Generalize substitute_sample_time so that other backends and extend it

src/systems/clock_inference.jl

@@ -21,12 +21,12 @@
     ClockInference(ts, eq_domain, var_domain, inferred)
 end
 
 struct NotInferedTimeDomain end
 function error_sample_time(eq)
     error("$eq\ncontains `SampleTime` but it is not an infered discrete equation.")
 end
-function substitute_sample_time(ci::ClockInference)
-    @unpack ts, eq_domain = ci
+function substitute_sample_time(ci::ClockInference, ts::TearingState)
+    @unpack eq_domain = ci
     eqs = copy(equations(ts))
     @assert length(eqs) == length(eq_domain)
     for i in eachindex(eqs)
@@ -34,7 +34,7 @@
         domain = eq_domain[i]
         dt = sampletime(domain)
         neweq = substitute_sample_time(eq, dt)
         if neweq isa NotInferedTimeDomain
             error_sample_time(eq)
         end
         eqs[i] = neweq
@@ -52,13 +52,13 @@
     op = operation(ex)
     args = arguments(ex)
     if op == SampleTime
         dt === nothing && return NotInferedTimeDomain()
         return dt
     else
         new_args = similar(args)
         for (i, arg) in enumerate(args)
             ex_arg = substitute_sample_time(arg, dt)
             if ex_arg isa NotInferedTimeDomain
                 return ex_arg
             end
             new_args[i] = ex_arg
@@ -112,7 +112,7 @@
         end
     end
 
-    ci = substitute_sample_time(ci)
+    ci = substitute_sample_time(ci, ts)
     return ci
 end