macro_rules! impl_write {
($hasher_struct:ty) => {
#[cfg(feature = "std")]
impl ::std::io::Write for $hasher_struct {
fn write(&mut self, bytes: &[u8]) -> ::std::io::Result<usize> {
$crate::HighwayHash::append(self, bytes);
Ok(bytes.len())
}
fn flush(&mut self) -> ::std::io::Result<()> {
Ok(())
}
}
};
}
macro_rules! impl_hasher {
($hasher_struct:ty) => {
impl ::core::hash::Hasher for $hasher_struct {
fn write(&mut self, bytes: &[u8]) {
$crate::HighwayHash::append(self, bytes);
}
fn finish(&self) -> u64 {
// Reasons why we need to clone. finalize64` mutates internal state so either we need our
// Hasher to consume itself or receive a mutable reference on `finish`. We receive neither,
// due to finish being a misnomer (additional writes could be expected) and it's intended
// for the hasher to merely return it's current state. The issue with HighwayHash is that
// there are several rounds of permutations when finalizing a value, and internal state is
// modified during that process. We work around these constraints by cloning the hasher and
// finalizing that one.
$crate::HighwayHash::finalize64(self.clone())
}
}
};
}