103 lines
2.6 KiB
Rust
103 lines
2.6 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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* Generic hashing support.
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*
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* This module provides a generic way to compute the hash of a value. The
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* simplest way to make a type hashable is to use `#[deriving(Hash)]`:
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*
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* # Example
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*
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* ```rust
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* use std::hash;
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* use std::hash::Hash;
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*
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* #[deriving(Hash)]
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* struct Person {
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* id: uint,
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* name: String,
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* phone: u64,
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* }
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*
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* let person1 = Person { id: 5, name: "Janet".to_string(), phone: 555_666_7777 };
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* let person2 = Person { id: 5, name: "Bob".to_string(), phone: 555_666_7777 };
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*
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* assert!(hash::hash(&person1) != hash::hash(&person2));
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* ```
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*
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* If you need more control over how a value is hashed, you need to implement
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* the trait `Hash`:
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*
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* ```rust
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* use std::hash;
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* use std::hash::Hash;
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* use std::hash::sip::SipState;
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*
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* struct Person {
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* id: uint,
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* name: String,
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* phone: u64,
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* }
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*
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* impl Hash for Person {
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* fn hash(&self, state: &mut SipState) {
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* self.id.hash(state);
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* self.phone.hash(state);
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* }
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* }
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*
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* let person1 = Person { id: 5, name: "Janet".to_string(), phone: 555_666_7777 };
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* let person2 = Person { id: 5, name: "Bob".to_string(), phone: 555_666_7777 };
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*
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* assert!(hash::hash(&person1) == hash::hash(&person2));
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* ```
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*/
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pub use core_collections::hash::{Hash, Hasher, Writer, hash, sip};
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use default::Default;
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use rand::Rng;
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use rand;
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/// `RandomSipHasher` computes the SipHash algorithm from a stream of bytes
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/// initialized with random keys.
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#[deriving(Clone)]
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pub struct RandomSipHasher {
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hasher: sip::SipHasher,
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}
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impl RandomSipHasher {
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/// Construct a new `RandomSipHasher` that is initialized with random keys.
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#[inline]
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pub fn new() -> RandomSipHasher {
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let mut r = rand::task_rng();
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let r0 = r.gen();
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let r1 = r.gen();
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RandomSipHasher {
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hasher: sip::SipHasher::new_with_keys(r0, r1),
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}
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}
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}
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impl Hasher<sip::SipState> for RandomSipHasher {
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#[inline]
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fn hash<T: Hash<sip::SipState>>(&self, value: &T) -> u64 {
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self.hasher.hash(value)
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}
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}
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impl Default for RandomSipHasher {
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#[inline]
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fn default() -> RandomSipHasher {
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RandomSipHasher::new()
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}
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}
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