/** * @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) { 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