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/**
* @file llpointer.h
* @brief A reference-counted pointer for objects derived from LLRefCount
*
* $LicenseInfo:firstyear=2002&license=viewerlgpl$
* 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
* $/LicenseInfo$
*/
#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; }
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)
{
assign(ptr);
return *this;
}
LLPointer<Type>& operator =(const LLPointer<Type>& ptr)
{
assign(ptr);
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)
{
assign(ptr.get());
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:
#ifdef LL_LIBRARY_INCLUDE
void ref();
void unref();
#else
void assign(const LLPointer<Type>& ptr)
{
if( mPointer != ptr.mPointer )
{
unref();
mPointer = ptr.mPointer;
ref();
}
}
void ref()
{
if (mPointer)
{
mPointer->ref();
}
}
void unref()
{
if (mPointer)
{
Type *temp = mPointer;
mPointer = NULL;
temp->unref();
if (mPointer != NULL)
{
llwarns << "Unreference did assignment to non-NULL because of destructor" << llendl;
unref();
}
}
}
#endif
protected:
Type* mPointer;
};
template<typename Type>
class LLCopyOnWritePointer : public LLPointer<Type>
{
public:
typedef LLCopyOnWritePointer<Type> self_t;
typedef LLPointer<Type> pointer_t;
LLCopyOnWritePointer()
{}
LLCopyOnWritePointer(Type* ptr)
: LLPointer<Type>(ptr)
{}
LLCopyOnWritePointer(LLPointer<Type>& ptr)
: LLPointer<Type>(ptr)
{}
Type* write()
{
makeUnique();
return pointer_t::mPointer;
}
void makeUnique()
{
if (pointer_t::notNull() && pointer_t::mPointer->getNumRefs() > 1)
{
*(pointer_t*)(this) = new Type(*pointer_t::mPointer);
}
}
};
#endif
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