fix: Fix some edge cases of initial state configuration

Author: fgmacedo

statemachine/engines/base.py

@@ -602,10 +602,7 @@ def add_descendant_states_to_enter(
                     )
         elif state and state.is_compound:
             states_for_default_entry.add(info)
-            initial_state = next(s for s in state.states if s.initial)
-            transition = next(
-                t for t in state.transitions if t.initial and t.target == initial_state
-            )
+            transition = next(t for t in state.transitions if t.initial)
             info_initial = StateTransition(
                 transition=transition,
                 target=transition.target,

statemachine/factory.py

@@ -95,7 +95,8 @@ def _initials_by_document_order(
         for s in states:
             s.document_order = order
             order += 1
-            cls._initials_by_document_order(s.states, s, order)
+            if s.states:
+                cls._initials_by_document_order(s.states, s, order)
             if s.initial:
                 initial = s
         if not initial and states:

statemachine/io/scxml/actions.py

@@ -27,7 +27,7 @@
 from .schema import ScriptAction
 
 logger = logging.getLogger(__name__)
-protected_attrs = _event_data_kwargs | {"_sessionid", "_ioprocessors", "_name"}
+protected_attrs = _event_data_kwargs | {"_sessionid", "_ioprocessors", "_name", "_event"}
 
 
 class ParseTime:

statemachine/io/scxml/parser.py

@@ -1,5 +1,6 @@
 import re
 import xml.etree.ElementTree as ET
+from typing import Iterable
 from typing import Set
 
 from .schema import Action
@@ -33,13 +34,20 @@ def strip_namespaces(tree: ET.Element):
                 attrib[new_name] = attrib.pop(name)
 
 
+def visit_states(states: Iterable[State], parents: list[State]):
+    for state in states:
+        yield state, parents
+        if state.states:
+            yield from visit_states(state.states.values(), parents + [state])
+
+
 def _parse_initial(initial_content: "str | None") -> Set[str]:
     if initial_content is None:
         return set()
     return set(initial_content.split())
 
 
-def parse_scxml(scxml_content: str) -> StateMachineDefinition:
+def parse_scxml(scxml_content: str) -> StateMachineDefinition:  # noqa: C901
     root = ET.fromstring(scxml_content)
     strip_namespaces(root)
 
@@ -75,6 +83,21 @@ def parse_scxml(scxml_content: str) -> StateMachineDefinition:
         for s in definition.initial_states:
             definition.states[s].initial = True
 
+    # If the initial states definition does not contain any first level state,
+    # we find the first level states that are ancestor of the initial states
+    # and also set them as the initial states.
+    if not set(definition.states.keys()) & definition.initial_states:
+        not_found = set(definition.initial_states)
+        for state, parents in visit_states(definition.states.values(), []):
+            if state.id in definition.initial_states:
+                not_found.remove(state.id)
+                if parents:
+                    topmost_state = parents[0]
+                    topmost_state.initial = True
+                    definition.initial_states.add(topmost_state.id)
+            if not not_found:
+                break
+
     return definition
 
 

statemachine/io/scxml/processor.py

@@ -65,12 +65,16 @@ def process_definition(self, definition, location: str):
         if definition.datamodel:
             datamodel = create_datamodel_action_callable(definition.datamodel)
             if datamodel:
-                initial_state = next(s for s in iter(states_dict.values()) if s["initial"])
+                try:
+                    initial_state = next(s for s in iter(states_dict.values()) if s.get("initial"))
+                except StopIteration:
+                    # If there's no explicit initial state, use the first one
+                    initial_state = next(iter(states_dict.values()))
+
                 if "enter" not in initial_state:
                     initial_state["enter"] = []
                 if isinstance(initial_state["enter"], list):
                     initial_state["enter"].insert(0, datamodel)
-
         self._add(location, {"states": states_dict, "prepare_event": self._prepare_event})
 
     def _prepare_event(self, *args, **kwargs):

tests/scxml/w3c/mandatory/test346.fail.md

@@ -6,6 +6,7 @@ we enter s0 first we succeed, if s1, failure. -->
 
   <state id="s0">
     <transition target="pass" />
+    <transition target="s1" cond="1 &lt; 0" /><!-- fgm: added to have a single component in graph -->
   </state>
 
   <state id="s1">