Identified the problem.

The issue is plain text is eating the line break so paragraph is failing since it expects a line break at the end.

src/parser/document.rs

@@ -83,8 +83,7 @@ pub fn document(input: &str) -> Res<&str, Document> {
     let section_matcher = parser_with_context!(section)(&document_context);
     let heading_matcher = parser_with_context!(heading)(&document_context);
     let (remaining, zeroth_section) = opt(section_matcher)(input)?;
-    // let (remaining, children) = many0(heading_matcher)(remaining)?;
-    let children = Vec::new();
+    let (remaining, children) = many0(heading_matcher)(remaining)?;
     let source = get_consumed(input, remaining);
     Ok((
         remaining,

src/parser/element.rs

@@ -24,6 +24,7 @@ impl<'s> Source<'s> for Element<'s> {
     }
 }
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn element<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Element<'s>> {
     let non_paragraph_matcher = parser_with_context!(non_paragraph_element)(context);
     let paragraph_matcher = parser_with_context!(paragraph)(context);

src/parser/object.rs

@@ -39,6 +39,7 @@ impl<'s> Source<'s> for Object<'s> {
     }
 }
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn standard_set_object<'r, 's>(
     context: Context<'r, 's>,
     input: &'s str,

src/parser/paragraph.rs

@@ -19,6 +19,7 @@ use super::util::get_consumed;
 use super::util::trailing_whitespace;
 use super::Context;
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn paragraph<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Paragraph<'s>> {
     let parser_context =
         context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
@@ -35,6 +36,7 @@ pub fn paragraph<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s st
     Ok((remaining, Paragraph { source, children }))
 }
 
+#[tracing::instrument(ret, level = "debug")]
 fn paragraph_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
     let non_paragraph_element_matcher = parser_with_context!(non_paragraph_element)(context);
     alt((

src/parser/parser_context.rs

@@ -8,6 +8,7 @@ use super::error::MyError;
 use super::error::Res;
 use super::list::List;
 use super::list::Node;
+use super::util::always_fail;
 use super::Context;
 
 type Matcher = dyn for<'r, 's> Fn(Context<'r, 's>, &'s str) -> Res<&'s str, &'s str>;
@@ -64,20 +65,25 @@ impl<'r, 's> ContextTree<'r, 's> {
             return at_end_of_file;
         }
 
+        let blocked_context =
+            self.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
+                exit_matcher: ChainBehavior::IgnoreParent(Some(&always_fail)),
+            }));
+
         for current_node in self.iter() {
             let context_element = current_node.get_data();
             match context_element {
                 ContextElement::ExitMatcherNode(exit_matcher) => {
                     match exit_matcher.exit_matcher {
                         ChainBehavior::AndParent(Some(matcher)) => {
-                            let local_result = matcher(self, i);
+                            let local_result = matcher(&blocked_context, i);
                             if local_result.is_ok() {
                                 return local_result;
                             }
                         }
                         ChainBehavior::AndParent(None) => {}
                         ChainBehavior::IgnoreParent(Some(matcher)) => {
-                            let local_result = matcher(self, i);
+                            let local_result = matcher(&blocked_context, i);
                             if local_result.is_ok() {
                                 return local_result;
                             }

src/parser/plain_list.rs

@@ -25,7 +25,7 @@ use nom::multi::many0;
 use nom::multi::many_till;
 use nom::sequence::tuple;
 
-#[allow(dead_code)]
+#[tracing::instrument(ret, level = "debug")]
 pub fn plain_list<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, PlainList<'s>> {
     let (remaining, first_item) = plain_list_item(context, input)?;
     let plain_list_item_matcher = parser_with_context!(plain_list_item)(context);
@@ -41,7 +41,7 @@ pub fn plain_list<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s s
     Ok((remaining, PlainList { source, children }))
 }
 
-#[allow(dead_code)]
+#[tracing::instrument(ret, level = "debug")]
 pub fn plain_list_item<'r, 's>(
     context: Context<'r, 's>,
     input: &'s str,
@@ -72,6 +72,7 @@ pub fn plain_list_item<'r, 's>(
     ))
 }
 
+#[tracing::instrument(ret, level = "debug")]
 fn bullet<'s>(i: &'s str) -> Res<&'s str, &'s str> {
     alt((
         tag("*"),
@@ -81,10 +82,12 @@ fn bullet<'s>(i: &'s str) -> Res<&'s str, &'s str> {
     ))(i)
 }
 
+#[tracing::instrument(ret, level = "debug")]
 fn counter<'s>(i: &'s str) -> Res<&'s str, &'s str> {
     alt((recognize(one_of("abcdefghijklmnopqrstuvwxyz")), digit1))(i)
 }
 
+#[tracing::instrument(ret, level = "debug")]
 fn plain_list_item_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
     let plain_list_item_matcher = parser_with_context!(plain_list_item)(context);
     let line_indented_lte_matcher = parser_with_context!(line_indented_lte)(context);
@@ -95,6 +98,7 @@ fn plain_list_item_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<
     ))(input)
 }
 
+#[tracing::instrument(ret, level = "debug")]
 fn line_indented_lte<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
     let current_item_indent_level: &usize =
         get_context_item_indent(context).ok_or(nom::Err::Error(CustomError::MyError(MyError(

src/parser/plain_text.rs

@@ -7,6 +7,7 @@ use super::error::Res;
 use super::object::PlainText;
 use super::Context;
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn plain_text<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, PlainText<'s>> {
     if input.len() == 0 {
         return Err(nom::Err::Error(CustomError::MyError(MyError(

src/parser/util.rs

@@ -71,16 +71,19 @@ pub fn get_consumed<'s>(input: &'s str, remaining: &'s str) -> &'s str {
 /// A line containing only whitespace and then a line break
 ///
 /// It is up to the caller to ensure this is called at the start of a line.
+#[tracing::instrument(ret, level = "debug")]
 pub fn blank_line(input: &str) -> Res<&str, &str> {
     not(eof)(input)?;
     recognize(tuple((space0, alt((line_ending, eof)))))(input)
 }
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn trailing_whitespace(input: &str) -> Res<&str, &str> {
     alt((eof, recognize(tuple((line_ending, many0(blank_line))))))(input)
 }
 
 /// Check that we are at the start of a line
+#[tracing::instrument(ret, level = "debug")]
 pub fn start_of_line<'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)
@@ -103,6 +106,7 @@ pub fn start_of_line<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'
 /// Pull one non-whitespace character.
 ///
 /// This function only operates on spaces, tabs, carriage returns, and line feeds. It does not handle fancy unicode whitespace.
+#[tracing::instrument(ret, level = "debug")]
 pub fn non_whitespace_character(input: &str) -> Res<&str, char> {
     none_of(" \t\r\n")(input)
 }
@@ -116,6 +120,13 @@ pub fn exit_matcher_parser<'r, 's>(
     peek(|i| context.check_exit_matcher(i))(input)
 }
 
+#[tracing::instrument(ret, level = "debug")]
+pub fn always_fail<'r, 's>(_context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    Err(nom::Err::Error(CustomError::MyError(MyError(
+        "Always fail",
+    ))))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;