src/test/run-pass/deriving-hash.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11
  12 #![feature(hash_default)]
  13
  14 use std::hash::{Hash, SipHasher, Hasher};
  15 use std::mem::size_of;
  16
  17 #[derive(Hash)]
  18 struct Person {
  19     id: usize,
  20     name: String,
  21     phone: usize,
  22 }
  23
  24 // test for hygiene name collisions
  25 #[derive(Hash)] struct __H__H;
  26 #[derive(Hash)] enum Collision<__H> { __H { __H__H: __H } }
  27
  28 #[derive(Hash)]
  29 enum E { A=1, B }
  30
  31 fn hash<T: Hash>(t: &T) -> u64 {
  32     let mut s = SipHasher::new_with_keys(0, 0);
  33     t.hash(&mut s);
  34     s.finish()
  35 }
  36
  37 struct FakeHasher<'a>(&'a mut Vec<u8>);
  38 impl<'a> Hasher for FakeHasher<'a> {
  39     fn finish(&self) -> u64 {
  40         unimplemented!()
  41     }
  42
  43     fn write(&mut self, bytes: &[u8]) {
  44         self.0.extend(bytes);
  45     }
  46 }
  47
  48 fn fake_hash(v: &mut Vec<u8>, e: E) {
  49     e.hash(&mut FakeHasher(v));
  50 }
  51
  52 fn main() {
  53     let person1 = Person {
  54         id: 5,
  55         name: "Janet".to_string(),
  56         phone: 555_666_7777
  57     };
  58     let person2 = Person {
  59         id: 5,
  60         name: "Bob".to_string(),
  61         phone: 555_666_7777
  62     };
  63     assert_eq!(hash(&person1), hash(&person1));
  64     assert!(hash(&person1) != hash(&person2));
  65
  66     // test #21714
  67     let mut va = vec![];
  68     let mut vb = vec![];
  69     fake_hash(&mut va, E::A);
  70     fake_hash(&mut vb, E::B);
  71     assert!(va != vb);
  72 }