From bc115557dc45d62392e4e0ac7e55963bfef14e22 Mon Sep 17 00:00:00 2001
From: Joshua Lampert <51029046+JoshuaLampert@users.noreply.github.com>
Date: Wed, 13 Dec 2023 18:54:07 +0100
Subject: [PATCH] introduce type parameters in solver (#77)

---
 src/solver.jl | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/solver.jl b/src/solver.jl
index 1bc2d645..6070ac19 100644
--- a/src/solver.jl
+++ b/src/solver.jl
@@ -10,13 +10,19 @@ abstract type AbstractSolver end
 
 A `struct` that holds the summation by parts (SBP) operators that are used for the spatial discretization.
 """
-struct Solver{RealT <: Real} <: AbstractSolver
-    D1::AbstractDerivativeOperator{RealT}
-    D2::Union{AbstractDerivativeOperator{RealT}, AbstractMatrix{RealT}}
-
-    function Solver{RealT}(D1::AbstractDerivativeOperator{RealT},
-                           D2::Union{AbstractDerivativeOperator{RealT},
-                                     AbstractMatrix{RealT}}) where {RealT}
+struct Solver{RealT <: Real, FirstDerivative <: AbstractDerivativeOperator{RealT},
+              SecondDerivative <:
+              Union{AbstractDerivativeOperator{RealT}, AbstractMatrix{RealT}}} <:
+       AbstractSolver
+    D1::FirstDerivative
+    D2::SecondDerivative
+
+    function Solver{RealT, FirstDerivative, SecondDerivative}(D1::FirstDerivative,
+                                                              D2::SecondDerivative) where {
+                                                                                           RealT,
+                                                                                           FirstDerivative,
+                                                                                           SecondDerivative
+                                                                                           }
         @assert derivative_order(D1) == 1
         if D2 isa AbstractDerivativeOperator
             @assert derivative_order(D2) == 2
@@ -35,7 +41,7 @@ function Solver(mesh, accuracy_order)
     D1 = periodic_derivative_operator(1, accuracy_order, mesh.xmin, mesh.xmax, mesh.N)
     D2 = periodic_derivative_operator(2, accuracy_order, mesh.xmin, mesh.xmax, mesh.N)
     @assert real(D1) == real(D2)
-    Solver{real(D1)}(D1, D2)
+    Solver{real(D1), typeof(D1), typeof(D2)}(D1, D2)
 end
 
 # Also allow to pass custom SBP operators (for convenience without explicitly specifying the type)
@@ -50,7 +56,7 @@ function Solver(D1::AbstractDerivativeOperator{RealT},
                 D2::Union{AbstractDerivativeOperator{RealT}, AbstractMatrix{RealT}}) where {
                                                                                             RealT
                                                                                             }
-    Solver{RealT}(D1, D2)
+    Solver{RealT, typeof(D1), typeof(D2)}(D1, D2)
 end
 
 function Base.show(io::IO, solver::Solver{RealT}) where {RealT}