aboutsummaryrefslogblamecommitdiffstats
path: root/contrib/libs/cxxsupp/libcxx/include/__tree
blob: f3f2e8d15f5d2cb663012bbbf7e5391feb702d0e (plain) (tree)
1
2
3
4
5
6
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729

                                                                                

                                                                                






















                                                                                





                                                                          






















































































































































































































































































































































































































































































































                                                                                       
                                                                            

























                                                                                                
                                                                  



































































































































































































































                                                                                         








                                                                              






























































































































































                                                                                                 
                                   

                                                                                          
                                      




















































































































































                                                                                              
                                                          






























































































































































































                                                                                                        


                                                    














































































































































































































































































































































































































































































































































































                                                                                                               
 




































                                                                               
 


































                                                                                  
 












































                                                                               
 













































                                                                                  
             














                                                                        

                                                            









































































































































































                                                                                                               
                                                                                        
 
                        
          
                                

                                               
                                                                  























                                                                 
                         






















                                                                          
                             






























































                                                                                      
                         
















                                                                                       
                         























                                                                                      
                              





                                                            

















































































































































































































































































































                                                                                                                         
                                                                 
















                                                          
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___TREE
#define _LIBCPP___TREE

#include <__config>
#include <__utility/forward.h>
#include <algorithm>
#include <iterator>
#include <limits>
#include <memory>
#include <stdexcept>

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

_LIBCPP_PUSH_MACROS
#include <__undef_macros>


_LIBCPP_BEGIN_NAMESPACE_STD

#if defined(__GNUC__) && !defined(__clang__) // gcc.gnu.org/PR37804
template <class, class, class, class> class _LIBCPP_TEMPLATE_VIS map;
template <class, class, class, class> class _LIBCPP_TEMPLATE_VIS multimap;
template <class, class, class> class _LIBCPP_TEMPLATE_VIS set;
template <class, class, class> class _LIBCPP_TEMPLATE_VIS multiset;
#endif

template <class _Tp, class _Compare, class _Allocator> class __tree;
template <class _Tp, class _NodePtr, class _DiffType>
    class _LIBCPP_TEMPLATE_VIS __tree_iterator;
template <class _Tp, class _ConstNodePtr, class _DiffType>
    class _LIBCPP_TEMPLATE_VIS __tree_const_iterator;

template <class _Pointer> class __tree_end_node;
template <class _VoidPtr> class __tree_node_base;
template <class _Tp, class _VoidPtr> class __tree_node;

template <class _Key, class _Value>
struct __value_type;

template <class _Allocator> class __map_node_destructor;
template <class _TreeIterator> class _LIBCPP_TEMPLATE_VIS __map_iterator;
template <class _TreeIterator> class _LIBCPP_TEMPLATE_VIS __map_const_iterator;

/*

_NodePtr algorithms

The algorithms taking _NodePtr are red black tree algorithms.  Those
algorithms taking a parameter named __root should assume that __root
points to a proper red black tree (unless otherwise specified).

Each algorithm herein assumes that __root->__parent_ points to a non-null
structure which has a member __left_ which points back to __root.  No other
member is read or written to at __root->__parent_.

__root->__parent_ will be referred to below (in comments only) as end_node.
end_node->__left_ is an externably accessible lvalue for __root, and can be
changed by node insertion and removal (without explicit reference to end_node).

All nodes (with the exception of end_node), even the node referred to as
__root, have a non-null __parent_ field.

*/

// Returns:  true if __x is a left child of its parent, else false
// Precondition:  __x != nullptr.
template <class _NodePtr>
inline _LIBCPP_INLINE_VISIBILITY
bool
__tree_is_left_child(_NodePtr __x) _NOEXCEPT
{
    return __x == __x->__parent_->__left_;
}

// Determines if the subtree rooted at __x is a proper red black subtree.  If
//    __x is a proper subtree, returns the black height (null counts as 1).  If
//    __x is an improper subtree, returns 0.
template <class _NodePtr>
unsigned
__tree_sub_invariant(_NodePtr __x)
{
    if (__x == nullptr)
        return 1;
    // parent consistency checked by caller
    // check __x->__left_ consistency
    if (__x->__left_ != nullptr && __x->__left_->__parent_ != __x)
        return 0;
    // check __x->__right_ consistency
    if (__x->__right_ != nullptr && __x->__right_->__parent_ != __x)
        return 0;
    // check __x->__left_ != __x->__right_ unless both are nullptr
    if (__x->__left_ == __x->__right_ && __x->__left_ != nullptr)
        return 0;
    // If this is red, neither child can be red
    if (!__x->__is_black_)
    {
        if (__x->__left_ && !__x->__left_->__is_black_)
            return 0;
        if (__x->__right_ && !__x->__right_->__is_black_)
            return 0;
    }
    unsigned __h = _VSTD::__tree_sub_invariant(__x->__left_);
    if (__h == 0)
        return 0;  // invalid left subtree
    if (__h != _VSTD::__tree_sub_invariant(__x->__right_))
        return 0;  // invalid or different height right subtree
    return __h + __x->__is_black_;  // return black height of this node
}

// Determines if the red black tree rooted at __root is a proper red black tree.
//    __root == nullptr is a proper tree.  Returns true is __root is a proper
//    red black tree, else returns false.
template <class _NodePtr>
bool
__tree_invariant(_NodePtr __root)
{
    if (__root == nullptr)
        return true;
    // check __x->__parent_ consistency
    if (__root->__parent_ == nullptr)
        return false;
    if (!_VSTD::__tree_is_left_child(__root))
        return false;
    // root must be black
    if (!__root->__is_black_)
        return false;
    // do normal node checks
    return _VSTD::__tree_sub_invariant(__root) != 0;
}

// Returns:  pointer to the left-most node under __x.
// Precondition:  __x != nullptr.
template <class _NodePtr>
inline _LIBCPP_INLINE_VISIBILITY
_NodePtr
__tree_min(_NodePtr __x) _NOEXCEPT
{
    while (__x->__left_ != nullptr)
        __x = __x->__left_;
    return __x;
}

// Returns:  pointer to the right-most node under __x.
// Precondition:  __x != nullptr.
template <class _NodePtr>
inline _LIBCPP_INLINE_VISIBILITY
_NodePtr
__tree_max(_NodePtr __x) _NOEXCEPT
{
    while (__x->__right_ != nullptr)
        __x = __x->__right_;
    return __x;
}

// Returns:  pointer to the next in-order node after __x.
// Precondition:  __x != nullptr.
template <class _NodePtr>
_NodePtr
__tree_next(_NodePtr __x) _NOEXCEPT
{
    if (__x->__right_ != nullptr)
        return _VSTD::__tree_min(__x->__right_);
    while (!_VSTD::__tree_is_left_child(__x))
        __x = __x->__parent_unsafe();
    return __x->__parent_unsafe();
}

template <class _EndNodePtr, class _NodePtr>
inline _LIBCPP_INLINE_VISIBILITY
_EndNodePtr
__tree_next_iter(_NodePtr __x) _NOEXCEPT
{
    if (__x->__right_ != nullptr)
        return static_cast<_EndNodePtr>(_VSTD::__tree_min(__x->__right_));
    while (!_VSTD::__tree_is_left_child(__x))
        __x = __x->__parent_unsafe();
    return static_cast<_EndNodePtr>(__x->__parent_);
}

// Returns:  pointer to the previous in-order node before __x.
// Precondition:  __x != nullptr.
// Note: __x may be the end node.
template <class _NodePtr, class _EndNodePtr>
inline _LIBCPP_INLINE_VISIBILITY
_NodePtr
__tree_prev_iter(_EndNodePtr __x) _NOEXCEPT
{
    if (__x->__left_ != nullptr)
        return _VSTD::__tree_max(__x->__left_);
    _NodePtr __xx = static_cast<_NodePtr>(__x);
    while (_VSTD::__tree_is_left_child(__xx))
        __xx = __xx->__parent_unsafe();
    return __xx->__parent_unsafe();
}

// Returns:  pointer to a node which has no children
// Precondition:  __x != nullptr.
template <class _NodePtr>
_NodePtr
__tree_leaf(_NodePtr __x) _NOEXCEPT
{
    while (true)
    {
        if (__x->__left_ != nullptr)
        {
            __x = __x->__left_;
            continue;
        }
        if (__x->__right_ != nullptr)
        {
            __x = __x->__right_;
            continue;
        }
        break;
    }
    return __x;
}

// Effects:  Makes __x->__right_ the subtree root with __x as its left child
//           while preserving in-order order.
// Precondition:  __x->__right_ != nullptr
template <class _NodePtr>
void
__tree_left_rotate(_NodePtr __x) _NOEXCEPT
{
    _NodePtr __y = __x->__right_;
    __x->__right_ = __y->__left_;
    if (__x->__right_ != nullptr)
        __x->__right_->__set_parent(__x);
    __y->__parent_ = __x->__parent_;
    if (_VSTD::__tree_is_left_child(__x))
        __x->__parent_->__left_ = __y;
    else
        __x->__parent_unsafe()->__right_ = __y;
    __y->__left_ = __x;
    __x->__set_parent(__y);
}

// Effects:  Makes __x->__left_ the subtree root with __x as its right child
//           while preserving in-order order.
// Precondition:  __x->__left_ != nullptr
template <class _NodePtr>
void
__tree_right_rotate(_NodePtr __x) _NOEXCEPT
{
    _NodePtr __y = __x->__left_;
    __x->__left_ = __y->__right_;
    if (__x->__left_ != nullptr)
        __x->__left_->__set_parent(__x);
    __y->__parent_ = __x->__parent_;
    if (_VSTD::__tree_is_left_child(__x))
        __x->__parent_->__left_ = __y;
    else
        __x->__parent_unsafe()->__right_ = __y;
    __y->__right_ = __x;
    __x->__set_parent(__y);
}

// Effects:  Rebalances __root after attaching __x to a leaf.
// Precondition:  __root != nulptr && __x != nullptr.
//                __x has no children.
//                __x == __root or == a direct or indirect child of __root.
//                If __x were to be unlinked from __root (setting __root to
//                  nullptr if __root == __x), __tree_invariant(__root) == true.
// Postcondition: __tree_invariant(end_node->__left_) == true.  end_node->__left_
//                may be different than the value passed in as __root.
template <class _NodePtr>
void
__tree_balance_after_insert(_NodePtr __root, _NodePtr __x) _NOEXCEPT
{
    __x->__is_black_ = __x == __root;
    while (__x != __root && !__x->__parent_unsafe()->__is_black_)
    {
        // __x->__parent_ != __root because __x->__parent_->__is_black == false
        if (_VSTD::__tree_is_left_child(__x->__parent_unsafe()))
        {
            _NodePtr __y = __x->__parent_unsafe()->__parent_unsafe()->__right_;
            if (__y != nullptr && !__y->__is_black_)
            {
                __x = __x->__parent_unsafe();
                __x->__is_black_ = true;
                __x = __x->__parent_unsafe();
                __x->__is_black_ = __x == __root;
                __y->__is_black_ = true;
            }
            else
            {
                if (!_VSTD::__tree_is_left_child(__x))
                {
                    __x = __x->__parent_unsafe();
                    _VSTD::__tree_left_rotate(__x);
                }
                __x = __x->__parent_unsafe();
                __x->__is_black_ = true;
                __x = __x->__parent_unsafe();
                __x->__is_black_ = false;
                _VSTD::__tree_right_rotate(__x);
                break;
            }
        }
        else
        {
            _NodePtr __y = __x->__parent_unsafe()->__parent_->__left_;
            if (__y != nullptr && !__y->__is_black_)
            {
                __x = __x->__parent_unsafe();
                __x->__is_black_ = true;
                __x = __x->__parent_unsafe();
                __x->__is_black_ = __x == __root;
                __y->__is_black_ = true;
            }
            else
            {
                if (_VSTD::__tree_is_left_child(__x))
                {
                    __x = __x->__parent_unsafe();
                    _VSTD::__tree_right_rotate(__x);
                }
                __x = __x->__parent_unsafe();
                __x->__is_black_ = true;
                __x = __x->__parent_unsafe();
                __x->__is_black_ = false;
                _VSTD::__tree_left_rotate(__x);
                break;
            }
        }
    }
}

// Precondition:  __root != nullptr && __z != nullptr.
//                __tree_invariant(__root) == true.
//                __z == __root or == a direct or indirect child of __root.
// Effects:  unlinks __z from the tree rooted at __root, rebalancing as needed.
// Postcondition: __tree_invariant(end_node->__left_) == true && end_node->__left_
//                nor any of its children refer to __z.  end_node->__left_
//                may be different than the value passed in as __root.
template <class _NodePtr>
void
__tree_remove(_NodePtr __root, _NodePtr __z) _NOEXCEPT
{
    // __z will be removed from the tree.  Client still needs to destruct/deallocate it
    // __y is either __z, or if __z has two children, __tree_next(__z).
    // __y will have at most one child.
    // __y will be the initial hole in the tree (make the hole at a leaf)
    _NodePtr __y = (__z->__left_ == nullptr || __z->__right_ == nullptr) ?
                    __z : _VSTD::__tree_next(__z);
    // __x is __y's possibly null single child
    _NodePtr __x = __y->__left_ != nullptr ? __y->__left_ : __y->__right_;
    // __w is __x's possibly null uncle (will become __x's sibling)
    _NodePtr __w = nullptr;
    // link __x to __y's parent, and find __w
    if (__x != nullptr)
        __x->__parent_ = __y->__parent_;
    if (_VSTD::__tree_is_left_child(__y))
    {
        __y->__parent_->__left_ = __x;
        if (__y != __root)
            __w = __y->__parent_unsafe()->__right_;
        else
            __root = __x;  // __w == nullptr
    }
    else
    {
        __y->__parent_unsafe()->__right_ = __x;
        // __y can't be root if it is a right child
        __w = __y->__parent_->__left_;
    }
    bool __removed_black = __y->__is_black_;
    // If we didn't remove __z, do so now by splicing in __y for __z,
    //    but copy __z's color.  This does not impact __x or __w.
    if (__y != __z)
    {
        // __z->__left_ != nulptr but __z->__right_ might == __x == nullptr
        __y->__parent_ = __z->__parent_;
        if (_VSTD::__tree_is_left_child(__z))
            __y->__parent_->__left_ = __y;
        else
            __y->__parent_unsafe()->__right_ = __y;
        __y->__left_ = __z->__left_;
        __y->__left_->__set_parent(__y);
        __y->__right_ = __z->__right_;
        if (__y->__right_ != nullptr)
            __y->__right_->__set_parent(__y);
        __y->__is_black_ = __z->__is_black_;
        if (__root == __z)
            __root = __y;
    }
    // There is no need to rebalance if we removed a red, or if we removed
    //     the last node.
    if (__removed_black && __root != nullptr)
    {
        // Rebalance:
        // __x has an implicit black color (transferred from the removed __y)
        //    associated with it, no matter what its color is.
        // If __x is __root (in which case it can't be null), it is supposed
        //    to be black anyway, and if it is doubly black, then the double
        //    can just be ignored.
        // If __x is red (in which case it can't be null), then it can absorb
        //    the implicit black just by setting its color to black.
        // Since __y was black and only had one child (which __x points to), __x
        //   is either red with no children, else null, otherwise __y would have
        //   different black heights under left and right pointers.
        // if (__x == __root || __x != nullptr && !__x->__is_black_)
        if (__x != nullptr)
            __x->__is_black_ = true;
        else
        {
            //  Else __x isn't root, and is "doubly black", even though it may
            //     be null.  __w can not be null here, else the parent would
            //     see a black height >= 2 on the __x side and a black height
            //     of 1 on the __w side (__w must be a non-null black or a red
            //     with a non-null black child).
            while (true)
            {
                if (!_VSTD::__tree_is_left_child(__w))  // if x is left child
                {
                    if (!__w->__is_black_)
                    {
                        __w->__is_black_ = true;
                        __w->__parent_unsafe()->__is_black_ = false;
                        _VSTD::__tree_left_rotate(__w->__parent_unsafe());
                        // __x is still valid
                        // reset __root only if necessary
                        if (__root == __w->__left_)
                            __root = __w;
                        // reset sibling, and it still can't be null
                        __w = __w->__left_->__right_;
                    }
                    // __w->__is_black_ is now true, __w may have null children
                    if ((__w->__left_  == nullptr || __w->__left_->__is_black_) &&
                        (__w->__right_ == nullptr || __w->__right_->__is_black_))
                    {
                        __w->__is_black_ = false;
                        __x = __w->__parent_unsafe();
                        // __x can no longer be null
                        if (__x == __root || !__x->__is_black_)
                        {
                            __x->__is_black_ = true;
                            break;
                        }
                        // reset sibling, and it still can't be null
                        __w = _VSTD::__tree_is_left_child(__x) ?
                                    __x->__parent_unsafe()->__right_ :
                                    __x->__parent_->__left_;
                        // continue;
                    }
                    else  // __w has a red child
                    {
                        if (__w->__right_ == nullptr || __w->__right_->__is_black_)
                        {
                            // __w left child is non-null and red
                            __w->__left_->__is_black_ = true;
                            __w->__is_black_ = false;
                            _VSTD::__tree_right_rotate(__w);
                            // __w is known not to be root, so root hasn't changed
                            // reset sibling, and it still can't be null
                            __w = __w->__parent_unsafe();
                        }
                        // __w has a right red child, left child may be null
                        __w->__is_black_ = __w->__parent_unsafe()->__is_black_;
                        __w->__parent_unsafe()->__is_black_ = true;
                        __w->__right_->__is_black_ = true;
                        _VSTD::__tree_left_rotate(__w->__parent_unsafe());
                        break;
                    }
                }
                else
                {
                    if (!__w->__is_black_)
                    {
                        __w->__is_black_ = true;
                        __w->__parent_unsafe()->__is_black_ = false;
                        _VSTD::__tree_right_rotate(__w->__parent_unsafe());
                        // __x is still valid
                        // reset __root only if necessary
                        if (__root == __w->__right_)
                            __root = __w;
                        // reset sibling, and it still can't be null
                        __w = __w->__right_->__left_;
                    }
                    // __w->__is_black_ is now true, __w may have null children
                    if ((__w->__left_  == nullptr || __w->__left_->__is_black_) &&
                        (__w->__right_ == nullptr || __w->__right_->__is_black_))
                    {
                        __w->__is_black_ = false;
                        __x = __w->__parent_unsafe();
                        // __x can no longer be null
                        if (!__x->__is_black_ || __x == __root)
                        {
                            __x->__is_black_ = true;
                            break;
                        }
                        // reset sibling, and it still can't be null
                        __w = _VSTD::__tree_is_left_child(__x) ?
                                    __x->__parent_unsafe()->__right_ :
                                    __x->__parent_->__left_;
                        // continue;
                    }
                    else  // __w has a red child
                    {
                        if (__w->__left_ == nullptr || __w->__left_->__is_black_)
                        {
                            // __w right child is non-null and red
                            __w->__right_->__is_black_ = true;
                            __w->__is_black_ = false;
                            _VSTD::__tree_left_rotate(__w);
                            // __w is known not to be root, so root hasn't changed
                            // reset sibling, and it still can't be null
                            __w = __w->__parent_unsafe();
                        }
                        // __w has a left red child, right child may be null
                        __w->__is_black_ = __w->__parent_unsafe()->__is_black_;
                        __w->__parent_unsafe()->__is_black_ = true;
                        __w->__left_->__is_black_ = true;
                        _VSTD::__tree_right_rotate(__w->__parent_unsafe());
                        break;
                    }
                }
            }
        }
    }
}

// node traits


template <class _Tp>
struct __is_tree_value_type_imp : false_type {};

template <class _Key, class _Value>
struct __is_tree_value_type_imp<__value_type<_Key, _Value> > : true_type {};

template <class ..._Args>
struct __is_tree_value_type : false_type {};

template <class _One>
struct __is_tree_value_type<_One> : __is_tree_value_type_imp<typename __uncvref<_One>::type> {};

template <class _Tp>
struct __tree_key_value_types {
  typedef _Tp key_type;
  typedef _Tp __node_value_type;
  typedef _Tp __container_value_type;
  static const bool __is_map = false;

  _LIBCPP_INLINE_VISIBILITY
  static key_type const& __get_key(_Tp const& __v) {
    return __v;
  }
  _LIBCPP_INLINE_VISIBILITY
  static __container_value_type const& __get_value(__node_value_type const& __v) {
    return __v;
  }
  _LIBCPP_INLINE_VISIBILITY
  static __container_value_type* __get_ptr(__node_value_type& __n) {
    return _VSTD::addressof(__n);
  }
  _LIBCPP_INLINE_VISIBILITY
  static __container_value_type&& __move(__node_value_type& __v) {
    return _VSTD::move(__v);
  }
};

template <class _Key, class _Tp>
struct __tree_key_value_types<__value_type<_Key, _Tp> > {
  typedef _Key                                         key_type;
  typedef _Tp                                          mapped_type;
  typedef __value_type<_Key, _Tp>                      __node_value_type;
  typedef pair<const _Key, _Tp>                        __container_value_type;
  typedef __container_value_type                       __map_value_type;
  static const bool __is_map = true;

  _LIBCPP_INLINE_VISIBILITY
  static key_type const&
  __get_key(__node_value_type const& __t) {
    return __t.__get_value().first;
  }

  template <class _Up>
  _LIBCPP_INLINE_VISIBILITY
  static typename enable_if<__is_same_uncvref<_Up, __container_value_type>::value,
      key_type const&>::type
  __get_key(_Up& __t) {
    return __t.first;
  }

  _LIBCPP_INLINE_VISIBILITY
  static __container_value_type const&
  __get_value(__node_value_type const& __t) {
    return __t.__get_value();
  }

  template <class _Up>
  _LIBCPP_INLINE_VISIBILITY
  static typename enable_if<__is_same_uncvref<_Up, __container_value_type>::value,
      __container_value_type const&>::type
  __get_value(_Up& __t) {
    return __t;
  }

  _LIBCPP_INLINE_VISIBILITY
  static __container_value_type* __get_ptr(__node_value_type& __n) {
    return _VSTD::addressof(__n.__get_value());
  }

  _LIBCPP_INLINE_VISIBILITY
  static pair<key_type&&, mapped_type&&> __move(__node_value_type& __v) {
    return __v.__move();
  }
};

template <class _VoidPtr>
struct __tree_node_base_types {
  typedef _VoidPtr                                               __void_pointer;

  typedef __tree_node_base<__void_pointer>                      __node_base_type;
  typedef typename __rebind_pointer<_VoidPtr, __node_base_type>::type
                                                             __node_base_pointer;

  typedef __tree_end_node<__node_base_pointer>                  __end_node_type;
  typedef typename __rebind_pointer<_VoidPtr, __end_node_type>::type
                                                             __end_node_pointer;
#if defined(_LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB)
  typedef __end_node_pointer __parent_pointer;
#else
  typedef typename conditional<
      is_pointer<__end_node_pointer>::value,
        __end_node_pointer,
        __node_base_pointer>::type __parent_pointer;
#endif

private:
  static_assert((is_same<typename pointer_traits<_VoidPtr>::element_type, void>::value),
                  "_VoidPtr does not point to unqualified void type");
};

template <class _Tp, class _AllocPtr, class _KVTypes = __tree_key_value_types<_Tp>,
         bool = _KVTypes::__is_map>
struct __tree_map_pointer_types {};

template <class _Tp, class _AllocPtr, class _KVTypes>
struct __tree_map_pointer_types<_Tp, _AllocPtr, _KVTypes, true> {
  typedef typename _KVTypes::__map_value_type   _Mv;
  typedef typename __rebind_pointer<_AllocPtr, _Mv>::type
                                                       __map_value_type_pointer;
  typedef typename __rebind_pointer<_AllocPtr, const _Mv>::type
                                                 __const_map_value_type_pointer;
};

template <class _NodePtr, class _NodeT = typename pointer_traits<_NodePtr>::element_type>
struct __tree_node_types;

template <class _NodePtr, class _Tp, class _VoidPtr>
struct __tree_node_types<_NodePtr, __tree_node<_Tp, _VoidPtr> >
    : public __tree_node_base_types<_VoidPtr>,
             __tree_key_value_types<_Tp>,
             __tree_map_pointer_types<_Tp, _VoidPtr>
{
  typedef __tree_node_base_types<_VoidPtr> __base;
  typedef __tree_key_value_types<_Tp>      __key_base;
  typedef __tree_map_pointer_types<_Tp, _VoidPtr> __map_pointer_base;
public:

  typedef typename pointer_traits<_NodePtr>::element_type       __node_type;
  typedef _NodePtr                                              __node_pointer;

  typedef _Tp                                                 __node_value_type;
  typedef typename __rebind_pointer<_VoidPtr, __node_value_type>::type
                                                      __node_value_type_pointer;
  typedef typename __rebind_pointer<_VoidPtr, const __node_value_type>::type
                                                __const_node_value_type_pointer;
#if defined(_LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB)
  typedef typename __base::__end_node_pointer __iter_pointer;
#else
  typedef typename conditional<
      is_pointer<__node_pointer>::value,
        typename __base::__end_node_pointer,
        __node_pointer>::type __iter_pointer;
#endif
private:
    static_assert(!is_const<__node_type>::value,
                "_NodePtr should never be a pointer to const");
    static_assert((is_same<typename __rebind_pointer<_VoidPtr, __node_type>::type,
                          _NodePtr>::value), "_VoidPtr does not rebind to _NodePtr.");
};

template <class _ValueTp, class _VoidPtr>
struct __make_tree_node_types {
  typedef typename __rebind_pointer<_VoidPtr, __tree_node<_ValueTp, _VoidPtr> >::type
                                                                        _NodePtr;
  typedef __tree_node_types<_NodePtr> type;
};

// node

template <class _Pointer>
class __tree_end_node
{
public:
    typedef _Pointer pointer;
    pointer __left_;

    _LIBCPP_INLINE_VISIBILITY
    __tree_end_node() _NOEXCEPT : __left_() {}
};

template <class _VoidPtr>
class _LIBCPP_STANDALONE_DEBUG __tree_node_base
    : public __tree_node_base_types<_VoidPtr>::__end_node_type
{
    typedef __tree_node_base_types<_VoidPtr> _NodeBaseTypes;

public:
    typedef typename _NodeBaseTypes::__node_base_pointer pointer;
    typedef typename _NodeBaseTypes::__parent_pointer __parent_pointer;

    pointer          __right_;
    __parent_pointer __parent_;
    bool __is_black_;

    _LIBCPP_INLINE_VISIBILITY
    pointer __parent_unsafe() const { return static_cast<pointer>(__parent_);}

    _LIBCPP_INLINE_VISIBILITY
    void __set_parent(pointer __p) {
        __parent_ = static_cast<__parent_pointer>(__p);
    }

private:
  ~__tree_node_base() = delete;
  __tree_node_base(__tree_node_base const&) = delete;
  __tree_node_base& operator=(__tree_node_base const&) = delete;
};

template <class _Tp, class _VoidPtr>
class _LIBCPP_STANDALONE_DEBUG __tree_node
    : public __tree_node_base<_VoidPtr>
{
public:
    typedef _Tp __node_value_type;

    __node_value_type __value_;

private:
  ~__tree_node() = delete;
  __tree_node(__tree_node const&) = delete;
  __tree_node& operator=(__tree_node const&) = delete;
};


template <class _Allocator>
class __tree_node_destructor
{
    typedef _Allocator                                      allocator_type;
    typedef allocator_traits<allocator_type>                __alloc_traits;

public:
    typedef typename __alloc_traits::pointer                pointer;
private:
    typedef __tree_node_types<pointer> _NodeTypes;
    allocator_type& __na_;


public:
    bool __value_constructed;


    __tree_node_destructor(const __tree_node_destructor &) = default;
    __tree_node_destructor& operator=(const __tree_node_destructor&) = delete;

    _LIBCPP_INLINE_VISIBILITY
    explicit __tree_node_destructor(allocator_type& __na, bool __val = false) _NOEXCEPT
        : __na_(__na),
          __value_constructed(__val)
        {}

    _LIBCPP_INLINE_VISIBILITY
    void operator()(pointer __p) _NOEXCEPT
    {
        if (__value_constructed)
            __alloc_traits::destroy(__na_, _NodeTypes::__get_ptr(__p->__value_));
        if (__p)
            __alloc_traits::deallocate(__na_, __p, 1);
    }

    template <class> friend class __map_node_destructor;
};

#if _LIBCPP_STD_VER > 14
template <class _NodeType, class _Alloc>
struct __generic_container_node_destructor;
template <class _Tp, class _VoidPtr, class _Alloc>
struct __generic_container_node_destructor<__tree_node<_Tp, _VoidPtr>, _Alloc>
    : __tree_node_destructor<_Alloc>
{
    using __tree_node_destructor<_Alloc>::__tree_node_destructor;
};
#endif

template <class _Tp, class _NodePtr, class _DiffType>
class _LIBCPP_TEMPLATE_VIS __tree_iterator
{
    typedef __tree_node_types<_NodePtr>                     _NodeTypes;
    typedef _NodePtr                                        __node_pointer;
    typedef typename _NodeTypes::__node_base_pointer        __node_base_pointer;
    typedef typename _NodeTypes::__end_node_pointer         __end_node_pointer;
    typedef typename _NodeTypes::__iter_pointer             __iter_pointer;
    typedef pointer_traits<__node_pointer> __pointer_traits;

    __iter_pointer __ptr_;

public:
    typedef bidirectional_iterator_tag                     iterator_category;
    typedef _Tp                                            value_type;
    typedef _DiffType                                      difference_type;
    typedef value_type&                                    reference;
    typedef typename _NodeTypes::__node_value_type_pointer pointer;

    _LIBCPP_INLINE_VISIBILITY __tree_iterator() _NOEXCEPT
#if _LIBCPP_STD_VER > 11
    : __ptr_(nullptr)
#endif
    {}

    _LIBCPP_INLINE_VISIBILITY reference operator*() const
        {return __get_np()->__value_;}
    _LIBCPP_INLINE_VISIBILITY pointer operator->() const
        {return pointer_traits<pointer>::pointer_to(__get_np()->__value_);}

    _LIBCPP_INLINE_VISIBILITY
    __tree_iterator& operator++() {
      __ptr_ = static_cast<__iter_pointer>(
          _VSTD::__tree_next_iter<__end_node_pointer>(static_cast<__node_base_pointer>(__ptr_)));
      return *this;
    }
    _LIBCPP_INLINE_VISIBILITY
    __tree_iterator operator++(int)
        {__tree_iterator __t(*this); ++(*this); return __t;}

    _LIBCPP_INLINE_VISIBILITY
    __tree_iterator& operator--() {
      __ptr_ = static_cast<__iter_pointer>(_VSTD::__tree_prev_iter<__node_base_pointer>(
          static_cast<__end_node_pointer>(__ptr_)));
      return *this;
    }
    _LIBCPP_INLINE_VISIBILITY
    __tree_iterator operator--(int)
        {__tree_iterator __t(*this); --(*this); return __t;}

    friend _LIBCPP_INLINE_VISIBILITY
        bool operator==(const __tree_iterator& __x, const __tree_iterator& __y)
        {return __x.__ptr_ == __y.__ptr_;}
    friend _LIBCPP_INLINE_VISIBILITY
        bool operator!=(const __tree_iterator& __x, const __tree_iterator& __y)
        {return !(__x == __y);}

private:
    _LIBCPP_INLINE_VISIBILITY
    explicit __tree_iterator(__node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    explicit __tree_iterator(__end_node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    __node_pointer __get_np() const { return static_cast<__node_pointer>(__ptr_); }
    template <class, class, class> friend class __tree;
    template <class, class, class> friend class _LIBCPP_TEMPLATE_VIS __tree_const_iterator;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __map_iterator;
    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS map;
    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS multimap;
    template <class, class, class> friend class _LIBCPP_TEMPLATE_VIS set;
    template <class, class, class> friend class _LIBCPP_TEMPLATE_VIS multiset;
};

template <class _Tp, class _NodePtr, class _DiffType>
class _LIBCPP_TEMPLATE_VIS __tree_const_iterator
{
    typedef __tree_node_types<_NodePtr>                     _NodeTypes;
    typedef typename _NodeTypes::__node_pointer             __node_pointer;
    typedef typename _NodeTypes::__node_base_pointer        __node_base_pointer;
    typedef typename _NodeTypes::__end_node_pointer         __end_node_pointer;
    typedef typename _NodeTypes::__iter_pointer             __iter_pointer;
    typedef pointer_traits<__node_pointer> __pointer_traits;

    __iter_pointer __ptr_;

public:
    typedef bidirectional_iterator_tag                           iterator_category;
    typedef _Tp                                                  value_type;
    typedef _DiffType                                            difference_type;
    typedef const value_type&                                    reference;
    typedef typename _NodeTypes::__const_node_value_type_pointer pointer;

    _LIBCPP_INLINE_VISIBILITY __tree_const_iterator() _NOEXCEPT
#if _LIBCPP_STD_VER > 11
    : __ptr_(nullptr)
#endif
    {}

private:
    typedef __tree_iterator<value_type, __node_pointer, difference_type>
                                                           __non_const_iterator;
public:
    _LIBCPP_INLINE_VISIBILITY
    __tree_const_iterator(__non_const_iterator __p) _NOEXCEPT
        : __ptr_(__p.__ptr_) {}

    _LIBCPP_INLINE_VISIBILITY reference operator*() const
        {return __get_np()->__value_;}
    _LIBCPP_INLINE_VISIBILITY pointer operator->() const
        {return pointer_traits<pointer>::pointer_to(__get_np()->__value_);}

    _LIBCPP_INLINE_VISIBILITY
    __tree_const_iterator& operator++() {
      __ptr_ = static_cast<__iter_pointer>(
          _VSTD::__tree_next_iter<__end_node_pointer>(static_cast<__node_base_pointer>(__ptr_)));
      return *this;
    }

    _LIBCPP_INLINE_VISIBILITY
    __tree_const_iterator operator++(int)
        {__tree_const_iterator __t(*this); ++(*this); return __t;}

    _LIBCPP_INLINE_VISIBILITY
    __tree_const_iterator& operator--() {
      __ptr_ = static_cast<__iter_pointer>(_VSTD::__tree_prev_iter<__node_base_pointer>(
          static_cast<__end_node_pointer>(__ptr_)));
      return *this;
    }

    _LIBCPP_INLINE_VISIBILITY
    __tree_const_iterator operator--(int)
        {__tree_const_iterator __t(*this); --(*this); return __t;}

    friend _LIBCPP_INLINE_VISIBILITY
        bool operator==(const __tree_const_iterator& __x, const __tree_const_iterator& __y)
        {return __x.__ptr_ == __y.__ptr_;}
    friend _LIBCPP_INLINE_VISIBILITY
        bool operator!=(const __tree_const_iterator& __x, const __tree_const_iterator& __y)
        {return !(__x == __y);}

private:
    _LIBCPP_INLINE_VISIBILITY
    explicit __tree_const_iterator(__node_pointer __p) _NOEXCEPT
        : __ptr_(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    explicit __tree_const_iterator(__end_node_pointer __p) _NOEXCEPT
        : __ptr_(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    __node_pointer __get_np() const { return static_cast<__node_pointer>(__ptr_); }

    template <class, class, class> friend class __tree;
    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS map;
    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS multimap;
    template <class, class, class> friend class _LIBCPP_TEMPLATE_VIS set;
    template <class, class, class> friend class _LIBCPP_TEMPLATE_VIS multiset;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __map_const_iterator;

};

template<class _Tp, class _Compare>
#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_DIAGNOSE_WARNING(!__invokable<_Compare const&, _Tp const&, _Tp const&>::value,
        "the specified comparator type does not provide a viable const call operator")
#endif
int __diagnose_non_const_comparator();

template <class _Tp, class _Compare, class _Allocator>
class __tree
{
public:
    typedef _Tp                                      value_type;
    typedef _Compare                                 value_compare;
    typedef _Allocator                               allocator_type;

private:
    typedef allocator_traits<allocator_type>         __alloc_traits;
    typedef typename __make_tree_node_types<value_type,
        typename __alloc_traits::void_pointer>::type
                                                    _NodeTypes;
    typedef typename _NodeTypes::key_type           key_type;
public:
    typedef typename _NodeTypes::__node_value_type      __node_value_type;
    typedef typename _NodeTypes::__container_value_type __container_value_type;

    typedef typename __alloc_traits::pointer         pointer;
    typedef typename __alloc_traits::const_pointer   const_pointer;
    typedef typename __alloc_traits::size_type       size_type;
    typedef typename __alloc_traits::difference_type difference_type;

public:
    typedef typename _NodeTypes::__void_pointer        __void_pointer;

    typedef typename _NodeTypes::__node_type           __node;
    typedef typename _NodeTypes::__node_pointer        __node_pointer;

    typedef typename _NodeTypes::__node_base_type      __node_base;
    typedef typename _NodeTypes::__node_base_pointer   __node_base_pointer;

    typedef typename _NodeTypes::__end_node_type       __end_node_t;
    typedef typename _NodeTypes::__end_node_pointer    __end_node_ptr;

    typedef typename _NodeTypes::__parent_pointer      __parent_pointer;
    typedef typename _NodeTypes::__iter_pointer        __iter_pointer;

    typedef typename __rebind_alloc_helper<__alloc_traits, __node>::type __node_allocator;
    typedef allocator_traits<__node_allocator>         __node_traits;

private:
    // check for sane allocator pointer rebinding semantics. Rebinding the
    // allocator for a new pointer type should be exactly the same as rebinding
    // the pointer using 'pointer_traits'.
    static_assert((is_same<__node_pointer, typename __node_traits::pointer>::value),
                  "Allocator does not rebind pointers in a sane manner.");
    typedef typename __rebind_alloc_helper<__node_traits, __node_base>::type
        __node_base_allocator;
    typedef allocator_traits<__node_base_allocator> __node_base_traits;
    static_assert((is_same<__node_base_pointer, typename __node_base_traits::pointer>::value),
                 "Allocator does not rebind pointers in a sane manner.");

private:
    __iter_pointer                                     __begin_node_;
    __compressed_pair<__end_node_t, __node_allocator>  __pair1_;
    __compressed_pair<size_type, value_compare>        __pair3_;

public:
    _LIBCPP_INLINE_VISIBILITY
    __iter_pointer __end_node() _NOEXCEPT
    {
        return static_cast<__iter_pointer>(
                pointer_traits<__end_node_ptr>::pointer_to(__pair1_.first())
        );
    }
    _LIBCPP_INLINE_VISIBILITY
    __iter_pointer __end_node() const _NOEXCEPT
    {
        return static_cast<__iter_pointer>(
            pointer_traits<__end_node_ptr>::pointer_to(
                const_cast<__end_node_t&>(__pair1_.first())
            )
        );
    }
    _LIBCPP_INLINE_VISIBILITY
          __node_allocator& __node_alloc() _NOEXCEPT {return __pair1_.second();}
private:
    _LIBCPP_INLINE_VISIBILITY
    const __node_allocator& __node_alloc() const _NOEXCEPT
        {return __pair1_.second();}
    _LIBCPP_INLINE_VISIBILITY
          __iter_pointer& __begin_node() _NOEXCEPT {return __begin_node_;}
    _LIBCPP_INLINE_VISIBILITY
    const __iter_pointer& __begin_node() const _NOEXCEPT {return __begin_node_;}
public:
    _LIBCPP_INLINE_VISIBILITY
    allocator_type __alloc() const _NOEXCEPT
        {return allocator_type(__node_alloc());}
private:
    _LIBCPP_INLINE_VISIBILITY
          size_type& size() _NOEXCEPT {return __pair3_.first();}
public:
    _LIBCPP_INLINE_VISIBILITY
    const size_type& size() const _NOEXCEPT {return __pair3_.first();}
    _LIBCPP_INLINE_VISIBILITY
          value_compare& value_comp() _NOEXCEPT {return __pair3_.second();}
    _LIBCPP_INLINE_VISIBILITY
    const value_compare& value_comp() const _NOEXCEPT
        {return __pair3_.second();}
public:

    _LIBCPP_INLINE_VISIBILITY
    __node_pointer __root() const _NOEXCEPT
        {return static_cast<__node_pointer>(__end_node()->__left_);}

    __node_base_pointer* __root_ptr() const _NOEXCEPT {
        return _VSTD::addressof(__end_node()->__left_);
    }

    typedef __tree_iterator<value_type, __node_pointer, difference_type>             iterator;
    typedef __tree_const_iterator<value_type, __node_pointer, difference_type> const_iterator;

    explicit __tree(const value_compare& __comp)
        _NOEXCEPT_(
            is_nothrow_default_constructible<__node_allocator>::value &&
            is_nothrow_copy_constructible<value_compare>::value);
    explicit __tree(const allocator_type& __a);
    __tree(const value_compare& __comp, const allocator_type& __a);
    __tree(const __tree& __t);
    __tree& operator=(const __tree& __t);
    template <class _ForwardIterator>
        void __assign_unique(_ForwardIterator __first, _ForwardIterator __last);
    template <class _InputIterator>
        void __assign_multi(_InputIterator __first, _InputIterator __last);
    __tree(__tree&& __t)
        _NOEXCEPT_(
            is_nothrow_move_constructible<__node_allocator>::value &&
            is_nothrow_move_constructible<value_compare>::value);
    __tree(__tree&& __t, const allocator_type& __a);
    __tree& operator=(__tree&& __t)
        _NOEXCEPT_(
            __node_traits::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<value_compare>::value &&
            is_nothrow_move_assignable<__node_allocator>::value);
    ~__tree();

    _LIBCPP_INLINE_VISIBILITY
          iterator begin()  _NOEXCEPT {return       iterator(__begin_node());}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator begin() const _NOEXCEPT {return const_iterator(__begin_node());}
    _LIBCPP_INLINE_VISIBILITY
          iterator end() _NOEXCEPT {return       iterator(__end_node());}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator end() const _NOEXCEPT {return const_iterator(__end_node());}

    _LIBCPP_INLINE_VISIBILITY
    size_type max_size() const _NOEXCEPT
        {return _VSTD::min<size_type>(
                __node_traits::max_size(__node_alloc()),
                numeric_limits<difference_type >::max());}

    void clear() _NOEXCEPT;

    void swap(__tree& __t)
#if _LIBCPP_STD_VER <= 11
        _NOEXCEPT_(
            __is_nothrow_swappable<value_compare>::value
            && (!__node_traits::propagate_on_container_swap::value ||
                 __is_nothrow_swappable<__node_allocator>::value)
            );
#else
        _NOEXCEPT_(__is_nothrow_swappable<value_compare>::value);
#endif

    template <class _Key, class ..._Args>
    pair<iterator, bool>
    __emplace_unique_key_args(_Key const&, _Args&&... __args);
    template <class _Key, class ..._Args>
    pair<iterator, bool>
    __emplace_hint_unique_key_args(const_iterator, _Key const&, _Args&&...);

    template <class... _Args>
    pair<iterator, bool> __emplace_unique_impl(_Args&&... __args);

    template <class... _Args>
    iterator __emplace_hint_unique_impl(const_iterator __p, _Args&&... __args);

    template <class... _Args>
    iterator __emplace_multi(_Args&&... __args);

    template <class... _Args>
    iterator __emplace_hint_multi(const_iterator __p, _Args&&... __args);

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __emplace_unique(_Pp&& __x) {
        return __emplace_unique_extract_key(_VSTD::forward<_Pp>(__x),
                                            __can_extract_key<_Pp, key_type>());
    }

    template <class _First, class _Second>
    _LIBCPP_INLINE_VISIBILITY
    typename enable_if<
        __can_extract_map_key<_First, key_type, __container_value_type>::value,
        pair<iterator, bool>
    >::type __emplace_unique(_First&& __f, _Second&& __s) {
        return __emplace_unique_key_args(__f, _VSTD::forward<_First>(__f),
                                              _VSTD::forward<_Second>(__s));
    }

    template <class... _Args>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __emplace_unique(_Args&&... __args) {
        return __emplace_unique_impl(_VSTD::forward<_Args>(__args)...);
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool>
    __emplace_unique_extract_key(_Pp&& __x, __extract_key_fail_tag) {
      return __emplace_unique_impl(_VSTD::forward<_Pp>(__x));
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool>
    __emplace_unique_extract_key(_Pp&& __x, __extract_key_self_tag) {
      return __emplace_unique_key_args(__x, _VSTD::forward<_Pp>(__x));
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool>
    __emplace_unique_extract_key(_Pp&& __x, __extract_key_first_tag) {
      return __emplace_unique_key_args(__x.first, _VSTD::forward<_Pp>(__x));
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    iterator __emplace_hint_unique(const_iterator __p, _Pp&& __x) {
        return __emplace_hint_unique_extract_key(__p, _VSTD::forward<_Pp>(__x),
                                            __can_extract_key<_Pp, key_type>());
    }

    template <class _First, class _Second>
    _LIBCPP_INLINE_VISIBILITY
    typename enable_if<
        __can_extract_map_key<_First, key_type, __container_value_type>::value,
        iterator
    >::type __emplace_hint_unique(const_iterator __p, _First&& __f, _Second&& __s) {
        return __emplace_hint_unique_key_args(__p, __f,
                                              _VSTD::forward<_First>(__f),
                                              _VSTD::forward<_Second>(__s)).first;
    }

    template <class... _Args>
    _LIBCPP_INLINE_VISIBILITY
    iterator __emplace_hint_unique(const_iterator __p, _Args&&... __args) {
        return __emplace_hint_unique_impl(__p, _VSTD::forward<_Args>(__args)...);
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    iterator
    __emplace_hint_unique_extract_key(const_iterator __p, _Pp&& __x, __extract_key_fail_tag) {
      return __emplace_hint_unique_impl(__p, _VSTD::forward<_Pp>(__x));
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    iterator
    __emplace_hint_unique_extract_key(const_iterator __p, _Pp&& __x, __extract_key_self_tag) {
      return __emplace_hint_unique_key_args(__p, __x, _VSTD::forward<_Pp>(__x)).first;
    }

    template <class _Pp>
    _LIBCPP_INLINE_VISIBILITY
    iterator
    __emplace_hint_unique_extract_key(const_iterator __p, _Pp&& __x, __extract_key_first_tag) {
      return __emplace_hint_unique_key_args(__p, __x.first, _VSTD::forward<_Pp>(__x)).first;
    }

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __insert_unique(const __container_value_type& __v) {
        return __emplace_unique_key_args(_NodeTypes::__get_key(__v), __v);
    }

    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_unique(const_iterator __p, const __container_value_type& __v) {
        return __emplace_hint_unique_key_args(__p, _NodeTypes::__get_key(__v), __v).first;
    }

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __insert_unique(__container_value_type&& __v) {
        return __emplace_unique_key_args(_NodeTypes::__get_key(__v), _VSTD::move(__v));
    }

    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_unique(const_iterator __p, __container_value_type&& __v) {
        return __emplace_hint_unique_key_args(__p, _NodeTypes::__get_key(__v), _VSTD::move(__v)).first;
    }

    template <class _Vp, class = typename enable_if<
            !is_same<typename __unconstref<_Vp>::type,
                     __container_value_type
            >::value
        >::type>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __insert_unique(_Vp&& __v) {
        return __emplace_unique(_VSTD::forward<_Vp>(__v));
    }

    template <class _Vp, class = typename enable_if<
            !is_same<typename __unconstref<_Vp>::type,
                     __container_value_type
            >::value
        >::type>
    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_unique(const_iterator __p, _Vp&& __v) {
        return __emplace_hint_unique(__p, _VSTD::forward<_Vp>(__v));
    }

    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_multi(__container_value_type&& __v) {
        return __emplace_multi(_VSTD::move(__v));
    }

    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_multi(const_iterator __p, __container_value_type&& __v) {
        return __emplace_hint_multi(__p, _VSTD::move(__v));
    }

    template <class _Vp>
    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_multi(_Vp&& __v) {
        return __emplace_multi(_VSTD::forward<_Vp>(__v));
    }

    template <class _Vp>
    _LIBCPP_INLINE_VISIBILITY
    iterator __insert_multi(const_iterator __p, _Vp&& __v) {
        return __emplace_hint_multi(__p, _VSTD::forward<_Vp>(__v));
    }

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> __node_assign_unique(const __container_value_type& __v, __node_pointer __dest);

    _LIBCPP_INLINE_VISIBILITY
    iterator __node_insert_multi(__node_pointer __nd);
    _LIBCPP_INLINE_VISIBILITY
    iterator __node_insert_multi(const_iterator __p, __node_pointer __nd);


    _LIBCPP_INLINE_VISIBILITY iterator
    __remove_node_pointer(__node_pointer) _NOEXCEPT;

#if _LIBCPP_STD_VER > 14
    template <class _NodeHandle, class _InsertReturnType>
    _LIBCPP_INLINE_VISIBILITY
    _InsertReturnType __node_handle_insert_unique(_NodeHandle&&);
    template <class _NodeHandle>
    _LIBCPP_INLINE_VISIBILITY
    iterator __node_handle_insert_unique(const_iterator, _NodeHandle&&);
    template <class _Tree>
    _LIBCPP_INLINE_VISIBILITY
    void __node_handle_merge_unique(_Tree& __source);

    template <class _NodeHandle>
    _LIBCPP_INLINE_VISIBILITY
    iterator __node_handle_insert_multi(_NodeHandle&&);
    template <class _NodeHandle>
    _LIBCPP_INLINE_VISIBILITY
    iterator __node_handle_insert_multi(const_iterator, _NodeHandle&&);
    template <class _Tree>
    _LIBCPP_INLINE_VISIBILITY
    void __node_handle_merge_multi(_Tree& __source);


    template <class _NodeHandle>
    _LIBCPP_INLINE_VISIBILITY
    _NodeHandle __node_handle_extract(key_type const&);
    template <class _NodeHandle>
    _LIBCPP_INLINE_VISIBILITY
    _NodeHandle __node_handle_extract(const_iterator);
#endif

    iterator erase(const_iterator __p);
    iterator erase(const_iterator __f, const_iterator __l);
    template <class _Key>
        size_type __erase_unique(const _Key& __k);
    template <class _Key>
        size_type __erase_multi(const _Key& __k);

    void __insert_node_at(__parent_pointer     __parent,
                          __node_base_pointer& __child,
                          __node_base_pointer __new_node) _NOEXCEPT;

    template <class _Key>
        iterator find(const _Key& __v);
    template <class _Key>
        const_iterator find(const _Key& __v) const;

    template <class _Key>
        size_type __count_unique(const _Key& __k) const;
    template <class _Key>
        size_type __count_multi(const _Key& __k) const;

    template <class _Key>
        _LIBCPP_INLINE_VISIBILITY
        iterator lower_bound(const _Key& __v)
            {return __lower_bound(__v, __root(), __end_node());}
    template <class _Key>
        iterator __lower_bound(const _Key& __v,
                               __node_pointer __root,
                               __iter_pointer __result);
    template <class _Key>
        _LIBCPP_INLINE_VISIBILITY
        const_iterator lower_bound(const _Key& __v) const
            {return __lower_bound(__v, __root(), __end_node());}
    template <class _Key>
        const_iterator __lower_bound(const _Key& __v,
                                     __node_pointer __root,
                                     __iter_pointer __result) const;
    template <class _Key>
        _LIBCPP_INLINE_VISIBILITY
        iterator upper_bound(const _Key& __v)
            {return __upper_bound(__v, __root(), __end_node());}
    template <class _Key>
        iterator __upper_bound(const _Key& __v,
                               __node_pointer __root,
                               __iter_pointer __result);
    template <class _Key>
        _LIBCPP_INLINE_VISIBILITY
        const_iterator upper_bound(const _Key& __v) const
            {return __upper_bound(__v, __root(), __end_node());}
    template <class _Key>
        const_iterator __upper_bound(const _Key& __v,
                                     __node_pointer __root,
                                     __iter_pointer __result) const;
    template <class _Key>
        pair<iterator, iterator>
        __equal_range_unique(const _Key& __k);
    template <class _Key>
        pair<const_iterator, const_iterator>
        __equal_range_unique(const _Key& __k) const;

    template <class _Key>
        pair<iterator, iterator>
        __equal_range_multi(const _Key& __k);
    template <class _Key>
        pair<const_iterator, const_iterator>
        __equal_range_multi(const _Key& __k) const;

    typedef __tree_node_destructor<__node_allocator> _Dp;
    typedef unique_ptr<__node, _Dp> __node_holder;

    __node_holder remove(const_iterator __p) _NOEXCEPT;
private:
    __node_base_pointer&
        __find_leaf_low(__parent_pointer& __parent, const key_type& __v);
    __node_base_pointer&
        __find_leaf_high(__parent_pointer& __parent, const key_type& __v);
    __node_base_pointer&
        __find_leaf(const_iterator __hint,
                    __parent_pointer& __parent, const key_type& __v);
    // FIXME: Make this function const qualified. Unfortunately doing so
    // breaks existing code which uses non-const callable comparators.
    template <class _Key>
    __node_base_pointer&
        __find_equal(__parent_pointer& __parent, const _Key& __v);
    template <class _Key>
    _LIBCPP_INLINE_VISIBILITY __node_base_pointer&
    __find_equal(__parent_pointer& __parent, const _Key& __v) const {
      return const_cast<__tree*>(this)->__find_equal(__parent, __v);
    }
    template <class _Key>
    __node_base_pointer&
        __find_equal(const_iterator __hint, __parent_pointer& __parent,
                     __node_base_pointer& __dummy,
                     const _Key& __v);

    template <class ..._Args>
    __node_holder __construct_node(_Args&& ...__args);

    void destroy(__node_pointer __nd) _NOEXCEPT;

    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __tree& __t)
        {__copy_assign_alloc(__t, integral_constant<bool,
             __node_traits::propagate_on_container_copy_assignment::value>());}

    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __tree& __t, true_type)
        {
        if (__node_alloc() != __t.__node_alloc())
            clear();
        __node_alloc() = __t.__node_alloc();
        }
    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __tree&, false_type) {}

    void __move_assign(__tree& __t, false_type);
    void __move_assign(__tree& __t, true_type)
        _NOEXCEPT_(is_nothrow_move_assignable<value_compare>::value &&
                   is_nothrow_move_assignable<__node_allocator>::value);

    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(__tree& __t)
        _NOEXCEPT_(
            !__node_traits::propagate_on_container_move_assignment::value ||
            is_nothrow_move_assignable<__node_allocator>::value)
        {__move_assign_alloc(__t, integral_constant<bool,
             __node_traits::propagate_on_container_move_assignment::value>());}

    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(__tree& __t, true_type)
        _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value)
        {__node_alloc() = _VSTD::move(__t.__node_alloc());}
    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(__tree&, false_type) _NOEXCEPT {}

    struct _DetachedTreeCache {
      _LIBCPP_INLINE_VISIBILITY
      explicit _DetachedTreeCache(__tree *__t) _NOEXCEPT : __t_(__t),
        __cache_root_(__detach_from_tree(__t)) {
          __advance();
        }

      _LIBCPP_INLINE_VISIBILITY
      __node_pointer __get() const _NOEXCEPT {
        return __cache_elem_;
      }

      _LIBCPP_INLINE_VISIBILITY
      void __advance() _NOEXCEPT {
        __cache_elem_ = __cache_root_;
        if (__cache_root_) {
          __cache_root_ = __detach_next(__cache_root_);
        }
      }

      _LIBCPP_INLINE_VISIBILITY
      ~_DetachedTreeCache() {
        __t_->destroy(__cache_elem_);
        if (__cache_root_) {
          while (__cache_root_->__parent_ != nullptr)
            __cache_root_ = static_cast<__node_pointer>(__cache_root_->__parent_);
          __t_->destroy(__cache_root_);
        }
      }

       _DetachedTreeCache(_DetachedTreeCache const&) = delete;
       _DetachedTreeCache& operator=(_DetachedTreeCache const&) = delete;

    private:
      _LIBCPP_INLINE_VISIBILITY
      static __node_pointer __detach_from_tree(__tree *__t) _NOEXCEPT;
      _LIBCPP_INLINE_VISIBILITY
      static __node_pointer __detach_next(__node_pointer) _NOEXCEPT;

      __tree *__t_;
      __node_pointer __cache_root_;
      __node_pointer __cache_elem_;
    };


    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS map;
    template <class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS multimap;
};

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(const value_compare& __comp)
        _NOEXCEPT_(
            is_nothrow_default_constructible<__node_allocator>::value &&
            is_nothrow_copy_constructible<value_compare>::value)
    : __pair3_(0, __comp)
{
    __begin_node() = __end_node();
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(const allocator_type& __a)
    : __begin_node_(__iter_pointer()),
      __pair1_(__default_init_tag(), __node_allocator(__a)),
      __pair3_(0, __default_init_tag())
{
    __begin_node() = __end_node();
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(const value_compare& __comp,
                                           const allocator_type& __a)
    : __begin_node_(__iter_pointer()),
      __pair1_(__default_init_tag(), __node_allocator(__a)),
      __pair3_(0, __comp)
{
    __begin_node() = __end_node();
}

// Precondition:  size() != 0
template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_pointer
__tree<_Tp, _Compare, _Allocator>::_DetachedTreeCache::__detach_from_tree(__tree *__t) _NOEXCEPT
{
    __node_pointer __cache = static_cast<__node_pointer>(__t->__begin_node());
    __t->__begin_node() = __t->__end_node();
    __t->__end_node()->__left_->__parent_ = nullptr;
    __t->__end_node()->__left_ = nullptr;
    __t->size() = 0;
    // __cache->__left_ == nullptr
    if (__cache->__right_ != nullptr)
        __cache = static_cast<__node_pointer>(__cache->__right_);
    // __cache->__left_ == nullptr
    // __cache->__right_ == nullptr
    return __cache;
}

// Precondition:  __cache != nullptr
//    __cache->left_ == nullptr
//    __cache->right_ == nullptr
//    This is no longer a red-black tree
template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_pointer
__tree<_Tp, _Compare, _Allocator>::_DetachedTreeCache::__detach_next(__node_pointer __cache) _NOEXCEPT
{
    if (__cache->__parent_ == nullptr)
        return nullptr;
    if (_VSTD::__tree_is_left_child(static_cast<__node_base_pointer>(__cache)))
    {
        __cache->__parent_->__left_ = nullptr;
        __cache = static_cast<__node_pointer>(__cache->__parent_);
        if (__cache->__right_ == nullptr)
            return __cache;
        return static_cast<__node_pointer>(_VSTD::__tree_leaf(__cache->__right_));
    }
    // __cache is right child
    __cache->__parent_unsafe()->__right_ = nullptr;
    __cache = static_cast<__node_pointer>(__cache->__parent_);
    if (__cache->__left_ == nullptr)
        return __cache;
    return static_cast<__node_pointer>(_VSTD::__tree_leaf(__cache->__left_));
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>&
__tree<_Tp, _Compare, _Allocator>::operator=(const __tree& __t)
{
    if (this != _VSTD::addressof(__t))
    {
        value_comp() = __t.value_comp();
        __copy_assign_alloc(__t);
        __assign_multi(__t.begin(), __t.end());
    }
    return *this;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _ForwardIterator>
void
__tree<_Tp, _Compare, _Allocator>::__assign_unique(_ForwardIterator __first, _ForwardIterator __last)
{
    typedef iterator_traits<_ForwardIterator> _ITraits;
    typedef typename _ITraits::value_type _ItValueType;
    static_assert((is_same<_ItValueType, __container_value_type>::value),
                  "__assign_unique may only be called with the containers value type");
    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
                  "__assign_unique requires a forward iterator");
    if (size() != 0)
    {
        _DetachedTreeCache __cache(this);
          for (; __cache.__get() != nullptr && __first != __last; ++__first) {
              if (__node_assign_unique(*__first, __cache.__get()).second)
                  __cache.__advance();
            }
    }
    for (; __first != __last; ++__first)
        __insert_unique(*__first);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _InputIterator>
void
__tree<_Tp, _Compare, _Allocator>::__assign_multi(_InputIterator __first, _InputIterator __last)
{
    typedef iterator_traits<_InputIterator> _ITraits;
    typedef typename _ITraits::value_type _ItValueType;
    static_assert((is_same<_ItValueType, __container_value_type>::value ||
                  is_same<_ItValueType, __node_value_type>::value),
                  "__assign_multi may only be called with the containers value type"
                  " or the nodes value type");
    if (size() != 0)
    {
        _DetachedTreeCache __cache(this);
        for (; __cache.__get() && __first != __last; ++__first) {
            __cache.__get()->__value_ = *__first;
            __node_insert_multi(__cache.__get());
            __cache.__advance();
        }
    }
    for (; __first != __last; ++__first)
        __insert_multi(_NodeTypes::__get_value(*__first));
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(const __tree& __t)
    : __begin_node_(__iter_pointer()),
      __pair1_(__default_init_tag(), __node_traits::select_on_container_copy_construction(__t.__node_alloc())),
      __pair3_(0, __t.value_comp())
{
    __begin_node() = __end_node();
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t)
    _NOEXCEPT_(
        is_nothrow_move_constructible<__node_allocator>::value &&
        is_nothrow_move_constructible<value_compare>::value)
    : __begin_node_(_VSTD::move(__t.__begin_node_)),
      __pair1_(_VSTD::move(__t.__pair1_)),
      __pair3_(_VSTD::move(__t.__pair3_))
{
    if (size() == 0)
        __begin_node() = __end_node();
    else
    {
        __end_node()->__left_->__parent_ = static_cast<__parent_pointer>(__end_node());
        __t.__begin_node() = __t.__end_node();
        __t.__end_node()->__left_ = nullptr;
        __t.size() = 0;
    }
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t, const allocator_type& __a)
    : __pair1_(__default_init_tag(), __node_allocator(__a)),
      __pair3_(0, _VSTD::move(__t.value_comp()))
{
    if (__a == __t.__alloc())
    {
        if (__t.size() == 0)
            __begin_node() = __end_node();
        else
        {
            __begin_node() = __t.__begin_node();
            __end_node()->__left_ = __t.__end_node()->__left_;
            __end_node()->__left_->__parent_ = static_cast<__parent_pointer>(__end_node());
            size() = __t.size();
            __t.__begin_node() = __t.__end_node();
            __t.__end_node()->__left_ = nullptr;
            __t.size() = 0;
        }
    }
    else
    {
        __begin_node() = __end_node();
    }
}

template <class _Tp, class _Compare, class _Allocator>
void
__tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, true_type)
    _NOEXCEPT_(is_nothrow_move_assignable<value_compare>::value &&
               is_nothrow_move_assignable<__node_allocator>::value)
{
    destroy(static_cast<__node_pointer>(__end_node()->__left_));
    __begin_node_ = __t.__begin_node_;
    __pair1_.first() = __t.__pair1_.first();
    __move_assign_alloc(__t);
    __pair3_ = _VSTD::move(__t.__pair3_);
    if (size() == 0)
        __begin_node() = __end_node();
    else
    {
        __end_node()->__left_->__parent_ = static_cast<__parent_pointer>(__end_node());
        __t.__begin_node() = __t.__end_node();
        __t.__end_node()->__left_ = nullptr;
        __t.size() = 0;
    }
}

template <class _Tp, class _Compare, class _Allocator>
void
__tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, false_type)
{
    if (__node_alloc() == __t.__node_alloc())
        __move_assign(__t, true_type());
    else
    {
        value_comp() = _VSTD::move(__t.value_comp());
        const_iterator __e = end();
        if (size() != 0)
        {
            _DetachedTreeCache __cache(this);
            while (__cache.__get() != nullptr && __t.size() != 0) {
              __cache.__get()->__value_ = _VSTD::move(__t.remove(__t.begin())->__value_);
              __node_insert_multi(__cache.__get());
              __cache.__advance();
            }
        }
        while (__t.size() != 0)
            __insert_multi(__e, _NodeTypes::__move(__t.remove(__t.begin())->__value_));
    }
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>&
__tree<_Tp, _Compare, _Allocator>::operator=(__tree&& __t)
    _NOEXCEPT_(
        __node_traits::propagate_on_container_move_assignment::value &&
        is_nothrow_move_assignable<value_compare>::value &&
        is_nothrow_move_assignable<__node_allocator>::value)

{
    __move_assign(__t, integral_constant<bool,
                  __node_traits::propagate_on_container_move_assignment::value>());
    return *this;
}

template <class _Tp, class _Compare, class _Allocator>
__tree<_Tp, _Compare, _Allocator>::~__tree()
{
    static_assert((is_copy_constructible<value_compare>::value),
                 "Comparator must be copy-constructible.");
  destroy(__root());
}

template <class _Tp, class _Compare, class _Allocator>
void
__tree<_Tp, _Compare, _Allocator>::destroy(__node_pointer __nd) _NOEXCEPT
{
    if (__nd != nullptr)
    {
        destroy(static_cast<__node_pointer>(__nd->__left_));
        destroy(static_cast<__node_pointer>(__nd->__right_));
        __node_allocator& __na = __node_alloc();
        __node_traits::destroy(__na, _NodeTypes::__get_ptr(__nd->__value_));
        __node_traits::deallocate(__na, __nd, 1);
    }
}

template <class _Tp, class _Compare, class _Allocator>
void
__tree<_Tp, _Compare, _Allocator>::swap(__tree& __t)
#if _LIBCPP_STD_VER <= 11
        _NOEXCEPT_(
            __is_nothrow_swappable<value_compare>::value
            && (!__node_traits::propagate_on_container_swap::value ||
                 __is_nothrow_swappable<__node_allocator>::value)
            )
#else
        _NOEXCEPT_(__is_nothrow_swappable<value_compare>::value)
#endif
{
    using _VSTD::swap;
    swap(__begin_node_, __t.__begin_node_);
    swap(__pair1_.first(), __t.__pair1_.first());
    _VSTD::__swap_allocator(__node_alloc(), __t.__node_alloc());
    __pair3_.swap(__t.__pair3_);
    if (size() == 0)
        __begin_node() = __end_node();
    else
        __end_node()->__left_->__parent_ = static_cast<__parent_pointer>(__end_node());
    if (__t.size() == 0)
        __t.__begin_node() = __t.__end_node();
    else
        __t.__end_node()->__left_->__parent_ = static_cast<__parent_pointer>(__t.__end_node());
}

template <class _Tp, class _Compare, class _Allocator>
void
__tree<_Tp, _Compare, _Allocator>::clear() _NOEXCEPT
{
    destroy(__root());
    size() = 0;
    __begin_node() = __end_node();
    __end_node()->__left_ = nullptr;
}

// Find lower_bound place to insert
// Set __parent to parent of null leaf
// Return reference to null leaf
template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
__tree<_Tp, _Compare, _Allocator>::__find_leaf_low(__parent_pointer& __parent,
                                                   const key_type& __v)
{
    __node_pointer __nd = __root();
    if (__nd != nullptr)
    {
        while (true)
        {
            if (value_comp()(__nd->__value_, __v))
            {
                if (__nd->__right_ != nullptr)
                    __nd = static_cast<__node_pointer>(__nd->__right_);
                else
                {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __nd->__right_;
                }
            }
            else
            {
                if (__nd->__left_ != nullptr)
                    __nd = static_cast<__node_pointer>(__nd->__left_);
                else
                {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __parent->__left_;
                }
            }
        }
    }
    __parent = static_cast<__parent_pointer>(__end_node());
    return __parent->__left_;
}

// Find upper_bound place to insert
// Set __parent to parent of null leaf
// Return reference to null leaf
template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
__tree<_Tp, _Compare, _Allocator>::__find_leaf_high(__parent_pointer& __parent,
                                                    const key_type& __v)
{
    __node_pointer __nd = __root();
    if (__nd != nullptr)
    {
        while (true)
        {
            if (value_comp()(__v, __nd->__value_))
            {
                if (__nd->__left_ != nullptr)
                    __nd = static_cast<__node_pointer>(__nd->__left_);
                else
                {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __parent->__left_;
                }
            }
            else
            {
                if (__nd->__right_ != nullptr)
                    __nd = static_cast<__node_pointer>(__nd->__right_);
                else
                {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __nd->__right_;
                }
            }
        }
    }
    __parent = static_cast<__parent_pointer>(__end_node());
    return __parent->__left_;
}

// Find leaf place to insert closest to __hint
// First check prior to __hint.
// Next check after __hint.
// Next do O(log N) search.
// Set __parent to parent of null leaf
// Return reference to null leaf
template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
__tree<_Tp, _Compare, _Allocator>::__find_leaf(const_iterator __hint,
                                               __parent_pointer& __parent,
                                               const key_type& __v)
{
    if (__hint == end() || !value_comp()(*__hint, __v))  // check before
    {
        // __v <= *__hint
        const_iterator __prior = __hint;
        if (__prior == begin() || !value_comp()(__v, *--__prior))
        {
            // *prev(__hint) <= __v <= *__hint
            if (__hint.__ptr_->__left_ == nullptr)
            {
                __parent = static_cast<__parent_pointer>(__hint.__ptr_);
                return __parent->__left_;
            }
            else
            {
                __parent = static_cast<__parent_pointer>(__prior.__ptr_);
                return static_cast<__node_base_pointer>(__prior.__ptr_)->__right_;
            }
        }
        // __v < *prev(__hint)
        return __find_leaf_high(__parent, __v);
    }
    // else __v > *__hint
    return __find_leaf_low(__parent, __v);
}

// Find place to insert if __v doesn't exist
// Set __parent to parent of null leaf
// Return reference to null leaf
// If __v exists, set parent to node of __v and return reference to node of __v
template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
__tree<_Tp, _Compare, _Allocator>::__find_equal(__parent_pointer& __parent,
                                                const _Key& __v)
{
    __node_pointer __nd = __root();
    __node_base_pointer* __nd_ptr = __root_ptr();
    if (__nd != nullptr)
    {
        while (true)
        {
            if (value_comp()(__v, __nd->__value_))
            {
                if (__nd->__left_ != nullptr) {
                    __nd_ptr = _VSTD::addressof(__nd->__left_);
                    __nd = static_cast<__node_pointer>(__nd->__left_);
                } else {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __parent->__left_;
                }
            }
            else if (value_comp()(__nd->__value_, __v))
            {
                if (__nd->__right_ != nullptr) {
                    __nd_ptr = _VSTD::addressof(__nd->__right_);
                    __nd = static_cast<__node_pointer>(__nd->__right_);
                } else {
                    __parent = static_cast<__parent_pointer>(__nd);
                    return __nd->__right_;
                }
            }
            else
            {
                __parent = static_cast<__parent_pointer>(__nd);
                return *__nd_ptr;
            }
        }
    }
    __parent = static_cast<__parent_pointer>(__end_node());
    return __parent->__left_;
}

// Find place to insert if __v doesn't exist
// First check prior to __hint.
// Next check after __hint.
// Next do O(log N) search.
// Set __parent to parent of null leaf
// Return reference to null leaf
// If __v exists, set parent to node of __v and return reference to node of __v
template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
__tree<_Tp, _Compare, _Allocator>::__find_equal(const_iterator __hint,
                                                __parent_pointer& __parent,
                                                __node_base_pointer& __dummy,
                                                const _Key& __v)
{
    if (__hint == end() || value_comp()(__v, *__hint))  // check before
    {
        // __v < *__hint
        const_iterator __prior = __hint;
        if (__prior == begin() || value_comp()(*--__prior, __v))
        {
            // *prev(__hint) < __v < *__hint
            if (__hint.__ptr_->__left_ == nullptr)
            {
                __parent = static_cast<__parent_pointer>(__hint.__ptr_);
                return __parent->__left_;
            }
            else
            {
                __parent = static_cast<__parent_pointer>(__prior.__ptr_);
                return static_cast<__node_base_pointer>(__prior.__ptr_)->__right_;
            }
        }
        // __v <= *prev(__hint)
        return __find_equal(__parent, __v);
    }
    else if (value_comp()(*__hint, __v))  // check after
    {
        // *__hint < __v
        const_iterator __next = _VSTD::next(__hint);
        if (__next == end() || value_comp()(__v, *__next))
        {
            // *__hint < __v < *_VSTD::next(__hint)
            if (__hint.__get_np()->__right_ == nullptr)
            {
                __parent = static_cast<__parent_pointer>(__hint.__ptr_);
                return static_cast<__node_base_pointer>(__hint.__ptr_)->__right_;
            }
            else
            {
                __parent = static_cast<__parent_pointer>(__next.__ptr_);
                return __parent->__left_;
            }
        }
        // *next(__hint) <= __v
        return __find_equal(__parent, __v);
    }
    // else __v == *__hint
    __parent = static_cast<__parent_pointer>(__hint.__ptr_);
    __dummy = static_cast<__node_base_pointer>(__hint.__ptr_);
    return __dummy;
}

template <class _Tp, class _Compare, class _Allocator>
void __tree<_Tp, _Compare, _Allocator>::__insert_node_at(
    __parent_pointer __parent, __node_base_pointer& __child,
    __node_base_pointer __new_node) _NOEXCEPT
{
    __new_node->__left_   = nullptr;
    __new_node->__right_  = nullptr;
    __new_node->__parent_ = __parent;
    // __new_node->__is_black_ is initialized in __tree_balance_after_insert
    __child = __new_node;
    if (__begin_node()->__left_ != nullptr)
        __begin_node() = static_cast<__iter_pointer>(__begin_node()->__left_);
    _VSTD::__tree_balance_after_insert(__end_node()->__left_, __child);
    ++size();
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key, class... _Args>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, bool>
__tree<_Tp, _Compare, _Allocator>::__emplace_unique_key_args(_Key const& __k, _Args&&... __args)
{
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_equal(__parent, __k);
    __node_pointer __r = static_cast<__node_pointer>(__child);
    bool __inserted = false;
    if (__child == nullptr)
    {
        __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
        __r = __h.release();
        __inserted = true;
    }
    return pair<iterator, bool>(iterator(__r), __inserted);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key, class... _Args>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, bool>
__tree<_Tp, _Compare, _Allocator>::__emplace_hint_unique_key_args(
    const_iterator __p, _Key const& __k, _Args&&... __args)
{
    __parent_pointer __parent;
    __node_base_pointer __dummy;
    __node_base_pointer& __child = __find_equal(__p, __parent, __dummy, __k);
    __node_pointer __r = static_cast<__node_pointer>(__child);
    bool __inserted = false;
    if (__child == nullptr)
    {
        __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
        __r = __h.release();
        __inserted = true;
    }
    return pair<iterator, bool>(iterator(__r), __inserted);
}

template <class _Tp, class _Compare, class _Allocator>
template <class ..._Args>
typename __tree<_Tp, _Compare, _Allocator>::__node_holder
__tree<_Tp, _Compare, _Allocator>::__construct_node(_Args&& ...__args)
{
    static_assert(!__is_tree_value_type<_Args...>::value,
                  "Cannot construct from __value_type");
    __node_allocator& __na = __node_alloc();
    __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
    __node_traits::construct(__na, _NodeTypes::__get_ptr(__h->__value_), _VSTD::forward<_Args>(__args)...);
    __h.get_deleter().__value_constructed = true;
    return __h;
}


template <class _Tp, class _Compare, class _Allocator>
template <class... _Args>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, bool>
__tree<_Tp, _Compare, _Allocator>::__emplace_unique_impl(_Args&&... __args)
{
    __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_equal(__parent, __h->__value_);
    __node_pointer __r = static_cast<__node_pointer>(__child);
    bool __inserted = false;
    if (__child == nullptr)
    {
        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
        __r = __h.release();
        __inserted = true;
    }
    return pair<iterator, bool>(iterator(__r), __inserted);
}

template <class _Tp, class _Compare, class _Allocator>
template <class... _Args>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__emplace_hint_unique_impl(const_iterator __p, _Args&&... __args)
{
    __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
    __parent_pointer __parent;
    __node_base_pointer __dummy;
    __node_base_pointer& __child = __find_equal(__p, __parent, __dummy, __h->__value_);
    __node_pointer __r = static_cast<__node_pointer>(__child);
    if (__child == nullptr)
    {
        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
        __r = __h.release();
    }
    return iterator(__r);
}

template <class _Tp, class _Compare, class _Allocator>
template <class... _Args>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__emplace_multi(_Args&&... __args)
{
    __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf_high(__parent, _NodeTypes::__get_key(__h->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
    return iterator(static_cast<__node_pointer>(__h.release()));
}

template <class _Tp, class _Compare, class _Allocator>
template <class... _Args>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__emplace_hint_multi(const_iterator __p,
                                                        _Args&&... __args)
{
    __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf(__p, __parent, _NodeTypes::__get_key(__h->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
    return iterator(static_cast<__node_pointer>(__h.release()));
}

template <class _Tp, class _Compare, class _Allocator>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, bool>
__tree<_Tp, _Compare, _Allocator>::__node_assign_unique(const __container_value_type& __v, __node_pointer __nd)
{
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_equal(__parent, _NodeTypes::__get_key(__v));
    __node_pointer __r = static_cast<__node_pointer>(__child);
    bool __inserted = false;
    if (__child == nullptr)
    {
        __nd->__value_ = __v;
        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
        __r = __nd;
        __inserted = true;
    }
    return pair<iterator, bool>(iterator(__r), __inserted);
}


template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__node_insert_multi(__node_pointer __nd)
{
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf_high(__parent, _NodeTypes::__get_key(__nd->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
    return iterator(__nd);
}

template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__node_insert_multi(const_iterator __p,
                                                       __node_pointer __nd)
{
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf(__p, __parent, _NodeTypes::__get_key(__nd->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
    return iterator(__nd);
}

template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__remove_node_pointer(__node_pointer __ptr) _NOEXCEPT
{
    iterator __r(__ptr);
    ++__r;
    if (__begin_node() == __ptr)
        __begin_node() = __r.__ptr_;
    --size();
    _VSTD::__tree_remove(__end_node()->__left_,
                         static_cast<__node_base_pointer>(__ptr));
    return __r;
}

#if _LIBCPP_STD_VER > 14
template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle, class _InsertReturnType>
_LIBCPP_INLINE_VISIBILITY
_InsertReturnType
__tree<_Tp, _Compare, _Allocator>::__node_handle_insert_unique(
    _NodeHandle&& __nh)
{
    if (__nh.empty())
        return _InsertReturnType{end(), false, _NodeHandle()};

    __node_pointer __ptr = __nh.__ptr_;
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_equal(__parent,
                                                __ptr->__value_);
    if (__child != nullptr)
        return _InsertReturnType{
            iterator(static_cast<__node_pointer>(__child)),
            false, _VSTD::move(__nh)};

    __insert_node_at(__parent, __child,
                     static_cast<__node_base_pointer>(__ptr));
    __nh.__release_ptr();
    return _InsertReturnType{iterator(__ptr), true, _NodeHandle()};
}

template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle>
_LIBCPP_INLINE_VISIBILITY
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__node_handle_insert_unique(
    const_iterator __hint, _NodeHandle&& __nh)
{
    if (__nh.empty())
        return end();

    __node_pointer __ptr = __nh.__ptr_;
    __parent_pointer __parent;
    __node_base_pointer __dummy;
    __node_base_pointer& __child = __find_equal(__hint, __parent, __dummy,
                                                __ptr->__value_);
    __node_pointer __r = static_cast<__node_pointer>(__child);
    if (__child == nullptr)
    {
        __insert_node_at(__parent, __child,
                         static_cast<__node_base_pointer>(__ptr));
        __r = __ptr;
        __nh.__release_ptr();
    }
    return iterator(__r);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle>
_LIBCPP_INLINE_VISIBILITY
_NodeHandle
__tree<_Tp, _Compare, _Allocator>::__node_handle_extract(key_type const& __key)
{
    iterator __it = find(__key);
    if (__it == end())
        return _NodeHandle();
    return __node_handle_extract<_NodeHandle>(__it);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle>
_LIBCPP_INLINE_VISIBILITY
_NodeHandle
__tree<_Tp, _Compare, _Allocator>::__node_handle_extract(const_iterator __p)
{
    __node_pointer __np = __p.__get_np();
    __remove_node_pointer(__np);
    return _NodeHandle(__np, __alloc());
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Tree>
_LIBCPP_INLINE_VISIBILITY
void
__tree<_Tp, _Compare, _Allocator>::__node_handle_merge_unique(_Tree& __source)
{
    static_assert(is_same<typename _Tree::__node_pointer, __node_pointer>::value, "");

    for (typename _Tree::iterator __i = __source.begin();
         __i != __source.end();)
    {
        __node_pointer __src_ptr = __i.__get_np();
        __parent_pointer __parent;
        __node_base_pointer& __child =
            __find_equal(__parent, _NodeTypes::__get_key(__src_ptr->__value_));
        ++__i;
        if (__child != nullptr)
            continue;
        __source.__remove_node_pointer(__src_ptr);
        __insert_node_at(__parent, __child,
                         static_cast<__node_base_pointer>(__src_ptr));
    }
}

template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle>
_LIBCPP_INLINE_VISIBILITY
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__node_handle_insert_multi(_NodeHandle&& __nh)
{
    if (__nh.empty())
        return end();
    __node_pointer __ptr = __nh.__ptr_;
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf_high(
        __parent, _NodeTypes::__get_key(__ptr->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
    __nh.__release_ptr();
    return iterator(__ptr);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _NodeHandle>
_LIBCPP_INLINE_VISIBILITY
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__node_handle_insert_multi(
    const_iterator __hint, _NodeHandle&& __nh)
{
    if (__nh.empty())
        return end();

    __node_pointer __ptr = __nh.__ptr_;
    __parent_pointer __parent;
    __node_base_pointer& __child = __find_leaf(__hint, __parent,
                                               _NodeTypes::__get_key(__ptr->__value_));
    __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
    __nh.__release_ptr();
    return iterator(__ptr);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Tree>
_LIBCPP_INLINE_VISIBILITY
void
__tree<_Tp, _Compare, _Allocator>::__node_handle_merge_multi(_Tree& __source)
{
    static_assert(is_same<typename _Tree::__node_pointer, __node_pointer>::value, "");

    for (typename _Tree::iterator __i = __source.begin();
         __i != __source.end();)
    {
        __node_pointer __src_ptr = __i.__get_np();
        __parent_pointer __parent;
        __node_base_pointer& __child = __find_leaf_high(
            __parent, _NodeTypes::__get_key(__src_ptr->__value_));
        ++__i;
        __source.__remove_node_pointer(__src_ptr);
        __insert_node_at(__parent, __child,
                         static_cast<__node_base_pointer>(__src_ptr));
    }
}

#endif // _LIBCPP_STD_VER > 14

template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::erase(const_iterator __p)
{
    __node_pointer __np = __p.__get_np();
    iterator __r = __remove_node_pointer(__np);
    __node_allocator& __na = __node_alloc();
    __node_traits::destroy(__na, _NodeTypes::__get_ptr(
        const_cast<__node_value_type&>(*__p)));
    __node_traits::deallocate(__na, __np, 1);
    return __r;
}

template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::erase(const_iterator __f, const_iterator __l)
{
    while (__f != __l)
        __f = erase(__f);
    return iterator(__l.__ptr_);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::size_type
__tree<_Tp, _Compare, _Allocator>::__erase_unique(const _Key& __k)
{
    iterator __i = find(__k);
    if (__i == end())
        return 0;
    erase(__i);
    return 1;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::size_type
__tree<_Tp, _Compare, _Allocator>::__erase_multi(const _Key& __k)
{
    pair<iterator, iterator> __p = __equal_range_multi(__k);
    size_type __r = 0;
    for (; __p.first != __p.second; ++__r)
        __p.first = erase(__p.first);
    return __r;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::find(const _Key& __v)
{
    iterator __p = __lower_bound(__v, __root(), __end_node());
    if (__p != end() && !value_comp()(__v, *__p))
        return __p;
    return end();
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::const_iterator
__tree<_Tp, _Compare, _Allocator>::find(const _Key& __v) const
{
    const_iterator __p = __lower_bound(__v, __root(), __end_node());
    if (__p != end() && !value_comp()(__v, *__p))
        return __p;
    return end();
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::size_type
__tree<_Tp, _Compare, _Allocator>::__count_unique(const _Key& __k) const
{
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return 1;
    }
    return 0;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::size_type
__tree<_Tp, _Compare, _Allocator>::__count_multi(const _Key& __k) const
{
    __iter_pointer __result = __end_node();
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __result = static_cast<__iter_pointer>(__rt);
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return _VSTD::distance(
                __lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__iter_pointer>(__rt)),
                __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result)
            );
    }
    return 0;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__lower_bound(const _Key& __v,
                                                 __node_pointer __root,
                                                 __iter_pointer __result)
{
    while (__root != nullptr)
    {
        if (!value_comp()(__root->__value_, __v))
        {
            __result = static_cast<__iter_pointer>(__root);
            __root = static_cast<__node_pointer>(__root->__left_);
        }
        else
            __root = static_cast<__node_pointer>(__root->__right_);
    }
    return iterator(__result);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::const_iterator
__tree<_Tp, _Compare, _Allocator>::__lower_bound(const _Key& __v,
                                                 __node_pointer __root,
                                                 __iter_pointer __result) const
{
    while (__root != nullptr)
    {
        if (!value_comp()(__root->__value_, __v))
        {
            __result = static_cast<__iter_pointer>(__root);
            __root = static_cast<__node_pointer>(__root->__left_);
        }
        else
            __root = static_cast<__node_pointer>(__root->__right_);
    }
    return const_iterator(__result);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::iterator
__tree<_Tp, _Compare, _Allocator>::__upper_bound(const _Key& __v,
                                                 __node_pointer __root,
                                                 __iter_pointer __result)
{
    while (__root != nullptr)
    {
        if (value_comp()(__v, __root->__value_))
        {
            __result = static_cast<__iter_pointer>(__root);
            __root = static_cast<__node_pointer>(__root->__left_);
        }
        else
            __root = static_cast<__node_pointer>(__root->__right_);
    }
    return iterator(__result);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::const_iterator
__tree<_Tp, _Compare, _Allocator>::__upper_bound(const _Key& __v,
                                                 __node_pointer __root,
                                                 __iter_pointer __result) const
{
    while (__root != nullptr)
    {
        if (value_comp()(__v, __root->__value_))
        {
            __result = static_cast<__iter_pointer>(__root);
            __root = static_cast<__node_pointer>(__root->__left_);
        }
        else
            __root = static_cast<__node_pointer>(__root->__right_);
    }
    return const_iterator(__result);
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator,
     typename __tree<_Tp, _Compare, _Allocator>::iterator>
__tree<_Tp, _Compare, _Allocator>::__equal_range_unique(const _Key& __k)
{
    typedef pair<iterator, iterator> _Pp;
    __iter_pointer __result = __end_node();
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __result = static_cast<__iter_pointer>(__rt);
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return _Pp(iterator(__rt),
                      iterator(
                          __rt->__right_ != nullptr ?
                              static_cast<__iter_pointer>(_VSTD::__tree_min(__rt->__right_))
                            : __result));
    }
    return _Pp(iterator(__result), iterator(__result));
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
pair<typename __tree<_Tp, _Compare, _Allocator>::const_iterator,
     typename __tree<_Tp, _Compare, _Allocator>::const_iterator>
__tree<_Tp, _Compare, _Allocator>::__equal_range_unique(const _Key& __k) const
{
    typedef pair<const_iterator, const_iterator> _Pp;
    __iter_pointer __result = __end_node();
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __result = static_cast<__iter_pointer>(__rt);
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return _Pp(const_iterator(__rt),
                      const_iterator(
                          __rt->__right_ != nullptr ?
                              static_cast<__iter_pointer>(_VSTD::__tree_min(__rt->__right_))
                            : __result));
    }
    return _Pp(const_iterator(__result), const_iterator(__result));
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
pair<typename __tree<_Tp, _Compare, _Allocator>::iterator,
     typename __tree<_Tp, _Compare, _Allocator>::iterator>
__tree<_Tp, _Compare, _Allocator>::__equal_range_multi(const _Key& __k)
{
    typedef pair<iterator, iterator> _Pp;
    __iter_pointer __result = __end_node();
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __result = static_cast<__iter_pointer>(__rt);
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return _Pp(__lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__iter_pointer>(__rt)),
                      __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result));
    }
    return _Pp(iterator(__result), iterator(__result));
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
pair<typename __tree<_Tp, _Compare, _Allocator>::const_iterator,
     typename __tree<_Tp, _Compare, _Allocator>::const_iterator>
__tree<_Tp, _Compare, _Allocator>::__equal_range_multi(const _Key& __k) const
{
    typedef pair<const_iterator, const_iterator> _Pp;
    __iter_pointer __result = __end_node();
    __node_pointer __rt = __root();
    while (__rt != nullptr)
    {
        if (value_comp()(__k, __rt->__value_))
        {
            __result = static_cast<__iter_pointer>(__rt);
            __rt = static_cast<__node_pointer>(__rt->__left_);
        }
        else if (value_comp()(__rt->__value_, __k))
            __rt = static_cast<__node_pointer>(__rt->__right_);
        else
            return _Pp(__lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__iter_pointer>(__rt)),
                      __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result));
    }
    return _Pp(const_iterator(__result), const_iterator(__result));
}

template <class _Tp, class _Compare, class _Allocator>
typename __tree<_Tp, _Compare, _Allocator>::__node_holder
__tree<_Tp, _Compare, _Allocator>::remove(const_iterator __p) _NOEXCEPT
{
    __node_pointer __np = __p.__get_np();
    if (__begin_node() == __p.__ptr_)
    {
        if (__np->__right_ != nullptr)
            __begin_node() = static_cast<__iter_pointer>(__np->__right_);
        else
            __begin_node() = static_cast<__iter_pointer>(__np->__parent_);
    }
    --size();
    _VSTD::__tree_remove(__end_node()->__left_,
                         static_cast<__node_base_pointer>(__np));
    return __node_holder(__np, _Dp(__node_alloc(), true));
}

template <class _Tp, class _Compare, class _Allocator>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(__tree<_Tp, _Compare, _Allocator>& __x,
     __tree<_Tp, _Compare, _Allocator>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___TREE