EVOLUTION-MANAGER

Edit File: optional_reference_spec.hpp

// Copyright (C) 2015-2018 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 >
{
 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::type>::value
 || ::boost::is_same<T, const BOOST_DEDUCED_TYPENAME ::boost::remove_reference::type>::value;
 };

template <class T, class U>
struct no_unboxing_cond
{
 static const bool value = is_no_optional::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::value, bool>::type = true) 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::value, bool>::type = true) 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; }
 bool has_value() const BOOST_NOEXCEPT { return ptr_ != 0; }
 
 template <typename F>
 optional<typename boost::result_of<F(T&)>::type> map(F f) const
 {
 if (this->has_value())
 return f(this->get());
 else
 return none;
 }

template <typename F>
 optional<typename optional_detail::optional_value_type<typename boost::result_of<F(T&)>::type>::type> flat_map(F f) const
 {
 if (this->has_value())
 return f(get());
 else
 return none;
 }
 
#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>, bool>::type = true) 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>, bool>::type = true) 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>, bool>::type = true) 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>, bool>::type = true) 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>, bool>::type = true) 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>, bool>::type = true) 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::value, bool>::type = true) 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::value, bool>::type = true) BOOST_NOEXCEPT
 : ptr_(boost::addressof(v)) { }
 
 template <class U>
 optional(bool cond, U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional, bool>::type = true) BOOST_NOEXCEPT : ptr_(cond ? boost::addressof(v) : 0) {}

template <class U>
 BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional, optional<T&>&>::type
 operator=(U& v) BOOST_NOEXCEPT
 {
 detail::prevent_assignment_from_false_const_integral();
 ptr_ = boost::addressof(v); return *this;
 }

template <class U>
 void emplace(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional, bool>::type = true) 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, bool>::type = true) 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, bool>::type = true) const BOOST_NOEXCEPT
 { return ptr_ ? *ptr_ : v; }
 
 template <class U>
 void reset(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional, bool>::type = true) 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