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use std::hash::Hasher;
use std::iter::Extend;
use libc::size_t;
extern "C" {
fn Hash64(s: *const u8, len: size_t) -> u64;
fn Hash64WithSeed(s: *const u8, len: size_t, seed: u64) -> u64;
}
fn hash_64(input: &[u8]) -> u64 {
unsafe { Hash64(input.as_ptr(), input.len() as size_t) }
}
fn hash_64_with_seed(input: &[u8], seed: u64) -> u64 {
unsafe { Hash64WithSeed(input.as_ptr(), input.len() as size_t, seed) }
}
#[derive(Debug, Default)]
pub struct Hash64 {
buf: Vec<u8>,
seed: Option<u64>,
}
impl Hash64 {
pub fn with_seed(seed: u64) -> Hash64 {
Hash64 {
buf: Default::default(),
seed: Some(seed),
}
}
}
impl Hasher for Hash64 {
fn write(&mut self, bytes: &[u8]) {
self.buf.extend(bytes);
}
fn finish(&self) -> u64 {
if let Some(s) = self.seed {
hash_64_with_seed(&self.buf, s)
} else {
hash_64(&self.buf)
}
}
}
#[cfg(test)]
mod tests {
use std::hash::Hasher;
use super::Hash64;
#[test]
fn no_seed_64() {
const EXPECTED: u64 = 18084869015357591102;
let mut h = Hash64::default();
h.write(b"farmhash");
assert_eq!(EXPECTED, h.finish());
}
#[test]
fn seed_64() {
const EXPECTED: u64 = 15795874029479571151;
let mut h = Hash64::with_seed(7);
h.write(b"farmhash");
assert_eq!(EXPECTED, h.finish());
}
}