feat: add new all-symbols methods from SII

Author: AayushSabharwal

Project.toml

@@ -98,7 +98,7 @@ SimpleNonlinearSolve = "0.1.0, 1"
 SparseArrays = "1"
 SpecialFunctions = "0.7, 0.8, 0.9, 0.10, 1.0, 2"
 StaticArrays = "0.10, 0.11, 0.12, 1.0"
-SymbolicIndexingInterface = "0.3"
+SymbolicIndexingInterface = "0.3.1"
 SymbolicUtils = "1.0"
 Symbolics = "5.7"
 URIs = "1"

src/systems/abstractsystem.jl

@@ -286,6 +286,20 @@ SymbolicIndexingInterface.is_time_dependent(::AbstractTimeIndependentSystem) = f
 
 SymbolicIndexingInterface.constant_structure(::AbstractSystem) = true
 
+function SymbolicIndexingInterface.all_variable_symbols(sys::AbstractSystem)
+    syms = variable_symbols(sys)
+    obs = getproperty.(observed(sys), :lhs)
+    return isempty(obs) ? syms : vcat(syms, obs)
+end
+
+function SymbolicIndexingInterface.all_symbols(sys::AbstractSystem)
+    syms = all_variable_symbols(sys)
+    for other in (parameter_symbols(sys), independent_variable_symbols(sys))
+        isempty(other) || (syms = vcat(syms, other))
+    end
+    return syms
+end
+
 iscomplete(sys::AbstractSystem) = isdefined(sys, :complete) && getfield(sys, :complete)
 
 """