[Cython] Add support for setting state using entropy + specifc volume

interfaces/cython/cantera/_cantera.pxd

@@ -98,6 +98,7 @@ cdef extern from "cantera/thermo/ThermoPhase.h" namespace "Cantera":
         void setState_HP(double, double) except +
         void setState_UV(double, double) except +
         void setState_SP(double, double) except +
+        void setState_SV(double, double) except +
 
         # molar thermodynamic properties:
         double enthalpy_mole() except +

interfaces/cython/cantera/test/test_thermo.py

@@ -150,6 +150,14 @@ class TestThermoPhase(utilities.CanteraTest):
         self.phase.SPX = s1, P1, X1
         check_state(T1, rho1, Y1)
 
+        self.phase.TDY = T0, rho0, Y0
+        self.phase.SVX = s1, v1, X1
+        check_state(T1, rho1, Y1)
+
+        self.phase.TDY = T0, rho0, Y0
+        self.phase.SVY = s1, v1, Y1
+        check_state(T1, rho1, Y1)
+
 
     def test_setState_mass(self):
         self.check_setters(T1 = 500.0, rho1 = 1.5,
@@ -175,6 +183,11 @@ class TestThermoPhase(utilities.CanteraTest):
         self.assertNear(U, self.phase.u)
         self.assertNear(V, self.phase.v)
 
+        S,V,X = self.phase.SVX
+        self.assertNear(S, self.phase.s)
+        self.assertNear(V, self.phase.v)
+        self.assertArrayNear(X, self.phase.X)
+
     def test_getState_mass(self):
         self.phase.TDY = 350.0, 0.7, 'H2:0.1, H2O2:0.1, AR:0.8'
         self.check_getters()

interfaces/cython/cantera/thermo.pyx

@@ -565,6 +565,39 @@ cdef class ThermoPhase(_SolutionBase):
             self.Y = values[2]
             self.SP = values[:2]
 
+    property SV:
+        """
+        Get/Set entropy [J/kg/K or J/kmol/K] and specific volume [m^3/kg or
+        m^3/kmol].
+        """
+        def __get__(self):
+            return self.s, self.v
+        def __set__(self, values):
+            self.thermo.setState_SV(values[0] / self._mass_factor(),
+                                    values[1] / self._mass_factor())
+
+    property SVX:
+        """
+        Get/Set entropy [J/kg/K or J/kmol/K], specific volume [m^3/kg or
+        m^3/kmol], and mole fractions.
+        """
+        def __get__(self):
+            return self.s, self.v, self.X
+        def __set__(self, values):
+            self.X = values[2]
+            self.SV = values[:2]
+
+    property SVY:
+        """
+        Get/Set entropy [J/kg/K or J/kmol/K], specific volume [m^3/kg or
+        m^3/kmol], and mass fractions.
+        """
+        def __get__(self):
+            return self.s, self.v, self.Y
+        def __set__(self, values):
+            self.Y = values[2]
+            self.SV = values[:2]
+
     # partial molar / non-dimensional properties
     property partial_molar_enthalpies:
         """Array of species partial molar enthalpies [J/kmol]."""