Implemented Phase output again

Added PhaseSI function which will return phase for given input - exposed to DLL
PropsSI can also return phase as double if "Phase" is the input

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>

src/AbstractState.cpp

@@ -262,6 +262,8 @@ double AbstractState::keyed_output(int key)
         return viscosity();
     case iconductivity:
         return conductivity();
+    case iPhase:
+        return phase();
     default:
         throw ValueError(format("This input [%d: \"%s\"] is not valid for keyed_output",key,get_parameter_information(key,"short").c_str()));
     }

src/CoolProp.cpp

@@ -31,7 +31,7 @@
 #include "Backends/Incompressible/IncompressibleLibrary.h"
 #include "Backends/Helmholtz/HelmholtzEOSBackend.h"
 #include "Backends/Helmholtz/MixtureParameters.h"
-
+#include "DataStructures.h"
 
 namespace CoolProp
 {
@@ -946,5 +946,42 @@ std::string get_fluid_param_string(std::string FluidName, std::string ParamName)
 		return(std::string("CoolProp error: Indeterminate error"));
 	}
 }
+std::string phase_lookup_string(phases Phase)
+{
+    switch (Phase)
+    {
+        case iphase_liquid: ///< Liquid
+            return "liquid";
+        case iphase_supercritical: ///< Supercritical (p > pc, T > Tc)
+            return "supercritical";
+        case iphase_supercritical_gas: ///< Supercritical gas (p < pc, T > Tc)
+            return "supercritical_gas";
+        case iphase_supercritical_liquid: ///< Supercritical liquid (p > pc, T < Tc)
+            return "supercritical_liquid";
+        case iphase_gas: ///< Subcritical gas
+            return "gas";
+        case iphase_twophase: ///< Twophase
+            return "twophase";
+        case iphase_unknown: ///< Unknown phase
+            return "unknown";
+        case iphase_not_imposed:
+            return "not_imposed";
+    }
+}
+std::string PhaseSI(const std::string &Name1, double Prop1, const std::string &Name2, double Prop2, const std::string &FluidName)
+{
+    double Phase_double = PropsSI("Phase",Name1,Prop1,Name2,Prop2,FluidName);
+    if (!ValidNumber(Phase_double)){ return "";}
+    std::size_t Phase_int = static_cast<std::size_t>(round(Phase_double));
+    return phase_lookup_string(static_cast<phases>(Phase_int));
+}
+    
+std::string PhaseSI(const std::string &Name1, double Prop1, const std::string &Name2, double Prop2, const std::string &FluidName, const std::vector<double> &z)
+{
+    double Phase_double = PropsSI("Phase",Name1,Prop1,Name2,Prop2,FluidName,z);
+    if (!ValidNumber(Phase_double)){ return "";}
+    std::size_t Phase_int = static_cast<std::size_t>(round(Phase_double));
+    return phase_lookup_string(static_cast<phases>(Phase_int));
+}
 
 } /* namespace CoolProp */

src/CoolPropLib.cpp

@@ -130,6 +130,14 @@ EXPORT_CODE double CONVENTION PropsSI(const char *Output, const char *Name1, dou
     std::string _Output = Output, _Name1 = Name1, _Name2 = Name2, _FluidName = FluidName;
     return CoolProp::PropsSI(_Output, _Name1, Prop1, _Name2, Prop2, _FluidName);
 }
+EXPORT_CODE long CONVENTION PhaseSI(const char *Output, const char *Name1, double Prop1, const char *Name2, double Prop2, const char * FluidName, char *phase)
+{
+    std::string _Name1 = Name1, _Name2 = Name2, _FluidName = FluidName;
+    std::string ph = CoolProp::PhaseSI(_Name1, Prop1, _Name2, Prop2, _FluidName);
+    if (ph.size() > strlen(phase)){
+        strcpy(phase, ph.c_str());
+    }
+}
 EXPORT_CODE double CONVENTION PropsSIZ(const char *Output, const char *Name1, double Prop1, const char *Name2, double Prop2, const char * FluidName, const double *z, int n)
 {
     std::string _Output = Output, _Name1 = Name1, _Name2 = Name2, _FluidName = FluidName;

src/DataStructures.cpp

@@ -85,6 +85,8 @@ parameter_info parameter_info_list[] = {
     parameter_info(idalpha0_dtau_constdelta, "dalpha0_dtau_constdelta","O","-","Derivative of ideal Helmholtz energy with tau",false),
     parameter_info(idalpha0_ddelta_consttau, "dalpha0_ddelta_consttau","O","-","Derivative of ideal Helmholtz energy with delta",false),
     
+    parameter_info(iPhase, "Phase","O","-","Phase index from \ref phases",false),
+    
 };
 
 class ParameterInformation