lagoon/range/extract.hpp

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#ifndef LAGOON_RANGE_EXTRACT_1011291729_HPP
#define LAGOON_RANGE_EXTRACT_1011291729_HPP

#include <lagoon/lagoon_fwd.hpp>
#include <lagoon/range/only_if.hpp>
#include <lagoon/range/transform.hpp>

LAGOON_NAMESPACE_BEGIN
namespace aux {

template <class Interface>
struct mo_has_intf
{
    template <class MetaObject>
    inline bool operator()(const MetaObject& metaobject) const
    {
        return metaobject.template is<Interface>();
    }
};

template <class Interface>
struct mo_query_intf
{
    template <class MetaObject>
    inline auto operator()(const MetaObject& metaobject) const ->
        decltype(metaobject.template as<Interface>())
    {
        return metaobject.template as<Interface>();
    }
};

} // namespace aux

#ifdef MIRROR_DOCUMENTATION_ONLY


template <class Interface, class Range>
UnspecifiedRange<Interface> extract(const Range& metaobjects);
#else
template <class Interface, class Range>
auto extract(const Range& metaobjects) ->
decltype(
    transform(
        only_if(
            metaobjects,
            aux::mo_has_intf<Interface>()
        ),
        aux::mo_query_intf<Interface>()
    )
)
{
    return transform(
        only_if(
            metaobjects,
            aux::mo_has_intf<Interface>()
        ),
        aux::mo_query_intf<Interface>()
    );
}
#endif

LAGOON_NAMESPACE_END

#endif //include guard