Trait bytes::Buf

pub trait Buf {
    fn remaining(&self) -> usize;
    fn bytes(&self) -> &[u8];
    fn advance(&mut self, cnt: usize);

    fn bytes_vec<'a>(&'a self, dst: &mut [&'a IoVec]) -> usize { ... }
    fn has_remaining(&self) -> bool { ... }
    fn copy_to_slice(&mut self, dst: &mut [u8]) { ... }
    fn get_u8(&mut self) -> u8 { ... }
    fn get_i8(&mut self) -> i8 { ... }
    fn get_u16_be(&mut self) -> u16 { ... }
    fn get_u16_le(&mut self) -> u16 { ... }
    fn get_i16_be(&mut self) -> i16 { ... }
    fn get_i16_le(&mut self) -> i16 { ... }
    fn get_u32_be(&mut self) -> u32 { ... }
    fn get_u32_le(&mut self) -> u32 { ... }
    fn get_i32_be(&mut self) -> i32 { ... }
    fn get_i32_le(&mut self) -> i32 { ... }
    fn get_u64_be(&mut self) -> u64 { ... }
    fn get_u64_le(&mut self) -> u64 { ... }
    fn get_i64_be(&mut self) -> i64 { ... }
    fn get_i64_le(&mut self) -> i64 { ... }
    fn get_uint_be(&mut self, nbytes: usize) -> u64 { ... }
    fn get_uint_le(&mut self, nbytes: usize) -> u64 { ... }
    fn get_int_be(&mut self, nbytes: usize) -> i64 { ... }
    fn get_int_le(&mut self, nbytes: usize) -> i64 { ... }
    fn get_f32_be(&mut self) -> f32 { ... }
    fn get_f32_le(&mut self) -> f32 { ... }
    fn get_f64_be(&mut self) -> f64 { ... }
    fn get_f64_le(&mut self) -> f64 { ... }
    fn collect<B>(self) -> B
    where
        Self: Sized,
        B: FromBuf,
    { ... }
    fn take(self, limit: usize) -> Take<Self>
    where
        Self: Sized,
    { ... }
    fn chain<U>(self, next: U) -> Chain<Self, U::Buf>
    where
        U: IntoBuf,
        Self: Sized,
    { ... }
    fn by_ref(&mut self) -> &mut Self
    where
        Self: Sized,
    { ... }
    fn reader(self) -> Reader<Self>
    where
        Self: Sized,
    { ... }
    fn iter(self) -> Iter<Self>
    where
        Self: Sized,
    { ... }
}

Read bytes from a buffer.

A buffer stores bytes in memory such that read operations are infallible. The underlying storage may or may not be in contiguous memory. A Buf value is a cursor into the buffer. Reading from Buf advances the cursor position. It can be thought of as an efficient Iterator for collections of bytes.

The simplest Buf is a Cursor wrapping a [u8].

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"hello world");

assert_eq!(b'h', buf.get_u8());
assert_eq!(b'e', buf.get_u8());
assert_eq!(b'l', buf.get_u8());

let mut rest = [0; 8];
buf.copy_to_slice(&mut rest);

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

Required methods

fn remaining(&self) -> usize

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

This value is greater than or equal to the length of the slice returned by bytes.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"hello world");

assert_eq!(buf.remaining(), 11);

buf.get_u8();

assert_eq!(buf.remaining(), 10);

Implementer notes

Implementations of remaining should ensure that the return value does not change unless a call is made to advance or any other function that is documented to change the Buf's current position.

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

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

This is a lower level function. Most operations are done with other functions.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"hello world");

assert_eq!(buf.bytes(), b"hello world");

buf.advance(6);

assert_eq!(buf.bytes(), b"world");

Implementer notes

This function should never panic. Once the end of the buffer is reached, i.e., Buf::remaining returns 0, calls to bytes should return an empty slice.

fn advance(&mut self, cnt: usize)

Advance the internal cursor of the Buf

The next call to bytes will return a slice starting cnt bytes further into the underlying buffer.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"hello world");

assert_eq!(buf.bytes(), b"hello world");

buf.advance(6);

assert_eq!(buf.bytes(), b"world");

Panics

This function may panic if cnt > self.remaining().

Implementer notes

It is recommended for implementations of advance to panic if cnt > self.remaining(). If the implementation does not panic, the call must behave as if cnt == self.remaining().

A call with cnt == 0 should never panic and be a no-op.

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Provided methods

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

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

If the Buf is backed by disjoint slices of bytes, bytes_vec enables fetching more than one slice at once. dst is a slice of IoVec references, enabling the slice to be directly used with writev without any further conversion. The sum of the lengths of all the buffers in dst will be less than or equal to Buf::remaining().

The entries in dst will be overwritten, but the data contained by the slices will not be modified. If bytes_vec does not fill every entry in dst, then dst is guaranteed to contain all remaining slices in `self.

This is a lower level function. Most operations are done with other functions.

Implementer notes

This function should never panic. Once the end of the buffer is reached, i.e., Buf::remaining returns 0, calls to bytes_vec must return 0 without mutating dst.

Implementations should also take care to properly handle being called with dst being a zero length slice.

fn has_remaining(&self) -> bool

Returns true if there are any more bytes to consume

This is equivalent to self.remaining() != 0.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"a");

assert!(buf.has_remaining());

buf.get_u8();

assert!(!buf.has_remaining());

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

Copies bytes from self into dst.

The cursor is advanced by the number of bytes copied. self must have enough remaining bytes to fill dst.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"hello world");
let mut dst = [0; 5];

buf.copy_to_slice(&mut dst);
assert_eq!(b"hello", &dst);
assert_eq!(6, buf.remaining());

Panics

This function panics if self.remaining() < dst.len()

fn get_u8(&mut self) -> u8

Gets an unsigned 8 bit integer from self.

The current position is advanced by 1.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08 hello");
assert_eq!(8, buf.get_u8());

Panics

This function panics if there is no more remaining data in self.

fn get_i8(&mut self) -> i8

Gets a signed 8 bit integer from self.

The current position is advanced by 1.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08 hello");
assert_eq!(8, buf.get_i8());

Panics

This function panics if there is no more remaining data in self.

fn get_u16_be(&mut self) -> u16

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

The current position is advanced by 2.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x09 hello");
assert_eq!(0x0809, buf.get_u16_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_u16_le(&mut self) -> u16

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

The current position is advanced by 2.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x09\x08 hello");
assert_eq!(0x0809, buf.get_u16_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_i16_be(&mut self) -> i16

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

The current position is advanced by 2.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x09 hello");
assert_eq!(0x0809, buf.get_i16_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_i16_le(&mut self) -> i16

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

The current position is advanced by 2.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x09\x08 hello");
assert_eq!(0x0809, buf.get_i16_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_u32_be(&mut self) -> u32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x09\xA0\xA1 hello");
assert_eq!(0x0809A0A1, buf.get_u32_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_u32_le(&mut self) -> u32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\xA1\xA0\x09\x08 hello");
assert_eq!(0x0809A0A1, buf.get_u32_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_i32_be(&mut self) -> i32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x09\xA0\xA1 hello");
assert_eq!(0x0809A0A1, buf.get_i32_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_i32_le(&mut self) -> i32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\xA1\xA0\x09\x08 hello");
assert_eq!(0x0809A0A1, buf.get_i32_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_u64_be(&mut self) -> u64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x01\x02\x03\x04\x05\x06\x07\x08 hello");
assert_eq!(0x0102030405060708, buf.get_u64_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_u64_le(&mut self) -> u64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x07\x06\x05\x04\x03\x02\x01 hello");
assert_eq!(0x0102030405060708, buf.get_u64_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_i64_be(&mut self) -> i64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x01\x02\x03\x04\x05\x06\x07\x08 hello");
assert_eq!(0x0102030405060708, buf.get_i64_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_i64_le(&mut self) -> i64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x08\x07\x06\x05\x04\x03\x02\x01 hello");
assert_eq!(0x0102030405060708, buf.get_i64_le());

Panics

This function panics if there is not enough remaining data in self.

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

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

The current position is advanced by nbytes.

Examples

use bytes::{Buf, BigEndian};
use std::io::Cursor;

let mut buf = Cursor::new(b"\x01\x02\x03 hello");
assert_eq!(0x010203, buf.get_uint_be(3));

Panics

This function panics if there is not enough remaining data in self.

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

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

The current position is advanced by nbytes.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x03\x02\x01 hello");
assert_eq!(0x010203, buf.get_uint_le(3));

Panics

This function panics if there is not enough remaining data in self.

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

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

The current position is advanced by nbytes.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x01\x02\x03 hello");
assert_eq!(0x010203, buf.get_int_be(3));

Panics

This function panics if there is not enough remaining data in self.

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

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

The current position is advanced by nbytes.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x03\x02\x01 hello");
assert_eq!(0x010203, buf.get_int_le(3));

Panics

This function panics if there is not enough remaining data in self.

fn get_f32_be(&mut self) -> f32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x3F\x99\x99\x9A hello");
assert_eq!(1.2f32, buf.get_f32_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_f32_le(&mut self) -> f32

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

The current position is advanced by 4.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x9A\x99\x99\x3F hello");
assert_eq!(1.2f32, buf.get_f32_le());

Panics

This function panics if there is not enough remaining data in self.

fn get_f64_be(&mut self) -> f64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x3F\xF3\x33\x33\x33\x33\x33\x33 hello");
assert_eq!(1.2f64, buf.get_f64_be());

Panics

This function panics if there is not enough remaining data in self.

fn get_f64_le(&mut self) -> f64

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

The current position is advanced by 8.

Examples

use bytes::Buf;
use std::io::Cursor;

let mut buf = Cursor::new(b"\x33\x33\x33\x33\x33\x33\xF3\x3F hello");
assert_eq!(1.2f64, buf.get_f64_le());

Panics

This function panics if there is not enough remaining data in self.

fn collect<B>(self) -> B where
    Self: Sized,
    B: FromBuf, 

Transforms a Buf into a concrete buffer.

collect() can operate on any value that implements Buf, and turn it into the relevent concrete buffer type.

Examples

Collecting a buffer and loading the contents into a Vec<u8>.

use bytes::{Buf, Bytes, IntoBuf};

let buf = Bytes::from(&b"hello world"[..]).into_buf();
let vec: Vec<u8> = buf.collect();

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

fn take(self, limit: usize) -> Take<Self> where
    Self: Sized, 

Creates an adaptor which will read at most limit bytes from self.

This function returns a new instance of Buf which will read at most limit bytes.

Examples

use bytes::{Buf, BufMut};
use std::io::Cursor;

let mut buf = Cursor::new("hello world").take(5);
let mut dst = vec![];

dst.put(&mut buf);
assert_eq!(dst, b"hello");

let mut buf = buf.into_inner();
dst.clear();
dst.put(&mut buf);
assert_eq!(dst, b" world");

fn chain<U>(self, next: U) -> Chain<Self, U::Buf> where
    U: IntoBuf,
    Self: Sized, 

Creates an adaptor which will chain this buffer with another.

The returned Buf instance will first consume all bytes from self. Afterwards the output is equivalent to the output of next.

Examples

use bytes::{Bytes, Buf, IntoBuf};
use bytes::buf::Chain;

let buf = Bytes::from(&b"hello "[..]).into_buf()
            .chain(Bytes::from(&b"world"[..]));

let full: Bytes = buf.collect();
assert_eq!(full[..], b"hello world"[..]);

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

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

The returned adaptor also implements Buf and will simply borrow self.

Examples

use bytes::{Buf, BufMut};
use std::io::Cursor;

let mut buf = Cursor::new("hello world");
let mut dst = vec![];

{
    let mut reference = buf.by_ref();
    dst.put(&mut reference.take(5));
    assert_eq!(dst, b"hello");
} // drop our &mut reference so we can use `buf` again

dst.clear();
dst.put(&mut buf);
assert_eq!(dst, b" world");

Important traits for Reader<B>

impl<B: Buf + Sized> Read for Reader<B>

fn reader(self) -> Reader<Self> where
    Self: Sized, 

Creates an adaptor which implements the Read trait for self.

This function returns a new value which implements Read by adapting the Read trait functions to the Buf trait functions. Given that Buf operations are infallible, none of the Read functions will return with Err.

Examples

use bytes::{Buf, IntoBuf, Bytes};
use std::io::Read;

let buf = Bytes::from("hello world").into_buf();

let mut reader = buf.reader();
let mut dst = [0; 1024];

let num = reader.read(&mut dst).unwrap();

assert_eq!(11, num);
assert_eq!(&dst[..11], b"hello world");

Important traits for Iter<T>

impl<T: Buf> Iterator for Iter<T> type Item = u8;

fn iter(self) -> Iter<Self> where
    Self: Sized, 

Returns an iterator over the bytes contained by the buffer.

Examples

use bytes::{Buf, IntoBuf, Bytes};

let buf = Bytes::from(&b"abc"[..]).into_buf();
let mut iter = buf.iter();

assert_eq!(iter.next(), Some(b'a'));
assert_eq!(iter.next(), Some(b'b'));
assert_eq!(iter.next(), Some(b'c'));
assert_eq!(iter.next(), None);

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Implementations on Foreign Types

impl<'a, T: Buf + ?Sized> Buf for &'a mut T

fn remaining(&self) -> usize

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

fn bytes_vec<'b>(&'b self, dst: &mut [&'b IoVec]) -> usize

fn advance(&mut self, cnt: usize)

impl<T: Buf + ?Sized> Buf for Box<T>

fn remaining(&self) -> usize

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

fn bytes_vec<'b>(&'b self, dst: &mut [&'b IoVec]) -> usize

fn advance(&mut self, cnt: usize)

impl<T: AsRef<[u8]>> Buf for Cursor<T>

fn remaining(&self) -> usize

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

fn advance(&mut self, cnt: usize)

impl Buf for Option<[u8; 1]>

fn remaining(&self) -> usize

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

fn advance(&mut self, cnt: usize)

impl Buf for VecDeque<u8>

fn remaining(&self) -> usize

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

fn advance(&mut self, cnt: usize)

impl<L, R> Buf for Either<L, R> where
    L: Buf,
    R: Buf, 

fn remaining(&self) -> usize

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

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

fn advance(&mut self, cnt: usize)

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

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Implementors

impl<T, U> Buf for Chain<T, U> where
    T: Buf,
    U: Buf, 

fn remaining(&self) -> usize

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

fn advance(&mut self, cnt: usize)

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

impl<T: Buf> Buf for Take<T>

fn remaining(&self) -> usize

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

fn advance(&mut self, cnt: usize)

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