stack_allocator.hpp

/**************************************************************************/
/* stack_allocator.hpp                                                    */
/**************************************************************************/
/*                         This file is part of:                          */
/*                                Knoodle                                 */
/*                        https://knoodlegraph.org                        */
/**************************************************************************/
/* Copyright (c) 2025 Knoodle contributors (vide AUTHORS.md)              */
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#pragma once
 
#include <stdlib.h>
#include <cstddef>
#include <memory>
#include "common.hpp"
#include "core_api.hpp"
#include "kn_assert.hpp"
 
namespace kn {
class KN_CORE_API StackAllocator {
 public:
  StackAllocator() = default;
  StackAllocator(const StackAllocator&) = delete;
  StackAllocator& operator=(const StackAllocator&) = delete;
 
  ~StackAllocator();
 
  void initialize(size_t size);
 
  void* allocate(std::size_t size, std::size_t alignment = alignof(std::max_align_t)) {
    std::size_t space = static_cast<char*>(_end) - static_cast<char*>(_current);
    void* alignedPtr = _current;
 
    if (std::align(alignment, size, alignedPtr, space)) {
      _current = static_cast<char*>(alignedPtr) + size;
      return alignedPtr;
    }
 
    return nullptr;
  }
 
  void deallocate(void* ptr) {
    assert(ptr < _current);
    _current = ptr;
  }
 
  [[nodiscard]] inline size_t get_size() const {
    return reinterpret_cast<uintptr_t>(_end) - reinterpret_cast<uintptr_t>(_start);
  }
 
 private:
  void* _start{nullptr};
  void* _end{nullptr};
  void* _current{nullptr};
};
}  // namespace kn