[][src]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
[src]

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");

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[..]);

Returns the number of bytes contained in this BytesMut.

Examples

use bytes::BytesMut;

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

Returns true if the BytesMut has a length of 0.

Examples

use bytes::BytesMut;

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

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);

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();

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.

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"[..]);

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.

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"[..]);

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()

Clears the buffer, removing all data.

Examples

use bytes::BytesMut;

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

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]);

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.

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.

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[..]);

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[..]);

Trait Implementations

impl BufMut for BytesMut
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Returns the number of bytes that can be written from the current position until the end of the buffer is reached. Read more

Advance the internal cursor of the BufMut Read more

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

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

Writes an unsigned 8 bit integer to self. Read more

Writes a signed 8 bit integer to self. Read more

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Important traits for Writer<B>

Creates an adaptor which implements the Write trait for self. Read more

impl FromBuf for BytesMut
[src]

Creates a value from a buffer. Read more

impl IntoBuf for BytesMut
[src]

The Buf type that self is being converted into

Creates a Buf from a value. Read more

impl<'a> IntoBuf for &'a BytesMut
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The Buf type that self is being converted into

Creates a Buf from a value. Read more

impl AsMut<[u8]> for BytesMut
[src]

Performs the conversion.

impl PartialOrd<BytesMut> for BytesMut
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This method returns an ordering between self and other values if one exists. Read more

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

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

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

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

impl PartialOrd<[u8]> for BytesMut
[src]

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

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

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

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

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

impl PartialOrd<BytesMut> for [u8]
[src]

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

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

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

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

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

impl PartialOrd<str> for BytesMut
[src]

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

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

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

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

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

impl PartialOrd<BytesMut> for str
[src]

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

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

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

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

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

impl PartialOrd<Vec<u8>> for BytesMut
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This method returns an ordering between self and other values if one exists. Read more

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

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

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

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

impl PartialOrd<BytesMut> for Vec<u8>
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This method returns an ordering between self and other values if one exists. Read more

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

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

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

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

impl PartialOrd<String> for BytesMut
[src]

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

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

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

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

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

impl PartialOrd<BytesMut> for String
[src]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

impl<'a> PartialOrd<BytesMut> for &'a str
[src]

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

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

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

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

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

impl Default for BytesMut
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Returns the "default value" for a type. Read more

impl Ord for BytesMut
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This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

impl PartialEq<BytesMut> for BytesMut
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This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

impl PartialEq<[u8]> for BytesMut
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This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

impl PartialEq<BytesMut> for [u8]
[src]

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

This method tests for !=.

impl PartialEq<str> for BytesMut
[src]

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

This method tests for !=.

impl PartialEq<BytesMut> for str
[src]

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

This method tests for !=.

impl PartialEq<Vec<u8>> for BytesMut
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This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

impl PartialEq<BytesMut> for Vec<u8>
[src]

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

This method tests for !=.

impl PartialEq<String> for BytesMut
[src]

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

This method tests for !=.

impl PartialEq<BytesMut> for String
[src]

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

This method tests for !=.

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

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

This method tests for !=.

impl<'a> PartialEq<BytesMut> for &'a [u8]
[src]

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

This method tests for !=.

impl<'a> PartialEq<BytesMut> for &'a str
[src]

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

This method tests for !=.

impl PartialEq<BytesMut> for Bytes
[src]

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

This method tests for !=.

impl PartialEq<Bytes> for BytesMut
[src]

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

This method tests for !=.

impl From<BytesMut> for Bytes
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Performs the conversion.

impl From<Vec<u8>> for BytesMut
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Performs the conversion.

impl From<String> for BytesMut
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Performs the conversion.

impl<'a> From<&'a [u8]> for BytesMut
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Performs the conversion.

impl<'a> From<&'a str> for BytesMut
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Performs the conversion.

impl From<Bytes> for BytesMut
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Performs the conversion.

impl AsRef<[u8]> for BytesMut
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Performs the conversion.

impl Clone for BytesMut
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Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl IntoIterator for BytesMut
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The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

impl<'a> IntoIterator for &'a BytesMut
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The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

impl Extend<u8> for BytesMut
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Extends a collection with the contents of an iterator. Read more

impl<'a> Extend<&'a u8> for BytesMut
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Extends a collection with the contents of an iterator. Read more

impl Eq for BytesMut
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impl Deref for BytesMut
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The resulting type after dereferencing.

Dereferences the value.

impl Hash for BytesMut
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Feeds this value into the given [Hasher]. Read more

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

impl DerefMut for BytesMut
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Mutably dereferences the value.

impl FromIterator<u8> for BytesMut
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Creates a value from an iterator. Read more

impl Debug for BytesMut
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Formats the value using the given formatter. Read more

impl Write for BytesMut
[src]

Writes a slice of bytes into this writer, returning whether the write succeeded. Read more

Glue for usage of the [write!] macro with implementors of this trait. Read more

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

impl Borrow<[u8]> for BytesMut
[src]

Immutably borrows from an owned value. Read more

impl BorrowMut<[u8]> for BytesMut
[src]

Mutably borrows from an owned value. Read more

Auto Trait Implementations

impl Send for BytesMut

impl Sync for BytesMut

Blanket Implementations

impl<T, U> Into for T where
    U: From<T>, 
[src]

Performs the conversion.

impl<T> ToOwned for T where
    T: Clone
[src]

Creates owned data from borrowed data, usually by cloning. Read more

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

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T> From for T
[src]

Performs the conversion.

impl<I> IntoIterator for I where
    I: Iterator
[src]

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

impl<T, U> TryFrom for T where
    T: From<U>, 
[src]

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

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> Borrow for T where
    T: ?Sized
[src]

Immutably borrows from an owned value. Read more

impl<T> BorrowMut for T where
    T: ?Sized
[src]

Mutably borrows from an owned value. Read more

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> Any for T where
    T: 'static + ?Sized
[src]

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

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more