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Copy pathBasicAlgorithms.cpp
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321 lines (248 loc) · 8.22 KB
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// Copyright Sebastian Jeckel 2016.
// 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/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;
ReactiveGroup group;
struct Sensor
{
EventSource<int> samples { group };
Signal<int> lastSample = Hold(0, samples);
};
void Run()
{
cout << "Example 1 - Converting events to signals" << endl;
Sensor mySensor;
Observer obs(
[] (int v)
{
cout << v << endl;
},
mySensor.lastSample);
mySensor.samples << 20 << 21 << 21 << 22; // output: 20, 21, 22
group.DoTransaction([&]
{
mySensor.samples << 30 << 31 << 31 << 32;
}); // output: 32
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 2 - Converting signals to events
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example2
{
using namespace std;
using namespace react;
ReactiveGroup group;
struct Employee
{
VarSignal<string> name { group, string( "Bob" ) };
VarSignal<int> salary { group, 3000 };
};
void Run()
{
cout << "Example 2 - Converting signals to events" << endl;
Employee bob;
Observer obs(
[] (EventRange<int> in, const string& name)
{
for (int newSalary : in)
cout << name << " now earns " << newSalary << endl;
},
Monitor(bob.salary), bob.name);
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 3 - Folding event streams into signals (1)
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example3
{
using namespace std;
using namespace react;
ReactiveGroup group;
struct Counter
{
EventSource<> increment { group };
Signal<int> count = Iterate<int>(
0,
[] (EventRange<> in, int count)
{
for (auto _ : in)
++count;
return count;
},
increment);
};
void Run()
{
cout << "Example 3 - Folding event streams into signals (1)" << endl;
Counter myCounter;
myCounter.increment.Emit();
myCounter.increment.Emit();
myCounter.increment.Emit();
cout << myCounter.count.Value() << endl; // output: 3
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 4 - Folding event streams into signals (2)
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example4
{
using namespace std;
using namespace react;
ReactiveGroup group;
struct Sensor
{
EventSource<float> input{ group };
Signal<int> count = Iterate<int>(
0,
[] (EventRange<float> in, int count)
{
for (auto _ : in)
count++;
return count;
},
input);
Signal<float> sum = Iterate<float>(
0.0f,
[] (EventRange<float> in, float sum)
{
for (auto v : in)
sum += v;
return sum;
},
input);
VarSignal<float> average{ group };
};
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.Value() << endl; // output: 8.25
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 5 - Folding event streams into signals (3)
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example5
{
using namespace std;
using namespace react;
ReactiveGroup group;
enum ECmd { increment, decrement, reset };
class Counter
{
private:
static int DoCounterLoop(EventRange<int> in, int count, int delta, int start)
{
for (int cmd : in)
{
if (cmd == increment)
count += delta;
else if (cmd == decrement)
count -= delta;
else
count = start;
}
return count;
}
public:
EventSource<int> update{ group };
VarSignal<int> delta{ group, 1 };
VarSignal<int> start{ group, 0 };
Signal<int> count{ Iterate<int>(start.Value(), DoCounterLoop, update, delta, start) };
};
void Run()
{
cout << "Example 5 - Folding event streams into signals (3)" << endl;
Counter myCounter;
cout << "Start: " << myCounter.count.Value() << endl; // output: 0
myCounter.update.Emit(increment);
myCounter.update.Emit(increment);
myCounter.update.Emit(increment);
cout << "3x increment by 1: " << myCounter.count.Value() << endl; // output: 3
myCounter.delta <<= 5;
myCounter.update.Emit(decrement);
cout << "1x decrement by 5: " << myCounter.count.Value() << endl; // output: -2
myCounter.start <<= 100;
myCounter.update.Emit(reset);
cout << "reset to 100: " << myCounter.count.Value() << endl; // output: 100
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Example 6 - Avoiding expensive copies
///////////////////////////////////////////////////////////////////////////////////////////////////
namespace example6
{
using namespace std;
using namespace react;
ReactiveGroup group;
class Sensor
{
private:
static void DoIterateAllSamples(EventRange<int> in, vector<int>& all)
{
for (int input : in)
all.push_back(input);
}
static void DoIterateCritSamples(EventRange<int> in, vector<int>& critical, int threshold)
{
for (int input : in)
if (input > threshold)
critical.push_back(input);
}
public:
EventSource<int> input{ group };
VarSignal<int> threshold{ group, 42 };
Signal<vector<int>> allSamples{ Iterate<vector<int>>(vector<int>{ }, DoIterateAllSamples, input) };
Signal<vector<int>> criticalSamples{ Iterate<vector<int>>(vector<int>{ }, DoIterateCritSamples, input, threshold) };
};
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.Value())
cout << v << " ";
cout << endl;
cout << "Critical samples: ";
for (auto const& v : mySensor.criticalSamples.Value())
cout << v << " ";
cout << endl;
cout << endl;
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Run examples
///////////////////////////////////////////////////////////////////////////////////////////////////
int main()
{
example1::Run();
example2::Run();
example3::Run();
example4::Run();
example5::Run();
example6::Run();
return 0;
}