From 6e6ec56d1fce19f3a5ec5bee5594a2aa3c4d9e6f Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Mon, 3 Apr 2023 18:33:07 -0400
Subject: [PATCH] Basic implementation of greater block parser.

---
 src/parser/element.rs        |  7 ++-
 src/parser/greater_block.rs  | 88 ++++++++++++++++++++++++++++++++++++
 src/parser/parser_context.rs |  5 +-
 3 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/src/parser/element.rs b/src/parser/element.rs
index 2568f34..49f543d 100644
--- a/src/parser/element.rs
+++ b/src/parser/element.rs
@@ -1,4 +1,5 @@
 use super::error::Res;
+use super::greater_block::greater_block;
 use super::greater_element::GreaterBlock;
 use super::greater_element::PlainList;
 use super::lesser_element::Paragraph;
@@ -48,5 +49,9 @@ pub fn non_paragraph_element<'r, 's>(
     input: &'s str,
 ) -> Res<&'s str, Element<'s>> {
     let plain_list_matcher = parser_with_context!(plain_list)(context);
-    map(plain_list_matcher, Element::PlainList)(input)
+    let greater_block_matcher = parser_with_context!(greater_block)(context);
+    alt((
+        map(plain_list_matcher, Element::PlainList),
+        map(greater_block_matcher, Element::GreaterBlock),
+    ))(input)
 }
diff --git a/src/parser/greater_block.rs b/src/parser/greater_block.rs
index 8b13789..1401007 100644
--- a/src/parser/greater_block.rs
+++ b/src/parser/greater_block.rs
@@ -1 +1,89 @@
+use super::error::Res;
+use super::Context;
+use crate::parser::element::element;
+use crate::parser::error::CustomError;
+use crate::parser::error::MyError;
+use crate::parser::greater_element::GreaterBlock;
+use crate::parser::parser_context::ChainBehavior;
+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::exit_matcher_parser;
+use crate::parser::util::get_consumed;
+use crate::parser::util::start_of_line;
+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::space1;
+use nom::combinator::eof;
+use nom::combinator::opt;
+use nom::multi::many_till;
+use nom::sequence::tuple;
 
+pub fn greater_block<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, GreaterBlock<'s>> {
+    let (remaining, (_begin, name)) = tuple((tag_no_case("#+begin_"), name))(input)?;
+    let (remaining, parameters) = opt(tuple((space1, parameters)))(remaining)?;
+    let (remaining, _nl) = line_ending(remaining)?;
+    let parser_context = context
+        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
+            exit_matcher: ChainBehavior::IgnoreParent(Some(&greater_block_end)),
+        }))
+        .with_additional_node(ContextElement::GreaterBlock(name));
+
+    let element_matcher = parser_with_context!(element)(&parser_context);
+    let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
+    let (remaining, (children, _exit_contents)) =
+        many_till(element_matcher, exit_matcher)(remaining)?;
+    let (remaining, _end) = greater_block_end(&parser_context, remaining)?;
+    let parameters = match parameters {
+        Some((_ws, parameters)) => Some(parameters),
+        None => None,
+    };
+    let source = get_consumed(input, remaining);
+    Ok((
+        remaining,
+        GreaterBlock {
+            source,
+            name,
+            parameters,
+            children,
+        },
+    ))
+}
+
+fn name<'s>(input: &'s str) -> Res<&'s str, &'s str> {
+    is_not(" \t\r\n")(input)
+}
+
+fn parameters<'s>(input: &'s str) -> Res<&'s str, &'s str> {
+    is_not("\r\n")(input)
+}
+
+#[tracing::instrument(ret, level = "debug")]
+fn greater_block_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, &'s str> {
+    start_of_line(context, input)?;
+    let current_name: &str = get_context_greater_block_name(context).ok_or(nom::Err::Error(
+        CustomError::MyError(MyError("Not inside a greater block")),
+    ))?;
+    let (remaining, (_begin, _name, _ws)) = tuple((
+        tag_no_case("#+end_"),
+        tag_no_case(current_name),
+        alt((eof, line_ending)),
+    ))(input)?;
+    let source = get_consumed(input, remaining);
+    Ok((remaining, source))
+}
+
+fn get_context_greater_block_name<'r, 's>(context: Context<'r, 's>) -> Option<&'s str> {
+    for thing in context.iter() {
+        match thing.get_data() {
+            ContextElement::GreaterBlock(name) => return Some(name),
+            _ => {}
+        };
+    }
+    None
+}
diff --git a/src/parser/parser_context.rs b/src/parser/parser_context.rs
index 5070d03..5bbb8a7 100644
--- a/src/parser/parser_context.rs
+++ b/src/parser/parser_context.rs
@@ -128,6 +128,9 @@ pub enum ContextElement<'r, 's> {
 
     /// Stores the indentation level of the current list item
     ListItem(usize),
+
+    /// Stores the name of the greater block
+    GreaterBlock(&'s str),
 }
 
 #[derive(Debug)]
@@ -138,8 +141,6 @@ pub struct ExitMatcherNode<'r> {
 #[derive(Clone)]
 pub enum ChainBehavior<'r> {
     AndParent(Option<&'r Matcher>),
-
-    #[allow(dead_code)] // Will be used when inside code/quote blocks
     IgnoreParent(Option<&'r Matcher>),
 }