Primitive Type slice
A dynamically-sized view into a contiguous sequence, [T]
. Contiguous here means that elements are laid out so that every element is the same distance from its neighbors.
See also the std::slice
module.
Slices are a view into a block of memory represented as a pointer and a length.
// slicing a Vec let vec = vec![1, 2, 3]; let int_slice = &vec[..]; // coercing an array to a slice let str_slice: &[&str] = &["one", "two", "three"];
Slices are either mutable or shared. The shared slice type is &[T]
, while the mutable slice type is &mut [T]
, where T
represents the element type. For example, you can mutate the block of memory that a mutable slice points to:
let mut x = [1, 2, 3]; let x = &mut x[..]; // Take a full slice of `x`. x[1] = 7; assert_eq!(x, &[1, 7, 3]);
As slices store the length of the sequence they refer to, they have twice the size of pointers to Sized
types. Also see the reference on dynamically sized types.
let pointer_size = std::mem::size_of::<&u8>(); assert_eq!(2 * pointer_size, std::mem::size_of::<&[u8]>()); assert_eq!(2 * pointer_size, std::mem::size_of::<*const [u8]>()); assert_eq!(2 * pointer_size, std::mem::size_of::<Box<[u8]>>()); assert_eq!(2 * pointer_size, std::mem::size_of::<Rc<[u8]>>());
Implementations
impl<T> [T]
pub const fn len(&self) -> usize
Returns the number of elements in the slice.
Examples
let a = [1, 2, 3]; assert_eq!(a.len(), 3);
pub const 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());
pub const 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());
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]);
pub const 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]); }
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]);
pub const 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]); }
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]);
pub const 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());
Returns a mutable pointer to the last item in the slice.
Examples
let x = &mut [0, 1, 2]; if let Some(last) = x.last_mut() { *last = 10; } assert_eq!(x, &[0, 1, 10]);
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));
pub fn get_mut<I>(
&mut self,
index: I
) -> Option<&mut <I as SliceIndex<[T]>>::Output> where
I: SliceIndex<[T]>,
Returns a mutable reference to an element or subslice depending on the type of index (see get
) or None
if the index is out of bounds.
Examples
let x = &mut [0, 1, 2]; if let Some(elem) = x.get_mut(1) { *elem = 42; } assert_eq!(x, &[0, 42, 2]);
pub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Output where
I: SliceIndex<[T]>,
Returns a reference to an element or subslice, without doing bounds checking.
For a safe alternative see get
.
Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
Examples
let x = &[1, 2, 4]; unsafe { assert_eq!(x.get_unchecked(1), &2); }
pub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I
) -> &mut <I as SliceIndex<[T]>>::Output where
I: SliceIndex<[T]>,
Returns a mutable reference to an element or subslice, without doing bounds checking.
For a safe alternative see get_mut
.
Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
Examples
let x = &mut [1, 2, 4]; unsafe { let elem = x.get_unchecked_mut(1); *elem = 13; } assert_eq!(x, &[1, 13, 4]);
pub const fn as_ptr(&self) -> *const T
Returns a raw pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
The caller must also ensure that the memory the pointer (non-transitively) points to is never written to (except inside an UnsafeCell
) using this pointer or any pointer derived from it. If you need to mutate the contents of the slice, use as_mut_ptr
.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
Examples
let x = &[1, 2, 4]; let x_ptr = x.as_ptr(); unsafe { for i in 0..x.len() { assert_eq!(x.get_unchecked(i), &*x_ptr.add(i)); } }
Returns an unsafe mutable pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
Examples
let x = &mut [1, 2, 4]; let x_ptr = x.as_mut_ptr(); unsafe { for i in 0..x.len() { *x_ptr.add(i) += 2; } } assert_eq!(x, &[3, 4, 6]);
impl<A> Iterator for Range<A> where A: Step, type Item = A;
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));
impl<A> Iterator for Range<A> where A: Step, type Item = A;
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++.
pub fn swap(&mut self, a: usize, b: usize)
Swaps two elements in the slice.
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"]; v.swap(1, 3); assert!(v == ["a", "d", "c", "b"]);
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]);
pub fn iter(&self) -> Iter<'_, T>
impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;
Returns an iterator over the slice.
Examples
let x = &[1, 2, 4]; let mut iterator = x.iter(); assert_eq!(iterator.next(), Some(&1)); assert_eq!(iterator.next(), Some(&2)); assert_eq!(iterator.next(), Some(&4)); assert_eq!(iterator.next(), None);
pub fn iter_mut(&mut self) -> IterMut<'_, T>
impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;
Returns an iterator that allows modifying each value.
Examples
let x = &mut [1, 2, 4]; for elem in x.iter_mut() { *elem += 2; } assert_eq!(x, &[3, 4, 6]);
pub fn windows(&self, size: usize) -> Windows<'_, T>
impl<'a, T> Iterator for Windows<'a, T> type Item = &'a [T];
Returns an iterator over all contiguous windows of length size
. The windows overlap. If the slice is shorter than size
, the iterator returns no values.
Panics
Panics if size
is 0.
Examples
let slice = ['r', 'u', 's', 't']; let mut iter = slice.windows(2); assert_eq!(iter.next().unwrap(), &['r', 'u']); assert_eq!(iter.next().unwrap(), &['u', 's']); assert_eq!(iter.next().unwrap(), &['s', 't']); assert!(iter.next().is_none());
If the slice is shorter than size
:
let slice = ['f', 'o', 'o']; let mut iter = slice.windows(4); assert!(iter.next().is_none());
pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
impl<'a, T> Iterator for Chunks<'a, T> type Item = &'a [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());
pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>
impl<'a, T> Iterator for ChunksMut<'a, T> type Item = &'a mut [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]);
pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
impl<'a, T> Iterator for ChunksExact<'a, T> type Item = &'a [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']);
pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>
impl<'a, T> Iterator for ChunksExactMut<'a, T> type Item = &'a mut [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]);
pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
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
pub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
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']);
pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
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']]);
pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
impl<'a, T, const N: usize> Iterator for ArrayChunks<'a, T, N> type Item = &'a [T; N];
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']);
pub unsafe fn as_chunks_unchecked_mut<const N: usize>(
&mut self
) -> &mut [[T; N]]
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
pub fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T])
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]);
pub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])
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]);
pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>
impl<'a, T, const N: usize> Iterator for ArrayChunksMut<'a, T, N> type Item = &'a mut [T; N];
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]);
pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
impl<'a, T, const N: usize> Iterator for ArrayWindows<'a, T, N> type Item = &'a [T; N];
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());
pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
impl<'a, T> Iterator for RChunks<'a, T> type Item = &'a [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());
pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>
impl<'a, T> Iterator for RChunksMut<'a, T> type Item = &'a mut [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]);
pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
impl<'a, T> Iterator for RChunksExact<'a, T> type Item = &'a [T];
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the resulting code better than in the case of chunks
.
See rchunks
for a variant of this iterator that also returns the remainder as a smaller chunk, and chunks_exact
for the same iterator but starting at the beginning of the slice.
Panics
Panics if chunk_size
is 0.
Examples
let slice = ['l', 'o', 'r', 'e', 'm']; let mut iter = slice.rchunks_exact(2); assert_eq!(iter.next().unwrap(), &['e', 'm']); assert_eq!(iter.next().unwrap(), &['o', 'r']); assert!(iter.next().is_none()); assert_eq!(iter.remainder(), &['l']);
pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>
impl<'a, T> Iterator for RChunksExactMut<'a, T> type Item = &'a mut [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]);
impl<'a, T, P> Iterator for GroupBy<'a, T, P> where T: 'a, P: FnMut(&T, &T) -> bool, type Item = &'a [T];
Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.
The predicate is called on two elements following themselves, it means the predicate is called on slice[0]
and slice[1]
then on slice[1]
and slice[2]
and so on.
Examples
#![feature(slice_group_by)] let slice = &[1, 1, 1, 3, 3, 2, 2, 2]; let mut iter = slice.group_by(|a, b| a == b); assert_eq!(iter.next(), Some(&[1, 1, 1][..])); assert_eq!(iter.next(), Some(&[3, 3][..])); assert_eq!(iter.next(), Some(&[2, 2, 2][..])); assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
#![feature(slice_group_by)] let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4]; let mut iter = slice.group_by(|a, b| a <= b); assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..])); assert_eq!(iter.next(), Some(&[2, 3][..])); assert_eq!(iter.next(), Some(&[2, 3, 4][..])); assert_eq!(iter.next(), None);
impl<'a, T, P> Iterator for GroupByMut<'a, T, P> where T: 'a, P: FnMut(&T, &T) -> bool, type Item = &'a mut [T];
Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.
The predicate is called on two elements following themselves, it means the predicate is called on slice[0]
and slice[1]
then on slice[1]
and slice[2]
and so on.
Examples
#![feature(slice_group_by)] let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2]; let mut iter = slice.group_by_mut(|a, b| a == b); assert_eq!(iter.next(), Some(&mut [1, 1, 1][..])); assert_eq!(iter.next(), Some(&mut [3, 3][..])); assert_eq!(iter.next(), Some(&mut [2, 2, 2][..])); assert_eq!(iter.next(), None);
This method can be used to extract the sorted subslices:
#![feature(slice_group_by)] let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4]; let mut iter = slice.group_by_mut(|a, b| a <= b); assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..])); assert_eq!(iter.next(), Some(&mut [2, 3][..])); assert_eq!(iter.next(), Some(&mut [2, 3, 4][..])); assert_eq!(iter.next(), None);
pub fn split_at(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index.
The first will contain all indices from [0, mid)
(excluding the index mid
itself) and the second will contain all indices from [mid, len)
(excluding the index len
itself).
Panics
Panics if mid > len
.
Examples
let v = [1, 2, 3, 4, 5, 6]; { let (left, right) = v.split_at(0); assert_eq!(left, []); assert_eq!(right, [1, 2, 3, 4, 5, 6]); } { let (left, right) = v.split_at(2); assert_eq!(left, [1, 2]); assert_eq!(right, [3, 4, 5, 6]); } { let (left, right) = v.split_at(6); assert_eq!(left, [1, 2, 3, 4, 5, 6]); assert_eq!(right, []); }
pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index.
The first will contain all indices from [0, mid)
(excluding the index mid
itself) and the second will contain all indices from [mid, len)
(excluding the index len
itself).
Panics
Panics if mid > len
.
Examples
let mut v = [1, 0, 3, 0, 5, 6]; let (left, right) = v.split_at_mut(2); assert_eq!(left, [1, 0]); assert_eq!(right, [3, 0, 5, 6]); left[1] = 2; right[1] = 4; assert_eq!(v, [1, 2, 3, 4, 5, 6]);
impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a [T];
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());
impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a mut [T];
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]);
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
F: FnMut(&T) -> bool,
impl<'a, T, P> Iterator for SplitInclusive<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a [T];
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());
pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F> where
F: FnMut(&T) -> bool,
impl<'a, T, P> Iterator for SplitInclusiveMut<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a mut [T];
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]);
impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a [T];
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);
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F> where
F: FnMut(&T) -> bool,
impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a mut [T];
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]);
impl<'a, T, P> Iterator for SplitN<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a [T];
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); }
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F> where
F: FnMut(&T) -> bool,
impl<'a, T, P> Iterator for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a mut [T];
Returns an iterator over subslices separated by elements that match pred
, limited to returning at most n
items. The matched element is not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
Examples
let mut v = [10, 40, 30, 20, 60, 50]; for group in v.splitn_mut(2, |num| *num % 3 == 0) { group[0] = 1; } assert_eq!(v, [1, 40, 30, 1, 60, 50]);
impl<'a, T, P> Iterator for RSplitN<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a [T];
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); }
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F> where
F: FnMut(&T) -> bool,
impl<'a, T, P> Iterator for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool, type Item = &'a mut [T];
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]);
Returns true
if the slice contains an element with the given value.
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"));
Returns true
if needle
is a prefix of the slice.
Examples
let v = [10, 40, 30]; assert!(v.starts_with(&[10])); assert!(v.starts_with(&[10, 40])); assert!(!v.starts_with(&[50])); assert!(!v.starts_with(&[10, 50]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30]; assert!(v.starts_with(&[])); let v: &[u8] = &[]; assert!(v.starts_with(&[]));
Returns true
if needle
is a suffix of the slice.
Examples
let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30]; assert!(v.ends_with(&[])); let v: &[u8] = &[]; assert!(v.ends_with(&[]));
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
Returns a subslice with the prefix removed.
If the slice starts with prefix
, returns the subslice after the prefix, wrapped in Some
. If prefix
is empty, simply returns the original slice.
If the slice does not start with prefix
, returns None
.
Examples
let v = &[10, 40, 30]; assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..])); assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..])); assert_eq!(v.strip_prefix(&[50]), None); assert_eq!(v.strip_prefix(&[10, 50]), None); let prefix : &str = "he"; assert_eq!(b"hello".strip_prefix(prefix.as_bytes()), Some(b"llo".as_ref()));
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
Returns a subslice with the suffix removed.
If the slice ends with suffix
, returns the subslice before the suffix, wrapped in Some
. If suffix
is empty, simply returns the original slice.
If the slice does not end with suffix
, returns None
.
Examples
let v = &[10, 40, 30]; assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..])); assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..])); assert_eq!(v.strip_suffix(&[50]), None); assert_eq!(v.strip_suffix(&[50, 30]), None);
Binary searches this sorted slice for a given element.
If the value is found then Result::Ok
is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. The index is chosen deterministically, but is subject to change in future versions of Rust. If the value is not found then Result::Err
is returned, containing the index where a matching element could be inserted while maintaining sorted order.
See also binary_search_by
, binary_search_by_key
, and partition_point
.
Examples
Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; assert_eq!(s.binary_search(&13), Ok(9)); assert_eq!(s.binary_search(&4), Err(7)); assert_eq!(s.binary_search(&100), Err(13)); let r = s.binary_search(&1); assert!(match r { Ok(1..=4) => true, _ => false, });
If you want to insert an item to a sorted vector, while maintaining sort order:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; let num = 42; let idx = s.binary_search(&num).unwrap_or_else(|x| x); s.insert(idx, num); assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Binary searches this sorted slice with a comparator function.
The comparator function should implement an order consistent with the sort order of the underlying slice, returning an order code that indicates whether its argument is Less
, Equal
or Greater
the desired target.
If the value is found then Result::Ok
is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. The index is chosen deterministically, but is subject to change in future versions of Rust. If the value is not found then Result::Err
is returned, containing the index where a matching element could be inserted while maintaining sorted order.
See also binary_search
, binary_search_by_key
, and partition_point
.
Examples
Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; let seek = 13; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9)); let seek = 4; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7)); let seek = 100; assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13)); let seek = 1; let r = s.binary_search_by(|probe| probe.cmp(&seek)); assert!(match r { Ok(1..=4) => true, _ => false, });
Binary searches this sorted 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 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, });
Sorts the slice, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
Examples
let mut v = [-5, 4, 1, -3, 2]; v.sort_unstable(); assert!(v == [-5, -3, 1, 2, 4]);
Sorts the slice with a comparator function, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified. An order is a total order if it is (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0]; floats.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap()); assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
Examples
let mut v = [5, 4, 1, 3, 2]; v.sort_unstable_by(|a, b| a.cmp(b)); assert!(v == [1, 2, 3, 4, 5]); // reverse sorting v.sort_unstable_by(|a, b| b.cmp(a)); assert!(v == [5, 4, 3, 2, 1]);
Sorts the slice with a key extraction function, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(m * n * log(n)) worst-case, where the key function is O(m).
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
Due to its key calling strategy, sort_unstable_by_key
is likely to be slower than sort_by_cached_key
in cases where the key function is expensive.
Examples
let mut v = [-5i32, 4, 1, -3, 2]; v.sort_unstable_by_key(|k| k.abs()); assert!(v == [1, 2, -3, 4, -5]);
pub fn partition_at_index(
&mut self,
index: usize
) -> (&mut [T], &mut T, &mut [T]) where
T: Ord,
use the select_nth_unstable() instead
Reorder the slice such that the element at index
is at its final sorted position.
pub fn partition_at_index_by<F>(
&mut self,
index: usize,
compare: F
) -> (&mut [T], &mut T, &mut [T]) where
F: FnMut(&T, &T) -> Ordering,
use select_nth_unstable_by() instead
Reorder the slice with a comparator function such that the element at index
is at its final sorted position.
pub fn partition_at_index_by_key<K, F>(
&mut self,
index: usize,
f: F
) -> (&mut [T], &mut T, &mut [T]) where
F: FnMut(&T) -> K,
K: Ord,
use the select_nth_unstable_by_key() instead
Reorder the slice with a key extraction function such that the element at index
is at its final sorted position.
Reorder the slice such that the element at index
is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be less than or equal to any value at a position j > index
. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index
), in-place (i.e. does not allocate), and O(n) worst-case. This function is also/ known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2]; // Find the median v.select_nth_unstable(2); // We are only guaranteed the slice will be one of the following, based on the way we sort // about the specified index. assert!(v == [-3, -5, 1, 2, 4] || v == [-5, -3, 1, 2, 4] || v == [-3, -5, 1, 4, 2] || v == [-5, -3, 1, 4, 2]);
Reorder the slice with a comparator function such that the element at index
is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be less than or equal to any value at a position j > index
using the comparator function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index
), in-place (i.e. does not allocate), and O(n) worst-case. This function is also known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided comparator function.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2]; // Find the median as if the slice were sorted in descending order. v.select_nth_unstable_by(2, |a, b| b.cmp(a)); // We are only guaranteed the slice will be one of the following, based on the way we sort // about the specified index. assert!(v == [2, 4, 1, -5, -3] || v == [2, 4, 1, -3, -5] || v == [4, 2, 1, -5, -3] || v == [4, 2, 1, -3, -5]);
Reorder the slice with a key extraction function such that the element at index
is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be less than or equal to any value at a position j > index
using the key extraction function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index
), in-place (i.e. does not allocate), and O(n) worst-case. This function is also known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided key extraction function.
Current implementation
The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable
.
Panics
Panics when index >= len()
, meaning it always panics on empty slices.
Examples
let mut v = [-5i32, 4, 1, -3, 2]; // Return the median as if the array were sorted according to absolute value. v.select_nth_unstable_by_key(2, |a| a.abs()); // We are only guaranteed the slice will be one of the following, based on the way we sort // about the specified index. assert!(v == [1, 2, -3, 4, -5] || v == [1, 2, -3, -5, 4] || v == [2, 1, -3, 4, -5] || v == [2, 1, -3, -5, 4]);
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]);
pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T]) where
F: FnMut(&mut T, &mut T) -> bool,
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"]);
pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T]) where
F: FnMut(&mut T) -> K,
K: PartialEq<K>,
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]);
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']);
pub fn rotate_right(&mut self, k: usize)
Rotates the slice in-place such that the first self.len() - k
elements of the slice move to the end while the last k
elements move to the front. After calling rotate_right
, the element previously at index self.len() - k
will become the first element in the slice.
Panics
This function will panic if k
is greater than the length of the slice. Note that k == self.len()
does not panic and is a no-op rotation.
Complexity
Takes linear (in self.len()
) time.
Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; a.rotate_right(2); assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
Rotate a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; a[1..5].rotate_right(1); assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
Fills self
with elements by cloning value
.
Examples
let mut buf = vec![0; 10]; buf.fill(1); assert_eq!(buf, vec![1; 10]);
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]);
Copies the elements from src
into self
.
The length of src
must be the same as self
.
If T
implements Copy
, it can be more performant to use copy_from_slice
.
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]);
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]);
pub fn copy_within<R>(&mut self, src: R, dest: usize) where
T: Copy,
R: RangeBounds<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!");
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]);
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The method may make the middle slice the greatest length possible for a given type and input slice, but only your algorithm’s performance should depend on that, not its correctness. It is permissible for all of the input data to be returned as the prefix or suffix slice.
This method has no purpose when either input element T
or output element U
are zero-sized and will return the original slice without splitting anything.
Safety
This method is essentially a transmute
with respect to the elements in the returned middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
Examples
Basic usage:
unsafe { let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7]; let (prefix, shorts, suffix) = bytes.align_to::<u16>(); // less_efficient_algorithm_for_bytes(prefix); // more_efficient_algorithm_for_aligned_shorts(shorts); // less_efficient_algorithm_for_bytes(suffix); }
pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The method may make the middle slice the greatest length possible for a given type and input slice, but only your algorithm’s performance should depend on that, not its correctness. It is permissible for all of the input data to be returned as the prefix or suffix slice.
This method has no purpose when either input element T
or output element U
are zero-sized and will return the original slice without splitting anything.
Safety
This method is essentially a transmute
with respect to the elements in the returned middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
Examples
Basic usage:
unsafe { let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7]; let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>(); // less_efficient_algorithm_for_bytes(prefix); // more_efficient_algorithm_for_aligned_shorts(shorts); // less_efficient_algorithm_for_bytes(suffix); }
pub fn is_sorted(&self) -> bool where
T: PartialOrd<T>,
is_sorted
#53485)new API
Checks if the elements of this slice are sorted.
That is, for each element a
and its following element b
, a <= b
must hold. If the slice yields exactly zero or one element, true
is returned.
Note that if Self::Item
is only PartialOrd
, but not Ord
, the above definition implies that this function returns false
if any two consecutive items are not comparable.
Examples
#![feature(is_sorted)] let empty: [i32; 0] = []; assert!([1, 2, 2, 9].is_sorted()); assert!(![1, 3, 2, 4].is_sorted()); assert!([0].is_sorted()); assert!(empty.is_sorted()); assert!(![0.0, 1.0, f32::NAN].is_sorted());
is_sorted
#53485)new API
Checks if the elements of this slice are sorted using the given comparator function.
Instead of using PartialOrd::partial_cmp
, this function uses the given compare
function to determine the ordering of two elements. Apart from that, it’s equivalent to is_sorted
; see its documentation for more information.
pub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
F: FnMut(&T) -> K,
K: PartialOrd<K>,
is_sorted
#53485)new API
Checks if the elements of this slice are sorted using the given key extraction function.
Instead of comparing the slice’s elements directly, this function compares the keys of the elements, as determined by f
. Apart from that, it’s equivalent to is_sorted
; see its documentation for more information.
Examples
#![feature(is_sorted)] assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len())); assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).
The slice is assumed to be partitioned according to the given predicate. This means that all elements for which the predicate returns true are at the start of the slice and all elements for which the predicate returns false are at the end. For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0 (all odd numbers are at the start, all even at the end).
If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.
See also binary_search
, binary_search_by
, and binary_search_by_key
.
Examples
let v = [1, 2, 3, 3, 5, 6, 7]; let i = v.partition_point(|&x| x < 5); assert_eq!(i, 4); assert!(v[..i].iter().all(|&x| x < 5)); assert!(v[i..].iter().all(|&x| !(x < 5)));
impl [u8]
pub fn is_ascii(&self) -> bool
Checks if all bytes in this slice are within the ASCII range.
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.
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
.
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
.
pub fn escape_ascii(&self) -> EscapeAscii<'_>
impl<'a> Iterator for EscapeAscii<'a> type Item = u8;
Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.
Examples
#![feature(inherent_ascii_escape)] let s = b"0\t\r\n'\"\\\x9d"; let escaped = s.escape_ascii().to_string(); assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
impl<T> [T]
Sorts the slice.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a non-allocating insertion sort is used instead.
Examples
let mut v = [-5, 4, 1, -3, 2]; v.sort(); assert!(v == [-5, -3, 1, 2, 4]);
Sorts the slice with a comparator function.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified. An order is a total order if it is (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0]; floats.sort_by(|a, b| a.partial_cmp(b).unwrap()); assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable_by
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a non-allocating insertion sort is used instead.
Examples
let mut v = [5, 4, 1, 3, 2]; v.sort_by(|a, b| a.cmp(b)); assert!(v == [1, 2, 3, 4, 5]); // reverse sorting v.sort_by(|a, b| b.cmp(a)); assert!(v == [5, 4, 3, 2, 1]);
Sorts the slice with a key extraction function.
This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).
For expensive key functions (e.g. functions that are not simple property accesses or basic operations), sort_by_cached_key
is likely to be significantly faster, as it does not recompute element keys.
When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable_by_key
.
Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a non-allocating insertion sort is used instead.
Examples
let mut v = [-5i32, 4, 1, -3, 2]; v.sort_by_key(|k| k.abs()); assert!(v == [1, 2, -3, 4, -5]);
Sorts the slice with a key extraction function.
During sorting, the key function is called only once per element.
This sort is stable (i.e., does not reorder equal elements) and O(m * n + n * log(n)) worst-case, where the key function is O(m).
For simple key functions (e.g., functions that are property accesses or basic operations), sort_by_key
is likely to be faster.
Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
In the worst case, the algorithm allocates temporary storage in a Vec<(K, usize)>
the length of the slice.
Examples
let mut v = [-5i32, 4, 32, -3, 2]; v.sort_by_cached_key(|k| k.to_string()); assert!(v == [-3, -5, 2, 32, 4]);
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.
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.
Converts self
into a vector without clones or allocation.
The resulting vector can be converted back into a box via Vec<T>
’s into_boxed_slice
method.
Examples
let s: Box<[i32]> = Box::new([10, 40, 30]); let x = s.into_vec(); // `s` cannot be used anymore because it has been converted into `x`. assert_eq!(x, vec![10, 40, 30]);
Creates a vector by repeating a slice n
times.
Panics
This function will panic if the capacity would overflow.
Examples
Basic usage:
assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);
A panic upon overflow:
// this will panic at runtime b"0123456789abcdef".repeat(usize::MAX);
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]);
pub fn join<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::Output where
[T]: Join<Separator>,
Flattens a slice of T
into a single value Self::Output
, placing a given separator between each.
Examples
assert_eq!(["hello", "world"].join(" "), "hello world"); assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]); assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);
pub fn connect<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::Output where
[T]: Join<Separator>,
renamed to join
Flattens a slice of T
into a single value Self::Output
, placing a given separator between each.
Examples
assert_eq!(["hello", "world"].connect(" "), "hello world"); assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);
impl [u8]
pub fn to_ascii_uppercase(&self) -> Vec<u8, Global>
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
.
pub fn to_ascii_lowercase(&self) -> Vec<u8, Global>
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
impl<T> AsMut<[T]> for [T]
pub fn as_mut(&mut self) -> &mut [T]
Performs the conversion.
impl<T> AsRef<[T]> for [T]
pub fn as_ref(&self) -> &[T]
Performs the conversion.
impl AsciiExt for [u8]
type Owned = Vec<u8>
use inherent methods instead
Container type for copied ASCII characters.
fn is_ascii(&self) -> bool
use inherent methods instead
Checks if the value is within the ASCII range. Read more
fn to_ascii_uppercase(&self) -> Self::Owned
use inherent methods instead
Makes a copy of the value in its ASCII upper case equivalent. Read more
fn to_ascii_lowercase(&self) -> Self::Owned
use inherent methods instead
Makes a copy of the value in its ASCII lower case equivalent. Read more
fn eq_ignore_ascii_case(&self, o: &Self) -> bool
use inherent methods instead
Checks that two values are an ASCII case-insensitive match. Read more
fn make_ascii_uppercase(&mut self)
use inherent methods instead
Converts this type to its ASCII upper case equivalent in-place. Read more
fn make_ascii_lowercase(&mut self)
use inherent methods instead
Converts this type to its ASCII lower case equivalent in-place. Read more
impl BufRead for &[u8]
fn fill_buf(&mut self) -> Result<&[u8]>
Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
fn consume(&mut self, amt: usize)
Tells this buffer that amt
bytes have been consumed from the buffer, so they should no longer be returned in calls to read
. Read more
fn has_data_left(&mut self) -> Result<bool>
buf_read_has_data_left
#86423)recently added
Check if the underlying Read
has any data left to be read. Read more
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>
Read all bytes into buf
until the delimiter byte
or EOF is reached. Read more
fn read_line(&mut self, buf: &mut String) -> Result<usize>
Read all bytes until a newline (the 0xA
byte) is reached, and append them to the provided buffer. Read more
impl<B: BufRead> Iterator for Split<B> type Item = Result<Vec<u8>>;
Returns an iterator over the contents of this reader split on the byte byte
. Read more
impl<B: BufRead> Iterator for Lines<B> type Item = Result<String>;
Returns an iterator over the lines of this reader. Read more
type Output = Vec<T, Global>
The resulting type after concatenation
pub fn concat(slice: &[V]) -> Vec<T, Global>
Implementation of [T]::concat
Note: str
in Concat<str>
is not meaningful here. This type parameter of the trait only exists to enable another impl.
type Output = String
The resulting type after concatenation
pub fn concat(slice: &[S]) -> String
Implementation of [T]::concat
pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
Formats the value using the given formatter. Read more
pub fn default() -> &'_ [T]
Creates an empty slice.
pub fn default() -> &'_ mut [T]
Creates a mutable empty slice.
impl<T, I> Index<I> for [T] where
I: SliceIndex<[T]>,
type Output = <I as SliceIndex<[T]>>::Output
The returned type after indexing.
pub fn index(&self, index: I) -> &<I as SliceIndex<[T]>>::Output
Performs the indexing (container[index]
) operation. Read more
impl<T, I> IndexMut<I> for [T] where
I: SliceIndex<[T]>,
pub fn index_mut(&mut self, index: I) -> &mut <I as SliceIndex<[T]>>::Output
Performs the mutable indexing (container[index]
) operation. Read more
impl<'a, T> IntoIterator for &'a [T]
type Item = &'a T
The type of the elements being iterated over.
type IntoIter = Iter<'a, T>
Which kind of iterator are we turning this into?
pub fn into_iter(self) -> Iter<'a, T>
impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;
Creates an iterator from a value. Read more
impl<'a, T> IntoIterator for &'a mut [T]
type Item = &'a mut T
The type of the elements being iterated over.
type IntoIter = IterMut<'a, T>
Which kind of iterator are we turning this into?
pub fn into_iter(self) -> IterMut<'a, T>
impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;
Creates an iterator from a value. Read more
type Output = Vec<T, Global>
The resulting type after concatenation
pub fn join(slice: &[V], sep: &[T]) -> Vec<T, Global>
Implementation of [T]::join
type Output = Vec<T, Global>
The resulting type after concatenation
pub fn join(slice: &[V], sep: &T) -> Vec<T, Global>
Implementation of [T]::join
type Output = String
The resulting type after concatenation
pub fn join(slice: &[S], sep: &str) -> String
Implementation of [T]::join
Implements comparison of vectors lexicographically.
pub fn cmp(&self, other: &[T]) -> Ordering
fn max(self, other: Self) -> Self
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
Compares and returns the minimum of two values. Read more
fn clamp(self, min: Self, max: Self) -> Self
Restrict a value to a certain interval. Read more
pub fn eq(&self, other: &[A; N]) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &[A; N]) -> bool
This method tests for !=
.
pub fn eq(&self, other: &[A; N]) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &[A; N]) -> bool
This method tests for !=
.
pub fn eq(&self, other: &[A; N]) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &[A; N]) -> bool
This method tests for !=
.
pub fn eq(&self, other: &[B]) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &[B]) -> bool
This method tests for !=
.
pub fn eq(&self, other: &Vec<U, A>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &Vec<U, A>) -> bool
This method tests for !=
.
pub fn eq(&self, other: &Vec<U, A>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &Vec<U, A>) -> bool
This method tests for !=
.
pub fn eq(&self, other: &Vec<U, A>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
pub fn ne(&self, other: &Vec<U, A>) -> bool
This method tests for !=
.
impl<T> PartialOrd<[T]> for [T] where
T: PartialOrd<T>,
Implements comparison of vectors lexicographically.
pub fn partial_cmp(&self, other: &[T]) -> Option<Ordering>
This method returns an ordering between self
and other
values if one exists. Read more
fn lt(&self, other: &Rhs) -> bool
This method tests less than (for self
and other
) and is used by the <
operator. Read more
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
fn gt(&self, other: &Rhs) -> bool
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
fn ge(&self, other: &Rhs) -> bool
This method tests greater than or equal to (for self
and other
) and is used by the >=
operator. Read more
impl<'a, 'b> Pattern<'a> for &'b [char]
Searches for chars that are equal to any of the char
s in the slice.
Examples
assert_eq!("Hello world".find(&['l', 'l'] as &[_]), Some(2)); assert_eq!("Hello world".find(&['l', 'l'][..]), Some(2));
type Searcher = CharSliceSearcher<'a, 'b>
pattern
#27721)API not fully fleshed out and ready to be stabilized
Associated searcher for this pattern
pub fn into_searcher(self, haystack: &'a str) -> CharSliceSearcher<'a, 'b>
pattern
#27721)API not fully fleshed out and ready to be stabilized
Constructs the associated searcher from self
and the haystack
to search in. Read more
pub fn is_contained_in(self, haystack: &'a str) -> bool
pattern
#27721)API not fully fleshed out and ready to be stabilized
Checks whether the pattern matches anywhere in the haystack
pub fn is_prefix_of(self, haystack: &'a str) -> bool
pattern
#27721)API not fully fleshed out and ready to be stabilized
Checks whether the pattern matches at the front of the haystack
pub fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
pattern
#27721)API not fully fleshed out and ready to be stabilized
Removes the pattern from the front of haystack, if it matches.
pub fn is_suffix_of(self, haystack: &'a str) -> bool where
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
pattern
#27721)API not fully fleshed out and ready to be stabilized
Checks whether the pattern matches at the back of the haystack
pub fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str> where
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
pattern
#27721)API not fully fleshed out and ready to be stabilized
Removes the pattern from the back of haystack, if it matches.
impl Read for &[u8]
Read is implemented for &[u8]
by copying from the slice.
Note that reading updates the slice to point to the yet unread part. The slice will be empty when EOF is reached.
fn read(&mut self, buf: &mut [u8]) -> Result<usize>
Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>
Like read
, except that it reads into a slice of buffers. Read more
fn is_read_vectored(&self) -> bool
Determines if this Read
er has an efficient read_vectored
implementation. Read more
unsafe fn initializer(&self) -> Initializer
Determines if this Read
er can work with buffers of uninitialized memory. Read more
fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>
Read the exact number of bytes required to fill buf
. Read more
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>
Read all bytes until EOF in this source, placing them into buf
. Read more
fn read_to_string(&mut self, buf: &mut String) -> Result<usize>
Read all bytes until EOF in this source, appending them to buf
. Read more
Creates a “by reference” adapter for this instance of Read
. Read more
impl<R: Read> Iterator for Bytes<R> type Item = Result<u8>;
impl<T: Read, U: Read> Read for Chain<T, U>
Creates an adapter which will chain this stream with another. Read more
impl<T: Read> Read for Take<T>
Creates an adapter which will read at most limit
bytes from it. Read more
impl<T> SlicePattern for [T]
type Item = T
slice_pattern
#56345)stopgap trait for slice patterns
The element type of the slice being matched on.
pub fn as_slice(&self) -> &[<[T] as SlicePattern>::Item]
slice_pattern
#56345)stopgap trait for slice patterns
Currently, the consumers of SlicePattern
need a slice.
type Owned = Vec<T, Global>
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> Vec<T, Global>
Creates owned data from borrowed data, usually by cloning. Read more
pub fn clone_into(&self, target: &mut Vec<T, Global>)
toowned_clone_into
#41263)recently added
Uses borrowed data to replace owned data, usually by cloning. Read more
impl<'a> ToSocketAddrs for &'a [SocketAddr]
type Iter = Cloned<Iter<'a, SocketAddr>>
Returned iterator over socket addresses which this type may correspond to. Read more
fn to_socket_addrs(&self) -> Result<Self::Iter>
Converts this object to an iterator of resolved SocketAddr
s. Read more
impl Write for &mut [u8]
Write is implemented for &mut [u8]
by copying into the slice, overwriting its data.
Note that writing updates the slice to point to the yet unwritten part. The slice will be empty when it has been completely overwritten.
If the number of bytes to be written exceeds the size of the slice, write operations will return short writes: ultimately, Ok(0)
; in this situation, write_all
returns an error of kind ErrorKind::WriteZero
.
fn write(&mut self, data: &[u8]) -> Result<usize>
Write a buffer into this writer, returning how many bytes were written. Read more
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>
fn is_write_vectored(&self) -> bool
Determines if this Write
r has an efficient write_vectored
implementation. Read more
fn write_all(&mut self, data: &[u8]) -> Result<()>
Attempts to write an entire buffer into this writer. Read more
fn flush(&mut self) -> Result<()>
Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>
Attempts to write multiple buffers into this writer. Read more
fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>
Writes a formatted string into this writer, returning any error encountered. Read more
Creates a “by reference” adapter for this instance of Write
. Read more
Auto Trait Implementations
impl<T> RefUnwindSafe for [T] where
T: RefUnwindSafe,
impl RefUnwindSafe for [u8]
impl<T> Send for [T] where
T: Send,
impl Send for [u8]
impl<T> !Sized for [T]
impl !Sized for [u8]
impl<T> Sync for [T] where
T: Sync,
impl Sync for [u8]
impl<T> Unpin for [T] where
T: Unpin,
impl Unpin for [u8]
impl<T> UnwindSafe for [T] where
T: UnwindSafe,
impl UnwindSafe for [u8]
Blanket Implementations
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/primitive.slice.html