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+/* -*- 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 .
+ */
+
+#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: */