Util: Add singleton class

src/util/singleton.h

@@ -0,0 +1,50 @@
+#ifndef SINGLETON_H
+#define SINGLETON_H
+
+#include <cassert>
+
+namespace Util {
+
+template<typename T>
+class Singleton {
+public:
+	static inline T& the()
+	{
+		if (s_instance == nullptr) {
+			s_instance = new T { s {} };
+		}
+
+		return *s_instance;
+	}
+
+	static inline void destroy()
+	{
+		if (s_instance) {
+			delete s_instance;
+		}
+
+		s_instance = nullptr;
+	}
+
+	// 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 {};
+
+private:
+	static T* s_instance;
+};
+
+template<typename T>
+T* Singleton<T>::s_instance = nullptr;
+
+} // namespace Util
+
+#endif // SINGLETON_H