Source code
Revision control
Copy as Markdown
Other Tools
#[cfg(feature = "default-hasher")]
use {
core::hash::{BuildHasher, Hasher},
foldhash::fast::RandomState,
};
/// Default hash builder for the `S` type parameter of
/// [`HashMap`](crate::HashMap) and [`HashSet`](crate::HashSet).
///
/// This only implements `BuildHasher` when the "default-hasher" crate feature
/// is enabled; otherwise it just serves as a placeholder, and a custom `S` type
/// must be used to have a fully functional `HashMap` or `HashSet`.
#[derive(Clone, Debug, Default)]
pub struct DefaultHashBuilder {
#[cfg(feature = "default-hasher")]
inner: RandomState,
}
#[cfg(feature = "default-hasher")]
impl BuildHasher for DefaultHashBuilder {
type Hasher = DefaultHasher;
#[inline(always)]
fn build_hasher(&self) -> Self::Hasher {
DefaultHasher {
inner: self.inner.build_hasher(),
}
}
}
/// Default hasher for [`HashMap`](crate::HashMap) and [`HashSet`](crate::HashSet).
#[cfg(feature = "default-hasher")]
#[derive(Clone)]
pub struct DefaultHasher {
inner: <RandomState as BuildHasher>::Hasher,
}
#[cfg(feature = "default-hasher")]
macro_rules! forward_writes {
($( $write:ident ( $ty:ty ) , )*) => {$(
#[inline(always)]
fn $write(&mut self, arg: $ty) {
self.inner.$write(arg);
}
)*}
}
#[cfg(feature = "default-hasher")]
impl Hasher for DefaultHasher {
forward_writes! {
write(&[u8]),
write_u8(u8),
write_u16(u16),
write_u32(u32),
write_u64(u64),
write_u128(u128),
write_usize(usize),
write_i8(i8),
write_i16(i16),
write_i32(i32),
write_i64(i64),
write_i128(i128),
write_isize(isize),
}
// feature(hasher_prefixfree_extras)
#[cfg(feature = "nightly")]
forward_writes! {
write_length_prefix(usize),
write_str(&str),
}
#[inline(always)]
fn finish(&self) -> u64 {
self.inner.finish()
}
}