1 files changed, 48 insertions, 0 deletions
diff --git a/xpcom/threads/MozPromiseInlines.h b/xpcom/threads/MozPromiseInlines.h
new file mode 100644
index 0000000000..def7e90461
--- /dev/null
+++ b/xpcom/threads/MozPromiseInlines.h
@@ -0,0 +1,48 @@
+/* -*- 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 MozPromiseInlines_h_
+#define MozPromiseInlines_h_
+
+#include <type_traits>
+
+#include "mozilla/MozPromise.h"
+#include "mozilla/dom/PrimitiveConversions.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/PromiseNativeHandler.h"
+
+namespace mozilla {
+
+// Creates a C++ MozPromise from its JS counterpart, dom::Promise.
+// FromDomPromise currently only supports primitive types (int8/16/32, float,
+// double) And the reject value type must be a nsresult.
+template <typename ResolveValueT, typename RejectValueT, bool IsExclusive>
+RefPtr<MozPromise<ResolveValueT, RejectValueT, IsExclusive>>
+MozPromise<ResolveValueT, RejectValueT, IsExclusive>::FromDomPromise(
+    dom::Promise* aDOMPromise) {
+  static_assert(std::is_same_v<RejectValueType, nsresult>,
+                "Reject type must be nsresult");
+  RefPtr<Private> p = new Private(__func__);
+  RefPtr<dom::DomPromiseListener> listener = new dom::DomPromiseListener(
+      [p](JSContext* aCx, JS::Handle<JS::Value> aValue) {
+        ResolveValueT value;
+        bool ok = dom::ValueToPrimitive<ResolveValueT,
+                                        dom::ConversionBehavior::eDefault>(
+            aCx, aValue, "Resolution value", &value);
+        if (!ok) {
+          p->Reject(NS_ERROR_FAILURE, __func__);
+          return;
+        }
+        p->Resolve(value, __func__);
+      },
+      [p](nsresult aError) { p->Reject(aError, __func__); });
+  aDOMPromise->AppendNativeHandler(listener);
+  return p;
+}
+
+}  // namespace mozilla
+
+#endif