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-rw-r--r--src/bytes_buf.rs175
1 files changed, 175 insertions, 0 deletions
diff --git a/src/bytes_buf.rs b/src/bytes_buf.rs
new file mode 100644
index 0000000..931be82
--- /dev/null
+++ b/src/bytes_buf.rs
@@ -0,0 +1,175 @@
+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.len() == 0 {
+ 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();
+ if front.len() > len {
+ self.buf.push_front(front.slice(len..));
+ self.buf_len -= len;
+ front.slice(..len)
+ } else if front.len() == len {
+ self.buf_len -= len;
+ front
+ } else {
+ 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 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());
+ }
+}