C++ React Events Examples -立哥開發

// Distributed under Jacky Zong License, Version 2.0.
// (See accompanying file LICENSE_2_0.txt or copy at

#include
#include
#include

#include “react/Event.h”
#include “react/Observer.h”

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 1 - Hello world
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example1
{
using namespace std;
using namespace react;

Group group;

// An event source that emits values of type string
namespace v1
{
    EventSource<string> mySource = EventSource<string>::Create(group);

    void Run()
    {
        cout << "Example 1 - Hello world (string source)" << endl;

        auto obs = Observer::Create([] (const auto& events)
            {
                for (const auto& e : events)
                    cout << e << std::endl;
            }, mySource);

        mySource << string("Hello world #1");

        // Or without the operator:
        mySource.Emit(string("Hello world #2"));

        cout << endl;
    }
}

// An event source without an explicit value type
namespace v2
{
    EventSource<> helloWorldTrigger = EventSource<>::Create(group);

    void Run()
    {
        cout << "Example 1 - Hello world (token source)" << endl;

        int count = 0;

        auto obs = Observer::Create([&] (const auto& events)
            {
                for (auto t : events)
                    cout << "Hello world #" << ++count << endl;
            }, helloWorldTrigger);

        helloWorldTrigger.Emit();

        // Or without the stream operator:
        helloWorldTrigger << Token::value;

        cout << endl;
    }
}

}

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 2 - Merging event streams
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example2
{
using namespace std;
using namespace react;

Group group;

// An event stream that merges both sources
EventSource<> leftClick = EventSource<>::Create(group);
EventSource<> rightClick = EventSource<>::Create(group);

Event<> anyClick = Merge(leftClick, rightClick);

void Run()
{
    cout << "Example 2 - Merging event streams (Merge)" << endl;

    int count = 0;

    auto obs = Observer::Create([&] (const auto& events)
        {
            for (auto t : events)
                cout << "clicked #" << ++count << endl;
        }, anyClick);

    leftClick.Emit();  // output: clicked #1 
    rightClick.Emit(); // output: clicked #2

    cout << endl;
}

}

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 3 - Filtering events
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example3
{
using namespace std;
using namespace react;

Group group;

EventSource<int> numbers = EventSource<int>::Create(group);

Event<int> greater10 = Filter([] (int n) { return n > 10; }, numbers);

void Run()
{
    cout << "Example 3 - Filtering events" << endl;

    auto obs = Observer::Create([&] (const auto& events)
        {
            for (auto n : events)
                cout << n << endl;
        }, greater10);

    numbers << 5 << 11 << 7 << 100; // output: 11, 100

    cout << endl;
}

}

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 4 - Filtering events
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example4
{
using namespace std;
using namespace react;

Group group;

// Data types
enum class Tag { normal, critical };
using TaggedNum = pair<Tag, int>;

EventSource<int> numbers = EventSource<int>::Create(group);

Event<TaggedNum> tagged = Transform<TaggedNum>([] (int n)
    {
        if (n > 10)
            return TaggedNum( Tag::critical, n );
        else
            return TaggedNum( Tag::normal, n );
    }, numbers);

void Run()
{
    cout << "Example 4 - Transforming  events" << endl;

    auto obs = Observer::Create([] (const auto& events)
        {
            for (TaggedNum e : events)
            {
                if (e.first == Tag::critical)
                    cout << "(critical) " << e.second << endl;
                else
                    cout << "(normal)  " << e.second << endl;
            }
        }, tagged);

    numbers << 5;   // output: (normal) 5
    numbers << 20;  // output: (critical) 20

    cout << endl;
}

}

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 5 - Queuing multiple inputs
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example5
{
using namespace std;
using namespace react;

Group group;

EventSource<int> src = EventSource<int>::Create(group);

void Run()
{
    cout << "Example 5 - Queuing multiple inputs" << endl;

    auto obs = Observer::Create([] (const auto& events)
        {
            for (int e : events)
                cout << e << endl;
        }, src);
    // output: 1, 2, 3, 4

    group.DoTransaction([]
        {
            src << 1 << 2 << 3;
            src << 4;
        });

    cout << endl;
}

}

///////////////////////////////////////////////////////////////////////////////////////////////////
/// Run examples
///////////////////////////////////////////////////////////////////////////////////////////////////
int main()
{
example1::v1::Run();
example1::v2::Run();
example2::Run();
example3::Run();
example4::Run();
example5::Run();

return 0;

}