From bdba495f690869a8dbcaf953d48c70201b41d033 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Mon, 4 Sep 2023 22:39:24 -0400
Subject: [PATCH] Add a parser for the todo keyword's value.

---
 src/parser/in_buffer_settings.rs | 16 +++++-
 src/parser/keyword_todo.rs       | 90 ++++++++++++++++++++++++++++++++
 src/parser/mod.rs                |  1 +
 3 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 src/parser/keyword_todo.rs

diff --git a/src/parser/in_buffer_settings.rs b/src/parser/in_buffer_settings.rs
index f21dc1a..3c533ac 100644
--- a/src/parser/in_buffer_settings.rs
+++ b/src/parser/in_buffer_settings.rs
@@ -25,5 +25,19 @@ pub fn scan_for_in_buffer_settings<'s>(
 
 #[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
 fn in_buffer_settings_key<'s>(input: OrgSource<'s>) -> Res<OrgSource<'s>, OrgSource<'s>> {
-    alt((tag_no_case("todo"), tag_no_case("setupfile")))(input)
+    alt((
+        tag_no_case("archive"),
+        tag_no_case("category"),
+        tag_no_case("columns"),
+        tag_no_case("filetags"),
+        tag_no_case("link"),
+        tag_no_case("priorities"),
+        tag_no_case("property"),
+        tag_no_case("seq_todo"),
+        tag_no_case("setupfile"),
+        tag_no_case("startup"),
+        tag_no_case("tags"),
+        tag_no_case("todo"),
+        tag_no_case("typ_todo"),
+    ))(input)
 }
diff --git a/src/parser/keyword_todo.rs b/src/parser/keyword_todo.rs
new file mode 100644
index 0000000..44facbb
--- /dev/null
+++ b/src/parser/keyword_todo.rs
@@ -0,0 +1,90 @@
+use nom::branch::alt;
+use nom::bytes::complete::tag;
+use nom::bytes::complete::take_till;
+use nom::character::complete::line_ending;
+use nom::character::complete::space0;
+use nom::character::complete::space1;
+use nom::combinator::eof;
+use nom::combinator::opt;
+use nom::combinator::verify;
+use nom::multi::separated_list0;
+use nom::sequence::tuple;
+
+use crate::error::Res;
+
+/// Parses the text in the value of a #+TODO keyword.
+///
+/// Example input: "foo bar baz | lorem ipsum"
+pub fn keyword_todo<'s>(input: &'s str) -> Res<&'s str, (Vec<&'s str>, Vec<&'s str>)> {
+    let (remaining, mut before_pipe_words) = separated_list0(space1, keyword_word)(input)?;
+    let (remaining, after_pipe_words) = opt(tuple((
+        tuple((space0, tag("|"), space0)),
+        separated_list0(space1, keyword_word),
+    )))(remaining)?;
+    let (remaining, _eol) = alt((line_ending, eof))(remaining)?;
+    if let Some((_pipe, after_pipe_words)) = after_pipe_words {
+        Ok((remaining, (before_pipe_words, after_pipe_words)))
+    } else if !before_pipe_words.is_empty() {
+        // If there was no pipe, then the last word becomes a completion state instead.
+        let mut after_pipe_words = Vec::with_capacity(1);
+        after_pipe_words.push(
+            before_pipe_words
+                .pop()
+                .expect("If-statement proves this is Some."),
+        );
+        Ok((remaining, (before_pipe_words, after_pipe_words)))
+    } else {
+        // No words founds
+        Ok((remaining, (Vec::new(), Vec::new())))
+    }
+}
+
+fn keyword_word<'s>(input: &'s str) -> Res<&'s str, &'s str> {
+    verify(take_till(|c| " \t\r\n|".contains(c)), |result: &str| {
+        !result.is_empty()
+    })(input)
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn before_and_after() -> Result<(), Box<dyn std::error::Error>> {
+        let input = "foo bar baz | lorem ipsum";
+        let (remaining, (before_pipe_words, after_pipe_words)) = keyword_todo(input)?;
+        assert_eq!(remaining, "");
+        assert_eq!(before_pipe_words, vec!["foo", "bar", "baz"]);
+        assert_eq!(after_pipe_words, vec!["lorem", "ipsum"]);
+        Ok(())
+    }
+
+    #[test]
+    fn no_pipe() -> Result<(), Box<dyn std::error::Error>> {
+        let input = "foo bar baz";
+        let (remaining, (before_pipe_words, after_pipe_words)) = keyword_todo(input)?;
+        assert_eq!(remaining, "");
+        assert_eq!(before_pipe_words, vec!["foo", "bar"]);
+        assert_eq!(after_pipe_words, vec!["baz"]);
+        Ok(())
+    }
+
+    #[test]
+    fn early_pipe() -> Result<(), Box<dyn std::error::Error>> {
+        let input = "| foo bar baz";
+        let (remaining, (before_pipe_words, after_pipe_words)) = keyword_todo(input)?;
+        assert_eq!(remaining, "");
+        assert_eq!(before_pipe_words, Vec::<&str>::new());
+        assert_eq!(after_pipe_words, vec!["foo", "bar", "baz"]);
+        Ok(())
+    }
+
+    #[test]
+    fn late_pipe() -> Result<(), Box<dyn std::error::Error>> {
+        let input = "foo bar baz |";
+        let (remaining, (before_pipe_words, after_pipe_words)) = keyword_todo(input)?;
+        assert_eq!(remaining, "");
+        assert_eq!(before_pipe_words, vec!["foo", "bar", "baz"]);
+        assert_eq!(after_pipe_words, Vec::<&str>::new());
+        Ok(())
+    }
+}
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index 72a350c..0b95974 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -19,6 +19,7 @@ mod in_buffer_settings;
 mod inline_babel_call;
 mod inline_source_block;
 mod keyword;
+mod keyword_todo;
 mod latex_environment;
 mod latex_fragment;
 mod lesser_block;