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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// <https://github.com/rust-lang/rust/blob/HEAD/COPYRIGHT>.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cmp;
use std::io;
use std::io::prelude::*;
use std::mem;
pub struct BufReader<R> {
inner: R,
buf: Box<[u8]>,
pos: usize,
cap: usize,
}
impl<R> ::std::fmt::Debug for BufReader<R>
where
R: ::std::fmt::Debug,
{
fn fmt(&self, fmt: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
fmt.debug_struct("BufReader")
.field("reader", &self.inner)
.field(
"buffer",
&format_args!("{}/{}", self.cap - self.pos, self.buf.len()),
)
.finish()
}
}
impl<R: Read> BufReader<R> {
pub fn new(inner: R) -> BufReader<R> {
BufReader::with_buf(vec![0; 32 * 1024], inner)
}
pub fn with_buf(buf: Vec<u8>, inner: R) -> BufReader<R> {
BufReader {
inner,
buf: buf.into_boxed_slice(),
pos: 0,
cap: 0,
}
}
}
impl<R> BufReader<R> {
pub fn get_ref(&self) -> &R {
&self.inner
}
pub fn get_mut(&mut self) -> &mut R {
&mut self.inner
}
pub fn into_inner(self) -> R {
self.inner
}
pub fn reset(&mut self, inner: R) -> R {
self.pos = 0;
self.cap = 0;
mem::replace(&mut self.inner, inner)
}
}
impl<R: Read> Read for BufReader<R> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
// If we don't have any buffered data and we're doing a massive read
// (larger than our internal buffer), bypass our internal buffer
// entirely.
if self.pos == self.cap && buf.len() >= self.buf.len() {
return self.inner.read(buf);
}
let nread = {
let mut rem = self.fill_buf()?;
rem.read(buf)?
};
self.consume(nread);
Ok(nread)
}
}
impl<R: Read> BufRead for BufReader<R> {
fn fill_buf(&mut self) -> io::Result<&[u8]> {
// If we've reached the end of our internal buffer then we need to fetch
// some more data from the underlying reader.
if self.pos == self.cap {
self.cap = self.inner.read(&mut self.buf)?;
self.pos = 0;
}
Ok(&self.buf[self.pos..self.cap])
}
fn consume(&mut self, amt: usize) {
self.pos = cmp::min(self.pos + amt, self.cap);
}
}
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