AllocatorTwoInOne

#include <vector>
#include <stack>

class FixedAllocator {
 public:
  FixedAllocator(size_t chunk_size, size_t page_size);
  void *Allocate();
  void Deallocate(void *value);

 private:
  size_t chunk_size;
  size_t page_size;
  std::vector<std::vector<unsigned char>> pool;
  std::stack<unsigned char*> free_memory;
};

FixedAllocator::FixedAllocator(size_t chunk_size, size_t page_size) {
  this->chunk_size = chunk_size;
  this->page_size = page_size;
}

void *FixedAllocator::Allocate() {
  if (free_memory.empty()) {
    pool.emplace_back(page_size * chunk_size);
    for (size_t i = 0; i < page_size * chunk_size; i += chunk_size)
      free_memory.push(&pool.back()[i]);
  }
  auto top_memory = free_memory.top();
  free_memory.pop();
  return top_memory;
}

void FixedAllocator::Deallocate(void *value) {
  auto del_memory = static_cast<unsigned char *>(value);
  free_memory.push(del_memory);
}