ardupilot/libraries/AP_HAL/utility/OwnPtr.h

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* Copyright (C) 2015-2016 Intel Corporation. All rights reserved.
*
* This file is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This file is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <cstddef>
namespace AP_HAL {
/* Poor's man std::unique_ptr
*
* OwnPtr is a container for a pointer declaring ownership.
*
* The goal is to allow to own object, pass it around and automatically delete
* the pointer when the container goes out of scope.
*
* In order to pass it around the move constructor or move assignment operator
* must be used. operator*, operator-> and the get() method can be used to get
* the pointer contained in the OwnPtr container.
*
* The OwnPtr name comes from similar class in WebKit, before they switched to
* std::unique_ptr. The implementation is different/simpler. We need our own
* implementation since the <memory> header (and thus std::unique_ptr) is not
* compatible with the PX4 toolchain and/or nuttx headers.
*/
template<typename T>
class OwnPtr {
public:
OwnPtr() : _ptr(nullptr) { }
OwnPtr(std::nullptr_t) : _ptr(nullptr) { }
/* non-copyable */
OwnPtr(const OwnPtr<T> &other) = delete;
/* Allow construction from a derived class U */
template<typename U>
OwnPtr(OwnPtr<U>&& other) : _ptr(other.leak()) { }
OwnPtr(T *ptr) : _ptr(ptr) { }
OwnPtr<T>& operator=(std::nullptr_t) { clear(); return *this; }
template<typename U>
OwnPtr<T>& operator=(OwnPtr<U>&& other)
{
T *old = _ptr;
_ptr = other.leak();
delete old;
return *this;
}
template<typename U>
OwnPtr<T>& operator=(U *other)
{
T *old = _ptr;
_ptr = other;
delete old;
return *this;
}
~OwnPtr() { delete _ptr; }
void clear()
{
delete leak();
}
T *leak()
{
T *old = _ptr;
_ptr = nullptr;
return old;
}
T *get() const
{
return _ptr;
}
T& operator*() const { return *_ptr; }
T *operator->() const { return _ptr; }
bool operator !() const { return !_ptr; }
explicit operator bool() const { return _ptr != nullptr; }
private:
T *_ptr;
};
template<typename T>
inline bool operator==(T* a, const OwnPtr<T>& b)
{
return a == b.get();
}
template<typename T>
inline bool operator==(const OwnPtr<T>& a, T* b)
{
return a.get() == b;
}
template<typename T>
inline bool operator!=(T* a, const OwnPtr<T>& b)
{
return a != b.get();
}
template<typename T>
inline bool operator!=(const OwnPtr<T>& a, T* b)
{
return a.get() != b;
}
}