mirror of
https://github.com/kidfromjupiter/nearby.git
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Alexey Polyudov
2155b3ddeb
Signed-off-by: Alexey Polyudov <apolyudov@google.com> Change-Id: I9850950db8bd84f0904ea1a413151887f52098cf
99 lines
3.1 KiB
C++
99 lines
3.1 KiB
C++
#ifndef PLATFORM_BASE_EXCEPTION_H_
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#define PLATFORM_BASE_EXCEPTION_H_
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#include <utility>
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#include "absl/meta/type_traits.h"
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namespace location {
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namespace nearby {
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struct Exception {
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enum Value : int {
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kFailed = -1, // Initial value of Exception; any unknown error.
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kSuccess = 0, // No exception.
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kIo = 1, // IO Error happened.
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kInterrupted = 2, // Operation was interrupted.
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kInvalidProtocolBuffer = 3, // Couldn't parse.
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kExecution = 4, // Couldn't execute.
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kTimeout = 5, // Operarion did not finish within specified time.
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};
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bool Ok() const { return value == kSuccess; }
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bool Raised() const { return !Ok(); }
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bool Raised(Value value) const { return this->value == value; }
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Value value{kFailed};
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};
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constexpr inline bool operator==(const Exception& a, const Exception& b) {
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return a.value == b.value;
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}
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constexpr inline bool operator!=(const Exception& a, const Exception& b) {
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return !(a == b);
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}
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// ExceptionOr provides experience similar to StatusOr<T> used in
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// Google Cloud API, see:
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// https://googleapis.github.io/google-cloud-cpp/0.7.0/common/status__or_8h_source.html
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//
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// If ok() returns true, result() is a usable return value. Otherwise,
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// exception() explains why such a value is not present.
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//
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// A typical pattern of usage is as follows:
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//
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// if (!e.ok()) {
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// if (Exception::EXCEPTION_TYPE_1 == e.exception()) {
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// // Handle Exception::EXCEPTION_TYPE_1.
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// } else if (Exception::EXCEPTION_TYPE_2 == e.exception()) {
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// // Handle Exception::EXCEPTION_TYPE_2.
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// }
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//
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// return;
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// }
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//
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// // Use e.result().
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template <typename T>
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class ExceptionOr {
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public:
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ExceptionOr() = default;
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explicit ExceptionOr(T&& result)
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: result_{std::move(result)},
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exception_{Exception::kSuccess} {} // NOLINT
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explicit ExceptionOr(const T& result)
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: result_{result}, exception_{Exception::kSuccess} {} // NOLINT
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ExceptionOr(Exception::Value exception) : exception_{exception} {} // NOLINT
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ExceptionOr(Exception exception) : exception_{exception} {} // NOLINT
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// If there exists explicit conversion from from U to T,
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// then allow explicit conversion from ExceptionOr<U> to ExceptionOr<T>.
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template <typename U, typename = absl::void_t<decltype(T{std::declval<U>()})>>
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explicit ExceptionOr<T>(ExceptionOr<U> value) {
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if (!value.ok()) {
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exception_ = value.GetException();
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} else {
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result_ = T{std::move(value.result())};
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exception_ = Exception{Exception::kSuccess};
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}
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}
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bool ok() const { return exception_.value == Exception::kSuccess; }
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T& result() & { return result_; }
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const T& result() const& { return result_; }
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T&& result() && { return std::move(result_); }
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const T&& result() const&& { return std::move(result_); }
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Exception::Value exception() const { return exception_.value; }
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T GetResult() const { return result_; }
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Exception GetException() const { return exception_; }
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private:
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T result_{};
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Exception exception_{Exception::kFailed};
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};
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} // namespace nearby
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} // namespace location
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#endif // PLATFORM_BASE_EXCEPTION_H_
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