Explicit resolved ASTs

src/ytdl_sub/config/overrides.py

@@ -158,10 +158,15 @@ class Overrides(UnstructuredDictFormatterValidator, Scriptable):
             script = entry.script
             unresolvable = entry.unresolvable
 
+        # Update the script internally so long as we are not supplying overrides
+        # that could alter the script with one-off state
+        update = function_overrides is None
+
         try:
             return script.resolve_once(
                 dict({"tmp_var": formatter.format_string}, **(function_overrides or {})),
                 unresolvable=unresolvable,
+                update=update,
             )["tmp_var"]
         except ScriptVariableNotResolved as exc:
             raise StringFormattingException(

src/ytdl_sub/script/script.py

@@ -10,6 +10,7 @@ from ytdl_sub.script.script_output import ScriptOutput
 from ytdl_sub.script.types.resolvable import BuiltInFunctionType
 from ytdl_sub.script.types.resolvable import Lambda
 from ytdl_sub.script.types.resolvable import Resolvable
+from ytdl_sub.script.types.syntax_tree import ResolvedSyntaxTree
 from ytdl_sub.script.types.syntax_tree import SyntaxTree
 from ytdl_sub.script.types.variable import FunctionArgument
 from ytdl_sub.script.types.variable import Variable
@@ -273,7 +274,7 @@ class Script:
 
     def _update_internally(self, resolved_variables: Dict[str, Resolvable]) -> None:
         for variable_name, resolved in resolved_variables.items():
-            self._variables[variable_name] = SyntaxTree(ast=[resolved])
+            self._variables[variable_name] = ResolvedSyntaxTree(ast=[resolved])
 
     def _recursive_get_unresolved_output_filter_variables(
         self, current_var: SyntaxTree, subset_to_resolve: Set[str], unresolvable: Set[Variable]
@@ -522,6 +523,7 @@ class Script:
         variable_definitions: Dict[str, str],
         resolved: Optional[Dict[str, Resolvable]] = None,
         unresolvable: Optional[Set[str]] = None,
+        update: bool = False,
     ) -> Dict[str, Resolvable]:
         """
         Given a new set of variable definitions, resolve them using the Script, but do not
@@ -536,6 +538,8 @@ class Script:
         unresolvable
             Optional. Unresolvable variables that will be ignored in resolution, including all
             variables with a dependency to them.
+        update
+            Whether to update the script's state with resolved variables. Defaults to False.
 
         Returns
         -------
@@ -548,6 +552,7 @@ class Script:
                 pre_resolved=resolved,
                 unresolvable=unresolvable,
                 output_filter=set(list(variable_definitions.keys())),
+                update=update,
             ).output
         finally:
             for name in variable_definitions.keys():

src/ytdl_sub/script/types/syntax_tree.py

@@ -50,3 +50,17 @@ class SyntaxTree(VariableDependency):
         if len(self.ast) == 1 and isinstance(self.ast[0], Resolvable):
             return self.ast[0]
         return None
+
+
+@dataclass(frozen=True)
+class ResolvedSyntaxTree(SyntaxTree):
+    def resolve(
+        self,
+        resolved_variables: Dict[Variable, Resolvable],
+        custom_functions: Dict[str, VariableDependency],
+    ) -> Resolvable:
+        return self.ast[0]
+
+    @property
+    def maybe_resolvable(self) -> Optional[Resolvable]:
+        return self.ast[0]

src/ytdl_sub/validators/string_formatter_validators.py

@@ -246,6 +246,7 @@ def _validate_formatter(
                 )
             },
             unresolvable=unresolvable,
+            update=True,
         )
     except RuntimeException as exc:
         if isinstance(exc, ScriptVariableNotResolved) and is_static_formatter: