Struct EncBuf

pub struct EncBuf { /* private fields */ }

Implements right_encode and left_encode.

Implementations

impl EncBuf

pub const fn new() -> Self

Creates a new EncBuf.

pub fn encode_string<'a, 'b>(&'a mut self, s: &'b [u8]) -> EncodedString<'a>

where 'b: 'a,

Encodes s such that it can be unambiguously encoded from the beginning.

use tuple_hash::EncBuf;

let mut b = EncBuf::new();
let s = b.encode_string(b"hello, world!");
assert_eq!(
    s.flatten().copied().collect::<Vec<_>>(),
    &[
        1, 104,
        104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33,
    ],
);

pub fn left_encode(&mut self, x: usize) -> &[u8]

Encodes x as a byte string in a way that can be unambiguously parsed from the beginning.

pub fn left_encode_bytes(&mut self, x: usize) -> &[u8]

Encodes x*8 as a byte string in a way that can be unambiguously parsed from the beginning.

Rationale

left_encode is typically used to encode a length in bits. In practice, we usually have a length in bytes. The conversion from bytes to bits might overflow if the number of bytes is large. This method avoids overflowing.

Example

use tuple_hash::EncBuf;

assert_eq!(
    EncBuf::new().left_encode(8192 * 8),
    EncBuf::new().left_encode_bytes(8192),
);

// usize::MAX*8 overflows, causing an incorrect result.
assert_ne!(
    EncBuf::new().left_encode(usize::MAX.wrapping_mul(8)),
    EncBuf::new().left_encode_bytes(usize::MAX),
);

pub fn right_encode(&mut self, x: usize) -> &[u8]

Encodes x as a byte string in a way that can be unambiguously parsed from the end.

pub fn right_encode_bytes(&mut self, x: usize) -> &[u8]

Encodes x*8 as a byte string in a way that can be unambiguously parsed from the beginning.

Rationale

right_encode is typically used to encode a length in bits. In practice, we usually have a length in bytes. The conversion from bytes to bits might overflow if the number of bytes is large. This method avoids overflowing.

Example

use tuple_hash::EncBuf;

assert_eq!(
    EncBuf::new().right_encode(8192 * 8),
    EncBuf::new().right_encode_bytes(8192),
);

// usize::MAX*8 overflows, causing an incorrect result.
assert_ne!(
    EncBuf::new().right_encode(usize::MAX.wrapping_mul(8)),
    EncBuf::new().right_encode_bytes(usize::MAX),
);

Trait Implementations

impl Clone for EncBuf

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EncBuf

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

Formats the value using the given formatter.

impl Default for EncBuf

fn default() -> Self

Returns the “default value” for a type.

impl Copy for EncBuf