params: Implement proper params::output value-to-name mapping.

sources/core/params.cpp

 /* ALTA --- Analysis of Bidirectional Reflectance Distribution Functions
 
    Copyright (C) 2014 CNRS
-   Copyright (C) 2013, 2014 Inria
+   Copyright (C) 2013, 2014, 2015 Inria
 
    This file is part of ALTA.
 
@@ -81,6 +81,31 @@ static const std::map<params::input, const param_info> input_map = create_map();
 //};
 //#endif
 
+static std::map<params::output, std::string> create_output_map()
+{
+		std::map<params::output, std::string> result;
+
+#define STRINGIFY_(x) #x
+#define STRINGIFY(x)  STRINGIFY_(x)
+#define DEFINE_MAPPING(name)										\
+		result[params::name] = STRINGIFY(name);
+
+		DEFINE_MAPPING(INV_STERADIAN);
+		DEFINE_MAPPING(INV_STERADIAN_COSINE_FACTOR);
+		DEFINE_MAPPING(ENERGY);
+		DEFINE_MAPPING(RGB_COLOR);
+		DEFINE_MAPPING(XYZ_COLOR);
+
+#undef DEFINE_MAPPING
+#undef STRINGIFY
+#undef STRINGIFY_
+
+		return result;
+}
+
+static const std::map<params::output, std::string> output_map =
+		create_output_map();
+
 void params::to_cartesian(const double* invec, params::input intype,
 		double* outvec)
 {
@@ -566,6 +591,18 @@ std::string params::get_name(const params::input param)
 	return std::string("UNKNOWN_INPUT");
 }
 
+std::string params::get_name(const params::output param)
+{
+		std::map<params::output, std::string>::const_iterator it = output_map.find(param);
+		if (it != output_map.end())
+		{
+				return it->second;
+		}
+
+		static const std::string unknown = "UNKNOWN_OUTPUT";
+		return unknown;
+}
+
 int  params::dimension(params::input t)
 {
 	std::map<params::input, const param_info>::const_iterator it = input_map.find(t);

sources/core/params.h

 /* ALTA --- Analysis of Bidirectional Reflectance Distribution Functions
 
    Copyright (C) 2014 CNRS
-   Copyright (C) 2013, 2014 Inria
+   Copyright (C) 2013, 2014, 2015 Inria
 
    This file is part of ALTA.
 
@@ -135,10 +135,7 @@ class params
 		  //! type.
 		  //! \todo Finish this implementation. It requires another static
 		  //! object.
-		  static std::string get_name(const params::output)
-		  {
-			  return std::string("UNKNOWN_OUTPUT");
-		  }
+		  static std::string get_name(const params::output);
 
         //! \brief static function for input type convertion. This
         //! function allocate the resulting vector.