From 2d4e54845b6e9b035161f329d9860f95dc53f258 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Fri, 25 Aug 2023 06:13:29 -0400
Subject: [PATCH] Add support for parsing tags in headlines.

---
 .../greater_element/dynamic_block/simple.org  |  6 ++--
 src/compare/diff.rs                           |  2 ++
 src/parser/document.rs                        | 30 ++++++++++++++++---
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/org_mode_samples/greater_element/dynamic_block/simple.org b/org_mode_samples/greater_element/dynamic_block/simple.org
index a21ce8a..1034c5e 100644
--- a/org_mode_samples/greater_element/dynamic_block/simple.org
+++ b/org_mode_samples/greater_element/dynamic_block/simple.org
@@ -14,10 +14,12 @@
 |-------+------+----------+------------------------------|
 | Baz   |      | B        | :thisisatag:                 |
 | Lorem |      | B        | :thisshouldinheritfromabove: |
-| Ipsum |      | B        |                              |
+| Ipsum |      | B        | :multiple:tags:              |
 #+END:
 * Foo
 * TODO Bar
 * Baz :thisisatag:
 ** Lorem :thisshouldinheritfromabove:
-*** Ipsum
+*** Ipsum                                                   :multiple:tags:
+* Dolar ::
+* cat :dog: bat
diff --git a/src/compare/diff.rs b/src/compare/diff.rs
index 4b18716..c68db81 100644
--- a/src/compare/diff.rs
+++ b/src/compare/diff.rs
@@ -348,6 +348,8 @@ fn compare_heading<'s>(
         child_status.push(compare_object(source, emacs_child, rust_child)?);
     }
 
+    // TODO: Compare tags, todo-keyword, level, priority
+
     for (emacs_child, rust_child) in children.iter().skip(2).zip(rust.children.iter()) {
         match rust_child {
             DocumentElement::Heading(rust_heading) => {
diff --git a/src/parser/document.rs b/src/parser/document.rs
index 957fff2..dd4e117 100644
--- a/src/parser/document.rs
+++ b/src/parser/document.rs
@@ -1,6 +1,8 @@
 use nom::branch::alt;
 use nom::bytes::complete::tag;
+use nom::character::complete::anychar;
 use nom::character::complete::line_ending;
+use nom::character::complete::space0;
 use nom::character::complete::space1;
 use nom::combinator::eof;
 use nom::combinator::map;
@@ -12,6 +14,7 @@ use nom::multi::many0;
 use nom::multi::many1;
 use nom::multi::many1_count;
 use nom::multi::many_till;
+use nom::multi::separated_list1;
 use nom::sequence::tuple;
 
 use super::element::Element;
@@ -297,26 +300,45 @@ fn headline<'r, 's>(
     let parser_context =
         context.with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
             class: ExitClass::Document,
-            exit_matcher: &headline_end,
+            exit_matcher: &headline_title_end,
         }));
     let standard_set_object_matcher = parser_with_context!(standard_set_object)(&parser_context);
 
-    let (remaining, (_sol, star_count, ws, title, _line_ending)) = tuple((
+    let (remaining, (_sol, star_count, ws, title, maybe_tags, _ws, _line_ending)) = tuple((
         start_of_line,
         many1_count(tag("*")),
         space1,
         many1(standard_set_object_matcher),
+        opt(tuple((space0, tags))),
+        space0,
         alt((line_ending, eof)),
     ))(input)?;
     Ok((remaining, (star_count, ws, title)))
 }
 
 #[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
-fn headline_end<'r, 's>(
+fn headline_title_end<'r, 's>(
     _context: Context<'r, 's>,
     input: OrgSource<'s>,
 ) -> Res<OrgSource<'s>, OrgSource<'s>> {
-    line_ending(input)
+    recognize(tuple((
+        opt(tuple((space0, tags, space0))),
+        alt((line_ending, eof)),
+    )))(input)
+}
+
+#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
+fn tags<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, Vec<OrgSource<'s>>> {
+    let (remaining, (_open, tags, _close)) =
+        tuple((tag(":"), separated_list1(tag(":"), single_tag), tag(":")))(input)?;
+    Ok((remaining, tags))
+}
+
+#[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
+fn single_tag<'r, 's>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
+    recognize(many1(verify(anychar, |c| {
+        c.is_alphanumeric() || "_@#%".contains(*c)
+    })))(input)
 }
 
 impl<'s> Document<'s> {