Trait bytes::buf::Buf

source · [−]
pub trait Buf {

Show 36 methods    fn remaining(&self) -> usize;
    fn chunk(&self) -> &[u8]ⓘNotable traits for &[u8]impl<'_> Read for &[u8]impl<'_> Write for &mut [u8];
    fn advance(&mut self, cnt: usize);

    fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> 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(&mut self) -> u16 { ... }
    fn get_u16_le(&mut self) -> u16 { ... }
    fn get_i16(&mut self) -> i16 { ... }
    fn get_i16_le(&mut self) -> i16 { ... }
    fn get_u32(&mut self) -> u32 { ... }
    fn get_u32_le(&mut self) -> u32 { ... }
    fn get_i32(&mut self) -> i32 { ... }
    fn get_i32_le(&mut self) -> i32 { ... }
    fn get_u64(&mut self) -> u64 { ... }
    fn get_u64_le(&mut self) -> u64 { ... }
    fn get_i64(&mut self) -> i64 { ... }
    fn get_i64_le(&mut self) -> i64 { ... }
    fn get_u128(&mut self) -> u128 { ... }
    fn get_u128_le(&mut self) -> u128 { ... }
    fn get_i128(&mut self) -> i128 { ... }
    fn get_i128_le(&mut self) -> i128 { ... }
    fn get_uint(&mut self, nbytes: usize) -> u64 { ... }
    fn get_uint_le(&mut self, nbytes: usize) -> u64 { ... }
    fn get_int(&mut self, nbytes: usize) -> i64 { ... }
    fn get_int_le(&mut self, nbytes: usize) -> i64 { ... }
    fn get_f32(&mut self) -> f32 { ... }
    fn get_f32_le(&mut self) -> f32 { ... }
    fn get_f64(&mut self) -> f64 { ... }
    fn get_f64_le(&mut self) -> f64 { ... }
    fn copy_to_bytes(&mut self, len: usize) -> Bytes { ... }
    fn take(self, limit: usize) -> Take<Self>
    where
        Self: Sized,
    { ... }
    fn chain<U: Buf>(self, next: U) -> Chain<Self, U>
    where
        Self: Sized,
    { ... }
    fn reader(self) -> Reader<Self>ⓘNotable traits for Reader<B>impl<B: Buf + Sized> Read for Reader<B>
    where
        Self: Sized,
    { ... }

}
Expand description

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 &[u8].

use bytes::Buf;

let mut buf = &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

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 chunk().

Examples
use bytes::Buf;

let mut buf = &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.

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;

let mut buf = &b"hello world"[..];

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

buf.advance(6);

assert_eq!(buf.chunk(), &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 chunk() should return an empty slice.

Advance the internal cursor of the Buf

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

Examples
use bytes::Buf;

let mut buf = &b"hello world"[..];

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

buf.advance(6);

assert_eq!(buf.chunk(), &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.

Provided Methods

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

If the Buf is backed by disjoint slices of bytes, chunk_vectored enables fetching more than one slice at once. dst is a slice of IoSlice 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 chunk_vectored 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 chunk_vectored must return 0 without mutating dst.

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

Returns true if there are any more bytes to consume

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

Examples
use bytes::Buf;

let mut buf = &b"a"[..];

assert!(buf.has_remaining());

buf.get_u8();

assert!(!buf.has_remaining());

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;

let mut buf = &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()

Gets an unsigned 8 bit integer from self.

The current position is advanced by 1.

Examples
use bytes::Buf;

let mut buf = &b"\x08 hello"[..];
assert_eq!(8, buf.get_u8());
Panics

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

Gets a signed 8 bit integer from self.

The current position is advanced by 1.

Examples
use bytes::Buf;

let mut buf = &b"\x08 hello"[..];
assert_eq!(8, buf.get_i8());
Panics

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

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

The current position is advanced by 2.

Examples
use bytes::Buf;

let mut buf = &b"\x08\x09 hello"[..];
assert_eq!(0x0809, buf.get_u16());
Panics

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

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

The current position is advanced by 2.

Examples
use bytes::Buf;

let mut buf = &b"\x09\x08 hello"[..];
assert_eq!(0x0809, buf.get_u16_le());
Panics

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

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

The current position is advanced by 2.

Examples
use bytes::Buf;

let mut buf = &b"\x08\x09 hello"[..];
assert_eq!(0x0809, buf.get_i16());
Panics

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

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

The current position is advanced by 2.

Examples
use bytes::Buf;

let mut buf = &b"\x09\x08 hello"[..];
assert_eq!(0x0809, buf.get_i16_le());
Panics

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

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;

let mut buf = &b"\x08\x09\xA0\xA1 hello"[..];
assert_eq!(0x0809A0A1, buf.get_u32());
Panics

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

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;

let mut buf = &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.

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

The current position is advanced by 4.

Examples
use bytes::Buf;

let mut buf = &b"\x08\x09\xA0\xA1 hello"[..];
assert_eq!(0x0809A0A1, buf.get_i32());
Panics

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

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

The current position is advanced by 4.

Examples
use bytes::Buf;

let mut buf = &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.

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

The current position is advanced by 8.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"[..];
assert_eq!(0x0102030405060708, buf.get_u64());
Panics

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

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

The current position is advanced by 8.

Examples
use bytes::Buf;

let mut buf = &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.

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

The current position is advanced by 8.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"[..];
assert_eq!(0x0102030405060708, buf.get_i64());
Panics

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

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

The current position is advanced by 8.

Examples
use bytes::Buf;

let mut buf = &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.

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

The current position is advanced by 16.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16 hello"[..];
assert_eq!(0x01020304050607080910111213141516, buf.get_u128());
Panics

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

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

The current position is advanced by 16.

Examples
use bytes::Buf;

let mut buf = &b"\x16\x15\x14\x13\x12\x11\x10\x09\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
assert_eq!(0x01020304050607080910111213141516, buf.get_u128_le());
Panics

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

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

The current position is advanced by 16.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16 hello"[..];
assert_eq!(0x01020304050607080910111213141516, buf.get_i128());
Panics

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

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

The current position is advanced by 16.

Examples
use bytes::Buf;

let mut buf = &b"\x16\x15\x14\x13\x12\x11\x10\x09\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
assert_eq!(0x01020304050607080910111213141516, buf.get_i128_le());
Panics

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

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

The current position is advanced by nbytes.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03 hello"[..];
assert_eq!(0x010203, buf.get_uint(3));
Panics

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

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

The current position is advanced by nbytes.

Examples
use bytes::Buf;

let mut buf = &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.

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

The current position is advanced by nbytes.

Examples
use bytes::Buf;

let mut buf = &b"\x01\x02\x03 hello"[..];
assert_eq!(0x010203, buf.get_int(3));
Panics

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

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

The current position is advanced by nbytes.

Examples
use bytes::Buf;

let mut buf = &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.

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;

let mut buf = &b"\x3F\x99\x99\x9A hello"[..];
assert_eq!(1.2f32, buf.get_f32());
Panics

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

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;

let mut buf = &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.

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;

let mut buf = &b"\x3F\xF3\x33\x33\x33\x33\x33\x33 hello"[..];
assert_eq!(1.2f64, buf.get_f64());
Panics

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

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;

let mut buf = &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.

Consumes len bytes inside self and returns new instance of Bytes with this data.

This function may be optimized by the underlying type to avoid actual copies. For example, Bytes implementation will do a shallow copy (ref-count increment).

Examples
use bytes::Buf;

let bytes = (&b"hello world"[..]).copy_to_bytes(5);
assert_eq!(&bytes[..], &b"hello"[..]);

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};

let mut buf = b"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");

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::Buf;

let mut chain = b"hello "[..].chain(&b"world"[..]);

let full = chain.copy_to_bytes(11);
assert_eq!(full.chunk(), b"hello world");

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

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

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"[..]);

Implementations on Foreign Types

Implementors