Add singleton class

inferno/src/inferno/singleton.h

@@ -0,0 +1,31 @@
+#ifndef SINGLETON_H
+#define SINGLETON_H
+
+#include <memory> // std::unique_ptr
+
+namespace Inferno {
+
+	template<typename T>
+	class Singleton {
+	public:
+		static inline T& the() {
+			static const std::unique_ptr<T> instance { new T { s {} } };
+			return *instance;
+		}
+
+		// Remove copy constructor and copy assignment operator
+		Singleton(const Singleton&) = delete;
+		Singleton& operator=(const Singleton&) = delete;
+		Singleton(Singleton&&) = delete;
+		Singleton& operator=(Singleton&&) = delete;
+
+	protected:
+		Singleton() {}
+
+		// Constructor token
+		struct s {};
+	};
+
+} // namespace Inferno
+
+#endif // SINGLETON_H