diff options
author | rsgowman <rgowman@google.com> | 2018-03-19 10:19:20 -0400 |
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committer | GitHub <noreply@github.com> | 2018-03-19 10:19:20 -0400 |
commit | 529666594951b86604730a8b400f71d7eedd1e85 (patch) | |
tree | f645396ea3485cd838db13ee715816cbca1bc334 /Firestore/core/src/firebase/firestore/util/statusor_internals.h | |
parent | 4e7296b080b9c8cea13e5e5eeee65f4312fb5e8a (diff) |
Add Status and StatusOr (#935)
* Pull in status files from tensorflow
* Add missing dependency to immutable library
Diffstat (limited to 'Firestore/core/src/firebase/firestore/util/statusor_internals.h')
-rw-r--r-- | Firestore/core/src/firebase/firestore/util/statusor_internals.h | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/Firestore/core/src/firebase/firestore/util/statusor_internals.h b/Firestore/core/src/firebase/firestore/util/statusor_internals.h new file mode 100644 index 0000000..d6c8de1 --- /dev/null +++ b/Firestore/core/src/firebase/firestore/util/statusor_internals.h @@ -0,0 +1,258 @@ +/* + * Copyright 2017, 2018 Google + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STATUSOR_INTERNALS_H_ +#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STATUSOR_INTERNALS_H_ + +#include <utility> + +#include "Firestore/core/src/firebase/firestore/util/status.h" +#include "absl/base/attributes.h" + +namespace firebase { +namespace firestore { +namespace util { +namespace internal_statusor { + +class Helper { + public: + // Move type-agnostic error handling to the .cc. + static void HandleInvalidStatusCtorArg(Status*); + ABSL_ATTRIBUTE_NORETURN static void Crash(const Status& status); +}; + +// Construct an instance of T in `p` through placement new, passing Args... to +// the constructor. +// This abstraction is here mostly for the gcc performance fix. +template <typename T, typename... Args> +void PlacementNew(void* p, Args&&... args) { +#if defined(__GNUC__) && !defined(__clang__) + // Teach gcc that 'p' cannot be null, fixing code size issues. + if (p == nullptr) __builtin_unreachable(); +#endif + new (p) T(std::forward<Args>(args)...); +} + +// Helper base class to hold the data and all operations. +// We move all this to a base class to allow mixing with the appropriate +// TraitsBase specialization. +template <typename T> +class StatusOrData { + template <typename U> + friend class StatusOrData; + + public: + StatusOrData() = delete; + + StatusOrData(const StatusOrData& other) { + if (other.ok()) { + MakeValue(other.data_); + MakeStatus(); + } else { + MakeStatus(other.status_); + } + } + + StatusOrData(StatusOrData&& other) noexcept { + if (other.ok()) { + MakeValue(std::move(other.data_)); + MakeStatus(); + } else { + MakeStatus(std::move(other.status_)); + } + } + + template <typename U> + StatusOrData(const StatusOrData<U>& other) { + if (other.ok()) { + MakeValue(other.data_); + MakeStatus(); + } else { + MakeStatus(other.status_); + } + } + + template <typename U> + StatusOrData(StatusOrData<U>&& other) { + if (other.ok()) { + MakeValue(std::move(other.data_)); + MakeStatus(); + } else { + MakeStatus(std::move(other.status_)); + } + } + + explicit StatusOrData(const T& value) : data_(value) { + MakeStatus(); + } + explicit StatusOrData(T&& value) : data_(std::move(value)) { + MakeStatus(); + } + + explicit StatusOrData(const Status& status) : status_(status) { + EnsureNotOk(); + } + explicit StatusOrData(Status&& status) : status_(std::move(status)) { + EnsureNotOk(); + } + + StatusOrData& operator=(const StatusOrData& other) { + if (this == &other) return *this; + if (other.ok()) + Assign(other.data_); + else + Assign(other.status_); + return *this; + } + + StatusOrData& operator=(StatusOrData&& other) { + if (this == &other) return *this; + if (other.ok()) + Assign(std::move(other.data_)); + else + Assign(std::move(other.status_)); + return *this; + } + + ~StatusOrData() { + if (ok()) { + status_.~Status(); + data_.~T(); + } else { + status_.~Status(); + } + } + + void Assign(const T& value) { + if (ok()) { + data_.~T(); + MakeValue(value); + } else { + MakeValue(value); + status_ = Status::OK(); + } + } + + void Assign(T&& value) { + if (ok()) { + data_.~T(); + MakeValue(std::move(value)); + } else { + MakeValue(std::move(value)); + status_ = Status::OK(); + } + } + + void Assign(const Status& status) { + Clear(); + status_ = status; + EnsureNotOk(); + } + + void Assign(Status&& status) { + Clear(); + status_ = std::move(status); + EnsureNotOk(); + } + + bool ok() const { + return status_.ok(); + } + + protected: + // status_ will always be active after the constructor. + // We make it a union to be able to initialize exactly how we need without + // waste. + // Eg. in the copy constructor we use the default constructor of Status in + // the ok() path to avoid an extra Ref call. + union { + Status status_; + }; + + // data_ is active iff status_.ok()==true + struct Dummy {}; + union { + // When T is const, we need some non-const object we can cast to void* for + // the placement new. dummy_ is that object. + Dummy dummy_; + T data_; + }; + + void Clear() { + if (ok()) data_.~T(); + } + + void EnsureOk() const { + if (!ok()) Helper::Crash(status_); + } + + void EnsureNotOk() { + if (ok()) Helper::HandleInvalidStatusCtorArg(&status_); + } + + // Construct the value (ie. data_) through placement new with the passed + // argument. + template <typename Arg> + void MakeValue(Arg&& arg) { + internal_statusor::PlacementNew<T>(&dummy_, std::forward<Arg>(arg)); + } + + // Construct the status (ie. status_) through placement new with the passed + // argument. + template <typename... Args> + void MakeStatus(Args&&... args) { + internal_statusor::PlacementNew<Status>(&status_, + std::forward<Args>(args)...); + } +}; + +// Helper base class to allow implicitly deleted constructors and assignment +// operations in StatusOr. +// TraitsBase will explicitly delete what it can't support and StatusOr will +// inherit that behavior implicitly. +template <bool Copy, bool Move> +struct TraitsBase { + TraitsBase() = default; + TraitsBase(const TraitsBase&) = default; + TraitsBase(TraitsBase&&) = default; + TraitsBase& operator=(const TraitsBase&) = default; + TraitsBase& operator=(TraitsBase&&) = default; +}; + +template <> +struct TraitsBase<false, true> { + TraitsBase() = default; + TraitsBase(const TraitsBase&) = delete; + TraitsBase(TraitsBase&&) = default; + TraitsBase& operator=(const TraitsBase&) = delete; + TraitsBase& operator=(TraitsBase&&) = default; +}; + +template <> +struct TraitsBase<false, false> { + TraitsBase() = default; + TraitsBase(const TraitsBase&) = delete; + TraitsBase(TraitsBase&&) = delete; + TraitsBase& operator=(const TraitsBase&) = delete; + TraitsBase& operator=(TraitsBase&&) = delete; +}; + +} // namespace internal_statusor +} // namespace util +} // namespace firestore +} // namespace firebase + +#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STATUSOR_INTERNALS_H_ |