as_ptr returns a read-only pointer
Add comments to `as_ptr` methods to warn that these are read-only pointers, and writing to them is UB.
[It was pointed out](https://internals.rust-lang.org/t/as-ptr-vs-as-mut-ptr/9940) that `CStr` does not even have an `as_mut_ptr`. I originally was going to add one, but there is no method at all that would mutate a `CStr`. Was that a deliberate choice or should I add an `as_mut_ptr` (similar to [what I did for `str`](https://github.com/rust-lang/rust/pull/58200))?
Add implementations of last in terms of next_back on a bunch of DoubleEndedIterators
Provided a `DoubleEndedIterator` has finite length, `Iterator::last` is equivalent to `DoubleEndedIterator::next_back`. But searching forwards through the iterator when it's unnecessary is obviously not good for performance. I ran into this on one of the collection iterators.
I tried adding appropriate overloads for a bunch of the iterator adapters like filter, map, etc, but I ran into a lot of type inference failures after doing so.
The other interesting case is what to do with `Repeat`. Do we consider it part of the contract that `Iterator::last` will loop forever on it? The docs do say that the iterator will be evaluated until it returns None. This is also relevant for the adapters, it's trivially easy to observe whether a `Map` adapter invoked its closure a zillion times or just once for the last element.
Fix small errors in docs for `rchunks_exact` and `rchunks_exact_mut`.
The documentation for `rchunks_exact` said it started at the beginning
of the slice, bit it actually starts at the end of the slice.
In addition, there were a couple of "of the slice of the slice"
duplicate phrases going on for `rchunks_exact` and `rchunks_exact_mut`.
This fixes#60068.
The documentation for `rchunks_exact` said it started at the beginning
of the slice, bit it actually starts at the end of the slice.
In addition, there were a couple of "of the slice of the slice"
duplicate phrases going on for `rchunks_exact` and `rchunks_exact_mut`.
This fixes#60068.
Implement specialized nth_back() for Box and Windows.
Hi there, this is my first pull request to rust :-)
I started implementing some specializations for DoubleEndedIterator::nth_back() and these are the first two. The problem has been discussed in #54054 and nth_back() is tracked in #56995.
I'm stuck with the next implementation so I though I do a PR for the ones I'm confident with to get some feedback.
Add some more notes to the documentation:
- Mention that the median can be found if we used `len() / 2`.
- Mention that this function is usually called "kth element" in other libraries.
Address some comments in PR:
- Change wording on some of the documentation
- Change recursive function into a loop
Update name to `partition_at_index` and add convenience return values.
Address reviewer comments:
- Don't swap on each iteration when searching for min/max element.
- Add some docs about when we panic.
- Test that the sum of the lengths of the output matches the length of the input.
- Style fix for for-loop.
Address more reviewer comments
Fix Rng stuff for test
Fix doc test build
Don't run the partition_at_index test on wasm targets
Miri does not support entropy for test partition_at_index
In bluss/indexmap#88, we found that there was no easy way to implement
`Debug` for our `IterMut` and `Drain` iterators. Those are built on
`slice::IterMut` and `vec::Drain`, which implement `Debug` themselves,
but have no other way to access their data. With a new `as_slice()`
method, we can read the data and customize its presentation.
There are two big categories of changes in here
- Removing lifetimes from common traits that can essentially never user a lifetime from an input (particularly `Drop` & `Debug`)
- Forwarding impls that are only possible because the lifetime doesn't matter (like `impl<R: Read + ?Sized> Read for &mut R`)
I omitted things that seemed like they could be more controversial, like the handful of iterators that have a `Item: 'static` despite the iterator having a lifetime or the `PartialEq` implementations where the flipped one cannot elide the lifetime.
Additionally, the root implementation was changed a bit: it now uses
`all` instead of coding that logic manually.
To avoid duplicate code, the inherent `[T]::is_sorted_by` method now
calls `self.iter().is_sorted_by(...)`. This should always be inlined
and not result in overhead.
Doc total order requirement of sort(_unstable)_by
I took the definition of what a total order is from the Ord trait
docs. I specifically put "elements of the slice" because if you
have a slice of f64s, but know none are NaN, then sorting by
partial ord is total in this case. I'm not sure if I should give
such an example in the docs or not.
r? @GuillaumeGomez
