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#pragma once
#include <vector>
template <typename T>
class MemoryHeap
{
public:
using Index = std::size_t;
using Indices = std::vector<Index>;
MemoryHeap() = default;
MemoryHeap(std::size_t size)
{
memory.reserve(size);
free_indices.reserve(size);
}
template <typename... Args>
Index emplace(Args&&... args);
Index add(const T& element);
T& get(Index index);
const T& get(Index index) const;
void remove(Index index);
private:
std::vector<T> memory;
Indices free_indices;
};
template <typename T>
auto MemoryHeap<T>::add(const T& element) -> Index
{
if (free_indices.empty())
{
memory.push_back(element);
return memory.size()-1;
}
auto free_index = free_indices.back();
free_indices.pop_back();
memory[free_index] = element;
return free_index;
}
template <typename T>
template <typename... Args>
auto MemoryHeap<T>::emplace(Args&&... args) -> Index
{
if (free_indices.empty())
{
memory.emplace_back(std::forward<Args>(args)...);
return memory.size()-1;
}
auto free_index = free_indices.back();
free_indices.pop_back();
memory[free_index] = T(std::forward<Args>(args)...);
return free_index;
}
template <typename T>
T& MemoryHeap<T>::get(Index index)
{
assert(index < memory.size());
return memory[index];
}
template <typename T>
const T& MemoryHeap<T>::get(Index index) const
{
assert(index < memory.size());
return memory[index];
}
template <typename T>
void MemoryHeap<T>::remove(Index index)
{
free_indices.push_back(index);
}
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