// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal. | |
// | |
// 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 | |
// | |
#ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP | |
#define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP | |
#include <new> | |
#include <algorithm> | |
#include <boost/config.hpp> | |
#include <boost/assert.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_reference.hpp> | |
#include <boost/type_traits/is_reference.hpp> | |
#include <boost/mpl/if.hpp> | |
#include <boost/mpl/bool.hpp> | |
#include <boost/mpl/not.hpp> | |
#include <boost/detail/reference_content.hpp> | |
#include <boost/none.hpp> | |
#include <boost/utility/swap.hpp> | |
#include <boost/utility/addressof.hpp> | |
#include <boost/utility/compare_pointees.hpp> | |
#include <boost/utility/in_place_factory.hpp> | |
#include <boost/optional/optional_fwd.hpp> | |
#if BOOST_WORKAROUND(BOOST_MSVC, == 1200) | |
// VC6.0 has the following bug: | |
// When a templated assignment operator exist, an implicit conversion | |
// constructing an optional<T> is used when assigment of the form: | |
// optional<T> opt ; opt = T(...); | |
// is compiled. | |
// However, optional's ctor is _explicit_ and the assignemt shouldn't compile. | |
// Therefore, for VC6.0 templated assignment is disabled. | |
// | |
#define BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT | |
#endif | |
#if BOOST_WORKAROUND(BOOST_MSVC, == 1300) | |
// VC7.0 has the following bug: | |
// When both a non-template and a template copy-ctor exist | |
// and the templated version is made 'explicit', the explicit is also | |
// given to the non-templated version, making the class non-implicitely-copyable. | |
// | |
#define BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR | |
#endif | |
#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION,<=700) | |
// AFAICT only VC7.1 correctly resolves the overload set | |
// that includes the in-place factory taking functions, | |
// so for the other VC 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__) && (__GNUC__ * 100 + __GNUC_MINOR__) > 302 \ | |
&& !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 ; | |
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 ; | |
typedef raw_type* pointer_const_type ; | |
typedef raw_type* pointer_type ; | |
typedef raw_type& argument_type ; | |
} ; | |
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 bool (this_type::*unspecified_bool_type)() const; | |
typedef BOOST_DEDUCED_TYPENAME types::reference_type reference_type ; | |
typedef BOOST_DEDUCED_TYPENAME types::reference_const_type reference_const_type ; | |
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); | |
} | |
// 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()); | |
} | |
// 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); | |
} | |
// 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()); | |
} | |
} | |
// 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() ) | |
assign_value(static_cast<value_type>(rhs.get()), is_reference_predicate() ); | |
else destroy(); | |
} | |
else | |
{ | |
if ( rhs.is_initialized() ) | |
construct(static_cast<value_type>(rhs.get())); | |
} | |
} | |
// 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); | |
} | |
// Assigns from "none", destroying the current value, if any, leaving this UNINITIALIZED | |
// No-throw (assuming T::~T() doesn't) | |
void assign ( none_t ) { destroy(); } | |
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT | |
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 | |
public : | |
// Destroys the current value, if any, leaving this UNINITIALIZED | |
// No-throw (assuming T::~T() doesn't) | |
void reset() { destroy(); } | |
// 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_NO_INPLACE_FACTORY_SUPPORT | |
// 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 | |
// Constructs using any expression implicitely 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 implicitely 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()); | |
} | |
#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 | |
// | |
// 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 | |
void assign_value ( argument_type val, is_not_reference_tag ) { get_impl() = val; } | |
void assign_value ( argument_type val, is_reference_tag ) { construct(val); } | |
void destroy() | |
{ | |
if ( m_initialized ) | |
destroy_impl(is_reference_predicate()) ; | |
} | |
unspecified_bool_type safe_bool() const { return m_initialized ? &this_type::is_initialized : 0 ; } | |
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::~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 ; | |
typedef BOOST_DEDUCED_TYPENAME base::unspecified_bool_type unspecified_bool_type ; | |
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::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() : base() {} | |
// Creates an optional<T> uninitialized. | |
// No-throw | |
optional( none_t none_ ) : base(none_) {} | |
// Creates an optional<T> initialized with 'val'. | |
// Can throw if T::T(T const&) does | |
optional ( argument_type val ) : base(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) {} | |
#ifndef BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR | |
// 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()); | |
} | |
#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 implicitely 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 is the resolved T ctor throws. | |
template<class Expr> | |
explicit optional ( Expr const& expr ) : base(expr,boost::addressof(expr)) {} | |
#endif | |
// 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) ) {} | |
// 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 | |
template<class Expr> | |
optional& operator= ( Expr const& expr ) | |
{ | |
this->assign_expr(expr,boost::addressof(expr)); | |
return *this ; | |
} | |
#endif | |
#ifndef BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT | |
// 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 ; | |
} | |
#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 ; | |
} | |
// 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 "none" | |
// Which destroys the current value, if any, leaving this UNINITIALIZED | |
// No-throw (assuming T::~T() doesn't) | |
optional& operator= ( none_t none_ ) | |
{ | |
this->assign( none_ ) ; | |
return *this ; | |
} | |
void swap( optional & arg ) | |
{ | |
// allow for Koenig lookup | |
using boost::swap; | |
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 *() const { return this->get() ; } | |
reference_type operator *() { return this->get() ; } | |
// implicit conversion to "bool" | |
// No-throw | |
operator unspecified_bool_type() const { return this->safe_bool() ; } | |
// This is provided for those compilers which don't like the conversion to bool | |
// on some contexts. | |
bool operator!() const { return !this->is_initialized() ; } | |
} ; | |
// 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() ; | |
} | |
// 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 ) | |
{ return equal_pointees(x, optional<T>() ); } | |
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 y ) | |
{ return !( x == y ) ; } | |
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 x, optional<T> const& y ) | |
{ return equal_pointees(optional<T>() ,y); } | |
template<class T> | |
inline | |
bool operator < ( none_t x, optional<T> const& y ) | |
{ return less_pointees(optional<T>() ,y); } | |
template<class T> | |
inline | |
bool operator != ( none_t x, optional<T> const& y ) | |
{ return !( x == 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 = boost::in_place(); | |
else if ( !hasY ) | |
y = boost::in_place(); | |
// 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 ; | |
} | |
}; | |
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()); | |
} | |
} | |
}; | |
} // namespace optional_detail | |
template<class T> | |
struct optional_swap_should_use_default_constructor : has_nothrow_default_constructor<T> {} ; | |
template<class T> inline void swap ( optional<T>& x, optional<T>& y ) | |
{ | |
optional_detail::swap_selector<optional_swap_should_use_default_constructor<T>::value>::optional_swap(x, y); | |
} | |
} // namespace boost | |
#endif |