diff --git a/library/std/src/io/impls.rs b/library/std/src/io/impls.rs index e5048dcc8acd9..1e8b718ad51f0 100644 --- a/library/std/src/io/impls.rs +++ b/library/std/src/io/impls.rs @@ -436,6 +436,24 @@ impl Read for VecDeque { } } +/// BufRead is implemented for `VecDeque` by reading bytes from the front of the `VecDeque`. +#[stable(feature = "vecdeque_buf_read", since = "CURRENT_RUSTC_VERSION")] +impl BufRead for VecDeque { + /// Returns the contents of the "front" slice as returned by + /// [`as_slices`][`VecDeque::as_slices`]. If the contained byte slices of the `VecDeque` are + /// discontiguous, multiple calls to `fill_buf` will be needed to read the entire content. + #[inline] + fn fill_buf(&mut self) -> io::Result<&[u8]> { + let (front, _) = self.as_slices(); + Ok(front) + } + + #[inline] + fn consume(&mut self, amt: usize) { + self.drain(..amt); + } +} + /// Write is implemented for `VecDeque` by appending to the `VecDeque`, growing it as needed. #[stable(feature = "vecdeque_read_write", since = "1.63.0")] impl Write for VecDeque {