std::deque::append_range(3)

🎀 std::deque::append_range(3) 🎀

okay so this is the C++ Standard Libary manual page for std::deque::append_range, and bestie, it's giving C++23 range-insertion era ✨.

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🌸 NAME 🌸

std::deque::append_range — and the NAME line is literally std::deque::append_range - std::deque::append_range, no cap 😭.

✨ Synopsis ✨

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

It inserts copies of elements from the range rg before end(), in non-reversing order 💅.

All iterators (including the end() iterator) are invalidated. No references are invalidated.

Each iterator in rg is dereferenced exactly once. Slay, efficient little range.

💖 Parameters 💖

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

🦋 Type requirements 🦋

• T must be EmplaceConstructible into deque from *ranges::begin(rg). Otherwise, the behavior is undefined.

🚨 undefined behavior alert, bestie — this is not a vibe you want to f around with.

🌈 Return value 🌈

(none) — literally nothing, she just does the insertion and leaves 👑.

🔥 Complexity 🔥

Linear in size of rg 🔥. The number of calls to the constructor of T is exactly equal to the std::ranges::size(rg)).

💀 Exceptions 💀

• If an exception is thrown other than by the copy constructor, move constructor, assignment operator, or move assignment operator of T, there are no effects.
• If an exception is thrown while inserting a single element at either end, there are no effects.
• Otherwise, if an exception is thrown by the move constructor of a non-CopyInsertable T, the effects are unspecified.

💀 “unspecified” is doing a lot of heavy lifting there — keep that caveat in mind.

📝 Notes 📝

• __cpp_lib_containers_ranges — value 202202L, std C++23, feature: Ranges-aware construction and insertion ✨.

🧚 Example 🧚

// Run this code

#include <algorithm>
#include <cassert>
#include <deque>
#include <list>

int main()
{
    auto head = std::deque{1, 2, 3, 4};
    const auto tail = std::list{-5, -6, -7};
#ifdef __cpp_lib_containers_ranges
    head.append_range(tail);
#else
    head.insert(head.end(), tail.cbegin(), tail.cend());
#endif
    assert(std::ranges::equal(head, std::deque{1, 2, 3, 4, -5, -6, -7}));
}

👑 See also 👑

• prepend_range — adds a range of elements to the beginning (C++23) (public member function)
• insert_range — inserts a range of elements (C++23) (public member function)
• push_back — adds an element to the end (public member function)
• emplace_back — constructs an element in-place at the end (C++11) (public member function)

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mwah 💋 — source: http://cppreference.com, version/date: 2024.06.10 🫶