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. It is similar to a Vec<u8> but with less copies and allocations.

For more detail, see Bytes.

Growth

One key difference from Vec<u8> is that most operations do not implicitly grow the buffer. This means that calling my_bytes.put("hello world"); could panic if my_bytes does not have enough capacity. Before writing to the buffer, ensure that there is enough remaining capacity by calling my_bytes.remaining_mut(). In general, avoiding calls to reserve is preferable.

The only exception is extend which implicitly reserves required capacity.

Examples

use bytes::{BytesMut, BufMut};

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

buf.put(b'h');
buf.put(b'e');
buf.put("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");

Methods

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. If capacity is under 4 * size_of::<usize>() - 1, then BytesMut will not allocate.

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("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();

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.

pub fn take(&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.take();

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

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

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 advance(&mut self, cnt: usize)

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

This is the same function as Buf::advance, and in the next breaking release of bytes, this implementation will be removed in favor of having BytesMut implement Buf.

Panics

This function panics if cnt is greater than self.len()

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");

Panics

This method will panic if len is out of bounds for the underlying slice or if it comes after the end of the configured window.

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.take();

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 object.

If this BytesMut object has not enough capacity, it is resized first. So unlike put_slice operation, extend_from_slice does not panic.

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)

Combine splitted BytesMut objects back as contiguous.

If BytesMut objects were not contiguous originally, they will be extended.

Examples

use bytes::BytesMut;

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

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

buf.unsplit(splitted);
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.

This is generally not recommended, use with caution! For a safe alternative see get.

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.

This is generally not recommended, use with caution! For a safe alternative see get_mut.

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.

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.offset(i as isize));
    }
}

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

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

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

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

Examples

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

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

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]);

Important traits for Iter<'a, T>

impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;

pub fn iter(&self) -> Iter<T>

Returns an iterator over the slice.

Examples

let x = &[1, 2, 4];
let mut iterator = x.iter();

assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);

Important traits for IterMut<'a, T>

impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;

pub fn iter_mut(&mut self) -> IterMut<T>

Returns an iterator that allows modifying each value.

Examples

let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
    *elem += 2;
}
assert_eq!(x, &[3, 4, 6]);

Important traits for Windows<'a, T>

impl<'a, T> Iterator for Windows<'a, T> type Item = &'a [T];

pub fn windows(&self, size: usize) -> Windows<T>

Returns an iterator over all contiguous windows of length size. The windows overlap. If the slice is shorter than size, the iterator returns no values.

Panics

Panics if size is 0.

Examples

let slice = ['r', 'u', 's', 't'];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), &['r', 'u']);
assert_eq!(iter.next().unwrap(), &['u', 's']);
assert_eq!(iter.next().unwrap(), &['s', 't']);
assert!(iter.next().is_none());

If the slice is shorter than size:

let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());

Important traits for Chunks<'a, T>

impl<'a, T> Iterator for Chunks<'a, T> type Item = &'a [T];

pub fn chunks(&self, chunk_size: usize) -> Chunks<T>

Returns an iterator over chunk_size elements of the slice at a time. 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 exact_chunks for a variant of this iterator that returns chunks of always exactly chunk_size elements.

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());

Important traits for ChunksMut<'a, T>

impl<'a, T> Iterator for ChunksMut<'a, T> type Item = &'a mut [T];

pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T>

Returns an iterator over chunk_size elements of the slice at a time. 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 exact_chunks_mut for a variant of this iterator that returns chunks of always exactly chunk_size elements.

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]);

Important traits for ExactChunks<'a, T>

impl<'a, T> Iterator for ExactChunks<'a, T> type Item = &'a [T];

pub fn exact_chunks(&self, chunk_size: usize) -> ExactChunks<T>

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

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

Panics

Panics if chunk_size is 0.

Examples

#![feature(exact_chunks)]

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

Important traits for ExactChunksMut<'a, T>

impl<'a, T> Iterator for ExactChunksMut<'a, T> type Item = &'a mut [T];

pub fn exact_chunks_mut(&mut self, chunk_size: usize) -> ExactChunksMut<T>

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

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

Panics

Panics if chunk_size is 0.

Examples

#![feature(exact_chunks)]

let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.exact_chunks_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);

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!(left == []);
   assert!(right == [1, 2, 3, 4, 5, 6]);
}

{
    let (left, right) = v.split_at(2);
    assert!(left == [1, 2]);
    assert!(right == [3, 4, 5, 6]);
}

{
    let (left, right) = v.split_at(6);
    assert!(left == [1, 2, 3, 4, 5, 6]);
    assert!(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];
// scoped to restrict the lifetime of the borrows
{
    let (left, right) = v.split_at_mut(2);
    assert!(left == [1, 0]);
    assert!(right == [3, 0, 5, 6]);
    left[1] = 2;
    right[1] = 4;
}
assert!(v == [1, 2, 3, 4, 5, 6]);

Important traits for Split<'a, T, P>

impl<'a, T, P> Iterator for Split<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a [T];

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());

Important traits for SplitMut<'a, T, P>

impl<'a, T, P> Iterator for SplitMut<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a mut [T];

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]);

Important traits for RSplit<'a, T, P>

impl<'a, T, P> Iterator for RSplit<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a [T];

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);

Important traits for RSplitMut<'a, T, P>

impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a mut [T];

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]);

Important traits for SplitN<'a, T, P>

impl<'a, T, P> Iterator for SplitN<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a [T];

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);
}

Important traits for SplitNMut<'a, T, P>

impl<'a, T, P> Iterator for SplitNMut<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a mut [T];

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]);

Important traits for RSplitN<'a, T, P>

impl<'a, T, P> Iterator for RSplitN<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a [T];

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);
}

Important traits for RSplitNMut<'a, T, P>

impl<'a, T, P> Iterator for RSplitNMut<'a, T, P> where
    P: FnMut(&T) -> bool,  type Item = &'a mut [T];

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));

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(&[]));

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 Ok is returned, containing the index of the matching element; if the value is not found then Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

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, });

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 a matching value is found then returns Ok, containing the index for the matched element; if no match is found then Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

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 a matching value is found then returns Ok, containing the index for the matched element; if no match is found then Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

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.

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(m 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.

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 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 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 src 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 src 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 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])

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

Transmute the slice to a slice of another type, ensuring aligment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle slice will have the greatest length possible for a given type and input 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.

Unsafety

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])

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

Transmute the slice to a slice of another type, ensuring aligment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle slice will have the greatest length possible for a given type and input 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.

Unsafety

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_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.

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(m n)) worst-case, where the key function is O(m).

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,

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

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

#![feature(slice_sort_by_cached_key)]
let mut v = [-5i32, 4, 32, -3, 2];

v.sort_by_cached_key(|k| k.to_string());
assert!(v == [-3, -5, 2, 32, 4]);

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn to_vec(&self) -> Vec<T> where     T: Clone,

Copies self into a new Vec.

Examples

let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.

Important traits for Vec<u8>

impl Write for Vec<u8>

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

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

it's on str, why not on slice?

Creates a vector by repeating a slice n times.

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

#![feature(repeat_generic_slice)]

fn main() {
    assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);
}

A panic upon overflow:

#![feature(repeat_generic_slice)]
fn main() {
    // this will panic at runtime
    b"0123456789abcdef".repeat(usize::max_value());
}

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn to_ascii_uppercase(&self) -> Vec<u8>

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.

ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn to_ascii_lowercase(&self) -> Vec<u8>

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.

ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

Trait Implementations

impl FromBuf for BytesMut

fn from_buf<T>(buf: T) -> Self where     T: IntoBuf,

Creates a value from a buffer.

impl From<BytesMut> for Bytes

fn from(src: BytesMut) -> Bytes

Performs the conversion.

impl FromIterator<u8> for BytesMut

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

Creates a value from an iterator.

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

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Returns a mutable slice starting at the current BufMut position and of length between 0 and BufMut::remaining_mut().

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

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

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 has_remaining_mut(&self) -> bool

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

unsafe fn bytes_vec_mut<'a>(&'a mut self, dst: &mut [&'a mut IoVec]) -> usize

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

fn put<T: IntoBuf>(&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_u16_be(&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_be(&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_be(&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_be(&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_be(&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_be(&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_uint_be(&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_be(&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_be(&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_be(&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.

Important traits for &'a mut W

impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn by_ref(&mut self) -> &mut Self where     Self: Sized,

Creates a "by reference" adaptor for this instance of BufMut.

Important traits for Writer<B>

impl<B: BufMut + Sized> Write for Writer<B>

fn writer(self) -> Writer<Self> where     Self: Sized,

Creates an adaptor which implements the Write trait for self.

impl IntoBuf for BytesMut

type Buf = Cursor<Self>

The Buf type that self is being converted into

fn into_buf(self) -> Self::Buf

Creates a Buf from a value.

impl<'a> IntoBuf for &'a BytesMut

type Buf = Cursor<&'a BytesMut>

The Buf type that self is being converted into

fn into_buf(self) -> Self::Buf

Creates a Buf from a value.

impl AsRef<[u8]> for BytesMut

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Performs the conversion.

impl Deref for BytesMut

type Target = [u8]

The resulting type after dereferencing.

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Dereferences the value.

impl AsMut<[u8]> for BytesMut

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Performs the conversion.

impl DerefMut for BytesMut

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Mutably dereferences the value.

impl From<Vec<u8>> for BytesMut

fn from(src: Vec<u8>) -> BytesMut

Performs the conversion.

impl From<String> for BytesMut

fn from(src: String) -> BytesMut

Performs the conversion.

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<Bytes> for BytesMut

fn from(src: Bytes) -> BytesMut

Performs the conversion.

impl PartialEq 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] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialOrd 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] fn lt(&self, other: &Rhs) -> bool

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

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

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

#[must_use] 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 Ord for BytesMut

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

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl Eq for BytesMut

impl Default for BytesMut

fn default() -> BytesMut

Returns the "default value" for a type.

impl Debug for BytesMut

fn fmt(&self, fmt: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Hash for BytesMut

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

Feeds this value into the given [Hasher].

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

Feeds a slice of this type into the given [Hasher].

impl Borrow<[u8]> for BytesMut

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Immutably borrows from an owned value.

impl BorrowMut<[u8]> for BytesMut

Important traits for &'a mut [u8]

impl<'a> Write for &'a mut [u8]impl<'a> Read for &'a [u8]

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

Mutably borrows from an owned value.

impl Write for BytesMut

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

Writes a slice of bytes 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.

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

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

impl Clone for BytesMut

fn clone(&self) -> BytesMut

Returns a copy of the value.

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

Performs copy-assignment from source.

impl IntoIterator for BytesMut

type Item = u8

The type of the elements being iterated over.

type IntoIter = Iter<Cursor<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 = u8

The type of the elements being iterated over.

type IntoIter = Iter<Cursor<&'a BytesMut>>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

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.

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.

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] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

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] fn lt(&self, other: &Rhs) -> bool

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

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

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

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

This method tests for !=.

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] fn lt(&self, other: &Rhs) -> bool

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

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

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

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

This method tests for !=.

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] fn lt(&self, other: &Rhs) -> bool

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

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

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

#[must_use] 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 PartialEq<BytesMut> for str

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

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

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

This method tests for !=.

impl PartialOrd<BytesMut> for str

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

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

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

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

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

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

#[must_use] 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 PartialEq<Vec<u8>> 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] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialOrd<Vec<u8>> 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] fn lt(&self, other: &Rhs) -> bool

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

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

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

#[must_use] 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 PartialEq<BytesMut> for Vec<u8>

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

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

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

This method tests for !=.

impl PartialOrd<BytesMut> for Vec<u8>

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

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

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

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

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

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

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

This method tests for !=.

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] fn lt(&self, other: &Rhs) -> bool

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

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

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

#[must_use] 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 PartialEq<BytesMut> for String

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

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

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

This method tests for !=.

impl PartialOrd<BytesMut> for String

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

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

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

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

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

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

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

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

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

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

#[must_use] 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<'a> PartialEq<BytesMut> for &'a [u8]

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

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

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

This method tests for !=.

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

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

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

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

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

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

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

#[must_use] 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<'a> PartialEq<BytesMut> for &'a str

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

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

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

This method tests for !=.

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

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

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

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

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

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

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

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

This method tests for !=.