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/******************************************************************************
* ____ _ _____ *
* / ___| / \ | ___| C++ *
* | | / _ \ | |_ Actor *
* | |___ / ___ \| _| Framework *
* \____/_/ \_|_| *
* *
* Copyright 2011-2018 Dominik Charousset *
* *
* Distributed under the terms and conditions of the BSD 3-Clause License or *
* (at your option) under the terms and conditions of the Boost Software *
* License 1.0. See accompanying files LICENSE and LICENSE_ALTERNATIVE. *
* *
* If you did not receive a copy of the license files, see *
* http://opensource.org/licenses/BSD-3-Clause and *
* http://www.boost.org/LICENSE_1_0.txt. *
******************************************************************************/
#pragma once
#include "caf/fwd.hpp"
#include "caf/detail/type_traits.hpp"
namespace caf {
/// Deduces the output type and the state type for a stream source from its
/// `pull` implementation.
template <class Pull>
struct stream_source_trait {
static constexpr bool valid = false;
using output = unit_t;
using state = unit_t;
};
template <class State, class T>
struct stream_source_trait<void (State&, downstream<T>&, size_t)> {
static constexpr bool valid = true;
using output = T;
using state = State;
};
/// Convenience alias for extracting the function signature from `Pull` and
/// passing it to `stream_source_trait`.
template <class Pull>
using stream_source_trait_t =
stream_source_trait<typename detail::get_callable_trait<Pull>::fun_sig>;
} // namespace caf
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