cpp.react/examples/src/BasicAlgorithms.cpp at master · zengyuxing007/cpp.react · GitHub

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// Copyright Sebastian Jeckel 2014.

// Distributed under the Boost Software License, Version 1.0.

// (See accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

#include <iostream>

#include <string>

#include <utility>

#include <vector>

#include "react/Domain.h"

#include "react/Signal.h"

#include "react/Event.h"

#include "react/Observer.h"

#include "react/Algorithm.h"

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 1 - Converting events to signals

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example1

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

class Sensor

{

public:

USING_REACTIVE_DOMAIN(D)

EventSourceT<int> Samples = MakeEventSource<D,int>();

SignalT<int> LastSample = Hold(Samples, 0);

};

void Run()

{

cout << "Example 1 - Converting events to signals" << endl;

Sensor mySensor;

Observe(mySensor.LastSample, [] (int v) {

std::cout << v << std::endl;

});

mySensor.Samples << 20 << 21 << 21 << 22; // output: 20, 21, 22

DoTransaction<D>([&] {

mySensor.Samples << 30 << 31 << 31 << 32;

}); // output: 32

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 2 - Converting signals to events

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example2

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

class Employee

{

public:

USING_REACTIVE_DOMAIN(D)

VarSignalT<string> Name = MakeVar<D>(string( "Bob" ));

VarSignalT<int> Salary = MakeVar<D>(3000);

EventsT<int> SalaryChanged = Monitor(Salary);

};

void Run()

{

cout << "Example 2 - Converting signals to events" << endl;

Employee bob;

Observe(

bob.SalaryChanged,

With(bob.Name),

[] (int newSalary, const string& name) {

cout << name << " now earns " << newSalary << endl;

});

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 3 - Folding event streams into signals (1)

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example3

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

class Counter

{

public:

USING_REACTIVE_DOMAIN(D)

EventSourceT<> Increment = MakeEventSource<D>();

SignalT<int> Count = Iterate(

Increment,

[] (Token, int oldCount) {

return oldCount + 1;

});

};

void Run()

{

cout << "Example 3 - Folding event streams into signals (1)" << endl;

Counter myCounter;

// Note: Using function-style operator() instead of .Emit() and .Value()

myCounter.Increment();

cout << myCounter.Count() << endl; // output: 3

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 4 - Folding event streams into signals (2)

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example4

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

class Sensor

{

public:

USING_REACTIVE_DOMAIN(D)

EventSourceT<float> Input = MakeEventSource<D,float>();

SignalT<int> Count = Iterate(

Tokenize(Input),

[] (Token, int oldCount) {

return oldCount + 1;

});

SignalT<float> Sum = Iterate(

Input,

0.0f,

[] (float v, float sum) {

return v + sum;

});

SignalT<float> Average = MakeSignal(

With(Sum,Count),

[] (float sum, int count) {

return count != 0 ? sum / count : 0.0f;

});

};

void Run()

{

cout << "Example 4 - Folding event streams into signals (2)" << endl;

Sensor mySensor;

mySensor.Input << 10.0f << 5.0f << 10.0f << 8.0f;

cout << "Average: " << mySensor.Average() << endl; // output: 8.25

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 5 - Folding event streams into signals (3)

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example5

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

enum ECmd { increment, decrement, reset };

class Counter

{

public:

USING_REACTIVE_DOMAIN(D)

EventSourceT<int> Update = MakeEventSource<D,int>();

VarSignalT<int> Delta = MakeVar<D>(1);

VarSignalT<int> Start = MakeVar<D>(0);

SignalT<int> Count = Iterate(

Update,

Start.Value(),

With(Delta, Start),

[] (int cmd, int oldCount, int delta, int start) {

if (cmd == increment)

return oldCount + delta;

else if (cmd == decrement)

return oldCount - delta;

else

return start;

});

};

void Run()

{

cout << "Example 5 - Folding event streams into signals (3)" << endl;

Counter myCounter;

cout << "Start: " << myCounter.Count() << endl; // output: 0

myCounter.Update(increment);

cout << "3x increment by 1: " << myCounter.Count() << endl; // output: 3

myCounter.Delta <<= 5;

myCounter.Update(decrement);

cout << "1x decrement by 5: " << myCounter.Count() << endl; // output: -2

myCounter.Start <<= 100;

myCounter.Update(reset);

cout << "reset to 100: " << myCounter.Count() << endl; // output: 100

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Example 6 - Avoiding expensive copies

///////////////////////////////////////////////////////////////////////////////////////////////////

namespace example6

{

using namespace std;

using namespace react;

REACTIVE_DOMAIN(D, sequential)

class Sensor

{

public:

USING_REACTIVE_DOMAIN(D)

EventSourceT<int> Input = MakeEventSource<D,int>();

VarSignalT<int> Threshold = MakeVar<D>(42);

SignalT<vector<int>> AllSamples = Iterate(

Input,

vector<int>{},

[] (int input, vector<int>& all) {

all.push_back(input);

});

SignalT<vector<int>> CriticalSamples = Iterate(

Input,

vector<int>{},

With(Threshold),

[] (int input, vector<int>& critical, int threshold) {

if (input > threshold)

critical.push_back(input);

});

};

void Run()

{

cout << "Example 6 - Avoiding expensive copies" << endl;

Sensor mySensor;

mySensor.Input << 40 << 29 << 43 << 50;

cout << "All samples: ";

for (auto const& v : mySensor.AllSamples())

cout << v << " ";

cout << endl;

cout << "Critical samples: ";

for (auto const& v : mySensor.CriticalSamples())

cout << v << " ";

cout << endl;

}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Run examples

///////////////////////////////////////////////////////////////////////////////////////////////////

int main()

{

example1::Run();

example2::Run();

example3::Run();

example4::Run();

example5::Run();

example6::Run();

return 0;

}

cpp.react/examples/src/BasicAlgorithms.cpp at master · zengyuxing007/cpp.react · GitHub

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