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
|
/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Error.h>
#include <AK/Iterator.h>
#include <AK/Span.h>
#include <AK/kmalloc.h>
#include <initializer_list>
namespace AK {
// FixedArray is an Array with a size only known at run-time.
// It guarantees to only allocate when being constructed, and to only deallocate when being destructed.
template<typename T>
class FixedArray {
public:
FixedArray() = default;
static ErrorOr<FixedArray<T>> try_create(std::initializer_list<T> initializer)
{
auto array = TRY(try_create(initializer.size()));
auto it = initializer.begin();
for (size_t i = 0; i < array.size(); ++i) {
array[i] = move(*it);
++it;
}
return array;
}
static ErrorOr<FixedArray<T>> try_create(size_t size)
{
if (size == 0)
return FixedArray<T>();
auto* new_storage = static_cast<Storage*>(kmalloc(storage_allocation_size(size)));
if (!new_storage)
return Error::from_errno(ENOMEM);
new_storage->size = size;
for (size_t i = 0; i < size; ++i)
new (&new_storage->elements[i]) T();
return FixedArray<T>(new_storage);
}
static FixedArray<T> must_create_but_fixme_should_propagate_errors(size_t size)
{
return MUST(try_create(size));
}
template<size_t N>
static ErrorOr<FixedArray<T>> try_create(T (&&array)[N])
{
return try_create(Span(array, N));
}
template<typename U>
static ErrorOr<FixedArray<T>> try_create(Span<U> span)
{
if (span.size() == 0)
return FixedArray<T>();
auto* new_storage = static_cast<Storage*>(kmalloc(storage_allocation_size(span.size())));
if (!new_storage)
return Error::from_errno(ENOMEM);
new_storage->size = span.size();
for (size_t i = 0; i < span.size(); ++i)
new (&new_storage->elements[i]) T(span[i]);
return FixedArray<T>(new_storage);
}
ErrorOr<FixedArray<T>> try_clone() const
{
return try_create(span());
}
static size_t storage_allocation_size(size_t size)
{
return sizeof(Storage) + size * sizeof(T);
}
// Nobody can ever use these functions, since it would be impossible to make them OOM-safe due to their signatures. We just explicitly delete them.
FixedArray(FixedArray<T> const&) = delete;
FixedArray<T>& operator=(FixedArray<T> const&) = delete;
FixedArray(FixedArray<T>&& other)
: m_storage(exchange(other.m_storage, nullptr))
{
}
// This function would violate the contract, as it would need to deallocate this FixedArray. As it also has no use case, we delete it.
FixedArray<T>& operator=(FixedArray<T>&&) = delete;
~FixedArray()
{
if (!m_storage)
return;
for (size_t i = 0; i < m_storage->size; ++i)
m_storage->elements[i].~T();
kfree_sized(m_storage, storage_allocation_size(m_storage->size));
m_storage = nullptr;
}
size_t size() const { return m_storage ? m_storage->size : 0; }
bool is_empty() const { return size() == 0; }
T* data() { return m_storage ? m_storage->elements : nullptr; }
T const* data() const { return m_storage ? m_storage->elements : nullptr; }
T& at(size_t index)
{
VERIFY(index < m_storage->size);
return m_storage->elements[index];
}
T const& at(size_t index) const
{
VERIFY(index < m_storage->size);
return m_storage->elements[index];
}
T& operator[](size_t index)
{
return at(index);
}
T const& operator[](size_t index) const
{
return at(index);
}
bool contains_slow(T const& value) const
{
if (!m_storage)
return false;
for (size_t i = 0; i < m_storage->size; ++i) {
if (m_storage->elements[i] == value)
return true;
}
return false;
}
void swap(FixedArray<T>& other)
{
::swap(m_storage, other.m_storage);
}
void fill_with(T const& value)
{
if (!m_storage)
return;
for (size_t i = 0; i < m_storage->size; ++i)
m_storage->elements[i] = value;
}
using Iterator = SimpleIterator<FixedArray, T>;
using ConstIterator = SimpleIterator<FixedArray const, T const>;
Iterator begin() { return Iterator::begin(*this); }
ConstIterator begin() const { return ConstIterator::begin(*this); }
Iterator end() { return Iterator::end(*this); }
ConstIterator end() const { return ConstIterator::end(*this); }
Span<T> span() { return { data(), size() }; }
Span<T const> span() const { return { data(), size() }; }
private:
struct Storage {
size_t size { 0 };
T elements[0];
};
FixedArray(Storage* storage)
: m_storage(storage)
{
}
Storage* m_storage { nullptr };
};
}
using AK::FixedArray;
|
