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authortpearson <tpearson@283d02a7-25f6-0310-bc7c-ecb5cbfe19da>2010-01-05 00:01:18 +0000
committertpearson <tpearson@283d02a7-25f6-0310-bc7c-ecb5cbfe19da>2010-01-05 00:01:18 +0000
commit42995d7bf396933ee60c5f89c354ea89cf13df0d (patch)
treecfdcea0ac57420e7baf570bfe435e107bb842541 /mcop/weakreference.h
downloadarts-42995d7bf396933ee60c5f89c354ea89cf13df0d.tar.gz
arts-42995d7bf396933ee60c5f89c354ea89cf13df0d.zip
Copy of aRts for Trinity modifications
git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/dependencies/arts@1070145 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
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+ /*
+
+ Copyright (C) 2000-2002 Stefan Westerfeld
+ stefan@space.twc.de
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public License
+ along with this library; see the file COPYING.LIB. If not, write to
+ the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+
+ */
+
+/*
+ * BC - Status (2002-03-08): WeakReference(Base)
+ *
+ * Has to be kept binary compatible by not touching it. Add a new class if
+ * you need something else.
+ */
+
+#ifndef MCOP_WEAKREFERENCE_H
+#define MCOP_WEAKREFERENCE_H
+
+#include "arts_export.h"
+
+namespace Arts {
+
+class ARTS_EXPORT WeakReferenceBase {
+public:
+ virtual void release() = 0;
+};
+
+/**
+ * The WeakReference class can be used to safely store an object, without
+ * disallowing that it gets destroyed. A typical situation where you may want
+ * to use this is when you implement a datastructure, where A refers B, and
+ * B refers A. Using "normal" references, this structure would never get
+ * freed.
+ *
+ * Usage example:
+ *
+ * Synth_WAVE_SIN sin;
+ * WeakReference<Synth_PLAY_WAV> weak_sin;
+ *
+ * {
+ * Synth_WAVE_SIN test = weak_sin;
+ * if(test.isNull())
+ * printf("#1 missing object\n");
+ * else
+ * test.start();
+ * }
+ *
+ * // now, the strong reference leaves
+ * sin = Synth_WAVE_SIN::null();
+ *
+ * {
+ * Synth_WAVE_SIN test = weak_sin;
+ * if(test.isNull())
+ * printf("#2 missing object\n");
+ * else
+ * test.stop();
+ *
+ * This would output "#2 missing object".
+ *
+ */
+
+template<class SmartWrapper>
+class WeakReference : public WeakReferenceBase
+{
+private:
+ typename SmartWrapper::_base_class *content;
+
+public:
+ WeakReference()
+ {
+ content = 0;
+ }
+ WeakReference(const WeakReference<SmartWrapper>& source)
+ :WeakReferenceBase(source), content(source.content)
+ {
+ if(content)
+ content->_addWeakReference(this);
+ }
+ WeakReference(SmartWrapper& source)
+ {
+ content = source._base();
+ if(content)
+ content->_addWeakReference(this);
+ }
+ inline WeakReference<SmartWrapper>& operator=(const
+ WeakReference<SmartWrapper>& source)
+ {
+ release();
+ content = source.content;
+ if(content)
+ content->_addWeakReference(this);
+ return *this;
+ }
+ virtual ~WeakReference()
+ {
+ release();
+ }
+ void release()
+ {
+ if(content)
+ {
+ content->_removeWeakReference(this);
+ content = 0;
+ }
+ }
+ inline operator SmartWrapper() const
+ {
+ if(content)
+ return SmartWrapper::_from_base(content->_copy());
+ else
+ return SmartWrapper::null();
+ }
+};
+
+}
+
+#endif /* MCOP_WEAKREFERENCE_H */