std: rewrite Hash to make it more generic

This patch merges IterBytes and Hash traits, which clears up the
confusion of using `#[deriving(IterBytes)]` to support hashing.
Instead, it now is much easier to use the new `#[deriving(Hash)]`
for making a type hashable with a stream hash.

Furthermore, it supports custom non-stream-based hashers, such as
if a value's hash was cached in a database.

This does not yet replace the old IterBytes-hash with this new
version.

2 files changed, 888 insertions, 0 deletions

diff --git a/src/libstd/hash/mod.rs b/src/libstd/hash/mod.rs
new file mode 100644
index 00000000000..ac079cb3fb3
--- /dev/null
+++ b/src/libstd/hash/mod.rs
@@ -0,0 +1,369 @@
+// Copyright 2012-2014 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: ~str,
+ *     phone: uint,
+ * }
+ *
+ * let person1 = Person { id: 5, name: ~"Janet", phone: 555_666_7777 };
+ * let person2 = Person { id: 5, name: ~"Bob", 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: ~str,
+ *     phone: uint,
+ * }
+ *
+ * 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", phone: 555_666_7777 };
+ * let person2 = Person { id: 5, name: ~"Bob", phone: 555_666_7777 };
+ *
+ * assert!(hash::hash(&person1) == hash::hash(&person2));
+ * ```
+ */
+
+#[allow(unused_must_use)];
+
+use container::Container;
+use io::Writer;
+use iter::Iterator;
+use option::{Option, Some, None};
+use rc::Rc;
+use str::{Str, StrSlice};
+use vec::{Vector, ImmutableVector};
+
+/// Reexport the `sip::hash` function as our default hasher.
+pub use hash = self::sip::hash;
+
+pub mod sip;
+
+/// A trait that represents 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> {
+    /// Compute a hash of the value.
+    fn hash(&self, state: &mut S);
+}
+
+/// 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 a hash of the value.
+    fn hash<T: Hash<S>>(&self, value: &T) -> u64;
+}
+
+//////////////////////////////////////////////////////////////////////////////
+
+macro_rules! impl_hash(
+    ( $( $ty:ty => $method:ident;)* ) => (
+        $(
+            impl<S: Writer> Hash<S> for $ty {
+                #[inline]
+                fn hash(&self, state: &mut S) {
+                    state.$method(*self);
+                }
+            }
+        )*
+    )
+)
+
+impl_hash!(
+    u8 => write_u8;
+    u16 => write_le_u16;
+    u32 => write_le_u32;
+    u64 => write_le_u64;
+    uint => write_le_uint;
+    i8 => write_i8;
+    i16 => write_le_i16;
+    i32 => write_le_i32;
+    i64 => write_le_i64;
+    int => write_le_int;
+)
+
+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<'a, S: Writer> Hash<S> for &'a str {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        state.write(self.as_bytes());
+        state.write_u8(0xFF);
+    }
+}
+
+impl<S: Writer> Hash<S> for ~str {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        self.as_slice().hash(state);
+    }
+}
+
+macro_rules! impl_hash_tuple(
+    () => (
+        impl<S: Writer> Hash<S> for () {
+            #[inline]
+            fn hash(&self, state: &mut S) {
+                state.write([]);
+            }
+        }
+    );
+
+    ($A:ident $($B:ident)*) => (
+        impl<
+            S: Writer,
+            $A: Hash<S> $(, $B: Hash<S>)*
+        > Hash<S> for ($A, $($B),*) {
+            #[inline]
+            fn hash(&self, state: &mut S) {
+                match *self {
+                    (ref $A, $(ref $B),*) => {
+                        $A.hash(state);
+                        $(
+                            $B.hash(state);
+                        )*
+                    }
+                }
+            }
+        }
+
+        impl_hash_tuple!($($B)*)
+    );
+)
+
+impl_hash_tuple!(A0 A1 A2 A3 A4 A5 A6 A7)
+
+impl<'a, S: Writer, T: Hash<S>> Hash<S> for &'a [T] {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        self.len().hash(state);
+        for elt in self.iter() {
+            elt.hash(state);
+        }
+    }
+}
+
+
+impl<'a, S: Writer, T: Hash<S>> Hash<S> for &'a mut [T] {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        self.as_slice().hash(state);
+    }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for ~[T] {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        self.as_slice().hash(state);
+    }
+}
+
+impl<'a, S: Writer, T: Hash<S>> Hash<S> for &'a T {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        (**self).hash(state);
+    }
+}
+
+impl<'a, S: Writer, T: Hash<S>> Hash<S> for &'a mut T {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        (**self).hash(state);
+    }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for ~T {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        (**self).hash(state);
+    }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for @T {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        (**self).hash(state);
+    }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for Rc<T> {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        self.borrow().hash(state);
+    }
+}
+
+impl<S: Writer, T: Hash<S>> Hash<S> for Option<T> {
+    #[inline]
+    fn hash(&self, state: &mut S) {
+        match *self {
+            Some(ref x) => {
+                0u8.hash(state);
+                x.hash(state);
+            }
+            None => {
+                1u8.hash(state);
+            }
+        }
+    }
+}
+
+impl<S: Writer, T> Hash<S> for *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 *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);
+    }
+}
+
+//////////////////////////////////////////////////////////////////////////////
+
+#[cfg(test)]
+mod tests {
+    use cast;
+    use io::{IoResult, Writer};
+    use iter::{Iterator};
+    use option::{Some, None};
+    use result::Ok;
+    use vec::ImmutableVector;
+
+    use super::{Hash, Hasher};
+
+    struct MyWriterHasher;
+
+    impl Hasher<MyWriter> for MyWriterHasher {
+        fn hash<T: Hash<MyWriter>>(&self, value: &T) -> u64 {
+            let mut state = MyWriter { hash: 0 };
+            value.hash(&mut state);
+            state.hash
+        }
+    }
+
+    struct MyWriter {
+        hash: u64,
+    }
+
+    impl Writer for MyWriter {
+        // Most things we'll just add up the bytes.
+        fn write(&mut self, buf: &[u8]) -> IoResult<()> {
+            for byte in buf.iter() {
+                self.hash += *byte as u64;
+            }
+            Ok(())
+        }
+    }
+
+    #[test]
+    fn test_writer_hasher() {
+        let hasher = MyWriterHasher;
+
+        assert_eq!(hasher.hash(&()), 0);
+
+        assert_eq!(hasher.hash(&5u8), 5);
+        assert_eq!(hasher.hash(&5u16), 5);
+        assert_eq!(hasher.hash(&5u32), 5);
+        assert_eq!(hasher.hash(&5u64), 5);
+        assert_eq!(hasher.hash(&5u), 5);
+
+        assert_eq!(hasher.hash(&5i8), 5);
+        assert_eq!(hasher.hash(&5i16), 5);
+        assert_eq!(hasher.hash(&5i32), 5);
+        assert_eq!(hasher.hash(&5i64), 5);
+        assert_eq!(hasher.hash(&5i), 5);
+
+        assert_eq!(hasher.hash(&false), 0);
+        assert_eq!(hasher.hash(&true), 1);
+
+        assert_eq!(hasher.hash(&'a'), 97);
+
+        assert_eq!(hasher.hash(& &"a"), 97 + 0xFF);
+        assert_eq!(hasher.hash(& &[1u8, 2u8, 3u8]), 9);
+
+        unsafe {
+            let ptr: *int = cast::transmute(5);
+            assert_eq!(hasher.hash(&ptr), 5);
+        }
+
+        unsafe {
+            let ptr: *mut int = cast::transmute(5);
+            assert_eq!(hasher.hash(&ptr), 5);
+        }
+    }
+
+    struct Custom {
+        hash: u64
+    }
+
+    impl Hash<u64> for Custom {
+        fn hash(&self, state: &mut u64) {
+            *state = self.hash;
+        }
+    }
+
+    #[test]
+    fn test_custom_state() {
+        let custom = Custom { hash: 5 };
+        let mut state = 0;
+        custom.hash(&mut state);
+        assert_eq!(state, 5);
+    }
+}
diff --git a/src/libstd/hash/sip.rs b/src/libstd/hash/sip.rs
new file mode 100644
index 00000000000..ce5e0d6b2ed
--- /dev/null
+++ b/src/libstd/hash/sip.rs
@@ -0,0 +1,519 @@
+// Copyright 2012-2014 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.
+
+/*!
+ * 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 container::Container;
+use io::{IoResult, Writer};
+use iter::Iterator;
+use result::Ok;
+use vec::ImmutableVector;
+
+use super::{Hash, Hasher};
+
+/// `SipState` computes a SipHash 2-4 hash over a stream of bytes.
+pub struct SipState {
+    priv k0: u64,
+    priv k1: u64,
+    priv length: uint, // how many bytes we've processed
+    priv v0: u64,      // hash state
+    priv v1: u64,
+    priv v2: u64,
+    priv v3: u64,
+    priv tail: [u8, ..8], // unprocessed bytes
+    priv ntail: uint,  // how many bytes in tail are valid
+}
+
+// sadly, these macro definitions can't appear later,
+// because they're needed in the following defs;
+// this design could be improved.
+
+macro_rules! u8to64_le (
+    ($buf:expr, $i:expr) =>
+    ($buf[0+$i] as u64 |
+     $buf[1+$i] as u64 << 8 |
+     $buf[2+$i] as u64 << 16 |
+     $buf[3+$i] as u64 << 24 |
+     $buf[4+$i] as u64 << 32 |
+     $buf[5+$i] as u64 << 40 |
+     $buf[6+$i] as u64 << 48 |
+     $buf[7+$i] as u64 << 56)
+)
+
+macro_rules! rotl (
+    ($x:expr, $b:expr) =>
+    (($x << $b) | ($x >> (64 - $b)))
+)
+
+macro_rules! compress (
+    ($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
+    ({
+        $v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0;
+        $v0 = rotl!($v0, 32);
+        $v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2;
+        $v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0;
+        $v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2;
+        $v2 = rotl!($v2, 32);
+    })
+)
+
+impl SipState {
+    /// Create a `SipState` that is keyed off the provided keys.
+    #[inline]
+    pub fn new(key0: u64, key1: u64) -> SipState {
+        let mut state = SipState {
+            k0: key0,
+            k1: key1,
+            length: 0,
+            v0: 0,
+            v1: 0,
+            v2: 0,
+            v3: 0,
+            tail: [ 0, 0, 0, 0, 0, 0, 0, 0 ],
+            ntail: 0,
+        };
+        state.reset();
+        state
+    }
+
+    /// Reset the state back to it's 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;
+    }
+
+    /// Return 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 mut b : u64 = (self.length as u64 & 0xff) << 56;
+
+        if self.ntail > 0 { b |= self.tail[0] as u64 <<  0; }
+        if self.ntail > 1 { b |= self.tail[1] as u64 <<  8; }
+        if self.ntail > 2 { b |= self.tail[2] as u64 << 16; }
+        if self.ntail > 3 { b |= self.tail[3] as u64 << 24; }
+        if self.ntail > 4 { b |= self.tail[4] as u64 << 32; }
+        if self.ntail > 5 { b |= self.tail[5] as u64 << 40; }
+        if self.ntail > 6 { b |= self.tail[6] as u64 << 48; }
+
+        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 Writer for SipState {
+    #[inline]
+    fn write(&mut self, msg: &[u8]) -> IoResult<()> {
+        let length = msg.len();
+        self.length += length;
+
+        let mut needed = 0u;
+
+        if self.ntail != 0 {
+            needed = 8 - self.ntail;
+
+            if length < needed {
+                let mut t = 0;
+                while t < length {
+                    self.tail[self.ntail+t] = msg[t];
+                    t += 1;
+                }
+                self.ntail += length;
+                return Ok(());
+            }
+
+            let mut t = 0;
+            while t < needed {
+                self.tail[self.ntail+t] = msg[t];
+                t += 1;
+            }
+
+            let m = u8to64_le!(self.tail, 0);
+
+            self.v3 ^= m;
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            self.v0 ^= m;
+
+            self.ntail = 0;
+        }
+
+        // Buffered tail is now flushed, process new input.
+        let len = length - needed;
+        let end = len & (!0x7);
+        let left = len & 0x7;
+
+        let mut i = needed;
+        while i < end {
+            let mi = u8to64_le!(msg, i);
+
+            self.v3 ^= mi;
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            self.v0 ^= mi;
+
+            i += 8;
+        }
+
+        let mut t = 0u;
+        while t < left {
+            self.tail[t] = msg[i+t];
+            t += 1
+        }
+        self.ntail = left;
+
+        Ok(())
+    }
+}
+
+/// `Sip` computes the SipHash algorithm from a stream of bytes.
+pub struct SipHasher {
+    priv state: SipState,
+}
+
+impl SipHasher {
+    /// Create a `Sip`.
+    #[inline]
+    pub fn new() -> SipHasher {
+        SipHasher::new_with_keys(0, 0)
+    }
+
+    /// Create a `Sip` that is keyed off the provided keys.
+    #[inline]
+    pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
+        SipHasher {
+            state: SipState::new(key0, key1),
+        }
+    }
+}
+
+impl Hasher<SipState> for SipHasher {
+    #[inline]
+    fn hash<T: Hash<SipState>>(&self, value: &T) -> u64 {
+        let mut state = self.state; // implicitly copy the state.
+        value.hash(&mut state);
+        state.result()
+    }
+}
+
+
+/// Hash a value using the SipHash algorithm.
+#[inline]
+pub fn hash<T: Hash<SipState>>(value: &T) -> u64 {
+    hash_with_keys(0, 0, value)
+}
+
+/// Hash a value with the SipHash algorithm with the provided keys.
+#[inline]
+pub fn hash_with_keys<T: Hash<SipState>>(k0: u64, k1: u64, value: &T) -> u64 {
+    let mut state = SipState::new(k0, k1);
+    value.hash(&mut state);
+    state.result()
+}
+
+#[cfg(test)]
+mod tests {
+    extern crate test;
+    use io::Writer;
+    use iter::Iterator;
+    use num::ToStrRadix;
+    use option::{Some, None};
+    use str::{Str, OwnedStr};
+    use vec::{Vector, ImmutableVector, OwnedVector};
+    use self::test::BenchHarness;
+
+    use super::super::Hash;
+    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 : ~[u8] = ~[];
+        let mut t = 0;
+        let mut state_inc = SipState::new(k0, k1);
+        let mut state_full = SipState::new(k0, k1);
+
+        fn to_hex_str(r: &[u8, ..8]) -> ~str {
+            let mut s = ~"";
+            for b in r.iter() {
+                s.push_str((*b as uint).to_str_radix(16u));
+            }
+            s
+        }
+
+        fn result_bytes(h: u64) -> ~[u8] {
+            ~[(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) -> ~str {
+            let r = result_bytes(h);
+            let mut s = ~"";
+            for b in r.iter() {
+                s.push_str((*b as uint).to_str_radix(16u));
+            }
+            s
+        }
+
+        while t < 64 {
+            debug!("siphash test {}", t);
+            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);
+            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!(f == i && f == v);
+
+            buf.push(t as u8);
+            state_inc.write_u8(t);
+
+            t += 1;
+        }
+    }
+
+    #[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 = (&[1u8], &[0u8, 0], &[0u8]);
+        let w = (&[1u8, 0, 0, 0], &[], &[]);
+
+        assert!(v != w);
+        assert!(hash(&v) != hash(&w));
+    }
+
+    #[bench]
+    fn bench_str(bh: &mut BenchHarness) {
+        let s = "foo";
+        bh.iter(|| {
+            assert_eq!(hash(&s), 16262950014981195938);
+        })
+    }
+
+    struct Compound {
+        x: u8,
+        y: u16,
+        z: ~str,
+    }
+
+    impl<S: Writer> Hash<S> for Compound {
+        #[inline]
+        fn hash(&self, state: &mut S) {
+            self.x.hash(state);
+            self.y.hash(state);
+            self.z.hash(state);
+        }
+    }
+
+    #[bench]
+    fn bench_compound_1(bh: &mut BenchHarness) {
+        let compound = Compound {
+            x: 1,
+            y: 2,
+            z: ~"foobarbaz",
+        };
+        bh.iter(|| {
+            assert_eq!(hash(&compound), 3581836382593270478);
+        })
+    }
+}