boost/optional/optional.hpp
// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal. // Copyright (C) 2014 - 2021 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) // // See http://www.boost.org/libs/optional for documentation. // // You are welcome to contact the author at: // fernando_cacciola@hotmail.com // // Revisions: // 27 Apr 2008 (improved swap) Fernando Cacciola, Niels Dekker, Thorsten Ottosen // 05 May 2014 (Added move semantics) Andrzej Krzemienski // #ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP #define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP #include <new> #ifndef BOOST_NO_IOSTREAM #include <iosfwd> #endif // BOOST_NO_IOSTREAM #include <boost/assert.hpp> #include <boost/core/addressof.hpp> #include <boost/core/enable_if.hpp> #include <boost/core/invoke_swap.hpp> #include <boost/core/launder.hpp> #include <boost/optional/bad_optional_access.hpp> #include <boost/throw_exception.hpp> #include <boost/type_traits/alignment_of.hpp> #include <boost/type_traits/conditional.hpp> #include <boost/type_traits/conjunction.hpp> #include <boost/type_traits/disjunction.hpp> #include <boost/type_traits/has_nothrow_constructor.hpp> #include <boost/type_traits/type_with_alignment.hpp> #include <boost/type_traits/remove_const.hpp> #include <boost/type_traits/remove_reference.hpp> #include <boost/type_traits/decay.hpp> #include <boost/type_traits/is_assignable.hpp> #include <boost/type_traits/is_base_of.hpp> #include <boost/type_traits/is_const.hpp> #include <boost/type_traits/is_constructible.hpp> #include <boost/type_traits/is_convertible.hpp> #include <boost/type_traits/is_lvalue_reference.hpp> #include <boost/type_traits/is_nothrow_move_assignable.hpp> #include <boost/type_traits/is_nothrow_move_constructible.hpp> #include <boost/type_traits/is_rvalue_reference.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/type_traits/is_volatile.hpp> #include <boost/type_traits/is_scalar.hpp> #include <boost/none.hpp> #include <boost/optional/optional_fwd.hpp> #include <boost/optional/detail/optional_config.hpp> #include <boost/optional/detail/optional_factory_support.hpp> #include <boost/optional/detail/optional_aligned_storage.hpp> #include <boost/optional/detail/optional_hash.hpp> #include <boost/optional/detail/optional_utility.hpp> namespace boost { namespace optional_detail { template <typename T> struct optional_value_type { }; template <typename U> struct optional_value_type< ::boost::optional<U> > { typedef U type; }; template <typename T> T declval(); // implementing my own result_of so that it works for C++11 (std::result_of) // and in C++20 (std::invoke_result). template <typename F, typename Ref, typename Rslt = decltype(declval<F>()(declval<Ref>()))> struct result_of { typedef Rslt type; }; template <typename F, typename Ref, typename Rslt = typename optional_value_type<typename result_of<F, Ref>::type>::type> struct result_value_type { typedef Rslt type; }; // optional<typename optional_detail::optional_value_type<decltype(optional_detail::declval<F>()(optional_detail::declval<reference_type>()))>::type> }} // namespace boost::optional_detail namespace boost { namespace optional_ns { // a tag for in-place initialization of contained value struct in_place_init_t { struct init_tag{}; BOOST_CONSTEXPR explicit in_place_init_t(init_tag){} }; BOOST_INLINE_CONSTEXPR in_place_init_t in_place_init ((in_place_init_t::init_tag())); // a tag for conditional in-place initialization of contained value struct in_place_init_if_t { struct init_tag{}; BOOST_CONSTEXPR explicit in_place_init_if_t(init_tag){} }; BOOST_INLINE_CONSTEXPR in_place_init_if_t in_place_init_if ((in_place_init_if_t::init_tag())); } // namespace optional_ns using optional_ns::in_place_init_t; using optional_ns::in_place_init; using optional_ns::in_place_init_if_t; using optional_ns::in_place_init_if; namespace optional_detail { struct init_value_tag {}; struct optional_tag {}; template<class T> class optional_base : public optional_tag { private : typedef aligned_storage<T> storage_type ; typedef optional_base<T> this_type ; protected : typedef T value_type ; typedef typename boost::remove_const<T>::type unqualified_value_type; protected: typedef T & reference_type ; typedef T const& reference_const_type ; typedef T && rval_reference_type ; typedef T && reference_type_of_temporary_wrapper ; typedef T * pointer_type ; typedef T const* pointer_const_type ; typedef T const& argument_type ; // Creates an optional<T> uninitialized. // No-throw optional_base() : m_initialized(false) {} // Creates an optional<T> uninitialized. // No-throw optional_base ( none_t ) : m_initialized(false) {} // Creates an optional<T> initialized with 'val'. // Can throw if T::T(T const&) does optional_base ( init_value_tag, argument_type val ) : m_initialized(false) { construct(val); } // move-construct an optional<T> initialized from an rvalue-ref to 'val'. // Can throw if T::T(T&&) does optional_base ( init_value_tag, rval_reference_type val ) : m_initialized(false) { construct( optional_detail::move(val) ); } // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialized optional<T>. // Can throw if T::T(T const&) does optional_base ( bool cond, argument_type val ) : m_initialized(false) { if ( cond ) construct(val); } // Creates an optional<T> initialized with 'move(val)' IFF cond is true, otherwise creates an uninitialized optional<T>. // Can throw if T::T(T &&) does optional_base ( bool cond, rval_reference_type val ) : m_initialized(false) { if ( cond ) construct(optional_detail::move(val)); } // Creates a deep copy of another optional<T> // Can throw if T::T(T const&) does optional_base ( optional_base const& rhs ) : m_initialized(false) { if ( rhs.is_initialized() ) construct(rhs.get_impl()); } // Creates a deep move of another optional<T> // Can throw if T::T(T&&) does optional_base ( optional_base&& rhs ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value) : m_initialized(false) { if ( rhs.is_initialized() ) construct( optional_detail::move(rhs.get_impl()) ); } template<class Expr, class PtrExpr> explicit optional_base ( Expr&& expr, PtrExpr const* tag ) : m_initialized(false) { construct(optional_detail::forward<Expr>(expr),tag); } optional_base& operator= ( optional_base const& rhs ) { this->assign(rhs); return *this; } optional_base& operator= ( optional_base && rhs ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value) { this->assign(static_cast<optional_base&&>(rhs)); return *this; } // No-throw (assuming T::~T() doesn't) ~optional_base() { destroy() ; } // Assigns from another optional<T> (deep-copies the rhs value) void assign ( optional_base const& rhs ) { if (is_initialized()) { if ( rhs.is_initialized() ) assign_value(rhs.get_impl()); else destroy(); } else { if ( rhs.is_initialized() ) construct(rhs.get_impl()); } } // Assigns from another optional<T> (deep-moves the rhs value) void assign ( optional_base&& rhs ) { if (is_initialized()) { if ( rhs.is_initialized() ) assign_value( optional_detail::move(rhs.get_impl()) ); else destroy(); } else { if ( rhs.is_initialized() ) construct(optional_detail::move(rhs.get_impl())); } } // Assigns from another _convertible_ optional<U> (deep-copies the rhs value) template<class U> void assign ( optional<U> const& rhs ) { if (is_initialized()) { if ( rhs.is_initialized() ) #ifndef BOOST_OPTIONAL_CONFIG_RESTORE_ASSIGNMENT_OF_NONCONVERTIBLE_TYPES assign_value( rhs.get() ); #else assign_value( static_cast<value_type>(rhs.get()) ); #endif else destroy(); } else { if ( rhs.is_initialized() ) #ifndef BOOST_OPTIONAL_CONFIG_RESTORE_ASSIGNMENT_OF_NONCONVERTIBLE_TYPES construct(rhs.get()); #else construct(static_cast<value_type>(rhs.get())); #endif } } // move-assigns from another _convertible_ optional<U> (deep-moves from the rhs value) template<class U> void assign ( optional<U>&& rhs ) { typedef BOOST_DEDUCED_TYPENAME optional<U>::rval_reference_type ref_type; if (is_initialized()) { if ( rhs.is_initialized() ) assign_value( static_cast<ref_type>(rhs.get()) ); else destroy(); } else { if ( rhs.is_initialized() ) construct(static_cast<ref_type>(rhs.get())); } } // Assigns from a T (deep-copies the rhs value) void assign ( argument_type val ) { if (is_initialized()) assign_value(val); else construct(val); } // Assigns from a T (deep-moves the rhs value) void assign ( rval_reference_type val ) { if (is_initialized()) assign_value( optional_detail::move(val) ); else construct( optional_detail::move(val) ); } // Assigns from "none", destroying the current value, if any, leaving this UNINITIALIZED // No-throw (assuming T::~T() doesn't) void assign ( none_t ) BOOST_NOEXCEPT { destroy(); } #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT template<class Expr, class ExprPtr> void assign_expr ( Expr&& expr, ExprPtr const* tag ) { if (is_initialized()) assign_expr_to_initialized(optional_detail::forward<Expr>(expr),tag); else construct(optional_detail::forward<Expr>(expr),tag); } #endif public : // Destroys the current value, if any, leaving this UNINITIALIZED // No-throw (assuming T::~T() doesn't) void reset() BOOST_NOEXCEPT { destroy(); } // **DEPRECATED** Replaces the current value -if any- with 'val' void reset ( argument_type val ) { assign(val); } // Returns a pointer to the value if this is initialized, otherwise, // returns NULL. // No-throw pointer_const_type get_ptr() const { return m_initialized ? get_ptr_impl() : 0 ; } pointer_type get_ptr() { return m_initialized ? get_ptr_impl() : 0 ; } bool is_initialized() const BOOST_NOEXCEPT { return m_initialized ; } protected : void construct ( argument_type val ) { ::new (m_storage.address()) unqualified_value_type(val) ; m_initialized = true ; } void construct ( rval_reference_type val ) { ::new (m_storage.address()) unqualified_value_type( optional_detail::move(val) ) ; m_initialized = true ; } // Constructs in-place // upon exception *this is always uninitialized template<class... Args> void construct ( in_place_init_t, Args&&... args ) { ::new (m_storage.address()) unqualified_value_type( optional_detail::forward<Args>(args)... ) ; m_initialized = true ; } template<class... Args> void emplace_assign ( Args&&... args ) { destroy(); construct(in_place_init, optional_detail::forward<Args>(args)...); } template<class... Args> explicit optional_base ( in_place_init_t, Args&&... args ) : m_initialized(false) { construct(in_place_init, optional_detail::forward<Args>(args)...); } template<class... Args> explicit optional_base ( in_place_init_if_t, bool cond, Args&&... args ) : m_initialized(false) { if ( cond ) construct(in_place_init, optional_detail::forward<Args>(args)...); } #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT // Constructs in-place using the given factory template<class Expr> void construct ( Expr&& factory, in_place_factory_base const* ) { boost_optional_detail::construct<value_type>(factory, m_storage.address()); m_initialized = true ; } // Constructs in-place using the given typed factory template<class Expr> void construct ( Expr&& factory, typed_in_place_factory_base const* ) { factory.apply(m_storage.address()) ; m_initialized = true ; } template<class Expr> void assign_expr_to_initialized ( Expr&& factory, in_place_factory_base const* tag ) { destroy(); construct(factory,tag); } // Constructs in-place using the given typed factory template<class Expr> void assign_expr_to_initialized ( Expr&& factory, typed_in_place_factory_base const* tag ) { destroy(); construct(factory,tag); } #endif // Constructs using any expression implicitly convertible to the single argument // of a one-argument T constructor. // Converting constructions of optional<T> from optional<U> uses this function with // 'Expr' being of type 'U' and relying on a converting constructor of T from U. template<class Expr> void construct ( Expr&& expr, void const* ) { new (m_storage.address()) unqualified_value_type(optional_detail::forward<Expr>(expr)) ; m_initialized = true ; } // Assigns using a form any expression implicitly convertible to the single argument // of a T's assignment operator. // Converting assignments of optional<T> from optional<U> uses this function with // 'Expr' being of type 'U' and relying on a converting assignment of T from U. template<class Expr> void assign_expr_to_initialized ( Expr&& expr, void const* ) { assign_value( optional_detail::forward<Expr>(expr) ); } #ifdef BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION // BCB5.64 (and probably lower versions) workaround. // The in-place factories are supported by means of catch-all constructors // and assignment operators (the functions are parameterized in terms of // an arbitrary 'Expr' type) // This compiler incorrectly resolves the overload set and sinks optional<T> and optional<U> // to the 'Expr'-taking functions even though explicit overloads are present for them. // Thus, the following overload is needed to properly handle the case when the 'lhs' // is another optional. // // For VC<=70 compilers this workaround doesn't work because the compiler issues and error // instead of choosing the wrong overload // // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>) template<class Expr> void construct ( Expr&& expr, optional_tag const* ) { if ( expr.is_initialized() ) { // An exception can be thrown here. // It it happens, THIS will be left uninitialized. new (m_storage.address()) unqualified_value_type(optional_detail::move(expr.get())) ; m_initialized = true ; } } #endif // defined BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION void assign_value ( argument_type val ) { get_impl() = val; } void assign_value ( rval_reference_type val ) { get_impl() = static_cast<rval_reference_type>(val); } void destroy() { if ( m_initialized ) destroy_impl() ; } reference_const_type get_impl() const { return m_storage.ref() ; } reference_type get_impl() { return m_storage.ref() ; } pointer_const_type get_ptr_impl() const { return m_storage.ptr_ref(); } pointer_type get_ptr_impl() { return m_storage.ptr_ref(); } private : #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1900)) void destroy_impl ( ) { m_storage.ptr_ref()->~T() ; m_initialized = false ; } #else void destroy_impl ( ) { m_storage.ref().T::~T() ; m_initialized = false ; } #endif bool m_initialized ; storage_type m_storage ; } ; #include <boost/optional/detail/optional_trivially_copyable_base.hpp> // definition of metafunction is_optional_val_init_candidate template <typename U> struct is_optional_or_tag : boost::conditional< boost::is_base_of<optional_detail::optional_tag, BOOST_DEDUCED_TYPENAME boost::decay<U>::type>::value || boost::is_same<BOOST_DEDUCED_TYPENAME boost::decay<U>::type, none_t>::value || boost::is_same<BOOST_DEDUCED_TYPENAME boost::decay<U>::type, in_place_init_t>::value || boost::is_same<BOOST_DEDUCED_TYPENAME boost::decay<U>::type, in_place_init_if_t>::value, boost::true_type, boost::false_type>::type {}; template <typename T, typename U> struct has_dedicated_constructor : boost::disjunction<is_optional_or_tag<U>, boost::is_same<T, BOOST_DEDUCED_TYPENAME boost::decay<U>::type> > {}; template <typename U> struct is_in_place_factory : boost::disjunction< boost::is_base_of<boost::in_place_factory_base, BOOST_DEDUCED_TYPENAME boost::decay<U>::type>, boost::is_base_of<boost::typed_in_place_factory_base, BOOST_DEDUCED_TYPENAME boost::decay<U>::type> > {}; #if !defined(BOOST_OPTIONAL_DETAIL_NO_IS_CONSTRUCTIBLE_TRAIT) template <typename T, typename U> struct is_factory_or_constructible_to_T : boost::disjunction< is_in_place_factory<U>, boost::is_constructible<T, U&&> > {}; template <typename T, typename U> struct is_optional_constructible : boost::is_constructible<T, U> {}; #else template <typename, typename> struct is_factory_or_constructible_to_T : boost::true_type {}; template <typename T, typename U> struct is_optional_constructible : boost::true_type {}; #endif // is_convertible condition #if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) // for is_assignable // On some initial rvalue reference implementations GCC does it in a strange way, // preferring perfect-forwarding constructor to implicit copy constructor. template <typename T, typename U> struct is_opt_assignable : boost::conjunction<boost::is_convertible<U&&, T>, boost::is_assignable<T&, U&&> > {}; #else template <typename T, typename U> struct is_opt_assignable : boost::is_convertible<U, T> {}; #endif template <typename T, typename U> struct is_factory_or_opt_assignable_to_T : boost::disjunction< is_in_place_factory<U>, is_opt_assignable<T, U> > {}; template <typename T, typename U, bool = has_dedicated_constructor<T, U>::value> struct is_optional_val_init_candidate : boost::false_type {}; template <typename T, typename U> struct is_optional_val_init_candidate<T, U, false> : is_factory_or_constructible_to_T<T, U> {}; template <typename T, typename U, bool = has_dedicated_constructor<T, U>::value> struct is_optional_val_assign_candidate : boost::false_type {}; template <typename T, typename U> struct is_optional_val_assign_candidate<T, U, false> : is_factory_or_opt_assignable_to_T<T, U> {}; } // namespace optional_detail namespace optional_config { template <typename T> struct optional_uses_direct_storage_for : boost::conditional<(boost::is_scalar<T>::value && !boost::is_const<T>::value && !boost::is_volatile<T>::value) , boost::true_type, boost::false_type>::type {}; } // namespace optional_config #ifndef BOOST_OPTIONAL_DETAIL_NO_DIRECT_STORAGE_SPEC # define BOOST_OPTIONAL_BASE_TYPE(T) boost::conditional< optional_config::optional_uses_direct_storage_for<T>::value, \ optional_detail::tc_optional_base<T>, \ optional_detail::optional_base<T> \ >::type #else # define BOOST_OPTIONAL_BASE_TYPE(T) optional_detail::optional_base<T> #endif template<class T> class optional : public BOOST_OPTIONAL_BASE_TYPE(T) { typedef typename BOOST_OPTIONAL_BASE_TYPE(T) base ; public : typedef optional<T> this_type ; typedef BOOST_DEDUCED_TYPENAME base::value_type value_type ; typedef BOOST_DEDUCED_TYPENAME base::reference_type reference_type ; typedef BOOST_DEDUCED_TYPENAME base::reference_const_type reference_const_type ; typedef BOOST_DEDUCED_TYPENAME base::rval_reference_type rval_reference_type ; typedef BOOST_DEDUCED_TYPENAME base::reference_type_of_temporary_wrapper reference_type_of_temporary_wrapper ; typedef BOOST_DEDUCED_TYPENAME base::pointer_type pointer_type ; typedef BOOST_DEDUCED_TYPENAME base::pointer_const_type pointer_const_type ; typedef BOOST_DEDUCED_TYPENAME base::argument_type argument_type ; // Creates an optional<T> uninitialized. // No-throw optional() BOOST_NOEXCEPT : base() {} // Creates an optional<T> uninitialized. // No-throw optional( none_t none_ ) BOOST_NOEXCEPT : base(none_) {} // Creates an optional<T> initialized with 'val'. // Can throw if T::T(T const&) does optional ( argument_type val ) : base(optional_detail::init_value_tag(), val) {} // Creates an optional<T> initialized with 'move(val)'. // Can throw if T::T(T &&) does optional ( rval_reference_type val ) : base(optional_detail::init_value_tag(), optional_detail::forward<T>(val)) {} // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialized optional. // Can throw if T::T(T const&) does optional ( bool cond, argument_type val ) : base(cond,val) {} /// Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialized optional. // Can throw if T::T(T &&) does optional ( bool cond, rval_reference_type val ) : base( cond, optional_detail::forward<T>(val) ) {} // NOTE: MSVC needs templated versions first // Creates a deep copy of another convertible optional<U> // Requires a valid conversion from U to T. // Can throw if T::T(U const&) does template<class U> explicit optional ( optional<U> const& rhs #ifndef BOOST_OPTIONAL_DETAIL_NO_SFINAE_FRIENDLY_CONSTRUCTORS ,BOOST_DEDUCED_TYPENAME boost::enable_if< optional_detail::is_optional_constructible<T, U const&>, bool>::type = true #endif ) : base() { if ( rhs.is_initialized() ) this->construct(rhs.get()); } // Creates a deep move of another convertible optional<U> // Requires a valid conversion from U to T. // Can throw if T::T(U&&) does template<class U> explicit optional ( optional<U> && rhs #ifndef BOOST_OPTIONAL_DETAIL_NO_SFINAE_FRIENDLY_CONSTRUCTORS ,BOOST_DEDUCED_TYPENAME boost::enable_if< optional_detail::is_optional_constructible<T, U>, bool>::type = true #endif ) : base() { if ( rhs.is_initialized() ) this->construct( optional_detail::move(rhs.get()) ); } #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT // Creates an optional<T> with an expression which can be either // (a) An instance of InPlaceFactory (i.e. in_place(a,b,...,n); // (b) An instance of TypedInPlaceFactory ( i.e. in_place<T>(a,b,...,n); // (c) Any expression implicitly convertible to the single type // of a one-argument T's constructor. // (d*) Weak compilers (BCB) might also resolved Expr as optional<T> and optional<U> // even though explicit overloads are present for these. // Depending on the above some T ctor is called. // Can throw if the resolved T ctor throws. template<class Expr> explicit optional ( Expr&& expr, BOOST_DEDUCED_TYPENAME boost::enable_if< optional_detail::is_optional_val_init_candidate<T, Expr>, bool>::type = true ) : base(optional_detail::forward<Expr>(expr),boost::addressof(expr)) {} #endif // !defined BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT // Creates a deep copy of another optional<T> // Can throw if T::T(T const&) does #ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS optional ( optional const& ) = default; #else optional ( optional const& rhs ) : base( static_cast<base const&>(rhs) ) {} #endif // Creates a deep move of another optional<T> // Can throw if T::T(T&&) does #ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS optional ( optional && ) = default; #else optional ( optional && rhs ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value) : base( optional_detail::move(rhs) ) {} #endif #if BOOST_WORKAROUND(_MSC_VER, <= 1600) // On old MSVC compilers the implicitly declared dtor is not called ~optional() {} #endif #if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION) // Assigns from an expression. See corresponding constructor. // Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED template<class Expr> BOOST_DEDUCED_TYPENAME boost::enable_if<optional_detail::is_optional_val_assign_candidate<T, Expr>, optional&>::type operator= ( Expr&& expr ) { this->assign_expr(optional_detail::forward<Expr>(expr),boost::addressof(expr)); return *this ; } #endif // !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION) // Copy-assigns from another convertible optional<U> (converts && deep-copies the rhs value) // Requires a valid conversion from U to T. // Basic Guarantee: If T::T( U const& ) throws, this is left UNINITIALIZED template<class U> optional& operator= ( optional<U> const& rhs ) { this->assign(rhs); return *this ; } // Move-assigns from another convertible optional<U> (converts && deep-moves the rhs value) // Requires a valid conversion from U to T. // Basic Guarantee: If T::T( U && ) throws, this is left UNINITIALIZED template<class U> optional& operator= ( optional<U> && rhs ) { this->assign(optional_detail::move(rhs)); return *this ; } // Assigns from another optional<T> (deep-copies the rhs value) // Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED // (NOTE: On BCB, this operator is not actually called and left is left UNMODIFIED in case of a throw) #ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS optional& operator= ( optional const& rhs ) = default; #else optional& operator= ( optional const& rhs ) { this->assign( static_cast<base const&>(rhs) ) ; return *this ; } #endif // Assigns from another optional<T> (deep-moves the rhs value) #ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS optional& operator= ( optional && ) = default; #else optional& operator= ( optional && rhs ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value) { this->assign( static_cast<base &&>(rhs) ) ; return *this ; } #endif #ifndef BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX // Assigns from a T (deep-moves/copies the rhs value) template <typename T_> BOOST_DEDUCED_TYPENAME boost::enable_if<boost::is_same<T, BOOST_DEDUCED_TYPENAME boost::decay<T_>::type>, optional&>::type operator= ( T_&& val ) { this->assign( optional_detail::forward<T_>(val) ) ; return *this ; } #else // Assigns from a T (deep-copies the rhs value) // Basic Guarantee: If T::( T const& ) throws, this is left UNINITIALIZED optional& operator= ( argument_type val ) { this->assign( val ) ; return *this ; } // Assigns from a T (deep-moves the rhs value) optional& operator= ( rval_reference_type val ) { this->assign( optional_detail::move(val) ) ; return *this ; } #endif // BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX // Assigns from a "none" // Which destroys the current value, if any, leaving this UNINITIALIZED // No-throw (assuming T::~T() doesn't) optional& operator= ( none_t none_ ) BOOST_NOEXCEPT { this->assign( none_ ) ; return *this ; } // Constructs in-place // upon exception *this is always uninitialized template<class... Args> void emplace ( Args&&... args ) { this->emplace_assign( optional_detail::forward<Args>(args)... ); } template<class... Args> explicit optional ( in_place_init_t, Args&&... args ) : base( in_place_init, optional_detail::forward<Args>(args)... ) {} template<class... Args> explicit optional ( in_place_init_if_t, bool cond, Args&&... args ) : base( in_place_init_if, cond, optional_detail::forward<Args>(args)... ) {} void swap( optional & arg ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value) { // allow for Koenig lookup boost::core::invoke_swap(*this, arg); } // Returns a reference to the value if this is initialized, otherwise, // the behaviour is UNDEFINED // No-throw reference_const_type get() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); } reference_type get() { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); } // Returns a copy of the value if this is initialized, 'v' otherwise reference_const_type get_value_or ( reference_const_type v ) const { return this->is_initialized() ? get() : v ; } reference_type get_value_or ( reference_type v ) { return this->is_initialized() ? get() : v ; } // Returns a pointer to the value if this is initialized, otherwise, // the behaviour is UNDEFINED // No-throw pointer_const_type operator->() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; } pointer_type operator->() { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; } // Returns a reference to the value if this is initialized, otherwise, // the behaviour is UNDEFINED // No-throw reference_const_type operator *() BOOST_OPTIONAL_CONST_REF_QUAL { return this->get() ; } reference_type operator *() BOOST_OPTIONAL_REF_QUAL { return this->get() ; } #ifndef BOOST_NO_CXX11_REF_QUALIFIERS reference_type_of_temporary_wrapper operator *() && { return optional_detail::move(this->get()) ; } #endif reference_const_type value() BOOST_OPTIONAL_CONST_REF_QUAL { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } reference_type value() BOOST_OPTIONAL_REF_QUAL { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } template <class U> value_type value_or ( U&& v ) BOOST_OPTIONAL_CONST_REF_QUAL { if (this->is_initialized()) return get(); else return optional_detail::forward<U>(v); } template <typename F> value_type value_or_eval ( F f ) BOOST_OPTIONAL_CONST_REF_QUAL { if (this->is_initialized()) return get(); else return f(); } #ifndef BOOST_NO_CXX11_REF_QUALIFIERS reference_type_of_temporary_wrapper value() && { if (this->is_initialized()) return optional_detail::move(this->get()) ; else throw_exception(bad_optional_access()); } template <class U> value_type value_or ( U&& v ) && { if (this->is_initialized()) return optional_detail::move(get()); else return optional_detail::forward<U>(v); } template <typename F> value_type value_or_eval ( F f ) && { if (this->is_initialized()) return optional_detail::move(get()); else return f(); } #endif // Monadic interface template <typename F> optional<typename optional_detail::result_of<F, reference_type>::type> map(F f) BOOST_OPTIONAL_REF_QUAL { if (this->has_value()) return f(get()); else return none; } template <typename F> optional<typename optional_detail::result_of<F, reference_const_type>::type> map(F f) BOOST_OPTIONAL_CONST_REF_QUAL { if (this->has_value()) return f(get()); else return none; } #ifndef BOOST_NO_CXX11_REF_QUALIFIERS template <typename F> optional<typename optional_detail::result_of<F, reference_type_of_temporary_wrapper>::type> map(F f) && { if (this->has_value()) return f(optional_detail::move(this->get())); else return none; } #endif template <typename F> optional<typename optional_detail::result_value_type<F, reference_type>::type> flat_map(F f) BOOST_OPTIONAL_REF_QUAL { if (this->has_value()) return f(get()); else return none; } template <typename F> optional<typename optional_detail::result_value_type<F, reference_const_type>::type> flat_map(F f) BOOST_OPTIONAL_CONST_REF_QUAL { if (this->has_value()) return f(get()); else return none; } #ifndef BOOST_NO_CXX11_REF_QUALIFIERS template <typename F> optional<typename optional_detail::result_value_type<F, reference_type_of_temporary_wrapper>::type> flat_map(F f) && { if (this->has_value()) return f(optional_detail::move(get())); else return none; } #endif bool has_value() const BOOST_NOEXCEPT { return this->is_initialized() ; } explicit operator bool() const BOOST_NOEXCEPT { return this->has_value() ; } } ; template<class T> class optional<T&&> { static_assert(sizeof(T) == 0, "Optional rvalue references are illegal."); } ; } // namespace boost #ifndef BOOST_OPTIONAL_CONFIG_DONT_SPECIALIZE_OPTIONAL_REFS # include <boost/optional/detail/optional_reference_spec.hpp> #endif namespace boost { template<class T> inline optional<BOOST_DEDUCED_TYPENAME boost::decay<T>::type> make_optional ( T && v ) { return optional<BOOST_DEDUCED_TYPENAME boost::decay<T>::type>(optional_detail::forward<T>(v)); } // Returns optional<T>(cond,v) template<class T> inline optional<BOOST_DEDUCED_TYPENAME boost::decay<T>::type> make_optional ( bool cond, T && v ) { return optional<BOOST_DEDUCED_TYPENAME boost::decay<T>::type>(cond,optional_detail::forward<T>(v)); } // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED. // No-throw template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type get ( optional<T> const& opt ) { return opt.get() ; } template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::reference_type get ( optional<T>& opt ) { return opt.get() ; } // Returns a pointer to the value if this is initialized, otherwise, returns NULL. // No-throw template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::pointer_const_type get ( optional<T> const* opt ) { return opt->get_ptr() ; } template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::pointer_type get ( optional<T>* opt ) { return opt->get_ptr() ; } // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED. // No-throw template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type get_optional_value_or ( optional<T> const& opt, BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type v ) { return opt.get_value_or(v) ; } template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::reference_type get_optional_value_or ( optional<T>& opt, BOOST_DEDUCED_TYPENAME optional<T>::reference_type v ) { return opt.get_value_or(v) ; } // Returns a pointer to the value if this is initialized, otherwise, returns NULL. // No-throw template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::pointer_const_type get_pointer ( optional<T> const& opt ) { return opt.get_ptr() ; } template<class T> inline BOOST_DEDUCED_TYPENAME optional<T>::pointer_type get_pointer ( optional<T>& opt ) { return opt.get_ptr() ; } } // namespace boost #ifndef BOOST_NO_IOSTREAM namespace boost { // The following declaration prevents a bug where operator safe-bool is used upon streaming optional object if you forget the IO header. template<class CharType, class CharTrait> std::basic_ostream<CharType, CharTrait>& operator<<(std::basic_ostream<CharType, CharTrait>& os, optional_detail::optional_tag const&) { static_assert(sizeof(CharType) == 0, "If you want to output boost::optional, include header <boost/optional/optional_io.hpp>"); return os; } } // namespace boost #endif // BOOST_NO_IOSTREAM #include <boost/optional/detail/optional_relops.hpp> #include <boost/optional/detail/optional_swap.hpp> #endif // header guard