Struct EnsuredBufReader

pub struct EnsuredBufReader<R, B>
where
    R: Read,
    B: AsRef<[u8]> + AsMut<[u8]>,
{ /* private fields */ }

A BufReader that ensures ensured bytes in buffer.

EnsuredBufReader keeps ensured bytes in buffer if it can read from underlying reader. To fetch bytes into buffer, call fill_buf().

Implementations

impl<R: Read> EnsuredBufReader<R, Vec<u8>>

pub fn new(inner: R) -> EnsuredBufReader<R, Vec<u8>>

Creates a new EnsuredBufReader with a default capacity (DEFAULT_BUFFER_SIZE) and a default ensured size (DEFAULT_ENSURED_BYTES).

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let r = EnsuredBufReader::new(f);
    Ok(())
}

pub fn with_capacity_and_ensured_size( capacity: usize, ensured_size: usize, inner: R, ) -> EnsuredBufReader<R, Vec<u8>>

Creates a new EnsuredBufReader with a specified capacity and ensured_size.

capacity must be larger than or equal to ensured_size. ensured_size must be positive.

Panics

Panics if capacity is smaller than ensured_size. Panics if ensured_size is 0.

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let r = EnsuredBufReader::with_capacity_and_ensured_size(1024, 32, f);
    Ok(())
}

impl<R: Read> EnsuredBufReader<R, &mut [u8]>

pub fn from_mut_ref(buf: &mut [u8], inner: R) -> EnsuredBufReader<R, &mut [u8]>

Creates a new EnsuredBufReader with given buffer.

Buffer length must be larger than or equal to DEFAULT_ENSURED_BYTES.

Panics

Panics if buffer is smaller than DEFAULT_ENSURED_BYTES.

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let mut buf = [0u8; 1024];
    let r = EnsuredBufReader::from_mut_ref(&mut buf, f);
    Ok(())
}

pub fn from_mut_ref_and_ensured_size( buf: &mut [u8], ensured_size: usize, inner: R, ) -> EnsuredBufReader<R, &mut [u8]>

Creates a new EnsuredBufReader with given buffer and a specified ensured_size.

Buffer length must be larger than or equal to ensured_size. ensured_size must be positive.

Panics

Panics if buffer is smaller than ensured_size. Panics if ensured_size is 0.

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let mut buf = [0u8; 1024];
    let r = EnsuredBufReader::from_mut_ref_and_ensured_size(&mut buf, 32, f);
    Ok(())
}

impl<R: Read, B: AsRef<[u8]> + AsMut<[u8]>> EnsuredBufReader<R, B>

pub fn from_buffer(buf: B, inner: R) -> EnsuredBufReader<R, B>

Creates a new EnsuredBufReader with given buffer.

Buffer length must be larger than or equal to DEFAULT_ENSURED_BYTES.

Panics

Panics if buffer is smaller than DEFAULT_ENSURED_BYTES.

pub fn from_buffer_and_ensured_size( buf: B, ensured_size: usize, inner: R, ) -> EnsuredBufReader<R, B>

Creates a new EnsuredBufReader with given buffer and a specified ensured_size.

Buffer length must be larger than or equal to ensured_size. ensured_size must be positive.

Panics

Panics if buffer is smaller than ensured_size. Panics if ensured_size is 0.

pub fn buffer(&self) -> &[u8]

Returns a reference to current buffer. This method doesn’t read bytes from underlying reader.

Examples

use std::fs::File;
use std::io::{self, BufRead};
use ensured_bufreader::EnsuredBufReader;

fn main() -> io::Result<()> {
    let f = File::open("README.md")?;
    let mut r = EnsuredBufReader::new(f);

    // Read bytes from file and consume 8 bytes.
    let read_bytes = r.fill_buf()?.to_owned();
    r.consume(8);
     
    // Get buffer.
    // Current buffer should be　8 bytes shorter than `read_bytes`.
    let buf = r.buffer();
    assert_eq!(buf, &read_bytes[8..]);

    Ok(())
}

pub fn fill_buf_to_expected_size( &mut self, expected_size: usize, ) -> Result<&[u8]>

Try to fill buffer and return reference to buffer. The buffer filled at least expected_size bytes if EnsuredBufReader could read from underlying reader.

Errors

Returns error that has .kind() == ErrorKind::InvalidInput if expected_size is larger than capacity.

Examples

The buffer will be filled to expected_size.

use std::fs::File;
use std::io::{self, BufRead};
use ensured_bufreader::EnsuredBufReader;

fn main() -> io::Result<()> {
    let f = File::open("README.md")?;
    let mut r = EnsuredBufReader::with_capacity_and_ensured_size(1024, 1, f);

    // Fill buffer.
    let read_bytes = r.fill_buf_to_expected_size(512)?;
    assert!(read_bytes.len() >= 512);

    Ok(())
}

If expected_size is larger than capacity, error will be returned.

use std::fs::File;
use std::io::{self, BufRead, ErrorKind};
use ensured_bufreader::EnsuredBufReader;

fn main() -> io::Result<()> {
    let f = File::open("README.md")?;
    let mut r = EnsuredBufReader::with_capacity_and_ensured_size(512, 1, f);

    let err = r.fill_buf_to_expected_size(513).unwrap_err();
    assert_eq!(err.kind(), ErrorKind::InvalidInput);

    Ok(())
}

pub fn get_capacity(&self) -> usize

Get current capacity size.

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let r = EnsuredBufReader::new(f);

    assert_eq!(r.get_capacity(), 8192);
    Ok(())
}

pub fn get_ensured_size(&self) -> usize

Get current ensured size.

Examples

use std::fs::File;
use ensured_bufreader::EnsuredBufReader;

fn main() -> std::io::Result<()> {
    let f = File::open("README.md")?;
    let r = EnsuredBufReader::new(f);

    assert_eq!(r.get_ensured_size(), 128);
    Ok(())
}

pub fn current_bytes(&self) -> usize

Returns count of bytes in buffer.

Trait Implementations

impl<R: Read, B: AsRef<[u8]> + AsMut<[u8]>> BufRead for EnsuredBufReader<R, B>

fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data, via Read methods, if empty.

fn consume(&mut self, amt: usize)

Marks the given amount of additional bytes from the internal buffer as having been read. Subsequent calls to read only return bytes that have not been marked as read.

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

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

Checks if there is any data left to be read.

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

Reads all bytes into buf until the delimiter byte or EOF is reached.

fn skip_until(&mut self, byte: u8) -> Result<usize, Error>

Skips all bytes until the delimiter byte or EOF is reached.

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

Reads all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer.

fn split(self, byte: u8) -> Split<Self>

where Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte.

fn lines(self) -> Lines<Self>

where Self: Sized,

Returns an iterator over the lines of this reader.

impl<R, B> Debug for EnsuredBufReader<R, B>

where R: Read + Debug, B: AsRef<[u8]> + AsMut<[u8]>,

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<R: Read, B: AsRef<[u8]> + AsMut<[u8]>> Read for EnsuredBufReader<R, B>

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

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

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.

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

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

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

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

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

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Reads the exact number of bytes required to fill cursor.

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

where Self: Sized,

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

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

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

where Self: Sized,

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