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/*
* 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 };
};
}
#if USING_AK_GLOBALLY
using AK::FixedArray;
#endif
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