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// Copyright (C) 2015-2016 Andrzej Krzemienski.
//
// Use, modification, and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// akrzemi1@gmail.com
#ifndef BOOST_OPTIONAL_DETAIL_OPTIONAL_REFERENCE_SPEC_AJK_03OCT2015_HPP
#define BOOST_OPTIONAL_DETAIL_OPTIONAL_REFERENCE_SPEC_AJK_03OCT2015_HPP
#ifdef BOOST_OPTIONAL_CONFIG_NO_PROPER_ASSIGN_FROM_CONST_INT
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_const.hpp>
#endif
# if 1
namespace boost {
namespace detail {
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
template <class From>
void prevent_binding_rvalue()
{
#ifndef BOOST_OPTIONAL_CONFIG_ALLOW_BINDING_TO_RVALUES
BOOST_STATIC_ASSERT_MSG(boost::is_lvalue_reference<From>::value,
"binding rvalue references to optional lvalue references is disallowed");
#endif
}
template <class T>
BOOST_DEDUCED_TYPENAME boost::remove_reference<T>::type& forward_reference(T&& r)
{
BOOST_STATIC_ASSERT_MSG(boost::is_lvalue_reference<T>::value,
"binding rvalue references to optional lvalue references is disallowed");
return boost::forward<T>(r);
}
#endif // BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
template <class T>
struct is_const_integral
{
static const bool value = boost::is_const<T>::value && boost::is_integral<T>::value;
};
template <class T>
struct is_const_integral_bad_for_conversion
{
#if (!defined BOOST_OPTIONAL_CONFIG_ALLOW_BINDING_TO_RVALUES) && (defined BOOST_OPTIONAL_CONFIG_NO_PROPER_CONVERT_FROM_CONST_INT)
static const bool value = boost::is_const<T>::value && boost::is_integral<T>::value;
#else
static const bool value = false;
#endif
};
template <class From>
void prevent_assignment_from_false_const_integral()
{
#ifndef BOOST_OPTIONAL_CONFIG_ALLOW_BINDING_TO_RVALUES
#ifdef BOOST_OPTIONAL_CONFIG_NO_PROPER_ASSIGN_FROM_CONST_INT
// MSVC compiler without rvalue refernces: we need to disable the asignment from
// const integral lvalue reference, as it may be an invalid temporary
BOOST_STATIC_ASSERT_MSG(!is_const_integral<From>::value,
"binding const lvalue references to integral types is disabled in this compiler");
#endif
#endif
}
template <class T>
struct is_optional_
{
static const bool value = false;
};
template <class U>
struct is_optional_< ::boost::optional<U> >
{
static const bool value = true;
};
template <class T>
struct is_no_optional
{
static const bool value = !is_optional_<BOOST_DEDUCED_TYPENAME boost::decay<T>::type>::value;
};
template <class T, class U>
struct is_same_decayed
{
static const bool value = ::boost::is_same<T, BOOST_DEDUCED_TYPENAME ::boost::remove_reference<U>::type>::value
|| ::boost::is_same<T, const BOOST_DEDUCED_TYPENAME ::boost::remove_reference<U>::type>::value;
};
template <class T, class U>
struct no_unboxing_cond
{
static const bool value = is_no_optional<U>::value && !is_same_decayed<T, U>::value;
};
} // namespace detail
template <class T>
class optional<T&> : public optional_detail::optional_tag
{
T* ptr_;
public:
typedef T& value_type;
typedef T& reference_type;
typedef T& reference_const_type;
typedef T& rval_reference_type;
typedef T* pointer_type;
typedef T* pointer_const_type;
optional() BOOST_NOEXCEPT : ptr_() {}
optional(none_t) BOOST_NOEXCEPT : ptr_() {}
template <class U>
explicit optional(const optional<U&>& rhs) BOOST_NOEXCEPT : ptr_(rhs.get_ptr()) {}
optional(const optional& rhs) BOOST_NOEXCEPT : ptr_(rhs.get_ptr()) {}
// the following two implement a 'conditionally explicit' constructor: condition is a hack for buggy compilers with srewed conversion construction from const int
template <class U>
explicit optional(U& rhs, BOOST_DEDUCED_TYPENAME boost::enable_if_c<detail::is_same_decayed<T, U>::value && detail::is_const_integral_bad_for_conversion<U>::value>::type* = 0) BOOST_NOEXCEPT
: ptr_(boost::addressof(rhs)) {}
template <class U>
optional(U& rhs, BOOST_DEDUCED_TYPENAME boost::enable_if_c<detail::is_same_decayed<T, U>::value && !detail::is_const_integral_bad_for_conversion<U>::value>::type* = 0) BOOST_NOEXCEPT
: ptr_(boost::addressof(rhs)) {}
optional& operator=(const optional& rhs) BOOST_NOEXCEPT { ptr_ = rhs.get_ptr(); return *this; }
template <class U>
optional& operator=(const optional<U&>& rhs) BOOST_NOEXCEPT { ptr_ = rhs.get_ptr(); return *this; }
optional& operator=(none_t) BOOST_NOEXCEPT { ptr_ = 0; return *this; }
void swap(optional& rhs) BOOST_NOEXCEPT { std::swap(ptr_, rhs.ptr_); }
T& get() const { BOOST_ASSERT(ptr_); return *ptr_; }
T* get_ptr() const BOOST_NOEXCEPT { return ptr_; }
T* operator->() const { BOOST_ASSERT(ptr_); return ptr_; }
T& operator*() const { BOOST_ASSERT(ptr_); return *ptr_; }
T& value() const { return ptr_ ? *ptr_ : (throw_exception(bad_optional_access()), *ptr_); }
bool operator!() const BOOST_NOEXCEPT { return ptr_ == 0; }
BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()
void reset() BOOST_NOEXCEPT { ptr_ = 0; }
bool is_initialized() const BOOST_NOEXCEPT { return ptr_ != 0; }
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
optional(T&& /* rhs */) BOOST_NOEXCEPT { detail::prevent_binding_rvalue<T&&>(); }
template <class R>
optional(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::no_unboxing_cond<T, R> >::type* = 0) BOOST_NOEXCEPT
: ptr_(boost::addressof(r)) { detail::prevent_binding_rvalue<R>(); }
template <class R>
optional(bool cond, R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) BOOST_NOEXCEPT
: ptr_(cond ? boost::addressof(r) : 0) { detail::prevent_binding_rvalue<R>(); }
template <class R>
BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R>, optional<T&>&>::type
operator=(R&& r) BOOST_NOEXCEPT { detail::prevent_binding_rvalue<R>(); ptr_ = boost::addressof(r); return *this; }
template <class R>
void emplace(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) BOOST_NOEXCEPT
{ detail::prevent_binding_rvalue<R>(); ptr_ = boost::addressof(r); }
template <class R>
T& get_value_or(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) const BOOST_NOEXCEPT
{ detail::prevent_binding_rvalue<R>(); return ptr_ ? *ptr_ : r; }
template <class R>
T& value_or(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) const BOOST_NOEXCEPT
{ detail::prevent_binding_rvalue<R>(); return ptr_ ? *ptr_ : r; }
template <class R>
void reset(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) BOOST_NOEXCEPT
{ detail::prevent_binding_rvalue<R>(); ptr_ = boost::addressof(r); }
template <class F>
T& value_or_eval(F f) const { return ptr_ ? *ptr_ : detail::forward_reference(f()); }
#else // BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// the following two implement a 'conditionally explicit' constructor
template <class U>
explicit optional(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if_c<detail::no_unboxing_cond<T, U>::value && detail::is_const_integral_bad_for_conversion<U>::value >::type* = 0) BOOST_NOEXCEPT
: ptr_(boost::addressof(v)) { }
template <class U>
optional(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if_c<detail::no_unboxing_cond<T, U>::value && !detail::is_const_integral_bad_for_conversion<U>::value >::type* = 0) BOOST_NOEXCEPT
: ptr_(boost::addressof(v)) { }
template <class U>
optional(bool cond, U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) BOOST_NOEXCEPT : ptr_(cond ? boost::addressof(v) : 0) {}
template <class U>
BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U>, optional<T&>&>::type
operator=(U& v) BOOST_NOEXCEPT
{
detail::prevent_assignment_from_false_const_integral<U>();
ptr_ = boost::addressof(v); return *this;
}
template <class U>
void emplace(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) BOOST_NOEXCEPT
{ ptr_ = boost::addressof(v); }
template <class U>
T& get_value_or(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) const BOOST_NOEXCEPT
{ return ptr_ ? *ptr_ : v; }
template <class U>
T& value_or(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) const BOOST_NOEXCEPT
{ return ptr_ ? *ptr_ : v; }
template <class U>
void reset(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) BOOST_NOEXCEPT
{ ptr_ = boost::addressof(v); }
template <class F>
T& value_or_eval(F f) const { return ptr_ ? *ptr_ : f(); }
#endif // BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
};
template <class T>
void swap ( optional<T&>& x, optional<T&>& y) BOOST_NOEXCEPT
{
x.swap(y);
}
} // namespace boost
#endif // 1/0
#endif // header guard
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