Merge pull request ricklupton#36 from ricklupton/fix-crdt-sequence

Ignore unknown IDs in sorting CrdtSequence

README.md

@@ -10,6 +10,9 @@ To convert rm files to other formats, you can use [rmc](https://github.com/rickl
 
 ### Unreleased
 
+Fixes:
+- Fix AssertionError when some ids are missing in a `CrdtSequence` ([#36](https://github.com/ricklupton/rmscene/pull/36))
+
 ### v0.6.0
 
 New features:

src/rmscene/crdt_sequence.py

@@ -2,13 +2,16 @@
 
 """
 
+import logging
 import typing as tp
 from typing import Iterable
 from collections import defaultdict
 from dataclasses import dataclass
 
 from .tagged_block_common import CrdtId
 
+_logger = logging.getLogger(__name__)
+
 
 # If the type constraint is for a CrdtSequenceItem[Superclass], then a
 # CrdtSequenceItem[Subclass] would do, so it is covariant.
@@ -108,7 +111,9 @@ def toposort_items(items: Iterable[CrdtSequenceItem]) -> Iterable[CrdtId]:
 
     def _side_id(item, side):
         side_id = getattr(item, f"{side}_id")
-        if side_id == END_MARKER:
+        if side_id == END_MARKER or side_id not in item_dict:
+            if side_id != END_MARKER:
+                _logger.debug("Ignoring unknown %s_id %s of %s", side, side_id, item)
             return "__start" if side == "left" else "__end"
         else:
             return side_id

tests/test_crdt_sequence.py

@@ -71,6 +71,17 @@ def test_unknown_id():
     assert result1 == [cid(28), cid(31), cid(33), cid(15)]
 
 
+def test_unknown_id_at_right():
+    items = [
+        make_item(14, 0, 0, 0, "A"),
+        make_item(19, 14, 15, 0, "V"),
+        # item 15 is not defined -- this shouldn't happen, as there should be a
+        # tombstone, but don't want to raise errors in this case
+    ]
+    result = list(CrdtSequence(items))
+    assert result == [cid(14), cid(19)]
+
+
 def test_iterates_in_order():
     # Order should be "AB"
     items = [