dispatch.h

 
#pragma once
 
#include "vari/bits/dispatch.h"
 
namespace vari
{
 
// Given `i` calls `Cnv` callable with `i` as _template argument_ and passes the result into best
// match of callable out of `fn` set.
//
// `i` has to fit in range 0..N-1, any other value is undefined behavior.
template < std::size_t N, typename Cnv, typename... Fn >
constexpr decltype( auto ) dispatch( index_type i, Cnv&& cnv, Fn&&... fn )
{
        using types = factory_result_types_t< N, Cnv >;
 
        typename _check_unique_invocability< types >::template with_pure_value< Fn... > _{};
 
        return _dispatch_index< 0, N >( i, [&]< index_type j >() -> decltype( auto ) {
                auto&& item = cnv.template operator()< j >();
 
                return _dispatch_fun( (decltype( item )&&) item, (Fn&&) fn... );
        } );
}
 
}  // namespace vari