/
lib.rs
140 lines (124 loc) · 3.04 KB
/
lib.rs
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#![feature(hash, no_std)]
#![cfg_attr(feature = "core", feature(core))]
#![no_std]
#![doc(html_root_url="http://sfackler.github.io/rust-phf/doc")]
#[cfg(feature = "core")]
extern crate core;
#[cfg(not(feature = "core"))]
extern crate std;
use std::slice::AsSlice;
use std::str::StrExt;
use std::hash::{Writer, Hasher, Hash, SipHasher};
#[cfg(feature = "core")]
mod std {
pub use core::{slice, str, hash};
}
#[inline]
pub fn displace(f1: u32, f2: u32, d1: u32, d2: u32) -> u32 {
d2 + f1 * d1 + f2
}
#[inline]
fn split(hash: u64) -> (u32, u32, u32) {
const BITS: u32 = 21;
const MASK: u64 = (1 << BITS) - 1;
((hash & MASK) as u32,
((hash >> BITS) & MASK) as u32,
((hash >> (2 * BITS)) & MASK) as u32)
}
/// A trait implemented by types which can be used in PHF data structures
pub trait PhfHash {
/// Hashes the value of `self`, factoring in a seed
fn phf_hash(&self, seed: u64) -> (u32, u32, u32);
}
impl<'a> PhfHash for &'a str {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
self.as_bytes().phf_hash(seed)
}
}
impl<'a> PhfHash for &'a [u8] {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
(*self).phf_hash(seed)
}
}
impl PhfHash for str {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
self.as_bytes().phf_hash(seed)
}
}
impl PhfHash for [u8] {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
let mut state = SipHasher::new_with_keys(seed, 0);
state.write(self);
split(state.finish())
}
}
macro_rules! sip_impl(
($t:ty) => (
impl PhfHash for $t {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
let mut hasher = SipHasher::new_with_keys(seed, 0);
self.hash(&mut hasher);
split(hasher.finish())
}
}
)
);
sip_impl!(u8);
sip_impl!(i8);
sip_impl!(u16);
sip_impl!(i16);
sip_impl!(u32);
sip_impl!(i32);
sip_impl!(u64);
sip_impl!(i64);
sip_impl!(char);
sip_impl!(bool);
macro_rules! array_impl(
($t:ty, $n:expr) => (
impl PhfHash for [$t; $n] {
#[inline]
fn phf_hash(&self, seed: u64) -> (u32, u32, u32) {
let mut hasher = SipHasher::new_with_keys(seed, 0);
hasher.write(self.as_slice());
split(hasher.finish())
}
}
)
);
array_impl!(u8, 1);
array_impl!(u8, 2);
array_impl!(u8, 3);
array_impl!(u8, 4);
array_impl!(u8, 5);
array_impl!(u8, 6);
array_impl!(u8, 7);
array_impl!(u8, 8);
array_impl!(u8, 9);
array_impl!(u8, 10);
array_impl!(u8, 11);
array_impl!(u8, 12);
array_impl!(u8, 13);
array_impl!(u8, 14);
array_impl!(u8, 15);
array_impl!(u8, 16);
array_impl!(u8, 17);
array_impl!(u8, 18);
array_impl!(u8, 19);
array_impl!(u8, 20);
array_impl!(u8, 21);
array_impl!(u8, 22);
array_impl!(u8, 23);
array_impl!(u8, 24);
array_impl!(u8, 25);
array_impl!(u8, 26);
array_impl!(u8, 27);
array_impl!(u8, 28);
array_impl!(u8, 29);
array_impl!(u8, 30);
array_impl!(u8, 31);
array_impl!(u8, 32);