boost/optional/optional.hpp
// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal. // Copyright (C) 2014, 2015 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> #include <iosfwd> #include <boost/config.hpp> #include <boost/assert.hpp> #include <boost/core/addressof.hpp> #include <boost/core/enable_if.hpp> #include <boost/core/explicit_operator_bool.hpp> #include <boost/core/swap.hpp> #include <boost/optional/bad_optional_access.hpp> #include <boost/static_assert.hpp> #include <boost/throw_exception.hpp> #include <boost/type.hpp> #include <boost/type_traits/alignment_of.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_base_of.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_reference.hpp> #include <boost/type_traits/is_rvalue_reference.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/bool.hpp> #include <boost/mpl/not.hpp> #include <boost/detail/reference_content.hpp> #include <boost/move/utility.hpp> #include <boost/none.hpp> #include <boost/utility/compare_pointees.hpp> #include <boost/optional/optional_fwd.hpp> #if (defined BOOST_NO_CXX11_RVALUE_REFERENCES) || (defined BOOST_OPTIONAL_CONFIG_NO_RVALUE_REFERENCES) #define BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES #endif #if BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION,<=700) // AFAICT only Intel 7 correctly resolves the overload set // that includes the in-place factory taking functions, // so for the other icc versions, in-place factory support // is disabled #define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT #endif #if BOOST_WORKAROUND(__BORLANDC__, <= 0x551) // BCB (5.5.1) cannot parse the nested template struct in an inplace factory. #define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT #endif #if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) \ && BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581) ) // BCB (up to 5.64) has the following bug: // If there is a member function/operator template of the form // template<class Expr> mfunc( Expr expr ) ; // some calls are resolved to this even if there are other better matches. // The effect of this bug is that calls to converting ctors and assignments // are incrorrectly sink to this general catch-all member function template as shown above. #define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION #endif #if defined(__GNUC__) && !defined(__INTEL_COMPILER) // GCC since 3.3 has may_alias attribute that helps to alleviate optimizer issues with // regard to violation of the strict aliasing rules. The optional< T > storage type is marked // with this attribute in order to let the compiler know that it will alias objects of type T // and silence compilation warnings. #define BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS #endif // Daniel Wallin discovered that bind/apply.hpp badly interacts with the apply<> // member template of a factory as used in the optional<> implementation. // He proposed this simple fix which is to move the call to apply<> outside // namespace boost. namespace boost_optional_detail { template <class T, class Factory> inline void construct(Factory const& factory, void* address) { factory.BOOST_NESTED_TEMPLATE apply<T>(address); } } namespace boost { class in_place_factory_base ; class typed_in_place_factory_base ; // This forward is needed to refer to namespace scope swap from the member swap template<class T> void swap ( optional<T>& x, optional<T>& y ); namespace optional_detail { // This local class is used instead of that in "aligned_storage.hpp" // because I've found the 'official' class to ICE BCB5.5 // when some types are used with optional<> // (due to sizeof() passed down as a non-type template parameter) template <class T> class aligned_storage { // Borland ICEs if unnamed unions are used for this! union // This works around GCC warnings about breaking strict aliasing rules when casting storage address to T* #if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS) __attribute__((__may_alias__)) #endif dummy_u { char data[ sizeof(T) ]; BOOST_DEDUCED_TYPENAME type_with_alignment< ::boost::alignment_of<T>::value >::type aligner_; } dummy_ ; public: #if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS) void const* address() const { return &dummy_; } void * address() { return &dummy_; } #else void const* address() const { return dummy_.data; } void * address() { return dummy_.data; } #endif } ; template<class T> struct types_when_isnt_ref { typedef T const& reference_const_type ; typedef T & reference_type ; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES typedef T && rval_reference_type ; typedef T && reference_type_of_temporary_wrapper; #ifdef BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES // GCC 4.4 has support for an early draft of rvalue references. The conforming version below // causes warnings about returning references to a temporary. static T&& move(T&& r) { return r; } #else static rval_reference_type move(reference_type r) { return boost::move(r); } #endif #endif typedef T const* pointer_const_type ; typedef T * pointer_type ; typedef T const& argument_type ; } ; template<class T> struct types_when_is_ref { typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type raw_type ; typedef raw_type& reference_const_type ; typedef raw_type& reference_type ; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES typedef BOOST_DEDUCED_TYPENAME remove_const<raw_type>::type&& rval_reference_type ; typedef raw_type& reference_type_of_temporary_wrapper; static reference_type move(reference_type r) { return r; } #endif typedef raw_type* pointer_const_type ; typedef raw_type* pointer_type ; typedef raw_type& argument_type ; } ; template <class To, class From> void prevent_binding_rvalue_ref_to_optional_lvalue_ref() { #ifndef BOOST_OPTIONAL_CONFIG_ALLOW_BINDING_TO_RVALUES BOOST_STATIC_ASSERT_MSG( !boost::is_lvalue_reference<To>::value || !boost::is_rvalue_reference<From>::value, "binding rvalue references to optional lvalue references is disallowed"); #endif } struct optional_tag {} ; template<class T> class optional_base : public optional_tag { private : typedef #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) BOOST_DEDUCED_TYPENAME #endif ::boost::detail::make_reference_content<T>::type internal_type ; typedef aligned_storage<internal_type> storage_type ; typedef types_when_isnt_ref<T> types_when_not_ref ; typedef types_when_is_ref<T> types_when_ref ; typedef optional_base<T> this_type ; protected : typedef T value_type ; typedef mpl::true_ is_reference_tag ; typedef mpl::false_ is_not_reference_tag ; typedef BOOST_DEDUCED_TYPENAME is_reference<T>::type is_reference_predicate ; public: typedef BOOST_DEDUCED_TYPENAME mpl::if_<is_reference_predicate,types_when_ref,types_when_not_ref>::type types ; protected: typedef BOOST_DEDUCED_TYPENAME types::reference_type reference_type ; typedef BOOST_DEDUCED_TYPENAME types::reference_const_type reference_const_type ; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES typedef BOOST_DEDUCED_TYPENAME types::rval_reference_type rval_reference_type ; typedef BOOST_DEDUCED_TYPENAME types::reference_type_of_temporary_wrapper reference_type_of_temporary_wrapper ; #endif typedef BOOST_DEDUCED_TYPENAME types::pointer_type pointer_type ; typedef BOOST_DEDUCED_TYPENAME types::pointer_const_type pointer_const_type ; typedef BOOST_DEDUCED_TYPENAME types::argument_type 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 ( argument_type val ) : m_initialized(false) { construct(val); } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // move-construct an optional<T> initialized from an rvalue-ref to 'val'. // Can throw if T::T(T&&) does optional_base ( rval_reference_type val ) : m_initialized(false) { construct( boost::move(val) ); } #endif // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialzed 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 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()); } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Creates a deep move of another optional<T> // Can throw if T::T(T&&) does optional_base ( optional_base&& rhs ) : m_initialized(false) { if ( rhs.is_initialized() ) construct( boost::move(rhs.get_impl()) ); } #endif #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<class Expr, class PtrExpr> explicit optional_base ( Expr&& expr, PtrExpr const* tag ) : m_initialized(false) { construct(boost::forward<Expr>(expr),tag); } #else // This is used for both converting and in-place constructions. // Derived classes use the 'tag' to select the appropriate // implementation (the correct 'construct()' overload) template<class Expr> explicit optional_base ( Expr const& expr, Expr const* tag ) : m_initialized(false) { construct(expr,tag); } #endif // 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(), is_reference_predicate() ); else destroy(); } else { if ( rhs.is_initialized() ) construct(rhs.get_impl()); } } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Assigns from another optional<T> (deep-moves the rhs value) void assign ( optional_base&& rhs ) { if (is_initialized()) { if ( rhs.is_initialized() ) assign_value(boost::move(rhs.get_impl()), is_reference_predicate() ); else destroy(); } else { if ( rhs.is_initialized() ) construct(boost::move(rhs.get_impl())); } } #endif // 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(), is_reference_predicate() ); #else assign_value(static_cast<value_type>(rhs.get()), is_reference_predicate() ); #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 } } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // 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()), is_reference_predicate() ); else destroy(); } else { if ( rhs.is_initialized() ) construct(static_cast<ref_type>(rhs.get())); } } #endif // Assigns from a T (deep-copies the rhs value) void assign ( argument_type val ) { if (is_initialized()) assign_value(val, is_reference_predicate() ); else construct(val); } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Assigns from a T (deep-moves the rhs value) void assign ( rval_reference_type val ) { if (is_initialized()) assign_value( boost::move(val), is_reference_predicate() ); else construct( boost::move(val) ); } #endif // 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 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<class Expr, class ExprPtr> void assign_expr ( Expr&& expr, ExprPtr const* tag ) { if (is_initialized()) assign_expr_to_initialized(boost::forward<Expr>(expr),tag); else construct(boost::forward<Expr>(expr),tag); } #else template<class Expr> void assign_expr ( Expr const& expr, Expr const* tag ) { if (is_initialized()) assign_expr_to_initialized(expr,tag); else construct(expr,tag); } #endif #endif public : // **DEPPRECATED** Destroys the current value, if any, leaving this UNINITIALIZED // No-throw (assuming T::~T() doesn't) void reset() BOOST_NOEXCEPT { destroy(); } // **DEPPRECATED** 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 { return m_initialized ; } protected : void construct ( argument_type val ) { ::new (m_storage.address()) internal_type(val) ; m_initialized = true ; } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES void construct ( rval_reference_type val ) { ::new (m_storage.address()) internal_type( types::move(val) ) ; m_initialized = true ; } #endif #if (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) && (!defined BOOST_NO_CXX11_VARIADIC_TEMPLATES) // Constructs in-place // upon exception *this is always uninitialized template<class... Args> void emplace_assign ( Args&&... args ) { destroy(); ::new (m_storage.address()) internal_type( boost::forward<Args>(args)... ); m_initialized = true ; } #elif (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) template<class Arg> void emplace_assign ( Arg&& arg ) { destroy(); ::new (m_storage.address()) internal_type( boost::forward<Arg>(arg) ); m_initialized = true ; } void emplace_assign () { destroy(); ::new (m_storage.address()) internal_type(); m_initialized = true ; } #else template<class Arg> void emplace_assign ( const Arg& arg ) { destroy(); ::new (m_storage.address()) internal_type( arg ); m_initialized = true ; } template<class Arg> void emplace_assign ( Arg& arg ) { destroy(); ::new (m_storage.address()) internal_type( arg ); m_initialized = true ; } void emplace_assign () { destroy(); ::new (m_storage.address()) internal_type(); m_initialized = true ; } #endif #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Constructs in-place using the given factory template<class Expr> void construct ( Expr&& factory, in_place_factory_base const* ) { BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ; 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* ) { BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ; 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); } #else // Constructs in-place using the given factory template<class Expr> void construct ( Expr const& factory, in_place_factory_base const* ) { BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ; 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 const& factory, typed_in_place_factory_base const* ) { BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ; factory.apply(m_storage.address()) ; m_initialized = true ; } template<class Expr> void assign_expr_to_initialized ( Expr const& 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 const& factory, typed_in_place_factory_base const* tag ) { destroy(); construct(factory,tag); } #endif #endif #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // 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()) internal_type(boost::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(boost::forward<Expr>(expr), is_reference_predicate()); } #else // 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 const& expr, void const* ) { new (m_storage.address()) internal_type(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 const& expr, void const* ) { assign_value(expr, is_reference_predicate()); } #endif #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 dosen't work becasue the comnpiler issues and error // instead of choosing the wrong overload // #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // 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()) internal_type(types::move(expr.get())) ; m_initialized = true ; } } #else // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>) template<class Expr> void construct ( Expr const& 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()) internal_type(expr.get()) ; m_initialized = true ; } } #endif #endif // defined BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION void assign_value ( argument_type val, is_not_reference_tag ) { get_impl() = val; } void assign_value ( argument_type val, is_reference_tag ) { construct(val); } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES void assign_value ( rval_reference_type val, is_not_reference_tag ) { get_impl() = static_cast<rval_reference_type>(val); } void assign_value ( rval_reference_type val, is_reference_tag ) { construct( static_cast<rval_reference_type>(val) ); } #endif void destroy() { if ( m_initialized ) destroy_impl(is_reference_predicate()) ; } reference_const_type get_impl() const { return dereference(get_object(), is_reference_predicate() ) ; } reference_type get_impl() { return dereference(get_object(), is_reference_predicate() ) ; } pointer_const_type get_ptr_impl() const { return cast_ptr(get_object(), is_reference_predicate() ) ; } pointer_type get_ptr_impl() { return cast_ptr(get_object(), is_reference_predicate() ) ; } private : // internal_type can be either T or reference_content<T> #if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS) // This workaround is supposed to silence GCC warnings about broken strict aliasing rules internal_type const* get_object() const { union { void const* ap_pvoid; internal_type const* as_ptype; } caster = { m_storage.address() }; return caster.as_ptype; } internal_type * get_object() { union { void* ap_pvoid; internal_type* as_ptype; } caster = { m_storage.address() }; return caster.as_ptype; } #else internal_type const* get_object() const { return static_cast<internal_type const*>(m_storage.address()); } internal_type * get_object() { return static_cast<internal_type *> (m_storage.address()); } #endif // reference_content<T> lacks an implicit conversion to T&, so the following is needed to obtain a proper reference. reference_const_type dereference( internal_type const* p, is_not_reference_tag ) const { return *p ; } reference_type dereference( internal_type* p, is_not_reference_tag ) { return *p ; } reference_const_type dereference( internal_type const* p, is_reference_tag ) const { return p->get() ; } reference_type dereference( internal_type* p, is_reference_tag ) { return p->get() ; } #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581)) void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->internal_type::~internal_type() ; m_initialized = false ; } #else void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->~T() ; m_initialized = false ; } #endif void destroy_impl ( is_reference_tag ) { m_initialized = false ; } // If T is of reference type, trying to get a pointer to the held value must result in a compile-time error. // Decent compilers should disallow conversions from reference_content<T>* to T*, but just in case, // the following olverloads are used to filter out the case and guarantee an error in case of T being a reference. pointer_const_type cast_ptr( internal_type const* p, is_not_reference_tag ) const { return p ; } pointer_type cast_ptr( internal_type * p, is_not_reference_tag ) { return p ; } pointer_const_type cast_ptr( internal_type const* p, is_reference_tag ) const { return &p->get() ; } pointer_type cast_ptr( internal_type * p, is_reference_tag ) { return &p->get() ; } bool m_initialized ; storage_type m_storage ; } ; } // namespace optional_detail template<class T> class optional : public optional_detail::optional_base<T> { typedef optional_detail::optional_base<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 ; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES 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 ; #endif 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(val) {} #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Creates an optional<T> initialized with 'move(val)'. // Can throw if T::T(T &&) does optional ( rval_reference_type val ) : base( boost::forward<T>(val) ) {optional_detail::prevent_binding_rvalue_ref_to_optional_lvalue_ref<T, rval_reference_type>();} #endif // 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) {} // 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 ) : base() { if ( rhs.is_initialized() ) this->construct(rhs.get()); } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // 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 ) : base() { if ( rhs.is_initialized() ) this->construct( boost::move(rhs.get()) ); } #endif #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. #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<class Expr> explicit optional ( Expr&& expr, BOOST_DEDUCED_TYPENAME boost::disable_if_c< (boost::is_base_of<optional_detail::optional_tag, BOOST_DEDUCED_TYPENAME boost::decay<Expr>::type>::value) || boost::is_same<BOOST_DEDUCED_TYPENAME boost::decay<Expr>::type, none_t>::value >::type* = 0 ) : base(boost::forward<Expr>(expr),boost::addressof(expr)) {optional_detail::prevent_binding_rvalue_ref_to_optional_lvalue_ref<T, Expr&&>();} #else template<class Expr> explicit optional ( Expr const& expr ) : base(expr,boost::addressof(expr)) {} #endif // !defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES #endif // !defined BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT // Creates a deep copy of another optional<T> // Can throw if T::T(T const&) does optional ( optional const& rhs ) : base( static_cast<base const&>(rhs) ) {} #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Creates a deep move of another optional<T> // Can throw if T::T(T&&) does optional ( optional && rhs ) BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value) : base( boost::move(rhs) ) {} #endif // No-throw (assuming T::~T() doesn't) ~optional() {} #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 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<class Expr> BOOST_DEDUCED_TYPENAME boost::disable_if_c< boost::is_base_of<optional_detail::optional_tag, BOOST_DEDUCED_TYPENAME boost::decay<Expr>::type>::value || boost::is_same<BOOST_DEDUCED_TYPENAME boost::decay<Expr>::type, none_t>::value, optional& >::type operator= ( Expr&& expr ) { optional_detail::prevent_binding_rvalue_ref_to_optional_lvalue_ref<T, Expr&&>(); this->assign_expr(boost::forward<Expr>(expr),boost::addressof(expr)); return *this ; } #else template<class Expr> optional& operator= ( Expr const& expr ) { this->assign_expr(expr,boost::addressof(expr)); return *this ; } #endif // !defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES #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 ; } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // 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(boost::move(rhs)); return *this ; } #endif // 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) optional& operator= ( optional const& rhs ) { this->assign( static_cast<base const&>(rhs) ) ; return *this ; } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Assigns from another optional<T> (deep-moves the rhs value) 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 // 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 ; } #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES // Assigns from a T (deep-moves the rhs value) optional& operator= ( rval_reference_type val ) { optional_detail::prevent_binding_rvalue_ref_to_optional_lvalue_ref<T, rval_reference_type>(); this->assign( boost::move(val) ) ; return *this ; } #endif // 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 ; } #if (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) && (!defined BOOST_NO_CXX11_VARIADIC_TEMPLATES) // Constructs in-place // upon exception *this is always uninitialized template<class... Args> void emplace ( Args&&... args ) { this->emplace_assign( boost::forward<Args>(args)... ); } #elif (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) template<class Arg> void emplace ( Arg&& arg ) { this->emplace_assign( boost::forward<Arg>(arg) ); } void emplace () { this->emplace_assign(); } #else template<class Arg> void emplace ( const Arg& arg ) { this->emplace_assign( arg ); } template<class Arg> void emplace ( Arg& arg ) { this->emplace_assign( arg ); } void emplace () { this->emplace_assign(); } #endif 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::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 #if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) reference_const_type operator *() const& { return this->get() ; } reference_type operator *() & { return this->get() ; } reference_type_of_temporary_wrapper operator *() && { return base::types::move(this->get()) ; } #else reference_const_type operator *() const { return this->get() ; } reference_type operator *() { return this->get() ; } #endif // !defined BOOST_NO_CXX11_REF_QUALIFIERS #if (!defined BOOST_NO_CXX11_REF_QUALIFIERS) && (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) reference_const_type value() const& { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } reference_type value() & { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } reference_type_of_temporary_wrapper value() && { if (this->is_initialized()) return base::types::move(this->get()) ; else throw_exception(bad_optional_access()); } #else reference_const_type value() const { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } reference_type value() { if (this->is_initialized()) return this->get() ; else throw_exception(bad_optional_access()); } #endif #ifndef BOOST_NO_CXX11_REF_QUALIFIERS template <class U> value_type value_or ( U&& v ) const& { if (this->is_initialized()) return get(); else return boost::forward<U>(v); } template <class U> value_type value_or ( U&& v ) && { if (this->is_initialized()) return base::types::move(get()); else return boost::forward<U>(v); } #elif !defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template <class U> value_type value_or ( U&& v ) const { if (this->is_initialized()) return get(); else return boost::forward<U>(v); } #else template <class U> value_type value_or ( U const& v ) const { if (this->is_initialized()) return get(); else return v; } template <class U> value_type value_or ( U& v ) const { if (this->is_initialized()) return get(); else return v; } #endif #ifndef BOOST_NO_CXX11_REF_QUALIFIERS template <typename F> value_type value_or_eval ( F f ) const& { if (this->is_initialized()) return get(); else return f(); } template <typename F> value_type value_or_eval ( F f ) && { if (this->is_initialized()) return base::types::move(get()); else return f(); } #else template <typename F> value_type value_or_eval ( F f ) const { if (this->is_initialized()) return get(); else return f(); } #endif bool operator!() const BOOST_NOEXCEPT { return !this->is_initialized() ; } BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT() } ; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<class T> class optional<T&&> { BOOST_STATIC_ASSERT_MSG(sizeof(T) == 0, "Optional rvalue references are illegal."); } ; #endif // Returns optional<T>(v) template<class T> inline optional<T> make_optional ( T const& v ) { return optional<T>(v); } // Returns optional<T>(cond,v) template<class T> inline optional<T> make_optional ( bool cond, T const& v ) { return optional<T>(cond,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() ; } // 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&) { BOOST_STATIC_ASSERT_MSG(sizeof(CharType) == 0, "If you want to output boost::optional, include header <boost/optional/optional_io.hpp>"); return os; } // optional's relational operators ( ==, !=, <, >, <=, >= ) have deep-semantics (compare values). // WARNING: This is UNLIKE pointers. Use equal_pointees()/less_pointess() in generic code instead. // // optional<T> vs optional<T> cases // template<class T> inline bool operator == ( optional<T> const& x, optional<T> const& y ) { return equal_pointees(x,y); } template<class T> inline bool operator < ( optional<T> const& x, optional<T> const& y ) { return less_pointees(x,y); } template<class T> inline bool operator != ( optional<T> const& x, optional<T> const& y ) { return !( x == y ) ; } template<class T> inline bool operator > ( optional<T> const& x, optional<T> const& y ) { return y < x ; } template<class T> inline bool operator <= ( optional<T> const& x, optional<T> const& y ) { return !( y < x ) ; } template<class T> inline bool operator >= ( optional<T> const& x, optional<T> const& y ) { return !( x < y ) ; } // // optional<T> vs T cases // template<class T> inline bool operator == ( optional<T> const& x, T const& y ) { return equal_pointees(x, optional<T>(y)); } template<class T> inline bool operator < ( optional<T> const& x, T const& y ) { return less_pointees(x, optional<T>(y)); } template<class T> inline bool operator != ( optional<T> const& x, T const& y ) { return !( x == y ) ; } template<class T> inline bool operator > ( optional<T> const& x, T const& y ) { return y < x ; } template<class T> inline bool operator <= ( optional<T> const& x, T const& y ) { return !( y < x ) ; } template<class T> inline bool operator >= ( optional<T> const& x, T const& y ) { return !( x < y ) ; } // // T vs optional<T> cases // template<class T> inline bool operator == ( T const& x, optional<T> const& y ) { return equal_pointees( optional<T>(x), y ); } template<class T> inline bool operator < ( T const& x, optional<T> const& y ) { return less_pointees( optional<T>(x), y ); } template<class T> inline bool operator != ( T const& x, optional<T> const& y ) { return !( x == y ) ; } template<class T> inline bool operator > ( T const& x, optional<T> const& y ) { return y < x ; } template<class T> inline bool operator <= ( T const& x, optional<T> const& y ) { return !( y < x ) ; } template<class T> inline bool operator >= ( T const& x, optional<T> const& y ) { return !( x < y ) ; } // // optional<T> vs none cases // template<class T> inline bool operator == ( optional<T> const& x, none_t ) BOOST_NOEXCEPT { return !x; } template<class T> inline bool operator < ( optional<T> const& x, none_t ) { return less_pointees(x,optional<T>() ); } template<class T> inline bool operator != ( optional<T> const& x, none_t ) BOOST_NOEXCEPT { return bool(x); } template<class T> inline bool operator > ( optional<T> const& x, none_t y ) { return y < x ; } template<class T> inline bool operator <= ( optional<T> const& x, none_t y ) { return !( y < x ) ; } template<class T> inline bool operator >= ( optional<T> const& x, none_t y ) { return !( x < y ) ; } // // none vs optional<T> cases // template<class T> inline bool operator == ( none_t , optional<T> const& y ) BOOST_NOEXCEPT { return !y; } template<class T> inline bool operator < ( none_t , optional<T> const& y ) { return less_pointees(optional<T>() ,y); } template<class T> inline bool operator != ( none_t, optional<T> const& y ) BOOST_NOEXCEPT { return bool(y); } template<class T> inline bool operator > ( none_t x, optional<T> const& y ) { return y < x ; } template<class T> inline bool operator <= ( none_t x, optional<T> const& y ) { return !( y < x ) ; } template<class T> inline bool operator >= ( none_t x, optional<T> const& y ) { return !( x < y ) ; } namespace optional_detail { template<bool use_default_constructor> struct swap_selector; template<> struct swap_selector<true> { template<class T> static void optional_swap ( optional<T>& x, optional<T>& y ) { const bool hasX = !!x; const bool hasY = !!y; if ( !hasX && !hasY ) return; if( !hasX ) x.emplace(); else if ( !hasY ) y.emplace(); // Boost.Utility.Swap will take care of ADL and workarounds for broken compilers boost::swap(x.get(),y.get()); if( !hasX ) y = boost::none ; else if( !hasY ) x = boost::none ; } }; #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES template<> struct swap_selector<false> { template<class T> static void optional_swap ( optional<T>& x, optional<T>& y ) //BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && BOOST_NOEXCEPT_EXPR(boost::swap(*x, *y))) { if(x) { if (y) { boost::swap(*x, *y); } else { y = boost::move(*x); x = boost::none; } } else { if (y) { x = boost::move(*y); y = boost::none; } } } }; #else template<> struct swap_selector<false> { template<class T> static void optional_swap ( optional<T>& x, optional<T>& y ) { const bool hasX = !!x; const bool hasY = !!y; if ( !hasX && hasY ) { x = y.get(); y = boost::none ; } else if ( hasX && !hasY ) { y = x.get(); x = boost::none ; } else if ( hasX && hasY ) { // Boost.Utility.Swap will take care of ADL and workarounds for broken compilers boost::swap(x.get(),y.get()); } } }; #endif // !defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES } // namespace optional_detail #if (!defined BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined BOOST_CONFIG_RESTORE_OBSOLETE_SWAP_IMPLEMENTATION) template<class T> struct optional_swap_should_use_default_constructor : boost::false_type {} ; #else template<class T> struct optional_swap_should_use_default_constructor : has_nothrow_default_constructor<T> {} ; #endif //BOOST_NO_CXX11_RVALUE_REFERENCES template<class T> inline void swap ( optional<T>& x, optional<T>& y ) //BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && BOOST_NOEXCEPT_EXPR(boost::swap(*x, *y))) { optional_detail::swap_selector<optional_swap_should_use_default_constructor<T>::value>::optional_swap(x, y); } } // namespace boost #endif