Struct LimitReader 

pub struct LimitReader<R> { /* private fields */ }

Reader wrapper that exposes at most a fixed number of bytes.

LimitReader is useful when a parser must consume a bounded section of a larger stream without relying on the caller to provide a pre-sliced buffer. Once the remaining limit reaches zero, reads return Ok(0) without touching the inner reader.

Examples

use std::io::{
    Cursor,
    Read,
};

use qubit_io::LimitReader;

let mut reader = LimitReader::new(Cursor::new(b"abcdef"), 3);
let mut data = Vec::new();
reader.read_to_end(&mut data)?;

assert_eq!(b"abc", data.as_slice());
assert_eq!(0, reader.remaining());

Implementations

impl<R> LimitReader<R>

pub fn new(inner: R, limit: u64) -> Self

Creates a reader that exposes at most limit bytes from inner.

Parameters

• inner: Reader to wrap.
• limit: Maximum number of bytes that may be read through this wrapper.

Returns

A new limited reader.

pub fn remaining(&self) -> u64

Returns the number of bytes still available through this wrapper.

Returns

Remaining readable byte count before the wrapper reports EOF.

pub fn get_ref(&self) -> &R

Returns an immutable reference to the wrapped reader.

Returns

The wrapped reader reference.

pub fn get_mut(&mut self) -> &mut R

Returns a mutable reference to the wrapped reader.

Returns

The wrapped reader reference.

pub fn into_inner(self) -> R

Consumes this wrapper and returns the wrapped reader.

Returns

The wrapped reader.

Trait Implementations

impl<R> BufRead for LimitReader<R>

where R: BufRead,

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, amount: 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> Read for LimitReader<R>

where R: Read,

fn read(&mut self, buffer: &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” adapter 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.

fn read_array<const N: usize>(&mut self) -> Result<[u8; N], Error>

where Self: Sized,

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

Read and return a fixed array of bytes from this source.