creation_queue.hpp

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// ****************************************************************************
// entity/component/creation_queue.h
//
// Represents a way to queue component creation in order to 
// reduce creation complexity from O(m*nlog(n)) to O(m+n)
//
// Copyright Chris Glover 2014-2015
//
// Distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// ****************************************************************************
#pragma once
#ifndef _ENTITY_COMPONENT_CREATIONQUEUE_H_INCLUDED_
#define _ENTITY_COMPONENT_CREATIONQUEUE_H_INCLUDED_

#include "entity/config.hpp" // IWYU pragma: keep
#include "entity/entity.hpp"
#include <algorithm>
#include <vector>
#include <utility>

// ----------------------------------------------------------------------------
//
namespace entity { namespace component
{
    template<typename ComponentPool>
    class creation_queue
    {
    public:

        typedef typename ComponentPool::type type;

        creation_queue(ComponentPool& p)
            : pool_(p)
        {}

        ~creation_queue()
        {
            flush();
        }

    #if ENTITY_SUPPORT_VARIADICS
        template<typename... Args>
        void push(weak_entity e, Args&&... args)
        {
            created_.push_back(std::make_pair(e, type(std::forward<Args>(args)...)));
        }
    #else
        void push(weak_entity e, type&& original)
        {
            created_.push_back(std::make_pair(e, std::move(original)));
        }
    #endif

        void flush()
        {
            std::sort(created_.begin(), created_.end());
            pool_.create_range(created_.begin(), created_.end());
            clear();
        }

        void clear()
        {
            created_.clear();
        }

    private: 

        // No copying.
        creation_queue(creation_queue const&);
        creation_queue operator=(creation_queue);

        std::vector<std::pair<weak_entity, type>> created_;
        ComponentPool& pool_;
    };
} } // namespace entity { namespace component

#endif // _ENTITY_COMPONENT_CREATIONQUEUE_H_INCLUDED_