Add queries to check is a name is reserved

Prior to this change, code which was checking whether a name was
reserved in a given scope would need to fetch the relevant set of names
and check whether the name was in it directly.

This change adds query functions which allow the checks to be performed
directly. The query functions recurse to the parent scope, rather than
needing to fetch a new set containing this scope's names and the parent
scope's.

Author: leamingrad

src/fluent_compiler/codegen.py

@@ -122,15 +122,36 @@ def names_in_use(self):
             names = names | self.parent_scope.names_in_use()
         return names
 
+    def is_name_in_use(self, name: str) -> bool:
+        if name in self.names:
+            return True
+
+        if self.parent_scope is None:
+            return False
+
+        return self.parent_scope.is_name_in_use(name)
+
     def function_arg_reserved_names(self):
         names = self._function_arg_reserved_names
         if self.parent_scope is not None:
             names = names | self.parent_scope.function_arg_reserved_names()
         return names
 
+    def is_name_reserved_function_arg(self, name: str) -> bool:
+        if name in self._function_arg_reserved_names:
+            return True
+
+        if self.parent_scope is None:
+            return False
+
+        return self.parent_scope.is_name_reserved_function_arg(name)
+
     def all_reserved_names(self):
         return self.names_in_use() | self.function_arg_reserved_names()
 
+    def is_name_reserved(self, name: str) -> bool:
+        return self.is_name_in_use(name) or self.is_name_reserved_function_arg(name)
+
     def reserve_name(self, requested, function_arg=False, is_builtin=False, properties=None):
         """
         Reserve a name as being in use in a scope.