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Diffstat (limited to 'indra/llcommon/llsafehandle.h')
| -rw-r--r-- | indra/llcommon/llsafehandle.h | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/indra/llcommon/llsafehandle.h b/indra/llcommon/llsafehandle.h new file mode 100644 index 0000000000..1f7c682fd1 --- /dev/null +++ b/indra/llcommon/llsafehandle.h @@ -0,0 +1,167 @@ +/** + * @file llsafehandle.h + * @brief Reference-counted object where Object() is valid, not NULL. + * + * $LicenseInfo:firstyear=2002&license=viewergpl$ + * + * 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 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; } + // 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 |