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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
/*!
\example wordcount
\meta tags {threads, console}
\title Word Count
\ingroup qtconcurrentexamples
\examplecategory {Data Processing & I/O}
\brief Demonstrates how to use the map-reduce algorithm.
The Qt Concurrent \e {Word Count} example demonstrates the use of the
map-reduce algorithm when applied to the problem of counting words in a
collection of files.
First, the Application starts a QFileDialog to select a starting
path, and then prints the output to the console.
\include examples-run.qdocinc
\section1 Comparing the operations
Compare a single-threaded, sequential approach to counting the words in
the text files to a multithreaded approach with mappedReduced():
\dots
\snippet wordcount/main.cpp 1
\dots
\snippet wordcount/main.cpp 2
\dots
The first argument to the \l {QtConcurrent::}{mappedReduced} function is the
container to operate on. The second argument is the mapping function
\c {countWords()}. It is called in parallel by multiple threads. The
third argument is the reducing function \c {reduce()}. It is called
once for each result returned by the mapping function, and generates the
final computation result.
The function returns a QFuture object of type \c WordCount. Call the
\l {QFuture::}{result} function immediately on this QFuture to block further
execution until the result becomes available.
\note The mapping function must be thread-safe since it is called from
multiple threads.
*/
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