From fbd8811c868f892342d48f69c703894839abd464 Mon Sep 17 00:00:00 2001
From: Noah Hellman <noah@hllmn.net>
Date: Sat, 4 Feb 2023 10:20:05 +0100
Subject: [PATCH] block: parse description list

---
 src/block.rs | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/lib.rs   | 18 +++++++-------
 2 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/src/block.rs b/src/block.rs
index 616614c..3164932 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -60,6 +60,9 @@ pub enum Leaf {
     /// Each inline is a line.
     Heading { has_section: bool },
 
+    /// Span is empty.
+    DescriptionTerm,
+
     /// Span is '|'.
     /// Has zero or one inline for the cell contents.
     TableCell(Alignment),
@@ -354,12 +357,39 @@ impl<'s> TreeParser<'s> {
             }
         }
 
-        self.tree.enter(Node::Container(c), span);
+        let dt = if let ListItem(Description) = c {
+            let dt = self
+                .tree
+                .enter(Node::Leaf(DescriptionTerm), span.empty_after());
+            self.tree.exit();
+            Some(dt)
+        } else {
+            None
+        };
+
+        let node = self.tree.enter(Node::Container(c), span);
         let mut l = 0;
         while l < lines.len() {
             l += self.parse_block(&mut lines[l..], false);
         }
 
+        if let Some(node_dt) = dt {
+            let node_child = if let Some(node_child) = self.tree.children(node).next() {
+                if let tree::Element::Container(Node::Leaf(l @ Paragraph)) = node_child.elem {
+                    *l = DescriptionTerm;
+                    Some(node_child.index)
+                } else {
+                    None
+                }
+            } else {
+                None
+            };
+            if let Some(node_child) = node_child {
+                self.tree.swap_prev(node_child);
+                self.tree.remove(node_dt);
+            }
+        }
+
         if let Some(OpenList { depth, .. }) = self.open_lists.last() {
             assert!(usize::from(*depth) <= self.tree.depth());
             if self.tree.depth() == (*depth).into() {
@@ -1684,6 +1714,40 @@ mod test {
         );
     }
 
+    #[test]
+    fn parse_description_list() {
+        test_parse!(
+            concat!(
+                ": term\n",         //
+                "\n",               //
+                "   description\n", //
+            ),
+            (
+                Enter(Container(List {
+                    ty: Description,
+                    tight: false
+                })),
+                ":"
+            ),
+            (Enter(Leaf(DescriptionTerm)), ""),
+            (Inline, "term"),
+            (Exit(Leaf(DescriptionTerm)), ""),
+            (Enter(Container(ListItem(Description))), ":"),
+            (Atom(Blankline), "\n"),
+            (Enter(Leaf(Paragraph)), ""),
+            (Inline, "description"),
+            (Exit(Leaf(Paragraph)), ""),
+            (Exit(Container(ListItem(Description))), ":"),
+            (
+                Exit(Container(List {
+                    ty: Description,
+                    tight: false
+                })),
+                ":"
+            ),
+        );
+    }
+
     #[test]
     fn parse_table() {
         test_parse!(
diff --git a/src/lib.rs b/src/lib.rs
index ed46d78..8553d4b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -721,6 +721,7 @@ impl<'s> Parser<'s> {
                                         .to_string()
                                         .into(),
                                 },
+                                block::Leaf::DescriptionTerm => Container::DescriptionTerm,
                                 block::Leaf::CodeBlock => {
                                     if let Some(format) = content.strip_prefix('=') {
                                         Container::RawBlock { format }
@@ -771,16 +772,13 @@ impl<'s> Parser<'s> {
                                     Container::List { kind, tight }
                                 }
                             }
-                            block::Container::ListItem(ty) => {
-                                if matches!(ty, block::ListType::Task) {
-                                    let marker = ev.span.of(self.src);
-                                    Container::TaskListItem {
-                                        checked: marker.as_bytes()[3] != b' ',
-                                    }
-                                } else {
-                                    Container::ListItem
-                                }
-                            }
+                            block::Container::ListItem(ty) => match ty {
+                                block::ListType::Task => Container::TaskListItem {
+                                    checked: content.as_bytes()[3] != b' ',
+                                },
+                                block::ListType::Description => Container::DescriptionDetails,
+                                _ => Container::ListItem,
+                            },
                             block::Container::Table => Container::Table,
                             block::Container::TableRow { head } => {
                                 if enter {