better default constructors in the weird cases

Author: ChrisRackauckas

src/utils.jl

@@ -33,6 +33,8 @@ function flatten_expr!(x)
     x
 end
 
+default_tensor_constructor(x) = x->(out = similar(typeof(u),$(size(rhss)...)); out .= x)
+
 function build_function(rhss, vs, ps = (), args = (), conv = simplified_expr, expression = Val{true};
                         checkbounds = false, constructor=nothing, linenumbers = true)
     _vs = map(x-> x isa Operation ? x.op : x, vs)
@@ -59,11 +61,11 @@ function build_function(rhss, vs, ps = (), args = (), conv = simplified_expr, ex
     if rhss isa Matrix
         arr_sys_expr = build_expr(:vcat, [build_expr(:row,[conv(rhs) for rhs ∈ rhss[i,:]]) for i in 1:size(rhss,1)])
         # : x because ??? what to do in the general case?
-        _constructor = constructor === nothing ? :(u isa ModelingToolkit.StaticArrays.StaticArray ? ModelingToolkit.StaticArrays.SMatrix{$(size(rhss)...)} : x->x) : constructor
+        _constructor = constructor === nothing ? :(u isa ModelingToolkit.StaticArrays.StaticArray ? ModelingToolkit.StaticArrays.SMatrix{$(size(rhss)...)} : default_tensor_constructor) : constructor
     elseif typeof(rhss) <: Array && !(typeof(rhss) <: Vector)
         vector_form = build_expr(:vect, [conv(rhs) for rhs ∈ rhss])
         arr_sys_expr = :(reshape($vector_form,$(size(rhss)...)))
-        _constructor = constructor === nothing ? :(u isa ModelingToolkit.StaticArrays.StaticArray ? ModelingToolkit.StaticArrays.SArray{$(size(rhss)...)} : x->x) : constructor
+        _constructor = constructor === nothing ? :(u isa ModelingToolkit.StaticArrays.StaticArray ? ModelingToolkit.StaticArrays.SArray{$(size(rhss)...)} : default_tensor_constructor) : constructor
     elseif rhss isa SparseMatrixCSC
         vector_form = build_expr(:vect, [conv(rhs) for rhs ∈ nonzeros(rhss)])
         arr_sys_expr = :(SparseMatrixCSC{eltype(u),Int}($(size(rhss)...), $(rhss.colptr), $(rhss.rowval), $vector_form))
@@ -85,15 +87,16 @@ function build_function(rhss, vs, ps = (), args = (), conv = simplified_expr, ex
 
     oop_ex = :(
         ($(fargs.args...),) -> begin
-            if $(fargs.args[1]) isa Array
+            # If u is a weird non-StaticArray type and we want a sparse matrix, just do the optimized sparse anyways
+            if $(fargs.args[1]) isa Array || (!($(fargs.args[1]) <: StaticArray) && $(rhss isa SparseMatrixCSC))
                 return $arr_bounds_block
             else
                 X = $bounds_block
+                T = promote_type(map(typeof,X)...)
+                map(T,X)
+                construct = $_constructor
+                return construct(X)
             end
-            T = promote_type(map(typeof,X)...)
-            map(T,X)
-            construct = $_constructor
-            construct(X)
         end
     )