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mergerfs/src/nonstd/expected.hpp

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// This version targets C++11 and later.
//
// Copyright (C) 2016-2020 Martin Moene.
//
// 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)
//
// expected lite is based on:
// A proposal to add a utility class to represent expected monad
// by Vicente J. Botet Escriba and Pierre Talbot. http:://wg21.link/p0323
#ifndef NONSTD_EXPECTED_LITE_HPP
#define NONSTD_EXPECTED_LITE_HPP
#define expected_lite_MAJOR 0
#define expected_lite_MINOR 6
#define expected_lite_PATCH 2
#define expected_lite_VERSION expected_STRINGIFY(expected_lite_MAJOR) "." expected_STRINGIFY(expected_lite_MINOR) "." expected_STRINGIFY(expected_lite_PATCH)
#define expected_STRINGIFY( x ) expected_STRINGIFY_( x )
#define expected_STRINGIFY_( x ) #x
// expected-lite configuration:
#define nsel_EXPECTED_DEFAULT 0
#define nsel_EXPECTED_NONSTD 1
#define nsel_EXPECTED_STD 2
// tweak header support:
#ifdef __has_include
# if __has_include(<nonstd/expected.tweak.hpp>)
# include <nonstd/expected.tweak.hpp>
# endif
#define expected_HAVE_TWEAK_HEADER 1
#else
#define expected_HAVE_TWEAK_HEADER 0
//# pragma message("expected.hpp: Note: Tweak header not supported.")
#endif
// expected selection and configuration:
#if !defined( nsel_CONFIG_SELECT_EXPECTED )
# define nsel_CONFIG_SELECT_EXPECTED ( nsel_HAVE_STD_EXPECTED ? nsel_EXPECTED_STD : nsel_EXPECTED_NONSTD )
#endif
// Proposal revisions:
//
// DXXXXR0: --
// N4015 : -2 (2014-05-26)
// N4109 : -1 (2014-06-29)
// P0323R0: 0 (2016-05-28)
// P0323R1: 1 (2016-10-12)
// -------:
// P0323R2: 2 (2017-06-15)
// P0323R3: 3 (2017-10-15)
// P0323R4: 4 (2017-11-26)
// P0323R5: 5 (2018-02-08)
// P0323R6: 6 (2018-04-02)
// P0323R7: 7 (2018-06-22) *
//
// expected-lite uses 2 and higher
#ifndef nsel_P0323R
# define nsel_P0323R 7
#endif
// Control presence of C++ exception handling (try and auto discover):
#ifndef nsel_CONFIG_NO_EXCEPTIONS
# if defined(_MSC_VER)
# include <cstddef> // for _HAS_EXCEPTIONS
# endif
# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || (_HAS_EXCEPTIONS)
# define nsel_CONFIG_NO_EXCEPTIONS 0
# else
# define nsel_CONFIG_NO_EXCEPTIONS 1
# endif
#endif
// at default use SEH with MSVC for no C++ exceptions
#ifndef nsel_CONFIG_NO_EXCEPTIONS_SEH
# define nsel_CONFIG_NO_EXCEPTIONS_SEH ( nsel_CONFIG_NO_EXCEPTIONS && _MSC_VER )
#endif
// C++ language version detection (C++23 is speculative):
// Note: VC14.0/1900 (VS2015) lacks too much from C++14.
#ifndef nsel_CPLUSPLUS
# if defined(_MSVC_LANG ) && !defined(__clang__)
# define nsel_CPLUSPLUS (_MSC_VER == 1900 ? 201103L : _MSVC_LANG )
# else
# define nsel_CPLUSPLUS __cplusplus
# endif
#endif
#define nsel_CPP98_OR_GREATER ( nsel_CPLUSPLUS >= 199711L )
#define nsel_CPP11_OR_GREATER ( nsel_CPLUSPLUS >= 201103L )
#define nsel_CPP14_OR_GREATER ( nsel_CPLUSPLUS >= 201402L )
#define nsel_CPP17_OR_GREATER ( nsel_CPLUSPLUS >= 201703L )
#define nsel_CPP20_OR_GREATER ( nsel_CPLUSPLUS >= 202002L )
#define nsel_CPP23_OR_GREATER ( nsel_CPLUSPLUS >= 202300L )
// Use C++23 std::expected if available and requested:
#if nsel_CPP23_OR_GREATER && defined(__has_include )
# if __has_include( <expected> )
# define nsel_HAVE_STD_EXPECTED 1
# else
# define nsel_HAVE_STD_EXPECTED 0
# endif
#else
# define nsel_HAVE_STD_EXPECTED 0
#endif
#define nsel_USES_STD_EXPECTED ( (nsel_CONFIG_SELECT_EXPECTED == nsel_EXPECTED_STD) || ((nsel_CONFIG_SELECT_EXPECTED == nsel_EXPECTED_DEFAULT) && nsel_HAVE_STD_EXPECTED) )
//
// in_place: code duplicated in any-lite, expected-lite, expected-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 nsel_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 // nsel_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> = 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> = 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> = 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> = 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 // nsel_CPP17_OR_GREATER
#endif // nonstd_lite_HAVE_IN_PLACE_TYPES
//
// Using std::expected:
//
#if nsel_USES_STD_EXPECTED
#include <expected>
namespace nonstd {
using std::expected;
// ...
}
#else // nsel_USES_STD_EXPECTED
#include <cassert>
#include <exception>
#include <functional>
#include <initializer_list>
#include <memory>
#include <new>
#include <system_error>
#include <type_traits>
#include <utility>
// additional includes:
#if nsel_CONFIG_NO_EXCEPTIONS
# if nsel_CONFIG_NO_EXCEPTIONS_SEH
# include <windows.h> // for ExceptionCodes
# else
// already included: <cassert>
# endif
#else
# include <stdexcept>
#endif
// C++ feature usage:
#if nsel_CPP11_OR_GREATER
# define nsel_constexpr constexpr
#else
# define nsel_constexpr /*constexpr*/
#endif
#if nsel_CPP14_OR_GREATER
# define nsel_constexpr14 constexpr
#else
# define nsel_constexpr14 /*constexpr*/
#endif
#if nsel_CPP17_OR_GREATER
# define nsel_inline17 inline
#else
# define nsel_inline17 /*inline*/
#endif
// Compiler versions:
//
// MSVC++ 6.0 _MSC_VER == 1200 nsel_COMPILER_MSVC_VERSION == 60 (Visual Studio 6.0)
// MSVC++ 7.0 _MSC_VER == 1300 nsel_COMPILER_MSVC_VERSION == 70 (Visual Studio .NET 2002)
// MSVC++ 7.1 _MSC_VER == 1310 nsel_COMPILER_MSVC_VERSION == 71 (Visual Studio .NET 2003)
// MSVC++ 8.0 _MSC_VER == 1400 nsel_COMPILER_MSVC_VERSION == 80 (Visual Studio 2005)
// MSVC++ 9.0 _MSC_VER == 1500 nsel_COMPILER_MSVC_VERSION == 90 (Visual Studio 2008)
// MSVC++ 10.0 _MSC_VER == 1600 nsel_COMPILER_MSVC_VERSION == 100 (Visual Studio 2010)
// MSVC++ 11.0 _MSC_VER == 1700 nsel_COMPILER_MSVC_VERSION == 110 (Visual Studio 2012)
// MSVC++ 12.0 _MSC_VER == 1800 nsel_COMPILER_MSVC_VERSION == 120 (Visual Studio 2013)
// MSVC++ 14.0 _MSC_VER == 1900 nsel_COMPILER_MSVC_VERSION == 140 (Visual Studio 2015)
// MSVC++ 14.1 _MSC_VER >= 1910 nsel_COMPILER_MSVC_VERSION == 141 (Visual Studio 2017)
// MSVC++ 14.2 _MSC_VER >= 1920 nsel_COMPILER_MSVC_VERSION == 142 (Visual Studio 2019)
#if defined(_MSC_VER) && !defined(__clang__)
# define nsel_COMPILER_MSVC_VER (_MSC_VER )
# define nsel_COMPILER_MSVC_VERSION (_MSC_VER / 10 - 10 * ( 5 + (_MSC_VER < 1900)) )
#else
# define nsel_COMPILER_MSVC_VER 0
# define nsel_COMPILER_MSVC_VERSION 0
#endif
#define nsel_COMPILER_VERSION( major, minor, patch ) ( 10 * ( 10 * (major) + (minor) ) + (patch) )
#if defined(__clang__)
# define nsel_COMPILER_CLANG_VERSION nsel_COMPILER_VERSION(__clang_major__, __clang_minor__, __clang_patchlevel__)
#else
# define nsel_COMPILER_CLANG_VERSION 0
#endif
#if defined(__GNUC__) && !defined(__clang__)
# define nsel_COMPILER_GNUC_VERSION nsel_COMPILER_VERSION(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
#else
# define nsel_COMPILER_GNUC_VERSION 0
#endif
// half-open range [lo..hi):
//#define nsel_BETWEEN( v, lo, hi ) ( (lo) <= (v) && (v) < (hi) )
// Method enabling
#define nsel_REQUIRES_0(...) \
template< bool B = (__VA_ARGS__), typename std::enable_if<B, int>::type = 0 >
#define nsel_REQUIRES_T(...) \
, typename std::enable_if< (__VA_ARGS__), int >::type = 0
#define nsel_REQUIRES_R(R, ...) \
typename std::enable_if< (__VA_ARGS__), R>::type
#define nsel_REQUIRES_A(...) \
, typename std::enable_if< (__VA_ARGS__), void*>::type = nullptr
// Presence of language and library features:
#ifdef _HAS_CPP0X
# define nsel_HAS_CPP0X _HAS_CPP0X
#else
# define nsel_HAS_CPP0X 0
#endif
//#define nsel_CPP11_140 (nsel_CPP11_OR_GREATER || nsel_COMPILER_MSVC_VER >= 1900)
// Clang, GNUC, MSVC warning suppression macros:
#ifdef __clang__
# pragma clang diagnostic push
#elif defined __GNUC__
# pragma GCC diagnostic push
#endif // __clang__
#if nsel_COMPILER_MSVC_VERSION >= 140
# pragma warning( push )
# define nsel_DISABLE_MSVC_WARNINGS(codes) __pragma( warning(disable: codes) )
#else
# define nsel_DISABLE_MSVC_WARNINGS(codes)
#endif
#ifdef __clang__
# define nsel_RESTORE_WARNINGS() _Pragma("clang diagnostic pop")
#elif defined __GNUC__
# define nsel_RESTORE_WARNINGS() _Pragma("GCC diagnostic pop")
#elif nsel_COMPILER_MSVC_VERSION >= 140
# define nsel_RESTORE_WARNINGS() __pragma( warning( pop ) )
#else
# define nsel_RESTORE_WARNINGS()
#endif
// Suppress the following MSVC (GSL) warnings:
// - C26409: Avoid calling new and delete explicitly, use std::make_unique<T> instead (r.11)
nsel_DISABLE_MSVC_WARNINGS( 26409 )
//
// expected:
//
namespace nonstd { namespace expected_lite {
// type traits C++17:
namespace std17 {
#if nsel_CPP17_OR_GREATER
using std::conjunction;
using std::is_swappable;
using std::is_nothrow_swappable;
#else // nsel_CPP17_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 ) -> 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) ){};
// conjunction:
template< typename... > struct conjunction : std::true_type{};
template< typename B1 > struct conjunction<B1> : B1{};
template< typename B1, typename... Bn >
struct conjunction<B1, Bn...> : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type{};
#endif // nsel_CPP17_OR_GREATER
} // namespace std17
// type traits C++20:
namespace std20 {
#if defined(__cpp_lib_remove_cvref)
using std::remove_cvref;
#else
template< typename T >
struct remove_cvref
{
typedef typename std::remove_cv< typename std::remove_reference<T>::type >::type type;
};
#endif
} // namespace std20
// forward declaration:
template< typename T, typename E >
class expected;
namespace detail {
/// discriminated union to hold value or 'error'.
template< typename T, typename E >
class storage_t_impl
{
template< typename, typename > friend class nonstd::expected_lite::expected;
public:
using value_type = T;
using error_type = E;
// no-op construction
storage_t_impl() {}
~storage_t_impl() {}
explicit storage_t_impl( bool has_value )
: m_has_value( has_value )
{}
void construct_value( value_type const & e )
{
new( &m_value ) value_type( e );
}
void construct_value( value_type && e )
{
new( &m_value ) value_type( std::move( e ) );
}
template< class... Args >
void emplace_value( Args&&... args )
{
new( &m_value ) value_type( std::forward<Args>(args)...);
}
template< class U, class... Args >
void emplace_value( std::initializer_list<U> il, Args&&... args )
{
new( &m_value ) value_type( il, std::forward<Args>(args)... );
}
void destruct_value()
{
m_value.~value_type();
}
void construct_error( error_type const & e )
{
new( &m_error ) error_type( e );
}
void construct_error( error_type && e )
{
new( &m_error ) error_type( std::move( e ) );
}
template< class... Args >
void emplace_error( Args&&... args )
{
new( &m_error ) error_type( std::forward<Args>(args)...);
}
template< class U, class... Args >
void emplace_error( std::initializer_list<U> il, Args&&... args )
{
new( &m_error ) error_type( il, std::forward<Args>(args)... );
}
void destruct_error()
{
m_error.~error_type();
}
constexpr value_type const & value() const &
{
return m_value;
}
value_type & value() &
{
return m_value;
}
constexpr value_type const && value() const &&
{
return std::move( m_value );
}
nsel_constexpr14 value_type && value() &&
{
return std::move( m_value );
}
value_type const * value_ptr() const
{
return &m_value;
}
value_type * value_ptr()
{
return &m_value;
}
error_type const & error() const &
{
return m_error;
}
error_type & error() &
{
return m_error;
}
constexpr error_type const && error() const &&
{
return std::move( m_error );
}
nsel_constexpr14 error_type && error() &&
{
return std::move( m_error );
}
bool has_value() const
{
return m_has_value;
}
void set_has_value( bool v )
{
m_has_value = v;
}
private:
union
{
value_type m_value;
error_type m_error;
};
bool m_has_value = false;
};
/// discriminated union to hold only 'error'.
template< typename E >
struct storage_t_impl<void, E>
{
template< typename, typename > friend class nonstd::expected_lite::expected;
public:
using value_type = void;
using error_type = E;
// no-op construction
storage_t_impl() {}
~storage_t_impl() {}
explicit storage_t_impl( bool has_value )
: m_has_value( has_value )
{}
void construct_error( error_type const & e )
{
new( &m_error ) error_type( e );
}
void construct_error( error_type && e )
{
new( &m_error ) error_type( std::move( e ) );
}
template< class... Args >
void emplace_error( Args&&... args )
{
new( &m_error ) error_type( std::forward<Args>(args)...);
}
template< class U, class... Args >
void emplace_error( std::initializer_list<U> il, Args&&... args )
{
new( &m_error ) error_type( il, std::forward<Args>(args)... );
}
void destruct_error()
{
m_error.~error_type();
}
error_type const & error() const &
{
return m_error;
}
error_type & error() &
{
return m_error;
}
constexpr error_type const && error() const &&
{
return std::move( m_error );
}
nsel_constexpr14 error_type && error() &&
{
return std::move( m_error );
}
bool has_value() const
{
return m_has_value;
}
void set_has_value( bool v )
{
m_has_value = v;
}
private:
union
{
char m_dummy;
error_type m_error;
};
bool m_has_value = false;
};
template< typename T, typename E, bool isConstructable, bool isMoveable >
class storage_t
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<T, E>( has_value )
{}
storage_t( storage_t const & other ) = delete;
storage_t( storage_t && other ) = delete;
};
template< typename T, typename E >
class storage_t<T, E, true, true> : public storage_t_impl<T, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<T, E>( has_value )
{}
storage_t( storage_t const & other )
: storage_t_impl<T, E>( other.has_value() )
{
if ( this->has_value() ) this->construct_value( other.value() );
else this->construct_error( other.error() );
}
storage_t(storage_t && other )
: storage_t_impl<T, E>( other.has_value() )
{
if ( this->has_value() ) this->construct_value( std::move( other.value() ) );
else this->construct_error( std::move( other.error() ) );
}
};
template< typename E >
class storage_t<void, E, true, true> : public storage_t_impl<void, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<void, E>( has_value )
{}
storage_t( storage_t const & other )
: storage_t_impl<void, E>( other.has_value() )
{
if ( this->has_value() ) ;
else this->construct_error( other.error() );
}
storage_t(storage_t && other )
: storage_t_impl<void, E>( other.has_value() )
{
if ( this->has_value() ) ;
else this->construct_error( std::move( other.error() ) );
}
};
template< typename T, typename E >
class storage_t<T, E, true, false> : public storage_t_impl<T, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<T, E>( has_value )
{}
storage_t( storage_t const & other )
: storage_t_impl<T, E>(other.has_value())
{
if ( this->has_value() ) this->construct_value( other.value() );
else this->construct_error( other.error() );
}
storage_t( storage_t && other ) = delete;
};
template< typename E >
class storage_t<void, E, true, false> : public storage_t_impl<void, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<void, E>( has_value )
{}
storage_t( storage_t const & other )
: storage_t_impl<void, E>(other.has_value())
{
if ( this->has_value() ) ;
else this->construct_error( other.error() );
}
storage_t( storage_t && other ) = delete;
};
template< typename T, typename E >
class storage_t<T, E, false, true> : public storage_t_impl<T, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<T, E>( has_value )
{}
storage_t( storage_t const & other ) = delete;
storage_t( storage_t && other )
: storage_t_impl<T, E>( other.has_value() )
{
if ( this->has_value() ) this->construct_value( std::move( other.value() ) );
else this->construct_error( std::move( other.error() ) );
}
};
template< typename E >
class storage_t<void, E, false, true> : public storage_t_impl<void, E>
{
public:
storage_t() = default;
~storage_t() = default;
explicit storage_t( bool has_value )
: storage_t_impl<void, E>( has_value )
{}
storage_t( storage_t const & other ) = delete;
storage_t( storage_t && other )
: storage_t_impl<void, E>( other.has_value() )
{
if ( this->has_value() ) ;
else this->construct_error( std::move( other.error() ) );
}
};
} // namespace detail
/// x.x.5 Unexpected object type; unexpected_type; C++17 and later can also use aliased type unexpected.
#if nsel_P0323R <= 2
template< typename E = std::exception_ptr >
class unexpected_type
#else
template< typename E >
class unexpected_type
#endif // nsel_P0323R
{
public:
using error_type = E;
// x.x.5.2.1 Constructors
// unexpected_type() = delete;
constexpr unexpected_type( unexpected_type const & ) = default;
constexpr unexpected_type( unexpected_type && ) = default;
template< typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, Args&&...>::value
)
>
constexpr explicit unexpected_type( nonstd_lite_in_place_t(E), Args &&... args )
: m_error( std::forward<Args>( args )...)
{}
template< typename U, typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, std::initializer_list<U>, Args&&...>::value
)
>
constexpr explicit unexpected_type( nonstd_lite_in_place_t(E), std::initializer_list<U> il, Args &&... args )
: m_error( il, std::forward<Args>( args )...)
{}
template< typename E2
nsel_REQUIRES_T(
std::is_constructible<E,E2>::value
&& !std::is_same< typename std20::remove_cvref<E2>::type, nonstd_lite_in_place_t(E2) >::value
&& !std::is_same< typename std20::remove_cvref<E2>::type, unexpected_type >::value
)
>
constexpr explicit unexpected_type( E2 && error )
: m_error( std::forward<E2>( error ) )
{}
template< typename E2
nsel_REQUIRES_T(
std::is_constructible< E, E2>::value
&& !std::is_constructible<E, unexpected_type<E2> & >::value
&& !std::is_constructible<E, unexpected_type<E2> >::value
&& !std::is_constructible<E, unexpected_type<E2> const & >::value
&& !std::is_constructible<E, unexpected_type<E2> const >::value
&& !std::is_convertible< unexpected_type<E2> &, E>::value
&& !std::is_convertible< unexpected_type<E2> , E>::value
&& !std::is_convertible< unexpected_type<E2> const &, E>::value
&& !std::is_convertible< unexpected_type<E2> const , E>::value
&& !std::is_convertible< E2 const &, E>::value /*=> explicit */
)
>
constexpr explicit unexpected_type( unexpected_type<E2> const & error )
: m_error( E{ error.value() } )
{}
template< typename E2
nsel_REQUIRES_T(
std::is_constructible< E, E2>::value
&& !std::is_constructible<E, unexpected_type<E2> & >::value
&& !std::is_constructible<E, unexpected_type<E2> >::value
&& !std::is_constructible<E, unexpected_type<E2> const & >::value
&& !std::is_constructible<E, unexpected_type<E2> const >::value
&& !std::is_convertible< unexpected_type<E2> &, E>::value
&& !std::is_convertible< unexpected_type<E2> , E>::value
&& !std::is_convertible< unexpected_type<E2> const &, E>::value
&& !std::is_convertible< unexpected_type<E2> const , E>::value
&& std::is_convertible< E2 const &, E>::value /*=> explicit */
)
>
constexpr /*non-explicit*/ unexpected_type( unexpected_type<E2> const & error )
: m_error( error.value() )
{}
template< typename E2
nsel_REQUIRES_T(
std::is_constructible< E, E2>::value
&& !std::is_constructible<E, unexpected_type<E2> & >::value
&& !std::is_constructible<E, unexpected_type<E2> >::value
&& !std::is_constructible<E, unexpected_type<E2> const & >::value
&& !std::is_constructible<E, unexpected_type<E2> const >::value
&& !std::is_convertible< unexpected_type<E2> &, E>::value
&& !std::is_convertible< unexpected_type<E2> , E>::value
&& !std::is_convertible< unexpected_type<E2> const &, E>::value
&& !std::is_convertible< unexpected_type<E2> const , E>::value
&& !std::is_convertible< E2 const &, E>::value /*=> explicit */
)
>
constexpr explicit unexpected_type( unexpected_type<E2> && error )
: m_error( E{ std::move( error.value() ) } )
{}
template< typename E2
nsel_REQUIRES_T(
std::is_constructible< E, E2>::value
&& !std::is_constructible<E, unexpected_type<E2> & >::value
&& !std::is_constructible<E, unexpected_type<E2> >::value
&& !std::is_constructible<E, unexpected_type<E2> const & >::value
&& !std::is_constructible<E, unexpected_type<E2> const >::value
&& !std::is_convertible< unexpected_type<E2> &, E>::value
&& !std::is_convertible< unexpected_type<E2> , E>::value
&& !std::is_convertible< unexpected_type<E2> const &, E>::value
&& !std::is_convertible< unexpected_type<E2> const , E>::value
&& std::is_convertible< E2 const &, E>::value /*=> non-explicit */
)
>
constexpr /*non-explicit*/ unexpected_type( unexpected_type<E2> && error )
: m_error( std::move( error.value() ) )
{}
// x.x.5.2.2 Assignment
nsel_constexpr14 unexpected_type& operator=( unexpected_type const & ) = default;
nsel_constexpr14 unexpected_type& operator=( unexpected_type && ) = default;
template< typename E2 = E >
nsel_constexpr14 unexpected_type & operator=( unexpected_type<E2> const & other )
{
unexpected_type{ other.value() }.swap( *this );
return *this;
}
template< typename E2 = E >
nsel_constexpr14 unexpected_type & operator=( unexpected_type<E2> && other )
{
unexpected_type{ std::move( other.value() ) }.swap( *this );
return *this;
}
// x.x.5.2.3 Observers
nsel_constexpr14 E & value() & noexcept
{
return m_error;
}
constexpr E const & value() const & noexcept
{
return m_error;
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
nsel_constexpr14 E && value() && noexcept
{
return std::move( m_error );
}
constexpr E const && value() const && noexcept
{
return std::move( m_error );
}
#endif
// x.x.5.2.4 Swap
template< typename U=E >
nsel_REQUIRES_R( void,
std17::is_swappable<U>::value
)
swap( unexpected_type & other ) noexcept (
std17::is_nothrow_swappable<U>::value
)
{
using std::swap;
swap( m_error, other.m_error );
}
// TODO: ??? unexpected_type: in-class friend operator==, !=
private:
error_type m_error;
};
#if nsel_CPP17_OR_GREATER
/// template deduction guide:
template< typename E >
unexpected_type( E ) -> unexpected_type< E >;
#endif
/// class unexpected_type, std::exception_ptr specialization (P0323R2)
#if !nsel_CONFIG_NO_EXCEPTIONS
#if nsel_P0323R <= 2
// TODO: Should expected be specialized for particular E types such as exception_ptr and how?
// See p0323r7 2.1. Ergonomics, http://wg21.link/p0323
template<>
class unexpected_type< std::exception_ptr >
{
public:
using error_type = std::exception_ptr;
unexpected_type() = delete;
~unexpected_type(){}
explicit unexpected_type( std::exception_ptr const & error )
: m_error( error )
{}
explicit unexpected_type(std::exception_ptr && error )
: m_error( std::move( error ) )
{}
template< typename E >
explicit unexpected_type( E error )
: m_error( std::make_exception_ptr( error ) )
{}
std::exception_ptr const & value() const
{
return m_error;
}
std::exception_ptr & value()
{
return m_error;
}
private:
std::exception_ptr m_error;
};
#endif // nsel_P0323R
#endif // !nsel_CONFIG_NO_EXCEPTIONS
/// x.x.4, Unexpected equality operators
template< typename E1, typename E2 >
constexpr bool operator==( unexpected_type<E1> const & x, unexpected_type<E2> const & y )
{
return x.value() == y.value();
}
template< typename E1, typename E2 >
constexpr bool operator!=( unexpected_type<E1> const & x, unexpected_type<E2> const & y )
{
return ! ( x == y );
}
#if nsel_P0323R <= 2
template< typename E >
constexpr bool operator<( unexpected_type<E> const & x, unexpected_type<E> const & y )
{
return x.value() < y.value();
}
template< typename E >
constexpr bool operator>( unexpected_type<E> const & x, unexpected_type<E> const & y )
{
return ( y < x );
}
template< typename E >
constexpr bool operator<=( unexpected_type<E> const & x, unexpected_type<E> const & y )
{
return ! ( y < x );
}
template< typename E >
constexpr bool operator>=( unexpected_type<E> const & x, unexpected_type<E> const & y )
{
return ! ( x < y );
}
#endif // nsel_P0323R
/// x.x.5 Specialized algorithms
template< typename E
nsel_REQUIRES_T(
std17::is_swappable<E>::value
)
>
void swap( unexpected_type<E> & x, unexpected_type<E> & y) noexcept ( noexcept ( x.swap(y) ) )
{
x.swap( y );
}
#if nsel_P0323R <= 2
// unexpected: relational operators for std::exception_ptr:
inline constexpr bool operator<( unexpected_type<std::exception_ptr> const & /*x*/, unexpected_type<std::exception_ptr> const & /*y*/ )
{
return false;
}
inline constexpr bool operator>( unexpected_type<std::exception_ptr> const & /*x*/, unexpected_type<std::exception_ptr> const & /*y*/ )
{
return false;
}
inline constexpr bool operator<=( unexpected_type<std::exception_ptr> const & x, unexpected_type<std::exception_ptr> const & y )
{
return ( x == y );
}
inline constexpr bool operator>=( unexpected_type<std::exception_ptr> const & x, unexpected_type<std::exception_ptr> const & y )
{
return ( x == y );
}
#endif // nsel_P0323R
// unexpected: traits
#if nsel_P0323R <= 3
template< typename E>
struct is_unexpected : std::false_type {};
template< typename E>
struct is_unexpected< unexpected_type<E> > : std::true_type {};
#endif // nsel_P0323R
// unexpected: factory
// keep make_unexpected() removed in p0323r2 for pre-C++17:
template< typename E>
nsel_constexpr14 auto
make_unexpected( E && value ) -> unexpected_type< typename std::decay<E>::type >
{
return unexpected_type< typename std::decay<E>::type >( std::forward<E>(value) );
}
#if nsel_P0323R <= 3
/*nsel_constexpr14*/ auto inline
make_unexpected_from_current_exception() -> unexpected_type< std::exception_ptr >
{
return unexpected_type< std::exception_ptr >( std::current_exception() );
}
#endif // nsel_P0323R
/// x.x.6, x.x.7 expected access error
template< typename E >
class bad_expected_access;
/// x.x.7 bad_expected_access<void>: expected access error
template <>
class bad_expected_access< void > : public std::exception
{
public:
explicit bad_expected_access()
: std::exception()
{}
};
/// x.x.6 bad_expected_access: expected access error
#if !nsel_CONFIG_NO_EXCEPTIONS
template< typename E >
class bad_expected_access : public bad_expected_access< void >
{
public:
using error_type = E;
explicit bad_expected_access( error_type error )
: m_error( error )
{}
virtual char const * what() const noexcept override
{
return "bad_expected_access";
}
nsel_constexpr14 error_type & error() &
{
return m_error;
}
constexpr error_type const & error() const &
{
return m_error;
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
nsel_constexpr14 error_type && error() &&
{
return std::move( m_error );
}
constexpr error_type const && error() const &&
{
return std::move( m_error );
}
#endif
private:
error_type m_error;
};
#endif // nsel_CONFIG_NO_EXCEPTIONS
/// x.x.8 unexpect tag, in_place_unexpected tag: construct an error
struct unexpect_t{};
using in_place_unexpected_t = unexpect_t;
nsel_inline17 constexpr unexpect_t unexpect{};
nsel_inline17 constexpr unexpect_t in_place_unexpected{};
/// class error_traits
#if nsel_CONFIG_NO_EXCEPTIONS
namespace detail {
inline bool text( char const * /*text*/ ) { return true; }
}
template< typename Error >
struct error_traits
{
static void rethrow( Error const & /*e*/ )
{
#if nsel_CONFIG_NO_EXCEPTIONS_SEH
RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
#else
assert( false && detail::text("throw bad_expected_access<Error>{ e };") );
#endif
}
};
template<>
struct error_traits< std::exception_ptr >
{
static void rethrow( std::exception_ptr const & /*e*/ )
{
#if nsel_CONFIG_NO_EXCEPTIONS_SEH
RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
#else
assert( false && detail::text("throw bad_expected_access<std::exception_ptr>{ e };") );
#endif
}
};
template<>
struct error_traits< std::error_code >
{
static void rethrow( std::error_code const & /*e*/ )
{
#if nsel_CONFIG_NO_EXCEPTIONS_SEH
RaiseException( EXCEPTION_ACCESS_VIOLATION, EXCEPTION_NONCONTINUABLE, 0, NULL );
#else
assert( false && detail::text("throw std::system_error( e );") );
#endif
}
};
#else // nsel_CONFIG_NO_EXCEPTIONS
template< typename Error >
struct error_traits
{
static void rethrow( Error const & e )
{
throw bad_expected_access<Error>{ e };
}
};
template<>
struct error_traits< std::exception_ptr >
{
static void rethrow( std::exception_ptr const & e )
{
std::rethrow_exception( e );
}
};
template<>
struct error_traits< std::error_code >
{
static void rethrow( std::error_code const & e )
{
throw std::system_error( e );
}
};
#endif // nsel_CONFIG_NO_EXCEPTIONS
} // namespace expected_lite
// provide nonstd::unexpected_type:
using expected_lite::unexpected_type;
namespace expected_lite {
/// class expected
#if nsel_P0323R <= 2
template< typename T, typename E = std::exception_ptr >
class expected
#else
template< typename T, typename E >
class expected
#endif // nsel_P0323R
{
private:
template< typename, typename > friend class expected;
public:
using value_type = T;
using error_type = E;
using unexpected_type = nonstd::unexpected_type<E>;
template< typename U >
struct rebind
{
using type = expected<U, error_type>;
};
// x.x.4.1 constructors
nsel_REQUIRES_0(
std::is_default_constructible<T>::value
)
nsel_constexpr14 expected()
: contained( true )
{
contained.construct_value( value_type() );
}
nsel_constexpr14 expected( expected const & ) = default;
nsel_constexpr14 expected( expected && ) = default;
template< typename U, typename G
nsel_REQUIRES_T(
std::is_constructible< T, U const &>::value
&& std::is_constructible<E, G const &>::value
&& !std::is_constructible<T, expected<U, G> & >::value
&& !std::is_constructible<T, expected<U, G> && >::value
&& !std::is_constructible<T, expected<U, G> const & >::value
&& !std::is_constructible<T, expected<U, G> const && >::value
&& !std::is_convertible< expected<U, G> & , T>::value
&& !std::is_convertible< expected<U, G> &&, T>::value
&& !std::is_convertible< expected<U, G> const & , T>::value
&& !std::is_convertible< expected<U, G> const &&, T>::value
&& (!std::is_convertible<U const &, T>::value || !std::is_convertible<G const &, E>::value ) /*=> explicit */
)
>
nsel_constexpr14 explicit expected( expected<U, G> const & other )
: contained( other.has_value() )
{
if ( has_value() ) contained.construct_value( T{ other.contained.value() } );
else contained.construct_error( E{ other.contained.error() } );
}
template< typename U, typename G
nsel_REQUIRES_T(
std::is_constructible< T, U const &>::value
&& std::is_constructible<E, G const &>::value
&& !std::is_constructible<T, expected<U, G> & >::value
&& !std::is_constructible<T, expected<U, G> && >::value
&& !std::is_constructible<T, expected<U, G> const & >::value
&& !std::is_constructible<T, expected<U, G> const && >::value
&& !std::is_convertible< expected<U, G> & , T>::value
&& !std::is_convertible< expected<U, G> &&, T>::value
&& !std::is_convertible< expected<U, G> const &, T>::value
&& !std::is_convertible< expected<U, G> const &&, T>::value
&& !(!std::is_convertible<U const &, T>::value || !std::is_convertible<G const &, E>::value ) /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( expected<U, G> const & other )
: contained( other.has_value() )
{
if ( has_value() ) contained.construct_value( other.contained.value() );
else contained.construct_error( other.contained.error() );
}
template< typename U, typename G
nsel_REQUIRES_T(
std::is_constructible< T, U>::value
&& std::is_constructible<E, G>::value
&& !std::is_constructible<T, expected<U, G> & >::value
&& !std::is_constructible<T, expected<U, G> && >::value
&& !std::is_constructible<T, expected<U, G> const & >::value
&& !std::is_constructible<T, expected<U, G> const && >::value
&& !std::is_convertible< expected<U, G> & , T>::value
&& !std::is_convertible< expected<U, G> &&, T>::value
&& !std::is_convertible< expected<U, G> const & , T>::value
&& !std::is_convertible< expected<U, G> const &&, T>::value
&& (!std::is_convertible<U, T>::value || !std::is_convertible<G, E>::value ) /*=> explicit */
)
>
nsel_constexpr14 explicit expected( expected<U, G> && other )
: contained( other.has_value() )
{
if ( has_value() ) contained.construct_value( T{ std::move( other.contained.value() ) } );
else contained.construct_error( E{ std::move( other.contained.error() ) } );
}
template< typename U, typename G
nsel_REQUIRES_T(
std::is_constructible< T, U>::value
&& std::is_constructible<E, G>::value
&& !std::is_constructible<T, expected<U, G> & >::value
&& !std::is_constructible<T, expected<U, G> && >::value
&& !std::is_constructible<T, expected<U, G> const & >::value
&& !std::is_constructible<T, expected<U, G> const && >::value
&& !std::is_convertible< expected<U, G> & , T>::value
&& !std::is_convertible< expected<U, G> &&, T>::value
&& !std::is_convertible< expected<U, G> const & , T>::value
&& !std::is_convertible< expected<U, G> const &&, T>::value
&& !(!std::is_convertible<U, T>::value || !std::is_convertible<G, E>::value ) /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( expected<U, G> && other )
: contained( other.has_value() )
{
if ( has_value() ) contained.construct_value( std::move( other.contained.value() ) );
else contained.construct_error( std::move( other.contained.error() ) );
}
template< typename U = T
nsel_REQUIRES_T(
std::is_copy_constructible<U>::value
)
>
nsel_constexpr14 expected( value_type const & value )
: contained( true )
{
contained.construct_value( value );
}
template< typename U = T
nsel_REQUIRES_T(
std::is_constructible<T,U&&>::value
&& !std::is_same<typename std20::remove_cvref<U>::type, nonstd_lite_in_place_t(U)>::value
&& !std::is_same< expected<T,E> , typename std20::remove_cvref<U>::type>::value
&& !std::is_same<nonstd::unexpected_type<E>, typename std20::remove_cvref<U>::type>::value
&& !std::is_convertible<U&&,T>::value /*=> explicit */
)
>
nsel_constexpr14 explicit expected( U && value ) noexcept
(
std::is_nothrow_move_constructible<U>::value &&
std::is_nothrow_move_constructible<E>::value
)
: contained( true )
{
contained.construct_value( T{ std::forward<U>( value ) } );
}
template< typename U = T
nsel_REQUIRES_T(
std::is_constructible<T,U&&>::value
&& !std::is_same<typename std20::remove_cvref<U>::type, nonstd_lite_in_place_t(U)>::value
&& !std::is_same< expected<T,E> , typename std20::remove_cvref<U>::type>::value
&& !std::is_same<nonstd::unexpected_type<E>, typename std20::remove_cvref<U>::type>::value
&& std::is_convertible<U&&,T>::value /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( U && value ) noexcept
(
std::is_nothrow_move_constructible<U>::value &&
std::is_nothrow_move_constructible<E>::value
)
: contained( true )
{
contained.construct_value( std::forward<U>( value ) );
}
// construct error:
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G const & >::value
&& !std::is_convertible< G const &, E>::value /*=> explicit */
)
>
nsel_constexpr14 explicit expected( nonstd::unexpected_type<G> const & error )
: contained( false )
{
contained.construct_error( E{ error.value() } );
}
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G const & >::value
&& std::is_convertible< G const &, E>::value /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( nonstd::unexpected_type<G> const & error )
: contained( false )
{
contained.construct_error( error.value() );
}
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G&& >::value
&& !std::is_convertible< G&&, E>::value /*=> explicit */
)
>
nsel_constexpr14 explicit expected( nonstd::unexpected_type<G> && error )
: contained( false )
{
contained.construct_error( E{ std::move( error.value() ) } );
}
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G&& >::value
&& std::is_convertible< G&&, E>::value /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( nonstd::unexpected_type<G> && error )
: contained( false )
{
contained.construct_error( std::move( error.value() ) );
}
// in-place construction, value
template< typename... Args
nsel_REQUIRES_T(
std::is_constructible<T, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( nonstd_lite_in_place_t(T), Args&&... args )
: contained( true )
{
contained.emplace_value( std::forward<Args>( args )... );
}
template< typename U, typename... Args
nsel_REQUIRES_T(
std::is_constructible<T, std::initializer_list<U>, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( nonstd_lite_in_place_t(T), std::initializer_list<U> il, Args&&... args )
: contained( true )
{
contained.emplace_value( il, std::forward<Args>( args )... );
}
// in-place construction, error
template< typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( unexpect_t, Args&&... args )
: contained( false )
{
contained.emplace_error( std::forward<Args>( args )... );
}
template< typename U, typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, std::initializer_list<U>, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( unexpect_t, std::initializer_list<U> il, Args&&... args )
: contained( false )
{
contained.emplace_error( il, std::forward<Args>( args )... );
}
// x.x.4.2 destructor
// TODO: ~expected: triviality
// Effects: If T is not cv void and is_trivially_destructible_v<T> is false and bool(*this), calls val.~T(). If is_trivially_destructible_v<E> is false and !bool(*this), calls unexpect.~unexpected<E>().
// Remarks: If either T is cv void or is_trivially_destructible_v<T> is true, and is_trivially_destructible_v<E> is true, then this destructor shall be a trivial destructor.
~expected()
{
if ( has_value() ) contained.destruct_value();
else contained.destruct_error();
}
// x.x.4.3 assignment
expected & operator=( expected const & other )
{
expected( other ).swap( *this );
return *this;
}
expected & operator=( expected && other ) noexcept
(
std::is_nothrow_move_constructible< T>::value
&& std::is_nothrow_move_assignable< T>::value
&& std::is_nothrow_move_constructible<E>::value // added for missing
&& std::is_nothrow_move_assignable< E>::value ) // nothrow above
{
expected( std::move( other ) ).swap( *this );
return *this;
}
template< typename U
nsel_REQUIRES_T(
!std::is_same<expected<T,E>, typename std20::remove_cvref<U>::type>::value
&& std17::conjunction<std::is_scalar<T>, std::is_same<T, std::decay<U>> >::value
&& std::is_constructible<T ,U>::value
&& std::is_assignable< T&,U>::value
&& std::is_nothrow_move_constructible<E>::value )
>
expected & operator=( U && value )
{
expected( std::forward<U>( value ) ).swap( *this );
return *this;
}
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G const&>::value &&
std::is_copy_constructible<G>::value // TODO: std::is_nothrow_copy_constructible<G>
&& std::is_copy_assignable<G>::value
)
>
expected & operator=( nonstd::unexpected_type<G> const & error )
{
expected( unexpect, error.value() ).swap( *this );
return *this;
}
template< typename G = E
nsel_REQUIRES_T(
std::is_constructible<E, G&&>::value &&
std::is_move_constructible<G>::value // TODO: std::is_nothrow_move_constructible<G>
&& std::is_move_assignable<G>::value
)
>
expected & operator=( nonstd::unexpected_type<G> && error )
{
expected( unexpect, std::move( error.value() ) ).swap( *this );
return *this;
}
template< typename... Args
nsel_REQUIRES_T(
std::is_nothrow_constructible<T, Args&&...>::value
)
>
value_type & emplace( Args &&... args )
{
expected( nonstd_lite_in_place(T), std::forward<Args>(args)... ).swap( *this );
return value();
}
template< typename U, typename... Args
nsel_REQUIRES_T(
std::is_nothrow_constructible<T, std::initializer_list<U>&, Args&&...>::value
)
>
value_type & emplace( std::initializer_list<U> il, Args &&... args )
{
expected( nonstd_lite_in_place(T), il, std::forward<Args>(args)... ).swap( *this );
return value();
}
// x.x.4.4 swap
template< typename U=T, typename G=E >
nsel_REQUIRES_R( void,
std17::is_swappable< U>::value
&& std17::is_swappable<G>::value
&& ( std::is_move_constructible<U>::value || std::is_move_constructible<G>::value )
)
swap( expected & other ) noexcept
(
std::is_nothrow_move_constructible<T>::value && std17::is_nothrow_swappable<T&>::value &&
std::is_nothrow_move_constructible<E>::value && std17::is_nothrow_swappable<E&>::value
)
{
using std::swap;
if ( bool(*this) && bool(other) ) { swap( contained.value(), other.contained.value() ); }
else if ( ! bool(*this) && ! bool(other) ) { swap( contained.error(), other.contained.error() ); }
else if ( bool(*this) && ! bool(other) ) { error_type t( std::move( other.error() ) );
other.contained.destruct_error();
other.contained.construct_value( std::move( contained.value() ) );
contained.destruct_value();
contained.construct_error( std::move( t ) );
bool has_value = contained.has_value();
bool other_has_value = other.has_value();
other.contained.set_has_value(has_value);
contained.set_has_value(other_has_value);
}
else if ( ! bool(*this) && bool(other) ) { other.swap( *this ); }
}
// x.x.4.5 observers
constexpr value_type const * operator ->() const
{
return assert( has_value() ), contained.value_ptr();
}
value_type * operator ->()
{
return assert( has_value() ), contained.value_ptr();
}
constexpr value_type const & operator *() const &
{
return assert( has_value() ), contained.value();
}
value_type & operator *() &
{
return assert( has_value() ), contained.value();
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
constexpr value_type const && operator *() const &&
{
return std::move( ( assert( has_value() ), contained.value() ) );
}
nsel_constexpr14 value_type && operator *() &&
{
return std::move( ( assert( has_value() ), contained.value() ) );
}
#endif
constexpr explicit operator bool() const noexcept
{
return has_value();
}
constexpr bool has_value() const noexcept
{
return contained.has_value();
}
constexpr value_type const & value() const &
{
return has_value()
? ( contained.value() )
: ( error_traits<error_type>::rethrow( contained.error() ), contained.value() );
}
value_type & value() &
{
return has_value()
? ( contained.value() )
: ( error_traits<error_type>::rethrow( contained.error() ), contained.value() );
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
constexpr value_type const && value() const &&
{
return std::move( has_value()
? ( contained.value() )
: ( error_traits<error_type>::rethrow( contained.error() ), contained.value() ) );
}
nsel_constexpr14 value_type && value() &&
{
return std::move( has_value()
? ( contained.value() )
: ( error_traits<error_type>::rethrow( contained.error() ), contained.value() ) );
}
#endif
constexpr error_type const & error() const &
{
return assert( ! has_value() ), contained.error();
}
error_type & error() &
{
return assert( ! has_value() ), contained.error();
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
constexpr error_type const && error() const &&
{
return std::move( ( assert( ! has_value() ), contained.error() ) );
}
error_type && error() &&
{
return std::move( ( assert( ! has_value() ), contained.error() ) );
}
#endif
constexpr unexpected_type get_unexpected() const
{
return make_unexpected( contained.error() );
}
template< typename Ex >
bool has_exception() const
{
using ContainedEx = typename std::remove_reference< decltype( get_unexpected().value() ) >::type;
return ! has_value() && std::is_base_of< Ex, ContainedEx>::value;
}
template< typename U
nsel_REQUIRES_T(
std::is_copy_constructible< T>::value
&& std::is_convertible<U&&, T>::value
)
>
value_type value_or( U && v ) const &
{
return has_value()
? contained.value()
: static_cast<T>( std::forward<U>( v ) );
}
template< typename U
nsel_REQUIRES_T(
std::is_move_constructible< T>::value
&& std::is_convertible<U&&, T>::value
)
>
value_type value_or( U && v ) &&
{
return has_value()
? std::move( contained.value() )
: static_cast<T>( std::forward<U>( v ) );
}
// unwrap()
// template <class U, class E>
// constexpr expected<U,E> expected<expected<U,E>,E>::unwrap() const&;
// template <class T, class E>
// constexpr expected<T,E> expected<T,E>::unwrap() const&;
// template <class U, class E>
// expected<U,E> expected<expected<U,E>, E>::unwrap() &&;
// template <class T, class E>
// template expected<T,E> expected<T,E>::unwrap() &&;
// factories
// template< typename Ex, typename F>
// expected<T,E> catch_exception(F&& f);
// template< typename F>
// expected<decltype(func(declval<T>())),E> map(F&& func) ;
// template< typename F>
// 'see below' bind(F&& func);
// template< typename F>
// expected<T,E> catch_error(F&& f);
// template< typename F>
// 'see below' then(F&& func);
private:
detail::storage_t
<
T
,E
, std::is_copy_constructible<T>::value && std::is_copy_constructible<E>::value
, std::is_move_constructible<T>::value && std::is_move_constructible<E>::value
>
contained;
};
/// class expected, void specialization
template< typename E >
class expected<void, E>
{
private:
template< typename, typename > friend class expected;
public:
using value_type = void;
using error_type = E;
using unexpected_type = nonstd::unexpected_type<E>;
// x.x.4.1 constructors
constexpr expected() noexcept
: contained( true )
{}
nsel_constexpr14 expected( expected const & other ) = default;
nsel_constexpr14 expected( expected && other ) = default;
constexpr explicit expected( nonstd_lite_in_place_t(void) )
: contained( true )
{}
template< typename G = E
nsel_REQUIRES_T(
!std::is_convertible<G const &, E>::value /*=> explicit */
)
>
nsel_constexpr14 explicit expected( nonstd::unexpected_type<G> const & error )
: contained( false )
{
contained.construct_error( E{ error.value() } );
}
template< typename G = E
nsel_REQUIRES_T(
std::is_convertible<G const &, E>::value /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( nonstd::unexpected_type<G> const & error )
: contained( false )
{
contained.construct_error( error.value() );
}
template< typename G = E
nsel_REQUIRES_T(
!std::is_convertible<G&&, E>::value /*=> explicit */
)
>
nsel_constexpr14 explicit expected( nonstd::unexpected_type<G> && error )
: contained( false )
{
contained.construct_error( E{ std::move( error.value() ) } );
}
template< typename G = E
nsel_REQUIRES_T(
std::is_convertible<G&&, E>::value /*=> non-explicit */
)
>
nsel_constexpr14 /*non-explicit*/ expected( nonstd::unexpected_type<G> && error )
: contained( false )
{
contained.construct_error( std::move( error.value() ) );
}
template< typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( unexpect_t, Args&&... args )
: contained( false )
{
contained.emplace_error( std::forward<Args>( args )... );
}
template< typename U, typename... Args
nsel_REQUIRES_T(
std::is_constructible<E, std::initializer_list<U>, Args&&...>::value
)
>
nsel_constexpr14 explicit expected( unexpect_t, std::initializer_list<U> il, Args&&... args )
: contained( false )
{
contained.emplace_error( il, std::forward<Args>( args )... );
}
// destructor
~expected()
{
if ( ! has_value() )
{
contained.destruct_error();
}
}
// x.x.4.3 assignment
expected & operator=( expected const & other )
{
expected( other ).swap( *this );
return *this;
}
expected & operator=( expected && other ) noexcept
(
std::is_nothrow_move_assignable<E>::value &&
std::is_nothrow_move_constructible<E>::value )
{
expected( std::move( other ) ).swap( *this );
return *this;
}
void emplace()
{
expected().swap( *this );
}
// x.x.4.4 swap
template< typename G = E >
nsel_REQUIRES_R( void,
std17::is_swappable<G>::value
&& std::is_move_constructible<G>::value
)
swap( expected & other ) noexcept
(
std::is_nothrow_move_constructible<E>::value && std17::is_nothrow_swappable<E&>::value
)
{
using std::swap;
if ( ! bool(*this) && ! bool(other) ) { swap( contained.error(), other.contained.error() ); }
else if ( bool(*this) && ! bool(other) ) { contained.construct_error( std::move( other.error() ) );
bool has_value = contained.has_value();
bool other_has_value = other.has_value();
other.contained.set_has_value(has_value);
contained.set_has_value(other_has_value);
}
else if ( ! bool(*this) && bool(other) ) { other.swap( *this ); }
}
// x.x.4.5 observers
constexpr explicit operator bool() const noexcept
{
return has_value();
}
constexpr bool has_value() const noexcept
{
return contained.has_value();
}
void value() const
{
if ( ! has_value() )
{
error_traits<error_type>::rethrow( contained.error() );
}
}
constexpr error_type const & error() const &
{
return assert( ! has_value() ), contained.error();
}
error_type & error() &
{
return assert( ! has_value() ), contained.error();
}
#if !nsel_COMPILER_GNUC_VERSION || nsel_COMPILER_GNUC_VERSION >= 490
constexpr error_type const && error() const &&
{
return std::move( ( assert( ! has_value() ), contained.error() ) );
}
error_type && error() &&
{
return std::move( ( assert( ! has_value() ), contained.error() ) );
}
#endif
constexpr unexpected_type get_unexpected() const
{
return make_unexpected( contained.error() );
}
template< typename Ex >
bool has_exception() const
{
using ContainedEx = typename std::remove_reference< decltype( get_unexpected().value() ) >::type;
return ! has_value() && std::is_base_of< Ex, ContainedEx>::value;
}
// template constexpr 'see below' unwrap() const&;
//
// template 'see below' unwrap() &&;
// factories
// template< typename Ex, typename F>
// expected<void,E> catch_exception(F&& f);
//
// template< typename F>
// expected<decltype(func()), E> map(F&& func) ;
//
// template< typename F>
// 'see below' bind(F&& func) ;
//
// template< typename F>
// expected<void,E> catch_error(F&& f);
//
// template< typename F>
// 'see below' then(F&& func);
private:
detail::storage_t
<
void
, E
, std::is_copy_constructible<E>::value
, std::is_move_constructible<E>::value
>
contained;
};
// x.x.4.6 expected<>: comparison operators
template< typename T1, typename E1, typename T2, typename E2
nsel_REQUIRES_T(
!std::is_void<T1>::value && !std::is_void<T2>::value
)
>
constexpr bool operator==( expected<T1,E1> const & x, expected<T2,E2> const & y )
{
return bool(x) != bool(y) ? false : bool(x) ? *x == *y : x.error() == y.error();
}
template< typename T1, typename E1, typename T2, typename E2
nsel_REQUIRES_T(
std::is_void<T1>::value && std::is_void<T2>::value
)
>
constexpr bool operator==( expected<T1,E1> const & x, expected<T2,E2> const & y )
{
return bool(x) != bool(y) ? false : bool(x) || static_cast<bool>( x.error() == y.error() );
}
template< typename T1, typename E1, typename T2, typename E2 >
constexpr bool operator!=( expected<T1,E1> const & x, expected<T2,E2> const & y )
{
return !(x == y);
}
#if nsel_P0323R <= 2
template< typename T, typename E >
constexpr bool operator<( expected<T,E> const & x, expected<T,E> const & y )
{
return (!y) ? false : (!x) ? true : *x < *y;
}
template< typename T, typename E >
constexpr bool operator>( expected<T,E> const & x, expected<T,E> const & y )
{
return (y < x);
}
template< typename T, typename E >
constexpr bool operator<=( expected<T,E> const & x, expected<T,E> const & y )
{
return !(y < x);
}
template< typename T, typename E >
constexpr bool operator>=( expected<T,E> const & x, expected<T,E> const & y )
{
return !(x < y);
}
#endif
// x.x.4.7 expected: comparison with T
template< typename T1, typename E1, typename T2
nsel_REQUIRES_T(
!std::is_void<T1>::value
)
>
constexpr bool operator==( expected<T1,E1> const & x, T2 const & v )
{
return bool(x) ? *x == v : false;
}
template< typename T1, typename E1, typename T2
nsel_REQUIRES_T(
!std::is_void<T1>::value
)
>
constexpr bool operator==(T2 const & v, expected<T1,E1> const & x )
{
return bool(x) ? v == *x : false;
}
template< typename T1, typename E1, typename T2 >
constexpr bool operator!=( expected<T1,E1> const & x, T2 const & v )
{
return bool(x) ? *x != v : true;
}
template< typename T1, typename E1, typename T2 >
constexpr bool operator!=( T2 const & v, expected<T1,E1> const & x )
{
return bool(x) ? v != *x : true;
}
#if nsel_P0323R <= 2
template< typename T, typename E >
constexpr bool operator<( expected<T,E> const & x, T const & v )
{
return bool(x) ? *x < v : true;
}
template< typename T, typename E >
constexpr bool operator<( T const & v, expected<T,E> const & x )
{
return bool(x) ? v < *x : false;
}
template< typename T, typename E >
constexpr bool operator>( T const & v, expected<T,E> const & x )
{
return bool(x) ? *x < v : false;
}
template< typename T, typename E >
constexpr bool operator>( expected<T,E> const & x, T const & v )
{
return bool(x) ? v < *x : false;
}
template< typename T, typename E >
constexpr bool operator<=( T const & v, expected<T,E> const & x )
{
return bool(x) ? ! ( *x < v ) : false;
}
template< typename T, typename E >
constexpr bool operator<=( expected<T,E> const & x, T const & v )
{
return bool(x) ? ! ( v < *x ) : true;
}
template< typename T, typename E >
constexpr bool operator>=( expected<T,E> const & x, T const & v )
{
return bool(x) ? ! ( *x < v ) : false;
}
template< typename T, typename E >
constexpr bool operator>=( T const & v, expected<T,E> const & x )
{
return bool(x) ? ! ( v < *x ) : true;
}
#endif // nsel_P0323R
// x.x.4.8 expected: comparison with unexpected_type
template< typename T1, typename E1 , typename E2 >
constexpr bool operator==( expected<T1,E1> const & x, unexpected_type<E2> const & u )
{
return (!x) ? x.get_unexpected() == u : false;
}
template< typename T1, typename E1 , typename E2 >
constexpr bool operator==( unexpected_type<E2> const & u, expected<T1,E1> const & x )
{
return ( x == u );
}
template< typename T1, typename E1 , typename E2 >
constexpr bool operator!=( expected<T1,E1> const & x, unexpected_type<E2> const & u )
{
return ! ( x == u );
}
template< typename T1, typename E1 , typename E2 >
constexpr bool operator!=( unexpected_type<E2> const & u, expected<T1,E1> const & x )
{
return ! ( x == u );
}
#if nsel_P0323R <= 2
template< typename T, typename E >
constexpr bool operator<( expected<T,E> const & x, unexpected_type<E> const & u )
{
return (!x) ? ( x.get_unexpected() < u ) : false;
}
template< typename T, typename E >
constexpr bool operator<( unexpected_type<E> const & u, expected<T,E> const & x )
{
return (!x) ? ( u < x.get_unexpected() ) : true ;
}
template< typename T, typename E >
constexpr bool operator>( expected<T,E> const & x, unexpected_type<E> const & u )
{
return ( u < x );
}
template< typename T, typename E >
constexpr bool operator>( unexpected_type<E> const & u, expected<T,E> const & x )
{
return ( x < u );
}
template< typename T, typename E >
constexpr bool operator<=( expected<T,E> const & x, unexpected_type<E> const & u )
{
return ! ( u < x );
}
template< typename T, typename E >
constexpr bool operator<=( unexpected_type<E> const & u, expected<T,E> const & x)
{
return ! ( x < u );
}
template< typename T, typename E >
constexpr bool operator>=( expected<T,E> const & x, unexpected_type<E> const & u )
{
return ! ( u > x );
}
template< typename T, typename E >
constexpr bool operator>=( unexpected_type<E> const & u, expected<T,E> const & x )
{
return ! ( x > u );
}
#endif // nsel_P0323R
/// x.x.x Specialized algorithms
template< typename T, typename E
nsel_REQUIRES_T(
( std::is_void<T>::value || std::is_move_constructible<T>::value )
&& std::is_move_constructible<E>::value
&& std17::is_swappable<T>::value
&& std17::is_swappable<E>::value )
>
void swap( expected<T,E> & x, expected<T,E> & y ) noexcept ( noexcept ( x.swap(y) ) )
{
x.swap( y );
}
#if nsel_P0323R <= 3
template< typename T >
constexpr auto make_expected( T && v ) -> expected< typename std::decay<T>::type >
{
return expected< typename std::decay<T>::type >( std::forward<T>( v ) );
}
// expected<void> specialization:
auto inline make_expected() -> expected<void>
{
return expected<void>( in_place );
}
template< typename T >
constexpr auto make_expected_from_current_exception() -> expected<T>
{
return expected<T>( make_unexpected_from_current_exception() );
}
template< typename T >
auto make_expected_from_exception( std::exception_ptr v ) -> expected<T>
{
return expected<T>( unexpected_type<std::exception_ptr>( std::forward<std::exception_ptr>( v ) ) );
}
template< typename T, typename E >
constexpr auto make_expected_from_error( E e ) -> expected<T, typename std::decay<E>::type>
{
return expected<T, typename std::decay<E>::type>( make_unexpected( e ) );
}
template< typename F
nsel_REQUIRES_T( ! std::is_same<typename std::result_of<F()>::type, void>::value )
>
/*nsel_constexpr14*/
auto make_expected_from_call( F f ) -> expected< typename std::result_of<F()>::type >
{
try
{
return make_expected( f() );
}
catch (...)
{
return make_unexpected_from_current_exception();
}
}
template< typename F
nsel_REQUIRES_T( std::is_same<typename std::result_of<F()>::type, void>::value )
>
/*nsel_constexpr14*/
auto make_expected_from_call( F f ) -> expected<void>
{
try
{
f();
return make_expected();
}
catch (...)
{
return make_unexpected_from_current_exception();
}
}
#endif // nsel_P0323R
} // namespace expected_lite
using namespace expected_lite;
// using expected_lite::expected;
// using ...
} // namespace nonstd
namespace std {
// expected: hash support
template< typename T, typename E >
struct hash< nonstd::expected<T,E> >
{
using result_type = std::size_t;
using argument_type = nonstd::expected<T,E>;
constexpr result_type operator()(argument_type const & arg) const
{
return arg ? std::hash<T>{}(*arg) : result_type{};
}
};
// TBD - ?? remove? see spec.
template< typename T, typename E >
struct hash< nonstd::expected<T&,E> >
{
using result_type = std::size_t;
using argument_type = nonstd::expected<T&,E>;
constexpr result_type operator()(argument_type const & arg) const
{
return arg ? std::hash<T>{}(*arg) : result_type{};
}
};
// TBD - implement
// bool(e), hash<expected<void,E>>()(e) shall evaluate to the hashing true;
// otherwise it evaluates to an unspecified value if E is exception_ptr or
// a combination of hashing false and hash<E>()(e.error()).
template< typename E >
struct hash< nonstd::expected<void,E> >
{
};
} // namespace std
namespace nonstd {
// void unexpected() is deprecated && removed in C++17
#if nsel_CPP17_OR_GREATER || nsel_COMPILER_MSVC_VERSION > 141
template< typename E >
using unexpected = unexpected_type<E>;
#endif
} // namespace nonstd
#undef nsel_REQUIRES
#undef nsel_REQUIRES_0
#undef nsel_REQUIRES_T
nsel_RESTORE_WARNINGS()
#endif // nsel_USES_STD_EXPECTED
#endif // NONSTD_EXPECTED_LITE_HPP