Create factory.h

nopcoder · nopcoder · commit 330e2aebc579 · 2013-09-07T17:22:53.000+03:00
diff --git a/factory.h b/factory.h
@@ -0,0 +1,51 @@
+#ifndef __FACTORY_H__
+#define __FACTORY_H__
+
+#include <string>
+#include <map>
+#include <cassert>
+
+template<typename TBase, typename TKey = std::string>
+class Factory
+{
+public:
+	static Factory* instance() {
+		static Factory singleton;
+		return &singleton;
+	}
+
+	struct BuilderBase
+	{
+		virtual TBase* create() = 0;
+	};
+
+	template<typename TDerived>
+	struct Builder : public BuilderBase
+	{
+		Builder(const TKey& id) {
+			Factory<TBase, TKey>::instance()->register_builder(id, this);
+		}
+		TBase* create() { return new TDerived; }
+	};
+
+	TBase* create(const TKey& id) const {
+		std::map<TKey, BuilderBase*>::const_iterator it = m_builders.find(id);
+		return (it == m_builders.end()) ? NULL : it->second->create();
+	}
+
+	void register_builder(const TKey& id, BuilderBase* bb) {
+		std::pair<std::map<TKey, BuilderBase*>::iterator, bool> p = 
+			m_builders.insert(std::make_pair(id, bb));
+		assert(p.second); // builder 'id' already registered
+	}
+
+private:
+	Factory() {}
+	~Factory() {}
+	Factory(const Factory&);
+	Factory& operator=(const Factory&);
+
+	std::map<TKey, BuilderBase*> m_builders;
+};
+
+#endif
