wip: add StructIO

src/Blocks/utils.jl

@@ -107,3 +107,41 @@ 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
+
+
+
+@connector function StructInput(; structdef, name)
+    n = Symbolics.juliatype(structdef)
+    @variables u(t)::n [input = true] # Dummy default value due to bug in Symbolics
+    ODESystem(Equation[], t, [u], []; name)
+end
+
+@connector function StructOutput(; structdef, name)
+    n = Symbolics.juliatype(structdef)
+    @variables u(t)::n [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 = [
+        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

@@ -474,3 +474,32 @@ 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: structelem2connector
+
+# Test struct
+struct BarStruct
+    speed::Float64
+    isSpeedValid::Int
+end
+
+bar = BarStruct(1.0, 1)
+structdef = symstruct(BarStruct)
+selected_fields = [:speed]
+
+@mtkmodel BusSelectTest begin
+    @components begin
+        inputbus = Blocks.StructOutput(; structdef)
+        output = BusSelect(; structdef, selected_fields)
+    end
+    @equations begin
+        inputbus.u ~ bar
+        connect(inputbus, output)
+    end
+end
+
+@named sys = BusSelectTest()