sneedmc/libraries/optional-bare/include/nonstd/optional

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//
// Copyright 2017-2019 by Martin Moene
//
// https://github.com/martinmoene/optional-bare
//
// 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)
#ifndef NONSTD_OPTIONAL_BARE_HPP
#define NONSTD_OPTIONAL_BARE_HPP
#define optional_bare_MAJOR 1
#define optional_bare_MINOR 1
#define optional_bare_PATCH 0
#define optional_bare_VERSION optional_STRINGIFY(optional_bare_MAJOR) "." optional_STRINGIFY(optional_bare_MINOR) "." optional_STRINGIFY(optional_bare_PATCH)
#define optional_STRINGIFY( x ) optional_STRINGIFY_( x )
#define optional_STRINGIFY_( x ) #x
// optional-bare 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 _MSC_VER
# include <cstddef> // for _HAS_EXCEPTIONS
# endif
# if _MSC_VER
# include <cstddef> // for _HAS_EXCEPTIONS
# endif
# if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || (_HAS_EXCEPTIONS)
# 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_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) )
//
// Using std::optional:
//
#if optional_USES_STD_OPTIONAL
#include <optional>
#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;
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>
#if ! optional_CONFIG_NO_EXCEPTIONS
# include <stdexcept>
#endif
namespace nonstd { namespace optional_bare {
// type for nullopt
struct nullopt_t
{
struct init{};
nullopt_t( init ) {}
};
// extra parenthesis to prevent the most vexing parse:
const nullopt_t nullopt(( nullopt_t::init() ));
// 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
// Simplistic optional: requires T to be default constructible, copyable.
template< typename T >
class optional
{
private:
typedef void (optional::*safe_bool)() const;
public:
typedef T value_type;
optional()
: has_value_( false )
{}
optional( nullopt_t )
: has_value_( false )
{}
optional( T const & arg )
: has_value_( true )
, value_ ( arg )
{}
template< class U >
optional( optional<U> const & other )
: has_value_( other.has_value() )
, value_ ( other.value() )
{}
optional & operator=( nullopt_t )
{
reset();
return *this;
}
template< class U >
optional & operator=( optional<U> const & other )
{
has_value_ = other.has_value();
value_ = other.value();
return *this;
}
void swap( optional & rhs )
{
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
value_type const * operator->() const
{
return assert( has_value() ),
&value_;
}
value_type * operator->()
{
return assert( has_value() ),
&value_;
}
value_type const & operator*() const
{
return assert( has_value() ),
value_;
}
value_type & operator*()
{
return assert( has_value() ),
value_;
}
#if optional_CPP11_OR_GREATER
explicit operator bool() const
{
return has_value();
}
#else
operator safe_bool() const
{
return has_value() ? &optional::this_type_does_not_support_comparisons : 0;
}
#endif
bool has_value() const
{
return has_value_;
}
value_type const & value() const
{
#if optional_CONFIG_NO_EXCEPTIONS
assert( has_value() );
#else
if ( ! has_value() )
throw bad_optional_access();
#endif
return value_;
}
value_type & value()
{
#if optional_CONFIG_NO_EXCEPTIONS
assert( has_value() );
#else
if ( ! has_value() )
throw bad_optional_access();
#endif
return value_;
}
template< class U >
value_type value_or( U const & v ) const
{
return has_value() ? value() : static_cast<value_type>( v );
}
// modifiers
void reset()
{
has_value_ = false;
}
private:
void this_type_does_not_support_comparisons() const {}
template< typename V >
void initialize( V const & value )
{
assert( ! has_value() );
value_ = value;
has_value_ = true;
}
private:
bool has_value_;
value_type value_;
};
// Relational operators
template< typename T, typename U >
inline bool operator==( optional<T> const & x, optional<U> const & y )
{
return bool(x) != bool(y) ? false : bool(x) == false ? true : *x == *y;
}
template< typename T, typename U >
inline bool operator!=( optional<T> const & x, optional<U> const & y )
{
return !(x == y);
}
template< typename T, typename U >
inline bool operator<( optional<T> const & x, optional<U> const & y )
{
return (!y) ? false : (!x) ? true : *x < *y;
}
template< typename T, typename U >
inline bool operator>( optional<T> const & x, optional<U> const & y )
{
return (y < x);
}
template< typename T, typename U >
inline bool operator<=( optional<T> const & x, optional<U> const & y )
{
return !(y < x);
}
template< typename T, typename U >
inline bool operator>=( optional<T> const & x, optional<U> const & y )
{
return !(x < y);
}
// Comparison with nullopt
template< typename T >
inline bool operator==( optional<T> const & x, nullopt_t )
{
return (!x);
}
template< typename T >
inline bool operator==( nullopt_t, optional<T> const & x )
{
return (!x);
}
template< typename T >
inline bool operator!=( optional<T> const & x, nullopt_t )
{
return bool(x);
}
template< typename T >
inline bool operator!=( nullopt_t, optional<T> const & x )
{
return bool(x);
}
template< typename T >
inline bool operator<( optional<T> const &, nullopt_t )
{
return false;
}
template< typename T >
inline bool operator<( nullopt_t, optional<T> const & x )
{
return bool(x);
}
template< typename T >
inline bool operator<=( optional<T> const & x, nullopt_t )
{
return (!x);
}
template< typename T >
inline bool operator<=( nullopt_t, optional<T> const & )
{
return true;
}
template< typename T >
inline bool operator>( optional<T> const & x, nullopt_t )
{
return bool(x);
}
template< typename T >
inline bool operator>( nullopt_t, optional<T> const & )
{
return false;
}
template< typename T >
inline bool operator>=( optional<T> const &, nullopt_t )
{
return true;
}
template< typename T >
inline bool operator>=( nullopt_t, optional<T> const & x )
{
return (!x);
}
// Comparison with T
template< typename T, typename U >
inline bool operator==( optional<T> const & x, U const & v )
{
return bool(x) ? *x == v : false;
}
template< typename T, typename U >
inline bool operator==( U const & v, optional<T> const & x )
{
return bool(x) ? v == *x : false;
}
template< typename T, typename U >
inline bool operator!=( optional<T> const & x, U const & v )
{
return bool(x) ? *x != v : true;
}
template< typename T, typename U >
inline bool operator!=( U const & v, optional<T> const & x )
{
return bool(x) ? v != *x : true;
}
template< typename T, typename U >
inline bool operator<( optional<T> const & x, U const & v )
{
return bool(x) ? *x < v : true;
}
template< typename T, typename U >
inline bool operator<( U const & v, optional<T> const & x )
{
return bool(x) ? v < *x : false;
}
template< typename T, typename U >
inline bool operator<=( optional<T> const & x, U const & v )
{
return bool(x) ? *x <= v : true;
}
template< typename T, typename U >
inline bool operator<=( U const & v, optional<T> const & x )
{
return bool(x) ? v <= *x : false;
}
template< typename T, typename U >
inline bool operator>( optional<T> const & x, U const & v )
{
return bool(x) ? *x > v : false;
}
template< typename T, typename U >
inline bool operator>( U const & v, optional<T> const & x )
{
return bool(x) ? v > *x : true;
}
template< typename T, typename U >
inline bool operator>=( optional<T> const & x, U const & v )
{
return bool(x) ? *x >= v : false;
}
template< typename T, typename U >
inline 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 )
{
x.swap( y );
}
// Convenience function to create an optional.
template< typename T >
inline optional<T> make_optional( T const & v )
{
return optional<T>( v );
}
} // namespace optional-bare
using namespace optional_bare;
} // namespace nonstd
#endif // optional_USES_STD_OPTIONAL
#endif // NONSTD_OPTIONAL_BARE_HPP