eth2_serde_utils 0.1.0

Serialization and deserialization utilities useful for JSON representations of Ethereum 2.0 types.
Documentation 
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//! Formats `[u8; 4]` as a 0x-prefixed hex string.
//!
//! E.g., `[0, 1, 2, 3]` serializes as `"0x00010203"`.

use crate::hex::PrefixedHexVisitor;
use serde::de::Error;
use serde::{Deserializer, Serializer};

const BYTES_LEN: usize = 4;

pub fn serialize<S>(bytes: &[u8; BYTES_LEN], serializer: S) -> Result<S::Ok, S::Error>
where
    S: Serializer,
{
    let mut hex_string: String = "0x".to_string();
    hex_string.push_str(&hex::encode(&bytes));

    serializer.serialize_str(&hex_string)
}

pub fn deserialize<'de, D>(deserializer: D) -> Result<[u8; BYTES_LEN], D::Error>
where
    D: Deserializer<'de>,
{
    let decoded = deserializer.deserialize_str(PrefixedHexVisitor)?;

    if decoded.len() != BYTES_LEN {
        return Err(D::Error::custom(format!(
            "expected {} bytes for array, got {}",
            BYTES_LEN,
            decoded.len()
        )));
    }

    let mut array = [0; BYTES_LEN];
    array.copy_from_slice(&decoded);
    Ok(array)
}