From b2fc6c70434674d74551c3a6c01ffb3233499312 Mon Sep 17 00:00:00 2001
From: Willem Jan Palenstijn <WillemJan.Palenstijn@uantwerpen.be>
Date: Mon, 1 Jul 2013 22:34:11 +0000
Subject: Update version to 1.3

---
 include/astra/Singleton.h | 87 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 include/astra/Singleton.h

(limited to 'include/astra/Singleton.h')

diff --git a/include/astra/Singleton.h b/include/astra/Singleton.h
new file mode 100644
index 0000000..5a494e4
--- /dev/null
+++ b/include/astra/Singleton.h
@@ -0,0 +1,87 @@
+/*
+-----------------------------------------------------------------------
+Copyright 2012 iMinds-Vision Lab, University of Antwerp
+
+Contact: astra@ua.ac.be
+Website: http://astra.ua.ac.be
+
+
+This file is part of the
+All Scale Tomographic Reconstruction Antwerp Toolbox ("ASTRA Toolbox").
+
+The ASTRA Toolbox is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+The ASTRA Toolbox 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with the ASTRA Toolbox. If not, see <http://www.gnu.org/licenses/>.
+
+-----------------------------------------------------------------------
+$Id$
+*/
+
+#ifndef _INC_ASTRA_SINGLETON
+#define _INC_ASTRA_SINGLETON
+
+#include <cassert>
+
+#ifndef _MSC_VER
+#include <stdint.h>
+#endif
+
+namespace astra {
+	/** 
+	 * This singleton interface class ensures that any of its children can be instatiated only once. This is used by the ObjectFactories.
+	 **/
+template<typename T>
+class Singleton {
+
+	public:
+
+		// constructor
+		Singleton() {
+			assert(!m_singleton);
+			int offset = (uintptr_t)(T*)1 - (uintptr_t)(Singleton<T>*)(T*)1;
+			m_singleton = (T*)((uintptr_t)this + offset);
+		};
+
+		// destructor
+		virtual ~Singleton() {
+			assert(m_singleton);
+			m_singleton = 0;
+		}
+
+		// get singleton
+		static T& getSingleton() {
+			if (!m_singleton)
+				m_singleton = new T();
+			return *m_singleton;
+		}
+		static T* getSingletonPtr() {
+			if (!m_singleton)
+				m_singleton = new T();
+			return m_singleton;
+		}
+
+	private:
+
+		// the singleton
+		static T* m_singleton;
+
+};
+
+#define DEFINE_SINGLETON(T) template<> T* Singleton<T >::m_singleton = 0
+
+// This is a hack to support statements like
+// DEFINE_SINGLETON2(CTemplatedClass<C1, C2>);
+#define DEFINE_SINGLETON2(A,B) template<> A,B* Singleton<A,B >::m_singleton = 0
+
+} // end namespace
+
+#endif
-- 
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