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Comment why get_or_insert returns &T

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This commit is contained in:
Josh Stone 2019-05-16 16:21:31 -07:00
parent 5e2c9d38e9
commit 9161a4dbef
1 changed files with 4 additions and 0 deletions
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4
src/libstd/collections/hash/set.rs
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@ -637,6 +637,8 @@ impl<T, S> HashSet<T, S>
#[inline]
#[unstable(feature = "hash_set_entry", issue = "60896")]
pub fn get_or_insert(&mut self, value: T) -> &T {
// Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
// `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
self.map.raw_entry_mut().from_key(&value).or_insert(value, ()).0
}
@ -667,6 +669,8 @@ impl<T, S> HashSet<T, S>
Q: Hash + Eq,
F: FnOnce(&Q) -> T
{
// Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
// `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
self.map.raw_entry_mut().from_key(value).or_insert_with(|| (f(value), ())).0
}