From cf6c4bc122c7acae81356f062e2a4365822c4b5c Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Fri, 21 Apr 2023 17:32:53 -0400
Subject: [PATCH] Write a parser specifically for comment lesser blocks.

---
 src/parser/lesser_block.rs   | 61 ++++++++++++++++++++++++++++++++++++
 src/parser/lesser_element.rs |  8 +++++
 2 files changed, 69 insertions(+)

diff --git a/src/parser/lesser_block.rs b/src/parser/lesser_block.rs
index fdef894..509889a 100644
--- a/src/parser/lesser_block.rs
+++ b/src/parser/lesser_block.rs
@@ -6,6 +6,7 @@ use nom::character::complete::space0;
 use nom::character::complete::space1;
 use nom::combinator::consumed;
 use nom::combinator::eof;
+use nom::combinator::map;
 use nom::combinator::opt;
 use nom::combinator::verify;
 use nom::multi::many_till;
@@ -15,10 +16,12 @@ use super::error::Res;
 use super::Context;
 use crate::parser::exiting::ExitClass;
 use crate::parser::lesser_element::LesserBlock;
+use crate::parser::lesser_element::LesserBlockComment;
 use crate::parser::object_parser::standard_set_object;
 use crate::parser::parser_context::ContextElement;
 use crate::parser::parser_context::ExitMatcherNode;
 use crate::parser::parser_with_context::parser_with_context;
+use crate::parser::plain_text::plain_text;
 use crate::parser::util::blank_line;
 use crate::parser::util::exit_matcher_parser;
 use crate::parser::util::get_consumed;
@@ -83,6 +86,47 @@ pub fn lesser_block<'r, 's>(
     ))
 }
 
+#[tracing::instrument(ret, level = "debug")]
+pub fn lesser_block_comment<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, LesserBlockComment<'s>> {
+    let (remaining, name) = lesser_block_begin("comment")(context, input)?;
+    let (remaining, parameters) = opt(tuple((space1, data)))(remaining)?;
+    let (remaining, _nl) = line_ending(remaining)?;
+    let lesser_block_end_specialized = lesser_block_end("comment");
+    let parser_context = context
+        .with_additional_node(ContextElement::ConsumeTrailingWhitespace(true))
+        .with_additional_node(ContextElement::Context("lesser block"))
+        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
+            class: ExitClass::Beta,
+            exit_matcher: &lesser_block_end_specialized,
+        }));
+    let parameters = match parameters {
+        Some((_ws, parameters)) => Some(parameters),
+        None => None,
+    };
+
+    let (remaining, contents) = map(parser_with_context!(plain_text)(&parser_context), |obj| {
+        obj.source
+    })(remaining)?;
+    let (remaining, _end) = lesser_block_end_specialized(&parser_context, remaining)?;
+
+    let (remaining, _trailing_ws) =
+        maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((
+        remaining,
+        LesserBlockComment {
+            source,
+            name,
+            data: parameters,
+            contents,
+        },
+    ))
+}
+
 #[tracing::instrument(ret, level = "debug")]
 fn name<'s>(input: &'s str) -> Res<&'s str, &'s str> {
     is_not(" \t\r\n")(input)
@@ -109,3 +153,20 @@ fn lesser_block_end(
         Ok((remaining, source))
     }
 }
+
+fn lesser_block_begin(
+    current_name: &str,
+) -> impl for<'r, 's> Fn(Context<'r, 's>, &'s str) -> Res<&'s str, &'s str> {
+    let current_name_lower = current_name.to_lowercase();
+    move |context: Context, input: &str| {
+        start_of_line(context, input)?;
+        let (remaining, _leading_whitespace) = space0(input)?;
+        let (remaining, (_begin, name)) = tuple((
+            tag_no_case("#+begin_"),
+            verify(name, |name: &str| {
+                name.to_lowercase().as_str() == current_name_lower
+            }),
+        ))(remaining)?;
+        Ok((remaining, name))
+    }
+}
diff --git a/src/parser/lesser_element.rs b/src/parser/lesser_element.rs
index fa7905a..7da000b 100644
--- a/src/parser/lesser_element.rs
+++ b/src/parser/lesser_element.rs
@@ -27,6 +27,14 @@ pub struct LesserBlock<'s> {
     pub children: Vec<Object<'s>>,
 }
 
+#[derive(Debug)]
+pub struct LesserBlockComment<'s> {
+    pub source: &'s str,
+    pub name: &'s str,
+    pub data: Option<&'s str>,
+    pub contents: &'s str,
+}
+
 impl<'s> Paragraph<'s> {
     pub fn of_text(input: &'s str) -> Self {
         let mut objects = Vec::with_capacity(1);