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

   1 // RB tree implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001-2024 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   // Red-black tree class, designed for use in implementing STL
  80   // associative containers (set, multiset, map, and multimap). The
  81   // insertion and deletion algorithms are based on those in Cormen,
  82   // Leiserson, and Rivest, Introduction to Algorithms (MIT Press,
  83   // 1990), except that
  84   //
  85   // (1) the header cell is maintained with links not only to the root
  86   // but also to the leftmost node of the tree, to enable constant
  87   // time begin(), and to the rightmost node of the tree, to enable
  88   // linear time performance when used with the generic set algorithms
  89   // (set_union, etc.)
  90   //
  91   // (2) when a node being deleted has two children its successor node
  92   // is relinked into its place, rather than copied, so that the only
  93   // iterators invalidated are those referring to the deleted node.
  94
  95   enum _Rb_tree_color { _S_red = false, _S_black = true };
  96
  97   struct _Rb_tree_node_base
  98   {
  99     typedef _Rb_tree_node_base* _Base_ptr;
 100     typedef const _Rb_tree_node_base* _Const_Base_ptr;
 101
 102     _Rb_tree_color      _M_color;
 103     _Base_ptr           _M_parent;
 104     _Base_ptr           _M_left;
 105     _Base_ptr           _M_right;
 106
 107     static _Base_ptr
 108     _S_minimum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 109     {
 110       while (__x->_M_left != 0) __x = __x->_M_left;
 111       return __x;
 112     }
 113
 114     static _Const_Base_ptr
 115     _S_minimum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 116     {
 117       while (__x->_M_left != 0) __x = __x->_M_left;
 118       return __x;
 119     }
 120
 121     static _Base_ptr
 122     _S_maximum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 123     {
 124       while (__x->_M_right != 0) __x = __x->_M_right;
 125       return __x;
 126     }
 127
 128     static _Const_Base_ptr
 129     _S_maximum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 130     {
 131       while (__x->_M_right != 0) __x = __x->_M_right;
 132       return __x;
 133     }
 134   };
 135
 136   // Helper type offering value initialization guarantee on the compare functor.
 137   template<typename _Key_compare>
 138     struct _Rb_tree_key_compare
 139     {
 140       _Key_compare              _M_key_compare;
 141
 142       _Rb_tree_key_compare()
 143       _GLIBCXX_NOEXCEPT_IF(
 144         is_nothrow_default_constructible<_Key_compare>::value)
 145       : _M_key_compare()
 146       { }
 147
 148       _Rb_tree_key_compare(const _Key_compare& __comp)
 149       : _M_key_compare(__comp)
 150       { }
 151
 152 #if __cplusplus >= 201103L
 153       // Copy constructor added for consistency with C++98 mode.
 154       _Rb_tree_key_compare(const _Rb_tree_key_compare&) = default;
 155
 156       _Rb_tree_key_compare(_Rb_tree_key_compare&& __x)
 157         noexcept(is_nothrow_copy_constructible<_Key_compare>::value)
 158       : _M_key_compare(__x._M_key_compare)
 159       { }
 160 #endif
 161     };
 162
 163   // Helper type to manage default initialization of node count and header.
 164   struct _Rb_tree_header
 165   {
 166     _Rb_tree_node_base  _M_header;
 167     size_t              _M_node_count; // Keeps track of size of tree.
 168
 169     _Rb_tree_header() _GLIBCXX_NOEXCEPT
 170     {
 171       _M_header._M_color = _S_red;
 172       _M_reset();
 173     }
 174
 175 #if __cplusplus >= 201103L
 176     _Rb_tree_header(_Rb_tree_header&& __x) noexcept
 177     {
 178       if (__x._M_header._M_parent != nullptr)
 179         _M_move_data(__x);
 180       else
 181         {
 182           _M_header._M_color = _S_red;
 183           _M_reset();
 184         }
 185     }
 186 #endif
 187
 188     void
 189     _M_move_data(_Rb_tree_header& __from)
 190     {
 191       _M_header._M_color = __from._M_header._M_color;
 192       _M_header._M_parent = __from._M_header._M_parent;
 193       _M_header._M_left = __from._M_header._M_left;
 194       _M_header._M_right = __from._M_header._M_right;
 195       _M_header._M_parent->_M_parent = &_M_header;
 196       _M_node_count = __from._M_node_count;
 197
 198       __from._M_reset();
 199     }
 200
 201     void
 202     _M_reset()
 203     {
 204       _M_header._M_parent = 0;
 205       _M_header._M_left = &_M_header;
 206       _M_header._M_right = &_M_header;
 207       _M_node_count = 0;
 208     }
 209   };
 210
 211   template<typename _Val>
 212     struct _Rb_tree_node : public _Rb_tree_node_base
 213     {
 214       typedef _Rb_tree_node<_Val>* _Link_type;
 215
 216 #if __cplusplus < 201103L
 217       _Val _M_value_field;
 218
 219       _Val*
 220       _M_valptr()
 221       { return std::__addressof(_M_value_field); }
 222
 223       const _Val*
 224       _M_valptr() const
 225       { return std::__addressof(_M_value_field); }
 226 #else
 227       __gnu_cxx::__aligned_membuf<_Val> _M_storage;
 228
 229       _Val*
 230       _M_valptr()
 231       { return _M_storage._M_ptr(); }
 232
 233       const _Val*
 234       _M_valptr() const
 235       { return _M_storage._M_ptr(); }
 236 #endif
 237     };
 238
 239   _GLIBCXX_PURE _Rb_tree_node_base*
 240   _Rb_tree_increment(_Rb_tree_node_base* __x) throw ();
 241
 242   _GLIBCXX_PURE const _Rb_tree_node_base*
 243   _Rb_tree_increment(const _Rb_tree_node_base* __x) throw ();
 244
 245   _GLIBCXX_PURE _Rb_tree_node_base*
 246   _Rb_tree_decrement(_Rb_tree_node_base* __x) throw ();
 247
 248   _GLIBCXX_PURE const _Rb_tree_node_base*
 249   _Rb_tree_decrement(const _Rb_tree_node_base* __x) throw ();
 250
 251   template<typename _Tp>
 252     struct _Rb_tree_iterator
 253     {
 254       typedef _Tp  value_type;
 255       typedef _Tp& reference;
 256       typedef _Tp* pointer;
 257
 258       typedef bidirectional_iterator_tag iterator_category;
 259       typedef ptrdiff_t                  difference_type;
 260
 261       typedef _Rb_tree_iterator<_Tp>            _Self;
 262       typedef _Rb_tree_node_base::_Base_ptr     _Base_ptr;
 263       typedef _Rb_tree_node<_Tp>*               _Link_type;
 264
 265       _Rb_tree_iterator() _GLIBCXX_NOEXCEPT
 266       : _M_node() { }
 267
 268       explicit
 269       _Rb_tree_iterator(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 270       : _M_node(__x) { }
 271
 272       reference
 273       operator*() const _GLIBCXX_NOEXCEPT
 274       { return *static_cast<_Link_type>(_M_node)->_M_valptr(); }
 275
 276       pointer
 277       operator->() const _GLIBCXX_NOEXCEPT
 278       { return static_cast<_Link_type> (_M_node)->_M_valptr(); }
 279
 280       _Self&
 281       operator++() _GLIBCXX_NOEXCEPT
 282       {
 283         _M_node = _Rb_tree_increment(_M_node);
 284         return *this;
 285       }
 286
 287       _Self
 288       operator++(int) _GLIBCXX_NOEXCEPT
 289       {
 290         _Self __tmp = *this;
 291         _M_node = _Rb_tree_increment(_M_node);
 292         return __tmp;
 293       }
 294
 295       _Self&
 296       operator--() _GLIBCXX_NOEXCEPT
 297       {
 298         _M_node = _Rb_tree_decrement(_M_node);
 299         return *this;
 300       }
 301
 302       _Self
 303       operator--(int) _GLIBCXX_NOEXCEPT
 304       {
 305         _Self __tmp = *this;
 306         _M_node = _Rb_tree_decrement(_M_node);
 307         return __tmp;
 308       }
 309
 310       friend bool
 311       operator==(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
 312       { return __x._M_node == __y._M_node; }
 313
 314 #if ! __cpp_lib_three_way_comparison
 315       friend bool
 316       operator!=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
 317       { return __x._M_node != __y._M_node; }
 318 #endif
 319
 320       _Base_ptr _M_node;
 321     };
 322
 323   template<typename _Tp>
 324     struct _Rb_tree_const_iterator
 325     {
 326       typedef _Tp        value_type;
 327       typedef const _Tp& reference;
 328       typedef const _Tp* pointer;
 329
 330       typedef _Rb_tree_iterator<_Tp> iterator;
 331
 332       typedef bidirectional_iterator_tag iterator_category;
 333       typedef ptrdiff_t                  difference_type;
 334
 335       typedef _Rb_tree_const_iterator<_Tp>              _Self;
 336       typedef _Rb_tree_node_base::_Const_Base_ptr       _Base_ptr;
 337       typedef const _Rb_tree_node<_Tp>*                 _Link_type;
 338
 339       _Rb_tree_const_iterator() _GLIBCXX_NOEXCEPT
 340       : _M_node() { }
 341
 342       explicit
 343       _Rb_tree_const_iterator(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 344       : _M_node(__x) { }
 345
 346       _Rb_tree_const_iterator(const iterator& __it) _GLIBCXX_NOEXCEPT
 347       : _M_node(__it._M_node) { }
 348
 349       iterator
 350       _M_const_cast() const _GLIBCXX_NOEXCEPT
 351       { return iterator(const_cast<typename iterator::_Base_ptr>(_M_node)); }
 352
 353       reference
 354       operator*() const _GLIBCXX_NOEXCEPT
 355       { return *static_cast<_Link_type>(_M_node)->_M_valptr(); }
 356
 357       pointer
 358       operator->() const _GLIBCXX_NOEXCEPT
 359       { return static_cast<_Link_type>(_M_node)->_M_valptr(); }
 360
 361       _Self&
 362       operator++() _GLIBCXX_NOEXCEPT
 363       {
 364         _M_node = _Rb_tree_increment(_M_node);
 365         return *this;
 366       }
 367
 368       _Self
 369       operator++(int) _GLIBCXX_NOEXCEPT
 370       {
 371         _Self __tmp = *this;
 372         _M_node = _Rb_tree_increment(_M_node);
 373         return __tmp;
 374       }
 375
 376       _Self&
 377       operator--() _GLIBCXX_NOEXCEPT
 378       {
 379         _M_node = _Rb_tree_decrement(_M_node);
 380         return *this;
 381       }
 382
 383       _Self
 384       operator--(int) _GLIBCXX_NOEXCEPT
 385       {
 386         _Self __tmp = *this;
 387         _M_node = _Rb_tree_decrement(_M_node);
 388         return __tmp;
 389       }
 390
 391       friend bool
 392       operator==(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
 393       { return __x._M_node == __y._M_node; }
 394
 395 #if ! __cpp_lib_three_way_comparison
 396       friend bool
 397       operator!=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
 398       { return __x._M_node != __y._M_node; }
 399 #endif
 400
 401       _Base_ptr _M_node;
 402     };
 403
 404   __attribute__((__nonnull__))
 405   void
 406   _Rb_tree_insert_and_rebalance(const bool __insert_left,
 407                                 _Rb_tree_node_base* __x,
 408                                 _Rb_tree_node_base* __p,
 409                                 _Rb_tree_node_base& __header) throw ();
 410
 411   __attribute__((__nonnull__,__returns_nonnull__))
 412   _Rb_tree_node_base*
 413   _Rb_tree_rebalance_for_erase(_Rb_tree_node_base* const __z,
 414                                _Rb_tree_node_base& __header) throw ();
 415
 416 #if __cplusplus > 201402L
 417   template<typename _Tree1, typename _Cmp2>
 418     struct _Rb_tree_merge_helper { };
 419 #endif
 420
 421   template<typename _Key, typename _Val, typename _KeyOfValue,
 422            typename _Compare, typename _Alloc = allocator<_Val> >
 423     class _Rb_tree
 424     {
 425       typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
 426         rebind<_Rb_tree_node<_Val> >::other _Node_allocator;
 427
 428       typedef __gnu_cxx::__alloc_traits<_Node_allocator> _Alloc_traits;
 429
 430     protected:
 431       typedef _Rb_tree_node_base*               _Base_ptr;
 432       typedef const _Rb_tree_node_base*         _Const_Base_ptr;
 433       typedef _Rb_tree_node<_Val>*              _Link_type;
 434       typedef const _Rb_tree_node<_Val>*        _Const_Link_type;
 435
 436     private:
 437       // Functor recycling a pool of nodes and using allocation once the pool
 438       // is empty.
 439       struct _Reuse_or_alloc_node
 440       {
 441         _Reuse_or_alloc_node(_Rb_tree& __t)
 442         : _M_root(__t._M_root()), _M_nodes(__t._M_rightmost()), _M_t(__t)
 443         {
 444           if (_M_root)
 445             {
 446               _M_root->_M_parent = 0;
 447
 448               if (_M_nodes->_M_left)
 449                 _M_nodes = _M_nodes->_M_left;
 450             }
 451           else
 452             _M_nodes = 0;
 453         }
 454
 455 #if __cplusplus >= 201103L
 456         _Reuse_or_alloc_node(const _Reuse_or_alloc_node&) = delete;
 457 #endif
 458
 459         ~_Reuse_or_alloc_node()
 460         { _M_t._M_erase(static_cast<_Link_type>(_M_root)); }
 461
 462         template<typename _Arg>
 463           _Link_type
 464           operator()(_GLIBCXX_FWDREF(_Arg) __arg)
 465           {
 466             _Link_type __node = static_cast<_Link_type>(_M_extract());
 467             if (__node)
 468               {
 469                 _M_t._M_destroy_node(__node);
 470                 _M_t._M_construct_node(__node, _GLIBCXX_FORWARD(_Arg, __arg));
 471                 return __node;
 472               }
 473
 474             return _M_t._M_create_node(_GLIBCXX_FORWARD(_Arg, __arg));
 475           }
 476
 477       private:
 478         _Base_ptr
 479         _M_extract()
 480         {
 481           if (!_M_nodes)
 482             return _M_nodes;
 483
 484           _Base_ptr __node = _M_nodes;
 485           _M_nodes = _M_nodes->_M_parent;
 486           if (_M_nodes)
 487             {
 488               if (_M_nodes->_M_right == __node)
 489                 {
 490                   _M_nodes->_M_right = 0;
 491
 492                   if (_M_nodes->_M_left)
 493                     {
 494                       _M_nodes = _M_nodes->_M_left;
 495
 496                       while (_M_nodes->_M_right)
 497                         _M_nodes = _M_nodes->_M_right;
 498
 499                       if (_M_nodes->_M_left)
 500                         _M_nodes = _M_nodes->_M_left;
 501                     }
 502                 }
 503               else // __node is on the left.
 504                 _M_nodes->_M_left = 0;
 505             }
 506           else
 507             _M_root = 0;
 508
 509           return __node;
 510         }
 511
 512         _Base_ptr _M_root;
 513         _Base_ptr _M_nodes;
 514         _Rb_tree& _M_t;
 515       };
 516
 517       // Functor similar to the previous one but without any pool of nodes to
 518       // recycle.
 519       struct _Alloc_node
 520       {
 521         _Alloc_node(_Rb_tree& __t)
 522         : _M_t(__t) { }
 523
 524         template<typename _Arg>
 525           _Link_type
 526           operator()(_GLIBCXX_FWDREF(_Arg) __arg) const
 527           { return _M_t._M_create_node(_GLIBCXX_FORWARD(_Arg, __arg)); }
 528
 529       private:
 530         _Rb_tree& _M_t;
 531       };
 532
 533     public:
 534       typedef _Key                              key_type;
 535       typedef _Val                              value_type;
 536       typedef value_type*                       pointer;
 537       typedef const value_type*                 const_pointer;
 538       typedef value_type&                       reference;
 539       typedef const value_type&                 const_reference;
 540       typedef size_t                            size_type;
 541       typedef ptrdiff_t                         difference_type;
 542       typedef _Alloc                            allocator_type;
 543
 544       _Node_allocator&
 545       _M_get_Node_allocator() _GLIBCXX_NOEXCEPT
 546       { return this->_M_impl; }
 547
 548       const _Node_allocator&
 549       _M_get_Node_allocator() const _GLIBCXX_NOEXCEPT
 550       { return this->_M_impl; }
 551
 552       allocator_type
 553       get_allocator() const _GLIBCXX_NOEXCEPT
 554       { return allocator_type(_M_get_Node_allocator()); }
 555
 556     protected:
 557       _Link_type
 558       _M_get_node()
 559       { return _Alloc_traits::allocate(_M_get_Node_allocator(), 1); }
 560
 561       void
 562       _M_put_node(_Link_type __p) _GLIBCXX_NOEXCEPT
 563       { _Alloc_traits::deallocate(_M_get_Node_allocator(), __p, 1); }
 564
 565 #if __cplusplus < 201103L
 566       void
 567       _M_construct_node(_Link_type __node, const value_type& __x)
 568       {
 569         __try
 570           { get_allocator().construct(__node->_M_valptr(), __x); }
 571         __catch(...)
 572           {
 573             _M_put_node(__node);
 574             __throw_exception_again;
 575           }
 576       }
 577
 578       _Link_type
 579       _M_create_node(const value_type& __x)
 580       {
 581         _Link_type __tmp = _M_get_node();
 582         _M_construct_node(__tmp, __x);
 583         return __tmp;
 584       }
 585 #else
 586       template<typename... _Args>
 587         void
 588         _M_construct_node(_Link_type __node, _Args&&... __args)
 589         {
 590           __try
 591             {
 592               ::new(__node) _Rb_tree_node<_Val>;
 593               _Alloc_traits::construct(_M_get_Node_allocator(),
 594                                        __node->_M_valptr(),
 595                                        std::forward<_Args>(__args)...);
 596             }
 597           __catch(...)
 598             {
 599               __node->~_Rb_tree_node<_Val>();
 600               _M_put_node(__node);
 601               __throw_exception_again;
 602             }
 603         }
 604
 605       template<typename... _Args>
 606         _Link_type
 607         _M_create_node(_Args&&... __args)
 608         {
 609           _Link_type __tmp = _M_get_node();
 610           _M_construct_node(__tmp, std::forward<_Args>(__args)...);
 611           return __tmp;
 612         }
 613 #endif
 614
 615       void
 616       _M_destroy_node(_Link_type __p) _GLIBCXX_NOEXCEPT
 617       {
 618 #if __cplusplus < 201103L
 619         get_allocator().destroy(__p->_M_valptr());
 620 #else
 621         _Alloc_traits::destroy(_M_get_Node_allocator(), __p->_M_valptr());
 622         __p->~_Rb_tree_node<_Val>();
 623 #endif
 624       }
 625
 626       void
 627       _M_drop_node(_Link_type __p) _GLIBCXX_NOEXCEPT
 628       {
 629         _M_destroy_node(__p);
 630         _M_put_node(__p);
 631       }
 632
 633       template<bool _MoveValue, typename _NodeGen>
 634         _Link_type
 635         _M_clone_node(_Link_type __x, _NodeGen& __node_gen)
 636         {
 637 #if __cplusplus >= 201103L
 638           using _Vp = __conditional_t<_MoveValue,
 639                                       value_type&&,
 640                                       const value_type&>;
 641 #endif
 642           _Link_type __tmp
 643             = __node_gen(_GLIBCXX_FORWARD(_Vp, *__x->_M_valptr()));
 644           __tmp->_M_color = __x->_M_color;
 645           __tmp->_M_left = 0;
 646           __tmp->_M_right = 0;
 647           return __tmp;
 648         }
 649
 650     protected:
 651 #if _GLIBCXX_INLINE_VERSION
 652       template<typename _Key_compare>
 653 #else
 654       // Unused _Is_pod_comparator is kept as it is part of mangled name.
 655       template<typename _Key_compare,
 656                bool /* _Is_pod_comparator */ = __is_pod(_Key_compare)>
 657 #endif
 658         struct _Rb_tree_impl
 659         : public _Node_allocator
 660         , public _Rb_tree_key_compare<_Key_compare>
 661         , public _Rb_tree_header
 662         {
 663           typedef _Rb_tree_key_compare<_Key_compare> _Base_key_compare;
 664
 665           _Rb_tree_impl()
 666             _GLIBCXX_NOEXCEPT_IF(
 667                 is_nothrow_default_constructible<_Node_allocator>::value
 668                 && is_nothrow_default_constructible<_Base_key_compare>::value )
 669           : _Node_allocator()
 670           { }
 671
 672           _Rb_tree_impl(const _Rb_tree_impl& __x)
 673           : _Node_allocator(_Alloc_traits::_S_select_on_copy(__x))
 674           , _Base_key_compare(__x._M_key_compare)
 675           , _Rb_tree_header()
 676           { }
 677
 678 #if __cplusplus < 201103L
 679           _Rb_tree_impl(const _Key_compare& __comp, const _Node_allocator& __a)
 680           : _Node_allocator(__a), _Base_key_compare(__comp)
 681           { }
 682 #else
 683           _Rb_tree_impl(_Rb_tree_impl&&)
 684             noexcept( is_nothrow_move_constructible<_Base_key_compare>::value )
 685           = default;
 686
 687           explicit
 688           _Rb_tree_impl(_Node_allocator&& __a)
 689           : _Node_allocator(std::move(__a))
 690           { }
 691
 692           _Rb_tree_impl(_Rb_tree_impl&& __x, _Node_allocator&& __a)
 693           : _Node_allocator(std::move(__a)),
 694             _Base_key_compare(std::move(__x)),
 695             _Rb_tree_header(std::move(__x))
 696           { }
 697
 698           _Rb_tree_impl(const _Key_compare& __comp, _Node_allocator&& __a)
 699           : _Node_allocator(std::move(__a)), _Base_key_compare(__comp)
 700           { }
 701 #endif
 702         };
 703
 704       _Rb_tree_impl<_Compare> _M_impl;
 705
 706     protected:
 707       _Base_ptr&
 708       _M_root() _GLIBCXX_NOEXCEPT
 709       { return this->_M_impl._M_header._M_parent; }
 710
 711       _Const_Base_ptr
 712       _M_root() const _GLIBCXX_NOEXCEPT
 713       { return this->_M_impl._M_header._M_parent; }
 714
 715       _Base_ptr&
 716       _M_leftmost() _GLIBCXX_NOEXCEPT
 717       { return this->_M_impl._M_header._M_left; }
 718
 719       _Const_Base_ptr
 720       _M_leftmost() const _GLIBCXX_NOEXCEPT
 721       { return this->_M_impl._M_header._M_left; }
 722
 723       _Base_ptr&
 724       _M_rightmost() _GLIBCXX_NOEXCEPT
 725       { return this->_M_impl._M_header._M_right; }
 726
 727       _Const_Base_ptr
 728       _M_rightmost() const _GLIBCXX_NOEXCEPT
 729       { return this->_M_impl._M_header._M_right; }
 730
 731       _Link_type
 732       _M_mbegin() const _GLIBCXX_NOEXCEPT
 733       { return static_cast<_Link_type>(this->_M_impl._M_header._M_parent); }
 734
 735       _Link_type
 736       _M_begin() _GLIBCXX_NOEXCEPT
 737       { return _M_mbegin(); }
 738
 739       _Const_Link_type
 740       _M_begin() const _GLIBCXX_NOEXCEPT
 741       {
 742         return static_cast<_Const_Link_type>
 743           (this->_M_impl._M_header._M_parent);
 744       }
 745
 746       _Base_ptr
 747       _M_end() _GLIBCXX_NOEXCEPT
 748       { return &this->_M_impl._M_header; }
 749
 750       _Const_Base_ptr
 751       _M_end() const _GLIBCXX_NOEXCEPT
 752       { return &this->_M_impl._M_header; }
 753
 754       static const _Key&
 755       _S_key(_Const_Link_type __x)
 756       {
 757 #if __cplusplus >= 201103L
 758         // If we're asking for the key we're presumably using the comparison
 759         // object, and so this is a good place to sanity check it.
 760         static_assert(__is_invocable<_Compare&, const _Key&, const _Key&>{},
 761                       "comparison object must be invocable "
 762                       "with two arguments of key type");
 763 # if __cplusplus >= 201703L
 764         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 765         // 2542. Missing const requirements for associative containers
 766         if constexpr (__is_invocable<_Compare&, const _Key&, const _Key&>{})
 767           static_assert(
 768               is_invocable_v<const _Compare&, const _Key&, const _Key&>,
 769               "comparison object must be invocable as const");
 770 # endif // C++17
 771 #endif // C++11
 772
 773         return _KeyOfValue()(*__x->_M_valptr());
 774       }
 775
 776       static _Link_type
 777       _S_left(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 778       { return static_cast<_Link_type>(__x->_M_left); }
 779
 780       static _Const_Link_type
 781       _S_left(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 782       { return static_cast<_Const_Link_type>(__x->_M_left); }
 783
 784       static _Link_type
 785       _S_right(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 786       { return static_cast<_Link_type>(__x->_M_right); }
 787
 788       static _Const_Link_type
 789       _S_right(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 790       { return static_cast<_Const_Link_type>(__x->_M_right); }
 791
 792       static const _Key&
 793       _S_key(_Const_Base_ptr __x)
 794       { return _S_key(static_cast<_Const_Link_type>(__x)); }
 795
 796       static _Base_ptr
 797       _S_minimum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 798       { return _Rb_tree_node_base::_S_minimum(__x); }
 799
 800       static _Const_Base_ptr
 801       _S_minimum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 802       { return _Rb_tree_node_base::_S_minimum(__x); }
 803
 804       static _Base_ptr
 805       _S_maximum(_Base_ptr __x) _GLIBCXX_NOEXCEPT
 806       { return _Rb_tree_node_base::_S_maximum(__x); }
 807
 808       static _Const_Base_ptr
 809       _S_maximum(_Const_Base_ptr __x) _GLIBCXX_NOEXCEPT
 810       { return _Rb_tree_node_base::_S_maximum(__x); }
 811
 812     public:
 813       typedef _Rb_tree_iterator<value_type>       iterator;
 814       typedef _Rb_tree_const_iterator<value_type> const_iterator;
 815
 816       typedef std::reverse_iterator<iterator>       reverse_iterator;
 817       typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
 818
 819 #if __cplusplus > 201402L
 820       using node_type = _Node_handle<_Key, _Val, _Node_allocator>;
 821       using insert_return_type = _Node_insert_return<
 822         __conditional_t<is_same_v<_Key, _Val>, const_iterator, iterator>,
 823         node_type>;
 824 #endif
 825
 826       pair<_Base_ptr, _Base_ptr>
 827       _M_get_insert_unique_pos(const key_type& __k);
 828
 829       pair<_Base_ptr, _Base_ptr>
 830       _M_get_insert_equal_pos(const key_type& __k);
 831
 832       pair<_Base_ptr, _Base_ptr>
 833       _M_get_insert_hint_unique_pos(const_iterator __pos,
 834                                     const key_type& __k);
 835
 836       pair<_Base_ptr, _Base_ptr>
 837       _M_get_insert_hint_equal_pos(const_iterator __pos,
 838                                    const key_type& __k);
 839
 840     private:
 841 #if __cplusplus >= 201103L
 842       template<typename _Arg, typename _NodeGen>
 843         iterator
 844         _M_insert_(_Base_ptr __x, _Base_ptr __y, _Arg&& __v, _NodeGen&);
 845
 846       iterator
 847       _M_insert_node(_Base_ptr __x, _Base_ptr __y, _Link_type __z);
 848
 849       template<typename _Arg>
 850         iterator
 851         _M_insert_lower(_Base_ptr __y, _Arg&& __v);
 852
 853       template<typename _Arg>
 854         iterator
 855         _M_insert_equal_lower(_Arg&& __x);
 856
 857       iterator
 858       _M_insert_lower_node(_Base_ptr __p, _Link_type __z);
 859
 860       iterator
 861       _M_insert_equal_lower_node(_Link_type __z);
 862 #else
 863       template<typename _NodeGen>
 864         iterator
 865         _M_insert_(_Base_ptr __x, _Base_ptr __y,
 866                    const value_type& __v, _NodeGen&);
 867
 868       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 869       // 233. Insertion hints in associative containers.
 870       iterator
 871       _M_insert_lower(_Base_ptr __y, const value_type& __v);
 872
 873       iterator
 874       _M_insert_equal_lower(const value_type& __x);
 875 #endif
 876
 877       enum { __as_lvalue, __as_rvalue };
 878
 879       template<bool _MoveValues, typename _NodeGen>
 880         _Link_type
 881         _M_copy(_Link_type, _Base_ptr, _NodeGen&);
 882
 883       template<bool _MoveValues, typename _NodeGen>
 884         _Link_type
 885         _M_copy(const _Rb_tree& __x, _NodeGen& __gen)
 886         {
 887           _Link_type __root =
 888             _M_copy<_MoveValues>(__x._M_mbegin(), _M_end(), __gen);
 889           _M_leftmost() = _S_minimum(__root);
 890           _M_rightmost() = _S_maximum(__root);
 891           _M_impl._M_node_count = __x._M_impl._M_node_count;
 892           return __root;
 893         }
 894
 895       _Link_type
 896       _M_copy(const _Rb_tree& __x)
 897       {
 898         _Alloc_node __an(*this);
 899         return _M_copy<__as_lvalue>(__x, __an);
 900       }
 901
 902       void
 903       _M_erase(_Link_type __x);
 904
 905       iterator
 906       _M_lower_bound(_Link_type __x, _Base_ptr __y,
 907                      const _Key& __k);
 908
 909       const_iterator
 910       _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 911                      const _Key& __k) const;
 912
 913       iterator
 914       _M_upper_bound(_Link_type __x, _Base_ptr __y,
 915                      const _Key& __k);
 916
 917       const_iterator
 918       _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
 919                      const _Key& __k) const;
 920
 921     public:
 922       // allocation/deallocation
 923 #if __cplusplus < 201103L
 924       _Rb_tree() { }
 925 #else
 926       _Rb_tree() = default;
 927 #endif
 928
 929       _Rb_tree(const _Compare& __comp,
 930                const allocator_type& __a = allocator_type())
 931       : _M_impl(__comp, _Node_allocator(__a)) { }
 932
 933       _Rb_tree(const _Rb_tree& __x)
 934       : _M_impl(__x._M_impl)
 935       {
 936         if (__x._M_root() != 0)
 937           _M_root() = _M_copy(__x);
 938       }
 939
 940 #if __cplusplus >= 201103L
 941       _Rb_tree(const allocator_type& __a)
 942       : _M_impl(_Node_allocator(__a))
 943       { }
 944
 945       _Rb_tree(const _Rb_tree& __x, const allocator_type& __a)
 946       : _M_impl(__x._M_impl._M_key_compare, _Node_allocator(__a))
 947       {
 948         if (__x._M_root() != nullptr)
 949           _M_root() = _M_copy(__x);
 950       }
 951
 952       _Rb_tree(_Rb_tree&&) = default;
 953
 954       _Rb_tree(_Rb_tree&& __x, const allocator_type& __a)
 955       : _Rb_tree(std::move(__x), _Node_allocator(__a))
 956       { }
 957
 958     private:
 959       _Rb_tree(_Rb_tree&& __x, _Node_allocator&& __a, true_type)
 960       noexcept(is_nothrow_default_constructible<_Compare>::value)
 961       : _M_impl(std::move(__x._M_impl), std::move(__a))
 962       { }
 963
 964       _Rb_tree(_Rb_tree&& __x, _Node_allocator&& __a, false_type)
 965       : _M_impl(__x._M_impl._M_key_compare, std::move(__a))
 966       {
 967         if (__x._M_root() != nullptr)
 968           _M_move_data(__x, false_type{});
 969       }
 970
 971     public:
 972       _Rb_tree(_Rb_tree&& __x, _Node_allocator&& __a)
 973       noexcept( noexcept(
 974         _Rb_tree(std::declval<_Rb_tree&&>(), std::declval<_Node_allocator&&>(),
 975                  std::declval<typename _Alloc_traits::is_always_equal>())) )
 976       : _Rb_tree(std::move(__x), std::move(__a),
 977                  typename _Alloc_traits::is_always_equal{})
 978       { }
 979 #endif
 980
 981       ~_Rb_tree() _GLIBCXX_NOEXCEPT
 982       { _M_erase(_M_begin()); }
 983
 984       _Rb_tree&
 985       operator=(const _Rb_tree& __x);
 986
 987       // Accessors.
 988       _Compare
 989       key_comp() const
 990       { return _M_impl._M_key_compare; }
 991
 992       iterator
 993       begin() _GLIBCXX_NOEXCEPT
 994       { return iterator(this->_M_impl._M_header._M_left); }
 995
 996       const_iterator
 997       begin() const _GLIBCXX_NOEXCEPT
 998       { return const_iterator(this->_M_impl._M_header._M_left); }
 999
1000       iterator
1001       end() _GLIBCXX_NOEXCEPT
1002       { return iterator(&this->_M_impl._M_header); }
1003
1004       const_iterator
1005       end() const _GLIBCXX_NOEXCEPT
1006       { return const_iterator(&this->_M_impl._M_header); }
1007
1008       reverse_iterator
1009       rbegin() _GLIBCXX_NOEXCEPT
1010       { return reverse_iterator(end()); }
1011
1012       const_reverse_iterator
1013       rbegin() const _GLIBCXX_NOEXCEPT
1014       { return const_reverse_iterator(end()); }
1015
1016       reverse_iterator
1017       rend() _GLIBCXX_NOEXCEPT
1018       { return reverse_iterator(begin()); }
1019
1020       const_reverse_iterator
1021       rend() const _GLIBCXX_NOEXCEPT
1022       { return const_reverse_iterator(begin()); }
1023
1024       _GLIBCXX_NODISCARD bool
1025       empty() const _GLIBCXX_NOEXCEPT
1026       { return _M_impl._M_node_count == 0; }
1027
1028       size_type
1029       size() const _GLIBCXX_NOEXCEPT
1030       { return _M_impl._M_node_count; }
1031
1032       size_type
1033       max_size() const _GLIBCXX_NOEXCEPT
1034       { return _Alloc_traits::max_size(_M_get_Node_allocator()); }
1035
1036       void
1037       swap(_Rb_tree& __t)
1038       _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value);
1039
1040       // Insert/erase.
1041 #if __cplusplus >= 201103L
1042       template<typename _Arg>
1043         pair<iterator, bool>
1044         _M_insert_unique(_Arg&& __x);
1045
1046       template<typename _Arg>
1047         iterator
1048         _M_insert_equal(_Arg&& __x);
1049
1050       template<typename _Arg, typename _NodeGen>
1051         iterator
1052         _M_insert_unique_(const_iterator __pos, _Arg&& __x, _NodeGen&);
1053
1054       template<typename _Arg>
1055         iterator
1056         _M_insert_unique_(const_iterator __pos, _Arg&& __x)
1057         {
1058           _Alloc_node __an(*this);
1059           return _M_insert_unique_(__pos, std::forward<_Arg>(__x), __an);
1060         }
1061
1062       template<typename _Arg, typename _NodeGen>
1063         iterator
1064         _M_insert_equal_(const_iterator __pos, _Arg&& __x, _NodeGen&);
1065
1066       template<typename _Arg>
1067         iterator
1068         _M_insert_equal_(const_iterator __pos, _Arg&& __x)
1069         {
1070           _Alloc_node __an(*this);
1071           return _M_insert_equal_(__pos, std::forward<_Arg>(__x), __an);
1072         }
1073
1074       template<typename... _Args>
1075         pair<iterator, bool>
1076         _M_emplace_unique(_Args&&... __args);
1077
1078       template<typename... _Args>
1079         iterator
1080         _M_emplace_equal(_Args&&... __args);
1081
1082       template<typename... _Args>
1083         iterator
1084         _M_emplace_hint_unique(const_iterator __pos, _Args&&... __args);
1085
1086       template<typename... _Args>
1087         iterator
1088         _M_emplace_hint_equal(const_iterator __pos, _Args&&... __args);
1089
1090       template<typename _Iter>
1091         using __same_value_type
1092           = is_same<value_type, typename iterator_traits<_Iter>::value_type>;
1093
1094       template<typename _InputIterator>
1095         __enable_if_t<__same_value_type<_InputIterator>::value>
1096         _M_insert_range_unique(_InputIterator __first, _InputIterator __last)
1097         {
1098           _Alloc_node __an(*this);
1099           for (; __first != __last; ++__first)
1100             _M_insert_unique_(end(), *__first, __an);
1101         }
1102
1103       template<typename _InputIterator>
1104         __enable_if_t<!__same_value_type<_InputIterator>::value>
1105         _M_insert_range_unique(_InputIterator __first, _InputIterator __last)
1106         {
1107           for (; __first != __last; ++__first)
1108             _M_emplace_unique(*__first);
1109         }
1110
1111       template<typename _InputIterator>
1112         __enable_if_t<__same_value_type<_InputIterator>::value>
1113         _M_insert_range_equal(_InputIterator __first, _InputIterator __last)
1114         {
1115           _Alloc_node __an(*this);
1116           for (; __first != __last; ++__first)
1117             _M_insert_equal_(end(), *__first, __an);
1118         }
1119
1120       template<typename _InputIterator>
1121         __enable_if_t<!__same_value_type<_InputIterator>::value>
1122         _M_insert_range_equal(_InputIterator __first, _InputIterator __last)
1123         {
1124           for (; __first != __last; ++__first)
1125             _M_emplace_equal(*__first);
1126         }
1127 #else
1128       pair<iterator, bool>
1129       _M_insert_unique(const value_type& __x);
1130
1131       iterator
1132       _M_insert_equal(const value_type& __x);
1133
1134       template<typename _NodeGen>
1135         iterator
1136         _M_insert_unique_(const_iterator __pos, const value_type& __x,
1137                           _NodeGen&);
1138
1139       iterator
1140       _M_insert_unique_(const_iterator __pos, const value_type& __x)
1141       {
1142         _Alloc_node __an(*this);
1143         return _M_insert_unique_(__pos, __x, __an);
1144       }
1145
1146       template<typename _NodeGen>
1147         iterator
1148         _M_insert_equal_(const_iterator __pos, const value_type& __x,
1149                          _NodeGen&);
1150       iterator
1151       _M_insert_equal_(const_iterator __pos, const value_type& __x)
1152       {
1153         _Alloc_node __an(*this);
1154         return _M_insert_equal_(__pos, __x, __an);
1155       }
1156
1157       template<typename _InputIterator>
1158         void
1159         _M_insert_range_unique(_InputIterator __first, _InputIterator __last)
1160         {
1161           _Alloc_node __an(*this);
1162           for (; __first != __last; ++__first)
1163             _M_insert_unique_(end(), *__first, __an);
1164         }
1165
1166       template<typename _InputIterator>
1167         void
1168         _M_insert_range_equal(_InputIterator __first, _InputIterator __last)
1169         {
1170           _Alloc_node __an(*this);
1171           for (; __first != __last; ++__first)
1172             _M_insert_equal_(end(), *__first, __an);
1173         }
1174 #endif
1175
1176     private:
1177       void
1178       _M_erase_aux(const_iterator __position);
1179
1180       void
1181       _M_erase_aux(const_iterator __first, const_iterator __last);
1182
1183     public:
1184 #if __cplusplus >= 201103L
1185       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1186       // DR 130. Associative erase should return an iterator.
1187       _GLIBCXX_ABI_TAG_CXX11
1188       iterator
1189       erase(const_iterator __position)
1190       {
1191         __glibcxx_assert(__position != end());
1192         const_iterator __result = __position;
1193         ++__result;
1194         _M_erase_aux(__position);
1195         return __result._M_const_cast();
1196       }
1197
1198       // LWG 2059.
1199       _GLIBCXX_ABI_TAG_CXX11
1200       iterator
1201       erase(iterator __position)
1202       {
1203         __glibcxx_assert(__position != end());
1204         iterator __result = __position;
1205         ++__result;
1206         _M_erase_aux(__position);
1207         return __result;
1208       }
1209 #else
1210       void
1211       erase(iterator __position)
1212       {
1213         __glibcxx_assert(__position != end());
1214         _M_erase_aux(__position);
1215       }
1216
1217       void
1218       erase(const_iterator __position)
1219       {
1220         __glibcxx_assert(__position != end());
1221         _M_erase_aux(__position);
1222       }
1223 #endif
1224
1225       size_type
1226       erase(const key_type& __x);
1227
1228 #if __cplusplus >= 201103L
1229       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1230       // DR 130. Associative erase should return an iterator.
1231       _GLIBCXX_ABI_TAG_CXX11
1232       iterator
1233       erase(const_iterator __first, const_iterator __last)
1234       {
1235         _M_erase_aux(__first, __last);
1236         return __last._M_const_cast();
1237       }
1238 #else
1239       void
1240       erase(iterator __first, iterator __last)
1241       { _M_erase_aux(__first, __last); }
1242
1243       void
1244       erase(const_iterator __first, const_iterator __last)
1245       { _M_erase_aux(__first, __last); }
1246 #endif
1247
1248       void
1249       clear() _GLIBCXX_NOEXCEPT
1250       {
1251         _M_erase(_M_begin());
1252         _M_impl._M_reset();
1253       }
1254
1255       // Set operations.
1256       iterator
1257       find(const key_type& __k);
1258
1259       const_iterator
1260       find(const key_type& __k) const;
1261
1262       size_type
1263       count(const key_type& __k) const;
1264
1265       iterator
1266       lower_bound(const key_type& __k)
1267       { return _M_lower_bound(_M_begin(), _M_end(), __k); }
1268
1269       const_iterator
1270       lower_bound(const key_type& __k) const
1271       { return _M_lower_bound(_M_begin(), _M_end(), __k); }
1272
1273       iterator
1274       upper_bound(const key_type& __k)
1275       { return _M_upper_bound(_M_begin(), _M_end(), __k); }
1276
1277       const_iterator
1278       upper_bound(const key_type& __k) const
1279       { return _M_upper_bound(_M_begin(), _M_end(), __k); }
1280
1281       pair<iterator, iterator>
1282       equal_range(const key_type& __k);
1283
1284       pair<const_iterator, const_iterator>
1285       equal_range(const key_type& __k) const;
1286
1287 #if __cplusplus >= 201402L
1288       template<typename _Kt,
1289                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1290         iterator
1291         _M_find_tr(const _Kt& __k)
1292         {
1293           const _Rb_tree* __const_this = this;
1294           return __const_this->_M_find_tr(__k)._M_const_cast();
1295         }
1296
1297       template<typename _Kt,
1298                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1299         const_iterator
1300         _M_find_tr(const _Kt& __k) const
1301         {
1302           auto __j = _M_lower_bound_tr(__k);
1303           if (__j != end() && _M_impl._M_key_compare(__k, _S_key(__j._M_node)))
1304             __j = end();
1305           return __j;
1306         }
1307
1308       template<typename _Kt,
1309                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1310         size_type
1311         _M_count_tr(const _Kt& __k) const
1312         {
1313           auto __p = _M_equal_range_tr(__k);
1314           return std::distance(__p.first, __p.second);
1315         }
1316
1317       template<typename _Kt,
1318                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1319         iterator
1320         _M_lower_bound_tr(const _Kt& __k)
1321         {
1322           const _Rb_tree* __const_this = this;
1323           return __const_this->_M_lower_bound_tr(__k)._M_const_cast();
1324         }
1325
1326       template<typename _Kt,
1327                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1328         const_iterator
1329         _M_lower_bound_tr(const _Kt& __k) const
1330         {
1331           auto __x = _M_begin();
1332           auto __y = _M_end();
1333           while (__x != 0)
1334             if (!_M_impl._M_key_compare(_S_key(__x), __k))
1335               {
1336                 __y = __x;
1337                 __x = _S_left(__x);
1338               }
1339             else
1340               __x = _S_right(__x);
1341           return const_iterator(__y);
1342         }
1343
1344       template<typename _Kt,
1345                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1346         iterator
1347         _M_upper_bound_tr(const _Kt& __k)
1348         {
1349           const _Rb_tree* __const_this = this;
1350           return __const_this->_M_upper_bound_tr(__k)._M_const_cast();
1351         }
1352
1353       template<typename _Kt,
1354                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1355         const_iterator
1356         _M_upper_bound_tr(const _Kt& __k) const
1357         {
1358           auto __x = _M_begin();
1359           auto __y = _M_end();
1360           while (__x != 0)
1361             if (_M_impl._M_key_compare(__k, _S_key(__x)))
1362               {
1363                 __y = __x;
1364                 __x = _S_left(__x);
1365               }
1366             else
1367               __x = _S_right(__x);
1368           return const_iterator(__y);
1369         }
1370
1371       template<typename _Kt,
1372                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1373         pair<iterator, iterator>
1374         _M_equal_range_tr(const _Kt& __k)
1375         {
1376           const _Rb_tree* __const_this = this;
1377           auto __ret = __const_this->_M_equal_range_tr(__k);
1378           return { __ret.first._M_const_cast(), __ret.second._M_const_cast() };
1379         }
1380
1381       template<typename _Kt,
1382                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
1383         pair<const_iterator, const_iterator>
1384         _M_equal_range_tr(const _Kt& __k) const
1385         {
1386           auto __low = _M_lower_bound_tr(__k);
1387           auto __high = __low;
1388           auto& __cmp = _M_impl._M_key_compare;
1389           while (__high != end() && !__cmp(__k, _S_key(__high._M_node)))
1390             ++__high;
1391           return { __low, __high };
1392         }
1393 #endif
1394
1395       // Debugging.
1396       bool
1397       __rb_verify() const;
1398
1399 #if __cplusplus >= 201103L
1400       _Rb_tree&
1401       operator=(_Rb_tree&&)
1402       noexcept(_Alloc_traits::_S_nothrow_move()
1403                && is_nothrow_move_assignable<_Compare>::value);
1404
1405       template<typename _Iterator>
1406         void
1407         _M_assign_unique(_Iterator, _Iterator);
1408
1409       template<typename _Iterator>
1410         void
1411         _M_assign_equal(_Iterator, _Iterator);
1412
1413     private:
1414       // Move elements from container with equal allocator.
1415       void
1416       _M_move_data(_Rb_tree& __x, true_type)
1417       { _M_impl._M_move_data(__x._M_impl); }
1418
1419       // Move elements from container with possibly non-equal allocator,
1420       // which might result in a copy not a move.
1421       void
1422       _M_move_data(_Rb_tree&, false_type);
1423
1424       // Move assignment from container with equal allocator.
1425       void
1426       _M_move_assign(_Rb_tree&, true_type);
1427
1428       // Move assignment from container with possibly non-equal allocator,
1429       // which might result in a copy not a move.
1430       void
1431       _M_move_assign(_Rb_tree&, false_type);
1432 #endif
1433
1434 #if __glibcxx_node_extract // >= C++17
1435     public:
1436       /// Re-insert an extracted node.
1437       insert_return_type
1438       _M_reinsert_node_unique(node_type&& __nh)
1439       {
1440         insert_return_type __ret;
1441         if (__nh.empty())
1442           __ret.position = end();
1443         else
1444           {
1445             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1446
1447             auto __res = _M_get_insert_unique_pos(__nh._M_key());
1448             if (__res.second)
1449               {
1450                 __ret.position
1451                   = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1452                 __nh.release();
1453                 __ret.inserted = true;
1454               }
1455             else
1456               {
1457                 __ret.node = std::move(__nh);
1458                 __ret.position = iterator(__res.first);
1459                 __ret.inserted = false;
1460               }
1461           }
1462         return __ret;
1463       }
1464
1465       /// Re-insert an extracted node.
1466       iterator
1467       _M_reinsert_node_equal(node_type&& __nh)
1468       {
1469         iterator __ret;
1470         if (__nh.empty())
1471           __ret = end();
1472         else
1473           {
1474             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1475             auto __res = _M_get_insert_equal_pos(__nh._M_key());
1476             if (__res.second)
1477               __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1478             else
1479               __ret = _M_insert_equal_lower_node(__nh._M_ptr);
1480             __nh.release();
1481           }
1482         return __ret;
1483       }
1484
1485       /// Re-insert an extracted node.
1486       iterator
1487       _M_reinsert_node_hint_unique(const_iterator __hint, node_type&& __nh)
1488       {
1489         iterator __ret;
1490         if (__nh.empty())
1491           __ret = end();
1492         else
1493           {
1494             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1495             auto __res = _M_get_insert_hint_unique_pos(__hint, __nh._M_key());
1496             if (__res.second)
1497               {
1498                 __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1499                 __nh.release();
1500               }
1501             else
1502               __ret = iterator(__res.first);
1503           }
1504         return __ret;
1505       }
1506
1507       /// Re-insert an extracted node.
1508       iterator
1509       _M_reinsert_node_hint_equal(const_iterator __hint, node_type&& __nh)
1510       {
1511         iterator __ret;
1512         if (__nh.empty())
1513           __ret = end();
1514         else
1515           {
1516             __glibcxx_assert(_M_get_Node_allocator() == *__nh._M_alloc);
1517             auto __res = _M_get_insert_hint_equal_pos(__hint, __nh._M_key());
1518             if (__res.second)
1519               __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
1520             else
1521               __ret = _M_insert_equal_lower_node(__nh._M_ptr);
1522             __nh.release();
1523           }
1524         return __ret;
1525       }
1526
1527       /// Extract a node.
1528       node_type
1529       extract(const_iterator __pos)
1530       {
1531         auto __ptr = _Rb_tree_rebalance_for_erase(
1532             __pos._M_const_cast()._M_node, _M_impl._M_header);
1533         --_M_impl._M_node_count;
1534         return { static_cast<_Link_type>(__ptr), _M_get_Node_allocator() };
1535       }
1536
1537       /// Extract a node.
1538       node_type
1539       extract(const key_type& __k)
1540       {
1541         node_type __nh;
1542         auto __pos = find(__k);
1543         if (__pos != end())
1544           __nh = extract(const_iterator(__pos));
1545         return __nh;
1546       }
1547
1548       template<typename _Compare2>
1549         using _Compatible_tree
1550           = _Rb_tree<_Key, _Val, _KeyOfValue, _Compare2, _Alloc>;
1551
1552       template<typename, typename>
1553         friend struct _Rb_tree_merge_helper;
1554
1555       /// Merge from a compatible container into one with unique keys.
1556       template<typename _Compare2>
1557         void
1558         _M_merge_unique(_Compatible_tree<_Compare2>& __src) noexcept
1559         {
1560           using _Merge_helper = _Rb_tree_merge_helper<_Rb_tree, _Compare2>;
1561           for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1562             {
1563               auto __pos = __i++;
1564               auto __res = _M_get_insert_unique_pos(_KeyOfValue()(*__pos));
1565               if (__res.second)
1566                 {
1567                   auto& __src_impl = _Merge_helper::_S_get_impl(__src);
1568                   auto __ptr = _Rb_tree_rebalance_for_erase(
1569                       __pos._M_node, __src_impl._M_header);
1570                   --__src_impl._M_node_count;
1571                   _M_insert_node(__res.first, __res.second,
1572                                  static_cast<_Link_type>(__ptr));
1573                 }
1574             }
1575         }
1576
1577       /// Merge from a compatible container into one with equivalent keys.
1578       template<typename _Compare2>
1579         void
1580         _M_merge_equal(_Compatible_tree<_Compare2>& __src) noexcept
1581         {
1582           using _Merge_helper = _Rb_tree_merge_helper<_Rb_tree, _Compare2>;
1583           for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1584             {
1585               auto __pos = __i++;
1586               auto __res = _M_get_insert_equal_pos(_KeyOfValue()(*__pos));
1587               if (__res.second)
1588                 {
1589                   auto& __src_impl = _Merge_helper::_S_get_impl(__src);
1590                   auto __ptr = _Rb_tree_rebalance_for_erase(
1591                       __pos._M_node, __src_impl._M_header);
1592                   --__src_impl._M_node_count;
1593                   _M_insert_node(__res.first, __res.second,
1594                                  static_cast<_Link_type>(__ptr));
1595                 }
1596             }
1597         }
1598 #endif // C++17 node_extract
1599
1600       friend bool
1601       operator==(const _Rb_tree& __x, const _Rb_tree& __y)
1602       {
1603         return __x.size() == __y.size()
1604           && std::equal(__x.begin(), __x.end(), __y.begin());
1605       }
1606
1607 #if __cpp_lib_three_way_comparison
1608       friend auto
1609       operator<=>(const _Rb_tree& __x, const _Rb_tree& __y)
1610       {
1611         if constexpr (requires { typename __detail::__synth3way_t<_Val>; })
1612           return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
1613                                                         __y.begin(), __y.end(),
1614                                                         __detail::__synth3way);
1615       }
1616 #else
1617       friend bool
1618       operator<(const _Rb_tree& __x, const _Rb_tree& __y)
1619       {
1620         return std::lexicographical_compare(__x.begin(), __x.end(),
1621                                             __y.begin(), __y.end());
1622       }
1623 #endif
1624
1625     private:
1626 #if __cplusplus >= 201103L
1627       // An RAII _Node handle
1628       struct _Auto_node
1629       {
1630         template<typename... _Args>
1631           _Auto_node(_Rb_tree& __t, _Args&&... __args)
1632           : _M_t(__t),
1633             _M_node(__t._M_create_node(std::forward<_Args>(__args)...))
1634           { }
1635
1636         ~_Auto_node()
1637         {
1638           if (_M_node)
1639             _M_t._M_drop_node(_M_node);
1640         }
1641
1642         _Auto_node(_Auto_node&& __n)
1643         : _M_t(__n._M_t), _M_node(__n._M_node)
1644         { __n._M_node = nullptr; }
1645
1646         const _Key&
1647         _M_key() const
1648         { return _S_key(_M_node); }
1649
1650         iterator
1651         _M_insert(pair<_Base_ptr, _Base_ptr> __p)
1652         {
1653           auto __it = _M_t._M_insert_node(__p.first, __p.second, _M_node);
1654           _M_node = nullptr;
1655           return __it;
1656         }
1657
1658         iterator
1659         _M_insert_equal_lower()
1660         {
1661           auto __it = _M_t._M_insert_equal_lower_node(_M_node);
1662           _M_node = nullptr;
1663           return __it;
1664         }
1665
1666         _Rb_tree& _M_t;
1667         _Link_type _M_node;
1668       };
1669 #endif // C++11
1670     };
1671
1672   template<typename _Key, typename _Val, typename _KeyOfValue,
1673            typename _Compare, typename _Alloc>
1674     inline void
1675     swap(_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
1676          _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __y)
1677     { __x.swap(__y); }
1678
1679 #if __cplusplus >= 201103L
1680   template<typename _Key, typename _Val, typename _KeyOfValue,
1681            typename _Compare, typename _Alloc>
1682     void
1683     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1684     _M_move_data(_Rb_tree& __x, false_type)
1685     {
1686       if (_M_get_Node_allocator() == __x._M_get_Node_allocator())
1687         _M_move_data(__x, true_type());
1688       else
1689         {
1690           constexpr bool __move = !__move_if_noexcept_cond<value_type>::value;
1691           _Alloc_node __an(*this);
1692           _M_root() = _M_copy<__move>(__x, __an);
1693           if _GLIBCXX17_CONSTEXPR (__move)
1694             __x.clear();
1695         }
1696     }
1697
1698   template<typename _Key, typename _Val, typename _KeyOfValue,
1699            typename _Compare, typename _Alloc>
1700     inline void
1701     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1702     _M_move_assign(_Rb_tree& __x, true_type)
1703     {
1704       clear();
1705       if (__x._M_root() != nullptr)
1706         _M_move_data(__x, true_type());
1707       std::__alloc_on_move(_M_get_Node_allocator(),
1708                            __x._M_get_Node_allocator());
1709     }
1710
1711   template<typename _Key, typename _Val, typename _KeyOfValue,
1712            typename _Compare, typename _Alloc>
1713     void
1714     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1715     _M_move_assign(_Rb_tree& __x, false_type)
1716     {
1717       if (_M_get_Node_allocator() == __x._M_get_Node_allocator())
1718         return _M_move_assign(__x, true_type{});
1719
1720       // Try to move each node reusing existing nodes and copying __x nodes
1721       // structure.
1722       _Reuse_or_alloc_node __roan(*this);
1723       _M_impl._M_reset();
1724       if (__x._M_root() != nullptr)
1725         {
1726           _M_root() = _M_copy<__as_rvalue>(__x, __roan);
1727           __x.clear();
1728         }
1729     }
1730
1731   template<typename _Key, typename _Val, typename _KeyOfValue,
1732            typename _Compare, typename _Alloc>
1733     inline _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&
1734     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1735     operator=(_Rb_tree&& __x)
1736     noexcept(_Alloc_traits::_S_nothrow_move()
1737              && is_nothrow_move_assignable<_Compare>::value)
1738     {
1739       _M_impl._M_key_compare = std::move(__x._M_impl._M_key_compare);
1740       _M_move_assign(__x, __bool_constant<_Alloc_traits::_S_nothrow_move()>());
1741       return *this;
1742     }
1743
1744   template<typename _Key, typename _Val, typename _KeyOfValue,
1745            typename _Compare, typename _Alloc>
1746     template<typename _Iterator>
1747       void
1748       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1749       _M_assign_unique(_Iterator __first, _Iterator __last)
1750       {
1751         _Reuse_or_alloc_node __roan(*this);
1752         _M_impl._M_reset();
1753         for (; __first != __last; ++__first)
1754           _M_insert_unique_(end(), *__first, __roan);
1755       }
1756
1757   template<typename _Key, typename _Val, typename _KeyOfValue,
1758            typename _Compare, typename _Alloc>
1759     template<typename _Iterator>
1760       void
1761       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1762       _M_assign_equal(_Iterator __first, _Iterator __last)
1763       {
1764         _Reuse_or_alloc_node __roan(*this);
1765         _M_impl._M_reset();
1766         for (; __first != __last; ++__first)
1767           _M_insert_equal_(end(), *__first, __roan);
1768       }
1769 #endif
1770
1771   template<typename _Key, typename _Val, typename _KeyOfValue,
1772            typename _Compare, typename _Alloc>
1773     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&
1774     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1775     operator=(const _Rb_tree& __x)
1776     {
1777       if (this != std::__addressof(__x))
1778         {
1779           // Note that _Key may be a constant type.
1780 #if __cplusplus >= 201103L
1781           if (_Alloc_traits::_S_propagate_on_copy_assign())
1782             {
1783               auto& __this_alloc = this->_M_get_Node_allocator();
1784               auto& __that_alloc = __x._M_get_Node_allocator();
1785               if (!_Alloc_traits::_S_always_equal()
1786                   && __this_alloc != __that_alloc)
1787                 {
1788                   // Replacement allocator cannot free existing storage, we need
1789                   // to erase nodes first.
1790                   clear();
1791                   std::__alloc_on_copy(__this_alloc, __that_alloc);
1792                 }
1793             }
1794 #endif
1795
1796           _Reuse_or_alloc_node __roan(*this);
1797           _M_impl._M_reset();
1798           _M_impl._M_key_compare = __x._M_impl._M_key_compare;
1799           if (__x._M_root() != 0)
1800             _M_root() = _M_copy<__as_lvalue>(__x, __roan);
1801         }
1802
1803       return *this;
1804     }
1805
1806   template<typename _Key, typename _Val, typename _KeyOfValue,
1807            typename _Compare, typename _Alloc>
1808 #if __cplusplus >= 201103L
1809     template<typename _Arg, typename _NodeGen>
1810 #else
1811     template<typename _NodeGen>
1812 #endif
1813       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1814       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1815       _M_insert_(_Base_ptr __x, _Base_ptr __p,
1816 #if __cplusplus >= 201103L
1817                  _Arg&& __v,
1818 #else
1819                  const _Val& __v,
1820 #endif
1821                  _NodeGen& __node_gen)
1822       {
1823         bool __insert_left = (__x != 0 || __p == _M_end()
1824                               || _M_impl._M_key_compare(_KeyOfValue()(__v),
1825                                                         _S_key(__p)));
1826
1827         _Link_type __z = __node_gen(_GLIBCXX_FORWARD(_Arg, __v));
1828
1829         _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
1830                                       this->_M_impl._M_header);
1831         ++_M_impl._M_node_count;
1832         return iterator(__z);
1833       }
1834
1835   template<typename _Key, typename _Val, typename _KeyOfValue,
1836            typename _Compare, typename _Alloc>
1837 #if __cplusplus >= 201103L
1838     template<typename _Arg>
1839 #endif
1840     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1841     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1842 #if __cplusplus >= 201103L
1843     _M_insert_lower(_Base_ptr __p, _Arg&& __v)
1844 #else
1845     _M_insert_lower(_Base_ptr __p, const _Val& __v)
1846 #endif
1847     {
1848       bool __insert_left = (__p == _M_end()
1849                             || !_M_impl._M_key_compare(_S_key(__p),
1850                                                        _KeyOfValue()(__v)));
1851
1852       _Link_type __z = _M_create_node(_GLIBCXX_FORWARD(_Arg, __v));
1853
1854       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
1855                                     this->_M_impl._M_header);
1856       ++_M_impl._M_node_count;
1857       return iterator(__z);
1858     }
1859
1860   template<typename _Key, typename _Val, typename _KeyOfValue,
1861            typename _Compare, typename _Alloc>
1862 #if __cplusplus >= 201103L
1863     template<typename _Arg>
1864 #endif
1865     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
1866     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1867 #if __cplusplus >= 201103L
1868     _M_insert_equal_lower(_Arg&& __v)
1869 #else
1870     _M_insert_equal_lower(const _Val& __v)
1871 #endif
1872     {
1873       _Link_type __x = _M_begin();
1874       _Base_ptr __y = _M_end();
1875       while (__x != 0)
1876         {
1877           __y = __x;
1878           __x = !_M_impl._M_key_compare(_S_key(__x), _KeyOfValue()(__v)) ?
1879                 _S_left(__x) : _S_right(__x);
1880         }
1881       return _M_insert_lower(__y, _GLIBCXX_FORWARD(_Arg, __v));
1882     }
1883
1884   template<typename _Key, typename _Val, typename _KoV,
1885            typename _Compare, typename _Alloc>
1886     template<bool _MoveValues, typename _NodeGen>
1887       typename _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::_Link_type
1888       _Rb_tree<_Key, _Val, _KoV, _Compare, _Alloc>::
1889       _M_copy(_Link_type __x, _Base_ptr __p, _NodeGen& __node_gen)
1890       {
1891         // Structural copy. __x and __p must be non-null.
1892         _Link_type __top = _M_clone_node<_MoveValues>(__x, __node_gen);
1893         __top->_M_parent = __p;
1894
1895         __try
1896           {
1897             if (__x->_M_right)
1898               __top->_M_right =
1899                 _M_copy<_MoveValues>(_S_right(__x), __top, __node_gen);
1900             __p = __top;
1901             __x = _S_left(__x);
1902
1903             while (__x != 0)
1904               {
1905                 _Link_type __y = _M_clone_node<_MoveValues>(__x, __node_gen);
1906                 __p->_M_left = __y;
1907                 __y->_M_parent = __p;
1908                 if (__x->_M_right)
1909                   __y->_M_right = _M_copy<_MoveValues>(_S_right(__x),
1910                                                        __y, __node_gen);
1911                 __p = __y;
1912                 __x = _S_left(__x);
1913               }
1914           }
1915         __catch(...)
1916           {
1917             _M_erase(__top);
1918             __throw_exception_again;
1919           }
1920         return __top;
1921       }
1922
1923   template<typename _Key, typename _Val, typename _KeyOfValue,
1924            typename _Compare, typename _Alloc>
1925     void
1926     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1927     _M_erase(_Link_type __x)
1928     {
1929       // Erase without rebalancing.
1930       while (__x != 0)
1931         {
1932           _M_erase(_S_right(__x));
1933           _Link_type __y = _S_left(__x);
1934           _M_drop_node(__x);
1935           __x = __y;
1936         }
1937     }
1938
1939   template<typename _Key, typename _Val, typename _KeyOfValue,
1940            typename _Compare, typename _Alloc>
1941     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1942                       _Compare, _Alloc>::iterator
1943     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1944     _M_lower_bound(_Link_type __x, _Base_ptr __y,
1945                    const _Key& __k)
1946     {
1947       while (__x != 0)
1948         if (!_M_impl._M_key_compare(_S_key(__x), __k))
1949           __y = __x, __x = _S_left(__x);
1950         else
1951           __x = _S_right(__x);
1952       return iterator(__y);
1953     }
1954
1955   template<typename _Key, typename _Val, typename _KeyOfValue,
1956            typename _Compare, typename _Alloc>
1957     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1958                       _Compare, _Alloc>::const_iterator
1959     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1960     _M_lower_bound(_Const_Link_type __x, _Const_Base_ptr __y,
1961                    const _Key& __k) const
1962     {
1963       while (__x != 0)
1964         if (!_M_impl._M_key_compare(_S_key(__x), __k))
1965           __y = __x, __x = _S_left(__x);
1966         else
1967           __x = _S_right(__x);
1968       return const_iterator(__y);
1969     }
1970
1971   template<typename _Key, typename _Val, typename _KeyOfValue,
1972            typename _Compare, typename _Alloc>
1973     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1974                       _Compare, _Alloc>::iterator
1975     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1976     _M_upper_bound(_Link_type __x, _Base_ptr __y,
1977                    const _Key& __k)
1978     {
1979       while (__x != 0)
1980         if (_M_impl._M_key_compare(__k, _S_key(__x)))
1981           __y = __x, __x = _S_left(__x);
1982         else
1983           __x = _S_right(__x);
1984       return iterator(__y);
1985     }
1986
1987   template<typename _Key, typename _Val, typename _KeyOfValue,
1988            typename _Compare, typename _Alloc>
1989     typename _Rb_tree<_Key, _Val, _KeyOfValue,
1990                       _Compare, _Alloc>::const_iterator
1991     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
1992     _M_upper_bound(_Const_Link_type __x, _Const_Base_ptr __y,
1993                    const _Key& __k) const
1994     {
1995       while (__x != 0)
1996         if (_M_impl._M_key_compare(__k, _S_key(__x)))
1997           __y = __x, __x = _S_left(__x);
1998         else
1999           __x = _S_right(__x);
2000       return const_iterator(__y);
2001     }
2002
2003   template<typename _Key, typename _Val, typename _KeyOfValue,
2004            typename _Compare, typename _Alloc>
2005     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2006                            _Compare, _Alloc>::iterator,
2007          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2008                            _Compare, _Alloc>::iterator>
2009     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2010     equal_range(const _Key& __k)
2011     {
2012       _Link_type __x = _M_begin();
2013       _Base_ptr __y = _M_end();
2014       while (__x != 0)
2015         {
2016           if (_M_impl._M_key_compare(_S_key(__x), __k))
2017             __x = _S_right(__x);
2018           else if (_M_impl._M_key_compare(__k, _S_key(__x)))
2019             __y = __x, __x = _S_left(__x);
2020           else
2021             {
2022               _Link_type __xu(__x);
2023               _Base_ptr __yu(__y);
2024               __y = __x, __x = _S_left(__x);
2025               __xu = _S_right(__xu);
2026               return pair<iterator,
2027                           iterator>(_M_lower_bound(__x, __y, __k),
2028                                     _M_upper_bound(__xu, __yu, __k));
2029             }
2030         }
2031       return pair<iterator, iterator>(iterator(__y),
2032                                       iterator(__y));
2033     }
2034
2035   template<typename _Key, typename _Val, typename _KeyOfValue,
2036            typename _Compare, typename _Alloc>
2037     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2038                            _Compare, _Alloc>::const_iterator,
2039          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2040                            _Compare, _Alloc>::const_iterator>
2041     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2042     equal_range(const _Key& __k) const
2043     {
2044       _Const_Link_type __x = _M_begin();
2045       _Const_Base_ptr __y = _M_end();
2046       while (__x != 0)
2047         {
2048           if (_M_impl._M_key_compare(_S_key(__x), __k))
2049             __x = _S_right(__x);
2050           else if (_M_impl._M_key_compare(__k, _S_key(__x)))
2051             __y = __x, __x = _S_left(__x);
2052           else
2053             {
2054               _Const_Link_type __xu(__x);
2055               _Const_Base_ptr __yu(__y);
2056               __y = __x, __x = _S_left(__x);
2057               __xu = _S_right(__xu);
2058               return pair<const_iterator,
2059                           const_iterator>(_M_lower_bound(__x, __y, __k),
2060                                           _M_upper_bound(__xu, __yu, __k));
2061             }
2062         }
2063       return pair<const_iterator, const_iterator>(const_iterator(__y),
2064                                                   const_iterator(__y));
2065     }
2066
2067   template<typename _Key, typename _Val, typename _KeyOfValue,
2068            typename _Compare, typename _Alloc>
2069     void
2070     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2071     swap(_Rb_tree& __t)
2072     _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
2073     {
2074       if (_M_root() == 0)
2075         {
2076           if (__t._M_root() != 0)
2077             _M_impl._M_move_data(__t._M_impl);
2078         }
2079       else if (__t._M_root() == 0)
2080         __t._M_impl._M_move_data(_M_impl);
2081       else
2082         {
2083           std::swap(_M_root(),__t._M_root());
2084           std::swap(_M_leftmost(),__t._M_leftmost());
2085           std::swap(_M_rightmost(),__t._M_rightmost());
2086
2087           _M_root()->_M_parent = _M_end();
2088           __t._M_root()->_M_parent = __t._M_end();
2089           std::swap(this->_M_impl._M_node_count, __t._M_impl._M_node_count);
2090         }
2091       // No need to swap header's color as it does not change.
2092       std::swap(this->_M_impl._M_key_compare, __t._M_impl._M_key_compare);
2093
2094       _Alloc_traits::_S_on_swap(_M_get_Node_allocator(),
2095                                 __t._M_get_Node_allocator());
2096     }
2097
2098   template<typename _Key, typename _Val, typename _KeyOfValue,
2099            typename _Compare, typename _Alloc>
2100     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2101                            _Compare, _Alloc>::_Base_ptr,
2102          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2103                            _Compare, _Alloc>::_Base_ptr>
2104     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2105     _M_get_insert_unique_pos(const key_type& __k)
2106     {
2107       typedef pair<_Base_ptr, _Base_ptr> _Res;
2108       _Link_type __x = _M_begin();
2109       _Base_ptr __y = _M_end();
2110       bool __comp = true;
2111       while (__x != 0)
2112         {
2113           __y = __x;
2114           __comp = _M_impl._M_key_compare(__k, _S_key(__x));
2115           __x = __comp ? _S_left(__x) : _S_right(__x);
2116         }
2117       iterator __j = iterator(__y);
2118       if (__comp)
2119         {
2120           if (__j == begin())
2121             return _Res(__x, __y);
2122           else
2123             --__j;
2124         }
2125       if (_M_impl._M_key_compare(_S_key(__j._M_node), __k))
2126         return _Res(__x, __y);
2127       return _Res(__j._M_node, 0);
2128     }
2129
2130   template<typename _Key, typename _Val, typename _KeyOfValue,
2131            typename _Compare, typename _Alloc>
2132     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2133                            _Compare, _Alloc>::_Base_ptr,
2134          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2135                            _Compare, _Alloc>::_Base_ptr>
2136     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2137     _M_get_insert_equal_pos(const key_type& __k)
2138     {
2139       typedef pair<_Base_ptr, _Base_ptr> _Res;
2140       _Link_type __x = _M_begin();
2141       _Base_ptr __y = _M_end();
2142       while (__x != 0)
2143         {
2144           __y = __x;
2145           __x = _M_impl._M_key_compare(__k, _S_key(__x)) ?
2146                 _S_left(__x) : _S_right(__x);
2147         }
2148       return _Res(__x, __y);
2149     }
2150
2151   template<typename _Key, typename _Val, typename _KeyOfValue,
2152            typename _Compare, typename _Alloc>
2153 #if __cplusplus >= 201103L
2154     template<typename _Arg>
2155 #endif
2156     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2157                            _Compare, _Alloc>::iterator, bool>
2158     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2159 #if __cplusplus >= 201103L
2160     _M_insert_unique(_Arg&& __v)
2161 #else
2162     _M_insert_unique(const _Val& __v)
2163 #endif
2164     {
2165       typedef pair<iterator, bool> _Res;
2166       pair<_Base_ptr, _Base_ptr> __res
2167         = _M_get_insert_unique_pos(_KeyOfValue()(__v));
2168
2169       if (__res.second)
2170         {
2171           _Alloc_node __an(*this);
2172           return _Res(_M_insert_(__res.first, __res.second,
2173                                  _GLIBCXX_FORWARD(_Arg, __v), __an),
2174                       true);
2175         }
2176
2177       return _Res(iterator(__res.first), false);
2178     }
2179
2180   template<typename _Key, typename _Val, typename _KeyOfValue,
2181            typename _Compare, typename _Alloc>
2182 #if __cplusplus >= 201103L
2183     template<typename _Arg>
2184 #endif
2185     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2186     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2187 #if __cplusplus >= 201103L
2188     _M_insert_equal(_Arg&& __v)
2189 #else
2190     _M_insert_equal(const _Val& __v)
2191 #endif
2192     {
2193       pair<_Base_ptr, _Base_ptr> __res
2194         = _M_get_insert_equal_pos(_KeyOfValue()(__v));
2195       _Alloc_node __an(*this);
2196       return _M_insert_(__res.first, __res.second,
2197                         _GLIBCXX_FORWARD(_Arg, __v), __an);
2198     }
2199
2200   template<typename _Key, typename _Val, typename _KeyOfValue,
2201            typename _Compare, typename _Alloc>
2202     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2203                            _Compare, _Alloc>::_Base_ptr,
2204          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2205                            _Compare, _Alloc>::_Base_ptr>
2206     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2207     _M_get_insert_hint_unique_pos(const_iterator __position,
2208                                   const key_type& __k)
2209     {
2210       iterator __pos = __position._M_const_cast();
2211       typedef pair<_Base_ptr, _Base_ptr> _Res;
2212
2213       // end()
2214       if (__pos._M_node == _M_end())
2215         {
2216           if (size() > 0
2217               && _M_impl._M_key_compare(_S_key(_M_rightmost()), __k))
2218             return _Res(0, _M_rightmost());
2219           else
2220             return _M_get_insert_unique_pos(__k);
2221         }
2222       else if (_M_impl._M_key_compare(__k, _S_key(__pos._M_node)))
2223         {
2224           // First, try before...
2225           iterator __before = __pos;
2226           if (__pos._M_node == _M_leftmost()) // begin()
2227             return _Res(_M_leftmost(), _M_leftmost());
2228           else if (_M_impl._M_key_compare(_S_key((--__before)._M_node), __k))
2229             {
2230               if (_S_right(__before._M_node) == 0)
2231                 return _Res(0, __before._M_node);
2232               else
2233                 return _Res(__pos._M_node, __pos._M_node);
2234             }
2235           else
2236             return _M_get_insert_unique_pos(__k);
2237         }
2238       else if (_M_impl._M_key_compare(_S_key(__pos._M_node), __k))
2239         {
2240           // ... then try after.
2241           iterator __after = __pos;
2242           if (__pos._M_node == _M_rightmost())
2243             return _Res(0, _M_rightmost());
2244           else if (_M_impl._M_key_compare(__k, _S_key((++__after)._M_node)))
2245             {
2246               if (_S_right(__pos._M_node) == 0)
2247                 return _Res(0, __pos._M_node);
2248               else
2249                 return _Res(__after._M_node, __after._M_node);
2250             }
2251           else
2252             return _M_get_insert_unique_pos(__k);
2253         }
2254       else
2255         // Equivalent keys.
2256         return _Res(__pos._M_node, 0);
2257     }
2258
2259   template<typename _Key, typename _Val, typename _KeyOfValue,
2260            typename _Compare, typename _Alloc>
2261 #if __cplusplus >= 201103L
2262     template<typename _Arg, typename _NodeGen>
2263 #else
2264     template<typename _NodeGen>
2265 #endif
2266       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2267       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2268       _M_insert_unique_(const_iterator __position,
2269 #if __cplusplus >= 201103L
2270                         _Arg&& __v,
2271 #else
2272                         const _Val& __v,
2273 #endif
2274                         _NodeGen& __node_gen)
2275     {
2276       pair<_Base_ptr, _Base_ptr> __res
2277         = _M_get_insert_hint_unique_pos(__position, _KeyOfValue()(__v));
2278
2279       if (__res.second)
2280         return _M_insert_(__res.first, __res.second,
2281                           _GLIBCXX_FORWARD(_Arg, __v),
2282                           __node_gen);
2283       return iterator(__res.first);
2284     }
2285
2286   template<typename _Key, typename _Val, typename _KeyOfValue,
2287            typename _Compare, typename _Alloc>
2288     pair<typename _Rb_tree<_Key, _Val, _KeyOfValue,
2289                            _Compare, _Alloc>::_Base_ptr,
2290          typename _Rb_tree<_Key, _Val, _KeyOfValue,
2291                            _Compare, _Alloc>::_Base_ptr>
2292     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2293     _M_get_insert_hint_equal_pos(const_iterator __position, const key_type& __k)
2294     {
2295       iterator __pos = __position._M_const_cast();
2296       typedef pair<_Base_ptr, _Base_ptr> _Res;
2297
2298       // end()
2299       if (__pos._M_node == _M_end())
2300         {
2301           if (size() > 0
2302               && !_M_impl._M_key_compare(__k, _S_key(_M_rightmost())))
2303             return _Res(0, _M_rightmost());
2304           else
2305             return _M_get_insert_equal_pos(__k);
2306         }
2307       else if (!_M_impl._M_key_compare(_S_key(__pos._M_node), __k))
2308         {
2309           // First, try before...
2310           iterator __before = __pos;
2311           if (__pos._M_node == _M_leftmost()) // begin()
2312             return _Res(_M_leftmost(), _M_leftmost());
2313           else if (!_M_impl._M_key_compare(__k, _S_key((--__before)._M_node)))
2314             {
2315               if (_S_right(__before._M_node) == 0)
2316                 return _Res(0, __before._M_node);
2317               else
2318                 return _Res(__pos._M_node, __pos._M_node);
2319             }
2320           else
2321             return _M_get_insert_equal_pos(__k);
2322         }
2323       else
2324         {
2325           // ... then try after.
2326           iterator __after = __pos;
2327           if (__pos._M_node == _M_rightmost())
2328             return _Res(0, _M_rightmost());
2329           else if (!_M_impl._M_key_compare(_S_key((++__after)._M_node), __k))
2330             {
2331               if (_S_right(__pos._M_node) == 0)
2332                 return _Res(0, __pos._M_node);
2333               else
2334                 return _Res(__after._M_node, __after._M_node);
2335             }
2336           else
2337             return _Res(0, 0);
2338         }
2339     }
2340
2341   template<typename _Key, typename _Val, typename _KeyOfValue,
2342            typename _Compare, typename _Alloc>
2343 #if __cplusplus >= 201103L
2344     template<typename _Arg, typename _NodeGen>
2345 #else
2346     template<typename _NodeGen>
2347 #endif
2348       typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator
2349       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2350       _M_insert_equal_(const_iterator __position,
2351 #if __cplusplus >= 201103L
2352                        _Arg&& __v,
2353 #else
2354                        const _Val& __v,
2355 #endif
2356                        _NodeGen& __node_gen)
2357       {
2358         pair<_Base_ptr, _Base_ptr> __res
2359           = _M_get_insert_hint_equal_pos(__position, _KeyOfValue()(__v));
2360
2361         if (__res.second)
2362           return _M_insert_(__res.first, __res.second,
2363                             _GLIBCXX_FORWARD(_Arg, __v),
2364                             __node_gen);
2365
2366         return _M_insert_equal_lower(_GLIBCXX_FORWARD(_Arg, __v));
2367       }
2368
2369 #if __cplusplus >= 201103L
2370   template<typename _Key, typename _Val, typename _KeyOfValue,
2371            typename _Compare, typename _Alloc>
2372     auto
2373     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2374     _M_insert_node(_Base_ptr __x, _Base_ptr __p, _Link_type __z)
2375     -> iterator
2376     {
2377       bool __insert_left = (__x != 0 || __p == _M_end()
2378                             || _M_impl._M_key_compare(_S_key(__z),
2379                                                       _S_key(__p)));
2380
2381       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
2382                                     this->_M_impl._M_header);
2383       ++_M_impl._M_node_count;
2384       return iterator(__z);
2385     }
2386
2387   template<typename _Key, typename _Val, typename _KeyOfValue,
2388            typename _Compare, typename _Alloc>
2389     auto
2390     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2391     _M_insert_lower_node(_Base_ptr __p, _Link_type __z)
2392     -> iterator
2393     {
2394       bool __insert_left = (__p == _M_end()
2395                             || !_M_impl._M_key_compare(_S_key(__p),
2396                                                        _S_key(__z)));
2397
2398       _Rb_tree_insert_and_rebalance(__insert_left, __z, __p,
2399                                     this->_M_impl._M_header);
2400       ++_M_impl._M_node_count;
2401       return iterator(__z);
2402     }
2403
2404   template<typename _Key, typename _Val, typename _KeyOfValue,
2405            typename _Compare, typename _Alloc>
2406     auto
2407     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2408     _M_insert_equal_lower_node(_Link_type __z)
2409     -> iterator
2410     {
2411       _Link_type __x = _M_begin();
2412       _Base_ptr __y = _M_end();
2413       while (__x != 0)
2414         {
2415           __y = __x;
2416           __x = !_M_impl._M_key_compare(_S_key(__x), _S_key(__z)) ?
2417                 _S_left(__x) : _S_right(__x);
2418         }
2419       return _M_insert_lower_node(__y, __z);
2420     }
2421
2422   template<typename _Key, typename _Val, typename _KeyOfValue,
2423            typename _Compare, typename _Alloc>
2424     template<typename... _Args>
2425       auto
2426       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2427       _M_emplace_unique(_Args&&... __args)
2428       -> pair<iterator, bool>
2429       {
2430         _Auto_node __z(*this, std::forward<_Args>(__args)...);
2431         auto __res = _M_get_insert_unique_pos(__z._M_key());
2432         if (__res.second)
2433           return {__z._M_insert(__res), true};
2434         return {iterator(__res.first), false};
2435       }
2436
2437   template<typename _Key, typename _Val, typename _KeyOfValue,
2438            typename _Compare, typename _Alloc>
2439     template<typename... _Args>
2440       auto
2441       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2442       _M_emplace_equal(_Args&&... __args)
2443       -> iterator
2444       {
2445         _Auto_node __z(*this, std::forward<_Args>(__args)...);
2446         auto __res = _M_get_insert_equal_pos(__z._M_key());
2447         return __z._M_insert(__res);
2448       }
2449
2450   template<typename _Key, typename _Val, typename _KeyOfValue,
2451            typename _Compare, typename _Alloc>
2452     template<typename... _Args>
2453       auto
2454       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2455       _M_emplace_hint_unique(const_iterator __pos, _Args&&... __args)
2456       -> iterator
2457       {
2458         _Auto_node __z(*this, std::forward<_Args>(__args)...);
2459         auto __res = _M_get_insert_hint_unique_pos(__pos, __z._M_key());
2460         if (__res.second)
2461           return __z._M_insert(__res);
2462         return iterator(__res.first);
2463       }
2464
2465   template<typename _Key, typename _Val, typename _KeyOfValue,
2466            typename _Compare, typename _Alloc>
2467     template<typename... _Args>
2468       auto
2469       _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2470       _M_emplace_hint_equal(const_iterator __pos, _Args&&... __args)
2471       -> iterator
2472       {
2473         _Auto_node __z(*this, std::forward<_Args>(__args)...);
2474         auto __res = _M_get_insert_hint_equal_pos(__pos, __z._M_key());
2475         if (__res.second)
2476           return __z._M_insert(__res);
2477         return __z._M_insert_equal_lower();
2478       }
2479 #endif
2480
2481
2482   template<typename _Key, typename _Val, typename _KeyOfValue,
2483            typename _Compare, typename _Alloc>
2484     void
2485     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2486     _M_erase_aux(const_iterator __position)
2487     {
2488       _Link_type __y =
2489         static_cast<_Link_type>(_Rb_tree_rebalance_for_erase
2490                                 (const_cast<_Base_ptr>(__position._M_node),
2491                                  this->_M_impl._M_header));
2492       _M_drop_node(__y);
2493       --_M_impl._M_node_count;
2494     }
2495
2496   template<typename _Key, typename _Val, typename _KeyOfValue,
2497            typename _Compare, typename _Alloc>
2498     void
2499     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2500     _M_erase_aux(const_iterator __first, const_iterator __last)
2501     {
2502       if (__first == begin() && __last == end())
2503         clear();
2504       else
2505         while (__first != __last)
2506           _M_erase_aux(__first++);
2507     }
2508
2509   template<typename _Key, typename _Val, typename _KeyOfValue,
2510            typename _Compare, typename _Alloc>
2511     typename _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::size_type
2512     _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
2513     erase(const _Key& __x)
2514     {
2515       pair<iterator, iterator> __p = equal_range(__x);
2516       const size_type __old_size = size();
2517       _M_erase_aux(__p.first, __p.second);
2518       return __old_size - size();
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