Add missing methods to OrderedSet.

Implemented missing method ``copy`` and ``pop`` in OrderedSet class.

Fixes: #9487
Change-Id: I1d2278b64939b44422e9d5857ec7d345fff53997

1 files changed, 28 insertions, 9 deletions

diff --git a/lib/sqlalchemy/util/_py_collections.py b/lib/sqlalchemy/util/_py_collections.py
index 8810800c4..9962493b5 100644
--- a/lib/sqlalchemy/util/_py_collections.py
+++ b/lib/sqlalchemy/util/_py_collections.py
@@ -168,8 +168,11 @@ class OrderedSet(Set[_T]):
         else:
             self._list = []
 
-    def __reduce__(self):
-        return (OrderedSet, (self._list,))
+    def copy(self) -> OrderedSet[_T]:
+        cp = self.__class__()
+        cp._list = self._list.copy()
+        set.update(cp, cp._list)
+        return cp
 
     def add(self, element: _T) -> None:
         if element not in self:
@@ -180,6 +183,14 @@ class OrderedSet(Set[_T]):
         super().remove(element)
         self._list.remove(element)
 
+    def pop(self) -> _T:
+        try:
+            value = self._list.pop()
+        except IndexError:
+            raise KeyError("pop from an empty set") from None
+        super().remove(value)
+        return value
+
     def insert(self, pos: int, element: _T) -> None:
         if element not in self:
             self._list.insert(pos, element)
@@ -220,9 +231,8 @@ class OrderedSet(Set[_T]):
         return self  # type: ignore
 
     def union(self, *other: Iterable[_S]) -> OrderedSet[Union[_T, _S]]:
-        result: OrderedSet[Union[_T, _S]] = self.__class__(self)  # type: ignore  # noqa: E501
-        for o in other:
-            result.update(o)
+        result: OrderedSet[Union[_T, _S]] = self.copy()  # type: ignore
+        result.update(*other)
         return result
 
     def __or__(self, other: AbstractSet[_S]) -> OrderedSet[Union[_T, _S]]:
@@ -237,9 +247,17 @@ class OrderedSet(Set[_T]):
         return self.intersection(other)
 
     def symmetric_difference(self, other: Iterable[_T]) -> OrderedSet[_T]:
-        other_set = other if isinstance(other, set) else set(other)
+        collection: Collection[_T]
+        if isinstance(other, set):
+            collection = other_set = other
+        elif isinstance(other, Collection):
+            collection = other
+            other_set = set(other)
+        else:
+            collection = list(other)
+            other_set = set(collection)
         result = self.__class__(a for a in self if a not in other_set)
-        result.update(a for a in other if a not in self)
+        result.update(a for a in collection if a not in self)
         return result
 
     def __xor__(self, other: AbstractSet[_S]) -> OrderedSet[Union[_T, _S]]:
@@ -263,9 +281,10 @@ class OrderedSet(Set[_T]):
         return self
 
     def symmetric_difference_update(self, other: Iterable[Any]) -> None:
-        super().symmetric_difference_update(other)
+        collection = other if isinstance(other, Collection) else list(other)
+        super().symmetric_difference_update(collection)
         self._list = [a for a in self._list if a in self]
-        self._list += [a for a in other if a in self]
+        self._list += [a for a in collection if a in self]
 
     def __ixor__(self, other: AbstractSet[_S]) -> OrderedSet[Union[_T, _S]]:
         self.symmetric_difference_update(other)