summaryrefslogtreecommitdiff
path: root/absl/container/internal/inlined_vector.h
blob: 4589ce0837a408c72b35450111d2ffc90746ddbd (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
// 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/container/internal/compressed_tuple.h"
#include "absl/meta/type_traits.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, typename ValueType, typename SizeType>
void DestroyElements(AllocatorType alloc, ValueType* destroy_first,
                     SizeType destroy_size) {
  using AllocatorTraits = std::allocator_traits<AllocatorType>;

  // Destroys `destroy_size` elements from `destroy_first`.
  //
  // Destroys the range
  //   [`destroy_first`, `destroy_first + destroy_size`).
  //
  // NOTE: We assume destructors do not throw and thus make no attempt to roll
  // back.
  for (SizeType i = 0; i < destroy_size; ++i) {
    AllocatorTraits::destroy(alloc, 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.
  void* memory = reinterpret_cast<void*>(destroy_first);
  size_t memory_size = sizeof(ValueType) * destroy_size;
  std::memset(memory, 0xab, memory_size);
#endif  // NDEBUG
}

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 AllocatorTraits = std::allocator_traits<allocator_type>;

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

  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;
  }

  allocator_type& GetAllocator() { return metadata_.template get<0>(); }

  const allocator_type& GetAllocator() const {
    return metadata_.template get<0>();
  }

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

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

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

  void SetAllocatedData(pointer data) { data_.allocated.allocated_data = data; }

  void SetAllocatedCapacity(size_type capacity) {
    data_.allocated.allocated_capacity = capacity;
  }

  void SwapSizeAndIsAllocated(Storage* other) {
    using std::swap;
    swap(GetSizeAndIsAllocated(), other->GetSizeAndIsAllocated());
  }

  void SwapAllocatedSizeAndCapacity(Storage* other) {
    using std::swap;
    swap(data_.allocated, other->data_.allocated);
  }

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

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

  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_;
};

}  // namespace inlined_vector_internal
}  // namespace absl

#endif  // ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_