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Cleaner handling of explicit U to T conversions

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This commit is contained in:
Andrzej Krzemienski
2014-06-20 11:38:57 +02:00
parent 4af83ecf83
commit 4cbb67e505
5 changed files with 68 additions and 83 deletions
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59
include/boost/optional/optional.hpp
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@ -112,28 +112,6 @@ class typed_in_place_factory_base ;
template<class T> void swap ( optional<T>& x, optional<T>& y );
namespace optional_detail {
// converts type U to type T using only implicit conversions/constructors
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename TT, typename UU>
TT convert(UU && u)
{
return forward<UU>(u);
}
#else
template <typename TT, typename UU>
TT convert(const UU& u)
{
return u;
}
template <typename TT, typename UU>
TT convert(UU& u)
{
return u;
}
#endif
// This local class is used instead of that in "aligned_storage.hpp"
// because I've found the 'official' class to ICE BCB5.5
// when some types are used with optional<>
@ -1082,25 +1060,37 @@ class optional : public optional_detail::optional_base<T>
template <class U>
value_type value_or ( U&& v ) const&
{
return this->is_initialized() ? get() : optional_detail::convert<value_type>(boost::forward<U>(v));
if (this->is_initialized())
return get();
else
return boost::forward<U>(v);
}
template <class U>
value_type value_or ( U&& v ) &&
{
return this->is_initialized() ? boost::move(get()) : optional_detail::convert<value_type>(boost::forward<U>(v));
if (this->is_initialized())
return boost::move(get());
else
return boost::forward<U>(v);
}
#elif !defined BOOST_NO_CXX11_RVALUE_REFERENCES
template <class U>
value_type value_or ( U&& v ) const
{
return this->is_initialized() ? get() : optional_detail::convert<value_type>(boost::forward<U>(v));
{
if (this->is_initialized())
return get();
else
return boost::forward<U>(v);
}
#else
template <class U>
value_type value_or ( U const& v ) const
{
return this->is_initialized() ? get() : optional_detail::convert<value_type>(v);
if (this->is_initialized())
return get();
else
return v;
}
#endif
@ -1109,19 +1099,28 @@ class optional : public optional_detail::optional_base<T>
template <typename F>
value_type value_or_eval ( F f ) const&
{
return this->is_initialized() ? get() : optional_detail::convert<value_type>(f());
if (this->is_initialized())
return get();
else
return f();
}
template <typename F>
value_type value_or_eval ( F f ) &&
{
return this->is_initialized() ? boost::move(get()) : optional_detail::convert<value_type>(f());
if (this->is_initialized())
return boost::move(get());
else
return f();
}
#else
template <typename F>
value_type value_or_eval ( F f ) const
{
return this->is_initialized() ? get() : optional_detail::convert<value_type>(f());
if (this->is_initialized())
return get();
else
return f();
}
#endif