Program Listing for File chain.h

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#ifndef MESSAGE_FILTERS__CHAIN_H
#define MESSAGE_FILTERS__CHAIN_H

#include <vector>

#include "message_filters/simple_filter.h"
#include "message_filters/pass_through.h"

namespace message_filters
{
class ChainBase
{
public:
  virtual ~ChainBase() {}

  template<typename F>
  std::shared_ptr<F> getFilter(size_t index) const
  {
    std::shared_ptr<void> filter = getFilterForIndex(index);
    if (filter)
    {
      return std::static_pointer_cast<F>(filter);
    }

    return std::shared_ptr<F>();
  }

protected:
  virtual std::shared_ptr<void> getFilterForIndex(size_t index) const = 0;
};
typedef std::shared_ptr<ChainBase> ChainBasePtr;

template<typename M>
class Chain : public ChainBase, public SimpleFilter<M>
{
public:
  typedef std::shared_ptr<M const> MConstPtr;
  typedef MessageEvent<M const> EventType;

  Chain()
  {
  }

  template<typename F>
  Chain(F& f)
  {
    connectInput(f);
  }

  struct NullDeleter
  {
    void operator()(void const*) const
    {
    }
  };

  template<class F>
  size_t addFilter(F* filter)
  {
    std::shared_ptr<F> ptr(filter, NullDeleter());
    return addFilter(ptr);
  }

  template<class F>
  size_t addFilter(const std::shared_ptr<F>& filter)
  {
    FilterInfo info;
    info.add_func = std::bind((void(F::*)(const EventType&))&F::add, filter.get(), std::placeholders::_1);
    info.filter = filter;
    info.passthrough = std::make_shared<PassThrough<M> >();

    last_filter_connection_.disconnect();
    info.passthrough->connectInput(*filter);
    last_filter_connection_ = info.passthrough->registerCallback(typename SimpleFilter<M>::EventCallback(std::bind(&Chain::lastFilterCB, this, std::placeholders::_1)));
    if (!filters_.empty())
    {
      filter->connectInput(*filters_.back().passthrough);
    }

    size_t count = filters_.size();
    filters_.push_back(info);
    return count;
  }

  template<typename F>
  std::shared_ptr<F> getFilter(size_t index) const
  {
    if (index >= filters_.size())
    {
      return std::shared_ptr<F>();
    }

    return std::static_pointer_cast<F>(filters_[index].filter);
  }

  template<class F>
  void connectInput(F& f)
  {
    incoming_connection_.disconnect();
    incoming_connection_ = f.registerCallback(typename SimpleFilter<M>::EventCallback(std::bind(&Chain::incomingCB, this, std::placeholders::_1)));
  }

  void add(const MConstPtr& msg)
  {
    add(EventType(msg));
  }

  void add(const EventType& evt)
  {
    if (!filters_.empty())
    {
      filters_[0].add_func(evt);
    }
  }

protected:
  virtual std::shared_ptr<void> getFilterForIndex(size_t index) const
  {
    if (index >= filters_.size())
    {
      return std::shared_ptr<void>();
    }

    return filters_[index].filter;
  }

private:
  void incomingCB(const EventType& evt)
  {
    add(evt);
  }

  void lastFilterCB(const EventType& evt)
  {
    this->signalMessage(evt);
  }

  struct FilterInfo
  {
    std::function<void(const EventType&)> add_func;
    std::shared_ptr<void> filter;
    std::shared_ptr<PassThrough<M> > passthrough;
  };
  typedef std::vector<FilterInfo> V_FilterInfo;

  V_FilterInfo filters_;

  Connection incoming_connection_;
  Connection last_filter_connection_;
};
}  // namespace message_filters

#endif  // MESSAGE_FILTERS__CHAIN_H_