cuprate_types/
hex.rs

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1//! Hexadecimal serde wrappers for arrays.
2//!
3//! This module provides transparent wrapper types for
4//! arrays that (de)serialize from hexadecimal input/output.
5
6#[cfg(feature = "epee")]
7use cuprate_epee_encoding::{error, macros::bytes, EpeeValue, Marker};
8#[cfg(feature = "serde")]
9use serde::{Deserialize, Serialize};
10
11/// Wrapper type for a byte array that (de)serializes from/to hexadecimal strings.
12///
13/// # Deserialization
14/// This struct has a custom deserialization that only applies to certain
15/// `N` lengths because [`hex::FromHex`] does not implement for a generic `N`:
16/// <https://docs.rs/hex/0.4.3/src/hex/lib.rs.html#220-230>
17#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
18#[cfg_attr(feature = "serde", derive(Serialize))]
19#[cfg_attr(feature = "serde", serde(transparent))]
20#[repr(transparent)]
21pub struct HexBytes<const N: usize>(
22    #[cfg_attr(feature = "serde", serde(with = "hex::serde"))] pub [u8; N],
23);
24
25#[cfg(feature = "serde")]
26impl<'de, const N: usize> Deserialize<'de> for HexBytes<N>
27where
28    [u8; N]: hex::FromHex,
29    <[u8; N] as hex::FromHex>::Error: std::fmt::Display,
30{
31    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
32    where
33        D: serde::Deserializer<'de>,
34    {
35        Ok(Self(hex::serde::deserialize(deserializer)?))
36    }
37}
38
39#[cfg(feature = "epee")]
40impl<const N: usize> EpeeValue for HexBytes<N> {
41    const MARKER: Marker = <[u8; N] as EpeeValue>::MARKER;
42
43    fn read<B: bytes::Buf>(r: &mut B, marker: &Marker) -> error::Result<Self> {
44        Ok(Self(<[u8; N] as EpeeValue>::read(r, marker)?))
45    }
46
47    fn write<B: bytes::BufMut>(self, w: &mut B) -> error::Result<()> {
48        <[u8; N] as EpeeValue>::write(self.0, w)
49    }
50}
51
52// Default is not implemented for arrays >32, so we must do it manually.
53impl<const N: usize> Default for HexBytes<N> {
54    fn default() -> Self {
55        Self([0; N])
56    }
57}
58
59#[cfg(test)]
60mod test {
61    use super::*;
62
63    #[test]
64    fn hex_bytes_32() {
65        let hash = [1; 32];
66        let hex_bytes = HexBytes::<32>(hash);
67        let expected_json = r#""0101010101010101010101010101010101010101010101010101010101010101""#;
68
69        let to_string = serde_json::to_string(&hex_bytes).unwrap();
70        assert_eq!(to_string, expected_json);
71
72        let from_str = serde_json::from_str::<HexBytes<32>>(expected_json).unwrap();
73        assert_eq!(hex_bytes, from_str);
74    }
75}
cuprate_types/hex.rs

cuprate_types/
hex.rs
