Unify the standard properties checks in diff.

Instead of copy+pasting them into each compare function, we now call a shared function from a handful of places.

src/types/element.rs

@@ -4,6 +4,7 @@ use super::greater_element::GreaterBlock;
 use super::greater_element::PlainList;
 use super::greater_element::PropertyDrawer;
 use super::greater_element::Table;
+use super::lesser_element::BabelCall;
 use super::lesser_element::Clock;
 use super::lesser_element::Comment;
 use super::lesser_element::CommentBlock;
@@ -45,7 +46,7 @@ pub enum Element<'s> {
     FixedWidthArea(FixedWidthArea<'s>),
     HorizontalRule(HorizontalRule<'s>),
     Keyword(Keyword<'s>),
-    BabelCall(Keyword<'s>),
+    BabelCall(BabelCall<'s>),
     LatexEnvironment(LatexEnvironment<'s>),
 }
 

src/types/get_standard_properties.rs

@@ -2,9 +2,7 @@ use super::StandardProperties;
 
 pub trait GetStandardProperties<'s> {
     // TODO: Can I eliminate this dynamic dispatch, perhaps using nominal generic structs? Low prioritiy since this is not used during parsing.
-    fn get_standard_properties(&'s self) -> &'s dyn StandardProperties
-    where
-        Self: Sized;
+    fn get_standard_properties(&'s self) -> &'s dyn StandardProperties;
 }
 
 impl<'s, I: StandardProperties<'s>> GetStandardProperties<'s> for I {

src/types/lesser_element.rs

@@ -91,6 +91,13 @@ pub struct Keyword<'s> {
     pub value: &'s str,
 }
 
+#[derive(Debug)]
+pub struct BabelCall<'s> {
+    pub source: &'s str,
+    pub key: &'s str,
+    pub value: &'s str,
+}
+
 #[derive(Debug)]
 pub struct LatexEnvironment<'s> {
     pub source: &'s str,
@@ -187,6 +194,12 @@ impl<'s> StandardProperties<'s> for Keyword<'s> {
     }
 }
 
+impl<'s> StandardProperties<'s> for BabelCall<'s> {
+    fn get_source(&'s self) -> &'s str {
+        self.source
+    }
+}
+
 impl<'s> StandardProperties<'s> for LatexEnvironment<'s> {
     fn get_source(&'s self) -> &'s str {
         self.source

src/types/mod.rs

@@ -27,6 +27,7 @@ pub use greater_element::PlainListItem;
 pub use greater_element::PropertyDrawer;
 pub use greater_element::Table;
 pub use greater_element::TableRow;
+pub use lesser_element::BabelCall;
 pub use lesser_element::Clock;
 pub use lesser_element::Comment;
 pub use lesser_element::CommentBlock;