Class GraphEdgesIterable

tensorflow/core/graph/graph.h:501–557

Allows for iteration of the edges of a Graph, by iterating the underlying Graph.edges_ vector while skipping over null entries.

// Allows for iteration of the edges of a Graph, by iterating the underlying
// Graph.edges_ vector while skipping over null entries.
class GraphEdgesIterable {
 private:
  const std::vector<Edge*>& edges_;

 public:
  explicit GraphEdgesIterable(const std::vector<Edge*>& edges)
      : edges_(edges) {}

  typedef Edge* value_type;

  class const_iterator {
   private:
    // The underlying iterator.
    std::vector<value_type>::const_iterator iter_;

    // The end of the underlying iterator.
    std::vector<value_type>::const_iterator end_;

    // Advances iter_ until it reaches a non-null item, or reaches the end.
    void apply_filter() {
      while (iter_ != end_ && *iter_ == nullptr) {
        ++iter_;
      }
    }

   public:
    const_iterator(std::vector<value_type>::const_iterator iter,
                   std::vector<value_type>::const_iterator end)
        : iter_(iter), end_(end) {
      apply_filter();
    }

    bool operator==(const const_iterator& other) const {
      return iter_ == other.iter_;
    }

    bool operator!=(const const_iterator& other) const {
      return iter_ != other.iter_;
    }

    // This is the prefix increment operator (++x), which is the operator
    // used by C++ range iteration (for (x : y) ...).  We intentionally do not
    // provide a postfix increment operator.
    const_iterator& operator++() {
      ++iter_;
      apply_filter();
      return *this;
    }

    value_type operator*() { return *iter_; }
  };

  const_iterator begin() {
    return const_iterator(edges_.begin(), edges_.end());
  }
  const_iterator end() { return const_iterator(edges_.end(), edges_.end()); }
};