LibJS: Notify WeakSets when heap cells are sweeped

This is an implementation of the following optional optimization:
https://tc39.es/ecma262/#sec-weakref-execution

2 files changed, 13 insertions, 3 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/WeakSet.cpp b/Userland/Libraries/LibJS/Runtime/WeakSet.cpp
index 50bf41c0ba..ff64c0858d 100644
--- a/Userland/Libraries/LibJS/Runtime/WeakSet.cpp
+++ b/Userland/Libraries/LibJS/Runtime/WeakSet.cpp
@@ -16,10 +16,18 @@ WeakSet* WeakSet::create(GlobalObject& global_object)
 WeakSet::WeakSet(Object& prototype)
     : Object(prototype)
 {
+    heap().did_create_weak_set({}, *this);
 }
 
 WeakSet::~WeakSet()
 {
+    heap().did_destroy_weak_set({}, *this);
+}
+
+void WeakSet::remove_sweeped_cells(Badge<Heap>, Vector<Cell*>& cells)
+{
+    for (auto* cell : cells)
+        m_values.remove(cell);
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/WeakSet.h b/Userland/Libraries/LibJS/Runtime/WeakSet.h
index f8c06ad017..0062d4eef4 100644
--- a/Userland/Libraries/LibJS/Runtime/WeakSet.h
+++ b/Userland/Libraries/LibJS/Runtime/WeakSet.h
@@ -21,11 +21,13 @@ public:
     explicit WeakSet(Object& prototype);
     virtual ~WeakSet() override;
 
-    HashTable<Object*> const& values() const { return m_values; };
-    HashTable<Object*>& values() { return m_values; };
+    HashTable<Cell*> const& values() const { return m_values; };
+    HashTable<Cell*>& values() { return m_values; };
+
+    void remove_sweeped_cells(Badge<Heap>, Vector<Cell*>&);
 
 private:
-    HashTable<Object*> m_values;
+    HashTable<Cell*> m_values; // This stores Cell pointers instead of Object pointers to aide with sweeping
 };
 
 }