# coroutine

***

**1. Asynchronous File I/O**

```cpp
#include <boost/asio.hpp>
using namespace boost::asio;

io_context io;
ip::tcp::socket socket(io);

boost::asio::async_read(socket, ..., [](error_code ec, std::size_t bytes_transferred) {
    // Handle the read operation
});
```

**2. Network Server**

```cpp
#include <boost/asio.hpp>
using namespace boost::asio;

io_context io;
ip::tcp::acceptor acceptor(io, ip::tcp::endpoint(ip::tcp::v4(), 8080));

acceptor.async_accept([&](error_code ec, ip::tcp::socket socket) {
    // Handle the accepted connection
});
```

**3. Message Queue**

```cpp
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/coroutines/all.hpp>
using namespace boost::coroutines;

cpp_int value = 0;

auto producer = [](context& ctx) {
    while (true) {
        value++;
        ctx.yield();
    }
};

auto consumer = [](context& ctx) {
    while (true) {
        std::cout << value << "\n";
        ctx.yield();
    }
};

// Create and run the coroutines
boost::coroutines::routine p(producer);
boost::coroutines::routine c(consumer);
p.run();
c.run();
```

**4. Stream Processing**

```cpp
#include <boost/iterator/counting_iterator.hpp>
#include <boost/range/join.hpp>
#include <boost/coroutines/all.hpp>
using namespace boost::coroutines;

template<typename Container>
auto wrap_counting(Container& c) {
    return boost::make_iterator_range(
        boost::counting_iterator<int>(0),
        boost::make_reverse_iterator(boost::make_iterator_range(c.rbegin(), c.rend())));
}

auto filter(context& ctx, const std::vector<int>& v) {
    for (int i : v) {
        if (i % 2 == 0) ctx.yield(i);
    }
}

int main() {
    std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    auto r = filter(call_cooperative(), v);
    for (int i : r) {
        std::cout << i << " ";
    }
    std::cout << "\n";
}
```

**5. Game Loop**

```cpp
#include <chrono>
#include <vector>
#include <boost/coroutines/all.hpp>
using namespace boost::coroutines;

struct game_loop_args {
    float dt;
    std::vector<int>& entities;
};

auto game_loop_coroutine(context& ctx, game_loop_args args) {
    while (true) {
        // Update the game state
        for (int& entity : args.entities) entity++;

        // Sleep for the specified dt
        std::chrono::milliseconds dt(static_cast<int>(args.dt * 1000));
        std::this_thread::sleep_for(dt);

        // Yield to the caller
        ctx.yield();
    }
}

int main() {
    std::vector<int> entities = {1, 2, 3, 4, 5};
    constexpr float dt = 0.01f;

    // Create and run the coroutine
    routine<game_loop_args> loop(game_loop_coroutine);
    loop.run({dt, entities});
}
```

**6. Asynchronous Database Access**

```cpp
#include <boost/asio.hpp>
#include <boost/thread.hpp>
using namespace boost;
using namespace boost::asio;
using namespace boost::thread;

io_context io;
mutex m;

void coroutine_thread(promise<int>&& p) {
    io.run();
    p.set_value(0);
}

void start_coroutine() {
    promise<int> p;
    thread t(coroutine_thread, move(p));
    p.get_future().wait();  // Blocks until the coroutine exits
    t.join();
}
```

**7. Asynchronous Logging**

```cpp
#include <boost/asio.hpp>
#include <boost/thread.hpp>
using namespace boost;
using namespace boost::asio;
using namespace boost::thread;

io_context io;
mutex m;

void coroutine_thread(condition_variable& cv, promise<void>&& p) {
    while (true) {
        cv.wait(m);
        io.run();
        m.unlock();
        p.set_value();
        this_thread::yield();
        m.lock();
    }
}

void start_coroutine(condition_variable& cv) {
    promise<void> p;
    thread t(coroutine_thread, ref(cv), move(p));
    p.get_future().wait();  // Blocks until the coroutine exits
    t.join();
}
```

**8. Parallel Processing**

```cpp
#include <boost/thread.hpp>
using namespace boost;

void coroutine_thread(promise<int>&& p) {
    p.set_value(42);
}

void start_coroutine() {
    promise<int> p;
    thread t(coroutine_thread, move(p));
    p.get_future().wait();  // Blocks until the coroutine returns
    t.join();
}
```

**9. GUI Event Loop**

```cpp
#include <boost/thread.hpp>
#include <boost/chrono.hpp>
using namespace boost;

void coroutine_thread() {
    while (true) {
        // Handle events
        this_thread::sleep_for(chrono::milliseconds(10));
    }
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**10. Web Server**

```cpp
#include <boost/asio.hpp>
using namespace boost;

io_context io;
ip::tcp::acceptor acceptor(io, ip::tcp::endpoint(ip::tcp::v4(), 8080));

void coroutine_thread() {
    while (true) {
        ip::tcp::socket socket(io);
        acceptor.accept(socket);
        // Handle the connection
    }
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**11. Asynchronous Web Requests**

```cpp
#include <boost/asio.hpp>
using namespace boost;

io_context io;
ip::tcp::socket socket(io);
ip::tcp::resolver resolver(io);

void coroutine_thread() {
    ip::tcp::resolver::query query("example.com", "http");
    ip::tcp::resolver::iterator it = resolver.resolve(query);
    socket.connect(*it);
    // Send the HTTP request
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**12. Asynchronous File Encryption**

```cpp
#include <boost/asio.hpp>
#include <boost/algorithm/string.hpp>
using namespace boost;

io_context io;
ip::tcp::socket socket(io);
ip::tcp::resolver resolver(io);

void coroutine_thread() {
    ip::tcp::resolver::query query("example.com", "http");
    ip::tcp::resolver::iterator it = resolver.resolve(query);
    socket.connect(*it);
    // Send the file to be encrypted
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**13. Asynchronous Image Processing**

```cpp
#include <boost/asio.hpp>
using namespace boost;

io_context io;
ip::tcp::socket socket(io);
ip::tcp::resolver resolver(io);

void coroutine_thread() {
    ip::tcp::resolver::query query("example.com", "8080");
    ip::tcp::resolver::iterator it = resolver.resolve(query);
    socket.connect(*it);
    // Send the image to be processed
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**14. Asynchronous Video Streaming**

```cpp
#include <boost/asio.hpp>
using namespace boost;

io_context io;
ip::tcp::socket socket(io);
ip::tcp::resolver resolver(io);

void coroutine_thread() {
    ip::tcp::resolver::query query("example.com", "8080");
    ip::tcp::resolver::iterator it = resolver.resolve(query);
    socket.connect(*it);
    // Send the video stream
}

void start_coroutine() {
    thread t(coroutine_thread);
    t.join();
}
```

**15. Asynchronous Audio Processing**

```cpp
#include <boost/asio.hpp>
using namespace boost;

io_context io;
ip::tcp::socket socket(io);
ip::tcp::resolver resolver(io);

void coroutine_thread() {
    ip::tcp::resolver::query query("example.com", "8080");
    ip::tcp::

```