fix: fix EPUB transformation of HTML elements spanning multiple blocks

Cargo.toml

@@ -18,6 +18,7 @@ aho-corasick = "1.0.0"
 anyhow = "1.0.47"
 env_logger = "0.11.0"
 genawaiter = { version = "0.99.1", default-features = false }
+html5gum = "0.5.7"
 log = "0.4.0"
 mdbook = { version = "0.4.35", default-features = false }
 normpath = "1.0.0"

src/lib.rs

@@ -1216,6 +1216,63 @@ fn main() {}
         "###);
     }
 
+    #[test]
+    fn matched_html_tags() {
+        let output = MDBook::init()
+            .config(Config::pandoc())
+            .chapter(Chapter::new(
+                "Chapter",
+                "
+<details>
+<summary>
+
+## Heading
+
+text
+
+</summary>
+<p>
+
+more **markdown**
+
+</p>
+</details>
+
+outside divs
+            ",
+                "chapter.md",
+            ))
+            .build();
+        insta::assert_snapshot!(output, @r###"
+        ├─ log output
+        │  INFO mdbook::book: Running the pandoc backend    
+        │  INFO mdbook_pandoc::pandoc::renderer: Wrote output to book/markdown/pandoc-ir    
+        ├─ markdown/pandoc-ir
+        │ [ RawBlock (Format "html") "<details>\n<summary>\n"
+        │ , Div
+        │     ( "" , [ "details" ] , [] )
+        │     [ Div
+        │         ( "" , [ "summary" ] , [] )
+        │         [ Header
+        │             2
+        │             ( "book__markdown__src__chaptermd__heading"
+        │             , [ "unnumbered" , "unlisted" ]
+        │             , []
+        │             )
+        │             [ Str "Heading" ]
+        │         , Para [ Str "text" ]
+        │         ]
+        │     , RawBlock (Format "html") "</summary>\n<p>\n"
+        │     , Div
+        │         ( "" , [ "p" ] , [] )
+        │         [ Para [ Str "more" , Space , Strong [ Str "markdown" ] ] ]
+        │     ]
+        │ , RawBlock (Format "html") "</p>\n</details>\n"
+        │ , Para [ Str "outside" , Space , Str "divs" ]
+        │ ]
+        "###);
+    }
+
     #[test]
     /// Respect enabled/disabled extensions in Pandoc's `from` option
     fn extension_overrides() {

src/pandoc/extension.rs

@@ -9,6 +9,7 @@ pub enum Extension {
     Attributes,
     GfmAutoIdentifiers,
     RawAttribute,
+    FencedDivs,
     // TODO: pandoc's `rebase_relative_paths` extension works for Markdown links and images,
     // but not for raw HTML links and images. Switch if/when pandoc supports HTML as well.
     /// Treat paths as relative to the chapter containing them
@@ -27,6 +28,7 @@ impl Extension {
             Extension::Attributes => "attributes",
             Extension::GfmAutoIdentifiers => "gfm_auto_identifiers",
             Extension::RawAttribute => "raw_attribute",
+            Extension::FencedDivs => "fenced_divs",
             Extension::RebaseRelativePaths => "rebase_relative_paths",
         }
     }
@@ -41,6 +43,7 @@ impl Extension {
             Extension::Attributes => (2, 10, 1),
             Extension::GfmAutoIdentifiers => (2, 0, 0),
             Extension::RawAttribute => (2, 10, 1),
+            Extension::FencedDivs => (2, 0, 0),
             Extension::RebaseRelativePaths => (2, 14, 0),
         };
         Version {

src/preprocess.rs

@@ -672,6 +672,7 @@ struct PreprocessChapter<'book, 'preprocessor> {
     parser: Peekable<pulldown_cmark::OffsetIter<'book, pulldown_cmark::DefaultBrokenLinkCallback>>,
     matching_tags: Vec<pulldown_cmark::TagEnd>,
     encountered_h1: bool,
+    open_html_tags: Vec<html5gum::HtmlString>,
 }
 
 impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
@@ -697,6 +698,7 @@ impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
                 .peekable(),
             matching_tags: Default::default(),
             encountered_h1: false,
+            open_html_tags: Vec::new(),
         }
     }
 
@@ -1036,8 +1038,10 @@ impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
                         // Actually consume the item from the iterator
                         self.parser.next();
                     }
-                    html = self.preprocess_contiguous_html(html);
-                    Event::Html(html)
+                    for event in self.preprocess_contiguous_html(html, Event::Html) {
+                        co.yield_((event, None)).await
+                    }
+                    continue 'events;
                 }
                 Event::InlineHtml(mut html) => {
                     while let Some((Event::InlineHtml(more), _)) = self.parser.peek() {
@@ -1047,8 +1051,10 @@ impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
                         // Actually consume the item from the iterator
                         self.parser.next();
                     }
-                    html = self.preprocess_contiguous_html(html);
-                    Event::InlineHtml(html)
+                    for event in self.preprocess_contiguous_html(html, Event::InlineHtml) {
+                        co.yield_((event, None)).await
+                    }
+                    continue 'events;
                 }
                 Event::TaskListMarker(checked) => {
                     (self.preprocessor.ctx.pandoc).enable_extension(pandoc::Extension::TaskLists);
@@ -1060,7 +1066,11 @@ impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
         }
     }
 
-    fn preprocess_contiguous_html(&mut self, mut html: CowStr<'book>) -> CowStr<'book> {
+    fn preprocess_contiguous_html(
+        &mut self,
+        mut html: CowStr<'book>,
+        wrap_html: impl FnOnce(CowStr<'book>) -> pulldown_cmark::Event,
+    ) -> impl Iterator<Item = pulldown_cmark::Event<'book>> + '_ {
         if let OutputFormat::Latex { packages } = &mut self.preprocessor.ctx.output {
             static FONT_AWESOME_ICON: Lazy<Regex> = Lazy::new(|| {
                 Regex::new(r#"<i\s+class\s*=\s*"fa fa-(?P<icon>.*?)"(>\s*</i>|/>)"#).unwrap()
@@ -1078,7 +1088,60 @@ impl<'book, 'preprocessor> PreprocessChapter<'book, 'preprocessor> {
                 };
             }
         }
-        html
+        let already_open_tags = self.open_html_tags.len();
+        let mut still_open_tags = self.open_html_tags.len();
+        for node in html5gum::Tokenizer::new(html.as_ref()).infallible() {
+            match node {
+                html5gum::Token::StartTag(start) => {
+                    self.open_html_tags.push(start.name);
+                }
+                html5gum::Token::EndTag(end) => match self.open_html_tags.last() {
+                    Some(tag) if *tag == end.name => {
+                        self.open_html_tags.pop();
+                        still_open_tags = still_open_tags.min(self.open_html_tags.len());
+                    }
+                    _ => {}
+                },
+                _ => {}
+            }
+        }
+        use pulldown_cmark::Event;
+        let mut fenced_divs_available = || {
+            self.preprocessor
+                .ctx
+                .pandoc
+                .enable_extension(pandoc::Extension::FencedDivs)
+                .is_available()
+        };
+        let close_divs = {
+            let closed_tags = already_open_tags - still_open_tags;
+            (closed_tags > 0 && fenced_divs_available())
+                .then(|| {
+                    iter::once(Event::Text("\n\n".into()))
+                        .chain((0..closed_tags).map(|_| Event::Text(":::\n\n".into())))
+                        .chain(iter::once(Event::Text("\n\n".into())))
+                })
+                .into_iter()
+                .flatten()
+        };
+        let open_divs = {
+            let opened_tags = &self.open_html_tags[still_open_tags..];
+            (!opened_tags.is_empty() && fenced_divs_available())
+                .then(|| {
+                    iter::once(Event::Text("\n\n".into()))
+                        .chain(opened_tags.iter().map(|tag| {
+                            Event::Text(
+                                format!("::: {}\n\n", String::from_utf8_lossy(&tag.0)).into(),
+                            )
+                        }))
+                        .chain(iter::once(Event::Text("\n\n".into())))
+                })
+                .into_iter()
+                .flatten()
+        };
+        close_divs
+            .chain(iter::once(wrap_html(html)))
+            .chain(open_divs)
     }
 }