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/**
* @file llpointer.h
* @brief A reference-counted pointer for objects derived from LLRefCount
*
* $LicenseInfo:firstyear=2002&license=viewergpl$
*
* Copyright (c) 2002-2009, 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.
* $/LicenseInfo$
*/
#ifndef LLPOINTER_H
#define LLPOINTER_H
#include "llerror.h" // *TODO: consider eliminating this
//----------------------------------------------------------------------------
// RefCount objects should generally only be accessed by way of LLPointer<>'s
// NOTE: LLPointer<LLFoo> x = new LLFoo(); MAY NOT BE THREAD SAFE
// if LLFoo::LLFoo() does anything like put itself in an update queue.
// The queue may get accessed before it gets assigned to x.
// The correct implementation is:
// LLPointer<LLFoo> x = new LLFoo; // constructor does not do anything interesting
// x->instantiate(); // does stuff like place x into an update queue
// see llthread.h for LLThreadSafeRefCount
//----------------------------------------------------------------------------
// Note: relies on Type having ref() and unref() methods
template <class Type> class LLPointer
{
public:
LLPointer() :
mPointer(NULL)
{
}
LLPointer(Type* ptr) :
mPointer(ptr)
{
ref();
}
LLPointer(const LLPointer<Type>& ptr) :
mPointer(ptr.mPointer)
{
ref();
}
// support conversion up the type hierarchy. See Item 45 in Effective C++, 3rd Ed.
template<typename Subclass>
LLPointer(const LLPointer<Subclass>& ptr) :
mPointer(ptr.get())
{
ref();
}
~LLPointer()
{
unref();
}
Type* get() const { return mPointer; }
const Type* operator->() const { return mPointer; }
Type* operator->() { return mPointer; }
const Type& operator*() const { return *mPointer; }
Type& operator*() { return *mPointer; }
operator BOOL() const { return (mPointer != NULL); }
operator bool() const { return (mPointer != NULL); }
bool operator!() const { return (mPointer == NULL); }
bool isNull() const { return (mPointer == NULL); }
bool notNull() const { return (mPointer != NULL); }
operator Type*() const { return mPointer; }
operator const Type*() const { return mPointer; }
bool operator !=(Type* ptr) const { return (mPointer != ptr); }
bool operator ==(Type* ptr) const { return (mPointer == ptr); }
bool operator ==(const LLPointer<Type>& ptr) const { return (mPointer == ptr.mPointer); }
bool operator < (const LLPointer<Type>& ptr) const { return (mPointer < ptr.mPointer); }
bool operator > (const LLPointer<Type>& ptr) const { return (mPointer > ptr.mPointer); }
LLPointer<Type>& operator =(Type* ptr)
{
if( mPointer != ptr )
{
unref();
mPointer = ptr;
ref();
}
return *this;
}
LLPointer<Type>& operator =(const LLPointer<Type>& ptr)
{
if( mPointer != ptr.mPointer )
{
unref();
mPointer = ptr.mPointer;
ref();
}
return *this;
}
// support assignment up the type hierarchy. See Item 45 in Effective C++, 3rd Ed.
template<typename Subclass>
LLPointer<Type>& operator =(const LLPointer<Subclass>& ptr)
{
if( mPointer != ptr.get() )
{
unref();
mPointer = ptr.get();
ref();
}
return *this;
}
// Just exchange the pointers, which will not change the reference counts.
static void swap(LLPointer<Type>& a, LLPointer<Type>& b)
{
Type* temp = a.mPointer;
a.mPointer = b.mPointer;
b.mPointer = temp;
}
protected:
void ref()
{
if (mPointer)
{
mPointer->ref();
}
}
void unref()
{
if (mPointer)
{
Type *tempp = mPointer;
mPointer = NULL;
tempp->unref();
if (mPointer != NULL)
{
llwarns << "Unreference did assignment to non-NULL because of destructor" << llendl;
unref();
}
}
}
protected:
Type* mPointer;
};
#endif
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