static_container

// vi:set ft=cpp: -*- Mode: C++ -*-
 
/* SPDX-License-Identifier: GPL-2.0-only or License-Ref-kk-custom */
/*
 * Copyright (C) 2012-2013 Technische Universität Dresden.
 * Copyright (C) 2016-2017, 2020 Kernkonzept GmbH.
 */
 
#pragma once
 
#include <l4/cxx/type_traits>
#include <stddef.h>
 
namespace cxx {
 
template< typename T >
class Static_container
{
private:
  struct X : T
  {
    void *operator new (size_t, void *p) noexcept { return p; }
    void operator delete (void *) {}
    X() = default;
    template<typename ...Args>
    X(Args && ...a) : T(cxx::forward<Args>(a)...) {}
  };
 
public:
  void operator = (Static_container const &) = delete;
  Static_container(Static_container const &) = delete;
  Static_container() = default;
 
  T *get() { return reinterpret_cast<X*>(_s); }
  T *operator -> () { return get(); }
  T &operator * () { return *get(); }
  operator T* () { return get(); }
 
  void construct()
  { new (reinterpret_cast<void*>(_s)) X; }
 
  template< typename ...Args >
  void construct(Args && ...args)
  { new (reinterpret_cast<void*>(_s)) X(cxx::forward<Args>(args)...); }
 
private:
  char _s[sizeof(X)] __attribute__((aligned(__alignof(X))));
};
 
}