Implement Hash for Lua String

src/string.rs

@@ -1,4 +1,5 @@
-use std::borrow::Cow;
+use std::borrow::{Borrow, Cow};
+use std::hash::{Hash, Hasher};
 use std::string::String as StdString;
 use std::{slice, str};
 
@@ -119,6 +120,12 @@ impl<'lua> AsRef<[u8]> for String<'lua> {
     }
 }
 
+impl<'lua> Borrow<[u8]> for String<'lua> {
+    fn borrow(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
 // Lua strings are basically &[u8] slices, so implement PartialEq for anything resembling that.
 //
 // This makes our `String` comparable with `Vec<u8>`, `[u8]`, `&str`, `String` and `mlua::String`
@@ -136,6 +143,14 @@ where
     }
 }
 
+impl<'lua> Eq for String<'lua> {}
+
+impl<'lua> Hash for String<'lua> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.as_bytes().hash(state);
+    }
+}
+
 #[cfg(feature = "serialize")]
 impl<'lua> Serialize for String<'lua> {
     fn serialize<S>(&self, serializer: S) -> StdResult<S::Ok, S::Error>

tests/string.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::HashSet;
 
 use mlua::{Lua, Result, String};
 
@@ -67,3 +68,18 @@ fn test_raw_string() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_string_hash() -> Result<()> {
+    let lua = Lua::new();
+
+    let set: HashSet<String> = lua.load(r#"{"hello", "world", "abc", 321}"#).eval()?;
+    assert_eq!(set.len(), 4);
+    assert!(set.contains(b"hello".as_ref()));
+    assert!(set.contains(b"world".as_ref()));
+    assert!(set.contains(b"abc".as_ref()));
+    assert!(set.contains(b"321".as_ref()));
+    assert!(!set.contains(b"Hello".as_ref()));
+
+    Ok(())
+}