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 }