TrinityCore/src/server/database/Database/QueryCallback.h

/*
 * Copyright (C) 2008-2016 TrinityCore <http://www.trinitycore.org/>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _QUERY_CALLBACK_H
#define _QUERY_CALLBACK_H

#include <future>
#include "QueryResult.h"

typedef std::future<QueryResult> QueryResultFuture;
typedef std::promise<QueryResult> QueryResultPromise;
typedef std::future<PreparedQueryResult> PreparedQueryResultFuture;
typedef std::promise<PreparedQueryResult> PreparedQueryResultPromise;

#define CALLBACK_STAGE_INVALID uint8(-1)

template <typename Result, typename ParamType, bool chain = false>
class QueryCallback
{
    public:
        QueryCallback() : _param(), _stage(chain ? 0 : CALLBACK_STAGE_INVALID)  { }

        //! The parameter of this function should be a resultset returned from either .AsyncQuery or .AsyncPQuery
        void SetFutureResult(std::future<Result> value)
        {
            _result = std::move(value);
        }

        std::future<Result>& GetFutureResult()
        {
            return _result;
        }

        bool IsReady()
        {
            return _result.valid() && _result.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
        }

        void GetResult(Result& res)
        {
            res = _result.get();
        }

        void FreeResult()
        {
            // Nothing to do here, the constructor of std::future will take care of the cleanup
        }

        void SetParam(ParamType value)
        {
            _param = value;
        }

        ParamType GetParam()
        {
            return _param;
        }

        //! Resets the stage of the callback chain
        void ResetStage()
        {
            if (!chain)
                return;

            _stage = 0;
        }

        //! Advances the callback chain to the next stage, so upper level code can act on its results accordingly
        void NextStage()
        {
            if (!chain)
                return;

            ++_stage;
        }

        //! Returns the callback stage (or CALLBACK_STAGE_INVALID if invalid)
        uint8 GetStage()
        {
            return _stage;
        }

        //! Resets all underlying variables (param, result and stage)
        void Reset()
        {
            SetParam(ParamType());
            FreeResult();
            ResetStage();
        }

    private:
        std::future<Result> _result;
        ParamType _param;
        uint8 _stage;

        QueryCallback(QueryCallback const& right) = delete;
        QueryCallback& operator=(QueryCallback const& right) = delete;
};

template <typename Result, typename ParamType1, typename ParamType2, bool chain = false>
class QueryCallback_2
{
    public:
        QueryCallback_2() : _stage(chain ? 0 : CALLBACK_STAGE_INVALID) { }

        //! The parameter of this function should be a resultset returned from either .AsyncQuery or .AsyncPQuery
        void SetFutureResult(std::future<Result> value)
        {
            _result = std::move(value);
        }

        std::future<Result>& GetFutureResult()
        {
            return _result;
        }

        bool IsReady()
        {
            return _result.valid() && _result.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
        }

        void GetResult(Result& res)
        {
            res = _result.get();
        }

        void FreeResult()
        {
            // Nothing to do here, the constructor of std::future will take care of the cleanup
        }

        void SetFirstParam(ParamType1 value)
        {
            _param_1 = value;
        }

        void SetSecondParam(ParamType2 value)
        {
            _param_2 = value;
        }

        ParamType1 GetFirstParam()
        {
            return _param_1;
        }

        ParamType2 GetSecondParam()
        {
            return _param_2;
        }

        //! Resets the stage of the callback chain
        void ResetStage()
        {
            if (!chain)
                return;

            _stage = 0;
        }

        //! Advances the callback chain to the next stage, so upper level code can act on its results accordingly
        void NextStage()
        {
            if (!chain)
                return;

            ++_stage;
        }

        //! Returns the callback stage (or CALLBACK_STAGE_INVALID if invalid)
        uint8 GetStage()
        {
            return _stage;
        }

        //! Resets all underlying variables (param, result and stage)
        void Reset()
        {
            SetFirstParam(NULL);
            SetSecondParam(NULL);
            FreeResult();
            ResetStage();
        }

    private:
        std::future<Result> _result;
        ParamType1 _param_1;
        ParamType2 _param_2;
        uint8 _stage;

        QueryCallback_2(QueryCallback_2 const& right) = delete;
        QueryCallback_2& operator=(QueryCallback_2 const& right) = delete;
};

#endif // _QUERY_CALLBACK_H