xref: /llvm-project-15.0.7/libcxx/include/__node_handle (revision 368faaca)

// -*- 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___NODE_HANDLE
#define _LIBCPP___NODE_HANDLE

/*

template<unspecified>
class node-handle {
public:
  using value_type     = see below;     // not present for map containers
  using key_type       = see below;     // not present for set containers
  using mapped_type    = see below;     // not present for set containers
  using allocator_type = see below;

private:
  using container_node_type = unspecified;                  // exposition only
  using ator_traits = allocator_traits<allocator_type>;     // exposition only

  typename ator_traits::template
    rebind_traits<container_node_type>::pointer ptr_;       // exposition only
  optional<allocator_type> alloc_;                          // exposition only

public:
  // [container.node.cons], constructors, copy, and assignment
  constexpr node-handle() noexcept : ptr_(), alloc_() {}
  node-handle(node-handle&&) noexcept;
  node-handle& operator=(node-handle&&);

  // [container.node.dtor], destructor
  ~node-handle();

  // [container.node.observers], observers
  value_type& value() const;            // not present for map containers
  key_type& key() const;                // not present for set containers
  mapped_type& mapped() const;          // not present for set containers

  allocator_type get_allocator() const;
  explicit operator bool() const noexcept;
  [[nodiscard]] bool empty() const noexcept; // nodiscard since C++20

  // [container.node.modifiers], modifiers
  void swap(node-handle&)
    noexcept(ator_traits::propagate_on_container_swap::value ||
             ator_traits::is_always_equal::value);

  friend void swap(node-handle& x, node-handle& y) noexcept(noexcept(x.swap(y))) {
    x.swap(y);
  }
};

*/

#include <__assert>
#include <__config>
#include <memory>
#include <optional>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 14

// Specialized in __tree & __hash_table for their _NodeType.
template <class _NodeType, class _Alloc>
struct __generic_container_node_destructor;

template <class _NodeType, class _Alloc,
          template <class, class> class _MapOrSetSpecifics>
class _LIBCPP_TEMPLATE_VIS __basic_node_handle
    : public _MapOrSetSpecifics<
          _NodeType,
          __basic_node_handle<_NodeType, _Alloc, _MapOrSetSpecifics>>
{
    template <class _Tp, class _Compare, class _Allocator>
        friend class __tree;
    template <class _Tp, class _Hash, class _Equal, class _Allocator>
        friend class __hash_table;
    friend struct _MapOrSetSpecifics<
        _NodeType, __basic_node_handle<_NodeType, _Alloc, _MapOrSetSpecifics>>;

    typedef allocator_traits<_Alloc> __alloc_traits;
    typedef typename __rebind_pointer<typename __alloc_traits::void_pointer,
                                      _NodeType>::type
        __node_pointer_type;

public:
    typedef _Alloc allocator_type;

private:
    __node_pointer_type __ptr_ = nullptr;
    optional<allocator_type> __alloc_;

    _LIBCPP_INLINE_VISIBILITY
    void __release_ptr()
    {
        __ptr_ = nullptr;
        __alloc_ = _VSTD::nullopt;
    }

    _LIBCPP_INLINE_VISIBILITY
    void __destroy_node_pointer()
    {
        if (__ptr_ != nullptr)
        {
            typedef typename __allocator_traits_rebind<
                allocator_type, _NodeType>::type __node_alloc_type;
            __node_alloc_type __alloc(*__alloc_);
            __generic_container_node_destructor<_NodeType, __node_alloc_type>(
                __alloc, true)(__ptr_);
            __ptr_ = nullptr;
        }
    }

    _LIBCPP_INLINE_VISIBILITY
    __basic_node_handle(__node_pointer_type __ptr,
                        allocator_type const& __alloc)
            : __ptr_(__ptr), __alloc_(__alloc)
    {
    }

public:
    _LIBCPP_INLINE_VISIBILITY
    __basic_node_handle() = default;

    _LIBCPP_INLINE_VISIBILITY
    __basic_node_handle(__basic_node_handle&& __other) noexcept
            : __ptr_(__other.__ptr_),
              __alloc_(_VSTD::move(__other.__alloc_))
    {
        __other.__ptr_ = nullptr;
        __other.__alloc_ = _VSTD::nullopt;
    }

    _LIBCPP_INLINE_VISIBILITY
    __basic_node_handle& operator=(__basic_node_handle&& __other)
    {
        _LIBCPP_ASSERT(
            __alloc_ == _VSTD::nullopt ||
            __alloc_traits::propagate_on_container_move_assignment::value ||
            __alloc_ == __other.__alloc_,
            "node_type with incompatible allocator passed to "
            "node_type::operator=(node_type&&)");

        __destroy_node_pointer();
        __ptr_ = __other.__ptr_;

        if (__alloc_traits::propagate_on_container_move_assignment::value ||
            __alloc_ == _VSTD::nullopt)
            __alloc_ = _VSTD::move(__other.__alloc_);

        __other.__ptr_ = nullptr;
        __other.__alloc_ = _VSTD::nullopt;

        return *this;
    }

    _LIBCPP_INLINE_VISIBILITY
    allocator_type get_allocator() const { return *__alloc_; }

    _LIBCPP_INLINE_VISIBILITY
    explicit operator bool() const { return __ptr_ != nullptr; }

    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
    bool empty() const { return __ptr_ == nullptr; }

    _LIBCPP_INLINE_VISIBILITY
    void swap(__basic_node_handle& __other) noexcept(
        __alloc_traits::propagate_on_container_swap::value ||
        __alloc_traits::is_always_equal::value)
    {
        using _VSTD::swap;
        swap(__ptr_, __other.__ptr_);
        if (__alloc_traits::propagate_on_container_swap::value ||
            __alloc_ == _VSTD::nullopt || __other.__alloc_ == _VSTD::nullopt)
            swap(__alloc_, __other.__alloc_);
    }

    _LIBCPP_INLINE_VISIBILITY
    friend void swap(__basic_node_handle& __a, __basic_node_handle& __b)
        noexcept(noexcept(__a.swap(__b))) { __a.swap(__b); }

    _LIBCPP_INLINE_VISIBILITY
    ~__basic_node_handle()
    {
        __destroy_node_pointer();
    }
};

template <class _NodeType, class _Derived>
struct __set_node_handle_specifics
{
    typedef typename _NodeType::__node_value_type value_type;

    _LIBCPP_INLINE_VISIBILITY
    value_type& value() const
    {
        return static_cast<_Derived const*>(this)->__ptr_->__value_;
    }
};

template <class _NodeType, class _Derived>
struct __map_node_handle_specifics
{
    typedef typename _NodeType::__node_value_type::key_type key_type;
    typedef typename _NodeType::__node_value_type::mapped_type mapped_type;

    _LIBCPP_INLINE_VISIBILITY
    key_type& key() const
    {
        return static_cast<_Derived const*>(this)->
            __ptr_->__value_.__ref().first;
    }

    _LIBCPP_INLINE_VISIBILITY
    mapped_type& mapped() const
    {
        return static_cast<_Derived const*>(this)->
            __ptr_->__value_.__ref().second;
    }
};

template <class _NodeType, class _Alloc>
using __set_node_handle =
    __basic_node_handle< _NodeType, _Alloc, __set_node_handle_specifics>;

template <class _NodeType, class _Alloc>
using __map_node_handle =
    __basic_node_handle< _NodeType, _Alloc, __map_node_handle_specifics>;

template <class _Iterator, class _NodeType>
struct _LIBCPP_TEMPLATE_VIS __insert_return_type
{
    _Iterator position;
    bool inserted;
    _NodeType node;
};

#endif // _LIBCPP_STD_VER > 14

_LIBCPP_END_NAMESPACE_STD

#endif  // _LIBCPP___NODE_HANDLE