Motivation: the `selectors` crate is generic over a string type,
in order to support all of `String`, `string_cache::Atom`, and
`gecko_string_cache::Atom`. Multiple trait bounds are used
for the various operations done with these strings.
One of these operations is creating a string (as efficiently as possible,
re-using an existing memory allocation if possible) from `Cow<str>`.
The `std::convert::From` trait seems natural for this, but
the relevant implementation was missing before this PR.
To work around this I’ve added a `FromCowStr` trait in `selectors`,
but with trait coherence that means one of `selectors` or `string_cache`
needs to depend on the other to implement this trait.
Using a trait from `std` would solve this.
The `Vec<T>` implementation is just added for consistency.
I also tried a more general
`impl<'a, O, B: ?Sized + ToOwned<Owned=O>> From<Cow<'a, B>> for O`,
but (the compiler thinks?) it conflicts with `From<T> for T` the impl
(after moving all of `collections::borrow` into `core::borrow`
to work around trait coherence).
Add method str::repeat(self, usize) -> String
It is relatively simple to repeat a string n times:
`(0..n).map(|_| s).collect::<String>()`. It becomes slightly more
complicated to do it “right” (sizing the allocation up front), which
warrants a method that does it for us.
This method is useful in writing testcases, or when generating text.
`format!()` can be used to repeat single characters, but not repeating
strings like this.
It is relatively simple to repeat a string n times:
`(0..n).map(|_| s).collect::<String>()`. It becomes slightly more
complicated to do it “right” (sizing the allocation up front), which
warrants a method that does it for us.
This method is useful in writing testcases, or when generating text.
`format!()` can be used to repeat single characters, but not repeating
strings like this.
std: Stabilize and deprecate APIs for 1.13
This commit is intended to be backported to the 1.13 branch, and works with the
following APIs:
Stabilized
* `i32::checked_abs`
* `i32::wrapping_abs`
* `i32::overflowing_abs`
* `RefCell::try_borrow`
* `RefCell::try_borrow_mut`
Deprecated
* `BinaryHeap::push_pop`
* `BinaryHeap::replace`
* `SipHash13`
* `SipHash24`
* `SipHasher` - use `DefaultHasher` instead in the `std::collections::hash_map`
module
Closes#28147Closes#34767Closes#35057Closes#35070
This commit is intended to be backported to the 1.13 branch, and works with the
following APIs:
Stabilized
* `i32::checked_abs`
* `i32::wrapping_abs`
* `i32::overflowing_abs`
* `RefCell::try_borrow`
* `RefCell::try_borrow_mut`
* `DefaultHasher`
* `DefaultHasher::new`
* `DefaultHasher::default`
Deprecated
* `BinaryHeap::push_pop`
* `BinaryHeap::replace`
* `SipHash13`
* `SipHash24`
* `SipHasher` - use `DefaultHasher` instead in the `std::collections::hash_map`
module
Closes#28147Closes#34767Closes#35057Closes#35070
This does not actually add anything that wasn't there, but is merely an
optimization for the given cases, which would have incurred additional
heap allocation for adding empty strings, and improving the ergonomics
of `Cow` with strings.
Implement `AsRef<[T]>` for `std::slice::Iter`.
`AsRef` is designed for conversions that are "cheap" (as per
the API docs). It is the case that retrieving the underlying
data of `std::slice::Iter` is cheap. In my opinion, there's no
ambiguity about what slice data will be returned, otherwise,
I would be more cautious about implementing `AsRef`.
`AsRef` is designed for conversions that are "cheap" (as per
the API docs). It is the case that retrieving the underlying
data of `std::slice::Iter` is cheap. In my opinion, there's no
ambiguity about what slice data will be returned, otherwise,
I would be more cautious about implementing `AsRef`.
Escape fewer Unicode codepoints in `Debug` impl of `str`
Use the same procedure as Python to determine whether a character is
printable, described in [PEP 3138]. In particular, this means that the
following character classes are escaped:
- Cc (Other, Control)
- Cf (Other, Format)
- Cs (Other, Surrogate), even though they can't appear in Rust strings
- Co (Other, Private Use)
- Cn (Other, Not Assigned)
- Zl (Separator, Line)
- Zp (Separator, Paragraph)
- Zs (Separator, Space), except for the ASCII space `' '` `0x20`
This allows for user-friendly inspection of strings that are not
English (e.g. compare `"\u{e9}\u{e8}\u{ea}"` to `"éèê"`).
Fixes#34318.
CC #34422.
[PEP 3138]: https://www.python.org/dev/peps/pep-3138/
Use the same procedure as Python to determine whether a character is
printable, described in [PEP 3138]. In particular, this means that the
following character classes are escaped:
- Cc (Other, Control)
- Cf (Other, Format)
- Cs (Other, Surrogate), even though they can't appear in Rust strings
- Co (Other, Private Use)
- Cn (Other, Not Assigned)
- Zl (Separator, Line)
- Zp (Separator, Paragraph)
- Zs (Separator, Space), except for the ASCII space `' '` (`0x20`)
This allows for user-friendly inspection of strings that are not
English (e.g. compare `"\u{e9}\u{e8}\u{ea}"` to `"éèê"`).
Fixes#34318.
[PEP 3138]: https://www.python.org/dev/peps/pep-3138/
Although the set of APIs being stabilized this release is relatively small, the
trains keep going! Listed below are the APIs in the standard library which have
either transitioned from unstable to stable or those from unstable to
deprecated.
Stable
* `BTreeMap::{append, split_off}`
* `BTreeSet::{append, split_off}`
* `Cell::get_mut`
* `RefCell::get_mut`
* `BinaryHeap::append`
* `{f32, f64}::{to_degrees, to_radians}` - libcore stabilizations mirroring past
libstd stabilizations
* `Iterator::sum`
* `Iterator::product`
Deprecated
* `{f32, f64}::next_after`
* `{f32, f64}::integer_decode`
* `{f32, f64}::ldexp`
* `{f32, f64}::frexp`
* `num::One`
* `num::Zero`
Added APIs (all unstable)
* `iter::Sum`
* `iter::Product`
* `iter::Step` - a few methods were added to accomodate deprecation of One/Zero
Removed APIs
* `From<Range<T>> for RangeInclusive<T>` - everything about `RangeInclusive` is
unstable
Closes#27739Closes#27752Closes#32526Closes#33444Closes#34152
cc #34529 (new tracking issue)
Implement split_off for BTreeMap and BTreeSet (RFC 509)
Fixes#19986 and refactors common with append methods.
It splits the tree with O(log n) operations and then calculates sizes by traversing the lower one.
CC @gereeter
