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++ // Copyright (C) 2023 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
++
++ #include <QtWidgets/qfiledialog.h>
++ #include <QtWidgets/qapplication.h>
++ #include <QtCore/qdebug.h>
++ #include <QtCore/qmimedatabase.h>
++ #include <QtCore/qelapsedtimer.h>
++ #include <QtConcurrent/qtconcurrentmap.h>
++ #include <QtCore/qtextstream.h>
++
++ typedef QMap<QString, int> WordCount;
++
++ void printHighestResult(const WordCount &, qsizetype);
++ QStringList findFiles(const QString &);
++
++ // Single threaded word counter function.
++ WordCount singleThreadedWordCount(const QStringList &files)
++ {
++ WordCount wordCount;
++ for (const QString &file : files) {
++ QFile f(file);
++ if (!f.open(QIODevice::ReadOnly)) {
++ qWarning().noquote() << "Failed to open file:" << QDir::toNativeSeparators(file)
++ << ":" << f.errorString();
++ return {};
++ }
++ QTextStream textStream(&f);
++ while (!textStream.atEnd()) {
++ const auto words = textStream.readLine().split(' ', Qt::SkipEmptyParts);
++ for (const QString &word : words)
++ wordCount[word] += 1;
++ }
++ }
++ return wordCount;
++ }
++
++ // countWords counts the words in a single file. This function is
++ // called in parallel by several threads and must be thread
++ // safe.
++ WordCount countWords(const QString &file)
++ {
++ QFile f(file);
++ if (!f.open(QIODevice::ReadOnly)) {
++ qWarning().noquote() << "Failed to open file:" << QDir::toNativeSeparators(file)
++ << ":" << f.errorString();
++ return {};
++ }
++ QTextStream textStream(&f);
++ WordCount wordCount;
++
++ while (!textStream.atEnd()) {
++ const auto words = textStream.readLine().split(' ', Qt::SkipEmptyParts);
++ for (const QString &word : words)
++ wordCount[word] += 1;
++ }
++
++ return wordCount;
++ }
++
++ // reduce adds the results from map to the final
++ // result. This functor will only be called by one thread
++ // at a time.
++ void reduce(WordCount &result, const WordCount &w)
++ {
++ for (auto i = w.begin(), end = w.end(); i != end; ++i)
++ result[i.key()] += i.value();
++ }
++
++ int main(int argc, char** argv)
++ {
++ QApplication app(argc, argv);
++ app.setOrganizationName("QtProject");
++ app.setApplicationName(QCoreApplication::translate("main", "Word Count"));
++
++ QFileDialog fileDialog;
++ fileDialog.setOption(QFileDialog::ReadOnly);
++ // Grab the directory path from the dialog
++ auto dirPath = QFileDialog::getExistingDirectory(nullptr,
++ QCoreApplication::translate("main","Select a Folder"),
++ QDir::currentPath());
++
++ QStringList files = findFiles(dirPath);
++ qDebug() << QCoreApplication::translate("main", "Indexing %1 files in %2")
++ .arg(files.size()).arg(dirPath);
++
++ // Start the single threaded operation
++ qint64 singleThreadTime;
++ {
++ QElapsedTimer timer;
++ timer.start();
++ //! [1]
++ WordCount total = singleThreadedWordCount(files);
++ //! [1]
++ singleThreadTime = timer.elapsed();
++ qDebug() << QCoreApplication::translate("main", "Single threaded scanning took %1 ms")
++ .arg(singleThreadTime);
++ }
++ // Start the multithreaded mappedReduced operation.
++ qint64 mapReduceTime;
++ {
++ QElapsedTimer timer;
++ timer.start();
++ //! [2]
++ WordCount total = QtConcurrent::mappedReduced(files, countWords, reduce).result();
++ //! [2]
++ mapReduceTime = timer.elapsed();
++ qDebug() << QCoreApplication::translate("main", "MapReduce scanning took %1 ms")
++ .arg(mapReduceTime);
++ qDebug() << QCoreApplication::translate("main", "MapReduce speedup: %1")
++ .arg(((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1);
++ printHighestResult(total, 10);
++ }
++ }
++
++ // Utility function that recursively searches for text files.
++ QStringList findFiles(const QString &startDir)
++ {
++ QStringList names;
++ QDir dir(startDir);
++ static const QMimeDatabase db;
++
++ const auto files = dir.entryList(QDir::Files);
++ for (const QString &file : files) {
++ const auto path = startDir + QDir::separator() + file;
++ const QMimeType mime = db.mimeTypeForFile(QFileInfo(path));
++ const auto mimeTypesForFile = mime.parentMimeTypes();
++
++ for (const auto &i : mimeTypesForFile) {
++ if (i.contains("text", Qt::CaseInsensitive)
++ || mime.comment().contains("text", Qt::CaseInsensitive)) {
++ names += startDir + QDir::separator() + file;
++ }
++ }
++ }
++
++ const auto subdirs = dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot);
++ for (const QString &subdir : subdirs) {
++ if (names.length() >= 20000) {
++ qDebug() << QCoreApplication::translate("main", "Too many files! Aborting ...");
++ exit(-1);
++ }
++ names += findFiles(startDir + QDir::separator() + subdir);
++ }
++ return names;
++ }
++
++ // Utility function that prints the results of the map in decreasing order based on the value.
++ void printHighestResult(const WordCount &countedWords, qsizetype nResults)
++ {
++ using pair = QPair<QString, int>;
++ QList<pair> vec;
++
++ std::copy(countedWords.keyValueBegin(), countedWords.keyValueEnd(),
++ std::back_inserter<QList<pair>>(vec));
++ std::sort(vec.begin(), vec.end(),
++ [](const pair &l, const pair &r) { return l.second > r.second; });
++
++ qDebug() << QCoreApplication::translate("main", "Most occurring words are:");
++ for (qsizetype i = 0; i < qMin(vec.size(), nResults); ++i)
++ qDebug() << vec[i].first << " : " << vec[i].second;
++ }