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, 29 insertions, 32 deletions

diff --git a/src/construct/gfm_table.rs b/src/construct/gfm_table.rs
index 27fbadf..63772c4 100644
--- a/src/construct/gfm_table.rs
+++ b/src/construct/gfm_table.rs
@@ -229,9 +229,10 @@ use crate::construct::partial_space_or_tab::{space_or_tab, space_or_tab_min_max}
 use crate::event::{Content, Event, Kind, Link, Name};
 use crate::resolve::Name as ResolveName;
 use crate::state::{Name as StateName, State};
+use crate::subtokenize::Subresult;
 use crate::tokenizer::Tokenizer;
 use crate::util::{constant::TAB_SIZE, skip::opt_back as skip_opt_back};
-use alloc::vec;
+use alloc::{string::String, vec};
 
 /// Start of a GFM table.
 ///
@@ -771,15 +772,13 @@ pub fn body_row_escape(tokenizer: &mut Tokenizer) -> State {
 }
 
 /// Resolve GFM table.
-pub fn resolve(tokenizer: &mut Tokenizer) {
+pub fn resolve(tokenizer: &mut Tokenizer) -> Result<Option<Subresult>, String> {
     let mut index = 0;
-    // let mut tables = vec![];
     let mut in_first_cell_awaiting_pipe = true;
     let mut in_row = false;
     let mut in_delimiter_row = false;
     let mut last_cell = (0, 0, 0, 0);
     let mut cell = (0, 0, 0, 0);
-
     let mut after_head_awaiting_first_body_row = false;
     let mut last_table_end = 0;
     let mut last_table_has_body = false;
@@ -800,17 +799,14 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
                 }
 
                 // Inject table start.
-                tokenizer.map.add(
-                    index,
-                    0,
-                    vec![Event {
-                        kind: Kind::Enter,
-                        name: Name::GfmTable,
-                        point: tokenizer.events[index].point.clone(),
-                        link: None,
-                    }],
-                );
-            } else if event.name == Name::GfmTableRow || event.name == Name::GfmTableDelimiterRow {
+                let enter = Event {
+                    kind: Kind::Enter,
+                    name: Name::GfmTable,
+                    point: tokenizer.events[index].point.clone(),
+                    link: None,
+                };
+                tokenizer.map.add(index, 0, vec![enter]);
+            } else if matches!(event.name, Name::GfmTableRow | Name::GfmTableDelimiterRow) {
                 in_delimiter_row = event.name == Name::GfmTableDelimiterRow;
                 in_row = true;
                 in_first_cell_awaiting_pipe = true;
@@ -821,23 +817,21 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
                 if after_head_awaiting_first_body_row {
                     after_head_awaiting_first_body_row = false;
                     last_table_has_body = true;
-                    tokenizer.map.add(
-                        index,
-                        0,
-                        vec![Event {
-                            kind: Kind::Enter,
-                            name: Name::GfmTableBody,
-                            point: tokenizer.events[index].point.clone(),
-                            link: None,
-                        }],
-                    );
+                    let enter = Event {
+                        kind: Kind::Enter,
+                        name: Name::GfmTableBody,
+                        point: tokenizer.events[index].point.clone(),
+                        link: None,
+                    };
+                    tokenizer.map.add(index, 0, vec![enter]);
                 }
             }
             // Cell data.
             else if in_row
-                && (event.name == Name::Data
-                    || event.name == Name::GfmTableDelimiterMarker
-                    || event.name == Name::GfmTableDelimiterFiller)
+                && matches!(
+                    event.name,
+                    Name::Data | Name::GfmTableDelimiterMarker | Name::GfmTableDelimiterFiller
+                )
             {
                 in_first_cell_awaiting_pipe = false;
 
@@ -868,7 +862,7 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
         } else if event.name == Name::GfmTableHead {
             after_head_awaiting_first_body_row = true;
             last_table_end = index;
-        } else if event.name == Name::GfmTableRow || event.name == Name::GfmTableDelimiterRow {
+        } else if matches!(event.name, Name::GfmTableRow | Name::GfmTableDelimiterRow) {
             in_row = false;
             last_table_end = index;
             if last_cell.1 != 0 {
@@ -878,9 +872,10 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
                 flush_cell(tokenizer, cell, in_delimiter_row, Some(index));
             }
         } else if in_row
-            && (event.name == Name::Data
-                || event.name == Name::GfmTableDelimiterMarker
-                || event.name == Name::GfmTableDelimiterFiller)
+            && (matches!(
+                event.name,
+                Name::Data | Name::GfmTableDelimiterMarker | Name::GfmTableDelimiterFiller
+            ))
         {
             cell.3 = index;
         }
@@ -891,6 +886,8 @@ pub fn resolve(tokenizer: &mut Tokenizer) {
     if last_table_end != 0 {
         flush_table_end(tokenizer, last_table_end, last_table_has_body);
     }
+
+    Ok(None)
 }
 
 /// Generate a cell.