Add getindex/setindex! methods for MTKParameters with ParameterIndex

Author: MasonProtter

src/systems/parameter_buffer.jl

@@ -361,6 +361,41 @@ function Base.setindex!(p::MTKParameters, val, i)
     end
 end
 
+function Base.getindex(p::MTKParameters, pind::ParameterIndex)
+    (;portion, idx) = pind, (i,j) = idx
+    if portion isa SciMLStructures.Tunable
+        p.tunable[i][j]
+    elseif portion isa SciMLStructures.Discrete
+        p.discrete[i][j]
+    elseif portion isa SciMLStructures.Constants
+        p.constant[i][j]
+    elseif portion === DEPENDENT_PORTION
+        p.dependent[i][j]
+    elseif portion === NONNUMERIC_PORTION
+        p.nonnumeric[i][j]
+    else
+        error("Unhandled portion $portion")
+    end
+end
+
+function Base.setindex!(p::MTKParameters, val, pind::ParameterIndex)
+    (;portion, idx) = pind
+    (i,j) = idx
+    if portion isa SciMLStructures.Tunable
+        p.tunable[i][j] = val
+    elseif portion isa SciMLStructures.Discrete
+        p.discrete[i][j] = val
+    elseif portion isa SciMLStructures.Constants
+        p.constant[i][j] = val
+    elseif portion === DEPENDENT_PORTION
+        p.dependent[i][j] = val
+    elseif portion === NONNUMERIC_PORTION
+        p.nonnumeric[i][j] = val
+    else
+        error("Unhandled portion $portion")
+    end
+end
+
 function Base.iterate(buf::MTKParameters, state = 1)
     total_len = 0
     total_len += _num_subarrays(buf.tunable)