Clojure の ->> の C++ によるイミテーション

rtl.cc

#include <functional>
#include <vector>
#include <string>
#include <iostream>
#include <cassert>

using namespace std;

vector<string> split(const string& sep, const string& in);
string join(const string& sep, const vector<string>& in);

template <class Out, class D, class F>
Out chain(D data, F f)
{
    return f(data);
}

template <class Out, class D, class F, class... G>
Out chain(D data, F f, G... rest)
{
    return chain<Out>(f(data), rest...);
}

int main()
{
    using namespace std::placeholders;

    string out1 = join("_", split(",", "a,b,c"));
    assert(out1 == "a_b_c");

    string out2 = chain<string>("a,b,c", bind(split, ",", _1), bind(join, "_", _1));
    assert(out2 == out1);
}