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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMECAST_CAST_CORE_GRPC_GRPC_STATUS_OR_H_
#define CHROMECAST_CAST_CORE_GRPC_GRPC_STATUS_OR_H_
#include <grpcpp/support/status.h>
#include <string>
#include <type_traits>
#include <optional>
#include "base/check.h"
namespace cast {
namespace utils {
// Converts grpc::Status to a string message.
std::string GrpcStatusToString(const grpc::Status& status);
// Holds a value of type T with grpc::Status::OK or an error grpc::Status.
template <typename T,
typename std::enable_if<!std::is_reference<T>::value, T*>::type =
nullptr>
class GrpcStatusOr {
public:
GrpcStatusOr() : status_(grpc::StatusCode::UNKNOWN, "") {}
// Constructs GrpcStatusOr from an error |status_code|.
GrpcStatusOr(grpc::StatusCode status_code) // NOLINT
: GrpcStatusOr(status_code, "") {}
// Constructs GrpcStatusOr from an error |status_code| and |error_message|.
GrpcStatusOr(grpc::StatusCode status_code, const std::string& error_message)
: status_(status_code, error_message) {
DCHECK(!status_.ok());
}
// Constructs GrpcStatusOr from an error |status|.
GrpcStatusOr(grpc::Status status) // NOLINT
: status_(std::move(status)) {
DCHECK(!status_.ok());
}
// Constructs GrpcStatusOr from the |data|. Status code is set to OK.
GrpcStatusOr(const T& data) // NOLINT
: status_(grpc::Status::OK), data_(data) {}
// Constructs GrpcStatusOr from the |data|. Status code is set to OK.
GrpcStatusOr(T&& data) // NOLINT
: status_(grpc::Status::OK), data_(std::move(data)) {}
// Constructs GrpcStatusOr from the |data| of type U that is possible to
// convert to type |T|. For example, std::unique_ptr<MockClass> converted to
// std::unique_ptr<Class>. Status code is set to OK.
template <typename U,
typename std::enable_if<std::is_constructible<T, U>::value,
U>::type* = nullptr>
GrpcStatusOr(U&& data) // NOLINT
: status_(grpc::Status::OK), data_(std::forward<U>(data)) {}
GrpcStatusOr(GrpcStatusOr&&) = default;
GrpcStatusOr& operator=(GrpcStatusOr&&) = default;
GrpcStatusOr(const GrpcStatusOr&) = default;
GrpcStatusOr& operator=(const GrpcStatusOr&) = default;
~GrpcStatusOr() = default;
// Returns if status is OK.
bool ok() const { return status_.ok(); }
// Returns const reference to gRPC status.
const grpc::Status& status() const& { return status_; }
// Returns r-value to gRPC status.
grpc::Status&& status() && { return std::move(status_); }
// Returns the pointer to the stored data. Checks if status is not OK.
T* operator->() {
DCHECK(status_.ok());
return &*data_;
}
// Returns the const pointer to the stored data. Checks if status is not OK.
const T* operator->() const {
DCHECK(status_.ok());
return &*data_;
}
// Returns the const reference to the stored data. Checks if status is not OK.
const T& operator*() const& {
DCHECK(status_.ok());
return *data_;
}
// Returns the lvalue-ref to the underlying value. Checks if status is not OK.
const T& value() const& {
DCHECK(status_.ok());
return *data_;
}
// Returns the rvalue-ref to the underlying value. To trigger this accessor,
// the status object needs to be moved first: std::move(status_).value().
// Checks if status is not OK.
T&& value() && {
DCHECK(status_.ok());
status_ = grpc::Status(grpc::StatusCode::UNKNOWN, "");
return std::move(data_).value();
}
// Sets the data.
void emplace(T&& data) {
status_ = grpc::Status::OK;
data_.emplace(std::move(data));
}
std::string ToString() const { return GrpcStatusToString(status()); }
private:
grpc::Status status_;
std::optional<T> data_;
};
} // namespace utils
} // namespace cast
#endif // CHROMECAST_CAST_CORE_GRPC_GRPC_STATUS_OR_H_