diff --git a/synapse/util/iterutils.py b/synapse/util/iterutils.py
index 4938ddf703..a0efb96d3b 100644
--- a/synapse/util/iterutils.py
+++ b/synapse/util/iterutils.py
@@ -15,11 +15,13 @@
import heapq
from itertools import islice
from typing import (
+ Callable,
Collection,
Dict,
Generator,
Iterable,
Iterator,
+ List,
Mapping,
Set,
Sized,
@@ -71,6 +73,31 @@ def chunk_seq(iseq: S, maxlen: int) -> Iterator[S]:
return (iseq[i : i + maxlen] for i in range(0, len(iseq), maxlen))
+def partition(
+ iterable: Iterable[T], predicate: Callable[[T], bool]
+) -> Tuple[List[T], List[T]]:
+ """
+ Separate a given iterable into two lists based on the result of a predicate function.
+
+ Args:
+ iterable: the iterable to partition (separate)
+ predicate: a function that takes an item from the iterable and returns a boolean
+
+ Returns:
+ A tuple of two lists, the first containing all items for which the predicate
+ returned True, the second containing all items for which the predicate returned
+ False
+ """
+ true_results = []
+ false_results = []
+ for item in iterable:
+ if predicate(item):
+ true_results.append(item)
+ else:
+ false_results.append(item)
+ return true_results, false_results
+
+
def sorted_topologically(
nodes: Iterable[T],
graph: Mapping[T, Collection[T]],
|
