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, 3 insertions, 2 deletions

diff --git a/src/construct/document.rs b/src/construct/document.rs
index 45a961d..82f2ebd 100644
--- a/src/construct/document.rs
+++ b/src/construct/document.rs
@@ -413,7 +413,7 @@ pub fn flow_end(tokenizer: &mut Tokenizer) -> State {
     while !document_lazy_continuation_current && stack_index > 0 {
         stack_index -= 1;
         let name = &child.stack[stack_index];
-        if name == &Name::Paragraph || name == &Name::Definition || name == &Name::GfmTableHead {
+        if name == &Name::Content || name == &Name::GfmTableHead {
             document_lazy_continuation_current = true;
         }
     }
@@ -423,7 +423,7 @@ pub fn flow_end(tokenizer: &mut Tokenizer) -> State {
     if !document_lazy_continuation_current && !child.events.is_empty() {
         let before = skip::opt_back(&child.events, child.events.len() - 1, &[Name::LineEnding]);
         let name = &child.events[before].name;
-        if name == &Name::Paragraph {
+        if name == &Name::Content {
             document_lazy_continuation_current = true;
         }
     }
@@ -582,6 +582,7 @@ fn resolve(tokenizer: &mut Tokenizer) {
         &tokenizer.events,
         flow_index,
         &mut child.events,
+        (0, 0),
     );
 
     // Replace the flow data with actual events.