Implement N3672, optional<T>.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@189772 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/optional b/include/optional
new file mode 100644
index 0000000..a8e6a99
--- /dev/null
+++ b/include/optional
@@ -0,0 +1,697 @@
+// -*- C++ -*-
+//===-------------------------- optional ----------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_OPTIONAL
+#define _LIBCPP_OPTIONAL
+
+/*
+ optional synopsis
+
+// C++1y
+
+#include <initializer_list>
+
+namespace std
+{
+
+// optional for object types
+template <class T>
+class optional
+{
+public:
+ typedef T value_type;
+
+ // constructors
+ constexpr optional() noexcept;
+ constexpr optional(nullopt_t) noexcept;
+ optional(const optional&);
+ optional(optional&&) noexcept(is_nothrow_move_constructible<T>::value);
+ constexpr optional(const T&);
+ constexpr optional(T&&);
+ template <class... Args> constexpr explicit optional(in_place_t, Args&&...);
+ template <class U, class... Args>
+ constexpr explicit optional(in_place_t, initializer_list<U>, Args&&...);
+
+ // destructor
+ ~optional();
+
+ // assignment
+ optional& operator=(nullopt_t) noexcept;
+ optional& operator=(const optional&);
+ optional& operator=(optional&&)
+ noexcept(is_nothrow_move_assignable<T>::value &&
+ is_nothrow_move_constructible<T>::value);
+ template <class U> optional& operator=(U&&);
+ template <class... Args> void emplace(Args&&...);
+ template <class U, class... Args> void emplace(initializer_list<U>, Args&&...);
+
+ // swap
+ void swap(optional&)
+ noexcept(is_nothrow_move_constructible<T>::value &&
+ noexcept(swap(declval<T&>(), declval<T&>())));
+
+ // observers
+ constexpr T const* operator->() const;
+ T* operator->();
+ constexpr T const& operator*() const;
+ T& operator*();
+ constexpr explicit operator bool() const noexcept;
+ constexpr T const& value() const;
+ T& value();
+ template <class U> constexpr T value_or(U&&) const&;
+ template <class U> T value_or(U&&) &&;
+};
+
+// In-place construction
+struct in_place_t{};
+constexpr in_place_t in_place{};
+
+// Disengaged state indicator
+struct nullopt_t{see below};
+constexpr nullopt_t nullopt(unspecified);
+
+// class bad_optional_access
+class bad_optional_access
+ : public logic_error
+{
+public:
+ explicit bad_optional_access(const string& what_arg);
+ explicit bad_optional_access(const char* what_arg);
+};
+
+// Relational operators
+template <class T> constexpr bool operator==(const optional<T>&, const optional<T>&);
+template <class T> constexpr bool operator< (const optional<T>&, const optional<T>&);
+
+// Comparison with nullopt
+template <class T> constexpr bool operator==(const optional<T>&, nullopt_t) noexcept;
+template <class T> constexpr bool operator==(nullopt_t, const optional<T>&) noexcept;
+template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept;
+template <class T> constexpr bool operator<(nullopt_t, const optional<T>&) noexcept;
+
+// Comparison with T
+template <class T> constexpr bool operator==(const optional<T>&, const T&);
+template <class T> constexpr bool operator==(const T&, const optional<T>&);
+template <class T> constexpr bool operator<(const optional<T>&, const T&);
+template <class T> constexpr bool operator<(const T&, const optional<T>&);
+
+// Specialized algorithms
+template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below);
+template <class T> constexpr optional<typename decay<T>::type> make_optional(T&&);
+
+// hash support
+template <class T> struct hash;
+template <class T> struct hash<optional<T>>;
+
+} // std
+
+*/
+
+#include <__config>
+#include <functional>
+#include <stdexcept>
+
+namespace std // purposefully not using versioning namespace
+{
+
+class _LIBCPP_EXCEPTION_ABI bad_optional_access
+ : public logic_error
+{
+public:
+#if _LIBCPP_STD_VER > 11
+ _LIBCPP_INLINE_VISIBILITY explicit bad_optional_access(const string& __arg)
+ : logic_error(__arg) {}
+ _LIBCPP_INLINE_VISIBILITY explicit bad_optional_access(const char* __arg)
+ : logic_error(__arg) {}
+ _LIBCPP_INLINE_VISIBILITY bad_optional_access(const bad_optional_access&) noexcept = default;
+ _LIBCPP_INLINE_VISIBILITY bad_optional_access& operator=(const bad_optional_access&) noexcept = default;
+#else
+private:
+ bad_optional_access(const bad_optional_access&);
+ bad_optional_access& operator=(const bad_optional_access&);
+public:
+#endif // _LIBCPP_STD_VER > 11
+ // Get the key function ~bad_optional_access() into the dylib even if not compiling for C++1y
+ virtual ~bad_optional_access() _NOEXCEPT;
+};
+
+} // std
+
+#if _LIBCPP_STD_VER > 11
+
+#include <initializer_list>
+#include <type_traits>
+#include <new>
+#include <__functional_base>
+
+#include <__undef_min_max>
+
+#ifdef _LIBCPP_DEBUG
+# include <__debug>
+#else
+# define _LIBCPP_ASSERT(x, m) ((void)0)
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct in_place_t {};
+constexpr in_place_t in_place{};
+
+struct nullopt_t
+{
+ explicit constexpr nullopt_t(int) noexcept {}
+};
+
+constexpr nullopt_t nullopt{0};
+
+template <class _Tp, bool = is_trivially_destructible<_Tp>::value>
+class __optional_storage
+{
+protected:
+ typedef _Tp value_type;
+ union
+ {
+ char __null_state_;
+ value_type __val_;
+ };
+ bool __engaged_ = false;
+
+ _LIBCPP_INLINE_VISIBILITY
+ ~__optional_storage()
+ {
+ if (__engaged_)
+ __val_.~value_type();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage() noexcept
+ : __null_state_('\0') {}
+
+ _LIBCPP_INLINE_VISIBILITY
+ __optional_storage(const __optional_storage& __x)
+ : __engaged_(__x.__engaged_)
+ {
+ if (__engaged_)
+ ::new(_VSTD::addressof(__val_)) value_type(__x.__val_);
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ __optional_storage(__optional_storage&& __x)
+ noexcept(is_nothrow_move_constructible<value_type>::value)
+ : __engaged_(__x.__engaged_)
+ {
+ if (__engaged_)
+ ::new(_VSTD::addressof(__val_)) value_type(_VSTD::move(__x.__val_));
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage(const value_type& __v)
+ : __val_(__v),
+ __engaged_(true) {}
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage(value_type&& __v)
+ : __val_(_VSTD::move(__v)),
+ __engaged_(true) {}
+
+ template <class... _Args>
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ explicit __optional_storage(in_place_t, _Args&&... __args)
+ : __val_(_VSTD::forward<_Args>(__args)...),
+ __engaged_(true) {}
+};
+
+template <class _Tp>
+class __optional_storage<_Tp, true>
+{
+protected:
+ typedef _Tp value_type;
+ union
+ {
+ char __null_state_;
+ value_type __val_;
+ };
+ bool __engaged_ = false;
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage() noexcept
+ : __null_state_('\0') {}
+
+ _LIBCPP_INLINE_VISIBILITY
+ __optional_storage(const __optional_storage& __x)
+ : __engaged_(__x.__engaged_)
+ {
+ if (__engaged_)
+ ::new(_VSTD::addressof(__val_)) value_type(__x.__val_);
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ __optional_storage(__optional_storage&& __x)
+ noexcept(is_nothrow_move_constructible<value_type>::value)
+ : __engaged_(__x.__engaged_)
+ {
+ if (__engaged_)
+ ::new(_VSTD::addressof(__val_)) value_type(_VSTD::move(__x.__val_));
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage(const value_type& __v)
+ : __val_(__v),
+ __engaged_(true) {}
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr __optional_storage(value_type&& __v)
+ : __val_(_VSTD::move(__v)),
+ __engaged_(true) {}
+
+ template <class... _Args>
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ explicit __optional_storage(in_place_t, _Args&&... __args)
+ : __val_(_VSTD::forward<_Args>(__args)...),
+ __engaged_(true) {}
+};
+
+template <class _Tp>
+class optional
+ : private __optional_storage<_Tp>
+{
+ typedef __optional_storage<_Tp> __base;
+public:
+ typedef _Tp value_type;
+
+ static_assert(!is_reference<value_type>::value,
+ "Instantiation of optional with a reference type is ill-formed.");
+ static_assert(!is_same<typename remove_cv<value_type>::type, in_place_t>::value,
+ "Instantiation of optional with a in_place_t type is ill-formed.");
+ static_assert(!is_same<typename remove_cv<value_type>::type, nullopt_t>::value,
+ "Instantiation of optional with a nullopt_t type is ill-formed.");
+ static_assert(is_object<value_type>::value,
+ "Instantiation of optional with a non-object type is undefined behavior.");
+ static_assert(is_nothrow_destructible<value_type>::value,
+ "Instantiation of optional with an object type that is not noexcept destructible is undefined behavior.");
+
+ _LIBCPP_INLINE_VISIBILITY constexpr optional() noexcept {}
+ _LIBCPP_INLINE_VISIBILITY optional(const optional&) = default;
+ _LIBCPP_INLINE_VISIBILITY optional(optional&&) = default;
+ _LIBCPP_INLINE_VISIBILITY ~optional() = default;
+ _LIBCPP_INLINE_VISIBILITY constexpr optional(nullopt_t) noexcept {}
+ _LIBCPP_INLINE_VISIBILITY constexpr optional(const value_type& __v)
+ : __base(__v) {}
+ _LIBCPP_INLINE_VISIBILITY constexpr optional(value_type&& __v)
+ : __base(_VSTD::move(__v)) {}
+
+ template <class... _Args,
+ class = typename enable_if
+ <
+ is_constructible<value_type, _Args...>::value
+ >::type
+ >
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ explicit optional(in_place_t, _Args&&... __args)
+ : __base(in_place, _VSTD::forward<_Args>(__args)...) {}
+
+ template <class _Up, class... _Args,
+ class = typename enable_if
+ <
+ is_constructible<value_type, initializer_list<_Up>&, _Args...>::value
+ >::type
+ >
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ explicit optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
+ : __base(in_place, __il, _VSTD::forward<_Args>(__args)...) {}
+
+ _LIBCPP_INLINE_VISIBILITY
+ optional& operator=(nullopt_t) noexcept
+ {
+ if (this->__engaged_)
+ {
+ this->__val_.~value_type();
+ this->__engaged_ = false;
+ }
+ return *this;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ optional&
+ operator=(const optional& __opt)
+ {
+ if (this->__engaged_ == __opt.__engaged_)
+ {
+ if (this->__engaged_)
+ this->__val_ = __opt.__val_;
+ }
+ else
+ {
+ if (this->__engaged_)
+ this->__val_.~value_type();
+ else
+ ::new(_VSTD::addressof(this->__val_)) value_type(__opt.__val_);
+ this->__engaged_ = __opt.__engaged_;
+ }
+ return *this;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ optional&
+ operator=(optional&& __opt)
+ noexcept(is_nothrow_move_assignable<value_type>::value &&
+ is_nothrow_move_constructible<value_type>::value)
+ {
+ if (this->__engaged_ == __opt.__engaged_)
+ {
+ if (this->__engaged_)
+ this->__val_ = _VSTD::move(__opt.__val_);
+ }
+ else
+ {
+ if (this->__engaged_)
+ this->__val_.~value_type();
+ else
+ ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::move(__opt.__val_));
+ this->__engaged_ = __opt.__engaged_;
+ }
+ return *this;
+ }
+
+ template <class _Up,
+ class = typename enable_if
+ <
+ is_same<typename remove_reference<_Up>::type, value_type>::value &&
+ is_constructible<value_type, _Up>::value &&
+ is_assignable<value_type&, _Up>::value
+ >::type
+ >
+ _LIBCPP_INLINE_VISIBILITY
+ optional&
+ operator=(_Up&& __v)
+ {
+ if (this->__engaged_)
+ this->__val_ = _VSTD::forward<_Up>(__v);
+ else
+ {
+ ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::forward<_Up>(__v));
+ this->__engaged_ = true;
+ }
+ return *this;
+ }
+
+ template <class... _Args,
+ class = typename enable_if
+ <
+ is_constructible<value_type, _Args...>::value
+ >::type
+ >
+ _LIBCPP_INLINE_VISIBILITY
+ void
+ emplace(_Args&&... __args)
+ {
+ *this = nullopt;
+ ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::forward<_Args>(__args)...);
+ this->__engaged_ = true;
+ }
+
+ template <class _Up, class... _Args,
+ class = typename enable_if
+ <
+ is_constructible<value_type, initializer_list<_Up>&, _Args...>::value
+ >::type
+ >
+ _LIBCPP_INLINE_VISIBILITY
+ void
+ emplace(initializer_list<_Up> __il, _Args&&... __args)
+ {
+ *this = nullopt;
+ ::new(_VSTD::addressof(this->__val_)) value_type(__il, _VSTD::forward<_Args>(__args)...);
+ this->__engaged_ = true;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ void
+ swap(optional& __opt)
+ noexcept(is_nothrow_move_constructible<value_type>::value &&
+ __is_nothrow_swappable<value_type>::value)
+ {
+ using _VSTD::swap;
+ if (this->__engaged_ == __opt.__engaged_)
+ {
+ if (this->__engaged_)
+ swap(this->__val_, __opt.__val_);
+ }
+ else
+ {
+ if (this->__engaged_)
+ {
+ ::new(_VSTD::addressof(__opt.__val_)) value_type(_VSTD::move(this->__val_));
+ this->__val_.~value_type();
+ }
+ else
+ {
+ ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::move(__opt.__val_));
+ __opt.__val_.~value_type();
+ }
+ swap(this->__engaged_, __opt.__engaged_);
+ }
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ value_type const*
+ operator->() const
+ {
+ _LIBCPP_ASSERT(this->__engaged_, "optional operator-> called for disengaged value");
+ return __operator_arrow(__has_operator_addressof<value_type>{});
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ value_type*
+ operator->()
+ {
+ _LIBCPP_ASSERT(this->__engaged_, "optional operator-> called for disengaged value");
+ return _VSTD::addressof(this->__val_);
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ const value_type&
+ operator*() const
+ {
+ _LIBCPP_ASSERT(this->__engaged_, "optional operator* called for disengaged value");
+ return this->__val_;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ value_type&
+ operator*()
+ {
+ _LIBCPP_ASSERT(this->__engaged_, "optional operator* called for disengaged value");
+ return this->__val_;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr explicit operator bool() const noexcept {return this->__engaged_;}
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr value_type const& value() const
+ {
+ if (!this->__engaged_)
+ throw bad_optional_access("optional<T>::value: not engaged");
+ return this->__val_;
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ value_type& value()
+ {
+ if (!this->__engaged_)
+ throw bad_optional_access("optional<T>::value: not engaged");
+ return this->__val_;
+ }
+
+ template <class _Up>
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr value_type value_or(_Up&& __v) const&
+ {
+ static_assert(is_copy_constructible<value_type>::value,
+ "optional<T>::value_or: T must be copy constructible");
+ static_assert(is_convertible<_Up, value_type>::value,
+ "optional<T>::value_or: U must be convertible to T");
+ return this->__engaged_ ? this->__val_ :
+ static_cast<value_type>(_VSTD::forward<_Up>(__v));
+ }
+
+ template <class _Up>
+ _LIBCPP_INLINE_VISIBILITY
+ value_type value_or(_Up&& __v) &&
+ {
+ static_assert(is_move_constructible<value_type>::value,
+ "optional<T>::value_or: T must be move constructible");
+ static_assert(is_convertible<_Up, value_type>::value,
+ "optional<T>::value_or: U must be convertible to T");
+ return this->__engaged_ ? _VSTD::move(this->__val_) :
+ static_cast<value_type>(_VSTD::forward<_Up>(__v));
+ }
+
+private:
+ _LIBCPP_INLINE_VISIBILITY
+ value_type const*
+ __operator_arrow(true_type) const
+ {
+ return _VSTD::addressof(this->__val_);
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ constexpr
+ value_type const*
+ __operator_arrow(false_type) const
+ {
+ return &this->__val_;
+ }
+};
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+ if (static_cast<bool>(__x) != static_cast<bool>(__y))
+ return false;
+ if (!static_cast<bool>(__x))
+ return true;
+ return *__x == *__y;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(const optional<_Tp>& __x, const optional<_Tp>& __y)
+{
+ if (!static_cast<bool>(__y))
+ return false;
+ if (!static_cast<bool>(__x))
+ return true;
+ return less<_Tp>{}(*__x, *__y);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(const optional<_Tp>& __x, nullopt_t) noexcept
+{
+ return !static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+ return !static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(const optional<_Tp>&, nullopt_t) noexcept
+{
+ return false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(nullopt_t, const optional<_Tp>& __x) noexcept
+{
+ return static_cast<bool>(__x);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(const optional<_Tp>& __x, const _Tp& __v)
+{
+ return static_cast<bool>(__x) ? *__x == __v : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator==(const _Tp& __v, const optional<_Tp>& __x)
+{
+ return static_cast<bool>(__x) ? *__x == __v : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(const optional<_Tp>& __x, const _Tp& __v)
+{
+ return static_cast<bool>(__x) ? less<_Tp>{}(*__x, __v) : true;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+bool
+operator<(const _Tp& __v, const optional<_Tp>& __x)
+{
+ return static_cast<bool>(__x) ? less<_Tp>{}(__v, *__x) : false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(optional<_Tp>& __x, optional<_Tp>& __y) noexcept(noexcept(__x.swap(__y)))
+{
+ __x.swap(__y);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr
+optional<typename decay<_Tp>::type>
+make_optional(_Tp&& __v)
+{
+ return optional<typename decay<_Tp>::type>(_VSTD::forward<_Tp>(__v));
+}
+
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY hash<optional<_Tp> >
+{
+ typedef optional<_Tp> argument_type;
+ typedef size_t result_type;
+
+ _LIBCPP_INLINE_VISIBILITY
+ result_type operator()(const argument_type& __opt) const _NOEXCEPT
+ {
+ return static_cast<bool>(__opt) ? hash<_Tp>()(*__opt) : 0;
+ }
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 11
+
+#endif // _LIBCPP_ARRAY