Fix the implementation of post.

src/parser/text_markup.rs

@@ -1,6 +1,10 @@
 use nom::branch::alt;
 use nom::bytes::complete::tag;
+use nom::character::complete::line_ending;
+use nom::character::complete::one_of;
+use nom::character::complete::space0;
 use nom::combinator::peek;
+use nom::combinator::recognize;
 use nom::combinator::verify;
 use nom::multi::many_till;
 use nom::sequence::terminated;
@@ -43,6 +47,7 @@ pub fn text_markup<'r, 's>(
 
     // TODO: Sometimes its plain text, not objects
     let (remaining, close) = text_markup_end_specialized(context, remaining)?;
+    let (remaining, _trailing_whitespace) = space0(remaining)?;
 
     let source = get_consumed(input, remaining);
 
@@ -71,22 +76,8 @@ pub fn pre<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, ()>
 
 #[tracing::instrument(ret, level = "debug")]
 pub fn post<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, ()> {
-    let document_root = context.get_document_root().unwrap();
-    let preceding_character = get_one_before(document_root, input)
-        .map(|slice| slice.chars().next())
-        .flatten();
-    match preceding_character {
-        // If None, we are at the start of the file which is technically the beginning of a line.
-        None | Some('\r') | Some('\n') | Some(' ') | Some('\t') | Some('-') | Some('(')
-        | Some('{') | Some('\'') | Some('"') => {}
-        Some(_) => {
-            // Not at start of line, cannot be a heading
-            return Err(nom::Err::Error(CustomError::MyError(MyError(
-                "Not a valid pre character for text markup.",
-            ))));
-        }
-    };
-    Ok((input, ()))
+    let (remaining, _) = alt((recognize(one_of(" \r\n\t-.,;:!?')}[\"")), line_ending))(input)?;
+    Ok((remaining, ()))
 }
 
 #[tracing::instrument(ret, level = "debug")]