1 files changed, 121 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs
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+//! A Rust implementation of the [XXHash] algorithm.
+//!
+//! [XXHash]: https://github.com/Cyan4973/xxHash
+//!
+//! ### With a fixed seed
+//!
+//! ```rust
+//! use std::hash::BuildHasherDefault;
+//! use std::collections::HashMap;
+//! use twox_hash::XxHash64;
+//!
+//! let mut hash: HashMap<_, _, BuildHasherDefault<XxHash64>> = Default::default();
+//! hash.insert(42, "the answer");
+//! assert_eq!(hash.get(&42), Some(&"the answer"));
+//! ```
+//!
+//! ### With a random seed
+//!
+//! ```rust
+//! use std::collections::HashMap;
+//! use twox_hash::RandomXxHashBuilder64;
+//!
+//! let mut hash: HashMap<_, _, RandomXxHashBuilder64> = Default::default();
+//! hash.insert(42, "the answer");
+//! assert_eq!(hash.get(&42), Some(&"the answer"));
+//! ```
+
+#![no_std]
+
+extern crate alloc;
+
+#[cfg(test)]
+extern crate std;
+
+use core::{marker::PhantomData, mem};
+
+mod sixty_four;
+mod thirty_two;
+pub mod xxh3;
+
+#[cfg(feature = "std")]
+mod std_support;
+#[cfg(feature = "std")]
+pub use std_support::sixty_four::RandomXxHashBuilder64;
+#[cfg(feature = "std")]
+pub use std_support::thirty_two::RandomXxHashBuilder32;
+#[cfg(feature = "std")]
+pub use std_support::xxh3::{
+    RandomHashBuilder128 as RandomXxh3HashBuilder128,
+    RandomHashBuilder64 as RandomXxh3HashBuilder64,
+};
+
+#[cfg(feature = "digest")]
+mod digest_support;
+
+#[cfg(feature = "digest_0_9")]
+mod digest_0_9_support;
+
+#[cfg(feature = "digest_0_10")]
+mod digest_0_10_support;
+
+pub use crate::sixty_four::XxHash64;
+pub use crate::thirty_two::XxHash32;
+pub use crate::xxh3::{Hash128 as Xxh3Hash128, Hash64 as Xxh3Hash64};
+
+/// A backwards compatibility type alias. Consider directly using
+/// `XxHash64` instead.
+pub type XxHash = XxHash64;
+
+#[cfg(feature = "std")]
+/// A backwards compatibility type alias. Consider directly using
+/// `RandomXxHashBuilder64` instead.
+pub type RandomXxHashBuilder = RandomXxHashBuilder64;
+
+/// An unaligned buffer with iteration support for `UnalignedItem`.
+struct UnalignedBuffer<'a, T> {
+    buf: &'a [u8],
+    phantom: PhantomData<T>,
+}
+
+/// Types implementing this trait must be transmutable from a `*const
+/// u8` to `*const Self` at any possible alignment.
+///
+/// The intent is to use this with only primitive integer types (and
+/// tightly-packed arrays of those integers).
+#[allow(clippy::missing_safety_doc)]
+unsafe trait UnalignedItem {}
+
+unsafe impl UnalignedItem for [u64; 4] {}
+unsafe impl UnalignedItem for [u32; 4] {}
+unsafe impl UnalignedItem for u64 {}
+unsafe impl UnalignedItem for u32 {}
+
+impl<'a, T: UnalignedItem> UnalignedBuffer<'a, T> {
+    #[inline]
+    fn new(buf: &'a [u8]) -> Self {
+        Self {
+            buf,
+            phantom: PhantomData,
+        }
+    }
+
+    #[inline]
+    fn remaining(&self) -> &[u8] {
+        self.buf
+    }
+}
+
+impl<'a, T: UnalignedItem> Iterator for UnalignedBuffer<'a, T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let size = mem::size_of::<T>();
+        self.buf.get(size..).map(|remaining| {
+            // `self.buf` has at least `size` bytes that can be read as `T`.
+            let result = unsafe { (self.buf.as_ptr() as *const T).read_unaligned() };
+            self.buf = remaining;
+            result
+        })
+    }
+}