filter_nodes.h

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#ifndef GRPPI_FF_DETAIL_FILTER_NODES_H
#define GRPPI_FF_DETAIL_FILTER_NODES_H

#include "fastflow_allocator.h"

#include <ff/node.hpp>

namespace grppi {

namespace detail_ff {

template <typename T>
constexpr T * filtered_value() { 
  static_assert(sizeof(std::size_t) == sizeof(std::uintptr_t));
  return reinterpret_cast<T*>(std::size_t(ff::FF_EOS - 0x11));
}

template <typename Item, typename Predicate>
class filter_worker : public ff::ff_node_t<Item> {
public:
  filter_worker(Predicate && predicate) :
      predicate_{std::forward<Predicate>(predicate)}
  {}

  Item * svc(Item * p_item) {
    if (predicate_(*p_item)) {
      return p_item;
    }
    else {
      operator delete(p_item,ff_arena);
      return filtered_value<Item>();
    }
  }

private:
  Predicate predicate_;
};

template <typename Item>
class filter_collector : public ff::ff_node_t<Item> {
public:
  filter_collector() = default;

  Item * svc(Item * p_item) {
    if (p_item == filtered_value<Item>()) {
      return this->GO_ON;
    }
    else {
      return p_item;
    }
  }
};

template <typename Item>
class filter_emitter : public ff::ff_node_t<Item> {
public:
  filter_emitter() = default;

  Item * svc(Item * p_item) { return p_item; }
};



} // namespace detail_ff

} // namespace grppi

#endif