Struct mz_repr::DatumVecBorrow
source · pub struct DatumVecBorrow<'outer> {
outer: &'outer mut Vec<Datum<'static>>,
inner: Vec<Datum<'outer>>,
}
Expand description
A borrowed allocation of Datum
with a specific lifetime.
When an instance is dropped, its allocation is returned to the vector from which it was extracted.
Fields§
§outer: &'outer mut Vec<Datum<'static>>
§inner: Vec<Datum<'outer>>
Methods from Deref<Target = Vec<Datum<'outer>>>§
1.0.0 · sourcepub fn capacity(&self) -> usize
pub fn capacity(&self) -> usize
Returns the total number of elements the vector can hold without reallocating.
§Examples
let mut vec: Vec<i32> = Vec::with_capacity(10);
vec.push(42);
assert!(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
speculatively 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 at least additional
more elements to
be inserted in the given Vec<T>
. Unlike reserve
, this will not
deliberately over-allocate to speculatively avoid frequent allocations.
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 speculatively avoid
frequent reallocations. After calling try_reserve
, capacity will be
greater than or equal to self.len() + additional
if it returns
Ok(())
. Does nothing if capacity is already sufficient. This method
preserves the contents even if an error occurs.
§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 at least additional
elements to be inserted in the given Vec<T>
. Unlike try_reserve
,
this will not deliberately over-allocate to speculatively avoid frequent
allocations. 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.
The behavior of this method depends on the allocator, which may either shrink the vector
in-place or reallocate. The resulting vector might still have some excess capacity, just as
is the case for with_capacity
. See Allocator::shrink
for more details.
§Examples
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert!(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!(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 or equal to 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]
pub fn as_slice(&self) -> &[T]
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]
pub fn as_mut_slice(&mut self) -> &mut [T]
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, or a dangling raw pointer valid for zero sized reads if the vector didn’t allocate.
The caller must ensure that the vector outlives the pointer this function returns, or else it will end up dangling. 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
.
This method guarantees that for the purpose of the aliasing model, this method
does not materialize a reference to the underlying slice, and thus the returned pointer
will remain valid when mixed with other calls to as_ptr
and as_mut_ptr
.
Note that calling other methods that materialize mutable references to the slice,
or mutable references to specific elements you are planning on accessing through this pointer,
as well as writing to those elements, may still invalidate this pointer.
See the second example below for how this guarantee can be used.
§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);
}
}
Due to the aliasing guarantee, the following code is legal:
unsafe {
let mut v = vec![0, 1, 2];
let ptr1 = v.as_ptr();
let _ = ptr1.read();
let ptr2 = v.as_mut_ptr().offset(2);
ptr2.write(2);
// Notably, the write to `ptr2` did *not* invalidate `ptr1`
// because it mutated a different element:
let _ = ptr1.read();
}
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, or a dangling raw pointer valid for zero sized reads if the vector didn’t allocate.
The caller must ensure that the vector outlives the pointer this function returns, or else it will end up dangling. Modifying the vector may cause its buffer to be reallocated, which would also make any pointers to it invalid.
This method guarantees that for the purpose of the aliasing model, this method
does not materialize a reference to the underlying slice, and thus the returned pointer
will remain valid when mixed with other calls to as_ptr
and as_mut_ptr
.
Note that calling other methods that materialize references to the slice,
or references to specific elements you are planning on accessing through this pointer,
may still invalidate this pointer.
See the second example below for how this guarantee can be used.
§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]);
Due to the aliasing guarantee, the following code is legal:
unsafe {
let mut v = vec![0];
let ptr1 = v.as_mut_ptr();
ptr1.write(1);
let ptr2 = v.as_mut_ptr();
ptr2.write(2);
// Notably, the write to `ptr2` did *not* invalidate `ptr1`:
ptr1.write(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 of the remaining elements, 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 insert(&mut self, index: usize, element: T)
pub fn insert(&mut self, index: usize, element: T)
Inserts an element at position index
within the vector, shifting all
elements after it to the right.
§Panics
Panics if index > len
.
§Examples
let mut vec = vec![1, 2, 3];
vec.insert(1, 4);
assert_eq!(vec, [1, 4, 2, 3]);
vec.insert(4, 5);
assert_eq!(vec, [1, 4, 2, 3, 5]);
§Time complexity
Takes O(Vec::len
) time. All items after the insertion index must be
shifted to the right. In the worst case, all elements are shifted when
the insertion index is 0.
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)
pub fn retain<F>(&mut self, f: F)
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)
pub fn retain_mut<F>(&mut self, f: F)
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 {
*x += 1;
true
} else {
false
});
assert_eq!(vec, [2, 3, 4]);
1.16.0 · sourcepub fn dedup_by_key<F, K>(&mut self, key: F)
pub fn dedup_by_key<F, K>(&mut self, key: F)
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)
pub fn dedup_by<F>(&mut self, same_bucket: F)
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 push(&mut self, value: T)
pub fn push(&mut self, value: T)
Appends an element to the back of a collection.
§Panics
Panics if the new capacity exceeds isize::MAX
bytes.
§Examples
let mut vec = vec![1, 2];
vec.push(3);
assert_eq!(vec, [1, 2, 3]);
§Time complexity
Takes amortized O(1) time. If the vector’s length would exceed its capacity after the push, O(capacity) time is taken to copy the vector’s elements to a larger allocation. This expensive operation is offset by the capacity O(1) insertions it allows.
sourcepub fn push_within_capacity(&mut self, value: T) -> Result<(), T>
🔬This is a nightly-only experimental API. (vec_push_within_capacity
)
pub fn push_within_capacity(&mut self, value: T) -> Result<(), T>
vec_push_within_capacity
)Appends an element if there is sufficient spare capacity, otherwise an error is returned with the element.
Unlike push
this method will not reallocate when there’s insufficient capacity.
The caller should use reserve
or try_reserve
to ensure that there is enough capacity.
§Examples
A manual, panic-free alternative to FromIterator
:
#![feature(vec_push_within_capacity)]
use std::collections::TryReserveError;
fn from_iter_fallible<T>(iter: impl Iterator<Item=T>) -> Result<Vec<T>, TryReserveError> {
let mut vec = Vec::new();
for value in iter {
if let Err(value) = vec.push_within_capacity(value) {
vec.try_reserve(1)?;
// this cannot fail, the previous line either returned or added at least 1 free slot
let _ = vec.push_within_capacity(value);
}
}
Ok(vec)
}
assert_eq!(from_iter_fallible(0..100), Ok(Vec::from_iter(0..100)));
§Time complexity
Takes O(1) time.
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]);
§Time complexity
Takes O(1) time.
sourcepub fn pop_if<F>(&mut self, f: F) -> Option<T>
🔬This is a nightly-only experimental API. (vec_pop_if
)
pub fn pop_if<F>(&mut self, f: F) -> Option<T>
vec_pop_if
)Removes and returns the last element in a vector if the predicate
returns true
, or None
if the predicate returns false or the vector
is empty.
§Examples
#![feature(vec_pop_if)]
let mut vec = vec![1, 2, 3, 4];
let pred = |x: &mut i32| *x % 2 == 0;
assert_eq!(vec.pop_if(pred), Some(4));
assert_eq!(vec, [1, 2, 3]);
assert_eq!(vec.pop_if(pred), None);
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>where
A: Clone,
pub fn split_off(&mut self, at: usize) -> Vec<T, A>where
A: Clone,
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.
- If you want to take ownership of the entire contents and capacity of
the vector, see
mem::take
ormem::replace
. - If you don’t need the returned vector at all, see
Vec::truncate
. - If you want to take ownership of an arbitrary subslice, or you don’t
necessarily want to store the removed items in a vector, see
Vec::drain
.
§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>
pub fn splice<R, I>( &mut self, range: R, replace_with: I, ) -> Splice<'_, <I as IntoIterator>::IntoIter, A>
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 extract_if<F>(&mut self, filter: F) -> ExtractIf<'_, T, F, A>
🔬This is a nightly-only experimental API. (extract_if
)
pub fn extract_if<F>(&mut self, filter: F) -> ExtractIf<'_, T, F, A>
extract_if
)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.
If the returned ExtractIf
is not exhausted, e.g. because it is dropped without iterating
or the iteration short-circuits, then the remaining elements will be retained.
Use retain
with a negated predicate if you do not need the returned 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 extract_if
is easier to use. extract_if
is also more efficient,
because it can backshift the elements of the array in bulk.
Note that extract_if
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(extract_if)]
let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
let evens = numbers.extract_if(|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]>§
sourcepub fn as_str(&self) -> &str
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_str(&self) -> &str
ascii_char
)Views this slice of ASCII characters as a UTF-8 str
.
sourcepub fn as_bytes(&self) -> &[u8] ⓘ
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_bytes(&self) -> &[u8] ⓘ
ascii_char
)Views this slice of ASCII characters as a slice of u8
bytes.
1.23.0 · sourcepub fn is_ascii(&self) -> bool
pub fn is_ascii(&self) -> bool
Checks if all bytes in this slice are within the ASCII range.
sourcepub fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
)If this slice is_ascii
, returns it as a slice of
ASCII characters, otherwise returns None
.
sourcepub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
🔬This is a nightly-only experimental API. (ascii_char
)
pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
ascii_char
)Converts this slice of bytes into a slice of ASCII characters, without checking whether they’re valid.
§Safety
Every byte in the slice must be in 0..=127
, or else this is UB.
1.23.0 · sourcepub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
Checks that two slices are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
1.23.0 · sourcepub fn make_ascii_uppercase(&mut self)
pub fn make_ascii_uppercase(&mut self)
Converts this slice to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase
.
1.23.0 · sourcepub fn make_ascii_lowercase(&mut self)
pub fn make_ascii_lowercase(&mut self)
Converts this slice to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase
.
1.60.0 · sourcepub fn escape_ascii(&self) -> EscapeAscii<'_>
pub fn escape_ascii(&self) -> EscapeAscii<'_>
Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.
§Examples
let s = b"0\t\r\n'\"\\\x9d";
let escaped = s.escape_ascii().to_string();
assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
1.80.0 · sourcepub fn trim_ascii_start(&self) -> &[u8] ⓘ
pub fn trim_ascii_start(&self) -> &[u8] ⓘ
Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b" ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");
1.80.0 · sourcepub fn trim_ascii_end(&self) -> &[u8] ⓘ
pub fn trim_ascii_end(&self) -> &[u8] ⓘ
Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b" ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");
1.80.0 · sourcepub fn trim_ascii(&self) -> &[u8] ⓘ
pub fn trim_ascii(&self) -> &[u8] ⓘ
Returns a byte slice with leading and trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b" ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");
1.0.0 · sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Returns true
if the slice has a length of 0.
§Examples
let a = [1, 2, 3];
assert!(!a.is_empty());
let b: &[i32] = &[];
assert!(b.is_empty());
1.0.0 · sourcepub fn first(&self) -> Option<&T>
pub fn first(&self) -> Option<&T>
Returns the first element of the slice, or None
if it is empty.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());
let w: &[i32] = &[];
assert_eq!(None, w.first());
1.0.0 · sourcepub fn first_mut(&mut self) -> Option<&mut T>
pub fn first_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the first element of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some(first) = x.first_mut() {
*first = 5;
}
assert_eq!(x, &[5, 1, 2]);
let y: &mut [i32] = &mut [];
assert_eq!(None, y.first_mut());
1.5.0 · sourcepub fn split_first(&self) -> Option<(&T, &[T])>
pub fn split_first(&self) -> Option<(&T, &[T])>
Returns the first and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &[0, 1, 2];
if let Some((first, elements)) = x.split_first() {
assert_eq!(first, &0);
assert_eq!(elements, &[1, 2]);
}
1.5.0 · sourcepub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>
pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the first and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some((first, elements)) = x.split_first_mut() {
*first = 3;
elements[0] = 4;
elements[1] = 5;
}
assert_eq!(x, &[3, 4, 5]);
1.5.0 · sourcepub fn split_last(&self) -> Option<(&T, &[T])>
pub fn split_last(&self) -> Option<(&T, &[T])>
Returns the last and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &[0, 1, 2];
if let Some((last, elements)) = x.split_last() {
assert_eq!(last, &2);
assert_eq!(elements, &[0, 1]);
}
1.5.0 · sourcepub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>
pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the last and all the rest of the elements of the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some((last, elements)) = x.split_last_mut() {
*last = 3;
elements[0] = 4;
elements[1] = 5;
}
assert_eq!(x, &[4, 5, 3]);
1.0.0 · sourcepub fn last(&self) -> Option<&T>
pub fn last(&self) -> Option<&T>
Returns the last element of the slice, or None
if it is empty.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());
let w: &[i32] = &[];
assert_eq!(None, w.last());
1.0.0 · sourcepub fn last_mut(&mut self) -> Option<&mut T>
pub fn last_mut(&mut self) -> Option<&mut T>
Returns a mutable reference to the last item in the slice, or None
if it is empty.
§Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_mut() {
*last = 10;
}
assert_eq!(x, &[0, 1, 10]);
let y: &mut [i32] = &mut [];
assert_eq!(None, y.last_mut());
1.77.0 · sourcepub fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
Returns an array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());
1.77.0 · sourcepub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Returns a mutable array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(first) = x.first_chunk_mut::<2>() {
first[0] = 5;
first[1] = 4;
}
assert_eq!(x, &[5, 4, 2]);
assert_eq!(None, x.first_chunk_mut::<4>());
1.77.0 · sourcepub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
pub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
Returns an array reference to the first N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk::<2>() {
assert_eq!(first, &[0, 1]);
assert_eq!(elements, &[2]);
}
assert_eq!(None, x.split_first_chunk::<4>());
1.77.0 · sourcepub fn split_first_chunk_mut<const N: usize>(
&mut self,
) -> Option<(&mut [T; N], &mut [T])>
pub fn split_first_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T; N], &mut [T])>
Returns a mutable array reference to the first N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk_mut::<2>() {
first[0] = 3;
first[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[3, 4, 5]);
assert_eq!(None, x.split_first_chunk_mut::<4>());
1.77.0 · sourcepub fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
pub fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
Returns an array reference to the last N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk::<2>() {
assert_eq!(elements, &[0]);
assert_eq!(last, &[1, 2]);
}
assert_eq!(None, x.split_last_chunk::<4>());
1.77.0 · sourcepub fn split_last_chunk_mut<const N: usize>(
&mut self,
) -> Option<(&mut [T], &mut [T; N])>
pub fn split_last_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T], &mut [T; N])>
Returns a mutable array reference to the last N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk_mut::<2>() {
last[0] = 3;
last[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[5, 3, 4]);
assert_eq!(None, x.split_last_chunk_mut::<4>());
1.77.0 · sourcepub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
Returns an array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());
1.77.0 · sourcepub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Returns a mutable array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_chunk_mut::<2>() {
last[0] = 10;
last[1] = 20;
}
assert_eq!(x, &[0, 10, 20]);
assert_eq!(None, x.last_chunk_mut::<4>());
1.0.0 · sourcepub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
Returns a reference to an element or subslice depending on the type of index.
- If given a position, returns a reference to the element at that
position or
None
if out of bounds. - If given a range, returns the subslice corresponding to that range,
or
None
if out of bounds.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
1.0.0 · sourcepub fn get_mut<I>(
&mut self,
index: I,
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get_mut<I>(
&mut self,
index: I,
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
1.0.0 · sourcepub unsafe fn get_unchecked<I>(
&self,
index: I,
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked<I>(
&self,
index: I,
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a reference to an element or subslice, without doing bounds checking.
For a safe alternative see get
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get(index).unwrap_unchecked()
. It’s UB
to call .get_unchecked(len)
, even if you immediately convert to a
pointer. And it’s UB to call .get_unchecked(..len + 1)
,
.get_unchecked(..=len)
, or similar.
§Examples
let x = &[1, 2, 4];
unsafe {
assert_eq!(x.get_unchecked(1), &2);
}
1.0.0 · sourcepub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I,
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I,
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a mutable reference to an element or subslice, without doing bounds checking.
For a safe alternative see get_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get_mut(index).unwrap_unchecked()
. It’s
UB to call .get_unchecked_mut(len)
, even if you immediately convert
to a pointer. And it’s UB to call .get_unchecked_mut(..len + 1)
,
.get_unchecked_mut(..=len)
, or similar.
§Examples
let x = &mut [1, 2, 4];
unsafe {
let elem = x.get_unchecked_mut(1);
*elem = 13;
}
assert_eq!(x, &[1, 13, 4]);
1.0.0 · sourcepub fn as_ptr(&self) -> *const T
pub fn as_ptr(&self) -> *const T
Returns a raw pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up dangling.
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 dangling.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
§Examples
let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();
unsafe {
for i in 0..x.len() {
*x_ptr.add(i) += 2;
}
}
assert_eq!(x, &[3, 4, 6]);
1.48.0 · sourcepub fn as_ptr_range(&self) -> Range<*const T>
pub fn as_ptr_range(&self) -> Range<*const T>
Returns the two raw pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_ptr
for warnings on using these pointers. The end pointer
requires extra caution, as it does not point to a valid element in the
slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
It can also be useful to check if a pointer to an element refers to an element of this slice:
let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;
assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));
1.48.0 · sourcepub fn as_mut_ptr_range(&mut self) -> Range<*mut T>
pub fn as_mut_ptr_range(&mut self) -> Range<*mut T>
Returns the two unsafe mutable pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_mut_ptr
for warnings on using these pointers. The end
pointer requires extra caution, as it does not point to a valid element
in the slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
1.0.0 · sourcepub fn swap(&mut self, a: usize, b: usize)
pub fn swap(&mut self, a: usize, b: usize)
Swaps two elements in the slice.
If a
equals to b
, it’s guaranteed that elements won’t change value.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Panics
Panics if a
or b
are out of bounds.
§Examples
let mut v = ["a", "b", "c", "d", "e"];
v.swap(2, 4);
assert!(v == ["a", "b", "e", "d", "c"]);
sourcepub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
🔬This is a nightly-only experimental API. (slice_swap_unchecked
)
pub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
slice_swap_unchecked
)Swaps two elements in the slice, without doing bounds checking.
For a safe alternative see swap
.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Safety
Calling this method with an out-of-bounds index is undefined behavior.
The caller has to ensure that a < self.len()
and b < self.len()
.
§Examples
#![feature(slice_swap_unchecked)]
let mut v = ["a", "b", "c", "d"];
// SAFETY: we know that 1 and 3 are both indices of the slice
unsafe { v.swap_unchecked(1, 3) };
assert!(v == ["a", "d", "c", "b"]);
1.0.0 · sourcepub fn reverse(&mut self)
pub fn reverse(&mut self)
Reverses the order of elements in the slice, in place.
§Examples
let mut v = [1, 2, 3];
v.reverse();
assert!(v == [3, 2, 1]);
1.0.0 · sourcepub fn iter(&self) -> Iter<'_, T>
pub fn iter(&self) -> Iter<'_, T>
Returns an iterator over the slice.
The iterator yields all items from start to end.
§Examples
let x = &[1, 2, 4];
let mut iterator = x.iter();
assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);
1.0.0 · sourcepub fn iter_mut(&mut self) -> IterMut<'_, T>
pub fn iter_mut(&mut self) -> IterMut<'_, T>
Returns an iterator that allows modifying each value.
The iterator yields all items from start to end.
§Examples
let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
*elem += 2;
}
assert_eq!(x, &[3, 4, 6]);
1.0.0 · sourcepub fn windows(&self, size: usize) -> Windows<'_, T>
pub fn windows(&self, size: usize) -> Windows<'_, T>
Returns an iterator over all contiguous windows of length
size
. The windows overlap. If the slice is shorter than
size
, the iterator returns no values.
§Panics
Panics if size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.windows(3);
assert_eq!(iter.next().unwrap(), &['l', 'o', 'r']);
assert_eq!(iter.next().unwrap(), &['o', 'r', 'e']);
assert_eq!(iter.next().unwrap(), &['r', 'e', 'm']);
assert!(iter.next().is_none());
If the slice is shorter than size
:
let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());
There’s no windows_mut
, as that existing would let safe code violate the
“only one &mut
at a time to the same thing” rule. However, you can sometimes
use Cell::as_slice_of_cells
in
conjunction with windows
to accomplish something similar:
use std::cell::Cell;
let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
Cell::swap(&w[0], &w[2]);
}
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);
1.0.0 · sourcepub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See chunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and rchunks
for the same iterator but starting at the end of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());
1.0.0 · sourcepub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>
pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See chunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and rchunks_mut
for the same iterator but starting at
the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 3]);
1.31.0 · sourcepub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks
.
See chunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and rchunks_exact
for the same iterator but starting at the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
1.31.0 · sourcepub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>
pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See chunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and rchunks_exact_mut
for the same iterator but starting at the end of
the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
sourcepub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed
sourcepub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);
If you expect the slice to be an exact multiple, you can combine
let
-else
with an empty slice pattern:
#![feature(slice_as_chunks)]
let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
panic!("slice didn't have even length")
};
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);
sourcepub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
sourcepub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
🔬This is a nightly-only experimental API. (array_chunks
)
pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
array_chunks
)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are array references and do not overlap. If N
does not divide the
length of the slice, then the last up to N-1
elements will be omitted and can be
retrieved from the remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
sourcepub unsafe fn as_chunks_unchecked_mut<const N: usize>(
&mut self,
) -> &mut [[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub unsafe fn as_chunks_unchecked_mut<const N: usize>( &mut self, ) -> &mut [[T; N]]
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &mut [char] = &mut ['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &mut [[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked_mut() };
chunks[0] = ['L'];
assert_eq!(chunks, &[['L'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &mut [[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked_mut() };
chunks[1] = ['a', 'x', '?'];
assert_eq!(slice, &['L', 'o', 'r', 'a', 'x', '?']);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked_mut() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked_mut() // Zero-length chunks are never allowed
sourcepub fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (chunks, remainder) = v.as_chunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 9]);
sourcepub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])
slice_as_chunks
)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (remainder, chunks) = v.as_rchunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[9, 1, 1, 2, 2]);
sourcepub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>
🔬This is a nightly-only experimental API. (array_chunks
)
pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>
array_chunks
)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable array references and do not overlap. If N
does not divide
the length of the slice, then the last up to N-1
elements will be omitted and
can be retrieved from the into_remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact_mut
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.array_chunks_mut() {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
sourcepub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
🔬This is a nightly-only experimental API. (array_windows
)
pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
array_windows
)Returns an iterator over overlapping windows of N
elements of a slice,
starting at the beginning of the slice.
This is the const generic equivalent of windows
.
If N
is greater than the size of the slice, it will return no windows.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());
1.31.0 · sourcepub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See rchunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and chunks
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());
1.31.0 · sourcepub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>
pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See rchunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and chunks_mut
for the same iterator but starting at the
beginning of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);
1.31.0 · sourcepub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
end of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of rchunks
.
See rchunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and chunks_exact
for the same iterator but starting at the beginning of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);
1.31.0 · sourcepub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>
pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See rchunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and chunks_exact_mut
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);
1.77.0 · sourcepub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by(|a, b| a <= b);
assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);
1.77.0 · sourcepub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
pub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by_mut(|a, b| a == b);
assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
assert_eq!(iter.next(), Some(&mut [3, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by_mut(|a, b| a <= b);
assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3, 4][..]));
assert_eq!(iter.next(), None);
1.0.0 · sourcepub fn split_at(&self, mid: usize) -> (&[T], &[T])
pub fn split_at(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_checked
.
§Examples
let v = [1, 2, 3, 4, 5, 6];
{
let (left, right) = v.split_at(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
1.0.0 · sourcepub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_mut_checked
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_at_mut(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
1.79.0 · sourcepub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
let v = [1, 2, 3, 4, 5, 6];
unsafe {
let (left, right) = v.split_at_unchecked(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
1.79.0 · sourcepub unsafe fn split_at_mut_unchecked(
&mut self,
mid: usize,
) -> (&mut [T], &mut [T])
pub unsafe fn split_at_mut_unchecked( &mut self, mid: usize, ) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
unsafe {
let (left, right) = v.split_at_mut_unchecked(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
1.80.0 · sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
pub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
Divides one slice into two at an index, returning None
if the slice is
too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
let v = [1, -2, 3, -4, 5, -6];
{
let (left, right) = v.split_at_checked(0).unwrap();
assert_eq!(left, []);
assert_eq!(right, [1, -2, 3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(2).unwrap();
assert_eq!(left, [1, -2]);
assert_eq!(right, [3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(6).unwrap();
assert_eq!(left, [1, -2, 3, -4, 5, -6]);
assert_eq!(right, []);
}
assert_eq!(None, v.split_at_checked(7));
1.80.0 · sourcepub fn split_at_mut_checked(
&mut self,
mid: usize,
) -> Option<(&mut [T], &mut [T])>
pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut [T], &mut [T])>
Divides one mutable slice into two at an index, returning None
if the
slice is too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
if let Some((left, right)) = v.split_at_mut_checked(2) {
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
assert_eq!(None, v.split_at_mut_checked(7));
1.0.0 · sourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F>
pub fn split<F>(&self, pred: F) -> Split<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
. The matched element is not contained in the subslices.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:
let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());
If two matched elements are directly adjacent, an empty slice will be present between them:
let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
1.0.0 · sourcepub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F>
pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
. The matched element is not contained in the subslices.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_mut(|num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 1]);
1.51.0 · sourcepub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
. The matched element is contained in the end of the previous
subslice as a terminator.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.
let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());
1.51.0 · sourcepub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>
pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
. The matched element is contained in the previous
subslice as a terminator.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
let terminator_idx = group.len()-1;
group[terminator_idx] = 1;
}
assert_eq!(v, [10, 40, 1, 20, 1, 1]);
1.27.0 · sourcepub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>
pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
, starting at the end of the slice and working backwards.
The matched element is not contained in the subslices.
§Examples
let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);
assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);
As with split()
, if the first or last element is matched, an empty
slice will be the first (or last) item returned by the iterator.
let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);
1.27.0 · sourcepub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F>
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that
match pred
, starting at the end of the slice and working
backwards. The matched element is not contained in the subslices.
§Examples
let mut v = [100, 400, 300, 200, 600, 500];
let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
count += 1;
group[0] = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);
1.0.0 · sourcepub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once by numbers divisible by 3 (i.e., [10, 40]
,
[20, 60, 50]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.splitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
1.0.0 · sourcepub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F>
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F>
Returns an iterator over mutable subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.splitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);
1.0.0 · sourcepub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once, starting from the end, by numbers divisible
by 3 (i.e., [50]
, [10, 40, 30, 20]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.rsplitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
1.0.0 · sourcepub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut s = [10, 40, 30, 20, 60, 50];
for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);
sourcepub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
)Splits the slice on the first element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.split_once(|&x| x == 2), Some((
&[1][..],
&[3, 2, 4][..]
)));
assert_eq!(s.split_once(|&x| x == 0), None);
sourcepub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
)Splits the slice on the last element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.rsplit_once(|&x| x == 2), Some((
&[1, 2, 3][..],
&[4][..]
)));
assert_eq!(s.rsplit_once(|&x| x == 0), None);
1.0.0 · sourcepub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
pub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
Returns true
if the slice contains an element with the given value.
This operation is O(n).
Note that if you have a sorted slice, binary_search
may be faster.
§Examples
let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));
If you do not have a &T
, but some other value that you can compare
with one (for example, String
implements PartialEq<str>
), you can
use iter().any
:
let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));
1.0.0 · sourcepub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a prefix of the slice or equal to the slice.
§Examples
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(v.starts_with(&v));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));
1.0.0 · sourcepub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a suffix of the slice or equal to the slice.
§Examples
let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(v.ends_with(&v));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));
1.51.0 · sourcepub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
Returns a subslice with the prefix removed.
If the slice starts with prefix
, returns the subslice after the prefix, wrapped in Some
.
If prefix
is empty, simply returns the original slice. If prefix
is equal to the
original slice, returns an empty slice.
If the slice does not start with prefix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);
let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
Some(b"llo".as_ref()));
1.51.0 · sourcepub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
Returns a subslice with the suffix removed.
If the slice ends with suffix
, returns the subslice before the suffix, wrapped in Some
.
If suffix
is empty, simply returns the original slice. If suffix
is equal to the
original slice, returns an empty slice.
If the slice does not end with suffix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);
1.0.0 · sourcepub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
pub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
Binary searches this slice for a given element. If the slice is not sorted, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search_by
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
assert_eq!(s.binary_search(&13), Ok(9));
assert_eq!(s.binary_search(&4), Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });
If you want to find that whole range of matching items, rather than
an arbitrary matching one, that can be done using partition_point
:
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));
assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));
// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));
If you want to insert an item to a sorted vector, while maintaining
sort order, consider using partition_point
:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
// If `num` is unique, `s.partition_point(|&x| x < num)` (with `<`) is equivalent to
// `s.binary_search(&num).unwrap_or_else(|x| x)`, but using `<=` will allow `insert`
// to shift less elements.
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
1.0.0 · sourcepub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
Binary searches this slice with a comparator function.
The comparator function should return an order code that indicates
whether its argument is Less
, Equal
or Greater
the desired
target.
If the slice is not sorted or if the comparator function does not
implement an order consistent with the sort order of the underlying
slice, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });
1.10.0 · sourcepub fn binary_search_by_key<'a, B, F>(
&'a self,
b: &B,
f: F,
) -> Result<usize, usize>
pub fn binary_search_by_key<'a, B, F>( &'a self, b: &B, f: F, ) -> Result<usize, usize>
Binary searches this slice with a key extraction function.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
If the slice is not sorted by the key, the returned result is
unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by
, and partition_point
.
§Examples
Looks up a series of four elements in a slice of pairs sorted by
their second elements. The first is found, with a uniquely
determined position; the second and third are not found; the
fourth could match any position in [1, 4]
.
let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
(1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
(1, 21), (2, 34), (4, 55)];
assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });
1.20.0 · sourcepub fn sort_unstable(&mut self)where
T: Ord,
pub fn sort_unstable(&mut self)where
T: Ord,
Sorts the slice without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
If the implementation of Ord
for T
does not implement a total order the resulting
order of elements in the slice is unspecified. All original elements will remain in the
slice and any possible modifications via interior mutability are observed in the input. Same
is true if the implementation of Ord
for T
panics.
Sorting types that only implement PartialOrd
such as f32
and f64
require
additional precautions. For example, f32::NAN != f32::NAN
, which doesn’t fulfill the
reflexivity requirement of Ord
. By using an alternative comparison function with
slice::sort_unstable_by
such as f32::total_cmp
or f64::total_cmp
that defines a
total order users can sort slices containing floating-point values. Alternatively, if all
values in the slice are guaranteed to be in a subset for which PartialOrd::partial_cmp
forms a total order, it’s possible to sort the slice with sort_unstable_by(|a, b| a.partial_cmp(b).unwrap())
.
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
§Panics
May panic if the implementation of Ord
for T
does not implement a total order.
§Examples
let mut v = [4, -5, 1, -3, 2];
v.sort_unstable();
assert_eq!(v, [-5, -3, 1, 2, 4]);
1.20.0 · sourcepub fn sort_unstable_by<F>(&mut self, compare: F)
pub fn sort_unstable_by<F>(&mut self, compare: F)
Sorts the slice with a comparison function, without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
If the comparison function compare
does not implement a total order the resulting order
of elements in the slice is unspecified. All original elements will remain in the slice and
any possible modifications via interior mutability are observed in the input. Same is true
if compare
panics.
For example |a, b| (a - b).cmp(a)
is a comparison function that is neither transitive nor
reflexive nor total, a < b < c < a
with a = 1, b = 2, c = 3
. For more information and
examples see the Ord
documentation.
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
§Panics
May panic if compare
does not implement a total order.
§Examples
let mut v = [4, -5, 1, -3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert_eq!(v, [-5, -3, 1, 2, 4]);
// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert_eq!(v, [4, 2, 1, -3, -5]);
1.20.0 · sourcepub fn sort_unstable_by_key<K, F>(&mut self, f: F)
pub fn sort_unstable_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, without preserving the initial order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
If the implementation of Ord
for K
does not implement a total order the resulting
order of elements in the slice is unspecified. All original elements will remain in the
slice and any possible modifications via interior mutability are observed in the input. Same
is true if the implementation of Ord
for K
panics.
§Current implementation
The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.
§Panics
May panic if the implementation of Ord
for K
does not implement a total order.
§Examples
let mut v = [4i32, -5, 1, -3, 2];
v.sort_unstable_by_key(|k| k.abs());
assert_eq!(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,
Reorders the slice such that the element at index
after the reordering is at its final
sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
. Additionally, this reordering is
unstable (i.e. any number of equal elements may end up at position index
), in-place (i.e.
does not allocate), and runs in O(n) time. This function is also known as “kth element”
in other libraries.
It returns a triplet of the following from the reordered slice: the subslice prior to
index
, the element at index
, and the subslice after index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and
greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
May panic if the implementation of Ord
for T
does not implement a total order.
§Examples
let mut v = [-5i32, 4, 2, -3, 1];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median.
let (lesser, median, greater) = v.select_nth_unstable(2);
assert!(lesser == [-3, -5] || lesser == [-5, -3]);
assert_eq!(median, &mut 1);
assert!(greater == [4, 2] || greater == [2, 4]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
v == [-5, -3, 1, 2, 4] ||
v == [-3, -5, 1, 4, 2] ||
v == [-5, -3, 1, 4, 2]);
1.49.0 · sourcepub fn select_nth_unstable_by<F>(
&mut self,
index: usize,
compare: F,
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by<F>( &mut self, index: usize, compare: F, ) -> (&mut [T], &mut T, &mut [T])
Reorders the slice with a comparator function such that the element at index
after the
reordering is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the comparator function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time. This
function is also known as “kth element” in other libraries.
It returns a triplet of the following from the slice reordered according to the provided
comparator function: the subslice prior to index
, the element at index
, and the subslice
after index
; accordingly, the values in those two subslices will respectively all be
less-than-or-equal-to and greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
May panic if compare
does not implement a total order.
§Examples
let mut v = [-5i32, 4, 2, -3, 1];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted in descending order.
let (lesser, median, greater) = v.select_nth_unstable_by(2, |a, b| b.cmp(a));
assert!(lesser == [4, 2] || lesser == [2, 4]);
assert_eq!(median, &mut 1);
assert!(greater == [-3, -5] || greater == [-5, -3]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
v == [2, 4, 1, -3, -5] ||
v == [4, 2, 1, -5, -3] ||
v == [4, 2, 1, -3, -5]);
1.49.0 · sourcepub fn select_nth_unstable_by_key<K, F>(
&mut self,
index: usize,
f: F,
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by_key<K, F>( &mut self, index: usize, f: F, ) -> (&mut [T], &mut T, &mut [T])
Reorders the slice with a key extraction function such that the element at index
after the
reordering is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the key extraction function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time. This
function is also known as “kth element” in other libraries.
It returns a triplet of the following from the slice reordered according to the provided key
extraction function: the subslice prior to index
, the element at index
, and the subslice
after index
; accordingly, the values in those two subslices will respectively all be
less-than-or-equal-to and greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll
and Orson Peters, which is also the basis for sort_unstable
. The fallback algorithm is
Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime
for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
May panic if K: Ord
does not implement a total order.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted according to absolute value.
let (lesser, median, greater) = v.select_nth_unstable_by_key(2, |a| a.abs());
assert!(lesser == [1, 2] || lesser == [2, 1]);
assert_eq!(median, &mut -3);
assert!(greater == [4, -5] || greater == [-5, 4]);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
v == [1, 2, -3, -5, 4] ||
v == [2, 1, -3, 4, -5] ||
v == [2, 1, -3, -5, 4]);
sourcepub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
slice_partition_dedup
)Moves all consecutive repeated elements to the end of the slice according to the
PartialEq
trait implementation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];
let (dedup, duplicates) = slice.partition_dedup();
assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);
sourcepub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
slice_partition_dedup
)Moves all but the first of consecutive elements to the end of the slice satisfying a given equality relation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
The same_bucket
function is passed references to two elements from the slice and
must determine if the elements compare equal. The elements are passed in opposite order
from their order in the slice, so if same_bucket(a, b)
returns true
, a
is moved
at the end of the slice.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];
let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);
sourcepub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
)
pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
slice_partition_dedup
)Moves all but the first of consecutive elements to the end of the slice that resolve to the same key.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];
let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);
assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);
1.26.0 · sourcepub fn rotate_left(&mut self, mid: usize)
pub fn rotate_left(&mut self, mid: usize)
Rotates the slice in-place such that the first mid
elements of the
slice move to the end while the last self.len() - mid
elements move to
the front.
After calling rotate_left
, the element previously at index mid
will
become the first element in the slice.
§Panics
This function will panic if mid
is greater than the length of the
slice. Note that mid == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
Rotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
1.26.0 · sourcepub fn rotate_right(&mut self, k: usize)
pub fn rotate_right(&mut self, k: usize)
Rotates the slice in-place such that the first self.len() - k
elements of the slice move to the end while the last k
elements move
to the front.
After calling rotate_right
, the element previously at index
self.len() - k
will become the first element in the slice.
§Panics
This function will panic if k
is greater than the length of the
slice. Note that k == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
Rotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
1.50.0 · sourcepub fn fill(&mut self, value: T)where
T: Clone,
pub fn fill(&mut self, value: T)where
T: Clone,
Fills self
with elements by cloning value
.
§Examples
let mut buf = vec![0; 10];
buf.fill(1);
assert_eq!(buf, vec![1; 10]);
1.51.0 · sourcepub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
pub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
Fills self
with elements returned by calling a closure repeatedly.
This method uses a closure to create new values. If you’d rather
Clone
a given value, use fill
. If you want to use the Default
trait to generate values, you can pass Default::default
as the
argument.
§Examples
let mut buf = vec![1; 10];
buf.fill_with(Default::default);
assert_eq!(buf, vec![0; 10]);
1.7.0 · sourcepub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
pub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
Copies the elements from src
into self
.
The length of src
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Cloning two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use clone_from_slice
on a
single slice will result in a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].clone_from_slice(&slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.clone_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
1.9.0 · sourcepub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
pub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
Copies all elements from src
into self
, using a memcpy.
The length of src
must be the same as self
.
If T
does not implement Copy
, use clone_from_slice
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Copying two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
Rust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use copy_from_slice
on a
single slice will result in a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].copy_from_slice(&slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.copy_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
1.37.0 · sourcepub fn copy_within<R>(&mut self, src: R, dest: usize)
pub fn copy_within<R>(&mut self, src: R, dest: usize)
Copies elements from one part of the slice to another part of itself, using a memmove.
src
is the range within self
to copy from. dest
is the starting
index of the range within self
to copy to, which will have the same
length as src
. The two ranges may overlap. The ends of the two ranges
must be less than or equal to self.len()
.
§Panics
This function will panic if either range exceeds the end of the slice,
or if the end of src
is before the start.
§Examples
Copying four bytes within a slice:
let mut bytes = *b"Hello, World!";
bytes.copy_within(1..5, 8);
assert_eq!(&bytes, b"Hello, Wello!");
1.27.0 · sourcepub fn swap_with_slice(&mut self, other: &mut [T])
pub fn swap_with_slice(&mut self, other: &mut [T])
Swaps all elements in self
with those in other
.
The length of other
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Example
Swapping two elements across slices:
let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];
slice1.swap_with_slice(&mut slice2[2..]);
assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);
Rust enforces that there can only be one mutable reference to a
particular piece of data in a particular scope. Because of this,
attempting to use swap_with_slice
on a single slice will result in
a compile failure:
let mut slice = [1, 2, 3, 4, 5];
slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!
To work around this, we can use split_at_mut
to create two distinct
mutable sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.swap_with_slice(&mut right[1..]);
}
assert_eq!(slice, [4, 5, 3, 1, 2]);
1.30.0 · sourcepub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
Transmutes the slice to a slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
1.30.0 · sourcepub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
Transmutes the mutable slice to a mutable slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
sourcepub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
🔬This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
portable_simd
)Splits a slice into a prefix, a middle of aligned SIMD types, and a suffix.
This is a safe wrapper around slice::align_to
, so inherits the same
guarantees as that method.
§Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like LANES == 3
.
§Examples
#![feature(portable_simd)]
use core::simd::prelude::*;
let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle
// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);
fn basic_simd_sum(x: &[f32]) -> f32 {
use std::ops::Add;
let (prefix, middle, suffix) = x.as_simd();
let sums = f32x4::from_array([
prefix.iter().copied().sum(),
0.0,
0.0,
suffix.iter().copied().sum(),
]);
let sums = middle.iter().copied().fold(sums, f32x4::add);
sums.reduce_sum()
}
let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);
sourcepub fn as_simd_mut<const LANES: usize>(
&mut self,
) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
🔬This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd_mut<const LANES: usize>( &mut self, ) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
portable_simd
)Splits a mutable slice into a mutable prefix, a middle of aligned SIMD types, and a mutable suffix.
This is a safe wrapper around slice::align_to_mut
, so inherits the same
guarantees as that method.
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
.
1.82.0 · sourcepub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
pub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
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
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());
1.82.0 · sourcepub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
pub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
Checks if the elements of this slice are sorted using the given comparator function.
Instead of using PartialOrd::partial_cmp
, this function uses the given compare
function to determine whether two elements are to be considered in sorted order.
§Examples
assert!([1, 2, 2, 9].is_sorted_by(|a, b| a <= b));
assert!(![1, 2, 2, 9].is_sorted_by(|a, b| a < b));
assert!([0].is_sorted_by(|a, b| true));
assert!([0].is_sorted_by(|a, b| false));
let empty: [i32; 0] = [];
assert!(empty.is_sorted_by(|a, b| false));
assert!(empty.is_sorted_by(|a, b| true));
1.82.0 · sourcepub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
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
assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
1.52.0 · sourcepub fn partition_point<P>(&self, pred: P) -> usize
pub fn partition_point<P>(&self, pred: P) -> usize
Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).
The slice is assumed to be partitioned according to the given predicate.
This means that all elements for which the predicate returns true are at the start of the slice
and all elements for which the predicate returns false are at the end.
For example, [7, 15, 3, 5, 4, 12, 6]
is partitioned under the predicate x % 2 != 0
(all odd numbers are at the start, all even at the end).
If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.
See also binary_search
, binary_search_by
, and binary_search_by_key
.
§Examples
let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);
assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));
If all elements of the slice match the predicate, including if the slice is empty, then the length of the slice will be returned:
let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);
If you want to insert an item to a sorted vector, while maintaining sort order:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
sourcepub fn take<'a, R>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take<'a, R>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
slice_take
)Removes the subslice corresponding to the given range and returns a reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut first_three = slice.take(..3).unwrap();
assert_eq!(slice, &['d']);
assert_eq!(first_three, &['a', 'b', 'c']);
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut tail = slice.take(2..).unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(tail, &['c', 'd']);
Getting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take(5..));
assert_eq!(None, slice.take(..5));
assert_eq!(None, slice.take(..=4));
let expected: &[char] = &['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take(..4));
sourcepub fn take_mut<'a, R>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_mut<'a, R>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
slice_take
)Removes the subslice corresponding to the given range and returns a mutable reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut first_three = slice.take_mut(..3).unwrap();
assert_eq!(slice, &mut ['d']);
assert_eq!(first_three, &mut ['a', 'b', 'c']);
Taking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut tail = slice.take_mut(2..).unwrap();
assert_eq!(slice, &mut ['a', 'b']);
assert_eq!(tail, &mut ['c', 'd']);
Getting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take_mut(5..));
assert_eq!(None, slice.take_mut(..5));
assert_eq!(None, slice.take_mut(..=4));
let expected: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take_mut(..4));
sourcepub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
)Removes the first element of the slice and returns a reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c'];
let first = slice.take_first().unwrap();
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'a');
sourcepub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
)Removes the first element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let first = slice.take_first_mut().unwrap();
*first = 'd';
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'d');
sourcepub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
)Removes the last element of the slice and returns a reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c'];
let last = slice.take_last().unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'c');
sourcepub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
)
pub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
)Removes the last element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let last = slice.take_last_mut().unwrap();
*last = 'd';
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'d');
sourcepub unsafe fn get_many_unchecked_mut<const N: usize>(
&mut self,
indices: [usize; N],
) -> [&mut T; N]
🔬This is a nightly-only experimental API. (get_many_mut
)
pub unsafe fn get_many_unchecked_mut<const N: usize>( &mut self, indices: [usize; N], ) -> [&mut T; N]
get_many_mut
)Returns mutable references to many indices at once, without doing any checks.
For a safe alternative see get_many_mut
.
§Safety
Calling this method with overlapping or out-of-bounds indices is undefined behavior even if the resulting references are not used.
§Examples
#![feature(get_many_mut)]
let x = &mut [1, 2, 4];
unsafe {
let [a, b] = x.get_many_unchecked_mut([0, 2]);
*a *= 10;
*b *= 100;
}
assert_eq!(x, &[10, 2, 400]);
sourcepub fn get_many_mut<const N: usize>(
&mut self,
indices: [usize; N],
) -> Result<[&mut T; N], GetManyMutError<N>>
🔬This is a nightly-only experimental API. (get_many_mut
)
pub fn get_many_mut<const N: usize>( &mut self, indices: [usize; N], ) -> Result<[&mut T; N], GetManyMutError<N>>
get_many_mut
)Returns mutable references to many indices at once.
Returns an error if any index is out-of-bounds, or if the same index was passed more than once.
§Examples
#![feature(get_many_mut)]
let v = &mut [1, 2, 3];
if let Ok([a, b]) = v.get_many_mut([0, 2]) {
*a = 413;
*b = 612;
}
assert_eq!(v, &[413, 2, 612]);
sourcepub fn elem_offset(&self, element: &T) -> Option<usize>
🔬This is a nightly-only experimental API. (substr_range
)
pub fn elem_offset(&self, element: &T) -> Option<usize>
substr_range
)Returns the index that an element reference points to.
Returns None
if element
does not point within the slice or if it points between elements.
This method is useful for extending slice iterators like slice::split
.
Note that this uses pointer arithmetic and does not compare elements.
To find the index of an element via comparison, use
.iter().position()
instead.
§Panics
Panics if T
is zero-sized.
§Examples
Basic usage:
#![feature(substr_range)]
let nums: &[u32] = &[1, 7, 1, 1];
let num = &nums[2];
assert_eq!(num, &1);
assert_eq!(nums.elem_offset(num), Some(2));
Returning None
with an in-between element:
#![feature(substr_range)]
let arr: &[[u32; 2]] = &[[0, 1], [2, 3]];
let flat_arr: &[u32] = arr.as_flattened();
let ok_elm: &[u32; 2] = flat_arr[0..2].try_into().unwrap();
let weird_elm: &[u32; 2] = flat_arr[1..3].try_into().unwrap();
assert_eq!(ok_elm, &[0, 1]);
assert_eq!(weird_elm, &[1, 2]);
assert_eq!(arr.elem_offset(ok_elm), Some(0)); // Points to element 0
assert_eq!(arr.elem_offset(weird_elm), None); // Points between element 0 and 1
sourcepub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>
🔬This is a nightly-only experimental API. (substr_range
)
pub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>
substr_range
)Returns the range of indices that a subslice points to.
Returns None
if subslice
does not point within the slice or if it points between elements.
This method does not compare elements. Instead, this method finds the location in the slice that
subslice
was obtained from. To find the index of a subslice via comparison, instead use
.windows()
.position()
.
This method is useful for extending slice iterators like slice::split
.
Note that this may return a false positive (either Some(0..0)
or Some(self.len()..self.len())
)
if subslice
has a length of zero and points to the beginning or end of another, separate, slice.
§Panics
Panics if T
is zero-sized.
§Examples
Basic usage:
#![feature(substr_range)]
let nums = &[0, 5, 10, 0, 0, 5];
let mut iter = nums
.split(|t| *t == 0)
.map(|n| nums.subslice_range(n).unwrap());
assert_eq!(iter.next(), Some(0..0));
assert_eq!(iter.next(), Some(1..3));
assert_eq!(iter.next(), Some(4..4));
assert_eq!(iter.next(), Some(5..6));
1.80.0 · sourcepub fn as_flattened(&self) -> &[T]
pub fn as_flattened(&self) -> &[T]
Takes a &[[T; N]]
, and flattens it to a &[T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
assert_eq!([[1, 2, 3], [4, 5, 6]].as_flattened(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].as_flattened(),
[[1, 2], [3, 4], [5, 6]].as_flattened(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.as_flattened().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.as_flattened().is_empty());
1.80.0 · sourcepub fn as_flattened_mut(&mut self) -> &mut [T]
pub fn as_flattened_mut(&mut self) -> &mut [T]
Takes a &mut [[T; N]]
, and flattens it to a &mut [T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
fn add_5_to_all(slice: &mut [i32]) {
for i in slice {
*i += 5;
}
}
let mut array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
add_5_to_all(array.as_flattened_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
)
pub fn sort_floats(&mut self)
sort_floats
)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f32::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
)
pub fn sort_floats(&mut self)
sort_floats
)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f64::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
1.79.0 · sourcepub fn utf8_chunks(&self) -> Utf8Chunks<'_>
pub fn utf8_chunks(&self) -> Utf8Chunks<'_>
Creates an iterator over the contiguous valid UTF-8 ranges of this slice, and the non-UTF-8 fragments in between.
§Examples
This function formats arbitrary but mostly-UTF-8 bytes into Rust source
code in the form of a C-string literal (c"..."
).
use std::fmt::Write as _;
pub fn cstr_literal(bytes: &[u8]) -> String {
let mut repr = String::new();
repr.push_str("c\"");
for chunk in bytes.utf8_chunks() {
for ch in chunk.valid().chars() {
// Escapes \0, \t, \r, \n, \\, \', \", and uses \u{...} for non-printable characters.
write!(repr, "{}", ch.escape_debug()).unwrap();
}
for byte in chunk.invalid() {
write!(repr, "\\x{:02X}", byte).unwrap();
}
}
repr.push('"');
repr
}
fn main() {
let lit = cstr_literal(b"\xferris the \xf0\x9f\xa6\x80\x07");
let expected = stringify!(c"\xFErris the 🦀\u{7}");
assert_eq!(lit, expected);
}
1.0.0 · sourcepub fn sort(&mut self)where
T: Ord,
pub fn sort(&mut self)where
T: Ord,
Sorts the slice, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
If the implementation of Ord
for T
does not implement a total order the resulting
order of elements in the slice is unspecified. All original elements will remain in the
slice and any possible modifications via interior mutability are observed in the input. Same
is true if the implementation of Ord
for T
panics.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory. See
sort_unstable
. The exception are partially sorted slices, which
may be better served with slice::sort
.
Sorting types that only implement PartialOrd
such as f32
and f64
require
additional precautions. For example, f32::NAN != f32::NAN
, which doesn’t fulfill the
reflexivity requirement of Ord
. By using an alternative comparison function with
slice::sort_by
such as f32::total_cmp
or f64::total_cmp
that defines a total
order users can sort slices containing floating-point values. Alternatively, if all values
in the slice are guaranteed to be in a subset for which PartialOrd::partial_cmp
forms a
total order, it’s possible to sort the slice with sort_by(|a, b| a.partial_cmp(b).unwrap())
.
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
§Panics
May panic if the implementation of Ord
for T
does not implement a total order.
§Examples
let mut v = [4, -5, 1, -3, 2];
v.sort();
assert_eq!(v, [-5, -3, 1, 2, 4]);
1.0.0 · sourcepub fn sort_by<F>(&mut self, compare: F)
pub fn sort_by<F>(&mut self, compare: F)
Sorts the slice with a comparison function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
If the comparison function compare
does not implement a total order the resulting order
of elements in the slice is unspecified. All original elements will remain in the slice and
any possible modifications via interior mutability are observed in the input. Same is true
if compare
panics.
For example |a, b| (a - b).cmp(a)
is a comparison function that is neither transitive nor
reflexive nor total, a < b < c < a
with a = 1, b = 2, c = 3
. For more information and
examples see the Ord
documentation.
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
§Panics
May panic if compare
does not implement a total order.
§Examples
let mut v = [4, -5, 1, -3, 2];
v.sort_by(|a, b| a.cmp(b));
assert_eq!(v, [-5, -3, 1, 2, 4]);
// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert_eq!(v, [4, 2, 1, -3, -5]);
1.7.0 · sourcepub fn sort_by_key<K, F>(&mut self, f: F)
pub fn sort_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).
If the implementation of Ord
for K
does not implement a total order the resulting
order of elements in the slice is unspecified. All original elements will remain in the
slice and any possible modifications via interior mutability are observed in the input. Same
is true if the implementation of Ord
for K
panics.
§Current implementation
The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).
The auxiliary memory allocation behavior depends on the input length. Short slices are
handled without allocation, medium sized slices allocate self.len()
and beyond that it
clamps at self.len() / 2
.
§Panics
May panic if the implementation of Ord
for K
does not implement a total order.
§Examples
let mut v = [4i32, -5, 1, -3, 2];
v.sort_by_key(|k| k.abs());
assert_eq!(v, [1, 2, -3, 4, -5]);
1.34.0 · sourcepub fn sort_by_cached_key<K, F>(&mut self, f: F)
pub fn sort_by_cached_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, preserving initial order of equal elements.
This sort is stable (i.e., does not reorder equal elements) and O(m * n + n * log(n)) worst-case, where the key function is O(m).
During sorting, the key function is called at most once per element, by using temporary storage to remember the results of key evaluation. The order of calls to the key function is unspecified and may change in future versions of the standard library.
If the implementation of Ord
for K
does not implement a total order the resulting
order of elements in the slice is unspecified. All original elements will remain in the
slice and any possible modifications via interior mutability are observed in the input. Same
is true if the implementation of Ord
for K
panics.
For simple key functions (e.g., functions that are property accesses or basic operations),
sort_by_key
is likely to be faster.
§Current implementation
The current implementation is based on instruction-parallel-network sort by Lukas Bergdoll, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on fully sorted and reversed inputs. And O(k * log(n)) where k is the number of distinct elements in the input. It leverages superscalar out-of-order execution capabilities commonly found in CPUs, to efficiently perform the operation.
In the worst case, the algorithm allocates temporary storage in a Vec<(K, usize)>
the
length of the slice.
§Panics
May panic if the implementation of Ord
for K
does not implement a total order.
§Examples
let mut v = [4i32, -5, 1, -3, 2, 10];
// Strings are sorted by lexicographical order.
v.sort_by_cached_key(|k| k.to_string());
assert_eq!(v, [-3, -5, 1, 10, 2, 4]);
1.0.0 · sourcepub fn to_vec(&self) -> Vec<T>where
T: Clone,
pub fn to_vec(&self) -> Vec<T>where
T: Clone,
Copies self
into a new Vec
.
§Examples
let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.
sourcepub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
allocator_api
)Copies self
into a new Vec
with an allocator.
§Examples
#![feature(allocator_api)]
use std::alloc::System;
let s = [10, 40, 30];
let x = s.to_vec_in(System);
// Here, `s` and `x` can be modified independently.
1.0.0 · sourcepub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output ⓘ
pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output ⓘ
Flattens a slice of T
into a single value Self::Output
.
§Examples
assert_eq!(["hello", "world"].concat(), "helloworld");
assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);
1.3.0 · sourcepub fn join<Separator>(
&self,
sep: Separator,
) -> <[T] as Join<Separator>>::Output ⓘ
pub fn join<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output ⓘ
Flattens a slice of T
into a single value Self::Output
, placing a
given separator between each.
§Examples
assert_eq!(["hello", "world"].join(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]);
assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);
1.0.0 · sourcepub fn connect<Separator>(
&self,
sep: Separator,
) -> <[T] as Join<Separator>>::Output ⓘ
👎Deprecated since 1.3.0: renamed to join
pub fn connect<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output ⓘ
Flattens a slice of T
into a single value Self::Output
, placing a
given separator between each.
§Examples
assert_eq!(["hello", "world"].connect(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> Vec<u8> ⓘ
pub fn to_ascii_uppercase(&self) -> Vec<u8> ⓘ
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase
.
1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> Vec<u8> ⓘ
pub fn to_ascii_lowercase(&self) -> Vec<u8> ⓘ
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase
.
Trait Implementations§
source§impl<'outer> Debug for DatumVecBorrow<'outer>
impl<'outer> Debug for DatumVecBorrow<'outer>
source§impl<'outer> Deref for DatumVecBorrow<'outer>
impl<'outer> Deref for DatumVecBorrow<'outer>
source§impl<'outer> DerefMut for DatumVecBorrow<'outer>
impl<'outer> DerefMut for DatumVecBorrow<'outer>
Auto Trait Implementations§
impl<'outer> Freeze for DatumVecBorrow<'outer>
impl<'outer> RefUnwindSafe for DatumVecBorrow<'outer>
impl<'outer> Send for DatumVecBorrow<'outer>
impl<'outer> Sync for DatumVecBorrow<'outer>
impl<'outer> Unpin for DatumVecBorrow<'outer>
impl<'outer> !UnwindSafe for DatumVecBorrow<'outer>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> FutureExt for T
impl<T> FutureExt for T
source§fn with_context(self, otel_cx: Context) -> WithContext<Self>
fn with_context(self, otel_cx: Context) -> WithContext<Self>
source§fn with_current_context(self) -> WithContext<Self>
fn with_current_context(self) -> WithContext<Self>
source§impl<T> Instrument for T
impl<T> Instrument for T
source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
source§impl<T> IntoRequest<T> for T
impl<T> IntoRequest<T> for T
source§fn into_request(self) -> Request<T>
fn into_request(self) -> Request<T>
T
in a tonic::Request
source§impl<T, U> OverrideFrom<Option<&T>> for Uwhere
U: OverrideFrom<T>,
impl<T, U> OverrideFrom<Option<&T>> for Uwhere
U: OverrideFrom<T>,
source§impl<T> Pointable for T
impl<T> Pointable for T
source§impl<P, R> ProtoType<R> for Pwhere
R: RustType<P>,
impl<P, R> ProtoType<R> for Pwhere
R: RustType<P>,
source§fn into_rust(self) -> Result<R, TryFromProtoError>
fn into_rust(self) -> Result<R, TryFromProtoError>
RustType::from_proto
.source§fn from_rust(rust: &R) -> P
fn from_rust(rust: &R) -> P
RustType::into_proto
.source§impl<'a, S, T> Semigroup<&'a S> for Twhere
T: Semigroup<S>,
impl<'a, S, T> Semigroup<&'a S> for Twhere
T: Semigroup<S>,
source§fn plus_equals(&mut self, rhs: &&'a S)
fn plus_equals(&mut self, rhs: &&'a S)
std::ops::AddAssign
, for types that do not implement AddAssign
.