/** * @file llptrto.h * @author Nat Goodspeed * @date 2008-08-19 * @brief LLPtrTo<TARGET> is a template helper to pick either TARGET* or -- when * TARGET is a subclass of LLRefCount or LLThreadSafeRefCount -- * LLPointer<TARGET>. LLPtrTo<> chooses whichever pointer type is best. * * $LicenseInfo:firstyear=2008&license=viewerlgpl$ * Second Life Viewer Source Code * Copyright (C) 2010, Linden Research, Inc. * * This library 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; * version 2.1 of the License only. * * This library 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 library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA * $/LicenseInfo$ */ #if ! defined(LL_LLPTRTO_H) #define LL_LLPTRTO_H #include "llpointer.h" #include "llrefcount.h" // LLRefCount #include "llthread.h" // LLThreadSafeRefCount #include <boost/type_traits/is_base_of.hpp> #include <boost/type_traits/remove_pointer.hpp> #include <boost/utility/enable_if.hpp> /** * LLPtrTo<TARGET>::type is either of two things: * * * When TARGET is a subclass of either LLRefCount or LLThreadSafeRefCount, * LLPtrTo<TARGET>::type is LLPointer<TARGET>. * * Otherwise, LLPtrTo<TARGET>::type is TARGET*. * * This way, a class template can use LLPtrTo<TARGET>::type to select an * appropriate pointer type to store. */ template <class T, class ENABLE=void> struct LLPtrTo { typedef T* type; }; /// specialize for subclasses of LLRefCount template <class T> struct LLPtrTo<T, typename boost::enable_if< boost::is_base_of<LLRefCount, T> >::type> { typedef LLPointer<T> type; }; /// specialize for subclasses of LLThreadSafeRefCount template <class T> struct LLPtrTo<T, typename boost::enable_if< boost::is_base_of<LLThreadSafeRefCount, T> >::type> { typedef LLPointer<T> type; }; /** * LLRemovePointer<PTRTYPE>::type gets you the underlying (pointee) type. */ template <typename PTRTYPE> struct LLRemovePointer { typedef typename boost::remove_pointer<PTRTYPE>::type type; }; /// specialize for LLPointer<SOMECLASS> template <typename SOMECLASS> struct LLRemovePointer< LLPointer<SOMECLASS> > { typedef SOMECLASS type; }; #endif /* ! defined(LL_LLPTRTO_H) */