libstdc++-v3/include/bits/node_handle.h

   1 // Node handles for containers -*- C++ -*-
   2
   3 // Copyright (C) 2016-2017 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/node_handle.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly.
  28  *  @headername{map,set,unordered_map,unordered_set}
  29  */
  30
  31 #ifndef _NODE_HANDLE
  32 #define _NODE_HANDLE 1
  33
  34 #pragma GCC system_header
  35
  36 #if __cplusplus > 201402L
  37 # define __cpp_lib_node_extract 201606
  38
  39 #include <optional>
  40 #include <tuple>
  41 #include <bits/alloc_traits.h>
  42 #include <bits/ptr_traits.h>
  43
  44 namespace std _GLIBCXX_VISIBILITY(default)
  45 {
  46 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  47
  48   /// Base class for node handle types of maps and sets.
  49   template<typename _Val, typename _NodeAlloc>
  50     class _Node_handle_common
  51     {
  52       using _AllocTraits = allocator_traits<_NodeAlloc>;
  53
  54     public:
  55       using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
  56
  57       allocator_type
  58       get_allocator() const noexcept
  59       {
  60         __glibcxx_assert(!this->empty());
  61         return allocator_type(*_M_alloc);
  62       }
  63
  64       explicit operator bool() const noexcept { return _M_ptr != nullptr; }
  65
  66       bool empty() const noexcept { return _M_ptr == nullptr; }
  67
  68     protected:
  69       constexpr _Node_handle_common() noexcept : _M_ptr(), _M_alloc() {}
  70
  71       ~_Node_handle_common() { _M_destroy(); }
  72
  73       _Node_handle_common(_Node_handle_common&& __nh) noexcept
  74       : _M_ptr(__nh._M_ptr), _M_alloc(std::move(__nh._M_alloc))
  75       {
  76         __nh._M_ptr = nullptr;
  77         __nh._M_alloc = nullopt;
  78       }
  79
  80       _Node_handle_common&
  81       operator=(_Node_handle_common&& __nh) noexcept
  82       {
  83         _M_destroy();
  84         _M_ptr = __nh._M_ptr;
  85         if constexpr (is_move_assignable_v<_NodeAlloc>)
  86           {
  87             if (_AllocTraits::propagate_on_container_move_assignment::value
  88                 || !this->_M_alloc)
  89               this->_M_alloc = std::move(__nh._M_alloc);
  90             else
  91               __glibcxx_assert(this->_M_alloc == __nh._M_alloc);
  92           }
  93         else
  94           __glibcxx_assert(_M_alloc);
  95         __nh._M_ptr = nullptr;
  96         __nh._M_alloc = nullopt;
  97         return *this;
  98       }
  99
 100       _Node_handle_common(typename _AllocTraits::pointer __ptr,
 101                           const _NodeAlloc& __alloc)
 102       : _M_ptr(__ptr), _M_alloc(__alloc) { }
 103
 104       void
 105       _M_swap(_Node_handle_common& __nh) noexcept
 106       {
 107         using std::swap;
 108         swap(_M_ptr, __nh._M_ptr);
 109         if (_AllocTraits::propagate_on_container_swap
 110             || !_M_alloc || !__nh._M_alloc)
 111           _M_alloc.swap(__nh._M_alloc);
 112         else
 113           __glibcxx_assert(_M_alloc == __nh._M_alloc);
 114       }
 115
 116     private:
 117       void
 118       _M_destroy() noexcept
 119       {
 120         if (_M_ptr != nullptr)
 121           {
 122             allocator_type __alloc(*_M_alloc);
 123             allocator_traits<allocator_type>::destroy(__alloc,
 124                                                       _M_ptr->_M_valptr());
 125             _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
 126           }
 127       }
 128
 129     protected:
 130       typename _AllocTraits::pointer    _M_ptr;
 131     private:
 132       optional<_NodeAlloc>              _M_alloc;
 133
 134       template<typename _Key2, typename _Value2, typename _KeyOfValue,
 135                typename _Compare, typename _ValueAlloc>
 136         friend class _Rb_tree;
 137     };
 138
 139   /// Node handle type for maps.
 140   template<typename _Key, typename _Value, typename _NodeAlloc>
 141     class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
 142     {
 143     public:
 144       constexpr _Node_handle() noexcept = default;
 145       ~_Node_handle() = default;
 146       _Node_handle(_Node_handle&&) noexcept = default;
 147
 148       _Node_handle&
 149       operator=(_Node_handle&&) noexcept = default;
 150
 151       using key_type = _Key;
 152       using mapped_type = typename _Value::second_type;
 153
 154       key_type&
 155       key() const noexcept
 156       {
 157         __glibcxx_assert(!this->empty());
 158         return *_M_pkey;
 159       }
 160
 161       mapped_type&
 162       mapped() const noexcept
 163       {
 164         __glibcxx_assert(!this->empty());
 165         return *_M_pmapped;
 166       }
 167
 168       void
 169       swap(_Node_handle& __nh) noexcept
 170       {
 171         this->_M_swap(__nh);
 172         using std::swap;
 173         swap(_M_pkey, __nh._M_pkey);
 174         swap(_M_pmapped, __nh._M_pmapped);
 175       }
 176
 177       friend void
 178       swap(_Node_handle& __x, _Node_handle& __y)
 179       noexcept(noexcept(__x.swap(__y)))
 180       { __x.swap(__y); }
 181
 182     private:
 183       using _AllocTraits = allocator_traits<_NodeAlloc>;
 184
 185       _Node_handle(typename _AllocTraits::pointer __ptr,
 186                    const _NodeAlloc& __alloc)
 187       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
 188       {
 189         if (__ptr)
 190           {
 191             auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
 192             _M_pkey = _S_pointer_to(__key);
 193             _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
 194           }
 195         else
 196           {
 197             _M_pkey = nullptr;
 198             _M_pmapped = nullptr;
 199           }
 200       }
 201
 202       template<typename _Tp>
 203         using __pointer = __ptr_rebind<typename _AllocTraits::pointer, _Tp>;
 204
 205       __pointer<_Key>                           _M_pkey = nullptr;
 206       __pointer<typename _Value::second_type>   _M_pmapped = nullptr;
 207
 208       template<typename _Tp>
 209         __pointer<_Tp>
 210         _S_pointer_to(_Tp& __obj)
 211         { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
 212
 213       const key_type&
 214       _M_key() const noexcept { return key(); }
 215
 216       template<typename _Key2, typename _Value2, typename _KeyOfValue,
 217                typename _Compare, typename _ValueAlloc>
 218         friend class _Rb_tree;
 219
 220       template<typename _Key2, typename _Value2, typename _ValueAlloc,
 221                typename _ExtractKey, typename _Equal,
 222                typename _H1, typename _H2, typename _Hash,
 223                typename _RehashPolicy, typename _Traits>
 224         friend class _Hashtable;
 225     };
 226
 227   /// Node handle type for sets.
 228   template<typename _Value, typename _NodeAlloc>
 229     class _Node_handle<_Value, _Value, _NodeAlloc>
 230     : public _Node_handle_common<_Value, _NodeAlloc>
 231     {
 232     public:
 233       constexpr _Node_handle() noexcept = default;
 234       ~_Node_handle() = default;
 235       _Node_handle(_Node_handle&&) noexcept = default;
 236
 237       _Node_handle&
 238       operator=(_Node_handle&&) noexcept = default;
 239
 240       using value_type = _Value;
 241
 242       value_type&
 243       value() const noexcept
 244       {
 245         __glibcxx_assert(!this->empty());
 246         return *this->_M_ptr->_M_valptr();
 247       }
 248
 249       void
 250       swap(_Node_handle& __nh) noexcept
 251       { this->_M_swap(__nh); }
 252
 253       friend void
 254       swap(_Node_handle& __x, _Node_handle& __y)
 255       noexcept(noexcept(__x.swap(__y)))
 256       { __x.swap(__y); }
 257
 258     private:
 259       using _AllocTraits = allocator_traits<_NodeAlloc>;
 260
 261       _Node_handle(typename _AllocTraits::pointer __ptr,
 262                    const _NodeAlloc& __alloc)
 263       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
 264
 265       const value_type&
 266       _M_key() const noexcept { return value(); }
 267
 268       template<typename _Key, typename _Val, typename _KeyOfValue,
 269                typename _Compare, typename _Alloc>
 270         friend class _Rb_tree;
 271
 272       template<typename _Key2, typename _Value2, typename _ValueAlloc,
 273                typename _ExtractKey, typename _Equal,
 274                typename _H1, typename _H2, typename _Hash,
 275                typename _RehashPolicy, typename _Traits>
 276         friend class _Hashtable;
 277     };
 278
 279   /// Return type of insert(node_handle&&) on unique maps/sets.
 280   template<typename _Iterator, typename _NodeHandle>
 281     struct _Node_insert_return
 282     {
 283       _Iterator         position = _Iterator();
 284       bool              inserted = false;
 285       _NodeHandle       node;
 286
 287       template<size_t _Idx>
 288         decltype(auto) get() &
 289         { return std::get<_Idx>(std::tie(inserted, position, node)); }
 290
 291       template<size_t _Idx>
 292         decltype(auto) get() const &
 293         { return std::get<_Idx>(std::tie(inserted, position, node)); }
 294
 295       template<size_t _Idx>
 296         decltype(auto) get() &&
 297         {
 298           return std::move(std::get<_Idx>(std::tie(inserted, position, node)));
 299         }
 300
 301       template<size_t _Idx>
 302         decltype(auto) get() const &&
 303         {
 304           return std::move(std::get<_Idx>(std::tie(inserted, position, node)));
 305         }
 306     };
 307
 308 _GLIBCXX_END_NAMESPACE_VERSION
 309 } // namespace std
 310
 311 #endif // C++17
 312 #endif