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Auto merge of #79895 - Kerollmops:slice-group-by, r=m-ou-se

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The return of the GroupBy and GroupByMut iterators on slice

According to https://github.com/rust-lang/rfcs/pull/2477#issuecomment-742034372, I am opening this PR again, this time I implemented it in safe Rust only, it is therefore much easier to read and is completely safe.

This PR proposes to add two new methods to the slice, the `group_by` and `group_by_mut`. These two methods provide a way to iterate over non-overlapping sub-slices of a base slice that are separated by the predicate given by the user (e.g. `Partial::eq`, `|a, b| a.abs() < b.abs()`).

```rust
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];

let mut iter = slice.group_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
```

[An RFC](https://github.com/rust-lang/rfcs/pull/2477) was open 2 years ago but wasn't necessary.
This commit is contained in:
bors 2020-12-31 12:00:43 +00:00
commit b33e234155
7 changed files with 330 additions and 0 deletions
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1
library/alloc/src/lib.rs
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@ -139,6 +139,7 @@
#![feature(try_trait)]
#![feature(type_alias_impl_trait)]
#![feature(associated_type_bounds)]
#![feature(slice_group_by)]
// Allow testing this library
#[cfg(test)]

2
library/alloc/src/slice.rs
View file

@ -110,6 +110,8 @@ pub use core::slice::{Chunks, Windows};
pub use core::slice::{ChunksExact, ChunksExactMut};
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::slice::{ChunksMut, Split, SplitMut};
#[unstable(feature = "slice_group_by", issue = "80552")]
pub use core::slice::{GroupBy, GroupByMut};
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::slice::{Iter, IterMut};
#[stable(feature = "rchunks", since = "1.31.0")]