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optional.hpp
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optional.hpp
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//
// Copyright (c) 2014-2018 Martin Moene
//
// https://github.com/martinmoene/optional-lite
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#pragma once
#ifndef NONSTD_OPTIONAL_LITE_HPP
#define NONSTD_OPTIONAL_LITE_HPP
#define optional_lite_MAJOR 3
#define optional_lite_MINOR 2
#define optional_lite_PATCH 0
#define optional_lite_VERSION optional_STRINGIFY(optional_lite_MAJOR) "." optional_STRINGIFY(optional_lite_MINOR) "." optional_STRINGIFY(optional_lite_PATCH)
#define optional_STRINGIFY( x ) optional_STRINGIFY_( x )
#define optional_STRINGIFY_( x ) #x
// optional-lite configuration:
#define optional_OPTIONAL_DEFAULT 0
#define optional_OPTIONAL_NONSTD 1
#define optional_OPTIONAL_STD 2
#if !defined( optional_CONFIG_SELECT_OPTIONAL )
# define optional_CONFIG_SELECT_OPTIONAL ( optional_HAVE_STD_OPTIONAL ? optional_OPTIONAL_STD : optional_OPTIONAL_NONSTD )
#endif
// Control presence of exception handling (try and auto discover):
#ifndef optional_CONFIG_NO_EXCEPTIONS
# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
# define optional_CONFIG_NO_EXCEPTIONS 0
# else
# define optional_CONFIG_NO_EXCEPTIONS 1
# endif
#endif
// C++ language version detection (C++20 is speculative):
// Note: VC14.0/1900 (VS2015) lacks too much from C++14.
#ifndef optional_CPLUSPLUS
# if defined(_MSVC_LANG ) && !defined(__clang__)
# define optional_CPLUSPLUS (_MSC_VER == 1900 ? 201103L : _MSVC_LANG )
# else
# define optional_CPLUSPLUS __cplusplus
# endif
#endif
#define optional_CPP98_OR_GREATER ( optional_CPLUSPLUS >= 199711L )
#define optional_CPP11_OR_GREATER ( optional_CPLUSPLUS >= 201103L )
#define optional_CPP11_OR_GREATER_ ( optional_CPLUSPLUS >= 201103L )
#define optional_CPP14_OR_GREATER ( optional_CPLUSPLUS >= 201402L )
#define optional_CPP17_OR_GREATER ( optional_CPLUSPLUS >= 201703L )
#define optional_CPP20_OR_GREATER ( optional_CPLUSPLUS >= 202000L )
// C++ language version (represent 98 as 3):
#define optional_CPLUSPLUS_V ( optional_CPLUSPLUS / 100 - (optional_CPLUSPLUS > 200000 ? 2000 : 1994) )
// Use C++17 std::optional if available and requested:
#if optional_CPP17_OR_GREATER && defined(__has_include )
# if __has_include( <optional> )
# define optional_HAVE_STD_OPTIONAL 1
# else
# define optional_HAVE_STD_OPTIONAL 0
# endif
#else
# define optional_HAVE_STD_OPTIONAL 0
#endif
#define optional_USES_STD_OPTIONAL ( (optional_CONFIG_SELECT_OPTIONAL == optional_OPTIONAL_STD) || ((optional_CONFIG_SELECT_OPTIONAL == optional_OPTIONAL_DEFAULT) && optional_HAVE_STD_OPTIONAL) )
//
// in_place: code duplicated in any-lite, expected-lite, optional-lite, value-ptr-lite, variant-lite:
//
#ifndef nonstd_lite_HAVE_IN_PLACE_TYPES
#define nonstd_lite_HAVE_IN_PLACE_TYPES 1
// C++17 std::in_place in <utility>:
#if optional_CPP17_OR_GREATER
#include <utility>
namespace nonstd {
using std::in_place;
using std::in_place_type;
using std::in_place_index;
using std::in_place_t;
using std::in_place_type_t;
using std::in_place_index_t;
#define nonstd_lite_in_place_t( T) std::in_place_t
#define nonstd_lite_in_place_type_t( T) std::in_place_type_t<T>
#define nonstd_lite_in_place_index_t(K) std::in_place_index_t<K>
#define nonstd_lite_in_place( T) std::in_place_t{}
#define nonstd_lite_in_place_type( T) std::in_place_type_t<T>{}
#define nonstd_lite_in_place_index(K) std::in_place_index_t<K>{}
} // namespace nonstd
#else // optional_CPP17_OR_GREATER
#include <cstddef>
namespace nonstd {
namespace detail {
template< class T >
struct in_place_type_tag {};
template< std::size_t K >
struct in_place_index_tag {};
} // namespace detail
struct in_place_t {};
template< class T >
inline in_place_t in_place( detail::in_place_type_tag<T> /*unused*/ = detail::in_place_type_tag<T>() )
{
return in_place_t();
}
template< std::size_t K >
inline in_place_t in_place( detail::in_place_index_tag<K> /*unused*/ = detail::in_place_index_tag<K>() )
{
return in_place_t();
}
template< class T >
inline in_place_t in_place_type( detail::in_place_type_tag<T> /*unused*/ = detail::in_place_type_tag<T>() )
{
return in_place_t();
}
template< std::size_t K >
inline in_place_t in_place_index( detail::in_place_index_tag<K> /*unused*/ = detail::in_place_index_tag<K>() )
{
return in_place_t();
}
// mimic templated typedef:
#define nonstd_lite_in_place_t( T) nonstd::in_place_t(&)( nonstd::detail::in_place_type_tag<T> )
#define nonstd_lite_in_place_type_t( T) nonstd::in_place_t(&)( nonstd::detail::in_place_type_tag<T> )
#define nonstd_lite_in_place_index_t(K) nonstd::in_place_t(&)( nonstd::detail::in_place_index_tag<K> )
#define nonstd_lite_in_place( T) nonstd::in_place_type<T>
#define nonstd_lite_in_place_type( T) nonstd::in_place_type<T>
#define nonstd_lite_in_place_index(K) nonstd::in_place_index<K>
} // namespace nonstd
#endif // optional_CPP17_OR_GREATER
#endif // nonstd_lite_HAVE_IN_PLACE_TYPES
//
// Using std::optional:
//
#if optional_USES_STD_OPTIONAL
#include <optional>
namespace nonstd {
using std::optional;
using std::bad_optional_access;
using std::hash;
using std::nullopt;
using std::nullopt_t;
using std::operator==;
using std::operator!=;
using std::operator<;
using std::operator<=;
using std::operator>;
using std::operator>=;
using std::make_optional;
using std::swap;
}
#else // optional_USES_STD_OPTIONAL
#include <cassert>
#include <utility>
// optional-lite alignment configuration:
#ifndef optional_CONFIG_MAX_ALIGN_HACK
# define optional_CONFIG_MAX_ALIGN_HACK 0
#endif
#ifndef optional_CONFIG_ALIGN_AS
// no default, used in #if defined()
#endif
#ifndef optional_CONFIG_ALIGN_AS_FALLBACK
# define optional_CONFIG_ALIGN_AS_FALLBACK double
#endif
// Compiler warning suppression:
#if defined(__clang__)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wundef"
#elif defined(__GNUC__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wundef"
#elif defined(_MSC_VER )
# pragma warning( push )
#endif
// half-open range [lo..hi):
#define optional_BETWEEN( v, lo, hi ) ( (lo) <= (v) && (v) < (hi) )
// Compiler versions:
//
// MSVC++ 6.0 _MSC_VER == 1200 (Visual Studio 6.0)
// MSVC++ 7.0 _MSC_VER == 1300 (Visual Studio .NET 2002)
// MSVC++ 7.1 _MSC_VER == 1310 (Visual Studio .NET 2003)
// MSVC++ 8.0 _MSC_VER == 1400 (Visual Studio 2005)
// MSVC++ 9.0 _MSC_VER == 1500 (Visual Studio 2008)
// MSVC++ 10.0 _MSC_VER == 1600 (Visual Studio 2010)
// MSVC++ 11.0 _MSC_VER == 1700 (Visual Studio 2012)
// MSVC++ 12.0 _MSC_VER == 1800 (Visual Studio 2013)
// MSVC++ 14.0 _MSC_VER == 1900 (Visual Studio 2015)
// MSVC++ 14.1 _MSC_VER >= 1910 (Visual Studio 2017)
#if defined(_MSC_VER ) && !defined(__clang__)
# define optional_COMPILER_MSVC_VER (_MSC_VER )
# define optional_COMPILER_MSVC_VERSION (_MSC_VER / 10 - 10 * ( 5 + (_MSC_VER < 1900 ) ) )
#else
# define optional_COMPILER_MSVC_VER 0
# define optional_COMPILER_MSVC_VERSION 0
#endif
#define optional_COMPILER_VERSION( major, minor, patch ) ( 10 * (10 * (major) + (minor) ) + (patch) )
#if defined(__GNUC__) && !defined(__clang__)
# define optional_COMPILER_GNUC_VERSION optional_COMPILER_VERSION(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
#else
# define optional_COMPILER_GNUC_VERSION 0
#endif
#if defined(__clang__)
# define optional_COMPILER_CLANG_VERSION optional_COMPILER_VERSION(__clang_major__, __clang_minor__, __clang_patchlevel__)
#else
# define optional_COMPILER_CLANG_VERSION 0
#endif
#if optional_BETWEEN(optional_COMPILER_MSVC_VERSION, 70, 140 )
# pragma warning( disable: 4345 ) // initialization behavior changed
#endif
#if optional_BETWEEN(optional_COMPILER_MSVC_VERSION, 70, 150 )
# pragma warning( disable: 4814 ) // in C++14 'constexpr' will not imply 'const'
#endif
// Presence of language and library features:
#define optional_HAVE(FEATURE) ( optional_HAVE_##FEATURE )
#ifdef _HAS_CPP0X
# define optional_HAS_CPP0X _HAS_CPP0X
#else
# define optional_HAS_CPP0X 0
#endif
// Unless defined otherwise below, consider VC14 as C++11 for optional-lite:
#if optional_COMPILER_MSVC_VER >= 1900
# undef optional_CPP11_OR_GREATER
# define optional_CPP11_OR_GREATER 1
#endif
#define optional_CPP11_90 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1500)
#define optional_CPP11_100 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1600)
#define optional_CPP11_110 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1700)
#define optional_CPP11_120 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1800)
#define optional_CPP11_140 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1900)
#define optional_CPP11_141 (optional_CPP11_OR_GREATER_ || optional_COMPILER_MSVC_VER >= 1910)
#define optional_CPP14_000 (optional_CPP14_OR_GREATER)
#define optional_CPP17_000 (optional_CPP17_OR_GREATER)
// Presence of C++11 language features:
#define optional_HAVE_CONSTEXPR_11 optional_CPP11_140
#define optional_HAVE_IS_DEFAULT optional_CPP11_140
#define optional_HAVE_NOEXCEPT optional_CPP11_140
#define optional_HAVE_NULLPTR optional_CPP11_100
#define optional_HAVE_REF_QUALIFIER optional_CPP11_140
// Presence of C++14 language features:
#define optional_HAVE_CONSTEXPR_14 optional_CPP14_000
// Presence of C++17 language features:
#define optional_HAVE_NODISCARD optional_CPP17_000
// Presence of C++ library features:
#define optional_HAVE_CONDITIONAL optional_CPP11_120
#define optional_HAVE_REMOVE_CV optional_CPP11_120
#define optional_HAVE_TYPE_TRAITS optional_CPP11_90
#define optional_HAVE_TR1_TYPE_TRAITS (!! optional_COMPILER_GNUC_VERSION )
#define optional_HAVE_TR1_ADD_POINTER (!! optional_COMPILER_GNUC_VERSION )
// C++ feature usage:
#if optional_HAVE( CONSTEXPR_11 )
# define optional_constexpr constexpr
#else
# define optional_constexpr /*constexpr*/
#endif
#if optional_HAVE( IS_DEFAULT )
# define optional_is_default = default;
#else
# define optional_is_default {}
#endif
#if optional_HAVE( CONSTEXPR_14 )
# define optional_constexpr14 constexpr
#else
# define optional_constexpr14 /*constexpr*/
#endif
#if optional_HAVE( NODISCARD )
# define optional_nodiscard [[nodiscard]]
#else
# define optional_nodiscard /*[[nodiscard]]*/
#endif
#if optional_HAVE( NOEXCEPT )
# define optional_noexcept noexcept
#else
# define optional_noexcept /*noexcept*/
#endif
#if optional_HAVE( NULLPTR )
# define optional_nullptr nullptr
#else
# define optional_nullptr NULL
#endif
#if optional_HAVE( REF_QUALIFIER )
// NOLINTNEXTLINE( bugprone-macro-parentheses )
# define optional_ref_qual &
# define optional_refref_qual &&
#else
# define optional_ref_qual /*&*/
# define optional_refref_qual /*&&*/
#endif
// additional includes:
#if optional_CONFIG_NO_EXCEPTIONS
// already included: <cassert>
#else
# include <stdexcept>
#endif
#if optional_CPP11_OR_GREATER
# include <functional>
#endif
#if optional_HAVE( INITIALIZER_LIST )
# include <initializer_list>
#endif
#if optional_HAVE( TYPE_TRAITS )
# include <type_traits>
#elif optional_HAVE( TR1_TYPE_TRAITS )
# include <tr1/type_traits>
#endif
// Method enabling
#if optional_CPP11_OR_GREATER
#define optional_REQUIRES_0(...) \
template< bool B = (__VA_ARGS__), typename std::enable_if<B, int>::type = 0 >
#define optional_REQUIRES_T(...) \
, typename = typename std::enable_if< (__VA_ARGS__), nonstd::optional_lite::detail::enabler >::type
#define optional_REQUIRES_R(R, ...) \
typename std::enable_if< (__VA_ARGS__), R>::type
#define optional_REQUIRES_A(...) \
, typename std::enable_if< (__VA_ARGS__), void*>::type = nullptr
#endif
//
// optional:
//
namespace nonstd { namespace optional_lite {
namespace std11 {
#if optional_CPP11_OR_GREATER
using std::move;
#else
template< typename T > T & move( T & t ) { return t; }
#endif
#if optional_HAVE( CONDITIONAL )
using std::conditional;
#else
template< bool B, typename T, typename F > struct conditional { typedef T type; };
template< typename T, typename F > struct conditional<false, T, F> { typedef F type; };
#endif // optional_HAVE_CONDITIONAL
} // namespace std11
#if optional_CPP11_OR_GREATER
/// type traits C++17:
namespace std17 {
#if optional_CPP17_OR_GREATER
using std::is_swappable;
using std::is_nothrow_swappable;
#elif optional_CPP11_OR_GREATER
namespace detail {
using std::swap;
struct is_swappable
{
template< typename T, typename = decltype( swap( std::declval<T&>(), std::declval<T&>() ) ) >
static std::true_type test( int /*unused*/ );
template< typename >
static std::false_type test(...);
};
struct is_nothrow_swappable
{
// wrap noexcept(expr) in separate function as work-around for VC140 (VS2015):
template< typename T >
static constexpr bool satisfies()
{
return noexcept( swap( std::declval<T&>(), std::declval<T&>() ) );
}
template< typename T >
static auto test( int /*unused*/ ) -> std::integral_constant<bool, satisfies<T>()>{}
template< typename >
static auto test(...) -> std::false_type;
};
} // namespace detail
// is [nothow] swappable:
template< typename T >
struct is_swappable : decltype( detail::is_swappable::test<T>(0) ){};
template< typename T >
struct is_nothrow_swappable : decltype( detail::is_nothrow_swappable::test<T>(0) ){};
#endif // optional_CPP17_OR_GREATER
} // namespace std17
/// type traits C++20:
namespace std20 {
template< typename T >
struct remove_cvref
{
typedef typename std::remove_cv< typename std::remove_reference<T>::type >::type type;
};
} // namespace std20
#endif // optional_CPP11_OR_GREATER
/// class optional
template< typename T >
class optional;
namespace detail {
// for optional_REQUIRES_T
#if optional_CPP11_OR_GREATER
enum class enabler{};
#endif
// C++11 emulation:
struct nulltype{};
template< typename Head, typename Tail >
struct typelist
{
typedef Head head;
typedef Tail tail;
};
#if optional_CONFIG_MAX_ALIGN_HACK
// Max align, use most restricted type for alignment:
#define optional_UNIQUE( name ) optional_UNIQUE2( name, __LINE__ )
#define optional_UNIQUE2( name, line ) optional_UNIQUE3( name, line )
#define optional_UNIQUE3( name, line ) name ## line
#define optional_ALIGN_TYPE( type ) \
type optional_UNIQUE( _t ); struct_t< type > optional_UNIQUE( _st )
template< typename T >
struct struct_t { T _; };
union max_align_t
{
optional_ALIGN_TYPE( char );
optional_ALIGN_TYPE( short int );
optional_ALIGN_TYPE( int );
optional_ALIGN_TYPE( long int );
optional_ALIGN_TYPE( float );
optional_ALIGN_TYPE( double );
optional_ALIGN_TYPE( long double );
optional_ALIGN_TYPE( char * );
optional_ALIGN_TYPE( short int * );
optional_ALIGN_TYPE( int * );
optional_ALIGN_TYPE( long int * );
optional_ALIGN_TYPE( float * );
optional_ALIGN_TYPE( double * );
optional_ALIGN_TYPE( long double * );
optional_ALIGN_TYPE( void * );
#ifdef HAVE_LONG_LONG
optional_ALIGN_TYPE( long long );
#endif
struct Unknown;
Unknown ( * optional_UNIQUE(_) )( Unknown );
Unknown * Unknown::* optional_UNIQUE(_);
Unknown ( Unknown::* optional_UNIQUE(_) )( Unknown );
struct_t< Unknown ( * )( Unknown) > optional_UNIQUE(_);
struct_t< Unknown * Unknown::* > optional_UNIQUE(_);
struct_t< Unknown ( Unknown::* )(Unknown) > optional_UNIQUE(_);
};
#undef optional_UNIQUE
#undef optional_UNIQUE2
#undef optional_UNIQUE3
#undef optional_ALIGN_TYPE
#elif defined( optional_CONFIG_ALIGN_AS ) // optional_CONFIG_MAX_ALIGN_HACK
// Use user-specified type for alignment:
#define optional_ALIGN_AS( unused ) \
optional_CONFIG_ALIGN_AS
#else // optional_CONFIG_MAX_ALIGN_HACK
// Determine POD type to use for alignment:
#define optional_ALIGN_AS( to_align ) \
typename type_of_size< alignment_types, alignment_of< to_align >::value >::type
template< typename T >
struct alignment_of;
template< typename T >
struct alignment_of_hack
{
char c;
T t;
alignment_of_hack();
};
template< size_t A, size_t S >
struct alignment_logic
{
enum { value = A < S ? A : S };
};
template< typename T >
struct alignment_of
{
enum { value = alignment_logic<
sizeof( alignment_of_hack<T> ) - sizeof(T), sizeof(T) >::value };
};
template< typename List, size_t N >
struct type_of_size
{
typedef typename std11::conditional<
N == sizeof( typename List::head ),
typename List::head,
typename type_of_size<typename List::tail, N >::type >::type type;
};
template< size_t N >
struct type_of_size< nulltype, N >
{
typedef optional_CONFIG_ALIGN_AS_FALLBACK type;
};
template< typename T>
struct struct_t { T _; };
#define optional_ALIGN_TYPE( type ) \
typelist< type , typelist< struct_t< type >
struct Unknown;
typedef
optional_ALIGN_TYPE( char ),
optional_ALIGN_TYPE( short ),
optional_ALIGN_TYPE( int ),
optional_ALIGN_TYPE( long ),
optional_ALIGN_TYPE( float ),
optional_ALIGN_TYPE( double ),
optional_ALIGN_TYPE( long double ),
optional_ALIGN_TYPE( char *),
optional_ALIGN_TYPE( short * ),
optional_ALIGN_TYPE( int * ),
optional_ALIGN_TYPE( long * ),
optional_ALIGN_TYPE( float * ),
optional_ALIGN_TYPE( double * ),
optional_ALIGN_TYPE( long double * ),
optional_ALIGN_TYPE( Unknown ( * )( Unknown ) ),
optional_ALIGN_TYPE( Unknown * Unknown::* ),
optional_ALIGN_TYPE( Unknown ( Unknown::* )( Unknown ) ),
nulltype
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > >
alignment_types;
#undef optional_ALIGN_TYPE
#endif // optional_CONFIG_MAX_ALIGN_HACK
/// C++03 constructed union to hold value.
template< typename T >
union storage_t
{
//private:
// template< typename > friend class optional;
typedef T value_type;
storage_t() optional_is_default
explicit storage_t( value_type const & v )
{
construct_value( v );
}
void construct_value( value_type const & v )
{
::new( value_ptr() ) value_type( v );
}
#if optional_CPP11_OR_GREATER
explicit storage_t( value_type && v )
{
construct_value( std::move( v ) );
}
void construct_value( value_type && v )
{
::new( value_ptr() ) value_type( std::move( v ) );
}
template< class... Args >
void emplace( Args&&... args )
{
::new( value_ptr() ) value_type( std::forward<Args>(args)... );
}
template< class U, class... Args >
void emplace( std::initializer_list<U> il, Args&&... args )
{
::new( value_ptr() ) value_type( il, std::forward<Args>(args)... );
}
#endif
void destruct_value()
{
value_ptr()->~T();
}
optional_nodiscard value_type const * value_ptr() const
{
return as<value_type>();
}
value_type * value_ptr()
{
return as<value_type>();
}
optional_nodiscard value_type const & value() const optional_ref_qual
{
return * value_ptr();
}
value_type & value() optional_ref_qual
{
return * value_ptr();
}
#if optional_CPP11_OR_GREATER
optional_nodiscard value_type const && value() const optional_refref_qual
{
return std::move( value() );
}
value_type && value() optional_refref_qual
{
return std::move( value() );
}
#endif
#if optional_CPP11_OR_GREATER
using aligned_storage_t = typename std::aligned_storage< sizeof(value_type), alignof(value_type) >::type;
aligned_storage_t data;
#elif optional_CONFIG_MAX_ALIGN_HACK
typedef struct { unsigned char data[ sizeof(value_type) ]; } aligned_storage_t;
max_align_t hack;
aligned_storage_t data;
#else
typedef optional_ALIGN_AS(value_type) align_as_type;
typedef struct { align_as_type data[ 1 + ( sizeof(value_type) - 1 ) / sizeof(align_as_type) ]; } aligned_storage_t;
aligned_storage_t data;
# undef optional_ALIGN_AS
#endif // optional_CONFIG_MAX_ALIGN_HACK
optional_nodiscard void * ptr() optional_noexcept
{
return &data;
}
optional_nodiscard void const * ptr() const optional_noexcept
{
return &data;
}
template <typename U>
optional_nodiscard U * as()
{
return reinterpret_cast<U*>( ptr() );
}
template <typename U>
optional_nodiscard U const * as() const
{
return reinterpret_cast<U const *>( ptr() );
}
};
} // namespace detail
/// disengaged state tag
struct nullopt_t
{
struct init{};
explicit optional_constexpr nullopt_t( init /*unused*/ ) optional_noexcept {}
};
#if optional_HAVE( CONSTEXPR_11 )
constexpr nullopt_t nullopt{ nullopt_t::init{} };
#else
// extra parenthesis to prevent the most vexing parse:
const nullopt_t nullopt(( nullopt_t::init() ));
#endif
/// optional access error
#if ! optional_CONFIG_NO_EXCEPTIONS
class bad_optional_access : public std::logic_error
{
public:
explicit bad_optional_access()
: logic_error( "bad optional access" ) {}
};
#endif //optional_CONFIG_NO_EXCEPTIONS
/// optional
template< typename T>
class optional
{
private:
template< typename > friend class optional;
typedef void (optional::*safe_bool)() const;
public:
typedef T value_type;
// x.x.3.1, constructors
// 1a - default construct
optional_constexpr optional() optional_noexcept
: has_value_( false )
, contained()
{}
// 1b - construct explicitly empty
// NOLINTNEXTLINE( google-explicit-constructor, hicpp-explicit-conversions )
optional_constexpr optional( nullopt_t /*unused*/ ) optional_noexcept
: has_value_( false )
, contained()
{}
// 2 - copy-construct
optional_constexpr14 optional( optional const & other
#if optional_CPP11_OR_GREATER
optional_REQUIRES_A(
true || std::is_copy_constructible<T>::value
)
#endif
)
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( other.contained.value() );
}
}
#if optional_CPP11_OR_GREATER
// 3 (C++11) - move-construct from optional
optional_constexpr14 optional( optional && other
optional_REQUIRES_A(
true || std::is_move_constructible<T>::value
)
// NOLINTNEXTLINE( performance-noexcept-move-constructor )
) noexcept( std::is_nothrow_move_constructible<T>::value )
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( std::move( other.contained.value() ) );
}
}
// 4a (C++11) - explicit converting copy-construct from optional
template< typename U >
explicit optional( optional<U> const & other
optional_REQUIRES_A(
std::is_constructible<T, U const &>::value
&& !std::is_constructible<T, optional<U> & >::value
&& !std::is_constructible<T, optional<U> && >::value
&& !std::is_constructible<T, optional<U> const & >::value
&& !std::is_constructible<T, optional<U> const && >::value
&& !std::is_convertible< optional<U> & , T>::value
&& !std::is_convertible< optional<U> && , T>::value
&& !std::is_convertible< optional<U> const & , T>::value
&& !std::is_convertible< optional<U> const &&, T>::value
&& !std::is_convertible< U const & , T>::value /*=> explicit */
)
)
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( T{ other.contained.value() } );
}
}
#endif // optional_CPP11_OR_GREATER
// 4b (C++98 and later) - non-explicit converting copy-construct from optional
template< typename U >
// NOLINTNEXTLINE( google-explicit-constructor, hicpp-explicit-conversions )
optional( optional<U> const & other
#if optional_CPP11_OR_GREATER
optional_REQUIRES_A(
std::is_constructible<T, U const &>::value
&& !std::is_constructible<T, optional<U> & >::value
&& !std::is_constructible<T, optional<U> && >::value
&& !std::is_constructible<T, optional<U> const & >::value
&& !std::is_constructible<T, optional<U> const && >::value
&& !std::is_convertible< optional<U> & , T>::value
&& !std::is_convertible< optional<U> && , T>::value
&& !std::is_convertible< optional<U> const & , T>::value
&& !std::is_convertible< optional<U> const &&, T>::value
&& std::is_convertible< U const & , T>::value /*=> non-explicit */
)
#endif // optional_CPP11_OR_GREATER
)
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( other.contained.value() );
}
}
#if optional_CPP11_OR_GREATER
// 5a (C++11) - explicit converting move-construct from optional
template< typename U >
explicit optional( optional<U> && other
optional_REQUIRES_A(
std::is_constructible<T, U &&>::value
&& !std::is_constructible<T, optional<U> & >::value
&& !std::is_constructible<T, optional<U> && >::value
&& !std::is_constructible<T, optional<U> const & >::value
&& !std::is_constructible<T, optional<U> const && >::value
&& !std::is_convertible< optional<U> & , T>::value
&& !std::is_convertible< optional<U> && , T>::value
&& !std::is_convertible< optional<U> const & , T>::value
&& !std::is_convertible< optional<U> const &&, T>::value
&& !std::is_convertible< U &&, T>::value /*=> explicit */
)
)
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( T{ std::move( other.contained.value() ) } );
}
}
// 5a (C++11) - non-explicit converting move-construct from optional
template< typename U >
// NOLINTNEXTLINE( google-explicit-constructor, hicpp-explicit-conversions )
optional( optional<U> && other
optional_REQUIRES_A(
std::is_constructible<T, U &&>::value
&& !std::is_constructible<T, optional<U> & >::value
&& !std::is_constructible<T, optional<U> && >::value
&& !std::is_constructible<T, optional<U> const & >::value
&& !std::is_constructible<T, optional<U> const && >::value
&& !std::is_convertible< optional<U> & , T>::value
&& !std::is_convertible< optional<U> && , T>::value
&& !std::is_convertible< optional<U> const & , T>::value
&& !std::is_convertible< optional<U> const &&, T>::value
&& std::is_convertible< U &&, T>::value /*=> non-explicit */
)
)
: has_value_( other.has_value() )
{
if ( other.has_value() )
{
contained.construct_value( std::move( other.contained.value() ) );
}
}
// 6 (C++11) - in-place construct
template< typename... Args