TokenStream.h

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/*
 * This file is part of KnowRob, please consult
 * https://github.com/knowrob/knowrob for license details.
 */
 
#ifndef KNOWROB_TOKEN_STREAM_H_
#define KNOWROB_TOKEN_STREAM_H_
 
#include <memory>
#include <mutex>
#include <shared_mutex>
#include <atomic>
#include <list>
#include <knowrob/queries/Token.h>
#include <knowrob/queries/EndOfEvaluation.h>
 
namespace knowrob {
    class TokenStream {
    public:
        TokenStream();
 
        virtual ~TokenStream();
 
        TokenStream(const TokenStream &) = delete;
 
        virtual void close();
 
        bool isOpened() const;
 
        class Channel {
        public:
            explicit Channel(const std::shared_ptr<TokenStream> &stream);
 
            ~Channel();
 
            Channel(const Channel &) = delete;
 
            static std::shared_ptr<Channel> create(const std::shared_ptr<TokenStream> &stream);
 
            void push(const TokenPtr &tok);
 
            void close();
 
            bool isOpened() const;
 
            bool hasValidIterator() const { return hasValidIterator_; }
 
            void invalidateIterator() { hasValidIterator_ = false; }
 
            uint32_t id() const;
 
        protected:
            // the stream of this channel
            std::shared_ptr<TokenStream> stream_;
            // iterator of this channel withing the stream
            std::list<std::shared_ptr<Channel>>::iterator iterator_;
            // flag indicating whether channel is open (i.e., no EOS received so far)
            std::atomic<bool> isOpened_;
            std::atomic<bool> hasValidIterator_;
            std::shared_mutex mutex_;
 
            friend class TokenStream;
        };
 
    protected:
        std::list<std::shared_ptr<Channel>> channels_;
        std::atomic<bool> isOpened_;
        std::mutex channel_mutex_;
 
        virtual void push(Channel &channel, const TokenPtr &tok);
 
        virtual void push(const TokenPtr &tok) = 0;
    };
}
 
#endif //KNOWROB_TOKEN_STREAM_H_