resourcefactorychain.h

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/********************************************************************************************
* Twitch Broadcasting SDK
*
* This software is supplied under the terms of a license agreement with Twitch Interactive, Inc. and
* may not be copied or used except in accordance with the terms of that agreement
* Copyright (c) 2012-2015 Twitch Interactive, Inc.
*********************************************************************************************/

#pragma once

#include <functional>
#include <memory>

namespace ttv
{
    template <typename RESOURCE, typename FACTORY>
    class ResourceFactoryChain
    {
    public:
        typedef std::function<TTV_ErrorCode(const std::shared_ptr<FACTORY>& factory, std::shared_ptr<RESOURCE>& result)> CreateFunc;
        typedef std::function<bool(const std::shared_ptr<FACTORY>& factory)> QueryFunc;

    public:
        ResourceFactoryChain(const std::string& name)
            : mName(name)
            , mRegisteredDefaults(false)
        {
        }

        virtual ~ResourceFactoryChain()
        {
        }

        virtual TTV_ErrorCode Register(const std::shared_ptr<FACTORY>& factory)
        {
            if (factory == nullptr)
            {
                ttv::trace::Message("Core", TTV_ML_ERROR, "ResourceFactoryChain::Register: null factory given");

                return TTV_EC_INVALID_ARG;
            }

            auto iter = std::find(mChain.begin(), mChain.end(), factory);
            if (iter != mChain.end())
            {
                ttv::trace::Message("Core", TTV_ML_ERROR, "ResourceFactoryChain::Register: factory already registered");

                return TTV_EC_INVALID_ARG;
            }

            mChain.insert(mChain.begin(), factory);

            return TTV_EC_SUCCESS;
        }

        virtual TTV_ErrorCode Unregister(const std::shared_ptr<FACTORY>& factory)
        {
            if (factory == nullptr)
            {
                ttv::trace::Message("Core", TTV_ML_ERROR, "ResourceFactoryChain::Unregister: null factory given");

                return TTV_EC_INVALID_ARG;
            }

            auto iter = std::find(mChain.begin(), mChain.end(), factory);
            if (iter == mChain.end())
            {
                ttv::trace::Message("Core", TTV_ML_ERROR, "ResourceFactoryChain::Register: factory not registered");

                return TTV_EC_INVALID_ARG;
            }

            mChain.erase(iter);

            return TTV_EC_SUCCESS;
        }

        virtual TTV_ErrorCode Create(const CreateFunc& createFunc, std::shared_ptr<RESOURCE>& result) const
        {
            result.reset();

            if (mChain.empty())
            {
                ttv::trace::Message("Core", TTV_ML_ERROR, "There are no %s factories registered", mName.c_str());
                return TTV_EC_NO_FACTORIES_REGISTERED;
            }

            auto copy = mChain;

            for (const auto& factory : copy)
            {
                TTV_ErrorCode ec = createFunc(factory, result);
                if (TTV_SUCCEEDED(ec) && result != nullptr)
                {
                    break;
                }
            }

            if (result != nullptr)
            {
                return TTV_EC_SUCCESS;
            }
            else
            {
                return TTV_EC_UNIMPLEMENTED;
            }
        }

        bool BoolQuery(const QueryFunc& queryFunc) const
        {
            auto copy = mChain;

            for (const auto& factory : copy)
            {
                if (queryFunc(factory))
                {
                    return true;
                }
            }

            return false;
        }

        void SetRegisteredDefaults()
        {
            mRegisteredDefaults = true;
        }

        bool RegisteredDefaults() const
        {
            return mRegisteredDefaults;
        }

        bool Empty() const
        {
            return mChain.empty();
        }

    protected:
        std::string mName;
        std::vector<std::shared_ptr<FACTORY>> mChain;
        bool mRegisteredDefaults;
    };
}