Links: Find Linked Files resolves parent folders in a saved path

A saved link path such as `Disk:Projects:Art::photo.png` (classic Mac OS)
or `/old/Projects/Art/../photo.png` names a file in `Projects`. Ranking
the files found compared `Art` first, so a file under a folder named
`Art` came before one under `Projects`. The `::` runs and `..` components
are now resolved before the folder names are compared.

crates/engine/src/cmd/linkfiles.rs

@@ -177,9 +177,28 @@ fn find(s: &mut Session, p: &Value) -> Result<Value> {
 
 /// How many folder names the file at `found` has in common with the saved path `saved` (whichever
 /// system's separators it uses, [`vectorcraft_doc::links::path_separators`]), counted from the
-/// innermost out up to the first that differs, compared in lowercase.
+/// innermost out up to the first that differs, compared in lowercase. The saved path's parent
+/// components are resolved first: `..` in a `/` or `\` path, and each colon after the first in a
+/// run of colons in a classic Mac OS path (`Disk:Projects:Art::photo.png` is in `Projects`).
 fn shared_folders(saved: &str, found: &Path) -> usize {
-    let saved = saved.rsplit(vectorcraft_doc::links::path_separators(saved)).skip(1).filter(|c| !c.is_empty());
+    let separators = vectorcraft_doc::links::path_separators(saved);
+    let classic = separators == [':'];
+    let mut up = 0usize;
+    let saved = saved.rsplit(separators).skip(1).filter(move |c| {
+        let parent = if classic { c.is_empty() } else { *c == ".." };
+        if parent {
+            up += 1;
+            return false;
+        }
+        if c.is_empty() || *c == "." && !classic {
+            return false;
+        }
+        if up > 0 {
+            up -= 1;
+            return false;
+        }
+        true
+    });
     let found = found.parent().into_iter().flat_map(|p| p.components().rev()).map_while(|c| match c {
         Component::Normal(n) => n.to_str(),
         _ => None,

crates/engine/src/tests/linkfiles.rs

@@ -153,6 +153,37 @@ fn a_classic_mac_path_is_found_by_its_name_and_folders() {
     assert_eq!(found(&r, "photo.png", &root), files.map(|(p, k, c)| (p.to_string(), k.to_string(), c)));
 }
 
+/// The folders a saved path shares with a file found are counted after its parent components are
+/// resolved: `Art::` in a classic Mac OS path and `Art/..` in any other path go back to `Projects`.
+#[test]
+fn parent_components_in_a_saved_path_are_resolved_before_ranking() {
+    for (tag, saved) in [("classic-up", "Old Disk:Projects:Art::photo.png"), ("slash-up", "/old/Projects/Art/../photo.png")] {
+        let root = folder(tag);
+        let mut s = session_for(&root);
+        let photo = png(50, 30, BLUE);
+        write(&root.join("orig/photo.png"), &photo);
+        let id = placed(&mut s, &root.join("orig/photo.png"));
+        s.edit("saved path", |d, _| {
+            if let NodeKind::Image(im) = &mut d.node_mut(NodeId(id)).unwrap().kind {
+                im.link.as_mut().unwrap().path = saved.into();
+            }
+            Ok(())
+        })
+        .unwrap();
+        std::fs::remove_dir_all(root.join("orig")).unwrap();
+        let search = root.join("search");
+        let mut changed = photo.clone();
+        *changed.last_mut().unwrap() ^= 1;
+        write(&search.join("Art/photo.png"), &changed);
+        write(&search.join("Projects/photo.png"), &changed);
+        s.execute("links.findFiles", &json!({"folder": search})).unwrap();
+        let r = finished(&mut s);
+        assert_eq!(r["state"].as_str(), Some("done"), "{saved}: {r}");
+        let files = [("search/Projects/photo.png", "name", false), ("search/Art/photo.png", "name", false)];
+        assert_eq!(found(&r, "photo.png", &root), files.map(|(p, k, c)| (p.to_string(), k.to_string(), c)), "{saved}");
+    }
+}
+
 /// Without `ids`, a search looks for the files that can't be found; with them, for those objects'
 /// files, whatever their status.
 #[test]