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Diffstat (limited to 'indra/llcommon/llpointer.h')
| -rw-r--r-- | indra/llcommon/llpointer.h | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/indra/llcommon/llpointer.h b/indra/llcommon/llpointer.h new file mode 100644 index 0000000000..affa040602 --- /dev/null +++ b/indra/llcommon/llpointer.h @@ -0,0 +1,170 @@ +/** + * @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 |