Struct bitflags::__core::io::BufReader

pub struct BufReader<R> {
    // some fields omitted
}

The BufReader struct adds buffering to any reader.

It can be excessively inefficient to work directly with a Read instance. For example, every call to read on TcpStream results in a system call. A BufReader performs large, infrequent reads on the underlying Read and maintains an in-memory buffer of the results.

Examples

use std::io::prelude::*;
use std::io::BufReader;
use std::fs::File;

let mut f = try!(File::open("log.txt"));
let mut reader = BufReader::new(f);

let mut line = String::new();
let len = try!(reader.read_line(&mut line));
println!("First line is {} bytes long", len);

Methods

impl<R> BufReader<R> where R: Read

fn new(inner: R) -> BufReader<R>

Creates a new BufReader with a default buffer capacity.

Examples

use std::io::BufReader;
use std::fs::File;

let mut f = try!(File::open("log.txt"));
let mut reader = BufReader::new(f);

fn with_capacity(cap: usize, inner: R) -> BufReader<R>

Creates a new BufReader with the specified buffer capacity.

Examples

Creating a buffer with ten bytes of capacity:

use std::io::BufReader;
use std::fs::File;

let mut f = try!(File::open("log.txt"));
let mut reader = BufReader::with_capacity(10, f);

fn get_ref(&self) -> &R

Gets a reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

Examples

use std::io::BufReader;
use std::fs::File;

let mut f1 = try!(File::open("log.txt"));
let mut reader = BufReader::new(f1);

let f2 = reader.get_ref();

fn get_mut(&mut self) -> &mut R

Gets a mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

Examples

use std::io::BufReader;
use std::fs::File;

let mut f1 = try!(File::open("log.txt"));
let mut reader = BufReader::new(f1);

let f2 = reader.get_mut();

fn into_inner(self) -> R

Unwraps this BufReader, returning the underlying reader.

Note that any leftover data in the internal buffer is lost.

Examples

use std::io::BufReader;
use std::fs::File;

let mut f1 = try!(File::open("log.txt"));
let mut reader = BufReader::new(f1);

let f2 = reader.into_inner();

Trait Implementations

impl<R> Read for BufReader<R> where R: Read

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

fn by_ref(&mut self) -> &mut Self

fn bytes(self) -> Bytes<Self>

fn chars(self) -> Chars<Self>

fn chain<R>(self, next: R) -> Chain<Self, R> where R: Read

fn take(self, limit: u64) -> Take<Self>

impl<R> BufRead for BufReader<R> where R: Read

fn fill_buf(&mut self) -> Result<&[u8], Error>

fn consume(&mut self, amt: usize)

fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize, Error>

fn read_line(&mut self, buf: &mut String) -> Result<usize, Error>

fn split(self, byte: u8) -> Split<Self>

fn lines(self) -> Lines<Self>

impl<R> Debug for BufReader<R> where R: Debug

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

impl<R> Seek for BufReader<R> where R: Seek

fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>

Seek to an offset, in bytes, in the underlying reader.

The position used for seeking with SeekFrom::Current(_) is the position the underlying reader would be at if the BufReader had no internal buffer.

Seeking always discards the internal buffer, even if the seek position would otherwise fall within it. This guarantees that calling .unwrap() immediately after a seek yields the underlying reader at the same position.

See std::io::Seek for more details.

Note: In the edge case where you're seeking with SeekFrom::Current(n) where n minus the internal buffer length underflows an i64, two seeks will be performed instead of one. If the second seek returns Err, the underlying reader will be left at the same position it would have if you seeked to SeekFrom::Current(0).