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Auto merge of #77639 - jagill:stabilize-slice_partition_at_index, r=Amanieu

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Stabilize slice_partition_at_index

This stabilizes slice_partition_at_index, including renaming `partition_at_index*` -> `select_nth_unstable*`.

Closes #55300

r? `@Amanieu`
This commit is contained in:
bors 2020-10-13 06:33:52 +00:00
commit ec40181913
2 changed files with 69 additions and 31 deletions
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68
library/core/src/slice/mod.rs
View File

@ -2034,6 +2034,50 @@ impl<T> [T] {
sort::quicksort(self, |a, b| f(a).lt(&f(b)));
}
/// Reorder the slice such that the element at `index` is at its final sorted position.
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[rustc_deprecated(since = "1.49.0", reason = "use the select_nth_unstable() instead")]
#[inline]
pub fn partition_at_index(&mut self, index: usize) -> (&mut [T], &mut T, &mut [T])
where
T: Ord,
{
self.select_nth_unstable(index)
}
/// Reorder the slice with a comparator function such that the element at `index` is at its
/// final sorted position.
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[rustc_deprecated(since = "1.49.0", reason = "use select_nth_unstable_by() instead")]
#[inline]
pub fn partition_at_index_by<F>(
&mut self,
index: usize,
compare: F,
) -> (&mut [T], &mut T, &mut [T])
where
F: FnMut(&T, &T) -> Ordering,
{
self.select_nth_unstable_by(index, compare)
}
/// Reorder the slice with a key extraction function such that the element at `index` is at its
/// final sorted position.
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[rustc_deprecated(since = "1.49.0", reason = "use the select_nth_unstable_by_key() instead")]
#[inline]
pub fn partition_at_index_by_key<K, F>(
&mut self,
index: usize,
f: F,
) -> (&mut [T], &mut T, &mut [T])
where
F: FnMut(&T) -> K,
K: Ord,
{
self.select_nth_unstable_by_key(index, f)
}
/// Reorder the slice such that the element at `index` is at its final sorted position.
///
/// This reordering has the additional property that any value at position `i < index` will be
@ -2058,12 +2102,10 @@ impl<T> [T] {
/// # Examples
///
/// ```
/// #![feature(slice_partition_at_index)]
///
/// let mut v = [-5i32, 4, 1, -3, 2];
///
/// // Find the median
/// v.partition_at_index(2);
/// v.select_nth_unstable(2);
///
/// // We are only guaranteed the slice will be one of the following, based on the way we sort
/// // about the specified index.
@ -2072,9 +2114,9 @@ impl<T> [T] {
/// v == [-3, -5, 1, 4, 2] ||
/// v == [-5, -3, 1, 4, 2]);
/// ```
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[stable(feature = "slice_select_nth_unstable", since = "1.49.0")]
#[inline]
pub fn partition_at_index(&mut self, index: usize) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable(&mut self, index: usize) -> (&mut [T], &mut T, &mut [T])
where
T: Ord,
{
@ -2108,12 +2150,10 @@ impl<T> [T] {
/// # Examples
///
/// ```
/// #![feature(slice_partition_at_index)]
///
/// let mut v = [-5i32, 4, 1, -3, 2];
///
/// // Find the median as if the slice were sorted in descending order.
/// v.partition_at_index_by(2, |a, b| b.cmp(a));
/// v.select_nth_unstable_by(2, |a, b| b.cmp(a));
///
/// // We are only guaranteed the slice will be one of the following, based on the way we sort
/// // about the specified index.
@ -2122,9 +2162,9 @@ impl<T> [T] {
/// v == [4, 2, 1, -5, -3] ||
/// v == [4, 2, 1, -3, -5]);
/// ```
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[stable(feature = "slice_select_nth_unstable", since = "1.49.0")]
#[inline]
pub fn partition_at_index_by<F>(
pub fn select_nth_unstable_by<F>(
&mut self,
index: usize,
mut compare: F,
@ -2162,12 +2202,10 @@ impl<T> [T] {
/// # Examples
///
/// ```
/// #![feature(slice_partition_at_index)]
///
/// let mut v = [-5i32, 4, 1, -3, 2];
///
/// // Return the median as if the array were sorted according to absolute value.
/// v.partition_at_index_by_key(2, |a| a.abs());
/// v.select_nth_unstable_by_key(2, |a| a.abs());
///
/// // We are only guaranteed the slice will be one of the following, based on the way we sort
/// // about the specified index.
@ -2176,9 +2214,9 @@ impl<T> [T] {
/// v == [2, 1, -3, 4, -5] ||
/// v == [2, 1, -3, -5, 4]);
/// ```
#[unstable(feature = "slice_partition_at_index", issue = "55300")]
#[stable(feature = "slice_select_nth_unstable", since = "1.49.0")]
#[inline]
pub fn partition_at_index_by_key<K, F>(
pub fn select_nth_unstable_by_key<K, F>(
&mut self,
index: usize,
mut f: F,

32
library/core/tests/slice.rs
View File

@ -1571,7 +1571,7 @@ fn sort_unstable() {
#[test]
#[cfg(not(target_arch = "wasm32"))]
#[cfg_attr(miri, ignore)] // Miri is too slow
fn partition_at_index() {
fn select_nth_unstable() {
use core::cmp::Ordering::{Equal, Greater, Less};
use rand::rngs::StdRng;
use rand::seq::SliceRandom;
@ -1597,7 +1597,7 @@ fn partition_at_index() {
// Sort in default order.
for pivot in 0..len {
let mut v = orig.clone();
v.partition_at_index(pivot);
v.select_nth_unstable(pivot);
assert_eq!(v_sorted[pivot], v[pivot]);
for i in 0..pivot {
@ -1610,7 +1610,7 @@ fn partition_at_index() {
// Sort in ascending order.
for pivot in 0..len {
let mut v = orig.clone();
let (left, pivot, right) = v.partition_at_index_by(pivot, |a, b| a.cmp(b));
let (left, pivot, right) = v.select_nth_unstable_by(pivot, |a, b| a.cmp(b));
assert_eq!(left.len() + right.len(), len - 1);
@ -1633,7 +1633,7 @@ fn partition_at_index() {
for pivot in 0..len {
let mut v = orig.clone();
v.partition_at_index_by(pivot, sort_descending_comparator);
v.select_nth_unstable_by(pivot, sort_descending_comparator);
assert_eq!(v_sorted_descending[pivot], v[pivot]);
for i in 0..pivot {
@ -1654,7 +1654,7 @@ fn partition_at_index() {
}
for pivot in 0..v.len() {
v.partition_at_index_by(pivot, |_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
v.select_nth_unstable_by(pivot, |_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
v.sort();
for i in 0..v.len() {
assert_eq!(v[i], i as i32);
@ -1662,28 +1662,28 @@ fn partition_at_index() {
}
// Should not panic.
[(); 10].partition_at_index(0);
[(); 10].partition_at_index(5);
[(); 10].partition_at_index(9);
[(); 100].partition_at_index(0);
[(); 100].partition_at_index(50);
[(); 100].partition_at_index(99);
[(); 10].select_nth_unstable(0);
[(); 10].select_nth_unstable(5);
[(); 10].select_nth_unstable(9);
[(); 100].select_nth_unstable(0);
[(); 100].select_nth_unstable(50);
[(); 100].select_nth_unstable(99);
let mut v = [0xDEADBEEFu64];
v.partition_at_index(0);
v.select_nth_unstable(0);
assert!(v == [0xDEADBEEF]);
}
#[test]
#[should_panic(expected = "index 0 greater than length of slice")]
fn partition_at_index_zero_length() {
[0i32; 0].partition_at_index(0);
fn select_nth_unstable_zero_length() {
[0i32; 0].select_nth_unstable(0);
}
#[test]
#[should_panic(expected = "index 20 greater than length of slice")]
fn partition_at_index_past_length() {
[0i32; 10].partition_at_index(20);
fn select_nth_unstable_past_length() {
[0i32; 10].select_nth_unstable(20);
}
pub mod memchr {