QuartzCommandQueue.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include <type_traits>
#include "Containers/ConsumeAllMpmcQueue.h"
#include "Templates/UniquePtr.h"
#include "QuartzCompileTimeVisitor.h"
 
 
// forwards
namespace Audio::Quartz::PrivateDefs
{
    template <typename... Ts>
    class  TQuartzCommandQueue : public TVisitorPatternBase<Ts...>
    {
    private:
        // type aliasing for private code...
        template <class ConsumerBaseType>
        using TCommand = typename TVisitorPatternBase<Ts...>::template TVisitWithLambda<ConsumerBaseType>;
        using ICommandBase = typename TVisitorPatternBase<Ts...>::IVisitorBase;
        
    public:
        // type aliasing for client code...
        // IConsumerBase supports polymorphic access / containers of consumers
        using IConsumerBase = typename TVisitorPatternBase<Ts...>::IListenerBase;
 
        // TConsumerBase is the template base class which concrete consumer types should inherit from
        template <typename... ConsumerInterfaces>
        using TConsumerBase = typename TVisitorPatternBase<Ts...>::template TElementBase<ConsumerInterfaces...>;
    
    public:
        // begin TQuartzCommandQueue interface
        TQuartzCommandQueue() = default;
        ~TQuartzCommandQueue() = default;
 
        template <class TargetInterface>
        void PushLambda(TFunction<void(TargetInterface&)> InLambda)
        {
            Queue.ProduceItem(MakeUnique<TCommand<TargetInterface>>(MoveTempIfPossible(InLambda)));
        }
 
        // note: this is not currently needed for this implementation, but is an example of
        // polymorphic consumer usage and having multiple listeners listen to a single
        // set of pending commands.
        void PumpCommandQueue(IConsumerBase& InListener)
        {
            Queue.ConsumeAllFifo([&InListener](TUniquePtr<ICommandBase> InCommand)
            {
                InListener.Accept(*InCommand);
            });
        }
 
    private:
        UE::TConsumeAllMpmcQueue<TUniquePtr<ICommandBase>> Queue;
    }; // class TQuartzCommandQueue
} // namespace Audio::Quartz::PrivateDefs