add StructIO

src/Blocks/Blocks.jl

@@ -11,6 +11,7 @@ using ModelingToolkit: getdefault
 D = Differential(t)
 
 export RealInput, RealOutput, SISO
+using Symbolics: Struct, StructElement, getelements, symstruct
 include("utils.jl")
 
 export Gain, Sum, MatrixGain, Feedback, Add, Add3, Product, Division

src/Blocks/utils.jl

@@ -107,3 +107,40 @@ Base class for a multiple input multiple output (MIMO) continuous system block.
     ]
     return ODESystem(eqs, t, vcat(u..., y...), []; name = name, systems = [input, output])
 end
+
+
+
+using Symbolics: Struct, symbolic_getproperty
+@connector function StructInput(; structdef, name)
+    @variables u(t)::Struct [input = true] # Dummy default value due to bug in Symbolics
+    ODESystem(Equation[], t, [u], []; name)
+end
+
+@connector function StructOutput(; structdef, name)
+    @variables u(t)::Struct [output = true] # Dummy default value due to bug in Symbolics
+    ODESystem(Equation[], t, [u], []; name)
+end
+
+function _structelem2connector(elem::StructElement)
+    T = Symbolics.decodetyp(elem.typ)
+    if T <: Bool
+        return BoolOutput(; name = elem.name)
+    elseif T <: Real
+        return RealOutput(; name = elem.name)
+    end
+end
+
+@component function BusSelect(;name, structdef, selected_fields)
+    @parameters t
+    nout = length(selected_fields)
+    inputbus = Blocks.StructInput(; structdef, name = Symbol("inputbus"))
+    @variables input(t)
+
+    output_elements = filter(e->e.name in selected_fields, getelements(structdef))
+    output_connectors = map(_structelem2connector, output_elements)
+
+    eqs = [
+        symbolic_getproperty(inputbus.u, field) ~ con.u for (field, con) in zip(selected_fields, output_connectors)
+    ]
+    return ODESystem(eqs, t; name = name, systems = [inputbus; output_connectors])
+end

test/Blocks/sources.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, ModelingToolkitStandardLibrary, OrdinaryDiffEq
+using ModelingToolkit, ModelingToolkitStandardLibrary, OrdinaryDiffEq, Test
 using ModelingToolkitStandardLibrary.Blocks
 using ModelingToolkitStandardLibrary.Blocks: smooth_sin, smooth_cos, smooth_damped_sin,
     smooth_square, smooth_step, smooth_ramp,
@@ -474,3 +474,58 @@ end
         @test sol[ddy][end]≈2 atol=1e-3
     end
 end
+
+using Symbolics
+using Symbolics: Struct, StructElement, getelements, symstruct
+using Test
+using ModelingToolkitStandardLibrary.Blocks
+using ModelingToolkitStandardLibrary.Blocks: BusSelect
+#using ModelingToolkitStandardLibrary.Blocks: structelem2connector
+
+# Test struct
+struct BarStruct
+    speed::Float64
+    isSpeedValid::Int
+end
+
+bar = BarStruct(2.0, 1)
+structdef = symstruct(BarStruct)
+selected_fields = [:speed]
+
+@parameters bar_param::Struct
+systems = @named begin
+    inputbus = Blocks.StructOutput(; structdef)
+    output = BusSelect(; structdef, selected_fields)
+end
+eqs = [inputbus.u ~ bar_param
+       connect(inputbus, output.inputbus)]
+@named sys = ODESystem(eqs, t; systems)
+sys = complete(sys)
+ssys = structural_simplify(sys)
+prob = ODEProblem(ssys, [], (0.0, 1.0), [sys.bar_param => bar], tofloat=false)
+sol = solve(prob, Rodas4())
+@test sol(1.0, idxs = sys.output.speed.u) == 2.0
+
+@mtkmodel BusSelectTest begin
+    @parameters bar_param::Struct
+    @components begin
+        inputbus = Blocks.StructOutput(; structdef)
+        output = BusSelect(; structdef, selected_fields)
+    end
+    @equations begin
+        inputbus.u ~ bar_param
+        connect(inputbus, output.inputbus)
+    end
+end
+
+@named sys = BusSelectTest()
+sys = complete(sys)
+ssys = structural_simplify(sys)
+@test_broken begin
+    prob = ODEProblem(ssys, [
+                             sys.bar_param => bar
+                            ], (0.0, 1.0))
+    sol = solve(prob, Rodas4())
+    @test sol.retcode == ReturnCode.Success
+    @test sol(1.0, idxs = sys.output.speed.u) == 2.0
+end