Add form 6 of LaTeX fragment.

src/parser/latex_fragment.rs

@@ -34,6 +34,7 @@ pub fn latex_fragment<'r, 's>(
         parser_with_context!(escaped_bracket_fragment)(context),
         parser_with_context!(double_dollar_fragment)(context),
         parser_with_context!(dollar_char_fragment)(context),
+        parser_with_context!(bordered_dollar_fragment)(context),
     ))(input)?;
     let (remaining, _) = space0(remaining)?;
     let source = get_consumed(input, remaining);
@@ -176,3 +177,54 @@ pub fn post<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, ()
     let (remaining, _) = alt((recognize(one_of(" \t-.,;:!?'\"")), line_ending))(input)?;
     Ok((remaining, ()))
 }
+
+#[tracing::instrument(ret, level = "debug")]
+fn bordered_dollar_fragment<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, &'s str> {
+    let (_, _) = pre(context, input)?;
+    let (remaining, _) = tag("$")(input)?;
+    // TODO: I'm assuming I should be peeking at the borders but the documentation is not clear. Test to figure out.
+    let (_, _) = peek(parser_with_context!(open_border)(context))(remaining)?;
+
+    // TODO: As an optimization it would be nice to exit early upon hitting the 3rd line break
+    let (remaining, _) = verify(
+        recognize(many_till(
+            anychar,
+            peek(alt((
+                parser_with_context!(exit_matcher_parser)(context),
+                tag("$"),
+            ))),
+        )),
+        |body: &str| body.lines().take(4).count() <= 3,
+    )(remaining)?;
+
+    let (_, _) = peek(parser_with_context!(close_border)(context))(remaining)?;
+    let (remaining, _) = tag("$")(remaining)?;
+    let (_, _) = peek(parser_with_context!(post)(context))(remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((remaining, source))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn open_border<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    recognize(verify(none_of(".,;$"), |c| !c.is_whitespace()))(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn close_border<'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 {
+        Some(c) if !c.is_whitespace() && !".,;$".contains(c) => Ok((input, ())),
+        _ => {
+            return Err(nom::Err::Error(CustomError::MyError(MyError(
+                "Not a valid pre character for dollar char fragment.",
+            ))));
+        }
+    }
+}