Struct bytes::BytesMut

pub struct BytesMut { /* fields omitted */ }

A unique reference to a contiguous slice of memory.

BytesMut represents a unique view into a potentially shared memory region. Given the uniqueness guarantee, owners of BytesMut handles are able to mutate the memory.

BytesMut can be thought of as containing a buf: Arc<Vec<u8>>, an offset into buf, a slice length, and a guarantee that no other BytesMut for the same buf overlaps with its slice. That guarantee means that a write lock is not required.

Growth

BytesMut’s BufMut implementation will implicitly grow its buffer as necessary. However, explicitly reserving the required space up-front before a series of inserts will be more efficient.

Examples

use bytes::{BytesMut, BufMut};

let mut buf = BytesMut::with_capacity(64);

buf.put_u8(b'h');
buf.put_u8(b'e');
buf.put(&b"llo"[..]);

assert_eq!(&buf[..], b"hello");

// Freeze the buffer so that it can be shared
let a = buf.freeze();

// This does not allocate, instead `b` points to the same memory.
let b = a.clone();

assert_eq!(&a[..], b"hello");
assert_eq!(&b[..], b"hello");

Implementations

impl BytesMut

pub fn with_capacity(capacity: usize) -> BytesMut

Creates a new BytesMut with the specified capacity.

The returned BytesMut will be able to hold at least capacity bytes without reallocating.

It is important to note that this function does not specify the length of the returned BytesMut, but only the capacity.

Examples

use bytes::{BytesMut, BufMut};

let mut bytes = BytesMut::with_capacity(64);

// `bytes` contains no data, even though there is capacity
assert_eq!(bytes.len(), 0);

bytes.put(&b"hello world"[..]);

assert_eq!(&bytes[..], b"hello world");

pub fn new() -> BytesMut

Creates a new BytesMut with default capacity.

Resulting object has length 0 and unspecified capacity. This function does not allocate.

Examples

use bytes::{BytesMut, BufMut};

let mut bytes = BytesMut::new();

assert_eq!(0, bytes.len());

bytes.reserve(2);
bytes.put_slice(b"xy");

assert_eq!(&b"xy"[..], &bytes[..]);

pub fn len(&self) -> usize

Returns the number of bytes contained in this BytesMut.

Examples

use bytes::BytesMut;

let b = BytesMut::from(&b"hello"[..]);
assert_eq!(b.len(), 5);

pub fn is_empty(&self) -> bool

Returns true if the BytesMut has a length of 0.

Examples

use bytes::BytesMut;

let b = BytesMut::with_capacity(64);
assert!(b.is_empty());

pub fn capacity(&self) -> usize

Returns the number of bytes the BytesMut can hold without reallocating.

Examples

use bytes::BytesMut;

let b = BytesMut::with_capacity(64);
assert_eq!(b.capacity(), 64);

pub fn freeze(self) -> Bytes

Converts self into an immutable Bytes.

The conversion is zero cost and is used to indicate that the slice referenced by the handle will no longer be mutated. Once the conversion is done, the handle can be cloned and shared across threads.

Examples

use bytes::{BytesMut, BufMut};
use std::thread;

let mut b = BytesMut::with_capacity(64);
b.put(&b"hello world"[..]);
let b1 = b.freeze();
let b2 = b1.clone();

let th = thread::spawn(move || {
    assert_eq!(&b1[..], b"hello world");
});

assert_eq!(&b2[..], b"hello world");
th.join().unwrap();

#[must_use = "consider BytesMut::truncate if you don't need the other half"]pub fn split_off(&mut self, at: usize) -> BytesMut

Splits the bytes into two at the given index.

Afterwards self contains elements [0, at), and the returned BytesMut contains elements [at, capacity).

This is an O(1) operation that just increases the reference count and sets a few indices.

Examples

use bytes::BytesMut;

let mut a = BytesMut::from(&b"hello world"[..]);
let mut b = a.split_off(5);

a[0] = b'j';
b[0] = b'!';

assert_eq!(&a[..], b"jello");
assert_eq!(&b[..], b"!world");

Panics

Panics if at > capacity.

#[must_use = "consider BytesMut::advance(len()) if you don't need the other half"]pub fn split(&mut self) -> BytesMut

Removes the bytes from the current view, returning them in a new BytesMut handle.

Afterwards, self will be empty, but will retain any additional capacity that it had before the operation. This is identical to self.split_to(self.len()).

This is an O(1) operation that just increases the reference count and sets a few indices.

Examples

use bytes::{BytesMut, BufMut};

let mut buf = BytesMut::with_capacity(1024);
buf.put(&b"hello world"[..]);

let other = buf.split();

assert!(buf.is_empty());
assert_eq!(1013, buf.capacity());

assert_eq!(other, b"hello world"[..]);

#[must_use = "consider BytesMut::advance if you don't need the other half"]pub fn split_to(&mut self, at: usize) -> BytesMut

Splits the buffer into two at the given index.

Afterwards self contains elements [at, len), and the returned BytesMut contains elements [0, at).

This is an O(1) operation that just increases the reference count and sets a few indices.

Examples

use bytes::BytesMut;

let mut a = BytesMut::from(&b"hello world"[..]);
let mut b = a.split_to(5);

a[0] = b'!';
b[0] = b'j';

assert_eq!(&a[..], b"!world");
assert_eq!(&b[..], b"jello");

Panics

Panics if at > len.

pub fn truncate(&mut self, len: usize)

Shortens the buffer, keeping the first len bytes and dropping the rest.

If len is greater than the buffer’s current length, this has no effect.

The split_off method can emulate truncate, but this causes the excess bytes to be returned instead of dropped.

Examples

use bytes::BytesMut;

let mut buf = BytesMut::from(&b"hello world"[..]);
buf.truncate(5);
assert_eq!(buf, b"hello"[..]);

pub fn clear(&mut self)

Clears the buffer, removing all data.

Examples

use bytes::BytesMut;

let mut buf = BytesMut::from(&b"hello world"[..]);
buf.clear();
assert!(buf.is_empty());

pub fn resize(&mut self, new_len: usize, value: u8)

Resizes the buffer so that len is equal to new_len.

If new_len is greater than len, the buffer is extended by the difference with each additional byte set to value. If new_len is less than len, the buffer is simply truncated.

Examples

use bytes::BytesMut;

let mut buf = BytesMut::new();

buf.resize(3, 0x1);
assert_eq!(&buf[..], &[0x1, 0x1, 0x1]);

buf.resize(2, 0x2);
assert_eq!(&buf[..], &[0x1, 0x1]);

buf.resize(4, 0x3);
assert_eq!(&buf[..], &[0x1, 0x1, 0x3, 0x3]);

pub unsafe fn set_len(&mut self, len: usize)

Sets the length of the buffer.

This will explicitly set the size of the buffer without actually modifying the data, so it is up to the caller to ensure that the data has been initialized.

Examples

use bytes::BytesMut;

let mut b = BytesMut::from(&b"hello world"[..]);

unsafe {
    b.set_len(5);
}

assert_eq!(&b[..], b"hello");

unsafe {
    b.set_len(11);
}

assert_eq!(&b[..], b"hello world");

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more bytes to be inserted into the given BytesMut.

More than additional bytes may be reserved in order to avoid frequent reallocations. A call to reserve may result in an allocation.

Before allocating new buffer space, the function will attempt to reclaim space in the existing buffer. If the current handle references a small view in the original buffer and all other handles have been dropped, and the requested capacity is less than or equal to the existing buffer’s capacity, then the current view will be copied to the front of the buffer and the handle will take ownership of the full buffer.

Examples

In the following example, a new buffer is allocated.

use bytes::BytesMut;

let mut buf = BytesMut::from(&b"hello"[..]);
buf.reserve(64);
assert!(buf.capacity() >= 69);

In the following example, the existing buffer is reclaimed.

use bytes::{BytesMut, BufMut};

let mut buf = BytesMut::with_capacity(128);
buf.put(&[0; 64][..]);

let ptr = buf.as_ptr();
let other = buf.split();

assert!(buf.is_empty());
assert_eq!(buf.capacity(), 64);

drop(other);
buf.reserve(128);

assert_eq!(buf.capacity(), 128);
assert_eq!(buf.as_ptr(), ptr);

Panics

Panics if the new capacity overflows usize.

pub fn extend_from_slice(&mut self, extend: &[u8])

Appends given bytes to this BytesMut.

If this BytesMut object does not have enough capacity, it is resized first.

Examples

use bytes::BytesMut;

let mut buf = BytesMut::with_capacity(0);
buf.extend_from_slice(b"aaabbb");
buf.extend_from_slice(b"cccddd");

assert_eq!(b"aaabbbcccddd", &buf[..]);

pub fn unsplit(&mut self, other: BytesMut)

Absorbs a BytesMut that was previously split off.

If the two BytesMut objects were previously contiguous, i.e., if other was created by calling split_off on this BytesMut, then this is an O(1) operation that just decreases a reference count and sets a few indices. Otherwise this method degenerates to self.extend_from_slice(other.as_ref()).

Examples

use bytes::BytesMut;

let mut buf = BytesMut::with_capacity(64);
buf.extend_from_slice(b"aaabbbcccddd");

let split = buf.split_off(6);
assert_eq!(b"aaabbb", &buf[..]);
assert_eq!(b"cccddd", &split[..]);

buf.unsplit(split);
assert_eq!(b"aaabbbcccddd", &buf[..]);

Methods from Deref<Target = [u8]>

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 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());

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]);

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]);
}

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]);

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]);
}

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]);

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());

pub fn last_mut(&mut self) -> Option<&mut T>

Returns a mutable pointer to the last item in the slice.

Examples

let x = &mut [0, 1, 2];

if let Some(last) = x.last_mut() {
    *last = 10;
}
assert_eq!(x, &[0, 1, 10]);

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));
    }
}

pub const fn as_mut_ptr(&mut self) -> *mut T

Returns an unsafe mutable pointer to the slice’s buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

Examples

let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();

unsafe {
    for i in 0..x.len() {
        *x_ptr.add(i) += 2;
    }
}
assert_eq!(x, &[3, 4, 6]);

pub const 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));

pub const 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++.

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>

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>

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>

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>

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>

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>

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>

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]]

🔬 This is a nightly-only experimental API. (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 (aka self.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])

🔬 This is a nightly-only experimental API. (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']);

pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])

🔬 This is a nightly-only experimental API. (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']]);

pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>

🔬 This is a nightly-only experimental API. (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']);

pub unsafe fn as_chunks_unchecked_mut<const N: usize>(
    &mut self
) -> &mut [[T; N]]

🔬 This is a nightly-only experimental API. (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 (aka self.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])

🔬 This is a nightly-only experimental API. (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]);

pub fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]])

🔬 This is a nightly-only experimental API. (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]);

pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>

🔬 This is a nightly-only experimental API. (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]);

pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>

🔬 This is a nightly-only experimental API. (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());

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());

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]);

pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks.

See rchunks for a variant of this iterator that also returns the remainder as a smaller chunk, and chunks_exact for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is 0.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);

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]);

pub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
    F: FnMut(&T, &T) -> bool, 

🔬 This is a nightly-only experimental API. (slice_group_by)

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);

pub fn group_by_mut<F>(&mut self, pred: F) -> GroupByMut<'_, T, F> where
    F: FnMut(&T, &T) -> bool, 

🔬 This is a nightly-only experimental API. (slice_group_by)

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]);

pub fn split<F>(&self, pred: F) -> Split<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred. The matched element is not contained in the subslices.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:

let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());

If two matched elements are directly adjacent, an empty slice will be present between them:

let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over mutable subslices separated by elements that match pred. The matched element is not contained in the subslices.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.split_mut(|num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 1]);

pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred. The matched element is contained in the end of the previous subslice as a terminator.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.

let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());

pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over mutable subslices separated by elements that match pred. The matched element is contained in the previous subslice as a terminator.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
    let terminator_idx = group.len()-1;
    group[terminator_idx] = 1;
}
assert_eq!(v, [10, 40, 1, 20, 1, 1]);

pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

Examples

let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);

assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);

As with split(), if the first or last element is matched, an empty slice will be the first (or last) item returned by the iterator.

let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);

pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over mutable subslices separated by elements that match pred, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

Examples

let mut v = [100, 400, 300, 200, 600, 500];

let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
    count += 1;
    group[0] = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);

pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred, limited to returning at most n items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once by numbers divisible by 3 (i.e., [10, 40], [20, 60, 50]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.splitn(2, |num| *num % 3 == 0) {
    println!("{:?}", group);
}

pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred, limited to returning at most n items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.splitn_mut(2, |num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);

pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred limited to returning at most n items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once, starting from the end, by numbers divisible by 3 (i.e., [50], [10, 40, 30, 20]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.rsplitn(2, |num| *num % 3 == 0) {
    println!("{:?}", group);
}

pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F> where
    F: FnMut(&T) -> bool, 

Returns an iterator over subslices separated by elements that match pred limited to returning at most n items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

let mut s = [10, 40, 30, 20, 60, 50];

for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);

pub fn contains(&self, x: &T) -> bool where
    T: PartialEq<T>, 

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 an &T, but just an &U such that T: Borrow<U> (e.g. String: Borrow<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"));

pub fn starts_with(&self, needle: &[T]) -> bool where
    T: PartialEq<T>, 

Returns true if needle is a prefix of the slice.

Examples

let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));

pub fn ends_with(&self, needle: &[T]) -> bool where
    T: PartialEq<T>, 

Returns true if needle is a suffix of the slice.

Examples

let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));

#[must_use = "returns the subslice without modifying the original"]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()));

#[must_use = "returns the subslice without modifying the original"]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);

pub fn binary_search(&self, x: &T) -> Result<usize, usize> where
    T: Ord, 

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. 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]);

pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize> where
    F: FnMut(&'a T) -> Ordering, 

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. 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, });

pub fn binary_search_by_key<'a, B, F>(
    &'a self,
    b: &B,
    f: F
) -> Result<usize, usize> where
    B: Ord,
    F: FnMut(&'a T) -> B, 

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. 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, });

pub fn sort_unstable(&mut self) where
    T: Ord, 

Sorts the slice, but may 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]);

pub fn sort_unstable_by<F>(&mut self, compare: F) where
    F: FnMut(&T, &T) -> Ordering, 

Sorts the slice with a comparator function, but may 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 or a > b is true, and
• transitive, a < b and b < c implies a < 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]);

pub fn sort_unstable_by_key<K, F>(&mut self, f: F) where
    F: FnMut(&T) -> K,
    K: Ord, 

Sorts the slice with a key extraction function, but may 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, 

👎 Deprecated since 1.49.0:

use the select_nth_unstable() instead

🔬 This is a nightly-only experimental API. (slice_partition_at_index)

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, 

👎 Deprecated since 1.49.0:

use select_nth_unstable_by() instead

🔬 This is a nightly-only experimental API. (slice_partition_at_index)

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, 

👎 Deprecated since 1.49.0:

use the select_nth_unstable_by_key() instead

🔬 This is a nightly-only experimental API. (slice_partition_at_index)

Reorder the slice with a key extraction function such that the element at index is at its final sorted position.

pub fn select_nth_unstable(
    &mut self,
    index: usize
) -> (&mut [T], &mut T, &mut [T]) where
    T: Ord, 

Reorder the slice such that the element at index is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and O(n) worst-case. This function is also/ known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index.

Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

Examples

let mut v = [-5i32, 4, 1, -3, 2];

// Find the median
v.select_nth_unstable(2);

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
        v == [-5, -3, 1, 2, 4] ||
        v == [-3, -5, 1, 4, 2] ||
        v == [-5, -3, 1, 4, 2]);

pub fn select_nth_unstable_by<F>(
    &mut self,
    index: usize,
    compare: F
) -> (&mut [T], &mut T, &mut [T]) where
    F: FnMut(&T, &T) -> Ordering, 

Reorder the slice with a comparator function such that the element at index is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index using the comparator function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and O(n) worst-case. This function is also known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided comparator function.

Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

Examples

let mut v = [-5i32, 4, 1, -3, 2];

// Find the median as if the slice were sorted in descending order.
v.select_nth_unstable_by(2, |a, b| b.cmp(a));

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
        v == [2, 4, 1, -3, -5] ||
        v == [4, 2, 1, -5, -3] ||
        v == [4, 2, 1, -3, -5]);

pub fn select_nth_unstable_by_key<K, F>(
    &mut self,
    index: usize,
    f: F
) -> (&mut [T], &mut T, &mut [T]) where
    F: FnMut(&T) -> K,
    K: Ord, 

Reorder the slice with a key extraction function such that the element at index is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index using the key extraction function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and O(n) worst-case. This function is also known as “kth element” in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided key extraction function.

Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for sort_unstable.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

Examples

let mut v = [-5i32, 4, 1, -3, 2];

// Return the median as if the array were sorted according to absolute value.
v.select_nth_unstable_by_key(2, |a| a.abs());

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
        v == [1, 2, -3, -5, 4] ||
        v == [2, 1, -3, 4, -5] ||
        v == [2, 1, -3, -5, 4]);

pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T]) where
    T: PartialEq<T>, 

🔬 This is a nightly-only experimental API. (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]);

pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T]) where
    F: FnMut(&mut T, &mut T) -> bool, 

🔬 This is a nightly-only experimental API. (slice_partition_dedup)

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>, 

🔬 This is a nightly-only experimental API. (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]);

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']);

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]);

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]);

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.

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]);

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]);

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>, 

🔬 This is a nightly-only experimental API. (is_sorted)

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());

pub fn is_sorted_by<F>(&self, compare: F) -> bool where
    F: FnMut(&T, &T) -> Option<Ordering>, 

🔬 This is a nightly-only experimental API. (is_sorted)

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>, 

🔬 This is a nightly-only experimental API. (is_sorted)

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()));

pub fn partition_point<P>(&self, pred: P) -> usize where
    P: FnMut(&T) -> bool, 

Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).

The slice is assumed to be partitioned according to the given predicate. This means that all elements for which the predicate returns true are at the start of the slice and all elements for which the predicate returns false are at the end. For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0 (all odd numbers are at the start, all even at the end).

If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.

See also binary_search, binary_search_by, and binary_search_by_key.

Examples

let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);

assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));

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 sort(&mut self) where
    T: Ord, 

Sorts the slice.

This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable.

Current implementation

The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.

Also, it allocates temporary storage half the size of self, but for short slices a non-allocating insertion sort is used instead.

Examples

let mut v = [-5, 4, 1, -3, 2];

v.sort();
assert!(v == [-5, -3, 1, 2, 4]);

pub fn sort_by<F>(&mut self, compare: F) where
    F: FnMut(&T, &T) -> Ordering, 

Sorts the slice with a comparator function.

This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.

The comparator function must define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified. An order is a total order if it is (for all a, b and c):

• total and antisymmetric: exactly one of a < b, a == b or a > b is true, and
• transitive, a < b and b < c implies a < 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]);

pub fn sort_by_key<K, F>(&mut self, f: F) where
    F: FnMut(&T) -> K,
    K: Ord, 

Sorts the slice with a key extraction function.

This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).

For expensive key functions (e.g. functions that are not simple property accesses or basic operations), sort_by_cached_key is likely to be significantly faster, as it does not recompute element keys.

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable_by_key.

Current implementation

The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.

Also, it allocates temporary storage half the size of self, but for short slices a non-allocating insertion sort is used instead.

Examples

let mut v = [-5i32, 4, 1, -3, 2];

v.sort_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);

pub fn sort_by_cached_key<K, F>(&mut self, f: F) where
    F: FnMut(&T) -> K,
    K: Ord, 

Sorts the slice with a key extraction function.

During sorting, the key function is called 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]);

pub fn to_vec(&self) -> Vec<T, Global> 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.

pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A> where
    T: Clone,
    A: Allocator, 

🔬 This is a nightly-only experimental API. (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.

pub fn repeat(&self, n: usize) -> Vec<T, Global> where
    T: Copy, 

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);

pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output where
    Item: ?Sized,
    [T]: Concat<Item>, 

Flattens a slice of T into a single value Self::Output.

Examples

assert_eq!(["hello", "world"].concat(), "helloworld");
assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);

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>, 

👎 Deprecated since 1.3.0:

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]);

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 AsMut<[u8]> for BytesMut

fn as_mut(&mut self) -> &mut [u8]

Performs the conversion.

impl AsRef<[u8]> for BytesMut

fn as_ref(&self) -> &[u8]

Performs the conversion.

impl Borrow<[u8]> for BytesMut

fn borrow(&self) -> &[u8]

Immutably borrows from an owned value.

impl BorrowMut<[u8]> for BytesMut

fn borrow_mut(&mut self) -> &mut [u8]

Mutably borrows from an owned value.

impl Buf for BytesMut

fn remaining(&self) -> usize

Returns the number of bytes between the current position and the end of the buffer.

fn bytes(&self) -> &[u8]

Returns a slice starting at the current position and of length between 0 and Buf::remaining(). Note that this can return shorter slice (this allows non-continuous internal representation).

fn advance(&mut self, cnt: usize)

Advance the internal cursor of the Buf

fn to_bytes(&mut self) -> Bytes

Consumes remaining bytes inside self and returns new instance of Bytes

fn bytes_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize

Fills dst with potentially multiple slices starting at self’s current position.

fn has_remaining(&self) -> bool

Returns true if there are any more bytes to consume

fn copy_to_slice(&mut self, dst: &mut [u8])

Copies bytes from self into dst.

fn get_u8(&mut self) -> u8

Gets an unsigned 8 bit integer from self.

fn get_i8(&mut self) -> i8

Gets a signed 8 bit integer from self.

fn get_u16(&mut self) -> u16

Gets an unsigned 16 bit integer from self in big-endian byte order.

fn get_u16_le(&mut self) -> u16

Gets an unsigned 16 bit integer from self in little-endian byte order.

fn get_i16(&mut self) -> i16

Gets a signed 16 bit integer from self in big-endian byte order.

fn get_i16_le(&mut self) -> i16

Gets a signed 16 bit integer from self in little-endian byte order.

fn get_u32(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the big-endian byte order.

fn get_u32_le(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the little-endian byte order.

fn get_i32(&mut self) -> i32

Gets a signed 32 bit integer from self in big-endian byte order.

fn get_i32_le(&mut self) -> i32

Gets a signed 32 bit integer from self in little-endian byte order.

fn get_u64(&mut self) -> u64

Gets an unsigned 64 bit integer from self in big-endian byte order.

fn get_u64_le(&mut self) -> u64

Gets an unsigned 64 bit integer from self in little-endian byte order.

fn get_i64(&mut self) -> i64

Gets a signed 64 bit integer from self in big-endian byte order.

fn get_i64_le(&mut self) -> i64

Gets a signed 64 bit integer from self in little-endian byte order.

fn get_u128(&mut self) -> u128

Gets an unsigned 128 bit integer from self in big-endian byte order.

fn get_u128_le(&mut self) -> u128

Gets an unsigned 128 bit integer from self in little-endian byte order.

fn get_i128(&mut self) -> i128

Gets a signed 128 bit integer from self in big-endian byte order.

fn get_i128_le(&mut self) -> i128

Gets a signed 128 bit integer from self in little-endian byte order.

fn get_uint(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in big-endian byte order.

fn get_uint_le(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in little-endian byte order.

fn get_int(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in big-endian byte order.

fn get_int_le(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in little-endian byte order.

fn get_f32(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in big-endian byte order.

fn get_f32_le(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in little-endian byte order.

fn get_f64(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in big-endian byte order.

fn get_f64_le(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in little-endian byte order.

impl BufMut for BytesMut

fn remaining_mut(&self) -> usize

Returns the number of bytes that can be written from the current position until the end of the buffer is reached.

unsafe fn advance_mut(&mut self, cnt: usize)

Advance the internal cursor of the BufMut

fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>]

Returns a mutable slice starting at the current BufMut position and of length between 0 and BufMut::remaining_mut(). Note that this can be shorter than the whole remainder of the buffer (this allows non-continuous implementation).

fn put<T: Buf>(&mut self, src: T) where
    Self: Sized, 

Transfer bytes into self from src and advance the cursor by the number of bytes written.

fn put_slice(&mut self, src: &[u8])

Transfer bytes into self from src and advance the cursor by the number of bytes written.

fn has_remaining_mut(&self) -> bool

Returns true if there is space in self for more bytes.

fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize

Fills dst with potentially multiple mutable slices starting at self’s current position.

fn put_u8(&mut self, n: u8)

Writes an unsigned 8 bit integer to self.

fn put_i8(&mut self, n: i8)

Writes a signed 8 bit integer to self.

fn put_u16(&mut self, n: u16)

Writes an unsigned 16 bit integer to self in big-endian byte order.

fn put_u16_le(&mut self, n: u16)

Writes an unsigned 16 bit integer to self in little-endian byte order.

fn put_i16(&mut self, n: i16)

Writes a signed 16 bit integer to self in big-endian byte order.

fn put_i16_le(&mut self, n: i16)

Writes a signed 16 bit integer to self in little-endian byte order.

fn put_u32(&mut self, n: u32)

Writes an unsigned 32 bit integer to self in big-endian byte order.

fn put_u32_le(&mut self, n: u32)

Writes an unsigned 32 bit integer to self in little-endian byte order.

fn put_i32(&mut self, n: i32)

Writes a signed 32 bit integer to self in big-endian byte order.

fn put_i32_le(&mut self, n: i32)

Writes a signed 32 bit integer to self in little-endian byte order.

fn put_u64(&mut self, n: u64)

Writes an unsigned 64 bit integer to self in the big-endian byte order.

fn put_u64_le(&mut self, n: u64)

Writes an unsigned 64 bit integer to self in little-endian byte order.

fn put_i64(&mut self, n: i64)

Writes a signed 64 bit integer to self in the big-endian byte order.

fn put_i64_le(&mut self, n: i64)

Writes a signed 64 bit integer to self in little-endian byte order.

fn put_u128(&mut self, n: u128)

Writes an unsigned 128 bit integer to self in the big-endian byte order.

fn put_u128_le(&mut self, n: u128)

Writes an unsigned 128 bit integer to self in little-endian byte order.

fn put_i128(&mut self, n: i128)

Writes a signed 128 bit integer to self in the big-endian byte order.

fn put_i128_le(&mut self, n: i128)

Writes a signed 128 bit integer to self in little-endian byte order.

fn put_uint(&mut self, n: u64, nbytes: usize)

Writes an unsigned n-byte integer to self in big-endian byte order.

fn put_uint_le(&mut self, n: u64, nbytes: usize)

Writes an unsigned n-byte integer to self in the little-endian byte order.

fn put_int(&mut self, n: i64, nbytes: usize)

Writes a signed n-byte integer to self in big-endian byte order.

fn put_int_le(&mut self, n: i64, nbytes: usize)

Writes a signed n-byte integer to self in little-endian byte order.

fn put_f32(&mut self, n: f32)

Writes an IEEE754 single-precision (4 bytes) floating point number to self in big-endian byte order.

fn put_f32_le(&mut self, n: f32)

Writes an IEEE754 single-precision (4 bytes) floating point number to self in little-endian byte order.

fn put_f64(&mut self, n: f64)

Writes an IEEE754 double-precision (8 bytes) floating point number to self in big-endian byte order.

fn put_f64_le(&mut self, n: f64)

Writes an IEEE754 double-precision (8 bytes) floating point number to self in little-endian byte order.

impl Clone for BytesMut

fn clone(&self) -> BytesMut

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BytesMut

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for BytesMut

fn default() -> BytesMut

Returns the “default value” for a type.

impl Deref for BytesMut

type Target = [u8]

The resulting type after dereferencing.

fn deref(&self) -> &[u8]

Dereferences the value.

impl DerefMut for BytesMut

fn deref_mut(&mut self) -> &mut [u8]

Mutably dereferences the value.

impl Drop for BytesMut

fn drop(&mut self)

Executes the destructor for this type.

impl Eq for BytesMut

impl<'a> Extend<&'a u8> for BytesMut

fn extend<T>(&mut self, iter: T) where
    T: IntoIterator<Item = &'a u8>, 

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl Extend<u8> for BytesMut

fn extend<T>(&mut self, iter: T) where
    T: IntoIterator<Item = u8>, 

Extends a collection with the contents of an iterator.

pub fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

pub fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<'a> From<&'a [u8]> for BytesMut

fn from(src: &'a [u8]) -> BytesMut

Performs the conversion.

impl<'a> From<&'a str> for BytesMut

fn from(src: &'a str) -> BytesMut

Performs the conversion.

impl From<BytesMut> for Bytes

fn from(src: BytesMut) -> Bytes

Performs the conversion.

impl<'a> FromIterator<&'a u8> for BytesMut

fn from_iter<T: IntoIterator<Item = &'a u8>>(into_iter: T) -> Self

Creates a value from an iterator.

impl FromIterator<u8> for BytesMut

fn from_iter<T: IntoIterator<Item = u8>>(into_iter: T) -> Self

Creates a value from an iterator.

impl Hash for BytesMut

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given Hasher.

pub fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl IntoIterator for BytesMut

type Item = u8

The type of the elements being iterated over.

type IntoIter = IntoIter<BytesMut>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a> IntoIterator for &'a BytesMut

type Item = &'a u8

The type of the elements being iterated over.

type IntoIter = Iter<'a, u8>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl LowerHex for BytesMut

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Ord for BytesMut

fn cmp(&self, other: &BytesMut) -> Ordering

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<'a, T: ?Sized> PartialEq<&'a T> for BytesMut where
    BytesMut: PartialEq<T>, 

fn eq(&self, other: &&'a T) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<[u8]> for BytesMut

fn eq(&self, other: &[u8]) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Bytes> for BytesMut

fn eq(&self, other: &Bytes) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<BytesMut> for BytesMut

fn eq(&self, other: &BytesMut) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<BytesMut> for [u8]

fn eq(&self, other: &BytesMut) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<BytesMut> for &[u8]

fn eq(&self, other: &BytesMut) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<BytesMut> for Bytes

fn eq(&self, other: &BytesMut) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<String> for BytesMut

fn eq(&self, other: &String) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Vec<u8, Global>> for BytesMut

fn eq(&self, other: &Vec<u8>) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<str> for BytesMut

fn eq(&self, other: &str) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a, T: ?Sized> PartialOrd<&'a T> for BytesMut where
    BytesMut: PartialOrd<T>, 

fn partial_cmp(&self, other: &&'a T) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<[u8]> for BytesMut

fn partial_cmp(&self, other: &[u8]) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<BytesMut> for BytesMut

fn partial_cmp(&self, other: &BytesMut) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<BytesMut> for [u8]

fn partial_cmp(&self, other: &BytesMut) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<BytesMut> for &[u8]

fn partial_cmp(&self, other: &BytesMut) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<String> for BytesMut

fn partial_cmp(&self, other: &String) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<Vec<u8, Global>> for BytesMut

fn partial_cmp(&self, other: &Vec<u8>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd<str> for BytesMut

fn partial_cmp(&self, other: &str) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Send for BytesMut

impl Sync for BytesMut

impl UpperHex for BytesMut

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Write for BytesMut

fn write_str(&mut self, s: &str) -> Result

Writes a string slice into this writer, returning whether the write succeeded.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result

Glue for usage of the write! macro with implementors of this trait.

pub fn write_char(&mut self, c: char) -> Result<(), Error>

Writes a char into this writer, returning whether the write succeeded.