Struct rant::RequiredVarArgs
source · [−]pub struct RequiredVarArgs<T: TryFromRant>(_);
Expand description
Semantic wrapper around a Vec<T>
.
Use this type to add a required variadic (+
) parameter to native functions.
Implementations
sourceimpl<T: TryFromRant> RequiredVarArgs<T>
impl<T: TryFromRant> RequiredVarArgs<T>
Methods from Deref<Target = Vec<T>>
1.0.0 · sourcepub fn capacity(&self) -> usize
pub fn capacity(&self) -> usize
Returns the number of elements the vector can hold without reallocating.
Examples
let vec: Vec<i32> = Vec::with_capacity(10);
assert_eq!(vec.capacity(), 10);
1.0.0 · sourcepub fn reserve(&mut self, additional: usize)
pub fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional
more elements to be inserted
in the given Vec<T>
. The collection may reserve more space to avoid
frequent reallocations. After calling reserve
, capacity will be
greater than or equal to self.len() + additional
. Does nothing if
capacity is already sufficient.
Panics
Panics if the new capacity exceeds isize::MAX
bytes.
Examples
let mut vec = vec![1];
vec.reserve(10);
assert!(vec.capacity() >= 11);
1.0.0 · sourcepub fn reserve_exact(&mut self, additional: usize)
pub fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional
more elements to
be inserted in the given Vec<T>
. After calling reserve_exact
,
capacity will be greater than or equal to self.len() + additional
.
Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore, capacity can not be relied upon to be precisely
minimal. Prefer reserve
if future insertions are expected.
Panics
Panics if the new capacity exceeds isize::MAX
bytes.
Examples
let mut vec = vec![1];
vec.reserve_exact(10);
assert!(vec.capacity() >= 11);
1.57.0 · sourcepub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
Tries to reserve capacity for at least additional
more elements to be inserted
in the given Vec<T>
. The collection may reserve more space to avoid
frequent reallocations. After calling try_reserve
, capacity will be
greater than or equal to self.len() + additional
. Does nothing if
capacity is already sufficient.
Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
Examples
use std::collections::TryReserveError;
fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
let mut output = Vec::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.extend(data.iter().map(|&val| {
val * 2 + 5 // very complicated
}));
Ok(output)
}
1.57.0 · sourcepub fn try_reserve_exact(
&mut self,
additional: usize
) -> Result<(), TryReserveError>
pub fn try_reserve_exact(
&mut self,
additional: usize
) -> Result<(), TryReserveError>
Tries to reserve the minimum capacity for exactly additional
elements to be inserted in the given Vec<T>
. After calling
try_reserve_exact
, capacity will be greater than or equal to
self.len() + additional
if it returns Ok(())
.
Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore, capacity can not be relied upon to be precisely
minimal. Prefer try_reserve
if future insertions are expected.
Errors
If the capacity overflows, or the allocator reports a failure, then an error is returned.
Examples
use std::collections::TryReserveError;
fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
let mut output = Vec::new();
// Pre-reserve the memory, exiting if we can't
output.try_reserve_exact(data.len())?;
// Now we know this can't OOM in the middle of our complex work
output.extend(data.iter().map(|&val| {
val * 2 + 5 // very complicated
}));
Ok(output)
}
1.0.0 · sourcepub fn shrink_to_fit(&mut self)
pub fn shrink_to_fit(&mut self)
Shrinks the capacity of the vector as much as possible.
It will drop down as close as possible to the length but the allocator may still inform the vector that there is space for a few more elements.
Examples
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(vec.capacity(), 10);
vec.shrink_to_fit();
assert!(vec.capacity() >= 3);
1.56.0 · sourcepub fn shrink_to(&mut self, min_capacity: usize)
pub fn shrink_to(&mut self, min_capacity: usize)
Shrinks the capacity of the vector with a lower bound.
The capacity will remain at least as large as both the length and the supplied value.
If the current capacity is less than the lower limit, this is a no-op.
Examples
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(vec.capacity(), 10);
vec.shrink_to(4);
assert!(vec.capacity() >= 4);
vec.shrink_to(0);
assert!(vec.capacity() >= 3);
1.0.0 · sourcepub fn truncate(&mut self, len: usize)
pub fn truncate(&mut self, len: usize)
Shortens the vector, keeping the first len
elements and dropping
the rest.
If len
is greater than the vector’s current length, this has no
effect.
The drain
method can emulate truncate
, but causes the excess
elements to be returned instead of dropped.
Note that this method has no effect on the allocated capacity of the vector.
Examples
Truncating a five element vector to two elements:
let mut vec = vec![1, 2, 3, 4, 5];
vec.truncate(2);
assert_eq!(vec, [1, 2]);
No truncation occurs when len
is greater than the vector’s current
length:
let mut vec = vec![1, 2, 3];
vec.truncate(8);
assert_eq!(vec, [1, 2, 3]);
Truncating when len == 0
is equivalent to calling the clear
method.
let mut vec = vec![1, 2, 3];
vec.truncate(0);
assert_eq!(vec, []);
1.7.0 · sourcepub fn as_slice(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
pub fn as_slice(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
Extracts a slice containing the entire vector.
Equivalent to &s[..]
.
Examples
use std::io::{self, Write};
let buffer = vec![1, 2, 3, 5, 8];
io::sink().write(buffer.as_slice()).unwrap();
1.7.0 · sourcepub fn as_mut_slice(&mut self) -> &mut [T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
pub fn as_mut_slice(&mut self) -> &mut [T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
Extracts a mutable slice of the entire vector.
Equivalent to &mut s[..]
.
Examples
use std::io::{self, Read};
let mut buffer = vec![0; 3];
io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
1.37.0 · sourcepub fn as_ptr(&self) -> *const T
pub fn as_ptr(&self) -> *const T
Returns a raw pointer to the vector’s buffer.
The caller must ensure that the vector outlives the pointer this function returns, or else it will end up pointing to garbage. Modifying the vector may cause its buffer to be reallocated, which would also make any pointers to it invalid.
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
.
Examples
let x = vec![1, 2, 4];
let x_ptr = x.as_ptr();
unsafe {
for i in 0..x.len() {
assert_eq!(*x_ptr.add(i), 1 << i);
}
}
1.37.0 · 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 vector’s buffer.
The caller must ensure that the vector outlives the pointer this function returns, or else it will end up pointing to garbage. Modifying the vector may cause its buffer to be reallocated, which would also make any pointers to it invalid.
Examples
// Allocate vector big enough for 4 elements.
let size = 4;
let mut x: Vec<i32> = Vec::with_capacity(size);
let x_ptr = x.as_mut_ptr();
// Initialize elements via raw pointer writes, then set length.
unsafe {
for i in 0..size {
*x_ptr.add(i) = i as i32;
}
x.set_len(size);
}
assert_eq!(&*x, &[0, 1, 2, 3]);
sourcepub fn allocator(&self) -> &A
🔬 This is a nightly-only experimental API. (allocator_api
)
pub fn allocator(&self) -> &A
allocator_api
)Returns a reference to the underlying allocator.
1.0.0 · sourcepub unsafe fn set_len(&mut self, new_len: usize)
pub unsafe fn set_len(&mut self, new_len: usize)
Forces the length of the vector to new_len
.
This is a low-level operation that maintains none of the normal
invariants of the type. Normally changing the length of a vector
is done using one of the safe operations instead, such as
truncate
, resize
, extend
, or clear
.
Safety
new_len
must be less than or equal tocapacity()
.- The elements at
old_len..new_len
must be initialized.
Examples
This method can be useful for situations in which the vector is serving as a buffer for other code, particularly over FFI:
pub fn get_dictionary(&self) -> Option<Vec<u8>> {
// Per the FFI method's docs, "32768 bytes is always enough".
let mut dict = Vec::with_capacity(32_768);
let mut dict_length = 0;
// SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that:
// 1. `dict_length` elements were initialized.
// 2. `dict_length` <= the capacity (32_768)
// which makes `set_len` safe to call.
unsafe {
// Make the FFI call...
let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length);
if r == Z_OK {
// ...and update the length to what was initialized.
dict.set_len(dict_length);
Some(dict)
} else {
None
}
}
}
While the following example is sound, there is a memory leak since
the inner vectors were not freed prior to the set_len
call:
let mut vec = vec![vec![1, 0, 0],
vec![0, 1, 0],
vec![0, 0, 1]];
// SAFETY:
// 1. `old_len..0` is empty so no elements need to be initialized.
// 2. `0 <= capacity` always holds whatever `capacity` is.
unsafe {
vec.set_len(0);
}
Normally, here, one would use clear
instead to correctly drop
the contents and thus not leak memory.
1.0.0 · sourcepub fn swap_remove(&mut self, index: usize) -> T
pub fn swap_remove(&mut self, index: usize) -> T
Removes an element from the vector and returns it.
The removed element is replaced by the last element of the vector.
This does not preserve ordering, but is O(1).
If you need to preserve the element order, use remove
instead.
Panics
Panics if index
is out of bounds.
Examples
let mut v = vec!["foo", "bar", "baz", "qux"];
assert_eq!(v.swap_remove(1), "bar");
assert_eq!(v, ["foo", "qux", "baz"]);
assert_eq!(v.swap_remove(0), "foo");
assert_eq!(v, ["baz", "qux"]);
1.0.0 · sourcepub fn remove(&mut self, index: usize) -> T
pub fn remove(&mut self, index: usize) -> T
Removes and returns the element at position index
within the vector,
shifting all elements after it to the left.
Note: Because this shifts over the remaining elements, it has a
worst-case performance of O(n). If you don’t need the order of elements
to be preserved, use swap_remove
instead. If you’d like to remove
elements from the beginning of the Vec
, consider using
VecDeque::pop_front
instead.
Panics
Panics if index
is out of bounds.
Examples
let mut v = vec![1, 2, 3];
assert_eq!(v.remove(1), 2);
assert_eq!(v, [1, 3]);
1.0.0 · sourcepub fn retain<F>(&mut self, f: F) where
F: FnMut(&T) -> bool,
pub fn retain<F>(&mut self, f: F) where
F: FnMut(&T) -> bool,
Retains only the elements specified by the predicate.
In other words, remove all elements e
for which f(&e)
returns false
.
This method operates in place, visiting each element exactly once in the
original order, and preserves the order of the retained elements.
Examples
let mut vec = vec![1, 2, 3, 4];
vec.retain(|&x| x % 2 == 0);
assert_eq!(vec, [2, 4]);
Because the elements are visited exactly once in the original order, external state may be used to decide which elements to keep.
let mut vec = vec![1, 2, 3, 4, 5];
let keep = [false, true, true, false, true];
let mut iter = keep.iter();
vec.retain(|_| *iter.next().unwrap());
assert_eq!(vec, [2, 3, 5]);
1.61.0 · sourcepub fn retain_mut<F>(&mut self, f: F) where
F: FnMut(&mut T) -> bool,
pub fn retain_mut<F>(&mut self, f: F) where
F: FnMut(&mut T) -> bool,
Retains only the elements specified by the predicate, passing a mutable reference to it.
In other words, remove all elements e
such that f(&mut e)
returns false
.
This method operates in place, visiting each element exactly once in the
original order, and preserves the order of the retained elements.
Examples
let mut vec = vec![1, 2, 3, 4];
vec.retain_mut(|x| if *x > 3 {
false
} else {
*x += 1;
true
});
assert_eq!(vec, [2, 3, 4]);
1.16.0 · sourcepub fn dedup_by_key<F, K>(&mut self, key: F) where
F: FnMut(&mut T) -> K,
K: PartialEq<K>,
pub fn dedup_by_key<F, K>(&mut self, key: F) where
F: FnMut(&mut T) -> K,
K: PartialEq<K>,
Removes all but the first of consecutive elements in the vector that resolve to the same key.
If the vector is sorted, this removes all duplicates.
Examples
let mut vec = vec![10, 20, 21, 30, 20];
vec.dedup_by_key(|i| *i / 10);
assert_eq!(vec, [10, 20, 30, 20]);
1.16.0 · sourcepub fn dedup_by<F>(&mut self, same_bucket: F) where
F: FnMut(&mut T, &mut T) -> bool,
pub fn dedup_by<F>(&mut self, same_bucket: F) where
F: FnMut(&mut T, &mut T) -> bool,
Removes all but the first of consecutive elements in the vector satisfying a given equality relation.
The same_bucket
function is passed references to two elements from the vector 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 removed.
If the vector is sorted, this removes all duplicates.
Examples
let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
1.0.0 · sourcepub fn pop(&mut self) -> Option<T>
pub fn pop(&mut self) -> Option<T>
Removes the last element from a vector and returns it, or None
if it
is empty.
If you’d like to pop the first element, consider using
VecDeque::pop_front
instead.
Examples
let mut vec = vec![1, 2, 3];
assert_eq!(vec.pop(), Some(3));
assert_eq!(vec, [1, 2]);
1.6.0 · sourcepub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A> where
R: RangeBounds<usize>,
pub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A> where
R: RangeBounds<usize>,
Removes the specified range from the vector in bulk, returning all removed elements as an iterator. If the iterator is dropped before being fully consumed, it drops the remaining removed elements.
The returned iterator keeps a mutable borrow on the vector to optimize its implementation.
Panics
Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.
Leaking
If the returned iterator goes out of scope without being dropped (due to
mem::forget
, for example), the vector may have lost and leaked
elements arbitrarily, including elements outside the range.
Examples
let mut v = vec![1, 2, 3];
let u: Vec<_> = v.drain(1..).collect();
assert_eq!(v, &[1]);
assert_eq!(u, &[2, 3]);
// A full range clears the vector, like `clear()` does
v.drain(..);
assert_eq!(v, &[]);
1.0.0 · sourcepub fn clear(&mut self)
pub fn clear(&mut self)
Clears the vector, removing all values.
Note that this method has no effect on the allocated capacity of the vector.
Examples
let mut v = vec![1, 2, 3];
v.clear();
assert!(v.is_empty());
1.0.0 · sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the number of elements in the vector, also referred to as its ‘length’.
Examples
let a = vec![1, 2, 3];
assert_eq!(a.len(), 3);
1.0.0 · sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true
if the vector contains no elements.
Examples
let mut v = Vec::new();
assert!(v.is_empty());
v.push(1);
assert!(!v.is_empty());
1.4.0 · sourcepub fn split_off(&mut self, at: usize) -> Vec<T, A>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
A: Clone,
pub fn split_off(&mut self, at: usize) -> Vec<T, A>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
A: Clone,
A: Allocator,
Splits the collection into two at the given index.
Returns a newly allocated vector containing the elements in the range
[at, len)
. After the call, the original vector will be left containing
the elements [0, at)
with its previous capacity unchanged.
Panics
Panics if at > len
.
Examples
let mut vec = vec![1, 2, 3];
let vec2 = vec.split_off(1);
assert_eq!(vec, [1]);
assert_eq!(vec2, [2, 3]);
1.33.0 · sourcepub fn resize_with<F>(&mut self, new_len: usize, f: F) where
F: FnMut() -> T,
pub fn resize_with<F>(&mut self, new_len: usize, f: F) where
F: FnMut() -> T,
Resizes the Vec
in-place so that len
is equal to new_len
.
If new_len
is greater than len
, the Vec
is extended by the
difference, with each additional slot filled with the result of
calling the closure f
. The return values from f
will end up
in the Vec
in the order they have been generated.
If new_len
is less than len
, the Vec
is simply truncated.
This method uses a closure to create new values on every push. If
you’d rather Clone
a given value, use Vec::resize
. If you
want to use the Default
trait to generate values, you can
pass Default::default
as the second argument.
Examples
let mut vec = vec![1, 2, 3];
vec.resize_with(5, Default::default);
assert_eq!(vec, [1, 2, 3, 0, 0]);
let mut vec = vec![];
let mut p = 1;
vec.resize_with(4, || { p *= 2; p });
assert_eq!(vec, [2, 4, 8, 16]);
1.60.0 · sourcepub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>]
pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>]
Returns the remaining spare capacity of the vector as a slice of
MaybeUninit<T>
.
The returned slice can be used to fill the vector with data (e.g. by
reading from a file) before marking the data as initialized using the
set_len
method.
Examples
// Allocate vector big enough for 10 elements.
let mut v = Vec::with_capacity(10);
// Fill in the first 3 elements.
let uninit = v.spare_capacity_mut();
uninit[0].write(0);
uninit[1].write(1);
uninit[2].write(2);
// Mark the first 3 elements of the vector as being initialized.
unsafe {
v.set_len(3);
}
assert_eq!(&v, &[0, 1, 2]);
sourcepub fn split_at_spare_mut(&mut self) -> (&mut [T], &mut [MaybeUninit<T>])
🔬 This is a nightly-only experimental API. (vec_split_at_spare
)
pub fn split_at_spare_mut(&mut self) -> (&mut [T], &mut [MaybeUninit<T>])
vec_split_at_spare
)Returns vector content as a slice of T
, along with the remaining spare
capacity of the vector as a slice of MaybeUninit<T>
.
The returned spare capacity slice can be used to fill the vector with data
(e.g. by reading from a file) before marking the data as initialized using
the set_len
method.
Note that this is a low-level API, which should be used with care for
optimization purposes. If you need to append data to a Vec
you can use push
, extend
, extend_from_slice
,
extend_from_within
, insert
, append
, resize
or
resize_with
, depending on your exact needs.
Examples
#![feature(vec_split_at_spare)]
let mut v = vec![1, 1, 2];
// Reserve additional space big enough for 10 elements.
v.reserve(10);
let (init, uninit) = v.split_at_spare_mut();
let sum = init.iter().copied().sum::<u32>();
// Fill in the next 4 elements.
uninit[0].write(sum);
uninit[1].write(sum * 2);
uninit[2].write(sum * 3);
uninit[3].write(sum * 4);
// Mark the 4 elements of the vector as being initialized.
unsafe {
let len = v.len();
v.set_len(len + 4);
}
assert_eq!(&v, &[1, 1, 2, 4, 8, 12, 16]);
1.5.0 · sourcepub fn resize(&mut self, new_len: usize, value: T)
pub fn resize(&mut self, new_len: usize, value: T)
Resizes the Vec
in-place so that len
is equal to new_len
.
If new_len
is greater than len
, the Vec
is extended by the
difference, with each additional slot filled with value
.
If new_len
is less than len
, the Vec
is simply truncated.
This method requires T
to implement Clone
,
in order to be able to clone the passed value.
If you need more flexibility (or want to rely on Default
instead of
Clone
), use Vec::resize_with
.
If you only need to resize to a smaller size, use Vec::truncate
.
Examples
let mut vec = vec!["hello"];
vec.resize(3, "world");
assert_eq!(vec, ["hello", "world", "world"]);
let mut vec = vec![1, 2, 3, 4];
vec.resize(2, 0);
assert_eq!(vec, [1, 2]);
1.6.0 · sourcepub fn extend_from_slice(&mut self, other: &[T])
pub fn extend_from_slice(&mut self, other: &[T])
Clones and appends all elements in a slice to the Vec
.
Iterates over the slice other
, clones each element, and then appends
it to this Vec
. The other
slice is traversed in-order.
Note that this function is same as extend
except that it is
specialized to work with slices instead. If and when Rust gets
specialization this function will likely be deprecated (but still
available).
Examples
let mut vec = vec![1];
vec.extend_from_slice(&[2, 3, 4]);
assert_eq!(vec, [1, 2, 3, 4]);
1.53.0 · sourcepub fn extend_from_within<R>(&mut self, src: R) where
R: RangeBounds<usize>,
pub fn extend_from_within<R>(&mut self, src: R) where
R: RangeBounds<usize>,
Copies elements from src
range to the end of the vector.
Panics
Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.
Examples
let mut vec = vec![0, 1, 2, 3, 4];
vec.extend_from_within(2..);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4]);
vec.extend_from_within(..2);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1]);
vec.extend_from_within(4..8);
assert_eq!(vec, [0, 1, 2, 3, 4, 2, 3, 4, 0, 1, 4, 2, 3, 4]);
1.21.0 · sourcepub fn splice<R, I>(
&mut self,
range: R,
replace_with: I
) -> Splice<'_, <I as IntoIterator>::IntoIter, A> where
R: RangeBounds<usize>,
I: IntoIterator<Item = T>,
pub fn splice<R, I>(
&mut self,
range: R,
replace_with: I
) -> Splice<'_, <I as IntoIterator>::IntoIter, A> where
R: RangeBounds<usize>,
I: IntoIterator<Item = T>,
Creates a splicing iterator that replaces the specified range in the vector
with the given replace_with
iterator and yields the removed items.
replace_with
does not need to be the same length as range
.
range
is removed even if the iterator is not consumed until the end.
It is unspecified how many elements are removed from the vector
if the Splice
value is leaked.
The input iterator replace_with
is only consumed when the Splice
value is dropped.
This is optimal if:
- The tail (elements in the vector after
range
) is empty, - or
replace_with
yields fewer or equal elements thanrange
’s length - or the lower bound of its
size_hint()
is exact.
Otherwise, a temporary vector is allocated and the tail is moved twice.
Panics
Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.
Examples
let mut v = vec![1, 2, 3, 4];
let new = [7, 8, 9];
let u: Vec<_> = v.splice(1..3, new).collect();
assert_eq!(v, &[1, 7, 8, 9, 4]);
assert_eq!(u, &[2, 3]);
sourcepub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F, A> where
F: FnMut(&mut T) -> bool,
🔬 This is a nightly-only experimental API. (drain_filter
)
pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F, A> where
F: FnMut(&mut T) -> bool,
drain_filter
)Creates an iterator which uses a closure to determine if an element should be removed.
If the closure returns true, then the element is removed and yielded. If the closure returns false, the element will remain in the vector and will not be yielded by the iterator.
Using this method is equivalent to the following code:
let mut i = 0;
while i < vec.len() {
if some_predicate(&mut vec[i]) {
let val = vec.remove(i);
// your code here
} else {
i += 1;
}
}
But drain_filter
is easier to use. drain_filter
is also more efficient,
because it can backshift the elements of the array in bulk.
Note that drain_filter
also lets you mutate every element in the filter closure,
regardless of whether you choose to keep or remove it.
Examples
Splitting an array into evens and odds, reusing the original allocation:
#![feature(drain_filter)]
let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<Vec<_>>();
let odds = numbers;
assert_eq!(evens, vec![2, 4, 6, 8, 14]);
assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]);
Methods from Deref<Target = [T]>
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.
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");
sourcepub fn trim_ascii_start(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii_start(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
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"");
sourcepub fn trim_ascii_end(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii_end(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
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"");
sourcepub fn trim_ascii(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with leading and trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
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 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]);
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 pointer to the last item in the slice.
Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_mut() {
*last = 10;
}
assert_eq!(x, &[0, 1, 10]);
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]>>::Output where
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Output where
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.
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]>>::Output where
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I
) -> &mut <I as SliceIndex<[T]>>::Output where
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.
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++.
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.
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.
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 = ['r', 'u', 's', 't'];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), &['r', 'u']);
assert_eq!(iter.next().unwrap(), &['u', 's']);
assert_eq!(iter.next().unwrap(), &['s', 't']);
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());
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']);
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 chunks
.
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]);
sourcepub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
F: FnMut(&T, &T) -> bool,
🔬 This is a nightly-only experimental API. (slice_group_by
)
pub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
F: FnMut(&T, &T) -> bool,
slice_group_by
)Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.
The predicate is called on two elements following themselves,
it means the predicate is called on slice[0]
and slice[1]
then on slice[1]
and slice[2]
and so on.
Examples
#![feature(slice_group_by)]
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.group_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:
#![feature(slice_group_by)]
let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.group_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);
sourcepub fn group_by_mut<F>(&mut self, pred: F) -> GroupByMut<'_, T, F> where
F: FnMut(&T, &T) -> bool,
🔬 This is a nightly-only experimental API. (slice_group_by
)
pub fn group_by_mut<F>(&mut self, pred: F) -> GroupByMut<'_, T, F> where
F: FnMut(&T, &T) -> bool,
slice_group_by
)Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.
The predicate is called on two elements following themselves,
it means the predicate is called on slice[0]
and slice[1]
then on slice[1]
and slice[2]
and so on.
Examples
#![feature(slice_group_by)]
let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.group_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:
#![feature(slice_group_by)]
let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.group_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
.
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
.
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]);
sourcepub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
🔬 This is a nightly-only experimental API. (slice_split_at_unchecked
)
pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
slice_split_at_unchecked
)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
#![feature(slice_split_at_unchecked)]
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, []);
}
sourcepub unsafe fn split_at_mut_unchecked(
&mut self,
mid: usize
) -> (&mut [T], &mut [T])
🔬 This is a nightly-only experimental API. (slice_split_at_unchecked
)
pub unsafe fn split_at_mut_unchecked(
&mut self,
mid: usize
) -> (&mut [T], &mut [T])
slice_split_at_unchecked
)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
#![feature(slice_split_at_unchecked)]
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]);
sourcepub fn split_array_ref<const N: usize>(&self) -> (&[T; N], &[T])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn split_array_ref<const N: usize>(&self) -> (&[T; N], &[T])
split_array
)Divides one slice into an array and a remainder slice at an index.
The array will contain all indices from [0, N)
(excluding
the index N
itself) and the slice will contain all
indices from [N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
{
let (left, right) = v.split_array_ref::<0>();
assert_eq!(left, &[]);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
{
let (left, right) = v.split_array_ref::<2>();
assert_eq!(left, &[1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
{
let (left, right) = v.split_array_ref::<6>();
assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
sourcepub fn split_array_mut<const N: usize>(&mut self) -> (&mut [T; N], &mut [T])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn split_array_mut<const N: usize>(&mut self) -> (&mut [T; N], &mut [T])
split_array
)Divides one mutable slice into an array and a remainder slice at an index.
The array will contain all indices from [0, N)
(excluding
the index N
itself) and the slice will contain all
indices from [N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let mut v = &mut [1, 0, 3, 0, 5, 6][..];
let (left, right) = v.split_array_mut::<2>();
assert_eq!(left, &mut [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
sourcepub fn rsplit_array_ref<const N: usize>(&self) -> (&[T], &[T; N])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn rsplit_array_ref<const N: usize>(&self) -> (&[T], &[T; N])
split_array
)Divides one slice into an array and a remainder slice at an index from the end.
The slice will contain all indices from [0, len - N)
(excluding
the index len - N
itself) and the array will contain all
indices from [len - N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
{
let (left, right) = v.rsplit_array_ref::<0>();
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, &[]);
}
{
let (left, right) = v.rsplit_array_ref::<2>();
assert_eq!(left, [1, 2, 3, 4]);
assert_eq!(right, &[5, 6]);
}
{
let (left, right) = v.rsplit_array_ref::<6>();
assert_eq!(left, []);
assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}
sourcepub fn rsplit_array_mut<const N: usize>(&mut self) -> (&mut [T], &mut [T; N])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn rsplit_array_mut<const N: usize>(&mut self) -> (&mut [T], &mut [T; N])
split_array
)Divides one mutable slice into an array and a remainder slice at an index from the end.
The slice will contain all indices from [0, len - N)
(excluding
the index N
itself) and the array will contain all
indices from [len - N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let mut v = &mut [1, 0, 3, 0, 5, 6][..];
let (left, right) = v.rsplit_array_mut::<4>();
assert_eq!(left, [1, 0]);
assert_eq!(right, &mut [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
1.0.0 · sourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F> where
F: FnMut(&T) -> bool,
pub fn split<F>(&self, pred: F) -> Split<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F> where
F: FnMut(&T) -> bool,
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
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> where
F: FnMut(&T) -> bool,
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> where
F: FnMut(&T) -> bool,
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> where
F: FnMut(&T) -> bool,
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F> where
F: FnMut(&T) -> bool,
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]);
1.0.0 · sourcepub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
pub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
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]) -> bool where
T: PartialEq<T>,
pub fn starts_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
Returns true
if needle
is a prefix of the slice.
Examples
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
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]) -> bool where
T: PartialEq<T>,
pub fn ends_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
Returns true
if needle
is a suffix of the slice.
Examples
let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
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]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<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 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(&[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]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<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 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(&[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.
This behaves similary to contains
if this slice is sorted.
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 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);
// The above is equivalent to `let idx = s.binary_search(&num).unwrap_or_else(|x| x);`
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> where
F: FnMut(&'a T) -> Ordering,
pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize> where
F: FnMut(&'a T) -> Ordering,
Binary searches this slice with a comparator function.
This behaves similarly to contains
if this slice is sorted.
The comparator function should implement an order consistent
with the sort order of the underlying slice, returning an
order code that indicates whether its argument is Less
,
Equal
or Greater
the desired target.
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> where
F: FnMut(&'a T) -> B,
B: Ord,
pub fn binary_search_by_key<'a, B, F>(
&'a self,
b: &B,
f: F
) -> Result<usize, usize> where
F: FnMut(&'a T) -> B,
B: Ord,
Binary searches this slice with a key extraction function.
This behaves similarly to contains
if this slice is sorted.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
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, but might not preserve the 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.
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
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) where
F: FnMut(&T, &T) -> Ordering,
pub fn sort_unstable_by<F>(&mut self, compare: F) where
F: FnMut(&T, &T) -> Ordering,
Sorts the slice with a comparator function, but might not preserve the 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 must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (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 algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
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) where
F: FnMut(&T) -> K,
K: Ord,
pub fn sort_unstable_by_key<K, F>(&mut self, f: F) where
F: FnMut(&T) -> K,
K: Ord,
Sorts the slice with a key extraction function, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(m * n * log(n)) worst-case, where the key function is O(m).
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
Due to its key calling strategy, sort_unstable_by_key
is likely to be slower than sort_by_cached_key
in
cases where the key function is expensive.
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
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 O(n) worst-case. This function is also/ known as “kth
element” in other libraries. It returns a triplet of the following values: all elements less
than the one at the given index, the value at the given index, and all elements greater than
the one at the given index.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median
v.select_nth_unstable(2);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
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]) where
F: FnMut(&T, &T) -> Ordering,
pub fn select_nth_unstable_by<F>(
&mut self,
index: usize,
compare: F
) -> (&mut [T], &mut T, &mut [T]) where
F: FnMut(&T, &T) -> Ordering,
Reorder the slice with a comparator function such that the element at index
is at its
final sorted position.
This reordering has the additional property that any value at position i < index
will be
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 O(n) worst-case. This function
is also known as “kth element” in other libraries. It returns a triplet of the following
values: all elements less than the one at the given index, the value at the given index,
and all elements greater than the one at the given index, using the provided comparator
function.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median as if the slice were sorted in descending order.
v.select_nth_unstable_by(2, |a, b| b.cmp(a));
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
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]) where
F: FnMut(&T) -> K,
K: Ord,
pub fn select_nth_unstable_by_key<K, F>(
&mut self,
index: usize,
f: F
) -> (&mut [T], &mut T, &mut [T]) where
F: FnMut(&T) -> K,
K: Ord,
Reorder the slice with a key extraction function such that the element at index
is at its
final sorted position.
This reordering has the additional property that any value at position i < index
will be
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 O(n) worst-case. This function
is also known as “kth element” in other libraries. It returns a triplet of the following
values: all elements less than the one at the given index, the value at the given index, and
all elements greater than the one at the given index, using the provided key extraction
function.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm
used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Return the median as if the array were sorted according to absolute value.
v.select_nth_unstable_by_key(2, |a| a.abs());
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
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<T>,
🔬 This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T]) where
T: PartialEq<T>,
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]) where
F: FnMut(&mut T, &mut T) -> bool,
🔬 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]) where
F: FnMut(&mut T, &mut T) -> bool,
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]) where
F: FnMut(&mut T) -> K,
K: PartialEq<K>,
🔬 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]) where
F: FnMut(&mut T) -> K,
K: PartialEq<K>,
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']);
Rotate 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) where
R: RangeBounds<usize>,
T: Copy,
pub fn copy_within<R>(&mut self, src: R, dest: usize) where
R: RangeBounds<usize>,
T: Copy,
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 method may make the middle slice the greatest length possible for a given type and input slice, but only your algorithm’s performance should depend on that, not its correctness. It is permissible for all of the input data to be returned as the prefix or suffix slice.
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 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 method may make the middle slice the greatest length possible for a given type and input slice, but only your algorithm’s performance should depend on that, not its correctness. It is permissible for all of the input data to be returned as the prefix or suffix slice.
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]) where
T: SimdElement,
Simd<T, LANES>: AsRef<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
🔬 This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T]) where
T: SimdElement,
Simd<T, LANES>: AsRef<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
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)]
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;
use std::simd::f32x4;
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]) where
T: SimdElement,
Simd<T, LANES>: AsMut<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
🔬 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]) where
T: SimdElement,
Simd<T, LANES>: AsMut<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
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_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) -> bool where
T: PartialOrd<T>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted(&self) -> bool where
T: PartialOrd<T>,
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<F>(&self, compare: F) -> bool where
F: FnMut(&T, &T) -> Option<Ordering>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by<F>(&self, compare: F) -> bool where
F: FnMut(&T, &T) -> Option<Ordering>,
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 the ordering of two elements. Apart from that, it’s equivalent to
is_sorted
; see its documentation for more information.
sourcepub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
F: FnMut(&T) -> K,
K: PartialOrd<K>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
F: FnMut(&T) -> K,
K: PartialOrd<K>,
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 where
P: FnMut(&T) -> bool,
pub fn partition_point<P>(&self, pred: P) -> usize where
P: FnMut(&T) -> bool,
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 a 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 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<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<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<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<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(self: &mut &'a [T]) -> Option<&'a T>
🔬 This is a nightly-only experimental API. (slice_take
)
pub fn take_first(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(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬 This is a nightly-only experimental API. (slice_take
)
pub fn take_first_mut(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(self: &mut &'a [T]) -> Option<&'a T>
🔬 This is a nightly-only experimental API. (slice_take
)
pub fn take_last(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(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬 This is a nightly-only experimental API. (slice_take
)
pub fn take_last_mut(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 fn flatten(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (slice_flatten
)
pub fn flatten(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
slice_flatten
)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
#![feature(slice_flatten)]
assert_eq!([[1, 2, 3], [4, 5, 6]].flatten(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].flatten(),
[[1, 2], [3, 4], [5, 6]].flatten(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.flatten().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.flatten().is_empty());
sourcepub fn flatten_mut(&mut self) -> &mut [T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (slice_flatten
)
pub fn flatten_mut(&mut self) -> &mut [T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
slice_flatten
)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
#![feature(slice_flatten)]
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.flatten_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> Vec<u8, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
pub fn to_ascii_uppercase(&self) -> Vec<u8, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
A: Allocator,
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, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
pub fn to_ascii_lowercase(&self) -> Vec<u8, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
A: Allocator,
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.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
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) where
F: FnMut(&T, &T) -> Ordering,
pub fn sort_by<F>(&mut self, compare: F) where
F: FnMut(&T, &T) -> Ordering,
Sorts the slice with a comparator function.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (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_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable_by
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
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) where
F: FnMut(&T) -> K,
K: Ord,
pub fn sort_by_key<K, F>(&mut self, f: F) where
F: FnMut(&T) -> K,
K: Ord,
Sorts the slice with a key extraction function.
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).
For expensive key functions (e.g. functions that are not simple property accesses or
basic operations), sort_by_cached_key
is likely to be
significantly faster, as it does not recompute element keys.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable_by_key
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
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) where
F: FnMut(&T) -> K,
K: Ord,
pub fn sort_by_cached_key<K, F>(&mut self, f: F) where
F: FnMut(&T) -> K,
K: Ord,
Sorts the slice with a key extraction function.
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.
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).
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 algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
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, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
T: Clone,
pub fn to_vec(&self) -> Vec<T, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
T: Clone,
A: Allocator,
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>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
A: Allocator,
T: Clone,
🔬 This is a nightly-only experimental API. (allocator_api
)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
A: Allocator,
T: Clone,
A: Allocator,
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.
1.40.0 · sourcepub fn repeat(&self, n: usize) -> Vec<T, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
T: Copy,
pub fn repeat(&self, n: usize) -> Vec<T, Global>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
where
T: Copy,
A: Allocator,
1.0.0 · sourcepub fn concat<Item>(&self) -> <[T] as Concat<Item>>::OutputⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
Item: ?Sized,
[T]: Concat<Item>,
pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::OutputⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
Item: ?Sized,
[T]: Concat<Item>,
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ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
[T]: Join<Separator>,
pub fn join<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::OutputⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
[T]: Join<Separator>,
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ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
[T]: Join<Separator>,
👎 Deprecated since 1.3.0: renamed to join
pub fn connect<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::OutputⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
[T]: Join<Separator>,
renamed to join
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
sourceimpl<T: TryFromRant> Deref for RequiredVarArgs<T>
impl<T: TryFromRant> Deref for RequiredVarArgs<T>
sourceimpl<T: TryFromRant> DerefMut for RequiredVarArgs<T>
impl<T: TryFromRant> DerefMut for RequiredVarArgs<T>
sourceimpl<VarArgItem: TryFromRant> FromRantArgs for RequiredVarArgs<VarArgItem>
impl<VarArgItem: TryFromRant> FromRantArgs for RequiredVarArgs<VarArgItem>
fn from_rant_args(args: Vec<RantValue>) -> ValueResult<Self>
fn as_rant_params() -> Vec<Parameter>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where
A: Allocator,
A: Allocator,
Auto Trait Implementations
impl<T> RefUnwindSafe for RequiredVarArgs<T> where
T: RefUnwindSafe,
impl<T> Send for RequiredVarArgs<T> where
T: Send,
impl<T> Sync for RequiredVarArgs<T> where
T: Sync,
impl<T> Unpin for RequiredVarArgs<T> where
T: Unpin,
impl<T> UnwindSafe for RequiredVarArgs<T> where
T: UnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more