Implement the new fields for latex fragment.

src/parser/latex_fragment.rs

@@ -39,7 +39,7 @@ pub(crate) fn latex_fragment<'b, 'g, 'r, 's>(
         parser_with_context!(bordered_dollar_fragment)(context),
     ))(input)?;
     let value = get_consumed(input, remaining);
-    let (remaining, _trailing_whitespace) =
+    let (remaining, post_blank) =
         maybe_consume_object_trailing_whitespace_if_not_exiting(context, remaining)?;
     let source = get_consumed(input, remaining);
     Ok((
@@ -47,6 +47,7 @@ pub(crate) fn latex_fragment<'b, 'g, 'r, 's>(
         LatexFragment {
             source: source.into(),
             value: value.into(),
+            post_blank: post_blank.map(Into::<&str>::into),
         },
     ))
 }

src/types/object.rs

@@ -194,6 +194,7 @@ pub struct Entity<'s> {
 pub struct LatexFragment<'s> {
     pub source: &'s str,
     pub value: &'s str,
+    pub post_blank: Option<&'s str>,
 }
 
 #[derive(Debug)]
@@ -759,11 +760,15 @@ impl<'s> StandardProperties<'s> for LatexFragment<'s> {
     }
 
     fn get_contents<'b>(&'b self) -> Option<&'s str> {
-        todo!()
+        None
     }
 
     fn get_post_blank(&self) -> PostBlank {
-        todo!()
+        self.post_blank
+            .map(|post_blank| post_blank.chars().count())
+            .unwrap_or(0)
+            .try_into()
+            .expect("Too much post-blank to fit into a PostBlank.")
     }
 }