::value() const {
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if (!has_value()) {
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throw bad_expected_access("Trying to get undefined value from utils::expected");
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}
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}
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template <class E>
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E& expected<void, E>::error() {
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auto* result = std::get_if<unexpected<E>>(&data_);
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if (result == nullptr) {
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throw bad_expected_access("Trying to get undefined error value from utils::expected");
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}
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return result->error();
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}
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template <class E>
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const E& expected<void, E>::error() const {
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const auto* result = std::get_if<unexpected<E>>(&data_);
297+
if (result == nullptr) {
298+
throw bad_expected_access("Trying to get undefined error value from utils::expected");
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}
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return result->error();
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}
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// NOLINTEND(readability-identifier-naming)
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} // namespace utils

‎universal/src/utils/expected_test.cpp‎

Lines changed: 87 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,87 @@
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#include <string>
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#include <gtest/gtest.h>
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#include <userver/utils/expected.hpp>
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USERVER_NAMESPACE_BEGIN
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using ExpectedInt = utils::expected<int, std::string>;
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using ExpectedVoid = utils::expected<void, std::string>;
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TEST(Expected, DefaultCtorCreatesValue) {
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EXPECT_TRUE(ExpectedInt{}.has_value());
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EXPECT_TRUE(ExpectedInt{});
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EXPECT_EQ(ExpectedInt{}.value(), 0);
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EXPECT_TRUE(ExpectedVoid{}.has_value());
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EXPECT_TRUE(ExpectedVoid{});
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}
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TEST(Expected, ValueCtor) {
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ExpectedInt ei{5};
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EXPECT_TRUE(ei.has_value());
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EXPECT_TRUE(ei);
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ASSERT_NO_THROW(ei.value());
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EXPECT_EQ(ei.value(), 5);
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ei.value() += 10;
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EXPECT_TRUE(ei.has_value());
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EXPECT_TRUE(ei);
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EXPECT_EQ(std::move(ei).value(), 15);
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}
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TEST(Expected, ErrorCtor) {
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auto error = utils::unexpected{std::string("string error")};
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ExpectedInt ei{error};
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ExpectedVoid ev{std::move(error)};
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EXPECT_FALSE(ei.has_value());
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EXPECT_FALSE(ei);
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EXPECT_FALSE(ev.has_value());
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EXPECT_FALSE(ev);
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EXPECT_EQ(const_cast<const ExpectedInt&>(ei).error(), "string error");
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EXPECT_EQ(const_cast<const ExpectedVoid&>(ev).error(), "string error");
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48+
ei.error() = "another error";
49+
ev.error() = "one more error";
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51+
EXPECT_EQ(ei.error(), "another error");
52+
EXPECT_EQ(ev.error(), "one more error");
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54+
ei = ExpectedInt{utils::unexpected<const char*>("converted error")};
55+
ev = ExpectedVoid{utils::unexpected<const char*>("converted error")};
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57+
EXPECT_FALSE(ei.has_value());
58+
EXPECT_FALSE(ei);
59+
EXPECT_FALSE(ev.has_value());
60+
EXPECT_FALSE(ev);
61+
EXPECT_EQ(ei.error(), "converted error");
62+
EXPECT_EQ(ev.error(), "converted error");
63+
}
64+
65+
TEST(Expected, ValueThrowsIfExpectedContainsError) {
66+
auto error = utils::unexpected{std::string("string error")};
67+
68+
ExpectedInt ei{error};
69+
ExpectedVoid ev{std::move(error)};
70+
71+
EXPECT_THROW(const_cast<const ExpectedInt&>(ei).value(), utils::bad_expected_access);
72+
EXPECT_THROW(ei.value(), utils::bad_expected_access);
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EXPECT_THROW(std::move(ei).value(), utils::bad_expected_access);
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EXPECT_THROW(ev.value(), utils::bad_expected_access);
75+
}
76+
77+
TEST(Expected, ErrorThrowsIfExpectedContainsValue) {
78+
ExpectedInt ei{10};
79+
ExpectedVoid ev;
80+
81+
EXPECT_THROW(const_cast<const ExpectedInt&>(ei).error(), utils::bad_expected_access);
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EXPECT_THROW(ei.error(), utils::bad_expected_access);
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EXPECT_THROW(const_cast<const ExpectedVoid&>(ev).error(), utils::bad_expected_access);
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EXPECT_THROW(ev.error(), utils::bad_expected_access);
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}
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USERVER_NAMESPACE_END

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