Implement typed RLV protocol parser (#78)

crates/libremetaverse-types/src/compat.rs

@@ -1153,7 +1153,64 @@ impl<T> Future for AsyncEnumerableNext<T> {
 
 pub struct ImmutableDictionary<TKey, TValue>(pub PhantomData<fn(TKey, TValue)>);
 
-pub struct ImmutableList<T>(pub PhantomData<fn(T)>);
+/// Read-only, cheaply clonable snapshot corresponding to
+/// `System.Collections.Immutable.ImmutableList<T>`.
+#[derive(Clone, Debug, Default, Eq, Hash, PartialEq)]
+pub struct ImmutableList<T>(Arc<[T]>);
+
+impl<T> ImmutableList<T> {
+    /// Creates an immutable snapshot from owned values.
+    #[must_use]
+    pub fn from_vec(values: Vec<T>) -> Self {
+        Self(values.into())
+    }
+
+    /// Returns the snapshot as a slice.
+    #[must_use]
+    pub fn as_slice(&self) -> &[T] {
+        &self.0
+    }
+
+    /// Returns the number of values in the snapshot.
+    #[must_use]
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Returns whether the snapshot contains no values.
+    #[must_use]
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    /// Iterates over the snapshot.
+    pub fn iter(&self) -> std::slice::Iter<'_, T> {
+        self.0.iter()
+    }
+}
+
+impl<T> From<Vec<T>> for ImmutableList<T> {
+    fn from(values: Vec<T>) -> Self {
+        Self::from_vec(values)
+    }
+}
+
+impl<T> std::ops::Deref for ImmutableList<T> {
+    type Target = [T];
+
+    fn deref(&self) -> &Self::Target {
+        self.as_slice()
+    }
+}
+
+impl<'a, T> IntoIterator for &'a ImmutableList<T> {
+    type Item = &'a T;
+    type IntoIter = std::slice::Iter<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
 
 pub struct ICollection;