build: switch to C++14
Replace our homegrown implementation of optional (based
on Boost.Optional) with optional-lite by Martin Moene.
Change-Id: I4632cbc7c705a94af0b85a335515e3430bf3cb1f
Refs: #3076
diff --git a/src/util/nonstd/optional.hpp b/src/util/nonstd/optional.hpp
new file mode 100644
index 0000000..8a4a31a
--- /dev/null
+++ b/src/util/nonstd/optional.hpp
@@ -0,0 +1,1205 @@
+//
+// Copyright (c) 2014-2017 Martin Moene
+//
+// https://github.com/martinmoene/optional-lite
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#pragma once
+
+#ifndef NONSTD_OPTIONAL_LITE_HPP
+#define NONSTD_OPTIONAL_LITE_HPP
+
+#define optional_lite_VERSION "2.3.2"
+
+// Compiler detection (C++20 is speculative):
+// Note: MSVC supports C++14 since it supports C++17.
+
+#ifdef _MSVC_LANG
+# define optional_MSVC_LANG _MSVC_LANG
+#else
+# define optional_MSVC_LANG 0
+#endif
+
+#define optional_CPP11 (__cplusplus == 201103L )
+#define optional_CPP11_OR_GREATER (__cplusplus >= 201103L || optional_MSVC_LANG >= 201103L )
+#define optional_CPP14_OR_GREATER (__cplusplus >= 201402L || optional_MSVC_LANG >= 201703L )
+#define optional_CPP17_OR_GREATER (__cplusplus >= 201703L || optional_MSVC_LANG >= 201703L )
+#define optional_CPP20_OR_GREATER (__cplusplus >= 202000L || optional_MSVC_LANG >= 202000L )
+
+// use C++17 std::optional if available:
+
+#if defined( __has_include )
+# define optional_HAS_INCLUDE( arg ) __has_include( arg )
+#else
+# define optional_HAS_INCLUDE( arg ) 0
+#endif
+
+#define optional_HAVE_STD_OPTIONAL ( optional_CPP17_OR_GREATER && optional_HAS_INCLUDE( <optional> ) )
+
+#if optional_HAVE_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::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;
+
+ 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 // C++17 std::optional
+
+#include <cassert>
+#include <stdexcept>
+#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:
+
+#ifdef __clang__
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Wundef"
+#elif defined __GNUC__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wundef"
+#endif
+
+// half-open range [lo..hi):
+#define optional_BETWEEN( v, lo, hi ) ( lo <= v && v < hi )
+
+#if defined(_MSC_VER) && !defined(__clang__)
+# define optional_COMPILER_MSVC_VERSION (_MSC_VER / 10 - 10 * ( 5 + (_MSC_VER < 1900)) )
+#else
+# define optional_COMPILER_MSVC_VERSION 0
+#endif
+
+#define optional_COMPILER_VERSION( major, minor, patch ) ( 10 * (10 * major + minor ) + patch )
+
+#if defined __GNUC__
+# 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( push )
+# pragma warning( disable: 4345 ) // initialization behavior changed
+#endif
+
+#if optional_BETWEEN(optional_COMPILER_MSVC_VERSION, 70, 150 )
+# pragma warning( push )
+# 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 )
+
+// Presence of C++11 language features:
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 100
+# define optional_HAVE_AUTO 1
+# define optional_HAVE_NULLPTR 1
+# define optional_HAVE_STATIC_ASSERT 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 120
+# define optional_HAVE_DEFAULT_FUNCTION_TEMPLATE_ARG 1
+# define optional_HAVE_INITIALIZER_LIST 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 140
+# define optional_HAVE_ALIAS_TEMPLATE 1
+# define optional_HAVE_CONSTEXPR_11 1
+# define optional_HAVE_ENUM_CLASS 1
+# define optional_HAVE_EXPLICIT_CONVERSION 1
+# define optional_HAVE_IS_DEFAULT 1
+# define optional_HAVE_IS_DELETE 1
+# define optional_HAVE_NOEXCEPT 1
+# define optional_HAVE_REF_QUALIFIER 1
+#endif
+
+// Presence of C++14 language features:
+
+#if optional_CPP14_OR_GREATER
+# define optional_HAVE_CONSTEXPR_14 1
+#endif
+
+// Presence of C++17 language features:
+
+#if optional_CPP17_OR_GREATER
+# define optional_HAVE_ENUM_CLASS_CONSTRUCTION_FROM_UNDERLYING_TYPE 1
+#endif
+
+// Presence of C++ library features:
+
+#if optional_COMPILER_GNUC_VERSION
+# define optional_HAVE_TR1_TYPE_TRAITS 1
+# define optional_HAVE_TR1_ADD_POINTER 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 90
+# define optional_HAVE_TYPE_TRAITS 1
+# define optional_HAVE_STD_ADD_POINTER 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 110
+# define optional_HAVE_ARRAY 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 120
+# define optional_HAVE_CONDITIONAL 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 140 || (optional_COMPILER_MSVC_VERSION >= 90 && _HAS_CPP0X)
+# define optional_HAVE_CONTAINER_DATA_METHOD 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 120
+# define optional_HAVE_REMOVE_CV 1
+#endif
+
+#if optional_CPP11_OR_GREATER || optional_COMPILER_MSVC_VERSION >= 140
+# define optional_HAVE_SIZED_TYPES 1
+#endif
+
+// For the rest, consider VC14 as C++11 for optional-lite:
+
+#if optional_COMPILER_MSVC_VERSION >= 140
+# undef optional_CPP11_OR_GREATER
+# define optional_CPP11_OR_GREATER 1
+#endif
+
+// C++ feature usage:
+
+#if optional_HAVE( CONSTEXPR_11 )
+# define optional_constexpr constexpr
+#else
+# define optional_constexpr /*constexpr*/
+#endif
+
+#if optional_HAVE( CONSTEXPR_14 )
+# define optional_constexpr14 constexpr
+#else
+# define optional_constexpr14 /*constexpr*/
+#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 )
+# define optional_ref_qual &
+# define optional_refref_qual &&
+#else
+# define optional_ref_qual /*&*/
+# define optional_refref_qual /*&&*/
+#endif
+
+// additional includes:
+
+#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
+
+// type traits needed:
+
+namespace nonstd { namespace optional_lite { namespace detail {
+
+#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
+
+}}}
+
+//
+// in_place: code duplicated in any-lite, optional-lite, variant-lite:
+//
+
+#ifndef nonstd_lite_HAVE_IN_PLACE_TYPES
+
+namespace nonstd {
+
+namespace detail {
+
+template< class T >
+struct in_place_type_tag {};
+
+template< std::size_t I >
+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 I >
+inline in_place_t in_place( detail::in_place_index_tag<I> = detail::in_place_index_tag<I>() )
+{
+ 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 I >
+inline in_place_t in_place_index( detail::in_place_index_tag<I> = detail::in_place_index_tag<I>() )
+{
+ return in_place_t();
+}
+
+// mimic templated typedef:
+
+#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(T) nonstd::in_place_t(&)( nonstd::detail::in_place_index_tag<I> )
+
+#define nonstd_lite_HAVE_IN_PLACE_TYPES 1
+
+} // namespace nonstd
+
+#endif // nonstd_lite_HAVE_IN_PLACE_TYPES
+
+//
+// optional:
+//
+
+namespace nonstd { namespace optional_lite {
+
+/// class optional
+
+template< typename T >
+class optional;
+
+namespace detail {
+
+// 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 <unsigned A, unsigned 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 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:
+ friend class optional<T>;
+
+ typedef T value_type;
+
+ storage_t() {}
+
+ 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
+
+ storage_t( value_type && v )
+ {
+ construct_value( std::move( v ) );
+ }
+
+ void construct_value( value_type && v )
+ {
+ ::new( value_ptr() ) value_type( std::move( v ) );
+ }
+
+#endif
+
+ void destruct_value()
+ {
+ value_ptr()->~T();
+ }
+
+ value_type const * value_ptr() const
+ {
+ return as<value_type>();
+ }
+
+ value_type * value_ptr()
+ {
+ return as<value_type>();
+ }
+
+ 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
+
+ value_type const && value() const optional_refref_qual
+ {
+ return * value_ptr();
+ }
+
+ value_type && value() optional_refref_qual
+ {
+ return * value_ptr();
+ }
+
+#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
+
+ void * ptr() optional_noexcept
+ {
+ return &data;
+ }
+
+ void const * ptr() const optional_noexcept
+ {
+ return &data;
+ }
+
+ template <typename U>
+ U * as()
+ {
+ return reinterpret_cast<U*>( ptr() );
+ }
+
+ template <typename U>
+ U const * as() const
+ {
+ return reinterpret_cast<U const *>( ptr() );
+ }
+};
+
+} // namespace detail
+
+/// disengaged state tag
+
+struct nullopt_t
+{
+ struct init{};
+ optional_constexpr nullopt_t( init ) {}
+};
+
+#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
+
+class bad_optional_access : public std::logic_error
+{
+public:
+ explicit bad_optional_access()
+ : logic_error( "bad optional access" ) {}
+};
+
+/// optional
+
+template< typename T>
+class optional
+{
+private:
+ typedef void (optional::*safe_bool)() const;
+
+public:
+ typedef T value_type;
+
+ optional_constexpr optional() optional_noexcept
+ : has_value_( false )
+ , contained()
+ {}
+
+ optional_constexpr optional( nullopt_t ) optional_noexcept
+ : has_value_( false )
+ , contained()
+ {}
+
+ optional( optional const & rhs )
+ : has_value_( rhs.has_value() )
+ {
+ if ( rhs.has_value() )
+ contained.construct_value( rhs.contained.value() );
+ }
+
+#if optional_CPP11_OR_GREATER
+ optional_constexpr14 optional( optional && rhs ) noexcept( std::is_nothrow_move_constructible<T>::value )
+ : has_value_( rhs.has_value() )
+ {
+ if ( rhs.has_value() )
+ contained.construct_value( std::move( rhs.contained.value() ) );
+ }
+#endif
+
+ optional_constexpr optional( value_type const & value )
+ : has_value_( true )
+ , contained( value )
+ {}
+
+#if optional_CPP11_OR_GREATER
+
+ optional_constexpr optional( value_type && value )
+ : has_value_( true )
+ , contained( std::move( value ) )
+ {}
+
+ template< class... Args >
+ optional_constexpr explicit optional( nonstd_lite_in_place_type_t(T), Args&&... args )
+ : has_value_( true )
+ , contained( T( std::forward<Args>(args)...) )
+ {}
+
+ template< class U, class... Args >
+ optional_constexpr explicit optional( nonstd_lite_in_place_type_t(T), std::initializer_list<U> il, Args&&... args )
+ : has_value_( true )
+ , contained( T( il, std::forward<Args>(args)...) )
+ {}
+
+#endif // optional_CPP11_OR_GREATER
+
+ ~optional()
+ {
+ if ( has_value() )
+ contained.destruct_value();
+ }
+
+ // assignment
+
+ optional & operator=( nullopt_t ) optional_noexcept
+ {
+ reset();
+ return *this;
+ }
+
+ optional & operator=( optional const & rhs )
+#if optional_CPP11_OR_GREATER
+ noexcept( std::is_nothrow_move_assignable<T>::value && std::is_nothrow_move_constructible<T>::value )
+#endif
+ {
+ if ( has_value() == true && rhs.has_value() == false ) reset();
+ else if ( has_value() == false && rhs.has_value() == true ) initialize( *rhs );
+ else if ( has_value() == true && rhs.has_value() == true ) contained.value() = *rhs;
+ return *this;
+ }
+
+#if optional_CPP11_OR_GREATER
+
+ optional & operator=( optional && rhs ) noexcept
+ {
+ if ( has_value() == true && rhs.has_value() == false ) reset();
+ else if ( has_value() == false && rhs.has_value() == true ) initialize( std::move( *rhs ) );
+ else if ( has_value() == true && rhs.has_value() == true ) contained.value() = std::move( *rhs );
+ return *this;
+ }
+
+ template< class U,
+ typename = typename std::enable_if< std::is_same< typename std::decay<U>::type, T>::value >::type >
+ optional & operator=( U && v )
+ {
+ if ( has_value() ) contained.value() = std::forward<U>( v );
+ else initialize( T( std::forward<U>( v ) ) );
+ return *this;
+ }
+
+ template< class... Args >
+ void emplace( Args&&... args )
+ {
+ *this = nullopt;
+ initialize( T( std::forward<Args>(args)...) );
+ }
+
+ template< class U, class... Args >
+ void emplace( std::initializer_list<U> il, Args&&... args )
+ {
+ *this = nullopt;
+ initialize( T( il, std::forward<Args>(args)...) );
+ }
+
+#endif // optional_CPP11_OR_GREATER
+
+ // swap
+
+ void swap( optional & rhs )
+#if optional_CPP11_OR_GREATER
+ noexcept( std::is_nothrow_move_constructible<T>::value && noexcept( std::swap( std::declval<T&>(), std::declval<T&>() ) ) )
+#endif
+ {
+ using std::swap;
+ if ( has_value() == true && rhs.has_value() == true ) { swap( **this, *rhs ); }
+ else if ( has_value() == false && rhs.has_value() == true ) { initialize( *rhs ); rhs.reset(); }
+ else if ( has_value() == true && rhs.has_value() == false ) { rhs.initialize( **this ); reset(); }
+ }
+
+ // observers
+
+ optional_constexpr value_type const * operator ->() const
+ {
+ return assert( has_value() ),
+ contained.value_ptr();
+ }
+
+ optional_constexpr14 value_type * operator ->()
+ {
+ return assert( has_value() ),
+ contained.value_ptr();
+ }
+
+ optional_constexpr value_type const & operator *() const optional_ref_qual
+ {
+ return assert( has_value() ),
+ contained.value();
+ }
+
+ optional_constexpr14 value_type & operator *() optional_ref_qual
+ {
+ return assert( has_value() ),
+ contained.value();
+ }
+
+#if optional_CPP11_OR_GREATER
+
+ optional_constexpr value_type const && operator *() const optional_refref_qual
+ {
+ return assert( has_value() ),
+ std::move( contained.value() );
+ }
+
+ optional_constexpr14 value_type && operator *() optional_refref_qual
+ {
+ return assert( has_value() ),
+ std::move( contained.value() );
+ }
+
+#endif
+
+#if optional_CPP11_OR_GREATER
+ optional_constexpr explicit operator bool() const optional_noexcept
+ {
+ return has_value();
+ }
+#else
+ optional_constexpr operator safe_bool() const optional_noexcept
+ {
+ return has_value() ? &optional::this_type_does_not_support_comparisons : 0;
+ }
+#endif
+
+ optional_constexpr bool has_value() const optional_noexcept
+ {
+ return has_value_;
+ }
+
+ optional_constexpr14 value_type const & value() const optional_ref_qual
+ {
+ if ( ! has_value() )
+ throw bad_optional_access();
+
+ return contained.value();
+ }
+
+ optional_constexpr14 value_type & value() optional_ref_qual
+ {
+ if ( ! has_value() )
+ throw bad_optional_access();
+
+ return contained.value();
+ }
+
+#if optional_HAVE( REF_QUALIFIER )
+
+ optional_constexpr14 value_type const && value() const optional_refref_qual
+ {
+ if ( ! has_value() )
+ throw bad_optional_access();
+
+ return std::move( contained.value() );
+ }
+
+ optional_constexpr14 value_type && value() optional_refref_qual
+ {
+ if ( ! has_value() )
+ throw bad_optional_access();
+
+ return std::move( contained.value() );
+ }
+
+#endif
+
+#if optional_CPP11_OR_GREATER
+
+ template< class U >
+ optional_constexpr value_type value_or( U && v ) const optional_ref_qual
+ {
+ return has_value() ? contained.value() : static_cast<T>(std::forward<U>( v ) );
+ }
+
+ template< class U >
+ optional_constexpr value_type value_or( U && v ) const optional_refref_qual
+ {
+ return has_value() ? std::move( contained.value() ) : static_cast<T>(std::forward<U>( v ) );
+ }
+
+#else
+
+ template< class U >
+ optional_constexpr value_type value_or( U const & v ) const
+ {
+ return has_value() ? contained.value() : static_cast<value_type>( v );
+ }
+
+#endif // optional_CPP11_OR_GREATER
+
+ // modifiers
+
+ void reset() optional_noexcept
+ {
+ if ( has_value() )
+ contained.destruct_value();
+
+ has_value_ = false;
+ }
+
+private:
+ void this_type_does_not_support_comparisons() const {}
+
+ template< typename V >
+ void initialize( V const & value )
+ {
+ assert( ! has_value() );
+ contained.construct_value( value );
+ has_value_ = true;
+ }
+
+#if optional_CPP11_OR_GREATER
+ template< typename V >
+ void initialize( V && value )
+ {
+ assert( ! has_value() );
+ contained.construct_value( std::move( value ) );
+ has_value_ = true;
+ }
+#endif
+
+private:
+ bool has_value_;
+ detail::storage_t< value_type > contained;
+
+};
+
+// Relational operators
+
+template< typename T, typename U >
+inline optional_constexpr bool operator==( optional<T> const & x, optional<U> const & y )
+{
+ return bool(x) != bool(y) ? false : !bool( x ) ? true : *x == *y;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator!=( optional<T> const & x, optional<U> const & y )
+{
+ return !(x == y);
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<( optional<T> const & x, optional<U> const & y )
+{
+ return (!y) ? false : (!x) ? true : *x < *y;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>( optional<T> const & x, optional<U> const & y )
+{
+ return (y < x);
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<=( optional<T> const & x, optional<U> const & y )
+{
+ return !(y < x);
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>=( optional<T> const & x, optional<U> const & y )
+{
+ return !(x < y);
+}
+
+// Comparison with nullopt
+
+template< typename T >
+inline optional_constexpr bool operator==( optional<T> const & x, nullopt_t ) optional_noexcept
+{
+ return (!x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator==( nullopt_t, optional<T> const & x ) optional_noexcept
+{
+ return (!x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator!=( optional<T> const & x, nullopt_t ) optional_noexcept
+{
+ return bool(x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator!=( nullopt_t, optional<T> const & x ) optional_noexcept
+{
+ return bool(x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator<( optional<T> const &, nullopt_t ) optional_noexcept
+{
+ return false;
+}
+
+template< typename T >
+inline optional_constexpr bool operator<( nullopt_t, optional<T> const & x ) optional_noexcept
+{
+ return bool(x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator<=( optional<T> const & x, nullopt_t ) optional_noexcept
+{
+ return (!x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator<=( nullopt_t, optional<T> const & ) optional_noexcept
+{
+ return true;
+}
+
+template< typename T >
+inline optional_constexpr bool operator>( optional<T> const & x, nullopt_t ) optional_noexcept
+{
+ return bool(x);
+}
+
+template< typename T >
+inline optional_constexpr bool operator>( nullopt_t, optional<T> const & ) optional_noexcept
+{
+ return false;
+}
+
+template< typename T >
+inline optional_constexpr bool operator>=( optional<T> const &, nullopt_t ) optional_noexcept
+{
+ return true;
+}
+
+template< typename T >
+inline optional_constexpr bool operator>=( nullopt_t, optional<T> const & x ) optional_noexcept
+{
+ return (!x);
+}
+
+// Comparison with T
+
+template< typename T, typename U >
+inline optional_constexpr bool operator==( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x == v : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator==( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v == *x : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator!=( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x != v : true;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator!=( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v != *x : true;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x < v : true;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v < *x : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<=( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x <= v : true;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator<=( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v <= *x : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x > v : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v > *x : true;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>=( optional<T> const & x, U const & v )
+{
+ return bool(x) ? *x >= v : false;
+}
+
+template< typename T, typename U >
+inline optional_constexpr bool operator>=( U const & v, optional<T> const & x )
+{
+ return bool(x) ? v >= *x : true;
+}
+
+// Specialized algorithms
+
+template< typename T >
+void swap( optional<T> & x, optional<T> & y )
+#if optional_CPP11_OR_GREATER
+ noexcept( noexcept( x.swap(y) ) )
+#endif
+{
+ x.swap( y );
+}
+
+#if optional_CPP11_OR_GREATER
+
+template< class T >
+optional_constexpr optional< typename std::decay<T>::type > make_optional( T && v )
+{
+ return optional< typename std::decay<T>::type >( std::forward<T>( v ) );
+}
+
+template< class T, class...Args >
+optional_constexpr optional<T> make_optional( Args&&... args )
+{
+ return optional<T>( in_place, std::forward<Args>(args)...);
+}
+
+template< class T, class U, class... Args >
+optional_constexpr optional<T> make_optional( std::initializer_list<U> il, Args&&... args )
+{
+ return optional<T>( in_place, il, std::forward<Args>(args)...);
+}
+
+#else
+
+template< typename T >
+optional<T> make_optional( T const & v )
+{
+ return optional<T>( v );
+}
+
+#endif // optional_CPP11_OR_GREATER
+
+} // namespace optional
+
+using namespace optional_lite;
+
+} // namespace nonstd
+
+#if optional_CPP11_OR_GREATER
+
+// specialize the std::hash algorithm:
+
+namespace std {
+
+template< class T >
+struct hash< nonstd::optional<T> >
+{
+public:
+ std::size_t operator()( nonstd::optional<T> const & v ) const optional_noexcept
+ {
+ return bool( v ) ? hash<T>()( *v ) : 0;
+ }
+};
+
+} //namespace std
+
+#endif // optional_CPP11_OR_GREATER
+
+#ifdef __clang__
+# pragma clang diagnostic pop
+#elif defined __GNUC__
+# pragma GCC diagnostic pop
+#endif
+
+#endif // have C++17 std::optional
+
+#endif // NONSTD_OPTIONAL_LITE_HPP