/*
 * Graph6Reader.hpp
 *
 *  Created on: Sep 26, 2017
 *      Author: heber
 */


#ifndef GRAPH_GRAPH6READER_HPP_
#define GRAPH_GRAPH6READER_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <istream>
#include <iterator>
#include <string>
#include <vector>

/** This functor parses graph6 formatted strings and returns number of nodes
 * and a edge list.
 *
 * This is inspired by https://github.com/adrianN/graph6/, only I found the code
 * there quite ugly and unnecessarily complicated: inheriting from std::iterator,
 * overriding all the operators (++, *, ...) for no apparent reason instead of
 * adding normal functions, ...
 *
 */
struct Graph6Reader
{
  typedef std::pair<int, int> edge_t;
  typedef std::vector< edge_t > edges_t;

  Graph6Reader() :
    column(1),
    row(-1),
    eos(false),
    bit_pos(-1),
    num_nodes(0)
  {}

  void operator()(std::istream &_graph_string);

  int get_num_nodes() const
  { return num_nodes; }

  const edges_t& get_edges() const
  { return edges; }

private:

  void scan_num_nodes(std::istream_iterator<unsigned char> &_it);
  void scan_edges(std::istream_iterator<unsigned char> &_it);
  void next_edge(std::istream_iterator<unsigned char> &_it);

private:
  int column;
  int row;
  bool eos;
  int bit_pos;
  static const int packet_size;

  //!> contains number of edges
  int num_nodes;
  //!> contains edge list
  std::vector< edge_t > edges;
};


#endif /* GRAPH_GRAPH6READER_HPP_ */