Merge pull request #90 from SciML/as/symcontainer-recursive

fix: fix stack overflow for methods using `symbolic_container` to define a fallback

Author: AayushSabharwal

docs/src/api.md

@@ -5,7 +5,6 @@
 ### Mandatory methods
 
 ```@docs
-symbolic_container
 is_variable
 variable_index
 variable_symbols
@@ -26,6 +25,10 @@ allvariables
 
 ### Optional Methods
 
+```@docs
+symbolic_container
+```
+
 #### Observed equation handling
 
 ```@docs

src/index_provider_interface.jl

@@ -5,6 +5,11 @@ Using `indp`, return an object that implements the index provider interface. In
 itself implements the interface, `indp` can be returned as-is. All index provider interface
 methods fall back to calling the same method on `symbolic_container(indp)`, so this may be
 used for trivial implementations of the interface that forward all calls to another object.
+
+Note that this method is optional. Thus the correct method to check for a fallback is:
+```julia
+hasmethod(symbolic_container, Tuple{typeof(indp)}) && symbolic_container(indp) != indp
+```
 """
 function symbolic_container end
 
@@ -59,8 +64,9 @@ parameter_index(indp, sym) = parameter_index(symbolic_container(indp), sym)
 Check whether the given `sym` is a timeseries parameter in `indp`.
 """
 function is_timeseries_parameter(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
-        is_timeseries_parameter(symbolic_container(indp), sym)
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) &&
+       (sc = symbolic_container(indp)) != indp
+        is_timeseries_parameter(sc, sym)
     else
         return false
     end
@@ -91,7 +97,8 @@ parameter in `indp`. Defaults to returning `nothing`. Respects the
 [`symbolic_container`](@ref) fallback for `indp` if present.
 """
 function timeseries_parameter_index(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) &&
+       (sc = symbolic_container(indp)) != indp
         timeseries_parameter_index(symbolic_container(indp), sym)
     else
         return nothing
@@ -111,7 +118,8 @@ By default, this function returns `nothing`, indicating that the index provider
 support generating parameter observed functions.
 """
 function parameter_observed(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) &&
+       (sc = symbolic_container(indp)) != indp
         return parameter_observed(symbolic_container(indp), sym)
     else
         return nothing
@@ -143,7 +151,8 @@ variable.
 By default, this function returns `Set([ContinuousTimeseries()])`.
 """
 function get_all_timeseries_indexes(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) &&
+       (sc = symbolic_container(indp)) != indp
         return get_all_timeseries_indexes(symbolic_container(indp), sym)
     else
         return Set([ContinuousTimeseries()])
@@ -240,7 +249,8 @@ Return a dictionary mapping symbols in the index provider to their default value
 This includes parameter symbols. The dictionary must be mutable.
 """
 function default_values(indp)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) &&
+       (sc = symbolic_container(indp)) != indp
         default_values(symbolic_container(indp))
     else
         Dict()