WIP: Add plan type to python interface

pypocketfft.cc

@@ -38,6 +38,55 @@ using f64 = double;
 using flong = ldbl_t;
 auto None = py::none();
 
+enum class transform_type : unsigned char
+  {
+  c2c,
+  rc,
+  r2r,
+  dct,
+  dst
+  };
+
+enum class data_type : unsigned char
+	{
+	flt, dbl, ldbl
+	};
+
+struct plan
+	{
+	transform_type ttype_;
+	data_type dtype_;
+	shared_ptr<void> plan_;
+	};
+
+template <typename T> struct type_enum;
+template <> struct type_enum<float> :
+		integral_constant<data_type, data_type::flt> {};
+template <> struct type_enum<double> :
+		integral_constant<data_type, data_type::dbl> {};
+template <> struct type_enum<long double> :
+		integral_constant<data_type, data_type::ldbl> {};
+
+template <typename T> struct plan_caster;
+template <typename T> struct plan_caster<c2c_plan_t<T>>
+	{
+	static shared_ptr<c2c_plan_t<T>> cast (const plan &plan)
+			{
+			if (plan->ttype_ != transform_type::c2c)
+				throw invalid_argument("wrong type of plan");
+
+			if (plan->dtype_ != type_enum<T>::value)
+				throw invalid_argument("plan is for wrong dtype");
+
+			return reinterpret_pointer_cast<c2c_plan_t<T>>(plan->plan_);
+			}
+	};
+
+template <typename T> plan_cast(const plan &plan)
+	{
+	return plan_caster<T>::cast(plan);
+	}
+
 shape_t copy_shape(const py::array &arr)
   {
   shape_t res(size_t(arr.ndim()));