task.hpp

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// task.hpp v1.0
/*
 *  Copyright (c) 2007 Leigh Johnston.
 *
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are
 *  met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 *     * Neither the name of Leigh Johnston nor the names of any
 *       other contributors to this software may be used to endorse or
 *       promote products derived from this software without specific prior
 *       written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 *  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 *  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 *  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 *  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 *  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#pragma once
 
#include <neolib/neolib.hpp>
#include <future>
#include <atomic>
#include <neolib/core/lifetime.hpp>
#include <neolib/task/i_task.hpp>
 
namespace neolib
{
    template <typename Base = i_task>
    class task : public Base
    {
        // construction
    public:
        task(const std::string& aName = std::string{}) : iName{ aName }, iCancelled{ false }
        {
        }
        // operations
    public:
        const std::string& name() const override
        {
            return iName;
        }
        // implementation
    public:
        bool do_work(yield_type aYieldType = yield_type::NoYield) override
        {
            return false;
        }
        void cancel() noexcept override
        {
            iCancelled = true;
        }
        bool cancelled() const override
        {
            return iCancelled;
        }
        // attributes
    private:
        std::string iName;
        std::atomic<bool> iCancelled;
    };
 
    template <typename T>
    class function_task : public task<>
    {
    public:
        function_task(std::function<T()> aFunction) : task{}, iFunction{ aFunction }
        {
        }
    public:
        std::future<T> get_future()
        {
            return iPromise.get_future();
        }
    public:
        const std::string& name() const override
        {
            static std::string sName = "neolib::function_task";
            return sName;
        }
        void run(yield_type) override
        {
            iPromise.set_value(iFunction());
        }
    private:
        std::function<T()> iFunction;
        std::promise<T> iPromise;
    };
 
    template <>
    inline void function_task<void>::run(yield_type)
    {
        iFunction();
        iPromise.set_value();
    }
}