std: Stabilize the std::hash module

This commit aims to prepare the `std::hash` module for alpha by formalizing its
current interface whileholding off on adding `#[stable]` to the new APIs.  The
current usage with the `HashMap` and `HashSet` types is also reconciled by
separating out composable parts of the design. The primary goal of this slight
redesign is to separate the concepts of a hasher's state from a hashing
algorithm itself.

The primary change of this commit is to separate the `Hasher` trait into a
`Hasher` and a `HashState` trait. Conceptually the old `Hasher` trait was
actually just a factory for various states, but hashing had very little control
over how these states were used. Additionally the old `Hasher` trait was
actually fairly unrelated to hashing.

This commit redesigns the existing `Hasher` trait to match what the notion of a
`Hasher` normally implies with the following definition:

    trait Hasher {
        type Output;
        fn reset(&mut self);
        fn finish(&self) -> Output;
    }

This `Hasher` trait emphasizes that hashing algorithms may produce outputs other
than a `u64`, so the output type is made generic. Other than that, however, very
little is assumed about a particular hasher. It is left up to implementors to
provide specific methods or trait implementations to feed data into a hasher.

The corresponding `Hash` trait becomes:

    trait Hash<H: Hasher> {
        fn hash(&self, &mut H);
    }

The old default of `SipState` was removed from this trait as it's not something
that we're willing to stabilize until the end of time, but the type parameter is
always required to implement `Hasher`. Note that the type parameter `H` remains
on the trait to enable multidispatch for specialization of hashing for
particular hashers.

Note that `Writer` is not mentioned in either of `Hash` or `Hasher`, it is
simply used as part `derive` and the implementations for all primitive types.

With these definitions, the old `Hasher` trait is realized as a new `HashState`
trait in the `collections::hash_state` module as an unstable addition for
now. The current definition looks like:

    trait HashState {
        type Hasher: Hasher;
        fn hasher(&self) -> Hasher;
    }

The purpose of this trait is to emphasize that the one piece of functionality
for implementors is that new instances of `Hasher` can be created.  This
conceptually represents the two keys from which more instances of a
`SipHasher` can be created, and a `HashState` is what's stored in a
`HashMap`, not a `Hasher`.

Implementors of custom hash algorithms should implement the `Hasher` trait, and
only hash algorithms intended for use in hash maps need to implement or worry
about the `HashState` trait.

The entire module and `HashState` infrastructure remains `#[unstable]` due to it
being recently redesigned, but some other stability decision made for the
`std::hash` module are:

* The `Writer` trait remains `#[experimental]` as it's intended to be replaced
  with an `io::Writer` (more details soon).
* The top-level `hash` function is `#[unstable]` as it is intended to be generic
  over the hashing algorithm instead of hardwired to `SipHasher`
* The inner `sip` module is now private as its one export, `SipHasher` is
  reexported in the `hash` module.

And finally, a few changes were made to the default parameters on `HashMap`.

* The `RandomSipHasher` default type parameter was renamed to `RandomState`.
  This renaming emphasizes that it is not a hasher, but rather just state to
  generate hashers. It also moves away from the name "sip" as it may not always
  be implemented as `SipHasher`. This type lives in the
  `std::collections::hash_map` module as `#[unstable]`

* The associated `Hasher` type of `RandomState` is creatively called...
  `Hasher`! This concrete structure lives next to `RandomState` as an
  implemenation of the "default hashing algorithm" used for a `HashMap`. Under
  the hood this is currently implemented as `SipHasher`, but it draws an
  explicit interface for now and allows us to modify the implementation over
  time if necessary.

There are many breaking changes outlined above, and as a result this commit is
a:

[breaking-change]

2 files changed, 400 insertions, 533 deletions

diff --git a/src/libcore/hash/mod.rs b/src/libcore/hash/mod.rs
index d8b9cf9594d..a82ea009e13 100644
--- a/src/libcore/hash/mod.rs
+++ b/src/libcore/hash/mod.rs
@@ -16,8 +16,7 @@
 //! # Examples
 //!
 //! ```rust
-//! use std::hash;
-//! use std::hash::Hash;
+//! use std::hash::{hash, Hash, SipHasher};
 //!
 //! #[derive(Hash)]
 //! struct Person {
@@ -29,16 +28,14 @@
 //! 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));
+//! assert!(hash::<_, SipHasher>(&person1) != hash::<_, SipHasher>(&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;
+//! use std::hash::{hash, Hash, Hasher, Writer, SipHasher};
 //!
 //! struct Person {
 //!     id: uint,
@@ -46,8 +43,8 @@
 //!     phone: u64,
 //! }
 //!
-//! impl Hash for Person {
-//!     fn hash(&self, state: &mut SipState) {
+//! impl<H: Hasher + Writer> Hash<H> for Person {
+//!     fn hash(&self, state: &mut H) {
 //!         self.id.hash(state);
 //!         self.phone.hash(state);
 //!     }
@@ -56,186 +53,382 @@
 //! 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));
+//! assert_eq!(hash::<_, SipHasher>(&person1), hash::<_, SipHasher>(&person2));
 //! ```
 
-#![allow(unused_must_use)]
+#![unstable = "module was recently redesigned"]
 
-use prelude::*;
+use default::Default;
 
-use borrow::{Cow, ToOwned};
-use intrinsics::TypeId;
-use mem;
-use num::Int;
+pub use self::sip::SipHasher;
 
-/// Reexport the `sip::hash` function as our default hasher.
-pub use self::sip::hash as hash;
+mod sip;
 
-pub mod sip;
+/// A hashable type.
+///
+/// The `H` type parameter is an abstract hash state that is used by the `Hash`
+/// to compute the hash. Specific implementations of this trait may specialize
+/// for particular instances of `H` in order to be able to optimize the hashing
+/// behavior.
+#[cfg(stage0)]
+pub trait Hash<H> {
+    /// Feeds this value into the state given, updating the hasher as necessary.
+    fn hash(&self, state: &mut H);
+}
 
-/// A hashable type. The `S` type parameter is an abstract hash state that is
-/// used by the `Hash` to compute the hash. It defaults to
-/// `std::hash::sip::SipState`.
-pub trait Hash<S = sip::SipState> {
-    /// Computes the hash of a value.
-    fn hash(&self, state: &mut S);
+/// A hashable type.
+///
+/// The `H` type parameter is an abstract hash state that is used by the `Hash`
+/// to compute the hash. Specific implementations of this trait may specialize
+/// for particular instances of `H` in order to be able to optimize the hashing
+/// behavior.
+#[cfg(not(stage0))]
+pub trait Hash<H: Hasher> {
+    /// Feeds this value into the state given, updating the hasher as necessary.
+    fn hash(&self, state: &mut H);
 }
 
-/// A trait that computes a hash for a value. The main users of this trait are
-/// containers like `HashMap`, which need a generic way hash multiple types.
-pub trait Hasher<S> {
-    /// Compute the hash of a value.
-    fn hash<T: ?Sized + Hash<S>>(&self, value: &T) -> u64;
+/// A trait which represents the ability to hash an arbitrary stream of bytes.
+pub trait Hasher {
+    /// Result type of one run of hashing generated by this hasher.
+    type Output;
+
+    /// Resets this hasher back to its initial state (as if it were just
+    /// created).
+    fn reset(&mut self);
+
+    /// Completes a round of hashing, producing the output hash generated.
+    fn finish(&self) -> Self::Output;
 }
 
+/// A common bound on the `Hasher` parameter to `Hash` implementations in order
+/// to generically hash an aggregate.
+#[experimental = "this trait will likely be replaced by io::Writer"]
 #[allow(missing_docs)]
 pub trait Writer {
     fn write(&mut self, bytes: &[u8]);
 }
 
+/// Hash a value with the default SipHasher algorithm (two initial keys of 0).
+///
+/// The specified value will be hashed with this hasher and then the resulting
+/// hash will be returned.
+pub fn hash<T: Hash<H>, H: Hasher + Default>(value: &T) -> H::Output {
+    let mut h: H = Default::default();
+    value.hash(&mut h);
+    h.finish()
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
-macro_rules! impl_hash {
-    ($ty:ident, $uty:ident) => {
-        impl<S: Writer> Hash<S> for $ty {
-            #[inline]
-            fn hash(&self, state: &mut S) {
-                let a: [u8; ::$ty::BYTES] = unsafe {
-                    mem::transmute((*self as $uty).to_le() as $ty)
-                };
-                state.write(a.as_slice())
+#[cfg(stage0)]
+mod impls {
+    use prelude::*;
+
+    use borrow::{Cow, ToOwned};
+    use intrinsics::TypeId;
+    use mem;
+    use super::{Hash, Writer};
+    use num::Int;
+
+    macro_rules! impl_hash {
+        ($ty:ident, $uty:ident) => {
+            impl<S: Writer> Hash<S> for $ty {
+                #[inline]
+                fn hash(&self, state: &mut S) {
+                    let a: [u8; ::$ty::BYTES] = unsafe {
+                        mem::transmute((*self as $uty).to_le() as $ty)
+                    };
+                    state.write(a.as_slice())
+                }
             }
         }
     }
-}
 
-impl_hash! { u8, u8 }
-impl_hash! { u16, u16 }
-impl_hash! { u32, u32 }
-impl_hash! { u64, u64 }
-impl_hash! { uint, uint }
-impl_hash! { i8, u8 }
-impl_hash! { i16, u16 }
-impl_hash! { i32, u32 }
-impl_hash! { i64, u64 }
-impl_hash! { int, uint }
-
-impl<S: Writer> Hash<S> for bool {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        (*self as u8).hash(state);
+    impl_hash! { u8, u8 }
+    impl_hash! { u16, u16 }
+    impl_hash! { u32, u32 }
+    impl_hash! { u64, u64 }
+    impl_hash! { uint, uint }
+    impl_hash! { i8, u8 }
+    impl_hash! { i16, u16 }
+    impl_hash! { i32, u32 }
+    impl_hash! { i64, u64 }
+    impl_hash! { int, uint }
+
+    impl<S: Writer> Hash<S> for bool {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (*self as u8).hash(state);
+        }
     }
-}
 
-impl<S: Writer> Hash<S> for char {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        (*self as u32).hash(state);
+    impl<S: Writer> Hash<S> for char {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (*self as u32).hash(state);
+        }
     }
-}
 
-impl<S: Writer> Hash<S> for str {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        state.write(self.as_bytes());
-        0xffu8.hash(state)
+    impl<S: Writer> Hash<S> for str {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            state.write(self.as_bytes());
+            0xffu8.hash(state)
+        }
     }
-}
 
-macro_rules! impl_hash_tuple {
-    () => (
-        impl<S: Writer> Hash<S> for () {
-            #[inline]
-            fn hash(&self, state: &mut S) {
-                state.write(&[]);
+    macro_rules! impl_hash_tuple {
+        () => (
+            impl<S> Hash<S> for () {
+                #[inline]
+                fn hash(&self, _state: &mut S) {}
             }
-        }
-    );
-
-    ( $($name:ident)+) => (
-        impl<S: Writer, $($name: Hash<S>),*> Hash<S> for ($($name,)*) {
-            #[inline]
-            #[allow(non_snake_case)]
-            fn hash(&self, state: &mut S) {
-                match *self {
-                    ($(ref $name,)*) => {
-                        $(
-                            $name.hash(state);
-                        )*
+        );
+
+        ( $($name:ident)+) => (
+            impl<S, $($name: Hash<S>),*> Hash<S> for ($($name,)*) {
+                #[inline]
+                #[allow(non_snake_case)]
+                fn hash(&self, state: &mut S) {
+                    match *self {
+                        ($(ref $name,)*) => {
+                            $(
+                                $name.hash(state);
+                            )*
+                        }
                     }
                 }
             }
+        );
+    }
+
+    impl_hash_tuple! {}
+    impl_hash_tuple! { A }
+    impl_hash_tuple! { A B }
+    impl_hash_tuple! { A B C }
+    impl_hash_tuple! { A B C D }
+    impl_hash_tuple! { A B C D E }
+    impl_hash_tuple! { A B C D E F }
+    impl_hash_tuple! { A B C D E F G }
+    impl_hash_tuple! { A B C D E F G H }
+    impl_hash_tuple! { A B C D E F G H I }
+    impl_hash_tuple! { A B C D E F G H I J }
+    impl_hash_tuple! { A B C D E F G H I J K }
+    impl_hash_tuple! { A B C D E F G H I J K L }
+
+    impl<S: Writer, T: Hash<S>> Hash<S> for [T] {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            self.len().hash(state);
+            for elt in self.iter() {
+                elt.hash(state);
+            }
         }
-    );
-}
+    }
+
 
-impl_hash_tuple! {}
-impl_hash_tuple! { A }
-impl_hash_tuple! { A B }
-impl_hash_tuple! { A B C }
-impl_hash_tuple! { A B C D }
-impl_hash_tuple! { A B C D E }
-impl_hash_tuple! { A B C D E F }
-impl_hash_tuple! { A B C D E F G }
-impl_hash_tuple! { A B C D E F G H }
-impl_hash_tuple! { A B C D E F G H I }
-impl_hash_tuple! { A B C D E F G H I J }
-impl_hash_tuple! { A B C D E F G H I J K }
-impl_hash_tuple! { A B C D E F G H I J K L }
-
-impl<S: Writer, T: Hash<S>> Hash<S> for [T] {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        self.len().hash(state);
-        for elt in self.iter() {
-            elt.hash(state);
+    impl<'a, S, T: ?Sized + Hash<S>> Hash<S> for &'a T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (**self).hash(state);
         }
     }
-}
 
+    impl<'a, S, T: ?Sized + Hash<S>> Hash<S> for &'a mut T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (**self).hash(state);
+        }
+    }
 
-impl<'a, S: Writer, T: ?Sized + Hash<S>> Hash<S> for &'a T {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        (**self).hash(state);
+    impl<S: Writer, T> Hash<S> for *const T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            // NB: raw-pointer Hash does _not_ dereference
+            // to the target; it just gives you the pointer-bytes.
+            (*self as uint).hash(state);
+        }
     }
-}
 
-impl<'a, S: Writer, T: ?Sized + Hash<S>> Hash<S> for &'a mut T {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        (**self).hash(state);
+    impl<S: Writer, T> Hash<S> for *mut T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            // NB: raw-pointer Hash does _not_ dereference
+            // to the target; it just gives you the pointer-bytes.
+            (*self as uint).hash(state);
+        }
     }
-}
 
-impl<S: Writer, T> Hash<S> for *const T {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        // NB: raw-pointer Hash does _not_ dereference
-        // to the target; it just gives you the pointer-bytes.
-        (*self as uint).hash(state);
+    impl<S: Writer> Hash<S> for TypeId {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            self.hash().hash(state)
+        }
     }
-}
 
-impl<S: Writer, T> Hash<S> for *mut T {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        // NB: raw-pointer Hash does _not_ dereference
-        // to the target; it just gives you the pointer-bytes.
-        (*self as uint).hash(state);
+    impl<'a, T, B: ?Sized, S> Hash<S> for Cow<'a, T, B>
+        where B: Hash<S> + ToOwned<T>
+    {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            Hash::hash(&**self, state)
+        }
     }
 }
 
-impl<S: Writer> Hash<S> for TypeId {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        self.hash().hash(state)
+#[cfg(not(stage0))]
+mod impls {
+    use prelude::*;
+
+    use borrow::{Cow, ToOwned};
+    use intrinsics::TypeId;
+    use mem;
+    use super::{Hash, Writer, Hasher};
+    use num::Int;
+
+    macro_rules! impl_hash {
+        ($ty:ident, $uty:ident) => {
+            impl<S: Writer + Hasher> Hash<S> for $ty {
+                #[inline]
+                fn hash(&self, state: &mut S) {
+                    let a: [u8; ::$ty::BYTES] = unsafe {
+                        mem::transmute((*self as $uty).to_le() as $ty)
+                    };
+                    state.write(a.as_slice())
+                }
+            }
+        }
+    }
+
+    impl_hash! { u8, u8 }
+    impl_hash! { u16, u16 }
+    impl_hash! { u32, u32 }
+    impl_hash! { u64, u64 }
+    impl_hash! { uint, uint }
+    impl_hash! { i8, u8 }
+    impl_hash! { i16, u16 }
+    impl_hash! { i32, u32 }
+    impl_hash! { i64, u64 }
+    impl_hash! { int, uint }
+
+    impl<S: Writer + Hasher> Hash<S> for bool {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (*self as u8).hash(state);
+        }
+    }
+
+    impl<S: Writer + Hasher> Hash<S> for char {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (*self as u32).hash(state);
+        }
+    }
+
+    impl<S: Writer + Hasher> Hash<S> for str {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            state.write(self.as_bytes());
+            0xffu8.hash(state)
+        }
+    }
+
+    macro_rules! impl_hash_tuple {
+        () => (
+            impl<S: Hasher> Hash<S> for () {
+                #[inline]
+                fn hash(&self, _state: &mut S) {}
+            }
+        );
+
+        ( $($name:ident)+) => (
+            impl<S: Hasher, $($name: Hash<S>),*> Hash<S> for ($($name,)*) {
+                #[inline]
+                #[allow(non_snake_case)]
+                fn hash(&self, state: &mut S) {
+                    match *self {
+                        ($(ref $name,)*) => {
+                            $(
+                                $name.hash(state);
+                            )*
+                        }
+                    }
+                }
+            }
+        );
+    }
+
+    impl_hash_tuple! {}
+    impl_hash_tuple! { A }
+    impl_hash_tuple! { A B }
+    impl_hash_tuple! { A B C }
+    impl_hash_tuple! { A B C D }
+    impl_hash_tuple! { A B C D E }
+    impl_hash_tuple! { A B C D E F }
+    impl_hash_tuple! { A B C D E F G }
+    impl_hash_tuple! { A B C D E F G H }
+    impl_hash_tuple! { A B C D E F G H I }
+    impl_hash_tuple! { A B C D E F G H I J }
+    impl_hash_tuple! { A B C D E F G H I J K }
+    impl_hash_tuple! { A B C D E F G H I J K L }
+
+    impl<S: Writer + Hasher, T: Hash<S>> Hash<S> for [T] {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            self.len().hash(state);
+            for elt in self.iter() {
+                elt.hash(state);
+            }
+        }
+    }
+
+
+    impl<'a, S: Hasher, T: ?Sized + Hash<S>> Hash<S> for &'a T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (**self).hash(state);
+        }
+    }
+
+    impl<'a, S: Hasher, T: ?Sized + Hash<S>> Hash<S> for &'a mut T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            (**self).hash(state);
+        }
     }
-}
 
-impl<'a, T, B: ?Sized, S> Hash<S> for Cow<'a, T, B> where B: Hash<S> + ToOwned<T> {
-    #[inline]
-    fn hash(&self, state: &mut S) {
-        Hash::hash(&**self, state)
+    impl<S: Writer + Hasher, T> Hash<S> for *const T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            // NB: raw-pointer Hash does _not_ dereference
+            // to the target; it just gives you the pointer-bytes.
+            (*self as uint).hash(state);
+        }
+    }
+
+    impl<S: Writer + Hasher, T> Hash<S> for *mut T {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            // NB: raw-pointer Hash does _not_ dereference
+            // to the target; it just gives you the pointer-bytes.
+            (*self as uint).hash(state);
+        }
+    }
+
+    impl<S: Writer + Hasher> Hash<S> for TypeId {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            self.hash().hash(state)
+        }
+    }
+
+    impl<'a, T, B: ?Sized, S: Hasher> Hash<S> for Cow<'a, T, B>
+        where B: Hash<S> + ToOwned<T>
+    {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            Hash::hash(&**self, state)
+        }
     }
 }
diff --git a/src/libcore/hash/sip.rs b/src/libcore/hash/sip.rs
index c4d45e9c2c8..c20fb8457d2 100644
--- a/src/libcore/hash/sip.rs
+++ b/src/libcore/hash/sip.rs
@@ -11,27 +11,27 @@
 // ignore-lexer-test FIXME #15883
 
 //! An implementation of SipHash 2-4.
-//!
-//! See: http://131002.net/siphash/
-//!
-//! Consider this as a main "general-purpose" hash for all hashtables: it
-//! runs at good speed (competitive with spooky and city) and permits
-//! strong _keyed_ hashing. Key your hashtables from a strong RNG,
-//! such as `rand::Rng`.
-//!
-//! Although the SipHash algorithm is considered to be cryptographically
-//! strong, this implementation has not been reviewed for such purposes.
-//! As such, all cryptographic uses of this implementation are strongly
-//! discouraged.
 
 use prelude::*;
 use default::Default;
 
-use super::{Hash, Hasher, Writer};
-
-/// `SipState` computes a SipHash 2-4 hash over a stream of bytes.
-#[derive(Copy)]
-pub struct SipState {
+use super::{Hasher, Writer};
+
+/// An implementation of SipHash 2-4.
+///
+/// See: http://131002.net/siphash/
+///
+/// Consider this as a main "general-purpose" hash for all hashtables: it
+/// runs at good speed (competitive with spooky and city) and permits
+/// strong _keyed_ hashing. Key your hashtables from a strong RNG,
+/// such as `rand::Rng`.
+///
+/// Although the SipHash algorithm is considered to be cryptographically
+/// strong, this implementation has not been reviewed for such purposes.
+/// As such, all cryptographic uses of this implementation are strongly
+/// discouraged.
+#[allow(missing_copy_implementations)]
+pub struct SipHasher {
     k0: u64,
     k1: u64,
     length: uint, // how many bytes we've processed
@@ -86,17 +86,17 @@ macro_rules! compress {
     })
 }
 
-impl SipState {
-    /// Creates a `SipState` that is keyed off the provided keys.
+impl SipHasher {
+    /// Creates a new `SipHasher` with the two initial keys set to 0.
     #[inline]
-    pub fn new() -> SipState {
-        SipState::new_with_keys(0, 0)
+    pub fn new() -> SipHasher {
+        SipHasher::new_with_keys(0, 0)
     }
 
-    /// Creates a `SipState` that is keyed off the provided keys.
+    /// Creates a `SipHasher` that is keyed off the provided keys.
     #[inline]
-    pub fn new_with_keys(key0: u64, key1: u64) -> SipState {
-        let mut state = SipState {
+    pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
+        let mut state = SipHasher {
             k0: key0,
             k1: key1,
             length: 0,
@@ -111,43 +111,12 @@ impl SipState {
         state
     }
 
-    /// Resets the state to its initial state.
-    #[inline]
-    pub fn reset(&mut self) {
-        self.length = 0;
-        self.v0 = self.k0 ^ 0x736f6d6570736575;
-        self.v1 = self.k1 ^ 0x646f72616e646f6d;
-        self.v2 = self.k0 ^ 0x6c7967656e657261;
-        self.v3 = self.k1 ^ 0x7465646279746573;
-        self.ntail = 0;
-    }
-
     /// Returns the computed hash.
-    #[inline]
-    pub fn result(&self) -> u64 {
-        let mut v0 = self.v0;
-        let mut v1 = self.v1;
-        let mut v2 = self.v2;
-        let mut v3 = self.v3;
-
-        let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;
-
-        v3 ^= b;
-        compress!(v0, v1, v2, v3);
-        compress!(v0, v1, v2, v3);
-        v0 ^= b;
-
-        v2 ^= 0xff;
-        compress!(v0, v1, v2, v3);
-        compress!(v0, v1, v2, v3);
-        compress!(v0, v1, v2, v3);
-        compress!(v0, v1, v2, v3);
-
-        v0 ^ v1 ^ v2 ^ v3
-    }
+    #[deprecated = "renamed to finish"]
+    pub fn result(&self) -> u64 { self.finish() }
 }
 
-impl Writer for SipState {
+impl Writer for SipHasher {
     #[inline]
     fn write(&mut self, msg: &[u8]) {
         let length = msg.len();
@@ -195,355 +164,60 @@ impl Writer for SipState {
     }
 }
 
-#[stable]
-impl Clone for SipState {
-    #[inline]
-    fn clone(&self) -> SipState {
-        *self
-    }
-}
+impl Hasher for SipHasher {
+    type Output = u64;
 
-#[stable]
-impl Default for SipState {
-    #[inline]
-    #[stable]
-    fn default() -> SipState {
-        SipState::new()
+    fn reset(&mut self) {
+        self.length = 0;
+        self.v0 = self.k0 ^ 0x736f6d6570736575;
+        self.v1 = self.k1 ^ 0x646f72616e646f6d;
+        self.v2 = self.k0 ^ 0x6c7967656e657261;
+        self.v3 = self.k1 ^ 0x7465646279746573;
+        self.ntail = 0;
     }
-}
 
-/// `SipHasher` computes the SipHash algorithm from a stream of bytes.
-#[derive(Clone)]
-#[allow(missing_copy_implementations)]
-pub struct SipHasher {
-    k0: u64,
-    k1: u64,
-}
+    fn finish(&self) -> u64 {
+        let mut v0 = self.v0;
+        let mut v1 = self.v1;
+        let mut v2 = self.v2;
+        let mut v3 = self.v3;
 
-impl SipHasher {
-    /// Creates a `Sip`.
-    #[inline]
-    pub fn new() -> SipHasher {
-        SipHasher::new_with_keys(0, 0)
-    }
+        let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;
 
-    /// Creates a `Sip` that is keyed off the provided keys.
-    #[inline]
-    pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
-        SipHasher {
-            k0: key0,
-            k1: key1,
-        }
+        v3 ^= b;
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        v0 ^= b;
+
+        v2 ^= 0xff;
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+
+        v0 ^ v1 ^ v2 ^ v3
     }
 }
 
-impl Hasher<SipState> for SipHasher {
+impl Clone for SipHasher {
     #[inline]
-    fn hash<T: ?Sized + Hash<SipState>>(&self, value: &T) -> u64 {
-        let mut state = SipState::new_with_keys(self.k0, self.k1);
-        value.hash(&mut state);
-        state.result()
+    fn clone(&self) -> SipHasher {
+        SipHasher {
+            k0: self.k0,
+            k1: self.k1,
+            length: self.length,
+            v0: self.v0,
+            v1: self.v1,
+            v2: self.v2,
+            v3: self.v3,
+            tail: self.tail,
+            ntail: self.ntail,
+        }
     }
 }
 
 impl Default for SipHasher {
-    #[inline]
     fn default() -> SipHasher {
         SipHasher::new()
     }
 }
-
-/// Hashes a value using the SipHash algorithm.
-#[inline]
-pub fn hash<T: ?Sized + Hash<SipState>>(value: &T) -> u64 {
-    let mut state = SipState::new();
-    value.hash(&mut state);
-    state.result()
-}
-
-/// Hashes a value with the SipHash algorithm with the provided keys.
-#[inline]
-pub fn hash_with_keys<T: ?Sized + Hash<SipState>>(k0: u64, k1: u64, value: &T) -> u64 {
-    let mut state = SipState::new_with_keys(k0, k1);
-    value.hash(&mut state);
-    state.result()
-}
-
-#[cfg(test)]
-mod tests {
-    use test::Bencher;
-    use prelude::*;
-    use std::fmt;
-
-    use super::super::{Hash, Writer};
-    use super::{SipState, hash, hash_with_keys};
-
-    // Hash just the bytes of the slice, without length prefix
-    struct Bytes<'a>(&'a [u8]);
-
-    impl<'a, S: Writer> Hash<S> for Bytes<'a> {
-        #[allow(unused_must_use)]
-        fn hash(&self, state: &mut S) {
-            let Bytes(v) = *self;
-            state.write(v);
-        }
-    }
-
-    #[test]
-    #[allow(unused_must_use)]
-    fn test_siphash() {
-        let vecs : [[u8; 8]; 64] = [
-            [ 0x31, 0x0e, 0x0e, 0xdd, 0x47, 0xdb, 0x6f, 0x72, ],
-            [ 0xfd, 0x67, 0xdc, 0x93, 0xc5, 0x39, 0xf8, 0x74, ],
-            [ 0x5a, 0x4f, 0xa9, 0xd9, 0x09, 0x80, 0x6c, 0x0d, ],
-            [ 0x2d, 0x7e, 0xfb, 0xd7, 0x96, 0x66, 0x67, 0x85, ],
-            [ 0xb7, 0x87, 0x71, 0x27, 0xe0, 0x94, 0x27, 0xcf, ],
-            [ 0x8d, 0xa6, 0x99, 0xcd, 0x64, 0x55, 0x76, 0x18, ],
-            [ 0xce, 0xe3, 0xfe, 0x58, 0x6e, 0x46, 0xc9, 0xcb, ],
-            [ 0x37, 0xd1, 0x01, 0x8b, 0xf5, 0x00, 0x02, 0xab, ],
-            [ 0x62, 0x24, 0x93, 0x9a, 0x79, 0xf5, 0xf5, 0x93, ],
-            [ 0xb0, 0xe4, 0xa9, 0x0b, 0xdf, 0x82, 0x00, 0x9e, ],
-            [ 0xf3, 0xb9, 0xdd, 0x94, 0xc5, 0xbb, 0x5d, 0x7a, ],
-            [ 0xa7, 0xad, 0x6b, 0x22, 0x46, 0x2f, 0xb3, 0xf4, ],
-            [ 0xfb, 0xe5, 0x0e, 0x86, 0xbc, 0x8f, 0x1e, 0x75, ],
-            [ 0x90, 0x3d, 0x84, 0xc0, 0x27, 0x56, 0xea, 0x14, ],
-            [ 0xee, 0xf2, 0x7a, 0x8e, 0x90, 0xca, 0x23, 0xf7, ],
-            [ 0xe5, 0x45, 0xbe, 0x49, 0x61, 0xca, 0x29, 0xa1, ],
-            [ 0xdb, 0x9b, 0xc2, 0x57, 0x7f, 0xcc, 0x2a, 0x3f, ],
-            [ 0x94, 0x47, 0xbe, 0x2c, 0xf5, 0xe9, 0x9a, 0x69, ],
-            [ 0x9c, 0xd3, 0x8d, 0x96, 0xf0, 0xb3, 0xc1, 0x4b, ],
-            [ 0xbd, 0x61, 0x79, 0xa7, 0x1d, 0xc9, 0x6d, 0xbb, ],
-            [ 0x98, 0xee, 0xa2, 0x1a, 0xf2, 0x5c, 0xd6, 0xbe, ],
-            [ 0xc7, 0x67, 0x3b, 0x2e, 0xb0, 0xcb, 0xf2, 0xd0, ],
-            [ 0x88, 0x3e, 0xa3, 0xe3, 0x95, 0x67, 0x53, 0x93, ],
-            [ 0xc8, 0xce, 0x5c, 0xcd, 0x8c, 0x03, 0x0c, 0xa8, ],
-            [ 0x94, 0xaf, 0x49, 0xf6, 0xc6, 0x50, 0xad, 0xb8, ],
-            [ 0xea, 0xb8, 0x85, 0x8a, 0xde, 0x92, 0xe1, 0xbc, ],
-            [ 0xf3, 0x15, 0xbb, 0x5b, 0xb8, 0x35, 0xd8, 0x17, ],
-            [ 0xad, 0xcf, 0x6b, 0x07, 0x63, 0x61, 0x2e, 0x2f, ],
-            [ 0xa5, 0xc9, 0x1d, 0xa7, 0xac, 0xaa, 0x4d, 0xde, ],
-            [ 0x71, 0x65, 0x95, 0x87, 0x66, 0x50, 0xa2, 0xa6, ],
-            [ 0x28, 0xef, 0x49, 0x5c, 0x53, 0xa3, 0x87, 0xad, ],
-            [ 0x42, 0xc3, 0x41, 0xd8, 0xfa, 0x92, 0xd8, 0x32, ],
-            [ 0xce, 0x7c, 0xf2, 0x72, 0x2f, 0x51, 0x27, 0x71, ],
-            [ 0xe3, 0x78, 0x59, 0xf9, 0x46, 0x23, 0xf3, 0xa7, ],
-            [ 0x38, 0x12, 0x05, 0xbb, 0x1a, 0xb0, 0xe0, 0x12, ],
-            [ 0xae, 0x97, 0xa1, 0x0f, 0xd4, 0x34, 0xe0, 0x15, ],
-            [ 0xb4, 0xa3, 0x15, 0x08, 0xbe, 0xff, 0x4d, 0x31, ],
-            [ 0x81, 0x39, 0x62, 0x29, 0xf0, 0x90, 0x79, 0x02, ],
-            [ 0x4d, 0x0c, 0xf4, 0x9e, 0xe5, 0xd4, 0xdc, 0xca, ],
-            [ 0x5c, 0x73, 0x33, 0x6a, 0x76, 0xd8, 0xbf, 0x9a, ],
-            [ 0xd0, 0xa7, 0x04, 0x53, 0x6b, 0xa9, 0x3e, 0x0e, ],
-            [ 0x92, 0x59, 0x58, 0xfc, 0xd6, 0x42, 0x0c, 0xad, ],
-            [ 0xa9, 0x15, 0xc2, 0x9b, 0xc8, 0x06, 0x73, 0x18, ],
-            [ 0x95, 0x2b, 0x79, 0xf3, 0xbc, 0x0a, 0xa6, 0xd4, ],
-            [ 0xf2, 0x1d, 0xf2, 0xe4, 0x1d, 0x45, 0x35, 0xf9, ],
-            [ 0x87, 0x57, 0x75, 0x19, 0x04, 0x8f, 0x53, 0xa9, ],
-            [ 0x10, 0xa5, 0x6c, 0xf5, 0xdf, 0xcd, 0x9a, 0xdb, ],
-            [ 0xeb, 0x75, 0x09, 0x5c, 0xcd, 0x98, 0x6c, 0xd0, ],
-            [ 0x51, 0xa9, 0xcb, 0x9e, 0xcb, 0xa3, 0x12, 0xe6, ],
-            [ 0x96, 0xaf, 0xad, 0xfc, 0x2c, 0xe6, 0x66, 0xc7, ],
-            [ 0x72, 0xfe, 0x52, 0x97, 0x5a, 0x43, 0x64, 0xee, ],
-            [ 0x5a, 0x16, 0x45, 0xb2, 0x76, 0xd5, 0x92, 0xa1, ],
-            [ 0xb2, 0x74, 0xcb, 0x8e, 0xbf, 0x87, 0x87, 0x0a, ],
-            [ 0x6f, 0x9b, 0xb4, 0x20, 0x3d, 0xe7, 0xb3, 0x81, ],
-            [ 0xea, 0xec, 0xb2, 0xa3, 0x0b, 0x22, 0xa8, 0x7f, ],
-            [ 0x99, 0x24, 0xa4, 0x3c, 0xc1, 0x31, 0x57, 0x24, ],
-            [ 0xbd, 0x83, 0x8d, 0x3a, 0xaf, 0xbf, 0x8d, 0xb7, ],
-            [ 0x0b, 0x1a, 0x2a, 0x32, 0x65, 0xd5, 0x1a, 0xea, ],
-            [ 0x13, 0x50, 0x79, 0xa3, 0x23, 0x1c, 0xe6, 0x60, ],
-            [ 0x93, 0x2b, 0x28, 0x46, 0xe4, 0xd7, 0x06, 0x66, ],
-            [ 0xe1, 0x91, 0x5f, 0x5c, 0xb1, 0xec, 0xa4, 0x6c, ],
-            [ 0xf3, 0x25, 0x96, 0x5c, 0xa1, 0x6d, 0x62, 0x9f, ],
-            [ 0x57, 0x5f, 0xf2, 0x8e, 0x60, 0x38, 0x1b, 0xe5, ],
-            [ 0x72, 0x45, 0x06, 0xeb, 0x4c, 0x32, 0x8a, 0x95, ]
-        ];
-
-        let k0 = 0x_07_06_05_04_03_02_01_00_u64;
-        let k1 = 0x_0f_0e_0d_0c_0b_0a_09_08_u64;
-        let mut buf = Vec::new();
-        let mut t = 0;
-        let mut state_inc = SipState::new_with_keys(k0, k1);
-        let mut state_full = SipState::new_with_keys(k0, k1);
-
-        fn to_hex_str(r: &[u8; 8]) -> String {
-            let mut s = String::new();
-            for b in r.iter() {
-                s.push_str(format!("{}", fmt::radix(*b, 16)).as_slice());
-            }
-            s
-        }
-
-        fn result_bytes(h: u64) -> Vec<u8> {
-            vec![(h >> 0) as u8,
-              (h >> 8) as u8,
-              (h >> 16) as u8,
-              (h >> 24) as u8,
-              (h >> 32) as u8,
-              (h >> 40) as u8,
-              (h >> 48) as u8,
-              (h >> 56) as u8,
-            ]
-        }
-
-        fn result_str(h: u64) -> String {
-            let r = result_bytes(h);
-            let mut s = String::new();
-            for b in r.iter() {
-                s.push_str(format!("{}", fmt::radix(*b, 16)).as_slice());
-            }
-            s
-        }
-
-        while t < 64 {
-            debug!("siphash test {}: {}", t, buf);
-            let vec = u8to64_le!(vecs[t], 0);
-            let out = hash_with_keys(k0, k1, &Bytes(buf.as_slice()));
-            debug!("got {}, expected {}", out, vec);
-            assert_eq!(vec, out);
-
-            state_full.reset();
-            state_full.write(buf.as_slice());
-            let f = result_str(state_full.result());
-            let i = result_str(state_inc.result());
-            let v = to_hex_str(&vecs[t]);
-            debug!("{}: ({}) => inc={} full={}", t, v, i, f);
-
-            assert_eq!(f, i);
-            assert_eq!(f, v);
-
-            buf.push(t as u8);
-            state_inc.write(&[t as u8]);
-
-            t += 1;
-        }
-    }
-
-    #[test] #[cfg(target_arch = "aarch64")]
-    fn test_hash_uint() {
-        let val = 0xdeadbeef_deadbeef_u64;
-        assert_eq!(hash(&(val as u64)), hash(&(val as uint)));
-        assert!(hash(&(val as u32)) != hash(&(val as uint)));
-    }
-    #[test] #[cfg(target_arch = "arm")]
-    fn test_hash_uint() {
-        let val = 0xdeadbeef_deadbeef_u64;
-        assert!(hash(&(val as u64)) != hash(&(val as uint)));
-        assert_eq!(hash(&(val as u32)), hash(&(val as uint)));
-    }
-    #[test] #[cfg(target_arch = "x86_64")]
-    fn test_hash_uint() {
-        let val = 0xdeadbeef_deadbeef_u64;
-        assert_eq!(hash(&(val as u64)), hash(&(val as uint)));
-        assert!(hash(&(val as u32)) != hash(&(val as uint)));
-    }
-    #[test] #[cfg(target_arch = "x86")]
-    fn test_hash_uint() {
-        let val = 0xdeadbeef_deadbeef_u64;
-        assert!(hash(&(val as u64)) != hash(&(val as uint)));
-        assert_eq!(hash(&(val as u32)), hash(&(val as uint)));
-    }
-
-    #[test]
-    fn test_hash_idempotent() {
-        let val64 = 0xdeadbeef_deadbeef_u64;
-        assert_eq!(hash(&val64), hash(&val64));
-        let val32 = 0xdeadbeef_u32;
-        assert_eq!(hash(&val32), hash(&val32));
-    }
-
-    #[test]
-    fn test_hash_no_bytes_dropped_64() {
-        let val = 0xdeadbeef_deadbeef_u64;
-
-        assert!(hash(&val) != hash(&zero_byte(val, 0)));
-        assert!(hash(&val) != hash(&zero_byte(val, 1)));
-        assert!(hash(&val) != hash(&zero_byte(val, 2)));
-        assert!(hash(&val) != hash(&zero_byte(val, 3)));
-        assert!(hash(&val) != hash(&zero_byte(val, 4)));
-        assert!(hash(&val) != hash(&zero_byte(val, 5)));
-        assert!(hash(&val) != hash(&zero_byte(val, 6)));
-        assert!(hash(&val) != hash(&zero_byte(val, 7)));
-
-        fn zero_byte(val: u64, byte: uint) -> u64 {
-            assert!(byte < 8);
-            val & !(0xff << (byte * 8))
-        }
-    }
-
-    #[test]
-    fn test_hash_no_bytes_dropped_32() {
-        let val = 0xdeadbeef_u32;
-
-        assert!(hash(&val) != hash(&zero_byte(val, 0)));
-        assert!(hash(&val) != hash(&zero_byte(val, 1)));
-        assert!(hash(&val) != hash(&zero_byte(val, 2)));
-        assert!(hash(&val) != hash(&zero_byte(val, 3)));
-
-        fn zero_byte(val: u32, byte: uint) -> u32 {
-            assert!(byte < 4);
-            val & !(0xff << (byte * 8))
-        }
-    }
-
-    #[test]
-    fn test_hash_no_concat_alias() {
-        let s = ("aa", "bb");
-        let t = ("aabb", "");
-        let u = ("a", "abb");
-
-        assert!(s != t && t != u);
-        assert!(hash(&s) != hash(&t) && hash(&s) != hash(&u));
-
-        let v: (&[u8], &[u8], &[u8]) = (&[1u8], &[0u8, 0], &[0u8]);
-        let w: (&[u8], &[u8], &[u8]) = (&[1u8, 0, 0, 0], &[], &[]);
-
-        assert!(v != w);
-        assert!(hash(&v) != hash(&w));
-    }
-
-    #[bench]
-    fn bench_str_under_8_bytes(b: &mut Bencher) {
-        let s = "foo";
-        b.iter(|| {
-            assert_eq!(hash(&s), 16262950014981195938);
-        })
-    }
-
-    #[bench]
-    fn bench_str_of_8_bytes(b: &mut Bencher) {
-        let s = "foobar78";
-        b.iter(|| {
-            assert_eq!(hash(&s), 4898293253460910787);
-        })
-    }
-
-    #[bench]
-    fn bench_str_over_8_bytes(b: &mut Bencher) {
-        let s = "foobarbaz0";
-        b.iter(|| {
-            assert_eq!(hash(&s), 10581415515220175264);
-        })
-    }
-
-    #[bench]
-    fn bench_long_str(b: &mut Bencher) {
-        let s = "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor \
-incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud \
-exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute \
-irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla \
-pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui \
-officia deserunt mollit anim id est laborum.";
-        b.iter(|| {
-            assert_eq!(hash(&s), 17717065544121360093);
-        })
-    }
-
-    #[bench]
-    fn bench_u64(b: &mut Bencher) {
-        let u = 16262950014981195938u64;
-        b.iter(|| {
-            assert_eq!(hash(&u), 5254097107239593357);
-        })
-    }
-}