llsafehandle.h
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- /**
- * @file llsafehandle.h
- * @brief Reference-counted object where Object() is valid, not NULL.
- *
- * $LicenseInfo:firstyear=2002&license=viewergpl$
- *
- * Copyright (c) 2002-2010, 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 LLSAFEHANDLE_H
- #define LLSAFEHANDLE_H
- #include "llerror.h" // *TODO: consider eliminating this
- // Expands LLPointer to return a pointer to a special instance of class Type instead of NULL.
- // This is useful in instances where operations on NULL pointers are semantically safe and/or
- // when error checking occurs at a different granularity or in a different part of the code
- // than when referencing an object via a LLSafeHandle.
- template <class Type>
- class LLSafeHandle
- {
- public:
- LLSafeHandle() :
- mPointer(NULL)
- {
- }
- LLSafeHandle(Type* ptr) :
- mPointer(NULL)
- {
- assign(ptr);
- }
- LLSafeHandle(const LLSafeHandle<Type>& ptr) :
- mPointer(NULL)
- {
- assign(ptr.mPointer);
- }
- // support conversion up the type hierarchy. See Item 45 in Effective C++, 3rd Ed.
- template<typename Subclass>
- LLSafeHandle(const LLSafeHandle<Subclass>& ptr) :
- mPointer(NULL)
- {
- assign(ptr.get());
- }
- ~LLSafeHandle()
- {
- unref();
- }
- const Type* operator->() const { return nonNull(mPointer); }
- Type* operator->() { return nonNull(mPointer); }
- Type* get() const { return mPointer; }
- void clear() { assign(NULL); }
- // we disallow these operations as they expose our null objects to direct manipulation
- // and bypass the reference counting semantics
- //const Type& operator*() const { return *nonNull(mPointer); }
- //Type& operator*() { return *nonNull(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 LLSafeHandle<Type>& ptr) const { return (mPointer == ptr.mPointer); }
- bool operator < (const LLSafeHandle<Type>& ptr) const { return (mPointer < ptr.mPointer); }
- bool operator > (const LLSafeHandle<Type>& ptr) const { return (mPointer > ptr.mPointer); }
- LLSafeHandle<Type>& operator =(Type* ptr)
- {
- assign(ptr);
- return *this;
- }
- LLSafeHandle<Type>& operator =(const LLSafeHandle<Type>& ptr)
- {
- assign(ptr.mPointer);
- return *this;
- }
- // support assignment up the type hierarchy. See Item 45 in Effective C++, 3rd Ed.
- template<typename Subclass>
- LLSafeHandle<Type>& operator =(const LLSafeHandle<Subclass>& ptr)
- {
- assign(ptr.get());
- return *this;
- }
- public:
- typedef Type* (*NullFunc)();
- static const NullFunc sNullFunc;
- 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();
- }
- }
- }
- void assign(Type* ptr)
- {
- if( mPointer != ptr )
- {
- unref();
- mPointer = ptr;
- ref();
- }
- }
- static Type* nonNull(Type* ptr)
- {
- return ptr == NULL ? sNullFunc() : ptr;
- }
- protected:
- Type* mPointer;
- };
- #endif