Reimplement pdfium::Optional with absl::optional.
Now that abseil is available, replace pdfium::Optional with
absl::optional. third_party/base/optional.h continues to exist for now
to help bridge the transition.
Bug: pdfium:1726
Change-Id: Ie5b28493837892cb1895c36a3568a5dcd981a85b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/85514
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/third_party/base/optional.h b/third_party/base/optional.h
index a380d4e..f308335 100644
--- a/third_party/base/optional.h
+++ b/third_party/base/optional.h
@@ -5,954 +5,17 @@
#ifndef THIRD_PARTY_BASE_OPTIONAL_H_
#define THIRD_PARTY_BASE_OPTIONAL_H_
-#include <functional>
-#include <type_traits>
-#include <utility>
-
-#include "third_party/base/check.h"
-#include "third_party/base/template_util.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
namespace pdfium {
-// Specification:
-// http://en.cppreference.com/w/cpp/utility/optional/nullopt_t
-struct nullopt_t {
- constexpr explicit nullopt_t(int) {}
-};
-
-// Specification:
-// http://en.cppreference.com/w/cpp/utility/optional/nullopt
-constexpr nullopt_t nullopt(0);
-
-// Forward declaration, which is refered by following helpers.
-template <typename T>
-class Optional;
-
-namespace internal {
-
-struct DummyUnionMember {};
-
-template <typename T, bool = std::is_trivially_destructible<T>::value>
-struct OptionalStorageBase {
- // Provide non-defaulted default ctor to make sure it's not deleted by
- // non-trivial T::T() in the union.
- constexpr OptionalStorageBase() : dummy_() {}
-
- template <class... Args>
- constexpr explicit OptionalStorageBase(in_place_t, Args&&... args)
- : is_populated_(true), value_(std::forward<Args>(args)...) {}
-
- // When T is not trivially destructible we must call its
- // destructor before deallocating its memory.
- // Note that this hides the (implicitly declared) move constructor, which
- // would be used for constexpr move constructor in OptionalStorage<T>.
- // It is needed iff T is trivially move constructible. However, the current
- // is_trivially_{copy,move}_constructible implementation requires
- // is_trivially_destructible (which looks a bug, cf:
- // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51452 and
- // http://cplusplus.github.io/LWG/lwg-active.html#2116), so it is not
- // necessary for this case at the moment. Please see also the destructor
- // comment in "is_trivially_destructible = true" specialization below.
- ~OptionalStorageBase() {
- if (is_populated_)
- value_.~T();
- }
-
- template <class... Args>
- void Init(Args&&... args) {
- DCHECK(!is_populated_);
- ::new (&value_) T(std::forward<Args>(args)...);
- is_populated_ = true;
- }
-
- bool is_populated_ = false;
- union {
- // |dummy_| exists so that the union will always be initialized, even when
- // it doesn't contain a value. Union members must be initialized for the
- // constructor to be 'constexpr'. Having a special trivial class for it is
- // better than e.g. using char, because the latter will have to be
- // zero-initialized, and the compiler can't optimize this write away, since
- // it assumes this might be a programmer's invariant. This can also cause
- // problems for conservative GC in Oilpan. Compiler is free to split shared
- // and non-shared parts of the union in separate memory locations (or
- // registers). If conservative GC is triggered at this moment, the stack
- // scanning routine won't find the correct object pointed from
- // Optional<HeapObject*>. This dummy valueless struct lets the compiler know
- // that we don't care about the value of this union member.
- DummyUnionMember dummy_;
- T value_;
- };
-};
-
-template <typename T>
-struct OptionalStorageBase<T, true /* trivially destructible */> {
- // Provide non-defaulted default ctor to make sure it's not deleted by
- // non-trivial T::T() in the union.
- constexpr OptionalStorageBase() : dummy_() {}
-
- template <class... Args>
- constexpr explicit OptionalStorageBase(in_place_t, Args&&... args)
- : is_populated_(true), value_(std::forward<Args>(args)...) {}
-
- // When T is trivially destructible (i.e. its destructor does nothing) there
- // is no need to call it. Implicitly defined destructor is trivial, because
- // both members (bool and union containing only variants which are trivially
- // destructible) are trivially destructible.
- // Explicitly-defaulted destructor is also trivial, but do not use it here,
- // because it hides the implicit move constructor. It is needed to implement
- // constexpr move constructor in OptionalStorage iff T is trivially move
- // constructible. Note that, if T is trivially move constructible, the move
- // constructor of OptionalStorageBase<T> is also implicitly defined and it is
- // trivially move constructor. If T is not trivially move constructible,
- // "not declaring move constructor without destructor declaration" here means
- // "delete move constructor", which works because any move constructor of
- // OptionalStorage will not refer to it in that case.
-
- template <class... Args>
- void Init(Args&&... args) {
- DCHECK(!is_populated_);
- ::new (&value_) T(std::forward<Args>(args)...);
- is_populated_ = true;
- }
-
- bool is_populated_ = false;
- union {
- // |dummy_| exists so that the union will always be initialized, even when
- // it doesn't contain a value. Union members must be initialized for the
- // constructor to be 'constexpr'. Having a special trivial class for it is
- // better than e.g. using char, because the latter will have to be
- // zero-initialized, and the compiler can't optimize this write away, since
- // it assumes this might be a programmer's invariant. This can also cause
- // problems for conservative GC in Oilpan. Compiler is free to split shared
- // and non-shared parts of the union in separate memory locations (or
- // registers). If conservative GC is triggered at this moment, the stack
- // scanning routine won't find the correct object pointed from
- // Optional<HeapObject*>. This dummy valueless struct lets the compiler know
- // that we don't care about the value of this union member.
- DummyUnionMember dummy_;
- T value_;
- };
-};
-
-// Implement conditional constexpr copy and move constructors. These are
-// constexpr if is_trivially_{copy,move}_constructible<T>::value is true
-// respectively. If each is true, the corresponding constructor is defined as
-// "= default;", which generates a constexpr constructor (In this case,
-// the condition of constexpr-ness is satisfied because the base class also has
-// compiler generated constexpr {copy,move} constructors). Note that
-// placement-new is prohibited in constexpr.
-template <typename T,
- bool = is_trivially_copy_constructible<T>::value,
- bool = std::is_trivially_move_constructible<T>::value>
-struct OptionalStorage : OptionalStorageBase<T> {
- // This is no trivially {copy,move} constructible case. Other cases are
- // defined below as specializations.
-
- // Accessing the members of template base class requires explicit
- // declaration.
- using OptionalStorageBase<T>::is_populated_;
- using OptionalStorageBase<T>::value_;
- using OptionalStorageBase<T>::Init;
-
- // Inherit constructors (specifically, the in_place constructor).
- using OptionalStorageBase<T>::OptionalStorageBase;
-
- // User defined constructor deletes the default constructor.
- // Define it explicitly.
- OptionalStorage() = default;
-
- OptionalStorage(const OptionalStorage& other) {
- if (other.is_populated_)
- Init(other.value_);
- }
-
- OptionalStorage(OptionalStorage&& other) noexcept(
- std::is_nothrow_move_constructible<T>::value) {
- if (other.is_populated_)
- Init(std::move(other.value_));
- }
-};
-
-template <typename T>
-struct OptionalStorage<T,
- true /* trivially copy constructible */,
- false /* trivially move constructible */>
- : OptionalStorageBase<T> {
- using OptionalStorageBase<T>::is_populated_;
- using OptionalStorageBase<T>::value_;
- using OptionalStorageBase<T>::Init;
- using OptionalStorageBase<T>::OptionalStorageBase;
-
- OptionalStorage() = default;
- OptionalStorage(const OptionalStorage& other) = default;
-
- OptionalStorage(OptionalStorage&& other) noexcept(
- std::is_nothrow_move_constructible<T>::value) {
- if (other.is_populated_)
- Init(std::move(other.value_));
- }
-};
-
-template <typename T>
-struct OptionalStorage<T,
- false /* trivially copy constructible */,
- true /* trivially move constructible */>
- : OptionalStorageBase<T> {
- using OptionalStorageBase<T>::is_populated_;
- using OptionalStorageBase<T>::value_;
- using OptionalStorageBase<T>::Init;
- using OptionalStorageBase<T>::OptionalStorageBase;
-
- OptionalStorage() = default;
- OptionalStorage(OptionalStorage&& other) = default;
-
- OptionalStorage(const OptionalStorage& other) {
- if (other.is_populated_)
- Init(other.value_);
- }
-};
-
-template <typename T>
-struct OptionalStorage<T,
- true /* trivially copy constructible */,
- true /* trivially move constructible */>
- : OptionalStorageBase<T> {
- // If both trivially {copy,move} constructible are true, it is not necessary
- // to use user-defined constructors. So, just inheriting constructors
- // from the base class works.
- using OptionalStorageBase<T>::OptionalStorageBase;
-};
-
-// Base class to support conditionally usable copy-/move- constructors
-// and assign operators.
-template <typename T>
-class OptionalBase {
- // This class provides implementation rather than public API, so everything
- // should be hidden. Often we use composition, but we cannot in this case
- // because of C++ language restriction.
- protected:
- constexpr OptionalBase() = default;
- constexpr OptionalBase(const OptionalBase& other) = default;
- constexpr OptionalBase(OptionalBase&& other) = default;
-
- template <class... Args>
- constexpr explicit OptionalBase(in_place_t, Args&&... args)
- : storage_(in_place, std::forward<Args>(args)...) {}
-
- // Implementation of converting constructors.
- template <typename U>
- explicit OptionalBase(const OptionalBase<U>& other) {
- if (other.storage_.is_populated_)
- storage_.Init(other.storage_.value_);
- }
-
- template <typename U>
- explicit OptionalBase(OptionalBase<U>&& other) {
- if (other.storage_.is_populated_)
- storage_.Init(std::move(other.storage_.value_));
- }
-
- ~OptionalBase() = default;
-
- OptionalBase& operator=(const OptionalBase& other) {
- CopyAssign(other);
- return *this;
- }
-
- OptionalBase& operator=(OptionalBase&& other) noexcept(
- std::is_nothrow_move_assignable<T>::value&&
- std::is_nothrow_move_constructible<T>::value) {
- MoveAssign(std::move(other));
- return *this;
- }
-
- template <typename U>
- void CopyAssign(const OptionalBase<U>& other) {
- if (other.storage_.is_populated_)
- InitOrAssign(other.storage_.value_);
- else
- FreeIfNeeded();
- }
-
- template <typename U>
- void MoveAssign(OptionalBase<U>&& other) {
- if (other.storage_.is_populated_)
- InitOrAssign(std::move(other.storage_.value_));
- else
- FreeIfNeeded();
- }
-
- template <typename U>
- void InitOrAssign(U&& value) {
- if (storage_.is_populated_)
- storage_.value_ = std::forward<U>(value);
- else
- storage_.Init(std::forward<U>(value));
- }
-
- void FreeIfNeeded() {
- if (!storage_.is_populated_)
- return;
- storage_.value_.~T();
- storage_.is_populated_ = false;
- }
-
- // For implementing conversion, allow access to other typed OptionalBase
- // class.
- template <typename U>
- friend class OptionalBase;
-
- OptionalStorage<T> storage_;
-};
-
-// The following {Copy,Move}{Constructible,Assignable} structs are helpers to
-// implement constructor/assign-operator overloading. Specifically, if T is
-// is not movable but copyable, Optional<T>'s move constructor should not
-// participate in overload resolution. This inheritance trick implements that.
-template <bool is_copy_constructible>
-struct CopyConstructible {};
-
-template <>
-struct CopyConstructible<false> {
- constexpr CopyConstructible() = default;
- constexpr CopyConstructible(const CopyConstructible&) = delete;
- constexpr CopyConstructible(CopyConstructible&&) = default;
- CopyConstructible& operator=(const CopyConstructible&) = default;
- CopyConstructible& operator=(CopyConstructible&&) = default;
-};
-
-template <bool is_move_constructible>
-struct MoveConstructible {};
-
-template <>
-struct MoveConstructible<false> {
- constexpr MoveConstructible() = default;
- constexpr MoveConstructible(const MoveConstructible&) = default;
- constexpr MoveConstructible(MoveConstructible&&) = delete;
- MoveConstructible& operator=(const MoveConstructible&) = default;
- MoveConstructible& operator=(MoveConstructible&&) = default;
-};
-
-template <bool is_copy_assignable>
-struct CopyAssignable {};
-
-template <>
-struct CopyAssignable<false> {
- constexpr CopyAssignable() = default;
- constexpr CopyAssignable(const CopyAssignable&) = default;
- constexpr CopyAssignable(CopyAssignable&&) = default;
- CopyAssignable& operator=(const CopyAssignable&) = delete;
- CopyAssignable& operator=(CopyAssignable&&) = default;
-};
-
-template <bool is_move_assignable>
-struct MoveAssignable {};
-
-template <>
-struct MoveAssignable<false> {
- constexpr MoveAssignable() = default;
- constexpr MoveAssignable(const MoveAssignable&) = default;
- constexpr MoveAssignable(MoveAssignable&&) = default;
- MoveAssignable& operator=(const MoveAssignable&) = default;
- MoveAssignable& operator=(MoveAssignable&&) = delete;
-};
-
-// Helper to conditionally enable converting constructors and assign operators.
-template <typename T, typename U>
-using IsConvertibleFromOptional =
- disjunction<std::is_constructible<T, Optional<U>&>,
- std::is_constructible<T, const Optional<U>&>,
- std::is_constructible<T, Optional<U>&&>,
- std::is_constructible<T, const Optional<U>&&>,
- std::is_convertible<Optional<U>&, T>,
- std::is_convertible<const Optional<U>&, T>,
- std::is_convertible<Optional<U>&&, T>,
- std::is_convertible<const Optional<U>&&, T>>;
-
-template <typename T, typename U>
-using IsAssignableFromOptional =
- disjunction<IsConvertibleFromOptional<T, U>,
- std::is_assignable<T&, Optional<U>&>,
- std::is_assignable<T&, const Optional<U>&>,
- std::is_assignable<T&, Optional<U>&&>,
- std::is_assignable<T&, const Optional<U>&&>>;
-
-// Forward compatibility for C++17.
-// Introduce one more deeper nested namespace to avoid leaking using std::swap.
-namespace swappable_impl {
-using std::swap;
-
-struct IsSwappableImpl {
- // Tests if swap can be called. Check<T&>(0) returns true_type iff swap
- // is available for T. Otherwise, Check's overload resolution falls back
- // to Check(...) declared below thanks to SFINAE, so returns false_type.
- template <typename T>
- static auto Check(int)
- -> decltype(swap(std::declval<T>(), std::declval<T>()), std::true_type());
-
- template <typename T>
- static std::false_type Check(...);
-};
-} // namespace swappable_impl
-
-template <typename T>
-struct IsSwappable : decltype(swappable_impl::IsSwappableImpl::Check<T&>(0)) {};
-
-// Forward compatibility for C++20.
-template <typename T>
-using RemoveCvRefT = std::remove_cv_t<std::remove_reference_t<T>>;
-
-} // namespace internal
-
-// On Windows, by default, empty-base class optimization does not work,
-// which means even if the base class is empty struct, it still consumes one
-// byte for its body. __declspec(empty_bases) enables the optimization.
-// cf)
-// https://blogs.msdn.microsoft.com/vcblog/2016/03/30/optimizing-the-layout-of-empty-base-classes-in-vs2015-update-2-3/
-#ifdef OS_WIN
-#define OPTIONAL_DECLSPEC_EMPTY_BASES __declspec(empty_bases)
-#else
-#define OPTIONAL_DECLSPEC_EMPTY_BASES
-#endif
-
-// pdfium::Optional is a PDFium version of the C++17 optional class:
-// std::optional documentation:
-// http://en.cppreference.com/w/cpp/utility/optional
-// Chromium documentation:
-// https://chromium.googlesource.com/chromium/src/+/main/docs/optional.md
-//
-// These are the differences between the specification and the implementation:
-// - Constructors do not use 'constexpr' as it is a C++14 extension.
-// - 'constexpr' might be missing in some places for reasons specified locally.
-// - No exceptions are thrown, because they are banned from PDFium.
-// Marked noexcept for only move constructor and move assign operators.
-// - All the non-members are in the 'pdfium' namespace instead of 'std'.
-//
-// Note that T cannot have a constructor T(Optional<T>) etc. Optional<T> checks
-// T's constructor (specifically via IsConvertibleFromOptional), and in the
-// check whether T can be constructible from Optional<T>, which is recursive
-// so it does not work. As of Feb 2018, std::optional C++17 implementation in
-// both clang and gcc has same limitation. MSVC SFINAE looks to have different
-// behavior, but anyway it reports an error, too.
-template <typename T>
-class OPTIONAL_DECLSPEC_EMPTY_BASES Optional
- : public internal::OptionalBase<T>,
- public internal::CopyConstructible<std::is_copy_constructible<T>::value>,
- public internal::MoveConstructible<std::is_move_constructible<T>::value>,
- public internal::CopyAssignable<std::is_copy_constructible<T>::value &&
- std::is_copy_assignable<T>::value>,
- public internal::MoveAssignable<std::is_move_constructible<T>::value &&
- std::is_move_assignable<T>::value> {
- private:
- // Disable some versions of T that are ill-formed.
- // See: https://timsong-cpp.github.io/cppwp/n4659/optional#syn-1
- static_assert(
- !std::is_same<internal::RemoveCvRefT<T>, in_place_t>::value,
- "instantiation of pdfium::Optional with in_place_t is ill-formed");
- static_assert(
- !std::is_same<internal::RemoveCvRefT<T>, nullopt_t>::value,
- "instantiation of pdfium::Optional with nullopt_t is ill-formed");
- static_assert(
- !std::is_reference<T>::value,
- "instantiation of pdfium::Optional with a reference type is ill-formed");
- // See: https://timsong-cpp.github.io/cppwp/n4659/optional#optional-3
- static_assert(
- std::is_destructible<T>::value,
- "instantiation of pdfium::Optional with a non-destructible type "
- "is ill-formed");
- // Arrays are explicitly disallowed because for arrays of known bound
- // is_destructible is of undefined value.
- // See: https://en.cppreference.com/w/cpp/types/is_destructible
- static_assert(
- !std::is_array<T>::value,
- "instantiation of pdfium::Optional with an array type is ill-formed");
-
- public:
-#undef OPTIONAL_DECLSPEC_EMPTY_BASES
- using value_type = T;
-
- // Defer default/copy/move constructor implementation to OptionalBase.
- constexpr Optional() = default;
- constexpr Optional(const Optional& other) = default;
- constexpr Optional(Optional&& other) noexcept(
- std::is_nothrow_move_constructible<T>::value) = default;
-
- constexpr Optional(nullopt_t) {} // NOLINT(runtime/explicit)
-
- // Converting copy constructor. "explicit" only if
- // std::is_convertible<const U&, T>::value is false. It is implemented by
- // declaring two almost same constructors, but that condition in enable_if_t
- // is different, so that either one is chosen, thanks to SFINAE.
- template <
- typename U,
- std::enable_if_t<std::is_constructible<T, const U&>::value &&
- !internal::IsConvertibleFromOptional<T, U>::value &&
- std::is_convertible<const U&, T>::value,
- bool> = false>
- Optional(const Optional<U>& other) : internal::OptionalBase<T>(other) {}
-
- template <
- typename U,
- std::enable_if_t<std::is_constructible<T, const U&>::value &&
- !internal::IsConvertibleFromOptional<T, U>::value &&
- !std::is_convertible<const U&, T>::value,
- bool> = false>
- explicit Optional(const Optional<U>& other)
- : internal::OptionalBase<T>(other) {}
-
- // Converting move constructor. Similar to converting copy constructor,
- // declaring two (explicit and non-explicit) constructors.
- template <
- typename U,
- std::enable_if_t<std::is_constructible<T, U&&>::value &&
- !internal::IsConvertibleFromOptional<T, U>::value &&
- std::is_convertible<U&&, T>::value,
- bool> = false>
- Optional(Optional<U>&& other) : internal::OptionalBase<T>(std::move(other)) {}
-
- template <
- typename U,
- std::enable_if_t<std::is_constructible<T, U&&>::value &&
- !internal::IsConvertibleFromOptional<T, U>::value &&
- !std::is_convertible<U&&, T>::value,
- bool> = false>
- explicit Optional(Optional<U>&& other)
- : internal::OptionalBase<T>(std::move(other)) {}
-
- template <class... Args>
- constexpr explicit Optional(in_place_t, Args&&... args)
- : internal::OptionalBase<T>(in_place, std::forward<Args>(args)...) {}
-
- template <
- class U,
- class... Args,
- class = std::enable_if_t<std::is_constructible<value_type,
- std::initializer_list<U>&,
- Args...>::value>>
- constexpr explicit Optional(in_place_t,
- std::initializer_list<U> il,
- Args&&... args)
- : internal::OptionalBase<T>(in_place, il, std::forward<Args>(args)...) {}
-
- // Forward value constructor. Similar to converting constructors,
- // conditionally explicit.
- template <
- typename U = value_type,
- std::enable_if_t<
- std::is_constructible<T, U&&>::value &&
- !std::is_same<internal::RemoveCvRefT<U>, in_place_t>::value &&
- !std::is_same<internal::RemoveCvRefT<U>, Optional<T>>::value &&
- std::is_convertible<U&&, T>::value,
- bool> = false>
- constexpr Optional(U&& value)
- : internal::OptionalBase<T>(in_place, std::forward<U>(value)) {}
-
- template <
- typename U = value_type,
- std::enable_if_t<
- std::is_constructible<T, U&&>::value &&
- !std::is_same<internal::RemoveCvRefT<U>, in_place_t>::value &&
- !std::is_same<internal::RemoveCvRefT<U>, Optional<T>>::value &&
- !std::is_convertible<U&&, T>::value,
- bool> = false>
- constexpr explicit Optional(U&& value)
- : internal::OptionalBase<T>(in_place, std::forward<U>(value)) {}
-
- ~Optional() = default;
-
- // Defer copy-/move- assign operator implementation to OptionalBase.
- Optional& operator=(const Optional& other) = default;
- Optional& operator=(Optional&& other) noexcept(
- std::is_nothrow_move_assignable<T>::value&&
- std::is_nothrow_move_constructible<T>::value) = default;
-
- Optional& operator=(nullopt_t) {
- FreeIfNeeded();
- return *this;
- }
-
- // Perfect-forwarded assignment.
- template <typename U>
- std::enable_if_t<
- !std::is_same<internal::RemoveCvRefT<U>, Optional<T>>::value &&
- std::is_constructible<T, U>::value &&
- std::is_assignable<T&, U>::value &&
- (!std::is_scalar<T>::value ||
- !std::is_same<std::decay_t<U>, T>::value),
- Optional&>
- operator=(U&& value) {
- InitOrAssign(std::forward<U>(value));
- return *this;
- }
-
- // Copy assign the state of other.
- template <typename U>
- std::enable_if_t<!internal::IsAssignableFromOptional<T, U>::value &&
- std::is_constructible<T, const U&>::value &&
- std::is_assignable<T&, const U&>::value,
- Optional&>
- operator=(const Optional<U>& other) {
- CopyAssign(other);
- return *this;
- }
-
- // Move assign the state of other.
- template <typename U>
- std::enable_if_t<!internal::IsAssignableFromOptional<T, U>::value &&
- std::is_constructible<T, U>::value &&
- std::is_assignable<T&, U>::value,
- Optional&>
- operator=(Optional<U>&& other) {
- MoveAssign(std::move(other));
- return *this;
- }
-
- constexpr const T* operator->() const {
- CHECK(storage_.is_populated_);
- return &storage_.value_;
- }
-
- constexpr T* operator->() {
- CHECK(storage_.is_populated_);
- return &storage_.value_;
- }
-
- constexpr const T& operator*() const & {
- CHECK(storage_.is_populated_);
- return storage_.value_;
- }
-
- constexpr T& operator*() & {
- CHECK(storage_.is_populated_);
- return storage_.value_;
- }
-
- constexpr const T&& operator*() const && {
- CHECK(storage_.is_populated_);
- return std::move(storage_.value_);
- }
-
- constexpr T&& operator*() && {
- CHECK(storage_.is_populated_);
- return std::move(storage_.value_);
- }
-
- constexpr explicit operator bool() const { return storage_.is_populated_; }
-
- constexpr bool has_value() const { return storage_.is_populated_; }
-
- constexpr T& value() & {
- CHECK(storage_.is_populated_);
- return storage_.value_;
- }
-
- constexpr const T& value() const & {
- CHECK(storage_.is_populated_);
- return storage_.value_;
- }
-
- constexpr T&& value() && {
- CHECK(storage_.is_populated_);
- return std::move(storage_.value_);
- }
-
- constexpr const T&& value() const && {
- CHECK(storage_.is_populated_);
- return std::move(storage_.value_);
- }
-
- template <class U>
- constexpr T value_or(U&& default_value) const& {
- // TODO(mlamouri): add the following assert when possible:
- // static_assert(std::is_copy_constructible<T>::value,
- // "T must be copy constructible");
- static_assert(std::is_convertible<U, T>::value,
- "U must be convertible to T");
- return storage_.is_populated_
- ? storage_.value_
- : static_cast<T>(std::forward<U>(default_value));
- }
-
- template <class U>
- constexpr T value_or(U&& default_value) && {
- // TODO(mlamouri): add the following assert when possible:
- // static_assert(std::is_move_constructible<T>::value,
- // "T must be move constructible");
- static_assert(std::is_convertible<U, T>::value,
- "U must be convertible to T");
- return storage_.is_populated_
- ? std::move(storage_.value_)
- : static_cast<T>(std::forward<U>(default_value));
- }
-
- void swap(Optional& other) {
- if (!storage_.is_populated_ && !other.storage_.is_populated_)
- return;
-
- if (storage_.is_populated_ != other.storage_.is_populated_) {
- if (storage_.is_populated_) {
- other.storage_.Init(std::move(storage_.value_));
- FreeIfNeeded();
- } else {
- storage_.Init(std::move(other.storage_.value_));
- other.FreeIfNeeded();
- }
- return;
- }
-
- DCHECK(storage_.is_populated_ && other.storage_.is_populated_);
- using std::swap;
- swap(**this, *other);
- }
-
- void reset() { FreeIfNeeded(); }
-
- template <class... Args>
- T& emplace(Args&&... args) {
- FreeIfNeeded();
- storage_.Init(std::forward<Args>(args)...);
- return storage_.value_;
- }
-
- template <class U, class... Args>
- std::enable_if_t<
- std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value,
- T&>
- emplace(std::initializer_list<U> il, Args&&... args) {
- FreeIfNeeded();
- storage_.Init(il, std::forward<Args>(args)...);
- return storage_.value_;
- }
-
- private:
- // Accessing template base class's protected member needs explicit
- // declaration to do so.
- using internal::OptionalBase<T>::CopyAssign;
- using internal::OptionalBase<T>::FreeIfNeeded;
- using internal::OptionalBase<T>::InitOrAssign;
- using internal::OptionalBase<T>::MoveAssign;
- using internal::OptionalBase<T>::storage_;
-};
-
-// Here after defines comparation operators. The definition follows
-// http://en.cppreference.com/w/cpp/utility/optional/operator_cmp
-// while bool() casting is replaced by has_value() to meet the chromium
-// style guide.
-template <class T, class U>
-constexpr bool operator==(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (lhs.has_value() != rhs.has_value())
- return false;
- if (!lhs.has_value())
- return true;
- return *lhs == *rhs;
-}
-
-template <class T, class U>
-constexpr bool operator!=(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (lhs.has_value() != rhs.has_value())
- return true;
- if (!lhs.has_value())
- return false;
- return *lhs != *rhs;
-}
-
-template <class T, class U>
-constexpr bool operator<(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (!rhs.has_value())
- return false;
- if (!lhs.has_value())
- return true;
- return *lhs < *rhs;
-}
-
-template <class T, class U>
-constexpr bool operator<=(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (!lhs.has_value())
- return true;
- if (!rhs.has_value())
- return false;
- return *lhs <= *rhs;
-}
-
-template <class T, class U>
-constexpr bool operator>(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (!lhs.has_value())
- return false;
- if (!rhs.has_value())
- return true;
- return *lhs > *rhs;
-}
-
-template <class T, class U>
-constexpr bool operator>=(const Optional<T>& lhs, const Optional<U>& rhs) {
- if (!rhs.has_value())
- return true;
- if (!lhs.has_value())
- return false;
- return *lhs >= *rhs;
-}
-
-template <class T>
-constexpr bool operator==(const Optional<T>& opt, nullopt_t) {
- return !opt;
-}
-
-template <class T>
-constexpr bool operator==(nullopt_t, const Optional<T>& opt) {
- return !opt;
-}
-
-template <class T>
-constexpr bool operator!=(const Optional<T>& opt, nullopt_t) {
- return opt.has_value();
-}
-
-template <class T>
-constexpr bool operator!=(nullopt_t, const Optional<T>& opt) {
- return opt.has_value();
-}
-
-template <class T>
-constexpr bool operator<(const Optional<T>& opt, nullopt_t) {
- return false;
-}
-
-template <class T>
-constexpr bool operator<(nullopt_t, const Optional<T>& opt) {
- return opt.has_value();
-}
-
-template <class T>
-constexpr bool operator<=(const Optional<T>& opt, nullopt_t) {
- return !opt;
-}
-
-template <class T>
-constexpr bool operator<=(nullopt_t, const Optional<T>& opt) {
- return true;
-}
-
-template <class T>
-constexpr bool operator>(const Optional<T>& opt, nullopt_t) {
- return opt.has_value();
-}
-
-template <class T>
-constexpr bool operator>(nullopt_t, const Optional<T>& opt) {
- return false;
-}
-
-template <class T>
-constexpr bool operator>=(const Optional<T>& opt, nullopt_t) {
- return true;
-}
-
-template <class T>
-constexpr bool operator>=(nullopt_t, const Optional<T>& opt) {
- return !opt;
-}
-
-template <class T, class U>
-constexpr bool operator==(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt == value : false;
-}
-
-template <class T, class U>
-constexpr bool operator==(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value == *opt : false;
-}
-
-template <class T, class U>
-constexpr bool operator!=(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt != value : true;
-}
-
-template <class T, class U>
-constexpr bool operator!=(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value != *opt : true;
-}
-
-template <class T, class U>
-constexpr bool operator<(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt < value : true;
-}
-
-template <class T, class U>
-constexpr bool operator<(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value < *opt : false;
-}
-
-template <class T, class U>
-constexpr bool operator<=(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt <= value : true;
-}
-
-template <class T, class U>
-constexpr bool operator<=(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value <= *opt : false;
-}
-
-template <class T, class U>
-constexpr bool operator>(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt > value : false;
-}
-
-template <class T, class U>
-constexpr bool operator>(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value > *opt : true;
-}
-
-template <class T, class U>
-constexpr bool operator>=(const Optional<T>& opt, const U& value) {
- return opt.has_value() ? *opt >= value : false;
-}
-
-template <class T, class U>
-constexpr bool operator>=(const U& value, const Optional<T>& opt) {
- return opt.has_value() ? value >= *opt : true;
-}
-
-template <class T>
-constexpr Optional<std::decay_t<T>> make_optional(T&& value) {
- return Optional<std::decay_t<T>>(std::forward<T>(value));
-}
-
-template <class T, class... Args>
-constexpr Optional<T> make_optional(Args&&... args) {
- return Optional<T>(in_place, std::forward<Args>(args)...);
-}
-
-template <class T, class U, class... Args>
-constexpr Optional<T> make_optional(std::initializer_list<U> il,
- Args&&... args) {
- return Optional<T>(in_place, il, std::forward<Args>(args)...);
-}
-
-// Partial specialization for a function template is not allowed. Also, it is
-// not allowed to add overload function to std namespace, while it is allowed
-// to specialize the template in std. Thus, swap() (kind of) overloading is
-// defined in pdfium namespace, instead.
-template <class T>
-std::enable_if_t<std::is_move_constructible<T>::value &&
- internal::IsSwappable<T>::value>
-swap(Optional<T>& lhs, Optional<T>& rhs) {
- lhs.swap(rhs);
-}
+using absl::make_optional;
+using absl::nullopt;
+using absl::nullopt_t;
} // namespace pdfium
-namespace std {
-
template <class T>
-struct hash<pdfium::Optional<T>> {
- size_t operator()(const pdfium::Optional<T>& opt) const {
- return opt == pdfium::nullopt ? 0 : std::hash<T>()(*opt);
- }
-};
-
-} // namespace std
-
-template <class T>
-using Optional = pdfium::Optional<T>;
+using Optional = absl::optional<T>;
#endif // THIRD_PARTY_BASE_OPTIONAL_H_
