Fix to prefer flow over definitions, setext headings

An undocumented part of CommonMark is how to deal with things in definition
labels or definition titles (which both can span multiple lines).
Can flow (or containers?) interrupt them?
They can according to the `cmark` reference parser, so this was implemented here.

This adds a new `Content` content type, which houses zero or more definitions,
and then zero-or-one paragraphs.
Content can be followed by a setext heading underline, which either turns
into a setext heading when the content ends in a paragraph, or turns into
the start of the following paragraph when it is followed by content that
starts with a paragraph, or turns into a stray paragraph.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/construct/text.rs b/src/construct/text.rs
index 34ea071..2648531 100644
--- a/src/construct/text.rs
+++ b/src/construct/text.rs
@@ -28,7 +28,9 @@ use crate::construct::gfm_autolink_literal::resolve as resolve_gfm_autolink_lite
 use crate::construct::partial_whitespace::resolve_whitespace;
 use crate::resolve::Name as ResolveName;
 use crate::state::{Name as StateName, State};
+use crate::subtokenize::Subresult;
 use crate::tokenizer::Tokenizer;
+use alloc::string::String;
 
 /// Characters that can start something in text.
 const MARKERS: [u8; 16] = [
@@ -242,7 +244,7 @@ pub fn before_data(tokenizer: &mut Tokenizer) -> State {
 }
 
 /// Resolve whitespace.
-pub fn resolve(tokenizer: &mut Tokenizer) {
+pub fn resolve(tokenizer: &mut Tokenizer) -> Result<Option<Subresult>, String> {
     resolve_whitespace(
         tokenizer,
         tokenizer.parse_state.options.constructs.hard_break_trailing,
@@ -257,4 +259,6 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
     {
         resolve_gfm_autolink_literal(tokenizer);
     }
+
+    Ok(None)
 }