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 <bits/alloc_traits.h>
  41 #include <bits/ptr_traits.h>
  42
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   /// Base class for node handle types of maps and sets.
  48   template<typename _Val, typename _NodeAlloc>
  49     class _Node_handle_common
  50     {
  51       using _AllocTraits = allocator_traits<_NodeAlloc>;
  52
  53     public:
  54       using allocator_type = __alloc_rebind<_NodeAlloc, _Val>;
  55
  56       allocator_type
  57       get_allocator() const noexcept
  58       {
  59         __glibcxx_assert(!this->empty());
  60         return allocator_type(*_M_alloc);
  61       }
  62
  63       explicit operator bool() const noexcept { return _M_ptr != nullptr; }
  64
  65       bool empty() const noexcept { return _M_ptr == nullptr; }
  66
  67     protected:
  68       constexpr _Node_handle_common() noexcept : _M_ptr(), _M_alloc() {}
  69
  70       ~_Node_handle_common() { _M_destroy(); }
  71
  72       _Node_handle_common(_Node_handle_common&& __nh) noexcept
  73       : _M_ptr(__nh._M_ptr), _M_alloc(std::move(__nh._M_alloc))
  74       {
  75         __nh._M_ptr = nullptr;
  76         __nh._M_alloc = nullopt;
  77       }
  78
  79       _Node_handle_common&
  80       operator=(_Node_handle_common&& __nh) noexcept
  81       {
  82         _M_destroy();
  83         _M_ptr = __nh._M_ptr;
  84         if constexpr (is_move_assignable_v<_NodeAlloc>)
  85           {
  86             if (_AllocTraits::propagate_on_container_move_assignment::value
  87                 || !this->_M_alloc)
  88               this->_M_alloc = std::move(__nh._M_alloc);
  89             else
  90               __glibcxx_assert(this->_M_alloc == __nh._M_alloc);
  91           }
  92         else
  93           __glibcxx_assert(_M_alloc);
  94         __nh._M_ptr = nullptr;
  95         __nh._M_alloc = nullopt;
  96         return *this;
  97       }
  98
  99       _Node_handle_common(typename _AllocTraits::pointer __ptr,
 100                           const _NodeAlloc& __alloc)
 101       : _M_ptr(__ptr), _M_alloc(__alloc) { }
 102
 103       void
 104       _M_swap(_Node_handle_common& __nh) noexcept
 105       {
 106         using std::swap;
 107         swap(_M_ptr, __nh._M_ptr);
 108         if (_AllocTraits::propagate_on_container_swap
 109             || !_M_alloc || !__nh._M_alloc)
 110           _M_alloc.swap(__nh._M_alloc);
 111         else
 112           __glibcxx_assert(_M_alloc == __nh._M_alloc);
 113       }
 114
 115     private:
 116       void
 117       _M_destroy() noexcept
 118       {
 119         if (_M_ptr != nullptr)
 120           {
 121             allocator_type __alloc(*_M_alloc);
 122             allocator_traits<allocator_type>::destroy(__alloc,
 123                                                       _M_ptr->_M_valptr());
 124             _AllocTraits::deallocate(*_M_alloc, _M_ptr, 1);
 125           }
 126       }
 127
 128     protected:
 129       typename _AllocTraits::pointer    _M_ptr;
 130     private:
 131       optional<_NodeAlloc>              _M_alloc;
 132
 133       template<typename _Key2, typename _Value2, typename _KeyOfValue,
 134                typename _Compare, typename _ValueAlloc>
 135         friend class _Rb_tree;
 136     };
 137
 138   /// Node handle type for maps.
 139   template<typename _Key, typename _Value, typename _NodeAlloc>
 140     class _Node_handle : public _Node_handle_common<_Value, _NodeAlloc>
 141     {
 142     public:
 143       constexpr _Node_handle() noexcept = default;
 144       ~_Node_handle() = default;
 145       _Node_handle(_Node_handle&&) noexcept = default;
 146
 147       _Node_handle&
 148       operator=(_Node_handle&&) noexcept = default;
 149
 150       using key_type = _Key;
 151       using mapped_type = typename _Value::second_type;
 152
 153       key_type&
 154       key() const noexcept
 155       {
 156         __glibcxx_assert(!this->empty());
 157         return *_M_pkey;
 158       }
 159
 160       mapped_type&
 161       mapped() const noexcept
 162       {
 163         __glibcxx_assert(!this->empty());
 164         return *_M_pmapped;
 165       }
 166
 167       void
 168       swap(_Node_handle& __nh) noexcept
 169       {
 170         this->_M_swap(__nh);
 171         using std::swap;
 172         swap(_M_pkey, __nh._M_pkey);
 173         swap(_M_pmapped, __nh._M_pmapped);
 174       }
 175
 176       friend void
 177       swap(_Node_handle& __x, _Node_handle& __y)
 178       noexcept(noexcept(__x.swap(__y)))
 179       { __x.swap(__y); }
 180
 181     private:
 182       using _AllocTraits = allocator_traits<_NodeAlloc>;
 183
 184       _Node_handle(typename _AllocTraits::pointer __ptr,
 185                    const _NodeAlloc& __alloc)
 186       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc)
 187       {
 188         if (__ptr)
 189           {
 190             auto& __key = const_cast<_Key&>(__ptr->_M_valptr()->first);
 191             _M_pkey = _S_pointer_to(__key);
 192             _M_pmapped = _S_pointer_to(__ptr->_M_valptr()->second);
 193           }
 194         else
 195           {
 196             _M_pkey = nullptr;
 197             _M_pmapped = nullptr;
 198           }
 199       }
 200
 201       template<typename _Tp>
 202         using __pointer = __ptr_rebind<typename _AllocTraits::pointer, _Tp>;
 203
 204       __pointer<_Key>                           _M_pkey = nullptr;
 205       __pointer<typename _Value::second_type>   _M_pmapped = nullptr;
 206
 207       template<typename _Tp>
 208         __pointer<_Tp>
 209         _S_pointer_to(_Tp& __obj)
 210         { return pointer_traits<__pointer<_Tp>>::pointer_to(__obj); }
 211
 212       const key_type&
 213       _M_key() const noexcept { return key(); }
 214
 215       template<typename _Key2, typename _Value2, typename _KeyOfValue,
 216                typename _Compare, typename _ValueAlloc>
 217         friend class _Rb_tree;
 218
 219       template<typename _Key2, typename _Value2, typename _ValueAlloc,
 220                typename _ExtractKey, typename _Equal,
 221                typename _H1, typename _H2, typename _Hash,
 222                typename _RehashPolicy, typename _Traits>
 223         friend class _Hashtable;
 224     };
 225
 226   /// Node handle type for sets.
 227   template<typename _Value, typename _NodeAlloc>
 228     class _Node_handle<_Value, _Value, _NodeAlloc>
 229     : public _Node_handle_common<_Value, _NodeAlloc>
 230     {
 231     public:
 232       constexpr _Node_handle() noexcept = default;
 233       ~_Node_handle() = default;
 234       _Node_handle(_Node_handle&&) noexcept = default;
 235
 236       _Node_handle&
 237       operator=(_Node_handle&&) noexcept = default;
 238
 239       using value_type = _Value;
 240
 241       value_type&
 242       value() const noexcept
 243       {
 244         __glibcxx_assert(!this->empty());
 245         return *this->_M_ptr->_M_valptr();
 246       }
 247
 248       void
 249       swap(_Node_handle& __nh) noexcept
 250       { this->_M_swap(__nh); }
 251
 252       friend void
 253       swap(_Node_handle& __x, _Node_handle& __y)
 254       noexcept(noexcept(__x.swap(__y)))
 255       { __x.swap(__y); }
 256
 257     private:
 258       using _AllocTraits = allocator_traits<_NodeAlloc>;
 259
 260       _Node_handle(typename _AllocTraits::pointer __ptr,
 261                    const _NodeAlloc& __alloc)
 262       : _Node_handle_common<_Value, _NodeAlloc>(__ptr, __alloc) { }
 263
 264       const value_type&
 265       _M_key() const noexcept { return value(); }
 266
 267       template<typename _Key, typename _Val, typename _KeyOfValue,
 268                typename _Compare, typename _Alloc>
 269         friend class _Rb_tree;
 270
 271       template<typename _Key2, typename _Value2, typename _ValueAlloc,
 272                typename _ExtractKey, typename _Equal,
 273                typename _H1, typename _H2, typename _Hash,
 274                typename _RehashPolicy, typename _Traits>
 275         friend class _Hashtable;
 276     };
 277
 278   /// Return type of insert(node_handle&&) on unique maps/sets.
 279   template<typename _Iterator, typename _NodeHandle>
 280     struct _Node_insert_return
 281     {
 282       _Iterator         position = _Iterator();
 283       bool              inserted = false;
 284       _NodeHandle       node;
 285     };
 286
 287 _GLIBCXX_END_NAMESPACE_VERSION
 288 } // namespace std
 289
 290 #endif // C++17
 291 #endif