虚函数与bind对比测试

#include <iostream>
#include <functional>
#include <benchmark/benchmark.h>
class Calculator {
public:
    virtual int calculate(int x, int y) = 0;
};
class Minus : public Calculator {
public:
    virtual int calculate(int x, int y) override {
        return x + y;
    }
};
class Plus  : public Calculator {
public:
    virtual int calculate(int x, int y) override {
        return x - y;
    }
};
class CalculatorClient {
public:
    CalculatorClient(Calculator *p) : client_(p) {
    }
public:
    int calculate(int x, int y) {
        return client_->calculate(x, y);
    }
private:
    Calculator *client_ = nullptr;
};
class BindCalculatorClient {
public:
    BindCalculatorClient(std::function<int(int, int)>&&func) : func_(std::move(func)) {
    }
public:
    int calculate(int x, int y) {
        return func_(x, y);
    }
private:
    std::function<int(int, int)>func_;
};

static void BM_TestVirtualFunction(benchmark::State &state) {
    Minus minus;
    CalculatorClient client0(&minus);

    Plus plus;
    CalculatorClient client1(&plus);

    for (auto _ : state) {
        client0.calculate(1, 2);
        client1.calculate(1, 2);
    }
}
static void BM_TestBindFunction(benchmark::State &state) {
    Minus minus;
    BindCalculatorClient client0(std::bind(&Minus::calculate, minus, std::placeholders::_1, std::placeholders::_2));

    Plus plus;
    BindCalculatorClient client1(std::bind(&Plus::calculate, plus, std::placeholders::_1, std::placeholders::_2));

    for (auto _ : state) {
        client0.calculate(1, 2);
        client1.calculate(1, 2);
    }
}

BENCHMARK(BM_TestVirtualFunction)->Iterations(100000000);
BENCHMARK(BM_TestBindFunction)->Iterations(100000000);
BENCHMARK_MAIN();