Skip to content

Optimize MapSet.symmetric_difference/2 when sizes mismatched #15471

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
josevalim merged 3 commits into from
Jun 14, 2026
Merged

Optimize MapSet.symmetric_difference/2 when sizes mismatched #15471

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
a09720d
Optimize MapSet.symmetric_difference/2 when sizes mismatched
preciz Jun 13, 2026
68a89c9
Further optimize MapSet.symmetric_difference
preciz Jun 14, 2026
17c2c9c
No comparison required
preciz Jun 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 5 additions & 9 deletions lib/elixir/lib/map_set.ex
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -171,18 +171,14 @@ defmodule MapSet do
@doc since: "1.14.0"
@spec symmetric_difference(t(val1), t(val2)) :: t(val1 | val2) when val1: value, val2: value
def symmetric_difference(%MapSet{map: set1} = map_set1, %MapSet{map: set2} = _map_set2) do
{small, large} = if :sets.size(set1) <= :sets.size(set2), do: {set1, set2}, else: {set2, set1}

disjointer_fun = fn elem, {small, acc} ->
if :sets.is_element(elem, small) do
{:sets.del_element(elem, small), acc}
map =
if :sets.is_disjoint(set1, set2) do
:sets.union(set1, set2)
else
{small, [elem | acc]}
:sets.union(:sets.subtract(set1, set2), :sets.subtract(set2, set1))
end
end

{new_small, list} = :sets.fold(disjointer_fun, {small, []}, large)
%{map_set1 | map: :sets.union(new_small, :sets.from_list(list, version: 2))}
%{map_set1 | map: map}
end

@doc """
Expand Down
Loading