Make use of NoHash hashing for FileId and CrateId

2 files changed, 88 insertions, 0 deletions

diff --git a/crates/stdx/src/hash.rs b/crates/stdx/src/hash.rs
new file mode 100644
index 00000000000..bf7d71eb03a
--- /dev/null
+++ b/crates/stdx/src/hash.rs
@@ -0,0 +1,87 @@
+use std::{
+    hash::{BuildHasher, Hasher},
+    marker::PhantomData,
+};
+
+pub type NoHashHashMap<K, V> = std::collections::HashMap<K, V, NoHashHasherBuilder<K>>;
+pub type NoHashHashSet<K> = std::collections::HashSet<K, NoHashHasherBuilder<K>>;
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct NoHashHasherBuilder<T>(PhantomData<T>);
+
+impl<T> Default for NoHashHasherBuilder<T> {
+    fn default() -> Self {
+        Self(Default::default())
+    }
+}
+
+pub trait NoHashHashable {}
+impl NoHashHashable for usize {}
+impl NoHashHashable for u32 {}
+
+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 primitive integers")
+    }
+
+    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 as u64;
+    }
+
+    fn write_u128(&mut self, i: u128) {
+        self.0 = i as u64;
+    }
+
+    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_i128(&mut self, i: i128) {
+        self.0 = i as u64;
+    }
+
+    fn write_isize(&mut self, i: isize) {
+        self.0 = i as u64;
+    }
+}
diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index b4d45206c44..51e109798d1 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -7,6 +7,7 @@ use std::{cmp::Ordering, ops, time::Instant};
 use std::{io as sio, iter};
 
 mod macros;
+pub mod hash;
 pub mod process;
 pub mod panic_context;
 pub mod non_empty_vec;