Throw an error if structural simplification is applied twice

Author: YingboMa

src/structural_transformation/StructuralTransformations.jl

@@ -24,7 +24,7 @@ using ModelingToolkit: ODESystem, AbstractSystem, var_from_nested_derivative, Di
                        invalidate_cache!, Substitutions, get_or_construct_tearing_state,
                        filter_kwargs, lower_varname, setio, SparseMatrixCLIL,
                        get_fullvars, has_equations, observed,
-                       Schedule
+                       Schedule, schedule
 
 using ModelingToolkit.BipartiteGraphs
 import .BipartiteGraphs: invview, complete

src/structural_transformation/symbolics_tearing.jl

@@ -615,6 +615,7 @@ function tearing_reassemble(state::TearingState, var_eq_matching,
     if sys isa ODESystem
         @set! sys.schedule = Schedule(var_eq_matching, dummy_sub)
     end
+    sys = schedule(sys)
     @set! state.sys = sys
     @set! sys.tearing_state = state
     return invalidate_cache!(sys)

src/systems/abstractsystem.jl

@@ -846,6 +846,19 @@ end
 
 iscomplete(sys::AbstractSystem) = isdefined(sys, :complete) && getfield(sys, :complete)
 
+function schedule(sys::AbstractSystem)
+    has_schedule(sys) ? sys : (@set! sys.isscheduled = true)
+end
+function isscheduled(sys::AbstractSystem)
+    if has_schedule(sys)
+        get_schedule(sys) !== nothing
+    elseif has_isscheduled(sys)
+        get_isscheduled(sys)
+    else
+        false
+    end
+end
+
 """
 $(TYPEDSIGNATURES)
 
@@ -907,7 +920,8 @@ for prop in [:eqs
              :split_idxs
              :parent
              :index_cache
-             :is_scalar_noise]
+             :is_scalar_noise
+             :isscheduled]
     fname_get = Symbol(:get_, prop)
     fname_has = Symbol(:has_, prop)
     @eval begin

src/systems/diffeqs/sdesystem.jl

@@ -133,13 +133,15 @@ struct SDESystem <: AbstractODESystem
     be `true` when `noiseeqs isa Vector`. 
     """
     is_scalar_noise::Bool
+    isscheduled::Bool
 
     function SDESystem(tag, deqs, neqs, iv, dvs, ps, tspan, var_to_name, ctrls, observed,
             tgrad,
             jac,
             ctrl_jac, Wfact, Wfact_t, name, systems, defaults, connector_type,
             cevents, devents, parameter_dependencies, metadata = nothing, gui_metadata = nothing,
-            complete = false, index_cache = nothing, parent = nothing, is_scalar_noise = false;
+            complete = false, index_cache = nothing, parent = nothing, is_scalar_noise = false,
+            isscheduled = false;
             checks::Union{Bool, Int} = true)
         if checks == true || (checks & CheckComponents) > 0
             check_independent_variables([iv])
@@ -162,7 +164,8 @@ struct SDESystem <: AbstractODESystem
         new(tag, deqs, neqs, iv, dvs, ps, tspan, var_to_name, ctrls, observed, tgrad, jac,
             ctrl_jac,
             Wfact, Wfact_t, name, systems, defaults, connector_type, cevents, devents,
-            parameter_dependencies, metadata, gui_metadata, complete, index_cache, parent, is_scalar_noise)
+            parameter_dependencies, metadata, gui_metadata, complete, index_cache, parent, is_scalar_noise,
+            isscheduled)
     end
 end
 

src/systems/discrete_system/discrete_system.jl

@@ -91,14 +91,16 @@ struct DiscreteSystem <: AbstractTimeDependentSystem
     The hierarchical parent system before simplification.
     """
     parent::Any
+    isscheduled::Bool
 
     function DiscreteSystem(tag, discreteEqs, iv, dvs, ps, tspan, var_to_name,
             observed,
             name,
             systems, defaults, preface, connector_type, parameter_dependencies = Equation[],
             metadata = nothing, gui_metadata = nothing,
             tearing_state = nothing, substitutions = nothing,
-            complete = false, index_cache = nothing, parent = nothing;
+            complete = false, index_cache = nothing, parent = nothing,
+            isscheduled = false;
             checks::Union{Bool, Int} = true)
         if checks == true || (checks & CheckComponents) > 0
             check_independent_variables([iv])
@@ -113,7 +115,7 @@ struct DiscreteSystem <: AbstractTimeDependentSystem
             systems,
             defaults,
             preface, connector_type, parameter_dependencies, metadata, gui_metadata,
-            tearing_state, substitutions, complete, index_cache, parent)
+            tearing_state, substitutions, complete, index_cache, parent, isscheduled)
     end
 end
 

src/systems/jumps/jumpsystem.jl

@@ -114,12 +114,13 @@ struct JumpSystem{U <: ArrayPartition} <: AbstractTimeDependentSystem
     Cached data for fast symbolic indexing.
     """
     index_cache::Union{Nothing, IndexCache}
+    isscheduled::Bool
 
     function JumpSystem{U}(tag, ap::U, iv, unknowns, ps, var_to_name, observed, name,
             systems,
             defaults, connector_type, devents, parameter_dependencies,
             metadata = nothing, gui_metadata = nothing,
-            complete = false, index_cache = nothing;
+            complete = false, index_cache = nothing, isscheduled = false;
             checks::Union{Bool, Int} = true) where {U <: ArrayPartition}
         if checks == true || (checks & CheckComponents) > 0
             check_independent_variables([iv])
@@ -132,7 +133,7 @@ struct JumpSystem{U <: ArrayPartition} <: AbstractTimeDependentSystem
         end
         new{U}(tag, ap, iv, unknowns, ps, var_to_name, observed, name, systems, defaults,
             connector_type, devents, parameter_dependencies, metadata, gui_metadata,
-            complete, index_cache)
+            complete, index_cache, isscheduled)
     end
 end
 function JumpSystem(tag, ap, iv, states, ps, var_to_name, args...; kwargs...)

src/systems/nonlinear/nonlinearsystem.jl

@@ -89,21 +89,22 @@ struct NonlinearSystem <: AbstractTimeIndependentSystem
     The hierarchical parent system before simplification.
     """
     parent::Any
+    isscheduled::Bool
 
     function NonlinearSystem(tag, eqs, unknowns, ps, var_to_name, observed, jac, name,
             systems,
             defaults, connector_type, parameter_dependencies = Equation[], metadata = nothing,
             gui_metadata = nothing,
             tearing_state = nothing, substitutions = nothing,
-            complete = false, index_cache = nothing, parent = nothing; checks::Union{
-                Bool, Int} = true)
+            complete = false, index_cache = nothing, parent = nothing,
+            isscheduled = false; checks::Union{Bool, Int} = true)
         if checks == true || (checks & CheckUnits) > 0
             u = __get_unit_type(unknowns, ps)
             check_units(u, eqs)
         end
         new(tag, eqs, unknowns, ps, var_to_name, observed, jac, name, systems, defaults,
             connector_type, parameter_dependencies, metadata, gui_metadata, tearing_state,
-            substitutions, complete, index_cache, parent)
+            substitutions, complete, index_cache, parent, isscheduled)
     end
 end
 

src/systems/optimization/optimizationsystem.jl

@@ -64,10 +64,12 @@ struct OptimizationSystem <: AbstractOptimizationSystem
     The hierarchical parent system before simplification.
     """
     parent::Any
+    isscheduled::Bool
 
     function OptimizationSystem(tag, op, unknowns, ps, var_to_name, observed,
             constraints, name, systems, defaults, metadata = nothing,
-            gui_metadata = nothing, complete = false, index_cache = nothing, parent = nothing;
+            gui_metadata = nothing, complete = false, index_cache = nothing, parent = nothing,
+            isscheduled = false;
             checks::Union{Bool, Int} = true)
         if checks == true || (checks & CheckUnits) > 0
             u = __get_unit_type(unknowns, ps)
@@ -77,7 +79,7 @@ struct OptimizationSystem <: AbstractOptimizationSystem
         end
         new(tag, op, unknowns, ps, var_to_name, observed,
             constraints, name, systems, defaults, metadata, gui_metadata, complete,
-            index_cache, parent)
+            index_cache, parent, isscheduled)
     end
 end
 

src/systems/systems.jl

@@ -3,6 +3,14 @@ function System(eqs::AbstractVector{<:Equation}, iv, args...; name = nothing,
     ODESystem(eqs, iv, args...; name, kw..., checks = false)
 end
 
+const REPEATED_SIMPLIFICATION_MESSAGE = "Structural simplification cannot be applied to a completed system. Double simplification is not allowed."
+
+struct RepeatedStructuralSimplificationError <: Exception end
+
+function Base.showerror(io::IO, e::RepeatedStructuralSimplificationError)
+    print(io, REPEATED_SIMPLIFICATION_MESSAGE)
+end
+
 """
 $(SIGNATURES)
 
@@ -21,6 +29,7 @@ function structural_simplify(
         sys::AbstractSystem, io = nothing; simplify = false, split = true,
         allow_symbolic = false, allow_parameter = true, conservative = false, fully_determined = true,
         kwargs...)
+    isscheduled(sys) && throw(RepeatedStructuralSimplificationError())
     newsys′ = __structural_simplify(sys, io; simplify,
         allow_symbolic, allow_parameter, conservative, fully_determined,
         kwargs...)

test/components.jl

@@ -44,6 +44,7 @@ completed_rc_model = complete(rc_model)
 @test ModelingToolkit.n_extra_equations(capacitor) == 2
 @test length(equations(structural_simplify(rc_model, allow_parameter = false))) == 2
 sys = structural_simplify(rc_model)
+@test_throws ModelingToolkit.RepeatedStructuralSimplificationError structural_simplify(sys)
 @test length(equations(sys)) == 1
 check_contract(sys)
 @test !isempty(ModelingToolkit.defaults(sys))