`slice_shift_char` splits a `str` into it's leading `char` and the remainder of the `str`. Currently, it returns a `(Option<char>, &str)` such that:
"bar".slice_shift_char() => (Some('b'), "ar")
"ar".slice_shift_char() => (Some('a'), "r")
"r".slice_shift_char() => (Some('r'), "")
"".slice_shift_char() => (None, "")
This is a little odd. Either a `str` can be split into both a head and a tail or it cannot. So the return type should be `Option<(char, &str)>`. With the current behaviour, in the case of the empty string, the `str` returned is meaningless - it is always the empty string.
This PR changes `slice_shift_char` so that:
"bar".slice_shift_char() => Some(('b', "ar"))
"ar".slice_shift_char() => Some(('a', "r"))
"r".slice_shift_char() => Some(('r', ""))
"".slice_shift_char() => None
Following [the collections reform
RFC](https://github.com/rust-lang/rfcs/pull/235),
this commit adds a new `borrow` module to libcore.
The module contains traits for borrowing data (`BorrowFrom` and
`BorrowFromMut`),
generalized cloning (`ToOwned`), and a clone-on-write smartpointer (`Cow`).
This breaks code that referred to variant names in the same namespace as
their enum. Reexport the variants in the old location or alter code to
refer to the new locations:
```
pub enum Foo {
A,
B
}
fn main() {
let a = A;
}
```
=>
```
pub use self::Foo::{A, B};
pub enum Foo {
A,
B
}
fn main() {
let a = A;
}
```
or
```
pub enum Foo {
A,
B
}
fn main() {
let a = Foo::A;
}
```
[breaking-change]
`slice_shift_char` splits a `str` into it's leading `char` and the remainder
of the `str`. Currently, it returns a `(Option<char>, &str)` such that:
"bar".slice_shift_char() => (Some('b'), "ar")
"ar".slice_shift_char() => (Some('a'), "r")
"r".slice_shift_char() => (Some('r'), "")
"".slice_shift_char() => (None, "")
This is a little odd. Either a `str` can be split into both a head and a
tail or it cannot. So the return type should be `Option<(char, &str)>`.
With the current behaviour, in the case of the empty string, the `str`
returned is meaningless - it is always the empty string.
This commit changes slice_shift_char so that:
"bar".slice_shift_char() => Some(('b', "ar"))
"ar".slice_shift_char() => Some(('a', "r"))
"r".slice_shift_char() => Some(('r', ""))
"".slice_shift_char() => None
[breaking-change]
Fix for task in Metabug #18009 (Rebased version of https://github.com/rust-lang/rust/pull/18170)
This changes much of about how RingBuf functions. `lo`, `nelts` are replaced by a more traditional `head` and`tail`. The `Vec<Option<T>>` is replaced by a bare pointer that is managed by the `RingBuf` itself. This also expects the ring buffer to always be size that is a power of 2.
This change also includes a number of new tests to cover the some areas that could be of concern with manual memory management.
The benchmarks have been reworked since the old ones were benchmarking of the Ring buffers growth rather then the actual test.
The unit test suite have been expanded, and exposed some bugs in `fn get()` and `fn get_mut()`
## Benchmark
**Before:**
```
test ring_buf::tests::bench_grow_1025 ... bench: 8919 ns/iter (+/- 87)
test ring_buf::tests::bench_iter_1000 ... bench: 924 ns/iter (+/- 28)
test ring_buf::tests::bench_mut_iter_1000 ... bench: 918 ns/iter (+/- 6)
test ring_buf::tests::bench_new ... bench: 15 ns/iter (+/- 0)
test ring_buf::tests::bench_pop_100 ... bench: 294 ns/iter (+/- 9)
test ring_buf::tests::bench_pop_front_100 ... bench: 948 ns/iter (+/- 32)
test ring_buf::tests::bench_push_back_100 ... bench: 291 ns/iter (+/- 16)
test ring_buf::tests::bench_push_front_100 ... bench: 311 ns/iter (+/- 27
```
**After:**
```
test ring_buf::tests::bench_grow_1025 ... bench: 2209 ns/iter (+/- 169)
test ring_buf::tests::bench_iter_1000 ... bench: 534 ns/iter (+/- 27)
test ring_buf::tests::bench_mut_iter_1000 ... bench: 515 ns/iter (+/- 28)
test ring_buf::tests::bench_new ... bench: 11 ns/iter (+/- 0)
test ring_buf::tests::bench_pop_100 ... bench: 170 ns/iter (+/- 5)
test ring_buf::tests::bench_pop_front_100 ... bench: 171 ns/iter (+/- 11)
test ring_buf::tests::bench_push_back_100 ... bench: 172 ns/iter (+/- 13)
test ring_buf::tests::bench_push_front_100 ... bench: 158 ns/iter (+/- 12)
```
A recent change turned off inheritance for the #[stable] by default, but
failed to catch all the cases where this was being used in std. This
patch fixes that problem.
I found some occurrences of "failure" and "fails" in the documentation. I changed them to "panics" if it means a task panic. Otherwise I left it as is, or changed it to "errors" to clearly distinguish them.
Also, I made a minor fix that is breaking the layout of a module page. "Example" is shown in an irrelevant place from the following page: http://doc.rust-lang.org/std/os/index.html
-Adds unit tests for fn get() and fn get_mut() which are currently untested
-Adds unit tests to verify growth of the ringbuffer when reserve is called.
-Adds unit tests to confirm that dropping of items is correct
Move ringbuf to use a raw buffer instead of Option<T>
This implements a considerable portion of rust-lang/rfcs#369 (tracked in #18640). Some interpretations had to be made in order to get this to work. The breaking changes are listed below:
[breaking-change]
- `core::num::{Num, Unsigned, Primitive}` have been deprecated and their re-exports removed from the `{std, core}::prelude`.
- `core::num::{Zero, One, Bounded}` have been deprecated. Use the static methods on `core::num::{Float, Int}` instead. There is no equivalent to `Zero::is_zero`. Use `(==)` with `{Float, Int}::zero` instead.
- `Signed::abs_sub` has been moved to `std::num::FloatMath`, and is no longer implemented for signed integers.
- `core::num::Signed` has been removed, and its methods have been moved to `core::num::Float` and a new trait, `core::num::SignedInt`. The methods now take the `self` parameter by value.
- `core::num::{Saturating, CheckedAdd, CheckedSub, CheckedMul, CheckedDiv}` have been removed, and their methods moved to `core::num::Int`. Their parameters are now taken by value. This means that
- `std::time::Duration` no longer implements `core::num::{Zero, CheckedAdd, CheckedSub}` instead defining the required methods non-polymorphically.
- `core::num::{zero, one, abs, signum}` have been deprecated. Use their respective methods instead.
- The `core::num::{next_power_of_two, is_power_of_two, checked_next_power_of_two}` functions have been deprecated in favor of methods defined a new trait, `core::num::UnsignedInt`
- `core::iter::{AdditiveIterator, MultiplicativeIterator}` are now only implemented for the built-in numeric types.
- `core::iter::{range, range_inclusive, range_step, range_step_inclusive}` now require `core::num::Int` to be implemented for the type they a re parametrized over.
Throughout the docs, "failure" was replaced with "panics" if it means a
task panic. Otherwise, it remained as is, or changed to "errors" to
clearly differentiate it from a task panic.
Ensured that Extend & FromIterator are implemented for the libcollection.
Removed the fact that FromIterator had to be implemented in order to implement Extend, as it did not make sense for LruCache (it needs to be given a size and there are no Default for LruCache).
Changed the name from Extend to Extendable.
Part of #18424
