handle new operator in shift_discrete_system

Author: baggepinnen

src/systems/systemstructure.jl

@@ -457,23 +457,24 @@ function lower_order_var(dervar, t)
 end
 
 function shift_discrete_system(ts::TearingState)
+    dops = Union{Sample, Hold, ClockChange}
     @unpack fullvars, sys = ts
     discvars = OrderedSet()
     eqs = equations(sys)
     for eq in eqs
-        vars!(discvars, eq; op = Union{Sample, Hold})
+        vars!(discvars, eq; op = dops)
     end
     iv = get_iv(sys)
     discmap = Dict(k => StructuralTransformations.simplify_shifts(Shift(iv, 1)(k))
     for k in discvars
-    if any(isequal(k), fullvars) && !isa(operation(k), Union{Sample, Hold}))
+    if any(isequal(k), fullvars) && !isa(operation(k), dops))
     for i in eachindex(fullvars)
         fullvars[i] = StructuralTransformations.simplify_shifts(fast_substitute(
-            fullvars[i], discmap; operator = Union{Sample, Hold}))
+            fullvars[i], discmap; operator = dops))
     end
     for i in eachindex(eqs)
         eqs[i] = StructuralTransformations.simplify_shifts(fast_substitute(
-            eqs[i], discmap; operator = Union{Sample, Hold}))
+            eqs[i], discmap; operator = dops))
     end
     @set! ts.sys.eqs = eqs
     @set! ts.fullvars = fullvars

test/clock.jl

@@ -549,3 +549,25 @@ end
 @mtkbuild cc = CC()
 prob = ODEProblem(cc, [], (0, 10))
 sol = solve(prob, Tsit5(); kwargshandle = KeywordArgSilent)
+d1 = reduce(vcat, sol.prob.kwargs[:disc_saved_values][1].saveval)
+d2 = reduce(vcat, sol.prob.kwargs[:disc_saved_values][2].saveval)
+
+if length(d1) < length(d2)
+    d1, d2 = d2, d1
+end
+
+@test d2 == 1:6 # y
+
+X = [0, 0] # xy
+ti = 0
+for ti in 0:10
+    i = ti + 1
+    x, y = X
+    if ti % 2 == 0
+        y = y + 1
+    end
+    x = x + y
+
+    @test d1[i] == x
+    X = [x, y]
+end