simplify ldl configuration

src/solver/core/kktsolvers/direct/quasidef/ldlsolvers/config.rs

@@ -13,65 +13,24 @@ use crate::{
     },
 };
 
-// The Julia version implements the mapping from user setting
-// to LDL solver implementation using dynamic dispatch on
-// ::Val{:qdldl} types of arguments.   There is no equivalent
-// in Rust, so we get these big match statements.
-
 type LDLConstructor<T> =
     fn(&CscMatrix<T>, &[i8], &CoreSettings<T>, Option<Vec<usize>>) -> BoxedDirectLDLSolver<T>;
 
-// Some solvers only support 64 bit variants, which presents
-// a problem since most of the solver code is generic over FloatT
-// and trait specialization is not avaiable in Rust yet.   Hence
-// this janky trait
-
 pub trait LDLConfiguration: FloatT {
     fn get_ldlsolver_config(
         settings: &CoreSettings<Self>,
-    ) -> (MatrixTriangle, LDLConstructor<Self>) {
-        // default is to use the generic form, ignoring
-        // types that support f64 only
-        Self::get_ldlsolver_config_default(settings)
-    }
-
-    // The default configurator for generic T
-    fn get_ldlsolver_config_default(
-        settings: &CoreSettings<Self>,
-    ) -> (MatrixTriangle, LDLConstructor<Self>) {
-        let ldlptr: LDLConstructor<Self>;
-        let kktshape: MatrixTriangle;
-        let case = settings.direct_solve_method.as_str();
-
-        match case {
-            "auto" => {
-                kktshape = AutoDirectLDLSolver::<Self>::required_matrix_shape();
-                ldlptr = |M, D, S, P| AutoDirectLDLSolver::new(M, D, S, P);
-            }
-            "qdldl" => {
-                kktshape = QDLDLDirectLDLSolver::<Self>::required_matrix_shape();
-                ldlptr = |M, D, S, P| Box::new(QDLDLDirectLDLSolver::new(M, D, S, P));
-            }
-            #[cfg(feature = "faer-sparse")]
-            "faer" => {
-                kktshape = FaerDirectLDLSolver::<Self>::required_matrix_shape();
-                ldlptr = |M, D, S, P| Box::new(FaerDirectLDLSolver::new(M, D, S, P));
-            }
-            _ => {
-                panic!("Unrecognized LDL solver type: \"{}\"", case);
-            }
-        }
-        (kktshape, ldlptr)
-    }
+    ) -> (MatrixTriangle, LDLConstructor<Self>);
 }
 
-// This cursed section of code exists because trait specialisation
-// does not yet exist in rust.  We want get_ldlsolver_config to
-// construct pardiso solvers only when FloatT = f64, and to return
-// an error for pardiso options for all other FloatT.
+// The Julia version implements the mapping from user settings to LDL solver
+// implementation using dynamic dispatch on ::Val{:qdldl} types of arguments.
+// There is no equivalent in Rust, so we get these big match statemen
+
+// The implementation first handles the f64-specific solvers (MKL, Panua Pardiso).
+// Since trait specialization doesn't exist in Rust, we use runtime TypeId
+// checks within a blanket impl to conditionally enable these solvers only for f64.
 
 impl<T: FloatT> LDLConfiguration for T {
-    //
     fn get_ldlsolver_config(settings: &CoreSettings<T>) -> (MatrixTriangle, LDLConstructor<T>) {
         let ldlptr: LDLConstructor<T>;
         let kktshape: MatrixTriangle;
@@ -115,8 +74,23 @@ impl<T: FloatT> LDLConfiguration for T {
                     );
                 }
             }
-            _ => (kktshape, ldlptr) = Self::get_ldlsolver_config_default(settings),
-        }
+            "auto" => {
+                kktshape = AutoDirectLDLSolver::<T>::required_matrix_shape();
+                ldlptr = |M, D, S, P| AutoDirectLDLSolver::new(M, D, S, P);
+            }
+            "qdldl" => {
+                kktshape = QDLDLDirectLDLSolver::<T>::required_matrix_shape();
+                ldlptr = |M, D, S, P| Box::new(QDLDLDirectLDLSolver::new(M, D, S, P));
+            }
+            #[cfg(feature = "faer-sparse")]
+            "faer" => {
+                kktshape = FaerDirectLDLSolver::<T>::required_matrix_shape();
+                ldlptr = |M, D, S, P| Box::new(FaerDirectLDLSolver::new(M, D, S, P));
+            }
+            _ => {
+                panic!("Unrecognized LDL solver type: \"{}\"", case);
+            }
+        };
         (kktshape, ldlptr)
     }
 }