1 files changed, 36 insertions, 0 deletions
diff --git a/xpcom/ds/nsStaticAtomUtils.h b/xpcom/ds/nsStaticAtomUtils.h
new file mode 100644
index 0000000000..8c766f63e1
--- /dev/null
+++ b/xpcom/ds/nsStaticAtomUtils.h
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 nsStaticAtomUtils_h
+#define nsStaticAtomUtils_h
+
+#include <stdint.h>
+#include "nsAtom.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Maybe.h"
+
+// This class holds basic operations on arrays of static atoms.
+class nsStaticAtomUtils {
+ public:
+  static mozilla::Maybe<uint32_t> Lookup(nsAtom* aAtom,
+                                         const nsStaticAtom* aAtoms,
+                                         uint32_t aCount) {
+    if (aAtom->IsStatic()) {
+      ptrdiff_t index = aAtom->AsStatic() - aAtoms;
+      if (index >= 0 && index < static_cast<ptrdiff_t>(aCount)) {
+        return mozilla::Some(static_cast<uint32_t>(index));
+      }
+    }
+    return mozilla::Nothing();
+  }
+
+  static bool IsMember(nsAtom* aAtom, const nsStaticAtom* aAtoms,
+                       uint32_t aCount) {
+    return Lookup(aAtom, aAtoms, aCount).isSome();
+  }
+};
+
+#endif  // nsStaticAtomUtils_h