const new for SendPropIdentifier

src/consthash.rs

@@ -0,0 +1,46 @@
+pub struct ConstFnvHash(u64);
+
+impl ConstFnvHash {
+    pub const fn new() -> Self {
+        Self(0xcbf29ce484222325)
+    }
+
+    pub const fn push_string(self, str: &str) -> Self {
+        self.update(str.as_bytes()).update(&[0xff])
+    }
+
+    pub const fn update(self, bytes: &[u8]) -> Self {
+        let Self(mut hash) = self;
+
+        let mut i = 0;
+        while i < bytes.len() {
+            let byte = bytes[i];
+            hash = hash ^ (byte as u64);
+            hash = hash.wrapping_mul(0x100000001b3);
+            i += 1;
+        }
+
+        Self(hash)
+    }
+
+    pub const fn finish(self) -> u64 {
+        self.0
+    }
+}
+
+#[test]
+fn test_const_fnv() {
+    use fnv::FnvHasher;
+    use std::hash::Hash;
+    use std::hash::Hasher;
+
+    let mut hasher = FnvHasher::default();
+    "foobar".hash(&mut hasher);
+    "another input".hash(&mut hasher);
+    let hash = hasher.finish();
+
+    let hasher = ConstFnvHash::new();
+    let hasher = hasher.push_string("foobar");
+    let hasher = hasher.push_string("another input");
+    assert_eq!(hasher.finish(), hash);
+}

src/demo/sendprop.rs

@@ -6,16 +6,15 @@ use crate::{ParseError, ReadResult, Result, Stream};
 
 use super::packet::datatable::ParseSendTable;
 use super::vector::{Vector, VectorXY};
+use crate::consthash::ConstFnvHash;
 use crate::demo::message::stringtable::log_base2;
 use crate::demo::packet::datatable::SendTableName;
 use crate::demo::parser::MalformedSendPropDefinitionError;
 use parse_display::Display;
 use std::cmp::min;
 use std::convert::{TryFrom, TryInto};
-
-use fnv::FnvHasher;
 use std::fmt;
-use std::hash::{Hash, Hasher};
+use std::hash::Hash;
 use std::rc::Rc;
 
 #[derive(
@@ -766,10 +765,8 @@ impl<'a> TryFrom<&'a SendPropValue> for &'a [SendPropValue] {
 pub struct SendPropIdentifier(u64);
 
 impl SendPropIdentifier {
-    pub fn new(table: &str, prop: &str) -> Self {
-        let mut hasher = FnvHasher::default();
-        table.hash(&mut hasher);
-        prop.hash(&mut hasher);
+    pub const fn new(table: &str, prop: &str) -> Self {
+        let hasher = ConstFnvHash::new().push_string(table).push_string(prop);
         SendPropIdentifier(hasher.finish())
     }
 }

src/lib.rs

@@ -9,5 +9,6 @@ pub use crate::demo::{
     Demo, Stream,
 };
 
+pub(crate) mod consthash;
 pub mod demo;
 mod nullhasher;