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darling-WTF/wtf/Optional.h
Andrew Hyatt 0a81a832a1 Update WTF to the Hgih Sierra version
2018-01-05 13:44:16 -08:00

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// Copyright (C) 2011 - 2012 Andrzej Krzemienski.
//
// Use, modification, and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// The idea and interface is based on Boost.Optional library
// authored by Fernando Luis Cacciola Carballal
//
// Boost Software License - Version 1.0 - August 17th, 2003
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
// Copied from https://github.com/akrzemi1/Optional (8456c3923776b33b4ae852734273fe934c3e4e61)
// Modified to make it compile with exceptions disabled.
#pragma once
# include <utility>
# include <type_traits>
# include <initializer_list>
# include <cassert>
# include <string>
# include <stdexcept>
# include <wtf/Assertions.h>
# include <wtf/Compiler.h>
# include <wtf/StdLibExtras.h>
# define TR2_OPTIONAL_REQUIRES(...) typename std::enable_if<__VA_ARGS__::value, bool>::type = false
# if defined __GNUC__ // NOTE: GNUC is also defined for Clang
# if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)
# define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
# elif (__GNUC__ > 4)
# define TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
# endif
#
# if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)
# define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
# elif (__GNUC__ > 4)
# define TR2_OPTIONAL_GCC_4_7_AND_HIGHER___
# endif
#
# if (__GNUC__ == 4) && (__GNUC_MINOR__ == 8) && (__GNUC_PATCHLEVEL__ >= 1)
# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
# elif (__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)
# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
# elif (__GNUC__ > 4)
# define TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
# endif
# endif
#
# if defined __clang_major__
# if (__clang_major__ == 3 && __clang_minor__ >= 5)
# define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
# elif (__clang_major__ > 3)
# define TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
# endif
# if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_
# define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
# elif (__clang_major__ == 3 && __clang_minor__ == 4 && __clang_patchlevel__ >= 2)
# define TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
# endif
# endif
#
# if defined _MSC_VER
# if (_MSC_VER >= 1900)
# define TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
# endif
# endif
# if defined __clang__
# if (__clang_major__ > 2) || (__clang_major__ == 2) && (__clang_minor__ >= 9)
# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
# else
# define OPTIONAL_HAS_THIS_RVALUE_REFS 0
# endif
# elif defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
# elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
# define OPTIONAL_HAS_THIS_RVALUE_REFS 1
# else
# define OPTIONAL_HAS_THIS_RVALUE_REFS 0
# endif
# if defined TR2_OPTIONAL_GCC_4_8_1_AND_HIGHER___
# define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 1
# define OPTIONAL_CONSTEXPR_INIT_LIST constexpr
# else
# define OPTIONAL_HAS_CONSTEXPR_INIT_LIST 0
# define OPTIONAL_CONSTEXPR_INIT_LIST
# endif
// FIXME: To make the result of value() type consistent among the compilers, we now intentionally disables move accessors.
# define OPTIONAL_HAS_MOVE_ACCESSORS 0
// # if defined TR2_OPTIONAL_CLANG_3_5_AND_HIGHTER_ && (defined __cplusplus) && (__cplusplus != 201103L)
// # define OPTIONAL_HAS_MOVE_ACCESSORS 1
// # else
// # define OPTIONAL_HAS_MOVE_ACCESSORS 0
// # endif
# // In C++11 constexpr implies const, so we need to make non-const members also non-constexpr
# if (defined __cplusplus) && (__cplusplus == 201103L)
# define OPTIONAL_MUTABLE_CONSTEXPR
# else
# define OPTIONAL_MUTABLE_CONSTEXPR constexpr
# endif
#if COMPILER_SUPPORTS(EXCEPTIONS)
#define __THROW_EXCEPTION(__exception) throw __exception;
#define __NOEXCEPT noexcept
#define __NOEXCEPT_(__exception) noexcept(__exception)
#else
#define __THROW_EXCEPTION(__exception) do { (void)__exception; CRASH(); } while (0);
#define __NOEXCEPT
#define __NOEXCEPT_(...)
#endif
namespace std {
namespace detail_ {
// NOTE: All our target compilers support is_trivially_destructible.
// // BEGIN workaround for missing is_trivially_destructible
// # if defined TR2_OPTIONAL_GCC_4_8_AND_HIGHER___
// // leave it: it is already there
// # elif defined TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_
// // leave it: it is already there
// # elif defined TR2_OPTIONAL_MSVC_2015_AND_HIGHER___
// // leave it: it is already there
// # elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
// // leave it: the user doesn't want it
// # else
// template <typename T>
// using is_trivially_destructible = std::has_trivial_destructor<T>;
// # endif
// // END workaround for missing is_trivially_destructible
#if COMPILER_SUPPORTS(EXCEPTIONS)
# if defined(TR2_OPTIONAL_GCC_4_7_AND_HIGHER___) || defined(TR2_OPTIONAL_CLANG_3_4_2_AND_HIGHER_) || defined(TR2_OPTIONAL_MSVC_2015_AND_HIGHER___)
// leave it; our metafunctions are already defined.
template <typename T>
using is_nothrow_move_constructible = std::is_nothrow_move_constructible<T>;
template <typename T>
using is_nothrow_move_assignable = std::is_nothrow_move_assignable<T>;
# elif defined TR2_OPTIONAL_DISABLE_EMULATION_OF_TYPE_TRAITS
// leave it: the user doesn't want it
# else
// workaround for missing traits in GCC and CLANG
template <class T>
struct is_nothrow_move_constructible
{
constexpr static bool value = std::is_nothrow_constructible<T, T&&>::value;
};
template <class T, class U>
struct is_assignable
{
template <class X, class Y>
constexpr static bool has_assign(...) { return false; }
template <class X, class Y, size_t S = sizeof((std::declval<X>() = std::declval<Y>(), true)) >
// the comma operator is necessary for the cases where operator= returns void
constexpr static bool has_assign(bool) { return true; }
constexpr static bool value = has_assign<T, U>(true);
};
template <class T>
struct is_nothrow_move_assignable
{
template <class X, bool has_any_move_assign>
struct has_nothrow_move_assign {
constexpr static bool value = false;
};
template <class X>
struct has_nothrow_move_assign<X, true> {
constexpr static bool value = __NOEXCEPT_( std::declval<X&>() = std::declval<X&&>() );
};
constexpr static bool value = has_nothrow_move_assign<T, is_assignable<T&, T&&>::value>::value;
};
// end workaround
# endif
#endif
} // namespace detail_
// 20.5.4, optional for object types
template <class T> class optional;
// 20.5.5, optional for lvalue reference types
template <class T> class optional<T&>;
namespace detail_ {
// workaround: std utility functions aren't constexpr yet
template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type& t) __NOEXCEPT
{
return static_cast<T&&>(t);
}
template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type&& t) __NOEXCEPT
{
static_assert(!std::is_lvalue_reference<T>::value, "!!");
return static_cast<T&&>(t);
}
template <class T> inline constexpr typename std::remove_reference<T>::type&& constexpr_move(T&& t) __NOEXCEPT
{
return static_cast<typename std::remove_reference<T>::type&&>(t);
}
#if defined NDEBUG
# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) (EXPR)
#else
# define TR2_OPTIONAL_ASSERTED_EXPRESSION(CHECK, EXPR) ((CHECK) ? (EXPR) : ([]{assert(!#CHECK);}(), (EXPR)))
#endif
// static_addressof: a constexpr version of addressof
template <typename T>
struct has_overloaded_addressof
{
template <class X>
constexpr static bool has_overload(...) { return false; }
template <class X, size_t S = sizeof(std::declval<X&>().operator&()) >
constexpr static bool has_overload(bool) { return true; }
constexpr static bool value = has_overload<T>(true);
};
template <typename T, TR2_OPTIONAL_REQUIRES(!has_overloaded_addressof<T>)>
constexpr T* static_addressof(T& ref)
{
return &ref;
}
template <typename T, TR2_OPTIONAL_REQUIRES(has_overloaded_addressof<T>)>
T* static_addressof(T& ref)
{
return std::addressof(ref);
}
// the call to convert<A>(b) has return type A and converts b to type A iff b decltype(b) is implicitly convertible to A
template <class U>
constexpr U convert(U v) { return v; }
} // namespace detail
constexpr struct trivial_init_t{} trivial_init{};
// 20.5.6, In-place construction
constexpr struct in_place_t{} in_place{};
// 20.5.7, Disengaged state indicator
struct nullopt_t
{
struct init{};
constexpr explicit nullopt_t(init){}
};
constexpr nullopt_t nullopt{nullopt_t::init()};
// 20.5.8, class bad_optional_access
class bad_optional_access : public std::logic_error {
public:
explicit bad_optional_access(const std::string& what_arg) : std::logic_error{what_arg} {}
explicit bad_optional_access(const char* what_arg) : std::logic_error{what_arg} {}
};
template <class T>
union storage_t
{
unsigned char dummy_;
T value_;
constexpr storage_t( trivial_init_t ) __NOEXCEPT : dummy_() {};
template <class... Args>
constexpr storage_t( Args&&... args ) : value_(detail_::constexpr_forward<Args>(args)...) {}
~storage_t(){}
};
template <class T>
union constexpr_storage_t
{
unsigned char dummy_;
T value_;
constexpr constexpr_storage_t( trivial_init_t ) __NOEXCEPT : dummy_() {};
template <class... Args>
constexpr constexpr_storage_t( Args&&... args ) : value_(detail_::constexpr_forward<Args>(args)...) {}
~constexpr_storage_t() = default;
};
template <class T>
struct optional_base
{
bool init_;
storage_t<T> storage_;
constexpr optional_base() __NOEXCEPT : init_(false), storage_(trivial_init) {};
explicit constexpr optional_base(const T& v) : init_(true), storage_(v) {}
explicit constexpr optional_base(T&& v) : init_(true), storage_(detail_::constexpr_move(v)) {}
template <class... Args> explicit optional_base(in_place_t, Args&&... args)
: init_(true), storage_(detail_::constexpr_forward<Args>(args)...) {}
template <class U, class... Args, TR2_OPTIONAL_REQUIRES(std::is_constructible<T, std::initializer_list<U>>)>
explicit optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
: init_(true), storage_(il, std::forward<Args>(args)...) {}
~optional_base() { if (init_) storage_.value_.T::~T(); }
};
template <class T>
struct constexpr_optional_base
{
bool init_;
constexpr_storage_t<T> storage_;
constexpr constexpr_optional_base() __NOEXCEPT : init_(false), storage_(trivial_init) {};
explicit constexpr constexpr_optional_base(const T& v) : init_(true), storage_(v) {}
explicit constexpr constexpr_optional_base(T&& v) : init_(true), storage_(detail_::constexpr_move(v)) {}
template <class... Args> explicit constexpr constexpr_optional_base(in_place_t, Args&&... args)
: init_(true), storage_(detail_::constexpr_forward<Args>(args)...) {}
template <class U, class... Args, TR2_OPTIONAL_REQUIRES(std::is_constructible<T, std::initializer_list<U>>)>
OPTIONAL_CONSTEXPR_INIT_LIST explicit constexpr_optional_base(in_place_t, std::initializer_list<U> il, Args&&... args)
: init_(true), storage_(il, std::forward<Args>(args)...) {}
~constexpr_optional_base() = default;
};
template <class T>
using OptionalBase = typename std::conditional<
std::is_trivially_destructible<T>::value, // if possible
constexpr_optional_base<typename std::remove_const<T>::type>, // use base with trivial destructor
optional_base<typename std::remove_const<T>::type>
>::type;
template <class T>
class optional : private OptionalBase<T>
{
static_assert( !std::is_same<typename std::decay<T>::type, nullopt_t>::value, "bad T" );
static_assert( !std::is_same<typename std::decay<T>::type, in_place_t>::value, "bad T" );
constexpr bool initialized() const __NOEXCEPT { return OptionalBase<T>::init_; }
typename std::remove_const<T>::type* dataptr() { return std::addressof(OptionalBase<T>::storage_.value_); }
constexpr const T* dataptr() const { return detail_::static_addressof(OptionalBase<T>::storage_.value_); }
# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
constexpr const T& contained_val() const& { return OptionalBase<T>::storage_.value_; }
# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
OPTIONAL_MUTABLE_CONSTEXPR T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
OPTIONAL_MUTABLE_CONSTEXPR T& contained_val() & { return OptionalBase<T>::storage_.value_; }
# else
T& contained_val() & { return OptionalBase<T>::storage_.value_; }
T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }
# endif
# else
constexpr const T& contained_val() const { return OptionalBase<T>::storage_.value_; }
T& contained_val() { return OptionalBase<T>::storage_.value_; }
# endif
void clear() __NOEXCEPT {
if (initialized()) dataptr()->T::~T();
OptionalBase<T>::init_ = false;
}
template <class... Args>
void initialize(Args&&... args) __NOEXCEPT_(__NOEXCEPT_(T(std::forward<Args>(args)...)))
{
ASSERT(!OptionalBase<T>::init_);
::new (static_cast<void*>(dataptr())) T(std::forward<Args>(args)...);
OptionalBase<T>::init_ = true;
}
template <class U, class... Args>
void initialize(std::initializer_list<U> il, Args&&... args) __NOEXCEPT_(__NOEXCEPT_(T(il, std::forward<Args>(args)...)))
{
ASSERT(!OptionalBase<T>::init_);
::new (static_cast<void*>(dataptr())) T(il, std::forward<Args>(args)...);
OptionalBase<T>::init_ = true;
}
public:
typedef T value_type;
// 20.5.5.1, constructors
constexpr optional() __NOEXCEPT : OptionalBase<T>() {};
constexpr optional(nullopt_t) __NOEXCEPT : OptionalBase<T>() {};
optional(const optional& rhs)
: OptionalBase<T>()
{
if (rhs.initialized()) {
::new (static_cast<void*>(dataptr())) T(*rhs);
OptionalBase<T>::init_ = true;
}
}
optional(optional&& rhs) __NOEXCEPT_(detail_::is_nothrow_move_constructible<T>::value)
: OptionalBase<T>()
{
if (rhs.initialized()) {
::new (static_cast<void*>(dataptr())) T(std::move(*rhs));
OptionalBase<T>::init_ = true;
}
}
constexpr optional(const T& v) : OptionalBase<T>(v) {}
constexpr optional(T&& v) : OptionalBase<T>(detail_::constexpr_move(v)) {}
template <class... Args>
explicit constexpr optional(in_place_t, Args&&... args)
: OptionalBase<T>(in_place_t{}, detail_::constexpr_forward<Args>(args)...) {}
template <class U, class... Args, TR2_OPTIONAL_REQUIRES(std::is_constructible<T, std::initializer_list<U>>)>
OPTIONAL_CONSTEXPR_INIT_LIST explicit optional(in_place_t, std::initializer_list<U> il, Args&&... args)
: OptionalBase<T>(in_place_t{}, il, detail_::constexpr_forward<Args>(args)...) {}
// 20.5.4.2, Destructor
~optional() = default;
// 20.5.4.3, assignment
optional& operator=(nullopt_t) __NOEXCEPT
{
clear();
return *this;
}
optional& operator=(const optional& rhs)
{
if (initialized() == true && rhs.initialized() == false) clear();
else if (initialized() == false && rhs.initialized() == true) initialize(*rhs);
else if (initialized() == true && rhs.initialized() == true) contained_val() = *rhs;
return *this;
}
optional& operator=(optional&& rhs)
__NOEXCEPT_(detail_::is_nothrow_move_assignable<T>::value && detail_::is_nothrow_move_constructible<T>::value)
{
if (initialized() == true && rhs.initialized() == false) clear();
else if (initialized() == false && rhs.initialized() == true) initialize(std::move(*rhs));
else if (initialized() == true && rhs.initialized() == true) contained_val() = std::move(*rhs);
return *this;
}
template <class U>
auto operator=(U&& v)
-> typename std::enable_if
<
std::is_same<typename std::decay<U>::type, T>::value,
optional&
>::type
{
if (initialized()) { contained_val() = std::forward<U>(v); }
else { initialize(std::forward<U>(v)); }
return *this;
}
template <class... Args>
void emplace(Args&&... args)
{
clear();
initialize(std::forward<Args>(args)...);
}
template <class U, class... Args>
void emplace(std::initializer_list<U> il, Args&&... args)
{
clear();
initialize<U, Args...>(il, std::forward<Args>(args)...);
}
// 20.5.4.4, Swap
void swap(optional<T>& rhs) __NOEXCEPT_(detail_::is_nothrow_move_constructible<T>::value && __NOEXCEPT_(swap(std::declval<T&>(), std::declval<T&>())))
{
if (initialized() == true && rhs.initialized() == false) { rhs.initialize(std::move(**this)); clear(); }
else if (initialized() == false && rhs.initialized() == true) { initialize(std::move(*rhs)); rhs.clear(); }
else if (initialized() == true && rhs.initialized() == true) { using std::swap; swap(**this, *rhs); }
}
// 20.5.4.5, Observers
explicit constexpr operator bool() const __NOEXCEPT { return initialized(); }
constexpr bool has_value() const __NOEXCEPT { return initialized(); }
constexpr T const* operator ->() const {
return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), dataptr());
}
# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
OPTIONAL_MUTABLE_CONSTEXPR T* operator ->() {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// CONSTEXPR_ASSERT(initialized());
return dataptr();
}
constexpr T const& operator *() const& {
return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
}
OPTIONAL_MUTABLE_CONSTEXPR T& operator *() & {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// CONSTEXPR_ASSERT(initialized());
return contained_val();
}
OPTIONAL_MUTABLE_CONSTEXPR T&& operator *() && {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// CONSTEXPR_ASSERT(initialized());
return detail_::constexpr_move(contained_val());
}
constexpr T const& value() const& {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
return contained_val();
}
OPTIONAL_MUTABLE_CONSTEXPR T& value() & {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
return contained_val();
}
OPTIONAL_MUTABLE_CONSTEXPR T&& value() && {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// if (!initialized()) __THROW_EXCEPTION(bad_optional_access("bad optional access"));
return std::move(contained_val());
}
# else
T* operator ->() {
assert (initialized());
return dataptr();
}
constexpr T const& operator *() const {
return TR2_OPTIONAL_ASSERTED_EXPRESSION(initialized(), contained_val());
}
T& operator *() {
assert (initialized());
return contained_val();
}
constexpr T const& value() const {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
return contained_val();
}
T& value() {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// return initialized() ? contained_val() : (throw bad_optional_access("bad optional access"), contained_val());
return contained_val();
}
# endif
# if OPTIONAL_HAS_THIS_RVALUE_REFS == 1
template <class V>
constexpr T value_or(V&& v) const&
{
return *this ? **this : detail_::convert<T>(detail_::constexpr_forward<V>(v));
}
# if OPTIONAL_HAS_MOVE_ACCESSORS == 1
template <class V>
OPTIONAL_MUTABLE_CONSTEXPR T value_or(V&& v) &&
{
return *this ? detail_::constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(detail_::constexpr_forward<V>(v));
}
# else
template <class V>
T value_or(V&& v) &&
{
return *this ? detail_::constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<T>(detail_::constexpr_forward<V>(v));
}
# endif
# else
template <class V>
constexpr T value_or(V&& v) const
{
return *this ? **this : detail_::convert<T>(detail_::constexpr_forward<V>(v));
}
# endif
// 20.6.3.6, modifiers
void reset() __NOEXCEPT { clear(); }
};
template <class T>
class optional<T&>
{
static_assert( !std::is_same<T, nullopt_t>::value, "bad T" );
static_assert( !std::is_same<T, in_place_t>::value, "bad T" );
T* ref;
public:
// 20.5.5.1, construction/destruction
constexpr optional() __NOEXCEPT : ref(nullptr) {}
constexpr optional(nullopt_t) __NOEXCEPT : ref(nullptr) {}
constexpr optional(T& v) __NOEXCEPT : ref(detail_::static_addressof(v)) {}
optional(T&&) = delete;
constexpr optional(const optional& rhs) __NOEXCEPT : ref(rhs.ref) {}
explicit constexpr optional(in_place_t, T& v) __NOEXCEPT : ref(detail_::static_addressof(v)) {}
explicit optional(in_place_t, T&&) = delete;
~optional() = default;
// 20.5.5.2, mutation
optional& operator=(nullopt_t) __NOEXCEPT {
ref = nullptr;
return *this;
}
// optional& operator=(const optional& rhs) __NOEXCEPT {
// ref = rhs.ref;
// return *this;
// }
// optional& operator=(optional&& rhs) __NOEXCEPT {
// ref = rhs.ref;
// return *this;
// }
template <typename U>
auto operator=(U&& rhs) __NOEXCEPT
-> typename std::enable_if
<
std::is_same<typename std::decay<U>::type, optional<T&>>::value,
optional&
>::type
{
ref = rhs.ref;
return *this;
}
template <typename U>
auto operator=(U&& rhs) __NOEXCEPT
-> typename std::enable_if
<
!std::is_same<typename std::decay<U>::type, optional<T&>>::value,
optional&
>::type
= delete;
void emplace(T& v) __NOEXCEPT {
ref = detail_::static_addressof(v);
}
void emplace(T&&) = delete;
void swap(optional<T&>& rhs) __NOEXCEPT
{
std::swap(ref, rhs.ref);
}
// 20.5.5.3, observers
constexpr T* operator->() const {
return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, ref);
}
constexpr T& operator*() const {
return TR2_OPTIONAL_ASSERTED_EXPRESSION(ref, *ref);
}
constexpr T& value() const {
// FIXME: We need to offer special assert function that can be used under the contexpr context.
// return ref ? *ref : (throw bad_optional_access("bad optional access"), *ref);
return *ref;
}
explicit constexpr operator bool() const __NOEXCEPT {
return ref != nullptr;
}
constexpr bool has_value() const __NOEXCEPT {
return ref != nullptr;
}
template <class V>
constexpr typename std::decay<T>::type value_or(V&& v) const
{
return *this ? **this : detail_::convert<typename std::decay<T>::type>(detail_::constexpr_forward<V>(v));
}
// x.x.x.x, modifiers
void reset() __NOEXCEPT { ref = nullptr; }
};
template <class T>
class optional<T&&>
{
static_assert( sizeof(T) == 0, "optional rvalue references disallowed" );
};
// 20.5.8, Relational operators
template <class T> constexpr bool operator==(const optional<T>& x, const optional<T>& y)
{
return bool(x) != bool(y) ? false : bool(x) == false ? true : *x == *y;
}
template <class T> constexpr bool operator!=(const optional<T>& x, const optional<T>& y)
{
return !(x == y);
}
template <class T> constexpr bool operator<(const optional<T>& x, const optional<T>& y)
{
return (!y) ? false : (!x) ? true : *x < *y;
}
template <class T> constexpr bool operator>(const optional<T>& x, const optional<T>& y)
{
return (y < x);
}
template <class T> constexpr bool operator<=(const optional<T>& x, const optional<T>& y)
{
return !(y < x);
}
template <class T> constexpr bool operator>=(const optional<T>& x, const optional<T>& y)
{
return !(x < y);
}
// 20.5.9, Comparison with nullopt
template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) __NOEXCEPT
{
return (!x);
}
template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) __NOEXCEPT
{
return (!x);
}
template <class T> constexpr bool operator!=(const optional<T>& x, nullopt_t) __NOEXCEPT
{
return bool(x);
}
template <class T> constexpr bool operator!=(nullopt_t, const optional<T>& x) __NOEXCEPT
{
return bool(x);
}
template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) __NOEXCEPT
{
return false;
}
template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) __NOEXCEPT
{
return bool(x);
}
template <class T> constexpr bool operator<=(const optional<T>& x, nullopt_t) __NOEXCEPT
{
return (!x);
}
template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) __NOEXCEPT
{
return true;
}
template <class T> constexpr bool operator>(const optional<T>& x, nullopt_t) __NOEXCEPT
{
return bool(x);
}
template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) __NOEXCEPT
{
return false;
}
template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) __NOEXCEPT
{
return true;
}
template <class T> constexpr bool operator>=(nullopt_t, const optional<T>& x) __NOEXCEPT
{
return (!x);
}
// 20.5.10, Comparison with T
template <class T> constexpr bool operator==(const optional<T>& x, const T& v)
{
return bool(x) ? *x == v : false;
}
template <class T> constexpr bool operator==(const T& v, const optional<T>& x)
{
return bool(x) ? v == *x : false;
}
template <class T> constexpr bool operator!=(const optional<T>& x, const T& v)
{
return bool(x) ? *x != v : true;
}
template <class T> constexpr bool operator!=(const T& v, const optional<T>& x)
{
return bool(x) ? v != *x : true;
}
template <class T> constexpr bool operator<(const optional<T>& x, const T& v)
{
return bool(x) ? *x < v : true;
}
template <class T> constexpr bool operator>(const T& v, const optional<T>& x)
{
return bool(x) ? v > *x : true;
}
template <class T> constexpr bool operator>(const optional<T>& x, const T& v)
{
return bool(x) ? *x > v : false;
}
template <class T> constexpr bool operator<(const T& v, const optional<T>& x)
{
return bool(x) ? v < *x : false;
}
template <class T> constexpr bool operator>=(const optional<T>& x, const T& v)
{
return bool(x) ? *x >= v : false;
}
template <class T> constexpr bool operator<=(const T& v, const optional<T>& x)
{
return bool(x) ? v <= *x : false;
}
template <class T> constexpr bool operator<=(const optional<T>& x, const T& v)
{
return bool(x) ? *x <= v : true;
}
template <class T> constexpr bool operator>=(const T& v, const optional<T>& x)
{
return bool(x) ? v >= *x : true;
}
// Comparison of optional<T&> with T
template <class T> constexpr bool operator==(const optional<T&>& x, const T& v)
{
return bool(x) ? *x == v : false;
}
template <class T> constexpr bool operator==(const T& v, const optional<T&>& x)
{
return bool(x) ? v == *x : false;
}
template <class T> constexpr bool operator!=(const optional<T&>& x, const T& v)
{
return bool(x) ? *x != v : true;
}
template <class T> constexpr bool operator!=(const T& v, const optional<T&>& x)
{
return bool(x) ? v != *x : true;
}
template <class T> constexpr bool operator<(const optional<T&>& x, const T& v)
{
return bool(x) ? *x < v : true;
}
template <class T> constexpr bool operator>(const T& v, const optional<T&>& x)
{
return bool(x) ? v > *x : true;
}
template <class T> constexpr bool operator>(const optional<T&>& x, const T& v)
{
return bool(x) ? *x > v : false;
}
template <class T> constexpr bool operator<(const T& v, const optional<T&>& x)
{
return bool(x) ? v < *x : false;
}
template <class T> constexpr bool operator>=(const optional<T&>& x, const T& v)
{
return bool(x) ? *x >= v : false;
}
template <class T> constexpr bool operator<=(const T& v, const optional<T&>& x)
{
return bool(x) ? v <= *x : false;
}
template <class T> constexpr bool operator<=(const optional<T&>& x, const T& v)
{
return bool(x) ? *x <= v : true;
}
template <class T> constexpr bool operator>=(const T& v, const optional<T&>& x)
{
return bool(x) ? v >= *x : true;
}
// Comparison of optional<T const&> with T
template <class T> constexpr bool operator==(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x == v : false;
}
template <class T> constexpr bool operator==(const T& v, const optional<const T&>& x)
{
return bool(x) ? v == *x : false;
}
template <class T> constexpr bool operator!=(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x != v : true;
}
template <class T> constexpr bool operator!=(const T& v, const optional<const T&>& x)
{
return bool(x) ? v != *x : true;
}
template <class T> constexpr bool operator<(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x < v : true;
}
template <class T> constexpr bool operator>(const T& v, const optional<const T&>& x)
{
return bool(x) ? v > *x : true;
}
template <class T> constexpr bool operator>(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x > v : false;
}
template <class T> constexpr bool operator<(const T& v, const optional<const T&>& x)
{
return bool(x) ? v < *x : false;
}
template <class T> constexpr bool operator>=(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x >= v : false;
}
template <class T> constexpr bool operator<=(const T& v, const optional<const T&>& x)
{
return bool(x) ? v <= *x : false;
}
template <class T> constexpr bool operator<=(const optional<const T&>& x, const T& v)
{
return bool(x) ? *x <= v : true;
}
template <class T> constexpr bool operator>=(const T& v, const optional<const T&>& x)
{
return bool(x) ? v >= *x : true;
}
// 20.5.12, Specialized algorithms
template <class T>
void swap(optional<T>& x, optional<T>& y) __NOEXCEPT_(__NOEXCEPT_(x.swap(y)))
{
x.swap(y);
}
template <class T>
constexpr optional<typename std::decay<T>::type> make_optional(T&& v)
{
return optional<typename std::decay<T>::type>(detail_::constexpr_forward<T>(v));
}
template <class X>
constexpr optional<X&> make_optional(std::reference_wrapper<X> v)
{
return optional<X&>(v.get());
}
} // namespace std
namespace WTF {
// -- WebKit Additions --
template <class OptionalType, class Callback>
ALWAYS_INLINE
auto valueOrCompute(OptionalType optional, Callback callback) -> typename OptionalType::value_type
{
if (optional)
return *optional;
return callback();
}
} // namespace WTF
namespace std
{
template <typename T>
struct hash<std::optional<T>>
{
typedef typename hash<T>::result_type result_type;
typedef std::optional<T> argument_type;
constexpr result_type operator()(argument_type const& arg) const {
return arg ? std::hash<T>{}(*arg) : result_type{};
}
};
template <typename T>
struct hash<std::optional<T&>>
{
typedef typename hash<T>::result_type result_type;
typedef std::optional<T&> argument_type;
constexpr result_type operator()(argument_type const& arg) const {
return arg ? std::hash<T>{}(*arg) : result_type{};
}
};
}
# undef TR2_OPTIONAL_REQUIRES
# undef TR2_OPTIONAL_ASSERTED_EXPRESSION
using WTF::valueOrCompute;
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