JASS_anytime_query.h

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/*
    JASS_ANYTIME_QUERY.H
    --------------------
    Copyright (c) 2017 Andrew Trotman
    Released under the 2-clause BSD license (See:https://en.wikipedia.org/wiki/BSD_licenses)
*/
#pragma once

#include <stdint.h>

#include <atomic>
#include <string>
#include <vector>

/*
    CLASS JASS_ANYTIME_QUERY
    ------------------------
*/
class JASS_anytime_query
    {
    public:
        std::atomic<uint8_t> taken;             
        std::string query;                          

    public:
        /*
            JASS_ANYTIME_QUERY::JASS_ANYTIME_QUERY()
            ----------------------------------------
        */
        JASS_anytime_query() = delete;

        /*
            JASS_ANYTIME_QUERY::JASS_ANYTIME_QUERY()
            ----------------------------------------
        */
        JASS_anytime_query(const std::string &query) :
            taken(false),
            query(query)
                {
                /* Nothing */
                }

        /*
            JASS_ANYTIME_QUERY::JASS_ANYTIME_QUERY()
            ----------------------------------------
        */
        JASS_anytime_query(JASS_anytime_query &&original) :
            taken(original.taken.load()),
            query(original.query)
                {
                /*
                    Invalidate the original object.
                */
                original.query = "";
                original.taken = true;
                }

        /*
            JASS_ANYTIME_QUERY::GET_NEXT_QUERY()
            ------------------------------------
        */
        static std::string get_next_query(std::vector<JASS_anytime_query>&list, size_t &starting_from)
            {
            auto total_queries = list.size();
            while (starting_from < total_queries)
                {
                while (!list[starting_from].taken)                  
                    {
                    uint8_t expected = false;
                    if (list[starting_from].taken.compare_exchange_strong(expected, true))
                        return list[starting_from].query;
                    }
                starting_from++;
                }

            return std::string();
            }
    };