Merge pr/637: Index: keep level 3 and 4 topics in a run-in index (#637)

# Conflicts:
#	contributors/people.toml

contributors/people.toml

@@ -37,3 +37,6 @@ real_name = "Jeffrey Thayne"
 
 [people.Losminek]
 sync_github_name = true
+
+[people.webdevtodayjason]
+display_name = "Jason Brashear"

crates/doc/src/index.rs

@@ -184,10 +184,15 @@ fn entry_text(spec: &IndexSpec, n: &Node, page_name: &dyn Fn(usize) -> String) -
     t
 }
 
+// `build` limits topic paths to four levels, bounding this traversal.
+fn run_in_subtopics(spec: &IndexSpec, n: &Node, page_name: &dyn Fn(usize) -> String) -> Vec<String> {
+    n.children.values().flat_map(|c| [entry_text(spec, c, page_name)].into_iter().chain(run_in_subtopics(spec, c, page_name))).collect()
+}
+
 fn emit(spec: &IndexSpec, n: &Node, level: usize, page_name: &dyn Fn(usize) -> String, out: &mut Vec<(String, String)>) {
     if spec.run_in && level == 1 {
         let mut t = entry_text(spec, n, page_name);
-        let subs: Vec<String> = n.children.values().map(|c| entry_text(spec, c, page_name)).collect();
+        let subs = run_in_subtopics(spec, n, page_name);
         if !subs.is_empty() {
             t.push_str(": ");
             t.push_str(&subs.join(&spec.between_entries));
@@ -209,6 +214,19 @@ mod tests {
         Resolved { r: IndexRef { topics: topics.iter().map(|s| s.to_string()).collect(), sort: vec![], range }, pages }
     }
 
+    #[test]
+    fn run_in_keeps_all_topic_levels_in_sort_order() {
+        let refs = vec![
+            r(&["Typography", "kerning", "pairs", "optical"], IndexRange::CurrentPage, Some((4, 4))),
+            r(&["Typography", "kerning", "pairs"], IndexRange::CurrentPage, Some((2, 2))),
+            r(&["Typography", "leading"], IndexRange::CurrentPage, Some((6, 6))),
+            r(&["Typography", "kerning", "adjustment"], IndexRange::See("Spacing".into()), None),
+        ];
+        let spec = IndexSpec { run_in: true, title: String::new(), section_headings: false, between_entries: " / ".into(), ..IndexSpec::default() };
+        let out = build(&spec, &refs, &|p| (p + 1).to_string());
+        assert_eq!(out, [("Index Level 1".into(), "Typography: kerning / adjustment  See Spacing / pairs  3 / optical  5 / leading  7".into())]);
+    }
+
     #[test]
     fn builds_nested_index() {
         let refs = vec![