Support reverse iteration of DataStore (#113)

pybotters · Jan 5, 2022 · 064fa92 · 064fa92
1 parent 2eb1117
commit 064fa92
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diff --git a/pybotters/store.py b/pybotters/store.py
@@ -36,6 +36,9 @@ def __len__(self) -> int:
     def __iter__(self) -> Iterator[Item]:
         return iter(self._data.values())
 
+    def __reversed__(self) -> Iterator[Item]:
+        return reversed(self._data.values())
+
     @staticmethod
     def _hash(item: dict[str, Hashable]) -> int:
         return hash(tuple(item.items()))

diff --git a/tests/test_store.py b/tests/test_store.py
@@ -1,4 +1,5 @@
 import asyncio
+import sys
 import uuid
 
 import pytest
@@ -285,6 +286,23 @@ def test__iter__():
         next(data_iter)
 
 
+def test__reversed__():
+    data = [{'foo': f'bar{i}'} for i in range(5)]
+    ds = pybotters.store.DataStore(keys=['foo'], data=data)
+    if sys.version_info.major == 3 and sys.version_info.minor >= 8:
+        data_iter = reversed(ds)
+        assert next(data_iter) == {'foo': 'bar4'}
+        assert next(data_iter) == {'foo': 'bar3'}
+        assert next(data_iter) == {'foo': 'bar2'}
+        assert next(data_iter) == {'foo': 'bar1'}
+        assert next(data_iter) == {'foo': 'bar0'}
+        with pytest.raises(StopIteration):
+            next(data_iter)
+    else:
+        with pytest.raises(TypeError):
+            data_iter = reversed(ds)
+
+
 def test_set():
     ds = pybotters.store.DataStore()
     event = asyncio.Event()