Trait Source

Source

pub trait Source {
    // Required methods
    fn read_bits(&mut self, n: u32) -> Result<u128, BitError>;
    fn bit_pos(&self) -> usize;

    // Provided methods
    fn byte_order(&self) -> ByteOrder { ... }
    fn seek_to_bit(&mut self, _pos: usize) -> Result<(), BitError> { ... }
    fn read<T: Bits>(&mut self) -> Result<T, BitError> { ... }
    fn as_read(&mut self) -> SourceReader<'_, Self> ⓘ
       where Self: Sized { ... }
}

Expand description

A bit-level input the codec recurses over. Implemented by BitReader (in-memory slice), StreamBitReader (forward Read), BufSource (a retain-and-seek socket adapter), and SeekReader (Read + Seek); the codec is generic over Source, so one decoder runs over any of them — see guide::io.

§Examples

use bnb::{BitReader, Source, u4};

// A reader generic over any `Source`.
fn first_nibble<S: Source>(s: &mut S) -> u4 { s.read().unwrap() }

let mut r = BitReader::new(&[0xA5]);
assert_eq!(first_nibble(&mut r), u4::new(0xA));

Required Methods§

Source

fn read_bits(&mut self, n: u32) -> Result<u128, BitError>

Reads n (<= 128) bits MSB-first into the low bits of a u128.

§Errors

Propagates the reader’s BitError.

Source

fn bit_pos(&self) -> usize

The current absolute bit offset (for position-aware errors).

Provided Methods§

Source

fn byte_order(&self) -> ByteOrder

The byte order applied to a byte-multiple value (default big-endian).

Source

fn seek_to_bit(&mut self, _pos: usize) -> Result<(), BitError>

Moves the cursor to absolute bit pos. The default — for a forward-only source — fails with ErrorKind::NotSeekable; seekable sources (the slice BitReader) override it. A SeekSource guarantees this works.

§Errors

ErrorKind::NotSeekable unless the source is seekable.

Source

fn read<T: Bits>(&mut self) -> Result<T, BitError>

Reads one Bits value of its declared width, applying the byte order.

§Errors

As read_bits.

Source

fn as_read(&mut self) -> SourceReader<'_, Self> ⓘ
where Self: Sized,

Borrows this source as a std::io::Read over its bytes — for handing the cursor to std::io-based code from a #[br(parse_with = …)] (e.g. a decoder, or a Read-based parser). Reads 8 bits per byte; see SourceReader. Only with the std feature.