Trait EncoderExt

pub trait EncoderExt<A, E>: Encoder<A, Error = E> {
    // Provided method
    fn contra_map<F, B>(self, f: F) -> EncoderContraMap<Self, F>
       where F: Fn(B) -> A,
             Self: Sized { ... }
}

Extension of Encoder with compositional operations.

Provided Methods

fn contra_map<F, B>(self, f: F) -> EncoderContraMap<Self, F>

where F: Fn(B) -> A, Self: Sized,

Applies a function f of type B -> A over the input before encoding.

So, if you have a value of type A for which there’s an Encoder<A>, and you have a function B -> A, then you can obtain an Encoder<B>. Notice that the arrows are “reversed” if compared against a typical map operation.

The function f cannot fail.

Examples

use tokio_util_codec_compose::{encode::EncoderExt, primitives::uint8};

struct Device(u8);

let mut dst = BytesMut::default();
let device = uint8().contra_map(|d: Device| d.0).encode(Device(0x01), &mut dst).unwrap();
assert_eq!(dst, BytesMut::from("\x01"));

Implementors

impl<C, A, E> EncoderExt<A, E> for C

where C: Encoder<A, Error = E>,