Struct seekable_reader::SeekableReader

pub struct SeekableReader<R: Read> {
    pub inner: R,
    pub keep_size: usize,
    pub read_bytes: usize,
    // some fields omitted
}

A reader adapter that allows to seek a little bit

The SeekableReader will wrap around a Read instance and can be read normally. The core feature is to provide Seek, even if the underlying Reader does not. It achieves this by holding a cache of the read data, which can be read again.

Fields

inner: R

keep_size: usize

read_bytes: usize

Bytes read from inner

Implementations

impl<R: Read> SeekableReader<R>

pub fn new(inner: R, keep_size: usize) -> SeekableReader<R>

Create a new instance of a SeekableReader.

It wraps around inner and allows seeking backwards by keeping at least keep_size bytes of already read data, if this amount of data is already read.

At most, 2 * keep_size bytes are kept.

pub fn buffered_size(&self) -> usize

Returns the size of the buffered data. Attempts to seek further back will result an Error.

pub fn get_stream_position(&self) -> usize

Trait Implementations

impl<R: Read> Read for SeekableReader<R>

A SeekableReader can be read just normally:

use std::io::Read;
use seekable_reader::SeekableReader;

let source = vec![1, 2, 3, 4, 5];
let reader = SeekableReader::new(source.as_slice(), 1);
let bytes: Vec<_> = reader.bytes().map(|b| b.unwrap()).collect();
assert_eq!(&source, &bytes);

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Read something from this source and write it into buffer, returning how many bytes were read.

read will never read more than buf.len() from the underlying reader. But it may have read less than it returns, in case the user seeked backwards before, causing the cache to be used.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

fn by_ref(&mut self) -> &mut Self

Creates a “by reference” adapter for this instance of Read.

fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

Creates an adapter which will read at most limit bytes from it.

impl<R: Read> Seek for SeekableReader<R>

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

fn stream_len(&mut self) -> Result<u64, Error>

🔬 This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.