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/compare/util.rs

@@ -1,4 +1,6 @@
+use super::elisp_fact::GetElispFact;
 use super::sexp::Token;
+use crate::types::GetStandardProperties;
 use crate::types::StandardProperties;
 
 /// Check if the child string slice is a slice of the parent string slice.
@@ -24,10 +26,24 @@ fn get_rust_byte_offsets<'s, S: StandardProperties<'s> + ?Sized>(
     (offset, end)
 }
 
-pub(crate) fn assert_name<'s>(
+pub(crate) fn compare_standard_properties<
+    's,
+    S: GetStandardProperties<'s> + GetElispFact<'s> + ?Sized,
+>(
+    original_document: &'s str,
     emacs: &'s Token<'s>,
-    name: &str,
+    rust: &'s S,
 ) -> Result<(), Box<dyn std::error::Error>> {
+    assert_name(emacs, rust.get_elisp_fact().get_elisp_name())?;
+    assert_bounds(original_document, emacs, rust.get_standard_properties())?;
+    Ok(())
+}
+
+pub(crate) fn assert_name<'s, S: AsRef<str>>(
+    emacs: &'s Token<'s>,
+    name: S,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let name = name.as_ref();
     let children = emacs.as_list()?;
     let first_child = children
         .first()
@@ -35,7 +51,7 @@ pub(crate) fn assert_name<'s>(
         .as_atom()?;
     if first_child != name {
         Err(format!(
-            "Expected a {expected} cell, but found a {found} cell.",
+            "AST node name mismatch. Expected a (rust) {expected} cell, but found a (emacs) {found} cell.",
             expected = name,
             found = first_child
         ))?;