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The Reactive Extensions for C++ (RxCpp) is a library of algorithms for values-distributed-in-time. The Range-v3 library does the same for values-distributed-in-space.

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Documentation rxcpp doxygen documentation
reactivex intro rx marble diagrams


RxCpp is a header-only C++ library that only depends on the standard library. The CMake build generates documentation and unit tests. The unit tests depend on a git submodule for the Catch library.


Add Rx/v2/src to the include paths

lines from bytes

#include "rxcpp/rx.hpp"
namespace Rx {
using namespace rxcpp;
using namespace rxcpp::sources;
using namespace rxcpp::operators;
using namespace rxcpp::util;
using namespace Rx;

#include <regex>
#include <random>
using namespace std;
using namespace std::chrono;

int main()
    random_device rd;   // non-deterministic generator
    mt19937 gen(rd());
    uniform_int_distribution<> dist(4, 18);

    // for testing purposes, produce byte stream that from lines of text
    auto bytes = range(0, 10) |
        flat_map([&](int i){
            auto body = from((uint8_t)('A' + i)) |
                repeat(dist(gen)) |
            auto delim = from((uint8_t)'\r');
            return from(body, delim) | concat();
        }) |
        window(17) |
        flat_map([](observable<uint8_t> w){
            return w |
                    [](vector<uint8_t> v, uint8_t b){
                        return v;
                    }) |
        }) |
        tap([](const vector<uint8_t>& v){
            // print input packet of bytes
            copy(v.begin(), v.end(), ostream_iterator<long>(cout, " "));
            cout << endl;

    // recover lines of text from byte stream
    auto removespaces = [](string s){
        s.erase(remove_if(s.begin(), s.end(), ::isspace), s.end());
        return s;

    // create strings split on \r
    auto strings = bytes |
        concat_map([](vector<uint8_t> v){
            string s(v.begin(), v.end());
            regex delim(R"/(\r)/");
            cregex_token_iterator cursor(&s[0], &s[0] + s.size(), delim, {-1, 0});
            cregex_token_iterator end;
            vector<string> splits(cursor, end);
            return iterate(move(splits));
        }) |
        filter([](const string& s){
            return !s.empty();
        }) |
        publish() |

    // filter to last string in each line
    auto closes = strings |
            [](const string& s){
                return s.back() == '\r';
            }) |
        Rx::map([](const string&){return 0;});

    // group strings by line
    auto linewindows = strings |
        window_toggle(closes | start_with(0), [=](int){return closes;});

    // reduce the strings for a line into one string
    auto lines = linewindows |
        flat_map([&](observable<string> w) {
            return w | start_with<string>("") | sum() | Rx::map(removespaces);

    // print result
    lines |

    return 0;

Reactive Extensions

The ReactiveX Observable model allows you to treat streams of asynchronous events with the same sort of simple, composable operations that you use for collections of data items like arrays. It frees you from tangled webs of callbacks, and thereby makes your code more readable and less prone to bugs.


Other language implementations


Cloning RxCpp

RxCpp uses a git submodule (in ext/catch) for the excellent Catch library. The easiest way to ensure that the submodules are included in the clone is to add --recursive in the clone command.

git clone --recursive
cd RxCpp


To install RxCpp into your OS you need to follow standart procedure:

mkdir build
cd build
cmake ..
make install 

If you're using the vcpkg dependency manager, you can install RxCpp using a single one-line command:

vcpkg install rxcpp

Vcpkg will acquire RxCpp, build it from source in your computer, and provide CMake integration support for your projects.

See the vcpkg repository for more information.


After you have successfully installed RxCpp you can import it into any project by simply adding to your CMakeLists.txt:

find_package(rxcpp CONFIG)

Building RxCpp Unit Tests

  • RxCpp is regularly tested on OSX and Windows.
  • RxCpp is regularly built with Clang, Gcc and VC
  • RxCpp depends on the latest compiler releases.

RxCpp uses CMake to create build files for several platforms and IDE's

ide builds


mkdir projects/build
cd projects/build

Visual Studio 2017

mkdir projects\build
cd projects\build
cmake -G "Visual Studio 15" -DRXCPP_DISABLE_TESTS_AND_EXAMPLES=0 ..\CMake\
msbuild Project.sln

makefile builds


mkdir projects/build
cd projects/build
cmake -G"Unix Makefiles" -DCMAKE_BUILD_TYPE=RelWithDebInfo -DRXCPP_DISABLE_TESTS_AND_EXAMPLES=0 -B. ../CMake

Linux --- Clang

mkdir projects/build
cd projects/build

Linux --- GCC

mkdir projects/build
cd projects/build


mkdir projects\build
cd projects\build

The build only produces test and example binaries.

Running tests

  • You can use the CMake test runner ctest
  • You can run the test binaries directly rxcpp_test_*
  • Tests can be selected by name or tag Example of by-tag

rxcpp_test_subscription [perf]


RxCpp uses Doxygen to generate project documentation.

When Doxygen+Graphviz is installed, CMake creates a special build task named doc. It creates actual documentation and puts it to projects/doxygen/html/ folder, which can be published to the gh-pages branch. Each merged pull request will build the docs and publish them.

Developers Material

Contributing Code

Before submitting a feature or substantial code contribution please discuss it with the team and ensure it follows the product roadmap. Note that all code submissions will be rigorously reviewed and tested by the Rx Team, and only those that meet an extremely high bar for both quality and design/roadmap appropriateness will be merged into the source.

Microsoft Open Source Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.