fix: arrangement parse logic (partly), closes #32

Author: anandsshah

pyflp/arrangement.py

@@ -377,7 +377,7 @@ def _collect_events(self, enum_: type[EventEnum]):
                 ins_events.append(events)
 
         ins_dict: DefaultDict[int, list[AnyEvent]] = collections.defaultdict(list)
-        for i in range(max(counter)):
+        for i in range(max(counter, default=0)):
             for sublist in ins_events:
                 try:
                     event = sublist[i]
@@ -441,26 +441,25 @@ def __getitem__(self, index: SupportsIndex) -> Arrangement:
     # parse; it contains ArrangementID.New event followed by TimeMarker events
     # followed by 500 TrackID events. TimeMarkers occured before new arrangement
     # event in initial versions of FL20, making them harder to group.
+    # TODO This logic might not work on older versions of FL.
     def __iter__(self) -> Iterator[Arrangement]:
-        first = True
-        events: list[AnyEvent] = []
-
-        def make_arr():
-            return Arrangement(*events, version=self._kw["version"])
+        """Provides an iterator over :class:`Arrangement`s found in the project.
 
+        Raises:
+            NoModelsFound: When no arrangements are found.
+        """
+        arrs_evs: list[list[AnyEvent]] = [[] for _ in range(len(self))]
+        idx = 0
         for event in self._events_tuple:
             if event.id == ArrangementID.New:
-                if not first:
-                    yield make_arr()
-                    events = []
-                first = not first
-            elif event.id == ArrangementsID.Current:
-                return make_arr()  # last arrangement
+                idx = event.value
 
             for enum_ in (ArrangementID, TimeMarkerID, TrackID):
                 if event.id in enum_:
-                    events.append(event)
-                    break
+                    arrs_evs[idx].append(event)
+
+        for arr_evs in arrs_evs:
+            yield Arrangement(*arr_evs, version=self._kw["version"])
 
     def __len__(self):
         """The number of arrangements present in the project.
@@ -488,8 +487,8 @@ def current(self) -> Arrangement | None:
             index = event.value
             try:
                 return list(self)[index]
-            except IndexError:
-                raise ModelNotFound(index)
+            except IndexError as exc:
+                raise ModelNotFound(index) from exc
 
     height = EventProp[int](ArrangementsID.WindowHeight)
     """Window height / track width used by the interface."""

pyflp/pattern.py

@@ -101,7 +101,8 @@ class PatternsID(EventEnum):
 # ChannelIID, _161, _162, Looped, Length occur when pattern is looped.
 # ChannelIID and _161 occur for every channel in order.
 # ! Looping a pattern puts timemarkers in it. The same TimeMarkerID events are
-# !used, which means I need to refactor it out from pyflp.arrangement.
+# ! used, which means I need to refactor it out from pyflp.arrangement.
+# TODO Patterns share TimeMarker events with Arrangements
 class PatternID(EventEnum):
     Looped = (26, BoolEvent)
     New = (WORD + 1, U16Event)  # Marks the beginning of a new pattern, twice.

pyflp/project.py

@@ -164,22 +164,32 @@ def __init__(self, *events: AnyEvent, **kw: Unpack[_ProjectKW]):
     def __repr__(self) -> str:
         return f"FL Studio {str(self.version)} {self.format.name}"
 
-    def _collect_events(self, *enums: type[EventEnum]) -> list[AnyEvent]:
-        events: list[AnyEvent] = []
+    def _collect_events(self, *enums: type[EventEnum]):
         for event in self._events_tuple:
             for enum_ in enums:
                 if event.id in enum_:
-                    events.append(event)
+                    yield event
                     break
-        return events
 
     @property
     def arrangements(self) -> Arrangements:
         """Provides an iterator over arrangements and other related properties."""
-        return Arrangements(
-            *self._collect_events(ArrangementID, ArrangementsID, TrackID, TimeMarkerID),
-            version=self.version,
-        )
+        arrnew_occured = False
+        filtered_events: list[AnyEvent] = []
+        for event in self._collect_events(
+            ArrangementID, ArrangementsID, TrackID, TimeMarkerID
+        ):
+            if event.id == ArrangementID.New:
+                arrnew_occured = True
+
+            # * Prevents accidentally passing on Pattern's timemarkers
+            # TODO This logic will still be incorrect if arrangement's
+            # timemarkers occur before ArrangementID.New event.
+            elif event.id in TimeMarkerID and not arrnew_occured:
+                continue
+            filtered_events.append(event)
+
+        return Arrangements(*filtered_events, version=self.version)
 
     artists = EventProp[str](ProjectID.Artists)
     """Authors / artists info. to be embedded in exported WAV & MP3.