169 lines
4.0 KiB
C++
169 lines
4.0 KiB
C++
///@file
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/// Wrapper class for keeping Nasal objects save from the garbage collector.
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//
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// Copyright (C) 2013 Thomas Geymayer <tomgey@gmail.com>
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library 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 GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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#ifndef SG_NASAL_OBJECT_HOLDER_HXX_
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#define SG_NASAL_OBJECT_HOLDER_HXX_
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#include <simgear/nasal/nasal.h>
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#include <simgear/structure/SGSharedPtr.hxx>
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namespace nasal
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{
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/**
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* Usable for example as empty base class if a base class is required.(Eg. as
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* parameter for a mixin class).
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*/
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struct empty_class {};
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/**
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* Prevent a Nasal object from being destroyed by the garbage collector during
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* the lifetime of this object.
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*/
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template<class Base = empty_class>
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class ObjectHolder:
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public Base
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{
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public:
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using Ref = SGSharedPtr<ObjectHolder<Base>>;
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/**
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* @param obj Object to save
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*/
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explicit ObjectHolder(naRef obj);
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/**
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*
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*/
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ObjectHolder();
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/**
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*
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*/
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~ObjectHolder();
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/**
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* Get captured Nasal object
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*/
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naRef get_naRef() const;
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/**
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* Release the managed object
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*/
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void reset();
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/**
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* Replaces the managed object (the old object is released)
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*
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* @param obj New object to save
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*/
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void reset(naRef obj);
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/**
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* Check if there is a managed object
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*/
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bool valid() const;
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/**
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* Save the given object as long as the returned holder exists.
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*
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* @param obj Object to save
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*/
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static Ref makeShared(naRef obj);
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protected:
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naRef _ref;
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int _gc_key;
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};
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//----------------------------------------------------------------------------
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template<class Base>
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ObjectHolder<Base>::~ObjectHolder()
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{
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if( !naIsNil(_ref) )
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naGCRelease(_gc_key);
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}
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//----------------------------------------------------------------------------
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template<class Base>
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naRef ObjectHolder<Base>::get_naRef() const
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{
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return _ref;
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}
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//----------------------------------------------------------------------------
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template<class Base>
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void ObjectHolder<Base>::reset()
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{
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if( !naIsNil(_ref) )
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naGCRelease(_gc_key);
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_ref = naNil();
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_gc_key = 0;
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}
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//----------------------------------------------------------------------------
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template<class Base>
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void ObjectHolder<Base>::reset(naRef obj)
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{
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if( !naIsNil(_ref) )
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naGCRelease(_gc_key);
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_ref = obj;
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_gc_key = naGCSave(obj);
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}
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//----------------------------------------------------------------------------
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template<class Base>
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bool ObjectHolder<Base>::valid() const
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{
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return !naIsNil(_ref);
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}
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//----------------------------------------------------------------------------
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template<class Base>
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ObjectHolder<Base>::ObjectHolder(naRef obj):
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_ref(obj),
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_gc_key(naIsNil(obj) ? 0 : naGCSave(obj))
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{
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}
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//----------------------------------------------------------------------------
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template<class Base>
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ObjectHolder<Base>::ObjectHolder():
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_ref(naNil()),
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_gc_key(0)
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{
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}
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//----------------------------------------------------------------------------
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template<class Base>
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typename ObjectHolder<Base>::Ref
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ObjectHolder<Base>::makeShared(naRef obj)
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{
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return Ref( new ObjectHolder<Base>(obj) );
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}
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} // namespace nasal
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#endif /* SG_NASAL_OBJECT_HOLDER_HXX_ */
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