sl@0: // Copyright (C) 2003, Fernando Luis Cacciola Carballal.
sl@0: //
sl@0: // Use, modification, and distribution is subject to the Boost Software
sl@0: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: //
sl@0: // See http://www.boost.org/lib/optional for documentation.
sl@0: //
sl@0: // You are welcome to contact the author at:
sl@0: //  fernando_cacciola@hotmail.com
sl@0: //
sl@0: #ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
sl@0: #define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
sl@0: 
sl@0: #include<new>
sl@0: #include<algorithm>
sl@0: 
sl@0: #include "boost/config.hpp"
sl@0: #include "boost/assert.hpp"
sl@0: #include "boost/type.hpp"
sl@0: #include "boost/type_traits/alignment_of.hpp"
sl@0: #include "boost/type_traits/type_with_alignment.hpp"
sl@0: #include "boost/type_traits/remove_reference.hpp"
sl@0: #include "boost/type_traits/is_reference.hpp"
sl@0: #include "boost/mpl/if.hpp"
sl@0: #include "boost/mpl/bool.hpp"
sl@0: #include "boost/mpl/not.hpp"
sl@0: #include "boost/detail/reference_content.hpp"
sl@0: #include "boost/none.hpp"
sl@0: #include "boost/utility/compare_pointees.hpp"
sl@0: 
sl@0: #include "boost/optional/optional_fwd.hpp"
sl@0: 
sl@0: #if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
sl@0: // VC6.0 has the following bug:
sl@0: //   When a templated assignment operator exist, an implicit conversion
sl@0: //   constructing an optional<T> is used when assigment of the form:
sl@0: //     optional<T> opt ; opt = T(...);
sl@0: //   is compiled.
sl@0: //   However, optional's ctor is _explicit_ and the assignemt shouldn't compile.
sl@0: //   Therefore, for VC6.0 templated assignment is disabled.
sl@0: //
sl@0: #define BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
sl@0: #endif
sl@0: 
sl@0: #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
sl@0: // VC7.0 has the following bug:
sl@0: //   When both a non-template and a template copy-ctor exist
sl@0: //   and the templated version is made 'explicit', the explicit is also
sl@0: //   given to the non-templated version, making the class non-implicitely-copyable.
sl@0: //
sl@0: #define BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR
sl@0: #endif
sl@0: 
sl@0: #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION,<=700)
sl@0: // AFAICT only VC7.1 correctly resolves the overload set
sl@0: // that includes the in-place factory taking functions,
sl@0: // so for the other VC versions, in-place factory support
sl@0: // is disabled
sl@0: #define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
sl@0: #endif
sl@0: 
sl@0: #if BOOST_WORKAROUND(__BORLANDC__, <= 0x551)
sl@0: // BCB (5.5.1) cannot parse the nested template struct in an inplace factory.
sl@0: #define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
sl@0: #endif
sl@0: 
sl@0: #if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) \
sl@0:     && BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581) )
sl@0: // BCB (up to 5.64) has the following bug:
sl@0: //   If there is a member function/operator template of the form
sl@0: //     template<class Expr> mfunc( Expr expr ) ;
sl@0: //   some calls are resolved to this even if there are other better matches.
sl@0: //   The effect of this bug is that calls to converting ctors and assignments
sl@0: //   are incrorrectly sink to this general catch-all member function template as shown above.
sl@0: #define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
sl@0: #endif
sl@0: 
sl@0: // Daniel Wallin discovered that bind/apply.hpp badly interacts with the apply<>
sl@0: // member template of a factory as used in the optional<> implementation.
sl@0: // He proposed this simple fix which is to move the call to apply<> outside
sl@0: // namespace boost.
sl@0: namespace boost_optional_detail
sl@0: {
sl@0:   template <class T, class Factory>
sl@0:   void construct(Factory const& factory, void* address)
sl@0:   {
sl@0:     factory.BOOST_NESTED_TEMPLATE apply<T>(address);
sl@0:   }
sl@0: }
sl@0: 
sl@0: 
sl@0: namespace boost {
sl@0: 
sl@0: class in_place_factory_base ;
sl@0: class typed_in_place_factory_base ;
sl@0: 
sl@0: namespace optional_detail {
sl@0: 
sl@0: // This local class is used instead of that in "aligned_storage.hpp"
sl@0: // because I've found the 'official' class to ICE BCB5.5
sl@0: // when some types are used with optional<>
sl@0: // (due to sizeof() passed down as a non-type template parameter)
sl@0: template <class T>
sl@0: class aligned_storage
sl@0: {
sl@0:     // Borland ICEs if unnamed unions are used for this!
sl@0:     union dummy_u
sl@0:     {
sl@0:         char data[ sizeof(T) ];
sl@0:         BOOST_DEDUCED_TYPENAME type_with_alignment<
sl@0:           ::boost::alignment_of<T>::value >::type aligner_;
sl@0:     } dummy_ ;
sl@0: 
sl@0:   public:
sl@0: 
sl@0:     void const* address() const { return &dummy_.data[0]; }
sl@0:     void      * address()       { return &dummy_.data[0]; }
sl@0: } ;
sl@0: 
sl@0: template<class T>
sl@0: struct types_when_isnt_ref
sl@0: {
sl@0:   typedef T const& reference_const_type ;
sl@0:   typedef T &      reference_type ;
sl@0:   typedef T const* pointer_const_type ;
sl@0:   typedef T *      pointer_type ;
sl@0:   typedef T const& argument_type ;
sl@0: } ;
sl@0: template<class T>
sl@0: struct types_when_is_ref
sl@0: {
sl@0:   typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type raw_type ;
sl@0: 
sl@0:   typedef raw_type& reference_const_type ;
sl@0:   typedef raw_type& reference_type ;
sl@0:   typedef raw_type* pointer_const_type ;
sl@0:   typedef raw_type* pointer_type ;
sl@0:   typedef raw_type& argument_type ;
sl@0: } ;
sl@0: 
sl@0: struct optional_tag {} ;
sl@0: 
sl@0: template<class T>
sl@0: class optional_base : public optional_tag
sl@0: {
sl@0:   private :
sl@0: 
sl@0:     typedef
sl@0: #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
sl@0:     BOOST_DEDUCED_TYPENAME
sl@0: #endif 
sl@0:     ::boost::detail::make_reference_content<T>::type internal_type ;
sl@0: 
sl@0:     typedef aligned_storage<internal_type> storage_type ;
sl@0: 
sl@0:     typedef types_when_isnt_ref<T> types_when_not_ref ;
sl@0:     typedef types_when_is_ref<T>   types_when_ref   ;
sl@0: 
sl@0:     typedef optional_base<T> this_type ;
sl@0: 
sl@0:   protected :
sl@0: 
sl@0:     typedef T value_type ;
sl@0: 
sl@0:     typedef mpl::true_  is_reference_tag ;
sl@0:     typedef mpl::false_ is_not_reference_tag ;
sl@0: 
sl@0:     typedef BOOST_DEDUCED_TYPENAME is_reference<T>::type is_reference_predicate ;
sl@0: 
sl@0:     typedef BOOST_DEDUCED_TYPENAME mpl::if_<is_reference_predicate,types_when_ref,types_when_not_ref>::type types ;
sl@0: 
sl@0:     typedef bool (this_type::*unspecified_bool_type)() const;
sl@0: 
sl@0:     typedef BOOST_DEDUCED_TYPENAME types::reference_type       reference_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME types::reference_const_type reference_const_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME types::pointer_type         pointer_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME types::pointer_const_type   pointer_const_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME types::argument_type        argument_type ;
sl@0: 
sl@0:     // Creates an optional<T> uninitialized.
sl@0:     // No-throw
sl@0:     optional_base()
sl@0:       :
sl@0:       m_initialized(false) {}
sl@0: 
sl@0:     // Creates an optional<T> uninitialized.
sl@0:     // No-throw
sl@0:     optional_base ( none_t )
sl@0:       :
sl@0:       m_initialized(false) {}
sl@0: 
sl@0:     // Creates an optional<T> initialized with 'val'.
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional_base ( argument_type val )
sl@0:       :
sl@0:       m_initialized(false)
sl@0:     {
sl@0:       construct(val);
sl@0:     }
sl@0:     
sl@0:     // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialzed optional<T>.
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional_base ( bool cond, argument_type val )
sl@0:       :
sl@0:       m_initialized(false)
sl@0:     {
sl@0:       if ( cond )
sl@0:         construct(val);
sl@0:     }
sl@0: 
sl@0:     // Creates a deep copy of another optional<T>
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional_base ( optional_base const& rhs )
sl@0:       :
sl@0:       m_initialized(false)
sl@0:     {
sl@0:       if ( rhs.is_initialized() )
sl@0:         construct(rhs.get_impl());
sl@0:     }
sl@0: 
sl@0: 
sl@0:     // This is used for both converting and in-place constructions.
sl@0:     // Derived classes use the 'tag' to select the appropriate
sl@0:     // implementation (the correct 'construct()' overload)
sl@0:     template<class Expr>
sl@0:     explicit optional_base ( Expr const& expr, Expr const* tag )
sl@0:       :
sl@0:       m_initialized(false)
sl@0:     {
sl@0:       construct(expr,tag);
sl@0:     }
sl@0: 
sl@0: 
sl@0: 
sl@0:     // No-throw (assuming T::~T() doesn't)
sl@0:     ~optional_base() { destroy() ; }
sl@0: 
sl@0:     // Assigns from another optional<T> (deep-copies the rhs value)
sl@0:     void assign ( optional_base const& rhs )
sl@0:     {
sl@0:       if (is_initialized())
sl@0:       {
sl@0:         if ( rhs.is_initialized() )
sl@0:              assign_value(rhs.get_impl(), is_reference_predicate() );
sl@0:         else destroy();
sl@0:       }
sl@0:       else
sl@0:       {
sl@0:         if ( rhs.is_initialized() )
sl@0:           construct(rhs.get_impl());
sl@0:       }
sl@0:     }
sl@0: 
sl@0:     // Assigns from another _convertible_ optional<U> (deep-copies the rhs value)
sl@0:     template<class U>
sl@0:     void assign ( optional<U> const& rhs )
sl@0:     {
sl@0:       if (is_initialized())
sl@0:       {
sl@0:         if ( rhs.is_initialized() )
sl@0:              assign_value(static_cast<value_type>(rhs.get()), is_reference_predicate() );
sl@0:         else destroy();
sl@0:       }
sl@0:       else
sl@0:       {
sl@0:         if ( rhs.is_initialized() )
sl@0:           construct(static_cast<value_type>(rhs.get()));
sl@0:       }
sl@0:     }
sl@0: 
sl@0:     // Assigns from a T (deep-copies the rhs value)
sl@0:     void assign ( argument_type val )
sl@0:     {
sl@0:       if (is_initialized())
sl@0:            assign_value(val, is_reference_predicate() );
sl@0:       else construct(val);
sl@0:     }
sl@0: 
sl@0:     // Assigns from "none", destroying the current value, if any, leaving this UNINITIALIZED
sl@0:     // No-throw (assuming T::~T() doesn't)
sl@0:     void assign ( none_t ) { destroy(); }
sl@0: 
sl@0: #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
sl@0:     template<class Expr>
sl@0:     void assign_expr ( Expr const& expr, Expr const* tag )
sl@0:       {
sl@0:         if (is_initialized())
sl@0:              assign_expr_to_initialized(expr,tag);
sl@0:         else construct(expr,tag);
sl@0:       }
sl@0: #endif
sl@0: 
sl@0:   public :
sl@0: 
sl@0:     // Destroys the current value, if any, leaving this UNINITIALIZED
sl@0:     // No-throw (assuming T::~T() doesn't)
sl@0:     void reset() { destroy(); }
sl@0: 
sl@0:     // Replaces the current value -if any- with 'val'
sl@0:     void reset ( argument_type val ) { assign(val); }
sl@0: 
sl@0:     // Returns a pointer to the value if this is initialized, otherwise,
sl@0:     // returns NULL.
sl@0:     // No-throw
sl@0:     pointer_const_type get_ptr() const { return m_initialized ? get_ptr_impl() : 0 ; }
sl@0:     pointer_type       get_ptr()       { return m_initialized ? get_ptr_impl() : 0 ; }
sl@0: 
sl@0:     bool is_initialized() const { return m_initialized ; }
sl@0: 
sl@0:   protected :
sl@0: 
sl@0:     void construct ( argument_type val )
sl@0:      {
sl@0:        new (m_storage.address()) internal_type(val) ;
sl@0:        m_initialized = true ;
sl@0:      }
sl@0: 
sl@0: #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
sl@0:     // Constructs in-place using the given factory
sl@0:     template<class Expr>
sl@0:     void construct ( Expr const& factory, in_place_factory_base const* )
sl@0:      {
sl@0:        BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ;
sl@0:        boost_optional_detail::construct<value_type>(factory, m_storage.address());
sl@0:        m_initialized = true ;
sl@0:      }
sl@0: 
sl@0:     // Constructs in-place using the given typed factory
sl@0:     template<class Expr>
sl@0:     void construct ( Expr const& factory, typed_in_place_factory_base const* )
sl@0:      {
sl@0:        BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ;
sl@0:        factory.apply(m_storage.address()) ;
sl@0:        m_initialized = true ;
sl@0:      }
sl@0: 
sl@0:     template<class Expr>
sl@0:     void assign_expr_to_initialized ( Expr const& factory, in_place_factory_base const* tag )
sl@0:      {
sl@0:        destroy();
sl@0:        construct(factory,tag);
sl@0:      }
sl@0: 
sl@0:     // Constructs in-place using the given typed factory
sl@0:     template<class Expr>
sl@0:     void assign_expr_to_initialized ( Expr const& factory, typed_in_place_factory_base const* tag )
sl@0:      {
sl@0:        destroy();
sl@0:        construct(factory,tag);
sl@0:      }
sl@0: #endif
sl@0: 
sl@0:     // Constructs using any expression implicitely convertible to the single argument
sl@0:     // of a one-argument T constructor.
sl@0:     // Converting constructions of optional<T> from optional<U> uses this function with
sl@0:     // 'Expr' being of type 'U' and relying on a converting constructor of T from U.
sl@0:     template<class Expr>
sl@0:     void construct ( Expr const& expr, void const* )
sl@0:      {
sl@0:        new (m_storage.address()) internal_type(expr) ;
sl@0:        m_initialized = true ;
sl@0:      }
sl@0: 
sl@0:     // Assigns using a form any expression implicitely convertible to the single argument
sl@0:     // of a T's assignment operator.
sl@0:     // Converting assignments of optional<T> from optional<U> uses this function with
sl@0:     // 'Expr' being of type 'U' and relying on a converting assignment of T from U.
sl@0:     template<class Expr>
sl@0:     void assign_expr_to_initialized ( Expr const& expr, void const* )
sl@0:      {
sl@0:        assign_value(expr, is_reference_predicate());
sl@0:      }
sl@0: 
sl@0: #ifdef BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
sl@0:     // BCB5.64 (and probably lower versions) workaround.
sl@0:     //   The in-place factories are supported by means of catch-all constructors
sl@0:     //   and assignment operators (the functions are parameterized in terms of
sl@0:     //   an arbitrary 'Expr' type)
sl@0:     //   This compiler incorrectly resolves the overload set and sinks optional<T> and optional<U>
sl@0:     //   to the 'Expr'-taking functions even though explicit overloads are present for them.
sl@0:     //   Thus, the following overload is needed to properly handle the case when the 'lhs'
sl@0:     //   is another optional.
sl@0:     //
sl@0:     // For VC<=70 compilers this workaround dosen't work becasue the comnpiler issues and error
sl@0:     // instead of choosing the wrong overload
sl@0:     //
sl@0:     // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>)
sl@0:     template<class Expr>
sl@0:     void construct ( Expr const& expr, optional_tag const* )
sl@0:      {
sl@0:        if ( expr.is_initialized() )
sl@0:        {
sl@0:          // An exception can be thrown here.
sl@0:          // It it happens, THIS will be left uninitialized.
sl@0:          new (m_storage.address()) internal_type(expr.get()) ;
sl@0:          m_initialized = true ;
sl@0:        }
sl@0:      }
sl@0: #endif
sl@0: 
sl@0:     void assign_value ( argument_type val, is_not_reference_tag ) { get_impl() = val; }
sl@0:     void assign_value ( argument_type val, is_reference_tag     ) { construct(val); }
sl@0: 
sl@0:     void destroy()
sl@0:     {
sl@0:       if ( m_initialized )
sl@0:         destroy_impl(is_reference_predicate()) ;
sl@0:     }
sl@0: 
sl@0:     unspecified_bool_type safe_bool() const { return m_initialized ? &this_type::is_initialized : 0 ; }
sl@0: 
sl@0:     reference_const_type get_impl() const { return dereference(get_object(), is_reference_predicate() ) ; }
sl@0:     reference_type       get_impl()       { return dereference(get_object(), is_reference_predicate() ) ; }
sl@0: 
sl@0:     pointer_const_type get_ptr_impl() const { return cast_ptr(get_object(), is_reference_predicate() ) ; }
sl@0:     pointer_type       get_ptr_impl()       { return cast_ptr(get_object(), is_reference_predicate() ) ; }
sl@0: 
sl@0:   private :
sl@0: 
sl@0:     // internal_type can be either T or reference_content<T>
sl@0:     internal_type const* get_object() const { return static_cast<internal_type const*>(m_storage.address()); }
sl@0:     internal_type *      get_object()       { return static_cast<internal_type *>     (m_storage.address()); }
sl@0: 
sl@0:     // reference_content<T> lacks an implicit conversion to T&, so the following is needed to obtain a proper reference.
sl@0:     reference_const_type dereference( internal_type const* p, is_not_reference_tag ) const { return *p ; }
sl@0:     reference_type       dereference( internal_type*       p, is_not_reference_tag )       { return *p ; }
sl@0:     reference_const_type dereference( internal_type const* p, is_reference_tag     ) const { return p->get() ; }
sl@0:     reference_type       dereference( internal_type*       p, is_reference_tag     )       { return p->get() ; }
sl@0: 
sl@0: #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581))
sl@0:     void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->internal_type::~internal_type() ; m_initialized = false ; }
sl@0: #else
sl@0:     void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->T::~T() ; m_initialized = false ; }
sl@0: #endif
sl@0: 
sl@0:     void destroy_impl ( is_reference_tag     ) { m_initialized = false ; }
sl@0: 
sl@0:     // If T is of reference type, trying to get a pointer to the held value must result in a compile-time error.
sl@0:     // Decent compilers should disallow conversions from reference_content<T>* to T*, but just in case,
sl@0:     // the following olverloads are used to filter out the case and guarantee an error in case of T being a reference.
sl@0:     pointer_const_type cast_ptr( internal_type const* p, is_not_reference_tag ) const { return p ; }
sl@0:     pointer_type       cast_ptr( internal_type *      p, is_not_reference_tag )       { return p ; }
sl@0:     pointer_const_type cast_ptr( internal_type const* p, is_reference_tag     ) const { return &p->get() ; }
sl@0:     pointer_type       cast_ptr( internal_type *      p, is_reference_tag     )       { return &p->get() ; }
sl@0: 
sl@0:     bool m_initialized ;
sl@0:     storage_type m_storage ;
sl@0: } ;
sl@0: 
sl@0: } // namespace optional_detail
sl@0: 
sl@0: template<class T>
sl@0: class optional : public optional_detail::optional_base<T>
sl@0: {
sl@0:     typedef optional_detail::optional_base<T> base ;
sl@0: 
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::unspecified_bool_type  unspecified_bool_type ;
sl@0: 
sl@0:   public :
sl@0: 
sl@0:     typedef optional<T> this_type ;
sl@0: 
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::value_type           value_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::reference_type       reference_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::reference_const_type reference_const_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::pointer_type         pointer_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::pointer_const_type   pointer_const_type ;
sl@0:     typedef BOOST_DEDUCED_TYPENAME base::argument_type        argument_type ;
sl@0: 
sl@0:     // Creates an optional<T> uninitialized.
sl@0:     // No-throw
sl@0:     optional() : base() {}
sl@0: 
sl@0:     // Creates an optional<T> uninitialized.
sl@0:     // No-throw
sl@0:     optional( none_t none_ ) : base(none_) {}
sl@0: 
sl@0:     // Creates an optional<T> initialized with 'val'.
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional ( argument_type val ) : base(val) {}
sl@0: 
sl@0:     // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialized optional.
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional ( bool cond, argument_type val ) : base(cond,val) {}
sl@0: 
sl@0: #ifndef BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR
sl@0:     // NOTE: MSVC needs templated versions first
sl@0: 
sl@0:     // Creates a deep copy of another convertible optional<U>
sl@0:     // Requires a valid conversion from U to T.
sl@0:     // Can throw if T::T(U const&) does
sl@0:     template<class U>
sl@0:     explicit optional ( optional<U> const& rhs )
sl@0:       :
sl@0:       base()
sl@0:     {
sl@0:       if ( rhs.is_initialized() )
sl@0:         this->construct(rhs.get());
sl@0:     }
sl@0: #endif
sl@0: 
sl@0: #ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
sl@0:     // Creates an optional<T> with an expression which can be either
sl@0:     //  (a) An instance of InPlaceFactory (i.e. in_place(a,b,...,n);
sl@0:     //  (b) An instance of TypedInPlaceFactory ( i.e. in_place<T>(a,b,...,n);
sl@0:     //  (c) Any expression implicitely convertible to the single type
sl@0:     //      of a one-argument T's constructor.
sl@0:     //  (d*) Weak compilers (BCB) might also resolved Expr as optional<T> and optional<U>
sl@0:     //       even though explicit overloads are present for these.
sl@0:     // Depending on the above some T ctor is called.
sl@0:     // Can throw is the resolved T ctor throws.
sl@0:     template<class Expr>
sl@0:     explicit optional ( Expr const& expr ) : base(expr,&expr) {}
sl@0: #endif
sl@0: 
sl@0:     // Creates a deep copy of another optional<T>
sl@0:     // Can throw if T::T(T const&) does
sl@0:     optional ( optional const& rhs ) : base(rhs) {}
sl@0: 
sl@0:    // No-throw (assuming T::~T() doesn't)
sl@0:     ~optional() {}
sl@0: 
sl@0: #if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION)
sl@0:     // Assigns from an expression. See corresponding constructor.
sl@0:     // Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
sl@0:     template<class Expr>
sl@0:     optional& operator= ( Expr expr )
sl@0:       {
sl@0:         this->assign_expr(expr,&expr);
sl@0:         return *this ;
sl@0:       }
sl@0: #endif
sl@0: 
sl@0: 
sl@0: #ifndef BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
sl@0:     // Assigns from another convertible optional<U> (converts && deep-copies the rhs value)
sl@0:     // Requires a valid conversion from U to T.
sl@0:     // Basic Guarantee: If T::T( U const& ) throws, this is left UNINITIALIZED
sl@0:     template<class U>
sl@0:     optional& operator= ( optional<U> const& rhs )
sl@0:       {
sl@0:         this->assign(rhs);
sl@0:         return *this ;
sl@0:       }
sl@0: #endif
sl@0: 
sl@0:     // Assigns from another optional<T> (deep-copies the rhs value)
sl@0:     // Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED
sl@0:     //  (NOTE: On BCB, this operator is not actually called and left is left UNMODIFIED in case of a throw)
sl@0:     optional& operator= ( optional const& rhs )
sl@0:       {
sl@0:         this->assign( rhs ) ;
sl@0:         return *this ;
sl@0:       }
sl@0: 
sl@0:     // Assigns from a T (deep-copies the rhs value)
sl@0:     // Basic Guarantee: If T::( T const& ) throws, this is left UNINITIALIZED
sl@0:     optional& operator= ( argument_type val )
sl@0:       {
sl@0:         this->assign( val ) ;
sl@0:         return *this ;
sl@0:       }
sl@0: 
sl@0:     // Assigns from a "none"
sl@0:     // Which destroys the current value, if any, leaving this UNINITIALIZED
sl@0:     // No-throw (assuming T::~T() doesn't)
sl@0:     optional& operator= ( none_t none_ )
sl@0:       {
sl@0:         this->assign( none_ ) ;
sl@0:         return *this ;
sl@0:       }
sl@0: 
sl@0:     // Returns a reference to the value if this is initialized, otherwise,
sl@0:     // the behaviour is UNDEFINED
sl@0:     // No-throw
sl@0:     reference_const_type get() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
sl@0:     reference_type       get()       { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
sl@0: 
sl@0:     // Returns a copy of the value if this is initialized, 'v' otherwise
sl@0:     reference_const_type get_value_or ( reference_const_type v ) const { return this->is_initialized() ? get() : v ; }
sl@0:     reference_type       get_value_or ( reference_type       v )       { return this->is_initialized() ? get() : v ; }
sl@0:     
sl@0:     // Returns a pointer to the value if this is initialized, otherwise,
sl@0:     // the behaviour is UNDEFINED
sl@0:     // No-throw
sl@0:     pointer_const_type operator->() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; }
sl@0:     pointer_type       operator->()       { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; }
sl@0: 
sl@0:     // Returns a reference to the value if this is initialized, otherwise,
sl@0:     // the behaviour is UNDEFINED
sl@0:     // No-throw
sl@0:     reference_const_type operator *() const { return this->get() ; }
sl@0:     reference_type       operator *()       { return this->get() ; }
sl@0: 
sl@0:     // implicit conversion to "bool"
sl@0:     // No-throw
sl@0:     operator unspecified_bool_type() const { return this->safe_bool() ; }
sl@0: 
sl@0:        // This is provided for those compilers which don't like the conversion to bool
sl@0:        // on some contexts.
sl@0:        bool operator!() const { return !this->is_initialized() ; }
sl@0: } ;
sl@0: 
sl@0: // Returns optional<T>(v)
sl@0: template<class T> 
sl@0: inline 
sl@0: optional<T> make_optional ( T const& v  )
sl@0: {
sl@0:   return optional<T>(v);
sl@0: }
sl@0: 
sl@0: // Returns optional<T>(cond,v)
sl@0: template<class T> 
sl@0: inline 
sl@0: optional<T> make_optional ( bool cond, T const& v )
sl@0: {
sl@0:   return optional<T>(cond,v);
sl@0: }
sl@0: 
sl@0: // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED.
sl@0: // No-throw
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type
sl@0: get ( optional<T> const& opt )
sl@0: {
sl@0:   return opt.get() ;
sl@0: }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::reference_type
sl@0: get ( optional<T>& opt )
sl@0: {
sl@0:   return opt.get() ;
sl@0: }
sl@0: 
sl@0: // Returns a pointer to the value if this is initialized, otherwise, returns NULL.
sl@0: // No-throw
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::pointer_const_type
sl@0: get ( optional<T> const* opt )
sl@0: {
sl@0:   return opt->get_ptr() ;
sl@0: }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::pointer_type
sl@0: get ( optional<T>* opt )
sl@0: {
sl@0:   return opt->get_ptr() ;
sl@0: }
sl@0: 
sl@0: // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED.
sl@0: // No-throw
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type
sl@0: get_optional_value_or ( optional<T> const& opt, BOOST_DEDUCED_TYPENAME optional<T>::reference_const_type v )
sl@0: {
sl@0:   return opt.get_value_or(v) ;
sl@0: }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::reference_type
sl@0: get_optional_value_or ( optional<T>& opt, BOOST_DEDUCED_TYPENAME optional<T>::reference_type v )
sl@0: {
sl@0:   return opt.get_value_or(v) ;
sl@0: }
sl@0: 
sl@0: // Returns a pointer to the value if this is initialized, otherwise, returns NULL.
sl@0: // No-throw
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::pointer_const_type
sl@0: get_pointer ( optional<T> const& opt )
sl@0: {
sl@0:   return opt.get_ptr() ;
sl@0: }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: BOOST_DEDUCED_TYPENAME optional<T>::pointer_type
sl@0: get_pointer ( optional<T>& opt )
sl@0: {
sl@0:   return opt.get_ptr() ;
sl@0: }
sl@0: 
sl@0: // optional's relational operators ( ==, !=, <, >, <=, >= ) have deep-semantics (compare values).
sl@0: // WARNING: This is UNLIKE pointers. Use equal_pointees()/less_pointess() in generic code instead.
sl@0: 
sl@0: 
sl@0: //
sl@0: // optional<T> vs optional<T> cases
sl@0: //
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator == ( optional<T> const& x, optional<T> const& y )
sl@0: { return equal_pointees(x,y); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator < ( optional<T> const& x, optional<T> const& y )
sl@0: { return less_pointees(x,y); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator != ( optional<T> const& x, optional<T> const& y )
sl@0: { return !( x == y ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator > ( optional<T> const& x, optional<T> const& y )
sl@0: { return y < x ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator <= ( optional<T> const& x, optional<T> const& y )
sl@0: { return !( y < x ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator >= ( optional<T> const& x, optional<T> const& y )
sl@0: { return !( x < y ) ; }
sl@0: 
sl@0: 
sl@0: //
sl@0: // optional<T> vs T cases
sl@0: //
sl@0: template<class T>
sl@0: inline
sl@0: bool operator == ( optional<T> const& x, T const& y )
sl@0: { return equal_pointees(x, optional<T>(y)); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator < ( optional<T> const& x, T const& y )
sl@0: { return less_pointees(x, optional<T>(y)); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator != ( optional<T> const& x, T const& y )
sl@0: { return !( x == y ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator > ( optional<T> const& x, T const& y )
sl@0: { return y < x ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator <= ( optional<T> const& x, T const& y )
sl@0: { return !( y < x ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator >= ( optional<T> const& x, T const& y )
sl@0: { return !( x < y ) ; }
sl@0: 
sl@0: //
sl@0: // T vs optional<T> cases
sl@0: //
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator == ( T const& x, optional<T> const& y )
sl@0: { return equal_pointees( optional<T>(x), y ); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator < ( T const& x, optional<T> const& y )
sl@0: { return less_pointees( optional<T>(x), y ); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator != ( T const& x, optional<T> const& y )
sl@0: { return !( x == y ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator > ( T const& x, optional<T> const& y )
sl@0: { return y < x ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator <= ( T const& x, optional<T> const& y )
sl@0: { return !( y < x ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator >= ( T const& x, optional<T> const& y )
sl@0: { return !( x < y ) ; }
sl@0: 
sl@0: 
sl@0: //
sl@0: // optional<T> vs none cases
sl@0: //
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator == ( optional<T> const& x, none_t )
sl@0: { return equal_pointees(x, optional<T>() ); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator < ( optional<T> const& x, none_t )
sl@0: { return less_pointees(x,optional<T>() ); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator != ( optional<T> const& x, none_t y )
sl@0: { return !( x == y ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator > ( optional<T> const& x, none_t y )
sl@0: { return y < x ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator <= ( optional<T> const& x, none_t y )
sl@0: { return !( y < x ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator >= ( optional<T> const& x, none_t y )
sl@0: { return !( x < y ) ; }
sl@0: 
sl@0: //
sl@0: // none vs optional<T> cases
sl@0: //
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator == ( none_t x, optional<T> const& y )
sl@0: { return equal_pointees(optional<T>() ,y); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator < ( none_t x, optional<T> const& y )
sl@0: { return less_pointees(optional<T>() ,y); }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator != ( none_t x, optional<T> const& y )
sl@0: { return !( x == y ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator > ( none_t x, optional<T> const& y )
sl@0: { return y < x ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator <= ( none_t x, optional<T> const& y )
sl@0: { return !( y < x ) ; }
sl@0: 
sl@0: template<class T>
sl@0: inline
sl@0: bool operator >= ( none_t x, optional<T> const& y )
sl@0: { return !( x < y ) ; }
sl@0: 
sl@0: //
sl@0: // The following swap implementation follows the GCC workaround as found in
sl@0: //  "boost/detail/compressed_pair.hpp"
sl@0: //
sl@0: namespace optional_detail {
sl@0: 
sl@0: // GCC < 3.2 gets the using declaration at namespace scope (FLC, DWA)
sl@0: #if BOOST_WORKAROUND(__GNUC__, < 3)                             \
sl@0:     || BOOST_WORKAROUND(__GNUC__, == 3) && __GNUC_MINOR__ <= 2
sl@0:    using std::swap;
sl@0: #define BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
sl@0: #endif
sl@0: 
sl@0: // optional's swap:
sl@0: // If both are initialized, calls swap(T&, T&). If this swap throws, both will remain initialized but their values are now unspecified.
sl@0: // If only one is initialized, calls U.reset(*I), THEN I.reset().
sl@0: // If U.reset(*I) throws, both are left UNCHANGED (U is kept uinitialized and I is never reset)
sl@0: // If both are uninitialized, do nothing (no-throw)
sl@0: template<class T>
sl@0: inline
sl@0: void optional_swap ( optional<T>& x, optional<T>& y )
sl@0: {
sl@0:   if ( !x && !!y )
sl@0:   {
sl@0:     x.reset(*y);
sl@0:     y.reset();
sl@0:   }
sl@0:   else if ( !!x && !y )
sl@0:   {
sl@0:     y.reset(*x);
sl@0:     x.reset();
sl@0:   }
sl@0:   else if ( !!x && !!y )
sl@0:   {
sl@0: // GCC > 3.2 and all other compilers have the using declaration at function scope (FLC)
sl@0: #ifndef BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
sl@0:     // allow for Koenig lookup
sl@0:     using std::swap ;
sl@0: #endif
sl@0:     swap(*x,*y);
sl@0:   }
sl@0: }
sl@0: 
sl@0: } // namespace optional_detail
sl@0: 
sl@0: template<class T> inline void swap ( optional<T>& x, optional<T>& y )
sl@0: {
sl@0:   optional_detail::optional_swap(x,y);
sl@0: }
sl@0: 
sl@0: 
sl@0: } // namespace boost
sl@0: 
sl@0: #endif
sl@0: