Trait Decode 

pub trait Decode {
    // Required methods
    fn read_byte(&mut self) -> Result<u8>;
    fn read_into(&mut self, out: &mut [u8]) -> Result<()>;
    fn max_alloc(&self) -> usize;

    // Provided methods
    fn read_varint_u64(&mut self) -> Result<u64> { ... }
    fn read_varint_u128(&mut self) -> Result<u128> { ... }
    fn read_length_prefixed(&mut self) -> Result<Vec<u8>> { ... }
}

Source that a Deserialize implementation reads its wire-format bytes from.

Implemented by every concrete decoder in the crate (Decoder for the in-memory case, crate::IoDecoder for std::io::Read streams). User code rarely implements Decode directly — Deserialize impls are written generically over D: Decode.

All methods are total: on any byte sequence they either succeed (advancing the cursor) or return a SerialError. They never panic, never read past the input, and never allocate more memory than Decode::max_alloc permits.

Required Methods

fn read_byte(&mut self) -> Result<u8>

Read the next byte, advancing the cursor.

Errors

Returns SerialError::UnexpectedEof if the input is exhausted. Streaming decoders MAY return an I/O-flavoured error variant.

fn read_into(&mut self, out: &mut [u8]) -> Result<()>

Fill out with exactly out.len() bytes, advancing the cursor.

Errors

Returns SerialError::UnexpectedEof on short read.

fn max_alloc(&self) -> usize

Maximum number of bytes the decoder will allocate for a single length-prefixed value. Mirrors Config::max_alloc.

Provided Methods

fn read_varint_u64(&mut self) -> Result<u64>

Read a LEB128 varint as a u64.

Errors

Returns SerialError::VarintOverflow for an overlong encoding, or SerialError::UnexpectedEof for a truncated one.

fn read_varint_u128(&mut self) -> Result<u128>

Read a LEB128 varint as a u128.

Errors

See Decode::read_varint_u64.

fn read_length_prefixed(&mut self) -> Result<Vec<u8>>

Read a length-prefixed byte run, allocating a fresh Vec<u8>.

The length is read as a varint, validated against Decode::max_alloc, then the corresponding number of bytes is read from the underlying source.

Errors

• SerialError::InvalidLength if the prefix exceeds max_alloc.
• SerialError::UnexpectedEof if the source runs out before the declared length is satisfied.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Decode for Decoder<'_>

impl<R: Read> Decode for IoDecoder<R>

Available on crate feature std only.