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added implementation and tests of flat_map()

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This commit is contained in:
Andrzej Krzemienski
2018-06-28 23:27:42 +02:00
parent 701afd43a4
commit 71d797b9ee
4 changed files with 340 additions and 1 deletions
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9
include/boost/optional/detail/optional_reference_spec.hpp
View File

@ -170,6 +170,15 @@ public:
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&&>(); }

55
include/boost/optional/optional.hpp
View File

@ -758,7 +758,16 @@ class optional_base : public optional_tag
storage_type m_storage ;
} ;
template <typename T>
struct optional_value_type
{
};
template <typename T>
struct optional_value_type< ::boost::optional<T> >
{
typedef T type;
};
#include <boost/optional/detail/optional_trivially_copyable_base.hpp>
@ -1351,6 +1360,33 @@ class optional
return none;
}
template <typename F>
optional<typename optional_detail::optional_value_type<typename boost::result_of<F(reference_type)>::type>::type> flat_map(F f) &
{
if (this->has_value())
return f(get());
else
return none;
}
template <typename F>
optional<typename optional_detail::optional_value_type<typename boost::result_of<F(reference_const_type)>::type>::type> flat_map(F f) const&
{
if (this->has_value())
return f(get());
else
return none;
}
template <typename F>
optional<typename optional_detail::optional_value_type<typename boost::result_of<F(reference_type_of_temporary_wrapper)>::type>::type> flat_map(F f) &&
{
if (this->has_value())
return f(boost::move(get()));
else
return none;
}
#else
template <typename F>
value_type value_or_eval ( F f ) const
@ -1378,6 +1414,25 @@ class optional
else
return none;
}
template <typename F>
optional<typename optional_detail::optional_value_type<typename boost::result_of<F(reference_type)>::type>::type> flat_map(F f)
{
if (this->has_value())
return f(get());
else
return none;
}
template <typename F>
optional<typename optional_detail::optional_value_type<typename boost::result_of<F(reference_const_type)>::type>::type> flat_map(F f) const
{
if (this->has_value())
return f(get());
else
return none;
}
#endif
bool has_value() const BOOST_NOEXCEPT { return this->is_initialized() ; }