SERVER-29286 import and use mozjs-60

1 files changed, 63 insertions, 0 deletions

diff --git a/src/third_party/mozjs-60/extract/js/src/ds/Nestable.h b/src/third_party/mozjs-60/extract/js/src/ds/Nestable.h
new file mode 100644
index 00000000000..c02264abcea
--- /dev/null
+++ b/src/third_party/mozjs-60/extract/js/src/ds/Nestable.h
@@ -0,0 +1,63 @@
+/* -*- 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 ds_Nestable_h
+#define ds_Nestable_h
+
+namespace js {
+
+// A base class for nestable structures.
+template <typename Concrete>
+class MOZ_STACK_CLASS Nestable
+{
+    Concrete** stack_;
+    Concrete*  enclosing_;
+
+  protected:
+    explicit Nestable(Concrete** stack)
+      : stack_(stack),
+        enclosing_(*stack)
+    {
+        *stack_ = static_cast<Concrete*>(this);
+    }
+
+    // These method are protected. Some derived classes, such as ParseContext,
+    // do not expose the ability to walk the stack.
+    Concrete* enclosing() const {
+        return enclosing_;
+    }
+
+    template <typename Predicate /* (Concrete*) -> bool */>
+    static Concrete* findNearest(Concrete* it, Predicate predicate) {
+        while (it && !predicate(it))
+            it = it->enclosing();
+        return it;
+    }
+
+    template <typename T>
+    static T* findNearest(Concrete* it) {
+        while (it && !it->template is<T>())
+            it = it->enclosing();
+        return it ? &it->template as<T>() : nullptr;
+    }
+
+    template <typename T, typename Predicate /* (T*) -> bool */>
+    static T* findNearest(Concrete* it, Predicate predicate) {
+        while (it && (!it->template is<T>() || !predicate(&it->template as<T>())))
+            it = it->enclosing();
+        return it ? &it->template as<T>() : nullptr;
+    }
+
+  public:
+    ~Nestable() {
+        MOZ_ASSERT(*stack_ == static_cast<Concrete*>(this));
+        *stack_ = enclosing_;
+    }
+};
+
+} // namespace js
+
+#endif /* ds_Nestable_h */