| Age | Commit message (Collapse) | Author | Lines |
|---|
|
Simplify 'product' factorial example
This simplifies the [`factorial(n: 32)`](https://doc.rust-lang.org/std/iter/trait.Iterator.html#examples-46) implementation as example for the `Iterator::product()` function.
It currently uses unnecessary additional complexity.
Although very minimal, I do not want to include it in some other irrelevant PR.
|
|
Add core::iter::once_with()
Functions `iter::once()` and `iter::repeat()` construct iterators from values. The latter has the lazy variant `iter::repeat_with()`, but the former doesn't. This PR therefore adds `iter::once_with()`.
Another way to think of `iter::once_with()` is that it's a function that converts `FnOnce() -> T` into `Iterator<Item = T>`.
If this seems like a reasonable addition, I'll open a tracking issue and update the `#[feature(...)]` attributes.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Add unstable Iterator::copied()
Initially suggested at https://github.com/bluss/rust-itertools/pull/289, however the maintainers of itertools suggested this may be better of in a standard library.
The intent of `copied` is to avoid accidentally cloning iterator elements after doing a code refactoring which causes a structure to be no longer `Copy`. This is a relatively common pattern, as it can be seen by calling `rg --pcre2 '[.]map[(][|](?:(\w+)[|] [*]\1|&(\w+)[|] \2)[)]'` on Rust main repository. Additionally, many uses of `cloned` actually want to simply `Copy`, and changing something to be no longer copyable may introduce unnoticeable performance penalty.
Also, this makes sense because the standard library includes `[T].copy_from_slice` to pair with `[T].clone_from_slice`.
This also adds `Option::copied`, because it makes sense to pair it with `Iterator::copied`. I don't think this feature is particularly important, but it makes sense to update `Option` along with `Iterator` for consistency.
|
|
|
|
|
|
Add missing link in docs
r? @steveklabnik
|
|
|
|
|
|
Fix grammar in compiler error for array iterators
This fixes a small grammatical mistake in the message the compiler gives when attempting to iterate directly over an array `arr` without calling `arr.iter()` or borrowing `&arr`.
|
|
Remove Cycle::try_fold override
Fixes #56883
|
|
It was a incorrect optimization.
|
|
|
|
|
|
Resolve FIXME in libcore/iter/mod.rs
and makes a few improvements.
|
|
|
|
|
|
name old ns/iter new ns/iter diff ns/iter diff % speedup
iter::bench_cycle_take_ref_sum 927,152 927,194 42 0.00% x 1.00
iter::bench_cycle_take_sum 938,129 603,492 -334,637 -35.67% x 1.55
|
|
|
|
|
|
Previous implementation wasn't correct, as an inner iterator
could have had side effects.
|
|
|
|
|
|
|
|
|
|
|
|
Add std::iter::unfold
This adds an **unstable** ~`std::iter::iterate`~ `std::iter::unfold` function and ~`std::iter::Iterate`~ `std::iter::Unfold` type that trivially wrap a ~`FnMut() -> Option<T>`~ `FnMut(&mut State) -> Option<T>` closure to create an iterator. ~Iterator state can be kept in the closure’s environment or captures.~
This is intended to help reduce amount of boilerplate needed when defining an iterator that is only created in one place. Compare the existing example of the `std::iter` module: (explanatory comments elided)
```rust
struct Counter {
count: usize,
}
impl Counter {
fn new() -> Counter {
Counter { count: 0 }
}
}
impl Iterator for Counter {
type Item = usize;
fn next(&mut self) -> Option<usize> {
self.count += 1;
if self.count < 6 {
Some(self.count)
} else {
None
}
}
}
```
… with the same algorithm rewritten to use this new API:
```rust
fn counter() -> impl Iterator<Item=usize> {
std::iter::unfold(0, |count| {
*count += 1;
if *count < 6 {
Some(*count)
} else {
None
}
})
}
```
-----
This also add unstable `std::iter::successors` which takes an (optional) initial item and a closure that takes an item and computes the next one (its successor).
```rust
let powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
assert_eq!(powers_of_10.collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);
```
|
|
Fix #[cfg] for step impl on ranges
```#[cfg(target_pointer_witdth = ...)]``` is misspelled
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Document optimizations enabled by FusedIterator
When reading this I wondered what “some significant optimizations” referred to. As far as I can tell from reading code, the specialization of `.fuse()` is the only case where `FusedIterator` has any impact at all. Is this accurate @Stebalien?
|
|
When reading this I wondered what “some significant optimizations” referred to. As far as I can tell, the specialization of `.fuse()` is the only case where `FusedIterator` has any impact at all. Is this accurate @Stebalien?
|
|
|
|
|
|
|
|
to #49098
|
|
Add filtering option to `rustc_on_unimplemented` and reword `Iterator` E0277 errors
- Add more targetting filters for arrays to `rustc_on_unimplemented` (Fix #53766)
- Detect one element array of `Range` type, which is potentially a typo:
`for _ in [0..10] {}` where iterating between `0` and `10` was intended.
(Fix #23141)
- Suggest `.bytes()` and `.chars()` for `String`.
- Suggest borrowing or `.iter()` on arrays (Fix #36391)
- Suggest using range literal when iterating on integers (Fix #34353)
- Do not suggest `.iter()` by default (Fix #50773, fix #46806)
- Add regression test (Fix #22872)
|
