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use std::io::Result as IoResult;
use std::io::Write;
pub struct Encoder<W> where W: Write {
output: W,
chunks_size: usize,
buffer: Vec<u8>,
}
impl<W> Encoder<W> where W: Write {
pub fn new(output: W) -> Encoder<W> {
Encoder::with_chunks_size(output, 8192)
}
pub fn with_chunks_size(output: W, chunks: usize) -> Encoder<W> {
Encoder {
output: output,
chunks_size: chunks,
buffer: Vec::with_capacity(0),
}
}
}
fn send<W>(output: &mut W, data: &[u8]) -> IoResult<()> where W: Write {
try!(write!(output, "{:x}\r\n", data.len()));
try!(output.write_all(data));
try!(write!(output, "\r\n"));
Ok(())
}
impl<W> Write for Encoder<W> where W: Write {
fn write(&mut self, buf: &[u8]) -> IoResult<usize> {
try!(self.buffer.write_all(buf));
while self.buffer.len() >= self.chunks_size {
let rest = {
let (to_send, rest) = self.buffer.split_at_mut(self.chunks_size);
try!(send(&mut self.output, to_send));
rest.to_vec()
};
self.buffer = rest;
}
Ok(buf.len())
}
fn flush(&mut self) -> IoResult<()> {
if self.buffer.len() == 0 {
return Ok(());
}
try!(send(&mut self.output, &self.buffer));
self.buffer.clear();
Ok(())
}
}
impl<W> Drop for Encoder<W> where W: Write {
fn drop(&mut self) {
self.flush().ok();
send(&mut self.output, &[]).ok();
}
}
#[cfg(test)]
mod test {
use std::io;
use std::io::Write;
use std::str::from_utf8;
use super::Encoder;
#[test]
fn test() {
let mut source = io::Cursor::new("hello world".to_string().into_bytes());
let mut dest: Vec<u8> = vec![];
{
let mut encoder = Encoder::with_chunks_size(dest.by_ref(), 5);
io::copy(&mut source, &mut encoder).unwrap();
}
let output = from_utf8(&dest).unwrap();
assert_eq!(output, "5\r\nhello\r\n5\r\n worl\r\n1\r\nd\r\n0\r\n\r\n");
}
}