Add the code structure for diary sexp.

src/compare/diff.rs

@@ -4,6 +4,7 @@ use super::util::assert_name;
 use crate::parser::Clock;
 use crate::parser::Comment;
 use crate::parser::CommentBlock;
+use crate::parser::DiarySexp;
 use crate::parser::Document;
 use crate::parser::DocumentElement;
 use crate::parser::Drawer;
@@ -215,6 +216,7 @@ fn compare_element<'s>(
         Element::ExportBlock(obj) => compare_export_block(source, emacs, obj),
         Element::SrcBlock(obj) => compare_src_block(source, emacs, obj),
         Element::Clock(obj) => compare_clock(source, emacs, obj),
+        Element::DiarySexp(obj) => compare_diary_sexp(source, emacs, obj),
     }
 }
 
@@ -702,3 +704,26 @@ fn compare_clock<'s>(
         children: Vec::new(),
     })
 }
+
+fn compare_diary_sexp<'s>(
+    source: &'s str,
+    emacs: &'s Token<'s>,
+    rust: &'s DiarySexp<'s>,
+) -> Result<DiffResult, Box<dyn std::error::Error>> {
+    let mut this_status = DiffStatus::Good;
+    let emacs_name = "diary-sexp";
+    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: Vec::new(),
+    })
+}