range_examples.cpp

// Range demo

#include <iostream>
#include <algorithm>
#include <iterator>

#include <range/v3/all.hpp>

void first_class_range() {
    // Classic STL: A range is just a pair of iterators
    std::vector v1{42, 666, 1, 314 };
    std::sort(v1.begin(), v1.end());
    std::copy(v1.begin(), v1.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";

    // Range STL: A range is a first class entity
    std::vector v2{42, 666, 1, 314 };
    ranges::sort(v2);
    ranges::copy(v2, ranges::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";

}

void composition() {
    std::vector v{1, 2, 3, 4, 5, 6, 7, 8, 9};
    // Lazy function composition: no processing yet
    auto first_5_odd_numbers_squared =
            ranges::view::filter([](int n) { return (n & 1) != 0; }) |
            ranges::view::take(5) |
            ranges::view::transform([](int n) { return n * n; });
    // copy() will pull data out of the pipeline
    ranges::copy(v | first_5_odd_numbers_squared, ranges::ostream_iterator<int>(std::cout, " "));
}

int main() {
    first_class_range();
    composition();
}