1 files changed, 52 insertions, 0 deletions
diff --git a/xpcom/base/JSONStringWriteFuncs.h b/xpcom/base/JSONStringWriteFuncs.h
new file mode 100644
index 0000000000..65b688788c
--- /dev/null
+++ b/xpcom/base/JSONStringWriteFuncs.h
@@ -0,0 +1,52 @@
+/* -*- 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 JSONSTRINGWRITEFUNCS_H
+#define JSONSTRINGWRITEFUNCS_H
+
+#include "mozilla/JSONWriter.h"
+#include "nsString.h"
+
+#include <type_traits>
+
+namespace mozilla {
+
+// JSONWriteFunc that writes to an owned string.
+template <typename StringType>
+class JSONStringWriteFunc final : public JSONWriteFunc {
+  static_assert(
+      !std::is_reference_v<StringType>,
+      "Use JSONStringRefWriteFunc instead to write to a referenced string");
+
+ public:
+  JSONStringWriteFunc() = default;
+
+  void Write(const Span<const char>& aStr) final { mString.Append(aStr); }
+
+  const StringType& StringCRef() const { return mString; }
+
+  StringType&& StringRRef() && { return std::move(mString); }
+
+ private:
+  StringType mString;
+};
+
+// JSONWriteFunc that writes to a given nsACString reference.
+class JSONStringRefWriteFunc final : public JSONWriteFunc {
+ public:
+  MOZ_IMPLICIT JSONStringRefWriteFunc(nsACString& aString) : mString(aString) {}
+
+  void Write(const Span<const char>& aStr) final { mString.Append(aStr); }
+
+  const nsACString& StringCRef() const { return mString; }
+
+ private:
+  nsACString& mString;
+};
+
+}  // namespace mozilla
+
+#endif  // JSONSTRINGWRITEFUNCS_H