From f27965001d4ac7f52463e3e1b9ab30f817e2da65 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Wed, 12 Apr 2023 13:09:44 -0400
Subject: [PATCH] End plain lists when there are two blank lines.

---
 Makefile                 |  2 +-
 src/parser/element.rs    |  6 +++++
 src/parser/plain_list.rs | 55 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 6e63e0c..48749fd 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ clean:
 
 .PHONY: test
 test:
-> cargo test
+> cargo test --bin toy
 
 .PHONY: run
 run:
diff --git a/src/parser/element.rs b/src/parser/element.rs
index 9a2d189..4c6760c 100644
--- a/src/parser/element.rs
+++ b/src/parser/element.rs
@@ -38,6 +38,12 @@ impl<'s> Source<'s> for Paragraph<'s> {
     }
 }
 
+impl<'s> Source<'s> for PlainList<'s> {
+    fn get_source(&'s self) -> &'s str {
+        self.source
+    }
+}
+
 #[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);
diff --git a/src/parser/plain_list.rs b/src/parser/plain_list.rs
index cbdc295..0e881e7 100644
--- a/src/parser/plain_list.rs
+++ b/src/parser/plain_list.rs
@@ -11,6 +11,7 @@ use crate::parser::element::element;
 use crate::parser::parser_context::ChainBehavior;
 use crate::parser::parser_context::ContextElement;
 use crate::parser::parser_context::ExitMatcherNode;
+use crate::parser::util::blank_line;
 use crate::parser::util::exit_matcher_parser;
 use crate::parser::util::get_consumed;
 use crate::parser::util::start_of_line;
@@ -24,15 +25,20 @@ use nom::character::complete::space1;
 use nom::combinator::eof;
 use nom::combinator::recognize;
 use nom::combinator::verify;
+use nom::multi::many1;
 use nom::multi::many_till;
 use nom::sequence::tuple;
 
+#[tracing::instrument(ret, level = "debug")]
 pub fn plain_list<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, PlainList<'s>> {
-    // TODO: Are we handling 2 blank lines causing the end of all plain lists?
-    let (mut remaining, first_item) = plain_list_item(context, input)?;
+    let parser_context =
+        context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
+            exit_matcher: ChainBehavior::AndParent(Some(&plain_list_end)),
+        }));
+    let (mut remaining, first_item) = plain_list_item(&parser_context, input)?;
     let first_item_indentation = first_item.indentation;
-    let plain_list_item_matcher = parser_with_context!(plain_list_item)(context);
-    let exit_matcher = parser_with_context!(exit_matcher_parser)(context);
+    let plain_list_item_matcher = parser_with_context!(plain_list_item)(&parser_context);
+    let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
     let mut children = Vec::new();
     children.push(first_item);
     loop {
@@ -125,6 +131,15 @@ 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_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    let start_of_line_matcher = parser_with_context!(start_of_line)(context);
+    recognize(tuple((
+        start_of_line_matcher,
+        verify(many1(blank_line), |lines: &Vec<&str>| lines.len() >= 2),
+    )))(input)
+}
+
 #[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 current_item_indent_level: &usize =
@@ -138,7 +153,6 @@ fn plain_list_item_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<
             pli.indentation <= *current_item_indent_level
         })),
         recognize(line_indented_lte_matcher),
-        eof,
     ))(input)
 }
 
@@ -175,6 +189,7 @@ mod tests {
     use crate::parser::parser_context::ContextElement;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
+    use crate::parser::Source;
 
     use super::*;
 
@@ -249,4 +264,34 @@ mod tests {
         let result = plain_list_matcher(input);
         assert!(result.is_ok());
     }
+
+    #[test]
+    fn two_blank_lines_ends_list() {
+        // Plain lists with an asterisk bullet must be indented or else they would be a headline
+        let input = r#"1. foo
+2. bar
+   baz
+3. lorem
+
+
+   ipsum
+"#;
+        let initial_context: ContextTree<'_, '_> = ContextTree::new();
+        let document_context =
+            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
+        let plain_list_matcher = parser_with_context!(plain_list)(&document_context);
+        let (remaining, result) =
+            plain_list_matcher(input).expect("Should parse the plain list successfully.");
+        assert_eq!(remaining, "   ipsum\n");
+        assert_eq!(
+            result.get_source(),
+            r#"1. foo
+2. bar
+   baz
+3. lorem
+
+
+"#
+        );
+    }
 }