bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'lib/non-hash/src/lib.rs')
-rw-r--r--lib/non-hash/src/lib.rs104
1 files changed, 104 insertions, 0 deletions
diff --git a/lib/non-hash/src/lib.rs b/lib/non-hash/src/lib.rs
new file mode 100644
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+++ b/lib/non-hash/src/lib.rs
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+//! A non-hashing [`Hasher`] implementation.
+
+#![deny(clippy::pedantic, missing_debug_implementations, missing_docs, rust_2018_idioms)]
+
+use std::{
+ hash::{BuildHasher, Hasher},
+ marker::PhantomData,
+};
+
+/// A [`std::collections::HashMap`] with [`NoHashHasherBuilder`].
+pub type NoHashHashMap<K, V> = std::collections::HashMap<K, V, NoHashHasherBuilder<K>>;
+
+/// A [`std::collections::HashSet`] with [`NoHashHasherBuilder`].
+pub type NoHashHashSet<K> = std::collections::HashSet<K, NoHashHasherBuilder<K>>;
+
+/// A hasher builder for [`NoHashHasher`].
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct NoHashHasherBuilder<T>(PhantomData<T>);
+
+impl<T> Default for NoHashHasherBuilder<T> {
+ fn default() -> Self {
+ Self(PhantomData)
+ }
+}
+
+/// Types for which an acceptable hash function is to return itself.
+///
+/// This trait is implemented by sufficiently-small integer types. It should only be implemented for
+/// foreign types that are newtypes of these types. If it is implemented on more complex types,
+/// hashing will panic.
+pub trait NoHashHashable {}
+
+impl NoHashHashable for u8 {}
+impl NoHashHashable for u16 {}
+impl NoHashHashable for u32 {}
+impl NoHashHashable for u64 {}
+impl NoHashHashable for usize {}
+
+impl NoHashHashable for i8 {}
+impl NoHashHashable for i16 {}
+impl NoHashHashable for i32 {}
+impl NoHashHashable for i64 {}
+impl NoHashHashable for isize {}
+
+/// A hasher for [`NoHashHashable`] types.
+#[derive(Debug)]
+pub struct NoHashHasher(u64);
+
+impl<T: NoHashHashable> BuildHasher for NoHashHasherBuilder<T> {
+ type Hasher = NoHashHasher;
+ fn build_hasher(&self) -> Self::Hasher {
+ NoHashHasher(0)
+ }
+}
+
+impl Hasher for NoHashHasher {
+ fn finish(&self) -> u64 {
+ self.0
+ }
+
+ fn write(&mut self, _: &[u8]) {
+ unimplemented!("NoHashHasher should only be used for hashing sufficiently-small integer types and their newtypes")
+ }
+
+ fn write_u8(&mut self, i: u8) {
+ self.0 = i as u64;
+ }
+
+ fn write_u16(&mut self, i: u16) {
+ self.0 = i as u64;
+ }
+
+ fn write_u32(&mut self, i: u32) {
+ self.0 = i as u64;
+ }
+
+ fn write_u64(&mut self, i: u64) {
+ self.0 = i;
+ }
+
+ fn write_usize(&mut self, i: usize) {
+ self.0 = i as u64;
+ }
+
+ fn write_i8(&mut self, i: i8) {
+ self.0 = i as u64;
+ }
+
+ fn write_i16(&mut self, i: i16) {
+ self.0 = i as u64;
+ }
+
+ fn write_i32(&mut self, i: i32) {
+ self.0 = i as u64;
+ }
+
+ fn write_i64(&mut self, i: i64) {
+ self.0 = i as u64;
+ }
+
+ fn write_isize(&mut self, i: isize) {
+ self.0 = i as u64;
+ }
+}