Implement IntoIterator for &Attributes and Extend for Attributes (#386)

The original implementation of Attributes had an `iter` method but it
did not implement `FromIterator` for `&Attributes`, making it so you
couldn't use `for (key, value) in &attributes` and had to use `for (key,
value) in attributes.iter()`. This changes that.

Additionally, `Extend` is a nice quality of life trait for containers so
it's implemented here.

rbx_types/CHANGELOG.md

@@ -1,10 +1,16 @@
 # rbx_types Changelog
 
 ## Unreleased Changes
+* Implement `IntoIterator` for `&Attributes`. ([#386])
+* Implement `Extend<(String, Variant)>` for `Attributes`. ([#386])
+
+[#386]: https://github.com/rojo-rbx/rbx-dom/pull/386
 
 ## 1.8.0 (2024-01-16)
 * Add `len` and `is_empty` methods to `Attributes` struct. ([#377])
 
+[#377]: https://github.com/rojo-rbx/rbx-dom/pull/377
+
 ## 1.7.0 (2023-10-03)
 * Implemented `FromStr` for `TerrainMaterials`. ([#354])
 * `MaterialColorsError` and `UniqueIdError` are no longer publicly exposed. ([#355])
@@ -15,7 +21,6 @@
 [#355]: https://github.com/rojo-rbx/rbx-dom/pull/355
 [#358]: https://github.com/rojo-rbx/rbx-dom/pull/358
 [#363]: https://github.com/rojo-rbx/rbx-dom/pull/363
-[#377]: https://github.com/rojo-rbx/rbx-dom/pull/377
 
 ## 1.6.0 (2023-08-09)
 * Added support for `UniqueId` values. ([#271])

rbx_types/src/attributes/mod.rs

@@ -75,8 +75,11 @@ impl Attributes {
     }
 
     /// Returns an iterator of borrowed attributes.
-    pub fn iter(&self) -> impl Iterator<Item = (&String, &Variant)> {
-        self.data.iter()
+    #[inline]
+    pub fn iter(&self) -> AttributesIter<'_> {
+        AttributesIter {
+            iter: self.data.iter(),
+        }
     }
 
     /// Returns the number of attributes.
@@ -92,6 +95,12 @@ impl Attributes {
     }
 }
 
+impl Extend<(String, Variant)> for Attributes {
+    fn extend<T: IntoIterator<Item = (String, Variant)>>(&mut self, iter: T) {
+        self.data.extend(iter)
+    }
+}
+
 impl IntoIterator for Attributes {
     type IntoIter = AttributesIntoIter;
     type Item = (String, Variant);
@@ -103,6 +112,17 @@ impl IntoIterator for Attributes {
     }
 }
 
+impl<'a> IntoIterator for &'a Attributes {
+    type IntoIter = AttributesIter<'a>;
+    type Item = (&'a String, &'a Variant);
+
+    fn into_iter(self) -> Self::IntoIter {
+        AttributesIter {
+            iter: self.data.iter(),
+        }
+    }
+}
+
 impl FromIterator<(String, Variant)> for Attributes {
     fn from_iter<T: IntoIterator<Item = (String, Variant)>>(iter: T) -> Self {
         Self {
@@ -125,6 +145,20 @@ impl Iterator for AttributesIntoIter {
     }
 }
 
+/// A borrowed iterator over the entries of an `Attributes`.
+/// This is created by [`Attributes::iter`].
+pub struct AttributesIter<'a> {
+    iter: btree_map::Iter<'a, String, Variant>,
+}
+
+impl<'a> Iterator for AttributesIter<'a> {
+    type Item = (&'a String, &'a Variant);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;