cpp's pipe operator

forward.cc

#include <gtest/gtest.h>

template<typename T>
struct Wrapper {
    explicit Wrapper(T value) : value(value) {};
    operator T() {return value;}
    T value;
};

template<typename T>
Wrapper<T> FORWARD(T x)
{
    return Wrapper<T>(x);
}

template<typename T>
T operator>>(Wrapper<T> arg, T(*foo)(T))
{
    return foo(arg.value);
}

template<typename T>
Wrapper<T> operator>>(Wrapper<T> arg, Wrapper<T(*)(T)> foo)
{
    return Wrapper<T>((*foo.value)(arg.value));
}

int add(int x)
{
    return x + 4;
}

int multiply(int x)
{
    return x * 7;
}


TEST(ChainCallTestSuite, ChainCallTestCase) {
    int ret = FORWARD(add(2)) >> FORWARD(multiply);
    ASSERT_EQ(ret, 42);

    int ret_3 = FORWARD(add(2)) >> FORWARD(multiply) >> FORWARD(add);
    ASSERT_EQ(ret_3, 46);
}