Attribute Macro binrw::parser

#[parser]

Attribute macro used to generate parse_with functions.

Rust functions are transformed by this macro to match the binrw API.

Attribute options

• #[parser(reader)] or #[parser(reader: $ident)]: Exposes the write stream to the function. If no variable name is given, reader is used.
• #[parser(endian)] or #[parser(endian: $ident)]: Exposes the endianness to the function. If no variable name is given, endian is used.

Options are comma-separated.

Function parameters

Parameters are transformed into either tuple-style arguments or raw arguments depending upon the function signature.

Tuple-style arguments

Use a normal function signature. The parameters in the signature will be converted to a tuple. For example:

#[binrw::parser(reader: r, endian)]
fn custom_parser(v0: u8, v1: i16) -> binrw::BinResult<()> {
    Ok(())
}

The transformed output for this function is:

use binrw::{BinResult, Endian, io::{Read, Seek}};
fn custom_parser<R: Read + Seek>(
    r: &mut R,
    endian: Endian,
    (v0, v1): (u8, i16)
) -> BinResult<()> {
    Ok(())
}

Raw arguments

Use a variadic function signature with a single parameter. The name and type of the parameter will be used as the raw argument. For example:

#[binrw::parser]
fn custom_parser(args: ArgsType, ...) -> binrw::BinResult<()> {
    Ok(())
}

The transformed output for this function is:

use binrw::{BinResult, Endian, io::{Read, Seek}};
fn custom_parser<R: Read + Seek>(
    _: &mut R,
    _: Endian,
    args: ArgsType
) -> BinResult<()> {
    Ok(())
}

Return value

The return value of a parser function must be BinResult<T>, where T is the type of the object being parsed.