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