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Diffstat (limited to 'src/buf/ext/chain.rs')
| -rw-r--r-- | src/buf/ext/chain.rs | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/src/buf/ext/chain.rs b/src/buf/ext/chain.rs new file mode 100644 index 0000000..a1ec597 --- /dev/null +++ b/src/buf/ext/chain.rs @@ -0,0 +1,234 @@ +use crate::{Buf, BufMut}; +use crate::buf::IntoIter; + +use core::mem::MaybeUninit; + +#[cfg(feature = "std")] +use std::io::{IoSlice}; +#[cfg(feature = "std")] +use crate::buf::IoSliceMut; + +/// 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, buf::BufExt}; +/// +/// let mut buf = (&b"hello "[..]) +/// .chain(&b"world"[..]); +/// +/// let full: Bytes = buf.to_bytes(); +/// 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 fn new(a: T, b: U) -> Chain<T, U> { + Chain { + a, + b, + } + } + + /// Gets a reference to the first underlying `Buf`. + /// + /// # Examples + /// + /// ``` + /// use bytes::buf::BufExt; + /// + /// 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, buf::BufExt}; + /// + /// let mut buf = (&b"hello"[..]) + /// .chain(&b"world"[..]); + /// + /// buf.first_mut().advance(1); + /// + /// let full = buf.to_bytes(); + /// 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::BufExt; + /// + /// 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, buf::BufExt}; + /// + /// let mut buf = (&b"hello "[..]) + /// .chain(&b"world"[..]); + /// + /// buf.last_mut().advance(1); + /// + /// let full = buf.to_bytes(); + /// 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::BufExt; + /// + /// 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() + self.b.remaining() + } + + fn bytes(&self) -> &[u8] { + if self.a.has_remaining() { + self.a.bytes() + } else { + self.b.bytes() + } + } + + 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 bytes_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize { + let mut n = self.a.bytes_vectored(dst); + n += self.b.bytes_vectored(&mut dst[n..]); + n + } +} + +impl<T, U> BufMut for Chain<T, U> + where T: BufMut, + U: BufMut, +{ + fn remaining_mut(&self) -> usize { + self.a.remaining_mut() + self.b.remaining_mut() + } + + fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] { + if self.a.has_remaining_mut() { + self.a.bytes_mut() + } else { + self.b.bytes_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); + } + + #[cfg(feature = "std")] + fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize { + let mut n = self.a.bytes_vectored_mut(dst); + n += self.b.bytes_vectored_mut(&mut dst[n..]); + n + } +} + +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) + } +} |