diff options
author | Marc Mutz <marc.mutz@qt.io> | 2023-05-31 16:34:01 +0200 |
---|---|---|
committer | Marc Mutz <marc.mutz@qt.io> | 2023-06-02 20:32:11 +0000 |
commit | 8983225d3c20967d23b23d3071988a66df4e29f5 (patch) | |
tree | feccea8001a39670a8fff376a350e9a269a780a4 | |
parent | 79ae79d05c65019233cf9ae9e77ef59d90e75ac2 (diff) |
QVariant: add rvalue overload of fromStdVariant()
Extract Method fromStdVariantImpl() to share the otherwise
more-or-less identical implementation between the two overloads.
Don't use a constrained template version of fromStdVariantImpl() as
fromStdVariant(), because the constraint would have to be very complex
to continue allowing subclasses of std::variant to be passed.
As a drive-by, mark the valueless_by_exception() path Q_UNLIKELY.
[ChangeLog][QtCore][QVariant] Added overload of fromStdVariant()
taking rvalue std::variant<>s.
Fixes: QTBUG-114134
Change-Id: Ia1c7ae93ab421e6689dc9f2d8d0c2295b23cbbf6
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
-rw-r--r-- | src/corelib/kernel/qvariant.cpp | 6 | ||||
-rw-r--r-- | src/corelib/kernel/qvariant.h | 21 | ||||
-rw-r--r-- | tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp | 45 |
3 files changed, 69 insertions, 3 deletions
diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp index 8e2457350c..30da12c95b 100644 --- a/src/corelib/kernel/qvariant.cpp +++ b/src/corelib/kernel/qvariant.cpp @@ -2722,6 +2722,12 @@ QT_WARNING_POP */ /*! + \fn template<typename... Types> QVariant QVariant::fromStdVariant(std::variant<Types...> &&value) + \since 6.6 + \overload +*/ + +/*! \fn template<typename T> T qvariant_cast(const QVariant &value) \relates QVariant diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h index 582f135fab..fe99ad6bdd 100644 --- a/src/corelib/kernel/qvariant.h +++ b/src/corelib/kernel/qvariant.h @@ -569,9 +569,13 @@ public: template<typename... Types> static inline QVariant fromStdVariant(const std::variant<Types...> &value) { - if (value.valueless_by_exception()) - return QVariant(); - return std::visit([](const auto &arg) { return QVariant::fromValue(arg); }, value); + return fromStdVariantImpl(value); + } + + template<typename... Types> + static QVariant fromStdVariant(std::variant<Types...> &&value) + { + return fromStdVariantImpl(std::move(value)); } template<typename T> @@ -585,6 +589,17 @@ public: static QPartialOrdering compare(const QVariant &lhs, const QVariant &rhs); private: + template <typename StdVariant> + static QVariant fromStdVariantImpl(StdVariant &&v) + { + if (Q_UNLIKELY(v.valueless_by_exception())) + return QVariant(); + auto visitor = [](auto &&arg) { + return QVariant::fromValue(q23::forward_like<StdVariant>(arg)); + }; + return std::visit(visitor, std::forward<StdVariant>(v)); + } + friend inline bool operator==(const QVariant &a, const QVariant &b) { return a.equals(b); } friend inline bool operator!=(const QVariant &a, const QVariant &b) diff --git a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp index addf7ceec9..23fa969edd 100644 --- a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp +++ b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp @@ -5392,6 +5392,16 @@ void tst_QVariant::shouldDeleteVariantDataWorksForAssociative() void tst_QVariant::fromStdVariant() { +#define CHECK_EQUAL(lhs, rhs, type) do { \ + QCOMPARE(lhs.typeId(), rhs.typeId()); \ + if (lhs.isNull()) { \ + QVERIFY(rhs.isNull()); \ + } else { \ + QVERIFY(!rhs.isNull()); \ + QCOMPARE(get< type >(lhs), get< type >(rhs)); \ + } \ + } while (false) + { typedef std::variant<int, bool> intorbool_t; intorbool_t stdvar = 5; @@ -5399,21 +5409,38 @@ void tst_QVariant::fromStdVariant() QVERIFY(!qvar.isNull()); QCOMPARE(qvar.typeId(), QMetaType::Int); QCOMPARE(qvar.value<int>(), std::get<int>(stdvar)); + { + const auto qv2 = QVariant::fromStdVariant(std::move(stdvar)); + CHECK_EQUAL(qv2, qvar, int); + } + stdvar = true; qvar = QVariant::fromStdVariant(stdvar); QVERIFY(!qvar.isNull()); QCOMPARE(qvar.typeId(), QMetaType::Bool); QCOMPARE(qvar.value<bool>(), std::get<bool>(stdvar)); + { + const auto qv2 = QVariant::fromStdVariant(std::move(stdvar)); + CHECK_EQUAL(qv2, qvar, bool); + } } { std::variant<std::monostate, int> stdvar; QVariant qvar = QVariant::fromStdVariant(stdvar); QVERIFY(!qvar.isValid()); + { + const auto qv2 = QVariant::fromStdVariant(std::move(stdvar)); + CHECK_EQUAL(qv2, qvar, int); // fake type, they're empty + } stdvar = -4; qvar = QVariant::fromStdVariant(stdvar); QVERIFY(!qvar.isNull()); QCOMPARE(qvar.typeId(), QMetaType::Int); QCOMPARE(qvar.value<int>(), std::get<int>(stdvar)); + { + const auto qv2 = QVariant::fromStdVariant(std::move(stdvar)); + CHECK_EQUAL(qv2, qvar, int); + } } { std::variant<int, bool, QChar> stdvar = QChar::fromLatin1(' '); @@ -5421,7 +5448,25 @@ void tst_QVariant::fromStdVariant() QVERIFY(!qvar.isNull()); QCOMPARE(qvar.typeId(), QMetaType::QChar); QCOMPARE(qvar.value<QChar>(), std::get<QChar>(stdvar)); + { + const auto qv2 = QVariant::fromStdVariant(std::move(stdvar)); + CHECK_EQUAL(qv2, qvar, QChar); + } } + // rvalue fromStdVariant() actually moves: + { + const auto foo = u"foo"_s; + std::variant<QString, QByteArray> stdvar = foo; + QVariant qvar = QVariant::fromStdVariant(std::move(stdvar)); + const auto ps = get_if<QString>(&stdvar); + QVERIFY(ps); + QVERIFY(ps->isNull()); // QString was moved from + QVERIFY(!qvar.isNull()); + QCOMPARE(qvar.typeId(), QMetaType::QString); + QCOMPARE(get<QString>(qvar), foo); + } + +#undef CHECK_EQUAL } void tst_QVariant::qt4UuidDataStream() |