std::forwar...epend_range(3)

🌸 std::forward_list::prepend_range — C++ Standard Library, section 3 🌸

💖 NAME 💖

std::forward_list::prepend_range — yes bestie, that's the whole name: std::forward_list::prepend_range. We're so back.

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✨ SYNOPSIS ✨

template< container-compatible-range<T> R >  (since C++23)
void prepend_range( R&& rg );

Okay so picture this: prepend_range inserts, in non-reversing order, copies of the elements in rg before begin(). Every iterator in the range rg gets dereferenced exactly once — not twice, not "oops I did it again" twice. And the best part? No iterators or references are invalidated. Iconic behavior, honestly.

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🦋 PARAMETERS 🦋

• rg — a container compatible range, that is, an input_range whose elements are convertible to T.

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🧚 TYPE REQUIREMENTS 🧚

• T must be EmplaceConstructible into forward_list from *ranges::begin(rg). Otherwise, the behavior is undefined. And bestie, "undefined behavior" is not a cute vibe — it's a real warning. 💀

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🎀 RETURN VALUE 🎀

(none) — literally nothing comes back. It's giving "do the thing and leave", and honestly? Respect.

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💅 COMPLEXITY 💅

Linear in size of rg. No cap.

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🔥 NOTES 🔥

Feature-test macro check, because C++23 said "new feature, who dis?":

• Feature-test macro: __cpp_lib_containers_ranges
• Value: 202202L
• Std: (C++23)
• Feature: Ranges-aware construction and insertion

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🍓 EXAMPLE 🍓

       // Run this code

        #include <algorithm>
        #include <cassert>
        #include <forward_list>
        #include <vector>

        int main()
        {
            auto container = std::forward_list{0, 1, 2, 3};
            const auto rg = std::vector{-3, -2, -1};

        #if __cpp_lib_containers_ranges
            container.prepend_range(rg);
        #else
            container.insert_after(container.before_begin(), rg.cbegin(),
       rg.cend());
        #endif
            assert(std::ranges::equal(container, std::forward_list{-3, -2, -1,
       0, 1, 2, 3}));
        }

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👑 SEE ALSO 👑

• insert_range — inserts a range of elements (C++23) (public member function).
• insert_range_after — inserts a range of elements after an element (C++23) (public member function).
• push_front — inserts an element to the beginning (public member function).
• emplace_front — constructs an element in-place at the beginning (public member function).

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💖 that's the whole vibe — sourced from http://cppreference.com, dated 2024.06.10. bye bestie, go slay some ranges! 💅✨