tst_qpair.cpp

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/****************************************************************************
**
** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the test suite of the Qt Toolkit.
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#include <QTest>
 
#include <QPair>
#include <QSize>
 
class tst_QPair : public QObject
{
    Q_OBJECT
private Q_SLOTS:
    void pairOfReferences();
    void structuredBindings();
    void testConstexpr();
    void testConversions();
    void taskQTBUG_48780_pairContainingCArray();
    void testDeductionRules();
};
 
class C { C() {} ~C() {} Q_DECL_UNUSED_MEMBER char _[4]; };
class M { M() {} Q_DECL_UNUSED_MEMBER char _[4]; };
class P { Q_DECL_UNUSED_MEMBER char _[4]; };
 
QT_BEGIN_NAMESPACE
Q_DECLARE_TYPEINFO(M, Q_RELOCATABLE_TYPE);
Q_DECLARE_TYPEINFO(P, Q_PRIMITIVE_TYPE);
QT_END_NAMESPACE
 
// avoid the comma:
typedef QPair<C,C> QPairCC;
typedef QPair<C,M> QPairCM;
typedef QPair<C,P> QPairCP;
typedef QPair<M,C> QPairMC;
typedef QPair<M,M> QPairMM;
typedef QPair<M,P> QPairMP;
typedef QPair<P,C> QPairPC;
typedef QPair<P,M> QPairPM;
typedef QPair<P,P> QPairPP;
 
static_assert( QTypeInfo<QPairCC>::isComplex);
static_assert( !QTypeInfo<QPairCC>::isRelocatable );
 
static_assert( QTypeInfo<QPairCM>::isComplex);
static_assert( !QTypeInfo<QPairCM>::isRelocatable );
 
static_assert( QTypeInfo<QPairCP>::isComplex);
static_assert( !QTypeInfo<QPairCP>::isRelocatable );
 
static_assert( QTypeInfo<QPairMC>::isComplex);
static_assert( !QTypeInfo<QPairMC>::isRelocatable );
 
static_assert( QTypeInfo<QPairMM>::isComplex);
static_assert( QTypeInfo<QPairMM>::isRelocatable );
 
static_assert( QTypeInfo<QPairMP>::isComplex);
static_assert( QTypeInfo<QPairMP>::isRelocatable );
 
static_assert( QTypeInfo<QPairPC>::isComplex);
static_assert( !QTypeInfo<QPairPC>::isRelocatable );
 
static_assert( QTypeInfo<QPairPM>::isComplex);
static_assert( QTypeInfo<QPairPM>::isRelocatable );
 
static_assert(!QTypeInfo<QPairPP>::isComplex);
static_assert( QTypeInfo<QPairPP>::isRelocatable );
 
static_assert(!QTypeInfo<QPairPP>::isPointer);
 
 
void tst_QPair::pairOfReferences()
{
    int i = 0;
    QString s;
 
    QPair<int&, QString&> p(i, s);
 
    p.first = 1;
    QCOMPARE(i, 1);
 
    i = 2;
    QCOMPARE(p.first, 2);
 
    p.second = QLatin1String("Hello");
    QCOMPARE(s, QLatin1String("Hello"));
 
    s = QLatin1String("olleH");
    QCOMPARE(p.second, QLatin1String("olleH"));
 
    QPair<int&, QString&> q = p;
    q.first = 3;
    QCOMPARE(i, 3);
    QCOMPARE(p.first, 3);
 
    q.second = QLatin1String("World");
    QCOMPARE(s, QLatin1String("World"));
    QCOMPARE(p.second, QLatin1String("World"));
}
 
void tst_QPair::structuredBindings()
{
    using PV = QPair<int, QString>;
    using PR = QPair<int&, const QString&>;
 
    {
        PV pv = {42, "Hello"};
        PR pr = {pv.first, pv.second};
 
        auto [fv, sv] = pv;
 
        fv = 24;
        sv = "World";
        QCOMPARE(fv, 24);
        QCOMPARE(sv, "World");
        QCOMPARE(pv.first, 42);
        QCOMPARE(pv.second, "Hello");
 
        auto [fr, sr] = pr;
 
        fr = 2424;
        // sr = "World"; // const
        QCOMPARE(fr, 2424);
        QCOMPARE(pv.first, 2424);
    }
 
    {
        PV pv = {42, "Hello"};
        PR pr = {pv.first, pv.second};
 
        auto& [fv, sv] = pv;
 
        fv = 24;
        sv = "World";
        QCOMPARE(fv, 24);
        QCOMPARE(sv, "World");
        QCOMPARE(pv.first, 24);
        QCOMPARE(pv.second, "World");
 
        auto& [fr, sr] = pr;
 
        fr = 4242;
        //sr = "2World"; // const
 
        QCOMPARE(fr, 4242);
        QCOMPARE(pr.first, 4242);
        QCOMPARE(pv.first, 4242);
    }
}
 
void tst_QPair::testConstexpr()
{
    constexpr QPair<int, double> pID = qMakePair(0, 0.0);
    Q_UNUSED(pID);
 
    constexpr QPair<double, double> pDD  = qMakePair(0.0, 0.0);
    constexpr QPair<double, double> pDD2 = qMakePair(0, 0.0);   // involes (rvalue) conversion ctor
    constexpr bool equal = pDD2 == pDD;
    QVERIFY(equal);
 
    constexpr QPair<QSize, int> pSI = qMakePair(QSize(4, 5), 6);
    Q_UNUSED(pSI);
}
 
void tst_QPair::testConversions()
{
    // construction from lvalue:
    {
        const QPair<int, double> rhs(42, 4.5);
        const QPair<int, int> pii = rhs;
        QCOMPARE(pii.first, 42);
        QCOMPARE(pii.second, 4);
 
        const QPair<int, float> pif = rhs;
        QCOMPARE(pif.first, 42);
        QCOMPARE(pif.second, 4.5f);
    }
 
    // assignment from lvalue:
    {
        const QPair<int, double> rhs(42, 4.5);
        QPair<int, int> pii;
        pii = rhs;
        QCOMPARE(pii.first, 42);
        QCOMPARE(pii.second, 4);
 
        QPair<int, float> pif;
        pif = rhs;
        QCOMPARE(pif.first, 42);
        QCOMPARE(pif.second, 4.5f);
    }
 
    // construction from rvalue:
    {
#define rhs qMakePair(42, 4.5)
        const QPair<int, int> pii = rhs;
        QCOMPARE(pii.first, 42);
        QCOMPARE(pii.second, 4);
 
        const QPair<int, float> pif = rhs;
        QCOMPARE(pif.first, 42);
        QCOMPARE(pif.second, 4.5f);
#undef rhs
    }
 
    // assignment from rvalue:
    {
#define rhs qMakePair(42, 4.5)
        QPair<int, int> pii;
        pii = rhs;
        QCOMPARE(pii.first, 42);
        QCOMPARE(pii.second, 4);
 
        QPair<int, float> pif;
        pif = rhs;
        QCOMPARE(pif.first, 42);
        QCOMPARE(pif.second, 4.5f);
#undef rhs
    }
}
 
void tst_QPair::taskQTBUG_48780_pairContainingCArray()
{
    // compile-only:
    QPair<int[2], int> pair;
    pair.first[0] = 0;
    pair.first[1] = 1;
    pair.second = 2;
    Q_UNUSED(pair);
}
 
void tst_QPair::testDeductionRules()
{
#if defined(__cpp_deduction_guides) && __cpp_deduction_guides >= 201907L
    QPair p1{1, 2};
    static_assert(std::is_same<decltype(p1)::first_type, decltype(1)>::value);
    static_assert(std::is_same<decltype(p1)::second_type, decltype(2)>::value);
    QCOMPARE(p1.first, 1);
    QCOMPARE(p1.second, 2);
 
    QPair p2{QString("string"), 2};
    static_assert(std::is_same<decltype(p2)::first_type, QString>::value);
    static_assert(std::is_same<decltype(p2)::second_type, decltype(2)>::value);
    QCOMPARE(p2.first, "string");
    QCOMPARE(p2.second, 2);
 
    QPair p3(p2);
    static_assert(std::is_same<decltype(p3)::first_type, decltype(p2)::first_type>::value);
    static_assert(std::is_same<decltype(p3)::second_type, decltype(p2)::second_type>::value);
    QCOMPARE(p3.first, "string");
    QCOMPARE(p3.second, 2);
#else
    QSKIP("Unsupported (requires C++20's CTAD for aliases)");
#endif
}
 
QTEST_APPLESS_MAIN(tst_QPair)
#include "tst_qpair.moc"