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/*
Minetest
Copyright (C) 2018 numzero, Lobachevskiy Vitaliy <numzer0@yandex.ru>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include <type_traits>
#include "irrlichttypes.h"
#include "IReferenceCounted.h"
/** Shared pointer for IrrLicht objects.
*
* It should only be used for user-managed objects, i.e. those created with
* the @c new operator or @c create* functions, like:
* `irr_ptr<scene::IMeshBuffer> buf{new scene::SMeshBuffer()};`
*
* It should *never* be used for engine-managed objects, including
* those created with @c addTexture and similar methods.
*/
template <class ReferenceCounted,
class = typename std::enable_if<std::is_base_of<IReferenceCounted,
ReferenceCounted>::value>::type>
class irr_ptr
{
ReferenceCounted *value = nullptr;
/** Drops stored pointer replacing it with the given one.
* @note Copy semantics: reference counter *is* increased.
*/
void grab(ReferenceCounted *object)
{
if (object)
object->grab();
reset(object);
}
public:
irr_ptr() {}
irr_ptr(std::nullptr_t) noexcept {}
irr_ptr(const irr_ptr &b) noexcept { grab(b.get()); }
irr_ptr(irr_ptr &&b) noexcept { reset(b.release()); }
template <typename B, class = typename std::enable_if<std::is_convertible<B *,
ReferenceCounted *>::value>::type>
irr_ptr(const irr_ptr<B> &b) noexcept
{
grab(b.get());
}
template <typename B, class = typename std::enable_if<std::is_convertible<B *,
ReferenceCounted *>::value>::type>
irr_ptr(irr_ptr<B> &&b) noexcept
{
reset(b.release());
}
/** Constructs a shared pointer out of a plain one
* @note Move semantics: reference counter is *not* increased.
*/
explicit irr_ptr(ReferenceCounted *object) noexcept { reset(object); }
~irr_ptr() { reset(); }
irr_ptr &operator=(const irr_ptr &b) noexcept
{
grab(b.get());
return *this;
}
irr_ptr &operator=(irr_ptr &&b) noexcept
{
reset(b.release());
return *this;
}
template <typename B, class = typename std::enable_if<std::is_convertible<B *,
ReferenceCounted *>::value>::type>
irr_ptr &operator=(const irr_ptr<B> &b) noexcept
{
grab(b.get());
return *this;
}
template <typename B, class = typename std::enable_if<std::is_convertible<B *,
ReferenceCounted *>::value>::type>
irr_ptr &operator=(irr_ptr<B> &&b) noexcept
{
reset(b.release());
return *this;
}
ReferenceCounted &operator*() const noexcept { return *value; }
ReferenceCounted *operator->() const noexcept { return value; }
explicit operator ReferenceCounted *() const noexcept { return value; }
explicit operator bool() const noexcept { return !!value; }
/** Returns the stored pointer.
*/
ReferenceCounted *get() const noexcept { return value; }
/** Returns the stored pointer, erasing it from this class.
* @note Move semantics: reference counter is not changed.
*/
ReferenceCounted *release() noexcept
{
ReferenceCounted *object = value;
value = nullptr;
return object;
}
/** Drops stored pointer replacing it with the given one.
* @note Move semantics: reference counter is *not* increased.
*/
void reset(ReferenceCounted *object = nullptr) noexcept
{
if (value)
value->drop();
value = object;
}
};
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