1 files changed, 65 insertions, 0 deletions
diff --git a/js/public/SweepingAPI.h b/js/public/SweepingAPI.h
new file mode 100644
index 000000000..0eb29ae41
--- /dev/null
+++ b/js/public/SweepingAPI.h
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_SweepingAPI_h
+#define js_SweepingAPI_h
+
+#include "js/HeapAPI.h"
+
+namespace js {
+template <typename T>
+class WeakCacheBase {};
+} // namespace js
+
+namespace JS {
+template <typename T> class WeakCache;
+
+namespace shadow {
+JS_PUBLIC_API(void)
+RegisterWeakCache(JS::Zone* zone, JS::WeakCache<void*>* cachep);
+} // namespace shadow
+
+// A WeakCache stores the given Sweepable container and links itself into a
+// list of such caches that are swept during each GC.
+template <typename T>
+class WeakCache : public js::WeakCacheBase<T>,
+                  private mozilla::LinkedListElement<WeakCache<T>>
+{
+    friend class mozilla::LinkedListElement<WeakCache<T>>;
+    friend class mozilla::LinkedList<WeakCache<T>>;
+
+    WeakCache() = delete;
+    WeakCache(const WeakCache&) = delete;
+
+    using SweepFn = void (*)(T*);
+    SweepFn sweeper;
+    T cache;
+
+  public:
+    using Type = T;
+
+    template <typename U>
+    WeakCache(Zone* zone, U&& initial)
+      : cache(mozilla::Forward<U>(initial))
+    {
+        sweeper = GCPolicy<T>::sweep;
+        shadow::RegisterWeakCache(zone, reinterpret_cast<WeakCache<void*>*>(this));
+    }
+    WeakCache(WeakCache&& other)
+      : sweeper(other.sweeper),
+        cache(mozilla::Move(other.cache))
+    {
+    }
+
+    const T& get() const { return cache; }
+    T& get() { return cache; }
+
+    void sweep() { sweeper(&cache); }
+};
+
+} // namespace JS
+
+#endif // js_SweepingAPI_h