[libcxx-commits] [libcxx] [libc++] Implement `std::inplace_vector<T, N>` (PR #105981)

Nikolas Klauser via libcxx-commits libcxx-commits at lists.llvm.org
Fri Nov 8 04:25:00 PST 2024


================
@@ -0,0 +1,1091 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_INPLACE_VECTOR
+#define _LIBCPP_INPLACE_VECTOR
+
+/*
+   inplace_vector synopsis
+
+// mostly freestanding
+#include <compare>              // see [compare.syn]
+#include <initializer_list>     // see [initializer.list.syn]
+
+namespace std {
+  // [inplace.vector], class template inplace_vector
+  template<class T, size_t N>
+  class inplace_vector {        // partially freestanding
+  public:
+    // types:
+    using value_type             = T;
+    using pointer                = T*;
+    using const_pointer          = const T*;
+    using reference              = value_type&;
+    using const_reference        = const value_type&;
+    using size_type              = size_t;
+    using difference_type        = ptrdiff_t;
+    using iterator               = implementation-defined; // see [container.requirements]
+    using const_iterator         = implementation-defined; // see [container.requirements]
+    using reverse_iterator       = std::reverse_iterator<iterator>;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+    // [inplace.vector.cons], construct/copy/destroy
+    constexpr inplace_vector() noexcept;
+    constexpr explicit inplace_vector(size_type n);                         // freestanding-deleted
+    constexpr inplace_vector(size_type n, const T& value);                  // freestanding-deleted
+    template<class InputIterator>
+      constexpr inplace_vector(InputIterator first, InputIterator last);    // freestanding-deleted
+    template<container-compatible-range<T> R>
+      constexpr inplace_vector(from_range_t, R&& rg);                       // freestanding-deleted
+    constexpr inplace_vector(const inplace_vector&);
+    constexpr inplace_vector(inplace_vector&&)
+      noexcept(N == 0 || is_nothrow_move_constructible_v<T>);
+    constexpr inplace_vector(initializer_list<T> il);                       // freestanding-deleted
+    constexpr ~inplace_vector();
+    constexpr inplace_vector& operator=(const inplace_vector& other);
+    constexpr inplace_vector& operator=(inplace_vector&& other)
+      noexcept(N == 0 || (is_nothrow_move_assignable_v<T> &&
+                          is_nothrow_move_constructible_v<T>));
+    constexpr inplace_vector& operator=(initializer_list<T>);               // freestanding-deleted
+    template<class InputIterator>
+      constexpr void assign(InputIterator first, InputIterator last);       // freestanding-deleted
+    template<container-compatible-range<T> R>
+      constexpr void assign_range(R&& rg);                                  // freestanding-deleted
+    constexpr void assign(size_type n, const T& u);                         // freestanding-deleted
+    constexpr void assign(initializer_list<T> il);                          // freestanding-deleted
+
+    // iterators
+    constexpr iterator               begin()         noexcept;
+    constexpr const_iterator         begin()   const noexcept;
+    constexpr iterator               end()           noexcept;
+    constexpr const_iterator         end()     const noexcept;
+    constexpr reverse_iterator       rbegin()        noexcept;
+    constexpr const_reverse_iterator rbegin()  const noexcept;
+    constexpr reverse_iterator       rend()          noexcept;
+    constexpr const_reverse_iterator rend()    const noexcept;
+
+    constexpr const_iterator         cbegin()  const noexcept;
+    constexpr const_iterator         cend()    const noexcept;
+    constexpr const_reverse_iterator crbegin() const noexcept;
+    constexpr const_reverse_iterator crend()   const noexcept;
+
+    // [inplace.vector.capacity] size/capacity
+    constexpr bool empty() const noexcept;
+    constexpr size_type size() const noexcept;
+    static constexpr size_type max_size() noexcept;
+    static constexpr size_type capacity() noexcept;
+    constexpr void resize(size_type sz);                                    // freestanding-deleted
+    constexpr void resize(size_type sz, const T& c);                        // freestanding-deleted
+    static constexpr void reserve(size_type n);                             // freestanding-deleted
+    static constexpr void shrink_to_fit() noexcept;
+
+    // element access
+    constexpr reference       operator[](size_type n);
+    constexpr const_reference operator[](size_type n) const;
+    constexpr reference       at(size_type n);                              // freestanding-deleted
+    constexpr const_reference at(size_type n) const;                        // freestanding-deleted
+    constexpr reference       front();
+    constexpr const_reference front() const;
+    constexpr reference       back();
+    constexpr const_reference back() const;
+
+    // [inplace.vector.data], data access
+    constexpr       T* data()       noexcept;
+    constexpr const T* data() const noexcept;
+
+    // [inplace.vector.modifiers], modifiers
+    template<class... Args>
+      constexpr reference emplace_back(Args&&... args);                     // freestanding-deleted
+    constexpr reference push_back(const T& x);                              // freestanding-deleted
+    constexpr reference push_back(T&& x);                                   // freestanding-deleted
+    template<container-compatible-range<T> R>
+      constexpr void append_range(R&& rg);                                  // freestanding-deleted
+    constexpr void pop_back();
+
+    template<class... Args>
+      constexpr pointer try_emplace_back(Args&&... args);
+    constexpr pointer try_push_back(const T& x);
+    constexpr pointer try_push_back(T&& x);
+    template<container-compatible-range<T> R>
+      constexpr ranges::borrowed_iterator_t<R> try_append_range(R&& rg);
+
+    template<class... Args>
+      constexpr reference unchecked_emplace_back(Args&&... args);
+    constexpr reference unchecked_push_back(const T& x);
+    constexpr reference unchecked_push_back(T&& x);
+
+    template<class... Args>
+      constexpr iterator emplace(const_iterator position, Args&&... args);  // freestanding-deleted
+    constexpr iterator insert(const_iterator position, const T& x);         // freestanding-deleted
+    constexpr iterator insert(const_iterator position, T&& x);              // freestanding-deleted
+    constexpr iterator insert(const_iterator position, size_type n,         // freestanding-deleted
+                              const T& x);
+    template<class InputIterator>
+      constexpr iterator insert(const_iterator position,                    // freestanding-deleted
+                                InputIterator first, InputIterator last);
+    template<container-compatible-range<T> R>
+      constexpr iterator insert_range(const_iterator position, R&& rg);     // freestanding-deleted
+    constexpr iterator insert(const_iterator position,                      // freestanding-deleted
+                              initializer_list<T> il);
+    constexpr iterator erase(const_iterator position);
+    constexpr iterator erase(const_iterator first, const_iterator last);
+    constexpr void swap(inplace_vector& x)
+      noexcept(N == 0 || (is_nothrow_swappable_v<T> &&
+                          is_nothrow_move_constructible_v<T>));
+    constexpr void clear() noexcept;
+
+    constexpr friend bool operator==(const inplace_vector& x,
+                                     const inplace_vector& y);
+    constexpr friend synth-three-way-result<T>
+      operator<=>(const inplace_vector& x, const inplace_vector& y);
+    constexpr friend void swap(inplace_vector& x, inplace_vector& y)
+      noexcept(N == 0 || (is_nothrow_swappable_v<T> &&
+                          is_nothrow_move_constructible_v<T>))
+      { x.swap(y); }
+  };
+
+  // [inplace.vector.erasure], erasure
+  template<class T, size_t N, class U = T>
+    constexpr typename inplace_vector<T, N>::size_type
+      erase(inplace_vector<T, N>& c, const U& value);
+  template<class T, size_t N, class Predicate>
+    constexpr typename inplace_vector<T, N>::size_type
+      erase_if(inplace_vector<T, N>& c, Predicate pred);
+} // namespace std
+*/
+
+#include <__algorithm/copy.h>
+#include <__algorithm/equal.h>
+#include <__algorithm/lexicographical_compare_three_way.h>
+#include <__algorithm/min.h>
+#include <__algorithm/move.h>
+#include <__algorithm/move_backward.h>
+#include <__algorithm/remove.h>
+#include <__algorithm/remove_if.h>
+#include <__algorithm/rotate.h>
+#include <__algorithm/swap_ranges.h>
+#include <__compare/synth_three_way.h>
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <__iterator/distance.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/move_iterator.h>
+#include <__iterator/reverse_iterator.h>
+#include <__iterator/size.h>
+#include <__iterator/wrap_iter.h>
+#include <__memory/addressof.h>
+#include <__memory/construct_at.h>
+#include <__memory/pointer_traits.h>
+#include <__memory/voidify.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/container_compatible_range.h>
+#include <__ranges/dangling.h>
+#include <__ranges/from_range.h>
+#include <__type_traits/conditional.h>
+#include <__type_traits/is_nothrow_assignable.h>
+#include <__type_traits/is_nothrow_constructible.h>
+#include <__type_traits/is_swappable.h>
+#include <__type_traits/is_trivially_assignable.h>
+#include <__type_traits/is_trivially_constructible.h>
+#include <__type_traits/is_trivially_destructible.h>
+#include <__type_traits/is_trivially_relocatable.h>
+#include <__utility/cmp.h>
+#include <__utility/forward.h>
+#include <__utility/unreachable.h>
+#include <new>
+#include <stdexcept>
+
+// standard-mandated includes
+
+// [inplace.vector.syn]
+#include <compare>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 26
----------------
philnik777 wrote:

```suggestion
#if _LIBCPP_STD_VER >= 26

_LIBCPP_BEGIN_NAMESPACE_STD
```

https://github.com/llvm/llvm-project/pull/105981


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