channelutils.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/

#pragma once

#include <util/sll/typegetter.h>
#include "channel.h"
#include "inparallel.h"
#include "task.h"

namespace LC::Util
{
    template<typename T>
    Channel_ptr<T> MergeChannels (QVector<Channel_ptr<T>> channels)
    {
        auto output = std::make_shared<Channel<T>> ();
        [] (Channel_ptr<T> output, QVector<Channel_ptr<T>> channels) -> Task<void>
        {
            co_await InParallel (channels, [] (auto inChan, auto outChan) -> Task<void>
                    {
                        while (auto value = co_await *inChan)
                            outChan->Send (std::move (*value));
                    }, output);
            output->Close ();
        } (output, std::move (channels));
        return output;
    }

    template<
            typename T = void,
            typename F,
            typename... Args,
            typename ItemType =
                std::conditional_t<
                    !std::is_same_v<T, void>,
                    T,
                    typename ArgType_t<F, 0>::element_type::ItemType_t
                >
        >
    Channel_ptr<ItemType> WithChannel (F&& f, Args&&... args)
    {
        auto output = std::make_shared<Channel<ItemType>> ();
        [] (auto f, Channel_ptr<ItemType> output, auto... args) -> Task<void>
        {
            co_await std::invoke (f, output, args...);
            output->Close ();
        } (std::forward<F> (f), output, std::forward<Args> (args)...);
        return output;
    }

    template<
            typename F,
            typename Conv = std::identity,
            typename... Args,
            typename ItemType = RetType_t<F>::ResultType_t,
            typename ConvertedType = std::invoke_result_t<Conv, ItemType>
        >
    Channel_ptr<ConvertedType> ChannelFromSingleResult (F&& f, Conv&& conv, Args&&... args)
    {
        auto output = std::make_shared<Channel<ConvertedType>> ();
        [] (auto f, auto conv, Channel_ptr<ConvertedType> output, auto... args) -> Task<void>
        {
            auto res = co_await std::invoke (f, args...);
            output->Send (conv (std::move (res)));
            output->Close ();
        } (std::forward<F> (f), std::forward<Conv> (conv), output, std::forward<Args> (args)...);
        return output;
    }
}