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|
use std::cmp::Ordering;
use std::collections::VecDeque;
use bytes::BytesMut;
pub use bytes::Bytes;
/// A circular buffer of bytes, internally represented as a list of Bytes
/// for optimization, but that for all intent and purposes acts just like
/// a big byte slice which can be extended on the right and from which
/// stuff can be taken on the left.
pub struct BytesBuf {
buf: VecDeque<Bytes>,
buf_len: usize,
}
impl BytesBuf {
/// Creates a new empty BytesBuf
pub fn new() -> Self {
Self {
buf: VecDeque::new(),
buf_len: 0,
}
}
/// Returns the number of bytes stored in the BytesBuf
#[inline]
pub fn len(&self) -> usize {
self.buf_len
}
/// Returns true iff the BytesBuf contains zero bytes
#[inline]
pub fn is_empty(&self) -> bool {
self.buf_len == 0
}
/// Adds some bytes to the right of the buffer
pub fn extend(&mut self, b: Bytes) {
if !b.is_empty() {
self.buf_len += b.len();
self.buf.push_back(b);
}
}
/// Takes the whole content of the buffer and returns it as a single Bytes unit
pub fn take_all(&mut self) -> Bytes {
if self.buf.is_empty() {
Bytes::new()
} else if self.buf.len() == 1 {
self.buf_len = 0;
self.buf.pop_back().unwrap()
} else {
let mut ret = BytesMut::with_capacity(self.buf_len);
for b in self.buf.iter() {
ret.extend_from_slice(&b[..]);
}
self.buf.clear();
self.buf_len = 0;
ret.freeze()
}
}
/// Takes at most max_len bytes from the left of the buffer
pub fn take_max(&mut self, max_len: usize) -> Bytes {
if self.buf_len <= max_len {
self.take_all()
} else {
self.take_exact_ok(max_len)
}
}
/// Take exactly len bytes from the left of the buffer, returns None if
/// the BytesBuf doesn't contain enough data
pub fn take_exact(&mut self, len: usize) -> Option<Bytes> {
if self.buf_len < len {
None
} else {
Some(self.take_exact_ok(len))
}
}
fn take_exact_ok(&mut self, len: usize) -> Bytes {
assert!(len <= self.buf_len);
let front = self.buf.pop_front().unwrap();
match front.len().cmp(&len) {
Ordering::Greater => {
self.buf.push_front(front.slice(len..));
self.buf_len -= len;
front.slice(..len)
}
Ordering::Equal => {
self.buf_len -= len;
front
}
Ordering::Less => {
let mut ret = BytesMut::with_capacity(len);
ret.extend_from_slice(&front[..]);
self.buf_len -= front.len();
while ret.len() < len {
let front = self.buf.pop_front().unwrap();
if front.len() > len - ret.len() {
let take = len - ret.len();
ret.extend_from_slice(&front[..take]);
self.buf.push_front(front.slice(take..));
self.buf_len -= take;
break;
} else {
ret.extend_from_slice(&front[..]);
self.buf_len -= front.len();
}
}
ret.freeze()
}
}
}
/// Return the internal sequence of Bytes slices that make up the buffer
pub fn into_slices(self) -> VecDeque<Bytes> {
self.buf
}
}
impl Default for BytesBuf {
fn default() -> Self {
Self::new()
}
}
impl From<Bytes> for BytesBuf {
fn from(b: Bytes) -> BytesBuf {
let mut ret = BytesBuf::new();
ret.extend(b);
ret
}
}
impl From<BytesBuf> for Bytes {
fn from(mut b: BytesBuf) -> Bytes {
b.take_all()
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_bytes_buf() {
let mut buf = BytesBuf::new();
assert!(buf.len() == 0);
assert!(buf.is_empty());
buf.extend(Bytes::from(b"Hello, world!".to_vec()));
assert!(buf.len() == 13);
assert!(!buf.is_empty());
buf.extend(Bytes::from(b"1234567890".to_vec()));
assert!(buf.len() == 23);
assert!(!buf.is_empty());
assert_eq!(
buf.take_all(),
Bytes::from(b"Hello, world!1234567890".to_vec())
);
assert!(buf.len() == 0);
assert!(buf.is_empty());
buf.extend(Bytes::from(b"1234567890".to_vec()));
buf.extend(Bytes::from(b"Hello, world!".to_vec()));
assert!(buf.len() == 23);
assert!(!buf.is_empty());
assert_eq!(buf.take_max(12), Bytes::from(b"1234567890He".to_vec()));
assert!(buf.len() == 11);
assert_eq!(buf.take_exact(12), None);
assert!(buf.len() == 11);
assert_eq!(
buf.take_exact(11),
Some(Bytes::from(b"llo, world!".to_vec()))
);
assert!(buf.len() == 0);
assert!(buf.is_empty());
}
}
|
