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merge(3p/absl): subtree merge of Abseil up to e19260f

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... notably, this includes Abseil's own StatusOr type, which
conflicted with our implementation (that was taken from TensorFlow).

Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f
This commit is contained in:
Vincent Ambo 2020-11-21 14:43:54 +01:00
parent cc27324d02
commit 082c006c04
854 changed files with 11260 additions and 5296 deletions
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858
third_party/abseil_cpp/absl/status/statusor.h vendored
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@ -1,333 +1,700 @@
/* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
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.
==============================================================================*/
// StatusOr<T> is the union of a Status object and a T object. StatusOr models
// the concept of an object that is either a value, or an error Status
// explaining why such a value is not present. To this end, StatusOr<T> does not
// allow its Status value to be StatusCode::kOk.
// Copyright 2020 The Abseil Authors.
//
// The primary use-case for StatusOr<T> is as the return value of a
// function which may fail.
// 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
//
// Example client usage for a StatusOr<T>, where T is not a pointer:
// https://www.apache.org/licenses/LICENSE-2.0
//
// StatusOr<float> result = DoBigCalculationThatCouldFail();
// if (result.ok()) {
// float answer = result.ValueOrDie();
// printf("Big calculation yielded: %f", answer);
// } else {
// LOG(ERROR) << result.status();
// }
// 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.
//
// Example client usage for a StatusOr<T*>:
// -----------------------------------------------------------------------------
// File: statusor.h
// -----------------------------------------------------------------------------
//
// StatusOr<Foo*> result = FooFactory::MakeNewFoo(arg);
// if (result.ok()) {
// std::unique_ptr<Foo> foo(result.ValueOrDie());
// foo->DoSomethingCool();
// } else {
// LOG(ERROR) << result.status();
// }
// 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.
//
// Example client usage for a StatusOr<std::unique_ptr<T>>:
// 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.
//
// StatusOr<std::unique_ptr<Foo>> result = FooFactory::MakeNewFoo(arg);
// if (result.ok()) {
// std::unique_ptr<Foo> foo = std::move(result.ValueOrDie());
// foo->DoSomethingCool();
// } else {
// LOG(ERROR) << result.status();
// }
// Example:
//
// Example factory implementation returning StatusOr<T*>:
//
// StatusOr<Foo*> FooFactory::MakeNewFoo(int arg) {
// if (arg <= 0) {
// return absl::InvalidArgumentError("Arg must be positive");
// } else {
// return new Foo(arg);
// }
// }
//
// Note that the assignment operators require that destroying the currently
// stored value cannot invalidate the argument; in other words, the argument
// cannot be an alias for the current value, or anything owned by the current
// value.
// 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/status/statusor_internals.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::TraitsBase<
std::is_copy_constructible<T>::value,
std::is_move_constructible<T>::value> {
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:
typedef T element_type; // DEPRECATED: use `value_type`.
// 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;
// Constructs a new StatusOr with Status::UNKNOWN status. This is marked
// 'explicit' to try to catch cases like 'return {};', where people think
// StatusOr<std::vector<int>> will be initialized with an empty vector,
// instead of a Status::UNKNOWN status.
// 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> will be copy constructible/assignable if T is copy
// constructible.
// `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> will be move constructible/assignable if T is move
// constructible.
// `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;
// Conversion copy/move constructor, T must be convertible from U.
template <typename U, typename std::enable_if<
std::is_convertible<U, T>::value>::type* = nullptr>
StatusOr(const StatusOr<U>& other);
template <typename U, typename std::enable_if<
std::is_convertible<U, T>::value>::type* = nullptr>
StatusOr(StatusOr<U>&& other);
// Converting Constructors
// Conversion copy/move assignment operator, T must be convertible from U.
template <typename U, typename std::enable_if<
std::is_convertible<U, T>::value>::type* = nullptr>
StatusOr& operator=(const StatusOr<U>& other);
template <typename U, typename std::enable_if<
std::is_convertible<U, T>::value>::type* = nullptr>
StatusOr& operator=(StatusOr<U>&& other);
// 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)) {}
// Constructs a new StatusOr with the given value. After calling this
// constructor, calls to ValueOrDie() will succeed, and calls to status() will
// return OK.
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:
//
// NOTE: Not explicit - we want to use StatusOr<T> as a return type
// so it is convenient and sensible to be able to do 'return T()'
// when the return type is StatusOr<T>.
// * 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>`
//
// REQUIRES: T is copy constructible.
StatusOr(const T& value);
// 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 StatusOr with the given non-ok status. After calling
// this constructor, calls to ValueOrDie() will CHECK-fail.
// 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.
//
// NOTE: Not explicit - we want to use StatusOr<T> as a return
// value, so it is convenient and sensible to be able to do 'return
// Status()' when the return type is StatusOr<T>.
// 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.ok(). This requirement is enforced with either an
// exception (the passed absl::Status) or a FATAL log.
StatusOr(const Status& status);
StatusOr& operator=(const Status& status);
// 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)) {}
// TODO(b/62186997): Add operator=(T) overloads.
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)) {}
// Similar to the `const T&` overload.
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.
//
// REQUIRES: T is move constructible.
StatusOr(T&& value);
// 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)) {
}
// RValue versions of the operations declared above.
StatusOr(Status&& status);
StatusOr& operator=(Status&& status);
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)) {
}
// Returns this->status().ok()
bool ok() const { return this->status_.ok(); }
// 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(); }
// Returns a reference to our status. If this contains a T, then
// returns OkStatus().
// 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() &&;
// Returns a reference to our current value, or CHECK-fails if !this->ok().
// 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.ValueOrDie();
// 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.ValueOrDie(); // or `const T&`
// 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).ValueOrDie();
// T value = std::move(statusor).value();
//
// The std::move on statusor instead of on the whole expression enables
// The `std::move` on statusor instead of on the whole expression enables
// warnings about possible uses of the statusor object after the move.
// C++ style guide waiver for ref-qualified overloads granted in cl/143176389
// See go/ref-qualifiers for more details on such overloads.
const T& ValueOrDie() const &;
T& ValueOrDie() &;
const T&& ValueOrDie() const &&;
T&& ValueOrDie() &&;
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.
// REQUIRES: `this->ok() == true`, otherwise the behavior is undefined.
//
// Use this->ok() or `operator bool()` to verify that there is a current
// value. Alternatively, see ValueOrDie() for a similar API that guarantees
// CHECK-failing if there is no current value.
// 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.
// REQUIRES: `this->ok() == true`, otherwise the behavior is undefined.
//
// Use this->ok() or `operator bool()` to verify that there is a current
// value.
// Use `this->ok()` to verify that there is a current value.
const T* operator->() const;
T* operator->();
T ConsumeValueOrDie() { return std::move(ValueOrDie()); }
// 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>
StatusOr<T>::StatusOr() : Base(Status(StatusCode::kUnknown, "")) {}
template <typename T>
StatusOr<T>::StatusOr(const T& value) : Base(value) {}
template <typename T>
StatusOr<T>::StatusOr(const Status& status) : Base(status) {}
template <typename T>
StatusOr<T>& StatusOr<T>::operator=(const Status& status) {
this->Assign(status);
return *this;
}
template <typename T>
StatusOr<T>::StatusOr(T&& value) : Base(std::move(value)) {}
template <typename T>
StatusOr<T>::StatusOr(Status&& status) : Base(std::move(status)) {}
template <typename T>
StatusOr<T>& StatusOr<T>::operator=(Status&& status) {
this->Assign(std::move(status));
return *this;
}
template <typename T>
template <typename U,
typename std::enable_if<std::is_convertible<U, T>::value>::type*>
inline StatusOr<T>::StatusOr(const StatusOr<U>& other)
: Base(static_cast<const typename StatusOr<U>::Base&>(other)) {}
template <typename T>
template <typename U,
typename std::enable_if<std::is_convertible<U, T>::value>::type*>
inline StatusOr<T>& StatusOr<T>::operator=(const StatusOr<U>& other) {
if (other.ok())
this->Assign(other.ValueOrDie());
else
this->Assign(other.status());
return *this;
}
template <typename T>
template <typename U,
typename std::enable_if<std::is_convertible<U, T>::value>::type*>
inline StatusOr<T>::StatusOr(StatusOr<U>&& other)
: Base(static_cast<typename StatusOr<U>::Base&&>(other)) {}
template <typename T>
template <typename U,
typename std::enable_if<std::is_convertible<U, T>::value>::type*>
inline StatusOr<T>& StatusOr<T>::operator=(StatusOr<U>&& other) {
template <typename U>
inline void StatusOr<T>::Assign(const StatusOr<U>& other) {
if (other.ok()) {
this->Assign(std::move(other).ValueOrDie());
this->Assign(*other);
} else {
this->Assign(std::move(other).status());
this->AssignStatus(other.status());
}
return *this;
}
template <typename T>
const Status& StatusOr<T>::status() const & {
return this->status_;
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() && {
// Note that we copy instead of moving the status here so that
// ~StatusOrData() can call ok() without invoking UB.
return ok() ? OkStatus() : this->status_;
return ok() ? OkStatus() : std::move(this->status_);
}
template <typename T>
const T& StatusOr<T>::ValueOrDie() const & {
this->EnsureOk();
const T& StatusOr<T>::value() const& {
if (!this->ok()) internal_statusor::ThrowBadStatusOrAccess(this->status_);
return this->data_;
}
template <typename T>
T& StatusOr<T>::ValueOrDie() & {
this->EnsureOk();
T& StatusOr<T>::value() & {
if (!this->ok()) internal_statusor::ThrowBadStatusOrAccess(this->status_);
return this->data_;
}
template <typename T>
const T&& StatusOr<T>::ValueOrDie() const && {
this->EnsureOk();
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>::ValueOrDie() && {
this->EnsureOk();
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();
@ -352,6 +719,36 @@ T&& StatusOr<T>::operator*() && {
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
@ -360,35 +757,4 @@ void StatusOr<T>::IgnoreError() const {
ABSL_NAMESPACE_END
} // namespace absl
#define ASSERT_OK_AND_ASSIGN(lhs, rexpr) \
ABSL_ASSERT_OK_AND_ASSIGN_IMPL( \
ABSL_STATUS_MACROS_CONCAT_NAME(_status_or_value, __COUNTER__), lhs, \
rexpr);
#define ABSL_ASSERT_OK_AND_ASSIGN_IMPL(statusor, lhs, rexpr) \
auto statusor = (rexpr); \
ASSERT_TRUE(statusor.status().ok()) << statusor.status(); \
lhs = std::move(statusor.ValueOrDie())
#define ABSL_STATUS_MACROS_CONCAT_NAME(x, y) ABSL_STATUS_MACROS_CONCAT_IMPL(x, y)
#define ABSL_STATUS_MACROS_CONCAT_IMPL(x, y) x##y
#define ASSIGN_OR_RETURN(lhs, rexpr) \
ABSL_ASSIGN_OR_RETURN_IMPL( \
ABSL_STATUS_MACROS_CONCAT_NAME(_status_or_value, __COUNTER__), lhs, rexpr)
#define ABSL_ASSIGN_OR_RETURN_IMPL(statusor, lhs, rexpr) \
auto statusor = (rexpr); \
if (ABSL_PREDICT_FALSE(!statusor.ok())) { \
return statusor.status(); \
} \
lhs = std::move(statusor.ValueOrDie())
#define RETURN_IF_ERROR(status) \
do { \
if (ABSL_PREDICT_FALSE(!status.ok())) { \
return status; \
} \
} while(0)
#endif // ABSL_STATUS_STATUSOR_H_