https://github.com/pavelkryukov/forward_list2

C++ std::forward_list with push_back and before_end
https://github.com/pavelkryukov/forward_list2

boost cpp23 cpp26 forward-list linked-list linked-list-in-cpp linked-lists stl stl-containers

Last synced: about 20 hours ago
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C++ std::forward_list with push_back and before_end

• Host: GitHub
• URL: https://github.com/pavelkryukov/forward_list2
• Owner: pavelkryukov
• License: mit
• Created: 2021-12-10T20:56:50.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2022-06-18T11:52:44.000Z (over 2 years ago)
• Last Synced: 2023-02-28T18:19:20.113Z (over 1 year ago)
• Topics: boost, cpp23, cpp26, forward-list, linked-list, linked-list-in-cpp, linked-lists, stl, stl-containers
• Language: C++
• Homepage: https://pavelkryukov.github.io/forward_list2/
• Size: 132 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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# forward_list2

Wrapper around C++ [`std::forward_list`](https://en.cppreference.com/w/cpp/container/forward_list) which adds an iterator to the last element.

The idea has been proposed and discussed here: [cpp-ru/ideas#487](https://github.com/cpp-ru/ideas/issues/487).

### Extra functions

```c++

const_reference back() const;

const_iterator before_end() const noexcept;

const_iterator cbefore_end() const noexcept;

void push_back(const T& value);

void push_back(T&& value);

template

reference emplace_back(Args&&... args);

```

### Price

* Compute time overheads to maintain the iterator to the last element.

* Extra O(N) traversals on copy assignment and sorting.

* Memory size overhead on empty container:

```c++

static_assert(sizeof(std::forward_list) == sizeof(void*));

static_assert(sizeof(forward_list2) == 2 * sizeof(void*));

```

### Limitations

* No `reference back();` is available since it would require passing non-constant iterator to `erase_after`.

### Impact

* Identified and fixed [PR libstdc++/103853](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103853).