diff options
Diffstat (limited to 'third_party/rust/bytes/src/buf/chain.rs')
| -rw-r--r-- | third_party/rust/bytes/src/buf/chain.rs | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/third_party/rust/bytes/src/buf/chain.rs b/third_party/rust/bytes/src/buf/chain.rs new file mode 100644 index 0000000000..78979a1231 --- /dev/null +++ b/third_party/rust/bytes/src/buf/chain.rs @@ -0,0 +1,242 @@ +use crate::buf::{IntoIter, UninitSlice}; +use crate::{Buf, BufMut, Bytes}; + +#[cfg(feature = "std")] +use std::io::IoSlice; + +/// A `Chain` sequences two buffers. +/// +/// `Chain` is an adapter that links two underlying buffers and provides a +/// continuous view across both buffers. It is able to sequence either immutable +/// buffers ([`Buf`] values) or mutable buffers ([`BufMut`] values). +/// +/// This struct is generally created by calling [`Buf::chain`]. Please see that +/// function's documentation for more detail. +/// +/// # Examples +/// +/// ``` +/// use bytes::{Bytes, Buf}; +/// +/// let mut buf = (&b"hello "[..]) +/// .chain(&b"world"[..]); +/// +/// let full: Bytes = buf.copy_to_bytes(11); +/// assert_eq!(full[..], b"hello world"[..]); +/// ``` +/// +/// [`Buf::chain`]: trait.Buf.html#method.chain +/// [`Buf`]: trait.Buf.html +/// [`BufMut`]: trait.BufMut.html +#[derive(Debug)] +pub struct Chain<T, U> { + a: T, + b: U, +} + +impl<T, U> Chain<T, U> { + /// Creates a new `Chain` sequencing the provided values. + pub(crate) fn new(a: T, b: U) -> Chain<T, U> { + Chain { a, b } + } + + /// Gets a reference to the first underlying `Buf`. + /// + /// # Examples + /// + /// ``` + /// use bytes::Buf; + /// + /// let buf = (&b"hello"[..]) + /// .chain(&b"world"[..]); + /// + /// assert_eq!(buf.first_ref()[..], b"hello"[..]); + /// ``` + pub fn first_ref(&self) -> &T { + &self.a + } + + /// Gets a mutable reference to the first underlying `Buf`. + /// + /// # Examples + /// + /// ``` + /// use bytes::Buf; + /// + /// let mut buf = (&b"hello"[..]) + /// .chain(&b"world"[..]); + /// + /// buf.first_mut().advance(1); + /// + /// let full = buf.copy_to_bytes(9); + /// assert_eq!(full, b"elloworld"[..]); + /// ``` + pub fn first_mut(&mut self) -> &mut T { + &mut self.a + } + + /// Gets a reference to the last underlying `Buf`. + /// + /// # Examples + /// + /// ``` + /// use bytes::Buf; + /// + /// let buf = (&b"hello"[..]) + /// .chain(&b"world"[..]); + /// + /// assert_eq!(buf.last_ref()[..], b"world"[..]); + /// ``` + pub fn last_ref(&self) -> &U { + &self.b + } + + /// Gets a mutable reference to the last underlying `Buf`. + /// + /// # Examples + /// + /// ``` + /// use bytes::Buf; + /// + /// let mut buf = (&b"hello "[..]) + /// .chain(&b"world"[..]); + /// + /// buf.last_mut().advance(1); + /// + /// let full = buf.copy_to_bytes(10); + /// assert_eq!(full, b"hello orld"[..]); + /// ``` + pub fn last_mut(&mut self) -> &mut U { + &mut self.b + } + + /// Consumes this `Chain`, returning the underlying values. + /// + /// # Examples + /// + /// ``` + /// use bytes::Buf; + /// + /// let chain = (&b"hello"[..]) + /// .chain(&b"world"[..]); + /// + /// let (first, last) = chain.into_inner(); + /// assert_eq!(first[..], b"hello"[..]); + /// assert_eq!(last[..], b"world"[..]); + /// ``` + pub fn into_inner(self) -> (T, U) { + (self.a, self.b) + } +} + +impl<T, U> Buf for Chain<T, U> +where + T: Buf, + U: Buf, +{ + fn remaining(&self) -> usize { + self.a.remaining().checked_add(self.b.remaining()).unwrap() + } + + fn chunk(&self) -> &[u8] { + if self.a.has_remaining() { + self.a.chunk() + } else { + self.b.chunk() + } + } + + fn advance(&mut self, mut cnt: usize) { + let a_rem = self.a.remaining(); + + if a_rem != 0 { + if a_rem >= cnt { + self.a.advance(cnt); + return; + } + + // Consume what is left of a + self.a.advance(a_rem); + + cnt -= a_rem; + } + + self.b.advance(cnt); + } + + #[cfg(feature = "std")] + fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize { + let mut n = self.a.chunks_vectored(dst); + n += self.b.chunks_vectored(&mut dst[n..]); + n + } + + fn copy_to_bytes(&mut self, len: usize) -> Bytes { + let a_rem = self.a.remaining(); + if a_rem >= len { + self.a.copy_to_bytes(len) + } else if a_rem == 0 { + self.b.copy_to_bytes(len) + } else { + assert!( + len - a_rem <= self.b.remaining(), + "`len` greater than remaining" + ); + let mut ret = crate::BytesMut::with_capacity(len); + ret.put(&mut self.a); + ret.put((&mut self.b).take(len - a_rem)); + ret.freeze() + } + } +} + +unsafe impl<T, U> BufMut for Chain<T, U> +where + T: BufMut, + U: BufMut, +{ + fn remaining_mut(&self) -> usize { + self.a + .remaining_mut() + .saturating_add(self.b.remaining_mut()) + } + + fn chunk_mut(&mut self) -> &mut UninitSlice { + if self.a.has_remaining_mut() { + self.a.chunk_mut() + } else { + self.b.chunk_mut() + } + } + + unsafe fn advance_mut(&mut self, mut cnt: usize) { + let a_rem = self.a.remaining_mut(); + + if a_rem != 0 { + if a_rem >= cnt { + self.a.advance_mut(cnt); + return; + } + + // Consume what is left of a + self.a.advance_mut(a_rem); + + cnt -= a_rem; + } + + self.b.advance_mut(cnt); + } +} + +impl<T, U> IntoIterator for Chain<T, U> +where + T: Buf, + U: Buf, +{ + type Item = u8; + type IntoIter = IntoIter<Chain<T, U>>; + + fn into_iter(self) -> Self::IntoIter { + IntoIter::new(self) + } +} |