fixup! refactor: rework discrete indexing behavior

src/state_indexing.jl

@@ -157,6 +157,9 @@ end
 function is_indexer_timeseries(::Type{G}) where {G <: MultipleGetters{<:Vector}}
     return IndexerMixedTimeseries()
 end
+function is_indexer_timeseries(::Type{G}) where {G <: MultipleGetters{Nothing}}
+    return IndexerNotTimeseries()
+end
 
 function (mg::MultipleGetters)(ts::IsTimeseriesTrait, prob, args...)
     return mg(ts, is_indexer_timeseries(mg), prob, args...)
@@ -180,7 +183,7 @@ end
 function (mg::MultipleGetters)(ts::Timeseries, ::IndexerBoth, prob, i)
     mg.((ts,), (prob,), i)
 end
-function (mg::MultipleGetters)(::NotTimeseries, ::IndexerBoth, prob)
+function (mg::MultipleGetters)(::NotTimeseries, ::Union{IndexerBoth, IndexerNotTimeseries}, prob)
     return map(g -> g(prob), mg.getters)
 end
 
@@ -222,6 +225,19 @@ for (t1, t2) in [
             return MultipleGetters(ContinuousTimeseries(), sym)
         end
         sym_arr = sym isa Tuple ? collect(sym) : sym
+        num_observed = count(x -> is_observed(sys, x), sym)
+        if !is_time_dependent(sys)
+            if num_observed == 0 || num_observed == 1 && sym isa Tuple
+                return MultipleGetters(nothing, getu.((sys,), sym))
+            else
+                obs = observed(sys, sym_arr)
+                getter = TimeIndependentObservedFunction(obs)
+                if sym isa Tuple
+                    getter = AsTupleWrapper{length(sym)}(getter)
+                end
+                return getter
+            end
+        end
         ts_idxs = get_all_timeseries_indexes(sys, sym_arr)
         if !(ContinuousTimeseries() in ts_idxs)
             return getp(sys, sym)

test/parameter_indexing_test.jl

@@ -3,8 +3,7 @@ using SymbolicIndexingInterface: IndexerOnlyTimeseries, IndexerNotTimeseries, In
                                  IndexerMixedTimeseries,
                                  is_indexer_timeseries, indexer_timeseries_index,
                                  ParameterTimeseriesValueIndexMismatchError,
-                                 MixedParameterTimeseriesIndexError,
-                                 MixedContinuousParameterTimeseriesError
+                                 MixedParameterTimeseriesIndexError
 using Test
 
 arr = [1.0, 2.0, 3.0]
@@ -465,14 +464,29 @@ for (sym, val_is_timeseries, val, check_inference) in [
     end
 end
 
-for sym in [
-    [:x, :b],
-    (:x, :c),
-    :(x + b),
-    [:(2b), :(3x)],
-    (:(2b), :(3x))
+temp_state = ProblemState(; u = fs.u[1],
+    p = with_updated_parameter_timeseries_values(
+        parameter_values(fs), 1 => fs.p_ts[1, 1], 2 => fs.p_ts[2, 1]),
+    t = fs.t[1])
+_xval = temp_state.u[1]
+_bval = bval[1]
+_cval = cval[1]
+for (sym, val, check_inference) in [
+    ([:x, :b], [_xval, _bval], false),
+    ((:x, :c), (_xval, _cval), true),
+    (:(x + b), _xval + _bval, true),
+    ([:(2b), :(3x)], [2_bval, 3_xval], true),
+    ((:(2b), :(3x)), (2_bval, 3_xval), true)
 ]
-    @test_throws MixedContinuousParameterTimeseriesError getu(sys, sym)
+    getter = getu(sys, sym)
+    @test_throws MixedParameterTimeseriesIndexError getter(fs)
+    for subidx in [1, CartesianIndex(2), :, rand(Bool, 4), rand(1:4, 3), 1:2]
+        @test_throws MixedParameterTimeseriesIndexError getter(fs, subidx)
+    end
+    if check_inference
+        @inferred getter(temp_state)
+    end
+    @test getter(temp_state) == val
 end
 
 for sym in [