From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 12 Jun 2019 10:13:22 +0000 (+0300)
Subject: Add a utility for registering types for loading
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=676ba621244ea35b69903a7e8aa45637b4bf8648;p=libs%2Fdatafile.git

Add a utility for registering types for loading

Somewhat ironically Collection can't use this because it has much more
complex requirements.
---

diff --git a/source/loadabletyperegistry.h b/source/loadabletyperegistry.h
new file mode 100644
index 0000000..ace98cb
--- /dev/null
+++ b/source/loadabletyperegistry.h
@@ -0,0 +1,83 @@
+#ifndef MSP_DATAFILE_LOADABLETYPEREGISTRY_H_
+#define MSP_DATAFILE_LOADABLETYPEREGISTRY_H_
+
+#include <map>
+#include <string>
+#include <vector>
+#include <msp/core/maputils.h>
+#include <msp/core/noncopyable.h>
+
+namespace Msp {
+namespace DataFile {
+
+/**
+Associates types with keywords for adding to a Loader.  The target Loader class
+must be given as a template parameter, as well as a helper template struct to
+handle the actual adding of keywords.
+*/
+template<typename L, template<typename> class A>
+class LoadableTypeRegistry: public NonCopyable
+{
+private:
+	class TypeBase
+	{
+	protected:
+		std::string keyword;
+
+		TypeBase(const std::string &kw): keyword(kw) { }
+	public:
+		virtual ~TypeBase() { }
+
+		virtual void add(L &) const = 0;
+	};
+
+	template<typename T>
+	class RegisteredType: public TypeBase
+	{
+	public:
+		RegisteredType(const std::string &kw): TypeBase(kw) { }
+
+		virtual void add(L &ldr) const { A<T>::add(ldr, this->keyword); }
+	};
+
+	typedef std::map<std::string, TypeBase *> TypeMap;
+
+	TypeMap types;
+
+public:
+	~LoadableTypeRegistry();
+
+	template<typename T>
+	void register_type(const std::string &);
+
+	void add_all(L &) const;
+};
+
+template<typename L, template<typename> class A>
+LoadableTypeRegistry<L, A>::~LoadableTypeRegistry()
+{
+	for(typename TypeMap::iterator i=types.begin(); i!=types.end(); ++i)
+		delete i->second;
+}
+
+template<typename L, template<typename> class A>
+template<typename T>
+void LoadableTypeRegistry<L, A>::register_type(const std::string &kw)
+{
+	if(types.count(kw))
+		throw key_error(kw);
+
+	types[kw] = new RegisteredType<T>(kw);
+}
+
+template<typename L, template<typename> class A>
+void LoadableTypeRegistry<L, A>::add_all(L &ldr) const
+{
+	for(typename TypeMap::const_iterator i=types.begin(); i!=types.end(); ++i)
+		i->second->add(ldr);
+}
+
+} // namespace DataFile
+} // namespace Msp
+
+#endif