Trait prelude::Seek 1.0.0
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pub trait Seek { fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>; }
The Seek
trait provides a cursor which can be moved within a stream of
bytes.
The stream typically has a fixed size, allowing seeking relative to either end or the current offset.
Examples
File
s implement Seek
:
use std::io; use std::io::prelude::*; use std::fs::File; use std::io::SeekFrom; let mut f = File::open("foo.txt")?; // move the cursor 42 bytes from the start of the file f.seek(SeekFrom::Start(42))?;
Required Methods
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>
Seek to an offset, in bytes, in a stream.
A seek beyond the end of a stream is allowed, but implementation defined.
If the seek operation completed successfully,
this method returns the new position from the start of the stream.
That position can be used later with SeekFrom::Start
.
Errors
Seeking to a negative offset is considered an error.
Implementations on Foreign Types
impl<S> Seek for Box<S> where
S: Seek + ?Sized,
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S: Seek + ?Sized,
impl<T> Seek for Cursor<T> where
T: AsRef<[u8]>,
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T: AsRef<[u8]>,
impl<R> Seek for BufReader<R> where
R: Seek,
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R: Seek,
fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>
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Seek to an offset, in bytes, in the underlying reader.
The position used for seeking with SeekFrom::Current(_)
is the
position the underlying reader would be at if the BufReader
had no
internal buffer.
Seeking always discards the internal buffer, even if the seek position
would otherwise fall within it. This guarantees that calling
.into_inner()
immediately after a seek yields the underlying reader
at the same position.
See std::io::Seek
for more details.
Note: In the edge case where you're seeking with SeekFrom::Current(n)
where n
minus the internal buffer length underflows an i64
, two
seeks will be performed instead of one. If the second seek returns
Err
, the underlying reader will be left at the same position it would
have if you seeked to SeekFrom::Current(0)
.
impl<W> Seek for BufWriter<W> where
W: Write + Seek,
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W: Write + Seek,
impl<'a, S> Seek for &'a mut S where
S: Seek + ?Sized,
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S: Seek + ?Sized,