Sync public subset from Flux (private)

include/core/global_config.h

@@ -0,0 +1,36 @@
+#pragma once
+
+
+namespace core{
+
+    enum class GridKind { Uniform, NonUniform };
+    enum class FDKind   { Central, Forward, Backward };
+    enum class BCKind   { Dirichlet, Neumann /*, Robin*/ };
+    enum class SolverKind { LU, Inverse /*, CG*/ };
+
+    template <typename T>
+    struct BC { 
+        FDKind fd{FDKind::Forward};
+        BCKind kind{BCKind::Dirichlet}; 
+        T value{T(0)}; 
+    };
+
+
+    // Global default config holder
+    template <typename T>
+    struct Configs {
+        GridKind grid{GridKind::Uniform};
+        FDKind   fd{FDKind::Central};
+        BC<T>    left{FDKind::Forward, BCKind::Dirichlet, T(0) };
+        BC<T>    right{FDKind::Backward, BCKind::Dirichlet, T(0) };
+        SolverKind solver{SolverKind::LU};
+
+        static Configs& defaults() {
+            static Configs g{};   // process-wide defaults
+            return g;
+        }
+    };
+
+
+
+} // namespace core