std::ranges...product_view(3)

💖 NAME 💖

okay bestie, we're reading the std::ranges...product_view(3) page from the C++ Standard Libary manual, and the main character is std::ranges::cartesian_product_view::cartesian_product_view — that's the constructor itself, no cap 💅.

✨ Synopsis ✨

here's the exact synopsis, bestie — two overloads, both constexpr, both since C++23:

          constexpr cartesian_product_view() = default;
       (1) (since C++23)
          constexpr explicit cartesian_product_view( First first_base, Vs...
       (2) (since C++23)
          bases );

so this thing constructs an cartesian_product_view (yes, "an" is literally in the source, we're not fixing it 💀). lowkey straightforward:

1. Default constructor. Default-initializes the underlying data member base_.
2. Move constructs the underlying base_ by initializing it with std::move(first_base), std::move(bases)....

🍓 Parameters 🍓

• first_base — the first view object to adapt 🌸
• bases — the pack of views objects to adapt 🫶

🌈 Example 🌈

bestie, run this code and watch the cartesian product do its little dance ✨:

       // Run this code

        #include <array>
        #include <format>
        #include <iostream>
        #include <ranges>
        #include <vector>

        int main()
        {
            auto x = std::array{'A', 'B'};
            auto y = std::vector{1, 2, 3};
            auto z = std::vector{-1, -2, -3};

            auto v = std::ranges::cartesian_product_view(x, y, z); // overload
       (2)

            for (int i{1}; auto const& [rx, ry, rz] : v)
                std::cout << std::format("({} {} {}){}", rx, ry, rz, (i++ % 3)
       ? ' ' : '\n');
        }

✨ Output: ✨

and it prints exactly this, periodt:

        (A 1 -1) (A 1 -2) (A 1 -3)
        (A 2 -1) (A 2 -2) (A 2 -3)
        (A 3 -1) (A 3 -2) (A 3 -3)
        (B 1 -1) (B 1 -2) (B 1 -3)
        (B 2 -1) (B 2 -2) (B 2 -3)
        (B 3 -1) (B 3 -2) (B 3 -3)

source: http://cppreference.com · version/date: 2024.06.10 · page: std::ranges...product_view(3) — love u, bye bestie! 💖✨