Implement the new fields for entity.

src/parser/entity.rs

@@ -28,7 +28,7 @@ pub(crate) fn entity<'b, 'g, 'r, 's>(
     let (remaining, _) = tag("\\")(input)?;
     let (remaining, (entity_definition, entity_name, use_brackets)) = name(context, 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);
@@ -43,6 +43,7 @@ pub(crate) fn entity<'b, 'g, 'r, 's>(
             ascii: entity_definition.ascii,
             utf8: entity_definition.utf8,
             use_brackets,
+            post_blank: post_blank.map(Into::<&str>::into),
         },
     ))
 }

src/types/object.rs

@@ -187,6 +187,7 @@ pub struct Entity<'s> {
     // Skipping latin1 because it is detrimental to the future. If anyone out there is using latin1, take a long look in the mirror and change your ways.
     pub utf8: &'s str,
     pub use_brackets: bool,
+    pub post_blank: Option<&'s str>,
 }
 
 #[derive(Debug)]
@@ -740,11 +741,15 @@ impl<'s> StandardProperties<'s> for Entity<'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.")
     }
 }