diff options
| -rw-r--r-- | library/std/src/io/buffered/bufreader.rs | 10 | ||||
| -rw-r--r-- | library/std/src/io/mod.rs | 30 |
2 files changed, 40 insertions, 0 deletions
diff --git a/library/std/src/io/buffered/bufreader.rs b/library/std/src/io/buffered/bufreader.rs index 55aafc3db33..6c7494a6a6f 100644 --- a/library/std/src/io/buffered/bufreader.rs +++ b/library/std/src/io/buffered/bufreader.rs @@ -507,6 +507,16 @@ impl<R: ?Sized + Seek> Seek for BufReader<R> { ) }) } + + /// Seeks relative to the current position. + /// + /// If the new position lies within the buffer, the buffer will not be + /// flushed, allowing for more efficient seeks. This method does not return + /// the location of the underlying reader, so the caller must track this + /// information themselves if it is required. + fn seek_relative(&mut self, offset: i64) -> io::Result<()> { + self.seek_relative(offset) + } } impl<T: ?Sized> SizeHint for BufReader<T> { diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs index 7d70a0bac24..ff5b4e76d44 100644 --- a/library/std/src/io/mod.rs +++ b/library/std/src/io/mod.rs @@ -1957,6 +1957,36 @@ pub trait Seek { fn stream_position(&mut self) -> Result<u64> { self.seek(SeekFrom::Current(0)) } + + /// Seeks relative to the current position. + /// + /// This is equivalent to `self.seek(SeekFrom::Current(offset))` but + /// doesn't return the new position which can allow some implementations + /// such as [`BufReader`] to perform more efficient seeks. + /// + /// # Example + /// + /// ```no_run + /// #![feature(seek_seek_relative)] + /// use std::{ + /// io::{self, Seek}, + /// fs::File, + /// }; + /// + /// fn main() -> io::Result<()> { + /// let mut f = File::open("foo.txt")?; + /// f.seek_relative(10)?; + /// assert_eq!(f.stream_position()?, 10); + /// Ok(()) + /// } + /// ``` + /// + /// [`BufReader`]: crate::io::BufReader + #[unstable(feature = "seek_seek_relative", issue = "117374")] + fn seek_relative(&mut self, offset: i64) -> Result<()> { + self.seek(SeekFrom::Current(offset))?; + Ok(()) + } } /// Enumeration of possible methods to seek within an I/O object. |
