Added Singleton template class.

singleton.h

@@ -0,0 +1,114 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+
+Copyright(c) 2014 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_SINGLETON__
+#define __ETL_SINGLETON__
+
+///\defgroup singleton singleton
+/// Templated version of the sing;eton pattern.
+///\ingroup etl
+
+namespace etl
+{
+	//*************************************************************************
+    /// Singleton pattern base class.
+    /// \ingroup singleton
+    //*************************************************************************
+    template<typename T>
+    class singleton
+    {  
+    public:
+
+        //*********************************************************************
+        /// Constructor.
+        //*********************************************************************
+        singleton()
+        {
+        }
+
+        //*********************************************************************
+        /// Destructor.
+        //*********************************************************************
+        virtual ~singleton()
+        {
+        }
+
+        //*********************************************************************
+        /// Returns a reference to the instance.
+        ///\return A reference to the instance.
+        //*********************************************************************
+        T& operator *()
+        {
+            return instance();
+        }
+
+        //*********************************************************************
+        /// Returns a const reference to the instance.
+        /// \return A const reference to the instance.
+        //*********************************************************************
+        // @short-legal-notice
+        //*********************************************************************
+        const T& operator *() const
+        {
+            return instance();
+        }
+
+        //*********************************************************************
+        /// Returns a pointer to the instance.
+        /// \return A pointer to the instance.
+        //*********************************************************************
+        T* operator ->()
+        {
+            return &instance();
+        }
+
+    //*********************************************************************
+    /// Returns a const pointer to the instance.
+    /// \return A const pointer to the instance.
+    //*********************************************************************
+    const T* operator ->() const
+    {
+      return &instance();
+    }
+
+    private:
+
+    //*************************************************************************
+    /// Returns a reference to the instance.
+    ///\return A reference to the instance.
+    //*************************************************************************
+    static T &instance()
+    {
+      static T the_instance;
+
+      return the_instance;
+    }
+  };
+}
+
+#endif