88 lines
2.7 KiB
C++
88 lines
2.7 KiB
C++
/**
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* @file llptrto.h
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* @author Nat Goodspeed
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* @date 2008-08-19
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* @brief LLPtrTo<TARGET> is a template helper to pick either TARGET* or -- when
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* TARGET is a subclass of LLRefCount or LLThreadSafeRefCount --
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* LLPointer<TARGET>. LLPtrTo<> chooses whichever pointer type is best.
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*
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* $LicenseInfo:firstyear=2008&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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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 Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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#if ! defined(LL_LLPTRTO_H)
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#define LL_LLPTRTO_H
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#include "llpointer.h"
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#include "llrefcount.h" // LLRefCount
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#include "llthread.h" // LLThreadSafeRefCount
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#include <boost/type_traits/is_base_of.hpp>
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#include <boost/type_traits/remove_pointer.hpp>
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#include <boost/utility/enable_if.hpp>
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/**
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* LLPtrTo<TARGET>::type is either of two things:
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*
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* * When TARGET is a subclass of either LLRefCount or LLThreadSafeRefCount,
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* LLPtrTo<TARGET>::type is LLPointer<TARGET>.
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* * Otherwise, LLPtrTo<TARGET>::type is TARGET*.
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*
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* This way, a class template can use LLPtrTo<TARGET>::type to select an
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* appropriate pointer type to store.
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*/
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template <class T, class ENABLE=void>
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struct LLPtrTo
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{
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typedef T* type;
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};
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/// specialize for subclasses of LLRefCount
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template <class T>
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struct LLPtrTo<T, typename boost::enable_if< boost::is_base_of<LLRefCount, T> >::type>
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{
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typedef LLPointer<T> type;
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};
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/// specialize for subclasses of LLThreadSafeRefCount
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template <class T>
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struct LLPtrTo<T, typename boost::enable_if< boost::is_base_of<LLThreadSafeRefCount, T> >::type>
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{
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typedef LLPointer<T> type;
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};
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/**
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* LLRemovePointer<PTRTYPE>::type gets you the underlying (pointee) type.
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*/
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template <typename PTRTYPE>
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struct LLRemovePointer
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{
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typedef typename boost::remove_pointer<PTRTYPE>::type type;
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};
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/// specialize for LLPointer<SOMECLASS>
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template <typename SOMECLASS>
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struct LLRemovePointer< LLPointer<SOMECLASS> >
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{
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typedef SOMECLASS type;
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};
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#endif /* ! defined(LL_LLPTRTO_H) */
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