843383fdc3
flightgear::addons::shared_ptr_traits allows one to easily switch for instance from an SGSharedPtr<T> to an std::shared_ptr<T> for "all" uses of a particular T, and automatically have std::make_shared<T>(...) used instead of SGSharedPtr<T>(new T(...)) when creating a shared instance of T. This is interesting because std::make_shared<T>() allocates all needed memory as one block, whereas std::shared_ptr<T>(new T(args...)) would perform at least two allocations (one for the object T and one for the control block of the shared pointer). This is done via static methods (one for each kind of smart pointer): shared_ptr_traits<SGSharedPtr<T>>::makeStrongRef() shared_ptr_traits<std::shared_ptr<T>>::makeStrongRef() that forward their arguments in the same way as std::make_shared<T>().
67 lines
1.7 KiB
C++
67 lines
1.7 KiB
C++
// -*- coding: utf-8 -*-
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//
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// pointer_traits.hxx --- Pointer traits classes
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// Copyright (C) 2018 Florent Rougon
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with this program; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef FG_ADDON_POINTER_TRAITS_HXX
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#define FG_ADDON_POINTER_TRAITS_HXX
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#include <memory>
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#include <utility>
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#include <simgear/structure/SGSharedPtr.hxx>
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namespace flightgear
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{
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namespace addons
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{
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template <typename T>
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struct shared_ptr_traits;
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template <typename T>
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struct shared_ptr_traits<SGSharedPtr<T>>
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{
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using element_type = T;
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using strong_ref = SGSharedPtr<T>;
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template <typename ...Args>
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static strong_ref makeStrongRef(Args&& ...args)
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{
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return strong_ref(new T(std::forward<Args>(args)...));
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}
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};
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template <typename T>
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struct shared_ptr_traits<std::shared_ptr<T>>
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{
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using element_type = T;
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using strong_ref = std::shared_ptr<T>;
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template <typename ...Args>
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static strong_ref makeStrongRef(Args&& ...args)
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{
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return std::make_shared<T>(std::forward<Args>(args)...);
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}
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};
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} // of namespace addons
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} // of namespace flightgear
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#endif // of FG_ADDON_POINTER_TRAITS_HXX
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