bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Document the order of {Vec,VecDeque,String}::retain

Browse source 
It's natural for `retain` to work in order from beginning to end, but
this wasn't actually documented to be the case. If we actually promise
this, then the caller can do useful things like track the index of each
element being tested, as [discussed in the forum][1]. This is now
documented for `Vec`, `VecDeque`, and `String`.

[1]: https://users.rust-lang.org/t/vec-retain-by-index/27697

`HashMap` and `HashSet` also have `retain`, and the `hashbrown`
implementation does happen to use a plain `iter()` order too, but it's
not certain that this should always be the case for these types.
This commit is contained in:
Josh Stone 2019-04-29 18:32:05 -07:00
parent 00859e3e65
commit 9b3583375d
3 changed files with 6 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

4
src/liballoc/vec.rs
View file

@ -937,8 +937,8 @@ impl<T> Vec<T> {
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all elements `e` such that `f(&e)` returns `false`.
/// This method operates in place and preserves the order of the retained
/// elements.
/// This method operates in place, visiting each element exactly once in the
/// original order, and preserves the order of the retained elements.
///
/// # Examples
///