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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>
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(size_t size)
{
if (size == 0)
return FixedArray<T>();
T* elements = static_cast<T*>(kmalloc_array(size, sizeof(T)));
if (!elements)
return Error::from_errno(ENOMEM);
for (size_t i = 0; i < size; ++i)
new (&elements[i]) T();
return FixedArray<T>(size, elements);
}
static FixedArray<T> must_create_but_fixme_should_propagate_errors(size_t size)
{
return MUST(try_create(size));
}
// NOTE:
// Even though it may look like there will be a template instantiation of this function for every size,
// the compiler will inline this anyway and therefore not generate any duplicate code.
template<size_t N>
static ErrorOr<FixedArray<T>> try_create(T(&&array)[N])
{
if (N == 0)
return FixedArray<T>();
T* elements = static_cast<T*>(kmalloc_array(N, sizeof(T)));
if (!elements)
return Error::from_errno(ENOMEM);
for (size_t i = 0; i < N; ++i)
new (&elements[i]) T(move(array[i]));
return FixedArray<T>(N, elements);
}
template<typename U>
static ErrorOr<FixedArray<T>> try_create(Span<U> span)
{
if (span.size() == 0)
return FixedArray<T>();
T* elements = static_cast<T*>(kmalloc_array(span.size(), sizeof(T)));
if (!elements)
return Error::from_errno(ENOMEM);
for (size_t i = 0; i < span.size(); ++i)
new (&elements[i]) T(span[i]);
return FixedArray<T>(span.size(), elements);
}
ErrorOr<FixedArray<T>> try_clone() const
{
if (m_size == 0)
return FixedArray<T>();
T* elements = static_cast<T*>(kmalloc_array(m_size, sizeof(T)));
if (!elements)
return Error::from_errno(ENOMEM);
for (size_t i = 0; i < m_size; ++i)
new (&elements[i]) T(m_elements[i]);
return FixedArray<T>(m_size, elements);
}
FixedArray<T> must_clone_but_fixme_should_propagate_errors() const
{
return MUST(try_clone());
}
// 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_size(other.m_size)
, m_elements(other.m_elements)
{
other.m_size = 0;
other.m_elements = 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_elements)
return;
for (size_t i = 0; i < m_size; ++i)
m_elements[i].~T();
kfree_sized(m_elements, sizeof(T) * m_size);
// NOTE: should prevent use-after-free early
m_size = 0;
m_elements = nullptr;
}
size_t size() const { return m_size; }
T* data() { return m_elements; }
T const* data() const { return m_elements; }
T& operator[](size_t index)
{
VERIFY(index < m_size);
return m_elements[index];
}
T const& operator[](size_t index) const
{
VERIFY(index < m_size);
return m_elements[index];
}
bool contains_slow(T const& value) const
{
for (size_t i = 0; i < m_size; ++i) {
if (m_elements[i] == value)
return true;
}
return false;
}
void swap(FixedArray<T>& other)
{
::swap(m_size, other.m_size);
::swap(m_elements, other.m_elements);
}
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:
FixedArray(size_t size, T* elements)
: m_size(size)
, m_elements(elements)
{
}
size_t m_size { 0 };
T* m_elements { nullptr };
};
}
using AK::FixedArray;
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