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[rustc.git] / src / libstd / collections / hash / state.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 #![unstable(feature = "hashmap_hasher", reason = "hasher stuff is unclear",
12 issue = "27713")]
13 #![rustc_deprecated(since = "1.7.0", reason = "support moved to std::hash")]
14 #![allow(deprecated)]
15
16 use clone::Clone;
17 use default::Default;
18 use hash;
19 use marker;
20
21 pub use hash::HashState;
22
23 /// A structure which is a factory for instances of `Hasher` which implement the
24 /// default trait.
25 ///
26 /// This struct is 0-sized and does not need construction.
27 pub struct DefaultState<H>(marker::PhantomData<H>);
28
29 impl<H: Default + hash::Hasher> HashState for DefaultState<H> {
30 type Hasher = H;
31 fn hasher(&self) -> H { Default::default() }
32 }
33
34 impl<H> Clone for DefaultState<H> {
35 fn clone(&self) -> DefaultState<H> { DefaultState(marker::PhantomData) }
36 }
37
38 impl<H> Default for DefaultState<H> {
39 fn default() -> DefaultState<H> { DefaultState(marker::PhantomData) }
40 }