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

   1 // RB tree implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001-2017 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 /*
  26  *
  27  * Copyright (c) 1996,1997
  28  * Silicon Graphics Computer Systems, Inc.
  29  *
  30  * Permission to use, copy, modify, distribute and sell this software
  31  * and its documentation for any purpose is hereby granted without fee,
  32  * provided that the above copyright notice appear in all copies and
  33  * that both that copyright notice and this permission notice appear
  34  * in supporting documentation.  Silicon Graphics makes no
  35  * representations about the suitability of this software for any
  36  * purpose.  It is provided "as is" without express or implied warranty.
  37  *
  38  *
  39  * Copyright (c) 1994
  40  * Hewlett-Packard Company
  41  *
  42  * Permission to use, copy, modify, distribute and sell this software
  43  * and its documentation for any purpose is hereby granted without fee,
  44  * provided that the above copyright notice appear in all copies and
  45  * that both that copyright notice and this permission notice appear
  46  * in supporting documentation.  Hewlett-Packard Company makes no
  47  * representations about the suitability of this software for any
  48  * purpose.  It is provided "as is" without express or implied warranty.
  49  *
  50  *
  51  */
  52
  53 /** @file bits/stl_tree.h
  54  *  This is an internal header file, included by other library headers.
  55  *  Do not attempt to use it directly. @headername{map,set}
  56  */
  57
  58 #ifndef _STL_TREE_H
  59 #define _STL_TREE_H 1
  60
  61 #pragma GCC system_header
  62
  63 #include <bits/stl_algobase.h>
  64 #include <bits/allocator.h>
  65 #include <bits/stl_function.h>
  66 #include <bits/cpp_type_traits.h>
  67 #include <ext/alloc_traits.h>
  68 #if __cplusplus >= 201103L
  69 # include <ext/aligned_buffer.h>
  70 #endif
  71 #if __cplusplus > 201402L
  72 # include <bits/node_handle.h>
  73 #endif
  74
  75 namespace std _GLIBCXX_VISIBILITY(default)
  76 {
  77 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  78
  79 #if __cplusplus > 201103L
  80 # define __cpp_lib_generic_associative_lookup 201304
  81 #endif
  82
  83   // Red-black tree class, designed for use in implementing STL
  84   // associative containers (set, multiset, map, and multimap). The
  85   // insertion and deletion algorithms are based on those in Cormen,
  86   // Leiserson, and Rivest, Introduction to Algorithms (MIT Press,
  87   // 1990), except that
  88   //
  89   // (1) the header cell is maintained with links not only to the root
  90   // but also to the leftmost node of the tree, to enable constant
  91   // time begin(), and to the rightmost node of the tree, to enable
  92   // linear time performance when used with the generic set algorithms
  93   // (set_union, etc.)
  94   //
  95   // (2) when a node being deleted has two children its successor node
  96   // is relinked into its place, rather than copied, so that the only
  97   // iterators invalidated are those referring to the deleted node.
  98
  99   enum _Rb_tree_color { _S_red = false, _S_black = true };
 100
 101   struct _Rb_tree_node_base
 102   {
 103     typedef _Rb_tree_node_base* _Base_ptr;
 104     typedef const _Rb_tree_node_base* _Const_Base_ptr;
 105
 106     _Rb_tree_color      _M_color;
 107     _Base_ptr           _M_parent;
 108     _Base_ptr           _M_left;
 109     _Base_ptr           _M_right;
 110
 111     static _Base_ptr
 112     _S_minimum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 113     {
 114       while (__x->_M_left != 0) __x = __x->_M_left;
 115       return __x;
 116     }
 117
 118     static _Const_Base_ptr
 119     _S_minimum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 120     {
 121       while (__x->_M_left != 0) __x = __x->_M_left;
 122       return __x;
 123     }
 124
 125     static _Base_ptr
 126     _S_maximum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 127     {
 128       while (__x->_M_right != 0) __x = __x->_M_right;
 129       return __x;
 130     }
 131
 132     static _Const_Base_ptr
 133     _S_maximum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 134     {
 135       while (__x->_M_right != 0) __x = __x->_M_right;
 136       return __x;
 137     }
 138   };
 139
 140   // Helper type offering value initialization guarantee on the compare functor.
 141   template<typename _Key_compare>
 142     struct _Rb_tree_key_compare
 143     {
 144       _Key_compare              _M_key_compare;
 145
 146       _Rb_tree_key_compare()
 147       _GLIBCXX_NOEXCEPT_IF(
 148         is_nothrow_default_constructible<_Key_compare>::value)
 149       : _M_key_compare()
 150       { }
 151
 152       _Rb_tree_key_compare(const _Key_compare& __comp)
 153       : _M_key_compare(__comp)
 154       { }
 155
 156 #if __cplusplus >= 201103L
 157       // Copy constructor added for consistency with C++98 mode.
 158       _Rb_tree_key_compare(const _Rb_tree_key_compare&) = default;
 159
 160       _Rb_tree_key_compare(_Rb_tree_key_compare&& __x)
 161         noexcept(is_nothrow_copy_constructible<_Key_compare>::value)
 162       : _M_key_compare(__x._M_key_compare)
 163       { }
 164 #endif
 165     };
 166
 167   // Helper type to manage default initialization of node count and header.
 168   struct _Rb_tree_header
 169   {
 170     _Rb_tree_node_base  _M_header;
 171     size_t              _M_node_count; // Keeps track of size of tree.
 172
 173     _Rb_tree_header() _GLIBCXX_NOEXCEPT
 174     {
 175       _M_header._M_color = _S_red;
 176       _M_reset();
 177     }
 178
 179 #if __cplusplus >= 201103L
 180     _Rb_tree_header(_Rb_tree_header&& __x) noexcept
 181     {
 182       if (__x._M_header._M_parent != nullptr)
 183         _M_move_data(__x);
 184       else
 185         {
 186           _M_header._M_color = _S_red;
 187           _M_reset();
 188         }
 189     }
 190 #endif
 191
 192     void
 193     _M_move_data(_Rb_tree_header& __from)
 194     {
 195       _M_header._M_color = __from._M_header._M_color;
 196       _M_header._M_parent = __from._M_header._M_parent;
 197       _M_header._M_left = __from._M_header._M_left;
 198       _M_header._M_right = __from._M_header._M_right;
 199       _M_header._M_parent->_M_parent = &_M_header;
 200       _M_node_count = __from._M_node_count;
 201
 202       __from._M_reset();
 203     }
 204
 205     void
 206     _M_reset()
 207     {
 208       _M_header._M_parent = 0;
 209       _M_header._M_left = &_M_header;
 210       _M_header._M_right = &_M_header;
 211       _M_node_count = 0;
 212     }
 213   };
 214
 215   template<typename _Val>
 216     struct _Rb_tree_node : public _Rb_tree_node_base
 217     {
 218       typedef _Rb_tree_node<_Val>* _Link_type;
 219
 220 #if __cplusplus < 201103L
 221       _Val _M_value_field;
 222
 223       _Val*
 224       _M_valptr()
 225       { return std::__addressof(_M_value_field); }
 226
 227       const _Val*
 228       _M_valptr() const
 229       { return std::__addressof(_M_value_field); }
 230 #else
 231       __gnu_cxx::__aligned_membuf<_Val> _M_storage;
 232
 233       _Val*
 234       _M_valptr()
 235       { return _M_storage._M_ptr(); }
 236
 237       const _Val*
 238       _M_valptr() const
 239       { return _M_storage._M_ptr(); }
 240 #endif
 241     };
 242
 243   _GLIBCXX_PURE _Rb_tree_node_base*
 244   _Rb_tree_increment(_Rb_tree_node_base* __x) throw ();
 245
 246   _GLIBCXX_PURE const _Rb_tree_node_base*
 247   _Rb_tree_increment(const _Rb_tree_node_base* __x) throw ();
 248
 249   _GLIBCXX_PURE _Rb_tree_node_base*
 250   _Rb_tree_decrement(_Rb_tree_node_base* __x) throw ();
 251
 252   _GLIBCXX_PURE const _Rb_tree_node_base*
 253   _Rb_tree_decrement(const _Rb_tree_node_base* __x) throw ();
 254
 255   template<typename _Tp>
 256     struct _Rb_tree_iterator
 257     {
 258       typedef _Tp  value_type;
 259       typedef _Tp& reference;
 260       typedef _Tp* pointer;
 261
 262       typedef bidirectional_iterator_tag iterator_category;
 263       typedef ptrdiff_t           difference_type;
 264
 265       typedef _Rb_tree_iterator<_Tp>    _Self;
 266       typedef _Rb_tree_node_base::_Base_ptr _Base_ptr;
 267       typedef _Rb_tree_node<_Tp>*          _Link_type;
 268
 269       _Rb_tree_iterator() _GLIBCXX_NOEXCEPT
 270       : _M_node() { }
 271
 272       explicit
 273       _Rb_tree_iterator(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 274       : _M_node(__x) { }
 275
 276       reference
 277       operator*() const _GLIBCXX_NOEXCEPT
 278       { return *static_cast<_Link_type>(_M_node)->_M_valptr(); }
 279
 280       pointer
 281       operator->() const _GLIBCXX_NOEXCEPT
 282       { return static_cast<_Link_type> (_M_node)->_M_valptr(); }
 283
 284       _Self&
 285       operator++() _GLIBCXX_NOEXCEPT
 286       {
 287         _M_node = _Rb_tree_increment(_M_node);
 288         return *this;
 289       }
 290
 291       _Self
 292       operator++(int) _GLIBCXX_NOEXCEPT
 293       {
 294         _Self __tmp = *this;
 295         _M_node = _Rb_tree_increment(_M_node);
 296         return __tmp;
 297       }
 298
 299       _Self&
 300       operator--() _GLIBCXX_NOEXCEPT
 301       {
 302         _M_node = _Rb_tree_decrement(_M_node);
 303         return *this;
 304       }
 305
 306       _Self
 307       operator--(int) _GLIBCXX_NOEXCEPT
 308       {
 309         _Self __tmp = *this;
 310         _M_node = _Rb_tree_decrement(_M_node);
 311         return __tmp;
 312       }
 313
 314       bool
 315       operator==(const _Self& __x) const _GLIBCXX_NOEXCEPT
 316       { return _M_node == __x._M_node; }
 317
 318       bool
 319       operator!=(const _Self& __x) const _GLIBCXX_NOEXCEPT
 320       { return _M_node != __x._M_node; }
 321
 322       _Base_ptr _M_node;
 323   };
 324
 325   template<typename _Tp>
 326     struct _Rb_tree_const_iterator
 327     {
 328       typedef _Tp        value_type;
 329       typedef const _Tp& reference;
 330       typedef const _Tp* pointer;
 331
 332       typedef _Rb_tree_iterator<_Tp> iterator;
 333
 334       typedef bidirectional_iterator_tag iterator_category;
 335       typedef ptrdiff_t                  difference_type;
 336
 337       typedef _Rb_tree_const_iterator<_Tp>              _Self;
 338       typedef _Rb_tree_node_base::_Const_Base_ptr       _Base_ptr;
 339       typedef const _Rb_tree_node<_Tp>*                 _Link_type;
 340
 341       _Rb_tree_const_iterator() _GLIBCXX_NOEXCEPT
 342       : _M_node() { }
 343
 344       explicit
 345       _Rb_tree_const_iterator(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 346       : _M_node(__x) { }
 347
 348       _Rb_tree_const_iterator(const iterator& __it) _GLIBCXX_NOEXCEPT
 349       : _M_node(__it._M_node) { }
 350
 351       iterator
 352       _M_const_cast() const _GLIBCXX_NOEXCEPT
 353       { return iterator(const_cast<typename iterator::_Base_ptr>(_M_node)); }
 354
 355       reference
 356       operator*() const _GLIBCXX_NOEXCEPT
 357       { return *static_cast<_Link_type>(_M_node)->_M_valptr(); }
 358
 359       pointer
 360       operator->() const _GLIBCXX_NOEXCEPT
 361       { return static_cast<_Link_type>(_M_node)->_M_valptr(); }
 362
 363       _Self&
 364       operator++() _GLIBCXX_NOEXCEPT
 365       {
 366         _M_node = _Rb_tree_increment(_M_node);
 367         return *this;
 368       }
 369
 370       _Self
 371       operator++(int) _GLIBCXX_NOEXCEPT
 372       {
 373         _Self __tmp = *this;
 374         _M_node = _Rb_tree_increment(_M_node);
 375         return __tmp;
 376       }
 377
 378       _Self&
 379       operator--() _GLIBCXX_NOEXCEPT
 380       {
 381         _M_node = _Rb_tree_decrement(_M_node);
 382         return *this;
 383       }
 384
 385       _Self
 386       operator--(int) _GLIBCXX_NOEXCEPT
 387       {
 388         _Self __tmp = *this;
 389         _M_node = _Rb_tree_decrement(_M_node);
 390         return __tmp;
 391       }
 392
 393       bool
 394       operator==(const _Self& __x) const _GLIBCXX_NOEXCEPT
 395       { return _M_node == __x._M_node; }
 396
 397       bool
 398       operator!=(const _Self& __x) const _GLIBCXX_NOEXCEPT
 399       { return _M_node != __x._M_node; }
 400
 401       _Base_ptr _M_node;
 402     };
 403
 404   template<typename _Val>
 405     inline bool
 406     operator==(const _Rb_tree_iterator<_Val>& __x,
 407                const _Rb_tree_const_iterator<_Val>& __y) _GLIBCXX_NOEXCEPT
 408     { return __x._M_node == __y._M_node; }
 409
 410   template<typename _Val>
 411     inline bool
 412     operator!=(const _Rb_tree_iterator<_Val>& __x,
 413                const _Rb_tree_const_iterator<_Val>& __y) _GLIBCXX_NOEXCEPT
 414     { return __x._M_node != __y._M_node; }
 415
 416   void
 417   _Rb_tree_insert_and_rebalance(const bool __insert_left,
 418                                 _Rb_tree_node_base* __x,
 419                                 _Rb_tree_node_base* __p,
 420                                 _Rb_tree_node_base& __header) throw ();
 421
 422   _Rb_tree_node_base*
 423   _Rb_tree_rebalance_for_erase(_Rb_tree_node_base* const __z,
 424                                _Rb_tree_node_base& __header) throw ();
 425
 426 #if __cplusplus > 201103L
 427   template<typename _Cmp, typename _SfinaeType, typename = __void_t<>>
 428     struct __has_is_transparent
 429     { };
 430
 431   template<typename _Cmp, typename _SfinaeType>
 432     struct __has_is_transparent<_Cmp, _SfinaeType,
 433                                 __void_t<typename _Cmp::is_transparent>>
 434     { typedef void type; };
 435 #endif
 436
 437 #if __cplusplus > 201402L
 438   template<typename _Tree1, typename _Cmp2>
 439     struct _Rb_tree_merge_helper { };
 440 #endif
 441
 442   template<typename _Key, typename _Val, typename _KeyOfValue,
 443            typename _Compare, typename _Alloc = allocator<_Val> >
 444     class _Rb_tree
 445     {
 446       typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
 447         rebind<_Rb_tree_node<_Val> >::other _Node_allocator;
 448
 449       typedef __gnu_cxx::__alloc_traits<_Node_allocator> _Alloc_traits;
 450
 451     protected:
 452       typedef _Rb_tree_node_base*               _Base_ptr;
 453       typedef const _Rb_tree_node_base*         _Const_Base_ptr;
 454       typedef _Rb_tree_node<_Val>*              _Link_type;
 455       typedef const _Rb_tree_node<_Val>*        _Const_Link_type;
 456
 457     private:
 458       // Functor recycling a pool of nodes and using allocation once the pool
 459       // is empty.
 460       struct _Reuse_or_alloc_node
 461       {
 462         _Reuse_or_alloc_node(_Rb_tree& __t)
 463           : _M_root(__t._M_root()), _M_nodes(__t._M_rightmost()), _M_t(__t)
 464         {
 465           if (_M_root)
 466             {
 467               _M_root->_M_parent = 0;
 468
 469               if (_M_nodes->_M_left)
 470                 _M_nodes = _M_nodes->_M_left;
 471             }
 472           else
 473             _M_nodes = 0;
 474         }
 475
 476 #if __cplusplus >= 201103L
 477         _Reuse_or_alloc_node(const _Reuse_or_alloc_node&) = delete;
 478 #endif
 479
 480         ~_Reuse_or_alloc_node()
 481         { _M_t._M_erase(static_cast<_Link_type>(_M_root)); }
 482
 483         template<typename _Arg>
 484           _Link_type
 485 #if __cplusplus < 201103L
 486           operator()(const _Arg& __arg)
 487 #else
 488           operator()(_Arg&& __arg)
 489 #endif
 490           {
 491             _Link_type __node = static_cast<_Link_type>(_M_extract());
 492             if (__node)
 493               {
 494                 _M_t._M_destroy_node(__node);
 495                 _M_t._M_construct_node(__node, _GLIBCXX_FORWARD(_Arg, __arg));
 496                 return __node;
 497               }
 498
 499             return _M_t._M_create_node(_GLIBCXX_FORWARD(_Arg, __arg));
 500           }
 501
 502       private:
 503         _Base_ptr
 504         _M_extract()
 505         {
 506           if (!_M_nodes)
 507             return _M_nodes;
 508
 509           _Base_ptr __node = _M_nodes;
 510           _M_nodes = _M_nodes->_M_parent;
 511           if (_M_nodes)
 512             {
 513               if (_M_nodes->_M_right == __node)
 514                 {
 515                   _M_nodes->_M_right = 0;
 516
 517                   if (_M_nodes->_M_left)
 518                     {
 519                       _M_nodes = _M_nodes->_M_left;
 520
 521                       while (_M_nodes->_M_right)
 522                         _M_nodes = _M_nodes->_M_right;
 523
 524                       if (_M_nodes->_M_left)
 525                         _M_nodes = _M_nodes->_M_left;
 526                     }
 527                 }
 528               else // __node is on the left.
 529                 _M_nodes->_M_left = 0;
 530             }
 531           else
 532             _M_root = 0;
 533
 534           return __node;
 535         }
 536
 537         _Base_ptr _M_root;
 538         _Base_ptr _M_nodes;
 539         _Rb_tree& _M_t;
 540       };
 541
 542       // Functor similar to the previous one but without any pool of nodes to
 543       // recycle.
 544       struct _Alloc_node
 545       {
 546         _Alloc_node(_Rb_tree& __t)
 547           : _M_t(__t) { }
 548
 549         template<typename _Arg>
 550           _Link_type
 551 #if __cplusplus < 201103L
 552           operator()(const _Arg& __arg) const
 553 #else
 554           operator()(_Arg&& __arg) const
 555 #endif
 556           { return _M_t._M_create_node(_GLIBCXX_FORWARD(_Arg, __arg)); }
 557
 558       private:
 559         _Rb_tree& _M_t;
 560       };
 561
 562     public:
 563       typedef _Key                              key_type;
 564       typedef _Val                              value_type;
 565       typedef value_type*                       pointer;
 566       typedef const value_type*                 const_pointer;
 567       typedef value_type&                       reference;
 568       typedef const value_type&                 const_reference;
 569       typedef size_t                            size_type;
 570       typedef ptrdiff_t                         difference_type;
 571       typedef _Alloc                            allocator_type;
 572
 573       _Node_allocator&
 574       _M_get_Node_allocator() _GLIBCXX_NOEXCEPT
 575       { return this->_M_impl; }
 576
 577       const _Node_allocator&
 578       _M_get_Node_allocator() const _GLIBCXX_NOEXCEPT
 579       { return this->_M_impl; }
 580
 581       allocator_type
 582       get_allocator() const _GLIBCXX_NOEXCEPT
 583       { return allocator_type(_M_get_Node_allocator()); }
 584
 585     protected:
 586       _Link_type
 587       _M_get_node()
 588       { return _Alloc_traits::allocate(_M_get_Node_allocator(), 1); }
 589
 590       void
 591       _M_put_node(_Link_type __p) _GLIBCXX_NOEXCEPT
 592       { _Alloc_traits::deallocate(_M_get_Node_allocator(), __p, 1); }
 593
 594 #if __cplusplus < 201103L
 595       void
 596       _M_construct_node(_Link_type __node, const value_type& __x)
 597       {
 598         __try
 599           { get_allocator().construct(__node->_M_valptr(), __x); }
 600         __catch(...)
 601           {
 602             _M_put_node(__node);
 603             __throw_exception_again;
 604           }
 605       }
 606
 607       _Link_type
 608       _M_create_node(const value_type& __x)
 609       {
 610         _Link_type __tmp = _M_get_node();
 611         _M_construct_node(__tmp, __x);
 612         return __tmp;
 613       }
 614
 615       void
 616       _M_destroy_node(_Link_type __p)
 617       { get_allocator().destroy(__p->_M_valptr()); }
 618 #else
 619       template<typename... _Args>
 620         void
 621         _M_construct_node(_Link_type __node, _Args&&... __args)
 622         {
 623           __try
 624             {
 625               ::new(__node) _Rb_tree_node<_Val>;
 626               _Alloc_traits::construct(_M_get_Node_allocator(),
 627                                        __node->_M_valptr(),
 628                                        std::forward<_Args>(__args)...);
 629             }
 630           __catch(...)
 631             {
 632               __node->~_Rb_tree_node<_Val>();
 633               _M_put_node(__node);
 634               __throw_exception_again;
 635             }
 636         }
 637
 638       template<typename... _Args>
 639         _Link_type
 640         _M_create_node(_Args&&... __args)
 641         {
 642           _Link_type __tmp = _M_get_node();
 643           _M_construct_node(__tmp, std::forward<_Args>(__args)...);
 644           return __tmp;
 645         }
 646
 647       void
 648       _M_destroy_node(_Link_type __p) noexcept
 649       {
 650         _Alloc_traits::destroy(_M_get_Node_allocator(), __p->_M_valptr());
 651         __p->~_Rb_tree_node<_Val>();
 652       }
 653 #endif
 654
 655       void
 656       _M_drop_node(_Link_type __p) _GLIBCXX_NOEXCEPT
 657       {
 658         _M_destroy_node(__p);
 659         _M_put_node(__p);
 660       }
 661
 662       template<typename _NodeGen>
 663         _Link_type
 664         _M_clone_node(_Const_Link_type __x, _NodeGen& __node_gen)
 665         {
 666           _Link_type __tmp = __node_gen(*__x->_M_valptr());
 667           __tmp->_M_color = __x->_M_color;
 668           __tmp->_M_left = 0;
 669           __tmp->_M_right = 0;
 670           return __tmp;
 671         }
 672
 673     protected:
 674 #if _GLIBCXX_INLINE_VERSION
 675       template<typename _Key_compare>
 676 #else
 677       // Unused _Is_pod_comparator is kept as it is part of mangled name.
 678       template<typename _Key_compare,
 679                bool /* _Is_pod_comparator */ = __is_pod(_Key_compare)>
 680 #endif
 681         struct _Rb_tree_impl
 682         : public _Node_allocator
 683         , public _Rb_tree_key_compare<_Key_compare>
 684         , public _Rb_tree_header
 685         {
 686           typedef _Rb_tree_key_compare<_Key_compare> _Base_key_compare;
 687
 688           _Rb_tree_impl()
 689             _GLIBCXX_NOEXCEPT_IF(
 690                 is_nothrow_default_constructible<_Node_allocator>::value
 691                 && is_nothrow_default_constructible<_Base_key_compare>::value )
 692           : _Node_allocator()
 693           { }
 694
 695           _Rb_tree_impl(const _Rb_tree_impl& __x)
 696           : _Node_allocator(_Alloc_traits::_S_select_on_copy(__x))
 697           , _Base_key_compare(__x._M_key_compare)
 698           { }
 699
 700 #if __cplusplus < 201103L
 701           _Rb_tree_impl(const _Key_compare& __comp, const _Node_allocator& __a)
 702           : _Node_allocator(__a), _Base_key_compare(__comp)
 703           { }
 704 #else
 705           _Rb_tree_impl(_Rb_tree_impl&&) = default;
 706
 707           _Rb_tree_impl(const _Key_compare& __comp, _Node_allocator&& __a)
 708           : _Node_allocator(std::move(__a)), _Base_key_compare(__comp)
 709           { }
 710 #endif
 711         };
 712
 713       _Rb_tree_impl<_Compare> _M_impl;
 714
 715     protected:
 716       _Base_ptr&
 717       _M_root() _GLIBCXX_NOEXCEPT
 718       { return this->_M_impl._M_header._M_parent; }
 719
 720       _Const_Base_ptr
 721       _M_root() const _GLIBCXX_NOEXCEPT
 722       { return this->_M_impl._M_header._M_parent; }
 723
 724       _Base_ptr&
 725       _M_leftmost() _GLIBCXX_NOEXCEPT
 726       { return this->_M_impl._M_header._M_left; }
 727
 728       _Const_Base_ptr
 729       _M_leftmost() const _GLIBCXX_NOEXCEPT
 730       { return this->_M_impl._M_header._M_left; }
 731
 732       _Base_ptr&
 733       _M_rightmost() _GLIBCXX_NOEXCEPT
 734       { return this->_M_impl._M_header._M_right; }
 735
 736       _Const_Base_ptr
 737       _M_rightmost() const _GLIBCXX_NOEXCEPT
 738       { return this->_M_impl._M_header._M_right; }
 739
 740       _Link_type
 741       _M_begin() _GLIBCXX_NOEXCEPT
 742       { return static_cast<_Link_type>(this->_M_impl._M_header._M_parent); }
 743
 744       _Const_Link_type
 745       _M_begin() const _GLIBCXX_NOEXCEPT
 746       {
 747         return static_cast<_Const_Link_type>
 748           (this->_M_impl._M_header._M_parent);
 749       }
 750
 751       _Base_ptr
 752       _M_end() _GLIBCXX_NOEXCEPT
 753       { return &this->_M_impl._M_header; }
 754
 755       _Const_Base_ptr
 756       _M_end() const _GLIBCXX_NOEXCEPT
 757       { return &this->_M_impl._M_header; }
 758
 759       static const_reference
 760       _S_value(_Const_Link_type __x)
 761       { return *__x->_M_valptr(); }
 762
 763       static const _Key&
 764       _S_key(_Const_Link_type __x)
 765       { return _KeyOfValue()(_S_value(__x)); }
 766
 767       static _Link_type
 768       _S_left(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 769       { return static_cast<_Link_type>(__x->_M_left); }
 770
 771       static _Const_Link_type
 772       _S_left(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 773       { return static_cast<_Const_Link_type>(__x->_M_left); }
 774
 775       static _Link_type
 776       _S_right(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 777       { return static_cast<_Link_type>(__x->_M_right); }
 778
 779       static _Const_Link_type
 780       _S_right(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 781       { return static_cast<_Const_Link_type>(__x->_M_right); }
 782
 783       static const_reference
 784       _S_value(_Const_Base_ptr __x)
 785       { return *static_cast<_Const_Link_type>(__x)->_M_valptr(); }
 786
 787       static const _Key&
 788       _S_key(_Const_Base_ptr __x)
 789       { return _KeyOfValue()(_S_value(__x)); }
 790
 791       static _Base_ptr
 792       _S_minimum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 793       { return _Rb_tree_node_base::_S_minimum(__x); }
 794
 795       static _Const_Base_ptr
 796       _S_minimum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 797       { return _Rb_tree_node_base::_S_minimum(__x); }
 798
 799       static _Base_ptr
 800       _S_maximum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 801       { return _Rb_tree_node_base::_S_maximum(__x); }
 802
 803       static _Const_Base_ptr
 804       _S_maximum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 805       { return _Rb_tree_node_base::_S_maximum(__x); }
 806
 807     public:
 808       typedef _Rb_tree_iterator<value_type>       iterator;
 809       typedef _Rb_tree_const_iterator<value_type> const_iterator;
 810
 811       typedef std::reverse_iterator<iterator>       reverse_iterator;
 812       typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
 813
 814 #if __cplusplus > 201402L
 815       using node_type = _Node_handle<_Key, _Val, _Node_allocator>;
 816       using insert_return_type = _Node_insert_return<
 817         conditional_t<is_same_v<_Key, _Val>, const_iterator, iterator>,
 818         node_type>;
 819 #endif
 820
 821       pair<_Base_ptr, _Base_ptr>
 822       _M_get_insert_unique_pos(const key_type& __k);
 823
 824       pair<_Base_ptr, _Base_ptr>
 825       _M_get_insert_equal_pos(const key_type& __k);
 826
 827       pair<_Base_ptr, _Base_ptr>
 828       _M_get_insert_hint_unique_pos(const_iterator __pos,
 829                                     const key_type& __k);
 830
 831       pair<_Base_ptr, _Base_ptr>
 832       _M_get_insert_hint_equal_pos(const_iterator __pos,
 833                                    const key_type& __k);
 834
 835     private:
 836 #if __cplusplus >= 201103L
 837       template<typename _Arg, typename _NodeGen>
 838         iterator
 839         _M_insert_(_Base_ptr __x, _Base_ptr __y, _Arg&& __v, _NodeGen&);
 840
 841       iterator
 842       _M_insert_node(_Base_ptr __x, _Base_ptr __y, _Link_type __z);
 843
 844       template<typename _Arg>
 845         iterator
 846         _M_insert_lower(_Base_ptr __y, _Arg&& __v);
 847
 848       template<typename _Arg>
 849         iterator
 850         _M_insert_equal_lower(_Arg&& __x);
 851
 852       iterator
 853       _M_insert_lower_node(_Base_ptr __p, _Link_type __z);
 854
 855       iterator
 856       _M_insert_equal_lower_node(_Link_type __z);
 857 #else
 858       template<typename _NodeGen>
 859         iterator
 860         _M_insert_(_Base_ptr __x, _Base_ptr __y,
 861                    const value_type& __v, _NodeGen&);
 862
 863       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 864       // 233. Insertion hints in associative containers.
 865       iterator
 866       _M_insert_lower(_Base_ptr __y, const value_type& __v);
 867
 868       iterator
 869       _M_insert_equal_lower(const value_type& __x);
 870 #endif
 871
 872       template<typename _NodeGen>
 873         _Link_type
 874         _M_copy(_Const_Link_type __x, _Base_ptr __p, _NodeGen&);
 875
 876       template<typename _NodeGen>
 877         _Link_type
 878         _M_copy(const _Rb_tree& __x, _NodeGen& __gen)
 879         {
 880           _Link_type __root = _M_copy(__x._M_begin(), _M_end(), __gen);
 881           _M_leftmost() = _S_minimum(__root);
 882           _M_rightmost() = _S_maximum(__root);
 883           _M_impl._M_node_count = __x._M_impl._M_node_count;
 884           return __root;
 885         }
 886
 887       _Link_type
 888       _M_copy(const _Rb_tree& __x)
 889       {
 890         _Alloc_node __an(*this);
 891         return _M_copy(__x, __an);
 892       }
 893
 894       void
 895       _M_erase(_Link_type __x);
 896
 897       iterator
 898       _M_lower_bound(_Link_type __x, _Base_ptr __y,
 899                      const _Key& __k);
 900
 901       const_iterator
 902       _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 903                      const _Key& __k) const;
 904
 905       iterator
 906       _M_upper_bound(_Link_type __x, _Base_ptr __y,
 907                      const _Key& __k);
 908
 909       const_iterator
 910       _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 911                      const _Key& __k) const;
 912
 913     public:
 914       // allocation/deallocation
 915 #if __cplusplus < 201103L
 916       _Rb_tree() { }
 917 #else
 918       _Rb_tree() = default;
 919 #endif
 920
 921       _Rb_tree(const _Compare& __comp,
 922                const allocator_type& __a = allocator_type())
 923       : _M_impl(__comp, _Node_allocator(__a)) { }
 924
 925       _Rb_tree(const _Rb_tree& __x)
 926       : _M_impl(__x._M_impl)
 927       {
 928         if (__x._M_root() != 0)
 929           _M_root() = _M_copy(__x);
 930       }
 931
 932 #if __cplusplus >= 201103L
 933       _Rb_tree(const allocator_type& __a)
 934       : _M_impl(_Compare(), _Node_allocator(__a))
 935       { }
 936
 937       _Rb_tree(const _Rb_tree& __x, const allocator_type& __a)
 938       : _M_impl(__x._M_impl._M_key_compare, _Node_allocator(__a))
 939       {
 940         if (__x._M_root() != nullptr)
 941           _M_root() = _M_copy(__x);
 942       }
 943
 944       _Rb_tree(_Rb_tree&&) = default;
 945
 946       _Rb_tree(_Rb_tree&& __x, const allocator_type& __a)
 947       : _Rb_tree(std::move(__x), _Node_allocator(__a))
 948       { }
 949
 950       _Rb_tree(_Rb_tree&& __x, _Node_allocator&& __a);
 951 #endif
 952
 953       ~_Rb_tree() _GLIBCXX_NOEXCEPT
 954       { _M_erase(_M_begin()); }
 955
 956       _Rb_tree&
 957       operator=(const _Rb_tree& __x);
 958
 959       // Accessors.
 960       _Compare
 961       key_comp() const
 962       { return _M_impl._M_key_compare; }
 963
 964       iterator
 965       begin() _GLIBCXX_NOEXCEPT
 966       { return iterator(this->_M_impl._M_header._M_left); }
 967
 968       const_iterator
 969       begin() const _GLIBCXX_NOEXCEPT
 970       { return const_iterator(this->_M_impl._M_header._M_left); }
 971
 972       iterator
 973       end() _GLIBCXX_NOEXCEPT
 974       { return iterator(&this->_M_impl._M_header); }
 975
 976       const_iterator
 977       end() const _GLIBCXX_NOEXCEPT
 978       { return const_iterator(&this->_M_impl._M_header); }
 979
 980       reverse_iterator
 981       rbegin() _GLIBCXX_NOEXCEPT
 982       { return reverse_iterator(end()); }
 983
 984       const_reverse_iterator
 985       rbegin() const _GLIBCXX_NOEXCEPT
 986       { return const_reverse_iterator(end()); }
 987
 988       reverse_iterator
 989       rend() _GLIBCXX_NOEXCEPT
 990       { return reverse_iterator(begin()); }
 991
 992       const_reverse_iterator
 993       rend() const _GLIBCXX_NOEXCEPT
 994       { return const_reverse_iterator(begin()); }
 995
 996       bool
 997       empty() const _GLIBCXX_NOEXCEPT
 998       { return _M_impl._M_node_count == 0; }
 999
1000       size_type
1001       size() const _GLIBCXX_NOEXCEPT
1002       { return _M_impl._M_node_count; }
1003
1004       size_type
1005       max_size() const _GLIBCXX_NOEXCEPT
1006       { return _Alloc_traits::max_size(_M_get_Node_allocator()); }
1007
1008       void
1009       swap(_Rb_tree& __t)
1010       _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value);
1011
1012       // Insert/erase.
1013 #if __cplusplus >= 201103L
1014       template<typename _Arg>
1015         pair<iterator, bool>
1016         _M_insert_unique(_Arg&& __x);
1017
1018       template<typename _Arg>
1019         iterator
1020         _M_insert_equal(_Arg&& __x);
1021
1022       template<typename _Arg, typename _NodeGen>
1023         iterator
1024         _M_insert_unique_(const_iterator __pos, _Arg&& __x, _NodeGen&);
1025
1026       template<typename _Arg>
1027         iterator
1028         _M_insert_unique_(const_iterator __pos, _Arg&& __x)
1029         {
1030           _Alloc_node __an(*this);
1031           return _M_insert_unique_(__pos, std::forward<_Arg>(__x), __an);
1032         }
1033
1034       template<typename _Arg, typename _NodeGen>
1035         iterator
1036         _M_insert_equal_(const_iterator __pos, _Arg&& __x, _NodeGen&);
1037
1038       template<typename _Arg>
1039         iterator
1040         _M_insert_equal_(const_iterator __pos, _Arg&& __x)
1041         {
1042           _Alloc_node __an(*this);
1043           return _M_insert_equal_(__pos, std::forward<_Arg>(__x), __an);
1044         }
1045
1046       template<typename... _Args>
1047         pair<iterator, bool>
1048         _M_emplace_unique(_Args&&... __args);
1049
1050       template<typename... _Args>
1051         iterator
1052         _M_emplace_equal(_Args&&... __args);
1053
1054       template<typename... _Args>
1055         iterator
1056         _M_emplace_hint_unique(const_iterator __pos, _Args&&... __args);
1057
1058       template<typename... _Args>
1059         iterator
1060         _M_emplace_hint_equal(const_iterator __pos, _Args&&... __args);
1061 #else
1062       pair<iterator, bool>
1063       _M_insert_unique(const value_type& __x);
1064
1065       iterator
1066       _M_insert_equal(const value_type& __x);
1067
1068       template<typename _NodeGen>
1069         iterator
1070         _M_insert_unique_(const_iterator __pos, const value_type& __x,
1071                           _NodeGen&);
1072
1073       iterator
1074       _M_insert_unique_(const_iterator __pos, const value_type& __x)
1075       {
1076         _Alloc_node __an(*this);
1077         return _M_insert_unique_(__pos, __x, __an);
1078       }
1079
1080       template<typename _NodeGen>
1081         iterator
1082         _M_insert_equal_(const_iterator __pos, const value_type& __x,
1083                          _NodeGen&);
1084       iterator
1085       _M_insert_equal_(const_iterator __pos, const value_type& __x)
1086       {
1087         _Alloc_node __an(*this);
1088         return _M_insert_equal_(__pos, __x, __an);
1089       }
1090 #endif
1091
1092       template<typename _InputIterator>
1093         void
1094         _M_insert_unique(_InputIterator __first, _InputIterator __last);
1095
1096       template<typename _InputIterator>
1097         void
1098         _M_insert_equal(_InputIterator __first, _InputIterator __last);
1099
1100     private:
1101       void
1102       _M_erase_aux(const_iterator __position);
1103
1104       void
1105       _M_erase_aux(const_iterator __first, const_iterator __last);
1106
1107     public:
1108 #if __cplusplus >= 201103L
1109       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1110       // DR 130. Associative erase should return an iterator.
1111       _GLIBCXX_ABI_TAG_CXX11
1112       iterator
1113       erase(const_iterator __position)
1114       {
1115         __glibcxx_assert(__position != end());
1116         const_iterator __result = __position;
1117         ++__result;
1118         _M_erase_aux(__position);
1119         return __result._M_const_cast();
1120       }
1121
1122       // LWG 2059.
1123       _GLIBCXX_ABI_TAG_CXX11
1124       iterator
1125       erase(iterator __position)
1126       {
1127         __glibcxx_assert(__position != end());
1128         iterator __result = __position;
1129         ++__result;
1130         _M_erase_aux(__position);
1131         return __result;
1132       }
1133 #else
1134       void
1135       erase(iterator __position)
1136       {
1137         __glibcxx_assert(__position != end());
1138         _M_erase_aux(__position);
1139       }
1140
1141       void
1142       erase(const_iterator __position)
1143       {
1144         __glibcxx_assert(__position != end());
1145         _M_erase_aux(__position);
1146       }
1147 #endif
1148       size_type
1149       erase(const key_type& __x);
1150
1151 #if __cplusplus >= 201103L
1152       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1153       // DR 130. Associative erase should return an iterator.
1154       _GLIBCXX_ABI_TAG_CXX11
1155       iterator
1156       erase(const_iterator __first, const_iterator __last)
1157       {
1158         _M_erase_aux(__first, __last);
1159         return __last._M_const_cast();
1160       }
1161 #else
1162       void
1163       erase(iterator __first, iterator __last)
1164       { _M_erase_aux(__first, __last); }
1165
1166       void
1167       erase(const_iterator __first, const_iterator __last)
1168       { _M_erase_aux(__first, __last); }
1169 #endif
1170       void
1171       erase(const key_type* __first, const key_type* __last);
1172
1173       void
1174       clear() _GLIBCXX_NOEXCEPT
1175       {
1176         _M_erase(_M_begin());
1177         _M_impl._M_reset();
1178       }
1179
1180       // Set operations.
1181       iterator
1182       find(const key_type& __k);
1183
1184       const_iterator
1185       find(const key_type& __k) const;
1186
1187       size_type
1188       count(const key_type& __k) const;
1189
1190       iterator
1191       lower_bound(const key_type& __k)
1192       { return _M_lower_bound(_M_begin(), _M_end(), __k); }
1193
1194       const_iterator
1195       lower_bound(const key_type& __k) const
1196       { return _M_lower_bound(_M_begin(), _M_end(), __k); }
1197
1198       iterator
1199       upper_bound(const key_type& __k)
1200       { return _M_upper_bound(_M_begin(), _M_end(), __k); }
1201
1202       const_iterator
1203       upper_bound(const key_type& __k) const
1204       { return _M_upper_bound(_M_begin(), _M_end(), __k); }
1205
1206       pair<iterator, iterator>
1207       equal_range(const key_type& __k);
1208
1209       pair<const_iterator, const_iterator>
1210       equal_range(const key_type& __k) const;
1211
1212 #if __cplusplus > 201103L
1213       template<typename _Kt,
1214                typename _Req =
1215                  typename __has_is_transparent<_Compare, _Kt>::type>
1216         iterator
1217         _M_find_tr(const _Kt& __k)
1218         {
1219           const _Rb_tree* __const_this = this;
1220           return __const_this->_M_find_tr(__k)._M_const_cast();
1221         }
1222
1223       template<typename _Kt,
1224                typename _Req =
1225                  typename __has_is_transparent<_Compare, _Kt>::type>
1226         const_iterator
1227         _M_find_tr(const _Kt& __k) const
1228         {
1229           auto __j = _M_lower_bound_tr(__k);
1230           if (__j != end() && _M_impl._M_key_compare(__k, _S_key(__j._M_node)))
1231             __j = end();
1232           return __j;
1233         }
1234
1235       template<typename _Kt,
1236                typename _Req =
1237                  typename __has_is_transparent<_Compare, _Kt>::type>
1238         size_type
1239         _M_count_tr(const _Kt& __k) const
1240         {
1241           auto __p = _M_equal_range_tr(__k);
1242           return std::distance(__p.first, __p.second);
1243         }
1244
1245       template<typename _Kt,
1246                typename _Req =
1247                  typename __has_is_transparent<_Compare, _Kt>::type>
1248         iterator
1249         _M_lower_bound_tr(const _Kt& __k)
1250         {
1251           const _Rb_tree* __const_this = this;
1252           return __const_this->_M_lower_bound_tr(__k)._M_const_cast();
1253         }
1254
1255       template<typename _Kt,
1256                typename _Req =
1257                  typename __has_is_transparent<_Compare, _Kt>::type>
1258         const_iterator
1259         _M_lower_bound_tr(const _Kt& __k) const
1260         {
1261           auto __x = _M_begin();
1262           auto __y = _M_end();
1263           while (__x != 0)
1264             if (!_M_impl._M_key_compare(_S_key(__x), __k))
1265               {
1266                 __y = __x;
1267                 __x = _S_left(__x);
1268               }
1269             else
1270               __x = _S_right(__x);
1271           return const_iterator(__y);
1272         }
1273
1274       template<typename _Kt,
1275                typename _Req =
1276                  typename __has_is_transparent<_Compare, _Kt>::type>
1277         iterator
1278         _M_upper_bound_tr(const _Kt& __k)
1279         {
1280           const _Rb_tree* __const_this = this;
1281           return __const_this->_M_upper_bound_tr(__k)._M_const_cast();
1282         }
1283
1284       template<typename _Kt,
1285                typename _Req =
1286                  typename __has_is_transparent<_Compare, _Kt>::type>
1287         const_iterator
1288         _M_upper_bound_tr(const _Kt& __k) const
1289         {
1290           auto __x = _M_begin();
1291           auto __y = _M_end();
1292           while (__x != 0)
1293             if (_M_impl._M_key_compare(__k, _S_key(__x)))
1294               {
1295                 __y = __x;
1296                 __x = _S_left(__x);
1297               }
1298             else
1299               __x = _S_right(__x);
1300           return const_iterator(__y);
1301         }
1302
1303       template<typename _Kt,
1304                typename _Req =
1305                  typename __has_is_transparent<_Compare, _Kt>::type>
1306         pair<iterator, iterator>
1307         _M_equal_range_tr(const _Kt& __k)
1308         {
1309           const _Rb_tree* __const_this = this;
1310           auto __ret = __const_this->_M_equal_range_tr(__k);
1311           return { __ret.first._M_const_cast(), __ret.second._M_const_cast() };
1312         }
1313
1314       template<typename _Kt,
1315                typename _Req =
1316                  typename __has_is_transparent<_Compare, _Kt>::type>
1317         pair<const_iterator, const_iterator>
1318         _M_equal_range_tr(const _Kt& __k) const
1319         {
1320           auto __low = _M_lower_bound_tr(__k);
1321           auto __high = __low;
1322           auto& __cmp = _M_impl._M_key_compare;
1323           while (__high != end() && !__cmp(__k, _S_key(__high._M_node)))
1324             ++__high;
1325           return { __low, __high };
1326         }
1327 #endif
1328
1329       // Debugging.
1330       bool
1331       __rb_verify() const;
1332
1333 #if __cplusplus >= 201103L
1334       _Rb_tree&
1335       operator=(_Rb_tree&&)
1336       noexcept(_Alloc_traits::_S_nothrow_move()
1337                && is_nothrow_move_assignable<_Compare>::value);
1338
1339       template<typename _Iterator>
1340         void
1341         _M_assign_unique(_Iterator, _Iterator);
1342
1343       template<typename _Iterator>
1344         void
1345         _M_assign_equal(_Iterator, _Iterator);
1346
1347     private:
1348       // Move elements from container with equal allocator.
1349       void
1350       _M_move_data(_Rb_tree& __x, std::true_type)
1351       { _M_impl._M_move_data(__x._M_impl); }
1352
1353       // Move elements from container with possibly non-equal allocator,
1354       // which might result in a copy not a move.
1355       void
1356       _M_move_data(_Rb_tree&, std::false_type);
1357
1358       // Move assignment from container with equal allocator.
1359       void
1360       _M_move_assign(_Rb_tree&, std::true_type);
1361
1362       // Move assignment from container with possibly non-equal allocator,
1363       // which might result in a copy not a move.
1364       void
1365       _M_move_assign(_Rb_tree&, std::false_type);
1366 #endif
1367
1368 #if __cplusplus > 201402L
1369     public:
1370       /// Re-insert an extracted node.
1371       insert_return_type
1372       _M_reinsert_node_unique(node_type&& __nh)
1373       {
1374         insert_return_type __ret;
1375         if (__nh.empty())
1376           __ret.position = end();
1377         else
1378           {
1379             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1380
1381             auto __res = _M_get_insert_unique_pos(__nh._M_key());
1382             if (__res.second)
1383               {
1384                 __ret.position
1385                   = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1386                 __nh._M_ptr = nullptr;
1387                 __ret.inserted = true;
1388               }
1389             else
1390               {
1391                 __ret.node = std::move(__nh);
1392                 __ret.position = iterator(__res.first);
1393                 __ret.inserted = false;
1394               }
1395           }
1396         return __ret;
1397       }
1398
1399       /// Re-insert an extracted node.
1400       iterator
1401       _M_reinsert_node_equal(node_type&& __nh)
1402       {
1403         iterator __ret;
1404         if (__nh.empty())
1405           __ret = end();
1406         else
1407           {
1408             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1409             auto __res = _M_get_insert_equal_pos(__nh._M_key());
1410             if (__res.second)
1411               __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1412             else
1413               __ret = _M_insert_equal_lower_node(__nh._M_ptr);
1414             __nh._M_ptr = nullptr;
1415           }
1416         return __ret;
1417       }
1418
1419       /// Re-insert an extracted node.
1420       iterator
1421       _M_reinsert_node_hint_unique(const_iterator __hint, node_type&& __nh)
1422       {
1423         iterator __ret;
1424         if (__nh.empty())
1425           __ret = end();
1426         else
1427           {
1428             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1429             auto __res = _M_get_insert_hint_unique_pos(__hint, __nh._M_key());
1430             if (__res.second)
1431               {
1432                 __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1433                 __nh._M_ptr = nullptr;
1434               }
1435             else
1436               __ret = iterator(__res.first);
1437           }
1438         return __ret;
1439       }
1440
1441       /// Re-insert an extracted node.
1442       iterator
1443       _M_reinsert_node_hint_equal(const_iterator __hint, node_type&& __nh)
1444       {
1445         iterator __ret;
1446         if (__nh.empty())
1447           __ret = end();
1448         else
1449           {
1450             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1451             auto __res = _M_get_insert_hint_equal_pos(__hint, __nh._M_key());
1452             if (__res.second)
1453               __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1454             else
1455               __ret = _M_insert_equal_lower_node(__nh._M_ptr);
1456             __nh._M_ptr = nullptr;
1457           }
1458         return __ret;
1459       }
1460
1461       /// Extract a node.
1462       node_type
1463       extract(const_iterator __pos)
1464       {
1465         auto __ptr = _Rb_tree_rebalance_for_erase(
1466             __pos._M_const_cast()._M_node, _M_impl._M_header);
1467         --_M_impl._M_node_count;
1468         return { static_cast<_Link_type>(__ptr), _M_get_Node_allocator() };
1469       }
1470
1471       /// Extract a node.
1472       node_type
1473       extract(const key_type& __k)
1474       {
1475         node_type __nh;
1476         auto __pos = find(__k);
1477         if (__pos != end())
1478           __nh = extract(const_iterator(__pos));
1479         return __nh;
1480       }
1481
1482       template<typename _Compare2>
1483         using _Compatible_tree
1484           = _Rb_tree<_Key, _Val, _KeyOfValue, _Compare2, _Alloc>;
1485
1486       template<typename, typename>
1487         friend class _Rb_tree_merge_helper;
1488
1489       /// Merge from a compatible container into one with unique keys.
1490       template<typename _Compare2>
1491         void
1492         _M_merge_unique(_Compatible_tree<_Compare2>& __src) noexcept
1493         {
1494           using _Merge_helper = _Rb_tree_merge_helper<_Rb_tree, _Compare2>;
1495           for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1496             {
1497               auto __pos = __i++;
1498               auto __res = _M_get_insert_unique_pos(_KeyOfValue()(*__pos));
1499               if (__res.second)
1500                 {
1501                   auto& __src_impl = _Merge_helper::_S_get_impl(__src);
1502                   auto __ptr = _Rb_tree_rebalance_for_erase(
1503                       __pos._M_node, __src_impl._M_header);
1504                   --__src_impl._M_node_count;
1505                   _M_insert_node(__res.first, __res.second,
1506                                  static_cast<_Link_type>(__ptr));
1507                 }
1508             }
1509         }
1510
1511       /// Merge from a compatible container into one with equivalent keys.
1512       template<typename _Compare2>
1513         void
1514         _M_merge_equal(_Compatible_tree<_Compare2>& __src) noexcept
1515         {
1516           using _Merge_helper = _Rb_tree_merge_helper<_Rb_tree, _Compare2>;
1517           for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1518             {
1519               auto __pos = __i++;
1520               auto __res = _M_get_insert_equal_pos(_KeyOfValue()(*__pos));
1521               if (__res.second)
1522                 {
1523                   auto& __src_impl = _Merge_helper::_S_get_impl(__src);
1524                   auto __ptr = _Rb_tree_rebalance_for_erase(
1525                       __pos._M_node, __src_impl._M_header);
1526                   --__src_impl._M_node_count;
1527                   _M_insert_node(__res.first, __res.second,
1528                                  static_cast<_Link_type>(__ptr));
1529                 }
1530             }
1531         }
1532 #endif // C++17
1533     };
1534
1535   template<typename _Key, typename _Val, typename _KeyOfValue,
1536            typename _Compare, typename _Alloc>
1537     inline bool
1538     operator==(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1539                const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1540     {
1541       return __x.size() == __y.size()
1542              && std::equal(__x.begin(), __x.end(), __y.begin());
1543     }
1544
1545   template<typename _Key, typename _Val, typename _KeyOfValue,
1546            typename _Compare, typename _Alloc>
1547     inline bool
1548     operator<(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1549               const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1550     {
1551       return std::lexicographical_compare(__x.begin(), __x.end(),
1552                                           __y.begin(), __y.end());
1553     }
1554
1555   template<typename _Key, typename _Val, typename _KeyOfValue,
1556            typename _Compare, typename _Alloc>
1557     inline bool
1558     operator!=(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1559                const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1560     { return !(__x == __y); }
1561
1562   template<typename _Key, typename _Val, typename _KeyOfValue,
1563            typename _Compare, typename _Alloc>
1564     inline bool
1565     operator>(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1566               const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1567     { return __y < __x; }
1568
1569   template<typename _Key, typename _Val, typename _KeyOfValue,
1570            typename _Compare, typename _Alloc>
1571     inline bool
1572     operator<=(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1573                const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1574     { return !(__y < __x); }
1575
1576   template<typename _Key, typename _Val, typename _KeyOfValue,
1577            typename _Compare, typename _Alloc>
1578     inline bool
1579     operator>=(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1580                const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1581     { return !(__x < __y); }
1582
1583   template<typename _Key, typename _Val, typename _KeyOfValue,
1584            typename _Compare, typename _Alloc>
1585     inline void
1586     swap(_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1587          _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1588     { __x.swap(__y); }
1589
1590 #if __cplusplus >= 201103L
1591   template<typename _Key, typename _Val, typename _KeyOfValue,
1592            typename _Compare, typename _Alloc>
1593     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1594     _Rb_tree(_Rb_tree&& __x, _Node_allocator&& __a)
1595     : _M_impl(__x._M_impl._M_key_compare, std::move(__a))
1596     {
1597       using __eq = typename _Alloc_traits::is_always_equal;
1598       if (__x._M_root() != nullptr)
1599         _M_move_data(__x, __eq());
1600     }
1601
1602   template<typename _Key, typename _Val, typename _KeyOfValue,
1603            typename _Compare, typename _Alloc>
1604     void
1605     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1606     _M_move_data(_Rb_tree& __x, std::false_type)
1607     {
1608       if (_M_get_Node_allocator() == __x._M_get_Node_allocator())
1609         _M_move_data(__x, std::true_type());
1610       else
1611         {
1612           _Alloc_node __an(*this);
1613           auto __lbd =
1614             [&__an](const value_type& __cval)
1615             {
1616               auto& __val = const_cast<value_type&>(__cval);
1617               return __an(std::move_if_noexcept(__val));
1618             };
1619           _M_root() = _M_copy(__x, __lbd);
1620         }
1621     }
1622
1623   template<typename _Key, typename _Val, typename _KeyOfValue,
1624            typename _Compare, typename _Alloc>
1625     inline void
1626     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1627     _M_move_assign(_Rb_tree& __x, true_type)
1628     {
1629       clear();
1630       if (__x._M_root() != nullptr)
1631         _M_move_data(__x, std::true_type());
1632       std::__alloc_on_move(_M_get_Node_allocator(),
1633                            __x._M_get_Node_allocator());
1634     }
1635
1636   template<typename _Key, typename _Val, typename _KeyOfValue,
1637            typename _Compare, typename _Alloc>
1638     void
1639     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1640     _M_move_assign(_Rb_tree& __x, false_type)
1641     {
1642       if (_M_get_Node_allocator() == __x._M_get_Node_allocator())
1643         return _M_move_assign(__x, true_type{});
1644
1645       // Try to move each node reusing existing nodes and copying __x nodes
1646       // structure.
1647       _Reuse_or_alloc_node __roan(*this);
1648       _M_impl._M_reset();
1649       if (__x._M_root() != nullptr)
1650         {
1651           auto __lbd =
1652             [&__roan](const value_type& __cval)
1653             {
1654               auto& __val = const_cast<value_type&>(__cval);
1655               return __roan(std::move_if_noexcept(__val));
1656             };
1657           _M_root() = _M_copy(__x, __lbd);
1658           __x.clear();
1659         }
1660     }
1661
1662   template<typename _Key, typename _Val, typename _KeyOfValue,
1663            typename _Compare, typename _Alloc>
1664     inline _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&
1665     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1666     operator=(_Rb_tree&& __x)
1667     noexcept(_Alloc_traits::_S_nothrow_move()
1668              && is_nothrow_move_assignable<_Compare>::value)
1669     {
1670       _M_impl._M_key_compare = std::move(__x._M_impl._M_key_compare);
1671       _M_move_assign(__x, __bool_constant<_Alloc_traits::_S_nothrow_move()>());
1672       return *this;
1673     }
1674
1675   template<typename _Key, typename _Val, typename _KeyOfValue,
1676            typename _Compare, typename _Alloc>
1677     template<typename _Iterator>
1678       void
1679       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1680       _M_assign_unique(_Iterator __first, _Iterator __last)
1681       {
1682         _Reuse_or_alloc_node __roan(*this);
1683         _M_impl._M_reset();
1684         for (; __first != __last; ++__first)
1685           _M_insert_unique_(end(), *__first, __roan);
1686       }
1687
1688   template<typename _Key, typename _Val, typename _KeyOfValue,
1689            typename _Compare, typename _Alloc>
1690     template<typename _Iterator>
1691       void
1692       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1693       _M_assign_equal(_Iterator __first, _Iterator __last)
1694       {
1695         _Reuse_or_alloc_node __roan(*this);
1696         _M_impl._M_reset();
1697         for (; __first != __last; ++__first)
1698           _M_insert_equal_(end(), *__first, __roan);
1699       }
1700 #endif
1701
1702   template<typename _Key, typename _Val, typename _KeyOfValue,
1703            typename _Compare, typename _Alloc>
1704     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&
1705     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1706     operator=(const _Rb_tree& __x)
1707     {
1708       if (this != &__x)
1709         {
1710           // Note that _Key may be a constant type.
1711 #if __cplusplus >= 201103L
1712           if (_Alloc_traits::_S_propagate_on_copy_assign())
1713             {
1714               auto& __this_alloc = this->_M_get_Node_allocator();
1715               auto& __that_alloc = __x._M_get_Node_allocator();
1716               if (!_Alloc_traits::_S_always_equal()
1717                   && __this_alloc != __that_alloc)
1718                 {
1719                   // Replacement allocator cannot free existing storage, we need
1720                   // to erase nodes first.
1721                   clear();
1722                   std::__alloc_on_copy(__this_alloc, __that_alloc);
1723                 }
1724             }
1725 #endif
1726
1727           _Reuse_or_alloc_node __roan(*this);
1728           _M_impl._M_reset();
1729           _M_impl._M_key_compare = __x._M_impl._M_key_compare;
1730           if (__x._M_root() != 0)
1731             _M_root() = _M_copy(__x, __roan);
1732         }
1733
1734       return *this;
1735     }
1736
1737   template<typename _Key, typename _Val, typename _KeyOfValue,
1738            typename _Compare, typename _Alloc>
1739 #if __cplusplus >= 201103L
1740     template<typename _Arg, typename _NodeGen>
1741 #else
1742     template<typename _NodeGen>
1743 #endif
1744       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1745       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1746       _M_insert_(_Base_ptr __x, _Base_ptr __p,
1747 #if __cplusplus >= 201103L
1748                  _Arg&& __v,
1749 #else
1750                  const _Val& __v,
1751 #endif
1752                  _NodeGen& __node_gen)
1753       {
1754         bool __insert_left = (__x != 0 || __p == _M_end()
1755                               || _M_impl._M_key_compare(_KeyOfValue()(__v),
1756                                                         _S_key(__p)));
1757
1758         _Link_type __z = __node_gen(_GLIBCXX_FORWARD(_Arg, __v));
1759
1760         _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
1761                                       this->_M_impl._M_header);
1762         ++_M_impl._M_node_count;
1763         return iterator(__z);
1764       }
1765
1766   template<typename _Key, typename _Val, typename _KeyOfValue,
1767            typename _Compare, typename _Alloc>
1768 #if __cplusplus >= 201103L
1769     template<typename _Arg>
1770 #endif
1771     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1772     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1773 #if __cplusplus >= 201103L
1774     _M_insert_lower(_Base_ptr __p, _Arg&& __v)
1775 #else
1776     _M_insert_lower(_Base_ptr __p, const _Val& __v)
1777 #endif
1778     {
1779       bool __insert_left = (__p == _M_end()
1780                             || !_M_impl._M_key_compare(_S_key(__p),
1781                                                        _KeyOfValue()(__v)));
1782
1783       _Link_type __z = _M_create_node(_GLIBCXX_FORWARD(_Arg, __v));
1784
1785       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
1786                                     this->_M_impl._M_header);
1787       ++_M_impl._M_node_count;
1788       return iterator(__z);
1789     }
1790
1791   template<typename _Key, typename _Val, typename _KeyOfValue,
1792            typename _Compare, typename _Alloc>
1793 #if __cplusplus >= 201103L
1794     template<typename _Arg>
1795 #endif
1796     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1797     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1798 #if __cplusplus >= 201103L
1799     _M_insert_equal_lower(_Arg&& __v)
1800 #else
1801     _M_insert_equal_lower(const _Val& __v)
1802 #endif
1803     {
1804       _Link_type __x = _M_begin();
1805       _Base_ptr __y = _M_end();
1806       while (__x != 0)
1807         {
1808           __y = __x;
1809           __x = !_M_impl._M_key_compare(_S_key(__x), _KeyOfValue()(__v)) ?
1810                 _S_left(__x) : _S_right(__x);
1811         }
1812       return _M_insert_lower(__y, _GLIBCXX_FORWARD(_Arg, __v));
1813     }
1814
1815   template<typename _Key, typename _Val, typename _KoV,
1816            typename _Compare, typename _Alloc>
1817     template<typename _NodeGen>
1818       typename _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::_Link_type
1819       _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::
1820       _M_copy(_Const_Link_type __x, _Base_ptr __p, _NodeGen& __node_gen)
1821       {
1822         // Structural copy. __x and __p must be non-null.
1823         _Link_type __top = _M_clone_node(__x, __node_gen);
1824         __top->_M_parent = __p;
1825
1826         __try
1827           {
1828             if (__x->_M_right)
1829               __top->_M_right = _M_copy(_S_right(__x), __top, __node_gen);
1830             __p = __top;
1831             __x = _S_left(__x);
1832
1833             while (__x != 0)
1834               {
1835                 _Link_type __y = _M_clone_node(__x, __node_gen);
1836                 __p->_M_left = __y;
1837                 __y->_M_parent = __p;
1838                 if (__x->_M_right)
1839                   __y->_M_right = _M_copy(_S_right(__x), __y, __node_gen);
1840                 __p = __y;
1841                 __x = _S_left(__x);
1842               }
1843           }
1844         __catch(...)
1845           {
1846             _M_erase(__top);
1847             __throw_exception_again;
1848           }
1849         return __top;
1850       }
1851
1852   template<typename _Key, typename _Val, typename _KeyOfValue,
1853            typename _Compare, typename _Alloc>
1854     void
1855     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1856     _M_erase(_Link_type __x)
1857     {
1858       // Erase without rebalancing.
1859       while (__x != 0)
1860         {
1861           _M_erase(_S_right(__x));
1862           _Link_type __y = _S_left(__x);
1863           _M_drop_node(__x);
1864           __x = __y;
1865         }
1866     }
1867
1868   template<typename _Key, typename _Val, typename _KeyOfValue,
1869            typename _Compare, typename _Alloc>
1870     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1871                       _Compare, _Alloc>::iterator
1872     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1873     _M_lower_bound(_Link_type __x, _Base_ptr __y,
1874                    const _Key& __k)
1875     {
1876       while (__x != 0)
1877         if (!_M_impl._M_key_compare(_S_key(__x), __k))
1878           __y = __x, __x = _S_left(__x);
1879         else
1880           __x = _S_right(__x);
1881       return iterator(__y);
1882     }
1883
1884   template<typename _Key, typename _Val, typename _KeyOfValue,
1885            typename _Compare, typename _Alloc>
1886     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1887                       _Compare, _Alloc>::const_iterator
1888     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1889     _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
1890                    const _Key& __k) const
1891     {
1892       while (__x != 0)
1893         if (!_M_impl._M_key_compare(_S_key(__x), __k))
1894           __y = __x, __x = _S_left(__x);
1895         else
1896           __x = _S_right(__x);
1897       return const_iterator(__y);
1898     }
1899
1900   template<typename _Key, typename _Val, typename _KeyOfValue,
1901            typename _Compare, typename _Alloc>
1902     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1903                       _Compare, _Alloc>::iterator
1904     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1905     _M_upper_bound(_Link_type __x, _Base_ptr __y,
1906                    const _Key& __k)
1907     {
1908       while (__x != 0)
1909         if (_M_impl._M_key_compare(__k, _S_key(__x)))
1910           __y = __x, __x = _S_left(__x);
1911         else
1912           __x = _S_right(__x);
1913       return iterator(__y);
1914     }
1915
1916   template<typename _Key, typename _Val, typename _KeyOfValue,
1917            typename _Compare, typename _Alloc>
1918     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1919                       _Compare, _Alloc>::const_iterator
1920     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1921     _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
1922                    const _Key& __k) const
1923     {
1924       while (__x != 0)
1925         if (_M_impl._M_key_compare(__k, _S_key(__x)))
1926           __y = __x, __x = _S_left(__x);
1927         else
1928           __x = _S_right(__x);
1929       return const_iterator(__y);
1930     }
1931
1932   template<typename _Key, typename _Val, typename _KeyOfValue,
1933            typename _Compare, typename _Alloc>
1934     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
1935                            _Compare, _Alloc>::iterator,
1936          typename _Rb_tree<_Key, _Val, _KeyOfValue,
1937                            _Compare, _Alloc>::iterator>
1938     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1939     equal_range(const _Key& __k)
1940     {
1941       _Link_type __x = _M_begin();
1942       _Base_ptr __y = _M_end();
1943       while (__x != 0)
1944         {
1945           if (_M_impl._M_key_compare(_S_key(__x), __k))
1946             __x = _S_right(__x);
1947           else if (_M_impl._M_key_compare(__k, _S_key(__x)))
1948             __y = __x, __x = _S_left(__x);
1949           else
1950             {
1951               _Link_type __xu(__x);
1952               _Base_ptr __yu(__y);
1953               __y = __x, __x = _S_left(__x);
1954               __xu = _S_right(__xu);
1955               return pair<iterator,
1956                           iterator>(_M_lower_bound(__x, __y, __k),
1957                                     _M_upper_bound(__xu, __yu, __k));
1958             }
1959         }
1960       return pair<iterator, iterator>(iterator(__y),
1961                                       iterator(__y));
1962     }
1963
1964   template<typename _Key, typename _Val, typename _KeyOfValue,
1965            typename _Compare, typename _Alloc>
1966     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
1967                            _Compare, _Alloc>::const_iterator,
1968          typename _Rb_tree<_Key, _Val, _KeyOfValue,
1969                            _Compare, _Alloc>::const_iterator>
1970     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1971     equal_range(const _Key& __k) const
1972     {
1973       _Const_Link_type __x = _M_begin();
1974       _Const_Base_ptr __y = _M_end();
1975       while (__x != 0)
1976         {
1977           if (_M_impl._M_key_compare(_S_key(__x), __k))
1978             __x = _S_right(__x);
1979           else if (_M_impl._M_key_compare(__k, _S_key(__x)))
1980             __y = __x, __x = _S_left(__x);
1981           else
1982             {
1983               _Const_Link_type __xu(__x);
1984               _Const_Base_ptr __yu(__y);
1985               __y = __x, __x = _S_left(__x);
1986               __xu = _S_right(__xu);
1987               return pair<const_iterator,
1988                           const_iterator>(_M_lower_bound(__x, __y, __k),
1989                                           _M_upper_bound(__xu, __yu, __k));
1990             }
1991         }
1992       return pair<const_iterator, const_iterator>(const_iterator(__y),
1993                                                   const_iterator(__y));
1994     }
1995
1996   template<typename _Key, typename _Val, typename _KeyOfValue,
1997            typename _Compare, typename _Alloc>
1998     void
1999     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2000     swap(_Rb_tree& __t)
2001     _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
2002     {
2003       if (_M_root() == 0)
2004         {
2005           if (__t._M_root() != 0)
2006             _M_impl._M_move_data(__t._M_impl);
2007         }
2008       else if (__t._M_root() == 0)
2009         __t._M_impl._M_move_data(_M_impl);
2010       else
2011         {
2012           std::swap(_M_root(),__t._M_root());
2013           std::swap(_M_leftmost(),__t._M_leftmost());
2014           std::swap(_M_rightmost(),__t._M_rightmost());
2015
2016           _M_root()->_M_parent = _M_end();
2017           __t._M_root()->_M_parent = __t._M_end();
2018           std::swap(this->_M_impl._M_node_count, __t._M_impl._M_node_count);
2019         }
2020       // No need to swap header's color as it does not change.
2021       std::swap(this->_M_impl._M_key_compare, __t._M_impl._M_key_compare);
2022
2023       _Alloc_traits::_S_on_swap(_M_get_Node_allocator(),
2024                                 __t._M_get_Node_allocator());
2025     }
2026
2027   template<typename _Key, typename _Val, typename _KeyOfValue,
2028            typename _Compare, typename _Alloc>
2029     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2030                            _Compare, _Alloc>::_Base_ptr,
2031          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2032                            _Compare, _Alloc>::_Base_ptr>
2033     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2034     _M_get_insert_unique_pos(const key_type& __k)
2035     {
2036       typedef pair<_Base_ptr, _Base_ptr> _Res;
2037       _Link_type __x = _M_begin();
2038       _Base_ptr __y = _M_end();
2039       bool __comp = true;
2040       while (__x != 0)
2041         {
2042           __y = __x;
2043           __comp = _M_impl._M_key_compare(__k, _S_key(__x));
2044           __x = __comp ? _S_left(__x) : _S_right(__x);
2045         }
2046       iterator __j = iterator(__y);
2047       if (__comp)
2048         {
2049           if (__j == begin())
2050             return _Res(__x, __y);
2051           else
2052             --__j;
2053         }
2054       if (_M_impl._M_key_compare(_S_key(__j._M_node), __k))
2055         return _Res(__x, __y);
2056       return _Res(__j._M_node, 0);
2057     }
2058
2059   template<typename _Key, typename _Val, typename _KeyOfValue,
2060            typename _Compare, typename _Alloc>
2061     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2062                            _Compare, _Alloc>::_Base_ptr,
2063          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2064                            _Compare, _Alloc>::_Base_ptr>
2065     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2066     _M_get_insert_equal_pos(const key_type& __k)
2067     {
2068       typedef pair<_Base_ptr, _Base_ptr> _Res;
2069       _Link_type __x = _M_begin();
2070       _Base_ptr __y = _M_end();
2071       while (__x != 0)
2072         {
2073           __y = __x;
2074           __x = _M_impl._M_key_compare(__k, _S_key(__x)) ?
2075                 _S_left(__x) : _S_right(__x);
2076         }
2077       return _Res(__x, __y);
2078     }
2079
2080   template<typename _Key, typename _Val, typename _KeyOfValue,
2081            typename _Compare, typename _Alloc>
2082 #if __cplusplus >= 201103L
2083     template<typename _Arg>
2084 #endif
2085     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2086                            _Compare, _Alloc>::iterator, bool>
2087     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2088 #if __cplusplus >= 201103L
2089     _M_insert_unique(_Arg&& __v)
2090 #else
2091     _M_insert_unique(const _Val& __v)
2092 #endif
2093     {
2094       typedef pair<iterator, bool> _Res;
2095       pair<_Base_ptr, _Base_ptr> __res
2096         = _M_get_insert_unique_pos(_KeyOfValue()(__v));
2097
2098       if (__res.second)
2099         {
2100           _Alloc_node __an(*this);
2101           return _Res(_M_insert_(__res.first, __res.second,
2102                                  _GLIBCXX_FORWARD(_Arg, __v), __an),
2103                       true);
2104         }
2105
2106       return _Res(iterator(__res.first), false);
2107     }
2108
2109   template<typename _Key, typename _Val, typename _KeyOfValue,
2110            typename _Compare, typename _Alloc>
2111 #if __cplusplus >= 201103L
2112     template<typename _Arg>
2113 #endif
2114     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2115     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2116 #if __cplusplus >= 201103L
2117     _M_insert_equal(_Arg&& __v)
2118 #else
2119     _M_insert_equal(const _Val& __v)
2120 #endif
2121     {
2122       pair<_Base_ptr, _Base_ptr> __res
2123         = _M_get_insert_equal_pos(_KeyOfValue()(__v));
2124       _Alloc_node __an(*this);
2125       return _M_insert_(__res.first, __res.second,
2126                         _GLIBCXX_FORWARD(_Arg, __v), __an);
2127     }
2128
2129   template<typename _Key, typename _Val, typename _KeyOfValue,
2130            typename _Compare, typename _Alloc>
2131     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2132                            _Compare, _Alloc>::_Base_ptr,
2133          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2134                            _Compare, _Alloc>::_Base_ptr>
2135     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2136     _M_get_insert_hint_unique_pos(const_iterator __position,
2137                                   const key_type& __k)
2138     {
2139       iterator __pos = __position._M_const_cast();
2140       typedef pair<_Base_ptr, _Base_ptr> _Res;
2141
2142       // end()
2143       if (__pos._M_node == _M_end())
2144         {
2145           if (size() > 0
2146               && _M_impl._M_key_compare(_S_key(_M_rightmost()), __k))
2147             return _Res(0, _M_rightmost());
2148           else
2149             return _M_get_insert_unique_pos(__k);
2150         }
2151       else if (_M_impl._M_key_compare(__k, _S_key(__pos._M_node)))
2152         {
2153           // First, try before...
2154           iterator __before = __pos;
2155           if (__pos._M_node == _M_leftmost()) // begin()
2156             return _Res(_M_leftmost(), _M_leftmost());
2157           else if (_M_impl._M_key_compare(_S_key((--__before)._M_node), __k))
2158             {
2159               if (_S_right(__before._M_node) == 0)
2160                 return _Res(0, __before._M_node);
2161               else
2162                 return _Res(__pos._M_node, __pos._M_node);
2163             }
2164           else
2165             return _M_get_insert_unique_pos(__k);
2166         }
2167       else if (_M_impl._M_key_compare(_S_key(__pos._M_node), __k))
2168         {
2169           // ... then try after.
2170           iterator __after = __pos;
2171           if (__pos._M_node == _M_rightmost())
2172             return _Res(0, _M_rightmost());
2173           else if (_M_impl._M_key_compare(__k, _S_key((++__after)._M_node)))
2174             {
2175               if (_S_right(__pos._M_node) == 0)
2176                 return _Res(0, __pos._M_node);
2177               else
2178                 return _Res(__after._M_node, __after._M_node);
2179             }
2180           else
2181             return _M_get_insert_unique_pos(__k);
2182         }
2183       else
2184         // Equivalent keys.
2185         return _Res(__pos._M_node, 0);
2186     }
2187
2188   template<typename _Key, typename _Val, typename _KeyOfValue,
2189            typename _Compare, typename _Alloc>
2190 #if __cplusplus >= 201103L
2191     template<typename _Arg, typename _NodeGen>
2192 #else
2193     template<typename _NodeGen>
2194 #endif
2195       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2196       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2197       _M_insert_unique_(const_iterator __position,
2198 #if __cplusplus >= 201103L
2199                         _Arg&& __v,
2200 #else
2201                         const _Val& __v,
2202 #endif
2203                         _NodeGen& __node_gen)
2204     {
2205       pair<_Base_ptr, _Base_ptr> __res
2206         = _M_get_insert_hint_unique_pos(__position, _KeyOfValue()(__v));
2207
2208       if (__res.second)
2209         return _M_insert_(__res.first, __res.second,
2210                           _GLIBCXX_FORWARD(_Arg, __v),
2211                           __node_gen);
2212       return iterator(__res.first);
2213     }
2214
2215   template<typename _Key, typename _Val, typename _KeyOfValue,
2216            typename _Compare, typename _Alloc>
2217     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2218                            _Compare, _Alloc>::_Base_ptr,
2219          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2220                            _Compare, _Alloc>::_Base_ptr>
2221     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2222     _M_get_insert_hint_equal_pos(const_iterator __position, const key_type& __k)
2223     {
2224       iterator __pos = __position._M_const_cast();
2225       typedef pair<_Base_ptr, _Base_ptr> _Res;
2226
2227       // end()
2228       if (__pos._M_node == _M_end())
2229         {
2230           if (size() > 0
2231               && !_M_impl._M_key_compare(__k, _S_key(_M_rightmost())))
2232             return _Res(0, _M_rightmost());
2233           else
2234             return _M_get_insert_equal_pos(__k);
2235         }
2236       else if (!_M_impl._M_key_compare(_S_key(__pos._M_node), __k))
2237         {
2238           // First, try before...
2239           iterator __before = __pos;
2240           if (__pos._M_node == _M_leftmost()) // begin()
2241             return _Res(_M_leftmost(), _M_leftmost());
2242           else if (!_M_impl._M_key_compare(__k, _S_key((--__before)._M_node)))
2243             {
2244               if (_S_right(__before._M_node) == 0)
2245                 return _Res(0, __before._M_node);
2246               else
2247                 return _Res(__pos._M_node, __pos._M_node);
2248             }
2249           else
2250             return _M_get_insert_equal_pos(__k);
2251         }
2252       else
2253         {
2254           // ... then try after.
2255           iterator __after = __pos;
2256           if (__pos._M_node == _M_rightmost())
2257             return _Res(0, _M_rightmost());
2258           else if (!_M_impl._M_key_compare(_S_key((++__after)._M_node), __k))
2259             {
2260               if (_S_right(__pos._M_node) == 0)
2261                 return _Res(0, __pos._M_node);
2262               else
2263                 return _Res(__after._M_node, __after._M_node);
2264             }
2265           else
2266             return _Res(0, 0);
2267         }
2268     }
2269
2270   template<typename _Key, typename _Val, typename _KeyOfValue,
2271            typename _Compare, typename _Alloc>
2272 #if __cplusplus >= 201103L
2273     template<typename _Arg, typename _NodeGen>
2274 #else
2275     template<typename _NodeGen>
2276 #endif
2277       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2278       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2279       _M_insert_equal_(const_iterator __position,
2280 #if __cplusplus >= 201103L
2281                        _Arg&& __v,
2282 #else
2283                        const _Val& __v,
2284 #endif
2285                        _NodeGen& __node_gen)
2286       {
2287         pair<_Base_ptr, _Base_ptr> __res
2288           = _M_get_insert_hint_equal_pos(__position, _KeyOfValue()(__v));
2289
2290         if (__res.second)
2291           return _M_insert_(__res.first, __res.second,
2292                             _GLIBCXX_FORWARD(_Arg, __v),
2293                             __node_gen);
2294
2295         return _M_insert_equal_lower(_GLIBCXX_FORWARD(_Arg, __v));
2296       }
2297
2298 #if __cplusplus >= 201103L
2299   template<typename _Key, typename _Val, typename _KeyOfValue,
2300            typename _Compare, typename _Alloc>
2301     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2302     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2303     _M_insert_node(_Base_ptr __x, _Base_ptr __p, _Link_type __z)
2304     {
2305       bool __insert_left = (__x != 0 || __p == _M_end()
2306                             || _M_impl._M_key_compare(_S_key(__z),
2307                                                       _S_key(__p)));
2308
2309       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
2310                                     this->_M_impl._M_header);
2311       ++_M_impl._M_node_count;
2312       return iterator(__z);
2313     }
2314
2315   template<typename _Key, typename _Val, typename _KeyOfValue,
2316            typename _Compare, typename _Alloc>
2317     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2318     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2319     _M_insert_lower_node(_Base_ptr __p, _Link_type __z)
2320     {
2321       bool __insert_left = (__p == _M_end()
2322                             || !_M_impl._M_key_compare(_S_key(__p),
2323                                                        _S_key(__z)));
2324
2325       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
2326                                     this->_M_impl._M_header);
2327       ++_M_impl._M_node_count;
2328       return iterator(__z);
2329     }
2330
2331   template<typename _Key, typename _Val, typename _KeyOfValue,
2332            typename _Compare, typename _Alloc>
2333     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2334     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2335     _M_insert_equal_lower_node(_Link_type __z)
2336     {
2337       _Link_type __x = _M_begin();
2338       _Base_ptr __y = _M_end();
2339       while (__x != 0)
2340         {
2341           __y = __x;
2342           __x = !_M_impl._M_key_compare(_S_key(__x), _S_key(__z)) ?
2343                 _S_left(__x) : _S_right(__x);
2344         }
2345       return _M_insert_lower_node(__y, __z);
2346     }
2347
2348   template<typename _Key, typename _Val, typename _KeyOfValue,
2349            typename _Compare, typename _Alloc>
2350     template<typename... _Args>
2351       pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2352                              _Compare, _Alloc>::iterator, bool>
2353       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2354       _M_emplace_unique(_Args&&... __args)
2355       {
2356         _Link_type __z = _M_create_node(std::forward<_Args>(__args)...);
2357
2358         __try
2359           {
2360             typedef pair<iterator, bool> _Res;
2361             auto __res = _M_get_insert_unique_pos(_S_key(__z));
2362             if (__res.second)
2363               return _Res(_M_insert_node(__res.first, __res.second, __z), true);
2364
2365             _M_drop_node(__z);
2366             return _Res(iterator(__res.first), false);
2367           }
2368         __catch(...)
2369           {
2370             _M_drop_node(__z);
2371             __throw_exception_again;
2372           }
2373       }
2374
2375   template<typename _Key, typename _Val, typename _KeyOfValue,
2376            typename _Compare, typename _Alloc>
2377     template<typename... _Args>
2378       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2379       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2380       _M_emplace_equal(_Args&&... __args)
2381       {
2382         _Link_type __z = _M_create_node(std::forward<_Args>(__args)...);
2383
2384         __try
2385           {
2386             auto __res = _M_get_insert_equal_pos(_S_key(__z));
2387             return _M_insert_node(__res.first, __res.second, __z);
2388           }
2389         __catch(...)
2390           {
2391             _M_drop_node(__z);
2392             __throw_exception_again;
2393           }
2394       }
2395
2396   template<typename _Key, typename _Val, typename _KeyOfValue,
2397            typename _Compare, typename _Alloc>
2398     template<typename... _Args>
2399       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2400       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2401       _M_emplace_hint_unique(const_iterator __pos, _Args&&... __args)
2402       {
2403         _Link_type __z = _M_create_node(std::forward<_Args>(__args)...);
2404
2405         __try
2406           {
2407             auto __res = _M_get_insert_hint_unique_pos(__pos, _S_key(__z));
2408
2409             if (__res.second)
2410               return _M_insert_node(__res.first, __res.second, __z);
2411
2412             _M_drop_node(__z);
2413             return iterator(__res.first);
2414           }
2415         __catch(...)
2416           {
2417             _M_drop_node(__z);
2418             __throw_exception_again;
2419           }
2420       }
2421
2422   template<typename _Key, typename _Val, typename _KeyOfValue,
2423            typename _Compare, typename _Alloc>
2424     template<typename... _Args>
2425       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2426       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2427       _M_emplace_hint_equal(const_iterator __pos, _Args&&... __args)
2428       {
2429         _Link_type __z = _M_create_node(std::forward<_Args>(__args)...);
2430
2431         __try
2432           {
2433             auto __res = _M_get_insert_hint_equal_pos(__pos, _S_key(__z));
2434
2435             if (__res.second)
2436               return _M_insert_node(__res.first, __res.second, __z);
2437
2438             return _M_insert_equal_lower_node(__z);
2439           }
2440         __catch(...)
2441           {
2442             _M_drop_node(__z);
2443             __throw_exception_again;
2444           }
2445       }
2446 #endif
2447
2448   template<typename _Key, typename _Val, typename _KoV,
2449            typename _Cmp, typename _Alloc>
2450     template<class _II>
2451       void
2452       _Rb_tree<_Key, _Val, _KoV, _Cmp, _Alloc>::
2453       _M_insert_unique(_II __first, _II __last)
2454       {
2455         _Alloc_node __an(*this);
2456         for (; __first != __last; ++__first)
2457           _M_insert_unique_(end(), *__first, __an);
2458       }
2459
2460   template<typename _Key, typename _Val, typename _KoV,
2461            typename _Cmp, typename _Alloc>
2462     template<class _II>
2463       void
2464       _Rb_tree<_Key, _Val, _KoV, _Cmp, _Alloc>::
2465       _M_insert_equal(_II __first, _II __last)
2466       {
2467         _Alloc_node __an(*this);
2468         for (; __first != __last; ++__first)
2469           _M_insert_equal_(end(), *__first, __an);
2470       }
2471
2472   template<typename _Key, typename _Val, typename _KeyOfValue,
2473            typename _Compare, typename _Alloc>
2474     void
2475     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2476     _M_erase_aux(const_iterator __position)
2477     {
2478       _Link_type __y =
2479         static_cast<_Link_type>(_Rb_tree_rebalance_for_erase
2480                                 (const_cast<_Base_ptr>(__position._M_node),
2481                                  this->_M_impl._M_header));
2482       _M_drop_node(__y);
2483       --_M_impl._M_node_count;
2484     }
2485
2486   template<typename _Key, typename _Val, typename _KeyOfValue,
2487            typename _Compare, typename _Alloc>
2488     void
2489     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2490     _M_erase_aux(const_iterator __first, const_iterator __last)
2491     {
2492       if (__first == begin() && __last == end())
2493         clear();
2494       else
2495         while (__first != __last)
2496           _M_erase_aux(__first++);
2497     }
2498
2499   template<typename _Key, typename _Val, typename _KeyOfValue,
2500            typename _Compare, typename _Alloc>
2501     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::size_type
2502     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2503     erase(const _Key& __x)
2504     {
2505       pair<iterator, iterator> __p = equal_range(__x);
2506       const size_type __old_size = size();
2507       _M_erase_aux(__p.first, __p.second);
2508       return __old_size - size();
2509     }
2510
2511   template<typename _Key, typename _Val, typename _KeyOfValue,
2512            typename _Compare, typename _Alloc>
2513     void
2514     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2515     erase(const _Key* __first, const _Key* __last)
2516     {
2517       while (__first != __last)
2518         erase(*__first++);
2519     }
2520
2521   template<typename _Key, typename _Val, typename _KeyOfValue,
2522            typename _Compare, typename _Alloc>
2523     typename _Rb_tree<_Key, _Val, _KeyOfValue,
2524                       _Compare, _Alloc>::iterator
2525     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2526     find(const _Key& __k)
2527     {
2528       iterator __j = _M_lower_bound(_M_begin(), _M_end(), __k);
2529       return (__j == end()
2530               || _M_impl._M_key_compare(__k,
2531                                         _S_key(__j._M_node))) ? end() : __j;
2532     }
2533
2534   template<typename _Key, typename _Val, typename _KeyOfValue,
2535            typename _Compare, typename _Alloc>
2536     typename _Rb_tree<_Key, _Val, _KeyOfValue,
2537                       _Compare, _Alloc>::const_iterator
2538     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2539     find(const _Key& __k) const
2540     {
2541       const_iterator __j = _M_lower_bound(_M_begin(), _M_end(), __k);
2542       return (__j == end()
2543               || _M_impl._M_key_compare(__k,
2544                                         _S_key(__j._M_node))) ? end() : __j;
2545     }
2546
2547   template<typename _Key, typename _Val, typename _KeyOfValue,
2548            typename _Compare, typename _Alloc>
2549     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::size_type
2550     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2551     count(const _Key& __k) const
2552     {
2553       pair<const_iterator, const_iterator> __p = equal_range(__k);
2554       const size_type __n = std::distance(__p.first, __p.second);
2555       return __n;
2556     }
2557
2558   _GLIBCXX_PURE unsigned int
2559   _Rb_tree_black_count(const _Rb_tree_node_base* __node,
2560                        const _Rb_tree_node_base* __root) throw ();
2561
2562   template<typename _Key, typename _Val, typename _KeyOfValue,
2563            typename _Compare, typename _Alloc>
2564     bool
2565     _Rb_tree<_Key,_Val,_KeyOfValue,_Compare,_Alloc>::__rb_verify() const
2566     {
2567       if (_M_impl._M_node_count == 0 || begin() == end())
2568         return _M_impl._M_node_count == 0 && begin() == end()
2569                && this->_M_impl._M_header._M_left == _M_end()
2570                && this->_M_impl._M_header._M_right == _M_end();
2571
2572       unsigned int __len = _Rb_tree_black_count(_M_leftmost(), _M_root());
2573       for (const_iterator __it = begin(); __it != end(); ++__it)
2574         {
2575           _Const_Link_type __x = static_cast<_Const_Link_type>(__it._M_node);
2576           _Const_Link_type __L = _S_left(__x);
2577           _Const_Link_type __R = _S_right(__x);
2578
2579           if (__x->_M_color == _S_red)
2580             if ((__L && __L->_M_color == _S_red)
2581                 || (__R && __R->_M_color == _S_red))
2582               return false;
2583
2584           if (__L && _M_impl._M_key_compare(_S_key(__x), _S_key(__L)))
2585             return false;
2586           if (__R && _M_impl._M_key_compare(_S_key(__R), _S_key(__x)))
2587             return false;
2588
2589           if (!__L && !__R && _Rb_tree_black_count(__x, _M_root()) != __len)
2590             return false;
2591         }
2592
2593       if (_M_leftmost() != _Rb_tree_node_base::_S_minimum(_M_root()))
2594         return false;
2595       if (_M_rightmost() != _Rb_tree_node_base::_S_maximum(_M_root()))
2596         return false;
2597       return true;
2598     }
2599
2600 #if __cplusplus > 201402L
2601   // Allow access to internals of compatible _Rb_tree specializations.
2602   template<typename _Key, typename _Val, typename _Sel, typename _Cmp1,
2603            typename _Alloc, typename _Cmp2>
2604     struct _Rb_tree_merge_helper<_Rb_tree<_Key, _Val, _Sel, _Cmp1, _Alloc>,
2605                                  _Cmp2>
2606     {
2607     private:
2608       friend class _Rb_tree<_Key, _Val, _Sel, _Cmp1, _Alloc>;
2609
2610       static auto&
2611       _S_get_impl(_Rb_tree<_Key, _Val, _Sel, _Cmp2, _Alloc>& __tree)
2612       { return __tree._M_impl; }
2613     };
2614 #endif // C++17
2615
2616 _GLIBCXX_END_NAMESPACE_VERSION
2617 } // namespace
2618
2619 #endif