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// SPDX-License-Identifier: CC0-1.0
#pragma once
#include <array>
#include <cassert>
#include <cstddef>
#include <utility>
namespace Common
{
// An std::vector-like container that uses no heap allocations but is limited to a maximum size.
template <typename T, size_t MaxSize>
class SmallVector final
{
public:
using value_type = T;
SmallVector() = default;
explicit SmallVector(size_t new_size) { resize(new_size); }
~SmallVector() { clear(); }
SmallVector(const SmallVector& other)
{
for (auto& value : other)
emplace_back(value);
}
SmallVector& operator=(const SmallVector& rhs)
{
clear();
for (auto& value : rhs)
emplace_back(value);
return *this;
}
SmallVector(SmallVector&& other)
{
for (auto& value : other)
emplace_back(std::move(value));
other.clear();
}
SmallVector& operator=(SmallVector&& rhs)
{
clear();
for (auto& value : rhs)
emplace_back(std::move(value));
rhs.clear();
return *this;
}
void push_back(const value_type& x) { emplace_back(x); }
void push_back(value_type&& x) { emplace_back(std::move(x)); }
template <typename... Args>
value_type& emplace_back(Args&&... args)
{
assert(m_size < MaxSize);
return *::new (&m_array[m_size++ * sizeof(value_type)]) value_type{std::forward<Args>(args)...};
}
void pop_back()
{
assert(m_size > 0);
std::destroy_at(data() + --m_size);
}
value_type& operator[](size_t i)
{
assert(i < m_size);
return data()[i];
}
const value_type& operator[](size_t i) const
{
assert(i < m_size);
return data()[i];
}
auto data() { return std::launder(reinterpret_cast<value_type*>(m_array.data())); }
auto begin() { return data(); }
auto end() { return data() + m_size; }
auto data() const { return std::launder(reinterpret_cast<const value_type*>(m_array.data())); }
auto begin() const { return data(); }
auto end() const { return data() + m_size; }
size_t capacity() const { return MaxSize; }
size_t size() const { return m_size; }
bool empty() const { return m_size == 0; }
void resize(size_t new_size)
{
assert(new_size <= MaxSize);
while (size() < new_size)
emplace_back();
while (size() > new_size)
pop_back();
}
void clear() { resize(0); }
private:
alignas(value_type) std::array<std::byte, MaxSize * sizeof(value_type)> m_array;
size_t m_size = 0;
};
} // namespace Common
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