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-rw-r--r--js/xpconnect/src/xpcObjectHelper.h68
1 files changed, 68 insertions, 0 deletions
diff --git a/js/xpconnect/src/xpcObjectHelper.h b/js/xpconnect/src/xpcObjectHelper.h
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+++ b/js/xpconnect/src/xpcObjectHelper.h
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+/* -*- 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 xpcObjectHelper_h
+#define xpcObjectHelper_h
+
+// Including 'windows.h' will #define GetClassInfo to something else.
+#ifdef XP_WIN
+# ifdef GetClassInfo
+# undef GetClassInfo
+# endif
+#endif
+
+#include "mozilla/Attributes.h"
+#include <stdint.h>
+#include "nsCOMPtr.h"
+#include "nsIClassInfo.h"
+#include "nsISupports.h"
+#include "nsIXPCScriptable.h"
+#include "nsWrapperCache.h"
+
+class xpcObjectHelper {
+ public:
+ explicit xpcObjectHelper(nsISupports* aObject,
+ nsWrapperCache* aCache = nullptr)
+ : mObject(aObject), mCache(aCache) {
+ if (!mCache && aObject) {
+ CallQueryInterface(aObject, &mCache);
+ }
+ }
+
+ nsISupports* Object() { return mObject; }
+
+ nsIClassInfo* GetClassInfo() {
+ if (!mClassInfo) {
+ mClassInfo = do_QueryInterface(mObject);
+ }
+ return mClassInfo;
+ }
+
+ // We assert that we can reach an nsIXPCScriptable somehow.
+ uint32_t GetScriptableFlags() {
+ nsCOMPtr<nsIXPCScriptable> sinfo = do_QueryInterface(mObject);
+
+ // We should have something by now.
+ MOZ_ASSERT(sinfo);
+
+ // Grab the flags.
+ return sinfo->GetScriptableFlags();
+ }
+
+ nsWrapperCache* GetWrapperCache() { return mCache; }
+
+ private:
+ xpcObjectHelper(xpcObjectHelper& aOther) = delete;
+
+ nsISupports* MOZ_UNSAFE_REF(
+ "xpcObjectHelper has been specifically optimized "
+ "to avoid unnecessary AddRefs and Releases. "
+ "(see bug 565742)") mObject;
+ nsWrapperCache* mCache;
+ nsCOMPtr<nsIClassInfo> mClassInfo;
+};
+
+#endif