cleaning up thanos-plugin capability

include/inc-core/transform_step.h

@@ -17,18 +17,36 @@
 
 namespace IRDB_SDK
 {
+	class TransformStepState_t; 
+	class ThanosPlugin_t;
+
 	using namespace std;
 	class TransformStep_t
 	{
-		protected:
-			TransformStep_t() { }
 		public:
 			virtual        ~TransformStep_t(void) { } 
 
-			virtual string getStepName(void) const = 0;
+			// abstract methods for plugin to implement
+			virtual string    getStepName(void) const = 0;
+
+			virtual int       parseArgs(const vector<string> step_args) = 0;
+			virtual int       executeStep()                             = 0;
+
+		protected:
+			TransformStep_t() { } // Thanos plugins can create these
+
+			// helper methods for plugin to use 
+			virtual File_t*              getMainFile()    final; 
+			virtual FileIR_t*            getMainFileIR()  final; 
+			virtual DatabaseID_t         getVariantID()   final; 
+			virtual IRDBObjects_t*const  getIRDBObjects() final; 
+
+		private:
+			// private data can only be accessed by protected accessors.
+			TransformStepState_t* m_state = nullptr;
+			virtual void setState(TransformStepState_t* p_state) final;
+			friend class ThanosPlugin_t;
 
-			virtual int    parseArgs(const vector<string> step_args)      = 0;
-			virtual int    executeStep(IRDBObjects_t *const irdb_objects) = 0;
 	};
 
 }
@@ -38,6 +56,10 @@ namespace IRDB_SDK
 // so that thanos can use it as a factory to create your transform class.  It must
 // follow this signature:
 //
-// extern "C" std::shared_ptr<TransformStep_t> GetTransformStep(void);    
+// extern "C" std::shared_ptr<TransformStep_t> getTransformStep(void);    
+// {
+//         return shared_ptr<TransformStep_t>(new YourClassHere_t());
+// }
+