Add qOverload to select overloaded functions

[ChangeLog][QtCore][Global] qOverload added to select
overloaded functions.

Change-Id: I7c9b1b054e6631eca0b5594db59e1202ef552c33
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
This commit is contained in:
Peter Kümmel 2015-11-10 18:57:40 +01:00 committed by Olivier Goffart (Woboq GmbH)
parent e41e034669
commit ab8cc8387f
5 changed files with 254 additions and 0 deletions

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@ -568,6 +568,29 @@ struct A : public B {
template<> class QTypeInfo<A> : public QTypeInfoMerger<A, B, C, D> {};
//! [51]
//! [52]
struct Foo {
void overloadedFunction();
void overloadedFunction(int, QString);
};
... qOverload<>(&Foo:overloadedFunction)
... qOverload<int, QString>(&Foo:overloadedFunction)
//! [52]
//! [53]
... QOverload<>::of(&Foo:overloadedFunction)
... QOverload<int, QString>::of(&Foo:overloadedFunction)
//! [53]
//! [54]
struct Foo {
void overloadedFunction(int, QString);
void overloadedFunction(int, QString) const;
};
... qConstOverload<>(&Foo:overloadedFunction)
... qNonConstOverload<int, QString>(&Foo:overloadedFunction)
//! [54]
//! [qlikely]
// the condition inside the "if" will be successful most of the times
for (int i = 1; i <= 365; i++) {

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@ -921,6 +921,49 @@ Q_STATIC_ASSERT_X(QT_POINTER_SIZE == sizeof(void *), "QT_POINTER_SIZE defined in
\sa qMin(), qMax()
*/
/*! \fn auto qOverload(T functionPointer)
\relates <QtGlobal>
\since 5.7
qOverload() returns a pointer to an overloaded function. The template
parameter is the list of the argument types of the function.
\a functionPointer is the pointer to the (member) function:
\snippet code/src_corelib_global_qglobal.cpp 52
If a member function is also const-overladed \l qConstOverload and
\l qNonConstOverload needs to be used.
qOverload() needs C++14 enabled. In C++11 only code the helper
classes QOverload, QConstOverload, and QNonConstOverload could be used directly:
\snippet code/src_corelib_global_qglobal.cpp 53
\sa qConstOverload(), qNonConstOverload()
*/
/*! \fn auto qConstOverload(T memberFunctionPointer)
\relates <QtGlobal>
\since 5.7
qConstOverload() returns a pointer to an constant member function:
\snippet code/src_corelib_global_qglobal.cpp 54
\sa qOverload, qNonConstOverload
*/
/*! \fn auto qNonConstOverload(T memberFunctionPointer)
\relates <QtGlobal>
\since 5.7
qNonConstOverload() eturns a pointer to an non constant member function:
\snippet code/src_corelib_global_qglobal.cpp 54
\sa qOverload, qNonConstOverload
*/
/*!
\macro QT_VERSION_CHECK
\relates <QtGlobal>

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@ -1018,6 +1018,66 @@ Q_CORE_EXPORT QString qtTrId(const char *id, int n = -1);
{ return T::dynamic_cast_will_always_fail_because_rtti_is_disabled; }
#endif
#ifdef Q_QDOC
// Just for documentation generation
auto qOverload(T functionPointer);
auto qConstOverload(T memberFunctionPointer);
auto qNonConstOverload(T memberFunctionPointer);
#elif defined(Q_COMPILER_VARIADIC_TEMPLATES)
template <typename... Args>
struct QNonConstOverload
{
template <typename R, typename T>
Q_DECL_CONSTEXPR auto operator()(R (T::*ptr)(Args...)) const Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
template <typename R, typename T>
static Q_DECL_CONSTEXPR auto of(R (T::*ptr)(Args...)) Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
};
template <typename... Args>
struct QConstOverload
{
template <typename R, typename T>
Q_DECL_CONSTEXPR auto operator()(R (T::*ptr)(Args...) const) const Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
template <typename R, typename T>
static Q_DECL_CONSTEXPR auto of(R (T::*ptr)(Args...) const) Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
};
template <typename... Args>
struct QOverload : QConstOverload<Args...>, QNonConstOverload<Args...>
{
using QConstOverload<Args...>::of;
using QConstOverload<Args...>::operator();
using QNonConstOverload<Args...>::of;
using QNonConstOverload<Args...>::operator();
template <typename R>
Q_DECL_CONSTEXPR auto operator()(R (*ptr)(Args...)) const Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
template <typename R>
static Q_DECL_CONSTEXPR auto of(R (*ptr)(Args...)) Q_DECL_NOTHROW -> decltype(ptr)
{ return ptr; }
};
#if defined(__cpp_variable_templates) && __cpp_variable_templates >= 201304 // C++14
template <typename... Args> Q_CONSTEXPR QOverload<Args...> qOverload Q_DECL_UNUSED = {};
template <typename... Args> Q_CONSTEXPR QConstOverload<Args...> qConstOverload Q_DECL_UNUSED = {};
template <typename... Args> Q_CONSTEXPR QNonConstOverload<Args...> qNonConstOverload Q_DECL_UNUSED = {};
#endif
#endif
class QByteArray;
Q_CORE_EXPORT QByteArray qgetenv(const char *varName);
Q_CORE_EXPORT bool qputenv(const char *varName, const QByteArray& value);

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@ -4538,6 +4538,8 @@ void qDeleteInEventHandler(QObject *o)
make sure to declare the argument type with Q_DECLARE_METATYPE
Overloaded functions can be resolved with help of \l qOverload.
\note The number of arguments in the signal or slot are limited to 6 if
the compiler does not support C++11 variadic templates.
*/
@ -4573,6 +4575,8 @@ void qDeleteInEventHandler(QObject *o)
However, you should take care that any objects used within the functor
are still alive when the signal is emitted.
Overloaded functions can be resolved with help of \l qOverload.
\note If the compiler does not support C++11 variadic templates, the number
of arguments in the signal or slot are limited to 6, and the functor object
must not have an overloaded or templated operator().
@ -4612,6 +4616,8 @@ void qDeleteInEventHandler(QObject *o)
However, you should take care that any objects used within the functor
are still alive when the signal is emitted.
Overloaded functions can be resolved with help of \l qOverload.
\note If the compiler does not support C++11 variadic templates, the number
of arguments in the signal or slot are limited to 6, and the functor object
must not have an overloaded or templated operator().

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@ -55,6 +55,7 @@ private slots:
void qprintable();
void qprintable_data();
void buildAbiEndianness();
void testqOverload();
};
void tst_QGlobal::qIsNull()
@ -652,5 +653,126 @@ void tst_QGlobal::buildAbiEndianness()
QVERIFY(QSysInfo::buildAbi().contains(endian));
}
struct Overloaded
{
void foo() {}
void foo(QByteArray) {}
void foo(QByteArray, const QString &) {}
void constFoo() const {}
void constFoo(QByteArray) const {}
void constFoo(QByteArray, const QString &) const {}
void mixedFoo() {}
void mixedFoo(QByteArray) const {}
};
void freeOverloaded() {}
void freeOverloaded(QByteArray) {}
void freeOverloaded(QByteArray, const QString &) {}
void freeOverloadedGet(QByteArray) {}
QByteArray freeOverloadedGet() { return QByteArray(); }
void tst_QGlobal::testqOverload()
{
#ifdef Q_COMPILER_VARIADIC_TEMPLATES
// void returning free overloaded functions
QVERIFY(QOverload<>::of(&freeOverloaded) ==
static_cast<void (*)()>(&freeOverloaded));
QVERIFY(QOverload<QByteArray>::of(&freeOverloaded) ==
static_cast<void (*)(QByteArray)>(&freeOverloaded));
QVERIFY((QOverload<QByteArray, const QString &>::of(&freeOverloaded)) ==
static_cast<void (*)(QByteArray, const QString &)>(&freeOverloaded));
// value returning free overloaded functions
QVERIFY(QOverload<>::of(&freeOverloadedGet) ==
static_cast<QByteArray (*)()>(&freeOverloadedGet));
QVERIFY(QOverload<QByteArray>::of(&freeOverloadedGet) ==
static_cast<void (*)(QByteArray)>(&freeOverloadedGet));
// void returning overloaded member functions
QVERIFY(QOverload<>::of(&Overloaded::foo) ==
static_cast<void (Overloaded::*)()>(&Overloaded::foo));
QVERIFY(QOverload<QByteArray>::of(&Overloaded::foo) ==
static_cast<void (Overloaded::*)(QByteArray)>(&Overloaded::foo));
QVERIFY((QOverload<QByteArray, const QString &>::of(&Overloaded::foo)) ==
static_cast<void (Overloaded::*)(QByteArray, const QString &)>(&Overloaded::foo));
// void returning overloaded const member functions
QVERIFY(QOverload<>::of(&Overloaded::constFoo) ==
static_cast<void (Overloaded::*)() const>(&Overloaded::constFoo));
QVERIFY(QOverload<QByteArray>::of(&Overloaded::constFoo) ==
static_cast<void (Overloaded::*)(QByteArray) const>(&Overloaded::constFoo));
QVERIFY((QOverload<QByteArray, const QString &>::of(&Overloaded::constFoo)) ==
static_cast<void (Overloaded::*)(QByteArray, const QString &) const>(&Overloaded::constFoo));
// void returning overloaded const AND non-const member functions
QVERIFY(QNonConstOverload<>::of(&Overloaded::mixedFoo) ==
static_cast<void (Overloaded::*)()>(&Overloaded::mixedFoo));
QVERIFY(QConstOverload<QByteArray>::of(&Overloaded::mixedFoo) ==
static_cast<void (Overloaded::*)(QByteArray) const>(&Overloaded::mixedFoo));
#if defined(__cpp_variable_templates) && __cpp_variable_templates >= 201304 // C++14
// void returning free overloaded functions
QVERIFY(qOverload<>(&freeOverloaded) ==
static_cast<void (*)()>(&freeOverloaded));
QVERIFY(qOverload<QByteArray>(&freeOverloaded) ==
static_cast<void (*)(QByteArray)>(&freeOverloaded));
QVERIFY((qOverload<QByteArray, const QString &>(&freeOverloaded)),
static_cast<void (*)(QByteArray, const QString &)>(&freeOverloaded));
// value returning free overloaded functions
QVERIFY(qOverload<>(&freeOverloadedGet) ==
static_cast<QByteArray (*)()>(&freeOverloadedGet));
QVERIFY(qOverload<QByteArray>(&freeOverloadedGet) ==
static_cast<void (*)(QByteArray)>(&freeOverloadedGet));
// void returning overloaded member functions
QVERIFY(qOverload<>(&Overloaded::foo) ==
static_cast<void (Overloaded::*)()>(&Overloaded::foo));
QVERIFY(qOverload<QByteArray>(&Overloaded::foo) ==
static_cast<void (Overloaded::*)(QByteArray)>(&Overloaded::foo));
QVERIFY((qOverload<QByteArray, const QString &>(&Overloaded::foo)) ==
static_cast<void (Overloaded::*)(QByteArray, const QString &)>(&Overloaded::foo));
// void returning overloaded const member functions
QVERIFY(qOverload<>(&Overloaded::constFoo) ==
static_cast<void (Overloaded::*)() const>(&Overloaded::constFoo));
QVERIFY(qOverload<QByteArray>(&Overloaded::constFoo) ==
static_cast<void (Overloaded::*)(QByteArray) const>(&Overloaded::constFoo));
QVERIFY((qOverload<QByteArray, const QString &>(&Overloaded::constFoo)) ==
static_cast<void (Overloaded::*)(QByteArray, const QString &) const>(&Overloaded::constFoo));
// void returning overloaded const AND non-const member functions
QVERIFY(qNonConstOverload<>(&Overloaded::mixedFoo) ==
static_cast<void (Overloaded::*)()>(&Overloaded::mixedFoo));
QVERIFY(qConstOverload<QByteArray>(&Overloaded::mixedFoo) ==
static_cast<void (Overloaded::*)(QByteArray) const>(&Overloaded::mixedFoo));
#endif
#endif
}
QTEST_APPLESS_MAIN(tst_QGlobal)
#include "tst_qglobal.moc"