join.h

// -*- mode: c++; tab-width: 4; indent-tabs-mode: t; eval: (progn (c-set-style "stroustrup") (c-set-offset 'innamespace 0)); -*-
// vi:set ts=4 sts=4 sw=4 noet :
// Copyright 2013, The TPIE development team
// 
// This file is part of TPIE.
// 
// TPIE is free software: you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License as published by the
// Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
// 
// TPIE 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 Lesser General Public
// License for more details.
// 
// You should have received a copy of the GNU Lesser General Public License
// along with TPIE.  If not, see <http://www.gnu.org/licenses/>

#ifndef TPIE_PIPELINING_JOIN_H
#define TPIE_PIPELINING_JOIN_H

#include <tpie/pipelining/node.h>
#include <tpie/pipelining/factory_helpers.h>
#include <tpie/pipelining/pipe_base.h>

namespace tpie {
namespace pipelining {

template <typename T>
class join {
public:
    class source_base : public node {
    public:
        source_base(node_token token)
            : node(token)
        {
        }

        source_base(source_base &&) = default;
        
        virtual void push(const T & v) = 0;

    protected:
        ~source_base() {}
    };

    template <typename dest_t>
    class source_impl : public source_base {
    public:
        source_impl(dest_t dest, node_token token, source_base ** the_source)
            : source_base(token)
            , the_source(the_source)
            , dest(std::move(dest))
        {
            this->set_name("Join source", PRIORITY_INSIGNIFICANT);
            this->add_push_destination(this->dest);
        }

        source_impl(source_impl &&) = default;

        virtual void prepare() override {
            if (*the_source != NULL && *the_source != this) {
                // If join.source() is used twice, the second construction of node()
                // should fail since the node_token is already used.
                // Thus, this exception should never be thrown.
                throw exception("Attempted to set join source a second time");
            }
            *the_source = this;
        };

        virtual void push(const T & v) override {
            dest.push(v);
        }

    private:
        source_base ** the_source;
        dest_t dest;
    };

    pipe_begin<factory<source_impl, node_token, source_base **> > source() {
        return factory<source_impl, node_token, source_base **>(source_token, &the_source);
    }

    class sink_impl : public node {
    public:
        typedef T item_type;

        sink_impl(node_token source_token, source_base ** the_source)
            : the_source(the_source)
        {
            set_name("Join sink", PRIORITY_INSIGNIFICANT);
            add_push_destination(source_token);
        }

        virtual void begin() override {
            the_source_cache = *the_source;
        }

        void push(const T & v) {
            the_source_cache->push(v);
        }

    private:
        source_base * the_source_cache;
        source_base ** the_source;
    };

    pipe_end<termfactory<sink_impl, node_token, source_base **> > sink() {
        return termfactory<sink_impl, node_token, source_base **>(source_token, &the_source);
    }

    join() : the_source(NULL) {}
private:
    source_base * the_source;
    node_token source_token;
};

} // namespace pipelining
} // namespace tpie

#endif // TPIE_PIPELINING_JOIN_H