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Diffstat (limited to 'include/salhelper/simplereferenceobject.hxx')
-rw-r--r-- | include/salhelper/simplereferenceobject.hxx | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/include/salhelper/simplereferenceobject.hxx b/include/salhelper/simplereferenceobject.hxx new file mode 100644 index 0000000000..ac721ad3da --- /dev/null +++ b/include/salhelper/simplereferenceobject.hxx @@ -0,0 +1,122 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed + * with this work for additional information regarding copyright + * ownership. The ASF licenses this file to you under the Apache + * License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of + * the License at http://www.apache.org/licenses/LICENSE-2.0 . + */ + +/* + * This file is part of LibreOffice published API. + */ + +#ifndef INCLUDED_SALHELPER_SIMPLEREFERENCEOBJECT_HXX +#define INCLUDED_SALHELPER_SIMPLEREFERENCEOBJECT_HXX + +#include "osl/interlck.h" +#include "salhelper/salhelperdllapi.h" + +#include <cstddef> +#include <new> + +namespace salhelper { + +/** A simple base implementation for reference-counted objects. + + Classes that want to implement a reference-counting mechanism based on the + acquire()/release() interface should derive from this class. + + The reason to have class local operators new and delete here is technical. + Imagine a class D derived from SimpleReferenceObject, but implemented in + another shared library that happens to use different global operators new + and delete from those used in this shared library (which, sadly, seems to + be possible with shared libraries). Now, without the class local + operators new and delete here, a code sequence like "new D" would use the + global operator new as found in the other shared library, while the code + sequence "delete this" in release() would use the global operator delete + as found in this shared library---and these two operators would not be + guaranteed to match. + + There are no overloaded operators new and delete for placement new here, + because it is felt that the concept of placement new does not work well + with the concept of reference-counted objects; so it seems best to simply + leave those operators out. + + The same problem as with operators new and delete would also be there with + operators new[] and delete[]. But since arrays of reference-counted + objects are of no use, anyway, it seems best to simply + define operators new[] and delete[] as deleted. + */ +class SALHELPER_DLLPUBLIC SimpleReferenceObject +{ +public: + SimpleReferenceObject(): m_nCount(0) {} + + /** @attention + The results are undefined if, for any individual instance of + SimpleReferenceObject, the total number of calls to acquire() exceeds + the total number of calls to release() by a platform dependent amount + (which, hopefully, is quite large). + */ + void acquire() + { osl_atomic_increment(&m_nCount); } + + void release() + { if (osl_atomic_decrement(&m_nCount) == 0) delete this; } + + /** see general class documentation + */ + static void * operator new(std::size_t nSize); + + /** see general class documentation + */ + static void * operator new(std::size_t nSize, + std::nothrow_t const & rNothrow); + + /** see general class documentation + */ + static void operator delete(void * pPtr); + + /** see general class documentation + */ + static void operator delete(void * pPtr, std::nothrow_t const & rNothrow); + +protected: + virtual ~SimpleReferenceObject() COVERITY_NOEXCEPT_FALSE; + + oslInterlockedCount m_nCount; + +private: + /** not implemented + */ + SimpleReferenceObject(SimpleReferenceObject &) SAL_DELETED_FUNCTION; + + /** not implemented + */ + void operator =(SimpleReferenceObject) SAL_DELETED_FUNCTION; + + /** see general class documentation + */ + static void * operator new[](std::size_t) SAL_DELETED_FUNCTION; + + /** see general class documentation + */ + static void operator delete[](void * pPtr) SAL_DELETED_FUNCTION; +}; + +} + +#endif // INCLUDED_SALHELPER_SIMPLEREFERENCEOBJECT_HXX + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |