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Add __reversed__ support to keys, values, and items views #1304

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Add __reversed__ support to keys, values, and items views #1304

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1 change: 1 addition & 0 deletions CHANGES/448.feature.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Added support for reversing keys, values, and items views via ``reversed()`` -- implements :issue:`448`.
30 changes: 30 additions & 0 deletions multidict/_multidict_py.py
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Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,15 @@ def _iter(self, version: int) -> Iterator[tuple[str, _V]]:
raise RuntimeError("Dictionary changed during iteration")
yield self._md._key(e.key), e.value

def __reversed__(self) -> Iterator[tuple[str, _V]]:
return _Iter(len(self), self._iter_reversed(self._md._version))

def _iter_reversed(self, version: int) -> Iterator[tuple[str, _V]]:
for e in self._md._keys.iter_entries_reverse():
if version != self._md._version:
raise RuntimeError("Dictionary changed during iteration")
yield self._md._key(e.key), e.value

@reprlib.recursive_repr()
def __repr__(self) -> str:
lst = []
Expand Down Expand Up @@ -272,6 +281,15 @@ def _iter(self, version: int) -> Iterator[_V]:
raise RuntimeError("Dictionary changed during iteration")
yield e.value

def __reversed__(self) -> Iterator[_V]:
return _Iter(len(self), self._iter_reversed(self._md._version))

def _iter_reversed(self, version: int) -> Iterator[_V]:
for e in self._md._keys.iter_entries_reverse():
if version != self._md._version:
raise RuntimeError("Dictionary changed during iteration")
yield e.value

@reprlib.recursive_repr()
def __repr__(self) -> str:
lst = []
Expand Down Expand Up @@ -301,6 +319,15 @@ def _iter(self, version: int) -> Iterator[str]:
raise RuntimeError("Dictionary changed during iteration")
yield self._md._key(e.key)

def __reversed__(self) -> Iterator[str]:
return _Iter(len(self), self._iter_reversed(self._md._version))

def _iter_reversed(self, version: int) -> Iterator[str]:
for e in self._md._keys.iter_entries_reverse():
if version != self._md._version:
raise RuntimeError("Dictionary changed during iteration")
yield self._md._key(e.key)

def __repr__(self) -> str:
lst = []
for e in self._md._keys.iter_entries():
Expand Down Expand Up @@ -595,6 +622,9 @@ def del_idx(self, hash_: int, idx: int) -> None:
def iter_entries(self) -> Iterator[_Entry[_V]]:
return filter(None, self.entries)

def iter_entries_reverse(self) -> Iterator[_Entry[_V]]:
return filter(None, reversed(self.entries))

def restore_hash(self, hash_: int) -> None:
mask = self.mask
indices = self.indices
Expand Down
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