summaryrefslogtreecommitdiff
path: root/absl/container/internal/inlined_vector.h
blob: 7954b2b51889002601de714ebd7ee8361e56b6aa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
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
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
// Copyright 2019 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_
#define ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_

#include <cstddef>
#include <cstring>
#include <iterator>
#include <memory>
#include <utility>

#include "absl/base/macros.h"
#include "absl/container/internal/compressed_tuple.h"
#include "absl/memory/memory.h"
#include "absl/meta/type_traits.h"
#include "absl/types/span.h"

namespace absl {
namespace inlined_vector_internal {

template <typename Iterator>
using IsAtLeastForwardIterator = std::is_convertible<
    typename std::iterator_traits<Iterator>::iterator_category,
    std::forward_iterator_tag>;

template <typename AllocatorType>
using IsMemcpyOk = absl::conjunction<
    std::is_same<std::allocator<typename AllocatorType::value_type>,
                 AllocatorType>,
    absl::is_trivially_copy_constructible<typename AllocatorType::value_type>,
    absl::is_trivially_copy_assignable<typename AllocatorType::value_type>,
    absl::is_trivially_destructible<typename AllocatorType::value_type>>;

template <typename AllocatorType, typename ValueType, typename SizeType>
void DestroyElements(AllocatorType* alloc_ptr, ValueType* destroy_first,
                     SizeType destroy_size) {
  using AllocatorTraits = absl::allocator_traits<AllocatorType>;

  if (destroy_first != nullptr) {
    for (auto i = destroy_size; i != 0;) {
      --i;
      AllocatorTraits::destroy(*alloc_ptr, destroy_first + i);
    }

#ifndef NDEBUG
    // Overwrite unused memory with `0xab` so we can catch uninitialized usage.
    //
    // Cast to `void*` to tell the compiler that we don't care that we might be
    // scribbling on a vtable pointer.
    auto* memory_ptr = static_cast<void*>(destroy_first);
    auto memory_size = sizeof(ValueType) * destroy_size;
    std::memset(memory_ptr, 0xab, memory_size);
#endif  // NDEBUG
  }
}

template <typename AllocatorType, typename ValueType, typename ValueAdapter,
          typename SizeType>
void ConstructElements(AllocatorType* alloc_ptr, ValueType* construct_first,
                       ValueAdapter* values_ptr, SizeType construct_size) {
  // If any construction fails, all completed constructions are rolled back.
  for (SizeType i = 0; i < construct_size; ++i) {
    ABSL_INTERNAL_TRY {
      values_ptr->ConstructNext(alloc_ptr, construct_first + i);
    }
    ABSL_INTERNAL_CATCH_ANY {
      inlined_vector_internal::DestroyElements(alloc_ptr, construct_first, i);

      ABSL_INTERNAL_RETHROW;
    }
  }
}

template <typename ValueType, typename ValueAdapter, typename SizeType>
void AssignElements(ValueType* assign_first, ValueAdapter* values_ptr,
                    SizeType assign_size) {
  for (SizeType i = 0; i < assign_size; ++i) {
    values_ptr->AssignNext(assign_first + i);
  }
}

template <typename AllocatorType>
struct StorageView {
  using pointer = typename AllocatorType::pointer;
  using size_type = typename AllocatorType::size_type;

  pointer data;
  size_type size;
  size_type capacity;
};

template <typename AllocatorType, typename Iterator>
class IteratorValueAdapter {
  using pointer = typename AllocatorType::pointer;
  using AllocatorTraits = absl::allocator_traits<AllocatorType>;

 public:
  explicit IteratorValueAdapter(const Iterator& it) : it_(it) {}

  void ConstructNext(AllocatorType* alloc_ptr, pointer construct_at) {
    AllocatorTraits::construct(*alloc_ptr, construct_at, *it_);
    ++it_;
  }

  void AssignNext(pointer assign_at) {
    *assign_at = *it_;
    ++it_;
  }

 private:
  Iterator it_;
};

template <typename AllocatorType>
class CopyValueAdapter {
  using pointer = typename AllocatorType::pointer;
  using const_pointer = typename AllocatorType::const_pointer;
  using const_reference = typename AllocatorType::const_reference;
  using AllocatorTraits = absl::allocator_traits<AllocatorType>;

 public:
  explicit CopyValueAdapter(const_reference v) : ptr_(std::addressof(v)) {}

  void ConstructNext(AllocatorType* alloc_ptr, pointer construct_at) {
    AllocatorTraits::construct(*alloc_ptr, construct_at, *ptr_);
  }

  void AssignNext(pointer assign_at) { *assign_at = *ptr_; }

 private:
  const_pointer ptr_;
};

template <typename AllocatorType>
class DefaultValueAdapter {
  using pointer = typename AllocatorType::pointer;
  using value_type = typename AllocatorType::value_type;
  using AllocatorTraits = absl::allocator_traits<AllocatorType>;

 public:
  explicit DefaultValueAdapter() {}

  void ConstructNext(AllocatorType* alloc_ptr, pointer construct_at) {
    AllocatorTraits::construct(*alloc_ptr, construct_at);
  }

  void AssignNext(pointer assign_at) { *assign_at = value_type(); }
};

template <typename AllocatorType>
class AllocationTransaction {
  using value_type = typename AllocatorType::value_type;
  using pointer = typename AllocatorType::pointer;
  using size_type = typename AllocatorType::size_type;
  using AllocatorTraits = absl::allocator_traits<AllocatorType>;

 public:
  explicit AllocationTransaction(AllocatorType* alloc_ptr)
      : alloc_data_(*alloc_ptr, nullptr) {}

  AllocationTransaction(const AllocationTransaction&) = delete;
  void operator=(const AllocationTransaction&) = delete;

  AllocatorType& GetAllocator() { return alloc_data_.template get<0>(); }
  pointer& GetData() { return alloc_data_.template get<1>(); }
  size_type& GetCapacity() { return capacity_; }

  bool DidAllocate() { return GetData() != nullptr; }
  pointer Allocate(size_type capacity) {
    GetData() = AllocatorTraits::allocate(GetAllocator(), capacity);
    GetCapacity() = capacity;
    return GetData();
  }

  ~AllocationTransaction() {
    if (DidAllocate()) {
      AllocatorTraits::deallocate(GetAllocator(), GetData(), GetCapacity());
    }
  }

 private:
  container_internal::CompressedTuple<AllocatorType, pointer> alloc_data_;
  size_type capacity_ = 0;
};

template <typename AllocatorType>
class ConstructionTransaction {
  using pointer = typename AllocatorType::pointer;
  using size_type = typename AllocatorType::size_type;

 public:
  explicit ConstructionTransaction(AllocatorType* alloc_ptr)
      : alloc_data_(*alloc_ptr, nullptr) {}

  ConstructionTransaction(const ConstructionTransaction&) = delete;
  void operator=(const ConstructionTransaction&) = delete;

  template <typename ValueAdapter>
  void Construct(pointer data, ValueAdapter* values_ptr, size_type size) {
    inlined_vector_internal::ConstructElements(std::addressof(GetAllocator()),
                                               data, values_ptr, size);
    GetData() = data;
    GetSize() = size;
  }
  void Commit() {
    GetData() = nullptr;
    GetSize() = 0;
  }

  ~ConstructionTransaction() {
    if (GetData() != nullptr) {
      inlined_vector_internal::DestroyElements(std::addressof(GetAllocator()),
                                               GetData(), GetSize());
    }
  }

 private:
  AllocatorType& GetAllocator() { return alloc_data_.template get<0>(); }
  pointer& GetData() { return alloc_data_.template get<1>(); }
  size_type& GetSize() { return size_; }

  container_internal::CompressedTuple<AllocatorType, pointer> alloc_data_;
  size_type size_ = 0;
};

template <typename T, size_t N, typename A>
class Storage {
 public:
  using allocator_type = A;
  using value_type = typename allocator_type::value_type;
  using pointer = typename allocator_type::pointer;
  using const_pointer = typename allocator_type::const_pointer;
  using reference = typename allocator_type::reference;
  using const_reference = typename allocator_type::const_reference;
  using rvalue_reference = typename allocator_type::value_type&&;
  using size_type = typename allocator_type::size_type;
  using difference_type = typename allocator_type::difference_type;
  using iterator = pointer;
  using const_iterator = const_pointer;
  using reverse_iterator = std::reverse_iterator<iterator>;
  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
  using MoveIterator = std::move_iterator<iterator>;
  using AllocatorTraits = absl::allocator_traits<allocator_type>;
  using IsMemcpyOk = inlined_vector_internal::IsMemcpyOk<allocator_type>;

  using StorageView = inlined_vector_internal::StorageView<allocator_type>;

  template <typename Iterator>
  using IteratorValueAdapter =
      inlined_vector_internal::IteratorValueAdapter<allocator_type, Iterator>;
  using CopyValueAdapter =
      inlined_vector_internal::CopyValueAdapter<allocator_type>;
  using DefaultValueAdapter =
      inlined_vector_internal::DefaultValueAdapter<allocator_type>;

  using AllocationTransaction =
      inlined_vector_internal::AllocationTransaction<allocator_type>;
  using ConstructionTransaction =
      inlined_vector_internal::ConstructionTransaction<allocator_type>;

  Storage() : metadata_() {}

  explicit Storage(const allocator_type& alloc)
      : metadata_(alloc, /* empty and inlined */ 0) {}

  ~Storage() {
    pointer data = GetIsAllocated() ? GetAllocatedData() : GetInlinedData();
    inlined_vector_internal::DestroyElements(GetAllocPtr(), data, GetSize());
    DeallocateIfAllocated();
  }

  size_type GetSize() const { return GetSizeAndIsAllocated() >> 1; }

  bool GetIsAllocated() const { return GetSizeAndIsAllocated() & 1; }

  pointer GetInlinedData() {
    return reinterpret_cast<pointer>(
        std::addressof(data_.inlined.inlined_data[0]));
  }

  const_pointer GetInlinedData() const {
    return reinterpret_cast<const_pointer>(
        std::addressof(data_.inlined.inlined_data[0]));
  }

  pointer GetAllocatedData() { return data_.allocated.allocated_data; }

  const_pointer GetAllocatedData() const {
    return data_.allocated.allocated_data;
  }

  size_type GetAllocatedCapacity() const {
    return data_.allocated.allocated_capacity;
  }

  StorageView MakeStorageView() {
    return GetIsAllocated() ? StorageView{GetAllocatedData(), GetSize(),
                                          GetAllocatedCapacity()}
                            : StorageView{GetInlinedData(), GetSize(),
                                          static_cast<size_type>(N)};
  }

  allocator_type* GetAllocPtr() {
    return std::addressof(metadata_.template get<0>());
  }

  const allocator_type* GetAllocPtr() const {
    return std::addressof(metadata_.template get<0>());
  }

  void SetIsAllocated() { GetSizeAndIsAllocated() |= 1; }

  void UnsetIsAllocated() {
    SetIsAllocated();
    GetSizeAndIsAllocated() -= 1;
  }

  void SetAllocatedSize(size_type size) {
    GetSizeAndIsAllocated() = (size << 1) | static_cast<size_type>(1);
  }

  void SetInlinedSize(size_type size) { GetSizeAndIsAllocated() = size << 1; }

  void SetSize(size_type size) {
    GetSizeAndIsAllocated() =
        (size << 1) | static_cast<size_type>(GetIsAllocated());
  }

  void AddSize(size_type count) { GetSizeAndIsAllocated() += count << 1; }

  void SubtractSize(size_type count) {
    assert(count <= GetSize());
    GetSizeAndIsAllocated() -= count << 1;
  }

  void SetAllocatedData(pointer data, size_type capacity) {
    data_.allocated.allocated_data = data;
    data_.allocated.allocated_capacity = capacity;
  }

  void DeallocateIfAllocated() {
    if (GetIsAllocated()) {
      AllocatorTraits::deallocate(*GetAllocPtr(), GetAllocatedData(),
                                  GetAllocatedCapacity());
    }
  }

  void AcquireAllocation(AllocationTransaction* allocation_tx_ptr) {
    SetAllocatedData(allocation_tx_ptr->GetData(),
                     allocation_tx_ptr->GetCapacity());
    allocation_tx_ptr->GetData() = nullptr;
    allocation_tx_ptr->GetCapacity() = 0;
  }

  void MemcpyFrom(const Storage& other_storage) {
    assert(IsMemcpyOk::value || other_storage.GetIsAllocated());

    GetSizeAndIsAllocated() = other_storage.GetSizeAndIsAllocated();
    data_ = other_storage.data_;
  }

  template <typename ValueAdapter>
  void Initialize(ValueAdapter values, size_type new_size);

  template <typename ValueAdapter>
  void Assign(ValueAdapter values, size_type new_size);

  template <typename ValueAdapter>
  void Resize(ValueAdapter values, size_type new_size);

  template <typename ValueAdapter>
  iterator Insert(const_iterator pos, ValueAdapter values,
                  size_type insert_count);

  template <typename... Args>
  reference EmplaceBack(Args&&... args);

  iterator Erase(const_iterator from, const_iterator to);

  void Reserve(size_type requested_capacity);

  void ShrinkToFit();

  void Swap(Storage* other_storage_ptr);

 private:
  size_type& GetSizeAndIsAllocated() { return metadata_.template get<1>(); }

  const size_type& GetSizeAndIsAllocated() const {
    return metadata_.template get<1>();
  }

  static size_type NextCapacityFrom(size_type current_capacity) {
    return current_capacity * 2;
  }

  static size_type LegacyNextCapacityFrom(size_type current_capacity,
                                          size_type requested_capacity) {
    // TODO(johnsoncj): Get rid of this old behavior.
    size_type new_capacity = current_capacity;
    while (new_capacity < requested_capacity) {
      new_capacity *= 2;
    }
    return new_capacity;
  }

  using Metadata =
      container_internal::CompressedTuple<allocator_type, size_type>;

  struct Allocated {
    pointer allocated_data;
    size_type allocated_capacity;
  };

  struct Inlined {
    using InlinedDataElement =
        absl::aligned_storage_t<sizeof(value_type), alignof(value_type)>;
    InlinedDataElement inlined_data[N];
  };

  union Data {
    Allocated allocated;
    Inlined inlined;
  };

  Metadata metadata_;
  Data data_;
};

template <typename T, size_t N, typename A>
template <typename ValueAdapter>
auto Storage<T, N, A>::Initialize(ValueAdapter values, size_type new_size)
    -> void {
  // Only callable from constructors!
  assert(!GetIsAllocated());
  assert(GetSize() == 0);

  pointer construct_data;

  if (new_size > static_cast<size_type>(N)) {
    // Because this is only called from the `InlinedVector` constructors, it's
    // safe to take on the allocation with size `0`. If `ConstructElements(...)`
    // throws, deallocation will be automatically handled by `~Storage()`.
    construct_data = AllocatorTraits::allocate(*GetAllocPtr(), new_size);
    SetAllocatedData(construct_data, new_size);
    SetIsAllocated();
  } else {
    construct_data = GetInlinedData();
  }

  inlined_vector_internal::ConstructElements(GetAllocPtr(), construct_data,
                                             &values, new_size);

  // Since the initial size was guaranteed to be `0` and the allocated bit is
  // already correct for either case, *adding* `new_size` gives us the correct
  // result faster than setting it directly.
  AddSize(new_size);
}

template <typename T, size_t N, typename A>
template <typename ValueAdapter>
auto Storage<T, N, A>::Assign(ValueAdapter values, size_type new_size) -> void {
  StorageView storage_view = MakeStorageView();

  AllocationTransaction allocation_tx(GetAllocPtr());

  absl::Span<value_type> assign_loop;
  absl::Span<value_type> construct_loop;
  absl::Span<value_type> destroy_loop;

  if (new_size > storage_view.capacity) {
    construct_loop = {allocation_tx.Allocate(new_size), new_size};
    destroy_loop = {storage_view.data, storage_view.size};
  } else if (new_size > storage_view.size) {
    assign_loop = {storage_view.data, storage_view.size};
    construct_loop = {storage_view.data + storage_view.size,
                      new_size - storage_view.size};
  } else {
    assign_loop = {storage_view.data, new_size};
    destroy_loop = {storage_view.data + new_size, storage_view.size - new_size};
  }

  inlined_vector_internal::AssignElements(assign_loop.data(), &values,
                                          assign_loop.size());

  inlined_vector_internal::ConstructElements(
      GetAllocPtr(), construct_loop.data(), &values, construct_loop.size());

  inlined_vector_internal::DestroyElements(GetAllocPtr(), destroy_loop.data(),
                                           destroy_loop.size());

  if (allocation_tx.DidAllocate()) {
    DeallocateIfAllocated();
    AcquireAllocation(&allocation_tx);
    SetIsAllocated();
  }

  SetSize(new_size);
}

template <typename T, size_t N, typename A>
template <typename ValueAdapter>
auto Storage<T, N, A>::Resize(ValueAdapter values, size_type new_size) -> void {
  StorageView storage_view = MakeStorageView();

  AllocationTransaction allocation_tx(GetAllocPtr());
  ConstructionTransaction construction_tx(GetAllocPtr());

  IteratorValueAdapter<MoveIterator> move_values(
      MoveIterator(storage_view.data));

  absl::Span<value_type> construct_loop;
  absl::Span<value_type> move_construct_loop;
  absl::Span<value_type> destroy_loop;

  if (new_size > storage_view.capacity) {
    pointer new_data = allocation_tx.Allocate(
        LegacyNextCapacityFrom(storage_view.capacity, new_size));

    // Construct new objects in `new_data`
    construct_loop = {new_data + storage_view.size,
                      new_size - storage_view.size};

    // Move all existing objects into `new_data`
    move_construct_loop = {new_data, storage_view.size};

    // Destroy all existing objects in `storage_view.data`
    destroy_loop = {storage_view.data, storage_view.size};
  } else if (new_size > storage_view.size) {
    // Construct new objects in `storage_view.data`
    construct_loop = {storage_view.data + storage_view.size,
                      new_size - storage_view.size};
  } else {
    // Destroy end `storage_view.size - new_size` objects in `storage_view.data`
    destroy_loop = {storage_view.data + new_size, storage_view.size - new_size};
  }

  construction_tx.Construct(construct_loop.data(), &values,
                            construct_loop.size());

  inlined_vector_internal::ConstructElements(
      GetAllocPtr(), move_construct_loop.data(), &move_values,
      move_construct_loop.size());

  inlined_vector_internal::DestroyElements(GetAllocPtr(), destroy_loop.data(),
                                           destroy_loop.size());

  construction_tx.Commit();
  if (allocation_tx.DidAllocate()) {
    DeallocateIfAllocated();
    AcquireAllocation(&allocation_tx);
    SetIsAllocated();
  }

  SetSize(new_size);
}

template <typename T, size_t N, typename A>
template <typename ValueAdapter>
auto Storage<T, N, A>::Insert(const_iterator pos, ValueAdapter values,
                              size_type insert_count) -> iterator {
  StorageView storage_view = MakeStorageView();

  size_type insert_index =
      std::distance(const_iterator(storage_view.data), pos);
  size_type insert_end_index = insert_index + insert_count;
  size_type new_size = storage_view.size + insert_count;

  if (new_size > storage_view.capacity) {
    AllocationTransaction allocation_tx(GetAllocPtr());
    ConstructionTransaction construction_tx(GetAllocPtr());
    ConstructionTransaction move_construciton_tx(GetAllocPtr());

    IteratorValueAdapter<MoveIterator> move_values(
        MoveIterator(storage_view.data));

    pointer new_data = allocation_tx.Allocate(
        LegacyNextCapacityFrom(storage_view.capacity, new_size));

    construction_tx.Construct(new_data + insert_index, &values, insert_count);

    move_construciton_tx.Construct(new_data, &move_values, insert_index);

    inlined_vector_internal::ConstructElements(
        GetAllocPtr(), new_data + insert_end_index, &move_values,
        storage_view.size - insert_index);

    inlined_vector_internal::DestroyElements(GetAllocPtr(), storage_view.data,
                                             storage_view.size);

    construction_tx.Commit();
    move_construciton_tx.Commit();
    DeallocateIfAllocated();
    AcquireAllocation(&allocation_tx);

    SetAllocatedSize(new_size);
    return iterator(new_data + insert_index);
  } else {
    size_type move_construction_destination_index =
        (std::max)(insert_end_index, storage_view.size);

    ConstructionTransaction move_construction_tx(GetAllocPtr());

    IteratorValueAdapter<MoveIterator> move_construction_values(
        MoveIterator(storage_view.data +
                     (move_construction_destination_index - insert_count)));
    absl::Span<value_type> move_construction = {
        storage_view.data + move_construction_destination_index,
        new_size - move_construction_destination_index};

    pointer move_assignment_values = storage_view.data + insert_index;
    absl::Span<value_type> move_assignment = {
        storage_view.data + insert_end_index,
        move_construction_destination_index - insert_end_index};

    absl::Span<value_type> insert_assignment = {move_assignment_values,
                                                move_construction.size()};

    absl::Span<value_type> insert_construction = {
        insert_assignment.data() + insert_assignment.size(),
        insert_count - insert_assignment.size()};

    move_construction_tx.Construct(move_construction.data(),
                                   &move_construction_values,
                                   move_construction.size());

    for (pointer destination = move_assignment.data() + move_assignment.size(),
                 last_destination = move_assignment.data(),
                 source = move_assignment_values + move_assignment.size();
         ;) {
      --destination;
      --source;
      if (destination < last_destination) break;
      *destination = std::move(*source);
    }

    inlined_vector_internal::AssignElements(insert_assignment.data(), &values,
                                            insert_assignment.size());

    inlined_vector_internal::ConstructElements(
        GetAllocPtr(), insert_construction.data(), &values,
        insert_construction.size());

    move_construction_tx.Commit();

    AddSize(insert_count);
    return iterator(storage_view.data + insert_index);
  }
}

template <typename T, size_t N, typename A>
template <typename... Args>
auto Storage<T, N, A>::EmplaceBack(Args&&... args) -> reference {
  StorageView storage_view = MakeStorageView();

  AllocationTransaction allocation_tx(GetAllocPtr());

  IteratorValueAdapter<MoveIterator> move_values(
      MoveIterator(storage_view.data));

  pointer construct_data =
      (storage_view.size == storage_view.capacity
           ? allocation_tx.Allocate(NextCapacityFrom(storage_view.capacity))
           : storage_view.data);

  pointer last_ptr = construct_data + storage_view.size;
  AllocatorTraits::construct(*GetAllocPtr(), last_ptr,
                             std::forward<Args>(args)...);

  if (allocation_tx.DidAllocate()) {
    ABSL_INTERNAL_TRY {
      inlined_vector_internal::ConstructElements(
          GetAllocPtr(), allocation_tx.GetData(), &move_values,
          storage_view.size);
    }
    ABSL_INTERNAL_CATCH_ANY {
      AllocatorTraits::destroy(*GetAllocPtr(), last_ptr);
      ABSL_INTERNAL_RETHROW;
    }

    inlined_vector_internal::DestroyElements(GetAllocPtr(), storage_view.data,
                                             storage_view.size);

    DeallocateIfAllocated();
    AcquireAllocation(&allocation_tx);
    SetIsAllocated();
  }

  AddSize(1);
  return *last_ptr;
}

template <typename T, size_t N, typename A>
auto Storage<T, N, A>::Erase(const_iterator from, const_iterator to)
    -> iterator {
  assert(from != to);

  StorageView storage_view = MakeStorageView();

  size_type erase_size = std::distance(from, to);
  size_type erase_index =
      std::distance(const_iterator(storage_view.data), from);
  size_type erase_end_index = erase_index + erase_size;

  IteratorValueAdapter<MoveIterator> move_values(
      MoveIterator(storage_view.data + erase_end_index));

  inlined_vector_internal::AssignElements(storage_view.data + erase_index,
                                          &move_values,
                                          storage_view.size - erase_end_index);

  inlined_vector_internal::DestroyElements(
      GetAllocPtr(), storage_view.data + (storage_view.size - erase_size),
      erase_size);

  SubtractSize(erase_size);
  return iterator(storage_view.data + erase_index);
}

template <typename T, size_t N, typename A>
auto Storage<T, N, A>::Reserve(size_type requested_capacity) -> void {
  StorageView storage_view = MakeStorageView();

  if (ABSL_PREDICT_FALSE(requested_capacity <= storage_view.capacity)) return;

  AllocationTransaction allocation_tx(GetAllocPtr());

  IteratorValueAdapter<MoveIterator> move_values(
      MoveIterator(storage_view.data));

  pointer new_data = allocation_tx.Allocate(
      LegacyNextCapacityFrom(storage_view.capacity, requested_capacity));

  inlined_vector_internal::ConstructElements(GetAllocPtr(), new_data,
                                             &move_values, storage_view.size);

  inlined_vector_internal::DestroyElements(GetAllocPtr(), storage_view.data,
                                           storage_view.size);

  DeallocateIfAllocated();
  AcquireAllocation(&allocation_tx);
  SetIsAllocated();
}

template <typename T, size_t N, typename A>
auto Storage<T, N, A>::ShrinkToFit() -> void {
  // May only be called on allocated instances!
  assert(GetIsAllocated());

  StorageView storage_view{GetAllocatedData(), GetSize(),
                           GetAllocatedCapacity()};

  AllocationTransaction allocation_tx(GetAllocPtr());

  IteratorValueAdapter<MoveIterator> move_values(
      MoveIterator(storage_view.data));

  pointer construct_data;

  if (storage_view.size <= static_cast<size_type>(N)) {
    construct_data = GetInlinedData();
  } else if (storage_view.size < GetAllocatedCapacity()) {
    construct_data = allocation_tx.Allocate(storage_view.size);
  } else {
    return;
  }

  ABSL_INTERNAL_TRY {
    inlined_vector_internal::ConstructElements(GetAllocPtr(), construct_data,
                                               &move_values, storage_view.size);
  }
  ABSL_INTERNAL_CATCH_ANY {
    // Writing to inlined data will trample on the existing state, thus it needs
    // to be restored when a construction fails.
    SetAllocatedData(storage_view.data, storage_view.capacity);
    ABSL_INTERNAL_RETHROW;
  }

  inlined_vector_internal::DestroyElements(GetAllocPtr(), storage_view.data,
                                           storage_view.size);

  AllocatorTraits::deallocate(*GetAllocPtr(), storage_view.data,
                              storage_view.capacity);

  if (allocation_tx.DidAllocate()) {
    AcquireAllocation(&allocation_tx);
  } else {
    UnsetIsAllocated();
  }
}

template <typename T, size_t N, typename A>
auto Storage<T, N, A>::Swap(Storage* other_storage_ptr) -> void {
  using std::swap;
  assert(this != other_storage_ptr);

  if (GetIsAllocated() && other_storage_ptr->GetIsAllocated()) {
    // Both are allocated, thus we can swap the allocations at the top level.

    swap(data_.allocated, other_storage_ptr->data_.allocated);
  } else if (!GetIsAllocated() && !other_storage_ptr->GetIsAllocated()) {
    // Both are inlined, thus element-wise swap up to smaller size, then move
    // the remaining elements.

    Storage* small_ptr = this;
    Storage* large_ptr = other_storage_ptr;
    if (small_ptr->GetSize() > large_ptr->GetSize()) swap(small_ptr, large_ptr);

    for (size_type i = 0; i < small_ptr->GetSize(); ++i) {
      swap(small_ptr->GetInlinedData()[i], large_ptr->GetInlinedData()[i]);
    }

    IteratorValueAdapter<MoveIterator> move_values(
        MoveIterator(large_ptr->GetInlinedData() + small_ptr->GetSize()));

    inlined_vector_internal::ConstructElements(
        large_ptr->GetAllocPtr(),
        small_ptr->GetInlinedData() + small_ptr->GetSize(), &move_values,
        large_ptr->GetSize() - small_ptr->GetSize());

    inlined_vector_internal::DestroyElements(
        large_ptr->GetAllocPtr(),
        large_ptr->GetInlinedData() + small_ptr->GetSize(),
        large_ptr->GetSize() - small_ptr->GetSize());
  } else {
    // One is allocated and the other is inlined, thus we first move the
    // elements from the inlined instance to the inlined space in the allocated
    // instance and then we can finish by having the other vector take on the
    // allocation.

    Storage* allocated_ptr = this;
    Storage* inlined_ptr = other_storage_ptr;
    if (!allocated_ptr->GetIsAllocated()) swap(allocated_ptr, inlined_ptr);

    StorageView allocated_storage_view{allocated_ptr->GetAllocatedData(),
                                       allocated_ptr->GetSize(),
                                       allocated_ptr->GetAllocatedCapacity()};

    IteratorValueAdapter<MoveIterator> move_values(
        MoveIterator(inlined_ptr->GetInlinedData()));

    ABSL_INTERNAL_TRY {
      inlined_vector_internal::ConstructElements(
          inlined_ptr->GetAllocPtr(), allocated_ptr->GetInlinedData(),
          &move_values, inlined_ptr->GetSize());
    }
    ABSL_INTERNAL_CATCH_ANY {
      // Writing to inlined data will trample on the existing state, thus it
      // needs to be restored when a construction fails.
      allocated_ptr->SetAllocatedData(allocated_storage_view.data,
                                      allocated_storage_view.capacity);
      ABSL_INTERNAL_RETHROW;
    }

    inlined_vector_internal::DestroyElements(inlined_ptr->GetAllocPtr(),
                                             inlined_ptr->GetInlinedData(),
                                             inlined_ptr->GetSize());

    inlined_ptr->SetAllocatedData(allocated_storage_view.data,
                                  allocated_storage_view.capacity);
  }

  // All cases swap the size, `is_allocated` boolean and the allocator.
  swap(GetSizeAndIsAllocated(), other_storage_ptr->GetSizeAndIsAllocated());
  swap(*GetAllocPtr(), *other_storage_ptr->GetAllocPtr());
}

}  // namespace inlined_vector_internal
}  // namespace absl

#endif  // ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_