cib demo: Range v3 comprehensions example

main.cpp

// Range v3 library
//
//  Copyright Eric Niebler 2013-present
//
//  Use, modification and distribution is subject to 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)
//
// Project home: https://github.com/ericniebler/range-v3
//

// cib:{"fetch":"https://cdn.rawgit.com/tbfleming/cib-zips/816dc978/range-v3-0.3.0.zip", "system_includes":["range-v3-0.3.0/include"], "unzip_compiler":true}

#include <iostream>
#include <range/v3/all.hpp>

using namespace ranges;

int main()
{
    // Define an infinite range containing all the Pythagorean triples:
    auto triples =
        view::for_each(view::ints(1), [](int z)
        {
            return view::for_each(view::ints(1, z+1), [=](int x)
            {
                return view::for_each(view::ints(x, z+1), [=](int y)
                {
                    return yield_if(x*x + y*y == z*z, std::make_tuple(x, y, z));
                });
            });
        });

    //// This alternate syntax also works:
    //auto triples = view::ints(1)      >>= [] (int z) { return
    //               view::ints(1, z+1) >>= [=](int x) { return
    //               view::ints(x, z+1) >>= [=](int y) { return
    //   yield_if(x*x + y*y == z*z,
    //       std::make_tuple(x, y, z)); };}; };

    // Display the first 100 triples
    RANGES_FOR(auto triple, triples | view::take(100))
    {
        std::cout << '('
            << std::get<0>(triple) << ','
            << std::get<1>(triple) << ','
            << std::get<2>(triple) << ')' << '\n';
    }
}