1 files changed, 160 insertions, 0 deletions
diff --git a/dom/quota/ResultExtensions.h b/dom/quota/ResultExtensions.h
new file mode 100644
index 0000000000..c19bf92661
--- /dev/null
+++ b/dom/quota/ResultExtensions.h
@@ -0,0 +1,160 @@
+/* -*- 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 DOM_QUOTA_QMRESULTINLINES_H_
+#define DOM_QUOTA_QMRESULTINLINES_H_
+
+#include "nsError.h"
+#include "mozilla/Result.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/dom/QMResult.h"
+#include "mozilla/dom/quota/Config.h"
+#include "mozilla/dom/quota/RemoveParen.h"
+
+#ifdef QM_ERROR_STACKS_ENABLED
+#  include "mozilla/ResultVariant.h"
+#endif
+
+namespace mozilla {
+
+// Allow bool errors to automatically convert to bool values, so MOZ_TRY/QM_TRY
+// can be used in bool returning methods with Result<T, bool> results.
+template <>
+class [[nodiscard]] GenericErrorResult<bool> {
+  bool mErrorValue;
+
+  template <typename V, typename E2>
+  friend class Result;
+
+ public:
+  explicit GenericErrorResult(bool aErrorValue) : mErrorValue(aErrorValue) {
+    MOZ_ASSERT(!aErrorValue);
+  }
+
+  GenericErrorResult(bool aErrorValue, const ErrorPropagationTag&)
+      : GenericErrorResult(aErrorValue) {}
+
+  MOZ_IMPLICIT operator bool() const { return mErrorValue; }
+};
+
+// Allow MOZ_TRY/QM_TRY to handle `bool` values.
+template <typename E = nsresult>
+inline Result<Ok, E> ToResult(bool aValue) {
+  if (aValue) {
+    return Ok();
+  }
+  return Err(ResultTypeTraits<E>::From(NS_ERROR_FAILURE));
+}
+
+constexpr nsresult ToNSResult(nsresult aError) { return aError; }
+
+#ifdef QM_ERROR_STACKS_ENABLED
+
+inline nsresult ToNSResult(const QMResult& aError) { return aError.NSResult(); }
+
+// Allow QMResult errors to use existing stack id and to increase the frame id
+// during error propagation.
+template <>
+class [[nodiscard]] GenericErrorResult<QMResult> {
+  QMResult mErrorValue;
+
+  template <typename V, typename E2>
+  friend class Result;
+
+ public:
+  explicit GenericErrorResult(const QMResult& aErrorValue)
+      : mErrorValue(aErrorValue) {
+    MOZ_ASSERT(NS_FAILED(aErrorValue.NSResult()));
+  }
+
+  explicit GenericErrorResult(QMResult&& aErrorValue)
+      : mErrorValue(std::move(aErrorValue)) {
+    MOZ_ASSERT(NS_FAILED(aErrorValue.NSResult()));
+  }
+
+  explicit GenericErrorResult(const QMResult& aErrorValue,
+                              const ErrorPropagationTag&)
+      : GenericErrorResult(aErrorValue.Propagate()) {}
+
+  explicit GenericErrorResult(QMResult&& aErrorValue,
+                              const ErrorPropagationTag&)
+      : GenericErrorResult(aErrorValue.Propagate()) {}
+
+  operator QMResult() const { return mErrorValue; }
+
+  operator nsresult() const { return mErrorValue.NSResult(); }
+};
+
+template <>
+struct ResultTypeTraits<QMResult> {
+  static QMResult From(nsresult aValue) { return ToQMResult(aValue); }
+
+  static QMResult From(const QMResult& aValue) { return aValue; }
+
+  static QMResult From(QMResult&& aValue) { return std::move(aValue); }
+};
+
+template <typename E>
+inline Result<Ok, E> ToResult(const QMResult& aValue) {
+  if (NS_FAILED(aValue.NSResult())) {
+    return Err(ResultTypeTraits<E>::From(aValue));
+  }
+  return Ok();
+}
+
+template <typename E>
+inline Result<Ok, E> ToResult(QMResult&& aValue) {
+  if (NS_FAILED(aValue.NSResult())) {
+    return Err(ResultTypeTraits<E>::From(aValue));
+  }
+  return Ok();
+}
+#endif
+
+template <typename E = nsresult, typename V, typename E2>
+inline Result<V, E> ToResultTransform(Result<V, E2>&& aValue) {
+  return std::forward<Result<V, E2>>(aValue).mapErr(
+      [](auto&& err) { return ResultTypeTraits<E>::From(err); });
+}
+
+// TODO: Maybe move this to mfbt/ResultExtensions.h
+template <typename R, typename Func, typename... Args>
+Result<R, nsresult> ToResultGet(const Func& aFunc, Args&&... aArgs) {
+  nsresult rv;
+  R res = aFunc(std::forward<Args>(aArgs)..., &rv);
+  if (NS_FAILED(rv)) {
+    return Err(rv);
+  }
+  return res;
+}
+
+}  // namespace mozilla
+
+// TODO: Maybe move this to mfbt/ResultExtensions.h
+#define MOZ_TO_RESULT(expr) ToResult(expr)
+
+#define QM_TO_RESULT(expr) ToResult<QMResult>(expr)
+
+#define QM_TO_RESULT_TRANSFORM(value) ToResultTransform<QMResult>(value)
+
+#define MOZ_TO_RESULT_GET_TYPED(resultType, ...) \
+  ::mozilla::ToResultGet<MOZ_REMOVE_PAREN(resultType)>(__VA_ARGS__)
+
+#define MOZ_TO_RESULT_INVOKE_TYPED(resultType, ...) \
+  ::mozilla::ToResultInvoke<MOZ_REMOVE_PAREN(resultType)>(__VA_ARGS__)
+
+#define QM_TO_RESULT_INVOKE_MEMBER(obj, methodname, ...)                 \
+  ::mozilla::ToResultInvokeMember<QMResult>(                             \
+      (obj), &::mozilla::detail::DerefedType<decltype(obj)>::methodname, \
+      ##__VA_ARGS__)
+
+#define QM_TO_RESULT_INVOKE_MEMBER_TYPED(resultType, obj, methodname, ...) \
+  (::mozilla::ToResultInvoke<resultType, QMResult>(                        \
+      ::std::mem_fn(                                                       \
+          &::mozilla::detail::DerefedType<decltype(obj)>::methodname),     \
+      (obj), ##__VA_ARGS__))
+
+#endif