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DependentExtensions/cat/Singleton.hpp

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+/*
+	Copyright (c) 2009-2010 Christopher A. Taylor.  All rights reserved.
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions are met:
+
+	* Redistributions of source code must retain the above copyright notice,
+	  this list of conditions and the following disclaimer.
+	* Redistributions in binary form must reproduce the above copyright notice,
+	  this list of conditions and the following disclaimer in the documentation
+	  and/or other materials provided with the distribution.
+	* Neither the name of LibCat nor the names of its contributors may be used
+	  to endorse or promote products derived from this software without
+	  specific prior written permission.
+
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+	AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+	ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+	LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+	CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+	SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+	INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+	CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+	ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+	POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef CAT_SINGLETON_HPP
+#define CAT_SINGLETON_HPP
+
+#include <cat/Platform.hpp>
+
+namespace cat {
+
+
+// Derived class should define the constructor using this macro:
+#define CAT_SINGLETON(subclass) \
+    private: \
+        friend class Singleton<subclass>; \
+        subclass()
+
+
+//// Singleton
+
+template<class T> class Singleton
+{
+protected:
+    Singleton<T>() {}
+    Singleton<T>(Singleton<T> &) {}
+    Singleton<T> &operator=(Singleton<T> &) {}
+
+public:
+    static T *ii;
+
+public:
+    CAT_INLINE static T *ref()
+    {
+        if (ii) return ii;
+        return ii = new T;
+    }
+	CAT_INLINE static void deallocate()
+	{
+		if (ii)
+		{
+			delete ii;
+			ii = 0;
+		}
+	}
+
+	virtual ~Singleton() {}
+};
+
+// TODO: I'm actually not 100% sure this always works
+template<class T> T *Singleton<T>::ii = 0;
+
+
+} // namespace cat
+
+#endif // CAT_SINGLETON_HPP