A first stab at lesser blocks.

src/parser/greater_block.rs

@@ -37,7 +37,6 @@ pub fn greater_block<'r, 's>(
     // TODO: Do I need to differentiate between different greater block types.
     start_of_line(context, input)?;
     let (remaining, _leading_whitespace) = space0(input)?;
-    // TODO: Not handling indentation before start of block
     let (remaining, (_begin, name)) = tuple((
         tag_no_case("#+begin_"),
         verify(name, |name: &str| match name.to_lowercase().as_str() {

src/parser/lesser_block.rs

@@ -1,11 +1,107 @@
+use nom::branch::alt;
+use nom::bytes::complete::is_not;
+use nom::bytes::complete::tag_no_case;
+use nom::character::complete::line_ending;
+use nom::character::complete::space0;
+use nom::character::complete::space1;
+use nom::combinator::consumed;
+use nom::combinator::eof;
+use nom::combinator::opt;
+use nom::combinator::verify;
+use nom::multi::many_till;
+use nom::sequence::tuple;
+
 use super::error::Res;
 use super::Context;
+use crate::parser::exiting::ExitClass;
 use crate::parser::lesser_element::LesserBlock;
+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::util::blank_line;
+use crate::parser::util::exit_matcher_parser;
+use crate::parser::util::get_consumed;
+use crate::parser::util::maybe_consume_trailing_whitespace_if_not_exiting;
+use crate::parser::util::start_of_line;
 
 #[tracing::instrument(ret, level = "debug")]
 pub fn lesser_block<'r, 's>(
     context: Context<'r, 's>,
     input: &'s str,
 ) -> Res<&'s str, LesserBlock<'s>> {
-    todo!()
+    start_of_line(context, input)?;
+    let (remaining, _leading_whitespace) = space0(input)?;
+    let (remaining, (_begin, name)) = tuple((
+        tag_no_case("#+begin_"),
+        verify(name, |name: &str| match name.to_lowercase().as_str() {
+            "comment" | "example" | "export" | "src" | "verse" => true,
+            _ => false,
+        }),
+    ))(remaining)?;
+
+    let (remaining, parameters) = opt(tuple((space1, data)))(remaining)?;
+    let (remaining, _nl) = line_ending(remaining)?;
+    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,
+        }));
+    let parameters = match parameters {
+        Some((_ws, parameters)) => Some(parameters),
+        None => None,
+    };
+
+    let object_matcher = parser_with_context!(standard_set_object)(&parser_context);
+    let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
+    // Check for a completely empty block
+    let (remaining, children) = match consumed(many_till(blank_line, exit_matcher))(remaining) {
+        Ok((remaining, (whitespace, (_children, _exit_contents)))) => todo!(),
+        Err(_) => {
+            let (remaining, (children, _exit_contents)) =
+                many_till(object_matcher, exit_matcher)(remaining)?;
+            (remaining, children)
+        }
+    };
+    let (remaining, _end) = lesser_block_end(&parser_context, remaining)?;
+
+    let (remaining, _trailing_ws) =
+        maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((
+        remaining,
+        LesserBlock {
+            source,
+            name,
+            data: parameters,
+            children,
+        },
+    ))
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn name<'s>(input: &'s str) -> Res<&'s str, &'s str> {
+    is_not(" \t\r\n")(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn data<'s>(input: &'s str) -> Res<&'s str, &'s str> {
+    is_not("\r\n")(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn lesser_block_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    start_of_line(context, input)?;
+    let current_name = "comment"; // TODO
+    let (remaining, _leading_whitespace) = space0(input)?;
+    let (remaining, (_begin, _name, _ws)) = tuple((
+        tag_no_case("#+end_"),
+        tag_no_case(current_name),
+        alt((eof, line_ending)),
+    ))(remaining)?;
+    let source = get_consumed(input, remaining);
+    Ok((remaining, source))
 }