Match selectors inside ShadowRoot trees

crates/obscura-dom/src/selector.rs

@@ -743,6 +743,29 @@ impl DomTree {
         Ok(results)
     }
 
+    /// Test one element as the selector subject, including when it is
+    /// detached or is a direct child of a shadow-tree compatibility root.
+    pub fn matches_selector(&self, nid: NodeId, selector: &str) -> Result<bool, String> {
+        if !self.with_node(nid, |node| node.is_element()).unwrap_or(false) {
+            return Ok(false);
+        }
+        let selector_list = parse_selector(selector)?;
+        let mut caches = selectors::context::SelectorCaches::default();
+        let mut context = MatchingContext::new(
+            MatchingMode::Normal,
+            None,
+            &mut caches,
+            QuirksMode::NoQuirks,
+            NeedsSelectorFlags::No,
+            MatchingForInvalidation::No,
+        );
+        Ok(selectors::matching::matches_selector_list(
+            &selector_list,
+            &DomElement::new(self, nid),
+            &mut context,
+        ))
+    }
+
     /// Parse a single selector once for repeated single-element matching, and
     /// precompute its specificity, ancestor hashes, and "subject key" (the
     /// rightmost id/class/tag used to bucket the rule for fast candidate

crates/obscura-js/js/bootstrap.js

@@ -2059,13 +2059,7 @@ class Element extends Node {
       if (rest === "") return true;
       return this.matches(rest);
     }
-    const parent = this.parentNode;
-    if (!parent || !parent.querySelectorAll) return false;
-    const matches = parent.querySelectorAll(s);
-    for (let i = 0; i < matches.length; i++) {
-      if (matches[i]._nid === this._nid) return true;
-    }
-    return false;
+    return _dom("matches_selector", this._nid, String(s)) === "true";
   }
   closest(s) {
     let el = this;

crates/obscura-js/src/ops.rs

@@ -288,6 +288,10 @@ fn op_dom_inner(state: &OpState, cmd: String, arg1: String, arg2: String) -> Str
                 .map(|ids| ids.iter().map(|id| id.index() as i32).collect()).unwrap_or_default();
             serde_json::to_string(&ids).unwrap_or("[]".into())
         }
+        "matches_selector" => {
+            let nid = NodeId::new(arg1.parse::<u32>().unwrap_or(0));
+            dom.matches_selector(nid, &arg2).unwrap_or(false).to_string()
+        }
         "node_type" => {
             let nid = arg1.parse::<u32>().unwrap_or(0);
             dom.with_node(NodeId::new(nid), |n| match &n.data {

crates/obscura-js/src/runtime.rs

@@ -1991,7 +1991,10 @@ mod tests {
                 const parsed = [
                     inside.parentNode === root,
                     inside.getRootNode() === root,
-                    root.textContent
+                    root.textContent,
+                    inside.matches("span#inside"),
+                    root.querySelector("span#inside") === inside,
+                    root.querySelectorAll("span#inside").length === 1
                 ];
 
                 const a = document.createElement("a");
@@ -2059,7 +2062,7 @@ mod tests {
                 ],
                 [true, true, true],
                 [true, true, true],
-                [true, true, "inside"],
+                [true, true, "inside", true, true, true],
                 ["b", "a", "i"],
                 [["b", "a", "x-one", "x-two", "i"], 0, true, true],
                 [["a", "x-one", "x-two", "b"], true, true],