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use std::default::Default;
use std::result::Result::Ok;
use std::sync::{Arc, Mutex};
use std::io;
use std::cmp;
#[derive(Clone)]
pub struct IoBuffer {
inner: Arc<Mutex<IoBufferInner>>,
}
struct IoBufferInner {
buf: Vec<u8>,
pos: usize,
}
impl IoBuffer {
pub fn new() -> Self {
IoBuffer {
inner: Arc::new(Mutex::new(IoBufferInner {
buf: vec![],
pos: 0,
})),
}
}
}
impl Default for IoBuffer {
fn default() -> Self {
Self::new()
}
}
impl io::Write for IoBuffer {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let mut lock = self.inner.lock().expect("lock poisoned");
lock.buf.extend_from_slice(buf);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl io::Read for IoBuffer {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let mut lock = self.inner.lock().expect("lock poisoned");
let len = cmp::min(lock.buf.len() - lock.pos, buf.len());
let pos = lock.pos;
buf[0..len].copy_from_slice(&lock.buf[pos..pos + len]);
lock.pos += len;
Ok(len)
}
}
mod tests {
#![allow(unused_imports)]
use super::IoBuffer;
use std::io::{Read, Write};
#[test]
fn test_simple_buffer_usage() {
let s1 = "This is some unexciting test data";
let s2 = "This is some more unexciting test data";
let mut buf = IoBuffer::new();
let mut dest = Vec::new();
let rc = buf.read_to_end(&mut dest).unwrap();
assert!(rc == 0, "{}", rc);
write!(buf, "{}", s1).unwrap();
write!(buf, "{}", s2).unwrap();
buf.flush().unwrap();
let rc = buf.read_to_end(&mut dest).unwrap();
assert!(
rc == s1.len() + s2.len(),
"{} != {}",
rc,
s1.len() + s2.len()
);
let s_out = String::from_utf8(dest).unwrap();
assert!(s_out == (s1.to_string() + s2), "{}", s_out);
}
}