mappedReduced Example

#include <QApplication>
#include <QList>
#include <Map>
#include <QGridLayout>
#include <QStandardItemModel>
#include <QLineEdit>
#include <QPushButton>
#include <QListView>
#include <QFutureWatcher>
#include <QtConcurrent>
#include <functional>

struct Result
{
  QString text;
  QString site;
};

class ISearchable
{
public:
    virtual QList<Result> search(const QString &query) = 0;
};

class SiteA : public ISearchable
{
public:
    QList<Result> search(const QString &query) Q_DECL_OVERRIDE
    {
        QList<Result> results;
        QThread::sleep(1);
        Result example;
        example.text = "This is an example of search from SiteA";
        example.site = "sitea";

        results << example;
        return results;
    }
};

class SiteB : public ISearchable
{
public:
    QList<Result> search(const QString &query) Q_DECL_OVERRIDE
    {
        QList<Result> results;
        QThread::sleep(1);
        Result example;
        example.text = "This is an example of search from SiteB";
        example.site = "siteb";
        results << example;
        return results;
    }
};
QList<Result> runSearch(const QString &query, ISearchable* site){return site->search(query);}
int main(int argc, char *argv[])
{
    QApplication application(argc, argv);

    QMap<QString, ISearchable *> container;

    container.insert("sitea", new SiteA);
    container.insert("siteb", new SiteB);
    QWidget mainWid;
    QGridLayout* mainLay= new QGridLayout(&mainWid);
    QStandardItemModel* baseModel = new QStandardItemModel(&mainWid);
    baseModel->insertColumn(0);
    QListView* resultList =new QListView(&mainWid);
    QLineEdit* queryEdit= new QLineEdit(&mainWid);
    QPushButton* searchBtn = new QPushButton(QStringLiteral("Search"),&mainWid);
    resultList->setModel(baseModel);
    mainLay->addWidget(queryEdit,0,0);
    mainLay->addWidget(searchBtn ,0,1);
    mainLay->addWidget(resultList ,1,0,1,2);
    using FutureTemplateArg = QList<Result>;
    QObject::connect(searchBtn ,&QPushButton::clicked,&mainWid,[baseModel,searchBtn ,queryEdit,&container]()->void{
        baseModel->removeRows(0,baseModel->rowCount());
        searchBtn->setEnabled(false);
        queryEdit->setEnabled(false);
        auto futWatch = new QFutureWatcher<FutureTemplateArg>(baseModel);
        QObject::connect(futWatch,&QFutureWatcher<FutureTemplateArg>::finished,searchBtn,[searchBtn ,queryEdit](){
            searchBtn->setEnabled(true);
            queryEdit->setEnabled(true);
        });
        QObject::connect(futWatch,&QFutureWatcher<FutureTemplateArg>::finished,baseModel,[futWatch,baseModel](){
            const FutureTemplateArg singleRes = futWatch->result();
            const int resSize = singleRes.size();
            if(resSize==0)
                return;
            const int startRow = baseModel->rowCount();
            baseModel->insertRows(startRow,resSize);
            for(int i=0;i<resSize;++i )
                baseModel->setData(baseModel->index(i+startRow,0),singleRes.at(i).site + " - " + singleRes.at(i).text);
        });
        QObject::connect(futWatch,&QFutureWatcher<FutureTemplateArg>::finished,futWatch,&QObject::deleteLater);
        QFuture<FutureTemplateArg> calcResult = QtConcurrent::mappedReduced<FutureTemplateArg>(
            container
            , std::bind(runSearch,queryEdit->text(),std::placeholders::_1)
            , [](FutureTemplateArg& collection,const FutureTemplateArg& newRes){collection<<newRes;}
        );
        futWatch->setFuture(calcResult);
    });
    mainWid.show();
    return application.exec();
}