qt-creator/tests/auto/mapreduce/tst_mapreduce.cpp

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#include <utils/algorithm.h>
#include <utils/mapreduce.h>

#include <QtTest>

class tst_MapReduce : public QObject
{
    Q_OBJECT

private slots:
    void mapReduce();
    void mapReduceRvalueContainer();
    void map();
};

static int returnxx(int x)
{
    return x*x;
}

static void returnxxThroughFutureInterface(QFutureInterface<int> &fi, int x)
{
    fi.reportResult(x*x);
}

void tst_MapReduce::mapReduce()
{
    const auto dummyInit = [](QFutureInterface<double>& fi) -> double {
        fi.reportResult(0.);
        return 0.;
    };
    const auto reduceWithFutureInterface = [](QFutureInterface<double>& fi, double &state, int value) {
        state += value;
        fi.reportResult(value);
    };
    const auto reduceWithReturn = [](double &state, int value) -> double {
        state += value;
        return value;
    };
    const auto cleanupHalfState = [](QFutureInterface<double> &fi, double &state) {
        state /= 2.;
        fi.reportResult(state);
    };

    // TODO: cannot use function returnxx without pointer here because of decayCopy of arguments in runAsync
    {
        QList<double> results = Utils::mapReduce(QList<int>({1, 2, 3, 4, 5}),
                                                 dummyInit, &returnxx,
                                                 reduceWithFutureInterface, cleanupHalfState)
                .results();
        Utils::sort(results); // mapping order is undefined
        QCOMPARE(results, QList<double>({0., 1., 4., 9., 16., 25., 27.5}));
    }
    {
        QList<double> results = Utils::mapReduce(QList<int>({1, 2, 3, 4, 5}),
                                                 dummyInit, &returnxxThroughFutureInterface,
                                                 reduceWithFutureInterface, cleanupHalfState)
                .results();
        Utils::sort(results); // mapping order is undefined
        QCOMPARE(results, QList<double>({0., 1., 4., 9., 16., 25., 27.5}));
    }
    {
        QList<double> results = Utils::mapReduce(QList<int>({1, 2, 3, 4, 5}),
                                                 dummyInit, &returnxx,
                                                 reduceWithReturn, cleanupHalfState)
                .results();
        Utils::sort(results); // mapping order is undefined
        QCOMPARE(results, QList<double>({0., 1., 4., 9., 16., 25., 27.5}));
    }
}

void tst_MapReduce::mapReduceRvalueContainer()
{
    {
        QFuture<int> future = Utils::mapReduce(QList<int>({1, 2, 3, 4, 5}),
                                                 [](QFutureInterface<int>&) { return 0; },
                                                 [](int value) { return value; },
                                                 [](QFutureInterface<int>&, int &state, int value) { state += value; },
                                                 [](QFutureInterface<int> &fi, int &state) { fi.reportResult(state); });
        // here, lifetime of the QList temporary ends
        QCOMPARE(future.results(), QList<int>({15}));
    }
}

void tst_MapReduce::map()
{
    {
        QList<double> results = Utils::map(QList<int>({2, 5, 1}),
                    [](int x) { return x*2.5; }
        ).results();
        Utils::sort(results);
        QCOMPARE(results, QList<double>({2.5, 5., 12.5}));
    }
    {
        // void result
        QList<int> results;
        QMutex mutex;
        Utils::map(
                    // container
                    QList<int>({2, 5, 1}),
                    // map
                    [&mutex, &results](int x) { QMutexLocker l(&mutex); results.append(x); }
                    ).waitForFinished();
        Utils::sort(results); // mapping order is undefined
        QCOMPARE(results, QList<int>({1, 2, 5}));
    }
}

QTEST_MAIN(tst_MapReduce)

#include "tst_mapreduce.moc"