Add buffers
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da80468266
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fdca7ada0b
209
src/buffers.rs
Normal file
209
src/buffers.rs
Normal file
@ -0,0 +1,209 @@
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struct ReadState {
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// rx: OwnedReadHalf,
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buffer: Vec<u8>,
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cursor: usize,
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}
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impl ReadState {
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fn has_next(&self) -> bool {
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self.buffer[..self.cursor]
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.iter()
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.position(|v| *v == b'\n')
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.is_some()
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}
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fn shift_ramaining(&mut self) {
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if !self.has_next() {
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return;
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}
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let pos = self.cursor;
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let mut last_old = 0;
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let mut last_new = 0;
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for (new, old) in (pos..self.buffer.len()).enumerate() {
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let v = self.buffer[old];
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if v == 0 {
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last_old = old;
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last_new = new;
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break;
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}
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// eprintln!("new {new} old {old} = {c} ({v})", c = v as char);
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self.buffer[new] = v;
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self.buffer[old] = 0;
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}
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for old in (last_new..pos).chain(last_old..self.buffer.len()) {
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// eprintln!("erase {old}");
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self.buffer[old] = 0;
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}
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self.cursor = 0;
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}
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fn next(&mut self) -> Option<&[u8]> {
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let Some(end) = self.buffer[self.cursor..self.buffer.len()]
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.iter()
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.position(|v| *v == b'\n').map(|n| n + self.cursor) else {
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return None;
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};
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// eprintln!("cursor {} end {end}", self.cursor);
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let s = &self.buffer[self.cursor..=end];
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self.cursor = (end + 1).min(self.buffer.len() - 1);
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Some(s)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn shift_empty() {
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let mut state = ReadState {
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buffer: vec![0, 0, 0, 0, 0, 0, 0, 0],
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cursor: 0,
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};
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state.shift_ramaining();
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let expected = vec![0, 0, 0, 0, 0, 0, 0, 0];
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn shift_single_unterminated() {
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let mut state = ReadState {
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buffer: vec![b'h', b'e', b'l', b'l', b'o', 0, 0, 0],
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cursor: 0,
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};
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state.shift_ramaining();
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let expected = vec![b'h', b'e', b'l', b'l', b'o', 0, 0, 0];
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn shift_single_terminated() {
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let mut state = ReadState {
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buffer: vec![b'h', b'e', b'l', b'l', b'o', b'\r', b'\n', 0],
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cursor: 0,
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};
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state.shift_ramaining();
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let expected = vec![b'h', b'e', b'l', b'l', b'o', b'\r', b'\n', 0];
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn shift_single_unterminated_moved() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\0\0\0\0".to_vec(),
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cursor: 7,
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};
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state.shift_ramaining();
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let expected = b"world\0\0\0\0\0\0\0\0\0\0\0".to_vec();
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn shift_single_terminated_moved() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\r\n\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 7,
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};
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state.shift_ramaining();
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let expected = b"world\r\n\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0".to_vec();
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn empty_next() {
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let mut state = ReadState {
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buffer: b"\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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assert_eq!(state.next(), None);
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}
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#[test]
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fn depleted_next() {
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let mut state = ReadState {
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buffer: b"hello\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 5,
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};
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assert_eq!(state.next(), None);
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}
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#[test]
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fn one_world_next() {
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let mut state = ReadState {
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buffer: b"hello\r\n\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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assert_eq!(state.next(), Some(b"hello\r\n".as_slice()));
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assert_eq!(state.cursor, 7);
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}
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#[test]
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fn tree_world_next() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\r\nnats\r\n\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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assert_eq!(state.next(), Some(b"hello\r\n".as_slice()));
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assert_eq!(state.cursor, 7);
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assert_eq!(state.next(), Some(b"world\r\n".as_slice()));
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assert_eq!(state.cursor, 14);
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assert_eq!(state.next(), Some(b"nats\r\n".as_slice()));
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assert_eq!(state.cursor, 20);
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assert_eq!(state.next(), None);
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assert_eq!(state.cursor, 20);
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}
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#[test]
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fn partial_move_and_shift() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\r\nnats\r\n\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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state.next();
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state.next();
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state.shift_ramaining();
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let expected = b"nats\r\n\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0".to_vec();
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn move_and_shift_non_terminated() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\r\nnats\0\0\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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state.next();
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state.next();
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state.next();
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state.shift_ramaining();
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let expected = b"nats\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0".to_vec();
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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#[test]
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fn full_move_and_shift() {
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let mut state = ReadState {
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buffer: b"hello\r\nworld\r\nnats\r\n\0\0\0\0\0\0\0\0".to_vec(),
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cursor: 0,
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};
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state.next();
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state.next();
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state.next();
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assert_eq!(state.cursor, 20);
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state.shift_ramaining();
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let expected = b"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0".to_vec();
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assert_eq!(
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std::str::from_utf8(&state.buffer),
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std::str::from_utf8(&expected),
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);
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}
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}
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