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hash.rs
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hash.rs
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use minicbor::{Decode, Encode};
use std::{fmt, ops::Deref, str::FromStr};
/// data that is a cryptographic [`struct@Hash`] of `BYTES` long.
///
/// Possible values with Cardano are 32 bytes long (block hash or transaction
/// hash). Or 28 bytes long (as used in addresses)
///
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Hash<const BYTES: usize>([u8; BYTES]);
impl<const BYTES: usize> Hash<BYTES> {
#[inline]
pub const fn new(bytes: [u8; BYTES]) -> Self {
Self(bytes)
}
}
impl<const BYTES: usize> From<[u8; BYTES]> for Hash<BYTES> {
#[inline]
fn from(bytes: [u8; BYTES]) -> Self {
Self::new(bytes)
}
}
impl<const BYTES: usize> AsRef<[u8]> for Hash<BYTES> {
#[inline]
fn as_ref(&self) -> &[u8] {
&self.0
}
}
impl<const BYTES: usize> Deref for Hash<BYTES> {
type Target = [u8; BYTES];
#[inline]
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl<const BYTES: usize> PartialEq<[u8]> for Hash<BYTES> {
fn eq(&self, other: &[u8]) -> bool {
self.0.eq(other)
}
}
impl<const BYTES: usize> fmt::Debug for Hash<BYTES> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple(&format!("Hash<{size}>", size = BYTES))
.field(&hex::encode(self))
.finish()
}
}
impl<const BYTES: usize> fmt::Display for Hash<BYTES> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(&hex::encode(self))
}
}
impl<const BYTES: usize> FromStr for Hash<BYTES> {
type Err = hex::FromHexError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let mut bytes = [0; BYTES];
hex::decode_to_slice(s, &mut bytes)?;
Ok(Self::new(bytes))
}
}
impl<const BYTES: usize> Encode for Hash<BYTES> {
fn encode<W: minicbor::encode::Write>(
&self,
e: &mut minicbor::Encoder<W>,
) -> Result<(), minicbor::encode::Error<W::Error>> {
e.bytes(&self.0)?.ok()
}
}
impl<'a, const BYTES: usize> Decode<'a> for Hash<BYTES> {
fn decode(d: &mut minicbor::Decoder<'a>) -> Result<Self, minicbor::decode::Error> {
let bytes = d.bytes()?;
if bytes.len() == BYTES {
let mut hash = [0; BYTES];
hash.copy_from_slice(bytes);
Ok(Self::new(hash))
} else {
// TODO: minicbor does not allow for expecting a specific size byte array
// (in fact cbor is not good at it at all anyway)
Err(minicbor::decode::Error::Message("Invalid hash size"))
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn from_str() {
let _digest: Hash<28> = "276fd18711931e2c0e21430192dbeac0e458093cd9d1fcd7210f64b3"
.parse()
.unwrap();
let _digest: Hash<32> = "0d8d00cdd4657ac84d82f0a56067634a7adfdf43da41cb534bcaa45060973d21"
.parse()
.unwrap();
}
#[test]
#[should_panic]
fn from_str_fail_1() {
let _digest: Hash<28> = "27".parse().unwrap();
}
#[test]
#[should_panic]
fn from_str_fail_2() {
let _digest: Hash<32> = "0d8d00cdd465".parse().unwrap();
}
}