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/**
* @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.
*
* $LicenseInfo:firstyear=2008&license=viewergpl$
*
* Copyright (c) 2008-2009, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at
* http://secondlifegrid.net/programs/open_source/licensing/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
* $/LicenseInfo$
*/
#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) */
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