refactor: make symbol_to_symbolic a global utility function

Author: AayushSabharwal

src/systems/diffeqs/odesystem.jl

@@ -445,20 +445,10 @@ function build_explicit_observed_function(sys, ts;
     end
 
     allsyms = all_symbols(sys)
-    function symbol_to_symbolic(sym)
-        sym isa Symbol || return sym
-        idx = findfirst(x -> (hasname(x) ? getname(x) : Symbol(x)) == sym, allsyms)
-        idx === nothing && return sym
-        sym = allsyms[idx]
-        if iscall(sym) && operation(sym) == getindex
-            sym = arguments(sym)[1]
-        end
-        return sym
-    end
     if symbolic_type(ts) == NotSymbolic() && ts isa AbstractArray
-        ts = map(symbol_to_symbolic, ts)
+        ts = map(x -> symbol_to_symbolic(sys, x; allsyms), ts)
     else
-        ts = symbol_to_symbolic(ts)
+        ts = symbol_to_symbolic(sys, ts; allsyms)
     end
 
     vs = ModelingToolkit.vars(ts; op)

src/utils.jl

@@ -1249,3 +1249,21 @@ function process_equations(eqs, iv)
 
     diffvars, allunknowns, ps, Equation[diffeq; algeeq; compressed_eqs]
 end
+
+"""
+    $(TYPEDSIGNATURES)
+
+If `sym isa Symbol`, try and convert it to a symbolic by matching against symbolic
+variables in `allsyms`. If `sym` is not a `Symbol` or no match was found, return
+`sym` as-is.
+"""
+function symbol_to_symbolic(sys::AbstractSystem, sym; allsyms = all_symbols(sys))
+    sym isa Symbol || return sym
+    idx = findfirst(x -> (hasname(x) ? getname(x) : Symbol(x)) == sym, allsyms)
+    idx === nothing && return sym
+    sym = allsyms[idx]
+    if iscall(sym) && operation(sym) == getindex
+        sym = arguments(sym)[1]
+    end
+    return sym
+end