fix(html): backtrack jsdoc summary ending with ':' to last '.'

Author: nanookclaw

src/html/comrak.rs

@@ -63,6 +63,118 @@ fn walk_node_title<'a>(node: &'a AstNode<'a>) {
   }
 }
 
+/// Append the inline plain-text contribution of `node` to `out`.
+/// Counts `NodeValue::Text` and `NodeValue::Code` literals, and treats
+/// `NodeValue::SoftBreak` as a single space. Other inline containers
+/// (Emph, Strong, Link, etc.) descend into their children.
+fn collect_inline_plain_text<'a>(node: &'a AstNode<'a>, out: &mut String) {
+  match &node.data.borrow().value {
+    NodeValue::Text(t) => out.push_str(t),
+    NodeValue::Code(c) => out.push_str(&c.literal),
+    NodeValue::SoftBreak => out.push(' '),
+    _ => {
+      for child in node.children() {
+        collect_inline_plain_text(child, out);
+      }
+    }
+  }
+}
+
+/// Truncate the inline tree rooted at `node` so that, in document order,
+/// the cumulative plain-text contribution is exactly `target` bytes.
+/// Returns true once `*offset >= target`, signalling to callers that the
+/// rest of the tree should be detached.
+fn truncate_inline_to<'a>(
+  node: &'a AstNode<'a>,
+  offset: &mut usize,
+  target: usize,
+) -> bool {
+  if *offset >= target {
+    return true;
+  }
+
+  enum Kind {
+    Text,
+    Code,
+    SoftBreak,
+    Container,
+  }
+
+  let kind = match &node.data.borrow().value {
+    NodeValue::Text(_) => Kind::Text,
+    NodeValue::Code(_) => Kind::Code,
+    NodeValue::SoftBreak => Kind::SoftBreak,
+    _ => Kind::Container,
+  };
+
+  match kind {
+    Kind::Text => {
+      let mut data = node.data.borrow_mut();
+      if let NodeValue::Text(t) = &mut data.value {
+        let len = t.len();
+        if *offset + len <= target {
+          *offset += len;
+        } else {
+          let take = target - *offset;
+          t.truncate(take);
+          *offset = target;
+        }
+      }
+    }
+    Kind::Code => {
+      let mut data = node.data.borrow_mut();
+      if let NodeValue::Code(c) = &mut data.value {
+        let len = c.literal.len();
+        if *offset + len <= target {
+          *offset += len;
+        } else {
+          let take = target - *offset;
+          c.literal.truncate(take);
+          *offset = target;
+        }
+      }
+    }
+    Kind::SoftBreak => {
+      *offset += 1;
+    }
+    Kind::Container => {
+      let children: Vec<_> = node.children().collect();
+      let mut done = false;
+      for child in children {
+        if done {
+          child.detach();
+        } else {
+          done = truncate_inline_to(child, offset, target);
+        }
+      }
+    }
+  }
+
+  *offset >= target
+}
+
+/// If the first paragraph's trimmed plain text ends with `':'` and
+/// contains a `'.'`, truncate the paragraph so the rendered output ends
+/// right after the last `'.'`. Does nothing otherwise. See
+/// <https://github.com/denoland/deno_doc/issues/633>.
+fn truncate_title_summary_trailing_colon<'a>(paragraph: &'a AstNode<'a>) {
+  let mut plain = String::new();
+  collect_inline_plain_text(paragraph, &mut plain);
+
+  let trimmed = plain.trim_end_matches(|c: char| c.is_ascii_whitespace());
+  if !trimmed.ends_with(':') {
+    return;
+  }
+
+  let Some(last_dot) = trimmed.rfind('.') else {
+    return;
+  };
+
+  let target = last_dot + 1;
+  let mut offset = 0;
+  truncate_inline_to(paragraph, &mut offset, target);
+}
+
 pub fn render_node<'a>(
   node: &'a AstNode<'a>,
   options: &comrak::Options,
@@ -152,6 +264,7 @@ pub fn create_renderer(
         walk_node_title(root);
 
         if let Some(child) = root.first_child() {
+          truncate_title_summary_trailing_colon(child);
           render_node(child, &options, &plugins)
         } else {
           return None;
@@ -254,3 +367,63 @@ impl SyntaxHighlighterAdapter for ComrakHighlightWrapperAdapter {
     }
   }
 }
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  fn render_title_only(md: &str) -> String {
+    let mut options = default_options();
+    options.render.escape = true;
+
+    let arena = Arena::new();
+    let root = comrak::parse_document(&arena, md, &options);
+    walk_node_title(root);
+
+    let Some(child) = root.first_child() else {
+      return String::new();
+    };
+    truncate_title_summary_trailing_colon(child);
+    render_node(child, &options, &comrak::Plugins::default())
+  }
+
+  #[test]
+  fn title_summary_trailing_colon_with_period_truncates_to_last_period() {
+    let html = render_title_only("This is a summary. It says:");
+    assert_eq!(html.trim(), "<p>This is a summary.</p>");
+  }
+
+  #[test]
+  fn title_summary_trailing_colon_without_period_left_unchanged() {
+    let html = render_title_only("This is a summary:");
+    assert_eq!(html.trim(), "<p>This is a summary:</p>");
+  }
+
+  #[test]
+  fn title_summary_no_trailing_colon_left_unchanged() {
+    let html = render_title_only("This is a summary.");
+    assert_eq!(html.trim(), "<p>This is a summary.</p>");
+  }
+
+  #[test]
+  fn title_summary_trailing_colon_after_code_span_truncates() {
+    // Period before the code+colon tail — backtracking should drop the
+    // code span and trailing colon entirely.
+    let html = render_title_only("First. Then `something`:");
+    assert_eq!(html.trim(), "<p>First.</p>");
+  }
+
+  #[test]
+  fn title_summary_trailing_colon_after_emph_truncates() {
+    let html = render_title_only("First. Then *emph*:");
+    assert_eq!(html.trim(), "<p>First.</p>");
+  }
+
+  #[test]
+  fn title_summary_period_inside_code_span_keeps_code_up_to_period() {
+    // The last '.' lives inside a code span; truncation lands exactly at
+    // the end of that span and drops the following text+colon.
+    let html = render_title_only("Some `code.` text:");
+    assert_eq!(html.trim(), "<p>Some <code>code.</code></p>");
+  }
+}