diff options
Diffstat (limited to 'security/sandbox/chromium/base/optional.h')
| -rw-r--r-- | security/sandbox/chromium/base/optional.h | 937 |
1 files changed, 937 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/optional.h b/security/sandbox/chromium/base/optional.h new file mode 100644 index 0000000000..36ae36fc98 --- /dev/null +++ b/security/sandbox/chromium/base/optional.h @@ -0,0 +1,937 @@ +// Copyright 2016 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef BASE_OPTIONAL_H_ +#define BASE_OPTIONAL_H_ + +#include <functional> +#include <type_traits> +#include <utility> + +#include "base/logging.h" +#include "base/template_util.h" + +namespace base { + +// 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 { + +template <typename T, bool = std::is_trivially_destructible<T>::value> +struct OptionalStorageBase { + // Initializing |empty_| here instead of using default member initializing + // to avoid errors in g++ 4.8. + constexpr OptionalStorageBase() : empty_('\0') {} + + 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 { + // |empty_| 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'. + char empty_; + T value_; + }; +}; + +template <typename T> +struct OptionalStorageBase<T, true /* trivially destructible */> { + // Initializing |empty_| here instead of using default member initializing + // to avoid errors in g++ 4.8. + constexpr OptionalStorageBase() : empty_('\0') {} + + 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 { + // |empty_| 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'. + char empty_; + 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> +struct IsConvertibleFromOptional + : std::integral_constant< + bool, + std::is_constructible<T, Optional<U>&>::value || + std::is_constructible<T, const Optional<U>&>::value || + std::is_constructible<T, Optional<U>&&>::value || + std::is_constructible<T, const Optional<U>&&>::value || + std::is_convertible<Optional<U>&, T>::value || + std::is_convertible<const Optional<U>&, T>::value || + std::is_convertible<Optional<U>&&, T>::value || + std::is_convertible<const Optional<U>&&, T>::value> {}; + +template <typename T, typename U> +struct IsAssignableFromOptional + : std::integral_constant< + bool, + IsConvertibleFromOptional<T, U>::value || + std::is_assignable<T&, Optional<U>&>::value || + std::is_assignable<T&, const Optional<U>&>::value || + std::is_assignable<T&, Optional<U>&&>::value || + std::is_assignable<T&, const Optional<U>&&>::value> {}; + +// 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 + +// base::Optional is a Chromium 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/+/master/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 Chromium. +// Marked noexcept for only move constructor and move assign operators. +// - All the non-members are in the 'base' 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 base::Optional with in_place_t is ill-formed"); + static_assert(!std::is_same<internal::RemoveCvRefT<T>, nullopt_t>::value, + "instantiation of base::Optional with nullopt_t is ill-formed"); + static_assert( + !std::is_reference<T>::value, + "instantiation of base::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 base::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 base::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 base 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); +} + +} // namespace base + +namespace std { + +template <class T> +struct hash<base::Optional<T>> { + size_t operator()(const base::Optional<T>& opt) const { + return opt == base::nullopt ? 0 : std::hash<T>()(*opt); + } +}; + +} // namespace std + +#endif // BASE_OPTIONAL_H_ |