From b557b9ca5dada44c7057d11f738437e3ecd82298 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Wed, 19 Apr 2023 18:37:39 -0400
Subject: [PATCH] Accounting for the blank lines at the head of documents and
 comments plus property drawer at the head of the zeroth section.

---
 Cargo.toml                                    |  1 -
 .../property_drawer/zeroth_section.org        | 17 ++++++++
 src/parser/document.rs                        | 41 ++++++++++++++++++-
 toy_language.txt                              |  9 ++--
 4 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 7f42a243..9e11b28b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,6 @@ name = "toy"
 version = "0.1.0"
 edition = "2021"
 license = "0BSD"
-default-run = "toy"
 
 [lib]
 name = "organic"
diff --git a/org_mode_samples/property_drawer/zeroth_section.org b/org_mode_samples/property_drawer/zeroth_section.org
index ccdae6fa..25380541 100644
--- a/org_mode_samples/property_drawer/zeroth_section.org
+++ b/org_mode_samples/property_drawer/zeroth_section.org
@@ -6,3 +6,20 @@
 :PROPERTIES:
 :FOO:    bar
 :END:
+
+
+
+* Spaces turn property drawers into regular drawers
+
+:PROPERTIES:
+:FOO:    bar
+:END:
+* Comments turn property drawers into regular drawers
+# Comment
+:PROPERTIES:
+:FOO:    bar
+:END:
+* Baseline
+:PROPERTIES:
+:FOO:    bar
+:END:
diff --git a/src/parser/document.rs b/src/parser/document.rs
index f2e4308b..309e2aec 100644
--- a/src/parser/document.rs
+++ b/src/parser/document.rs
@@ -1,3 +1,4 @@
+use crate::parser::property_drawer::property_drawer;
 use nom::branch::alt;
 use nom::bytes::complete::tag;
 use nom::character::complete::line_ending;
@@ -13,12 +14,14 @@ use nom::multi::many1_count;
 use nom::multi::many_till;
 use nom::sequence::tuple;
 
+use crate::parser::comment::comment;
 use crate::parser::element::element;
 use crate::parser::exiting::ExitClass;
 use crate::parser::object::standard_set_object;
 use crate::parser::parser_context::ContextElement;
 use crate::parser::parser_context::ContextTree;
 use crate::parser::parser_context::ExitMatcherNode;
+use crate::parser::util::blank_line;
 use crate::parser::util::maybe_consume_trailing_whitespace_if_not_exiting;
 
 use super::element::Element;
@@ -92,9 +95,10 @@ pub fn document(input: &str) -> Res<&str, Document> {
     let initial_context: ContextTree<'_, '_> = ContextTree::new();
     let document_context =
         initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-    let section_matcher = parser_with_context!(section)(&document_context);
+    let zeroth_section_matcher = parser_with_context!(zeroth_section)(&document_context);
     let heading_matcher = parser_with_context!(heading)(&document_context);
-    let (remaining, zeroth_section) = opt(section_matcher)(input)?;
+    let (remaining, _blank_lines) = many0(blank_line)(input)?;
+    let (remaining, zeroth_section) = opt(zeroth_section_matcher)(remaining)?;
     let (remaining, children) = many0(heading_matcher)(remaining)?;
     let source = get_consumed(input, remaining);
     Ok((
@@ -107,6 +111,39 @@ pub fn document(input: &str) -> Res<&str, Document> {
     ))
 }
 
+#[tracing::instrument(ret, level = "debug")]
+fn zeroth_section<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Section<'s>> {
+    // TODO: The zeroth section is specialized so it probably needs its own parser
+    let parser_context = context
+        .with_additional_node(ContextElement::ConsumeTrailingWhitespace(true))
+        .with_additional_node(ContextElement::Context("section"))
+        .with_additional_node(ContextElement::ExitMatcherNode(ExitMatcherNode {
+            class: ExitClass::Document,
+            exit_matcher: &section_end,
+        }));
+    let element_matcher = parser_with_context!(element)(&parser_context);
+    let exit_matcher = parser_with_context!(exit_matcher_parser)(&parser_context);
+
+    let (remaining, (comment_element, property_drawer_element)) = tuple((
+        opt(parser_with_context!(comment)(&parser_context)),
+        opt(parser_with_context!(property_drawer)(&parser_context)),
+    ))(input)?;
+
+    let (remaining, (mut children, _exit_contents)) = verify(
+        many_till(element_matcher, exit_matcher),
+        |(children, _exit_contents)| !children.is_empty(),
+    )(remaining)?;
+    property_drawer_element.map(Element::PropertyDrawer).map(|ele| children.insert(0, ele));
+    comment_element.map(Element::Comment).map(|ele| children.insert(0, ele));
+    // children.insert(0, item)
+
+    let (remaining, _trailing_ws) =
+        maybe_consume_trailing_whitespace_if_not_exiting(context, remaining)?;
+
+    let source = get_consumed(input, remaining);
+    Ok((remaining, Section { source, children }))
+}
+
 #[tracing::instrument(ret, level = "debug")]
 fn section<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Section<'s>> {
     // TODO: The zeroth section is specialized so it probably needs its own parser
diff --git a/toy_language.txt b/toy_language.txt
index 574a2f2e..ccdae6fa 100644
--- a/toy_language.txt
+++ b/toy_language.txt
@@ -1,5 +1,8 @@
-foo
-:drawername:
 
 
-:end:
+
+
+# Blank lines and comments can come before property drawers in the zeroth section
+:PROPERTIES:
+:FOO:    bar
+:END: