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tvl-depot/third_party/abseil_cpp/absl/status/statusor.h
Vincent Ambo 082c006c04 merge(3p/absl): subtree merge of Abseil up to e19260f 
... notably, this includes Abseil's own StatusOr type, which
conflicted with our implementation (that was taken from TensorFlow).

Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f
2020-11-21 15:48:57 +01:00

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// Copyright 2020 The Abseil Authors.
//
// 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
//
// https://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.
//
// -----------------------------------------------------------------------------
// File: statusor.h
// -----------------------------------------------------------------------------
//
// An `absl::StatusOr<T>` represents a union of an `absl::Status` object
// and an object of type `T`. The `absl::StatusOr<T>` will either contain an
// object of type `T` (indicating a successful operation), or an error (of type
// `absl::Status`) explaining why such a value is not present.
//
// In general, check the success of an operation returning an
// `absl::StatusOr<T>` like you would an `absl::Status` by using the `ok()`
// member function.
//
// Example:
//
// StatusOr<Foo> result = Calculation();
// if (result.ok()) {
// result->DoSomethingCool();
// } else {
// LOG(ERROR) << result.status();
// }
#ifndef ABSL_STATUS_STATUSOR_H_
#define ABSL_STATUS_STATUSOR_H_
#include <exception>
#include <initializer_list>
#include <new>
#include <string>
#include <type_traits>
#include <utility>
#include "absl/base/attributes.h"
#include "absl/meta/type_traits.h"
#include "absl/status/internal/statusor_internal.h"
#include "absl/status/status.h"
#include "absl/types/variant.h"
#include "absl/utility/utility.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
// BadStatusOrAccess
//
// This class defines the type of object to throw (if exceptions are enabled),
// when accessing the value of an `absl::StatusOr<T>` object that does not
// contain a value. This behavior is analogous to that of
// `std::bad_optional_access` in the case of accessing an invalid
// `std::optional` value.
//
// Example:
//
// try {
// absl::StatusOr<int> v = FetchInt();
// DoWork(v.value()); // Accessing value() when not "OK" may throw
// } catch (absl::BadStatusOrAccess& ex) {
// LOG(ERROR) << ex.status();
// }
class BadStatusOrAccess : public std::exception {
public:
explicit BadStatusOrAccess(absl::Status status);
~BadStatusOrAccess() override;
// BadStatusOrAccess::what()
//
// Returns the associated explanatory string of the `absl::StatusOr<T>`
// object's error code. This function only returns the string literal "Bad
// StatusOr Access" for cases when evaluating general exceptions.
//
// The pointer of this string is guaranteed to be valid until any non-const
// function is invoked on the exception object.
const char* what() const noexcept override;
// BadStatusOrAccess::status()
//
// Returns the associated `absl::Status` of the `absl::StatusOr<T>` object's
// error.
const absl::Status& status() const;
private:
absl::Status status_;
};
// Returned StatusOr objects may not be ignored.
template <typename T>
class ABSL_MUST_USE_RESULT StatusOr;
// absl::StatusOr<T>
//
// The `absl::StatusOr<T>` class template is a union of an `absl::Status` object
// and an object of type `T`. The `absl::StatusOr<T>` models an object that is
// either a usable object, or an error (of type `absl::Status`) explaining why
// such an object is not present. An `absl::StatusOr<T>` is typically the return
// value of a function which may fail.
//
// An `absl::StatusOr<T>` can never hold an "OK" status (an
// `absl::StatusCode::kOk` value); instead, the presence of an object of type
// `T` indicates success. Instead of checking for a `kOk` value, use the
// `absl::StatusOr<T>::ok()` member function. (It is for this reason, and code
// readability, that using the `ok()` function is preferred for `absl::Status`
// as well.)
//
// Example:
//
// StatusOr<Foo> result = DoBigCalculationThatCouldFail();
// if (result.ok()) {
// result->DoSomethingCool();
// } else {
// LOG(ERROR) << result.status();
// }
//
// Accessing the object held by an `absl::StatusOr<T>` should be performed via
// `operator*` or `operator->`, after a call to `ok()` confirms that the
// `absl::StatusOr<T>` holds an object of type `T`:
//
// Example:
//
// absl::StatusOr<int> i = GetCount();
// if (i.ok()) {
// updated_total += *i
// }
//
// NOTE: using `absl::StatusOr<T>::value()` when no valid value is present will
// throw an exception if exceptions are enabled or terminate the process when
// execeptions are not enabled.
//
// Example:
//
// StatusOr<Foo> result = DoBigCalculationThatCouldFail();
// const Foo& foo = result.value(); // Crash/exception if no value present
// foo.DoSomethingCool();
//
// A `absl::StatusOr<T*>` can be constructed from a null pointer like any other
// pointer value, and the result will be that `ok()` returns `true` and
// `value()` returns `nullptr`. Checking the value of pointer in an
// `absl::StatusOr<T>` generally requires a bit more care, to ensure both that a
// value is present and that value is not null:
//
// StatusOr<std::unique_ptr<Foo>> result = FooFactory::MakeNewFoo(arg);
// if (!result.ok()) {
// LOG(ERROR) << result.status();
// } else if (*result == nullptr) {
// LOG(ERROR) << "Unexpected null pointer";
// } else {
// (*result)->DoSomethingCool();
// }
//
// Example factory implementation returning StatusOr<T>:
//
// StatusOr<Foo> FooFactory::MakeFoo(int arg) {
// if (arg <= 0) {
// return absl::Status(absl::StatusCode::kInvalidArgument,
// "Arg must be positive");
// }
// return Foo(arg);
// }
template <typename T>
class StatusOr : private internal_statusor::StatusOrData<T>,
private internal_statusor::CopyCtorBase<T>,
private internal_statusor::MoveCtorBase<T>,
private internal_statusor::CopyAssignBase<T>,
private internal_statusor::MoveAssignBase<T> {
template <typename U>
friend class StatusOr;
typedef internal_statusor::StatusOrData<T> Base;
public:
// StatusOr<T>::value_type
//
// This instance data provides a generic `value_type` member for use within
// generic programming. This usage is analogous to that of
// `optional::value_type` in the case of `std::optional`.
typedef T value_type;
// Constructors
// Constructs a new `absl::StatusOr` with an `absl::StatusCode::kUnknown`
// status. This constructor is marked 'explicit' to prevent usages in return
// values such as 'return {};', under the misconception that
// `absl::StatusOr<std::vector<int>>` will be initialized with an empty
// vector, instead of an `absl::StatusCode::kUnknown` error code.
explicit StatusOr();
// `StatusOr<T>` is copy constructible if `T` is copy constructible.
StatusOr(const StatusOr&) = default;
// `StatusOr<T>` is copy assignable if `T` is copy constructible and copy
// assignable.
StatusOr& operator=(const StatusOr&) = default;
// `StatusOr<T>` is move constructible if `T` is move constructible.
StatusOr(StatusOr&&) = default;
// `StatusOr<T>` is moveAssignable if `T` is move constructible and move
// assignable.
StatusOr& operator=(StatusOr&&) = default;
// Converting Constructors
// Constructs a new `absl::StatusOr<T>` from an `absl::StatusOr<U>`, when `T`
// is constructible from `U`. To avoid ambiguity, these constructors are
// disabled if `T` is also constructible from `StatusOr<U>.`. This constructor
// is explicit if and only if the corresponding construction of `T` from `U`
// is explicit. (This constructor inherits its explicitness from the
// underlying constructor.)
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>,
std::is_constructible<T, const U&>,
std::is_convertible<const U&, T>,
absl::negation<
internal_statusor::IsConstructibleOrConvertibleFromStatusOr<
T, U>>>::value,
int> = 0>
StatusOr(const StatusOr<U>& other) // NOLINT
: Base(static_cast<const typename StatusOr<U>::Base&>(other)) {}
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>,
std::is_constructible<T, const U&>,
absl::negation<std::is_convertible<const U&, T>>,
absl::negation<
internal_statusor::IsConstructibleOrConvertibleFromStatusOr<
T, U>>>::value,
int> = 0>
explicit StatusOr(const StatusOr<U>& other)
: Base(static_cast<const typename StatusOr<U>::Base&>(other)) {}
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>, std::is_constructible<T, U&&>,
std::is_convertible<U&&, T>,
absl::negation<
internal_statusor::IsConstructibleOrConvertibleFromStatusOr<
T, U>>>::value,
int> = 0>
StatusOr(StatusOr<U>&& other) // NOLINT
: Base(static_cast<typename StatusOr<U>::Base&&>(other)) {}
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>, std::is_constructible<T, U&&>,
absl::negation<std::is_convertible<U&&, T>>,
absl::negation<
internal_statusor::IsConstructibleOrConvertibleFromStatusOr<
T, U>>>::value,
int> = 0>
explicit StatusOr(StatusOr<U>&& other)
: Base(static_cast<typename StatusOr<U>::Base&&>(other)) {}
// Converting Assignment Operators
// Creates an `absl::StatusOr<T>` through assignment from an
// `absl::StatusOr<U>` when:
//
// * Both `absl::StatusOr<T>` and `absl::StatusOr<U>` are OK by assigning
// `U` to `T` directly.
// * `absl::StatusOr<T>` is OK and `absl::StatusOr<U>` contains an error
// code by destroying `absl::StatusOr<T>`'s value and assigning from
// `absl::StatusOr<U>'
// * `absl::StatusOr<T>` contains an error code and `absl::StatusOr<U>` is
// OK by directly initializing `T` from `U`.
// * Both `absl::StatusOr<T>` and `absl::StatusOr<U>` contain an error
// code by assigning the `Status` in `absl::StatusOr<U>` to
// `absl::StatusOr<T>`
//
// These overloads only apply if `absl::StatusOr<T>` is constructible and
// assignable from `absl::StatusOr<U>` and `StatusOr<T>` cannot be directly
// assigned from `StatusOr<U>`.
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>,
std::is_constructible<T, const U&>,
std::is_assignable<T, const U&>,
absl::negation<
internal_statusor::
IsConstructibleOrConvertibleOrAssignableFromStatusOr<
T, U>>>::value,
int> = 0>
StatusOr& operator=(const StatusOr<U>& other) {
this->Assign(other);
return *this;
}
template <
typename U,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_same<T, U>>, std::is_constructible<T, U&&>,
std::is_assignable<T, U&&>,
absl::negation<
internal_statusor::
IsConstructibleOrConvertibleOrAssignableFromStatusOr<
T, U>>>::value,
int> = 0>
StatusOr& operator=(StatusOr<U>&& other) {
this->Assign(std::move(other));
return *this;
}
// Constructs a new `absl::StatusOr<T>` with a non-ok status. After calling
// this constructor, `this->ok()` will be `false` and calls to `value()` will
// crash, or produce an exception if exceptions are enabled.
//
// The constructor also takes any type `U` that is convertible to
// `absl::Status`. This constructor is explicit if an only if `U` is not of
// type `absl::Status` and the conversion from `U` to `Status` is explicit.
//
// REQUIRES: !Status(std::forward<U>(v)).ok(). This requirement is DCHECKed.
// In optimized builds, passing absl::OkStatus() here will have the effect
// of passing absl::StatusCode::kInternal as a fallback.
template <
typename U = absl::Status,
absl::enable_if_t<
absl::conjunction<
std::is_convertible<U&&, absl::Status>,
std::is_constructible<absl::Status, U&&>,
absl::negation<std::is_same<absl::decay_t<U>, absl::StatusOr<T>>>,
absl::negation<std::is_same<absl::decay_t<U>, T>>,
absl::negation<std::is_same<absl::decay_t<U>, absl::in_place_t>>,
absl::negation<internal_statusor::HasConversionOperatorToStatusOr<
T, U&&>>>::value,
int> = 0>
StatusOr(U&& v) : Base(std::forward<U>(v)) {}
template <
typename U = absl::Status,
absl::enable_if_t<
absl::conjunction<
absl::negation<std::is_convertible<U&&, absl::Status>>,
std::is_constructible<absl::Status, U&&>,
absl::negation<std::is_same<absl::decay_t<U>, absl::StatusOr<T>>>,
absl::negation<std::is_same<absl::decay_t<U>, T>>,
absl::negation<std::is_same<absl::decay_t<U>, absl::in_place_t>>,
absl::negation<internal_statusor::HasConversionOperatorToStatusOr<
T, U&&>>>::value,
int> = 0>
explicit StatusOr(U&& v) : Base(std::forward<U>(v)) {}
template <
typename U = absl::Status,
absl::enable_if_t<
absl::conjunction<
std::is_convertible<U&&, absl::Status>,
std::is_constructible<absl::Status, U&&>,
absl::negation<std::is_same<absl::decay_t<U>, absl::StatusOr<T>>>,
absl::negation<std::is_same<absl::decay_t<U>, T>>,
absl::negation<std::is_same<absl::decay_t<U>, absl::in_place_t>>,
absl::negation<internal_statusor::HasConversionOperatorToStatusOr<
T, U&&>>>::value,
int> = 0>
StatusOr& operator=(U&& v) {
this->AssignStatus(std::forward<U>(v));
return *this;
}
// Perfect-forwarding value assignment operator.
// If `*this` contains a `T` value before the call, the contained value is
// assigned from `std::forward<U>(v)`; Otherwise, it is directly-initialized
// from `std::forward<U>(v)`.
// This function does not participate in overload unless:
// 1. `std::is_constructible_v<T, U>` is true,
// 2. `std::is_assignable_v<T&, U>` is true.
// 3. `std::is_same_v<StatusOr<T>, std::remove_cvref_t<U>>` is false.
// 4. Assigning `U` to `T` is not ambiguous:
// If `U` is `StatusOr<V>` and `T` is constructible and assignable from
// both `StatusOr<V>` and `V`, the assignment is considered bug-prone and
// ambiguous thus will fail to compile. For example:
// StatusOr<bool> s1 = true; // s1.ok() && *s1 == true
// StatusOr<bool> s2 = false; // s2.ok() && *s2 == false
// s1 = s2; // ambiguous, `s1 = *s2` or `s1 = bool(s2)`?
template <
typename U = T,
typename = typename std::enable_if<absl::conjunction<
std::is_constructible<T, U&&>, std::is_assignable<T&, U&&>,
absl::disjunction<
std::is_same<absl::remove_cv_t<absl::remove_reference_t<U>>, T>,
absl::conjunction<
absl::negation<std::is_convertible<U&&, absl::Status>>,
absl::negation<internal_statusor::
HasConversionOperatorToStatusOr<T, U&&>>>>,
internal_statusor::IsForwardingAssignmentValid<T, U&&>>::value>::type>
StatusOr& operator=(U&& v) {
this->Assign(std::forward<U>(v));
return *this;
}
// Constructs the inner value `T` in-place using the provided args, using the
// `T(args...)` constructor.
template <typename... Args>
explicit StatusOr(absl::in_place_t, Args&&... args);
template <typename U, typename... Args>
explicit StatusOr(absl::in_place_t, std::initializer_list<U> ilist,
Args&&... args);
// Constructs the inner value `T` in-place using the provided args, using the
// `T(U)` (direct-initialization) constructor. This constructor is only valid
// if `T` can be constructed from a `U`. Can accept move or copy constructors.
//
// This constructor is explicit if `U` is not convertible to `T`. To avoid
// ambiguity, this constuctor is disabled if `U` is a `StatusOr<J>`, where `J`
// is convertible to `T`.
template <
typename U = T,
absl::enable_if_t<
absl::conjunction<
internal_statusor::IsDirectInitializationValid<T, U&&>,
std::is_constructible<T, U&&>, std::is_convertible<U&&, T>,
absl::disjunction<
std::is_same<absl::remove_cv_t<absl::remove_reference_t<U>>,
T>,
absl::conjunction<
absl::negation<std::is_convertible<U&&, absl::Status>>,
absl::negation<
internal_statusor::HasConversionOperatorToStatusOr<
T, U&&>>>>>::value,
int> = 0>
StatusOr(U&& u) // NOLINT
: StatusOr(absl::in_place, std::forward<U>(u)) {
}
template <
typename U = T,
absl::enable_if_t<
absl::conjunction<
internal_statusor::IsDirectInitializationValid<T, U&&>,
absl::disjunction<
std::is_same<absl::remove_cv_t<absl::remove_reference_t<U>>,
T>,
absl::conjunction<
absl::negation<std::is_constructible<absl::Status, U&&>>,
absl::negation<
internal_statusor::HasConversionOperatorToStatusOr<
T, U&&>>>>,
std::is_constructible<T, U&&>,
absl::negation<std::is_convertible<U&&, T>>>::value,
int> = 0>
explicit StatusOr(U&& u) // NOLINT
: StatusOr(absl::in_place, std::forward<U>(u)) {
}
// StatusOr<T>::ok()
//
// Returns whether or not this `absl::StatusOr<T>` holds a `T` value. This
// member function is analagous to `absl::Status::ok()` and should be used
// similarly to check the status of return values.
//
// Example:
//
// StatusOr<Foo> result = DoBigCalculationThatCouldFail();
// if (result.ok()) {
// // Handle result
// else {
// // Handle error
// }
ABSL_MUST_USE_RESULT bool ok() const { return this->status_.ok(); }
// StatusOr<T>::status()
//
// Returns a reference to the current `absl::Status` contained within the
// `absl::StatusOr<T>`. If `absl::StatusOr<T>` contains a `T`, then this
// function returns `absl::OkStatus()`.
const Status& status() const &;
Status status() &&;
// StatusOr<T>::value()
//
// Returns a reference to the held value if `this->ok()`. Otherwise, throws
// `absl::BadStatusOrAccess` if exceptions are enabled, or is guaranteed to
// terminate the process if exceptions are disabled.
//
// If you have already checked the status using `this->ok()`, you probably
// want to use `operator*()` or `operator->()` to access the value instead of
// `value`.
//
// Note: for value types that are cheap to copy, prefer simple code:
//
// T value = statusor.value();
//
// Otherwise, if the value type is expensive to copy, but can be left
// in the StatusOr, simply assign to a reference:
//
// T& value = statusor.value(); // or `const T&`
//
// Otherwise, if the value type supports an efficient move, it can be
// used as follows:
//
// T value = std::move(statusor).value();
//
// The `std::move` on statusor instead of on the whole expression enables
// warnings about possible uses of the statusor object after the move.
const T& value() const&;
T& value() &;
const T&& value() const&&;
T&& value() &&;
// StatusOr<T>:: operator*()
//
// Returns a reference to the current value.
//
// REQUIRES: `this->ok() == true`, otherwise the behavior is undefined.
//
// Use `this->ok()` to verify that there is a current value within the
// `absl::StatusOr<T>`. Alternatively, see the `value()` member function for a
// similar API that guarantees crashing or throwing an exception if there is
// no current value.
const T& operator*() const&;
T& operator*() &;
const T&& operator*() const&&;
T&& operator*() &&;
// StatusOr<T>::operator->()
//
// Returns a pointer to the current value.
//
// REQUIRES: `this->ok() == true`, otherwise the behavior is undefined.
//
// Use `this->ok()` to verify that there is a current value.
const T* operator->() const;
T* operator->();
// StatusOr<T>::value_or()
//
// Returns the current value if `this->ok() == true`. Otherwise constructs a
// value using the provided `default_value`.
//
// Unlike `value`, this function returns by value, copying the current value
// if necessary. If the value type supports an efficient move, it can be used
// as follows:
//
// T value = std::move(statusor).value_or(def);
//
// Unlike with `value`, calling `std::move()` on the result of `value_or` will
// still trigger a copy.
template <typename U>
T value_or(U&& default_value) const&;
template <typename U>
T value_or(U&& default_value) &&;
// StatusOr<T>::IgnoreError()
//
// Ignores any errors. This method does nothing except potentially suppress
// complaints from any tools that are checking that errors are not dropped on
// the floor.
void IgnoreError() const;
// StatusOr<T>::emplace()
//
// Reconstructs the inner value T in-place using the provided args, using the
// T(args...) constructor. Returns reference to the reconstructed `T`.
template <typename... Args>
T& emplace(Args&&... args) {
if (ok()) {
this->Clear();
this->MakeValue(std::forward<Args>(args)...);
} else {
this->MakeValue(std::forward<Args>(args)...);
this->status_ = absl::OkStatus();
}
return this->data_;
}
template <
typename U, typename... Args,
absl::enable_if_t<
std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value,
int> = 0>
T& emplace(std::initializer_list<U> ilist, Args&&... args) {
if (ok()) {
this->Clear();
this->MakeValue(ilist, std::forward<Args>(args)...);
} else {
this->MakeValue(ilist, std::forward<Args>(args)...);
this->status_ = absl::OkStatus();
}
return this->data_;
}
private:
using internal_statusor::StatusOrData<T>::Assign;
template <typename U>
void Assign(const absl::StatusOr<U>& other);
template <typename U>
void Assign(absl::StatusOr<U>&& other);
};
// operator==()
//
// This operator checks the equality of two `absl::StatusOr<T>` objects.
template <typename T>
bool operator==(const StatusOr<T>& lhs, const StatusOr<T>& rhs) {
if (lhs.ok() && rhs.ok()) return *lhs == *rhs;
return lhs.status() == rhs.status();
}
// operator!=()
//
// This operator checks the inequality of two `absl::StatusOr<T>` objects.
template <typename T>
bool operator!=(const StatusOr<T>& lhs, const StatusOr<T>& rhs) {
return !(lhs == rhs);
}
//------------------------------------------------------------------------------
// Implementation details for StatusOr<T>
//------------------------------------------------------------------------------
// TODO(sbenza): avoid the string here completely.
template <typename T>
StatusOr<T>::StatusOr() : Base(Status(absl::StatusCode::kUnknown, "")) {}
template <typename T>
template <typename U>
inline void StatusOr<T>::Assign(const StatusOr<U>& other) {
if (other.ok()) {
this->Assign(*other);
} else {
this->AssignStatus(other.status());
}
}
template <typename T>
template <typename U>
inline void StatusOr<T>::Assign(StatusOr<U>&& other) {
if (other.ok()) {
this->Assign(*std::move(other));
} else {
this->AssignStatus(std::move(other).status());
}
}
template <typename T>
template <typename... Args>
StatusOr<T>::StatusOr(absl::in_place_t, Args&&... args)
: Base(absl::in_place, std::forward<Args>(args)...) {}
template <typename T>
template <typename U, typename... Args>
StatusOr<T>::StatusOr(absl::in_place_t, std::initializer_list<U> ilist,
Args&&... args)
: Base(absl::in_place, ilist, std::forward<Args>(args)...) {}
template <typename T>
const Status& StatusOr<T>::status() const & { return this->status_; }
template <typename T>
Status StatusOr<T>::status() && {
return ok() ? OkStatus() : std::move(this->status_);
}
template <typename T>
const T& StatusOr<T>::value() const& {
if (!this->ok()) internal_statusor::ThrowBadStatusOrAccess(this->status_);
return this->data_;
}
template <typename T>
T& StatusOr<T>::value() & {
if (!this->ok()) internal_statusor::ThrowBadStatusOrAccess(this->status_);
return this->data_;
}
template <typename T>
const T&& StatusOr<T>::value() const&& {
if (!this->ok()) {
internal_statusor::ThrowBadStatusOrAccess(std::move(this->status_));
}
return std::move(this->data_);
}
template <typename T>
T&& StatusOr<T>::value() && {
if (!this->ok()) {
internal_statusor::ThrowBadStatusOrAccess(std::move(this->status_));
}
return std::move(this->data_);
}
template <typename T>
const T& StatusOr<T>::operator*() const& {
this->EnsureOk();
return this->data_;
}
template <typename T>
T& StatusOr<T>::operator*() & {
this->EnsureOk();
return this->data_;
}
template <typename T>
const T&& StatusOr<T>::operator*() const&& {
this->EnsureOk();
return std::move(this->data_);
}
template <typename T>
T&& StatusOr<T>::operator*() && {
this->EnsureOk();
return std::move(this->data_);
}
template <typename T>
const T* StatusOr<T>::operator->() const {
this->EnsureOk();
return &this->data_;
}
template <typename T>
T* StatusOr<T>::operator->() {
this->EnsureOk();
return &this->data_;
}
template <typename T>
template <typename U>
T StatusOr<T>::value_or(U&& default_value) const& {
if (ok()) {
return this->data_;
}
return std::forward<U>(default_value);
}
template <typename T>
template <typename U>
T StatusOr<T>::value_or(U&& default_value) && {
if (ok()) {
return std::move(this->data_);
}
return std::forward<U>(default_value);
}
template <typename T>
void StatusOr<T>::IgnoreError() const {
// no-op
}
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_STATUS_STATUSOR_H_
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