#[repr(C)]pub struct ArrayVec<A> { /* private fields */ }
Expand description
An array-backed, vector-like data structure.
ArrayVec
has a fixed capacity, equal to the array size.ArrayVec
has a variable length, as you add and remove elements. Attempts to fill the vec beyond its capacity will cause a panic.- All of the vec’s array slots are always initialized in terms of Rust’s memory model. When you remove a element from a location, the old value at that location is replaced with the type’s default value.
The overall API of this type is intended to, as much as possible, emulate
the API of the Vec
type.
§Construction
You can use the array_vec!
macro similarly to how you might use the vec!
macro. Specify the array type, then optionally give all the initial values
you want to have.
let some_ints = array_vec!([i32; 4] => 1, 2, 3);
assert_eq!(some_ints.len(), 3);
The default
for an ArrayVec
is to have a default
array with length 0. The new
method is the same as
calling default
let some_ints = ArrayVec::<[i32; 7]>::default();
assert_eq!(some_ints.len(), 0);
let more_ints = ArrayVec::<[i32; 7]>::new();
assert_eq!(some_ints, more_ints);
If you have an array and want the whole thing so count as being “in” the
new ArrayVec
you can use one of the from
implementations. If you want
part of the array then you can use
from_array_len
:
let some_ints = ArrayVec::from([5, 6, 7, 8]);
assert_eq!(some_ints.len(), 4);
let more_ints = ArrayVec::from_array_len([5, 6, 7, 8], 2);
assert_eq!(more_ints.len(), 2);
let no_ints: ArrayVec<[u8; 5]> = ArrayVec::from_array_empty([1, 2, 3, 4, 5]);
assert_eq!(no_ints.len(), 0);
Implementations§
source§impl<A: Array> ArrayVec<A>
impl<A: Array> ArrayVec<A>
sourcepub fn try_append<'other>(
&mut self,
other: &'other mut Self,
) -> Option<&'other mut Self>
pub fn try_append<'other>( &mut self, other: &'other mut Self, ) -> Option<&'other mut Self>
Move all values from other
into this vec.
If appending would overflow the capacity, Some(other) is returned.
§Example
let mut av = array_vec!([i32; 7] => 1, 2, 3);
let mut av2 = array_vec!([i32; 7] => 4, 5, 6);
av.append(&mut av2);
assert_eq!(av, &[1, 2, 3, 4, 5, 6][..]);
assert_eq!(av2, &[][..]);
let mut av3 = array_vec!([i32; 7] => 7, 8, 9);
assert!(av.try_append(&mut av3).is_some());
assert_eq!(av, &[1, 2, 3, 4, 5, 6][..]);
assert_eq!(av3, &[7, 8, 9][..]);
sourcepub fn as_mut_ptr(&mut self) -> *mut A::Item
pub fn as_mut_ptr(&mut self) -> *mut A::Item
A *mut
pointer to the backing array.
§Safety
This pointer has provenance over the entire backing array.
sourcepub fn as_mut_slice(&mut self) -> &mut [A::Item]
pub fn as_mut_slice(&mut self) -> &mut [A::Item]
Performs a deref_mut
, into unique slice form.
sourcepub fn as_ptr(&self) -> *const A::Item
pub fn as_ptr(&self) -> *const A::Item
A *const
pointer to the backing array.
§Safety
This pointer has provenance over the entire backing array.
sourcepub fn capacity(&self) -> usize
pub fn capacity(&self) -> usize
The capacity of the ArrayVec
.
This is fixed based on the array type, but can’t yet be made a const fn
on Stable Rust.
sourcepub fn drain<R>(&mut self, range: R) -> ArrayVecDrain<'_, A::Item> ⓘwhere
R: RangeBounds<usize>,
pub fn drain<R>(&mut self, range: R) -> ArrayVecDrain<'_, A::Item> ⓘwhere
R: RangeBounds<usize>,
Creates a draining iterator that removes the specified range in the vector and yields the removed items.
§Panics
- If the start is greater than the end
- If the end is past the edge of the vec.
§Example
let mut av = array_vec!([i32; 4] => 1, 2, 3);
let av2: ArrayVec<[i32; 4]> = av.drain(1..).collect();
assert_eq!(av.as_slice(), &[1][..]);
assert_eq!(av2.as_slice(), &[2, 3][..]);
av.drain(..);
assert_eq!(av.as_slice(), &[]);
sourcepub fn into_inner(self) -> A
pub fn into_inner(self) -> A
Returns the inner array of the ArrayVec
.
This returns the full array, even if the ArrayVec
length is currently
less than that.
§Example
let mut favorite_numbers = array_vec!([i32; 5] => 87, 48, 33, 9, 26);
assert_eq!(favorite_numbers.clone().into_inner(), [87, 48, 33, 9, 26]);
favorite_numbers.pop();
assert_eq!(favorite_numbers.into_inner(), [87, 48, 33, 9, 0]);
A use for this function is to build an array from an iterator by first
collecting it into an ArrayVec
.
let arr_vec: ArrayVec<[i32; 10]> = (1..=3).cycle().take(10).collect();
let inner = arr_vec.into_inner();
assert_eq!(inner, [1, 2, 3, 1, 2, 3, 1, 2, 3, 1]);
sourcepub fn extend_from_slice(&mut self, sli: &[A::Item])
pub fn extend_from_slice(&mut self, sli: &[A::Item])
Clone each element of the slice into this ArrayVec
.
§Panics
- If the
ArrayVec
would overflow, this will panic.
sourcepub fn fill<I: IntoIterator<Item = A::Item>>(&mut self, iter: I) -> I::IntoIter
pub fn fill<I: IntoIterator<Item = A::Item>>(&mut self, iter: I) -> I::IntoIter
Fill the vector until its capacity has been reached.
Successively fills unused space in the spare slice of the vector with elements from the iterator. It then returns the remaining iterator without exhausting it. This also allows appending the head of an infinite iterator.
This is an alternative to Extend::extend
method for cases where the
length of the iterator can not be checked. Since this vector can not
reallocate to increase its capacity, it is unclear what to do with
remaining elements in the iterator and the iterator itself. The
interface also provides no way to communicate this to the caller.
§Panics
- If the
next
method of the provided iterator panics.
§Example
let mut av = array_vec!([i32; 4]);
let mut to_inf = av.fill(0..);
assert_eq!(&av[..], [0, 1, 2, 3]);
assert_eq!(to_inf.next(), Some(4));
sourcepub fn from_array_len(data: A, len: usize) -> Self
pub fn from_array_len(data: A, len: usize) -> Self
Wraps up an array and uses the given length as the initial length.
If you want to simply use the full array, use from
instead.
§Panics
- The length specified must be less than or equal to the capacity of the array.
sourcepub fn insert(&mut self, index: usize, item: A::Item)
pub fn insert(&mut self, index: usize, item: A::Item)
Inserts an item at the position given, moving all following elements +1 index.
§Panics
- If
index
>len
- If the capacity is exhausted
§Example
use tinyvec::*;
let mut av = array_vec!([i32; 10] => 1, 2, 3);
av.insert(1, 4);
assert_eq!(av.as_slice(), &[1, 4, 2, 3]);
av.insert(4, 5);
assert_eq!(av.as_slice(), &[1, 4, 2, 3, 5]);
sourcepub fn try_insert(&mut self, index: usize, item: A::Item) -> Option<A::Item>
pub fn try_insert(&mut self, index: usize, item: A::Item) -> Option<A::Item>
Tries to insert an item at the position given, moving all following elements +1 index. Returns back the element if the capacity is exhausted, otherwise returns None.
§Panics
- If
index
>len
§Example
use tinyvec::*;
let mut av = array_vec!([&'static str; 4] => "one", "two", "three");
av.insert(1, "four");
assert_eq!(av.as_slice(), &["one", "four", "two", "three"]);
assert_eq!(av.try_insert(4, "five"), Some("five"));
sourcepub fn push(&mut self, val: A::Item)
pub fn push(&mut self, val: A::Item)
Place an element onto the end of the vec.
§Panics
- If the length of the vec would overflow the capacity.
§Example
let mut av = array_vec!([i32; 2]);
assert_eq!(&av[..], []);
av.push(1);
assert_eq!(&av[..], [1]);
av.push(2);
assert_eq!(&av[..], [1, 2]);
// av.push(3); this would overflow the ArrayVec and panic!
sourcepub fn try_push(&mut self, val: A::Item) -> Option<A::Item>
pub fn try_push(&mut self, val: A::Item) -> Option<A::Item>
Tries to place an element onto the end of the vec.
Returns back the element if the capacity is exhausted,
otherwise returns None.
let mut av = array_vec!([i32; 2]);
assert_eq!(av.as_slice(), []);
assert_eq!(av.try_push(1), None);
assert_eq!(&av[..], [1]);
assert_eq!(av.try_push(2), None);
assert_eq!(&av[..], [1, 2]);
assert_eq!(av.try_push(3), Some(3));
sourcepub fn resize(&mut self, new_len: usize, new_val: A::Item)
pub fn resize(&mut self, new_len: usize, new_val: A::Item)
As resize_with
and it clones the value as the closure.
§Example
let mut av = array_vec!([&str; 10] => "hello");
av.resize(3, "world");
assert_eq!(&av[..], ["hello", "world", "world"]);
let mut av = array_vec!([i32; 10] => 1, 2, 3, 4);
av.resize(2, 0);
assert_eq!(&av[..], [1, 2]);
sourcepub fn resize_with<F: FnMut() -> A::Item>(&mut self, new_len: usize, f: F)
pub fn resize_with<F: FnMut() -> A::Item>(&mut self, new_len: usize, f: F)
Resize the vec to the new length.
If it needs to be longer, it’s filled with repeated calls to the provided function. If it needs to be shorter, it’s truncated.
§Example
let mut av = array_vec!([i32; 10] => 1, 2, 3);
av.resize_with(5, Default::default);
assert_eq!(&av[..], [1, 2, 3, 0, 0]);
let mut av = array_vec!([i32; 10]);
let mut p = 1;
av.resize_with(4, || {
p *= 2;
p
});
assert_eq!(&av[..], [2, 4, 8, 16]);
sourcepub fn retain<F: FnMut(&A::Item) -> bool>(&mut self, acceptable: F)
pub fn retain<F: FnMut(&A::Item) -> bool>(&mut self, acceptable: F)
Walk the vec and keep only the elements that pass the predicate given.
§Example
let mut av = array_vec!([i32; 10] => 1, 1, 2, 3, 3, 4);
av.retain(|&x| x % 2 == 0);
assert_eq!(&av[..], [2, 4]);
sourcepub fn set_len(&mut self, new_len: usize)
pub fn set_len(&mut self, new_len: usize)
Forces the length of the vector to new_len
.
§Panics
- If
new_len
is greater than the vec’s capacity.
§Safety
- This is a fully safe operation! The inactive memory already counts as “initialized” by Rust’s rules.
- Other than “the memory is initialized” there are no other guarantees regarding what you find in the inactive portion of the vec.
sourcepub fn splice<R, I>(
&mut self,
range: R,
replacement: I,
) -> ArrayVecSplice<'_, A, Fuse<I::IntoIter>> ⓘ
pub fn splice<R, I>( &mut self, range: R, replacement: I, ) -> ArrayVecSplice<'_, A, Fuse<I::IntoIter>> ⓘ
Creates a splicing iterator that removes the specified range in the vector, yields the removed items, and replaces them with elements from the provided iterator.
splice
fuses the provided iterator, so elements after the first None
are ignored.
§Panics
- If the start is greater than the end.
- If the end is past the edge of the vec.
- If the provided iterator panics.
- If the new length would overflow the capacity of the array. Because
ArrayVecSplice
adds elements to this vec in its destructor when necessary, this panic would occur when it is dropped.
§Example
use tinyvec::*;
let mut av = array_vec!([i32; 4] => 1, 2, 3);
let av2: ArrayVec<[i32; 4]> = av.splice(1.., 4..=6).collect();
assert_eq!(av.as_slice(), &[1, 4, 5, 6][..]);
assert_eq!(av2.as_slice(), &[2, 3][..]);
av.splice(.., None);
assert_eq!(av.as_slice(), &[]);
sourcepub fn swap_remove(&mut self, index: usize) -> A::Item
pub fn swap_remove(&mut self, index: usize) -> A::Item
Remove an element, swapping the end of the vec into its place.
§Panics
- If the index is out of bounds.
§Example
let mut av = array_vec!([&str; 4] => "foo", "bar", "quack", "zap");
assert_eq!(av.swap_remove(1), "bar");
assert_eq!(&av[..], ["foo", "zap", "quack"]);
assert_eq!(av.swap_remove(0), "foo");
assert_eq!(&av[..], ["quack", "zap"]);
sourcepub fn truncate(&mut self, new_len: usize)
pub fn truncate(&mut self, new_len: usize)
Reduces the vec’s length to the given value.
If the vec is already shorter than the input, nothing happens.
sourcepub fn try_from_array_len(data: A, len: usize) -> Result<Self, A>
pub fn try_from_array_len(data: A, len: usize) -> Result<Self, A>
Wraps an array, using the given length as the starting length.
If you want to use the whole length of the array, you can just use the
From
impl.
§Failure
If the given length is greater than the capacity of the array this will
error, and you’ll get the array back in the Err
.
source§impl<A> ArrayVec<A>
impl<A> ArrayVec<A>
sourcepub const fn from_array_empty(data: A) -> Self
pub const fn from_array_empty(data: A) -> Self
Wraps up an array as a new empty ArrayVec
.
If you want to simply use the full array, use from
instead.
§Examples
This method in particular allows to create values for statics:
static DATA: ArrayVec<[u8; 5]> = ArrayVec::from_array_empty([0; 5]);
assert_eq!(DATA.len(), 0);
But of course it is just an normal empty ArrayVec
:
let mut data = ArrayVec::from_array_empty([1, 2, 3, 4]);
assert_eq!(&data[..], &[]);
data.push(42);
assert_eq!(&data[..], &[42]);
source§impl<A: Array> ArrayVec<A>
impl<A: Array> ArrayVec<A>
sourcepub fn drain_to_vec_and_reserve(&mut self, n: usize) -> Vec<A::Item>
pub fn drain_to_vec_and_reserve(&mut self, n: usize) -> Vec<A::Item>
Drains all elements to a Vec, but reserves additional space
let mut av = array_vec!([i32; 7] => 1, 2, 3);
let v = av.drain_to_vec_and_reserve(10);
assert_eq!(v, &[1, 2, 3]);
assert_eq!(v.capacity(), 13);
sourcepub fn drain_to_vec(&mut self) -> Vec<A::Item>
pub fn drain_to_vec(&mut self) -> Vec<A::Item>
Drains all elements to a Vec
let mut av = array_vec!([i32; 7] => 1, 2, 3);
let v = av.drain_to_vec();
assert_eq!(v, &[1, 2, 3]);
assert_eq!(v.capacity(), 3);
Methods from Deref<Target = [A::Item]>§
sourcepub fn as_str(&self) -> &str
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_str(&self) -> &str
ascii_char
)Views this slice of ASCII characters as a UTF-8 str
.
sourcepub fn as_bytes(&self) -> &[u8]
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_bytes(&self) -> &[u8]
ascii_char
)Views this slice of ASCII characters as a slice of u8
bytes.
1.80.0 · sourcepub fn as_flattened(&self) -> &[T]
pub fn as_flattened(&self) -> &[T]
Takes a &[[T; N]]
, and flattens it to a &[T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
assert_eq!([[1, 2, 3], [4, 5, 6]].as_flattened(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].as_flattened(),
[[1, 2], [3, 4], [5, 6]].as_flattened(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.as_flattened().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.as_flattened().is_empty());
1.80.0 · sourcepub fn as_flattened_mut(&mut self) -> &mut [T]
pub fn as_flattened_mut(&mut self) -> &mut [T]
Takes a &mut [[T; N]]
, and flattens it to a &mut [T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
fn add_5_to_all(slice: &mut [i32]) {
for i in slice {
*i += 5;
}
}
let mut array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
add_5_to_all(array.as_flattened_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);
1.23.0 · sourcepub fn is_ascii(&self) -> bool
pub fn is_ascii(&self) -> bool
Checks if all bytes in this slice are within the ASCII range.
sourcepub fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
)If this slice is_ascii
, returns it as a slice of
ASCII characters, otherwise returns None
.
sourcepub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
🔬This is a nightly-only experimental API. (ascii_char
)
pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
ascii_char
)Converts this slice of bytes into a slice of ASCII characters, without checking whether they’re valid.
§Safety
Every byte in the slice must be in 0..=127
, or else this is UB.
1.23.0 · sourcepub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
Checks that two slices are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
1.23.0 · sourcepub fn make_ascii_uppercase(&mut self)
pub fn make_ascii_uppercase(&mut self)
Converts this slice to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase
.
1.23.0 · sourcepub fn make_ascii_lowercase(&mut self)
pub fn make_ascii_lowercase(&mut self)
Converts this slice to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase
.
1.60.0 · sourcepub fn escape_ascii(&self) -> EscapeAscii<'_>
pub fn escape_ascii(&self) -> EscapeAscii<'_>
Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.
§Examples
let s = b"0\t\r\n'\"\\\x9d";
let escaped = s.escape_ascii().to_string();
assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
1.80.0 · sourcepub fn trim_ascii_start(&self) -> &[u8]
pub fn trim_ascii_start(&self) -> &[u8]
Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b" ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");
1.80.0 · sourcepub fn trim_ascii_end(&self) -> &[u8]
pub fn trim_ascii_end(&self) -> &[u8]
Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b" ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");
1.80.0 · sourcepub fn trim_ascii(&self) -> &[u8]
pub fn trim_ascii(&self) -> &[u8]
Returns a byte slice with leading and trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b" ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");
1.0.0 · sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true
if the slice has a length of 0.
§Examples
let a = [1, 2, 3];
assert!(!a.is_empty());
let b: &[i32] = &[];
assert!(b.is_empty());
1.0.0 · sourcepub fn first(&self) -> Option<&T>
pub fn first(&self) -> Option<&T>
Returns the first element of the slice, or None
if it is empty.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());
let w: &[i32] = &[];
assert_eq!(None, w.first());
1.0.0 · sourcepub fn first_mut(&mut self) -> Option<&mut T>
pub fn first_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the first element of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some(first) = x.first_mut() {
*first = 5;
}
assert_eq!(x, &[5, 1, 2]);
let y: &mut [i32] = &mut [];
assert_eq!(None, y.first_mut());
1.5.0 · sourcepub fn split_first(&self) -> Option<(&T, &[T])>
pub fn split_first(&self) -> Option<(&T, &[T])>
Returns the first and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &[0, 1, 2];
if let Some((first, elements)) = x.split_first() {
assert_eq!(first, &0);
assert_eq!(elements, &[1, 2]);
}
1.5.0 · sourcepub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>
pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the first and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some((first, elements)) = x.split_first_mut() {
*first = 3;
elements[0] = 4;
elements[1] = 5;
}
assert_eq!(x, &[3, 4, 5]);
1.5.0 · sourcepub fn split_last(&self) -> Option<(&T, &[T])>
pub fn split_last(&self) -> Option<(&T, &[T])>
Returns the last and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &[0, 1, 2];
if let Some((last, elements)) = x.split_last() {
assert_eq!(last, &2);
assert_eq!(elements, &[0, 1]);
}
1.5.0 · sourcepub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>
pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the last and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some((last, elements)) = x.split_last_mut() {
*last = 3;
elements[0] = 4;
elements[1] = 5;
}
assert_eq!(x, &[4, 5, 3]);
1.0.0 · sourcepub fn last(&self) -> Option<&T>
pub fn last(&self) -> Option<&T>
Returns the last element of the slice, or None
if it is empty.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());
let w: &[i32] = &[];
assert_eq!(None, w.last());
1.0.0 · sourcepub fn last_mut(&mut self) -> Option<&mut T>
pub fn last_mut(&mut self) -> Option<&mut T>
Returns a mutable reference to the last item in the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_mut() {
*last = 10;
}
assert_eq!(x, &[0, 1, 10]);
let y: &mut [i32] = &mut [];
assert_eq!(None, y.last_mut());
1.77.0 · sourcepub fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
Return an array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());
1.77.0 · sourcepub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Return a mutable array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(first) = x.first_chunk_mut::<2>() {
first[0] = 5;
first[1] = 4;
}
assert_eq!(x, &[5, 4, 2]);
assert_eq!(None, x.first_chunk_mut::<4>());
1.77.0 · sourcepub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
pub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
Return an array reference to the first N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk::<2>() {
assert_eq!(first, &[0, 1]);
assert_eq!(elements, &[2]);
}
assert_eq!(None, x.split_first_chunk::<4>());
1.77.0 · sourcepub fn split_first_chunk_mut<const N: usize>(
&mut self,
) -> Option<(&mut [T; N], &mut [T])>
pub fn split_first_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T; N], &mut [T])>
Return a mutable array reference to the first N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk_mut::<2>() {
first[0] = 3;
first[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[3, 4, 5]);
assert_eq!(None, x.split_first_chunk_mut::<4>());
1.77.0 · sourcepub fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
pub fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
Return an array reference to the last N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk::<2>() {
assert_eq!(elements, &[0]);
assert_eq!(last, &[1, 2]);
}
assert_eq!(None, x.split_last_chunk::<4>());
1.77.0 · sourcepub fn split_last_chunk_mut<const N: usize>(
&mut self,
) -> Option<(&mut [T], &mut [T; N])>
pub fn split_last_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T], &mut [T; N])>
Return a mutable array reference to the last N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk_mut::<2>() {
last[0] = 3;
last[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[5, 3, 4]);
assert_eq!(None, x.split_last_chunk_mut::<4>());
1.77.0 · sourcepub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
Return an array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());
1.77.0 · sourcepub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Return a mutable array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_chunk_mut::<2>() {
last[0] = 10;
last[1] = 20;
}
assert_eq!(x, &[0, 10, 20]);
assert_eq!(None, x.last_chunk_mut::<4>());
1.0.0 · sourcepub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
Returns a reference to an element or subslice depending on the type of index.
- If given a position, returns a reference to the element at that
position or
None
if out of bounds. - If given a range, returns the subslice corresponding to that range,
or
None
if out of bounds.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
1.0.0 · sourcepub fn get_mut<I>(
&mut self,
index: I,
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get_mut<I>(
&mut self,
index: I,
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
1.0.0 · sourcepub unsafe fn get_unchecked<I>(
&self,
index: I,
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked<I>(
&self,
index: I,
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a reference to an element or subslice, without doing bounds checking.
For a safe alternative see get
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get(index).unwrap_unchecked()
. It’s UB
to call .get_unchecked(len)
, even if you immediately convert to a
pointer. And it’s UB to call .get_unchecked(..len + 1)
,
.get_unchecked(..=len)
, or similar.
§Examples
let x = &[1, 2, 4];
unsafe {
assert_eq!(x.get_unchecked(1), &2);
}
1.0.0 · sourcepub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I,
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I,
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a mutable reference to an element or subslice, without doing bounds checking.
For a safe alternative see get_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get_mut(index).unwrap_unchecked()
. It’s
UB to call .get_unchecked_mut(len)
, even if you immediately convert
to a pointer. And it’s UB to call .get_unchecked_mut(..len + 1)
,
.get_unchecked_mut(..=len)
, or similar.
§Examples
let x = &mut [1, 2, 4];
unsafe {
let elem = x.get_unchecked_mut(1);
*elem = 13;
}
assert_eq!(x, &[1, 13, 4]);
1.0.0 · sourcepub fn as_ptr(&self) -> *const T
pub fn as_ptr(&self) -> *const T
Returns a raw pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
The caller must also ensure that the memory the pointer (non-transitively) points to
is never written to (except inside an UnsafeCell
) using this pointer or any pointer
derived from it. If you need to mutate the contents of the slice, use as_mut_ptr
.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
§Examples
let x = &[1, 2, 4];
let x_ptr = x.as_ptr();
unsafe {
for i in 0..x.len() {
assert_eq!(x.get_unchecked(i), &*x_ptr.add(i));
}
}
1.0.0 · sourcepub fn as_mut_ptr(&mut self) -> *mut T
pub fn as_mut_ptr(&mut self) -> *mut T
Returns an unsafe mutable pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
§Examples
let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();
unsafe {
for i in 0..x.len() {
*x_ptr.add(i) += 2;
}
}
assert_eq!(x, &[3, 4, 6]);
1.48.0 · sourcepub fn as_ptr_range(&self) -> Range<*const T>
pub fn as_ptr_range(&self) -> Range<*const T>
Returns the two raw pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_ptr
for warnings on using these pointers. The end pointer
requires extra caution, as it does not point to a valid element in the
slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
It can also be useful to check if a pointer to an element refers to an element of this slice:
let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;
assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));
1.48.0 · sourcepub fn as_mut_ptr_range(&mut self) -> Range<*mut T>
pub fn as_mut_ptr_range(&mut self) -> Range<*mut T>
Returns the two unsafe mutable pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_mut_ptr
for warnings on using these pointers. The end
pointer requires extra caution, as it does not point to a valid element
in the slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
1.0.0 · sourcepub fn swap(&mut self, a: usize, b: usize)
pub fn swap(&mut self, a: usize, b: usize)
Swaps two elements in the slice.
If a
equals to b
, it’s guaranteed that elements won’t change value.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Panics
Panics if a
or b
are out of bounds.
§Examples
let mut v = ["a", "b", "c", "d", "e"];
v.swap(2, 4);
assert!(v == ["a", "b", "e", "d", "c"]);
sourcepub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
🔬This is a nightly-only experimental API. (slice_swap_unchecked
)
pub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
slice_swap_unchecked
)Swaps two elements in the slice, without doing bounds checking.
For a safe alternative see swap
.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Safety
Calling this method with an out-of-bounds index is undefined behavior.
The caller has to ensure that a < self.len()
and b < self.len()
.
§Examples
#![feature(slice_swap_unchecked)]
let mut v = ["a", "b", "c", "d"];
// SAFETY: we know that 1 and 3 are both indices of the slice
unsafe { v.swap_unchecked(1, 3) };
assert!(v == ["a", "d", "c", "b"]);
1.0.0 · sourcepub fn reverse(&mut self)
pub fn reverse(&mut self)
Reverses the order of elements in the slice, in place.
§Examples
let mut v = [1, 2, 3];
v.reverse();
assert!(v == [3, 2, 1]);
1.0.0 · sourcepub fn iter(&self) -> Iter<'_, T>
pub fn iter(&self) -> Iter<'_, T>
Returns an iterator over the slice.
The iterator yields all items from start to end.
§Examples
let x = &[1, 2, 4];
let mut iterator = x.iter();
assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);
1.0.0 · sourcepub fn iter_mut(&mut self) -> IterMut<'_, T>
pub fn iter_mut(&mut self) -> IterMut<'_, T>
Returns an iterator that allows modifying each value.
The iterator yields all items from start to end.
§Examples
let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
*elem += 2;
}
assert_eq!(x, &[3, 4, 6]);
1.0.0 · sourcepub fn windows(&self, size: usize) -> Windows<'_, T>
pub fn windows(&self, size: usize) -> Windows<'_, T>
Returns an iterator over all contiguous windows of length
size
. The windows overlap. If the slice is shorter than
size
, the iterator returns no values.
§Panics
Panics if size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.windows(3);
assert_eq!(iter.next().unwrap(), &['l', 'o', 'r']);
assert_eq!(iter.next().unwrap(), &['o', 'r', 'e']);
assert_eq!(iter.next().unwrap(), &['r', 'e', 'm']);
assert!(iter.next().is_none());
If the slice is shorter than size
:
let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());
There’s no windows_mut
, as that existing would let safe code violate the
“only one &mut
at a time to the same thing” rule. However, you can sometimes
use Cell::as_slice_of_cells
in
conjunction with windows
to accomplish something similar:
use std::cell::Cell;
let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
Cell::swap(&w[0], &w[2]);
}
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);
1.0.0 · sourcepub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See chunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and rchunks
for the same iterator but starting at the end of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());
1.0.0 · sourcepub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>
pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See chunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and rchunks_mut
for the same iterator but starting at
the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 3]);
1.31.0 · sourcepub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks
.
See chunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and rchunks_exact
for the same iterator but starting at the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
1.31.0 · sourcepub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>
pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See chunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and rchunks_exact_mut
for the same iterator but starting at the end of
the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
sourcepub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed
sourcepub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);
If you expect the slice to be an exact multiple, you can combine
let
-else
with an empty slice pattern:
#![feature(slice_as_chunks)]
let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
panic!("slice didn't have even length")
};
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);
sourcepub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
sourcepub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
🔬This is a nightly-only experimental API. (array_chunks
)
pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
array_chunks
)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are array references and do not overlap. If N
does not divide the
length of the slice, then the last up to N-1
elements will be omitted and can be
retrieved from the remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
sourcepub unsafe fn as_chunks_unchecked_mut<const N: usize>(
&mut self,
) -> &mut [[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub unsafe fn as_chunks_unchecked_mut<const N: usize>( &mut self, ) -> &mut [[T; N]]
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &mut [char] = &mut ['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &mut [[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked_mut() };
chunks[0] = ['L'];
assert_eq!(chunks, &[['L'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &mut [[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked_mut() };
chunks[1] = ['a', 'x', '?'];
assert_eq!(slice, &['L', 'o', 'r', 'a', 'x', '?']);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked_mut() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked_mut() // Zero-length chunks are never allowed
sourcepub fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (chunks, remainder) = v.as_chunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 9]);
sourcepub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (remainder, chunks) = v.as_rchunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[9, 1, 1, 2, 2]);
sourcepub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>
🔬This is a nightly-only experimental API. (array_chunks
)
pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>
array_chunks
)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable array references and do not overlap. If N
does not divide
the length of the slice, then the last up to N-1
elements will be omitted and
can be retrieved from the into_remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact_mut
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.array_chunks_mut() {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
sourcepub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
🔬This is a nightly-only experimental API. (array_windows
)
pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
array_windows
)Returns an iterator over overlapping windows of N
elements of a slice,
starting at the beginning of the slice.
This is the const generic equivalent of windows
.
If N
is greater than the size of the slice, it will return no windows.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());
1.31.0 · sourcepub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See rchunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and chunks
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());
1.31.0 · sourcepub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>
pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See rchunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and chunks_mut
for the same iterator but starting at the
beginning of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);
1.31.0 · sourcepub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
end of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of rchunks
.
See rchunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and chunks_exact
for the same iterator but starting at the beginning of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);
1.31.0 · sourcepub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>
pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See rchunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and chunks_exact_mut
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);
1.77.0 · sourcepub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by(|a, b| a <= b);
assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);
1.77.0 · sourcepub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
pub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by_mut(|a, b| a == b);
assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
assert_eq!(iter.next(), Some(&mut [3, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by_mut(|a, b| a <= b);
assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3, 4][..]));
assert_eq!(iter.next(), None);
1.0.0 · sourcepub fn split_at(&self, mid: usize) -> (&[T], &[T])
pub fn split_at(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_checked
.
§Examples
let v = [1, 2, 3, 4, 5, 6];
{
let (left, right) = v.split_at(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
1.0.0 · sourcepub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_mut_checked
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_at_mut(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
1.79.0 · sourcepub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
let v = [1, 2, 3, 4, 5, 6];
unsafe {
let (left, right) = v.split_at_unchecked(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
1.79.0 · sourcepub unsafe fn split_at_mut_unchecked(
&mut self,
mid: usize,
) -> (&mut [T], &mut [T])
pub unsafe fn split_at_mut_unchecked( &mut self, mid: usize, ) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
unsafe {
let (left, right) = v.split_at_mut_unchecked(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
1.80.0 · sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
pub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
Divides one slice into two at an index, returning None
if the slice is
too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
let v = [1, -2, 3, -4, 5, -6];
{
let (left, right) = v.split_at_checked(0).unwrap();
assert_eq!(left, []);
assert_eq!(right, [1, -2, 3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(2).unwrap();
assert_eq!(left, [1, -2]);
assert_eq!(right, [3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(6).unwrap();
assert_eq!(left, [1, -2, 3, -4, 5, -6]);
assert_eq!(right, []);
}
assert_eq!(None, v.split_at_checked(7));
1.80.0 · sourcepub fn split_at_mut_checked(
&mut self,
mid: usize,
) -> Option<(&mut [T], &mut [T])>
pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut [T], &mut [T])>
Divides one mutable slice into two at an index, returning None
if the
slice is too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
if let Some((left, right)) = v.split_at_mut_checked(2) {
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
assert_eq!(None, v.split_at_mut_checked(7));
1.0.0 · sourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F>
pub fn split<F>(&self, pred: F) -> Split<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
. The matched element is not contained in the subslices.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:
let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());
If two matched elements are directly adjacent, an empty slice will be present between them:
let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
1.0.0 · sourcepub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F>
pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
. The matched element is not contained in the subslices.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_mut(|num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 1]);
1.51.0 · sourcepub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
. The matched element is contained in the end of the previous
subslice as a terminator.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.
let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());
1.51.0 · sourcepub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>
pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
. The matched element is contained in the previous
subslice as a terminator.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
let terminator_idx = group.len()-1;
group[terminator_idx] = 1;
}
assert_eq!(v, [10, 40, 1, 20, 1, 1]);
1.27.0 · sourcepub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>
pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
, starting at the end of the slice and working backwards.
The matched element is not contained in the subslices.
§Examples
let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);
assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);
As with split()
, if the first or last element is matched, an empty
slice will be the first (or last) item returned by the iterator.
let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);
1.27.0 · sourcepub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F>
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
, starting at the end of the slice and working
backwards. The matched element is not contained in the subslices.
§Examples
let mut v = [100, 400, 300, 200, 600, 500];
let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
count += 1;
group[0] = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);
1.0.0 · sourcepub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once by numbers divisible by 3 (i.e., [10, 40]
,
[20, 60, 50]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.splitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
1.0.0 · sourcepub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F>
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.splitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);
1.0.0 · sourcepub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once, starting from the end, by numbers divisible
by 3 (i.e., [50]
, [10, 40, 30, 20]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.rsplitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
1.0.0 · sourcepub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut s = [10, 40, 30, 20, 60, 50];
for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);
sourcepub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
)Splits the slice on the first element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.split_once(|&x| x == 2), Some((
&[1][..],
&[3, 2, 4][..]
)));
assert_eq!(s.split_once(|&x| x == 0), None);
sourcepub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
)Splits the slice on the last element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.rsplit_once(|&x| x == 2), Some((
&[1, 2, 3][..],
&[4][..]
)));
assert_eq!(s.rsplit_once(|&x| x == 0), None);
1.0.0 · sourcepub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
pub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
Returns true
if the slice contains an element with the given value.
This operation is O(n).
Note that if you have a sorted slice, binary_search
may be faster.
§Examples
let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));
If you do not have a &T
, but some other value that you can compare
with one (for example, String
implements PartialEq<str>
), you can
use iter().any
:
let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));
1.0.0 · sourcepub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a prefix of the slice or equal to the slice.
§Examples
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(v.starts_with(&v));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));
1.0.0 · sourcepub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a suffix of the slice or equal to the slice.
§Examples
let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(v.ends_with(&v));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));
1.51.0 · sourcepub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
Returns a subslice with the prefix removed.
If the slice starts with prefix
, returns the subslice after the prefix, wrapped in Some
.
If prefix
is empty, simply returns the original slice. If prefix
is equal to the
original slice, returns an empty slice.
If the slice does not start with prefix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);
let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
Some(b"llo".as_ref()));
1.51.0 · sourcepub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
Returns a subslice with the suffix removed.
If the slice ends with suffix
, returns the subslice before the suffix, wrapped in Some
.
If suffix
is empty, simply returns the original slice. If suffix
is equal to the
original slice, returns an empty slice.
If the slice does not end with suffix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);
1.0.0 · sourcepub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
pub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
Binary searches this slice for a given element. If the slice is not sorted, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search_by
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
assert_eq!(s.binary_search(&13), Ok(9));
assert_eq!(s.binary_search(&4), Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });
If you want to find that whole range of matching items, rather than
an arbitrary matching one, that can be done using partition_point
:
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));
assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));
// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));
If you want to insert an item to a sorted vector, while maintaining
sort order, consider using partition_point
:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
// If `num` is unique, `s.partition_point(|&x| x < num)` (with `<`) is equivalent to
// `s.binary_search(&num).unwrap_or_else(|x| x)`, but using `<=` will allow `insert`
// to shift less elements.
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
1.0.0 · sourcepub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
Binary searches this slice with a comparator function.
The comparator function should return an order code that indicates
whether its argument is Less
, Equal
or Greater
the desired
target.
If the slice is not sorted or if the comparator function does not
implement an order consistent with the sort order of the underlying
slice, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });
1.10.0 · sourcepub fn binary_search_by_key<'a, B, F>(
&'a self,
b: &B,
f: F,
) -> Result<usize, usize>
pub fn binary_search_by_key<'a, B, F>( &'a self, b: &B, f: F, ) -> Result<usize, usize>
Binary searches this slice with a key extraction function.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
If the slice is not sorted by the key, the returned result is
unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by
, and partition_point
.
§Examples
Looks up a series of four elements in a slice of pairs sorted by
their second elements. The first is found, with a uniquely
determined position; the second and third are not found; the
fourth could match any position in [1, 4]
.
let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
(1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
(1, 21), (2, 34), (4, 55)];
assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });
1.20.0 · sourcepub fn sort_unstable(&mut self)where
T: Ord,
pub fn sort_unstable(&mut self)where
T: Ord,
Sorts the slice without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
If T: Ord
does not implement a total order the resulting order is unspecified. All
original elements will remain in the slice and any possible modifications via interior
mutability are observed in the input. Same is true if T: Ord
panics.
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
If T: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort_unstable();
assert!(v == [-5, -3, 1, 2, 4]);
1.20.0 · sourcepub fn sort_unstable_by<F>(&mut self, compare: F)
pub fn sort_unstable_by<F>(&mut self, compare: F)
Sorts the slice with a comparator function, without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
The comparator function should define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified.
If the comparator function does not implement a total order the resulting order is
unspecified. All original elements will remain in the slice and any possible modifications
via interior mutability are observed in the input. Same is true if the comparator function
panics. A total order (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
If T: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
1.20.0 · sourcepub fn sort_unstable_by_key<K, F>(&mut self, f: F)
pub fn sort_unstable_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
If K: Ord
does not implement a total order the resulting order is unspecified.
All original elements will remain in the slice and any possible modifications via interior
mutability are observed in the input. Same is true if K: Ord
panics.
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
If K: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_unstable_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
1.49.0 · sourcepub fn select_nth_unstable(
&mut self,
index: usize,
) -> (&mut [T], &mut T, &mut [T])where
T: Ord,
pub fn select_nth_unstable(
&mut self,
index: usize,
) -> (&mut [T], &mut T, &mut [T])where
T: Ord,
Reorder the slice such that the element at index
after the reordering is at its final
sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
. Additionally, this reordering is
unstable (i.e. any number of equal elements may end up at position index
), in-place (i.e.
does not allocate), and runs in O(n) time. This function is also known as “kth element”
in other libraries.
It returns a triplet of the following from the reordered slice: the subslice prior to
index
, the element at index
, and the subslice after index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and
greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
It is typically faster than stable sorting, except in a few special cases, e.g., when the
slice is nearly fully sorted, where slice::sort
may be faster.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 2, -3, 1];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median.
let (lesser, median, greater) = v.select_nth_unstable(2);
assert!(lesser == [-3, -5] || lesser == [-5, -3]);
assert_eq!(median, &mut 1);
assert!(greater == [4, 2] || greater == [2, 4]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
v == [-5, -3, 1, 2, 4] ||
v == [-3, -5, 1, 4, 2] ||
v == [-5, -3, 1, 4, 2]);
1.49.0 · sourcepub fn select_nth_unstable_by<F>(
&mut self,
index: usize,
compare: F,
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by<F>( &mut self, index: usize, compare: F, ) -> (&mut [T], &mut T, &mut [T])
Reorder the slice with a comparator function such that the element at index
after the
reordering is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the comparator function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time. This
function is also known as “kth element” in other libraries.
It returns a triplet of the following from the slice reordered according to the provided
comparator function: the subslice prior to index
, the element at index
, and the subslice
after index
; accordingly, the values in those two subslices will respectively all be
less-than-or-equal-to and greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
It is typically faster than stable sorting, except in a few special cases, e.g., when the
slice is nearly fully sorted, where slice::sort
may be faster.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 2, -3, 1];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted in descending order.
let (lesser, median, greater) = v.select_nth_unstable_by(2, |a, b| b.cmp(a));
assert!(lesser == [4, 2] || lesser == [2, 4]);
assert_eq!(median, &mut 1);
assert!(greater == [-3, -5] || greater == [-5, -3]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
v == [2, 4, 1, -3, -5] ||
v == [4, 2, 1, -5, -3] ||
v == [4, 2, 1, -3, -5]);
1.49.0 · sourcepub fn select_nth_unstable_by_key<K, F>(
&mut self,
index: usize,
f: F,
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by_key<K, F>( &mut self, index: usize, f: F, ) -> (&mut [T], &mut T, &mut [T])
Reorder the slice with a key extraction function such that the element at index
after the
reordering is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the key extraction function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time. This
function is also known as “kth element” in other libraries.
It returns a triplet of the following from the slice reordered according to the provided key
extraction function: the subslice prior to index
, the element at index
, and the subslice
after index
; accordingly, the values in those two subslices will respectively all be
less-than-or-equal-to and greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
It is typically faster than stable sorting, except in a few special cases, e.g., when the
slice is nearly fully sorted, where slice::sort
may be faster.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted according to absolute value.
let (lesser, median, greater) = v.select_nth_unstable_by_key(2, |a| a.abs());
assert!(lesser == [1, 2] || lesser == [2, 1]);
assert_eq!(median, &mut -3);
assert!(greater == [4, -5] || greater == [-5, 4]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
v == [1, 2, -3, -5, 4] ||
v == [2, 1, -3, 4, -5] ||
v == [2, 1, -3, -5, 4]);
sourcepub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
slice_partition_dedup
)Moves all consecutive repeated elements to the end of the slice according to the
PartialEq
trait implementation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];
let (dedup, duplicates) = slice.partition_dedup();
assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);
sourcepub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
slice_partition_dedup
)Moves all but the first of consecutive elements to the end of the slice satisfying a given equality relation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
The same_bucket
function is passed references to two elements from the slice and
must determine if the elements compare equal. The elements are passed in opposite order
from their order in the slice, so if same_bucket(a, b)
returns true
, a
is moved
at the end of the slice.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];
let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);
sourcepub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
slice_partition_dedup
)Moves all but the first of consecutive elements to the end of the slice that resolve to the same key.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];
let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);
assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);
1.26.0 · sourcepub fn rotate_left(&mut self, mid: usize)
pub fn rotate_left(&mut self, mid: usize)
Rotates the slice in-place such that the first mid
elements of the
slice move to the end while the last self.len() - mid
elements move to
the front. After calling rotate_left
, the element previously at index
mid
will become the first element in the slice.
§Panics
This function will panic if mid
is greater than the length of the
slice. Note that mid == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
Rotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
1.26.0 · sourcepub fn rotate_right(&mut self, k: usize)
pub fn rotate_right(&mut self, k: usize)
Rotates the slice in-place such that the first self.len() - k
elements of the slice move to the end while the last k
elements move
to the front. After calling rotate_right
, the element previously at
index self.len() - k
will become the first element in the slice.
§Panics
This function will panic if k
is greater than the length of the
slice. Note that k == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
Rotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
1.50.0 · sourcepub fn fill(&mut self, value: T)where
T: Clone,
pub fn fill(&mut self, value: T)where
T: Clone,
Fills self
with elements by cloning value
.
§Examples
let mut buf = vec![0; 10];
buf.fill(1);
assert_eq!(buf, vec![1; 10]);
1.51.0 · sourcepub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
pub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
Fills self
with elements returned by calling a closure repeatedly.
This method uses a closure to create new values. If you’d rather
Clone
a given value, use fill
. If you want to use the Default
trait to generate values, you can pass Default::default
as the
argument.
§Examples
let mut buf = vec![1; 10];
buf.fill_with(Default::default);
assert_eq!(buf, vec![0; 10]);
1.7.0 · sourcepub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
pub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
Copies the elements from src
into self
.
The length of src
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Cloning two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use clone_from_slice
on a
single slice will result in a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].clone_from_slice(&slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.clone_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
1.9.0 · sourcepub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
pub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
Copies all elements from src
into self
, using a memcpy.
The length of src
must be the same as self
.
If T
does not implement Copy
, use clone_from_slice
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Copying two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use copy_from_slice
on a
single slice will result in a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].copy_from_slice(&slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.copy_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
1.37.0 · sourcepub fn copy_within<R>(&mut self, src: R, dest: usize)
pub fn copy_within<R>(&mut self, src: R, dest: usize)
Copies elements from one part of the slice to another part of itself, using a memmove.
src
is the range within self
to copy from. dest
is the starting
index of the range within self
to copy to, which will have the same
length as src
. The two ranges may overlap. The ends of the two ranges
must be less than or equal to self.len()
.
§Panics
This function will panic if either range exceeds the end of the slice,
or if the end of src
is before the start.
§Examples
Copying four bytes within a slice:
let mut bytes = *b"Hello, World!";
bytes.copy_within(1..5, 8);
assert_eq!(&bytes, b"Hello, Wello!");
1.27.0 · sourcepub fn swap_with_slice(&mut self, other: &mut [T])
pub fn swap_with_slice(&mut self, other: &mut [T])
Swaps all elements in self
with those in other
.
The length of other
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Example
Swapping two elements across slices:
let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];
slice1.swap_with_slice(&mut slice2[2..]);
assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);
Rust enforces that there can only be one mutable reference to a
particular piece of data in a particular scope. Because of this,
attempting to use swap_with_slice
on a single slice will result in
a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
mutable sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.swap_with_slice(&mut right[1..]);
}
assert_eq!(slice, [4, 5, 3, 1, 2]);
1.30.0 · sourcepub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
1.30.0 · sourcepub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
Transmute the mutable slice to a mutable slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
sourcepub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
🔬This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
portable_simd
)Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
This is a safe wrapper around slice::align_to
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.middle.is_empty()
despiteself.len() >= 3 * LANES
.suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code, then this can at most cause incorrect logic, not unsoundness.
§Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like LANES == 3
.
§Examples
#![feature(portable_simd)]
use core::simd::prelude::*;
let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle
// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);
fn basic_simd_sum(x: &[f32]) -> f32 {
use std::ops::Add;
let (prefix, middle, suffix) = x.as_simd();
let sums = f32x4::from_array([
prefix.iter().copied().sum(),
0.0,
0.0,
suffix.iter().copied().sum(),
]);
let sums = middle.iter().copied().fold(sums, f32x4::add);
sums.reduce_sum()
}
let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);
sourcepub fn as_simd_mut<const LANES: usize>(
&mut self,
) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
🔬This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd_mut<const LANES: usize>( &mut self, ) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
portable_simd
)Split a mutable slice into a mutable prefix, a middle of aligned SIMD types, and a mutable suffix.
This is a safe wrapper around slice::align_to_mut
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.middle.is_empty()
despiteself.len() >= 3 * LANES
.suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code, then this can at most cause incorrect logic, not unsoundness.
This is the mutable version of slice::as_simd
; see that for examples.
§Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like LANES == 3
.
sourcepub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
🔬This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
is_sorted
)Checks if the elements of this slice are sorted.
That is, for each element a
and its following element b
, a <= b
must hold. If the
slice yields exactly zero or one element, true
is returned.
Note that if Self::Item
is only PartialOrd
, but not Ord
, the above definition
implies that this function returns false
if any two consecutive items are not
comparable.
§Examples
#![feature(is_sorted)]
let empty: [i32; 0] = [];
assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!([0].is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, f32::NAN].is_sorted());
sourcepub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
🔬This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
is_sorted
)Checks if the elements of this slice are sorted using the given comparator function.
Instead of using PartialOrd::partial_cmp
, this function uses the given compare
function to determine whether two elements are to be considered in sorted order.
§Examples
#![feature(is_sorted)]
assert!([1, 2, 2, 9].is_sorted_by(|a, b| a <= b));
assert!(![1, 2, 2, 9].is_sorted_by(|a, b| a < b));
assert!([0].is_sorted_by(|a, b| true));
assert!([0].is_sorted_by(|a, b| false));
let empty: [i32; 0] = [];
assert!(empty.is_sorted_by(|a, b| false));
assert!(empty.is_sorted_by(|a, b| true));
sourcepub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
🔬This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
is_sorted
)Checks if the elements of this slice are sorted using the given key extraction function.
Instead of comparing the slice’s elements directly, this function compares the keys of the
elements, as determined by f
. Apart from that, it’s equivalent to is_sorted
; see its
documentation for more information.
§Examples
#![feature(is_sorted)]
assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
1.52.0 · sourcepub fn partition_point<P>(&self, pred: P) -> usize
pub fn partition_point<P>(&self, pred: P) -> usize
Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).
The slice is assumed to be partitioned according to the given predicate.
This means that all elements for which the predicate returns true are at the start of the slice
and all elements for which the predicate returns false are at the end.
For example, [7, 15, 3, 5, 4, 12, 6]
is partitioned under the predicate x % 2 != 0
(all odd numbers are at the start, all even at the end).
If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.
See also binary_search
, binary_search_by
, and binary_search_by_key
.
§Examples
let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);
assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));
If all elements of the slice match the predicate, including if the slice is empty, then the length of the slice will be returned:
let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);
If you want to insert an item to a sorted vector, while maintaining sort order:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
sourcepub fn take<'a, R>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take<'a, R>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
slice_take
)Removes the subslice corresponding to the given range and returns a reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut first_three = slice.take(..3).unwrap();
assert_eq!(slice, &['d']);
assert_eq!(first_three, &['a', 'b', 'c']);
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut tail = slice.take(2..).unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(tail, &['c', 'd']);
Getting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take(5..));
assert_eq!(None, slice.take(..5));
assert_eq!(None, slice.take(..=4));
let expected: &[char] = &['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take(..4));
sourcepub fn take_mut<'a, R>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_mut<'a, R>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
slice_take
)Removes the subslice corresponding to the given range and returns a mutable reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut first_three = slice.take_mut(..3).unwrap();
assert_eq!(slice, &mut ['d']);
assert_eq!(first_three, &mut ['a', 'b', 'c']);
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut tail = slice.take_mut(2..).unwrap();
assert_eq!(slice, &mut ['a', 'b']);
assert_eq!(tail, &mut ['c', 'd']);
Getting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take_mut(5..));
assert_eq!(None, slice.take_mut(..5));
assert_eq!(None, slice.take_mut(..=4));
let expected: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take_mut(..4));
sourcepub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
)Removes the first element of the slice and returns a reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c'];
let first = slice.take_first().unwrap();
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'a');
sourcepub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
)Removes the first element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let first = slice.take_first_mut().unwrap();
*first = 'd';
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'d');
sourcepub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
)Removes the last element of the slice and returns a reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c'];
let last = slice.take_last().unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'c');
sourcepub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
)Removes the last element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let last = slice.take_last_mut().unwrap();
*last = 'd';
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'d');
sourcepub unsafe fn get_many_unchecked_mut<const N: usize>(
&mut self,
indices: [usize; N],
) -> [&mut T; N]
🔬This is a nightly-only experimental API. (get_many_mut
)
pub unsafe fn get_many_unchecked_mut<const N: usize>( &mut self, indices: [usize; N], ) -> [&mut T; N]
get_many_mut
)Returns mutable references to many indices at once, without doing any checks.
For a safe alternative see get_many_mut
.
§Safety
Calling this method with overlapping or out-of-bounds indices is undefined behavior even if the resulting references are not used.
§Examples
#![feature(get_many_mut)]
let x = &mut [1, 2, 4];
unsafe {
let [a, b] = x.get_many_unchecked_mut([0, 2]);
*a *= 10;
*b *= 100;
}
assert_eq!(x, &[10, 2, 400]);
sourcepub fn get_many_mut<const N: usize>(
&mut self,
indices: [usize; N],
) -> Result<[&mut T; N], GetManyMutError<N>>
🔬This is a nightly-only experimental API. (get_many_mut
)
pub fn get_many_mut<const N: usize>( &mut self, indices: [usize; N], ) -> Result<[&mut T; N], GetManyMutError<N>>
get_many_mut
)Returns mutable references to many indices at once.
Returns an error if any index is out-of-bounds, or if the same index was passed more than once.
§Examples
#![feature(get_many_mut)]
let v = &mut [1, 2, 3];
if let Ok([a, b]) = v.get_many_mut([0, 2]) {
*a = 413;
*b = 612;
}
assert_eq!(v, &[413, 2, 612]);
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
)
pub fn sort_floats(&mut self)
sort_floats
)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f64::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
1.79.0 · sourcepub fn utf8_chunks(&self) -> Utf8Chunks<'_>
pub fn utf8_chunks(&self) -> Utf8Chunks<'_>
Creates an iterator over the contiguous valid UTF-8 ranges of this slice, and the non-UTF-8 fragments in between.
§Examples
This function formats arbitrary but mostly-UTF-8 bytes into Rust source
code in the form of a C-string literal (c"..."
).
use std::fmt::Write as _;
pub fn cstr_literal(bytes: &[u8]) -> String {
let mut repr = String::new();
repr.push_str("c\"");
for chunk in bytes.utf8_chunks() {
for ch in chunk.valid().chars() {
// Escapes \0, \t, \r, \n, \\, \', \", and uses \u{...} for non-printable characters.
write!(repr, "{}", ch.escape_debug()).unwrap();
}
for byte in chunk.invalid() {
write!(repr, "\\x{:02X}", byte).unwrap();
}
}
repr.push('"');
repr
}
fn main() {
let lit = cstr_literal(b"\xferris the \xf0\x9f\xa6\x80\x07");
let expected = stringify!(c"\xFErris the 🦀\u{7}");
assert_eq!(lit, expected);
}
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
)
pub fn sort_floats(&mut self)
sort_floats
)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f32::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> Vec<u8>
pub fn to_ascii_uppercase(&self) -> Vec<u8>
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase
.
1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> Vec<u8>
pub fn to_ascii_lowercase(&self) -> Vec<u8>
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase
.
1.0.0 · sourcepub fn sort(&mut self)where
T: Ord,
pub fn sort(&mut self)where
T: Ord,
Sorts the slice, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
If T: Ord
does not implement a total order the resulting order is unspecified. All
original elements will remain in the slice and any possible modifications via interior
mutability are observed in the input. Same is true if T: Ord
panics.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory. See
sort_unstable
. The exception are partially sorted slices, which
may be better served with slice::sort
.
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
If T: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort();
assert!(v == [-5, -3, 1, 2, 4]);
1.0.0 · sourcepub fn sort_by<F>(&mut self, compare: F)
pub fn sort_by<F>(&mut self, compare: F)
Sorts the slice with a comparator function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
The comparator function should define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified.
If the comparator function does not implement a total order the resulting order is
unspecified. All original elements will remain in the slice and any possible modifications
via interior mutability are observed in the input. Same is true if the comparator function
panics. A total order (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
If T: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
1.7.0 · sourcepub fn sort_by_key<K, F>(&mut self, f: F)
pub fn sort_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).
If K: Ord
does not implement a total order the resulting order is unspecified.
All original elements will remain in the slice and any possible modifications via interior
mutability are observed in the input. Same is true if K: Ord
panics.
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
If K: Ord
does not implement a total order, the implementation may panic.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
1.34.0 · sourcepub fn sort_by_cached_key<K, F>(&mut self, f: F)
pub fn sort_by_cached_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(m * n + n * log(n)) worst-case, where the key function is O(m).
During sorting, the key function is called at most once per element, by using temporary storage to remember the results of key evaluation. The order of calls to the key function is unspecified and may change in future versions of the standard library.
If K: Ord
does not implement a total order the resulting order is unspecified.
All original elements will remain in the slice and any possible modifications via interior
mutability are observed in the input. Same is true if K: Ord
panics.
For simple key functions (e.g., functions that are property accesses or basic operations),
sort_by_key
is likely to be faster.
§Current implementation
The current implementation is based on instruction-parallel-network sort by Lukas Bergdoll, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on fully sorted and reversed inputs. And O(k * log(n)) where k is the number of distinct elements in the input. It leverages superscalar out-of-order execution capabilities commonly found in CPUs, to efficiently perform the operation.
In the worst case, the algorithm allocates temporary storage in a Vec<(K, usize)>
the
length of the slice.
§Examples
let mut v = [-5i32, 4, 32, -3, 2];
v.sort_by_cached_key(|k| k.to_string());
assert!(v == [-3, -5, 2, 32, 4]);
1.0.0 · sourcepub fn to_vec(&self) -> Vec<T>where
T: Clone,
pub fn to_vec(&self) -> Vec<T>where
T: Clone,
Copies self
into a new Vec
.
§Examples
let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.
sourcepub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
allocator_api
)Copies self
into a new Vec
with an allocator.
§Examples
#![feature(allocator_api)]
use std::alloc::System;
let s = [10, 40, 30];
let x = s.to_vec_in(System);
// Here, `s` and `x` can be modified independently.
1.0.0 · sourcepub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output
pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output
Flattens a slice of T
into a single value Self::Output
.
§Examples
assert_eq!(["hello", "world"].concat(), "helloworld");
assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);
1.3.0 · sourcepub fn join<Separator>(
&self,
sep: Separator,
) -> <[T] as Join<Separator>>::Output
pub fn join<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output
Flattens a slice of T
into a single value Self::Output
, placing a
given separator between each.
§Examples
assert_eq!(["hello", "world"].join(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]);
assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);
1.0.0 · sourcepub fn connect<Separator>(
&self,
sep: Separator,
) -> <[T] as Join<Separator>>::Output
👎Deprecated since 1.3.0: renamed to join
pub fn connect<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output
Flattens a slice of T
into a single value Self::Output
, placing a
given separator between each.
§Examples
assert_eq!(["hello", "world"].connect(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);
Trait Implementations§
source§impl<A: Array> BorrowMut<[<A as Array>::Item]> for ArrayVec<A>
impl<A: Array> BorrowMut<[<A as Array>::Item]> for ArrayVec<A>
source§fn borrow_mut(&mut self) -> &mut [A::Item]
fn borrow_mut(&mut self) -> &mut [A::Item]
source§impl<A: Array> Extend<<A as Array>::Item> for ArrayVec<A>
impl<A: Array> Extend<<A as Array>::Item> for ArrayVec<A>
source§fn extend<T: IntoIterator<Item = A::Item>>(&mut self, iter: T)
fn extend<T: IntoIterator<Item = A::Item>>(&mut self, iter: T)
source§fn extend_one(&mut self, item: A)
fn extend_one(&mut self, item: A)
extend_one
)source§fn extend_reserve(&mut self, additional: usize)
fn extend_reserve(&mut self, additional: usize)
extend_one
)source§impl<A: Array> From<A> for ArrayVec<A>
impl<A: Array> From<A> for ArrayVec<A>
source§fn from(data: A) -> Self
fn from(data: A) -> Self
The output has a length equal to the full array.
If you want to select a length, use
from_array_len
source§impl<'a, A: Array> IntoIterator for &'a ArrayVec<A>
impl<'a, A: Array> IntoIterator for &'a ArrayVec<A>
source§impl<'a, A: Array> IntoIterator for &'a mut ArrayVec<A>
impl<'a, A: Array> IntoIterator for &'a mut ArrayVec<A>
source§impl<A: Array> IntoIterator for ArrayVec<A>
impl<A: Array> IntoIterator for ArrayVec<A>
source§impl<A: Array> Ord for ArrayVec<A>
impl<A: Array> Ord for ArrayVec<A>
source§impl<A: Array> PartialEq<&[<A as Array>::Item]> for ArrayVec<A>
impl<A: Array> PartialEq<&[<A as Array>::Item]> for ArrayVec<A>
source§impl<A: Array> PartialEq for ArrayVec<A>
impl<A: Array> PartialEq for ArrayVec<A>
source§impl<A: Array> PartialOrd for ArrayVec<A>where
A::Item: PartialOrd,
impl<A: Array> PartialOrd for ArrayVec<A>where
A::Item: PartialOrd,
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read moreimpl<A> Copy for ArrayVec<A>
impl<A: Array> Eq for ArrayVec<A>
Auto Trait Implementations§
impl<A> Freeze for ArrayVec<A>where
A: Freeze,
impl<A> RefUnwindSafe for ArrayVec<A>where
A: RefUnwindSafe,
impl<A> Send for ArrayVec<A>where
A: Send,
impl<A> Sync for ArrayVec<A>where
A: Sync,
impl<A> Unpin for ArrayVec<A>where
A: Unpin,
impl<A> UnwindSafe for ArrayVec<A>where
A: UnwindSafe,
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§default unsafe fn clone_to_uninit(&self, dst: *mut T)
default unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)source§impl<T> CloneToUninit for Twhere
T: Copy,
impl<T> CloneToUninit for Twhere
T: Copy,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)