[−][src]Struct rev_buf_reader::RevBufReader
RevBufReader<R>
is a struct similar to std::io::BufReader<R>
, which adds
buffering to any reader. But unlike BufReader<R>
, RevBufReader<R>
reads a
data stream from the end to the start. The order of the bytes, however,
remains the same. For example, when using RevBufReader<R>
to read a text file,
we can read the same lines as we would by using BufReader<R>
, but starting
from the last line until we get to the first one.
In order to able to read a data stream in reverse order, it must implement
both std::io::Read
and std::io::Seek
.
Examples
use rev_buf_reader::RevBufReader; use std::io::prelude::*; use std::fs::File; fn main() -> std::io::Result<()> { let f = File::open("log.txt")?; let mut reader = RevBufReader::new(f); let mut line = String::new(); let len = reader.read_line(&mut line)?; println!("Last line is {} bytes long", len); Ok(()) }
Methods
impl<R: Read + Seek> RevBufReader<R>
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ⓘImportant traits for RevBufReader<R>pub fn new(inner: R) -> RevBufReader<R>
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Creates a new RevBufReader<R>
with a default buffer capacity. The default is currently 8 KB,
but may change in the future.
Examples
use rev_buf_reader::RevBufReader; use std::fs::File; fn main() -> std::io::Result<()> { let f = File::open("log.txt")?; let reader = RevBufReader::new(f); Ok(()) }
ⓘImportant traits for RevBufReader<R>pub fn with_capacity(capacity: usize, inner: R) -> RevBufReader<R>
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Creates a new RevBufReader<R>
with the specified buffer capacity.
Examples
Creating a buffer with ten bytes of capacity:
use rev_buf_reader::RevBufReader; use std::fs::File; fn main() -> std::io::Result<()> { let f = File::open("log.txt")?; let reader = RevBufReader::with_capacity(10, f); Ok(()) }
impl<R> RevBufReader<R>
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pub fn get_ref(&self) -> &R
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Gets a reference to the underlying reader.
It is inadvisable to directly read from the underlying reader.
Examples
use rev_buf_reader::RevBufReader; use std::fs::File; fn main() -> std::io::Result<()> { let f1 = File::open("log.txt")?; let reader = RevBufReader::new(f1); let f2 = reader.get_ref(); Ok(()) }
pub fn get_mut(&mut self) -> &mut R
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Gets a mutable reference to the underlying reader.
It is inadvisable to directly read from the underlying reader.
Examples
use rev_buf_reader::RevBufReader; use std::fs::File; fn main() -> std::io::Result<()> { let f1 = File::open("log.txt")?; let mut reader = RevBufReader::new(f1); let f2 = reader.get_mut(); Ok(()) }
pub fn buffer(&self) -> &[u8]
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Returns a reference to the internally buffered data.
Unlike fill_buf
, this will not attempt to fill the buffer if it is empty.
Examples
use rev_buf_reader::RevBufReader; use std::io::BufRead; use std::fs::File; fn main() -> std::io::Result<()> { let f = File::open("log.txt")?; let mut reader = RevBufReader::new(f); assert!(reader.buffer().is_empty()); if reader.fill_buf()?.len() > 0 { assert!(!reader.buffer().is_empty()); } Ok(()) }
pub fn into_inner(self) -> R
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Unwraps this RevBufReader<R>
, returning the underlying reader.
Note that any leftover data in the internal buffer is lost. Therefore, a following read from the underlying reader may lead to data loss.
Examples
use rev_buf_reader::RevBufReader; use std::fs::File; fn main() -> std::io::Result<()> { let f1 = File::open("log.txt")?; let reader = RevBufReader::new(f1); let f2 = reader.into_inner(); Ok(()) }
impl<R: Seek> RevBufReader<R>
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pub fn seek_relative(&mut self, offset: i64) -> Result<()>
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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.
Trait Implementations
impl<R: Read + Seek> BufRead for RevBufReader<R>
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fn fill_buf(&mut self) -> Result<&[u8]>
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fn consume(&mut self, amt: usize)
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fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>
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fn read_line(&mut self, buf: &mut String) -> Result<usize>
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fn split(self, byte: u8) -> Split<Self>
1.0.0[src]
fn lines(self) -> Lines<Self>
1.0.0[src]
impl<R> Debug for RevBufReader<R> where
R: Debug,
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R: Debug,
impl<R: Read + Seek> Read for RevBufReader<R>
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fn read(&mut self, buf: &mut [u8]) -> Result<usize>
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fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> Result<usize>
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unsafe fn initializer(&self) -> Initializer
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fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>
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fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>
1.0.0[src]
fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>
1.6.0[src]
fn by_ref(&mut self) -> &mut Self
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fn bytes(self) -> Bytes<Self>
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fn chain<R>(self, next: R) -> Chain<Self, R> where
R: Read,
1.0.0[src]
R: Read,
fn take(self, limit: u64) -> Take<Self>
1.0.0[src]
impl<R: Seek> Seek for RevBufReader<R>
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fn seek(&mut self, pos: SeekFrom) -> Result<u64>
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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 RevBufReader<R>
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.
To seek without discarding the internal buffer, use RevBufReader::seek_relative
.
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 overflows 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 called seek
with SeekFrom::Current(0)
.
fn stream_len(&mut self) -> Result<u64, Error>
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fn stream_position(&mut self) -> Result<u64, Error>
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Auto Trait Implementations
impl<R> RefUnwindSafe for RevBufReader<R> where
R: RefUnwindSafe,
R: RefUnwindSafe,
impl<R> Send for RevBufReader<R> where
R: Send,
R: Send,
impl<R> Sync for RevBufReader<R> where
R: Sync,
R: Sync,
impl<R> Unpin for RevBufReader<R> where
R: Unpin,
R: Unpin,
impl<R> UnwindSafe for RevBufReader<R> where
R: UnwindSafe,
R: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,