Implement the horizontal rule parser.

src/compare/diff.rs

@@ -16,6 +16,7 @@ use crate::parser::FixedWidthArea;
 use crate::parser::FootnoteDefinition;
 use crate::parser::GreaterBlock;
 use crate::parser::Heading;
+use crate::parser::HorizontalRule;
 use crate::parser::Paragraph;
 use crate::parser::PlainList;
 use crate::parser::PlainListItem;
@@ -221,6 +222,7 @@ fn compare_element<'s>(
         Element::DiarySexp(obj) => compare_diary_sexp(source, emacs, obj),
         Element::Planning(obj) => compare_planning(source, emacs, obj),
         Element::FixedWidthArea(obj) => compare_fixed_width_area(source, emacs, obj),
+        Element::HorizontalRule(obj) => compare_horizontal_rule(source, emacs, obj),
     }
 }
 
@@ -778,3 +780,27 @@ fn compare_fixed_width_area<'s>(
         children: child_status,
     })
 }
+
+fn compare_horizontal_rule<'s>(
+    source: &'s str,
+    emacs: &'s Token<'s>,
+    rust: &'s HorizontalRule<'s>,
+) -> Result<DiffResult, Box<dyn std::error::Error>> {
+    let child_status = Vec::new();
+    let mut this_status = DiffStatus::Good;
+    let emacs_name = "horizontal-rule";
+    if assert_name(emacs, emacs_name).is_err() {
+        this_status = DiffStatus::Bad;
+    }
+
+    if assert_bounds(source, emacs, rust).is_err() {
+        this_status = DiffStatus::Bad;
+    }
+
+    Ok(DiffResult {
+        status: this_status,
+        name: emacs_name.to_owned(),
+        message: None,
+        children: child_status,
+    })
+}