Implemented BuildHasher for WyHash

src/final3/mod.rs

@@ -2,4 +2,4 @@ mod functions;
 pub use functions::{make_secret, wyhash, wyrng};
 
 mod traits;
-pub use traits::{WyHash, WyRng};
+pub use traits::{WyHash, WyRng, WyHasherBuilder};

src/final3/traits.rs

@@ -1,8 +1,36 @@
 use crate::final3::functions::{wyhash_core, wyhash_finish, wyrng};
 use crate::v1::functions::{read64, P0, P1, P2, P3};
-use core::hash::Hasher;
+use core::hash::{Hasher, BuildHasher};
 use rand_core::{impls, Error, RngCore, SeedableRng};
 
+/// WyHash hasher builder
+#[derive(Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Copy, Hash)]
+pub struct WyHasherBuilder {
+    seed: u64,
+    secret: [u64; 4],
+}
+
+impl WyHasherBuilder {
+    /// Create hasher builder with a seed
+    pub fn new(seed: u64, secret: [u64; 4]) -> Self {
+        WyHasherBuilder { seed, secret }
+    }
+}
+
+impl Default for WyHasherBuilder {
+    fn default() -> Self {
+        WyHasherBuilder::new(0, [P0, P1, P2, P3])
+    }
+}
+
+impl BuildHasher for WyHasherBuilder {
+    type Hasher = WyHash;
+
+    fn build_hasher(&self) -> Self::Hasher {
+        WyHash::new(self.seed, self.secret)
+    }
+}
+
 /// WyHash hasher
 #[derive(Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Copy, Hash)]
 pub struct WyHash {

src/lib.rs

@@ -112,4 +112,4 @@ pub mod v1;
 /// WyHash version final 3
 pub mod final3;
 pub use crate::final3::{make_secret, wyhash, wyrng};
-pub use crate::final3::{WyHash, WyRng};
+pub use crate::final3::{WyHash, WyRng, WyHasherBuilder};

src/v1/mod.rs

@@ -2,4 +2,4 @@ pub(crate) mod functions;
 pub use functions::{wyhash, wyrng};
 
 mod traits;
-pub use traits::{WyHash, WyRng};
+pub use traits::{WyHash, WyRng, WyHasherBuilder};

src/v1/traits.rs

@@ -1,7 +1,34 @@
 use crate::v1::functions::{mix_with_p0, read64, wyhash_core, wyhash_finish, wyrng};
-use core::hash::Hasher;
+use core::hash::{Hasher, BuildHasher};
 use rand_core::{impls, Error, RngCore, SeedableRng};
 
+/// WyHash hasher builder
+#[derive(Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Copy, Hash)]
+pub struct WyHasherBuilder {
+    seed: u64,
+}
+
+impl WyHasherBuilder {
+    /// Create hasher builder with a seed
+    pub fn new(seed: u64) -> Self {
+        WyHasherBuilder { seed }
+    }
+}
+
+impl Default for WyHasherBuilder {
+    fn default() -> Self {
+        WyHasherBuilder::new(0)
+    }
+}
+
+impl BuildHasher for WyHasherBuilder {
+    type Hasher = WyHash;
+
+    fn build_hasher(&self) -> Self::Hasher {
+        WyHash { h: self.seed, size: 0 }
+    }
+}
+
 /// WyHash hasher
 #[derive(Default, Clone, Copy, Debug, PartialEq, Eq, Ord, PartialOrd, Hash)]
 pub struct WyHash {

tests/integration.rs

@@ -1,6 +1,6 @@
 extern crate core;
 extern crate wyhash;
-use core::hash::Hasher;
+use core::hash::{Hasher, BuildHasher};
 use wyhash::{final3, v1};
 
 #[test]
@@ -21,3 +21,24 @@ fn final3_default_constructed() {
     hasher.write(&[0]);
     assert_eq!(expected, hasher.finish());
 }
+
+#[test]
+fn v1_default_constructed_build_hasher() {
+    let builder = v1::WyHasherBuilder::default();
+    let mut hasher = builder.build_hasher();
+    hasher.write(&[0]);
+    assert_eq!(0x8c73_a8ab_4659_6ae4, hasher.finish());
+}
+
+#[test]
+fn final3_default_constructed_build_hasher() {
+    #[cfg(not(feature = "mum32bit"))]
+    let expected = 0x22a2_d5db_3856_770f;
+    #[cfg(feature = "mum32bit")]
+    let expected = 0x6a2c_d506_62d4_cdf1;
+
+    let builder = final3::WyHasherBuilder::default();
+    let mut hasher = builder.build_hasher();
+    hasher.write(&[0]);
+    assert_eq!(expected, hasher.finish());
+}